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

Tanshinone IIA Promoted Autophagy and Inhibited Inflammation to Alleviate Podocyte Injury in Diabetic Nephropathy

Purpose

Tanshinone IIA (Tan-IIA) is widely used in patients with diabetic nephropathy (DN), but its protective effect on podocytes in DN has not been well studied. In this study, the effects of Tan-IIA on autophagy and inflammation of glomerular podocytes in DN were observed in vivo and in vitro, and the underlying mechanisms were investigated. Irbesartan, an angiotensin II receptor blocker, is a representative medication for the clinical treatment of DN. So irbesartan was chosen as a positive control drug.

Methods

Eight-week-old male db/db mice were randomly divided into a DN group, an irbesartan group, and three groups receiving different doses of Tan-IIA. The control group consisted of the db/m littermate mice. Blood, urine, and kidney samples were taken from the mice after 12 weeks of continuous administration. Renal protection of Tan-IIA was evaluated using enzyme-linked immunosorbent assay kits, haematoxylin and eosin staining, transmission electron microscopy, Western blotting, and immunohistochemistry. In vitro, the protective effect of Tan-IIA on podocytes was explored using MPC5 cells cultured with high glucose.

Results

Tan-IIA significantly improved renal pathological injury and relieved the renal dysfunction in DN. Compared with the DN group, Tan-IIA could up-regulate the expression of Synaptopodin, Podocin, LC3II/I and Beclin-1 (p < 0.05), and down-regulate the expression of p62, F4/80, NF-κB p65, IL-1β, TNF-α and IL-6 (p < 0.05) both in vivo and in vitro, suggesting that Tan-IIA treatment alleviated podocyte injury by promoting autophagy and inhibiting inflammation during DN. The levels of p-PI3K/PI3K, p-Akt/Akt and p-mTOR/mTOR in Tan-IIA group were lower than those in DN group (p < 0.05), indicating that Tan-IIA inhibited the PI3K/Akt/mTOR signalling pathway in podocytes, which was a key pathway in regulating both autophagy and inflammation.

Conclusion

Tan-IIA prevented podocyte injury in DN by fostering autophagy and inhibiting inflammation, at least in part via inhibition of the PI3K/Akt/mTOR signalling pathway.

Renal handling of albumin in rats with early stage diabetes: A theoretical analysis

In early diabetic nephropathy (DN), recent studies have shown that albuminuria stems mostly from alterations in tubular function rather than from glomerular damage. Several factors in DN, including hyperfiltration, hypertrophy and reduced abundance of the albumin receptors megalin and cubilin, affect albumin endocytosis in the proximal tubule (PT). To assess their respective contribution, we developed a model of albumin handling in the rat PT that couples the transport of albumin to that of water and solutes. Our simulations suggest that, under basal conditions, ∼75% of albumin is retrieved in the S1 segment. The model predicts negligible uptake in S3, as observed experimentally. It also accurately predicts the impact of acute hyperglycaemia on urinary albumin excretion. Simulations reproduce observed increases in albumin excretion in early DN by considering the combined effects of increased glomerular filtration rate (GFR), osmotic diuresis, hypertrophy, and megalin and cubilin downregulation, without stipulating changes in glomerular permselectivity. The results indicate that in isolation, glucose-elicited osmotic diuresis and glucose transporter upregulation raise albumin excretion only slightly. Enlargement of PT diameter not only augments uptake via surface area expansion, but also reduces fluid velocity and thus shear stress-induced stimulation of endocytosis. Overall, our model predicts that downregulation of megalin and cubilin and hyperfiltration both contribute significantly to increasing albumin excretion in rats with early-stage diabetes. The results also suggest that acute sodium-glucose cotransporter 2 inhibition lowers albumin excretion only if GFR decreases sufficiently, and that angiotensin II receptor blockers mitigate urinary albumin loss in early DN in large part by upregulating albumin receptor abundance. KEY POINTS: The urinary excretion of albumin is increased in early diabetic nephropathy (DN). It is difficult to experimentally disentangle the multiple factors that affect the renal handling of albumin in DN. We developed a mathematical model of albumin transport in the rat proximal tubule (PT) to examine the impact of elevated plasma glucose, hyperfiltration, PT hypertrophy and reduced abundance of albumin receptors on albumin uptake and excretion in DN. Our model predicts that glucose-elicited osmotic diuresis per se raises albumin excretion only slightly. Conversely, increases in PT diameter and length favour reduced albumin excretion. Our results suggest that downregulation of the receptors megalin and cubilin in PT cells and hyperfiltration both contribute significantly to increasing albumin excretion in DN. The model helps to better understand the mechanisms underlying urinary loss of albumin in early-stage diabetes, and the impact of specific treatments thereupon.

A Study to Evaluate the Effect of Sodium-Glucose Co-transporter 2 (SGLT2) Inhibitors on Oxidative Stress Parameters in Type 2 Diabetes Mellitus Patients

Introduction Diabetes mellitus (DM) is a global health issue with 50 million diabetics currently residing in India. Hyperglycemia causes tissue damage due to mitochondrial overproduction of reactive oxygen species. Sodium-glucose cotransporter-2 (SGLT2) inhibitors (SGLT2i) have shown a decrease in oxidative stress by either amelioration of free-radical generation or potentiation of cellular antioxidative capacity in preclinical studies. However, there is a paucity of published clinical studies. Hence, this study was undertaken to evaluate the effect of co-administration of SGLT2i with other drugs on oxidative stress in type 2 DM (T2DM) patients. Methods A prospective, parallel, open-label study in T2DM patients attending endocrinology OPD was conducted for a period of 12 months. At the clinician's discretion, patients were grouped as SGLT2i as an add-on to standard drugs vs standard drugs alone. Blood samples were collected at baseline and at the end of 12 weeks to estimate malondialdehyde (MDA), nitric oxide (NO), and glutathione (GSH) levels. Secondary parameters - glycemic indices and lipid profile - were estimated every four weeks. Results A total of 32 patients were enrolled in the study (16 per group). There was a significant decrease in MDA (p < 0.05) and NO (p < 0.01) and a highly significant increase in GSH (p < 0.001) at 12 weeks from baseline in the SGLT2i group. A reduction in fasting blood sugar (FBS) and post-prandial blood sugar (PPBS) and a 0.56% difference in HbA1c were also noted in the SGLT2i group. Significant lowering of low-density lipoprotein (LDL, p < 0.05) and elevation in HDL levels (p < 0.05) from baseline was seen in the SGLT2i group.  Conclusion Co-administration of SGLT2i with antidiabetic drugs demonstrated a significant effect in improving oxidative stress biomarkers and glycemic and lipid profiles among T2DM patients.

