Liver sinusoidal endothelial cells rely on oxidative phosphorylation but avoid processing long-chain fatty acids in their mitochondria.

BACKGROUND: It is generally accepted that endothelial cells (ECs), primarily rely on glycolysis for ATP production, despite having functional mitochondria. However, it is also known that ECs are heterogeneous, and their phenotypic features depend on the vascular bed. Emerging evidence suggests that liver sinusoidal ECs (LSECs), located in the metabolically rich environment of the liver, show high metabolic plasticity. However, the substrate preference for energy metabolism in LSECs remains unclear. METHODS: Investigations were conducted in primary murine LSECs in vitro using the Seahorse XF technique for functional bioenergetic assays, untargeted mass spectrometry-based proteomics to analyse the LSEC proteome involved in energy metabolism pathways, liquid chromatography-tandem mass spectrometry-based analysis of acyl-carnitine species and Raman spectroscopy imaging to track intracellular palmitic acid. RESULTS: This study comprehensively characterized the energy metabolism of LSECs, which were found to depend on oxidative phosphorylation, efficiently fuelled by glucose-derived pyruvate, short- and medium-chain fatty acids and glutamine. Furthermore, despite its high availability, palmitic acid was not directly oxidized in LSEC mitochondria, as evidenced by the acylcarnitine profile and etomoxir's lack of effect on oxygen consumption. However, together with L-carnitine, palmitic acid supported mitochondrial respiration, which is compatible with the chain-shortening role of peroxisomal ß-oxidation of long-chain fatty acids before further degradation and energy generation in mitochondria. CONCLUSIONS: LSECs show a unique bioenergetic profile of highly metabolically plastic ECs adapted to the liver environment. The functional reliance of LSECs on oxidative phosphorylation, which is not a typical feature of ECs, remains to be determined.

Thermal oxidation mechanism of palmitic aicd.

The oxidation and degradation of fats lead to a decrease in the nutritional value of food and pose safety concerns. Saturated fatty acids also hold a significant position in the field of lipid oxidation. In this study, the oxidation products of methyl palmitate were investigated by using gas chromatography mass spectrometry (GC-MS). Seven monohydroperoxides and 72 secondary oxidation products were detected. Combined with density functional theory (DFT) calculations, the formation mechanisms of oxidation products can be summarized into four stages. The initial stage involved the formation of monohydroperoxides and alkanes, followed by the subsequent stage involving methyl x-oxo(hydroxy)hexadecanoates. The third stage involved the formation of methyl ketones, carboxylic acids, and aldehydes, while the final stage involved lactones. Meanwhile, methyl ketones were the most abundant oxidation product, approximately 25 times more abundant than aldehydes; the calculated results agreed well with the experimental results. The establishment of a comprehensive thermal oxidation mechanism for palmitic acid provided a new foundation for future lipid oxidation analyses.

Palmitic acid induces lipid droplet accumulation and senescence in nucleus pulposus cells via ER-stress pathway.

Intervertebral disc degeneration (IDD) is a highly prevalent musculoskeletal disorder affecting millions of adults worldwide, but a poor understanding of its pathogenesis has limited the effectiveness of therapy. In the current study, we integrated untargeted LC/MS metabolomics and magnetic resonance spectroscopy data to investigate metabolic profile alterations during IDD. Combined with validation via a large-cohort analysis, we found excessive lipid droplet accumulation in the nucleus pulposus cells of advanced-stage IDD samples. We also found abnormal palmitic acid (PA) accumulation in IDD nucleus pulposus cells, and PA exposure resulted in lipid droplet accumulation and cell senescence in an endoplasmic reticulum stress-dependent manner. Complementary transcriptome and proteome profiles enabled us to identify solute carrier transporter (SLC) 43A3 involvement in the regulation of the intracellular PA level. SLC43A3 was expressed at low levels and negatively correlated with intracellular lipid content in IDD nucleus pulposus cells. Overexpression of SLC43A3 significantly alleviated PA-induced endoplasmic reticulum stress, lipid droplet accumulation and cell senescence by inhibiting PA uptake. This work provides novel integration analysis-based insight into the metabolic profile alterations in IDD and further reveals new therapeutic targets for IDD treatment.

