Hypoxia-inducible factor-1α is the therapeutic target of the SGLT2 inhibitor for diabetic nephropathy

Fufang Zhenzhu Tiaozhi (FTZ) capsule ameliorates diabetic kidney disease in mice via inhibiting the SGLT2/glycolysis pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Fufang Zhenzhu Tiaozhi (FTZ) capsule is a hospital preparation of a patented traditional Chinese medicine compound. FTZ has been clinically used for nearly 13 years in the treatment of diabetes and glycolipid metabolic diseases. With the significant benefits of SGLT2 inhibitor in patients with diabetic kidney disease (DKD), it provides a research avenue to explore the mechanism of FTZ in treating this disease based on glycolysis pathway.

AIM OF THE STUDY

To explore the pharmacological characteristics of FTZ in DKD mice and its impact on the glycolysis pathway.

MATERIALS AND METHODS

We induced a DKD model in C57BL/6 mice by injection of streptozotocin (STZ) combined with long-term high-fat diet. We administered three doses of FTZ for 12 weeks of treatment. Kidney function, blood lipid levels, glucose tolerance, and key glycolytic enzymes were evaluated. Renal pathological changes were observed using HE, MASSON, and PAS staining. The potential targets of the active ingredients of FTZ in the glycolysis pathway were predicted using network pharmacology and molecular docking. Validation was performed using immunohistochemistry and Western blotting.

RESULTS

FTZ effectively reduces blood glucose, total cholesterol, triglyceride, low density lipoprotein cholesterol, 24 h proteinuria, serum creatinine, blood urea nitrogen, and increases urinary glucose levels. Glucose tolerance and renal pathological changes were significantly improved by FTZ treatment. Pinusolidic acid, a component of FTZ, shows good binding affinity with three active pockets of SGLT2. WB and immunohistochemistry revealed that FTZ significantly inhibits the expression of SGLT2 and its glycolytic related proteins (GLUT2/PKM2/HK2). Hexokinase, pyruvate kinase, and lactate dehydrogenase in the kidney were also significantly inhibited by FTZ in a dose-dependent manner.

CONCLUSION

FTZ may alleviate the progression of DKD by inhibiting the activation of the SGLT2/glycolytic pathway. Our study provides new insights into the clinical application of FTZ in DKD.

Is There a Role for SGLT2 Inhibitors in Patients with End-Stage Kidney Disease?

PURPOSE OF REVIEW

Chronic kidney disease and end-stage kidney disease (ESKD) are well-established risk factors for cardiovascular disease (CVD), the leading cause of mortality in the dialysis population. Conventional therapies, such as statins, blood pressure control, and renin-angiotensin-aldosterone system blockade, have inadequately addressed this cardiovascular risk, highlighting the unmet need for effective treatment strategies. Sodium-glucose transporter 2 (SGLT2) inhibitors have demonstrated significant renal and cardiovascular benefits among patients with type 2 diabetes, heart failure, or CKD at risk of progression. Unfortunately, efficacy data in dialysis patients is lacking as ESKD was an exclusion criterion for all major clinical trials of SGLT2 inhibitors. This review explores the potential of SGLT2 inhibitors in improving cardiovascular outcomes among patients with ESKD, focusing on their direct cardiac effects.

RECENT FINDINGS

Recent clinical and preclinical studies have shown promising data for the application of SGLT2 inhibitors to the dialysis population. SGLT2 inhibitors may provide cardiovascular benefits to dialysis patients, not only indirectly by preserving the remaining kidney function and improving anemia but also directly by lowering intracellular sodium and calcium levels, reducing inflammation, regulating autophagy, and alleviating oxidative stress and endoplasmic reticulum stress within cardiomyocytes and endothelial cells. This review examines the current clinical evidence and experimental data supporting the use of SGLT2 inhibitors, discusses its potential safety concerns, and outlines ongoing clinical trials in the dialysis population. Further research is needed to evaluate the safety and effectiveness of SGLT2 inhibitor use among patients with ESKD.

Exploring potential targets for natural product therapy of DN: the role of SUMOylation

Diabetic nephropathy (DN) is a common and serious micro-vascular complication of diabetes and a leading cause of end-stage renal disease globally. This disease primarily affects middle-aged and elderly individuals, especially those with a diabetes history of over 10 years and poor long-term blood glucose control. Small ubiquitin-related modifiers (SUMOs) are a group of reversible post-translational modifications of proteins that are widely expressed in eukaryotes. SUMO proteins intervene in the progression of DN by modulating various signaling cascades, such as Nrf2-mediated oxidative stress, NF-κB, TGF-β, and MAPK pathways. Recent advancements indicate that natural products regulating SUMOylation hold promise as targets for intervening in DN. In a previous article published in 2022, we reviewed the mechanisms by which SUMOylation intervenes in renal fibrosis and presented a summary of some natural products with therapeutic potential. Therefore, this paper will focus on DN. The aim of this review is to elucidate the mechanism of action of SUMOylation in DN and related natural products with therapeutic potential, thereby summarising the targets and candidate natural products for the treatment of DN through the modulation of SUMOylation, such as ginkgolic acid, ginkgolide B, resveratrol, astragaloside IV, etc., and highlighting that natural product-mediated modulation of SUMOylation is a potential therapeutic strategy for the treatment of DN as a potential therapeutic strategy.

Exploring the mechanism of action of Chinese medicine in regulating liver fibrosis based on the alteration of glucose metabolic pathways

In recent years, metabolic reprogramming in liver fibrosis has become a research hotspot in the field of liver fibrosis at home and abroad. Liver fibrosis is a pathological change caused by chronic liver injury from a variety of causes. Liver fibrosis is a common pathological feature of many chronic liver diseases such as chronic hepatitis B, non-alcoholic steatohepatitis, and autoimmune hepatitis, as well as the pathogenesis of the disease. The development of chronic liver disease into cirrhosis must go through the pathological process of liver fibrosis, in which hepatic stellate cells (HSC) play an important role. Following liver injury, HSC are activated and transdifferentiated into scar-forming myofibroblasts, which drive the trauma healing response and which rely on the deposition of collagen-rich extracellular matrix to maintain tissue integrity. This reaction will continue without strict control, which will lead to excessive accumulation of matrix and liver fibrosis. The mechanisms and clinical studies of liver fibrosis have been the focus of research in liver diseases. In recent years, several studies have revealed the mechanism of HSC metabolic reprogramming and the impact of this process on liver fibrosis, in which glucose metabolic reprogramming plays an important role in the activation of HSC, and it mainly meets the energy demand of HSC activation by upregulating glycolysis. Glycolysis is the process by which one molecule of glucose is broken down into two molecules of pyruvate and produces energy and lactate under anaerobic conditions. Various factors have been found to be involved in regulating the glycolytic process of HSC, including glucose transport, intracellular processing of glucose, exosome secretion, and lactate production, etc. Inhibition of the glycolytic process of HSC can be an effective strategy against liver fibrosis. Currently, the combined action of multiple targets and links of Chinese medicine such as turmeric, comfrey, rhubarb and scutellaria baicalensis against the mechanism of liver fibrosis can effectively improve or even reverse liver fibrosis. This paper summarizes that turmeric extract curcumin, comfrey extract comfreyin, rhubarb, Subtle yang yu yin granules, Scutellaria baicalensis extract oroxylin A and cardamom extract cardamomin affect liver fibrosis by regulating gluconeogenic reprogramming. Therefore, studying the mechanism of action of TCM in regulating liver fibrosis through reprogramming of glucose metabolism is promising to explore new methods and approaches for Chinese Medicine modernization research.

How can inhibition of glucose and sodium transport in the early proximal tubule protect the cardiorenal system?

What mechanisms can link the inhibition of sodium-glucose cotransporter 2 (SGLT2) in the early proximal tubule to kidney and heart protection in patients with and without type 2 diabetes? Due to physical and functional coupling of SGLT2 to other sodium and metabolite transporters in the early proximal tubule (including NHE3, URAT1), inhibitors of SGLT2 (SGLT2i) reduce reabsorption not only of glucose, inducing osmotic diuresis, but of other metabolites plus of a larger amount of sodium than expected based on SGLT2 inhibition alone, thereby reducing volume retention, hypertension and hyperuricemia. Metabolic adaptations to SGLT2i include a fasting-like response, with enhanced lipolysis and formation of ketone bodies that serve as additional fuel for kidneys and heart. Making use of the physiology of tubulo-glomerular communication, SGLT2i functionally lower glomerular capillary pressure and filtration rate, thereby reducing physical stress on the glomerular filtration barrier, tubular exposure to albumin and nephrotoxic compounds, and the oxygen demand for reabsorbing the filtered load. Together with reduced gluco-toxicity in the early proximal tubule and better distribution of transport work along the nephron, SGLT2i can preserve tubular integrity and transport function and, thereby, glomerular filtration rate in the long-term. By shifting transport downstream, SGLT2i may simulate systemic hypoxia at the oxygen sensors in the deep cortex/outer medulla, which stimulates erythropoiesis and, together with osmotic diuresis, enhances hematocrit and thereby improves oxygen delivery to all organs. The described SGLT2-dependent effects may be complemented by off-target effects of SGLT2i on the heart itself and on the microbiome formation of cardiovascular-effective uremic toxins.

