Resolution of inflammation: targeting GPCRs that interact with lipids and peptides

Effect of non-surgical periodontal treatment on visfatin and chemerin concentration in the gingival crevicular fluid

Visfatin, as a novel adipokine, is considered to play a role in periodontal inflammation. Chemerin is another newly identified adipokine that is possible to have a role in periodontitis firstly reported in our previous study. The aim of the current study is to evaluate the gingival crevicular fluid (GCF) levels of visfatin and chemerin in periodontitis and and compare these adipokine levels with before and after non-surgical periodontal treatment. Twenty-nine patients with Stage III Grade B periodontitis and eighteen healthy subjects included in this cross-sectional cohort study. Clinical periodontal parameters and GCF were obtained from all subjects. Eight weeks after the following non-surgical periodontal treatment including scaling and root planning, samples and clinical periodontal parameters were collected again in the periodontitis group. The levels of adipokines were analyzed with standard enzyme-linked immunosorbent assay. The levels of visfatin and chemerin were statistically significantly higher at periodontitis group as compared to healthy group (P < 0.001). Although, no changes were observed in visfatin levels after periodontal treatment (P > 0.05), chemerin levels were significantly decreased (P < 0.001). Also, no differences were observed as compared to the healthy group (P > 0.05). Visfatin and chemerin may play a role in the periodontal disease process. In addition, it can be considered that the decreased chemerin levels after non-surgical periodontal treatment may play an important role for developing host modulation strategies.

Unlocking the power of NOX2: A comprehensive review on its role in immune regulation

Reactive oxygen species (ROS) are a family of highly reactive molecules with numerous, often pleiotropic functions within the cell and the organism. Due to their potential to destroy biological structures such as membranes, enzymes and organelles, ROS have long been recognized as harmful yet unavoidable by-products of cellular metabolism leading to "oxidative stress" unless counterbalanced by cellular anti-oxidative defense mechanisms. Phagocytes utilize this destructive potential of ROS released in high amounts to defend against invading pathogens. In contrast, a regulated and fine-tuned release of "signaling ROS" (sROS) provides essential intracellular second messengers to modulate central aspects of immunity, including antigen presentation, activation of antigen presenting cells (APC) as well as the APC:T cell interaction during T cell activation. This regulated release of sROS is foremost attributed to the specialized enzyme NADPH-oxidase (NOX) 2 expressed mainly in myeloid cells such as neutrophils, macrophages and dendritic cells (DC). NOX-2-derived sROS are primarily involved in immune regulation and mediate protection against autoimmunity as well as maintenance of self-tolerance. Consequently, deficiencies in NOX2 not only result in primary immune-deficiencies such as Chronic Granulomatous Disease (CGD) but also lead to auto-inflammatory diseases and autoimmunity. A comprehensive understanding of NOX2 activation and regulation will be key for successful pharmaceutical interventions of such ROS-related diseases in the future. In this review, we summarize recent progress regarding immune regulation by NOX2-derived ROS and the consequences of its deregulation on the development of immune disorders.

Plasma Chemerin Is Induced in Critically Ill Patients with Gram-Positive Infections

Chemerin is a chemoattractant protein abundantly expressed in hepatocytes. Chemerin exerts pro- and anti-inflammatory effects and acts as a pro-resolving protein. Chemerin levels are low in patients with liver cirrhosis and are increased in sepsis. The aim of this study was to identify associations between plasma chemerin levels and underlying diseases as well as causes of severe illness. The cohort included 32 patients with liver cirrhosis who had low systemic chemerin, and who were not considered for further evaluation. Plasma chemerin levels were similar between the 27 patients with systemic inflammatory response syndrome (SIRS), the 34 patients with sepsis and the 63 patients with septic shock. Chemerin in plasma correlated with C-reactive protein and leukocyte count but not with procalcitonin, a clinical marker of bacterial infection. Plasma chemerin did not differ among patients with and without ventilation and patients with and without dialysis. Vasopressor therapy was not associated with altered plasma chemerin levels. Infection with severe acute respiratory syndrome coronavirus 2 had no effect on plasma chemerin levels. Baseline levels of plasma chemerin could not discriminate between survivors and non-survivors. Notably, Gram-positive infection was associated with higher chemerin levels. In summary, the current study suggests that plasma chemerin might serve as an early biomarker for the diagnosis of Gram-positive infections in patients with sepsis.

Formyl Peptide Receptor Type 2 Deficiency in Myeloid Cells Amplifies Sepsis-Induced Cardiac Dysfunction

Using a global formyl peptide receptor (Fpr) 2 knockout mouse colony, we have reported the modulatory properties of this pro-resolving receptor in polymicrobial sepsis. Herein, we have used a humanized FPR2 (hFPR2) mouse colony, bearing an intact or a selective receptor deficiency in myeloid cells to dwell on the cellular mechanisms. hFPR2 mice and myeloid cell-specific hFPR2 KO (KO) mice were subjected to cecal ligation and puncture (CLP)-induced polymicrobial sepsis. Compared with hFPR2 mice, CLP caused exacerbated cardiac dysfunction (assessed by echocardiography), worsened clinical outcome, and impaired bacterial clearance in KO mice. This pathological scenario was paralleled by increased recruitment of pro-inflammatory monocytes and reduced M2-like macrophages within the KO hearts. In peritoneal exudates of KO mice, we quantified increased neutrophil and MHC II+ macrophage numbers but decreased monocyte/macrophage and MHC II- macrophage recruitment. hFPR2 upregulation was absent in myeloid cells, and local production of lipoxin A4 was reduced in septic KO mice. Administration of the FPR2 agonist annexin A1 (AnxA1) improved cardiac function in hFPR2 septic mice but had limited beneficial effects in KO mice, in which the FPR2 ligand failed to polarize macrophages toward an MHC II- phenotype. In conclusion, FPR2 deficiency in myeloid cells exacerbates cardiac dysfunction and worsens clinical outcome in polymicrobial sepsis. The improvement of cardiac function and the host immune response by AnxA1 is more effective in hFPR2-competent septic mice.

Inflammation-Controlled Anti-Inflammatory Hydrogels

While autoregulative adaptation is a common feature of living tissues, only a few feedback-controlled adaptive biomaterials are available so far. This paper herein reports a new polymer hydrogel platform designed to release anti-inflammatory molecules in response to the inflammatory activation of human blood. In this system, anti-inflammatory peptide drugs, targeting either the complement cascade, a complement receptor, or cyclophilin A, are conjugated to the hydrogel by a peptide sequence that is cleaved by elastase released from activated granulocytes. As a proof of concept, the adaptive drug delivery from the gel triggered by activated granulocytes and the effect of the released drug on the respective inflammatory pathways are demonstrated. Adjusting the gel functionalization degree is shown to allow for tuning the drug release profiles to effective doses within a micromolar range. Feedback-controlled delivery of covalently conjugated drugs from a hydrogel matrix is concluded to provide valuable safety features suitable to equip medical devices with highly active anti-inflammatory agents without suppressing the general immunosurveillance.

