Resolvins, docosatrienes, and neuroprotectins, novel omega-3-derived mediators, and their endogenous aspirin-triggered epimers

Resolvins D5 and D1 undergo phase II metabolism by uridine 5'-diphospho-glucuronosyltransferases

Specialized pro-resolving mediators (SPMs) are oxidized lipid mediators that have been shown to resolve inflammation in cellular and animal models as well as humans. SPMs and their biological precursors are even commercially available as dietary supplements. It has been understood for more than forty years that pro-inflammatory oxidized lipid mediators, including prostaglandins and leukotrienes, are rapidly inactivated via metabolism. Studies on the metabolism of SPMs are, however, limited. Herein, we report that resolvin D5 (RvD5) and resolvin D1 (RvD1), well-studied SPMs, are readily metabolized by human liver microsomes (HLM) to glucuronide conjugated metabolites. We further show that this transformation is catalyzed by specific uridine 5'-diphospho-glucuronosyltransferase (UGT) isoforms. Additionally, we demonstrate that RvD5 and RvD1 metabolism by HLM is influenced by non-steroidal anti-inflammatory drugs (NSAIDs), which can act as UGT inhibitors through cyclooxygenase-independent mechanisms. The results from these studies highlight the importance of considering metabolism, as well as factors that influence metabolic enzymes, when seeking to quantify SPMs in vivo.

Protective Effects of 7S,15R-Dihydroxy-16S,17S-Epoxy-Docosapentaenoic Acid (diHEP-DPA) against Blue Light-Induced Retinal Damages in A2E-Laden ARPE-19 Cells

The purpose of this study was to investigate the protective effects of 7S,15R-dihydroxy-16S,17S-epoxy-docosapentaenoic acid (diHEP-DPA) in retinal pigment epithelial (RPE) cell damage. ARPE-19 cells, a human RPE cell line, were cultured with diHEP-DPA and Bis-retinoid N-retinyl-N-retinylidene ethanolamine (A2E), followed by exposure to BL. Cell viability and cell death rates were determined. Western blotting was performed to determine changes in apoptotic factors, mitogen-activated protein kinase (MAPK) family proteins, inflammatory proteins, and oxidative and carbonyl stresses. The levels of pro-inflammatory cytokines in the culture medium supernatants were also measured. Exposure to A2E and BL increased the ARPE-19 cell death rate, which was alleviated by diHEP-DPA in a concentration-dependent manner. A2E and BL treatments induced apoptosis in ARPE-19 cells, which was also alleviated by diHEP-DPA. Analysis of the relationship with MAPK proteins revealed that the expression of p-JNK and p-P38 increased after A2E and BL treatments and decreased with exposure to diHEP-DPA in a concentration-dependent manner. DiHEP-DPA also affected the inflammatory response by suppressing the expression of inflammatory proteins and the production of pro-inflammatory cytokines. Furthermore, it was shown that diHEP-DPA regulated the proteins related to oxidative and carbonyl stresses. Taken together, our results provide evidence that diHEP-DPA can inhibit cell damage caused by A2E and BL exposure at the cellular level by controlling various pathways involved in apoptosis and inflammatory responses.

A Narrative Review of the Published Pre-Clinical Evaluations: Multiple Effects of Arachidonic Acid, its Metabolic Enzymes and Metabolites in Epilepsy

Arachidonic acid (AA), an important polyunsaturated fatty acid in the brain, is hydrolyzed by a direct action of phospholipase A2 (PLA2) or through the combined action of phospholipase C and diacylglycerol lipase, and released into the cytoplasm. Various derivatives of AA can be synthesized mainly through the cyclooxygenase (COX), lipoxygenase (LOX) and cytochrome P450 (P450) enzyme pathways. AA and its metabolic enzymes and metabolites play important roles in a variety of neurophysiological activities. The abnormal metabolites and their catalytic enzymes in the AA cascade are related to the pathogenesis of various central nervous system (CNS) diseases, including epilepsy. Here, we systematically reviewed literatures in PubMed about the latest randomized controlled trials, animal studies and clinical studies concerning the known features of AA, its metabolic enzymes and metabolites, and their roles in epilepsy. The exclusion criteria include non-original studies and articles not in English.

Fatty acids and their metabolites (resolvins) are altered in women with gestational diabetes mellitus (GDM)

The maternal fatty acid status plays a key role in influencing pregnancy outcomes. Omega-3 fatty acids are the precursors for E-series (RvE) and D-series resolvins (RvD) and possess anti-inflammatory properties. Pregnancy complications like gestational diabetes mellitus (GDM) are associated with excess maternal inflammation. This study reports the levels of maternal fatty acids across gestation in GDM and non-GDM women, placental fatty acids, resolvins and their association with the maternal fatty acid status. Pregnant women were recruited at 11-14 (V1) weeks and followed at 18-22 (V2) and 26-28 (V3) weeks and at delivery (V4). A total of 209 women who were diagnosed as GDM and 207 non-GDM women were included in this study. Fatty acids were estimated using gas chromatography. The protein levels of resolvins (RvE1, RvE2, RvD1 and RvD2) were measured using ELISA kits. Total PUFAs, eicosapentaenoic acid (EPA), omega-6 fatty acids, linoleic acid (LA) and arachidonic acid (AA) were lower, while saturated fatty acid (SFA) and alpha-linolenic acid (ALA) levels were higher in GDM women at 18-22 weeks. Placental AA was lower (p < 0.05) in women with GDM. Placental protein levels of RvE1, RvD1 and RvD2 were lower (p < 0.001 for all) in the GDM group. The maternal delta 5 desaturase index was positively associated, while erythrocyte omega-3 and omega-6 fatty acids were negatively associated with RvE2 at 11-14 weeks. Placental LA and ALA were positively associated with RvD1 and RvD2 (p < 0.05, for both), respectively. Our findings suggest that the maternal fatty acid status influences pro-resolving mediators which may lead to increased inflammation in GDM.

Interface between Resolvins and Efferocytosis in Health and Disease

Acute inflammation resolution acts as a vital process for active host response, tissue support, and homeostasis maintenance, during which resolvin D (RvD) and E (RvE) as mediators derived from omega-3 polyunsaturated fatty acids display specific and stereoselective anti-inflammations like restricting neutrophil infiltration and pro-resolving activities. On the other side of the coin, potent macrophage-mediated apoptotic cell clearance, namely efferocytosis, is essential for successful inflammation resolution. Further studies mentioned a linkage between efferocytosis and resolvins. For instance, resolvin D1 (RvD1), which is endogenously formed from docosahexaenoic acid within the inflammation resolution, thereby provoking efferocytosis. There is still limited information regarding the mechanism of action of RvD1-related efferocytosis enhancement at the molecular level. The current review article was conducted to explore recent data on how the efferocytosis process and resolvins relate to each other during the inflammation resolution in illness and health. Understanding different aspects of this connection sheds light on new curative approaches for medical conditions caused by defective efferocytosis and disrupted inflammation resolution.

Lipid-Mediated Mechanisms of Thermal Adaptation and Thermoregulatory Behavior in Animals

Temperature affects a variety of cellular processes because the molecular motion of cellular constituents and the rate of biochemical reactions are sensitive to temperature changes. Thus, the adaptation to temperature is necessary to maintain cellular functions during temperature fluctuation, particularly in poikilothermic organisms. For a wide range of organisms, cellular lipid molecules play a pivotal role during thermal adaptation. Temperature changes affect the physicochemical properties of lipid molecules, resulting in the alteration of cell membrane-related functions and energy metabolism. Since the chemical structures of lipid molecules determine their physicochemical properties and cellular functions, cellular lipids, particularly fatty acid-containing lipid molecules, are remodeled as a thermal adaptation response to compensate for the effects of temperature change. In this chapter, we first introduce the structure and biosynthetic pathway of fatty acid-containing lipid molecules, such as phospholipid and triacylglycerol, followed by a description of the cellular lipid-mediated mechanisms of thermal adaptation and thermoregulatory behavior in animals.