The composition of chemicals and anti-osteogenic properties in the volatile extracts from Homalomena gigantea rhizome.

In this study, the anti-osteogenic properties of the volatile oil extracted from Homalomena gigantea rhizome using ethyl acetate (EtOAc) and methanol (MeOH) were examined. Gas chromatography-mass spectrometry (GC-MS) was employed for the identification of volatile components. Following this, bioassays were performed to evaluate their effects on osteogenesis, encompassing parameters like cell viability, osteoblast differentiation, collagen synthesis and mineralization. The GC-MS analysis revealed 19 compounds in the EtOAc extract and 36 compounds in the MeOH extract. In the MeOH extract, major constituents included bis(2-ethylhexyl) terephthalate (13.83%), linalool (9.58%), palmitic acid (6.55%) and stearic acid (4.29%). The EtOAc extract contained bis(2-ethylhexyl) terephthalate (16.64%), palmitic acid (5.60%) and stearic acid (3.11%) as the predominant components. Both the EtOAc and MeOH extracts of H. gigantea exhibited promising potential for further investigation in anti-osteoporosis research. These findings contribute to the exploration of natural compounds with potential anti-osteoporotic properties, expanding our understanding of their therapeutic potential.

The differential effects of palmitic acid and oleic acid on the metabolic response of hypothalamic astrocytes from male and female mice.

Diets rich in saturated fats are more detrimental to health than those containing mono- or unsaturated fats. Fatty acids are an important source of energy, but they also relay information regarding nutritional status to hypothalamic metabolic circuits and when in excess can be detrimental to these circuits. Astrocytes are the main site of central fatty acid ß-oxidation, and hypothalamic astrocytes participate in energy homeostasis, in part by modulating hormonal and nutritional signals reaching metabolic neurons, as well as in the inflammatory response to high-fat diets. Thus, we hypothesized that how hypothalamic astrocytes process-specific fatty acids participates in determining the differential metabolic response and that this is sex dependent as males and females respond differently to high-fat diets. Male and female primary hypothalamic astrocyte cultures were treated with oleic acid (OA) or palmitic acid (PA) for 24 h, and an untargeted metabolomics study was performed. A clear predictive model for PA exposure was obtained, while the metabolome after OA exposure was not different from controls. The observed modifications in metabolites, as well as the expression levels of key metabolic enzymes, indicate a reduction in the activity of the Krebs and glutamate/glutamine cycles in response to PA. In addition, there were specific differences between the response of astrocytes from male and female mice, as well as between hypothalamic and cerebral cortical astrocytes. Thus, the response of hypothalamic astrocytes to specific fatty acids could result in differential impacts on surrounding metabolic neurons and resulting in varied systemic metabolic outcomes.

Fabrication of Human Milk Fat Substitute: Based on the Similarity Evaluation Model and Computer Software.

We aimed to obtain the optimal formula for human milk fat substitute (HMFS) through a combination of software and an evaluation model and further verify its practicability through an animal experiment. The results showed that a total of 33 fatty acid (FA) and 63 triglyceride (TAG) molecular species were detected in vegetable oils. Palmitic acid, oleic acid, linoleic acid, 18:1/16:0/18:1, 18:2/16:0/18:2, 18:1/18:1/18:1 and 18:1/18:2/18:1, were the main molecular species among the FAs and TAGs in the vegetable oils. Based on the HMFS evaluation model, the optimal mixed vegetable oil formula was blended with 21.3% palm oil, 2.8% linseed oil, 2.6% soybean oil, 29.9% rapeseed oil and 43.4% maize oil, with the highest score of 83.146. Moreover, there was no difference in the weight, blood routine indices or calcium and magnesium concentrations in the feces of the mice between the homemade mixed vegetable oil (HMVO) group and the commercial mixed vegetable oil (CMVO) group, while nervonic acid (C24:1) and octanoic acid (C8:0) were absorbed easily in the HMVO group. Therefore, these results demonstrate that the mixing of the different vegetable oils was feasible via a combination of computer software and an evaluation model and provided a new way to produce HMFS.

D-Allulose Reduces Hypertrophy and Endoplasmic Reticulum Stress Induced by Palmitic Acid in Murine 3T3-L1 Adipocytes.

