The expression and significance of Th17 cell/regulatory T cells in peripheral blood of patients with idio-pathic inflammatory myopathy

Abstract

Objective To explore the expression and their significance of peripheral Th17 cells and regulatory T cells (Tregs) in idiopathic inflammatory myopathy, and analyze the relationship between the expression and clinical indicators, imaging and pathological changes. Methods Clinical data,laboratory tests, imaging and pathological changes of IIM cases (n=85) and healthy controls (n=70) were enrolled. Clinical data included the classification, age, gender, course of the disease; laboratory tests including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), creatine kinase (CK), creatine kinase isoenzyme-MB (CK-MB), lactate dehydrogenase (LDH), hydroxybutyrate dehydrogenase (HBDH). The level of peripheral Th17, Treg cells and clinical indicators, laboratory tests, imaging and pathological changes were analyzed retrospectively. Since the data was disregarded from the normal distribution, the median four quantile method was used for statistical description. Two samples were compared with Mann-Whitney U test, and the correlation between variables was Spearman rank correlation analysis. Results ① The levels of Th17 cells in the case group was not significantly different from that in the control group [6.18(3.42, 13.65) cell/μl vs 7.42(5.02, 11.13) cell/μl, P>0.05], the levels of Treg cells in patients was significantly lower than that in the control group [21.25(12.48, 35.67) cell/μl vs 36.95(30.37, 47.12) cell/μl, P 0.05). Peripheral Treg cells levels were negatively correlated with CRP (r=-0.279, P 0.05). ③ According to the involvement of important organs, patients were classified into two groups: organ involvement group and non-organ involvement group. The levels of Treg cells in the organ involvement group was fewer than that in non-organ involvement group [16.54(8.84, 27.34) cell/ul vs 24.87(14.44, 43.37) cell/ul, P 0.05). Conclusion The absolute number of peripheral Treg cells decreases significantly in IIM, and correlates with CRP. Patients with organ involvement have fewer Treg cells, and there is imbalance between Th17 and Treg. When muscle MRI presents with inflammatory edema, patients may have high level of Th17 cells. Our results suggest that Treg cells may play an important role in the pathogenesis of IIM. Key words: T-lymphocytes, regulatory; T-lymphocytes, helper-inducer; Idiopathic inflammatory myopathy; Inflammatory indicators; Magnetic resonance imaging; Muscle biopsy