REG3A and irritable bowel syndrome: Kim et al. (2020) reported a link between melatonin and microbiota, demonstrating that bacterial sensing via TLR4, mucin, and Reg3 production by goblet cells was involved in the anti-colitic effects of melatonin, implying that melatonin may be useful in microbiota control and therapeutics for irritable bowel syndrome (IBD) [29].