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Resolution of acute inflammation is an active process orchestrated by endogenous mediators and mechanisms pivotal in host defense and homeostasis. The macrophage mediator in resolving inflammation, maresin 1 (MaR1), is a potent immunoresolvent, stimulating resolution of acute inflammation and organ protection. Using an unbiased screening of greater than 200 GPCRs, we identified MaR1 as a stereoselective activator for human leucine-rich repeat containing G protein–coupled receptor 6 (LGR6), expressed in phagocytes. MaR1 specificity for recombinant human LGR6 activation was established using reporter cells expressing LGR6 and functional impedance sensing. MaR1-specific binding to LGR6 was confirmed using (3)H-labeled MaR1. With human and mouse phagocytes, MaR1 (0.01–10 nM) enhanced phagocytosis, efferocytosis, and phosphorylation of a panel of proteins including the ERK and cAMP response element-binding protein. These MaR1 actions were significantly amplified with LGR6 overexpression and diminished by gene silencing in phagocytes. Thus, we provide evidence for MaR1 as an endogenous activator of human LGR6 and a novel role of LGR6 in stimulating MaR1’s key proresolving functions of phagocytes.

Introduction: Polycystic Ovary Syndrome (PCOS) is an endocrinologic disorder that affects 5-15 % of women of their reproductive age and is a frequent cause of infertility. Major symptoms include hyperandrogenism, ovulatory dysfunction, a characteristic multi-follicular morphology of the ovary, an elevated ratio of LH/FSH, and often obesity and/or insulin resistance. PCOS also represents a state of chronic low-grade inflammation that is closely interlinked with the metabolic features. Inflammatory processes consist of the acute inflammatory response and resolution processes initiated concomitantly. "Classical" pro-inflammatory lipid mediators like prostaglandins (PG), leukotrienes (LT), or thromboxanes (TX) are derived from arachidonic acid (AA) and are crucial for the initial response. Resolution processes are driven by four families of so-called specialized pro-resolving mediators (SPMs): resolvins, maresins, lipoxins, and protectins. SPM biosynthesis starts from the essential polyunsaturated fatty acids DHA, DPA, or EPA via certain hydroxylated intermediates (18-HEPE, 17-HDHA, 14-HDHA). The present study aimed to establish lipid mediator profiles of PCOS patients compared to healthy women to identify differences in their resolutive and pro-inflammatory lipid parameters. Material and Methods: Blood samples were taken (20 ml), separated into plasma and serum, and analyzed by HPLC/MS-QQQ. Fifteen female patients (18-45 years) were diagnosed with PCOS according to Rotterdam criteria, and five healthy women, as comparator group, were recruited for the study. The main outcome measures were: Pro-inflammatory lipid mediators (PG, LT, TX) and their precursor AA; SPMs (Resolvins, Maresins, Protectins, Lipoxins), their precursors EPA, DHA, DPA, and their active biosynthesis pathway intermediates (18-HEPE, 17-HDHA, 14-HDHA). Ratio [(sum of pro-inflammatory molecules)/sum of SPMs]. Results: The level of pro-inflammatory parameters in serum was significantly higher in PCOS-affected women. The ratio [(sum of pro-inflammatory molecules) / (sum of SPMs plus hydroxylated intermediates)] reflecting the inflammatory state was significantly lower in the group of healthy women. Conclusion: There is a strong pro-inflammatory state in PCOS patients. Further research will clarify whether supplementation with SPMs or their precursors may improve this state.

