Lactobacillus rhamnosus GR-1 enhances NF-kappaB activation in Escherichia coli-stimulated urinary bladder cells through TLR4

Abstract

BackgroundEpithelial cells of the urinary tract recognize pathogenic bacteria through pattern recognition receptors on their surface, such as toll-like receptors (TLRs), and mount an immune response through the activation of the NF-kappaB pathway. Some uropathogenic bacteria can subvert these cellular responses, creating problems with how the host eliminates pathogens. Lactobacillus is a genus of lactic acid bacteria that are part of the microbiota and consist of many probiotic strains, some specifically for urogenital infections. Immunomodulation has emerged as an important mode of action of probiotic and commensal lactobacilli and given the importance of epithelial cells, we evaluated the effect of the urogenital probiotic Lactobacillus rhamnosus GR-1 on epithelial immune activation.ResultsImmune activation through the NF-kappaB pathway was initiated by stimulation of T24 urothelial cells with heat-killed Escherichia coli and this was further potentiated when cells were co-cultured with live L. rhamnosus GR-1. Heat-killed lactobacilli were poor activators of NF-kappaB. Concomitant stimulation of bladder cells with E. coli and L. rhamnosus GR-1 increased the levels of the pro-inflammatory cytokine TNF, whereas IL-6 and CXCL8 levels were reduced. Another probiotic, L. rhamnosus GG, was also able to potentiate NF-kappaB in these cells although at a significantly reduced level compared to the GR-1 strain. The transcript numbers and protein levels of the lipopolysaccharide receptor TLR4 were significantly increased after co-stimulation with E. coli and lactobacilli compared to controls. Furthermore, inhibition of TLR4 activation by polymixin B completely blocked the lactobacilli potentiation of NF-kappaB.ConclusionsThe immunological outcome of E. coli challenge of bladder cells was influenced by probiotic L. rhamnosus GR-1, by enhancing the activation of NF-kappaB and TNF release. Thus the urogenital probiotic L. rhamnosus GR-1 modulated the activation of the NF-kappaB through increased levels of TLR4 on the bladder cells and altered subsequent release of cytokines from urothelial cells. By influencing immunological factors such as TLR4, important in the process of fighting pathogens, lactobacilli could facilitate pathogen recognition and infection clearance.

Deep Sequencing-Based Transcriptome Analysis of Chicken Spleen in Response to Avian Pathogenic Escherichia coli (APEC) Infection

“…In this study, TLR4 was significantly up-regulated in MD (2.3 folds) and SV (2.9 folds) compared to NC, which was consensus to the study of TLR4 in human. After co-stimulation the T24 human bladder carcinoma cell with E. coli and lactobacilli, TLR4 were significantly increased in both mRNA and protein level, and inhibition of TLR4 blocked the lactobacilli potentiation of NF-kappaB [30]. TLR2 were also up regulated in MD (3.0 folds) and SV (3.3 folds) compared to NC.…”

Preventive effect ofLactobacillus reuteriCRL1324 on Group BStreptococcusvaginal colonization in an experimental mouse model

“…Up to date, there is strong evidence related to the role of probiotics, mainly LAB, in the maintenance of the health or in the prevention of disease by modulation of the host's immune response (Karlsson et al . ). Several studies have demonstrated that lactobacilli exert an anti‐inflammatory effect in a vaginal infection models (Joo et al .…”

“…Up to date, there is strong evidence related to the role of probiotics, mainly LAB, in the maintenance of the health or in the prevention of disease by modulation of the host's immune response (Karlsson et al 2012). Sev-eral studies have demonstrated that lactobacilli exert an anti-inflammatory effect in a vaginal infection models (Joo et al 2011(Joo et al , 2012Wagner and Johnson 2012;Rizzo et al 2013), and can activate the immune system, improving the host's response against urogenital pathogens (Lazarenko et al 2012;Wagner and Johnson 2012).…”

Vaginal microbiota and its role in HIV transmission and infection

“…Therefore, vaginal lactobacilli might be involved in controlling HIV infections by suppressing NF-jB effects (Wagner & Johnson, 2012). On the other hand, the vaginal strain L. rhamnosus GR-1 was also shown to stimulate TLR4 at both mRNA and protein level in cells challenged with E. coli, with concomitant increased NF-jB activation and TNF release (Karlsson et al, 2012). The role of these findings in relation to HIV expression remains to be studied.…”