Docosanoids and elovanoids from omega-3 fatty acids are pro-homeostatic modulators of inflammatory responses, cell damage and neuroprotection

Proteomic and Cytokine Profiling in Plasma from Patients with Normal-Tension Glaucoma and Ocular Hypertension

Primary open-angle glaucoma (POAG) is subdivided depending on eye pressure. Patients with normal-tension glaucoma (NTG) have never had high intraocular pressure (IOP) measured while patients with ocular hypertension (OHT) have high eye pressure but no signs of glaucoma. Although IOP is considered to be a risk factor for all glaucoma patients, it is reasonable to assume that other risk factors such as inflammation play a role. We aimed to characterize the proteome and cytokine profile during hypoxia in plasma from patients with NTG (n = 10), OHT (n = 10), and controls (n = 10). Participants were exposed to hypoxia for two hours, followed by 30 min of normoxia. Samples were taken before ("baseline"), during ("hypoxia"), and after hypoxia ("recovery"). Proteomics based on liquid chromatography coupled with mass spectrometry (LC-MS) was performed. Cytokines were measured by Luminex assays. Bioinformatic analyses indicated the involvement of complement and coagulation cascades in NTG and OHT. Regulation of high-density lipoprotein 3 (HDL3) apolipoproteins suggested that changes in cholesterol metabolism are related to OHT. Hypoxia decreased the level of tumor necrosis factor-α (TNF-α) in OHT patients compared to controls. Circulating levels of interleukin-1β (IL-1β) and C-reactive protein (CRP) were decreased in NTG patients compared to controls during hypoxia. After recovery, plasma interleukin-6 (IL-6) was upregulated in patients with NTG and OHT. Current results indicate an enhanced systemic immune response in patients with NTG and OHT, which correlates with pathogenic events in glaucoma. Apolipoproteins may have anti-inflammatory effects, enabling OHT patients to withstand inflammation and development of glaucoma despite high IOP.

ω-3 PUFA for Secondary Prevention of White Matter Lesions and Neuronal Integrity Breakdown in Older Adults: A Randomized Clinical Trial

Importance

Older adults with lower intake and tissue levels of long-chain ω-3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA; 20:5) and docosahexaenoic acid (DHA; 22:6) have more brain white matter lesions (WMLs), an association suggesting that small-vessel ischemic disease, a major contributor to the development of dementia, including Alzheimer disease, may be preventable through ω-3 treatment.

Objective

To determine whether ω-3 treatment reduces WML accumulation in older adults without dementia harboring WMLs and with suboptimal ω-3 status.

Design, Setting, and Participants

This quadruple-blinded, placebo-controlled, randomized clinical trial with treatment stratification by apolipoprotein E ε4 allele (APOE*E4) carrier status used linear mixed-effects models to estimate mean annual change between groups. The study was conducted at Oregon Health & Science University, a major academic medical center in the Pacific Northwest, from May 2014 to final participant visit in September 2019. Data analysis concluded in July 2022. Participants were adults without dementia aged 75 years and older with WMLs greater than or equal to 5 cm3 and plasma ω-3 PUFA less than 5.5 weight percentage of total.

Intervention

Three-year treatment with 1.65 g of ω-3 PUFA (975 mg of EPA and 650 mg of DHA) vs a soybean oil placebo matched for taste, smell, and appearance.

Main Outcomes and Measures

The primary outcome was annual WML progression measured using magnetic resonance imaging. Secondary outcomes included diffusion tensor imaging of fractional anisotropy (DTI-FA), representing neuronal integrity breakdown.

Results

A total of 102 participants (62 women [60.8%]; mean age, 81 years [range, 75-96 years]) were equally randomized, 51 per treatment group. Although the ω-3 group had less annual WML accumulation than the placebo group, the difference was not statistically significant (1.19 cm3 [95% CI, 0.64-1.74 cm3] vs 1.34 cm3 [95% CI, 0.80-1.88 cm3]; P = .30). Similarly, the ω-3 group had less annual DTI-FA decline than the placebo group, but the difference was not statistically significant (-0.0014 mm2/s [95% CI, -0.0027 to 0.0002 mm2/s] vs -0.0027 mm2/s [95% CI, -0.0041 to -0.0014 mm2/s]; P = .07). Among APOE*E4 carriers, the annual DTI-FA decline was significantly lower in the group treated with ω-3 than the placebo group (-0.0016 mm2/s [95% CI, -0.0032 to 0.0020 mm2/s] vs -0.0047 mm2/s [95% CI, -0.0067 to -0.0025 mm2/s]; P = .04). Adverse events were similar between treatment groups.

Conclusions and Relevance

In this 3-year randomized clinical trial, ω-3 treatment was safe and well-tolerated but failed to reach significant reductions in WML accumulation or neuronal integrity breakdown among all participants, which may be attributable to sample size limitations. However, neuronal integrity breakdown was reduced by ω-3 treatment in APOE*E4 carriers, suggesting that this treatment may be beneficial for this specific group.

Trial Registration

ClinicalTrials.gov Identifier: NCT01953705.

Differential effect of an evolving amyloid and tau pathology on brain phospholipids and bioactive lipid mediators in rat models of Alzheimer-like pathology

BACKGROUND

Brain inflammation contributes significantly to the pathophysiology of Alzheimer's disease, and it is manifested by glial cell activation, increased production of cytokines/chemokines, and a shift in lipid mediators from a pro-homeostatic to a pro-inflammatory profile. However, whether the production of bioactive lipid mediators is affected at earlier stages, prior to the deposition of Aβ plaques and tau hyperphosphorylation, is unknown. The differential contribution of an evolving amyloid and tau pathology on the composition and abundance of membrane phospholipids and bioactive lipid mediators also remains unresolved.

METHODS

In this study, we examined the cortical levels of DHA- and AA-derived bioactive lipid mediators and of membrane phospholipids by liquid chromatography with tandem mass spectrometry in transgenic rat models of the Alzheimer's-like amyloid and tau pathologies at early and advanced pathological stages.

RESULTS

Our findings revealed a complex balance between pro-inflammatory and pro-resolving processes in which tau pathology has a more pronounced effect compared to amyloid pathology. At stages preceding tau misfolding and aggregation, there was an increase in pro-resolving lipid mediators (RVD6 and NPD1), DHA-containing phospholipids and IFN-γ levels. However, in advanced tau pathology displaying NFT-like inclusions, neuronal death, glial activation and cognitive deficits, there was an increase in cytokine and PGD2, PGE2, and PGF2α generation accompanied by a drop in IFN-γ levels. This pathology also resulted in a marked increase in AA-containing phospholipids. In comparison, pre-plaque amyloid pathology already presented high levels of cytokines and AA-containing phospholipids together with elevated RVD6 and NPD1 levels. Finally, Aβ plaque deposition was accompanied by a modest increase in prostaglandins, increased AA-containing phospholipids and reduced DHA-containing phospholipids.

CONCLUSIONS

Our findings suggest a dynamic trajectory of inflammatory and lipid mediators in the evolving amyloid and tau pathologies and support their differing roles on membrane properties and, consequentially, on signal transduction.

The negative association between the docosapentaenoic acid intake and the incidence of AMD based on NHANES 2005-2008

Introduction

Age-related macular degeneration (AMD) is an ophthalmic disease that causes visual impairment and is one of the leading causes of blindness in the elderly. Fatty acids are essential nutrients required by the body and play a cornerstone role in the life activities of the body. Many studies have reported that fatty acids are involved in the development of AMD. To confirm this association, we conducted the present study.

Methods

We analyzed the association between all fatty acid intake and AMD using National Health and Nutrition Examination Survey (NHANES) data from 2005-2008. Quantile regression was performed to assess the effect of fatty acids on AMD at different intake levels.

Results

After adjusting for covariates, only saturated fatty acids showed no significant difference between AMD patients and non-AMD patients (23.64 g vs. 26.03 g, p = 0.052). Total fat (70.88 g vs. 78.86 g, p = 0.024), monounsaturated fatty acids (25.87 g vs. 28.95 g, p = 0.019), polyunsaturated fatty acids (15.10 g vs. 17.07 g, p = 0.017) showed significant differences between the two groups. When AMD was considered as an outcome, the association between AMD and docosaentaenoic acid (DPA) was negative in the multivariate logic model (model 1: OR = <0.001, 95% CI = <0.001 ~ 0.734; model 2: OR = <0.001, 95% CI = <0.001 ~ 0.002; model 3: OR = <0.001, 95% CI = <0.001 ~ 0.002). In the quantile regression, DPA was shown to be negatively associated with the presence of AMD only in the fourth quartile in model 2 and model 3 (model 2: OR = <0.001, 95% CI = <0.001 ~ 0.927; model 3: OR = <0.001, 95% CI = <0.001 ~ 0.775).

