Mechanisms Leading to Differential Hypoxia-Inducible Factor Signaling in the Diabetic Kidney: Modulation by SGLT2 Inhibitors and Hypoxia Mimetics

SGLT2 Inhibitors: A New Therapeutical Strategy to Improve Clinical Outcomes in Patients with Chronic Kidney Diseases

The purpose of this manuscript is to review the effects of sodium-glucose cotransport protein 2 inhibitors (SGLT2is) in patients with chronic kidney disease according to basic mechanisms, current recommendations, and future perspectives. Based on growing evidence from randomized, controlled trials, SGLT2is have proven their benefit on cardiac and renal adverse complications, and their indications expanded into the following five categories: glycemic control, reduction in atherosclerotic cardiovascular disease (ASCVD), heart failure, diabetic kidney disease, and nondiabetic kidney disease. Although kidney disease accelerates the progression of atherosclerosis, myocardial disease, and heart failure, so far, no specific drugs were available to protect renal function. Recently, two randomized trials, the DAPA-CKD and EMPA-Kidney, demonstrated the clinical benefit of the SGLT2is dapagliflozin and empagliflozin in improving the outcome in patients with chronic kidney disease. For the consistently positive results in cardiorenal protection, the SGLT2i represents an effective treatment to reduce the progression of kidney disease or death from cardiovascular causes in patients with and without diabetes mellitus.

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.

Nephroprotective Properties of Antidiabetic Drugs

Chronic kidney disease (CKD) is associated with increased morbidity and mortality, especially from cardiovascular (CV) causes, and especially in people with diabetes mellitus (DM). Already the presence of DM increases CV risk and potentiates the risk of CKD. Therefore, besides glycemic control, prevention and treatment of CKD to slow its progression are of clinical importance. A significant nephroprotective effect of novel antidiabetic drugs, namely sodium-glucose cotransporter 2 inhibitors (SGLT2-I) and glucagon-like peptide 1 receptor agonists (GLP1-RA), has been shown on top of their glucose-lowering effects and was confirmed in cardiovascular outcome trials. GLP1-RA mainly reduced the risk of macroalbuminuria, whereas SGLT2-I were also associated with a lower risk of declining glomerular filtration rate (GFR) over time. The nephroprotective effects of SGLT2-I are also evident in people without DM. According to current guidelines, SGLT2-I and/or GLP1-RA are recommended for people with DM who have chronic kidney disease and/or increased cardiovascular risk. However, other antidiabetic drugs offer nephroprotective properties, which will also be discussed in this review.

Ischemic tubular injury: Oxygen-sensitive signals and metabolic reprogramming

The kidneys are the most vulnerable organs to severe ischemic insult that results in cellular hypoxia under pathophysiological conditions. Large amounts of oxygen are consumed by the kidneys, mainly to produce energy for tubular reabsorption. Beyond high oxygen demand and the low oxygen supply, different other factors make kidneys vulnerable to ischemia which is deemed to be a major cause of acute kidney injury (AKI). On the other hand, kidneys are capable of sensing and responding to oxygen alternations to evade harms resulting from inadequate oxygen. The hypoxia-inducible factor (HIF) is the main conserved oxygen-sensing mechanism that maintains homeostasis under hypoxia through direct/indirect regulation of several genes that contribute to metabolic adaptation, angiogenesis, energy conservation, erythropoiesis, and so on. In response to oxygen availability, prolyl-hydroxylases (PHDs) control the HIF stability. This review focuses on the oxygen-sensing mechanisms in kidneys, particularly in proximal tubular cells (PTCs) and discusses the molecules involved in ischemic response and metabolic reprogramming. Moreover, the possible roles of non-coding RNAs (microRNAs and long non-coding RNAs) in the development of ischemic AKI are put forward.

Redox-driven cardioprotective effects of sodium-glucose co-transporter-2 inhibitors: comparative review

Sodium-glucose co-transporter-2 inhibitors are used in the treatment of diabetes but are also emerging as cardioprotective agents in heart diseases even in the absence of type 2 diabetes. In this paper, upon providing a short overview of common pathophysiological features of diabetes, we review the clinically reported cardio- and nephroprotective potential of sodium-glucose co-transporter-2 inhibitors currently available on the market, including Dapagliflozin, Canagliflozin, and Empagliflozin. To that end, we summarize findings of clinical trials that have initially drawn attention to the drugs' organ-protective potential, before providing an overview of their proposed mechanism of action. Since we particularly expect that their antioxidative properties will broaden the application of gliflozins from therapeutic to preventive care, special emphasis was put on this aspect.

The Pillars for Renal Disease Treatment in Patients with Type 2 Diabetes

The diabetes epidemic and the increasing number of patients with diabetic chronic vascular complications poses a significant challenge to health care providers. Diabetic kidney disease is a serious diabetes-mediated chronic vascular complication and represents a significant burden for both patients and society in general. Diabetic kidney disease not only represents the major cause of end stage renal disease but is also paralleled by an increase in cardiovascular morbidity and mortality. Any interventions to delay the development and progression of diabetic kidney disease are important to reduce the associated cardiovascular burden. In this review we will discuss five therapeutic tools for the prevention and treatment of diabetic kidney disease: drugs inhibiting the renin-angiotensin-aldosterone system, statins, the more recently recognized sodium-glucose co-transporter-2 inhibitors, glucagon-like peptide 1 agonists, and a novel non-steroidal selective mineralocorticoid receptor antagonist.

Anti-Diabetic Therapy and Heart Failure: Recent Advances in Clinical Evidence and Molecular Mechanism

Diabetic patients have a two- to four-fold increase in the risk of heart failure (HF), and the co-existence of diabetes and HF is associated with poor prognosis. In randomized clinical trials (RCTs), compelling evidence has demonstrated the beneficial effects of sodium-glucose co-transporter-2 inhibitors on HF. The mechanism includes increased glucosuria, restored tubular glomerular feedback with attenuated renin-angiotensin II-aldosterone activation, improved energy utilization, decreased sympathetic tone, improved mitochondria calcium homeostasis, enhanced autophagy, and reduced cardiac inflammation, oxidative stress, and fibrosis. The RCTs demonstrated a neutral effect of the glucagon-like peptide receptor agonist on HF despite its weight-reducing effect, probably due to it possibly increasing the heart rate via increasing cyclic adenosine monophosphate (cAMP). Observational studies supported the markedly beneficial effects of bariatric and metabolic surgery on HF despite no current supporting evidence from RCTs. Bromocriptine can be used to treat peripartum cardiomyopathy by reducing the harmful cleaved prolactin fragments during late pregnancy. Preclinical studies suggest the possible beneficial effect of imeglimin on HF through improving mitochondrial function, but further clinical evidence is needed. Although abundant preclinical and observational studies support the beneficial effects of metformin on HF, there is limited evidence from RCTs. Thiazolidinediones increase the risk of hospitalized HF through increasing renal tubular sodium reabsorption mediated via both the genomic and non-genomic action of PPARγ. RCTs suggest that dipeptidyl peptidase-4 inhibitors, including saxagliptin and possibly alogliptin, may increase the risk of hospitalized HF, probably owing to increased circulating vasoactive peptides, which impair endothelial function, activate sympathetic tones, and cause cardiac remodeling. Observational studies and RCTs have demonstrated the neutral effects of insulin, sulfonylureas, an alpha-glucosidase inhibitor, and lifestyle interventions on HF in diabetic patients.

Metabolic Syndrome and Cardiac Remodeling Due to Mitochondrial Oxidative Stress Involving Gliflozins and Sirtuins

PURPOSE OF REVIEW

To address the mechanistic pathways focusing on mitochondria dysfunction, oxidative stress, sirtuins imbalance, and other contributors in patient with metabolic syndrome and cardiovascular disease. Sodium glucose co-transporter type 2 (SGLT-2) inhibitors deeply influence these mechanisms. Recent randomized clinical trials have shown impressive results in improving cardiac function and reducing cardiovascular and renal events. These unexpected results generate the need to deepen our understanding of the molecular mechanisms able to generate these effects to help explain such significant clinical outcomes.

