Peroxisome proliferator-activated receptor alpha-mediated drug toxicity in the liver

A comparative study of the hypolipidemic effects and mechanisms of action of Laminaria japonica- and Ascophyllum nodosum-derived fucoidans in apolipoprotein E-deficient mice

The structural characteristics of fucoidans exhibit species and regional diversity. Previous studies have demonstrated that Laminaria japonica- and Ascophyllum nodosum-derived fucoidans have type I and type II fucosyl chains, respectively. These chemical differences may contribute to distinct hypolipidemic effects and mechanisms of action. Chemical analysis demonstrated that the percentage contents of sulfate, glucuronic acid, and galactose were higher in L. japonica-derived fucoidans than those of A. nodosum-derived fucoidans. In hyperlipidemic apolipoprotein E-deficient mice, both A. nodosum- and L. japonica-derived fucoidans significantly decreased the plasma and hepatic levels of total cholesterol and triglyceride, leading to the reduction of atherosclerotic plaques. Western blotting experiments demonstrated that these fucoidans significantly enhanced the expression and levels of scavenger receptor B type 1, cholesterol 7 alpha-hydroxylase A1, and peroxisome proliferator-activated receptor (PPAR)-α, contributing to circulating lipoprotein clearance and fatty acid degradation, respectively. Differentially, L. japonica-derived fucoidan significantly increased the LXR/ATP-binding cassette G8 signaling pathway in the small intestine, as revealed by real-time quantitative PCR, which may lead to further cholesterol and other lipid excretion. Collectively, these data are useful for understanding the hypolipidemic mechanisms of action of seaweed-derived fucoidans, and their potential application for the prevention and/or treatment of atherosclerotic cardiovascular diseases.

PPAR agonists for the treatment of neuroinflammatory diseases

Peroxisome proliferator-activated receptors [PPARs; PPARα, PPARβ/δ (also known as PPARδ), and PPARγ] widely recognized for their important role in glucose/lipid homeostasis, have recently received significant attention due to their additional anti-inflammatory and neuroprotective effects. Several newly developed PPAR agonists have shown high selectivity for specific PPAR isoforms in vitro and in vivo, offering the potential to achieve desired therapeutic outcomes while reducing the risk of adverse effects. In this review, we discuss the latest preclinical and clinical studies of the activation of PPARs by synthetic, natural, and isoform-specific (full, partial, and dual) agonists for the treatment of neuroinflammatory diseases, including HIV-associated neurocognitive disorders (HAND), Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), and cerebral ischemia.

Molecular dynamics articulated multilevel virtual screening protocol to discover novel dual PPAR α/γ agonists for anti-diabetic and metabolic applications

PPARα and PPARγ are isoforms of the nuclear receptor superfamily which regulate glucose and lipid metabolism. Activation of PPARα and PPARγ receptors by exogenous ligands could transactivate the expression of PPARα and PPARγ-dependent genes, and thereby, metabolic pathways get triggered, which are helpful to ameliorate treatment for the type 2 diabetes mellitus, and related metabolic complications. Herein, by understanding the structural requirements for ligands to activate PPARα and PPARγ proteins, we developed a multilevel in silico-based virtual screening protocol to identify novel chemical scaffolds and further design and synthesize two distinct series of glitazone derivatives with advantages over the classical PPARα and PPARγ agonists. Moreover, the synthesized compounds were biologically evaluated for PPARα and PPARγ transactivation potency from nuclear extracts of 3T3-L1 cell. Furthermore, glucose uptake assay on L6 cells confirmed the potency of the synthesized compounds toward glucose regulation. Percentage lipid-lowering potency was also assessed through triglyceride estimate from 3T3-L1 cell extracts. Results suggested the ligand binding mode was in orthosteric fashion as similar to classical agonists. Thus molecular docking and molecular dynamics (MD) simulation experiments were executed to validate our hypothesis on mode of ligands binding and protein complex stability. Altogether, the present study developed a newer protocol for virtual screening and enables to design of novel glitazones for activation of PPARα and PPARγ-mediated pathways. Accordingly, present approach will offer benefit as a therapeutic strategy against type 2 diabetes mellitus and associated metabolic complications.