The recently elucidated proresolving conjugates in tissue regeneration (CTR) maresin-CTR (MCTR), protectin-CTR (PCTR), and resolvin-CTR (RCTR), termed cysteinyl-specialized proresolving mediators (cys-SPMs) each promotes regeneration, controls infection, and accelerates resolution of inflammation. Here, we sought evidence for cys-SPM activation of primordial pathways in planaria (Dugesia japonica) regeneration that might link resolution of inflammation and regeneration. On surgical resection, planaria regeneration was enhanced with MCTR3, PCTR3, or RCTR3 (10 nM), each used for RNA sequencing. The three cys-SPMs shared up-regulation of 175 known transcripts with fold-change > 1.25 and combined false discovery rate (FDR) < 0.002, and 199 canonical pathways (FDR < 0.25), including NF-κB pathways and an ortholog of human TRAF3 (TNFR-associated factor 3). Three separate pathway analyses converged on TRAF3 up-regulation by cys-SPMs. With human macrophages, three cys-SPMs each dose-dependently increased TRAF3 expression in a cAMP-PKA–dependent manner. TRAF3 overexpression in macrophages enhanced Interleukin-10 (IL-10) and phagocytosis of Escherichia coli. IL-10 also increased phagocytosis in a dose-dependent manner. Silencing of mouse TRAF3 in vivo significantly reduced IL-10 and macrophage phagocytosis. TRAF3 silencing in vivo also relieved cys-SPMs’ actions in limiting polymorphonuclear neutrophil in E. coli exudates. These results identify cys-SPM–regulated pathways in planaria regeneration, uncovering a role for TRAF3/IL-10 in regulating mammalian phagocyte functions in resolution. Cys-SPM activation of TRAF3 signaling is a molecular component of both regeneration and resolution of infectious inflammation.

A successful acute inflammatory response results in the elimination of infectious agents by neutrophils and monocytes, followed by resolution and repair through tissue-resident and recruited macrophages. Resolvins (D-series and E-series) are pro-resolving lipid mediators involved in resolution and tissue repair, who’s intracellular signaling remains of interest. Here, we report that D-series resolvins (RvD1- RvD5) activate phospholipase D (PLD), a ubiquitously expressed membrane lipase enzyme activity in modulating phagocyte functions. The mechanism for PLD-mediated actions of Resolvin-D5 (RvD5) in polarizing macrophages (M1-like towards M2-like) was found to be two-pronged: (a) RvD5 inhibits post-transcriptional modifications, by miRs and 3’exonucleases that process PLD2 mRNA, thus increasing PLD2 expression and activity; and (b) RvD5 enhances PLD2-S6Kinase signaling required for membrane expansion and efferocytosis. In an in vivo model of second organ reflow injury, we found that RvD5 did not reduce lung neutrophil myeloperoxidase levels in PLD2(−/−) mice compared to WT and PLD1(−/−) mice, confirming a novel role of PLD2 as the isoform in RvD5-mediated resolution processes. These results demonstrate that RvD5-PLD2 are attractive targets for therapeutic interventions in vascular inflammation such as ischemia-reperfusion injury and cardiovascular diseases.

Resolvin conjugates in tissue regeneration (RCTRs) are new chemical signals that accelerate resolution of inflammation, infection, and tissue regeneration. Herein, using liquid chromatography–tandem mass spectrometry–based metabololipidomics, we identified RCTRs in human spleen, lymph node, bone marrow, and brain. In human spleen incubated with Staphylococcus aureus , endogenous RCTRs were increased along with conversion of deuterium-labeled docosahexaenoic acid, conferring pathway activation. Physical and biological properties of endogenous RCTRs were matched with those prepared by total organic synthesis. The complete stereochemical assignment of bioactive RCTR1 is 8 R -glutathionyl-7 S ,17 S -dihydroxy-4 Z ,9 E ,11 E ,13 Z ,15 E ,19 Z -docosahexaenoic acid, RCTR2 is 8 R -cysteinylglycinyl-7 S ,17 S -dihydroxy-4 Z ,9 E ,11 E ,13 Z ,15 E ,19 Z -docosahexaenoic acid, and RCTR3 is 8 R -cysteinyl-7 S ,17 S -dihydroxy-4 Z ,9 E ,11 E ,13 Z ,15 E ,19 Z -docosahexaenoic acid. These stereochemically defined RCTRs stimulated human macrophage phagocytosis, efferocytosis, and planaria tissue generation. Proteome profiling demonstrated that RCTRs regulated both proinflammatory and anti-inflammatory cytokines with human macrophages. In microfluidic chambers, the three RCTRs limited human polymorphonuclear cell migration. In hind-limb ischemia-reperfusion–initiated organ injury, both RCTR2 and RCTR3 reduced polymorphonuclear cell infiltration into lungs. In infectious peritonitis, RCTR1 shortened the resolution intervals. Each RCTR (1 nmol/L) accelerated planaria tissue regeneration by approximately 0.5 days, with direct comparison to both maresin and protectin CTRs. Together, these results identify a new bioactive RCTR (ie, RCTR3) in human tissues and establish the complete stereochemistry and rank-order potencies of three RCTRs in vivo . Moreover, RCTR1, RCTR2, and RCTR3 each exert potent anti-inflammatory and proresolving actions with human leukocytes.

