The role of various peroxisome proliferator-activated receptors and their ligands in clinical practice

ω‑3 fatty acids in atherosclerotic cardiovascular disease (Review)

Atherosclerotic cardiovascular disease (ASCVD) is one of the most common chronic diseases in the world. Epidemiological evidence and clinical trials have shown that ω-3 fatty acids have a variety of promoting effects in reducing the risk of ASCVD, but different conclusions of large randomized controlled trials make their clinical use in the prevention and treatment of ASCVD controversial. The present review focuses on the pharmacological mechanism, clinical trials and evidence value of clinical applications of ω-3 fatty acids in order to provide theoretical and practical evidence for the clinical application strategy, and follow-up research and development of ω-3 fatty acids as anti-ASCVD drugs.

PPAR-γ regulates the polarization of M2 macrophages to improve the microenvironment for autologous fat grafting

The unpredictable survival rate of autologous fat grafting (AFG) seriously affects its clinical application. Improving the survival rate of AFG has become an unresolved issue in plastic surgery. Peroxisome proliferator-activated receptor-γ (PPAR-γ) regulates the adipogenic differentiation of adipocytes, but the functional mechanism in AFG remains unclear. In this study, we established an animal model of AFG and demonstrated the superior therapeutic effect of PPAR-γ regulation in the process of AFG. From day 3 after fat grafting, the PPAR-γ agonist rosiglitazone group consistently showed better adipose integrity, fewer oil cysts, and fibrosis. Massive macrophage infiltration was observed after 7 days. At the same time, M2 macrophages begin to appear. At day 14, M2 macrophages gradually became the dominant cell population, which suppressed inflammation and promoted revascularization and fat regeneration. In addition, transcriptome sequencing showed that the differentially expressed genes in the Rosiglitazone group were associated with the pathways of adipose regeneration, differentiation, and angiogenesis; these results provide new ideas for clinical treatment.

Gentiopicroside improves non-alcoholic steatohepatitis by activating PPARα and suppressing HIF1

Gentiopicroside (GPS) is a highly water-soluble small-molecule drug and the main bioactive secoiridoid glycoside of Gentiana scabra that has been shown to have hepatoprotective effects against non-alcoholic steatohepatitis (NASH), a form of non-alcoholic fatty liver disease (NAFLD) that can progress to cirrhosis and hepatocellular carcinoma. However, the effects of GPS on NASH and the underlying mechanisms remain obscure. Firstly, a high-fat, high-cholesterol (HFHC) diet and a high-sugar solution containing d-fructose and d-glucose were used to establish a non-alcoholic steatohepatitis (NASH) mice model. Secondly, we confirmed GPS supplementation improve metabolic abnormalities and reduce inflammation in NASH mice induced by HFHC and high-sugar solution. Then we used metabolomics to investigate the mechanisms of GPS in NASH mice. Metabolomics analysis showed GPS may work through the Peroxisome Proliferator-Activated Receptor (PPAR) signaling pathway and glycine, serine, and threonine metabolism. Functional metabolites restored by GPS included serine, glycine, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Western blot and qRT-PCR analysis confirmed GPS improve NASH by regulating PPARα and Hypoxia-Inducible Factor-1α (HIF-1α) signaling pathways. In vitro, studies further demonstrated EPA and DHA enhance fatty acid oxidation through the PPARα pathway, while serine and glycine inhibit oxidative stress through the HIF-1α pathway in palmitic acid-stimulated HepG2 cells. Our results suggest GPS's anti-inflammatory and anti-steatosis effects in NASH progression are related to the suppression of HIF-1α through the restoration of L-serine and glycine and the activation of PPARα through increased EPA and DHA.

Lipid-lowering drugs and cancer: an updated perspective

Statins and non-statin medications used for the management of dyslipidemia have been shown to possess antitumor properties. Since the use of these drugs has steadily increased over the past decades, more knowledge is required about their relationship with cancer. Lipid-lowering agents are heterogeneous compounds; therefore, it remains to be revealed whether anticancer potential is a class effect or related to them all. Here, we reviewed the literature on the influence of lipid-lowering medications on various types of cancer during development or metastasis. We also elaborated on the underlying mechanisms associated with the anticancer effects of antihyperlipidemic agents by linking the reported in vivo and in vitro studies.

Effect of Fibrate Treatment on Circulating Adipokine Levels: A Systematic Review and Meta-analysis of Randomized Clinical Trials

BACKGROUND

Fibrates are widely used in the treatment of dyslipidemia and associated metabolic abnormalities; however, their effects on adipokines are unclear.

AIM OF THE STUDY

This meta-analysis of clinical trials aimed to evaluate the effect of fibrates on circulating adipokine levels.

METHODS

Only randomized controlled trials investigating the impact/effect of fibrate treatment on circulating adipokine levels were included from searches in PubMed-Medline, SCOPUS, ClinicalTrials.gov, Web of Science, and Google Scholar databases. A random effects model and the generic inverse variance method were used for the meta-analysis. Sensitivity analysis was conducted using the leave-one-out method.

RESULTS

This meta-analysis of 22 clinical trials showed a significant reduction on/in leptin (WMD: -1.58 ng/mL, 95% CI: -2.96, -0.20, p = 0.02, I2 = 0%), plasminogen activator inhibitor-1 (PAI-1) (WMD: -13.86 ng/mL, 95% CI: -26.70, -1.03, p = 0.03, I2 = 99%), and visfatin (WMD: -1.52 ng/mL, 95% CI: -2.49, -0.56, p = 0.002, I2 = 0%) after fibrate therapy; no significant effect was observed on adiponectin (WMD: -0.69 µg/ml, 95% CI: -1.40, 0.02, p = 0.06, I2 = 83%) and resistin (WMD: -2.27 ng/mL, 95% CI: -7.11, 2.57, p = 0.36, I2 = 0%). The sensitivity analysis was robust only for visfatin, while the effect size was sensitive to one arm for leptin, four for adiponectin, and two for PAI-1.

CONCLUSION

This meta-analysis showed that fibrate treatment significantly improves adipokine levels with a decrease in leptin, PAI-1, and visfatin, suggesting potential additional clinical therapeutic benefits through/of fibrate treatment on adipose tissue.

Therapeutic effects of anti-diabetic drugs on traumatic brain injury

AIMS

In this narrative review, we have analyzed and synthesized current studies relating to the effects of anti-diabetic drugs on traumatic brain injury (TBI) complications.

METHODS

Eligible studies were collected from Scopus, Google Scholar, PubMed, and Cochrane Library for clinical, in-vivo, and in-vitro studies published on the impact of anti-diabetic drugs on TBI.

RESULTS

Traumatic brain injury (TBI) is a serious brain disease that is caused by any type of trauma. The pathophysiology of TBI is not yet fully understood, though physical injury and inflammatory events have been implicated in TBI progression. Several signaling pathways are known to play pivotal roles in TBI injuries, including Nuclear factor erythroid 2-related factor 2 (Nrf2), High mobility group box 1 protein/Nuclear factor kappa B (HMGB1/NF-κB), Adiponectin, Mammalian Target of Rapamycin (mTOR), Toll-Like Receptor (TLR), Wnt/β-catenin, Janus Kinase/Signal Transducers and Activators of Transcription (JAK/STAT), Nod-like receptor protein3 (NLRP3) inflammasome, Phosphoglycerate kinase 1/Kelch-like ECH-associated protein 1 (PGK1/KEAP1)/Nrf2, and Mitogen-activated protein kinase (MAPK) . Recent studies suggest that oral anti-diabetic drugs such as biguanides, thiazolidinediones (TZDs), sulfonylureas (SUs), sodium-glucose cotransporter-2 inhibitors (SGLT2is), dipeptidyl peptidase-4 inhibitors (DPPIs), meglitinides, and alpha-glucosidase inhibitors (AGIs) could have beneficial effects in the management of TBI complications. These drugs may downregulate the inflammatory pathways and induce antioxidant signaling pathways, thus alleviating complications of TBI.