Efficacy and safety of pemafibrate in patients with hypertriglyceridemia in clinical settings: A retrospective study

BACKGROUND AND AIMS

Recently, pemafibrate, a selective PPARα modulator, has been developed as a treatment for hypertriglyceridemia and has attracted much attention. The aims of this study were to evaluate the efficacy and safety of pemafibrate in hypertriglyceridemia patients under clinical settings.

METHODS AND RESULTS

We evaluated changes in lipid profiles and various parameters before and after 24-week pemafibrate administration in patients with hypertriglyceridemia who had not previously taken fibrate medications. There were 79 cases included in the analysis. 24 weeks after the treatment with pemafibrate, TG was significantly reduced from 312 ± 226 to 167 ± 94 mg/dL. In addition, lipoprotein fractionation tests using PAGE method showed a significant decrease in the ratio of VLDL and remnant fractionations, which are TG-rich lipoproteins. After pemafibrate administration, body weight, HbA1c, eGFR, and CK levels were not changed, but liver injury indices such as ALT, AST, and γ-GTP were significantly improved.

CONCLUSION

In this study, pemafibrate improved the metabolism of atherosclerosis-induced lipoproteins in hypertriglyceridemia patients. In addition, it showed no off-target effects such as hepatic and renal damage or rhabdomyolysis.

Contribution of adaptive immunity to human COPD and experimental models of emphysema

The pathophysiology of chronic obstructive pulmonary disease (COPD) and the undisputed role of innate immune cells in this condition have dominated the field in the basic research arena for many years. Recently, however, compelling data suggesting that adaptive immune cells may also contribute to the progressive nature of lung destruction associated with COPD in smokers have gained considerable attention. The histopathological changes in the lungs of smokers can be limited to the large or small airways, but alveolar loss leading to emphysema, which occurs in some individuals, remains its most significant and irreversible outcome. Critically, however, the question of why emphysema progresses in a subset of former smokers remained a mystery for many years. The recognition of activated and organized tertiary T- and B-lymphoid aggregates in emphysematous lungs provided the first clue that adaptive immune cells may play a crucial role in COPD pathophysiology. Based on these findings from human translational studies, experimental animal models of emphysema were used to determine the mechanisms through which smoke exposure initiates and orchestrates adaptive autoreactive inflammation in the lungs. These models have revealed that T helper (Th)1 and Th17 subsets promote a positive feedback loop that activates innate immune cells, confirming their role in emphysema pathogenesis. Results from genetic studies and immune-based discoveries have further provided strong evidence for autoimmunity induction in smokers with emphysema. These new findings offer a novel opportunity to explore the mechanisms underlying the inflammatory landscape in the COPD lung and offer insights for development of precision-based treatment to halt lung destruction.

Safety and efficacy of dyslipidemia treatment in NAFLD patients: a meta-analysis of randomized controlled trials

INTRODUCTION AND OBJECTIVES

Practicing physicians often hesitate to use statins and/or other lipid-lowering therapies in NAFLD due to concern for hepatotoxicity. The aim of this study is to examine the safety of lipid lowering therapies in NAFLD patients.

MATERIALS AND METHODS

Data from randomized control trials (RCT) among NAFLD patients were pooled to examine the effect of lipid-lowering therapies on liver chemistry, lipid profile, and liver histology. Results are reported as the mean difference of the change (pretreatment-posttreatment) between the treatment and control group.

RESULTS

A total of 21 placebo-controlled RCT on 1900 patients (304 receiving statins, 520 other lipid-lowering therapies, and 61 combinations) were treated for 26 weeks [Interquartile range (IQR): 17.5-52 weeks]. Pooled data showed an improved lipid profile without any worsening of ALT, AST, total bilirubin, or alkaline phosphatase at the end of the treatment period. NAFLD activity score improved with other lipid-lowering agents but not with statins. There was no change in individual components of NAFLD activity score or fibrosis stage.

