2019 Volume 33 Issue 3 Pages 129-135
Antimicrobial peptides are major effectors of the innate immunity of multicellular organisms including human and play a critical role in host defense, and their importance has been widely recognized. The epithelium of the intestine is the largest surface area exposed to the outer environment including pathogens, commensal microbiota and foods. The Paneth cell lineage of intestinal epithelial cells produces and secretes α-defensin, an antimicrobial peptide, and functions in innate enteric immunity by removing pathogens. It also contributes to intestinal homeostasis through symbiosis with commensal microbiota. α-Defensin has selective activities against bacteria, eliciting potent microbicidal activities against pathogenic bacteria; however, it elicits minimal or no bactericidal activity against commensal bacteria. Therefore, α-defensins regulate the composition of the intestinal microbiota in vivo and play a role in homeostasis of the entire intestine. Recently, relationships between dysbiosis, abnormal composition of the intestinal microbiota, and diseases such as inflammatory bowel disease, and lifestyle-related diseases including obesity and atherosclerosis have been reported. However, the details of these mechanisms are still unknown. Because α-defensins regulate the composition of the intestinal microbiota, Paneth cells and their α-defensins may play a key role in linking microbiota and disease.
