Dapagliflozin in focal segmental glomerulosclerosis: a combined human-rodent pilot study

Hepatoprotective and cardioprotective effects of empagliflozin in spontaneously hypertensive rats fed a high-fat diet

A combination of liver and heart dysfunction worsens the prognosis of human survival. The aim of this study was to investigate whether empagliflozin (a sodium-glucose transporter-2 inhibitor) has beneficial effects not only on cardiac and renal function but also on hepatic function. Adult (6-month-old) male spontaneously hypertensive rats (SHR) were fed a high-fat diet (60% fat) for four months to induce hepatic steatosis and mild heart failure. For the last two months, the rats were treated with empagliflozin (empa, 10 mg.kg-1.day-1 in the drinking water). Renal function and oral glucose tolerance test were analyzed in control (n=8), high-fat diet (SHR+HF, n=10), and empagliflozin-treated (SHR+HF+empa, n=9) SHR throughout the study. Metabolic parameters and echocardiography were evaluated at the end of the experiment. High-fat diet feeding increased body weight and visceral adiposity, liver triglyceride and cholesterol concentrations, and worsened glucose tolerance. Although the high-fat diet did not affect renal function, it significantly worsened cardiac function in a subset of SHR rats. Empagliflozin reduced body weight gain but not visceral fat deposition. It also improved glucose sensitivity and several metabolic parameters (plasma insulin, uric acid, and HDL cholesterol). In the liver, empagliflozin reduced ectopic lipid accumulation, lipoperoxidation, inflammation and pro-inflammatory HETEs, while increasing anti-inflammatory EETs. In addition, empagliflozin improved cardiac function (systolic, diastolic and pumping) independent of blood pressure. The results of our study suggest that hepatoprotection plays a decisive role in the beneficial effects of empagliflozin in preventing the progression of cardiac dysfunction induced by high-fat diet feeding.

Nascent shifts in renal cellular metabolism, structure, and function due to chronic empagliflozin in prediabetic mice

Sodium-glucose cotransporter, type 2 inhibitors (SGLT2i) are emerging as the gold standard for treatment of type 2 diabetes (T2D) with renal protective benefits independent of glucose lowering. We took a high-level approach to evaluate the effects of the SGLT2i, empagliflozin (EMPA) on renal metabolism and function in a prediabetic model of metabolic syndrome. Male and female 12-wk-old TallyHo (TH) mice, and their closest genetic lean strain (Swiss-Webster, SW) were treated with a high-milk-fat diet (HMFD) plus/minus EMPA (@0.01%) for 12-wk. Kidney weights and glomerular filtration rate were slightly increased by EMPA in the TH mice. Glomerular feature analysis by unsupervised clustering revealed sexually dimorphic clustering, and one unique cluster relating to EMPA. Periodic acid Schiff (PAS) positive areas, reflecting basement membranes and mesangium were slightly reduced by EMPA. Phasor-fluorescent life-time imaging (FLIM) of free-to-protein bound NADH in cortex showed a marginally greater reliance on oxidative phosphorylation with EMPA. Overall, net urine sodium, glucose, and albumin were slightly increased by EMPA. In TH, EMPA reduced the sodium phosphate cotransporter, type 2 (NaPi-2), but increased sodium hydrogen exchanger, type 3 (NHE3). These changes were absent or blunted in SW. EMPA led to changes in urine exosomal microRNA profile including, in females, enhanced levels of miRs 27a-3p, 190a-5p, and 196b-5p. Network analysis revealed "cancer pathways" and "FOXO signaling" as the major regulated pathways. Overall, EMPA treatment to prediabetic mice with limited renal disease resulted in modifications in renal metabolism, structure, and transport, which may preclude and underlie protection against kidney disease with developing T2D.NEW & NOTEWORTHY Renal protection afforded by sodium glucose transporter, type 2 inhibitors (SGLT2i), e.g., empagliflozin (EMPA) involves complex intertwined mechanisms. Using a novel mouse model of obesity with insulin resistance, the TallyHo/Jng (TH) mouse on a high-milk-fat diet (HMFD), we found subtle changes in metabolism including altered regulation of sodium transporters that line the renal tubule. New potential epigenetic determinants of metabolic changes relating to FOXO and cancer signaling pathways were elucidated from an altered urine exosomal microRNA signature.

Fibrosis in Chronic Kidney Disease: Pathophysiology and Therapeutic Targets

Chronic kidney disease (CKD) is a slowly progressive condition characterized by decreased kidney function, tubular injury, oxidative stress, and inflammation. CKD is a leading global health burden that is asymptomatic in early stages but can ultimately cause kidney failure. Its etiology is complex and involves dysregulated signaling pathways that lead to fibrosis. Transforming growth factor (TGF)-β is a central mediator in promoting transdifferentiation of polarized renal tubular epithelial cells into mesenchymal cells, resulting in irreversible kidney injury. While current therapies are limited, the search for more effective diagnostic and treatment modalities is intensive. Although biopsy with histology is the most accurate method of diagnosis and staging, imaging techniques such as diffusion-weighted magnetic resonance imaging and shear wave elastography ultrasound are less invasive ways to stage fibrosis. Current therapies such as renin-angiotensin blockers, mineralocorticoid receptor antagonists, and sodium/glucose cotransporter 2 inhibitors aim to delay progression. Newer antifibrotic agents that suppress the downstream inflammatory mediators involved in the fibrotic process are in clinical trials, and potential therapeutic targets that interfere with TGF-β signaling are being explored. Small interfering RNAs and stem cell-based therapeutics are also being evaluated. Further research and clinical studies are necessary in order to avoid dialysis and kidney transplantation.

Cardiovascular Risk in Patients With Glomerular Disease: A Narrative Review of the Epidemiology, Mechanisms, Management, and Patient Priorities

Purpose of review

Cardiovascular (CV) disease is a major cause of morbidity and mortality for patients with glomerular disease. Despite the fact that mechanisms underpinning CV disease risk in this population are likely distinct from other forms of kidney disease, treatment and preventive strategies tend to be extrapolated from studies of patients with undifferentiated chronic kidney disease (CKD). There is an unmet need to delineate the pathophysiology of CV disease in patients with glomerular disease, establish unique risk factors, and identify novel therapeutic targets for disease prevention. The aims of this narrative review are to summarize the existing knowledge regarding the epidemiology, molecular mechanisms, and management of CV disease in patients with common glomerular disease, highlight the patient perspective, and propose specific areas for future study.

Sources of information

The literature for this narrative review was accessed using common research search engines, including PubMed, PubMed Central, Medline, and Google Scholar. Information for the patient perspective section was collected through iterative discussions with a patient partner.

Methods

We reviewed the epidemiology, molecular mechanisms of disease, management approaches, and the patient perspective in relation to CV disease in patients with glomerulopathies. Throughout, we have highlighted the current knowledge and have discussed future research approaches, both clinical and translational, while integrating the patient perspective.

Key findings

Patients with glomerular disease have significant CV disease risk driven by multifactorial, molecular mechanisms originating from their glomerular disease but complicated by existing comorbidities, kidney disease, and medication side effects. The current approach to risk stratification and treatment relies heavily on existing data from CKD patients, but this may not always be appropriate given the unique pathophysiology and mechanisms associated with CV disease risk in patients with glomerular disease. We highlight the need for ongoing glomerular disease-focused studies aimed to better delineate CV disease risk, while integrating the patient perspective.

Limitations

This is a narrative review and does not represent a comprehensive and systematic review of the literature.

Sodium-Glucose Co-Transporter 2 Inhibitors: Mechanism of Action and Efficacy in Non-Diabetic Kidney Disease from Bench to Bed-Side

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are currently available for the management of type 2 diabetes mellitus. SGLT2i acts by inhibiting renal SGLT2, thereby increasing glucosuria and lowering serum glucose. Recent trials are emerging supporting a role for SGLT2i irrespective of the diabetic status pointing towards that SGLT2i have other mechanisms of actions beyond blood sugar control. In this review, we will shed light on the role of this group of medications that act as SGLT2i in non-diabetics focusing on pre-clinical and clinical data highlighting the mechanism of renoprotection and effects of SGLT2i in the non-diabetic kidneys.

Narrative review investigating the nephroprotective mechanisms of sodium glucose cotransporter type 2 inhibitors in diabetic and nondiabetic patients with chronic kidney disease

Background and aims

Outcome trials using sodium glucose cotransporter type 2 inhibitors have consistently shown their potential to preserve kidney function in diabetic and nondiabetic patients. Several mechanisms have been introduced which may explain the nephroprotective effect of sodium glucose cotransporter type 2 inhibitors beyond lowering blood glucose. This current narrative review has the objective to describe main underlying mechanisms causing a nephroprotective effect and to show similarities as well as differences between proposed mechanisms which can be observed in patients with diabetic and nondiabetic chronic kidney disease.