CONCLUSION

This meta-analysis of randomized controlled trials examining statins and/or other lipid-lowering therapies in NAFLD patients showed no evidence of worsening liver chemistry. Studies with longer use of lipid-lowering therapies are suggested to examine the benefit of liver histology among patients with NAFLD.

PPARα: A potential therapeutic target of cholestasis

The accumulation of bile acids in the liver leads to the development of cholestasis and hepatocyte injury. Nuclear receptors control the synthesis and transport of bile acids in the liver. Among them, the farnesoid X receptor (FXR) is the most common receptor studied in treating cholestasis. The activation of this receptor can reduce the amount of bile acid synthesis and decrease the bile acid content in the liver, alleviating cholestasis. Ursodeoxycholic acid (UDCA) and obeticholic acid (OCA) have a FXR excitatory effect, but the unresponsiveness of some patients and the side effect of pruritus seriously affect the results of UDCA or OCA treatment. The activator of peroxisome proliferator-activated receptor alpha (PPARα) has emerged as a new target for controlling the synthesis and transport of bile acids during cholestasis. Moreover, the anti-inflammatory effect of PPARα can effectively reduce cholestatic liver injury, thereby improving patients’ physiological status. Here, we will focus on the function of PPARα and its involvement in the regulation of bile acid transport and metabolism. In addition, the anti-inflammatory effects of PPARα will be discussed in some detail. Finally, we will discuss the application of PPARα agonists for cholestatic liver disorders.

Mitochondrial Respiratory Complexes as Targets of Drugs: The PPAR Agonist Example

Mitochondrial bioenergetics are progressively acquiring significant pathophysiological roles. Specifically, mitochondria in general and Electron Respiratory Chain in particular are gaining importance as unintentional targets of different drugs. The so-called PPAR ligands are a class of drugs which not only link and activate Peroxisome Proliferator-Activated Receptors but also show a myriad of extrareceptorial activities as well. In particular, they were shown to inhibit NADH coenzyme Q reductase. However, the molecular picture of this intriguing bioenergetic derangement has not yet been well defined. Using high resolution respirometry, both in permeabilized and intact HepG2 cells, and a proteomic approach, the mitochondrial bioenergetic damage induced by various PPAR ligands was evaluated. Results show a derangement of mitochondrial oxidative metabolism more complex than one related to a simple perturbation of complex I. In fact, a partial inhibition of mitochondrial NADH oxidation seems to be associated not only with hampered ATP synthesis but also with a significant reduction in respiratory control ratio, spare respiratory capacity, coupling efficiency and, last but not least, serious oxidative stress and structural damage to mitochondria.

Antihypertriglyceridemia activities of naturally fermented green tea, Heukcha, extract through modulation of lipid metabolism in rats fed a high-fructose diet

Hypertriglyceridemia, a symptom of elevated triglyceride level in the blood, is a potent risk factor for cardiovascular and metabolic disorders. Among the numerous treatments to regulate circulating triglyceride levels, fibrates are widely used to treat hypertriglyceridemia, although they also have side effects such as hepatotoxicity and gallstone formation. In the present study, we aimed to investigate the blood triglyceride-lowering effects of a naturally fermented green tea extract (NFGT) and the underlying mechanisms on hypertriglyceridemia in vitro and in vivo models. NFGT suppressed the expression of lipogenic genes, while augmented expression of fatty acid oxidation-related genes in cultured cells, leading to the significant decrease of intracellular triglyceride content. NFGT treated group in fructose-induced hypertriglyceridemic rat model significantly decreased plasma and hepatic triglyceride, which was accompanied by an increase in excretion of fecal fat. Taken together, we propose that NFGT could be potentially a novel functional ingredient to prevent or treat hypertriglyceridemia.

