The roles of sodium-glucose cotransporter 2 inhibitors in preventing kidney injury in diabetes. Biomed Pharmacother. 2017;94:176-187. [PMID: 28759755 DOI: 10.1016/j.biopha.2017.07.095]

Mechanistic Modeling of Empagliflozin: Predicting Pharmacokinetics, Urinary Glucose Excretion, and Investigating Compensatory Role of SGLT1 in Renal Glucose Reabsorption

The aim of this study was to use a combination of physiologically based pharmacokinetic (PBPK) modeling and urinary glucose excretion (UGE) modeling to predict the time profiles of pharmacokinetics (PK) and UGE for the sodium-glucose cotransporter 2 (SGLT2) inhibitor empagliflozin (EMP). Additionally, the study aims to explore the compensatory effect of SGLT1 in renal glucose reabsorption (RGR) when SGLT2 is inhibited. The PBPK-UGE model was developed using physicochemical and biochemical properties, renal physiological parameters, binding kinetics, glucose, and Na+ reabsorption kinetics by SGLT1/2. For area under the plasma concentration-time curve, maximum plasma concentration, and cumulative EMP excretion in urine, the predicted values fell within a range of 0.5-2.0 when compared to observed data. Additionally, the simulated UGE data also matched well with the clinical data, further validating the accuracy of the model. According to the simulations, SGLT1 and SGLT2 contributed approximately 13% and 87%, respectively, to RGR in the absence of EMP. However, in the presence of EMP at doses of 2.5 and 10 mg, the contribution of SGLT1 to RGR significantly increased to approximately 76%-82% and 89%-93%, respectively, in patients with type 2 diabetes mellitus. Furthermore, the model supported the understanding that the compensatory effect of SGLT1 is the underlying mechanism behind the moderate inhibition observed in total RGR. The PBPK-UGE model has the capability to accurately predict the PK and UGE time profiles in humans. Furthermore, it provides a comprehensive analysis of the specific contributions of SGLT1 and SGLT2 to RGR in the presence or absence of EMP.

Transcriptome analysis provides insights into high fat diet-induced kidney injury and moderate intensity continuous training-mediated protective effects

Although physics exercise has been utilized to prevent and treat a variety of metabolic diseases, its role in obesity-related kidney diseases remains poorly understood. In this study, we assessed the protective potential of moderate intensity continuous training (MICT) against high fat diet (HFD)-induced kidney injury and found that MICT could significantly reduce obesity indexes (body weight, serum glucose, total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol) and kidney injury indexes (serum creatinine and the expression of Kim-1 mRNA) in HFD-fed mice. PAS staining and Masson staining displayed that MICT maintained the morphological structure of kidney subunits and reduced kidney fibrosis in HFD-fed mice. By kidney RNA-seq, we identified several genes and pathways (Cd9, Foxq1, Mier3, TGF-β signaling pathway etc.) that might underlie HFD-induced kidney injury and MICT-mediated protective effects. In conclusion, this study revealed the protective role of MICT in HFD-induced kidney injury and suggested potential targets for the prevention and treatment of obesity-related kidney diseases.

Canagliflozin ameliorates high glucose-induced apoptosis in NRK-52E cells via inhibiting oxidative stress and activating AMPK/mTOR-mediated autophagy

BACKGROUND

Sodium-glucose cotransporter-2 (SGLT-2) inhibitors, as a new type of hypoglycemic drug, can prevent proximal renal tubule injury related to glucose toxicity and play a renoprotective role. Canagliflozin, a recognized SGLT-2 inhibitor, has been proved to have potential protection in diabetic nephropathy (DN), but its mechanism has not been fully elucidated. In this study, the protective effect of canagliflozin against high glucose (HG)-induced renal tubular epithelial cell (NRK-52E) injury in vitro was assessed.

METHODS

The viability and apoptosis of NRK-52E cells were detected using cell counting kit-8 (CCK-8) assay and flow cytometry analysis, respectively. The expression levels of cleaved caspase-3, oxidative stress-related proteins (NOX4 and Nrf2), autophagy marker light chain 3 (LC3) I/II, and adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathway-related proteins were evaluated by Western blot. Reactive oxygen species (ROS) level was evaluated by dihydroethidium (DHE) reactive oxygen species assay, the activities of SOD, CAT, GSH-Px and MDA were analyzed using kits. The changes of morphology and red fluorescent protein (RFP)-LC3 fluorescence were observed under microscopy.

