The pro-resolving lipid mediator Maresin 1 protects against cerebral ischemia/reperfusion injury by attenuating the pro-inflammatory response

Is Lipid Metabolism of Value in Cancer Research and Treatment? Part II: Role of Specialized Pro-Resolving Mediators in Inflammation, Infections, and Cancer

Acute inflammation is the body's first defense in response to pathogens or injury that is partially governed by a novel genus of endogenous lipid mediators that orchestrate the resolution of inflammation, coined specialized pro-resolving mediators (SPMs). SPMs, derived from omega-3-polyunstaturated fatty acids (PUFAs), include the eicosapentaenoic acid-derived and docosahexaenoic acid-derived Resolvins, Protectins, and Maresins. Herein, we review their biosynthesis, structural characteristics, and therapeutic effectiveness in various diseases such as ischemia, viral infections, periodontitis, neuroinflammatory diseases, cystic fibrosis, lung inflammation, herpes virus, and cancer, especially focusing on therapeutic effectiveness in respiratory inflammation and ischemia-related injuries. Resolvins are sub-nanomolar potent agonists that accelerate the resolution of inflammation by reducing excessive neutrophil infiltration, stimulating macrophage functions including phagocytosis, efferocytosis, and tissue repair. In addition to regulating neutrophils and macrophages, Resolvins control dendritic cell migration and T cell responses, and they also reduce the pro-inflammatory cytokines, proliferation, and metastasis of cancer cells. Importantly, several lines of evidence have demonstrated that Resolvins reduce tumor progression in melanoma, oral squamous cell carcinoma, lung cancer, and liver cancer. In addition, Resolvins enhance tumor cell debris clearance by macrophages in the tumor's microenvironment. Resolvins, with their unique stereochemical structure, receptors, and biosynthetic pathways, provide a novel therapeutical approach to activating resolution mechanisms during cancer progression.

Ischemic Brain Injury: Involvement of Lipids in the Pathophysiology of Stroke and Therapeutic Strategies

Stroke is a devastating neurological disorder that is characterized by the sudden disruption of blood flow to the brain. Lipids are essential components of brain structure and function and play pivotal roles in stroke pathophysiology. Dysregulation of lipid signaling pathways modulates key cellular processes such as apoptosis, inflammation, and oxidative stress, exacerbating ischemic brain injury. In the present review, we summarize the roles of lipids in stroke pathology in different models (cell cultures, animal, and human studies). Additionally, the potential of lipids, especially polyunsaturated fatty acids, to promote neuroprotection and their use as biomarkers in stroke are discussed.

Maresin1 alleviates neuroinflammation by inhibiting caspase-3/ GSDME-mediated pyroptosis in mice cerebral ischemia-reperfusion model

OBJECTIVE

To explore the mechanism of Maresin1 in reducing cerebral ischemia-reperfusion injury.

MATERIALS AND METHODS

Male C57BL/6 mice were randomly divided (n = 5 in each group), and focal middle cerebral artery occlusion (MCAO) model was used to simulate cerebral ischemia/reperfusion injury. TTC and the Longa score were used to detect the degree of neurological deficits. Western blot was used to detect the expression levels of GSDME, GSDME-N, caspase-3 and cleaved caspase-3 in cerebral ischemic penumbra tissue, and immunofluorescence was used to detect the expression levels of GSDME-N. The mRNA expression levels of GSDME and pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) were detected by RT-PCR.

RESULTS

Compared with sham group, GSDME mRNA levels in MCAO group were significantly increased at 12 h and 24 h after reperfusion, and GSDME and GSDME-N significantly increased at 6-48 h after reperfusion. Compared with sham group, the percentage of infarct size, the Longa score, the mRNA expression levels of IL-1β, IL-6 and TNF-α, and GSDME, GSDME-N, caspase-3 and cleaved caspase-3 in MCAO group was significantly increased. Then, the percentage of infarct size and the Longa score significantly decreased after MaR1 administration, the mRNA expression levels of IL-1β and IL-6 downregulated, and GSDME, GSDME-N, caspase-3 and cleaved caspase-3 were also reduced. After administration of Z-DEVD-FMK(ZDF), the expression of caspase-3, cleaved caspase-3 and GSDME-N was decreased, which in MCAO+MaR1+ZDF group was not statistically significant compared with MCAO+ ZDF group.

CONCLUSION

Maresin1 alleviates cerebral ischemia/reperfusion injury by inhibiting pyroptosis mediated by caspase-3/GSDME pathway and alleviating neuroinflammation.

Maresin 1 Activates LGR6 to Alleviate Neuroinflammation via the CREB/JMJD3/IRF4 Pathway in a Rat Model of Subarachnoid Hemorrhage

Neuroinflammation is an early event of brain injury after subarachnoid hemorrhage (SAH). Whether the macrophage mediators in resolving inflammation 1 (MaR1) is involved in SAH pathogenesis is unknown. In this study, 205 male Sprague-Dawley rats were subjected to SAH via endovascular perforation in the experimental and control groups. MaR1 was dosed intranasally at 1 h after SAH, with LGR6 siRNA and KG-501, GSK-J4 administered to determine the signaling pathway. Neurobehavioral, histological and biochemical data were obtained from the animal groups with designated treatments. The results showed: (i) The leucine-rich repeat containing G protein-coupled receptor 6 (LGR6) was decreased after SAH and reached to the lowest level at 24 h after SAH. Jumonji d3 (JMJD3) protein levels tended to increase and peaked at 24 h after SAH. LGR6 and JMJD3 expression were co-localized with microglia. (ii) MaR1 administration mitigated short-term neurological deficits, brain edema and long-term neurobehavioral performance after SAH, and attenuated microglial activation and neutrophil infiltration. (iii) Knockdown of LGR6, inhibition of CREB phosphorylation or JMJD3 activity abolished the anti-neuroinflammatory effect of MaR1 on the expression of CREB, CBP, JMJD3, IRF4, IRF5, IL-1β, IL-6 and IL-10, thus prevented microglial activation and neutrophil infiltration. Together, the results show that MaR1 can activate LGR6 and affect CREB/JMJD3/IRF4 signaling to attenuate neuroinflammation after SAH, pointing to a potential pharmacological utility in this disorder.

The role of polyunsaturated fatty acids in the neurobiology of major depressive disorder and suicide risk

Long-chain polyunsaturated fatty acids (LC-PUFAs) are obtained from diet or derived from essential shorter-chain fatty acids, and are crucial for brain development and functioning. Fundamentally, LC-PUFAs' neurobiological effects derive from their physicochemical characteristics, including length and double bond configuration, which differentiate LC-PUFA species and give rise to functional differences between n(omega)-3 and n-6 LC-PUFAs. LC-PUFA imbalances are implicated in psychiatric disorders, including major depression and suicide risk. Dietary intake and genetic variants in enzymes involved in biosynthesis of LC-PUFAs from shorter chain fatty acids influence LC-PUFA status. Domains impacted by LC-PUFAs include 1) cell signaling, 2) inflammation, and 3) bioenergetics. 1) As major constituents of lipid bilayers, LC-PUFAs are determinants of cell membrane properties of viscosity and order, affecting lipid rafts, which play a role in regulation of membrane-bound proteins involved in cell-cell signaling, including monoaminergic receptors and transporters. 2) The n-3:n-6 LC-PUFA balance profoundly influences inflammation. Generally, metabolic products of n-6 LC-PUFAs (eicosanoids) are pro-inflammatory, while those of n-3 LC-PUFAs (docosanoids) participate in the resolution of inflammation. Additionally, n-3 LC-PUFAs suppress microglial activation and the ensuing proinflammatory cascade. 3) N-3 LC-PUFAs in the inner mitochondrial membrane affect oxidative stress, suppressing production of and scavenging reactive oxygen species (ROS), with neuroprotective benefits. Until now, this wealth of knowledge about LC-PUFA biomechanisms has not been adequately tapped to develop translational studies of LC-PUFA clinical effects in humans. Future studies integrating neurobiological mechanisms with clinical outcomes may suggest ways to identify depressed individuals most likely to respond to n-3 LC-PUFA supplementation, and mechanistic research may generate new treatment strategies.