Methods

We performed a narrative review of the literature on Pubmed and Embase. The research string comprised various combinations of items including "chronic kidney disease", "sodium glucose cotransporter 2 inhibitor" and "mechanisms". We searched for original research and review articles published until march, 2022. The databases were searched independently and the agreements by two authors were jointly obtained.

Results

Sodium glucose cotransporter type 2 inhibitors show systemic, hemodynamic, and metabolic effects. Systemic effects include reduction of blood pressure without compensatory activation of the sympathetic nervous system. Hemodynamic effects include restoration of tubuloglomerular feedback which may improve pathologic hyperfiltration observed in most cases with chronic kidney disease. Current literature indicates that SGLT2i may not improve cortical oxygenation and may reduce medullar oxygenation.

Conclusion

Sodium glucose cotransporter type 2 inhibitors cause nephroprotective effects by several mechanisms. However, several mediators which are involved in the underlying pathophysiology may be different between diabetic and nondiabetic patients.

Reno- and cardioprotective molecular mechanisms of SGLT2 inhibitors beyond glycemic control: from bedside to bench

Large placebo-controlled clinical trials have shown that sodium-glucose cotransporter-2 inhibitors (SGLT2i) delay the deterioration of renal function and reduce cardiovascular events in a glucose-independent manner, thereby ultimately reducing mortality in patients with chronic kidney disease (CKD) and/or heart failure. These existing clinical data stimulated preclinical studies aiming to understand the observed clinical effects. In animal models, it was shown that the beneficial effect of SGLT2i on the tubuloglomerular feedback (TGF) improves glomerular pressure and reduces tubular workload by improving renal hemodynamics, which appears to be dependent on salt intake. High salt intake might blunt the SGLT2i effects on the TGF. Beyond the salt-dependent effects of SGLT2i on renal hemodynamics, SGLT2i inhibited several key aspects of macrophage-mediated renal inflammation and fibrosis, including inhibiting the differentiation of monocytes to macrophages, promoting the polarization of macrophages from a proinflammatory M1 phenotype to an anti-inflammatory M2 phenotype, and suppressing the activation of inflammasomes and major proinflammatory factors. As macrophages are also important cells mediating atherosclerosis and myocardial remodeling after injury, the inhibitory effects of SGLT2i on macrophage differentiation and inflammatory responses may also play a role in stabilizing atherosclerotic plaques and ameliorating myocardial inflammation and fibrosis. Recent studies suggest that SGLT2i may also act directly on the Na+/H+ exchanger and Late-INa in cardiomyocytes thus reducing Na+ and Ca2+ overload-mediated myocardial damage. In addition, the renal-cardioprotective mechanisms of SGLT2i include systemic effects on the sympathetic nervous system, blood volume, salt excretion, and energy metabolism.

Intrarenal Mechanisms of Sodium-Glucose Cotransporter-2 Inhibitors on Tubuloglomerular Feedback and Natriuresis

When sodium-glucose cotransporter-2 (SGLT2) inhibitors were first introduced a decade ago, no one expected them to have substantial effects beyond their known glucose-lowering effects, until the emergence of evidence of their robust renal and cardiovascular benefits showing that they could attenuate progression of kidney disease, irrespective of diabetes, as well as prevent the development of acute kidney injury. Still, the precise and elaborate mechanisms underlying the major organ protection of SGLT2 inhibitors remain unclear. SGLT2 inhibitors inhibit the reabsorption of sodium and glucose in the proximal tubule of the kidney and then recovers tubuloglomerular feedback, whereby SGLT2 inhibitors reduce glomerular hyperfiltration. This simple demonstration of their beneficial effects has perplexed experts in seeking more plausible and as yet undisclosed explanations for the whole effects of SGLT2 inhibitors, including metabolism reprogramming and the modulation of hypoxia, inflammation, and oxidative stress. Given that the renal benefits of SGLT2 inhibitors in patients with kidney disease but without diabetes were comparable to those seen in patients with diabetes, it may be reasonable to keep the emphasis on their hemodynamic actions. In this context, the aim of the present review is to provide a comprehensive overview of renal hemodynamics in individuals with diabetes who are treated with SGLT2 inhibitors, with a focus on natriuresis associated with the regulation of tubuloglomerular feedback and potential aquaresis. Throughout the discussion of alterations in renal sodium and water transports, particular attention will be given to the potential enhancement of adenosine and its receptors following SGLT2 inhibition.

Synergism of calycosin and bone marrow-derived mesenchymal stem cells to combat podocyte apoptosis to alleviate adriamycin-induced focal segmental glomerulosclerosis

BACKGROUND

Bone marrow-derived mesenchymal stem cells (MSCs) show podocyte-protective effects in chronic kidney disease. Calycosin (CA), a phytoestrogen, is isolated from Astragalus membranaceus with a kidney-tonifying effect. CA preconditioning enhances the protective effect of MSCs against renal fibrosis in mice with unilateral ureteral occlusion. However, the protective effect and underlying mechanism of CA-pretreated MSCs (MSCs^CA) on podocytes in adriamycin (ADR)-induced focal segmental glomerulosclerosis (FSGS) mice remain unclear.

AIM

To investigate whether CA enhances the role of MSCs in protecting against podocyte injury induced by ADR and the possible mechanism involved.

METHODS

ADR was used to induce FSGS in mice, and MSCs, CA, or MSCs^CA were administered to mice. Their protective effect and possible mechanism of action on podocytes were observed by Western blot, immunohistochemistry, immunofluorescence, and real-time polymerase chain reaction. In vitro, ADR was used to stimulate mouse podocytes (MPC5) to induce injury, and the supernatants from MSC-, CA-, or MSCs^CA-treated cells were collected to observe their protective effects on podocytes. Subsequently, the apoptosis of podocytes was detected in vivo and in vitro by Western blot, TUNEL assay, and immunofluorescence. Overexpression of Smad3, which is involved in apoptosis, was then induced to evaluate whether the MSCs^CA-mediated podocyte protective effect is associated with Smad3 inhibition in MPC5 cells.

RESULTS

CA-pretreated MSCs enhanced the protective effect of MSCs against podocyte injury and the ability to inhibit podocyte apoptosis in ADR-induced FSGS mice and MPC5 cells. Expression of p-Smad3 was upregulated in mice with ADR-induced FSGS and MPC5 cells, which was reversed by MSC^CA treatment more significantly than by MSCs or CA alone. When Smad3 was overexpressed in MPC5 cells, MSCs^CA could not fulfill their potential to inhibit podocyte apoptosis.

CONCLUSION

MSCs^CA enhance the protection of MSCs against ADR-induced podocyte apoptosis. The underlying mechanism may be related to MSCs^CA-targeted inhibition of p-Smad3 in podocytes.

SGLT2 Inhibitors: The Sweet Success for Kidneys

Sodium-glucose cotransporter-2 inhibitors (SGLT2 inhibitors) were originally developed as antidiabetic agents, with cardiovascular (CV) outcome trials demonstrating improved CV outcomes in patients with type 2 diabetes mellitus (T2D). Secondary analyses of CV outcome trials and later dedicated kidney outcome trials consistently reported improved kidney-related outcomes independent of T2D status and across a range of kidney function and albuminuria. Importantly, SGLT2 inhibitors are generally safe and well tolerated, with clinical trials and real-world analyses demonstrating a decrease in the risk of acute kidney injury. The kidney protective effects of SGLT2 inhibitors generally extend across different members of the class, possibly on the basis of hemodynamic, metabolic, anti-inflammatory, and antifibrotic mechanisms. In this review, we summarize the effects of SGLT2 inhibitors on kidney outcomes in diverse patient populations.