Benefits and risks of drug combination therapy for diabetes mellitus and its complications: a comprehensive review

Diabetes is a chronic metabolic disease, and its therapeutic goals focus on the effective management of blood glucose and various complications. Drug combination therapy has emerged as a comprehensive treatment approach for diabetes. An increasing number of studies have shown that, compared with monotherapy, combination therapy can bring significant clinical benefits while controlling blood glucose, weight, and blood pressure, as well as mitigating damage from certain complications and delaying their progression in diabetes, including both type 1 diabetes (T1D), type 2 diabetes (T2D) and related complications. This evidence provides strong support for the recommendation of combination therapy for diabetes and highlights the importance of combined treatment. In this review, we first provided a brief overview of the phenotype and pathogenesis of diabetes and discussed several conventional anti-diabetic medications currently used for the treatment of diabetes. We then reviewed several clinical trials and pre-clinical animal experiments on T1D, T2D, and their common complications to evaluate the efficacy and safety of different classes of drug combinations. In general, combination therapy plays a pivotal role in the management of diabetes. Integrating the effectiveness of multiple drugs enables more comprehensive and effective control of blood glucose without increasing the risk of hypoglycemia or other serious adverse events. However, specific treatment regimens should be tailored to individual patients and implemented under the guidance of healthcare professionals.

Role of canagliflozin in ameliorating isoprenaline induced cardiomyocyte oxidative stress via the heme oxygenase-1 mediated pathway

Canagliflozin (CZ) is commonly prescribed for management of type-2 diabetes mellitus (T2DM); it also can reduce the risk of myocardial infarction. We used 80 albino Wistar rats to investigate the cardioprotective potential of CZ against oxidative stress caused by administration of isoprenaline (ISO). We found that ISO stimulates production of reactive oxygen species and that CZ administration caused up-regulation of antioxidants and down-regulation of oxidants due to nuclear factor erythroid-2 related factor-2, as well as by enhancement of the heme oxygenase-1 mediated cascade. CZ monotherapy may play a cardioprotective role in diabetic patients. CZ possesses strong antioxidant potential that ameliorates cardiac damage induced by ISO administration.

Promising renoprotective effect of gold nanoparticles and dapagliflozin in diabetic nephropathy via targeting miR-192 and miR-21

Diabetic nephropathy (DN) is a worldwide issue that eventually leads to end-stage renal failure, with limited therapeutic options. Prior research has revealed that gold nanoparticles (AuNPs) have a substantial antidiabetic impact. In addition, sodium-glucose cotransporter2 (SGLT2) inhibitors, including dapagliflozin (DAPA), had renoprotective impact on DN. Therefore, this research attempted to determine the potential AuNPs and DAPA impacts in ameliorating experimentally DN induction and the underlying mechanisms focusing on miR-192 and miR-21, correlating them with autophagy, apoptosis, fibrosis, and oxidative stress. Diabetes induction was through a single intraperitoneal streptozotocin (55 mg/kg) injection, and rats with diabetes received AuNPs (2.5 mg/kg/day) as well as DAPA (2 mg/kg/day) for 7 weeks as a treatment. AuNPs and DAPA treatment for 7 weeks substantially alleviated DN. AuNPs and DAPA significantly increased catalase (CAT) activity as well as serum total antioxidant capacity (TAC), along with a substantial decline in malondialdehyde (MDA). AuNPs and DAPA treatment alleviated renal fibrosis as they decreased transforming growth factorß1(TGF-ß1) as well as matrix metalloproteinase-2 (MMP-2) renal expression, decreased apoptosis through alleviating the proapoptotic gene (caspase-3) renal expression and increased the antiapoptotic gene (Bcl-2) renal expression, and increased autophagy as they increased LC-3 as well as Beclin-1 renal expression. Autophagy activation, inhibition of apoptosis, and renal fibrosis could be due to their inhibitory impact on miR-192 and miR-21 renal expression. AuNPs and DAPA have a protective effect on DN in rats by targeting miR-192 and miR-21 and their downstream pathways, including fibrosis, apoptosis, autophagy, and oxidative stress.

A systematic review on renal effects of SGLT2 inhibitors in rodent models of diabetic nephropathy

We have performed a systematic review of studies reporting on the renal effects of SGLT2 inhibitors in rodent models of diabetes. In 105 studies, SGLT2 inhibitors improved not only the glycemic control but also various aspects of renal function in most cases. These nephroprotective effects were similarly reported whether treatment with the SGLT2 inhibitor started concomitant with the onset of diabetes (within 1 week), early after onset (1-4 weeks) or after nephropathy had developed (>4 weeks after onset) with the latter probably having the greatest translational value. They were observed across various animal models of type 1 and type 2 diabetes/obesity (4 and 23 models, respectively), although studies in the type 2 diabetes model of db/db mice more often had negative data than in other models. Among possibly underlying pathophysiological mechanisms of nephroprotection, treatment with SGLT2 inhibitors had beneficial effects on lipid metabolism, blood pressure, glomerulosclerosis as well as renal tubular fibrosis, apoptosis, oxidative stress, and inflammation. These pathomechanisms highly influence atherosclerosis and renal health, which are two major factors that lead to an enhanced mortality in patients with diabetes and/or chronic kidney disease. Interestingly, renal SGLT2 inhibitor effects did not always correlate with those on glucose homeostasis, particularly in a limited number of direct comparative studies with other anti-diabetic treatments, indicating that nephroprotection may at least partly occur by mechanisms other than improving glycemic control. Our analyses did not provide evidence for different nephroprotective efficacy between SGLT2 inhibitors. Importantly, only four of 105 studies reported on female animals, and none provided direct comparative data between sexes. We conclude that more data on female animals and more direct comparative studies with other anti-diabetic compounds and combinations of treatments are needed.

Sodium-glucose cotransporter inhibitors and kidney fibrosis: review of the current evidence and related mechanisms

Sodium-glucose cotransporter inhibitors (SGLT2i) are a new class of anti-diabetic drugs that have beneficial cardiovascular and renal effects. These drugs decrease proximal tubular glucose reabsorption and decrease blood glucose levels as a main anti-diabetic action. Furthermore, SGLT2i decreases glomerular hyperfiltration by a tubuloglomerular feedback mechanism. However, the renal benefits of these agents are independent of glucose-lowering and hemodynamic factors, and SGLT2i also impacts the kidney structure including kidney fibrosis. Renal fibrosis is a common pathway and pathological marker of virtually every type of chronic kidney disease (CKD), and amelioration of renal fibrosis is of utmost importance to reduce the progression of CKD. Recent studies have shown that SGLT2i impact many cellular processes including inflammation, hypoxia, oxidative stress, metabolic functions, and renin-angiotensin system (RAS) which all are related with kidney fibrosis. Indeed, most but not all studies showed that renal fibrosis was ameliorated by SGLT2i through the reduction of inflammation, hypoxia, oxidative stress, and RAS activation. In addition, less known effects on SGLT2i on klotho expression, capillary rarefaction, signal transducer and activator of transcription signaling and peptidylprolyl cis/trans isomerase (Pin1) levels may partly explain the anti-fibrotic effects of SGLT2i in kidneys. It is important to remember that some studies have not shown any beneficial effects of SGLT2i on kidney fibrosis. Given this background, in the current review, we have summarized the studies and pathophysiologic aspects of SGL2 inhibition on renal fibrosis in various CKD models and tried to explain the potential reasons for contrasting findings.

