T helper cells in synovial fluid of patients with rheumatoid arthritis primarily have a Th1 and a CXCR3+Th2 phenotype

Abstract Background The majority of CD4+ T helper (Th) cells found in the synovial fluid (SF) of patients with rheumatoid arthritis (RA) express CXCR3, a receptor associated with Th1 cells. In blood, subsets of Th2 and Th17 cells also express CXCR3, but it is unknown if these cells are present in RA SF or how cytokines from these subsets affect cytokine/chemokine secretion by fibroblast-like synoviocytes (FLS) from patients with RA. Methods We examined the proportions of Th1, Th2, CXCR3+Th2, Th17, CXCR3+Th17, Th1Th17, peripheral T helper (TPh) and T follicular helper (TFh) cells in paired SF and blood, as well as the phenotype of TPh and TFh cells in RA SF (n = 8), by the use of flow cytometry. We also examined the cytokine/chemokine profile in paired SF and plasma (n = 8) and in culture supernatants of FLS from patients with chronic RA (n = 7) stimulated with Th-associated cytokines, by the use of cytometric bead arrays and ELISA. Cytokine receptor expression in FLS (n = 3) were assessed by the use of RNA sequencing and qPCR. Results The proportions of Th1 and CXCR3+Th2 cells were higher in SF than in blood (P