PPAR agonists: multimodal drugs for the treatment of type-2 diabetes

Inverse Agonists of Peroxisome Proliferator-Activated Receptor Gamma: Advances and Prospects in Cancer Treatment

Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-dependent nuclear transcription factor that modulates metabolic homeostasis and cell proliferation. Inverse agonism of PPARγ is an emerging anticancer strategy, particularly for the treatment of bladder cancer. The first-in-class PPARγ inverse agonist, FX-909, is currently being studied in clinical trials for cancer treatment. However, PPARγ inverse agonists are still in the early stages of development. The discovery of compounds with novel chemical structures, potent efficacy, and favorable pharmacokinetic properties is urgently needed. In this perspective, the biological functions of PPARγ and its role in cancer pathology are introduced, and currently available PPARγ inverse agonists and their preliminary structure-activity relationships (SARs) are discussed from a medicinal chemistry viewpoint. These findings inform the development of anticancer agents that act as PPARγ inverse agonists. Furthermore, our discussion of the complex biological functions of PPARγ provides insights into the exploration of its role in various diseases.

Protective Effect of Semaglutide on Obesity-Induced Renal Disease and Obesity-Induced Kidney Renal Clear Cell Carcinoma

Purpose

Proteomics was used to study the effect of semaglutide on the expression of renal protein in obese mice, and looking for proteins that could improve the prognosis of Kidney Renal Clear Cell Carcinoma (KIRC).

Materials and Methods

Thirty-six mice were randomly divided into normal-fat diet group (NFD), high-fat diet group (HFD), high-fat diet plus semaglutide intervention group (HS). Collected mice serum, urine, kidney tissue samples, and detected urinary protein/creatinine, blood glucose, blood lipid, inflammation, oxidative stress and other related indicators. Different staining methods were used to analyze the pathological changes of mice's kidneys. Liquid chromatography-tandem mass spectrometry mass spectrometry (LC-MS/MS) analysis was used to analyze the total protein in the kidneys of mice. Finally, bioinformatics technology was used to analyze significantly different expressed proteins (DEPs).

Results

The mechanism of semaglutide protecting the kidneys were related to oxidative phosphorylation, PPAR signaling pathway, thiamine, butyric acid and tryptophan metabolism pathways. Moreover, semaglutide could significantly increase the expression of Man1a1 and Ntn4 in the kidneys of mice, while the high-expression of Man1a1 and Ntn4 in KIRC population had a better overall survival rate.

Conclusion

Semaglutide could regulate the development of KIRC by up-adjusting the expression of Man1a1 and Ntn4.

Predictive modelling of peroxisome proliferator-activated receptor gamma (PPARγ) IC50 inhibition by emerging pollutants using light gradient boosting machine

Peroxisome proliferator-activated receptor gamma (PPARγ), a critical nuclear receptor, plays a pivotal role in regulating metabolic and inflammatory processes. However, various environmental contaminants can disrupt PPARγ function, leading to adverse health effects. This study introduces a novel approach to predict the inhibitory activity (IC50 values) of 140 chemical compounds across 13 categories, including pesticides, organochlorines, dioxins, detergents, flame retardants, and preservatives, on PPARγ. The predictive model, based on the light-gradient boosting machine (LightGBM) algorithm, was trained on a dataset of 1804 molecules showed r2 values of 0.82 and 0.59, Mean Absolute Error (MAE) of 0.38 and 0.58, and Root Mean Square Error (RMSE) of 0.54 and 0.76 for the training and test sets, respectively. This study provides novel insights into the interactions between emerging contaminants and PPARγ, highlighting the potential hazards and risks these chemicals may pose to public health and the environment. The ability to predict PPARγ inhibition by these hazardous contaminants demonstrates the value of this approach in guiding enhanced environmental toxicology research and risk assessment.

Exploring fingerprints for antidiabetic therapeutics related to peroxisome proliferator-activated receptor gamma (PPARγ) modulators: A chemometric modeling approach

This study demonstrated the correlation of molecular structures of Peroxisome proliferator-activated receptor gamma (PPARγ) modulators and their biological activities. Bayesian classification, and recursive partitioning (RP) studies have been applied to a dataset of 323 PPARγ modulators with diverse scaffolds. The results provide a deep insight into the important sub-structural features modulating PPARγ. The molecular docking analysis again confirmed the significance of the identified sub-structural features in the modulation of PPARγ activity. Molecular dynamics simulations further underscored the stability of the complexes formed by investigated modulators with PPARγ. Overall, the integration of many computational approaches unveiled key structural motifs essential for PPARγ modulatory activity that will shed light on the development of effective modulators in the future.

A novel fatty acid mimetic with pan-PPAR partial agonist activity inhibits diet-induced obesity and metabolic dysfunction-associated steatotic liver disease

OBJECTIVE

The prevalence of metabolic diseases is increasing globally at an alarming rate; thus, it is essential that effective, accessible, low-cost therapeutics are developed. Peroxisome proliferator-activated receptors (PPARs) are transcription factors that tightly regulate glucose homeostasis and lipid metabolism and are important drug targets for the treatment of type 2 diabetes and dyslipidemia. We previously identified LDT409, a fatty acid-like compound derived from cashew nut shell liquid, as a novel pan-active PPARα/γ/δ compound. Herein, we aimed to assess the efficacy of LDT409 in vivo and investigate the molecular mechanisms governing the actions of the fatty acid mimetic LDT409 in diet-induced obese mice.

METHODS

C57Bl/6 mice (6-11-month-old) were fed a chow or high fat diet (HFD) for 4 weeks; mice thereafter received once daily intraperitoneal injections of vehicle, 10 mg/kg Rosiglitazone, 40 mg/kg WY14643, or 40 mg/kg LDT409 for 18 days while continuing the HFD. During treatments, body weight, food intake, glucose and insulin tolerance, energy expenditure, and intestinal lipid absorption were measured. On day 18 of treatment, tissues and plasma were collected for histological, molecular, and biochemical analysis.

RESULTS

We found that treatment with LDT409 was effective at reversing HFD-induced obesity and associated metabolic abnormalities in mice. LDT409 lowered food intake and hyperlipidemia, while improving insulin tolerance. Despite being a substrate of both PPARα and PPARγ, LDT409 was crucial for promoting hepatic fatty acid oxidation and reducing hepatic steatosis in HFD-fed mice. We also highlighted a role for LDT409 in white and brown adipocytes in vitro and in vivo where it decreased fat accumulation, increased lipolysis, induced browning of WAT, and upregulated thermogenic gene Ucp1. Remarkably, LDT409 reversed HFD-induced weight gain back to chow-fed control levels. We determined that the LDT409-induced weight-loss was associated with a combination of increased energy expenditure (detectable before weight loss was apparent), decreased food intake, increased systemic fat utilization, and increased fecal lipid excretion in HFD-fed mice.

CONCLUSIONS

Collectively, LDT409 represents a fatty acid mimetic that generates a uniquely favorable metabolic response for the treatment of multiple abnormalities including obesity, dyslipidemia, metabolic dysfunction-associated steatotic liver disease, and diabetes. LDT409 is derived from a highly abundant natural product-based starting material and its development could be pursued as a therapeutic solution to the global metabolic health crisis.