Discussion

Therefore, based on above results, we concluded that DPA intake could prevent the development of AMD.

The role of adiponectin and its receptor signaling in ocular inflammation-associated diseases

Ocular inflammation-associated diseases are leading causes of global visual impairment, with limited treatment options. Adiponectin, a hormone primarily secreted by adipose tissue, binds to its receptors, which are widely distributed throughout the body, exerting powerful physiological regulatory effects. The protective role of adiponectin in various inflammatory diseases has gained increasing attention in recent years. Previous studies have confirmed the presence of adiponectin and its receptors in the eyes. Furthermore, adiponectin and its analogs have shown potential as novel drugs for the treatment of inflammatory eye diseases. This article summarizes the evidence for the interplay between adiponectin and inflammatory eye diseases and provides new perspectives on the diagnostic and therapeutic possibilities of adiponectin.

Metabolic profiling reveals circulating biomarkers associated with incident and prevalent Parkinson's disease

The metabolic profile predating the onset of Parkinson's disease (PD) remains unclear. We aim to investigate the metabolites associated with incident and prevalent PD and their predictive values in the UK Biobank participants with metabolomics and genetic data at the baseline. A panel of 249 metabolites was quantified using a nuclear magnetic resonance analytical platform. PD was ascertained by self-reported history, hospital admission records and death registers. Cox proportional hazard models and logistic regression models were used to investigate the associations between metabolites and incident and prevalent PD, respectively. Area under receiver operating characteristics curves (AUC) were used to estimate the predictive values of models for future PD. Among 109,790 participants without PD at the baseline, 639 (0.58%) individuals developed PD after one year from the baseline during a median follow-up period of 12.2 years. Sixty-eight metabolites were associated with incident PD at nominal significance (P < 0.05), spanning lipids, lipid constituent of lipoprotein subclasses and ratios of lipid constituents. After multiple testing corrections (P < 9 × 10-4), polyunsaturated fatty acids (PUFA) and omega-6 fatty acids remained significantly associated with incident PD, and PUFA was shared by incident and prevalent PD. Additionally, 14 metabolites were exclusively associated with prevalent PD, including amino acids, fatty acids, several lipoprotein subclasses and ratios of lipids. Adding these metabolites to the conventional risk factors yielded a comparable predictive performance to the risk-factor-based model (AUC = 0.766 vs AUC = 0.768, P = 0.145). Our findings suggested metabolic profiles provided additional knowledge to understand different pathways related to PD before and after its onset.

Hepatotoxicity assessment of innovative nutritional supplements based on olive-oil formulations enriched with natural antioxidants

Introduction

This study focuses on the assessment of extra virgin olive-oil and olive fruit-based formulations enriched with natural antioxidants as potential nutritional supplements for alleviating symptoms and long-term consequences of illnesses whose molecular pathophysiology is affected by oxidative stress and inflammation, such as Alzheimer's disease (AD).

Methods

Besides evaluating cell viability and proliferation capacity of human hepatocellular carcinoma HepG2 cells exposed to formulations in culture, hepatotoxicity was also considered as an additional safety measure using quantitative real-time PCR on RNA samples isolated from the cell cultures and applying approaches of targeted molecular analysis to uncover potential pathway effects through gene expression profiling. Furthermore, the formulations investigated in this work contrast the addition of natural extract with chemical forms and evaluate the antioxidant delivery mode on cell toxicity.

Results

The results indicate minimal cellular toxicity and a significant beneficial impact on metabolic molecular pathways in HepG2 cell cultures, thus paving the way for innovative therapeutic strategies using olive-oil and antioxidants in dietary supplements to minimize the long-term effects of oxidative stress and inflammatory signals in individuals being suffered by disorders like AD.

Discussion

Overall, the experimental design and the data obtained support the notion of applying innovative molecular methodologies and research techniques to evidently advance the delivery, as well as the scientific impact and validation of nutritional supplements and dietary products to improve public health and healthcare outcomes.

Lipid mediators in glaucoma: Unraveling their diverse roles and untapped therapeutic potential

Glaucoma is a complex neurodegenerative disease characterized by optic nerve damage and visual field loss, and remains a leading cause of irreversible blindness. Elevated intraocular pressure (IOP) is a critical risk factor that requires effective management. Emerging research underscores dual roles of bioactive lipid mediators in both IOP regulation, and the modulation of neurodegeneration and neuroinflammation in glaucoma. Bioactive lipids, encompassing eicosanoids, specialized pro-resolving mediators (SPMs), sphingolipids, and endocannabinoids, have emerged as crucial players in these processes, orchestrating inflammation and diverse effects on aqueous humor dynamics and tissue remodeling. Perturbations in these lipid mediators contribute to retinal ganglion cell loss, vascular dysfunction, oxidative stress, and neuroinflammation. Glaucoma management primarily targets IOP reduction via pharmacological agents and surgical interventions, with prostaglandin analogues at the forefront. Intriguingly, additional lipid mediators offer promise in attenuating inflammation and providing neuroprotection. Here we explore these pathways to shed light on their intricate roles, and to unveil novel therapeutic avenues for glaucoma management.

Protective effects of docosahexaenoic acid supplementation on cognitive dysfunction and hippocampal synaptic plasticity impairment induced by early postnatal PM2.5 exposure in young rats

PM2.5 exposure is a challenging environmental issue that is closely related to cognitive development impairment; however, currently, relevant means for prevention and treatment remain lacking. Herein, we determined the preventive effect of docosahexaenoic acid (DHA) supplementation on the neurodevelopmental toxicity induced by PM2.5 exposure. Neonatal rats were divided randomly into three groups: control, PM2.5, and DHA + PM2.5 groups. DHA could ameliorate PM2.5-induced learning and memory dysfunction, as well as reverse the impairment of hippocampal synaptic plasticity, evidenced by enhanced long-term potentiation, recovered synaptic ultrastructure, and increased expression of synaptic proteins. Moreover, DHA increased CREB phosphorylation and BDNF levels and attenuated neuroinflammation and oxidative stress, reflected by lower levels of IBA-1, IL-1β, and IL-6 and increased levels of SOD1 and Nrf2. In summary, our findings demonstrated that supplementation of DHA effectively mitigated the cognitive dysfunction and synaptic plasticity impairment induced by early postnatal exposure to PM2.5. These beneficial effects may be attributed to the upregulation of the CREB/BDNF signaling pathway, as well as the reduction of neuroinflammation and oxidative stress.

The supplementation of a high dose of fish oil during pregnancy and lactation led to an elevation in Mfsd2a expression without any changes in docosahexaenoic acid levels in the retina of healthy 2-month-old mouse offspring

Introduction

During fetal development, the proper development of neural and visual systems relies on the maternal supplementation of omega-3 fatty acids through placental transfer. Pregnant women are strongly advised to augment their diet with additional sources of omega-3, such as fish oil (FO). This supplementation has been linked to a reduced risk of preterm birth, pre-eclampsia, and perinatal depression. Recently, higher doses of omega-3 supplementation have been recommended for pregnant women. Considering that omega-3 fatty acids, particularly docosahexaenoic acid (DHA), play a crucial role in maintaining the delicate homeostasis required for the proper functioning of the retina and photoreceptors the effects of high-dose fish oil (FO) supplementation during pregnancy and lactation on the retina and retinal pigmented epithelium (RPE) in healthy offspring warrant better understanding.

Methods

The fatty acid content and the changes in the expression of the genes regulating cholesterol homeostasis and DHA transport in the retina and RPE were evaluated following the high-dose FO supplementation.

Results

Our study demonstrated that despite the high-dose FO treatment during pregnancy and lactation, the rigorous DHA homeostasis in the retina and RPE of the two-month-old offspring remained balanced. Another significant finding of this study is the increase in the expression levels of major facilitator superfamily domain-containing protein (Mfsd2a), a primary DHA transporter. Mfsd2a also serves as a major regulator of transcytosis during development, and a reduction in Mfsd2a levels poses a major risk for the development of leaky blood vessels.

Conclusion

Impairment of the blood-retinal barrier (BRB) is associated with the development of numerous ocular diseases, and a better understanding of how to manipulate transcytosis in the BRB during development can enhance drug delivery through the BRB or contribute to the repair of central nervous system (CNS) barriers.