Resolvin D1 Induces mTOR-independent and ATG5-dependent Autophagy in BV-2 Microglial Cells

OBJECTIVE

The activation state of microglia is known to occupy a central position in the pathophysiological process of cerebral inflammation. Autophagy is a catabolic process responsible for maintaining cellular homeostasis. In recent years, autophagy has been demonstrated to play an important role in neuroinflammation. Resolvin D1 (RvD1) is a promising therapeutic mediator that has been shown to exert substantial anti-inflammatory and proresolving activities. However, whether RvD1-mediated resolution of inflammation in microglia is related to autophagy regulation needs further investigation. The present study aimed to explore the effect of RvD1 on microglial autophagy and its corresponding pathways.

METHODS

Mouse microglial cells (BV-2) were cultured, treated with RvD1, and examined by Western blotting, confocal immunofluorescence microscopy, transmission electron microscopy, and flow cytometry.

RESULTS

RvD1 promoted autophagy in both BV-2 cells and mouse primary microglia by favoring the maturation of autophagosomes and their fusion with lysosomes. Importantly, RvD1 had no significant effect on the activation of mammalian target of rapamycin (mTOR) signaling. Furthermore, RvD1-induced mTOR-independent autophagy was confirmed by observing reduced cytoplasmic calcium levels and suppressed calcium/calmodulin-dependent protein kinase II (CaMK II) activation. Moreover, by downregulating ATG5, the increased phagocytic activity induced by RvD1 was demonstrated to be tightly controlled by ATG5-dependent autophagy.

CONCLUSION

The present work identified a previously unreported mechanism responsible for the role of RvD1 in microglial autophagy, highlighting its therapeutic potential against neuroinflammation.

Maresin: Macrophage Mediator for Resolving Inflammation and Bridging Tissue Regeneration-A System-Based Preclinical Systematic Review

Maresins are lipid mediators derived from omega-3 fatty acids with anti-inflammatory and pro-resolving properties, capable of promoting tissue regeneration and potentially serving as a therapeutic agent for chronic inflammatory diseases. The aim of this review was to systematically investigate preclinical and clinical studies on maresin to inform translational research. Two independent reviewers performed comprehensive searches with the term "Maresin (NOT) Review" on PubMed. A total of 137 studies were included and categorized into 11 human organ systems. Data pertinent to clinical translation were specifically extracted, including delivery methods, optimal dose response, and specific functional efficacy. Maresins generally exhibit efficacy in treating inflammatory diseases, attenuating inflammation, protecting organs, and promoting tissue regeneration, mostly in rodent preclinical models. The nervous system has the highest number of original studies (n = 25), followed by the cardiovascular system, digestive system, and respiratory system, each having the second highest number of studies (n = 18) in the field. Most studies considered systemic delivery with an optimal dose response for mouse animal models ranging from 4 to 25 μg/kg or 2 to 200 ng via intraperitoneal or intravenous injection respectively, whereas human in vitro studies ranged between 1 and 10 nM. Although there has been no human interventional clinical trial yet, the levels of MaR1 in human tissue fluid can potentially serve as biomarkers, including salivary samples for predicting the occurrence of cardiovascular diseases and periodontal diseases; plasma and synovial fluid levels of MaR1 can be associated with treatment response and defining pathotypes of rheumatoid arthritis. Maresins exhibit great potency in resolving disease inflammation and bridging tissue regeneration in preclinical models, and future translational development is warranted.

Maresin1 can be a potential therapeutic target for nerve injury

Nerve injury significantly affects human motor and sensory function due to destruction of the integrity of nerve structure. In the wake of nerve injury, glial cells are activated, and synaptic integrity is destroyed, causing inflammation and pain hypersensitivity. Maresin1, an omega-3 fatty acid, is a derivative of docosahexaenoic acid. It has showed beneficial effects in several animal models of central and peripheral nerve injuries. In this review, we summarize the anti-inflammatory, neuroprotective and pain hypersensitivity effects of maresin1 in nerve injury and provide a theoretical basis for the clinical treatment of nerve injury using maresin1.

Major depressive disorder (mdd): emerging immune targets at preclinical level

BACKGROUND

Major depressive disorder is a mental health disorder that is characterized by a persistently low mood and loss of interest. MDD is affecting over 3.8% of the global population as a major health problem. Its etiology is complex, and involves the interaction between a number of factors, including genetic predisposition and the presence of environmental stresses.

AREAS COVERED

The role of the immune and inflammatory systems in depression has been gaining interest, with evidence suggesting the potential involvement of pro-inflammatory molecules like TNF, interleukins, prostaglandins, and other cytokines, among others, has been put forth. Along with this, the potential of agents, from NSAIDs to antibiotics, are being evaluated in therapy for depression. The current review will discuss emerging immune targets at the preclinical level.

EXPERT OPINION

With increasing evidence to show that immune and inflammatory mediators are implicated in MDD, increasing research toward their potential as drug targets is encouraged. At the same time, agents acting on these mediators and possessing anti-inflammatory potential are also being evaluated as future therapeutic options for MDD, and increasing focus toward non-conventional drugs which can act through these mechanisms is important as regards the future prospects of the use of anti-inflammatory agents in depression.

Application of regulation of reactive oxygen species and lipid peroxidation to disease treatment

Although many diseases in which reactive oxygen species (ROS) and free radicals are involved in their pathogenesis are known, and antioxidants that effectively capture ROS have been identified and developed, there are only a few diseases for which antioxidants have been used for treatment. Here, we discuss on the following four concepts regarding the development of applications for disease treatment by regulating ROS, free radicals, and lipid oxidation with the findings of our research and previous reports. Concept 1) Utilization of antioxidants for disease treatment. In particular, the importance of the timing of starting antioxidant will be discussed. Concept 2) Therapeutic strategies using ROS and free radicals. Methods of inducing ferroptosis, which has been advocated as an iron-dependent cell death, are mentioned. Concept 3) Treatment with drugs that inhibit the synthesis of lipid mediators. In addition to the reduction of inflammatory lipid mediators by inhibiting cyclooxygenase and leukotriene synthesis, we will introduce the possibility of disease treatment with lipoxygenase inhibitors. Concept 4) Disease treatment by inducing the production of useful lipid mediators for disease control. We describe the treatment of inflammatory diseases utilizing pro-resolving mediators and propose potential compounds that activate lipoxygenase to produce these beneficial mediators.

Lipid metabolism and retinal diseases

PURPOSE

The retina has enormous lipids demands and must meet those needs. Retinal lipid homeostasis appears to be based on the symbiosis between neurons, Müller glial cells (MGC), and retinal pigment epithelium (RPE) cells, which can be impacted in several retinal diseases. The current research challenge is to better understand lipid-related mechanisms involved in retinal diseases, such as age-related macular degeneration (AMD) and glaucoma.