The effect of SARS-CoV-2 variants on the plasma oxylipins and PUFAs of COVID-19 patients

Oxylipins are important signalling compounds that are significantly involved in the regulation of the immune system and the resolution of inflammation. Lipid metabolism is strongly activated upon SARS-CoV-2 infection, however the modulating effects of oxylipins induced by different variants remain unexplored. Here, we compare the plasma profiles of thirty-seven oxylipins and four PUFAs in subjects infected with Wild-type, Alpha (B.1.1.7), Delta (B.1.617.2), and Omicron (B.1.1.529) variants. The results suggest that oxidative stress and inflammation resulting from COVID-19 were highly dependent on the SARS-CoV-2 variant, and that the Wild-type elicited the strongest inflammatory storm. The Alpha and Delta variants induced a comparable lipid profile alteration upon infection, which differed significantly from Omicron. The latter variant increased the levels of pro-inflammatory mediators and decreased the levels of omega-3 PUFA in infected patients. We speculate that changes in therapeutics, vaccination, and prior infections may have a role in the alteration of the oxylipin profile besides viral mutations. The results shed new light on the evolution of the inflammatory response in COVID-19.

Differential effects of resolvin D1 and resolvin E1 on cementoblast function

BACKGROUND

Resolvins are endogenous mediators of the resolution of inflammation. They are derived from omega-3 polyunsaturated fatty acid precursors. Resolvin D1 (RvD1) and Resolvin E1 (RvE1) are the best-characterized members for actively promoting periodontal regeneration in experimental animal models. Here, we evaluated the efficacy of RvD1 and RvE1 on cementoblasts, the key cells involved in dental cementum regeneration and the attachment of the tooth to the alveolar bone.

METHODS

Immortalized mouse cementoblasts (OCCM-30) were treated with different concentrations (0.1-1000 ng/mL) of RvD1 and RvE1. Cell proliferation was measured using an electrical impedance-based real-time cell analyzer. Mineralization was evaluated with von Kossa staining. The mRNA expression of mineralized tissue-associated markers of bone sialoprotein (BSP), Type I collagen (COL I), osteocalcin (OCN), osteopontin (OPN), runt-related transcription factor 2 (RunX2), alkaline phosphatase (ALP), osteoprotegerin (OPG), receptor activator of nuclear factor kappa B (NF-κB) (RANK), receptor activator of NF-κB ligand (RANKL), and extracellular matrix-degrading enzymes [matrix metalloproteinase (MMP)-1, MMP-2, MMP-3, MMP-9, and their tissue inhibitors (TIMP-1, TIMP-2)], RvE1 receptor (ChemR23) and RvD1 receptor (ALX/PFR2), cytokines (tumor necrosis factor-alpha {TNF-α}, interleukin {IL}-1β, IL-6, IL-8, IL-10, IL-17), oxidative stress enzymes [superoxide dismutase (SOD), glutathione peroxidase (GPX), and cyclooxygenase-2 (Cox-2)] were analyzed using quantitative polymerase chain reaction (qPCR).

RESULTS

Both RvD1 and RvE1 (10-100 ng/mL) significantly increased the proliferation of cementoblasts and mineralized nodules at all concentrations (p < 0.05). RvE1 increased BSP, RunX2, and ALP compared with the RvD1 dose and time-dependently, while RvD1 and RvE1 differentially regulated COL-I. RvE1 increased OPG mRNA expression, whereas RANK-RANKL mRNA expression decreased by RvE1. MMP-2, MMP-3, MMP-9, TIMP-1, and TIMP-2 expressions were reduced by RvE1 compared with RvD1. Treatment of cementoblasts with RvD1 and RvE1 differentially affected cytokine and oxidative stress enzymes while significantly increasing their receptor expressions (ChemR23 and ALX/PFR2).

CONCLUSIONS

RvD1 and RvE1 regulate proliferation, mineralization, and gene expression in cementoblasts using similar pathways while differentially affecting tissue degradation, suggesting a targeted therapeutic approach for cementum turnover during periodontal regeneration.

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.

Immunomodulation of periodontitis with SPMs

Inflammation is a critical component in the pathophysiology of numerous disease processes, with most therapeutic modalities focusing on its inhibition in order to achieve treatment outcomes. The resolution of inflammation is a separate, distinct pathway that entails the reversal of the inflammatory process to a state of homoeostasis rather than selective inhibition of specific components of the inflammatory cascade. The discovery of specialized pro-resolving mediators (SPMs) resulted in a paradigm shift in our understanding of disease etiopathology. Periodontal disease, traditionally considered as one of microbial etiology, is now understood to be an inflammation-driven process associated with dysbiosis of the oral microbiome that may be modulated with SPMs to achieve therapeutic benefit.

Inflammation resolution and specialized pro-resolving lipid mediators in chronic rhinosinusitis

INTRODUCTION

In chronic rhinosinusitis (CRS), a complex pathophysiology results from varied pro-inflammatory stimuli but is consistently characterized by classic cellular, molecular, and microbial alterations. Normally, endogenous specialized pro-resolving mediators (SPM) actively promote resolution of inflammation through numerous pathways, including those involved in host antimicrobial defense. However, these pathways appear to be disrupted in CRS.

AREAS COVERED

This paper describes features of CRS in the context of chronic tissue inflammation, and potential mechanisms by which specialized pro-resolving mediators promote active resolution of tissue inflammation.

EXPERT OPINION

Temporal phases of resolution must be tightly regulated to successfully resolve inflammation in CRS while preserving tissue functions such as barrier maintenance and special sensory function. Dysregulation of SPM enzymatic pathways has been recently shown in CRS and is associated with disease phenotypes and microbial colonization patterns. Current research in animal models and in vitro human cell culture, as well as human dietary studies, demonstrate relevant changes in cell signaling with lipid mediator bioavailability. Further clinical research may provide insight into the therapeutic value of this approach in CRS.

Resolution of inflammation in oral diseases

The resolution of inflammation is an essential endogenous process that protects host tissues from an exaggerated chronic inflammatory response. Multiple interactions between host cells and resident oral microbiome regulate the protective functions that lead to inflammation in the oral cavity. Failure of appropriate regulation of inflammation can lead to chronic inflammatory diseases that result from an imbalance between pro-inflammatory and pro-resolution mediators. Thus, failure of the host to resolve inflammation can be considered an essential pathological mechanism for progression from the late stages of acute inflammation to a chronic inflammatory response. Specialized pro-resolving mediators (SPMs), which are essential polyunsaturated fatty acid (PUFA)-derived autacoid mediators, aid in regulating the endogenous inflammation resolving process by stimulating immune cell-mediated clearance of apoptotic polymorphonuclear neutrophils, cellular debris, and microbes, restricting further neutrophil tissue infiltration, and counter-regulating pro-inflammatory cytokine production. The SPM superfamily contains four specialized lipid mediator families: lipoxins, resolvins, protectins, and maresins that can activate resolution pathways. Understanding the crosstalk between resolution signals in the tissue response to injury has therapeutic application potential for preventing, maintaining, and regenerating chronically damaged tissues. Here, we discuss the fundamental concepts of resolution as an active biochemical process, novel concepts demonstrating the role of resolution mediators in tissue regeneration in periodontal and pulpal diseases, and future directions for therapeutic applications with particular emphasis on periodontal therapy.

Major structure-activity relationships of resolvins, protectins, maresins and their analogues

Resolvins, protectins and maresins are a series of polyunsaturated fatty acid-derived molecules which play important roles in the resolution of inflammation. They are termed specialized proresolving mediators and facilitate a return to homeostasis following an inflammatory response. These molecules are currently the focus of intensive investigation, primarily for their ability to suppress inflammation in chronic disease states. Researchers have employed different synthetic approaches to assess whether various structural modifications of these compounds could provide access to future therapeutics. This review summarizes the modifications made thus far and focuses on the key structure-activity relationships which have been uncovered for resolvins, protectins, maresins and their analogues.

Exposing intracellular molecular changes during the differentiation of human-induced pluripotent stem cells into erythropoietin-producing cells using Raman spectroscopy and imaging

The objective of this study was to explore intracellular molecular changes during the differentiation of human-induced pluripotent stem cells (iPSCs) into erythropoietin (EPO)-producing cells using Raman spectroscopy and imaging. Raman imaging data of fixed cells at four stages of cell differentiation were analyzed by a partial least squares (PLS) regression model, and the variations in the intracellular molecular compositions with cell differentiation were investigated. As a result, three biomarkers characterizing the cell phases were identified: dimethyl sulfoxide (DMSO), fatty acids with a low grade of unsaturation, and glycoproteins. The uptake of DMSO by EPO-producing cells, which was added into a culture medium as an inducer for cell differentiation, was detected, and the increase in unsaturated fatty acid concentrations was revealed that lipid metabolism changed over the course of cell differentiation. The decrease in the glycoprotein concentration after the cell phase during which iPSCs differentiated into EPO-producing cells was also made clear. Raman imaging successfully visualized chemical images of these three biomarkers in two dimensions, where the biomarker concentrations independently varied during cell differentiation. These results demonstrated the application potential of the proposed method to regenerative medicine for monitoring cell differentiation and discriminating cell maturation in situ at the molecular level.