RECENT FINDINGS

Cardiovascular disease is highly prevalent among individuals with metabolic syndrome and diabetes. Furthermore, mitochondrial dysfunction is a principal player in its development and persistence, including the consequent cardiac remodeling and events. Another central protagonist is the renin-angiotensin system; the high angiotensin II (Ang II) activity fuel oxidative stress and local inflammatory responses. Additionally, sirtuins decline plays a pivotal role in the process; they enhance oxidative stress by regulating adaptive responses to the cellular environment and interacting with Ang II in many circumstances, including cardiac and vascular remodeling, inflammation, and fibrosis. Fasting and lower mitochondrial energy generation are conditions that substantially reduce most of the mentioned cardiometabolic syndrome disarrangements. In addition, it increases sirtuins levels, and adenosine monophosphate-activated protein kinase (AMPK) signaling stimulates hypoxia-inducible factor-1β (HIF-1 beta) and favors ketosis. All these effects favor autophagy and mitophagy, clean the cardiac cells with damaged organelles, and reduce oxidative stress and inflammatory response, giving cardiac tissue protection. In this sense, SGLT-2 inhibitors enhance the level of at least four sirtuins, some located in the mitochondria. Moreover, late evidence shows that SLGT-2 inhibitors mimic this protective process, improving mitochondria function, oxidative stress, and inflammation. Considering the previously described protection at the cardiovascular level is necessary to go deeper in the knowledge of the effects of SGLT-2 inhibitors on the mitochondria function. Various of the protective effects these drugs clearly had shown in the trials, and we briefly describe it could depend on sirtuins enhance activity, oxidative stress reduction, inflammatory process attenuation, less interstitial fibrosis, and a consequent better cardiac function. This information could encourage investigating new therapeutic strategies for metabolic syndrome, diabetes, heart and renal failure, and other diseases.

Exploring the molecular mechanism of Ling-Gui-Zhu-Gan decoction for the treatment of type 2 diabetes mellitus based on network pharmacology and molecular docking: A review

To investigate the mechanism of action of the classical formula Ling-Gui-Zhu-Gan (LGZG) decoction in treating type 2 diabetes mellitus based on network pharmacology and molecular docking. The active ingredients and targets of LGZG decoction were collected by the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform database and mapped using Cytoscape software to show their interrelationships. GeneCards, Pharmacogenomics Knowledge Base, OMIM, Therapeutic Target Database, and Drugbank databases were used to obtain targets related to type 2 diabetes; protein-protein interaction networks were established with the help of the STRING platform. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed on selected core targets with the help of the Metascape platform. Finally, the AutoDock platform was used to perform molecular docking and display the results by Pymol software. One hundred twenty-one active ingredients, 216 effective target genes, 11,277 type 2 diabetes mellitus-related genes, 210 crossover genes, and 18 core genes were obtained for LGZG decoction. The results obtained by Kyoto Encyclopedia of Genes and Genomes indicated that the advanced glycosylation end products-receptor of advanced glycosylation end products signaling pathway, the phosphatidylinositol 3 kinase-Akt signaling pathway, and HIF-1 signaling pathway might be the key signaling pathways. Molecular docking showed that the binding energy of quercetin, kaempferol, naringenin, and licorice chalcone A to the core target genes were all <5.0 kJ-mol-1, with good affinity. In this study, the potential active ingredients and mechanisms of action of LGZG decoction in the treatment of type 2 diabetes were initially investigated, which provided a basis for the in-depth study of its drug basis and mechanisms of action.

High glucose induced HIF-1α/TREK1 expression and myometrium relaxation during pregnancy

Background

The incidence of gestational diabetes mellitus (GDM) is increasing worldwide. GDM patients have a significantly higher rate of cesarean section and postpartum hemorrhage, suggesting changes in uterine contractility. TWIK-1-related potassium channel (TREK1) expressed in the pregnant uterus and its role in uterine contraction. In this study, we examined the expression of HIF-1α and TREK1 proteins in GDM uterine and investigated whether high glucose levels are involved in the regulation of human uterine smooth muscle cells (HUSMCs) contraction through TREK1, and verified the role of HIF-1α in this process.

Methods

Compared the uterine contractility between GDM and normal patients undergoing elective lower segment cesarean section. The HUSMCs were divided into normal glucose group, high glucose group, normal glucose with CoCl2 group, CoCl2 with echinomycin/L-Methionine group, and high glucose with echinomycin/L-Methionine group; Compare the cell contractility of each group. Compared the expression of hypoxia-inducible factor-1α (HIF-1α) and TREK1 protein in each group.

Results

The contractility of human uterine strips induced by both KCl and oxytocin was significantly lower in patients with GDM compared with that in normal individuals, with increased TREK1 and HIF-1α protein expression. The contractility of cultured HUSMCs was significantly decreased under high glucose levels, which was consistent with increased expression of HIF-1α and TREK1 proteins. The contractility of HUSMCs was decreased when hypoxia was induced by CoCl2 and increased when hypoxia was inhibited by echinomycin. The TREK1 inhibitor L-methionine also recovered the decreased contractility of HUSMCs under high glucose levels or hypoxia.

Discussion

The high glucose levels decreased the contractility of the myometrium, and increased expression of HIF-1a and TREK1 proteins play a role in changes in uterus contractility.

Recent progress of biocompatible carbon dots in hypoxia-related fields

Almost all eukaryotes need oxygen to maintain regular physiological activities. When the organism is under hypoxic situation for a persistent or periodic, it will induce irreversible physiological disorders and even pathological results. Hypoxia is closely related to the pathogenesis of metabolic diseases, cancer, chronic heart disease and kidney disease, myocardial ischemia, as well as reproductive diseases like preeclampsia and endometriosis. Therefore, monitoring and treatment of hypoxia have important implications for the pathophysiology of human-related diseases. Carbon dots (CDs) are emerging nanomaterials developed after 2004 with excellent performance, and have broad application potential in variousdomains likeoptical, biomedicine, energy. Advanced hypoxia therapeutics should be integrated with monitoring and treatment, and CDs with excellent performance are good potential options when sensing is combined with various therapeutic methods. Some researchers have also begun to carry out research in related fields and achieved some results. This article aims to clarify the various applications of CDs in hypoxia-related fields in recent years, including hypoxia sensing and hypoxia tumor theranostics. Finally, the possible challenges and prospects for the application of CDs in hypoxia-related fields are discussed.

Metabolic-associated fatty liver disease increases the risk of end-stage renal disease in patients with biopsy-confirmed diabetic nephropathy: a propensity-matched cohort study

AIMS

To investigate the relationship between metabolic-associated fatty liver disease (MAFLD) and end-stage renal disease (ESRD) in patients with biopsy-confirmed diabetic nephropathy (DN).

METHODS

A total of 316 participants with biopsy-confirmed DN between January 2008 and December 2019 were retrospectively assessed. Kaplan-Meier curve and Cox proportional hazard models were used to compare the risk of incident ESRD in 50 patients with MAFLD and 50 patients without MAFLD, after using propensity score matching (PSM) to address the imbalances of sex, age, baseline-estimated glomerular filtration rate, serum albumin, 24-h urine protein, hemoglobin and systolic blood pressure.

RESULTS

During the median follow-up period of 3 years, there were 19 ESRD outcome events (19%) in PSM cohort. Kaplan-Meier curve analysis suggested that renal survival significantly deteriorated in patients with MAFLD versus those without MAFLD (p = 0.021). Additionally, the hazard ratios (95% confidence interval) of MAFLD were 3.12 (1.09-8.95, p = 0.035), 3.36 (1.09-10.43, p = 0.036), 3.66 (1.22-10.98, p = 0.021), 4.25 (1.34-13.45, p = 0.014), 3.11 (1.08-8.96, p = 0.035) and 5.84 (1.94-18.5, p = 0.003) after adjustment for six models, including demographic, clinical and pathological characteristics as well as medication use at the time of renal biopsy, respectively. Besides, patients with higher liver fibrosis score had a greater possibility of ESRD, comparing to those with lower liver fibrosis score (p = 0.002).

CONCLUSIONS

MAFLD increases the risk of incident ESRD in patients with biopsy-proven DN. Further research is needed to determine whether treatment targeting MAFLD improves the prognosis of DN.

Therapeutic Advances in Diabetic Kidney Disease

Although sodium glucose co-transporter type 2 (SGLT-2) inhibitors were initially introduced as glucose-lowering medications, it was later discovered that cardiorenal protection is the most important treatment effect of these agents. A triad of landmark trials consistently showed the benefits of SGLT-2 inhibitors on kidney and cardiovascular outcomes in patients with chronic kidney disease (CKD), irrespective of the presence or absence of Type 2 diabetes (T2D). Furthermore, finerenone is a novel, selective, nonsteroidal mineralocorticoid receptor antagonist (MRA) that safely and effectively improved cardiorenal outcomes in a large Phase 3 clinical trial program that included >13,000 patients with T2D and a wide spectrum of CKD. These two drug categories have shared and distinct mechanisms of action, generating the hypothesis that an overadditive cardiorenal benefit with their combined use may be biologically plausible. In this article, we describe the mechanism of action, and we provide an overview of the evidence for cardiorenal protection with SGLT-2 inhibitors and the nonsteroidal MRA finerenone in patients with CKD associated with T2D.

Increase in hematocrit with SGLT-2 inhibitors - Hemoconcentration from diuresis or increased erythropoiesis after amelioration of hypoxia?

BACKGROUND AND AIMS

The SGLT2-inhibitors significantly reduce heart failure hospitalization and progression to end-stage kidney disease. An increase in hemoglobin/hematocrit is seen with SGLT2i-inhibitor treatment. This increase has been attributed to hemoconcentration resulting from a diuretic effect. In this review, we present evidence suggesting that the hematocrit increase is not due to hemoconcentration, but to an increase in erythropoiesis due to amelioration of hypoxia and more efficient erythropoietin production with SGLT2-inhibitor treatment.