RESULTS

In a first axis, in vitro and focus on Müller glial cell, we aimed to characterize whether the 24S-hydroxycholesterol (24S-OHC), an overexpressed end-product of cholesterol elimination pathway in neural tissue and likely produced by suffering retinal ganglion cells in glaucoma, may modulate MGC membrane organization, such as lipid rafts, to trigger cellular signalling pathways related to retinal gliosis. We have found that lipid composition appears to be a key factor of membrane architecture, especially for lipid raft microdomain formation, in MGC. However, 24S-OHC did not appear to trigger retinal gliosis via the modulation of lipid or protein composition within lipid rafts microdomains. This study provided a better understanding of the complex mechanisms involved in the pathophysiology of glaucoma. On a second clinical ax, we focused on the lipid-related mechanisms involved in the dysfunction of aging RPE and the appearance of drusenoid deposits in AMD. Using the Montrachet population-based study, we intend to report the frequency of reticular pseudodrusen (RPD) and its ocular and systemic risk factors, particularly related to lipid metabolisms, such as plasma lipoprotein levels, carotenoids levels, and lipid-lowering drug intake. Our study showed that RPD was less common in subjects taking lipid-lowering drugs. Lipid-lowering drugs, such as statins, may reduce the risk of RPD through their effect on the production and function of lipoproteins. This observation highlights the potential role of retinal lipid trafficking via lipoproteins between photoreceptors and retinal pigment epithelium cells in RPD formation. Those findings have been complemented with preliminary results on the analysis of plasma fatty acid (FA) profile, a surrogate marker of short-term dietary lipid intake, according to the type of predominant drusenoid deposit, soft drusen or RPD, in age-related maculopathy.

CONCLUSION

Further research on lipid metabolism in retinal diseases is warranted to better understand the pathophysiology of retinal diseases and develop new promising diagnostic, prognostic, and therapeutic tools for our patients.

A cell-free difunctional demineralized bone matrix scaffold enhances the recruitment and osteogenesis of mesenchymal stem cells by promoting inflammation resolution

The dialogue between host macrophages (Mφs) and endogenous mesenchymal stem cells (MSCs) promotes M2 Mφs polarization to resolve early-stage inflammation, thereby effectively guiding in situ bone regeneration. Once inflammation is unresolved/incontrollable, it will induce the impediment of MSCs homing at bone defect site, implying the seasonable resolution of inflammation in balancing bone homeostasis. Repeatedly, evidence elucidated that specialized pro-resolving mediators (SPMs) could conduce to proper resolve inflammation and promote the repairing of bone defect. A difunctional demineralized bone matrix (DBM) scaffold co-modified by maresin 1 (MaR1) and aptamer 19S (Apt19S) was fabricated to facilitate the osteogenesis of MSCs. To confirm the osteogenesis and immunomodulatory role of the difunctional DBM scaffold, the proliferation, recruitment, and osteogenic differentiation of MSCs and the Mφs M2 subtype polarization were evaluated in vitro. Then, the DBM scaffolds were implanted into mice model with critical size calvarial defect to evaluate bone repair efficiency. Finally, the specific resolution mechanism in Mφs cultured on the difunctional DBM scaffold was further in-depth investigated. This difunctional DBM scaffold exhibited an enhanced function on the recruitment, proliferation, migration, osteogenesis of MSCs and the resolution of inflammation, finally improved bone-scaffold integration. At the same time, MaR1 modified on the difunctional DBM scaffold increased the biosynthesis of 12-lipoxygenase (12-LOX) and 12S-hydroxy-eicosatetraenoic acid (12S-HETE), and also directly stimulated lipid droplets (LDs) biogenesis in Mφs, which suggested that MaR1 regulated Mφ lipid metabolism at bone repair site. Findings based on this synergy strategy demonstrated that Mφ lipid metabolism was essential in bone homeostasis, which might provide a theoretical direction for the treatment-associated application of MaR1 in inflammatory bone disease.

Specialized Pro-Resolving Mediators in Neuroinflammation: Overview of Studies and Perspectives of Clinical Applications

Specialized pro-resolving mediators (SPMs) are lipid mediators derived from poly-unsaturated fatty acids (PUFAs) which have been demonstrated to have an important role in the inflammation environment, preventing an overreaction of the organism and promoting the resolution of inflammation. Our purpose was to point out the current evidence for specialized pro-resolving mediators, focusing on their role in neuroinflammation and in major neurological diseases.

Neuroprotective Effects of TRPM7 Deletion in Parvalbumin GABAergic vs. Glutamatergic Neurons following Ischemia

Oxidative stress induced by brain ischemia upregulates transient receptor potential melastatin-like-7 (TRPM7) expression and currents, which could contribute to neurotoxicity and cell death. Accordingly, suppression of TRPM7 reduces neuronal death, tissue damage and motor deficits. However, the neuroprotective effects of TRPM7 suppression in different cell types have not been investigated. Here, we found that induction of ischemia resulted in loss of parvalbumin (PV) gamma-aminobutyric acid (GABAergic) neurons more than Ca²⁺/calmodulin-kinase II (CaMKII) glutamatergic neurons in the mouse cortex. Furthermore, brain ischemia increased TRPM7 expression in PV neurons more than that in CaMKII neurons. We generated two lines of conditional knockout mice of TRPM7 in GABAergic PV neurons (PV-TRPM7^−/−) and in glutamatergic neurons (CaMKII-TRPM7^−/−). Following exposure to brain ischemia, we found that deleting TRPM7 reduced the infarct volume in both lines of transgenic mice. However, the volume in PV-TRPM7^−/− mice was more significantly lower than that in the control group. Neuronal survival of both GABAergic and glutamatergic neurons was increased in PV-TRPM7^−/− mice; meanwhile, only glutamatergic neurons were protected in CaMKII-TRPM7^−/−. At the behavioral level, only PV-TRPM7^−/− mice exhibited significant reductions in neurological and motor deficits. Inflammatory mediators such as GFAP, Iba1 and TNF-α were suppressed in PV-TRPM7^−/− more than in CaMKII-TRPM7^−/−. Mechanistically, p53 and cleaved caspase-3 were reduced in both groups, but the reduction in PV-TRPM7^−/− mice was more than that in CaMKII-TRPM7^−/− following ischemia. Upstream from these signaling molecules, the Akt anti-oxidative stress signaling was activated only in PV-TRPM7^−/− mice. Therefore, deleting TRPM7 in GABAergic PV neurons might have stronger neuroprotective effects against ischemia pathologies than doing so in glutamatergic neurons.

Maresin 1 promotes nerve regeneration and alleviates neuropathic pain after nerve injury

Background

Peripheral nerve injury (PNI) is a public health concern that results in sensory and motor disorders as well as neuropathic pain and secondary lesions. Currently, effective treatments for PNI are still limited. For example, while nerve growth factor (NGF) is widely used in the treatment of PNI to promote nerve regeneration, it also induces pain. Maresin 1 (MaR1) is an anti-inflammatory and proresolving mediator that has the potential to regenerate tissue. We determined whether MaR1 is able to promote nerve regeneration as well as alleviating neuropathic pain, and to be considered as a putative therapeutic agent for treating PNI.

Methods

PNI models were constructed with 8-week-old adult male ICR mice and treated with NGF, MaR1 or saline by local application, intrathecal injection or intraplantar injection. Behavioral analysis and muscle atrophy test were assessed after treatment. Immunofluorescence assay was performed to examine the expression of ATF-3, GFAP, IBA1, and NF200. The expression transcript levels of inflammatory factors IL1β, IL-6, and TNF-α were detected by quantitative real-time RT-PCR. AKT, ERK, mTOR, PI3K, phosphorylated AKT, phosphorylated ERK, phosphorylated mTOR, and phosphorylated PI3K levels were examined by western blot analysis. Whole-cell patch-clamp recordings were executed to detect transient receptor potential vanilloid 1 (TRPV1) currents.

Results

MaR1 demonstrated a more robust ability to promote sensory and motor function recovery in mice after sciatic nerve crush injury than NGF. Immunohistochemistry analyses showed that the administration of MaR1 to mice with nerve crush injury reduced the number of damaged DRG neurons, promoted injured nerve regeneration and inhibited gastrocnemius muscle atrophy. Western blot analysis of ND7/23 cells cultured with MaR1 or DRG neurons collected from MaR1 treated mice revealed that MaR1 regulated neurite outgrowth through the PI3K–AKT–mTOR signaling pathway. Moreover, MaR1 dose-dependently attenuated the mechanical allodynia and thermal hyperalgesia induced by nerve injury. Consistent with the analgesic effect, MaR1 inhibited capsaicin-elicited TRPV1 currents, repressed the nerve injury-induced activation of spinal microglia and astrocytes and reduced the production of proinflammatory cytokines in the spinal cord dorsal horn in PNI mice.

