Hepatoprotective effects of sea cucumber ether-phospholipids against alcohol-induced lipid metabolic dysregulation and oxidative stress in mice

Effects of mitochondrial lipidome alterations on quality deterioration of Larimichthys crocea postmortem storage: New insight from the perspective of mediating mitochondria-dependent apoptosis

Apoptosis occurs in the myocyte of fish postmortem storage. Based on the important role of mitochondrial lipid molecules in regulating apoptosis, the study aims to investigate the potential impact of mitochondrial lipids on apoptosis and quality deterioration of large yellow croaker. A total of 1079 lipid molecule species in 13 classes were identified in mitochondria. PC and PE decreased by 17.40 % and 28.31 % at 24 h, which induces mitochondrial damage and induces oxidative stress. Cytochrome c induced CL oxidation mediated by ROS (Oxidized CL increased by 30.65 %), resulting in cytochrome c release and activates caspase-3. The cytochrome c of cytoplasm and caspase-3 activity increased by 79.32 % and 82.72 % from 0 to 24 h, which led to significant apoptosis. Accumulation of ROS and activated caspase-3 during apoptosis induced muscle oxidation and softening. These findings provide new insights into the relationship between mitochondrial lipid changes and apoptosis and quality deterioration in fish postmortem storage.

Plasmalogens Reversed Oxidative Stress and Inflammatory Response Exacerbated by Damage to Cell Membrane Properties in Acute Liver Injury

BACKGROUND

In acute liver injury (ALI), cell membrane damage could induce an inflammatory response and oxidative stress. As a membrane glycerophospholipid, plasmalogens (PLS) are crucial in regulating the cell membrane properties and exhibit beneficial effects in various liver diseases. However, the specific regulatory effects of PLS in the ALI remain unknown.

METHODS

We utilized CCl4 to induce ALI in AML12 hepatocytes and C57BL/6J mice and examined oxidative stress indicators and inflammatory cytokine levels. Our study further validated the effect of PLS on cell membrane integrity by Lactate Dehydrogenase (LDH) release assay and Dil/Calcein assay, and molecular dynamics (MD) simulations were employed to elucidate the molecular mechanisms by which PLS affected cell membranes.

RESULTS

PLS attenuated hepatocyte damage both in vivo and in vitro. Moreover, PLS increased levels of SOD, GSH, and CAT and inhibited the production of malondialdehyde. PLS succeeded in decreasing proinflammatory cytokines (TNF-α, IL-1β, and IL-6) while increasing anti-inflammatory cytokines (IL-10). Furthermore, PLS effectively maintained the cell membrane integrity. The MD simulations well explained the molecular mechanisms: a high level of PLS modulated the cell membrane properties, enabling them to be more flexible, elastic, and less prone to rupture.

CONCLUSIONS

Our study illustrated the effect and molecular mechanisms of PLS against ALI, potentially broadening its application in liver diseases.

ASPP2 deficiency attenuates lipid accumulation through the PPARγ pathway in alcoholic liver injury

The initial stage of alcoholic liver disease (ALD) is hepatic steatosis. Recent studies have highlighted a possible role for Apoptosis-stimulating protein 2 of p53 (ASPP2) in regulating hepatic lipid metabolism in nonalcoholic fatty liver (NAFLD). However, whether ASPP2 regulates alcohol-induced lipid accumulation and its mechanisms remain unclear. To explore that, we establish an alcoholic liver injury model in vivo and in vitro. The clinical specimens were collected from liver tissues of patients with alcoholic liver disease. Lipid metabolism was detected by HE staining, oil red O staining and qPCR; and ASPP2-peroxisome proliferator-activated receptor γ (PPARγ) signaling pathways were detected by western blot and immunohistochemical staining. We found that both ASPP2 and PPARγ expression increased in patients and mouse models with ALD. We also discovered the reduction of ASPP2 significantly inhibited the expression of PPARγ and alleviated alcohol-induced hepatic lipid accumulation and liver injury in vivo and in vitro. Mechanistically, the PPARγ agonist reversed the protective effect of ASPP2 downregulation on hepatic steatosis and liver injury, while the opposite results were observed using PPARγ inhibitor. In conclusion, ASPP2 exacerbates ethanol-induced lipid accumulation and hepatic injury by upregulating the PPARγ signaling pathway, thus promoting the occurrence and development of ALD.

