Resolution Of Acute Inflammation Research Articles

Молекулярные и клеточные механизмы воспаления при подагре

В обзоре проанализированы механизмы подагрического воспаления и разрешения острого воспаления при подагре, и то, как их понимание способствует созданию новых технологий лечения подагры. В первой части обзора анализируется кристалл-индуцированное воспаление при подагре, которое связано с активацией инфламмасомы NLRP3 в макрофагах, состоящее из двух этапов: 1) синтез компонентов инфламмасомы; и 2) сборка инфламмасомы. Проанализированы сигналы, активирующие синтез компонентов инфламмасомы, которые генерируются при взаимодействии кристаллов урата мононатрия с макрофагами. Описаны этапы инициации воспаления при подагре: синтез компонентов инфламмасомы, про-каспаз и про-IL-1β. IL-1β - основной эффекторный цитокин, который запускает не только воспалительный ответ, но и вызывает вазодилатацию сосудов, привлечение нейтрофилов к месту отложения кристаллов и еще большее усиление острого воспалительного эпизода через TLR-зависимую активацию NF-κB (фактор транскрипции). Рассматривается роль растворимой мочевой кислоты в активации инфламмасомы NLRP3. Подчёркнуто, что в разрешении острого воспаления при подагре основную роль играют те же клетки, что и в развитии классической воспалительной реакции: макрофаги и нейтрофилы. В обзоре рассмотрены сигнальные пути, которые переключают воспалительный ответ на разрешение и завершение воспаления: AMPK- (AMP-активируемая киназа) зависимый путь; антивоспалительные цитокины TGFβ1, IL-10 и IL-1Ra; белок аннексин А1 (AnxA1) и α1-антитрипсин (ААТ). Описаны способы терапевтического блокирования воспаления при подагре с помощью ингибиторов инфламмасомы и ингибиторов IL-1β. Изучение механизмов подагрического воспаления и его разрешения привело к идее о разработке методов репрограммирования иммунных клеток и адаптивной иммунотерапии подагры, методов, которые при других заболеваниях, таких как рак, уже показали выдающиеся возможности лечения больных.The review analyzes mechanisms of gouty inflammation and resolution of acute inflammation in gout and shows how their understanding contributes to creation of new technologies for the treatment of gout. The first part of the review addresses crystal-induced inflammation in gout, which is associated with activation of the NLRP3 inflammasome in macrophages. The crystal-induced inflammation consists of two stages, 1) synthesis of inflammasome components and 2) inflammasome assembly. The review analyzes signals activating the synthesis of inflammasome components, which are generated by the interaction of MSU (monosodium urate crystals) and macrophages. Stages of inflammation initiation are described, including the synthesis of inflammasome components, pro-caspases and pro-IL-1β. IL-1β is the main effector cytokine of gouty inflammation, which not only triggers the inflammatory response but also induces vasodilation, attraction of neutrophils to the place of crystal deposition, and even a greater potentiation of the acute inflammatory episode via the TLR-dependent activation of NF-κB (transcription factor). The role of soluble uric acid in the activation of NLRP3 inflammasomes is addressed. The main role in resolving acute gouty inflammation belongs to the same cells, macrophages and neutrophils, that contribute to the development of inflammation. The review focuses on signaling pathways switching the inflammatory response to inflammation resolution and termination, including the AMPK (AMP-activated kinase) signaling pathway, the TGFβ1, IL-10 and IL-1Ra anti-inflammatory cytokines, the protein annexin A1 (AnxA1), and α1-antitrypsin (AAT). The authors described in detail the techniques for therapeutic suppression of inflammation in gout using inflammasome and IL-1β inhibitors. Studying the mechanisms of gouty inflammation and its resolution has resulted in development of methods for reprogramming immune cells and adaptive immunotherapy of gout. These methods have already shown outstanding therapeutic potential for patients with other diseases such as cancer.

Exercise Promotes Resolution of Acute Inflammation by Catecholamine-Mediated Stimulation of Resolvin D1 Biosynthesis.

