Journal of Lipid Research最新文献

Lipid nanoparticles (LNPs) are a powerful technology for delivering nucleic acids into cells and have greatly contributed to the development of severe acute respiratory syndrome coronavirus 2 mRNA vaccines and nucleic acid-based therapeutics. However, side effects such as pain and swelling at the injection site have been reported after vaccination with severe acute respiratory syndrome coronavirus 2 mRNA, and these are thought to be partly due to LNP-induced inflammation. In this study, we focused on an anti-inflammatory metabolite derived from omega-3 fatty acids and investigated whether it could suppress LNP-induced inflammatory side effects associated with mRNA-LNP vaccination. Intramuscular injection of empty LNPs lacking mRNA elicited inflammatory responses in mice comparable to those induced by mRNA-LNPs. Moreover, neutrophil depletion with an antibody demonstrated that neutrophils are key effector cells in LNP-induced inflammation. To suppress this response, we focused on 17,18-epoxyeicosatetraenoic acid (17,18-EpETE), an omega-3 fatty acid metabolite known to target neutrophils. Intramuscular co-injection of empty LNPs and 17,18-EpETE significantly reduced local swelling and infiltration of immune cells, including neutrophils, at the injection site. Further analysis revealed that this anti-inflammatory effect of 17,18-EpETE was mediated via G protein-coupled receptor 40. Importantly, 17,18-EpETE did not impair antibody production elicited by mRNA-LNP vaccination. These findings suggest that 17,18-EpETE has potential as a supplementary agent to mitigate inflammatory side effects without compromising the immunogenic efficacy of mRNA-LNP vaccines.

Glycosphingolipids are essential lipids enriched in the outer leaflet of the plasma membrane, particularly those forming the myelin sheaths. Disorders impacting the glycosphingolipid metabolism cause devastating demyelinating diseases. We extend this observation by investigating the brain topographic pattern of the progressive accumulation of these glycosphingolipids throughout the lifespan of the murine model, correlating with alterations in myelin markers and astrogliosis. The reported IMS approach reveals disturbances in the brain glycosphingolipid spatial distribution and abundance, which is of utmost importance when examining the impact of neurotherapeutics targeting these cytotoxically elevated sphingolipids. Similar approaches can be applied to other sphingolipid-neurodegenerative disorders. The development of a novel imaging mass spectrometry (IMS) method provides key information on the spatial distribution and quantification of pathogenic glycosphingolipids, hexosphingosines, and monohexosylceramides across the brain of the murine model of Krabbe disease, an inherited lysosomal deficiency of galactocerebrosidase, associated with a demyelinating disorder with a broad spectrum of age of onset.

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease characterized by lymphocytic infiltration of exocrine glands and frequent extraglandular manifestations, with pulmonary involvement being the most prevalent. However, the mechanisms underlying pulmonary involvement remain unclear, and the role of shared metabolic disturbances in disease pathogenesis is yet to be fully elucidated. Bibliometric analyses have highlighted interstitial lung disease as a key research focus in pSS. In this study, we used an experimental SS mouse model to perform pseudotargeted sphingolipidomics on the salivary glands and lungs. Sphinganine (Sa) was identified as a key metabolite through machine learning-based screening. In vivo experiments demonstrated that administration of Sa aggravated salivary gland injury and pulmonary fibrosis in the experimental SS group. Further in vitro studies revealed that Sa activates the endoplasmic reticulum stress pathway, leading to A253 cell damage and upregulation of fibrosis markers in NIH3T3 fibroblasts. Chemoproteomic analysis revealed that Sa directly binds to the nonmuscle myosin heavy chain IIA (Myh9) and promotes its expression. Pharmacological inhibition of Myh9 restored aquaporin-5 (AQP5) expression in A253 cells and reduced fibronectin and alpha-smooth muscle actin levels in NIH3T3 cells. Collectively, this study indicates that Sa, as a shared regulatory metabolite between the salivary gland and lung, appears to be implicated in the ATF6-Myh9 signaling axis and may contribute to pSS-related pulmonary injury. Nevertheless, this relationship warrants further validation in future studies. In parallel, it proposes a novel strategy for identifying common metabolic biomarkers across affected organs in autoimmune diseases.

