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Mutations of bone morphogenetic protein receptor type II are not found in patients with pulmonary hypertension and underlying connective tissue diseases.

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ARTHRITIS & RHEUMATISM
Vol. 46, No. 10, October 2002, pp 2817–2830
© 2002, American College of Rheumatology
LETTERS
damage, it is not surprising that some patients can fail to have
ACR20 improvement yet experience protection against radiographic damage. The Disease Activity Score (DAS) is an index
that combines tender and swollen joint counts, with a minor
contribution from 1 or 2 other measures (5). Because the
swollen joint count predominantly determines the DAS, and
because the swollen joint count is modestly correlated with
radiographic damage, the DAS is sometimes better correlated
with damage than is the ACR20. The analytic method used by
Boers to test this is an area under the curve approach, which
improves DAS precision. Because there is no similar approach
for the ACR20, it is more likely that DAS will correlate better
than the ACR20 with radiographic damage. Unfortunately,
Boers did not present correlations between DAS and radiographic progression for the Combinatietherapie Bij Reumatoide Artritis (COBRA) trial.
A prognostic measure for joint damage could be
useful. Indeed, because the swollen joint count (even though
its correlation with radiographs is poor) is the best method
known, it might be preferable to use that instead of the DAS.
The swollen joint count would be simpler to use compared with
the DAS, which is a complex combination of variables and has
several versions.
Although improvement that does not meet ACR20 is
possible in a clinical trial, there is a question of how clinically
meaningful such improvement might be. One of the questions
addressed by ATTRACT was whether the combination of
infliximab and methotrexate inhibited radiographic progression of damage in patients who failed to have a meaningful
clinical response. For this purpose, the ACR20 is the most
appropriate means for classifying responders. The issue of
whether patients who failed to achieve ACR20 were nonresponders or suboptimal responders is more semantic than
clinically relevant. An intriguing question is whether a treatment would be chosen if it had no measurable effect on
symptoms and signs of disease but slowed radiographic progression.
Several subanalyses using the ATTRACT data were
performed to validate the conclusion that inhibition of radiographic progression occurred in infliximab- and methotrexatetreated patients regardless of whether they had a meaningful
clinical response. In this regard, infliximab- and methotrexatetreated patients were divided into groups according to those
who did and those who did not experience a 20% improvement
in the number of swollen joints, the number of tender joints, or
the C-reactive protein level. In each of these groups, similar
and significant inhibition of radiographic progression, compared with that in patients treated with methotrexate alone,
was noted. Finally, patients treated with the combination of
infliximab and methotrexate were divided into groups according to those who failed to improve by ACR20 criteria at the
end of 54 weeks and those who failed to meet ACR20 criteria
at 13 or more of the 14 evaluations during the 54 weeks of the
ATTRACT trial. Both groups of “nonresponders” had significant and similar inhibition of radiographic progression compared with patients receiving methotrexate alone.
All of these results are consistent with the conclusion
that there is an important dichotomy between meaningful
DOI 10.1002/art.10446
Blocking tumor necrosis factor inhibits radiographic
damage even in patients who show minimal or no
clinical improvement: comment on the concise
communication by Boers
To the Editor:
We would like to comment on several aspects of the
recent concise communication by Boers (1) regarding results of
the Anti–Tumor Necrosis Factor Trial in Rheumatoid Arthritis with Concomitant Therapy (ATTRACT). In this trial,
inhibition of radiographic progression was noted in patients
treated with the combination of infliximab and methotrexate
regardless of whether they met American College of Rheumatology (ACR) 20% criteria for improvement in signs and
symptoms (2). Boers describes this result as being “counter to
intuition” and believes that the interpretation resulted from
inappropriate application of the ACR criteria. To support his
view, he provides data from a different, unrelated trial. We
would like to correct the possible misperceptions created by
these claims.
The first point relates to the use of the ACR criteria to
classify patients as responders. Indeed, the ACR preliminary
definition of improvement (the so-called ACR20) was created
and validated to identify patients with rheumatoid arthritis
(RA) enrolled in clinical trials who experienced a response in
symptoms and signs that approximated a clinician’s impression
of patient improvement (3). The ACR criteria comprised a
core set of measures evaluating different aspects of disease
activity, including joint counts, disability, acute-phase response, and measures of patient pain and global assessments.
Elements of the ACR20 were selected, in part, because results
of previous studies indicated that they predicted long-term
outcomes in RA, including radiographic joint damage (4). In
fact, the strongest such predictor, the swollen joint count, was
included in the core set (and highlighted in the ACR improvement criteria) for just this reason. Other measures in the core
set, such as the tender joint count and patient’s assessment of
pain (4), did not correlate with radiographic change, but were
included in the core set and definition of improvement,
because they were thought to be important indicators of
disease activity and in previous trials (3) showed evidence of
responsiveness to change.
The ACR20 (and ACR50) are now extensively used in
RA trials and have rationalized such trials, allowing us to
evaluate treatment efficacy in a manner that is more standardized and efficient than that used before these definitions
existed. Surely Boers, who was prominently involved in developing the core set and the ACR definition of improvement,
would not advocate returning to these earlier times, when
individual trials used their own outcome measures (and often
used many). Such an approach frequently led to problems in
data interpretation resulting from multiple comparisons.
One comment by Boers focuses on radiographic
change. Clearly, preventing radiographic damage is an important goal of RA therapy. Because many elements of the ACR
core set do not correlate well (or at all) with radiographic
2817
2818
LETTERS
Table 1. Relationship between clinical improvement and inhibition
of radiographic progression in ATTRACT patients treated with infliximab and methotrexate*
radiographic damage and clinical activity can be largely independent variables in patients with RA treated with the combination of infliximab and methotrexate.
Pearson’s correlation coefficients
Length of
treatment,
weeks
Measure
of disease
activity
Change in
radiographic
score
P
ACR-N
P
54
DAS 28
ACR-N
DAS 28
ACR-N
0.25
⫺0.14
0.18
⫺0.21
⬍0.001
0.011
0.003
⬍0.001
⫺0.71
⬍0.001
⫺0.76
⬍0.001
102
* ATTRACT ⫽ Anti–Tumor Necrosis Factor Trial in Rheumatoid
Arthritis with Concomitant Therapy; ACR-N ⫽ numeric American
College of Rheumatology measure of improvement; DAS ⫽ Disease
Activity Score.
clinical response to the combination of infliximab and methotrexate and inhibition of progressive radiographic damage. The
results suggest that one important impact of the combination
of infliximab and methotrexate is protection against progressive cartilage and bone damage even in patients who fail to
respond clinically to this combination. These findings imply
that tumor necrosis factor (TNF) has a critical role in progressive joint damage, even in patients in whom it plays only a
modest role in causing signs and symptoms of RA. Consistent
with this finding is the observation that patients who did not
achieve ACR20 response with the combination of infliximab
and methotrexate exhibited significantly less radiographic progression than did patients treated with methotrexate alone,
regardless of whether or not they improved.
Boers suggests that use of continuous measures of
disease activity might be a more appropriate way to establish a
relationship between radiographic progression and response to
therapeutic agents. To determine whether this would affect the
interpretation of the ATTRACT data, we analyzed clinical
activity using the DAS and the recently described numeric
ACR (ACR-N) (5,6). As shown in Table 1, there was a modest
but significant correlation between disease activity assessed
in either of these ways and inhibition of radiographic progression (r ⫽ ⫺0.14 to ⫺0.21 for ACR-N and r ⫽ 0.25 to 0.18 for
DAS). Importantly, however, the correlation was very modest
in that only 2–6% of the inhibition of radiographic progression
(r2) could be explained by changes in either continuous
measure of disease activity. Therefore, we believe it is safe to
conclude that there is only a very modest relationship between
clinical benefit caused by treatment with infliximab and methotrexate and inhibition of damage to articular structures.
Notably, the correlation between disease activity assessed by
the DAS and the ACR-N was also not complete (r ⫽ ⫺0.71 to
⫺0.76), perhaps because the former is weighted toward swollen joints, whereas the latter provides a broader view of disease
activity (3).
In summary, the data from ATTRACT demonstrate
that blocking TNF inhibits radiographic damage even in
patients who show minimal or no clinical benefit. This dichotomy in response was apparent when clinical activity was
analyzed using continuous variables or the ACR20. Finally,
and perhaps of greatest interest, the data clearly show that
Peter E. Lipsky, MD
National Institute of Arthritis and Musculoskeletal
and Skin Diseases
National Institutes of Health
Bethesda, MD
David T. Felson, MD, MPH
Boston University School of Medicine
Boston, MA
Ravinder N. Maini, MD, FRCP
Kennedy Institute of Rheumatology Division
Imperial College of Science, Technology and Medicine
London, UK
1. Boers M. Demonstration of response in rheumatoid arthritis patients who are nonresponders according to the American College of
Rheumatology 20% criteria: the paradox of beneficial treatment
effects in nonresponders in the ATTRACT trial. Arthritis Rheum
2001;44:2703–4.
2. Lipsky PE, van der Heijde DM, St Clair EW, Furst DE, Breedveld
FC, Kalden JR, et al, for the Anti-Tumor Necrosis Factor Trial in
Rheumatoid Arthritis with Concomitant Therapy Study Group.
Infliximab and methotrexate in the treatment of rheumatoid arthritis. N Engl J Med 2000;343:1594–1602.
3. Felson DT, Anderson JJ, Boers M, Bombardier C, Furst D,
Goldsmith C, et al. American College of Rheumatology preliminary
definition of improvement in rheumatoid arthritis. Arthritis Rheum
1995;6:727–35.
4. Felson DT, Anderson JJ, Boers M, Bombardier C, Chernoff M,
Fried B, et al. The American College of Rheumatology preliminary
core set of disease activity measures for rheumatoid arthritis clinical
trials. Arthritis Rheum 1993;36:729–40.
