Figure 1
Intestinal epithelial cells secrete CCL20 differentially in response to various bacteria. Confluent HT-29 cells were treated with Salmonella typhimurium (1 × 107 colony-forming units (CFU)/ml), flagellin (0.5 μg/ml), Clostridium difficile (1 × 107 CFU/ml), an equal volume of their cell-free culture supernatants, Mycobacterium paratuberculosis (1 × 108 CFU/ml), M. smegmatis (1 × 108 CFU/ml), Bifidobacterium infantis (1 × 107 CFU/ml), or Lactobacillus salivarius (1 × 107 CFU/ml). CCL20 protein levels in cell culture supernatants were measured after 6 hr, 12 hr, or 24 hr as specified on the above graph. Significant levels of CCL20 were only detected after 12 hr incubation with M. paratuberculosis and after 24 hr with C. difficile. M. smegmatis, B. Infantis and L. Salivarius did not result in significant CCL20 secretion at any of the time points or concentrations used. The data are expressed as pg/ml CCL20 and represent the mean ± standard error (n = 7 independent experiments). *P < 0.05 relative to untreated cells.