| Objective: Gestational diabetes mellitus(GDM)represents the most common complication associated with pregnancy.Glucose intolerance induced by decreased insulin sensitivity and insulin resistance is the main mechanism of GDM.However,the pathogenesis of GDM has not been fully elucidated,and there is no effective drug against GDM.Clinal and animal studies found that obesity and adipose tissue play key role in the development of GDM.The Fibroblast growth factor 21(FGF21)is a hepatic metabolic hormone that exerts pleiotropic effects on glucose homeostasis and insulin sensitivity through its actions in adipose tissue.Invivo experiments demonstrated that FGF21 can induce the generation and secretion of adiponectin in adipose tissue,which can improve metabolic disorders,such as glucose intolerance,overweight and obesity.Thus,this study aims to investigate whether the action of FGF21 is altered in white adipose tissue in women with GDM,which in turn contributes to GDM development.Aims:1.To find different metabolic hormones between women with GDM and with normal glucose tolerance(NGT).2.To find the correlations between metabolic hormones,such as FGF21,adiponectin,and related indicators of glucose intolerance,for instance blood glucose,insulin resistance and homeostasis model assessment of insulin resistance(HOMA-IR).3.To analyze the correlation between adipose tissue and glucose intolerance during pregnancy.4.To demonstrate the functional and molecular mechanism of FGF21 downstream signaling disorder in Subcutaneous white adipose tissue(sWAT)of pregnant women with GDM.In conclusion,this project aimed to provide basic theory for the research and development of GDM based on metabolic hormones,such as FGF21 and adiponectin.Methods:1.103 GDM women and 402 subjects with normal glucose tolerance(NGT)were recruited for measurement of circulating FGF21 and Adiponectin,metabolic characteristics were collected for the further analysis.Circulating FGF21 and adiponectin levels were detected with enzyme-linked immunosorbent assay(ELISA)kits.F test was used for homogeneity of variance and T test was used for comparison between 2 groups.P < 0.05 means significant difference between 2 groups.2.Circulating insulin levels were detected with ELISA kits.The correlations between metabolic hormones,such as FGF21,adiponectin,and related indicators of glucose intolerance,for instance blood glucose,insulin resistance and homeostasis model assessment of insulin resistance(HOMA-IR)were analyzed by Pearson’ correlation.Further correlation analysis with the elimination of prepregnancy BMI and age were calculated by Partial Correlation analysis.P < 0.05 were considered statistically significant and stronger correlations were regarded as correlation coefficient is closed with 1 or-1.3.To analyze the correlation between prepregnancy BMI and blood glucose during pregnancy with Pearson’s Correlation analysis method.sWAT obtained from the site of incision during cesarean delivery was collected for the observation of pathological and morphological changes by Histopathological method.4.sWAT obtained from the site of incision during cesarean delivery was subjected to the determination of fibroblast growth factor receptor-1(FGFR1)and β-Klotho expression levels and explant culture to evaluate FGF21 sensitivity.sWAT was treated with recombinant FGF21(rhFGF21)in ex-plant culture,and protein and mRNA levels of downstream targets of FGF21 in adipocytes were detected,as well as adiponectin levels in culture medium.Results:1.Clinical study that aimed to find different metabolic hormones between women with GDM and with normal glucose tolerance(NGT).Compared with NGT subjects,pregnancy age,prepregnancy BMI,blood glucose levels of OGTT in 24-28 weeks during pregnancy,circulating insulin and HOMA-IR were significantly increased in GDM patients.(P < 0.05).Notably,GDM patients had a significantly higher serum FGF21 level than NGT subjects.(P < 0.001)In contrast,circulating level of adiponectin was significantly lower in GDM women.(P < 0.001)Accordingly,the ratio of FGF21 to adiponectin in GDM women was approximately 3-fold higher than NGT group.Due to its relatively reliable performance,FGF21/adiponectin ratio may act as a potential biomarker for GDM.(ROC = 0.6641,95% CI 0.6033 – 0.7250;P < 0.0001)2.The correlations analysis between metabolic hormones and related indicators of glucose intolerance.In the whole cohort,serum level of FGF21 and FGF21/Adiponectin ratio was significantly and positively correlated with fasting blood glucose,1-hour and 2-hour glucose levels during OGTT;whereas serum level of adiponectin was inversely correlated with fasting blood glucose,1-hour,and 2-hour glucose level during OGTT.(P < 0.001)Serum levels of adiponectin were inversely correlated with fasting serum insulin and homeostasis model assessment of insulin resistance(HOMA-IR)in whole cohort and NGT peers,but not in GDM patients.After the adjustment for age and prepregnancy BMI,the correlation between circulating levels of FGF21,adiponectin,FGF/adiponectin ratio and FPG,1-,2-hour glucose levels remain significant(all P < 0.01).Intriguingly,only adiponectin showed significant correlation with HOMA-IR in whole cohort,which diminished in subgroup analysis in both GDM and NGT subjects.3.To demonstrate pathological and morphological changes of sWAT in GDM patientsCompared with NGT subjects,adipose tissue was significantly expanded in GDM patients.Prepregnancy obesity and expansion of adipocytes were significantly correlated with prevalence of GDM.(P < 0.001)Pregnancy BMI has a significant correlation with fasting blood glucose in OGTT during pregnancy.4.Verification of FGF21 downstream signaling disorder in sWAT of GDM patientsIn sWAT from GDM patients,FGFR1 and β-Klotho,which form a receptor complex for FGF21,were dramatically reduced in couple with decreased levels of Adiponectin and transcriptional abundance of downstream genes of FGF21,such as pERK 1/2.5.To prove the dysfunction of FGF21 in regulating sWAT of GDM patients with ex-plant culture of sWAT.In response to recombinant FGF21 stimulation during explant culture of sWAT,Adiponectin production,ERK1/2 phosphorylation,and the expression of FGF21-induced genes were significantly impaired in GDM patients relative to NGT subjects.Conclusions:1.Compared to NGT women,GDM patients were found significant difference of circulating FGF21,Adiponectin and FGF21/Adiponectin ratio.2.There was a close and independent correlation between FGF21,Adiponectin and blood glucose metabolism during pregnancy.3.The natural changes of adipose tissue in obesity was closely associated with the development of GDM.4.FGF21-evoked downstream intracellular events were dampened in sWAT in GDM patients.5.FGF21-induced adiponectin biosynthesis in sWAT and its release into bloodstream were dramatically inhibited in GDM patients relative to NGT controls.In summary,the present study provides the first clinical demonstration of the coexistence of elevated FGF21 but decreased adiponectin concentrations in blood,relative down-regulation of FGF21’s receptor and co-receptor coupled with blunted induction of intracellular downstream events in sWAT,and the impairments in FGF21-evoked adiponectin production and ERK1/2 activation in GDM patients.These findings are strong evidence of a “FGF21 resistance” state in sWAT in GDM in a clinical setting.Thus,the present study not only provides a potential mechanism that links adipose tissue dysfunction and glucose intolerance in GDM. |
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