METHODS

We performed a detailed review of the literature in PubMed for articles describing various mechanisms linking hematocrit increase with SGLT2-inhibitor use to their cardio-renal benefits.

RESULTS

The best predictor of cardio-renal benefits with SGLT2-inhibitors is an increase in hematocrit and hemoglobin. If this hemoconcentration is a results of diuresis, this would be associated with volume contraction and a deterioration in renal function, as seen with long-term diuretic use. This is the opposite of what is seen with the use of SGLT2-inhibitors, which are associated with long-term preservation of renal function. There is now growing evidence that the increase in hematocrit can be attributed to an increase in erythropoiesis due to amelioration of renal hypoxia and more efficient erythropoietin production with SGLT2-inhibitor treatment. Increased erythropoiesis leads to an increase in RBC count which improves myocardial/renal tissue oxygenation and function.

CONCLUSION

The increase in hematocrit with SGLT2i treatment is not due to hemoconcentration, but to an increase in erythropoiesis due to amelioration of hypoxia and more efficient erythropoietin production with SGLT2i treatment.

Kidney-Protective Effects of SGLT2 Inhibitors

The sodium-glucose cotransporter 2 (SGLT2) inhibitors have become an integral part of clinical practice guidelines to slow the progression of CKD in patients with and without diabetes mellitus. Although initially developed as antihyperglycemic drugs, their effect on the kidney is multifactorial resulting from profuse glycosuria and natriuresis consequent to their primary site of action. Hemodynamic and metabolic changes ensue that mediate kidney-protective effects, including ( 1 ) decreased workload of proximal tubular cells and prevention of aberrant increases in glycolysis, contributing to a decreased risk of AKI; ( 2 ) lowering of intraglomerular pressure by activating tubular glomerular feedback and reductions in BP and tissue sodium content; ( 3 ) initiation of nutrient-sensing pathways reminiscent of starvation activating ketogenesis, increased autophagy, and restoration of carbon flow through the mitochondria without production of reactive oxygen species; ( 4 ) body weight loss without a reduction in basal metabolic rate due to increases in nonshivering thermogenesis; and ( 5 ) favorable changes in quantity and characteristics of perirenal fat leading to decreased release of adipokines, which adversely affect the glomerular capillary and signal increased sympathetic outflow. Additionally, these drugs stimulate phosphate and magnesium reabsorption and increase uric acid excretion. Familiarity with kidney-specific mechanisms of action, potential changes in kidney function, and/or alterations in electrolytes and volume status, which are induced by these widely prescribed drugs, will facilitate usage in the patients for whom they are indicated.

Research Update on the Pathophysiological Mechanisms of Heart Failure with Preserved Ejection Fraction

Heart failure (HF) is a serious clinical syndrome, usually occurs at the advanced stage of various cardiovascular diseases, featured by high mortality and rehospitalization rate. According to left ventricular (LV) ejection fraction (LVEF), HF has been categorized as HF with reduced EF (HFrEF; LVEF<40%), HF with mid-range EF (HFmrEF; LVEF 40-49%), and HF with preserved EF (HFpEF; LVEF ≥50%). HFpEF accounts for about 50% of cases of heart failure and has become the dominant form of heart failure. The mortality of HFpEF is similar to that of HFrEF. There are no welldocumented treatment options that can reduce the morbidity and mortality of HFpEF now. Understanding the underlying pathological mechanisms is essential for the development of novel effective therapy options for HFpEF. In recent years, significant research progress has been achieved on the pathophysiological mechanism of HFpEF. This review aimed to update the research progress on the pathophysiological mechanism of HFpEF.

Is there any robust evidence showing that SGLT2 inhibitor use predisposes to acute kidney injury?

A novel class of oral glucose lowering drugs, sodium-glucose co-transporter type 2 inhibitors (SGLT2is), has shown additional beneficial effects on body weight, serum uric acid levels, blood pressure, and cardiac and renal function. Conflicting data have been published regarding the potential risk of acute kidney injury (AKI) when using SGLT2is. Aim of this manuscript was to review the current literature on this issue. SGLT2is induce a mild acute decline in estimated glomerular filtration rate, attributed to the effect of proximal tubular natriuresis on tubuloglomerular feedback through increased macula densa sodium delivery, leading to afferent arteriole vasoconstriction and reduced intraglomerular pressure. This functional effect with a subsequent rise in serum creatinine fulfills the creatinine-based criteria for AKI, as defined in clinical practice and trial settings. Other proposed potential mechanisms as to how SGLT2is lead to AKI include osmotic diuresis leading to volume depletion, increased urinary uric acid levels, intratubular oxidative stress, local inflammation and tubular injury. Despite the warning published by the US Food and Drug Administration in 2016 about a potential risk of AKI and the report of some clinical cases of AKI after treatment with SGLT2is, large observational real-life retrospective studies, randomized controlled trials and propensity-matched analyses of data from clinical practice unambiguously demonstrate that SGLT2is are safe for the kidney and do not predispose to AKI. In conclusion, while we can probably stop worrying about AKI risk when using SGLT2is, the question whether these agents should be withheld in the presence of clinical situations at high risk for AKI remains unaddressed.

Lower Blood Oxygen Saturation is Associated With Microvascular Complications in Individuals With Type 1 Diabetes

CONTEXT

Blood oxygen saturation (SpO2) is lower in type 1 diabetes (T1D) compared with nondiabetic controls. Hypoxia (low tissue oxygenation) is thought to be a risk factor for progression of diabetic complications, but it is unknown whether hypoxemia (low SpO2) is associated with diabetic complications.

OBJECTIVE

To test if hypoxemia is associated with presence of diabetic complications in T1D.

DESIGN, SETTING, AND METHODS

Cross-sectional study in persons with T1D divided by a previously suggested threshold in low (<96%) and high (≥96%) SpO2, measured in the supine position with pulse oximetry. Complications included albuminuria (2 of 3 consecutive measurements ≥30 mg/g), any diabetic retinopathy, neuropathy, and history of cardiovascular disease (CVD). Odds ratios were adjusted for age, diabetes duration, sex, smoking, physical activity, body mass index, systolic blood pressure, and blood hemoglobin.

RESULTS

We included 659 persons, 23 (3.5%) with low and 636 (96.5%) with high SpO2. In total, 151 (23%) had albuminuria, 233 (36%) had retinopathy, 231 (35%) had neuropathy, and 72 (11%) had CVD. The adjusted odds ratio (95% CI, P value) for low vs high SpO2 was 3.4 (1.3-8.7, P = 0.01) for albuminuria, 2.8 (1.0-7.5, P = 0.04) for retinopathy, 5.8 (1.8-18.6, P < 0.01) for neuropathy, and nonsignificant for CVD (0.6 [0.2-2.4, P = 0.51]).

CONCLUSIONS

SpO2 below 96% was associated with increased presence of albuminuria, retinopathy, and neuropathy in T1D, but not with CVD. Whether hypoxemia could be a target of intervention to prevent progression in microvascular disease in type 1 diabetes should be investigated.

Sub-analyses of the DAPA-CKD study: new data on the use of sodium-glucose cotransporter type 2 inhibitor in the treatment of chronic kidney disease

Sodium-glucose cotransporter inhibitors updated their position in the therapy of patients with type 2 diabetes mellitus due to proven nephro- and cardioprotective effects. The DAPA-CKD study, performed among individuals with CKD of various etiologies, was also conducted in a mixed population, including patients without type 2 diabetes, showed the ability of dapagliflozin to reduce the risk of the primary combined endpoint (eGFR15 ml/min/1.73 m2, the need for chronic dialysis or kidney transplantation, time to renal or cardiovascular death), and certain secondary endpoints. Due to the inclusion of dapagliflozin into the treatment of the patients with CKD of not only the diabetic origin and the expected subsequent significant expansion of the patient population with indications for the use of this drug, the review of the results of the sub-analyses of DAPA-CKD study may be of interest to the clinicians.

Hypoxia-Inducible Factor-Prolyl Hydroxyl Domain Inhibitors: From Theoretical Superiority to Clinical Noninferiority Compared with Current ESAs?

