Dipeptidyl Peptidase-4 Inhibitors and Diabetic Kidney Disease: A Narrative Review

Kidney and Cardiovascular Effectiveness of Empagliflozin Compared With Dipeptidyl Peptidase-4 Inhibitors in Patients With Type 2 Diabetes

Placebo-controlled trials of sodium-glucose co-transporter-2 inhibitors demonstrate kidney and cardiovascular benefits for patients with type 2 diabetes and chronic kidney disease (CKD). We used real-world data to compare the kidney and cardiovascular effectiveness of empagliflozin to dipeptidyl peptidase-4 inhibitors (DPP4is), a commonly prescribed antiglycemic medication, in a diverse population with and without CKD. Using electronic health record data from 20 large US health systems, we leveraged propensity overlap weighting to compare the outcomes for empagliflozin and DPP4i initiators with type 2 diabetes between 2016 and 2020. The primary composite kidney outcome included 40% estimated glomerular filtration rate decrease, incident end-stage kidney disease, or all-cause mortality through 2 years or censoring. We also assessed cardiovascular and safety outcomes. Of 62,197 new users, 20,279 initiated empagliflozin and 41,918 initiated DPP4i. Over a median follow-up of 1.1 years, empagliflozin prescription was associated with a lower risk of the primary outcome (hazard ratio [HR] 0.75, 95% confidence interval [CI] 0.65 to 0.87) than DPP4is. The risks for mortality (HR 0.76, 95% CI 0.62 to 0.92) and a cardiovascular composite of stroke, myocardial infarction, or all-cause mortality (HR 0.81, 95% CI 0.70 to 0.95) were also lower for empagliflozin initiators. No difference in heart failure hospitalization risk between groups was observed. Genital mycotic infections were more common in patients prescribed empagliflozin (HR 1.72, 95% CI 1.58 to 1.88). Empagliflozin was associated with a lower risk of the primary outcome in patients with CKD (HR 0.68, 95% CI 0.53 to 0.88) and those without CKD (HR 0.79, 95% CI 0.67 to 0.94). In conclusion, the initiation of empagliflozin was associated with a significantly lower risk of kidney and cardiovascular outcomes than DPP4is over a median of just over 1 year. The association with a lower risk for clinical outcomes was apparent even for patients without known CKD at baseline.

Diabetes and Renal Complications: An Overview on Pathophysiology, Biomarkers and Therapeutic Interventions

Diabetic kidney disease (DKD) is a major microvascular complication of both type 1 and type 2 diabetes. DKD is characterised by injury to both glomerular and tubular compartments, leading to kidney dysfunction over time. It is one of the most common causes of chronic kidney disease (CKD) and end-stage renal disease (ESRD). Persistent high blood glucose levels can damage the small blood vessels in the kidneys, impairing their ability to filter waste and fluids from the blood effectively. Other factors like high blood pressure (hypertension), genetics, and lifestyle habits can also contribute to the development and progression of DKD. The key features of renal complications of diabetes include morphological and functional alterations to renal glomeruli and tubules leading to mesangial expansion, glomerulosclerosis, homogenous thickening of the glomerular basement membrane (GBM), albuminuria, tubulointerstitial fibrosis and progressive decline in renal function. In advanced stages, DKD may require treatments such as dialysis or kidney transplant to sustain life. Therefore, early detection and proactive management of diabetes and its complications are crucial in preventing DKD and preserving kidney function.

Lipid metabolism disorder in diabetic kidney disease

Diabetic kidney disease (DKD), a significant complication associated with diabetes mellitus, presents limited treatment options. The progression of DKD is marked by substantial lipid disturbances, including alterations in triglycerides, cholesterol, sphingolipids, phospholipids, lipid droplets, and bile acids (BAs). Altered lipid metabolism serves as a crucial pathogenic mechanism in DKD, potentially intertwined with cellular ferroptosis, lipophagy, lipid metabolism reprogramming, and immune modulation of gut microbiota (thus impacting the liver-kidney axis). The elucidation of these mechanisms opens new potential therapeutic pathways for DKD management. This research explores the link between lipid metabolism disruptions and DKD onset.

