Macrosomia (birth weight >4000 g) is a product of endocrine dysfunction in utero leading to fetal overgrowth and can lead to maternal and infant morbidity. Fibroblast growth factor 21 (FGF21) and its transcription factor, peroxisome proliferator-activated receptor alpha (PPARα), are found in the placenta and are associated with abnormal metabolic states. Their relationship to the placental dysregulation that leads to macrosomia is unknown. We sought to evaluate the relationship between protein expression of FGF21 and PPARα in placental samples from infants with macrosomia compared to controls (<4000 g) on both the maternal and fetal sides of the placenta. Placental specimens were collected at the time of delivery and protein levels of FGF21 and PPARα were quantified via Western Blot analysis and normalized to GAPDH. Student's t-test, Wilcoxon-Mann-Whitney test, Fisher's exact test, Chi-squared analysis, and Spearman's correlation were used for statistical analyses. Baseline characteristics were similar across both groups. FGF21 and PPARα levels on the maternal side of the placenta did not differ based on presence of macrosomia. PPARα expression was statistically significantly lower on the fetal side in infants with macrosomia. In controls alone, FGF21 and PPARα trended lower on the maternal side compared to the fetal side although this was not statistically significant. PPARα and FGF21 were positively correlated throughout the placenta. We found that lower PPARα expression on the fetal side of placenta was noted in infants with macrosomia, identifying a possible contribution to the growth discrepancy in this group. PPARα and FGF21 are strongly correlated in the human placenta.

Lipid accumulation in hepatocytes is reduced by the activation of the peroxisome proliferator-activated receptor (PPAR) α, which is associated with increased lysosomal acid lipase (LAL) activity, transcription factor EB (TFEB) expression, and mitochondrial β-oxidation.Aim of the study was to assess whether the three isoforms of PPAR, i.e. α, δ and γ, share the same ability to reduce lipid accumulation in hepatocytes and to clarify the involvement of autophagy activation, lysosomal hydrolysis, and mitochondrial β-oxidation in lipid clearance induced by PPARs.

HepG2 cells were treated with oleate/palmitate (O/P) to induce lipid accumulation and exposed to the PPARα agonist fenofibric acid, the γ agonist pioglitazone, the δ agonist seladelpar, or the dual α/γ agonist saroglitazar.

The treatment of HepG2 cells with fenofibric acid, pioglitazone, seladelpar, or saroglitazar halved lipid accumulation induced by O/P. PPAR agonists increased TFEB, p62, and LC3 expression and rescued LAL impairment induced by O/P. Moreover, PPAR agonists significantly increased mitochondrial mass and the expression of genes involved in mitochondrial dynamics and fatty acid catabolism. Interestingly, PPAR agonists lost their ability to reduce lipid accumulation when autophagic flux, LAL activity, or fatty acid transport in the mitochondria were blocked by specific inhibitors.

All PPAR agonists were able to promote the clearance of lipids in cells loaded with long-chain fatty acids. The key role of acid hydrolysis to generate fatty acids, which can be then catabolized in the mitochondria, and the ability of the PPAR system to sustain each phase of this clearing process were elucidated.

Chronic liver diseases, including metabolic dysfunction-associated steatosic liver disease (MASLD) and hepatocellular carcinoma (HCC), are on the rise, potentially due to daily exposure to complex mixtures of chemical compounds forming part of the exposome. Understanding the mechanisms involved in hepatotoxicity of these mixtures is essential to identify common molecular targets that may highlight potential interactions at the molecular level. We illustrated this issue with two families of environmental contaminants, per- and polyfluoroalkyl substances (PFAS) and heterocyclic aromatic amines (HAAs), both of which could be involved in the progression of chronic liver diseases, and whose toxicity may be potentiated by interactions at the level of xenobiotic metabolism. In the study of exposome effects on chronic liver disease, New Approach Methodologies (NAMs) including omics analyses and data from various in vitro, in vivo and in silico approaches, are crucial for improving predictivity of toxicological studies in humans while reducing animal experimentation. Additionally, the development of complex in vitro human liver cell models, such as organoids, is essential to avoid interspecies differences that minimize the risk for humans. All together, these approaches will contribute to construct Adverse Outcome Pathways (AOPs) and could be applied not only to PFAS mixtures but also to other chemical families, providing valuable insights into mixture hepatotoxicity prediction in the study of the exposome. A better understanding of toxicological mechanisms will clarify the role of environmental contaminant mixtures in the development of MASLD and HCC, supporting risk assessment for better treatment, monitoring and prevention strategies.

Metabolic dysfunction-associated steatohepatitis (MASH) is a complex metabolic syndrome, and the development of new drugs is urgently needed. Fatty acid binding proteins (FABPs) and peroxisome proliferator-activated receptors (PPARs) play an important role in the regulation of lipid absorption, metabolism and inflammation. Considering the synergistic effect of FABP and PPAR in the regulation of MASH pathophysiology, the development of FABP/PPAR multiple modulators might be a promising anti-MASH strategy. Herein, the first-in-class FABP/PPAR multiple modulators were designed by hybrid resveratrol and PPARs agonist Elafibranor. Among them, the compound 27 was identified as the optimal FABP/PPAR multiple modulator (FABP1 IC50 = 0.65 μM, FABP4 IC50 = 1.08 μM, PPARα EC50 = 9.19 μM, PPARγ EC50 = 2.20 μM, PPARδ EC50 = 1.58 μM). Further MST assay confirmed the direct interaction of compound 27 and FABP1, providing a robust validation of its target specificity. In MASH mice, compound 27 exhibited a better therapeutic effect than clinical candidate obeticholic acid in ameliorating multiple pathological features of MASH. This study reported the successful discovery of the first-in-class FABP/PPAR multiple modulators, which provided preliminary evidence that such multi-target agents have broad medical prospects.