Anemia is a common complication of chronic kidney disease; it is mainly treated with erythropoiesis-stimulating agents (ESAs) and iron. Experimental studies extensively investigated the mechanisms involved in the body's response to hypoxia and led to the discovery of the hypoxia-inducible factor (HIF) pathway and the enzymes regulating its function. HIF-prolyl-hydroxyl domain (PHD) inhibitors are a new class of oral drugs developed to treat anemia in chronic kidney disease. By inhibiting the function of PHD enzymes, they mimic the exposure to moderate hypoxia and stimulate the production of endogenous erythropoietin and very likely increase iron availability. Some data also suggest that their efficacy and, consequently, dose needs are less influenced by inflammation than ESAs. Overall, data from phases 2 and 3 clinical development showed efficacy in anemia correction and maintenance for all of the class molecules compared with placebo (superiority) or erythropoiesis-stimulating agents (noninferiority). Three molecules, roxadustat, vadadustat, and daprodustat, underwent extensive clinical investigation to assess their safety on hard cardiovascular end points, mortality, and special interest events (including cancer and thrombosis). Aside from vadadustat in the nondialysis population, at the prespecified primary analyses, all three molecules met the noninferiority margin for the risk of major cardiovascular events compared with erythropoiesis-stimulating agents or placebo. The reason for this discrepancy is difficult to explain. Other safety signals came from secondary analyses of some of the other randomized clinical trials, including a higher incidence of thrombosis. A more extensive clinical experience with post-marketing data on hard safety issues is needed to define better when and how to use HIF-PHD inhibitors compared with already available ESAs.

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.

Proximal tubular epithelia-specific transcriptomics of diabetic mice treated with dapagliflozin

Based on recent clinical trials using sodium-glucose co-transporter 2 inhibitor (SGLT2i) demonstrating the significant improvement of outcomes of diabetic kidney disease (DKD), the paradigm shift from “glomerulocentric” to “tubule centric” pathophysiology in DKD progression has been highlighted. Several responsible mechanisms for renoprotective effects by SGLT2i have been proposed recently, but the changes in proximal tubule-specific gene expression by SGLT2i in diabetic mice have not been elucidated. We report the analysis of the proximal tubular-specific pathway, demonstrating the downregulation of oxidative phosphorylation in dapagliflozin-treated db/db mice, a type 2 diabetic model. After 8-week treatment of dapagliflozin for db/db mice having a proximal tubule-specific tdTomato reporter, tdTomato-positive cells were isolated by FACS. Pathway analysis of RNA sequencing of isolated tubular epithelia revealed that oxidative phosphorylation was downregulated in dapagliflozin-treated mice. However, depletion of renal tissue ATP content in db/db mice was ameliorated by dapagliflozin administration. Pimonidazole staining demonstrated renal cortical tissue hypoxia in db/db mice, which was improved by dapagliflozin administration. This study suggests that dapagliflozin can ameliorate the excessive oxygen and ATP consumption, and subsequent tissue hypoxia in the diabetic kidney, which may explain, in part, the responsible mechanisms of the renoprotective effects of dapagliflozin.

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Oxidative phosphorylation is downregulated by dapagliflozin in the proximal tubules of diabetic kidneys.

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Renal tissue ATP content increased in dapagliflozin-treated diabetic mice.

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Dapagliflozin improved renal cortical hypoxia in type 2 diabetic mice.

Cardiorenal protection of SGLT2 inhibitors—Perspectives from metabolic reprogramming

Sodium-glucose co-transporter 2 (SGLT2) inhibitors, initially developed as a novel class of anti-hyperglycaemic drugs, have been shown to significantly improve metabolic indicators and protect the kidneys and heart of patients with or without type 2 diabetes mellitus. The possible mechanisms mediating these unexpected cardiorenal benefits are being extensively investigated because they cannot solely be attributed to improvements in glycaemic control. Notably, emerging data indicate that metabolic reprogramming is involved in the progression of cardiorenal metabolic diseases. SGLT2 inhibitors reprogram systemic metabolism to a fasting-like metabolic paradigm, involving the metabolic switch from carbohydrates to other energetic substrates and regulation of the related nutrient-sensing pathways, which might explain some of their cardiorenal protective effects. In this review, we will focus on the current understanding of cardiorenal protection by SGLT2 inhibitors, specifically its relevance to metabolic reprogramming.

Gene-Based Network Analysis Reveals Prognostic Biomarkers Implicated in Diabetic Tubulointerstitial Injury

Background

Diabetic nephropathy (DN), a significant cause of chronic kidney disease (CKD), is a devastating disease worldwide.

Objective

The aim of this study was to reveal crucial genes closely linked to the molecular mechanism of tubulointerstitial injury in DN.

Methods

The Gene Expression Omnibus (GEO) database was used to download the datasets. Based on this, a weighted gene coexpression network analysis (WGCNA) network was constructed to detect DN-related modules and hub genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichments were performed on the selected hub genes and modules. Least absolute shrinkage and selection operator (LASSO) Cox regression analysis was performed on the obtained gene signature.

Results

The WGCNA network was constructed based on 3019 genes, and nine gene coexpression modules were generated. A total of 57 genes, including 34 genes in the magenta module and 23 genes in the purple module, were adapted as hub genes. 61 significantly downregulated and 119 upregulated genes were screened as differentially expressed genes (DEGs). 25 overlapping genes between hub genes chosen from WGCNA and DEG were identified. Through LASSO analysis, a 9-gene signature may be a potential prognostic biomarker for DN. To further explore the potential mechanism of DN, the different immune cell infiltrations between tubulointerstitial samples of DN and healthy samples were estimated.

Conclusions

This bioinformatics study identified CX3CR1, HRG, LTF, TUBA1A, GADD45B, PDK4, CLIC5, NDNF, and SOCS2 as candidate biomarkers for the diagnosis of DN. Moreover, DN tends to own a higher proportion of memory B cell.

Sodium-glucose co-transporter 2 inhibitors and hematopoiesis

Many patients with diabetes mellitus, especially those with chronic kidney disorders, have some degree of anemia due to a spectrum of causes and underlying pathophysiologic pathways. As such, enhancement in erythropoiesis is important in these patients. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are a relatively new class of antidiabetic drugs with confirmed protective effects in kidney and cardiovascular tissues. Recent evidence suggests that these drugs may provide additional benefits in enhancing hematopoietic processes in diabetic patients. Though the exact mediating pathways have not been fully elucidated, cellular mechanisms are likely involved. In the current study, we present the potential pathways by which SGLT2i may modulate hematopoiesis and stimulate erythropoiesis.

Therapeutic Role of Curcumin in Diabetes: An Analysis Based on Bioinformatic Findings

BACKGROUND

Diabetes is an increasingly prevalent global disease caused by the impairment in insulin production or insulin function. Diabetes in the long term causes both microvascular and macrovascular complications that may result in retinopathy, nephropathy, neuropathy, peripheral arterial disease, atherosclerotic cardiovascular disease, and cerebrovascular disease. Considerable effort has been expended looking at the numerous genes and pathways to explain the mechanisms leading to diabetes-related complications. Curcumin is a traditional medicine with several properties such as being antioxidant, anti-inflammatory, anti-cancer, and anti-microbial, which may have utility for treating diabetes complications. This study, based on the system biology approach, aimed to investigate the effect of curcumin on critical genes and pathways related to diabetes.

METHODS

We first searched interactions of curcumin in three different databases, including STITCH, TTD, and DGIdb. Subsequently, we investigated the critical curated protein targets for diabetes on the OMIM and DisGeNET databases. To find important clustering groups (MCODE) and critical hub genes in the network of diseases, we created a PPI network for all proteins obtained for diabetes with the aid of a string database and Cytoscape software. Next, we investigated the possible interactions of curcumin on diabetes-related genes using Venn diagrams. Furthermore, the impact of curcumin on the top scores of modular clusters was analysed. Finally, we conducted biological process and pathway enrichment analysis using Gene Ontology (GO) and KEGG based on the enrichR web server.

RESULTS

We acquired 417 genes associated with diabetes, and their constructed PPI network contained 298 nodes and 1651 edges. Next, the analysis of centralities in the PPI network indicated 15 genes with the highest centralities. Additionally, MCODE analysis identified three modular clusters, which highest score cluster (MCODE 1) comprises 19 nodes and 92 edges with 10.22 scores. Screening curcumin interactions in the databases identified 158 protein targets. A Venn diagram of genes related to diabetes and the protein targets of curcumin showed 35 shared proteins, which observed that curcumin could strongly interact with ten of the hub genes. Moreover, we demonstrated that curcumin has the highest interaction with MCODE1 among all MCODs. Several significant biological pathways in KEGG enrichment associated with 35 shared included the AGE-RAGE signaling pathway in diabetic complications, HIF-1 signaling pathway, PI3K-Akt signaling pathway, TNF signaling, and JAK-STAT signaling pathway. The biological processes of GO analysis were involved with the cellular response to cytokine stimulus, the cytokine-mediated signaling pathway, positive regulation of intracellular signal transduction and cytokine production in the inflammatory response.

CONCLUSION

Curcumin targeted several important genes involved in diabetes, supporting the previous research suggesting that it may have utility as a therapeutic agent in diabetes.