Early use of SGLT2 inhibitors reduces the progression of diabetic kidney disease: a retrospective cohort study

OBJECTIVE

To evaluate the potential of sodium-glucose cotransporter 2 (SGLT2) inhibitors in preventing the progression of diabetic kidney disease and to provide guidance for clinical practice to improve renal health management strategies for diabetic patients.

METHODS

A retrospective analysis was conducted on 178 patients with diabetic kidney disease admitted to Baoji High Tech Hospital from March 2023 to March 2024. Of these, 88 patients who received early treatment with the SGLT2 inhibitor dapagliflozin were included in the early SGLT2-i group, while 90 patients receiving later treatment with SGLT2 inhibitor dapagliflozin were included in the late SGLT2-i group. Clinical data, overall effectiveness, adverse reactions, blood glucose, renal function, lipid levels, and inflammatory markers were compared between the two groups.

RESULTS

Prior to treatment, there were no differences in blood glucose indicators between the two groups (all P > 0.05). Following treatment, both groups showed reductions in 2-hour postprandial blood glucose (2hPG), fasting plasma glucose (FPG), and glycosylated hemoglobin (HbA1c), with the early SGLT2-i group demonstrating significantly lower values compared to the late SGLT2-i group (all P < 0.05). Similarly, there were no differences in renal function indicators between the two groups before treatment (all P > 0.05). However, following treatment, the early SGLT2-i group showed more noticeable improvements compared to the late SGLT2-i group (P < 0.05). Inflammatory markers and lipid levels followed similar patterns. The overall effectiveness of the early SGLT2-i group was higher than that of the late SGLT2-i group (92.05% vs. 78.89%, P < 0.05), while the incidence of adverse reactions did not differ statistically between the two groups (6.82% vs. 10.00%, P > 0.05).

CONCLUSION

Early use of SGLT2 inhibitors in diabetic kidney disease patients effectively controls blood glucose and lipid levels, improves renal function, reduces inflammatory responses, and exhibits a low incidence of adverse reactions. This demonstrates high safety and an important role in delaying disease progression. Therefore, it is worth considering clinical promotion and use for this patient population.

How do SGLT2 inhibitors protect the kidney? A mediation analysis of the EMPA-REG OUTCOME trial

INTRODUCTION

Mechanisms underlying kidney benefits with sodium-glucose cotransporter-2 (SGLT2) inhibition in heart failure and/or type 2 diabetes (T2D) with established cardiovascular disease are currently unclear.

METHODS

We evaluated post hoc the factors mediating the effect of empagliflozin on a composite kidney outcome (first sustained estimated glomerular filtration rate ≥40% reduction from baseline, initiation of renal replacement therapy or death due to kidney disease) in EMPA-REG OUTCOME (Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients). Variables, calculated as change from baseline or updated mean, were evaluated as time-dependent covariates and using a landmark approach (at Week 12) in Cox regression analyses. In multivariable analyses, variables with the greatest mediating effect were added using a step-up procedure.

RESULTS

In univariable time-dependent updated mean covariate analyses, the strongest mediator was hematocrit (99.5% mediation). Hemoglobin, uric acid and urine albumin-to-creatinine ratio mediated 79.4%, 33.2% and 31.0%, respectively. Multivariable analyses were not performed due to the very strong mediation effect of hematocrit. In univariable Week 12 landmark change from baseline analyses, the strongest mediators included hematocrit (40.7%), glycated hemoglobin (28.3%), systolic blood pressure (16.8%) and free fatty acids (16.5%), which yielded a combined mediation of 78.9% in multivariable analysis.

CONCLUSIONS

Changes in hematocrit and hemoglobin were the strongest mediators of empagliflozin's kidney benefits in EMPA-REG OUTCOME participants with T2D and cardiovascular disease.

mTOR and SGLT-2 Inhibitors: Their Synergistic Effect on Age-Related Processes

The aging process contributes significantly to the onset of chronic diseases, which are the primary causes of global mortality, morbidity, and healthcare costs. Numerous studies have shown that the removal of senescent cells from tissues extends lifespan and reduces the occurrence of age-related diseases. Consequently, there is growing momentum in the development of drugs targeting these cells. Among them, mTOR and SGLT-2 inhibitors have garnered attention due to their diverse effects: mTOR inhibitors regulate cellular growth, metabolism, and immune responses, while SGLT-2 inhibitors regulate glucose reabsorption in the kidneys, resulting in various beneficial metabolic effects. Importantly, these drugs may act synergistically by influencing senescence processes and pathways. Although direct studies on the combined effects of mTOR inhibition and SGLT-2 inhibition on age-related processes are limited, this review aims to highlight the potential synergistic benefits of these drugs in targeting senescence.

Unraveling the Triad: Hypoxia, Oxidative Stress and Inflammation in Neurodegenerative Disorders

The mammalian brain's complete dependence on oxygen for ATP production makes it highly susceptible to hypoxia, at high altitudes or in clinical scenarios including anemia or pulmonary disease. Hypoxia plays a crucial role in the development of various brain disorders, such as Alzheimer's, Parkinson's, and other age-related neurodegenerative diseases. On the other hand, a decrease in environmental oxygen levels, such as prolonged stays at high elevations, may have beneficial impacts on the process of ageing and the likelihood of death. Additionally, the utilization of controlled hypoxia exposure could potentially serve as a therapeutic approach for age-related brain diseases. Recent findings indicate that the involvement of HIF-1α and the NLRP3 inflammasome is of significant importance in the development of Alzheimer's disease. HIF-1α serves as a pivotal controller of various cellular reactions to oxygen deprivation, exerting influence on a multitude of physiological mechanisms such as energy metabolism and inflammatory responses. The NLRP3 plays a crucial role in the innate immune system by coordinating the initiation of inflammatory reactions through the assembly of the inflammasome complex. This review examines the information pertaining to the contrasting effects of hypoxia on the brain, highlighting both its positive and deleterious effects and molecular pathways that are involved in mediating these different effects. This study explores potential strategies for therapeutic intervention that focus on restoring cellular balance and reducing neuroinflammation, which are critical aspects in addressing this severe neurodegenerative condition and addresses crucial inquiries that warrant further future investigations.

Renoprotective effect of a novel combination of 6-gingerol and metformin in high-fat diet/streptozotocin-induced diabetic nephropathy in rats via targeting miRNA-146a, miRNA-223, TLR4/TRAF6/NLRP3 inflammasome pathway and HIF-1α

BACKGROUND

MiRNA-146a and miRNA-223 are key epigenetic regulators of toll-like receptor 4 (TLR4)/tumor necrosis factor-receptor-associated factor 6 (TRAF6)/NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome pathway, which is involved in diabetic nephropathy (DN) pathogenesis. The currently available oral anti-diabetic treatments have been insufficient to halt DN development and progression. Therefore, this work aimed to assess the renoprotective effect of the natural compound 6-gingerol (GR) either alone or in combination with metformin (MET) in high-fat diet/streptozotocin-induced DN in rats. The proposed molecular mechanisms were also investigated.

METHODS

Oral gavage of 6-gingerol (100 mg/kg) and metformin (300 mg/kg) were administered to rats daily for eight weeks. MiRNA-146a, miRNA-223, TLR4, TRAF6, nuclear factor-kappa B (NF-κB) (p65), NLRP3, caspase-1, and hypoxia-inducible factor-1 alpha (HIF-1α) mRNA expressions were measured using real-time PCR. ELISA was used to measure TLR4, TRAF6, NLRP3, caspase-1, tumor necrosis factor-alpha (TNF-α), and interleukin-1-beta (IL-1β) renal tissue levels. Renal tissue histopathology and immunohistochemical examination of fibronectin and NF-κB (p65) were performed.

