Minireview: Challenges and opportunities in development of PPAR agonists

PPAR gamma and PGC-1alpha activators protect against diabetic nephropathy by suppressing the inflammation and NF-kappaB activation

AIM

Inflammation plays a critical role in the progression of diabetic nephropathy. Peroxisome proliferator-activated receptor gamma (PPARγ) and its coactivator PPARγ coactivator-1 alpha (PGC-1α) enhance mitochondrial biogenesis and cellular energy metabolism but inhibit inflammation. However, the molecular mechanism through which these two proteins cooperate in the kidney remains unclear. The aim of the present study was to investigate this mechanism.

METHODS

HK-2 human proximal tubular cells were stimulated by inflammatory factors, the expression of PPARγ and PGC-1α were determined via reverse transcription-quantitative polymerase chain reaction (PCR) and western blotting (WB), and DNA binding capacity was measured by an EMSA. Furthermore, db/db mice were used to establish a diabetic nephropathy model and were administered PPARγ and PGC-1α activators. Kidney injury was evaluated microscopically, and the inflammatory response was assessed via WB, immunohistochemistry and immunofluorescence staining. Besides, HK-2 cells were stimulated by high glucose and inflammatory factors with and without ZLN005 treatment, the expression of PPARγ, PGC-1α, p-p65 and p65 were determined via qPCR and WB.

RESULTS

Our results revealed that both TNF-α and IL-1β significantly decreased PPARγ and PGC-1 expression in vitro. Cytokines obviously decreased PPARγ DNA binding capacity. Moreover, we detected rapid activation of the NF-κB pathway in the presence of TNF-α or IL-1β. PPARγ and PGC-1α activators effectively protected against diabetic nephropathy and suppressed NF-κB expression both in db/db mice and HK-2 cells.

CONCLUSION

PPARγ and its coactivator PGC-1α actively participate in protecting against renal inflammation by regulating the NF-κB pathway, which highlights their potential as therapeutic targets for renal diseases.

Cladosporols and PPARγ: Same Gun, Same Bullet, More Targets

Several natural compounds have been found to act as PPARγ agonists, thus regulating numerous biological processes, including the metabolism of carbohydrates and lipids, cell proliferation and differentiation, angiogenesis, and inflammation. Recently, Cladosporols, secondary metabolites purified from the fungus Cladosporium tenuissimum, have been demonstrated to display an efficient ability to control cell proliferation in human colorectal and prostate cancer cells through a PPARγ-mediated modulation of gene expression. In addition, Cladosporols exhibited a strong anti-adipogenetic activity in 3T3-L1 murine preadipocytes, preventing their in vitro differentiation into mature adipocytes. These data interestingly point out that the interaction between Cladosporols and PPARγ, in the milieu of different cells or tissues, might generate a wide range of beneficial effects for the entire organism affected by diabetes, obesity, inflammation, and cancer. This review explores the molecular mechanisms by which the Cladosporol/PPARγ complex may simultaneously interfere with a dysregulated lipid metabolism and cancer promotion and progression, highlighting the potential therapeutic benefits of Cladosporols for human health.

PPARγ activation ameliorates cognitive impairment and chronic microglial activation in the aftermath of r-mTBI

Chronic neuroinflammation and microglial activation are key mediators of the secondary injury cascades and cognitive impairment that follow exposure to repetitive mild traumatic brain injury (r-mTBI). Peroxisome proliferator-activated receptor-γ (PPARγ) is expressed on microglia and brain resident myeloid cell types and their signaling plays a major anti-inflammatory role in modulating microglial responses. At chronic timepoints following injury, constitutive PPARγ signaling is thought to be dysregulated, thus releasing the inhibitory brakes on chronically activated microglia. Increasing evidence suggests that thiazolidinediones (TZDs), a class of compounds approved from the treatment of diabetes mellitus, effectively reduce neuroinflammation and chronic microglial activation by activating the peroxisome proliferator-activated receptor-γ (PPARγ). The present study used a closed-head r-mTBI model to investigate the influence of the TZD Pioglitazone on cognitive function and neuroinflammation in the aftermath of r-mTBI exposure. We revealed that Pioglitazone treatment attenuated spatial learning and memory impairments at 6 months post-injury and reduced the expression of reactive microglia and astrocyte markers in the cortex, hippocampus, and corpus callosum. We then examined whether Pioglitazone treatment altered inflammatory signaling mechanisms in isolated microglia and confirmed downregulation of proinflammatory transcription factors and cytokine levels. To further investigate microglial-specific mechanisms underlying PPARγ-mediated neuroprotection, we generated a novel tamoxifen-inducible microglial-specific PPARγ overexpression mouse line and examined its influence on microglial phenotype following injury. Using RNA sequencing, we revealed that PPARγ overexpression ameliorates microglial activation, promotes the activation of pathways associated with wound healing and tissue repair (such as: IL10, IL4 and NGF pathways), and inhibits the adoption of a disease-associated microglia-like (DAM-like) phenotype. This study provides insight into the role of PPARγ as a critical regulator of the neuroinflammatory cascade that follows r-mTBI in mice and demonstrates that the use of PPARγ agonists such as Pioglitazone and newer generation TZDs hold strong therapeutic potential to prevent the chronic neurodegenerative sequelae of r-mTBI.

Limitations in mitochondrial programming restrain the differentiation and maturation of human stem cell-derived β cells

Pluripotent stem cell (SC)-derived islets offer hope as a renewable source for β cell replacement for type 1 diabetes (T1D), yet functional and metabolic immaturity may limit their long-term therapeutic potential. Here, we show that limitations in mitochondrial transcriptional programming impede the formation and maturation of SC-derived β (SC-β) cells. Utilizing transcriptomic profiling, assessments of chromatin accessibility, mitochondrial phenotyping, and lipidomics analyses, we observed that SC-β cells exhibit reduced oxidative and mitochondrial fatty acid metabolism compared to primary human islets that are related to limitations in key mitochondrial transcriptional networks. Surprisingly, we found that reductions in glucose- stimulated mitochondrial respiration in SC-islets were not associated with alterations in mitochondrial mass, structure, or genome integrity. In contrast, SC-islets show limited expression of targets of PPARIZ and PPARγ, which regulate mitochondrial programming, yet whose functions in β cell differentiation are unknown. Importantly, treatment with WY14643, a potent PPARIZ agonist, induced expression of mitochondrial targets, improved insulin secretion, and increased the formation and maturation of SC-β cells both in vitro and following transplantation. Thus, mitochondrial programming promotes the differentiation and maturation of SC-β cells and may be a promising target to improve β cell replacement efforts for T1D.

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.

Targeting lipid-sensing nuclear receptors PPAR (α, γ, β/δ): HTVS and molecular docking/dynamics analysis of pharmacological ligands as potential pan-PPAR agonists

The global prevalence of obesity-related systemic disorders, including non-alcoholic fatty liver disease (NAFLD), and cancers are rapidly rising. Several of these disorders involve peroxisome proliferator-activated receptors (PPARs) as one of the key cell signaling pathways. PPARs are nuclear receptors that play a central role in lipid metabolism and glucose homeostasis. They can activate or suppress the genes responsible for inflammation, adipogenesis, and energy balance, making them promising therapeutic targets for treating metabolic disorders. In this study, an attempt has been made to screen novel PPAR pan-agonists from the ZINC database targeting the three PPAR family of receptors (α, γ, β/δ), using molecular docking and molecular dynamics (MD) simulations. The top scoring five ligands with strong binding affinity against all the three PPAR isoforms were eprosartan, canagliflozin, pralatrexate, sacubitril, olaparib. The ADMET analysis was performed to assess the pharmacokinetic profile of the top 5 molecules. On the basis of ADMET analysis, the top ligand was subjected to MD simulations, and compared with lanifibranor (reference PPAR pan-agonist). Comparatively, the top-scoring ligand showed better protein-ligand complex (PLC) stability with all the PPARs (α, γ, β/δ). When experimentally tested in in vitro cell culture model of NAFLD, eprosartan showed dose dependent decrease in lipid accumulation and oxidative damage. These outcomes suggest potential PPAR pan-agonist molecules for further experimental validation and pharmacological development, towards treatment of PPAR-mediated metabolic disorders.