5. Van der Heijde DMFM, van’t Hof MA, van Riel PLCM, Theunisse
LM, Lubberts EW, van Leeuwen MA, et al. Judging disease activity
in clinical practice in rheumatoid arthritis: first step in the development of a disease activity score. Ann Rheum Dis 1990;49:916–20.
6. Van Riel PLCM, van Gestel AM. Area under the curve for the
American College of Rheumatology improvement criteria: a valid
addition to existing criteria in rheumatoid arthritis? [letter] Arthritis Rheum 2001;44:1719.
DOI 10.1002/art.10447
Reply
To the Editor:
I appreciate the opportunity to reply to the comments
by Lipsky and colleagues, and I am concerned that they may
have misinterpreted the point I was trying to make. Space
limitations may have obstructed clarity, for which I offer my
apologies.
To expand on my main point, I argue that use of any
measure of disease activity that bisects outcome (e.g.,
response–nonresponse) is likely to result in loss of information
when compared with use of continuous measures. The usefulness of such binary measures as prognostic indicators is,
therefore, suboptimal. In other words, when studying the
relationship (or lack thereof) between disease activity and
LETTERS
2819
Table 1. Analysis of indices and change in single disease activity measures in the COBRA trial, by responder status*
ACR nonresponders
Disease activity score AUC†
Pooled index, change after 6
months
Disease activity score, change
after 6 months
Erythrocyte sedimentation rate
Physician global assessment, 0–10
Patient global assessment, 0–10
Painful joint count
Health assessment questionnaire
Pain on visual analog scale, 1–10
Swollen joint count
MACTAR
Grip strength
ACR responders
Sulfasalazine
(n ⫽ 37)
COBRA
(n ⫽ 21)
P
Sulfasalazine
(n ⫽ 38)
116
0.34
101
1.06
0.05
⬍0.0001
91
1.29
⫺0.37
⫺1.05
0.001
⫺17
⫺0.3
⫺0.8
0
⫺0.26
⫺1.3
⫺1
3.7
4
⫺38
⫺2.3
⫺1.4
⫺4
⫺0.88
⫺2.4
⫺3
7.7
21
0.02
0.001
0.39
0.18
0.004
0.17
0.22
0.01
⬍0.0001
COBRA
(n ⫽ 56)
P
Overall P
85
1.59
0.26
0.02
0.003
⬍0.0001
⫺2.18
⫺2.54
0.08
⬍0.0001
⫺36
⫺3.1
⫺3.1
⫺16
⫺0.73
⫺2.8
⫺10
9.8
16
⫺41
⫺3.6
⫺2.8
⫺21
⫺1.19
⫺3.8
⫺12
10.6
26
0.38
0.002
0.52
0.06
0.04
0.05
0.15
0.4
0.008
0.002
0.001
0.25
0.0004
0.0001
0.002
0.001
0.0007
⬍0.0001
* COBRA ⫽ Combinatietherapie Bij Reumatoide Artritis; ACR ⫽ American College of Rheumatology; AUC ⫽ area under the curve; MACTAR ⫽
McMaster Toronto Arthritis patient preference questionnaire.
† AUC of absolute (not change) scores, by parametric analysis; P value slightly different from original nonparametric analysis.
radiographic progression of damage, ACR responder status is
a less-than-ideal indicator of disease activity.
In support of this view, I demonstrated that COBRA
therapy (a combination of step-down prednisolone, methotrexate, and sulfasalazine), like infliximab, slowed radiographic
progression of damage even in ACR20 nonresponders. However, in contrast to Lipsky et al, I did not interpret this as an
indication that COBRA appears to have a “critical role” in the
progression of bone and cartilage damage, even in patients in
whom clinical manifestations of RA are not apparently influenced by therapy (1). Also, I chose not to conclude that
“COBRA inhibits radiographic damage even in patients who
show minimal or no clinical benefit,” let alone that “damage
and clinical activity can be largely independent variables.”
Instead, I suspected that this finding was an artifact
caused by bisection of disease activity through use of the ACR
response criteria. This is by no means a fault of these criteria
and would most likely occur with other bisections (as Lipsky et
al, indeed, showed for the 20% response in the swollen joint
count and the C-reactive protein concentration [1]). The
artifact is revealed by my subsequent analysis. Using the
COBRA data set, I demonstrated that in the subgroup of
ACR20 nonresponders, disease activity (expressed as a continuous measure, i.e., the area under the curve of the DAS) was
lower in the COBRA group than in the sulfasalazine group.
Lipsky and colleagues have chosen not to replicate my
analysis using ATTRACT data, although an abstract presented
at the 2001 ACR meeting (2) suggests that the same phenomenon was demonstrated in that data set also. Instead, they take
issue with my choice of the DAS as a measure of disease
activity and then interpret my analyses in light of the relationship between DAS and swollen joints, as well as between DAS
and radiographic damage. However, and with all due respect,
this issue may not be relevant. I probably could have used any
other measure of disease activity, expressed as either area
under the curve or as 6-month change score, and shown the
same effect: that, in the subgroup of ACR20 nonresponders,
disease activity was lower among those using COBRA therapy
than among those treated with sulfasalazine. To prove this, I
repeated my previous analysis for the change after 6 months in
the pooled index (the primary trial outcome measure, a
weighted change score for erythrocyte sedimentation rate,
swollen and tender joint counts, physician’s global assessment,
and McMaster Toronto Arthritis functional index) and for
change scores in all core set measures, grip strength, and DAS
(Table 1). Among ACR nonresponders, for every measure, the
response (change in disease activity) was numerically greater
in the COBRA group. The difference between the COBRA
group and the sulfasalazine group was often statistically significant and clinically relevant.
I am also concerned about other aspects of the letter
from Lipsky et al. The implication that I would discount the
clinical usefulness of the ACR response criteria is without
ground, and such a conclusion cannot be reached based on my
concise communication. As I tried to make clear, I do oppose
use of the ACR criteria for purposes for which they were not
intended. The presentation by Lipsky et al of correlations
between DAS, ACR-N, and radiographic progression of damage is not very useful if the skewness of radiographic data is not
taken into consideration. Furthermore, these correlations are,
in my opinion, not relevant to the argument.
References regarding the ACR-N are problematic for
several reasons. The article by van der Heijde et al (3)
describing the DAS was originally published in 1990, which was
well before publication of any ACR response criteria, and the
letter from van Riel and van Gestel (4) was a rather blistering
critique of the ACR-N. In my recollection, the ACR-N was
never described, let alone formally validated, but suddenly
appeared “out of the blue” in the report of the trial of
etanercept versus high-dose methotrexate in early RA (5).
Finally, I’m no great fan of the DAS. Lipsky et al, however, use
reasoning I cannot follow to conclude that this measure is less
useful than the core set (or the ACR response) despite its
better correlation with damage.
2820
LETTERS
In summary, although a damage mechanism independent of disease activity is entirely possible (in fact, our group
will be presenting new data to support this theory), I maintain
that the current analyses of the COBRA data and probably the
ATTRACT data are incapable of showing such a mechanism.
As an aside, if Lipsky et al adhere to their reasoning, they
should at least admit that COBRA therapy is roughly equivalent to infliximab even in this respect.
For now, I believe that current observations are best
explained by the hypothesis that the threshold of disease
activity above which damage progression occurs is highly
individualized, with some RA patients needing only a little
“clinically irrelevant” disease activity for progression, and
others not progressing despite significant and persisting disease activity (6). Such heterogeneity hinders the study of this
relationship unless groups are large or followup is long.
Without doubt, such studies are further impeded by the
application of measures designed for other purposes. I continue to assert that the ACR criteria are best used to describe
and interpret trial results on disease activity at the individual
patient level, not as prognostic indicators.
Maarten Boers, MSc, MD, PhD
VU University Medical Center
Amsterdam, The Netherlands
1. Lipsky PE, van der Heijde DM, St Clair EW, Furst DE, Breedveld
FC, Kalden JR, et al, for the Anti-Tumor Necrosis Factor Trial in
Rheumatoid Arthritis with Concomitant Therapy Study Group.
Infliximab and methotrexate in the treatment of rheumatoid arthritis. N Engl J Med 2000;343:1594–1602.
2. Furst D, Yocum D, Han C, Keenan G, Bala M, Weisman W, et al.
Clinical benefits of infliximab ⫹ methotrexate treatment for patients with rheumatoid arthritis who were nonresponders by ACR
criteria [abstract]. Arthritis Rheum 2001;44:S80.
3. Van der Heijde DMFM, van’t Hof MA, van Riel PLCM, Theunisse
LM, Lubberts EW, van Leeuwen MA, et al. Judging disease activity
in clinical practice in rheumatoid arthritis: first step in the development of a disease activity score. Ann Rheum Dis 1990;49:916–20.
4. Van Riel PLCM, van Gestel AM. Area under the curve for the
American College of Rheumatology improvement criteria: a valid
addition to existing criteria in rheumatoid arthritis? [letter] Arthritis Rheum 2001;44:1719.
5. Bathon JM, Martin RW, Fleischmann RM, Tesser JR, Schiff MH,
Keystone EC, et al. A comparison of etanercept and methotrexate
in patients with early rheumatoid arthritis. N Engl J Med 2000;343:
1586–93.
6. Van Leeuwen MA, van Rijswijk MH, Sluiter WJ, van Riel PL,
Kuper IH, van de Putte LB, et al. Individual relationship between
progression of radiological damage and the acute phase response in
early rheumatoid arthritis: towards development of a decision
support system. J Rheumatol 1997;24:20–7.
DOI 10.1002/art.10689
Comment on the reply by Boers
To the Editor:
We are pleased that the series of letters initiated by Dr.