RESULTS

6-Gingerol treatment significantly reduced kidney tissue damage and fibrosis. 6-Gingerol up-regulated miRNA-146a and miRNA-223 and reduced TLR4, TRAF6, NF-κB (p65), NLRP3, caspase-1, TNF-α, IL-1β, HIF-1α and fibronectin renal expressions. 6-Gingerol improved lipid profile and renal functions, attenuated renal hypertrophy, increased reduced glutathione, and decreased blood glucose and malondialdehyde levels. 6-Gingerol and metformin combination showed superior renoprotective effects than either alone.

CONCLUSION

6-Gingerol demonstrated a key protective role in DN by induction of miRNA-146a and miRNA-223 expression and inhibition of TLR4/TRAF6/NLRP3 inflammasome signaling. 6-Gingerol, a safe, affordable, and abundant natural compound, holds promise for use as an adjuvant therapy with metformin in diabetic patients to attenuate renal damage and stop the progression of DN.

The potential anti-arrhythmic effect of SGLT2 inhibitors

Sodium-glucose cotransporter type 2 inhibitors (SGLT2i) were initially recommended as oral anti-diabetic drugs to treat type 2 diabetes (T2D), by inhibiting SGLT2 in proximal tubule and reduce renal reabsorption of sodium and glucose. While many clinical trials demonstrated the tremendous potential of SGLT2i for cardiovascular diseases. 2022 AHA/ACC/HFSA guideline first emphasized that SGLT2i were the only drug class that can cover the entire management of heart failure (HF) from prevention to treatment. Subsequently, the antiarrhythmic properties of SGLT2i have also attracted attention. Although there are currently no prospective studies specifically on the anti-arrhythmic effects of SGLT2i. We provide clues from clinical and fundamental researches to identify its antiarrhythmic effects, reviewing the evidences and mechanism for the SGLT2i antiarrhythmic effects and establishing a novel paradigm involving intracellular sodium, metabolism and autophagy to investigate the potential mechanisms of SGLT2i in mitigating arrhythmias.

Risks of carpal tunnel syndrome and carpal tunnel release surgery in users of sodium-glucose cotransporter 2 inhibitors and glucagon-like peptide-1 receptor agonists: A target trial emulation study

AIM

Preclinical studies have shown that sodium-glucose cotransporter 2 inhibitors (SGLT2is) have a neuroprotective effect. This study compared the risks of carpal tunnel syndrome and carpal tunnel release surgery between new users of SGLT2is and new users of glucagon-like peptide-1 receptor agonists (GLP-1RAs).

METHODS

A retrospective new-user active comparator cohort study with a target trial design was conducted by using the TriNetX platform. Patients with type 2 diabetes mellitus prescribed SGLT2is or GLP-1RAs were identified. Covariates were balanced using propensity score matching to form 2 homogenous treatment groups. Outcomes were the risk of carpal tunnel syndrome and the risk of carpal tunnel release surgery. Hazard ratios (HRs) with 95 % confidence intervals (CIs) were calculated using the TriNetX platform.

RESULTS

The crude cohort included 86,188 and 100,244 patients in the SGLT2is group and GLP-1RAs group, respectively. After matching, each group included 65,464 patients. The SGLT2is group had an average age of 59.6 years, and 46 % were women. The GLP-1RAs group had an average age of 59.5 years, and 45.9 % were women. The incidences of carpal tunnel syndrome (HR: 0.928; 95 % CI: 0.869 to 0.991) and carpal tunnel release surgery (HR: 0.840; 95 % CI: 0.726 to 0.971) were significantly lower in the SGLT2is group than in the GLP-1RAs group.

CONCLUSION

In patients with type 2 diabetes mellitus, SGLT2is seem to decrease the risk of carpal tunnel syndrome and the need for carpal tunnel release surgery. Prospective studies are required to confirm our results.

Changes in serum levels of liver-related parameters, uric acid, and hemoglobin in patients with type 2 diabetes mellitus under treatment with tofogliflozin-a post-hoc analysis of the UTOPIA study

Aims/Introduction

The aim of the study was to evaluate the effects of tofogliflozin, a selective sodium-glucose cotransporter 2 inhibitor, on circulating levels of hepatic enzymes, uric acid and hemoglobin levels in patients with type 2 diabetes mellitus (T2DM).

Materials and methods

We evaluated longitudinal changes in circulating aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (γ-GTP), uric acid, and hemoglobin levels in tofogliflozin (n = 169) and conventional treatment groups (n = 170) using data obtained from the UTOPIA trial, a randomized prospective study conducted to evaluate the efficacy of tofogliflozin in preventing atherosclerosis.

Results

Within 104 weeks, tofogliflozin treatment, but not conventional treatment, significantly reduced AST, ALT, and γ-GTP levels. This reduction was significantly greater in the tofogliflozin group than in the conventional group. Stratified analysis showed that, in patients with obesity (defined as body mass index (BMI) ≥ 25.0 kg/m2), significant differences were observed in AST, ALT, and γ-GTP changes from baseline to 104 weeks between treatment groups. However, in patients without obesity, there were no significant differences in AST and γ-GTP changes from baseline to 104 weeks between treatment groups. Multivariable regression analysis showed that changes in BMI and HbA1c levels were independently associated with changes in AST, ALT, and γ-GTP levels. The reduction of uric acid and the increase of hemoglobin from baseline to 104 weeks were significantly greater in the tofogliflozin group than in the conventional group.

Conclusions

The beneficial effects of tofogliflozin on circulating levels of hepatic enzymes, uric acid, and Hb lasted for 2 years in patients with T2DM.

Clinical trial registration

UMIN000017607 (https://www.umin.ac.jp/icdr/index.html).

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-024-00693-x.

The role of hypoxia in chronic kidney disease: a nuanced perspective

PURPOSE OF REVIEW

This review critically examines the role of hypoxia in chronic kidney disease (CKD). While traditionally viewed as detrimental, recent insights suggest a more nuanced understanding of hypoxia's role during renal disease.

RECENT FINDINGS

Emerging evidence challenges the traditional view that hypoxia is universally harmful in CKD context. We review here the recent evidence about hypoxia and HIF activation in CKD. We also discuss the effect of hypoxia on the renal tissue, and the relative inhibition of different HIF isoforms. Recent advancements in therapies, such as HIF prolyl hydroxylase inhibitors (HIF-PHIs) and sodium-glucose cotransporter 2 (SGLT2) inhibitors seem to target the HIF pathway. These drugs impact anemia associated with CKDbut also renoprotection, hinting at a more complex interplay between hypoxia, HIF activation, and renal health.

SUMMARY

A certain level of hypoxia and specific HIF pathway activation, especially HIF-α, can be beneficial in CKD progression. Therapeutic strategies targeting HIF stabilization, such as with HIF-PHIs and SGLT2 inhibitors, offer promising avenues for enhancing renal protection. Future investigations should aim at better understanding the precise effects on HIF pathway and optimize their clinical application to improve outcomes for CKD patients.

The Renoprotective Mechanisms of Sodium-Glucose Cotransporter-2 Inhibitors (SGLT2i)-A Narrative Review

Chronic kidney disease (CKD) is a noncommunicable condition that has become a major healthcare burden across the globe, often underdiagnosed and associated with low awareness. The main cause that leads to the development of renal impairment is diabetes mellitus and, in contrast to other chronic complications such as retinopathy or neuropathy, it has been suggested that intensive glycemic control is not sufficient in preventing the development of diabetic kidney disease. Nevertheless, a novel class of antidiabetic agents, the sodium-glucose cotransporter-2 inhibitors (SGLT2i), have shown multiple renoprotective properties that range from metabolic and hemodynamic to direct renal effects, with a major impact on reducing the risk of occurrence and progression of CKD. Thus, this review aims to summarize current knowledge regarding the renoprotective mechanisms of SGLT2i and to offer a new perspective on this innovative class of antihyperglycemic drugs with proven pleiotropic beneficial effects that, after decades of no significant progress in the prevention and in delaying the decline of renal function, start a new era in the management of patients with CKD.