Elovanoid-N34 modulates TXNRD1 key in protection against oxidative stress-related diseases

The thioredoxin (TXN) system is an NADPH + H+/FAD redox-triggered effector that sustains homeostasis, bioenergetics, detoxifying drug networks, and cell survival in oxidative stress-related diseases. Elovanoid (ELV)-N34 is an endogenously formed lipid mediator in neural cells from omega-3 fatty acid precursors that modulate neuroinflammation and senescence gene programming when reduction-oxidation (redox) homeostasis is disrupted, enhancing cell survival. Limited proteolysis (LiP) screening of human retinal pigment epithelial (RPE) cells identified TXNRD1 isoforms 2, 3, or 5, the reductase of the TXN system, as an intracellular target of ELV-N34. TXNRD1 silencing confirmed that the ELV-N34 target was isoform 2 or 3. This lipid mediator induces TXNRD1 structure changes that modify the FAD interface domain, leading to its activity modulation. The addition of ELV-N34 decreased membrane and cytosolic TXNRD1 activity, suggesting localizations for the targeted reductase. These results show for the first time that the lipid mediator ELV-N34 directly modulates TXNRD1 activity, underling its protection in several pathologies when uncompensated oxidative stress (UOS) evolves.

Novel Approaches for Elongation of Fish Oils into Very-Long-Chain Polyunsaturated Fatty Acids and Their Enzymatic Interesterification into Glycerolipids

Elongation of the Very-Long-Chain Fatty Acids-4 (ELOVL4) enzyme that is expressed in neuronal tissues, sperm, and testes mediates biosynthesis of very-long-chain polyunsaturated fatty acids (VLC-PUFAs) from dietary long chain PUFAs (LC-PUFAs). The VLC-PUFAs are critical for neuronal and reproductive function. Therefore, mutations in ELOVL4 that affect VLC-PUFA biosynthesis contribute to retinal degenerative diseases including Autosomal Dominant Stargardt-like Macular Dystrophy (STGD3). Recent studies have also shown not only a depletion of retinal VLC-PUFAs with normal aging but also a more significant loss of VLC-PUFAs in donor eyes of patients with age-related macular degeneration (AMD). However, currently, there are no natural sources of VLC-PUFAs to be evaluated as dietary supplements for the attenuation of retinal degeneration in animal models of STGD3. Here, we report the development of a novel chemical approach for elongation of eicosapentaenoic (C20:5 n-3) and docosahexaenoic (C22:6 n-3) acids from fish oils by 6 carbon atoms to make a unique group of VLC-PUFAs, namely all-cis-hexacosa-11,14,17,20,23-pentaenoic acids (C26:5 n-3) and all-cis-octacosa-10,13,16,19,22,25-hexaenoic acids (C28:6 n-3). The three-step elongation approach that we report herein resulted in a good overall yield of up to 20.2%. This more sustainable approach also resulted in improved functional group compatibility and minimal impact on the geometrical integrity of the all-cis double bond system of the VLC-PUFAs. In addition, we also successfully used commercial deep-sea fish oil concentrate as an inexpensive material for the C6 elongation of fish oil LC-PUFAs into VLC-PUFAs, which resulted in the making of gram scales of VLC-PUFAs with an even higher isolation yield of 31.0%. The quality of fish oils and the content of oxidized lipids were key since both strongly affected the activity of the PEPPSI-IPr catalyst and ultimately the yield of coupling reactions. Downstream enzymatic interesterification was used for the first time to prepare structured glycerolipids enriched with VLC-PUFAs that could be evaluated in vivo to determine absorption and transport to target tissues relative to those of the free fatty acid forms. It turned out that in the synthesis of structured triacylglycerols and glycerophospholipids with VLC-PUFAs, the polarity of the immobilized lipase carrier and its humidity were essential.

Review of Eukaryote Cellular Membrane Lipid Composition, with Special Attention to the Fatty Acids

Biological membranes, primarily composed of lipids, envelop each living cell. The intricate composition and organization of membrane lipids, including the variety of fatty acids they encompass, serve a dynamic role in sustaining cellular structural integrity and functionality. Typically, modifications in lipid composition coincide with consequential alterations in universally significant signaling pathways. Exploring the various fatty acids, which serve as the foundational building blocks of membrane lipids, provides crucial insights into the underlying mechanisms governing a myriad of cellular processes, such as membrane fluidity, protein trafficking, signal transduction, intercellular communication, and the etiology of certain metabolic disorders. Furthermore, comprehending how alterations in the lipid composition, especially concerning the fatty acid profile, either contribute to or prevent the onset of pathological conditions stands as a compelling area of research. Hence, this review aims to meticulously introduce the intricacies of membrane lipids and their constituent fatty acids in a healthy organism, thereby illuminating their remarkable diversity and profound influence on cellular function. Furthermore, this review aspires to highlight some potential therapeutic targets for various pathological conditions that may be ameliorated through dietary fatty acid supplements. The initial section of this review expounds on the eukaryotic biomembranes and their complex lipids. Subsequent sections provide insights into the synthesis, membrane incorporation, and distribution of fatty acids across various fractions of membrane lipids. The last section highlights the functional significance of membrane-associated fatty acids and their innate capacity to shape the various cellular physiological responses.

Rod-specific downregulation of omega-3 very-long-chain polyunsaturated fatty acid pathway in age-related macular degeneration

Docosahexaenoic acid (DHA; 22:6) plays a key role in vision and is the precursor for very-long-chain polyunsaturated fatty acids (VLC-PUFAs). The release of 32- and 34-carbon VLC-PUFAs and DHA from sn-1 and sn-2 of phosphatidylcholine (PC) leads to the synthesis of cell-survival mediators, the elovanoids (ELVs) and neuroprotectin D1 (NPD1), respectively. Macula and periphery from age-related macular degeneration (AMD) donor retinas were assessed for the availability of DHA-related lipids by LC-MS/MS-based lipidomic analysis and MALDI-molecular imaging. We found reduced retina DHA and VLC-PUFA pathways to synthesize omega-3 ELVs from precursors that likely resulted in altered disks and photoreceptor loss. Additionally, we compared omega-3 (n-3) fatty acid with DHA (22:6) and omega-6 (n-6) fatty acid with arachidonic acid (AA; 20:4) pathways. n-3 PC(22:6/22:6, 44:12) and n-6 PC(20:4/20:4, 40:8) showed differences among male/female, macula/periphery, and normal/AMD retinas. Periphery of AMD retina males increased 44:12 abundance, while normal females increased 40:8 (all macula had an upward 40:8 tendency). We also showed that female AMD switched from n-3 to n-6 fatty acids; most changes in AMD occurred in the periphery of female AMD retinas. DHA and VLC-PUFA release from PCs leads to conversion in pro-survival NPD1 and ELVs. The loss of the neuroprotective precursors of ELVs in the retina periphery from AMD facilitates uncompensated stress and cell loss. In AMD, the female retina loses peripheral rods VLC-PUFAs to about 33% less than in males limiting ELV formation and its protective bioactivity.

Retina and RPE lipid profile changes linked with ABCA4 associated Stargardt's maculopathy

Stargardt maculopathy, caused predominantly by mutations in the ABCA4 gene, is characterized by an accumulation of non-degradable visual pigment derivative, lipofuscin, in the retinal pigment epithelium (RPE) - resulting in RPE atrophy. RPE is a monolayer tissue located adjacent to retinal photoreceptors and regulates their health and functioning; RPE atrophy triggers photoreceptor cell death and vision loss in Stargardt patients. Previously, ABCA4 mutations in photoreceptors were thought to be the major contributor to lipid homeostasis defects in the eye. Recently, we demonstrated that ABCA4 loss of function in the RPE leads to cell-autonomous lipid homeostasis defects. Our work underscores that an incomplete understanding of lipid metabolism and lipid-mediated signaling in the retina and RPE are potential causes for lacking treatments for this disease. Here we report altered lipidomic in mouse and human Stargardt models. This work provides the basis for therapeutics that aim to restore lipid homeostasis in the retina and the RPE.