Conclusions

Application of MaR1 to PNI mice significantly promoted nerve regeneration and alleviated neuropathic pain, suggesting that MaR1 is a promising therapeutic agent for PNI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02405-1.

Maresin-1 and Inflammatory Disease

Inflammation is an essential action to protect the host human body from external, harmful antigens and microorganisms. However, an excessive inflammation reaction sometimes exceeds tissue damage and can disrupt organ functions. Therefore, anti-inflammatory action and resolution mechanisms need to be clarified. Dietary foods are an essential daily lifestyle that influences various human physiological processes and pathological conditions. Especially, omega-3 fatty acids in the diet ameliorate chronic inflammatory skin diseases. Recent studies have identified that omega-3 fatty acid derivatives, such as the resolvin series, showed strong anti-inflammatory actions in various inflammatory diseases. Maresin-1 is a derivative of one of the representative omega-3 fatty acids, i.e., docosahexaenoic acid (DHA), and has shown beneficial action in inflammatory disease models. In this review, we summarize the detailed actions of maresin-1 in immune cells and inflammatory diseases.

Advances in the Relationship Between Pyroptosis and Diabetic Neuropathy

Pyroptosis is a novel programmed cell death process that promotes the release of interleukin-1β (IL-1β) and interleukin-18 (IL-18) by activating inflammasomes and gasdermin D (GSDMD), leading to cell swelling and rupture. Pyroptosis is involved in the regulation of the occurrence and development of cardiovascular and cerebrovascular diseases, tumors, and nerve injury. Diabetes is a metabolic disorder characterized by long-term hyperglycemia, insulin resistance, and chronic inflammation. The people have paid more and more attention to the relationship between pyroptosis, diabetes, and its complications, especially its important regulatory significance in diabetic neurological diseases, such as diabetic encephalopathy (DE) and diabetic peripheral neuropathy (DPN). This article will give an in-depth overview of the relationship between pyroptosis, diabetes, and its related neuropathy, and discuss the regulatory pathway and significance of pyroptosis in diabetes-associated neuropathy.

Matrix stiffness regulates bone repair by modulating 12-lipoxygenase-mediated early inflammation

Lipid metabolism in macrophages has been increasingly emphasized in exerting an anti-inflammatory effect and accelerating fracture healing. 12-lipoxygenase (12-LOX) is expressed in several cell types, including macrophages, and oxidizes polyunsaturated fatty acids (PUFAs) to generate both pro- and anti-inflammatory lipid mediators, of which the n-3 PUFAs play an important part in tissue homeostasis/fibrosis. Although mechanical factor regulates the lipid metabolic axis of inflammatory cells, specifically matrix stiffness influences macrophages metabolic responses, little is known about how matrix stiffness affects the 12-LOX-mediated early inflammation in bone repair. In the present study, demineralized bone matrix (DBM) scaffolds with different matrix stiffness were constructed by controlling the duration of decalcification (0 h (control), 1 h (high), 12 h (medium), and 5 d (low)) to repair the defected rat skull. The expression of inflammatory cytokines and macrophages polarization were analyzed. The lipid metabolites and lipid mediators' biosynthesis by matrix stiffness-regulated were further detected. The results showed that the low matrix stiffness could polarize macrophages into an anti-inflammatory phenotype, promote the expression of anti-inflammatory cytokines and specialized pro-resolving lipid mediators (SPMs) biosynthesis beneficial for the osteogenesis of mesenchymal stem cells (MSCs). After treated with ML355, the expression of anti-inflammatory cytokines/proteins and SPMs biosynthesis in macrophages cultured on low-matrix stiffness scaffolds were repressed, and there were almost no statistical differences among all groups. Findings from this study support that matrix stiffness regulates bone repair by modulating 12-LOX-mediated early inflammation, which suggest a direct mechanical impact of matrix stiffness on macrophages lipid metabolism and provide a new insight into the clinical application of SPMs for bone regeneration.

Inflammation and tumor progression: signaling pathways and targeted intervention

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

Metabolomics and metabolites in ischemic stroke

Stroke is a major reason for disability and the second highest cause of death in the world. When a patient is admitted to a hospital, it is necessary to identify the type of stroke, and the likelihood for development of a recurrent stroke, vascular dementia, and depression. These factors could be determined using different biomarkers. Metabolomics is a very promising strategy for identification of biomarkers. The advantage of metabolomics, in contrast to other analytical techniques, resides in providing low molecular weight metabolite profiles, rather than individual molecule profiles. Technically, this approach is based on mass spectrometry and nuclear magnetic resonance. Furthermore, variations in metabolite concentrations during brain ischemia could alter the principal neuronal functions. Different markers associated with ischemic stroke in the brain have been identified including those contributing to risk, acute onset, and severity of this pathology. In the brain, experimental studies using the ischemia/reperfusion model (IRI) have shown an impaired energy and amino acid metabolism and confirmed their principal roles. Literature data provide a good basis for identifying markers of ischemic stroke and hemorrhagic stroke and understanding metabolic mechanisms of these diseases. This opens an avenue for the successful use of identified markers along with metabolomics technologies to develop fast and reliable diagnostic tools for ischemic and hemorrhagic stroke.

The role of lipid-based signalling in wound healing and senescence

Lipid-based signalling modulates several cellular processes and intercellular communication during wound healing and tissue regeneration. Bioactive lipids include but are not limited to the diverse group of eicosanoids, phospholipids, and extracellular vesicles and mediate the attraction of immune cells, initiation of inflammatory responses, and their resolution. In aged individuals, wound healing and tissue regeneration are greatly impaired, resulting in a delayed healing process and non-healing wounds. Senescent cells accumulate with age in vivo, preferably at sites implicated in age-associated pathologies and their elimination was shown to alleviate many age-associated diseases and disorders. In contrast to these findings, the transient presence of senescent cells in the process of wound healing exerts beneficial effects and limits fibrosis. Hence, clearance of senescent cells during wound healing was repeatedly shown to delay wound closure in vivo. Recent findings established a dysregulated synthesis of eicosanoids, phospholipids and extracellular vesicles as part of the senescent phenotype. This intriguing connection between cellular senescence, lipid-based signalling, and the process of wound healing and tissue regeneration prompts us to compile the current knowledge in this review and propose future directions for investigation.

Bioactive Lipid Mediators in the Initiation and Resolution of Inflammation after Spinal Cord Injury

Neuroinflammation is a prominent feature of the response to CNS trauma. It is also an important hallmark of various neurodegenerative diseases in which inflammation contributes to the progression of pathology. Inflammation in the CNS can contribute to secondary damage and is therefore an excellent therapeutic target for a range of neurological conditions. Inflammation in the nervous system is complex and varies in its fine details in different conditions. It involves a wide variety of secreted factors such as chemokines and cytokines, cell adhesion molecules, and different cell types that include resident cell of the CNS, as well as immune cells recruited from the peripheral circulation. Added to this complexity is the fact that some aspects of inflammation are beneficial, while other aspects can induce secondary damage in the acute, subacute and chronic phases. Understanding these aspects of the inflammatory profile is essential for developing effective therapies. Bioactive lipids constitute a large group of molecules that modulate the initiation and the resolution of inflammation. Dysregulation of these bioactive lipid pathways can lead to excessive acute inflammation, and failure to resolve this by specialized pro-resolution lipid mediators can lead to the development of chronic inflammation. The focus of this review is to discuss the effects of bioactive lipids in spinal cord trauma and their potential for therapies.

