Gene Expression Profiles Induced by a Novel Selective Peroxisome Proliferator-Activated Receptor α Modulator (SPPARMα) Pemafibrate

Future Directions in Diabetic Retinopathy Treatment: Stem Cell Therapy, Nanotechnology, and PPARα Modulation

This narrative review focuses on innovative treatment approaches to diabetic retinopathy to meet the urgent demand for advancements in managing both the early and late stages of the disease. Recent studies highlight the potential of adipose stem cells and their secreted factors in mitigating the retinal complications of diabetes, with promising results in improving visual acuity and reducing inflammation and angiogenesis in diabetic retinopathy. However, caution is warranted regarding the safety and long-term therapeutic effects of adipose stem cells transplantation. Bone marrow mesenchymal stem cells can also mitigate retinal damage in diabetic retinopathy. Studies demonstrate that bone marrow mesenchymal stem cells-derived exosomes can suppress the Wnt/β-catenin pathway, reducing oxidative stress, inflammation, and angiogenesis in the diabetic retina, offering promise for future diabetic retinopathy treatments. Nanotechnology has the ability to precisely target the retina and minimize systemic side effects. Nanoparticles and nanocarriers offer improved bioavailability, sustained release of therapeutics, and potential for synergistic effects. They can be a new way of effective treatment and prevention of diabetic retinopathy. Activation and modulation of PPARα as a means for diabetic retinopathy treatment has been widely investigated in recent years and demonstrated promising effects in clinical trials. PPARα activation turned out to be a promising therapeutic method for treating dyslipidemia, inflammation, and insulin sensitivity. The combination of PPARα modulators with small molecules offers an interesting perspective for retinal diseases' therapy.

Exosomes derived from apical papilla stem cells improve NASH by regulating fatty acid metabolism and reducing inflammation

BACKGROUND

Apical papilla stem cells (SCAPs) exhibit significant potential for tissue repair, characterized by their anti-inflammatory and pro-angiogenic properties. Exosomes derived from stem cells have emerged as safer alternatives that retain comparable physiological functions. This study explores the therapeutic potential of exosomes sourced from SCAPs in the treatment of non-alcoholic steatohepatitis (NASH).

METHODS

A NASH mouse model was established through the administration of a high-fat diet (HFD), and SCAPs were subsequently isolated for experimental purposes. A cell model of NASH was established in vitro by treating hepatocellular carcinoma cells with oleic acid (OA) and palmitic acid (PA). Exosomes were isolated via differential centrifugation. The mice were treated with exosomes injected into the tail vein, and the hepatocytes were incubated with exosomes in vitro. After the experiment, physiological and biochemical markers were analyzed to assess the effects of exosomes derived from SCAPs on the progression of NASH in both NASH mouse models and NASH cell models.

RESULTS

After exosomes treatment, the weight gain and liver damage induced by HFD were significantly reduced. Additionally, hepatic fat accumulation was markedly alleviated. Mechanistically, exosomes treatment promoted the expression of genes involved in hepatic fatty acid oxidation and transport, while simultaneously suppressing genes associated with fatty acid synthesis. Furthermore, the levels of serum inflammatory cytokines and the mRNA expression of inflammatory markers in liver tissue were significantly decreased. In vitro cell experiments produced similar results.

Effects of Pemafibrate on Reducing Oxidative Stress and Augmenting Angiogenesis in Ischemic Limb Tissue

OBJECTIVE

Oxidative damage is observed in the ischemic limbs of patients with arteriosclerosis obliterans. We investigated whether pemafibrate, a selective peroxisome proliferator-activated receptor alpha modulator, reduced oxidative stress in ischemic limbs and consequently rescued limb damage in model mice.

MATERIALS AND METHODS

We surgically induced hind-limb ischemia in mice and orally administered pemafibrate solution (P-05 group, 0.5 mg/kg/day; P-10 group, 1.0 mg/kg/day) or control solution (control group). Seven days after the surgery, differences in reactive oxygen species (ROS) contents, antioxidative enzyme and transcription factor expression, blood flow, and capillary density in ischemic limbs were assessed.

RESULTS

Tissue ROS levels were lower in the P-05 and P-10 groups compared with those in the control group. Although the tissue expression levels of nuclear factor-erythroid 2-related factor 2 increased in the P-10 group compared with that in the control group, no corresponding changes were observed in the tissue expression of four antioxidative enzymes. The limb salvage rates and capillary densities in ischemic limbs were higher in the P-05 and P-10 groups than that in the control group.

CONCLUSION

Pemafibrate treatment reduced oxidative stress and augmented angiogenesis in ischemic limbs, contributing to prevention of limb damage in mice.

