Advances in Mucosal Immunology pp 251-255
Cryptdins: Endogenous Antibiotic Peptides of Small Intestinal Paneth Cells
Despite its nutrient-laden content, only a sparse microbial flora persists within the small intestine’s lumen. How the small intestine controls microbial populations at its critical sites of food absorption and epithelial cell renewal is poorly understood, but multiple factors are likely to contribute. Traditionally, these are believed to include the effects of gastric acidity on organisms that enter it via the oral cavity, the combined mechanical effects of peristalsis and epithelial cell shedding, and possibly the antimicrobial effects of various detergent-like bile salts, fatty acids and lysolipids. A recent report that murine small intestinal Paneth cells contained mRNA encoding a peptide, “cryptdin”,1 that was homologous to the antimicrobial defensins2 found in many mammalian phagocytes, raised the possibility that endogenous antibiotic peptides might also mediate innate small-intestinal resistance to colonization and infection. Because these intestinal defensins had not previously been isolated and tested for antimicrobial activity, we undertook the studies described below.
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