Project description:Vernix caseosa (VC) is a protective layer that covers the skin of most human newborns. This study characterized the VC lipid mediator profile, and examined its relationship to gestational period, gender of the newborn and maternal lifestyle. VC collected at birth from 156 newborns within the ALADDIN birth cohort was analyzed and 3 different groups of lipid mediators (eicosanoids and related oxylipin analogs, endocannabinoids and sphingolipids) were screened using LC-MS/MS. A total of 54 compounds were detected in VC. A number of associations between lipid mediators and the gestational period were observed, including increases in the ceramide to sphingomyelin ratio as well as the endocannabinoids anandamide and 2-arachidonoylglycerol. Gender-specific differences in lipid mediator levels were observed for all 3 lipid classes. In addition, levels of the linoleic acid oxidation products 9(10)-epoxy-12Z-octadecenoic and 12(13)-epoxy-9Z-octadecenoic acid (EpOMEs) as well as 12,13-dihydroxy-9Z-octadecenoic acid (DiHOME) were increased in VC of children from mothers with an anthroposophic lifestyle. Accordingly, VC was found to be rich in multiple classes of bioactive lipid mediators, which evidence lifestyle, gender and gestational week dependencies. Levels of lipid mediators in VC may therefore be useful as early stage non-invasive markers of the development of the skin as a protective barrier.
Project description:Psoriasis is a chronic immune-mediated disease that represents a unique model for investigating inflammation at local and systemic levels. Bioactive lipid mediators (LMs) are potent compounds reported to play a role in the development and resolution of inflammation. Currently, it is not known to what extent these LMs are involved in psoriasis pathophysiology and related metabolic dysfunction. Here, we use targeted and untargeted liquid chromatography-tandem mass spectrometry approaches to quantify LMs in skin and peripheral blood from psoriasis patients and compared them with those of healthy individuals. Lesional psoriasis skin was abundant in arachidonic acid metabolites, as 8-, 12- and 15-hydroxyeicosatetraenoic acid, compared with adjacent nonlesional and skin from healthy individuals. Additionally, a linoleic acid-derived LM, 13-hydroxyoctadecadienoic acid, was significantly increased compared with healthy skin (607.9 ng/g vs. 5.4 ng/g, P = 0.001). These psoriasis skin differences were accompanied by plasma decreases in antioxidant markers, including glutathione, and impaired lipolysis characterized by lower concentrations of primary and secondary bile acids. In conclusion, our study shows that psoriasis skin and blood have disease-specific phenotype profiles of bioactive LMs represented by omega-6 fatty acid-oxidized derivatives. These findings provide insights into psoriasis pathophysiology that could potentially contribute to new biomarkers and therapeutics.
Project description:Based on accumulating evidence of a role of lipid signaling in many physiological and pathophysiological processes including psychiatric diseases, the present data driven analysis was designed to gather information needed to develop a prospective biomarker, using a targeted lipidomics approach covering different lipid mediators. Using unsupervised methods of data structure detection, implemented as hierarchal clustering, emergent self-organizing maps of neuronal networks, and principal component analysis, a cluster structure was found in the input data space comprising plasma concentrations of d = 35 different lipid-markers of various classes acquired in n = 94 subjects with the clinical diagnoses depression, bipolar disorder, ADHD, dementia, or in healthy controls. The structure separated patients with dementia from the other clinical groups, indicating that dementia is associated with a distinct lipid mediator plasma concentrations pattern possibly providing a basis for a future biomarker. This hypothesis was subsequently assessed using supervised machine-learning methods, implemented as random forests or principal component analysis followed by computed ABC analysis used for feature selection, and as random forests, k-nearest neighbors, support vector machines, multilayer perceptron, and naïve Bayesian classifiers to estimate whether the selected lipid mediators provide sufficient information that the diagnosis of dementia can be established at a higher accuracy than by guessing. This succeeded using a set of d = 7 markers comprising GluCerC16:0, Cer24:0, Cer20:0, Cer16:0, Cer24:1, C16 sphinganine, and LacCerC16:0, at an accuracy of 77%. By contrast, using random lipid markers reduced the diagnostic accuracy to values of 65% or less, whereas training the algorithms with randomly permuted data was followed by complete failure to diagnose dementia, emphasizing that the selected lipid mediators were display a particular pattern in this disease possibly qualifying as biomarkers.
