Meat proteins in high-fat diet have a substantial impact on intestinal barriers through mucus layer and tight junction proteins suppression in C57BL/6J mice

Protein diets are well known for body maintenance and weight loss. However, it remains unclear whether and how different proteinsources affect the intestinal epithelial integrity through tight junctions, mucus secretions and host immunity in diet-induced obesity. To evaluate possible impacts, soybean, chicken and pork proteins either with low-fat (12% Kcal) or high-fat (60% Kcal) were administered to C57BL/6J mice for 12 weeks. Muc2 expression, tight junction proteins, goblet cells, and inflammatory cytokines in colon and serum were measured. Intake of high-fat pork protein diet decreased number of goblet cells and inhibited Muc2 expression in colon, which impaired mucus barrier. Immunohistochemistry indicated decreased crypt depth and downregulation of tight junction proteins in high-fat diet fed mice signifying losses of epithelial barriers. In addition, pork protein diet reduces the key zonulaoccludens-1 and E-cadherin proteins. High-fat meat protein diet induces colonic inflammatory injury by upregulating several key cytokines along with elevation in IL-1β, TNF-ɑ, IL-6 and IFN-ɤ concentrations in serum. Intake of high-fat meat protein diets resulted in impairment of colon barrier through mucus suppression, down-regulation of tight junctions, and gut inflammation in mice.