The mechanisms by which regular exercise prevents the development and progression of chronic inflammatory diseases are largely unknown. We find that exercise enhances resolution of acute inflammation by augmenting resolvin D1 (RvD1) levels and by promoting macrophage phagocytosis. When compared with sedentary controls, mice that performed a four-week treadmill exercise regimen displayed higher macrophage phagocytic activity, enhanced RvD1 levels, and earlier neutrophil clearance following an acute inflammatory challenge. In acute inflammatory cell extracts from exercised mice, we found elevated expression of Alox15 and Alox5 and higher RvD1 levels. Because exercise stimulates release of epinephrine, which has immunomodulatory effects, we questioned whether epinephrine exerts proresolving actions on macrophages. Epinephrine-treated macrophages displayed higher RvD1 levels and 15-lipoxygenase-1 protein abundance, which were prevented by incubation with the α1 adrenergic receptor (α1-AR) antagonist prazosin. Likewise, stimulation of the α1-AR with phenylephrine enhanced macrophage phagocytosis and RvD1 production. During acute inflammation, prazosin abrogated exercise-enhanced neutrophil clearance, macrophage phagocytosis, and RvD1 biosynthesis. These results suggest that exercise-stimulated epinephrine enhances resolution of acute inflammation in an α1-AR-dependent manner. To our knowledge, our findings provide new mechanistic insights into the proresolving effects of exercise that could lead to the identification of novel pathways to stimulate resolution.

The Role of Maresins in Inflammatory Pain: Function of Macrophages in Wound Regeneration

Although acute inflammatory responses are host-protective and generally self-limited, unresolved and delayed resolution of acute inflammation can lead to further tissue damage and chronic inflammation. The mechanism of pain induction under inflammatory conditions has been studied extensively; however, the mechanism of pain resolution is not fully understood. The resolution of inflammation is a biosynthetically active process, involving specialized pro-resolving mediators (SPMs). In particular, maresins (MaRs) are synthesized from docosahexaenoic acid (DHA) by macrophages and have anti-inflammatory and pro-resolving capacities as well as tissue regenerating and pain-relieving properties. A new class of macrophage-derived molecules—MaR conjugates in tissue regeneration (MCTRs)—has been reported to regulate phagocytosis and the repair and regeneration of damaged tissue. Macrophages not only participate in the biosynthesis of SPMs, but also play an important role in phagocytosis. They exhibit different phenotypes categorized as proinflammatory M1-like phenotypes and anti-inflammatory M2 phenotypes that mediate both harmful and protective functions, respectively. However, the signaling mechanisms underlying macrophage functions and phenotypic changes have not yet been fully established. Recent studies report that MaRs help resolve inflammatory pain by enhancing macrophage phagocytosis and shifting cytokine release to the anti-inflammatory M2 phenotypes. Consequently, this review elucidated the characteristics of MaRs and macrophages, focusing on the potent action of MaRs to enhance the M2 macrophage phenotype profiles that possess the ability to alleviate inflammatory pain.

Assessment of Neutrophil Apoptosis.

The process of neutrophil apoptosis has an important role in the resolution of acute inflammation. Apoptotic cell death is characterized by a coordinated sequence of cellular alterations that serve to uncouple neutrophil effector functions whilst maintaining plasma membrane integrity. In this way the release on neutrophil intracellular contents, including proteases, glycosidases, and reactive oxygen species, is limited during apoptosis. In addition, plasma membrane alterations associated with neutrophil apoptosis provide molecular cues that enable recognition by phagocytic cells, including macrophages. The recognition and uptake of apoptotic neutrophils by macrophages dampens proinflammatory responses to pathogen- or damage-associated molecular patterns and triggers release of proresolution mediators, that further promote resolution of inflammation. The key cellular and molecular events that act to control neutrophil apoptosis and subsequent macrophage phagocytosis have been characterized by in vitro studies, unveiling potential therapeutic targets for the manipulation of these regulatory pathways. In this chapter, we outline some of the key assays that are used to assess neutrophil apoptosis in vitro, together with methods to assess activation of the apoptotic machinery and phagocytic clearance of apoptotic neutrophils.

Maresin 1 activates LGR6 receptor promoting phagocyte immunoresolvent functions.

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 3H-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.

