Project description:Autophagy, a cytoprotective mechanism in intestinal epithelial cells, plays a crucial role in maintaining intestinal homeostasis. Beyond its cell-autonomous effects, the significance of autophagy in these cells is increasingly acknowledged in the dynamic interplay between the microbiota and the immune response. In the context of colon cancer, intestinal epithelium disruption of autophagy has been identified as a critical factor influencing tumor development. This disruption modulates the composition of the gut microbiota, eliciting an anti-tumoral immune response. Here, we report that Atg7 deficiency in intestinal epithelial cells shapes the intestinal microbiota leading to an associated limitation of colitis induced by Citrobacter rodentium infection. Mice with an inducible, intestinal epithelial-cell-specific deletion of the autophagy gene, Atg7, exhibited enhanced clearance of C. rodentium, mitigated hyperplasia, and reduced pathogen-induced goblet cell loss. This protective effect is associated with the downregulation of pro-inflammatory pathways and an increase in Th17 and Treg responses—known protective immune responses against C. rodentium infection that are influenced by specific gut microbiota. Fecal microbiota transplantation and antibiotic treatment approaches revealed that the Atg7-deficiency-shapped microbiota, especially Gram-positive bacteria, plays a central role in driving resistance to C. rodentium infection. In summary, our findings highlight that inhibiting autophagy in intestinal epithelial cells contributes to maintaining homeostasis and preventing detrimental intestinal inflammation through microbiota-mediated colonization resistance against C. rodentium. This underscores the central role played by autophagy in shaping the microbiota in promoting immune-mediated resistance against enteropathogens
Project description:Opioids analgesics are frequently prescribed in the United States and worldwide. However, serious side effects such as addiction, immunosuppression and gastrointestinal symptoms limit their use. It has been recently demonstrated that morphine treatment results in significant disruption in gut barrier function leading to increased translocation of gut commensal bacteria. Further study indicated distinct alterations in the gut microbiome and metabolome following morphine treatment, contributing to the negative consequences associated with opioid use. However, it is unclear how opioids modulate gut homeostasis in the context of a hospital acquired bacterial infection. In the current study, a mouse model of C. rodentium infection was used to investigate the role of morphine in the modulation of gut homeostasis in the context of a hospital acquired bacterial infection. Citrobacter rodentium is a natural mouse pathogen that models intestinal infection by enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) and causes attaching and effacing lesions and colonic hyperplasia. Morphine treatment resulted in 1) the promotion of C. rodentium systemic dissemination, 2) increase in virulence factors expression with C. rodentium colonization in intestinal contents, 3) altered gut microbiome, 4) damaged integrity of gut epithelial barrier function, 5) inhibition of C. rodentium-induced increase in goblet cells, and 6) dysregulated IL-17A immune response. This is the first study to demonstrate that morphine promotes pathogen dissemination in the context of intestinal C. rodentium infection, indicating morphine modulates virulence factor-mediated adhesion of pathogenic bacteria and induces disruption of mucosal host defense during C. rodentium intestinal infection in mice. This study demonstrates and further validates a positive correlation between opioid drug use/abuse and increased risk of infections, suggesting over-prescription of opioids may increase the risk in the emergence of pathogenic strains and should be used cautiously. Therapeutics directed at maintaining gut homeostasis during opioid use may reduce the comorbidities associated with opioid use for pain management.
Project description:Microbiota composition regulates colitis severity, yet mechanisms employed by the innate immune system to regulate this remain unclear. We show that severity of colitis in Clec12a deficient animals is dependent on microbiota composition. Microbiota from a Clec12a-/- animal has expanded Faecalibaculum rodentium and transplantation of the Clec12a-/- microbiota or treatment with F. rodentium is sufficient to worsen colitis in wild-type mice. However, Clec12a-/- animals are resistant to colitis developmemt when rederived into an 11-member community, while addition of F. rodentium worsens disease. Colitis in Clec12a-/- mice is dependent on monocytes and cytokine and sequencing analysis in Clec12a-/- macrophages and serum shows enhanced inflammation with a reduction in phagocytic genes. We demonstrate that F. rodentium specifically binds to Clec12a and Clec12a-/- deficient macrophages are specifically impaired in their ability to phagocytose F. rodentium. Thus, Clec12a is an innate-immune surveillance mechanism to control the expansion of potentially harmful commensals while limiting inflammation
Project description:The intestinal epithelium is our first line of defense against infections of the gut and the plasticity in cellular differentiation of the intestinal epithelium is an important part of this response. Here we sequenced the colon intestinal epithelium from mice infected with Citrobacter rodentium to determine how the intestinal epithelium adapts in the context of an infection. By comparing these data to small intestinal organoids treated with cytokines (see related accessions) we determine that the intestinal epithelial response to C. rodentium infection correspond to a type III infection driven by IL22.