CONCLUSION

Based on this comprehensive literature review, antidiabetic medications might be considered in the TBI treatment protocol. However, evidence from clinical trials in patients with TBI is still warranted.

Peroxisome proliferator-activated receptors: A key link between lipid metabolism and cancer progression

Lipids represent the essential components of membranes, serve as fuels for high-energy processes, and play crucial roles in signaling and cellular function. One of the key hallmarks of cancer is the reprogramming of metabolic pathways, especially abnormal lipid metabolism. Alterations in lipid uptake, lipid desaturation, de novo lipogenesis, lipid droplets, and fatty acid oxidation in cancer cells all contribute to cell survival in a changing microenvironment by regulating feedforward oncogenic signals, key oncogenic functions, oxidative and other stresses, immune responses, or intercellular communication. Peroxisome proliferator-activated receptors (PPARs) are transcription factors activated by fatty acids and act as core lipid sensors involved in the regulation of lipid homeostasis and cell fate. In addition to regulating whole-body energy homeostasis in physiological states, PPARs play a key role in lipid metabolism in cancer, which is receiving increasing research attention, especially the fundamental molecular mechanisms and cancer therapies targeting PPARs. In this review, we discuss how cancer cells alter metabolic patterns and regulate lipid metabolism to promote their own survival and progression through PPARs. Finally, we discuss potential therapeutic strategies for targeting PPARs in cancer based on recent studies from the last five years.

Integrating network pharmacology and animal experimental validation to investigate the action mechanism of oleanolic acid in obesity

BACKGROUND

Obesity, a condition associated with the development of widespread cardiovascular disease, metabolic disorders, and other health complications, has emerged as a significant global health issue. Oleanolic acid (OA), a pentacyclic triterpenoid compound that is widely distributed in various natural plants, has demonstrated potential anti-inflammatory and anti-atherosclerotic properties. However, the mechanism by which OA fights obesity has not been well studied.

METHOD

Network pharmacology was utilized to search for potential targets and pathways of OA against obesity. Molecular docking and molecular dynamics simulations were utilized to validate the interaction of OA with core targets, and an animal model of obesity induced by high-fat eating was then employed to confirm the most central of these targets.

RESULTS

The network pharmacology study thoroughly examined 42 important OA targets for the treatment of obesity. The key biological processes (BP), cellular components (CC), and molecular functions (MF) of OA for anti-obesity were identified using GO enrichment analysis, including intracellular receptor signaling, intracellular steroid hormone receptor signaling, chromatin, nucleoplasm, receptor complex, endoplasmic reticulum membrane, and RNA polymerase II transcription Factor Activity. The KEGG/DAVID database enrichment study found that metabolic pathways, PPAR signaling pathways, cancer pathways/PPAR signaling pathways, insulin resistance, and ovarian steroidogenesis all play essential roles in the treatment of obesity and OA. The protein-protein interaction (PPI) network was used to screen nine main targets: PPARG, PPARA, MAPK3, NR3C1, PTGS2, CYP19A1, CNR1, HSD11B1, and AGTR1. Using molecular docking technology, the possible binding mechanism and degree of binding between OA and each important target were validated, demonstrating that OA has a good binding potential with each target. The molecular dynamics simulation's Root Mean Square Deviation (RMSD), and Radius of Gyration (Rg) further demonstrated that OA has strong binding stability with each target. Additional animal studies confirmed the significance of the core target PPARG and the core pathway PPAR signaling pathway in OA anti-obesity.

CONCLUSION

Overall, our study utilized a multifaceted approach to investigate the value and mechanisms of OA in treating obesity, thereby providing a novel foundation for the identification and development of natural drug treatments.

Impact of Statin or Fibrate Therapy on Homocysteine Concentrations: A Systematic Review and Meta-analysis

INTRODUCTION

Statins and fibrates are two lipid-lowering drugs used in patients with dyslipidemia. This systematic review and meta-analysis were conducted to determine the magnitude of the effect of statin and fibrate therapy on serum homocysteine levels.

METHODS

A search was undertaken of the PubMed, Scopus, Web of Science, Embase, and Google Scholar electronic databases up to 15 July 2022. Primary endpoints focused on plasma homocysteine levels. Data were quantitatively analyzed using fixed or random- effect models, as appropriate. Subgroup analyses were conducted based on the drugs and hydrophilic-lipophilic balance of statins.

RESULTS

After screening 1134 papers, 52 studies with a total of 20651 participants were included in the meta-analysis. The analysis showed a significant decrease in plasma homocysteine levels after statin therapy (WMD: -1.388 μmol/L, 95% CI: [-2.184, -0.592], p = 0.001; I2 = 95%). However, fibrate therapy significantly increased plasma homocysteine levels (WMD: 3.459 μmol/L, 95% CI: [2.849, 4.069], p < 0.001; I2 = 98%). The effect of atorvastatin and simvastatin depended on the dose and duration of treatment (atorvastatin [coefficient: 0.075 [0.0132, 0.137]; p = 0.017, coefficient: 0.103 [0.004, 0.202]; p = 0.040, respectively] and simvastatin [coefficient: -0.047 [-0.063, -0.031]; p < 0.001, coefficient: 0.046 [0.016, 0.078]; p = 0.004]), whereas the effect of fenofibrate persisted over time (coefficient: 0.007 [-0.011, 0.026]; p = 0.442) and was not altered by a change in dosage (coefficient: -0.004 [-0.031, 0.024]; p = 0.798). In addition, the greater homocysteine- lowering effect of statins was associated with higher baseline plasma homocysteine concentrations (coefficient: -0.224 [-0.340, -0.109]; p < 0.001).

CONCLUSION

Fibrates significantly increased homocysteine levels, whereas statins significantly decreased them.

An update on the therapeutic role of RNAi in NAFLD/NASH

Unhealthy lifestyles have given rise to a growing epidemic of metabolic liver diseases, including nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). NAFLD often occurs as a consequence of obesity, and currently, there is no FDA-approved drug for its treatment. However, therapeutic oligonucleotides, such as RNA interference (RNAi), represent a promising class of pharmacotherapy that can target previously untreatable conditions. The potential significance of RNAi in maintaining physiological homeostasis, understanding pathogenesis, and improving metabolic liver diseases, including NAFLD, is discussed in this article. We explore why NAFLD/NASH is an ideal target for therapeutic oligonucleotides and provide insights into the delivery platforms of RNAi and its therapeutic role in addressing NAFLD/NASH.

Design, synthesis, and biological evaluation of deuterated indolepropionic acid derivatives as novel long-acting pan PPARα/γ/δ agonists

Metabolic syndrome is a complex disease with diverse symptoms, but current pharmacological interventions have limited efficacy. Indeglitazar, a pan-agonist targeting the three-peroxisome proliferator activated receptors (PPAR), exhibits significant therapeutic effects on both diabetic and fatty liver animal models. However, its short half-life limits the in vivo efficacy, which might be attributed to the β-oxidation of indolepropionic acid at Indeglitazar. To overcome this metabolic instability, two deuterium atoms were introduced to the α-position of indolepropionic acid to block the β-oxidation. In this study, several deuterated derivatives were found to sustain PPARs activity and extend the half-life of liver microsomes. In oral glucose tolerance tests, I-1 exhibited the strongest glucose-lowering effect on ob/ob mice in this series. In db/db mice, I-1 reduced lipid levels, liver steatosis and promoted UCP1 expression in white adipose tissue. Mechanistic studies further revealed that I-1 exerts stronger effects than Indeglitazar on the regulation of genes related to lipid metabolism, mitochondrial function, and oxidative stress. Furthermore, I-1 significantly reduced liver steatosis, hepatocellular ballooning, inflammation, and fibrosis in NASH model induced by HFD + CCl4, and even exerted better therapeutic effect than that of Indeglitazar. With the above attractive efficacy, deuterated derivative I-1 is considered as a promising treatment for metabolic syndrome.