Unveiling the Anti-Cholera and Active Diabetic Renoprotective Compounds of Maqian Essential Oil: A Computational and Molecular Dynamics Study

Cholera is an exceptionally aggressive infectious disease characterized by the potential to induce acute, copious, watery diarrhea of considerable severity and renal inflammation. Diabetic nephropathy is a serious complication of diabetes mellitus that can lead to kidney failure through inflammation; thus, anti-inflammatory agents are promising therapies for diabetic nephropathy. Previous studies have shown that the essential oil of Zanthoxylum myriacanthum var. pubescens Huang, Maqian essential oil (MQEO), exhibits potent antibacterial, anti-inflammatory, and renoprotective activities in diabetic mice and has emerged as a potential therapeutic drug for the treatment of diabetic nephropathy complications. Therefore, the present study was carried out to screen the potential inhibition of cholera toxin and the diabetic renoprotective activity of MQEO through computational approaches. Twelve chemical constituents derived from MQEO were docked with cholera toxin and the target proteins involved in diabetic nephropathy, namely, TXNIP, Nrf2, and DPP IV, and, subsequently, the predictions of molecular dynamic simulations, the drug-likeness properties, and the ADMET properties were performed. α-terpineol showed high binding affinities toward the cholera toxin protein. For TXNIP, among all the chemical constituents, α-phellandrene and p-cymene showed strong binding affinities with the TXNIP protein and displayed relatively stable flexibility at the hinge regions of the protein, favorable physicochemical properties in the absence of hepatotoxicity, and low cytotoxicity. For Nrf2, α-terpineol exhibited the highest binding affinity and formed a very stable complex with Nrf2, which displayed high pharmacokinetic properties. All compounds had low free-binding energies when docked with the DPP IV protein, which suggests potent biological activity. In conclusion, based on a computational approach, our findings reveal that MQEO constituents have inhibitory activity against cholera toxin and are promising therapeutic agents for suppressing diabetic inflammation and for the treatment of diabetic nephropathy complications.

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.

Dipeptidyl peptidase-4 inhibitor-related renal disease

BACKGROUND

Dipeptidyl peptidase-4 (DPP-4) inhibitors are widely used to treat type 2 diabetes (T2D). Lowering blood glucose is expected also to reduce the progression of diabetic nephropathy. We experienced a patient with T2D who achieved good glycemic control with a DPP-4 inhibitor but experienced rapid deterioration of renal function. Therefore, we performed a retrospective study of similar patients treated at our hospital.

METHODS

Out of 56 patients with biopsy-proven diabetic nephropathy who underwent native kidney biopsy at Toranomon Hospital from January 2018 through December 2022, we selected 22 patients who had been receiving DPP-4 inhibitors for at least 9 months at the time of kidney biopsy. Of these patients, we evaluated 16 diagnosed with class IIa diabetic nephropathy according to Tervaert's pathologic classification. The yearly estimated glomerular filtration rate (eGFR) slope in the 16 patients was arranged from the highest to the lowest slope. Ten patients with a large eGFR slope had thrombotic microangiopathy (TMA)-like lesions characterized by glomerular endothelial cell proliferation and GBM duplication on kidney biopsy (group A), whereas the remaining 6 patients did not have TMA-like lesions (group B).

RESULTS

Group A had a median (interquartile range [IQR]) eGFR of 18.2 (16.2, 26.2) and a yearly median (IQR) eGFR slope of -11.2 (-17.6, -9.2) mL/min/1.73 m2 after of DPP-4 administration, whereas group B had a median (IQR) eGFR of 31.5 (21.9, 34.8) mL/min/1.73 m2 and a yearly median (IQR) eGFR slope of -1.6 (-3.1, -0.3). Renal function declined significantly more rapidly in group A than in group B, and proteinuria was higher in group A than in group B (median [IQR], 3.4 [2.6, 4.4] g/day vs 0.8 [0.4, 1.3] g/day, respectively). Five patients in group A progressed to dialysis during follow-up, but none of the patients in group B did. Median (IQR) hemoglobin A1c was 6.2 % (6.0 %, 6.6 %) in group A and 5.8 % (5.7 %, 6.6 %) in group B.

