The effect of lactobacillus fermentum on the activation of chicken TLR4 and defensins after infection by C. coli.

Campylobacter jejuni and C. coli are identified as major causes of food-borne disease in humans worldwide. Chicken TLRs are important in the recognition of PAMPs to induce the production of antimicrobial peptides and the expression of co-stimulatory molecules that may initiate adaptive immunity responses. Beta-defensins are antimicrobial peptides, which represent one family of host defence peptides that are modulated during campylobacter infection. On the other hand, it has been reported that campylobacter usually significantly downregulated their production. Promising therapy appears to be use of probiotic strains such as Lactobacillus spp. The aim of this study was to determine whether probiotic-feeding affected the expression of TLR4 and selected defensins (AvBD2, AvBD6) in response to C. coli challenge in the cecum of broilers. Forty one day-old broilers were randomly divided into 4 experimental groups (n= 10): control (C), L. fermentum CCM7514 (LB), C. coli (CJ), and combined L. fermentum CCM7514 + C. coli (LBCJ). L. fermentum was administered daily per os to LB and LBCJ groups from day 1 to day 7 of the experiment. C. coli was administered orally on day 4 of the experiment by a single dose to CJ and LBCJ groups. Samples from cecum were collected on day 4 and 7 post- Campylobacter infection (dpi). Samples were homogenized and total of RNA was isolated. Specific primers were used. Amplification and detection of specific products were performed using CFX 96 RT system with predefined program. Relative mRNA expression of defensins was upregulated in combined group compared to other groups (P<0.001) at 7 dpi. However, the increase relative expression of TLR4 was recorded in LB group compare to other groups (P < 0.05,P < 0.01,P<0.001) during both samplings. These results suggest that probioticsfeeding may stimulate the immunodefence system mediated by defensins and TLR4 against infection by C. coli in the cecum of broilers. [ABSTRACT FROM AUTHOR]