Inflammation-induced nitric oxide suppresses PPARα expression and function via downregulation of Sp1 transcriptional activity in adipocytes

The activation of peroxisome proliferator-activated receptor alpha (PPARα), a ligand-dependent transcription factor that regulates lipid oxidation-related genes, has been employed to treat hyperlipidemia. Emerging evidence indicates that Ppara gene expression decreases in adipose tissue under obese conditions; however, the underlying molecular mechanisms remain elusive. Here, we demonstrate that nitric oxide (NO) suppresses Ppara expression by regulating its promoter activity via suppression of specificity protein 1 (Sp1) transcriptional activity in adipocytes. NO derived from lipopolysaccharide (LPS) -activated macrophages or a NO donor (NOR5) treatment, suppressed Ppara mRNA expression in 10T1/2 adipocytes. In addition, Ppara transcript levels were reduced in the white adipose tissue (WAT) in both acute and chronic inflammation mouse models; however, such suppressive effects were attenuated via a nitric oxide synthase 2 (NOS2) inhibitor. Endoplasmic reticulum (ER) stress inhibitors attenuated the NO-induced repressive effects on Ppara gene expression in 10T1/2 adipocytes. Promoter mutagenesis and chromatin immunoprecipitation assays revealed that NO decreased the Sp1 occupancy in the proximal promoter regions of the Ppara gene, which might partially result from the reduced Sp1 expression levels by NO. This study delineated the molecular mechanism that modulates Ppara gene transcription upon NO stimulation in white adipocytes, suggesting a possible mechanism for the transcriptional downregulation of Ppara in WAT under obese conditions.

Catecholamine Derivatives: Natural Occurrence, Structural Diversity, and Biological Activity

Catecholamines (CAs) are aromatic amines containing a 3,4-dihydroxyphenyl nucleus and an amine side chain. Representative CAs included the endogenous neurotransmitters epinephrine, norepinephrine, and dopamine. CAs and their derivatives are good resources for the development of sympathomimetic or central nervous system drugs, while they also provide ligands important for G-protein coupled receptor (GPCR) research. CAs are of broad interest in the fields of chemical, biological, medical, and material sciences due to their high adhesive capacities, chemical reactivities, metal-chelating abilities, redox activities, excellent biocompatibilities, and ease of degradability. Herein, we summarize CAs derivatives isolated and identified from microorganisms, plants, insects, and marine invertebrates in recent decades, alongside their wide range of reported biological activities. The aim of this review is to provide an overview of the structural and biological diversities of CAs, the regularity of their natural occurrences, and insights toward future research and development pertinent to this important class of naturally occurring compounds.

Dry heat whole Sorghum BRS 305 flour modulate satiety and improves antioxidant response in brain of Wistar rats fed with high-fat high-fructose diet

Sorghum BRS 305 (Sorghum bicolor L. Moench) is a cereal with high tannins and anthocyanins content and keep better the resistant starch when submitted to dry heat treatment. Our objective was to investigate the effects of BRS 305 dry heat treatment whole sorghum flour on satiety and antioxidant response in brain and adipose tissue of Wistar rats fed with a high fat high fructose diet (HFHF). Male Wistar rats were divided in two groups: control (n = 8) and HFHF (n = 16) for eight weeks. After, animals of HFHF group were divided: HFHF (n = 8) and HFHF + BRS 305 sorghum whole flour (n = 8), for 10 weeks. Sorghum consumption reduced gene expression of leptin, resistin, and endocannabinoid receptor 1 type (CB1) in adipose and brain tissues compared to HFHF group. In brain, sorghum consumption also promotes reduction in neuropeptide Y (NPY) gene expression. BRS305 sorghum consumption improved gene expression of sirtuin-1 (SIRT1) in adipose tissue, and in the brain increased heat shock protein 72 (HSP72), erythroid-derived nuclear factor 2 (NRF2), peroxisome proliferator-activated receptor alpha (PPARα), superoxide dismutase (SOD) and catalase activity compared to HFHF. In silicoanalysis showed interaction with PPARα, CB1, and leptin receptors. Advanced glycation end products (AGEs) concentrations in group HFHF + sorghum did not differ from HFHF group. Advanced glycation end products receptors (RAGEs) concentrations did not differ among experimental groups. Then, BRS 305 sorghum submitted to dry treatment was able to modulate gene expression of markers related to satiety and improve antioxidant capacity of rats fed with HFHF diet.

Structural Identification of Impurities in Pioglitazone Hydrochloride Preparations by 2D-UHPLC-Q-Exactive Orbitrap HRMS and Their Toxicity Prediction

Pharmaceutical companies and regulatory agencies have more and more concerns for impurities in pharmaceuticals and their toxicity. In this work, heart-cutting two-dimensional ultrahigh-performance liquid chromatography (2D-UHPLC) in combination with high-resolution mass spectrometry (HRMS) was used, setting HRMS as positive mode of electrospray ionization to identify five impurities in pioglitazone hydrochloride preparations. With the heart-cutting 2D-UHPLC and online desalting technique, the structures of five impurities were deduced in an analysis of MSn data. And three of them, Impurity-2, Impurity-3, and Impurity-5, have never been reported before. The fragmentation patterns of five impurities were proposed on a basis of accurate mass and fragment ions in this study. Since the toxicity of impurities is relevant to their structures, toxicology of all five impurities was predicted by three software tools, and the result showed that these compounds have good safety profile.

Beyond energy and growth: the role of metabolism in developmental signaling, cell behavior and diapause

Metabolism is crucial for development through supporting cell growth, energy production, establishing cell identity, developmental signaling and pattern formation. In many model systems, development occurs alongside metabolic transitions as cells differentiate and specialize in metabolism that supports new functions. Some cells exhibit metabolic flexibility to circumvent mutations or aberrant signaling, whereas other cell types require specific nutrients for developmental progress. Metabolic gradients and protein modifications enable pattern formation and cell communication. On an organism level, inadequate nutrients or stress can limit germ cell maturation, implantation and maturity through diapause, which slows metabolic activities until embryonic activation under improved environmental conditions.

Role of Human Monocarboxylate Transporter 1 (hMCT1) and 4 (hMCT4) in Tumor Cells and the Tumor Microenvironment

In recent years, the abnormal glucose metabolism of tumor cells has attracted increasing attention. Abnormal glucose metabolism is closely related to the occurrence and development of tumors. Monocarboxylate transporters (MCTs) transport the sugar metabolites lactic acid and pyruvate, which affect glucose metabolism and tumor progression in a variety of ways. Thus, research has recently focused on MCTs and their potential functions in cancer. The MCT superfamily consists of 14 members. MCT1 and MCT4 play a crucial role in the maintenance of intracellular pH in tumor cells by transporting monocarboxylic acids (such as lactate, pyruvate and butyrate). MCT1 and MCT4 are highly expressed in a variety of tumor cells and are involved the proliferation, invasion and migration of tumor cells, which are closely related to the prognosis of cancer. Because of their important functions in tumor cells, MCT1 and MCT4 have become potential targets for cancer treatment. In this review, we focus on the structure, function and regulation of MCT1 and MCT4 and discuss the developed inhibitors of MCT1 and MCT4 to provide more comprehensive information that might aid in the development of strategies targeting MCTs in cancer.

