Clinical Diabetic Nephropathy Research Articles

Thiosulfate sulfurtransferase prevents hyperglycemic damage to the zebrafish pronephros in an experimental model for diabetes

Thiosulfate sulfurtransferase (TST, EC 2.8.1.1), also known as Rhodanese, was initially discovered as a cyanide detoxification enzyme. However, it was recently also found to be a genetic predictor of resistance to obesity-related type 2 diabetes. Diabetes type 2 is characterized by progressive loss of adequate β-cell insulin secretion and onset of insulin resistance with increased insulin demand, which contributes to the development of hyperglycemia. Diabetic complications have been replicated in adult hyperglycemic zebrafish, including retinopathy, nephropathy, impaired wound healing, metabolic memory, and sensory axonal degeneration. Pancreatic and duodenal homeobox 1 (Pdx1) is a key component in pancreas development and mature beta cell function and survival. Pdx1 knockdown or knockout in zebrafish induces hyperglycemia and is accompanied by organ alterations similar to clinical diabetic retinopathy and diabetic nephropathy. Here we show that pdx1-knockdown zebrafish embryos and larvae survived after incubation with thiosulfate and no obvious morphological alterations were observed. Importantly, incubation with hTST and thiosulfate rescued the hyperglycemic phenotype in pdx1-knockdown zebrafish pronephros. Activation of the mitochondrial TST pathway might be a promising option for therapeutic intervention in diabetes and its organ complications.

Correlation between serum ferritin and proteinuria as marker of diabetic nephropathy stage in type 2 diabetic patients

Background: Increased iron reserves in the body have been linked to the development of type 2 diabetes, as well as diabetic nephropathy, retinopathy and vascular dysfunction. Serum ferritin has been related to the occurrence of CKD. Aim of study: Aiming to look into the link between serum ferritin and proteinuria as a diabetic nephropathy marker in type 2 diabetic patients. subjects and methods: It involved 50 individuals of the same age and gender who were split into two groups: 25 type 2 diabetic patients with proteinuria and 25 apparently healthy volunteers (hospital personnel) with no history of diabetes who served as the control group. The Enzyme-linked immunosorbent assay (ELIZA) kit for quantitative detection of human serum ferritin was used to estimate serum ferritin. Results: In the current study, serum ferritin levels in diabetics with proteinuria showed a high significant rise when compared to the control group. (p < 0.001). The comparative present study, the mean ± SD of diabetic patients with nephropathy, serum ferritin was 513.91±260.06 than that of control 133.42±186.66. The current study found a high significant positive relationship between ferritin and 24h protein in diabetic patients with nephropathy(r=0.512, p=0.009), show no significant positive association in control group (r=0.02, p=0.94). Conclusion: serum ferritin can be considered as an independent predicting marker of diabetic nephropathy as well as an excellent diagnostic marker for patients with clinical diabetic nephropathy.

Value Analysis of the Combined Detection of Cystatin C, Hypersensitive C-reactive protein and Urinary Microalbumin in the Diagnosis of Early Renal Damage in Diabetes