Non-alcoholic fatty liver disease in type 2 diabetes: Emerging evidence of benefit of peroxisome proliferator-activated receptors agonists and incretin-based therapies

Nonalcoholic fatty liver disease (NAFLD) is a global epidemic, affecting more than half of the people living with type 2 diabetes (T2D). The relationship between NAFLD and T2D is bidirectional and the presence of one perpetuates the other, which significantly increases the hepatic as well as extrahepatic complications. Until recently, there was no approved pharmacological treatment for NAFLD/ nonalcoholic steatohepatitits (NASH). However, there is evidence that drugs used for diabetes may have beneficial effects on NAFLD. Insulin sensitizers acting through peroxisome proliferator-activated receptor (PPAR) modulation act on multiple levels of NAFLD pathogenesis. Pioglitazone (PPARγ agonist) and saroglitazar (PPARα/γ agonist) are particularly beneficial and recommended by several authoritative bodies for treating NAFLD in T2D, although data on biopsy-proven NASH are lacking with the latter. Initial data on elafibanor (PPAR α/δ agonist) and Lanifibranor (pan PPAR agonist) are promising. On the other hand, incretin therapies based on glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RA) and dual- and triple-hormone receptor co-agonists reported impressive weight loss and may have anti-inflammatory and antifibrotic properties. GLP-1 RAs have shown beneficial effects on NAFLD/NASH and more studies on potential direct effects on liver function by dual- and triple-agonists are required. Furthermore, the long-term safety of these therapies in NAFLD needs to be established. Collaborative efforts among healthcare providers such as primary care doctors, hepatologists, and endocrinologists are warranted for selecting patients for the best possible management of NAFLD in T2D.

Identification of PPAR-related differentially expressed genes liver hepatocellular carcinoma and construction of a prognostic model based on data analysis and molecular docking

Liver hepatocellular carcinoma (LIHC) is a significant global health issue with limited treatment options. In this study, single-cell RNA sequencing (scRNA-seq) data were used to explore the molecular mechanisms of LIHC development and identify potential targets for therapy. The expression of peroxisome proliferator-activated receptors (PPAR)-related genes was analysed in LIHC samples, and primary cell populations, including natural killer cells, T cells, B cells, myeloid cells, endothelial cells, fibroblasts and hepatocytes, were identified. Analysis of the differentially expressed genes (DEGs) between normal and tumour tissues revealed significant changes in gene expression in various cell populations. PPAR activity was evaluated using the 'AUCell' R software, which indicated higher scores in the normal versus the malignant hepatocytes. Furthermore, the DEGs showed significant enrichment of pathways related to lipid and glucose metabolism, cell development, differentiation and inflammation. A prognostic model was then constructed using 8 PPARs-related genes, including FABP5, LPL, ACAA1, PPARD, FABP4, PLIN1, HMGCS2 and CYP7A1, identified using least absolute shrinkage and selection operator-Cox regression analysis, and validated in the TCGA-LIHC, ICGI-LIRI and GSE14520 datasets. Patients with low-risk scores had better prognosis in all cohorts. Based on the expression of the eight model genes, two clusters of patients were identified by ConsensusCluster analysis. We also predicted small-molecule drugs targeting the model genes, and identified perfluorohexanesulfonic acid, triflumizole and perfluorononanoic acid as potential candidates. Finally, wound healing assay confirmed that PPARD can promote the migration of liver cancer cells. Overall, our study offers novel perspectives on the molecular mechanisms of LIHC and potential areas for therapeutic intervention, which may facilitate the development of more effective treatment regimens.

Rose polyphenols exert antiobesity effect in high-fat-induced obese mice by regulating lipogenic gene expression

Obesity presents a major risk factor in the development of cardiovascular diseases. Recent reports indicate that many kinds of polyphenols have the potential to prevent metabolic diseases. We hypothesized that rose polyphenols (ROSE) have the effect of improvement in lipid metabolism. In this study, we investigated whether rose polyphenols affected lipid metabolism and exerted antiobesity. To clarify the mechanism, C57BL/6J mice were fed a high-fat diet containing 0.25% ROSE for 35 days. Compared with the control group, body weight gain and adipose tissue weight in the 0.25% ROSE group were significantly decreased. Serum cholesterol and hepatic triglyceride concentrations significantly decreased, whereas fecal triglyceride was significantly increased in the 0.25% ROSE group. Liver stearoyl-CoA desaturase 1 (Scd1), 3-hydroxy-3-methylglutaryl-CoA reductase (Hmgcr), and acyl-CoA:cholesterol acyltransferase 1 (Acat1) mRNA as well as protein stearoyl-CoA desaturase 1 concentrations were significantly lower in the 0.25% ROSE group than that in the control group. The mRNA and the protein concentrations of adipose triglyceride lipase, hormone-sensitive lipase, and peroxisomal acylcoenzyme A oxidase 1 in white adipose tissue were significantly higher in the 0.25% ROSE group than that in the control group. The components in rose polyphenols were quantified by liquid chromatography-tandem mass spectrometry, and we consider that ellagic acid plays an important role in an antiobesity effect because the ellagic acid content is the highest among polyphenols in rose polyphenols. In summary, rose polyphenols exhibit antiobesity effects by influencing lipid metabolism-related genes and proteins to promote lipolysis and suppress lipid synthesis.

PPARs at the crossroads of T cell differentiation and type 1 diabetes

T-cell-mediated autoimmune type 1 diabetes (T1D) is characterized by the immune-mediated destruction of pancreatic beta cells (β-cells). The increasing prevalence of T1D poses significant challenges to the healthcare system, particularly in countries with struggling economies. This review paper highlights the multifaceted roles of Peroxisome Proliferator-Activated Receptors (PPARs) in the context of T1D, shedding light on their potential as regulators of immune responses and β-cell biology. Recent research has elucidated the intricate interplay between CD4+ T cell subsets, such as Tregs and Th17, in developing autoimmune diseases like T1D. Th17 cells drive inflammation, while Tregs exert immunosuppressive functions, highlighting the delicate balance crucial for immune homeostasis. Immunotherapy has shown promise in reinstating self-tolerance and restricting the destruction of autoimmune responses, but further investigations are required to refine these therapeutic strategies. Intriguingly, PPARs, initially recognized for their role in lipid metabolism, have emerged as potent modulators of inflammation in autoimmune diseases, particularly in T1D. Although evidence suggests that PPARs affect the β-cell function, their influence on T-cell responses and their potential impact on T1D remains largely unexplored. It was noted that PPARα is involved in restricting the transcription of IL17A and enhancing the expression of Foxp3 by minimizing its proteasomal degradation. Thus, antagonizing PPARs may exert beneficial effects in regulating the differentiation of CD4+ T cells and preventing T1D. Therefore, this review advocates for comprehensive investigations to delineate the precise roles of PPARs in T1D pathogenesis, offering innovative therapeutic avenues that target both the immune system and pancreatic function. This review paper seeks to bridge the knowledge gap between PPARs, immune responses, and T1D, providing insights that may revolutionize the treatment landscape for this autoimmune disorder. Moreover, further studies involving PPAR agonists in non-obese diabetic (NOD) mice hold promise for developing novel T1D therapies.

Discovering Venom-Derived Drug Candidates Using Differential Gene Expression

Venoms are a diverse and complex group of natural toxins that have been adapted to treat many types of human disease, but rigorous computational approaches for discovering new therapeutic activities are scarce. We have designed and validated a new platform-named VenomSeq-to systematically identify putative associations between venoms and drugs/diseases via high-throughput transcriptomics and perturbational differential gene expression analysis. In this study, we describe the architecture of VenomSeq and its evaluation using the crude venoms from 25 diverse animal species and 9 purified teretoxin peptides. By integrating comparisons to public repositories of differential expression, associations between regulatory networks and disease, and existing knowledge of venom activity, we provide a number of new therapeutic hypotheses linking venoms to human diseases supported by multiple layers of preliminary evidence.