Different Coactivator Recruitment to Human PPARα/δ/γ Ligand-Binding Domains by Eight PPAR Agonists to Treat Nonalcoholic Fatty Liver Disease

Three peroxisome proliferator-activated receptor subtypes, PPARα, PPAR(ß/)δ, and PPARγ, exert ligand-dependent transcriptional control in concert with retinoid X receptors (RXRs) on various gene sets harboring PPAR response elements (PPREs) in their promoter regions. Ligand-bound PPAR/RXR complexes do not directly regulate transcription; instead, they recruit multiprotein coactivator complexes to specific genomic regulatory loci to cooperatively activate gene transcription. Several coactivators are expressed in a single cell; however, a ligand-bound PPAR can be associated with only one coactivator through a consensus LXXLL motif. Therefore, altered gene transcription induced by PPAR subtypes/agonists may be attributed to the recruitment of various coactivator species. Using a time-resolved fluorescence resonance energy transfer assay, we analyzed the recruitment of four coactivator peptides (PGC1α, CBP, SRC1, and TRAP220) to human PPARα/δ/γ-ligand-binding domains (LBDs) using eight PPAR dual/pan agonists (bezafibrate, fenofibric acid, pemafibrate, pioglitazone, elafibranor, lanifibranor, saroglitazar, and seladelpar) that are/were anticipated to treat nonalcoholic fatty liver disease. These agonists all recruited four coactivators to PPARα/γ-LBD with varying potencies and efficacy. Only five agonists (bezafibrate, pemafibrate, elafibranor, lanifibranor, and seladelpar) recruited all four coactivators to PPARδ-LBD, and their concentration-dependent responses differed from those of PPARα/γ-LBD. These results indicate that altered gene expression through consensus PPREs by different PPAR subtypes/agonists may be caused, in part, by different coactivators, which may be responsible for the unique pharmacological properties of these PPAR agonists.

Protective Effect of Pemafibrate Treatment against Diabetic Retinopathy in Spontaneously Diabetic Torii Fatty Rats

Diabetic retinopathy (DR) can cause visual impairment and blindness, and the increasing global prevalence of diabetes underscores the need for effective therapies to prevent and treat DR. Therefore, this study aimed to evaluate the protective effect of pemafibrate treatment against DR, using a Spontaneously Diabetic Torii (SDT) fatty rat model of obese type 2 diabetes. SDT fatty rats were fed either a diet supplemented with pemafibrate (0.3 mg/kg/day) for 16 weeks, starting at 8 weeks of age (Pf SDT fatty: study group), or normal chow (SDT fatty: controls). Normal chow was provided to Sprague-Dawley (SD) rats (SD: normal controls). Electroretinography (ERG) was performed at 8 and 24 weeks of age to evaluate the retinal neural function. After sacrifice, retinal thickness, number of retinal folds, and choroidal thickness were evaluated, and immunostaining was performed for aquaporin-4 (AQP4). No significant differences were noted in food consumption, body weight, or blood glucose level after pemafibrate administration. Triglyceride levels were reduced, and high-density lipoprotein cholesterol levels were increased. Extension of oscillatory potential (OP)1 and OP3 waves on ERG was suppressed in the Pf SDT fatty group. Retinal thickness at 1,500 microns from the optic disc improved in the Pf SDT fatty group. No significant improvements were noted in choroidal thickness or number of retinal folds. Quantitative analyses showed that AQP4-positive regions in the retinas were significantly larger in the Pf SDT fatty group than in the SDT fatty group. The findings suggest that pemafibrate treatment can exert protective effects against DR.

Unmasking the enigma of lipid metabolism in metabolic dysfunction-associated steatotic liver disease: from mechanism to the clinic

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly defined as non-alcoholic fatty liver disease (NAFLD), is a disorder marked by the excessive deposition of lipids in the liver, giving rise to a spectrum of liver pathologies encompassing steatohepatitis, fibrosis/cirrhosis, and hepatocellular carcinoma. Despite the alarming increase in its prevalence, the US Food and Drug Administration has yet to approve effective pharmacological therapeutics for clinical use. MASLD is characterized by the accretion of lipids within the hepatic system, arising from a disarray in lipid provision (whether through the absorption of circulating lipids or de novo lipogenesis) and lipid elimination (via free fatty acid oxidation or the secretion of triglyceride-rich lipoproteins). This disarray leads to the accumulation of lipotoxic substances, cellular pressure, damage, and fibrosis. Indeed, the regulation of the lipid metabolism pathway is intricate and multifaceted, involving a myriad of factors, such as membrane transport proteins, metabolic enzymes, and transcription factors. Here, we will review the existing literature on the key process of lipid metabolism in MASLD to understand the latest progress in this molecular mechanism. Notably, de novo lipogenesis and the roles of its two main transcription factors and other key metabolic enzymes are highlighted. Furthermore, we will delve into the realm of drug research, examining the recent progress made in understanding lipid metabolism in MASLD. Additionally, we will outline prospective avenues for future drug research on MASLD based on our unique perspectives.

Molecular mechanisms and therapeutic perspectives of peroxisome proliferator-activated receptor α agonists in cardiovascular health and disease

The prevalence of cardiovascular disease (CVD) has been rising due to sedentary lifestyles and unhealthy dietary patterns. Peroxisome proliferator-activated receptor α (PPARα) is a nuclear receptor regulating multiple biological processes, such as lipid metabolism and inflammatory response critical to cardiovascular homeostasis. Healthy endothelial cells (ECs) lining the lumen of blood vessels maintains vascular homeostasis, where endothelial dysfunction associated with increased oxidative stress and inflammation triggers the pathogenesis of CVD. PPARα activation decreases endothelial inflammation and senescence, contributing to improved vascular function and reduced risk of atherosclerosis. Phenotypic switch and inflammation of vascular smooth muscle cells (VSMCs) exacerbate vascular dysfunction and atherogenesis, in which PPARα activation improves VSMC homeostasis. Different immune cells participate in the progression of vascular inflammation and atherosclerosis. PPARα in immune cells plays a critical role in immunological events, such as monocyte/macrophage adhesion and infiltration, macrophage polarization, dendritic cell (DC) embedment, T cell activation, and B cell differentiation. Cardiomyocyte dysfunction, a major risk factor for heart failure, can also be alleviated by PPARα activation through maintaining cardiac mitochondrial stability and inhibiting cardiac lipid accumulation, oxidative stress, inflammation, and fibrosis. This review discusses the current understanding and future perspectives on the role of PPARα in the regulation of the cardiovascular system as well as the clinical application of PPARα ligands.

