Renal risk and renoprotection among ethnic groups with type 2 diabetic nephropathy: a post hoc analysis of RENAAL

Podocyturia an emerging biomarker for kidney injury

Podocyte injury is an established hallmark of kidney disease progression. Podocyte loss is a widely proven hypothesis to explain, in part, glomerular damage. Regardless of the underlying kidney disease, the pathophysiologic processes frequently involve the glomerulus. A growing body of evidence considered that podocytes detachment (podocytopathy) and their presence in the urine (podocyturia) are the hallmark of glomerular disease progression. As such, developing new tools to monitor disease progression non-invasively is of major clinical importance. Detection of podocytes in the urine as a biomarker of disease progression would be a major achievement toward the development of such tools. This review summarizes current knowledge about podocyturia.

High Fat Diet Induces Kidney Injury via Stimulating Wnt/β-Catenin Signaling

High fat diet could cause kidney injury, and the underlying mechanism remains incompletely understood. In this study, we investigated the role of Wnt signaling in this process. Mice were fed with high-fat diet in vivo, and podocytes were stimulated with palmitate in vitro. In mice fed with high-fat diet, renal function was impaired, accompanied by induction of various proinflammatory cytokines and proteinuria. Renal expression of Wnt ligands was also significantly induced, with Wnt1 and Wnt3a being the most pronounced, in high-fat diet mice, compared with normal diet controls. Intervention with ICG-001, a small molecule Wnt/β-catenin inhibitor, improved renal function, inhibited proinflammatory cytokines expression, reduced proteinuria and alleviated podocyte injury. In palmitate-treated podocytes, intracellular lipid deposition was increased, Wnt1 and Wnt3a expression was up-regulated, which was accompanied by an increased proinflammatory cytokines expression and podocyte injury. These lesions caused by palmitate were largely alleviated by ICG-001. Furthermore, ICG-001 also restored the expression of phosphorylated AMPK repressed by palmitate in podocytes or a high-fat diet in mice. These studies suggest that Wnt/β-catenin signaling is involved in the pathogenesis of high-fat diet-induced kidney injury. Targeting this signaling may be a potential therapeutic strategy for alleviating obesity-related nephropathy.

Proteinuria as a Nascent Predictor of Frailty Among People With Metabolic Syndrome: A Retrospective Observational Study

Frailty is a commonly occurring geriatric condition that increases the risk of adverse health outcomes. The factors and predictors behind frailty are not yet well understood. A better understanding of these factors can enable prevention of frailty in elderly patients. The objective of this study was to determine the association between proteinuria and frailty in US individuals with metabolic syndrome (MetS). Data from the National Health and Nutrition Examination Survey III (NHANES III, 1988–1994) conducted by the National Center for Health Statistics of the Centers for Disease Control and Prevention. This is a cross-sectional study, and proteinuria and frailty were measured only once at enrollment. The study included 2,272 participants with MetS aged 40–90 years from the NHANES III. The participants underwent assessments to evaluate frailty and frailty components (low body weight, weakness, exhaustion, low physical activity, and slow walking). Proteinuria was represented as albumin-to-creatinine ratio (ACR) (mg/g) and divided into tertiles: T1-normal range (ACR <30 mg/g), T2-microalbuminuria (ACR 30–299 mg/g), and T3-macroalbuminuria (ACR ≥ 300 mg/g). We applied multiple logistic regression to determine the odds ratios (ORs) of frailty for T2 vs. T1 and T3 vs. T1 in both sexes. In the adjusted analysis for male participants, the ORs of frailty for T2 and T3 vs. T1 were 3.106 (95% confidence interval [CI] = 1.078–8.948, P = 0.036) and 14.428 (95% CI = 4.231–49.193, P < 0.001), respectively. For female participants, the ORs of frailty for T2 and T3 vs. T1 were 1.811 (95% CI = 1.071–3.063, P = 0.027) and 2.926 (95% CI = 1.202–7.124, P = 0.018), respectively. The positive association between T2 and T3 vs. T1, and frailty were statistically significant. The trends of higher likelihood of every frailty component were also statistically significant across increasing tertiles of proteinuria after multiple levels of adjustment for covariates (P < 0.05). Increased proteinuria levels were positively associated with frailty and each frailty component. Proteinuria might be a useful maker for frailty in individuals with MetS.

Interleukin-33/ Suppression of Tumorigenicity 2 in Renal Fibrosis: Emerging Roles in Prognosis and Treatment

Chronic kidney disease (CKD) is a major public health problem that affects more than 10% of the population worldwide and has a high mortality rate. Therefore, it is necessary to identify novel treatment strategies for CKD. Incidentally, renal fibrosis plays a central role in the progression of CKD to end-stage renal disease (ESRD). The activation of inflammatory pathways leads to the development of renal fibrosis. In fact, interleukin-33 (IL-33), a newly discovered member of the interleukin 1 (IL-1) cytokine family, is a crucial regulator of the inflammatory process. It exerts pro-inflammatory and pro-fibrotic effects via the suppression of tumorigenicity 2 (ST2) receptor, which, in turn, activates other inflammatory pathways. Although the role of this pathway in cardiac, pulmonary, and hepatic fibrotic diseases has been extensively studied, its precise role in renal fibrosis has not yet been completely elucidated. Recent studies have shown that a sustained activation of IL-33/ST2 pathway promotes the development of renal fibrosis. However, with prolonged research in this field, it is expected that the IL-33/ST2 pathway will be used as a diagnostic and prognostic tool for renal diseases. In addition, the IL-33/ST2 pathway seems to be a new target for the future treatment of CKD. Here, we review the mechanisms and potential applications of the IL-33/ST2 pathway in renal fibrosis; such that it can help clinicians and researchers to explore effective treatment options and develop novel medicines for CKD patients.

The Association of Postprandial Triglyceride Variability with Renal Dysfunction and Microalbuminuria in Patients with Type 2 Diabetic Mellitus: A Retrospective and Observational Study

OBJECTIVE

We examined whether or not day-to-day variations in lipid profiles, especially triglyceride (TG) variability, were associated with the exacerbation of diabetic kidney disease.

METHODS

We conducted a retrospective and observational study. First, 527 patients with type 2 diabetes mellitus (DM) who had had their estimated glomerular filtration rate (eGFR) checked every 6 months since 2012 for over 5 years were registered. Variability in postprandial TG was determined using the standard deviation (SD), SD adjusted (Adj-SD) for the number of measurements, and maximum minus minimum difference (MMD) during the first three years of follow-up. The endpoint was a ≥40% decline from baseline in the eGFR, initiation of dialysis or death. Next, 181 patients who had no micro- or macroalbuminuria in February 2013 were selected from among the 527 patients for an analysis. The endpoint was the incidence of microalbuminuria, initiation of dialysis, or death.

RESULTS

Among the 527 participants, 110 reached a ≥40% decline from baseline in the eGFR or death. The renal survival was lower in the higher-SD, higher-Adj-SD, and higher-MMD groups than in the lower-SD, lower-Adj-SD, and lower-MMD groups, respectively (log-rank test p = 0.0073, 0.0059, and 0.0195, respectively). A lower SD, lower Adj-SD, and lower MMD were significantly associated with the renal survival in the adjusted model (hazard ratio, 1.62, 1.66, 1.59; 95% confidence intervals, 1.05-2.53, 1.08-2.58, 1.04-2.47, respectively). Next, among 181 participants, 108 developed microalbuminuria or death. The nonincidence of microalbuminuria was lower in the higher-SD, higher-Adj-SD, and higher-MMD groups than in the lower-SD, lower-Adj-SD, and lower-MMD groups, respectively (log-rank test p = 0.0241, 0.0352, and 0.0474, respectively).

CONCLUSIONS

Postprandial TG variability is a novel risk factor for eGFR decline and the incidence of microalbuminuria in patients with type 2 DM.