Empagliflozin, a sodium-glucose cotransporter inhibitor enhancing mitochondrial action and cardioprotection in metabolic syndrome

Metabolic syndrome (MetS) has a large clinical population nowadays, usually due to excessive energy intake and lack of exercise. During MetS, excess nutrients stress the mitochondria, resulting in relative hypoxia in tissues and organs, even when blood supply is not interrupted or reduced, making mitochondrial dysfunction a central pathogenesis of cardiovascular disease in the MetS. Sodium-glucose cotransporter 2 inhibitors were designed as a hyperglycemic drug that acts on the renal tubules to block sugar reabsorption in primary urine. Recently they have been shown to have anti-inflammatory and other protective effects on cardiomyocytes in MetS, and have also been recommended in the latest heart failure guidelines as a routine therapy. Among these inhibitors, empagliflozin shows better clinical promise due to less influence from glomerular filtration rate. This review focuses on the mitochondrial mechanisms of empagliflozin, which underlie the anti-inflammatory and recover cellular functions in MetS cardiomyocytes, including stabilizing calcium concentration, mediating metabolic reprogramming, maintaining homeostasis of mitochondrial quantity and quality, stable mitochondrial DNA copy number, and repairing damaged mitochondrial DNA.

Effect of continuous positive airway pressure treatment on Th17/Treg imbalance in patients with obstructive sleep apnea and a preliminary study on its mechanism

BACKGROUND

Obstructive sleep apnea (OSA) can be considered a chronic inflammatory disease that impacts all bodily systems, including the immune system. This study aims to assess the Th17/Treg pattern in patients with OSA and the effect of continuous positive airway pressure (CPAP) treatment.

METHODS

OSA patients and healthy controls were recruited. OSA patients recommended for CPAP treatment were followed up for three months. Flow cytometry was employed to determine the proportion of Th17 and Treg cells. Real-time quantitative polymerase chain reaction (PCR) and western blotting were utilized to detect the mRNA and protein levels of receptor-related orphan receptor γt (RORγt) and forkhead/winged helix transcription factor (Foxp3), respectively, in peripheral blood mononuclear cells (PBMCs). Enzyme-linked immunosorbent assay (ELISA) was performed to measure the serum levels of interleukin-17 (IL-17), IL-6, transforming growth factor-β1 (TGF-β1), and hypoxia-induced factor-1α (HIF-1α).

RESULTS

A total of 56 OSA patients and 40 healthy controls were recruited. The proportion of Th17 cells, Th17/Treg ratio, mRNA and protein levels of RORγt, and serum IL-17, IL-6, and HIF-1α levels were higher in OSA patients. Conversely, the proportion of Treg cells, mRNA and protein levels of Foxp3, and serum TGF-β1 levels were decreased in OSA patients. The proportion of Th17 and Treg cells in OSA can be predicted by the apnea hypopnea index (AHI), IL-6, TGF-β1 and, HIF-1α. 30 moderate-to-severe OSA patients were adherent to three-month CPAP treatment, with improved Th17/Treg imbalance, IL-17, IL-6, TGF-β1, and HIF-1α levels compared to pre-treatment values.

CONCLUSION

There was a Th17/Treg imbalance in OSA patients. The prediction of Th17 and Treg cell proportions in OSA can be facilitated by AHI, as well as serum IL-6, TGF-β1, and HIF-1α levels. Furthermore, CPAP treatment can potentially improve the Th17/Treg imbalance and reduce proinflammatory cytokines in OSA patients.

Pharmacological targets of SGLT2 inhibitors on IgA nephropathy and membranous nephropathy: a mendelian randomization study

Introduction

Emerging research suggests that sodium-glucose cotransporter 2 (SGLT2) inhibitors may play a pivotal role in the treatment of primary glomerular diseases. This study was aimed to investigate potential pharmacological targets connecting SGLT2 inhibitors with IgA nephropathy (IgAN) and membranous nephropathy (MN).

Methods

A univariate Mendelian randomization (MR) analysis was conducted using publicly available genome-wide association studies (GWAS) datasets. Co-localization analysis was used to identify potential connections between target genes and IgAN and MN. Then, Comparative Toxicogenomics Database (CTD) was employed to predict diseases associated with these target genes and SGLT2 inhibitors (canagliflozin, dapagliflozin, and empagliflozin). Subsequently, phenotypic scan analyses were applied to explore the causal relationships between the predicted diseases and target genes. Finally, we analyzed the immune signaling pathways involving pharmacological target genes using the Kyoto encyclopedia of genes and genomes (KEGG).

Results

The results of MR analysis revealed that eight drug targets were causally linked to the occurrence of IgAN, while 14 drug targets were linked to MN. In the case of IgAN, LCN2 and AGER emerged as co-localized genes related to the pharmacological agent of dapagliflozin and the occurrence of IgAN. LCN2 was identified as a risk factor, while AGER was exhibited a protective role. KEGG analysis revealed that LCN2 is involved in the interleukin (IL)-17 immune signaling pathway, while AGER is associated with the neutrophil extracellular traps (NETs) signaling immune pathway. No positive co-localization results of the target genes were observed between two other SGLT2 inhibitors (canagliflozin and empagliflozin) and the occurrence of IgAN, nor between the three SGLT2 inhibitors and the occurrence of MN.

Conclusion

Our study provided evidence supporting a causal relationship between specific SGLT2 inhibitors and IgAN. Furthermore, we found that dapagliflozin may act on IgAN through the genes LCN2 and AGER.

SERPINE1: Role in Cholangiocarcinoma Progression and a Therapeutic Target in the Desmoplastic Microenvironment

A heterogenous population of inflammatory elements, other immune and nonimmune cells and cancer-associated fibroblasts (CAFs) are evident in solid malignancies where they coexist with the growing tumor mass. In highly desmoplastic malignancies, CAFs are the prominent mesenchymal cell type in the tumor microenvironment (TME), where their presence and abundance signal a poor prognosis. CAFs play a major role in the progression of various cancers by remodeling the supporting stroma into a dense, fibrotic matrix while secreting factors that promote the maintenance of cancer stem-like characteristics, tumor cell survival, aggressive growth and metastasis and reduced sensitivity to chemotherapeutics. Tumors with high stromal fibrotic signatures are more likely to be associated with drug resistance and eventual relapse. Identifying the molecular underpinnings for such multidirectional crosstalk among the various normal and neoplastic cell types in the TME may provide new targets and novel opportunities for therapeutic intervention. This review highlights recent concepts regarding the complexity of CAF biology in cholangiocarcinoma, a highly desmoplastic cancer. The discussion focuses on CAF heterogeneity, functionality in drug resistance, contributions to a progressively fibrotic tumor stroma, the involved signaling pathways and the participating genes.

SGLT2 Inhibitors and Kidney Protection: Mechanisms Beyond Tubuloglomerular Feedback

Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the risk for kidney failure and are a key component of guideline-directed therapy for CKD. While SGLT2 inhibitors' ability to activate tubuloglomerular feedback and reduce hyperfiltration-mediated kidney injury is considered to be the central mechanism for kidney protection, recent data from experimental studies raise questions on the primacy of this mechanism. This review examines SGLT2 inhibitors' role in tubuloglomerular feedback and summarizes emerging evidence on following of SGLT2 inhibitors' other putative mechanisms for kidney protection: optimization of kidney's energy substrate utilization and delivery, regulation of autophagy and maintenance of cellular homeostasis, attenuation of sympathetic hyperactivity, and improvement in vascular health and microvascular function. It is imperative to examine the effect of SGLT2 inhibition on these different physiologic processes to help our understanding of mechanisms underpinning kidney protection with this important class of drugs.

Systemic and organ-specific anti-inflammatory effects of sodium-glucose cotransporter-2 inhibitors

Inflammation plays an essential role and is a common feature in the pathogenesis of many chronic diseases. The exact mechanisms through which sodium-glucose cotransporter-2 (SGLT2) inhibitors achieve their much-acclaimed clinical benefits largely remain unknown. In this review, we detail the systemic and tissue- or organ-specific anti-inflammatory effects of SGLT2 inhibitors using evidence from animal and human studies. We discuss the potential pathways through which SGLT2 inhibitors exert their anti-inflammatory effects, including oxidative stress, mitochondrial, and inflammasome pathways. Finally, we highlight the need for further investigation of the extent of the contribution of the anti-inflammatory effects of SGLT2 inhibition to improvements in cardiometabolic and renal outcomes in clinical studies.

Risk of rotator cuff tear and rotator cuff repair surgery comparison between sodium-glucose cotransporter 2 inhibitors and glucagon like peptide-1 receptor agonists: A real-world study

AIM

Theoretically, sodium-glucose cotransporter 2 inhibitors (SGLT2is) reduce the risk of rotator cuff tear through an anti-inflammatory mechanism. To clarify this association, in this study, we compared SGLT2is users and glucagon-like peptide-1 receptor agonists (GLP-1RAs) users in terms of the risk of rotator cuff tear and the risk of receiving rotator cuff repair surgery.