Polyunsaturated Fatty Acids: Conversion to Lipid Mediators, Roles in Inflammatory Diseases and Dietary Sources

Polyunsaturated fatty acids (PUFAs) are important components of the diet of mammals. Their role was first established when the essential fatty acids (EFAs) linoleic acid and α-linolenic acid were discovered nearly a century ago. However, most of the biochemical and physiological actions of PUFAs rely on their conversion to 20C or 22C acids and subsequent metabolism to lipid mediators. As a generalisation, lipid mediators formed from n-6 PUFAs are pro-inflammatory while those from n-3 PUFAs are anti-inflammatory or neutral. Apart from the actions of the classic eicosanoids or docosanoids, many newly discovered compounds are described as Specialised Pro-resolving Mediators (SPMs) which have been proposed to have a role in resolving inflammatory conditions such as infections and preventing them from becoming chronic. In addition, a large group of molecules, termed isoprostanes, can be generated by free radical reactions and these too have powerful properties towards inflammation. The ultimate source of n-3 and n-6 PUFAs are photosynthetic organisms which contain Δ-12 and Δ-15 desaturases, which are almost exclusively absent from animals. Moreover, the EFAs consumed from plant food are in competition with each other for conversion to lipid mediators. Thus, the relative amounts of n-3 and n-6 PUFAs in the diet are important. Furthermore, the conversion of the EFAs to 20C and 22C PUFAs in mammals is rather poor. Thus, there has been much interest recently in the use of algae, many of which make substantial quantities of long-chain PUFAs or in manipulating oil crops to make such acids. This is especially important because fish oils, which are their main source in human diets, are becoming limited. In this review, the metabolic conversion of PUFAs into different lipid mediators is described. Then, the biological roles and molecular mechanisms of such mediators in inflammatory diseases are outlined. Finally, natural sources of PUFAs (including 20 or 22 carbon compounds) are detailed, as well as recent efforts to increase their production.

Therapeutic Role of ELOVL in Neurological Diseases

Fatty acids play an important role in controlling the energy balance of mammals. De novo lipogenesis also generates a significant amount of lipids that are endogenously produced in addition to their ingestion. Fatty acid elongation beyond 16 carbons (palmitic acid), which can lead to the production of very long chain fatty acids (VLCFA), can be caused by the rate-limiting condensation process. Seven elongases, ELOVL1-7, have been identified in mammals and each has a unique substrate specificity. Researchers have recently developed a keen interest in the elongation of very long chain fatty acids protein 1 (ELOVL1) enzyme as a potential treatment for a variety of diseases. A number of neurological disorders directly or indirectly related to ELOVL1 involve the elongation of monounsaturated (C20:1 and C22:1) and saturated (C18:0-C26:0) acyl-CoAs. VLCFAs and ELOVL1 have a direct impact on the neurological disease. Other neurological symptoms such as ichthyotic keratoderma, spasticity, and hypomyelination have also been linked to the major enzyme (ELOVL1). Recently, ELOVL1 has also been heavily used to treat a number of diseases. The current review focuses on in-depth unique insights regarding the role of ELOVL1 as a therapeutic target and associated neurological disorders.

Lipid Profiling in Alzheimer's Disease

The human brain is the organ with the most lipids after adipose tissues. The rich heterogeneity of the neural lipidome is being actively investigated with the aim of shedding new light into the physiological and pathological roles these compounds play in the brain. This is particularly important for the study of increasingly common neurodegenerative pathologies, such as Alzheimer's disease (AD), whose underlying mechanisms are still insufficiently understood and for which there is no cure. The present text dives into the current knowledge of the lipid composition of the brain, with a particular focus on the application of lipid profiling to AD research.

An SPM-Enriched Marine Oil Supplement Shifted Microglia Polarization toward M2, Ameliorating Retinal Degeneration in rd10 Mice

Retinitis pigmentosa (RP) is the most common inherited retinal dystrophy causing progressive vision loss. It is accompanied by chronic and sustained inflammation, including M1 microglia activation. This study evaluated the effect of an essential fatty acid (EFA) supplement containing specialized pro-resolving mediators (SPMs), on retinal degeneration and microglia activation in rd10 mice, a model of RP, as well as on LPS-stimulated BV2 cells. The EFA supplement was orally administered to mice from postnatal day (P)9 to P18. At P18, the electrical activity of the retina was examined by electroretinography (ERG) and innate behavior in response to light were measured. Retinal degeneration was studied via histology including the TUNEL assay and microglia immunolabeling. Microglia polarization (M1/M2) was assessed by flow cytometry, qPCR, ELISA and histology. Redox status was analyzed by measuring antioxidant enzymes and markers of oxidative damage. Interestingly, the EFA supplement ameliorated retinal dysfunction and degeneration by improving ERG recording and sensitivity to light, and reducing photoreceptor cell loss. The EFA supplement reduced inflammation and microglia activation attenuating M1 markers as well as inducing a shift to the M2 phenotype in rd10 mouse retinas and LPS-stimulated BV2 cells. It also reduced oxidative stress markers of lipid peroxidation and carbonylation. These findings could open up new therapeutic opportunities based on resolving inflammation with oral supplementation with SPMs such as the EFA supplement.

Dietary fish oil increases catalase activity in patients with probable Alzheimer's disease

Background: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the presence of neuritic plaques and neurofibrillary tangles that finally result in synaptic and neuronal loss. Oxidative stress accompanies pathological changes in AD. Objective: to assess the efficacy of dietary omega 3 polyunsaturated fatty acids supplementation on the levels of proteins oxidation, hydroperoxides and enzymatic activities of catalase and superoxide dismutase in AD patients. Methods: clinical, controlled, randomized, double-blind trial. Patients consumed fish oil or placebo for one year. Oxidative stress markers were assessed in plasma using spectrophotometric methods. Results: carbonyl groups in proteins and hydroperoxides in plasma have similar values in both treatment groups at the beginning of the study. At six and 12 months of treatment, these values decreased significantly in the fish oil group, while in the placebo group no changes were observed in both oxidative stress markers. Catalase activity increased significantly at six and twelve months after treatment in patients treated with fish oil. While the superoxide dismutase activity was not modified in both study groups. Conclusions: patients who consume omega 3 polyunsaturated fatty acids at a stable dose of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) show decreased oxidation of proteins and lipids in plasma. In addition, an increase in catalase activity was detected. Thus, the presented data warrants further studies evaluating the antioxidant effect of omega 3 polyunsaturated fatty acids.

Lipid metabolism and storage in neuroglia: role in brain development and neurodegenerative diseases

The importance of neuroglia in maintaining normal brain function under physiological and pathological conditions has been supported by growing evidence in recent years. The most important issues regarding glial metabolism and function include the cooperation between glial populations and neurons, morphological and functional changes in pathological states, and the role in the onset and progression of neurodegenerative diseases. Although lipid accumulation and further lipid droplet production in neurodegenerative disease brain models have been observed for a long time, the dynamic development of brain lipid droplet research in recent years suggests its role in the development and progression of neurodegenerative diseases was previously underestimated. First recognized as organelles of lipid storage, lipid droplets (LDs) have emerged as an important organelle in metabolic diseases, inflammation, and host defense. Dynamic changes in lipid metabolism within neurons and glial cells resulting in lipid accumulation and lipid droplet formation are present in brain models of various neurodegenerative diseases, yet their role in the brain remains largely unexplored. This paper first reviews the metabolism and accumulation of several major lipids in the brain and discusses the regulation of lipid accumulation in different types of brain cells. We explore the potential role of intracellular lipid accumulation in the pathogenesis of neurodegeneration, starting from lipid metabolism and LDs biogenesis in glial cells, and discuss several pathological factors that promote lipid droplet formation, mainly focusing on oxidative stress, energy metabolism and glial cell-neuron coupling, which are closely related to the etiology and progression of neurodegenerative diseases. Finally, the directions and challenges of intracellular lipid metabolism in glial cells in neurodegeneration are discussed.

A Review of Oxylipins in Alzheimer's Disease and Related Dementias (ADRD): Potential Therapeutic Targets for the Modulation of Vascular Tone and Inflammation

There is now a convincing body of evidence from observational studies that the majority of modifiable Alzheimer's disease and related dementia (ADRD) risk factors are vascular in nature. In addition, the co-existence of cerebrovascular disease with AD is more common than AD alone, and conditions resulting in brain ischemia likely promote detrimental effects of AD pathology. Oxylipins are a class of bioactive lipid mediators derived from the oxidation of long-chain polyunsaturated fatty acids (PUFAs) which act as modulators of both vascular tone and inflammation. In vascular cognitive impairment (VCI), there is emerging evidence that oxylipins may have both protective and detrimental effects on brain structure, cognitive performance, and disease progression. In this review, we focus on oxylipin relationships with vascular and inflammatory risk factors in human studies and animal models pertinent to ADRD. In addition, we discuss future research directions with the potential to impact the trajectory of ADRD risk and disease progression.