In Vitro Anti-Inflammatory and Immunomodulatory Activities of an Extract from the Roots of Bupleurum rotundifolium

Background: Some Bupleurum species, such as the Bupleurum chinense DC. or the Bupleurum scorzonerifolium Willd have been extensively studied (especially their roots) for the treatment of inflammation. In contrast, only compounds extracted from the aerial parts of Bupleurum rotundifolium have been studied and showed anti-inflammatory or antiproliferative activities. This study was conducted to investigate the antioxidant, anti-inflammatory, and immunomodulatory effects of Bupleurum rotundifolium roots. Methods: To tackle the various aspects of inflammation, we studied in vitro a methanolic extract from the roots of Bupleurum rotundifolium on peripheral blood mononuclear cells (PBMCs), polymorphonuclear neutrophils (PMNs), and the monocytic cells THP-1. Its antioxidant capacities and iron-chelating activity were assessed. The extract was tested on THP-1 differentiation, reactive oxygen species (ROS) production by leukocytes, neutrophils chemotaxis, cytokines, PGE2 production, and NF-κB activation in PBMCs. Results: The extract showed a decreased ROS production in stimulated cells. It increased PBMC chemokine secretion and up-regulated the differentiation of THP-1 monocytes into macrophage-like cells, indicating a potential interest of the extract in the resolution of acute inflammation. In addition, the analysis of cytokine production suggests that Bupleurum rotundifolium has immunomodulatory properties. Conclusions: Cytokines secretion, especially IL-1β and IL-12p70, provided us with a set of indicators suggesting that the extract might be able to drive the polarization of macrophages and lymphocytes toward a Th2 anti-inflammatory profile in excessive inflammation.

ROCK Inhibition Drives Resolution of Acute Inflammation by Enhancing Neutrophil Apoptosis.

Uncontrolled inflammation leads to tissue damage and it is central for the development of chronic inflammatory diseases and autoimmunity. An acute inflammatory response is finely regulated by the action of anti-inflammatory and pro-resolutive mediators, culminating in the resolution of inflammation and restoration of homeostasis. There are few studies investigating intracellular signaling pathways associated with the resolution of inflammation. Here, we investigate the role of Rho-associated kinase (ROCK), a serine/threonine kinase, in a model of self-resolving neutrophilic inflammatory. We show that ROCK activity, evaluated by P-MYPT-1 kinetics, was higher during the peak of lipopolysaccharide-induced neutrophil influx in the pleural cavity of mice. ROCK inhibition by treatment with Y-27632 decreased the accumulation of neutrophils in the pleural cavity and was associated with an increase in apoptotic events and efferocytosis, as evaluated by an in vivo assay. In a model of gout, treatment with Y-27632 reduced neutrophil accumulation, IL-1β levels and hypernociception in the joint. These were associated with reduced MYPT and IκBα phosphorylation levels and increased apoptosis. Finally, inhibition of ROCK activity also induced apoptosis in human neutrophils and destabilized cytoskeleton, extending the observed effects to human cells. Taken together, these data show that inhibition of the ROCK pathway might represent a potential therapeutic target for neutrophilic inflammatory diseases.

Activation of Resolution Pathways to Prevent and Fight Chronic Inflammation: Lessons From Asthma and Inflammatory Bowel Disease.

Formerly considered as a passive process, the resolution of acute inflammation is now recognized as an active host response, with a cascade of coordinated cellular and molecular events that promotes termination of the inflammatory response and initiates tissue repair and healing. In a state of immune fitness, the resolution of inflammation is contained in time and space enabling the restoration of tissue homeostasis. There is increasing evidence that poor and/or inappropriate resolution of inflammation participates in the pathogenesis of chronic inflammatory diseases, extending in time the actions of pro-inflammatory mechanisms, and responsible in the long run for excessive tissue damage and pathology. In this review, we will focus on how resolution can be the target for therapy in “Th1/Th17 cell-driven” immune diseases and “Th2 cell-driven” immune diseases, with inflammatory bowel diseases (IBD) and asthma, as relevant examples. We describe the main cells and mediators stimulating the resolution of inflammation and discuss how pharmacological and dietary interventions but also life style factors, physical and psychological conditions, might influence the resolution phase. A better understanding of the impact of endogenous and exogenous factors on the resolution of inflammation might open a whole area in the development of personalized therapies in non-resolving chronic inflammatory diseases.

The evolution of healthy skin to acne lesions: a longitudinal, in vivo evaluation with reflectance confocal microscopy and optical coherence tomography.

