Implications of treatment that target protective mechanisms against diabetic nephropathy

FTO mediates the diabetic kidney disease progression through regulating the m6A modification of NLRP3

BACKGROUND

The objective of our research was to investigate the specific mechanism of FTO in diabetic kidney disease (DKD) progression.

METHODS

The DKD model was established with renal tubular epithelial HK-2 cells and mice in vitro and in vivo. The N6-methyladenosine (m6A) content in cells was detected using dot plot assay and the m6A levels of NLRP3 was detected with the MeRIP assay. The mRNA and protein levels were tested with real-time reverse transcriptase-polymerase chain reaction (RT-qPCR) and western blot. The IL-1β and IL-18 levels were assessed with enzyme-linked immunosorbent assay (ELISA). The cell viability was measured by cell counting kit (CCK)-8 assay and cell pyroptosis was determined with Annexin V and propidium iodide (PI) double staining followed by flow cytometry analysis. RNA-binding protein immunoprecipitation (RIP) and dual luciferase reporter assays were conducted to detect the interaction between FTO and NLRP3. m6A levels were detected by Me-RIP assay. The renal injury was measured by observing the renal morphology and urine and blood levels of relevant indicators.

RESULTS

The results indicated that high glucose treatment induced HK-2 cell pyroptosis. m6A levels were prominently elevated in high glucose treated HK-2 cells while FTO expression were significantly down-regulated. FTO over-expression promoted cell viability but inhibited pyroptosis of HK-2 cells under high glucose (HG) treatment. Moreover, FTO could inhibit NLRP3 expression. RIP and Me-RIP assays indicated that FTO could bind with NLRP3 and regulate its m6A modification level. Further luciferase assay confirmed that FTO binds with the 233-237 bp region of NLRP3. NLRP3 neutralized the function of FTO in the HG stimulated HK-2 cells. In vivo, the H&E staining showed that FTO over-expression alleviated the kidney injury and suppressed the pyroptosis induced by DKD.

CONCLUSION

We found that FTO could inhibit the DKD progression in vivo and in vitro by regulated the m6A modification of NLRP3.

New Insights into the Pleiotropic Actions of Dipeptidyl Peptidase-4 Inhibitors Beyond Glycaemic Control

Dipeptidyl peptidase-4 (DPP-4) is a multifunctional serine ectopeptidase that cleaves and modifies a plethora of substrates, including regulatory peptides, cytokines and chemokines. DPP-4 is implicated in the regulation of immune response, viral entry, cellular adhesion, metastasis and chemotaxis. Regarding its numerous substrates and extensive expression inside the body, multitasking DPP-4 has been assumed to participate in different pathophysiological mechanisms. DPP-4 inhibitors or gliptins are increasingly used for the treatment of type 2 diabetes mellitus. Several reports from experimental and clinical studies have clarified that DPP-4 inhibitors exert many beneficial pleiotropic effects beyond glycaemic control, which are mediated by anti-inflammatory, anti-oxidant, anti-fibrotic and anti-apoptotic actions. The present review will highlight the most recent findings in the literature about these pleiotropic effects and the potential mechanisms underlying these benefits, with a specific focus on the potential effectiveness of DPP-4 inhibitors in coronavirus disease-19 and diabetic kidney disease.

Prediction Model for Early-Stage CKD Using the Naples Prognostic Score and Plasma Indoleamine 2,3-dioxygenase Activity

Purpose

Changes in inflammation, immunity, and nutritional status can promote the development of chronic kidney disease (CKD), and the Naples prognostic score (NPS) reflects changes in these three general clinical parameters. Indoleamine 2.3-dioxygenase (IDO) can block the function of inflammatory cells and inhibit the production of inflammatory cytokines. We examined use of the NPS and IDO activity to predict early-stage CKD.

Patients and Methods

Clinical and demographic parameters and the NPS were recorded for 47 CKD patients and 30 healthy controls. A one-way ANOVA or the rank sum test was used to compare variables in the different groups. Spearman or Pearson correlation coefficients were calculated, and logistic regression was used to identify significant factors. Receiver operating characteristic (ROC) analysis was also performed.

Results

The NPS had a positive correlation with plasma IDO activity and IDO activity was lowest in controls, and increased with CKD stage. ROC analysis indicated that NPS had an area under the curve (AUC) of 0.779 when comparing controls with all CKD patients. A prediction model for CKD (-4.847 + [1.234 × NPS] + [6.160 × plasma IDO activity]) demonstrated significant differences between controls and patients with early-stage CKD, and for patients with different stages of CKD. This model had AUC values of 0.885 (control vs CKD1-4), 0.876 (control vs CKD2), 0.818 (CKD2 vs CKD3), and 0.758 (CKD3 vs CKD4).

Conclusion

A prediction model based on the NPS and IDO provided good to excellent predictions of early-stage CKD.

Efficacy and Safety of Vildagliptin for Type 2 Diabetes in Patients With Diabetic Kidney Disease

BACKGROUND/AIM

Vildagliptin is one of the dipeptidyl peptidase-4 (DPP-4) inhibitors that have been shown to improve hyperglycemia in clinical trials among patients with type 2 diabetes. However, few studies have examined the efficacy of vildagliptin in patients with diabetic kidney disease (DKD).

PATIENTS AND METHODS

Eight patients with DKD received oral vildagliptin 50-100 mg/day. The duration of diabetes was 6.7±5.9 years and observation period was 23.6±9.8 months. Changes in fasting blood glucose, and hemoglobin A1c (HbA1c), estimated glomerular filtration rate (eGFR), and urine protein-to-creatinine ratio (UPCR) were studied before and after the administration of vildagliptin.

RESULTS

Vildagliptin treatment significantly decreased fasting blood glucose and HbA1c, compared to baseline (132±56 mg/dl, p=0.036, 6.0±0.3, p=0.041, respectively). UPCR tended to be decreased, albeit without statistical significance. However, eGFR was decreased after the administration of vildagliptin. No significant adverse effects were observed in all patients during the study.

CONCLUSION

Although the sample size was limited and the observation period was brief, vildagliptin was found to be an effective and reasonably well-tolerated treatment for patients with DKD.

