Effect Of Chromium And Iron On Glucose Metabolism And Its Mechanism

Background Type 2 Diabetes Mellitus(T2DM)is a major public health problem affecting the people’s health at home and abroad.With economic development and population aging,the prevalence of T2 DM is increasing year by year,which seriously affected people’s quality of life and bringed heavy financial burden to individuals,families and society.Genetic factors,overweight,obesity and unhealthy lifestyle are the main risk factors for T2 DM.In recent years,a great deal of studies have found that trace elements could affect glucose metabolism,which was closely related to the prevalence of T2 DM.Many studies have showed that chromium had protective effect on glucose metabolism abnormality,while iron overload was a risk factor for glucose metabolism abnormality.However,the effects of joint action between chromium and iron on glucose metabolism remains unclear.In this study,the effects of chromium and iron on glucose metabolism and the potential mechanism were explored through case-control study,bioinformatics analysis and in vitro cell experiment,so as to provide basis for further study on the pathogenic factors,prevention and control of T2 DM.Part I The association of chromium,iron and type 2 diabetes mellitusObjective To investigate the association between chromium,iron and T2 DM in a rural population of Ningxia.Methods We conducted a case-control study.In the baseline data of the China North-West Natural Population Cohort: Ningxia Project(CNC-NX),according to the 1999 WHO diagnostic criteria for T2 DM and the inclusion and exclusion criteria of this study,268T2 DM,224 impaired fasting glucose(IFG)and 312 healthy people were recruited according to frequency matching by age and sex.Demographic information,lifestyle,height,weight,resting blood pressure were collected from questionnaires and physical examinations.Blood samples and urine samples were collected to detect fasting blood glucose(FBG),fasting serum insulin(FINS),total cholesterol(TC),triglyceride(TG),high-density lipoprotein cholesterol(HDL-C),low-density lipoprotein cholesterol(LDL-C).The concentration of chromium and iron in serum and urine were determined by ICPMS.Spearman correlation analysis and generalized linear model(GLM)were used to analyze the association between chromium,iron and T2 DM.Results Serum chromium in T2 DM group was significantly lower than that in IFG group and healthy control group(P<0.05).There was a negative correlation between serum iron and FINS(P<0.05)and a positive correlation between urinary iron and FINS(P<0.05).After controlling for age,sex,TC,TG,HDL-C and LDL-C,the group with the highest level of serum chromium had a 46% lower risk of T2 DM compared with the group with the lowest level of serum chromium.The interaction between serum chromium and serum iron on T2 DM was statistically significant(P=0.023),and there are interactions between multiple levels of serum chromium and serum iron(P< 0.05),and the OR value is less than 1.Conclusion There was a negative association between serum chromium and T2 DM.Multiple levels of serum chromium and serum iron interacted on T2 DM,which presenting antagonistic effect.Part II Bioinformatics analysis of the association between chromium,iron and type 2 Diabetes MellitusObjective To explore the common signaling pathway of chromium and iron with T2 DM by bioinformatics methods.Methods The gene expression profiles associated with T2 DM,chromium and iron were obtained from Gene Expression Omnibus(GEO)and Comparative Toxicogenomics Database(CTD).The differentially expressed genes(DEGs)related to T2 DM and chromium,T2 DM and iron were analyzed,respectively.Then GO enrichment analysis and KEGG signaling pathway analysis were performed.The obtained signaling pathways were then compared to find the common signaling pathways of chromium and iron with T2 DM.Results 191 DEGs related to T2 DM and chromium were screened out,of which 131 were up-regulated and 60 were down-regulated.47 DEGs related to T2 DM and iron were screened out,of which 28 were up-regulated and 19 were down-regulated.GO enrichment analysis and KEGG signaling pathway analysis were carried out for the above DEGs,respectively.The obtained signaling pathways were then compared.It was found that the effect of chromium and iron with T2 DM had common signaling pathways,which including PI3K/Akt signaling pathway.Conclusion PI3K/Akt might be a common signaling pathway on the effect of chromium and iron with T2 DM.This needed to be further studied in biological experiments.Part III The effect and mechanism of chromium and iron on glucose metabolism through ROS mediated PI3K/Akt/GLUT4 signaling pathwayObjective To investigate the effect of chromium and iron on glucose metabolism and its potential mechanism through in vitro cell experiment and to explore whether chromium and iron impact on glucose metabolism by PI3K/Akt/GLUT4 signaling pathway.Methods The C2C12 cells were cultured in DMEM+10% fetal bovine serum for 24 h.Cell viability was detected by CCK8 method.The C2C12 cells were treated with dimethyl sulfoxide(DMSO≤0.1%),FAC(100μM),Cr Pic(100n M),FAC(100μM)+ Cr Pic(100n M),Cr Pic(100n M)+LY294002(PI3K inhibitor,5μM),and FAC(100μM)+ Recilisib(PI3K activator,20μM)for 24 h.Insulin-stimulated glucose uptake and intracellular ROS level were measured by fluorescent probe 2-NBDG and DCFH-DA,respectively.The protein expression levels of PI3 K,Akt,GLUT4 were detected by western blotting.Results On the basis of CCK8 test,combined with references and exposure levels of trace element in human body,100μM FAC,100 n M Cr Pic,5μM LY294002 and 20μM Recilisib for 24 h were determined as the intervention conditions of C2C12 cells in this experiment.Insulin-stimulated glucose uptake were significantly higher in the Cr Pic group and lower in FAC group than that in the control group(P<0.05).Insulin-stimulated glucose uptake in Cr Pic + FAC group was significantly higher than that in FAC group(P<0.05).ROS levels were significantly increased in the FAC group compared with the control group(P<0.05).ROS levels in Cr Pic + FAC group was significantly lower than that in FAC group(P<0.05).Compared with the control group,the p-PI3K/PI3 K,p-Akt/Akt and GLUT4 were significantly decreased in the FAC group(P<0.05).The p-PI3 K /PI3 K,p-Akt/Akt and GLUT4 in Cr Pic + FAC group were significantly higher than those in FAC group(P<0.05).Conclusions We found that FAC inhibited insulin-stimulated glucose uptake through the ROS-mediated PI3K/Akt/GLUT4 signaling pathway in C2C12 cells under our experimental conditions.Cr Pic improved iron-inhibited insulin-stimulated glucose uptake through the ROS-mediated PI3K/Akt/GLUT4 signaling pathway.This study suggested that chromium might have a protective effect on iron induced glucose metabolism abnormality.The mechanism might be related to the up-regulation of ROS-mediated PI3K/Akt/GLUT4 signaling pathway.