METHODS

A retrospective cohort analysis was conducted using data from the TriNetX platform. A target trial design was adopted to identify patients with type 2 diabetes mellitus who started receiving SGLT2is or GLP-1RAs. Propensity score matching was used to form two homogeneous groups. The study outcomes were the risk of rotator cuff tear and the risk of receiving rotator cuff repair surgery. Hazard ratios (HRs) with 95 % confidence intervals (CIs) were calculated within the TriNetX platform.

RESULTS

Initially, 351,800 SGLT2is users and 387,616 GLP-1RAs users were identified. After propensity score matching, each group comprised 274,026 patients. The mean age was 59.5 years in both groups; the proportions of women in the SGLT2is and GLP-1RAs groups were 46.9 % and 46.7 %, respectively. Compared with the GLP-1RAs group, the SGLT2is group had significantly reduced risks of rotator cuff tear (HR 0.812 [0.761;0.867]) and rotator cuff repair surgery (HR 0.900 [0.815;0.994]).

CONCLUSION

SGLT2is appear to reduce the risk of rotator cuff tear and the risk of receiving rotator cuff repair surgery in patients with type 2 diabetes mellitus. Further prospective studies are needed to validate our findings.

Pathogenesis of diabetic complications: Exploring hypoxic niche formation and HIF-1α activation

Hypoxia is a common feature of diabetic tissues, which highly correlates to the progression of diabetes. The formation of hypoxic context is induced by disrupted oxygen homeostasis that is predominantly driven by vascular remodeling in diabetes. While different types of vascular impairments have been reported, the specific features and underlying mechanisms are yet to be fully understood. Under hypoxic condition, cells upregulate hypoxia-inducible factor-1α (HIF-1α), an oxygen sensor that coordinates oxygen concentration and cell metabolism under hypoxic conditions. However, diabetic context exploits this machinery for pathogenic functions. Although HIF-1α protects cells from diabetic insult in multiple tissues, it also jeopardizes cell function in the retina. To gain a deeper understanding of hypoxia in diabetic complications, we focus on the formation of tissue hypoxia and the outcomes of HIF-1α dysregulation under diabetic context. Hopefully, this review can provide a better understanding on hypoxia biology in diabetes.

Effect of SGLT2 inhibitors on anemia and their possible clinical implications

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have demonstrated cardiovascular and renal benefits in patients with type 2 diabetes mellitus, heart failure, or chronic kidney disease. Since the first studies with these drugs, an initial increase in hemoglobin/hematocrit levels was observed, which was attributed to an increase in hemoconcentration associated with its diuretic effect, although it was early appearent that these drugs increased erythropoietin levels and erythropoiesis, and improved iron metabolism. Mediation studies found that the increase in hemoglobin was strongly associated with the cardiorenal benefits of these drugs. In this review, we discuss the mechanisms for improving erythropoiesis and the implication of the increase in hemoglobin on the cardiorenal prognostic benefit of these drugs.

The Perspective of Using Flow Cytometry for Unpuzzling Hypoxia-Inducible Factors Signalling

Hypoxia-inducible factors (HIFs) are transcription factors that are responsible for adapting to the changes in oxygen levels in the cellular environment. HIF activity determines the expression of cellular proteins that control the development and physiology of the cells and pathophysiology of a disease. Understanding the role of specific HIF (HIF-1-3) in cellular function is essential for development of the HIF-targeted therapies. In this review, we have discussed the use of flow cytometry in analysing HIF function in cells. Proper understanding of HIF-signalling will help to design pharmacological interventions HIF-mediated therapy. We have discussed the role of HIF-signalling in various diseases such as cancer, renal and liver diseases, ulcerative colitis, arthritis, diabetes and diabetic complications, psoriasis, and wound healing. We have also discussed protocols that help to decipher the role of HIFs in these diseases that would eventually help to design promising therapies.

Mechanism of hypoxia-induced exosome circ_0051799 regulating the progression of lung adenocarcinoma

This study attempted to investigate the effect of circ_0051799 on the immune microenvironment of lung adenocarcinoma (LUAD) and the relationship between circ_0051799 and exosomes. The number and morphology of exosomes were verified by nanoparticle tracking, transmission electron microscopy and western blotting. CCK8, EdU, Transwell and flow cytometry were used to verify the regulatory role of exosomes and circ_0051799 on tumor progression. Dual luciferase reporting and RNA immunoprecipitation were used to verify the targeted regulatory relationship between circ_0051799, miR-214-3p and IGF2BP3. WB was used to verify the role of the JAK/STAT pathway in circ_0051799 regulation. Ectopic tumor grafts and in situ models were used to validate in vivo their role in regulating LUAD progression. Hypoxic environment could alter but does not alter its shape. Exosomes can participate in the regulation of macrophage polarization by circ_0051799. In vitro and in vivo assays had shown that circ_0051799 could affect the proliferation and metastasis of LUAD through targeting miR-214-3p mediated IGF2BP3 regulated JAK/STAT pathway. This study found that hypoxia can affect LUAD process by promoting the regulation of macrophage polarization by exosome circ_0051799.

SGLT2 inhibitors, intrarenal hypoxia and the diabetic kidney: insights into pathophysiological concepts and current evidence

Approximately 20-40% of all diabetic patients experience chronic kidney disease, which is related to higher mortality (cardiovascular and all-cause). A large body of evidence suggests that renal hypoxia is one of the main forces that drives diabetic kidney disease, both in its early and advanced stages. It promotes inflammation, generation of intrarenal collagen, capillary rarefaction and eventually accumulation of extracellular matrix that destroys normal renal architecture. SGLT2 inhibitors are unquestionably a practice-changing drug class and a valuable weapon for patients with type 2 diabetes and chronic kidney disease. They have achieved several beneficial kidney effects after targeting multiple and interrelated signaling pathways, including renal hypoxia, independent of their antihyperglycemic activities. This manuscript discusses the pathophysiological concepts that underly their possible effects on modulating renal hypoxia. It also comprehensively investigates both preclinical and clinical studies that explored the possible role of SGLT2 inhibitors in this setting, so as to achieve long-term renoprotective benefits.

Oxidative Stress Induced by Lipotoxicity and Renal Hypoxia in Diabetic Kidney Disease and Possible Therapeutic Interventions: Targeting the Lipid Metabolism and Hypoxia

Oxidative stress, a hallmark pathophysiological feature in diabetic kidney disease (DKD), arises from the intricate interplay between pro-oxidants and anti-oxidants. While hyperglycemia has been well established as a key contributor, lipotoxicity emerges as a significant instigator of oxidative stress. Lipotoxicity encompasses the accumulation of lipid intermediates, culminating in cellular dysfunction and cell death. However, the mechanisms underlying lipotoxic kidney injury in DKD still require further investigation. The key role of cell metabolism in the maintenance of cell viability and integrity in the kidney is of paramount importance to maintain proper renal function. Recently, dysfunction in energy metabolism, resulting from an imbalance in oxygen levels in the diabetic condition, may be the primary pathophysiologic pathway driving DKD. Therefore, we aim to shed light on the pivotal role of oxidative stress related to lipotoxicity and renal hypoxia in the initiation and progression of DKD. Multifaceted mechanisms underlying lipotoxicity, including oxidative stress with mitochondrial dysfunction, endoplasmic reticulum stress activated by the unfolded protein response pathway, pro-inflammation, and impaired autophagy, are delineated here. Also, we explore potential therapeutic interventions for DKD, targeting lipotoxicity- and hypoxia-induced oxidative stress. These interventions focus on ameliorating the molecular pathways of lipid accumulation within the kidney and enhancing renal metabolism in the face of lipid overload or ameliorating subsequent oxidative stress. This review highlights the significance of lipotoxicity, renal hypoxia-induced oxidative stress, and its potential for therapeutic intervention in DKD.

Effects of Dapagliflozin on Myocardial Gene Expression in BTBR Mice with Type 2 Diabetes

BACKGROUND

Dapagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, is approved for the treatment of type 2 diabetes, heart failure, and chronic kidney disease. DAPA-HF and DELIVER trial results demonstrate that the cardiovascular protective effect of dapagliflozin extends to non-diabetic patients. Hence, the mechanism-of-action may extend beyond glucose-lowering and is not completely elucidated. We have previously shown that dapagliflozin reduces cardiac hypertrophy, inflammation, fibrosis, and apoptosis and increases ejection fraction in BTBR mice with type 2 diabetes.

METHODS

We conducted a follow-up RNA-sequencing study on the heart tissue of these animals and performed differential expression and Ingenuity Pathway analysis. Selected markers were confirmed by RT-PCR and Western blot.

