In rats, a similar reduction in ZO-1, intestinal permeability, steatosis, and fibrosis was observed in the choline-deficient/L-amino-acid-defined NASH diet, and was significantly attenuated by probiotic treatment with Clostridium butyricum MIYAIRI 588 strain. The gene discussed is TJP1; the disease is metabolic dysfunction-associated steatohepatitis.