An Akkermansia Muciniphila Subtype Improves High-fat Diet Induced Metabolic Disorder And Neurodegenerative Processes In Mice

The prevalence of obesity and diabetes has caught more and more attention,and it makes a threat to public health.Particularly,obesity and diabetes increase the incidence of many kinds of mental illness,including depression,dementia,stroke and memory decay.Obesity and diabetes are characterized by increased systemic inflammation,the elevated inflammation also happened in central nervous system(CNS).Inflammation is one of the most important underly mechanism of the corrrelation between obesity and mental illness.Akkermansia muciniphila was firstly isolated from human fecal in 2004.Since its isolation,Akkermansia muciniphila caught much attention.It was found that Akkermansia muciniphila closely co-related with obesity and diabetes.Its abundance dramatically decreased in obese and type 2 diabetes patients.Akkermansia muciniphila treatment can reverse high-fat diet induced metabolic disorders,including fat-mass gain,metobolic endotoxemia,adiposity and insulin resistance.It was found that different strains within a species initiated different immunologic reaction in host,they may not react in similar way to the host.In fact,they may exert inverse effect on the host.We isolated a strain of Akkermansia muciniphila from fecal and confirmed it is a different subtype with the type strain.1.Objectives:Giving high-fat diet(HFD)induced obese and type 2 diabetes mice Akkermansia muciniphila subtype daily to explore1.1 whether Akkermansia muciniphila subtype can slow down weight gain and improve blood glucose control and the underlying mechanism.1.2 whether Akkermansia muciniphila subtype can alleviate mental disorders induced by HFD and the mechanism of Akkermansia muciniphila subtype interact with the host.2.Methods2.1 animals and grouping40 female C57BL/6(8-week-old)mice were randomly divided into four groups,including high-fat diet plus PBS gavage(HFD-PBS,n=10),high-fat diet plus Akkermansia muciniphila subtype gavage(HFD-AKK,n=10),normal chow diet plus PBS gavage(NCD-PBS,n=10),normal chow diet plus Akkermansia muciniphila subtype gavage(NCD-AKK,n=10).HFD-AKK and NCD-AKK were orally given Akkermansia muciniphila subtype daily with a dose of 2×108CFU/0.2ml,and the HFD-PBS and NCD-PBS groups were given the vehicle PBS.Weight gain and food consumption were measured weekly.2.2 in the middle and the end of experiment,fasting blood glucose were measured and oral glucose tolerance test was conducted.2.3 Akkermansia muciniphila quantification by real-time PCR before and after treatment2.4 At the end of the experiment,sucrose preference test(SPT)was conducted to test the despression level of mice.After this,mice were subjected to Y-maze test to test their short term memory.2.5 fecal samples were collected for 16S metagenomic sequencing.2.6 short chain fatty acids(SCFA)produced by Akkermansia muciniphila subtype and type strain were analysed intro.2.7 inflammation and brain function related factors in serum were analysed2.8 histological examination2.9 Statistical analyse3.Results:3.1 Akkermansia muciniphila subtype administration can decrease food consumption in both HFD groups and NCD groups.Mice in HFD-PBS had a significant higher body weight than those in the other three groups.And mice in NCD-PBS also had a slight higher body weight than those in NCD-AKK.3.2 Before the experiment Akkermansia muciniphila was randomly colonized in the gut of mice,without obvious differences between groups.After Akkermansia muciniphila subtype gavage,the amount of Akkermansia muciniphila in Akkermansia muciniphila subtype supplemented groups(HFD-AKK and NCD-AKK)were significantly higher than those in PBS supplemented groups(HFD-PBS and NCD-PBS)(P<0.05).3.3 Akkermansia muciniphila subtype can significantly decrease fasting blood glucose and improve glucose control in mice fed with HFD.3.4 Mice in HFD groups(HFD-PBS and HFD-AKK)consumed significantly less sucrose water than the NCD groups(NCD-PBS and NCD-AKK)(P<0.001),which could not be restored by Akkermansia muciniphila subtype treatment;Akkermansia muciniphila subtype treatment can improve special memory of mice fed high fat diet.3.5 IL-10 in mice of NCD-AKK significantly higher than the other three groups.Followed by HFD-AKK,slightly higher than those in HFD-PBS and NCD-PBS.Results showed that tryptophan in HFD-PBS was statistically higher than the other three groups(P<0.05),without obvious difference among the other groups(P>0.05).In HFD-PBS and HFD-AKK,the concentration of serotonin was significantly decreased compared to NCD-PBS and NCD-AKK.3.6 Diet dramatically changed gut microbiota community structure,with obviously decrease in beta diversity and Bifidobacterium,and obvious increase in Bacteroides and Bilophila;Akkermansia muciniphila subtype affected gut microbiota to a less extent.Akkermansia muciniphila subtype significantly increased bifidobacterium and significantly decreased Bilophila,and it was negatively correlated with Bacteroides.3.7 Akkermansia muciniphila subtype dramatically increased goblet cells in intestinal of HFD mice,and Akkermansia muciniphila subtype alleviated liver steatosis caused by HFD.3.8 compared with type strain,Akkermansia muciniphila subtype produced higher concentration of acetic acid,propionic acid and isovaleric acid.4.Conclusion:(1)Akkermansia muciniphila subtype exerted beneficial effect on body weight and blood glucose control,(2)Akkermansia muciniphila subtype alleviated the memory decay caused by high-fat diet.(3)These functions may related to the decrease of Bilophila and Bacteroides,increase of Bifidobacterium,SCFA production and decrease of systemic inflammation.