Fish Hydrolysate Supplementation Containing n-3 Long Chain Polyunsaturated Fatty Acids and Peptides Prevents LPS-Induced Neuroinflammation

Neuroinflammation constitutes a normal part of the brain immune response orchestrated by microglial cells. However, a sustained and uncontrolled production of proinflammatory factors together with microglial activation contribute to the onset of a chronic low-grade inflammation, leading to neuronal damage and cognitive as well as behavioral impairments. Hence, limiting brain inflammatory response and improving the resolution of inflammation could be particularly of interest to prevent these alterations. Dietary n-3 long chain polyunsaturated fatty acids (LC-PUFAs) and low molecular weight peptides are good candidates because of their immunomodulatory and proresolutive properties. These compounds are present in a fish hydrolysate derived from marine-derived byproducts. In this study, we compared the effect of an 18-day supplementation with this fish hydrolysate to a supplementation with docosahexaenoic acid (DHA) on lipopolysaccharide (LPS)-induced inflammation in mice. In response to peripherally injected LPS, the fish hydrolysate supplementation decreased the hippocampal mRNA expression of the proinflammatory cytokines IL-6 (p < 0.001), IL-1β (p = 0.0008) and TNF-α (p < 0.0001), whereas the DHA supplementation reduced only the expression of IL-6 (p = 0.004). This decline in proinflammatory cytokine expressions was associated with an increase in the protein expression of IκB (p = 0.014 and p = 0.0054 as compared to the DHA supplementation and control groups, respectively) and to a modulation of microglial activation markers in the hippocampus. The beneficial effects of the fish hydrolysate could be due in part to the switch of the hippocampal oxylipin profile towards a more anti-inflammatory profile as compared to the DHA supplementation. Thus, the valorization of fish byproducts seems very attractive to prevent and counteract neuroinflammation.

MAR1 suppresses inflammatory response in LPS-induced RAW 264.7 macrophages and human primary peripheral blood mononuclear cells via the SIRT1/PGC-1α/PPAR-γ pathway

Background

Sepsis is a complex syndrome characterized by a dysregulated inflammatory response to systemic infection and leads to shock, multiple organ failure and death especially if not recognized early and treated promptly. Previous studies have suggested Maresin 1 (MAR1) can alleviate systemic inflammation in sepsis, but its mechanism has not been clarified.

Methods

RAW 264.7 cells and human primary peripheral blood mononuclear cells (hPBMCs) were pretreated with LPS and MAR1. The mRNA expression and supernatant levels of pro-inflammatory cytokines, tumor necrosis factor (TNF-α), interleukin (IL)-1β and IL-6 were evaluated by RT-qPCR and ELISA, respectively. The expression levels of Sirtuin 1 (SIRT1), peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), and Peroxisome proliferator-activated receptor gamma (PPAR-γ) were determined by RT-qPCR and Western blot analysis, respectively.

Results

Our results show that LPS-induced inflammation increased the expression and secretion of proinflammatory cytokines TNF-α, IL-1β and IL-6 and induced suppression of SIRT1, PGC-1α, and PPAR-γ expression, which could be reversed by MAR1. And the effect of MAR1 was eliminated by repression of SIRT1/PPAR-γ and enhanced by PGC-1α overexpression.

Conclusions

MAR1 suppressed inflammatory response in LPS-induced RAW 264.7 macrophages and hPBMCs via the SIRT1/PGC-1α/PPAR-γ pathway.

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

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

Maresin 1 attenuates pro-inflammatory activation induced by β-amyloid and stimulates its uptake

Alzheimer's disease (AD) is the most common dementia, characterized by pathological accumulation of β‐amyloid (Aβ) and hyperphosphorylation of tau protein, together with a damaging chronic inflammation. The lack of effective treatments urgently warrants new therapeutic strategies. Resolution of inflammation, associated with beneficial and regenerative activities, is mediated by specialized pro‐resolving lipid mediators (SPMs) including maresin 1 (MaR1). Decreased levels of MaR1 have been observed in AD brains. However, the pro‐resolving role of MaR1 in AD has not been fully investigated. In the present study, human monocyte‐derived microglia (MdM) and a differentiated human monocyte cell line (THP‐1 cells) exposed to Aβ were used as models of AD neuroinflammation. We have studied the potential of MaR1 to inhibit pro‐inflammatory activation of Aβ and assessed its ability to stimulate phagocytosis of Aβ₄₂. MaR1 inhibited the Aβ₄₂‐induced increase in cytokine secretion and stimulated the uptake of Aβ₄₂ in both MdM and differentiated THP‐1 cells. MaR1 was also found to decrease chemokine secretion and reduce the associated increase in the activation marker CD40. Activation of kinases involved in transduction of inflammation was not affected by MaR1, but the activity of nuclear factor (NF)‐κB was decreased. Our data show that MaR1 exerts effects that indicate a pro‐resolving role in the context of AD and thus presents itself as a potential therapeutic target for AD.

Novel Approaches for Omega-3 Fatty Acid Therapeutics: Chronic Versus Acute Administration to Protect Heart, Brain, and Spinal Cord

This article reviews novel approaches for omega-3 fatty acid (FA) therapeutics and the linked molecular mechanisms in cardiovascular and central nervous system (CNS) diseases. In vitro and in vivo research studies indicate that omega-3 FAs affect synergic mechanisms that include modulation of cell membrane fluidity, regulation of intracellular signaling pathways, and production of bioactive mediators. We compare how chronic and acute treatments with omega-3 FAs differentially trigger pathways of protection in heart, brain, and spinal cord injuries. We also summarize recent omega-3 FA randomized clinical trials and meta-analyses and discuss possible reasons for controversial results, with suggestions on improving the study design for future clinical trials. Acute treatment with omega-3 FAs offers a novel approach for preserving cardiac and neurological functions, and the combinations of acute treatment with chronic administration of omega-3 FAs might represent an additional therapeutic strategy for ameliorating adverse cardiovascular and CNS outcomes.

Maresin1 Promotes M2 Macrophage Polarization Through Peroxisome Proliferator-Activated Receptor-γ Activation to Expedite Resolution of Acute Lung Injury

BACKGROUND

Acute lung injury (ALI), manifested by progressive hypoxemia and respiratory distress, is associated with high morbidity and mortality, which lacks the effective therapies in clinics. Our previous studies demonstrated that maresin1 (MaR1), a specialized proresolving mediator, could effectively mitigate the inflammation of lipopolysaccharide (LPS)-induced ALI. However, whether MaR1 impacts the macrophage polarization to alleviate ALI remains unclear. Our study explored the effects and underlying mechanisms of MaR1 on the macrophage phenotypes in ALI.

MATERIAL AND METHODS

Male BALB/c mice were subjected to endotracheal instillation of LPS to induce ALI and then intravenously injected with MaR1 or normal saline. Intraperitoneal administration of peroxisome proliferator-activated receptor-γ (PPAR-γ) inhibitor GW9662 was given 30 mins before MaR1. We measured the pathohistologic changes, pulmonary edema, inflammatory cytokines, and the flow cytometry of macrophage phenotypes.

RESULTS

Our results illustrated that MaR1 ameliorated lung injury and increased monocyte or macrophage recruitment and the release of anti-inflammatory cytokines. The flow cytometry showed that MaR1 promoted polarization of CD11c^-CD206⁺ (M2) macrophages and inhibited polarization of CD11c⁺CD206^- (M1) macrophages. Besides, the western blotting revealed that MaR1 increased the expression of PPAR-γ. The pretreatment with PPAR-γ antagonist GW9662 could significantly suppress the polarization of M2 macrophages and antagonize the protective effects of MaR1 on LPS-stimulated ALI.

CONCLUSIONS

MaR1 was able to promote M2 macrophage polarization by reversing LPS-mediated PPAR-γ inhibition, thereby expediting the recovery of LPS-stimulated ALI.

