Plasma S1P and Sphingosine are not Different Prior to Pre-Eclampsia in Women at High Risk of Developing the Disease.

Sphingolipids like sphingosine-1-phosphate (S1P) have been implicated in the pathophysiology of pre-eclampsia. We hypothesized that plasma S1P would be increased in women at high risk of developing pre-eclampsia who subsequently develop the disease. Low circulating placental growth factor (PlGF) is known to be associated with development of pre-eclampsia; so further, we hypothesized that increased S1P would be associated with concurrently low PlGF. This was a case-control study using stored maternal blood samples from 14 to 24 weeks of pregnancy, collected from 95 women at increased risk of pre-eclampsia. Pregnancy outcome was classified as uncomplicated, preterm pre-eclampsia (<37 weeks), or term pre-eclampsia. Plasma lipids were extracted and analyzed by ultraperformance liquid chromatography coupled to electrospray ionization MS/MS to determine concentrations of S1P and sphingosine. Median plasma S1P was 0.339 nmol/ml, and median sphingosine was 6.77 nmol/l. There were no differences in the plasma concentrations of S1P or sphingosine in women who subsequently developed pre-eclampsia, no effect of gestational age, fetal sex, ethnicity, or the presence of pre-existing hypertension. There was a correlation between S1P and sphingosine plasma concentration (P < 0.0001). There was no relationship between S1P or sphingosine with PlGF. Previous studies have suggested that plasma S1P may be a biomarker of pre-eclampsia. In our larger study, we failed to demonstrate there are women at high risk of developing the disease. We did not show a relationship with known biomarkers of the disease, suggesting that S1P is unlikely to be a useful predictor of the development of pre-eclampsia later in pregnancy.

Heritability and family-based GWAS analyses of the N-acyl ethanolamine and ceramide plasma lipidome.

Signalling lipids of the N-acyl ethanolamine (NAE) and ceramide (CER) classes have emerged as potential biomarkers of cardiovascular disease (CVD). We sought to establish the heritability of plasma NAEs (including the endocannabinoid anandamide) and CERs, to identify common DNA variants influencing the circulating concentrations of the heritable lipids, and assess causality of these lipids in CVD using 2-sample Mendelian randomization (2SMR). Nine NAEs and 16 CERs were analyzed in plasma samples from 999 members of 196 British Caucasian families, using targeted ultra-performance liquid chromatography with tandem mass spectrometry. All lipids were significantly heritable (h2 = 36-62%). A missense variant (rs324420) in the gene encoding the enzyme fatty acid amide hydrolase (FAAH), which degrades NAEs, associated at genome-wide association study (GWAS) significance (P < 5 × 10-8) with four NAEs (DHEA, PEA, LEA and VEA). For CERs, rs680379 in the SPTLC3 gene, which encodes a subunit of the rate-limiting enzyme in CER biosynthesis, associated with a range of species (e.g. CER[N(24)S(19)]; P = 4.82 × 10-27). We observed three novel associations between SNPs at the CD83, SGPP1 and DEGS1 loci, and plasma CER traits (P < 5 × 10-8). 2SMR in the CARDIoGRAMplusC4D cohorts (60 801 cases; 123 504 controls) and in the DIAGRAM cohort (26 488 cases; 83 964 controls), using the genetic instruments from our family-based GWAS, did not reveal association between genetically determined differences in CER levels and CVD or diabetes. Two of the novel GWAS loci, SGPP1 and DEGS1, suggested a casual association between CERs and a range of haematological phenotypes, through 2SMR in the UK Biobank, INTERVAL and UKBiLEVE cohorts (n = 110 000-350 000).

Current insights into skin lipids and their roles in cutaneous health and disease.

PURPOSE OF REVIEW: The unique and complex array of cutaneous lipids include essential components of the skin structure and signalling molecules mediating homeostasis and inflammation. Understanding skin lipid biology and metabolism can support our comprehension of health and disease, including systemic conditions with cutaneous involvement. RECENT FINDINGS: Lipids found on the skin surface, produced by both the host and resident microbes, maintain and regulate the skin microbiome and the epidermal barrier, whilst altered contributions from either source can be detrimental to skin health. The unique lipid composition of the epidermal barrier is essential for its function, and recent studies have expanded our understanding of epidermal ceramide production. This has been supported by improved models available for skin research, including organotypic skin models enabling in-vitro production of complex acylceramides for the first time, and model systems facilitating in-silico exploration of the lipid profile changes observed in clinical samples. Studies have revealed further involvement of lipid mediators such as eicosanoids in cutaneous inflammation, as well as immune regulation in both healthy and diseased skin. SUMMARY: Skin lipids offer exciting opportunities as therapeutic targets for many conditions, whether through topical interventions or nutritional supplementation.

