Diabetic Nephropathy Subjects Research Articles

Probiotic Soy Milk Consumption and Renal Function Among Type 2 Diabetic Patients with Nephropathy: a Randomized Controlled Clinical Trial.

Diabetic nephropathy (DN) is one the most important complications of diabetes leading to end-stage renal disease. Dietary approaches have been considered to control of the kidney function deterioration among these patients. The aim of the present study was to determine the effects of fortified soy milk with Lactobacillus plantarum A7 on renal function biomarkers in type 2 DN patients. Forty-eight DN subjects were attended to this parallel randomized trial study. Participants were randomly assigned to consume a diet containing 200mL/day probiotic soy milk in intervention group or soy milk in the control condition for 8weeks. An inflammatory adipokine-Progranulin (PGRN), a cytokine receptor-soluble tumor necrosis factor receptor 1 (sTNFR1), and serum levels of Neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C (Cys-C) as the new renal function biomarkers were measured after 8weeks of intervention according to the standard protocol. Our analysis showed that consumption of probiotic soy milk resulted in a significant reduction in the Cys-C and PGRN levels compared with the soy milk (P=0.01) in the final adjusted model. In addition, after adjustment for age, weight, and energy intake, a marginally significant in the NGAL level was seen between two groups (P=0.05). However, there was no significant differences on the sTNFR1concenteration between two groups (P=0.06). Overall, intake of probiotic soy milk may have a beneficial effect on the renal function in patients with DN.

Clinical Implication of Cystatin C and β2-Microglobulin in Early Detection of Diabetic Nephropathy.

Diabetic nephropathy (DN) is one of the major late complications of type 2 diabetes mellitus (T2DM). The aim of this study was to evaluate the efficiency of cystatin C (cysC) and β2-microglobulin (β2-MG) in diagnosing early DN and to identify the optimal threshold in the Chinese patients. T2DM patients were divided into 102 non-DN subjects, 60 early DN subjects, and 38 clinical DN subjects. Blood and urine measurements were compared among the groups. Receiver-operating characteristic (ROC) curves and areas under the curve (AUC) were calculated to demonstrate the prediction values of the variables. Stepwise regression analysis showed that the levels of cysC and β2-MG were associated with early DN. The AUC was 0.874 for cysC and 0.792 for β2-MG. The threshold based on the ROC curve had the best diagnostic performance compared with the threshold with respect to mean + SD (standard deviation) and parallel tests. A high sensitivity of 91.67% was achieved at the cysC threshold of 0.91 mg/L with a moderate specificity of 76.47% and a sensitivity of 80.00% for the β2-MG threshold of 1.86 mg/L with a specificity of 67.65%. The findings suggest that the cysC threshold of 0.91 mg/L may be acceptable as a diagnostic criterion for early DN in the Chinese patients. The results also suggest that for T2DM patients the normal reference range of cysC should be set lower in favor of early DN screening.

Serum Interleukin-18 and Its Gene Haplotypes Profile as Predictors in Patients with Diabetic Nephropathy.

BACKGROUND:Diabetic nephropathy (DN) is known as an acute microvascular complexity as a subsequence progression in diabetes mellitus type 1 and 2. Many evidence pointed that the proinflammatory cytokine Interleukin (IL)-18 might be involved in the pathogenesis of DN.AIM:The current study aimed to evaluate the association of serum IL-18 and its promoter gene polymorphisms with diabetic nephropathy.METHODS:This study included 62 diabetic nephropathy patients (DN group) compared to 52 diabetes mellitus patients (DM group). The two groups were subjected to anthropometry assessment, molecular studies including SNP genotyping by RFLP and finally statistical analysis.RESULTS:The assessment of the serum IL-18 level and the frequencies of its allele and haplotype: -137G/C, -607C/A and -656G/T among the DN and DM subjects revealed that -137G allele has significant variation between DN and DM subjects (about 80.8%, P = 0.05) but, no significant variation in -607 or -656 alleles IL-18 gene promoter.CONCLUSION:These data confirm the impact of high serum IL-18 and the haplotype of the polymorphism located in the promoter region of the IL-18 gene with the DN.