Plasma Asprosin Concentrations are Associated with Progression of Diabetic Kidney Disease

Purpose

To explore the expression of asprosin in subjects with pre-DKD and DKD and to analyze its relationship with kidney injury, inflammation, and glucose and lipid metabolism.

Methods

Based on urine albumin:creatinine ratio (UACr), participants were divided into DM, pre-DKD, and DKD groups. Relevant human physiological and biochemical parameters were detected in the three groups.

Results

We found relatively higher levels of asprosin in both pre-DKD and DKD groups than the DM group. Moreover, data from the Nephroseq database support increased gene expression of asprosin in kidney tissue from DKD patients. Further correlation analysis revealed that the plasma asprosin level was positively correlated with age, waist circumference, waist:hip ratio, systolic blood pressure, creatinine, UACr, triglycerides, HDL-c, fasting insulin, HOMA-IR, and the inflammatory marker G3P and negatively associated with eGFR. Multiple logistical regression analysis showed that asprosin concentration was significantly associated with pre-DKD and DKD after adjusting for sex, age, BMI, WHR, and HOMA-IR, while this correlation was lost after controlling for G3P.

Conclusion

Plasma asprosin is associated with kidney injury in diabetic conditions, and this association might be connected through inflammatory response. Further studies are needed to assess the role and mechanism of asprosin in DKD.

Effect of Sacubitril/Valsartan on Patients Having Heart Failure With Preserved Left Ventricular Ejection Fraction Undergoing Hemodialysis: A Long-term Observational Study

BACKGROUND/AIM

Sacubitril/valsartan (SV), a novel pharmacological class of angiotensin receptor neprilysin inhibitors, is effective in treating heart failure (HF) by inhibiting the degradation of natriuretic peptides and the renin-angiotensin-aldosterone system. However, no studies have observed the long-term effects of SV on patients with HF and preserved left ventricular ejection fraction (LVEF) undergoing hemodialysis (HD) over a long period.

PATIENTS AND METHODS

This single-center retrospective study of 21 months duration involved consecutive patients with HF and preserved LVEF undergoing HD, who received 50-200 mg/day. All patients were followed up regularly, and clinical, biochemical, and echocardiographic parameters were recorded at baseline and during follow-up. The efficacy and safety of SV were also analyzed.

RESULTS

This longitudinal study included nine patients, with a median age of 76 years. The median HD duration was 7 years. At baseline, the mean brain natriuretic peptide (BNP) was 133±73.6 pg/ml and that of LVEF was 66%±9%. After SV therapy, the systolic blood pressure, diastolic blood pressure, and heart rate decreased, albeit without statistical significance. BNP levels, LVEF, left atrial anteroposterior dimension, and left ventricular mass index did not change, compared to baseline values. No adverse effects were observed in any of the patients.

CONCLUSION

SV tended to decrease blood pressure and heart rate in patients with HF and preserved LVEF undergoing HD but did not alter cardiac function assessments, such as BNP or echocardiography.

Associations between cardiometabolic indices and the risk of diabetic kidney disease in patients with type 2 diabetes

BACKGROUND

This study was designed to assess the associations between emerging cardiometabolic indices-the atherogenic index of plasma (AIP), the stress hyperglycemia ratio (SHR), the triglyceride-glucose (TyG) index, and the homeostasis model assessment of insulin resistance (HOMA-IR)-and the incidence of diabetic kidney disease (DKD) in type 2 diabetes (T2D) patients.

METHODS

We consecutively enrolled 4351 T2D patients. The AIP, SHR, TyG index, and HOMA-IR were calculated from baseline parameters. DKD was defined as a urine albumin/creatinine ratio > 30 mg/g or an eGFR < 60 mL/min per 1.73 m. All participants were categorized into tertiles based on the cardiometabolic indices. Multivariate logistic regression models, restricted cubic splines, and receiver operating characteristic (ROC) curves were used for analysis.

RESULTS

A total of 1371 (31.5%) patients were diagnosed with DKD. A restricted cubic spline showed a J-shaped association of the AIP and TyG index with DKD, a log-shaped association between HOMA-IR and DKD, and a U-shaped association between the SHR and DKD incidence. Multivariate logistic regression revealed that individuals in the highest tertile of the four cardiometabolic indices had a significantly greater risk of DKD than did those in the lowest tertile (AIP: OR = 1.08, 95% CI = 1.02-1.14, P = 0.005; SHR: OR = 1.42, 95% CI = 1.12-1.81, P = 0.004; TyG index: OR = 1.86, 95% CI = 1.42-2.45, P < 0.001; HOMA-IR: OR = 2.24, 95% CI = 1.52-3.30, P < 0.001). The receiver operating characteristic curves showed that the HOMA-IR score was better than other indices at predicting the risk of DKD, with an optimal cutoff of 3.532.

CONCLUSIONS

Elevated AIP, SHR, TyG index and HOMA-IR are associated with a greater risk of DKD in patients with T2D. Among these indices, the HOMA-IR score demonstrated the strongest association with and predictive value for DKD incidence.

Safety and Efficacy of Dotinurad on Uric Acid in Patients With Chronic Kidney Disease With Estimated Glomerular Filtration Rate Below 25 mL/Min/1.73 m²

Introduction Dotinurad is being developed as a selective uric acid reabsorption inhibitor. However, its effect on lowering serum uric acid (UA) levels in chronic kidney disease (CKD) patients with severe renal dysfunction is unknown. Therefore, the purpose of this study was to determine the effect of dotinurad on renal function in CKD patients with an estimated glomerular filtration rate (eGFR) below 25 mL/min/1.73 m2. Methods Seven patients with CKD who received dotinurad 0.5 mg to 4 mg per day were studied retrospectively. Changes in UA, eGFR, and urine protein-to-creatinine ratio (UPCR) were analyzed. The observation period was 10.9±2.1 months. Results Serum UA levels were decreased and maintained with dotinurad administration. Nevertheless, there were no improvements noted in renal function. Additionally, no serious adverse effects were identified in any of the patients throughout the observation period. Conclusion Although the sample size in this study was small, our findings demonstrate the efficacy of dotinurad in individuals with advanced CKD who have an eGFR lower than 25 mL/min/1.73 m2.