Local production and downstream metabolism of specialized proresolving lipid mediators (SPMs) are pivotal in regulating their biological actions during resolution of inflammation. Resolvin D4 (RvD4: 4S,5R,17S-trihydroxydocosa-6E,8E,10Z,13Z,15E,19Z hexaenoic acid) is one of the more recently elucidated SPMs with complete stereochemistry biosynthesized from docosahexaenoic acid. Here, we report a new multimilligram commercial synthesis that afforded enough material for matching, validation, and further evaluation of RvD4 functions. Using LC-MS-MS profiling, RvD4 was identified at bioactive amounts in human (1 pg/mL) and mouse bone marrow (12 pg/femur and tibia). In mouse bone marrow, ischemia increased the formation of RvD4 > 37-fold (455 pg/femur and tibia). Two separate mouse ischemic injury models were used, where RvD4 reduced second organ reperfusion lung injury > 50%, demonstrating organ protection. Structure–function relationships of RvD4 demonstrated > 40% increase in neutrophil and monocyte phagocytic function in human whole blood in comparison with 2 separate trans-containing double bond isomers that were inactive. These 2 isomers were prepared by organic synthesis: 4S,5R,17S-trihydroxydocosa-6E,8E,10E,13Z,15E,19Z-hexaenoic acid (10-trans-RvD4), a natural isomer, and 4S,5R,17S-trihydroxydocosa-6E,8E,10E,13E,15E,19Z-hexaenoic acid (10,13-trans-RvD4), a rogue isomer. Compared to leukotriene B4, D-series resolvins (RvD1, RvD2, RvD3, RvD4, or RvD5) did not stimulate human neutrophil chemotaxis monitored via real-time microfluidics chambers. A novel 17-oxo-containing-RvD4 product of eicosanoid oxidoreductase was identified with human bone marrow cells. Comparison of 17-oxo-RvD4 to RvD4 demonstrated that with human leukocytes 17-oxo-RvD4 was inactive. Together, these provide commercial-scale synthesis that permitted a second independent validation of RvD4 complete stereochemical structure as well as evidence for RvD4 regulation in tissues and its stereoselective phagocyte responses.

Resolution of acute inflammation is an active process governed by specialized proresolving mediators, including resolvin (Rv)D2, that activates a cell surface G protein–coupled receptor, GPR18/DRV2. In this study, we investigated RvD2-DRV2–dependent resolution mechanisms using DRV2-deficient mice (DRV2-knockout [KO]). In polymicrobial sepsis initiated by cecal ligation and puncture, RvD2 (∼2.7 nmol/mouse) significantly increased survival (>50%) of wild-type mice and reduced hypothermia and bacterial titers compared with vehicle-treated cecal ligation and puncture mice that succumbed at 48 h. Protection by RvD2 was abolished in DRV2-KO mice. Mass spectrometry–based lipid mediator metabololipidomics demonstrated that DRV2-KO infectious exudates gave higher proinflammatory leukotriene B4 and procoagulating thromboxane B2, as well as lower specialized proresolving mediators, including RvD1 and RvD3, compared with wild-type. RvD2-DRV2–initiated intracellular signals were investigated using mass cytometry (cytometry by time-of-flight), which demonstrated that RvD2 enhanced phosphorylation of CREB, ERK1/2, and STAT3 in WT but not DRV2-KO macrophages. Monitored by real-time imaging, RvD2–DRV2 interaction significantly enhanced phagocytosis of live Escherichia coli, an action dependent on protein kinase A and STAT3 in macrophages. Taken together, we identified an RvD2/DRV2 axis that activates intracellular signaling pathways that increase phagocytosis-mediated bacterial clearance, survival, and organ protection. Moreover, these results provide evidence for RvD2-DRV2 and their downstream pathways in pathophysiology of infectious inflammation.