Urinary chemerin as a potential biomarker for inflammatory bowel disease

Purpose

Systemic levels of the adipokine chemerin are elevated in different inflammatory conditions such as inflammatory bowel disease (IBD). In IBD, chemerin protein expression in colon mucosa is induced and serum chemerin levels are increased. Aim of this study was to identify chemerin protein in human feces and/or urine and to evaluate a possible association with IBD activity.

Materials and methods

Feces and urine of 40 patients with IBD and the respective sera of 34 patients were collected. Chemerin levels were analyzed by immunoblot in feces and urine samples. In addition, enzyme-linked immunosorbent assay (ELISA) was used to measure chemerin in all urine, feces and serum samples of the patients and in urine of 17 healthy controls.

Results

Chemerin was not detectable in 80% of the human feces samples by ELISA. Chemerin in human urine was detected by immunoblot and ELISA. Compared to serum levels, urinary concentration was about 6,000-fold lower. Urinary chemerin did not differ between patients with ulcerative colitis (n = 15) and Crohn's disease (n = 25). Urinary chemerin was not related to its serum levels, did not correlate with serum C-reactive protein level and negatively correlated with serum creatinine. Of note, urinary chemerin of patients with a fecal calprotectin > 500 μg/g was significantly higher compared to patients with lower calprotectin levels and compared to healthy controls. Serum creatinine did not differ between the patient groups.

Conclusion

Urinary chemerin might present a novel non-invasive biomarker for monitoring IBD severity and clinical course.

Role of macrophages during skeletal muscle regeneration and hypertrophy-Implications for immunomodulatory strategies

Skeletal muscle is a plastic tissue that regenerates ad integrum after injury and adapts to raise mechanical loading/contractile activity by increasing its mass and/or myofiber size, a phenomenon commonly refers to as skeletal muscle hypertrophy. Both muscle regeneration and hypertrophy rely on the interactions between muscle stem cells and their neighborhood, which include inflammatory cells, and particularly macrophages. This review first summarizes the role of macrophages in muscle regeneration in various animal models of injury and in response to exercise-induced muscle damage in humans. Then, the potential contribution of macrophages to skeletal muscle hypertrophy is discussed on the basis of both animal and human experiments. We also present a brief comparative analysis of the role of macrophages during muscle regeneration versus hypertrophy. Finally, we summarize the current knowledge on the impact of different immunomodulatory strategies, such as heat therapy, cooling, massage, nonsteroidal anti-inflammatory drugs and resolvins, on skeletal muscle regeneration and their potential impact on muscle hypertrophy.

Chemerin as a Potential Marker of Resolution of Inflammation in COVID-19 Infection

Chemerin is one of the specialized pro-resolving mediators that participate in the early phase of inflammation and contribute to the initiation of the pro-resolving response. There is a paucity of data regarding the time course of chemerin during acute infections. We aimed to evaluate the sequence of inflammatory responses in the acute COVID-19 phase throughout onset and resolution of inflammation. We evaluated changes in selected biomarkers in COVID-19 survivors on the 7-day and 28-day follow up. Chemerin was lower in patients with baseline moderate/severe disease at day 7 compared with asymptomatic patients and individuals with mild illness (7265 [5526−9448] vs. 8730 [6888−11,058] pg/mL; p = 0.03). Only in patients with moderate/severe disease, but not in those with mild symptoms, were chemerin concentrations decreased one week after infection onset compared with baseline (7265 [5526−9448] vs. 8866 [6383−10,690] pg/mL; p < 0.05) with a subsequent increase on the 28-day follow up (9313 [7353−11,033] pg/mL; p < 0.05). Resolution of inflammation in the group of moderate/severe SARS-CoV2 infection was associated with increasing serum concentrations of chemerin, contrary to pro-inflammatory cytokines and adipokines (pentraxin 3, TNFα, resistin, leptin). A similar pattern of angiopoietin-2 dynamics may suggest signs of enhanced vascularization as a consequence of acute SARS-CoV2 infection.

Molecular Pharmacology of Inflammation Resolution in Atherosclerosis

Atherosclerosis is one of the most important problems of modern medicine as it is the leading cause of hospitalizations, disability, and mortality. The key role in the development and progression of atherosclerosis is the imbalance between the activation of inflammation in the vascular wall and the mechanisms of its control. The resolution of inflammation is the most important physiological mechanism that is impaired in atherosclerosis. The resolution of inflammation has complex, not fully known mechanisms, in which lipid mediators derived from polyunsaturated fatty acids (PUFAs) play an important role. Specialized pro-resolving mediators (SPMs) represent a group of substances that carry out inflammation resolution and may play an important role in the pathogenesis of atherosclerosis. SPMs include lipoxins, resolvins, maresins, and protectins, which are formed from PUFAs and regulate many processes related to the active resolution of inflammation. Given the physiological importance of these substances, studies examining the possibility of pharmacological effects on inflammation resolution are of interest.

The utilisation of resolvins in medicine and tissue engineering

Recent advances in the field of regenerative medicine and biomaterial science have highlighted the importance of controlling immune cell phenotypes at the biomaterial interface. These studies have clearly indicated that a rapid resolution of the inflammatory process, mediated by a switch in the macrophage population towards a reparative phenotype, is essential for tissue regeneration to occur. While various biomaterial surfaces have been developed in order to impart immunomodulatory properties to the resulting constructs, an alternative strategy involving the use of reparative biological cues, known as resolvins, is emerging in regenerative medicine. This review reports on the mechanisms via which resolvins participate in the resolution of inflammation and describes their current utilisation in pre-clinical and clinical settings, along with their effectiveness when combined with biomaterial constructs in tissue engineering applications. STATEMENT OF SIGNIFICANCE: The resolution of the inflammatory process is necessary for achieving tissue healing and regeneration. Resolvins are lipid mediators and play a key role in the resolution of the inflammatory response and can be used in as biological cues to promote tissue regeneration. This review describes the various biological inflammatory mechanisms and pathways involving resolvins and how their action results in a pro-healing response. The use of these molecules in the clinical setting is then summarised for various applications along with their limitations. Lastly, the review focuses on the emergence resolvins in tissue engineering products including the use of a more stable form which holds greater prospect for regenerative purposes.

