Project description:Clostridioides difficile interactions with the gut mucosa are crucial for colonisation and establishment of infection, however key infection events during the establishment of disease are still poorly defined. To better understand the initial events that occur during C. difficile colonisation, we employed a dual RNA-sequencing approach to study the host and bacterial transcriptomic profiles during C. difficile infection in a dual-environment in vitro human gut model. Temporal changes in gene expression were analysed over 3-24h post infection and comparisons were made with uninfected controls.
Project description:Clostridioides difficile can cause severe infections in the gastrointestinal tract and affects almost half a million people in the U.S every year. Upon establishment of infection, a strong immune response is induced. We sought to investigate the dynamics of the mucosal host response during C. difficile infection.
Project description:Clostridioides difficile (C. difficile) is a common cause of antibiotic-induced diarrhea and causes the highest number of nosocomial infections. Only two antibiotics are currently recommended for treating C. difficile infection (CDI), which may contribute to unsatisfactory treatment outcomes and an increased likelihood of recurrence. In this study, we aim to evaluate the difference in gene expression between symptomatic and asymptomatic mice after infection with C. difficile using spatial transcriptomics analysis. We also aim to evaluate the spatial aspect of altered genes between different layers of intestinal mucosa (superficial vs deep) and identify the key pathways. Formalin-fixed paraffin-embedded (FFPE) intestinal sections were utilized for analysis using NanoStringTM platform to evaluate differential gene expressions in the caecum and colon. The IL-17 pathway, including Lcn2, Cxcl2, and S100a8 genes, was significantly upregulated in symptomatic mice. The IL-17 signaling pathway activated downstream signaling through NF-κB and MAPK pathways. Gene expression was significantly altered between the intestinal superficial and deep mucosal layers, highlighting layer-specific differences in gene expression patterns in the intestines of symptomatic and asymptomatic mice. Gene expression patterns in the enteric mucosa explained several clinical signs and lesions in CDI mice.
Project description:The obligate anaerobic, enteric pathogen Clostridioides difficile persists in the intestinal tract by forming antibiotic resistant endospores that contribute to relapsing and recurrent infections. Despite the importance of sporulation for C. difficile pathogenesis, environmental cues, and molecular mechanisms regulating sporulation initiation remain ill defined. Here, using RIL-seq to capture the Hfq-dependent RNA-RNA interactome, we discovered a network of small RNAs that bind to mRNAs encoding sporulation-related genes. We show that two of these small RNAs, SpoX and SpoY, regulate translation of the master regulator of sporulation, Spo0A, in an opposing manner, which ultimately leads to altered sporulation rates. Infection of antibiotic-treated mice with SpoX and SpoY deletion mutants revealed a global effect on gut colonization and intestinal sporulation. Our work uncovers an elaborate RNA-RNA interactome controlling the physiology and virulence of C. difficile and identifies a complex post-transcriptional layer in the regulation of spore formation in this important human pathogen.
Project description:The gut microbiome engenders colonization resistance against the diarrheal pathogen Clostridioides difficile but the molecular basis of this colonization resistance is incompletely understood. A prominent class of gut microbiome-produced metabolites important for colonization resistance against C. difficile is short chain fatty acids (SCFAs). In particular, one SCFA (butyrate) decreases the fitness of C. difficile in vitro and is correlated with C. difficile-inhospitable gut environments, both in mice and in humans. Here, we demonstrate that butyrate-dependent growth inhibition in C. difficile occurs under conditions where C. difficile also produces butyrate as a metabolic end product. Furthermore, we show that exogenous butyrate is internalized into C. difficile cells and is incorporated into intracellular CoA pools where it is metabolized in a reverse (energetically unfavorable) direction to crotonyl-CoA and (S)-3-hydroxybutyryl-CoA and/or 4-hydroxybutyryl-CoA. This internalization of butyrate and reverse metabolic flow of butyrogenic pathway(s) in C. difficile coincides with alterations in toxin release and sporulation. Together, this work highlights butyrate as a marker of a C. difficile inhospitable environment to which C. difficile responds by releasing its diarrheagenic toxins and producing environmentally-resistant spores necessary for transmission between hosts. These findings provide foundational data for understanding the molecular and genetic basis of how C. difficile growth is inhibited by butyrate and how butyrate alters C. difficile virulence in the face of a highly competitive and dynamic gut environment.