A successful acute inflammatory response results in the elimination of infectious agents by neutrophils and monocytes, followed by resolution and repair by tissue-resident and recruited macrophages. D-series resolvins are pro-resolving mediators involved in resolution and tissue repair, their intracellular signaling mechanism(s) are of interest. Here, we report that D-series resolvins activate phospholipase D (PLD), a ubiquitously expressed membrane lipase in modulating phagocyte functions. The mechanism for PLD-mediated actions of RvD5 in polarizing macrophages (M1-M2) was found to be two-pronged: (a) RvD5 inhibits post-transcriptional modifications, by miRs and 3’exonulceases that process PLD2 mRNA, thus increasing PLD2 expression and activity; (b) RvD5 enhances PLD2-S6K signaling and Actin expression required for membrane expansion and efferocytosis. In addition, investigating RvD5’s actions in second organ reflow injury, we found that RvD5 did not reduce lung neutrophil myeloperoxidase levels in PLD2-/- mice compared to WT and PLD1-/- mice, pointing to a unique role of PLD2 as the relevant isoform in RvD5-mediated resolution. These results demonstrate that RvD5-PLD2 are attractive targets for therapeutic interventions in vascular inflammation such as I/R injury and cardiovascular diseases.

RATIONALE: CD69 is an immunomodulatory molecule induced during lymphocyte activation. Following stroke, T-lymphocytes upregulate CD69 but its function is unknown. OBJECTIVE: We investigated whether CD69 was involved in brain damage following an ischemic stroke. METHODS AND RESULTS: We used adult male mice on the C57BL/6 or BALB/c backgrounds, including wild-type mice and CD69-/- mice, and CD69+/+ and CD69-/- lymphocyte-deficient Rag2-/- mice, and generated chimeric mice. We induced ischemia by transient or permanent middle cerebral artery occlusion. We measured infarct volume, assessed neurological function, and studied CD69 expression, as well as platelet function, fibrin(ogen) deposition, and VWF (von Willebrand factor) expression in brain vessels and VWF content and activity in plasma, and performed the tail-vein bleeding test and the carotid artery ferric chloride-induced thrombosis model. We also performed primary glial cell cultures and sorted brain CD45-CD11b-CD31+ endothelial cells for mRNA expression studies. We blocked VWF by intravenous administration of anti-VWF antibodies. CD69-/- mice showed larger infarct volumes and worse neurological deficits than the wild-type mice after ischemia. This worsening effect was not attributable to lymphocytes or other hematopoietic cells. CD69 deficiency lowered the time to thrombosis in the carotid artery despite platelet function not being affected. Ischemia upregulated Cd69 mRNA expression in brain endothelial cells. CD69-deficiency increased fibrin(ogen) accumulation in the ischemic tissue, and plasma VWF content and activity, and VWF expression in brain vessels. Blocking VWF reduced infarct volume and reverted the detrimental effect of CD69-/- deficiency. CONCLUSIONS: CD69 deficiency promotes a prothrombotic phenotype characterized by increased VWF and worse brain damage after ischemic stroke. The results suggest that CD69 acts as a downregulator of endothelial activation., The study was funded by the Spanish Ministerio de Economía y Competitividad (MINECO; grant SAF2014-56279-R and SAF2017-87459-R to A.M. Planas), Acción Estratégica de Salud (grants AES 1366/13 and AESI 1346/16 to P. Lauzurica), and Fundació la Marató de TV3 (grants 474-082230 and 20153031 to P. Garcia-de-Frutos). F. Miró-Mur had a PERIS award by the Health Department of the Generalitat de Catalunya. A. Otxoa-de-Amezaga has an FPI fellowship (MINECO).

Deep vein thrombosis (DVT) is a common cardiovascular disease with a major effect on quality of life, and safe and effective therapeutic measures to efficiently reduce existent thrombus burden are scarce. Using a comprehensive targeted liquid chromatography-tandem mass spectrometry-based metabololipidomics approach, we established temporal clusters of endogenously biosynthesized specialized proresolving mediators (SPMs) and proinflammatory and prothrombotic lipid mediators during DVT progression in mice. Administration of resolvin D4 (RvD4), an SPM that was enriched at the natural onset of thrombus resolution, significantly reduced thrombus burden, with significantly less neutrophil infiltration and more proresolving monocytes in the thrombus, as well as an increased number of cells in an early apoptosis state. Moreover, RvD4 promoted the biosynthesis of other D-series resolvins involved in facilitating resolution of inflammation. Neutrophils from RvD4-treated mice were less susceptible to an ionomycin-induced release of neutrophil extracellular traps (NETs), a meshwork of decondensed chromatin lined with histones and neutrophil proteins critical for DVT development. These results suggest that delivery of SPMs, specifically RvD4, modulates the severity of thrombo-inflammatory disease in vivo and improves thrombus resolution.