Metabolic reprogramming represents a hallmark of malignant tumors, manifested through progressive alterations in nutrient utilization patterns during oncogenesis. As fundamental constituents of biological membranes, essential components of signaling pathways, and critical energy substrates, lipids undergo comprehensive metabolic restructuring in neoplastic cells. This lipid remodeling confers enhanced adaptability to sustain uncontrolled proliferation while promoting aggressive migratory phenotypes. Farnesoid X receptor (FXR), a ligand‑activated nuclear receptor responsive to bile acid (BA) derivatives and cholesterol metabolites, orchestrates key aspects of lipid homeostasis. Its regulatory network encompasses cholesterol/BA metabolism, fatty acid (FA) metabolism and plasma lipoprotein trafficking pathways. Emerging evidence positions FXR as a pleiotropic modulator in oncogenesis, with dysregulated expression patterns documented across multiple tumor lineages and premalignant lesions. This mechanistic understanding has propelled FXR‑targeted therapeutics into the forefront of precision oncology development. The present review critically examines the FXR‑lipid axis in lipid‑enriched malignancies, with particular emphasis on its regulatory circuitry governing BA flux and FA turnover.

Metabolic dysfunction-associated fatty liver disease (MAFLD), a condition that stems from hepatic lipid accumulation in the absence of liver damage and overt inflammation, has become the most common hepatic disorder worldwide. Hydrogen sulfide (H2S), a gasotrasmitter, endogenously generated mainly by cystathionine-γ lyase (CTH), cystathionine-β synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (MPST) enzymes, exhibits protective effect in steatosis. Herein, we have demonstrated that CTH and MPST play a central role in MAFLD pathogenesis. Young Cth/Mpst knockout (Cth/Mpst-/-) mice, fed a normal diet, had increased liver mass caused by enhanced hepatic lipid accumulation. Decreased insulin and glucose sensitivity was observed in CTH/MPST-deficient mice. At the cellular level, CTH/MPST inhibition resulted in increased lipid deposition and glucose uptake in hepatocytes. Transcriptome analysis revealed significant upregulation of cholesterol biosynthesis and SREBP-related genes in the liver of Cth/Mpst-/- mice. Transcription factor enrichment analysis of differentially expressed genes between two genotypes, revealed a major impact of LXR, RXR and PPARA in the observed phenotype. Sulfide donor (SG1002) treatment attenuated the fatty liver disease of CTH/MPST-deficient mice. Our findings underline the importance of endogenously produced H2S in the pathogenesis of MAFLD and introduce the Cth/Mpst-/- mouse as a new animal model of early onset hepatic steatosis.

Non-alcoholic fatty liver disease (NAFLD) is a common metabolic liver disease linked to obesity and diabetes. This study aimed to assess whether serum GOT and GPT can predict NAFLD early in at-risk individuals. A retrospective cohort study was conducted using hospital records from the University of Debrecen (2012-2022), including 4886 NAFLD-free individuals at baseline. NAFLD incidence was tracked using ICD-10 codes, with transaminase levels (GOT and GPT) and key metabolic comorbidities analyzed as predictors in a longitudinal design. Survival analysis included Fleming-Harrington tests, Kaplan-Meier, and Nelson-Aalen estimators as well as restricted mean survival time. The Royston-Parmar flexible parametric model was used to assess the time-dependent effects of GOT, GPT, and metabolic risk factors on NAFLD incidence. An elevated GOT was significantly associated with an increased NAFLD hazard (HR = 2.71, 95% CI: 1.31-5.58), as was an elevated GPT (HR = 2.21, 95% CI: 1.09-4.43). Disorders of lipid metabolism showed the strongest association (HR = 3.29, 95% CI: 1.51-7.25). Elevated GOT and GPT levels, in combination with demographic and clinical factors, may serve as valuable prognostic biomarkers for NAFLD progression, underscoring the importance of routine liver enzyme monitoring and comprehensive metabolic management to improve long-term patient outcomes.

Background/Objectives: Hexaraphane, also known as 6-methylsulfinylhexyl isothiocyanate, derived from wasabi (Eutrema japonicum), increases heme oxygenase-1 (HO-1) and aldehyde dehydrogenase 2 (ALDH2) mRNA expression by activating nuclear factor erythroid 2-related factor 2 (Nrf2) in both HepG2 cells and the mouse liver. Given the presence of a peroxisome proliferator-activated receptor (PPAR) response element (PPRE) in the HO-1 and ALDH2 promoters, the present study aimed to determine the effects of hexaraphane on PPARα-associated genes, age-related weight gain, plasma triglyceride levels, and hepatic senescence. Methods: HepG2 cells were treated with hexaraphane to evaluate PPARα target gene expression and PPRE transcriptional activity. Male C57BL/6J young control, aged control, and aged mice administered with hexaraphane for 16 weeks were assessed for food and water intake, body and tissue weights, plasma parameters, and hepatic PPARα-related gene expression. Results: Hexaraphane increased HO-1 mRNA expression levels in HepG2 cells, which was inhibited by GW6471, a PPARα antagonist. It elevated PPRE transcriptional activity and increased carnitine palmitoyltransferase 1A (CPT1A) mRNA expression levels, indicating PPARα activation. In aged mice, hexaraphane intake reduced body weight gain by decreasing the adipose tissue weight. Increased CPT1A expression levels and a tendency toward increased acyl-CoA oxidase 1 (ACOX1) expression levels in the liver of aged mice administered hexaraphane were associated with reduced plasma triglyceride levels and body weight gain. Increased hepatic Sirt1 expression levels in aged mice administered hexaraphane was associated with lower plasma triglyceride levels. Increased hepatic PPARα mRNA expression levels in aged mice administered hexaraphane suggest a positive feedback loop between PPARα and Sirt1. The expression levels of hepatic p21 mRNA, a senescence marker regulated by Sirt1, were upregulated in aged mice but suppressed by hexaraphane intake. Conclusions: Hexaraphane may prevent age-related body weight gain, elevated plasma triglyceride levels, and hepatic senescence by activating PPARα, potentially contributing to longevity.

