Protection of the kidney by thiazolidinediones: An assessment from bench to bedside

Association of metabolic syndrome and chronic kidney disease

The prevalence of kidney disease is increasing rapidly worldwide, reflecting rising rates of obesity, diabetes, and associated metabolic syndrome (MetS). Chronic kidney disease and related comorbidities such as obesity, diabetes, and hypertension place a significant financial burden on healthcare systems. Despite the widespread use of RAAS inhibitors, intensive blood pressure and glycemic control, and newer therapeutic options consisting of sodium/glucose cotransporter-2 (SGLT-2) inhibitors or glucagon-like peptide-1 (GLP-1) receptor agonists, a significant risk of progression to end-stage renal disease remains in the high-risk obese and diabetic population. The MetS is a cluster of cardiovascular risk factors that adversely affect the development and progression of chronic kidney failure. According to the criteria of the World Health Organization, it is defined by visceral adiposity, impaired glucose tolerance or insulin resistance, atherogenic dyslipidemia, raised blood pressure, and microalbuminuria with a albumin-to-creatinine ratio ≥30 mg/g. At molecular level MetS is marked by a proinflammatory state and increased oxidative stress leading to various pathophysiological changes causing endothelial dysfunction and a hypercoagulable state. Because the kidney is a highly vascularized organ, it is especially susceptible for those microvascular changes. Therefore, the MetS and its individual components are associated with the premature development, acceleration, and progression of chronic kidney disease. Therefore, it is becoming increasingly important to elucidate the underlying mechanisms of MetS-associated chronic kidney disease in order to develop new strategies for preventing and slowing the progression of renal disease. In this review, we will elucidate (i) the renal structural, hemodynamic, and metabolic changes that occur in obesity and obesity-related kidney injury; (ii) the clinicopathological characteristics of obesity-related kidney injury, primarily focusing on obesity-associated glomerulopathy; (iii) the potential additional factors or predisposing factors that may turn patients more susceptible to renal structural or functional compensatory failure and subsequent injury.

Acute kidney injury in diabetic patients: A narrative review

Diabetes mellitus (DM) is the most common cause of chronic kidney disease, which leads to end-stage renal failure worldwide. Glomerular damage, renal arteriosclerosis, and atherosclerosis are the contributing factors in diabetic patients, leading to the progression of kidney damage. Diabetes is a distinct risk factor for acute kidney injury (AKI) and AKI is associated with faster advancement of renal disease in patients with diabetes. The long-term consequences of AKI include the development of end-stage renal disease, higher cardiovascular and cerebral events, poor quality of life, and high morbidity and mortality. In general, not many studies discussed extensively "AKI in DM." Moreover, articles addressing this topic are scarce. It is also important to know the cause of AKI in diabetic patients so that timely intervention and preventive strategies can be implemented to decrease kidney injury. Aim of this review article is to address the epidemiology of AKI, its risk factors, different pathophysiological mechanisms, how AKI differs between diabetic and nondiabetic patients and its preventive and therapeutic implications in diabetics. The increasing occurrence and prevalence of AKI and DM, as well as other pertinent issues, motivated us to address this topic.

Repurposing antidiabetic drugs for rheumatoid arthritis: results from a two-sample Mendelian randomization study

Despite increasing therapeutic options to treat rheumatoid arthritis (RA), many patients fail to reach treatment targets. The use of antidiabetic drugs like thiazolidinediones has been associated with lower RA risk. We aimed to explore the repurposing potential of antidiabetic drugs in RA prevention by assessing associations between genetic variation in antidiabetic drug target genes and RA using Mendelian randomization (MR). A two-sample MR design was used to estimate the association between the antidiabetic drug and RA risk using summary statistics from genome-wide association studies (GWAS). We selected independent genetic variants from the gene(s) that encode the target protein(s) of the investigated antidiabetic drug as instruments. We extracted the associations of instruments with blood glucose concentration and RA from the UK Biobank and a GWAS meta-analysis of clinically diagnosed RA, respectively. The effect of genetic variation in the drug target(s) on RA risk was estimated by the Wald ratio test or inverse-variance weighted method. Insulin and its analogues, thiazolidinediones, and sulfonylureas had valid genetic instruments (n = 1, 1, and 2, respectively). Genetic variation in thiazolidinedione target (gene: PPARG) was inversely associated with RA risk (odds ratio [OR] 0.38 per 0.1mmol/L glucose lowering, 95% confidence interval [CI] 0.20-0.73). Corresponding ORs (95%CIs) were 0.83 (0.44-1.55) for genetic variation in the targets of insulin and its analogues (gene: INSR), and 1.12 (0.83, 1.49) 1.25 (0.78-2.00) for genetic variation in the sulfonylurea targets (gene: ABCC8 and KCNJ11). In conclusion, genetic variation in the thiazolidinedione target is associated with a lower RA risk. The underlying mechanisms warrant further exploration.

Pioglitazone enhances proteinuria reduction in complicated pediatric nephrotic syndrome

BACKGROUND

Nephrotic syndrome (NS) is a common pediatric kidney disease, yet current treatments for complicated NS are only partially effective and have significant toxicity. There is no Food and Drug Administration (FDA)- or European Medicines Agency (EMA)-approved safe and effective treatment for NS. Thiazolidinediones (TZDs) have been shown to reduce proteinuria in both diabetic and non-diabetic kidney disease and in preclinical studies to directly protect podocytes from injury and reduce proteinuria. Here, we report on the potential utility of the addition of the TZD pioglitazone (PIO) to enhance proteinuria reduction in 8 children and young adults with steroid dependent NS and steroid resistant NS.

METHODS

Clinical data were analyzed in comparable time periods before and after the addition of PIO to their medical regimens. Eight NS patients with minimal change NS (n = 2), focal segmental glomerulosclerosis (FSGS) (n = 4), or collapsing FSGS (n = 2) were evaluated.

RESULTS

Prior to PIO initiation, all children and young adults had already received multiple immunosuppressive medications (mean = 3.75). Five of eight patients (63%; "Responders") had notable proteinuria reduction within 1 month of PIO initiation (62% reduction; P = 0.04) and normalization within 6 months (97% reduction; P = 0.04). PIO-related benefits among the responders included notable increases in serum albumin (2.5 to 3.7 g/dl; P = 0.08), dramatic reductions in hospitalizations for IV albumin infusions and diuresis (11 to 0; P < 0.01), and considerable reduction in total immunosuppression (43% reduction; P > 0.1). Importantly, no patients experienced any adverse events attributable to PIO during a total of 136 patient-months of treatment.

CONCLUSIONS

While confirmatory safety and efficacy studies are needed, these findings suggest pioglitazone (a non-immunosuppressive drug) may be useful to enhance proteinuria reduction in some children and young adults with complicated NS. A higher resolution version of the Graphical abstract is available as Supplementary information.

Peroxisome proliferator-activated receptor ɣ agonist mediated inhibition of heparanase expression reduces proteinuria

BACKGROUND

Proteinuria is associated with many glomerular diseases and a risk factor for the progression to renal failure. We previously showed that heparanase (HPSE) is essential for the development of proteinuria, whereas peroxisome proliferator-activated receptor ɣ (PPARɣ) agonists can ameliorate proteinuria. Since a recent study showed that PPARɣ regulates HPSE expression in liver cancer cells, we hypothesized that PPARɣ agonists exert their reno-protective effect by inhibiting glomerular HPSE expression.

METHODS

Regulation of HPSE by PPARɣ was assessed in the adriamycin nephropathy rat model, and cultured glomerular endothelial cells and podocytes. Analyses included immunofluorescence staining, real-time PCR, heparanase activity assay and transendothelial albumin passage assay. Direct binding of PPARɣ to the HPSE promoter was evaluated by the luciferase reporter assay and chromatin immunoprecipitation assay. Furthermore, HPSE activity was assessed in 38 type 2 diabetes mellitus (T2DM) patients before and after 16/24 weeks treatment with the PPARɣ agonist pioglitazone.