Comedogenesis is defined as the process of the development of a new comedo, which is of great importance for the understanding of acne. To evaluate the formation and evolution of acne lesions from clinically unaffected skin of patients with mild-moderate acne to characterize the morphological changes and natural resolution by means of in vivo reflectance confocal microscopy (RCM) and dynamic optical coherence tomography (D-OCT). Ten patients with mild-moderate acne, not assuming any topical or systemic therapy, comprised between 12 and 30 years of age, were recruited. A target area of 4 × 4 mm of the face, without acne lesions at baseline, was selected. A set of standardized clinical pictures, RCM and D-OCT images were acquired weekly for 6 weeks and evaluated. Seventy full sets of clinical, RCM and D-OCT images were analysed. The appearance of acne lesion is preceded by an increase of large bright follicles in the area corresponding to infundibular keratinization, followed by increment of inflammation parameter, such as increased of small bright cells upon RCM and vascular network upon D-OCT, which return to normal after the resolution of acute inflammation. Acne skin dynamics is complex and seems characterized by the early increase in the number of dysmorphic pilosebaceous units and the hyperkeratinization of the acroinfundibulum of the pilosebaceous duct prior to the occurrence of inflammatory events around the follicle. The processes of hyperkeratinization and inflammatory phenomena may generate a pathologic vicious cycle, which characterizes acne through progressive worsening and a self-sustainment mechanism.

Neutrophils in the initiation and resolution of acute pulmonary inflammation: understanding biological function and therapeutic potential.

Acute respiratory distress syndrome (ARDS) is the often fatal sequelae of a broad range of precipitating conditions. Despite decades of intensive research and clinical trials there remain no therapies in routine clinical practice that target the dysregulated and overwhelming inflammatory response that characterises ARDS. Neutrophils play a central role in the initiation, propagation and resolution of this complex inflammatory environment by migrating into the lung and executing a variety of pro‐inflammatory functions. These include degranulation with liberation of bactericidal proteins, release of cytokines and reactive oxygen species as well as production of neutrophil extracellular traps. Although these functions are advantageous in clearing bacterial infection, the consequence of associated tissue damage, the contribution to worsening acute inflammation and prolonged neutrophil lifespan at sites of inflammation are deleterious. In this review, the importance of the neutrophil will be considered, together with discussion of recent advances in understanding neutrophil function and the factors that influence them throughout the phases of inflammation in ARDS. From a better understanding of neutrophils in this context, potential therapeutic targets are identified and discussed. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Abstract A148: A hydrogel platform for the delivery of specialized pro-resolving mediators to treat chronic inflammatory disease

Abstract The resolution of acute inflammation is an active process orchestrated by mediators that prevent further recruitment of inflammatory cells and promote clearance of microbes and dying cells. Chronic inflammation can arise when resolution is diminished due to a scarcity of these pro-resolving mediators. Current immunosuppressive drugs for the treatment of chronic inflammatory diseases such as IBD, arthritis, or psoriasis temporarily block inflammation without initiating resolution or tissue repair, leading to the recurrence of chronic inflammation. Additionally, systemic administration of these drugs leaves patients susceptible to tuberculosis, lymphoma, and opportunistic infections. Resolvins are a class of evolutionarily conserved lipid mediators that return tissue to homeostasis without immunosuppression by promoting phagocytosis of debris and microbes, and preventing proinflammatory cytokine production and cellular infiltration. To enhance dose sparing and stability, we have developed a tunable hydrogel platform to deliver resolvins to various sites of chronic inflammation. For oral delivery, this hydrogel is further encapsulated into a pH-sensitive microparticle formulated using anionic polymers, to target the large intestine. Using a mouse model of colitis, we demonstrate the ability of the hydrogel to resolve intestinal inflammation, initiate repair of the intestinal barrier, and regulate the gut microbiota. Our tunable hydrogel platform could have profound effects on the prevention of gastrointestinal cancers and chronic inflammatory disease. Citation Format: Padmini Sushila Pillai, Jamie Webster, Robert Langer. A hydrogel platform for the delivery of specialized pro-resolving mediators to treat chronic inflammatory disease [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A148.

Frontline Science: Monocytes sequentially rewire metabolism and bioenergetics during an acute inflammatory response.