With increased age, the liver becomes more vulnerable to metabolic dysfunction-associated steatohepatitis (MASH) with fibrosis. Deciphering the complex interplay between aging, the emergence of senescent cells in the liver and MASH fibrosis is critical for developing treatments. Here we report an epigenetic mechanism that links liver aging to MASH fibrosis. We find that upregulation of the chromatin remodeler BAZ2B in a subpopulation of hepatocytes (HEPs) is linked to MASH pathology in patients. Genetic ablation or hepatocyte-specific knockdown of Baz2b in mice attenuates HEP senescence and MASH fibrosis by preserving peroxisome proliferator-activated receptor α (PPARα)-mediated lipid metabolism, which was impaired in both naturally aged and MASH mouse livers. Mechanistically, Baz2b downregulates the expression of genes related to the PPARα signaling pathway by directly binding their promoter regions and reducing chromatin accessibility. Thus, our study unravels the BAZ2B-PPARα-lipid metabolism axis as a link from liver aging to MASH fibrosis, suggesting that BAZ2B is a potential therapeutic target for HEP senescence and fibrosis.

Background: Biological aging is considered a vital risk factor for age-related diseases, but its role in non-alcoholic fatty liver disease (NAFLD) remains uncertain. This study aimed to evaluate the associations of biological aging with NAFLD and the modified effect of genetic susceptibility. Methods: This study included 329,040 participants from the UK Biobank and 6783 participants from the Dongfeng-Tongji Cohort in China. We calculated the chronological age-adjusted biological age as a surrogate measure for biological aging. Accelerated aging was defined as biological age that exceeded chronological age. The association between biological aging and the risk of NAFLD was assessed in the two cohorts. Polygenic risk scores (PRSs) were used to determine genetic susceptibility for NAFLD in the UK Biobank and further analyze the interaction with biological aging. Results: In the UK Biobank, one year older in age-adjusted biological age increased prevalent NAFLD risk by 6%. The hazard ratios (HRs) and 95% confidence intervals (95% CIs) of NAFLD by accelerated aging were 1.35 (1.17, 1.56) and 1.69 (1.54, 1.85) compared to non-aging. In the Dongfeng-Tongji Cohort, biological aging was prospectively associated with NAFLD (accelerated aging: odds ratio (OR) (95% CI) = 1.18 (1.03, 1.36)). In the UK Biobank, high genetic risk was significantly associated with higher NAFLD risk compared to low genetic risk (HRs (95% CIs) = 1.65 (1.40, 1.95)). Analyses of joint effects showed that participants with high PRS and accelerated aging had the highest risk of NAFLD [2.66 (2.98, 3.57) and 2.06 (2.36, 3.96)]. However, biological aging was prospectively associated with NAFLD among participants regardless of genetic risk. There was no significant interaction between genetic risk and biological aging. Conclusions: Accelerated biological aging was associated with a higher risk of NAFLD independent of genetic susceptibility. Identifying populations with accelerated biological aging by the use of surrogate measures and timely intervention may be beneficial for the prevention of NAFLD.

Excess cholesterol accumulation contributes to fibrogenesis in metabolic dysfunction-associated steatohepatitis (MASH), but how hepatic cholesterol metabolism becomes dysregulated in MASH is not completely understood. We show that human fibrotic MASH livers have decreased EH-domain-binding protein 1 (EHBP1), a genome-wide association study (GWAS) locus associated with low-density lipoprotein (LDL) cholesterol, and that EHBP1 loss- and gain-of-function increase and decrease MASH fibrosis in mice, respectively. Mechanistic studies reveal that EHBP1 promotes sortilin-mediated PCSK9 secretion, leading to LDL receptor (LDLR) degradation, decreased LDL uptake, and reduced TAZ, a fibrogenic effector. At a cellular level, EHBP1 deficiency affects the intracellular localization of retromer, a protein complex required for sortilin stabilization. Our therapeutic approach to stabilizing retromer is effective in mitigating MASH fibrosis. Moreover, we show that the tumor necrosis factor alpha (TNF-α)/peroxisome proliferator-activated receptor alpha (PPARα) pathway suppresses EHBP1 in MASH. These data not only provide mechanistic insights into the role of EHBP1 in cholesterol metabolism and MASH fibrosis but also elucidate an interplay between inflammation and EHBP1-mediated cholesterol metabolism.

Aging and aging-associated diseases (AAD), including neurodegenerative disease, cancer, cardiovascular diseases, and diabetes, are inevitable process. With the gradual improvement of life style, life expectancy is gradually extended. However, the extended lifespan has not reduced the incidence of disease, and most elderly people are in ill-health state in their later years. Hence, understanding aging and AAD are significant for reducing the burden of the elderly. Inorganic metal nanoparticles (IMNPs) predominantly include gold, silver, iron, zinc, titanium, thallium, platinum, cerium, copper NPs, which has been widely used to prevent and treat aging and AAD due to their superior properties (essential metal ions for human body, easily synthesis and modification, magnetism). Therefore, a systematic review of common morphological alternations of senescent cells, altered genes and signal pathways in aging and AAD, and biomedical applications of IMNPs in aging and AAD is crucial for the further research and development of IMNPs in aging and AAD. This review focus on the existing research on cellular senescence, aging and AAD, as well as the applications of IMNPs in aging and AAD in the past decade. This review aims to provide cutting-edge knowledge involved with aging and AAD, the application of IMNPs in aging and AAD to promote the biomedical application of IMNPs in aging and AAD.

Intestinal senescence, often characterized by increased oxidative stress, is linked to gastrointestinal disorders such as inflammatory bowel disease and colorectal cancer. While previous studies have suggested that diets rich in food additives, such as the emulsifier Polysorbate 80 (P80), may influence gut health, the impact of P80 exposure on intestinal senescence remains unclear. This study aimed to explore the effects of P80 on intestinal senescence in a senescence-accelerated mouse prone model. The results revealed that P80 exposure could damage the intestinal barrier, induce oxidative stress, and accelerate intestinal senescence. Mechanistically, P80 activated the peroxisome proliferator-activated receptor-α (PPARα) and fatty acid-binding protein 1 (FABP1) axis, increasing intestinal fatty acid absorption and triggering lipotoxicity, which promoted senescence. Additionally, P80 exacerbated D-galactose-induced epithelial cell senescence and lipid accumulation via the PPARα signalling pathway. Importantly, the PPARα antagonist GW6471 mitigated fatty acid uptake and reduced senescence in the intestine. In conclusion, the emulsifier P80 accelerated intestinal senescence by regulating the PPARα-FABP1 axis to induce intestinal fatty acid uptake and lipotoxicity, suggesting new insights into the adverse effects of food additives on gut health.