FINDINGS

Adriamycin-exposed rats developed proteinuria, an increased cortical HPSE and decreased heparan sulfate (HS) expression, which was ameliorated by treatment with pioglitazone. In line, the PPARɣ antagonist GW9662 increased cortical HPSE and decreased HS expression, accompanied with proteinuria in healthy rats, as previously shown. In vitro, GW9662 induced HPSE expression in both endothelial cells and podocytes, and increased transendothelial albumin passage in a HPSE-dependent manner. Pioglitazone normalized HPSE expression in adriamycin-injured human endothelial cells and mouse podocytes, and adriamycin-induced transendothelial albumin passage was reduced as well. Importantly, we demonstrated a regulatory effect of PPARɣ on HPSE promoter activity and direct PPARy binding to the HPSE promoter region. Plasma HPSE activity of T2DM patients treated with pioglitazone for 16/24 weeks was related to their hemoglobin A1c and showed a moderate, near significant correlation with plasma creatinine levels.

INTERPRETATION

PPARɣ-mediated regulation of HPSE expression appears an additional mechanism explaining the anti-proteinuric and renoprotective effects of thiazolidinediones in clinical practice.

FUNDING

This study was financially supported by the Dutch Kidney Foundation, by grants 15OI36, 13OKS023 and 15OP13. Consortium grant LSHM16058-SGF (GLYCOTREAT; a collaboration project financed by the PPP allowance made available by Top Sector Life Sciences & Health to the Dutch Kidney Foundation to stimulate public-private partnerships).

PPARG agonist pioglitazone influences diurnal kidney medulla mRNA expression of core clock, inflammation-, and metabolism-related genes disrupted by reverse feeding in mice

This study examined the influence of PPARG activation by pioglitazone (PG) on the mRNA of core clock, inflammation- and metabolism-related genes in the mouse kidney medulla as well as urinary sodium/potassium excretion rhythms disrupted by reverse feeding. Mice were assigned to daytime feeding and nighttime feeding groups. PG 20 mg/kg was administered at 7 am or 7 pm. On day 8 of the feeding intervention, mice were killed at noon and midnight. Kidney medulla expression of Arntl, Clock, Nr1d1, Cry1, Cry2, Per1, Per2, Nfe2l2, Pparg, and Scnn1g was determined by qRT PCR. We measured urinary K⁺ , Na⁺ , urine volume, food, and H₂ O intake. The reverse feeding uncoupled the peripheral clock gene rhythm in mouse kidney tissues. It was accompanied by a decreased expression of Nfe2l2 and Pparg as well as an increased expression of Rela and Scnn1g. These changes in gene expressions concurred with an increase in urinary Na⁺ , K⁺ , water excretion, microcirculation disorders, and cell loss, especially in distal tubules. PG induced the restoration of diurnal core clock gene expression as well as Nfe2l2, Pparg, Scnn1g mRNA, and decreased Rela expressions, stimulating Na⁺ reabsorption and inhibiting K⁺ excretion. PG intake at 7 pm was more effective than at 7 am.

An Update on the Current and Emerging Use of Thiazolidinediones for Type 2 Diabetes

Guidelines have increasingly stressed the concept that adequate glycemic control is required to prevent or decrease the macro- and microvascular complications of type 2 diabetes mellitus (T2DM). PPAR-gamma agonists (“glitazones”) are no longer prioritized due to their effects on heart failure. However, the association between these drugs and innovative therapies could be a valuable tool to attenuate the risk factors of the metabolic syndrome. Glitazones are used for the treatment of diabetes and associated comorbidities. There is substantial scientific evidence demonstrating the effect of glitazones at a cardiometabolic level, as well as on hematological and neurological pathologies that point to their usefulness. The use of glitazones has always been controversial both for the type of patients who must take these drugs and for the side effects associated with them. Unfortunately, the recent guidelines do not include them among the preferred drugs for the treatment of hyperglycemia and rosiglitazone is out of the market in many countries due to an adverse cardiovascular risk profile. Even though real-life studies have proven otherwise, and their pleiotropic effects have been highlighted, they have been unable to achieve primacy in the choice of antihyperglycemic drugs. It would be appropriate to demonstrate the usefulness of pioglitazone and its therapeutic benefit with further cardiovascular safety studies.

Rosiglitazone Alleviates Contrast-Induced Acute Kidney Injury in Rats via the PPARγ/NLRP3 Signaling Pathway

Background

This study investigated the effect and mechanism of rosiglitazone on a rat model with contrast-induced acute kidney injury (CI-AKI).

Materials and Methods

The CI-AKI rat model was established from Sprague Dawley rats by furosemide injection (10 ml/kg) to the caudal vein followed by iohexol (11.7 ml/kg). The experimental grouping was randomly allocated into control, model, rosiglitazone, and T0070907 groups. Blood samples were collected from the abdominal aorta. Serum creatinine, urea nitrogen, MDA, and SOD contents were detected by biochemical analysis. TNF-α and IL-10 expression was detected by ELISA. Urine creatinine and urine protein were measured following 24-h urine biochemistry testing. Cell pathology and apoptosis were detected by H&E and TUNEL staining, respectively. PPARγ, NLRP3, eNOS, and caspase-3 mRNA expression were detected by qPCR. Caspase-3 and NLRP3 expression were detected by immunohistochemistry.

Results

The CI-AKI rat model was successfully established because the results showed that compared with control, serum creatinine, urea nitrogen, MDA, SOD, TNF-α, and IL-10, urine creatinine and urine protein levels were significantly increased in the model group, indicating AKI, but was significantly decreased with rosiglitazone treatment, indicating recovery from injury, while opposite results were obtained with SOD. Apoptosis rate was significantly increased in the model group and significantly decreased with rosiglitazone treatment. NLRP3 and eNOS increased significantly in the model group and decreased significantly with rosiglitazone treatment, while opposite results were obtained with PPARγ. NLRP3 and caspase-3 protein expression was significantly increased in the model group and significantly decreased with rosiglitazone treatment.

Conclusion

Rosiglitazone could alleviate acute renal injury in the CI-AKI rat model by regulating the PPARγ/NLRP3 signaling pathway and should be further investigated as a potential treatment in clinical studies.

Use of Glucose-Lowering Agents in Diabetes and CKD

Diabetes is the most common cause of kidney failure worldwide. Patients with diabetes and chronic kidney disease (CKD) are also at markedly higher risk of cardiovascular disease, particularly heart failure (HF), and death. Through the processes of gluconeogenesis and glucose reabsorption, the kidney plays a central role in glucose homeostasis. Insulin resistance is an early alteration observed in CKD, worsened by the frequent presence of hypertension, obesity, and ongoing chronic inflammation, and oxidative stress. Management of diabetes in moderate to severe CKD warrants special consideration because of changes in glucose and insulin homeostasis and altered metabolism of glucose-lowering therapies. Kidney failure and initiation of kidney replacement therapy by dialysis adds to management complexity by further limiting therapeutic options, and predisposing individuals to hypoglycemia and hyperglycemia. Glycemic goals should be individualized, considering CKD severity, presence of macrovascular and microvascular complications, and life expectancy. A general hemoglobin A1c (HbA1c) goal of approximately 7% may be appropriate in earlier stages of CKD, with more relaxed targets often appropriate in later stages. Use of sodium glucose cotransporter2 (SGLT2) inhibitors and glucagon like peptide-1 receptor agonists (GLP-1RAs) meaningfully improves kidney and heart outcomes for patients with diabetes and CKD, irrespective of HbA1c targets, and are now part of guideline-directed medical therapy in this high-risk population. Delivery of optimal care for patients with diabetes and CKD will require collaboration across health care specialties and disciplines.

Obesity-related glomerulopathy: Current approaches and future perspectives

Obesity-related glomerulopathy (ORG) is a silent comorbidity which is increasing in incidence as the obesity epidemic escalates. ORG is associated with serious health consequences including chronic kidney disease, end-stage renal disease (ESRD), and increased mortality. Although the pathogenic mechanisms involved in the development of ORG are not fully understood, glomerular hemodynamic changes, renin-angiotensin-aldosterone system (RAAS) overactivation, insulin-resistance, inflammation and ectopic lipid accumulation seem to play a major role. Despite albuminuria being commonly used for the non-invasive evaluation of ORG, promising biomarkers of early kidney injury that are emerging, as well as new approaches with proteomics and metabolomics, might permit an earlier diagnosis of this disease. In addition, the assessment of ectopic kidney fat by renal imaging could be a useful tool to detect and evaluate the progression of ORG. Weight loss interventions appear to be effective in ORG, although large-scale trials are needed. RAAS blockade has a renoprotective effect in patients with ORG, but even so, a significant proportion of patients with ORG will eventually progress to ESRD despite therapeutic efforts. It is noteworthy that certain antidiabetic agents such as sodium-glucose cotransporter 2 inhibitors (SGLT2i) or glucagon-like peptide-1 receptor agonists (GLP-1 RAs) could be useful in the treatment of ORG through different pleiotropic effects. In this article, we review current approaches and future perspectives in the care and treatment of ORG.