Boers’s concise communication has begun to shed light on the
issue of the relationship between clinical improvement and
radiographic outcome in the ATTRACT and COBRA data
sets. We agree with Dr. Boers that from a purely metrologic
point of view, dividing patients into responders and nonresponders can result in loss of information compared with the
use of continuous measures. For that reason, we provided
information in our response to Dr. Boers concerning the
significant but rather modest correlation between 2 continuous
measures of clinical activity, DAS and ACR-N, and radiographic outcome.
Use of the ACR responder criteria addresses the issue
that is in the minds of patients and practicing rheumatologists,
namely, whether there is a relationship between clinically
relevant disease improvement and radiographic outcome, and
in the mind of the clinical investigator, namely, whether
inflammation, as manifested by a clinically meaningful degree
of signs and symptoms, is associated with progressive radiographic damage. For clinicians, patients, and investigators, the
answer appears to be that protection from radiographic damage can be seen even in the absence of meaningful improvement in signs and symptoms of inflammation. Of course, there
may be evidence of minimal change in the degrees of inflammation that is less than that appreciated reproducibly by a
clinician as improvement that still could contribute to progressive radiographic damage. However, the hypothesis that “the
threshold of disease activity above which damage progression
occurs is highly individualized” is nearly impossible to test,
given the realities of clinical trials and the relative imprecision
of clinical and radiographic tools.
We performed the analysis that Dr. Boers suggested,
but our interpretation of the results is somewhat different from
his. Indeed, in ATTRACT, infliximab-plus-methotrexate nonresponders assessed by ACR20 achieved significant improvement in mean ACR-N relative to methotrexate-only nonresponders at weeks 30, 54, and 102 (P ⬍ 0.05). In addition,
infliximab-plus-methotrexate nonresponders, as assessed by
ACR20 at 102 weeks, manifested significant improvement in 5
of 7 ACR components (swollen joint count, tender joint count,
C-reactive protein, physician global assessment and patient
pain assessment) relative to methotrexate-only nonresponders
(P ⬍ 0.05). The infliximab-plus-methotrexate nonresponders
also demonstrated significant improvement in the physical
component summary score of the Short Form 36 relative to
methotrexate-only nonresponders (P ⫽ 0.006). The results
indicate that in ATTRACT, as in COBRA, nonresponders to
the more effective therapy fared better clinically compared
with nonresponders receiving the control therapy. Despite this,
the correlation between improvement in disease activity using
continuous variables (DAS, ACR-N) and radiographic progression was very modest, implying that changes in signs and
symptoms could account for only a small proportion of the
radiographic protection. As opposed to the contention of Dr.
Boers, we believe that the lack of a more important correlation
between improvement in continuous measures of disease
activity and radiographic benefit is very telling in the interpretation of the results, and strongly suggests that radiographic
damage and clinical activity can be largely independent variables.
In summary, we agree with Dr. Boers that “a damage
mechanism independent of disease activity is entirely possible.” We await with interest the new data from the Boers group
that will apparently support this conclusion. We disagree,
however, with Dr. Boers, in that we believe that the
LETTERS
2821
ATTRACT data strongly support this contention. In addition,
we cannot agree that COBRA and infliximab plus methotrexate are “roughly equivalent,” because no direct comparisons
have been performed. Finally, we agree with Dr. Boers that
ACR criteria are not useful as a prognostic indicator to predict
radiographic outcome in patients treated with infliximab and
methotrexate, because both responders and nonresponders
manifest protection from structural damage.
Peter E. Lipsky, MD
National Institute of Arthritis
and Musculoskeletal and Skin Diseases
National Institutes of Health
Bethesda, MD
Ravinder N. Maini, MD, FRCP
Kennedy Institute of Rheumatology Division
Imperial College of Science, Technology and Medicine
London, UK
DOI 10.1002/art.10469
Case series of selective anti–tumor necrosis factor ␣
therapy using infliximab in patients with
nonresponsive chronic HLA–B27–associated anterior
uveitis: comment on the articles by Brandt et al
To the Editor:
Recent reports by Brandt et al (1,2) described the
effectiveness of selective anti–tumor necrosis factor ␣ (TNF␣)
therapy in ankylosing spondylitis. Because ⬃25–30% of patients with spondylarthropathies are affected by a concurrent
eye disease such as anterior uveitis (3), we have been looking
at the effectiveness of infliximab for HLA–B27–associated
recurrent or chronic uveitis that is nonresponsive to conventional therapy with systemic or local corticosteroids and
methotrexate (MTX). We now report on 3 patients with
chronic uveitis who were treated with infliximab.
Patient 1 had a 2-year history of recurrent uveitis
flares. She experienced an average of 2–3 episodes per year
and was treated with local and, if necessary, systemic corticosteroids for each episode. One year ago she was treated with a
single dose of infliximab (10 mg/kg body weight) after an acute
flare, and her uveitis resolved within 1 week. She experienced
another flare 6 months later and from then on had repeated
episodes of uveitis despite high doses of local as well as
systemic corticosteroids, in addition to MTX (17.5 mg/week).
Her visual acuity worsened, from 20/20 to 20/30, because of the
development of cystoid macular edema. Infliximab was given
again, at 5 mg/kg body weight. Systemic and local corticosteroid therapy was stopped, but MTX was continued at 12.5
mg/week. One week after the first infliximab infusion, the
uveitis was under control. She received a second infusion 2
weeks later and a third after another 4 weeks. The uveitis
remained in remission for 5 months, her visual acuity returned
to 15/20, and the dosage of MTX was reduced to 7.5 mg/week.
Unfortunately, 5 months after her last infusion of infliximab,
she had another relapse.
Patient 2, with an 8-year history of recurrent episodes
of anterior uveitis, developed iridocyclitis while being treated
with MTX (12.5 mg/week) for ankylosing spondylitis. Despite
intensive administration of corticosteroid drops (every hour),
the uveitis could not be brought to full remission. Seven weeks
after onset of uveitis, 1⫹ anterior chamber cells were still
visible. Her visual acuity decreased, from 20/25 to 20/50, due to
cystoid macular edema, and infliximab therapy was started.
Five days after administering infliximab, 5 mg/kg body weight,
her visual acuity returned to 20/25, and only rare anterior
chamber cells were seen. Additional infusions of infliximab (5
Table 1. Disease activity in patients with chronic uveitis treated with infliximab*
Patient 1
Activity
Cells
Flare
Visual acuity
Therapy
Patient 2
Activity
Cells
Flare
Visual acuity
Therapy
Patient 3
Activity
Cells
Flare
Visual acuity
Therapy
Baseline
Week 2
Week 8
2⫹
1⫹
20/25
CS drops every 2 hours; oral pred 32.5 mg/day;
MTX 17.5 mg/week
0
0
15/20
MTX 12.5 mg/week
0
0
15/20
MTX 7.5 mg/week
1⫹
0
20/50
CS drops every hour; MTX 12.5 mg/week
0
0
20/25
MTX 12.5 mg/week
0
0
15/20
MTX 12.5 mg/week
0
0
20/100
Oral pred 5 mg/day; MTX
12.5 mg/week
0
0
20/30
Oral pred 5 mg or 2.5 mg/day (alternate
days); MTX 12.5 mg/week
2⫹
1⫹
20/100
CS drops every 2 hours; oral pred 20 mg/day;
MTX 20 mg/week
* Cells ⫽ anterior chamber cells; CS ⫽ corticosteroids; pred ⫽ prednisone; MTX ⫽ methotrexate.
2822
mg/kg body weight) were given at weeks 2 and 6. Two weeks
after initiation of infliximab therapy, not only had the uveitis
improved, but her active ankylosing spondylitis had subsided as
well. Three weeks after the first infusion of infliximab, her
visual acuity improved to 20/20, with only residual subtle
pigment epithelial changes present in the macula. Fluorescence angiography was negative for edema. At her last visit, 5
months after initiation of infliximab therapy, the uveitis as well
as the ankylosing spondylitis remained in remission, and her
visual acuity was 15/20.
Patient 3, with a known history of ankylosing spondylitis, had experienced recurrent flares of uveitis for the past 7
years. Within the last 3 years, the uveitis could not be
controlled with systemic steroids (17.5 mg/day) plus MTX (20
mg/week). Because of longstanding inflammation that worsened every time steroid therapy was tapered below 17.5
mg/day, she developed chronic cystoid macular edema, which
resulted in a decrease in her visual acuity to 20/100. Two weeks
after receiving only 1 infusion of infliximab (5 mg/kg body
weight), her uveitis subsided completely. The systemic steroid
therapy was reduced to 5 mg/day, and the dosage of MTX was
reduced to 12.5 mg/week. Because she developed flu-like
symptoms following infliximab therapy, she refused any further
treatment with infliximab. Nevertheless, uveitis has not recurred within the last 3 months. In the meantime, the chronic
macular edema resolved almost completely, and her visual
acuity improved, from 20/100 to 20/30.
In our case series (Table 1), all patients had developed
chronic uveitis before receiving infliximab therapy, despite
combined therapy with MTX and corticosteroids. Because
infliximab was shown to be very effective in the treatment of
various HLA–B27–associated conditions such as ankylosing
spondylitis (1,2) and the fact that uveitis went into remission in
all of our patients, it seems that this group of patients responds
especially well to infliximab therapy. One patient had a recurrence of uveitis at month 5 of followup, a time at which
infliximab may no longer be detectable in the body.