Structural simplification and bioisostere principle lead to Bis-benzodioxole-fibrate derivatives as potential hypolipidemic and hepatoprotective agents

The bis-benzodioxole-fibrate hybrids were designed by structural simplification and bioisostere principle. Lipids lowering activity was preliminarily screened by Triton WR 1339 induced hyperlipidemia mice model, in which T3 showed the best hypolipidemia, decreasing plasma triglyceride (TG) and total cholesterol (TC), which were better than sesamin and fenofibrate (FF). T3 was also found to significantly reduce TG, TC and low density lipoprotein cholesterin (LDL-C) both in plasma and liver tissue of high fat diet (HFD) induced hyperlipidemic mice. In addition, T3 showed hepatoprotective activity, which the noteworthy amelioration in liver aminotransferases (AST and ALT) was evaluated and the histopathological observation exhibited that T3 inhibited lipids accumulation in the hepatic and alleviated liver damage. The expression of PPAR-α receptor involved lipids metabolism in liver tissue significantly increased after T3 supplementation. Other potent activity, such as antioxidation and anti-inflammation, was also observed. The molecular docking study revealed that T3 has good affinity activity toward to the active site of PPAR-α receptor. Based on these findings, T3 may serve as an effective hypolipidemic agent with hepatoprotection.

Influence of Genistein on Hepatic Lipid Metabolism in an In Vitro Model of Hepatic Steatosis

Nonalcoholic fatty liver disease (NAFLD) is among the leading causes of end-stage liver disease. The impaired hepatic lipid metabolism in NAFLD is exhibited by dysregulated PPARα and SREBP-1c signaling pathways, which are central transcription factors associated with lipid degradation and de novo lipogenesis. Despite the growing prevalence of this disease, current pharmacological treatment options are unsatisfactory. Genistein, a soy isoflavone, has beneficial effects on lipid metabolism and may be a candidate for NAFLD treatment. In an in vitro model of hepatic steatosis, primary human hepatocytes (PHHs) were incubated with free fatty acids (FFAs) and different doses of genistein. Lipid accumulation and the cytotoxic effects of FFAs and genistein treatment were evaluated by colorimetric and enzymatic assays. Changes in lipid homeostasis were examined by RT-qPCR and Western blot analyses. PPARα protein expression was induced in steatotic PHHs, accompanied by an increase in CPT1L and ACSL1 mRNA. Genistein treatment increased PPARα protein expression only in control PHHs, while CPTL1 and ACSL1 were unchanged and PPARα mRNA was reduced. In steatotic PHHs, genistein reversed the increase in activated SREBP-1c protein. The model realistically reflected the molecular changes in hepatic steatosis. Genistein suppressed the activation of SREBP-1c in steatotic hepatocytes, but the genistein-mediated effects on PPARα were abolished by high hepatic lipid levels.

PPAR-α Modulators as Current and Potential Cancer Treatments

Cancer is one of the leading causes of mortality worldwide. PPAR modulators may hold great potential for the management of cancer patients. Indeed, PPARs are critical sensors and regulators of lipid, and they are able to promote eNOS activation, regulate immunity and inflammation response, and affect proliferation and differentiation of cancer cells. Cancer, a name given to a group of diseases, is characterized by multiple distinctive biological behaviors, including angiogenesis, abnormal cell proliferation, aerobic glycolysis, inflammation, etc. In the last decade, emerging evidence has shown that PPAR-α, a nuclear hormone receptor, can modulate carcinogenesis via exerting effects on one or several characteristic pathological behaviors of cancer. Therefore, the multi-functional PPAR modulators have substantial promise in various types of cancer therapies. This review aims to consolidate the functions of PPAR-α, as well as discuss the current and potential applications of PPAR-α agonists and antagonists in tackling cancer.

Marked effects of novel selective peroxisome proliferator-activated receptor α modulator, pemafibrate in severe hypertriglyceridemia: preliminary report

BACKGROUND

Currently available treatments have only been partly successful in patients with severe hypertriglyceridemia, including those with high serum triglycerides above 1,000 mg/dL (11.3 mmol/L), who often suffer from acute pancreatitis. Pemafibrate is a novel selective peroxisome proliferator-activated receptor α modulator (SPPARMα) which has been developed as an affordable oral tablet in Japan. We herein report the first three patients with severe hypertriglyceridemia who were successfully treated with pemafibrate.