Natural rare sugars are an alternative category of sweeteners with positive physiologic and metabolic effects both in in vitro and animal models. D-allulose is a D-fructose epimer that combines 70% sucrose sweetness with the advantage of an extremely low energy content. However, there are no data about the effect of D-allulose against adipose dysfunction; thus, it remains to be confirmed whether D-allulose is useful in the prevention and in treatment of adipose tissue alterations. With this aim, we evaluated D-allulose's preventive effects on lipid accumulation in 3T3-L1 murine adipocytes exposed to palmitic acid (PA), a trigger for hypertrophic adipocytes. D-allulose in place of glucose prevented adipocyte hypertrophy and the activation of adipogenic markers C/EBP-ß and PPARγ induced by high PA concentrations. Additionally, D-allulose pretreatment inhibited the NF-κB pathway and endoplasmic reticulum stress caused by PA, through activation of the Nrf2 pathway. Interestingly, these effects were also observed as D-allulose post PA treatment. Although our data need to be confirmed through in vivo models, our findings suggest that incorporating D-allulose as a glucose substitute in the diet might have a protective role in adipocyte function and support a unique mechanism of action in this sugar as a preventive or therapeutic compound against PA lipotoxicity through the modulation of pathways connected to lipid transport and metabolism.

Astaxanthin prevents bone loss in osteoporotic rats with palmitic acid through suppressing oxidative stress.

OBJECTIVES: The study aimed to assess the role of Astaxanthin (ATX) in palmitic acid(PA) -induced bone loss in Ovariectomized(OVX) rats. METHODS: In the OVX rat model, we observed that PA affects bone metabolism and accelerates bone loss. Additionally, treatment with ATX was able to suppress the deleterious effects of PA and a simultaneous decrease in serum MDA levels and an increase in SOD was observed. RESULTS: In addition, rats treated with ATX were observed to have significantly increased bone mass and elevated activity of SIRT1 and SOD2 in bone tissue. When MC3T3-E1 and RAW264.7 cells induced osteoblast and osteoclast differentiation, the ATX intervention was able to significantly restore the restriction of osteogenic differentiation and the up-regulation of osteoclast differentiation with PA therapy. Furthermore, we confirm that PA damage to cells is caused by increased oxidative stress, and that ATX can target and modulate the activity of SIRT1 to regulate the levels of oxidative stress in cells. CONCLUSION: Summarizing, ATX may inhibit PA-induced bone loss through its antioxidant properties via the SIRT1 signaling pathway.

Stevioside Ameliorates Palmitic Acid-Induced Abnormal Glucose Uptake via the PDK4/AMPK/TBC1D1 Pathway in C2C12 Myotubes.

BACKGROUND: Stevioside (SV) with minimal calories is widely used as a natural sweetener in beverages due to its high sweetness and safety. However, the effects of SV on glucose uptake and the pyruvate dehydrogenase kinase isoenzyme (PDK4) as an important protein in the regulation of glucose metabolism, remain largely unexplored. In this study, we used C2C12 skeletal muscle cells that was induced by palmitic acid (PA) to assess the effects and mechanisms of SV on glucose uptake and PDK4. METHODS: The glucose uptake of C2C12 cells was determined by 2-NBDG; expression of the Pdk4 gene was measured by quantitative real-time PCR; and expression of the proteins PDK4, p-AMPK, TBC1D1 and GLUT4 was assessed by Western blotting. RESULTS: In PA-induced C2C12 myotubes, SV could significantly promote cellular glucose uptake by decreasing PDK4 levels and increasing p-AMPK and TBC1D1 levels. SV could promote the translocation of GLUT4 from the cytoplasm to the cell membrane in cells. Moreover, in Pdk4-overexpressing C2C12 myotubes, SV decreased the level of PDK4 and increased the levels of p-AMPK and TBC1D1. CONCLUSION: SV was found to ameliorate PA-induced abnormal glucose uptake via the PDK4/AMPK/TBC1D1 pathway in C2C12 myotubes. Although these results warranted further investigation for validation, they may provide some evidence of SV as a safe natural sweetener for its use in sugar-free beverages to prevent and control T2DM.

IL-33 Reduces Saturated Fatty Acid Accumulation in Mouse Atherosclerotic Foci.

