Linagliptin Limits High Glucose Induced Conversion of Latent to Active TGFß through Interaction with CIM6PR and Limits Renal Tubulointerstitial Fibronectin.
ABSTRACT: In addition to lowering blood glucose in patients with type 2 diabetes mellitus, dipeptidyl peptidase 4 (DPP4) inhibitors have been shown to be antifibrotic. We have previously shown that cation independent mannose-6-phosphate receptor (CIM6PR) facilitates the conversion of latent to active transforming growth factor β1 (GFß1) in renal proximal tubular cells (PTCs) and linagliptin (a DPP4 inhibitor) reduced this conversion with downstream reduction in fibronectin transcription.We wanted to demonstrate that linagliptin reduces high glucose induced interaction between membrane bound DPP4 and CIM6PR in vitro and demonstrate reduction in active TGFß mediated downstream effects in a rodent model of type 1 diabetic nephropathy independent of high glycaemic levels.We used human kidney 2 (HK2) cells and endothelial nitric oxide synthase knock out mice to explore the mechanism and antifibrotic potential of linagliptin independent of glucose lowering. Using a proximity ligation assay, we show that CIM6PR and DPP4 interaction was increased by high glucose and reduced by linagliptin and excess mannose-6-phosphate (M6P) confirming that linagliptin is operating through an M6P-dependent mechanism. In vivo studies confirmed these TGFß1 pathway related changes and showed reduced fibronectin, phosphorylated smad2 and phosphorylated smad2/3 (pSmad2/3) with an associated trend towards reduction in tubular atrophy, which was independent of glucose lowering. No reduction in albuminuria, glomerulosclerotic index or cortical collagen deposition was observed.Linagliptin inhibits activation of TGFß1 through a M6P dependent mechanism. However this in isolation is not sufficient to reverse the multifactorial nature of diabetic nephropathy.
Project description:Dipeptidyl-peptidase 4 (DPP4) is expressed by resident renal cells, including glomerular cells. DPP4 inhibitors (gliptins) exert albuminuria lowering effects, but the role of renal DPP4 as a pharmacological target has not been elucidated. To better understand the actions of gliptins, the effects of linagliptin on the behaviour of immortalized human podocytes and mesangial cells were evaluated.The expression of DPP4 was measured at both the mRNA and protein levels. The effects of linagliptin on DPP4 activity, cell growth and cell cycle progression were determined. The contribution of the stromal cell-derived factor-1- CXCR4/CXCR7 signalling pathways was evaluated by studying the effects of AMD3100 (a CXCR4 antagonist and CXCR7 agonist) alone and in combination with linagliptin. The contribution of ERK1/2 activation was analysed by studying the effects of the MAPK kinase 1/2 inhibitor AZD6244.DPP4 was highly expressed in podocytes. The activity of DPP4 and podocyte growth were reduced by linagliptin. The effects of sitagliptin on podocyte growth were similar to those of linagliptin, were associated with inhibition of cell proliferation and mimicked by AMD3100. Moreover, linagliptin and AMD3100 were found to have a synergistic interaction, whereas no interaction was seen between linagliptin and AZD6244.Our cultures of human glomerular cells represent a reliable system for investigating the actions of gliptins. Moreover, DPP4 contributes to the regulation of podocyte behaviour. Inhibition of DPP4 in podocytes could underlie the effects of linagliptin on glomerular cells.
Project description:Glucagon like peptide-1 (GLP-1) plays a vital role in glucose homeostasis and sustaining ?-cell function. Currently there are two major methods to enhance endogenous GLP-1 activity; inhibiting dipeptidyl peptidase-4 (DPP4) or activating G protein-coupled receptor 119 (GPR119). Here we describe and validate a novel dual-target compound, HBK001, which can both inhibit DPP4 and activate GPR119 ex and in vivo. We show that HBK001 can promote glucose-stimulated insulin secretion in mouse and human primary islets. A single administration of HBK001 in ICR mice can increase plasma incretins levels much more efficiently than linagliptin, a classic DPP4 inhibitor. Long-term treatment of HBK001 in KKAy mice can ameliorate hyperglycemia as well as improve glucose tolerance, while linagliptin fails to achieve such glucose-lowing effects despite inhibiting 95% of serum DPP4 activity. Moreover, HBK001 can increase first-phase insulin secretion in KKAy mice, suggesting a direct effect on islet ?-cells via GPR119 activation. Furthermore, HBK001 can improve islet morphology, increase ?-cell proliferation and up-regulate genes involved in improved ?-cell function. Thus, we have identified, designed and synthesized a novel dual-target compound, HBK001, which represents a promising therapeutic candidate for type 2 diabetes, especially for patients who are insensitive to current DPP4 inhibitors.
