Role of Sodium-Glucose Co-Transporter-2 Inhibitor During Anthracycline Use: An Updated Review

The coalescence of anthracycline-induced cardiotoxicity and the evolving role of sodium-glucose co-transporter-2 (SGLT-2) inhibitors in oncology and cardiology has prompted a comprehensive review of their mechanisms, clinical implications, and future directions. Anthracyclines, potent chemotherapeutic agents, have been integral in cancer treatment, yet their potential for cardiac harm necessitates careful monitoring and management. We explore the multifactorial nature of anthracycline-induced cardiotoxicity, encompassing diverse patient populations, cumulative doses, and interplay with other treatments. While advancements in imaging and biomarker assessments aid in early detection, the lack of standardized criteria poses challenges. The emergent role of SGLT-2 inhibitors, initially developed for diabetes management, presents a novel avenue for cardioprotection. Beyond glycemic control, these inhibitors exhibit pleiotropic effects, including enhanced diuresis, anti-inflammatory actions, and modulation of energy sources. Consequently, SGLT-2 inhibitors are being investigated for their potential to mitigate cardiotoxic effects, promising an innovative approach in cardio-oncology. Despite these advancements, limitations in data interpretation and patient-specific considerations persist. The future of anthracycline-induced cardiotoxicity research lies in predictive biomarkers, precision medicine, multidisciplinary collaboration, and tailored treatment regimens. By navigating these challenges and harnessing emerging strategies, we aim to optimize cancer treatment efficacy while safeguarding cardiovascular health, ultimately paving the way for a new era of personalized and comprehensive oncologic care.

Excess dietary sugar impairs Drosophila adult stem cells via elevated reactive oxygen species-induced JNK signaling

High-sugar diets (HSDs) often lead to obesity and type 2 diabetes, both metabolic syndromes associated with stem cell dysfunction. However, it is unclear whether excess dietary sugar affects stem cells. Here, we report that HSD impairs stem cell function in the intestine and ovaries of female Drosophila prior to the onset of insulin resistance, a hallmark of type 2 diabetes. Although 1 week of HSD leads to obesity, impaired oogenesis and altered lipid metabolism, insulin resistance does not occur. HSD increases glucose uptake by germline stem cells (GSCs) and triggers reactive oxygen species-induced JNK signaling, which reduces GSC proliferation. Removal of excess sugar from the diet reverses these HSD-induced phenomena. A similar phenomenon is found in intestinal stem cells (ISCs), except that HSD disrupts ISC maintenance and differentiation. Interestingly, tumor-like GSCs and ISCs are less responsive to HSD, which may be because of their dependence on glycolytic metabolism and high energy demand, respectively. This study suggests that excess dietary sugar induces oxidative stress and damages stem cells before insulin resistance develops, a mechanism that may also occur in higher organisms.

Improved Glycaemic Control and Nephroprotective Effects of Empagliflozin and Paricalcitol Co-Therapy in Mice with Type 2 Diabetes Mellitus

Herein, we measured the antidiabetic and nephroprotective effects of the sodium-glucose cotransporter-2 inhibitor (empagliflozin; SGLT2i) and synthetic active vitamin D (paricalcitol; Pcal) mono- and co-therapy against diabetic nephropathy (DN). Fifty mice were assigned into negative (NC) and positive (PC) control, SGLT2i, Pcal, and SGLT2i+Pcal groups. Following establishment of DN, SGLT2i (5.1 mg/kg/day) and/or Pcal (0.5 µg/kg/day) were used in the designated groups (5 times/week/day). DN was affirmed in the PC group by hyperglycaemia, dyslipidaemia, polyuria, proteinuria, elevated urine protein/creatinine ratio, and abnormal renal biochemical parameters. Renal SREBP-1 lipogenic molecule, adipokines (leptin/resistin), pro-oxidant (MDA/H2O2), pro-inflammatory (IL1β/IL6/TNF-α), tissue damage (iNOS/TGF-β1/NGAL/KIM-1), and apoptosis (TUNEL/Caspase-3) markers also increased in the PC group. In contrast, renal lipolytic (PPARα/PPARγ), adiponectin, antioxidant (GSH/GPx1/SOD1/CAT), and anti-inflammatory (IL10) molecules decreased in the PC group. Both monotherapies increased insulin levels and mitigated hyperglycaemia, dyslipidaemia, renal and urine biochemical profiles alongside renal lipid regulatory molecules, inflammation, and oxidative stress. While SGLT2i monotherapy showed superior effects to Pcal, their combination demonstrated enhanced remedial actions related to metabolic control alongside renal oxidative stress, inflammation, and apoptosis. In conclusion, SGLT2i was better than Pcal monotherapy against DN, and their combination revealed better nephroprotection, plausibly by enhanced glycaemic control with boosted renal antioxidative and anti-inflammatory mechanisms.

