Expression Of TRPV1 And TRPV2 Receptors And Characteristics Of Microbiota In Gastric Mucosa Of Patients With Functional Dyspepsia

Objective:Functional dyspepsia(FD)is one of the most common diseases in gastroenterology department.The pathogenesis of FD is not completely clear,which may be related to visceral hypersensitivity and changes of digestive tract flora.TRPV1 and TRPV2 receptors are members of the Transient Receptor Potential(TRP)family,which play a role in nociceptive sensation and reflect visceral sensitivity to some extent.So in this study,we study the expression of TRPV1 and TRPV2 receptors in gastric mucosa and the changes of gastric mucosal microbiota in patients with FD and healthy people to explore the existence of visceral hypersensitivity and the characteristics of gastric mucosal microbiota in FD patients.Methods:We selected 30 patients with FD(FD_a)who met the diagnostic criteria of ROMEⅣand examined by gastroscopy in the affiliated Hospital of Qingdao University from July 2019 to October 2019,and selected fifteen healthy controls(HC_a)during the same period.The gastric antrum mucosa samples of all subjects were collected.The expression of TRPV1 and TRPV2 receptors in the gastric antrum mucosa were detected by immunohistochemical method in the two groups.In addition,we selected 15 patients with FD(FD_b)and 13 healthy controls(HC_b)from June2020 to July 2020.All the subjects in FD_band HC_bcompleted the Nepean Dyspepsia Index questionnaire and were examined by gastroscopy on the same day.The gastric antrum mucosa samples of all subjects were collected.High-throughput sequencing and bioinformatics analysis were used to analyze theα-diversity(Chao1 index,Shannon index),β-diversity,and the composition of its microbiota.Results:1.There was no statistically significant difference in age,sex,history of smoking and drinking between FD_aand HC_a,FD_band HC_b(P>0.05).2.The median expression score of TRPV1 in gastric antral mucosa in FD_awas 5.67(3.67,7.33),while in HC_awas 4.00(2.67,5.00).The expression of TRPV1in FD_awas higher than that in HC_a,and the difference was statistically significant(P<0.05).The median expression score of TRPV2 in gastric antral mucosa in FD_awas 4.00(3.67,6.67),while in HC_awas 5.67(3.67,8.00).The expression of TRPV2 in FD_awas slightly lower than that in HC_a,but the difference was not statistically significant(P>0.05).3.The Nepean Dyspepsia Symptom Index of the FD_bwas significantly higher than that of the HC_b(P<0.01).The overall quality of life score and the scores in the four areas of interference,control,diet and sleep in the HC_bwere significantly lower than those in the HC_b(P<0.05).4.In the determination of gastric mucosal microbiota,1291439 high quality sequences were obtained in the two groups,and 953 OTUs were obtained by classification operation.Among them,there were 195 OTUs specific to FD_b,78 OTUs specific to HC_b,and 680 OTUs in both groups.5.Analysis ofα-diversity of gastric mucosal microbiota:The Chao1index of FD_bwas 281.01(244.06,483.40),in HC_bit was 342.94(272.89,480.15),and there was no statistically significant difference(P>0.05).The Shannon index of FD_bwas 5.22(4.96,5.40),while in HC_bwas 5.03(5.01,5.20),and there was also no statistically significant difference(P>0.05).6.Analysis ofβ-diversity of gastric mucosal microbiota:We compared the changes of gastric mucosal microbiota community structure of the two groups based on Partial Least Squares Discrimination Analysis(PLS-DA).The results showed that there was a statistically significant difference in the community structure of gastric mucosal flora between FD_band HC_b(P<0.05).7.Species composition analysis:At the phylum level,the two groups were mainly composed of Proteobacteria,Firmicutes,Bacteroidetes,Fusobacteria,Actinobacteria,Deinococcus-Thermus.There was no statistically significant difference in the relative abundance of the above 6 dominant bacteria between the two groups(P>0.05).But the abundance of Cyanobacteria in FD_bwas significantly higher than it in HC_b(P<0.05).At the genus level,the two groups were composed of 10 dominant genera such as Streptococcus.There was no statistically significant difference in the relative abundance of these genera between the two groups(P>0.05).Through the comparison between the two groups,12 different generas such as Psychrobacter were found(P<0.05).8.LEf Se analysis:There was no statistically significant difference in the relative abundance of microbiota between the two groups at the phylum level(P>0.05).Different generas were found at the genus level.Among them,Ruminococcus＿torques＿group,Ruminococcus＿1,Hymenobacter,Hyphomicrobium,Ralstonia and Caulobacter were increased in FD_b,while the relative abundance of Parvimonas and Methylobacillus in HC_bwere significantly increased(P<0.05).9.Correlation analysis:In FD_b,the relative abundance of Ruminococcus＿torques＿group was moderately positively correlated with NDSI,the relative abundance of Ruminococcus＿1 was negatively correlated with interference,the relative abundance of Hymenobacter was negatively correlated with overall quality of life and interference,and the relative abundance of Hyphomicrobium was negatively correlated with overall quality of life,interference and diet.The relative abundance of Parvimonas was negatively correlated with NDSI,but positively correlated with overall quality of life,interference,control and diet.Conclusions:1.The expression of TRPV1 receptor in gastric antral mucosa of patients with FD was significantly increased,while the expression of TRPV2 had no significant change.2.Patients with FD had poorer quality of life,which was associated with increased relative abundance of species such as Ruminococcus＿torques＿group and decreased relative abundance of Parvimonas.3.The abundance and diversity of gastric mucosal microbiota in patients with FD had no significant change,but the structure of gastric mucosal microbiota changed significantly.The relative abundance of Cyanobacteria in patients with FD increased at the phylum level,while the relative abundance of Ruminococcus＿torques＿group increased and the relative abundance of Parvimonas decreased at the genus level.The content of opportunistic pathogens such as Streptococcus and Burkholderia-Paraburkholderia showed an increasing trend,while the content of probiotics such as Alloprevotella showed a downward trend.