METHODS

Three patients with fasting serum triglyceride (TG) levels above 1,000 mg/dL (11.3 mmol/L) were treated with pemafibrate (0.2-0.4 mg/day, 0.1-0.2 mg BID).

RESULTS

Serum TGs decreased from 2,000-3,000 mg/dL (22.6-33.9 mmol/L) to < 250 mg/dL (2.8 mmol/L) without adverse effects in all three patients. Serum TGs in Patient 1 and 2 decreased from 1,326 mg/dL (15.0 mmol/L) to 164 mg/dL (1.9 mmol/L) and from 2,040 mg/dL (23.1 mmol/L) to 234 mg/dL (2.6 mmol/L), respectively. Patient 3 with type 2 diabetes and 12.1% (109 mmol/mol) hemoglobin A1c had a TG level of 2,300 mg/dL (26.0 mmol/L). Even after glycemic control improved, TG remained high. After pemafibrate administration, TG decreased to 200 mg/dL (2.3 mmol/L). All patients showed no serious adverse events.

CONCLUSIONS

Pemafibrate demonstrated potential efficacy and safety for severe hypertriglyceridemia which may contribute to the prevention of acute pancreatitis, in a manner that can be easily prescribed and used as an oral tablet.

The Effects of New Selective PPARα Agonist CP775146 on Systematic Lipid Metabolism in Obese Mice and Its Potential Mechanism

PURPOSE

Peroxisome proliferator-activated receptor α (PPARα) plays a crucial role in the control of lipid homeostasis. Here, we investigated the effects of CP775146, a new selective PPARα agonist, on lipid metabolism in diet-induced obese mice and its possible mechanism.

METHODS

C57BL/6 mice were fed a high-fat diet (HFD) for 12 weeks to induce obesity and then received CP775146 via intraperitoneal injection for 3 days. The content/morphology of the liver, serum lipid, and liver function was measured. The expression of genes related to lipolysis and synthesis in liver was detected by quantitative real-time PCR (qRT-PCR).

RESULTS

The safe dose of CP775146 was <0.3 mg/kg. CP775146 reduced the serum levels of liver enzymes, such as alanine aminotransferase (ALT) and glutamic-oxaloacetic transaminase (AST) and lipid metabolism-related biomarkers, including triglycerides (TGs) and low-density lipoprotein cholesterol (LDL-c), non-high-density lipoprotein cholesterol (non-HDL-c), and hepatic TG content, at a dosage of 0.1 mg/kg. HFD-induced pathological liver changes improved after CP775146 treatment. The expression of genes involved in liver fatty acid oxidation (acyl-coenzyme A dehydrogenase, long chain (Acadl), acyl-CoA oxidase 1 (Acox-1), carnitine palmitoyltransferase-1 (CPT-1), and enoyl-CoA, hydratase/3-hydroxyacyl CoA dehydrogenase (Ehhadh)) was upregulated in CP775146-treated mice. Furthermore, CP775146 induced the expression of thermogenesis genes (cell death-inducing DFFA-like effector a (Cidea), uncoupling protein 1 (Ucp1)) and lipolysis genes (hormone-sensitive lipase (Hsl), adipose tissue triglyceride lipase (Atgl)) in epididymal white adipose tissue (eWAT), activating browning and thermogenesis.

CONCLUSION

CP775146 efficiently alleviates obesity-induced liver damage, prevents lipid accumulation by activating the liver fatty acid β-oxidation pathway, and regulates the expression of genes that control brown fat-like pathway in eWAT.

Peroxisome proliferator-activated receptor agonists and antagonists: a patent review (2014-present)