Empagliflozin increases kidney weight due to increased cell size in the proximal tubule S3 segment and the collecting duct

The inhibition of renal SGLT2 glucose reabsorption has proven its therapeutic efficacy in chronic kidney disease. SGLT2 inhibitors (SGLTi) have been intensively studied in rodent models to identify the mechanisms of SGLT2i-mediated nephroprotection. So far, the overwhelming effects from clinical trials, could only partially be reproduced in rodent models of renal injury. However, a commonly disregarded observation from these studies, is the increase in kidney weight after SGLT2i administration. Increased kidney mass often relies on tubular growth in response to reabsorption overload during glomerular hyperfiltration. Since SGLT2i suppress hyperfiltration but concomitantly increase renal weight, it seems likely that SGLT2i have a growth promoting effect on the kidney itself, independent of GFR control. This study aimed to investigate the effect of SGLT2i on kidney growth in wildtype animals, to identify enlarged nephron segments and classify the size increase as hypertrophic/hyperplastic growth or cell swelling. SGLT2i empagliflozin increased kidney weight in wildtype mice by 13% compared to controls, while bodyweight and other organs were not affected. The enlarged nephron segments were identified as SGLT2-negative distal segments of proximal tubules and as collecting ducts by histological quantification of tubular cell area. In both segments protein/DNA ratio, a marker for hypertrophic growth, was increased by 6% and 12% respectively, while tubular nuclei number (hyperplasia) was unchanged by empagliflozin. SGLT2-inhibition in early proximal tubules induces a shift of NaCl resorption along the nephron causing compensatory NaCl and H₂O reabsorption and presumably cell growth in downstream segments. Consistently, in collecting ducts of empagliflozin-treated mice, mRNA expression of the Na⁺-channel ENaC and the H₂O-channels Aqp-2/Aqp-3 were increased. In addition, the hypoxia marker Hif1α was found increased in intercalated cells of the collecting duct together with evidence for increased proton secretion, as indicated by upregulation of carbonic anhydrases and acidified urine pH in empagliflozin-treated animals. In summary, these data show that SGLT2i induce cell enlargement by hypertrophic growth and possibly cell swelling in healthy kidneys, probably as a result of compensatory glucose, NaCl and H₂O hyperreabsorption of SGLT2-negative segments. Particularly affected are the SGLT2-negative proximal tubules (S3) and the collecting duct, areas of low O₂ availability.

Novel insights in classic versus relative glomerular hyperfiltration and implications on pharmacotherapy

PURPOSE OF REVIEW

Glomerular filtration rate (GFR) assessment and its estimation (eGFR) is a long-lasting challenge in medicine and public health. Current eGFR formulae are indexed for standardized body surface area (BSA) of 1.73 m2, ignoring persons and populations wherein the ratio of BSA or metabolic rate to nephron number might be different, due to increased BSA, increased metabolic rate or reduced nephron number. These equations are based on creatinine, cystatin C or a combination of the two, which adds another confounder to eGFR assessment. Unusually high GFR values, also known as renal hyperfiltration, have not been well defined under these equations.

RECENT FINDINGS

Special conditions such as solitary kidney in kidney donors, high dietary protein intake, obesity and diabetes are often associated with renal hyperfiltration and amenable to errors in GFR estimation. In all hyperfiltration types, there is an increased intraglomerular pressure that can be physiologic, but its persistence over time is detrimental to glomerulus leading to progressive glomerular damage and renal fibrosis. Hyperfiltration might be underdiagnosed due to BSA standardization embedded in the formula. Hence, timely intervention is delayed. Reducing intraglomerular pressure in diabetes can be achieved by SGLT2 inhibitors or low protein diet to reverse the glomerulopathy process.

SUMMARY

Accurate identification of glomerular hyperfiltration as a pre-CKD condition needs accurate estimation of GFR in the above normal range should establish a threshold for timely intervention.

Expectations in children with glomerular diseases from SGLT2 inhibitors

Chronic kidney disease (CKD) is a global public healthcare concern in the pediatric population, where glomerulopathies represent the second most common cause. Although classification and diagnosis of glomerulopathies still rely mostly on histopathological patterns, patient stratification should complement information supplied by kidney biopsy with clinical data and etiological criteria. Genetic determinants of glomerular injury are particularly relevant in children, with important implications for prognosis and treatment. Targeted therapies addressing the primary cause of the disease are available for a limited number of glomerular diseases. Consequently, in the majority of cases, the treatment of glomerulopathies is actually the treatment of CKD. The efficacy of the currently available strategies is limited, but new prospects evolve. Although the exact mechanisms of action are still under investigation, accumulating data in adults demonstrate the efficacy of sodium-glucose transporter 2 inhibitors (SGLT2i) in slowing the progression of CKD due to diabetic and non-diabetic kidney disease. SGLT2i has proved effective on other comorbidities, such as obesity, glycemic control, and cardiovascular risk that frequently accompany CKD. The use of SGLT2i is not yet approved in children. However, no pathophysiological clues theoretically exclude their application. The hallmark of pediatric CKD is the inevitable imbalance between the metabolic needs of a growing child and the functional capacity of a failing kidney to handle those needs. In this view, developing better strategies to address any modifiable progressor in kidney disease is mandatory, especially considering the long lifespan typical of the pediatric population. By improving the hemodynamic adaptation of the kidney and providing additional beneficial effects on the overall complications of CKD, SGLT2i is a candidate as a potentially innovative drug for the treatment of CKD and glomerular diseases in children.

À qui un néphrologue doit-il prescrire un iSGLT2 ? Indications of SGLT2 inhibitors in kidney disease: who, why and when?

Inhibitors of sodium glucose co-transporter type 2 (iSGLT2) constitute a considerable advance in the management of patients with diabetes, heart failure and with chronic kidney disease (CKD). Randomized controlled studies have shown a significant reduction of cardiovascular risk in diabetic type 2 and/or heart failure with reduced ejection fraction patients. These studies observed a risk reduction of worsening nephropathy, leading to randomized controlled studies in CKD patients : CREDENCE, DAPA-CKD and EMPA-KIDNEY. iSGLT2 are associated with a slower progression toward end-stage kidney disease, a lower slope of GFR and a lower rate of albuminuria. In CKD patients with proteinuria either diabetic or not, the DAPA-CKD and the EMPA-KIDNEY studies have demonstrated a nephroprotective effect. This effect has not been found for patients without proteinuria. For the other nephropathies, further studies are required to confirm results obtained in patients without type 2 diabetes and macroalbuminuria. Therefore, the indication of iSGLT2, with appropriate dose of RAS inhibitor, seems undeniable to an optimal nephroprotection in CKD patients with type 2 diabetes and/or albuminuria and/or heart failure. They must be prescribed in addition to conventional nephroprotective and cardioprotective treatments and care. Side effects are limited. However, special education and monitoring concerning risks of genital infection and euglycemic ketoacidosis (diabetic patients) must be taken in mind. The therapeutic arsenal for CKD patients is expanding, leading to consider a personalized care according to the underlying nephropathy. © 2022 Published by Elsevier Masson SAS on behalf of Société francophone de néphrologie, dialyse et transplantation.

Empagliflozin Is Not Renoprotective in Non-Diabetic Rat Models of Chronic Kidney Disease

Gliflozins (sodium-glucose transporter-2 inhibitors) exhibited renoprotective effects not only in diabetic but also in non-diabetic patients with chronic kidney disease (CKD). Controversial results were reported in experimental non-diabetic models of CKD. Therefore, we examined empagliflozin effects in three CKD models, namely, in fawn-hooded hypertensive (FHH) rats, uninephrectomized salt-loaded (UNX + HS) rats, and in rats with Goldblatt hypertension (two-kidney, one-clip 2K1C) that were either untreated or treated with empagliflozin (10 mg/kg/day) for eight weeks. Plethysmography blood pressure (BP) was recorded weekly, and renal parameters (proteinuria, plasma urea, creatinine clearance, and sodium excretion) were analyzed three times during the experiment. At the end of the study, blood pressure was also measured directly. Markers of oxidative stress (TBARS) and inflammation (MCP-1) were analyzed in kidney and plasma, respectively. Body weight and visceral adiposity were reduced by empagliflozin in FHH rats, without a significant effect on BP. Experimentally induced CKD (UNX + HS and 2K1C) was associated with a substantial increase in BP and relative heart and kidney weights. Empagliflozin influenced neither visceral adiposity nor BP in these two models. Although empagliflozin increased sodium excretion, suggesting effective SGLT-2 inhibition, it did not affect diuresis in any experimental model. Unexpectedly, empagliflozin did not provide renoprotection because proteinuria, plasma urea, and plasma creatinine were not lowered by empagliflozin treatment in all three CKD models. In line with these results, empagliflozin treatment did not decrease TBARS or MCP-1 levels in either model. In conclusion, empagliflozin did not provide the expected beneficial effects on kidney function in experimental models of CKD.

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.

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.