Project description:Dipeptidyl peptidase 4 (DPP4) inhibitors improve glycemic control in type 2 diabetes, however, their influence on the retinal neurovascular unit remains unclear.Vasculo- and neuroprotective effects were assessed in experimental diabetic retinopathy and high glucose-cultivated C. elegans, respectively. In STZ-diabetic Wistar rats (diabetes duration of 24 weeks), DPP4 activity (fluorometric assay), GLP-1 (ELISA), methylglyoxal (LC-MS/MS), acellular capillaries and pericytes (quantitative retinal morphometry), SDF-1a and heme oxygenase-1 (ELISA), HMGB-1, Iba1 and Thy1.1 (immunohistochemistry), nuclei in the ganglion cell layer, GFAP (western blot), and IL-1beta, Icam1, Cxcr4, catalase and beta-actin (quantitative RT-PCR) were determined. In C. elegans, neuronal function was determined using worm tracking software.Linagliptin decreased DPP4 activity by 77% and resulted in an 11.5-fold increase in active GLP-1. Blood glucose and HbA1c were reduced by 13% and 14% and retinal methylglyoxal by 66%. The increase in acellular capillaries was diminished by 70% and linagliptin prevented the loss of pericytes and retinal ganglion cells. The rise in Iba-1 positive microglia was reduced by 73% with linagliptin. In addition, the increase in retinal Il1b expression was decreased by 65%. As a functional correlate, impairment of motility (body bending frequency) was significantly prevented in C. elegans.Our data suggest that linagliptin has a protective effect on the microvasculature of the diabetic retina, most likely due to a combination of neuroprotective and antioxidative effects of linagliptin on the neurovascular unit.
Project description:AIMS/INTRODUCTION:To evaluate linagliptin prescribing in type 2 diabetes mellitus patients with different comorbidities, an expanded Japanese post-marketing surveillance also collected baseline data for patients initiating other glucose-lowering drugs. MATERIALS AND METHODS:Patients initiating linagliptin monotherapy were enrolled, then the next patient starting monotherapy with another glucose-lowering drug was enrolled (2012-2014). Baseline data were collected and analyzed by the Medical Dictionary for Regulatory Activities system organ class. Analyses were descriptive, and meaningful differences defined as absolute standardized difference >10%. RESULTS:Over 4,200 type 2 diabetes mellitus patients were enrolled. Most system-organ class comorbidities were more common in patients initiating linagliptin versus other glucose-lowering drugs, with meaningful differences observed for metabolism/nutritional (50.5 vs 45.5%, respectively), cardiac (12.2 vs 8.6%, respectively), vascular (56.4 vs 51.3%, respectively) and renal/urinary disorders (9.9 vs 5.7%, respectively). CONCLUSIONS:Expanding the linagliptin Japanese post-marketing surveillance revealed linagliptin prescribing to a type 2 diabetes mellitus population with more comorbidities versus other glucose-lowering drugs. Although such preferential prescribing might be expected, as linagliptin requires no dose adjustment or monitoring in renally or hepatically impaired patients, this innovative post-marketing surveillance approach generated important evidence that could only be shown in such a non-randomized comparative study. These data generated insights important for the design and interpretation of observational studies and spontaneous reports, which are key for public health.
