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

Progress of SGLT2 inhibitors in the treatment of common immune-related nephropathies

The immune system can lead to a variety of renal diseases through direct or indirect mechanisms. In immune-mediated nephropathy, though standardized treatment, there are still a small number of patients with further decline in renal function, which may even progress to renal failure; sodium-glucose cotransporter protein 2 (SLC5A2,SGLT2) inhibitors not only can significantly reduce blood glucose, but also have an additional protective effect on the kidneys and the heart; this review concludes the potential mechanism of the renal protective effect of SGLT2i and the new advances in the recent years in common immune-mediated nephropathies, which can provide new theoretical references to optimize the therapeutic strategy of common immune-mediated nephropathies.

Integrated network pharmacology and GC-MS-based metabolomics to investigate the chemical profile and efficacy of Anemarrhenae Rhizoma and its processed products

RATIONALE

Anemarrhenae Rhizoma (AR) has been a frequently utilized traditional Chinese medicine (TCM) for an extended period, with its salt-processed variant being a prevalent application form. Contemporary pharmacological investigations have demonstrated that the salt-processed iteration exhibits a multitude of markedly augmented pharmacological properties. However, whether the pharmacodynamic material basis of this change is related to volatile substances remains unclear. The aim of this study was to develop a strategy to screen volatile pharmacodynamic substances in AR and salt-processed AR (SAR).

METHODS

A comprehensive approach was developed to identify volatile pharmacodynamic compounds by integrating plant metabolomics, target network pharmacology, and molecular docking technology. Plant metabolomics using GC-MS analysis was conducted to identify volatile chemical markers distinguishing between AR and SAR. Subsequently, network pharmacology was utilized to investigate the correlation between chemical markers and associated diseases. Following this, molecular docking technology was utilized to explore the correlation between chemical markers and disease targets, resulting in the discovery of potential quality control markers.

RESULTS

Fifty volatile compounds were isolated and identified in the salt of AR and SAR. The findings from plant metabolomics analysis demonstrated a distinct differentiation, revealing 13 volatile chemical markers that distinguish between AR and SAR. A target (PPARG) associated with diabetes was identified through target network pharmacology analysis. Thirteen volatile components were subsequently chosen as potential quality markers, taking into account their hypoglycemic activity.

CONCLUSIONS

The method developed provides a novel strategy for the identification of pharmacophores in AR and SAR, as well as establishing a foundation for the exploration of the volatile differential components and pharmacodynamics in various processed products of TCMs. Additionally, the findings of this study can serve as a theoretical framework for the development and utilization of volatile components in AR and its processed derivatives.

Metabolomics and molecular dynamics unveil the therapeutic potential of epalrestat in diabetic nephropathy

Diabetic nephropathy (DN) is one of the leading clinical causes of end-stage renal failure. The classical aldose reductase (AR) inhibitor epalrestat shows beneficial effect on renal dysfunction induced by DN, with metabolic profile and molecular mechanisms remains to be investigated further. In the current study, integrated untargeted metabolomics, network pharmacology and molecular dynamics approaches were applied to explore the therapeutic mechanisms of epalrestat against DN. Firstly, untargeted serum and urine metabolomics analysis based on UPLC-Q-TOF-MS was performed, revealed that epalrestat could regulate the metabolic disorders of amino acids metabolism, arachidonic acid metabolism, pyrimidine metabolism and citrate cycle metabolism pathways after DN. Subsequently, metabolomics-based network analysis was carried out to predict potential active targets of epalrestat, mainly involving AGE-RAGE signaling pathway, TNF signaling pathway and HIF-1 signaling pathway. Moreover, a 100 ns molecular dynamics approach was employed to validate the interactions between epalrestat and the core targets, showing that epalrestat could form remarkable tight binding with GLUT1 and NFκB than it with AR. Surface-plasmon resonance assay further verified epalrestat could bind GLUT1 and NFκB proteins specifically. Overall, integrated system network analysis not only demonstrated that epalrestat could attenuate DN induced metabolic disorders and renal injuries, but also revealed that it could interact with multi-targets to play a synergistic regulatory role in the treatment of DN.

Additional renoprotective effect of the SGLT2 inhibitor dapagliflozin in a patient with ADPKD receiving tolvaptan treatment

Autosomal dominant polycystic kidney disease (ADPKD) is a major cause of end-stage kidney disease (ESKD). Vasopressin plays a pivotal role in ADPKD progression; therefore, the selective vasopressin V2 receptor antagonist tolvaptan is used as a key drug in the management of ADPKD. On the other hand, sodium-glucose cotransporter-2 inhibitors (SGLT2i), which may possibly stimulate vasopressin secretion due to the diuretic effect of the drug, have been shown to have both renal and cardioprotective effects in various populations, including those with non-diabetic chronic kidney disease. However, the effect of SGLT2i in patients with ADPKD have not been fully elucidated. Herein, we report the case of a patient with ADPKD on tolvaptan who was administered the SGLT2i dapagliflozin. The patient was a Japanese woman diagnosed with ADPKD at age 30. Despite the treatment with tolvaptan, eGFR was gradually declined from 79.8 to 50 ml/min/1.73 m2 in almost 5 years and 10 mg of dapagliflozin was initiated in the hope of renoprotective effects. Although a small increase in vasopressin levels was observed, eGFR decline rate was moderated after dapagliflozin initiation. This case suggested an additional renoprotective effect of dapagliflozin in patient with ADPKD receiving tolvaptan. Although there is no evidence about the renal protective effect of SGLT2i in patients with ADPKD, we hereby report a case successfully treated with dapagliflozin for approximately 2 years. Further research, including clinical trials, is needed to evaluate whether SGLT2i are effective in patients with ADPKD.

Cardiorenal syndrome: evolving concepts and pediatric knowledge gaps

Cardiorenal syndrome (CRS) refers to concomitant dysfunction of both the heart and kidneys. The pathology in CRS is bidirectional. Many individuals with kidney disease will develop cardiovascular complications. Conversely, rates of acute kidney injury and chronic kidney disease are high in cardiac patients. While our understanding of CRS has greatly increased over the past 15 years, most research has occurred in adult populations. Improving cardiorenal outcomes in children and adolescents requires increased collaboration and research that spans organ systems. The purpose of this review is to discuss key features of CRS and help bring to light future opportunities for pediatric-specific research.

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.

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.

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.

Potentials of Natural Antioxidants in Reducing Inflammation and Oxidative Stress in Chronic Kidney Disease

Chronic kidney disease (CKD) presents a substantial global public health challenge, with high morbidity and mortality. CKD patients often experience dyslipidaemia and poor glycaemic control, further exacerbating inflammation and oxidative stress in the kidney. If left untreated, these metabolic symptoms can progress to end-stage renal disease, necessitating long-term dialysis or kidney transplantation. Alleviating inflammation responses has become the standard approach in CKD management. Medications such as statins, metformin, and GLP-1 agonists, initially developed for treating metabolic dysregulation, demonstrate promising renal therapeutic benefits. The rising popularity of herbal remedies and supplements, perceived as natural antioxidants, has spurred investigations into their potential efficacy. Notably, lactoferrin, Boerhaavia diffusa, Amauroderma rugosum, and Ganoderma lucidum are known for their anti-inflammatory and antioxidant properties and may support kidney function preservation. However, the mechanisms underlying the effectiveness of Western medications and herbal remedies in alleviating inflammation and oxidative stress occurring in renal dysfunction are not completely known. This review aims to provide a comprehensive overview of CKD treatment strategies and renal function preservation and critically discusses the existing literature's limitations whilst offering insight into the potential antioxidant effects of these interventions. This could provide a useful guide for future clinical trials and facilitate the development of effective treatment strategies for kidney functions.

