Psychological stress-induced microbial metabolite indole-3-acetate disrupts intestinal cell lineage commitment.

The brain and gut are intricately connected and respond to various stimuli. Stress-induced brain-gut communication is implicated in the pathogenesis and relapse of gut disorders. The mechanism that relays psychological stress to the intestinal epithelium, resulting in maladaptation, remains poorly understood. Here, we describe a stress-responsive brain-to-gut metabolic axis that impairs intestinal stem cell (ISC) lineage commitment. Psychological stress-triggered sympathetic output enriches gut commensal Lactobacillus murinus, increasing the production of indole-3-acetate (IAA), which contributes to a transferrable loss of intestinal secretory cells. Bacterial IAA disrupts ISC mitochondrial bioenergetics and thereby prevents secretory lineage commitment in a cell-intrinsic manner. Oral α-ketoglutarate supplementation bolsters ISC differentiation and confers resilience to stress-triggered intestinal epithelial injury. We confirm that fecal IAA is higher in patients with mental distress and is correlated with gut dysfunction. These findings uncover a microbe-mediated brain-gut pathway that could be therapeutically targeted for stress-driven gut-brain comorbidities.

A Gpr35-tuned gut microbe-brain metabolic axis regulates depressive-like behavior.

Gene-environment interactions shape behavior and susceptibility to depression. However, little is known about the signaling pathways integrating genetic and environmental inputs to impact neurobehavioral outcomes. We report that gut G-protein-coupled receptor, Gpr35, engages a microbe-to-brain metabolic pathway to modulate neuronal plasticity and depressive behavior in mice. Psychological stress decreases intestinal epithelial Gpr35, genetic deletion of which induces depressive-like behavior in a microbiome-dependent manner. Gpr35-/- mice and individuals with depression have increased Parabacteroides distasonis, and its colonization to wild-type mice induces depression. Gpr35-/- and Parabacteroides distasonis-colonized mice show reduced indole-3-carboxaldehyde (IAld) and increased indole-3-lactate (ILA), which are produced from opposing branches along the bacterial catabolic pathway of tryptophan. IAld and ILA counteractively modulate neuroplasticity in the nucleus accumbens, a brain region linked to depression. IAld supplementation produces anti-depressant effects in mice with stress or gut epithelial Gpr35 deficiency. Together, these findings elucidate a gut microbe-brain signaling mechanism that underlies susceptibility to depression.

Gpr35 shapes gut microbial ecology to modulate hepatic steatosis.

The gut microbiome is closely shaped by host genetic and dietary factors to regulate metabolic health and disease. However, the signaling mechanisms underlying such interactions have been largely unclear. Here we identify G protein-coupled receptor 35 (Gpr35) as a regulator of gut microbial ecology and the susceptibility to obesity and hepatic steatosis in mice. Both global and intestinal epithelia specific ablation of Gpr35 aggravated high-fat diet (HFD)-induced metabolic disturbance and hepatic steatosis in mice. Gpr35 deficiency induced a remarkable loss of goblet cells and an extensive remodeling of the gut microbiome, featuring enrichment of the Bacteroides and Ruminococcus genera. Antibiotics treatment and co-housing alleviated the metabolic disturbance markers in Gpr35 deficient mice. Spatiotemporal profiling and mono-colonization screening revealed that Ruminococcus gnavus synergized with HFD to promote hepatic steatosis possibly via tryptophan and phenylalanine pathway metabolites. Our results provide mechanistic insights into a genetic-diet-microbe interplay that dictates susceptibility to metabolic disorder.

Intrapleural chemo- and hyperthermotherapies for malignant pleural effusion: a randomized prospective study.

OBJECTIVE: The current prospective randomized study was designed to evaluate the safety and efficacy of combined intrapleural cisplatin and OK-432 (picibanil) plus hyperthermotherapy in patients with malignant pleural effusion (MPE). METHODS: A total of 358 patients with MPE due to end-stage malignancies were enrolled and randomly divided into two groups, A and B: the intrapleural combination of cisplatin and OK-432 with hyperthermotherapy (n = 179) or without hyperthermotherapy (n = 179), respectively. Mild toxicities such as nausea, vomiting or anorexia, bone marrow depression, and pyrexia were similar in both groups. RESULT: Patients in Group A (with hyperthermotherapy) showed a significantly higher overall response (93.4%) compared to those in Group B (79.8%, χ(2) = 43.11, p < .05). The median survival time for patients in Group A and Group B were 8.9 and 6.2 months, respectively (p > .05). After treatment, the quality of life scores were significantly increased in both groups as compared to prior treatment (p < .05). CONCLUSION: In conclusion, our study suggests that combined intrapleural cisplatin and OK-432 followed by hyperthermotherapy are more effective in the control of MPE and improve patients' quality of life.