Introduction: Peroxisome proliferator-activated receptors (PPARs), PPARα, PPARδ, and PPARγ, play an important role in the regulation of various physiological processes, specifically lipid and energy metabolism and immunity. PPARα agonists (fibrates) and PPARγ agonists (thiazolidinediones) are used for the treatment of hypertriglyceridemia and type 2 diabetes, respectively. PPARδ activation enhances mitochondrial and energy metabolism but PPARδ-acting drugs are not yet available. Many synthetic ligands for PPARs have been developed to expand their therapeutic applications.Areas covered: The authors searched recent patent activity regarding PPAR ligands. Novel PPARα agonists, PPARδ agonists, PPARγ agonists, PPARα/γ dual agonists, and PPARγ antagonists have been claimed for the treatment of metabolic disease and inflammatory disease. Methods for the combination of PPAR ligands with other drugs and expanded application of PPAR agonists for bone and neurological disease have been also claimed.Expert opinion: Novel PPAR ligands and the combination of PPAR ligands with other drugs have been claimed for the treatment of mitochondrial disease, inflammatory/autoimmune disease, neurological disease, and cancer in addition to metabolic diseases including dyslipidemia and type 2 diabetes. Selective therapeutic actions of PPAR ligands should be exploited to avoid adverse effects. More basic studies are needed to elucidate the molecular mechanisms of selective actions.

Association of POR and PPARα polymorphisms with risk of anti-tuberculosis drug-induced liver injury in Western Chinese Han population

OBJECTIVES

Anti-tuberculosis drug-induced liver injury (ATDILI) is a common and sometimes severe adverse drug reaction (ADR). This study was conducted to investigate the relationship between polymorphisms of two genes, cytochrome P450 oxidoreductase (POR) and peroxisome proliferator-activated receptor α (PPARα), and the risk of ATDILI in Western Chinese Han population.

METHODS

A total of 118 tuberculosis (TB) patients with ATDILI and 628 TB patients without ATDILI during anti-TB treatment were recruited from West China Hospital of Sichuan University. DNA was extracted from peripheral blood, and genotypes of the selected 12 single nucleotide polymorphisms (SNPs) (3 SNPs in the POR gene and 9 SNPs in the PPARα gene) were determined. Three genetic models (additive, dominant, and recessive), as well as a haplotype, were used to test the genetic risk of ATDILI. Extended subgroup analysis was conducted according to age, sex and different causality assessments.

RESULTS

The mutant allele, genotype and genetic model of rs3898649 in the POR gene were found to be associated with increased risk of ATDILI, especially in the younger (<50 years old), female and pulmonary tuberculosis subgroup. The other two SNPs rs28737229 and rs4728533 in the POR gene showed only a potential association with susceptibility to ATDILI after Bonferroni correction (P < .05 but P_Bonferroni > .05). The other 9 SNPs loci (rs135549, rs9626730, rs4253712, rs4823613, rs4253730, rs6007662, rs4253728, rs2024929 and rs135561) in the PPARα gene showed no significant differences between ATDILI and non-ATDILI in either allele frequencies or genotype (all P >.05).

CONCLUSIONS

The results demonstrated the strong correlation between POR gene SNP rs3898649 and ATDILI susceptibility, suggesting the importance of POR rs3898649 in the pathogenesis and development of ATDILI. Therefore, our results indicated that POR rs3898649 might be a valuable biomarker potentially involved in ATDILI.

PPARα ligand, AVE8134, and cyclooxygenase inhibitor therapy synergistically suppress lung cancer growth and metastasis

Background

Lung cancer (LC) is one of the leading causes of death worldwide, which highlights the urgent need for better therapies. Peroxisome proliferator-activated nuclear receptor alpha (PPARα), known as a key nuclear transcription factor involved in glucose and lipid metabolism, has been also implicated in endothelial proliferation and angiogenesis. However, the effects and potential mechanisms of the novel PPARα ligand, AVE8134, on LC growth and progression remain unclear.

Methods

A subcutaneous tumour was established in mice by injecting TC-1 lung tumour cells (~ 1 × 10⁶ cells) into their shaved left flank. These mice were treated with three different PPARα ligands: AVE8134 (0.025% in drinking water), Wyeth-14,643 (0.025%), or Bezafibrate (0.3%). Tumour sizes and metastasis between treated and untreated mice were then compared by morphology and histology, and the metabolites of arachidonic acid (AA) were detected by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Inhibition of either Cyp2c44 expression by genetic disruption or cyclooxygenase (COX) activity by indomethacin was used to test the mechanisms by which AVE8134 affects tumour growth.