The cellular and molecular mechanisms of atherosclerosis are still unclear. Type 2 innate lymphocytes (ILC2) exhibit anti-inflammatory properties and protect against atherosclerosis. This study aimed to elucidate the pathogenesis of atherosclerosis development using atherosclerosis model mice (ApoE KO mice) and mice deficient in IL-33 receptor ST2 (ApoEST2 DKO mice). Sixteen-week-old male ApoE KO and ApoEST2 DKO mice were subjected to an 8-week regimen of a high-fat, high-sucrose diet. Atherosclerotic foci were assessed histologically at the aortic valve ring. Chronic inflammation was assessed using flow cytometry and real-time polymerase chain reaction. In addition, saturated fatty acids (palmitic acid) and IL-33 were administered to human aortic endothelial cells (HAECs) to assess fatty acid metabolism. ApoEST2 DKO mice with attenuated ILC2 had significantly worse atherosclerosis than ApoE KO mice. The levels of saturated fatty acids, including palmitic acid, were significantly elevated in the arteries and serum of ApoEST2 DKO mice. Furthermore, on treating HAECs with saturated fatty acids with or without IL-33, the Oil Red O staining area significantly decreased in the IL-33-treated group compared to that in the non-treated group. IL-33 potentially prevented the accumulation of saturated fatty acids within atherosclerotic foci.

The Effect of Sn-2 Palmitate on Blood Glucose, Lipids and Body Composition in Middle-Aged and Elderly Adults: A Randomized, Double-Blinded Controlled Trial.

Sn-2 palmitate is widely used in infant formula. However, little is known about its effects on metabolism and body composition in middle-aged and elderly adults. In a double-blinded, randomized controlled trial, we enrolled Chinese adults aged 45-75 years with self-reported constipation. Individuals were randomly assigned in a 1:1 ratio to a 1,3-dioleoyl-2-palmitoyl-glycerol (OPO)-enriched oil (66% palmitic acid in the sn-2 position) or a control vegetable oil (24% palmitic acid in the sn-2 position) daily for 24 weeks. Skim milk powder was used as the carrier for both fats. Interviews and body composition were performed at baseline, week 4, week 12 and week 24. A fasting blood draw was taken except at week 4. This study was a secondary analysis and considered exploratory. A total of 111 adults (83 women and 28 men, mean age 64.2 ± 7.0 years) were enrolled, of whom 53 were assigned to the OPO group and 57 to the control group. During the intervention, blood glucose, triglyceride, the triglyceride-glucose index, total cholesterol, low-density lipoprotein cholesterol and remnant cholesterol remained stable, while high-density lipoprotein cholesterol decreased in both groups (p = 0.003). No differences in change were observed between the groups (all p > 0.05). From baseline to week 24, the level of visceral fat increased slightly (p = 0.017), while body weight, total body water, protein, soft lean mass, fat-free mass, skeletal muscle and skeletal muscle mass index (SMI) decreased in two groups (p < 0.01). At weeks 4, 12 and 24, the SMI decreased less in the OPO group than in the control group, with a trend towards significance (p = 0.090). A 24-week daily intake of sn-2-palmitate-enriched oil had no adverse impact on fasting blood glucose, lipids and body composition compared with the control vegetable oil in Chinese adults (funded by Chinese Nutrition Society National Nutrition Science Research Grant, National Key Research and Development Program of China and Wilmar (Shanghai) Biotechnology Research & Development Center Co., Ltd.; ChiCTR1900026480).

High-fat diet enhances cell proliferation and compromises intestinal permeability in a translational canine intestinal organoid model.