Project description:BACKGROUND:Dipeptidyl peptidase 4 (DPP4) inhibitors improve glycemic control by promoting GLP1-mediated glucose-dependent insulin secretion and suppression of glucagon. Sitagliptin and vildagliptin have been shown to improve insulin sensitivity in patients with type 2 diabetes mellitus (T2DM). However, these patients had uncontrolled blood glucose at inclusion; therefore, the improvement in insulin sensitivity observed in these studies could be attributed to the drug per se and/or reduction in glucotoxicity. This study examines the effect of linagliptin on insulin sensitivity and ?-cell function in patients with well-controlled T2DM. METHODS:Thirty patients with T2DM of duration ?5 years, and having HbA1c <?7.5% were randomized to receive linagliptin, voglibose or placebo (n?=?10 each), and were followed up for 6 months. Insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp, and insulin secretory response was measured by basal (M0) and postprandial (M1) ?-cell function, and area under curve (AUC) for C-peptide during mixed meal tolerance test. RESULTS:The median HbA1c of the study subjects at inclusion was 6.9% and there was no significant difference among the groups in terms of age, duration of diabetes, body mass index (BMI), HbA1c, insulin sensitivity, AUC of C-peptide and M0 and M1 at baseline. At the end of the study, there was a modest reduction in HbA1c (-?0.2%) in the linagliptin group, and a significant decrease (-?0.8%) in the voglibose group, as compared to placebo (p?=?0.038). However, there were no significant differences in insulin sensitivity, M0 and M1 and AUC of C-peptide, within, or among the groups. CONCLUSION:Linagliptin modestly improves glycemic profile in patients with well controlled T2DM; however, it may not have an effect on insulin sensitivity in these patients. TRIAL REGISTRATION:Retrospectively Registered in Clinicaltrials.gov (ID number, NCT02097342 ). Registered: March 27, 2014.
Project description:Postprandial triglycerides (TGs) are elevated in people with type 2 diabetes (T2D). Glucose-lowering agents, such as glucagon-like peptide-1 (GLP-1) receptor agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors, also reduce postprandial TG excursion. Although the glucose-lowering mechanisms of DPP-4 have been extensively studied, how the reduction of DPP-4 activity improves lipid tolerance remains unclear. Here, we demonstrate that gut-selective and systemic inhibition of DPP-4 activity reduces postprandial TG excursion in young mice. Genetic inactivation of Dpp4 simultaneously within endothelial cells and hematopoietic cells using Tie2-Cre reduced intestinal lipoprotein secretion under regular chow diet conditions. Bone marrow transplantation revealed a key role for hematopoietic cells in modulation of lipid responses arising from genetic reduction of DPP-4 activity. Unexpectedly, deletion of Dpp4 in enterocytes increased TG excursion in high-fat diet-fed (HFD-fed) mice. Moreover, chemical reduction of DPP-4 activity and increased levels of GLP-1 were uncoupled from TG excursion in older or HFD-fed mice, yet lipid tolerance remained improved in older Dpp4-/- and Dpp4EC-/- mice. Taken together, this study defines roles for specific DPP-4 compartments, age, and diet as modifiers of DPP-4 activity linked to control of gut lipid metabolism.
Project description:CARdiovascular Outcome Trial of LINAgliptin Versus Glimepiride in Type 2 Diabetes (NCT01243424) is an ongoing, randomized trial in subjects with early type 2 diabetes and increased cardiovascular risk or established complications that will determine the long-term cardiovascular impact of linagliptin versus the sulphonylurea glimepiride. Eligible patients were sulphonylurea-naïve with HbA1c 6.5%-8.5% or previously exposed to sulphonylurea (in monotherapy or in a combination regimen <5?years) with HbA1c 6.5%-7.5%. Primary outcome is time to first occurrence of cardiovascular death, non-fatal myocardial infarction, non-fatal stroke or hospitalization for unstable angina. A total of 631 patients with primary outcome events will be required to provide 91% power to demonstrate non-inferiority in cardiovascular safety by comparing the upper limit of the two-sided 95% confidence interval as being below 1.3 for a given hazard ratio. Hierarchical testing for superiority will follow, and the trial has 80% power to demonstrate a 20% relative cardiovascular risk reduction. A total of 6041 patients were treated with median type 2 diabetes duration 6.2?years, 40.0% female, mean HbA1c 7.2%, 66% on 1 and 24% on 2 glucose-lowering agents and 34.5% had previous cardiovascular complications. The results of CARdiovascular Outcome Trial of LINAgliptin Versus Glimepiride in Type 2 Diabetes may influence the decision-making process for selecting a second glucose-lowering agent after metformin in type 2 diabetes.