RESULTS

Canagliflozin significantly ameliorated HG-induced NRK-52E cell apoptosis and caspase-3 cleavage. Furthermore, canagliflozin markedly ameliorated HG-induced NRK-52E cell oxidative stress. Moreover, canagliflozin significantly increased LC3-II levels and induced RFP-LC3-containing punctate structures in NRK-52E cells. Finally, canagliflozin increased the phosphorylation of AMPK and suppressed the phosphorylation of mTOR. The AMPK inhibitor compound C abolished canagliflozin-induced autophagy activation, as well as the anti-apoptotic effect of canagliflozin.

CONCLUSION

Canagliflozin effectively ameliorate HG-induced apoptosis of NRK-52E cells in vitro that involved its antioxidant effect and induction of autophagy through the AMPK/mTOR pathway.

Evaluation of Pharmacokinetic Interactions Between the New SGLT2 Inhibitor SHR3824 and Valsartan in Healthy Chinese Volunteers

PURPOSE

Hypertension is often observed in patients with diabetes, and the progression of diabetic nephropathy is closely related to blood pressure elevation. Thus, the effects of hypoglycemic drugs on kidney function and pharmacokinetic interactions in combination with antihypertensive and hypoglycemic drugs are of great clinical value. The purpose of this study was to evaluate the pharmacokinetic interactions between henagliflozin (SHR3824), a new sodium-dependent glucose transporter 2 (SGLT2) inhibitor class drug, and valsartan, an angiotensin II receptor blocker.

METHODS

A single-center, single-arm, open-label, self-controlled study was conducted in healthy Chinese volunteers. The pharmacokinetic parameters were calculated with Phoenix WinNonlin version 7.0, and the statistical analysis was performed with SAS version 9.4. Data on pharmacokinetic parameters (single and/or steady-state) were collected and tabulated for different analytes (valsartan and SHR3824) according to the sampling time specified in the protocol. Continuous attention was paid to the safety of all subjects. The aim of the study was to evaluate the effect of a single dose of valsartan on the pharmacokinetic behavior of SHR3824 after multiple doses of SHR3824 (C_max,ss and AUC_τ,ss) and the effect of multiple doses of SHR3824 on the pharmacokinetic behavior of valsartan (C_max, AUC_0-24h, and AUC_0-∞). A mixed effect model was used to estimate the point estimation and 90% CI of the geometric mean ratio of the corresponding pharmacokinetic indices at the combined-medication stage (SHR3824 + valsartan) and the single-medication stage (SHR3824 or valsartan).

FINDINGS

Twelve volunteers were screened into this experiment and underwent blood sampling. The pharmacokinetic properties of SHR3824 were evaluated after its administration alone or in combination with valsartan. Point estimates and 90% CIs of the geometric mean ratio of SHR3824 C_max,ss and AUC_τ,ss were within the conventional bioequivalence range of 80% to 125%. The pharmacokinetic properties of valsartan were evaluated after its administration alone or in combination with SHR3824. The geometric mean ratios and 90% CIs of the valsartan C_max, AUC_0-24h, and AUC_0-∞ were also within the range of 80% to 125%. Thirty-four mild adverse events were reported, with no serious adverse events or suspected unexpected serious adverse reactions.

IMPLICATIONS

This study provides basis for the clinical co-administration of SHR3824 with angiotensin II receptor blockers represented by valsartan. Based on these findings, co-administration of SHR3824 and valsartan seemed to have no effect on the pharmacokinetic properties of either drug. Chinadrugtrials.org.cn Identifier: CTR20180002.

Kidney Damage Caused by Obesity and Its Feasible Treatment Drugs

The rapid growth of obesity worldwide has made it a major health problem, while the dramatic increase in the prevalence of obesity has had a significant impact on the magnitude of chronic kidney disease (CKD), especially in developing countries. A vast amount of researchers have reported a strong relationship between obesity and chronic kidney disease, and obesity can serve as an independent risk factor for kidney disease. The histological changes of kidneys in obesity-induced renal injury include glomerular or tubular hypertrophy, focal segmental glomerulosclerosis or bulbous sclerosis. Furthermore, inflammation, renal hemodynamic changes, insulin resistance and lipid metabolism disorders are all involved in the development and progression of obesity-induced nephropathy. However, there is no targeted treatment for obesity-related kidney disease. In this review, RAS inhibitors, SGLT2 inhibitors and melatonin would be presented to treat obesity-induced kidney injury. Furthermore, we concluded that melatonin can protect the kidney damage caused by obesity by inhibiting inflammation and oxidative stress, revealing its therapeutic potential.