To explore the value of combined detection of cystatin C, high sensitivity C-reactive protein and microalbuminuria in the diagnosis of early diabetic renal damage. From September 2016 to May 2018, 96 patients with type 2 diabetes were selected and divided into three groups according to the staging criteria of renal damage caused by diabetes: simple diabetes group (32 cases), early diabetic nephropathy group (32 cases) and clinical diabetic nephropathy group (32 cases). Another 32 healthy people in the same period were selected as the control group. Fasting venous blood and urine were collected to detect microalbuminuria, urine microalbuminuria, serum cystatin C and hypersensitive C-reactive protein. The sensitivity and specificity of three detection indexes were analyzed by receiver operating characteristic curve. Compared with the control group, the levels of cystatin C, high sensitivity C-reactive protein and microalbuminuria in the simple diabetic group, the early diabetic nephropathy group and the clinical diabetic nephropathy group were significantly increased (p<0.05); the levels of cystatin C, high sensitivity C-reactive protein and microalbuminuria in the early diabetic nephropathy group and the clinical diabetic nephropathy group were significantly higher than those in the simple diabetic group (p<0.05).In the early diabetes group, the positive rates of cystatin C, high sensitivity C-reactive protein and microalbuminuria were lower than those of combined detection, and the difference was statistically significant (p<0.05). Receiver operating characteristic curve analysis showed that the Area under the curve of microalbuminuria, whole blood high sensitivity C-reactive protein, serum cystatin C and diagnosis of early diabetic nephropathy were 0.960, 0.934 and 0.929 respectively, with high accuracy. The AUC of combined detection of the three indicators was 0.994, with sensitivity and specificity of 100.00 % and 99.70 %. The combined detection of high sensitivity C-reactive protein, microalbuminuria and serum cystatin C can improve the sensitivity and specificity of diagnosis of early diabetic nephropathy, which is of great significance for clinical prevention and treatment of early diabetic nephropathy and progression to end-stage renal disease.

Pyruvate-Enriched Oral Rehydration Solution Improves Glucometabolic Disorders in the Kidneys of Diabetic db/db Mice.

Diabetes is prevalent worldwide, but ideally intensive therapeutic strategy in clinical diabetes and diabetic nephropathy (DN) is still lack. Pyruvate is protective from glucometabolic disturbances and kidney dysfunction in various pathogenic insults. Present studies focused on oral pyruvate effects on diabetes status and DN with 0.35% pyruvate in pyruvate-enriched oral rehydration solution (Pyr-ORS) and 1% pyruvate as drinking water for 8 weeks, using the model of diabetic db/db mice. Both Pyr-ORS and 1% pyruvate showed comparable therapeutic effectiveness with controls of body weight and blood sugar, increases of blood insulin levels, and improvement of renal function and pathological changes. Aberrant key enzyme activities in glucometabolic pathways, AR, PK, and PDK/PDH, were also restored; indexes of oxidative stress and inflammation, NAD+/NADH ratio, and AGEs in the kidneys were mostly significantly preserved after pyruvate treatments. We concluded that oral pyruvate delayed DN progression in db/db mice and the modified Pyr-ORS formula might be an ideal novel therapeutic drink in clinical prevention and treatment of type 2 diabetes and DN.

Glycogen synthase kinase 3β hyperactivity in urinary exfoliated cells predicts progression of diabetic kidney disease

Burgeoning evidence points to glycogen synthase kinase (GSK)3β as a key player in diverse kidney diseases. However, as a pivotal transducer of the insulin signaling pathway, the role of GSK3β in diabetic kidney disease remains uncertain. In db/db mice, renal expression of total and activated GSK3β was increasingly elevated. This preceded the development of diabetic kidney disease, and correlated with the progression of signs of diabetic kidney injury, including albuminuria and extracellular matrix accumulation in glomeruli and tubulointerstitia. Invitro, exposure of glomerular podocytes, mesangial cells, and renal tubular cells to a diabetic milieu induced GSK3β overexpression and hyperactivity, which seem essential and sufficient for eliciting diabetic cellular damages in kidney cells, because the cytopathic effect of the diabetic milieu was mitigated by GSK3β knockdown, but was mimicked by ectopic expression of constitutively active GSK3β even in the normal milieu. In consistency, kidney biopsy specimens procured from patients with varying stages of diabetic nephropathy revealed an amplified expression of total and activated GSK3β in glomeruli and renal tubules, associated with the severity of diabetic nephropathy. Moreover, in retrospective cohorts of type 2 diabetic patients that were followed for over five years, the relative activity of GSK3β in banked urinary exfoliated cells represented an independent risk factor for development or progression of renal impairment. Furthermore, receiver operating characteristic curve analysis demonstrated that GSK3β activity in urinary exfoliated cells provided much better power than albuminuria in discriminating diabetic patients with progressive renal impairment from those with stable kidney function. Thus, renal expression and activity of GSK3β are amplified in experimental and clinical diabetic nephropathy. Hence, GSK3β in urinary exfoliated cells may serve as a novel biomarker for predicting diabetic kidney disease progression.