Omega-3 carboxylic acids and fenofibrate differentially alter plasma lipid mediators in patients with non-alcoholic fatty liver disease.

Fibrates and omega-3 polyunsaturated acids are used for the treatment of hypertriglyceridemia but have not demonstrated consistent effects on cardiovascular (CV) risk. In this study, we investigate how these two pharmacological agents influence plasma levels of bioactive lipid mediators, aiming to explore their efficacy beyond that of lipid-lowering agents. Plasma from overweight patients with non-alcoholic fatty liver disease (NAFLD) and hypertriglyceridemia, participating in a randomized placebo-controlled study investigating the effects of 12 weeks treatment with fenofibrate or omega-3 free carboxylic acids (OM-3CA) (200 mg or 4 g per day, respectively), were analyzed for eicosanoids and related PUFA species, N-acylethanolamines (NAE) and ceramides. OM-3CA reduced plasma concentrations of proinflammatory PGE2 , as well as PGE1 , PGD1 and thromboxane B2 but increased prostacyclin, and eicosapentaenoic acid- and docosahexaenoic acid-derived lipids of lipoxygenase and cytochrome P450 monooxygenase (CYP) (e.g., 17-HDHA, 18-HEPE, 19,20-DiHDPA). Fenofibrate reduced plasma concentrations of vasoactive CYP-derived eicosanoids (DHETs). Although OM-3CA increased plasma levels of the NAE docosahexaenoyl ethanolamine and docosapentaenoyl ethanolamine, and fenofibrate increased palmitoleoyl ethanolamine, the effect of both treatments may have been masked by the placebo (olive oil). Fenofibrate was more efficacious than OM-3CA in significantly reducing plasma ceramides, pro-inflammatory lipids associated with CV disease risk. Neither treatment affected putative lipid species associated with NAFLD. Our results show that OM-3CA and fenofibrate differentially modulate the plasma mediator lipidome, with OM-3CA promoting the formation of lipid mediators with potential effects on chronic inflammation, while fenofibrate mainly reducing ceramides. These findings suggest that both treatments could ameliorate chronic inflammation with possible impact on disease outcomes, independent of triglyceride reduction.

Omega-3 polyunsaturated fatty acids protect against inflammation through production of LOX and CYP450 lipid mediators: relevance for major depression and for human hippocampal neurogenesis.

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can exert antidepressant, anti-inflammatory and neuroprotective properties, but the exact molecular mechanism underlying their effects is still not fully understood. We conducted both in vitro and clinical investigations to test which EPA or DHA metabolites are involved in these anti-inflammatory, neuroprotective and antidepressant effects. In vitro, we used the human hippocampal progenitor cell line HPC0A07/03C, and pre-treated cells with either EPA or DHA, followed by interleukin 1beta (IL1ß), IL6 and interferon-alpha (IFN-α). Both EPA and DHA prevented the reduction in neurogenesis and the increase in apoptosis induced by these cytokines; moreover, these effects were mediated by the lipoxygenase (LOX) and cytochrome P450 (CYP450) EPA/DHA metabolites, 5-hydroxyeicosapentaenoic acid (HEPE), 4-hydroxydocosahexaenoic acid (HDHA), 18-HEPE, 20-HDHA, 17(18)-epoxyeicosatetraenoic acid (EpETE) and 19(20)-epoxydocosapentaenoic acid (EpDPA), detected here for the first time in human hippocampal neurones using mass spectrometry lipidomics of the supernatant. In fact, like EPA/DHA, co-treatment with these metabolites prevented cytokines-induced reduction in neurogenesis and apoptosis. Moreover, co-treatment with 17(18)-EpETE and 19(20)-EpDPA and the soluble epoxide hydroxylase (sEH) inhibitor, TPPU (which prevents their conversion into dihydroxyeicosatetraenoic acid (DiHETE)/ dihydroxydocosapentaenoic acid (DiHDPA) metabolites) further enhanced their neurogenic and anti-apoptotic effects. Interestingly, these findings were replicated in a sample of n = 22 patients with a DSM-IV Major Depressive Disorder, randomly assigned to treatment with either EPA (3.0 g/day) or DHA (1.4 g/day) for 12 weeks, with exactly the same LOX and CYP450 lipid metabolites increased in the plasma of these patients following treatment with their precursor, EPA or DHA, and some evidence that higher levels of these metabolites were correlated with less severe depressive symptoms. Overall, our study provides the first evidence for the relevance of LOX- and CYP450-derived EPA/DHA bioactive lipid metabolites as neuroprotective molecular targets for human hippocampal neurogenesis and depression, and highlights the importance of sEH inhibitors as potential therapeutic strategy for patients suffering from depressive symptoms.