Wild Rosa roxburghii Tratt Juices Grown at Different Altitudes Regulate Blood Glucose in Type 1 Diabetic Mice via the PI3K/Akt Pathway

To explore hypoglycemic effect of wild Rosa roxburghii tratt (RRT) juice at different altitudes on type 1 diabetes mellitus (T1DM). The T1DM mouse model was induced by streptozotocin (STZ), and the experiment included a normal group (NC), model group (MC), wild RRT juice groups high (HF), medium (MF), low altitude (DF) and cultivated control group (PC). During experiment, food intake, water intake, body weight, and fasting blood glucose were measured. After 28 days of administration, glucose tolerance, glycogen level, lipid profiles, and antioxidation levels in serum and liver were measured, and histomorphological changes of liver and kidney were observed by hematoxylin and eosin staining. The results showed that wild RRT juice reduced blood glucose level, alleviated liver and kidney tissue damage, improved glucose and lipid metabolism disorders and attenuated oxidative damage in T1DM mice. Western blot showed that wild RRT juice at grown at different altitudes significantly increased protein abundance of PI3K, Akt, and GLUT2 in liver of T1DM mice. In conclusion, wild RRT juice from different altitudes improved glucose and lipid metabolism disorders and oxidative damage in T1DM mice, which may be attributed to activation of PI3K/Akt pathway. Overall effect: MF > PC > HF > DF.

Sodium Magnetic Resonance Imaging Shows Impairment of the Counter-current Multiplication System in Diabetic Mice Kidney

Key Points

23Na MRI allows us to noninvasively assess sodium distribution. We propose the utility of 23Na MRI for evaluating functional changes in diabetic kidney disease and not as a marker reflecting structural damage. 23Na MRI may be an early marker for structures beyond the glomeruli, enabling prompt intervention with novel efficacious tubule-targeting therapies.

Background

Sodium magnetic resonance imaging can noninvasively assess sodium distribution, specifically sodium concentration in the countercurrent multiplication system in the kidney, which forms a sodium concentration gradient from the cortex to the medulla, enabling efficient water reabsorption. This study aimed to investigate whether sodium magnetic resonance imaging can detect changes in sodium concentrations under normal conditions in mice and in disease models, such as a mouse model with diabetes mellitus.

Methods

We performed sodium and proton nuclear magnetic resonance imaging using a 9.4-T vertical standard-bore superconducting magnet.

Results

A condition of deep anesthesia, with widened breath intervals, or furosemide administration in 6-week-old C57BL/6JJcl mice showed a decrease in both tissue sodium concentrations in the medulla and sodium concentration gradients from the cortex to the medulla. Furthermore, sodium magnetic resonance imaging revealed reductions in the sodium concentration in the medulla and in the gradient from the cortex to the medulla in BKS.Cg-Leprdb+/+ Leprdb/Jcl mice at very early type 2 diabetes mellitus stages compared with corresponding control BKS.Cg-m+/m+/Jcl mice.