BACKGROUND: Emerging evidence underscores the responsiveness of the mammalian intestine to dietary cues, notably through the involvement of LGR5 + intestinal stem cells in orchestrating responses to diet-driven signals. However, the effects of high-fat diet (HFD) on these cellular dynamics and their impact on gut integrity remain insufficiently understood. Our study aims to assess the multifaceted interactions between palmitic acid (PA), cell proliferation, and the intestinal epithelial barrier using a canine colonoid model. Canine models, due to their relevance in simulating human intestinal diseases, offer a unique platform to explore the molecular mechanisms underlying HFD derived intestinal dysfunction. RESULTS: Canine colonoids were subjected to PA exposure, a surrogate for the effects of HFD. This intervention revealed a remarkable augmentation of cell proliferative activity. Furthermore, we observed a parallel reduction in transepithelial electrical resistance (TEER), indicating altered epithelium barrier integrity. While E-cadherin exhibited consistency, ZO-1 displayed a noteworthy reduction in fluorescence intensity within the PA-exposed group. CONCLUSIONS: By employing canine intestinal organoid systems, we provide compelling insights into the impact of PA on intestinal physiology. These findings underscore the importance of considering both cell proliferative activity and epithelial integrity in comprehending the repercussions of HFDs on intestinal health. Our study contributes to a deeper understanding of the consequences of HFD on intestinal homeostasis, utilizing valuable translational in vitro models derived from dogs.

Carboxymethyl Chitosan-Coated Cyanidin-3-O-Glucoside-Beared Nanonutriosomes Suppress Palmitic Acid-Induced Hepatocytes Injury.

Cyanidin-3-O-glucoside (C3G) is classified as an anthocyanin (ACN) and is recognized for its remarkable antioxidant properties. Yet, the inadequate physicochemical stability of C3G restricts its potential for various biological applications. Thus, in this study, carboxymethyl chitosan (CMC)-coated nanonutriosomes (NS) were synthesized as a novel carrier for encapsulating C3G (CMC-C3G-NS) to improve C3G stability. CMC-C3G-NS exhibited a diameter of less than 200 nm along with an encouraging encapsulation efficiency exceeding 90%. Notably, the formulated CMC-C3G-NS possessed better stability under various pH, ionic, and oxygen conditions, improved controlled release properties, and higher hepatocellular uptake than uncoated particles (C3G-NS), indicating a longer retention time of C3G in a physiological environment. Of utmost significance, CMC-C3G-NS demonstrated superior alleviating effects against palmitic acid (PA)-induced oxidative hepatic damage compared to C3G-NS. Our study provided promising nanocarriers with the potential to deliver hydrophilic ACNs and controlled release properties for PA-induced hepatotoxicity alleviation.

Differences in Plasma Fatty Acid Composition Related to Chronic Pancreatitis: A Pilot Study.

OBJECTIVES: Chronic pancreatitis (CP) is an inflammatory disease affecting the absorption of fat-soluble nutrients. Signaling in pancreatic cells that lead to inflammation may be influenced by fatty acids (FAs) through diet and de novo lipogenesis. Here, we investigated the relationship between plasma FA composition in CP with heterogeneity of etiology and complications of CP. MATERIALS AND METHODS: Blood and clinical parameters were collected from subjects with CP (n = 47) and controls (n = 22). Plasma was analyzed for FA composition using gas chromatography and compared between controls and CP and within CP. RESULTS: Palmitic acid increased, and linoleic acid decreased in CP compared with controls. Correlations between age or body mass index and FAs are altered in CP compared with controls. Diabetes, pancreatic calcifications, and substance usage, but not exocrine pancreatic dysfunction, were associated with differences in oleic acid and linoleic acid relative abundance in CP. De novo lipogenesis index was increased in the plasma of subjects with CP compared with controls and in calcific CP compared with noncalcific CP. CONCLUSIONS: Fatty acids that are markers of de novo lipogenesis and linoleic acid are dysregulated in CP depending on the etiology or complication. These results enhance our understanding of CP and highlight potential pathways targeting FAs for treating CP.

2-Bromopalmitate depletes lipid droplets to inhibit viral replication.