Identification of NOD2 as a novel target of RNA-binding protein HuR: evidence from NADPH oxidase-mediated HuR signaling in diabetic nephropathy

Although our recent studies have demonstrated that NOD2 is one of the critical components of a signal transduction pathway that links renal injury to inflammation in diabetic nephropathy (DN), the regulatory mechanisms for NOD2 expression under hyperglycemia have not yet been elucidated. Considering that NOD2 mRNA from different species bears a long 3′-UTR with various AU-rich elements, the present study was designed to investigate the potential contribution of the RNA-binding protein human antigen R (HuR) on the posttranscriptional regulation of NOD2 expression. In this study, we first found upregulation of HuR in the kidney from DN subjects, which was correlated with proteinuria, indicating a role for HuR in the pathogenesis of DN. In vitro, high glucose (HG) induced a distinct increase in cytoplasmic HuR in rat glomerular mesangial cells. By RNA EMSA, we found that HuR bound to the 3′-UTR of NOD2, and HuR silencing reduced HG-induced NOD2 expression and mRNA stability. Mechanistically, we further found that NADPH oxidase-mediated redox signaling contributed to the expression and translocation of HuR and NOD2 mRNA stability. Finally, we evaluated the role of HuR showing that in vivo gene silencing of HuR by intrarenal lentiviral gene delivery ameliorated renal injury as well as reducing NOD2 expression in diabetic rats. Collectively, our studies demonstrate that HuR acts as a key posttranscriptional regulator of NOD2 expression, suggesting that targeting of HuR–NOD2 signaling might be crucial for the treatment of DN.

Genetic variants of ACE (Insertion/Deletion) and AGT (M268T) genes in patients with diabetes and nephropathy.

Diabetes mellitus (DM) has been a growing epidemic worldwide and poses a major socio-economic challenge. The leading cause of DM death is nephropathy due to end-stage renal disease (ESRD). This study aims to identify the possible association of I/D variants of the ACE gene and M268T (rs699) of the AGT gene of renin-angiotensin-aldosterone system (RAAS). Study subjects include 115 patients with DM, 110 with diabetic nephropathy (DN) and 110 controls. Fasting blood samples were collected for biochemical analyses and PCR amplification of specific regions of the ACE and AGT genes using primers. The distribution of ACE (I/D) II 28.8%, ID 35.6% and DD 35.6% while in DN II 24.5%, ID 41% and DD 34.5%. The AGT (M268T) genotypes were distributed in DM as TT 30.4%, MT 66.9% and MM 2.6% while in DN subjects TT 56.4%, MT 42.7% and MM 0.9%. Significant differences were observed in the DD genotype and D allele of the ACE gene and the TT genotype and T allele of AGT genes between diabetic patients with and without nephropathy. The study may conclude that the D allele polymorphism in the ACE gene and the T allele polymorphism in AGT gene may be considered as genetic risk factors for the development of nephropathy in diabetes.

