Comparison of the dietary omega-3 fatty acids impact on murine psoriasis-like skin inflammation and associated lipid dysfunction.

Persistent skin inflammation and impaired resolution are the main contributors to psoriasis and associated cardiometabolic complications. Omega-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), are known to exert beneficial effects on inflammatory response and lipid function. However, a specific role of omega-3 PUFAs in psoriasis and accompanied pathologies are still a matter of debate. Here, we carried out a direct comparison between EPA and DHA 12 weeks diet intervention treatment of psoriasis-like skin inflammation in the K14-Rac1V12 mouse model. By utilizing sensitive techniques, we targeted EPA- and DHA-derived specialized pro-resolving lipid mediators and identified tightly connected signaling pathways by RNA sequencing. Treatment with experimental diets significantly decreased circulating pro-inflammatory cytokines and bioactive lipid mediators, altered psoriasis macrophage phenotypes and genes of lipid oxidation. The superficial role of these changes was related to DHA treatment and included increased levels of resolvin D5, protectin DX and maresin 2 in the skin. EPA treated mice had less pronounced effects but demonstrated a decreased skin accumulation of prostaglandin E2 and thromboxane B2. These results indicate that modulating psoriasis skin inflammation with the omega-3 PUFAs may have clinical significance and DHA treatment might be considered over EPA in this specific disease.

Mast cells participate in smooth muscle cell reprogramming and atherosclerotic plaque calcification.

BACKGROUND: Calcification, a key feature of advanced human atherosclerosis, is positively associated with vascular disease burden and adverse events. We showed that macrocalcification can be a stabilizing factor for carotid plaque molecular biology, due to inverse association with immune processes. Mast cells (MCs) are important contributors to plaque instability, but their relationship with macrocalcification is unexplored. With a hypothesis that MC activation negatively associates with carotid plaque macrocalcification, we aimed to investigate the link between MCs and carotid plaque vulnerability, and study MC role in plaque calcification via smooth muscle cells (SMCs). METHODS: Pre-operative computed tomography angiographies of patients (n = 40) undergoing surgery for carotid stenosis were used to characterize plaque morphology. Plaque microarrays (n = 40 and n = 126) were used for bioinformatic deconvolution of immune cell populations. Tissue microarrays (n = 103) were used to histologically validate the contribution of activated and resting MCs in plaques. RESULTS: Activated MCs and their typical markers were negatively correlated with macrocalcification. The ratio of activated vs. resting MCs was increased in low-calcified plaques from symptomatic patients. There was no modulating effect of medication on MC ratios. In vitro experiments showed that SMC calcification attenuated MC activation, while both active and resting MCs stimulated SMC calcification and induced dedifferentiation towards a pro-inflammatory-, osteochondrocyte-like phenotype, without modulating their migro-proliferative function. CONCLUSIONS: Integrative analyses from human plaques showed that MC activation is inversely associated with macrocalcification and positively with parameters of plaque vulnerability. Mechanistically, MCs induce SMC osteogenic reprograming, while matrix calcification in turn attenuates MC activation, offering new therapeutic avenues for exploration.

Decreased oxidative stress and altered urinary oxylipidome by intravenous omega-3 fatty acid emulsion in a randomized controlled trial of older subjects hospitalized for COVID-19.

Proinflammatory bioactive lipid mediators and oxidative stress are increased in coronavirus disease 2019 (COVID-19). The randomized controlled single-blind trial COVID-Omega-F showed that intravenous omega-3 polyunsaturated fatty acids (n-3 PUFA) shifted the plasma lipid signature of COVID-19 towards increased proresolving precursor levels and decreased leukotoxin diols, associated with a beneficial immunodulatory response. The present study aimed to determine the effects of n-3 PUFA on the urinary oxylipidome and oxidative stress in COVID-19. From the COVID-Omega-F trial, 20 patients hospitalized for COVID-19 had available serial urinary samples collected at baseline, after 24-48 h, and after completing 5 days treatment with one daily intravenous infusion (2 mL/kg) of either placebo (NaCl; n = 10) or a lipid emulsion containing 10 g of n-3 PUFA per 100 mL (n = 10). Urinary eicosanoids and isoprostanes were analyzed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Erythrocytes obtained at the different time-points from n = 10 patients (n = 5 placebo and n = 5 n-3 PUFA) were used for determination of reactive oxygen species. Intravenous n-3 PUFA emulsion administration altered eicosanoid metabolites towards decreased levels for mediators of inflammation and thrombosis, and increased levels of the endothelial function mediator prostacyclin. Furthermore, non-enzymatic metabolism was skewed towards n-3 PUFA-derived metabolites with potential anti-inflammatory and pro-resolving effects. The oxidative stress marker 15-F2t-isoprostane was significantly lower in patients receiving n-3 PUFA treatment, who also exhibited significantly decreased erythrocyte oxidative stress compared with placebo-treated patients. These findings point to additional beneficial effects of intravenous n-3 PUFA emulsion treatment through a beneficial oxylipin profile and decreased oxidative stress in COVID-19.

