Drugs for Diabetes: From Pharmacology to Clinical Application.

Type I and type II diabetes mellitus, characterized by increased blood glucose levels, affect almost half a billion people around the world [...].

Loss of endothelial glucocorticoid receptor accelerates organ fibrosis in db/db mice.

Endothelial cells play a key role in maintaining homeostasis and are deranged in many disease processes, including fibrotic conditions. Absence of the endothelial glucocorticoid receptor (GR) has been shown to accelerate diabetic kidney fibrosis in part through upregulation of Wnt signaling. The db/db mouse model is a model of spontaneous type 2 diabetes that has been noted to develop fibrosis in multiple organs over time, including the kidneys. This study aimed to determine the effect of loss of endothelial GR on organ fibrosis in the db/db model. db/db mice lacking endothelial GR showed more severe fibrosis in multiple organs compared with endothelial GR-replete db/db mice. Organ fibrosis could be substantially improved either through administration of a Wnt inhibitor or metformin. IL-6 is a key cytokine driving the fibrosis phenotype and is mechanistically linked to Wnt signaling. The db/db model is an important tool to study the mechanisms of fibrosis and its phenotype in the absence of endothelial GR highlights the synergistic effects of Wnt signaling and inflammation in the pathogenesis or organ fibrosis.NEW & NOTEWORTHY The major finding of this work is that endothelial glucocorticoid receptor-mediated upregulation of Wnt signaling and concurrent hyperinflammation work synergistically to exacerbate organ fibrosis in a genetic mouse model of diabetes. This study adds to our understanding of diabetic renal fibrosis and has important implications for the use of metformin in this condition.

Loss of endothelial glucocorticoid receptor accelerates organ fibrosis in db/db mice.

Endothelial cells play a key role in maintaining homeostasis and are deranged in many disease processes, including fibrotic conditions. Absence of the endothelial glucocorticoid receptor (GR) has been shown to accelerate diabetic kidney fibrosis in part through up regulation of Wnt signaling. The db/db mouse model is a model of spontaneous type 2 diabetes that has been noted to develop fibrosis in multiple organs over time, including the kidneys. This study aimed to determine the effect of loss of endothelial GR on organ fibrosis in the db/db model. Db/Db mice lacking endothelial GR showed more severe fibrosis in multiple organs compared to endothelial GR-replete db/db mice. Organ fibrosis could be substantially improved either through administration of a Wnt inhibitor or metformin. IL-6 is a key cytokine driving the fibrosis phenotype and is mechanistically linked to Wnt signaling. The db/db model is an important tool to study mechanisms of fibrosis and its phenotype in the absence of endothelial GR highlights the synergistic effects of Wnt signaling and inflammation in the pathogenesis or organ fibrosis.

Identification of 3-((1-(Benzyl(2-hydroxy-2-phenylethyl)amino)-1-oxo-3-phenylpropan-2-yl)carbamoyl)pyrazine-2-carboxylic Acid as a Potential Inhibitor of Non-Nucleosidase Reverse Transcriptase Inhibitors through InSilico Ligand- and Structure-Based Approaches.

Non-nucleosidase reverse transcriptase inhibitors (NNRTIs) are highly promising agents for use in highly effective antiretroviral therapy. We implemented a rational approach for the identification of promising NNRTIs based on the validated ligand- and structure-based approaches. In view of our state-of-the-art techniques in drug design and discovery utilizing multiple modeling approaches, we report here, for the first time, quantitative pharmacophore modeling (HypoGen), docking, and in-house database screening approaches in the identification of potential NNRTIs. The validated pharmacophore model with three hydrophobic groups, one aromatic ring group, and a hydrogen-bond acceptor explains the interactions at the active site by the inhibitors. The model was implemented in pharmacophore-based virtual screening (in-house and commercially available databases) and molecular docking for prioritizing the potential compounds as NNRTI. The identified leads are in good corroboration with binding affinities and interactions as compared to standard ligands. The model can be utilized for designing and identifying the potential leads in the area of NNRTIs.

Coronavirus Disease (COVID)-19 and Diabetic Kidney Disease.

