Increased salt exposure affects both lymphoid and myeloid effector functions, influencing innate‐associated disease but not T‐cell‐associated autoimmunity

Summary High salt consumption has since long been associated with elevated blood pressure and cardiovascular disease. Recently, mouse studies suggested that a high dietary salt intake exacerbates the clinical manifestations of autoimmunity. Using naïve cells ex vivo after pre‐exposure of mice to high salt intake, we showed that increased salt exposure affects the viability and effector functions of immune cells. CD 4 + T‐cells evidenced a pro‐inflammatory phenotype characterized by increased secretion of IFN γ and IL ‐17A, when exposed to high salt concentrations in vitro . Interestingly, this phenotype was associated with osmotic pressure, as replacing salt for d ‐mannitol resulted in similar observations. However, high salt intake did not alter the development of T‐cell‐dependent autoimmunity. Instead, recruitment of peritoneal macrophages was increased in mice pre‐exposed to high salt concentrations. These cells had an increased production of both TNF α and IL ‐10, suggesting that salt stimulates expansion and differentiation of different subsets of macrophages. Moreover, mice pre‐exposed to high salt intake developed exacerbated symptoms of colitis, when induced by dextran sulphate sodium. The aggravated colitis in salt‐exposed animals was associated with a higher frequency of CD 4 + T‐cells and CD 11b + CD 64 + macrophages producing TNF α . These phenotypes correlated with elevated titres of faecal IgA and higher lymphocytic cellularity in the colon, mesenteric lymph nodes and spleen. In conclusion, we report here that high salt intake affects both lymphoid and myeloid cells ex vivo . However, the effects of high salt intake in vivo seem less pronounced in terms of CD 4 + T‐cell responses, whereas macrophage‐dependent pathologies are significantly influenced.