The Role And Mechanism Of Glo1 And CD36 Via Mediating Inflammatory Pathway In Depression

BACKGROUNDDepression is a mental illness with a very high prevalence,a lack of pleasure,low mood,and a high suicide rate.At present,the pathogenesis of depression mainly involves the neurotransmitter theory,changes in the HPA axis,activated oxidative stress,neurotrophic loss,and chronic inflammation.Increasing evidence shows that oxidative stress,free radicals and inflammatory responses are highly related to the development of depression.Studies have shown that oxidative stress can cause inflammation,and inflammation can also lead to oxidative stress.When ROS is excessive in oxidative stress,it will activate the NLRP3inflammasome to promote the immune response,and eventually cause cellular damage.Based on the important role of oxidative stress and inflammasome in depression,the inflammatory pathway has been recognized to regulate the progress of depression,but its key molecules and its regulatory mechanism need to be further explored.Glo1 is the main detoxifying enzyme system of carboxyaldehyde.In glyoxalase system,Glo1 plays a leading role and provides an effective enzyme protection mechanism.It consumes MG content and increases GSH level to prevent the production of carbonyl aldehyde-mediated glycosylation,oxidative stress,and inflammatory response.As a B-type scavenger receptor,CD36 plays an important role in lipid metabolism and inflammatory response,and lipid metabolism and inflammatory response can play an important role in the occurrence and development of depression through gut microbiota.Previous studies have shown that Glo1 and CD36is highly related to inflammasome,however,it is unclear whether Glo1 and CD36 can regulate the occurrence and outcome of depression by participating in the inflammatory pathway.OBJECTIVE1.Explore the relationship of Glo1 and depression and whether Glo1plays a role in depression by mediating inflammatory pathway.3.Explore the role of CD36 in depression and whether if it modulates the inflammatory pathway and gut microbiota.METHODS1.The expression of Glo1 was detected by RT-qPCR and Western Blot technology in PBMC,CUMS rats and CSDS mice.2.We constructed Glo1 interfering AAV,and performed localized injection of mouse hippocampal DG brain area to observe the effect of Glo1 interference on behaviour.We observed depression-related behavioral phenotypes of CD1which naturally highly express glo1 mice.3.We observed the behavioral phenotypes of mice by conducting CSDS model after localized injection of Glo1 overexpressing AAV in hippocampal DG brain area.4.We constructed the astrocyte Glo1 siRNA interference model and astrocyte Glo1-siRNA interference superimposed LPS stimulation model,and used LDH detection,RT-qPCR and Western Blot technology to detect the inflammasome response.5.The inflammasome response was detected in hippocampal levels after Glo1 overexpression of adenovirus-associated virus.6.The expression of CD36 was verified in patients with depression and depressed mice models.7.We detected the NLRP3 inflammasome response in the hippocampus of CD36^-/-mice.We detected the microbial changes in cecum contents of CD36^-/-mice by 16s RNA technology.RESULTS1.Glo1 was significantly reduced in the hippocampus of depression patients PBMC,CUMS rat and CSDS mice.2.After the interference of Glo1 expression in the hippocampal DG region of the mice,the immobility time of the mice in the interference group increased significantly;the number of entrance and distance in central area decreased significantly in the interference group in the open field test.We detected high expression of Glo1 mRNA levels in the CD1mouse hippocampus compared to C57 mice,and significantly reduced immobility time in the tail suspension test and forced swimming test.3.The mice showed CSDS stress resilient behavior after Glo1overexpression:Glo1-CSDS mice showed significantly higher SI ratios in the interaction zone than EGFP-CSDS mice;Glo1-CSDS mice also showed significantly higher sucrose preference than EGFP-CSDS mice.4.LDH is up-regulated in the culture medium and the expression of inflammasome factors such as NLRP3 and IL-1?is significantly increased after si-Glo1 interference;The expression of ASC,NLRP3,p-NF-?B,pro-IL-1?and pro-Caspase-1 was significantly increased in the astrocyte of si-Glo1 interferes with LPS stimulation model.5.Glo1 overexpression in mouse hippocampus can significantly reduce the expression of ASC and increase the expression of pro-Caspase-1;The mature Caspase-1 of Glo1-CSDS group mice is significantly down-regulated,accompanied by a significant up-regulation of pro-IL-1?;NF-?B were significantly down-regulated in overexpressed Glo1-CSDS mice,but there was no significant difference in nuclear NF-?B;Glo1-CSDS mice expressed significantly increased p-TrKB.6.CD36 was significantly upregulated in PBMC of depressed patients and in the hippocampus of CSDS mice.7.The mRNA and protein expressions of NLRP3 and ASC in the hippocampus of CD36^-/-mice were significantly reduced,and the levels of NF-?B,IL-1?and Caspase-1 in CD36^-/-mice were down-regulated compared with WT mice.Microbial richness indice?Chao?was decreased and diversity indice?Simpson?was increased in CD36^-/-mice compared with WT mice.The abundance of Ruminococcaceae,Erysipelotrichaceae,Bacteroidaceae,Mycoplasmataceae,Rikenellaceae and Christensenellaceae at the family level were altered significantly.Moreover,at the genus level,the CD36^-/-mice exhibited the enrichment of Bacteroides,Alloprevotella,Rikenella and Ruminococcaceae_UCG-013,and the reduction of Tyzzerella₃,Allobaculum,Roseburia and Christensenellaceae_R-7_group in comparison with the WT group.CONCLUSION1.Significantly down-regulated Glo1 in depressed patients and animal models,the depressive behavior exhibited by Glo1 interference in hippocampus of mice,and the depression-resilient behavior phenotype of CD1 mice,suggested that Glo1 expression is related to depression,and the reduction of Glo1 may be involved in the pathogenesis of depression;Overexpression of Glo1 makes mice exhibit a stress-insensitive phenotype to CSDS,suggesting Glo1's potential protective effect on depression.2.The expression of inflammasome and related inflammatory factors in the Glo1 interference model of astrocytes was significantly up-regulated,suggesting that Glo1 interference will cause cytotoxic reactions and inflammasome reactions.In the model of astrocyte Glo1 interference with LPS stimulation,inflammasome,inflammatory factors and related signaling pathway molecular are further aggravated,suggesting that the reduction of Glo1 can affect the inflammasome pathway response,which may be a potential mechanism for Glo1 to participate in the pathogenesis of depression.3.The improvement of inflammatory response and related signaling molecules in the hippocampus after overexpression of Glo1 with CSDS in mice suggested that Glo1 might play a potential protective role in mice by improving the inflammatory response.4.CD36 was significantly up-regulated in depressed patients and animal models,suggesting the correlation between CD36 and depression,and the up-regulation of CD36 may be involved in depression.5.The improvement of NLRP3 inflammasome response in the hippocampus of CD36^-/-mice and the changes in the microbiota of the cecum contents suggest that CD36 may play a role in depression by regulating the NLRP3 inflammasome pathway and gut microbiota.