Abstract

Dietary fibers are potent modulators of immune responses that can restrain inflammation in multiple disease contexts. However, dietary fibers encompass a biochemically diverse family of carbohydrates, and it remains unknown how different fiber sources influence immunity. In a head-to-head comparison of four different high-fiber diets, we demonstrate a unique and potent ability of guar gum to reduce neuroinflammation in experimental autoimmune encephalomyelitis (EAE), a T cell-mediated mouse model of multiple sclerosis. CD4+ T cells from guar gum-fed mice have blunted Th1-skewing, reduced migratory capacity, and limited activation and proliferative capabilities. These changes are not explained by guar gum-specific alterations to the microbiota at the 16S rRNA level, nor by specific alterations in short chain fatty acids. These findings demonstrate specificity in the host response to fiber sources, and define a new pathway of fiber-induced CD4+ T cell immunomodulation that protects against pathologic neuroinflammation.