The resolvin D2 - GPR18 axis is expressed in human coronary atherosclerosis and transduces atheroprotection in apolipoprotein E deficient mice.

Chronic inflammation in atherosclerosis reflects a failure in the resolution of inflammation. Pro-resolving lipid mediators derived from omega-3 fatty acids reduce the development of atherosclerosis in murine models. The aim of the present study was to decipher the role of the specialized proresolving mediator (SPM) resolvin D2 (RvD2) in atherosclerosis and its signaling through the G-protein coupled receptor (GPR) 18. The ligand and receptor were detected in human coronary arteries in relation to the presence of atherosclerotic lesions and its cellular components. Importantly, RvD2 levels were significantly higher in atherosclerotic compared with healthy human coronary arteries. Furthermore, apolipoprotein E (ApoE) deficient hyperlipidemic mice were treated with either RvD2 or vehicle in the absence and presence of the GPR18 antagonist O-1918. RvD2 significantly reduced atherosclerosis, necrotic core area, and pro-inflammatory macrophage marker expression. RvD2 in addition enhanced macrophage phagocytosis. The beneficial effects of RvD2 were not observed in the presence of O-1918. Taken together, these results provide evidence of atheroprotective pro-resolving signalling through the RvD2-GPR18 axis.

Vagus nerve stimulation promotes resolution of inflammation by a mechanism that involves Alox15 and requires the α7nAChR subunit.

Nonresolving inflammation underlies a range of chronic inflammatory diseases, and therapeutic acceleration of resolution of inflammation may improve outcomes. Neural reflexes regulate the intensity of inflammation (for example, through signals in the vagus nerve), but whether activation of the vagus nerve promotes the resolution of inflammation in vivo has been unknown. To investigate this, mice were subjected to electrical vagus nerve stimulation (VNS) or sham surgery at the cervical level followed by zymosan-induced peritonitis. The duration of inflammation resolution was significantly reduced and efferocytosis was significantly increased in mice treated with VNS as compared with sham. Lipid mediator (LM) metabololipidomics revealed that mice treated with VNS had higher levels of specialized proresolving mediators (SPMs), particularly from the omega-3 docosahexaenoic (DHA) and docosapentaenoic (n-3 DPA) metabolomes, in peritoneal exudates. VNS also shifted the ratio between proinflammatory and proresolving LMs toward a proresolving profile, but this effect by VNS was inverted in mice deficient in 12/15-lipoxgenase (Alox15), a key enzyme in this SPM biosynthesis. The significant VNS-mediated reduction of neutrophil numbers in peritoneal exudates was absent in mice deficient in the cholinergic α7-nicotinic acetylcholine receptor subunit (α7nAChR), an essential component of the inflammatory reflex. Thus, VNS increased local levels of SPM and accelerated resolution of inflammation in zymosan-induced peritonitis by a mechanism that involves Alox15 and requires the α7nAChR.

Osteomodulin attenuates smooth muscle cell osteogenic transition in vascular calcification.

