Project description:We report that cellular ROS enzymatically generated in response to contact with lactobacilli in both mice and Drosophila has salutary effects against exogenous insults to the intestinal epithelium via the activation of Nrf2 responsive cytoprotective genes. RNA was isolated from the colons of untreated, PBS, E. coli, and LGG innoculated germ free mice and RNA-seq performed to identify the gene expression in response to each condition
Project description:We report that cellular ROS enzymatically generated in response to contact with lactobacilli in both mice and Drosophila has salutary effects against exogenous insults to the intestinal epithelium via the activation of Nrf2 responsive cytoprotective genes.
Project description:We report that cellular ROS enzymatically generated in response to contact with lactobacilli in both mice and Drosophila has salutary effects against exogenous insults to the intestinal epithelium via the activation of Nrf2 responsive cytoprotective genes.
Project description:An optimal gut microbiota influences many beneficial processes in the metazoan host. However, the molecular mechanisms that mediate and function in symbiont-induced host responses have not yet been fully characterized. Here, we report that cellular ROS enzymatically generated in response to contact with lactobacilli in both mice and Drosophila has salutary effects against exogenous insults to the intestinal epithelium via the activation of Nrf2 responsive cytoprotective genes. These data show that the xenobiotic-inducible Nrf2 pathway participates as a signaling conduit between the prokaryotic symbiont and the eukaryotic host. Indeed, our data imply that the capacity of lactobacilli to induce redox signaling in epithelial cells is a highly conserved hormetic adaptation to impel cellular conditioning to exogenous biotic stimuli. These data also highlight the role the microbiota plays in eukaryotic cytoprotective pathways and may have significant implications in the characterization of a eubiotic microbiota.
Project description:The intestinal ecosystem is balanced by dynamic interactions between resident and incoming microbes, the gastrointestinal barrier, and the mucosal immune system. However, in the context of inflammatory bowel diseases (IBD) where the integrity of the gastrointestinal barrier is compromised, resident microbes contribute to the development and perpetuation of inflammation and disease. In this context, probiotic bacteria exert beneficial effects enhancing epithelial barrier integrity. However, the mechanisms underlying these beneficial effects are only poorly understood. Here, we comparatively investigated the effects of four probiotic lactobacilli, namely L. acidophilus, L. fermentum, L. gasseri, and L. rhamnosus in a T84 cell epithelial barrier model. Results of DNA-microarray experiments indicating that lactobacilli modulate the regulation of genes encoding in particular adherence junction proteins such as E-cadherin and b-catenin were confirmed by qRT-PCR. Furthermore, we show that epithelial barrier function is modulated by Gram-positive probiotic lactobacilli via their effect on adherence junction protein expression and complex formation. In addition, incubation with lactobacilli differentially influences the phosphorylation of adherence junction proteins and of PKC isoforms such as PKCd which thereby positively modulates epithelial barrier function. Further insight into the underlying molecular mechanisms triggered by these probiotics might also foster the development of novel strategies for the treatment of gastrointestinal diseases (e.g. IBD).
Project description:Understanding how circulating metabolites enforce pathways in dysfunctional immune cells may illuminate modes of intervention directed at reviving immune function. The NRF2 pathway is the most widely documented cytoprotective axis in land-dwelling eukaryotes. However, the role of this pathway in CD8+ T cells—which seek and destroy tumors and pathogen infected cells—has yet to be elucidated. Our lab has conducted a RNAseq meta-analysis of CD8+ T cells upon tumor, viral and bacterial inoculation. Curiously, the NRF2 pathway was robustly upregulated in dysfunctional CD8+T cells. To further investigate the role of NRF2 in these contexts we developed a mouse model whereby the NRF2 axis is permanently hyperactivated in CD8+ T cells, hereafter referred to as NRF2Hi. Our in vivo data demonstrate that NRF2Hi CD8+ T cells offer little overall cytoprotection and poorly control tumors and pathogens versus wildtype (WT) control CD8+ T cells. To understand why upregulation of the NRF2 axis could be unfavorable to CD8+ T cell function we conducted RNAseq on NRF2Hi versus WT cells upon viral infection of mice. We found that NRF2Hi cells massively upregulate the prostacyclin receptor (PTGIR), which binds to prostacyclin—a circulating metabolite of arachidonic acid that has only been investigated in vasodilation and is seemingly benign to CD8+ T cells. To decipher the role of PTGIR in CD8+ T cells, we silenced its expression and observed a revival of CD8+ T cell function, significantly reducing tumor and pathogen burden. Collectively, our data illuminate a NRF2-regulated immune checkpoint, PTGIR. Interventions that suppress the interaction between PTGIR and prostacyclin may serve therapeutic benefit in clinical contexts such as cancer and chronic pathogen infections.