Reiff and colleagues recently described treatment with
etanercept (Immunex, Seattle, WA), a soluble p75 TNF receptor, in children with juvenile rheumatoid arthritis (JRA) who
had concurrent chronic corticosteroid- and MTX-resistant
uveitis (4). After 6 months of treatment, uveitis was in remission in 3 of 14 eyes. Five of 14 eyes showed improvement, 5
remained unchanged, and 1 deteriorated. The fact that uveitis
went into remission in only 20% of the cases—a much smaller
percentage than in our study—might be attributable to the
difference in the patients treated. It must be considered that
clinically, anterior uveitis is a diverse collection of diseases (5),
and that JRA and HLA–B27–associated intraocular inflammatory diseases are distinct entities. In addition, we used infliximab rather than etanercept in our study. This might be of
some relevance, because in a second study (6) of 16 patients
treated with either etanercept (n ⫽ 14) or infliximab (n ⫽ 2)
for inflammatory eye diseases or associated joint disease, only
4 of the 14 etanercept patients showed an improvement in the
ocular inflammation, as opposed to improvement in both
infliximab patients.
We would like to stress the fact that the number of
patients in our case series is small because one of our goals was
to keep the group of patients as homogenous as possible. Thus,
our group included only patients with HLA–B27–associated
LETTERS
chronic uveitis, most of whom usually respond adequately to
corticosteroids and, if necessary, systemic MTX (7). The good
clinical response to infliximab of other HLA–B27–associated
inflammatory diseases, such as ankylosing spondylitis and
psoriatic arthritis (1,2,8), supports our finding that this group
of patients seems to be especially responsive to selective
anti-TNF␣ therapy.
In conclusion, in our case series, infliximab was highly
effective in treating patients with HLA–B27–associated uveitis
resistant to current antiinflammatory and immunosuppressive
therapy. The series was small, however, and additional larger
studies will be needed to further evaluate the effectiveness of
infliximab therapy in this entity.
Yosuf El-Shabrawi, MD
Josef Hermann, MD
Karl-Franzens University
Graz, Austria
1. Brandt J, Haibel H, Cornely D, Golder W, Gonzalez J, Reddig J, et
al. Successful treatment of active ankylosing spondylitis with the
anti–tumor necrosis factor ␣ monoclonal antibody infliximab. Arthritis Rheum 2000;43:1346–52.
2. Brandt J, Haibel H, Sieper J, Reddig J, Braun J. Infliximab
treatment of severe ankylosing spondylitis: one-year followup.
Arthritis Rheum 2001;44:2936–7.
3. Kahn M. An overview of clinical spectrum and heterogeneity of
spondyloarthropathies. Rheum Dis Clin North Am 1992;18:1–10.
4. Reiff A, Takei S, Sadeghi S, Stout A, Shaham B, Bernstein B, et al.
Etanercept therapy in children with treatment-resistant uveitis.
Arthritis Rheum 2001;44:1411–5.
5. Wakefield D. Report on the 4th International Symposium of Ocular
Inflammation. Ocul Immunol Inflamm 1997;5:1–9.
6. Smith JR, Levinson RD, Holland GN, Jabs DA, Robinson MR,
Whitcup SM, et al. Differential efficacy of tumor necrosis factor
inhibition in the management of inflammatory eye disease and
associated rheumatic disease. Arthritis Rheum (Arthritis Care Res)
2001;45:252–7.
7. Samson C, Waheed N, Baltatzis S, Foster CS. Methotrexate therapy
for chronic noninfectious uveitis: analysis of a case series of 160
patients. Ophthalmology 2001;108:1134–9.
8. Ogilvie AL, Antoni C, Dechant C, Manger B, Kalden JR, Schuler
G, et al. Treatment of psoriatic arthritis with antitumor necrosis
factor-alpha antibody clears skin lesions of psoriasis resistant to
treatment with methotrexate. Br J Dermatol 2001;144:587–9.
DOI 10.1002/art.10470
Reply
To the Editor:
Eye involvement is quite common in inflammatory
rheumatic conditions. Among 407 patients with uveitis, Behcet’s disease, spondylarthritides (SpA), and sarcoidosis were
the most frequent diagnoses possibly associated with rheumatologic symptoms (1). In other rheumatic diseases such as
rheumatoid arthritis (RA), different anatomic parts of the eye,
such as the sclera, are affected. Although the pathophysiologic
and genetic backgrounds of these diseases are thought to be
rather different, common denominators such as the proinflammatory cytokine TNF␣ seem to be involved in some, but
LETTERS
clearly not all, immunologically mediated diseases. As an
outstanding example, anti-TNF therapy is not effective in
multiple sclerosis (2).
In inflammatory eye diseases, some positive but also
controversial results on the role of TNF␣ have been reported,
from experimental studies (3–5) and more recently from early
pilot studies (6–8), such as that described in the letter from our
Austrian colleagues, to which we now respond.
In an early study (3), mice with endotoxin-induced
uveitis (EIU) were pretreated with either repeated injections
of TNF␣ or with a single injection of antibody against it.
Although both pretreatments conferred protection against the
systemic toxic effects of lipopolysaccharides (LPS), TNFresistant mice and those treated with anti-TNF␣ antibody
demonstrated an exacerbation of EIU when compared with
control animals. The authors concluded, “Unlike its apparent
participation in the systemic effect of endotoxin, TNF␣ is not
directly involved in the pathogenesis of EIU and may even
protect against the inflammatory processes of this disease.”
In an investigation of TNF␣ in rabbits with uveitis
induced by intravitreal injection of LPS (4), peak concentrations of aqueous TNF␣ preceded peak aqueous leukocyte
counts. Administration of anti-TNF␣ monoclonal antibody (10
␮g) suppressed the number of infiltrating cells by 50% and
suppressed protein leakage by 40%.
TNF␣ seems also to have an important proinflammatory role in experimental autoimmune uveoretinitis (EAU),
which serves as a model for several immune-mediated diseases
that affect the eye in humans (5). Mice treated with 100 ␮l or
300 ␮l of rabbit antiserum or polyclonal antibodies to human
TNF␣ significantly improved when the treatment was given
during the afferent but not during the efferent stage of EAU.
In patients with Behçet’s disease, permanent loss of
vision resulting from relapsing ocular inflammation occurs
frequently. As recently reported (9), a single infusion of
infliximab to 5 patients with relapsing panuveitis, given at the
immediate onset of last relapse, led to remission of ocular
inflammation within the first 24 hours, and complete suppression was seen 7 days after treatment in all patients. Similarly,
other investigators reported beneficial effects in Behçetassociated uveitis (10). If confirmed in prospective studies, this
can be regarded as a significant success of medicine because of
the bad prognosis of uveitis in Behçet’s disease despite intensive immunosuppressive therapy.
In an earlier, retrospective study (6) of 16 patients
between the ages of 7 and 78 (8 with RA, 3 with JRA, 1 with
ankylosing spondylitis [AS], 1 with psoriatic SpA, and 3 with
uveitis with no concomitant rheumatic disease), 14 received
etanercept and 2 received infliximab for either inflammatory
eye disease (9 uveitis, 7 scleritis) or associated joint disease.
Although 12 (100%) of 12 patients with active articular
inflammation had improvement of joint disease, only 6 (38%)
of 16 with ocular inflammation experienced improvement of
eye disease. In 5 patients, first episodes of inflammatory eye
disease occurred while they were taking a TNF inhibitor. From
these data, it is not clear whether anti-TNF therapy is beneficial for inflammatory eye disease in patients with rheumatic
conditions. More recently, treatment with infliximab was reported to be beneficial in patients with uveitis associated with
Crohn’s disease (7).
In a prospective study (8) involving 10 children with
2823
chronic active uveitis, 7 had uveitis associated with pauciarticular JRA, and 5 were antinuclear antibody (ANA) positive. All
patients had failed previous therapy with topical steroids and
methotrexate and/or cyclosporine. All were treated with etanercept at a dosage of 0.4 mg/kg twice weekly for the first 3
months, and then, if eyes did not improve, with 25 mg twice
weekly (mean 1.1 mg/kg) for at least 3 additional months.
Within 3 months, 10 (63%) of 16 affected eyes showed a rapid
decrease in anterior chamber cell density (P ⫽ 0.017), including remission in 4 eyes. An exacerbation of uveitis during
etanercept therapy occurred in only 1 child (7%). Following a
dose increase, to an average of 1.1 mg/kg after 3 months in 7
children, no further improvement was noted. The natural
course of uveitis in patients who are HLA–B27 positive versus
those who are ANA positive is known to be rather different.
The authors concluded that treatment of uveitis with etanercept in systemic and/or topical form (which has not been
studied so far) needs further study.
In their letter, El-Shabrawi and Hermann reported a
beneficial effect of infliximab with HLA–B27–associated uveitis in 3 patients, and these authors recently published their
1-year experience with this treatment in abstract form (11).
Thus, the results from these uncontrolled observations are
basically positive. In addition, our own experience with infliximab in a randomized trial with AS patients (12) is also
suggestive of a beneficial effect, because 3 patients in the
placebo group, compared with 1 patient in the infliximab
group, developed uveitis over 3 months. Nevertheless, there
seems to be a need to contribute some points for discussion
from the perspective of rheumatologists.
In the vast majority of patients with SpA, the natural
course of anterior uveitis seems rather benign. Thus, we think
that anti-TNF therapy should be considered only in severe
refractory cases. In this regard, there is a need to mention that
some evidence suggests that sulfasalazine is effective in preventing episodes of uveitis in SpA (13). In contrast to methotrexate, sulfasalazine was also shown to be effective for peripheral arthritis in AS and other SpA (14).
El-Shabrawi and Hermann used the one-shot approach, administering a high dose (10 mg) of infliximab in
some patients. Because this was partly successful in uveitis and
apparently also in Crohn’s disease, it raises the questions of
whether this approach should be tried initially in SpA in
general, and whether the high dosage is associated with more
severe side effects. The only trial on dosage is a small, open
study (15). However, it seems clear that there is a need for a
new approach using individual dosing regimens (which are
difficult to study). Concerning side effects, there is no evidence
for a major dose effect to date, but this issue is increasingly
relevant because severe and even fatal side effects have been
reported with use of both anti-TNF agents (16).