Epidemiological characteristics of diabetic kidney disease in Taiwan

Diabetic kidney disease (DKD) is a critical microvascular complication of diabetes. With the continuous increase in the prevalence of diabetes since 2000, the prevalence of DKD has also been increasing in past years. The prevalence of DKD among individuals with type 2 diabetes in Taiwan increased from 13.32% in 2000 to 17.92% in 2014. The cumulative incidence of DKD among individuals with type 1 diabetes in Taiwan was higher than 30% during 1999-2012. DKD is the leading cause of end-stage renal disease (ESRD), with a prevalence of approximately 45% in a population on chronic dialysis in Taiwan. Among individuals with type 2 diabetes, the prevalence of ESRD in the receipt of dialysis also increased from 1.32% in 2005 to 1.47% in 2014. Risk factors for DKD development are age, race, family history, hyperglycemia, hypertension, dyslipidemia, dietary patterns, and lifestyles. Prognostic factors that aggravate DKD progression include age, family history, sex, glycemic control, blood pressure (BP), microvascular complications, and atherosclerosis. This review summarizes updated information on the onset and progression of DKD, particularly in the Taiwanese population. Translating these epidemiological features is essential to optimizing the kidney care and improving the prognosis of DKD in Asian populations.

Delay Early CKD with Lifestyle Intervention in African Americans with Diabetic Kidney Disease (DELAY DKD): A Pre-Post Pilot Study (Preprint)

Background

Behavioral factors, such as lifestyle, have been shown to explain approximately 24% of the excess risk of chronic kidney disease (CKD) among African Americans. However, there are limited intervention studies culturally tailored to African Americans with type 2 diabetes mellitus and CKD.

Objective

The main objective of this study was to examine the feasibility and preliminary efficacy of a culturally tailored lifestyle intervention among African Americans with type 2 diabetes mellitus and CKD.

Methods

A pre-post design was used to test the feasibility of a lifestyle intervention in 30 African American adults recruited from the Medical University of South Carolina between January 2017 and February 2017. A research nurse delivered the manualized study intervention weekly for 6 weeks. Clinical outcomes (hemoglobin A_1c, blood pressure, and estimated glomerular filtration rate [eGFR]) were measured at baseline and postintervention. Disease knowledge, self-care, and behavior outcomes were also measured using validated structured questionnaires at baseline and postintervention. Descriptive statistics and effect sizes were calculated to determine clinically important changes from baseline.

Results

Significant pre-post mean differences and decreases were observed for hemoglobin A_1c (mean 0.75%, 95% CI 0.16-1.34; P=.01), total cholesterol (mean 16.38 mg/dL, 95% CI 5.82-26.94; P=.004), low-density lipoprotein (mean 13.73 mg/dL, 95% CI 3.91-23.54; P=.008), and eGFR (mean 6.73 mL/min/1.73m², 95% CI 0.97-12.48; P=.02). Significant pre-post mean differences and increases were observed for CKD self-efficacy (mean −11.15, 95% CI −21.55 to −0.75; P=.03), CKD knowledge (mean −2.62, 95% CI −3.98 to −1.25; P<.001), exercise behavior (mean −1.21, 95% CI −1.96 to −0.46; P=.003), and blood sugar testing (mean −2.15, 95% CI −3.47 to −0.83; P=.003).

Conclusions

This study provides preliminary data for a large-scale appropriately powered randomized controlled trial to examine a culturally tailored lifestyle intervention in African Americans with type 2 diabetes mellitus and CKD in order to improve clinical, knowledge, self-care, and behavior outcomes in this population.

Soluble ST2 and Galectin-3 as Predictors of Chronic Kidney Disease Progression and Outcomes

BACKGROUND

Soluble suppression of tumorigenicity-2 (sST2) and galectin-3, novel biomarkers of heart failure and cardiovascular stress, predict cardiovascular events (CVEs) and mortality. However, their relationship with kidney function and adverse outcomes in CKD are uncertain. The purpose of this study was to determine the association between sST2 and galectin-3 with CKD progression and adverse clinical outcomes.

METHODS

We measured baseline sST2 and galectin-3 levels in the CKD patient cohort at our institution between October 2013 and December 2014. The primary outcome was CKD progression (kidney failure with replacement therapy or ≥50% reduction in estimated glomerular filtration rate from the baseline). The secondary outcome was the composite of CVEs and death. We used a Cox proportional hazards model to evaluate the associations between sST2 and galectin-3 levels, with kidney and clinical outcomes.

RESULTS

In total, 352 patients were enrolled in this study. At baseline, log sST2 and galectin-3 were directly associated with the serum creatinine (Cr) and urine protein-to-Cr ratio. Cox regression analysis showed that the baseline log sST2 level independently predicted CKD progression and composite outcome after adjustment for age, sex, smoking, diabetes mellitus, hypertension, cardiovascular disease, renin-angiotensin system blocker, calcium channel blocker, β-blocker, diuretics, antiplatelet agents, anemia, and hypoalbuminemia. The baseline log galectin-3 level was independently associated with CKD progression, but not with the composite outcome after adjustment for confounding variables.

CONCLUSIONS

Elevated levels of sST2 and galectin-3 are significantly associated with CKD progression, but only sST2 is associated with adverse clinical outcomes.

Pathogenesis of diabesity-induced kidney disease: role of kidney nutrient sensing

Diabetes kidney disease (DKD) is a major healthcare problem associated with increased risk for developing end-stage kidney disease and high mortality. It is widely accepted that DKD is primarily a glomerular disease. Recent findings however suggest that kidney proximal tubule cells (KPTCs) may play a central role in the pathophysiology of DKD. In diabetes and obesity, KPTCs are exposed to nutrient overload, including glucose, free-fatty acids and amino acids, which dysregulate nutrient and energy sensing by mechanistic target of rapamycin complex 1 and AMP-activated protein kinase, with subsequent induction of tubular injury, inflammation, and fibrosis. Pharmacological treatments that modulate nutrient sensing and signaling in KPTCs, including cannabinoid-1 receptor antagonists and sodium glucose transporter 2 inhibitors, exert robust kidney protective effects. Shedding light on how nutrients are sensed and metabolized in KPTCs and in other kidney domains, and on their effects on signal transduction pathways that mediate kidney injury, is important for understanding the pathophysiology of DKD and for the development of novel therapeutic approaches in DKD and probably also in other forms of kidney disease.

Thiamine Level in Type I and Type II Diabetes Mellitus Patients: A Comparative Study Focusing on Hematological and Biochemical Evaluations

Objective Diabetes has been found to be associated with low levels of thiamine stores in the body, as thiamine directly affects carbohydrate metabolism. Amplified renal clearance of thiamine has been found in both type I and type II diabetic patients. It has been shown that high-dose thiamine therapy may have a therapeutic effect on early-stage diabetic nephropathy. The aim of this study was to evaluate various biochemical parameters and serum thiamine levels in type I and type II diabetic patients and compare them with a healthy control group. Methods A case-control study was carried out in the diabetic out-patient multi-centers in Karachi. A total of 90 participants were selected by using a non-probability convenient sampling technique and divided into three groups, each with 30 subjects. Group A included healthy non-diabetic subjects, while group B included subjects with type I diabetes mellitus (DM), and group C included subjects with type II DM. After receiving informed consent, blood samples were collected from all the participants for hematological and biochemical evaluation. The duration of the study was eight months. Results The study results revealed that the patients with type II DM had significantly higher mean fasting blood sugar (FBS), random blood sugar (RBS), and hemoglobin A1c (HbA1c) levels than those with type I DM or the control group (p<0.001 for all). Furthermore, the patients with type I or II DM had significantly higher mean levels of triglyceride (p<0.001) and total cholesterol (0.013) while significantly lower mean levels of high-density lipoprotein (HDL) (p=0.014) than controls. The study results further revealed that the patients with type I or II DM had significantly lower serum thiamine levels than controls (14.89±4.82 and 7.35±1.90 vs. 69.56±12.75, p<0.001). Conclusion The study results revealed that FBS, RBS, HbA1c, triglyceride, and total cholesterol levels were significantly higher in both type I and type II diabetes patients compared to controls. Furthermore, HDL and serum thiamine levels were found to be significantly lower in both type I and type II diabetic patients than in controls.

