The Nlrp12 inflammasome negatively regulates NOD2-mediated adjuvanticity, endotoxic shock and host defence afforded by an immunomodulatory muropeptide.
ABSTRACT: Transcriptional profiling of intestinal response to Citrobacter rodentium in wild-type and Nlrp12-deficient mice Four-conditions experiment, Nlrp12-deficient mouse infected by Citrobacter rodentium at day 7 versus non-infected Nlrp12-deficient mice with two biologicals replicates , Wild-type mouse infected by Citrobacter rodentium at day 7 versus non-infected Wild-type mice with two biologicals replicates and Nlrp12-deficient mouse infected by Citrobacter rodentium versus Control mouse infected by Citrobacter rodentium at 2 differents times ( day 0 and post infection at day 7 ) with three biologicals replicates
Project description:Retinoic-acid receptor-related orphan receptor-γt-positive (RORγt+) innate lymphoid cells (ILCs) produce interleukin (IL)-22 and IL-17, which are critical for protective immunity against enteric pathogens. The molecular mechanism underlying the development and survival of RORγt+ ILCs is not thoroughly understood. Here we show that Dedicator of cytokinesis 8 (DOCK8), a scaffolding protein involved in cytoskeletal rearrangement and cell migration, is essential for the protective immunity against Citrobacter rodentium. A comparative RNA sequencing-based analysis reveals an impaired induction of antimicrobial peptides in the colon of DOCK8-deficient mice, which correlates with high susceptibility to infection and a very low number of IL-22-producing RORγt+ ILCs in their GI tract. Furthermore, DOCK8-deficient RORγt+ ILCs are less responsive to IL-7 mediated signaling, more prone to apoptosis and produce less IL-22 due to a defect in IL-23-mediated STAT3 phosphorylation. Our studies reveal an unsuspected role of DOCK8 for the function, generation and survival of RORγt+ ILCs. Control and DOCK8 KO mice were infected with 2X109 CFU of Citrobacter rodentium and day 8 post infection mice were sacrificed and their colons were harvested (n=5) . Total RNA was purified from the infected colons with RNeasy mini kit (Qiagen). RNA sequencing was performed (pooled RNA sample from five mice in each group) at Genomic Core Facility Southwestern Medical Center, University of Texas.
Project description:To further understand immune mechanims involved in regulating intestinal inflammation, we employed whole genome microarray expression profiling as a discovery platform to identify genes with the potential of regulating inflammation in the absence of IL-10. Whole colon tissue from IL-10-deficient and C57BL/6 (wild-type) mice was collected 2 weeks after Citrobacter rodentium infection and from uninfected controls. Consistent with the histological and cellular analysis, expression levels of many chemokines and cytokines involved in recruiting leukocytes and promoting inflammation were, on average, lower in IL-10 deficient compared to wild-type mice after infection. An exception to this general trend was IL-27, a cytokine with both pro- and anti-inflammatory properties. Two weeks after Citrobacter rodentium challenge, total RNA was extracted and analyzed from whole colon tissue of infected IL-10-deficient and wild-type mice, and compared to uninfected controls. Each sample contained equal amounts of total RNA from 4-5 female mice which were pooled and used in the experiment.
Project description:Defense against attaching and effacing (A/E) bacteria requires the sequential generation of IL-23 and IL-22 to induce protective mucosal responses. While the critical source of IL-22 has been identified as CD4+ and Nkp46+ innate lymphoid cells (ILCs), the precise source of IL-23 is unclear. Here, we use genetic techniques to deplete specific classical dendritic cell (cDC) subsets and analyze immunity to the A/E pathogen Citrobacter rodentium. We find that Zbtb46+ cDCs, and specifically Notch2-dependent intestinal CD11b+ cDCs, but not Batf3-dependent CD103+ cDCs, are required for IL-23 production and immunity against C. rodentium. Notch2 controls cDC differentiation at a terminal step mediated by lymphotoxin signaling. Importantly, these results provide the first demonstration of a non-redundant function of CD11b+ cDCs in vivo. Analysis of genes differentially expressed between WT, Batf3 KO and Notch2 KO colons following C. rodentium infection. Mice were infected with 2 x 10^9 C. rodentium and colons harvested at either Day 4 or Day 9.
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:An experiment to test the equivalence of the Citrobacter rodentium RegA and E.Coli SMS 3-5 homologue 8 Conditions (4 Genotypes by 2 treatments) in duplicate. Reference design without dye swaps.