Serum CXCL16 as a Novel Marker of Renal Injury in Type 2 Diabetes Mellitus

BackgroundSoluble C-X-C chemokine ligand 16 (CXCL16), a scavenger receptor for oxidized low density lipoprotein, has been shown to promote atherogenic effects in vivo and to predict long-term mortality in acute coronary syndrome. The aim of this study was to explore the association of circulating CXCL16 levels with diabetic subjects with and without renal disease.Methodology/Principal FindingsOne hundred twenty Chinese subjects, which included patients with type 2 diabetes mellitus (T2DM), diabetic nephropathy (DN), and CKD, as well as healthy controls, were enrolled in this study. Serum CXCL16 levels were examined by immunoassay and other clinical biochemical parameters were tested based on standard methods. Our results indicated that, HDL and LDL cholesterol levels are significantly different in DN but not in T2D patients in comparison with healthy subjects. On the other hand, Serum CXCL16 levels were significantly increased in DN subjects compared with age and gender matched healthy and T2DM subjects (p<0.05 respectively). However, no significant changes in serum CXCL16 levels were found between T2DM and healthy subjects. Furthermore, serum CXCL16 concentration negatively correlated with estimated glomerular filtrate rate, creatinine clearance rate and blood albumin, and positively with 24 h proteinuria, blood urea nitrogen (BUN), creatinine, and uric acid after adjusting for age, gender and BMI in subjects with DN. Multiple stepwise regression analyses indicated that serum CXCL16 levels were independently associated with serum 24 h proteinuria, and BUN (p<0.05 respectively).ConclusionSerum CXCL16 may be an indicator of renal injury in subjects with T2DM. Understanding the exact mechanism of elevated CXCL16 in subjects with DN requires further study.

Association ofInterleukin-6 −174 G&gt;CPromoter Polymorphism with Increased Risk of Type 2 Diabetes Mellitus Patients with Diabetic Nephropathy in Turkey

Diabetic nephropathy (DN) is a serious complication of diabetes mellitus. We aimed to evaluate the interleukin (IL)-6 gene polymorphisms in type 2 DN and control subjects. The patients selected from the Department of Endocrinology and Metabolism Diseases included 43 type 2 diabetes mellitus patients without DN and 43 type 2 diabetes mellitus patients with DN and 340 healthy normal controls. All subjects underwent venous blood drawing for complete hormonal assays, lipid profile, glucose, and insulin and Il-6 gene polymorphism genetic analysis. IL-6 -174 G>C genotype distribution was different between the control group and the type 2 diabetes mellitus patients (p=0.004). The higher frequency of the polymorphic G allele was also similar for the group with type 2 diabetes mellitus as for the control group. The frequency of the polymorphic G allele was 83.9% in diabetic patients with nephropathy versus 70.9% in those without nephropathy (p=0.039). We suggest that the -174 G>C polymorphism of the IL-6 gene is an independent risk factor for DN in Turkish type 2 diabetes mellitus patients.

NOD2 promotes renal injury by exacerbating inflammation and podocyte insulin resistance in diabetic nephropathy

An increasing number of clinical and animal model studies indicate that activation of the innate immune system and inflammatory mechanisms are important in the pathogenesis of diabetic nephropathy. Nucleotide-binding oligomerization domain containing 2 (NOD2), a member of the NOD-like receptor family, plays an important role in innate immune response. Here we explore the contribution of NOD2 to the pathogenesis of diabetic nephropathy and found that it was upregulated in kidney biopsies from diabetic patients and high-fat diet/streptozotocin-induced diabetic mice. Further, NOD2 deficiency ameliorated renal injury in diabetic mice. In vitro, NOD2 induced proinflammatory response and impaired insulin signaling and insulin-induced glucose uptake in podocytes. Moreover, podocytes treated with high glucose, advanced glycation end-products, tumor necrosis factor-α, or transforming growth factor-β (common detrimental factors in diabetic nephropathy) significantly increased NOD2 expression. NOD2 knockout diabetic mice were protected from the hyperglycemia-induced reduction in nephrin expression. Further, knockdown of NOD2 expression attenuated high glucose-induced nephrin downregulation in vitro, supporting an essential role of NOD2 in mediating hyperglycemia-induced podocyte dysfunction. Thus, NOD2 is one of the critical components of a signal transduction pathway that links renal injury to inflammation and podocyte insulin resistance in diabetic nephropathy.

Association of ELMO1 gene polymorphisms with diabetic nephropathy in Chinese population.