A Meta-Analysis of the Treatment of Diabetic Nephropathy using Astragalus Injection combined with Captopril

To observe the effectiveness and safety of using astragalus injection combined with captopril for diabetic nephropathy. The method is using computer database searches and manual retrieval of relevant journals. Astragalus injection combined with captopril was the test drug group. The data was analyzed using Review Manager 5.1 according to the evaluation criteria of RCT recommended by Cochrane 4.2.2. 11RCT and total 641 cases of early and clinical diabetic nephropathy were included. Astragalus injection combined with captopril was more excellent than the control group in the lower of 24hUAER [MD=-21.09, (-37.21,-4.96), P<0.01], 24h urinary protein [MD =- 0.38, (- 47, -0.28), P <0.01], the efficient [RR=1.29, (1.06,1.57), P=0.01], BUN [MD=-0.36, (-0.62,-0.11), P=0.004], SCr [MD=-4.13, (-7.94,-0.33), P=0.03], FPG [MD=-0.96, (-1.67,-0.24), P=0.009], TC [MD=-1.42, (-1.66,-1.18), P<0.01], and TG [MD=-0.45, (-0.59,-0.32), P<0.01]. There was no significance in 2h PG [MD=-0.07, (-0.65,0.51), P=0.81], and blood pressure (2 =0.15, P=0.69).. Astragalus injection combined with captopril was effect and safe in the lower of 24hUAER and the efficient for the patients with diabetic nephropathy. It also needs more randomized controlled trials for high-quality evaluation.

EVALUATION OF INTRARENAL RESISTIVE INDEX BY DUPLEX COLOR DOPPLER ULTRASONOGRAPHY IN PATIENTS WITH DIABETIC NEPHROPATHY – COMPARISON BETWEEN HEALTHY ADULT CONTROL SUBJECTS

Background: Renal Doppler Ultrasonography (USG) has become a useful adjunct to gray scale sonography in the evaluation of renal function in various pathophysiological conditions like diabetic nephropathy. We can diagnose diabetic nephropathy by serum creatinine level and creatinine clearance rate. But early stage diagnosis of diabetic nephropathy is not always possible. In this study we have focused on resistive index of interlobar arteries of kidney to see changes of renal parenchyma for early stage diagnosis of diabetic nephropathy.&#x0D; Objectives: To observe the difference between values of intrarenal resistive index measured by duplex color Doppler USG in type 2 diabetic patients having diabetic nephropathy and in healthy adult control subjects.&#x0D; Materials and methods: This cross sectional observational study was conducted in the Department of Radiology and Imaging, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh. 65 diabetic nephropathy patients were taken as study group and 65 healthy subjects were included as healthy control subjects. Duplex Color Doppler Ultrasonography of interlobar artery was carried out in both groups to measure the peak systolic velocity, the end diastolic velocity and arterial Resistive Index.&#x0D; Results: The Resistive Index of interlobar artery of left kidney in control group was 0.58±0.08 and the mean RI of interlobar artery of left kidney in diabetic nephropathy patients was 0.74±0.53. The difference of Resistive index of interlobar artery of left kidney in the two groups were statistically significant and the RI of right kidney of control &amp; that of case groups were 0.60±0.09 and 0.76±0.03 respectively. In between control and case groups the RI of right kidney were statistically significant. So, resistive index of interlobar artery was increased in type 2 diabetic nrphropathy patients compared to control group.&#x0D; Conclusion: It can be concluded in present study that resistive index remains significantly higher in patients with diabetic nephropathy than in controls. Thus Duplex Doppler ultrasonography allows the rapid, noninvasive evaluation of the intrarenal vasculature and can be used as an easily available parameter of the evolution and a predictor in patients with clinical diabetic nephropathy.&#x0D; Keywords: Doppler Ultrasonography, Intrarenal Resistive Index, Diabetic Nephropathy

Study on the relationship between the methylation of the MMP-9 gene promoter region and diabetic nephropathy.