COX-2-derived prostaglandins as mediators of the deleterious effects of nicotine in chronic kidney disease

Tobacco smoking has been identified as a risk factor in the progression of chronic kidney disease (CKD). In previous studies, we showed that nicotine induces cyclooxygenase (COX)-2 expression in vivo and in vitro and that the administration of nicotine in vivo worsens the severity of renal injury in a model of subtotal renal ablation. In the present study, we tested the role of COX-2-derived prostaglandins on the deleterious effects of nicotine in CKD. Sham and 5/6 nephrectomy (5/6Nx) rats received tap water or nicotine (100 μg/mL) in the drinking water for 12 wk. Additional groups also systemically received the COX-2 inhibitor NS-398 (1.5 mg·kg^-1·day^-1 via osmotic minipump). The administration of nicotine worsened renal injury and proteinuria in 5/6Nx rats and increased proteinuria in sham rats. 5/6Nx rats had increased cortical production of the prostaglandins PGE₂, PGI₂, PGD₂, and PGF_2α and of thromboxane A₂. In these rats, nicotine reduced the production of all prostaglandins examined except thromboxane A₂. Treatment with the COX-2 inhibitor NS-398 resulted in complete inhibition of all prostaglandins studied and ameliorated renal injury and proteinuria in 5/6Nx rats on nicotine but not in 5/6 Nx rats on tap water. Nicotine also reduced the expression of megalin in all groups examined, and this was partially prevented by COX-2 inhibition. In the present study, we showed that in CKD, nicotine worsens renal injury at least in part by producing an imbalance in the production of prostaglandins. This imbalance in the production of prostaglandins likely plays a role in the deleterious effects of smoking on the progression of CKD.

New Understanding on the Role of Proteinuria in Progression of Chronic Kidney Disease

Proteinuria is identified as an important marker and risk factor of progression in chronic kidney disease. However, the precise mechanism of action in the progress of chronic kidney disease is still unclear. Mesangial toxicity from specific filtered compounds such as albumin-bound fatty acids and transferrin/iron, tubular overload and hyperplasia, and induction of proinflammatory molecules such as MCP-1 and inflammatory cytokines are some of the proposed mechanisms. Reversing intraglomerular hypertension with protein restriction or antihypertensive therapy may be beneficial both by diminishing hemodynamic injury to the glomeruli and by reducing protein filtration. Therefore, understanding proteinuria and its role in renal tubular interstitial inflammation and fibrosis is of great significance for the study of renal protective therapy, such as antiproteinuric treatments, and delaying the progression of chronic renal disease.

The incessant search for renal biomarkers: is it really justified?

PURPOSE OF REVIEW

This review summarizes the most recent and relevant findings in the search for novel biomarkers for the most common renal diseases.

RECENT FINDINGS

Unprecedented, fast-paced technical advances in biomedical research have offered an opportunity to identify novel and more specific renal biomarkers in several clinical settings. However, despite the huge efforts made, the molecules identified so far have generally failed to provide relevant information beyond what has already been generated by established biomarkers, such as serum creatinine and proteinuria, whereas the complexity and costs of these technology platforms hamper their widespread implementation.

SUMMARY

No novel renal biomarkers have added clear-cut additional value in clinical decision-making. The only exception is anti-phospholipase A2 receptor antibodies, which have been implemented successfully as a diagnostic and prognostic biomarker of membranous nephropathy. This achievement, along with the large number of ongoing collaborative projects worldwide, should lead the renal community to be quite confident regarding the successful qualification of novel and effective diagnostic, prognostic and therapeutic response biomarkers for kidney diseases, hopefully in the next few years.

Antidiabetic and renoprotective effect of Anogeissus acuminata leaf extract on experimentally induced diabetic nephropathy

Background Diabetic nephropathy is the leading cause of end-stage renal disease. Hyperglycemia, oxidative stress, and inflammation are some of the mechanisms involved in renal damage. Anogeissus acuminata (AA) is used in India as an antidiabetic agent and has potent antioxidant activity. However, it has never been evaluated for its effect on diabetic nephropathy. Hence, in the present study we aimed to evaluate its effect on streptozotocin-induced diabetes mellitus and its renal complications. Methods Diabetes mellitus was induced by injecting streptozotocin, 50 mg/kg, i.p. in rats fasted for 6 h. Rats with hyperglycemia were treated with extracts of AA for 8 weeks at doses of 100 and 300 mg/kg, orally. Human NPH insulin (4 IU/kg, s.c.) was used as standard treatment. Plasma glucose levels (at weeks 1, 2, 4, and 8) and oxidative stress parameters (at weeks 2 and 4) were assessed. Effect on diabetic nephropathy was evaluated by recording the urinary volume, urinary protein excretion, kidney weights, serum creatinine, and blood urea nitrogen levels at week 8. Results Methanolic extract of AA leaves produced statistically significant (p<0.05) hypoglycemic and antioxidant effect. It also resulted in improved urinary function, reflected by better urinary volume and reduced protein excretion in urine. AA treatment could prevent the elevation of serum creatinine and blood urea nitrogen level in a dose-dependent manner. Kidney hypertrophy could be attenuated remarkably, as reflected by the significantly lower kidney weight (KW) per 100 g body weight (p<0.05). Conclusions AA leaf extract attenuated the development of diabetic nephropathy and also demonstrated antidiabetic and antioxidant action.

EET enhances renal function in obese mice resulting in restoration of HO-1-Mfn1/2 signaling, and decrease in hypertension through inhibition of sodium chloride co-transporter

BACKGROUND

We have previously reported that epoxyeicosatrienoic acid (EET) has multiple beneficial effects on renal and adipose tissue function, in addition to its vasodilatory action; it increases insulin sensitivity and inhibits inflammation. In an examination of the signaling mechanisms by which EET reduces renal and peri-renal fat function, we hypothesized that EET ameliorates obesity-induced renal dysfunction by improving sodium excretion, reducing the sodium-chloride cotransporter NCC, lowering blood pressure, and enhancing mitochondrial and thermogenic gene levels in PGC-1α dependent mice.

METHODS

EET-agonist treatment normalized glucose metabolism, renal ENaC and NCC protein expression, urinary sodium excretion and blood pressure in obese (db/db) mice. A marked improvement in mitochondrial integrity, thermogenic genes, and PGC-1α-HO-1-adiponectin signaling occurred. Knockout of PGC-1α in EET-treated mice resulted in a reversal of these beneficial effects including a decrease in sodium excretion, elevation of blood pressure and an increase in the pro-inflammatory adipokine nephroblastoma overexpressed gene (NOV). In the elucidation of the effects of EET on peri-renal adipose tissue, EET increased adiponectin, mitochondrial integrity, thermogenic genes and decreased NOV, i.e. "Browning' peri-renal adipose phenotype that occurs under high fat diets. Taken together, these data demonstrate a critical role of an EET agonist in the restoration of healthy adipose tissue with reduced release of inflammatory molecules, such as AngII and NOV, thereby preventing their detrimental impact on sodium absorption and NCC levels and the development of obesity-induced renal dysfunction.

CKD and ESRD in US Hispanics

Hispanics are the largest racial/ethnic minority group in the United States, and they experience a substantial burden of kidney disease. Although the prevalence of chronic kidney disease (CKD) is similar or slightly lower in Hispanics than non-Hispanic whites, the age- and sex-adjusted prevalence rate of end-stage renal disease is almost 50% higher in Hispanics compared with non-Hispanic whites. This has been attributed in part to faster CKD progression among Hispanics. Furthermore, Hispanic ethnicity has been associated with a greater prevalence of cardiovascular disease risk factors, including obesity and diabetes, as well as CKD-related complications. Despite their less favorable socioeconomic status, which often leads to limited access to quality health care, and their high comorbid condition burden, the risk for mortality among Hispanics appears to be lower than for non-Hispanic whites. This survival paradox has been attributed to a complex interplay between sociocultural and psychosocial factors, as well as other factors. Future research should focus on evaluating the long-term impact of these factors on patient-centered and clinical outcomes. National policies are needed to improve access to and quality of health care among Hispanics with CKD.