Specialized pro-resolving lipid mediators in cardiovascular disease, diagnosis, and therapy

Persistent inflammation is the key aggravator in many cardiovascular diseases, including atherosclerosis, aneurysm, injury/reperfusion, thrombosis, and neointimal hyperplasia following surgical or percutaneous interventions. Resolution is an active process orchestrated by specialized pro-resolving lipid mediators (SPMs) which tamp down acute inflammatory signals, promote healing and facilitate a return to homeostasis. SPMs are endogenously derived from poly-unsaturated fatty acids, and their biologic activity is mediated via specific G-protein coupled receptor binding. The potency of SPM in regulating the inflammatory response has encouraged investigation into their therapeutic and diagnostic use in cardiovascular pathologies. Herein we describe the translational groundwork which has established the synthesis and interactions of SPM in cardiovascular and hematologic cells, the therapeutic effects of SPM in animal models of cardiovascular disease, and some early technologies that harness and attempt to optimize SPM delivery and "resolution pharmacology". Further studies are required to precisely determine the mechanisms of resolution in the cardiovascular system and to determine the clinical settings in which SPM can be utilized to optimize patient outcomes.

Neuroprotective effect of Umbelliferone against Cerebral ischemia/Reperfusion induced neurological deficits: in-vivo and in-silico studies

Inflammatory pathway is the significant marker of neuro-inflammation and plays a significant role in the expansion of cerebral ischemia/reperfusion injury. Umbelliferone (UF), 7-hydroxy coumarin, has been already proved for its anti-inflammatory and anti-oxidative effects against ischemic brain injury in the rodent model, but its underlying pharmacological mechanism for neuro-protection remain unclear. In this study, we try to explore the neuro-protective effect of umbelliferone against ischemia/Reperfusion induced neurological deficits in rats and explore the underlying mechanism. Inserting thread into the middle cerebral artery was used to induce the ischemic stroke model. The rats were treated with the umbelliferone (5, 10 and 20 mg/kg) for 14 days prior to the ischemic stroke. At the end of the experimental study, brain infarction volume, neurological score, brain edema, pro-inflammatory cytokines, inflammatory mediator were estimated in the region of brain and serum. The mRNA expression of Toll-like receptor-4 (TLR4), myeloid differentiation factor 88 (MyD88), Fas and FasL were also estimated at the end of the study. Dose dependently treatment of umbelliferone down-regulated the neurological score, brain infarction, inflammatory mediator (TNF-α, IL-1β, IL-6, COX-2, NF-kB and PGE₂) in the serum and brain tissue as compared to I/R induced control group rats. Umbelliferone also reduced the expression of TRL4, MyD88, Fas and FasL as compared to I/R control group rats. Umbelliferone also decreased the level of nuclear factor kappa B (NF-kB) compared to MACO control group rats. Collectively, the obtained result showed that the umbelliferone protected the brain against the ischemic injury in the rats through the inhibition of inflammatory pathway.Communicated by Ramaswamy H. Sarma.

Lipid mediators and sterile inflammation in ischemic stroke

Stroke is one of the major causes of lethality and disability, yet few effective therapies have been established for ischemic stroke. Inflammation in the ischemic brain is induced by the infiltration and subsequent activation of immune cells. Loss of cerebral blood flow and ischemic brain-cell death trigger the activation of infiltrating immune cells and drastic changes in the lipid content of the ischemic brain. In particular, polyunsaturated fatty acids and their metabolites regulate cerebral post-ischemic inflammation and ischemic stroke pathologies. In this review, we discuss the relationships between the lipid mediators and cerebral post-ischemic inflammation and their relevance to possible future therapeutic strategies targeting lipid mediators for ischemic stroke.

The Anti-Inflammatory Role of Omega-3 Polyunsaturated Fatty Acids Metabolites in Pre-Clinical Models of Psychiatric, Neurodegenerative, and Neurological Disorders

Inflammation has been identified as one of the main pathophysiological mechanisms underlying neuropsychiatric and neurodegenerative disorders. Despite the role of inflammation in those conditions, there is still a lack of effective anti-inflammatory therapeutic strategies. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) can reduce depressive symptoms and exert anti-inflammatory action putatively by the production of distinct n-3 PUFA-derived metabolites, such as resolvins D (RvD) and E (RvE) series, maresins (MaR) and protectins (PD), which are collectively named specialized pro-resolving mediators (SPMs) and act as strong anti-inflammatory agents. In this review we summarize evidence showing the effects of treatment with those metabolites in pre-clinical models of psychiatric, neurodegenerative and neurological disorders. A total of 25 pre-clinical studies were identified using the PubMed database. Overall, RvD and RvE treatment improved depressive-like behaviors, whereas protectins and maresins ameliorated neurological function. On a cellular level, RvDs increased serotonin levels in a model of depression, and decreased gliosis in neurodegenerative disorders. Protectins prevented neurite and dendrite retraction and apoptosis in models of neurodegeneration, while maresins reduced cell death across all studies. In terms of mechanisms, all SPMs down-regulated pro-inflammatory cytokines. Resolvins activated mTOR and MAP/ERK signaling in models of depression, while resolvins and maresins activated the NF-κB pathway in models of neurodegeneration and neurological disorders. Our review indicates a potential promising approach for tailored therapy with n-3 PUFAs-derived metabolites in the treatment of psychiatric, neurodegenerative, and neurological conditions.

n-3 Polyunsaturated Fatty Acids and Their Derivates Reduce Neuroinflammation during Aging

: Aging is associated to cognitive decline, which can lead to loss of life quality, personal suffering, and ultimately neurodegenerative diseases. Neuroinflammation is one of the mechanisms explaining the loss of cognitive functions. Indeed, aging is associated to the activation of inflammatory signaling pathways, which can be targeted by specific nutrients with anti-inflammatory effects. Dietary n-3 polyunsaturated fatty acids (PUFAs) are particularly attractive as they are present in the brain, possess immunomodulatory properties, and are precursors of lipid derivates named specialized pro-resolving mediators (SPM). SPMs are crucially involved in the resolution of inflammation that is modified during aging, resulting in chronic inflammation. In this review, we first examine the effect of aging on neuroinflammation and then evaluate the potential beneficial effect of n-3 PUFA as precursors of bioactive derivates, particularly during aging, on the resolution of inflammation. Lastly, we highlight evidence supporting a role of n-3 PUFA during aging.

Inflammation resolution and specialized pro-resolving lipid mediators in CNS diseases

Introduction: Inflammation resolution induced by specialized pro-resolving lipid mediators (SPMs) is a new concept. The application of SPMs is a promising therapeutic strategy that can potentially supersede anti-inflammatory drugs. Most CNS diseases are associated with hyperreactive inflammatory damage. CNS inflammation causes irreversible neuronal loss and permanent functional impairments. Given the high mortality and morbidity rates, the investigation of therapeutic strategies to ameliorate inflammatory damage is necessary.Areas covered: In this review, we explore inflammation resolution in CNS disorders. We discuss the underlying mechanisms and dynamic changes of SPMs and their precursors in neurological diseases and examine how this can potentially be incorporated into the clinic. References were selected from PubMed; most were published between 2010 and 2019.Expert opinion: Inflammation resolution is a natural process that emerges after acute or chronic inflammation. The evidence that SPMs can effectively ameliorate hyperreactive inflammation, shorten resolution time and accelerate tissue regeneration in CNS disorders. Adjuvants and nanotechnology offer opportunities for SPM drug design; however, more preclinical studies are necessary to investigate basic, critical issues such as safety.