PGC1-α in diabetic kidney disease: unraveling renoprotection and molecular mechanisms

Mitochondrial dysfunction represents a pivotal aspect of the pathogenesis and progression of diabetic kidney disease (DKD). Central to the orchestration of mitochondrial biogenesis is the peroxisome proliferator-activated receptor γ coactivator 1-α (PGC1-α), a master regulator with a profound impact on mitochondrial function. In the context of DKD, PGC1-α exhibits significant downregulation within intrinsic renal cells, precipitating a cascade of deleterious events. This includes a reduction in mitochondrial biogenesis, heightened levels of mitochondrial oxidative stress, perturbed mitochondrial dynamics, and dysregulated mitophagy. Concurrently, structural and functional abnormalities within the mitochondrial network ensue. In stark contrast, the sustained expression of PGC1-α emerges as a beacon of hope in maintaining mitochondrial homeostasis within intrinsic renal cells, ultimately demonstrating an impressive renoprotective potential in animal models afflicted with DKD. This comprehensive review aims to delve into the recent advancements in our understanding of the renoprotective properties wielded by PGC1-α. Specifically, it elucidates the potential molecular mechanisms underlying PGC1-α's protective effects within renal tubular epithelial cells, podocytes, glomerular endothelial cells, and mesangial cells in the context of DKD. By shedding light on these intricate mechanisms, we aspire to provide valuable insights that may pave the way for innovative therapeutic interventions in the management of DKD.

The role of a novel mineralocorticoid receptor antagonist, finerenone, in chronic kidney disease: mechanisms and clinical advances

BACKGROUND

Chronic kidney disease (CKD) poses a significant health risk in contemporary society. Current CKD treatments primarily involve renin-angiotensin-aldosterone system inhibitors and mineralocorticoid receptor antagonists, albeit associated with hyperkalemia risks. A novel selective mineralocorticoid receptor antagonist, finerenone, offers a promising, safer alternative for CKD therapy. This review comprehensively assesses the role and efficacy of finerenone in CKD treatment by analyzing clinical and animal studies. Emerging evidence consistently supports finerenone's ability to effectively slow the progression of CKD. By targeting the mineralocorticoid receptor, finerenone not only mitigates renal damage but also exhibits a favorable safety profile, minimizing hyperkalemia concerns.

CONCLUSION

Finerenone emerges as a valuable addition to CKD therapy, demonstrating potential benefits in delaying CKD progression while minimizing side effects. Nevertheless, further clinical trials are necessary to provide a comprehensive understanding of its safety and efficacy.

Neomangiferin, a Naturally Occurring Mangiferin Congener, Inhibits Sodium-Glucose Co-transporter-2: An In silico Approach

Type 2 diabetes is a major health concern contributing to most of diabetic cases worldwide. Mangiferin and its congeners are known for their diverse pharmacological properties. This study sought to investigate the inhibitory property of naturally occurring mangiferin congeners on sodium-glucose co-transporter 2 protein (SGLT-2) using comprehensive computational methods. The naturally occurring mangiferin congeners were subjected to molecular docking, molecular dynamics (MDs) simulation (100 ns), molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) binding free energy, density functional theory calculations (B3LYP 6-31G basis set), and ADMET approaches to identify potential SGLT-2 inhibitor. The molecular docking studies revealed neomangiferin (-9.0 kcal/mol) as the hit molecule compared with dapagliflozin (-8.3 kcal/mol). Root-mean-square deviation (RMSD) and root-mean-square fluctuation (RMSF) plots from the MD simulations established that neomangiferin stabilizes SGLT-2 better than the dapagliflozin, a standard drug. The MM-PBSA binding free energy calculations showed that neomangiferin (-26.05 kcal/mol) elicited better binding affinity than dapagliflozin (-17.42 kcal/mol). The electronic studies showed that neomangiferin (3.48 eV) elicited high electrophilicity index compared with mangiferin (3.31 eV) and dapagliflozin (2.11 eV). Also, the ADMET properties showed that the hit molecule is safe when administered to diabetic subjects. The current in silico studies suggest that neomangiferin could emerge as a promising lead molecule as a SGLT-2 inhibitor.

Impact of Sodium-Glucose Cotransporter-2 Inhibitors in the Management of Chronic Kidney Disease: A Middle East and Africa Perspective

Chronic kidney disease (CKD) is a major public health concern in the Middle East and Africa (MEA) region and a leading cause of death in patients with type 2 diabetes mellitus (T2DM) and hypertension. Early initiation of sodium-glucose cotransporter - 2 inhibitors (SGLT-2i) and proper sequencing with renin-angiotensin-aldosterone system inhibitors (RAASi) in these patients may result in better clinical outcomes due to their cardioprotective properties and complementary mechanisms of action. In this review, we present guideline-based consensus recommendations by experts from the MEA region, as practical algorithms for screening, early detection, nephrology referral, and treatment pathways for CKD management in patients with hypertension and diabetes mellitus. This study will help physicians take timely and appropriate actions to provide better care to patients with CKD or those at high risk of CKD.

Effects of Oral Semaglutide on Renal Function in Diabetic Kidney Disease: A Short-term Clinical Study

BACKGROUND/AIM

In the SUSTAIN-6 trial, semaglutide reduced the risk of worsening nephropathy in patients with type 2 diabetes. The objective of this retrospective study was to elucidate the effect and safety of oral semaglutide (Rybelsus®) in patients with diabetic kidney disease (DKD).

PATIENTS AND METHODS

Six patients with DKD received 3 mg/day semaglutide orally. The observation period was 9.0±5.0 months. Changes in estimated glomerular filtration rate (eGFR), urinary protein, fasting blood glucose, and hemoglobin A1c were studied from 6 months before the administration of oral semaglutide until 6 months after administration.