Inflammatory resolution is a process that, when uncontrolled, impacts many organs and diseases. As an active, self-limited inflammatory process, resolution involves biosynthesis of specialized proresolving mediators (SPM) (e.g., lipoxins, resolvins [Rv], protectins, and maresins). Because vagal stimulation impacts inflammation, we examined human and mouse vagus ex vivo to determine if they produce lipid mediators. Using targeted lipid mediator metabololipidomics, we identified lipoxins, Rv, and protectins produced by both human and mouse vagus as well as PGs and leukotrienes. Human vagus produced SPM (e.g., RvE1, NPD1/PD1, MaR1, RvD5, and LXA4) on stimulation that differed from mouse (RvD3, RvD6, and RvE3), demonstrating species-selective SPM. Electrical vagus stimulation increased SPM in both human and mouse vagus as did incubations with Escherichia coli. Electrical vagus stimulation increased SPM and decreased PGs and leukotrienes. These results provide direct evidence for vagus SPM and eicosanoids. Moreover, they suggest that this vagus SPM circuit contributes to a new proresolving vagal reflex.

Proinflammatory eicosanoids (prostaglandins and leukotrienes) and specialized pro-resolving mediators (SPM) are temporally regulated during infections. Here we show that human macrophage phenotypes biosynthesize unique lipid mediator signatures when exposed to pathogenic bacteria. E. coli and S. aureus each stimulate predominantly proinflammatory 5-lipoxygenase (LOX) and cyclooxygenase pathways (i.e., leukotriene B4 and prostaglandin E2) in M1 macrophages. These pathogens stimulate M2 macrophages to produce SPMs including resolvin D2 (RvD2), RvD5, and maresin-1. E. coli activates M2 macrophages to translocate 5-LOX and 15-LOX-1 to different subcellular locales in a Ca2+-dependent manner. Neither attenuated nor non-pathogenic E. coli mobilize Ca2+ or activate LOXs, rather these bacteria stimulate prostaglandin production. RvD5 is more potent than leukotriene B4 at enhancing macrophage phagocytosis. These results indicate that M1 and M2 macrophages respond to pathogenic bacteria differently, producing either leukotrienes or resolvins that further distinguish inflammatory or pro-resolving phenotypes., M1 and M2 cells are representative of proinflammatory versus resolving macrophages, respectively. Here the authors characterize the lipid mediator response to bacterial infection by these cells and show that differing panels of leukotrienes and specialized pro-resolving mediators contribute to control of the dichotomy.

El pdf del artículo es la versión post-print.-- et al., Purpose: Stroke induces strong expression of the 72-kDa heat-shock protein (HSP-70) in the ischaemic brain, and neuronal expression of HSP-70 is associated with the ischaemic penumbra. The aim of this study was to image induction of Hsp-70 gene expression in vivo after brain ischaemia using reporter mice. Methods: A genomic DNA sequence of the Hspa1b promoter was used to generate an Hsp70-mPlum far-red fluorescence reporter vector. The construct was tested in cellular systems (NIH3T3 mouse fibroblast cell line) by transient transfection and examining mPlum and Hsp-70 induction under a challenge. After construct validation, mPlum transgenic mice were generated. Focal brain ischaemia was induced by transient intraluminal occlusion of the middle cerebral artery and the mice were imaged in vivo with fluorescence reflectance imaging (FRI) with an intact skull, and with confocal microscopy after opening a cranial window. Results: Cells transfected with the Hsp70-mPlum construct showed mPlum fluorescence after stimulation. One day after induction of ischaemia, reporter mice showed a FRI signal located in the HSP-70-positive zone within the ipsilateral hemisphere, as validated by immunohistochemistry. Live confocal microscopy allowed brain tissue to be visualized at the cellular level. mPlum fluorescence was observed in vivo in the ipsilateral cortex 1 day after induction of ischaemia in neurons, where it is compatible with penumbra and neuronal viability, and in blood vessels in the core of the infarction. Conclusion: This study showed in vivo induction of Hsp-70 gene expression in ischaemic brain using reporter mice. The fluorescence signal showed in vivo the induction of Hsp-70 in penumbra neurons and in the vasculature within the ischaemic core. © 2012 Springer-Verlag Berlin Heidelberg., Financed in part by the European Community (Diagnostic Molecular Imaging Project, DIMI, EC-FP6-project LSHB-CT-2005-512146 and FP7/2007-2013 HEALTH, grant agreement no. 201024-ARISE), and the Spanish Ministry of Economy (SAF2008-04515-CO2-01/02 and SAF2011-30492). X. de la Rosa has a FPI PhD Fellowship from the Spanish Ministry of Economy.

