Research On Bifidobacterium Breve CCFM1025 With The Antidepressant-like Effect

Depression is a common mood disorder characterized by a persistent low mood.World Health Organization's statistics indicate that over 320 million people worldwide currently suffer from depression.By 2030,depression will be the leading contributor to the global burden of disease.Depression is a heterogeneous disorder with an inconsistent response to treatment.The hypothesis of depression pathogenesis primarily involves the hypothalamic-pituitary-adrenal(HPA)axis hyperfunction and the lack of monoamine.In recent years,the crucial role of the “microbiota-gut-brain axis” has been proved in the development of depression,which provides insight for developing novel antidepressants.Psychobiotics are a class of probiotics that regulate central nervous function and provide a superior approach when compared with classic antidepressants for their delayed onset of action,low efficiency,and side effects.This study aimed to screen novel psychobiotics with antidepressant-like potential,using both in vitro and in vivo methods.Genomics and metabolomics were also used to investigate its antidepressive mechanism.The clinical effect was further verified in major depressed patients.The main findings were listed as follows:(1)A putative enterochromaffin cell model(RIN14B)was used to screen the bacteria with anti-depressive potential in vitro.Thirty lactic acid bacterium were tested for their effect on stimulating tryptophan hydroxylase gene(Tph1)expression,5-hydroxytryptophan(5-HTP),and serotonin(5-HT)secretion in the RIN14 B cells.All strains were then tested in the chronic unpredictable mild stress-induced mice,for their effects on behaviors,HPA axis responses,and neurotransmitter levels.Correlations between the in vitro and animal results were modeled by partial least squares(PLS)analysis.The RIN14 B cell-based in vitro screening,especially the detection of bacteriastimulated Tph1 m RNA has good predictive validity for strains' in vivo anti-depressive capacity.The top four candidates were selected by the principal component analysis.Bifidobacterium breve isogenic strain,FHLJDQ3M5 and CCFM1025,showed an opposite anti-depressive effect,thus were selected for the follow-up studies.(2)A five-week CCFM1025 intervention significantly reduced the depression and anxiety-like behaviors of chronically stressed mice.HPA axis hyperactivity and concomitant inflammation were also alleviated,as reflected by the normalization of Nr3c1 gene expression,reduced serum corticosterone,and reduced hippocampal IL-6,T-bet,and Ror-?t m RNA levels;Besides,CCFM1025 could down-regulate the hippocampal p CREB-c-FOS expression and up-regulate the prefrontal cortex m BDNF expression;Moreover,CCFM1025 ameliorated the stress-induced gut microbial dysbiosis,through increasing ?-diversity and the abundance of short-chain fatty acidproducing bacteria(Coprococcus,Oscillospira).The altered gut microbiome also increased intestinal TPH1 expression and 5-HTP secretion,which positively correlated with the serum 5-HTP,brain 5-HT,and the reduction of depression-like behaviors.(3)In contrast to CCFM1025,FHLJDQ3M5 showed no significant antidepressantlike effect in chronically stressed mice.FHLJDQ3M5 was used as a negative control for the comparative genomic and metabolomic analysis of CCFM1025.The results showed a potentially broader carbohydrate utilization capacity in CCFM1025 because of the higher gene contents that encode glycoside hydrolases.In the bacterial fermentation products,higher levels of neuromodulatory metabolites including hypoxanthine,tryptophan,and nicotinate were observed in CCFM1025.The in vivo genomic and metabolomics analysis further proved that CCFM1025 differentially shaped the gut microbial composition,resulted in higher cecal xanthine,tryptophan,and short-chain fatty acids levels than FHLJDQ3M5-treated mice.CCFM1025 enhanced the fatty acid and tryptophan biosynthesis,identified by in silico analyses(gut-brain module analysis and metabolite enrichment analysis).(4)In the randomized,placebo-controlled clinical trial,the four-week CCFM1025 treatment significantly reduced the rating score(including MADS and HAMDS)of major depressed patients.The Brief Psychiatric Rating Score(BPRS)indicated that CCFM1025 had a specific effect on mood regulation.CCFM1025 also significantly alleviated the intestinal dysfunction but showed no significant effect on abdominal pain and indigestion.Besides,gut microbial diversity was changed by CCFM1025,the relative abundance of Ruminococcus(torques group),Lachnospiraceae UCG-003,and Ruminococcaceae UCG-009 was higher than that in placebo controls.However,the intestinal short-chain fatty acid levels were not significantly changed by CCFM1025.