Polyunsaturated fatty acids and fatty acid-derived lipid mediators: Recent advances in the understanding of their biosynthesis, structures, and functions

Polyunsaturated fatty acids (PUFAs) are structural components of membrane phospholipids, and influence cellular function via effects on membrane properties, and also by acting as a precursor pool for lipid mediators. These lipid mediators are formed via activation of pathways involving at least one step of dioxygen-dependent oxidation, and are consequently called oxylipins. Their biosynthesis can be either enzymatically-dependent, utilising the promiscuous cyclooxygenase, lipoxygenase, or cytochrome P450 mixed function oxidase pathways, or nonenzymatic via free radical-catalyzed pathways. The oxylipins include the classical eicosanoids, comprising prostaglandins, thromboxanes, and leukotrienes, and also more recently identified lipid mediators. With the advent of new technologies there is growing interest in identifying these different lipid mediators and characterising their roles in health and disease. This review brings together contributions from some of those at the forefront of research into lipid mediators, who provide brief introductions and summaries of current understanding of the structure and functions of the main classes of nonclassical oxylipins. The topics covered include omega-3 and omega-6 PUFA biosynthesis pathways, focusing on the roles of the different fatty acid desaturase enzymes, oxidized linoleic acid metabolites, omega-3 PUFA-derived specialized pro-resolving mediators, elovanoids, nonenzymatically oxidized PUFAs, and fatty acid esters of hydroxy fatty acids.

Long-Chain Polyunsaturated Fatty Acids and Their Metabolites Regulate Inflammation in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a blinding eye disease, whose incidence strongly increases with ages. The etiology of AMD is complex, including aging, abnormal lipid metabolism, chronic inflammation and oxidative stress. Long-chain polyunsaturated fatty acids (LCPUFA) are essential for ocular structures and functions. This review summarizes the regulatory effects of LCPUFA on inflammation in AMD. LCPUFA are related to aging, autophagy and chronic inflammation. They are metabolized to pro- and anti-inflammatory metabolites by various enzymes. These metabolites stimulate inflammation in response to oxidative stress, causing innate and acquired immune responses. This review also discusses the possible clinical applications, which provided novel targets for the prevention and treatment of AMD and other age-related diseases.

Changes in the level of fatty acids in the brain of rats during memory acquisition

Memory acquisition is accompanied by many cellular and molecular processes, and it is not always clear what role they play. Fatty acids (FAs) are known to be important for cognitive functions, but the details of their involvement in memory processes remain unknown. We investigated FAs in the prefrontal cortex and hippocampus of rats trained to perform a task with food reinforcement. The learning consisted of two training sessions, each of which included 10 trials. The results showed that such training altered individual FAs in the brains. The most significant changes were in the prefrontal cortex, where an increase in the level of many FAs occurred, especially after the second training session: palmitic (16:0), stearic (18:0), docosahexaenoic (22:6, n-3), arachidonic (22:4, n-6), docosapentaenoic (22:5, n-6) acids. Changes in the fatty acid level after training in rats were detected only in the left hippocampus, where the levels of palmitic, docosapentaenoic, and docosahexaenoic acids changed. The changes in the right hippocampus were not significant. In both the prefrontal cortex and the left hippocampus, 72 h after training, all FAs returned to control levels. We believe that the main role of a reversible increase in FA levels during memory acquisition is to support and protect cellular processes involved in memory acquisition. Consolidation of memory traces, which occurs mainly in the neocortex, requires protection from external influences, to which FAs makes a significant contribution. They are able to improve neuronal plasticity, enhance local blood flow, improve mitochondrial processes, and suppress pro-inflammatory signals.

Elovanoids Counteract Inflammatory Signaling, Autophagy, Endoplasmic Reticulum Stress, and Senescence Gene Programming in Human Nasal Epithelial Cells Exposed to Allergens

To contribute to further understanding the cellular and molecular complexities of inflammatory-immune responses in allergic disorders, we have tested the pro-homeostatic elovanoids (ELV) in human nasal epithelial cells (HNEpC) in culture challenged by several allergens. ELV are novel bioactive lipid mediators synthesized from the omega-3 very-long-chain polyunsaturated fatty acids (VLC-PUFA,n-3). We ask if: (a) several critical signaling events that sustain the integrity of the human nasal epithelium and other organ barriers are perturbed by house dust mites (HDM) and other allergens, and (b) if ELV would participate in beneficially modulating these events. HDM is a prevalent indoor allergen that frequently causes allergic respiratory diseases, including allergic rhinitis and allergic asthma, in HDM-sensitized individuals. Our study used HNEpC as an in vitro model to study the effects of ELV in counteracting HDM sensitization resulting in inflammation, endoplasmic reticulum (ER) stress, autophagy, and senescence. HNEpC were challenged with the following allergy inducers: LPS, poly(I:C), or Dermatophagoides farinae plus Dermatophagoides pteronyssinus extract (HDM) (30 µg/mL), with either phosphate-buffered saline (PBS) (vehicle) or ELVN-34 (500 nM). Results show that ELVN-34 promotes cell viability and reduces cytotoxicity upon HDM sensitization of HNEpC. This lipid mediator remarkably reduces the abundance of pro-inflammatory cytokines and chemokines IL-1β, IL-8, VEGF, IL-6, CXCL1, CCL2, and cell adhesion molecule ICAM1 and restores the levels of the pleiotropic anti-inflammatory IL-10. ELVN-34 also lessens the expression of senescence gene programming as well as of gene transcription engaged in pro-inflammatory responses. Our data also uncovered that HDM triggered the expression of key genes that drive autophagy, unfolded protein response (UPR), and matrix metalloproteinases (MMP). ELVN-34 has been shown to counteract these effects effectively. Together, our data reveal a novel, pro-homeostatic, cell-protective lipid-signaling mechanism in HNEpC as potential therapeutic targets for allergies.

Dynamic lipid turnover in photoreceptors and retinal pigment epithelium throughout life

The retinal pigment epithelium-photoreceptor interphase is renewed each day in a stunning display of cellular interdependence. While photoreceptors use photosensitive pigments to convert light into electrical signals, the RPE supports photoreceptors in their function by phagocytizing shed photoreceptor tips, regulating the blood retina barrier, and modulating inflammatory responses, as well as regenerating the 11-cis-retinal chromophore via the classical visual cycle. These processes involve multiple protein complexes, tightly regulated ligand-receptors interactions, and a plethora of lipids and protein-lipids interactions. The role of lipids in maintaining a healthy interplay between the RPE and photoreceptors has not been fully delineated. In recent years, novel technologies have resulted in major advancements in understanding several facets of this interplay, including the involvement of lipids in phagocytosis and phagolysosome function, nutrient recycling, and the metabolic dependence between the two cell types. In this review, we aim to integrate the complex role of lipids in photoreceptor and RPE function, emphasizing the dynamic exchange between the cells as well as discuss how these processes are affected in aging and retinal diseases.

Converging evidence in support of omega-3 polyunsaturated fatty acids as a potential therapy for Huntington's disease symptoms

Huntington's disease (HD) is a genetic, inexorably fatal neurodegenerative disease. Patient average survivability is up to 20 years after the onset of symptoms. Those who suffer from the disease manifest motor, cognitive, and psychiatric impairments. There is indirect evidence suggesting that omega-3 polyunsaturated fatty acids (ω-3 PUFA) could have alleviating effects on most of HD symptoms. These include beneficial effects against cachexia and weight loss, decrease of cognitive impairment over time, and improvement of psychiatric symptoms such as depression and irritability. Furthermore, there is a positive correlation between consumption of ω-3 PUFAs in diets and prevalence of HD, as well as direct effects on the disease via release of serotonin. Unfortunately, to date, very few studies have examined the effects of ω-3 PUFAs in HD, both on the symptoms and on disease progression. This paper reviews evidence in the literature suggesting that ω-3 PUFAs can be used in neurodegenerative disorders. This information can be extrapolated to support further research of ω-3 PUFAs and their potential use for HD treatment.

Bioactive lipids and their metabolism: new therapeutic opportunities for Parkinson's disease

Parkinson's disease (PD) is a neurological disorder characterized by motor dysfunction, which can also be associated with non-motor symptoms. Its pathogenesis is thought to stem from a loss of dopaminergic neurons in the substantia nigra pars compacta and the formation of Lewy bodies containing aggregated α-synuclein. Recent works suggested that lipids might play a pivotal role in the pathophysiology of PD. In particular, the so-called "bioactive" lipids whose changes in the concentration may lead to functional consequences and affect many pathophysiological processes, including neuroinflammation, are closely related to PD in terms of symptoms, disease progression, and incidence. This study aimed to explore the molecular metabolism and physiological functions of bioactive lipids, such as fatty acids (mainly unsaturated fatty acids), eicosanoids, endocannabinoids, oxysterols, representative sphingolipids, diacylglycerols, and lysophosphatidic acid, in the development of PD. The knowledge of bioactive lipids in PD gained through preclinical and clinical studies is expected to improve the understanding of disease pathogenesis and provide novel therapeutic avenues.