Anti-Inflammatory and Antioxidant Properties of Malapterurus electricus Skin Fish Methanolic Extract in Arthritic Rats: Therapeutic and Protective Effects

The protective and therapeutic anti-inflammatory and antioxidant potency of Malapterurus electricus (F. Malapteruridae) skin fish methanolic extract (FE) (300 mg/kg.b.wt/day for 7 days, orally) was tested in monosodium urate(MSU)-induced arthritic Wistar albino male rats' joints. Serum uric acid, TNF-α, IL-1β, NF-𝜅B, MDA, GSH, catalase, SOD, and glutathione reductase levels were all measured. According to the findings, FE significantly reduced uric acid levels and ankle swelling in both protective and therapeutic groups. Furthermore, it has anti-inflammatory effects by downregulating inflammatory cytokines, primarily through decreased oxidative stress and increased antioxidant status. All the aforementioned lesions were significantly improved in protected and treated rats with FE, according to histopathological findings. iNOS immunostaining revealed that protected and treated arthritic rats with FE had weak positive immune-reactive cells. Phytochemical analysis revealed that FE was high in fatty and amino acids. The most abundant compounds were vaccenic (24.52%), 9-octadecenoic (11.66%), palmitic (34.66%), stearic acids (14.63%), glycine (0.813 mg/100 mg), and alanine (1.645 mg/100 mg). Extensive molecular modelling and dynamics simulation experiments revealed that compound 4 has the potential to target and inhibit COX isoforms with a higher affinity for COX-2. As a result, we contend that FE could be a promising protective and therapeutic option for arthritis, aiding in the prevention and progression of this chronic inflammatory disease.

Resolvin E1 Reduces Tumor Growth in a Xenograft Model of Lung Cancer

Inflammation plays a significant role in carcinogenesis and tumor growth. The current study was designed to test the hypothesis that resolvin E1 (RvE1) and overexpression of the receptor for RvE1 (ERV1) will prevent and/or reverse tumor generation in a gain-of-function mouse model of tumor seeding with lung cancer cells. To measure the impact of enhanced resolution of inflammation on cancer pathogenesis, ERV1-overexpressing transgenic (TG) and wild-type FVB mice were given an injection of 1 × 106 LA-P0297 cells subcutaneously and were treated with RvE1 (100 ng; intraperitoneally) or placebo. To assess the impact of RvE1 as an adjunct to chemotherapy, ERV1-TG and wild-type FVB mice were treated with cisplatin or cisplatin + RvE1. RvE1 significantly prevented tumor growth and reduced tumor size, cyclooxygenase-2, NF-κB, and proinflammatory cytokines in TG animals as compared to wild-type animals. A significant decrease in Ki-67, vascular endothelial growth factor, angiopoietin (Ang)-1, and Ang-2 was also observed in TG animals as compared to wild-type animals. Tumor-associated neutrophils and macrophages were significantly reduced by RvE1 in transgenics (P < 0.001). RvE1 administration with cisplatin led to a significant reduction of tumor volume and reduced cyclooxygenase-2, NF-κB, vascular endothelial growth factor-A, Ang-1, and Ang-2. These data suggest that RvE1 prevents inflammation and vascularization, reduces tumor seeding and tumor size, and, when used as an adjunct to chemotherapy, enhances tumor reduction at significantly lower doses of cisplatin.

Inflammation as a link between periodontal disease and obesity

Nutrition plays a critical role in the homeostatic balance, maintenance of health, and longevity. There is a close link between inflammatory diseases and nutritional health. Obesity is a severe pathological process with grave implications on several organ systems and disease processes, including type 2 diabetes, cardiovascular disease, osteoarthritis, and rheumatoid arthritis. The impact of obesity on periodontal inflammation has not been fully understood; the association between nutritional balance and periodontal inflammation is much less explored. This review is focused on the potential mechanistic links between periodontal diseases and obesity and common inflammatory activity pathways that can be pharmacologically targeted.

Long COVID and long chain fatty acids (LCFAs): Psychoneuroimmunity implication of omega-3 LCFAs in delayed consequences of COVID-19

The global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the lasting pandemic of coronavirus disease 2019 (COVID-19) and the post-acute phase sequelae of heterogeneous negative impacts in multiple systems known as the "long COVID." The mechanisms of neuropsychiatric complications of long COVID are multifactorial, including long-term tissue damages from direct CNS viral involvement, unresolved systemic inflammation and oxidative stress, maladaptation of the renin-angiotensin-aldosterone system and coagulation system, dysregulated immunity, the dysfunction of neurotransmitters and hypothalamus-pituitaryadrenal (HPA) axis, and the psychosocial stress imposed by societal changes in response to this pandemic. The strength of safety, well-acceptance, and accumulating scientific evidence has now afforded nutritional medicine a place in the mainstream of neuropsychiatric intervention and prophylaxis. Long chain omega-3 polyunsaturated fatty acids (omega-3 or n-3 PUFAs) might have favorable effects on immunity, inflammation, oxidative stress and psychoneuroimmunity at different stages of SARS-CoV-2 infection. Omega-3 PUFAs, particularly EPA, have shown effects in treating mood and neurocognitive disorders by reducing pro-inflammatory cytokines, altering the HPA axis, and modulating neurotransmission via lipid rafts. In addition, omega-3 PUFAs and their metabolites, including specialized pro-resolvin mediators, accelerate the process of cleansing chronic inflammation and restoring tissue homeostasis, and therefore offer a promising strategy for Long COVID. In this article, we explore in a systematic review the putative molecular mechanisms by which omega-3 PUFAs and their metabolites counteract the negative effects of long COVID on the brain, behavior, and immunity.

Biochemical and Metabolical Pathways Associated with Microbiota-Derived Butyrate in Colorectal Cancer and Omega-3 Fatty Acids Implications: A Narrative Review

Knowledge regarding the influence of the microbial community in cancer promotion or protection has expanded even more through the study of bacterial metabolic products and how they can modulate cancer risk, which represents an extremely challenging approach for the relationship between intestinal microbiota and colorectal cancer (CRC). This review discusses research progress on the effect of bacterial dysbiosis from a metabolic point of view, particularly on the biochemical mechanisms of butyrate, one of the main short chain fatty acids (SCFAs) with anti-inflammatory and anti-tumor properties in CRC. Increased daily intake of omega-3 polyunsaturated fatty acids (PUFAs) significantly increases the density of bacteria that are known to produce butyrate. Omega-3 PUFAs have been proposed as a treatment to prevent gut microbiota dysregulation and lower the risk or progression of CRC.

Role of Specialized Pro-Resolving Mediators in Modifying Host Defense and Decreasing Bacterial Virulence

Bacterial infection activates the innate immune system as part of the host’s defense against invading pathogens. Host response to bacterial pathogens includes leukocyte activation, inflammatory mediator release, phagocytosis, and killing of bacteria. An appropriate host response requires resolution. The resolution phase involves attenuation of neutrophil migration, neutrophil apoptosis, macrophage recruitment, increased phagocytosis, efferocytosis of apoptotic neutrophils, and tissue repair. Specialized Pro-resolving Mediators (SPMs) are bioactive fatty acids that were shown to be highly effective in promoting resolution of infectious inflammation and survival in several models of infection. In this review, we provide insight into the role of SPMs in active host defense mechanisms for bacterial clearance including a new mechanism of action in which an SPM acts directly to reduce bacterial virulence.

Aspirin-triggered resolvin D1 reduces parasitic cardiac load by decreasing inflammation in a murine model of early chronic Chagas disease

Background

Chagas disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America and is widely distributed worldwide because of migration. In 30% of cases, after years of infection and in the absence of treatment, the disease progresses from an acute asymptomatic phase to a chronic inflammatory cardiomyopathy, leading to heart failure and death. An inadequate balance in the inflammatory response is involved in the progression of chronic Chagas cardiomyopathy. Current therapeutic strategies cannot prevent or reverse the heart damage caused by the parasite. Aspirin-triggered resolvin D1 (AT-RvD1) is a pro-resolving mediator of inflammation that acts through N-formyl peptide receptor 2 (FPR2). AT-RvD1 participates in the modification of cytokine production, inhibition of leukocyte recruitment and efferocytosis, macrophage switching to a nonphlogistic phenotype, and the promotion of healing, thus restoring organ function. In the present study, AT-RvD1 is proposed as a potential therapeutic agent to regulate the pro-inflammatory state during the early chronic phase of Chagas disease.