Anti-Inflammatory Function of Fatty Acids and Involvement of Their Metabolites in the Resolution of Inflammation in Chronic Obstructive Pulmonary Disease

Lipid metabolism plays an important role in many lung functions. Disorders of lipid metabolism are part of the pathogenesis of chronic obstructive pulmonary disease (COPD). Lipids are involved in numerous cross-linkages with inflammation. Recent studies strongly support the involvement of fatty acids as participants in inflammation. They are involved in the initiation and resolution of inflammation, including acting as a substrate for the formation of lipid mediators of inflammation resolution. Specialized pro-inflammatory mediators (SPMs) belonging to the classes of lipoxins, resolvins, maresins, and protectins, which are formed enzymatically from unsaturated fatty acids, are now described. Disorders of their production and function are part of the pathogenesis of COPD. SPMs are currently the subject of active research in order to find new drugs. Short-chain fatty acids are another important participant in metabolic and immune processes, and their role in the pathogenesis of COPD is of great clinical interest.

Annexin A1 attenuates cardiac diastolic dysfunction in mice with inflammatory arthritis

Rheumatoid arthritis (RA) carries a twofold increased incidence of heart failure with preserved ejection fraction, accompanied by diastolic dysfunction, which can lead to death. The causes of diastolic dysfunction are unknown, and there are currently no well-characterized animal models for studying these mechanisms. Current medications for RA do not have marked beneficial cardio-protective effects. K/BxN F1 progeny and KRN control mice were analyzed over time for arthritis development, monitoring left ventricular diastolic and systolic function using echocardiography. Excised hearts were analyzed by flow cytometry, qPCR, and histology. In pharmacological experiments, K/BxN F1 mice were treated with human recombinant AnxA1 (hrAnxA1, 1 μg/mouse) or vehicle daily. K/BxN F1 mice exhibited fully developed arthritis with normal cardiac function at 4 wk; however, by week 8, all mice displayed left ventricular diastolic dysfunction with preserved ejection fraction. This dysfunction was associated with cardiac hypertrophy, myocardial inflammation and fibrosis, and inflammatory markers. Daily treatment of K/BxN F1 mice with hrAnxA1 from weeks 4 to 8 halted progression of the diastolic dysfunction. The treatment reduced cardiac transcripts of proinflammatory cytokines and profibrotic markers. At the cellular level, hrAnxA1 decreased activated T cells and increased MHC II^low macrophage infiltration in K/BxN F1 hearts. Similar effects were obtained when hrAnxA1 was administered from week 8 to week 15. We describe an animal model of inflammatory arthritis that recapitulates the cardiomyopathy of RA. Treatment with hrAnxA1 after disease onset corrected the diastolic dysfunction through modulation of both fibroblast and inflammatory cell phenotype within the heart.

Specialized Pro-Resolving Mediators Mitigate Cancer-Related Inflammation: Role of Tumor-Associated Macrophages and Therapeutic Opportunities

Inflammation is a fundamental physiological response orchestrated by innate immune cells to restore tissue homeostasis. Specialized pro-resolving mediators (SPMs) are involved in active resolution of inflammation but when inflammation is incomplete, chronic inflammation creates a favorable environment that fuels carcinogenesis and cancer progression. Conventional cancer therapy also strengthens cancer-related inflammation by inducing massive tumor cell death that activate surrounding immune-infiltrating cells such as tumor-associated macrophages (TAMs). Macrophages are key actors of both inflammation and its active resolution due to their plastic phenotype. In line with this high plasticity, macrophages can be hijacked by cancer cells to support tumor progression and immune escape, or therapy resistance. Impaired resolution of cancer-associated inflammation supported by TAMs may thus reinforces tumor progression. From this perspective, recent evidence suggests that stimulating macrophage's pro-resolving functions using SPMs can promote inflammation resolution in cancer and improve anticancer treatments. Thus, TAMs' re-education toward an antitumor phenotype by using SPMs opens a new line of attack in cancer treatment. Here, we review SPMs' anticancer capacities with special attention regarding their effects on TAMs. We further discuss how this new therapeutic approach could be envisioned in cancer therapy.

Potential role of bioactive lipids in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease, which involves a pathological inflammatory response against articular cartilage in multiple joints throughout the body. It is a complex disorder associated with comorbidities such as depression, lymphoma, osteoporosis and cardiovascular disease (CVD), which significantly deteriorate patients' quality of life and prognosis. This has ignited a large initiative to elucidate the physiopathology of RA, aiming to identify new therapeutic targets and approaches in its multidisciplinary management. Recently, various lipid bioactive products have been proposed to have an essential role in this process; including eicosanoids, specialized pro-resolving mediators, phospholipids/sphingolipids, and endocannabinoids. Dietary interventions using omega-3 polyunsaturated fatty acids or treatment with synthetic endocannabinoids agonists have been shown to significantly ameliorate RA symptoms. Indeed, the modulation of lipid metabolism may be crucial in the pathophysiology and treatment of autoimmune diseases.

COVID-19 severity in obese patients: Potential mechanisms and molecular targets for clinical intervention

With the global spread of SARS-CoV-2, millions of people have been affected leading to the declaration of coronavirus disease 2019 (COVID-19) as a pandemic by the WHO. Several studies have linked the severity of COVID-19 cases and increased fatality in patients with obesity and other comorbid conditions such as diabetes, cardiovascular diseases, hypertension, and kidney disease. Obesity, a metabolically deranged condition, establishes a low-grade chronic inflammation in the body, which affects different organs and promotes the development of several other diseases. The ways in which SARS-CoV-2 infection aggravates the already overloaded body organs with inflammation or vice versa has perplexed the researchers. As a result, there is an intensified search for the clear-cut mechanism to understand the link of obesity with the increased severity of COVID-19 in obese patients. In this article we have discussed various mechanisms linking obesity, inflammation, and COVID-19 to enhance the understanding of the disease process and help the clinicians and scientists develop potential cellular, molecular and metabolic targets for clinical intervention and management of COVID-19 severity in obese patients.

Could Arachidonic Acid-Derived Pro-Resolving Mediators Be a New Therapeutic Strategy for Asthma Therapy?