The global impact of emerging viral infections emphasizes the urgent need for effective broad-spectrum antivirals. The cellular organelle, lipid droplet (LD), is utilized by many types of viruses for replication, but its reduction does not affect cell survival. Therefore, LD is a potential target for developing broad-spectrum antivirals. In this study, we found that 2-bromopalmitate (2 BP), a previously defined palmitoylation inhibitor, depletes LD across all studied cell lines and exerts remarkable antiviral effects on different coronaviruses. We comprehensively utilized 2 BP, alongside other palmitoylation inhibitors such as cerulenin and 2-fluoro palmitic acid (2-FPA), as well as the enhancer palmostatin B and evaluated their impact on LD and the replication of human coronaviruses (hCoV-229E, hCoV-Oc43) and murine hepatitis virus (MHV-A59) at non-cytotoxic concentrations. While cerulenin and 2-FPA exhibited moderate inhibition of viral replication, 2 BP exhibited a much stronger suppressive effect on MHV-A59 replication, although they share similar inhibitory effects on palmitoylation. As expected, palmostatin B significantly enhanced viral replication, it failed to rescue the inhibitory effects of 2 BP, whereas it effectively counteracted the effects of cerulenin and 2-FPA. This suggests that the mechanism that 2 BP used to inhibit viral replication is beyond palmitoylation inhibition. Further investigations unveil that 2 BP uniquely depletes LDs, a phenomenon not exhibited by 2-FPA and cerulenin. Importantly, the depletion of LDs was closely associated with the inhibition of viral replication because the addition of oleic acid to 2 BP significantly rescued LD depletion and its inhibitory effects on MHV-A59. Our findings indicate that the inhibitory effects of 2 BP on viral replication primarily stem from LD disruption rather than palmitoylation inhibition. Intriguingly, fatty acid (FA) assays demonstrated that 2 BP reduces the FA level in mitochondria while concurrently increasing FA levels in the cytoplasm. These results highlight the crucial role of LDs in viral replication and uncover a novel biological activity of 2 BP. These insights contribute to the development of broad-spectrum antiviral strategies. IMPORTANCE: In our study, we conducted a comparative investigation into the antiviral effects of palmitoylation inhibitors including 2-bromopalmitate (2-BP), 2-fluoro palmitic acid (2-FPA), and cerulenin. Surprisingly, we discovered that 2-BP has superior inhibitory effects on viral replication compared to 2-FPA and cerulenin. However, their inhibitory effects on palmitoylation were the same. Intrigued by this finding, we delved deeper into the underlying mechanism of 2-BP's potent antiviral activity, and we unveiled a novel biological activity of 2-BP: depletion of lipid droplets (LDs). Importantly, we also highlighted the crucial role of LDs in viral replication. Our insights shed new light on the antiviral mechanism of LD depletion paving the way for the development of broad-spectrum antiviral strategies by targeting LDs.

Sex-specific vulnerabilities in human astrocytes underpin the differential impact of palmitic acid.

Obesity and neurometabolic diseases have been linked to neurodegenerative diseases. Our hypothesis is that the endogenous estrogenic component of human astrocytes plays a critical role in cell response during lipotoxic damage, given that obesity can disrupt hormonal homeostasis and cause brain inflammation. Our findings showed that high concentrations of palmitic acid (PA) significantly reduced cell viability more in male astrocytes, indicating sex-specific vulnerabilities. PA induced a greater increase in cytosolic reactive oxygen species (ROS) production in males, while female astrocytes exhibited higher superoxide ion levels in mitochondria. In addition, female astrocytes treated with PA showed increased expression of antioxidant proteins, including catalase, Gpx-1 and Nrf2 suggesting a stronger cellular defence mechanism. Interestingly, there was a difference in the expression of estrogenic components, such as estrogen, androgens, and progesterone receptors, as well as aromatase and 5α-reductase enzymes, between males and females. PA induced their expression mainly in females, indicating a potential protective mechanism mediated by endogenous hormones. In summary, our findings highlight the impact of sex on the response of human astrocytes to lipotoxicity. Male astrocytes appear to be more susceptible to cellular damage when exposed to high concentrations of fatty acids.

Dihydromyricetin ameliorates hepatic steatosis and insulin resistance via AMPK/PGC-1α and PPARα-mediated autophagy pathway.