Role of hypoxia inducible factor/vascular endothelial growth factor/endothelial nitric oxide synthase signaling pathway in mediating the cardioprotective effect of dapagliflozin in cyclophosphamide-induced cardiotoxicity

BACKGROUND

Cyclophosphamide (CP) is a commonly used chemotherapeutic and immunosuppressive alkylating agent. However, cardiac adverse effects of CP interfere with its clinical benefit. Cardio-oncology research is currently an important issue and finding effective cardiopreserving agents is a critical need. For the first time, we aimed to detect if dapagliflozin (DAP) could ameliorate CP-induced cardiac injury and investigated the role of hypoxia inducible factor α (HIF1α)/vascular endothelial growth factor (VEGF)/endothelial nitric oxide synthase (eNOS) pathway.

METHODS

Forty male Wistar albino rats were included in the current model. Studied groups are: control group; CP-induced cardiotoxicity group; CP group treated with DAP; CP group treated with DAP and administered a nitric oxide synthase inhibitor; nitro-ω-L-arginine (L-NNA) before DAP to explore the role of eNOS.

RESULTS

Our data revealed that CP could induce cardiac damage as manifested by significant increases in cardiac enzymes, blood pressure, malondialdehyde (MDA), tumor necrosis factor alpha (TNFα), HIF1α, sodium glucose co-transporter 2 (SGLT2) and cleaved caspase-3 levels with toxic histopathological changes. However, there are significant decreases in reduced glutathione (GSH), total antioxidant capacity (TAC), VEGF, and eNOS. On the opposite side, co-administration of DAP showed marked improvement of CP-induced cardiac damage that may be due to its ability to inhibit SGLT2, antioxidant, anti-inflammatory and anti-apoptotic properties. Results showed decreasing the cardioprotective effect of DAP on administration of L-NNA, reflecting the critical effect of eNOS in mediating such protection.

CONCLUSION

DAP could reduce CP cardiotoxicity based upon its ability to modulate SGLT2 and HIF1α/VEGF/eNOS signaling pathway.

Repurposing SGLT2 Inhibitors for Neurological Disorders: A Focus on the Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a substantially increasing incidence rate. It is characterized by repetitive behavior, learning difficulties, deficits in social communication, and interactions. Numerous medications, dietary supplements, and behavioral treatments have been recommended for the management of this condition, however, there is no cure yet. Recent studies have examined the therapeutic potential of the sodium-glucose cotransporter 2 (SGLT2) inhibitors in neurodevelopmental diseases, based on their proved anti-inflammatory effects, such as downregulating the expression of several proteins, including the transforming growth factor beta (TGF-β), interleukin-6 (IL-6), C-reactive protein (CRP), nuclear factor κB (NF-κB), tumor necrosis factor alpha (TNF-α), and the monocyte chemoattractant protein (MCP-1). Furthermore, numerous previous studies revealed the potential of the SGLT2 inhibitors to provide antioxidant effects, due to their ability to reduce the generation of free radicals and upregulating the antioxidant systems, such as glutathione (GSH) and superoxide dismutase (SOD), while crossing the blood brain barrier (BBB). These properties have led to significant improvements in the neurologic outcomes of multiple experimental disease models, including cerebral oxidative stress in diabetes mellitus and ischemic stroke, Alzheimer's disease (AD), Parkinson's disease (PD), and epilepsy. Such diseases have mutual biomarkers with ASD, which potentially could be a link to fill the gap of the literature studying the potential of repurposing the SGLT2 inhibitors' use in ameliorating the symptoms of ASD. This review will look at the impact of the SGLT2 inhibitors on neurodevelopmental disorders on the various models, including humans, rats, and mice, with a focus on the SGLT2 inhibitor canagliflozin. Furthermore, this review will discuss how SGLT2 inhibitors regulate the ASD biomarkers, based on the clinical evidence supporting their functions as antioxidant and anti-inflammatory agents capable of crossing the blood-brain barrier (BBB).

Unfavorable effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors on the skeletal system of nondiabetic rats

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a new class of antidiabetic drugs, acting by inhibiting the reabsorption of glucose in the kidneys. They turned out to improve cardiovascular and renal outcomes not only in patients with type 2 diabetes but also in nondiabetic patients. At present, they are more and more widely used in patients without diabetes. Since there were concerns that SGLT2 inhibitors may increase fracture risk in diabetes, the aim of the study was to examine the effect of dapagliflozin and canagliflozin on the musculoskeletal system of nondiabetic, healthy rats. The experiments were carried out on mature female rats, divided into the control rats and rats treated with dapagliflozin (1.4 mg/kg p.o.) or canagliflozin (4.2 mg/kg p.o.) for 4 weeks. Serum bone turnover markers, skeletal muscle strength and mass, bone mass, density, histomorphometric parameters and mechanical properties were determined. Administration of the drugs did not affect the skeletal muscle mass and strength. There was no effect on serum bone turnover markers, and bone mass and composition. However, administration of both drugs resulted in disorders of cancellous bone microarchitecture and worsening of bone mechanical properties. In conclusion, both SGLT2 inhibitors unfavorably affected the skeletal system of healthy rats.

The Nicotinamide/Streptozotocin Rodent Model of Type 2 Diabetes: Renal Pathophysiology and Redox Imbalance Features

Diabetic nephropathy (DN) is a common complication of diabetes mellitus. While there has been a great advance in our understanding of the pathogenesis of DN, no effective managements of this chronic kidney disease are currently available. Therefore, continuing to elucidate the underlying biochemical and molecular mechanisms of DN remains a constant need. In this regard, animal models of diabetes are indispensable tools. This review article highlights a widely used rodent model of non-obese type 2 diabetes induced by nicotinamide (NA) and streptozotocin (STZ). The mechanism underlying diabetes induction by combining the two chemicals involves blunting the toxic effect of STZ by NA so that only a percentage of β cells are destroyed and the remaining viable β cells can still respond to glucose stimulation. This NA-STZ animal model, as a platform for the testing of numerous antidiabetic and renoprotective materials, is also discussed. In comparison with other type 2 diabetic animal models, such as high-fat-diet/STZ models and genetically engineered rodent models, the NA-STZ model is non-obese and is less time-consuming and less expensive to create. Given that this unique model mimics certain pathological features of human DN, this model should continue to find its applications in the field of diabetes research.

Renoprotective effects of dapagliflozin in an iron overload non-diabetic rat model

PURPOSE

Sodium glucose co-transporter (SGLT) 2 inhibitors are oral anti-diabetic drugs with proven kidney protective effects. Renal protective effects in non-diabetic individuals have also been shown in recent studies. The aim of this study was to determine the renal protective effects of dapagliflozin by evaluating the oxidative stress markers in the kidney tissue and demonstrating it in renal histological sections in an iron-overloaded rat model.

