The pronounced Th17 profile in systemic sclerosis (SSc) together with intracellular expression of TGFβ and IFNϒ distinguishes SSc phenotypes

Abstract

BACKGROUND. Systemic sclerosis (SSc) is an autoimmune disease where controversy on Th1/Th2 balance dominates. We investigated whether the recently discovered Th17 pattern was present in SSc. METHODOLOGY AND PRINCIPAL FINDINGS. Patients were subdivided as having limited cutaneous SSc (lcSSc, n=12) or diffuse cutaneous SSc (dcSSc, n=24). A further arbitrary subdivision was made between early dcSSc (n=11) and late dcSSc (n=13) based upon the duration of disease. As a comparator group 14 healthy controls were studied. CD3+ cells were isolated using FACS and subsequently studied for the expression of CD4, CD8, CD25, CD45Ro, CD45Ra, IL-23, GITR, CD69 and intracellular expression of IL-17, TGFβ and IFNϒ using flow cytometry. Levels of IL-17, IL-6, IL-1a and IL-23 were measured using Bioplex assays. SSc patients had more and more activated CD4+ cells. In addition, CD4, CD45Ro and CD45Ra cells from all SSc patients highly expressed the IL23R, which was associated with a higher IL-17 expression as well. In contrast, IFNϒ and TGFβ were selectively up regulated in SSc subsets. In line with these observation, circulating levels of IL-17 inducing cytokines IL-6, IL-23 and IL-1a were increased in all or subsets of SSc patients. CONCLUSION AND SIGNIFICANCE. The combination of IL-17, IFNϒ and TGFβ levels in CD45Ro and CD45Ra cells from SSc patients is useful to distinguish between lSSc, ldSSc or edSSc. Blocking Th17 inducing cytokines such as IL-6 and IL-23 may provide a useful tool to intervene in the progression of SSc.