Treatment of chickens with lactobacilli prior to challenge with Clostridium perfringens modifies innate responses and gut morphology

Necrotic enteritis caused by Clostridium perfringens (CP), is a common enteric disease of poultry that has been previously controlled by in-feed antibiotics. However, due to the rapid emergence of antimicrobial resistance, alternatives to antibiotics such as probiotics have received considerable attention because of their immunomodulatory and intestinal health benefits. The present study investigated the effects of probiotic lactobacilli on gut histomorphology and intestinal innate responses in chickens. Day-old male broiler chickens were treated with 1 x 10 7 or 1 x 10 8 colony-forming units (CFU) of a lactobacilli cocktail on days 1, 7, 14, and 20 post-hatch, while control groups were not treated with lactobacilli. On day 21, birds in all groups (except the negative control) were challenged with 3 x 10 8 CFU of CP for 3 days. Intestinal tissue samples were collected before and after the CP challenge to assess gene expression and for histomorphological analysis. Lactobacilli treatment at a dose of 1 x 10 8 CFU conferred partial protection against NE by lowering lesion scores, increasing villus height in the ileum and reducing crypt depth in the jejunum. In addition, 1 x 10 8 CFU of lactobacilli enhanced the expression of Toll -like receptor (TLR) 2, interferon-gamma (IFN- gamma), interleukin (IL) -10, IL -12, and IL -13 in both the jejunum and ileum at different timepoints and subsequently decreased the expression of transforming growth factor beta (TGF-I3) and IL -1I3 post -CP challenge. In conclusion, the results indicate that treatment with lactobacilli mitigated NE in a dose -dependent manner via improvement of intestinal morphology and modulation of innate immune response in chickens.