PPARs in atherosclerosis: The spatial and temporal features from mechanism to druggable targets

BACKGROUND

Atherosclerosis is a chronic and complex disease caused by lipid disorder, inflammation, and other factors. It is closely related to cardiovascular diseases, the chief cause of death globally. Peroxisome proliferator-activated receptors (PPARs) are valuable anti-atherosclerosis targets that showcase multiple roles at different pathological stages of atherosclerosis and for cell types at different tissue sites.

AIM OF REVIEW

Considering the spatial and temporal characteristics of the pathological evolution of atherosclerosis, the roles and pharmacological and clinical studies of PPARs were summarized systematically and updated under different pathological stages and in different vascular cells of atherosclerosis. Moreover, selective PPAR modulators and PPAR-pan agonists can exert their synergistic effects meanwhile reducing the side effects, thereby providing novel insight into future drug development for precise spatial-temporal therapeutic strategy of anti-atherosclerosis targeting PPARs.

KEY SCIENTIFIC

Concepts of Review: Based on the spatial and temporal characteristics of atherosclerosis, we have proposed the importance of stage- and cell type-dependent precision therapy. Initially, PPARs improve endothelial cells' dysfunction by inhibiting inflammation and oxidative stress and then regulate macrophages' lipid metabolism and polarization to improve fatty streak. Finally, PPARs reduce fibrous cap formation by suppressing the proliferation and migration of vascular smooth muscle cells (VSMCs). Therefore, research on the cell type-specific mechanisms of PPARs can provide the foundation for space-time drug treatment. Moreover, pharmacological studies have demonstrated that several drugs or compounds can exert their effects by the activation of PPARs. Selective PPAR modulators (that specifically activate gene subsets of PPARs) can exert tissue and cell-specific effects. Furthermore, the dual- or pan-PPAR agonist could perform a better role in balancing efficacy and side effects. Therefore, research on cells/tissue-specific activation of PPARs and PPAR-pan agonists can provide the basis for precision therapy and drug development of PPARs.

Neuroimmune modulators as novel pharmacotherapies for substance use disorders

One promising avenue of research is the use of neuroimmune modulators to treat substance use disorders (SUDs). Neuroimmune modulators target the interactions between the nervous system and immune system, which have been found to play a crucial role in the development and maintenance of SUDs. Multiple classes of substances produce alterations to neuroimmune signaling and peripheral immune function, including alcohol, opioids, and psychostimulants Preclinical studies have shown that neuroimmune modulators can reduce drug-seeking behavior and prevent relapse in animal models of SUDs. Additionally, early-phase clinical trials have demonstrated the safety and feasibility of using neuroimmune modulators as a treatment for SUDs in humans. These therapeutics can be used as stand-alone treatments or as adjunctive. This review summarizes the current state of the field and provides future directions with a specific focus on personalized medicine.

Design and Synthesis of Novel Indole Ethylamine Derivatives as a Lipid Metabolism Regulator Targeting PPARα/CPT1 in AML12 Cells

Peroxisome proliferator-activated receptor alpha (PPARα) and carnitine palmitoyltransferase 1 (CPT1) are important targets of lipid metabolism regulation for nonalcoholic fatty liver disease (NAFLD) therapy. In the present study, a set of novel indole ethylamine derivatives (4, 5, 8, 9) were designed and synthesized. The target product (compound 9) can effectively activate PPARα and CPT1a. Consistently, in vitro assays demonstrated its impact on the lipid accumulation of oleic acid (OA)-induced AML12 cells. Compared with AML12 cells treated only with OA, supplementation with 5, 10, and 20 μM of compound 9 reduced the levels of intracellular triglyceride (by 28.07%, 37.55%, and 51.33%) with greater inhibitory activity relative to the commercial PPARα agonist fenofibrate. Moreover, the compound 9 supplementations upregulated the expression of hormone-sensitive triglyceride lipase (HSL) and adipose triglyceride lipase (ATGL) and upregulated the phosphorylation of acetyl-CoA carboxylase (ACC) related to fatty acid oxidation and lipogenesis. This dual-target compound with lipid metabolism regulatory efficacy may represent a promising type of drug lead for NAFLD therapy.

Pioneer Factor Foxa2 Mediates Chromatin Conformation Changes for Activation of Bile Acid Targets of FXR

BACKGROUND & AIMS

Transcription factors regulate gene expression that orchestrates liver physiology. Many bind at distal enhancers and chromatin looping is required to activate their targets. Chromatin architecture has been linked to essential functions of the liver, including metabolism and sexually dimorphic gene expression. We have previously shown that pioneer factor Foxa2 opens chromatin for binding of nuclear receptors farnesoid X receptor (FXR) and liver X receptor-α during acute ligand activation. FXR is activated by bile acids and deletion of Foxa2 in the liver results in intrahepatic cholestasis. We hypothesized that Foxa2 also enables chromatin conformational changes during ligand activation and performed genome-wide studies to test this hypothesis.

METHODS

We performed Foxa2 HiChIP (Hi-C and ChIP) to assess Foxa2-dependent long-range interactions in mouse livers treated with either vehicle control or FXR agonist GW4064.

RESULTS

HiChIP contact analysis shows that global chromatin interactions are dramatically increased during FXR activation. Ligand-treated livers exhibit extensive redistribution of topological associated domains and substantial increase in Foxa2-anchored loops, suggesting Foxa2 is involved in dynamic chromatin conformational changes. We demonstrate that chromatin conformation, including genome-wide interactions, topological associated domains, and intrachromosomal and interchromosomal Foxa2-anchored loops, drastically changes on addition of FXR agonist. Additional Foxa2 binding in ligand-activated state leads to formation of Foxa2-anchored loops, leading to distal interactions and activation of gene expression of FXR targets.

CONCLUSIONS

Ligand activation of FXR, and likely of related receptors, requires global changes in chromatin architecture. We determine a novel role for Foxa2 in enabling these conformational changes, extending its function in bile acid metabolism.

Peroxisome Proliferator-Activated Receptor α in Lipoprotein Metabolism and Atherosclerotic Cardiovascular Disease

Peroxisome proliferator-activated receptors (PPARs) are a group of ligand-binding transcription factors with pivotal action in regulating pleiotropic signaling pathways of energetic metabolism, immune responses and cell proliferation and differentiation. A significant body of evidence indicates that the PPARα receptor is an important modulator of plasma lipid and lipoprotein metabolism, with pluripotent effects influencing the lipid and apolipoprotein cargo of both atherogenic and antiatherogenic lipoproteins and their functionality. Clinical evidence supports an important role of PPARα agonists (fibric acid derivatives) in the treatment of hypertriglyceridemia and/or low high-density lipoprotein (HDL) cholesterol levels, although the effects of clinical trials are contradictory and point to a reduction in the risk of nonfatal and fatal myocardial infarction events. In this manuscript, we provide an up-to-date critical review of the existing relevant literature.

Oxazolidinones as versatile scaffolds in medicinal chemistry

Oxazolidinone is a five-member heterocyclic ring with several biological applications in medicinal chemistry. Among the three possible isomers, 2-oxazolidinone is the most investigated in drug discovery. Linezolid was pioneered as the first approved drug containing an oxazolidinone ring as the pharmacophore group. Numerous analogues have been developed since its arrival on the market in 2000. Some have succeeded in reaching the advanced stages of clinical studies. However, most oxazolidinone derivatives reported in recent decades have not reached the initial stages of drug development, despite their promising pharmacological applications in a variety of therapeutic areas, including antibacterial, antituberculosis, anticancer, anti-inflammatory, neurologic, and metabolic diseases, among other areas. Therefore, this review article aims to compile the efforts of medicinal chemists who have explored this scaffold over the past decades and highlight the potential of the class for medicinal chemistry.

