cryptdins

Cryptdins are a family of antimicrobial peptides produced by Paneth cells in the small intestine of several mammals, most notably mice. They belong to the defensin family, classed as alpha-defensins in rodents. Cryptdins are small, cationic, cysteine-rich peptides, typically around 3 to 4 kDa, stabilized by three disulfide bonds formed by six cysteine residues. They are stored in secretory granules of Paneth cells and released into the intestinal lumen in response to microbial cues.

In mice, cryptdins are encoded by multiple Defa genes and exist as several isoforms, commonly referred to by numbers such as cryptdin-1 through cryptdin-6 (and related variants). Expression is restricted largely to the small intestine, particularly the proximal and middle portions, and is influenced by the gut microbiota and inflammatory signals.

Cryptdins exert broad-spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria, certain fungi, and some viruses, primarily by binding and disrupting microbial membranes, leading to permeabilization and cell death. Beyond direct killing, they can modulate local immune responses, including chemokine production and neutrophil recruitment.

In animal studies, cryptdin expression contributes to the chemical barrier of the gut and helps shape the resident microbial community. Alterations in cryptdin expression or paneth cell function can affect susceptibility to enteric pathogens such as Salmonella and Listeria species. Cryptdins are studied for insights into host defense and as templates for designing novel anti-infective agents.

Related topics include other defensins and Paneth cells.