Metabolism directs the severe acute inflammatory reaction of monocytes to guard homeostasis. This occurs by sequentially activating anabolic immune effector mechanisms, switching to immune deactivation mechanisms and then restoring immunometabolic homeostasis. Nuclear sirtuin 1 and mitochondrial pyruvate dehydrogenase kinase metabolically drive this dynamic and are druggable targets that promote immunometabolic resolution in septic mice and increase survival. We used unbiased metabolomics and a validated monocyte culture model of activation, deactivation, and partial resolution of acute inflammation to sequentially track metabolic rewiring. Increases in glycogenolysis, hexosamine, glycolysis, and pentose phosphate pathways were aligned with anabolic activation. Activation transitioned to combined lipid, protein, amino acid, and nucleotide catabolism during deactivation, and partially subsided during early resolution. Lipid metabolic rewiring signatures aligned with deactivation included elevated n-3 and n-6 polyunsaturated fatty acids and increased levels of fatty acid acylcarnitines. Increased methionine to homocysteine cycling increased levels of s-adenosylmethionine rate-limiting transmethylation mediator, and homocysteine and cysteine transsulfuration preceded increases in glutathione. Increased tryptophan catabolism led to elevated kynurenine and de novo biosynthesis of nicotinamide adenine dinucleotide from quinolinic acid. Increased branched-chain amino acid catabolism paralleled increases in succinyl-CoA. A rise in the Krebs cycle cis-aconitate-derived itaconate and succinate with decreased fumarate and acetyl-CoA levels occurred concomitant with deactivation and subsided during early resolution. The data suggest that rewiring of metabolic and mitochondrial bioenergetics by monocytes sequentially activates, deactivates, and resolves acute inflammation.

Отражение современных концепций патогенеза экссудативного среднего отита у детей в клинической практике

The scientific work presents the data of observation of 52 patients with combined lymphoepithelial pharyngeal ring pathology and exudative otitis media (EOM), admitted for routine surgical treatment. The study results indicate, that the pathology of the lymphoepithelial pharyngeal ring was accompanied by a significant Eustachian tube dysfunction with the development of catarrhal and serous stages of secretory otitis media in 90.38% (47 patients) and mucoid stage (the «glue ear») in 9.62% (5 children) who needed tympanostomy tube. The authors have considered the key problems of etiopathogenesis of suppurative otitis media in children based on the analysis of their own clinical experience and the present-day clinical experimental works, reputable monographs. According to some authors, some cases of tympanic cavity exudate are supposedly the result of incomplete resolution of previous acute purulent inflammation. It is indirectly indicated by the data of inoculation of material for detection of bacterial flora and identification of cellular composition (the signs of infectious etiology). The results prove, that the viral and bacterial infections play an important role in the pathogenesis of EOM. The use of antibacterial therapy in some cases will probably result in a sluggish inflammatory process and the preservation of exudation in the tympanic cavity. However, in 46.2% cases, the patients diagnosed with the exudative otitis media had no acute otitis media in anamnesis. The aseptic nature of ear secret was revealed by bacteriological method in 88.5% cases, but the data of cytological analysis in 57.7% cases indirectly indicate the previous inflammation of infectious etiology. The allergic anamnesis in 73% (38 people), in particular, allergic rhinitis in 36.5% (19 people), could also accelerate and/or trigger the development of EOM.

Innate Immune Cell Suppression and the Link With Secondary Lung Bacterial Pneumonia.

Secondary infections arise as a consequence of previous or concurrent conditions and occur in the community or in the hospital setting. The events allowing secondary infections to gain a foothold have been studied for many years and include poor nutrition, anxiety, mental health issues, underlying chronic diseases, resolution of acute inflammation, primary immune deficiencies, and immune suppression by infection or medication. Children, the elderly and the ill are particularly susceptible. This review is concerned with secondary bacterial infections of the lung that occur following viral infection. Using influenza virus infection as an example, with comparisons to rhinovirus and respiratory syncytial virus infection, we will update and review defective bacterial innate immunity and also highlight areas for potential new investigation. It is currently estimated that one in 16 National Health Service (NHS) hospital patients develop an infection, the most common being pneumonia, lower respiratory tract infections, urinary tract infections and infection of surgical sites. The continued drive to understand the mechanisms of why secondary infections arise is therefore of key importance.