Tuberculosis alters immune-metabolic pathways resulting in perturbed IL-1 responses

Tuberculosis (TB) remains a major public health problem and we lack a comprehensive understanding of how Mycobacterium tuberculosis (M. tb) infection impacts host immune responses. We compared the induced immune response to TB antigen, BCG and IL-1β stimulation between latently M. tb infected individuals (LTBI) and active TB patients. This revealed distinct responses between TB/LTBI at transcriptomic, proteomic and metabolomic levels. At baseline, we identified a novel immune-metabolic association between pregnane steroids, the PPARγ pathway and elevated plasma IL-1ra in TB. We observed dysregulated IL-1 responses after BCG stimulation in TB patients, with elevated IL-1ra responses being explained by upstream TNF differences. Additionally, distinct secretion of IL-1α/IL-1β in LTBI/TB after BCG stimulation was associated with downstream differences in granzyme mediated cleavage. Finally, IL-1β driven signalling was dramatically perturbed in TB disease but was completely restored after successful treatment. This study improves our knowledge of how immune responses are altered during TB disease, and may support the design of improved preventive and therapeutic tools, including host-directed strategies.

Macrophages, Chronic Inflammation, and Insulin Resistance

The prevalence of obesity has reached alarming levels, which is considered a major risk factor for several metabolic diseases, including type 2 diabetes (T2D), non-alcoholic fatty liver, atherosclerosis, and ischemic cardiovascular disease. Obesity-induced chronic, low-grade inflammation may lead to insulin resistance, and it is well-recognized that macrophages play a major role in such inflammation. In the current review, the molecular mechanisms underlying macrophages, low-grade tissue inflammation, insulin resistance, and T2D are described. Also, the role of macrophages in obesity-induced insulin resistance is presented, and therapeutic drugs and recent advances targeting macrophages for the treatment of T2D are introduced.

PPARδ Agonist Promotes Type II Cartilage Formation in a Rabbit Osteochondral Defect Model

Osteoarthritis (OA) is a chronic degenerative joint disease accompanied by an inflammatory milieu that results in painful joints. The pathogenesis of OA is multifactorial, with genetic predisposition, environmental factors, and traumatic injury resulting in the direct or indirect loss of cartilage. The articular cartilage can also be damaged by direct focal traumatic injury. Articular cartilage provides a smooth, deformable bearing surface with a low coefficient of friction, increased contact area, and reduced contact stress. Articular type II hyaline cartilage lines the synovial joints and, when injured, has a limited ability for repair, except for the most superficial layers via diffusion from the synovial fluid, secondary to no blood supply, a complex structure, and a low metabolic rate. Restoring the articular surface can relieve pain and restore function. Although many strategies have been developed to regenerate type II collagen based on the extent of the lesion, surgical treatments are still evolving. The peroxisome proliferator-activated receptor delta (PPARδ) agonist and collagen treatment of mesenchymal stem cells (MSCs) enhance the chondrogenic capacity in vitro. We present a novel technique for cartilage restoration in a rabbit cartilage osteochondral defect model using a PPARδ agonist (GW0742)-infused 3D collagen scaffold to induce type II cartilage from MSCs.

Single cell atlas identifies lipid-processing and immunomodulatory endothelial cells in healthy and malignant breast

Since a detailed inventory of endothelial cell (EC) heterogeneity in breast cancer (BC) is lacking, here we perform single cell RNA-sequencing of 26,515 cells (including 8433 ECs) from 9 BC patients and compare them to published EC taxonomies from lung tumors. Angiogenic ECs are phenotypically similar, while other EC subtypes are different. Predictive interactome analysis reveals known but also previously unreported receptor-ligand interactions between ECs and immune cells, suggesting an involvement of breast EC subtypes in immune responses. We also identify a capillary EC subtype (LIPEC (Lipid Processing EC)), which expresses genes involved in lipid processing that are regulated by PPAR-γ and is more abundant in peri-tumoral breast tissue. Retrospective analysis of 4648 BC patients reveals that treatment with metformin (an indirect PPAR-γ signaling activator) provides long-lasting clinical benefit and is positively associated with LIPEC abundance. Our findings warrant further exploration of this LIPEC/PPAR-γ link for BC treatment.

Tumor blood vessels contribute to cancer growth, invasion and metastasis. Here, by using single cell transcriptomics, the authors report an inventory of endothelial cell heterogeneity in patients with breast cancer, including a subtype that expresses genes involved in lipid processing and is regulated by PPAR-γ.

Management of Diabetes in Candidates for Liver Transplantation and in Transplant Recipients

Diabetes is common in patients waitlisted for liver transplantation because of end-stage liver disease or hepatocellular cancer as well as in posttransplant phase (posttransplantation diabetes mellitus). In both conditions, the presence of diabetes severely affects disease burden and long-term clinical outcomes; careful monitoring and appropriate treatment are pivotal to reduce cardiovascular events and graft and recipients' death. We thoroughly reviewed the epidemiology of diabetes in the transplant setting and the different therapeutic options, from lifestyle intervention to antidiabetic drug use-including the most recent drug classes available-and to the inclusion of bariatric surgery in the treatment cascade. In waitlisted patients, the old paradigm that insulin should be the treatment of choice in the presence of severe liver dysfunction is no longer valid; novel antidiabetic agents may provide adequate glucose control without the risk of hypoglycemia, also offering cardiovascular protection. The same evidence applies to the posttransplant phase, where oral or injectable noninsulin agents should be considered to treat patients to target, limiting the impact of disease on daily living, without interaction with immunosuppressive regimens. The increasing prevalence of liver disease of metabolic origin (nonalcoholic fatty liver) among liver transplant candidates, also having a higher risk of noncirrhotic hepatocellular cancer, is likely to accelerate the acceptance of new drugs and invasive procedures, as suggested by international guidelines. Intensive lifestyle intervention programs remain however mandatory, both before and after transplantation. Achievement of adequate control is mandatory to increase candidacy, to prevent delisting, and to improve long-term outcomes.

Alpinetin: A Review of Its Pharmacology and Pharmacokinetics

Flavonoids isolated from medicinal herbs have been utilized as valuable health-care agents due to their virous biological applications. Alpinetin is a natural flavonoid that emerges in many widely used medicinal plants, and has been frequently applied in Chinese patent drugs. Accumulated evidence has demonstrated that alpinetin possesses a broad range of pharmacological activities such as antitumor, antiinflammation, hepatoprotective, cardiovascular protective, lung protective, antibacterial, antiviral, neuroprotective, and other properties through regulating multiple signaling pathways with low systemic toxicity. However, pharmacokinetic studies have documented that alpinetin may have poor oral bioavailability correlated to its extensive glucuronidation. Currently, the reported pharmacological properties and pharmacokinetics profiles of alpinetin are rare to be scientifically reviewed. In this article, we aimed to highlight the mechanisms of action of alpinetin in various diseases to strongly support its curative potentials for prospective clinical applications. We also summarized the pharmacokinetics properties and proposed some viable strategies to convey an appreciable reference for future advances of alpinetin in drug development.