N-3 Polyunsaturated Fatty Acids and the Resolution of Neuroinflammation

In the past few decades, as a result of their anti-inflammatory properties, n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFAs), have gained greater importance in the regulation of inflammation, especially in the central nervous system (in this case known as neuroinflammation). If sustained, neuroinflammation is a common denominator of neurological disorders, including Alzheimer’s disease and major depression, and of aging. Hence, limiting neuroinflammation is a real strategy for neuroinflammatory disease therapy and treatment. Recent data show that n-3 LC-PUFAs exert anti-inflammatory properties in part through the synthesis of specialized pro-resolving mediators (SPMs) such as resolvins, maresins and protectins. These SPMs are crucially involved in the resolution of inflammation. They could be good candidates to resolve brain inflammation and to contribute to neuroprotective functions and could lead to novel therapeutics for brain inflammatory diseases. This review presents an overview 1) of brain n-3 LC-PUFAs as precursors of SPMs with an emphasis on the effect of n-3 PUFAs on neuroinflammation, 2) of the formation and action of SPMs in the brain and their biological roles, and the possible regulation of their synthesis by environmental factors such as inflammation and nutrition and, in particular, PUFA consumption.

Protective effects of maresin 1 against inflammation in experimentally induced acute pancreatitis and related lung injury

Severe acute pancreatitis (SAP) is an inflammatory disorder that progresses with local and systemic difficulties accompanied by a relatively high mortality rate. In recent years, maresin 1 (MaR1) has been shown to be a macrophage mediator with effective proresolving and anti-inflammatory properties that prevents the occurrence of various inflammatory conditions. The purpose of this study was to investigate the role of MaR1 in SAP and related lung injury. Experimental SAP was induced in mice with a combination of cerulean and lipopolysaccharide. MaR1 was administered 30 min before the primary injection of cerulean. Biochemical markers and histological injury scores were used to evaluate the severity of acute pancreatitis. To determine the degree of inflammation, serum cytokines and myeloperoxidase activity in pancreas and lung tissues were measured. Western blot analysis detected the activation of NF-κB. After MaR1 pretreatment, the activities of amylase, lipase, TNF-α, IL-1β, and IL-6 were decreased in serum, and the myeloperoxidase activity both in pancreas and in lung tissues significantly decreased, whereas the activity of anti-inflammatory cytokine IL-10 in serum was increased. MaR1-pretreated mice reduced the activation of pancreatic NF-κB and decreased the severity of pancreatic and lung-related injuries. These results confirm that MaR1 alleviated inflammation of the pancreas and lung by inhibiting the activity of NF-κB in experimentally induced acute pancreatitis and exerted anti-inflammatory effects. These findings suggest that MaR1 could be a new and useful drug in the treatment of SAP.NEW & NOTEWORTHY These results provided us evidence to confirm that maresin 1 (MaR1) can alleviate inflammation of the pancreas and lung by inhibiting the activity of NF-κB in experimental induced acute pancreatitis and exerts certain anti-inflammatory effects. These findings suggest that MaR1 could be a new and useful drug in the treatment of severe acute pancreatitis.

A NMR-Based Metabonomics Approach to Determine Protective Effect of a Combination of Multiple Components Derived from Naodesheng on Ischemic Stroke Rats

Naodesheng (NDS) is a widely used traditional Chinese medicine (TCM) prescription for the treatment of ischemic stroke. A combination of 10 components is derived from NDS. They are: Notoginsenoside R1, ginsenoside Rg1, ginsenoside b1, ginsenoside Rd, hydroxysafflor yellow A, senkyunolide I, puerarin, daidzein, vitexin, and ferulic acid. This study aimed to investigate the protective effect of the ten-component combination derived from NDS (TCNDS) on ischemic stroke rats with a middle cerebral artery occlusion (MCAO) model by integrating an NMR-based metabonomics approach with biochemical assessment. Our results showed that TCNDS could improve neurobehavioral function, decrease the cerebral infarct area, and ameliorate pathological features in MCAO model rats. In addition, TCNDS was found to decrease plasma lactate dehydrogenase (LDH) and malondialdehyde (MDA) production and increase plasma superoxide dismutase (SOD) production. Furthermore, ¹H-NMR metabonomic analysis indicated that TCNDS could regulate the disturbed metabolites in the plasma, urine, and brain tissue of MCAO rats, and the possible mechanisms were involved oxidative stress, energy metabolism, lipid metabolism, amino acid metabolism, and inflammation. Correlation analysis were then performed to further confirm the metabolites involved in oxidative stress. Correlation analysis showed that six plasma metabolites had high correlations with plasma LDH, MDA, and SOD. This study provides evidence that an NMR-based metabonomics approach integrated with biochemical assessment can help to better understand the underlying mechanisms as well as the holistic effect of multiple compounds from TCM.

Inflammation and pericarditis: Are neutrophils actors behind the scenes?

The morbidity of acute pericarditis is increasing over time impacting on patient quality of life. Recent clinical trials focused especially on clinical aspects, with a modest interest in pathophysiological mechanisms. This narrative review, based on papers in English language obtained via PubMed up to April 2018, aims at focusing on the role of the innate immunity in pericarditis and discussing future potential therapeutic strategies impacting on disease pathophysiology. In developed countries, most cases of pericarditis are referred to as idiopathic, although etiological causes have been described, with autoreactive/lymphocytic, malignant, and infectious ones as the most frequent causes. Apart the known impairment of the adaptive immunity, recently a large body evidence indicated the central role of the innate immune system in the pathogenesis of recurrent pericarditis, starting from similarities with autoinflammatory diseases. Accordingly, the "inflammasome" has been shown to behave as an important player in pericarditis development. Similarly, the beneficial effect of colchicine in recurrent pericarditis confirms that neutrophils are important effectors as colchicine, which can block neutrophil chemotaxis, interferes with neutrophil adhesion and recruitment to injured tissues and abrogate superoxide production. Anyway, the role of the adaptive immune system in pericarditis cannot be reduced to a black or white issue as mechanisms often overlap. Therefore, we believe that more efficient therapeutic strategies have to be investigated by targeting neutrophil-derived mediators (such as metalloproteinases) and disentangling the strict interplay between neutrophils and platelets. In this view, some progress has been done by using the recombinant human interleukin-1 receptor antagonist anakinra.

Pro-resolving lipid mediators in vascular disease

Unresolved inflammation is central to the pathophysiology of commonly occurring vascular diseases such as atherosclerosis, aneurysm, and deep vein thrombosis - conditions that are responsible for considerable morbidity and mortality. Surgical or catheter-based procedures performed on affected blood vessels induce acute-on-chronic inflammatory responses. The resolution of vascular inflammation is an important driver of vessel wall remodeling and functional recovery in these clinical settings. Specialized pro-resolving lipid mediators (SPMs) derived from omega-3 polyunsaturated fatty acids orchestrate key cellular processes driving resolution and a return to homeostasis. The identification of their potent effects in classic animal models of sterile inflammation triggered interest in their vascular properties. Recent studies have demonstrated that SPMs are locally synthesized in vascular tissues, have direct effects on vascular cells and their interactions with leukocytes, and play a protective role in the injury response. Early translational work has established the potential for SPMs as vascular therapeutics, and as candidate biomarkers in vascular disease. Further investigations are needed to understand the molecular and cellular mechanisms of resolution in the vasculature, to improve tools for clinical measurement, and to better define the potential for "resolution therapeutics" in vascular patients.

Pro-resolving mediator maresin 1 ameliorates pain hypersensitivity in a rat spinal nerve ligation model of neuropathic pain

Background

Pro-resolving mediators (PRMs) are considered as emerging analgesics for chronic pain. Maresin 1 (MaR1) is a newly identified member of PRMs, and recent studies implicate its potential role in some pain conditions. As the function of MaR1 in neuropathic pain remains unclear, we investigated the effects of MaR1 on pain hypersensitivity and the underlying mechanism using a rat spinal nerve ligation (SNL) model of neuropathic pain.

Materials and methods

MaR1 (100 ng/10 μL) or commensurable artificial cerebrospinal fluid was delivered via intrathecal catheter from days 3 to 5 post-SNL followed by assessment of mechanical allodynia and thermal hyperalgesia. Ipsilateral L4–L5 spinal cord tissue was collected on day 7 post-SNL and assessed by Western blotting, enzyme-linked immunosorbent assay or immunohistochemistry.