The present review describes COVID-19 severity in diabetes and diabetic kidney disease. We discuss the crucial effect of COVID-19-associated cytokine storm and linked injuries and associated severe mesenchymal activation in tubular epithelial cells, endothelial cells, and macrophages that influence neighboring cell homeostasis, resulting in severe proteinuria and organ fibrosis in diabetes. Altered microRNA expression disrupts cellular homeostasis and the renin-angiotensin-system, targets reno-protective signaling proteins, such as angiotensin-converting enzyme 2 (ACE2) and MAS1 receptor (MAS), and facilitates viral entry and replication in kidney cells. COVID-19-associated endotheliopathy that interacts with other cell types, such as neutrophils, platelets, and macrophages, is one factor that accelerates prethrombotic reactions and thrombus formation, resulting in organ failures in diabetes. Apart from targeting vital signaling through ACE2 and MAS, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections are also associated with higher profibrotic dipeptidyl transferase-4 (DPP-4)-mediated mechanisms and suppression of AMP-activated protein kinase (AMPK) activation in kidney cells. Lowered DPP-4 levels and restoration of AMPK levels are organ-protective, suggesting a pathogenic role of DPP-4 and a protective role of AMPK in diabetic COVID-19 patients. In addition to standard care provided to COVID-19 patients, we urgently need novel drug therapies that support the stability and function of both organs and cell types in diabetes.

Podocyte Glucocorticoid Receptors Are Essential for Glomerular Endothelial Cell Homeostasis in Diabetes Mellitus.

Background Proteinuria and glomerular segmental fibrosis are inevitable complications of diabetic nephropathy though their mechanisms are poorly understood. Understanding the clinical characteristics and pathogenesis of proteinuria and glomerular segmental fibrosis in diabetic nephropathy is, therefore, urgently needed for patient management of this severe disease. Methods and Results Diabetes mellitus was induced in podocyte-specific glucocorticoid receptor knockout (GRPKO) mice and control littermates by administration of streptozotocin. Primary podocytes were isolated and subjected to analysis of Wnt signaling and fatty acid metabolism. Conditioned media from primary podocytes was transferred to glomerular endothelial cells. Histologic analysis of kidneys from diabetic GRPKO mice showed worsened fibrosis, increased collagen deposition, and glomerulomegaly indicating severe glomerular fibrosis. Higher expression of transforming growth factor-ßR1 and ß-catenin and suppressed expression of carnitine palmitoyltransferase 1A in nephrin-positive cells were found in the kidneys of diabetic GRPKO mice. Podocytes isolated from diabetic GRPKO mice demonstrated significantly higher profibrotic gene expression and suppressed fatty acid oxidation compared with controls. Administration of a Wnt inhibitor significantly improved the fibrotic features in GRPKO mice. The glomerular endothelium of diabetic GRPKO mice demonstrated the features of endothelial-to-mesenchymal transition. Moreover, endothelial cells treated with conditioned media from podocytes lacking GR showed increased expression of α-smooth muscle actin, transforming growth factor-ßR1 and ß-catenin levels. Conclusions These data demonstrate that loss of podocyte GR leads to upregulation of Wnt signaling and disruption in fatty acid metabolism. Podocyte-endothelial cell crosstalk, mediated through GR, is important for glomerular homeostasis, and its disruption likely contributes to diabetic nephropathy.

Interactions among Long Non-Coding RNAs and microRNAs Influence Disease Phenotype in Diabetes and Diabetic Kidney Disease.

Large-scale RNA sequencing and genome-wide profiling data revealed the identification of a heterogeneous group of noncoding RNAs, known as long noncoding RNAs (lncRNAs). These lncRNAs play central roles in health and disease processes in diabetes and cancer. The critical association between aberrant expression of lncRNAs in diabetes and diabetic kidney disease have been reported. LncRNAs regulate diverse targets and can function as sponges for regulatory microRNAs, which influence disease phenotype in the kidneys. Importantly, lncRNAs and microRNAs may regulate bidirectional or crosstalk mechanisms, which need to be further investigated. These studies offer the novel possibility that lncRNAs may be used as potential therapeutic targets for diabetes and diabetic kidney diseases. Here, we discuss the functions and mechanisms of actions of lncRNAs, and their crosstalk interactions with microRNAs, which provide insight and promise as therapeutic targets, emphasizing their role in the pathogenesis of diabetes and diabetic kidney disease.

