Lipid Metabolism Dysfunction Research Articles

Alterations of Oligodendrocyte and Myelin Energy Metabolism in Multiple Sclerosis.

Multiple sclerosis (MS) is a complex autoimmune disease of the central nervous system (CNS), characterized by demyelination and neurodegeneration. Oligodendrocytes play a vital role in maintaining the integrity of myelin, the protective sheath around nerve fibres essential for efficient signal transmission. However, in MS, oligodendrocytes become dysfunctional, leading to myelin damage and axonal degeneration. Emerging evidence suggests that metabolic changes, including mitochondrial dysfunction and alterations in glucose and lipid metabolism, contribute significantly to the pathogenesis of MS. Mitochondrial dysfunction is observed in both immune cells and oligodendrocytes within the CNS of MS patients. Impaired mitochondrial function leads to energy deficits, affecting crucial processes such as impulse transmission and axonal transport, ultimately contributing to neurodegeneration. Moreover, mitochondrial dysfunction is linked to the generation of reactive oxygen species (ROS), exacerbating myelin damage and inflammation. Altered glucose metabolism affects the energy supply required for oligodendrocyte function and myelin synthesis. Dysregulated lipid metabolism results in changes to the composition of myelin, affecting its stability and integrity. Importantly, low levels of polyunsaturated fatty acids in MS are associated with upregulated lipid metabolism and enhanced glucose catabolism. Understanding the intricate relationship between these mechanisms is crucial for developing targeted therapies to preserve myelin and promote neurological recovery in individuals with MS. Addressing these metabolic aspects may offer new insights into potential therapeutic strategies to halt disease progression and improve the quality of life for MS patients.

Alisol B blocks the development of HFD-induced obesity by triggering the LKB1-AMPK signaling in subcutaneous adipose tissue

As a global epidemic disease, obesity causes dysfunction of glucose and lipid metabolism leading to persistently high morbidity and mortality. Given the difficulty to achieve and maintain weight loss through controlling diet and physical exercise, pharmacotherapy is considered an effective treatment for obesity. This investigation revealed that alisol B, a triterpene monomer isolated from the classical Chinese medicine Alisma orientale (Sam.) Juzep, functioned in suppressing adipogenesis and reducing the mass of subcutaneous adipose tissue, resulting in the reduction of weight gain, and improvements of hyperglycemia, hyperlipidemia, and insulin resistance in HFD-induced obese mice. In consistent to the results, alisol B also significantly inhibited adipocyte differentiation and maturation in vitro. Furthermore, our data revealed that the effects of alisol B on adipogenesis were mediated by LKB1-AMPK signaling pathway. In total, alisol B could be a potential lead compound which contributes to the improvement of obesity-related metabolic disorders.

Nuciferine ameliorates high‐fat diet‐induced disorders of glucose and lipid metabolism in obese mice based on the gut–liver axis

AbstractHigh‐fat diets (HFDs) can trigger lipid accumulation, insulin resistance, and inflammatory responses in the body, causing glucose and lipid metabolism dysfunction. This study aimed to explore the role of nuciferine on HFD‐induced disorders of glucose and lipid metabolism in obesity mice models, and further to identify the possible underlying mechanisms. In our experiments, nuciferine effectively ameliorated HFD‐induced insulin resistance by IRS/PI3K/AKT pathway, and alleviated HFD‐induced lipid accumulation via AMPK‐mediated regulation of FAS and ATGL expression. Nuciferine also suppressed HFD‐induced intestinal pathological damage, as evidenced by the improvement of intestinal barrier integrity and the increasing in expressions of tight junction proteins of claudin, ZO‐1, and occludin. In addition, 16S rRNA gene sequencing of the fecal microbiota suggested that nuciferine changed the diversity and the composition of gut microbiota in HFD‐fed mice. Nuciferine decreased the ratio of Firmicutes/Bacteroidetes, the relative abundance of LPS‐producing genus Desulfovibrio and the bacteria which involved in lipid metabolism. In summary, nuciferine ameliorated the disorders of glucose and lipid metabolism in obese mice via balancing the gut–liver axis.

3-tert-Butyl-4-hydroxyanisole Perturbs Differentiation of C3H10T1/2 Mesenchymal Stem Cells into Brown Adipocytes through Regulating Smad Signaling.