Genetic analyses of circulating PUFA-derived mediators identifies heritable dihydroxyeicosatrienoic acid species.

Estimates of heritability are the first step in identifying a trait with substantial variation due to genetic factors. Large-scale genetic analyses can identify the DNA variants that influence the levels of circulating lipid species and the statistical technique Mendelian randomisation can use these DNA variants to address potential causality of these lipids in disease. We estimated the heritability of plasma eicosanoids, octadecanoids and docosanoids to identify those lipid species with substantial heritability. We analysed plasma lipid mediators in 31 White British families (196 participants) ascertained for high blood pressure and deeply clinically and biochemically phenotyped over a 25-year period. We found that the dihydroxyeicosatrienoic acid (DHET) species, 11,12-DHET and 14,15-DHET, products of arachidonic acid metabolism by cytochrome P450 (CYP) monooxygenase and soluble epoxide hydrolase (sEH), exhibited substantial heritability (h2 = 33%-37%; Padj<0.05). Identification of these two heritable bioactive lipid species allows for future large-scale, targeted, lipidomics-genomics analyses to address causality in cardiovascular and other diseases.

Ultraviolet radiation-induced degradation of dermal extracellular matrix and protection by green tea catechins: a randomized controlled trial.

BACKGROUND: Loss and remodelling of the dermal extracellular matrix (ECM) are key features of photodamaged human skin. Green tea catechins (GTCs) have been explored for their anti-inflammatory and chemopreventive properties, but data on the impact of GTCs on ultraviolet radiation (UVR)-induced changes to the dermal ECM are lacking. AIM: To investigate the effect of an inflammatory dose of solar-simulated UVR on human dermal ECM and potential for protection by GTCs in a double-blind randomized controlled trial. METHODS: In total, 50 healthy white (Fitzpatrick skin type I-II) adults aged 18-65 years were randomized to a combination of GTCs 540 mg plus vitamin C 50 mg or to placebo twice daily for 12 weeks. The impact of solar-simulated UVR at 3 × minimal erythema dose on the dermal collagen and elastic fibre networks was assessed by histology and immunohistochemistry in all participants at baseline. The impact of GTC supplementation on UVR-induced effects was compared between the groups post-supplementation. RESULTS: The area of papillary dermis covered by collagen and elastic fibres was significantly lower (P < 0.001) in UVR-exposed skin than in unexposed skin. Significantly lower levels of fibrillin-rich microfibrils (P = 0.02), fibulin-2 (P < 0.001) and fibulin-5 (P < 0.001) were seen in UVR-exposed than unexposed skin, while procollagen-1 deposition was significantly higher in UVR-exposed skin (P = 0.01). Following GTC supplementation, the UVR-induced change in fibulin-5 was abrogated in the active group but not the placebo group, with no difference between the two groups for other components. CONCLUSIONS: Acute UVR induced significant changes in the human dermal collagen and elastic fibre networks, whereas oral GTCs conferred specific UVR protection to fibulin-5. Future studies could explore the impact of GTCs on the effects of repeated suberythemal UVR exposure of human skin.

The use of missing values in proteomic data-independent acquisition mass spectrometry to enable disease activity discrimination.

