Zinc Deficiency Reduces Intestinal Secretory Immunoglobulin A and Induces Inflammatory Responses via the Gut‐Liver Axis.

Nutritional zinc (Zn) deficiency could impair immune function and affect bowel conditions. However, the mechanism by which Zn deficiency affects the immune function of gut‐associated lymphoid tissue (GALT) remains unclear. We investigated how Zn deficiency affects the function of GALT and level of secretory IgA (sIgA), a key component of the intestinal immune barrier, its underlying mechanisms, and whether Zn deficiency induces bacterial translocation to the liver. As previous research has indicated that interleukin (IL)‐4 administration or Zn supplementation has a beneficial effect on the spleen of Zn‐deficient rats, we investigated whether these supplements reverse the GALT immune system. Five‐week‐old male rats were fed a standard diet, Zn‐deficient diet supplemented with saline or IL‐4 for 6 weeks, or Zn‐deficient diet followed by a standard diet for 4 weeks. Zn deficiency suppressed sIgA secretion in the intestinal tract by affecting GALT function and induced inflammatory responses through bacterial translocation to the liver via the portal vein. Furthermore, IL‐4 administration and Zn supplementation in rats with Zn deficiency elicited comparable beneficial effects on GALT function, suggesting that the administration of either IL‐4 or Zn could prevent inflammatory response via bacterial translocation to the liver. [ABSTRACT FROM AUTHOR]