The Effects of Sodium-Glucose Cotransporter-2 Inhibitors (SLGT-2i) on Cardiovascular and Renal Outcomes in Non-diabetic Patients: A Systematic Review

Globally, cardiovascular disease (CVD) and chronic kidney disease (CKD) are the leading causes of mortality. Despite medical advances, these illnesses are still underdiagnosed and undermanaged. Sodium-glucose cotransporter-2 inhibitors (SGLT-2i) have recently emerged as a potential class of medications with promising cardiovascular and renal safety in non-diabetic patients. In this systematic review, we explored the outcomes of cardiovascular and renal protective effects utilizing SGLT-2i in three large randomized clinical trials with a cohort of both diabetes and non-diabetes patients. In these studies, data conferred that there is a significant reduction in heart failure (HF) hospitalization, as well as cardiovascular and all-cause mortality. Moreover, SGLT-2i impede the progression to and death from CKD. Additionally, we reviewed trials solely done on non-diabetics which demonstrated benefits in patients with established HF with reduced ejection fraction, though the fact that these studies had a smaller sample size. We also discussed some of the potential mechanisms of action of SGLT-2i on cardiovascular and renal outcomes that are beyond anti-hyperglycemic control. There is ongoing research involving a larger number of non-diabetes patients that may provide more information about the efficacy of these drugs besides anti-diabetic medications in the future. Finally, this is the first systematic review that has provided a perspective on the currently available trials, which offer evidence supporting the potential benefits of SGLT-2i on cardiovascular and renal outcomes in non-diabetic individuals.

Characteristics and molecular mechanisms through which SGLT2 inhibitors improve metabolic diseases: A mechanism review

Metabolic diseases, such as diabetes, gout and hyperlipidemia are global health challenges. Among them, diabetes has been extensively investigated. Type 2 diabetes mellitus (T2DM), which is characterized by hyperglycemia, is a complex metabolic disease that is associated with various metabolic disorders. The newly developed oral hypoglycemic agent, sodium-glucose cotransporter 2 (SGLT2) inhibitor, has been associated with glucose-lowering effects and it affects metabolism in various ways. However, the potential mechanisms of SGLT2 inhibitors in metabolic diseases have not fully reviewed. Many of the effects beyond glycemic control must be considered off-target effects. Therefore, we reviewed the effects of SGLT2 inhibition on metabolic diseases such as obesity, hypertension, hyperlipidemia, hyperuricemia, fatty liver disease, insulin resistance, osteoporosis and fractures. Moreover, we elucidated their molecular mechanisms to provide a theoretical basis for metabolic disease treatment.

“Greedy Organs Hypothesis” for sugar and salt in the pathophysiology of non-communicable diseases in relation to sodium-glucose co-transporters in the intestines and the kidney

Deposition of visceral fat and insulin resistance play central role in the development of non-communicable diseases (NCDs) including obesity, hypertension and type 2 diabetes. However, we shed more light upon the intestines and the kidney as a strong driver of NCDs. Based upon unexpected outcomes of clinical trials using sodium-glucose cotransporter (SGLT) 2 inhibitors to demonstrate their actions for not only body weight reduction and blood glucose fall but also remarkable cardiorenal protection, we speculate that hyperfunction of the intestines and the kidney is one of critical contributing factors for initiation of NCDs. By detecting high amount of glucose and sodium chloride around them by sweet/salt taste sensors, the intestines and the kidney are designed to (re)absorb these nutrients by up-regulating SGLT1 or SGLT2. We designate these hyperfunctioning organs for nutrient uptake as “greedy organs”. The greedy organs can induce NCDs (“greedy organ hypothesis”). SGLTs are regulated by glucose and sodium chloride, and SGLTs or other genes can be “greedy genes.” Regulating factors for greedy organs are renin-angiotensin system, renal sympathetic nervous activity, gut inflammation/microbiota or oxidative stress. Mitigation of organ greediness by SGLT2 inhibitors, ketone bodies, bariatric surgery, and regular lifestyle to keep rhythmicity of biological clock are promising.

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We propose the concept of “Greedy Organs” hypothesis as a possible cause of NCDs.

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Clinical implication of greedy kidney is supported by the effect of SGLT2 inhibitors.

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The significance of greedy intestines is suggested by the effect of bariatric surgery.

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The intestines and kidney become hyperactive through upregulation of SGLT1 or 2.

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To mitigate “greedy organs” should be a promising strategy against NCDs.

Extending the ambit of SGLT2 inhibitors beyond diabetes: a review of clinical and preclinical studies on non-diabetic kidney disease

BACKGROUND

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) are novel antidiabetic agents with overwhelming cardiorenal protection. Recent trials focusing on the nephroprotective role of SGLT2i have underscored its success as a phenomenal agent in halting the progression of kidney disease in patients with and without Type 2 diabetes mellitus. Multitudes of pleiotropic effects on tubules have raised hopes for reasonable nephroprotection beyond the purview of the hyperglycemic milieu.

AREA COVERED

This review summarizes various animal and human data as evidence for the utility of SGLT2i in non-diabetic chronic kidney disease (CKD). Web-based medical database entries were searched. On the premise of existing evidence, we have discussed mechanisms likely contributing to nephroprotection by SGLT2i in patients with non-diabetic CKD.

EXPERT OPINION

Further elucidation of mechanisms of nephroprotection offered by SGLT2i is required to extend its use as a nephroprotective agent. The use of non-traditional markers of kidney damage in future studies would improve the evaluation of their role in attenuating CKD progression. Emerging animal data support the early use of SGLT2i in states of modest proteinuria for superior outcomes. Future long-term trials in patients should aim to address the time of intervention with SGLT2i during the natural disease course of CKD for best outcomes.

Empagliflozin Reduces Renal Hyperfiltration in Response to Uninephrectomy, but Is Not Nephroprotective in UNx/DOCA/Salt Mouse Models

Large-scale clinical outcome studies demonstrated the efficacy of SGLT2 inhibitors in patients with type II diabetes. Besides their therapeutic efficacy in diabetes, significant renoprotection was observed in non-diabetic patients with chronic kidney disease (CKD), suggesting the existence of glucose-independent beneficial effects of SGLT2 inhibitors. However, the relevant mechanisms by which SGLT2 inhibition delays the progression of renal injury are still largely unknown and speculative. Previous studies showed that SGLT2 inhibitors reduce diabetic hyperfiltration, which is likely a key element in renoprotection. In line with this hypothesis, this study aimed to investigate the nephroprotective effects of the SGLT2 inhibitor empagliflozin (EMPA) in different mouse models with non-diabetic hyperfiltration and progressing CKD to identify the underlying diabetes-independent cellular mechanisms. Non-diabetic hyperfiltration was induced by unilateral nephrectomy (UNx). Since UNx alone does not result in renal damage, renal disease models with varying degrees of glomerular damage and albuminuria were generated by combining UNx with high NaCl diets ± deoxycorticosterone acetate (DOCA) in different mouse strains with and without genetic predisposition for glomerular injury. Renal parameters (GFR, albuminuria, urine volume) were monitored for 4–6 weeks. Application of EMPA via the drinking water resulted in sufficient EMPA plasma concentration and caused glucosuria, diuresis and in some models renal hypertrophy. EMPA had no effect on GFR in untreated wildtype animals, but significantly reduced hyperfiltration after UNx by 36%. In contrast, EMPA did not reduce UNx induced hyperfiltration in any of our kidney disease models, regardless of their degree of glomerular damage caused by DOCA/salt treatment. Consistent with the lack of reduction in glomerular hyperfiltration, EMPA-treated animals developed albuminuria and renal fibrosis to a similar extent as H₂O control animals. Taken together, the data clearly indicate that blockade of SGLT2 has the potential to reduce non-diabetic hyperfiltration in otherwise untreated mice. However, no effects on hyperfiltration or progression of renal injury were observed in hypervolemic kidney disease models, suggesting that high salt intake and extracellular volume might attenuate the protective effects of SGLT2 blockers.

Different Effects of Empagliflozin on Markers of Mineral-Bone Metabolism in Diabetic and Non-Diabetic Patients with Stage 3 Chronic Kidney Disease

Background and objectives: Treatment with sodium-glucose co-transporter 2 (SGLT2) inhibitors decrease tubular reabsorption of phosphate, which may explain the reduction of bone mineral density and an excess of bone fractures observed in some studies with this class of drugs. Since an increased risk of bone fractures may also be a result of diabetes itself, our study aimed to compare the effect of empagliflozin on the markers of mineral-bone metabolism between diabetic (DKD) and non-diabetic (ND-CKD) patients with stage 3 chronic kidney disease (CKD). Materials and Methods: Forty-two patients with stage 3 CKD and A2 albuminuria, including 18 with DKD and 24 ND-CKD, were investigated. All subjects received 10 mg empagliflozin for 7 days. Serum calcium, phosphate, parathormone (PTH), calcitriol, bone alkaline phosphatase (BAP), FGF-23 and urine calcium, phosphate, albumin and the renal tubular maximum reabsorption rate of phosphate to the glomerular filtration rate (TmP-GFR) were measured before and after empagliflozin administration. Differences in biomarkers response to empagliflozin between DKD and ND-CKD were the main measures of outcome. Results: There was a significant increase of PTH, FGF-23 and phosphate in DKD but not in ND-CKD whereas BAP and TmP/GFR did not change in either group. The reduction of albuminuria was only significant in ND-CKD. Conclusions: The effect of SGLT2 inhibitor on serum mineral and bone markers and on albuminuria in patients with CKD may be differently modified by the presence of diabetes mellitus.

