Nanovesicles From Lactobacillus johnsonii N6.2 Reduce Apoptosis in Human Beta Cells by Promoting AHR Translocation and IL10 Secretion

Abstract

L. johnsonii N6.2 releases nano-sized vesicles (NVs) with distinct protein and lipid contents. We hypothesized that these NVs play a central role in the delivery of bioactive molecules that may act as mechanistic effectors in immune modulation. In this report, we observed that addition of NVs to the human pancreatic cell line βlox5 reduced cytokine-induced apoptosis. Through RNAseq analyses, increased expression of CYP1A1, CYP1B1, AHRR, and TIPARP genes in the aryl hydrocarbon receptor (AHR) pathways were found to be significantly induced in presence of NVs. AHR nuclear translocation was confirmed by confocal microscopy. The role of NVs on beta cell function was further evaluated using primary human pancreatic islets. It was found that NVs significantly increased insulin secretion in presence of high glucose concentrations. These increases positively correlated with increased GLUT6 and SREBF1 mRNA and coincided with reduced oxidative stress markers. Furthermore, incubation of NVs with THP-1 macrophages promoted the M2 tolerogenic phenotype through STAT3 activation, expression of AHR-dependent genes and secretion of IL10. Altogether, our findings indicate that bacterial NVs have the potential to modulate glucose homeostasis in the host by directly affecting insulin secretion by islets and through the induction of a tolerogenic immune phenotype.

Microbial metabolites indole derivatives sensitize mice to D-GalN/LPS induced-acute liver failure via the Tlr2/NF-κB pathway

“…In addition, several important studies have indicated that indole derivatives are important endogenous AHR agonists (Rothhammer et al, 2016;Hezaveh et al, 2022). AHR signaling plays an important but controversial role in the inflammation response (Schuran et al, 2021;Teixeira et al, 2022). Thus, we also examined the role of AHR signaling with AHR agonist FICZ.…”

Internalization of extracellular vesicles from Lactobacillus johnsonii N6.2 elicit an RNA sensory response in human pancreatic cell lines

“…These results were validated by following the expression of host genes previously shown to be induced by L. johnsonii EV (Figure 3). As reported earlier, βlox5 cells treated with the EV activates the expression of genes encoding for intracellular RNA sensing proteins such as OAS, OAS, OASL, MX, IFI and IFIL (Teixeira et al, 2022). A time point experiment was performed to evaluate the kinetics of induction in expression of these genes in the presence of EV.…”

“…Next it was evaluated if the induction of the host RNA sensing genes may be triggered within the host endosome. While the endosome nucleic acid sensors TLR7 and TLR9 are not expressed in this cell line, the OAS1 variant p46 has been shown to colocalize with the endosomes in some cell lines (Teixeira et al, 2022;Wickenhagen et al, 2021). We evaluated whether the OAS1 p46 variant protein is expressed in βlox5 cells using Western blot analyses.…”

Type I Diabetes Pathoetiology and Pathophysiology: Roles of the Gut Microbiome, Pancreatic Cellular Interactions, and the ‘Bystander’ Activation of Memory CD8+ T Cells

“…Recent data causal models the beneficial effects of human umbilical cord mesenchymal stem cell vesicles containing exenatide as being mediated not only directly in pancreatic β-cells but also via alterations in the gut microbiome/permeability [ 68 ]. The beneficial effects of Lactobacillus johnsonii strain N.6 nanovesicles in T1DM are proposed to be mediated via the upregulation of AhR ligands and AhR activation, with effects in both pancreatic β-cells as well as in macrophages, which are induced into a M2b-like phenotype [ 69 ]. A number of preclinical studies over the past decade have shown the beneficial effects of Lactobacillus johnsonii in delaying T1DM onset, which is proposed to be mediated by a number of processes, including suppression of Th17 cells, increasing intestinal crypt Paneth cell numbers, and suppressing gastro-intestinal caspase-1 induction [ 70 , 71 , 72 ], whilst also decreasing the kynurenine/tryptophan ratio, increasing cytotoxic CD8 + T cells, and changing the patterned immune response, as shown in healthy human volunteers [ 73 ].…”