The therapeutic potential of targeting the peripheral endocannabinoid/CB1 receptor system

Endocannabinoids (eCBs) are internal lipid mediators recognized by the cannabinoid-1 and -2 receptors (CB₁R and CB₂R, respectively), which also mediate the different physiological effects of marijuana. The endocannabinoid system, consisting of eCBs, their receptors, and the enzymes involved in their biosynthesis and degradation, is present in a vast number of peripheral organs. In this review we describe the role of the eCB/CB₁R system in modulating the metabolism in several peripheral organs. We assess how eCBs, via activating the CB₁R, contribute to obesity and regulate food intake. In addition, we describe their roles in modulating liver and kidney functions, as well as bone remodeling and mass. Special importance is given to emphasizing the efficacy of the recently developed peripherally restricted CB₁R antagonists, which were pre-clinically tested in the management of energy homeostasis, and in ameliorating both obesity- and diabetes-induced metabolic complications.

The renin-angiotensin-aldosterone system blockade in patients with advanced diabetic kidney disease

BACKGROUND AND OBJECTIVES

Diabetic kidney disease is the leading cause of end-stage chronic kidney disease. The renin-angiotensin-aldosterone system (RAAS) blockade has been shown to slow the progression of diabetic kidney disease. Our objectives were: to study the percentage of patients with diabetic kidney disease treated with RAAS blockade, to determine its renal function, safety profile and assess whether its administration is associated with increased progression of CKD after 3 years of follow-up.

MATERIALS AND METHODS

Retrospective study. 197 diabetic kidney disease patients were included and divided into three groups according to the treatment: patients who had never received RAAS blockade (non-RAAS blockade), patients who at some point had received RAAS blockade (inconstant-RAAS blockade) and patients who received RAAS blockade (constant-RAAS blockade). Clinical characteristics and analytical variables such as renal function, electrolytes, glycosylated haemoglobin and glomerular filtration rate according to chronic kidney disease -EPI and MDRD formulas were assessed. We also studied their clinical course (baseline, 1 and 3 years follow-up) in terms of treatment group, survival, risk factors and renal prognosis.

RESULTS

Non-RAAS blockade patients had worse renal function and older age (p<0.05) at baseline compared to RAAS blockade patients. Patients who received RAAS blockade were not found to have greater toxicity or chronic kidney disease progression and no differences in renal prognosis were identified. Mortality was higher in non-RAAS blockade patients, older patients and patients with worse renal function (p<0.05). In the multivariate analysis, older age and worse renal function were risk factors for mortality.

CONCLUSIONS

Treatment with RAAS blockade is more common in diabetic kidney disease patients with eGFR≥30ml/min/1.73m². In our study, there were no differences in the evolution of renal function between the three groups. Older age and worse renal function were associated with higher mortality in patients who did not receive RAAS blockade.

Reduction in microalbuminuria by calcium channel blockers in patients with type 2 diabetes mellitus and hypertension-A randomized, open-label, active-controlled, superiority, parallel-group clinical trial

BACKGROUND

It has been suggested that renoprotection with calcium channel blockers (CCBs) may differ. This study aimed to compare the anti-proteinuric effect of different CCBs in patients with type 2 diabetes (T2D).

METHODS

A multicentre, randomized, open-label, active-controlled study was performed in seven centres in Korea. A total of 74 patients with T2D and microalbuminuria treated with renin-angiotensin system (RAS) blockers were randomized to a cilnidipine 10 mg treatment (n=38) or amlodipine 5 mg treatment (n=36).

RESULTS

Urine albumin to creatinine ratio (ACR) reduction was similar between the two groups at 12 weeks (-53.0±123.2 mg/g in cilnidipine group and -35.7±83.6 mg/g in amlodipine group, P=.29) or 24 weeks (-57.3±106.9 mg/g in cilnidipine group and -20.0±110.4 mg/g in amlodipine group, P=.24). In a subgroup analysis, cilnidipine treatment showed a larger ACR reduction than amlodipine treatment at 12 weeks (-84.7±106.8 mg/g in cilnidipine group and -9.5±79.2 mg/g in amlodipine group, P=.01) and 24 weeks (-84.0±111.7 mg/g in cilnidipine group and 14.6±119.4 mg/g in amlodipine group, P=.008), particularly in patients with a longer duration of diabetes more than 10 years.

CONCLUSIONS

Cilnidipine did not show any additional anti-albuminuric effect compared with amlodipine in patients with T2D and microalbuminuria treated with an RAS blocker. However, the anti-albuminuric effect of cilnidipine might differ according to the duration of diabetes.

Proximal Tubular Cannabinoid-1 Receptor Regulates Obesity-Induced CKD

Obesity-related structural and functional changes in the kidney develop early in the course of obesity and occur independently of hypertension, diabetes, and dyslipidemia. Activating the renal cannabinoid-1 receptor (CB₁R) induces nephropathy, whereas CB₁R blockade improves kidney function. Whether these effects are mediated via a specific cell type within the kidney remains unknown. Here, we show that specific deletion of CB₁R in the renal proximal tubule cells did not protect the mice from obesity, but markedly attenuated the obesity-induced lipid accumulation in the kidney and renal dysfunction, injury, inflammation, and fibrosis. These effects associated with increased activation of liver kinase B1 and the energy sensor AMP-activated protein kinase, as well as enhanced fatty acid β-oxidation. Collectively, these findings indicate that renal proximal tubule cell CB₁R contributes to the pathogenesis of obesity-induced renal lipotoxicity and nephropathy by regulating the liver kinase B1/AMP-activated protein kinase signaling pathway.

The role of novel biomarkers in predicting diabetic nephropathy: a review

Diabetic nephropathy (DN) is one of the microvascular complications of the kidney arising commonly from type 1 diabetes mellitus (T1DM), and occasionally from type 2 diabetes mellitus (T2DM). Microalbuminuria serves as an early indicator of DN risk and a predictor of its progression as well as cardiovascular disease risk in both T1DM and T2DM. Although microalbuminuria remains the gold standard for early detection of DN, it is not a sufficiently accurate predictor of DN risk due to some limitations. Thus, there is a paradigm shift to novel biomarkers which would help to predict DN risk early enough and possibly prevent the occurrence of end-stage kidney disease. These new biomarkers have been broadly classified into glomerular biomarkers, tubular biomarkers, biomarkers of inflammation, biomarkers of oxidative stress, and miscellaneous biomarkers which also include podocyte biomarkers, some of which are also considered as tubular and glomerular biomarkers. Although they are potentially useful for the evaluation of DN, current data still preclude the routine clinical use of majority of them. However, their validation using high-quality and large longitudinal studies is of paramount importance, as well as the subsequent development of a biomarker panel which can reliably predict and evaluate this renal microvascular disease. This paper aims to review the predictive role of these biomarkers in the evaluation of DN.

Evaluation of the angiotensin II receptor blocker azilsartan medoxomil in African‐American patients with hypertension

The efficacy and safety of azilsartan medoxomil (AZL‐M) were evaluated in African‐American patients with hypertension in a 6‐week, double‐blind, randomized, placebo‐controlled trial, for which the primary end point was change from baseline in 24‐hour mean systolic blood pressure (BP). There were 413 patients, with a mean age of 52 years, 57% women, and baseline 24‐hour BP of 146/91 mm Hg. Treatment differences in 24‐hour systolic BP between AZL‐M 40 mg and placebo (−5.0 mm Hg; 95% confidence interval, −8.0 to −2.0) and AZL‐M 80 mg and placebo (−7.8 mm Hg; 95% confidence interval, −10.7 to −4.9) were significant (P≤.001 vs placebo for both comparisons). Changes in the clinic BPs were similar to the ambulatory BP results. Incidence rates of adverse events were comparable among the treatment groups, including those of a serious nature. In African‐American patients with hypertension, AZL‐M significantly reduced ambulatory and clinic BPs in a dose‐dependent manner and was well tolerated.

The emerging role of the endocannabinoid system in the pathogenesis and treatment of kidney diseases

Endocannabinoids (eCBs) are endogenous lipid ligands that bind to cannabinoid receptors that also mediate the effects of marijuana. The eCB system is comprised of eCBs, anandamide, and 2-arachidonoyl glycerol, their cannabinoid-1 and cannabinoid-2 receptors (CB1 and CB2, respectively), and the enzymes involved in their biosynthesis and degradation. It is present in both the central nervous system and peripheral organs including the kidney. The current review focuses on the role of the eCB system in normal kidney function and various diseases, such as diabetes and obesity, that directly contributes to the development of renal pathologies. Normally, activation of the CB1 receptor regulates renal vascular hemodynamics and stimulates the transport of ions and proteins in different nephron compartments. In various mouse and rat models of obesity and type 1 and 2 diabetes mellitus, eCBs generated in various renal cells activate CB1 receptors and contribute to the development of oxidative stress, inflammation, and renal fibrosis. These effects can be chronically ameliorated by CB1 receptor blockers. In contrast, activation of the renal CB2 receptors reduces the deleterious effects of these chronic diseases. Because the therapeutic potential of globally acting CB1 receptor antagonists in these conditions is limited due to their neuropsychiatric adverse effects, the recent development of peripherally restricted CB1 receptor antagonists may represent a novel pharmacological approach in treating renal diseases.