METHODS

A total of 24 Wistar Albino rats were separated into 3 groups of 8 rats. Iron sucrose (60 ​mg/kg/day) was administered intraperitoneally to the first group (Group Fe) (n ​= ​8), iron sucrose and dapagliflozin (0.1 ​mg/kg/day) to the second group (Group Fe ​+ ​D) (n ​= ​8) and intraperitoneal saline as placebo to the control group (Group C) (n ​= ​8) for 4 weeks. The glomerular changes were semi-quantitatively scored with Oxford Classification. Oxidative stress was analyzed from the tissue fluorescent oxidation product (FLOP), malondialdehyde (MDA) and total sulfhydryl (T-SH) levels.

RESULTS

Dapagliflozin prevented glomerular and mesangial damage of iron overload in the non-diabetic rat model. MDA levels were significantly higher in Group Fe compared to the Group C, and there was no significant difference between the Fe ​+ ​D group and Group C. T-SH levels were preserved in the Fe ​+ ​D group and were significantly higher than in the Fe group.

CONCLUSIONS

The results of this study showed that dapagliflozin helped preserve the glomerular and mesangial structure histologically and reduced oxidative stress markers in a non-diabetic iron overload rat model.

SGLT2 Inhibition in Type 1 Diabetes with Diabetic Kidney Disease: Potential Cardiorenal Benefits Can Outweigh Preventable Risk of Diabetic Ketoacidosis

PURPOSE OF REVIEW

The aim of this review is to summarize existing research investigating the use of sodium glucose cotransporter-2 (SGLT2) inhibitors in patients with type 1 diabetes mellitus (T1DM) while highlighting potential strategies to mitigate the risk of diabetic ketoacidosis (DKA).

RECENT FINDINGS

SGLT2 inhibitors have been studied in patients with T1DM in phase 3 clinical trials such as the inTandem, DEPICT, and EASE trials, which demonstrated consistent reductions in HbA1c. Secondary analyses of these trials have also reported potential kidney protective effects that are independent of improved glycemic control. However, trials in patients with type 2 diabetes mellitus (T2DM) have found an increased risk of DKA with SGLT2 inhibitors, a serious concern in patients with T1DM. SGLT2 inhibitors provide cardiovascular benefits and kidney protection in patients with T2DM and are a promising therapeutic option for patients with T1DM due to overlapping pathophysiological mechanisms. However, SGLT2 inhibitors increase the risk of DKA, and there is currently a lack of research investigating the beneficial effects of SGLT2 inhibitors in patients with T1DM. Preventative measure for DKA would have to be implemented and the risks would need to be carefully balanced with the benefits offered by SGLT2 inhibitors. Additional research will also be required to determine the kidney protective effects of SGLT2 inhibitors in patients with T1DM and diabetic kidney disease and to quantify the risk of DKA after the implementation of preventative measures, proper patient education, and ketone monitoring.

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.

Sodium-glucose Cotransporter Type 2 Inhibitors: A New Insight into the Molecular Mechanisms of Diabetic Nephropathy

Diabetic nephropathy is one of the chronic microvascular complications of diabetes and is a leading cause of end-stage renal disease. Fortunately, clinical trials have demonstrated that sodium-glucose cotransporter type 2 inhibitors could decrease proteinuria and improve renal endpoints and are promising agents for the treatment of diabetic nephropathy. The renoprotective effects of sodium-glucose cotransporter type 2 inhibitors cannot be simply attributed to their advantages in aspects of metabolic benefits, such as glycemic control, lowering blood pressure, and control of serum uric acid, or improving hemodynamics associated with decreased glomerular filtration pressure. Some preclinical evidence suggests that sodium-glucose cotransporter type 2 inhibitors exert their renoprotective effects by multiple mechanisms, including attenuation of oxidative and endoplasmic reticulum stresses, anti-fibrosis and anti-inflammation, protection of podocytes, suppression of megalin function, improvement of renal hypoxia, restored mitochondrial dysfunction and autophagy, as well as inhibition of sodium-hydrogen exchanger 3. In the present study, the detailed molecular mechanisms of sodium-glucose cotransporter type 2 inhibitors with the actions of diabetic nephropathy were reviewed, with the purpose of providing the basis for drug selection for the treatment of diabetic nephropathy.

Effect of dual inhibition of DPP4 and SGLT2 on tacrolimus-induced diabetes mellitus and nephrotoxicity in a rat model

Sodium/glucose co-transporter-2 inhibitor (SGLT2i) or dipeptidyl peptidase IV inhibitor (DPP4i) is a newer anti-diabetic drug in type II diabetes mellitus (DM), but their use in tacrolimus (TAC)-induced DM is still undetermined. We performed this study to evaluate the effect of these two drugs in TAC-induced DM and nephrotoxicity in ex vivo and in vivo. In the experimental Sprague Dawley rat model of TAC-induced DM and nephrotoxicity, dual inhibition of DPP4 and SGLT2 significantly decreased blood glucose level, HbA1C and increased plasma insulin levels and pancreatic islet size compared with each drug. In the kidney, dual inhibition improved renal function decreased interstitial fibrosis and profibrotic cytokines compared with DPP4i and SGLT2i alone. Increased oxidative stress by TAC was remarkably decreased with DPP4i or SGLT2i in serum, pancreatic and renal tissues and this decrease was much more significant in the combination group. In in vitro study, TAC decreased the cell viability of human kidney-2(HK-2) cells and insulin-secreting beta-cell-derived line(INS-1) cells. SGLT2i protected TAC-induced cell death in HK-2 cells, but not in INS-1 cells. The addition of DPP4i to SGLT2i compensated for a lack of protective effect of SGLT2i on INS-1 cells. This finding provides the rationale for the combined treatment of SGLG2i and DPP4i in TAC-induced DM and nephrotoxicity.

SGLT2 inhibition effect on salt-induced hypertension, RAAS, and Na+ transport in Dahl SS rats

Na+-glucose cotransporter-2 (SGLT2) inhibitors are the new mainstay of treatment for diabetes mellitus and cardiovascular diseases. Despite the remarkable benefits, the molecular mechanisms mediating the effects of SGLT2 inhibitors on water and electrolyte balance are incompletely understood. The goal of this study was to determine whether SGLT2 inhibition alters blood pressure and kidney function via affecting the renin-angiotensin-aldosterone system (RAAS) and Na+ channels/transporters along the nephron in Dahl salt-sensitive rats, a model of salt-induced hypertension. Administration of dapagliflozin (Dapa) at 2 mg/kg/day via drinking water for 3 wk blunted the development of salt-induced hypertension as evidenced by lower blood pressure and a left shift of the pressure natriuresis curve. Urinary flow rate, glucose excretion, and Na+- and Cl--to-creatinine ratios increased in Dapa-treated compared with vehicle-treated rats. To define the contribution of the RAAS, we measured various hormones. Despite apparent effects on Na+- and Cl--to-creatinine ratios, Dapa treatment did not affect RAAS metabolites. Subsequently, we assessed the effects of Dapa on renal Na+ channels and transporters using RT-PCR, Western blot analysis, and patch clamp. Neither mRNA nor protein expression levels of renal transporters (SGLT2, Na+/H+ exchanger isoform 3, Na+-K+-2Cl- cotransporter 2, Na+-Cl- cotransporter, and α-, β-, and γ-epithelial Na+ channel subunits) changed significantly between groups. Furthermore, electrophysiological experiments did not reveal any difference in Dapa treatment on the conductance and activity of epithelial Na+ channels. Our data suggest that SGLT2 inhibition in a nondiabetic model of salt-sensitive hypertension blunts the development of salt-induced hypertension by causing glucosuria and natriuresis without changes in the RAAS or the expression or activity of the main Na+ channels and transporters.NEW & NOTEWORTHY The present study indicates that Na+-glucose cotransporter-2 (SGLT2) inhibition in a nondiabetic model of salt-sensitive hypertension blunts the development and magnitude of salt-induced hypertension. Chronic inhibition of SGLT2 increases glucose and Na+ excretion without secondary effects on the expression and function of other Na+ transporters and channels along the nephron and hormone levels in the renin-angiotensin-aldosterone system. These data provide novel insights into the effects of SGLT2 inhibitors and their potential use in hypertension.