3-tert-Butyl-4-hydroxyanisole (3-BHA), one of the most commonly used antioxidants in foodstuffs, has been identified as an environmental endocrine disruptor (EED) with obesogenic activity. Given the increasing concern on EED-caused dysfunction in lipid metabolism, whether 3-BHA could influence the development of brown adipocytes is worthy of being explored. In this study, the effect of 3-BHA on the differentiation of C3H10T1/2 mesenchymal stem cells (MSCs) into brown adipocytes was investigated. Exposure to 3-BHA promoted lipogenesis of the differentiated cells, as evidenced by the increased intracellular lipid accumulation and elevated expressions of adipogenic biomarkers, including peroxisome proliferator-activated receptor γ (PPARγ), Perilipin, Adiponectin, and fatty acid binding protein 4 (FABP4). Surprisingly, the thermogenic capacity of the differentiated cells was compromised as a result of 3-BHA exposure, because neither intracellular mitochondrial contents nor expressions of thermogenic biomarkers, including uncoupling protein 1 (UCP1), peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α), cell-death-inducing DNA fragmentation factor α subunit-like effector A (CIDEA), and PR domain containing 16 (PRDM16), were increased by this chemical. The underlying molecular mechanism exploration revealed that, in contrast to p38 MAPK, 3-BHA stimulation induced phosphorylation of Smad1/5/8 in an exposure time-dependent manner, suggesting that this chemical-triggered Smad signaling was responsible for the shift of C3H10T1/2 MSC differentiation from a brown to white-like phenotype. The finding herein, for the first time, revealed the perturbation of 3-BHA in the development of brown adipocytes, uncovering new knowledge about the obesogenic potential of this emerging chemical of concern.

Plasma lipid metabolites as potential biomarkers for identifying individuals at risk of obesity-induced metabolic complications

Lipidomics studies have indicated an association between obesity and lipid metabolism dysfunction. This study aimed to evaluate and compare cardiometabolic risk factors, and the lipidomic profile in adults and older people. A cross-sectional study was conducted with 72 individuals, divided into two sex and age-matched groups: obese (body mass index—BMI ≥ 30 kg/m2; n = 36) and non-obese (BMI < 30 kg/m2; n = 36). The lipidomic profiles were evaluated in plasma using 1H nuclear magnetic resonance (1H-NMR) spectroscopy. Obese individuals had higher waist circumference (p < 0.001), visceral adiposity index (p = 0.029), homeostatic model assessment insulin resistance (HOMA-IR) (p = 0.010), and triacylglycerols (TAG) levels (p = 0.018). 1H-NMR analysis identified higher amounts of saturated lipid metabolite fragments, lower levels of unsaturated lipids, and some phosphatidylcholine species in the obese group. Two powerful machine learning (ML) models—k-nearest neighbors (kNN) and XGBoost (XGB) were employed to characterize the lipidomic profile of obese individuals. The results revealed metabolic alterations associated with obesity in the NMR signals. The models achieved high accuracy of 86% and 81%, respectively. The feature importance analysis identified signal at 1.50–1.60 ppm (–CO–CH2–CH2–, Cholesterol and fatty acid in TAG, Phospholipids) to have the highest importance in the two models.

Heat-not-burn tobacco products and cardiovascular risk reduction: A systematic review of randomized controlled trials.

Heat-not-burn (HNB) technology by the U.S. Food and Drug Administration has been classified as a modified risk tobacco product, which can be a better option for those populations who cannot give up the habit of smoking. The outlook on the effects of these products is quite controversial in the scientific world. To present the effect of HNB tobacco products on the cardiovascular system, with reference to the existence of possible benefits of the technology. The literature search was conducted in PubMed/Medline, the Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov databases, with reliance on a well-defined guiding research statement. Quality appraisal was performed using the CASP checklist for randomized controlled trials. The search of three databases identified 167 records, and after selection process, 25 randomized controlled trials were eligible for our study's criteria. Twenty studies investigated the effects of HNB products on biomarkers of clinical relevance. Five studies evaluated other functional heart parameters rather than biomarkers. With HNB tobacco products, significant reductions were found in biomarkers of exposure and biological effect related to pathways involved in cardiovascular disease, including inflammation, oxidative stress, lipid metabolism, platelet function, and endothelial dysfunction.