RESULTS

The change in eGFR over the 6 months prior to semaglutide administration was -1.2±1.6 ml/min/1.73 m2, showing a trend for a decrease; although not statistically significant, the change at 6 months after oral semaglutide initiation showed improved eGFR (1-50.7±1.8 ml/min/1.73 m2). Proteinuria was not reduced after treatment with oral semaglutide. No significant adverse effects (including retinopathy) were observed in any patient during the study.

CONCLUSION

Despite the small sample size and short observation period, oral semaglutide was found to be a relatively well-tolerated drug for patients with DKD.

The Current Place of DPP4 Inhibitors in the Evolving Landscape of Type 2 Diabetes Management: Is It Time to Bid Adieu?

During the last decade, the landscape of type 2 diabetes (T2D) management has been completely transformed, moving from a glucose-centric perspective to a holistic approach that also takes into account weight control and organ protection. Dipeptidyl peptidase-4 inhibitors (DPP4i) are oral agents that have been used for the treatment of T2D for almost 20 years. Although they present an excellent safety profile, including the risk of hypoglycemia, they lack the spectacular cardiorenal benefits and weight-loss effects of the newer antidiabetic agents. This poses the question of whether they still deserve a place in the arsenal of drugs against T2D. In this article, we use a hypothetical case scenario to illustrate possible patient profiles where DPP4i could prove useful in the clinical setting. We discuss the advantages and disadvantages of the category, focusing on glycemic control, weight management, and cardiorenal protection, which are the pillars of modern T2D management, also considering its safety profile and cost-effectiveness. We conclude that in most cases, DPP4i present a more favorable risk-benefit ratio compared to sulfonylureas, which are still widely prescribed throughout the world. We also suggest that future research should clarify the reasons behind the contradictory findings between human and animal studies on cardiorenal effects of the class and identify subgroups of patients who would derive most benefit with DPP4i treatment.

Deletion of protein tyrosine phosphatase SHP-1 restores SUMOylation of podocin and reverses the progression of diabetic kidney disease

Both clinical and experimental data suggest that podocyte injury is involved in the onset and progression of diabetic kidney disease (DKD). Although the mechanisms underlying the development of podocyte loss are not completely understood, critical structural proteins such as podocin play a major role in podocyte survival and function. We have reported that the protein tyrosine phosphatase SHP-1 expression increased in podocytes of diabetic mice and glomeruli of patients with diabetes. However, the in vivo contribution of SHP-1 in podocytes is unknown. Conditional podocyte-specific SHP-1-deficient mice (Podo-SHP-1-/-) were generated to evaluate the impact of SHP-1 deletion at four weeks of age (early) prior to the onset of diabetes and after 20 weeks (late) of diabetes (DM; Ins2+/C96Y) on kidney function (albuminuria and glomerular filtration rate) and kidney pathology. Ablation of the SHP-1 gene specifically in podocytes prevented and even reversed the elevated albumin/creatinine ratio, glomerular filtration rate progression, mesangial cell expansion, glomerular hypertrophy, glomerular basement membrane thickening and podocyte foot process effacement induced by diabetes. Moreover, podocyte-specific deletion of SHP-1 at an early and late stage prevented diabetes-induced expression of collagen IV, fibronectin, transforming growth factor-β, transforming protein RhoA, and serine/threonine kinase ROCK1, whereas it restored nephrin, podocin and cation channel TRPC6 expression. Mass spectrometry analysis revealed that SHP-1 reduced SUMO2 post-translational modification of podocin while podocyte-specific deletion of SHP-1 preserved slit diaphragm protein complexes in the diabetic context. Thus, our data uncovered a new role of SHP-1 in the regulation of cytoskeleton dynamics and slit diaphragm protein expression/stability, and its inhibition preserved podocyte function preventing DKD progression.

Serum JKAP reflects Th2 and Th17 cell levels, and diabetic nephropathy risk and severity in diabetes mellitus patients

Objective: This study aimed to explore the potency of serum JKAP for estimating diabetic nephropathy risk in diabetes mellitus (DM) patients. Methods: Serum JKAP was detected in 212 DM patients. According to urinary albumin-to-creatinine ratio, DM patients were divided into normoalbuminuria, microalbuminuria and macroalbuminuria groups. Results: JKAP declined in the macroalbuminuria group versus normoalbuminuria group (p < 0.001). In DM patients, JKAP inversely correlated with Th17 cells (p < 0.001) but positively related to Th2 cells (p = 0.003). After adjustment, JKAP independently estimated lower risks of albuminuria (microalbuminuria + macroalbuminuria; odds ratio = 0.966, p < 0.001) and macroalbuminuria (odds ratio = 0.948; p = 0.002). Conclusion: Serum JKAP reflects increased Th2 cells, decreased Th17 cells, and lower diabetic nephropathy risk and severity in DM patients.

Current findings on the efficacy of incretin-based drugs for diabetic kidney disease: A narrative review

Diabetic kidney disease (DKD) is the most common cause of chronic kidney disease (CKD), leading end-stage renal disease. Thus, DKD is one of the most important diabetic complications. Incretin-based therapeutic agents, such as glucagon-like peptide-1 (GLP-1) receptor agonizts and dipeptidyl peptidase-4 (DPP-4) inhibitors have been reported to elicit vasotropic actions, suggesting a potential for effecting reduction in DKD. Glucose-dependent insulinotropic polypeptide (GIP) is also classified as an incretin. However, the insulin action after GIP secretion is known to be drastically reduced in patients with type 2 diabetes. Therefore, GIP has been formally considered unsuitable as a treatment for type 2 diabetes in the past. This concept is changing as it has been reported that resistance to GIP can be reversed and its effect restored with improved glycemic control. The development of novel dual- or triple- receptor agonizts that can bind to the receptors, not only for GLP-1 but also to GIP and glucagon receptors, is intended to simultaneously address several metabolic pathways including protein, lipid, and carbohydrate metabolism. These led to the development of GIP receptor agonist-based drugs for type 2 diabetes. The possibility of combined GIP/GLP-1 receptor agonist was also explored. The novel dual GIP and GLP-1 receptor agonist tirzepatide has recently been launched (Mounjaro®, Lilly). We have revealed precise mechanisms of the renoprotective effect of GLP-1 receptor agonizts or DPP-4 inhibitors, while the long-term effect of tirzepatide will need to be determined and its potential effects on kidneys should be properly tested.