This study aims to explore the relationship between the methylation of matrix metalloproteinase (MMP)-9 gene promoter region and diabetic nephropathy (DN) through the detection of the methylation level of MMP-9 gene promoter region in the peripheral blood of patients with DN in different periods and serum MMP-9 concentration. The methylation level of the MMP-9 gene promoter region was detected by methylation-specific polymerase chain reaction (MSP), and the content of MMP-9 in serum was determined by enzyme-linked immunosorbent assay (ELISA). Results of the statistical analysis revealed that serum MMP-9 protein expression levels gradually increased in patients in the simple diabetic group, early diabetic nephropathy group and clinical diabetic nephropathy group, compared with the control group; and the difference was statistically significant (P < 0.05). Compared with the control group, the methylation levels of MMP-9 gene promoter regions gradually decreased in patients in the simple diabetic group, early diabetic nephropathy group, and clinical diabetic nephropathy group; and the difference was statistically significant (P < 0.05). Furthermore, correlation analysis results indicated that the demethylation levels of the MMP-9 gene promoter region was positively correlated with serum protein levels, urinary albumin to creatinine ratio (UACR), urea and creatinine; and was negatively correlated with GFR. The demethylation of the MMP-9 gene promoter region may be involved in the occurrence and development of diabetic nephropathy by regulating the expression of MMP-9 protein in serum.

Evaluation of Type of Nephropathy in Patients of Type-2 Diabetes Mellitus

Background of the Study, Aims and Objectives: There are very few studies on histological patterns of diabetic nephropathy in our part of country. The aim of this study was to evaluate the renal involvement in patients with Type-2 diabetes mellitus (T2DM), assess the histopathological changes and establish a clinico-pathological correlation. Subjects, Method and Materials: Thirty two Type 2 DM patients with nephropathy, after screening consecutive hundred(100) Type 2 Diabetics admitted to the Medicine Department were evaluated for renal involvement by kidney biopsy and histopathological study. Statistical analysis was done by student’s t-test, chi-square and linear regression analysis. Results: Thirty two patients (32) with diabetic nephropathy (20 males and 12 females) formed the study group out of hundred (100) consecutive Type-2 diabetes mellitus patients (58 males and 42 females) admitted to Medicine Department of SCB Medical College Hospital, Cuttack. The frequency of occurrence of clinical diabetic nephropathy was 32%. Most of the patients were having duration of DM of 6-10 years (87.5%). Pedal edema was found in 96.87%, hypertension in 87.5% patients respectively. Regression analysis showed that durations of DM and HbA1c were the two significant risk factors (P Histopathologically, diffuse glomerulosclerosis was the most common form of renal abnormality found in 93.75% followed by nodular glomerulosclerosis in 62.50% with overlap in many patients, membranous nephropathy in 12.5% and focal necrotising glomerulonephritis in 6.25% respectively. There was no statistically significant clinicopathological correlation observed between clinical and biochemical parameters in patients harbouring the two predominant histological types of nephropathy i.e. diffuse and nodular glomerulosclerosis with respect to age, sex, duration of diabetes, body mass index, systolic blood pressure, HbA1c, 24 hour urinary protein, creatinine clearance, serum urea, serum creatinine or lipid profile. Conclusion: Durations of diabetes and HbA1c were found to be strongly associated with development of diabetic nephropathy. Diffuse glomerulosclerosis was the most common form of renal abnormality found in 93.75% followed by nodular glomerulosclerosis in 62.50% of patients.