PPAR-γ Agonist GW1929 Targeted to Macrophages with Dendrimer-Graphene Nanostars Reduces Liver Fibrosis and Inflammation

Macrophages play essential roles during the progression of chronic liver disease. They actively participate in the response to liver damage and in the balance between fibrogenesis and regression. The activation of the PPARγ nuclear receptor in macrophages has traditionally been associated with an anti-inflammatory phenotype. However, there are no PPARγ agonists with high selectivity for macrophages, and the use of full agonists is generally discouraged due to severe side effects. We designed dendrimer-graphene nanostars linked to a low dose of the GW1929 PPARγ agonist (DGNS-GW) for the selective activation of PPARγ in macrophages in fibrotic livers. DGNS-GW preferentially accumulated in inflammatory macrophages in vitro and attenuated macrophage pro-inflammatory phenotype. The treatment with DGNS-GW in fibrotic mice efficiently activated liver PPARγ signaling and promoted a macrophage switch from pro-inflammatory M1 to anti-inflammatory M2 phenotype. The reduction of hepatic inflammation was associated with a significant reduction in hepatic fibrosis but did not alter liver function or hepatic stellate cell activation. The therapeutic antifibrotic utility of DGNS-GW was attributed to an increased expression of hepatic metalloproteinases that allowed extracellular matrix remodeling. In conclusion, the selective activation of PPARγ in hepatic macrophages with DGNS-GW significantly reduced hepatic inflammation and stimulated extracellular matrix remodeling in experimental liver fibrosis.

Pioneer factor Foxa2 mediates chromatin conformation changes in ligand-dependent activation of nuclear receptor FXR

Activation of nuclear receptors, a family of ligand-dependent transcription factors, is used extensively in development of drug targets. We have previously shown that pioneer factor Foxa2 opens chromatin for binding of nuclear receptors FXR and LXRα during acute ligand activation. FXR is activated by bile acids and deletion of Foxa2 in the liver results in intrahepatic cholestasis. We hypothesized that Foxa2 also enables chromatin conformational changes during ligand activation. We performed Foxa2 HiChIP to assess Foxa2-dependent long-range interactions in mouse livers treated with either vehicle control or FXR agonist GW4064. HiChIP contact analysis shows that global chromatin interactions are dramatically increased during FXR activation. Ligand-treated livers exhibit extensive redistribution of topological associated domains (TAD and substantial increase in Foxa2-anchored loops, suggesting Foxa2 is involved in dynamic chromatin conformational changes. We demonstrate that chromatin conformation, including genome-wide interactions, TADs, intra-chromosomal and inter-chromosomal Foxa2-anchored loops, drastically changes upon addition of FXR agonist. Hence, we determine a novel role for Foxa2 in enabling these conformational changes, extending its function in bile acid metabolism.

The role of peroxisome proliferator-activated receptors in the modulation of hyperinflammation induced by SARS-CoV-2 infection: A perspective for COVID-19 therapy

Coronavirus disease 2019 (COVID-19) is a severe respiratory disease caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that affects the lower and upper respiratory tract in humans. SARS-CoV-2 infection is associated with the induction of a cascade of uncontrolled inflammatory responses in the host, ultimately leading to hyperinflammation or cytokine storm. Indeed, cytokine storm is a hallmark of SARS-CoV-2 immunopathogenesis, directly related to the severity of the disease and mortality in COVID-19 patients. Considering the lack of any definitive treatment for COVID-19, targeting key inflammatory factors to regulate the inflammatory response in COVID-19 patients could be a fundamental step to developing effective therapeutic strategies against SARS-CoV-2 infection. Currently, in addition to well-defined metabolic actions, especially lipid metabolism and glucose utilization, there is growing evidence of a central role of the ligand-dependent nuclear receptors and peroxisome proliferator-activated receptors (PPARs) including PPARα, PPARβ/δ, and PPARγ in the control of inflammatory signals in various human inflammatory diseases. This makes them attractive targets for developing therapeutic approaches to control/suppress the hyperinflammatory response in patients with severe COVID-19. In this review, we (1) investigate the anti-inflammatory mechanisms mediated by PPARs and their ligands during SARS-CoV-2 infection, and (2) on the basis of the recent literature, highlight the importance of PPAR subtypes for the development of promising therapeutic approaches against the cytokine storm in severe COVID-19 patients.

Identification of Selective PPAR-γ Modulators by Combining Pharmacophore Modeling, Molecular Docking, and Adipogenesis Assay

The clinically used glitazones (rosiglitazone and pioglitazone) for type 2 diabetes mellitus therapy have been linked to serious side effects such as fluid retention, congestive heart failure, weight gain, bone loss, and an increased risk of bladder cancer. The complete activation of PPAR-γ receptors in target tissues is linked to these effects. Many studies have demonstrated that partial PPAR-γ activators (GW0072, PAT5A, GQ16) give equivalent therapeutic benefits to full PPAR-γ agonists without the associated side effects. These breakthroughs cleared the path for the development of partial agonists or selective PPAR-γ modulators (SPPARγMs). This study combined pharmacophore modeling, molecular docking, and an adipogenesis experiment to identify thiazolidine analogs as SPPARMs/partial agonists. A custom library of 220 molecules was created and virtual screened to discover 90 compounds as SPPARγMs/ partial agonists. The chosen eight compounds were synthesized and tested for adipogenesis using 3T3L1 cell lines. These compounds' partial agonistic activity was evaluated in 3T3L1 cell lines by comparing their capacity to stimulate PPAR-γ mediated adipogenesis to that of a full agonist, rosiglitazone. The findings of the adipogenesis experiment demonstrate that all eight compounds examined had a partial potential to stimulate adipogenesis when compared to the full agonist, rosiglitazone. The current investigation identified eight possible PPAR-γ partial agonists or SPPARγMs that may be effective in the treatment of type 2 diabetes mellitus.

Anti-inflammatory effects and improved metabolic derangements in ob/ob mice by a newly synthesized prenylated benzopyran with pan-PPAR activity

BACKGROUND AND PURPOSE

Selective peroxisome proliferator-activated receptors (PPARs) are widely used to treat metabolic complications; however, the limited effect of PPARα agonists on glucose metabolism and the adverse effects associated with selective PPARγ activators have stimulated the development of novel pan-PPAR agonists to treat metabolic disorders. Here, we synthesized a new prenylated benzopyran (BP-2) and evaluated its PPAR-activating properties, anti-inflammatory effects and impact on metabolic derangements.

EXPERIMENTAL APPROACH

BP-2 was used in transactivation assays to evaluate its agonism to PPARα, PPARβ/δ and PPARγ. A parallel-plate flow chamber was employed to investigate its effect on TNFα-induced leukocyte-endothelium interactions. Flow cytometry and immunofluorescence were used to determine its effects on the expression of endothelial cell adhesion molecules (CAMs) and chemokines and p38-MAPK/NF-κB activation. PPARs/RXRα interactions were determined using a gene silencing approach. Analysis of its impact on metabolic abnormalities and inflammation was performed in ob/ob mice.

KEY RESULTS

BP-2 displayed strong PPARα activity, with moderate and weak activity against PPARβ/δ and PPARγ, respectively. In vitro, BP-2 reduced TNFα-induced endothelial ICAM-1, VCAM-1 and fractalkine/CX₃CL1 expression, suppressed mononuclear cell arrest via PPARβ/δ-RXRα interactions and decreased p38-MAPK/NF-κB activation. In vivo, BP-2 improved the circulating levels of glucose and triglycerides in ob/ob mice, suppressed T-lymphocyte/macrophage infiltration and proinflammatory markers in the liver and white adipose tissue, but increased the expression of the M2-like macrophage marker CD206.

CONCLUSION AND IMPLICATIONS

BP-2 emerges as a novel pan-PPAR lead candidate to normalize glycemia/triglyceridemia and minimize inflammation in metabolic disorders, likely preventing the development of further cardiovascular complications.