Antifibrotic Agents for the Management of CKD: A Review

Kidney fibrosis is a hallmark of chronic kidney disease (CKD) and a potential therapeutic target. However, there are conceptual and practical challenges to directly targeting kidney fibrosis. Whether fibrosis is mainly a cause or a consequence of CKD progression has been disputed. It is unclear whether specifically targeting fibrosis is feasible in clinical practice because most drugs that decrease fibrosis in preclinical models target additional and often multiple pathogenic pathways (eg, renin-angiotensin-aldosterone system blockade). Moreover, tools to assess whole-kidney fibrosis in routine clinical practice are lacking. Pirfenidone, a drug used for idiopathic pulmonary fibrosis, is undergoing a phase 2 trial for kidney fibrosis. Other drugs in use or being tested for idiopathic pulmonary fibrosis (eg, nintedanib, PRM-151, epigallocatechin gallate) are also potential candidates to treat kidney fibrosis. Novel therapeutic approaches may include antagomirs (eg, lademirsen) or drugs targeting interleukin 11 or NKD2 (WNT signaling pathway inhibitor). Reversing the dysfunctional tubular cell metabolism that leads to kidney fibrosis offers additional therapeutic opportunities. However, any future drug targeting fibrosis of the kidneys should demonstrate added benefit to a standard of care that combines renin-angiotensin system with mineralocorticoid receptor (eg, finerenone) blockade or with sodium/glucose cotransporter 2 inhibitors.

Sodium-glucose cotransporter 2 inhibitors as adjunct therapy for type 1 diabetes and the benefit on cardiovascular and renal disease evaluated by Steno risk engines

AIMS

Sodium-glucose cotransporter inhibitors (SGLTi) have beneficial cardiovascular and renal effects in persons with type 2 diabetes. No studies have shown whether this can be demonstrated in type 1 diabetes (T1D). We aimed to estimate the risk of cardiovascular disease (CVD) and end-stage kidney disease (ESKD) in persons with T1D with and without treatment with SGLTi.

METHODS

The study is based on 3660 adults with T1D. The Steno Type 1 Risk Engines were used to calculate 5-year risks of ESKD and 5- and 10-year risk of CVD. The effect of SGLTi was simulated by changing the HbA_1c and systolic blood pressure values in accordance with results from the DEPICT studies with mean (standard deviation (SD)) of -3.6 (0.9) mmol/mol (-2.5 % (2.2)) and -1.12 (2.8) mmHg. eGFR and albuminuria were changed in accordance with results from the Tandem studies; no change in eGFR and mean (SD) %-change in albuminuria of -23.7 (12.9).

RESULTS

We found a 5-year CVD relative risk reduction of 6.1 % (95%CI 5.9,6.3) and 11.1 % (10.0,12.2) in the subgroup with albuminuria with similar results for the 10-year CVD risk. For the estimated 5-year risk of ESKD, we found a relative risk reduction of 5.3 % (5.1,5.4) with 7.6 % (6.9,8.4) in the subgroup with albuminuria.

CONCLUSION

We found a significant CVD and ESKD risk reduction, especially in the subgroup with albuminuria.

SGLT2 inhibitor dapagliflozin attenuates cardiac fibrosis and inflammation by reverting the HIF-2α signaling pathway in arrhythmogenic cardiomyopathy

Excessive cardiac fibrosis and inflammation aberrantly contribute to the progressive pathogenesis of arrhythmogenic cardiomyopathy (ACM). Whether sodium-glucose cotransporter-2 inhibitor (SGLT2i), as a new hypoglycemic drug, benefits ACM remains unclear. Cardiomyocyte-specific Dsg2 exon-11 knockout and wild-type (WT) littermate mice were used as the animal model of ACM and controls, respectively. Mice were administered by gavage with either SGLT2i dapagliflozin (DAPA, 1 mg/kg/day) or vehicle alone for 8 weeks. HL-1 cells were treated with DAPA to identify the molecular mechanism in vitro. All mice presented normal glucose homeostasis. DAPA not only significantly ameliorated cardiac dysfunction, adverse remodeling, and ventricular dilation in ACM but also attenuated ACM-associated cardiac fibrofatty replacement, as demonstrated by the echocardiography and histopathological examination. The protein expressions of HIF-2α and HIF-1α were decreased and increased respectively in cardiac tissue of ACM, which were compromised after DAPA treatment. Additionally, NF-κB P65 and IκB phosphorylation, as well as fibrosis indicators (including TGF-β, α-SMA, Collagen I, and Collagen III) were increased in ACM. However, these trends were markedly suppressed by DAPA treatment. Consistent with these results in vitro, DAPA alleviated the IκB phosphorylation and NF-κB p65 transcriptional activity in DSG2-knockdown HL-1 cells. Interestingly, the elective HIF-2α inhibitor PT2399 almost completely blunted the DAPA-mediated downregulation of indicators concerning cardiac fibrosis and inflammation. SGLT2i attenuated the ACM-associated cardiac dysfunction and adverse remodeling in a glucose-independent manner by suppressing cardiac fibrosis and inflammation via reverting the HIF-2α signaling pathway, suggesting that SGLT2i is a novel and available therapy for ACM.

Amelioration of Murine Diabetic Nephropathy with a SGLT2 Inhibitor Is Associated with Suppressing Abnormal Expression of Hypoxia-Inducible Factors

Diabetic nephropathy (DN), once manifested, is unlikely to completely recover. Factors that influence DN progression were explored by investigating the process of glomerulosclerosis and interstitial fibrosis and chronological changes in glucose, albuminuria, hyperfiltration, and expressions of sodium-glucose cotransporter 2 (SGLT2) and hypoxia-inducible factors (HIFs) up to 50 weeks in inducible cAMP early repressor transgenic mice, a model of severe DN. Long-term intervention with the SGLT2 inhibitor canagliflozin or islet transplantation or heminephrectomy was used. Inducible cAMP early repressor transgenic mice exhibited progressive diabetic glomerulosclerosis and mild interstitial fibrosis, and expressed extensive HIF-1α and HIF-2α in glomerulus and tubules, with sustained hyperfiltration up to 50 weeks. Canagliflozin ameliorated glomerulosclerosis/interstitial fibrosis gradually and reduced HIF overexpression. Islet-transplanted mice exhibited no amelioration. None of the heminephrectomized diabetic mice survived the hyperfiltration overload, but all of the canagliflozin-treated mice survived with re-expressions of HIF-1α and HIF-2α. These results suggest that persistent glomerular hyperfiltration might initiate glomerular injury, and persistent overexpression of HIFs could promote the development of glomerulosclerosis and interstitial fibrosis. Canagliflozin attenuated both changes. Oxidative stress or hypoxia was undetectable in this model. The abnormal expression of HIF-1α and HIF-2α may be a potential therapeutic target for preventing glomerulosclerosis and interstitial fibrosis.

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

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

Kidney oxygenation, perfusion and blood flow in people with and without type 1 diabetes

Background

We used magnetic resonance imaging (MRI) to study kidney energetics in persons with and without type 1 diabetes (T1D).

Methods

In a cross-sectional study, 15 persons with T1D and albuminuria and 15 non-diabetic controls (CONs) underwent multiparametric MRI (3 Tesla Philips Scanner) to quantify renal cortical and medullary oxygenation (R₂*, higher values correspond to higher deoxyhaemoglobin concentration), renal perfusion (arterial spin labelling) and renal artery blood flow (phase contrast). Analyses were adjusted for age, sex, systolic blood pressure, plasma haemoglobin, body mass index and estimated glomerular filtration rate (eGFR).

Results

Participants with T1D had a higher median (Q1; Q3) urine albumin creatinine ratio (UACR) than CONs [46 (21; 58) versus 4 (3; 6) mg/g; P < .0001] and a lower mean ± SD eGFR (73 ± 32 mL/min/1.73 m² versus 88 ± 15 mL/min/1.73 m²;  P = .12), although not significantly. Mean medullary R₂* was lower in T1D (34 ± 6/s versus 38 ± 5/s; P < .01) corresponding to a higher oxygenation. R₂* was not different in the cortex. Cortical perfusion was lower in T1D (163 ± 40 versus 224 ± 49 mL/100 g/min; P < .001). Renal artery blood flow was lower in T1D than in CONs (360 ± 130 versus 430 ± 113 mL/min; P = .05). In T1D, lower cortical oxygenation and renal artery blood flow were both associated with higher UACR and lower eGFR (P < .05).

Conclusions

Participants with T1D and albuminuria exhibited higher medullary oxygenation than CONs, despite lower cortical perfusion and renal artery blood flow. This might reflect perturbed kidney energetics leading to a higher setpoint of medullary oxygenation in T1D. Lower cortical oxygenation and renal artery blood flow were associated with higher UACR and lower eGFR in T1D.