CONCLUSION

DPP-4 inhibitors promote vascular endothelial regeneration, but when this effect occurs in the glomerulus, glomerular endothelial cell proliferation leads to TMA-like lesions, which may cause an increase in proteinuria and rapid decline in renal function.

Comparative Effects of Glucose-Lowering Medications on Kidney Outcomes in Type 2 Diabetes: The GRADE Randomized Clinical Trial

Importance

Type 2 diabetes (T2D) is the leading cause of kidney disease in the US. It is not known whether glucose-lowering medications differentially affect kidney function.

Objective

To evaluate kidney outcomes in the Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness (GRADE) trial comparing 4 classes of glucose-lowering medications added to metformin for glycemic management in individuals with T2D.

Design, Setting, and Participants

A randomized clinical trial was conducted at 36 sites across the US. Participants included adults with T2D for less than 10 years, a hemoglobin A1c level between 6.8% and 8.5%, and estimated glomerular filtration rate (eGFR) greater than or equal to 60 mL/min/1.73 m2 who were receiving metformin treatment. A total of 5047 participants were enrolled between July 8, 2013, and August 11, 2017, and followed up for a mean of 5.0 years (range, 0-7.6 years). Data were analyzed from February 21, 2022, to March 27, 2023.

Interventions

Addition of insulin glargine, glimepiride, liraglutide, or sitagliptin to metformin, with the medication combination continued until the HbA1c was greater than 7.5%; thereafter, insulin was added to maintain glycemic control.

Main Outcomes and Measures

Chronic eGFR slope (change in eGFR between year 1 and trial end) and a composite kidney disease progression outcome (albuminuria, dialysis, transplant, or death due to kidney disease). Secondary outcomes included incident eGFR less than 60 mL/min/1.73 m2, 40% decrease in eGFR to less than 60 mL/min/1.73 m2, doubling of urine albumin-to-creatinine ratio (UACR) to 30 mg/g or greater, and progression of Kidney Disease Improving Global Outcomes stage. Analyses were intention-to-treat.

Results

Of the 5047 participants, 3210 (63.6%) were men. Baseline characteristics were mean (SD) age 57.2 (10.0) years; HbA1c 7.5% (0.5%); diabetes duration, 4.2 (2.7) years; body mass index, 34.3 (6.8); blood pressure 128.3/77.3 (14.7/9.9) mm Hg; eGFR 94.9 (16.8) mL/min/1.73 m2; and median UACR, 6.4 (IQR 3.1-16.9) mg/g; 2933 (58.1%) were treated with renin-angiotensin-aldosterone inhibitors. Mean chronic eGFR slope was -2.03 (95% CI, -2.20 to -1.86) mL/min/1.73 m2 per year for patients receiving sitagliptin; glimepiride, -1.92 (95% CI, -2.08 to -1.75) mL/min/1.73 m2 per year; liraglutide, -2.08 (95% CI, -2.26 to -1.90) mL/min/1.73 m2 per year; and insulin glargine, -2.02 (95% CI, -2.19 to -1.84) mL/min/1.73 m2 per year (P = .61). Mean composite kidney disease progression occurred in 135 (10.6%) patients receiving sitagliptin; glimepiride, 155 (12.4%); liraglutide, 152 (12.0%); and insulin glargine, 150 (11.9%) (P = .56). Most of the composite outcome was attributable to albuminuria progression (98.4%). There were no significant differences by treatment assignment in secondary outcomes. There were no adverse kidney events attributable to medication assignment.

Conclusions and Relevance

In this randomized clinical trial, among people with T2D and predominantly free of kidney disease at baseline, no significant differences in kidney outcomes were observed during 5 years of follow-up when a dipeptidyl peptidase 4 inhibitor, sulfonylurea, glucagonlike peptide 1 receptor agonist, or basal insulin was added to metformin for glycemic control.

Trial Registration

ClinicalTrials.gov Identifier: NCT01794143.

