Effects Of N-3 PUFA On Gut Microbiota And Fatty Acid Levels In Patients With Hashimoto’s Thyroiditis

Objective:The research objectives of this master’s project are as follows:1.To explore the differences between the patients with Hashimoto’s thyroiditis(HT)and healthy people in the levels of phospholipid fatty acids in erythrocyte membranes and intestinal microflora through case control.2.Based on the results of the case-control study,we conducted a randomized controlled trial to investigate the effect of deep-sea fish oil(FO)rich in n-3 polyunsaturated fatty acids(PUFA)on thyroid function in Hashimoto’s thyroiditis patients.Methods:1.Research object recruitment and grouping:Case-control study:59 Hashimoto’s thyroiditis patients(HT group,n=59)and 22 healthy volunteers(HC group,n=22)aged 25 to 65 were recruited.Peripheral venous blood and fecal samples were collected from all volunteers,and basic information and medication status were collected through questionnaire survey.Randomized controlled study:Patients with Hashimoto’s thyroiditis who met inclusion criteria were recruited and randomly assigned to the following two groups:fish oil group(FO group,n=20)and corn oil group(CO group,n=19).The fish oil group was given deep-sea fish oil(containing 84%n-3 PUFA,DHA:EPA=2:1)2.6g/day,and the corn oil group was given corn oil 2.6g/day for 8 weeks.Fasting peripheral venous blood and fecal samples were collected from all volunteers at baseline,4 and 8 weeks after intervention.2.Parameter analysis:Using automatic electrochemical luminescence instrument to detect the serum Thyroid peroxidase antibody(TPOAb)resistance,anti thyroglobulin antibody(TGAb),Thyroid stimulating hormone(Thyroid stimulating hormone,TSH),three free iodine armour gland original glycine(3,5,3’-triiodothyronine,FT3)and Free thyroxine(FT4);Automatic biochemical analyzer was used to detect routine indexes of blood.Alanine aminotransferase(ALT),Aspartate aminotransferase(Aspartate aminotransferase),alanine Aminotransferase(Alt),Aspartate Aminotransferase,AST),y-glutamyl transpeptidase(GGT),Creatinine(Cr),Urea(Urea),urea(Urea),Urea(Urea),uric acid(Urea)and Creactive protein(CRP)levels;The phospholipid fatty acid composition of erythrocyte membrane was determined by gas chromatography.Fecal samples were sequenced by 16S rRNA to analyze the composition of the gut microbiome.Results:1.Case-control study:(1)The levels of TPOAb,TGAb and TSH in HT group were significantly higher than those in HC group,while those of LB,ALB/GLOB,AST/ALT,UREA,UREA/Cr and COR were significantly lower than those in HC group.Serum FT3 and FT4 were not significantly different between the two groups.The contents of EPA,DHA and total n-3 fatty acid of erythrocyte membrane in HT group were significantly lower than those in HC group,and the contents of Saturated fatty acid(SFA)were significantly higher than those in HC group.(2)The HT group of intestinal flora diversity was significantly lower than the HC group,diversity exists significant difference between the two groups(R=0.540,P=0.001).At the phylum level,the relative abundance of Acidobacteria and Proteobacteria in HT group was significantly higher than that in HC group(P<0.05),the relative abundance of Verrucomicrobia in HC group was significantly higher than that in HT group(P<0.05).At the genus level,the relative abundance of Dialister in HC group was significantly higher than that in HT group(P<0.05).At the phylum level,Acidobacteria was significantly positively correlated with TPOAb,TGAb and FT3,while Actinobacteria was significantly negatively correlated with FT4.Bifidobacterium had a significant negative correlation with FT4 at the genus level.2.Randomized controlled studies:(1)After 8 weeks of intervention,TGAb level in FO group decreased significantly with the increase of intervention time(P=0.002).There was significant difference in TSH level between FO group and CO group(P=0.05).Intervention could significantly increase in FO group,fish oil DHA levels(P<0.05),intervention and time effect were significantly affected the DHA levels.There was an interaction between intervention and time effect on total SFA and total MUFA levels.In FO group,total SFA level decreased significantly while total MUFA level increased significantly.The total n-3 fatty acid level decreased with the increase of intervention time,and the total n-3 fatty acid content increased significantly in FO group.The n-3 index increased with time,and the n-3 index of FO group increased significantly.(2)ACE index of FO group was significantly higher than that of CO group.After intervention,the ACE index of CO group was significantly lower than that before intervention(P<0.05).The β-diversity exists significant difference between groups with CO(R=0.461,P=0.001).At the door level,the relative abundance of Actinobacteria,Epsilonbacteraeota and Rokubacteria increased significantly after the intervention of FO group.The relative abundance of Actinobacteria and Epsilonbacteraeota in FO group was significantly higher than that in CO group.At the genus level,the relative abundance of Bradyrhizobium,Curvibacter,Hydrogenophaga,Lysinibacillus and RB41 in FO group were significantly higher after intervention than before.The relative abundance of Curvibacter,Hydrogenophaga and RB41 in FO group was significantly higher than that in CO group.At the gate level,Acidobacteria and TSH showed a significant negative correlation,while Tenericutes and TGAb showed a significant positive correlation.Bifidobacterium has a significant negative correlation with FT3 at the genus level.Conclusion:1.The content of total n-3 fatty acids in erythrocyte membrane phospholipids of Hashimoto’s thyroiditis patients was lower than that of healthy people,including DHA and EPA;Compared with healthy people,Hashimoto’s thyroiditis patients have lower richness and diversity of gut microbiota,higher abundance of Bacillus,lower abundance of beneficial bacteria such as Bifidobacterium,and different composition of gut microbiota.2.Deep-sea fish oil supplementation could increase the content of n-3 fatty acids,significantly increase the DHA level,reduce the abundance of Bacillus,and regulate the intestinal microbiota in patients with Hashimoto’s thyroiditis.Serum TGAb levels decreased with time,while TPOAb levels did not change significantly.