Conclusions

The kidneys of BKS.Cg-Leprdb+/+ Leprdb/Jcl mice aged 6 weeks showed impairments in the countercurrent multiplication system. We propose the utility of 23Na MRI for evaluating functional changes in diabetic kidney disease and not as a marker that reflects structural damage. Thus, 23Na MRI may be a potentially very early marker for structures beyond the glomerulus; this may prompt intervention with novel efficacious tubule-targeting therapies.

Kidney Proximal Tubule GLUT2-More than Meets the Eye

Tubulopathy plays a central role in the pathophysiology of diabetic kidney disease (DKD). Under diabetic conditions, the kidney proximal tubule cells (KPTCs) are exposed to an extensive amount of nutrients, most notably glucose; these nutrients deteriorate KPTCs function and promote the development and progression of DKD. Recently, the facilitative glucose transporter 2 (GLUT2) in KPTCs has emerged as a central regulator in the pathogenesis of DKD. This has been demonstrated by identifying its specific role in enhancing glucose reabsorption and glucotoxicity, and by deciphering its effect in regulating the expression of the sodium-glucose transporter 2 (SGLT2) in KPTCs. Moreover, reduction/deletion of KPTC-GLUT2 has been recently found to ameliorate DKD, raising the plausible idea of considering it as a therapeutic target against DKD. However, the underlying molecular mechanisms by which GLUT2 exerts its deleterious effects in KPTCs remain vague. Herein, we review the current findings on the proximal tubule GLUT2 biology and function under physiologic conditions, and its involvement in the pathophysiology of DKD. Furthermore, we shed new light on its cellular regulation during diabetic conditions.

The sugar daddy: the role of the renal proximal tubule in glucose homeostasis

Renal blood flow represents >20% of total cardiac output and with this comes the great responsibility of maintaining homeostasis through the intricate regulation of solute handling. Through the processes of filtration, reabsorption, and secretion, the kidneys ensure that solutes and other small molecules are either returned to circulation, catabolized within renal epithelial cells, or excreted through the process of urination. Although this occurs throughout the renal nephron, one segment is tasked with the bulk of solute reabsorption-the proximal tubule. Among others, the renal proximal tubule is entirely responsible for the reabsorption of glucose, a critical source of energy that fuels the body. In addition, it is the only other site of gluconeogenesis outside of the liver. When these processes go awry, pathophysiological conditions such as diabetes and acidosis result. In this review, we highlight the recent advances made in understanding these processes that occur within the renal proximal tubule. We focus on the physiological mechanisms at play regarding glucose reabsorption and glucose metabolism, emphasize the conditions that occur under diseased states, and explore the emerging class of therapeutics that are responsible for restoring homeostasis.

Opposite physiological and pathological mTORC1-mediated roles of the CB1 receptor in regulating renal tubular function

Activation of the cannabinoid-1 receptor (CB₁R) and the mammalian target of rapamycin complex 1 (mTORC1) in the renal proximal tubular cells (RPTCs) contributes to the development of diabetic kidney disease (DKD). However, the CB₁R/mTORC1 signaling axis in the kidney has not been described yet. We show here that hyperglycemia-induced endocannabinoid/CB₁R stimulation increased mTORC1 activity, enhancing the transcription of the facilitative glucose transporter 2 (GLUT2) and leading to the development of DKD in mice; this effect was ameliorated by specific RPTCs ablation of GLUT2. Conversely, CB₁R maintained the normal activity of mTORC1 by preventing the cellular excess of amino acids during normoglycemia. Our findings highlight a novel molecular mechanism by which the activation of mTORC1 in RPTCs is tightly controlled by CB₁R, either by enhancing the reabsorption of glucose and inducing kidney dysfunction in diabetes or by preventing amino acid uptake and maintaining normal kidney function in healthy conditions.

Renal proximal tubules modulate whole-body homeostasis by sensing various nutrients. Here the authors describe the existence and importance of a unique CB1/mTORC1/GLUT2 signaling axis in regulating nutrient homeostasis in healthy and diseased kidney.