Integrated biomarker profiling of the metabolome associated with type 2 diabetes mellitus among Tibetan in China

INTRODUCTION

Metabolomic signatures of type 2 diabetes mellitus (T2DM) in Tibetan Chinese population, a group with high diabetes burden, remain largely unclear. Identifying the serum metabolite profile of Tibetan T2DM (T-T2DM) individuals may provide novel insights into early T2DM diagnosis and intervention.

METHODS

Hence, we conducted untargeted metabolomics analysis of plasma samples from a retrospective cohort study with 100 healthy controls and 100 T-T2DM patients by using liquid chromatography-mass spectrometry.

RESULTS

The T-T2DM group had significant metabolic alterations that are distinct from known diabetes risk indicators, such as body mass index, fasting plasma glucose, and glycosylated hemoglobin levels. The optimal metabolite panels for predicting T-T2DM were selected using a tenfold cross-validation random forest classification model. Compared with the clinical features, the metabolite prediction model provided a better predictive value. We also analyzed the correlation of metabolites with clinical indices and found 10 metabolites that were independently predictive of T-T2DM.

CONCLUSION

By using the metabolites identified in this study, we may provide stable and accurate biomarkers for early T-T2DM warning and diagnosis. Our study also provides a rich and open-access data resource for optimizing T-T2DM management.

Design, synthesis and anti-NASH effect evaluation of novel GFT505 derivatives in vitro and in vivo

Non-alcoholic fatty liver disease (NAFLD) is emerging as the largest burden of chronic liver disease worldwide. Nonalcoholic steatohepatitis (NASH) is a progressive form of NAFLD that can progress to cirrhosis and hepatocellular carcinoma. Unfortunately, current treatment options for NASH are very limited. Among the multiple pathways of NASH, peroxisome proliferators-activated receptors (PPARS) are recognized as an important and effective target. GFT 505 is a dual excitement agent for the treatment of PPAR-α/δ for the treatment of NASH. However, its activity and toxicity need to be further improved. Therefore, here we would like to report the design, synthesis and biological evaluation of 11 GFT 505 derivatives. The initial cytotoxicity through proliferation activity of HepG2 cells and in vitro anti-NASH activity evaluation demonstrated that under the same concentration, the compound 3d possess significantly lower cytotoxicity and better anti-NASH activity than that of GFT 505. Moreover, Molecular docking also shows that 3d and PPAR-α/δ can form a stable hydrogen bond and have the lowest binding energy. Therefore this novel molecule 3d was selected to go further in vivo investigation. Methionine-choline deficiency (MCD) induced C57BL/6J NASH model mice was used for the in vivo biological experiments and the compound 3d demostrated lower liver toxicity than that of GFT 505 in the body at the same dose, and it did more effectively improve hyperlipidemia, liver fat degeneration and liver inflammation as well as significantly enhance the content of the GSH which is inportant for the liver protection. This study suggested that the compound 3d is a very promising lead compound for the treatment of NASH.

Towards a Unified Approach in Autoimmune Fibrotic Signalling Pathways

Autoimmunity is a chronic process resulting in inflammation, tissue damage, and subsequent tissue remodelling and organ fibrosis. In contrast to acute inflammatory reactions, pathogenic fibrosis typically results from the chronic inflammatory reactions characterizing autoimmune diseases. Despite having obvious aetiological and clinical outcome distinctions, most chronic autoimmune fibrotic disorders have in common a persistent and sustained production of growth factors, proteolytic enzymes, angiogenic factors, and fibrogenic cytokines, which together stimulate the deposition of connective tissue elements or epithelial to mesenchymal transformation (EMT) that progressively remodels and destroys normal tissue architecture leading to organ failure. Despite its enormous impact on human health, there are currently no approved treatments that directly target the molecular mechanisms of fibrosis. The primary goal of this review is to discuss the most recent identified mechanisms of chronic autoimmune diseases characterized by a fibrotic evolution with the aim to identify possible common and unique mechanisms of fibrogenesis that might be exploited in the development of effective antifibrotic therapies.

Targeting PPARs for therapy of atherosclerosis: A review

Atherosclerosis, a chief pathogenic factor of cardiovascular disease, is associated with many factors including inflammation, dyslipidemia, and oxidative stress. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors and are widely expressed with tissue- and cell-specificity. They control multiple genes that are involved in lipid metabolism, inflammatory response, and redox homeostasis. Given the diverse biological functions of PPARs, they have been extensively studied since their discovery in 1990s. Although controversies exist, accumulating evidence have demonstrated that PPAR activation attenuates atherosclerosis. Recent advances are valuable for understanding the mechanisms of action of PPAR activation. This article reviews the recent findings, mainly from the year of 2018 to present, including endogenous molecules in regulation of PPARs, roles of PPARs in atherosclerosis by focusing on lipid metabolism, inflammation, and oxidative stress, and synthesized PPAR modulators. This article provides information valuable for researchers in the field of basic cardiovascular research, for pharmacologists that are interested in developing novel PPAR agonists and antagonists with lower side effects as well as for clinicians.

The role of peroxisome proliferator-activated receptors in the tumor microenvironment, tumor cell metabolism, and anticancer therapy

Peroxisome proliferator-activated receptors (PPARs) have been extensively studied for over 3 decades and consist of three isotypes, including PPARα, γ, and β/δ, that were originally considered key metabolic regulators controlling energy homeostasis in the body. Cancer has become a leading cause of human mortality worldwide, and the role of peroxisome proliferator-activated receptors in cancer is increasingly being investigated, especially the deep molecular mechanisms and effective cancer therapies. Peroxisome proliferator-activated receptors are an important class of lipid sensors and are involved in the regulation of multiple metabolic pathways and cell fate. They can regulate cancer progression in different tissues by activating endogenous or synthetic compounds. This review emphasizes the significance and knowledge of peroxisome proliferator-activated receptors in the tumor microenvironment, tumor cell metabolism, and anti-cancer treatment by summarizing recent research on peroxisome proliferator-activated receptors. In general, peroxisome proliferator-activated receptors either promote or suppress cancer in different types of tumor microenvironments. The emergence of this difference depends on various factors, including peroxisome proliferator-activated receptor type, cancer type, and tumor stage. Simultaneously, the effect of anti-cancer therapy based on drug-targeted PPARs differs or even opposes among the three peroxisome proliferator-activated receptor homotypes and different cancer types. Therefore, the current status and challenges of the use of peroxisome proliferator-activated receptors agonists and antagonists in cancer treatment are further explored in this review.

Effect of PPARγ on oxidative stress in diabetes-related dry eye

Oxidative stress is closely associated with diabetes and can cause free radical accumulation and eventually lead to ocular surface tissue damage. The purpose of this study was to investigate peroxisome proliferator-activated receptor-γ (PPARγ) expression in the lacrimal gland (LG), meibomian gland, and cornea of diabetes-related dry eye mice and whether the PPARγ agonist rosiglitazone can alleviate the oxidative stress of the ocular surface, thereby improving the condition of diabetes-related dry eye. Quantitative RT-PCR (Q-PCR) showed that the PPARγ, catalase, glutathione peroxidase 3, and heme oxygenase-1 (HO-1) mRNA expression levels in the LG of diabetes-related dry eye mice decreased at 8 and 12 weeks. In addition, the increased levels of oxidative stress were confirmed by western blot. Although the mRNA expression levels of antioxidant enzymes in the cornea and meibomian gland decreased at 8 weeks, some of them recovered by 12 weeks. Rosiglitazone alleviated ocular surface damage and increased corneal sensitivity and tear production in diabetes-related dry eye mice. Moreover, the reactive oxygen species accumulation was reduced and the PPARγ, HO-1, and glutathione peroxidase 3 mRNA expression levels were increased in the LG. The PPARγ, HO-1, translocase of the outer membrane 20, and mitochondrial transcription factor A protein levels were also significantly increased. These results demonstrated that rosiglitazone reduced oxidative stress in the LG of diabetes-related dry eye mice, at least in part, by activating PPARγ to up-regulate antioxidant enzyme expression.