MOTIVATION: Data-independent acquisition mass spectrometry allows for comprehensive peptide detection and relative quantification than standard data-dependent approaches. While less prone to missing values, these still exist. Current approaches for handling the so-called missingness have challenges. We hypothesized that non-random missingness is a useful biological measure and demonstrate the importance of analysing missingness for proteomic discovery within a longitudinal study of disease activity. RESULTS: The magnitude of missingness did not correlate with mean peptide concentration. The magnitude of missingness for each protein strongly correlated between collection time points (baseline, 3 months, 6 months; R = 0.95-0.97, confidence interval = 0.94-0.97) indicating little time-dependent effect. This allowed for the identification of proteins with outlier levels of missingness that differentiate between the patient groups characterized by different patterns of disease activity. The association of these proteins with disease activity was confirmed by machine learning techniques. Our novel approach complements analyses on complete observations and other missing value strategies in biomarker prediction of disease activity. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Dynamics of the human skin mediator lipidome in response to dietary ω-3 fatty acid supplementation.

Nutritional supplementation with fish oil or ω-3 (n-3) polyunsaturated fatty acids (PUFAs) has potential benefits for skin inflammation. Although the differential metabolism of the main n-3PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) could lead to distinct activities, there are no clinical studies comparing their relative efficacy in human skin. Following a 10-wk oral supplementation of healthy volunteers and using mass spectrometry-based lipidomics, we found that n-3PUFA mainly affected the epidermal mediator lipidome. EPA was more efficient than DHA in reducing production of arachidonic acid-derived lipids, and both n-3PUFA lowered N-acyl ethanolamines. In UV radiation-challenged skin (3 times the minimum erythemal dose), EPA attenuated the production of proinflammatory lipids, whereas DHA abrogated the migration of Langerhans cells, as assessed by immunohistochemistry. Interestingly, n-3PUFA increased the infiltration of CD4+ and CD8+ T cells but did not alter the erythemal response, either the sunburn threshold or the resolution of erythema, as assessed by spectrophotometric hemoglobin index readings. As EPA and DHA differentially impact cutaneous inflammation through changes in the network of epidermal lipids and dendritic and infiltrating immune cells, they should be considered separately when designing interventions for cutaneous disease.-Kendall, A. C., Pilkington, S. M., Murphy, S. A., Del Carratore, F., Sunarwidhi, A. L., Kiezel-Tsugunova, M., Urquhart, P., Watson, R. E. B., Breitling, R., Rhodes, L. E., Nicolaou, A. Dynamics of the human skin mediator lipidome in response to dietary ω-3 fatty acid supplementation.

Integrated eicosanoid lipidomics and gene expression reveal decreased prostaglandin catabolism and increased 5-lipoxygenase expression in aggressive subtypes of endometrial cancer.

Eicosanoids comprise a diverse group of bioactive lipids which orchestrate inflammation, immunity, and tissue homeostasis, and whose dysregulation has been implicated in carcinogenesis. Among the various eicosanoid metabolic pathways, studies of their role in endometrial cancer (EC) have very much been confined to the COX-2 pathway. This study aimed to determine changes in epithelial eicosanoid metabolic gene expression in endometrial carcinogenesis; to integrate these with eicosanoid profiles in matched clinical specimens; and, finally, to investigate the prognostic value of candidate eicosanoid metabolic enzymes. Eicosanoids and related mediators were profiled using liquid chromatography-tandem mass spectrometry in fresh frozen normal, hyperplastic, and cancerous (types I and II) endometrial specimens (n = 192). Sample-matched epithelia were isolated by laser capture microdissection and whole genome expression analysis was performed using microarrays. Integration of eicosanoid and gene expression data showed that the accepted paradigm of increased COX-2-mediated prostaglandin production does not apply in EC carcinogenesis. Instead, there was evidence for decreased PGE2 /PGF2α inactivation via 15-hydroxyprostaglandin dehydrogenase (HPGD) in type II ECs. Increased expression of 5-lipoxygenase (ALOX5) mRNA was also identified in type II ECs, together with proportional increases in its product, 5-hydroxyeicosatetraenoic acid (5-HETE). Decreased HPGD and elevated ALOX5 mRNA expression were associated with adverse outcome, which was confirmed by immunohistochemical tissue microarray analysis of an independent series of EC specimens (n = 419). While neither COX-1 nor COX-2 protein expression had prognostic value, low HPGD combined with high ALOX5 expression was associated with the worst overall and progression-free survival. These findings highlight HPGD and ALOX5 as potential therapeutic targets in aggressive EC subtypes. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Training Two-Wheel Bike Skills in Children with Cerebral Palsy: A Practice Survey of Therapists in Australia.