Inflammation and Oxidative Stress in Chronic Kidney Disease and Dialysis Patients

Significance: Chronic kidney disease (CKD) can be regarded as a burden of lifestyle disease that shares common underpinning features and risk factors with the aging process; it is a complex constituted by several adverse components, including chronic inflammation, oxidative stress, early vascular aging, and cellular senescence. Recent Advances: A systemic approach to tackle CKD, based on mitigating the associated inflammatory, cell stress, and damage processes, has the potential to attenuate the effects of CKD, but it also preempts the development and progression of associated morbidities. In effect, this will enhance health span and compress the period of morbidity. Pharmacological, nutritional, and potentially lifestyle-based interventions are promising therapeutic avenues to achieve such a goal. Critical Issues: In the present review, currents concepts of inflammation and oxidative damage as key patho-mechanisms in CKD are addressed. In particular, potential beneficial but also adverse effects of different systemic interventions in patients with CKD are discussed. Future Directions: Senotherapeutics, the nuclear factor erythroid 2-related factor 2-kelch-like ECH-associated protein 1 (NRF2-KEAP1) signaling pathway, the endocrine klotho axis, inhibitors of the sodium-glucose cotransporter 2 (SGLT2), and live bio-therapeutics have the potential to reduce the burden of CKD and improve quality of life, as well as morbidity and mortality, in this fragile high-risk patient group. Antioxid. Redox Signal. 35, 1426-1448.

Protocol for a preclinical systematic review and meta-analysis of pharmacological targeting of peroxisome proliferator-activated receptors in experimental renal injury

INTRODUCTION

Impaired lipid metabolism in the renal tubule plays a prominent role in the progression of renal fibrosis following acute kidney injury (AKI) and in chronic kidney disease (CKD). Peroxisome proliferator-activated receptors (PPARs) are promising druggable targets to mitigate renal fibrosis by redirecting metabolism, including restoration of fatty acid oxidation (FAO) capacity. We aim to synthesise evidence from preclinical studies of pharmacological PPAR targeting in experimental renal injury, and inform the design of future studies evaluating PPAR-mediated restoration of FAO in AKI and CKD.

METHODS AND ANALYSIS

Studies reporting on the impact of pharmacological PPAR modulation in animal models of renal injury will be collected from MEDLINE (Ovid), Embase and Web of Science databases. Predefined eligibility criteria will exclude studies testing medications which are not specific ligands of one or more PPARs and studies involving multimodal pharmacological treatment. The Systematic Review Centre for Laboratory Animal Experimentation risk of bias tool and Collaborative Approach to Meta-Analysis and Review of Animal Experimental Studies checklist will be used to assess quality of the included studies. Data extraction will be followed by a narrative synthesis of the data and meta-analysis where feasible. Analysis will be performed separately for AKI, CKD and renal transplant models. Subgroup analyses will be performed based on study design characteristics, PPAR isotype(s) targeted, and classes of PPAR-targeting medications used. Risk of publication bias will be assessed using funnel plotting, Egger's regression and trim-and-fill analysis.

ETHICS AND DISSEMINATION

Ethical approval is not required. Findings will be published in a peer-reviewed journal and presented at scientific meetings.

PROSPERO REGISTRATION NUMBER

CRD42021265550.

PPARγ and TGFβ-Major Regulators of Metabolism, Inflammation, and Fibrosis in the Lungs and Kidneys

Peroxisome proliferator-activated receptor gamma (PPARγ) is a type II nuclear receptor, initially recognized in adipose tissue for its role in fatty acid storage and glucose metabolism. It promotes lipid uptake and adipogenesis by increasing insulin sensitivity and adiponectin release. Later, PPARγ was implicated in cardiac development and in critical conditions such as pulmonary arterial hypertension (PAH) and kidney failure. Recently, a cluster of different papers linked PPARγ signaling with another superfamily, the transforming growth factor beta (TGFβ), and its receptors, all of which play a major role in PAH and kidney failure. TGFβ is a multifunctional cytokine that drives inflammation, fibrosis, and cell differentiation while PPARγ activation reverses these adverse events in many models. Such opposite biological effects emphasize the delicate balance and complex crosstalk between PPARγ and TGFβ. Based on solid experimental and clinical evidence, the present review summarizes connections and their implications for PAH and kidney failure, highlighting the similarities and differences between lung and kidney mechanisms as well as discussing the therapeutic potential of PPARγ agonist pioglitazone.

Acute Kidney Injury in Pediatric Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a common complication of type 1 and 2 diabetes and often presents during adolescence and young adulthood. Given the growing incidence of both type 1 and type 2 diabetes in children and adolescents, DKD represents a significant public health problem. Acute kidney injury (AKI) in youth with diabetes is strongly associated with risk of DKD development. This review will summarize the epidemiology and pathophysiology of AKI in children with diabetes, the relationship between AKI and DKD, and the potential therapeutic interventions. Finally, we will appraise the impact of the recent COVID-19 infection pandemic on AKI in children with diabetes.

Comparative Efficacy of Lobeglitazone Versus Pioglitazone on Albuminuria in Patients with Type 2 Diabetes Mellitus

INTRODUCTION

The aim of this analysis was to evaluate the efficacy of lobeglitazone on albuminuria at 24 weeks of follow-up in patients with type 2 diabetes mellitus (T2DM) compared with pioglitazone using data from a randomized, double-blinded phase III trial.

METHODS

In the phase III trial, patients who were inadequately controlled with metformin received 0.5 mg of lobeglitazone or 15 mg of pioglitazone for 24 weeks. Post hoc, exploratory analysis was used to investigate mean changes from baseline in the urine albumin-creatinine ratio (UACR) between the lobeglitazone (N = 104) and pioglitazone (N = 101) treatment groups.

RESULTS

After 24 weeks of treatment, UACR was slightly decreased in the lobeglitazone group (- 4.3 mg/g creatinine [Cr]) compared to baseline and slightly increased in the pioglitazone group (5.2 mg/g Cr), with no change in the estimated glomerular filtration rate in either group; this difference was not statistically significant (P = 0.476). The incidence of new-onset microalbuminuria (2.4%) and the progression of albuminuria by > 1 stage (2.9%) in the lobeglitazone group were lower than the respective values in the pioglitazone group (6.8 and 6.1%, respectively). Of the patients in the lobeglitazone group, 50% exhibited regression to normoalbuminuria, compared to 39.3% of the patients in the pioglitazone. In subjects in the lobeglitazone group with micro- and macroalbuminuria, UACR tended to be more decreased and HbA1c was more reduced compared to those with normoalbuminuria (P = 0.014).

CONCLUSION

Lobeglitazone had a tendency to improve albuminuria in patients with T2DM and had comparable effects on albuminuria as pioglitazone which has demonstrated beneficial effects.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT01106131.

Nuclear receptors in the kidney during health and disease

Over the last 30 years, nuclear receptors (NRs) have been increasingly recognized as key modulators of systemic homeostasis and as contributing factors in many diseases. In the kidney, NRs play numerous important roles in maintaining homeostasis-many of which continue to be unraveled. As "master regulators", these important transcription factors integrate and coordinate many renal processes such as circadian responses, lipid metabolism, fatty acid oxidation, glucose handling, and inflammatory responses. The use of recently-developed genetic tools and small molecule modulators have allowed for detailed studies of how renal NRs contribute to kidney homeostasis. Importantly, while NRs are intimately involved in proper kidney function, they are also implicated in a variety of renal diseases such as diabetes, acute kidney injury, and other conditions such as aging. In the last 10 years, our understanding of renal disease etiology and progression has been greatly shaped by knowledge regarding how NRs are dysregulated in these conditions. Importantly, NRs have also become attractive therapeutic targets for attenuation of renal diseases, and their modulation for this purpose has been the subject of intense investigation. Here, we review the role in health and disease of six key renal NRs including the peroxisome proliferator-activated receptors (PPAR), estrogen-related receptors (ERR), the farnesoid X receptors (FXR), estrogen receptors (ER), liver X receptors (LXR), and vitamin D receptors (VDR) with an emphasis on recent findings over the last decade. These NRs have generated a wealth of data over the last 10 years that demonstrate their crucial role in maintaining normal renal homeostasis as well as their capacity to modulate disease progression.

