Gut defence

摘要

The severity of salmonella infections depends in part on how effectively the invaders are destroyed. Incisive experiments now show that host defence in the intestine centres on the aptly named defensins. Cells that are engaged in the antimicrobial defence of mammals and birds produce defensins, a family of structurally related antimicrobial molecules. The production of similar small proteins is also often induced by infections in invertebrates and plants. Because of their abundance in infected tissues and their ability to kill a variety of microbes under laboratory conditions, defensins are thought to function as natural antibiotics. Until now, however, the evidence for their contribution to antimicrobial defence in living mammals was entirely circumstantial. That changes with the appearance of the paper by Salzman et al. on page 522 of this issue. The authors report that they performed a genetic transplant of human defensin 5 (HD-5) into mice and observed a dramatic improvement in the resistance of the mice to intestinal infection with Salmonella typhimurium.