Combined UPLC-QqQ-MS/MS and AP-MALDI Mass Spectrometry Imaging Method for Phospholipidomics in Obese Mouse Kidneys: Alleviation by Feeding Sea Cucumber Phospholipids

Sea cucumber phospholipids have ameliorative effects on various diseases related to lipid metabolism. However, it is unclear whether it can ameliorate obesity-associated glomerulopathy (ORG) induced by a high-fat diet (HFD). The present study applied UPLC-QqQ-MS/MS and atmospheric pressure matrix-assisted laser desorption ionization mass spectrometry imaging (AP-MALDI MSI) to investigate the effects of sea cucumber phospholipids, including plasmalogen PlsEtn and plasmanylcholine PakCho, on phospholipid profiles in the HFD-induced ORG mouse kidney. Quantitative analysis of 135 phospholipids revealed that PlsEtn and PakCho significantly modulated phospholipid levels. Notably, PlsEtn modulated kidney overall phospholipids better than PakCho. Imaging the "space-content" of 9 phospholipids indicated that HFD significantly increased phospholipid content within the renal cortex. Furthermore, PlsEtn and PakCho significantly decreased the expression of transport-related proteins CD36, while elevating the expression of fatty acid β-oxidation-related protein PPAR-α in the renal cortex. In conclusion, sea cucumber phospholipids reduced renal lipid accumulation, ameliorated renal damage, effectively regulated the content and distribution of renal phospholipids, and improved phospholipid homeostasis, exerting an anti-OGR effect.

Sea cucumber plasmalogen enhance lipophagy to alleviate abnormal lipid accumulation induced by high-fat diet

Sea cucumber phospholipids, including the plasmalogen (PlsEtn) and plasmanylcholine (PakCho), have been shown to play a regulatory role in lipid metabolism disorders, but their mechanism of action remains unclear. Therefore, high-fat diet (HFD) and palmitic acid were used to establish lipid accumulation models in mice and HepG2 cells, respectively. Results showed that PlsEtn can reduce lipid deposition both in vivo and in vitro. HFD stimulation abnormally activated lipophagy through the phosphorylation of the AMPK/ULK1 pathway. The lipophagy flux monitor revealed abnormalities in the fusion stage of lipophagy. Of note, only PlsEtn stimulated the dynamic remodeling of the autophagosome membrane, which was indicated by the significantly decreased LC3 II/I ratio and p62 level. In all experiments, the effect of PlsEtn was significantly higher than that of PakCho. These findings elucidated the mechanism of PlsEtn in alleviating lipid accumulation, showed that it might be a lipophagy enhancer, and provided new insights into the high-value utilization of sea cucumber as an agricultural resource.

Sea Cucumber Plasmalogen Regulates the Lipid Profile in High-Fat Diet Mouse Liver via Lipophagy

The sea cucumber plasmalogen PlsEtn has been shown to be associated with various chronic diseases related to lipid metabolism. However, the mechanism is unclear. Therefore, the present study used the sea cucumber plasmanylcholine PakCho as a structural contrast to PlsEtn and assessed its effect in 8 week high-fat diet (HFD)-fed mice. The lipidomic approach based on high-resolution mass spectrometry combined with molecular biology techniques was used to evaluate the mechanism of PlsEtn. The results showed that both PlsEtn and PakCho significantly inhibited an increase in mouse body weight and liver total triglyceride and total cholesterol levels caused by HFD. In addition, oil red O staining demonstrated that lipid droplets stored in the liver were degraded. Meanwhile, untargeted lipidomic experiments revealed that total lipids (increased by 42.8 mmol/mg prot; p < 0.05), triglycerides (increased by 38.9 mmol/mg prot; p < 0.01), sphingolipids (increased by 1.5 mmol/mg prot; p < 0.0001), and phospholipids (increased by 2.5 mmol/mg prot; p < 0.05) were all significantly elevated under HFD. PlsEtn resolved lipid metabolism disorders by alleviating the abnormal expression of lipid subclasses. In addition, five lipid molecular species, PE (18:1/20:4), PE (18:1/20:3), PE (18:1/18:3), TG (16:0/16:0/17:0), and TG (15:0/16:0/18:1), were identified as the biomarkers of HFD-induced lipid metabolism disorders. Finally, lipophagy-associated protein expression analysis showed that HFD abnormally activated lipophagy via ULK1 phosphorylation and PlsEtn alleviated lipophagy disorder through lysosomal function promotion. In addition, PlsEtn performed better than PakCho. Taken together, the current study results unraveled the mechanism of PlsEtn in alleviating lipid metabolism disorder and offered a new theoretical foundation for the high-value development of sea cucumber.

