Peptide directorySkin, immune & repair

HD-6

A defensin that does not kill but nets: it traps bacteria in self-made fibrils.

Where it comes from

Made in
Paneth cells, alongside HD-5
Sent out by
Into the crypt with HD-5
Acts on
  • Bacteria at the gut surface (Salmonella, Listeria, Yersinia)

What it does

  • Forms “nanonets” that entangle bacteria so they cannot reach the lining
  • Has almost no killing activity of its own
  • A second line behind HD-5

In medicine

  • No medicine. HD-6 falls with HD-5 in Crohn’s disease of the ileum, a research finding rather than a test 2
  • Its messenger RNA is used in research as the mark of a Paneth cell

Beyond the body’s own use

  • The nets are what is studied. HD-6 barely kills, and the 2012 work showing that it assembles into fibrils on bacterial surfaces, in mice as well as in the test tube, is a model for anti-infectives that trap rather than kill 1
  • How much it matters in a human crypt is not known: the living evidence comes from mice carrying the human gene, and the assembly depends on one particular histidine 1

Sources

  1. Chu et al., Human alpha-defensin 6 promotes mucosal innate immunity through peptide nanonets, Science 2012
  2. 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.