The Molecular Effects of SGLT2i Empagliflozin on the Autophagy Pathway in Diabetes Mellitus Type 2 and Its Complications

BACKGROUND

Type 2 diabetes mellitus (T2DM), especially hyperglycemia, is associated with increased glucose cell toxicity and oxidative stress that can lead to irreversible damage in the kidney such as diabetic nephropathy (DN). Autophagy plays a key role in the degradation of damaged intracellular proteins in order to maintain intracellular homeostasis and cell integrity. The disturbance of autophagy is involved in the pathogenesis of diabetic nephropathy. We aim to investigate the molecular effect of sodium-glucose transporter 2 inhibitor (SGLT2i) on the expression of ATG5 and its downstream collaborator LC3-II in diabetic nice model. Material and Methods. We used eight weeks old male mice: twenty C57BL/6 wild type (C57BL/6), twenty BTBR ob/ob (DM), and twenty BTBR ob/ob that were treated with empagliflozin (DM+EMPA), FDA approved SGLT2i. Lysate from murine renal cortex was analyzed by Western blot and immunohistochemistry. ATG5, LC3B, and fibronectin expression were analyzed in murine kidney tissues. All mice were sacrificed 13 weeks after the beginning of the experiment.

RESULTS

Histological and Western blot analyses reveal decrease ATG5, LC3-II, and fibronectin levels at renal specimens taken from DM mice. EMPA treatment reduced T2DM mice body weight and blood glucose and increased urine glucose. Further, it upregulated all of the abovementioned proteins.

CONCLUSIONS

Hyperglycemia reduces LC3-II and ATG5 protein levels which contribute to deficiencies in the autophagy process, with development and progression of DN. SGLT2i significantly reduces progression of DN and onset of end-stage renal disease in T2DM patients, probably through its effect on autophagy.

Autophagy Dysregulation in Diabetic Kidney Disease: From Pathophysiology to Pharmacological Interventions

Diabetic kidney disease (DKD) is a frequent, potentially devastating complication of diabetes mellitus. Several factors are involved in its pathophysiology. At a cellular level, diabetic kidney disease is associated with many structural and functional alterations. Autophagy is a cellular mechanism that transports intracytoplasmic components to lysosomes to preserve cellular function and homeostasis. Autophagy integrity is essential for cell homeostasis, its alteration can drive to cell damage or death. Diabetic kidney disease is associated with profound autophagy dysregulation. Autophagy rate and flux alterations were described in several models of diabetic kidney disease. Some of them are closely linked with disease progression and severity. Some antidiabetic agents have shown significant effects on autophagy. A few of them have also demonstrated to modify disease progression and improved outcomes in affected patients. Other drugs also target autophagy and are being explored for clinical use in patients with diabetic kidney disease. The modulation of autophagy could be relevant for the pharmacological treatment and prevention of this disease in the future. Therefore, this is an evolving area that requires further experimental and clinical research. Here we discuss the relationship between autophagy and Diabetic kidney disease and the potential value of autophagy modulation as a target for pharmacological intervention.

Current Challenges and Future Perspectives of Renal Tubular Dysfunction in Diabetic Kidney Disease

Over decades, substantial progress has been achieved in understanding the pathogenesis of proteinuria in diabetic kidney disease (DKD), biomarkers for DKD screening, diagnosis, and prognosis, as well as novel hypoglycemia agents in clinical trials, thereby rendering more attention focused on the role of renal tubules in DKD. Previous studies have demonstrated that morphological and functional changes in renal tubules are highly involved in the occurrence and development of DKD. Novel tubular biomarkers have shown some clinical importance. However, there are many challenges to transition into personalized diagnosis and guidance for individual therapy in clinical practice. Large-scale clinical trials suggested the clinical relevance of increased proximal reabsorption and hyperfiltration by sodium-glucose cotransporter-2 (SGLT2) to improve renal outcomes in patients with diabetes, further promoting the emergence of renal tubulocentric research. Therefore, this review summarized the recent progress in the pathophysiology associated with involved mechanisms of renal tubules, potential tubular biomarkers with clinical application, and renal tubular factors in DKD management. The mechanism of kidney protection and impressive results from clinical trials of SGLT2 inhibitors were summarized and discussed, offering a comprehensive update on therapeutic strategies targeting renal tubules.