Antihypertensive and metabolic effects of empagliflozin in Ren-2 transgenic rats, an experimental non-diabetic model of hypertension

The new antidiabetic drugs, gliflozins, inhibit sodium-glucose transporter-2 in renal proximal tubules promoting glucose and sodium excretion. This leads not only to a significant improvement of glucose control but also to the reduction of blood pressure and body weight in both diabetic patients and experimental models. We examined whether these beneficial effects can also be achieved in a non-diabetic hypertensive model, namely in Ren-2 transgenic rats (TGR). Adult 6-month-old hypertensive TGR and their normotensive controls (Hannover Sprague-Dawley rats), were either untreated or treated with empagliflozin (10 mg/kg/day) for two months. Telemetric blood pressure monitoring, renal parameters as well as cardiac function via echocardiography were analyzed during the experiment. At the end of the study, the contribution of major vasoactive systems to blood pressure maintenance was studied. Metabolic parameters and markers of oxidative stress and inflammation were also analyzed. Empagliflozin had no effect on plasma glucose level but partially reduced blood pressure in TGR. Although food consumption was substantially higher in empagliflozin-treated TGR compared to the untreated animals, their body weight and the amount of epididymal and perirenal fat was decreased. Empagliflozin had no effect on proteinuria, but it decreased plasma urea, attenuated renal oxidative stress and temporarily increased urinary urea excretion. Several metabolic (hepatic triglycerides, non-esterified fatty acids, insulin) and inflammatory (TNF-α, leptin) parameters were also improved by empagliflozin treatment. By contrast, echocardiography did not reveal any effect of empagliflozin on cardiac function. In conclusion, empagliflozin exerted beneficial antihypertensive, anti-inflammatory and metabolic effects also in a non-diabetic hypertensive model.

Effect of dapagliflozin on urinary albumin excretion in patients with chronic kidney disease with and without type 2 diabetes: a prespecified analysis from the DAPA-CKD trial

BACKGROUND

Reductions in albuminuria are associated with a subsequent lower risk of kidney failure in patients with chronic kidney disease. The SGLT2 inhibitor dapagliflozin significantly reduced albuminuria in patients with type 2 diabetes and normal or near-normal kidney function. Whether this effect persists in patients with chronic kidney disease with and without type 2 diabetes is unknown. We assessed the effects of dapagliflozin on albuminuria in patients with chronic kidney disease with and without type 2 diabetes in the dapagliflozin and prevention of adverse outcomes in chronic kidney disease (DAPA-CKD) trial.

METHODS

DAPA-CKD was a multicentre, double-blind, placebo-controlled, randomised trial done at 386 sites in 21 countries. Patients were eligible for the trial if they had chronic kidney disease, defined as an estimated glomerular filtration rate (eGFR) between 25 mL/min per 1·73 m² and 75 mL/min per 1·73 m² and a urinary albumin-to-creatinine ratio (UACR) between 200 mg/g and 5000 mg/g (22·6 to 565·6 mg/mmol). Participants were randomly assigned to dapagliflozin 10 mg (AstraZeneca; Gothenburg, Sweden) once daily or matching placebo, in accordance with the sequestered, fixed randomisation schedule, using balanced blocks to ensure an approximate 1:1 ratio. Change in albuminuria was a pre-specified exploratory outcome of DAPA-CKD. Regression in UACR stage, defined as a transition from macroalbuminuria (≥300 mg/g) to microalbuminuria or normoalbuminuria (<300 mg/g), and progression in UACR stage, defined as a transition from less than 3000 mg/g to 3000 mg/g or greater, were additional discrete endpoints. The trial is registered with ClinicalTrials.gov, NCT03036150.

FINDINGS

Between Feb 2, 2017, and April 3, 2020, 4304 patients were recruited and randomly assigned to either dapagliflozin (n=2152) or placebo (n=2152). Median UACR was 949 mg/g (IQR 477 to 1885). Overall, compared with placebo, dapagliflozin reduced geometric mean UACR by 29·3% (95% CI -33·1 to -25·2; p<0·0001); relative to placebo, treatment with dapagliflozin resulted in a geometric mean percentage change of -35·1% (95% CI -39·4 to -30·6; p<0·0001) in patients with type 2 diabetes and -14·8% (-22·9 to -5·9; p=0·0016) in patients without type 2 diabetes over the follow-up visits (p_interaction<0·0001) Among 3860 patients with UACR of 300 mg/g or greater at baseline, dapagliflozin increased the likelihood of regression in UACR stage (hazard ratio 1·81, 95% CI 1·60 to 2·05). Among 3820 patients with UACR less than 3000 mg/g at baseline, dapagliflozin decreased the risk of progression in UACR stage (0·41, 0·32 to 0·52). Larger reductions in UACR at day 14 during dapagliflozin treatment were significantly associated with attenuated eGFR decline during subsequent follow-up (β per log unit UACR change -3·06, 95% CI -5·20 to -0·90; p=0·0056).

INTERPRETATION

In patients with chronic kidney disease with and without type 2 diabetes, dapagliflozin significantly reduced albuminuria, with a larger relative reduction in patients with type 2 diabetes. The similar effects of dapagliflozin on clinical outcomes in patients with or without type 2 diabetes, but different effects on UACR, suggest that part of the protective effect of dapagliflozin in patients with chronic kidney disease might be mediated through pathways unrelated to reduction in albuminuria.

FUNDING

AstraZeneca.

Obesity-Related Glomerulopathy: Clinical Management

Obesity-related glomerulopathy (ORG) and other obesity-associated kidney diseases pose a major challenge to the treating nephrologist. We review the benefits of weight loss and optimal management of ORG and kidney disease in the setting of obesity. Therapeutic strategies in ORG were limited mainly in the past to weight loss through lifestyle interventions and bariatric surgery, antihypertensive treatment, and renin-angiotensin-aldosterone system blockade. Current approaches to obtain the desired weight loss include novel pharmacologic therapies that have been approved for the treatment of diabetes while offering kidney protection, such as sodium-glucose cotransporter-2 inhibitors and glucagon-like peptide-1-receptor agonists. This review focuses on the nephroprotective role of the renin-angiotensin-aldosterone system blockade and of these new pharmacologic agents, and on the renal effects of bariatric surgery in chronic kidney disease.

Renoprotection with sodium-glucose cotransporter-2 inhibitors in children: Known and unknown

Sodium-glucose cotransporter-2 (SGLT2) inhibitors represent novel hypoglycemic drugs for the treatment of adult diabetes that have shown considerable potential for cardioprotection and renoprotection. This new drug can inhibit SGLT2 at the proximal tubule, increase glucosuria and natriuresis, and thus decreases the serum glucose level and blood pressure. Furthermore, the tubuloglomerular feedback activated by the natriuresis can decrease glomerular hyperfiltration, acknowledged as the main foundation of renoprotection. Several studies have confirmed the protective effects of SGLT2 inhibitors on the kidneys of adult diabetic patients and those with non-diabetic nephropathy; however, limited researches are seen in paediatric patients. In this review, we have summarized the mechanisms of action of SGLT2 inhibitors, the current experiences in adults, results of exploratory studies in children, and adverse events & obstacles of paediatric use. We further explore the potential and possible future research direction of SGLT2 inhibitors in paediatric diseases.