HNF1A Mutations and Beta Cell Dysfunction in Diabetes

Understanding the genetic factors of diabetes is essential for addressing the global increase in type 2 diabetes. HNF1A mutations cause a monogenic form of diabetes called maturity-onset diabetes of the young (MODY), and HNF1A single-nucleotide polymorphisms are associated with the development of type 2 diabetes. Numerous studies have been conducted, mainly using genetically modified mice, to explore the molecular basis for the development of diabetes caused by HNF1A mutations, and to reveal the roles of HNF1A in multiple organs, including insulin secretion from pancreatic beta cells, lipid metabolism and protein synthesis in the liver, and urinary glucose reabsorption in the kidneys. Recent studies using human stem cells that mimic MODY have provided new insights into beta cell dysfunction. In this article, we discuss the involvement of HNF1A in beta cell dysfunction by reviewing previous studies using genetically modified mice and recent findings in human stem cell-derived beta cells.

Potential impacts of diabetes mellitus and anti-diabetes agents on expressions of sodium-glucose transporters (SGLTs) in mice

PURPOSE

Sodium-glucose transporters (SGLTs) are important targets for therapeutic intervention of type 2 diabetes. This study aims to evaluate the physiological influences of diabetes mellitus and the potential impacts of metformin and fluoxetine on SGLTs expressions.

METHODS

Alterations of SGLT1 and SGLT2 were measured in organs involved in glucose homeostasis (kidney, intestine, liver and pancreas) of streptozotocin (STZ) and high-fat diet (HFD) induced diabetic mice by western blotting and real-time PCR (RT-PCR) respectively.

RESULTS

In kidney, duodenal segments of intestine, liver, and pancreas of HFD diabetic mice, expressions of SGLT2 were all elevated compared to control mice. The level of SGLT1 was significantly increased in intestine, but was decreased in pancreas. SGLT1 expression in kidney was unaffected, and SGLT1 was undetectable in hepatocytes. Similar results were obtained in STZ diabetic mice. More importantly, here we noticed metformin decreased levels of SGLT2 in kidney, intestine, and pancreas of HFD mice markedly. Expressions of SGLT1 in intestine and pancreas were reduced by metformin as well. In contrast, fluoxetine increased abundances of SGLT2 and SGLT1 in kidney of HFD mice, but decreased SGLT1 expression in intestine.

CONCLUSIONS

The present study provided evidence that expressions of SGLT1 and SGLT2 were significantly modulated by diabetes mellitus as well as by metformin and fluoxetine, which indicated the efficacy of SGLT2 inhibitors might be impacted by these factors.

Renal lipid accumulation induced by high-fat diet regulates glucose homeostasis via sodium-glucose cotransporter 2

AIMS

Visceral lipid accumulation is involved in a variety of physiological aberrations. In the current study, we aimed to investigate whether lipid accumulation had an impact on glucose reabsorption in the kidney.

METHODS

We examined renal lipid content and renal threshold for glucose (RT_G) of each subject. We compared sodium-glucose cotransporter 2 (SGLT2) and sterol regulatory element-binding protein 1c (SREBP1c) levels in kidneys between rats fed with high fat diet (HFD) and normal chow diet. In vitro, HK2 cells were treated with palmitic acid (PA). Intracellular lipid droplet deposition, glucose uptake, SGLT2 and SREBP1c expression were examined.

RESULTS

Renal fat fraction was positively associated with RT_G among the recruited subjects. Moreover, renal lipid content was significantly increased in HFD rats, as well as SGLT2 expression. Accompanied with lipid droplet deposition in HK2 cells, PA stimulated SGLT2 expression and glucose uptake. In addition, after PA treatment, SREBP1c expression was significantly enhanced. However, transfection with siRNA-SREBP1c resulted in significant amelioration of lipid accumulation induced by PA in HK2 cells. Further examination indicated that accompanied with improvement of lipid deposition, SGLT2 expression and glucose uptake were attenuated.

CONCLUSIONS

The results of our study demonstrate the involvement of renal lipid accumulation in glucose homeostasis.