Taken together, these findings provide increasing evidence that anti-TNF therapy is efficacious in SpA—possibly
even more than in RA. It is not completely clear whether all
types of organ involvement and all possible targets of SpA (i.e.,
spinal inflammation, peripheral arthritis, enthesitis, psoriasis,
colitis, uveitis) are equally affected, and whether both currently
available anti-TNF agents are equally effective. Currently,
there is some evidence that both infliximab and etanercept are
beneficial for spinal inflammation, peripheral arthritis, en-
2824
LETTERS
thesitis, and psoriasis, but there is no evidence for efficacy of
etanercept in Crohn’s disease (17).
As already discussed, there are no randomized studies
on the efficacy of anti-TNF therapy in uveitis. Based on the
open observations published, there is hope that both infliximab
and etanercept might be effective in some, but clearly not all,
cases, which could be very interesting for scientific purposes,
especially in relation to the pathogenesis of uveitis and individual courses of disease.
Jürgen Braun, MD
Rheumazentrum Ruhrgebiet
Herne, Germany
and University Hospital Benjamin Franklin
Joachim Sieper, MD
University Hospital Benjamin Franklin
and Rheumatology Research Center
Berlin, Germany
1. Bañares A, Jover JA, Fernández-Gutiérrez B, Benı́tez del Castillo
JM, Garcı́a J, Vargas E, et al. Patterns of uveitis as a guide in
making rheumatologic and immunologic diagnoses. Arthritis
Rheum 1997;40:358–70.
2. Van Oosten BW, Barkhof F, Truyen L, Boringa JB, Bertelsmann
FW, von Blomberg BM, et al. Increased MRI activity and immune
activation in two multiple sclerosis patients treated with the
monoclonal anti-tumor necrosis factor antibody cA2. Neurology
1996;47:1531–4.
3. Kasner L, Chan CC, Whitcup SM, Gery I. The paradoxical effect
of tumor necrosis factor alpha (TNF-alpha) in endotoxin-induced
uveitis. Invest Ophthalmol Vis Sci 1993;34:2911–7.
4. Sartani G, Silver PB, Rizzo LV, Chan CC, Wiggert B, Mastorakos
G, et al. Anti-tumor necrosis factor alpha therapy suppresses the
induction of experimental autoimmune uveoretinitis in mice by
inhibiting antigen priming. Invest Ophthalmol Vis Sci 1996;37:
2211–8.
5. Mo JS, Matsukawa A, Ohkawara S, Yoshinaga M. Involvement of
TNF alpha, IL-1 beta and IL-1 receptor antagonist in LPS-induced
rabbit uveitis. Exp Eye Res 1998;66:547–57.
6. Smith JR, Levinson RD, Holland GN, Jabs DA, Robinson MR,
Whitcup SM, et al. Differential efficacy of tumor necrosis factor
inhibition in the management of inflammatory eye disease and
associated rheumatic disease. Arthritis Rheum (Arthritis Care
Res) 2001;45:252–7.
7. Fries W, Giofre MR, Catanoso M, Lo GR. Treatment of acute
uveitis associated with Crohn’s disease and sacroileitis with infliximab. Am J Gastroenterol 2002;97:499–500.
8. Reiff A, Takei S, Sadeghi S, Stout A, Shaham B, Bernstein B, et al.
Etanercept therapy in children with treatment-resistant uveitis.
Arthritis Rheum 2001;44:1411–5.
9. Sfikakis PP, Theodossiadis PG, Katsiari CG, Kaklamanis P,
Markomichelakis NN. Effect of infliximab on sight-threatening
panuveitis in Behcet’s disease. Lancet 2001;358:295–6.
10. Munoz-Fernandez S, Hidalgo V, Fernandez-Melon J, Schlincker
A, Martin-Mola E. Effect of infliximab on threatening panuveitis
in Behcet’s disease. Lancet 2001;358:1644.
11. El-Shabrawi Y, Hermann J. Anti-TNFA therapy with infliximab in
the treatment of HLA B27 associated acute anterior uveitis: a one
year follow up [abstract]. Arthritis Rheum 2001;44 Suppl 9:S123.
12. Braun J, Brandt J, Listing J, Zink A, Alten R, Krause A, et al.
Treatment of active ankylosing spondylitis with infliximab: a
randomised controlled multicenter trial. Lancet 2002;359:1187–93.
13. Benitez-Del-Castillo JM, Garcia-Sanchez J, Iradier T, Banares A.
Sulfasalazine in the prevention of anterior uveitis associated with
ankylosing spondylitis. Eye 2000;14:340–3.
14. Clegg DO, Reda DJ, Abdellatif M. Comparison of sulfasalazine
and placebo for the treatment of axial and peripheral articular
manifestations of the seronegative spondylarthropathies: a Department of Veterans Affairs cooperative study. Arthritis Rheum
1999;42:2325–9.
15. Brandt J, Haibel H, Reddig J, Sieper J, Braun J. Successful
treatment of severe undifferentiated spondyloarthropathy with the
anti-tumor necrosis factor ␣ monoclonal antibody infliximab.
J Rheumatol 2002;29:118–22.
16. Keane J, Gershon S, Wise RP, Mirabile-Levens E, Kasznica J,
Schwieterman WD, et al. Tuberculosis associated with infliximab,
a tumor necrosis factor alpha-neutralizing agent. N Engl J Med
2001;345:1098–104.
17. Sandborn WJ, Hanauer SB, Katz S, Safdi M, Wolf DG, Baerg RD,
et al. Etanercept for active Crohn’s disease: a randomized, doubleblind, placebo-controlled trial. Gastroenterology 2001;121:
1088–94.
DOI 10.1002/art.10473
Is expression of intracellular citrullinated proteins in
synovial tissue specific for rheumatoid arthritis?
Comment on the article by Baeten et al
To the Editor:
The presence in serum of autoantibodies directed to
citrullinated antigens is highly specific for rheumatoid arthritis
(RA) (1). This might theoretically be explained by an immune
response to specific overexpression of citrullinated antigens in
rheumatoid synovium (2) or, alternatively, by an abnormal
humoral response to the presence of citrullinated proteins,
which could be present in any inflamed synovial tissue. A
recent report by Baeten and colleagues suggested that the
expression of citrullinated proteins in synovial tissue is specific
for RA (3). In that study, citrulline-positive cells were detected
in the synovial membrane of 50% of the RA patients but in
none of the controls.
In a separate experiment, Baeten et al examined biopsy
samples obtained from 33 patients from the Academic Medical
Center/University of Amsterdam: 19 with RA, 3 with osteoarthritis, 5 with psoriatic arthritis, 1 with reactive arthritis (ReA),
and 5 with other arthritides. The biopsy sections were coded
and randomly analyzed. Citrulline-positive cells were detected
in the synovial membrane of 33% of the patients with RA but
in none of the controls, confirming the results of MassonBessiere et al (2). These data could suggest a novel diagnostic
tool for discriminating RA from other inflammatory joint
diseases by examination of synovial biopsy samples.
The expression of intracellular citrullinated proteins in
synovial tissue was also investigated at the Academic Medical
Center/University of Amsterdam. We included 14 patients
with RA, 10 with osteoarthritis (OA), 7 with ReA, and 23 with
other arthritides. The rabbit anti–L-citrulline polyclonal antibody (6 ␮g/ml) and staining protocol were identical to those
used by Baeten and colleagues (3). Citrulline-containing antigens were observed in synovial cryostat sections of anti–
citrulline-containing peptide (anti-CCP)–positive and antiCCP–negative patients. Of importance, replacing the rabbit
anti–L-citrulline antibody with control rabbit anti–fluorescein
isothiocyanate (anti-FITC) antibody (Dako, Glostrup, Den-
LETTERS
mark) revealed positive staining in synovial tissue of several
RA patients, suggesting nonspecific binding in the negative
controls. The same staining was seen when lower concentrations of antibody were used (3 ␮g/ml and 1.5 ␮g/ml).
Excluding cells that stained with the negative control
anti-FITC antibody in consecutive sections, we found synovial
tissue expression of citrullinated proteins in 57% of the
patients with RA, 30% of the patients with OA, 29% of the
patients with ReA, and 26% of the patients with other
arthritides. Subsequently, a recombinant single-chain variable
fragment (scFv) monoclonal antibody was selected against a
cyclic citrullinated peptide from a patient antibody-fragment
phage-display library (Raats J: unpublished observations). This
scFv and patient antibodies affinity-purified with a citrullinated peptide were both used for immunohistochemical staining. Using a control scFv antibody, staining was absent in the
negative controls. Again, we detected citrullinated antigens in
2825
both RA and non-RA tissue (4). Staining with scFv monoclonal antibody was noted in synovial lining cells and in (peri)vascular areas in 43% of the RA patients, 54% of the OA patients,
56% of the ReA patients, and 43% of the patients with other
arthritides. Similar results were obtained when horseradish
peroxidase–labeled affinity-purified human IgG against citrullinated peptides was used. Expression of citrullinated antigens
in synovial tissue was not associated with the presence of
anti-CCP autoantibodies in serum or synovial fluid. Thus, we
could not confirm the specificity of intracellular citrullinated
protein expression in rheumatoid synovial tissue, and we
observed nonspecific binding by rabbit immunoglobulins to
RA synovium.
To understand the discrepancy between the results
obtained in the 2 laboratories, we evaluated in Amsterdam the
sections that were stained in Ghent. Similar to the findings in
our earlier experiments, 2 populations of citrulline-containing
Figure 1. Double immunohistochemical staining in rheumatoid synovial tissue. A, Field of CD38⫹ plasma cells (red) and
citrulline-positive cells (rabbit anti–L-citrulline polyclonal antibody) (blue). C, Field of CD38⫹ plasma cells (red) and control
antibody (blue) (rabbit anti–fluorescein isothiocyanate [anti-FITC]). An alkaline phosphatase technique was used to detect
citrulline-positive cells and control antibody; peroxidase was used to detect CD38⫹ plasma cells. Arrows indicate doublestained cells. B, Citrulline-positive cells (rabbit anti–L-citrulline polyclonal antibody). D, Control antibody (rabbit anti-FITC).
