| Background:Depression in children and adolescents is one of the most common psychiatric disorders in this age group,with low diagnosis rate,poor treatment response and high suicide risk.The pathogenesis of depression in children and adolescents is unclear,which is also different from the depression in adults.It is a hot and difficult topic in this field to explore the specific pathogenesis of depression in children and adolescents.Recently,the disturbance of the gut microbiota may become the key pathogenesis of depression in children and adolescents.Most previous studies in this field have focused on fecal samples,while the gut mucosal and luminal microbiome may play a more important role in the pathogenesis of depression in children and adolescents.It is not feasible to collect mucosal and luminal samples throughout the intestinal tract in depressed patients in children and adolescents,and the rodent gut microbiota is significantly different from that of humans.Therefore,adolescent cynomolgus monkey depression model,which is closer to the human gut microbiota,was constructed to reveal the pathogenesis of the intestinal mucosal and luminal microbiota in depression in children and adolescents.Objective:Based on the adolescent cynomolgus monkey depression model that has the similar intestinal microbiota and neurobiological basis with depression in children and adolescents,we explore the microbial pathogenesis intestinal mucosal and luminal discriminative microbiome in depression in children and adolescents.Methods:1.The adolescent chronic unpredictable mild stress(CUMS)depression model in cynomolgus monkey was constructed.The depression-like behaviors of the cynomolgus monkeys were observed and tested,and the intestinal mucosal and luminal samples were also collected.2.The intestinal mucosal and luminal discriminative microbiome in the adolescent depression model was analysed by 16 S r RNA sequencing.3.The differential microbes in different locations between adolescent depressed cynomolgus monkeys and healthy controls(CON),and the co-occurrence network reflecting microbial changes was also constructed.4.PICRUSt microbial functional predictive analysis was used to explore the functional differences in intestinal mucosal and luminal microbial communities between the CUMS and the CON groups.5.The altered predicted microbial function in different intestinal locations was verified by targeted metabolomics technology.Results:1.The adolescent cynomolgus monkeys in CUMS group showed typical depression-like behaviors(higher huddle posture,lower locomotion,fewer attempts for the apple,and higher anxiety-like behaviors in human intruder test).2.In the adolescent cynomolgus monkeys,the Bacteroidetes dominated in both lumen and mucosa,while Firmicutes were more abundant in the lumen,and Campilobacterota and Spirochaetae were more abundant in mucosa at phylum level.The Prevotellaceae was dominated in both lumen and mucosa,while Lactobacillaceae and Lachnospiraceae were more abundant in lumen,and Helicobacteraceae and Brachyspiraceae were more abundant in mucosa at family level.3.There were 83 key discriminative ASVs in all eight sites(lumen and mucosa of cecum,ascending colon,transverse colon,and descending colon)between CUMS and CON groups.At the phylum,the majority of the discriminative ASVs were belonging to Firmicutes and Bacteriodetes.At the family level,the majority of the discriminative ASVs were belonging to Prevotellaceae and Lachnospiraceae.And also,Firmicutes and Bacteriodetes generated a characteristic covarying network.4.Using PICRUSt,we found a total of 27 significantly different microbiome community functions between CUMS and CON groups in mucosa.Only Citrate cycle(Tricarboxylic acid cycle)was observed to be enriched in lumen in CON animals.5.Compared with the adolescent cynomolgus monkeys in the CON group,the levels of D-glucose,fructose 1,6-bisphosphate,L-alanine,citric acid,tartaric acid,oxalic acid,glyceric acid,glyceric acid,hydroxypyruvic acid,and succinic acid were down-regulated in lumen in CUMS group.Conclusions:The intestinal mucosal and luminal microbiome was significantly changed in adolescent depressed cynomolgus monkeys,which were characterized by Firmicutes and Bacteriodetes at the phylum level,as well as Prevotellaceae and Lachnospiraceae at the family level,and the microbial functions disturbances were mainly concentrated in carbohydrate and energy metabolism pathways.Background:Depression in children and adolescents is the main cause of the disease burden in this age period,while most of the antidepressants,which are effective in depression adults,are less effective