Lipid metabolism dysfunction following symbiont elimination is linked to altered Kennedy pathway homeostasis

Lipid metabolism is critical for insect reproduction, especially for species that invest heavily in the early developmental stages of their offspring. The role of symbiotic bacteria during this process is understudied but likely essential. We examined the role of lipid metabolism during the interaction between the viviparous tsetse fly (Glossina morsitans morsitans) and its obligate endosymbiotic bacteria (Wigglesworthia glossinidia) during tsetse pregnancy. We observed increased CTP:phosphocholine cytidylyltransferase (cct1) expression during pregnancy, which is critical for phosphatidylcholine biosynthesis in the Kennedy pathway. Experimental removal of Wigglesworthia impaired lipid metabolism via disruption of the Kennedy pathway, yielding obese mothers whose developing progeny starve. Functional validation via experimental cct1 suppression revealed a phenotype similar to females lacking obligate Wigglesworthia symbionts. These results indicate that, in Glossina, symbiont-derived factors, likely B vitamins, are critical for the proper function of both lipid biosynthesis and lipolysis to maintain tsetse fly fecundity.

The Chinese herbal medicine Fufang Zhenzhu Tiaozhi ameliorates diabetic cardiomyopathy by regulating cardiac abnormal lipid metabolism and mitochondrial dynamics in diabetic mice

Diabetic cardiomyopathy (DCM) is an important complication leading to the death of patients with diabetes, but there is no effective strategy for clinical treatments. Fufang Zhenzhu Tiaozhi (FTZ) is a patent medicine that is a traditional Chinese medicine compound preparation with comprehensive effects for the prevention and treatment of glycolipid metabolic diseases under the guidance of “modulating liver, starting pivot and cleaning turbidity”. FTZ was proposed by Professor Guo Jiao and is used for the clinical treatment of hyperlipidemia. This study was designed to explore the regulatory mechanisms of FTZ on heart lipid metabolism dysfunction and mitochondrial dynamics disorder in mice with DCM, and it provides a theoretical basis for the myocardial protective effect of FTZ in diabetes. In this study, we demonstrated that FTZ protected heart function in DCM mice and downregulated the overexpression of free fatty acids (FFAs) uptake-related proteins cluster of differentiation 36 (CD36), fatty acid binding protein 3 (FABP3) and carnitine palmitoyl transferase 1 (CPT1). Moreover, FTZ treatment showed a regulatory effect on mitochondrial dynamics by inhibiting mitochondrial fission and promoting mitochondrial fusion. We also identified in vitro that FTZ could restore lipid metabolism-related proteins, mitochondrial dynamics-related proteins and mitochondrial energy metabolism in PA-treated cardiomyocytes. Our study indicated that FTZ improves the cardiac function of diabetic mice by attenuating the increase in fasting blood glucose levels, inhibiting the decrease in body weight, alleviating disordered lipid metabolism, and restoring mitochondrial dynamics and myocardial apoptosis in diabetic mouse hearts.

Analytical Techniques for Single-Cell Biochemical Assays of Lipids.

Lipids are essential cellular components forming membranes, serving as energy reserves, and acting as chemical messengers. Dysfunction in lipid metabolism and signaling is associated with a wide range of diseases including cancer and autoimmunity. Heterogeneity in cell behavior including lipid signaling is increasingly recognized as a driver of disease and drug resistance. This diversity in cellular responses as well as the roles of lipids in health and disease drive the need to quantify lipids within single cells. Single-cell lipid assays are challenging due to the small size of cells (∼1 pL) and the large numbers of lipid species present at concentrations spanning orders of magnitude. A growing number of methodologies enable assay of large numbers of lipid analytes, perform high-resolution spatial measurements, or permit highly sensitive lipid assays in single cells. Covered in this review are mass spectrometry, Raman imaging, and fluorescence-based assays including microscopy and microseparations.

Investigating the effect of human apolipoprotein E isoforms on expression level of CLS and MINO genes involved in mitochondrial function in transgenic Drosophila model