Genetic variations in the engulfment and cell motility 1 (ELMO1) gene have recently been identified to be associated with nephropathy attributed to Type 2 diabetes mellitus (T2DM). Since T2DM-associated complications are proved to be more common among Asians than Western individuals, and Chinese people have a high incidence of diabetic nephropathy (DN), this study sought to analyze the association of ELMO1 gene polymorphisms with DN to probe into the effects of ELMO1 gene on susceptibility of DN in Chinese population. We genotyped 6 polymorphism sites of ELMO1 gene in 200 unrelated Chinese subjects (123 T2DM with DN case subjects and 77 T2DM without DN control subjects). Genotyping was detected by a Sequenom MassARRAY genotyping system. The strongest associations in ELMO1 gene with DN occurred at rs741301 [odds ratio (OR) 1.89; p=0.004] and rs10951509 (OR 1.76; p=0.02). Unconditional logistic regression analysis identified that the rs741301 polymorphism (presence of A allele, adjusted OR 3.27; p=0.03) and duration of T2DM (adjusted OR 1.15; p=0.04) were independent predictors for DN. The marker rs741301 located in intron 18 of ELMO1 gene was in strong linkage disequilibrium (LD) with rs11769038 (D'=0.91). Furthermore, haplotype analysis identified that haplotype 1 [CAAAGA] (OR 1.95; p=0.01), haplotype 2 [CAAAGG] (OR 0.50; p=0.01), and haplotype 9 [TGCGGG] (OR 0.17; p=0.007) of ELMO1 were significantly associated with DN. This study first investigated the association of ELMO1 gene polymorphisms with DN in a Chinese population, supporting its key role as a candidate gene in the susceptibility of DN.

IGF2BP2 and IGF2 genetic effects in diabetes and diabetic nephropathy

ObjectiveThe IGF2BP2 gene is located on chromosome 3q27.2 within a region linked to type 1 diabetes (T1D), type 2 diabetes (T2D) and diabetic nephropathy (DN). Its protein functionally binds to 5’-UTR of the imprinting IGF2 gene. The present study aims to evaluate the IGF2BP2-IGF2 genetic effects in diabetes and DN. Materials and MethodsThree cohorts including T1D with and without DN (n=1139) of European descents from the GoKinD study, Swedish T1D with and without DN (n=303) and Czech control subjects without diabetes, T1D, T2D with and without DN (n=1418) were enrolled in TaqMan genotyping experiments for IGF2BP2 rs4402960 and IGF2 rs10770125. Igf2bp2 gene expression in kidney tissues of db/db and control mice at the ages of 5 and 26weeks was examined with real time RT-PCR and Western blot. ResultsAn association of IGF2BP2 rs4402960 with T2D in the Czech population was replicated. This IGF2BP2 polymorphism (P=0.037, OR=0.69 95% CI 0.49–0.98) was found to be associated with DN in male not in female patients with T1D selected from the GoKinD study. In the analyses of combined the GoKinD, Czech and Swedish populations, the association between IGF2BP2 polymorphism and DN in male patients with T1D was still significant (P=0.030, OR=0.73, 95% CI 0.54–0.97). IGF2 rs10770125 was also associated with DN in male T1D patients of the GoKinD population (P=0.038, OR=0.67 95% CI 0.46–0.98). There might be a genetic interaction between IGF2BP2 and IGF2 (P=0.05). The Igf2bp2 gene expression levels were increased in the kidneys of db/db mice compared to controls at the age of 5weeks but not at 26weeks. ConclusionsThe present study has replicated the association of IGF2BP2 rs4402960 with T2D in the Czech population and provided data suggesting that IGF2BP2 may have genetic interaction with IGF2 with a protective effect against DN in male patients with T1D.