(Single-stain peroxidase technique, Mayer’s hemalum counterstained; original magnification ⫻ 400.)
2826
LETTERS
cells were identified: strongly positive cells (ⱕ3 cells/biopsy
section) and cells that exhibited weaker staining. The cells with
intense staining were found mainly in RA synovium, whereas
weaker staining was detected in both RA and control tissue.
Only sections with strongly positive cells were judged as
positive by the investigators in Ghent, whereas we included
both cell populations in our evaluation. Using the same
microscopic evaluation, we could confirm the results from
Ghent. However, cells appeared strongly positive, in most
cases the same cells were positive in control experiments using
the irrelevant anti-FITC rabbit antibody, suggesting nonspecific binding of rabbit immunoglobulins to cells that are
specifically increased in RA synovium.
Because the number of plasma cells is specifically
increased in rheumatoid synovial tissue (5), and, according to
previous experience, rabbit immunoglobulins may bind nonspecifically to these cells, we hypothesized that rabbit anti–Lcitrulline polyclonal antibody may bind to (presumably rheumatoid factor–producing) plasma cells. This hypothesis was
confirmed by double-staining experiments using the rabbit
anti–L-citrulline antibody with phenotypic markers to detect T
cells (CD3), B cells (CD22), plasma cells (CD38 and CD138),
and macrophages (CD68) (Figure 1). These experiments revealed clear coexpression of the strongly positive cell population with plasma cell markers, but not with other cells. Similar
double-staining was found using the control anti-FITC antibody, confirming nonspecific binding of rabbit immunoglobulins to synovial plasma cells, especially in RA.
Based on these results, we want to stress that rabbit
immunoglobulins may nonspecifically bind to plasma cells in
RA synovium. Therefore, the use of proper negative controls is
essential. Conceivably, some commercially available negative
controls are selected on the basis of negative staining and,
therefore, different controls should be included. It appears
likely that certain citrullinated proteins may be specifically
up-regulated in rheumatoid synovial tissue, whereas others
could be present in both RA and other arthritides. However,
rabbit anti–L-citrulline polyclonal antibody may not be the
most reliable antibody to detect citrullinated proteins in synovial tissue by immunohistology.
T. J. M. Smeets, BSc
Academic Medical Center/University of Amsterdam
Amsterdam, The Netherlands
E. R. Vossenaar
W. J. van Venrooij, PhD
University of Nijmegen
Nijmegen, The Netherlands
P. P. Tak, MD, PhD
Academic Medical Center/University of Amsterdam
Amsterdam, The Netherlands
1. Schellekens GA, de Jong BA, van den Hoogen FH, van de Putte
LB, van Venrooij WJ. Citrulline is an essential constituent of
antigenic determinants recognized by rheumatoid arthritis-specific
autoantibodies. J Clin Invest 1998;101:273–81.
2. Masson-Bessiere C, Sebbag M, Girbal-Neuhauser E, Nogueira L,
Vincent C, Senshu T, et al. The major synovial targets of the
rheumatoid arthritis-specific antifilaggrin autoantibodies are deiminated forms of the alpha- and beta-chains of fibrin. J Immunol
2001;166:4177–84.
3. Baeten D, Peene I, Union A, Meheus L, Sebbag M, Serre G, et al.
Specific presence of intracellular citrullinated proteins in rheumatoid arthritis synovium: relevance to antifilaggrin autoantibodies.
Arthritis Rheum 2001;44:2255–62.
4. Smeets TJ, Vossenaar ER, Kraan MC, van Mansum WAM, Raats
JM, van Venrooij WJ, et al. Expression of citrullin-containing
antigens in RA synovium. Arthritis Res 2001;3:A2.
5. Kraan MC, Haringman JJ, Post WJ, Versendaal J, Breedveld FC,
Tak PP. Immunohistological analysis of synovial tissue for differential diagnosis in early arthritis. Rheumatology 1999;38:1074–80.
DOI 10.1002/art.10474
Reply
To the Editor:
We thank Smeets et al for their comments on our
recent study, in which we investigated by immunohistochemistry the presence of citrullinated proteins in the synovial
membrane of 36 patients with RA and in 52 controls with
inflammatory or noninflammatory disease. Using a polyclonal
rabbit antibody, we observed the presence of positively staining
cells in 50% of the patients with RA but in none of the
controls. As clearly mentioned in the report, no positive
staining was seen with an isotype- and concentration-matched
control antibody (rabbit immunoglobulin fraction; Dako,
Glostrup, Denmark), the results were confirmed with another
antibody monospecific for proteins containing modified citrulline (1), double immunofluorescence showed no colocalization
with B cell and plasma cell markers, and positive staining with
the anticitrulline antibody was seen in both rheumatoid factor
(RF)–positive and RF-negative patients. Moreover, the anticitrulline reactivity colocalized with affinity-purified antifilaggrin autoantibodies.
In an independent study, Smeets et al tried to confirm
these results in 54 synovial biopsy samples, using one of the
antibodies used in the Ghent study. They concluded that
positive staining with the anticitrulline antibody was seen in
both RA (8 of 14) and control (11 of 40) synovia, and that
nonspecific staining with a control antibody was observed in
“several” RA patients. These results are clearly discrepant with
our observations and raise three questions. First, is positive
staining with the anticitrulline antibody specific for RA synovium? Second, what exactly does this antibody recognize?
Third, independent of the polyclonal rabbit antibody, is the
presence of citrullinated proteins specific for RA synovium?
In order to clarify the first question regarding the RA
specificity of the staining with the polyclonal rabbit anticitrulline antibody, we agreed to perform a collaborative study with
Smeets et al. Synovial sections obtained from 33 different
patients from Amsterdam were sent to Ghent for staining with
the anticitrulline antibody. We were blinded as to the diagnoses of the patients from whom the samples were obtained.
We observed anticitrulline-positive cells in 8 patients. After
staining and scoring, the sections were sent back to Amsterdam
and the diagnoses revealed: 19 sections were from patients
with RA, and 14 were from controls (psoriatic arthritis, ReA,
OA). All sections scoring positively for anticitrulline in Ghent
were from RA patients. Thus, anticitrulline staining was positive in 8 of the 19 RA patients and in none of the 14 controls.
LETTERS
These figures are in complete accordance with those in our
previous report, confirming that this staining is specific for RA
synovium and could thus be a novel diagnostic tool. Smeets et
al, whose colleagues previously explored the potential of
synovial histopathology in the diagnosis of undifferentiated
arthritis (2), reanalyzed the same sections, and, after exclusion
of “weakly positive cells” (judged as negative in Ghent),
confirmed our findings.
With regard to the second question, based on nonspecific staining in negative controls and on the results of doublestaining experiments in their own study (but not in our
collaborative study!), Smeets et al argue that the staining may
be attributable to nonspecific binding of polyclonal rat antibodies to synovial plasma cells (which implies that these
plasma cells are specifically present in RA synovium; for
example, RF-producing plasma cells). Although it is speculative to comment on only partially presented data (because of
questions such as, in how many RA patients was nonspecific
staining seen, was the nonspecific binding seen in all RA
patients that were scored anticitrulline positive and in none of
the anticitrulline-negative patients, was there any nonspecific
staining in the non-RA patients, was the anticitrulline staining
correlated with RF status and/or the presence of synovial
plasma cells?), we completely agree that staining with polyclonal rabbit antibodies may induce nonspecific binding to
plasma cells. Therefore, we included in our original study a
concentration-matched control polyclonal rabbit antibody: in
none of the control sections was there positive intracellular
staining as seen with the anticitrulline antibody. Moreover,
citrulline-positive cells were seen not only in the sublining but
also in the lining layer and in synovial cell cultures, which
makes the plasma cell hypothesis unlikely. As already mentioned, double stainings with plasma cell markers were negative, and positive anticitrulline staining was seen in both
RF-positive and RF-negative RA patients.
Of major importance, it must be clarified that in our
collaborative study with Smeets et al, we simultaneously
stained parallel sections with the same polyclonal rabbit control antibody that was used in our original study, and no
positive staining was seen. In contrast with the statement of
Smeets and colleagues, we did not perform stainings with the
irrelevant anti-FITC antibody nor any double staining in this
collaborative study. The fact that they are probably referring to
separate experiments performed in Amsterdam makes direct
comparison and interpretation most speculative. Therefore,
the hypothesis of nonspecific binding to RF-producing plasma
cells certainly deserves further attention but is, at present,
supported by only little hard evidence.
Finally, Smeets et al mention that it is likely that
certain citrullinated proteins may be specifically up-regulated
in rheumatoid synovial tissue, whereas others could be present
in both RA and other arthritides. Although we tend to agree
with this statement, there are at present only few published
data on this point (3). Masson-Bessiere et al indicate that
indeed several citrullinated proteins are present in RA synovium, of which the alpha and beta chains of fibrin are
selectively recognized by antifilaggrin autoantibodies (3).
However, it is not yet known which of these citrullinated
proteins are also present in non-RA inflamed synovium.
Therefore, the development and validation of new immunologic tools, such as the recombinant scFv monoclonal antibody
2827
against a cyclic citrullinated peptide mentioned by Smeets et
al, and further studies investigating the biochemical identity of
citrullinated proteins in synovium are mandatory.
In conclusion, based on results of a collaborative study
with Smeets et al, we want to confirm that positive staining
with the polyclonal rabbit anticitrulline antibody is specific for
RA synovium and should thus be explored as a new tool in the
early diagnosis of undifferentiated arthritis. Conversely, it is
clear that further biochemical characterization of the citrullinated proteins present in synovium of RA patients and inflammatory disease controls is needed to investigate their role in
the pathogenesis of the disease. We hope this debate will
stimulate other researchers to explore these two questions.
