Mucus protectors: Promising therapeutic strategies for inflammatory bowel disease

Inflammatory bowel disease (IBD) is a group of intestinal non-specific inflammatory diseases with unclear pathogenesis, characterized with the impaired intestinal mucosal barriers and the activated immune system. Mucus layer is the vital protector over the intestinal epithelia cells (IECs). Mucus layer with impaired function could not provide isolated protection for IECs and thus proteases and pathogens from the gut lumen attacked and damaged the epithelial layer. Clinical manifestation and histopathology suggest that IBD might be a self-digestive inflammatory disease caused by digestive enzymes. In this review, we specifically focus on the role of intestinal mucosal barriers and aim to summarize the relationship among mucus layer, self-digestion and inflammation in IBD. We also propose a "Two Hits" Self-Digestion theory to explain the role of self-digestion in IBD and assess the application of mucus protectors to treat IBD.