Enteric glial cells aggravate the intestinal epithelial barrier damage by secreting S100ß under high-altitude conditions.

Damage to the intestinal epithelial barrier (IEB) has been reported under high-altitude (HA) conditions and may be responsible for HA-associated gastrointestinal (GI) disorders. However, this pathogenetic mechanism does not fully explain the GI stress symptoms, such as flatulence and motility diarrhea, which accompany the IEB damage under HA conditions, especially for the people exposed to HA acutely. In the present study, we collected the blood samples from the people who lived at HA and found the concentration of enteric glial cells (EGCs)-associated biomarkers increased significantly. HA mouse model was then established and the results revealed that EGCs were involved in IEB damage. Zona occludens (ZO)-1, occludin, and claudin-1 expression was negatively correlated with that of glial fibrillary acidic protein (GFAP) and S100ß under HA conditions. In order to learn more about how EGCs influence IEB, the in vitro EGC and MODE-K hypoxia experiments that used hypoxic stimulation for simulating in vivo exposure to HA was performed. We found that hypoxia increased S100ß secretion in EGCs. And MODE-K cells cultured in medium conditioned by hypoxic EGCs showed low ZO-1, occludin, and claudin-1 levels of expression. Furthermore, treatment of MODE-K cells with recombinant mouse S100ß resulted in diminished levels of ZO-1, occludin, and claudin-1 expression. Thus, HA exposure induces greater S100ß secretion by EGCs, which aggravates the damage to the IEB. This study has revealed a novel mechanism of IEB damage under HA conditions, and suggest that EGCs may constitute a fresh avenue for the avoidance of GI disorders at HA.

Enteric fungi protect against intestinal ischemia-reperfusion injury via inhibiting the SAA1-GSDMD pathway.

INTRODUCTION: Prophylactic antifungal therapy has been widely used for critical patients, but it has failed to improve patient prognosis and has become a hot topic. This may be related to disruption of fungal homeostasis, but the mechanism of fungi action is not clear. As a common pathway in critical patients, intestinal ischemia-reperfusion (IIR) injury is fatal and regulated by gut microbiota. However, the exact role of enteric fungi in IIR injury remains unclear. OBJECTIVES: This is a clinical study that aims to provide new perspectives in clarifying the underlying mechanism of IIR injury and propose potential strategies that could be relevant for the prevention and treatment of IIR injury in the near future. METHODS: ITS sequencing was performed to detect the changes in fungi before and after IIR injury. The composition of enteric fungi was altered by pretreatment with single-fungal strains, fluconazole and mannan, respectively. Intestinal morphology and function impairment were evaluated in the IIR injury mouse model. Intestinal epithelial MODE-K cells and macrophage RAW264.7 cells were cultured for in vitro tests. RESULTS: Fecal fungi diversity revealed the obvious alteration in IIR patients and mice, accompanied by intestinal epithelial barrier dysfunction. Fungal colonization and mannan supplementation could reverse intestinal morphology and function impairment that were exacerbated by fluconazole via inhibiting the expression of SAA1 from macrophages and decreasing pyroptosis of intestinal epithelial cells. Clodronate liposomes were used to deplete the number of macrophages, and it was demonstrated that the protective effect of mannan was dependent on macrophage involvement. CONCLUSION: This finding firstly validates that enteric fungi play a crucial role in IIR injury. Preventive antifungal treatment should consider damaging fungal balance. This study provides a novel clue to clarify the role of enteric fungi in maintaining intestinal homeostasis.

A mesoporous polydopamine-derived nanomedicine for targeted and synergistic treatment of inflammatory bowel disease by pH-Responsive drug release and ROS scavenging.

Repurposing clinically approved drugs to construct novel nanomedicines is currently a very attractive therapeutic approach. Selective enrichment of anti-inflammatory drugs and reactive oxygen species (ROS) scavenging at the region of inflammation by stimuli-responsive oral nanomedicine is an effective strategy for the treatment of inflammatory bowel disease (IBD). This study reports a novel nanomedicine, which is based on the excellent drug loading and free radical scavenging ability of mesoporous polydopamine nanoparticles (MPDA NPs). By initiating polyacrylic acid（PAA）polymerization on its surface, a "core-shell" structure nano-carrier with pH response is constructed. Then, under alkaline conditions, using the π-π stacking and hydrophobic interaction between the anti-inflammatory drug sulfasalazine (SAP) and MPDA, the nanomedicines (PAA@MPDA-SAP NPs) loaded efficiently (928 µ g mg-1) of SAP was successfully formed. Our results reveal that PAA@MPDA-SAP NPs can pass through the upper digestive tract smoothly and finally accumulate in the inflamed colon. Through the synergistic effect of anti-inflammation and antioxidation, it can effectively reduce the expression of pro-inflammatory factors and enhance the intestinal mucosal barrier, and finally significantly alleviate the symptoms of colitis in mice. Furthermore, we confirmed that PAA@MPDA-SAP NPs have good biocompatibility and anti-inflammatory repair ability under inflammation induction through human colonic organoids. In summary, this work provides a theoretical basis for the development of nanomedicines for IBD therapy.