Dominique Baeten, MD, PhD
Eric M. Veys, MD, PhD
Filip De Keyser, MD, PhD
Ghent University Hospital
Ghent, Belgium
1. Senshu T, Akiyama K, Kan S, Asaga H, Ishigami H, Manabe M.
Detection of deiminated proteins in rat skin: probing with a
monospecific antibody after modification of citrulline residues.
J Invest Dermatol 1995;105:163–9.
2. Kraan MC, Haringman JJ, Post WJ, Versendaal J, Breedveld FC,
Tak PP. Immunohistochemical analysis of synovial tissue for differential diagnosis in early arthritis. Rheumatology 1999;38:1074–80.
3. Masson-Bessiere C, Sebbag M, Girbal-Neuhauser E, Nogueira L,
Vincent C, Senshu T, et al. The major synovial targets of the
rheumatoid arthritis-specific antifilaggrin autoantibodies are deiminated forms of the alpha- and beta-chain of fibrin. J Immunol
2001;166:4177–84.
DOI 10.1002/art.10525
Is acquired C1 inhibitor deficiency associated with
lupus a distinct disease entity? Comment on the
article by Cacoub et al
To the Editor:
We read with interest the recent report of acquired C1
inhibitor deficiency associated with systemic lupus erythematosus (SLE) (Cacoub P, Fremeaux-Bacchi V, De Lacroix I,
Guillien F, Kahn M, Kazatchkine M, et al. A new type of
acquired C1 inhibitor deficiency associated with systemic lupus
erythematosus. Arthritis Rheum 2001;44:1836–40). Cacoub et
al make an interesting, albeit unconvincing, case for a new type
of acquired C1 inhibitor deficiency. The case for a distinct
disease entity hinges on the temporal occurrence of angioedema in 3 patients with borderline low antigenic levels of C1
inhibitor (values ranging from 6 mg/dl to 8 mg/dl [normal
9–15]) on a background of hypocomplementemia.
Interestingly, C1 inhibitor functional activity is not
presented. As the authors state, hypocomplementemia due to
classical pathway activation is a frequent finding in SLE, and
the slight reduction in C1 inhibitor levels may reflect merely
complement activation rather than a primary abnormality. In
order to assess the true significance of the marginally low C1
inhibitor levels in these 3 patients, it is essential that C1
2828
LETTERS
inhibitor levels in SLE patients without angioedema be presented. Moreover, it is noteworthy that C1 inhibitor levels have
returned to normal in all 3 patients. The transient nature of
this apparent C1 inhibitor deficiency calls into question
whether this represents a distinct entity.
Patrice Cacoub, MD
Hôpital La Pitié-Salpêtrière
Véronique Frémeaux-Bacchi, MD
Hôpital Européen Georges Pompidou
Paris, France
Aamir Aslam, BSc, MRCP
Siraj A. Misbah, MSc, FRCP, FRCPath
John Radcliffe Hospital
Oxford, UK
1. Ochonisky S, Intrator L, Wechsler J, Revuz J, Bagot M. Acquired
C1 inhibitor deficiency revealing systemic lupus erythematosus.
Dermatology 1993;186:261–3.
2. Fawaz-Estrup F. Human parvovirus infection: rheumatic manifestations, angioedema, C1 esterase inhibitor deficiency, ANA positivity, and possible onset of systemic lupus erythematosus. J Rheumatol 1996;23:1180–5.
DOI 10.1002/art.10522
Reply
DOI 10.1002/art.10378
To the Editor:
We thank Aslam and Misbah for their comments on
the 3 cases illustrating a new type of acquired C1 inhibitor
deficiency. C1 esterase inhibitor deficiency is an uncommon
disorder characterized by recurrent episodes of angioedema
without urticaria. From a clinical point of view, the symptoms
resemble those seen in inherited or acquired C1 inhibitor
deficiency. The diagnosis of C1 inhibitor deficiency was based
on low plasma levels of C1 inhibitor antigen. At the time of
angioedema, the antigenic and functional levels of C1 inhibitor
were below normal in all patients (functional C1 inhibitor
activity was assessed using a chromogenic assay). Only 2 cases
of quantitative deficiency of C1 inhibitor antigen in patients
with SLE in the absence of angioedema have been reported
(1,2).
Part of our report described 3 SLE patients with
angioedema and low C1 inhibitor antigenic levels. A genetic
C1 inhibitor deficiency can be ruled out because there was no
quantitative or functional C1 inhibitor deficiency after steroid
treatment. These tests were repeated at least 4 times (2 months
apart) for all patients, and the results were consistently confirmed. Two forms of acquired angioedema have been previously described. Type I occurs in patients with lymphoproliferative disorders, with no detectable circulating antibodies to
C1 inhibitor. Type II acquired angioedema is characterized by
the presence of anti–C1 inhibitor antibodies and a circulating
low molecular weight, functionally inactive form of C1 inhibitor.
The search for a lymphoproliferative disorder or biologic evidence of type II acquired C1 inhibitor deficiency
yielded negative results in all 3 patients. In a patient with
typical angioedema and no evidence of type I or type II
acquired angioedema, the presence of major classical
pathway–mediated complement consumption, including low
levels of C3, suggests the third type of acquired angioedema,
and patients should be tested for systemic lupus. Although
acquired angioedema has been assumed to be related to
antigenic or functional deficiency of C1 inhibitor, a third type
exists that is associated with transient C1 inhibitor deficiency
and occurs in the context of autoimmune disease.
To the Editor:
We read with interest the report of Keen et al (1), who
demonstrated the relationship between a common polymorphic Sp1 binding site in the first intron of the COL1A1 gene,
bone mineral density (BMD), and bone remodeling. However,
discordant results have been reported (2,3).
Our intention was to determine whether Sp1 genotypes
are related to BMD, markers of collagen turnover, and ultrasound stiffness. We studied 108 postmenopausal Caucasian
women (mean ⫾ SD age 62.5 ⫾ 8.9 years), who underwent
measurement of BMD (gm/cm2) at the lumbar spine (L1–4)
and at the hip using dual x-ray absorptiometry. Stiffness of the
heel was assessed by ultrasound transmission measurement
(CUBA Clinical Contact Ultrasound Bone Analyzer; Cooper
Surgical, Lake Forest, CA). To investigate levels of collagen
turnover, carboxyterminal propeptide of type I procollagen
(PICP) and carboxyterminal telopeptide of type I collagen
(ICTP) were determined using a radioimmunoassay kit (Orion
Diagnostica, Helsinki, Finland). The Sp1 COL1A1 genotypes
were assessed as described by Grant et al (4). Polymerase chain
reaction was followed by endonuclease digestion with Mls I
(Fermentas, Vilnius, Lithuania). Fragments were separated on
3% agarose gel, and Sp1 genotypes were identified. Alleles
were coded as “S” (absence of restriction site) and “s”
(presence of restriction site).
There were no significant differences in anthropometric and environmental variables (age, body mass index [BMI],
years since menopause [YSM], calcium intake, or physical
activity) in the COL1A1 genotype subgroups. None of the
probands had been using hormone replacement therapy. Due
to the small number of subjects with the ss genotype, use of
analysis of covariance (ANCOVA) was inappropriate. Therefore, the ss genotype was excluded from the analysis. Differences in BMD, stiffness, and biochemical markers between the
SS and Ss genotype groups were evaluated by ANCOVA after
adjustment for the potential confounding effect of BMI and
YSM.
The COL1A1 genotype distributions were similar to
Is the Sp1 polymorphism in the COL1A1 gene a risk
factor for postmenopausal osteoporosis? Comment on
the article by Keen et al
LETTERS
2829
Table 1. Bone density, stiffness index, and biochemical markers of collagen turnover in relation to
COL1A1 genotypes*
Genotype
Variable
SS
Ss
ss
P, SS vs.
Ss†
BMD L1–4, gm/cm2
BMD total hip, gm/cm2
Stiffness index score
S-PICP, ␮g/liter
S-ICTP, ␮g/liter
0.85 (0.74–0.973)
0.76 (0.72–0.86)
66.6 (56.4–85.3)
122.3 (90.5–150.0)
2.81 (2.37–3.69)
0.85 (0.77–0.96)
0.76 (0.69–0.91)
74.8 (59.4–84.9)
122.8 (102.6–141.4)
3.19 (2.24–3.80)
0.9 (0.75–0.97)
0.75 (0.63–0.89)
60.4 (59.8–66.9)
146.65 (136.4–156.9)
4.07 (3.33–4.81)
0.87
0.67
0.86
0.62
0.53
*Values are the median (lower–upper quartile). S ⫽ absence of restriction site; s ⫽ presence of restriction
site; BMD ⫽ bone mineral density; PICP ⫽ carboxyterminal propeptide of type I procollagen; ICTP ⫽
carboxyterminal telopeptide of type I collagen.
† Values were determined by analysis of covariance of variables in SS and Ss genotypes.
those previously reported (1,4) and were in Hardy-Weinberg
equilibrium (P ⫽ 0.981): SS 65%, Ss 32%, and ss 3%. No
statistically significant differences were observed between the
SS and Ss genotype groups with regard to BMD at the lumbar
spine or hip. The stiffness index scores did not differ between
SS and Ss genotypes. No differences in either the marker of
collagen formation (PICP) or collagen degradation (ICTP)
were documented (Table 1).
Our results are consistent with those of some other
investigators (2,3) but contradict those of studies (5) that have
assumed the Sp1 polymorphism to be an independent marker
of increased bone fragility, regardless of BMD. The stiffness
index score, calculated from quantitative ultrasound, might
reflect bone quality. However, in the present study a significant
association between COL1A1 genotypes and stiffness was not
demonstrated. Some investigators (1,6) have reported that the
impact of COL1A1 genotypes on bone quality might be
mediated through impaired collagen metabolism. We failed to
confirm a relationship between indices of collagen turnover
(PICP, ICTP) and Sp1 genotypes.