Soluble dipeptidyl peptidase-4 induces epithelial-mesenchymal transition through tumor growth factor-β receptor

BACKGROUND

Kidney fibrosis is the final manifestation of chronic kidney disease, a condition mainly caused by diabetic nephropathy. Persistent tissue damage leads to chronic inflammation and excessive deposition of extracellular matrix (ECM) proteins. Epithelial-mesenchymal transition (EMT) is involved in a variety of tissue fibrosis and is a process during which epithelial cells transform into mesenchymal-like cells and lose their epithelial functionality and characteristics Dipeptidyl peptidase-4 (DPP4) is widely expressed in tissues, especially those of the kidney and small intestine. DPP4 exists in two forms: a plasma membrane-bound and a soluble form. Serum-soluble DPP4 (sDPP4) levels are altered in many pathophysiological conditions. Elevated circulating sDPP4 is correlated with metabolic syndrome. Because the role of sDPP4 in EMT remains unclear, we examined the effect of sDPP4 on renal epithelial cells.

METHODS

The influences of sDPP4 on renal epithelial cells were demonstrated by measuring the expression of EMT markers and ECM proteins.

RESULTS

sDPP4 upregulated the EMT markers ACTA2 and COL1A1 and increased total collagen content. sDPP4 activated SMAD signaling in renal epithelial cells. Using genetic and pharmacological methods to target TGFBR, we observed that sDPP4 activated SMAD signaling through TGFBR in epithelial cells, whereas genetic ablation and treatment with TGFBR antagonist prevented SMAD signaling and EMT. Linagliptin, a clinically available DPP4 inhibitor, abrogated sDPP4-induced EMT.

CONCLUSIONS

This study indicated that sDPP4/TGFBR/SMAD axis leads to EMT in renal epithelial cells. Elevated circulating sDPP4 levels may contribute to mediators that induce renal fibrosis.

Novel Biomarkers of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a highly prevalent condition worldwide. It represents one of the most common complications arising from diabetes mellitus (DM) and is the leading cause of end-stage kidney disease (ESKD). Its development involves three fundamental components: the hemodynamic, metabolic, and inflammatory axes. Clinically, persistent albuminuria in association with a progressive decline in glomerular filtration rate (GFR) defines this disease. However, as these alterations are not specific to DKD, there is a need to discuss novel biomarkers arising from its pathogenesis which may aid in the diagnosis, follow-up, therapeutic response, and prognosis of the disease.

Diabetic Kidney Care Redefined with a New Way into Remission

Diabetic kidney disease has been a leading cause for end-stage kidney disease. Traditional methods to slow progression include tight glycemic control, blood pressure control, and use of renin-angiotensin axis inhibitors. Finerenone and sodium glucose co-transporters have shown proven benefit in diabetic kidney disease regression recently. Other potential targets for slowing the decline in diabetic kidney disease are transforming growth factor beta, endothelin antagonist, protein kinase C inhibitors, advanced glycation end product inhibition, Janus kinase-signal transducer and activator of transcription pathway inhibition, phosphodiesterase 3 or 5 inhibitors, and Rho kinase inhibitor. These targets are at various trial phases and so far, show promising results.

DPP4 as a Potential Candidate in Cardiovascular Disease

The rising prevalence of cardiovascular disease has become a global health concern. The occurrence of cardiovascular disease is the result of long-term interaction of many risk factors, one of which is diabetes. As a novel anti-diabetic drug, DPP4 inhibitor has been proven to be cardiovascular safe in five recently completed cardiovascular outcome trials. Accumulating studies suggest that DPP4 inhibitor has potential benefits in a variety of cardiovascular diseases, including hypertension, calcified aortic valve disease, coronary atherosclerosis, and heart failure. On the one hand, in addition to improving blood glucose control, DPP4 inhibitor is involved in controlling cardiovascular risk factors. On the other hand, DPP4 inhibitor directly regulates the occurrence and progression of cardiovascular diseases through a variety of mechanisms. In this review, we summarize the recent advances of DPP4 in cardiovascular disease, aiming to discuss DPP4 inhibitor as a potential option for cardiovascular therapy.