Novel therapeutic approaches in the management of chronic kidney disease: a narrative review

Chronic kidney disease (CKD) remains a pathologic entity with constantly rising incidence and high rates of morbidity and mortality, which are associated with serious cardiovascular complications. Moreover, the incidence of end-stage renal disease tends to increase. The epidemiological trends of CKD warrant the development of novel therapeutic approaches aiming to prevent its development or retard its progression through the control of major risk factors: type 2 diabetes mellitus, arterial hypertension, and dyslipidemia. Contemporary therapeutics such as sodium-glucose cotransporter-2 inhibitors and second-generation mineralocorticoid receptor antagonists are utilized in this direction. Additionally, experimental and clinical studies present novel drug categories that could be employed in managing CKD, such as aldosterone synthesis inhibitors or activators guanylate cyclase, while the role of melatonin should be further tested in the clinical setting. Finally, in this patient population, the use of hypolipidemic agents may provide incremental benefits.

Selective activation of PPARα maintains thermogenic capacity of beige adipocytes

Beige adipocytes are inducible thermogenic adipocytes used for anti-obesity treatment. Beige adipocytes rapidly lose their thermogenic capacity once external cues are removed. However, long-term administration of stimulants, such as PPARγ and β-adrenergic receptor agonists, is unsuitable due to various side effects. Here, we reported that PPARα pharmacological activation was the preferred target for maintaining induced beige adipocytes. Pemafibrate used in clinical practice for dyslipidemia was developed as a selective PPARα modulator (SPPARMα). Pemafibrate administration regulated the thermogenic capacity of induced beige adipocytes, repressed body weight gain, and ameliorated impaired glucose tolerance in diet-induced obese mouse models. The transcriptome analysis revealed that the E-twenty-six transcription factor ELK1 acted as a cofactor of PPARα. ELK1 was mobilized to the Ucp1 transcription regulatory region with PPARα and modulated its expression by pemafibrate. These results suggest that selective activation of PPARα by pemafibrate is advantageous to maintain the function of beige adipocytes.

Current, emerging, and potential therapies for non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) has been identified as the most common chronic liver disease worldwide, with a growing incidence. NAFLD is considered the hepatic manifestation of a metabolic syndrome that emerges from multiple factors (e.g., oxidative stress, metabolic disorders, endoplasmic reticulum stress, cell death, and inflammation). Non-alcoholic steatohepatitis (NASH), an advanced form of NAFLD, has been reported to be a leading cause of cirrhosis and hepatic carcinoma, and it is progressing rapidly. Since there is no approved pharmacotherapy for NASH, a considerable number of therapeutic targets have emerged with the deepening of the research on NASH pathogenesis. In this study, the therapeutic potential and properties of regulating metabolism, the gut microbiome, antioxidant, microRNA, inhibiting apoptosis, targeting ferroptosis, and stem cell-based therapy in NASH are reviewed and evaluated. Since the single-drug treatment of NASH is affected by individual heterogeneous responses and side effects, it is imperative to precisely carry out targeted therapy with low toxicity. Lastly, targeted therapeutic agent delivery based on exosomes is proposed in this study, such that drugs with different mechanisms can be incorporated to generate high-efficiency and low-toxicity individualized medicine.

Low-carbohydrate diets containing plant-derived fat but not animal-derived fat ameliorate heart failure

Cardiovascular disease (CVD) is a global health burden in the world. Although low-carbohydrate diets (LCDs) have beneficial effects on CVD risk, their preventive effects remain elusive. We investigated whether LCDs ameliorate heart failure (HF) using a murine model of pressure overload. LCD with plant-derived fat (LCD-P) ameliorated HF progression, whereas LCD with animal-derived fat (LCD-A) aggravated inflammation and cardiac dysfunction. In the hearts of LCD-P-fed mice but not LCD-A, fatty acid oxidation-related genes were highly expressed, and peroxisome proliferator-activated receptor α (PPARα), which regulates lipid metabolism and inflammation, was activated. Loss- and gain-of-function experiments indicated the critical roles of PPARα in preventing HF progression. Stearic acid, which was more abundant in the serum and heart of LCD-P-fed mice, activated PPARα in cultured cardiomyocytes. We highlight the importance of fat sources substituted for reduced carbohydrates in LCDs and suggest that the LCD-P-stearic acid-PPARα pathway as a therapeutic target for HF.