This study has important limitations. It was conducted
with a limited sample of postmenopausal women. Neither
osteoporotic fractures nor rate of bone loss was investigated.
ANCOVA included only the SS and Ss genotypes. If, as has
been postulated, the s allele is associated with an increased risk
for reduced BMD and fracture (consistent with allelic dose–
response), Ss should represent a partially unfavorable genotype. In the present study, women with the ss genotype had
even higher BMD at the lumbar spine than did women with the
SS and Ss genotypes, which is not a unique finding (3).
In conclusion, the present data do not support the
hypothesis that the Sp1 polymorphism might contribute to
BMD, bone remodeling, or bone quality in postmenopausal
women.
Supported by research intention no. 000000023761 from the
Ministry of Health, Czech Republic.
K. Zajı́c̆ková, MD
I. Žofková, MD, PhD, DSc
M. Hill, PhD, DSc
Institute of Endocrinology
Prague, Czech Republic
1. Keen RW, Woodford-Richens KL, Grant SFA, Ralston SH, Lanchbury JS, Spector TD. Association of polymorphism at the type I
2.
3.
4.
5.
6.
collagen (COL1A1) locus with reduced bone mineral density,
increased fracture risk, and increased collagen turnover. Arthritis
Rheum 1999;42:285–90.
Lidén M, Wilén B, Ljunghall S, Melhus H. Polymorphism at the Sp
1 binding site in the collagen type I ␣ 1 gene does not predict bone
mineral density in postmenopausal women in Sweden. Calcif Tissue
Int 1998;63:293–5.
Heegaard A, Jorgensen HL, Vestergaard AW, Hassager C, Ralston
SH. Lack of influence of collagen type I ␣ 1 Sp1 binding site
polymorphism on the rate of bone loss in a cohort of postmenopausal Danish women followed for 18 years. Calcif Tissue Int
2000;66:409–13.
Grant SF, Reid DM, Blake G, Herd R, Fogelman I, Ralston SH.
Reduced bone density and osteoporosis associated with a polymorphic Sp1 binding site in the collagen type 1 ␣ 1 gene. Nat Genet
1996;14:203–5.
Weichetová M, Štěpán JJ, Michalská D, Haas T, Pols HA, Uitterlinden AG. COLIA1 polymorphism contributes to bone mineral
density to assess prevalent wrist fractures. Bone 2000;26:287–90.
Garnero P, Borel D, Grant SFA, Ralston SH. Sp1 binding site
polymorphism in the collagen type I alpha 1 gene, peak bone mass,
postmenopausal bone loss and bone turnover: the OFELY study
[abstract]. J Bone Miner Res 1997;12:S490.
DOI 10.1002/art.10487
Mutations of bone morphogenetic protein receptor
type II are not found in patients with pulmonary
hypertension and underlying connective tissue
diseases
To the Editor:
It has recently been reported that pleiomorphic heterozygous mutations in the gene encoding bone morphogenetic protein receptor type II (BMPR2) are a cause of familial
primary pulmonary hypertension (PPH) (1–4). BMPR2 is
located on chromosome 2q33, and the gene product is type II
transforming growth factor ␤ (TGF␤) receptor expressed in
many tissues, including the lung. The mechanism by which the
described mutations lead to abnormalities in the function of
this receptor and thus contribute to the development of PPH is
unclear, but mutations in BMPR2 are thought to lead to
proliferation of pulmonary arterial smooth muscle cells be-
2830
LETTERS
cause of ineffective transduction of Smad phosphorylation by
the mutant protein (5,6).
Pulmonary hypertension is a well-recognized complication of connective tissue diseases such as systemic sclerosis
(SSc) and systemic lupus erythematosus (SLE), and the histopathology of the pulmonary vascular lesions is very similar to
that seen in PPH (7,8). Therefore, we sought to determine if
mutations in BMPR2 were present in patients with pulmonary
hypertension and underlying connective tissue disease.
Genomic DNA was obtained from 12 patients with
connective tissue disease and pulmonary hypertension in the
absence of thromboembolic disease or pulmonary fibrosis.
Nine of the patients (6 Caucasian women, 1 African American
woman, 1 Hispanic woman, and 1 Caucasian man) met the
preliminary American College of Rheumatology (ACR; formerly, the American Rheumatism Association) criteria for SSc
(9). Two patients (both Hispanic women) met the ACR criteria
for SLE (10), and 1 Hispanic woman had been diagnosed with
mixed connective tissue disease based on the presence of
high-titer anti-RNP antibodies, myositis, Raynaud’s phenomenon, pulmonary hypertension, and the absence of criteria for
SSc or SLE. Each patient had documentation of pulmonary
hypertension by echocardiographic and/or invasive hemodynamic measurements with normal left ventricle function.
Thromboembolism and pulmonary fibrosis as causes of pulmonary hypertension were ruled out by history and physical
and radiographic examination. Genomic DNA from 10 healthy
volunteers having the same ethnicity as the patients was used
as controls. The 13 exons of BMPR2 were amplified and
directly sequenced using previously published primers (2). A
single-nucleotide polymorphism (SNP) was discovered in exon
12 at position ⫹2811 (G 3 A) coding for a silent mutation,
and its presence was confirmed by cloning and resequencing.
The Online Mendelian Inheritance in Man (OMIM)
database (http://www3.ncbi.nlm.nih.gov/Omim/) lists 17 allelic
variants of BMPR2 associated with PPH (OMIM 600799).
None of these allelic variants or mutations was found in our
pulmonary hypertension patients. Allele frequencies of the
SNP in exon 12 were identical among patients and controls.
The small size of this cohort is a potential limitation of this
study, but based on the previously reported frequencies of
BMPR2 mutations in sporadic cases of pulmonary hypertension of 25% (2,6), we would expect 3 members of our cohort to
carry BMPR2 mutations.
A similar study of a larger group of patients with
concomitant connective tissue disease and pulmonary hypertension would be very useful, especially if it were to evaluate
the presence of mutations in other TGF␤-related genes. The
fact that individuals affected by the same mutation within a
family manifest the disease at varying ages indicates that
environmental exposures or the interaction of other genes may
be important in pathogenesis of the disease (1–4). One possibility is that other proteins belonging to the TGF␤ superfamily
pathway may also be important in the pathogenesis of pulmonary hypertension in patients with connective tissue diseases.
These genes include endoglin and activin-receptor–like kinase
1, which have been implicated in PPH associated with hereditary hemorrhagic telangiectasias (11).
Supported by a grant from the LASR 2000 fund. Dr. Tan’s work
was supported by a grant from the NIH (NCRR-3M01-RR02558-1251).
Monty B. Tew, MD
Frank C. Arnett, MD
John D. Reveille, MD
Filemon K. Tan, MD, PhD
University of Texas Health Science Center
Houston, TX
1. Deng Z, Morse JH, Slager SL, Cuervo N, Moore KJ, Venetos G,
et al. Familial primary pulmonary hypertension (gene PPH1) is
caused by mutations in the bone morphogenetic protein receptor-II gene. Am J Hum Genet 2000;67:737–44.
2. Lane KB, Machado RD, Pauciulo MW, Thomson JR, Phillips JA
III, Loyd JE, et al. Heterozygous germline mutations in BMPR2,
encoding a TGF-␤ receptor, cause familial primary pulmonary
hypertension. Nat Genet 2000;26:81–4.
3. Machado RD, Pauciulo MW, Thomson JR, Lane KB, Morgan
NV, Wheeler L, et al. BMPR2 haploinsufficiency as the inherited
molecular mechanism for primary pulmonary hypertension. Am J
Hum Genet 2001;68:92–102.
4. Newman JH, Wheeler L, Lane KB, Loyd E, Gaddipati R, Phillips
JA III, et al. Mutation in the gene for bone morphogenetic protein
receptor II as a cause of primary pulmonary hypertension in a
large kindred. N Engl J Med 2001;345:319–24.
5. Loscalzo J. Genetic clues to the cause of primary pulmonary
hypertension. N Engl J Med 2001;345:367–71.
6. Scott J. Pulling apart pulmonary hypertension. Nat Genet 2000;
26:3–4.
7. Black CM, Dubois RM. Organ involvement: pulmonary. In:
Clements PL, Furst DE, editors. Systemic sclerosis. Baltimore:
Williams and Wilkins; 1996. p. 299–331.
8. Quismorio FP. Pulmonary manifestations of systemic lupus erythematosus. In: Wallace DJ, Hahn BH, editors. Dubois’ lupus
erythematosus. Baltimore: Williams and Wilkins; 1997. p. 673–92.
9. Subcommittee for scleroderma criteria of the American Rheumatism Association diagnostic and therapeutic criteria committee.
Preliminary criteria for the classification of systemic sclerosis
(scleroderma). Arthritis Rheum 1980;23:581–90.
10. Tan EM, Cohen AS, Fries JF, Masi AT, McShane DJ, Rothfield
NF, et al. The 1982 revised criteria for the classification of systemic
lupus erythematosus. Arthritis Rheum 1982;25:1271–7.
11. Trembath RC, Thomson JR, Machado RD, Morgan NV, Atkinson
C, Winship I, et al. Clinical and molecular genetic features of
pulmonary hypertension in patients with hereditary hemorrhagic
telangiectasia. N Engl J Med 2001;345:325–34.
DOI 10.1002/art.533
Erratum
In the article by Leask et al published in the July 2002 issue of Arthritis & Rheumatism (pp 1857–1865), the
name of the twelfth author, C. Bernabeu, PhD (Centro de Investigaciones Biologicas, Madrid, Spain) was
inadvertently omitted.
We regret the error.
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