Endothelial SIRT3 regulates myofibroblast metabolic shifts in diabetic kidneys.

Defects in endothelial cells cause deterioration in kidney function and structure. Here, we found that endothelial SIRT3 regulates metabolic reprogramming and fibrogenesis in the kidneys of diabetic mice. By analyzing, gain of function of the SIRT3 gene by overexpression in a fibrotic mouse strain conferred disease resistance against diabetic kidney fibrosis, whereas its loss of function in endothelial cells exacerbated the levels of diabetic kidney fibrosis. Regulation of endothelial cell SIRT3 on fibrogenic processes was due to tight control over the defective central metabolism and linked activation of endothelial-to-mesenchymal transition (EndMT). SIRT3 deficiency in endothelial cells stimulated the TGFß/Smad3-dependent mesenchymal transformations in renal tubular epithelial cells. These data demonstrate that SIRT3 regulates defective metabolism and EndMT-mediated activation of the fibrogenic pathways in the diabetic kidneys. Together, our findings show that endothelial SIRT3 is a fundamental regulator of defective metabolism regulating health and disease processes in the kidney.

Loss of endothelial glucocorticoid receptor accelerates diabetic nephropathy.

Endothelial cells play a key role in the regulation of disease. Defective regulation of endothelial cell homeostasis may cause mesenchymal activation of other endothelial cells or neighboring cell types, and in both cases contributes to organ fibrosis. Regulatory control of endothelial cell homeostasis is not well studied. Diabetes accelerates renal fibrosis in mice lacking the endothelial glucocorticoid receptor (GR), compared to control mice. Hypercholesterolemia further enhances severe renal fibrosis. The fibrogenic phenotype in the kidneys of diabetic mice lacking endothelial GR is associated with aberrant cytokine and chemokine reprogramming, augmented Wnt signaling and suppression of fatty acid oxidation. Both neutralization of IL-6 and Wnt inhibition improve kidney fibrosis by mitigating mesenchymal transition. Conditioned media from endothelial cells from diabetic mice lacking endothelial GR stimulate Wnt signaling-dependent epithelial-to-mesenchymal transition in tubular epithelial cells from diabetic controls. These data demonstrate that endothelial GR is an essential antifibrotic molecule in diabetes.

Pharmacophore modeling, docking and the integrated use of a ligand- and structure-based virtual screening approach for novel DNA gyrase inhibitors: synthetic and biological evaluation studies.

Fluoroquinolones, a class of compound, act via inhibiting DNA gyrase and topoisomerase IV enzymes. This is an important class of drugs with high success rates for the treatment of tuberculosis and other bacterial infections. An indirect drug design approach was used to develop a meaningful pharmacophore model using the HypoGen module of Discovery Studio 2.0 on a set of 27 structurally diverse compounds with a wide range of biological activity (5 log units). The best hypothesis had three hydrogen bond acceptors (HBA) and one hydrophobic (Hy) moiety, showing r = 0.95, and it predicts the test set of 44 compounds well, with r 2 = 0.823. The same features (acceptor and hydrophobic functionality) were validated at the binding site of the DNA gyrase active site using GOLD version 3.0.1 and Molegro Virtual Docker, which showed corresponding hydrogen bond interactions and also π-π stacking interactions that correlated well with the PIC50 values (r 2 = 0.6142). The thoroughly validated model was used to screen an extensive database of 0.25 million compounds to identify potential leads. The validated model was implemented for the identification, design, synthesis, and biological evaluation of leads. Ten new chemical entities were synthesized based on our scaffold hopping techniques from the identified virtual screening and tested against the tuberculosis bacterium to obtain preliminary MIC values. The results showed that 3 out of 10 synthesized compounds exhibited good MICs, from 1.25 to 50 µM. This proves the robustness and applicability of the developed model, which is a promising tool for identifying new topoisomerase II inhibitors for the treatment of tuberculosis.

Loss of Mitochondrial Control Impacts Renal Health.