SGLT2i treatment during AKI and its association with major adverse kidney events

Background

The association between the administration of sodium-glucose cotransporter 2 inhibitors (SGLT2is) during acute kidney injury (AKI) and the incidence of major adverse kidney events (MAKEs) is not known.

Methods

This retrospective cohort study included patients with AKI and compared the outcomes for those who were treated with SGLT2is during hospitalization and those without SGLT2i treatment. The associations of SGLT2i use with MAKEs at 10 and 30-90 days, each individual MAKE component, and the pre-specified patient subgroups were analyzed.

Results

From 2021 to 2023, 374 patients were included in the study-316 without SGLT2i use and 58 with SGLT2i use. Patients who were treated with SGLT2is were older; had a greater prevalence of diabetes, hypertension, chronic heart failure, and chronic kidney disease; required hemodialysis less often; and presented stage 3 AKI less frequently than those who were not treated with SGLT2is. Logistic regression analysis with nearest-neighbor matching revealed that SGLT2i use was not associated with the risk of MAKE10 (OR 1.08 [0.45-2.56]) or with MAKE30-90 (OR 0.76 [0.42-1.36]). For death, the stepwise approach demonstrated that SGLT2i use was associated with a reduced risk (OR 0.08; 0.01-0.64), and no effect was found for kidney replacement therapy (KRT). The subgroups of patients who experienced a reduction in the risk of MAKEs in patients with AKI treated with SGLT2is were those older than 61 years, those with an eGFR >81, and those without a history of hypertension or DM (p ≤ 0.05 for all).

Conclusion

The use of SGLT2is during AKI had no effect on short- or medium-term MAKEs, but some subgroups of patients may have experienced benefits from SGLT2i treatment.

Evaluation of renal tubular function by multiparametric functional MRI in early diabetes

Purpose To evaluate the tubular function in an alloxan-induced type 1 diabetes mellitus (DM) rabbit model measured by renal oxygenation (R2*), oxygen extraction fraction (OEF), and renal blood flow (RBF) using blood oxygenation level dependent, asymmetric spin echo, and arterial spin labeling MRI. Methods Twenty-six rabbits were randomized into the 3-day DM group (n = 13) and the 7-day DM group (n = 13). We performed pairs of multiparametric MRIs (before and after furosemide injection) at baseline and 3/7 days post-DM, and scored pathological kidney injury. We performed statistical analyses using non-parametric, chi-square, and Spearman correlation tests. Results At baseline, medullary R2* significantly decreased by 24.97% and 16.74% in the outer and inner stripes of the outer medulla (OS and IS, p = 0.006 and 0.003, respectively) after furosemide administration. While the corresponding OEF decreased by 15.91% for OS and 16.67% for IS (both p = 0.003), and no significant change in medullary RBF was observed (p > 0.05). In the 3-day DM group, the decrease of medullary R2* and OEF post-furosemide became unremarkable, suggesting tubular dysfunction. We noticed similar changes in the 7-day DM group. Correlation analysis showed pathological tubular injury score significantly correlated with medullary ∆R2* (post-furosemide - pre-furosemide difference, r = 0.82 for OS and 0.82 for IS) and ∆OEF (r = 0.82 for OS and 0.82 for IS) (p < 0.001, respectively). Conclusion: The combination of medullary OEF and R2* in response to furosemide could detect renal tubular dysfunction in early DM.

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.

Erythrocytosis and CKD: A Review

Erythrocytosis or polycythemia is defined as an increase in red blood cell concentration above the age- and sex-specific normal levels. Unlike anemia, which is very common in patients with chronic kidney disease (CKD), erythrocytosis is less frequent but requires specific understanding by health care professionals in order to provide the best care. Erythrocytosis, especially when undiagnosed and untreated, can lead to serious thrombotic events and higher mortality. Classic causes of erythrocytosis associated with CKD include cystic kidney diseases, kidney or other erythropoietin-secreting neoplasms, high-altitude renal syndrome, overdosage of erythropoietin-stimulating agents, androgen therapy, heavy smoking, chronic lung disease, obstructive sleep apnea, IgA nephropathy, post-kidney transplant erythrocytosis, renal artery stenosis, and congenital etiologies. After ruling out the common acquired causes of erythrocytosis and/or in the presence of suggestive parameters, primary erythrocytosis or polycythemia vera (PV) should be considered, and patients should be screened for JAK2V617F somatic mutation. The newest entity inducing erythrocytosis is linked to the use of sodium/glucose cotransporter 2 (SGLT2) inhibitors that hypothetically activate hypoxia-inducible factor 2α (HIF-2α) and in some cases unmask PV. This Review focuses on the pathogenesis, renal manifestations and management of PV, the pathophysiology of erythrocytosis induced by SGLT2 inhibitors and the relevance of timely JAK2 mutation screening in these patients.

Ischemia-Reperfusion Injury in Kidney Transplantation: Mechanisms and Potential Therapeutic Targets

Kidney transplantation offers a longer life expectancy and a better quality of life than dialysis to patients with end-stage kidney disease. Ischemia-reperfusion injury (IRI) is thought to be a cornerstone in delayed or reduced graft function and increases the risk of rejection by triggering the immunogenicity of the organ. IRI is an unavoidable event that happens when the blood supply is temporarily reduced and then restored to an organ. IRI is the result of several biological pathways, such as transcriptional reprogramming, apoptosis and necrosis, innate and adaptive immune responses, and endothelial dysfunction. Tubular cells mostly depend on fatty acid (FA) β-oxidation for energy production since more ATP molecules are yielded per substrate molecule than glucose oxidation. Upon ischemia-reperfusion damage, the innate and adaptive immune system activates to achieve tissue clearance and repair. Several cells, cytokines, enzymes, receptors, and ligands are known to take part in these events. The complement cascade might start even before organ procurement in deceased donors. However, additional experimental and clinical data are required to better understand the pathogenic events that take place during this complex process.

Larger Degree of Renal Function Decline in Chronic Kidney Disease Is a Favorable Factor for the Attenuation of eGFR Slope Worsening by SGLT2 Inhibitors: A Retrospective Observational Study

INTRODUCTION

Sodium-glucose cotransporter 2 inhibitors (SGLT2Is) have beneficial effects on the renal function of chronic kidney disease (CKD) patients, although the types of patients suitable for this treatment remain unclear.

METHODS

A retrospective observational study was conducted on CKD patients who were treated with SGLT2I in our department from 2020 to 2023. The estimated glomerular filtration rate (eGFR) just before treatment was defined as the baseline and the difference between pre-and post-treatment eGFR slopes were used to compare the improvement of renal function. Logistic regression analysis was used to evaluate the independent factors for its improvement.

RESULTS

A total of 128 patients were analyzed (mean age: 67.2 years; number of women: 28 [22%]). The mean eGFR was 42.1 mL/min/1.73 m2, and urine protein was 0.66 g/gCr. The eGFR slopes of patients with an eGFR <30 mL/min/1.73 m2 were improved significantly after treatment (-0.28 to -0.14 mL/min/1.73 m2/month, p < 0.001) but were worsened in patients with an eGFR ≥30 mL/min/1.73 m2. Logistic analysis for the improvement in eGFR slopes showed that women (odds ratio [OR], 5.63; 95% confidence interval [CI], 1.16-27.3; p = 0.03), use of mineralocorticoid receptor antagonists (OR, 11.79; 95% CI, 1.05-132.67; p = 0.012) and rapid decline of eGFR before treatment (OR, 12.8 per mL/min/1.73 m2/month decrease in eGFR; 95% CI, 3.32-49.40; p < 0.001) were significant independent variables.

CONCLUSION

SGLT2Is may have beneficial effects, especially for rapid decliners of eGFR, including advanced CKD.