Taxifolin improves disorders of glucose metabolism and water-salt metabolism in kidney via PI3K/AKT signaling pathway in metabolic syndrome rats

AIMS

Our study was designed to explore the function and mechanism of taxifolin on glucose metabolism and water-salt metabolism in kidney with metabolic syndrome (MS) rats.

MAIN METHODS

Spontaneous hypertensive rats were induced by fructose to establish MS model. Systolic blood pressure (SBP) and homeostasis model assessment of insulin resistance (HOMA-IR) were measured after 7 weeks of continuous administration with taxifolin. Kidney injury indices and histopathological evaluation were done. The apoptosis rate of primary kidney cells was detected by flow cytometry. Insulin signaling pathway related proteins and renal glucose transport-related proteins were detected by western blotting. We assessed the effects of taxifolin on sodium water retention and renin-angiotensin-aldosterone system (RAAS) in MS rats. We examined not only changes in urine volume, osmotic pressure, urinary sodium and urinary chloride excretion, but also the effects on NA⁺/K⁺-ATPase and RAAS indicators. We also detected changes in inflammatory factors by immunohistochemical staining and immunofluorescence. In vitro experiment, high glucose and salt stimulated NRK-52E cells. By adding the PI3K inhibitor (wortmannin) to inhibit the PI3K, the effects of inhibiting the PI3K/AKT signaling pathway on glucose metabolism, water-sodium retention and inflammatory response were discussed.

KEY FINDINGS

Taxifolin effectively reversed SBP, HOMA-IR, the kidney indices and abnormal histopathological changes induced by MS. Besides, taxifolin called back the protein associated with the downstream glucose metabolism pathway of PI3K/AKT. It also inhibited overactivation of RAAS and inflammatory response. In vitro experiments have demonstrated that the PI3K/AKT signaling pathway plays an important role in this process.

SIGNIFICANCE

Taxifolin can improve homeostasis of glucose, inhibit overactivation of RAAS and reduce inflammatory response by PI3K/AKT signaling pathway.

Sodium-glucose cotransporter 2 inhibitors (SGLT2i): renal implications

Type 2 diabetes mellitus (DM2) is a chronic condition that affects more than 400 million individuals worldwide. In DM2 patients, an appropriate glycemic control slows the onset and delays the progression of all its micro and macrovascular complications. Even though there are several glucose-lowering drugs, only approximately half of patients achieve glycemic control, while undesirable adverse effects (e.g., low serum glucose) normally affect treatment. Therefore, there is a need for new types of treatments. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have just been developed for treating DM2. Renal hyperfiltration as a marker of increased intraglomerular pressure in diabetic patients, and the role of renin-angiotensin-aldosterone system (RAAS) in this phenomenon have been studied. Nevertheless, RAAS blockade does not completely reduce hyperfiltration or diabetic renal damage. In this sense, the contribution of renal tubular factors to the hyperfiltration state, including sodium-glucose cotransporter (SGLT), has been currently studied. SGLT2i reduce proximal tubular sodium reabsorption, therefore increasing distal sodium delivery to the macula densa, causing tubule-glomerular feedback activation, afferent vasoconstriction, and reduced hyperfiltration in animal models. In humans, SGLT2i was recently shown to reduce hyperfiltration in normotensive, normoalbuminuric patients suffering from type 1 diabetes mellitus. In DM2 clinical trials, SGLT2 is associated with significant hyperfiltration and albuminuria reduction. The aim of this article is to compile the information regarding SGLT2i drugs, emphasizing its mechanism of renal repercussion.