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

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

Cannabinoid Receptor 1 Inhibition in Chronic Kidney Disease: A New Therapeutic Toolbox

Chronic kidney disease (CKD) concerns millions of individuals worldwide, with few therapeutic strategies available to date. Recent evidence suggests that the endocannabinoid system (ECS) could be a new therapeutic target to prevent CKD. ECS combines receptors, cannabinoid receptor type 1 (CB1R) and type 2 (CB2R), and ligands. The most prominent receptor within the kidney is CB1R, its endogenous local ligands being anandamide and 2-arachidonoylglycerol. Therefore, the present review focuses on the therapeutic potential of CB1R and not CB2R. In the normal kidney, CB1R is expressed in many cell types, especially in the vasculature where it contributes to the regulation of renal hemodynamics. CB1R could also participate to water and sodium balance and to blood pressure regulation but its precise role remains to decipher. CB1R promotes renal fibrosis in both metabolic and non-metabolic nephropathies. In metabolic syndrome, obesity and diabetes, CB1R inhibition not only improves metabolic parameters, but also exerts a direct role in preventing renal fibrosis. In non-metabolic nephropathies, its inhibition reduces the development of renal fibrosis. There is a growing interest of the industry to develop new CB1R antagonists without central nervous side-effects. Experimental data on renal fibrosis are encouraging and some molecules are currently under early-stage clinical phases (phases I and IIa studies). In the present review, we will first describe the role of the endocannabinoid receptors, especially CB1R, in renal physiology. We will next explore the role of endocannabinoid receptors in both metabolic and non-metabolic CKD and renal fibrosis. Finally, we will discuss the therapeutic potential of CB1R inhibition using the new pharmacological approaches. Overall, the new pharmacological blockers of CB1R could provide an additional therapeutic toolbox in the management of CKD and renal fibrosis from both metabolic and non-metabolic origin.

Modulation of Calcium Homeostasis May Be Associated with Susceptibility to Renal Cell Carcinoma in Diabetic Nephropathy Rats

Introduction

Clinical studies have indicated a relationship between diabetic nephropathy (DN) and the incidence and prevalence of renal cell carcinoma (RCC). However, the mechanism linking diabetic nephropathy and renal cell carcinoma has not yet to be identified.

Methods

In this study, a total of 42 male Sprague Dawley (SD) rats were randomly assigned to a DN group (n=35) and a control group (n=7). All animals in the DN group were unilaterally nephrectomized and treated with streptozotocin with the development of blood glucose levels >16.7mmol/L and dominant proteinuria and were compared to controls without such changes. Histopathologic alterations in the kidneys were examined by HE staining and Ki-67 immunohistochemistry. Differentially expressed genes were identified and validated by RNA-seq and PCR.

Results

As the results, except for two rats that failed to develop the DN model and were excluded from the analysis, 33 rats in the DN group with overt signs of DN demonstrated significantly higher food and water intake, urine production, and urine protein and urinary protein/creatinine ratio than controls. Overall, 15.2% (n=5/33) of DN animals developed RCC while none tumors were observed in the control group (n=0/7). RNA-seq analysis in these animals indicated different TRPV5 gene expression and calcium pathway expression in DN animals with developing tumors, when compared with animals with no obvious tumors. In addition, DN animals diagnosed with RCC showed increased expression of GLUT2 and c-met, when compared to controls and DN animals without tumors.

Discussion

In conclusion, the disordered calcium metabolism, especially disturbed TRPV5 mediated Ca²⁺ signal, may have been related to the development of RCC in DN rats. Further studies related to the detailed mechanism are still needed.

A Phase I Study on the Pharmacokinetics and Pharmacodynamics of DJT1116PG, a Novel Selective Inhibitor of Sodium-glucose Cotransporter Type 2, in Healthy Individuals at Steady State

PURPOSE

DJT1116PG, which selectively inhibits renal glucose reabsorption by inhibiting sodium-glucose cotransporter type 2, was developed as an insulin-independent treatment for type 2 diabetes mellitus. This Phase I trial evaluated the pharmacokinetic and pharmacodynamic properties of DJT1116PG at steady state in healthy Chinese individuals.

