Modulation of Macrophages TLR4-Mediated Transcriptional Response by Lacticaseibacillus rhamnosus CRL1505 and Lactiplantibacillus plantarum CRL1506

Abstract

Lacticaseibacillus rhamnosus CRL1505 and Lactiplantibacillus plantarum CRL1506 can increase resistance of mice to the infections induced by Gram negative pathogens. In this work, we aimed to advance in the characterization of the immunomodulatory properties of the CRL1505 and CRL1506 strains by evaluating their effect on the Toll-like receptor 4 (TLR4)-triggered immune response in macrophages. We performed experiments using the murine macrophage cell line RAW 264.7 stimulated with lipopolysaccharide (LPS) to evaluate the transcriptomic changes induced by lactobacilli. These in vitro experiments were complemented with in vivo studies in mice. The CRL1505 and CRL1506 strains were administered to animals, Peyer´s patches and peritoneal macrophages were isolated, and ex vivo stimulated with LPS. Microarray transcriptomic studies and qPCR confirmation showed that CRL1505- and CRL1506-treated RAW macrophages responded to LPS stimulation with higher il6, il15, ifnβ, ifnγ, csf3, and selp expression and lower il1β, il12, ccl2, ccl8, and icam1 expression compared to control macrophages. In addition, Peyer´s patches and peritoneal macrophages from mice treated with lactobacilli produced higher levels of TNF-α, IFN-γ, IL-6, and CSF3 and lower IL-1β, IL-12, CSF2, CCL2 and CCL8 after LPS stimulation. Of note, lactobacilli also modulate regulatory factors in macrophages. L. plantarum CRL1506 increased il10 and socs2 while L. rhamnosus CRL1505 upregulated il27, socs1 and socs3 in RAW cells. Both lactobacilli equally modulated socs1 and socs2 expressions and IL-10 and IL-27 production in Peyer´s patches macrophages and socs3 and IL-10 in peritoneal cells. The results show that L. rhamnosus CRL1505 and L. plantarum CRL1506 can modulate different inflammatory mediators, adhesion molecules and regulatory factors in macrophages after TLR4 activation. This effect would allow an improved protection against pathogens together with minimal inflammatory-mediated tissue damage as shown in our previous in vivo studies with Gram negative bacterial infections.