Pharmacokinetic/Pharmacodynamic Properties and Clinical Use of SGLT2 Inhibitors in Non-Asian and Asian Patients with Type 2 Diabetes and Chronic Kidney Disease

Chronic kidney disease is a prevalent complication of type 2 diabetes mellitus (T2DM). Sodium-glucose cotransporter type 2 inhibitors (SGLT2is) have a unique mode of action targeting the kidney. As their glucose-lowering potency declines with the reduction in estimated glomerular filtration rate, their clinical use in patients with T2DM with chronic kidney disease has been submitted to restriction. However, recent observations demonstrated that SGLT2is reduce the progression of renal impairment in patients with mild-to-moderate chronic kidney disease, with or without albuminuria. Furthermore, SGLT2is reduce the incidence of cardiovascular events in patients with T2DM at high cardiovascular risk, independently of baseline estimated glomerular filtration rate. Thus, recent guidelines recommend the prescription of SGLT2is in patients with T2DM with mild-to-moderate chronic kidney disease defined by an estimated glomerular filtration rate between ≥ 30 and < 90 mL/min/1.73 m² and/or albuminuria. The present comprehensive review describes the pharmacokinetic/pharmacodynamic properties of SGLT2is commercialised worldwide and in Japan in patients with T2DM with mild, moderate and severe chronic kidney disease. Drug exposure increases when the estimated glomerular filtration rate declines but without a clear-cut relationship with the severity of chronic kidney disease and in a rather moderate amplitude that most often does not require a dose reduction in the presence of mild-to-moderate chronic kidney disease. The urinary glucose excretion steadily declines with the reduction in estimated glomerular filtration rate. This may explain a lower effect on glucose control, yet the positive effects on body weight and blood pressure still remain. The efficacy and safety of these SGLT2is are analysed among patients with stages 3a and 3b chronic kidney disease in placebo-controlled randomised clinical trials, with almost similar results in Asian and non-Asian individuals with T2DM. In summary, there is no reason not to prescribe SGLT2is in patients with T2DM with mild-to-moderate chronic kidney disease, especially if the aim is to benefit from cardiovascular and/or renal protection.

Mechanisms of Scarring in Focal Segmental Glomerulosclerosis

BACKGROUND

Focal segmental glomerulosclerosis (FSGS) is a histologic pattern characterized by focal glomerular scarring, which often progresses to systemic and diffuse glomerulosclerosis. Previous studies have emphasized that the initiation of classic FSGS occurs in podocytes. The dysfunction and loss of podocytes have been associated with the development of proteinuria and the progression of various diseases. In addition, primary, secondary, and genetic FSGS are caused by different mechanisms of podocyte injury.

SUMMARY

The potential sources and mechanism of podocyte supplementation are the focus of our current research. Increasing attention has been paid to the role played by parietal epithelial cells (PECs) during the progression of FSGS. PECs are not only the primary influencing factors in glomerulosclerosis lesions but also have repair abilities, which remain a focus of debate. Notably, other resident glomerular cells also play significant roles in the progression of this disease.

KEY MESSAGE

In this review, we focus on the mechanism of scarring in FSGS and discuss current and potential therapeutic strategies.

A Role for SGLT-2 Inhibitors in Treating Non-diabetic Chronic Kidney Disease

In recent years, inhibitors of the sodium-glucose co-transporter 2 (SGLT2 inhibitors) have been shown to have significant protective effects on the kidney and the cardiovascular system in patients with diabetes. This effect is also manifested in chronic kidney disease (CKD) patients and is minimally due to improved glycaemic control. Starting from these positive findings, SGLT2 inhibitors have also been tested in patients with non-diabetic CKD or heart failure with reduced ejection fraction. Recently, the DAPA-CKD trial showed a significantly lower risk of CKD progression or death from renal or cardiovascular causes in a mixed population of patients with diabetic and non-diabetic CKD receiving dapagliflozin in comparison with placebo. In patients with heart failure and reduced ejection fraction, two trials (EMPEROR-Reduced and DAPA-HF) also found a significantly lower risk of reaching the secondary renal endpoint in those treated with an SGLT2 inhibitor in comparison with placebo. This also applied to patients with CKD. Apart from their direct mechanism of action, SGLT2 inhibitors have additional effects that could be of particular interest for patients with non-diabetic CKD. Among these, SGLT2 inhibitors reduce blood pressure and serum acid uric levels and can increase hemoglobin levels. Some safety issues should be further explored in the CKD population. SGLT2 inhibitors can minimally increase potassium levels, but this has not been shown by the CREDENCE trial. They also increase magnesium and phosphate reabsorption. These effects could become more significant in patients with advanced CKD and will need monitoring when these agents are used more extensively in the CKD population. Conversely, they do not seem to increase the risk of acute kidney injury.

Sodium-glucose cotransporter 2 inhibition in non-diabetic kidney disease

PURPOSE OF REVIEW

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have proven cardiorenal protection in patients with diabetes and chronic kidney disease (CKD) as seen in cardiovascular outcome trials (CVOTs) and CREDENCE. In this review, we aim to discuss the mechanisms of kidney protection with SGLT2 inhibition as well as review the results of multiple translational studies and clinical trials of SGLT2 inhibition in the nondiabetic kidney disease (non-DKD) population.

RECENT FINDINGS

The application of SGLT2 inhibitors as dedicated kidney-protective agents continues to evolve with the publication of the dapagliflozin in patients with chronic kidney disease (DAPA CKD) trial, which extends their cardiorenal protection to patients with nondiabetic CKD. This trial was preceded by CREDENCE, a dedicated kidney outcome study in participants with DKD that demonstrated a 30% reduction in the risk of the composite kidney outcome. From a physiological perspective, mechanistic benefits of SGLT2 inhibitors are independent of their glucose-lowering effects as demonstrated in preclinical studies and post hoc analyses of dedicated CVOTs in participants with type 2 diabetes. From a clinical perspective, there is a growing body of evidence for kidney protection in nondiabetes mellitus patients.

SUMMARY

There exists strong rationale for SGLT2 inhibition to be incorporated into standard of care for appropriate groups of patients with nondiabetic kidney disease.

Use of Anti-Diabetic Agents in Non-Diabetic Kidney Disease: From Bench to Bedside

New drugs were recently developed to treat hyperglycemia in patients with type 2 diabetes mellitus (T2D). However, metformin remains the first-line anti-diabetic agent because of its cost-effectiveness. It has pleiotropic action that produces cardiovascular benefits, and it can be useful in diabetic nephropathy, although metformin-associated lactic acidosis is a hindrance to its use in patients with kidney failure. New anti-diabetic agents, including glucagon-like peptide-1 receptor (GLP-1R) agonists, dipeptidyl peptidase-4 (DPP-4) inhibitors, and sodium-glucose transporter-2 (SGLT-2) inhibitors, also produce cardiovascular or renal benefits in T2D patients. Their glucose-independent beneficial actions can lead to cardiorenal protection via hemodynamic stabilization and inflammatory modulation. Systemic hypertension is relieved by natriuresis and improved vascular dysfunction. Enhanced tubuloglomerular feedback can be restored by SGLT-2 inhibition, reducing glomerular hypertension. Patients with non-diabetic kidney disease might also benefit from those drugs because hypertension, proteinuria, oxidative stress, and inflammation are common factors in the progression of kidney disease, irrespective of the presence of diabetes. In various animal models of non-diabetic kidney disease, metformin, GLP-1R agonists, DPP-4 inhibitors, and SGLT-2 inhibitors were favorable to kidney morphology and function. They strikingly attenuated biomarkers of oxidative stress and inflammatory responses in diseased kidneys. However, whether those animal results translate to patients with non-diabetic kidney disease has yet to be evaluated. Considering the paucity of new agents to treat kidney disease and the minimal adverse effects of metformin, GLP-1R agonists, DPP-4 inhibitors, and SGLT-2 inhibitors, these anti-diabetic agents could be used in patients with non-diabetic kidney disease. This paper provides a rationale for clinical trials that apply metformin, GLP-1R agonists, DPP-4 inhibitors, and SGLT-2 inhibitors to non-diabetic kidney disease.

Glomerular Diseases in Diabetic Patients: Implications for Diagnosis and Management

The prevalence of diabetes continues to rise worldwide. In addition to rising rates of diabetic kidney disease, we are also seeing a parallel rise in nondiabetic kidney disease among patients with diabetes. These nondiabetic lesions include focal segmental glomerulosclerosis, IgA nephropathy, membranous nephropathy, and other glomerular diseases. The management of diabetic kidney disease is rapidly evolving to include, beyond glycemic control and renin angiotensin inhibition, the use of sodium-glucose cotransporter 2 (SGLT2) inhibitors and mineralocorticoid receptor antagonists. These and other new treatment strategies should be applicable to managing glomerular disease in diabetic patients to reduce toxicities associated with immunosuppression and, in particular, corticosteroids. The prevalence of glomerular disease in diabetic patients is underappreciated. Diagnosis and appropriately treating these diseases remain an important avenue to modify kidney outcomes in diabetic patients.