Adipocytokine zinc α2 glycoprotein (ZAG) as a novel urinary biomarker for normo‐albuminuric diabetic nephropathy

A substantial proportion of diabetic nephropathy individuals are non-albuminuric. Using a proteomic approach, we searched for novel urinary biomarkers. We studied three groups (n = 6 per group) of males with Type 2 diabetes: (1) normal renal function; (2) classical diabetic nephropathy (urinary albumin-creatinine ratio > 1000 mg/g and glomerular filtration rate < 60 ml/min.1.73 m(2) ) and (3) non-albuminuric diabetic nephropathy (glomerular filtration rate < 60 ml/min.1.73 m(2) and urinary albumin-creatinine ratio < 30 mg/g). We used two-dimensional fluorescence differential gel electrophoresis, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry peptide identification and western blot validation in the study. Sixty protein spots were differentially abundant between the non-albuminuric and macro-albuminuric subjects (> 2.5-fold, P < 0.05). In the non-albuminuric subjects, in addition to previously reported α(1) -microglobulin, the next most interesting spot (upregulated 3.44-fold, P = 0.0026) was human zinc-α(2) -glycoprotein, a novel adipose-cytokine associated with glomerular injury. This was confirmed by western blot and replicated in female diabetic nephropathy subjects. From our preliminary results, human zinc-α(2) -glycoprotein may be a novel urinary biomarker for non-albuminuric diabetic nephropathy.

Genome‐Wide Association of BMI in African Americans

Recent genome-wide association studies (GWAS) have identified multiple novel loci associated with obesity in Europeans but results in other ethnicities are less convincing. Here, we report a two-stage GWAS of BMI in African Americans. The GWAS was performed using the Affymetrix 6.0 platform in 816 nondiabetic and 899 diabetic nephropathy subjects. 746,626 single-nucleotide polymorphisms (SNPs) were tested for association with BMI after adjustment for age, gender, disease status, and population structure. Sixty high scoring SNPs that showed nominal association in both GWAS cohorts were further replicated in 3,274 additional subjects in four replication cohorts and a meta-analysis was computed. Meta-analysis of 4,989 subjects revealed five SNPs (rs6794092, rs268972, rs2033195, rs815611, and rs6088887) at four loci showing consistent associations in both GWAS (P < 0.0001) and replication cohorts (P < 0.05) with combined P values range from 2.4 × 10(-6) to 5 × 10(-5). These loci are located near PP13439-TMEM212, CDH12, MFAP3-GALNT10, and FER1L4 and had effect sizes between 0.091 and 0.167 s.d. unit (or 0.67-1.24 kg/m(2)) of BMI for each copy of the effect allele. Our findings suggest the presence of novel loci potentially associated with adiposity in African Americans. Further replication and meta-analysis in African Americans and other populations will shed light on the role of these loci in different ethnic populations.

Polymorphisms in the Vitamin D Receptor Gene and Parathyroid Hormone Gene in the Development and Progression of Diabetes Mellitus and its Chronic Complications, Diabetic Nephropathy and Non-Diabetic Renal Disease

Background: We chose to study polymorphisms of vitamin D receptor gene (VDR) and parathyroid hormone genes (PTH), whose protein products significantly affect calciumphosphate metabolism in kidneys and are implicated in the pathogenesis of diabetes, which may also involve kidney damage. Methods: Distribution of genotypes of four polymorphisms in VDR gene i.e TaqI (rs731236), BsmI (rs1544410) ApaI (rs7975232), FokI (rs2228570) and two polymorphisms of PTH gene, i.e. DraII (rs6256), BstBI (rs6264), were studied using PCRRFLP. Examined groups consisted of 147 patients with diabetes (DM), 47 patients with nondiabetic renal disease (NDRD), 132 patients with diabetic nephropathy (DN) and 118 healthy subjects. Conclusion: Comparison of DN group and healthy subjects identified statistically significant difference for the FokI polymorphism in VDR gene (P<10-4) and also for the BstBI polymorphism in PTH gene (P=0,023). Differences in DraII polymorphism distribution in PTH gene were statistically significant in each group of patients compared to healthy subjects. In DN patients, the BBFFAATt combination of VDR gene was more frequent than in healthy subjects (P=0,046), and the BbFFAaTt variant was more frequent than in DM2 patients (P=0,018). The BBDD haplotype of PTH gene seems to be a predisposing factor for diabetes itself (P=0,019).