Asthma represents one of the leading chronic diseases worldwide and causes a high global burden of death and disability. In asthmatic patients, the exacerbation and chronification of the inflammatory response are often related to a failure in the resolution phase of inflammation. We reviewed the role of the main arachidonic acid (AA) specialized pro-resolving mediators (SPMs) in the resolution of chronic lung inflammation of asthmatics. AA is metabolized by two classes of enzymes, cyclooxygenases (COX), which produce prostaglandins (PGs) and thromboxanes, and lypoxygenases (LOX), which form leukotrienes and lipoxins (LXs). In asthma, two primary pro-resolving derived mediators from COXs are PGE₂ and the cyclopentenone prostaglandin15-Deoxy-Delta-12,14-PGJ₂ (15d-PGJ₂) while from LOXs are the LXA₄ and LXB₄. In different models of asthma, PGE₂, 15d-PGJ₂, and LXs reduced lung inflammation and remodeling. Furthermore, these SPMs inhibited chemotaxis and function of several inflammatory cells involved in asthma pathogenesis, such as eosinophils, and presented an antiremodeling effect in airway epithelial, smooth muscle cells and fibroblasts in vitro. In addition, PGE₂, 15d-PGJ₂, and LXs are all able to induce macrophage reprogramming to an alternative M2 pro-resolving phenotype in vitro and in vivo. Although PGE₂ and LXA₄ showed some beneficial effects in asthmatic patients, there are limitations to their clinical use, since PGE₂ caused side effects, while LXA₄ presented low stability. Therefore, despite the strong evidence that these AA-derived SPMs induce resolution of both inflammatory response and tissue remodeling in asthma, safer and more stable analogs must be developed for further clinical investigation of their application in asthma treatment.

Therapeutic Opportunities for Repair GPCRs during Intestinal Mucosal Wound Healing

G protein-coupled receptors (GPCRs) are crucial for establishing the resolution phase following an intestinal inflammatory episode. Because current treatments for intestinal inflammation have a high percentage of failure and lead to immunosuppression, repair GPCRs have promising therapeutic potential because they trigger resolution pathways without compromising the immune response.

The Anti-Inflammatory and Antioxidant Properties of n-3 PUFAs: Their Role in Cardiovascular Protection

Polyunsaturated fatty acids (n-3 PUFAs) are long-chain polyunsaturated fatty acids with 18, 20 or 22 carbon atoms, which have been found able to counteract cardiovascular diseases. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in particular, have been found to produce both vaso- and cardio-protective response via modulation of membrane phospholipids thereby improving cardiac mitochondrial functions and energy production. However, antioxidant properties of n-3 PUFAs, along with their anti-inflammatory effect in both blood vessels and cardiac cells, seem to exert beneficial effects in cardiovascular impairment. In fact, dietary supplementation with n-3 PUFAs has been demonstrated to reduce oxidative stress-related mitochondrial dysfunction and endothelial cell apoptosis, an effect occurring via an increased activity of endogenous antioxidant enzymes. On the other hand, n-3 PUFAs have been shown to counteract the release of pro-inflammatory cytokines in both vascular tissues and in the myocardium, thereby restoring vascular reactivity and myocardial performance. Here we summarize the molecular mechanisms underlying the anti-oxidant and anti-inflammatory effect of n-3 PUFAs in vascular and cardiac tissues and their implication in the prevention and treatment of cardiovascular disease.

GPCR-PEnDB: a database of protein sequences and derived features to facilitate prediction and classification of G protein-coupled receptors

G protein-coupled receptors (GPCRs) constitute the largest group of membrane receptor proteins in eukaryotes. Due to their significant roles in various physiological processes such as vision, smell and inflammation, GPCRs are the targets of many prescription drugs. However, the functional and sequence diversity of GPCRs has kept their prediction and classification based on amino acid sequence data as a challenging bioinformatics problem. There are existing computational approaches, mainly using machine learning and statistical methods, to predict and classify GPCRs based on amino acid sequence and sequence derived features. In this paper, we describe a searchable MySQL database, named GPCR-PEnDB (GPCR Prediction Ensemble Database), of confirmed GPCRs and non-GPCRs. It was constructed with the goal of allowing users to conveniently access useful information of GPCRs in a wide range of organisms and to compile reliable training and testing datasets for different combinations of computational tools. This database currently contains 3129 confirmed GPCR and 3575 non-GPCR sequences collected from the UniProtKB/Swiss-Prot protein database, encompassing over 1200 species. The non-GPCR entries include transmembrane proteins for evaluating various prediction programs' abilities to distinguish GPCRs from other transmembrane proteins. Each protein is linked to information about its source organism, classification, sequence lengths and composition, and other derived sequence features. We present examples of using this database along with its graphical user interface, to query for GPCRs with specific sequence properties and to compare the accuracies of five tools for GPCR prediction. This initial version of GPCR-PEnDB will provide a framework for future extensions to include additional sequence and feature data to facilitate the design and assessment of software tools and experimental studies to help understand the functional roles of GPCRs. Database URL: gpcr.utep.edu/database.

n-3 Docosapentaenoic acid-derived protectin D1 promotes resolution of neuroinflammation and arrests epileptogenesis

Epilepsy therapy is based on drugs that treat the symptoms rather than the underlying mechanisms of the disease (epileptogenesis). There are no treatments for preventing seizures or improving disease prognosis, including neurological comorbidities. The search of pathogenic mechanisms of epileptogenesis highlighted that neuroinflammatory cytokines [i.e. interleukin-1β (IL-1β), tumour necrosis factor-α (Tnf-α)] are induced in human and experimental epilepsies, and contribute to seizure generation in animal models. A major role in controlling the inflammatory response is played by specialized pro-resolving lipid mediators acting on specific G-protein coupled receptors. Of note, the role that these pathways have in epileptogenic tissue remains largely unexplored. Using a murine model of epilepsy, we show that specialized pro-resolving mechanisms are activated by status epilepticus before the onset of spontaneous seizures, but with a marked delay as compared to the neuroinflammatory response. This was assessed by measuring the time course of mRNA levels of 5-lipoxygenase (Alox5) and 15-lipoxygenase (Alox15), the key biosynthetic enzymes of pro-resolving lipid mediators, versus Il1b and Tnfa transcripts and proteins. In the same hippocampal tissue, we found a similar delayed expression of two main pro-resolving receptors, the lipoxin A₄ receptor/formyl peptide receptor 2 and the chemerin receptor. These receptors were also induced in the human hippocampus after status epilepticus and in patients with temporal lobe epilepsy. This evidence supports the hypothesis that the neuroinflammatory response is sustained by a failure to engage pro-resolving mechanisms during epileptogenesis. Lipidomic LC-MS/MS analysis showed that lipid mediator levels apt to resolve the neuroinflammatory response were also significantly altered in the hippocampus during epileptogenesis with a shift in the biosynthesis of several pro-resolving mediator families including the n-3 docosapentaenoic acid (DPA)-derived protectin D1. Of note, intracerebroventricular injection of this mediator during epileptogenesis in mice dose-dependently reduced the hippocampal expression of both Il1b and Tnfa mRNAs. This effect was associated with marked improvement in mouse weight recovery and rescue of cognitive deficit in the novel object recognition test. Notably, the frequency of spontaneous seizures was drastically reduced by 2-fold on average and the average seizure duration was shortened by 40% after treatment discontinuation. As a result, the total time spent in seizures was reduced by 3-fold in mice treated with n-3 DPA-derived protectin D1. Taken together, the present findings demonstrate that epilepsy is characterized by an inadequate engagement of resolution pathways. Boosting endogenous resolution responses significantly improved disease outcomes, providing novel treatment avenues.