Alterations in sphingolipid metabolism have been implicated in the pathogenesis of Parkinson's disease (PD), yet findings regarding peripheral sphingolipid changes remain inconsistent. This study aimed to elucidate the metabolic profiles of plasma ceramides and glycosphingolipids (GSLs) in patients with PD. We recruited 250 patients with PD and 250 age- and sex-matched neurologically healthy controls. Plasma ceramide and GSL species were quantified using liquid chromatography‒tandem mass spectrometry, complemented by a meta-analysis of the gene expression levels of relevant enzymes in the substantia nigra obtained from Gene Expression Omnibus. A total of 119 sphingolipids were analyzed. Significant differences in plasma sphingolipid species were observed, including increased GSLs and decreased dihydroceramides. Incorporation of 35 significantly altered sphingolipid species enabled discrimination of patients with PD from controls with an AUC of 0.80 (P < 0.0001). Notable alterations in lipid ratios were detected, with increases in the monohexosylceramide-to-ceramide ratio as well as the monosialodihexosylganglioside-to-dihexosylceramide and trihexosylceramide-to-dihexosylceramide ratios. We also observed a higher ceramide-to-dihydroceramide ratio and shifts in ceramide characteristics, reflecting changes in the ceramide synthesis pathway. Supporting these findings, meta-analysis revealed changes in the expression of relevant enzymes, including decreased expression of lysosomal hydrolases, such as β-glucocerebrosidase and α-galactosidase, reinforcing the impaired GSL degradation and alteration in ceramide synthesis observed in PD. Our results suggest that altered peripheral ceramide and GSL profiles can discriminate PD from controls. Moreover, we highlight disrupted GSL and ceramide metabolism in PD patients, emphasizing the need for further research to explore the implications of these metabolic disturbances in PD pathogenesis.

S-palmitoylation is a dynamic and reversible post-translational modification that plays crucial roles in cancer progression. Here, we found that the oncogene of metadherin (MTDH) modulates lipid metabolism and ferroptosis by its S-palmitoylation. We demonstrate that MTDH is S-palmitoylated at Cys-75 in the endoplasmic reticulum by ZDHHC1/9 and S-depalmitoylated by APT1. The flexible loop and the α-helix length in the MTDH N-terminus affect its S-palmitoylation level. In addition, metabolomics analysis found that the S-palmitoylated MTDH increases intracellular levels of triglycerides, phosphatidylethanolamines, and phosphatidylcholines. The non-S-palmitoylation form of MTDH-CS enhanced the interaction between MTDH and the ferroptosis enhancer of Acyl-CoA synthetase long-chain family member 4 (ACSL4), thereby reducing ferroptosis sensitivity in breast cancer cells.

Several oxylipins are lipid mediators derived from the oxidation of polyunsaturated fatty acids (PUFAs). The majority of oxylipins in biological samples occurs esterified in neutral lipids (nLs) and phospholipids (PLs). They are commonly quantified indirectly following alkaline hydrolysis, providing excellent sensitivity. However, the information in which lipid classes the oxylipins occur is lost. The direct analysis of oxidized lipids is currently not sensitive enough to detect all esterified oxylipins. Here, a new hydrophilic interaction liquid chromatography (HILIC)-based lipid class fractionation using solid-phase extraction (SPE) cartridges was developed, separating lipids into nLs and 4 PL fractions using a single column. Esterified oxylipins in the fractions were quantified following alkaline hydrolysis to sensitively pinpoint in which lipid classes they are bound in plasma. The fractionation was extensively characterized for different lipid extracts, demonstrating high separation efficiency and recovery using labeled standards and untargeted analysis of endogenous lipids. Esterified oxylipins in the fractions were quantitatively detected. Based on the results from two independent human plasma pools, including SRM 1950, it is shown that: hydroxy-linoleic acids and hydroxy-α-linolenic acids are preferably bound to nLs, whereas long-chain hydroxy-PUFAs and PUFAs (i.e. ARA EPA and DHA) are predominantly esterified to phospholipid classes. Supplementation of n3-PUFAs for 12 months led to an increase in EPA- and DHA-derived oxylipins in all lipid fractions, with the highest increase in hydroxy-PUFAs in nLs. This demonstrates a precursor PUFA-dependent binding of oxylipins and a direct effect of diet on esterified oxylipins in plasma.