Dapagliflozin improves steatohepatitis in diabetic rats via inhibition of oxidative stress and inflammation

Type-2 diabetes mellitus and NAFLD are considered as one of the greatest worldwide metabolic disorders with growing incidence. It was found that patients with T2DM have two-fold increase to develop NAFLD. Evidence that some antidiabetic agents improve NAFLD/NASH in patients with T2DM is evolving. However, there are no certain pharmacologic therapies. The current study aimed to investigate the underlying mechanisms for the hepatoprotective effect of dapagliflozin against steatohepatitis in diabetic rats. Type-2 diabetes was induced by HFD followed by a single dose of STZ (30 mg/kg I.P). Fifty rats were randomly divided into 5 groups: Group1; normal control, Group 2; diabetic control, Groups (3-5); diabetic rats received daily dapagliflozin (0.75, 1.5, 3 mg/kg, p.o.) respectively for 6 weeks. At the end of the experiment, blood glucose level and serum insulin were measured. Hepatic tissue homogenization was performed for measuring inflammatory and oxidative stress markers. In addition, histopathological investigation of the hepatic tissue was done. Diabetic rats exhibited remarkable increase in liver weight and liver enzymes, along with histopathological changes, significant elevation in MDA, IL-1 β, TGFβ levels and, NF-κB, alpha-SMA expressions. Dapagliflozin treatment decreased liver weight, liver enzymes, together with marked improvement in histopathological changes. Furthermore, dapagliflozin increased antioxidant enzymes, GSH levels. Interestingly, Dapagliflozin reduced IL-1 β, TGFβ levels and, NF-κB, alpha-SMA expressions. Present data show that dapagliflozin represent a viable approach to protect the liver against diabetes-encouraged steatohepatitis through inhibiting oxidative stress, inflammation and fibrosis progression thus conserving liver function.

Exploring the Effect of Dapagliflozin on Alcoholic Kidney Injury and Renal Interstitial Fibrosis in Rats Based on TIMP-1/MMP-24 Pathway

Objective

To establish a rat model of alcoholic kidney injury and detect the expression of TIMP-1/MMP-24 in the kidneys of rats with alcoholic kidney injury at the molecular pathological level, so as to explore the mechanism of alcohol abuse leading to kidney injury and renal interstitial fibrosis as well as the alleviation of alcohol-induced kidney injury and inhibition of renal interstitial fibrosis by dapagliflozin.

Methods

48 male rats were randomly divided into 4 groups: control group, alcohol group, alcohol + dapagliflozin group, and alcohol + losartan group, each with 12 rats. Different drugs were administered by gavage for modeling and treatment. Six days later, the rats were sacrificed, blood was collected from the heart to separate the serum, and the blood creatinine (Scr) and urea nitrogen (BUN) contents were detected biochemically. After blood collection, the kidney tissue was taken and fixed in10% neutral formalin. The expression of renal tissue inflammatory factors (CRP, IL-6, and TNF-α) and renal fibrosis indexes (LN, HA, and TGF-β1) were detected; MMP-24 and TIMP-1 in the kidney tissue of rats in different treatment groups were detected, and Smad3 expression was also detected.

Results

After treatment, the general condition of the alcohol + dapagliflozin group and the alcohol + losartan group improved to different degrees. The weight first decreased and then gradually increased over time. There was no statistical difference in the weight change between the two groups; Compared with the control group, the Scr level, BUN content, renal index, inflammatory factors, and renal fibrosis indexes in the alcohol group were significantly increased (P < 0.05); after 6 weeks of treatment, in the alcohol + dapagliflozin group and alcohol + losartan group, Scr level, BUN content, kidney index, inflammatory factors, and renal fibrosis indexes were significantly decreased (P < 0.05); the expression of MMP-24 in the kidney tissue of the control group was upregulated, and the expression of TIMP-1 and Smad3 was downregulated; MMP-24 expression was downregulated, and TIMP-1 and Smad3 expression was significantly upregulated (P < 0.05) in the rats of the alcohol group. After dapagliflozin and losartan treatment, MMP-24 expression gradually increased and TIMP-1 and Smad3 expression gradually decreased (P < 0.05).

Conclusion

Long-term large-scale alcohol intake can cause kidney tissue damage and fibrotic lesions. The expression of fibrotic cytokines such as TIMP-1 and Smad3 will increase, and the expression of MMP-24 will be decreased. However, dapagliflozin and losartan have certain therapeutic effects on the abovementioned lesions. The mechanism may be downregulating TIMP-1 and Smad3 and upregulating the expression of MMP-24 and other cytokines in the kidney.

Effects of a 12-Month Treatment with Glucagon-like Peptide-1 Receptor Agonists, Sodium-Glucose Cotransporter-2 Inhibitors, and Their Combination on Oxidant and Antioxidant Biomarkers in Patients with Type 2 Diabetes

Imbalance between oxidative stress burden and antioxidant capacity is implicated in the course of atherosclerosis among type 2 diabetic patients. We addressed the effects of insulin, glucagon-like peptide-1 receptor agonists (GLP1-RA), sodium-glucose cotransporter-2 inhibitors (SGLT-2i), and their combination on levels of oxidant and antioxidant biomarkers. We recruited a total of 160 type 2 diabetics, who received insulin (n = 40), liraglutide (n = 40), empagliflozin (n = 40), or their combination (GLP-1RA+SGLT-2i) (n = 40). We measured at baseline, at 4 and at 12 months of treatment: (a) Thiobarbituric Acid Reactive Substances (TBARS), (b) Malondialdehyde (MDA), (c) Reducing Power (RP), (d) 2,2¢-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) radical (ABTS) and (e) Total Antioxidant Capacity TAC). Dual treatment resulted in significant improvement of TBARS, MDA, and ABTS at four months compared with the other groups (p < 0.05 for all comparisons). At twelve months, all participants improved TBARS, MDA, and ABTS (p < 0.05). At 12 months, GLP1-RA and GLP-1RA+SGLT2-i provided a greater reduction of TBARS (−8.76% and −9.83%) compared with insulin or SGLT2i (−0.5% and 3.22%), (p < 0.05). GLP1-RA and GLP-1RA+SGLT-2i showed a greater reduction of MDA (−30.15% and −31.44%) compared with insulin or SGLT2i (4.72% and −3.74%), (p < 0.05). SGLT2i and GLP-1RA+SGLT2-i showed increase of ABTS (12.87% and 14.13%) compared with insulin or GLP1-RA (2.44% and −3.44%), (p < 0.05). Only combined treatment resulted in increase of TAC compared with the other groups after 12 months of treatment (p < 0.05).12-month treatment with GLP1-RA and SGLT2i resulted in reduction of biomarkers responsible for oxidative modifications and increase of antioxidant biomarker, respectively. The combination treatment was superior and additive to each separate agent and also the beneficial effects appeared earlier.