Project description:Our previous results showed that the specialized pro-resolving mediator (SPM) Resolvin D1 (RvD1) promotes resolution of inflammation in salivary glands in non-obese diabetic (NOD)/ShiLtJ, a mouse model for Sjögren's syndrome (SS). Additionally, mice lacking the RvD1 receptor ALX/FPR2 show defective innate and adaptive immune responses in salivary glands. Particularly, ALX/FPR2 KO mice exhibit exacerbated inflammation in their salivary glands in response to systemic LPS treatment. Moreover, female ALX/FPR2 KO mice show increased autoantibody production and loss of salivary gland function with age. Together, these studies suggest that an underlying SPM dysregulation could be contributing to SS progression. Therefore, we investigated whether SPM production is altered in NOD/ShiLtJ using metabololipidomics and enzyme-linked immunosorbent assay (ELISA). Our results demonstrate that SPM levels were broadly elevated in plasma collected from NOD/ShiLtJ female mice after disease onset, whereas these drastic changes did not occur in male mice. Moreover, gene expression of enzymes involved in SPM biosynthesis were altered in submandibular glands (SMG) from NOD/ShiLtJ female mice after disease onset, with 5-LOX and 12/15-LOX being downregulated and upregulated, respectively. Despite this dysregulation, the abundances of the SPM products of these enzymes (ie, RvD1 and RvD2) were unaltered in freshly isolated SMG cells suggesting that other cell populations (eg, lymphocytes) may be responsible for the overabundance of SPMs that we observed. The elevation of SPMs noted here appeared to be sex mediated, meaning that it was observed only in one sex (females). Given that SS primarily affects females (roughly 90% of diagnosed cases), these results may provide some insights into the mechanisms underlying the observed sexual dimorphism.
Project description:ObjectivesPolyunsaturated fatty acids (PUFAs) are structural components of membrane phospholipids and precursors of oxygenated lipid mediators with diverse functions, including the control of cell growth, inflammation and tumourigenesis. However, the molecular pathways that control the availability of PUFAs for lipid mediator production are not well understood. Here, we investigated the crosstalk of three pathways in the provision of PUFAs for lipid mediator production: (i) secreted group X phospholipase A2 (GX sPLA2) and (ii) cytosolic group IVA PLA2 (cPLA2α), both mobilizing PUFAs from membrane phospholipids, and (iii) adipose triglyceride lipase (ATGL), which mediates the degradation of triacylglycerols (TAGs) stored in cytosolic lipid droplets (LDs).MethodsWe combined lipidomic and functional analyses in cancer cell line models to dissect the trafficking of PUFAs between membrane phospholipids and LDs and determine the role of these pathways in lipid mediator production, cancer cell proliferation and tumour growth in vivo.ResultsWe demonstrate that lipid mediator production strongly depends on TAG turnover. GX sPLA2 directs ω-3 and ω-6 PUFAs from membrane phospholipids into TAG stores, whereas ATGL is required for their entry into lipid mediator biosynthetic pathways. ATGL controls the release of PUFAs from LD stores and their conversion into cyclooxygenase- and lipoxygenase-derived lipid mediators under conditions of nutrient sufficiency and during serum starvation. In starving cells, ATGL also promotes the incorporation of LD-derived PUFAs into phospholipids, representing substrates for cPLA2α. Furthermore, we demonstrate that the built-up of TAG stores by acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is required for the production of mitogenic lipid signals that promote cancer cell proliferation and tumour growth.ConclusionThis study shifts the paradigm of PLA2-driven lipid mediator signalling and identifies LDs as central lipid mediator production hubs. Targeting DGAT1-mediated LD biogenesis is a promising strategy to restrict lipid mediator production and tumour growth.
Project description:Ceramides (Cers) with ultralong (∼32-carbon) chains and ω-esterified linoleic acid, composing a subclass called omega-O-acylceramides (acylCers), are indispensable components of the skin barrier. Normal barriers typically contain acylCer concentrations of ∼10 mol%; diminished concentrations, along with altered or missing long periodicity lamellar phase (LPP), and increased permeability accompany an array of skin disorders, including atopic dermatitis, psoriasis, and ichthyoses. We developed model membranes to investigate the effects of the acylCer structure and concentration on skin lipid organization and permeability. The model membrane systems contained six to nine Cer subclasses as well as fatty acids, cholesterol, and cholesterol sulfate; acylCer content-namely, acylCers containing sphingosine (Cer EOS), dihydrosphingosine (Cer EOdS), and phytosphingosine (Cer EOP) ranged from zero to 30 mol%. Systems with normal physiologic concentrations of acylCer mixture mimicked the permeability and nanostructure of human skin lipids (with regard to LPP, chain order, and lateral packing). The models also showed that the sphingoid base in acylCer significantly affects the membrane architecture and permeability and that Cer EOP, notably, is a weaker barrier component than Cer EOS and Cer EOdS. Membranes with diminished or missing acylCers displayed some of the hallmarks of diseased skin lipid barriers (i.e., lack of LPP, less ordered lipids, less orthorhombic chain packing, and increased permeability). These results could inform the rational design of new and improved strategies for the barrier-targeted treatment of skin diseases.