BACKGROUND: Dihydromyricetin (DHM), a flavonoid compound of natural origin, has been identified in high concentrations in ampelopsis grossedentata and has a broad spectrum of biological and pharmacological functions, particularly in regulating glucose and lipid metabolism. The objective of this research was to examine how DHM affected nonalcoholic fatty liver disease (NAFLD) and its underlying mechanisms involved in the progression of NAFLD in a rat model subjected to a high-fat diet (HFD). Additionally, the study examines the underlying mechanisms in a cellular model of steatohepatitis using palmitic acid (PA)-treated HepG2 cells, with a focus on the potential correlation between autophagy and hepatic insulin resistance (IR) in the progress of NAFLD. METHODS: SD rats were exposed to a HFD for a period of eight weeks, followed by a treatment with DHM (at doses of 50, 100, and 200 mg·kg-1·d-1) for additional six weeks. The HepG2 cells received a 0.5 mM PA treatment for 24 h, either alone or in conjunction with DHM (10 µM). The histopathological alterations were assessed by the use of Hematoxylin-eosin (H&E) staining. The quantification of glycogen content and lipid buildup in the liver was conducted by the use of PAS and Oil Red O staining techniques. Serum lipid and liver enzyme levels were also measured. Autophagic vesicle and autolysosome morphology was studied using electron microscopy. RT-qPCR and/or western blotting techniques were used to measure IR- and autophagy-related factors levels. RESULTS: The administration of DHM demonstrated efficacy in ameliorating hepatic steatosis, as seen in both in vivo and in vitro experimental models. Moreover, DHM administration significantly increased GLUT2 expression, decreased G6Pase and PEPCK expression, and improved IR in the hepatic tissue of rats fed a HFD and in cells exhibiting steatosis. DHM treatment elevated Beclin 1, ATG 5, and LC3-II levels in hepatic steatosis models, correlating with autolysosome formation. The expression of AMPK levels and its downstream target PGC-1α, and PPARα were decreased in HFD-fed rats and PA-treated hepatocytes, which were reversed through DHM treatment. AMPK/ PGC-1α and PPARα knockdown reduced the impact of DHM on hepatic autophagy, IR and accumulation of hepatic lipid. CONCLUSIONS: Our findings revealed that AMPK/ PGC-1α, PPARα-dependent autophagy pathways in the pathophysiology of IR and hepatic steatosis has been shown, suggesting that DHM might potentially serve as a promising treatment option for addressing this disease.

FGF19 Promotes the Proliferation and Insulin Secretion from Human Pancreatic ß Cells Via the IRS1/GLUT4 Pathway.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is a commonly observed complication associated with obesity. The effect of fibroblast growth factor 19 (FGF19), a promising therapeutic agent for metabolic disorders, on pancreatic ß cells in obesity-associated T2DM remains poorly understood. METHODS: Human pancreatic ß cells were cultured with high glucose (HG) and palmitic acid (PA), followed by treatment with FGF19. The cell proliferation, apoptosis, and insulin secretion were evaluated by CCK-8, qRT-PCR, ELISA, flow cytometry, and western blotting. The expression of the insulin receptor substrate (IRS)/glucose transporter (GLUT) pathway was evaluated. The interaction between FGF19 and IRS1 was predicted using the STRING database and verified by co-immunoprecipitation and immunofluorescence. The regulatory effects of the IRS1/GLUT4 pathway on human pancreatic ß cells were assessed by overexpressing IRS1 and silencing IRS1 and GLUT4. RESULTS: HG+PA treatment reduced the human pancreatic ß cell proliferation and insulin secretion and promoted cell apoptosis. However, FGF19 treatment restored these alterations and significantly increased the expressions of IRS1, GLUT1, and GLUT4 in the IRS/GLUT pathway. Furthermore, FGF19 and IRS1 were found to interact. IRS1 overexpression partially promoted the proliferation of pancreatic ß cells and insulin secretion through GLUT4. Additionally, the silencing of IRS1 or GLUT4 attenuated the therapeutic effects of FGF19. CONCLUSION: In conclusion, FGF19 partly promoted the proliferation and insulin secretion of human pancreatic ß cells and inhibited apoptosis by upregulating the IRS1/GLUT4 pathway. These findings establish a theoretical framework for the clinical utilization of FGF19 in the treatment of obesity-associated T2DM.

Creation of an Atherosclerosis Model Using Palmitic Acid and Oleic Acid in the Vascular Smooth Muscle Cells of Rats.

