| 1.BackgroundDuring the perioperative period,Intestinal Ischemia/Reperfusion(I/R)injury manifests as a prevalent pathophysiological event.Recent studies have highlighted microbial metabolites as potential therapeutic agents for mitigating intestinal injuries.Specifically,Indole-3-lactic acid(ILA),an endogenous tryptophan metabolite derived from L.murinus,has been identified as a potent ligand for the Aryl hydrocarbon Receptor(AhR).Emerging evidence suggests that ILA modulates cellular inflammation and apoptosis through its interaction with AhR,yet its definitive role in the context of intestinal I/R injury remains to be elucidated.Intriguingly,AhR has been documented to activate the Yes-associated Protein(YAP)signaling cascade,a critical pathway that orchestrates cell proliferation,differentiation,and apoptosis.Another pivotal player in the intestinal I/R injury landscape is Nuclear Factor erythroid 2-related Factor 2(Nrf2),known for its anti-inflammatory and anti-oxidative properties.However,the potential involvement of YAP and Nrf2 in mediating the protective effects of tryptophan metabolites during intestinal I/R injury is yet to be clearly defined.In light of this,our study meticulously assesses the association between the concentrations of three specific L.murinus-derived tryptophan metabolites(namely,indole-3-lactate,indole-3-acetic acid,and indole-3-acetaldehyde)in the intestinal milieu and the degree of intestinal I/R injury.Furthermore,we delve into deciphering whether ILA’s protective mechanism against intestinal I/R injury is contingent upon the modulation of YAP and Nrf2 pathways.2.Research ObjectivesTo clarify whether microbial-derived tryptophan metabolites have a protective effect on intestinal I/R injury and whether this protection is mediated through YAP and Nrf2.3.Research Methods3.1 Participant researchTryptophan metabolites in the feces of patients undergoing cardiopulmonary bypass surgery were analyzed using liquid chromatography/mass spectrometry.Serum biochemical markers and the Lausanne Intestinal Failure Score were used to assess intestinal function post-surgery.3.2 In vivo Animal ExperimentsThe impact of Indole-3-lactic acid(ILA)on intestinal ischemia/reperfusion(I/R)injury was assessed in a mouse model,including the content of tryptophan metabolites in the cecal contents,histopathological scoring,and levels of MDA and GSH.The effects and mechanisms of ILA on WT and Nrf2-deficient mice post-intestinal I/R were explored using immunofluorescence,quantitative RT-PCR,Western blot,and ELISA methods.3.3 Ex vivo Organoid ExperimentsAn intestinal organoid hypoxia/reoxygenation(H/R)injury model was established to simulate intestinal I/R injury.The effects and mechanisms of ILA on intestinal organoids under H/R were investigated using the same methods as in 3.2.4.Research Results4.1 Postoperative Recovery in Patients:Patients with higher preoperative fecal ILA concentrations exhibited better intestinal function postoperatively.4.2 Findings in Animal and Organoid Models:ILA reduced intestinal epithelial cell damage in the mouse intestinal I/R model and promoted the proliferation of intestinal stem cells.It also attenuated cellular oxidative stress and upregulated the expression of YAP and Nrf2.4.3 Role of YAP and Nrf2:The YAP inhibitor verteporfin reversed the protective effects of ILA.In mice deficient in Nrf2,ILA failed to alleviate oxidative stress damage,highlighting the importance of Nrf2 in the protective mechanism mediated by ILA.5.Research ConclusionsThe content of ILA in patients’ preoperative feces is negatively correlated with intestinal functional damage during CPB surgery.The ILA content decreases in the cecal contents of mice after I/R injury.ILA can alleviate intestinal I/R injury by positively regulating YAP and Nrf2. |
PDF Full Text Request