Place of sodium-glucose cotransporter-2 inhibitors in East Asian subjects with type 2 diabetes mellitus: Insights into the management of Asian phenotype

The burden of type 2 diabetes (T2DM) in East Asia is alarming. Rapid modernization and urbanization have led to major lifestyle changes and a tremendous increase in the prevalence of obesity, metabolic syndrome, and diabetes mellitus. The development of T2DM at a younger age, with lower body mass index, higher visceral adiposity, and more significant pancreatic beta-cell dysfunction compared to Caucasians are factors responsible for the increased prevalence of T2DM in East Asians. Sodium-glucose Cotransporter-2 (SGLT2) inhibitors (canagliflozin, dapaglifozin, empagliflozin, etc.) reduce renal glucose reabsorption, leading to favorable effects on glycemic, blood pressure, and weight control. The insulin-independent mechanism enables their use as monotherapy or combination therapy with insulin and other oral antidiabetic agents. The role of SGLT2 inhibitors in the management of T2DM among East Asians is an interesting area of research, given that East Asians have been proven to be uniquely different from Caucasians. This review provides comprehensive coverage of the available literature not only on the efficacy and safety, but also on the recent cardiovascular and renal outcomes of SGLT2 inhibitors, focusing among East Asians.

Obese and diabetic patients with end-stage renal disease: Peritoneal dialysis or hemodialysis?

Obesity is a chronic disease that is increasingly prevalent around the world and is a well-recognized risk factor for type 2 diabetes and hypertension, leading causes of end-stage renal disease (ESRD). The obese diabetic patient with ESRD is a challenge for the nephrologist with regard to the type of renal replacement therapy that should be suggested and offered to the patient. There is no evidence that either peritoneal dialysis or hemodialysis is contraindicated in obese ESRD patients. In the literature, we can find a discrepancy in the impact of obesity on mortality among hemodialysis vs. peritoneal dialysis patients. Several studies in hemodialysis patients suggest that a higher BMI confers a survival advantage - the so-called "reverse epidemiology". In contrast, the literature among obese peritoneal dialysis patients is inconsistent, with various studies reporting an increased risk of death, no difference, or a decreased risk of death. Many of these studies only spanned across a few years, and this is probably too short of a time frame for a realistic assessment of obesity's impact on mortality in ESRD patients. The decision for dialysis modality in an obese diabetic patient with ESRD should be individualized. According to the results of published studies, we cannot suggest PD or HD as a better solution for all obese diabetic patients. The obese patient should be educated about all their dialysis options, including home dialysis therapies. In this review, the available literature related to the dialysis modality in obese patients with diabetes and ESRD was reviewed.

CKD Progression and Mortality among Hispanics and Non-Hispanics

Although recommended approaches to CKD management are achieved less often in Hispanics than in non-Hispanics, whether long-term outcomes differ between these groups is unclear. In a prospective longitudinal analysis of participants enrolled into the Chronic Renal Insufficiency Cohort (CRIC) and Hispanic-CRIC Studies, we used Cox proportional hazards models to determine the association between race/ethnicity, CKD progression (50% eGFR loss or incident ESRD), incident ESRD, and all-cause mortality, and linear mixed-effects models to assess differences in eGFR slope. Among 3785 participants, 13% were Hispanic, 43% were non-Hispanic white (NHW), and 44% were non-Hispanic black (NHB). Over a median follow-up of 5.1 years for Hispanics and 6.8 years for non-Hispanics, 27.6% of all participants had CKD progression, 21.3% reached incident ESRD, and 18.3% died. Hispanics had significantly higher rates of CKD progression, incident ESRD, and mean annual decline in eGFR than did NHW (P<0.05) but not NHB. Hispanics had a mortality rate similar to that of NHW but lower than that of NHB (P<0.05). In adjusted analyses, the risk of CKD progression did not differ between Hispanics and NHW or NHB. However, among nondiabetic participants, compared with NHB, Hispanics had a lower risk of CKD progression (hazard ratio, 0.61; 95% confidence interval, 0.39 to 0.95) and incident ESRD (hazard ratio, 0.50; 95% confidence interval, 0.30 to 0.84). At higher levels of urine protein, Hispanics had a significantly lower risk of mortality than did non-Hispanics (P<0.05). Thus, important differences in CKD progression and mortality exist between Hispanics and non-Hispanics and may be affected by proteinuria and diabetes.

The Role of Galectin-3 in the Kidneys

Galectin-3 is a 32- to 35-kDa member of the galectin family of b-galactoside-binding lectins, which is characterized by a carbohydrate recognition domain. Through its carbohydrate-binding function, it regulates cell growth, differentiation, and inflammation. It also plays a complex, context-dependent role in the kidneys. During development, it promotes nephrogenesis and is strongly expressed in the ureteric bud and its derivatives. An increase in the concentration of galectin-3 has been reported to be associated with fibrosis of the kidneys. Elevated levels of plasma galectin-3 are also associated with increased risks of rapid renal function decline, incident chronic kidney disease, and progressive renal impairment, and also with cardiovascular end points, infection, and all-cause mortality in patients with renal function impairment. This review discusses a general survey on galectin-3 expressions in nephrogenesis, kidney injury animal models, clinical renal diseases, renal transplantation and the potential role of galectin-3 for treatment in kidney disease.

Assessment of Neutrophil Gelatinase-Associated Lipocalin (NGAL) and Retinol-Binding Protein 4 (RBP4) in Type 2 Diabetic Patients with Nephropathy

Diabetic nephropathy (DN) is one of the most serious microvascular complications of diabetes. The study aims to evaluate the diagnostic value of serum neutrophil gelatinase-associated lipocalin (NGAL) and retinol-binding protein 4 (RBP4) as biomarkers for early detection of nephropathy in type 2 diabetic patients. The current study was performed on 150 type 2 diabetic patients. These patients were classified into three equal groups according to their albumin/creatinine ratio (ACR), including patients with normoalbuminuria (ACR <30 mg/g creatinine), patients with microalbuminuria (ACR = 30-300 mg/g creatinine), and patients with macroalbuminuria (ACR >300 mg/g creatinine). Fifty apparently healthy subjects matching the same age and socioeconomic status with diabetic subjects were selected as a control group. The plasma glucose, insulin, glycosylated hemoglobin (HbA1c), homeostasis model assessment of insulin resistance (HOMA-IR), lipid profile, urea, creatinine, cystatin C, glomerular filtration rate (GFR), NGAL, and RBP4 were measured in the studied groups. Significantly elevated NGAL and RBP4 levels were observed in micro- and macroalbuminuric diabetic groups when compared to the control and normoalbuminuric diabetic groups. NGAL and RBP4 were found to correlate positively with duration of diabetes, systolic and diastolic blood pressure, glucose, HbA1c, HOMA-IR, triacylglycerol, and ACR, but correlate inversely with GFR in DN groups. Receiver operating characteristic curves revealed that for early detection of DN, the best cutoff values to discriminate DN and diabetic without nephropathy groups were 91.5 ng/mL for NGAL with 87% sensitivity, 74% specificity, and area under the curve (AUC) = 0.881; 24.5 ng/mL for RBP4 with 84% sensitivity, 90% specificity, and AUC = 0.912; and 37.5 mg/g creatinine for ACR with 89% sensitivity, 72% specificity, and AUC = 0.819. RBP4 is more specific (90% specificity) than NGAL (74% specificity) and ACR (72% specificity). Therefore, RBP4 marker may serve as a tool to follow-up clinical monitoring of the development and progression of DN.