Coordinated regulation of gene expression and microRNA changes in adipose tissue and circulating extracellular vesicles in response to pioglitazone treatment in humans with type 2 diabetes

Pioglitazone, a PPARγ agonist, is used to treat type 2 diabetes (T2D). PPARγ is highly expressed in adipose tissue (AT), however the effects of pioglitazone to improve insulin sensitivity are also evident in other tissues and PPARγ agonism has been shown to alter cancer derived extracellular vesicle (EV)-miRNAs. We hypothesized that pioglitazone modifies the cargo of circulating AT-derived EVs to alter interorgan crosstalk in people with diabetes. We tested our hypothesis in a 3-month trial in which 24 subjects with T2D were randomized to treatment with either pioglitazone 45 mg/day or placebo (NCT00656864). Levels of 42 adipocyte-derived EV-miRNAs were measured in plasma EVs using low density TaqMan arrays. Levels of differentially expressed EV-miRNAs and their most relevant target genes were also measure in adipose tissue from the same participants, using individual TaqMan assays. Levels of 5 miRNAs (i.e., miR-7-5p, miR-20a-5p, miR-92a-3p, miR-195-5p, and miR-374b-5p) were significantly downregulated in EVs in response to pioglitazone treatment relative to placebo. The opposite occurred for miR-195-5p in subcutaneous AT. Changes in miRNA expression in EVs and AT correlated with changes in suppression of lipolysis and improved insulin sensitivity, among others. DICER was downregulated and exosomal miRNA sorting-related genes YBX1 and hnRNPA2B1 displayed a downregulation trend in AT. Furthermore, analysis of EV-miRNA targeted genes identified a network of transcripts that changed in a coordinated manner in AT. Collectively, our results suggest that some beneficial pharmacologic effects of pioglitazone are mediated by adipose-specific miRNA regulation and exosomal/EV trafficking.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, identifier NCT00656864.

The pleiotropic peroxisome proliferator activated receptors: Regulation and therapeutics

The Peroxisome proliferator-activated receptors (PPARs) are key regulators of metabolic events in our body. Owing to their implication in maintenance of homeostasis, both PPAR agonists and antagonists assume therapeutic significance. Understanding the molecular mechanisms of each of the PPAR isotypes in the healthy body and during disease is crucial to exploiting their full therapeutic potential. This article is an attempt to present a rational analysis of the multifaceted therapeutic effects and underlying mechanisms of isotype-specific PPAR agonists, dual PPAR agonists, pan PPAR agonists as well as PPAR antagonists. A holistic understanding of the mechanistic dimensions of these key metabolic regulators will guide future efforts to identify novel molecules in the realm of metabolic, inflammatory and immunotherapeutic diseases.

Elucidating the Neuroprotective Role of PPARs in Parkinson's Disease: A Neoteric and Prospective Target

One of the utmost frequently emerging neurodegenerative diseases, Parkinson's disease (PD) must be comprehended through the forfeit of dopamine (DA)-generating nerve cells in the substantia nigra pars compacta (SN-PC). The etiology and pathogenesis underlying the emergence of PD is still obscure. However, expanding corroboration encourages the involvement of genetic and environmental factors in the etiology of PD. The destruction of numerous cellular components, namely oxidative stress, ubiquitin-proteasome system (UPS) dysfunction, autophagy-lysosome system dysfunction, neuroinflammation and programmed cell death, and mitochondrial dysfunction partake in the pathogenesis of PD. Present-day pharmacotherapy can alleviate the manifestations, but no therapy has been demonstrated to cease disease progression. Peroxisome proliferator-activated receptors (PPARs) are ligand-directed transcription factors pertaining to the class of nuclear hormone receptors (NHR), and are implicated in the modulation of mitochondrial operation, inflammation, wound healing, redox equilibrium, and metabolism of blood sugar and lipids. Numerous PPAR agonists have been recognized to safeguard nerve cells from oxidative destruction, inflammation, and programmed cell death in PD and other neurodegenerative diseases. Additionally, various investigations suggest that regular administration of PPAR-activating non-steroidal anti-inflammatory drugs (NSAIDs) (ibuprofen, indomethacin), and leukotriene receptor antagonists (montelukast) were related to the de-escalated evolution of neurodegenerative diseases. The present review elucidates the emerging evidence enlightening the neuroprotective outcomes of PPAR agonists in in vivo and in vitro models experiencing PD. Existing articles up to the present were procured through PubMed, MEDLINE, etc., utilizing specific keywords spotlighted in this review. Furthermore, the authors aim to provide insight into the neuroprotective actions of PPAR agonists by outlining the pharmacological mechanism. As a conclusion, PPAR agonists exhibit neuroprotection through modulating the expression of a group of genes implicated in cellular survival pathways, and may be a propitious target in the therapy of incapacitating neurodegenerative diseases like PD.

Syringaldehyde promoting intestinal motility with suppressing α-amylase hinders starch digestion in diabetic mice

The antihyperglycemic potential of syringaldehyde has been previously investigated; however, the underlying mechanism remains unclear. In this study, we performed a postprandial glucose test (in vivo) including oral glucose tolerance test (OGTT) and oral starch tolerance test (OSTT) in fructose-induced diabetic mice on a high-fat diet for mimicking type 2 diabetes to explore the hypoglycemic efficacy of syringaldehyde and the underlined molecular involvement of syringaldehyde in a glucose-lowering effect. The results revealed that syringaldehyde dose-dependently suppressed blood glucose in both the OSTT and OGTT when referenced to acarbose and metformin, respectively. Surprisingly, syringaldehyde triggered jejunum motility (ex vivo) via activation of the muscarinic-type acetylcholine receptor. By performing virtual screening with molecular docking, the data showed that syringaldehyde nicely interacted with glucagon-like peptide 1 receptor (GLP-1R), peroxisome proliferator-activated receptor (PPAR), dipeptidyl peptidase-IV (DPP-4), acetylcholine M2 receptor, and acetylcholinesterase. These results showed that syringaldehyde can potentiate intestinal contractility to abolish the α-amylase reaction when concurrently reducing retention time and glucose absorption to achieve a glucose-lowering effect in diabetic mice, suggesting its potential therapeutic benefits with improvement for use as a prophylactic and treatment.

Role of Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) in Different Disease States: Recent Updates

Peroxisome proliferator-activated receptor (PPAR), a ligand dependant transcription factor, is a member of the nuclear receptor superfamily. PPAR exists in three isoforms i.e. PPAR alpha (PPARα), PPAR beta (PPARβ), and PPAR gamma (PPARγ). These are multi-functional transcription factors and help in regulating inflammation, type 2 diabetes, lipid concentration in the body, metastasis, and tumor growth or angiogenesis. Activation of PPARγ causes inhibition of growth of cultured human breast, gastric, lung, prostate, and other cancer cells. PPARγ is mainly involved in fatty acid storage, glucose metabolism, and homeostasis and adipogenesis regulation. A large number of natural and synthetic ligands bind to PPARγ and modulate its activity. Ligands such as thiazolidinedione, troglitazone, rosiglitazone, pioglitazone effectively bind to PPARγ; however, most of these were found to display severe side effects such as hepatotoxicity, weight gain, cardiovascular complications and bladder tumor. Now the focus is shifted towards the development of dual-acting or pan PPAR ligands. The current review article describes the functions and role of PPARγ in various disease states. In addition, recently reported PPARγ ligands and pan PPAR ligands were discussed in detail. It is envisaged that the present review article may help in the development of potent PPAR ligands with no or minimal side effects.

α-Amyrin induces GLUT4 translocation mediated by AMPK and PPARδ/γ in C2C12 myoblasts

α-Amyrin, a natural pentacyclic triterpene, has an antihyperglycemic effect in mice and dual PPARδ/γ action in 3T3-L1 adipocytes, and potential in the control of type 2 diabetes (T2D). About 80% of glucose uptake occurs in skeletal muscle cells, playing a significant role in insulin resistance (IR) and T2D. Peroxisome-proliferator activated receptors (PPARs), in particular PPARδ and PPARγ, are involved in the regulation of lipids and carbohydrates and, along with adenosine-monophosphate (AMP) - activated protein kinase (AMPK) and protein kinase B (Akt), are implicated in translocation of glucose transporter 4 (GLUT4); however, it is still unknown whether α-amyrin can affect these pathways in skeletal muscle cells. Our objective was to determine the action of α-amyrin in PPARδ, PPARγ, AMPK, and Akt in C2C12 myoblasts. The expression of PPARδ, PPARγ, fatty acid transporter protein (FATP), and GLUT4 was quantified using reverse transcription quantitative PCR and Western blot. α-Amyrin increased these markers along with phospho-AMPK (p-AMPK) but not p-Akt. Molecular docking showed that α-amyrin acts as an AMPK-allosteric activator, and may be related to GLUT4 translocation, as evidenced by confocal microscopy. These data support that α-amyrin could have an insulin-mimetic action in C2C12 myoblasts and should be considered as a bioactive molecule for new multitarget drugs with utility in T2D and other metabolic diseases.