The Role of SGLT2 Inhibitors in Vascular Aging

Vascular aging is defined as organic and functional changes in blood vessels, in which decline in autophagy levels, DNA damage, MicroRNA (miRNA), oxidative stress, sirtuin, and apoptosis signal-regulated kinase 1 (ASK1) are integral thereto. With regard to vascular morphology, the increase in arterial stiffness, atherosclerosis, vascular calcification and high amyloid beta levels are closely related to vascular aging. Further closely related thereto, at the cellular level, is the aging of vascular endothelial cells (ECs) and vascular smooth muscle cells (VSMCs). Vascular aging seriously affects the health, economy and life of patients, but can be delayed by SGLT2 inhibitors through the improvement of vascular function. In the present article, a review is conducted of recent domestic and international progress in research on SGLT2 inhibitors,vascular aging and diseases related thereto, thereby providing theoretical support and guidance for further revealing the relationship between SGLT2 inhibitors and diseases related to vascular aging.

Novel Anti-inflammatory and Anti-fibrotic Agents for Diabetic Kidney Disease-From Bench to Bedside

Chronic low-grade inflammation, now coined by the new paradigm as "metaflammation" or "metainflammation", has been linked to chronic kidney disease and its progression. In diabetes, altered metabolism denotes factors associated with the metabolic syndrome and hyperglycemia, among others. The interplay among hyperglycemia, oxidative stress, and inflammation in the pathogenesis of diabetic kidney disease (DKD) has been broadly explored. Identification of mediators of inflammatory processes involving macrophage infiltration, production of inflammasomes, release of cytokines, and activation of pertinent signaling pathways including mitogen-activated protein kinase, Jun N-terminal kinase, Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway (JAK/STAT), and apoptosis signal-regulating kinase 1 signaling mechanisms have enabled the development of therapeutic agents for DKD. This review describes the evidence supporting the contribution of the inflammatory response and fibrotic changes and focuses on selected, novel, promising drugs as well as repurposed drugs that have made it to phase 2, 3, or 4 of clinical trials in adults with type 2 diabetes mellitus and their potential to become an important part of our armamentarium to improve the management of DKD. Importantly, drugs that solely target inflammatory processes may be insufficient to fully optimize care of patients with DKD because of the complex nature of the disease.

Polyphenol-Rich Extract from Litchi chinensis Seeds Alleviates Hypertension-Induced Renal Damage in Rats

Litchi chinensis seed is a valuable byproduct of the subtropical fruit litchi (L. chinensis Sonn.), whose extract (LSE) has been confirmed to ameliorate dyslipidemia, hyperglycemia, and oxidative stress caused by type 2 diabetes. However, if LSE exerts an effect on anti-hypertension and hypertensive renal damage remains unknown. In this study, 13 polyphenols and one fatty acid were identified by UPLC-Q/TOF-MS. Network pharmacological analysis revealed that the therapeutic effects of LSE may be involved in multitargets and multipathways, such as the TNF signaling pathway, interleukin (IL)-6-mediated signaling pathway, NF-kappa B signaling pathway, removal of superoxide radicals, negative regulation of blood pressure, and so forth. Moreover, spontaneously hypertensive rats (SHRs) were daily gavaged with LSE (60 mg/kg) for 10 weeks. LSE remarkably reduced systolic blood pressure (SBP). The hypertension-induced renal damage was improved by suppressing inflammation and oxidative stress, which was consistent with the prediction of network pharmacology. In addition, LSE treatment remarkably increased the relative abundances of Lactobacillus and the production of short-chain fatty acids in the intestine. Our study indicated that a byproduct of litchi, namely, litchi seed, may be effective in reducing SBP and alleviating hypertensive renal damage.

Apigenin-Loaded Solid Lipid Nanoparticle Attenuates Diabetic Nephropathy Induced by Streptozotocin Nicotinamide Through Nrf2/HO-1/NF-kB Signalling Pathway

Background

Apigenin is known to have a broad-spectrum efficacy in oxidative stress and conditions due to inflammation, although weak absorption, fast metabolic rate and a fast elimination (systemic) limit the pharmacological efficacy of this drug. Hence, we propose the usage of highly bioavailable Apigenin-solid lipid nanoparticles (SLNPs) to recognize such limitations. The defensive function of Apigenin-SLNPs on renal damage induced by streptozotocin (STZ) in animals was studied.

Materials and Methods

We initially injected the rats with 35 mg kg⁻¹ streptozocin intraperitoneally, and after 7 days, the rats were then injected 150 mg kg⁻¹ of metformin intragastrically followed by a once-daily intragastric dose of Apigenin-SLNP (25 or 50 mg kg⁻¹) for a continuous period of 30 days. We then measured the level of insulin and blood glucose, superoxide dismutase, catalase and malondialdehyde in the tissues of the kidney. We also observed messenger-RNA expression of Interleukin-1β, Interleukin-6 and Tumor Necrosis Factor-alpha in renal tissue through RT-PCR technique. Moreover, H&E staining and Western blotting observed the histopathological variations and protein expression of nuclear factor erythroid 2-related factor 2/heme oxygenase/Nuclear Factor-κB signaling pathway, respectively.

Results

An enhancement in the expressing of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 and a suppression in the expression of Nuclear Factor-κB occurred due to Apigenin-SLNPs treatment, which was a result of the protective mechanism of Apigenin-SLNPs which is because of not only its anti-inflammatory function (by inhibition of release of inflammatory factors) but also their anti-oxidant activity (through reduction of lipid peroxidation production).

Conclusion

We found that a protective effect on diabetic nephropathy was shown due to Apigenin-SLNPs, in rats induced with streptozocin maybe through the pathway of nuclear factor erythroid 2-related factor 2/heme oxygenase-1/Nuclear Factor-κB.

Elevated plasma sRAGE and IGFBP7 in heart failure decrease after heart transplantation in association with haemodynamics

AIMS

Metabolic derangement is implicated in the pathophysiology of heart failure (HF) and pulmonary hypertension (PH). We aimed to identify the dynamics of metabolic plasma proteins linked to end-stage HF and associated PH in relation to haemodynamics, before and after heart transplantation (HT).

