AB0686 REDUCTION IN THE ABSOLUTE NUMBER OF PERIPHERAL REGULATORY T CELLS CORELATED TO CLINICAL FEATURES IN PATIENTS WITH SYSTEMIC SCLEROSIS

Background:The role of regulatory T cells (Tregs) in the development of SSc has started being studied during the last decade with new aspects being disclosed continuously. Although there is a general agreement in the medical literature regarding the decreased functional capacity of circulating Tregs in SSc, the alteration of absolute number of Treg and Th17 cells as well as their associations with clinical characteristics of SSc are still unclear.Objectives:The present study was to investigate the relationship between multiple system impairments, disease activity and the absolute number of CD4+CD25+FOXP3+ regulatory T cells (Treg cells) and interleukin 17 producing T help cells (Th17) in peripheral blood of patients with systemic sclerosis (SSc).Methods:Clinical indicators were collected from total 54 patients with SSc[8 with localized SSc (lcSSc) and 46 with diffuse SSc (dcSSc)] who were divided into two groups, mainly with skin lesions (n=11) and with multiple system and organ besides skin lesions (n=43). Then according to the SSc EUSTAR index, we divided 54 SSc patients into the inactive (EUSTAR < 2.5 points, n = 22 cases) and the active group (EUSTAR score ≥ 2.5 points, n = 32 cases). The levels of peripheral T lymphocyte were detected with flow cytometry.Results:We found that SSc, especially dcSSc patients, had significantly fewer peripheral CD4Treg cells (both absolute number and proportion, p<0.01) than healthy controls (Figure 1). In addition, the absolute number of peripheral Treg cells was significantly reduced in SSc patients with multiple system impairments (P<0.001), however, the number of Th17 cells were significantly increased in SSc patients with simple skin involvement (P = 0.002) (Figure 2). Also the absolute number of peripheral CD4Treg cells in active group with SSc decreased more significantly, thus causing an increase in the ratio of Th17 and Treg cells (Figure 2).Conclusion:The reduced absolute number of peripheral Treg cells in SSc patients was contributed to the imbalance of Th17/Treg cells and involved in the pathogenesis of SSc, and may promote multiple system impairments and disease activity.References[1] Liu M, Wu W, Sun X, et al. New insights into CD4(+) T cell abnormalities in systemic sclerosis. Cytokine Growth Factor Rev. 2016Apr; 28:31-6. doi: 10.1016/j.cytogfr.2015.12.002. [2] Lee GR. The Balance of Th17 versus Treg Cells in autoimmunity. Int J Mol Sci. 2018Mar3;19(3). pii: E730.doi: 10.3390/ijms19030730.Disclosure of interests:None declared