Minireview: Understanding and targeting inflammatory, hemodynamic and injury markers for cardiorenal protection in type 1 diabetes

The coexistence of cardiovascular disease (CVD) and diabetic kidney disease (DKD) is common in people with type 1 diabetes (T1D) and is strongly associated with an increased risk of morbidity and mortality. Hence, it is imperative to explore robust tools that can accurately reflect the development and progression of cardiorenal complications. Several cardiovascular and kidney biomarkers have been identified to detect at-risk individuals with T1D. The primary aim of this review is to highlight biomarkers of injury, inflammation, or renal hemodynamic changes that may influence T1D susceptibility to CVD and DKD. We will also examine the impact of approved pharmacotherapies for type 2 diabetes, including renin-angiotensin-aldosterone system (RAAS) inhibitors, sodium-glucose cotransporter-2 (SGLT2) inhibitors and glucagon-like peptide-1 receptor agonists (GLP-1RAs) on candidate biomarkers for cardiorenal complications in people with T1D and discuss how these changes may potentially mediate kidney and cardiovascular protection. Identifying predictive and prognostic biomarkers for DKD and CVD may highlight potential drug targets to attenuate cardiorenal disease progression, implement novel risk stratification measures in clinical trials, and improve the assessment, diagnosis, and treatment of at-risk individuals with T1D.

Dapagliflozin-Induced Erythrocytosis in Chronic Kidney Disease: A Rare Occurrence

Erythrocytosis, a rare adverse effect associated with sodium-glucose cotransporter 2 inhibitors (SGLT2i), has been reported in diabetic patients, but its occurrence in those with chronic kidney disease (CKD) remains underrecognized. Here, we present two cases of dapagliflozin-related erythrocytosis in diabetic patients with CKD, highlighting the need for increased awareness among clinicians. Despite the established efficacy of SGLT2i in managing type 2 diabetes mellitus (T2DM) and its cardiovascular benefits, erythrocytosis poses a potential complication, necessitating thorough understanding and monitoring. While the precise mechanism of SGLT2i-induced erythrocytosis remains unclear, hypotheses include hemoconcentration and modulation of iron metabolism. Notably, our cases demonstrate a rapid onset of erythrocytosis, possibly exacerbated by CKD, emphasizing the importance of vigilant hemoglobin monitoring, especially in CKD patients on SGLT2i therapy. Timely discontinuation of dapagliflozin resulted in a significant reduction in hemoglobin levels, underscoring the critical role of early intervention in preventing erythrocytosis-related complications. This report advocates for routine hematological evaluation in CKD patients treated with SGLT2i to promptly detect and manage erythrocytosis, enhancing patient safety and improving clinical outcomes.

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.

Epidemiology and Management of Patients With Kidney Disease and Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) comprises approximately one-half of all diagnoses of heart failure. There is significant overlap of this clinical syndrome with chronic kidney disease (CKD), with many shared comorbid conditions. The presence of CKD in patients with HFpEF is one of the most powerful risk factors for adverse clinical outcomes, including death and heart failure hospitalization. The pathophysiology linking HFpEF and CKD remains unclear, but it is postulated to consist of numerous bidirectional pathways, including endothelial dysfunction, inflammation, obesity, insulin resistance, and impaired sodium handling. The diagnosis of HFpEF requires certain criteria to be satisfied, including signs and symptoms consistent with volume overload caused by structural or functional cardiac abnormalities and evidence of increased cardiac filling pressures. There are numerous overlapping metabolic clinical syndromes in patients with HFpEF and CKD that can serve as targets for intervention. With an increasing number of therapies available for HFpEF and CKD as well as for obesity and diabetes, improved recognition and diagnosis are paramount for appropriate management and improved clinical outcomes in patients with both HFpEF and CKD.

Dapagliflozin ameliorated retinal vascular permeability in diabetic retinopathy rats by suppressing inflammatory factors

BACKGROUND

Diabetic retinopathy is a common microvascular complication of diabetes and one of the major causes of blindness in the working-age population. Emerging evidence has elucidated that inflammation drives the key mechanism of diabetes-mediated retinal disturbance. As a new therapeutic drug targeting diabetes, whether dapagliflozin could improve vascular permeability from the perspective of anti-inflammatory effect need to be further explored.

METHODS

Type 2 diabetic retinopathy rat model was established and confirmed by fundus fluorescein angiography (FFA). ELISA detected level of plasma inflammatory factors and C-peptide. HE staining, immunohistochemistry and western blot detected histopathology changes of retina, expression of retinal inflammatory factors and tight junction proteins.

RESULTS

Dapagliflozin exhibited hypoglycemic effect comparable to insulin, but did not affect body weight. By inhibiting expression of inflammatory factors (NLRP3, Caspase-1, IL-18, NF-κB) in diabetic retina and plasma, dapagliflozin reduced damage of retinal tight junction proteins and improved retinal vascular permeability. The anti-inflammatory effect of dapagliflozin was superior to insulin.

CONCLUSIONS

Dapagliflozin improved retinal vascular permeability by reducing diabetic retinal and plasma inflammatory factors. The anti-inflammatory mechanism of dapagliflozin is independent of hypoglycemic effect and superior to insulin.

NRF2 in kidney physiology and disease

The role of NRF2 in kidney biology has received considerable interest over the past decade. NRF2 transcriptionally controls genes responsible for cellular protection against oxidative and electrophilic stress and has anti-inflammatory functions. NRF2 is expressed throughout the kidney and plays a role in salt and water handling. In disease, animal studies show that NRF2 protects against tubulointerstitial damage and reduces interstitial fibrosis and tubular atrophy, and may slow progression of polycystic kidney disease. However, the role of NRF2 in proteinuric glomerular diseases is controversial. Although the NRF2 inducer, bardoxolone methyl (CDDO-Me), increases glomerular filtration rate in humans, it has not been shown to slow disease progression in diabetic kidney disease and Alport syndrome. Furthermore, bardoxolone methyl was associated with negative effects on fluid retention, proteinuria, and blood pressure. Several animal studies replicate findings of worsened proteinuria and a more rapid progression of kidney disease, although considerable controversy exists. It is clear that further study is needed to better understand the effects of NRF2 in the kidney. This review summarizes the available data to clarify the promise and risks associated with targeting NRF2 activity in the kidney.

Hypoxia-inducible factor-2α promotes fibrosis in non-alcoholic fatty liver disease by enhancing glutamine catabolism and inhibiting yes-associated protein phosphorylation in hepatic stellate cells

Non-alcoholic fatty liver disease (NAFLD) has a high global prevalence and affects approximately one-third of adults, owing to high-fat dietary habits and a sedentary lifestyle. The role of hypoxia-inducible factor 2α (HIF-2α) in NAFLD progression remains unknown. This study aimed to investigate the effects of chronic hypoxia on NAFLD progression by examining the role of hypoxia-inducible factor 2α (HIF-2α) activation and that of hepatic stellate cell (HSC)-derived myofibroblasts through glutaminolysis. We hypothesised that hypoxia exacerbates NAFLD by promoting HIF-2α upregulation and inhibiting phosphorylated yes-associated protein (YAP), and that increasing YAP expression enhances HSC-derived myofibroblasts. We studied patients with NAFLD living at high altitudes, as well as animal models and cultured cells. The results revealed significant increases in HSC-derived myofibroblasts and collagen accumulation caused by HIF-2α and YAP upregulation, both in patients and in a mouse model for hypoxia and NAFLD. HIF-2α and HIF-2α-dependent YAP downregulation reduced HSC activation and myofibroblast levels in persistent chronic hypoxia. Furthermore, hypoxia-induced HIF-2α upregulation promoted YAP and inhibited YAP phosphorylation, leading to glutaminase 1 (GLS1), SLC38A1, α-SMA, and Collagen-1 overexpression. Additionally, hypoxia restored mitochondrial adenosine triphosphate production and reactive oxygen species (ROS) overproduction. Thus, chronic hypoxia-induced HIF-2α activation enhances fibrosis and NAFLD progression by restoring mitochondrial ROS production and glutaminase-1-induced glutaminolysis, which is mediated through the inhibition of YAP phosphorylation and increased YAP nuclear translocation. In summary, HIF-2α plays a pivotal role in NAFLD progression during chronic hypoxia.