Aim: To describe current practices of physiotherapists and occupational therapists when training two-wheel bike skills in children with cerebral palsy (CP) within an International Classification of Functioning, Disability and Health (ICF) framework. Methods: Ninety-five physiotherapists and occupational therapists working with children with CP in Australia completed a customized online survey. Survey questions related to: eligibility, initial assessment, intervention characteristics, and evaluation of effectiveness. Open-ended responses were analyzed using deductive content analysis. Close-ended questions were analyzed using descriptive statistics. The ICF was used as a framework for coding and reporting. Results: Body structure and function factors were most frequently considered in eligibility (56% of observations) and assessment (47%). Activity and participation-related factors were considered more in intervention (42%) and evaluation (75%). While functional training approaches were predominant, intervention characteristics varied markedly. Excepting goal-related tools, few measures were identified for assessment or evaluation of effectiveness. Environmental and personal factors were seldom considered across practice areas. Conclusions: Current two-wheel bike skills training for children with CP in Australia appears highly variable. Development and testing of bike skills-specific outcome measures and interventions and guidance for therapists on consideration of environmental and personal factors are warranted.

Fatty acids and related lipid mediators in the regulation of cutaneous inflammation.

Human skin has a distinct profile of fatty acids and related bioactive lipid mediators that regulate many aspects of epidermal and dermal homeostasis, including immune and inflammatory reactions. Sebum lipids act as effective antimicrobial agents, shape immune cell communications and contribute to the epidermal lipidome. The essential fatty acid linoleic acid is crucial for the structure of the epidermal barrier, while polyunsaturated fatty acids act as precursors to eicosanoids, octadecanoids and docosanoids through cyclooxygenase, lipoxygenase and cytochrome P450 monooxygenase-mediated reactions, and endocannabinoids and N-acyl ethanolamines. Cross-communication between these families of bioactive lipids suggests that their cutaneous activities should be considered as part of a wider metabolic network that can be targeted to maintain skin health, control inflammation and improve skin pathologies.

Seasonal changes in epidermal ceramides are linked to impaired barrier function in acne patients.

Acne skin demonstrates increased transepidermal water loss (TEWL) compared with healthy skin, which may be due, in part, to altered ceramide (CER) levels. We analysed ceramides in the stratum corneum of healthy and acne skin, and studied seasonal variation over the course of a year. Using ultraperformance liquid chromatography with electrospray ionisation and tandem mass spectrometry (UPLC/ESI-MS/MS), we identified 283 ceramides. Acne-affected skin demonstrated overall lower levels of ceramides, with notable reductions in CER[NH] and CER[AH] ceramides, as well as the acylceramides CER[EOS] and CER[EOH]; these differences were more apparent in the winter months. Lower ceramide levels reflected an increase in TEWL in acne, compared with healthy skin, which partly resolves in the summer. Individual ceramide species with 18-carbon 6-hydroxysphingosine (H) bases (including CER[N(24)H(18)], CER[N(26)H(18)], CER[A(24)H(18)], CER[A(26)H(18)]) were significantly reduced in acne skin, suggesting that CER[NH] and CER[AH] species may be particularly important in a healthy skin barrier.

Lipidomics for translational skin research: A primer for the uninitiated.

Healthy skin depends on a unique lipid profile to form a barrier that confers protection and prevents excessive water loss, aids cell-cell communication and regulates cutaneous homoeostasis and inflammation. Alterations in the cutaneous lipid profile can have severe consequences for skin health and have been implicated in numerous inflammatory skin conditions. Thus, skin lipidomics is increasingly of interest, and recent developments in mass spectrometry-based analytical technologies can deliver in-depth investigation of cutaneous lipids, providing insight into their role and mechanism of action. The choice of tissue sampling technique and analytical approach depends on the location and chemistry of the lipid of interest. Lipidomics can be conducted by various mass spectrometry approaches, including different chromatography and ionisation techniques. Targeted mass spectrometry is a sensitive approach for measuring low-abundance signalling lipids, such as eicosanoids, endocannabinoids and ceramides. This approach requires specific extraction, chromatography and mass spectrometry protocols to quantitate the lipid targets. Untargeted mass spectrometry reveals global changes and allows analysis of hundreds of complex lipids across a range of lipid classes, including phospholipids, glycerophospholipids, cholesteryl esters and sphingolipids. Mass spectrometry lipid imaging, including matrix-assisted laser desorption ionisation mass spectrometry and desorption electrospray ionisation mass spectrometry, can reveal information about abundance and anatomical distribution of lipids within a single skin sample. Skin lipidomics can provide qualitative and quantitative data on hundreds of biologically relevant lipid species with different properties and activities, all found within a single skin sample, and support translational studies exploring the involvement of lipids in skin health and disease.