METHODS

This was a multiple ascending dose study of DJT1116PG (20, 50, and 100 mg once daily for 7 days) that included 36 healthy individuals.

FINDINGS

There were no serious adverse events or deaths in these studies, and no adverse event led to study discontinuation. Oral DJT1116PG was rapidly absorbed with a T_max of 0.75-1.5 h and a t_½ of 12-16.2 h. Systemic exposure (C_max and AUC) of DJT1116PG and its inactive metabolites (T1444, T1454, and T1830) increased in a dose-dependent manner. Urinary glucose excretion (UGE) plateaued at 50 mg of DJT1116PG in a previous single ascending dose study and on day 1 of this study. UGE plateaued at 20 mg of DJT1116PG on day 7 of this study. Serum glucose parameters were similar in individuals who received DJT1116PG or placebo.

IMPLICATIONS

DJT1116PG was well tolerated in healthy Chinese individuals. At steady state, UGE plateaued at 20 mg of DJT1116PG in these individuals. These findings will inform the selection of doses for further early-stage clinical trials of DJT1116PG. Chinese Drug Trial Identifier: CTR20160986.

Pharmacokinetics and pharmacodynamics of rongliflozin, a novel selective inhibitor of sodium-glucose co-transporter-2, in people with type 2 diabetes mellitus

AIMS

To evaluate the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics of rongliflozin in a cohort of healthy Chinese people and people with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

We examined the effects of a single ascending dose (SAD) of rongliflozin (10-200 mg) in combination with food (20 mg) in 50 healthy people, and a multiple ascending dose (MAD) of rongliflozin (10-50 mg once daily for 12 days) in 36 people with T2DM.

RESULTS

No serious adverse events (AEs) or discontinuations as a result of AEs (related to rongliflozin) occurred in either study. In healthy participants and those with T2DM, rongliflozin was rapidly absorbed, with a time to maximum plasma concentration of 0.63 to 1.75 hours. Systemic exposure (maximum observed serum concentration and area under the curve) to rongliflozin and its inactive major metabolites (T1444, T1454 and T1830) increased in proportion to dose. In the SAD and MAD studies, there was a dose-related increase in urinary glucose excretion (UGE) ranging from 10 to 50 mg rongliflozin. This increase in UGE was associated with dose-related decreases in serum glucose values in people with T2DM in the MAD group. In the SAD group, UGE plateaued at 50 to 200 mg.

CONCLUSIONS

Rongliflozin was well tolerated in all participants. The PK and PD measurements obtained for rongliflozin demonstrate a dose-response relationship when the drug is administered at doses ranging from 10 to 50 mg in healthy people and in people with T2DM.

Effect of Insulin on Proximal Tubules Handling of Glucose: A Systematic Review

Renal proximal tubules reabsorb glucose from the glomerular filtrate and release it back into the circulation. Modulation of glomerular filtration and renal glucose disposal are some of the insulin actions, but little is known about a possible insulin effect on tubular glucose reabsorption. This review is aimed at synthesizing the current knowledge about insulin action on glucose handling by proximal tubules. Method. A systematic article selection from Medline (PubMed) and Embase between 2008 and 2019. 180 selected articles were clustered into topics (renal insulin handling, proximal tubule glucose transport, renal gluconeogenesis, and renal insulin resistance). Summary of Results. Insulin upregulates its renal uptake and degradation, and there is probably a renal site-specific insulin action and resistance; studies in diabetic animal models suggest that insulin increases renal SGLT2 protein content; in vivo human studies on glucose transport are few, and results of glucose transporter protein and mRNA contents are conflicting in human kidney biopsies; maximum renal glucose reabsorptive capacity is higher in diabetic patients than in healthy subjects; glucose stimulates SGLT1, SGLT2, and GLUT2 in renal cell cultures while insulin raises SGLT2 protein availability and activity and seems to directly inhibit the SGLT1 activity despite it activating this transporter indirectly. Besides, insulin regulates SGLT2 inhibitor bioavailability, inhibits renal gluconeogenesis, and interferes with Na⁺K⁺ATPase activity impacting on glucose transport. Conclusion. Available data points to an important insulin participation in renal glucose handling, including tubular glucose transport, but human studies with reproducible and comparable method are still needed.

