Where it comes from
- Made in
- Paneth cells at the base of the small intestine’s crypts; also the female genital tract
- Sent out by
- Into the crypt lumen when bacteria or their products touch the Paneth cell, and on cholinergic signals
- Acts on
- Gut bacteria, including Salmonella and Listeria
- Fungi
- The toxin of C. difficile
What it does
- Keeps the crypt and the stem cells there nearly sterile
- Shapes which bacteria live in the small intestine
- Falls in ileal Crohn’s disease, which is one theory of that illness
In medicine
- Low HD-5 is a research finding in Crohn’s disease of the ileum, where the Paneth cell defensins fall together 3
- No medicine; HD-5 in the gut is measured only in research
Beyond the body’s own use
- Mice given the human gene in their Paneth cells survived an oral dose of Salmonella that killed ordinary mice, the clearest evidence that one peptide can set which bacteria take hold 2
- Oral analogues are studied in animals for C. difficile and for the gut barrier; nothing has been tested in people
Sources
- Jones & Bevins, Paneth cells of the human small intestine express an antimicrobial peptide gene, Journal of Biological Chemistry 1992
- Salzman et al., Protection against enteric salmonellosis in mice expressing a human intestinal defensin, Nature 2003
- Wehkamp et al., Reduced Paneth cell alpha-defensins in ileal Crohn’s disease, Proceedings of the National Academy of Sciences 2005
This card describes what a medicine is for and what the evidence says; it recommends nothing. Talk to your clinician about anything you read here.