RESULTS

SGLT2 had negligible expression in heart tissue. Dapagliflozin improved cardiac metabolism by decreasing glycolysis and pyruvate utilization enzymes, induced antioxidant enzymes, and decreased expression of hypoxia markers. Expression of inflammation, apoptosis, and hypertrophy pathways was decreased. These observations corresponded to the effects of dapagliflozin in the clinical trials.

DPP-4i versus SGLT2i as modulators of PHD3/HIF-2α pathway in the diabetic kidney

RATIONALE

Renal hypoxia is one of the currently highlighted pathophysiologic mechanisms of diabetic nephropathy (DN). Both hypoxia-inducible factor-1α (HIF-1α) and HIF-2α are major regulators of renal adaptive responses to hypoxia.

OBJECTIVES

This study aims to compare the effects of vildagliptin (a dipeptidyl peptidase-IV inhibitor, DPP-4i) and empagliflozin (a sodium-glucose cotransporter 2 inhibitor, SGLT2i) on the differential expression of renal HIF-1α/2α. Tissue expression of prolylhydroxylase 3 (PHD3), a key regulator of HIF-2α stability, was also highlighted in a diabetic nephropathy rat model. Type 1 diabetes mellitus was induced and diabetic rats were treated with either Vildagliptin or Empagliflozin (10 mg/kg/d each) for 12 weeks. Improvements in the kidney functional and histopathological parameters were addressed and correlated to changes in the renal expression of HIF-1α/2α, and PHD3. Urinary KIM-1 concentration was tested as a correlate to HIF pathway changes.

FINDINGS

Both vildagliptin- and empagliflozin-treated groups exhibited significant improvement in the functional, pathological, and ultra-structural renal changes induced by chronic diabetes. Compared to the untreated group, renal gene expression of HIF-1α was decreased while that of HIF-2α was increased in both treated groups, with significantly greater effects observed with SGLT2i. Renal PHD3 immune-reactivity was also decreased by both drugs, again with better efficacy for the SGLT2i. Importantly, improvements in the diabetic kidney biochemical and structural biomarkers were significantly correlated to PHD3 reductions and HIF-2α increments.

CONCLUSIONS

Both DPP-4i and SGLT2i could delay the progression of DN through their differential modulating effects on the PHD3/ HIF-2α pathway with significantly better efficacy for SGLT2i.

Mechanisms of benefits of sodium-glucose cotransporter 2 inhibitors in heart failure with preserved ejection fraction

For decades, heart failure with preserved ejection fraction (HFpEF) proved an elusive entity to treat. Sodium-glucose cotransporter 2 (SGLT2) inhibitors have recently been shown to reduce the composite of heart failure hospitalization or cardiovascular death in patients with HFpEF in the landmark DELIVER and EMPEROR-Preserved trials. While improvements in blood sugar, blood pressure, and attenuation of kidney disease progression all may play some role, preclinical and translational research have identified additional mechanisms of these agents. The SGLT2 inhibitors have intriguingly been shown to induce a nutrient-deprivation and hypoxic-like transcriptional paradigm, with increased ketosis, erythropoietin, and autophagic flux in addition to altering iron homeostasis, which may contribute to improved cardiac energetics and function. These agents also reduce epicardial adipose tissue and alter adipokine signalling, which may play a role in the reductions in inflammation and oxidative stress observed with SGLT2 inhibition. Emerging evidence also indicates that these drugs impact cardiomyocyte ionic homeostasis although whether this is through indirect mechanisms or via direct, off-target effects on other ion channels has yet to be clearly characterized. Finally, SGLT2 inhibitors have been shown to reduce myofilament stiffness as well as extracellular matrix remodelling/fibrosis in the heart, improving diastolic function. The SGLT2 inhibitors have established themselves as robust, disease-modifying therapies and as recent trial results are incorporated into clinical guidelines, will likely become foundational in the therapy of HFpEF.

Identification of ferroptosis-related genes in type 2 diabetes mellitus based on machine learning

BACKGROUND

Type 2 diabetes mellitus (T2DM), which has a high incidence and several harmful consequences, poses a severe danger to human health. Research on the function of ferroptosis in T2DM is increasing. This study uses bioinformatics techniques identify new diagnostic T2DM biomarkers associated with ferroptosis.

METHODS

To identify ferroptosis-related genes (FRGs) that are differentially expressed between T2DM patients and healthy individuals, we first obtained T2DM sequencing data and FRGs from the Gene Expression Omnibus (GEO) database and FerrDb database. Then, drug-gene interaction networks and competitive endogenous RNA (ceRNA) networks linked to the marker genes were built after marker genes were filtered by two machine learning algorithms (LASSO and SVM-RFE algorithms). Finally, to confirm the expression of marker genes, the GSE76895 dataset was utilized. The protein and RNA expression of some marker genes in T2DM and nondiabetic tissues was also examined by Western blotting, immunohistochemistry (IHC), immunofluorescence (IF) and quantitative real-time PCR (qRT-PCR).

RESULTS

We obtained 58 differentially expressed genes (DEGs) associated with ferroptosis. GO and KEGG enrichment analyses showed that these DEGs were significantly enriched in hypoxia and ferroptosis. Subsequently, eight marker genes (SCD, CD44, HIF1A, BCAT2, MTF1, HILPDA, NR1D2, and MYCN) were screened by LASSO and SVM-RFE machine learning algorithms, and a model was constructed based on these eight genes. This model also has high diagnostic power. In addition, based on these eight genes, we obtained 48 drugs and constructed a complex ceRNA network map. Finally, Western blotting, IHC, IF, and qRT-PCR results of clinical samples further confirmed the results of public databases.

CONCLUSIONS

The diagnosis and aetiology of T2DM can be greatly aided by eight FRGs, providing novel therapeutic avenues.

Hypoxia and renal fibrosis

Renal fibrosis is the final stage of most progressive kidney diseases. Chronic kidney disease (CKD) is associated with high comorbidity and mortality. Thus, preventing fibrosis and thereby preserving kidney function increases the quality of life and prolongs the survival of patients with CKD. Many processes such as inflammation or metabolic stress modulate the progression of kidney fibrosis. Hypoxia has also been implicated in the pathogenesis of renal fibrosis, and oxygen sensing in the kidney is of outstanding importance for the body. The dysregulation of oxygen sensing in the diseased kidney is best exemplified by the loss of stimulation of erythropoietin production from interstitial cells in the fibrotic kidney despite anemia. Furthermore, hypoxia is present in acute or chronic kidney diseases and may affect all cell types present in the kidney including tubular and glomerular cells as well as resident immune cells. Pro- and antifibrotic effects of the transcription factors hypoxia-inducible factors 1 and 2 have been described in a plethora of animal models of acute and chronic kidney diseases, but recent advances in sequencing technologies now allow for novel and deeper insights into the role of hypoxia and its cell type-specific effects on the progression of renal fibrosis, especially in humans. Here, we review existing literature on how hypoxia impacts the development and progression of renal fibrosis.

A Role for Sodium-Glucose Cotransporter 2 Inhibitors in the Treatment of Chronic Kidney Disease: A Mini Review

BACKGROUND

Sodium-glucose cotransport protein 2 (SGLT2) inhibitors, a new type of glucose-lowering drug, have been well proved in several clinical studies for their glucose-lowering and nephroprotective effects, and the nephroprotective effects include both indirect effects of metabolic improvement and direct effects, independent of glucose-lowering effects.

SUMMARY

In patients with diabetic kidney disease (DKD), several studies have demonstrated the potential nephroprotective mechanisms of SGLT2 inhibitors, and evidence of nephroprotective mechanisms in the non-DKD population is accumulating. Although the nephroprotective mechanism of SGLT2 inhibitors has not been fully elucidated, several laboratory studies have illustrated the mechanism underlying the effects of SGLT2 inhibitors at various aspects.

KEY MESSAGES

The purpose of this article is to review the mechanism of nephroprotective effect of SGLT2 inhibitors and to look forward to promising research in the future.

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

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

LncRNA SNHG1 knockdown inhibits hyperglycemia induced ferroptosis via miR-16-5p/ACSL4 axis to alleviate diabetic nephropathy

BACKGROUND

Hyperglycemia accelerates the development of diabetic nephropathy (DN) by inducing renal tubular injury. Nevertheless, the mechanism has not been elaborated fully. Here, the pathogenesis of DN was investigated to seek novel treatment strategies.