RATIONALE: Vascular calcification is a prominent feature of late-stage diabetes, renal and cardiovascular disease (CVD), and has been linked to adverse events. Recent studies in patients reported that plasma levels of osteomodulin (OMD), a proteoglycan involved in bone mineralisation, associate with diabetes and CVD. We hypothesised that OMD could be implicated in these diseases via vascular calcification as a common underlying factor and aimed to investigate its role in this context. METHODS AND RESULTS: In patients with chronic kidney disease, plasma OMD levels correlated with markers of inflammation and bone turnover, with the protein present in calcified arterial media. Plasma OMD also associated with cardiac calcification and the protein was detected in calcified valve leaflets by immunohistochemistry. In patients with carotid atherosclerosis, circulating OMD was increased in association with plaque calcification as assessed by computed tomography. Transcriptomic and proteomic data showed that OMD was upregulated in atherosclerotic compared to control arteries, particularly in calcified plaques, where OMD expression correlated positively with markers of smooth muscle cells (SMCs), osteoblasts and glycoproteins. Immunostaining confirmed that OMD was abundantly present in calcified plaques, localised to extracellular matrix and regions rich in α-SMA+ cells. In vivo, OMD was enriched in SMCs around calcified nodules in aortic media of nephrectomised rats and in plaques from ApoE-/- mice on warfarin. In vitro experiments revealed that OMD mRNA was upregulated in SMCs stimulated with IFNγ, BMP2, TGFß1, phosphate and ß-glycerophosphate, and by administration of recombinant human OMD protein (rhOMD). Mechanistically, addition of rhOMD repressed the calcification process of SMCs treated with phosphate by maintaining their contractile phenotype along with enriched matrix organisation, thereby attenuating SMC osteoblastic transformation. Mechanistically, the role of OMD is exerted likely through its link with SMAD3 and TGFB1 signalling, and interplay with BMP2 in vascular tissues. CONCLUSION: We report a consistent association of both circulating and tissue OMD levels with cardiovascular calcification, highlighting the potential of OMD as a clinical biomarker. OMD was localised in medial and intimal α-SMA+ regions of calcified cardiovascular tissues, induced by pro-inflammatory and pro-osteogenic stimuli, while the presence of OMD in extracellular environment attenuated SMC calcification.

The resolvin D1 receptor GPR32 transduces inflammation resolution and atheroprotection.

Chronic inflammation is a hallmark of atherosclerosis and results from an imbalance between proinflammatory and proresolving signaling. The human GPR32 receptor, together with the ALX/FPR2 receptor, transduces biological actions of several proresolving mediators that stimulate resolution of inflammation. However, since no murine homologs of the human GPR32 receptor exist, comprehensive in vivo studies are lacking. Using human atherosclerotic lesions from carotid endarterectomies and creating a transgenic mouse model expressing human GPR32 on a Fpr2×ApoE double-KO background (hGPR32myc×Fpr2-/-×Apoe-/-), we investigated the role of GPR32 in atherosclerosis and self-limiting acute inflammation. GPR32 mRNA was reduced in human atherosclerotic lesions and correlated with the immune cell markers ARG1, NOS2, and FOXP3. Atherosclerotic lesions, necrotic core, and aortic inflammation were reduced in hGPR32mycTg×Fpr2-/-×Apoe-/- transgenic mice as compared with Fpr2-/-×Apoe-/- nontransgenic littermates. In a zymosan-induced peritonitis model, the hGPR32mycTg×Fpr2-/-×Apoe-/- transgenic mice had reduced inflammation at 4 hours and enhanced proresolving macrophage responses at 24 hours compared with nontransgenic littermates. The GPR32 agonist aspirin-triggered resolvin D1 (AT-RvD1) regulated leukocyte responses, including enhancing macrophage phagocytosis and intracellular signaling in hGPR32mycTg×Fpr2-/-×Apoe-/- transgenic mice, but not in Fpr2-/-×Apoe-/- nontransgenic littermates. Together, these results provide evidence that GPR32 regulates resolution of inflammation and is atheroprotective in vivo.

Omega-3 Polyunsaturated Fatty Acids Decrease Aortic Valve Disease Through the Resolvin E1 and ChemR23 Axis.

BACKGROUND: Aortic valve stenosis (AVS), which is the most common valvular heart disease, causes a progressive narrowing of the aortic valve as a consequence of thickening and calcification of the aortic valve leaflets. The beneficial effects of omega-3 polyunsaturated fatty acids (n-3 PUFAs) in cardiovascular prevention have recently been demonstrated in a large randomized, controlled trial. In addition, n-3 PUFAs serve as the substrate for the synthesis of specialized proresolving mediators, which are known by their potent beneficial anti-inflammatory, proresolving, and tissue-modifying properties in cardiovascular disease. However, the effects of n-3 PUFA and specialized proresolving mediators on AVS have not yet been determined. The aim of this study was to identify the role of n-3 PUFA-derived specialized proresolving mediators in relation to the development of AVS. METHODS: Lipidomic and transcriptomic analyses were performed in human tricuspid aortic valves. Apoe-/- mice and wire injury in C57BL/6J mice were used as models for mechanistic studies. RESULTS: We found that n-3 PUFA incorporation into human stenotic aortic valves was higher in noncalcified regions compared with calcified regions. Liquid chromatography tandem mass spectrometry-based lipid mediator lipidomics identified that the n-3 PUFA-derived specialized proresolving mediator resolvin E1 was dysregulated in calcified regions and acted as a calcification inhibitor. Apoe-/- mice expressing the Caenorhabditis elegans Fat-1 transgene (Fat-1tg×Apoe-/-), which enables the endogenous synthesis of n-3 PUFA and increased valvular n-3 PUFA content, exhibited reduced valve calcification, lower aortic valve leaflet area, increased M2 macrophage polarization, and improved echocardiographic parameters. Finally, abrogation of the resolvin E1 receptor ChemR23 enhanced disease progression, and the beneficial effects of Fat-1tg were abolished in the absence of ChemR23. CONCLUSIONS: n-3 PUFA-derived resolvin E1 and its receptor ChemR23 emerge as a key axis in the inhibition of AVS progression and may represent a novel potential therapeutic opportunity to be evaluated in patients with AVS.