Per- and polyfluoroalkyl substances (PFAS) are a large group of persistent chemicals that are pervasive in the environment leading to widespread exposure for humans. Perfluorooctanoic acid (PFOA), one of the most commonly measured PFAS in people, disrupts liver and serum lipid homeostasis as shown in animal toxicity and human epidemiological studies. We tested the hypothesis that the effects of PFOA exposure in mice expressing mouse PPARα (mPPARα) are driven largely through PPARα-dependent mechanisms while non-PPARα dependent mechanisms will be more apparent in mice expressing human PPARα (hPPARα). Female and male mPPARα, hPPARα, and PPARα null mice were exposed to PFOA (0.5, 1.4 or 6.2 mg PFOA/L) via drinking water for 14 weeks. Concurrently, mice consumed an American diet containing human diet-relevant amounts of fat and cholesterol. Here, we focused on the effects in female mice, given the dearth of data reported on PFAS-induced effects in females. Increasing the duration of PFOA exposure reduced weight gain in all genotypes of female mice while end-of-study body fat was lower in PFOA exposed hPPARα and PPARα null mice. Serum cholesterol, but not triacylglyceride, concentrations were increased by PFOA exposure in a PPARα-dependent manner. Hepatic triacylglycerides were higher in vehicle-exposed mPPARα and PPARα null mice than hPPARα mice, and PFOA significantly reduced concentrations in mPPARα and PPARα null mice only. In contrast, PFOA increased hepatic cholesterol content in a PPARα-dependent manner. Changes in liver and serum cholesterol may be explained by a strong, PPARα-dependent downregulation of Cyp7a1 expression. PFOA significantly increased PPARα target gene expression in mPPARα mice. Other nuclear receptors were examined: CAR target gene expression was only induced by PFOA in hPPARα and PPARα null mice. PXR target gene expression was induced by PFOA in all genotypes. Results were similar in male mice with two exceptions: (1) vehicle-exposed male mice of all genotypes were equally susceptible to diet-induced hepatic steatosis; (2) male mice drank less water, resulting in lower serum PFOA levels, which may explain the less significant changes in lipid endpoints. Overall, our results show that PFOA modifies triacylglyceride and cholesterol homeostasis independently and that PPARα plays an important role in PFOA-induced increases in liver and serum cholesterol.

Metabolic dysfunction-associated fatty liver disease (MAFLD) encompasses a spectrum of liver diseases ranging from metabolic dysfunction-associated fatty liver to metabolic dysfunction-associated steatohepatitis, which may progress to liver cirrhosis and hepatocellular carcinoma. Several mechanisms, including obesity, insulin resistance, dyslipidemia, inflammation, apoptosis, mitochondrial dysfunction, and reactive oxygen species, have been proposed to underlie the progression of MAFLD. Transcription factors are proteins that specifically bind to DNA sequences to regulate the transcription of target genes. Numerous transcription factors regulate MAFLD by modulating the transcription of genes involved in steatosis, inflammation, apoptosis, and fibrosis. Here, we review the pathological factors associated with MAFLD, with a particular emphasis on the transcription factors that contribute to the progression of MAFLD and their therapeutic implications.

Human single nucleotide variants in peroxisome proliferator-activated receptor-ɑ (PPARɑ) have been associated with beneficial metabolic phenotypes, yet their specific effects on metabolic gene expression are not well defined. Here, we developed a mouse model of a human PPARɑ variant encoding a substitution of valine for alanine at position 227 (V227A) to explore the role of this variant on systemic metabolism. Substitution with this variant in mice reduced plasma triglycerides, without altering body mass or liver lipid accumulation, consistent with phenotypes observed in human cohorts. Gene expression analysis revealed that the V227A variant enhances Ppara target gene expression in mouse liver, consistent with the effects of synthetic PPARɑ agonist treatment. Notably, V227A increased hepatic expression of Lpl, the predominant enzyme responsible for circulating triglyceride hydrolysis. Further characterization revealed that heart tissue from variant mice exhibited increased Lpl expression and triglyceride hydrolysis activity, suggesting that V227A enhances cardiac triglyceride clearance. These findings validate human observational studies and clarify the physiological impact of the V227A PPARɑ variant on plasma triglycerides.

Ketogenesis requires fatty acid flux from intracellular (lipid droplets) and extrahepatic (adipose tissue) lipid stores to hepatocyte mitochondria. However, whether interorganelle contact sites regulate this process is unknown. Recent studies have revealed a role for Calsyntenin-3β (CLSTN3β), an endoplasmic reticulum-lipid droplet contact site protein, in the control of lipid utilization in adipose tissue. Here, we show that Clstn3b expression is induced in the liver by the nuclear receptor PPARα in settings of high lipid utilization, including fasting and ketogenic diet feeding. Hepatocyte-specific loss of CLSTN3β in mice impairs ketogenesis independent of changes in PPARα activation. Conversely, hepatic overexpression of CLSTN3β promotes ketogenesis in mice. Mechanistically, CLSTN3β affects LD-mitochondria crosstalk, as evidenced by changes in fatty acid oxidation, lipid-dependent mitochondrial respiration, and the mitochondrial integrated stress response. These findings define a function for CLSTN3β-dependent membrane contacts in hepatic lipid utilization and ketogenesis.

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease, representing a growing public health burden. While previous studies indicated that lactoferrin (LF) alleviates hepatic lipid accumulation, a hallmark of NAFLD, the mechanisms involved are still elusive. Male C57BL/6 J mice were randomly divided into the control (CON), high-fat, high-cholesterol diet containing cholate (HFCCD), and HFCCD+LF groups and treated for 8 weeks' intervention. Liver and small intestine tissues were analyzed to investigate lipid metabolism and underlying mechanisms. Additionally, gut microbiota composition and short-chain fatty acid (SCFA) levels were assessed. HFCCD feeding induced hepatic steatosis, while LF intervention improved lipid metabolism by reducing fatty acid synthesis and increasing lipolysis in the liver. Mechanistically, LF downregulated the protein expression of serotonin receptor 2A (HTR2A), which is related to lipogenesis, and upregulated the protein expression of peroxisome proliferator-activated receptor α (PPARα), which is one of the pivotal lipolytic genes, and its downstream effector, carnitine palmitoyl transferase-1A (CPT-1A), in the liver. Additionally, LF increased the relative abundance of gut microbiota related to glycolipid metabolism, such as Adlercreutzia, and decreased the relative abundance of 5-HT-promoting gut microbiota, such as Clostridia. Furthermore, LF increased the levels of SCFAs, which positively correlated with the relative abundance of Adlercreutzia. Our study suggests that LF intervention alleviates HFCCD-induced NAFLD in mice, which is potentially associated with regulation of the HTR2A-PPARa-CPT-1A pathway and gut microbiota composition.