The Autoimmune Susceptibility Gene C5orf30 Regulates Macrophage-Mediated Resolution of Inflammation

Genetic variants in C5orf30 have been associated with development of the autoimmune conditions primary biliary cirrhosis and rheumatoid arthritis. In rheumatoid arthritis, C5orf30 expression is cell-specific, with highest expression found in macrophages and synovial fibroblasts. C5orf30 is highly expressed in inflamed joints and is a negative regulator of tissue damage in a mouse model of inflammatory arthritis. Transcriptomic analysis from ultrasound-guided synovial biopsy of inflamed joints in a well characterized clinical cohort of newly diagnosed, disease-modifying antirheumatic drugs-naive rheumatoid arthritis patients was used to determine the clinical association of C5orf30 expression with disease activity. A combined molecular and computational biology approach was used to elucidate C5orf30 function in macrophages both in vitro and in vivo. Synovial expression of C5orf30 is inversely correlated with both clinical measures of rheumatoid arthritis disease activity and with synovial TNF mRNA expression. C5orf30 plays a role in regulating macrophage phenotype and is differentially turned over in inflammatory and anti-inflammatory macrophages. Inhibition of C5orf30 reduces wound healing/repair-associated functions of macrophages, reduces signaling required for resolution of inflammation, and decreases secretion of anti-inflammatory mediators. In an animal model of wound healing (zebrafish), C5orf30 inhibition increases the recruitment of macrophages to the wound site. Finally, we demonstrate that C5orf30 skews macrophage immunometabolism, demonstrating a mechanism for C5orf30-mediated immune regulation.

Specialized Pro-resolving Mediators Directs Cardiac Healing and Repair with Activation of Inflammation and Resolution Program in Heart Failure

After myocardial infarction, splenic leukocytes direct biosynthesis of specialized pro-resolving mediators (SPMs) that are essential for the resolution of inflammation and tissue repair. In a laboratory environment, after coronary ligation of healthy risk free rodents (young adult mice) leukocytes biosynthesize SPMs with induced activity of lipoxygenases and cyclooxygenases, which facilitate cardiac repair. Activated monocytes/macrophages drive the biosynthesis of SPMs following experimental myocardial infarction in mice during the acute heart failure. In the presented review, we provided the recent updates on SPMs (resolvins, lipoxins and maresins) in cardiac repair that may serve as novel therapeutics for future heart failure therapy/management. We incorporated the underlying causes of non-resolving inflammation following cardiac injury if superimposed with obesity, hypertension, diabetes, disrupted circadian rhythm, co-medication (painkillers or oncological therapeutics), and/or aging that may delay or impair the biosynthesis of SPMs, intensifying pathological remodeling in heart failure.

Opposing Effects on Vascular Smooth Muscle Cell Proliferation and Macrophage-induced Inflammation Reveal a Protective Role for the Proresolving Lipid Mediator Receptor ChemR23 in Intimal Hyperplasia

Intimal hyperplasia remains a significant clinical problem in for example coronary artery bypass graft failure. Since omega-3 fatty acids reduce intimal hyperplasia, we hypothesized that the G protein-coupled receptor ChemR23 for the omega-3-derived pro-resolving lipid mediator resolvin E1 drives those effects. ChemR23+/+ and ChemR23-/- mice were generated with or without introduction of the Caenorhabditis elegans fat-1 transgene, which leads to an endogenous omega-3 fatty acid synthesis and thus increasing the substrate for resolvin E1 formation. ChemR23 deletion significantly increased intimal hyperplasia 28 days after ligation of the left common carotid artery. Mice expressing the fat-1 transgene showed reduced intimal hyperplasia independently of ChemR23 expression. ChemR23-/- Vascular smooth muscle cells (VSMCs) exhibited a significantly lower proliferation compared with VSMCs derived from ChemR23+/+ mice. In contrast, ChemR23-/- peritoneal macrophages had significantly higher mRNA levels of pro-inflammatory cytokines compared with ChemR23+/+ macrophages. Finally, conditioned media (CM) transfer from ChemR23-/- macrophages to VSMCs significantly increased VSMC proliferation compared with CM from ChemR23+/+ macrophages. Taken together, these results point to a dual effect of ChemR23 in resolution pharmacology by directly stimulating VSMC proliferation and at the same time suppressing macrophage-induced VSMC proliferation. In conclusion, these differential effects of ChemR23 signaling in VSMC and macrophages open up a novel notion for intimal hyperplasia pathophysiology, where ChemR23-transduced effects on the vascular wall may vary, and even be opposing, depending on the degrees of resolution of inflammation.

Lipoxin and Resolvin Receptors Transducing the Resolution of Inflammation in Cardiovascular Disease

A non-resolving inflammation results in a chronic inflammatory response, characteristic of atherosclerosis, abdominal aortic aneurysms and several other cardiovascular diseases. Restoring the levels of specialized proresolving mediators to drive the chronic cardiovascular inflammation toward resolution is emerging as a novel therapeutic principle. The lipid mediators lipoxins and resolvins exert their proresolving actions through specific G-protein coupled receptors (GPCR). So far, four GPCR have been identified as the receptors for lipoxin A4 and the D- and E-series of resolvins, namely ALX/FPR2, DRV1/GPR32, DRV2/GPR18, and ERV1/ChemR23. At the same time, other pro-inflammatory ligands also activate some of these receptors. Recent studies of genetic targeting of these receptors in atherosclerotic mouse strains have revealed a major role for proresolving receptors in atherosclerosis. The present review addresses the complex pharmacology of these four proresolving GPCRs with focus on their therapeutic implications and opportunities for inducing the resolution of inflammation in cardiovascular disease.

Therapeutic Potential of Annexin A1 in Ischemia Reperfusion Injury

Cardiovascular disease (CVD) continues to be the leading cause of death in the world. Increased inflammation and an enhanced thrombotic milieu represent two major complications of CVD, which can culminate into an ischemic event. Treatment for these life-threatening complications remains reperfusion and restoration of blood flow. However, reperfusion strategies may result in ischemia-reperfusion injury (I/RI) secondary to various cardiovascular pathologies, including myocardial infarction and stroke, by furthering the inflammatory and thrombotic responses and delivering inflammatory mediators to the affected tissue. Annexin A1 (AnxA1) and its mimetic peptides are endogenous anti-inflammatory and pro-resolving mediators, known to have significant effects in resolving inflammation in a variety of disease models. Mounting evidence suggests that AnxA1, which interacts with the formyl peptide receptor (FPR) family, may have a significant role in mitigating I/RI associated complications. In this review article, we focus on how AnxA1 plays a protective role in the I/R based vascular pathologies.