METHODS

A model of diabetic nephropathy was established in vivo, the levels of blood glucose, urine albumin creatinine ratio (ACR), creatinine, blood urea nitrogen (BUN), malondialdehyde (MDA), glutathione (GSH), and iron were measured. The expression levels were detected by qRT-PCR and Western blotting. H&E, Masson, and PAS staining were used to assess kidney tissue injury. The mitochondria morphology was observed by transmission electron microscopy (TEM). The molecular interaction was analyzed using a dual luciferase reporter assay.

RESULTS

SNHG1 and ACSL4 were increased in kidney tissues of DN mice, but miR-16-5p was decreased. Ferrostatin-1 treatment or SNHG1 knockdown inhibited ferroptosis in high glucose (HG)-treated HK-2 cells and in db/db mice. Subsequently, miR-16-5p was confirmed to be a target for SNHG1, and directly targeted to ACSL4. Overexpression of ACSL4 greatly reversed the protective roles of SNHG1 knockdown in HG-induced ferroptosis of HK-2 cells.

CONCLUSIONS

SNHG1 knockdown inhibited ferroptosis via the miR-16-5p/ACSL4 axis to alleviate diabetic nephropathy, which provided some new insights for the novel treatment of diabetic nephropathy.

Tubular injury in diabetic kidney disease: molecular mechanisms and potential therapeutic perspectives

Diabetic kidney disease (DKD) is a chronic complication of diabetes and the leading cause of end-stage renal disease (ESRD) worldwide. Currently, there are limited therapeutic drugs available for DKD. While previous research has primarily focused on glomerular injury, recent studies have increasingly emphasized the role of renal tubular injury in the pathogenesis of DKD. Various factors, including hyperglycemia, lipid accumulation, oxidative stress, hypoxia, RAAS, ER stress, inflammation, EMT and programmed cell death, have been shown to induce renal tubular injury and contribute to the progression of DKD. Additionally, traditional hypoglycemic drugs, anti-inflammation therapies, anti-senescence therapies, mineralocorticoid receptor antagonists, and stem cell therapies have demonstrated their potential to alleviate renal tubular injury in DKD. This review will provide insights into the latest research on the mechanisms and treatments of renal tubular injury in DKD.

Managing Anemia: Point of Convergence for Heart Failure and Chronic Kidney Disease?

The pathologic triangle formed by chronic heart failure (HF), chronic kidney disease (CKD), and anemia carries high morbidity and mortality rates and decreases quality of life. Anemia represents a common condition in patients with advanced HF and CKD, with a total prevalence in cardiorenal syndrome (CRS) ranging from 5% to 55%. Searching for a pragmatic approach for these patients with guided and disease-specific recommendations beyond just targeted hemoglobin therapeutic behavior represents the core of research for ongoing clinical trials. It is well known that the prevalence of anemia increases with the advancement of CKD and HF. The physiopathological mechanisms of anemia, such as the reduction of endogenous erythropoietin and the decrease in oxygen transport, are leading to tissue hypoxia, peripheral vasodilation, stimulating neurohormonal activity, and maintenance of the progressive renal and cardiac dysfunction. Given the challenges with the treatment options for patients with cardiorenal anemia syndrome (CRSA), new therapeutic agents such as hypoxia-inducible factor-prolyl hydroxylase domain inhibitors (HIF-PH) or hepcidin antagonists are emerging in the light of recent research. This review summarizes the potential therapeutic tools for anemia therapy in the cardiorenal population.

Mechanistic and Clinical Comparison of the Erythropoietic Effects of SGLT2 Inhibitors and Prolyl Hydroxylase Inhibitors in Patients with Chronic Kidney Disease and Renal Anemia

Renal anemia is treated with erythropoiesis-stimulating agents (ESAs), even though epoetin alfa and darbepoetin increase the risk of cardiovascular death and thromboembolic events, including stroke. Hypoxia-inducible factor prolyl hydroxylase domain (HIF-PHD) inhibitors have been developed as an alternative to ESAs, producing comparable increases in hemoglobin. However, in advanced chronic kidney disease, HIF-PHD inhibitors can increase the risk of cardiovascular death, heart failure, and thrombotic events to a greater extent than that with ESAs, indicating that there is a compelling need for safer alternatives. Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the risk of major cardiovascular events, and they increase hemoglobin, an effect that is related to an increase in erythropoietin and an expansion in red blood cell mass. SGLT2 inhibitors increase hemoglobin by ≈0.6-0.7 g/dL, resulting in the alleviation of anemia in many patients. The magnitude of this effect is comparable to that seen with low-to-medium doses of HIF-PHD inhibitors, and it is apparent even in advanced chronic kidney disease. Interestingly, HIF-PHD inhibitors act by interfering with the prolyl hydroxylases that degrade both HIF-1α and HIF-2α, thus enhancing both isoforms. However, HIF-2α is the physiological stimulus to the production of erythropoietin, and upregulation of HIF-1α may be an unnecessary ancillary property of HIF-PHD inhibitors, which may have adverse cardiac and vascular consequences. In contrast, SGLT2 inhibitors act to selectively increase HIF-2α, while downregulating HIF-1α, a distinctive profile that may contribute to their cardiorenal benefits. Intriguingly, for both HIF-PHD and SGLT2 inhibitors, the liver is likely to be an important site of increased erythropoietin production, recapitulating the fetal phenotype. These observations suggest that the use of SGLT2 inhibitors should be seriously evaluated as a therapeutic approach to treat renal anemia, yielding less cardiovascular risk than other therapeutic options.

Canagliflozin alleviates high glucose-induced peritoneal fibrosis via HIF-1α inhibition

The cardioprotective effects of sodium-glucose cotransporter type 2 (SGLT2) inhibitors have been demonstrated in many studies. However, their benefits for end-stage kidney disease patients, particularly those on peritoneal dialysis, remain unclear. SGLT2 inhibition has shown peritoneal protective effects in some studies, but the mechanisms are still unknown. Herein, we investigated the peritoneal protective mechanisms of Canagliflozin in vitro by simulating hypoxia with CoCl₂ in human peritoneal mesothelial cells (HPMCs) and rats by intraperitoneal injection of 4.25% peritoneal dialysate simulating chronic high glucose exposure. CoCl₂ hypoxic intervention significantly increased HIF-1α abundance in HPMCs, activated TGF-β/p-Smad3 signaling, and promoted the production of fibrotic proteins (Fibronectin, COL1A2, and α-SMA). Meanwhile, Canagliflozin significantly improved the hypoxia of HPMCs, decreased HIF-1α abundance, inhibited TGF-β/p-Smad3 signaling, and decreased the expression of fibrotic proteins. Five-week intraperitoneal injection of 4.25% peritoneal dialysate remarkably increased peritoneal HIF-1α/TGF-β/p-Smad3 signaling and promoted peritoneal fibrosis and peritoneal thickening. At the same time, Canagliflozin significantly inhibited the HIF-1α/TGF-β/p-Smad3 signaling, prevented peritoneal fibrosis and peritoneal thickening, and improved peritoneal transportation and ultrafiltration. High glucose peritoneal dialysate increased the expression of peritoneal GLUT1, GLUT3 and SGLT2, all of which were inhibited by Canagliflozin. In conclusion, we showed that Canagliflozin could improve peritoneal fibrosis and function by ameliorating peritoneal hypoxia and inhibiting the HIF-1α/TGF-β/p-Smad3 signaling pathway, providing theoretical support for the clinical use of SGLT2 inhibitors in patients on peritoneal dialysis.

Responses to Hypoxia: How Fructose Metabolism and Hypoxia-Inducible Factor-1a Pathways Converge in Health and Disease

PURPOSE OF REVIEW

Oxygen is critical for the high output of energy (adenosine triphosphate) generated by oxidative phosphorylation in the mitochondria, and when oxygen delivery is impaired due to systemic hypoxia, impaired or reduced delivery of red blood cells, or from local ischemia, survival processes are activated.

RECENT FINDINGS

One major mechanism is the activation of hypoxia-inducible factors (HIFs) that act to reduce oxygen needs by blocking mitochondrial function and stimulating glucose uptake and glycolysis while also stimulating red blood cell production and local angiogenesis. Recently, endogenous fructose production with uric acid generation has also been shown to occur in hypoxic and ischemic tissues where it also appears to drive the same functions, and indeed, there is evidence that many of hypoxia-inducible factors effects may be mediated by the stimulation of fructose production and metabolism. Unfortunately, while being acutely protective, these same systems in overdrive lead to chronic inflammation and disease and may also be involved in the development of metabolic syndrome and related disease. The benefit of SGLT2 inhibitors may act in part by reducing the delivery of glucose with the stimulation of fructose formation, thereby allowing a conversion from the glycolytic metabolism to one involving mitochondrial metabolism. The use of hypoxia-inducible factor stabilizers is expected to aid the treatment of anemia but, in the long-term, could potentially lead to worsening cardiovascular and metabolic outcomes. We suggest more studies are needed on the use of these agents.