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by aberrant lipid metabolism and mitochondrial dysfunction, features related to mitochondria-associated ER membranes (MAM). ApoE is recognized as the major AD risk factor. Human ApoE has three isoforms including Apoε2, Apoε3 and Apoε4. It has revealed that ε4 allele carriers are at higher risk of developing AD than ε3 allele carriers. Given that Apoε4 is a major AD risk factor and that MAM dysfunction in lipid metabolism may affect mitochondrial function, we assessed the expression pattern of cardiolipin synthetase (CLS) and glycerol-3-phosphate acyltransferase 2 (MINO) genes in Drosophila model of AD. To the best of our knowledge, this is the first study to investigate the effect of ApoE isoforms on mitochondrial function in Drosophila model of AD. RNA extraction was performed using glazt2a.gal4.UAS.hapoe transgenic flies harboring Apoε isoforms. Following cDNA synthesis, mRNA expression levels of target (CLS and MINO) and housekeeping (eEF1α) genes were measured by qRT-PCR. Our results did not show a significant decrease in CLS and MINO expression level in Apoɛ3 and Apoɛ4 groups as compared to the control. Although this reduction was not statistically significant, the decreasing trend indicates a kind of disruption in lipid biosynthesis and may directly affect mitochondrial function. Though the impact of Apoɛ4 on AD pathogenesis has been elucidated, the exact mechanism through which Apoɛ4 mediates AD progression is still unknown. Investigating the biology of ApoE isoforms using both human and AD animal models is recommended.

AdipoRon alleviates fatty acid–induced lipid accumulation and mitochondrial dysfunction in bovine hepatocytes by promoting autophagy

During the transition period in dairy cows, high circulating concentrations of nonesterified fatty acids (NEFA) increase hepatic lipid deposits and are considered a major pathological factor for liver damage. We investigated whether AdipoRon, a synthetic small-molecule agonist of adiponectin receptors 1 and 2 shown to prevent liver lipid accumulation in nonruminants, could alleviate NEFA-induced lipid accumulation and mitochondrial dysfunction. Bovine hepatocytes were isolated from 5 healthy Holstein female newborn calves (1 d of age, 30-40 kg, fasting), and independently isolated hepatocytes from at least 3 different calves were used for each subsequent experiment. The composition and concentration of NEFA used in this study were selected according to hematological criteria of dairy cows with fatty liver or ketosis. First, hepatocytes were cultured with various concentrations of NEFA (0, 0.6, 1.2, or 2.4 mM) for 12 h. In a second experiment, hepatocytes were treated with AdipoRon at different concentrations (0, 5, 25, or 50 μM for 12 h) and times (25 μM for 0, 6, 12, or 24 h) with or without NEFA (1.2 mM) treatment. In the last experiment, hepatocytes were treated with AdipoRon (25 μM), NEFA (1.2 mM), or both for 12 h after treatment with or without the autophagy inhibitor chloroquine. Hepatocytes treated with NEFA had increased protein abundance of sterol regulatory element-binding protein 1c (SREBP-1c) and mRNA abundance of acetyl-CoA carboxylase 1 (ACACA), and decreased protein abundance of peroxisome proliferator-activated receptor α (PPARA), proliferator-activated receptor gamma coactivator-1 α (PGC-1α), mitofusin 2 (MFN2), cytochrome c oxidase subunit IV (COX IV), and mRNA abundance of carnitine palmitoyltransferase 1A (CPT1A), along with lower ATP concentrations. AdipoRon treatment reversed these effects, suggesting this compound had a positive effect on lipid metabolism and mitochondrial dysfunction during the NEFA challenge. In addition, upregulated expression of microtubule-associated protein 1 light chain 3-II (LC3-II, encoded by MAP1LC3) and downregulated expression of sequestosome-1 (SQSTM1, also called p62) indicated that AdipoRon enhanced autophagic activity in hepatocytes. The fact that chloroquine impeded the beneficial effects of AdipoRon on lipid accumulation and mitochondrial dysfunction suggested a direct role for autophagy during NEFA challenge. Our results suggest that autophagy is an important cellular mechanism to prevent NEFA-induced lipid accumulation and mitochondrial dysfunction in bovine hepatocytes, which is consistent with other studies. Overall, AdipoRon may represent a promising therapeutic agent to maintain hepatic lipid homeostasis and mitochondrial function in dairy cows during the transition period.

Role of Bmal1 in Type 2 Diabetes Mellitus-Related Glycolipid Metabolic Disorder and Neuropsychiatric Injury: Involved in the Regulation of Synaptic Plasticity and Circadian Rhythms.