Resolvin E1, resolvin D1 and resolvin D2 inhibit constriction of rat thoracic aorta and human pulmonary artery induced by the thromboxane mimetic U46619

BACKGROUND AND PURPOSE

The ω-6 fatty acid-derived lipid mediators such as prostanoids, thromboxane and leukotrienes have well-established roles in regulating both inflammation and smooth muscle contractility. Resolvins are derived from ω-3 fatty acids and have important roles in promoting the resolution of inflammation, but their activity on smooth muscle contractility is unknown. We investigated whether resolvin E1 (RvE1), resolvin D1 (RvD1) and resolvin D2 (RvD2) can modulate contractions of isolated segments of rat thoracic aorta (RTA) or human pulmonary artery (HPA) induced by the α₁ -adrenoceptor agonist phenylephrine or the stable thromboxane A₂ mimetic U46619.

EXPERIMENTAL APPROACH

Contractile responses in RTA and HPA were measured using wire myography. Receptor expression was investigated by immunohistochemistry.

KEY RESULTS

Constriction of RTA segments by U46619, but not by phenylephrine, was significantly inhibited by pretreatment for 1 or 24 h with 10-100 nM RvE1, RvD1 or RvD2. The inhibitory effect of RvE1 was partially blocked by a chemerin receptor antagonist (CCX832). RvE1 at only 1-10 nM also significantly inhibited U46619-induced constriction of HPA segments, and the chemerin receptor, GPR32 and FPR2/ALX were identified in HPA smooth muscle.

CONCLUSION AND IMPLICATIONS

These data suggest that resolvins or their mimetics may prove useful novel therapeutics in diseases such as pulmonary arterial hypertension, which are characterized by increased thromboxane contractile activity.

Function of Pro-Resolving Lipid Mediator Resolvin E1 in Type 2 Diabetes

Programming of inflammation resolution is governed by a class of specialized pro-resolving lipid mediators (SPMs) that act in concert to modulate epithelial, endothelial, and immune cell function for restoration of homeostasis. The resolution circuits are altered in obesity and associated morbidities, including type 2 diabetes mellitus (T2D), through reduced production and/or action of SPMs, which can be rescued by therapeutic SPM delivery or up-regulation of SPM receptors. Resolvin E1 (RvE1), an eicosapentaenoic acid derivative, has potent pro-resolving and insulin-sensitizing actions mediated by BLT1 and ERV1 receptors in the vasculature and metabolic organs. Nonetheless, the RvE1-mediated increase in protective adipokines such as adiponectin in white adipose tissues, the enhancement of monocyte patrolling function in the vasculature, as well as the macrophage-clearing functions improve metabolic control in obese-prone conditions. RvE1-enhanced resolving function in obesity prevents dysbiosis of the gut microflora and increased gut permeability. These functions suggest that RE1 has therapeutic potential for immunometabolic alterations associated with T2D in patients with reduced inflammation resolving capacity. SPM profiling in individuals at risk for T2D and associated complications will help to advance personalized disease management and precision medicine.

A model for the optimization of anti-inflammatory treatment with chemerin

Routine treatment of mild to moderate pain with a combination of non-steroidal anti-inflammatory drugs such as paracetamol in combination with corticoid opioids can lead to severe complications including death from gastrointestinal injury or to drug dependence. There is a need for the development of new safer drugs. Chemerin is a mediator promoting resolution of inflammation and it is then a promising candidate for a new treatment. A pilot experimental work using the zymosan-induced peritonitis model has found that injecting extra chemerin resulted in an approximately 1% reduction in the total number of inflammatory cells recruited. This paper combines and adapts existing mathematical models of inflammation to reproduce these results and to explore the therapeutic potential of chemerin through simulations. Analysis of the model predicts that the injection of chemerin at a concentration of 2000 ng ml^-1 within the first 5 min of inflammation onset leads to maximal inflammation inhibition. The degree of inhibition is shown to be sensitive to data used for the fit with a mean inhibition of 22 ± 3.7% for a series of remove-one bootstrap tests, whereas optimal chemerin injection parameters were not. Overall sensitivity analysis identifies parameters of the model that need to be measured more accurately or with increased sampling rate to improve model robustness and confirm chemerin's therapeutic potential.

ERV1 Overexpression in Myeloid Cells Protects against High Fat Diet Induced Obesity and Glucose Intolerance

Non-resolving inflammation is a central pathologic component of obesity, insulin resistance, type 2 diabetes and associated morbidities. The resultant hyperglycemia is deleterious to the normal function of many organs and its control significantly improves survival and quality of life for patients with diabetes. Macrophages play critical roles in both onset and progression of obesity-associated insulin resistance. Here we show that systemic activation of inflammation resolution prevents from morbid obesity and hyperglycemia under dietary overload conditions. In gain-of-function studies using mice overexpressing the human resolvin E1 receptor (ERV1) in myeloid cells, monocyte phenotypic shifts to increased patrolling-to-inflammatory ratio controlled inflammation, reduced body weight gain and protected from hyperglycemia on high-fat diet. Administration of a natural ERV1 agonist, resolvin E1, recapitulated the pro-resolving actions gained by ERV1 overexpression. This protective metabolic impact is in part explained by systemic activation of resolution programs leading to increased synthesis of specialized pro-resolving mediators.

Hydroalcoholic crude extract of Casearia sylvestris Sw. reduces chronic post-ischemic pain by activation of pro-resolving pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Casearia sylvestris Sw. is widely used in popular medicine to treat conditions associated with pain.

AIM OF THE STUDY

The present study investigated the influence of hydroalcoholic crude extract of Casearia sylvestris (HCE-CS) and contribution of pro-resolving mediators on mechanical hyperalgesia in a mouse model of chronic post-ischemia pain (CPIP).

METHODS AND RESULTS

Male Swiss mice were subjected to ischemia of the right hind paw (3h), then reperfusion was allowed. At 10min, 24h or 48h post-ischemia/reperfusion (I/R), different groups of animals were treated with HCE-CS (30mg/Kg, orally [p.o]), selected agonists at the pro-resolving receptor ALX/FPR2 (natural molecules like resolvin D1 and lipoxin A4 or the synthetic compound BML-111; 0.1-1µg/animal) or vehicle (saline, 10mL/Kg, s.c.), in the absence or presence of the antagonist WRW4 (10µg, s.c.). Mechanical hyperalgesia (paw withdrawal to von Frey filament) was asseseed together with histological and immunostainning analyses. In these settings, pro-resolving mediators reduced mechanical hyperalgesia and HCE-CS or BML-111 displayed anti-hyperalgesic effects which was markedly attenuated in animals treated with WRW4. ALX/FPR2 expression was raised in skeletal muscle or neutrophils after treatment with HCE-CS or BML-111.