Moderate blood alcohol and brain neurovulnerability: Selective depletion of calcium-independent phospholipase A2, omega-3 docosahexaenoic acid, and its synaptamide derivative as a potential harbinger of deficits in anti-inflammatory reserve

BACKGROUND

Repetitive, highly elevated blood alcohol (ethanol) concentrations (BACs) of 350 to 450 mg/dl over several days cause brain neurodegeneration and coincident neuroinflammation in adult rats localized in the hippocampus (HC), temporal cortex (especially the entorhinal cortex; ECX), and olfactory bulb (OB). The profuse neuroinflammation involves microgliosis, increased proinflammatory cytokines, and elevations of Ca+2 -dependent phospholipase A2 (cPLA2) and secretory PLA2 (sPLA2), which both mobilize proinflammatory ω-6 arachidonic acid (ARA). In contrast, Ca+2 -independent PLA2 (iPLA2) and anti-inflammatory ω-3 docosahexaenoic acid (DHA), a polyunsaturated fatty acid regulated primarily by iPLA2, are diminished. Furthermore, supplemented DHA exerts neuroprotection. Given uncertainties about the possible effects of lower circulating BACs that are common occurring during short- term binges, we examined how moderate BACs affected the above inflammatory events, and the impact of supplemented DHA.

METHODS AND RESULTS

Young adult male rats sustaining upper-moderate BACs (~150 mg/dl) from once-daily alcohol intubations were sacrificed with appropriate controls after 1 week. The HC, ECX and OB were quantitatively examined using immunoblotting, neurodegeneration staining, and lipidomics assays. Whereas neurodegeneration, increases in cPLA2 IVA, sPLA2 IIA, and ARA, and microglial activation were not detected, the HC and ECX regions demonstrated significantly reduced iPLA2 levels. Levels of DHA and synaptamide, its anti-inflammatory N-docosahexaenoylethanolamide derivative, also were lower in HC, and DHA supplementation prevented the iPLA2 decrements in HC. Additionally, adult mice maintaining upper-moderate BACs from limited alcohol binges had reduced midbrain iPLA2 levels.

CONCLUSIONS

The apparently selective depletion by moderate BACs of the metabolically linked anti-inflammatory triad of hippocampal iPLA2, DHA, and synaptamide, and of iPLA2 in the ECX, potentially indicates an unappreciated deficit in brain anti-inflammatory reserve that may be a harbinger of regional neurovulnerability.

Circadian Regulation and Clock-Controlled Mechanisms of Glycerophospholipid Metabolism from Neuronal Cells and Tissues to Fibroblasts

Along evolution, living organisms developed a precise timekeeping system, circadian clocks, to adapt life to the 24-h light/dark cycle and temporally regulate physiology and behavior. The transcriptional molecular circadian clock and metabolic/redox oscillator conforming these clocks are present in organs, tissues, and even in individual cells, where they exert circadian control over cellular metabolism. Disruption of the molecular clock may cause metabolic disorders and higher cancer risk. The synthesis and degradation of glycerophospholipids (GPLs) is one of the most highly regulated metabolisms across the 24-h cycle in terms of total lipid content and enzyme expression and activity in the nervous system and individual cells. Lipids play a plethora of roles (membrane biogenesis, energy sourcing, signaling, and the regulation of protein-chromatin interaction, among others), making control of their metabolism a vital checkpoint in the cellular organization of physiology. An increasing body of evidence clearly demonstrates an orchestrated and sequential series of events occurring in GPL metabolism across the 24-h day in diverse retinal cell layers, immortalized fibroblasts, and glioma cells. Moreover, the clock gene Per1 and other circadian-related genes are tightly involved in the regulation of GPL synthesis in quiescent cells. However, under proliferation, the metabolic oscillator continues to control GPL metabolism of brain cancer cells even after molecular circadian clock disruption, reflecting the crucial role of the temporal metabolism organization in cell preservation. The aim of this review is to examine the control exerted by circadian clocks over GPL metabolism, their synthesizing enzyme expression and activities in normal and tumorous cells of the nervous system and in immortalized fibroblasts.

Combined Therapy With Avastin, a PAF Receptor Antagonist and a Lipid Mediator Inhibited Glioblastoma Tumor Growth

Glioblastoma multiforme (GBM) is an aggressive, highly proliferative, invasive brain tumor with a poor prognosis and low survival rate. The current standard of care for GBM is chemotherapy combined with radiation following surgical intervention, altogether with limited efficacy, since survival averages 18 months. Improvement in treatment outcomes for patients with GBM requires a multifaceted approach due to the dysregulation of numerous signaling pathways. Recently emerging therapies to precisely modulate tumor angiogenesis, inflammation, and oxidative stress are gaining attention as potential options to combat GBM. Using a mouse model of GBM, this study aims to investigate Avastin (suppressor of vascular endothelial growth factor and anti-angiogenetic treatment), LAU-0901 (a platelet-activating factor receptor antagonist that blocks pro-inflammatory signaling), Elovanoid; ELV, a novel pro-homeostatic lipid mediator that protects neural cell integrity and their combination as an alternative treatment for GBM. Female athymic nude mice were anesthetized with ketamine/xylazine, and luciferase-modified U87MG tumor cells were stereotactically injected into the right striatum. On post-implantation day 13, mice received one of the following: LAU-0901, ELV, Avastin, and all three compounds in combination. Bioluminescent imaging (BLI) was performed on days 13, 20, and 30 post-implantation. Mice were perfused for ex vivo MRI on day 30. Bioluminescent intracranial tumor growth percentage was reduced by treatments with LAU-0901 (43%), Avastin (77%), or ELV (86%), individually, by day 30 compared to saline treatment. In combination, LAU-0901/Avastin, ELV/LAU-0901, or ELV/Avastin had a synergistic effect in decreasing tumor growth by 72, 92, and 96%, respectively. Additionally, tumor reduction was confirmed by MRI on day 30, which shows a decrease in tumor volume by treatments with LAU-0901 (37%), Avastin (67%), or ELV (81.5%), individually, by day 30 compared to saline treatment. In combination, LAU-0901/Avastin, ELV/LAU-0901, or ELV/Avastin had a synergistic effect in decreasing tumor growth by 69, 78.7, and 88.6%, respectively. We concluded that LAU-0901 and ELV combined with Avastin exert a better inhibitive effect in GBM progression than monotherapy. To our knowledge, this is the first study that demonstrates the efficacy of these novel therapeutic regimens in a model of GBM and may provide the basis for future therapeutics in GBM patients.

The expression of ELOVL4, repressed by MYCN, defines neuroblastoma patients with good outcome

Cancer cells exhibit dysregulation of critical genes including those involved in lipid biosynthesis, with subsequent defects in metabolism. Here, we show that ELOngation of Very Long chain fatty acids protein 4 (ELOVL4), a rate-limiting enzyme in the biosynthesis of very-long polyunsaturated fatty acids (n-3, ≥28 C), is expressed and transcriptionally repressed by the oncogene MYCN in neuroblastoma cells. In keeping, ELOVL4 positively regulates neuronal differentiation and lipids droplets accumulation in neuroblastoma cells. At the molecular level we found that MYCN binds to the promoter of ELOVL4 in close proximity to the histone deacetylases HDAC1, HDAC2, and the transcription factor Sp1 that can cooperate in the repression of ELOVL4 expression. Accordingly, in vitro differentiation results in an increase of fatty acid with 34 carbons with 6 double bonds (FA34:6); and when MYCN is silenced, FA34:6 metabolite is increased compared with the scrambled. In addition, analysis of large neuroblastoma datasets revealed that ELOVL4 expression is highly expressed in localized clinical stages 1 and 2, and low in high-risk stages 3 and 4. More importantly, high expression of ELOVL4 stratifies a subsets of neuroblastoma patients with good prognosis. Indeed, ELOVL4 expression is a marker of better overall clinical survival also in MYCN not amplified patients and in those with neuroblastoma-associated mutations. In summary, our findings indicate that MYCN, by repressing the expression of ELOVL4 and lipid metabolism, contributes to the progression of neuroblastoma.