Oxidative and nitrosative stress are targets for intervention after ischemia/reperfusion. The aim of this study was to explore the effect of CR-6, a vitamin-E analogue that is antioxidant and scavenger of nitrogen-reactive species. Sprague–Dawley rats had the middle cerebral artery (MCA) occluded either for 90 mins or permanently. Cortical perfusion was continuously monitored by laser–Doppler flowmetry. CR-6 (100 mg/kg) was administered orally either at 2 and 8 h after MCA occlusion, or at 2 h only. Infarct volume, neurological deficit, and signs of reperfusion injury were evaluated. CR-6 was detected in plasma and brain by HPLC. CR-6 reduced glutathione consumption in the ischemic brain and superoxide generation in the isolated MCA. CR-6 decreased infarct volume and attenuated the neurological deficit at 1 and 7 days after ischemia/reperfusion, but not after permanent ischemia. Immediately after reperfusion, cortical blood flow values returned to their baseline (±20%) in several animals, whereas others showed hyper-perfusion (>20% of baseline). Reactive hyperemia was associated with adverse events such as increased cortical BBB leakage, edema, protein nitrotyrosination, COX-2 expression, and neutrophil accumulation; and with a poorer outcome, and CR-6 attenuated these effects. In conclusion, oral CR-6 administration after transient ischemia protects the brain from reperfusion injury., This study was supported by grants from the Ministerio de Educación y Ciencia (SAF2005-05793-CO1, SAF2008-04515-C01, SAF2007-60406, and SAF2008-00048) and the European Community through the European Network of Excellence DiMI (LSHB-CT-2005-512146) and the FP7/2007-2013 project (grant agreement no. 201024).

BACKGROUND AND PURPOSE-: Several lines of evidence support the involvement of mannose-binding lectin (MBL) in stroke brain damage. The lectin pathway of the complement system facilitates thrombin activation and clot formation under certain experimental conditions. In the present study, we examine whether MBL promotes thrombosis after ischemia/reperfusion and influences the course and prognosis of ischemic stroke. METHODS-: Middle cerebral artery occlusion/reperfusion was performed in MBL-deficient (n=85) and wild-type (WT; n=83) mice, and the brain lesion was assessed by MRI at days 1 and 7. Relative cerebral blood flow was monitored up to 6 hours after middle cerebral artery occlusion with laser speckle contrast imaging. Fibrin(ogen) was analyzed in the brain vasculature and plasma, and the effects of thrombin inhibitor argatroban were evaluated to assess the role of MBL in thrombin activation. RESULTS-: Infarct volumes and neurological deficits were smaller in MBL knockout mice than in WT mice. Relative cerebral blood flow values during middle cerebral artery occlusion and at reperfusion were similar in both groups, but decreased during the next 6 hours in the WT group only. Also, the WT mice showed more fibrin(ogen) in brain vessels and a better outcome after argatroban treatment. In contrast, argatroban did not improve the outcome in MBL knockout mice. CONCLUSIONS-: MBL promotes brain damage and functional impairment after brain ischemia/reperfusion in mice. These effects are secondary to intravascular thrombosis and impaired relative cerebral blood flow during reperfusion. Argatroban protects WT mice, but not MBL knockout mice, emphasizing a role of MBL in local thrombus formation in acute ischemia/reperfusion. © 2014 American Heart Association, Inc., Work supported by the Spanish Ministries of Health (PI10/01898 and PS09/00579) and Economy (SAF2011-30492) and Fundació Cellex Barcelona. X.d.l.R. had a PhD fellowship from the Spanish Ministry of Economy