Ischemic stroke is a leading cause of death and disability worldwide. Currently, there is an unmet clinical need for pharmacological treatments that can improve ischemic stroke outcomes. In this study, we investigated the role of brain peroxisome proliferator-activated receptor alpha (PPARα) in ischemic stroke pathophysiology. We used a well-established model of cerebral ischemia in PPARα transgenic mice and conducted the RNA sequencing (RNA-seq) of mouse stroke brains harvested 48 h post-middle cerebral artery occlusion (MCAO). PPARα knockout (KO) increased brain infarct size following stroke, indicating a protective role of PPARα in brain ischemia. Our RNA-seq analysis showed that PPARα KO altered the expression of genes in mouse brains with known roles in ischemic stroke pathophysiology. We also identified many other differentially expressed genes (DEGs) upon the loss of PPARα that correlated with increased infarct size in our stroke model. Gene set enrichment analysis (GSEA) and Gene Ontology (GO) analysis revealed the upregulation of gene signatures for the positive regulation of leukocyte proliferation, apoptotic processes, acute-phase response, and cellular component disassembly in mouse stroke brains with PPARα KO. In addition, pathway analysis of our RNA-seq data revealed that TNFα signaling, IL6/STAT3 signaling, and epithelial-mesenchymal transition (EMT) gene signatures were increased in PPARα KO stroke brains. Our study highlights PPARα as an attractive drug target for ischemic stroke due to its transcriptional regulation of inflammation-, apoptosis-, and EMT-related genes in brain tissue following ischemia.

Uric acid (UA), traditionally recognized as an extracellular antioxidant, exhibits paradoxical associations with metabolic disorders such as metabolic dysfunction-associated steatotic liver disease (MASLD), though its mechanistic contributions remain elusive. Here, we integrate multi-modal evidence to explore the role of UA and its oxidative metabolite, allantoin, in MASLD progression. Analysis of UK Biobank data revealed a strong association between elevated UA levels and increased risks of MASLD and type 2 diabetes (T2D). However, Mendelian randomization analysis of over 2 million samples demonstrated causal effects of urate solely on serum triglycerides and T2D risk. Targeted metabolomics in an elderly Chinese cohort identified allantoin, an oxidative by-product of UA, significantly elevated in individuals with dyslipidemia or T2D, with serum allantoin levels positively correlated with fasting glucose, triglycerides, and cholesterol. Animal studies indicated that allantoin exacerbates hepatic lipid accumulation and glucose intolerance in high-fat diet mice, driven by increased hepatic lipid biogenesis and reduced bile acid production. Notably, further research revealed a strong binding affinity of allantoin for PPARα, leading to the suppression of PPARα activity, which promotes the progression of MASLD. These findings underscore the critical role of allantoin, rather than UA, as a critical driver of MASLD development, offering valuable insights for the prediction and management of hepatic metabolic disorders.

Insulin and other growth factors are key regulators of liver gene expression, including in metabolic diseases. Most of the phosphoinositide 3-kinase (PI3K) activity induced by insulin is considered to be dependent on PI3Kα. We used mice lacking p110α, the catalytic subunit of PI3Kα, to investigate its role in the regulation of liver gene expression in health and in metabolic dysfunction-associated steatotic liver disease (MASLD). The absence of hepatocyte PI3Kα reduced maximal insulin-induced PI3K activity and signaling, promoted glucose intolerance in lean mice and significantly regulated liver gene expression, including insulin-sensitive genes, in ad libitum feeding. Some of the defective regulation of gene expression in response to hepatocyte-restricted insulin receptor deletion was related to PI3Kα signaling. In addition, though PI3Kα deletion in hepatocytes promoted insulin resistance, it was protective against steatotic liver disease in diet-induced obesity. In the absence of hepatocyte PI3Kα, the effect of diet-induced obesity on liver gene expression was significantly altered, with changes in rhythmic gene expression in liver. Altogether, this study highlights the specific role of p110α in the control of liver gene expression in physiology and in the metabolic rewiring that occurs during MASLD.

Hyperlipidemia, a metabolic disorder marked by dysregulated lipid metabolism, is a key contributor to the onset and progression of various chronic diseases. Maintaining normal lipid metabolism is critical for health, as disruptions lead to dyslipidemia. The gut and liver play central roles in lipid homeostasis, with their bidirectional communication, known as the gut-liver axis, modulated by bile acids (BAs), gut microbiota, and their metabolites. BAs are essential for regulating their own synthesis, lipid metabolism, and anti-inflammatory responses, primarily through the farnesoid X receptor (FXR) and Takeda G protein-coupled receptor 5 (TGR5). Available evidence suggests that high-fat diet-induced the gut microbiota dysbiosis can induce "leaky gut," allowing toxic microbial metabolites to enter the liver via portal circulation, triggering liver inflammation and lipid metabolism disturbances, ultimately leading to hyperlipidemia. Extensive studies have highlighted the roles of probiotics and Traditional Chinese Medicine (TCM) in restoring gut-liver axis balance and modulating lipid metabolism through regulating the levels of lipopolysaccharides, short-chain fatty acids, and BAs. However, the therapeutic potential of probiotics and TCM for hyperlipidemia remains unclear. Here, firstly, we explore the intricate interplay among gut microbiota and metabolites, lipid metabolism, gut-liver axis, and hyperlipidemia. Secondly, we summarize the mechanisms by which probiotics and TCM can alleviate hyperlipidemia by altering the composition of gut microbiota and regulating lipid metabolism via the gut-liver axis. Finally, we emphasize that more clinical trials of probiotics and TCM are necessary to examine their effects on lipid metabolism and hyperlipidemia.