The prostanoid pathway contains potential prognostic markers for glioblastoma.

Prostanoids derived from the activity of cyclooxygenases and their respective synthases contribute to both active inflammation and immune response in the tumor microenvironment. Their synthesis, deactivation and role in glioma biology have not yet been fully explored and require further study. Using quantitative real time PCR, gas chromatography/ electron impact mass spectrometry and liquid chromatography/ electrospray ionization tandem mass spectrometry, we have further characterized the prostanoid pathway in grade IV glioblastoma (GBM). We observed significant correlations between high mRNA expression levels and poor patient survival for microsomal PGE synthase 1 (mPGES1) and prostaglandin reductase 1 (PTGR1). Conversely, high mRNA expression levels for 15-hydroxyprostaglandin dehydrogenase (15-HPGD) were correlated with better patient survival. GBMs had a higher quantity of the prostanoid precursor, arachidonic acid, versus grade II/III tumors and in GBMs a significant positive correlation was found between arachidonic acid and PGE2 content. GBMs also had higher concentrations of TXB2, PGD2, PGE2 and PGF2α versus grade II/III tumors. A significant decrease in survival was detected for high versus low PGE2, PGE2 + PGE2 deactivation products (PGEMs) and PGF2α in GBM patients. Our data show the potential importance of prostanoid metabolism in the progression towards GBM and provide evidence that higher PGE2 and PGF2α concentrations in the tumor are correlated with poorer patient survival. Our findings highlight the potential importance of the enzymes 15-HPGD and PTGR1 as prognostic biomarkers which could be used to predict survival outcome of patients with GBM.

Lipid functions in skin: Differential effects of n-3 polyunsaturated fatty acids on cutaneous ceramides, in a human skin organ culture model.

Ceramides are important for skin health, with a multitude of species found in both dermis and epidermis. The epidermis contains linoleic acid-Ester-linked Omega-hydroxylated ceramides of 6-Hydroxy-sphingosine, Sphingosine and Phytosphingosine bases (CER[EOH], CER[EOS] and CER[EOP], respectively), that are crucial for the formation of the epidermal barrier, conferring protection from environmental factors and preventing trans-epidermal water loss. Furthermore, a large number of ceramides, derivatives of the same sphingoid bases and various fatty acids, are produced by dermal and epidermal cells and perform signalling roles in cell functions ranging from differentiation to apoptosis. Supplementation with the n-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have shown promise as therapeutic agents in a number of inflammatory skin conditions, altering the lipid profile of the skin and production of bioactive lipids such as the eicosanoids, docosanoids and endocannabinoids. In this study we wished to investigate whether EPA and DHA could also affect the ceramide profile in epidermis and dermis, and, in this way, contribute to formation of a robust lipid barrier and ceramide-mediated regulation of skin functions. Ex vivo skin explants were cultured for 6days, and supplemented with EPA or DHA (50µM). Liquid chromatography coupled to tandem mass spectrometry with electrospray ionisation was used to assess the prevalence of 321 individual ceramide species, and a number of sphingoid bases, phosphorylated sphingoid bases, and phosphorylated ceramides, within the dermis and epidermis. EPA augmented dermal production of members of the ceramide families containing Non-hydroxy fatty acids and Sphingosine or Dihydrosphingosine bases (CER[NS] and CER[NDS], respectively), while epidermal CER[EOH], CER[EOS] and CER[EOP] ceramides were not affected. DHA did not significantly affect ceramide production. Ceramide-1-phosphate levels in the epidermis, but not the dermis, increased in response to EPA, but not DHA. This ex vivo study shows that dietary supplementation with EPA has the potential to alter the ceramide profile of the skin, and this may contribute to its anti-inflammatory profile. This has implications for formation of the epidermal lipid barrier, and signalling pathways within the skin mediated by ceramides and other sphingolipid species. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.