Ramipril blunts glycerol-induced acute renal failure in rats through its antiapoptosis, anti-inflammatory, antioxidant, and renin-inhibiting properties

OBJECTIVES

Acute kidney injury (AKI) is a malady with a sudden onset resulting in buildup of waste matters in the body, but a specific cure hasn't been found as a lasting solution to AKI. In this study, ramipril was evaluated for its potential therapy in glycerol-induced AKI in rats.

METHODS

Twenty animals were divided into four groups of five animals each. Group I was the control while group II was given glycerol on day 8 only, groups III and IV were administered with pioglitazone (reference drug) and ramipril for seven days respectively and on day 8 received glycerol. On the ninth day, blood and tissue samples were taken to assay for serum indicators of oxidative damage, enzymatic and nonenzymatic antioxidants, and creatinine and blood urea nitrogen. Animals were sacrificed thereafter; kidney was harvested for histological and immunohistochemical analysis. Expressions of caspase 3, renin receptor, NK-KB, and KIM-1 were carried out.

RESULTS

Ramipril significantly inhibited indicators of oxidative damage while also significantly increasing levels of enzymatic and nonenzymatic antioxidant markers. These drugs also significantly lowered the levels of creatinine and blood urea nitrogen. Histology also indicated that while there were massive infiltration of leucocytes and congestion of the kidney in toxicant group, the ramipril-treated group showed a milder condition. In immunohistochemistry, the two drugs significantly inhibited the expressions of the four proteins, which were highly expressed in the toxicant group.

CONCLUSIONS

The study showed that ramipril and pioglitazone have nephroprotective effect and thus have the ability to blunt AKI through their anti-inflammatory, antiapoptosis, antirenin, and antioxidant properties.

Treatment with a PPAR-γ Agonist Protects Against Hyperuricemic Nephropathy in a Rat Model

Purpose

Hyperuricemia is an independent risk factor for renal damage and can promote the progression of chronic kidney disease (CKD). In the present study, we employ a rat model to investigate the effects of rosiglitazone (RGTZ), a peroxisome proliferator-activated receptor-gamma agonist, on the development of hyperuricemic nephropathy (HN), and we elucidate the mechanisms involved.

Methods

An HN rat model was established by oral administration of a mixture of adenine and potassium oxonate daily for 3 weeks. Twenty-four rats were divided into 4 groups: sham treatment, sham treatment plus RGTZ, HN, and HN treated with RGTZ.

Results

Administration of RGTZ effectively preserved renal function, decreased urine microalbumin, and inhibited interstitial fibrosis and macrophage infiltration in a rat HN model. RGTZ treatment also inhibited TGF-β and NF-κB pathway activation, decreased expression of fibronectin, collagen I, α-SMA, vimentin, MCP-1, RANTES, TNF-α, and IL-1β, and increased E-cadherin expression in the kidneys of HN rats. Furthermore, RGTZ treatment preserved expression of OAT1 and OAT3 in the kidney of HN rats.

Conclusion

RGTZ attenuates the progression of HN through inhibiting TGF-β signaling, suppressing epithelial-to-mesenchymal transition, reducing inflammation, and lowering serum uric acid levels by preserving expression of urate transporters.

Beneficial Effects of Isoflavones in the Kidney of Obese Rats Are Mediated by PPAR-Gamma Expression

Several studies have demonstrated an important association between altered lipid metabolism and the development of kidney injury because of a high-fat diet. Fructose is also closely associated with renal injury. We opted for a combination of fructose and saturated fats in a diet (DH) that is a model known to induce renal damage in order to evaluate whether soy isoflavones could have promising use in the treatment of renal alterations. After two months of ingestion, there was an expansion of visceral fat, which was associated with long-term metabolic disorders, such as sustained hyperglycemia, insulin resistance, polyuria, dyslipidemia, and hypertension. Additionally, we found a decrease in renal blood flow and an increase in renal vascular resistance. Biochemical markers of chronic kidney disease were detected; there was an infiltration of inflammatory cells with an elevated expression of proinflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-6, and IL-1β), the activation of the renin–angiotensin system, and oxidative/nitrosative stress. Notably, in rats exposed to the DH diet for 120 days, the concomitant treatment with isoflavones after 60 days was able to revert metabolic parameters, renal alterations, and oxidative/nitrosative stress. The beneficial effects of isoflavones in the kidney of the obese rats were found to be mediated by expression of peroxisome proliferator-activated receptor gamma (PPAR-γ).

Uric acid stone disease: lessons from recent human physiologic studies

PURPOSE OF REVIEW

An overly acidic urine resulting in supersaturation of urine with respect to uric acid is the major mechanism responsible for uric acid nephrolithiasis. The present review summarizes findings from recent human physiologic studies examining the pathophysiology and reversibility of low urine pH in uric acid stone formers.

RECENT FINDINGS

Epidemiologic and metabolic studies have confirmed an increase in the prevalence of uric acid nephrolithiasis and reported its association with several features of the metabolic syndrome including dyslipidemia, hyperglycemia, hepatic steatosis, and greater visceral adiposity. Physiologic studies in uric acid stone formers have identified diet-independent excessive net acid excretion and concomitant reduction in urinary buffering from impaired renal ammoniagenesis as the two causes underlying the greater aciduria. Administration of the insulin sensitizer pioglitazone to uric acid stone formers reduced the acid load presented to the kidney and enhanced ammoniagenesis and ammonium excretion, resulting in significantly higher urine pH.

SUMMARY

Recent human physiologic studies have identified greater acid excretion and reduced urinary buffering by ammonia as two culprits of aciduria in uric acid nephrolithiasis that can be reversed by pioglitazone, raising new questions regarding the origin of the aciduria and opening the door to pathophysiology-based treatment of uric acid stones.

Pioglitazone for the Primary and Secondary Prevention of Cardiovascular and Renal Outcomes in Patients with or at High Risk of Type 2 Diabetes Mellitus: A Meta-Analysis

CONTEXT

The goal of the meta-analysis was to evaluate the effect of pioglitazone on the primary and secondary prevention of cardiovascular diseases (CVDs) and renal adverse events in patients with or at high risk of type 2 diabetes mellitus (T2DM).

DESIGN

Randomized controlled trials (RCTs) comparing pioglitazone with any control were identified through PubMed, Embase, and the Cochrane Library. Cardiovascular outcomes included major adverse cardiovascular events (MACEs, defined as the composite of nonfatal myocardial infarction, nonfatal stroke, and cardiovascular death), hospitalization for heart failure, and all-cause mortality. Renal outcomes included change in urinary albumin to creatinine ratio and 24-hour urinary protein excretion. Weighted mean difference (WMD) and risk ratio (RR) with 95% confidence intervals (CIs) were pooled.

RESULTS

A total of 26 studies with 19 645 participants were enrolled. Pioglitazone reduced the risk of MACE (RR, 0.8 [95% CI, 0.7-0.9]), with benefit only seen in patients with a history of established CVDs (0.8 [0.7-0.9]) and not in those without (1.0 [0.7-1.3]). Regarding the individual components, pioglitazone reduced the risk of nonfatal myocardial infarction (0.8 [0.6-1.0]) and nonfatal stroke (0.8 [0.7-0.9]), which was confined to patients with a history of established CVDs, whereas no treatment effect was found on cardiovascular death (1.0 [0.7-1.2]) regardless of the presence of established CVDs. Pioglitazone increased the risk of hospitalization for heart failure (1.3 [1.1-1.6]) and had no treatment effect on all-cause mortality (1.0 [0.8-1.1]). Pioglitazone reduced albuminuria by 18.5% (WMD 18.5% [95% CI, 21.1-16.0]), with a similar benefit in patients with different renal function categories.

CONCLUSIONS

Pioglitazone should be considered in patients with or at high risk of T2DM for the prevention of cardiovascular endpoints, especially in those with a history of established CVD who might benefit the most. Robust reductions in progression of renal disease are seen regardless of baseline renal function degree.

Recent Progress on Lipid Intake and Chronic Kidney Disease

The incidence of chronic kidney disease (CKD) is associated with major abnormalities in circulating lipoproteins and renal lipid metabolism. This article elaborates on the mechanisms of CKD and lipid uptake abnormalities. The viewpoint we supported is that lipid abnormalities directly cause CKD, resulting in forming a vicious cycle. On the theoretical and experiment fronts, this inference has been verified by elaborately elucidating the role of lipid intake and accumulation as well as their influences on CKD. Taken together, these findings suggest that further understanding of lipid metabolism in CKD may lead to novel therapeutic approaches.