Effect of finerenone on diabetic kidney disease outcomes with estimated glomerular filtration rate below 25 mL/min/1.73 m2

Background

In the Finerenone in Reducing Cardiovascular Mortality and Morbidity in Diabetic Kidney Disease trial, finerenone reduced the risk of cardiovascular events in patients with chronic kidney disease (CKD) and type 2 diabetes, while in the Finerenone in Reducing Kidney Failure and Disease Progression in Diabetic Kidney Disease trial, it improved renal and cardiovascular outcomes in patients with advanced CKD. However, no previous studies have assessed patients with CKD and type 2 diabetes with an estimated glomerular filtration rate (eGFR) below 25 mL/min/1.73 m².

Methods

Nine patients with CKD and type 2 diabetes who received finerenone 10 mg/day were analyzed retrospectively. Changes in eGFR, urinary protein, and serum potassium levels were studied from 1 year before administration of finerenone until 6 months after administration.

Results

The mean baseline eGFR slope was -7.63 ± 9.84 (mL/min/1.73 m²/year). After finerenone treatment, the mean eGFR slope significantly improved -1.44 ± 3.17 (mL/min/1.73 m²/6 months, P=0.038). However, finerenone treatment did not significantly reduce proteinuria. Furthermore, finerenone did not increase serum potassium levels.

Conclusions

Patients treated with finerenone showed a significantly slower decline in eGFR. Furthermore, aside from the present study, no reports have indicated the effectiveness of finerenone in patients with advanced CKD with an eGFR below 25 mL/min/1.73 m². As confirmed in our clinical trials, the finding that finerenone is effective in a wide range of renal functions can be generalized to clinical practice. However, sample size in this study was small. Thus, further large-scale investigations will be needed.

Predictive significance of glomerular insulin receptor substrate-1 in patients with diabetic kidney disease

Background

In rodents, glomerular expression of insulin receptor substrate 1 (IRS1) is decreased in diabetic kidney disease (DKD) and reduced associated functioning is involved in the development and progression of DKD. This study aimed to evaluate the significance of glomerular IRS1 expression in DKD patients, and investigated whether glomerular IRS1 expression can reflect renal pathology and predict renal outcomes.

Methods

This study included 10 patients who underwent renal biopsy and were diagnosed with DKD or minor glomerular abnormality (MGA). IRS1-positive cells were determined based on renal biopsy and immunostaining, and the associations of the number of these cells with baseline and prognostic parameters were analyzed.

Results

IRS1-positive cells were significantly decreased in DKD than in MGA. IRS1 positivity tended to be negatively correlated with global glomerulosclerosis and tubulointerstitial fibrosis. The rate of change in estimated glomerular filtration rate before and 12 months after renal biopsy was positively correlated to the number of IRS1-positive cells. Furthermore, a tendency towards negative correlation was observed between the number of glomerular IRS1-positive cells and the proteinuria.

Conclusions

This study shows the glomerular IRS1-positive cell count was significantly decreased in DKD, and that the degree IRS1 positivity was partially correlated with renal pathology and function.

Role of insulin signaling and its associated signaling in glomerulus for diabetic kidney disease

The number of patients with diabetic kidney disease (DKD) has been rising significantly over the last several decades and is one of the most frequent causes of chronic kidney disease (CKD) in the United States. Hyperglycemia accelerates development of DKD, a direct result of increased intracellular glucose availability. Two large clinical studies, the Diabetes Control and Complications Trial in type 1 diabetes and the United Kingdom Prospective Diabetes Study in type 2 diabetes showed that intensive glycemic control delayed the onset and the progression of DKD. On the other hand, it is reported that glycemic control alone is not sufficient to control DKD progression. Recent data support that insulin signaling and its associated signaling contribute significantly to preserve glomerular function. However, little is known about the key regulators of insulin signaling in glomerular component cells. In this review, we summarize the novel knowledge regarding the reno-protective effects of insulin signaling or its associated signaling in glomerular constituent cells on DKD.

Effects of incretin-based therapeutic agents including tirzepatide on renal outcomes in patients with type 2 diabetes: A systemic review and meta-analysis

Background

This meta-analysis was conducted to investigate the effects of incretin-based therapeutic agents, including the latest agent tirzepatide, on renal outcomes in patients with type 2 diabetes.

Methods

MEDLINE (via PubMed) and Cochrane databases were searched for studies involving incretin-based therapeutic agents up to July 2022. Randomized and controlled trials comparing incretin-based therapeutic agents with placebo or other antidiabetic agents, and reporting renal outcomes were selected. The inclusion criteria were items related to the effects on albuminuria and the kidney-specific composite outcomes. A network meta-analysis was conducted to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

Twelve trials consisting of 75,346 participants were included in this meta-analysis. Glucagon-like peptide-1 (GLP-1) receptor agonists reduced the risk of the kidney-specific composite outcome by 21% (HR 0.79, 95% CI 0.75-0.85), and worsening albuminuria by 24% (HR 0.76, 95% CI 0.71-0.82). In particular, the dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 receptor agonist tirzepatide remarkably reduced the risk of the kidney-specific composite outcome by 45% (HR 0.55, 95% CI 0.40-0.77), and worsening albuminuria by 62% (HR 0.38, 95% CI 0.24-0.61).

Conclusions

Among incretin-based therapeutic agents, tirzepatide was associated with a significantly reduced risk of diabetic kidney disease.

Multicentric IL-5-positive Castleman Disease With Nephrotic Syndrome Relapsed After Rituximab Treatment

BACKGROUND/AIM

To date, no reports of interleukin (IL)-5-producing Castleman disease with nephrotic syndrome and moreover no reports of relapse after remission with rituximab treatment, have been published.