Ethnic/Race Diversity and Diabetic Kidney Disease

Ethnicity and race are often used interchangeably in the literature. However, the traditional definition of race and ethnicity is related to biological (bone structure and skin, hair, or eye color) and sociological factors (nationality, regional culture, ancestry, and language) respectively. Diabetes mellitus (DM) is a huge global public health problem. As the number of individuals with Type 2 DM grows, the prevalence of diabetic kidney disease (DKD), which is one of the most serious complications, is expected to rise sharply. Many ethnic and racial groups have a greater risk of developing DM and its associated macro and micro-vascular complications.

Relative risks of chronic kidney disease for mortality and end-stage renal disease across races are similar

Some suggest race-specific cutpoints for kidney measures to define and stage chronic kidney disease (CKD), but evidence for race-specific clinical impact is limited. To address this issue, we compared hazard ratios of estimated glomerular filtration rates (eGFR) and albuminuria across races using meta-regression in 1.1 million adults (75% Asians, 21% Whites, and 4% Blacks) from 45 cohorts. Results came mainly from 25 general population cohorts comprising 0.9 million individuals. The associations of lower eGFR and higher albuminuria with mortality and end-stage renal disease (ESRD) were largely similar across races. For example, in Asians, Whites, and Blacks, the adjusted hazard ratios (95% confidence interval) for eGFR 45-59 versus 90-104 ml/min per 1.73 m(2) were 1.3 (1.2-1.3), 1.1 (1.0-1.2), and 1.3 (1.1-1.7) for all-cause mortality, 1.6 (1.5-1.7), 1.4 (1.2-1.7), and 1.4 (0.7-2.9) for cardiovascular mortality, and 27.6 (11.1-68.7), 11.2 (6.0-20.9), and 4.1 (2.2-7.5) for ESRD, respectively. The corresponding hazard ratios for urine albumin-to-creatinine ratio 30-299 mg/g or dipstick 1+ versus an albumin-to-creatinine ratio under 10 or dipstick negative were 1.6 (1.4-1.8), 1.7 (1.5-1.9), and 1.8 (1.7-2.1) for all-cause mortality, 1.7 (1.4-2.0), 1.8 (1.5-2.1), and 2.8 (2.2-3.6) for cardiovascular mortality, and 7.4 (2.0-27.6), 4.0 (2.8-5.9), and 5.6 (3.4-9.2) for ESRD, respectively. Thus, the relative mortality or ESRD risks of lower eGFR and higher albuminuria were largely similar among three major races, supporting similar clinical approach to CKD definition and staging, across races.

African Americans, hypertension and the renin angiotensin system

African Americans have exceptionally high rates of hypertension and hypertension related complications. It is commonly reported that the blood pressure lowering efficacy of renin angiotensin system (RAS) inhibitors is attenuated in African Americans due to a greater likelihood of having a low renin profile. Therefore these agents are often not recommended as initial therapy in African Americans with hypertension. However, the high prevalence of comorbid conditions, such as diabetes, cardiovascular and chronic kidney disease makes treatment with RAS inhibitors more compelling. Despite lower circulating renin levels and a less significant fall in blood pressure in response to RAS inhibitors in African Americans, numerous clinical trials support the efficacy of RAS inhibitors to improve clinical outcomes in this population, especially in those with hypertension and risk factors for cardiovascular and related diseases. Here, we discuss the rationale of RAS blockade as part of a comprehensive approach to attenuate the high rates of premature morbidity and mortality associated with hypertension among African Americans.

Pathophysiology of proteinuria and its value as an outcome measure in chronic kidney disease

Chronic kidney diseases share common pathogenic mechanisms that, independently from the initial injury, lead to glomerular hyperfiltration, proteinuria, and progressive renal scarring and function loss. Consistent experimental evidence supports the crucial role of proteinuria in accelerating kidney disease progression to end-stage renal failure through multiple pathways, including induction of tubular chemokine expression and complement activation. These events, in turn, lead to inflammatory cell infiltration in the interstitium and sustained fibrogenesis. The extent of proteinuria is widely recognized as a marker of the severity of chronic kidney disease and as a predictor of future decline in glomerular filtration rate. More importantly, a reduction in proteinuria invariably translates into a protection from renal function decline in patients with diabetic and non-diabetic renal disease. Recent evidence also showed the existence of a relationship between proteinuria levels and cardiovascular risk, which extends to the range of urinary albumin excretion that was previously thought 'normal'. Thus, proteinuria should be considered a valuable surrogate end point for clinical trials in patients with chronic renal diseases and a target for reno- and cardioprotecive strategies.

What should be the blood pressure target for patients with chronic kidney disease?

PURPOSE OF REVIEW

Persons with chronic kidney disease (CKD) exhibit a disproportionate burden of elevated blood pressure (BP) with a high prevalence of premature end-stage renal disease and cardiovascular events.

RECENT FINDINGS

Results of recent randomized controlled clinical trials suggest that most patients with reduced estimated glomerular filtration rate (eGFR) and hypertension experience optimal clinical outcomes when SBP is less than 140 mmHg and DBP is less than 90 mmHg. The benefit of additional lowering of SBP to less than 130 mmHg and DBP to less than 80 mmHg remains controversial, and appears to be of most benefit to the subset of CKD patients with proteinuria (>300 mg/day). The combination of a diuretic and an angiotensin receptor blocker (ARB) or angiotensin-converting enzyme inhibitor (ACEI) has demonstrated particular promise in patients with reduced eGFR and proteinuria.

SUMMARY

A practical approach in clinical practice for the treatment of elevated BP in persons with CKD is to achieve a BP less than 140/90 mmHg with a combination of diuretic and an ARB or ACEI. Consideration for a lower BP goal and other therapeutic and nontherapeutic interventions can be made based on the cause of CKD, presence of proteinuria, or other coexisting medical conditions.

The effect of RAAS blockade on the progression of diabetic nephropathy

The renin-angiotensin-aldosterone system (RAAS) has a key role in the regulation of blood pressure, sodium and water balance, and cardiovascular and renal homeostasis. In diabetic nephropathy, excessive activation of the RAAS results in progressive renal damage. RAAS blockade using angiotensin-converting-enzyme inhibitors or angiotensin-receptor blockers is the cornerstone of treatment of diabetic renal disease. Alternative RAAS-blockade strategies include renin inhibition and aldosterone blockade. Data from small initial studies of these agents are promising. However, single-agent interventions do not fully block the RAAS and patients treated with these therapies remain at high residual renal risk. Approaches to optimize drug responses include dietary changes and increasing dosages. The theoretically attractive option of combining different RAAS interventions has also been tested in clinical trials but long-term outcomes were disappointing. However, dual RAAS blockade might represent a good therapeutic option for specific patients. A better knowledge of the pathophysiology of the RAAS is crucial to fully understand the mechanisms of action of RAAS blockers and to exploit their renoprotective effects. Moreover, lifestyle interventions or diagnostic tools might be used to optimize RAAS blockade and identify those patients who are most likely to benefit from the therapy.

CKD and cardiovascular disease in the Atherosclerosis Risk in Communities (ARIC) study: interactions with age, sex, and race

BACKGROUND

Estimated glomerular filtration rate (eGFR) and albuminuria are central for diagnosis, staging, and risk evaluation in chronic kidney disease (CKD). Universal thresholds regardless of age, sex, and race are recommended, but relatively little is known about how these demographic factors alter the relationship of eGFR and albuminuria to cardiovascular outcomes.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

11,060 whites and blacks aged 52-75 years in the Atherosclerosis Risk in Communities (ARIC) Study with median follow-up of 11.2 years.

PREDICTORS

eGFR by the CKD-EPI (CKD Epidemiology Collaboration) creatinine equation (reference, 95 mL/min/1.73 m(2)) and urinary albumin-creatinine ratio (ACR; reference, 5 mg/g).

OUTCOMES

Cardiovascular events (coronary disease, stroke, and heart failure) and all-cause mortality.

MEASUREMENTS

Adjusted HRs associated with eGFR and ACR in subgroups according to age, sex, and race.