Angiotensin-converting enzyme 2 amplification limited to the circulation does not protect mice from development of diabetic nephropathy

Blockers of the renin-angiotensin system are effective inthe treatment of experimental and clinical diabetic nephropathy. An approach different from blocking the formation or action of angiotensin II (1-8) that could also be effective involves fostering its degradation. Angiotensin-converting enzyme 2 (ACE2) is a monocarboxypeptidase that cleaves angiotensin II (1-8) to form angiotensin (1-7). Therefore, we examined the renal effects of murine recombinant ACE2 in mice with streptozotocin-induced diabetic nephropathy as well as that of amplification of circulating ACE2 using minicircle DNA delivery prior to induction of experimental diabetes. This delivery resulted in a long-term sustained and profound increase in serum ACE2 activity and enhanced ability to metabolize an acute angiotensin II (1-8) load. In mice with streptozotocin-induced diabetes pretreated with minicircle ACE2, ACE2 protein in plasma increased markedly and this was associated with a more than 100-fold increase in serum ACE2 activity. However, minicircle ACE2 did not result in changes in urinary ACE2 activity as compared to untreated diabetic mice. In both diabetic groups, glomerular filtration rate increased significantly and to the same extent ascompared to non-diabetic controls. Albuminuria, glomerular mesangial expansion, glomerular cellularity, and glomerular size were all increased to a similar extent in minicircle ACE2-treated and untreated diabetic mice, as compared to non-diabetic controls. Recombinant mouse ACE2 given for 4 weeks by intraperitoneal daily injections in mice with streptozotocin-induced diabetic nephropathy also failed to improve albuminuria or kidney pathology. Thus, a profound augmentation of ACE2 confined to the circulation failed to ameliorate the glomerular lesions and hyperfiltration characteristic of early diabetic nephropathy. These findings emphasize the importance of targeting thekidney rather than the circulatory renin angiotensin system to combat diabetic nephropathy.

Cardiovascular autonomic neuropathy associates with nephropathy lesions in American Indians with type 2 diabetes

AimsCardiovascular autonomic neuropathy (CAN) predicts clinical diabetic nephropathy (DN). We investigated the relationship between DN structural lesions and CAN. MethodsSixty three Pima Indians with type 2 diabetes underwent kidney biopsies following a 6-year clinical trial testing the renoprotective efficacy of losartan vs. placebo. CAN was assessed a median 9.2years later. CAN variables included expiration/inspiration ratio (E/I), standard deviation of the normal R-R interval (sdNN), and low and high frequency signal power and their ratio (LF, HF, LF/HF); lower values reflect more severe neuropathy. Associations of CAN with renal structural variables were assessed by linear regression adjusted for age, sex, diabetes duration, blood pressure, HbA1c, glomerular filtration rate, and treatment assignment during the trial. ResultsGlobal glomerular sclerosis was negatively associated with sdNN (partial r=−0.35, p=0.01) and LF (r=−0.32, p=0.02); glomerular basement membrane width was negatively associated with all measures of CAN except for LF/HF (r=−0.28 to −0.42, p<0.05); filtration surface density was positively associated with sdNN, LF, and HF (r=0.31 to 0.38, p<0.05); and cortical interstitial fractional volume was negatively associated with HF (r=−0.27, p=0.04). ConclusionsCAN associates with DN lesions.

Serum Levels of Progranulin Are Closely Associated with Microvascular Complication in Type 2 Diabetes.