CONCLUSION

These results reveal significant antihyperalgesic effect of HCE-CS on CPIP, mediated at least in part, by the pathway of resolution of inflammation centred on the axis modulated by ALX/FPR2.

Fine-tuning inflammation-resolution programs: focus on atherosclerosis

PURPOSE OF REVIEW

Nonresolving inflammation is now considered the underpinning of several prevalent human diseases, including atherosclerosis. The resolution of inflammation is a highly coordinated program to counterbalance proinflammatory signals for a swift return to tissue homeostasis. This process is controlled in part by endogenous specialized proresolving lipid mediators (SPMs). Emerging evidence has revealed that the balance of SPMs and proinflammatory mediators during acute inflammation regulates the duration of the inflammatory response and the timing of tissue resolution. Moreover, an imbalance between SPMs and proinflammatory mediators has been linked to several prevalent chronic inflammatory diseases in humans, including atherosclerosis.

RECENT FINDINGS

Lipid mediator imbalances have recently been linked to atherosclerotic plaque instability. Administration of key SPMs restored this imbalance and led to plaque stability. SPMs have also recently been shown to be protective in other cardiovascular disease models including myocardial infarction, stroke and neointimal hyperplasia.

SUMMARY

The current review highlights recent work that supports the concept of dysregulated inflammation-resolution in atherosclerosis with a particular focus on mechanisms and therapeutic opportunities associated with SPM receptors and lipid mediator imbalances. This article is based on experimental studies.

Formyl peptide receptor 1 suppresses gastric cancer angiogenesis and growth by exploiting inflammation resolution pathways

Chronic inflammation can result from inadequate engagement of resolution mechanisms, mainly accomplished by specialized pro-resolving mediators (SPMs) arising from the metabolic activity of lipoxygenases (ALOX5/15) on ω-6 or ω-3 essential polyunsaturated fatty acids (PUFA). We previously demonstrated that formyl peptide receptor 1 (FPR1) suppresses gastric cancer (GC) by inhibiting its inflammatory/angiogenic potential. In this study, we asked whether FPR1 exploits inflammation resolution pathways to suppress GC angiogenesis and growth. Here, we demonstrate that genetic or pharmacologic modulation of FPR1 in GC cells regulated ALOX5/15 expression and production of the SPMs Resolvin D1 (RvD1) and Lipoxin B4 (LXB4). SPM treatment of GC cells abated their angiogenic potential. Genetic deletion of ALOX15 or of the RvD1 receptor GPR32 increased the angiogenic and tumorigenic activity of GC cells thereby mimicking FPR1 loss. Deletion/inhibition of ALOX5/15 or GPR32 blocked FPR1-mediated anti-angiogenic activities, indicating that ALOX5/15 and GPR32 are required for FPR1's pro-resolving action. An ω-3- or ω-6-enriched diet enforced SPM endogenous production in mice and inhibited growth of shFPR1 GC xenografts by suppressing their angiogenic activity. These data implicate that FPR1 and/or pro-resolving pathway components might be used as risk/prognostic markers for GC; ω-6/3-enriched diets, and targeting FPR1 or SPM machinery may be exploited for GC management.

Small-molecule-biased formyl peptide receptor agonist compound 17b protects against myocardial ischaemia-reperfusion injury in mice

Effective treatment for managing myocardial infarction (MI) remains an urgent, unmet clinical need. Formyl peptide receptors (FPR) regulate inflammation, a major contributing mechanism to cardiac injury following MI. Here we demonstrate that FPR1/FPR2-biased agonism may represent a novel therapeutic strategy for the treatment of MI. The small-molecule FPR1/FPR2 agonist, Compound 17b (Cmpd17b), exhibits a distinct signalling fingerprint to the conventional FPR1/FPR2 agonist, Compound-43 (Cmpd43). In Chinese hamster ovary (CHO) cells stably transfected with human FPR1 or FPR2, Compd17b is biased away from potentially detrimental FPR1/2-mediated calcium mobilization, but retains the pro-survival signalling, ERK1/2 and Akt phosphorylation, relative to Compd43. The pathological importance of the biased agonism of Cmpd17b is demonstrable as superior cardioprotection in both in vitro (cardiomyocytes and cardiofibroblasts) and MI injury in mice in vivo. These findings reveal new insights for development of small molecule FPR agonists with an improved cardioprotective profile for treating MI.

G Protein-Coupled Receptors (GPCRs) can adopt different conformations, each linked to distinct cellular outcomes. Here the authors show that compound 17b, a novel agonist of the GPCR family member FPR, robustly activates cardioprotective but not detrimental FPR signalling, showing beneficial therapeutic effect in a mouse model of cardiac infarction.

Triggering receptor expressed on myeloid cells and 5'adenosine monophosphate-activated protein kinase in the inflammatory response: a potential therapeutic target

INTRODUCTION

The events in the cellular and molecular signaling triggered during inflammation mitigate tissue healing. The metabolic check-point control mediated by 5'-adenosine monophosphate-activated protein kinase (AMPK) is crucial for switching the cells into an activated state capable of mediating inflammatory events. The cell metabolism involved in the inflammatory response represents a potential therapeutic target for the pharmacologic management of inflammation. Areas covered: In this article, a critical review is presented on triggering receptor expressed on myeloid cell (TREM) receptors and their role in the inflammatory responses, as well as homeostasis between different TREM molecules and their regulation. Additionally, we discussed the relationship between TREM and AMPK to identify novel targets to limit the inflammatory response. Literature search was carried out from the National Library of Medicine's Medline database (using PubMed as the search engine) and Google Scholar and identified relevant studies up to 30 March 2016 using inflammation, TREM, AMPK, as the key words. Expert commentary: The prevention of phenotype switching of immune cells during inflammation by targeting AMPK and TREM-1 could be beneficial for developing novel management strategies for inflammation and associated complications.

The peptidomimetic Lau-(Lys-βNSpe)6-NH2 antagonizes formyl peptide receptor 2 expressed in mouse neutrophils

The formyl peptide receptor (FPR) gene family has a complex evolutionary history and comprises eight murine members but only three human representatives. To enable translation of results obtained in mouse models of human diseases, more comprehensive knowledge of the pharmacological similarities/differences between the human and murine FPR family members is required. Compared to FPR1 and FPR2 expressed by human neutrophils, very little is known about agonist/antagonist recognition patterns for their murine orthologues, but now we have identified two potent and selective formylated peptide agonists (fMIFL and PSMα2) for Fpr1 and Fpr2, respectively. These peptides were used to determine the inhibition profile of a set of antagonists with known specificities for the two FPRs in relation to the corresponding murine receptors. Some of the most potent and selective antagonists for the human receptors proved to be devoid of effect on their murine orthologues as determined by their inability to inhibit superoxide release from murine neutrophils upon stimulation with receptor-specific agonists. The Boc-FLFLF peptide was found to be a selective antagonist for Fpr1, whereas the lipidated peptidomimetic Lau-(Lys-βNSpe)₆-NH₂ and the hexapeptide WRW₄ were identified as Fpr2-selective antagonists.