It Is Time for an Oil Change: Polyunsaturated Fatty Acids and Human Health

Polyunsaturated fatty acids (PUFAs) such as docosahexaneoic acid (DHA) and eicosapentaneoic acid (EPA), play a critical role in a variety of neuronal functions, including facilitating neuronal growth and differentiation, increasing the density of the neuritic network, modulating cell membrane fluidity, regulating intracellular signaling and gene expression, and exhibiting antioxidant characteristics. Dietary DHA is selectively enriched and actively retained in the central nervous system, mainly in synaptic membranes, dendrites, and photoreceptors. In this review, we highlight the myriad roles of PUFAs in brain function and human health. Diets rich in DHA are inversely proportional to cognitive decline and incidence of neurodegenerative disorders. Conversely, diets deficient in DHA impair the proper development of brain and the visual system in children and increase risk of brain disorders in the elderly. Finally, DHA and EPA have been shown to reduce inflammation and may prove to be beneficial in reducing the severity of the SARS-COVID infection.

Mental Health in Childhood and Adolescence: The Role of Polyunsaturated Fatty Acids

There is increasing awareness of the importance of polyunsaturated fatty acids (PUFAs) for optimal brain development and function. In recent decades, researchers have confirmed the central role of PUFAs in a variety of patho-physiological processes. These agents modulate the mechanisms of brain cell signalling including the dopaminergic and serotonergic pathways. Therefore, nutritional insufficiencies of PUFAs may have adverse effects on brain development and developmental outcomes. The role of n-3 PUFAs has been studied in several psychiatric disorders in adulthood: schizophrenia, major depression, bipolar disorder, anxiety disorders, obsessive-compulsive disorder, post-traumatic stress disorder, attention deficit hyperactivity disorder (ADHD), autism spectrum disorders, eating disorders, substance use disorder, and borderline personality disorder. In contrast to the great number of studies conducted in adults, there are only limited data on the effects of n-3 PUFA supplementation in children and adolescents who suffer from mental disorders or show a high risk of developing psychiatric disorders. The aim of this review is to provide a complete and updated account of the available evidence of the impact of polyunsaturated fatty acids on developmental psychopathology in children and adolescents and the effect of fatty acid supplementation during developmental milestones, particularly in high-risk populations of children with minimal but detectable signs or symptoms of mental disorders.

Potential role of hepatic lipase in the accretion of docosahexaenoic acid (DHA) by the brain

DHA (docosahexaenoic acid) is an essential fatty acid that is required for the normal development and function of the brain. Because of its inability to synthesize adequate amounts of DHA from the precursors, the brain has to acquire DHA from plasma through the blood brain barrier (BBB). Recent studies demonstrated the presence of a transporter at the BBB that specifically transports DHA into the brain in the form of lysophosphatidylcholine (LPC-DHA). However, the mechanism by which LPC-DHA is generated in the plasma is not known. Our previous studies showed that there are at least three different enzymes - lecithin cholesterol acyltransferase (LCAT), endothelial lipase (EL), and hepatic lipase (HL), which can generate LPC-DHA from sn-2 DHA phosphatidylcholine. Here we determined the relative contributions of these enzymes in the delivery of DHA to the brain by measuring the brain DHA levels in the mice deficient in each of these enzymes. The results show that the brain DHA levels of LCAT-deficient mice or EL-deficient mice were not significantly lower than those of their littermates. However, brain DHA was significantly decreased in HL deficient mice (13.5% of total fatty acids) compared to their littermates (17.1%) (p < 0.002), and further decreased to 8.3% of total fatty acids in mice deficient in both HL and EL. These results suggest that HL activity may be the major source for the generation of LPC-DHA in the plasma necessary for transport into the brain, and EL might contribute to this process in the absence of HL.

Effects of Dietary n-3 and n-6 Polyunsaturated Fatty Acids in Inflammation and Cancerogenesis

The dietary recommendation encourages reducing saturated fatty acids (SFA) in diet and replacing them with polyunsaturated fatty acids (PUFAs) n-3 (omega-3) and n-6 (omega-6) to decrease the risk of metabolic disturbances. Consequently, excessive n-6 PUFAs content and high n-6/n-3 ratio are found in Western-type diet. The importance of a dietary n-6/n-3 ratio to prevent chronic diseases is linked with anti-inflammatory functions of linolenic acid (ALA, 18:3n-3) and longer-chain n-3 PUFAs. Thus, this review provides an overview of the role of oxylipins derived from n-3 PUFAs and oxylipins formed from n-6 PUFAs on inflammation. Evidence of PUFAs' role in carcinogenesis was also discussed. In vitro studies, animal cancer models and epidemiological studies demonstrate that these two PUFA groups have different effects on the cell growth, proliferation and progression of neoplastic lesions.

ELV-N32 and RvD6 isomer decrease pro-inflammatory cytokines, senescence programming, ACE2 and SARS-CoV-2-spike protein RBD binding in injured cornea

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection that causes coronavirus disease 2019 (COVID-19) has resulted in a pandemic affecting the most vulnerable in society, triggering a public health crisis and economic collapse around the world. Effective treatments to mitigate this viral infection are needed. Since the eye is a route of virus entrance, we use an in vivo rat model of corneal inflammation as well as human corneal epithelial cells (HCEC) in culture challenged with IFNγ as models of the eye surface to study this issue. We explore ways to block the receptor-binding domain (RBD) of SARS-CoV-2 Spike (S) protein to angiotensin-converting enzyme 2 (ACE2). We found that the lipid mediators, elovanoid (ELV)-N32 or Resolvin D6-isomer (RvD6i) decreased the expression of the ACE2 receptor, furin, and integrins in damaged corneas or IFNγ-stimulated HCEC. There was also a concomitant decrease in the binding of Spike RBD with the lipid treatments. Using RNA-seq analysis, we uncovered that the lipid mediators also attenuated the expression of pro-inflammatoy cytokines participating in hyper-inflammation and senescence programming. Thus, the bioactivity of these lipid mediators will contribute to open therapeutic avenues to counteract virus attachment and entrance to the body.

Decrease in DHA and other fatty acids correlates with photoreceptor degeneration in retinitis pigmentosa

Fatty acids, and especially docosahexaenoic acid (DHA), are essential for photoreceptor cell integrity and are involved in the phototransduction cascade. In this study, we analyzed the changes in the fatty acid profile in the retina of the rd10 mouse, model of retinitis pigmentosa, in order to identify potential risk factors for retinal degeneration and possible therapeutic approaches. Fatty acids from C57BL/6J and rd10 mouse retinas were extracted with Folch's method and analyzed by gas chromatography/mass spectrometry. Changes in retinal morphology were evaluated by immunohistochemistry. The rd10 mouse retina showed a decreased number of photoreceptor rows and alterations in photoreceptor morphology compared to C57BL/6J mice. The total amount of fatty acids dropped by 29.4% in the dystrophic retinas compared to C57BL/6J retinas. A positive correlation was found between the retinal content of specific fatty acids and the number of photoreceptor rows. We found that the amount of several short-chain and long-chain saturated fatty acids, as well as monounsaturated fatty acids, decreased in the retina of rd10 mice. Moreover, the content of the n-6 polyunsaturated fatty acid arachidonic acid and the n-3 polyunsaturated DHA decreased markedly in the dystrophic retina. The fall of DHA was more pronounced, hence the n-6/n-3 ratio was significantly increased in the diseased retina. The content of specific fatty acids in the retina decreased with photoreceptor degeneration in retinitis pigmentosa mice, with a remarkable reduction in DHA and other saturated and unsaturated fatty acids. These fatty acids could be essential for photoreceptor cell viability, and they should be evaluated for the design of therapeutical strategies and nutritional supplements.

Elovanoids downregulate SARS-CoV-2 cell-entry, canonical mediators and enhance protective signaling in human alveolar cells

The pro-homeostatic lipid mediators elovanoids (ELVs) attenuate cell binding and entrance of the SARS-CoV-2 receptor-binding domain (RBD) as well as of the SARS-CoV-2 virus in human primary alveoli cells in culture. We uncovered that very-long-chain polyunsaturated fatty acid precursors (VLC-PUFA, n-3) activate ELV biosynthesis in lung cells. Both ELVs and their precursors reduce the binding to RBD. ELVs downregulate angiotensin-converting enzyme 2 (ACE2) and enhance the expression of a set of protective proteins hindering cell surface virus binding and upregulating defensive proteins against lung damage. In addition, ELVs and their precursors decreased the signal of spike (S) protein found in SARS-CoV-2 infected cells, suggesting that the lipids curb viral infection. These findings open avenues for potential preventive and disease-modifiable therapeutic approaches for COVID-19.