A method for isolation and identification of urinary biomarkers in patients with diabetic nephropathy

The poor performance of current tests for predicting the onset, progression and treatment response of diabetic nephropathy has engendered a search for more sensitive and specific urinary biomarkers. Our goal was to develop a new method for protein biomarker discovery in urine from these patients. We analyzed urine from normal subjects and patients with early and advanced nephropathy. Proteins were separated using a novel analysis process including immunodepletion of high-abundance proteins followed by two-stage LC fractionation of low-abundance proteins. The proteins in the fractions were sequenced using MS/MS. Immunodepletion of selected high-abundance proteins followed by two-stage LC produced approximately 700 fractions, each less complex and more amenable to analysis than the mixture and requiring minimal processing for MS identification. Comparison of fractions between normal and diabetic nephropathy subjects revealed several low-abundance proteins that reproducibly distinguished low glomerular filtration rate (GFR) from both high GFR diabetic and normal subjects, including uteroglobin, a protein previously associated with renal scarring. We developed a novel method to identify low-abundance urinary proteins that enables the discovery of potential biomarkers to improve the diagnosis and management of patients with diabetic nephropathy.

Phospholipidomic identification of potential plasma biomarkers associated with type 2 diabetes mellitus and diabetic nephropathy

Type 2 diabetes mellitus (T2DM) and its attendant complications, such as diabetic nephropathy (DN), impose a significant societal and economic burden. The investigation of discovering potential biomarkers for T2DM and DN will facilitate the prediction and prevention of diabetes. Phospholipids (PLs) and their metabolisms are closely allied to nosogenesis and aggravation of T2DM and DN. The aim of this study is to characterize the human plasma phospholipids in T2DM and DN to identify potential biomarkers of T2DM and DN. Normal phase liquid chromatography coupled with time of flight mass spectrometry (NPLC–TOF/MS) was applied to the plasma phospholipids metabolic profiling of T2DM and DN. The plasma samples from control (n=30), T2DM subjects (n=30), and DN subjects (n=52) were collected and analyzed. The significant difference in metabolic profiling was observed between healthy control group and DM group as well as between control group and DN group by the help of partial least squares discriminant analysis (PLS-DA). PLS-DA and one-way analysis of variance (ANOVA) were successfully used to screen out potential biomarkers from complex mass spectrometry data. The identification of molecular components of potential biomarkers was performed on Ion trap-MS/MS. An external standard method was applied to quantitative analysis of potential biomarkers. As a result, 18 compounds in 7 PL classes with significant regulation in patients compared with healthy controls were regarded as potential biomarkers for T2DM or DN. Among them, 3 DM-specific biomarkers, 8 DN-specific biomarkers and 7 common biomarkers to DM and DN were identified. Ultimately, 2 novel biomarkers, i.e., PI C18:0/22:6 and SM dC18:0/20:2, can be used to discriminate healthy individuals, T2DM cases and DN cases from each other group.

Genetic variation in the matrix metalloproteinase genes and diabetic nephropathy in type 1 diabetes

Genetic data support the notion that polymorphisms in members of the matrix metalloproteinase (MMP) family of genes play an important role in extracellular matrix remodeling and contribute to the pathogenesis of vascular disease. To identify novel genetic markers for diabetic nephropathy (DN), we examined the relationship between MMP gene polymorphisms and DN in the Genetics of Kidneys in Diabetes (GoKinD) population. Genotypic data from the Genetic Association Information Network (GAIN) type 1 DN project were analyzed for associations across 21 MMP genes in 1705 individual with type 1 diabetes, including 885 normoalbuminuric control subjects and 820 advanced DN case subjects. In total, we investigated the role of 1283 SNPs (198 genotyped SNPs and 1085 imputed SNPs) mapping to the MMP genes. We identified associations at several correlated SNPs across a 29.2 kb interval on chromosome 11q at the MMP-3/ MMP-12 locus. The strongest associations occurred at 2 highly-correlated SNPs, rs610950 (OR = 0.50, P = 1.6 × 10 −5) and rs1277718 (OR = 0.50, P = 2.1 × 10 −5). Further examination of this locus identified 17 SNPs (2 genotyped SNPs and 15 imputed SNPs) in complete linkage disequilibrium associated with DN ( P-values < 2.5 × 10 −4), including a non-synonymous SNP (rs652438, Asn357Ser) located in exon 8 of MMP-12 that significantly reduced the risk of DN among carriers of the serine substitution relative to homozygous carriers of asparagine (OR = 0.51; 95% CI = 0.37–0.71, P = 6.2 × 10 −5). Taken together, our study suggests that genetic variations within the MMP-3/ MMP-12 locus influence susceptibility of DN in type 1 diabetes.