Resolution of inflammation: a new therapeutic frontier

Dysregulated inflammation is a central pathological process in diverse disease states. Traditionally, therapeutic approaches have sought to modulate the pro- or anti-inflammatory limbs of inflammation, with mixed success. However, insight into the pathways by which inflammation is resolved has highlighted novel opportunities to pharmacologically manipulate these processes - a strategy that might represent a complementary (and perhaps even superior) therapeutic approach. This Review discusses the state of the art in the biology of resolution of inflammation, highlighting the opportunities and challenges for translational research in this field.

Resolvin D1, resolvin D2 and maresin 1 activate the GSK3β anti-inflammatory axis in TLR4-engaged human monocytes

Pro-resolving, docosahexaenoic acid-derived mediators have recently emerged as important potential therapeutic agents for the amelioration of complications arising from inflammation, such as vascular disease, asthma, acute lung injury and colitis. While resolvin D1 (RVD1), resolvin D2 (RVD2) and maresin 1 (MaR1) are established pro-resolvins, their mechanisms of action remain unclear. Here we show that, in LPS-stimulated primary human monocytes, RVD1, RVD2 and MaR1 each suppress the release of pro-inflammatory cytokines (TNF, IL-1β, IL-8) and the innate/adaptive bridging cytokine, IL-12 p40, while simultaneously augmenting the production of the anti-inflammatory cytokine, IL-10. Such resolving activity is accompanied by the increased phosphorylation (enhanced anti-inflammatory state) of glycogen synthase kinase 3β (GSK3β) along with increased phosphorylation (activation) of Akt, SGK1 and CREB but not MAPK-related molecules. Gain and loss of function experiments confirm a key role for GSK3β and CREB in the anti-inflammatory actions of resolvins. These results suggest that induction of the GSK3β anti-inflammatory axis is a common mechanism of action for RVD1, RVD2 and MaR1.

Formyl peptide receptors at the interface of inflammation, angiogenesis and tumor growth

N-formyl peptide receptors (FPRs) belong to the family of pattern recognition receptors (PRRs) that regulate innate immune responses. Three FPRs have been identified in humans: FPR1-FPR3. FPR expression was initially described in immune cells and subsequently in non-hematopoietic cells and certain tissues. Besides their involvement in inflammatory disorders, FPRs have been implicated in the regulation of tissue repair and angiogenesis. Angiogenesis is not only a key component of pathogen defence during acute infection and of chronic inflammatory disorders, but also plays a critical role in wound healing and tissue regeneration. Moreover, pathologic uncontrolled angiogenesis is central for tumour growth, progression, and the formation of metastases. In this review, we summarise the evidence for a central role of FPRs at the intersection between inflammation, physiologic angiogenesis and pathologic neovascularisation linked to cancer. These findings provide insights into the potential clinical relevance of new treatment regimens involving FPR modulation.

Curbing Inflammation in Multiple Sclerosis and Endometriosis: Should Mast Cells Be Targeted?

Inflammatory diseases and conditions can arise due to responses to a variety of external and internal stimuli. They can occur acutely in response to some stimuli and then become chronic leading to tissue damage and loss of function. While a number of cell types can be involved, mast cells are often present and can be involved in the acute and chronic processes. Recent studies in porcine and rabbit models have supported the concept of a central role for mast cells in a “nerve-mast cell-myofibroblast axis” in some inflammatory processes leading to fibrogenic outcomes. The current review is focused on the potential of extending aspects of this paradigm into treatments for multiple sclerosis and endometriosis, diseases not usually thought of as having common features, but both are reported to have activation of mast cells involved in their respective disease processes. Based on the discussion, it is proposed that targeting mast cells in these diseases, particularly the early phases, may be a fruitful avenue to control the recurring inflammatory exacerbations of the conditions.

The Deleterious Effects of Oxidative and Nitrosative Stress on Palmitoylation, Membrane Lipid Rafts and Lipid-Based Cellular Signalling: New Drug Targets in Neuroimmune Disorders

Oxidative and nitrosative stress (O&NS) is causatively implicated in the pathogenesis of Alzheimer's and Parkinson's disease, multiple sclerosis, chronic fatigue syndrome, schizophrenia and depression. Many of the consequences stemming from O&NS, including damage to proteins, lipids and DNA, are well known, whereas the effects of O&NS on lipoprotein-based cellular signalling involving palmitoylation and plasma membrane lipid rafts are less well documented. The aim of this narrative review is to discuss the mechanisms involved in lipid-based signalling, including palmitoylation, membrane/lipid raft (MLR) and n-3 polyunsaturated fatty acid (PUFA) functions, the effects of O&NS processes on these processes and their role in the abovementioned diseases. S-palmitoylation is a post-translational modification, which regulates protein trafficking and association with the plasma membrane, protein subcellular location and functions. Palmitoylation and MRLs play a key role in neuronal functions, including glutamatergic neurotransmission, and immune-inflammatory responses. Palmitoylation, MLRs and n-3 PUFAs are vulnerable to the corruptive effects of O&NS. Chronic O&NS inhibits palmitoylation and causes profound changes in lipid membrane composition, e.g. n-3 PUFA depletion, increased membrane permeability and reduced fluidity, which together lead to disorders in intracellular signal transduction, receptor dysfunction and increased neurotoxicity. Disruption of lipid-based signalling is a source of the neuroimmune disorders involved in the pathophysiology of the abovementioned diseases. n-3 PUFA supplementation is a rational therapeutic approach targeting disruptions in lipid-based signalling.

The evolution of our understanding of macrophages and translation of findings toward the clinic

'There is at bottom only one genuinely scientific treatment for all diseases, and that is to stimulate the phagocytes,' so declaimed Sir Ralph Bloomfield Bonington in The Doctor's Dilemma, Act 1, by George Bernard Shaw (1906). More often nowadays, the need is to calm the phagocytes, given their role in inflammation and tissue damage. In spite of the growth of cellular and molecular information gained from studies in macrophage cell culture, mouse models and, to a lesser extent, human investigations, and the importance of macrophages in pathogenesis in a wide range of chronic disease processes, there is still a substantial shortfall in terms of clinical applications. In this review, we summarize concepts derived from macrophage studies and suggest possible properties suitable for diagnosis, prognosis and selective targeting of macrophage pathogenic functions.