BACKGROUND: Atherosclerosis (AS) is a chronic vascular inflammatory disease resulting from vascular endothelial injury and lipid deposition, closely linked to abnormal lipid metabolism within the body. The critical processes involved in atherosclerosis encompass lipid deposition, oxidation, metabolic disruptions, and inflammatory stimulation within the inner vessel wall. Lipid deposition emerges as a pivotal factor triggering these pathological changes, with vascular smooth muscle cells (VSMCs) playing a significant role in the development of AS. Therefore, the goal was to employ lipids, specifically palmitic acid (PA) and oleic acid (OA) solutions, to stimulate VSMCs and create an in vitro atherosclerosis model. This approach allows for the establishment of a rapid and efficient cell model for simulating atherosclerosis in vitro. METHODS: Primary vascular smooth muscle cells (VSMCs) were isolated and cultured from the thoracic aorta of healthy rats using the tissue-block method. VSMCs were identified through cell climbing slices and immunofluorescence. The growth of VSMCs was observed using light microscopy. The logarithmic growth phase of VSMCs was induced and stimulated by various concentrations of palmitic acid (PA) and oleic acid (OA) ranging from 0 to 650 µmol/L, with a gradient dilution of 50 µmol/L. VSMC activity was assessed using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Intracellular lipid deposition was visualized through Oil Red O staining. The levels of total cholesterol (TC), triglyceride (TG), high-density lipoprotein-cholesterol (HDL-C), and low-density lipoprotein-cholesterol (LDL-C) within VSMCs were quantified using commercially available kits. RESULTS: The optimal conditions for VSMC proliferation were determined to be an OA concentration of 500 µmol/L, a PA concentration of 300 µmol/L, and a culture duration of 48 hours. In comparison to the control group, the presence of lipid droplets within VSMCs became significantly evident following treatment with OA or PA. Furthermore, the levels of TC, TG, and LDL-C increased, while the HDL-C content decreased after treatment with OA or PA. CONCLUSIONS: A research model for atherosclerosis (AS) and the early stages of cardiovascular events, specifically lipid deposition, was successfully established through the use of OA and PA solutions. This model has the potential to open up new research avenues for gaining a deeper understanding of the pathogenesis and progression of AS.

Comparison of the effects of monounsaturated fatty acids and polyunsaturated fatty acids on the lipotoxicity of islets.

Background: Monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) have been reported to combat saturated fatty acid (SFA)-induced cellular damage, however, their clinical effects on patients with metabolic diseases such as diabetes and hyperlipidemia are still controversial. Since comparative studies of the effects of these two types of unsaturated fatty acids (UFAs) are still limited. In this study, we aimed to compare the protective effects of various UFAs on pancreatic islets under the stress of SFA-induced metabolic disorder and lipotoxicity. Methods: Rat insulinoma cell line INS-1E were treated with palmitic acid (PA) with or without UFAs including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA), and oleic acid (OA) to determine cell viability, apoptosis, endoplasmic reticulum (ER) stress, and inflammatory. In vivo, male C57BL/6 mice were fed a 60% high-fat diet (HFD) for 12 w. Then the lard in HFD was partially replaced with fish oil (FO) and olive oil (OO) at low or high proportions of energy (5% or 20%) to observe the ameliorative effects of the UFA supplement. Results: All UFAs significantly improved PA-induced cell viability impairment in INS-1E cells, and their alleviation on PA induced apoptosis, ER stress and inflammation were confirmed. Particularly, OA had better effects than EPA, DHA, and AA on attenuating cellular ER stress. In vivo, the diets with a low proportion of UFAs (5% of energy) had limited effects on HFD induced metabolic disorder, except for a slight improved intraperitoneal glucose tolerance in obese mice. However, when fed diets containing a high proportion of UFAs (20% of energy), both the FO and OO groups exhibited substantially improved glucose and lipid metabolism, such as decrease in total cholesterol (TC), low-density lipoprotein (LDL), fasting blood glucose (FBG), and fasting blood insulin (FBI)) and improvement of insulin sensitivity evidenced by intraperitoneal glucose tolerance test (IPGTT) and intraperitoneal insulin tolerance test (IPITT). Unexpectedly, FO resulted in abnormal elevation of the liver function index aspartate aminotransferase (AST) in serum. Pathologically, OO attenuated HFD-induced compensatory hyperplasia of pancreatic islets, while this effect was not obvious in the FO group. Conclusions: Both MUFAs and PUFAs can effectively protect islet ß cells from SFA-induced cellular lipotoxicity. In particular, both OA in vitro and OO in vivo showed superior activities on protecting islets function and enhance insulin sensitivity, suggesting that MUFAs might have greater potential for nutritional intervention on diabetes.