Increasing data suggest a crucial role of circadian rhythm in regulating metabolic and neurological diseases, and Bmal1 is regarded as a key regulator of circadian transcription. The aim of this study is to investigate the role of Bmal1 in the disruption of circadian rhythm and neuropsychiatric injuries in type 2 diabetes mellitus (T2DM). A T2DM model was induced by the combination of high-fat-diet (HFD) and streptozotocin (STZ) in vivo or HT-22 cells challenged with palmitic-acid (PA) in vitro. The glucolipid metabolism indicators, behavioral performance, and expression of synaptic plasticity proteins and circadian rhythm-related proteins were detected. These changes were also observed after interference of Bmal1 expression via overexpressed plasmid or small interfering RNAs in vitro. The results showed that HFD/STZ could induce T2DM-like glycolipid metabolic turmoil and abnormal neuropsychiatric behaviors in mice, as indicated by the increased concentrations of fasting blood-glucose (FBG), HbA1c and lipids, the impaired glucose tolerance, and the decreased preference index of novel object or novel arm in the novel object recognition test (NOR) and Y-maze test (Y-maze). Consistently, the protein expression of synaptic plasticity proteins and circadian rhythm-related proteins and the positive fluorescence intensity of MT1B and Bmal1 were decreased in the hippocampus of HFD/STZ-induced mice or PA-challenged HT-22 cells. Furthermore, overexpression of Bmal1 could improve the PA-induced lipid metabolic dysfunction and increase the decreased expressions of synaptic plasticity proteins and circadian rhythm-related proteins, and vice versa. These results suggested a crucial role of Bmal1 in T2DM-related glycolipid metabolic disorder and neuropsychiatric injury, which mechanism might be involved in the regulation of synaptic plasticity and circadian rhythms.

Osteocytes contribute via nuclear receptor PPAR-alpha to maintenance of bone and systemic energy metabolism.

The view that bone and energy metabolism are integrated by common regulatory mechanisms is broadly accepted and supported by multiple strands of evidence. This includes the well-characterized role of the PPARγ nuclear receptor, which is a common denominator in energy metabolism and bone metabolism. Little is known, however, about the role of PPARα nuclear receptor, a major regulator of lipid metabolism in other organs, in bone. A side-by-side comparative study of 5-15 mo old mice with global PPARα deficiency (αKO) and mice with osteocyte-specific PPARα deficiency (αOTKO) in order to parse out the various activities of PPARα in the skeleton that are of local and systemic significance. This study included transcriptome analysis of PPARα-deficient osteocytes, and analyses of bone mass and bone microarchitecture, systemic energy metabolism with indirect calorimetry, and differentiation potential of hematopoietic and mesenchymal bone cell progenitors. These analyses were paired with in vitro studies of either intact or silenced for PPARα MLO-A5 cells to determine PPARα role in osteocyte bioenergetics. In osteocytes, PPARα controls large number of transcripts coding for signaling and secreted proteins which may regulate bone microenvironment and peripheral fat metabolism. In addition, PPARα in osteocytes controls their bioenergetics and mitochondrial response to stress, which constitutes up to 40% of total PPARα contribution to the global energy metabolism. Similarly to αKO mice, the metabolic phenotype of αOTKO mice (both males and females) is age-dependent. In younger mice, osteocyte metabolism contributes positively to global energetics, however, with aging the high-energy phenotype reverts to a low-energy phenotype and obesity develops, suggesting a longitudinal negative effect of impaired lipid metabolism and mitochondrial dysfunction in osteocytes deficient in PPARα. However, bone phenotype was not affected in αOTKO mice except in the form of an increased volume of marrow adipose tissue in males. In contrast, global PPARα deficiency in αKO mice led to enlarged bone diameter with a proportional increase in number of trabeculae and enlarged marrow cavities; it also altered differentiation of hematopoietic and mesenchymal marrow cells toward osteoclast, osteoblast and adipocyte lineages, respectively. PPARα role in bone is multileveled and complex. In osteocytes, PPARα controls the bioenergetics of these cells, which significantly contributes to systemic energy metabolism and their endocrine/paracrine function in controlling marrow adiposity and peripheral fat metabolism.

Precision Medicines for Retinal Lipid Metabolism-Related Pathologies.