Objective. Progranulin (PGRN) was recently introduced as a novel marker of chronic inflammatory response in obesity and type 2 diabetes capable of directly affecting the insulin signaling pathway. This study aimed to investigate the correlation between PGRN and type 2 diabetics with microvascular complications. Methods. PGRN serum levels and glucose metabolism related substance were measured in 84 type 2 diabetic patients with or without microangiopathies and 12 health persons. Further analyses of serum PGRN in different stages of diabetic microangiopathies were conducted. Results. Serum levels of PGRN were markedly higher in type 2 diabetic patients with microangiopathies. PGRN serum levels increased with the progress of diabetic microangiopathies with significantly highest values detectable in clinical diabetic nephropathy (CDN) and proliferative diabetic retinopathy (PDR) groups. Serum PGRN concentrations in all individuals positively and markedly correlated with systolic blood pressure (SBP), diastolic blood pressure (DBP), body mass index (BMI), triglyceride (TG), urinary albumin excretion rate (UAER), blood urea nitrogen (BUN), creatinine (CRE), white blood cell (WBC), disease duration, IL-6, and TNF-α, while correlating negatively and significantly with eGFR. Multiple linear regression analysis showed that only UAER and CRE were independently associated with serum PGRN. Conclusion. PGRN might be considered as a marker for diabetic microangiopathy and its severity.

Renal Lesions Predict Progression of Diabetic Nephropathy in Type 1 Diabetes

Whether early glomerular, tubulointerstitial, vascular, and global glomerulosclerotic lesions can predict progression of diabetic nephropathy is not well defined. Here, we sought to determine whether renal structural parameters predict the development of proteinuria or ESRD after long-term follow-up. We measured several renal structures in kidney biopsies from 94 normoalbuminuric patients with longstanding type 1 diabetes using unbiased morphometric methods. Greater width of the glomerular basement membrane and higher levels of glycated hemoglobin were independent predictors of progression to diabetic nephropathy in this normoalbuminuric cohort. Moreover, none of these patients with type 1 diabetes who had glomerular basement membrane widths within the normal range developed proteinuria and/or ESRD. In conclusion, careful quantitative assessment of kidney biopsies in normoalbuminuric patients with type 1 diabetes adds substantially to the prediction of progression to clinical diabetic nephropathy.

平常生活活動時の微量尿蛋白および酵素N-acetyl-β-D-glucosarninidase(NAG)尿中排泄の日内変動

The present investigation was performed to confirm the relationship between the circadian variation of microproteinuria and physical activity. Urine samples from 10 normal male volunteers, collected during six consecutive 4-h periods, were examined for albumin, alpha 1-, beta 2-microglobulin, NAG, electrolytes and hormones. The fluctuations in heart rate (HR) and blood pressure (BP) over 24-h were measured at 30-min and 1-h intervals, respectively. Energy expenditure (EE) was calculated using the equation of regression between HR and oxygen uptake measured on another day. The variations of HR (delta HR) and EE (delta EE) based on a 24-h average (bpm and kcal/kg/h) were used as indices of change in physical activity during an ordinary day. The correlation coefficients between delta HR and the variations of albumin (delta Alb) and beta 2-microglobulin (delta beta 2M) from the 24-h average (micrograms/h.cr 1 mg) were 0.619 and 0.670 (p less than 0.001), respectively. Increased excretions of both glomerular and tubular proteins were correlated with the increase in HR and/or EE during daytime activity. During rest time at night, the variations in alpha 1M, beta 2M and NAG excretion were different from the variations in albumin. A temporary inhibition of tubular protein excretion was observed only in the early morning (04:00-08:00), although albumin excretion was inhibited throughout the nighttime. These findings suggested that physical activity may influence the diurnal variations in protein excretions, that albuminuria may be more sensitive to daytime activity, and that fluctuation of tubular protein excretion may be preferably controlled by an endogenous mechanism. Timed overnight or first-morning urine may be recommendable as a sample for determination of microalbuminuria for screening of clinical diabetic nephropathy.