Discovery and Structure-Based Design of Potent Covalent PPARγ Inverse-Agonists and

The ligand-activated nuclear receptor peroxisome-proliferator-activated receptor-γ (PPARG or PPARγ) represents a potential target for a new generation of cancer therapeutics, especially in muscle-invasive luminal bladder cancer where PPARγ is a critical lineage driver. Here we disclose the discovery of a series of chloro-nitro-arene covalent inverse-agonists of PPARγ that exploit a benzoxazole core to improve interactions with corepressors NCOR1 and NCOR2. In vitro treatment of sensitive cell lines with these compounds results in the robust regulation of PPARγ target genes and antiproliferative effects. Despite their imperfect physicochemical properties, the compounds showed modest pharmacodynamic target regulation in vivo. Improvements to the in vitro potency and efficacy of BAY-4931 and BAY-0069 compared to those of previously described PPARγ inverse-agonists show that these compounds are novel tools for probing the in vitro biology of PPARγ inverse-agonism.

A New Fungal Triterpene from the Fungus Aspergillus flavus Stimulates Glucose Uptake without Fat Accumulation

Through activity-guided fractionation, a new triterpene (asperflagin, 1) was isolated as a PPAR-γ agonist from the jellyfish-derived fungus Aspergillus flavus. Asperflagin displayed selective and moderate transactivation effects on PPAR-γ in Ac2F rat liver cells. Based on further biological evaluation and molecular docking analysis, we postulated that asperflagin might function as a PPAR-γ partial agonist. This compound was calculated to display a typical PPAR-γ ligand–receptor interaction that is distinct from that of full agonistic antidiabetics such as rosiglitazone, and may retain the antidiabetic effect without accompanying weight gain. Weight gain and obesity are typical side effects of the PPAR-γ full agonist rosiglitazone, and lead to suboptimal outcomes in diabetic patients. Compared to rosiglitazone, asperflagin showed higher glucose uptake in HepG2 human liver cells at concentrations of 20 and 40 μM but induced markedly lower adipogenesis and lipid accumulation in 3T3-L1 preadipocytes. These results suggest that asperflagin may be utilized for further study on advanced antidiabetic leads.

The Molecular Mechanisms of Intestinal Inflammation and Fibrosis in Crohn’s Disease

Crohn’s disease (CD) is an inflammatory bowel disease (IBD) with repeated remissions and relapses. As the disease progresses, fibrosis and narrowing of the intestine occur, leading to severe complications such as intestinal obstruction. Endoscopic balloon dilatation, surgical stricture plasty, and bowel resection have been performed to treat intestinal stenosis. The clinical issue is that some patients with CD have a recurrence of intestinal stenosis even after the medical treatments. On the other hand, there exist no established medical therapies to prevent stenosis. With the progressive intestinal inflammation, cytokines and growth factors, including transforming growth factor (TGF-β), stimulate intestinal myofibroblasts, contributing to fibrosis of the intestine, smooth muscle hypertrophy, and mesenteric fat hypertrophy. Therefore, chronically sustained inflammation has long been considered a cause of intestinal fibrosis and stenosis. Still, even after the advent of biologics and tighter control of inflammation, intestinal fibrosis’s surgical rate has not necessarily decreased. It is essential to elucidate the mechanisms involved in intestinal fibrosis in CD from a molecular biological level to overcome clinical issues. Recently, much attention has been paid to several key molecules of intestinal fibrosis: peroxisome proliferator-activating receptor gamma (PPARγ), toll-like receptor 4 (TLR4), adherent-invasive Escherichia coli (AIEC), Th17 immune response, and plasminogen activator inhibitor 1 (PAI-1). As a major problem in the treatment of CD, the pathophysiology of patients with CD is not the same and varies depending on each patient. It is necessary to integrate these key molecules for a better understanding of the mechanism of intestinal inflammation and fibrosis.

Transcription Factors Involved in the Development and Prognosis of Cardiac Remodeling

To compensate increasing workload, heart must work harder with structural changes, indicated by increasing size and changing shape, causing cardiac remodeling. However, pathological and unlimited compensated cardiac remodeling will ultimately lead to decompensation and heart failure. In the past decade, numerous studies have explored many signaling pathways involved in cardiac remodeling, but the complete mechanism of cardiac remodeling is still unrecognized, which hinders effective treatment and drug development. As gene transcriptional regulators, transcription factors control multiple cellular activities and play a critical role in cardiac remodeling. This review summarizes the regulation of fetal gene reprogramming, energy metabolism, apoptosis, autophagy in cardiomyocytes and myofibroblast activation of cardiac fibroblasts by transcription factors, with an emphasis on their potential roles in the development and prognosis of cardiac remodeling.

Phenolic Lipids Derived from Cashew Nut Shell Liquid to Treat Metabolic Diseases

Metabolic diseases are increasing at staggering rates globally. The peroxisome proliferator-activated receptors (PPARα/γ/δ) are fatty acid sensors that help mitigate imbalances between energy uptake and utilization. Herein, we report compounds derived from phenolic lipids present in cashew nut shell liquid (CNSL), an abundant waste byproduct, in an effort to create effective, accessible, and sustainable drugs. Derivatives of anacardic acid and cardanol were tested for PPAR activity in HEK293 cell co-transfection assays, primary hepatocytes, and 3T3-L1 adipocytes. In vivo studies using PPAR-expressing zebrafish embryos identified CNSL derivatives with varying tissue-specific activities. LDT409 (23) is an analogue of cardanol with partial agonist activity for PPARα and PPARγ. Pharmacokinetic profiling showed that 23 is orally bioavailable with a half-life of 4 h in mice. CNSL derivatives represent a sustainable source of selective PPAR modulators with balanced intermediate affinities (EC₅₀ ∼ 100 nM to 10 μM) that provide distinct and favorable gene activation profiles for the treatment of diabetes and obesity.

Hypoxia enhances motility and EMT through the Na+/H+ exchanger NHE-1 in MDA-MB-231 breast cancer cells

Breast cancer metastasis is the leading cause of cancer-related deaths. Hypoxia in the tumor mass is believed to trigger cell migration, which is involved in a crucial process of breast cancer metastasis. However, the molecular mechanisms underlying aggressive behavior under hypoxic conditions have not been fully elucidated. Here, we demonstrate the significant motility of MDA-MB-231 cells cultured under hypoxic conditions compared to that of cells cultured under normoxic conditions. MDA-MB-231 cells under hypoxic conditions showed a significant increase in Na⁺/H⁺ exchanger isoform 1 (NHE1) expression level, which was observed to co-locate in lamellipodia formation. Inhibition of NHE1 significantly suppressed the intracellular pH and the expression of mesenchymal markers, thereby blocking the high migration activity in hypoxia. Moreover, treatment with ciglitazone, a potent and selective peroxisome proliferator-activated receptor γ (PPARγ) agonist, modulated hypoxia-enhanced motion in cells via the repression of NHE1. These findings highlight that NHE1 is required for migratory activity through the enhancement of epithelial-mesenchymal transition (EMT) in MDA-MB-231 cells under hypoxic conditions, and we propose new drug repurposing strategies targeting hypoxia based on NHE1 suppression by effective usage of PPARγ agonists.

Protocol for a preclinical systematic review and meta-analysis of pharmacological targeting of peroxisome proliferator-activated receptors in experimental renal injury

INTRODUCTION

Impaired lipid metabolism in the renal tubule plays a prominent role in the progression of renal fibrosis following acute kidney injury (AKI) and in chronic kidney disease (CKD). Peroxisome proliferator-activated receptors (PPARs) are promising druggable targets to mitigate renal fibrosis by redirecting metabolism, including restoration of fatty acid oxidation (FAO) capacity. We aim to synthesise evidence from preclinical studies of pharmacological PPAR targeting in experimental renal injury, and inform the design of future studies evaluating PPAR-mediated restoration of FAO in AKI and CKD.