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

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

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.

Renal outcomes with sodium-glucose cotransporters 2 inhibitors

Diabetic nephropathy (DN) is one of the most serious complications of diabetes. Therefore, delaying and preventing the progression of DN becomes an important goal in the clinical treatment of type 2 diabetes mellitus. Recent studies confirm that sodium-glucose cotransporters 2 inhibitors (SGLT2is) have been regarded as effective glucose-lowering drugs with renal protective effect. In this review, we summarize in detail the present knowledge of the effects of SGLT2is on renal outcomes by analyzing the experimental data in preclinical study, the effects of SGLT2is on estimated glomerular flitration rates (eGFRs) and urinary albumin-creatinine ratios (UACRs) from clinical trials and observational studies, and renal events (such as renal death or renal failure requiring renal replacement therapy) in some large prospective cardiovaslucar outcomes trials. The underlying mechanisms for renoprotective activity of SGLT2is have been demondtrated in multiple diabetic and nondiabetic animal models including kidney-specific effects and secondary kidney effects related to amelioration in blood glucose and blood pressure. In conclusion, these promising results show that SGLT2is act beneficially in terms of the kidney for diabetic patients.

Exploring the mechanisms underlying the therapeutic effect of the drug pair Rhubarb-Coptis in diabetic nephropathy using network pharmacology and molecular docking analysis

Background

To use network pharmacology to explore the mechanism of the drug pair Rhubarb-Coptis in the treatment of diabetic nephropathy (DN).

Methods

The Traditional Chinese Medicine Systems Pharmacology (TCMSP) database was used to screen active ingredients of drug pair Rhubarb-Coptis. Targets were obtained using the TCMSP and SwissTargetPrediction databases. DN disease targets were extracted from the Online Mendelian Inheritance in Man (OMIM), GeneCards, and Therapeutic Target database (TTD) databases. A "drug-compound-target" network and protein-protein interaction (PPI) network were constructed and analyzed through the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database and Cytoscape software. Gene Ontology (GO) functional and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed in the Database for Annotation, Visualization, and Integrated Discovery (DAVID) database. Molecular docking was performed using AutoDock Vina and PyMOL software.

Results

A total of 30 active components and 609 targets of Rhubarb-Coptis were screened out, and 98 common targets of DN and Rhubarb-Coptis were obtained. Quercetin, berberine, epiruberine, epautin, and moupinamide were the main active components in the treatment of DN. The STAT3, CTNNB1, PIK3R1, PIK3CA, and TP53 genes were identified as the potential 5 key targets. The GO enrichment analysis showed that these 5 key targets mainly involved in inflammation, oxidative stress, and apoptosis. KEGG enrichment analysis showed that the pathways were mainly enriched in the AGE-RAGE and HIF-1 signaling pathways. Molecular docking revealed that the 5 key targets could combine well with their corresponding active compounds.

Conclusions

This study expounds the therapeutic effect of Rhubarb-Coptis on DN from a holistic perspective, and provides a valuable basis for clinical application and academic research.

Hypoxia-inducible factor signaling in vascular calcification in chronic kidney disease patients

Chronic kidney disease (CKD) affects approximately 15% of the adult population in high-income countries and is associated with significant comorbidities, including increased vascular calcifications which is associated with a higher risk for cardiovascular events. Even though the underlying pathophysiology is unclear, hypoxia-inducible factor (HIF) signaling appears to play a central role in inflammation, angiogenesis, fibrosis, cellular proliferation, apoptosis and vascular calcifications which is influenced by multiple variables such as iron deficiency anemia, serum phosphorus and calcium levels, fibroblast growth factor-23 (FGF-23) and Klotho. Along with the growing understanding of the pathology, potential therapeutic alternatives have emerged including HIF stabilizers and SGLT-2 inhibitors. The aim of this review is to discuss the role of HIF signaling in the pathophysiology of vascular calcification in CKD patients and to identify potential therapeutic approaches.

Mutual Regulation between Redox and Hypoxia-Inducible Factors in Cardiovascular and Renal Complications of Diabetes

Oxidative stress and hypoxia-inducible factors (HIFs) have been implicated in the pathogenesis of diabetic cardiovascular and renal diseases. Reactive oxygen species (ROS) mediate physiological and pathophysiological processes, being involved in the modulation of cell signaling, differentiation, and survival, but also in cyto- and genotoxic damage. As master regulators of glycolytic metabolism and oxygen homeostasis, HIFs have been largely studied for their role in cell survival in hypoxic conditions. However, in addition to hypoxia, other stimuli can regulate HIFs stability and transcriptional activity, even in normoxic conditions. Among these, a regulatory role of ROS and their byproducts on HIFs, particularly the HIF-1α isoform, has received growing attention in recent years. On the other hand, HIF-1α and HIF-2α exert mutually antagonistic effects on oxidative damage. In diabetes, redox-mediated HIF-1α deregulation contributes to the onset and progression of cardiovascular and renal complications, and recent findings suggest that deranged HIF signaling induced by hyperglycemia and other cellular stressors associated with metabolic disorders may cause mitochondrial dysfunction, oxidative stress, and inflammation. Understanding the mechanisms of mutual regulation between HIFs and redox factors and the specific contribution of the two main isoforms of HIF-α is fundamental to identify new therapeutic targets for vascular complications of diabetes.

Renoprotective Effects of SGLT2 Inhibitors

SGLT2 inhibitors can protect the kidneys of patients with and without type 2 diabetes from failing. This includes blood glucose dependent and independent mechanisms. SGLT2 inhibitors lower glomerular pressure and filtration, thereby reducing the physical stress on the filtration barrier and the oxygen demand for tubular reabsorption. This improves cortical oxygenation, which, together with lesser tubular glucotoxicity and improved mitochondrial function and autophagy, can reduce proinflammatory and profibrotic signaling and preserve tubular function and GFR in long term. By shifting transport downstream, SGLT2 inhibitors may mimic systemic hypoxia and stimulate erythropoiesis, which improves oxygen delivery to the kidney and other organs.

Hypoxia-Inducible Factors and Diabetic Kidney Disease—How Deep Can We Go?

Diabetes is one of the leading causes of chronic kidney disease (CKD), and multiple underlying mechanisms involved in pathogenesis of diabetic nephropathy (DN) have been described. Although various treatments and diagnosis applications are available, DN remains a clinical and economic burden, considering that about 40% of type 2 diabetes patients will develop nephropathy. In the past years, some research found that hypoxia response and hypoxia-inducible factors (HIFs) play critical roles in the pathogenesis of DN. Hypoxia-inducible factors (HIFs) HIF-1, HIF-2, and HIF-3 are the main mediators of metabolic responses to the state of hypoxia, which seems to be the one of the earliest events in the occurrence and progression of diabetic kidney disease (DKD). The abnormal activity of HIFs seems to be of crucial importance in the pathogenesis of diseases, including nephropathies. Studies using transcriptome analysis confirmed by metabolome analysis revealed that HIF stabilizers (HIF-prolyl hydroxylase inhibitors) are novel therapeutic agents used to treat anemia in CKD patients that not only increase endogenous erythropoietin production, but also could act by counteracting the metabolic alterations in incipient diabetic kidney disease and relieve oxidative stress in the renal tissue. In this review, we present the newest data regarding hypoxia response and HIF involvement in the pathogenesis of diabetic nephropathy and new therapeutic insights, starting from improving kidney oxygen homeostasis.

Metabolic reprogramming: A novel therapeutic target in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the most common microvascular complications of diabetes mellitus. However, the pathological mechanisms contributing to DKD are multifactorial and poorly understood. Diabetes is characterized by metabolic disorders that can bring about a series of changes in energy metabolism. As the most energy-consuming organs secondary only to the heart, the kidneys must maintain energy homeostasis. Aberrations in energy metabolism can lead to cellular dysfunction or even death. Metabolic reprogramming, a shift from mitochondrial oxidative phosphorylation to glycolysis and its side branches, is thought to play a critical role in the development and progression of DKD. This review focuses on the current knowledge about metabolic reprogramming and the role it plays in DKD development. The underlying etiologies, pathological damages in the involved cells, and potential molecular regulators of metabolic alterations are also discussed. Understanding the role of metabolic reprogramming in DKD may provide novel therapeutic approaches to delay its progression to end-stage renal disease.