Clostridioides difficile infection promotes gastrointestinal dysfunction in human and mice post-acute phase of the disease.

OBJECTIVES: In the US, Clostridioides difficile (C. difficile) infection (CDI) is the 8th leading cause of hospital readmission and 7th for mortality among all gastrointestinal (GI) disorders. Here, we investigated GI dysfunction post-CDI in humans and mice post-acute infection. MATERIALS AND METHODS: From March 2020 to July 2021, we reviewed the clinical records of 67 patients referred to the UVA Complicated C. difficile clinic for fecal microbiota transplantation (FMT) eligibility. C57BL/6 mice were infected with C. difficile and clinical scores were determined daily. Stool samples from mice were collected to measure the shedding of C. difficile and myeloperoxidase (MPO) levels. On day 21 post-infection, Evans's blue and FITC-70kDa methods were performed to evaluate GI motility in mice. RESULTS: Of the 67 patients evaluated at the C. difficile clinic, 40 patients (59.7%) were confirmed to have CDI, and 22 patients (32.8%) with post-CDI IBS (diarrhea-type, constipation-type, and mixed-type). In infected mice, levels of MPO in stools and clinical score were higher on day 3. On day 21, mice recovered from body weight loss induced by CDI, and fecal MPO was undetectable. The total GI transit time (TGITT) and FITC-70kDa levels on the proximal colon were increased in infected mice (p = 0.002), suggesting a constipation phenotype post-acute phase of CDI. A positive correlation intestinal inflammation on day 3 and TGITT on day 21 was observed. CONCLUSION: In conclusion, post-infection intestinal dysfunction occurs in humans and mice post-CDI. Importantly, we have validated in the mouse model that CDI causes abnormal GI transit in the recovery phase of the disease, indicating the potential utility of the model in exploring the underlying mechanisms of post-infectious IBS in humans.

Myeloperoxidase as a biomarker for intestinal-brain axis dysfunction induced by malnutrition and Cryptosporidium infection in weanling mice

Abstract Cryptosporidiosis is a waterborne protozoal infection that may cause life-threatening diarrhea in undernourished children living in unsanitary environments. The aim of this study is to identify new biomarkers that may be related to gut-brain axis dysfunction in children suffering from the malnutrition/infection vicious cycle is necessary for better intervention strategies. Myeloperoxidase (MPO) is a well-known neutrophil-related tissue factor released during enteropathy that could drive gut-derived brain inflammation. We utilized a model of environmental enteropathy in C57BL/6 weanling mice challenged by Cryptosporidium and undernutrition. Mice were fed a 2%-Protein Diet (dPD) for eight days and orally infected with 107-C. parvum oocysts. C. parvum oocyst shedding was assessed from fecal and ileal-extracted genomic DNA by qRT-PCR. Ileal histopathology scores were assessed for intestinal inflammation. Prefrontal cortex samples were snap-frozen for MPO ELISA assay and NF-kb immunostaining. Blood samples were drawn by cardiac puncture after anesthesia and sera were obtained for serum amyloid A (SAA) and MPO analysis. Brain samples were also obtained for Iba-1 prefrontal cortex immunostaining. C. parvum-infected mice showed sustained stool oocyst shedding for six days post-infection and increased fecal MPO and inflammation scores. dPD and cryptosporidiosis led to impaired growth and weight gain. C. parvum-infected dPD mice showed increased serum MPO and serum amyloid A (SAA) levels, markers of systemic inflammation. dPD-infected mice showed greater MPO, NF-kB expression, and Iba-1 immunolabeling in the prefrontal cortex, an important brain region involved in executive function. Our findings suggest MPO as a potential biomarker for intestinal-brain axis dysfunction due to environmental enteropathy.