Retinal degeneration induced in a mouse model of ischemia-reperfusion injury and its management by pemafibrate treatment

Retinal ischemia-reperfusion (I/R) injury is a common cause of visual impairment. To date, no effective treatment is available for retinal I/R injury. In addition, the precise pathological mechanisms still need to be established. Recently, pemafibrate, a peroxisome proliferator-activated receptor α (PPARα) modulator, was shown to be a promising drug for retinal ischemia. However, the role of pemafibrate in preventing retinal I/R injury has not been documented. Here, we investigated how retinal degeneration occurs in a mouse model of retinal I/R injury by elevation of intraocular pressure and examined whether pemafibrate could be beneficial against retinal degeneration. Adult mice were orally administered pemafibrate (0.5 mg/kg/day) for 4 days, followed by retinal I/R injury. The mice were continuously administered pemafibrate once every day until the end of the experiments. Retinal functional changes were measured using electroretinography. Retina, liver, and serum samples were used for western blotting, quantitative PCR, immunohistochemistry, or enzyme linked immunosorbent assay. Retinal degeneration induced by retinal inflammation was prevented by pemafibrate administration. Pemafibrate administration increased the hepatic PPARα target gene expression and serum levels of fibroblast growth factor 21, a neuroprotective molecule in the eye. The expression of hypoxia-response and pro-and anti-apoptotic/inflammatory genes increased in the retina following retinal I/R injury; however, these changes were modulated by pemafibrate administration. In conclusion, pemafibrate is a promising preventive drug for ischemic retinopathies.

Clinically Relevant Dose of Pemafibrate, a Novel Selective Peroxisome Proliferator-Activated Receptor α Modulator (SPPARMα), Lowers Serum Triglyceride Levels by Targeting Hepatic PPARα in Mice

Pemafibrate (PEM) is a novel lipid-lowering drug classified as a selective peroxisome proliferator-activated receptor α (PPARα) modulator whose binding efficiency to PPARα is superior to that of fibrates. This agent is also useful for non-alcoholic fatty liver disease and primary biliary cholangitis with dyslipidemia. The dose of PEM used in some previous mouse experiments is often much higher than the clinical dose in humans; however, the precise mechanism of reduced serum triglyceride (TG) for the clinical dose of PEM has not been fully evaluated. To address this issue, PEM at a clinically relevant dose (0.1 mg/kg/day) or relatively high dose (0.3 mg/kg/day) was administered to male C57BL/6J mice for 14 days. Clinical dose PEM sufficiently lowered circulating TG levels without apparent hepatotoxicity in mice, likely due to hepatic PPARα stimulation and the enhancement of fatty acid uptake and β-oxidation. Interestingly, PPARα was activated only in the liver by PEM and not in other tissues. The clinical dose of PEM also increased serum/hepatic fibroblast growth factor 21 (FGF21) without enhancing hepatic lipid peroxide 4-hydroxynonenal or inflammatory signaling. In conclusion, a clinically relevant dose of PEM in mice efficiently and safely reduced serum TG and increased FGF21 targeting hepatic PPARα. These findings may help explain the multiple beneficial effects of PEM observed in the clinical setting.

Peroxisome Proliferator–Activated Receptor-α: A Pivotal Regulator of the Gastrointestinal Tract

Peroxisome proliferator–activated receptor (PPAR)-α is a ligand-activated transcription factor distributed in various tissues and cells. It regulates lipid metabolism and plays vital roles in the pathology of the cardiovascular system. However, its roles in the gastrointestinal tract (GIT) are relatively less known. In this review, after summarizing the expression profile of PPAR-α in the GIT, we analyzed its functions in the GIT, including physiological control of the lipid metabolism and pathologic mediation in the progress of inflammation. The mechanism of this regulation could be achieved via interactions with gut microbes and further impact the maintenance of body circadian rhythms and the secretion of nitric oxide. These are also targets of PPAR-α and are well-described in this review. In addition, we also highlighted the potential use of PPAR-α in treating GIT diseases and the inadequacy of clinical trials in this field.

Efficacy and Safety of K-877 (Pemafibrate), a Selective PPARα Modulator, in European Patients on Statin Therapy

OBJECTIVE

High plasma triglyceride (TG) is an independent risk factor for cardiovascular disease. Fibrates lower TG levels through peroxisome proliferator-activated receptor α (PPARα) agonism. Currently available fibrates, however, have relatively low selectivity for PPARα. The aim of this trial was to assess the safety, tolerability, and efficacy of K-877 (pemafibrate), a selective PPARα modulator, in statin-treated European patients with hypertriglyceridemia.

RESEARCH DESIGN AND METHODS

A total of 408 statin-treated adults were recruited from 68 European sites for this phase 2, randomized, double-blind, placebo-controlled trial. They had fasting TG between 175 and 500 mg/dL and HDL-cholesterol (HDL-C) ≤50 mg/dL for men and ≤55 mg/dL for women. Participants were randomly assigned to receive placebo or one of six pemafibrate regimens: 0.05 mg twice a day, 0.1 mg twice a day, 0.2 mg twice a day, 0.1 mg once daily, 0.2 mg once daily, or 0.4 mg once daily. The primary end points were TG and non-HDL-C level lowering at week 12.

RESULTS

Pemafibrate reduced TG at all doses (adjusted P value <0.001), with the greatest placebo-corrected reduction from baseline to week 12 observed in the 0.2-mg twice a day treatment group (54.4%). Reductions in non-HDL-C did not reach statistical significance. Reductions in TG were associated with improvements in other markers for TG-rich lipoprotein metabolism, including reductions in apoB48, apoCIII, and remnant cholesterol and an increase in HDL-C levels. Pemafibrate increased LDL-cholesterol levels, whereas apoB100 was unchanged. Pemafibrate was safe and well-tolerated, with only minor increases in serum creatinine and homocysteine concentrations.

CONCLUSIONS

Pemafibrate is effective, safe, and well-tolerated for the reduction of TG in European populations with hypertriglyceridemia despite statin treatment.