The Role of Oxidative Stress in Alcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis of Preclinical Studies

Alcoholic Fatty Liver Disease (AFLD) is characterized by the accumulation of lipids in liver cells owing to the metabolism of ethanol. This process leads to a decrease in the NAD+/NADH ratio and the generation of reactive oxygen species. A systematic review and meta-analysis were conducted to investigate the role of oxidative stress in AFLD. A total of 201 eligible manuscripts were included, which revealed that animals with AFLD exhibited elevated expression of CYP2E1, decreased enzymatic activity of antioxidant enzymes, and reduced levels of the transcription factor Nrf2, which plays a pivotal role in the synthesis of antioxidant enzymes. Furthermore, animals with AFLD exhibited increased levels of lipid peroxidation markers and carbonylated proteins, collectively contributing to a weakened antioxidant defense and increased oxidative damage. The liver damage in AFLD was supported by significantly higher activity of alanine and aspartate aminotransferase enzymes. Moreover, animals with AFLD had increased levels of triacylglycerol in the serum and liver, likely due to reduced fatty acid metabolism caused by decreased PPAR-α expression, which is responsible for fatty acid oxidation, and increased expression of SREBP-1c, which is involved in fatty acid synthesis. With regard to inflammation, animals with AFLD exhibited elevated levels of pro-inflammatory cytokines, including TNF-a, IL-1β, and IL-6. The heightened oxidative stress, along with inflammation, led to an upregulation of cell death markers, such as caspase-3, and an increased Bax/Bcl-2 ratio. Overall, the findings of the review and meta-analysis indicate that ethanol metabolism reduces important markers of antioxidant defense while increasing inflammatory and apoptotic markers, thereby contributing to the development of AFLD.

A functional chicken-liver hydrolysate-based supplement ameliorates alcohol liver disease via regulation of antioxidation, anti-inflammation, and antiapoptosis

Tons of broiler livers are produced yearly in Taiwan but always considered waste. Our team has successfully patented and characterized a chicken-liver hydrolysate (CLH) with several biofunctions. Chronic alcohol consumption causes hepatosteatosis or even hepatitis, cirrhosis, and cancers. This study was to investigate the hepatoprotection of CLH-based supplement (GBHP01™) against chronic alcohol consumption. Results showed that GBHP01™ could reduce (p < .05) enlarged liver size, lipid accumulation/steatosis scores, and higher serum AST, ALT, γ-GT, triglyceride, and cholesterol levels induced by an alcoholic liquid diet. GBHP01™ reduced liver inflammation and apoptosis in alcoholic liquid-diet-fed mice via decreasing TBARS, interleukin-6, interleukin-1β, and tumor necrosis factor-α levels, increasing reduced GSH/TEAC levels and activities of SOD, CAT and GPx, as well as downregulating CYP2E1, BAX/BCL2, Cleaved CASPASE-9/Total CASPASE-9 and Active CASPASE-3/Pro-CASPASE-3 (p < .05). Furthermore, GBHP01™ elevated hepatic alcohol metabolism (ADH and ALDH activities) (p < .05). In conclusion, this study prove the hepatoprotection of GBHP01™ against alcohol consumption.

Antioxidants ameliorate oxidative stress in alcoholic liver injury by modulating lipid metabolism and phospholipid homeostasis

Alcoholic liver disease (ALD) is a significant risk factor in the global disease burden. The antioxidants vitamin C (Vc) and N-acetyl cysteine (NAC) have shown hepatoprotective effects in preventing and treating ALD. However, the correlation between the improved effect of antioxidants and lipid metabolism is still unclear. In this study, AML12 cells and C57BL/6 mice stimulated with alcohol were used to investigate the protective effects and potential mechanisms of two antioxidants (Vc and NAC) on alcoholic liver injury. Results showed that Vc and NAC attenuated intracellular lipid accumulation and oxidative damage induced by excessive alcohol exposure in hepatic AML12 cells. The in vivo results indicated that antioxidants ameliorated alcohol-induced changes in histopathology, reducing the levels of alcohol metabolizing factors and aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglyceride (TG), and total cholesterol (TC) contents, which demonstrated that antioxidants effectively mitigated liver injury in ALD mice. Further studies showed that antioxidants reversed the disruption of fatty acid (FA) synthesis and lipid transport induced by alcohol exposure, and restored phospholipid levels. Especially, Vc and NAC increased the endogenous antioxidant plasmenyl phosphatidylethanolamine (PlsEtn). Additionally, antioxidants ameliorated the alcohol-impaired mitochondrial function and inhibited excessive oxidative stress. In conclusion, antioxidants can regulate lipid metabolism and phospholipid homeostasis, which in turn inhibit oxidative stress and thereby exert protective effects against ALD.