Acute and Long-Term Treatment With Dapagliflozin and Association With Serum Soluble Urokinase Plasminogen Activator Receptor

Background: Elevated soluble urokinase plasminogen activator receptor (suPAR) is highly associated with increased risk of diabetic complications. Dapagliflozin is a drug inhibiting the sodium-glucose co-transporter 2 in the kidney to decrease blood glucose, while also decreasing risk of kidney disease, heart failure, and death. Therefore, we have investigated suPAR as a monitor for treatment effect with dapagliflozin in diabetes. Methods: suPAR was measured in two double-blinded randomized clinical cross-over trials. The first trial investigated the effect of a single dose dapagliflozin 50 mg or placebo 12 h after intake, in individuals with type 1 diabetes and albuminuria. The second trial investigated the effect of a daily dose dapagliflozin 10 mg or placebo for 12 weeks, in individuals with type 2 diabetes and albuminuria. suPAR was measured in serum samples taken, in the acute trial, after treatment with dapagliflozin and placebo, and in the long-term trial, before and after treatment with dapagliflozin and placebo. Effect of dapagliflozin on suPAR levels were assessed using paired t-test. Results: 15 participants completed the acute trial and 35 completed the long-term trial. Mean difference in suPAR between dapagliflozin and placebo in the acute trial after 12 h was 0.70 ng/ml (95% CI: 0.66; 1.33, p = 0.49). In the long-term trial the mean difference was 0.06 ng/ml (95% CI -0.15; 0.27, p = 0.57). Conclusion: Based on our findings we conclude that suPAR is not a feasible marker to monitor the effect of treatment with dapagliflozin. Thus, a further search of suitable markers must continue.

Bibliometric Study of Trends in the Diabetic Nephropathy Research Space from 2016 to 2020

Background

Diabetic nephropathy (DN) is one of the most common microvascular complications of diabetes mellitus (DM), but no bibliometric studies pertaining to DN have been published within the last 5 years.

Objectives

Most prior studies have focused on specific problems in the DN field. This study attempts to sort out and visualize the knowledge framework in this research space from a holistic and highly generalized perspective. Readers can quickly understand and master the knowledge regarding DN research conducted from 2016 to 2020, in addition to predicting future research hotspots and possible directions for development in this field in a comprehensive and scientifically valid manner.

Methods

Literature information, discourse matrices, and co-occurrence matrices were generated using BICOMB. gCLUTO was used for biclustering analyses and visualization. Strategic diagrams were generated using GraphPad Prism 5. The social network analysis (SNA) was analyzed and plotted using Ucinet 6.0 and Netdraw.

Results

In total, 55 high-frequency MeSH terms/MeSH subheadings were selected and grouped into 5 clusters in a biclustering analysis. These analyses revealed that extensive studies of the etiology, diagnosis, and treatment of DN have been conducted over the last 5 years, while further research regarding DN-related single nucleotide polymorphisms, miRNAs, and signal transduction are warranted as these research areas remain relatively immature.

Conclusion

Together, these results outline a robust knowledge structure pertaining to the field of DN-related research over the last 5 years, providing a valuable resource for readers by enabling the easy comprehension of relevant information. In addition, this analysis highlights predicted DN-related research directions and hotspots.

New Approaches to Diabetic Nephropathy from Bed to Bench

Diabetic nephropathy (DN) is the main cause of end-stage kidney disease (ESKD). DN-related ESKD has the worst prognosis for survival compared with other causes. Due to the complex mechanisms of DN and the heterogeneous presentations, unmet needs exist for the renal outcome of diabetes mellitus. Clinical evidence for treating DN is rather solid. For example, the first Kidney Disease: Improving Global Outcomes (KDIGO) guideline was published in October 2020: KDIGO Clinical Practice Guideline for Diabetes Management in Chronic Kidney Disease. In December of 2020, the International Society of Nephrology published 60 (+1) breakthrough discoveries in nephrology. Among these breakthroughs, four important ones after 1980 were recognized, including glomerular hyperfiltration theory, renal protection by renin-angiotensin system inhibition, hypoxia-inducible factor, and sodium-glucose cotransporter 2 inhibitors. Here, we present a review on the pivotal and new mechanisms of DN from the implications of clinical studies and medications.

Plasma or Urine Neutrophil Gelatinase-Associated Lipocalin (NGAL): Which Is Better at Detecting Chronic Kidney Damage in Type 2 Diabetes?

Background and study aims—Albuminuria, defined as an enhanced urine albumin/creatinine ratio (ACR) on a spot sample, is a validated biomarker of glomerular damage. However, it cannot always detect early renal failures in patients with type 2 diabetes (T2D), thus prompting the search for more sensitive and specific parameters. Herein, we investigated the differential role of plasma and urine neutrophil-gelatinase-associated lipocalin (NGALp,—NGALu) for the detection of diabetic kidney disease (DKD). Methods—Traditional glomerular (serum creatinine, cystatin C, ACR) damage biomarkers were evaluated in 84 patients with T2D and in 21 metabolically healthy controls. Diabetic patients were stratified into four groups based on T2D duration (less or more than 5 years) and presence and severity of DKD (early- or advanced-stage), as defined by the ACR and estimated glomerular filtration rate (eGFR). NGALp and NGALu were determined by ELISA methodology and compared among groups. Results—There was no difference in NGALp and NGALu levels between the metabolically healthy individuals and the age-matched, newly diagnosed diabetic patients in the absence of DKD. However, in contrast to NGALu, NGALp was found to be substantially increased in patients with long-standing diabetes without biochemical evidence of DKD, closely mirroring the modest, but still accelerated, decline in the eGFR typical of this chronic dysmetabolic condition, and remained overexpressed throughout the stages of DKD progression. Increased NGALu levels were, instead, rather specific in patients with biochemical evidence of DKD (i.e., marked by increased albuminuria), regardless of T2D duration. Spearman’s correlation and regression analyses showed that patient age and T2D duration could exert a strong positive impact exclusively on NGALp concentrations (ρ = 0.419, p < 0.001 for age; ρ = 0.581, p < 0.001 for T2D), and none on NGALu. Furthermore, receiver operating characteristic (ROC) analysis showed the best performance of NGALp compared to NGALu for the detection of DKD (AUC = 0.817 for NGALp, AUC = 0.711 for NGALu). Conclusions—Our data suggest a different pathophysiological and predictive role for urine and plasma NGAL in the context of T2D and DKD.

Development and internal validation of machine learning algorithms for end-stage renal disease risk prediction model of people with type 2 diabetes mellitus and diabetic kidney disease

Aims

Diabetic kidney disease (DKD) is the most common cause of end-stage renal disease (ESRD) and is associated with increased morbidity and mortality in patients with diabetes. Identification of risk factors involved in the progression of DKD to ESRD is expected to result in early detection and appropriate intervention and improve prognosis. Therefore, this study aimed to establish a risk prediction model for ESRD resulting from DKD in patients with type 2 diabetes mellitus (T2DM).

Methods

Between January 2008 and July 2019, a total of 390 Chinese patients with T2DM and DKD confirmed by percutaneous renal biopsy were enrolled and followed up for at least 1 year. Four machine learning algorithms (gradient boosting machine, support vector machine, logistic regression, and random forest (RF)) were used to identify the critical clinical and pathological features and to build a risk prediction model for ESRD.

Results

There were 158 renal outcome events (ESRD) (40.51%) during the 3-year median follow up. The RF algorithm showed the best performance at predicting progression to ESRD, showing the highest AUC (0.90) and ACC (82.65%). The RF algorithm identified five major factors: Cystatin-C, serum albumin (sAlb), hemoglobin (Hb), 24-hour urine urinary total protein, and estimated glomerular filtration rate. A nomogram according to the aforementioned five predictive factors was constructed to predict the incidence of ESRD.

Conclusion

Machine learning algorithms can efficiently predict the incident ESRD in DKD participants. Compared with the previous models, the importance of sAlb and Hb were highlighted in the current model.

Highlights

What is already known? Identification of risk factors for the progression of DKD to ESRD is expected to improve the prognosis by early detection and appropriate intervention.

What this study has found? Machine learning algorithms were used to construct a risk prediction model of ESRD in patients with T2DM and DKD. The major predictive factors were found to be CysC, sAlb, Hb, eGFR, and UTP.

What are the implications of the study? In contrast with the treatment of participants with early-phase T2DM with or without mild kidney damage, major emphasis should be placed on indicators of kidney function, nutrition, anemia, and proteinuria for participants with T2DM and advanced DKD to delay ESRD, rather than age, sex, and control of hypertension and glycemia.

Infantile Cocktail of Erythropoietin and Melatonin Restores Gait in Adult Rats with Preterm Brain Injury

Cerebral palsy (CP) is the most common cause of physical disability for children worldwide. Many infants and toddlers are not diagnosed with CP until they fail to achieve obvious motor milestones. Currently, there are no effective pharmacologic interventions available for infants and toddlers to substantially improve their trajectory of neurodevelopment. Because children with CP from preterm birth also exhibit a sustained immune system hyper-reactivity, we hypothesized that neuro-immunomodulation with a regimen of repurposed endogenous neurorestorative medications, erythropoietin (EPO) and melatonin (MLT), could improve this trajectory. Thus, we administered EPO + MLT to rats with CP during human infant-toddler equivalency to determine whether we could influence gait patterns in mature animals. After a prenatal injury on embryonic day 18 (E18) that mimics chorioamnionitis at ∼25 weeks human gestation, rat pups were born and raised with their dam. Beginning on postnatal day 15 (P15), equivalent to human infant ∼1 year, rats were randomized to receive either a regimen of EPO + MLT or vehicle (sterile saline) through P20. Gait was assessed in young adult rats at P30 using computerized digital gait analyses including videography on a treadmill. Results indicate that gait metrics of young adult rats treated with an infantile cocktail of EPO + MLT were restored compared to vehicle-treated rats (p < 0.05) and similar to sham controls. These results provide reassuring evidence that pharmacological interventions may be beneficial to infants and toddlers who are diagnosed with CP well after the traditional neonatal window of intervention.

