Toll-like receptor 2-mediated induction of avian β-defensin 9 by Lactobacillus rhamnosus and its cellular components in chicken intestinal epithelial cells

ABSTRACT This study aimed to investigate the effects of probiotic Lactobacillus rhamnosus MLGA and its cell wall components on the induction of avian β-defensin 9 (AvBD9) expression in intestinal epithelial cells (IECs) from chicken embryos and to elucidate the underlying mechanism. Chicken IECs were stimulated with L. rhamnosus MLGA or cell wall components. Quantitative RT-PCR analysis was used to determine the expressions of target genes. L. rhamnosus MLGA and its cellular components significantly induced AvBD9 and TLR2 expression, with the whole peptidoglycan (WPG) being the most potent inducer. Pretreatment of chicken IECs with a TLR2 neutralizing antibody diminished AvBD9 induction by L. rhamnosus MLGA and WPG. The inhibition tests showed that induction of AvBD9 in IECs by L. rhamnosus MLGA and WPG was dependent on NF-κB or JNK pathways. These results demonstrate that L. rhamnosus MLGA and WPG induce AvBD9 expression in chicken IECs via a TLR2-mediated NF-κB/JNK pathway