Project description:Identification of the targets of RegA with and without bicarbonate stimulation by comparing RegA knockout to multicopy RegA transgenics. RegA is an AraC like transcription factor identified in a mutational screen for virulence genes in Citrobacter rodentium, an attaching and effacing pathogen that causes transmissible colonic hyperplasia in mice. This experiment compares the RegA null strain with a multicopy plasmid rescue of this null strain in the presence and absence of bicarbonate with the aim of identifying pathogenesis related genes related to the early and late stages of attachment and effacement. Keywords: genetic modification, transcription factor, induction A strain of Citrobacter rodentium with a knockout of RegA was compared to the same strain rescued with a multicopy plasmid containing the wildtype RegA gene. These strains were analyzed with and without bicarbonate in an unconnected two factor design with dye balanced biological replicates.
Project description:The identification of Atg16L1 as a susceptibility gene has implicated antibacterial autophagy in the pathogenesis of Crohn's disease, a major type of inflammatory bowel disease (IBD). However, the role of Atg16L1 during extracellular bacterial infections of the intestine has not been sufficiently examined and compared to the function of other IBD susceptibility genes such as Nod2. We now find that Atg16L1 mutant mice are extraordinarily resistant to intestinal disease induced by the model bacterial pathogen Citrobacter rodentium. We further demonstrate that Atg16L1 deficiency alters the intestinal environment to mediate an enhanced immune response that is dependent on monocytic cells, and that Atg16L1/Nod2 double mutant mice lose this advantage. These results reveal an unappreciated immuno-suppressive function of an IBD gene, and raise the possibility that gene variants that affect the autophagy pathway were evolutionarily maintained to protect against certain life-threatening infections. Twenty samples have been analyzed. All are colonic tissue from mice. Controls are uninfected WT mice, uninfected Atg16L1 mutant mice (Atg16L1HM) (n=3/genotype). Treatment conditions are tissue from WT and Atg16L1 mutant mice 6 days after C. rodentium infection (n=4/genotype) and 15 days after infection (n=3/genotype).
Project description:It is crucial to decipher the host-microbiota interactions as they are involved in intestinal homeostasis and diseases. Caspase Recruitment Domain 9 (Card9) is an inflammatory bowel disease (IBD) susceptibility gene coding for an adapter protein for innate immunity toward many microorganisms. Card9-/- mice are more susceptible to colitis induced by Citrobacter rodentium as a result of impaired of the IL-22 pathway. C. rodentium is a natural mouse pathogen widely used to model human infections with Enteropathogenic Escherichia coli and Enterohaemorrhagic E. coli. To explore the role of the gut microbiota in the susceptibility of Card9-/- mice to C. rodentium infection, we colonized WT germ-free (GF) mice with the microbiota of WT (WT-->GF) or Card9-/- (Card9-/- -->GF) mice and challenged them with C. rodentium. Card9-/- -->GF mice were more susceptible than WT-->GF mice to C. rodentium. To examine the mechanisms responsible for this defect, we compared the cecum transcriptomes of WT -->GF and Card9-/- -->GF mice before and during C. rodentium-induced colitis. The number of down-regulated and up-regulated genes on day 12 after C. rodentium infection was lower in Card9-/- -->GF mice than WT-->GF mice. Card9-/- -->GF mice showed a significant down-regulation of gut morphogenesis and wound healing pathways suggesting that recovery is impaired in Card9-/- -->GF mice after C. rodentium infection. Immune response and cell division pathways were up-regulated in WT-->GF mice but not in Card9-/- -->GF confirming the defect of global response to infection when only the Card9-/- microbiota was transferred. The most induced and differentially expressed genes between Card9-/- -->GF and WT-->GF mice on day 4 after C. rodentium infection were Reg3g (encoding REGIIIγ) and Reg3b (encoding REGIIIβ). Overall design: Germ-free (GF) C57BL/6 wild-type (WT) mice were inoculated by oral gavage with fresh stools from conventional WT (WT-->GF) or Card9-/- (Card9-/- -->GF) mice. Three weeks after the colonization, WT-->GF and Card9-/- -->GF mice were infected by oral gavage with 1x10^9 CFU of C. rodentium strain DBS100. 5 mice of each groups (WT-->GF and Card9-/- -->GF) were sacrified before infection. 6 mice of each group were sacrified 4 days after infection, 5 mice of each group were sacrified at day 12 and 3 WT-->GF mice and 5 Card9-/- -->GF mice were sacrified at day 22.