Wang et al. [49] administered Bacillus coagulans (1 × 109 CFU) to SPF mice with dextran sulfate sodium-induced colitis and found that Bacillus coagulans could significantly upregulate the expression levels of colonic OCLN and mucin-2 mRNA, thereby enhancing the intestinal mucus layer and resists the invasion of microorganisms. The gene discussed is OCLN; the disease is colitis.