Stimulating the Resolution of Inflammation Through Omega-3 Polyunsaturated Fatty Acids in COVID-19: Rationale for the COVID-Omega-F Trial.

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). SARS-CoV-2 triggers an immune response with local inflammation in the lung, which may extend to a systemic hyperinflammatory reaction. Excessive inflammation has been reported in severe cases with respiratory failure and cardiovascular complications. In addition to the release of cytokines, referred to as cytokine release syndrome or "cytokine storm," increased pro-inflammatory lipid mediators derived from the omega-6 polyunsaturated fatty acid (PUFA) arachidonic acid may cause an "eicosanoid storm," which contributes to the uncontrolled systemic inflammation. Specialized pro-resolving mediators, which are derived from omega-3 PUFA, limit inflammatory reactions by an active process called resolution of inflammation. Here, the rationale for omega-3 PUFA supplementation in COVID-19 patients is presented along with a brief overview of the study protocol for the trial "Resolving Inflammatory Storm in COVID-19 Patients by Omega-3 Polyunsaturated Fatty Acids - A single-blind, randomized, placebo-controlled feasibility study" (COVID-Omega-F). EudraCT: 2020-002293-28; clinicaltrials.gov: NCT04647604.

The resolution of inflammation through omega-3 fatty acids in atherosclerosis, intimal hyperplasia, and vascular calcification.

Omega-3 fatty acids serve as the substrate for the formation of a group of lipid mediators that mediate the resolution of inflammation. The cardiovascular inflammatory response in atherosclerosis and vascular injury is characterized by a failure in the resolution of inflammation, resulting in a chronic inflammatory response. The proresolving lipid mediator resolvin E1 (RvE1) is formed by enzymatic conversion of the omega-3 fatty acid eicosapentaenoic acid (EPA), and signals resolution of inflammation through its receptor ChemR23. Importantly, the resolution of cardiovascular inflammation is an active, multifactorial process that involves modulation of the immune response, direct actions on the vascular wall, as well as close interactions between macrophages and vascular smooth muscle cells. Promoting anti-atherogenic signalling through the stimulation of endogenous resolution of inflammation pathways may provide a novel therapeutic strategy in cardiovascular prevention.

ERV1/ChemR23 Signaling Protects Against Atherosclerosis by Modifying Oxidized Low-Density Lipoprotein Uptake and Phagocytosis in Macrophages.