Schisandrin A from Schisandra chinensis Attenuates Ferroptosis and NLRP3 Inflammasome-Mediated Pyroptosis in Diabetic Nephropathy through Mitochondrial Damage by AdipoR1 Ubiquitination

Schisandra chinensis, as a Chinese functional food, is rich in unsaturated fatty acids, minerals, vitamins, and proteins. Hence, this study was intended to elucidate the effects and biological mechanism of Schisandrin A from Schisandra chinensis in DN. C57BL/6 mice were fed with a high-fat diet and then injected with streptozotocin (STZ). Human renal glomerular endothelial cells were stimulated with 20 mmol/L d-glucose for DN model. Schisandrin A presented acute kidney injury in mice of DN. Schisandrin A reduced oxidative stress and inflammation in model of DN. Schisandrin A reduced high glucose-induced ferroptosis and reactive oxygen species (ROS-)-mediated pyroptosis by mitochondrial damage in model of DN. Schisandrin A directly targeted AdipoR1 protein and reduced LPS+ATP-induced AdipoR1 ubiquitination in vitro model. Schisandrin A activated AdipoR1/AMPK signaling pathway and suppressed TXNIP/NLRP3 signaling pathway in vivo and in vitro model of DN. Conclusively, our study revealed that Schisandrin A from Schisandra chinensis attenuates ferroptosis and NLRP3 inflammasome-mediated pyroptosis in DN by AdipoR1/AMPK-ROS/mitochondrial damage. Schisandrin A is a possible therapeutic option for DN or other diabetes.

Omarigliptin/galangin combination mitigates lipopolysaccharide-induced neuroinflammation in rats: Involvement of glucagon-like peptide-1, toll-like receptor-4, apoptosis and Akt/GSK-3β signaling

AIMS

The objectives of this work were to assess the possibility of administration of omarigliptin and/or galangin to combat lipopolysaccharide (LPS)-induced neuroinflammation in rats and to explore the possible mechanisms that might contribute to their actions.

MATERIALS AND METHODS

In a rat model of LPS-induced neuroinflammation, the changes in the behavioral tests, biochemical parameters, and the histopathological picture were assessed.

KEY FINDINGS

Administration of either omarigliptin or galangin to LPS-injected rats was able to significantly improve the behavioral changes with restoration of the oxidant/antioxidant balance, decrement of toll-like receptor-4 levels, and amelioration of the neuroinflammation associated with inhibition of apoptosis and restoration of glucagon-like peptide-1 levels in the cerebral tissues. In addition, omarigliptin and/or galangin significantly reduced the levels of phospho-Akt and glycogen synthase kinase 3 beta (GSK-3β) and significantly increased the expression of beclin-1 in the cerebral tissues compared versus the group treated with LPS alone. As a result, these changes were positively reflected on the histopathological and the electron microscopic picture of the cerebral tissues. These beneficial effects were maximally evidenced in rats treated with omarigliptin/galangin combination relative to the use of either omarigliptin or galangin alone.

SIGNIFICANCE

Omarigliptin/galangin combination might be proposed as a promising therapeutic line for mitigation of the pathophysiologic events of LPS-induced neuroinflammation.

3D-QSAR-based pharmacophore determination and design of novel DPP-4 inhibitors

Background/Aim: Therapy of diabetes mellitus type 2 includes drugs that act as inhibitors of dipeptidyl peptidase 4 (DPP-4) enzyme. Several DPP-4 inhibitors are marketed today and although they have favourable safety profile and tolerability, they show moderate activity in controlling glycaemia. The 3D quantitative structure-activity relationship (3D-QSAR) methodology was employed in order to find pharmacophore responsible for good DPP-4 inhibitory activity and designed new compounds with enhanced activity. Methods: For 3D-QSAR model development, 48 compounds structurally related to sitagliptin were collected from ChEMBL database. Structures of all compounds were optimised in order to find the best 3D conformations prior to QSAR modelling. To establish correlation between structure and biological activity Partial Least Squares (PLS) regression method integrated in Pentacle software was used. Results: Parameters of internal and external validation (R2 = 0.80, Q2 = 0.64 and R2 pred = 0.610) confirmed reliability of developed QSAR model. Analysis of obtained structural descriptors enabled identification of key structural characteristics that influenced DPP-4 inhibitory activity. Based on that information, new compounds were designed, of which 35 compounds had a better predicted activity, compared to sitagliptin. Conclusion: This QSAR model can be used for DPP-4 inhibitory activity prediction of structurally related compounds and resulting pharmacophore contains information useful for optimisation and design of new DPP-4 inhibitors. Finally, authors propose designed compounds for further synthesis, in vitro and in vivo testing, as new potential DPP-4 inhibitors.