Parallelism and non-parallelism in diabetic nephropathy and diabetic retinopathy

Diabetic nephropathy (DN) and diabetic retinopathy (DR), as microvascular complications of diabetes mellitus, are currently the leading causes of end-stage renal disease (ESRD) and blindness, respectively, in the adult working population, and they are major public health problems with social and economic burdens. The parallelism between the two in the process of occurrence and development manifests in the high overlap of disease-causing risk factors and pathogenesis, high rates of comorbidity, mutually predictive effects, and partial concordance in the clinical use of medications. However, since the two organs, the eye and the kidney, have their unique internal environment and physiological processes, each with specific influencing molecules, and the target organs have non-parallelism due to different pathological changes and responses to various influencing factors, this article provides an overview of the parallelism and non-parallelism between DN and DR to further recognize the commonalities and differences between the two diseases and provide references for early diagnosis, clinical guidance on the use of medication, and the development of new drugs.

Chapter 2: Clinical and Mechanistic Potential of Sodium-Glucose Co-Transporter 2 (SGLT2) Inhibitors in Heart Failure with Preserved Ejection Fraction

Sodium-glucose co-transporter 2 inhibitors (SGLT2i) have emerged as an important approach for the treatment of heart failure in patients with or without diabetes. Although the precise mechanisms underpinning their clinical impact remain incompletely resolved, mechanistic studies and insights from major clinical trials have demonstrated the impact of SGLT2 inhibitors on numerous cardio-renal-metabolic pathways of relevance to heart failure with preserved ejection fraction (HFpEF), which, in the contemporary era, constitutes approximately half of all patients with heart failure. Despite rates of morbidity and mortality that are commensurate with those of heart failure with reduced ejection fraction, disease-modifying therapies have comparatively been severely lacking. As such, HFpEF remains among the greatest unmet needs in cardiovascular medicine. Within the past decade, HFpEF has been established as a highly integrated disorder, involving not only the cardiovascular system, but also the lungs, kidneys, skeletal muscle, and adipose tissue. Given their multisystem impact, SGLT2i offer unique promise in addressing the complex pathophysiology of HFpEF, and in recent randomized controlled trials, were shown to significantly reduce heart failure events and cardiovascular death in patients with HFpEF. Herein, we discuss several proposed mechanisms of clinical benefit of SGLT2i in HFpEF.

Evidential support for garlic supplements against diabetic kidney disease: a preclinical meta-analysis and systematic review

Garlic (Allium sativum L.) is a popular spice that is widely used for food and medicinal purposes and has shown potential effects on diabetic kidney disease (DKD). Nevertheless, systematic preclinical studies are still lacking. In this meta-analysis and systematic review, we evaluated the role and potential mechanisms of action of garlic and its derived components in animal models of DKD. We searched eight databases for relevant studies from the establishment of the databases to December 2022 and updated in April 2023 before the completion of this review. A total of 24 trials were included in the meta-analysis. It provided preliminary evidence that supplementing with garlic could improve the indicators of renal function (BUN, Scr, 24 h urine volume, proteinuria, and KI) and metabolic disorders (BG, insulin, and body weight). Meanwhile, the beneficial effects of garlic and its components in DKD could be related to alleviating oxidative stress, suppressing inflammatory reactions, delaying renal fibrosis, and improving glucose metabolism. Furthermore, time-dose interval analysis exhibited relatively greater effectiveness when garlic products were supplied at doses of 500 mg kg-1 with interventions lasting 8-10 weeks, and garlic components were administered at doses of 45-150 mg kg-1 with interventions lasting 4-10 weeks. This meta-analysis and systematic review highlights for the first time the therapeutic potential of garlic supplementation in animal models of DKD and offers a more thorough evaluation of its effects and mechanisms to establish an evidence-based basis for designing future clinical trials.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

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

Background and aims

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

Methods

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

Results

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

Conclusion

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

Hypoxia-induced signaling in the cardiovascular system: pathogenesis and therapeutic targets

Hypoxia, characterized by reduced oxygen concentration, is a significant stressor that affects the survival of aerobic species and plays a prominent role in cardiovascular diseases. From the research history and milestone events related to hypoxia in cardiovascular development and diseases, The "hypoxia-inducible factors (HIFs) switch" can be observed from both temporal and spatial perspectives, encompassing the occurrence and progression of hypoxia (gradual decline in oxygen concentration), the acute and chronic manifestations of hypoxia, and the geographical characteristics of hypoxia (natural selection at high altitudes). Furthermore, hypoxia signaling pathways are associated with natural rhythms, such as diurnal and hibernation processes. In addition to innate factors and natural selection, it has been found that epigenetics, as a postnatal factor, profoundly influences the hypoxic response and progression within the cardiovascular system. Within this intricate process, interactions between different tissues and organs within the cardiovascular system and other systems in the context of hypoxia signaling pathways have been established. Thus, it is the time to summarize and to construct a multi-level regulatory framework of hypoxia signaling and mechanisms in cardiovascular diseases for developing more therapeutic targets and make reasonable advancements in clinical research, including FDA-approved drugs and ongoing clinical trials, to guide future clinical practice in the field of hypoxia signaling in cardiovascular diseases.

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.

Modeling the renoprotective mechanisms of SGLT2 inhibition in hypertensive chronic kidney disease

Sodium-glucose cotransporter (SGLT)-2 inhibitors have recently been approved for chronic kidney disease (CKD) based on their ability to lower proteinuria and slow CKD progression independent of diabetes status. In diabetic renal disease, modulation of tubuloglomerular feedback (TGF) leading to lower intraglomerular pressure has been postulated as one of the mechanisms of renal protection with SGLT2 inhibition; however, this mechanism has not been sufficiently explored in non-diabetic CKD. We hypothesized that SGLT2 inhibition exerts renoprotection in CKD through increasing TGF despite normoglycemia. To test this hypothesis, we used an integrative mathematical model of human physiology, HumMod. Stage 3 CKD conditions were simulated by reducing nephron mass which was associated with hypertension, low glomerular filtration rate (GFR) (55 mL/min), hyperfiltration of remnant nephrons, elevated albuminuria (500 mg/day), and minimal levels of urinary glucose (0.02 mmol/L). SGLT2 inhibition was associated with acute reductions in GFR associated with afferent arteriolar vasoconstriction due to TGF. After 12 months, glomerular pressure, nephron damage, and chronic GFR decline were reduced with SGLT2 inhibition with additional SGLT1 inhibitory effects further enhancing these effects. This model supports the use of SGLT2 inhibitors to reduce hyperfiltration in CKD and mitigate renal disease progression, even in the absence of diabetes.

Overall and inter-individual effect of four different drug classes on soluble urokinase plasminogen activator receptor in type 1 and type 2 diabetes

AIM

To evaluate the effect of four different drug classes on soluble urokinase plasminogen activator receptor (suPAR), a biomarker active in multiple inflammatory processes and a risk factor for complications, in people with type 1 and type 2 diabetes.

