It is well known that commensal microbiota interacts with cells o

It is well known that commensal microbiota interacts with cells of the intestinal mucosa via TLR [36] but not all bacteria have the ability to modulate immune responses, as this is a strain specific characteristic. As lactobacilli may be recognized by APCs through the peptidoglycan and lipoteichoic acid in their cell walls and/or CpG motifs in their DNA, we used anti-TLR2

and anti-TLR9 antibodies to block recognition via the respective receptors in order to elucidate whether they were responsible for the observed immunoregulatory activity of lactobacilli in APCs. TLR2 is one of the PRRs that would be of great importance for the immunomodulatory effect of probiotic microorganisms in APCs. Immunoenhancing lactobacilli are able to increase the expression of TLR2 in DCs and macrophages isolated from PPs in mice Talazoparib mouse [45] and in human myeloid DCs [46]. Moreover, Weiss et al.

[40] reported a TLR2-dependent mechanism for L. acidophilus NCFM, whose IFN-β expression was markedly reduced in TLR-2−/− DCs. In our experiments, the main effect observed on type I IFNs was observed in PIE cells and not in immune cells. After the challenge of APCs with poly(I:C), we observed a weak enhancement of type I IFNs mRNA expression, which was only 3 h after stimulation and therefore was not further studied. On the contrary, we observed a clear involvement of TLR2 signalling pathway in the up-modulation of IL-1β, IL-6, IL-10 and IFN-γ in APCs exerted by both L. rhamnosus strains alone and following a poly(I:C) challenge. In addition, the lactobacilli reported by Plantinga et al. [47] induced cytokines in DCs in a TLR9-dependent manner, contrasting our results which show no relationship between TLR9 and the immunoregulatory effect of Lr1505 or Lr1506. Chlormezanone Conclusions There is

a general concept that the overall effect of probiotics is strain-specific, but there are only a few comparative studies where at least two strains of the same species provide significant differences in their immunomodulatory potential [38]. Herein, we show that two strains, both L. rhamnosus, isolated from the same ecological niche and with similar technological properties [10, 11], are capable to induce differential antiviral defence phenotypes in IECs and APCs. We propose a model of action for each strain as depicted in Figure 7. In general terms, Lr1506 has a marked influence on IECs and antiviral innate defence mediated by type I IFNs, whereas Lr1505 stands out for its influence on APCs. Figure 7 Proposed mechanism for the immunoregulatory effect and antiviral activities of Lactobacillus rhamnosus CRL1505 and L. rhamnosus CRL1506 on porcine intestinal epithelial cells and antigen-presenting cells from swine Peyer’s patches.

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