CLDN1 and metabolic dysfunction-associated steatotic liver disease: Our findings are consistent with previous studies that showed that HFD-feeding increases intestinal permeability by impairing tight junction protein function, such as a decrease in ZO-1 and Claudin-1 protein expression in the NAFLD (55, 56), and probiotic supplementation improves the expression of ZO-1 in the intestine (41).