Serum endocannabinoids and N-acyl ethanolamines and the influence of simulated solar UVR exposure in humans in vivo.

Solar ultraviolet radiation (UVR) exposure of human skin has beneficial and harmful effects on health, including impact on immune function, inflammation and reportedly mood, but these are not fully elucidated. Since the endocannabinoid system is implicated in many activities including mood alteration, our objective was to (i) determine and quantify circulating levels of a wide range of endocannabinoid and N-acyl ethanolamine (NAE) species (ii) evaluate whether these are modulated by cutaneous UVR exposures, as attained through repeated low level summer sunlight exposure. Wearing goggles to prevent eye exposure, 16 healthy volunteers (23-59 y; 10 light skin, phototype II, and 6 dark skin, phototype V) received the same UVR exposures (1.3 SED, 95% UVA/5% UVB) thrice weekly for 6 weeks, whilst casually dressed to expose ∼35% skin surface area. Blood samples were taken at baseline, days 1, 3 and 5 of week one, then at weekly intervals, and analysed by LC-MS/MS. Eleven endocannabinoids and NAEs were detected and quantified at baseline, with N-palmitoyl ethanolamine the most abundant (30% of total). Levels did not vary according to phototype (p > 0.05), except for the NAE docosapentaenoyl ethanolamide, which was higher in phototype II than V (p = 0.0002). Level of the endocannabinoid, 2-AG, was elevated during the UVR exposure course (p < 0.05 vs. baseline for all subjects; p < 0.01 for each phototype group), with maximum levels reached by week 2-3, while NAE species did not significantly alter. These findings suggest differential involvement of the cutaneous endocannabinoid system in low dose solar UVR responses in humans.

A comparison of heart rate variability, n-3 PUFA status and lipid mediator profile in age- and BMI-matched middle-aged vegans and omnivores.

Low heart rate variability (HRV) predicts sudden cardiac death. Long-chain (LC) n-3 PUFA (C20-C22) status is positively associated with HRV. This cross-sectional study investigated whether vegans aged 40-70 years (n 23), whose diets are naturally free from EPA (20 : 5n-3) and DHA (22 : 6n-3), have lower HRV compared with omnivores (n 24). Proportions of LC n-3 PUFA in erythrocyte membranes, plasma fatty acids and concentrations of plasma LC n-3 PUFA-derived lipid mediators were significantly lower in vegans. Day-time interbeat intervals (IBI), adjusted for physical activity, age, BMI and sex, were significantly shorter in vegans compared with omnivores (mean difference -67 ms; 95 % CI -130, -3·4, P50 % and high-frequency power) were similarly lower in vegans, with no differences during sleep. In conclusion, vegans have higher 24 h SDNN, but lower day-time HRV and shorter day-time IBI relative to comparable omnivores. Vegans may have reduced availability of precursor markers for pro-resolving lipid mediators; it remains to be determined whether there is a direct link with impaired cardiac function in populations with low-n-3 status.

Targeted lipidomic strategies for oxygenated metabolites of polyunsaturated fatty acids.

Oxidation of polyunsaturated fatty acids (PUFA) through enzymatic or non-enzymatic free radical-mediated reactions can yield an array of lipid metabolites including eicosanoids, octadecanoids, docosanoids and related species. In mammals, these oxygenated PUFA mediators play prominent roles in the physiological and pathological regulation of many key biological processes in the cardiovascular, renal, reproductive and other systems including their pivotal contribution to inflammation. Mass spectrometry-based technology platforms have revolutionized our ability to analyze the complex mixture of lipid mediators found in biological samples, with increased numbers of metabolites that can be simultaneously quantified from a single sample in few analytical steps. The recent development of high-sensitivity and high-throughput analytical tools for lipid mediators affords a broader view of these oxygenated PUFA species, and facilitates research into their role in health and disease. In this review, we illustrate current analytical approaches for a high-throughput lipidomic analysis of eicosanoids and related mediators in biological samples. This article is part of a Special Issue entitled "Oxygenated metabolism of PUFA: analysis and biological relevance."