Disruption of mitochondrial biosynthesis or dynamics, or loss of control over mitochondrial regulation leads to a significant alteration in fuel preference and metabolic shifts that potentially affect the health of kidney cells. Mitochondria regulate metabolic networks which affect multiple cellular processes. Indeed, mitochondria have established themselves as therapeutic targets in several diseases. The importance of mitochondria in regulating the pathogenesis of several diseases has been recognized, however, there is limited understanding of mitochondrial biology in the kidney. This review provides an overview of mitochondrial dysfunction in kidney diseases. We describe the importance of mitochondria and mitochondrial sirtuins in the regulation of renal metabolic shifts in diverse cells types, and review this loss of control leads to increased cell-to-cell transdifferentiation processes and myofibroblast-metabolic shifts, which affect the pathophysiology of several kidney diseases. In addition, we examine mitochondrial-targeted therapeutic agents that offer potential leads in combating kidney diseases.

Endothelial FGFR1 (Fibroblast Growth Factor Receptor 1) Deficiency Contributes Differential Fibrogenic Effects in Kidney and Heart of Diabetic Mice.

Endothelial-to-mesenchymal transition (EndMT) has been shown to contribute to organ fibrogenesis. We have reported that N-acetyl-seryl-aspartyl- lysyl-proline (AcSDKP) restored levels of diabetes mellitus-suppressed FGFR1 (fibroblast growth factor receptor 1), the endothelial receptor essential for combating EndMT. However, the molecular regulation and biological/pathological significance of the AcSDKP-FGFR1 relationship has not been elucidated yet. Here, we demonstrated that endothelial FGFR1 deficiency led to AcSDKP-resistant EndMT and severe fibrosis associated with EndMT-stimulated fibrogenic programming in neighboring cells. Diabetes mellitus induced severe kidney fibrosis in endothelial FGFR1-deficient mice (FGFR1fl/fl; VE-cadherin-Cre: FGFR1EKO) but not in control mice (FGFR1fl/fl); AcSDKP completely or partially suppressed kidney fibrosis in control or FGFR1EKO mice. Severe fibrosis was also induced in hearts of diabetic FGFR1EKO mice; however, AcSDKP had no effect on heart fibrosis in FGFR1EKO mice. AcSDKP also had no effect on EndMT in either kidney or heart but partially suppressed epithelial-to-mesenchymal transition in kidneys of diabetic FGFR1EKO mice. The medium from FGFR1-deficient endothelial cells stimulated TGFß (transforming growth factor ß)/Smad-dependent epithelial-to-mesenchymal transition in cultured human proximal tubule epithelial cell line, AcSDKP inhibited such epithelial-to-mesenchymal transition. These data demonstrated that endothelial FGFR1 is essential as an antifibrotic core molecule as the target of AcSDKP.

Cancer Biology and Prevention in Diabetes.

The available evidence suggests a complex relationship between diabetes and cancer. Epidemiological data suggest a positive correlation, however, in certain types of cancer, a more complex picture emerges, such as in some site-specific cancers being specific to type I diabetes but not to type II diabetes. Reports share common and differential mechanisms which affect the relationship between diabetes and cancer. We discuss the use of antidiabetic drugs in a wide range of cancer therapy and cancer therapeutics in the development of hyperglycemia, especially antineoplastic drugs which often induce hyperglycemia by targeting insulin/IGF-1 signaling. Similarly, dipeptidyl peptidase 4 (DPP-4), a well-known target in type II diabetes mellitus, has differential effects on cancer types. Past studies suggest a protective role of DPP-4 inhibitors, but recent studies show that DPP-4 inhibition induces cancer metastasis. Moreover, molecular pathological mechanisms of cancer in diabetes are currently largely unclear. The cancer-causing mechanisms in diabetes have been shown to be complex, including excessive ROS-formation, destruction of essential biomolecules, chronic inflammation, and impaired healing phenomena, collectively leading to carcinogenesis in diabetic conditions. Diabetes-associated epithelial-to-mesenchymal transition (EMT) and endothelial-to-mesenchymal transition (EndMT) contribute to cancer-associated fibroblast (CAF) formation in tumors, allowing the epithelium and endothelium to enable tumor cell extravasation. In this review, we discuss the risk of cancer associated with anti-diabetic therapies, including DPP-4 inhibitors and SGLT2 inhibitors, and the role of catechol-o-methyltransferase (COMT), AMPK, and cell-specific glucocorticoid receptors in cancer biology. We explore possible mechanistic links between diabetes and cancer biology and discuss new therapeutic approaches.