METHODS

We conducted post hoc analyses of a randomized, open-label, crossover trial including 26 adults with type 1 and 40 with type 2 diabetes with urinary albumin-creatinine ratio ≥30 and ≤500 mg/g assigned to 4-week treatments with telmisartan 80 mg, empagliflozin 10 mg, linagliptin 5 mg and baricitinib 2 mg, separated by 4-week washouts. Plasma suPAR was measured before and after each treatment. SuPAR change after each treatment was calculated and, for each individual, the best suPAR-reducing drug was identified. Subsequently, the effect of the best individual drug was compared against the mean of the other three drugs. Repeated-measures linear mixed-effects models were employed.

RESULTS

The baseline median (interquartile range) plasma suPAR was 3.5 (2.9, 4.3) ng/mL. No overall effect on suPAR levels was observed for any one drug. The individual best-performing drug varied, with baricitinib being selected for 20 participants (30%), followed by empagliflozin for 19 (29%), linagliptin for 16 (24%) and telmisartan for 11 (17%). The individual best-performing drug reduced suPAR by 13.3% (95% confidence interval [CI] 3.7, 22.8; P = 0.007). The difference in suPAR response between the individual best-performing drug and the other three was -19.7% (95% CI -23.1, -16.3; P < 0.001).

CONCLUSIONS

We demonstrated no overall effect of 4-week treatment with telmisartan, empagliflozin, linagliptin or baricitinib on suPAR. However, individualization of treatment might significantly reduce suPAR levels.

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.

MRI Assessment of Renal Lipid Deposition and Abnormal Oxygen Metabolism of Type 2 diabetes Mellitus Based on mDixon-Quant

BACKGROUND

Diabetic nephropathy (DN) is the main cause of end-stage renal failure. Multiecho Dixon-based imaging utilizes chemical shift for water-fat separation that may be valuable in detecting changes both fat and oxygen content of the kidney from a single dataset.

PURPOSE

To investigate whether multiecho Dixon-based imaging can assess fat and oxygen metabolism of the kidney in a single breath-hold acquisition for patients with type 2 diabetes mellitus (DM).

STUDY TYPE

Prospective.

SUBJECTS

A total of 40 DM patients with laboratory examination of biochemical parameters and 20 age- and body mass index (BMI)-matched healthy volunteers (controls).

FIELD STRENGTH/SEQUENCE

3D multiecho Dixon gradient-echo sequence at 3.0 T.

ASSESSMENT

The DM patients were divided into two groups based on urine albumin-to-creatinine ratio (ACR): type 2 diabetes mellitus (DM, 20 patients, ACR < 30 mg/g) and diabetic nephropathy (DN, 20 patients, ACR ≥ 30 mg/g). In all subjects, fat fraction (FF) and relaxation rate (R2*) maps were derived from the Dixon-based imaging dataset, and mean values in manually drawn regions of interest in the cortex and medulla compared among groups. Associations between MRI and biochemical parameters, including β2-microglobulin, were investigated.

STATISTICAL TESTS

Kruskal-Wallis tests, Spearman correlation analysis, and receiver operating characteristic (ROC) curve analysis.

RESULTS

FF and R2* values of the renal cortex and medulla were significantly different among the three groups with control group < DM < DN (FF: control, 1.11± 0.30, 1.10 ± 0.39; DM, 1.52 ± 0.32, 1.57 ± 0.35; DN, 1.99 ± 0.66, 2.21 ± 0.59. R2*: Control, 16.88 ± 0.77, 20.70 ± 0.86; DM, 17.94 ± 0.75, 22.10 ± 1.12; DN, 19.20 ± 1.24, 23.63 ± 1.33). The highest correlation between MRI and biochemical parameters was that between cortex R2* and β2-microglobulin (r = 0.674). A medulla R2* cutoff of 21.41 seconds-1 resulted in a sensitivity of 80%, a specificity of 85% and achieved the largest area under the ROC curve (AUC) of 0.83 for discriminating DM from the controls. A cortex FF of 1.81% resulted in a sensitivity of 80%, a specificity of 100% and achieved the largest AUC of 0.83 for discriminating DM from DN.

DATA CONCLUSION

Multiecho Dixon-based imaging is feasible for noninvasively distinguishing DN, DM and healthy controls by measuring FF and R2* values.

EVIDENCE LEVEL

2.

TECHNICAL EFFICACY

Stage 2.

Patients with type 1 diabetes and albuminuria have a reduced brain glycolytic capability that is correlated with brain atrophy

Introduction

Patients with type 1 diabetes (T1D) demonstrate brain alterations, including white matter lesions and cerebral atrophy. In this case-control study, we investigated if a reason for this atrophy could be because of diabetes-related complications affecting cerebrovascular or cerebral glycolytic functions. Cerebral physiological dysfunction can lead to energy deficiencies and, consequently, neurodegeneration.

Methods

We examined 33 patients with T1D [18 females, mean age: 50.8 years (range: 26-72)] and 19 matched healthy controls [7 females, mean age: 45.0 years (range: 24-64)]. Eleven (33%) of the patients had albuminuria. Total brain volume, brain parenchymal fraction, gray matter volume and white matter volume were measured by anatomical MRI. Cerebral vascular and glycolytic functions were investigated by measuring global cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2) and cerebral lactate concentration in response to the inhalation of hypoxic air (12-14% fractional oxygen) using phase-contrast MRI and magnetic resonance spectroscopy (MRS) techniques. The inspiration of hypoxic air challenges both cerebrovascular and cerebral glycolytic physiology, and an impaired response will reveal a physiologic dysfunction.

Results

Patients with T1D and albuminuria had lower total brain volume, brain parenchymal fraction, and gray matter volume than healthy controls and patients without albuminuria. The inhalation of hypoxic air increased CBF and lactate in all groups. Patients with albuminuria had a significantly (p = 0.032) lower lactate response compared to healthy controls. The CBF response was lower in patients with albuminuria compared to healthy controls, however not significantly (p = 0.24) different. CMRO2 was unaffected by the hypoxic challenge in all groups (p > 0.16). A low lactate response was associated with brain atrophy, characterized by reduced total brain volume (p = 0.003) and reduced gray matter volume (p = 0.013).

Discussion

We observed a reduced response of the lactate concentration as an indication of impaired glycolytic activity, which correlated with brain atrophy. Inadequacies in upregulating cerebral glycolytic activity, perhaps from reduced glucose transporters in the brain or hypoxia-inducible factor 1 pathway dysfunction, could be a complication in diabetes contributing to the development of neurodegeneration and declining brain health.

Mediators between canagliflozin and renoprotection vary depending on patient characteristics: Insights from the CREDENCE trial

AIM

To identify the mediators between canagliflozin and renoprotection in patients with type 2 diabetes at a high risk of end-stage kidney disease (ESKD).

METHODS

In this post hoc analysis of the CREDENCE trial, the effect of canagliflozin on potential mediators (42 biomarkers) at 52 weeks and the association between changes in mediators and renal outcomes were evaluated using mixed-effects and Cox models, respectively. The renal outcome was a composite of ESKD, serum creatinine doubling or renal death. The percentage of the mediating effect of each significant mediator was calculated based on changes in the hazard ratios of canagliflozin after additional adjustment of the mediator.

RESULTS

Changes in haematocrit, haemoglobin, red blood cell (RBC) count and urinary albumin-to-creatinine ratio (UACR) at 52 weeks significantly mediated 47%, 41%, 40% and 29% risk reduction with canagliflozin, respectively. Further, 85% mediation was attributed to the combined effect of haematocrit and UACR. A large variation in mediating effects by haematocrit change existed among the subgroups, ranging from 17% in those patients with a UACR of more than 3000 mg/g to 63% in patients with a UACR of 3000 mg/g or less. In the subgroups with a UACR of more than 3000 mg/g, UACR change was the highest mediating factor (37%), driven by the strong association between UACR decline and renal risk reduction.

