Division of Connective Tissue Disease and Autoimmunity, Department of Dermatology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
Arthritis Res Ther. 2011;13(6):R214. doi: 10.1186/ar3547. Epub 2011 Dec 22.
Several reports have found the onset or activity of inflammatory myopathies to show spatial clustering and seasonal association. We recently detected autoantibodies against melanoma differentiation-associated gene 5 (MDA-5) in more than 20% of patients with dermatomyositis. Anti-MDA-5 antibodies were associated with the presence of rapidly progressive interstitial lung disease in clinically amyopathic dermatomyositis (CADM). The present study aims to assess the growing prevalence of CADM and the geographical incidence of anti-MDA-5-positive patients.
We reviewed medical charts and examined the presence of anti-MDA-5 antibodies in 95 patients, including 36 CADM patients. Sera were obtained from 1994 through 2011. Statistical analyses were performed to assess whether CADM development and the presence of anti-MDA-5 antibodies were associated with various parameters, including age at disease onset, season of onset, annual positivity, and population of resident city.
Tertiles based on the year when the sera were collected showed increasing tendencies of CADM and anti-MDA-5-positive patients among all of the dermatomyositis patients. From 1994 to 2010, the relative prevalence of CADM and anti-MDA-5 antibody-positive patients significantly increased. Interestingly, the presence of anti-MDA-5 antibodies in 26 patients was inversely associated with the population of their city of residence.
This is the first study to examine the distribution of anti-MDA-5-positive dermatomyositis phenotypes in Japan. Regional differences in the incidences of these phenotypes would suggest that environmental factors contribute to the production of antibodies against MDA-5, which triggers innate antiviral responses.
多项报告发现，炎症性肌病的发病或活动呈现空间聚集性和季节性关联。我们最近在超过 20%的皮肌炎患者中检测到抗黑色素瘤分化相关基因 5（MDA-5）自身抗体。抗 MDA-5 抗体与临床无肌病性皮肌炎（CADM）中快速进展性间质性肺病的存在相关。本研究旨在评估 CADM 的患病率增长情况以及抗 MDA-5 阳性患者的地理发病率。
我们回顾了病历，并在 95 名患者中检查了抗 MDA-5 抗体的存在情况，其中包括 36 名 CADM 患者。血清采集自 1994 年至 2011 年。进行统计学分析以评估 CADM 发展和抗 MDA-5 抗体的存在是否与各种参数相关，包括发病年龄、发病季节、年阳性率和常住城市的人口。
基于收集血清的年份进行三分位数分析显示，在所有皮肌炎患者中，CADM 和抗 MDA-5 阳性患者的比例呈上升趋势。1994 年至 2010 年，CADM 和抗 MDA-5 抗体阳性患者的相对患病率显著增加。有趣的是，26 名患者中存在抗 MDA-5 抗体与他们居住城市的人口呈负相关。
这是首次在日本检查抗 MDA-5 阳性皮肌炎表型的分布情况。这些表型发病率的地域差异表明，环境因素可能导致抗 MDA-5 抗体的产生，从而触发先天抗病毒反应。