CASE REPORT

A 67-year-old male presented to the Osaka Medical and Pharmaceutical University Hospital with a history of low-grade fever, papules, and nephrotic syndrome. Lymph nodes were palpated in the inguinal region. The patient showed anemia, eosinophilia, polyclonal hypergammaglobulinemia, and elevated interleukin (IL)-6 levels. Patient's serum IL-5 and IL-6 levels were measured using ELISA and immunohistochemical staining of lymph nodes was performed with antibodies specific to CD134. Histological examination confirmed diagnosis of a plasma cell variant of Castleman disease. After a total of four weekly doses of rituximab, urinary protein disappeared, and skin symptoms improved. However, one month after rituximab treatment, the skin rash worsened again, and eosinophils and IL-5 were elevated significantly.

CONCLUSION

This is the first report of recurrent Castleman disease with direct evidence of increased serum IL-5. It may be reasonable to use rituximab, an anti-CD20 antibody for treating the disease, however, for IL-5-producing cases the effect of rituximab may be partial.

A Narrative Review of Diabetic Kidney Disease: Previous and Current Evidence-Based Therapeutic Approaches

Diabetic kidney disease (DKD) is one of the most important diabetic complications. DKD is also the most common cause of chronic kidney disease (CKD) and end-stage renal disease. This review focused on potential therapeutic drugs for which there is established evidence of treatment for DKD. The earliest evidence for DKD treatment was established with renin-angiotensin system (RAS) inhibitors; however, their efficacy was partial. Recently, the sodium-glucose co-transporter 2 (SGLT2) inhibitors, including empagliflozin (EMPA-REG Outcome), canagliflozin (CREDENCE trial), and dapagliflozin (DAPA-CKD), demonstrated a significant and clinically relevant reduction in the risks of albuminuria and progression of nephropathy, doubling of serum creatinine levels, and initiation of renal replacement therapy. Additionally, incretin-based therapeutic agents, such as glucagon-like peptide 1, liraglutide (LEADER), and dipeptidyl peptidase 4 inhibitors, linagliptin (CARMERINA) have elicited vasotropic actions, suggesting a potential for reducing the risk of DKD. Until recently, mineralocorticoid receptor antagonists (MRAs) have not been suitable for DKD treatment because of their adverse effect of hyperkalemia. In contrast, finerenone, a non-steroidal MRA, significantly reduced renal composite endpoint without severe hyperkalemia that would force its discontinuation (FIDELIO-DKD). Thus, the mainstay treatments of DKD are RAS inhibitors, SGLT2 inhibitors, incretin-based therapeutic agents, and non-steroidal MRA, or in other words, the DKD "fantastic four".

Expression of Ferroptosis-Related Genes is Correlated with Immune Microenvironment in Diabetic Kidney Disease

OBJECTIVE

This study aims to explore the correlation between ferroptosis and immune microenvironment (IME) in diabetic kidney disease (DKD) to provide a new clue for exploring the underlying molecular mechanisms.

METHODS

Corresponding RNA data of DKD patients were downloaded from GEO databases. The weighted gene co-expression network analysis (WGCNA) was used to construct the network, and the selected hub genes, then, overlapped with ferroptosis-related genes (FRGs) from FerrDb. Consensus clustering was performed to identify new molecular subgroups. ESTIMATE, TIMER and ssGSEA analyses were applied to determinate the IME and immune status. Functional analyses including GO, KEGG and GSEA were conducted to elucidate the underlying mechanisms.

RESULTS

Two molecular subtypes were identified based on the expression of FRGs. ESTIMATE algorithm revealed that there were significant differences in ESTIMATE score between these two clusters of DKD patients, with no significant difference found in stromal score and immune score. In addition, TIMER algorithm indicated there was a significant difference in the degree of T cell infiltration. The ssGSEA algorithm showed immunity was mainly concentrated in thick ascending limb and distal convoluted tubule in adult kidney. GO, KEGG and GSEA analyses revealed that the differentially expressed genes (DEGs) were mainly enriched in immune and metabolism associated pathways.

CONCLUSION

The ferroptosis may be induced by dysregulation of IME, thereby accelerating the progression of DKD. Our work could be applied to provide a new clue for exploring the underlying molecular mechanisms and sheds novel light on the therapy strategy of DKD.

Hypoxia-inducible factor-prolyl hydroxylase inhibitors for renal anemia in chronic kidney disease: Advantages and disadvantages

Anemia is a common feature and complication of chronic kidney disease (CKD). Erythropoiesis-stimulating agents (ESAs) and recombinant human erythropoietin have been used widely in renal anemia treatment. Recently, hypoxia-inducible factor-prolyl hydroxylase domain inhibitors (HIF-PHIs) that may improve the treatment of renal anemia patients were launched. Previous studies indicated that HIF-PHIs may decrease hepcidin levels and modulate iron metabolism, thereby increasing total iron-binding capacity and reducing the need for iron supplementation. Furthermore, HIF-PHIs can reduce inflammation and oxidative stress in CKD. Recombinant erythropoietin has become a routine treatment for patients with CKD and end-stage renal disease with relatively few adverse effects. However, higher doses of recombinant erythropoietin have been demonstrated to be an independent predictor of mortality in patients under hemodialysis. Phase III clinical trials of HIF-PHIs in patients with anemia and dialysis-dependent CKD have shown their efficacy and safety in both non-dialysis and dialysis CKD patients. However, HIFα binds to specific hypoxia-response elements in the vascular endothelial growth factor or retinoic acid-related orphan receptor gamma t (RORγt) promoter, which may be involved in the progression of cancer, psoriasis, and rheumatoid arthritis. In this paper, we have summarized the mechanism, clinical application, and clinical trials of HIF-PHIs in the treatment of renal anemia and aimed to provide an overview of the new drugs in clinical practice, as well as reconsider the advantages and disadvantages of HIF-PHIs and ESAs. Presently, there are not enough clinical studies examining the effects of long-term administration of HIF-PHIs. Therefore, further studies will be needed.