Selective PPARα Modulator Pemafibrate and Sodium-Glucose Cotransporter 2 Inhibitor Tofogliflozin Combination Treatment Improved Histopathology in Experimental Mice Model of Non-Alcoholic Steatohepatitis

Ballooning degeneration of hepatocytes is a major distinguishing histological feature of non-alcoholic steatosis (NASH) progression that can lead to cirrhosis and hepatocellular carcinoma (HCC). In this study, we evaluated the effect of the selective PPARα modulator (SPPARMα) pemafibrate (Pema) and sodium-glucose cotransporter 2 (SGLT2) inhibitor tofogliflozin (Tofo) combination treatment on pathological progression in the liver of a mouse model of NASH (STAM) at two time points (onset of NASH progression and HCC survival). At both time points, the Pema and Tofo combination treatment significantly alleviated hyperglycemia and hypertriglyceridemia. The combination treatment significantly reduced ballooning degeneration of hepatocytes. RNA-seq analysis suggested that Pema and Tofo combination treatment resulted in an increase in glyceroneogenesis, triglyceride (TG) uptake, lipolysis and liberated fatty acids re-esterification into TG, lipid droplet (LD) formation, and Cidea/Cidec ratio along with an increased number and reduced size and area of LDs. In addition, combination treatment reduced expression levels of endoplasmic reticulum stress-related genes (Ire1a, Grp78, Xbp1, and Phlda3). Pema and Tofo treatment significantly improved survival rates and reduced the number of tumors in the liver compared to the NASH control group. These results suggest that SPPARMα and SGLT2 inhibitor combination therapy has therapeutic potential to prevent NASH-HCC progression.

Effect of high-fat diet for rats at different stages on glucose and lipid metabolism in offspring and related mechanisms

OBJECTIVES

To study the effect of high-fat diet for maternal Sprague-Dawley rats at different stages on glucose and lipid metabolism in offspring and related mechanisms.

METHODS

According to the diet before pregnancy and during pregnancy and lactation, maternal rats were randomly divided into four groups (n=9 each): CC (control diet before pregnancy and during pregnancy and lactation), HC (high-fat diet before pregnancy and control diet during pregnancy and lactation), CH (control diet before pregnancy and high-fat diet during pregnancy and lactation), and HH (high-fat diet before pregnancy and during pregnancy and lactation), and all offspring rats were given control diet after weaning. The body weight of maternal rats was recorded before and during pregnancy. Male offspring rats were selected from each group at the juvenile stage (3-week old) and the adult stage (12-week old) to measure the levels of fasting blood glucose (FBG) and fasting insulin (FINS) and the levels of triglyceride (TG) and total cholesterol (TC) in the liver. Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) index was calculated, and the area under the curve (AUC) was calculated for glucose tolerance test (GTT) and insulin tolerance test (ITT). Lipid deposition in the liver was observed, and the mRNA and protein expression levels of the key genes in glucose and lipid metabolism (IR, IRS, and AKT), FASN, SREBP1c, and PPARα in the liver were also measured.

RESULTS

Compared with the control diet groups (CC and CH groups), the groups with high-fat diet before pregnancy (HC and HH groups) had a significant increase in body weight (P<0.001). Compared with the CC group, the HC, CH, and HH groups had a significantly greater increase in body weight (P<0.001). Compared with the CC group, the HC, CH, and HH groups had significant increases in body weight, the levels of TG and TC in the liver, and the mRNA and protein expression levels of FASN, SREBP1c, and PPARα in the offspring rats at week 3 after birth (P<0.05), as well as a significant increase in lipid deposition in the liver, with the most significant increase of the parameters in the HH group. Compared with the CC group, the HH group had significant increases in the levels of FBG and FINS, HOMA-IR index, GTT-AUC, ITT-AUC, and the protein expression level of p-IRS in the liver and significant reductions in the mRNA and protein expression levels of IR and IRS in the liver in the offspring rats at week 3 after birth (P<0.05). Compared with the CC group, the HC, CH, and HH groups had significant increases in body weight, the levels of FBG and FINS, HOMA-IR index, GTT-AUC, ITT-AUC, the levels of TG and TC in the liver, protein expression level of p-IRS in the liver, and the mRNA and protein expression levels of FASN, SREBP1c, and PPARα in the offspring rats at week 12 after birth (P<0.05), as well as a significant increase in lipid deposition in the liver, with the most increase of the parameters in the HH group. Compared with the CC group, the HC, CH, and HH groups had significant reductions in the mRNA expression levels of IR, IRS, and AKT and the protein expression levels of IR, IRS, and p-AKT in the offspring rats at week 12 after birth (P<0.05). There were no significant differences in the levels of glucose and lipid metabolism between the HC and CH groups at various stages (P>0.05).

CONCLUSIONS

High-fat diet for rats at different stages before and after pregnancy has different effects on glucose and lipid metabolism of offspring rats, and high-fat diet before pregnancy and during pregnancy and lactation has the greatest effect. The effect of high-fat diet on glucose and lipid metabolism of offspring rats is considered associated with the changes in the expression of genes involved in glucose and lipid metabolism.

Dyslipidemia in Chronic Kidney Disease: Contemporary Concepts and Future Therapeutic Perspectives

BACKGROUND

Chronic kidney disease (CKD) is an increasingly prevalent disease state met with great morbidity and mortality primarily resulting from the high incidence of adverse cardiovascular outcomes. Therapeutic strategies in this patient population aim at controlling modifiable cardiovascular risk factors, including dyslipidemia.

