Correlation Analysis Of Protein Kinase Lyn And UACR In Type 2 Diabetes Mellitus

Background:Lyn,belongs to Src family of non-receptor protein tyrosine kinases family.In basic experiments,Lyn affects the progression of chronic kidney disease by regulating inflammation.In STZ-induced diabetic mice,treatment with the Src family kinase inhibitor PP2 reduced albuminuria.Therefore,this study elucidated Lyn expression in peripheral blood mononuclear cells and renal tissues of patients with type 2diabetes mellitus,and explored its correlation with albuminuria,serum inflammatory cytokines and urinary renal tubular injury biomarkers.Methods:According to the urinary microalbumin/urine creatinine ratio(u ACR),102 T2DM patients were divided into three groups:normoalbuminuria group(u ACR<30mg/g,n=32),microalbuminuria group(30mg/g≤u ACR<300mg/g,n=36)and macroalbuminuria group(u ACR≥300 mg/g,n=34).Twenty-one healthy volunteers were recruited as healthy control(HC).The basic data and biochemical indexs of all subjects were collected.Whole blood,serum and urine of all subjects were collected for analysis.Lyn expression in peripheral blood mononuclear cells(PBMCs)was measured by Western-blot and RT-PCR.The expressions of TNF-α,MCP-1 and IL-1βin serum were analyzed by ELISA.The expression of NGAL and RBP in urine was detected by immunoturbidimetry.Lyn expression was measured by immunohistochemistry in kidney tissues of 11patients with diabetic nephropathy confirmed by renal biopsy and 5 patients without diabetes(adjacent tissue of renal carcinoma confirmed as normal renal tissue by histology).Results:(1)In three groups of type 2 diabetic patients,Lyn mRNA and protein levels were the highest in the macroalbuminuria group.Lyn expression level in the macroalbuminuria group was compared with that in the normo-albuminuria group and the microalbuminuria group,and the differences between the groups were statistically significant(P<0.05).Lyn mRNA level in PBMC increased with the increase of albuminuria in type 2 diabetic patients.(2)Spearman or Pearson correlation analysis showed that Lyn mRNA levels in PBMC was positively correlated with u ACR,it was also positively correlated with inflammatory cytokine IL-1β,TNF-α,MCP-1 and renal tubular injury biomarkers of NGAL and RBP.(3)Multiple linear regression showed that Lyn was independently associated with u ACR.Lyn showed positive correlation with Ln(u ACR)in T2DM patients(r=0.743,p<0.001).After multiple linear regression analysis,the regression equation of Ln(u ACR)was:Y=0.619+0.623*Lyn+0.180*SBP-0.187*ALB,R~2=0.619.Lyn was also independently correlated with inflammatory cytokine IL-1β,renal tubular injury biomarkers of NGAL and RBP.(4)Logistic ordered muiti-classification regression analysis confirmed that Lyn was still a risk factor for increased albuminuria after adjustment for confounding factors such as diabetic duration,blood glucose,lipids,blood pressure,kidney function.(5)ROC curve analysis showed that Lyn could be used as an indicator of albuminuria.Lyn’s optimal cut-off value for the diagnosis of microalbuminuria in T2DM patients was 2.025,AUC was 0.844,sensitivity was 75.71%,specificity was78.13%.(6)Immunohistochemistry confirmed that the protein kinase Lyn expression was increased in the renal tissues of diabetic nephropathy patients,compared with non-diabetic patients,there was significant difference in two group(P<0.01).Conclusion:Protein kinase Lyn expression was measured in PBMC and renal biopsy tissues in patients with type 2diabetes,and increased with the increase of albuminuria.It is associated with inflammation and renal tubular injury.It is a potential biomarker of the severity of diabetic nephropathy.