Oxidation of lipids and lipoproteins contributes to inflammation processes that promote the development of eye diseases. This is a consequence of metabolism dysregulation; for instance, that of the dysfunctional peroxisomal lipid metabolism. Dysfunction of lipid peroxidation is a critical factor in oxidative stress that causes ROS-induced cell damage. Targeting the lipid metabolism to treat ocular diseases is an interesting and effective approach that is now being considered. Indeed, among ocular structures, retina is a fundamental tissue that shows high metabolism. Lipids and glucose are fuel substrates for photoreceptor mitochondria; therefore, retina is rich in lipids, especially phospholipids and cholesterol. The imbalance in cholesterol homeostasis and lipid accumulation in the human Bruch's membrane are processes related to ocular diseases, such as AMD. In fact, preclinical tests are being performed in mice models with AMD, making this area a promising field. Nanotechnology, on the other hand, offers the opportunity to develop site-specific drug delivery systems to ocular tissues for the treatment of eye diseases. Specially, biodegradable nanoparticles constitute an interesting approach to treating metabolic eye-related pathologies. Among several drug delivery systems, lipid nanoparticles show attractive properties, e.g., no toxicological risk, easy scale-up and increased bioavailability of the loaded active compounds. This review analyses the mechanisms involved in ocular dyslipidemia, as well as their ocular manifestations. Moreover, active compounds as well as drug delivery systems which aim to target retinal lipid metabolism-related diseases are thoroughly discussed.

Abstract 4847: Investigating the transcriptional regulation by estrogen-related receptor alpha (ERRα) under different metabolic conditions

Abstract Estrogen-related receptors (ERRs) are orphan nuclear receptors identified based on their high sequence similarity to estrogen receptors (ERs), but ERRs do not have a known endogenous ligand. ERRs play a primary role in regulating the transcription of genes involved in mitochondrial and lipid metabolism and are abundantly expressed across tissues. Because of ERR’s role in metabolism, it is suggested that they may also play a role in tumor metabolism, where dysfunction in lipid metabolism promotes tumor cell growth. The ERR subfamily is comprised of three isoforms: ERRα, ERRβ, and ERRγ. Studies targeting the ERR isoforms found that the absence of ERRα presents obesity and insulin resistance with an increase in bone mass, deletion of ERRβ causes placental abnormalities and embryonic lethality, and deletion of ERRγ leads to mitochondrial dysfunction. Together, these studies strongly suggest that ERRs, particularly ERR α and γ, function primarily as metabolic regulators, with ERRα being the predominant isoform expressed in the liver. In addition, the mechanisms leading to lipid accumulation vary under different feeding conditions. Previous studies from our lab showed that PTEN and PI3K/AKT signaling regulates ERRa expression and its function. Furthermore, we demonstrated that inhibiting ERRα blocks liver steatosis and steatohepatitis developed in a mouse model where loss of tumor suppressor PTEN drives both steatosis and cancer development. In addition, we found that ERR-PA, a small molecule inhibitor for ERR, attenuated cancer cell growth and proliferation in both mouse hepatocytes and human cancer cell lines. Here, we report transcriptome network regulated by ERRα under different metabolic conditions and further explored its regulation by the PI3K/AKT pathway. A better understanding of the role ERRα plays in physiology will allow further development of ERR-PA as a potential therapy for liver steatohepatitis, which progresses to end stage cirrhosis and ultimately liver cancer. Citation Format: Brittney A. Hua, Chien-yu Chen, Yang Li, Lina He, Bangyan Stiles, Ielyzaveta Slarve. Investigating the transcriptional regulation by estrogen-related receptor alpha (ERRα) under different metabolic conditions. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4847.