Effects of 10-week combined training on lipid metabolic regulatory hormones and metabolic syndrome index according to exercise dose in obese male college students

To analyze the effects of 10-week combined training (aerobic and resistance exercise) in three groups that were divided according to the total exercise dose per week and elucidate its effects on insulin and leptin (lipid metabolic regulatory hormones) and metabolic syndrome index. We included 24 obese male college students with body mass index ≥25 kg/m². Each 8 subjects were randomly assigned according to the total exercise dose per week into the 150-, 270-, and 450-min/wk exercise groups, which performed 50-, 90-, and 90-min exercise per day for 3, 3, and 5 times a week, respectively. To maintain a constant level of exercise intensity, aerobic exercises were performed while maintaining 60%–70% of the maximal heart rate and resistance exercise at 60%–70% load of the initial 1 repetition maximum; 1 repetition maximum was measured every 2 weeks. Training effects on lipid metabolic regulatory hormones in the blood and metabolic syndrome index according to the total exercise dose/week were analyzed. Insulin and leptin levels decreased in the 270- and 450-min/wk exercise groups but no significant difference was observed in the 150-min/wk exercise group. Waist circumference showed a significant decrease in all groups, but blood pressure did not change. Fasting blood glucose levels significantly decreased in the 270- and 450-min/wk exercise groups. Triglyceride and high-density lipoprotein-cholesterol levels significantly decreased in the 450-min/wk exercise group. Combined training with an appropriate total exercise dose may prevent diseases caused by obesity by improving energy expenditure and insulin sensitivity and triggering positive changes in glucose and lipid metabolism.

Pioglitazone attenuates kidney injury in an experimental model of gentamicin-induced nephrotoxicity in rats

Gentamicin, belonging to the aminoglycosides, possesses the greatest nephrotoxic effect of all other antibiotics from this group. On the other hand, pioglitazone, which represents peroxisome proliferator-activated receptor γ (PPARγ) agonist recently showed antiinflamatory, antioxidative effects, amelioration of endothelial dysfunction etc. Therefore, the goal of our study was to investigate the effects of pioglitazone on kidney injury in an experimental model of gentamicin-induced nephrotoxicity in rats. These effects were observed by following values of biochemical (serum urea and creatinine) parametars, total histological kidney score, urine level of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) as well as parametars of oxidative stress (malondialdehyde, superoxide dismutase, catalase, total oxidant status, total antioxidant status, oxidative stress index and advanced oxidation protein products). It seems that pioglitazone protects the injured rat kidney in a U-shaped manner. Medium dose of pioglitazone (1 mg/kg, i.p.) was protective regarding biochemical (serum urea and creatinine), total histological score and the values of kidney injury molecule-1 (KIM-1) (P < 0.05 vs. control group, i.e. rats injected with gentamicin only). This finding could be of great importance for the wider use of aminoglycosides, with therapy that would reduce the occurrence of serious adverse effects, such as nephrotoxicity and acute renal failure.

Type 2 diabetes treatment and progression of chronic kidney disease in Italian family practice

AIMS

Progressive chronic kidney disease represents a dreadful complication of type 2 diabetes mellitus (T2DM). We tested the pattern of use and the renal effects of old glucose-lowering drugs in T2DM patients cared for by Italian general practitioners (GPs).

METHODS

Data of 2606 T2DM patients were extracted from the databases of GPs, who do not have access to the most recent glucose-lowering drugs in Italy. The rate of kidney function decline was calculated by CKD-EPI_cr, based on two consecutive creatinine values.

RESULTS

Metformin was used in 55% of cases, either alone or with sulfonylureas/repaglinide, across the whole spectrum of CKD (from 66% in stage G1 to only 8% in G4). Sulfonylurea use peaked at 21-22% in stage G2-G3a, whereas repaglinide use significantly increased from 8% in G1 to 22% in G4. The median rate of CKD decline was - 1.64 mL/min/1.73 m² per year; it was higher in G1 (- 3.22 per year) and progressively lower with CKD severity. 826 cases (31.7%) were classified as fast progressors (eGFR decline more negative than - 5 mL/min/1.73 m² per year). The risk of fast progressing CKD was associated with increasing BMI, albuminuria, and sulfonylurea use, alone (OR, 1.47; 95% confidence interval, 1.16-1.85), or in association with metformin (OR, 1.40; 95% CI 1.04-1.88). No associations were demonstrated for metformin, cardiovascular and lipid lowering drug use.

CONCLUSION

In the setting of Italian family practice, sulfonylurea use is associated with progressive CKD in patients with T2DM. Metformin, at doses progressively reduced according to CKD stages, as recommended by guidelines, is not associated with fast progression.

Protective effect of rosiglitazone on chronic renal allograft dysfunction in rats

BACKGROUND

Chronic renal allograft dysfunction (CRAD) is the main condition affecting the long-term survival of renal allografts. Rosiglitazone, which is a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, has been shown to exert antifibrotic and anti-inflammatory effects on some renal diseases. The present paper investigates the effect of rosiglitazone on CRAD using a murine model.

METHODS

The CRAD group received classical orthotopic F344-Lewis kidney transplantation. The treatment group was treated with rosiglitazone for 12 weeks following renal transplantation. The control subjects were uninephrectomized F344 and Lewis rats. Twelve weeks after the operation, the rats were harvested for renal function, histological, immunohistochemical and molecular biological analyses.

RESULTS

Rosiglitazone treatment effectively decreased urine protein excretion and preserved renal function in the CRAD rats. Administration of rosiglitazone also inhibited interstitial fibrosis and macrophage infiltration in the CRAD rat kidneys. Furthermore, rosiglitazone treatment inhibited TGF-β and NF-κB pathway activation, decreased collagen I, collagen IV, α-SMA, MCP-1, ICAM-1, TNF-α, and IL-1β expression, and increased E-cadherin expression in renal allograft tissues from the CRAD rats.

CONCLUSIONS

Rosiglitazone successfully attenuates the development of CRAD via inhibition of TGF-β signaling, the renal tubular epithelial-to-mesenchymal transition (EMT), and inflammation.

The clinical efficacy of angiotensin II type1 receptor blockers on inflammatory markers in patients with hypertension: a multicenter randomized-controlled trial; MUSCAT-3 study

Purpose: The purpose of present study was to evaluate the clinical efficacy of irbesartan on the anti-inflammatory and anti-oxidative stress effect in patients with hypertension compared to other ARBs. Further, we assessed the effect of the ARBs on kidney function and urinary albumin excretion. Methods: Eighty-five outpatients with hypertension who took an ARB except irbesartan more than 3 months were assigned into two groups, one continued the same ARB and the other switched the ARB to irbesartan for 6 months. Results: Although blood pressures were equally controlled (continue group: 148 ± 2/79 ± 2 mmHg to 131 ± 2/74 ± 2 mmHg; switch group: 152 ± 2/81 ± 2 mmHg to 132 ± 2/74 ± 2 mmHg; p < 0.001 each), the inflammatory markers (hsCRP, PTX3, MCP-1) and oxidative stress marker (MDA-LDL) did not change after 6 months in both groups. Urinary albumin excretion was significantly reduced only in the switch group without renal function deterioration (switch group 292.4 ± 857.9 mg/gCr to 250.6 ± 906.5 mg/gCr, p = 0.012). Conclusion: These results provide knowledge of the characteristics of irbesartan, suggesting appropriate choice of ARBs in the treatment for hypertension should be considered.

