Antigen-independent IL-17A production by bystander-activated CD4+IL-1R1+ cells in patients with Multiple Sclerosis

Abstract

Multiple sclerosis (MS) is a demyelinating disease caused by an autoantigen recognizing CD4+ T cells. However, IL-17A-producing CD4+ T cells that are bystander-activated by IL-1β and IL-23, and T cell receptors (TCR) independently, could contribute to experimental autoimmune encephalomyelitis. Here, we studied the differences in the frequency and function of bystander-activated CD4+ T cells in patients with MS. A significantly higher frequency of CD4+IL-1Rl+ T cells was found in memory cells than in naïve CD4+ T cells and in Th17/Th17.1 than in Th1/Th2 subtypes in both MS and healthy controls (HC). Following IL-1β and IL-23 stimulation, IL-1Rl expression was markedly increased in both memory and Th17/Th17.1 cells, and their IL-17A-production was increased after bystander activation, which was significantly higher in MS compared with HC. Our study suggests a potential role of IL-17A-producing bystander-activated CD4+IL-1Rl+ T cells in MS.