371 Activated PPARβ/QKI Signaling in Macrophage/Microglia Sensitizes Glioblastoma to Immunotherapy

INTRODUCTION: Glioblastomas (GBMs) share overwhelmingly immunosuppressive tumor microenvironments that are enriched in glioblastoma-associated macrophages and microglia (GAMs). Notably, GAMs have distinctive reshuffling of lipid composition and dysfunctional lipid metabolism. The peroxisome proliferator-activated receptor (PPAR) family members are master regulators of lipid metabolism in macrophages. One of the PPARs, PPARβ is a pivotal modulator of lipid metabolism in macrophages that orchestrates timely disposal of GBM cells. METHODS: Co-immunoprecipitation using an anti-Qki antibody was followed by detecting PPARβ. PPARβ and QKI levels were compared between GAMs inside GBMs and paired macrophages/microglia outside GBMs, as well as human low-grade versus high-grade gliomas. Survival was collected from CX3CR1-CreERT2; PpardL/L/Qki+/+ mice (PPARβ KO) (Ppard is the gene name for PPARβ), CX3CR1-CreERT2; Ppard+/+/QkiL/L mice (QKI KO) and control CX3CR1-CreERT2; Ppard+/+/Qki+/+ (Ctrl) mice given tamoxifen when implanted with GL261 cells. Survival was collected for GBM bearing mice given PPARβ agonist, KD3010 and/or anti-PD-1 therapy. RESULTS: PPARβ co-activates the QKI-mediated complex, which is an essential mediator of phagocytosis in macrophage/microglia. Moreover, PPARβ/QKI signaling is markedly decreased in GAMs relative to paired macrophages/microglia within boundary brain parenchyma (P &lt; 0.001). Myeloid cell–specific PPARβ; or QKI knockout shorten overall survival of GBM–bearing mice (P &lt; 0.05), and inhibited PPARβ/QKI signaling in GAMs correlates with grade progression in human gliomas (P &lt; 0.01) and worse prognosis for GBM (P = 0.0034). Therapeutically, PPARβ agonist plus anti-PD-1 greatly prolongs survival of mice GBMs relative to anti-PD-1 monotherapy (P &lt; 0.05). CONCLUSIONS: We characterize dysfunctional lipid metabolism in GAMs and elucidates the mechanism underlying immunosuppression of GAMs caused by PPARβ/QKI loss. The study supports for therapeutic options for restoring PPARβ/QKI-mediated lipid metabolism in GAMs and development of novel strategies to sensitize GBM to immunotherapy.

Metabolic syndrome in patients with gout

Introduction. The definition of metabolic syndrome is not yet consistent. However, many studies have been conducted in the latest decades about the effect of increased uric acid on metabolic syndrome development. Large epidemiological studies on the association between hyperuricemia and MS showed that increased concentration of serum urea is often observed in subjects with metabolic syndrome. The aim of the study was to characterize specific dysmetabolic changes and features of extraarticular evolution in patients with gout. Materials and methods. A descriptive study was conducted that included 501 patients with gout. The mean age of gout (423 men and 78 women) was 49.2 (36.9; 59.9). The diagnosis of gout was established according to the classification criteria for gout ACR/EULAR 2015. The raw data was processed in SPSS version 26.0. Results. According to our data, the highest severity of obesity and LDL-cholesterol was detected in those with tophaceous gout, which also caused an increase in the frequency of high blood pressure and type 2 diabetes, with age differences in the frequency of detection of metabolic syndrome and insulin resistance. Our data have noted that serum levels of uric acid correlated with the risk of developing both metabolic syndrome as well as its components - obesity, hypertension, and dyslipidemia, but inversely correlated with hyperglycemia. Conclusions. Gout is associated with a severe lipid metabolism dysfunction, significantly increasing the rate of metabolic syndrome especially among patients with chronic tophaceous gout, than in the group of patients with gout under the age of 59 years. On the other hand, in patients with the onset of gout who are ≤59 years lipid metabolism disorders occur significantly earlier than in patients with the onset of gout at the age of ≥60 years.

381 The role of leucine-rich PPR motif-containing protein (LRPPRC) in myelin lipid metabolism

OBJECTIVES/GOALS: Leigh Syndrome, French Canadian-Type (LSFC) is a neurometabolic disorder caused by mutation of mitochondria-related gene, LRPPRC. White matter lesions and demyelination in central nervous system are common in LSFC. LRPPRC is enriched in myelinating glial cells, yet its role is not known. Our goal is to elucidate its mechanistic role in myelination. METHODS/STUDY POPULATION: We crossed C57BL/6N mice bearing a LRPPRC-loxP allele with mice bearing a Plp-CreERT2 allele. Mice with the Plp-CreERT2 allele expresses a tamoxifen-inducible Cre under the control of the Plp promoter, which drives expression in oligodendrocytes. Using these strains, we can target the deletion of LRPPRC, via tamoxifen injection, in both newly formed myelin and mature myelin. Plp-CreERT2; LRPPRCL/L (LRPPRC-KO) or control littermate mice will be injected for LRPPRC deletion at developmental and maturation stages of myelin. Immunofluorescence and electron microscopy of isolated brain tissues will be used for myelin integrity analysis. Cognitive functions of the mice will be measured via behavioral tests. Lastly, we will submit tissues for lipidomic analyses to observe any lipid metabolite variation. RESULTS/ANTICIPATED RESULTS: Behavioral and motor defects would be expected in LRPPRC-KO mice performing in cognitive function tasks across myelin maturation stages. Electron microscopy-based structure analysis of optic nerve, corpus callosum, and spinal cord should reveal thin or loss of myelin on the axons of LRPPRC-KO compared to control. Immunofluorescence staining of major myelin structural proteins, including myelin proteolipid protein (PLP), myelin basic protein (MBP), and myelin-associated glycoprotein (MAG) would be expected have lower levels in LRPPRC deficient tissues. Since myelin is a lipid-rich species, we would also expect lipid concentrations to be affected. LRPPRC-KO lipidomic analyses of myelin-related lipids should depict lower levels in comparison to control, which would imply dysfunctional lipid metabolism. DISCUSSION/SIGNIFICANCE: There are limited studies in ameliorating neural deficits caused by LS and LSFC. Successful completion of this project would help elucidate the functions of LRPPRC in myelination and lipid metabolism and potentially provide insights for developing novel therapeutic strategies for alleviating the demyelination and neural deficits in LSFC.