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.

Acute saccharin infusion has no effect on renal glucose handling in normal rats in vivo

Artificial sweeteners are extensively used by the food industry to replace sugar in food and beverages and are widely considered to be a healthy alternative. However, recent data suggest that artificial sweeteners may impact intestinal glucose absorption and that they might lead to glucose intolerance. Moreover, chronic consumption of artificial sweeteners has also been linked to detrimental changes in renal function. Using an in vivo approach, our study aimed to determine if short-term infusion of the artificial sweetener saccharin can alter renal function and renal glucose absorption. We show that saccharin infusion does not induce any major change in GFR or urine flow rate at either the whole kidney or single nephron level, suggesting that any reported change in renal function with artificial sweeteners must depend on chronic consumption. As expected for a nondiabetic animal, glucose excretion was low; however, saccharin infusion caused a small, but significant, decrease in fractional glucose excretion. In contrast to the whole kidney data, our micropuncture results did not show any significant difference in fractional glucose reabsorption in either the proximal or distal tubules, indicating that saccharin does not influence renal glucose handling in vivo under euglycemic conditions. In keeping with this finding, protein levels of the renal glucose transporters SGLT1 and SGLT2 were also unchanged. In addition, saccharin infusion in rats undergoing a glucose tolerance test failed to induce a robust change in renal glucose excretion or renal glucose transporter expression. In conclusion, our results demonstrate that saccharin does not induce acute physiologically relevant changes in renal function or renal glucose handling.

Combining streptozotocin and unilateral nephrectomy is an effective method for inducing experimental diabetic nephropathy in the 'resistant' C57Bl/6J mouse strain

Diabetic nephropathy (DN) is the leading cause of chronic kidney disease. Animal models are essential tools for designing new strategies to prevent DN. C57Bl/6 (B6) mice are widely used for transgenic mouse models, but are relatively resistant to DN. This study aims to identify the most effective method to induce DN in a type 1 (T1D) and a type 2 diabetes (T2D) model in B6 mice. For T1D-induced DN, mice were fed a control diet, and randomised to streptozotocin (STZ) alone, STZ+unilateral nephrectomy (UNx), or vehicle/sham. For T2D-induced DN, mice were fed a western (high fat) diet, and randomised to either STZ alone, STZ+UNx, UNx alone, or vehicle/sham. Mice subjected to a control diet with STZ +UNx developed albuminuria, glomerular lesions, thickening of the glomerular basement membrane, and tubular injury. Mice on control diet and STZ developed only mild renal lesions. Furthermore, kidneys from mice on a western diet were hardly affected by diabetes, UNx or the combination. We conclude that STZ combined with UNx is the most effective model to induce T1D-induced DN in B6 mice. In our hands, combining western diet and STZ treatment with or without UNx did not result in a T2D-induced DN model in B6 mice.

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

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

Modulation of Renal GLUT2 by the Cannabinoid-1 Receptor: Implications for the Treatment of Diabetic Nephropathy

Altered glucose reabsorption via the facilitative glucose transporter 2 (GLUT2) during diabetes may lead to renal proximal tubule cell (RPTC) injury, inflammation, and interstitial fibrosis. These pathologies are also triggered by activating the cannabinoid-1 receptor (CB₁R), which contributes to the development of diabetic nephropathy (DN). However, the link between CB₁R and GLUT2 remains to be determined. Here, we show that chronic peripheral CB₁R blockade or genetically inactivating CB₁Rs in the RPTCs ameliorated diabetes-induced renal structural and functional changes, kidney inflammation, and tubulointerstitial fibrosis in mice. Inhibition of CB₁R also downregulated GLUT2 expression, affected the dynamic translocation of GLUT2 to the brush border membrane of RPTCs, and reduced glucose reabsorption. Thus, targeting peripheral CB₁R or inhibiting GLUT2 dynamics in RPTCs has the potential to treat and ameliorate DN. These findings may support the rationale for the clinical testing of peripherally restricted CB₁R antagonists or the development of novel renal-specific GLUT2 inhibitors against DN.