Results

The pharmacodynamics effects of AVE8134, Wyeth-14,643, and Bezafibrate on lipids control were similar. However, their effects on tumour suppression were different. Eicosanoid profile analysis showed that all PPARα ligands reduced the production of AA-derived epoxyeicosatrienoic acids (EETs) and increased the hydroxyl product, 11-hydroxyeicosatetraenoic acids (11-HETE). Moreover, increased 11-HETE promoted endothelial proliferation, angiogenesis, and subsequent tumour deterioration in a dose-dependent manner possibly via activating the AKT/extracellular signal-regulated kinase (ERK) pathway. The increased 11-HETE partly neutralized the benefits provided by the Cyp2c44-EETs system inhibited by PPARα ligands in tumour-bearing mice. AVE8134 treatment worsened the tumour phenotype in Cyp2c44 knockout mice, indicating that AVE8134 has contradictory effects on tumour growth. The COX inhibitor indomethacin strengthened the inhibitory actions of AVE8134 on tumour growth and metastasis by inhibiting the 11-HETE production in vivo and in vitro.

Conclusion

In this study, we found that the degrees of inhibition on LC growth and metastasis by PPARα ligands depended on their bidirectional regulation on EETs and 11-HETE. Considering their safety and efficacy, the novel PPARα ligand, AVE8134, is a potentially ideal anti-angiogenesis drug for cancer treatment when jointly applied with the COX inhibitor indomethacin.

SPPARM alpha: the Lazarus effect

PURPOSE OF REVIEW

Atherogenic dyslipidaemia, characterized by high plasma triglycerides (a surrogate for triglyceride-rich remnant lipoproteins) and low high-density lipoprotein cholesterol (HDL-C), is prevalent in patients with type 2 diabetes mellitus (T2DM) and contributes to a high modifiable residual cardiovascular risk. Fibrates are effective in managing hypertriglyceridaemia but lack consistent cardiovascular benefit in clinical trials and exhibit pharmacokinetic interaction with statins (gemfibrozil) and renal and hepatic safety issues (fenofibrate). The selective peroxisome proliferator-activated receptor alpha modulator (SPPARMα) paradigm offers potential for improving potency, selectivity and the benefit-risk profile.

RECENT FINDINGS

The present review discusses evidence for the novel SPPARMα agonist, pemafibrate. Clinical trials showed robust lowering of triglyceride-rich lipoproteins, elevation in HDL-C and nonlipid beneficial effects including anti-inflammatory activity. There was a favourable safety profile, with no increase in serum creatinine, evident with fenofibrate, and improved renal and hepatic safety. The cardiovascular outcomes study PROMINENT is critical to confirming the SPPARMα concept by validating reduction in residual cardiovascular risk in patients with T2DM and long-term safety.

SUMMARY

SPPARMα offers a new paradigm for reducing residual cardiovascular risk in T2DM. PROMINENT will be critical to differentiating the first SPPARMα, pemafibrate, as a novel therapeutic class distinct from current fibrates.

Fenofibrate-induced hepatotoxicity: A case with a special feature that is different from those in the LiverTox database

What is known and objective

We report a special case of fenofibrate‐induced acute severe DILI with sudden onset and rapid recovery, which is different from those in the LiverTox database.

Case summary description

The acute severe DILI occurred within only 4 days after fenofibrate initial treatment for hypertriglyceridemia. Liver enzyme levels eventually declined to normal within two weeks after the discontinuation of fenofibrate.

What is new and Conclusion

Early detection of elevated hepatic enzymes after fenofibrate initial treatment helps physicians to avoid delayed diagnosis and subsequent treatment.

