The relationship between gut microbiota and depressive disorder has become a research focus in recent years. Within the microbiota-gut-brain axis, the gut microbiota influences the onset and progression of depressive disorder primarily through the tryptophan metabolic pathway. Tryptophan, an essential amino acid in humans, is subject to dual regulation by intestinal microorganisms, which modulate its metabolic balance via inflammatory stimulation and microbial metabolite production. In depression, excessive activation of the kynurenine branch of tryptophan metabolism leads to the accumulation of proinflammatory and neurotoxic metabolites, thereby exacerbating neuroinflammation in the brain. Intervention studies indicate that the antidepressant-like effects of probiotics and traditional Chinese medicine are associated with remodeling of the gut microbiota, restoration of tryptophan metabolic balance, and alleviation of neuroinflammation. Furthermore, targeted inhibition of kynurenine 3-monooxygenase can mitigate neuroinflammation by regulating microglial activity, thus improving depressive-like behaviors. In summary, the metabolite-inflammation axis represents a central node in the interaction regulation between tryptophan metabolism and the microbiota-gut-brain axis. This provides a theoretical foundation for developing novel therapeutic strategies targeting depression through modulation of gut microbiota-mediated tryptophan metabolism.
Tryptophan/metabolism* ; Gastrointestinal Microbiome/physiology* ; Humans ; Depressive Disorder/microbiology* ; Probiotics/therapeutic use* ; Brain/metabolism* ; Kynurenine/metabolism* ; Metabolic Networks and Pathways ; Animals ; Medicine, Chinese Traditional

Cancer metabolism as a field of research was founded almost 100 years ago by Otto Warburg, who described the propensity for cancers to convert glucose to lactate despite the presence of oxygen, which in yeast diminishes glycolytic metabolism known as the Pasteur effect. In the past 20 years, the resurgence of interest in cancer metabolism provided significant insights into processes involved in maintenance metabolism of non-proliferating cells and proliferative metabolism, which is regulated by proto-oncogenes and tumor suppressors in normal proliferating cells. In cancer cells, depending on the driving oncogenic event, metabolism is re-wired for nutrient import, redox homeostasis, protein quality control, and biosynthesis to support cell growth and division. In general, resting cells rely on oxidative metabolism, while proliferating cells rewire metabolism toward glycolysis, which favors many biosynthetic pathways for proliferation. Oncogenes such as MYC, BRAF, KRAS, and PI3K have been documented to rewire metabolism in favor of proliferation. These cell intrinsic mechanisms, however, are insufficient to drive tumorigenesis because immune surveillance continuously seeks to destroy neo-antigenic tumor cells. In this regard, evasion of cancer cells from immunity involves checkpoints that blunt cytotoxic T cells, which are also attenuated by the metabolic tumor microenvironment, which is rich in immuno-modulating metabolites such as lactate, 2-hydroxyglutarate, kynurenine, and the proton (low pH). As such, a full understanding of tumor metabolism requires an appreciation of the convergence of cancer cell intrinsic metabolism and that of the tumor microenvironment including stromal and immune cells.
Biosynthetic Pathways ; Carcinogenesis ; Glucose ; Glycolysis ; Homeostasis ; Kynurenine ; Lactic Acid ; Metabolism ; Oncogenes ; Oxidation-Reduction ; Oxygen ; Proto-Oncogenes ; Protons ; Quality Control ; T-Lymphocytes ; Tumor Microenvironment ; Yeasts

The present study was designed to investigate the effect Hypericum Perforatum (HP), on behavioral changes, corticosterone, TNF-alpha levels and tryptophan metabolism and disposition in bilateral ovariectomized rats compared to 17alpha -ethinylestradiol. Behavioral analysis by measuring immobility time in forced swimming test and open field test, serum and hippocampal corticosterone and TNF-alpha along with hippocampal kynurenine/tryptophan ratio were determined in mature ovariectomized rats treated orally either by HP at three different doses 125, 250, and 500 mg/kg/day or by 17alpha-ethinylestradiol 30 microg/kg/day for 30 days. Ovariectomized rats showed significant increase in immobility time in the forced swimming test. Along with elevation in serum and hippocampal TNF-alpha and corticosterone levels associated with significant increase in hippocampal kynurenine/tryptophan ratio. Immobility time in the forced swimming test was decreased in rats treated by different doses of HP in a dose dependent manner and 17alpha-ethinylestradiol with no concomitant changes in the open field test. Only Rats treated with HP exhibited significant decrease in the elevated serum and hippocampal TNF-alpha and corticosterone, which couldn't explain the associated insignificant effect on hippocampaus kynurenine/tryptophan ratio in comparison to ovariectomized untreated rats. It is concluded that increased tryptophan metabolism toward kynurenine secondary to elevated corticosterone and TNF-alpha might be one of the pathohphysiological mechanisms that could explain depression like state observed in this rat model. Further, the observed attenuating effect of HP on TNF-alpha and corticosterone could contribute in its antidepressant effect in this animal model by other ways than their effects on tryptophan-kynurenine metabolism pathway.
Animals ; Corticosterone* ; Depression ; Hippocampus* ; Hypericum* ; Kynurenine ; Metabolism ; Models, Animal ; Physical Exertion ; Rats* ; Tryptophan ; Tumor Necrosis Factor-alpha*

OBJECTIVETo explore the differences of metabolic footprint in the conditioned culture medium of placental explants between early-onset and late-onset severe preeclampsia.

METHODSIn 13 cases of early-onset severe preeclampsia and 14 cases of late-onset severe preeclampsia, the placentas were sampled at the surface of the maternal placenta. High performance liquid chromatography-mass spectrometry (HPLC-MS) was used to determine the differences in the metabolites in the conditioned culture medium of the placental villous explants cultured in 6% atmospheric O(2) for 96 h. Standard samples were used to establish the tryptophan and kynurenine chromatography library by HPLC-MS to analyze the concentration of tryptophan and kynurenine in the conditioned culture medium.

RESULTSThirty-six metabolites showed statistically significant differences between early-onset and late-onset severe preeclampsia (P<0.05). The concentration of kynurenine was significantly higher in early-onset severe preeclampsia than in late-onset severe preeclampsia (P<0.05).

CONCLUSIONEarly-onset and late-onset severe preeclampsia may have different pathogeneses. By detecting the concentration of metabolites, metabolomic strategies provide a new means for predicting the onset time of severe preeclampsia.

Chorionic Villi ; metabolism ; Culture Media, Conditioned ; chemistry ; Female ; Humans ; In Vitro Techniques ; Kynurenine ; metabolism ; Ornithine ; metabolism ; Placenta ; metabolism ; Pre-Eclampsia ; metabolism ; Pregnancy ; Tryptophan ; metabolism