Retina Metabolism and Metabolism in the Pigmented Epithelium: A Busy Intersection

The outer retina is nourished from the choroid, a capillary bed just inside the sclera. O₂, glucose, and other nutrients diffuse out of the choroid and then filter through a monolayer of retinal pigment epithelium (RPE) cells to fuel the retina. Recent studies of energy metabolism have revealed striking differences between retinas and RPE cells in the ways that they extract energy from fuels. The purpose of this review is to suggest and evaluate the hypothesis that the retina and RPE have complementary metabolic roles that make them depend on each other for survival and for their abilities to perform essential and specialized functions. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

DHA and Its Elaborated Modulation of Antioxidant Defenses of the Brain: Implications in Aging and AD Neurodegeneration

DHA (docosahexaenoic acid) is perhaps the most pleiotropic molecule in nerve cell biology. This long-chain highly unsaturated fatty acid has evolved to accomplish essential functions ranging from structural components allowing fast events in nerve cell membrane physiology to regulation of neurogenesis and synaptic function. Strikingly, the plethora of DHA effects has to take place within the hostile pro-oxidant environment of the brain parenchyma, which might suggest a molecular suicide. In order to circumvent this paradox, different molecular strategies have evolved during the evolution of brain cells to preserve DHA and to minimize the deleterious effects of its oxidation. In this context, DHA has emerged as a member of the “indirect antioxidants” family, the redox effects of which are not due to direct redox interactions with reactive species, but to modulation of gene expression within thioredoxin and glutathione antioxidant systems and related pathways. Weakening or deregulation of these self-protecting defenses orchestrated by DHA is associated with normal aging but also, more worryingly, with the development of neurodegenerative diseases. In the present review, we elaborate on the essential functions of DHA in the brain, including its role as indirect antioxidant, the selenium connection for proper antioxidant function and their changes during normal aging and in Alzheimer’s disease.

Role of Citicoline in the Management of Traumatic Brain Injury

Head injury is among the most devastating types of injury, specifically called Traumatic Brain Injury (TBI). There is a need to diminish the morbidity related with TBI and to improve the outcome of patients suffering TBI. Among the improvements in the treatment of TBI, neuroprotection is one of the upcoming improvements. Citicoline has been used in the management of brain ischemia related disorders, such as TBI. Citicoline has biochemical, pharmacological, and pharmacokinetic characteristics that make it a potentially useful neuroprotective drug for the management of TBI. A short review of these characteristics is included in this paper. Moreover, a narrative review of almost all the published or communicated studies performed with this drug in the management of patients with head injury is included. Based on the results obtained in these clinical studies, it is possible to conclude that citicoline is able to accelerate the recovery of consciousness and to improve the outcome of this kind of patient, with an excellent safety profile. Thus, citicoline could have a potential role in the management of TBI.

Peritraumatic plasma Omega-3 fatty acid concentration predicts chronic pain severity following thermal burn injury

Chronic pain is a significant co-morbidity of burn injury affecting up to 60% of survivors. Currently, no treatments are available to prevent chronic pain after burn injury. Accumulating evidence suggests that omega-3 fatty acids (O3FA) improve symptoms across a range of painful conditions. In this study, we evaluated whether low peritraumatic levels of O3FA predicts greater pain severity during the year after burn injury. Burn survivors undergoing skin autograft were recruited from three participating burn centers. Plasma O3FA (n=77) levels were assessed in the early aftermath of burn injury using liquid chromatography/mass spectrometry and pain severity was assessed via the 0-10 numeric rating scale for 1 year following burn injury. Repeated-measures linear regression analyses were used to evaluate the association between peritraumatic O3FA concentrations and pain severity during the year following burn injury. Peritraumatic O3FA concentration and chronic pain severity were inversely related; lower levels of peritraumatic O3FA predicted worse pain outcomes (β=-.002, p=.020). Future studies are needed to evaluate biological mechanisms mediating this association and to assess the ability of O3FA to prevent chronic pain following burn injury.

Fatty Acids and Lipid Derivatives Protecting Photooxidative Attack in Age-related Macular Degeneration

The objective is the systematic review of studies published in Scielo, Redalyc, Dialnet, Web of Science, Scopus and Pubmed, related to the inclusion of fatty acids and lipid derivatives in the daily diet to prevent or delay the appearance or progression of Age-Related Macular Degeneration (AMD). The analysis of the research results consulted shows that AMD is one of the most frequent causes of blindness in subjects over 55 years of age. AMD is characterized by decreased vision, metamorphopsia, macropsies, micropsies, and central scotoma. Disease that must be diagnosed early as it can lead to irreversible blindness. Among the components of the diet that in numerous epidemiological studies have shown an association in the treatment of AMD and that are reviewed in this work are fatty acids, vitamins and carotenoids. There is ample evidence that fatty acids and lipid derivatives can be included in the diet plans of subjects with AMD.

Perinatal Dietary Polyunsaturated Fatty Acids in Brain Development, Role in Neurodevelopmental Disorders

n-3 and n-6 polyunsaturated fatty acids (PUFAs) are essential fatty acids that are provided by dietary intake. Growing evidence suggests that n-3 and n-6 PUFAs are paramount for brain functions. They constitute crucial elements of cellular membranes, especially in the brain. They are the precursors of several metabolites with different effects on inflammation and neuron outgrowth. Overall, long-chain PUFAs accumulate in the offspring brain during the embryonic and post-natal periods. In this review, we discuss how they accumulate in the developing brain, considering the maternal dietary supply, the polymorphisms of genes involved in their metabolism, and the differences linked to gender. We also report the mechanisms linking their bioavailability in the developing brain, their transfer from the mother to the embryo through the placenta, and their role in brain development. In addition, data on the potential role of altered bioavailability of long-chain n-3 PUFAs in the etiologies of neurodevelopmental diseases, such as autism, attention deficit and hyperactivity disorder, and schizophrenia, are reviewed.

Artificial intelligence and leukocyte epigenomics: Evaluation and prediction of late-onset Alzheimer's disease

We evaluated the utility of leucocyte epigenomic-biomarkers for Alzheimer’s Disease (AD) detection and elucidates its molecular pathogeneses. Genome-wide DNA methylation analysis was performed using the Infinium MethylationEPIC BeadChip array in 24 late-onset AD (LOAD) and 24 cognitively healthy subjects. Data were analyzed using six Artificial Intelligence (AI) methodologies including Deep Learning (DL) followed by Ingenuity Pathway Analysis (IPA) was used for AD prediction. We identified 152 significantly (FDR p<0.05) differentially methylated intragenic CpGs in 171 distinct genes in AD patients compared to controls. All AI platforms accurately predicted AD with AUCs ≥0.93 using 283,143 intragenic and 244,246 intergenic/extragenic CpGs. DL had an AUC = 0.99 using intragenic CpGs, with both sensitivity and specificity being 97%. High AD prediction was also achieved using intergenic/extragenic CpG sites (DL significance value being AUC = 0.99 with 97% sensitivity and specificity). Epigenetically altered genes included CR1L & CTSV (abnormal morphology of cerebral cortex), S1PR1 (CNS inflammation), and LTB4R (inflammatory response). These genes have been previously linked with AD and dementia. The differentially methylated genes CTSV & PRMT5 (ventricular hypertrophy and dilation) are linked to cardiovascular disease and of interest given the known association between impaired cerebral blood flow, cardiovascular disease, and AD. We report a novel, minimally invasive approach using peripheral blood leucocyte epigenomics, and AI analysis to detect AD and elucidate its pathogenesis.

New insights into targeting mitochondria in ischemic injury

Stroke is the leading cause of adult disability and death worldwide. Mitochondrial dysfunction has been recognized as a marker of neuronal death during ischemic stroke. Maintaining the function of mitochondria is important for improving the survival of neurons and maintaining neuronal function. Damaged mitochondria induce neuronal cell apoptosis by releasing reactive oxygen species (ROS) and pro-apoptotic factors. Mitochondrial fission and fusion processes and mitophagy are of great importance to mitochondrial quality control. This paper reviews the dynamic changes in mitochondria, the roles of mitochondria in different cell types, and related signaling pathways in ischemic stroke. This review describes in detail the role of mitochondria in the process of neuronal injury and protection in cerebral ischemia, and integrates neuroprotective drugs targeting mitochondria in recent years, which may provide a theoretical basis for the progress of treatment of ischemic stroke. The potential of mitochondrial-targeted therapy is also emphasized, which provides valuable insights for clinical research.