Pathological characteristics of skeletal muscle in anti-synthase syndrome patients / 中华风湿病学杂志

ABSTRACT

Objective:To investigate the pathological characteristics of skeletal muscle and its association with anti-aminoacyl-tRNA synthetases(ARS) antibodies and clinical features in patients with anti-synthetase syndrome (ASS).Methods:Patients diagnosed as ASS at China-Japan Friendship Hospital from 2008 to 2018 were involved in this study. Immunohistochemistry staining of MHC-Ⅰ, CD3, CD4, CD8 and CD20 molecule were performed in all muscle specimen taken from these patients. According to the muscular pathological characteristics, all patients could be divided into six pathological subgroups pathologic DM(pDM), pathologic PM (pPM), unspecified myositis(USM), necrotizing myopathies (NAM), only MHC-Ⅰexpression (MHC-Ⅰ) and normal pathology groups. Immunoblotting assay was used to detect anti-ARS antibodies. Statistical analysis was performed using Statistical Product and Service Solutions (SPSS) software. T-test, Mann-Whitney U test and Analysis of Variance (ANOVA) were used for the comparison of measurement data. Chi-square test or Fisher's test were used for categorical data. P<0.05 was considered statistically significant. Results:A total of 77 patients underwent muscle biopsy and anti-ARS antibodies test, with the average age of (50±12) years and disease course of 9(3-24) months. The prevalence of anti-Jo-1, anti-PL-7, anti-PL-12, anti-EJ and anti-OJ antibodies in these patients was 47%(36 cases), 29%(22 cases), 12%(9 cases), 13%(10 cases) and 0 respectively. Among all the ASS patients, the most common pathological type was USM(37/77, 48%), followed by pDM(14/77, 18%), the normal pathology(13/77, 17%), NAM(10/77, 13%) and MHC-Ⅰ (3/77, 4%) groups. There were no pPM subtypes in all groups. The frequency of pDM types was significantly different among the anti-ARS antibodies groups( χ2=9.075, P=0.028). The anti-EJ-positive patients had a higher frequency of pDM compared with anti-PL-7-group(40% vs 4%, χ2=6.555, P=0.024). Meanwhile, the CD20 expression in muscle tissue was observed in 30% of anti-EJ-positive patients and 4% of anti-Jo-1-positive ones. There was statistically significant difference in the positive rate of CD20 expression among anti-ARS antibodies groups ( χ2=12.837, P<0.01). Conclusion:The muscle pathological characteristics of ASS are polymorphic and relate to the anti-ARS antibodies. Performing muscle biopsy and distinguishing pathological types are helpful for the diagnosis and stratification of ASS.