RESULTS

Cardiovascular risk significantly increased at eGFR <70 mL/min/1.73 m(2) in all subgroups according to age (<65 vs ≥65 years), sex, and race (P for interaction >0.2 for these subgroups; eg, at eGFR of 30 mL/min/1.73 m(2), the adjusted HR was 2.19 [95% CI, 1.10-4.35] at age 52-64 years vs 2.23 [95% CI, 1.33-3.72] at age 65-75 years). Results were similar for mortality. Log(ACR) was associated linearly with cardiovascular risk without threshold effects in all subgroups, with some quantitative interactions. HRs according to ACR tended to be lower in men versus women (eg, at ACR of 40 mg/g, 1.18 [95% CI, 0.98-1.41] vs 1.77 [95% CI, 1.45-2.15]) and in the older versus younger population (1.24 [95% CI, 1.04-1.49] vs 1.73 [95% CI, 1.42-2.12]; P for interaction <0.01 for sex and age). Less evident interactions were observed for mortality.

LIMITATIONS

Single measurement of eGFR with creatinine and ACR and relatively narrow age range.

CONCLUSIONS

The associations of eGFR and ACR with cardiovascular events were largely similar, with some quantitative interactions, in age, sex, and racial subgroups, generally supporting universal thresholds of GFR and ACR for CKD definition/staging.

Hypertension in black patients: an update

Black individuals are at high risk for hypertension and increased morbidity from cardiovascular and renal disease, in particular. Increased understanding of racial disparities in hypertension, in terms of risk factors, patient/physician behaviors, and treatment outcomes, is key to improving racially oriented care in black patients. Recent data suggest that black patients progress more rapidly from prehypertension to hypertension, highlighting the need for early and prompt intervention. Unfortunately, adherence to and persistence with antihypertensive therapy are generally poor in black patients and are compounded by the increased need for multidrug therapy in this patient population. Treatment strategies currently under investigation are focusing on methods to improve self-care behaviors and medication adherence. Because this is a constantly and rapidly evolving field of study, this article provides an update of recent findings that should be of relevance and interest to practicing clinicians.

Iron restriction prevents diabetic nephropathy in Otsuka Long-Evans Tokushima fatty rat

High body iron levels are found in type 2 diabetes mellitus (DM). Iron excess leads to tissue injury through free radical formation. We investigated the effect of iron restriction on renal damage in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of type 2 DM. OLETF rats (n = 18) were divided into three groups at 10 weeks of age: high fat diet containing 8% NaCl (HFS, n = 6), HFS diet with iron restricted (HFS + IR, n = 6), and HFS with hydralazine (HFS + Hyd, n = 6). Long-Evans Tokushima (LETO) rats served as control. Iron restriction decreased hemoglobin levels, systolic blood pressure, and urinary excretion of protein and 8-hydroxy-2'-deoxyguanosine in the OLETF rats fed with HFS diet. Compared to the HFS group, the expression of desmin, renal glomerular injury marker and iron deposition in the renal tubules were attenuated in the HFS + IR group but not in the HFS + Hyd group at 26 weeks of age. Moreover, renal hypoxia (evaluated as pimonidazole adducts) was improved in the HFS + IR group compared to the HFS group in spite of anemia. Iron restriction prevented the production of reactive oxygen species and the development of early stage nephropathy in OLETF rats. Iron restriction may be beneficial in prevention of nephropathy in type 2 DM.

The antioxidant silybin prevents high glucose-induced oxidative stress and podocyte injury in vitro and in vivo

Podocyte injury, a major contributor to the pathogenesis of diabetic nephropathy, is caused at least in part by the excessive generation of reactive oxygen species (ROS). Overproduction of superoxide by the NADPH oxidase isoform Nox4 plays an important role in podocyte injury. The plant extract silymarin is attributed antioxidant and antiproteinuric effects in humans and in animal models of diabetic nephropathy. We investigated the effect of silybin, the active constituent of silymarin, in cultures of mouse podocytes and in the OVE26 mouse, a model of type 1 diabetes mellitus and diabetic nephropathy. Exposure of podocytes to high glucose (HG) increased 60% the intracellular superoxide production, 90% the NADPH oxidase activity, 100% the Nox4 expression, and 150% the number of apoptotic cells, effects that were completely blocked by 10 μM silybin. These in vitro observations were confirmed by similar in vivo findings. The kidney cortex of vehicle-treated control OVE26 mice displayed greater Nox4 expression and twice as much superoxide production than cortex of silybin-treated mice. The glomeruli of control OVE26 mice displayed 35% podocyte drop out that was not present in the silybin-treated mice. Finally, the OVE26 mice experienced 54% more pronounced albuminuria than the silybin-treated animals. In conclusion, this study demonstrates a protective effect of silybin against HG-induced podocyte injury and extends this finding to an animal model of diabetic nephropathy.

Elevated galectin-3 precedes the development of CKD

Galectin-3, a profibrotic mediator, is linked to the development of renal fibrosis in animal models and inversely correlates with GFR in humans, but whether galectin-3 predicts incident kidney disease is unknown. Here, we assessed renal outcomes for 2450 Framingham Offspring participants who attended examination 6 (1995-1998) and had follow-up data at examination 8 (2005-2008). Renal outcomes of interest included rapid decline in renal function (≥3 ml/min per 1.73 m(2) per year decline in estimated GFR [eGFR]), CKD (eGFR < 60 ml/min per 1.73 m(2)), and albuminuria (albumin-to-creatinine ratio ≥17 mg/g in men or ≥25 mg/g in women). We used multivariable logistic regression models to evaluate associations between galectin-3 with incident renal outcomes at examination 8. During a mean follow-up of 10.1 years, GFR declined rapidly in 241 (9.2%) participants, incident CKD developed in 277 (11.3%), and albuminuria developed in 194 (10.1%). Higher plasma levels of galectin-3 were associated with rapid decline in eGFR (per 1-SD log-galectin-3; adjusted odds ratio [OR], 1.49; 95% confidence interval [CI], 1.28 to 1.73]) and a higher risk of incident CKD (OR, 1.47; 95% CI, 1.27 to 1.71), but not with the risk of incident albuminuria. The addition of galectin-3 to clinical predictors improved the C-statistic (0.837-0.845; P=0.02) but did not reach predefined thresholds for clinically significant improvements to risk prediction based on reclassification indices. In conclusion, elevated levels of plasma galectin-3 are associated with increased risks of rapid GFR decline and of incident CKD in the community, which calls for further study in higher-risk groups.

Trends in relative mortality between Hispanic and non-Hispanic whites initiating dialysis: a retrospective study of the US Renal Data System

BACKGROUND

Hispanic patients undergoing long-term dialysis experience better survival compared with non-Hispanic whites. It is unknown whether this association differs by age, has changed over time, or is due to differential access to kidney transplantation.

STUDY DESIGN

National retrospective cohort study.

SETTING & PARTICIPANTS

Using the US Renal Data System, we identified 615,618 white patients 18 years or older who initiated dialysis therapy between January 1, 1995, and December 31, 2007.

PREDICTORS

Hispanic ethnicity (vs non-Hispanic whites), year of end-stage renal disease incidence, age (as potential effect modifier).

OUTCOMES

All-cause and cause-specific mortality.

RESULTS

We found that Hispanics initiating dialysis therapy experienced lower mortality, but age modified this association (P < 0.001). Compared with non-Hispanic whites, mortality in Hispanics was 33% lower at ages 18-39 years (adjusted cause-specific HR [HRcs], 0.67; 95% CI, 0.64-0.71) and 40-59 years (HRcs, 0.67; 95% CI, 0.66-0.68), 19% lower at ages 60-79 years (HRcs, 0.81; 95% CI, 0.80-0.82), and 6% lower at 80 years or older (HRcs, 0.94; 95% CI, 0.91-0.97). Accounting for the differential rates of kidney transplantation, the associations were attenuated markedly in the younger age strata; the survival benefit for Hispanics was reduced from 33% to 10% at ages 18-39 years (adjusted subdistribution-specific HR [HRsd], 0.90; 95% CI, 0.85-0.94) and from 33% to 19% among those aged 40-59 years (HRsd, 0.81; 95% CI, 0.80-0.83).

LIMITATIONS

Inability to analyze Hispanic subgroups that may experience heterogeneous mortality outcomes.