METHODS AND ANALYSIS

Studies reporting on the impact of pharmacological PPAR modulation in animal models of renal injury will be collected from MEDLINE (Ovid), Embase and Web of Science databases. Predefined eligibility criteria will exclude studies testing medications which are not specific ligands of one or more PPARs and studies involving multimodal pharmacological treatment. The Systematic Review Centre for Laboratory Animal Experimentation risk of bias tool and Collaborative Approach to Meta-Analysis and Review of Animal Experimental Studies checklist will be used to assess quality of the included studies. Data extraction will be followed by a narrative synthesis of the data and meta-analysis where feasible. Analysis will be performed separately for AKI, CKD and renal transplant models. Subgroup analyses will be performed based on study design characteristics, PPAR isotype(s) targeted, and classes of PPAR-targeting medications used. Risk of publication bias will be assessed using funnel plotting, Egger's regression and trim-and-fill analysis.

ETHICS AND DISSEMINATION

Ethical approval is not required. Findings will be published in a peer-reviewed journal and presented at scientific meetings.

PROSPERO REGISTRATION NUMBER

CRD42021265550.

Pioglitazone Is a Mild Carrier-Dependent Uncoupler of Oxidative Phosphorylation and a Modulator of Mitochondrial Permeability Transition

Pioglitazone (PIO) is an insulin-sensitizing antidiabetic drug, which normalizes glucose and lipid metabolism but may provoke heart and liver failure and chronic kidney diseases. Both therapeutic and adverse effects of PIO can be accomplished through mitochondrial targets. Here, we explored the capability of PIO to modulate the mitochondrial membrane potential (ΔΨ_m) and the permeability transition pore (mPTP) opening in different models in vitro. ΔΨ_m was measured using tetraphenylphosphonium and the fluorescent dye rhodamine 123. The coupling of oxidative phosphorylation was estimated polarographically. The transport of ions and solutes across membranes was registered by potentiometric and spectral techniques. We found that PIO decreased ΔΨ_m in isolated mitochondria and intact thymocytes and the efficiency of ADP phosphorylation, particularly after the addition of Ca²⁺. The presence of the cytosolic fraction mitigated mitochondrial depolarization but made it sustained. Carboxyatractyloside diminished the PIO-dependent depolarization. PIO activated proton transport in deenergized mitochondria but not in artificial phospholipid vesicles. PIO had no effect on K⁺ and Ca²⁺ inward transport but drastically decreased the mitochondrial Ca²⁺-retention capacity and protective effects of adenine nucleotides against mPTP opening. Thus, PIO is a mild, partly ATP/ADP-translocase-dependent, uncoupler and a modulator of ATP production and mPTP sensitivity to Ca²⁺ and adenine nucleotides. These properties contribute to both therapeutic and adverse effects of PIO.

Immune treatments for alcohol use disorder: A translational framework

While the immune system is essential for survival, an excessive or prolonged inflammatory response, such as that resulting from sustained heavy alcohol use, can damage the host and contribute to psychiatric disorders. A growing body of literature indicates that the immune system plays a critical role in the development and maintenance of alcohol use disorder (AUD). As such, there is enthusiasm for treatments that can restore healthy levels of inflammation as a mechanism to reduce drinking and promote recovery. In this qualitative literature review, we provide a conceptual rationale for immune therapies and discuss progress in medications development for AUD focused on the immune system as a treatment target. This review is organized into sections based on primary signaling pathways targeted by the candidate therapies, namely: (a) toll-like receptors, (b) phosphodiesterase inhibitors, (c) peroxisome proliferator-activated receptors, (d) microglia and astrocytes, (e) other immune pharmacotherapies, and (f) behavioral therapies. As relevant within each section, we examine the basic biological mechanisms of each class of therapy and evaluate preclinical research testing the role of the therapy on mitigating alcohol-related behaviors in animal models. To the extent available, translational findings are reviewed with discussion of completed and ongoing randomized clinical trials and their findings to date. An applied and clinically focused approach is taken to identify the potential clinical applications of the various treatments reviewed. We conclude by delineating the most promising candidate treatments and discussing future directions by considering opportunities for immune treatment development and personalized medicine for AUD.

Pioneer factor Foxa2 enables ligand-dependent activation of type II nuclear receptors FXR and LXRα

Objective

Type II nuclear hormone receptors, including farnesoid X receptors (FXR), liver X receptors (LXR), and peroxisome proliferator-activated receptors (PPAR), which serve as drug targets for metabolic diseases, are permanently positioned in the nucleus and thought to be bound to DNA regardless of the ligand status. However, recent genome-wide location analysis showed that LXRα and PPARα binding in the liver is largely ligand-dependent. We hypothesized that pioneer factor Foxa2 evicts nucleosomes to enable ligand-dependent binding of type II nuclear receptors and performed genome-wide studies to test this hypothesis.

Methods

ATAC-Seq was used to profile chromatin accessibility; ChIP-Seq was performed to assess transcription factors (Foxa2, FXR, LXRα, and PPARα) binding; and RNA-Seq analysis determined differentially expressed genes in wildtype and Foxa2 mutants treated with a ligand (GW4064 for FXR, GW3965, and T09 for LXRα).

Results

We reveal that chromatin accessibility, FXR binding, LXRα occupancy, and ligand-responsive activation of gene expression by FXR and LXRα require Foxa2. Unexpectedly, Foxa2 occupancy is drastically increased when either receptor, FXR or LXRα, is bound by an agonist. In addition, co-immunoprecipitation experiments demonstrate that Foxa2 interacts with either receptor in a ligand-dependent manner, suggesting that Foxa2 and the receptor, bind DNA as an interdependent complex during ligand activation. Furthermore, PPARα binding is induced in Foxa2 mutants treated with FXR and LXR ligands, leading to the activation of PPARα targets.

Conclusions

Our model requires pioneering activity for ligand activation that challenges the existing ligand-independent binding mechanism. We also demonstrate that Foxa2 is required to achieve activation of the proper receptor – one that binds the added ligand – by repressing the activity of a competing receptor.

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Foxa2 opens chromatin for FXR and LXRα binding during acute ligand activation.

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Ligand-dependent activation of FXR & LXR-dependent gene expression requires Foxa2.

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Foxa2 interacts with FXR and LXRα in a ligand-dependent manner.

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Foxa2 restricts binding of competing receptor PPARα to ensure proper ligand-dependent activation of FXR and LXRα.

Discovery of novel modulators for the PPARα (peroxisome proliferator activated receptor α): Potential therapies for nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a severe liver disease causing serious liver complications, including nonalcoholic steatohepatitis (NASH). Nuclear receptor PPARα (peroxisome proliferator-activated receptor α) has drawn special attention recently as a potential developmental drug target to treat type-2 diabetes and related diseases due to its unique functions in regulating lipid metabolism, promoting triglyceride oxidation, and suppressing hepatic inflammation, raising interest in PPARα agonists as potential therapies for NAFLD. However, how PPARα coordinates potential treatment of NAFLD and NASH between various metabolic pathways is still obscure. Here, we show that the DY series of novel selective PPARα modulators activate PPARα by up-regulating PPARα target genes directly involved in NAFLD and NASH. The design, synthesis, docking studies, and in vitro and in vivo evaluation of the novel DY series of PPARα agonists are described.

Thiazolidinedione "Magic Bullets" Simultaneously Targeting PPARγ and HDACs: Design, Synthesis, and Investigations of their In Vitro and In Vivo Antitumor Effects

Monotargeting anticancer agents suffer from resistance and target nonspecificity concerns, which can be tackled with a multitargeting approach. The combined treatment with HDAC inhibitors and PPARγ agonists has displayed potential antitumor effects. Based on these observations, this work involves design and synthesis of molecules that can simultaneously target PPARγ and HDAC. Several out of 25 compounds inhibited HDAC4, and six compounds acted as dual-targeting agents. Compound 7i was the most potent, with activity toward PPARγ EC50 = 0.245 μM and HDAC4 IC50 = 1.1 μM. Additionally, compounds 7c and 7i were cytotoxic to CCRF-CEM cells (CC50 = 2.8 and 9.6 μM, respectively), induced apoptosis, and caused DNA fragmentation. Furthermore, compound 7c modulated the expression of c-Myc, cleaved caspase-3, and caused in vivo tumor regression in CCRF-CEM tumor xenografts. Thus, this study provides a basis for the rational design of dual/multitargeting agents that could be developed further as anticancer therapeutics.