The roles of sodium-glucose cotransporter 2 inhibitors in preventing kidney injury in diabetes

Diabetic nephropathy (DN) is the leading cause of end stage renal disease (ESRD) worldwide. The early effective treatment of high plasma glucose could delay or prevent the onset of DN. Sodium-glucose cotransporter 2 (SGLT2) inhibitors are new target treatments for ameliorating high plasma glucose and help to maintain glucose homeostasis in diabetic patients. Reduced renal glucose reabsorption by SGLT2 inhibition seems to have high potential to improve glycemic control in diabetes mellitus (DM) not only through glucose lowering but also through glucose-independent effects such as blood pressure-lowering and direct renal effects in diabetes. Of note, the important events in the pathogenesis of glucose-induced renal injury and DN including oxidative stress, inflammation, fibrosis and apoptosis conditions have shown to be ameliorate after the treatment with SGLT2 inhibitors. Interestingly, SGLT2 inhibitors have been reported to reduce albuminuria in DM via an activation of renal tubuloglomerular feedback by increased macula densa sodium and chloride delivery, leading to afferent vasoconstriction and attenuated diabetes-induced renal hyperfiltration. These effects also help to conserve glomerular integrity. Thus, the treatment of diabetes mellitus using SGLT2 inhibitors could be one of the effective approach for the management of diabetic-associated kidney disease like DN. This review summarizes the up to date information and discusses the bidirectional relationship between the SGLT2 inhibitor treatments and the renal functions that are available from both basic research and clinical reports. The details of renal outcomes of SGLT2 inhibitors in DN are also provide in this review.

Postprandial adjustments in renal phosphate excretion do not involve a gut-derived phosphaturic factor

NEW FINDINGS

What is the central question of this study? Does a previously hypothesized signalling mechanism, believed to detect postprandial increases in intestinal phosphate and that can stimulate the kidneys to rapidly excrete phosphate, operate under physiological conditions? What is the main finding and its importance? Contrary to earlier reports, rapid signalling between the small intestine and kidney mediated by a gut-derived phosphaturic factor in response to a physiological intestinal phosphate load is not supported by the present findings; moreover, hyperphosphataemia and increased parathyroid hormone concentrations are likely to be the underlying factors responsible for the phosphaturia following a supraphysiological intestinal phosphate load. To date, the role of the small intestine in the regulation of postprandial phosphate homeostasis has remained unclear and controversial. Previous studies have proposed the presence of a gut-derived phosphaturic factor that acts independently of changes in plasma phosphate concentration or parathyroid hormone (PTH) concentration; however, these early studies used duodenal luminal phosphate concentrations in the molar range, and therefore, the physiological relevance of this is uncertain. In the present study, we used both in vivo and in vitro approaches to investigate the presence of this putative 'intestinal phosphatonin'. Instillation of 1.3 m phosphate into the duodenum rapidly induced phosphaturia, but in contrast to previous reports, this was associated with significant hyperphosphataemia and elevated PTH concentration; however, there was not the expected decrease in abundance of the renal sodium-phosphate cotransporter NaPi-IIa. Instillation of a physiological (10 mm) phosphate load had no effect on plasma phosphate concentration, PTH concentration or phosphate excretion. Moreover, phosphate uptake by opossum kidney cells was unaffected after incubation with serosal fluid collected from intestinal segments perfused with different concentrations of phosphate. Taken together, these findings do not support the concept of a gut-derived phosphaturic factor that can mediate rapid signalling between the gut and kidney, leading to increased urinary phosphate excretion, as part of normal phosphate homeostasis.