The Role of Sodium Chloride and the Treg/Th17 Axis in Autoimmune Hepatitis

The etiology of autoimmune hepatitis (AIH) is unknown although both genetic and environmental factors are thought to be involved. A defect in immune regulation affecting regulatory T cells (Tregs) has been demonstrated in AIH. Tregs function in the maintenance of immune homeostasis by controlling autoreactive immune responses to self-antigens.

Rationale: the western diet has been postulated as a potential environmental risk factor for the increasing incidence of autoimmune diseases in developed countries. Data from the investigators' laboratory also suggests that increased dietary salt intake might represent an environmental risk factor for the development of autoimmune diseases through the induction of pathogenic Th17 cells. The dramatic in vitro effects of high salt on the induction of pathogenic Th17 cells from naïve human CD4 cells {Kleinewietfeld, Hafler. Nature. 2013 Apr 25;496(7446):518-22. doi: 10.1038/nature11868.}, and block of in vitro Treg suppression, in line with in vivo effects on worsening murine experimental autoimmune encephalomyelitis (EAE), have prompted the investigators to examine the effects of increased dietary sodium chloride in a human in vivo system.

The investigators hypothesize that excess dietary salt may function as an environmental trigger that favors induction and expansion of pathogenic Th17 cells and leads to functional impairment of Tregs, thereby favoring development of autoimmunity. The investigators aim to study their established in vitro model in humans by altering the salt intake in patients over a 20-day period.