The Effect Of Zinc Deficiency On Ulcerative Colitis And Its Epigenetics Mechanism

Objective:The etiology of ulcerative colitis(UC)is not clear,and its pathogenesis is the interaction of genetic susceptibility,environmental factors,immune response and infection.Recent studies have found that gene methylation is the cause of certain immune diseases and inflammatory reactions;meanwhile,daily intake as an external environmental factor may regulate the methylation process by altering the methyl donor content or altering key enzyme activities.Besides,zinc is mainly absorbed from diet,the experiment has confirmed that zinc deficiency can reduce the methylation of Cp G islands in the IL-6 promoter region of inflammatory cells,and thus promote the inflammatory response;while the zinc binding domain of DNA methyltransferases(DNMTs)controls the activation of enzyme.Therefore,we hypothesize that zinc deficiency may reduce the methylation of Cp G islands in the promoter region of IL-6 by decreasing the enzyme activity of DNMTs,after which increased expression of IL-6 causes a strong inflammatory response,resulting in the development of UC.Method: 1.Collection of colon tissue and serum samples: 24 patients with UC aged 18-65 years were selected as the experimental group and 30 normal persons were the control group.Under the colonoscope,the margin of the colon of the colon seen in the experimental group and the normal tissue of the control group were taken.A part of the fresh tissue was immediately subjected to the enzyme activity test,and the remaining part was subjected to DNA methylation examination.Peripheral blood serum under fasting conditions was used for the detection of zinc and IL-6.2.Questionnaire survey: A semi-quantitative questionnaire survey was performed on all patients in the experimental group.The results were compared with the daily-recommended intake of zinc in the "Chinese Dietary Nutrients Reference Intake Scale",and the patient's personal information was also collected.Dietary habits are used for analysis.3.Detecting serum zinc levels in peripheral veins: Serum zinc was measured using a zinc ion detection kit by zinc-gonochrome method.4.DNA methylation of Cp G islands in the promoter region of IL-6 gene: Genomic DNA was extracted from human colon tissue samples and the degree of methylation was detected by MSP method.5.Detection of serum IL-6 expression: detected by enzyme-linked immune sorbent assay(ELISA).6.DNMTs Enzyme Activity Assay: The DNMTs enzyme activity was measured using a colorimetric kit.Result: 1.Zinc of diet in the experimental group: Zinc of diet in UC patients was lower than recommended dietary intake(women 7.0386 mg/d vs.7.5 mg/d;male 7.78 mg/d vs.12.5 mg/d);Among18 patients with low zinc intake,41.7% were underweight(BMI=15.52,n=10).2.Serum zinc level in human: There was no significant difference in serum zinc level between the experimental group and control group(15.40±2.01?mol/L vs.15.48±1.86?mol/L,P=0.88>0.05).3.Methylation level of Cp G islands in the promoter region of IL-6 gene: Cp G islands in the promoter regions of IL-6 gene were divided into two parts for analysis.Among-1069,-1061,-1057,and-1001 loci named MSP-1,there were no significantly different between the experimental group and the control group(P = 0.37> 0.05);and for the MSP-2 group of-628,-610,-574,and-491 loci,there was significantly different from that of the control group(P=0.015<0.05).The overall methylation level of the control group was significantly different(P=0.022<0.05);comparing unmethylated U+/methylation M+ of Cp G islands from two different primers and the total IL-6 region,the U+/M+ ratio was higher in the experimental group than in the control group,indicating an increased demethylation.4.Detection of serum IL-6 expression: The serum IL-6 concentration in the experimental group was significantly higher than that in the control group(1075.02 ± 661.95 vs.583.43 ± 425.10 pg/ml,P = 0.002 <0.05).5.Detection of DNMTs enzyme activity in human colon mucosa: The DNMTs enzyme activity of UC patients was significantly lower than that of the control group(P>0.05).Conclusion: 1.Serum zinc level in UC patients were not affected by reduced dietary intake.2.Increased serum IL-6 expression in UC patients may be related to hypomethylation of IL-6 gene promoter region.3.There is a decrease in the enzymatic activity of colonic mucosal DNMTs in patients with UC,and this may lead to a decrease in the methylation level of the IL-6 promoter region.