Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose: Various autoantibodies associated with a unique subset of polymyositis/dermatomyositis (PM/DM), including antibodies to Jo-1 and other synthetases, SRP, Mi-2, PM-Scl and others, have been described. Specificities of autoantibodies and associated clinical manifestations in PM/DM are known to be affected by both genetic and environmental factors. In particular high prevalence of DM and anti-Mi-2 in Central America is thought to be associated with high UV index of the area. Prevalence of autoantibodies and clinical manifestation in PM/DM patients were evaluated comparing two cohorts in Mexico
Methods: Ninety-five Mexican patients with PM/DM (66 DM, 29 PM; 67 Mexico City, 28 Guadalajara) were studied. Autoantibodies recognized by sera were characterized based on protein analysis by immunoprecipitation using 35S-methionine labeled K562 cell extract and RNA analysis in immunoprecipitates by urea-PAGE and silver staining. Clinical information was from database and chart review.
Results:
DM was 69% in Mexican PM/DM and anti-Mi-2 was the most common autoantibody specificity (35%), followed by anti-p155/140 (11%); however, anti-Jo-1 that is the most common in most PM/DM studies was only 4%. DM was more common and comparable in both Mexico City and Guadalajara (69% and 71%, respectively). However, autoantibody profile in DM of Mexico City vs Guadalajara showed striking difference; anti-Mi-2 was 59% vs 15% (P = 0.001) whereas anti-p155/140 was 9% vs 30% (P = 0.05), respectively. Thus, despite comparable DM dominance and similar UV index in two areas, prevalence of anti-Mi-2 was very high (59%) in Mexico City but not in Guadalajara (15%), suggesting a role of factors other than UV. Reported differences in genetic background of Mexican-Mestizo in these two areas (higher percentage of Amerindian derived genes in Mexico City vs European derived gene dominance in Guadalajara area) may be related to the difference in prevalence of autoantibodies. Clinical feature of anti-Mi-2(+) DM (n = 30) vs anti-Mi-2(-) DM (n = 36) was compared. Male was more common in anti-Mi-2(+) vs (-) (37% vs 22%,P=0.27). Shawl sign (86% vs 62%, p=0.0002) and weight loss (59% vs 45%, p=0.30) were more common in anti-Mi-2(+) DM than anti-Mi-2(-) DM. High CPK (> 2000) (88% vs 35%, p= 0.0001) was more common in anti-Mi-2(+) and levels of muscle enzymes were higher in anti-Mi-2(+) group than anti-Mi-2(-) group (CPK p = 0.0001, LDH p = 0.001).
Conclusion: Anti-Mi-2 is at high prevalence in Mexican DM and associated with male, shawl sign, and high CPK. Prevalence of anti-Mi-2 and anti-p155/140 was significantly different in Mexico City vs Guadalajara, suggesting roles of factors other than UV in DM autoantibody production. Significant difference in clinical features of DM within a same country need to be carefully evaluated and the role of environmental and genetic factors will need further studies.
| PM/DM | DM |
DM Mexico City |
DM Guadalajara |
PM | |
| N= | 95 | 66 | 46 | 20 | 29 |
| Autoantibodies | |||||
| Mi-2 | 35% | 45% | 59%1 | 15%1 | 10% |
| p155/140 | 11% | 15% | 9%2 | 30%2 | 0% |
| Jo-1 | 4% | 3% | 4% | 0% | 7% |
| Myositis specific antibodies negative | 36% | 21% | 15% | 35% | 69% |
1, p=0.001; 2, p=0.056 by Fisher exact test
Disclosure:
M. Vazquez-Del Mercado,
None;
M. Petri,
None;
L. J. Jara-Quezada,
None;
M. A. Saavedra-Salinas,
None;
C. Cruz-Reyes,
None;
O. L. Vera-Lastra,
None;
L. Andrade,
None;
M. Salazar-Paramo,
None;
L. Gonzalez-Lopez,
None;
J. Gamez-Nava,
None;
R. E. Prieto-Parra,
None;
T. Martin Marquez,
None;
J. Y. F. Chan,
None;
E. K. L. Chan,
None;
M. Satoh,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/distinctive-characteristics-of-anti-mi-2-and-p155140-autoantibody-production-in-two-cohorts-of-mexican-patients-with-dermatomyositis/