Network pharmacology of bioactives from Sorghum bicolor with targets related to diabetes mellitus

BACKGROUND

Sorghum bicolor (SB) is rich in protective phytoconstituents with health benefits and regarded as a promising source of natural anti-diabetic substance. However, its comprehensive bioactive compound(s) and mechanism(s) against type-2 diabetes mellitus (T2DM) have not been exposed. Hence, we implemented network pharmacology to identify its key compounds and mechanism(s) against T2DM.

METHODS

Compounds in SB were explored through GC-MS and screened by Lipinski's rule. Genes associated with the selected compounds or T2DM were extracted from public databases, and the overlapping genes between SB-compound related genes and T2DM target genes were identified using Venn diagram. Then, the networking between selected compounds and overlapping genes was constructed, visualized, and analyzed by RStudio. Finally, affinity between compounds and genes was evaluated via molecular docking.

RESULTS

GC-MS analysis of SB detected a total of 20 compounds which were accepted by the Lipinski's rule. A total number of 16 compounds-related genes and T2DM-related genes (4,763) were identified, and 81 overlapping genes between them were selected. Gene set enrichment analysis exhibited that the mechanisms of SB against T2DM were associated with 12 signaling pathways, and the key mechanism might be to control blood glucose level by activating PPAR signaling pathway. Furthermore, the highest affinities were noted between four main compounds and six genes (FABP3-Propyleneglyco monoleate, FABP4-25-Oxo-27-norcholesterol, NR1H3-Campesterol, PPARA-β-sitosterol, PPARD-β-sitosterol, and PPARG-β-sitosterol).

CONCLUSION

Our study overall suggests that the four key compounds detected in SB might ameliorate T2DM severity by activating the PPAR signaling pathway.

Synthesis and evaluation of novel peptidomimetics bearing p-aminobenzoic acid moiety as potential antidiabetic agents

Aim: Search for a new class of potential antidiabetic agents. Methodology: A series of novel peptidomimetics bearing the p-aminobenzoic acid moiety (TM3-TM6) were designed and synthesized. For all synthetic target molecules, the peroxisome proliferator response element (PPRE) activated activities have been evaluated and the toxicity were computed. Results & discussion: 46 new p-aminobenzoic acid derivatives have been characterized by ¹H NMR, ¹³C NMR and high-resolution mass spectrometry (HRMS). The results of in vitro PPRE-activated activity, molecular docking study and toxicity prediction revealed that these compounds had potential antidiabetic activities and low toxicity. In particular compound 3b had up to 87% PPRE-activated activity compared with pioglitazone. This discovery may provide new insights for finding novel PPRE lead compound.

Heart Failure in Type 2 Diabetes Mellitus

Patients with diabetes mellitus have >2× the risk for developing heart failure (HF; HF with reduced ejection fraction and HF with preserved ejection fraction). Cardiovascular outcomes, hospitalization, and prognosis are worse for patients with diabetes mellitus relative to those without. Beyond the structural and functional changes that characterize diabetic cardiomyopathy, a complex underlying, and interrelated pathophysiology exists. Despite the success of many commonly used antihyperglycemic therapies to lower hyperglycemia in type 2 diabetes mellitus the high prevalence of HF persists. This, therefore, raises the possibility that additional factors beyond glycemia might contribute to the increased HF risk in diabetes mellitus. This review summarizes the state of knowledge about the impact of existing antihyperglycemic therapies on HF and discusses potential mechanisms for beneficial or deleterious effects. Second, we review currently approved pharmacological therapies for HF and review evidence that addresses their efficacy in the context of diabetes mellitus. Dysregulation of many cellular mechanisms in multiple models of diabetic cardiomyopathy and in human hearts have been described. These include oxidative stress, inflammation, endoplasmic reticulum stress, aberrant insulin signaling, accumulation of advanced glycated end-products, altered autophagy, changes in myocardial substrate metabolism and mitochondrial bioenergetics, lipotoxicity, and altered signal transduction such as GRK (g-protein receptor kinase) signaling, renin angiotensin aldosterone signaling and β-2 adrenergic receptor signaling. These pathophysiological pathways might be amenable to pharmacological therapy to reduce the risk of HF in the context of type 2 diabetes mellitus. Successful targeting of these pathways could alter the prognosis and risk of HF beyond what is currently achieved using existing antihyperglycemic and HF therapeutics.

A New Perspective in Utilizing MMP-9 as a Therapeutic Target for Alzheimer's Disease and Type 2 Diabetes Mellitus

Matrix metalloprotease 9 (MMP-9) is a 92 kDa type IV collagenase and a member of the family of endopeptidases. MMP-9 is involved in the degradation of extracellular matrix components, tissue remodeling, cellular receptor stripping, and processing of various signaling molecules. In the CNS, the effects of MMP-9 are quite complex, since it exerts beneficial effects including neurogenesis, angiogenesis, myelogenesis, axonal growth, and inhibition of apoptosis, or destructive effects including apoptosis, blood-brain barrier disorder, and demyelination. Likewise, in the periphery, physiological events, as the involvement of MMP-9 in angiogenesis, for instance in wound healing, can be turned into pathological, such as in tumor metastasis, depending on the state of the organism. Alzheimer's disease is a neurodegenerative disorder, characterized by amyloid accumulation and deposition in the brain. Amyloidogenesis, however, also occurs in diseases of the periphery, such as type II diabetes mellitus, where an analogous type of amyloid, is deposited in the pancreas. Interestingly, both diseases exhibit similar pathology and disease progression, with insulin resistance being a major common denominator. Hence, combinatorial strategies searching new or existing molecules to apply for therapeutic use for both diseases are gaining momentum. MMP-9 is extensively studied due to its association with a variety of physiological and pathological processes. Consequently, meticulous design could render MMP-9 into a potential therapeutic target for Alzheimer's disease and type 2 diabetes mellitus; two seemingly unrelated diseases.

The Antagonist Effect of Arachidonic Acid on GLUT4 Gene Expression by Nuclear Receptor Type II Regulation

OBJECTIVES

Obesity is a complex disease that has a strong association with diet and lifestyle. Dietary factors can influence the expression of key genes connected to insulin resistance, lipid metabolism, and adipose tissue composition. In this study, our objective was to determine gene expression and fatty acid (FA) profiles in visceral adipose tissue (VAT) from lean and morbidly obese individuals. We also aimed to study the agonist effect of dietary factors on glucose metabolism.

DESIGN AND METHODS

Lean and low and high insulin resistance morbidly obese subjects (LIR-MO and HIR-MO) were included in this study. The gene expression of liver X receptor type alpha (LXR-α) and glucose transporter type 4 (GLUT4) and the FA profiles in VAT were determined. Additionally, the in vivo and in vitro agonist effects of oleic acid (OA), linoleic acid (LA), and arachidonic acid (AA) by peroxisome proliferator-activated receptor type gamma 2 (PPAR-γ2) on the activity of GLUT4 were studied.

