Sodium chloride generates anti-inflammatory Th17 cell responses but amplifies Th17 cell pathogenicity in pro-inflammatory cytokine microenvironments

Abstract

Abstract Ionic signals have recently been demonstrated to affect T cell polarization and function. Sodium chloride (NaCl) was proposed to accumulate in peripheral tissues upon dietary intake and to promote autoimmunity via the Th17 cell axis. We here demonstrate that together with amplification of human Th17 cell signature properties, NaCl gave rise to a stable anti-inflammatory Th17 cell fate that we found to be restricted to distinct pathogen specificities. The p38/MAPK pathway involving NFAT5 and SGK1regulated FoxP3 and IL-17 expression in high NaCl conditions. The NaCl induced acquisition of an anti-inflammatory Th17 cell fate was confirmed in vivo in the mouse model of experimental autoimmune encephalomyelitis (EAE), which demonstrated strongly reduced disease symptoms upon transfer of NaCl-treated encephalitogenic Th17 cells. However, NaCl was coopted to promote murine and human Th17 cell pathogenicity, if T cell stimulation occurred in a proinflammatory and TGF-b low cytokine microenvironment. This revealed a context dependent dichotomous role for NaCl in shaping the pathogenicity of Th17 cells. NaCl might therefore prove beneficial for the treatment of chronic inflammatory diseases in collaboration with cytokine blocking drugs.