Effects of glucose-lowering agents on surrogate endpoints and hard clinical renal outcomes in patients with type 2 diabetes

Diabetic kidney disease (DKD) represents an enormous burden in patients with type 2 diabetes mellitus (T2DM). Preclinical studies using most glucose-lowering agents have suggested renal-protective effects, but the proposed mechanisms of renoprotection have yet to be defined, and the promising results from experimental studies remain to be translated into human clinical findings to improve the prognosis of patients at risk of DKD. Also, it is important to distinguish effects on surrogate endpoints, such as decreases in albuminuria and estimated glomerular filtration rate (eGFR), and hard clinical endpoints, such as progression to end-stage renal disease (ESRD) and death from renal causes. Data regarding insulin therapy are surprisingly scarce, and it is nearly impossible to separate the effects of better glucose control from those of insulin per se, whereas favourable preclinical data with metformin, thiazolidinediones and dipeptidyl peptidase (DPP)-4 inhibitors are plentiful, and positive effects have been observed in clinical studies, at least for surrogate endpoints. The most favourable renal results have been reported with glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter type-2 inhibitors (SGLT2is). Significant reductions in both albuminuria and eGFR decline have been reported with these classes of glucose-lowering medications compared with placebo and other glucose-lowering agents. Moreover, in large prospective cardiovascular outcome trials using composite renal outcomes as secondary endpoints, both GLP-1RAs and SGLT2is added to standard care reduced renal outcomes combining persistent macro-albuminuria, doubling of serum creatinine, progression to ESRD and kidney-related death; however, to date, only SGLT2is have been clearly shown to reduce such hard clinical outcomes. Yet, as the renoprotective effects of SGLT2is and GLP-1RAs appear to be independent of glucose-lowering activity, the underlying mechanisms are still a matter of debate. For this reason, further studies with renal outcomes as primary endpoints are now awaited in T2DM patients at high risk of DKD, including trials evaluating the potential add-on benefits of combined GLP-1RA-SGLT2i therapies.

Maintenance of Kidney Metabolic Homeostasis by PPAR Gamma

Peroxisome proliferator-activated receptors (PPARs) are a family of nuclear hormone receptors that control the transcription of specific genes by binding to regulatory DNA sequences. Among the three subtypes of PPARs, PPARγ modulates a broad range of physiopathological processes, including lipid metabolism, insulin sensitization, cellular differentiation, and cancer. Although predominantly expressed in adipose tissue, PPARγ expression is also found in different regions of the kidney and, upon activation, can redirect metabolism. Recent studies have highlighted important roles for PPARγ in kidney metabolism, such as lipid and glucose metabolism and renal mineral control. PPARγ is also implicated in the renin-angiotensin-aldosterone system and, consequently, in the control of systemic blood pressure. Accordingly, synthetic agonists of PPARγ have reno-protective effects both in diabetic and nondiabetic patients. This review focuses on the role of PPARγ in renal metabolism as a likely key factor in the maintenance of systemic homeostasis.

A systematic review comparing the evidence for kidney function outcomes between oral antidiabetic drugs for type 2 diabetes

Background: The development of kidney disease is a serious complication among people with type 2 diabetes mellitus, associated with substantially increased morbidity and mortality.  We aimed to summarise the current evidence for the relationship between treatments for type 2 diabetes and long-term kidney outcomes, by conducting a systematic search and review of relevant studies. Methods: We searched Medline, Embase and Web of Science, between 1st January 1980 and 15th May 2018 for published clinical trials and observational studies comparing two or more classes of oral therapy for type 2 diabetes. We included people receiving oral antidiabetic drugs. Studies were eligible that; (i) compared two or more classes of oral therapy for type 2 diabetes; (ii) reported kidney outcomes as primary or secondary outcomes; (iii) included more than 100 participants; and (iv) followed up participants for 48 weeks or more. Kidney-related outcome measures included were Incidence of chronic kidney disease, reduced eGFR, increased creatinine, 'micro' and 'macro' albuminuria. Results: We identified 15 eligible studies, seven of which were randomised controlled trials and eight were observational studies. Reporting of specific renal outcomes varied widely. Due to variability of comparisons and outcomes meta-analysis was not possible. The majority of comparisons between treatment with metformin or sulfonylurea indicated that metformin was associated with better renal outcomes. Little evidence was available for recently introduced treatments or commonly prescribed combination therapies. Conclusions: Comparative evidence for the effect of treatments for type 2 diabetes on renal outcomes, either as monotherapy or in combination is sparse.

Interplay between the renin-angiotensin system, the canonical WNT/β-catenin pathway and PPARγ in hypertension

PURPOSE OF REVIEW

Heterogeneous causes can determinate hypertension.

RECENT FINDINGS

The renin-angiotensin system (RAS) has a major role in the pathophysiology of blood pressure. Angiotensin II and aldosterone are overexpressed during hypertension and lead to hypertension development and its cardiovascular complications. In several tissues, the overactivation of the canonical WNT/β-catenin pathway leads to inactivation of peroxisome proliferator-activated receptor gamma (PPARγ), while PPARγ stimulation induces a decrease of the canonical WNT/β-catenin pathway. In hypertension, the WNT/β-catenin pathway is upregulated, whereas PPARγ is decreased. The WNT/β-catenin pathway and RAS regulate positively each other during hypertension, whereas PPARγ agonists can decrease the expression of both the WNT/β-catenin pathway and RAS. We focus this review on the hypothesis of an opposite interplay between PPARγ and both the canonical WNT/β-catenin pathway and RAS in regulating the molecular mechanism underlying hypertension. The interactions between PPARγ and the canonical WNT/β-catenin pathway through the regulation of the renin-angiotensin system in hypertension may be an interesting way to better understand the actions and the effects of PPARγ agonists as antihypertensive drugs.

The Preventive Role of Pioglitazone in Glycerol-Induced Acute Kidney Injury in Rats during Two Different Treatment Periods

BACKGROUND

Acute kidney injury is the most life-threatening complication of rhabdomyolysis. Glycerol is commonly used to induce this injury. The aim was to investigate the renoprotective effects of pioglitazone and the possible advantage of administering the drug for a longer period.

METHODS

Twenty-four male Albino Wistar rats were randomly divided into 4 groups (n=6/group): (A) control, (B) glycerol (50%, 10 mL/kg intramuscularly), (C) glycerol+pioglitazone (10 mg/kg orally for 3 days), and (D) glycerol+pioglitazone (for 6 days). Serum urea and creatinine levels were measured to assess the renal function. Reduced glutathione (GSH) levels and histological alterations were also measured. Statistical analysis was performed using Prism (version 6). The numerical data were evaluated by ANOVA, followed by the Tukey tests. The categorical data were evaluated by the Mann-Whitney test and the Fisher exact tests. P<0.05 was considered significant.

RESULTS

In the glycerol-injected rats, the serum urea and creatinine levels were increased (P<0.001), while the GSH levels were decreased (P<0.001) compared to Group A. The nephrotoxicity showed significant tubular (P=0.01) and glomerular (P=0.02) injuries. In the pioglitazone-treated rats, the changes in the serum biomarkers and in the GSH levels were reversed in Group C (P=0.01) and in Group D (P=0.01). The microscopic examinations of the kidneys also showed some improvement. No obvious statistically significant difference was found between these 2 preventive groups in most studied features.

CONCLUSION

These results indicate that pioglitazone might have nephroprotective effects in this injury model. Pioglitazone succeeded in producing this effect within 3 days. Doubling the drug administration period did not produce any significant superior benefit.

Characteristics of frequent emergency department users with type 2 diabetes mellitus in Korea

AIMS/INTRODUCTION

Frequent emergency department (ED) visitors are medically vulnerable individuals. We identified the characteristics of "frequent ED users" among Korean patients with type 2 diabetes mellitus.

MATERIALS AND METHODS

We used the Health Insurance Review and Assessment Service National Patient Sample, which is a nationally representative sample. Patients (n = 109,412) with type 2 diabetes mellitus as a primary or secondary diagnosis at one of their visits were included. Individuals were classified into three groups according to the number of ED visits: frequent (≥4 visits), occasional (<4 visits) and non-users of the ED. The characteristics of the patients that distinguished frequent users from the other groups were investigated.

RESULTS

Frequent ED users were mainly men (P < 0.001), with longer treatment duration (P < 0.001), more frequent comorbidities (cardiovascular and chronic kidney disease) and primary diagnosis made by surgery (P = 0.0028). They had higher mortality (P = 0.0085), longer hospitalization duration (P < 0.001), higher costs per visit (P < 0.001) and more often required medical protection (P < 0.001). These patients were treated more frequently with sulfonylurea, insulin, meglitinide and alpha-glucosidase inhibitors (P < 0.05).

CONCLUSIONS

The present findings suggest that frequent users of the ED with type 2 diabetes mellitus have serious health conditions, a poor socioeconomic situation and tend to take some medicines (sulfonylurea, etc.), which often are associated with hypoglycemia. Attention should be given to therapy, and to patients with renal and cardiovascular diseases to decrease the dependency of these patients on the ED.