Ameliorative Effects of Bredemolic Acid on Markers Associated with Renal Dysfunction in a Diet-Induced Prediabetic Rat Model

Recently, studies have shown that renal dysfunction is associated not only with overt diabetes but also with the preceding stage known as prediabetes. Diet and pharmacological interventions are the therapeutic approaches to managing prediabetes, but the compliance in combining the two interventions is low. Hence, the efficacy of pharmacological intervention is reduced without diet modification. In our previous study, we established that bredemolic acid (BA) ameliorated glucose homeostasis via increased GLUT 4 expression in the skeletal muscle of prediabetic rats in the absence of diet intervention. However, the effects of bredemolic acid on renal function in prediabetic condition are unknown. Therefore, this study was aimed at investigating the ameliorative effects of bredemolic acid on renal dysfunction in a diet-induced prediabetic rat model. Thirty-six Sprague-Dawley male rats (150-180 g) were divided into two groups: the nonprediabetic (n = 6) and prediabetic (n = 30) groups which were fed normal diet (ND) and high-fat high-carbohydrate (HFHC) diet, respectively, for 20 weeks. After the 20^th week, the prediabetic groups were subdivided into prediabetic control (PD) and 4 other prediabetic groups which were treated with either BA (80 mg/kg) or metformin (MET, 500 mg/kg) for further 12 weeks (21^st to 32^nd). Plasma, urine, and kidney samples were collected for biochemical analysis. The untreated prediabetic (PD) rats presented increased fluid intake and urine output; increased creatinine, urea, and uric acid plasma concentrations; albuminuria; proteinuria; sodium retention; potassium loss; increased aldosterone and kidney injury molecule (KIM-1) concentration; and increased urinary podocin mRNA expression. However, BA administration attenuated the renal markers and oxidative stress and decreased the urinary podocin mRNA expression. In conclusion, BA administration, regardless of diet modification, attenuates renal dysfunction in an experimentally induced prediabetic state.

Effect of levosimendan, an inodilator, on streptozotocin-induced diabetic nephropathy in rats

This study examined the effect of levosimendan on streptozotocin-induced early diabetic nephropathy. Rats were distributed into four groups and treated for six weeks. The first and third group received either vehicle or levosimendan (1 mg/kg/day) for the last three weeks, respectively. The second and fourth groups were rendered diabetic by a single intraperitoneal injection of streptozotocin (60 mg/kg) and were treated as the first and third groups, respectively. In the untreated diabetic group, there was a significant decrease in body weight, polyuria and hyperglycemia as well as, increased urinary albumin/creatinine ratio (UACR) and N-acetyl-β-D-glucosaminidase (NAG)/creatinine ratio (UNCR) with no change in creatinine clearance. In addition, diabetes was associated with increased oxidative stress as evidenced by reduced plasma total antioxidant capacity (TAC) and catalase activity and increased plasma malondialdhyde (MDA) and the inflammatory marker, tumor necrosis factor-alpha, (TNF-α). Kidneys from streptozotocin-treated rats showed focal clear renal tubular cells affecting proximal convoluted tubules and mild interstitial fibrosis at the cortico-medullary junction. Levosimendan significantly attenuated the streptozotocin-induced physiological and biochemical changes and there was less clear renal tubular cells. This study shows that levosimendan ameliorated some of the changes seen in streptozotocin-induced early diabetic nephropathy in rats. This could be partly due to its antioxidative and anti-inflammatory effects.

Canagliflozin, a sodium-glucose cotransporter 2 inhibitor, normalizes renal susceptibility to type 1 cardiorenal syndrome through reduction of renal oxidative stress in diabetic rats

AIMS/INTRODUCTION

Type 2 diabetes mellitus is a risk factor of acute kidney injury after myocardial infarction (MI), a form of cardiorenal syndrome. Recent clinical trials have shown that a sodium-glucose cotransporter 2 (SGLT2) inhibitor improved both cardiac and renal outcomes in patients with type 2 diabetes mellitus, but effects of an SGLT2 inhibitor on cardiorenal syndrome remain unclear.

MATERIALS AND METHODS

Type 2 diabetes mellitus (Otsuka Long-Evans Tokushima Fatty rats [OLETF]) and control (Long-Evans Tokushima Otsuka rats [LETO]) were treated with canagliflozin, an SGLT2 inhibitor, for 2 weeks. Renal tissues were analyzed at 12 h after MI with or without preoperative fasting.