Apolipoprotein E (APOE) plays a tissue-specific role in diet-induced obesity: brain-expressed APOE promotes obesity, while hepatic APOE appears protective. Physiological plasma APOE levels facilitate clearance of atherogenic lipoproteins; however, supraphysiological levels induce hypertriglyceridemia and impair cholesterol clearance. APOE-induced hypertriglyceridemia has been linked to its carboxyl-terminal region (amino acids 260-270), particularly residues L261, W264, F265, L268, and V269. A bioengineered APOE4 variant, APOE4mut1, where these residues are substituted with alanine, promotes cholesterol clearance without inducing hypertriglyceridemia at any level of expression. This study examined APOE4mut1 effects on adipose tissue metabolism in vivo. Wild-type (C57BL/6) and APOE4_knock-in mice were fed a Western-type diet for varying periods and infected with adenoviruses expressing APOE4 (AdAPOE4), APOE4mut1 (AdAPOE4mut1), or only the green fluorescent protein (GFP) (AdGFP). AdAPOE4mut1 infection of C57BL/6 mice fed a Western-type diet for 8 or 24 weeks stimulated brown adipose tissue (BAT) metabolism by inducing non-shivering thermogenesis and oxidative phosphorylation. In contrast, AdAPOE4 suppressed thermogenesis in this tissue. In white adipose tissue (WAT), AdAPOE4mut1 was able to stimulate thermogenesis after 24 weeks of feeding. This stimulatory effect in WAT was dominant over wild-type APOE4, since APOE4mut1 similarly enhanced mitochondrial activity in WAT of APOE4_knock-in mice. These findings suggest that amino acid residues 260-270 of APOE4 critically regulate adipose tissue metabolism, in addition to their previously reported role in APOE-induced hypertriglyceridemia. Targeted mutagenesis within this region offers a potential therapeutic strategy for addressing hypertriglyceridemia and obesity in metabolic syndrome.

Matrix metalloproteinase-12 (MMP12) is a proinflammatory macrophage-secreted protein with immunomodulatory functions that affects neutrophil infiltration, cytokine release, macrophage recruitment, and proliferation. We have previously demonstrated that the genetic deletion of MMP12 in a cardiometabolic mouse model ameliorates obesity-induced low-grade inflammation, white adipose tissue dysfunction, and atherosclerosis. Based on the various beneficial metabolic effects of MMP-12 deletion, we hypothesized that loss of MMP-12 also positively affects whole-body energy metabolism and/or brown adipose tissue (BAT) function in a cardiometabolic mouse model. To investigate the effects of MMP12 deletion on whole-body energy metabolism and/or BAT function, we used low-density lipoprotein receptor (Ldlr)/Mmp12 double knockout (DKO) fed a high-fat, sucrose- and cholesterol-enriched diet. DKO mice housed at 22°C showed increased energy expenditure and decreased BAT size and triglyceride (TG) content. Untargeted proteomic analyses revealed the upregulation of proteins and pathways related to mitochondrial function, glucose metabolism, and fatty acid oxidation in the BAT of DKO mice, whereas the abundance of proteins and pathways associated with inflammation was reduced. In addition, DKO mice exhibited reduced macrophage infiltration in BAT, with the infiltrating macrophages showing lower expression of lipid-associated marker genes. Loss of MMP12 was associated with reduced compactness and sphericity of the mitochondria in the BAT. Following an acute cold exposure, DKO mice had decreased circulating lipid concentrations, especially very low-density lipoprotein-TG and LDL-cholesterol, and increased expression of thermogenic genes. We conclude that MMP12 may play a detrimental role in whole-body energy homeostasis and thermogenesis, as it triggers macrophage infiltration, inflammation, and mitochondrial dysfunction in BAT.

Hepatocellular carcinoma (HCC) has a higher incidence in males and is a leading cause of cancer-related deaths, which lacks effective therapies and surveillance markers. Using a murine model of bile acid excess (farnesoid X receptor and small heterodimer partner double knockout, DKO), which phenocopies many aspects of HCC, including sex differences, we investigated the links between sex, bile acid metabolism, and microbial composition. Unexpectedly, the increase in the ratios of carcinogenic deoxycholic acid (DCA) was similar between DKO males with HCC and cancer-resistant DKO females. However, both taurine-conjugated and free cholic acid (CA) sharply increased in the serum of DKO males, with free-CA comprising 65% of the bile acid pool, whereas DKO female serum was mostly comprised of conjugated bile acids. Unlike such sex differences in DKO serum composition, conjugated bile acids were predominant in the hepatic BA pool irrespective of the sex or genotype, as expected. Fecal and cecal microbiota-many of which harbor bile acid transformation/deconjugation capacity-were altered in DKO mice in a sex-specific manner. Untargeted fecal metabolite analysis showed differences in bile acids, phospholipids, and oxidized fatty acids between the genotypes, with DKO females excreting more sulphated and oxidized CA than tumor-bearing DKO males. Further analysis revealed a direct correlation between unconjugated CA levels with the abundance of the microbial genus Faecalibaculum in the DKO HCC model. These findings suggest distinct sex-specific changes in cecal and fecal microbiota, and BA composition may be leveraged in combination as a potential tool for HCC surveillance.