Methodology/Principal findings

C57BL/6 wild-type and FPR2 knock-out mice chronically infected with T. cruzi were treated for 20 days with 5 μg/kg/day AT-RvD1, 30 mg/kg/day benznidazole, or the combination of 5 μg/kg/day AT-RvD1 and 5 mg/kg/day benznidazole. At the end of treatment, changes in immune response, cardiac tissue damage, and parasite load were evaluated. The administration of AT-RvD1 in the early chronic phase of T. cruzi infection regulated the inflammatory response both at the systemic level and in the cardiac tissue, and it reduced cellular infiltrates, cardiomyocyte hypertrophy, fibrosis, and the parasite load in the heart tissue.

Conclusions/Significance

AT-RvD1 was shown to be an attractive therapeutic due to its regulatory effect on the inflammatory response at the cardiac level and its ability to reduce the parasite load during early chronic T. cruzi infection, thereby preventing the chronic cardiac damage induced by the parasite.

Chagas disease is prevalent in Latin America and is widely distributed worldwide due to migration. In 30% of patients, if the parasite is left untreated, the disease may progress from an acute symptomless phase to chronic myocardial inflammation, which can cause heart failure and death, years after the infection. Imbalances in the inflammatory response are related to this progression. Current treatments cannot prevent or reverse the cardiac damage inflicted by the parasite. Aspirin-triggered resolvin D1, also named AT-RvD1, can modify cellular and humoral inflammatory responses leading to the resolution of inflammation, thus promoting healing and restoring organ function. In this study, AT-RvD1, in an N-formyl peptide receptor 2 (FPR2)-dependent manner, was shown to regulate local and systemic inflammation and decrease cellular infiltration in the heart tissue of mice chronically infected with the parasite and reduce cardiac hypertrophy and fibrosis in the early stages of the chronic phase of the disease. Importantly, AT-RvD1 was able to decrease parasite load in the infected hearts. Thus, this research indicates that At-RvD1 treatment is a potential therapeutic strategy that offers an improvement on current drug therapies.

RvD1 treatment during primary infection modulates memory response increasing viral load during respiratory viral reinfection

Resolvin D1 (RvD1), which is biosynthesized from essential long-chain fatty acids, is involved in anti-inflammatory activity and modulation of T cell response. Memory CD8+ T cells are important for controlling tumor growth and viral infections. Exacerbated inflammation has been described as impairing memory CD8+ T cell differentiation. This study aimed to verify the effects of RvD1 on memory CD8+ T cells in vitro and in vivo in a respiratory virus infection model. Peripheral blood mononuclear cells were treated at different time points with RvD1 and stimulated with anti-CD3/anti-CD28 antibodies. Pre-treatment with RvD1 increases the expansion of memory CD8+ T cells. The IL-12 level, a cytokine described to control memory CD8+ T cells, was reduced with RvD1 pre-treatment. When the mTOR axis was inhibited, the IL-12 levels were restored. In a respiratory virus infection model, Balb/c mice were treated with RvD1 before infection or after 7 days after infection. RvD1 treatment after infection increased the frequency of memory CD8+ T cells in the lung expressing II4, II10, and Ifng. During reinfection, RvD1-treated and RSV-infected mice present a high viral load in the lung and lower antibody response in the serum. Our results show that RvD1 modulates the expansion and phenotype of memory CD8+ T cells but contributed to a non-protective response after RSV reinfection.

Specialized pro-resolving mediators: biosynthesis and biological role in bacterial infections

Acute inflammation caused by bacterial infections is an essential biological defence mechanism of the host in order to neutralize and clear the invaders and to return to homeostasis. Despite its protective function, inflammation may become persistent and uncontrolled, resulting in chronic diseases and tissue destruction as consequence of the unresolved inflammatory process. Therefore, spatiotemporal induction of endogenous inflammation resolution programs that govern bacterial clearance as well as tissue repair and regeneration, are of major importance in order to enable tissues to restore functions. Lipid mediators that are de-novo biosynthesized from polyunsaturated fatty acids (PUFAs) mainly by lipoxygenases and cyclooxygenases, critically regulate the initiation, the maintenance but also the resolution of infectious inflammation and tissue regeneration. The discovery of specialized pro-resolving mediators (SPMs) generated from omega-3 PUFAs stimulated intensive research in inflammation resolution, especially in infectious inflammation elicited by bacteria. SPMs are immunoresolvents that actively terminate inflammation by limiting neutrophil influx, stimulating phagocytosis, bacterial killing and clearance as well as efferocytosis of apoptotic neutrophils and cellular debris by macrophages. Moreover, SPMs prevent collateral tissue damage, promote tissue repair and regeneration and lower antibiotic requirement. Here, we review the biosynthesis of SPMs in bacterial infections and cover specific mechanisms of SPMs that govern the resolution of bacteria-initiated inflammation.

Neuroaspis PLP10™, a nutritional formula rich in omega-3 and omega-6 fatty acids with antioxidant vitamins including gamma-tocopherol in early Parkinson's disease: A randomized, double-blind, placebo-controlled trial

In the present study, we investigated whether Neuroaspis PLP10™, a well-designed intervention, rich in omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFAs) with specific antioxidant vitamins, may exert positive action in the improvement of Parkinson's disease symptoms and perhaps delay the progression of the disease when used as an adjuvant to the conventional treatment. Forty patients were randomized 1:1 to receive either 20 ml dose, once daily, of control (pure virgin olive oil) or Neuroaspis PLP 10™, a formula containing a mixture of omega-3 (810 mg Eicosapentaenoic acid and 4140 mg Docosahexaenoic acid) and omega-6 fatty acids (1800 mg gamma-Linolenic acid and 3150 mg Linoleic acid) (1:1 w/w), with 0.6 mg vitamin A, vitamin E (22 mg) plus pure gamma (γ)-tocopherol (760 mg), for a total of 30 months in a randomized double-blind, placebo-controlled trial. Participants completed assessments based on the Hoehn and Yahr Staging Scale of Parkinson's Disease (HY scale) and the Unified Parkinson's Disease Rating Scale (UPDRS) III. Overall, for this small sample size clinical trial, Neuroaspis PLP10™ supplementation as an adjuvant treatment for 30 months in PD patients significantly delayed disease progression according to UPDRS (p ≤ 0.05) Vs placebo.

Prostaglandin E2, 9S-, 13S-HODE and resolvin D1 are strongly associated with the post-stroke cognitive impairment

BACKGROUND

Inflammatory derivatives of free fatty acids are involved in the development of neuroinflammation and cognitive dysfunctions. The study aim was to establish the influence of eicosanoids on the cognitive status of stroke patients.

METHODS

73 stroke patients were prospectively evaluated towards the neuropsychological cognitive functions on the 7th day after stroke and after follow-up of 6 months. Eicosanoids levels were measured in all patients and compared to stroke-free controls (n = 30).

RESULTS

Prostaglandin E2 was negatively correlated with Montreal Cognitive Assessment (MOCA) test on the 7th day after stroke. The level of 9-hydroxyoctadecadienoic acid (9S-HODE) was significantly higher in patients with cognitive dysfunctions in MOCA test compared to the others (group I mean ± SD: 0.040 ± 0.035 vs. group II: 0.0271 ± 0.016). In the initial neuropsychological assessment maresin 1-, 5-hydroxyeicosatetraenoic acid (HETE), 12S-HETE and 15S-HETE were negatively correlated with California Verbal Learning Test (CVLT) and thus with cognitive functions, while in the follow-up examination negative correlations were identified for prostaglandin E2, meresin 1, leukotriene B4, 13S HODE, 9S-HODE; the only positive correlation was observed in 15S-HETE. Other neuropsychological tests showed a beneficial impact of resolvin D1 and a negative role of prostaglandin E2 was observed in the first examination and in the follow-up. Resolvin D1 and the group of all analyzed eicosanoids predict changes in cognitive functions.

CONCLUSIONS

Eicosanoids can play a role in the neuroinflammation. They can affect the cognitive status at the stroke onset and have a predictive value for post-stroke cognitive decline. Prostaglandin E2, 9S-, 13S-HODE and resolvin D1 are the most important inflammatory free fatty acid derivatives in the cognitive functions in stroke. Eicosanoids predict post-stroke cognitive functions.