CONCLUSIONS

Overall, Hispanics experienced lower mortality, but differential access to kidney transplantation was responsible for much of the apparent survival benefit noted in younger Hispanics.

Clinical value of NGAL, L-FABP and albuminuria in predicting GFR decline in type 2 diabetes mellitus patients

OBJECTIVES

Neutrophil gelatinase-associated lipocalin (NGAL) and liver-type fatty acid binding protein (L-FABP) are emerging as excellent biomarkers in the urine and plasma for the early prediction of acute and chronic kidney injury. The aims of this prospective study were to determine the role of albuminuria, and that of serum and urine levels of NGAL and L-FABP as predictors of a decline in the glomerular filtration rate (GFR) in patients with type 2 diabetes.

METHODS

A longitudinal cohort study with one hundred forty type 2 diabetic patients was conducted. Serum and urine levels of NGAL and L-FABP, and the urine albumin excretion rate were determined. The correlation between the kidney injury biomarkers and rate of GFR decline was analyzed.

RESULTS

The eGFR of study subjects decreased significantly as the study progressed (86.4±31.1 vs. 74.4±27.3 ml/min/1.73 m(2), P<0.001), and the urine albumin excretion rate increased significantly (264.9±1060.3 vs. 557.7±2092.5 mg/day, P = 0.009). The baseline urine albumin excretion rate and serum L-FABP level were significantly correlated with baseline eGFR (P<0.05). The results of regression analysis for the correlations between the rate of eGFR change and the baseline levels of NGAL and L-FABP, and the urine albumin excretion rate showed that only the urine albumin excretion rate was significantly correlated with the rate of eGFR change (standardized coefficients: -0.378; t: -4.298; P<0.001).

CONCLUSIONS

Tubular markers, such as NGAL and L-FABP, may not be predictive factors associated with GFR decline in type 2 diabetic patients.

Obesity and diabetic kidney disease

Obesity and diabetes are major causes of CKD and ESRD, and are thus enormous health concerns worldwide. Both obesity and diabetes, along with other elements of the metabolic syndrome including hypertension, are highly interrelated and contribute to the development and progression of renal disease. Studies show that multiple factors act in concert to initially cause renal vasodilation, glomerular hyperfiltration, and albuminuria, leading to the development of glomerulopathy. The coexistence of hypertension contributes to the disease progression, which, if not treated, may lead to ESRD. Although early intervention and management of body weight, hyperglycemia, and hypertension are imperative, novel therapeutic approaches are also necessary to reduce the high morbidity and mortality associated with both obesity-related and diabetes-related renal disease.

Hypertensive chronic kidney disease in African Americans: strategies for improving care

African Americans have a disproportionate burden of chronic kidney disease (CKD), which tends to have an earlier onset and a more rapid progression in this population. Many of the factors responsible for the rapid progression of CKD in African Americans are detectable by screening and are modifiable with prompt therapy.

Diabetic nephropathy among Mexican Americans

The incidence of diabetic nephropathy (DN) is growing rapidly worldwide as a consequence of the rising prevalence of Type 2 diabetes mellitus (T2DM). Among U.S. ethnic groups, Mexican Americans have a disproportionately high incidence and prevalence of DN and associated end-stage renal disease (ESRD). In communities bordering Mexico, as many as 90% of Mexican American patients with ESRD also suffer from T2DM compared to only 50% of non-Hispanic Whites (NHW). Both socio-economic factors and genetic predisposition appear to have a strong influence on this association. In addition, certain pathogenetic and clinical features of T2DM and DN are different in Mexican Americans compared to NHW, raising questions as to whether the diagnostic and treatment strategies that are standard practice in the NHW patient population may not be applicable in Mexican Americans. This article reviews the epidemiology of DN in Mexican Americans, describes the pathophysiology and associated risk factors, and identifies gaps in our knowledge and understanding that needs to be addressed by future investigations.

Urinary markers of glomerular injury in diabetic nephropathy

Diabetic nephropathy, the leading cause of renal failure worldwide, affects approximately one-third of all people with diabetes. Microalbuminuria is considered the first sign and the best predictor of progression to renal failure and cardiovascular events. However, albuminuria has several limitations. Therefore, earlier, more sensitive and specific biomarkers with greater predictability are needed. The aim of this paper is to discuss the current literature on biomarkers of glomerular injury that have been implicated in diabetic kidney disease.

Proteinuria should be used as a surrogate in CKD

Surrogate end points of renal failure are instrumental to the testing of new treatments in patients with chronic kidney disease, the natural history of which is characterized by a slow, asymptomatic decline in renal function. The magnitude of proteinuria is widely recognized as a marker of the severity of glomerulopathy. Population-based studies have identified proteinuria as a predictor of future decline in glomerular filtration rate and of the development of end-stage renal disease. More importantly, a reduction in proteinuria invariably translates into a protection from renal function decline in patients with diabetic and nondiabetic renal disease with overt proteinuria. Thus, proteinuria should be considered a valuable surrogate end point for clinical trials in patients with proteinuric renal diseases.

Managing diabetes in Asia: overcoming obstacles and the role of DPP-IV inhibitors

Asia bears the world's greatest burden of type 2 diabetes (T2DM) and prevalence is increasing rapidly. Compared to other races, Asians develop T2DM younger, at a lower degree of obesity, suffer longer from its complications and die earlier. Curbing this epidemic requires an integrated, risk-based, and multidisciplinary approach. Inadequately managed T2DM has macrovascular and microvascular sequelae, Asians with T2DM being particularly susceptible to diabetic nephropathy. Earlier and more intensive monitoring and management of risk factors are required, especially for patients with, or at risk of, renal impairment. Particular challenges of T2DM management in Asia include: lack of access to specialist healthcare, insufficient clinical evaluation and delayed diagnosis. As in Caucasians, conventional treatment modalities are limited by deteriorating glycaemic control with disease progression and there is an unmet need for efficacious, safe, cost-effective and convenient pharmacotherapies for treating different stages of T2DM and preventing its complications, particularly in high-risk patients. There is a trend towards increasing use of DPP-IV inhibitors, which are no less efficacious and safe in Asians than Caucasians and may have some advantages over existing oral antidiabetic agents, particularly for certain high-risk groups. Such agents may play a significant future role in the management of T2DM.

Performance of a genetic risk score for CKD stage 3 in the general population

BACKGROUND

Recent genome-wide association studies have identified multiple genetic loci that increase the risk of chronic kidney disease (CKD) in the general population. We hypothesized that knowledge of these loci might permit improved CKD risk prediction beyond that provided by traditional phenotypic risk factors.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

Participants who attended the 15th (1977-1979) and 24th (1995-1998) examination cycles of the original cohort or the 6th (1995-1998) and 8th cycles (2005-2008) of the offspring cohort of the Framingham Heart Study (n = 2,489).

PREDICTORS

Single-nucleotide polymorphisms at 16 stage 3 CKD loci were genotyped and used to construct a genetic risk score. Standard clinical predictors of incident stage 3 CKD also were used.

OUTCOMES & MEASUREMENTS

Incident stage 3 CKD was defined as estimated glomerular filtration rate <60 mL/min/1.73 m(2) at follow-up. Participants with baseline stage 3 CKD were excluded. Logistic regression was used to generate C statistics, which measured the power of the genetic risk score to discriminate risk of incident CKD stage 3 with and without traditional risk factors.

RESULTS

There were 270 new stage 3 CKD cases during an average of 10.8 years of follow-up. Mean genetic risk score was 17.5 ± 2.8 (SD) for those who developed stage 3 CKD and 17.3 ± 2.6 for those who did not (P for genotype score difference = 0.2). The OR for stage 3 CKD was 1.06 (95% CI, 1.01-1.11; P = 0.03) per additional risk allele, adjusting for age and sex. In the age- and sex-adjusted model, the C statistic was 0.748 without the genotype score and 0.751 with the score (P difference = 0.3). The risk score was not statistically significant in a multivariable model adjusted for standard stage 3 CKD risk factors (P = 0.07).

LIMITATIONS

All participants were of European ancestry; the genotype score may not be valid in different ancestral groups.

CONCLUSIONS

A genetic score generated from 16 known CKD risk alleles did not predict new cases of stage 3 CKD in the community beyond knowledge of common clinical risk factors alone.