Probiotic E. coli treatment mediates antimicrobial human beta-defensin synthesis and fecal excretion in humans

Mucosal Immunol. 2009 Mar;2(2):166-72. doi: 10.1038/mi.2008.77. Epub 2008 Nov 26.


Inducible epithelial human beta-defensins (hBD) play an important role in intestinal barrier function. In vitro studies showed that clinically effective probiotics induce antimicrobial hBD-2. Here, we aimed to assess the in vivo effect in healthy volunteers and also addressed how defensins affect probiotic survival. Symbioflor 2 containing one strain of several viable genotypes of Escherichia coli was administered to 23 healthy individuals. After 3 weeks, fecal hBD-2 peptide was increased in 78% (mean 3.7-fold; P<0.0001). Interestingly, the fecal hBD-2 peptide was still elevated 9 weeks after treatment (P=0.008). In vitro studies revealed that this effect was mediated by only one out of three tested E. coli genotypes and comparable to probiotic E. coli Nissle 1917 (10- to 15-fold). Functional assays showed that all tested bacteria were similarly killed by defensins allowing to speculate about a suicidal character of this effect. Defensin induction seems to be a common and important mechanism of probiotic treatment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Anti-Bacterial Agents / therapeutic use
  • Caco-2 Cells
  • Escherichia coli / drug effects
  • Escherichia coli / physiology*
  • Feces / chemistry*
  • Humans
  • Microbial Viability / drug effects
  • Probiotics / pharmacology*
  • Probiotics / therapeutic use
  • Species Specificity
  • beta-Defensins / metabolism*


  • Anti-Bacterial Agents
  • DEFB4A protein, human
  • beta-Defensins