BACKGROUND: In addition to enhanced proinflammatory signaling, impaired resolution of vascular inflammation plays a key role in atherosclerosis. Proresolving lipid mediators formed through the 12/15 lipoxygenase pathways exert protective effects against murine atherosclerosis. n-3 Polyunsaturated fatty acids, including eicosapentaenoic acid (EPA), serve as the substrate for the formation of lipid mediators, which transduce potent anti-inflammatory and proresolving actions through their cognate G-protein-coupled receptors. The aim of this study was to identify signaling pathways associated with EPA supplementation and lipid mediator formation that mediate atherosclerotic disease progression. METHODS: Lipidomic plasma analysis were performed after EPA supplementation in Apoe-/- mice. Erv1/Chemr23-/- xApoe-/- mice were generated for the evaluation of atherosclerosis, phagocytosis, and oxidized low-density lipoprotein uptake. Histological and mRNA analyses were done on human atherosclerotic lesions. RESULTS: Here, we show that EPA supplementation significantly attenuated atherosclerotic lesion growth induced by Western diet in Apoe-/- mice and was associated with local cardiovascular n-3 enrichment and altered lipoprotein metabolism. Our systematic plasma lipidomic analysis identified the resolvin E1 precursor 18-monohydroxy EPA as a central molecule formed during EPA supplementation. Targeted deletion of the resolvin E1 receptor Erv1/Chemr23 in 2 independent hyperlipidemic murine models was associated with proatherogenic signaling in macrophages, increased oxidized low-density lipoprotein uptake, reduced phagocytosis, and increased atherosclerotic plaque size and necrotic core formation. We also demonstrate that in macrophages the resolvin E1-mediated effects in oxidized low-density lipoprotein uptake and phagocytosis were dependent on Erv1/Chemr23. When analyzing human atherosclerotic specimens, we identified ERV1/ChemR23 expression in a population of macrophages located in the proximity of the necrotic core and demonstrated augmented ERV1/ChemR23 mRNA levels in plaques derived from statin users. CONCLUSIONS: This study identifies 18-monohydroxy EPA as a major plasma marker after EPA supplementation and demonstrates that the ERV1/ChemR23 receptor for its downstream mediator resolvin E1 transduces protective effects in atherosclerosis. ERV1/ChemR23 signaling may represent a previously unrecognized therapeutic pathway to reduce atherosclerotic cardiovascular disease.

Resolvin D3 multi-level proresolving actions are host protective during infection.

Resolution of infection and inflammation is governed by innate immune cells. The resolvin family of n-3 mediators produced by resolving exudates stimulates clearance of neutrophils and attenuates pro-inflammatory signals. Using metabololipidomics, endogenous resolvin D3 (RvD3) was identified in self-resolving exudates during active E. coli infection. Through a new, independent synthetic route for RvD3, we matched endogenous and synthetic RvD3 and determined that RvD3 (ng doses) potently reduced the resolution interval (Ri) by ~4.5h during E. coli peritonitis after administration at peak inflammation (Tmax=12h) and increased leukocyte phagocytosis of E. coli and neutrophils as well as reduced proinflammatory cytokines, chemokines, MMP-2 and MMP-9. At pM-nM concentrations, RvD3 also enhanced human macrophage efferocytosis and bacterial phagocytosis, increased neutrophil bacterial phagocytosis and intracellular ROS generation, and reduced human platelet-PMN aggregation. These results provide additional evidence for potent RvD3 immunoresolvent actions in host defense, host protection and antimicrobial defense.

Resolution of Inflammation Through the Lipoxin and ALX/FPR2 Receptor Pathway Protects Against Abdominal Aortic Aneurysms.

An abdominal aortic aneurysm (AAA) is a progressive aortic dilation that may lead to rupture, which is usually lethal. This study identifies the state of failure in the resolution of inflammation by means of decreased expression of the pro-resolving receptor A lipoxin/formyl peptide receptor 2 (ALX/FPR2) in the adventitia of human AAA lesions. Mimicking this condition by genetic deletion of the murine ALX/FPR2 ortholog in hyperlipidemic mice exacerbated the aortic dilation induced by angiotensin II infusion, associated with decreased vascular collagen and increased inflammation. The authors also identified key roles of lipoxin formation through 12/15-lipoxygenase and neutrophil p38 mitogen-activated protein kinase. In conclusion, this study established pro-resolving signaling by means of the ALX/FPR2 receptor in aneurysms and vascular inflammation.

Aspirin-triggered lipoxin A4 inhibits atherosclerosis progression in apolipoprotein E-/- mice.

BACKGROUND AND PURPOSE: Atherosclerosis is characterized by a chronic non-resolving inflammation in the arterial wall. Aspirin-triggered lipoxin A4 (ATL) is a potent anti-inflammatory mediator, involved in the resolution of inflammation. However, the therapeutic potential of immune targeting by means of ATL in atherosclerosis has not previously been explored. The aim of the present study was to determine the effects of ATL and its receptor Fpr2 on atherosclerosis development and progression in apolipoprotein E deficient (ApoE-/- ) mice. EXPERIMENTAL APPROACH: ApoE-/-  × Fpr2+/+ and ApoE-/-  × Fpr2-/- mice were generated. Four-week-old mice fed a high-fat diet for 4 weeks and 16-week-old mice fed chow diet received osmotic pumps containing either vehicle or ATL for 4 weeks. Atherosclerotic lesion size and cellular composition were measured in the aortic root and thoracic aorta. Lipid levels and leukocyte counts were measured in blood and mRNA was isolated from abdominal aorta and spleen. KEY RESULTS: ATL blocked atherosclerosis progression in the aortic root and thoracic aorta of ApoE-/- mice. In addition, ATL reduced macrophage infiltration and apoptotic cells in atherosclerotic lesions. The mRNA levels of several cytokines and chemokines in the spleen and aorta were reduced by ATL, whereas circulating leukocyte levels were unchanged. The ATL-induced athero-protection was absent in ApoE-/- mice lacking the Fpr2 receptor. CONCLUSION AND IMPLICATIONS: ATL blocked atherosclerosis progression by means of an Fpr2-mediated reduced local and systemic inflammation. These results suggest this anti-inflammatory and pro-resolving agent has therapeutic potential for the treatment of atherosclerosis. LINKED ARTICLES: This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.