N-3 Polyunsaturated Fatty Acids and Their Lipid Mediators as A Potential Immune-Nutritional Intervention: A Molecular and Clinical View in Hepatic Disease and Other Non-Communicable Illnesses

In recent years, the beneficial effect of n-3 polyunsaturated fatty acids (n-3 PUFAs) intake on human health has been widely accepted in the field of immunonutrition. Today, we find a diversity of supplements based on n-3 PUFAs and/or minerals, vitamins and other substances. The main objective of this review is to discuss the importance of n-3 PUFAs and their derivatives on immunity and inflammatory status related to liver disease and other non-communicable illnesses. Based on the burden of liver diseases in 2019, more than two million people die from liver pathologies per year worldwide, because it is the organ most exposed to agents such as viruses, toxins and medications. Consequently, research conducted on n-3 PUFAs for liver disease has been gaining prominence with encouraging results, given that these fatty acids have anti-inflammatory and cytoprotective effects. In addition, it has been described that n-3 PUFAs are converted into a novel species of lipid intermediaries, specialized pro-resolving mediators (SPMs). At specific levels, SPMs improve the termination of inflammation as well as the repairing and regeneration of tissues, but they are deregulated in liver disease. Since evidence is still insufficient to carry out pharmacological trials to benefit the resolution of acute inflammation in non-communicable diseases, there remains a call for continuing preclinical and clinical research to better understand SPM actions and outcomes.

Inflammation and tumor progression: signaling pathways and targeted intervention

Cancer development and its response to therapy are regulated by inflammation, which either promotes or suppresses tumor progression, potentially displaying opposing effects on therapeutic outcomes. Chronic inflammation facilitates tumor progression and treatment resistance, whereas induction of acute inflammatory reactions often stimulates the maturation of dendritic cells (DCs) and antigen presentation, leading to anti-tumor immune responses. In addition, multiple signaling pathways, such as nuclear factor kappa B (NF-kB), Janus kinase/signal transducers and activators of transcription (JAK-STAT), toll-like receptor (TLR) pathways, cGAS/STING, and mitogen-activated protein kinase (MAPK); inflammatory factors, including cytokines (e.g., interleukin (IL), interferon (IFN), and tumor necrosis factor (TNF)-α), chemokines (e.g., C-C motif chemokine ligands (CCLs) and C-X-C motif chemokine ligands (CXCLs)), growth factors (e.g., vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β), and inflammasome; as well as inflammatory metabolites including prostaglandins, leukotrienes, thromboxane, and specialized proresolving mediators (SPM), have been identified as pivotal regulators of the initiation and resolution of inflammation. Nowadays, local irradiation, recombinant cytokines, neutralizing antibodies, small-molecule inhibitors, DC vaccines, oncolytic viruses, TLR agonists, and SPM have been developed to specifically modulate inflammation in cancer therapy, with some of these factors already undergoing clinical trials. Herein, we discuss the initiation and resolution of inflammation, the crosstalk between tumor development and inflammatory processes. We also highlight potential targets for harnessing inflammation in the treatment of cancer.

Free Fatty Acids Are Associated with the Cognitive Functions in Stroke Survivors

Ischemic stroke is a leading cause of motor impairment and psychosocial disability. Although free fatty acids (FFA) have been proven to affect the risk of stroke and potentially dementia, the evidence of their impact on cognitive functions in stroke patients is lacking. We aimed to establish such potential relationships. Seventy-two ischemic stroke patients were prospectively analysed. Their cognitive functions were assessed seven days post-stroke and six months later as follow-up (n = 41). Seven days post-stroke analysis of serum FFAs levels showed direct correlations between Cognitive Verbal Learning Test (CVLT) and the following FFAs: C20:4n6 arachidonic acid and C20:5n3 eicosapentaenoic acid, while negative correlations were observed for C18:3n3 linolenic acid (ALA), C18:4 n3 stearidonic acid and C23:0 tricosanoic acid. Follow-up examination with CVLT revealed positive correlations with C15:0 pentadecanoid acid, C18:3n6 gamma linoleic acid, SDA, C23:0 tricosanoic acid and negative correlations with C14:0 myristic acid and C14:1 myristolenic acids. Several tests (Trail Making Test, Stroop Dots Trail, Digit Span Test and Verbal Fluency Test) were directly correlated mainly with C14:0 myristic acid and C14:1 myristolenic acid, while corresponding negatively with C18:1 vaccinic acid, C20:3n3 cis-11-eicosatrienoic acid, C22:1/C20:1 cis11- eicosanic acid and C20:2 cis-11-eicodienoic acid. No correlations between Montreal Cognitive Assessment (MOCA) test performed on seventh day, and FFAs levels were found. Saturated fatty acids play a negative role in long-term cognitive outcomes in stroke patients. The metabolic cascade of polyunsaturated fatty acids (n3 PUFA) and the synthesis of (AA) can be involved in pathogenesis of stroke-related cognitive impairment.

Analysis of 12/15-lipoxygenase metabolism of EPA and DHA with special attention to authentication of docosatrienes

A proposed beneficial impact of highly unsaturated “fish oil” fatty acids is their conversion by lipoxygenase (LOX) enzymes to specialized proresolving lipid mediators, including 12/15-LOX products from EPA and DHA. The transformations of DHA include formation of docosatrienes, named for the distinctive conjugated triene of the double bonds. To further the understanding of biosynthetic pathways and mechanisms, herein we meld together biosynthesis and NMR characterization of the unstable leukotriene A (LTA)-related epoxide intermediates formed by recombinant human 15-LOX-1, along with identification of the stable enzymatic products, and extend the findings into the 12/15-LOX metabolism in resident murine peritoneal macrophages. Oxygenation of EPA by 15-LOX-1 converts the initial 15S-hydroperoxide to 14S,15S-trans-epoxy-5Z,8Z,10E,12E,17Z-EPA (appearing as its 8,15-diol hydrolysis products) and mixtures of dihydroperoxy fatty acids, while mainly the epoxide hydrolysis products are evident in the murine cells. DHA also undergoes transformations to epoxides and dihydroperoxides by 15-LOX-1, resulting in a mixture of 10,17-dihydro(pero)xy derivatives (docosatrienes) and minor 7S,17S- and 14,17S-dihydroperoxides. The 10,17S-dihydroxy hydrolysis products of the LTA-related epoxide intermediate dominate the product profile in mouse macrophages, whereas (neuro)protectin D1, the leukotriene B₄-related derivative with trans,trans,cis conjugated triene, was undetectable. In this study, we emphasize the utility of UV spectral characteristics for product identification, being diagnostic of the different double bond configurations and hydroxy fatty acid functionality versus hydroperoxide. LC-MS is not definitive for configurational isomers. Secure identification is based on chromatographic retention times, comparison with authentic standards, and the highly distinctive UV spectra.

Pro-Resolving Mediator Annexin A1 Regulates Intracellular Ca2+ and Mucin Secretion in Cultured Goblet Cells Suggesting a New Use in Inflammatory Conjunctival Diseases

The amount of mucin secreted by conjunctival goblet cells is regulated to ensure the optimal level for protection of the ocular surface. Under physiological conditions lipid specialized pro-resolving mediators (SPM) are essential for maintaining tissue homeostasis including the conjunctiva. The protein Annexin A1 (AnxA1) can act as an SPM. We used cultured rat conjunctival goblet cells to determine if AnxA1 stimulates an increase in intracellular [Ca²⁺] ([Ca²⁺]_i) and mucin secretion and to identify the signaling pathways. The increase in [Ca²⁺]_i was determined using fura2/AM and mucin secretion was measured using an enzyme-linked lectin assay. AnxA1 stimulated an increase in [Ca²⁺]_i and mucin secretion that was blocked by the cell-permeant Ca²⁺ chelator BAPTA/AM and the ALX/FPR2 receptor inhibitor BOC2. AnxA1 increased [Ca²⁺]_i to a similar extent as the SPMs lipoxin A₄ and Resolvin (Rv) D1 and histamine. The AnxA1 increase in [Ca²⁺]_i and mucin secretion were inhibited by blocking the phospholipase C (PLC) pathway including PLC, the IP₃ receptor, the Ca²⁺/ATPase that causes the intracellular Ca²⁺ stores to empty, and blockade of Ca²⁺ influx. Inhibition of protein kinase C (PKC) and Ca²⁺/calmodulin-dependent protein kinase also decreased the AnxA1-stimulated increase in [Ca²⁺]_i and mucin secretion. In contrast inhibitors of ERK 1/2, phospholipase A₂ (PLA₂), and phospholipase D (PLD) did not alter AnxA1-stimulated increase in [Ca²⁺]_i, but did inhibit mucin secretion. Activation of protein kinase A did not decrease either the AnxA1-stimulated rise in [Ca²⁺]_i or secretion. We conclude that in health, AnxA1 contributes to the mucin layer of the tear film and ocular surface homeostasis by activating the PLC signaling pathway to increase [Ca²⁺]_i and stimulate mucin secretion and ERK1/2, PLA₂, and PLD to stimulate mucin secretion from conjunctival goblet cells.