Project description:Host-pathogen interactions involve two critical strategies: resistance, whereby hosts clear invading microbes, and tolerance, whereby hosts carry high pathogen burden asymptomatically. Here, we investigate mechanisms by which Salmonella- superspreader hosts (SSP) maintain an asymptomatic state during chronic infection. We found that regulatory T cells (Tregs) are essential for this disease-tolerant state, limiting intestinal immunopathology and enabling SSP hosts to thrive, while facilitating Salmonella transmission. Treg depletion in SSP mice resulted in decreased survival, heightened gut inflammation and impairment of the intestinal barrier, without affecting Salmonella persistence. Colonic Tregs from SSP mice exhibited a unique transcriptomic profile characterized by the upregulation type-1 inflammatory genes, including the transcription factor T-bet. In the absence of Tregs, we observed robust expansion of cytotoxic CD4+ T cells, with CD4+ T cell depletion restoring homeostasis. These results uncover a critical host strategy to establish disease tolerance during chronic enteric infection, providing novel insights into mucosal responses to persistent pathogens and chronic intestinal inflammation.
Project description:Host-pathogen interactions involve two critical strategies: resistance, whereby hosts clear invading microbes, and tolerance, whereby hosts carry high pathogen burden asymptomatically. Here, we investigate mechanisms by which Salmonella- superspreader hosts (SSP) maintain an asymptomatic state during chronic infection. We found that regulatory T cells (Tregs) are essential for this disease-tolerant state, limiting intestinal immunopathology and enabling SSP hosts to thrive, while facilitating Salmonella transmission. Treg depletion in SSP mice resulted in decreased survival, heightened gut inflammation and impairment of the intestinal barrier, without affecting Salmonella persistence. Colonic Tregs from SSP mice exhibited a unique transcriptomic profile characterized by the upregulation type-1 inflammatory genes, including the transcription factor T-bet. In the absence of Tregs, we observed robust expansion of cytotoxic CD4+ T cells, with CD4+ T cell depletion restoring homeostasis. These results uncover a critical host strategy to establish disease tolerance during chronic enteric infection, providing novel insights into mucosal responses to persistent pathogens and chronic intestinal inflammation.
Project description:The mechanisms by which the mouse pathogen Citrobacter rodentium triggers effacement of the brush border microvilli, colitis, hyperplasia and dysbiosis remain poorly understood. We investigated the impact of C. rodentium infection on the proteomic and metabolic landscapes of intestinal epithelial cells (IECs) in vivo using isobaric labeling proteomics and targeted metabolomics. We found that infection depletes proteins involved in butyrate uptake, glycolysis, TCA cycle, lipid metabolism and oxidative phosphorylation with aparallel, increased production of creatine/phosphocreatine and cholesterol. The evolving ecological niche within the infected gut was concomitant with a reduction in butyrate-producing commensal bacteria and expansion of Proteobacteria that can metabolize cholesterol. These changes coincide with the modulation of IEC transcription factors by C. rodentium, specifically phosphorylation of Kdm5a, demethylation of histone H3 (Lys-4) and cleavage of Srebp2. Taken together our results show that whilst engaging with the host in a race to control innate immune responses, C. rodentium and the changing microbiota shape the metabolism flow in IECs.
Project description:We report that dietary iron protects mice from infection by Citrobacter rodentium. Iron induces a state of insulin resistance and increases glucose availability in the gut, thereby attenutating C. rodentium virulence. Additionally the pathogen appears to be driven towards a long-term commensal state. Here, we identify mutations in persistent and avirulent Citrobacter rodentium isolates from mice given an iron supplemented diet.
Project description:Many enteric pathogens employ a type III secretion system (T3SS) to translocate effector proteins directly into the host cell cytoplasm, where they subvert signaling pathways of the intestinal epithelium. Here, we report that the anti-apoptotic regulator HS1-associated protein X1 (HAX-1) is an interaction partner of the T3SS effectors EspO of enterohaemorrhagic Escherichia coli (EHEC) and Citrobacter rodentium, OspE of Shigella flexneri and Osp1STYM of Salmonella enterica serovar Typhimurium. EspO, OspE and Osp1STYM have previously been reported to interact with the focal adhesions protein integrin linked kinase (ILK). We found that EspO localizes both to the focal adhesions (ILK localization) and mitochondria (HAX-1 localization), and that increased expression of HAX-1 leads to enhanced mitochondrial localization of EspO. Ectopic expression of EspO, OspE and Osp1STYM protects cells from apoptosis induced by staurosporine and tunicamycin. Depleting cells of HAX-1 indicates that the anti-apoptotic activity of EspO is HAX-1 dependent. Both HAX-1 and ILK were further confirmed as EspO1 interacting proteins during infection using T3SS-delivered EspO1. Using cell detachment as a proxy for cell death we confirmed that T3SS-delivered EspO1 could inhibit cell death induced during EPEC infection, to a similar extent as the anti-apoptotic effector NleH, or treatment with the pan caspase inhibitor z-VAD. In contrast, in cells lacking HAX-1, EspO1 was no longer able to protect against cell detachment, while NleH1 and z-VAD maintained their protective activity. Therefore during both infection and ectopic expression EspO protects cells from cell death by interacting with HAX-1. These results suggest that despite the differences between EHEC, C. rodentium, Shigella and S. Typhimurium infections, hijacking HAX-1 anti-apoptotic signaling is a common strategy to maintain the viability of infected cells.