Sea Cucumber Phospholipids Regulate Cholesterol Metabolism in High-Fat Diet-induced ApoE-/- Mice

BACKGROUND

Sea cucumber phospholipids, marine-derived lipids with high nutritional functions, have been proven to exhibit various biological activities. However, it is unclear how sea cucumber phospholipids regulate cholesterol (Chol) metabolism in atherosclerosis (AS).

OBJECTIVE

This study aimed to investigate the effects and mechanism of sea cucumber phospholipids on the metabolism of Chol and cholesterol esters (CE) in ApoE^-/- mice, including plasmenyl phosphatidylethanolamine (PE-P) and plasmanyl phosphatidylcholine (PC-O).

METHODS

Male ApoE^-/- mice were fed with chow diet, high-fat diet (HFD), and high-fat diet supplemented with PC-O or PE-P, respectively. We integrated a targeted lipidomics strategy to classify and compare the cholesteryl esters according to their fatty acid types, then analyzed the individual cholesteryl ester molecular species in the liver and serum of mice. Furthermore, the Chol metabolism-related genes and pathways were analyzed in high-fat-induced ApoE^-/- mice.

RESULTS

Biochemical analysis showed that sea cucumber phospholipids significantly inhibit the generation of arterial plaque in ApoE^-/- mice. Compared with the HFD group, PE-P significantly reduced the contents of saturated fatty acid-cholesterol esters (SFA-CE) and monounsaturated fatty acid-cholesterol esters (MUFA-CE) in mice liver (P < 0.05), whereas PC-O particularly upregulated CE20:5 and CE22:6 in serum of mice (P < 0.001). Furthermore, PC-O and PE-P inhibited the Chol synthesis pathway (Cyp7A1 and Cyp27A1), as well as promoted the catabolism of Chol by upregulating gene expressions of bile acid synthesis (Abcb11) and lysosomal activity (Lamp1), respectively.

CONCLUSIONS

Sea cucumber phospholipids could ameliorate the AS symptoms by regulating Chol metabolism.

Salecan confers anti-inflammatory effects in liver injury via regulating gut microbiota and its metabolites

Salecan, a natural β-glucan and one of the novel food ingredients approved in China, has been shown a variety of positive health effects, yet the mechanism of liver injury remains poorly understood. In addition, β-glucan could induce the shifts in gut microbiota, however, whether modulation of gut microbiota by β-glucan is associated with their positive health effects remain elusive. Here, the anti-inflammatory effects and the underlying mechanism of Salecan supplementation in CCl4-induced liver injury were investigated. After 8 weeks of treatment, we observed that Salecan alleviated liver injury by regulating inflammatory response and M2 macrophage polarization. In addition, Salecan treatment modulated the composition of gut microbiota and antibiotic cocktail treatment indicated that the hepatoprotective effect of Salecan was dependent on the gut microbiota. Fecal microbiota transplantation was used to further verify the mechanism, and we confirmed that microbial colonization partially alleviated liver injury. Besides, microbiota-derived metabolites of Salecan also contributed to the hepatoprotective and anti-inflammatory effect of Salecan against liver injury. These findings supported that Salecan intervention attenuated liver injury by regulating gut microbiota and its metabolites.

Sea cucumber-derived compounds for treatment of dyslipidemia: A review

Dyslipidemias are disorders of plasma levels of lipids, such as elevated levels of total cholesterol and triglyceride, that are associated with various human diseases including cardiovascular disease (CVD) and non-alcoholic fatty liver disease (NAFLD). Statins are the first-line drugs for treatment of dyslipidemia. However, a substantial proportion of patients cannot reach the recommended LDL-c level even with the highest tolerated doses of statins, and there is no available drug specifically for NAFLD therapy. Sea cucumbers are one of the widely distributed invertebrates, and are an important resource of food and medicine. Sea cucumbers have many valuable nutrients including saponins, fatty acids, phospholipids, cerebrosides, sulfated polysaccharides, as well as proteins and peptides. In recent years, these natural products derived from sea cucumbers have attracted attentions for treatment of CVD and NAFLD because of their lipid-lowering effect and low toxicity. However, the hypolipidemic mechanisms of action and the structure-activity relationship of these bioactive components have not been well-documented in literature. This review article summarizes the signaling pathways and the potential structure-activity relationship of sea cucumber-derived bioactive compounds including saponins, lipids, carbohydrates as well as peptides and proteins. This article will provide information useful for the development of sea cucumber-derived lipid-lowering compounds as well as for investigation of hypolipidemic compounds that are derived from other natural resources.

Salecan ameliorates liver injury by regulating gut microbiota and its metabolites

Salecan ameliorates liver injury by regulating oxidative stress and the gut microbiota.