SUMMARY

In this review article, we first provide the latest pathophysiologic evidence regarding the altered dyslipidemia pattern in CKD, followed by its contemporary management according to the latest guidelines. Moreover, we present the current progress regarding the emerging therapeutic strategies. Key Messages: The presence of renal impairment leads to alterations in cholesterol structure, metabolism, and reverse transport paired with increased oxidative stress. Statins remain the cornerstone of dyslipidemia management in patients with kidney dysfunction who are at risk for cardiovascular events. However, their efficacy is debatable in end-stage renal disease under renal replacement therapy. Therefore, novel treatment approaches aiming at hypertriglyceridemia, proprotein convertase subtilisin/kexin type 9, and lipoprotein(a) are under rigorous investigation while the research of gut microbiome might provide additional mechanistic and therapeutic insight.

Pemafibrate Prevents Retinal Dysfunction in a Mouse Model of Unilateral Common Carotid Artery Occlusion

Cardiovascular diseases lead to retinal ischemia, one of the leading causes of blindness. Retinal ischemia triggers pathological retinal glial responses and functional deficits. Therefore, maintaining retinal neuronal activities and modulating pathological gliosis may prevent loss of vision. Previously, pemafibrate, a selective peroxisome proliferator-activated receptor alpha modulator, was nominated as a promising drug in retinal ischemia. However, a protective role of pemafibrate remains untouched in cardiovascular diseases-mediated retinal ischemia. Therefore, we aimed to unravel systemic and retinal alterations by treating pemafibrate in a new murine model of retinal ischemia caused by cardiovascular diseases. Adult C57BL/6 mice were orally administered pemafibrate (0.5 mg/kg) for 4 days, followed by unilateral common carotid artery occlusion (UCCAO). After UCCAO, pemafibrate was continuously supplied to mice until the end of experiments. Retinal function (a-and b-waves and the oscillatory potentials) was measured using electroretinography on day 5 and 12 after UCCAO. Moreover, the retina, liver, and serum were subjected to qPCR, immunohistochemistry, or ELISA analysis. We found that pemafibrate enhanced liver function, elevated serum levels of fibroblast growth factor 21 (FGF21), one of the neuroprotective molecules in the eye, and protected against UCCAO-induced retinal dysfunction, observed with modulation of retinal gliosis and preservation of oscillatory potentials. Our current data suggest a promising pemafibrate therapy for the suppression of retinal dysfunction in cardiovascular diseases.

High-Fat Diet Enhances Neutrophil Adhesion in LDLR-Null Mice Via Hypercitrullination of Histone H3

Neutrophil adhesion on the atheroprone femoral artery of high-fat diet-fed low-density lipoprotein receptor-null mice was enhanced more than in wild-type mice. The inhibition of histone H3 citrullination of neutrophils reversed the enhancement of neutrophil adhesion, suggesting that hypercitrullination contributes to enhanced neutrophil adhesion. Furthermore, pemafibrate reduced the citrullination of histone H3 in these mice. Therefore, the hypercitrullination of histone H3 in neutrophils contributes to atherosclerotic vascular inflammation.

Fenofibrate Protects against Retinal Dysfunction in a Murine Model of Common Carotid Artery Occlusion-Induced Ocular Ischemia

Ocular ischemia is a common cause of blindness and plays a detrimental role in various diseases such as diabetic retinopathy, occlusion of central retinal arteries, and ocular ischemic syndrome. Abnormalities of neuronal activities in the eye occur under ocular ischemic conditions. Therefore, protecting their activities may prevent vision loss. Previously, peroxisome proliferator-activated receptor alpha (PPARα) agonists were suggested as promising drugs in ocular ischemia. However, the potential therapeutic roles of PPARα agonists in ocular ischemia are still unknown. Thus, we attempted to unravel systemic and ocular changes by treatment of fenofibrate, a well-known PPARα agonist, in a new murine model of ocular ischemia. Adult mice were orally administered fenofibrate (60 mg/kg) for 4 days once a day, followed by induction of ocular ischemia by unilateral common carotid artery occlusion (UCCAO). After UCCAO, fenofibrate was continuously supplied to mice once every 2 days during the experiment period. Electroretinography was performed to measure retinal functional changes. Furthermore, samples from the retina, liver, and blood were subjected to qPCR, Western blot, or ELISA analysis. We found that fenofibrate boosted liver function, increased serum levels of fibroblast growth factor 21 (FGF21), one of the neuroprotective molecules in the central nervous system, and protected against UCCAO-induced retinal dysfunction. Our current data suggest a promising fenofibrate therapy in ischemic retinopathies.

Impact of sex on the adaptation of adult mice to long consumption of sweet-fat diet

In rodents, the most adequate model of human diet-induced obesity is obesity caused by the consumption of a sweet-fat diet (SFD), which causes more pronounced adiposity in females than in males. The aim of this work was to determine the sex-associated effect of SFD on the expression of genes related to carbohydrate-lipid metabolism in adult mice. For 10 weeks, male and female С57Bl mice were fed a standard laboratory chow (Control group) or a diet, which consisted of laboratory chow supplemented with sweet cookies, sunflower seeds and lard (SFD group). Weights of body, liver and fat depots, blood concentrations of hormones and metabolites, liver fat, and mRNA levels of genes involved in regulation of energy metabolism in the liver, perigonadal and subcutaneous white adipose tissue (pgWAT, scWAT) and brown adipose tissue (BAT) were measured. SFD increased body weight and insulin resistance in mice of both sexes. Female mice that consumed SFD (SFD females) had a greater increase in adiposity than SFD males. SFD females showed a decreased expression of genes related to lipogenesis (Lpl) and glucose metabolism (G6pc, Pklr) in liver, as well as lipogenesis (Lpl, Slca4) and lipolysis (Lipe) in pgWAT, suggesting reduced energy expenditure. In contrast, SFD males showed increased lean mass gain, plasma insulin and FGF21 levels, expressions of Cpt1α gene in pgWAT and scWAT and Pklr gene in liver, suggesting enhanced lipid and glucose oxidation in these organs. Thus, in mice, there are sex-dependent differences in adaptation to SFD at the transcriptional level, which can help to explain higher adiposity in females under SFD consumtion.