Association of the PPARGC1A Gene Polymorphism With Diabetic Nephropathy in an Asian Indian Population (CURES-41)

The aim of this study was to evaluate the association of polymorphisms of the peroxisome proliferator-activated receptor gamma (PPARG) gene and peroxisome proliferators-activated receptor gamma co-activator 1 alpha (PPARGC1A) gene with diabetic nephropathy (DN) in Asian Indians. Six common polymorphisms, 3 of the PPARG gene [-1279G/A, Pro12Ala, and His478His (C/T)] and 3 of the PPARGC1A gene (Thr394Thr, Gly482Ser, and +A2962G) were studied in 571 normal glucose-tolerant (NGT) subjects, 255 type 2 diabetic (T2D) subjects without nephropathy, and 141 DN subjects. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequencing. Logistic regression analysis was performed to assess the covariables associated with DN. Among the 6 polymorphisms examined, only the Gly482Ser of the PPARGC1A gene was significantly associated with DN. The genotype frequency of Ser/Ser genotype of the PPARGC1A gene was 8.8% (50/571) in NGT subjects, 7.8% (20/255) in T2D subjects, and 29.8% (42/141) in DN subjects. The odds ratios (ORs) for DN for the susceptible Gly/Ser and Ser/Ser genotype after adjusting for age, sex, body mass index, and duration of diabetes were 2.14 [95% confidence interval (CI), 1.23-3.72; P = 0.007] and 8.01 (95% CI, 3.89-16.47; P < 0.001), respectively. The unadjusted OR for DN for the XA genotype of the Thr394Thr polymorphism was 1.87 (95% CI, 1.20-2.92; P = 0.006) compared to T2D subjects. However, the significance was lost (P = 0.061) when adjusted for age, sex, BMI, and duration of diabetes. The +A2962G of PPARGC1A and the 3 polymorphisms of PPARG were not associated with DN. The Gly482Ser polymorphism of the PPARGC1A gene is associated with DN in Asian Indians.

Association and interaction analyses of genetic variants in ADIPOQ, ENPP1, GHSR, PPAR and TCF7L2 genes for diabetic nephropathy in a Taiwanese population with type 2 diabetes

Diabetic nephropathy (DN) is a common microvascular complication of diabetes. In this study, we aimed to explore both primary effects of single-locus and multilocus interactions to test the hypothesis that the type 2 diabetes (T2D) genes may contribute to the aetiology of DN in T2D independently and/or through complex interactions in a Taiwanese population with T2D. We genotyped six single nucleotide polymorphisms (SNPs) for five common T2D genes including adiponectin, C1Q and collagen domain containing (ADIPOQ), ectonucleotide pyrophosphatase/ phosphodiesterase 1 (ENPP1), growth hormone secretagogue receptor (GHSR), peroxisome proliferator-activated receptor gamma (PPARgamma) and transcription factor 7-like 2 (TCF7L2). There were 216 T2D patients diagnosed with DN and 178 age-similar T2D without DN (control) subjects. To investigate gene-gene interactions, we employed both generalized multifactor dimensionality reduction (GMDR) method and logistic regression models. Single-locus analyses showed significant main effects of ENPP1 (P = 0.0032; adjusted OR = 1.85; 95% CI = 1.17-2.92) on the risk of DN in T2D. Furthermore, a potential gene-gene interaction involving ENPP1 and GHSR was suggested in the best two-locus GMDR model (P = 0.021). The significant three-locus GMDR model (P < 0.001) was also identified among ADIPOQ, GHSR and TCF7L2. Analyses using logistic regression models confirmed the gene-gene interactions. The results suggest that the SNPs from the T2D-related genes may contribute to the risk of DN in T2D independently and/or in an interactive manner in Taiwanese T2D patients.