Hypoxia-Inducible Factors and Burn-Associated Acute Kidney Injury-A New Paradigm?

O₂ deprivation induces stress in living cells linked to free-radical accumulation and oxidative stress (OS) development. Hypoxia is established when the overall oxygen pressure is less than 40 mmHg in cells or tissues. However, tissues and cells have different degrees of hypoxia. Hypoxia or low O₂ tension may be present in both physiological (during embryonic development) and pathological circumstances (ischemia, wound healing, and cancer). Meanwhile, the kidneys are major energy-consuming organs, being second only to the heart, with an increased mitochondrial content and O₂ consumption. Furthermore, hypoxia-inducible factors (HIFs) are the key players that orchestrate the mammalian response to hypoxia. HIFs adapt cells to low oxygen concentrations by regulating transcriptional programs involved in erythropoiesis, angiogenesis, and metabolism. On the other hand, one of the life-threatening complications of severe burns is acute kidney injury (AKI). The dreaded functional consequence of AKI is an acute decline in renal function. Taking all these aspects into consideration, the aim of this review is to describe the role and underline the importance of HIFs in the development of AKI in patients with severe burns, because kidney hypoxia is constant in the presence of severe burns, and HIFs are major players in the adaptative response of all tissues to hypoxia.

Prediction of the Effects of Empagliflozin on Cardiovascular and Kidney Outcomes Based on Short-Term Changes in Multiple Risk Markers

Aims: The EMPA-REG OUTCOME trial demonstrated that the sodium-glucose cotransporter-2 inhibitor (SGLT2) empagliflozin reduces the risk of cardiovascular (CV) and kidney outcomes in patients with type 2 diabetes. We previously developed the parameter response efficacy (PRE) score, which translates drug effects on multiple short-term risk markers into a predicted long-term treatment effect on clinical outcomes. The main objective of this study was to assess the accuracy of the PRE score in predicting the efficacy of empagliflozin in reducing the risk of CV and kidney outcomes. Methods: Short-term (baseline to 6-months) changes in glycated hemoglobin (HbA1c), systolic blood pressure (SBP), urinary-albumin-creatinine-ratio (UACR), hemoglobin, body weight, high-density-lipoprotein (HDL) cholesterol, low-density-lipoprotein (LDL) cholesterol, uric acid, and potassium were determined among 7020 patients with type 2 diabetes and established CV disease in the EMPA-REG OUTCOME trial. The beta-coefficients, derived from a Cox proportional hazards model in a pooled database consisting of 6355 patients with type 2 diabetes, were applied to the short-term risk markers in the EMPA-REG OUTCOME trial to predict the empagliflozin-induced impact on CV (defined as a composite of non-fatal myocardial infarction, non-fatal stroke, or CV death) and kidney (defined as a composite of doubling of serum creatinine or end-stage kidney disease) outcomes. Results: Empagliflozin compared to placebo reduced HbA1c (0.6%), SBP (4.2 mmHg), UACR (13.0%), body weight (2.1 kg), uric acid (20.4 μmol/L), and increased hemoglobin (6.6 g/L), LDL-cholesterol (0.1 mmol/L) and HDL-cholesterol (0.04 mmol/L) (all p<0.01). Integrating these effects in the PRE score resulted in a predicted relative risk reduction (RRR) for the CV outcome of 6.4% (95% CI 1.4-11.7), which was less than the observed 14.7% (95% CI 1.3-26.4%) RRR. For the kidney outcome, the PRE score predicted a RRR of 33.4% (95% CI 26.2-39.8); the observed RRR was 46.9% (95% CI 26.8-61.5). In a subgroup of 2,811 patients with UACR ≥30 mg/g at baseline, the PRE score predicted RRR was 40.8% (95% CI 31.2-49.1) vs. the observed RRR of 40.8% (95% CI 12.4-60.0) for the kidney outcome. Conclusions: Integrating multiple short-term risk marker changes in the PRE score underestimated the effect of empagliflozin on CV and kidney outcomes, suggesting that the currently used risk markers do not fully capture the effect of empagliflozin. In patients with increased albuminuria, the PRE score adequately predicted the effect of empagliflozin on kidney outcomes.

Renal Protection with SGLT2 Inhibitors: Effects in Acute and Chronic Kidney Disease

PURPOSE OF REVIEW

This review offers a critical narrative evaluation of emerging evidence that sodium-glucose co-transporter-2 (SGLT2) inhibitors exert nephroprotective effects in people with type 2 diabetes.

RECENT FINDINGS

The SGLT2 inhibitor class of glucose-lowering agents has recently shown beneficial effects to reduce the onset and progression of renal complications in people with and without diabetes. Randomised clinical trials and 'real world' observational studies, mostly involving type 2 diabetes patients, have noted that use of an SGLT2 inhibitor can slow the decline in glomerular filtration rate (GFR), reduce the onset of microalbuminuria and slow or reverse the progression of proteinuria. The nephroprotective effects of SGLT2 inhibitors are class effects observed with each of the approved agents in people with a normal or impaired GFR. These effects are also observed in non-diabetic, lean and normotensive individuals suggesting that the mechanisms extend beyond the glucose-lowering, weight-lowering and blood pressure-lowering effects that accompany their glucosuric action in diabetes patients. A key mechanism is tubuloglomerular feedback in which SGLT2 inhibitors cause more sodium to pass along the nephron: the sodium is sensed by macula cells which act via adenosine to constrict afferent glomerular arterioles, thereby protecting glomeruli by reducing intraglomerular pressure. Other effects of SGLT2 inhibitors improve tubular oxygenation and metabolism and reduce renal inflammation and fibrosis. SGLT2 inhibitors have not increased the risk of urinary tract infections or the risk of acute kidney injury. However, introduction of an SGLT2 inhibitor in patients with a very low GFR is not encouraged due to an initial dip in GFR, and it is prudent to discontinue therapy if there is an acute renal event, hypovolaemia or hypotension.

Changes in aging-induced kidney dysfunction in mice based on a metabolomics analysis

Kidney dysfunction is particularly important in systemic organ injuries caused by aging. Metabolomics are utilized in this study to explore the mechanism of kidney dysfunction during aging by the identification of metabolites and the characterization of metabolic pathways. We analyzed the serum biochemistry and kidney histopathology of male Kunming mice aged 3 months and 24 months and found that the aged mice had inflammatory lesions, aggravated fibrosis, and functional impairment. A high-resolution untargeted metabolomics analysis revealed that the endogenous metabolites in the kidneys and urine of the mice were significantly changed by 25 and 20 metabolites, respectively. A pathway analysis of these differential metabolites revealed six key signaling pathways, namely, D-glutamine and D-glutamate metabolism, purine metabolism, the citrate cycle [tricarboxylic acid (TCA) cycle], histidine metabolism, pyruvate metabolism, and glyoxylate and dicarboxylate metabolism. These pathways are involved in amino acid metabolism, carbohydrate metabolism, and nucleotide metabolism, and these can lead to immune regulation, inflammatory responses, oxidative stress damage, cellular dysfunction, and bioenergy disorders, and they are closely associated with aging and kidney insufficiency. We also screened nine types of sensitive metabolites in the urine as potential biomarkers of kidney dysfunction during the aging process to confirm their therapeutic targets in senior-induced kidney dysfunction and to improve the level of risk assessment for senile kidney injury.

Understanding the protective effects of SGLT2 inhibitors in type 2 diabetes patients with chronic kidney disease

INTRODUCTION

Sodium-glucose co-transporter type 2 inhibitors (SGLT2is) were developed as glucose-lowering agents for the management of type 2 diabetes (T2D). Unexpectedly, they showed a significant reduction in hospitalization for heart failure and hard renal outcomes in patients with and without T2D. Underlying mechanisms remain a matter of debate.

AREAS COVERED

We summarize the protective renal effects of SGLT2is in patients with cardiovascular disease, chronic kidney disease (CKD, especially with albuminuria) or heart failure; a description of the safety of SGLT2is, with a special focus on the risk/benefit balance in people with stage 3 CKD; a comprehensive discussion of mechanisms that could explain nephro-protection; a reappraisal of the positioning of SGLT2is in recent international guidelines.