Treatment of tubular damage in high-fat-diet-fed obese mice using sodium-glucose co-transporter inhibitors.

A long-term high-fat diet (HFD) causes obesity and changes in renal lipid metabolism and lysosomal dysfunction in mice, causing renal damage. Sodium-glucose co-transporter inhibitors, including phlorizin, exert nephroprotective effects in patients with chronic kidney disease, but the underlying mechanism remains unclear. A HFD or standard diet was fed to adult C57BL/6J male mice, and phlorizin was administered. Lamellar body components of the proximal tubular epithelial cells (PTECs) were investigated. After phlorizin administration in HFD-fed mice, sphingomyelin and ceramide in urine and tissues were assessed and label-free quantitative proteomics was performed using kidney tissue samples. Mitochondrial elongation by fusion was effective in the PTECs of HFD-fed obese mice under phlorizin administration, and many lamellar bodies were found in the apical portion of the S2 segment of the proximal tubule. Phlorizin functioned as a diuretic, releasing lamellar bodies from the apical membrane of PTECs and clearing the obstruction in nephrons. The main component of the lamellar bodies was sphingomyelin. On the first day of phlorizin administration in HFD-fed obese mice, the diuretic effect was increased, and more sphingomyelin was excreted through urine than in vehicle-treated mice. The expressions of three peroxisomal β-oxidation proteins involved in fatty acid metabolism were downregulated after phlorizin administration in the kidneys of HFD-fed mice. Fatty acid elongation protein levels increased with phlorizin administration, indicating an increase in long-chain fatty acids. Lamellar bodies accumulated in the proximal renal tubule of the S2 segment of the HFD-fed mice, indicating that the urinary excretion of lamellar bodies has nephroprotective effects.

4-PBA inhibits hypoxia-induced lipolysis in rat adipose tissue and lipid accumulation in the liver through regulating ER stress.

High-altitude hypoxia may disturb the metabolic modulation and function of both adipose tissue and liver. The endoplasmic reticulum (ER) is a crucial organelle in lipid metabolism and ER stress is closely correlated with lipid metabolism dysfunction. The aim of this study is to elucidate whether the inhibition of ER stress could alleviate hypoxia-induced white adipose tissue (WAT) lipolysis and liver lipid accumulation-mediated hepatic injury. A rat model of high-altitude hypoxia (5500 m) was established using hypobaric chamber. The response of ER stress and lipolysis-related pathways were analyzed in WAT under hypoxia exposure with or without 4-phenylbutyric acid (PBA) treatment. Liver lipid accumulation, liver injury, and apoptosis were evaluated. Hypoxia evoked significant ER stress in WAT, evidenced by increased GRP78, CHOP, and phosphorylation of IRE1α, PERK. Moreover, Lipolysis in perirenal WAT significantly increased under hypoxia, accompanied with increased phosphorylation of hormone-sensitive lipase (HSL) and perilipin. Treatment with 4-PBA, inhibitor of ER stress, effectively attenuated hypoxia-induced lipolysis via cAMP-PKA-HSL/perilipin pathway. In addition, 4-PBA treatment significantly inhibited the increase in fatty acid transporters (CD36, FABP1, FABP4) and ameliorated liver FFA accumulation. 4-PBA treatment significantly attenuated liver injury and apoptosis, which is likely resulting from decreased liver lipid accumulation. Our results highlight the importance of ER stress in hypoxia-induced WAT lipolysis and liver lipid accumulation.