Small-Molecule Modulation of PPARs for the Treatment of Prevalent Vascular Retinal Diseases

Vascular-related retinal diseases dramatically impact quality of life and create a substantial burden on the healthcare system. Age-related macular degeneration, diabetic retinopathy, and retinopathy of prematurity are leading causes of irreversible blindness. In recent years, the scientific community has made great progress in understanding the pathology of these diseases and recent discoveries have identified promising new treatment strategies. Specifically, compelling biochemical and clinical evidence is arising that small-molecule modulation of peroxisome proliferator-activated receptors (PPARs) represents a promising approach to simultaneously address many of the pathological drivers of these vascular-related retinal diseases. This has excited academic and pharmaceutical researchers towards developing new and potent PPAR ligands. This review highlights recent developments in PPAR ligand discovery and discusses the downstream effects of targeting PPARs as a therapeutic approach to treating retinal vascular diseases.

Pemafibrate, a PPAR alpha agonist, attenuates neointima formation after vascular injury in mice fed normal chow and a high-fat diet

Recently, the prevention of cardiovascular events has become one of the most important aims of diabetes care. Peroxisome proliferator-activated receptor (PPAR) agonists have been reported to have vascular protective effects. Here, we examined whether pemafibrate, a selective PPAR alpha agonist, attenuated neointima formation after vascular injury and vascular smooth muscle cell (VSMC) proliferation. We performed endothelial denudation injury in mice treated with a high-fat diet (HFD) or normal chow. Orally administered pemafibrate significantly attenuated neointima formation after vascular injury in HFD and normal chow mice. Interestingly, pemafibrate increased the serum fibroblast growth factor 21 concentration and decreased serum insulin concentrations in HFD mice. In addition, body weight was slightly but significantly decreased by pemafibrate in HFD mice. Pemafibrate, but not bezafibrate, attenuated VSMC proliferation in vitro. The knockdown of PPAR alpha abolished the anti-VSMC proliferation effect of pemafibrate. BrdU assay results revealed that pemafibrate dose-dependently inhibited DNA synthesis in VSMCs. Flow cytometry analysis demonstrated that G1-to-S phase cell cycle transition was significantly inhibited by pemafibrate. Pemafibrate attenuated serum-induced cyclin D1 expression in VSMCs. However, apoptosis was not induced by pemafibrate as assessed by the TUNEL assay. Similar to the in vitro data, VSMC proliferation was also decreased by pemafibrate in mice. These data suggest that pemafibrate attenuates neointima formation after vascular injury and VSMC proliferation by inhibiting cell cycle progression.

Detailed analysis of lipolytic enzymes in a Japanese woman of familial lipoprotein lipase deficiency - Effects of pemafibrate treatment

BACKGROUND

We present here a 72-y-old Japanese woman with lipoprotein lipase (LPL) deficiency and analyzed her lipolytic enzymes in detail before and after pemafibrate treatment.

METHODS

She had a serum triglycerides (TG) of 22.6 mmol/l at a medical checkup at the age of 52 y. She was referred to our hospital at the age of 61 y. Her serum lipoprotein lipase (LPL) concentration was extremely low, suggesting the clinical diagnosis of LPL deficiency. She experienced an event of acute pancreatitis at the age of 65 y.

RESULTS

Next-generation sequencing analysis revealed a homozygous nonsense mutation in the LPL gene, c.1277G > A (p.Trp409Ter). Her serum TG, LPL and hepatic lipase (HL) concentrations were 15.0 mmol/l, 23 ng/ml and 66 ng/ml, respectively. Fifteen minutes after intravenous heparin injection (30 U/kg), her serum TG, LPL and HL concentrations turned to 14.1 mmol/l, 20 ng/ml and 660 ng/ml, respectively. Eight weeks of pemafibrate treatment (0.2 mg/day) caused a modest reductions in serum TG (15.02 → 13.58 mmol/l) and considerable increases in preheparin HL (66 → 76 ng/ml) and PHP-HL (660 → 1118 ng/ml) concentrations and PHP-HL activities (253 → 369U/l) despite almost no effect on LPL concentrations and activities.

CONCLUSIONS

These findings suggest that HL may contribute to the reduction of plasma TG in LPL deficiency.