Vagal Regulation of Group 3 Innate Lymphoid Cells and the Immunoresolvent PCTR1 Controls Infection Resolution.

Uncovering mechanisms that control immune responses in the resolution of bacterial infections is critical for the development of new therapeutic strategies that resolve infectious inflammation without unwanted side effects. We found that disruption of the vagal system in mice delayed resolution of Escherichia coli infection. Dissection of the right vagus decreased peritoneal group 3 innate lymphoid cell (ILC3) numbers and altered peritoneal macrophage responses. Vagotomy resulted in an inflammatory peritoneal lipid mediator profile characterized by reduced concentrations of pro-resolving mediators, including the protective immunoresolvent PCTR1, along with elevated inflammation-initiating eicosanoids. We found that acetylcholine upregulated the PCTR biosynthetic pathway in ILC3s. Administration of PCTR1 or ILC3s to vagotomized mice restored tissue resolution tone and host responses to E. coli infections. Together these findings elucidate a host protective mechanism mediated by ILC3-derived pro-resolving circuit, including PCTR1, that is controlled by local neuronal output to regulate tissue resolution tone and myeloid cell responses.

Resolvin D3 Is Dysregulated in Arthritis and Reduces Arthritic Inflammation.

Uncontrolled inflammation is a unifying component of many chronic inflammatory diseases, such as arthritis. Resolvins (Rvs) are a new family from the endogenous specialized proresolving mediators (SPMs) that actively stimulate resolution of inflammation. In this study, using lipid mediator metabololipidomics with murine joints we found a temporal regulation of endogenous SPMs during self-resolving inflammatory arthritis. The SPMs present in self-resolving arthritic joints include the D-series Rvs, for example, RvD1, RvD2, RvD3, and RvD4. Of note, RvD3 levels were reduced in inflamed joints from mice with delayed-resolving arthritis when compared with self-resolving inflammatory arthritis. RvD3 was also reduced in serum from rheumatoid arthritis patients compared with healthy controls. RvD3 administration reduced joint leukocytes as well as paw joint eicosanoids, clinical scores, and edema. Taken together, these findings provide evidence for dysregulated endogenous RvD3 levels in inflamed paw joints and its potent actions in reducing murine arthritis.

Proresolving and cartilage-protective actions of resolvin D1 in inflammatory arthritis.

Rheumatoid arthritis (RA) is a debilitating disease characterized by persistent accumulation of leukocytes within the articular cavity and synovial tissue. Metabololipidomic profiling of arthritic joints from omega-3 supplemented mice identified elevated levels of specialized proresolving lipid mediators (SPM) including resolvin D1 (RvD1). Profiling of human RA synovial fluid revealed physiological levels of RvD1, which - once applied to human neutrophils - attenuated chemotaxis. These results prompted analyses of the antiarthritic properties of RvD1 in a model of murine inflammatory arthritis. The stable epimer 17R-RvD1 (100 ng/day) significantly attenuated arthritis severity, cachexia, hind-paw edema, and paw leukocyte infiltration and shortened the remission interval. Metabololipidomic profiling in arthritic joints revealed 17R-RvD1 significantly reduced PGE2 biosynthesis, while increasing levels of protective SPM. Molecular analyses indicated that 17R-RvD1 enhanced expression of genes associated with cartilage matrix synthesis, and direct intraarticular treatment induced chondroprotection. Joint protective actions of 17R-RvD1 were abolished in RvD1 receptor-deficient mice termed ALX/fpr2/3-/- . These investigations open new therapeutic avenues for inflammatory joint diseases, providing mechanistic substance for the benefits of omega-3 supplementation in RA.