New Perspectives in the Study of Intestinal Inflammation: Focus on the Resolution of Inflammation

Inflammation is an essential physiological process that is directed to the protection of the organism against invading pathogens or tissue trauma. Most of the existing knowledge related to inflammation is focused on the factors and mechanisms that drive the induction phase of this process. However, since the recognition that the resolution of the inflammation is an active and tightly regulated process, increasing evidence has shown the relevance of this process for the development of chronic inflammatory diseases, such as inflammatory bowel disease. For that reason, with this review, we aimed to summarize the most recent and interesting information related to the resolution process in the context of intestinal inflammation. We discussed the advances in the understanding of the pro-resolution at intestine level, as well as the new mediators with pro-resolutive actions that could be interesting from a therapeutic point of view.

Fish Oil for Inflammatory Bowel Disease: Panacea or Placebo?

Dietary supplements have increasingly gained popularity over the years not only to replete micronutrient deficiencies but for their use in treatment of disease. The popularity of dietary supplements for inflammatory bowel diseases (IBD) arises from their perceived ease of use, potential disease-modifying benefits, and perceived safety. Overall, randomized controlled trials have not consistently shown a benefit of fish oil for the maintenance of remission with Crohn's disease. The inconsistency of these findings highlights the need for more studies that are powered to clarify the context in which omega-3 fatty acids might have a role in the treatment algorithm of IBD.

Developments of specialized pro-resolving mediators in periodontitis

Resolution of inflammation plays an important part in maintaining homeostasis. It is an actively programmed progress involving multiple immune cells and mediators. Specialized pro-resolving mediators (SPMs) derived from Ω-3 polyunsaturated fatty acids include resolvins, protectins and maresins, and they exert abilities in the resolution of inflammation, host defense, organ protection, and tissue generation. Periodontitis is an inflammatory and destructive disease in the periodontal tissue initiated by dental plaque. Inadequate proinflammatory or proresolving responses, or the imbalance between the two, may contribute to the pathogenesis of the disease. Studies have shown that activating specialized receptors SPMs displayed multiple biological effects towards periodontitis, including resolution of inflammation, alveolar bone protection, periodontal tissue regeneration, and pathogen resistance. Thus, the relationship between SPM and periodontitis and the potentials and challenges in SPM application were reviewed.

Role of polyunsaturated fatty acids in ischemic stroke - A perspective of specialized pro-resolving mediators

Polyunsaturated fatty acids (PUFAs) have been proposed as beneficial for cardiovascular health. However, results from both epidemiological studies and clinical trials have been inconsistent, whereas most of the animal studies showed promising benefits of PUFAs in the prevention and treatment of ischemic stroke. In recent years, it has become clear that PUFAs are metabolized into various types of bioactive derivatives, including the specialized pro-resolving mediators (SPMs). SPMs exert multiple biofunctions, such as to limit excessive inflammatory responses, regulate lipid metabolism and immune cell functions, decrease production of pro-inflammatory factors, increase anti-inflammatory mediators, as well as to promote tissue repair and homeostasis. Inflammation has been recognised as a key contributor to the pathophysiology of acute ischemic stroke. Owing to their potent pro-resolving actions, SPMs are potential for development of novel anti-stroke therapy. In this review, we will summarize current knowledge of epidemiological studies, basic research and clinical trials concerning PUFAs in stroke prevention and treatment, with special attention to SPMs as the unsung heroes behind PUFAs.

Cytokine Storm and Failed Resolution in COVID-19: Taking a Cue from Multiple Sclerosis

INTRODUCTION

Excessive inflammatory responses and failed resolution are major common causes of tissue injury and organ dysfunction in a variety of diseases, including multiple sclerosis (MS), diabetes, and most recently, COVID-19, despite the distinct pathoetiology of the diseases. The promotion of the natural process of inflammatory resolution has been long recognized to improve functional recovery and disease outcomes effectively. To mitigate the excessive inflammation in MS, scientific investigations identified a group of derivatives of omega fatty acids, known as specialized pro-resolving lipid mediators (SPM) that have been significantly effective in treating preclinical disease models of MS.

METHODS

This chapter is based on our observations from MS. It is being increasingly deliberated that the ongoing COVID-19 infection induces severe cytokine storm that ultimately triggers rampant inflammation. The impact of infection and associated mortality is much higher in patients with co-morbid diseases. Also, reports suggest a better outcome in diabetic patients with reasonable glycemic control, which certainly hints towards a hidden role of anti-hyperglycemic drugs such as metformin in alleviating disease pathology through its anti-inflammatory feature. Notably, SPM and metformin share common therapeutic features in exerting a broad-spectrum anti-inflammatory activity in human patients with a superior safety profile.

RESULTS

When there is an immediate need to encounter the fast-rampant infection of COVID-19 and control the viral-infection associated morbid inflammatory cytokine storm causing severe organ damage, SPM and metformin should be seriously considered as a potential adjunctive treatment.

CONCLUSION

Given the fact that current treatment for COVID-19 is only supportive, global research is aimed at developing safe and effective therapeutic options that can result in a better clinical course in patients with comorbid conditions. Accordingly, taking a cue from our experiences in controlling robust inflammatory response in MS and diabetes by simultaneously inhibiting inflammatory process and stimulating its resolution, combinatorial therapy of metformin and SPM in COVID-19 holds significant promise in treating this global health crisis.

Exploring the molecular approach of COX and LOX in Alzheimer's and Parkinson's disorder

Neuroinflammation is well established biomarker for the major neurodegenerative like Alzheimer's disease (AD) and Parkinson's disease (PD). Cytokines/chemokines excite phospholipase A2 and cyclooxygenases (COX), facilitating the release of arachidonic acid (AA) and docosahexaenoic acid (DHA) from membrane glycerophospholipids, in which the former is oxidized to produce pro-inflammatory eicosanoids (prostaglandins, leukotrienes and thromboxane's), which intensify the neuroinflammatory events in the brain. Similarly, resolvins and neuroprotectins are the metabolized products of docosahexaenoic acid, which exert an inhibitory effect on the production of eicosanoids. Furthermore, an oxidized product of arachidonic acid, lipoxin, is generated via 5-lipoxygenase (5-LOX) pathway, and contributes to the resolution of inflammation, along with anti-inflammatory actions. Moreover, DHA and its lipid mediators inhibit neuroinflammatory responses by blocking NF-κB, inhibiting eicosanoid production, preventing cytokine secretion and regulating leukocyte trafficking. Various epidemiological studies reported, elevated levels of COX-2 enzyme in patients with AD and PD, indicating its role in progression of the disease. Similarly, enhanced levels of 5-LOX and 12/15-LOX in PD models represent their role brain disorders, where the former is expressed in AD patients and the latter exhibits it involvement in PD. The present review elaborates the role of AA, DHA, eicosanoids and docosanoids, along with COX and LOX pathway which provides an opportunity to the researchers to understand the role of these lipid mediators in neurological disorders (AD and PD). The information gathered from the review will aid in facilitating the development of appropriate therapeutic options targeting COX and LOX pathway.

Potential use of n-3 PUFAs to prevent oxidative stress-derived ototoxicity caused by platinum-based chemotherapy

Platinum-based compounds are widely used for the treatment of different malignancies due to their high effectiveness. Unfortunately, platinum-based treatment may lead to ototoxicity, an often-irreversible side effect without a known effective treatment and prevention plan. Platinum-based compound-related ototoxicity results mainly from the production of toxic levels of reactive oxygen species (ROS) rather than DNA-adduct formation, which has led to test strategies based on direct ROS scavengers to ameliorate hearing loss. However, favorable clinical results have been associated with several complications, including potential interactions with chemotherapy efficacy. To understand the contribution of the different cytotoxic mechanisms of platinum analogues on malignant cells and auditory cells, the particular susceptibility and response of both kinds of cells to molecules that potentially interfere with these mechanisms, is fundamental to develop innovative strategies to prevent ototoxicity without affecting antineoplastic effects. The n-3 long-chain polyunsaturated fatty acids (n-3 PUFAs) have been tried in different clinical settings, including with cancer patients. Nevertheless, their use to decrease cisplatin-induced ototoxicity has not been explored to date. In this hypothesis paper, we address the mechanisms of platinum compounds-derived ototoxicity, focusing on the differences between the effects of these compounds in neoplastic versus auditory cells. We discuss the basis for a strategic use of n-3 PUFAs to potentially protect auditory cells from platinum-derived injury without affecting neoplastic cells and chemotherapy efficacy.