RESULTS

Canagliflozin reduced blood glucose levels in OLETF, and blood β-hydroxybutyrate levels were increased by canagliflozin only with fasting. MI increased neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 protein levels in the kidney by 3.2- and 1.6-fold, respectively, in OLETF, but not in LETO. The renal messenger ribonucleic acid level of Toll-like receptor 4 was higher in OLETF than in LETO after MI, whereas messenger ribonucleic acid levels of cytokines/chemokines were not significantly different. Levels of lipid peroxides, nicotinamide adenine dinucleotide phosphate oxidase (NOX)2 and NOX4 proteins after MI were significantly higher in OLETF than in LETO. Canagliflozin with pre-MI fasting suppressed MI-induced renal expression of neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 in OLETF, together with reductions in lipid peroxides and NOX proteins in the kidney. Blood β-hydroxybutyrate levels before MI were inversely correlated with neutrophil gelatinase-associated lipocalin protein levels in OLETF. Pre-incubation with β-hydroxybutyrate attenuated angiotensin II-induced upregulation of NOX4 in NRK-52E cells.

CONCLUSIONS

The findings suggest that SGLT2 inhibitor treatment with a fasting period protects kidneys from MI-induced cardiorenal syndrome, possibly by β-hydroxybutyrate-mediated reduction of NOXs and oxidative stress, in type 2 diabetic rats.

Novel pharmacological therapy in type 2 diabetes mellitus with established cardiovascular disease: Current evidence

Cardiovascular diseases (CVDs) remain the leading cause of death in the world and in most developed countries. Patients with type 2 diabetes mellitus (T2DM) suffer from both microvascular and macrovascular diseases and therefore have higher rates of morbidity and mortality compared to those without T2DM. If current trends continue, the Center for Disease Control and Prevention estimates that 1 in 3 Americans will have T2DM by year 2050. As a consequence of the controversy surrounding rosiglitazone and the increasing prevalence of diabetes and CVDs, in 2008 the Food and Drug Administration (FDA) established new expectations for the evaluation of new antidiabetic agents, advising for pre and, in some cases, post-marketing data on major cardiovascular events. As a direct consequence, there has been a paradigm shift in new antidiabetic agents that has given birth to the recently published American Diabetes Association/European Association for the Study of Diabetes consensus statement recommending sodium-glucose cotransporter-2 inhibitors (SGLT2i) and glucagon like peptide-1 receptor agonists (GLP-1RA) in patients with T2DM and established CVD. As a result of over a decade of randomized placebo controlled cardiovascular outcome trials, the aforementioned drugs have received FDA approval for risk reduction of cardiovascular (CV) events in patients with T2DM and established CV disease. SGLT2i have been shown to have a stronger benefit in patients with congestive heart failure and diabetic kidney disease when compared to their GLP-1RA counterparts. These benefits are not withstanding additional considerations such as cost and the multiple FDA Black Box warnings. This topic is currently an emerging research area and this mini-review paper examines the role of these two novel classes of drugs in patients with T2DM with both confirmed, and at risk for, CVD.

Effect of tocilizumab, an interleukin-6 inhibitor, on early stage streptozotocin-induced diabetic nephropathy in rats

The aim of this study was to examine the effect of tocilizumab, an interleukin-6 (IL-6) inhibitor on streptozotocin-induced diabetic nephropathy. Male Sprague-Dawley rats (n = 36) were distributed into six groups and treated for 4 weeks. Groups 1, 3, 5 received either saline, tocilizumab (2 mg/kg), or tocilizumab (8 mg/kg) injection intraperitoneally (i.p.), every 2 weeks, respectively. Groups 2, 4, 6 were rendered diabetic by a single i.p. injection of streptozotocin (65 mg/kg) and were treated as in groups 1, 3, 5, respectively. Biochemical parameters were measured in plasma, urine, and kidneys. In the untreated diabetic group, there was a significant decrease in body weight, polyuria, and increased kidney weight. There was increased urinary albumin/creatinine ratio (UACR) and N-acetyl-β-D-glucosaminidase (NAG)/creatinine ratio (UNCR). Streptozotocin also induced a significant increase in creatinine clearance. In addition, diabetes was associated with increased oxidative stress [reduced renal glutathione reductase (GR), superoxide dismutase (SOD), catalase activities, and increased malondialdhyde (MDA)] and increased plasma tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and nitric oxide (NO) concentrations. Kidneys from streptozotocin-treated rats showed marked vacuolation of the proximal tubular epithelium with focal tubular necrosis and the glomeruli showing increase in mesangial cells. Tocilizumab significantly mitigated the increase in UACR and UNCR, renal MDA, plasma TNF-α, IL-6 and NO levels, and the decrease in renal SOD and catalase activities in diabetic rats. Tocilizumab did not significantly improve creatinine clearance; however, it attenuated the histopathological changes induced by streptozotocin. This study shows that tocilizumab was able to ameliorate some of the changes seen in streptozotocin-induced early diabetic nephropathy in rats. This is mainly due to its anti-inflammatory and antioxidative effects.