Urinary Fatty Acids and Liver-Type Fatty Acid Binding Protein in Diabetic Nephropathy

Background: The aims of this clinical study were to investigate the associations of urinary free fatty acid (FFA) levels with tubulointerstitial damage, and to determine the clinical significance of urinary liver-type fatty acid binding protein (L-FABP) in diabetic nephropathy. Methods: Fifteen patients with nephrotic syndrome due to diabetic nephropathy and 12 patients with minimal-change nephrotic syndrome (MCNS) were studied. Urinary and serum FFA concentrations (palmitic, oleic, linoleic, and arachidonic acids) were measured by gas chromatography, and urinary L-FABP levels were quantified using an ELISA technique. Tubulointerstitial damage was assessed using renal biopsy specimens. Results: The levels of urinary linoleic and arachidonic acids were significantly elevated in diabetic nephropathy compared to MCNS patients, though serum FFA levels were lower in diabetic nephropathy than MCNS patients. The degree of tubulointerstitial damage was significantly severer in the patients with diabetic nephropathy than MCNS. Urinary L-FABP and 8-OHdG (8-hydroxydeoxyguanosine) concentrations were significantly higher in the diabetic nephropathy subjects. Conclusion: Elevated urinary excretion of FFA may be a reflection of FFA overload in the proximal tubules, and FFA may be an important promoter of tubulointerstitial damage in diabetic nephropathy patients. Urinary L-FABP levels may reflect the stress induced by FFA to the proximal tubules, leading to severe tubulointerstitial damage.

Proteinuria-Lowering Effect of Heparin Therapy in Diabetic Nephropathy without Affecting the Renin-Angiotensin-Aldosterone System

Angiotensin-converting enzyme inhibitors and angiotensin II (AngII) type 1 receptor blockers lower proteinuria and preserve renal function in diabetic nephropathy (DN). The antiproteinuric effects are greater than their blood pressure reduction, involving the sieving properties of the glomerular filter. In DN, glomerular staining for heparan sulfate proteoglycans is decreased. AngII inhibits heparan sulfate synthesis. Also, heparins modulate AngII signaling in glomerular cells, inhibiting aldosterone synthesis and lowering proteinuria in DN. Is the antiproteinuric effect of heparins due to its interference with the renin-angiotensin-aldosterone system? Ten volunteers each with DN and glomerulonephritis and control subjects were examined before and after low-dosage enoxaparin. Renal hemodynamics were determined with (99m)Tc-DTPA and (131)I-hippurate clearance. Glomerular filtration rate (GFR), effective renal plasma flow, mean arterial pressure, and heart rate were measured at baseline and during AngII infusion before and after enoxaparin while on normal salt and salt restriction. Enoxaparin did not lower aldosterone levels. GFR remained stable in all groups. AngII caused a significant decrease in effective renal plasma flow, whereas mean arterial pressure and heart rate increased significantly. Enoxaparin did not influence the AngII-induced changes of renal hemodynamics during normal salt intake or salt restriction. All groups showed identical responses to AngII before and after enoxaparin. In patients with diabetes, enoxaparin caused a significant decrease in proteinuria. It is concluded that the antiproteinuric effect of heparins in DN cannot be explained via interaction with the renin-angiotensin-aldosterone system. The absence of hemodynamic changes combined with reduced proteinuria point to intrinsic alterations in the glomerular filter. The effects were seen only in DN, not in glomerulonephritis.