Angiotensin II up-regulates sodium-glucose co-transporter 2 expression and SGLT2 inhibitor attenuates Ang II-induced hypertensive renal injury in mice

Clinical trials indicate that sodium/glucose co-transporter 2 (SGLT2) inhibitors (SGLT2i) improve kidney function, yet, the molecular regulation of SGLT2 expression is incompletely understood. Here, we investigated the role of the intrarenal renin-angiotensin system (RAS) on SGLT2 expression. In adult non-diabetic participants in the Nephrotic Syndrome Study Network (NEPTUNE, n=163), multivariable linear regression analysis showed SGLT2 mRNA was significantly associated with angiotensinogen (AGT), renin, and angiotensin-converting enzyme (ACE) mRNA levels (P<0.001). In vitro, angiotensin II (Ang II) dose-dependently stimulated SGLT2 expression in HK-2, human immortalized renal proximal tubular cells (RPTCs); losartan and antioxidants inhibited it. Sglt2 expression was increased in transgenic (Tg) mice specifically overexpressing Agt in their RPTCs, as well as in WT mice with a single subcutaneous injection of Ang II (1.44 mg/kg). Moreover, Ang II (1000 ng/kg/min) infusion via osmotic mini-pump in WT mice for 4 weeks increased systolic blood pressure (SBP), glomerulosclerosis, tubulointerstitial fibrosis, and albuminuria; canaglifozin (Cana, 15 mg/kg/day) reversed these changes, with the exception of SBP. Fractional glucose excretion (FeGlu) was higher in Ang II+Cana than WT+Cana, whereas Sglt2 expression was similar. Our data demonstrate a link between intrarenal RAS and SGLT2 expression and that SGLT2i ameliorates Ang II-induced renal injury independent of SBP.

The Rationale and Evidence for SGLT2 Inhibitors as a Treatment for Nondiabetic Glomerular Disease

Background

Recent studies show that sodium-glucose cotransporter 2 inhibitors (SGLT2i), originally approved for glycemic control in patients with type 2 diabetes, also exert renoprotective effects independently from effects on dysglycemia. Moreover, recent work indicates that SGLT2i treatment may be effective in patients with nondiabetic chronic kidney disease, including primary and secondary glomerular diseases.

Summary

SGLT2i lower blood glucose by blocking glucose resorption in the early renal proximal tubule through the glucose transporter, SGLT2, leading to enhanced urinary glucose excretion. Recent studies indicate that SGLT2i may have pleiotropic effects on cells other than proximal tubular cells. SGLT2i reduce the glomerular workload by decreasing the intraglomerular pressure, thus ameliorating hyperfiltration, if present, and may also decrease systemic blood pressure. SGLT2i may also act directly on endothelial cells, possibly via modulating the effects of adhesion molecules and reducing inflammatory cytokines and reactive oxygen species. SGLT2i may have direct anti-inflammatory and antifibrotic effects on renal tubules. Some reports suggest direct protective effects on podocytes and mesangial cells as well. Here, we provide a review of the potential mechanisms of renoprotection, therapeutic utility, and potential side effects of SGLT2i in patients with nondiabetic glomerular diseases, based on data from studies carried out in cells, experimental animals, and humans.

Key Messages

SGLT2i may be a promising addition to the glomerular disease treatment armamentarium. However, it is unclear at what point of the natural history of specific glomerular diseases (whether this is immune or nonimmune mediated) SGLT2i can be beneficial. Additionally, further studies are needed to assess the long-term efficacy and safety of SGLT2i in patients with nondiabetic glomerular diseases.

Glomerular hyperfiltration with hyperglycemia in the spontaneously diabetic Torii (SDT) fatty rat, an obese type 2 diabetic model

Glomerular hyperfiltration is observed in an early stage of kidney diseases including diabetic nephropathy. A better understanding of pathophysiological changes in glomerular hyperfiltration is essential for development of new therapies to prevent kidney disease progression. In this study, we investigated glomerular changes including glomerular filtration rate (GFR) and glomerular size in the Spontaneously Diabetic Torii (SDT) fatty rat, an obese type 2 diabetic model, and we also evaluated pharmacological effects of the sodium glucose cotransporter 2 inhibitor dapagliflozin on the renal lesions. Dapagliflozin was administered to SDT fatty rats from 5 to 17 weeks of age. Blood and urinary biochemical parameters were periodically measured. GFR was determined by transdermal GFR monitor at 16 weeks of age and histopathological analysis was performed at 17 weeks of age. SDT fatty rat developed severe hyperglycemia and exhibited pathophysiological abnormalities in the kidney, such as an increased GFR, glomerular hypertrophy and tissue lesions. Dapagliflozin achieved good glycemic control during the experimental period, inhibited the increase in GFR, and improved histopathological abnormalities in tubules. These results suggest that the SDT fatty rat is a useful model for analyzing the pathogenesis of diabetic nephropathy during its early stage and dapagliflozin improves not only hyperglycemia but also glomerular hyperfiltration and tubule lesions in SDT fatty rat.

Sodium-glucose cotransporter 2 inhibitors: extending the indication to non-diabetic kidney disease?

This year the medical community was pleasantly surprised by the results of the first large outcome trial that primarily examined the renal effects of the sodium-glucose cotransporter 2 (SGLT2) inhibitor canagliflozin (CANA) in subjects with diabetes and impaired kidney function. The Evaluation of the Effects of Canagliflozin on Renal and Cardiovascular Outcomes in Participants With Diabetic Nephropathy (CREDENCE) trial showed that CANA, relative to placebo, reduces the risk for end-stage renal disease, doubling of creatinine or renal death by 34% [hazard ratio 0.66 (95% confidence interval 0.53–0.81]. These effects were consistent across baseline estimated glomerular filtration rate (eGFR) and haemoglobin A1c subgroups. In this review we combine the results of the CREDENCE trial with those of several cardiovascular outcome trials with SGLT2 inhibitors and show that, unexpectedly, patients with lower eGFR levels may have greater benefit with respect to cardiovascular outcome than patients with normal kidney function. The cardio- and renoprotective effects of SGLT2 inhibitors seem to be independent of their glucose-lowering effects, as shown in several post hoc analyses. In this review we discuss the alleged mechanisms of action that explain the beneficial effects of this novel class of drugs. Moreover, we discuss whether these findings indicate that this class of drugs may also be beneficial in non-diabetic chronic kidney diseases.

SGLT2 Inhibitors and Kidney Outcomes in Patients with Chronic Kidney Disease

Globally, diabetes mellitus is a leading cause of kidney disease, with a critical percent of patients approaching end-stage kidney disease. In the current era, sodium-glucose co-transporter 2 inhibitors (SGLT2i) have emerged as phenomenal agents in halting the progression of kidney disease. Positive effects of SGLT2i are centered on multiple mechanisms, including glycosuric effects, tubule-glomerular feedback, antioxidant, anti-fibrotic, natriuretic, and reduction in cortical hypoxia, alteration in energy metabolism. Concurrently, multiple kidney and cardiovascular outcome studies have reported remarkable advantages of SGLT2i including mortality benefits. Additionally, the superiority of combination therapies (SGLT2I along with metformin/DDP-4 Inhibitors) in treatment-naïve diabetic patients is further looked into with potential signal towards glycemic and blood pressure control. Reported promising results initiate a gateway for future research targeting kidney outcomes with combination therapies as an initial approach. In the current paper, we summarize leading cardiovascular and kidney outcome trials in patients with type 2 diabetes, the role of SGLT2i in non-diabetic proteinuric kidney disease, and the potential mechanisms of action of SGLT2i with special focus on combination therapy as an initial therapeutic approach in treatment-naïve diabetic patients.

Emerging drugs for treatment of focal segmental glomerulosclerosis

BACKGROUND

Glomerulosclerosis represents the final stage of glomerular injury during the course of kidney disease and can result from a primary disturbance in disorders like focal segmental glomerulosclerosis or a secondary response to tubulointerstitial disease. Overall, primary focal glomerulosclerosis (FSGS), the focus of this review, accounts for 10-20% of patients of all ages who progress to end stage kidney disease. There are no FDA approved therapeutic options that effectively prevent or delay the onset of kidney failure.

AREAS COVERED

Current immunosuppressive therapy and conservative management including inhibitors of the renin-angiotensin-aldosterone axis and sodium-glucose cotransporter are reviewed. FSGS is now recognized to represent a heterogeneous entity with multiple underlying disease mechanisms. Therefore, novel approaches targeting the podocyte cytoskeleton, immunological, inflammatory, hemodynamic and metabolic pathways are highlighted.

EXPERT OPINION

A number of factors are driving the development of drugs to treat focal segmental glomerulosclerosis in particular and glomerulosclerosis in general including growing awareness of the burden of chronic kidney disease, improved scientific understanding of the mechanism of injury, and the development of noninvasive profiles to identify subgroups of patients with discrete mechanisms of glomerular injury.