Cyclophilin A accelerates SiO2-induced macrophage foaming

Silicosis is a common occupational disease characterized by lung inflammation, fibrosis and pulmonary dysfunction caused by long-term inhalation of free SiO₂. Cell foaming and the change of CyPA have been observed in SiO₂-induced macrophages, but the specific mechanism of CyPA in SiO₂-induced foam cells remains poorly understood. The purpose of this study is to explore the mechanism of CyPA in SiO₂-induced macrophage foaming and its effect on silicosis. We found that overexpression of CyPA promoted the macrophage foaming and the expression of COL I and α-SMA, while silencing CyPA inhibites the macrophage foaming and the expression of COL I and α-SMA. After blocking the expression of CD36 on the basis of overexpression CyPA, we found it inhibites the macrophage foaming. In conclusion, CyPA can affect the foaming of macrophages and may participate in silicosis fibrosis.

Peroxisome Proliferator-Activated Receptor-Targeted Therapies: Challenges upon Infectious Diseases

Peroxisome proliferator-activated receptors (PPARs) α, β, and γ are nuclear receptors that orchestrate the transcriptional regulation of genes involved in a variety of biological responses, such as energy metabolism and homeostasis, regulation of inflammation, cellular development, and differentiation. The many roles played by the PPAR signaling pathways indicate that PPARs may be useful targets for various human diseases, including metabolic and inflammatory conditions and tumors. Accumulating evidence suggests that each PPAR plays prominent but different roles in viral, bacterial, and parasitic infectious disease development. In this review, we discuss recent PPAR research works that are focused on how PPARs control various infections and immune responses. In addition, we describe the current and potential therapeutic uses of PPAR agonists/antagonists in the context of infectious diseases. A more comprehensive understanding of the roles played by PPARs in terms of host-pathogen interactions will yield potential adjunctive personalized therapies employing PPAR-modulating agents.

Cinnamon: an aromatic condiment applicable to chronic kidney disease

Cinnamon, a member of the Lauraceae family, has been widely used as a spice and traditional herbal medicine for centuries and has shown beneficial effects in cardiovascular disease, obesity, and diabetes. However, its effectiveness as a therapeutic intervention for chronic kidney disease (CKD) remains unproven. The bioactive compounds within cinnamon, such as cinnamaldehyde, cinnamic acid, and cinnamate, can mitigate oxidative stress, inflammation, hyperglycemia, gut dysbiosis, and dyslipidemia, which are common complications in patients with CKD. In this narrative review, we assess the mechanisms by which cinnamon may alleviate complications observed in CKD and the possible role of this spice as an additional nutritional strategy for this patient group.

Omega-3 polyunsaturated fatty acids alleviate early brain injury after traumatic brain injury by inhibiting neuroinflammation and necroptosis

Presently, traumatic brain injury (TBI) is a leading contributor to disability and mortality that places a considerable financial burden on countries all over the world. Docosahexaenoic acid and eicosapentaenoic acid are two kinds of omega-3 polyunsaturated fatty acids (ω-3 PUFA), both of which have been shown to have beneficial biologically active anti-inflammatory and antioxidant effects. However, the neuroprotective effect of ω-3 PUFA in TBI has not been proven, and its probable mechanism remains obscure. We suppose that ω-3 PUFA can alleviate early brain injury (EBI) via regulating necroptosis and neuroinflammation after TBI. This research intended to examine the neuroprotective effect of ω-3 and its possible molecular pathways in a C57BL/6 mice model of EBI caused by TBI. Cognitive function was assessed by measuring the neuronal necroptosis, neuroinflammatory cytokine levels, brain water content, and neurological score. The findings demonstrate that administration of ω-3 remarkably elevated neurological scores, alleviated cerebral edema, and reduced inflammatory cytokine levels of NF-κB, interleukin-1β (IL-1β), IL-6, and TNF-α, illustrating that ω-3 PUFA attenuated neuroinflammation, necroptosis, and neuronal cell death following TBI. The PPARγ/NF-κB signaling pathway is partially responsible for the neuroprotective activity of ω-3. Collectively, our findings illustrate that ω-3 can alleviate EBI after TBI against neuroinflammation and necroptosis.

Integrative proteomics and metabolomics approach to identify the key roles of icariin-mediated protective effects against cyclophosphamide-induced spermatogenesis dysfunction in mice

The alkylating antineoplastic agent cyclophosphamide (CP) is known to be toxic to the male reproductive system, but there are no effective prevention or treatment options. The flavonoid icariin (ICA), which is used in Chinese medicine, has been shown to have a number of biological functions, including testicular protection. The current study looked into the protective effects of ICA in preventing CP-induced spermatogenesis dysfunction. The current study looked into the role of ICA in preventing testicular dysfunction caused by CP. For 5 days, healthy adult mice were given saline or a single dose of CP (50 mg/kg) intraperitoneally (i.p). For the next 30 days, mice were given ICA (80 mg/kg) by gavage. Animals were euthanized 12 h after receiving ICA, and testes were removed for biochemical, histopathological, sperm evaluation, and transmission electron microscope analysis (TEM). We also investigated the potential biological effects of ICA on CP-induced spermatogenesis dysfunction in mice using an integrated proteomic and metabolomic approach. The levels of 8309 proteins and 600 metabolites were measured. The majority of the differential proteins and metabolites were found to be enriched in a variety of metabolic pathways, including the PI3K-Akt signaling pathway, necroptosis, the mTOR signaling pathway, glycerophospholipid metabolism, and ABC transporters, implying that ICA may have molecular mechanisms that contribute to CP-induced spermatogenesis dysfunction in the testis. Taken together, these findings show that ICA effectively reduces testis injury, implying that ICA may have a role in male infertility preservation.

Current strategies for targeted therapy of liver fibrosis

Liver fibrosis (LF) is an unfavorable event in the natural course of chronic liver diseases (CLD), therefore, early implementation and widespread use of antifibrotic therapy methods is a pressing issue in hepatology. The aim of the review was to describe current approaches to targeted therapy of LF.

PubMed database, Google Scholar search engine, Cochrane Database of Systematic Reviews, eLIBRARY.RU scientific electronic library, as well as reference lists of articles were used to search for scientific articles. The publications that corresponded to the aim of the study were selected for the period from 1998 to 2021 by the terms “liver fibrosis”, “pathogenesis”, and “treatment”. Inclusion criteria were restricted to targeted therapy of LF.

Despite the growing evidence for reversibility of LF, there are currently no effective or clinically approved regimens for its specific therapy. However, taking into account the relevance of the issue, scientific research in this area is necessary. Multiple drugs with a good safety profile have been studied, which, though intended for other purposes, can have a positive effect on LF. In addition, a number of innovative approaches that differ from pharmacotherapy inspire optimism about finding a solution to this problem. It is obvious that studies focused on well-characterized groups of patients with confirmed histologic, elastography, clinical, and radiological parameters are required. This is a challenging task, since the key point will be stratification of risk based on ethnicity, etiology, and clinical status, and very large samples will be required for a reliable assessment. Nevertheless, the solution will increase efficiency of treatment for patients with CLD, improve their prognosis and quality of life, and significantly reduce the need for liver transplantation, a demand for which remains extremely high worldwide.

