Quantitative T cell subsets profile in peripheral blood from patients with idiopathic inflammatory myopathies: Tilting the balance towards proinflammatory and pro-apoptotic subsets

Abstract

The role of T cells in idiopathic inflammatory myopathies (IIM) is not yet clear. Some alterations in certain subsets have been reported in inflamed muscle cells. However, a broad quantitative assessment of peripheral T cell subsets has not been evaluated. The aim of this study was to address the quantitative profile of potential pathogenic T cell subsets, namely follicular helper T cells (Tfh), T helper type 17 (Th17), CD28null and regulatory T cells (Tregs) in peripheral blood from IIM patients. Thirty IIM patients and 30 age- and gender-matched healthy donors were included. Peripheral blood mononuclear cells were isolated. T cell subsets were evaluated by flow cytometry, as follows: Tfh (CD4+CXCR5+) and its subsets Tfh1 (CXCR3+CCR6-), Tfh2 (CXCR3-CCR6-), Tfh17 (CXCR3-CCR6+), Th17 (CD4+IL17A+), CD28null (CD4+CD28-CD244+) and Tregs (CD4+CD25highforkhead box protein 3 (FoxP3+); CD8+CD25highFoxP3+). Percentage, absolute numbers and mean fluorescence intensity were analysed. We found increased numbers of total Tfh cells (28±8·16 versus 6·64±1·29, P=0·031) in IIM patients when compared to healthy controls. Moreover, this increment was dependent upon Tfh2 and Tfh17 (Tfh2:9·49±2·19 versus 1·66±0·46, P=0·005; Tfh17 9·48±2·83 versus 1·18±0·21, P=0·014). Also, IIM patients showed higher numbers of Th17 cells (30·25±6·49 versus 13·46±2·95, P=0·031) as well as decreased number of Tregs (5·98±1·61 versus 30·82±8·38, P=0·009). We also found an expansion of CD28null cells (162·88±32·29 versus 64±17·35, P=0·015). Our data suggest that IIM patients are characterized by an expansion of peripheral proinflammatory T cells, such as Tfh and Th17, as well as pro-apoptotic CD28 null cells and a deficiency of suppressor populations of Tregs (CD4+ and CD8+).