The Altered Metabolism Of "microbiota-gut-brain Axis" In Naturally Occurring Depressive Macaca

Background:Major depressive disorder(MDD)is a debilitating brain-psychiatric illness that causes a heavy burden on society and families.To date the pathogenesis of depression is obscure,and there are no clinically objective diagnostic biomarkers.Gut microbes and their metabolites can participate in human central activities in multiple dimensions,thus "microbe-gutbrain" can be seen as a way to reveal the onset of depression and to develop objective biomarkers.Currently rodent depression models act as the main approach in depression research,but they cannot completely imitate the pathogenesis of humans.The non-human primate model is a more ideal depression model for its superior similarity in genetic information,social structures,and microbial functions.Objectives:1.Screen natural depressed monkeys and quantify their depressionlike phenotypes.2.Reveal the altered gut microbial structure and functions in depressive monkeys.3.Reveal the metabolic spectrum of the feces,peripheral and central system.4.Construct a "microbe-gut-brain" metabolic network.5.Reveal how the key metabolic modules drive the depressive phenotypes through the gut-brain metabolic network.Methods:1.According to the previously established object screening system and behavior evaluation system of natural occuring depressed(NOD)macaque,depressive and matched HC macaque were identified,and key depression-like phenotypes were quantified.2.Collect the feces of macaque,perform 16 s r RNA sequencing and metagenomic sequencing.Based on high-throughput data,perform microbial diversity analysis,metagenomic species analysis,and WGCNA analysis,etc.3.Perform metabolomics based on GC-MS and LC-MS on the feces,key peripheral tissues,and brain tissues of macaque.Construct the "microbiota-gut-brain metabolite spectrum",identify the differential metabolites.Perform WGCNA analysis,interaction network analysis,etc.4.Integrate the microbiome and metabolome results,map microbephenotype driving pathways,and analyze lipid subclasses in the brain.Results:1.We have screened 6 NOD macaque and found the corresponding HCs,the behaviors Huddle and Sitalone of the NOD macaque were significantly increased;while the Locomotion and Amicable behaviors were significantly decreased.2.Compared with HCs,there is no difference in alpha diversity in NOD macaque,but Beta diversity is significantly different.Differential OTUs are mainly enriched in Veillonellaceae,Laospirillaceae and Veillonococcus,belonging to Firmicutes(89.28%).The majority of differential OTUs are related to depression-like phenotypes;MGS analysis showed similar results.The enrichment of metagenomic function shows the disorder in microbial metabolism pathway,which is mainly related to the glutamatergic neuron activities.3.The metagenomic WGCNA obtained of co-expression gene modules,9 of which are highly correlated with 3 depression-like phenotypes.The main functions are enriched in lipid metabolism,amino acid metabolism,energy metabolism,PAMP,neurotransmitter metabolism,etc.4.In feces,colon,liver,serum,hippocampus,prefrontal cortex,and amygdala,a total of 6,218 metabolites were detected on the LC-MS platform;381 metabolites were detected on the GC-MS platform.Through multi-platform,we totally identified 559 differential metabolites,mainly lipids and amino acids.5.Metabolomic WGCNA obtained a total of 8 co-expression modules,4 of which are highly correlated with depression-like phenotypes.They are mainly enriched in glycerophospholipid and sphingolipid metabolism.We analyzed the behavioral microbial-driven genes from the metagenomics and constructed the microbial-driven sphingolipid metabolism pathway.6.The hippocampus is the main enrichment area of differential lipids.The abundance of glycerophospholipid subtypes is significantly downregulated.According to their metabolic relationships,we constructed the main disturbed lipid metabolism pathways in the hippocampus.Conclusions:1.Based on 16 s r RNA and metagenomics,we found that Firmicutes was the main altered microbiota between depressive and HC macaque.Glutamatergic synapse metabolism and lipid metabolism-related metabolism were the main different metagenomic functions,and are highly correlated with depression-like phenotypes.2.We drew the metabolite spectrum of the "microbe-gut-brain" axis,and found modules that were associated with depression-like phenotypes,which were mainly involved in fatty acyls and glycerophospholipids.The gut microbes may affect the synthesis of ceramide and caused the disordered sphingolipid MGB metabolism.