Adipose triglyceride lipase (ATGL) is an attractive therapeutic target in insulin resistance and metabolic dysfunction-associated steatotic liver disease (MASLD). This study investigated the effects of pharmacological ATGL inhibition on the development of metabolic dysfunction-associated steatohepatitis (MASH) and fibrosis in mice.

Streptozotocin-injected male mice were fed a high-fat diet to induce MASH. Mice receiving the ATGL inhibitor atglistatin (ATGLi) were compared to controls using liver histology, lipidomics, metabolomics, 16s rRNA, and RNA sequencing. Human ileal organoids, HepG2 cells, and Caco2 cells treated with the human ATGL inhibitor NG-497, HepG2 ATGL knockdown cells, gel-shift, and luciferase assays were analysed for mechanistic insights. We validated the benefits of ATGLi on steatohepatitis and fibrosis in a low-methionine choline-deficient mouse model.

ATGLi improved serum liver enzymes, hepatic lipid content, and histological liver injury. Mechanistically, ATGLi attenuated PPARα signalling, favouring hydrophilic bile acid (BA) synthesis with increased Cyp7a1, Cyp27a1, Cyp2c70, and reduced Cyp8b1 expression. Additionally, reduced intestinal Cd36 and Abca1, along with increased Abcg5 expression, were consistent with reduced levels of hepatic triacylglycerol species containing polyunsaturated fatty acids, like linoleic acid, as well as reduced cholesterol levels in the liver and plasma. Similar changes in gene expression associated with PPARα signalling and intestinal lipid transport were observed in ileal organoids treated with NG-497. Furthermore, HepG2 ATGL knockdown cells revealed reduced expression of PPARα target genes and upregulation of genes involved in hydrophilic BA synthesis, consistent with reduced PPARα binding and luciferase activity in the presence of the ATGL inhibitors.

Inhibition of ATGL attenuates PPARα signalling, translating into hydrophilic BA composition, interfering with dietary lipid absorption, and improving metabolic disturbances. Validation with NG-497 opens a new therapeutic perspective for MASLD.

Despite the recent approval of drugs novel mechanistic insights and pathophysiology-oriented therapeutic options for MASLD (metabolic dysfunction-associated steatotic liver disease) are still urgently needed. Herein, we show that pharmacological inhibition of ATGL, the key enzyme in lipid hydrolysis, using atglistatin (ATGLi), improves MASH (metabolic dysfunction-associated steatohepatitis), fibrosis, and key features of metabolic dysfunction in mouse models of MASH and liver fibrosis. Mechanistically, we demonstrated that attenuation of PPARα signalling in the liver and gut favours hydrophilic bile acid composition, ultimately interfering with dietary lipid absorption. One of the drawbacks of ATGLi is its lack of efficacy against human ATGL, thus limiting its clinical applicability. Against this backdrop, we could show that ATGL inhibition using the human inhibitor NG-497 in human primary ileum-derived organoids, Caco2 cells, and HepG2 cells translated into therapeutic mechanisms similar to ATGLi. Collectively, these findings reveal a possible new avenue for MASLD treatment.

The liver is essential for normal fatty acid utilization during fasting. Circulating fatty acids are taken up by hepatocytes and esterified as triacylglycerols for either oxidative metabolization and ketogenesis or export. Whereas the regulation of fatty acid oxidation in hepatocytes is well understood, the uptake and retention of non-esterified fatty acids by hepatocytes is not. Here, we show that murine hepatic stellate cells (HSCs) and their abundantly expressed plasmalemma vesicle-associated protein (PLVAP) control hepatic substrate preference for fasting energy metabolism. HSC-specific ablation of PLVAP in mice elevated hepatic insulin signaling and improved glucose tolerance. Fasted HSC PLVAP knockout mice showed suppressed hepatic fatty acid esterification into di- and triacylglycerols, shifting fasting metabolism from fatty acid oxidation to reliance on carbohydrates. By super-resolution microscopy, we localized HSC PLVAP to caveolae residing along the sinusoidal lumen, supporting a role for HSCs and PLVAP-diaphragmed caveolae in normal fasting metabolism of the liver.

Epidemiologic studies suggest that elevated plasma unconjugated bilirubin confer protection against steatotic liver disease (SLD) in adults. However, evidence supporting this protective role in adolescents remains limited. We aimed to assess the association between serum bilirubin levels and their genetic determinants in protecting against SLD in Chilean adolescents. We conducted a cross-sectional study with 704 adolescents aged 15.4 ± 1 years (52% girls) of the Chilean Growth and Obesity Cohort Study. Ultrasonography echogenicity was used to diagnose SLD. We measured Z-scores of body mass index (z-BMI), total bilirubin (TB), and the genetic determinants of bilirubin (including rs887829 genotypes of UGT1A1 and bilirubin polygenic scores). Multiple logistic regression models evaluated the associations between standardized TB and its genetic determinants with SLD. We found that 1-SD of standardized plasma TB was significantly associated with a 30% reduction in the likelihood of SLD after adjustment by sex, age, z-BMI, and ethnicity (OR = 0.7; 95% CI = 0.50-0.96; p = 0.03). No significant associations were found among the rs887829 genotypes, bilirubin polygenic scores, and SLD in logistic regression models adjusted by covariates. Increased circulating bilirubin levels are unlikely causally associated with protection against SLD, and the cross-sectional association could be due to unmeasured confounding.

Fat-1, an enzyme encoded by the fat-1 gene, is responsible for the conversion of endogenous omega-6 polyunsaturated fatty acids into omega-3 polyunsaturated fatty acids in Caenorhabditis elegans. To better investigate whether the expression of Fat-1 will exert a beneficial function in dyslipidemia and metabolic dysfunction-associated fatty liver disease (MAFLD), we established an adeno-associated virus 9 expressing Fat-1. We found that adeno-associated-virus-mediated expression of Fat-1 markedly reduced the levels of plasma triglycerides and total cholesterol but increased high-density lipoprotein levels in male wild-type hamsters on both chow diet and high-fat diet as well as in chow-diet-fed male LDLR-/- hamsters. Fat-1 ameliorated diet-induced MAFLD in wild-type hamsters by enhancing fatty acid oxidation through the hepatic peroxisome proliferator-activated receptor α (PPARα)-dependent pathway. Mechanistically, Fat-1 increased the levels of multiple lipid derivatives as ligands for PPARα and simultaneously facilitated the nuclear localization of PPARα. Our results provide new insights into the multiple therapeutic potentials of Fat-1 to treat dyslipidemia, MAFLD, and atherosclerosis.