Effects of the SGLT2 inhibitor dapagliflozin on proteinuria in non-diabetic patients with chronic kidney disease (DIAMOND): a randomised, double-blind, crossover trial

BACKGROUND

SGLT2 inhibition decreases albuminuria and reduces the risk of kidney disease progression in patients with type 2 diabetes. These benefits are unlikely to be mediated by improvements in glycaemic control alone. Therefore, we aimed to examine the kidney effects of the SGLT2 inhibitor dapagliflozin in patients with proteinuric kidney disease without diabetes.

METHODS

DIAMOND was a randomised, double-blind, placebo-controlled crossover trial done at six hospitals in Canada, Malaysia, and the Netherlands. Eligible participants were adult patients (aged 18-75 years) with chronic kidney disease, without a diagnosis of diabetes, with a 24-h urinary protein excretion greater than 500 mg and less than or equal to 3500 mg and an estimated glomerular filtration rate (eGFR) of at least 25 mL/min per 1·73 m², and who were on stable renin-angiotensin system blockade. Participants were randomly assigned (1:1) to receive placebo and then dapagliflozin 10 mg per day or vice versa. Each treatment period lasted 6 weeks with a 6-week washout period in between. Participants, investigators, and study personnel were masked to assignment throughout the trial and analysis. The primary outcome was percentage change from baseline in 24-h proteinuria during dapagliflozin treatment relative to placebo. Secondary outcomes were changes in measured GFR (mGFR; via iohexol clearance), bodyweight, blood pressure, and concentrations of neurohormonal biomarkers. Analyses were done in accordance with the intention-to-treat principle. This study is registered with ClinicalTrials.gov, NCT03190694.

FINDINGS

Between Nov 22, 2017, and April 5, 2019, 58 patients were screened, of whom 53 (mean age 51 years [SD 13]; 32% women) were randomly assigned (27 received dapagliflozin then placebo and 26 received placebo then dapagliflozin). One patient discontinued during the first treatment period. All patients were included in the analysis. Mean baseline mGFR was 58·3 mL/min per 1·73 m² (SD 23), median proteinuria was 1110 mg per 24 h (IQR 730-1560), and mean HbA_1c was 5·6% (SD 0·4). The difference in mean proteinuria change from baseline between dapagliflozin and placebo was 0·9% (95% CI -16·6 to 22·1; p=0·93). Compared with placebo, mGFR was changed with dapagliflozin treatment by -6·6 mL/min per 1·73 m² (-9·0 to -4·2; p<0·0001) at week 6. This reduction was fully reversible within 6 weeks after dapagliflozin discontinuation. Compared with placebo, bodyweight was reduced by 1·5 kg (0·03-3·0; p=0·046) with dapagliflozin; changes in systolic and diastolic blood pressure and concentrations of neurohormonal biomarkers did not differ significantly between dapagliflozin and placebo treatment. The numbers of patients who had one or more adverse events during dapagliflozin treatment (17 [32%] of 53) and during placebo treatment (13 [25%] of 52) were similar. No hypoglycaemic events were reported and no deaths occurred.

INTERPRETATION

6-week treatment with dapagliflozin did not affect proteinuria in patients with chronic kidney disease without diabetes, but did induce an acute and reversible decline in mGFR and a reduction in bodyweight. Long-term clinical trials are underway to determine whether SGLT2 inhibitors can safely reduce the rate of major clinical kidney outcomes in patients with chronic kidney disease with and without diabetes.

FUNDING

AstraZeneca.

A unifying model of glucotoxicity in human renal proximal tubular epithelial cells and the effect of the SGLT2 inhibitor dapagliflozin

BACKGROUND

Glucotoxicity in renal tubular epithelial cells (RPTECs) contributes to the pathogenesis of diabetic nephropathy. Sodium-glucose cotransporter 2 (SGLT2) inhibitors may exert their renoprotective effect by preventing glucotoxicity. We tested whether the confirmed in capillary endothelial cells unifying model of glucotoxicity can be applied in RPTECs and the impact of dapagliflozin.

METHODS

In primary human RPTECs cultured in normal or high glucose medium in the presence or not of dapagliflozin, we assessed glucose consumption, SCLT2 expression, reactive oxygen species (ROS) production, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) activity, D-sorbitol and methylglyoxal cell content, O-linked β-N-acetyl glucosamine (O-Glc-NAc)-modified proteins, protein kinase C (PKC) activity, transforming growth factor-β1 (TGF-β1), interleukin-8 (IL-8), cell necrosis, and cell apoptosis using colorimetric and immunoenzymatic assays, and western blotting.

RESULTS

High glucose increases SGLT2 expression and glucose consumption. ROS are overproduced, and GAPDH is inhibited. The accumulation due to GAPDH inhibition glycolytic products are diverted into four noxious pathways. The polyol pathway assessed by D-sorbitol, the hexosamine pathway determined by O-GlcNAc-modified proteins, the lipid synthesis pathway assessed by PKC activity, and the advanced glycation end-products (AGEs) formation assessed by methylglyoxal. Eventually, these paths lead to overproduction of TGF-β1 and IL-8, as well as to cell necrosis and apoptosis. Dapagliflozin ameliorates all the above cascade of events.

CONCLUSIONS

Our results support a unifying model for glucotoxicity in RPTECs. Dapagliflozin by decreasing the elevated glucose influx into the RPTECs under high glucose conditions ameliorates glucotoxicity.

The New Biology of Diabetic Kidney Disease-Mechanisms and Therapeutic Implications

Diabetic kidney disease remains the most common cause of end-stage kidney disease in the world. Despite reductions in incidence rates of myocardial infarction and stroke in people with diabetes over the past 3 decades, the risk of diabetic kidney disease has remained unchanged, and may even be increasing in younger individuals afflicted with this disease. Accordingly, changes in public health policy have to be implemented to address the root causes of diabetic kidney disease, including the rise of obesity and diabetes, in addition to the use of safe and effective pharmacological agents to prevent cardiorenal complications in people with diabetes. The aim of this article is to review the mechanisms of pathogenesis and therapies that are either in clinical practice or that are emerging in clinical development programs for potential use to treat diabetic kidney disease.

What have we learned about renal protection from the cardiovascular outcome trials and observational analyses with SGLT2 inhibitors?

Over the past 5 years, sodium-glucose cotransport 2 (SGLT2) inhibitors have been increasingly regarded as glycaemic agents with cardiovascular (CV) and renal protective effects. The CV benefits of SGLT2 inhibitors have been well established in patients with type 2 diabetes (T2D) and a range of CV comorbidities at baseline. Subsequently, the renal benefits of SGLT2 inhibitors were established in the CREDENCE trial, a dedicated renal outcome trial where canagliflozin reduced the primary composite renal outcome by 30%. In light of these trials, clinical practice guidelines have rapidly evolved, recommending the use of SGLT2 inhibitors as renal and cardioprotective agents in appropriate patient populations. Accordingly, it is important to have an in-depth understanding of the evidence underlying the use of SGLT2 inhibitors in patients with T2D based on published clinical trials and real-world evidence (RWE) studies, as well as information related to potential safety concerns. To accomplish this, we reviewed the evidence for renal protection and safety with SGLT2 inhibitors in the EMPA-REG OUTCOME, CANVAS Program and DECLARE-TIMI 58 CV safety trials, and in the growing body of evidence emerging from real-world studies. This body of work has shown that SGLT2 inhibitors reduce the risk of surrogate renal endpoints such as albuminuria and mitigate the risk of hard renal endpoints including doubling of serum creatinine and end-stage kidney disease in patients with T2D.

Management and treatment of glomerular diseases (part 1): conclusions from a kidney disease: improving global outcomes (KDIGO) controversies conference

The Kidney Disease: Improving Global Outcomes (KDIGO) initiative organized a Controversies Conference on glomerular diseases in November 2017. The conference focused on the 2012 KDIGO guideline with the aim of identifying new insights into nomenclature, pathogenesis, diagnostic work-up, and, in particular, therapy of glomerular diseases since the guideline’s publication. It was the consensus of the group that most guideline recommendations, in particular those dealing with therapy, will need to be revisited by the guideline-updating Work Group. This report covers general management of glomerular disease, IgA nephropathy, and membranous nephropathy.

Management and treatment of glomerular diseases (part 1): conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

The Kidney Disease: Improving Global Outcomes (KDIGO) initiative organized a Controversies Conference on glomerular diseases in November 2017. The conference focused on the 2012 KDIGO guideline with the aim of identifying new insights into nomenclature, pathogenesis, diagnostic work-up, and, in particular, therapy of glomerular diseases since the guideline's publication. It was the consensus of the group that most guideline recommendations, in particular those dealing with therapy, will need to be revisited by the guideline-updating Work Group. This report covers general management of glomerular disease, IgA nephropathy, and membranous nephropathy.