May omega-3 fatty acid dietary supplementation help reduce severe complications in Covid-19 patients?

In around 10% of SARS-CoV-2 infected patients, coronavirus disease-2019 (Covid-19) symptoms are complicated with a severe lung damage called Acute Respiratory Distress Syndrome (ARDS), which is often lethal. ARDS is mainly associated with an uncontrolled overproduction of immune cells and cytokines, called "cytokine storm syndrome"; it appears 7-15 days following the onset of symptoms, leading to systemic inflammation and multiple organ failure. Because they are well-known metabolic precursors of specialized pro-resolving lipid mediators (SPMs), omega-3 long-chain polyunsaturated fatty acids (omega-3 LC-PUFAs) could help improve the resolution of the inflammatory balance, limiting therefore the level and duration of the critical inflammatory period. Omega-3 LC-PUFAs may also interact at different stages of the viral infection, notably on the virus entry and replication. In the absence of demonstrated treatment and while waiting for vaccine possibility, the use of omega-3 LC-PUFAs deserve therefore to be considered, based on previous clinical studies suggesting that omega-3 supplementation could improve clinical outcomes of critically ill patients at the acute phase of ARDS. In this context, it is crucial to remind that the omega-3 PUFA dietary intake levels in Western countries remains largely below the current recommendations, considering both the omega-3 precursor α-linolenic acid (ALA) and long chain derivatives such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). An optimized omega-3 PUFAs status could be helpful to prevent infectious diseases, including Covid-19.

The Role of Specialized Pro-Resolving Mediators in Cystic Fibrosis Airways Disease

Cystic Fibrosis (CF) is a recessive genetic disease due to mutations of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene encoding the CFTR chloride channel. The ion transport abnormalities related to CFTR mutation generate a dehydrated airway surface liquid (ASL) layer, which is responsible for an altered mucociliary clearance, favors infections and persistent inflammation that lead to progressive lung destruction and respiratory failure. The inflammatory response is normally followed by an active resolution phase to return to tissue homeostasis, which involves specialized pro-resolving mediators (SPMs). SPMs promote resolution of inflammation, clearance of microbes, tissue regeneration and reduce pain, but do not evoke unwanted immunosuppression. The airways of CF patients showed a decreased production of SPMs even in the absence of pathogens. SPMs levels in the airway correlated with CF patients' lung function. The prognosis for CF has greatly improved but there remains a critical need for more effective treatments that prevent excessive inflammation, lung damage, and declining pulmonary function for all CF patients. This review aims to highlight the recent understanding of CF airway inflammation and the possible impact of SPMs on functions that are altered in CF airways.

Cytokine and lipid metabolome effects of low-dose acetylsalicylic acid in critically ill patients with systemic inflammation: a pilot, feasibility, multicentre, randomised, placebo-controlled trial

OBJECTIVE

The systemic inflammatory response syndrome (SIRS) is a dysregulated response that contributes to critical illness. Adjunctive acetylsalicylic acid (ASA) treatment may offer beneficial effects by increasing the synthesis of specialised proresolving mediators (a subset of polyunsaturated fatty acid-derived lipid mediators).

DESIGN

Pilot, feasibility, multicentre, double-blind, randomised, placebo-controlled trial.

SETTING

Four interdisciplinary intensive care units (ICUs) in Australia.

PARTICIPANTS

Critically ill patients with SIRS.

INTERVENTIONS

ASA 100 mg 12-hourly or placebo, administered within 24 hours of ICU admission and continued until ICU day 7, discharge or death, whichever came first.

MAIN OUTCOME MEASURES

Interleukin-6 (IL-6) serum concentration at 48 hours after randomisation and, in a prespecified subgroup of patients, serum lipid mediator concentrations measured by mass spectrometry.

RESULTS

The trial was discontinued in December 2017 due to slow recruitment and after the inclusion of 48 patients. Compared with placebo, ASA did not decrease IL-6 serum concentration at 48 hours. In the 32 patients with analysis of lipid mediators, low-dose ASA increased the concentration of 15-hydroxyeicosatetraenoic acid, a proresolving precursor of lipoxin A4, and reduced the concentration of the proinflammatory cytochrome P-dependent mediators 17-HETE (hydroxyeicosatetraenoic acid), 18-HETE and 20-HETE. In the eicosapentaenoic acid pathway, ASA significantly increased the concentration of the anti-inflammatory mediators 17,18-DiHETE (dihydroxyeicosatetraenoic acid) and 14,15-DiHETE.

CONCLUSIONS

In ICU patients with SIRS, low-dose ASA did not significantly alter serum IL-6 concentrations, but it did affect plasma concentrations of certain lipid mediators. The ability to measure lipid mediators in clinical samples and to monitor the effect of ASA on their levels unlocks a potential area of biological investigation in critical care.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ACTRN 12614001165673).

Specialized Pro-Resolving Lipid Mediators: Emerging Therapeutic Candidates for Multiple Sclerosis

Multiple sclerosis (MS) is a neuroinflammatory disease in which unresolved and uncontrolled inflammation disrupts normal cellular homeostasis and leads to a pathological disease state. It has long been recognized that endogenously derived metabolic by-products of omega fatty acids, known as specialized pro-resolving lipid mediators (SPMs), are instrumental in resolving the pathologic inflammation. However, there is minimal data available on the functional status of SPMs in MS, despite the fact that MS presents a classical model of chronic inflammation. Studies to date indicate that dysfunction of the SPM biosynthetic pathway is responsible for their altered levels in patient-derived biofluids, which contributes to heightened inflammation and disease severity. Collectively, current findings suggest the contentious role of SPMs in MS due to variable outcomes in biological matrices across studies conducted so far, which could, in part, also be attributed to differences in population characteristics. It seems that SPMs have neuroprotective action on MS by exerting proresolving effects on brain microglia in its preclinical model; however, there are no reports demonstrating the direct effect of SPMs on oligodendrocytes or neurons. This reveals that "one size does not fit all" notion holds significance for MS in terms of the status of SPMs in other inflammatory conditions. The lack of clarity served as the impetus for this review, which is the first of its kind to summarize the relevant data regarding the role of SPMs in MS and the potential to target them for biomarker development and future alternative therapies for this disease. Understanding the mechanisms behind biological actions of SPMs as resolution mediators may prevent or even cure MS and other neurodegenerative pathologies.

Sex-mediated elevation of the specialized pro-resolving lipid mediator levels in a Sjögren's syndrome mouse model

Our previous results showed that the specialized pro-resolving mediator (SPM) Resolvin D1 (RvD1) promotes resolution of inflammation in salivary glands in non-obese diabetic (NOD)/ShiLtJ, a mouse model for Sjögren's syndrome (SS). Additionally, mice lacking the RvD1 receptor ALX/FPR2 show defective innate and adaptive immune responses in salivary glands. Particularly, ALX/FPR2 KO mice exhibit exacerbated inflammation in their salivary glands in response to systemic LPS treatment. Moreover, female ALX/FPR2 KO mice show increased autoantibody production and loss of salivary gland function with age. Together, these studies suggest that an underlying SPM dysregulation could be contributing to SS progression. Therefore, we investigated whether SPM production is altered in NOD/ShiLtJ using metabololipidomics and enzyme-linked immunosorbent assay (ELISA). Our results demonstrate that SPM levels were broadly elevated in plasma collected from NOD/ShiLtJ female mice after disease onset, whereas these drastic changes did not occur in male mice. Moreover, gene expression of enzymes involved in SPM biosynthesis were altered in submandibular glands (SMG) from NOD/ShiLtJ female mice after disease onset, with 5-LOX and 12/15-LOX being downregulated and upregulated, respectively. Despite this dysregulation, the abundances of the SPM products of these enzymes (ie, RvD1 and RvD2) were unaltered in freshly isolated SMG cells suggesting that other cell populations (eg, lymphocytes) may be responsible for the overabundance of SPMs that we observed. The elevation of SPMs noted here appeared to be sex mediated, meaning that it was observed only in one sex (females). Given that SS primarily affects females (roughly 90% of diagnosed cases), these results may provide some insights into the mechanisms underlying the observed sexual dimorphism.

