Fetuin-A Might Be A New Marker For Disease Severity Of Diabetic Nephropathy

Objective : Pathogenesis of diabetic nephropathy(DN)is one of the severe chronic complication of diabetes.Currently there is no precise marker in predicting its development.Microalbuminuria(MAU)is recommended the only diagnostic marker for diagnosis of DN.Recently,many new biomarkers were proposed as new predicting marker,such as Cystatin C,transforming growth factor-b,and8-hydroxy-29 deoxyguanosine.Recently Fetuin-A has been proposed as marker of ectopic calcium deposition,insulin resistance.In order to delineate if Fetuin-A could be used as a marker to predict the development of DN,tissue distribution of Fetuin-A in the mice model of diabetic in mice was analyzed,and the association of serum and urine Fetuin-A with severity of diabetic nephropathy were studied.Methods:1.Animal studyEight-week mice were purchased,five non-obese Akita mice were used as diabetes model,and five BL6 mice as non-diabetic control.After two weeks' accommodation,the mice were killed.Liver and kidney were excised and homogenated,protein was extracted.The content of Fetuin-A in liver and kidney was analyzed by Western blot.2.Clinical studyA total of 648 Japanese patients with type 2 diabetes were recruited.Diabetic nephropathy was diagnosed according to the definition and classification of chronic kidney disease [Kidney Disease: Improving Global Outcomes(KDIGO)],urinary albumin-creatinine ratio(UAlb/Cre)and estimated glomerular filtration rate(e GFR)as a criteria.Critieria for Ualb/Cre: stage: A1(<30 mg/g),A2(30–299 mg/g)and A3(>300 mg/g).The e GFR staging was G1(> 90 ml/min/1.73m2),G2(60–89ml/min/1.73m2),G3(30–59 ml/min/1.73m2),and G4(15–29 ml/min/1.73m2).Patients with e GFR<15 ml/min/1.73m2 or under dialysis were excluded.Collected patients' age and BMI.Overnight fasting serum levels of fasting plasma glucose(PG),Hb A1 c,total cholesterol(TC),low density lipoprotein cholesterol(LDL-C),high density lipoprotein cholesterol(HDL-C),triglycerides(TG),uric acid(UA),serum creatinine(SCr),urine creatinine(UCr),and urea nitrogen(UN)were analyzed.Urinary albumin was measured in random spot urine samples by standard immuno-nephelometric assay.The UAlb/Cre and e GFR was calculated.Sample of urinary and serum samples were stored in-80? until determination,and Fetuin-A was measured with a commercial ELISA kit for Human Fetuin-A.Statistics was analyzed with SPSS software(IBM,ver 23).Results:1.Content of Fetuin-A in mice liver and kidneyFetuin-A level in liver of Akita and BL6 mice was not significant different.Fetuin-A was significantly higher in kidney of Akita than that of BL6.2.Clinical data comparisonVarious clinical parameters in UAlb/Cre and eGFR stages were compared by Kruskal-Wallis test.In UAlb/Cre stages(A1,A2,A3),SBP,SCr,UN,UA,e GFR were significantly changed(P<0.001).In e GFR stages(G1,G2,G3,G4),age,DBP,Hb A1 c,PG,SCr,UN,UA,TG,LDL-C and UAlb/Cre were significantly changed(P<0.001).3.Study the association of serum and urine Fetuin-A with clinical measures,metabolites,and severity of diabetic nephropathyUnivarite spearman correlation analysis found urinary Fetuin-A was related to age (r=0.161,P<0.01),UAlb/Cre(r=0.397,P<0.001),BUN(r=0.19,P<0.001),SCr(r=0.167,P<0.001),e GFR(r=-0.192,P<0.001)and SBP(r=0.17,P<0.001),Serum Fetuin-A is related to age(r=-0.11,P<0.001),BMI(r=0.163,P =0.001),TG(r=0.126,P =0.007)and HDL(r=-0.096,P =0.042).Urinary Fetuin-A was significantly increased during the progression of UAlb/Cre stages from A1 to A3(P=1.44×10-24)and e GFR stages from G1-G4(P=7.12×10-9)by Kruskal-Wallis test.But serum Fetuin-A didn't show a significantly change(P>0.05).Multivariate Logistic linear regression analysis found TG(?=0.125,P<0.05)and BMI(?=0.124,P<0.05)were independent variables for serum Fetuin-A.UAlb/Cre(?=0.669,P<0.001)and e GFR(?=-0.087,P<0.05)were independent variable for urine Fetuin-A.Fetuin-A(?=-0.143,P<0.05)and UAlb/Cre(?=-0.264,P<0.001)was an independent variable for e GFR.Conclusions:Fetuin-A is expressed uniquely in kidney,and urine Fetuin-A would might be used as a new biomarker to predict the severity of diabetic nephropathy.