| Backgrounds:Chronic complications in type 2 diabetes are macrovascular complications including coronary heart disease,cerebral infarction as well as peripheral artery atherosclerosis and microvascular complications including nephropathy,retinopathy as well as neuropathy,which lead to a high incidence of death and disability in diabetic patients.The mechanism of diabetic vascular complications is unknown.Osteoprotegerin,a recently identified glycoprotein belonging to the tumor necrosis factor receptor superfamily,was originally discovered as an inhibitor of bone resorption.It has been proposed that osteoprotegerin may be involved in the development of calcifications in the arterial wall,where the molecule is present in concentrations comparable with those in bone.Supporting this idea, studies have shown that expression of osteoprotegerin and production of the protein are altered in arterial areas with calcification.Recently,some studies have indicated that osteoprotegerin also acts as an important regulatory molecule in the vasculature, and increased plasma osteoprotegerin concentrations are associated with coronary artery disease in nondiabetic patients.In some more recent studies in diabetic subjects, a strong association between plasma levels of osteoprotegerin and coronary artery disease was observed.Furthermore osteoprotegerin gene polymorphism(T-to-C at 950) was reported to be associated with coronary heart disease,patients with C/C genotype have higher coronary heart disease risk and higher serum osteoprotegerin levels.Whether serum osteoprotegerin level and osteoprotegerin gene polymorphism are associated with macroangiopathy in Chinese type 2 diabetes is unknown,so we investigated the serum osteoprotegerin level and osteoprotegerin gene polymorphism in type 2 diabetes,whether serum osteoprotegerin level is associated with microvascular complications,only one article reported the serum osteoprotegerin level was increased in diabetic patients with microalbuminuria and retinopathy.At present,no research on the relationships between the degree of diabetic nephropathy, retinopathy and osteoprotegerin was reported.So in this study,we also investigated the relationships between serum osteoprotegerin level and diabetic nephropathy, retinopathy as well as their severity.Objective:1.To investigate the relationships between serum osteoprotegerin level and osteoprotegerin gene polymorphisms with macroangiopathy in type 2 diabetes patients.2.To investigate the serum osteoprotegerin level and osteoprotegerin expression in kidney biopsy tissue in type 2 diabetes with nephropathy.3.To investigate the serum osteoprotegerin level and diabetic retinopathy in type 2 diabetes.Methods:1.Serum osteoprotegerin level was measured by enzyme-linked immunoassay(ELISA) and osteoprotegerin gene polymorphisms(T-to-C at 950) was examined by PCR and restriction enzyme technique in 86 type 2 diabetes with macrovascular complications,82 patients without macrovascular complications and 40 healthy persons.2.Serum osteoprotegerin level was measured by ELISA in 38 type 2 diabetes with normoalbuminuria,36 patients with microalbuminuria,36 patients with macroalbuminuria and 40 healthy persons.Part of diabetes patients with nephropathy were performed kidney biopsy by ultrasound guide.The osteoprotegerin expression in kidney biopsy tissue is examined by immunohistochemistry.3.30 type2 diabetes patients with proliferative retinopathy,30 patients with background retinopathy and 36 patients without retinopathy were collected for the research on the relationship between serum osteoprotegerin and diabetic retinopathy.Results:Part 1:1.The serum osteoprotegerin level in diabetic patients with macroangiopathy was 4.16±0.65 ng/l,which was significantly higher than that in patients without macroangiopathy(2.75±0.59) and control subjects(2.29±0.37 ng/l,p＜0.01).2.Correlation analysis showed that the serum osteoprotegerin has significant positive correlation with the FPG(r=0.243,p＜0.01),2hPG(r=0.237,p＜0.01),HbAlC (r=0.361,p＜0.001),HOMA-IR(r=0.252,p＜0.01),hsCRP(r=0.585,p＜0.001),and no correlation with age,BMI,blood pressure,blood lipid profiles and fasting insulin.3.Gene polymorphisms results showed that C/C genotype was more prevalent in patients with maeroangiopathy than without macroangiopathy(24.4%versus 11%, p＜0.05) and C allele prevalence was also higher than that in patients without macroangiopathy(40.7%versus 29.9%,p＜0.05).Subjects with C/C genotype(3.96±0.85 ng/l) have higher serum osteoprotegerin level than those with T/T(3.36±0.93 ng/l ) and T/C(3.37±0.94) ng/l genotype.(p＜0.05).4.Multivariate logistic regression analysis revealed that serum osteoprotegerin levels and C/C genotype were independently associated with the presence of macroangiopathy in patients with type 2 diabetes.Part 2:1.The serum osteoprotegerin level in macroalbuminuria group was 4.45±0.76 ng/l, which was significantly higher than that in microalbuminuria group(3.62±0.70) and normoalbuminuria group(2.77±0.78 ng/l)(p＜0.01).And the serum osteoprotegerin level in microalbuminuria group was also higher than that in normoaibuminuria group(p＜0.01).2.Correlation analysis showed that the serum osteoprotegerin has significant positive correlation with the FPG(r=0.223,p＜0.05),2hPG(r=0.298,p＜0.01),HbAlC (r=0.520,p＜0.001),HOMA-IR(r=0.257,p＜0.01),hsCRP(r=0.360,p＜0.001) and UAER(r=0.639,p＜0.001).3.Multivariate regression analysis revealed that serum osteoprotegerin level was independently effective factor for UAER in type 2 diabetes.4.The immunohistochemistry results showed that positive immunostaining for osteoprotegerin was observed in the renal tubule cells and not in glomerulus,and the osteoprotegerin expressed level was higher in macroalbuminuria group than that in microalbuminuria group. Part 3:1.The serum osteoprotegerin level in proliferative diabetic retinopathy group was 4.07±1.08 ng/l,which was significantly higher than that in background retinopathy group(3.57±0.96) and no retinopathy group(2.77±0.78 ng/l)(p＜0.01).And the serum osteoprotegerin level in background retinopathy group was also higher than that in no retinopathy group(p＜0.01).2.Correlation analysis showed that the serum osteoprotegerin has significant positive correlation with the FPG(r=0.263,p＜0.01),2hPG(r=0.305,p＜0.01),HbAlC (r=0.377,p＜0.001),hsCRP(r=0.453,p＜0.001) and HOMA-IR(r=0.324,p＜0.001).and no correlation with age,BMI,blood pressure,blood lipid profiles and fasting insulin.3.Multivariate logistic regression analysis revealed that serum osteoprotegerin level was independently associated with diabetic retinopathy in patients with type 2 diabetes.Conclusions:1.Serum osteoprotegerin levels were significantly increased in type 2 diabetes with macroangiopathy and microangiopathy,and there is a independently significant association between serum osteoprotegerin levels and the presence and severity of diabetic vascular complications,which supports the growing concept that osteoprotegerin acts as an important regulatory molecule in the vasculature of diabetes.2.The serum osteoprotegerin level has significant positive correlation with the FPG,2hPG,HbAlC,hsCRPand HOMA-IR.,indicating that the high serum osteoprotegerin levels in diabetic vascular complications are associated with diabetic control,insulin resistance and inflammation.3.Osteoprotegerin gene polymorphism at 950 was associated with macrovascular complications in chinese type 2 diabetes.This polymorphism may play a role in the development of macroangiopathy in type 2 diabetes.4.Positive immunostaining for osteoprotegerin was observed in the renal tubule cells and not in glomerulus,and the osteoprotegerin expressed level was higher in macroalbuminuria group than that in microalbuminuria group,indicates that renal tubule cells may be the important source of elevated serum osteoprotegerin level in type 2 diabetes with nephropathy.
|
PDF Full Text Request