CONCLUSIONS

The renoprotective effects of canagliflozin in patients at a high risk of ESKD can be significantly explained by changes in RBC variables and UACR. The complementary mediating effects of RBC variables and UACR may support the renoprotective effect of canagliflozin in different patient groups.

Role of Sodium-Glucose Co-Transporter 2 Inhibitors in Chronic Kidney Disease, Congestive Heart Failure and Stroke-A Review and Clinical Guide for Healthcare Professionals

Diabetic kidney disease (DKD) causes a progressive decline in renal function, leading to end-stage kidney disease (ESKD), and increases the likelihood of cardiovascular events and mortality. The recent introduction of the sodium-glucose co-transporter 2 (SGLT-2) inhibitor has been a game changer in managing chronic kidney disease (CKD) and congestive heart failure (CHF). These agents not only slow down the progression of kidney disease but also have cardioprotective benefits, including for patients with congestive heart failure and atherosclerotic cardiovascular disease. Some evidence suggests that they can decrease the risk of stroke as well. This review aims to provide a comprehensive overview of the role of SGLT-2 inhibitors in CKD and CHF and their efficacy in stroke prevention. This review includes a comparison with glucagon-like peptide-1 (GLP-1) agonist and finerenone; focuses on safety data, the potential benefits beyond glycemic control, and a review of significant trials; and provides guidance in clinical practice.

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.

Renal intrinsic cells remodeling in diabetic kidney disease and the regulatory effects of SGLT2 Inhibitors

Diabetic kidney disease (DKD) is a prevalent complication of diabetes and a major secondary factor leading to end-stage renal disease. The kidney, a vital organ, is composed of a heterogeneous group of intrinsic cells, including glomerular endothelial cells, podocytes, mesangial cells, tubular epithelial cells, and interstitial fibroblasts. In the context of DKD, hyperglycemia elicits direct or indirect injury to these intrinsic cells, leading to their structural and functional changes, such as cell proliferation, apoptosis, and transdifferentiation. The dynamic remodeling of intrinsic cells represents an adaptive response to stimulus during the pathogenesis of diabetic kidney disease. However, the persistent stimulus may trigger an irreversible remodeling, leading to fibrosis and functional deterioration of the kidney. Sodium-glucose cotransporter 2 (SGLT2) inhibitors, a new class of hypoglycemic drugs, exhibit efficacy in reducing blood glucose levels by curtailing renal tubular glucose reabsorption. Furthermore, SGLT2 inhibitors have been shown to modulate intrinsic cell remodeling in the kidney, ameliorate kidney structure and function, and decelerate DKD progression. This review will elaborate on the intrinsic cell remodeling in DKD and the underlying mechanism of SGLT2 inhibitors in modulating it from the perspective of the renal intrinsic cell, providing insights into the pathogenesis of DKD and the renal protective action of SGLT2 inhibitors.

Fetal Reprogramming of Nutrient Surplus Signaling, O-GlcNAcylation, and the Evolution of CKD

ABSTRACT

Fetal kidney development is characterized by increased uptake of glucose, ATP production by glycolysis, and upregulation of mammalian target of rapamycin (mTOR) and hypoxia-inducible factor-1 alpha (HIF-1 α ), which (acting in concert) promote nephrogenesis in a hypoxic low-tubular-workload environment. By contrast, the healthy adult kidney is characterized by upregulation of sirtuin-1 and adenosine monophosphate-activated protein kinase, which enhances ATP production through fatty acid oxidation to fulfill the needs of a normoxic high-tubular-workload environment. During stress or injury, the kidney reverts to a fetal signaling program, which is adaptive in the short term, but is deleterious if sustained for prolonged periods when both oxygen tension and tubular workload are heightened. Prolonged increases in glucose uptake in glomerular and proximal tubular cells lead to enhanced flux through the hexosamine biosynthesis pathway; its end product-uridine diphosphate N -acetylglucosamine-drives the rapid and reversible O-GlcNAcylation of thousands of intracellular proteins, typically those that are not membrane-bound or secreted. Both O-GlcNAcylation and phosphorylation act at serine/threonine residues, but whereas phosphorylation is regulated by hundreds of specific kinases and phosphatases, O-GlcNAcylation is regulated only by O-GlcNAc transferase and O-GlcNAcase, which adds or removes N-acetylglucosamine, respectively, from target proteins. Diabetic and nondiabetic CKD is characterized by fetal reprogramming (with upregulation of mTOR and HIF-1 α ) and increased O-GlcNAcylation, both experimentally and clinically. Augmentation of O-GlcNAcylation in the adult kidney enhances oxidative stress, cell cycle entry, apoptosis, and activation of proinflammatory and profibrotic pathways, and it inhibits megalin-mediated albumin endocytosis in glomerular mesangial and proximal tubular cells-effects that can be aggravated and attenuated by augmentation and muting of O-GlcNAcylation, respectively. In addition, drugs with known nephroprotective effects-angiotensin receptor blockers, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter 2 inhibitors-are accompanied by diminished O-GlcNAcylation in the kidney, although the role of such suppression in mediating their benefits has not been explored. The available evidence supports further work on the role of uridine diphosphate N -acetylglucosamine as a critical nutrient surplus sensor (acting in concert with upregulated mTOR and HIF-1 α signaling) in the development of diabetic and nondiabetic CKD.

Hypoxia-induced PPFIA4 accelerates the progression of ovarian cancer through glucose metabolic reprogramming

Dysregulated glycolysis promotes growth and metastasis, which is one of the metabolic characteristics of ovarian cancer. Based on bioinformatics analysis, liprin-alpha-4 (PPFIA4) is a gene associated with hypoxia, and we aimed to investigate the potential mechanism of PPFIA4 during the reprogramming of glucose metabolism in ovarian cancer cells. Currently, the cell viability of ovarian cancer cells under the hypoxia treatment was evaluated by CCK-8 assay, and cell migration and invasion were measured by transwell assay and western blot. The effects of hypoxia treatment on glucose uptake, lactate production, extracellular acidification rate (ECAR), adenosine triphosphate (ATP), reactive oxygen species (ROS), Nicotinamide adenine dinucleotide phosphate (NADPH) and its oxidized form NADP + , and oxygen consumption rate (OCR) in ovarian cancer cells were examined. Then PPFIA4 was identified through bioinformatic analysis, and the regulatory effects of PPFIA4 on glucose metabolic reprogramming. Our data suggested that hypoxia enhanced the migration and invasion ability of ovarian cancer cells in vitro, and promoted the glucose metabolic reprogramming of ovarian cancer cells. Ovarian cancer cell viability, migration, and invasion were inhibited after PPFIA4 knockdown. Inhibition of PPFIA4 inhibited hypoxic-induced glucose metabolic reprogramming in ovarian cancer cells. In addition, PPFIA4 was found to bind to hypoxia-inducible factor 1alpha (HIF1A), and HIF1A prominently induced PPFIA4 expression. Collectively, HIF1A mediated upregulation of PPFIA4 and promoted reprogramming of glucose metabolism in ovarian cancer cells. Therefore, PPFIA4 may be a therapeutic target for ovarian cancer intervention.