The Role of Lipid Sensing Nuclear Receptors (PPARs and LXR) and Metabolic Lipases in Obesity, Diabetes and NAFLD

Obesity and type 2 diabetes mellitus (T2DM) are metabolic disorders characterized by metabolic inflexibility with multiple pathological organ manifestations, including non-alcoholic fatty liver disease (NAFLD). Nuclear receptors are ligand-dependent transcription factors with a multifaceted role in controlling many metabolic activities, such as regulation of genes involved in lipid and glucose metabolism and modulation of inflammatory genes. The activity of nuclear receptors is key in maintaining metabolic flexibility. Their activity depends on the availability of endogenous ligands, like fatty acids or oxysterols, and their derivatives produced by the catabolic action of metabolic lipases, most of which are under the control of nuclear receptors. For example, adipose triglyceride lipase (ATGL) is activated by peroxisome proliferator-activated receptor γ (PPARγ) and conversely releases fatty acids as ligands for PPARα, therefore, demonstrating the interdependency of nuclear receptors and lipases. The diverse biological functions and importance of nuclear receptors in metabolic syndrome and NAFLD has led to substantial effort to target them therapeutically. This review summarizes recent findings on the roles of lipases and selected nuclear receptors, PPARs, and liver X receptor (LXR) in obesity, diabetes, and NAFLD.

Bioactivity profiling of per- and polyfluoroalkyl substances (PFAS) identifies potential toxicity pathways related to molecular structure

Per- and polyfluoroalkyl substances (PFAS) are a broad class of hundreds of fluorinated chemicals with environmental health concerns due to their widespread presence and persistence in the environment. Several of these chemicals have been comprehensively studied for experimental toxicity, environmental fate and exposure, and human epidemiology; however, most chemicals have limited or no data available. To inform methods for prioritizing these data-poor chemicals for detailed toxicity studies, we evaluated 142 PFAS using an in vitro screening platform consisting of two multiplexed transactivation assays encompassing 81 diverse transcription factor activities and tested in concentration-response format ranging from 137 nM to 300 μM. Results showed activity for various nuclear receptors, including three known PFAS targets--specifically estrogen receptor alpha and peroxisome proliferator receptors alpha and gamma. We also report activity against the retinoid X receptor beta, the key heterodimeric partner of type II, non-steroidal nuclear receptors. Additional activities were found against the pregnane X receptor, nuclear receptor related-1 protein, and nuclear factor erythroid 2-related factor 2, a sensor of oxidative stress. Using orthogonal assay approaches, we confirmed activity of representative PFAS against several of these targets. Finally, we identified key PFAS structural features associated with nuclear receptor activity that can inform future predictive models for use in prioritizing chemicals for risk assessment and in the design of new structures devoid of biological activity.

PPARγ and Diabetes: Beyond the Genome and Towards Personalized Medicine

PURPOSE OF REVIEW

Full and partial synthetic agonists targeting the transcription factor PPARγ are contained in FDA-approved insulin-sensitizing drugs and used for the treatment of metabolic syndrome-related dysfunctions. Here, we discuss the association between PPARG genetic variants and drug efficacy, as well as the role of alternative splicing and post-translational modifications as contributors to the complexity of PPARγ signaling and to the effects of synthetic PPARγ ligands.

RECENT FINDINGS

PPARγ regulates the transcription of several target genes governing adipocyte differentiation and glucose and lipid metabolism, as well as insulin sensitivity and inflammatory pathways. These pleiotropic functions confer great relevance to PPARγ in physiological regulation of whole-body metabolism, as well as in the etiology of metabolic disorders. Accordingly, PPARG gene mutations, nucleotide variations, and post-translational modifications have been associated with adipose tissue disorders and the related risk of insulin resistance and type 2 diabetes (T2D). Moreover, PPARγ alternative splicing isoforms-generating dominant-negative isoforms mainly expressed in human adipose tissue-have been related to impaired PPARγ activity and adipose tissue dysfunctions. Thus, multiple regulatory levels that contribute to PPARγ signaling complexity may account for the beneficial as well as adverse effects of PPARγ agonists. Further targeted analyses, taking into account all these aspects, are needed for better deciphering the role of PPARγ in human pathophysiology, especially in insulin resistance and T2D. The therapeutic potential of full and partial PPARγ synthetic agonists underlines the clinical significance of this nuclear receptor. PPARG mutations, polymorphisms, alternative splicing isoforms, and post-translational modifications may contribute to the pathogenesis of metabolic disorders, also influencing the responsiveness of pharmacological therapy. Therefore, in the context of the current evidence-based trend to personalized diabetes management, we highlight the need to decipher the intricate regulation of PPARγ signaling to pave the way to tailored therapies in patients with insulin resistance and T2D.

Triclosan affects the expression of nitric oxide synthases (NOSs), peroxisome proliferator-activated receptor gamma (PPARγ), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in mouse neocortical neurons in vitro

Triclosan (TCS) is a well-known compound that can be found in disinfectants, personal care products. There is one publication concerning the involvement of PPARγ in the mechanism of action of TCS. It is known that activation of PPARγ regulates the expression of the NF-κB mediated inflammation by acting on nitric oxide synthase (NOS) genes. However, there are no studies demonstrating a relationship between the effects of TCS on the PPARγ signaling pathway, changes in NF-κB expression, and NOS isoform synthesis. Therefore, the aim of this study was to evaluate the effect of TCS on the expression of PPARγ, NF-κB, nNOS, iNOS, and eNOS in mouse neocortical neurons. In addition, the effects of co-administration of synthetic alpha-naphthoflavone (αNF) or beta-naphthoflavone (βNF) flavonoids and triclosan were investigated. Our results show that TCS alters PPARγ, NF-κB, iNOS, and eNOS expression in mouse neurons in vitro. After 48 h of exposure, TCS increased PPARγ expression and decreased NF-κB expression. Moreover, under the influence of TCS, the expression of iNOS was increased and at the same time the expression of nNOS was decreased, which was probably caused by high levels of ROS. The experiments have shown that both αNF and βNF are able to modulate the effects of TCS in primary cultures of mouse cortical neurons.

Ligand and structure-based computational designing of multi-target molecules directing FFAR-1, FFAR-4 and PPAR-G as modulators of insulin receptor activity

Multi-agent therapies are an important treatment modality in many diseases based on the assumption that combining agents may result in increased therapeutic benefit by overcoming the mechanism of resistance and providing superior efficiency. Extensively validated 3D pharmacophore models for free fatty acid receptor-1 (FFAR-1), free fatty acid receptor-4 (FFAR-4), and peroxisome proliferator-activated receptor-G (PPAR-G) was developed. The pharmacophore model for FFAR-1 (r² = 0.98, q² = 0.90) and PPAR-G (r² = 0.89, q² = 0.88) suggested that one hydrogen bond acceptor, one hydrogen bond donor, three aromatic rings, and two hydrophobic groups arranged in 3D space are essential for the binding affinity of FFAR-1 and PPAR-G inhibitors. Similarly, the pharmacophore model for FFAR-4 (r² = 0.92, q² = 0.87) suggested that the presence of a hydrogen bond acceptor, one negative atom, two aromatic rings, and three hydrophobic groups plays a vital role in the binding of an inhibitor of FFAR-4. These pharmacophore models allowed searches for novel FFAR-1, PPAR-G, and FFAR-4 triple inhibitors from multi-conformer 3D databases (Asinex). Finally, the twenty-five best hits were selected for molecular docking, to study the interaction of their complexes with all the proteins and final binding orientations of these molecules. After molecular docking, ten hits have been predicted to possess good binding affinity as per the Molecular Mechanics Generalized Born Surface Area (MM-GBSA) calculation for FFAR-1, FFAR-4, and PPAR-G which can be further investigated for its experimental in-vitro/in-vivo anti-diabetic activities.Communicated by Ramaswamy H. Sarma.