Results

Intrathecal MaR1 significantly attenuated mechanical allodynia and thermal hyperalgesia from day 5 to day 7 post-SNL, which was associated with decreased spinal levels of glial markers, GFAP and IBA1. It was also found that intrathecal MaR1 downregulated phosphorylation levels of NF-κB p65 and its nuclear translocation, as well as decreased protein levels of pro-inflammatory cytokines, TNF-α, IL-1β and IL-6. Further, MaR1 treatment restored PSD95 and synapsin II levels, suggesting that MarR1 also protected synaptic integrity.

Conclusion

Our results indicate that MaR1 ameliorates the SNL-induced neuropathic pain by regulating glial activities and pro-inflammatory cytokines release. The present study offers insight into the potential of MaR1 as a novel intervention to ameliorate neuropathic pain.

Roles of Specialized Pro-Resolving Lipid Mediators in Cerebral Ischemia Reperfusion Injury

Ischemic stroke contributes to ~80% of all stroke cases. Recanalization with thrombolysis or endovascular thrombectomy are currently critical therapeutic strategies for rebuilding the blood supply following ischemic stroke. However, recanalization is often accompanied by cerebral ischemia reperfusion injury that is mediated by oxidative stress and inflammation. Resolution of inflammation belongs to the end stage of inflammation where inflammation is terminated and the repair of damaged tissue is started. Resolution of inflammation is mediated by a group of newly discovered lipid mediators called specialized pro-resolving lipid mediators (SPMs). Accumulating evidence suggests that SPMs decrease leukocyte infiltration, enhance efferocytosis, reduce local neuronal injury, and decrease both oxidative stress and the production of inflammatory cytokines in various in vitro and in vivo models of ischemic stroke. In this review, we summarize the mechanisms of reperfusion injury and the various roles of SPMs in stroke therapy.

Death-associated protein kinase 1 mediates interleukin-1β production through regulating inlfammasome activation in Bv2 microglial cells and mice

Interleukin-1β (IL-1β) plays a crucial role in mediating inflammation and innate immunity response in the central nervous system. Death-associated protein kinase 1 (DAPK1) was shown to be involved in several cellular processes. Here, we investigated the effects of DAPK1 on IL-1β production in microglial cells. We used a combination of in vitro (Bv2 microglial cell cultures) and in vivo (mice injected with amyloid-β (Aβ)) techniques to address the role of caspase-1 activation in release of IL-1β. DAPK1 involvement was postulated through genetic approaches and pharmacological blockade of this enzyme. We found that Aβ_25-35 stimulation induced IL-1β production and caspase-1 activation in LPS-primed Bv2 cells and mice. DAPK1 knockdown and catalytic activity inhibition reduced IL-1β maturation and caspase-1 activation, nevertheless, DAPK1 overexpression attenuated these effects. Aβ_25-35-induced lysosomal cathepsin B leakage was required for DAPK1 activation. Furthermore, repeated DAPK1 inhibitor treatment ameliorated the memory impairment in Aβ_25-35-injected mice. Taken together, our findings suggest that DAPK1 facilitates Aβ_25-35-induced IL-1β production through regulating caspase-1 activation in microglial cells.

Changes in the hippocampal and peripheral phospholipid profiles are associated with neurodegeneration hallmarks in a long-term global cerebral ischemia model: Attenuation by Linalool

Phospholipid alterations in the brain are associated with progressive neurodegeneration and cognitive impairment after acute and chronic injuries. Various types of treatments have been evaluated for their abilities to block the progression of the impairment, but effective treatments targeting long-term post-stroke alterations are not available. In this study, we analyzed changes in the central and peripheral phospholipid profiles in ischemic rats and determined whether a protective monoterpene, Linalool, could modify them. We used an in vitro model of glutamate (125 μM) excitotoxicity and an in vivo global ischemia model in Wistar rats. Linalool (0.1 μM) protected neurons and astrocytes by reducing LDH release and restoring ATP levels. Linalool was administered orally at a dose of 25 mg/kg every 24 h for a month, behavioral tests were performed, and a lipidomic analysis was conducted using mass spectrometry. Animals treated with Linalool displayed faster neurological recovery than untreated ischemic animals, accompanied by better motor and cognitive performances. These results were confirmed by the significant reduction in astrogliosis, microgliosis and COX-2 marker, involving a decrease of 24:0 free fatty acid in the hippocampus. The altered profiles of phospholipids composed of mono and polyunsaturated fatty acids (PC 36:1; 42:1 (24:0/18:1)/LPC 22:6)/LPE 22:6) in the ischemic hippocampus and the upregulation of PI 36:2 and other LCFA (long chain fatty acids) in the serum of ischemic rats were prevented by the monoterpene. Based on these data, alterations in the central and peripheral phospholipid profiles after long-term was attenuated by oral Linalool, promoting a phospholipid homeostasis, related to the recovery of brain function.

Anti-Inflammatory Effects of Omega-3 Fatty Acids in the Brain: Physiological Mechanisms and Relevance to Pharmacology

Classically, polyunsaturated fatty acids (PUFA) were largely thought to be relatively inert structural components of brain, largely important for the formation of cellular membranes. Over the past 10 years, a host of bioactive lipid mediators that are enzymatically derived from arachidonic acid, the main n-6 PUFA, and docosahexaenoic acid, the main n-3 PUFA in the brain, known to regulate peripheral immune function, have been detected in the brain and shown to regulate microglia activation. Recent advances have focused on how PUFA regulate the molecular signaling of microglia, especially in the context of neuroinflammation and behavior. Several active drugs regulate brain lipid signaling and provide proof of concept for targeting the brain. Because brain lipid metabolism relies on a complex integration of diet, peripheral metabolism, including the liver and blood, which supply the brain with PUFAs that can be altered by genetics, sex, and aging, there are many pathways that can be disrupted, leading to altered brain lipid homeostasis. Brain lipid signaling pathways are altered in neurologic disorders and may be viable targets for the development of novel therapeutics. In this study, we discuss in particular how n-3 PUFAs and their metabolites regulate microglia phenotype and function to exert their anti-inflammatory and proresolving activities in the brain.

New monocyte locomotion inhibitory factor analogs protect against cerebral ischemia-reperfusion injury in rats

Monocyte locomotion inhibitory factor (MLIF) is an oligopeptide with anti-inflammatory properties. The carboxyl-terminal end group Cys-Asn-Ser serves as the pharmacophore of MLIF. The aim of this study was to investigate the neuroprotective effects of two new synthetic analogs, Arg-Cys-Asn-Ser and D-Cys-Asn-Ser, on focal cerebral ischemia, which were designed and synthesized to increase the penetrability and enzymatic stability of Cys-Asn-Ser. Ninety-one male Sprague-Dawley rats were randomly divided into six groups: I - Sham; II - Ischemia-reperfusion (I/R); III - Nimodipine; IV - Cys-Asn-Ser; V - D-Cys-Asn-Ser; and VI - Arg-Cys-Asn-Ser. The rats in groups II-VI were subjected to middle cerebral artery occlusion. After 24 hours of reperfusion, the neurological deficit, cerebral infarct volume, and levels of the pro-inflammatory factors interleukin-1β (IL-1β) and tumor necrosis factor-alpha in brain tissue homogenates were assessed. Compared with the sham group, the mean neurological deficit scores were significantly higher in groups II-VI (p ≤ 0.019 for all). The mean infarct volumes were significantly higher in I/R and Cys-Asn-Ser groups compared with the sham group (both p ≤ 0.046). The mean IL-1β level was significantly lower in D-Cys-Asn-Ser and Arg-Cys-Asn-Ser groups compared with I/R group (both p ≤ 0.046). In conclusion, the results showed that Arg-Cys-Asn-Ser and D-Cys-Asn-Ser have the potential for protective effects against focal cerebral ischemia injury.