The effect of Dipeptidyl peptidase 4 (DPP-4) inhibitors on hemoglobin level in diabetic kidney disease: A retrospective cohort study

Anemia typically develops early in the course of diabetic kidney disease (DKD). There are data to show that dipeptidyl-peptidase-4 (DPP-4) inhibitors affect hematopoietic growth factor activity and hemoglobin level. We retrospectively reviewed 443 DKD patients who were started on DDP-4 inhibitor therapy in 2019. Their hemoglobin level at baseline (6-12 months before treatment), pretreatment (0-6 months before treatment), and post-treatment periods (within 6 months after DPP-4 inhibitor), concomitant estimated glomerular filtration rate (eGFR), HbA1c, peripheral blood white cell and platelet counts were reviewed. The severity of kidney failure was classified according to the Kidney Disease: Improving Global Outcomes stages. The hemoglobin level had a small but significant decline from 11.98 ± 2.07 to 11.87 ± 2.12 g/dL from pretreatment to post-treatment period (paired Student t test, P < .0001). From the pre- to post-treatment period, the decline of hemoglobin level was 0.10 ± 0.89 g/dL, which was significantly less than that from baseline to pretreatment period (0.24 ± 0.90 g/dL, P = .0008). The change in hemoglobin level had a positive correlation with the change in HbA1c level (R = 0.218, P < .0001), but did not correlate with the type of DPP-4 inhibitor or pretreatment eGFR. There was no significant change in peripheral blood white cell or platelet count during the same period. DPP-4 inhibitor ameliorates hemoglobin decline in DKD. The effect of DPP-4 inhibitor on hemoglobin is statistically significant but clinically modest, and did not correlate with the concomitant change in kidney function.

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.

The epidemiology of ketosis and low bicarbonate concentration in inpatients treated with sodium-glucose linked cotransporter inhibitors or dipeptidyl peptidase-4 inhibitors

AIMS

To compare the level of ketones and bicarbonate in inpatients treated with sodium-glucose linked cotransporter 2 inhibitors (SGLT2i) and those treated with dipeptidyl peptidase-4 inhibitors (DPP4i).

METHODS

We conducted an electronic medical records-based cohort study. We identified patients with type 2 diabetes, with ketone measurements available, who received SGLT2i (n = 82) or DPP4i (n = 308) during admission. We compared ketone levels between those who received SGLT2i or DPP4i using mixed ordinal logistic regression. The primary outcome was level of ketosis (<0.6, 0.6-1.5, 1.6-3.0, >3 mmol/L). Secondary outcomes included bicarbonate levels, hospital complications, ICU admission, and death.

RESULTS

SGLT2i use was not associated with greater ketosis than DPP4i use, after adjusting for age, weight, Charlson Comorbidity Index, HbA1c, estimated glomerular filtration rate, principal diagnosis category, admission type and insulin administration (OR 4.52 95 % CI (0.33, 61.82)). After adjustment, there was no difference in complications (p = 0.14), ICU admissions (p = 0.64), mortality (p = 0.30), or bicarbonate levels (p = 0.97).

CONCLUSION

Ketone levels were not greater in patients who received SGLT2i than those who received DPP4i. There were no differences in bicarbonate levels, complications, ICU admissions, or mortality, implying that, in inpatients, SGLT2i use is neither associated with ketosis nor adverse clinical outcomes.

Chorioamnionitis disrupts erythropoietin and melatonin homeostasis through the placental-fetal-brain axis during critical developmental periods

Introduction: Novel therapeutics are emerging to mitigate damage from perinatal brain injury (PBI). Few newborns with PBI suffer from a singular etiology. Most experience cumulative insults from prenatal inflammation, genetic and epigenetic vulnerability, toxins (opioids, other drug exposures, environmental exposure), hypoxia-ischemia, and postnatal stressors such as sepsis and seizures. Accordingly, tailoring of emerging therapeutic regimens with endogenous repair or neuro-immunomodulatory agents for individuals requires a more precise understanding of ligand, receptor-, and non-receptor-mediated regulation of essential developmental hormones. Given the recent clinical focus on neurorepair for PBI, we hypothesized that there would be injury-induced changes in erythropoietin (EPO), erythropoietin receptor (EPOR), melatonin receptor (MLTR), NAD-dependent deacetylase sirtuin-1 (SIRT1) signaling, and hypoxia inducible factors (HIF1α, HIF2α). Specifically, we predicted that EPO, EPOR, MLTR1, SIRT1, HIF1α and HIF2α alterations after chorioamnionitis (CHORIO) would reflect relative changes observed in human preterm infants. Similarly, we expected unique developmental regulation after injury that would reveal potential clues to mechanisms and timing of inflammatory and oxidative injury after CHORIO that could inform future therapeutic development to treat PBI. Methods: To induce CHORIO, a laparotomy was performed on embryonic day 18 (E18) in rats with transient uterine artery occlusion plus intra-amniotic injection of lipopolysaccharide (LPS). Placentae and fetal brains were collected at 24 h. Brains were also collected on postnatal day 2 (P2), P7, and P21. EPO, EPOR, MLTR1, SIRT1, HIF1α and HIF2α levels were quantified using a clinical electrochemiluminescent biomarker platform, qPCR, and/or RNAscope. MLT levels were quantified with liquid chromatography mass spectrometry. Results: Examination of EPO, EPOR, and MLTR1 at 24 h showed that while placental levels of EPO and MLTR1 mRNA were decreased acutely after CHORIO, cerebral levels of EPO, EPOR and MLTR1 mRNA were increased compared to control. Notably, CHORIO brains at P2 were SIRT1 mRNA deficient with increased HIF1α and HIF2α despite normalized levels of EPO, EPOR and MLTR1, and in the presence of elevated serum EPO levels. Uniquely, brain levels of EPO, EPOR and MLTR1 shifted at P7 and P21, with prominent CHORIO-induced changes in mRNA expression. Reductions at P21 were concomitant with increased serum EPO levels in CHORIO rats compared to controls and variable MLT levels. Discussion: These data reveal that commensurate with robust inflammation through the maternal placental-fetal axis, CHORIO impacts EPO, MLT, SIRT1, and HIF signal transduction defined by dynamic changes in EPO, EPOR, MLTR1, SIRT1, HIF1α and HIF2α mRNA, and EPO protein. Notably, ligand-receptor mismatch, tissue compartment differential regulation, and non-receptor-mediated signaling highlight the importance, complexity and nuance of neural and immune cell development and provide essential clues to mechanisms of injury in PBI. As the placenta, immune cells, and neural cells share many common, developmentally regulated signal transduction pathways, further studies are needed to clarify the perinatal dynamics of EPO and MLT signaling and to capitalize on therapies that target endogenous neurorepair mechanisms.

Long-term observation of estimated fluid volume reduction after the initiation of ipragliflozin in patients with type 2 diabetes mellitus: a sub-analysis from a randomized controlled trial (PROTECT)

BACKGROUNDS/AIM

Recent studies have shown that the addition of sodium-glucose co-transporter 2 (SGLT2) inhibitors gradually reduces the estimated fluid volume parameters in a broad range of patient populations, suggesting that this mediates the clinical benefits of SGLT2 inhibitors in preventing heart failure. Here, we sought to examine the long-term (24 months) effect of the SGLT2 inhibitor ipragliflozin on the estimated fluid volume parameters in patients with type 2 diabetes mellitus (T2DM).

METHODS

In this prespecified sub-analysis of the PROTECT (Prevention of Atherosclerosis by SGLT2 Inhibitor: Multicenter, Randomized Controlled Study) trial, which was an investigator-initiated, multicenter, prospective, randomized, open-label, clinical trial primarily designed to evaluate the effect of ipragliflozin treatment administered for 24 months on carotid atherosclerosis in patients with T2DM, we evaluated serial changes in estimated plasma volume (ePV, %) calculated using the Straus formula and estimated extracellular volume (eEV, mL) calculated by the body surface area by 24 months following the initiation of 50-mg ipragliflozin once daily and compared them with those following standard care for T2DM (non-SGLT2 inhibitor use).