Cissus Quadrangularis enhances UCP1 mRNA, indicative of white adipocyte browning and decreases central obesity in humans in a randomized trial

Obesity is associated with the growth and expansion of adipocytes which could be decreased via several mechanisms. Cissus Quadrangularis (CQ) extract has been shown to reduce obesity in humans; however, its effect on human white adipocytes (hWA) has not been elucidated. This study aimed to investigate the effects of CQ on obesity, lipolysis, and browning of hWA. CQ treatment in obese humans significantly decreased waist circumference at week 4 and week 8 when compared with the baseline values (p < 0.05 all) and significantly decreased hip circumference at week 8 when compared with the baseline and week 4 values (p < 0.05 all). Serum leptin levels of the CQ-treated group were significantly higher at week 8 compared to baseline levels (p < 0.05). In hWA, glycerol release was reduced in the CQ-treated group when compared with the vehicle-treated group. In the browning experiment, pioglitazone, the PPAR-γ agonist, increased UCP1 mRNA when compared to vehicle (p < 0.01). Interestingly, 10, 100, and 1000 ng/ml CQ extract treatment on hWA significantly enhanced UCP1 expression in a dose-dependent manner when compared to pioglitazone treatment (p < 0.001 all). In conclusion, CQ decreased waist and hip circumferences in obese humans and enhanced UCP1 mRNA in hWA suggestive of its action via browning of hWA.

Diabetes and Its Complications: Therapies Available, Anticipated and Aspired

Worldwide, diabetes ranks among the ten leading causes of mortality. Prevalence of diabetes is growing rapidly in low and middle income countries. It is a progressive disease leading to serious co-morbidities, which results in increased cost of treatment and over-all health system of the country. Pathophysiological alterations in Type 2 Diabetes (T2D) progressed from a simple disturbance in the functioning of the pancreas to triumvirate to ominous octet to egregious eleven to dirty dozen model. Due to complex interplay of multiple hormones in T2D, there may be multifaceted approach in its management. The 'long-term secondary complications' in uncontrolled diabetes may affect almost every organ of the body, and finally may lead to multi-organ dysfunction. Available therapies are inconsistent in maintaining long term glycemic control and their long term use may be associated with adverse effects. There is need for newer drugs, not only for glycemic control but also for prevention or mitigation of secondary microvascular and macrovascular complications. Increased knowledge of the pathophysiology of diabetes has contributed to the development of novel treatments. Several new agents like Glucagon Like Peptide - 1 (GLP-1) agonists, Dipeptidyl Peptidase IV (DPP-4) inhibitors, amylin analogues, Sodium-Glucose transport -2 (SGLT- 2) inhibitors and dual Peroxisome Proliferator-Activated Receptor (PPAR) agonists are available or will be available soon, thus extending the range of therapy for T2D, thereby preventing its long term complications. The article discusses the pathophysiology of diabetes along with its comorbidities, with a focus on existing and novel upcoming antidiabetic drugs which are under investigation. It also dives deep to deliberate upon the novel therapies that are in various stages of development. Adding new options with new mechanisms of action to the treatment armamentarium of diabetes may eventually help improve outcomes and reduce its economic burden.

Herbal Decoction Divya-Peedantak-Kwath Alleviates Allodynia and Hyperalgesia in Mice Model of Chemotherapy-Induced Peripheral Neuropathy via Modulation in Cytokine Response

The widely used cancer treatment, chemotherapy, causes severe long-term neuropathic pain in 30–40% cases, the condition clinically known as chemotherapy-induced peripheral neuropathy (CIPN). Approved conventional analgesics are sometimes ineffective, while others like opioids have undesirable side effects like addiction, seizures, and respiratory malfunctioning. Tricyclic antidepressants and anticonvulsants, although exhibit anti-allodynic effects in neuropathy, also have unpleasant side effects. Thus, alternative medicines are being explored for CIPN treatment. Despite scattered reports on different extracts from different plants having potential anti-allodynic effects against CIPN, no established medicine or formulation of herbal origin exists. In this study, efficacy of an herbal decoction, formulated based on ancient medicinal principles and protocols for treating neuropathic pain, Divya-Peedantak-Kwath (DPK), has been evaluated in a paclitaxel (PTX)-induced peripheral neuropathic mouse model. We observed that DPK has prominent anti-allodynic and anti-hyperalgesic effects and acts as a nociceptive modulator for CIPN. With exhibited antioxidative effects, DPK restored the redox potential of the sciatic nerves to the normal. On histopathological evaluation, DPK prevented the PTX-induced lesions in the sciatic nerve, in a dose-dependent manner. It also prevented inflammation by modulating the levels of pro-inflammatory cytokines involved in CIPN pathogenesis. Our observations evinced that DPK can alleviate CIPN by attenuating oxidative stress and concomitant neuroinflammation through immune modulation.

Adipose tissue in health and disease

Adipose, or fat, tissue (AT) was once considered an inert tissue that primarily existed to store lipids, and was not historically recognized as an important organ in the regulation and maintenance of health. With the rise of obesity and more rigorous research, AT is now recognized as a highly complex metabolic organ involved in a host of important physiological functions, including glucose homeostasis and a multitude of endocrine capabilities. AT dysfunction has been implicated in several disease states, most notably obesity, metabolic syndrome and type 2 diabetes. The study of AT has provided useful insight in developing strategies to combat these highly prevalent metabolic diseases. This review highlights the major functions of adipose tissue and the consequences that can occur when disruption of these functions leads to systemic metabolic dysfunction.

Induction of Cyp450 enzymes by 4-thiazolidinone-based derivatives in 3T3-L1 cells in vitro

4-Thiazolidinones and related derivatives are regarded as privileged structures in medicinal chemistry and a source of new drug-like compounds. To date it is known that thiazolidinones are able to induce CYP1A1 activity in 3T3-L1 cells. Therefore, to extend the knowledge of the mechanism of thiazolidinones in the cell, four chemically synthesized heterocycles were tested on 3T3-L1 cells. The 3T3-L1 cells were exposed to Les-2194, Les-3640, Les-5935, and Les-6166. Our study showed that 1 μM βNF, Les-2194, and Les-6166 decreased the expression of Ahr mRNA. In turn, βNF, Les-2194, and Les-3640 increased the Cyp1a1 mRNA expression at the same time interval. On the other hand, Les-5935 was found to decrease the Cyp1a1 mRNA expression. Interestingly, the expression of Cyp1a2 mRNA was activated only by βNF and Les-2194. The expression of Cyp1b1 mRNA in the 3T3 cell line increased after the βNF and Les-2194 treatment but declined after the exposure to Les-5935 and Les-6166. Moreover, the Les-2194 and Les-5935 compounds were shown to increase the activity of EROD, MROD, and PROD. Les-3640 increased the activity of EROD and decreased the activity of PROD. In turn, the treatment with Les-6166 resulted in an increase in the activity of EROD and a decrease in the activity of MROD and PROD in the 3T3-L1 cells.

PPARγ Transcription Deficiency Exacerbates High-Fat Diet-Induced Adipocyte Hypertrophy and Insulin Resistance in Mice

Background

The transcriptional factor peroxisome proliferator–activated receptor γ (PPARγ) is an important therapeutic target for the treatment of type 2 diabetes. However, the role of the PPARγ transcriptional activity remains ambiguous in its metabolic regulation.

Methods

Based on the crystal structure of PPARγ bound with the DNA target of PPARγ response element (PPRE), Arg134, Arg135, and Arg138, three crucial DNA binding sites for PPARγ, were mutated to alanine (3RA), respectively. In vitro AlphaScreen assay and cell-based reporter assay validated that PPARγ 3RA mutant cannot bind with PPRE and lost transcriptional activity, while can still bind ligand (rosiglitazone) and cofactors (SRC1, SRC2, and NCoR). By using CRISPR/Cas9, we created mice that were heterozygous for PPARγ-3RA (PPARγ^3RA/+). The phenotypes of chow diet and high-fat diet fed PPARγ^3RA/+ mice were investigated, and the molecular mechanism were analyzed by assessing the PPARγ transcriptional activity.