Rho kinase inhibition protects kidneys from diabetic nephropathy without reducing blood pressure

Rho-associated kinases (ROCK) are activated in the kidney as well as in cultured cells of diabetic models and have been implicated in renal pathophysiology. To explore whether inhibition of ROCK is protective, we studied its role in a model of accelerated diabetic nephropathy where uninephrectomized rats were made diabetic by streptozotocin. After establishing diabetes, rats were treated with the ROCK inhibitor fasudil continuously or for the final 6 weeks of an 18-week experimental period. The results were compared to similar rats given losartan, an established treatment of clinical and experimental diabetic nephropathy, or a combination of both agents. Vehicle-treated diabetic and non-diabetic uninephrectomized rats served as controls. Diabetes resulted in a rapid development of albuminuria, higher glomerulosclerosis and interstitial fibrosis scores, lower glomerular filtration rates, and increased expression of several molecular markers of diabetic nephropathy. Eighteen weeks of fasudil treatment reduced renal ROCK activity, and ameliorated diabetes-induced structural changes in the kidney and expression of the molecular markers in association with a modest anti-proteinuric effect but no change in blood pressure. Late intervention with fasudil reduced glomerulosclerosis, but did not influence proteinuria. Most effects of fasudil were comparable to those of losartan, although losartan lowered blood pressure and further lowered proteinuria. The combination of both treatments was no different than losartan alone. Thus, ROCK inhibition protected the kidney from diabetic nephropathy even though it did not reduce the blood pressure.

Increased protein damage in renal glomeruli, retina, nerve, plasma and urine and its prevention by thiamine and benfotiamine therapy in a rat model of diabetes

The aim of this study was to quantify protein damage by glycation, oxidation and nitration in a rat model of diabetes at the sites of development of microvascular complications, including the effects of thiamine and benfotiamine therapy. Diabetes was induced in male Sprague-Dawley rats by 55 mg/kg streptozotocin and moderated by insulin (2 U twice daily). Diabetic and control rats were given thiamine or benfotiamine (7 or 70 mg kg(-1) day(-1)) over 24 weeks. Plasma, urine and tissues were collected and analysed for protein damage by stable isotopic dilution analysis MS. There were two- to fourfold increases in fructosyl-lysine and AGE content of glomerular, retinal, sciatic nerve and plasma protein in diabetes. Increases in AGEs were reversed by thiamine and benfotiamine therapy but increases in fructosyl-lysine were not. Methionine sulfoxide content of plasma protein and 3-nitrotyrosine content of sciatic nerve protein were increased in diabetes. Plasma glycation free adducts were increased up to twofold in diabetes; the increases were reversed by thiamine. Urinary excretion of glycation, oxidation and nitration free adducts was increased by seven- to 27-fold in diabetes. These increases were reversed by thiamine and benfotiamine therapy. AGEs, particularly arginine-derived hydroimidazolones, accumulate at sites of microvascular complication development and have markedly increased urinary excretion rates in experimental diabetes. Thiamine and benfotiamine supplementation prevented tissue accumulation and increased urinary excretion of protein glycation, oxidation and nitration adducts. Similar effects may contribute to the reversal of early-stage clinical diabetic nephropathy by thiamine.

Spontaneous glomerular deposition of immunoglobulins for ACE (Angiotensin Converting Enzyme) induces spontaneous nephropathy in diabetogenic rats

AbstractWe first discovered autoantibodies to ACE (angiotensin converting enzyme) in patients with type 2 diabetes mellitus^1^. The antibodies were positive for 64.5% of the patients with diabetes and were positive in 83.3% in the early stage of clinical diabetic nephropathy. In addition, in genetically diabetogenic OLETF (Otsuka Long-Evans Tokushima Fatty) rats^2^, one of the characteristics of which strain is spontaneous nephropathy resembling those of human type 2 diabetes, and in control LETO rats^2^, immunization with rabbit lung ACE developed glomerulopathy similar to that seen in diabetics^3^. Also, in normal New Zealand white rabbits, immunization with the rabbit lung ACE induced glomerular changes similar to those seen in diabetic nephropathy^3^. In this study, renal tissues identical to those examined in research of diabetic nephropathy by PAS staining and electron microscope in preceding study^3^, were examined by immunostaining methods, only to prove that the diabetic glomerular changes may occur by immunization with ACE, not by non-specific responses to ACE, in non-diabetogenic rats and rabbits.