Pharmacotherapy of type 2 diabetes: An update

Type 2 diabetes (T2DM) is a leading cause of morbidity and mortality worldwide and a major economic burden. The prevalence of T2DM is rising, suggesting more effective prevention and treatment strategies are necessary. The aim of this narrative review is to summarize the pharmacologic treatment options available for patients with T2DM. Each therapeutic class is presented in detail, outlining medication effects, side effects, glycemic control, effect on weight, indications and contraindications, and use in selected populations (heart failure, renal insufficiency, obesity and the elderly). We also present representative cost for each antidiabetic category. Then, we provide an individualized guide for initiation and intensification of treatment and discuss the considerations and rationale for an individualized glycemic goal.

Pioglitazone ameliorates glomerular NLRP3 inflammasome activation in apolipoprotein E knockout mice with diabetes mellitus

Objective

The NLRP3 inflammasome plays an important role in the pathogenesis of inflammation in diabetic nephropathy (DN). Pioglitazone (PIO) has been found to exert an anti-inflammatory effect in patients with diabetes mellitus, but it is still unclear whether PIO exhibits a similar effect in DN. We aimed to explore the effect and underlying mechanism of PIO on DN, as well as investigate if NLRP3 is a pharmacologic target of PIO.

Methods

We divided 48 apolipoprotein E (apoE) (-/-) mice into 4 groups: apoE (-/-), apoE (-/-) with PIO, diabetic apoE (-/-), and diabetic apoE (-/-) with PIO. Wild type male C57BL/6 mice were used as controls (n = 8 per group). After 8 weeks of PIO treatment, we examined the baseline characteristics and metabolic parameters of each group, and we used enzyme-linked immunosorbent assay (ELISA), western blot, and immunohistochemical staining to evaluate the expression levels of advanced glycation end products (AGEs), receptor for advanced glycation end products (RAGE), NLRP3, nuclear factor—kappa B (NF-κB), caspase-1, interleukin (IL)-18, and IL-1β in each group.

Results

Compared to the diabetic apoE (-/-) group, PIO treatment decreased blood glucose, cholesterol, serum blood urea nitrogen (BUN), and creatinine levels. It also depressed the glomerular mesangial expansion. PIO down-regulated expression of AGEs, RAGE, and NF-κB, all of which further depressed NLRP3, caspase-1, IL-18, and IL-1β levels.

Conclusion

Pioglitazone can ameliorate diabetic renal damage, and this effect is related to the inhibition of renal AGE/RAGE axis activation and the down-regulation of NF-κB expression. These effects lead to a decline in NLRP3 levels and downstream secretion of inflammatory cytokines.

The impact of antihypertensives on kidney disease

Arterial hypertension and chronic kidney disease (CKD) are intimately related. The control of blood pressure (BP) levels is strongly recommended in patients with CKD in order to protect the kidney against the accompanying elevation in global cardiovascular (CV) risk. Actually, the goal BP in patients with CKD involves attaining values <140/90 mmHg except if albuminuria is present. In this case, it is often recommended to attain values <130/80 mmHg, although some guidelines still recommend <140/90 mmHg. Strict BP control to values of systolic BP around 120 mmHg was recently shown to be safe in CKD according to data from the SPRINT trial, albeit more data confirming this benefit are required. Usually, combination therapy initiated with an angiotensin receptor blocker (ARB) or angiotensin-converting enzyme inhibitor (ACEi) and commonly followed by the addition of a calcium channel blocker and a diuretic is needed. Further studies are required as well as new drugs in particular after the positive data obtained from new oral anti-diabetic drugs.

Reducing VEGF-B Signaling Ameliorates Renal Lipotoxicity and Protects against Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the most common cause of severe renal disease, and few treatment options are available today that prevent the progressive loss of renal function. DKD is characterized by altered glomerular filtration and proteinuria. A common observation in DKD is the presence of renal steatosis, but the mechanism(s) underlying this observation and to what extent they contribute to disease progression are unknown. Vascular endothelial growth factor B (VEGF-B) controls muscle lipid accumulation through regulation of endothelial fatty acid transport. Here, we demonstrate in experimental mouse models of DKD that renal VEGF-B expression correlates with the severity of disease. Inhibiting VEGF-B signaling in DKD mouse models reduces renal lipotoxicity, re-sensitizes podocytes to insulin signaling, inhibits the development of DKD-associated pathologies, and prevents renal dysfunction. Further, we show that elevated VEGF-B levels are found in patients with DKD, suggesting that VEGF-B antagonism represents a novel approach to treat DKD.

Renal Outcomes of Pioglitazone Compared with Acarbose in Diabetic Patients: A Randomized Controlled Study

Objective

To assess the effect of pioglitazone on renal outcome, including urinary albumin excretion and estimated glomerular filtration rate (eGFR), in diabetic patients.

Design

A prospective, randomized, open-labeled, controlled study.

Setting

Taipei Veterans General Hospital.

Patients

Sixty type 2 diabetic patients treated with sulfonylureas and metformin, whose glycated hemoglobin (HbA1c) levels were between 7% and 10% and eGFR was between 45 and 125 mL/min/1.73 m².

Intervention

The patients were randomized to receive acarbose or pioglitazone and followed up for 6 months. Thirty patients were randomly assigned to receive acarbose, and 30 patients were assigned to receive pioglitazone.

Measurements

The primary study endpoint was the changes in the urinary albumin-to-creatinine ratio (UACR). The secondary endpoint was the changes in eGFR and other parameters.

Results

After 6 months of treatment, the mean changes in UACR were −18 ± 104 and 12 ± 85 (p = 0.25, between groups) for the acarbose and pioglitazone groups, respectively. The mean changes in eGFR were 0 ± 14 and −7 ± 16 mL/min/1.73 m² (p = 0.09, between groups) for the acarbose and pioglitazone groups, respectively. The reductions in HbA1c were similar in both groups. Fasting blood glucose was lower in the pioglitazone group than in the acarbose group. Significant body weight gain was observed in the pioglitazone group as compared with the acarbose group (1.3 ± 2.8 vs. −0.6 ± 1.5 kg, p = 0.002).

Conclusion

In type 2 diabetic patients who were treated with sulfonylureas and metformin and possessed HbA1c levels between 7% and 10%, additional acarbose or pioglitazone for 6 months provided similar glycemic control and eGFR and UACR changes. In the pioglitazone group, the patients exhibited significant body weight gain.

Trial Registration

ClinicalTrials.gov NCT01175486

The Management of Diabetes Mellitus in Patients with Chronic Kidney Disease: A Population-Based Study in Southern Italy

BACKGROUND AND OBJECTIVES

Diabetes mellitus in patients with chronic kidney disease (CKD) is known as diabetic kidney disease (DKD). Pharmacological management of DKD is challenging due to reduced renal excretion of some antidiabetic drugs. The aim of this population-based study was to explore antidiabetic drug use in DKD patients from Southern Italy.

METHODS

The Arianna database from Caserta Local Health Unit was used. Diabetic patients with incident CKD [first diagnosis date: index date (ID)] were identified by searching for specific ICD9-CM codes among hospital discharge diagnoses/procedures and/or indication of use associated with drug prescriptions. To evaluate any change in the use of antidiabetic drugs after the CKD diagnosis, the prevalence of antidiabetic drug use among DKD patients was calculated within 1 year prior to/after ID and after dialysis entry. A Kaplan-Meier analysis was used to assess the time to discontinuation of antidiabetic drugs after CKD diagnosis. The frequency of antidiabetic drugs contraindicated in renal disease in DKD patients was measured.

RESULTS

Overall, 725 diabetic patients (mean age 72.8 ± 11.4 years) had incident CKD from 2006 to 2011. The use of combination antidiabetic drugs, biguanides and sulphonamides decreased by approximately 10, 7 and 5%, respectively, after the ID. The use of insulins increased by 10% after the ID and by 20% after entry into dialysis. The use of antidiabetic drugs not contraindicated in CKD decreased marginally after the diagnosis of CKD.

CONCLUSION

In a general practice of Southern Italy the management of diabetes mellitus changed only marginally in newly diagnosed CKD patients, suggesting a therapeutic inertia on the part of prescribers.

Autophagy protects human podocytes from high glucose-induced injury by preventing insulin resistance

OBJECTIVE

Insulin resistance is correlated with the progress of albuminuria in diabetic patients, and podocytes are crucial for maintaining the normal function of the glomerular filtration barrier. In the present study, we aimed to investigate the high glucose-induced insulin resistance and cell injury in human podocytes and the putative role of autophagy in this process.