Effects of Cigarette Smoke Exposure on the Gut Microbiota and Liver Transcriptome in Mice Reveal Gut–Liver Interactions

Cigarette smoke exposure has a harmful impact on health and increases the risk of disease. However, studies on cigarette-smoke-induced adverse effects from the perspective of the gut–liver axis are lacking. In this study, we evaluated the adverse effects of cigarette smoke exposure on mice through physiological, biochemical, and histopathological analyses and explored cigarette-smoke-induced gut microbiota imbalance and changes in liver gene expression through a multiomics analysis. We demonstrated that cigarette smoke exposure caused abnormal physiological indices (including reduced body weight, blood lipids, and food intake) in mice, which also triggered liver injury and induced disorders of the gut microbiota and liver transcriptome (especially lipid metabolism). A significant correlation between intestinal bacterial abundance and the expression of lipid-metabolism-related genes was detected, suggesting the coordinated regulation of lipid metabolism by gut microbiota and liver metabolism. Specifically, Salmonella (harmful bacterium) was negatively and positively correlated with up- (such as Acsl3 and Me1) and downregulated genes (such as Angptl4, Cyp4a12a, and Plin5) involved in lipid metabolism, while Ligilactobacillus (beneficial bacterium) showed opposite trends with these genes. Our results clarified the key role of gut microbiota in liver damage and metabolism and improved the understanding of gut–liver interactions caused by cigarette smoke exposure.

Peroxisome Proliferator-Activated Receptors Regulate Hepatic Immunity and Assist in the Treatment of Primary Biliary Cholangitis

Fibrates, which are agonists of peroxisome proliferator-activated receptor alpha, have received increasing attention in the treatment of primary biliary cholangitis. Reduced alkaline phosphatase levels and improved clinical outcomes were observed in patients with primary biliary cholangitis with an inadequate response to ursodeoxycholic acid (UDCA) monotherapy4 when treated with bezafibrate or fenofibrate combined with UDCA. In contrast to obeticholic acid, which exacerbates pruritus in patients, fibrates have been shown to relieve pruritus. Clinical trial outcomes show potential for the treatment of primary biliary cholangitis by targeting peroxisome proliferator-activated receptors. It is currently agreed that primary biliary cholangitis is an autoimmune-mediated cholestatic liver disease, and peroxisome proliferator-activated receptor is a nuclear receptor that regulates the functions of multiple immune cells, thus playing an important role in regulating innate and adaptive immunity. Therefore, this review focuses on the immune disorder of primary biliary cholangitis and summarizes the regulation of hepatic immunity when peroxisome proliferator-activated receptors are targeted for treating primary biliary cholangitis.

Liver Protective Effect of Fenofibrate in NASH/NAFLD Animal Models

Nonalcoholic fatty liver disease (NAFLD) is initiated by excessive fat buildup in the liver, affecting around 35% of the world population. Various circumstances contribute to the initiation and progression of NAFLD, and it encompasses a wide range of disorders, from simple steatosis to nonalcoholic steatohepatitis (NASH), cirrhosis, and liver cancer. Although several treatments have been proposed, there is no definitive cure for NAFLD. In recent decades, several medications related to other metabolic disorders have been evaluated in preclinical studies and in clinical trials due to the correlation of NAFLD with other metabolic diseases. Fenofibrate is a fibrate drug approved for dyslipidemia that could be used for modulation of hepatic fat accumulation, targeting peroxisome proliferator-activator receptors, and de novo lipogenesis. This drug offers potential therapeutic efficacy for NAFLD due to its capacity to decrease the accumulation of hepatic lipids, as well as its antioxidant, anti-inflammatory, and antifibrotic properties. To better elucidate the pathophysiological processes underlying NAFLD, as well as to test therapeutic agents/interventions, experimental animal models have been extensively used. In this article, we first reviewed experimental animal models that have been used to evaluate the protective effects of fenofibrate on NAFLD/NASH. Next, we investigated the impact of fenofibrate on the hepatic microcirculation in NAFLD and then summarized the beneficial effects of fenofibrate, as compared to other drugs, for the treatment of NAFLD. Lastly, we discuss possible adverse side effects of fenofibrate on the liver.

PPARα Signaling: A Candidate Target in Psychiatric Disorder Management

Peroxisome proliferator-activator receptors (PPARs) regulate lipid and glucose metabolism, control inflammatory processes, and modulate several brain functions. Three PPAR isoforms have been identified, PPARα, PPARβ/δ, and PPARγ, which are expressed in different tissues and cell types. Hereinafter, we focus on PPARα involvement in the pathophysiology of neuropsychiatric and neurodegenerative disorders, which is underscored by PPARα localization in neuronal circuits involved in emotion modulation and stress response, and its role in neurodevelopment and neuroinflammation. A multiplicity of downstream pathways modulated by PPARα activation, including glutamatergic neurotransmission, upregulation of brain-derived neurotrophic factor, and neurosteroidogenic effects, encompass mechanisms underlying behavioral regulation. Modulation of dopamine neuronal firing in the ventral tegmental area likely contributes to PPARα effects in depression, anhedonia, and autism spectrum disorder (ASD). Based on robust preclinical evidence and the initial results of clinical studies, future clinical trials should assess the efficacy of PPARα agonists in the treatment of mood and neurodevelopmental disorders, such as depression, schizophrenia, and ASD.

Impact of fenofibrate on NAFLD/NASH: A genetic perspective

Nonalcoholic fatty liver disease (NAFLD), caused by an accumulation of fat deposits in hepatocytes, prevalently affects at least one-third of the world's population. The progression of this disorder can potentially include a spectrum of consecutive stages, specifically: steatosis, steatohepatitis and cirrhosis. Fenofibrate exhibits potential therapeutic efficacy for NAFLD owing to several properties, which include antioxidant, apoptotic, anti-inflammatory and antifibrotic activity. In the present review, we discuss the direct or indirect impact of fenofibrate on genes involved at various stages in the progression of NAFLD. Moreover, we have reviewed studies that compare fenofibrate with other drugs in treating NAFLD, as well as recent clinical trials, in an attempt to identify reliable scientific and clinical evidence concerning the therapeutic effects and benefits of fenofibrate on NAFLD. Teaser.

Peroxisome proliferator-activated receptor-γ ameliorates neuronal ferroptosis after traumatic brain injury in mice by inhibiting cyclooxygenase-2

Among the multiple kinds of neuronal cell death triggered by traumatic brain injury (TBI), ferroptosis, an iron-dependent lipid peroxidative regulatory cell death, has a critical role. Peroxisome proliferator-activated receptor-γ (PPARγ) is a nuclear transcription factor that regulates lipid metabolism and suppresses neuronal inflammation. However, the role of PPARγ in neuronal ferroptosis induced by TBI remains unclear. Here, we investigated the regulatory effect of PPARγ on neuronal ferroptosis in a weight-drop TBI model in vivo and an RAS-selective lethal 3 (RSL3)-activated ferroptotic neuronal model in vitro. PPARγ was mainly localized in the nucleus of neurons and was decreased in both the in vivo TBI model and the in vitro ferroptotic neuronal model. The addition of a specific agonist, pioglitazone, activated PPARγ, which protected neuronal function post-TBI in vivo and increased the viability of ferroptotic neurons in vitro. Further investigation suggested that PPARγ probably attenuates neuronal ferroptosis by downregulating cyclooxygenase-2 (COX2) protein expression levels in vivo and in vitro. This study revealed the relationship among PPARγ, ferroptosis and TBI and identified a potential target for comprehensive TBI treatment.

The Role of Peroxisome Proliferator-Activated Receptors in Kidney Diseases

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of ligand-activated transcription factors. Accumulating evidence suggests that PPARs may play an important role in the pathogenesis of kidney disease. All three members of the PPAR subfamily, PPARα, PPARβ/δ, and PPARγ, have been implicated in many renal pathophysiological conditions, including acute kidney injury, diabetic nephropathy, and chronic kidney disease, among others. Emerging data suggest that PPARs may be potential therapeutic targets for renal disease. This article reviews the physiological roles of PPARs in the kidney and discusses the therapeutic utility of PPAR agonists in the treatment of kidney disease.