Metabolic reprogramming by N-acetyl-seryl-aspartyl-lysyl-proline protects against diabetic kidney disease.

BACKGROUND AND PURPOSE: ACE inhibitors (ACEIs) and AT1 receptor antagonists (ARBs) are first-line drugs that are believed to reduce the progression of end-stage renal disease in diabetic patients. Differences in the effects of ACEIs and ARBs are not well studied and the mechanisms responsible are not well understood. EXPERIMENTAL APPROACH: Male diabetic CD-1 mice were treated with ACEI, ARB, N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP), ACEI + AcSDKP, ARB + AcSDKP, glycolysis inhibitors or non-treatment. Moreover, prolyl oligopeptidase inhibitor (POPi)-injected male diabetic C57Bl6 mice were treated with ACEI, AcSDKP and ARB or non-treatment. Western blot and immunofluorescent staining were used to examine key enzymes and regulators of central metabolism. KEY RESULTS: The antifibrotic action of ACEI imidapril is due to an AcSDKP-mediated antifibrotic mechanism, which reprograms the central metabolism including restoring SIRT3 protein and mitochondrial fatty acid oxidation and suppression of abnormal glucose metabolism in the diabetic kidney. Moreover, the POPi S17092 significantly blocked the AcSDKP synthesis, accelerated kidney fibrosis and disrupted the central metabolism. ACEI partly restored the kidney fibrosis and elevated the AcSDKP level, whereas the ARB (TA-606) did not show such effects in the POPi-injected mice. ACE inhibition and AcSDKP suppressed defective metabolism-linked mesenchymal transformations and reduced collagen-I and fibronectin accumulation in the diabetic kidneys. CONCLUSION AND IMPLICATIONS: The study envisages that AcSDKP is the endogenous antifibrotic mediator that controls the metabolic switch between glucose and fatty acid metabolism and that suppression of AcSDKP leads to disruption of kidney cell metabolism and activates mesenchymal transformations leading to severe fibrosis in the diabetic kidney.

Renal protective effects of empagliflozin via inhibition of EMT and aberrant glycolysis in proximal tubules.

Sodium glucose cotransporter 2 (SGLT2) inhibitors are beneficial in halting diabetic kidney disease; however, the complete mechanisms have not yet been elucidated. The epithelial-mesenchymal transition (EMT) is associated with the suppression of sirtuin 3 (Sirt3) and aberrant glycolysis. Here, we hypothesized that the SGLT2 inhibitor empagliflozin restores normal kidney histology and function in association with the inhibition of aberrant glycolysis in diabetic kidneys. CD-1 mice with streptozotocin-induced diabetes displayed kidney fibrosis that was associated with the EMT at 4 months after diabetes induction. Empagliflozin intervention for 1 month restored all pathological changes; however, adjustment of blood glucose by insulin did not. Empagliflozin normalized the suppressed Sirt3 levels and aberrant glycolysis that was characterized by HIF-1α accumulation, hexokinase 2 induction, and pyruvate kinase isozyme M2 dimer formation in diabetic kidneys. Empagliflozin also suppressed the accumulation of glycolysis byproducts in diabetic kidneys. Another SGLT2 inhibitor, canagliflozin, demonstrated similar in vivo effects. High-glucose media induced the EMT, which was associated with Sirt3 suppression and aberrant glycolysis induction, in the HK2 proximal tubule cell line; SGLT2 knockdown suppressed the EMT, with restoration of all aberrant functions. SGLT2 suppression in tubular cells also inhibited the mesenchymal transition of neighboring endothelial cells. Taken together, SGLT2 inhibitors exhibit renoprotective potential that is partially dependent on the inhibition of glucose reabsorption and subsequent aberrant glycolysis in kidney tubules.