Increased expression of angiotensin-converting enzyme (ACE) by myeloid lineage cells strongly increases the immune activity of these cells, as observed in ACE10/10 mice, which exhibit a marked increase in antitumor and antibactericidal immunity. We report that peroxisome proliferator-activated receptor alpha (PPARα), a transcription factor that regulates genes critical for lipid metabolism, is a key molecule in the enhanced macrophage function induced by ACE. Here, we used a Cre-LoxP approach with LysM-Cre to create a modified ACE10/10 mouse line in which macrophages continue to generate abundant ACE but in which monocyte and macrophage PPARα expression is selectively suppressed. These mice, termed A10-PPARα-Cre, have significantly increased growth of B16-F10 tumors compared with ACE10/10 mice with Cre expression. PPARα depletion impaired cytokine production and antigen-presenting activity in ACE-expressing macrophages, resulting in reduced tumor antigen-specific CD8+ T-cell generation. Additionally, the elevated bactericidal resistance typical of ACE10/10 mice was significantly reduced in A10-PPARα-Cre mice, such that these mice resembled WT mice in their resistance to methicillin-resistant Staphylococcus aureus (MRSA) infection. THP-1 cells expressing increased ACE (termed THP-1-ACE) constitute a human macrophage model with increased PPARα that shows enhanced cytotoxicity against tumor cells and better phagocytosis and killing of MRSA. RNA silencing of PPARα in THP-1-ACE cells reduced both tumor cell death and bacterial phagocytosis and clearance. In contrast, the in vivo administration of pemafibrate, a specific agonist of PPARα, to WT and A10-PPARα-Cre mice reduced B16-F10 tumor growth by 24.5% and 25.8%, respectively, but pemafibrate reduced tumors by 57.8% in ACE10/10 mice. With pemafibrate, the number of antitumor CD8+ T cells was significantly lower in A10-PPARα-Cre mice than in ACE10/10 mice. We conclude that PPARα is important in the immune system of myeloid cells, including wild-type cells, and that its increased expression by ACE-expressing macrophages in ACE10/10 mice is indispensable for ACE-dependent functional upregulation of macrophages in both mice and human cells.

Metabolic dysfunction-associated steatotic liver disease (MASLD), the most prevalent liver disease worldwide, continues to rise. More effective therapeutic strategies are urgently needed. We investigated how targeting two key nuclear receptors involved in hepatic energy metabolism, peroxisome proliferator-activated receptor alpha (PPARα) and estrogen-related receptor alpha (ERRα), ameliorates MASLD.

The PPARα agonist pemafibrate and/or ERRα inverse agonist C29 were administered in a short- and long-term Western diet plus fructose model, and a diabetic-background streptozotocin-Western diet model (STZ-WD). Liver and adipose tissue morphology, histological samples, serum metabolites, RNA and protein levels were analysed and scanning electron microscopy was performed. In addition, we performed cell-based assays and immunohistochemistry and immunofluorescence stainings with light and super-resolution confocal microscopy of healthy, MASLD and MASH human livers.

The ligand combinations' efficacy was highlighted by reduced liver steatosis across all mouse models, alongside improvements in body weight, inflammation, and fibrosis in both long-term models. Additionally, tumour formation was prevented in the STZ-WD mice model. Cell-based assays demonstrated that ERRα inhibits PPARα's activity, explaining why ERRα blockage improves inflammatory and lipid metabolism gene profiles and enhances lipid-lowering effects. Complementary RNA sequencing and shotgun proteomics, combined with enrichment analysis, jointly identified downregulated serum amyloid A1/A2 as essential components underlying the combination treatment's effectiveness. MASLD/MASH patient livers showed reduced PPARα and increased ERRα levels supporting disrupted NR crosstalk in the hepatocyte nucleus.

Our study supports that dual nuclear receptor targeting, which simultaneously increases PPARα and diminishes ERRα activity, may represent a viable novel strategy against MASLD.

Our research introduces a novel therapeutic strategy against MASLD by simultaneously increasing PPARα activity while diminishing ERRα activity. With PPARα agonists already tested in phase III clinical trials, ERRα ligands/modulators need further (clinical) development to make our findings applicable to both MASLD patients and physicians.

Nonalcoholic steatohepatitis (NASH) is emerging as a major cause of liver transplantation and hepatocellular carcinoma (HCC). Regrettably, its pathological mechanisms are still not fully comprehended. GTP-binding protein 8 (GTPBP8), belonging to the GTP-binding protein superfamily, assumes a crucial role in RNA metabolism, cell proliferation, differentiation, and signal transduction. Its aberrant expression is associated with oxidative stress and mitochondrial dysfunctions. Nevertheless, its specific functions and mechanisms of action, particularly in NASH, remain elusive. In our current study, we initially discovered that human hepatocytes L02 displayed evident mitochondrial respiratory anomaly, mitochondrial damage, and dysfunction upon treatment with palmitic acids and oleic acids (PO), accompanied by significantly reduced GTPBP8 expression levels through RNA-Seq, RT-qPCR, western blotting, and immunofluorescence assays. We then demonstrated that GTPBP8 overexpression mediated by adenovirus vector (Ad-GTPBP8) markedly attenuate lipid accumulation, inflammatory response, and mitochondrial impair and dysfunction in hepatocytes stimulated by PO. Conversely, adenovirus vector-mediated GTPBP8 knockdown (Ad-shGTPBP8) significantly accelerated lipid deposition, inflammation and mitochondrial damage in PO-treated hepatocytes in vitro. Furthermore, we constructed an in vivo NASH murine model by giving a 16-week high fat high cholesterol diet (HFHC) diet to hepatocyte specific GTPBP8-knockout (GTPBP8HKO) mice. We firstly found that HFHC feeding led to metabolic disorder in mice, including high body weight, blood glucose and insulin levels, and liver dysfunctions, which were accelerated in these NASH mice with GTPBP8 deficiency in hepatocytes. Consistently, GTPBP8HKO remarkably exacerbated the progression of NASH phenotypes induced by HFHC, as proved by the anabatic lipid accumulation, inflammation, fibrosis and reactive oxygen species (ROS) production in liver tissues, which could be largely attributed to the severe mitochondrial damage and dysfunction. Mechanistically, we further identified that GTPBP8 interacted with peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) in hepatocytes. Importantly, the hepaprotective effects of GTPBP8 against mitochondrial dysfunction, oxidative stress and inflammation was largely dependent on PGC-1α expression. Collectively, GTPBP8 may exert a protective role in the progression of NASH, and targeting the GTPBP8/PGC-1α axis may represent a potential strategy for NASH treatment by improving mitochondrial functions.