RESULTS

Our results showed a dysregulation of GLUT4 and LXR-α in VAT of morbidly obese subjects. In addition, a specific FA profile for morbidly obese individuals was found. Finally, AA was an PPAR-γ2 agonist that activates the expression of GLUT4.

CONCLUSIONS

Our study suggests a dysregulation of LXR-α and GLUT4 expression in VAT of morbidly obese individuals. FA profiles in VAT could elucidate their possible role in lipolysis and adipogenesis. Finally, AA binds to PPAR-γ2 to activate the expression of GLUT4 in the HepG2 cell line, showing an alternative insulin-independent activation of GLUT4.

Peroxisome Proliferator-Activated Receptors and Their Agonists in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases worldwide. In addition to the liver-related morbidity and mortality, NAFLD is now also associated with various extrahepatic diseases. Pathogenesis of NAFLD is multifactorial with limited pharmacotherapy options for the treatment of patients with NAFLD. Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that are involved in the transcriptional regulation of lipid metabolism, glucose homeostasis, energy balance, inflammation, and atherosclerosis. PPAR agonists are attractive options for treatment of NAFLD as they can act at multiple targets involved in the pathogenesis of NAFLD. We reviewed the available literature on the pathophysiological role of PPARs and use of PPAR agonists in the treatment of NAFLD. Original studies and review articles available on PubMed regarding the role of PPARs in the pathogenesis and utility of PPAR agonists in the treatment of NAFLD were included in this review article. ClinicalTrials.gov and Clinical Trials Registry-India sites were searched for ongoing studies on saroglitazar. The available literature suggests that PPARs play an important role in the pathogenesis of NAFLD. Use of PPAR gamma agonists is associated with histological improvement in NAFLD. Dual PPAR agonists with no or minimal PPAR gamma activity are being explored in the treatment of NAFLD. Because of the pathophysiological role of PPARs in NAFLD, PPAR agonists are attractive options for the treatment of patients with NAFLD. Dual PPAR agonists without significant gamma activity appear promising for the treatment of NAFLD.

Structure-guided evolution of a 2-phenyl-4-carboxyquinoline chemotype into PPARα selective agonists: New leads for oculovascular conditions

Small molecule agonism of PPARα represents a promising new avenue for the development of non-invasive treatments for oculovascular diseases like diabetic retinopathy and age-related macular degeneration. Herein we report initial structure-activity relationships for the newly identified quinoline-based PPARα agonist, Y-0452. Preliminary computational studies led to the hypothesis that carboxylic acid transposition and deconstruction of the Y-0452 quinoline system would enhance ligand-protein interactions and better complement the nature of the binding pocket. A focused subset of analogs was designed, synthesized, and assessed for PPARα agonism. Two key observations arose from this work 1) contrary to other PPARα agonists, incorporation of the fibrate "head-group" decreases PPARα selectivity and instead provides pan-PPAR agonists and 2) computational models reveal a relatively unexploited amphiphilic pocket in PPARα that provides new opportunities for the development of novel agonists. As an example, compound 10 exhibits more potent PPARα agonism (EC50 = ∼6 µM) than Y-0452 (EC50 = ∼50 µM) and manifests >20-fold selectivity for PPARα over the PPARγ and PPARδ isoforms. More detailed biochemical analysis of 10 confirms typical downstream responses of PPARα agonism including PPARα upregulation, induction of target genes, and inhibition of cell migration.

Role of peroxisome proliferator-activated receptors in non-alcoholic fatty liver disease inflammation

Overweight and obesity have been identified as the most important risk factors for many diseases, including cardiovascular disease, type 2 diabetes and lipid disorders, such as non-alcoholic fatty liver disease (NAFLD). The metabolic changes associated with obesity are grouped to define metabolic syndrome, which is one of the main causes of morbidity and mortality in industrialized countries. NAFLD is considered to be the hepatic manifestation of metabolic syndrome and is one of the most prevalent liver diseases worldwide. Inflammation plays an important role in the development of numerous liver diseases, contributing to the progression to more severe stages, such as non-alcoholic steatohepatitis and hepatocellular carcinoma. Peroxisome proliferator-activated receptors (PPARs) are binder-activated nuclear receptors that are involved in the transcriptional regulation of lipid metabolism, energy balance, inflammation and atherosclerosis. Three isotypes are known: PPAR-α, PPARδ/β and PPAR-γ. These isotypes play different roles in diverse tissues and cells, including the inflammatory process. In this review, we discuss current knowledge on the role PPARs in the hepatic inflammatory process involved in NAFLD as well as new pharmacological strategies that target PPARs.

Enhancer-driven transcriptional regulation is a potential key determinant for human visceral and subcutaneous adipocytes

Obesity is characterized by the excess of body fat leading to impaired health. Abdominal fat is particularly harmful and is associated with cardiovascular and metabolic diseases and cancer. In contrast, subcutaneous fat is generally considered less detrimental. The mechanisms that establish the cellular characteristics of these distinct fat types in humans are not fully understood. Here, we explored whether differences of their gene regulatory mechanisms can be investigated in vitro. For this purpose, we in vitro differentiated human visceral and subcutaneous pre-adipocytes into mature adipocytes and obtained their gene expression profiles and genome-wide H3K4me3, H3K9me3 and H3K27ac patterns. Subsequently, we compared those data with public gene expression data from visceral and subcutaneous fat tissues. We found that the in vitro differentiated adipocytes show significant differences in their transcriptional landscapes, which correlate with biological pathways that are characteristic for visceral and subcutaneous fat tissues, respectively. Unexpectedly, visceral adipocyte enhancers are rich on motifs for transcription factors involved in the Hippo-YAP pathway, cell growth and inflammation, which are not typically associated with adipocyte function. In contrast, enhancers of subcutaneous adipocytes show enrichment of motifs for common adipogenic transcription factors, such as C/EBP, NFI and PPARγ, implicating substantially disparate gene regulatory networks in visceral and subcutaneous adipocytes. Consistent with the role in obesity, predominantly the histone modification pattern of visceral adipocytes is linked to obesity-associated diseases. Thus, this work suggests that the properties of visceral and subcutaneous fat tissues can be studied in vitro and provides preliminary insights into their gene regulatory processes.

The Effects of PPAR Stimulation on Cardiac Metabolic Pathways in Barth Syndrome Mice

Aim: Tafazzin knockdown (TazKD) in mice is widely used to create an experimental model of Barth syndrome (BTHS) that exhibits dilated cardiomyopathy and impaired exercise capacity. Peroxisome proliferator-activated receptors (PPARs) are a group of nuclear receptor proteins that play essential roles as transcription factors in the regulation of carbohydrate, lipid, and protein metabolism. We hypothesized that the activation of PPAR signaling with PPAR agonist bezafibrate (BF) may ameliorate impaired cardiac and skeletal muscle function in TazKD mice. This study examined the effects of BF on cardiac function, exercise capacity, and metabolic status in the heart of TazKD mice. Additionally, we elucidated the impact of PPAR activation on molecular pathways in TazKD hearts.

Methods: BF (0.05% w/w) was given to TazKD mice with rodent chow. Cardiac function in wild type-, TazKD-, and BF-treated TazKD mice was evaluated by echocardiography. Exercise capacity was evaluated by exercising mice on the treadmill until exhaustion. The impact of BF on metabolic pathways was evaluated by analyzing the total transcriptome of the heart by RNA sequencing.