PPARα Agonist Oral Therapy in Diabetic Retinopathy

Diabetic retinopathy (DR) is an eye condition that develops after chronically poorly-managed diabetes, and is presently the main cause for blindness on a global scale. Current treatments for DR such as laser photocoagulation, topical injection of corticosteroids, intravitreal injection of anti-vascular endothelial growth factor (VEGF) agents and vitreoretinal surgery are only applicable at the late stages of DR and there are possibilities of significant adverse effects. Moreover, the forms of treatment available for DR are highly invasive to the eyes. Safer and more effective pharmacological treatments are required for DR treatment, in particular at an early stage. In this review, we cover recently investigated promising oral pharmacotherapies, the methods of which are safer, easier to use, patient-friendly and pain-free, in clinical studies. We especially focus on peroxisome proliferator-activator receptor alpha (PPARα) agonists in which experimental evidence suggests PPARα activation may be closely related to the attenuation of vascular damages, including lipid-induced toxicity, inflammation, an excess of free radical generation, endothelial dysfunction and angiogenesis. Furthermore, oral administration of selective peroxisome proliferator-activated receptor alpha modulator (SPPARMα) agonists may induce hepatic fibroblast growth factor 21 expression, indirectly resulting in retinal protection in animal studies. Our review will enable more comprehensive approaches for understanding protective roles of PPARα for the prevention of DR development.

Selective Peroxisome Proliferator-Activated Receptor Alpha Modulators (SPPARMα): New Opportunities to Reduce Residual Cardiovascular Risk in Chronic Kidney Disease?

PURPOSE OF REVIEW

Chronic kidney disease (CKD) poses a major global challenge, which is exacerbated by aging populations and the pandemic of type 2 diabetes mellitus. Much of the escalating burden of CKD is due to cardiovascular complications. Current treatment guidelines for dyslipidemia in CKD prioritize low-density lipoprotein cholesterol management, but still leave a high residual cardiovascular risk. Targeting elevated triglycerides and low plasma high-density lipoprotein cholesterol, a common feature of CKD, could offer additional benefit. There are, however, safety issues with current fibrates (peroxisome proliferator-activated receptor alpha [PPARα] agonists), notably the propensity for elevation in serum creatinine, indicating the need for new approaches.

RECENT FINDINGS

Interactions between the ligand and PPARα receptor influence the specificity and potency of receptor binding, and downstream gene and physiological effects. The peroxisome proliferator-activated receptor alpha modulator (SPPARMα) concept aims to modulate the ligand structure so as to enhance binding at the PPARα receptor, thereby improving the ligand's selectivity, potency, and safety profile. This concept has led to the development of pemafibrate, a novel SPPARMα agent. This review discusses evidence that differentiates pemafibrate from current fibrates, especially the lack of evidence for elevation in serum creatinine or worsening of renal function in high-risk patients, including those with CKD. Differentiation of pemafibrate from current fibrates aims to address unmet clinical needs in CKD. The ongoing PROMINENT study will provide critical information regarding the long-term efficacy and safety of pemafibrate in patients with type 2 diabetes mellitus, including those with CKD, and whether the favorable lipid-modifying profile translates to reduction in residual cardiovascular risk.

Peroxisome Proliferator-Activated Receptors and Their Novel Ligands as Candidates for the Treatment of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a major health issue worldwide, frequently associated with obesity and type 2 diabetes. Steatosis is the initial stage of the disease, which is characterized by lipid accumulation in hepatocytes, which can progress to non-alcoholic steatohepatitis (NASH) with inflammation and various levels of fibrosis that further increase the risk of developing cirrhosis and hepatocellular carcinoma. The pathogenesis of NAFLD is influenced by interactions between genetic and environmental factors and involves several biological processes in multiple organs. No effective therapy is currently available for the treatment of NAFLD. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that regulate many functions that are disturbed in NAFLD, including glucose and lipid metabolism, as well as inflammation. Thus, they represent relevant clinical targets for NAFLD. In this review, we describe the determinants and mechanisms underlying the pathogenesis of NAFLD, its progression and complications, as well as the current therapeutic strategies that are employed. We also focus on the complementary and distinct roles of PPAR isotypes in many biological processes and on the effects of first-generation PPAR agonists. Finally, we review novel and safe PPAR agonists with improved efficacy and their potential use in the treatment of NAFLD.

Pemafibrate, a selective PPARα modulator, prevents non-alcoholic steatohepatitis development without reducing the hepatic triglyceride content

Non-alcoholic steatohepatitis (NASH) is characterized by macrovesicular steatosis with ballooning degeneration of hepatocytes, diffused lobular inflammation, and fibrosis. PPAR ligands are promising therapeutic agents in NASH; accordingly, we evaluated the effects of the first clinically available selective PPARα modulator, pemafibrate. We found that pemafibrate improves F4/80-positive macrophage accumulation, ballooning degeneration of hepatocytes, and the non-alcoholic fatty liver disease (NAFLD) activity score without affecting triglyceride (TG) accumulation in the liver of a mouse model of NASH (STAM). A global gene expression analysis indicated that pemafibrate enhances TG hydrolysis and fatty acid β-oxidation as well as re-esterification from dihydroxyacetone 3-phosphate and monoacylglycerol to TG. These changes are accompanied by the induction of genes involved in lipolysis and lipid droplet formation, along with an increased number and reduced size of lipid droplets in pemafibrate-treated livers. Pemafibrate reduced the expression of the cell adhesion molecule Vcam-1, myeloid cell markers, and inflammation- and fibrosis-related genes in STAM mice. Furthermore, pemafibrate significantly reduced VCAM-1 expression induced by high glucose in cultured human umbilical vein endothelial cells. These results suggest that pemafibrate prevents NASH development by reducing myeloid cell recruitment via interactions with liver sinusoidal endothelial cells, without altering hepatic TG accumulation.