Obstructive Sleep Apnea Affects Lacrimal Gland Function

Purpose

To determine the effect of obstructive sleep apnea syndrome (OSA) on lacrimal gland function and its mechanism.

Methods

Male mice aged seven to eight weeks were housed in cages with cyclic intermittent hypoxia to mimic OSA, and the control group was kept in a normal environment. Slit-lamp observation, fluorescein staining, and corneal sensitivity detection are used to assess cornea changes. Tear secretion was detected by phenol red cotton thread, and the pathological changes of lacrimal gland were observed by hematoxylin and eosin staining, oil red O staining, cholesterol and triglyceride kits, immunofluorescence staining, immunohistochemical staining, real-time polymerase chain reaction, transmission electron microscopy, and Western blot.

Results

Studies revealed a decreased tear secretion, corneal epithelial defects and corneal hypersensitivity. Myoepithelial cell damage, abnormal lipid accumulation, reduced cell proliferation, increased apoptosis and inflammatory cell infiltration in the lacrimal gland were also seen. Hifα and NF-κB signaling pathways, moreover, were activated, while Pparα was downregulated, in the lacrimal glands of OSA mice. Fenofibrate treatment significantly alleviated pathological changes of the lacrimal gland induced by OSA.

Conclusion

OSA disturbs the Hifα/Pparα/NF-κB signaling axis, which affects lacrimal gland structure and function and induces dry eye.

Potential Therapeutic Effects of PPAR Ligands in Glioblastoma

Glioblastoma (GB), also known as grade IV astrocytoma, represents the most aggressive form of brain tumor, characterized by extraordinary heterogeneity and high invasiveness and mortality. Thus, a great deal of interest is currently being directed to investigate a new therapeutic strategy and in recent years, the research has focused its attention on the evaluation of the anticancer effects of some drugs already in use for other diseases. This is the case of peroxisome proliferator-activated receptors (PPARs) ligands, which over the years have been revealed to possess anticancer properties. PPARs belong to the nuclear receptor superfamily and are divided into three main subtypes: PPAR-α, PPAR-β/δ, and PPAR-γ. These receptors, once activated by specific natural or synthetic ligands, translocate to the nucleus and dimerize with the retinoid X receptors (RXR), starting the signal transduction of numerous genes involved in many physiological processes. PPARs receptors are activated by specific ligands and participate principally in the preservation of homeostasis and in lipid and glucose metabolism. In fact, synthetic PPAR-α agonists, such as fibrates, are drugs currently in use for the clinical treatment of hypertriglyceridemia, while PPAR-γ agonists, including thiazolidinediones (TZDs), are known as insulin-sensitizing drugs. In this review, we will analyze the role of PPARs receptors in the progression of tumorigenesis and the action of PPARs agonists in promoting, or not, the induction of cell death in GB cells, highlighting the conflicting opinions present in the literature.

Discovery of new and highly effective quadruple FFA1 and PPARα/γ/δ agonists as potential anti-fatty liver agents

Non-alcoholic fatty liver disease (NAFLD) has become the most common hepatic disease, while no drug was approved until now. The previous study reported that the quadruple FFA1/PPAR-α/γ/δ agonist RLA8 provided better efficacy than obeticholic acid on NASH. In the present study, two design strategies were introduced to explore better quadruple FFA1/PPAR-α/γ/δ agonists with improved metabolic stability. These efforts ultimately resulted in the identification of ZLY18, a quadruple FFA1/PPAR-α/γ/δ agonist with twice higher metabolic half-life than RLA8 in the liver microsome. In the triton-1339W-induced hyperlipidemic model, ZLY18 reversed hyperlipidemia to an almost normal level, which exhibited far stronger lipid-lowering effects than that of RLA8. Moreover, ZLY18 significantly decreased steatosis, hepatocellular ballooning, inflammation and liver fibrosis in NASH model even better than RLA8. Further mechanism studies suggested that ZLY18 exerts stronger effects than RLA8 on the regulation of the gene related to lipid synthesis, oxidative stress, inflammation and fibrosis. In addition, ZLY18 is more effective than pirfenidone in the prevention of CCl4-induced liver fibrosis. Besides, ZLY18 has an acceptable safety profile in the acute toxicity study at a high dose of 500 mg/kg. Therefore, ZLY18 represents a novel and highly promising quadruple FFA1/PPAR-α/γ/δ agonist worth of further investigation and development.

Target Deconvolution of Fenofibrate in Nonalcoholic Fatty Liver Disease Using Bioinformatics Analysis

Background

Nonalcoholic fatty liver disease (NAFLD) is a prevalent form of liver damage, affecting ~25% of the global population. NAFLD comprises a spectrum of liver pathologies, from hepatic steatosis to nonalcoholic steatohepatitis (NASH), and may progress to liver fibrosis and cirrhosis. The presence of NAFLD correlates with metabolic disorders such as hyperlipidemia, obesity, blood hypertension, cardiovascular, and insulin resistance. Fenofibrate is an agonist drug for peroxisome proliferator-activated receptor alpha (PPARα), used principally for treatment of hyperlipidemia. However, fenofibrate has recently been investigated in clinical trials for treatment of other metabolic disorders such as diabetes, cardiovascular disease, and NAFLD. The evidence to date indicates that fenofibrate could improve NAFLD. While PPARα is considered to be the main target of fenofibrate, fenofibrate may exert its effect through impact on other genes and pathways thereby alleviating, and possibly reversing, NAFLD. In this study, using bioinformatics tools and gene-drug, gene-diseases databases, we sought to explore possible targets, interactions, and pathways involved in fenofibrate and NAFLD.

Methods

We first determined significant protein interactions with fenofibrate in the STITCH database with high confidence (0.7). Next, we investigated the identified proteins on curated targets in two databases, including the DisGeNET and DISEASES databases, to determine their association with NAFLD. We finally constructed a Venn diagram for these two collections (curated genes-NAFLD and fenofibrate-STITCH) to uncover possible primary targets of fenofibrate. Then, Gene Ontology (GO) and KEGG were analyzed to detect the significantly involved targets in molecular function, biological process, cellular component, and biological pathways. A P value < 0.01 was considered the cut-off criterion. We also estimated the specificity of targets with NAFLD by investigating them in disease-gene associations (STRING) and EnrichR (DisGeNET). Finally, we verified our findings in the scientific literature.

Results

We constructed two collections, one with 80 protein-drug interactions and the other with 95 genes associated with NAFLD. Using the Venn diagram, we identified 11 significant targets including LEP, SIRT1, ADIPOQ, PPARA, SREBF1, LDLR, GSTP1, VLDLR, SCARB1, MMP1, and APOC3 and then evaluated their biological pathways. Based on Gene Ontology, most of the targets are involved in lipid metabolism, and KEGG enrichment pathways showed the PPAR signaling pathway, AMPK signaling pathway, and NAFLD as the most significant pathways. The interrogation of those targets on authentic disease databases showed they were more specific to both steatosis and steatohepatitis liver injury than to any other diseases in these databases. Finally, we identified three significant genes, APOC3, PPARA, and SREBF1, that showed robust drug interaction with fenofibrate.

Conclusion

Fenofibrate may exert its effect directly or indirectly, via modulation of several key targets and pathways, in the treatment of NAFLD.