Results: The uptake of BF during a 4-month period at a clinically relevant dose effectively protected the cardiac left ventricular systolic function in TazKD mice. BF alone did not improve the exercise capacity however, in combination with everyday voluntary running on the running wheel BF significantly ameliorated the impaired exercise capacity in TazKD mice. Analysis of cardiac transcriptome revealed that BF upregulated PPAR downstream target genes involved in a wide spectrum of metabolic (energy and protein) pathways as well as chromatin modification and RNA processing. In addition, the Ostn gene, which encodes the metabolic hormone musclin, is highly induced in TazKD myocardium and human failing hearts, likely as a compensatory response to diminished bioenergetic homeostasis in cardiomyocytes.

Conclusion: The PPAR agonist BF at a clinically relevant dose has the therapeutic potential to attenuate cardiac dysfunction, and possibly exercise intolerance in BTHS. The role of musclin in the failing heart should be further investigated.

Peroxisome proliferator-activated receptors as therapeutic targets for heart failure

Heart failure (HF) is a common clinical syndrome that affects more than 23 million individuals worldwide. Despite the marked advances in its management, the mortality rates in HF patients have remained unacceptably high. Peroxisome proliferator-activated receptors (PPARs) are nuclear transcription regulators, involved in the regulation of fatty acid and glucose metabolism. PPAR agonists are currently used for the treatment of type II diabetes mellitus and hyperlipidemia; however, their role as therapeutic agents for HF remains under investigation. Preclinical studies have shown that pharmacological modulation of PPARs can upregulate the expression of fatty acid oxidation genes in cardiomyocytes. Moreover, PPAR agonists were proven able to improve ventricular contractility and reduce cardiac remodelling in animal models through their anti-inflammatory, anti-oxidant, anti-fibrotic, and anti-apoptotic activities. Whether these effects can be replicated in humans is yet to be proven. This article reviews the interactions of PPARs with the pathophysiological mechanisms of HF and how the pharmacological modulation of these receptors can be of benefit for HF patients.

Potential of the chlorogenic acid as multitarget agent: Insulin-secretagogue and PPAR α/γ dual agonist

The chlorogenic acid (CGA) is a natural product isolated from Cecropia obtusifolia, which possesses several pharmacological properties, such as: anti-carcinogenic, neuroprotective, antioxidant, anti-inflammatory, hypoglycemic, and hypolipidemic. In relation to its effects on the hyperglycemia and hypertriglyceridemia, few is known about the mechanisms in which this compound may be acting, therefore, the aim of the present study was to determine if CGA acts as an insulin secretagogue increasing intracellular calcium concentrations ([Ca²⁺]_i) in RINm5F cells; or as an insulin sensitizer and lipid-lowering agent stimulating the expression of PPARγ and PPARα, respectively, in 3T3-L1 adipocytes. As results, RINm5F cells treated with 200μM of CGA showed an increase in [Ca²⁺]_i of 9-times versus control and 4-times as compared to positive control; in addition, an increase in insulin secretion was observed similarly to those of positive control. CGA also significantly increased the mRNA expression of PPARγ (150%) and GLUT4 (220%), as well PPARα (40%) and FATP (25%) as it was appreciated by RT-PCR. Additionally, a chemoinformatic analysis suggested that CGA has suitable physicochemical properties to be considered as leader bioactive molecule for the development of novel agents with similar properties. Together, our results indicate that CGA possesses multiple mechanisms of action for the development of highly effective therapeutics in the treatment of metabolic diseases such as type 2 diabetes.

The Role of Peroxisome Proliferator-Activated Receptor γ in Mediating Cardioprotection Against Ischemia/Reperfusion Injury

Myocardial infarction (MI) is a serious cardiovascular disease resulting in high rates of morbidity and mortality. Although advances have been made in restoring myocardial perfusion in ischemic areas, decreases in cardiomyocyte death and infarct size are still limited, attributing to myocardial ischemia/reperfusion (I/R) injury. It is necessary to develop therapies to restrict myocardial I/R injury and protect cardiomyocytes against further damage after MI. Many studies have suggested that peroxisome proliferator-activated receptor γ (PPARγ), a ligand-inducible nuclear receptor that predominantly regulates glucose and lipid metabolism, is a promising therapeutic target for ameliorating myocardial I/R injury. Thus, this review focuses on the role of PPARγ in cardioprotection during myocardial I/R. The cardioprotective effects of PPARγ, including attenuating oxidative stress, inhibiting inflammatory responses, improving glucose and lipid metabolism, and antagonizing apoptosis, are described. Additionally, the underlying mechanisms of cardioprotective effects of PPARγ, such as regulating the expression of target genes, influencing other transcription factors, and modulating kinase signaling pathways, are further discussed.

Therapeutic molecules against type 2 diabetes: What we have and what are we expecting?

World Health Organization (WHO) has identified diabetes as one of the fastest growing non-communicable diseases with 422 million patients around the world in 2014. Diabetes, a metabolic disease, is characterized primarily by hyperglycemia which results in various macrovascular and microvascular complications like cardiovascular disease and neuropathies which can significantly deteriorate the quality of life. The body either does not manufactures enough insulin (type 1 diabetes or T1DM) or becomes insensitive to physiologically secreted insulin or both (type 2 diabetes or T2DM). The majority of the diabetic population is affected by type 2 diabetes. Currently, hyperglycemia is treated by a broad range of molecules such as biguanides, sulfonylurea, insulin, thiazolidinediones, incretin mimetics, and DPP-4 inhibitors exerting different mechanisms. However, new drug classes have indeed come in the market such as SGLT-2 inhibitors and other are in the experimental stages such as GPR 40 agonists, GSK-3 inhibitors, GK activators and GPR21 inhibitors which definitely could be anticipated as safe and effective for diabetes therapy. This article reviews the general approach to currently approved therapies for type 2 diabetes and focusing on novel approaches that could be a panacea and might be useful in the future for diabetes patients.

Novel avenues for treating diabetic nephropathy: new investigational drugs

At present, treatment of diabetic kidney disease (DKD) is still mainly based on drugs acting on glycemic and blood pressure control, as there is no validated therapy able to halt the progression of renal failure. Because of the high incidence of DKD, due to the increase of diabetes mellitus in general population, new therapeutic strategies are needed. Areas covered: We analysed ongoing and already completed clinical trials, from clinicaltrials.gov and PubMed, dealing with new therapies for DKD. Expert opinion: Among the drugs currently being explored, the most promising molecules are those that interfere with glucose-dependent pathways, in particular polyol, protein kinase, hexosamine and AGEs metabolic pathways, and impaired renal vascular regulation. One of the recent goals achieved by molecular biology is the development of monoclonal antibodies able to interfere with extracellular matrix accumulation and fibrosis. Other interesting therapies are under investigation and further studies with a greater number of patients will establish a better approach for diabetic nephropathy.

Design, synthesis, molecular modeling and anti-hyperglycemic evaluation of novel quinoxaline derivatives as potential PPARγ and SUR agonists

In our effort to develop potent anti-hyperglycemic agents with potential agonistic activities toward PPARγ and SUR, three novel series of quinoxaline derivatives bearing sulfonylurea or sulfonylthiourea moieties with different linkers were designed and synthesized. Some of the newly synthesized compounds were evaluated in vivo for their anti-hyperglycemic activities in STZ-induced hyperglycemic rats. Compounds 15_a, 15_e, 19_b and 24_a exhibited the highest anti-hyperglycemic activities with % reduction in blood glucose level of (50.58, 43.84, 45.10 and 49.62, respectively). Additionally, eight compounds revealed potent anti-hyperglycemic activities were further evaluated in vitro for their PPARγ binding affinity and insulin-secreting ability as potential mechanisms for anti-hyperglycemic activity. Four compounds (15_a, 15_b, 15_d and 15_e) significantly bound to PPARγ with IC₅₀ values of 0.482, 0.491, 0.350 and 0.369μM, respectively. Moreover, Compounds 15_a and 15_b have demonstrated induction of insulin-secretion with EC₅₀ values of 0.92 and 0.98μM, respectively. Furthermore, molecular docking and pharmacophore generation techniques were carried out to investigate binding patterns and fit values of the designed compounds with PPARγ and SUR, respectively.