Project description:Efavirenz-based antiretroviral therapy (ART) has been associated with dyslipidemia and dysglycemia, risk factors for cardiovascular disease. However, the pathogenesis is not well understood. We characterized relationships between plasma efavirenz concentrations and lipid and glucose concentrations in HIV-infected South Africans.Participants on efavirenz-based ART were enrolled into a cross-sectional study. The oral glucose tolerance test was performed after an overnight fast, and plasma drawn for mid-dosing interval efavirenz, fasting total cholesterol, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, and triglycerides concentrations.Among 106 participants (77 women), median age was 38 years, median CD4 + T-cell count was 322 cells/μL, median duration on ART was 18 months, and median (interquartile range) efavirenz concentration was 2.23 (1.66 to 4.10) μg/mL. On multivariable analyses (adjusting for age, sex, body mass index, and ART duration) doubling of efavirenz concentrations resulted in mean changes in mmol/L (95%CI) of: total cholesterol (0.40 [0.22 to 0.59]), LDL cholesterol (0.19 [0.04 to 0.30]), HDL cholesterol (0.14 [0.07 to 0.20]), triglycerides (0.17 [0.03 to 0.33]), fasting glucose (0.18 [0.03 to 0.33]), and 2-h glucose concentrations (0.33 [0.08 to 0.60]). Among 57 participants with CYP2B6 genotype data, associations between slow metabolizer genotypes and metabolic profiles were generally consistent with those for measured efavirenz concentrations.Higher plasma efavirenz concentrations are associated with higher plasma lipid and glucose concentrations. This may have implications for long-term cardiovascular complications of efavirenz-based ART, particularly among populations with high prevalence of CYP2B6 slow metabolizer genotypes.
Project description:Immune cells of the liver must be able to recognize and react to pathogens yet remain tolerant to food molecules and other nonpathogens. Dendritic cells (DCs) are believed to contribute to hepatic tolerance. Lipids have been implicated in dysfunction of DCs in cancer. Therefore, we investigated whether high lipid content in liver DCs affects induction of tolerance.Mouse and human hepatic nonparenchymal cells were isolated by mechanical and enzymatic digestion. DCs were purified by fluorescence-activated cell sorting or with immunomagnetic beads. DC lipid content was assessed by flow cytometry, immune fluorescence, and electron microscopy and by measuring intracellular component lipids. DC activation was determined from surface phenotype and cytokine profile. DC function was assessed in T-cell, natural killer (NK) cell, and NKT cell coculture assays as well as in vivo.We observed 2 distinct populations of hepatic DCs in mice and humans based on their lipid content and expression of markers associated with adipogenesis and lipid metabolism. This lipid-based dichotomy in DCs was unique to the liver and specific to DCs compared with other hepatic immune cells. However, rather than mediate tolerance, the liver DC population with high concentrations of lipid was immunogenic in multiple models; they activated T cells, NK cells, and NKT cells. Conversely, liver DCs with low levels of lipid induced regulatory T cells, anergy to cancer, and oral tolerance. The immunogenicity of lipid-rich liver DCs required their secretion of tumor necrosis factor ? and was directly related to their high lipid content; blocking DC synthesis of fatty acids or inhibiting adipogenesis (by reducing endoplasmic reticular stress) reduced DC immunogenicity.Human and mouse hepatic DCs are composed of distinct populations that contain different concentrations of lipid, which regulates immunogenic versus tolerogenic responses in the liver.
Project description:Reduced concentrations of docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (AA, 20:4n-6) have been reported in the postmortem bipolar disorder (BD) brain. Additionally, an increased prevalence of BD has been related to low dietary intake of fish, and dietary supplements containing fish products or DHA have been reported to ameliorate BD symptoms. These observations suggest that brain lipid metabolism, particularly involving DHA, is disturbed in BD. To test this suggestion, concentrations of different lipids were measured using internal standards in postmortem frontal cortex from eight BD patients and six matched controls. Compared with control cortex, the BD cortex showed no statistically significant difference in mean concentrations (per gram wet weight) of "stable" lipids (total lipid, total phospholipid, individual phospholipids, or cholesterol), of unesterified fatty acids, or of esterified DHA or AA within stable lipids. Fractional esterified AA and DHA concentrations also did not differ significantly between groups. Some fatty acid concentration differences were found in low-abundant cholesteryl ester. These results do not support the hypothesis of disturbed brain lipid concentrations, including concentrations of AA and DHA, in BD. Positron emission tomography might be used, however, to see if brain AA or DHA kinetics are disturbed in the disease.