SGLT2 inhibitors and cardioprotection: a matter of debate and multiple hypotheses

Sodium-glucose co-transporter 2 (SGLT2) inhibitors inhibit glucose re-absorption in the proximal renal tubules. Two trials have shown significant reductions of cardiovascular (CV) events with empagliflozin and canagliflozin, which could not be attributed solely to their antidiabetic effects. The aim of the review is the critical presentation of suggested mechanisms/hypotheses for the SGLT2 inhibitors' cardioprotection. The search of the literature revealed many possible cardioprotective mechanisms, because SGLT2 inhibitors (i) increase natriuresis and act as diuretics with unique properties leading to a reduction in preload and myocardial stretch (the diuretic hypothesis); (ii) decrease blood pressure and afterload (the blood pressure lowering hypothesis), (iii) favor the production of ketones, which can act as a 'superfuel' in the cardiac and renal tissue (the 'thrifty substrate' hypothesis), (iv) improve many metabolic variables (the metabolic effects hypothesis), (v) exert many anti-inflammatory effects (the anti-inflammatory effects hypothesis), (vi) can act through the angiotensin II type II receptors in the context of simultaneous renin-angiotensin-aldosterone-system (RAAS) blockade leading to vasodilation and positive inotropic effects (the RAAS hypothesis), (vii) directly decrease the activity of the upregulated in heart failure Na⁺-H⁺ exchanger in myocardial cells leading to restoration of mitochondrial calcium handling in cardiomyocytes (the sodium hypothesis). Additionally, some SGLT2 inhibitors exhibit also SGLT1 inhibitory action possibly resulting in an attenuation of oxidative stress in ischemic myocardium (the SGLT1 inhibition hypothesis). Thus, many mechanisms have been suggested (and possibly act cumulatively) for the cardioprotective effects of SGLT2 inhibitors.

A Quantitative Systems Pharmacology Kidney Model of Diabetes Associated Renal Hyperfiltration and the Effects of SGLT Inhibitors

The early stage of diabetes mellitus is characterized by increased glomerular filtration rate (GFR), known as hyperfiltration, which is believed to be one of the main causes leading to renal injury in diabetes. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have been shown to be able to reverse hyperfiltration in some patients. We developed a mechanistic computational model of the kidney that explains the interplay of hyperglycemia and hyperfiltration and integrates the pharmacokinetics/pharmacodynamics (PK/PD) of the SGLT2i dapagliflozin. Based on simulation results, we propose kidney growth as the necessary process for hyperfiltration progression. Further, the model indicates that renal SGLT1i could significantly improve hyperfiltration when added to SGTL2i. Integrated into a physiologically based PK/PD (PBPK/PD) Diabetes Platform, the model presents a powerful tool for aiding drug development, prediction of hyperfiltration risk, and allows the assessment of the outcomes of individualized treatments with SGLT1-inhibitors and SGLT2-inhibitors and their co-administration with insulin.

The angiotensin II type 2 receptors protect renal tubule mitochondria in early stages of diabetes mellitus

Diabetic nephropathy correlates more closely to defective mitochondria and increased oxidative stress in the kidney than to hyperglycemia. A key driving factor of diabetic nephropathy is angiotensin II acting via the G-protein-coupled cell membrane type 1 receptor. The present study aimed to investigate the role of the angiotensin II type 2 receptor (AT2R) at the early stages of diabetic nephropathy. Using receptor binding studies and immunohistochemistry we found that the mitochondria in renal tubules contain high-affinity AT2Rs. Increased renal mitochondrial AT2R density by transgenic overexpression was associated with reduced superoxide production of isolated mitochondria from non-diabetic rats. Streptozotocin-induced diabetes (28 days) caused a drop in the ATP/oxygen ratio and an increase in the superoxide production of isolated renal mitochondria from wild-type diabetic rats. This correlated with changes in the renal expression profile and increased tubular epithelial cell proliferation. AT2R overexpression in tubular epithelial cells inhibited all diabetes-induced renal changes including a drop in mitochondrial bioenergetics efficiency, a rise in mitochondrial superoxide production, metabolic reprogramming, and increased proliferation. Thus, AT2Rs translocate to mitochondria and can contribute to reno-protective effects at early stages of diabetes. Hence, targeted AT2R overexpression in renal cells may open new avenues to develop novel types of drugs preventing diabetic nephropathy.