Docosahexaenoic acid reduces hypoglycemia-induced neuronal necroptosis via the peroxisome proliferator-activated receptor γ/nuclear factor-κB pathway

DHA has been shown to be neuroprotective and important to neurogenesis, but its role in HG-induced brain injury and the underlying mechanisms remain unknown. To elucidate the therapeutic effect of DHA, we established a mouse model with insulin-induced hypoglycemic brain injury and an in vitro model of HT-22 cells using a sugar-free medium. DHA treatment significantly reduced neuronal death and improved HG-induced learning and memory deficits. Moreover, DHA inhibited neuronal necroptosis and decreased the concentrations of TNF-α, IL-1β and TNFR1. DHA also activated PPAR-γ and suppressed the NF-κB pathway in mouse brain tissues. In vitro, DHA treatment restored the viability and decreased necroptosis of HT-22 cells treated with glucose deprivation. However, the inhibition of PPAR-γ with T0070907 reversed neuroprotective and anti-necroptosis effects of DHA in HG-induced brain injury, which is associated with the activation of the downstream NF-κB pathway. We conclude that DHA displays a protective effect against HG-induced brain injury through the PPAR-γ/NF-κB pathway and represents a promising method to prevent HG-induced brain injury.

Discovery of the first-in-class dual PPARδ/γ partial agonist for the treatment of metabolic syndrome

The peroxisome proliferator-activated receptors (PPARs) exert vital function in the regulation of energy metabolism, which were considered as promising targets of metabolic syndrome. Until now, PPARδ/γ dual agonist is rarely reported, and thereby the pharmacologic action of PPARδ/γ dual agonist is still unclear. In this study, we identified a dual PPARδ/γ partial agonist 6 (ZLY06) based on the cyclization strategy of PPARα/δ dual agonist GFT505. ZLY06 revealed excellent pharmacokinetic profiles suitable for oral medication. Moreover, ZLY06 markedly improved glucolipid metabolism without weight gain, and alleviated fatty liver by promoting the β-oxidation of fatty acid and inhibiting hepatic lipogenesis. In contrast, weight gain and hepatic steatosis were observed in Rosiglitazone, a widely used PPARγ full agonist. All of these results indicated that ZLY06 exhibits potential benefits on metabolic syndrome, while no adverse effects related to PPARγ full agonist.

Human skeletal muscle CD90+ fibro-adipogenic progenitors are associated with muscle degeneration in type 2 diabetic patients

Type 2 diabetes mellitus (T2DM) is associated with impaired skeletal muscle function and degeneration of the skeletal muscles. However, the mechanisms underlying the degeneration are not well described in human skeletal muscle. Here we show that skeletal muscle of T2DM patients exhibit degenerative remodeling of the extracellular matrix that is associated with a selective increase of a subpopulation of fibro-adipogenic progenitors (FAPs) marked by expression of THY1 (CD90)-the FAP^CD90+. We identify platelet-derived growth factor (PDGF) as a key FAP regulator, as it promotes proliferation and collagen production at the expense of adipogenesis. FAPs^CD90+ display a PDGF-mimetic phenotype, with high proliferative activity, clonogenicity, and production of extracellular matrix. FAP^CD90+ proliferation was reduced by in vitro treatment with metformin. Furthermore, metformin treatment reduced FAP content in T2DM patients. These data identify a PDGF-driven conversion of a subpopulation of FAPs as a key event in the fibrosis development in T2DM muscle.

Foresight regarding drug candidates acting on the succinate-GPR91 signalling pathway for non-alcoholic steatohepatitis (NASH) treatment

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, and it is a liver manifestation of metabolic syndrome, with a histological spectrum from simple steatosis to non-alcoholic steatohepatitis (NASH). NASH can evolve into progressive liver fibrosis and eventually lead to liver cirrhosis. The pathological mechanism of NASH is multifactorial, involving a series of metabolic disorders and changes that trigger low-level inflammation in the liver and other organs. In the pathogenesis of NASH, the signal transduction pathway involving succinate and the succinate receptor (G-protein-coupled receptor 91, GPR91) regulates inflammatory cell activation and liver fibrosis. This review describes the mechanism of the succinate-GPR91 signalling pathway in NASH and summarizes the drugs that act on this pathway, with the aim of providing a new approach to NASH treatment.

Atorvastatin Ester Regulates Lipid Metabolism in Hyperlipidemia Rats via the PPAR-signaling Pathway and HMGCR Expression in the Liver

Atorvastatin ester (Ate) is a structural trim of atorvastatin that can regulate hyperlipidemia. The purpose of this study was to evaluate the lipid-lowering effect of Ate. Male Sprague Dawley (SD) rats were fed a high-fat diet for seven months and used as a hyperlipidemia model. The lipid level and liver function of the hyperlipidemia rats were studied by the levels of TG, TC, LDL, HDL, ALT, and AST in serum after intragastric administration with different doses of Ate. HE staining was used to observe the pathological changes of the rat liver and gastrocnemius muscle. The lipid deposits in the liver of rats were observed by staining with ORO. The genes in the rat liver were sequenced by RNA-sequencing. The results of the RNA-sequencing were further examined by qRT-PCR and western blotting. Biochemical test results indicated that Ate could obviously improve the metabolic disorder and reduce both the ALT and AST levels in serum of the hyperlipidemia rats. Pathological results showed that Ate could improve HFD-induced lipid deposition and had no muscle toxicity. The RNA-sequencing results suggested that Ate affected liver lipid metabolism and cholesterol, metabolism in the hyperlipidemia-model rats may vary via the PPAR-signaling pathway. The western blotting and qRT-PCR results demonstrated the Ate-regulated lipid metabolism in the hyperlipidemia model through the PPAR-signaling pathway and HMGCR expression. In brief, Ate can significantly regulate the blood lipid level of the model rats, which may be achieved by regulating the PPAR-signaling pathway and HMGCR gene expression.

Hispidulin inhibits proliferation, migration, and invasion by promoting autophagy via regulation of PPARγ activation in prostate cancer cells and xenograft models

Prostate cancer (PCa) is one of the important factors of cancer deaths especially in the western countries. Hispidulin (4',5,7-trihydroxy-6-methoxyflavone) is a phenolic flavonoid compound proved to possess anticancer properties, but its effects on PCa are left to be released. The aims of this study were to investigate the effects and the relative mechanisms of Hispidulin on PCa development. Hispidulin administration inhibited proliferation, invasion, and migration, while accelerated apoptosis in Du145 and VCaP cells, which was accompanied by PPARγ activation and autophagy enhancement. The beneficial effects of Hispidulin could be diminished by PPARγ inhibition. Besides, Hispidulin administration suppressed PCa tumorigenicity in Xenograft models, indicating the anticancer properties in vivo. Therefore, our work revealed that the anticancer properties of Hispidulin might be conferred by its activation on PPARγ and autophagy.

Post-Treatment with Amorfrutin B Evokes PPARγ-Mediated Neuroprotection against Hypoxia and Ischemia

In this study, we demonstrate for the first time that amorfrutin B, a selective modulator of peroxisome proliferator-activated receptor gamma—PPARγ, can protect brain neurons from hypoxia- and ischemia-induced degeneration when applied at 6 h post-treatment in primary cultures. The neuroprotective effect of amorfrutin B suggests that it promotes mitochondrial integrity and is capable of inhibiting reactive oxygen species—ROS activity and ROS-mediated DNA damage. PPARγ antagonist and Pparg mRNA silencing abolished the neuroprotective effect of amorfrutin B, which points to agonistic action of the compound on the respective receptor. Interestingly, amorfrutin B stimulated the methylation of the Pparg gene, both during hypoxia and ischemia. Amorfrutin B also increased the protein level of PPARγ during hypoxia but decreased the mRNA and protein levels of PPARγ during ischemia. Under ischemic conditions, amorfrutin B-evoked hypermethylation of the Pparg gene is in line with the decrease in the mRNA and protein expression of PPARγ. However, under hypoxic conditions, amorfrutin B-dependent hypermethylation of the Pparg gene does not explain the amorfrutin B-dependent increase in receptor protein expression, which suggests other regulatory mechanisms. Other epigenetic parameters, such as HAT and/or sirtuins activities, were affected by amorfrutin B under hypoxic and ischemic conditions. These properties position the compound among the most promising anti-stroke and wide-window therapeutics.