Intervene Role Of Green Tea Polyphenols To Ameliorate Gut Microbiota Alteration,and Intestinal Inflammatory Changes In High-fat Diet Induced Obese Dogs

High-fat diet altered gut microbiota and promotes obesity related inflammation,but Green tea polyphenols(GTPs)exhibit beneficial effects towards obesity and intestinal inflammation;however,the mechanism(s)of action and association with gut microbiota is unclear.Thus,the objectives of the present study were to examine the role of the gut microbiota the context of GTPs treatment for obesity and intestinal inflammation as well as its anti-inflammatory mechanism.After one month of acclimatization period,thirty male beagles,13-14 months old,and clinically healthy were randomly divided into five groups(n=6 per group).Dogs were fed either a normal diet or high-fat diet with low 0.48%,medium 0.96%,or high doses 1.92%of GTPs for 18 weeks.After 18 weeks of feeding blood samples were collected by depriving food the whole night.Serum was separated and the samples were stored at-800C for analysis of inflammatory cytokines.Four dogs were randomly sacrificed from each group with xylazine hydrochloride(1.5mg/kg,IM),and(20 mg/kg,IV)thiopental sodium injection according to body weight.Abdomen was opened and samples of the intestinal contents were collected and frozen immediately in formalin or liquid nitrogen.The samples were stored for further analysis.Effects on the gut microbiota were determining using high throughput sequencing.Intestinal and circulating inflammatory cytokine mRNA expression levels were determined by real-time polymerase chain reaction(qRT-PCR)or enzyme-linked immunosorbent assay(ELISA),respectively.The expression level of the Toll-like receptor 4(TLR4),Cyclooxygenase-2(COX-2)and Inducible nitric oxide synthase(iNOS)was determined by western blot.The inflammatory alterations to intestinal tissues were confirmed by hematoxylin and eosin(H&E)staining.The results are as follows:1.GTPs decreased the relative abundance of Bacteroidetes and Fusobacteria and increased the relative abundance of Firmicutes compared to high-fat diet group.The relative proportion of Acidaminococcus,Anaerobiospirillum,Anaerovibrio,Bacteroides,Blautia,Catenibactetium,Citrobacter,Clostridium,Collinsella,and Esherichia were significantly associated with GTP-induced weight loss.2.The mRNA expression of TNF-α,IL-6 and IL-1β were significantly(P<0.05)or(P<0.01)increased in the high-fat diet group compared to normal diet group,however,GTPs supplemented group’s show decreased mRNA expression(P<0.05)or(P<0.01)compared to the high-fat diet group.TNF-α concentration were significantly higher(P<0.05)in the high-fat diet group compared with the normal diet group.TNF-αconcentration was significantly lower(P<0.01)in the GTPs high dose group compared with the high-fat diet group.IL-6 concentration was significantly higher(P<0.01)in the high-fat diet group compared with the normal diet group.IL-6 concentration was significantly lower in the GTPs high dose group(P<0.05)compared with the high-fat diet group.There were no differences in IL-1β concentrations between high-fat diet group and normal diet group.However,IL-1(3 concentration significantly decreased(P<0.01)in GTPs high dose group compared with the high-fat diet group.3.GTPs also inhibited induction of the TLR4 signaling pathway.Oral supplementation of GTPs inhibit Cox-2 expression in intestinal tissue of dogs when compared with high-fat diet group which increased COX-2 expression significantly(P<0.05).Our result also shows that iNOS levels inhibit significantly(P<0.05)in GTPs high dose group after 18 weeks of treatment.4.The normal diet group had a normal architecture and mucosal morphology with an intact simple columnar epithelium.The wall of the small intestine(ileum)was markedly extended and lacteals dilated within the villi in high-fat diet group while,the dogs that were fed GTPs exhibited no inflammation or expanded lymphatics.Peyer patches are also clearly seen in the high GTPs dose group.In conclusion,the therapeutic effects of GTPs correspond with changes in gut microbiota and intestinal inflammation,which may related to the anti-inflammatory and anti-obesity mechanisms of GTPs.The results suggested that consumption of a high-fat diet alters gut microbiota structure while inducing obesity and inflammation.Meanwhile,GTPs supplementation exhibited significant protective effects against obesity and dysbiosis.