METHODS

Human podocytes were cultured in high glucose-supplemented medium and low glucose and high osmotic conditions were used for the controls. Autophagy in the podocytes was regulated using rapamycin or 3-methyladenine stimulation. Next, autophagy markers including LC3B, Beclin-1, and p62 were investigated using western blot and qPCR, and the insulin responsiveness was analyzed based on glucose uptake and by using the phosphorylation of the insulin receptor with Nephrin as a podocyte injury marker.

RESULTS

The basal autophagy level decreased under the high glucose conditions, which was accompanied by a decrease in the glucose uptake and phosphorylation of the insulin receptor in the human podocytes. More interestingly, the glucose uptake and the phosphorylation of the insulin receptor were decreased by 3-MA stimulation and increased by rapamycin, illustrating that the responsiveness of insulin was regulated by autophagy. The activation of autophagy by rapamycin also ameliorated cell injury in the human podocytes.

CONCLUSIONS

The presence or activation of autophagy was found to play a protective role in human podocytes against high glucose-induced insulin resistance and cell injury, which indicates a novel cellular mechanism and provides a potential therapeutic target for diabetic nephropathy (DN).

The dose-response effect of insulin sensitivity on albuminuria in children according to diabetes type

BACKGROUND

Insulin resistance is associated with microalbuminuria among youth with diabetes mellitus. We sought to determine the dose-response effect of insulin sensitivity (IS) on the magnitude of albuminuria and whether there is a threshold below which urine albumin excretion increases.

METHODS

These analyses included participants from the SEARCH for Diabetes in Youth Study with incident diabetes who completed a baseline study visit (n = 2988). We estimated IS using a validated equation incorporating waist circumference, HbA1C, and fasting serum triglycerides. Multivariate regression analyses were performed to assess the effect of IS on urine albumin creatinine ratio (UACR), stratified by diabetes type. The IS threshold was then determined using segmented regressions within each diabetes type and incorporated into the multivariate model.

RESULTS

There was an association between IS and UACR in type 2 diabetes only (beta = -0.39; p < 0.001). There was strong statistical evidence for a threshold effect of IS score on UACR in the group of youth with type 2 (beta = 0.40; p < 0.001) but not type 1 diabetes (p = 0.3).

CONCLUSIONS

In cross-sectional analyses, there is a negative association between IS and UACR in youth with type 2 but not type 1 diabetes, and this association likely includes a threshold effect of IS on UACR.

Renoprotective effect of DPP-4 inhibitors against free fatty acid-bound albumin-induced renal proximal tubular cell injury

Dipeptidyl peptidase (DPP)-4 inhibitors, a new class of antidiabetic agent, have recently been suggested to exert pleiotropic effects beyond glucose lowering. Renal prognosis in patients with diabetic nephropathy depends on the severity of tubulointerstitial injury induced by massive proteinuria. We thus examined the renoprotective effect of DPP-4 inhibitors on inflammation in cultured mouse proximal tubular cells stimulated with free fatty acid (FFA)-bound albumin. Linagliptin and higher concentrations of sitagliptin, vildagliptin, and alogliptin all inhibited FFA-bound albumin-induced increases in mRNA expression of MCP-1 in cultured mouse proximal tubular cells. Furthermore, linagliptin significantly inhibited tubulointerstitial injury induced by peritoneal injection of FFA-bound albumin, such as inflammation, fibrosis, and apoptosis, in mice without altering systemic characteristics including body weight, fasting blood glucose, and food intake. These results indicate that DPP-4 inhibitors pleiotropically exert a direct renoprotective effect, and may serve as an additional therapeutic strategy to protect proximal tubular cells against proteinuria in patients with diabetic nephropathy.

Additive Renoprotection by Pioglitazone and Fenofibrate against Inflammatory, Oxidative and Apoptotic Manifestations of Cisplatin Nephrotoxicity: Modulation by PPARs

Nephrotoxicity is a major side effect for the antineoplastic drug cisplatin. Here, we employed pharmacological, biochemical, and molecular studies to investigate the role of peroxisome proliferator-activated receptors (PPARs) in cisplatin nephrotoxicity. Rats were treated with a single i.p. dose of cisplatin (5 mg/kg) alone or combined with pioglitazone (PPARγ agonist), fenofibrate (PPARα agonist), pioglitazone plus fenofibrate, or thalidomide (Tumor necrosis factor-α inhibitor; TNF-α). Cisplatin nephrotoxicity was evidenced by rises in renal indices of functional (blood urea nitrogen, BUN, and creatinine), inflammatory (TNF-α, interleukin 6, IL-6), oxidative (increased malondialdehyde, MDA, and decreased superoxide dismutase, SOD and nitric oxide metabolites, NOx), apoptotic (caspase 3), and histological (glomerular atrophy, acute tubular necrosis and vacuolation) profiles. Cisplatin effects were partly abolished upon concurrent exposure to pioglitazone, fenofibrate, or thalidomide; more renoprotection was observed in rats treated with pioglitazaone plus fenofibrate. Immunostaining showed that renal expressions of PPARα and PPARγ were reduced by cisplatin and restored to vehicle-treated values after simultaneous treatment with pioglitazone or fenofibrate. Fenofibrate or pioglitazone renoprotection remained unaltered after concurrent blockade of PPARα (GW6471) and PPARγ (GW9662), respectively. To complement the rat studies, we also report that in human embryonic kidney cells (HEK293 cells), increases caused by cisplatin in inflammatory, apoptotic, and oxidative biomarkers were (i) partly improved after exposure to pioglitazone, fenofibrate, or thalidomide, and (ii) completely disappeared in cells treated with a combination of all three drugs. These data establish that the combined use of pioglitazone and fenofibrate additively improved manifestations of cisplatin nephrotoxicity through perhaps GW6471/GW9662-insensitive mechanisms.

Nephroprotection by Hypoglycemic Agents: Do We Have Supporting Data?

Current therapy directed at delaying the progression of diabetic nephropathy includes intensive glycemic and optimal blood pressure control, renin angiotensin-aldosterone system blockade and multifactorial intervention. However, the renal protection provided by these therapeutic modalities is incomplete. There is a scarcity of studies analysing the nephroprotective effect of antihyperglycaemic drugs beyond their glucose lowering effect and improved glycaemic control on the prevention and progression of diabetic nephropathy. This article analyzes the exisiting data about older and newer drugs as well as the mechanisms associated with hypoglycemic drugs, apart from their well known blood glucose lowering effect, in the prevention and progression of diabetic nephropathy. Most of them have been tested in humans, but with varying degrees of success. Although experimental data about most of antihyperglycemic drugs has shown a beneficial effect in kidney parameters, there is a lack of clinical trials that clearly prove these beneficial effects. The key question, however, is whether antihyperglycemic drugs are able to improve renal end-points beyond their antihyperglycemic effect. Existing experimental data are post hoc studies from clinical trials, and supportive of the potential renal-protective role of some of them, especially in the cases of dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter 2 inhibitors. Dedicated and adequately powered renal trials with renal outcomes are neccessary to assess the nephrotection of antihyperglycaemic drugs beyond the control of hyperglycaemia.

Insulin signaling: implications for podocyte biology in diabetic kidney disease

PURPOSE OF REVIEW

Several key elements of the insulin signaling cascade contribute to podocyte function and survival. While it was initially thought that the consequences of altered insulin signaling to podocyte function was strictly related to altered glucose uptake, it has become clear that upstream signaling events involved in cell survival, lipid metabolism or nutrient sensing and modulated by insulin are strong independent contributors to podocyte function.

RECENT FINDINGS

Akt2, the major isoform of Akt activated following cellular insulin stimulation, protects against the progression of renal disease in nephron-deficient mice, and podocyte-specific deletion of Akt2 results in a more rapid progression of experimental glomerular disease. In diabetes, podocyte mammalian target of rapamycin activation clearly contributes to podocyte injury and regulated autophagy. Furthermore, podocyte-specific glucose transporter type 4 (GLUT4) deficiency protects podocytes by preventing mammalian target of rapamycin signaling independently of glucose uptake. Finally, intracellular lipids have been recently recognized as major modulators of podocyte insulin signaling and as a new therapeutic target.

SUMMARY

The identification of new contributors to podocyte insulin signaling is of extreme translational value as it may lead to new drug development strategies for diabetic kidney disease, as well as for other proteinuric kidney diseases.