Pravastatin and Gemfibrozil Modulate Differently Hepatic and Colonic Mitochondrial Respiration in Tissue Homogenates from Healthy Rats

Statins and fibrates are widely used for the management of hypertriglyceridemia but they also have limitations, mostly due to pharmacokinetic interactions or side effects. It is conceivable that some adverse events like liver dysfunction or gastrointestinal discomfort are caused by mitochondrial dysfunction. Data about the effects of statins and fibrates on mitochondrial function in different organs are inconsistent and partially contradictory. The aim of this study was to investigate the effect of pravastatin (statin) and gemfibrozil (fibrate) on hepatic and colonic mitochondrial respiration in tissue homogenates. Mitochondrial oxygen consumption was determined in colon and liver homogenates from 48 healthy rats after incubation with pravastatin or gemfibrozil (100, 300, 1000 μM). State 2 (substrate dependent respiration) and state 3 (adenosine diphosphate: ADP-dependent respiration) were assessed. RCI (respiratory control index)—an indicator for coupling between electron transport chain system (ETS) and oxidative phosphorylation (OXPHOS) and ADP/O ratio—a parameter for the efficacy of OXPHOS, was calculated. Data were presented as a percentage of control (Kruskal–Wallis + Dunn’s correction). In the liver both drugs reduced state 3 and RCI, gemfibrozil-reduced ADP/O (complex I). In the colon both drugs reduced state 3 but enhanced ADP/O. Pravastatin at high concentration (1000 µM) decreased RCI (complex II). Pravastatin and gemfibrozil decrease hepatic but increase colonic mitochondrial respiration in tissue homogenates from healthy rats.

Molecular modelling, synthesis, and biological evaluations of a 3,5-disubstituted isoxazole fatty acid analogue as a PPARα-selective agonist

The peroxisome proliferator activated receptors (PPARs) are important drug targets in treatment of metabolic and inflammatory disorders. Fibrates, acting as PPARα agonists, have been widely used lipid-lowering agents for decades. However, the currently available PPARα targeting agents show low subtype-specificity and consequently a search for more potent agonists have emerged. In this study, previously isolated oxohexadecenoic acids from the marine algae Chaetoceros karianus were used to design a PPARα-specific analogue. Herein we report the design, synthesis, molecular modelling studies and biological evaluations of the novel 3,5-disubstituted isoxazole analogue 6-(5-heptyl-1,2-oxazol-3-yl)hexanoic acid (1), named ADAM. ADAM shows a clear receptor preference and significant dose-dependent activation of PPARα (EC₅₀ = 47 µM) through its ligand-binding domain (LBD). Moreover, ADAM induces expression of important PPARα target genes, such as CPT1A, in the Huh7 cell line and primary mouse hepatocytes. In addition, ADAM exhibits a moderate ability to regulate PPARγ target genes and drive adipogenesis. Molecular modelling studies indicated that ADAM docks its carboxyl group into opposite ends of the PPARα and -γ LBD. ADAM interacts with the receptor-activating polar network of amino acids (Tyr501, His447 and Ser317) in PPARα, but not in PPARγ LBD. This may explain the lack of PPARγ agonism, and argues for a PPARα-dependent adipogenic function. Such compounds are of interest towards developing new lipid-lowering remedies.

The selective peroxisome proliferator-activated receptor alpha modulator (SPPARMα) paradigm: conceptual framework and therapeutic potential : A consensus statement from the International Atherosclerosis Society (IAS) and the Residual Risk Reduction Initiative (R3i) Foundation

In the era of precision medicine, treatments that target specific modifiable characteristics of high-risk patients have the potential to lower further the residual risk of atherosclerotic cardiovascular events. Correction of atherogenic dyslipidemia, however, remains a major unmet clinical need. Elevated plasma triglycerides, with or without low levels of high-density lipoprotein cholesterol (HDL-C), offer a key modifiable component of this common dyslipidemia, especially in insulin resistant conditions such as type 2 diabetes mellitus. The development of selective peroxisome proliferator-activated receptor alpha modulators (SPPARMα) offers an approach to address this treatment gap. This Joint Consensus Panel appraised evidence for the first SPPARMα agonist and concluded that this agent represents a novel therapeutic class, distinct from fibrates, based on pharmacological activity, and, importantly, a safe hepatic and renal profile. The ongoing PROMINENT cardiovascular outcomes trial is testing in 10,000 patients with type 2 diabetes mellitus, elevated triglycerides, and low levels of HDL-C whether treatment with this SPPARMα agonist safely reduces residual cardiovascular risk.