Homocysteine and Asymmetrical Dimethylarginine in Diabetic Rats Treated with Docosahexaenoic Acid-Loaded Zinc Oxide Nanoparticles

Hyperglycemia, the hallmark of diabetes mellitus, is considered one of the endothelial dysfunction risk factors, the main reason of vascular complication. In this study, we aimed to evaluate homocysteine (Hcy) and asymmetrical dimethylarginine (ADMA) levels in diabetic rats and the possibility to attenuate the elevation of these two parameters by supplementation of docosahexaenoic acid (DHA) alone or loaded zinc oxide nanoparticles (ZnONPs) to improve endothelial dysfunction in streptozotocin (STZ)-induced diabetic rats. Forty male albino rats weighing 180-200 g were classified as control, diabetic, diabetic treated with DHA, and diabetic treated with DHA-loaded zinc oxide nanoparticles (DHA/ZnONPs) groups. Fasting blood glucose, insulin, ADMA, Hcy, and nitric oxide (NO) were estimated. Fatty acids (linoleic acid (LA), arachidonic acid (AA), DHA, α-linolenic acid (ALA), and oleic acid (OA)) were also evaluated by reversed phase HPLC using a UV detector. The results showed that fasting blood sugar, insulin resistance, LA, AA, OA, ADMA, and Hcy increased significantly in diabetic rats compared with control while fasting insulin, DHA, ALA, and NO decreased significantly in diabetic rats. In both treated groups, fasting blood sugar, insulin resistance, LA, AA, OA, ADMA, and Hcy significantly decreased as compared with the diabetic group while fasting insulin, DHA, ALA, and NO were significantly increased. In conclusion, DHA and DHA/ZnONP supplementation protect against diabetic complications and improve endothelial dysfunction as well as hyperhomocysteinemia in diabetes. DHA/ZnONP-treated group appeared more efficient than DHA alone.

Immuno-Resolving Ability of Resolvins, Protectins, and Maresins Derived from Omega-3 Fatty Acids in Metabolic Syndrome

Omega-3 fatty acid consumption has been suggested to be beneficial for the prevention of type 2 diabetes mellitus (T2DM). Its effects have been attributed to anti-inflammatory activity, with the inhibition of arachidonic acid metabolism playing a central role. However, a more recent view is that omega-3 fatty acids play an active role as the precursors of potent, specialized pro-resolving mediators (SPMs), such as resolvins, protectins, and maresins. Docosahexaenoic acid (DHA)- and eicosapentaenoic-acid-derived SPMs are identified in the adipose tissue but the levels of certain SPMs (e.g., protectin D1) are markedly reduced with obesity, suggesting adipose SPM deficiency, potentially resulting in unresolved inflammation. Supplementation of the biosynthetic intermediates of SPM (e.g., 17-hydroxy-DHA) or omega-3 fatty acids increases the level of adipose SPMs, reduces adipose inflammation (decrease in macrophage accumulation and change to less inflammatory macrophages), and enhances insulin sensitivity. The findings from studies using rodent obesity models must be translated to humans. It will be important to further elucidate the underlying mechanisms by which obesity reduces the levels of and the sensitivity to SPM in adipose tissues. This will enable the development of nutrition therapy to enhance the effects of omega-3 fatty acids in the prevention and/or treatment of T2DM.

Effect of High-Dose Marine Omega-3 Fatty Acids on Atherosclerosis: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

A recent randomized controlled trial (RCT), the Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial (REDUCE-IT), reported that high-dose marine omega-3 fatty acids (OM3) significantly reduce cardiovascular disease (CVD) outcomes, yet the mechanisms responsible for this benefit remain unknown. To test the hypothesis that high-dose OM3 is anti-atherosclerotic, we performed a systematic review and meta-analysis of RCT of high-dose OM3 on atherosclerosis. The protocol of this systematic review was registered with PROSPERO (CRD42019125566). PubMed, Embase, Cochran Central Register for Controlled Trials, and Clinicaltrials.gov databases were searched using the following criteria: adult participants, high-dose OM3 (defined as ≥3.0 g/day, or in Japan 1.8 g/day and purity ≥90%) as the intervention, changes in atherosclerosis as the outcome, and RCTs with an intervention duration of ≥6 months. A random-effects meta-analysis was used to pool estimates across studies. Among the 598 articles retrieved, six articles met our criteria. Four RCTs evaluated atherosclerosis in the coronary and two in the carotid arteries. High-dose OM3 significantly slowed the progression of atherosclerosis (standardized mean difference −1.97, 95% confidence interval −3.01, −0.94, p < 0.001). The results indicate that anti-atherosclerotic effect of high-dose OM3 is one potential mechanism in reducing CVD outcomes demonstrated in the REDUCE-IT trial.

N-3 fatty acids as preventive and therapeutic agents in attenuating PCOS complications

To our knowledge, in spite of several trials exploring the beneficial effect of n-3 polyunsaturated fatty acids (PUFA) on polycystic ovary syndrome (PCOS), no comprehensive evidence has investigated the effects of n-3 PUFA consumption on PCOS complications. Therefore, our aim was to conduct a review to investigate the possible effect and related mechanisms. A comprehensive systematic search was conducted in Embase, MEDLINE/PubMed, Google Scholar, and SCOPUS, to identify studies investigating n-3 fatty acids as a preventative or therapeutic agent for the attenuation of PCOS complications. Subsequently, the impact of omega-3 on PCOS, omega-3 and inflammation, omega-3 and insulin resistance, omega-3 and adipokines, omega-3 and lipid metabolism, omega-3 and endothelial function and omega-3 and hormonal factors were discussed. There are multiple mechanisms by which n-3 PUFAs may exert their beneficial effects on PCOS, including anti-obesity, glycemic and hormonal hemostasis, anti-inflammatory, regulation of adipokine production and enhancement of endothelial function.N-3 PUFAs are a promising agent in relieving complications associated with PCOS. Although most of the studies in patients with PCOS reported an improvement in most complications after administration of omega-3 supplements, there is a distinct dearth of studies investigating the dietary intake of these types of fatty acids. Moreover, favorable effects regarding the improvement of dyslipidemia, regulation of adipokines, regulation of hormonal factors and enhancement of endothelial function are limited. Therefore, more trials are warranted to investigate palatable mechanisms for clarifying the metabolic and hormonal effects of these agents in PCOS.

Arachidonic Acid and Docosahexaenoic Acid Metabolites in the Airways of Adults With Cystic Fibrosis: Effect of Docosahexaenoic Acid Supplementation

Cystic fibrosis (CF) is an autosomal recessive disorder, caused by genetic mutations in CF transmembrane conductance regulator protein. Several reports have indicated the presence of specific fatty acid alterations in CF patients, most notably decreased levels of plasmatic and tissue docosahexaenoic acid (DHA), the precursor of specialized pro-resolving mediators. We hypothesized that DHA supplementation could restore the production of DHA-derived products and possibly contribute to a better control of the chronic pulmonary inflammation observed in CF subjects. Sputum samples from 15 CF and 10 chronic obstructive pulmonary disease (COPD) subjects were collected and analyzed by LC/MS/MS, and blood fatty acid were profiled by gas chromatography upon lipid extraction and transmethylation. Interestingly, CF subjects showed increased concentrations of leukotriene B₄ (LTB₄), prostaglandin E₂ (PGE₂), and 15-hydroxyeicosatetraenoic acid (15-HETE), when compared with COPD patients, whereas the concentrations of DHA metabolites did not differ between the two groups. After DHA supplementation, not only DHA/arachidonic acid (AA) ratio and highly unsaturated fatty acid index were significantly increased in the subjects completing the study (p < 0.05) but also a reduction in LTB₄ and 15-HETE was observed, together with a tendency for a decrease in PGE_2, and an increase in 17-hydroxy-docosahexaenoic acid (17OH-DHA) levels. At the end of the washout period, LTB₄, PGE₂, 15-HETE, and 17OH-DHA showed a trend to return to baseline values. In addition, 15-HETE/17OH-DHA ratio in the same sample significantly decreased after DHA supplementation (p < 0.01) when compared with baseline. In conclusion, our results show here that in CF patients, an impairment in fatty acid metabolism, characterized by increased AA-derived metabolites and decreased DHA-derived metabolites, could be partially corrected by DHA supplementation.