ACR Meeting Abstracts

ACR Meeting Abstracts

Abstract Number: 223

High Prevalence and Clustering Over Time of Anti-PL-7 Autoantibody-Positive Idiopathic Inflammatory Myopathies

Yoshioki Yamasaki1, Minoru Satoh2, Hidehiro Yamada1, Machiko Mizushima1, Takahiro Okazaki1, Hiroko Nagafuchi1, Seido Ooka3, Tomohiko Shibata1, Hiromasa Nakano4, Hitoshi Ogawa1, Kohei Azuma1, Akihiko Maeda1, Hirofumi Mitomi1, Tomofumi Kiyokawa1, Kosei Tsuchida1, Hidenori Mikage1, Jason Y.F. Chan2 and Shoichi Ozaki1, 1Internal Medicine, St. Marianna University School of Medicine, Kawasaki, Japan, 2Medicine, University of Florida, Gainesville, FL, 3St. Marianna University School of Medicine, Kawasaki, Japan, 4Division of Rheumatology and Allergy, Department of Internal Medicine, St. Marianna University School of Medicine, Kawasaki, Japan

Meeting: ACR/ARHP Annual Meeting 2012

Keywords:

Session Information

Title: Muscle Biology, Myositis and Myopathies: Clinical and Therapuetic Aspects of Idiopathic Inflammatory Myopathies

Session Type: Abstract Submissions (ACR)

Background/Purpose:  Unusually high prevalence of autoantibodies to threonyl tRNA (PL-7) [17% in polymyositis/dermatomyositis (PM/DM) associated with lower levels of serum creatine kinase (CK) and milder muscle weakness (vs. anti-Jo-1 positive patients)] was found in our study 8 years ago. We extended and analyzed a larger population of patients with PM/DM to further clarify the clinical characteristics of patients with anti-PL-7 antibodies. 

Methods:  The diagnosis of PM/DM and clinically amyopathic DM (cADM) was based on the Bohan and Peter criteria and modified Sontheimer’s criteria, respectively. Autoantibodies in sera from 97 Japanese patients with PM/DM (36PM/57DM/4cADM) were characterized by immunoprecipitation of K562 cell extract. Antibodies to Jo-1, melanoma differentiation-associated gene (MDA) 5, and Mi-2 also were tested by ELISA. Clinical and laboratory data were retrospectively collected.

Results:  The prevalence of autoantibodies to aminoacyl tRNA synthetases (ARS) such as histidyl (Jo-1) (22%), glycyl (EJ) (4%), isoleucyl (OJ) (1%), and alanyl tRNA synthetase (PL-12) (1%), and autoantibodies to Ku (7%), p155/140 (5%), SRP (4%), and Mi-2 (3%) was similar to other studies. However, prevalence of anti-PL-7 was unusually high (12%, 12/97) in contrast to other studies showing a prevalence of up to 4% (p <0.05 by Fisher exact test) consistent with our previous report. Notably, disease onset of patients with anti-PL-7 was either before 1993 or after 2002 and none between 1994-2001 whereas onset years of patients with anti-Jo-1 was distributed throughout (Table 1). 

Table 1. Prevalence of autoantibodies to PL-7 and Jo-1 according to year of onset.
Year 90-93 94-97 98-01 02-05 06-09 10-12
n 6 5 13 19 39 15
Anti-PL-7 (%) 50 0 0 16 10 13
Anti-Jo-1 (%) 17 60 23 11 23 20

Interstitial lung disease (ILD) was common in all anti-ARS-positive patients. Manual muscle testing (MMT) (total score of 90) <80 was only in 10% of anti-PL-7 group vs. 35% in anti-Jo-1 group, CK >3000 IU/l was 17% in anti-PL-7 vs. 57% in anti-Jo-1 (p <0.05 by Fisher exact test) (Table 2). 

Table 2. Frequency of ILD and severity of muscle involvement in patients with anti-ARS antibodies (vs. patients with no anti-ARS antibodies).

Autoantibodies

(n)

PL-7

(12)

EJ

(4)

Jo-1

(21)

ARS (-)

(57)

P
ILD (%) 92a 100a 100a 49 a<0.05 vs. ARS (-)

MMT (max 90) (SD)

 <80 (%)

85 (5)

10b

90 (0)

0

81 (10)

35

81 (10)

40

b<0.1 vs. ARS (-)

Serum CK IU/l

(IQR)

 <200 IU/l (%)

 >3000 IU/l (%)

942

(360-2679)

8

16

715

(246-1308)

25

0

3726c

(756-5534)

5d

57e

606

(181-1807)

25

14

c<0.1 vs. PL-7

c<0.05 vs. ARS (-)

d<0.1 vs. ARS (-)

e<0.05 vs. PL-7

e<0.1 vs. EJ

Conclusion:  Persistently high prevalence of anti-PL-7 antibodies was observed in this cohort, however, there was a ~10 year period when anti-PL-7 was not observed, suggesting roles of environmental factors. Muscle involvement was milder in patients with anti-PL-7 and EJ vs. anti-Jo-1.

Disclosure:

Y. Yamasaki,
None;

M. Satoh,
None;

H. Yamada,
None;

M. Mizushima,
None;

T. Okazaki,
None;

H. Nagafuchi,
None;

S. Ooka,
None;

T. Shibata,
None;

H. Nakano,
None;

H. Ogawa,
None;

K. Azuma,
None;

A. Maeda,
None;

H. Mitomi,
None;

T. Kiyokawa,
None;

K. Tsuchida,
None;

H. Mikage,
None;

J. Y. F. Chan,
None;

S. Ozaki,
None.

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