METHODS AND RESULTS

Twenty-one metabolic plasma proteins were analysed with proximity extension assay in 20 controls and 26 patients before and 1 year after HT. Right heart catheterizations were performed in the HF patients pre-operatively and 1 year after HT. Plasma levels of soluble receptor for advanced glycation end products (sRAGE) and insulin-like growth factor-binding protein 7 (IGFBP7) were higher in HF patients compared with controls (P < 0.0001) and decreased after HT (P < 0.0001), matching controls' levels. The decrease in sRAGE after HT correlated with improved mean pulmonary arterial pressure (rs = 0.7; P < 0.0001), pulmonary arterial wedge pressure (rs = 0.73; P < 0.0001), pulmonary vascular resistance (rs = 0.65; P = 0.00062), and pulmonary arterial compliance (rs = -0.52; P = 0.0074). The change in plasma IGFBP7 after HT correlated with improved mean right atrial pressure (rs = 0.71; P = 0.00011) and N-terminal pro-brain natriuretic peptide (rs = 0.71; P < 0.0001).

CONCLUSIONS

Our results indicate that plasma sRAGE may reflect passive pulmonary vascular congestion and the 'mechanical' state of the pulmonary vasculature in HF patients with or without related PH. Furthermore, sRAGE and IGFBP7 may provide additional insight into the pathophysiological mechanisms in HF and associated PH. Their potential clinical and therapeutic relevance in HF and associated PH need further investigation.

Canagliflozin attenuates isoprenaline-induced cardiac oxidative stress by stimulating multiple antioxidant and anti-inflammatory signaling pathways

The antidiabetic drug canagliflozin is reported to possess several cardioprotective effects. However, no studies have investigated protective effects of canagliflozin in isoprenaline (ISO)-induced cardiac oxidative damage-a model mimicking sympathetic nervous system (SNS) overstimulation-evoked cardiac injuries in humans. Therefore, we investigated protective effects of canagliflozin in ISO-induced cardiac oxidative stress, and their underlying molecular mechanisms in Long-Evans rat heart and in HL-1 cardiomyocyte cell line. Our data showed that ISO administration inflicts pro-oxidative changes in heart by stimulating production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). In contrast, canagliflozin treatment in ISO rats not only preserves endogenous antioxidants but also reduces cardiac oxidative stress markers, fibrosis and apoptosis. Our Western blotting and messenger RNA expression data demonstrated that canagliflozin augments antioxidant and anti-inflammatory signaling involving AMP-activated protein kinase (AMPK), Akt, endothelial nitric oxide synthase (eNOS), nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). In addition, canagliflozin treatment attenuates pro-oxidative, pro-inflammatory and pro-apoptotic signaling mediated by inducible nitric oxide synthase (iNOS), transforming growth factor beta (TGF-β), NADPH oxidase isoform 4 (Nox4), caspase-3 and Bax. Consistently, canagliflozin treatment improves heart function marker in ISO-treated rats. In summary, we demonstrated that canagliflozin produces cardioprotective actions by promoting multiple antioxidant and anti-inflammatory signaling.

Sodium-glucose cotransporters: Functional properties and pharmaceutical potential

Glucose is the most abundant monosaccharide, and an essential source of energy for most living cells. Glucose transport across the cell membrane is mediated by two types of transporters: facilitative glucose transporters (gene name: solute carrier 2A) and sodium-glucose cotransporters (SGLTs; gene name: solute carrier 5A). Each transporter has its own substrate specificity, distribution, and regulatory mechanisms. Recently, SGLT1 and SGLT2 have attracted much attention as therapeutic targets for various diseases. This review addresses the basal and functional properties of glucose transporters and SGLTs, and describes the pharmaceutical potential of SGLT1 and SGLT2.

Revisiting Experimental Models of Diabetic Nephropathy

Diabetes prevalence is constantly increasing and, nowadays, it affects more than 350 million people worldwide. Therefore, the prevalence of diabetic nephropathy (DN) has also increased, becoming the main cause of end-stage renal disease (ESRD) in the developed world. DN is characterized by albuminuria, a decline in glomerular filtration rate (GFR), hypertension, mesangial matrix expansion, glomerular basement membrane thickening, and tubulointerstitial fibrosis. The therapeutic advances in the last years have been able to modify and delay the natural course of diabetic kidney disease (DKD). Nevertheless, there is still an urgent need to characterize the pathways that are involved in DN, identify risk biomarkers and prevent kidney failure in diabetic patients. Rodent models provide valuable information regarding how DN is set and its progression through time. Despite the utility of these models, kidney disease progression depends on the diabetes induction method and susceptibility to diabetes of each experimental strain. The classical DN murine models (Streptozotocin-induced, Akita, or obese type 2 models) do not develop all of the typical DN features. For this reason, many models have been crossed to a susceptible genetic background. Knockout and transgenic strains have also been created to generate more robust models. In this review, we will focus on the description of the new DN rodent models and, additionally, we will provide an overview of the available methods for renal phenotyping.

Antihypertensive and Renal Mechanisms of SGLT2 (Sodium-Glucose Linked Transporter 2) Inhibitors

Empaglifolzin, canagliflozin, and dapagliflozin are SGLT2 (sodium-glucose linked transporter type 2) inhibitors for treatment of type 2 diabetes mellitus that also reduce blood pressure, mortality, and cardiovascular disease and slow the loss of glomerular filtration rate. SGLT2 inhibitors inhibit the coupled reabsorption of sodium and glucose from the proximal tubules, thereby increasing renal glucose and sodium excretion, but they have more widespread renal effects, including inhibition of the sodium:proton exchanger. They increase the delivery of sodium to the loop of Henle and can thereby activate the tubuloglomerular feedback response to correct glomerular hyperfiltration. There are multiple potential mechanisms whereby these drugs lower blood pressure and preserve kidney function that are the focus of this review.

Reduced O-GlcNAcylation and tubular hypoxia contribute to the antifibrotic effect of SGLT2 inhibitor dapagliflozin in the diabetic kidney

Diabetic kidney disease is a worldwide epidemic, and therapies are incomplete. Clinical data suggest that improved renal outcomes by Na⁺-glucose cotransporter 2 inhibitor (SGLT2i) are partly beyond their antihyperglycemic effects; however, the mechanisms are still elusive. Here, we investigated the effect of the SGLT2i dapagliflozin (DAPA) in the prevention of elevated O-GlcNAcylation and tubular hypoxia as contributors of renal fibrosis. Type 1 diabetes was induced by streptozotocin in adult male Wistar rats. After the onset of diabetes, rats were treated for 6 wk with DAPA or DAPA combined with losartan (LOS). The effect of hyperglycemia was tested in HK-2 cells kept under normal or high glucose conditions. To test the effect of hypoxia, cells were kept in 1% O₂ for 2 h. Cells were treated with DAPA or DAPA combined with LOS. DAPA slowed the loss of renal function, mitigated renal tubular injury markers (kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin), and reduced tubulointerstitial fibrosis. DAPA diminished high glucose-induced protein O-GlcNAcylation and moderated the tubular response to hypoxia through the hypoxia-inducible factor pathway. DAPA alone was as effective as combined treatment with LOS in all outcome parameters. These data highlight the role of ameliorated O-GlcNAcylation and diminished tubular hypoxia as important benefits of SGLT2i treatment. Our results support the link between glucose toxicity, tubular hypoxia, and fibrosis, a vicious trio that could be targeted by SGLT2i in kidney diseases of other origins as well.