Identification of Chemotype Agonists for Human Resolvin D1 Receptor DRV1 with Pro-Resolving Functions

Resolution of acute inflammation is governed, inpart, by specialized pro-resolving mediators, including lipoxins, resolvins, protectins, and maresins. Among them, resolvin D1 (RvD1) exhibits potent pro-resolving functions via activating human resolvin D1 receptor (DRV1/GPR32). RvD1 is a complex molecule that requires challenging organic synthesis, diminishing its potential as a therapeutic. Therefore, we implemented a high-throughput screening of small-molecule libraries and identified several chemotypes that activated recombinant DRV1, represented by NCGC00120943 (C1A), NCGC00135472 (C2A), pMPPF, and pMPPI. These chemotypes alsoelicited rapid impedance changes in cells overexpressing recombinant DRV1. With human macrophages,they each stimulated phagocytosis of serum-treated zymosan at concentrations comparable with that of RvD1, the endogenous DRV1 ligand. In addition, macrophage phagocytosis of live E.coli was significantly increased by these chemotypes inDRV1-transfected macrophages, compared with mock-transfected cells. Taken together, these chemotypes identified by unbiased screens act as RvD1 mimetics, exhibiting pro-resolving functions via interacting with human DRV1.

Identification of specialized pro-resolving mediator clusters from healthy adults after intravenous low-dose endotoxin and omega-3 supplementation: a methodological validation

Specialized pro-resolving mediator(s) (SPMs) are produced from the endogenous ω-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and accelerate resolution of acute inflammation. We identified specific clusters of SPM in human plasma and serum using LC-MS/MS based lipid mediator (LM) metabololipidomics in two separate laboratories for inter-laboratory validation. The human plasma cluster consisted of resolvin (Rv)E1, RvD1, lipoxin (LX)B4, 18-HEPE, and 17-HDHA, and the human serum cluster consisted of RvE1, RvD1, AT-LXA4, 18-HEPE, and 17-HDHA. Human plasma and serum SPM clusters were increased after ω-3 supplementation (triglyceride dietary supplements or prescription ethyl esters) and low dose intravenous lipopolysaccharide (LPS) challenge. These results were corroborated by parallel determinations with the same coded samples in a second, separate laboratory using essentially identical metabololipidomic operational parameters. In these healthy subjects, two ω-3 supplementation protocols (Study A and Study B) temporally increased the SPM cluster throughout the endotoxin-challenge time course. Study A and Study B were randomized and Study B also had a crossover design with placebo and endotoxin challenge. Endotoxin challenge temporally regulated lipid mediator production in human serum, where pro-inflammatory eicosanoid (prostaglandins and thromboxane) concentrations peaked by 8 hours post-endotoxin and SPMs such as resolvins and lipoxins initially decreased by 2 h and were then elevated at 24 hours. In healthy adults given ω-3 supplementation, the plasma concentration of the SPM cluster (RvE1, RvD1, LXB4, 18-HEPE, and 17-HDHA) peaked at two hours post endotoxin challenge. These results from two separate laboratories with the same samples provide evidence for temporal production of specific pro-resolving mediators with ω-3 supplementation that together support the role of SPM in vivo in inflammation-resolution in humans.

Factors Produced by Macrophages Eliminating Apoptotic Cells Demonstrate Pro-Resolutive Properties and Terminate Ongoing Inflammation.

Unresolved inflammation is a common feature in the pathogenesis of chronic inflammatory/autoimmune diseases. The factors produced by macrophages eliminating apoptotic cells during resolution are crucial to terminate inflammation, and for subsequent tissue healing. We demonstrated here that the factors produced by macrophages eliminating apoptotic cells were sufficient to reboot the resolution of inflammation in vivo, and thus definitively terminated ongoing chronic inflammation. These factors were called SuperMApo and revealed pro-resolutive properties and accelerated acute inflammation resolution, as attested by both increased phagocytic capacities of macrophages and enhanced thioglycollate-induced peritonitis resolution. Activated antigen-presenting cells exposed to SuperMApo accelerated their return to homeostasis and demonstrated pro-regulatory T cell properties. In mice with ongoing collagen-induced arthritis, SuperMApo injection resolved and definitively terminated chronic inflammation. The same pro-resolving properties were observed in human settings in addition to xenogeneic colitis and graft-vs.-host disease modulation, highlighting SuperMApo as a new therapeutic opportunity to circumvent inflammatory diseases.