Mitochondria in Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the leading cause of end stage renal disease (ESRD) in the USA. The pathogenesis of DKD is multifactorial and involves activation of multiple signaling pathways with merging outcomes including thickening of the basement membrane, podocyte loss, mesangial expansion, tubular atrophy, and interstitial inflammation and fibrosis. The glomerulo-tubular balance and tubule-glomerular feedback support an increased glomerular filtration and tubular reabsorption, with the latter relying heavily on ATP and increasing the energy demand. There is evidence that alterations in mitochondrial bioenergetics in kidney cells lead to these pathologic changes and contribute to the progression of DKD towards ESRD. This review will focus on the dialogue between alterations in bioenergetics in glomerular and tubular cells and its role in the development of DKD. Alterations in energy substrate selection, electron transport chain, ATP generation, oxidative stress, redox status, protein posttranslational modifications, mitochondrial dynamics, and quality control will be discussed. Understanding the role of bioenergetics in the progression of diabetic DKD may provide novel therapeutic approaches to delay its progression to ESRD.

APX-115, a pan-NADPH oxidase inhibitor, protects development of diabetic nephropathy in podocyte specific NOX5 transgenic mice

NADPH oxidases (NOXs) are comprised of different isoforms, NOX1 to 5 and Duox1 and 2, and they trigger diabetic nephropathy (DN) in the patients with diabetes mellitus. Recently, it was shown that, compared to the other isoforms, the expression of NOX5 was increased in the patients with DN and, NOX5 has been suggested to be important in the development of therapeutic agents. The effect of pan-NOX inhibition by APX-115 has also been investigated in type 2 diabetic mice. However, since NOX5 is absent in mice, we evaluated the effect of pan-NOX inhibition by APX-115 in Nox5 transgenic mouse. Wild type and renal podocyte specific NOX5 transgenic mice (NOX5 pod+) were fed with high-fat diet (60% kcal fat) and treated with APX-115 (60 mg/kg) by oral gavage for 14 weeks. APX-115 significantly improved pancreatic beta cell function by decreased fasting blood glucose levels and increased insulin levels. Further, the total serum cholesterol, triglycerides, and urinary albumin/creatinine levels were also significantly decreased by APX-115 treatment. Increased NOX5 mRNA expressions, increased desmin levels, and reduced podocin protein expressions in the kidney of NOX5 pod + mice were also significantly restored to normal levels by APX-115 treatment. Moreover, APX-115 inhibited the expression of inflammation-related proteins such as TRAF6. Collectively, these data suggest that APX-115 might be a promising therapeutic agent for the treatment of DN because of its pan-NOX inhibitory activity, including its NOX5 inhibitory activity, and also owing to its anti-inflammatory effect.

Diabetes-Induced Reactive Oxygen Species: Mechanism of Their Generation and Role in Renal Injury

Diabetes induces the onset and progression of renal injury through causing hemodynamic dysregulation along with abnormal morphological and functional nephron changes. The most important event that precedes renal injury is an increase in permeability of plasma proteins such as albumin through a damaged glomerular filtration barrier resulting in excessive urinary albumin excretion (UAE). Moreover, once enhanced UAE begins, it may advance renal injury from progression of abnormal renal hemodynamics, increased glomerular basement membrane (GBM) thickness, mesangial expansion, extracellular matrix accumulation, and glomerulosclerosis to eventual end-stage renal damage. Interestingly, all these pathological changes are predominantly driven by diabetes-induced reactive oxygen species (ROS) and abnormal downstream signaling molecules. In diabetic kidney, NADPH oxidase (enzymatic) and mitochondrial electron transport chain (nonenzymatic) are the prominent sources of ROS, which are believed to cause the onset of albuminuria followed by progression to renal damage through podocyte depletion. Chronic hyperglycemia and consequent ROS production can trigger abnormal signaling pathways involving diverse signaling mediators such as transcription factors, inflammatory cytokines, chemokines, and vasoactive substances. Persistently, increased expression and activation of these signaling molecules contribute to the irreversible functional and structural changes in the kidney resulting in critically decreased glomerular filtration rate leading to eventual renal failure.

Incretin-Based Therapy for Prevention of Diabetic Vascular Complications

Diabetic vascular complications are the most common cause of mortality and morbidity worldwide, with numbers of affected individuals steadily increasing. Diabetic vascular complications can be divided into two categories: macrovascular andmicrovascular complications. Macrovascular complications include coronary artery diseaseand cerebrovascular disease, while microvascular complications include retinopathy and chronic kidney disease. These complications result from metabolic abnormalities, including hyperglycemia, elevated levels of free fatty acids, and insulin resistance. Multiple mechanisms have been proposed to mediate the adverse effects of these metabolic disorders on vascular tissues, including stimulation of protein kinase C signaling and activation of the polyol pathway by oxidative stress and inflammation. Additionally, the loss of tissue-specific insulin signaling induced by hyperglycemia and toxic metabolites can induce cellular dysfunction and both macro- and microvascular complications characteristic of diabetes. Despite these insights, few therapeutic methods are available for the management of diabetic complications. Recently, incretin-based therapeutic agents, such as glucagon-like peptide-1 and dipeptidyl peptidase-4 inhibitors, have been reported to elicit vasotropic actions, suggesting a potential for effecting an actual reduction in diabetic vascular complications. The present review will summarize the relationship between multiple adverse biological mechanisms in diabetes and putative incretin-based therapeutic interventions intended to prevent diabetic vascular complications.

[Role of angiostatins in diabetic complications]

Angiogenesis is a process through which new blood vessels form from pre-existing vessels. Angiogenesis is regulated by a number of factors of peptide nature. Disbalance of angiogenic system appears to be the major causative factor contributing vascular abnormalities in diabetes mellitus, resulting in various complications. Angiostatins, which are kringle-containing fragments of plasminogen/plasmin, are known to be powerful physiological inhibitors of neovascularization. In the present review, current literature data on peculiarities of production of angiostatins and their functioning at diabetes mellitus are summarized and analyzed for the first time. Also, role of angiostatins in the pathogenesis of typical diabetic complications, including retinopathies, nephropathies and cardiovascular diseases, is discussed. Data presented in this review may be useful for elaboration of novel effective approaches for diagnostics and therapy of vascular abnormalities in diabetes mellitus.