Effect of SGLT2 inhibitor on renal function in patients with type 2 diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

This study summarizes the evidence from randomized controlled trials (RCTs) to assess the effects of SGLT2 inhibitors on renal function and albuminuria in patients with type 2 diabetes.

MATERIALS/METHODS

We searched PubMed, Web of Science, Cochrane Library and EMBASE for reports published up to March 2018 and included RCTs reporting estimated glomerular filtration rate (eGFR) and/or urine albumin/creatinine ratio (UACR) changes. Data extraction and assessment of research quality based on Cochrane risk biasing tools. Data were calculated to represent the standardized mean difference (SMD) for each study, and the SMDs with 95% confidence intervals (CIs) were pooled using a random effects model.

RESULTS

Fifty-one studies were included that evaluated eGFR levels, and 17 studies were included that evaluated UACR levels. A meta-analysis showed that SGLT2 inhibitors had no significant effect on eGFR levels (SMD - 0.02, 95% CI - 0.06, 0.03, p = 0.45), and eGFR reduction was observed in the subsets of the duration of the trial 12 < duration ≤ 26 weeks (SMD - 0.08, 95% CI - 0.13, - 0.02, p = 0.005) and mean baseline eGFR < 60 ml/min per 1.73 square meters (SMD - 0.22, 95% CI - 0.37, - 0.07, p = 0.004). We found that SGLT2 inhibitors reduced UACR levels in patients with type 2 diabetes (SMD - 0.11, 95% CI - 0.17, - 0.05, p = 0.0001). Compared with monotherapy, the combination with other hypoglycemic agents can reduce albuminuria levels (SMD - 0.13, 95% CI - 0.19, - 0.06, p < 0.0001).

CONCLUSIONS

The effect of SGLT2 inhibitor on eGFR in patients with T2DM was not statistically significant, but it was effective in reducing albuminuria levels.

Narrative review of the effects of antidiabetic drugs on albuminuria

Diabetes mellitus is the most prevalent metabolic disorder worldwide. Glycemic control is the main focus of antidiabetic therapy. However, there are data suggesting that some antidiabetic drugs may have intrinsic beneficial renal effects and protect against the development and progression of albuminuria, thus minimizing the risk of diabetic nephropathy. These pharmacological agents can suppress upstream molecular pathways involved in the pathophysiology of diabetes-induced renal dysfunction such as oxidative stress, inflammatory responses, and apoptosis. In this narrative review, the pathophysiology of albuminuria in patients with diabetic nephropathy is discussed. Furthermore, the renoprotective effects of antidiabetic drugs, focusing on albuminuria, are reviewed.

Effect of canagliflozin, a sodium glucose co-transporter 2 inhibitor, on cisplatin-induced nephrotoxicity in mice

Canagliflozin is a sodium glucose co-transporter 2 (SGLT2) inhibitor that is currently available for the management of type 2 diabetes mellitus. The present study investigated the effect of canagliflozin on cisplatin (CP)-induced nephrotoxicity in mice. The animals were divided into four groups (n = 6). The first and second groups received normal saline (control) and intraperitoneal (i.p.) cisplatin (20 mg/kg) on day 7, respectively. The third and fourth groups were given a single intraperitoneal (i.p.) injection of CP (20 mg/kg) on day 7 and canagliflozin (10 mg/kg/day) and (30 mg/kg/day), for 10 days, respectively. At day 11, animals were anesthetized and blood collected and kidneys were removed. CP significantly increased the plasma urea, creatinine, cystatin C, and clusterin concentrations and neutrophil gelatinase-associated lipocalin (NGAL) activity. In addition, CP increased urinary albumin/creatinine ratio, N-acetyl-β-D-glucosaminidase (NAG) activity, and liver-type fatty acid-binding protein (L-FABP) concentrations and reduced creatinine clearance. CP also significantly increased the plasma concentration of inflammatory cytokines [plasma tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1beta (IL-1β)] and significantly reduced antioxidant indices [catalase, glutathione reductase (GR), and superoxide dismutase (SOD)]. Histopathologically, CP caused a remarkable renal damage compared with control. Canagliflozin significantly ameliorated CP-induced biochemical and histopathological changes. The protective effect of canagliflozin is most likely due to anti-inflammatory and antioxidant effects. Our results show that administration of canagliflozin reversed the biochemical and histopathological indices of CP-induced nephrotoxicity in mice.

Glycemic control by the SGLT2 inhibitor empagliflozin decreases aortic stiffness, renal resistivity index and kidney injury

Background

Arterial stiffness is emerging as an independent risk factor for the development of chronic kidney disease. The sodium glucose co-transporter 2 (SGLT2) inhibitors, which lower serum glucose by inhibiting SGLT2-mediated glucose reabsorption in renal proximal tubules, have shown promise in reducing arterial stiffness and the risk of cardiovascular and kidney disease in individuals with type 2 diabetes mellitus. Since hyperglycemia contributes to arterial stiffness, we hypothesized that the SGLT2 inhibitor empagliflozin (EMPA) would improve endothelial function, reduce aortic stiffness, and attenuate kidney disease by lowering hyperglycemia in type 2 diabetic female mice (db/db).

Materials/methods

Ten-week-old female wild-type control (C57BLKS/J) and db/db (BKS.Cg-Dock7m+/+Leprdb/J) mice were divided into three groups: lean untreated controls (CkC, n = 17), untreated db/db (DbC, n = 19) and EMPA-treated db/db mice (DbE, n = 19). EMPA was mixed with normal mouse chow at a concentration to deliver 10 mg kg⁻¹ day⁻¹, and fed for 5 weeks, initiated at 11 weeks of age.

Results

Compared to CkC, DbC showed increased glucose levels, blood pressure, aortic and endothelial cell stiffness, and impaired endothelium-dependent vasorelaxation. Furthermore, DbC exhibited impaired activation of endothelial nitric oxide synthase, increased renal resistivity and pulsatility indexes, enhanced renal expression of advanced glycation end products, and periarterial and tubulointerstitial fibrosis. EMPA promoted glycosuria and blunted these vascular and renal impairments, without affecting increases in blood pressure. In addition, expression of “reversion inducing cysteine rich protein with Kazal motifs” (RECK), an anti-fibrotic mediator, was significantly suppressed in DbC kidneys and partially restored by EMPA. Confirming the in vivo data, EMPA reversed high glucose-induced RECK suppression in human proximal tubule cells.

Conclusions

Empagliflozin ameliorates kidney injury in type 2 diabetic female mice by promoting glycosuria, and possibly by reducing systemic and renal artery stiffness, and reversing RECK suppression.