Protective effects of (-)-epicatechin and the colonic metabolite 3,4-dihydroxyphenylacetic acid against glucotoxicity-induced insulin signalling blockade and altered glucose uptake and production in renal tubular NRK-52E cells

Glucotoxicity (high levels of glucose) is a major cause in the pathogenesis of diabetes. Evidences indicate that (-)-epicatechin (EC) and colonic metabolites derived from flavonoid intake could possess antidiabetic effects, but the mechanisms for their preventive activities related to glucose homeostasis and insulin signalling in the kidney remain largely unknown. This work is aimed to investigate the effect of EC and main colonic phenolic acids derived from flavonoid intake, i.e. 2,3-dihydroxybenzoic-acid, 3,4-dihydroxyphenylacetic-acid (DHPAA) and 3-hydroxyphenylpropionic-acid, on insulin signalling, and glucose production and uptake in renal tubular proximal NRK-52E cells treated with high glucose. Pre-treatment with EC or DHPAA prevented the decreased tyrosine-phosphorylated and total levels of IR caused by high glucose. EC and DHPAA pre-treatment also avoided the inactivation of the PI3K/AKT pathway and AMPK, and the elevation of PEPCK levels induced by high glucose. Additionally, EC and DHPAA pre-treatment alleviated the altered glucose uptake and production caused by high glucose, although this protective effect was abrogated when AKT and AMPK were inhibited. These results suggest EC and DHPAA prevent or delay a potential dysfunction of NRK-52E cells treated with high glucose through the attenuation of the insulin signalling blockade and the modulation of glucose homeostasis via AKT and AMPK.

Renal protective effect of SGLT2 inhibitor dapagliflozin alone and in combination with irbesartan in a rat model of diabetic nephropathy

Considering the complementary mechanisms of SGLT2 inhibitors and angiotensin inhibitors on kidney, it is postulated that combination of both agents could afford greater protection against diabetic renal injury. So, we investigated renal protective effects of SGLT2 inhibitor, dapagliflozin, alone and in combination with irbesartan in a rat model of diabetic nephropathy. Diabetic rats, injected with nicotinamide-streptozotocin, were treated orally for 12 weeks with either vehicle, dapagliflozin 2 mg/kg/day, irbesartan 30 mg/kg/day, or combination of both drugs; respectively. Biochemical analysis included blood glucose, HbA1c, urinary albumin excretion, creatinine clearance, TGF-β1, sRAGE, oxidative markers, and histopathological examination of kidneys. Treatment with dapagliflozin, irbesartan, and especially their combination, produced significant reduction in albuminuria, improved renal function parameters, increased sRAGE level and improved inflammatory and oxidative markers, together with amelioration of renal histopathological changes. Beside glycemic control, dapagliflozin produced higher sRAGE levels than irbesartan, suggesting that inhibition of AGE-RAGE axis is important in its renoprotective action. Combination of dapagliflozin and irbesartan produced more remarkable protective effects on renal function and structure, than use of either agent alone. It is concluded that, combination of SGLT2 inhibitor, dapagliflozin and ARB, irbesartan could offer more effective renal protection and represent a promising therapeutic option for management of diabetic nephropathy.

Evaluation of diphenhydramine in talc induced type 2 diabetes mellitus in Wistar rats

Evaluation of diphenhydramine in talc induced type 2 diabetes mellitus was done in Wistar rats. Oral administration of Talc (10mg/kg)carried out for 21days increased the levels of serum glutamate pyruvate transaminase (SGPT), glutamate oxaloacetate transaminase (SGOT), serum creatinine, blood glucose, urea, uric acid and triglycerides (TGs), but when the animals were treated with diphenhydramine (DPH), the levels of the aforementioned biochemical parameters decreased significantly (p<0.0001). The level of serum cholesterol and high density lipoprotein (HDL) was found to be reduced in Diabetes Mellitus (DM) control and when it was treated with DPH control animals, these makers increased significantly. The study done on DM and Diphenhydramine suggests that Talc increases the blood glucose level at a dose of 10mg/kg (0.14gm) and Diphenhydramine (1mg/kg)reduces the increased blood glucose level. These finding simply that diphenhydramine may be useful in the management of talc induced diabetes.