Effects of pentoxifylline on proteinuria and glucose control in patients with type 2 diabetes: a prospective randomized double-blind multicenter study

BACKGROUND

Pentoxifylline is a methylxanthine derivative with significant anti-inflammatory, anti-fibrotic, and anti-proliferative properties. Studies have shown that pentoxifylline may have renoprotective effects in patients with diabetic nephropathy. However, most of these studies were limited by small sample sizes. Therefore, we investigated whether pentoxifylline could reduce proteinuria in patients with diabetic nephropathy and residual proteinuria who received an angiotensin-converting enzyme inhibitor (ACEI) or an angiotensin II receptor blocker (ARB). We also studied the effects of pentoxifylline on glycemic control, insulin resistance, and inflammatory parameters.

METHODS

This was a prospective, randomized double-blind, placebo-controlled, multi-center study. A total of 174 patients with type 2 diabetes and albuminuria (>30 mg/g of creatinine) who were taking the recommended dosage of ACEI or ARB for > 6 months and receiving conventional therapy for diabetes were randomly assigned to receive pentoxifylline (1200 mg, daily; n = 87) or a placebo (n = 87) for 6 months. The endpoints were the effects of pentoxifylline on proteinuria, renal function, glucose control, and inflammatory parameters.

RESULTS

The percentage changes in proteinuria from baseline in the pentoxifylline and placebo groups were a decrease of 23 % and 4 %, respectively (p = 0.012). In addition, significant reductions in fasting plasma glucose, glycated hemoglobin, and insulin resistance according to the homeostasis model assessment were observed in the pentoxifylline group compared to those in the placebo group. However there was no significant difference in serum tumor necrosis factor (TNF)-α between the groups.

CONCLUSIONS

Pentoxifylline therapy reduced proteinuria and improved glucose control and insulin resistance without significant change of serum TNF-α in patients with type 2 diabetic nephropathy. Therefore, pentoxifylline is a potential therapeutic alternative for treating diabetes and diabetic nephropathy.

TRIAL REGISTRATION

NCT01382303.

Harnessing the immunological properties of stem cells as a therapeutic option for diabetic nephropathy

Diabetic nephropathy is the leading and possibly the most devastating complication of diabetes, with a prevalence ranging from 25 to 40 % in diabetic individuals, and as such represents an important challenge for public health worldwide. As a major cause of end-stage renal disease, diabetic nephropathy also accounts for a large proportion of deaths in diabetic individuals. To date, therapeutic options for overt diabetic nephropathy include medical interventions to reduce blood glucose levels and to control blood pressure and proteinuria. Recent evidence suggests a strong role for inflammation in the development and progression of diabetic nephropathy. Various immune cells, cytokines and chemokines have been implicated in the onset of diabetic nephropathy, while immune-related transcription factors and adhesion molecules have been correlated with the establishment of a renal proinflammatory microenvironment. Both inflammation and immune activation may promote severe distress in the kidney, with subsequent increased local fibrosis, ultimately leading to the development of end-stage renal disease. Stem cells are undifferentiated cells capable of regenerating virtually any organ or tissue and bearing important immunoregulatory and anti-inflammatory properties. Due to the aforementioned considerations, significant interest has been ignited with regard to the use of stem cells as novel therapeutics for diabetic nephropathy. Here, we will be examining in detail how anti-inflammatory properties of different populations of stem cells may offer novel therapy for the treatment of diabetic nephropathy.

Diabetic kidney disease: from epidemiology to clinical perspectives

With worldwide epidemic of diabetes mellitus, diabetic nephropathy which is one of the major causes of microvascular complication has become a serious concern in Korea as well as the rest of the world. In view of its significance, there is an urgent and paramount need for proper managements that could either deter or slow the progression of diabetic nephropathy. Despite advances in care, ever increasing number of patients suffering from diabetic kidney disease and from end-stage renal disease implies that the current management is not adequate in many aspects. The reasons for these inadequacies compromise lack of early diagnosis, failure to intervene with timely and aggressive manner, and lack of understanding on the kind of interventions required. Another issue equally important for the adequate care of patients with diabetic nephropathy is an understanding of past, present and future epidemiology of diabetic nephropathy which serves, especially in Korea, as a material determining standard diagnosis and treatment and a national health-policy decision.

High risk of ESRD in type 1 diabetes: new strategies are needed to retard progressive renal function decline

Care of patients with type 1 diabetes (T1D) has changed during the past 30 years. Tools to control hyperglycemia have improved and it was shown that improvement in glycemic control diminished the risk of late diabetic complications, including nephropathy. Moreover, in patients with impaired renal function, aggressive treatment of hypertension and renoprotective blockade of the renin-angiotensin system were shown to postpone end-stage renal disease (ESRD), albeit for a short while. Despite these achievements, the incidence of ESRD caused by T1D in the US population has not decreased but rather has increased over the past 20 years, although it now occurs at slightly older ages. This state of affairs is a call to action. This should begin with adopting a new model of diabetic nephropathy in human beings. In that model, instead of microalbuminuria or proteinuria, the focus should be on diagnosis and treatment of progressive renal function decline that leads to ESRD. Such a model has received significant support in clinical and epidemiologic studies. Investigation of mechanisms of such progressive renal function decline should help in the identification of new therapeutic targets and the development of new interventions. To evaluate these interventions, accurate diagnostic algorithms are needed so T1D patients will be stratified according to time to onset to ESRD. Consistent with concepts of personalized medicine, the new interventions should be tailored to and evaluated in patients predicted to have rapid, moderate, or even slow progression to ESRD.

Can existing drugs approved for other indications retard renal function decline in patients with type 1 diabetes and nephropathy?

Mounting evidence from human, animal, and in vitro studies indicates that existing drugs, developed to treat other disorders, also might be effective in preventing or slowing the progression of diabetic nephropathy to end-stage renal disease. Examples of such drugs include the urate-lowering agent allopurinol, the anti-tumor necrosis factor agents etanercept and infliximab, and the immunomodulating drug abatacept. Because some of these medications are already on the market and have been used for a number of years for other indications, they can be tested immediately in human beings for a beneficial effect on renal function in diabetes. Special emphasis should be placed on evaluating the use of these drugs early in the course of diabetic nephropathy when renal damage is most likely to be reversible and interventions can yield the greatest delay to end-stage renal disease.