Results

Homozygous PPARγ-3RA mutant mice are embryonically lethal. The mRNA levels of PPARγ target genes were significantly decreased in PPARγ^3RA/+ mice. PPARγ^3RA/+ mice showed more severe adipocyte hypertrophy, insulin resistance, and hepatic steatosis than wild type mice when fed with high-fat diet. These phenotypes were ameliorated after the transcription activity of PPARγ was restored by rosiglitazone, a PPARγ agonist.

Conclusion

The current report presents a novel mouse model for investigating the role of PPARγ transcription in physiological functions. The data demonstrate that the transcriptional activity plays an indispensable role for PPARγ in metabolic regulation.

A dietary anthocyanin cyanidin-3-O-glucoside binds to PPARs to regulate glucose metabolism and insulin sensitivity in mice

We demonstrate the mechanism by which C3G, a major dietary anthocyanin, regulates energy metabolism and insulin sensitivity. Oral administration of C3G reduced hepatic and plasma triglyceride levels, adiposity, and improved glucose tolerance in mice fed high-fat diet. Hepatic metabolomic analysis revealed that C3G shifted metabolite profiles towards fatty acid oxidation and ketogenesis. C3G increased glucose uptake in HepG2 cells and C2C12 myotubes and induced the rate of hepatic fatty acid oxidation. C3G directly interacted with and activated PPARs, with the highest affinity for PPARα. The ability of C3G to reduce plasma and hepatic triglycerides, glucose tolerance, and adiposity and to induce oxygen consumption and energy expenditure was abrogated in PPARα-deficient mice, suggesting that PPARα is the major target for C3G. These findings demonstrate that the dietary anthocyanin C3G activates PPARs, a master regulators of energy metabolism. C3G is an agonistic ligand of PPARs and stimulates fuel preference to fat.

In Silico Design, Synthesis and Evaluation of Novel Series of Benzothiazole- Based Pyrazolidinediones as Potent Hypoglycemic Agents

Background:

The discovery of novel ligand binding domain (LBD) of peroxisome proliferator- activated receptor γ (PPARγ) has recently attracted attention to few research groups in order to develop more potent and safer antidiabetic agents.

Objective:

This study is focused on docking-based design and synthesis of novel compounds combining benzothiazole and pyrazolidinedione scaffold as potential antidiabetic agents.

Methods:

Several benzothiazole-pyrazolidinedione hybrids were synthesized and tested for their in vivo anti-hyperglycemic activity. Interactions profile of title compounds against PPARγ was examined through molecular modelling approach.

Results:

All tested compounds exhibited anti-hyperglycemic activity similar or superior to the reference drug Rosiglitazone. Introducing chlorine atom and alkyl group at position-6 and -5 respectively on benzothiazole core resulted in enhancing the anti-hyperglycemic effect. Docking study revealed that such groups demonstrated favorable hydrophobic interactions with novel LBD Ω- pocket of PPARγ protein.

Conclusion:

Among the tested compounds, N-(6-chloro-5-methylbenzo[d]thiazol-2-yl-4-(4((3,5- dioxopyrazolidin-4-ylidene)methyl)phenoxy)butanamide 5b was found to be the most potent compound and provided valuable insights to further develop novel hybrids as anti-hyperglycemic agents.

Induction of UCP1 and thermogenesis by a small molecule via AKAP1/PKA modulation

Strategies to increase energy expenditure are an attractive approach to reduce excess fat storage and body weight to improve metabolic health. In mammals, uncoupling protein-1 (UCP1) in brown and beige adipocytes uncouples fatty acid oxidation from ATP generation in mitochondria and promotes energy dissipation as heat. We set out to identify small molecules that enhance UCP1 levels and activity using a high-throughput screen of nearly 12,000 compounds in mouse brown adipocytes. We identified a family of compounds that increase Ucp1 expression and mitochondrial activity (including un-coupled respiration) in mouse brown adipocytes and human brown and white adipocytes. The mechanism of action may be through compound binding to A kinase anchoring protein (AKAP) 1, modulating its localization to mitochondria and its interaction with protein kinase A (PKA), a known node in the β-adrenergic signaling pathway. In mice, the hit compound increased body temperature, UCP1 protein levels, and thermogenic gene expression. Some of the compound effects on mitochondrial function were UCP1- or AKAP1-independent, suggesting compound effects on multiple nodes of energy regulation. Overall, our results highlight a role for AKAP1 in thermogenesis, uncoupled respiration, and regulation energy balance.

Redox Regulation of PPARγ in Polarized Macrophages

The peroxisome proliferator-activated receptor (PPARγ) is a central mediator of cellular lipid metabolism and immune cell responses during inflammation. This is facilitated by its role as a transcription factor as well as a DNA-independent protein interaction partner. We addressed how the cellular redox milieu in the cytosol and the nucleus of lipopolysaccharide (LPS)/interferon-γ- (IFNγ-) and interleukin-4- (IL4-) polarized macrophages (MΦ) initiates posttranslational modifications of PPARγ, that in turn alter its protein function. Using the redox-sensitive GFP2 (roGFP2), we validated oxidizing and reducing conditions following classical and alternative activation of MΦ, while the redox status of PPARγ was determined via mass spectrometry. Cysteine residues located in the zinc finger regions (amino acid fragments AA 90-115, AA 116-130, and AA 160-167) of PPARγ were highly oxidized, accompanied by phosphorylation of serine 82 in response to LPS/IFNγ, whereas IL4-stimulation provoked minor serine 82 phosphorylation and less cysteine oxidation, favoring a reductive milieu. Mutating these cysteines to alanine to mimic a redox modification decreased PPARγ-dependent reporter gene transactivation supporting a functional shift of PPARγ associated with the MΦ phenotype. These data suggest distinct mechanisms for regulating PPARγ function based on the redox state of MΦ.

Polyacetylenes from Oplopanax horridus and Panax ginseng: Relationship between Structure and PPARγ Activation

Oplopanax horridus and Panax ginseng are members of the plant family Araliaceae, which is rich in structurally diverse polyacetylenes. In this work, we isolated and determined structures of 23 aliphatic C17 and C18 polyacetylenes, of which five are new compounds. Polyacetylenes have a suitable scaffold for binding to PPARγ, a ligand-activated transcription factor involved in metabolic regulation. Using a reporter gene assay, their potential was investigated to activate PPARγ. The majority of the polyacetylenes showed at least some PPARγ activity, among which oplopantriol B 18-acetate (1) and oplopantriol B (2) were the most potent partial PPARγ activators. By employing in silico molecular docking and comparing the activities of structural analogues, features are described that are involved in PPARγ activation, as well as in cytotoxicity. It was found that the type of C-1 to C-2 bond, the polarity of the terminal alkyl chain, and the backbone flexibility can impact bioactivity of polyacetylenes, while diol structures with a C-1 to C-2 double bond showed enhanced cytotoxicity. Since PPARγ activators have antidiabetic and anti-inflammatory properties, the present results may help explain some of the beneficial effects observed in the traditional use of O. horridus extracts. Additionally, they might guide the polyacetylene-based design of future PPARγ partial agonists.

Emerging targets and potential therapeutic agents in non-alcoholic fatty liver disease treatment

Nonalcoholic Fatty Liver Disease (NAFLD) is the most common chronic liver disease in the world, which is characterized by liver fat accumulation unrelated to excessive drinking. Indeed, it attracts growing attention and becomes a global health problem. Due to the complexity of the NAFLD pathogenic mechanism, no related drugs were approved by Food and Drug Administration (FDA) till now. However, it is encouraging that a series of candidate drugs have entered the clinical trial stage with expectation to treat NAFLD. In this review, we summarized the main pathways and pathogenic mechanisms of NAFLD, as well as introduced the main potential therapeutic targets and the corresponding compounds involved in metabolism, inflammation and fibrosis. Furthermore, we also discuss the progress of these compounds, such as drug design and optimization, the choice of pharmacological properties and druglikeness, and the analysis of structure-activity relationship. This review offers a medium on future drug design and development, to be beneficial to relevant studies.