Water intake regulates mucosal immunity in rat jejunal villi via IL-1β, IL-6, and IL-10

We had demonstrated that the intragastric administration of distilled water increased male rat jejunal lymph flow and interleukin-22 levels in the lymph, resulting in the promotion of innate immunity. However, there is no information concerning whether the water intake regulates mucosal immunity in the jejunum of male rats. Based on the evidence, we investigated the effects of distilled water intake on gut immunity in the rat jejunum. Water intake significantly stimulated the release of IL-1β and IL-6 in mesenteric lymph. However, the concentration of IL-10 was not changed by water intake. Pretreatment with clodronate significantly decreased the lymph flow at 120-180 min after the intake. Clodronate significantly reduced water intake-mediated release of IL-1β and decreased, but not significantly, the release of IL-6. MyD88 inhibitor significantly decreased water intake-mediated release of IL-1β and IL-6. However, clodronate and MyD88 inhibitor did not significantly change IL-10 in the lymph. The expression levels of the macrophage markers CD68, F4/80, and CD169 in the jejunal villi significantly decreased due to pretreatment with clodronate. These findings suggest that water intake acts as a trigger for starting mucosal immunity in the jejunum via macrophage and MyD88-mediated activation of the release of IL-1β and IL-6.