RESULTS

This sub-analysis included 464 patients (ipragliflozin, n = 232; control, n = 232), a full analysis set of the PROTECT trial. In an analysis using mixed-effects models for repeated measures, relative to the control group, ipragliflozin significantly reduced ePV by - 10.29% (95% confidence interval [CI]  - 12.47% to - 8.11%; P < 0.001) at 12 months and - 10.76% (95% CI - 12.86% to - 8.67%; P < 0.001) at 24 months. Additionally, ipragliflozin significantly reduced eEV by - 190.44 mL (95% CI - 249.09 to - 131.79 mL; P < 0.001) at 12 months and - 176.90 mL (95% CI  - 233.36 to - 120.44 mL; P < 0.001) at 24 months. The effects of ipragliflozin on these parameters over 24 months were mostly consistent across various patient clinical characteristics.

CONCLUSIONS

This prespecified sub-analysis from the PROTECT trial demonstrated that ipragliflozin treatment, compared with the standard care for T2DM, reduced two types of estimated fluid volume parameters in patients with T2DM, and the effect was maintained for 24 months. Our findings suggest that SGLT2 inhibitor treatment regulates clinical parameters incorporated into the calculating formulas analyzed and consequently fluid volume status for the long-term, and this may be at least partly associated with clinical benefits from chronic use of SGLT2 inhibitors. Trial registration Japan Registry of Clinical Trials, ID jRCT1071220089.

SGLT2 inhibitors: an evidence-based update on cardiovascular implications

INTRODUCTION

Sodium Glucose co-Transporter 2 (SGLT2) inhibitors (also known as 'gliflozins') represent a cornerstone to treat diabetes mellitus. Moreover, recent randomized clinical trials have demonstrated important cardioprotective effects of gliflozins, independent of the presence of diabetes. Herein, we summarize the recent therapeutic progress in the cardiovascular field obtained with SGLT2 inhibitors.

AREA COVERED

We critically examine the rationale and results of recent clinical studies examining the effects of SGLT2 inhibitors on cardiovascular outcomes, along with a brief overview of the main ongoing trials that have been designed in order to answer the many pending questions in the field of gliflozins and cardiovascular disease.

EXPERT OPINION

The favorable results of several clinical trials have broadened the therapeutic scenario for SGLT2 inhibitors, opening, at the same time, new challenges. Additionally, recent preclinical findings have evidenced off-target effects of SGLT2 inhibitors.

Finerenone: Questions and Answers-The Four Fundamental Arguments on the New-Born Promising Non-Steroidal Mineralocorticoid Receptor Antagonist

Chronic kidney disease (CKD) is one of the most common complications of diabetes mellitus and an independent risk factor for cardiovascular disease. Despite guideline-directed therapy of CKD in patients with type 2 diabetes, the risk of renal failure and cardiovascular events still remains high, and diabetes remains the leading cause of end-stage kidney disease in affected patients. To date, current medications for CKD and type 2 diabetes mellitus have not reset residual risk in patients due to a high grade of inflammation and fibrosis contributing to kidney and heart disease. This question-and-answer-based review will discuss the pharmacological and clinical differences between finerenone and other mineralocorticoid receptor antagonists and then move on to the main evidence in the cardiovascular and renal fields, closing, finally, on the potential role of therapeutic combination with sodium-glucose cotransporter 2 inhibitors (SGLT2is).

Pharmacological management of youth with type 2 diabetes and diabetic kidney disease: a comprehensive review of current treatments and future directions

INTRODUCTION

Diabetic kidney disease (DKD) is a leading cause of mortality in people with type 2 diabetes (T2D), and over 50% of individuals with youth-onset T2D will develop DKD as a young adult. Diagnosis of early-onset DKD remains a challenge in young persons with T2D secondary to a lack of available biomarkers for early DKD, while the injuries may still be reversible. Furthermore, multiple barriers exist to initiate timely prevention and treatment strategies for DKD, including a lack of Food and Drug Administration approval of medications in pediatrics; provider comfort with medication prescription, titration, and monitoring; and medication adherence.

AREAS COVERED

Therapies that have promise for slowing DKD progression in youth with T2D include metformin, renin-angiotensin-aldosterone system inhibitors, glucagon-like peptide-1 receptor agonists, sodium glucose co-transporter 2 inhibitors, thiazolidinediones, sulfonylureas, endothelin receptor agonists, and mineralocorticoid antagonists. Novel agents are also in development to act synergistically on the kidneys with the aforementioned medications. We comprehensively review the available pharmacologic strategies for DKD in youth-onset T2D including mechanisms of action, potential adverse effects, and kidney-specific effects, with an emphasis on published pediatric and adult trials.

EXPERT OPINION

Large clinical trials evaluating pharmacologic interventions targeting the treatment of DKD in youth-onset T2D are strongly needed.

Non-Haemodynamic Mechanisms Underlying Hypertension-Associated Damage in Target Kidney Components

Arterial hypertension (AH) is a global challenge that greatly impacts cardiovascular morbidity and mortality worldwide. AH is a major risk factor for the development and progression of kidney disease. Several antihypertensive treatment options are already available to counteract the progression of kidney disease. Despite the implementation of the clinical use of renin-angiotensin aldosterone system (RAAS) inhibitors, gliflozins, endothelin receptor antagonists, and their combination, the kidney damage associated with AH is far from being resolved. Fortunately, recent studies on the molecular mechanisms of AH-induced kidney damage have identified novel potential therapeutic targets. Several pathophysiologic pathways have been shown to play a key role in AH-induced kidney damage, including inappropriate tissue activation of the RAAS and immunity system, leading to oxidative stress and inflammation. Moreover, the intracellular effects of increased uric acid and cell phenotype transition showed their link with changes in kidney structure in the early phase of AH. Emerging therapies targeting novel disease mechanisms could provide powerful approaches for hypertensive nephropathy management in the future. In this review, we would like to focus on the interactions of pathways linking the molecular consequences of AH to kidney damage, suggesting how old and new therapies could aim to protect the kidney.

Intravenous injection of human umbilical cord-derived mesenchymal stem cells ameliorates not only blood glucose but also nephrotic complication of diabetic rats through autophagy-mediated anti-senescent mechanism

BACKGROUND

Diabetic nephropathy (DN) is one of the most severe complications of diabetes mellitus, which is characterized by early occurrence of albuminuria and end-stage glomerulosclerosis. Senescence and autophagy of podocytes play an important role in DN development. Human umbilical cord-derived mesenchymal stem cells (hucMSCs) have potential in the treatment of diabetes and its complications. However, the role of hucMSCs in the treatment of DN and the underlying mechanism remain unclear.

METHODS

In vivo, a streptozotocin-induced diabetic male Sprague Dawley rat model was established to determine the renoprotective effect of hucMSCs on DN by biochemical analysis, histopathology, and immunohistochemical staining of renal tissues. And the distribution of hucMSCs in various organs in rats within 168 h was analyzed. In vitro, CCK8 assay, wound healing assay, and β-galactosidase staining were conducted to detect the beneficial effects of hucMSCs on high glucose-induced rat podocytes. Real-time PCR and western blot assays were applied to explore the mechanism of action of hucMSCs.

RESULTS

The in vivo data revealed that hucMSCs were distributed into kidneys and significantly protected kidneys from diabetic damage. The in vitro data indicated that hucMSCs improved cell viability, wound healing, senescence of the high glucose-damaged rat podocytes through a paracrine action mode. Besides, the altered expressions of senescence-associated genes (p16, p53, and p21) and autophagy-associated genes (Beclin-1, p62, and LC3) were improved by hucMSCs. Mechanistically, hucMSCs protected high glucose-induced injury in rat podocytes by activating autophagy and attenuating senescence through the AMPK/mTOR pathway.

CONCLUSIONS

In conclusion, hucMSCs might be a promising therapeutic strategy for the clinical treatment of DN-induced renal damages.