in depression in children and adolescents.Therefore,there is an urgent need to develop antidepressant targets based on the specific pathogenesis of depression in children and adolescents.The "Microbiota-gut-brain"(MGB)axis plays a key role in regulating human health and disease,and the association between depression and the MGB axis has also been widely verified,which may become a potential targets for depression.However,the human gut microbiota community and diversity changes with age,and the gut microbiota of children and adolescents is more susceptible to environmental factors than adults.However,there is currently a lack of studies related to the MGB axis of depression in children and adolescents.Objective:By integrating the function of the gut microbiota and the metaboliccharacteristics of the MGB axis in the depression model of adolescent cynomolgus monkeys,the typical metabolic pathways of the MGB axis in the depression model of adolescent cynomolgus monkeys were mapped to explore potential therapeutic targets for depression in children and adolescents.Methods:1.Based on constructing the adolescent CUMS cynomolgus monkey depression model,central samples(prefrontal cortex,amygdala and hippocampus)and peripheral samples(plasma,the mucosa and lumen of cecum,ascending colon,transverse colon and descending colon)were collected.2.Using shotgun metagenomic sequencing to detect the gut microbiota and functions in adolescent cynomolgus monkey depression model.3.The MGB axis metabolic characteristics and typical differential metabolic pathways were detected based on the LC-MS non-targeted metabolomics.4.The typical differential metabolic pathways of the MGB axis in the adolescent depression model of cynomolgus monkeys were integrated based on the Kyoto Encyclopedia of Genes and Genomes(KEGG)database.5.The schematic diagram of the disturbance of the MGB axis purine metabolism pathway was drawn by integrating metagenome and MGB axisnon-targeted metabolic data.6.The Spearman correlation was conducted between the metabolites in MGB axis purine metabolism pathway,differential microbiota and depression-like behaviors.Results:1.Based on the shotgun metagenomic sequencing,a total of 96 differentially abundant bacterial taxa were found between the CUMS and CON groups,including 52 differential bacterial taxa were enriched in the CUMS group and 44 were depleted in the CUMS group.At the phylum level,Fibrobacteres and Proteobacteria were depleted in CUMS group.The majority of differential bacterial taxa belonged to Firmicutes.2.A total of 497 differentially expressed metabolites were identified between CUMS and CON groups,whereas 71,30,149 and 304 differentially expressed metabolites were identified in brain tissues,plasma,gut and feces,respectively.The majority of the differentially expressed metabolites in MGB axis belonged to lipid and lipid-like molecules.However,only a limited number of differentially expressed metabolites were shared in these MGB axis samples.3.Based on the KEGG pathway analysis of the differential metabolites,we found a total of 69 perturbed metabolic pathways in the MGB axis,including 40 in the prefrontal cortex,8 in the hippocampus,4 in the amygdala,6 in plasma,14 in the gut,and 2 in feces.While,only purinemetabolism(ko00230)was widely altered in the MGB axis of prefrontal cortex,hippocampus,plasma,gut and feces.Various lipid metabolism pathways were also widely altered in MGB axis.4.Based on the shotgun metagenomic sequencing,a total of 1282 KEGG orthology genes(KO genes)were found to be significantly different in relative abundance between CUMS and CON groups.These differential KO genes are involved in 102 KEGG Modules.Among the KEGG Modules,two Modules in purine metabolism and three Modules in arginine and proline metabolism were significantly altered.In total,we found 17 differentially abundant metabolites and 19 differentially abundant KO genes involved in purine metabolism in MGB axis.5.The key differential bacteria species and metabolites in purine metabolism in the MGB axis formed strong and broad co-occurrence relationships with each other,especially in gut and feces The majority of differential bacteria species,especially genus Clostridium and Haemophilus,were significantly correlated with at least one metabolites of purine and lipid metabolism in the MGB axis.Conclusions:The gut microbiome disturbances in adolescent depression model of cynomolgus monkeys may lead to alterations in purine metabolism at a number of key locations in the MGB axis to contribute to the pathophysiology of depression during adolescence. |
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