EXPERT OPINION

Several mechanisms could contribute to improved renal prognosis with SGLT2is, among which a reduction in intraglomerular pressure by restoring the tubuloglomerular feedback, a diuretic effect that contributes to lower albuminuria and renal decongestion, especially if fluid overload is present, a reduction in renal oxygen consumption, an improvement of heart failure status with less cardiorenal syndrome and a lower risk of acute renal injury. All these effects may be mutually not exclusive, and their respective contribution may differ according to patient characteristics.

Clinical Evidence and Proposed Mechanisms of Sodium-Glucose Cotransporter 2 Inhibitors in Heart Failure with Preserved Ejection Fraction: A Class Effect?

Effective treatment for heart failure with preserved ejection fraction (HFpEF) is an unmet need in cardiovascular medicine. The pathophysiological drivers of HFpEF are complex, differing depending on phenotype, making a one-size-fits-all treatment approach unlikely. Remarkably, sodium-glucose cotransporter 2 inhibitors (SGLT2is) may be the first drug class to improve cardiovascular outcomes in HFpEF. Randomised controlled trials suggest a benefit in mortality, and demonstrate decreased hospitalisations and improvement in functional status. Limitations in trials exist, either due to small sample sizes, differing results between trials or decreased efficacy at higher ejection fractions. SGLT2is may provide a class effect by targeting various pathophysiological HFpEF mechanisms. Inhibition of SGLT2 and Na⁺/H⁺ exchanger 3 in the kidney promotes glycosuria, osmotic diuresis and natriuresis. The glucose deprivation activates sirtuins - protecting against oxidation and beneficially regulating metabolism. SGLT2is reduce excess epicardial adipose tissue and its deleterious adipokines. Na⁺/H⁺ exchanger 1 inhibition in the heart and lungs reduces sodium-induced calcium overload and pulmonary hypertension, respectively.

Renoprotective Role of Hypoxia-Inducible Factors and the Mechanism

BACKGROUND

The kidney requires abundant blood supply, and oxygen is transmitted by diffusion through blood vessels. Most physiological metabolism of the kidney depends on oxygen, so it is very sensitive to oxygen. An increasing pool of evidence suggests that hypoxia is involved in almost all acute and chronic kidney diseases (CKDs). Vascular damage, tubular injury, and fibrosis are the main pathologies associated during hypoxia. Hypoxia-inducible factors (HIFs) are the main mediators during hypoxia, but their functions remain controversial. This article reviewed recent studies and described its mechanisms on renoprotection.

SUMMARY

HIF is degraded rapidly during under normal oxygen. But under hypoxia, HIFs accumulate and many target genes are regulated by HIFs. Homeostasis during injury is maintained through these genes. Pretreatment of HIF can protect the kidney from acute hypoxia and can improve repair, but HIF's role in CKD and in renal tumor is still controversial. Due to its mechanism in kidney disease, many drugs toward HIFs are widely researched, even some of which have been used in clinical or in clinical research.

KEY MESSAGES

In this review, we described the known physiological mechanisms, target genes, and renal protective roles of HIFs, and we discussed several drugs that are researched due to such renal protective roles.

OUP accepted manuscript

Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent hereditary kidney disease. Recent evidence suggests that the pathogenesis of ADPKD is a complex web of abnormal cellular processes including altered cell signaling, disordered cell metabolism, impaired autophagy, increased apoptosis, mitochondrial dysfunction and chronic inflammation. Sodium–glucose cotransporter (SGLT) inhibitors (SGLTi) reduce body weight, blood pressure and blood glucose levels, have kidney and cardiovascular protective activity, and have been reported to decrease inflammation, increase autophagy and improve mitochondrial dysfunction. We now review results from preclinical studies on SGLTi for ADPKD identified through a systematic search of the MEDLINE, Cochrane Library, Embase and PubMed databases. Potential underlying mechanisms for the conflicting results reported as well as implications for clinical translation are discussed, as ADPKD patients were excluded from clinical trials exploring kidney protection by SGLT2 inhibitors (SGLT2i). However, they were not excluded from cardiovascular safety trials or trials for cardiovascular conditions. A post-hoc analysis of the kidney function trajectories and safety of SGLT2i in ADPKD patients enrolled in such trials may provide additional information. In conclusion, SGLT2i are cardio- and nephroprotective in diverse clinical situations. Currently, it is unclear whether ADPKD patients may benefit from SGLT2i in terms of kidney function preservation, and their safety in this population remains unexplored. We propose a roadmap to address this unmet clinical need.

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

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

Transcription Factor ChREBP Mediates High Glucose-Evoked Increase in HIF-1α Content in Epithelial Cells of Renal Proximal Tubules

Hyperglycemia/diabetes appears to be accompanied by the state of hypoxia, which especially affects kidneys. The aim of the study was to elucidate the mechanism of high glucose action on HIF-1α expression in renal proximal tubule epithelial cells. The research hypotheses included: (1) the participation of transcription factor ChREBP; and (2) the involvement of the effects resulting from pseudohypoxia, i.e., lowered intracellular NAD+/NADH ratio. The experiments were performed on HK-2 cells and primary cells: D-RPTEC (Diseased Human Renal Proximal Tubule Epithelial Cells—Diabetes Type II) and RPTEC (Renal Proximal Tubule Epithelial Cells). Protein and mRNA contents were determined by Western blot and RT-qPCR, respectively. ChREBP binding to DNA was detected applying chromatin immunoprecipitation, followed by RT-qPCR. Gene knockdown was performed using siRNA. Sirtuin activity and NAD⁺/NADH ratio were measured with commercially available kits. It was found that high glucose in HK-2 cells incubated under normoxic conditions: (1) activated transcription of HIF-1 target genes, elevated HIF-1α and ChREBP content, and increased the efficacy of ChREBP binding to promoter region of HIF1A gene; and (2), although it lowered NAD⁺/NADH ratio, it affected neither sirtuin activity nor HIF-1α acetylation level. The stimulatory effect of high glucose on HIF-1α expression was not observed upon the knockdown of ChREBP encoding gene. Experiments on RPTEC and D-RPTEC cells demonstrated that HIF-1α content in diabetic proximal tubular cells was lower than that in normal ones but remained high glucose-sensitive, and the latter phenomenon was mediated by ChREBP. Thus, it is concluded that the mechanism of high glucose-evoked increase in HIF-1α content in renal proximal tubule endothelial cells involves activation of ChREBP, indirectly capable of HIF1A gene up-regulation.

Safety and efficacy of dapagliflozin in patients with focal segmental glomerulosclerosis: A prespecified analysis of the DAPA-CKD trial

Background

Despite renin–angiotensin–aldosterone system blockade and immunosuppressive treatment, focal segmental glomerulosclerosis (FSGS) often progresses to kidney failure. The objective of this prespecified analysis of the dapagliflozin and prevention of adverse outcomes in chronic kidney disease trial (DAPA-CKD) was to assess efficacy and safety of dapagliflozin in a small subgroup of participants with FSGS confirmed by kidney biopsy.

Methods

In DAPA-CKD, patients with an estimated glomerular filtration rate (eGFR) 25–75 mL/min/1.73 m² and urinary albumin:creatinine ratio (UACR) 200–5000 mg/g (22.6–565 mg/mol) were randomized to dapagliflozin 10 mg once daily or placebo as an adjunct to standard care and followed for median 2.4 years. The primary composite endpoint was sustained eGFR decline ≥50%, end-stage kidney disease, or kidney or cardiovascular death. The endpoint of interest for this analysis was eGFR slope (acute effects from baseline to Week 2 and chronic effects from Week 2 to end of treatment).

Results

Of 104 participants with biopsy-confirmed FSGS, 45 were randomized to dapagliflozin and 59 to placebo. Mean (standard deviation) age was 54.0 (14.3) years, mean eGFR 41.9 (11.5) mL/min/1.73 m² and median (interquartile range) UACR 1248 (749–2211) mg/g. The primary outcome occurred in 4 (8.9%) and 7 (11.9%) participants randomized to dapagliflozin and placebo, respectively [hazard ratio 0.62, 95% confidence interval (95% CI) 0.17, 2.17]. Dapagliflozin led to a larger acute reduction (standard error) in eGFR compared with placebo (−4.5, 95% CI −5.9 to −3.1 versus −0.9, −2.1 to 0.4 mL/min/1.73 m²/2 weeks). Thereafter, mean rates of chronic eGFR decline with dapagliflozin and placebo were −1.9 (−3.0, −0.9) and −4.0 (−4.9, −3.0) mL/min/1.73 m²/year, respectively (difference 2.0, 95% CI 0.6 to 3.5, mL/min/1.73 m²/year). Adverse events leading to study drug discontinuation were similar in both groups; there were fewer serious adverse events with dapagliflozin.

Conclusions

Among DAPA-CKD participants with FSGS, dapagliflozin reduced the rate of chronic decline of eGFR compared with placebo, although this difference was not statistically significant.