Abstract 16720: Exercise-Stimulated Catecholamine Release Enhances Resolution of Acute Inflammation

The mechanisms by which regular exercise prevents the development and progression of chronic inflammatory diseases are largely unknown. We find that exercise (Exe) enhances resolution of acute inflammation by promoting macrophage (MФ) phagocytosis and by augmenting resolvin D1 (RvD1) levels. When compared with sedentary controls (Sed), mice adapted to a 4-week treadmill exercise regimen displayed 1.48-fold higher MФ phagocytotic activity, enhanced RvD1 levels (Sed 28.08±1.5 vs Exe 48.01±8.6 pg/mL, n=6), and earlier neutrophilic clearance (ΔR i ~7 h) during peritonitis. Peritonitis cell extracts from exercise-adapted mice showed elevated expression of Alox15 (48 h: Sed 0.97±0.15 vs Exe 1.5±0.16 relative expression, n=8-9), Alox5 (48 h: Sed 0.77±0.15 vs Exe 1.7±0.27 relative expression, n=4-5), and RvD1 levels (48 h: 29.0±2.1 vs 52.6±8.9 pg/mL, n=5). Because exercise stimulates epinephrine (Epi) release, which has immunomodulatory effects, we questioned if Epi exerts pro-resolving actions on macrophages. Epi-treated macrophages displayed higher 15-lipoxygenase 1 expression and RvD1 levels, which were prevented by incubation with the α1 adrenergic receptor (AR-α1) blocker, Prazosin (Praz). During zymosan-induced peritonitis, Praz abrogated exercise-enhanced neutrophilic clearance (48 h: Exe+Veh 2.07±0.41 vs Exe+Praz 5.2±1.04 x10 6 PMN, n=5), MФ phagocytosis (Exe+Veh 33463.0±2174.0 vs Exe+Praz 8303.0±2748.0 MFI, n=5-7), and RvD1 biosynthesis (Exe+Veh 211.0±55.4 vs Exe+Praz 81.79±11.8 pg/mL, n=6). These results suggest that exercise-stimulated Epi release enhances resolution of acute inflammation in an AR-α1 dependent manner. These findings provide new mechanistic insights into the pro-resolving effects of exercise and may lead to the identification of novel pathways to stimulate resolution biology.

Regnase-1 controls colon epithelial regeneration via regulation of mTOR and purine metabolism

Damage to intestinal epithelial cell (IEC) layers during intestinal inflammation is associated with inflammatory bowel disease. Here we show that the endoribonuclease Regnase-1 controls colon epithelial regeneration by regulating protein kinase mTOR (the mechanistic target of rapamycin kinase) and purine metabolism. During dextran sulfate sodium-induced intestinal epithelial injury and acute colitis, Regnase-1∆IEC mice, which lack Regnase-1 specifically in the intestinal epithelium, were resistant to body weight loss, maintained an intact intestinal barrier, and showed increased cell proliferation and decreased epithelial apoptosis. Chronic colitis and tumor progression were also attenuated in Regnase-1∆IEC mice. Regnase-1 predominantly regulates mTORC1 signaling. Metabolic analysis revealed that Regnase-1 participates in purine metabolism and energy metabolism during inflammation. Furthermore, increased expression of ectonucleotidases contributed to the resolution of acute inflammation in Regnase-1∆IEC mice. These findings provide evidence that Regnase-1 deficiency has beneficial effects on the prevention and/or blocking of intestinal inflammatory disorders.

The deficiency of macrophage erythropoietin signaling contributes to delayed acute inflammation resolution in diet-induced obese mice

Obesity has been linked with altered acute inflammation resolution which contributes to obesity-related clinical complications; however, the mechanisms that contribute to obesity-related unresolved inflammation are not fully known. Here we demonstrated that the deficiency of macrophage erythropoietin (EPO) signaling contributed to delayed acute inflammation resolution in diet-induced obese mice. In zymosan-induced acute peritonitis, in line with the delayed resolution of inflammation, the induction of macrophage EPO signaling was significantly reduced in obese mice relative to normal mice. Exogenous EPO induced macrophage EPO signaling and promoted acute inflammation resolution in obese mice. Efferocytosis of apoptotic cells by macrophages which is central in inflammation resolution was impaired in obese mice and restored by exogenous EPO. Mechanistically, macrophage peroxisome proliferator-activated receptor-γ (PPARγ) was greatly reduced in obese mice and EPO increased macrophage PPARγ to promote efferocytosis in obese mice. Together, our results identify an important mechanism underlying aberrant acute inflammation resolution in obesity, with important implications for regulating unresolved acute inflammation and normalizing macrophage defects in obese and diabetic individuals.