There is increasing evidence that gut metabolites have a role in the etiology of obesity. This study aimed to investigate the effects of sodium butyrate (NaB) supplementation on the expression of peroxisome proliferator-activated receptor (PPAR) gamma coactivator-1α (PGC-1α), PPAR-α, and uncoupling protein-1 (UCP-1) genes, as well as on the metabolic parameters and anthropometric indices in persons with obesity.

In this triple-blind placebo-controlled randomized clinical trial, 50 individuals with obesity were randomly assigned to NaB (600 mg/day) + hypo-caloric diet or placebo group + hypo-caloric diet for 8 weeks. The study measured the participants' anthropometric characteristics, food consumption, and feelings of hunger in addition to the serum levels of metabolic indices and the mRNA expression of the PGC-1α, PPAR-α, and UCP-1 genes in peripheral blood mononuclear cells (PBMCs).

PGC-1α and UCP-1 genes expression significantly increased in NaB group compared to the placebo at the endpoint. A significant decrease in weight, BMI, and waist circumference (WC) was observed in NaB group. Among the metabolic factors, NaB significantly decreased fasting blood sugar (FBS) (P = 0.04), low-density lipoprotein cholesterol (LDL-C) (P = 0.038) and increased high-density lipoprotein cholesterol (HDL-C) (P = 0.016). NaB could not significantly change serum GLP-1 level.

This study unveiled NaB supplementation alone cannot have significant beneficial effects on anthropometric, and biochemical factors. NaB could affect anthropometric and metabolic risk variables associated with obesity only when prescribed, along with calorie restriction.

This study was registered in the Iranian Registry of Clinical Trials ( https://en.irct.ir/trial/53968 ) on 31 January 2021 (registry number IRCT20190303042905N2).

Hepatic steatosis, commonly referred to as fatty liver disease, is defined by the abnormal buildup of fat within liver cells. Currently, primary treatments mainly focus on lifestyle changes, underscoring a lack of direct pharmacological options. Passion fruit seed extract (PFSE) has been reported to decrease hepatosteatosis; however, the mechanism underlying this effect has not been clarified. Therefore, the objective of this research was to investigate the effects and mechanisms of action of PFSE against oleic acid (OA)-induced hepatosteatosis in HepG2 cells. OA-induced HepG2 cells were analyzed by using various cell-based experiments, including assessments of cytotoxicity, reactive oxygen species (ROS) production, apoptosis, and protein and gene expression. LC-MS-MS analysis showed that PFSE contains a variety of phytochemical compounds such as alkaloids, flavonoids, stilbenoids, coumarins, terpenoids, lipids, and fatty acid derivatives, which have the potential to exhibit various pharmacological activities. In this study, PFSE demonstrated antioxidant, anti-inflammatory, and lipid metabolism-regulating activities. It also influenced key genes related to lipid metabolism, including SREBP-1c, ACC, FASN, PPARα, CPT-1A, LPL, SCD1, and LDLR. The positive effects of PFSE on OA-induced hepatic steatosis in HepG2 cells were modulated through the Akt and ERK signaling pathways, suggesting that PFSE may offer a comprehensive approach to managing hepatic steatosis.

The preprotein convertase, Bacillus subtilis protease/kexin type 9 serine protease (PCSK9), has garnered significant attention as a potential lipid lowering and therapeutic drug target for atherosclerosis (AS). Peroxisome proliferator-activated receptor alpha (PPARα) is expressed in various tissues and has crucial roles in lipid metabolism and the inflammatory response; however, the precise impact of PCSK9 on AS progression through its regulation of PPARα remains uncertain. The present study aimed to examine the impact of introducing stable liver transduction of human derived PCSK9 with a gain of function D374Y mutation (PCSK9DY) into systemic PPARα knockout mice (PPARα-/-) on plasma lipid levels and AS. Enzymatic assays were employed to evaluate plasma lipid concentrations at various time points, and aortic plaque formation and the degree of inflammatory infiltration quantified. Subsequently, we validated our in vivo results using mouse primary peritoneal macrophages (MPMs). Furthermore, AAV8.2-PPARα virus vector was transduced into transgenic mice of human PCSK9(hPCSK9DY-Tg) by tail vein, and the changes of plasma lipid level and AS were detected. PCSK9DY expression exacerbated symptoms of hypercholesterolemia in PPARα-/- mice. En face analysis and quantification of aortic root sections demonstrated a significant increase in aortic plaque area and inflammatory infiltration in PCSK9DY transduced PPARα-/- mice. Secretion of inflammatory cytokines was elevated in PCSK9DY transduced PPARα-/- mice. In vitro, recombinant hPCSK9 protein promotes the foam cell formation and inflammatory cytokines secretion of PPARα-/- MPMs by increasing the expression of SR-A and TLR4/NF-κB pathway proteins. AAV8.2-PPARα virus vector can reduce the plasma lipid level and AS formation in hPCSK9DY-Tg mice. These finding demonstrate that PCSK9DY expression notably facilitated AS progression in PPARα-/- mice by increasing plasma lipid concentrations and inflammation. However, overexpression of PPARα can reduce AS formation in hPCSK9DY-Tg mice.