MicroRNAs-Dependent Regulation of PPARs in Metabolic Diseases and Cancers

Peroxisome proliferator-activated receptors (PPARs) are a family of ligand-dependent nuclear receptors, which control the transcription of genes involved in energy homeostasis and inflammation and cell proliferation/differentiation. Alterations of PPARs' expression and/or activity are commonly associated with metabolic disorders occurring with obesity, type 2 diabetes, and fatty liver disease, as well as with inflammation and cancer. Emerging evidence now indicates that microRNAs (miRNAs), a family of small noncoding RNAs, which fine-tune gene expression, play a significant role in the pathophysiological mechanisms regulating the expression and activity of PPARs. Herein, the regulation of PPARs by miRNAs is reviewed in the context of metabolic disorders, inflammation, and cancer. The reciprocal control of miRNAs expression by PPARs, as well as the therapeutic potential of modulating PPAR expression/activity by pharmacological compounds targeting miRNA, is also discussed.

Peroxisome proliferator-activated receptor (PPAR) α and δ activators induce ICAM-1 expression in quiescent non stimulated endothelial cells

Background

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that are implicated in the regulation of lipid and glucose homeostasis. PPAR agonists have been shown to control inflammatory processes, in part by inhibiting the expression of distinct proinflammatory genes such as vascular cell adhesion molecule-1 (VCAM-1), IL-8, and intercellular adhesion molecule-1 (ICAM-1). ICAM-1 is an important endothelial membrane receptor that facilitates the transmigration of leukocytes across the endothelium. To date, the influence of PPARα and δ activators on the expression of ICAM-1 in non-induced, quiescent endothelial cells has been unclear. Therefore, we examined the effects of various PPARα and δ agonists on the expression of ICAM-1 in non-stimulated primary human endothelial cells.

Results

We found that PPARα and PPARδ agonists significantly induced ICAM-1 surface, intracellular protein, and mRNA expression in a time and concentration-dependent manner. The PPARδ induced ICAM-1 expression could be paralleled with a significantly increased T-cell adherence to the endothelial cells whereas PPARα failed to do so. Transcriptional activity studies using an ICAM-1 reporter gene constructs revealed that PPARδ, but not PPARα agonists induced gene expression by stimulating ICAM-1 promoter activity via an Sp1 transcription factor binding site and inhibit the binding of the transcription factors Sp1 and Sp3. Furthermore, we performed mRNA stability assays and found that PPARα and PPARδ agonists increased ICAM-1 mRNA stability.

Conclusion

Therefore, our data provide the first evidence that PPARα and PPARδ agonists induce ICAM-1 expression in non-stimulated endothelial cells via transcriptional and posttranscriptional mechanisms.

Combination of Vildagliptin and Pioglitazone in Experimental Type 2 Diabetes in Male Rats

Preclinical Research The majority of studies on vildagliptin and pioglitazone have focused on their combination in glycemic control. The aim of the present study was to investigate their effects in combination on (i) hyperglycemia-induced oxidative stress and inflammation and (ii) on organs involved in the pathophysiology of diabetes, pancreas, kidney and liver. Type 2 diabetes was induced using low-dose streptozotocin in male Wistar rats. Diabetic rats were treated for 4 weeks, with vildagliptin (10 mg/kg/day), pioglitazone (10 mg/kg/day) and their combination. Diabetic rats showed elevated fasting serum glucose, fasting serum insulin, serum transaminases together with a deleterious lipid profile and elevated serum creatinine and urea concentrations. Serum levels of the inflammatory markers tumor necrosis factor-α (TNF-α) and nitrite/nitrate were also elevated compared to normal rats. Oxidative stress was manifested by lowered hepatic reduced glutathione (GSH) and increased malondialdehyde (MDA) levels. Pancreatic sections from diabetic rats showed degenerated islets with poorly maintained architecture that was prevented by drug treatment. Pioglitazone was generally more effective than vildagliptin in the studied parameters except for the lipid profile where the effect of both drugs was comparable and for the liver enzymes and renal parameters where vildagliptin was more effective. The combination of vildagliptin and pioglitazone produced superior effects than either drug alone. Drug Dev Res 77 : 251-257, 2016. © 2016 Wiley Periodicals, Inc.

Peroxisome proliferator-activated receptors in cardiac energy metabolism and cardiovascular disease

Cardiomyocytes mainly depend on energy produced from the oxidation of fatty acids and mitochondrial oxidative phosphorylation. Shortage of energy or excessive fat accumulation can lead to cardiac disorders. High saturated fat intake and a sedentary life style have a major influence in the development of cardiovascular disease (CVD). Peroxisome proliferator-activated receptors (PPARs), one of the nuclear receptor super family members, play critical role in the metabolism of lipids by regulating their oxidation and storage. Furthermore, they are involved in glucose homeostasis as well. PPARs, mainly alpha (α) and beta/delta (β/δ), have a significant effect on the lipid metabolism and anti-inflammation in endothelial cells (ECs), vascular smooth muscle cells, and also in cardiomyocytes. Pro-inflammatory cytokines, mainly tumour necrosis factor-α, released at the site of inflammation in the sub-ECs of coronary arteries can inactivate the PPARs which can eventually lead to decreased energy production in the myocardium. Various synthetic ligands of PPAR-α and β/δ have many favourable effects in modulating the vascular diseases and heart failure. Despite the adverse effects from therapy using PPAR- gamma ligands, several laboratories are now focused on synthesizing partial activators which may combine their beneficial effects with lowering of undesirable side effects. This review discusses the role of isoforms of PPAR in the cardiomyocytes energy balance and CVD. The knowledge will help in the synthesis of ligands for their partial activation in order to render energy balance and protection from CVD.

Comparative risk of severe hypoglycemia among concomitant users of thiazolidinedione antidiabetic agents and antihyperlipidemics

We conducted high-dimensional propensity score-adjusted cohort studies to examine whether thiazolidinedione use with a statin or fibrate was associated with an increased risk of severe hypoglycemia. We found that concomitant therapy with a thiazolidinedione+fibrate was associated with a generally delayed increased risk of severe hypoglycemia.

Severe hypoglycemia in users of sulfonylurea antidiabetic agents and antihyperlipidemics

Drug-drug interactions causing severe hypoglycemia due to antidiabetic drugs is a major clinical and public health problem. We assessed whether sulfonylurea use with a statin or fibrate was associated with severe hypoglycemia. We conducted cohort studies of users of glyburide, glipizide, and glimepiride plus a statin or fibrate within a Medicaid population. The outcome was a validated, diagnosis-based algorithm for severe hypoglycemia. Among 592,872 persons newly exposed to a sulfonylurea+antihyperlipidemic, the incidence of severe hypoglycemia was 5.8/100 person-years. Adjusted hazard ratios (HRs) for sulfonylurea+statins were consistent with no association. Most overall HRs for sulfonylurea+fibrate were elevated, with sulfonylurea-specific adjusted HRs as large as 1.50 (95% confidence interval (CI): 1.24-1.81) for glyburide+gemfibrozil, 1.37 (95% CI: 1.11-1.69) for glipizide+gemfibrozil, and 1.63 (95% CI: 1.29-2.06) for glimepiride+fenofibrate. Concomitant therapy with a sulfonylurea and fibrate is associated with an often delayed increased rate of severe hypoglycemia.