The MIF Receptor CD74 in Diabetic Podocyte Injury

Although metabolic derangement plays a central role in diabetic nephropathy, a better understanding of secondary mediators of injury may lead to new therapeutic strategies. Expression of macrophage migration inhibitory factor (MIF) is increased in experimental diabetic nephropathy, and increased tubulointerstitial mRNA expression of its receptor, CD74, has been observed in human diabetic nephropathy. Whether CD74 transduces MIF signals in podocytes, however, is unknown. Here, we found glomerular and tubulointerstitial CD74 mRNA expression to be increased in Pima Indians with type 2 diabetes and diabetic nephropathy. Immunohistochemistry confirmed the increased glomerular and tubular expression of CD74 in clinical and experimental diabetic nephropathy and localized glomerular CD74 to podocytes. In cultured human podocytes, CD74 was expressed at the cell surface, was upregulated by high concentrations of glucose and TNF-alpha, and was activated by MIF, leading to phosphorylation of extracellular signal-regulated kinase 1/2 and p38. High glucose also induced CD74 expression in a human proximal tubule cell line (HK2). In addition, MIF induced the expression of the inflammatory mediators TRAIL and monocyte chemoattractant protein 1 in podocytes and HK2 cells in a p38-dependent manner. These data suggest that CD74 acts as a receptor for MIF in podocytes and may play a role in the pathogenesis of diabetic nephropathy.

Application of Liquid Chromatography–Mass Spectrometry Technology for Early Detection of Microalbuminuria in Patients with Kidney Disease

Proteinuria is an early and sensitive marker of renal damage in many forms of chronic kidney disease. In diabetes mellitus, mild albuminuria occurs early in the course of renal damage, and this microalbuminuria, defined as urinary albumin excretion of 30–300 mg/day (∼20–200 μg/min), is the best noninvasive predictor of subsequent clinical diabetic nephropathy. Without proper treatment, early diabetic kidney damage progresses to end-stage kidney failure in 5–7 years. With early detection, however, the onset of kidney disease can be slowed, halted, and in some cases reversed through treatment with drugs such as inhibitors of angiotensin-converting enzyme and blockers of angiotensin-2 receptor, particularly if drug treatments is combined with tight blood sugar control and, possibly, decreased protein intake (1)(2). Therefore, strong interest is directed toward detecting patients at risk of diabetic nephropathy as early as possible (3). Current microalbuminuria assays use various immunochemical methods (4). These assays may lead to underestimation of albuminuria in some patients, possibly contributing to delayed diagnosis of early diabetic nephropathy, as indicated by data generated with a recently developed, FDA-cleared size-exclusion HPLC with ultraviolet detection (SEC-HPLC-UV) method (Accumin™, AusAm Biotechnologies). Urine sample analysis with this assay has yielded consistently higher albumin concentrations than immunoassays (5). In one study, microalbuminuria was detected by SEC-HPLC-UV in 53% of urine samples from diabetic patients that were normalbuminic according to an immunochemical method (6). In another study, the SEC-HPLC-UV method was reported to detect microalbuminuria 1–12 years earlier than widely used commercial tests (7). It has been hypothesized that the higher values obtained with the SEC-HPLC-UV assay are attributable to detection of modified forms of albumin. These redox and glycation modifications of the albumin do not change the size of the albumin markedly, and thus with the SEC-HPLC-UV method they are detected under the same peak as …

Research into the glomerular podocyte—is it relevant to diabetic nephropathy?

The cause of proteinuria in renal disease is the subject of intensive research and, latterly, the podocyte, a specialized epithelial cell of the kidney glomerulus, has been the focus of much of this endeavour. It is a complex cell with functions and structural features that have an important role in the development of proteinuria. This review explores some of the characteristics of the podocyte and how abnormalities of its structure and function may have particular relevance to the development and progression of clinical diabetic nephropathy.