Project description:Type 2 diabetes mellitus is an epidemic in Asia, yet clinical trials of glucose-lowering therapies often enroll predominantly Western populations. We explored the initial combination of metformin and linagliptin, a dipeptidyl peptidase-4 inhibitor, in newly diagnosed type 2 diabetes mellitus patients in Asia with marked hyperglycemia.This was a post-hoc subgroup analysis of a multinational, parallel-group clinical trial in which 316 newly diagnosed type 2 diabetes mellitus patients with glycated hemoglobin A1c (HbA1c) 8.5-12.0% were randomized to double-blind oral treatment with linagliptin/metformin or linagliptin monotherapy. The primary end-point was the change from baseline in HbA1c at week 24. We evaluated data for the 125 participants from Asian countries.After 24 weeks, the mean ± standard error reduction from baseline in HbA1c (mean 10.0%) was -2.99 ± 0.18% with linagliptin/metformin and -1.84 ± 0.18% with linagliptin; a treatment difference of -1.15% (95% confidence interval -1.65 to -0.66, P < 0.0001). HbA1c <7.0% was achieved by 60% of participants receiving linagliptin/metformin. The mean bodyweight change after 24 weeks was -0.45 ± 0.41 kg and 1.33 ± 0.45 kg in the linagliptin/metformin and linagliptin groups, respectively (treatment difference -1.78 kg [95% confidence interval -2.99 to -0.57, P = 0.0043]). Drug-related adverse events occurred in 9.7% of participants receiving linagliptin/metformin and 4.8% of those receiving linagliptin. Hypoglycemia occurred in 6.5% and 4.8% of the linagliptin/metformin and linagliptin groups, respectively, with no severe episodes. Gastrointestinal disorders occurred in 12.9% and 12.7% of the linagliptin/metformin and linagliptin groups, respectively, with no associated treatment discontinuations.In people from Asia with newly diagnosed type 2 diabetes mellitus and marked hyperglycemia, the initial combination of linagliptin and metformin substantially improved glycemic control without weight gain and with infrequent hypoglycemia. Initial oral combination therapy might be a viable treatment for such individuals.
Project description:We have shown that glycemic control with metformin or endothelin-1 (ET-1) inhibition with bosentan prevents and restores diabetes-mediated cerebral pathological remodeling and neovascularization. Our recent data suggest that linagliptin, a member of the dipeptidyl peptidase-4 inhibitor class of glucose-lowering agents, prevents cerebrovascular remodeling and dysfunction independent of its blood glucose lowering effects. We hypothesized that linagliptin prevents pathological neovascularization via the modulation of the ET-1 system.24-week old diabetic Goto-Kakizaki and nondiabetic Wistar rats were treated for 4weeks with either vehicle chow or chow containing 166mg/kg linagliptin. At termination, FITC-dextran was injected to visualize the vasculature. Brain sections were imaged by confocal microscopy for vascular density, tortuosity, vascular volume, and surface in both the cortex and striatum. Retinal acellular capillary formation was measured. Brain microvascular endothelial cells (BMVEC) isolated from control or diabetic rats were treated with linagliptin with or without ET-1 dual receptor antagonist and tested for angiogenic properties with cell migration and tube formation assays.Linagliptin reduced all indices of cerebral neovascularization compared with control rats. In vitro, linagliptin normalized the augmented angiogenic properties of BMVECs isolated from diabetic animals and bosentan reversed this response. Cells from diabetic animals had higher ET-1 and less ETB receptors than in control cells. Linagliptin significantly decreased ET-1 levels and increased ETB receptors.ET system contributes to pathological neovascularization in diabetes as evidenced by restoration of functional angiogenesis by bosentan treatment and prevention of linagliptin-mediated improvement of angiogenesis in the in vitro model.
Project description:Dipeptidyl peptidase-4 (Dpp4) inhibitors are used worldwide to combat diabetes, however, their roles in cardiovascular disorders are yet to be defined. Here we show that a DPP4 inhibitor, linagliptin, contributes for the suppression of capillary rarefaction in cardiac tissues of dietary obese mice model. Imposing a high fat diet into mice induced capillary rarefaction and cardiac dysfunction. These pathologies associated with high DPP4 level in circulation, and the administration of linagliptin into dietary obese mice suppressed the development of capillary rarefaction and ameliorated cardiac dysfunction. Early growth response protein 1 (EGR1), known as an angiogenic transcription factor, is significantly reduced in the cardiac tissue upon metabolic stress, and this suppression was inhibited by the administration of linagliptin. Overall design: Total RNA of cardiac tissue was obtained from a normal chow- and a high-fat diet-fed mice with or without a DPP-4 inhibitor. Mice were fed a high-fat diet or a normal chow for totally 8 weeks from 4 weeks age, and analyzed at 12 weeks of age.The DPP-4 inhibitor was administered within a water at the concentration of 10 mg/kg/day for 8 weeks since 4 weeks of age.