Lipoxin A4-induced heme oxygenase-1 protects cardiomyocytes against hypoxia/reoxygenation injury via p38 MAPK activation and Nrf2/ARE complex

A signaling network map of Lipoxin (LXA4): an anti-inflammatory molecule

Lipoxins (LXs) are a class of endogenous bioactive lipid mediators that are involved in the regulation of inflammation. They exert immunomodulatory effects by regulating the behaviour of various immune cells, including neutrophils, macrophages, and T and B cells, by promoting the clearance of apoptotic neutrophils. This helps to dampen inflammation and promote tissue repair. LXs regulate the expression of many inflammatory genes by modulating the levels of transcription factors, such as nuclear factor κB (NF-κB), activator protein-1 (AP-1), nerve growth factor-regulated factor 1A binding protein 1 (NGF), and peroxisome proliferator activated receptor γ (PPAR-γ), which are elevated in various diseases, such as respiratory tract diseases, renal diseases, cancer, neurodegenerative diseases, and viral infections. Lipoxin-mediated signaling is involved in chronic inflammation, cancer, diabetes-associated kidney disease, lung injury, liver injury, endometriosis, respiratory tract diseases, neurodegenerative diseases, chronic cerebral hypoperfusion, and retinal degeneration. In this study, we systematically investigated the intricate network of lipoxin signaling by analyzing the relevant literature. The resulting map comprised 467 molecules categorized as activation/inhibition, enzyme catalysis, gene and protein expression, molecular associations, and translocation events. This map serves as a valuable resource for understanding the complexity of lipoxin signaling and its impact on various cellular functions.

Therapeutic activity of lipoxin A4 in TiO2-induced arthritis in mice: NF-κB and Nrf2 in synovial fluid leukocytes and neuronal TRPV1 mechanisms

Background

Lipoxin A4 (LXA4) has anti-inflammatory and pro-resolutive roles in inflammation. We evaluated the effects and mechanisms of action of LXA4 in titanium dioxide (TiO2) arthritis, a model of prosthesis-induced joint inflammation and pain.

Methods

Mice were stimulated with TiO2 (3mg) in the knee joint followed by LXA4 (0.1, 1, or 10ng/animal) or vehicle (ethanol 3.2% in saline) administration. Pain-like behavior, inflammation, and dosages were performed to assess the effects of LXA4 in vivo.

Results

LXA4 reduced mechanical and thermal hyperalgesia, histopathological damage, edema, and recruitment of leukocytes without liver, kidney, or stomach toxicity. LXA4 reduced leukocyte migration and modulated cytokine production. These effects were explained by reduced nuclear factor kappa B (NFκB) activation in recruited macrophages. LXA4 improved antioxidant parameters [reduced glutathione (GSH) and 2,2-azino-bis 3-ethylbenzothiazoline-6-sulfonate (ABTS) levels, nuclear factor erythroid 2-related factor 2 (Nrf2) mRNA and Nrf2 protein expression], reducing reactive oxygen species (ROS) fluorescent detection induced by TiO2 in synovial fluid leukocytes. We observed an increase of lipoxin receptor (ALX/FPR2) in transient receptor potential cation channel subfamily V member 1 (TRPV1)+ DRG nociceptive neurons upon TiO2 inflammation. LXA4 reduced TiO2-induced TRPV1 mRNA expression and protein detection, as well TRPV1 co-staining with p-NFκB, indicating reduction of neuronal activation. LXA4 down-modulated neuronal activation and response to capsaicin (a TRPV1 agonist) and AITC [a transient receptor potential ankyrin 1 (TRPA1) agonist] of DRG neurons.

Conclusion

LXA4 might target recruited leukocytes and primary afferent nociceptive neurons to exert analgesic and anti-inflammatory activities in a model resembling what is observed in patients with prosthesis inflammation.

Lipoxin Mimetics and the Resolution of Inflammation

Inflammation and its timely resolution are critical to ensure effective host defense and appropriate tissue repair after injury and or infection. Chronic, unresolved inflammation typifies many prevalent pathologies. The key mediators that initiate and drive the inflammatory response are well defined and targeted by conventional anti-inflammatory therapeutics. More recently, there is a growing appreciation that specific mediators, including arachidonate-derived lipoxins, are generated in self-limiting inflammatory responses to promote the resolution of inflammation and endogenous repair mechanisms without compromising host defense. We discuss the proresolving biological actions of lipoxins and recent efforts to harness their therapeutic potential through the development of novel, potent lipoxin mimetics generated via efficient, modular stereoselective synthetic pathways. We consider the evidence that lipoxin mimetics may have applications in limiting inflammation and reversing fibrosis and the underlying mechanisms.

Exogenous Lipoxin A4 attenuates IL4-induced Mucin Expression in Human Airway Epithelial Cells

Introduction: The proinflammatory cytokine interleukin-4 (IL-4) induces mucus hypersecretion by human airway epithelial cells and the MAP kinase signalling pathway may be important in terms of IL-4-induced MUC5AC gene expression. Lipoxin A₄ (LXA₄) is an arachidonic acid-derived mediator that promotes inflammation by binding to the anti-inflammatory receptors (ALXs) or the formyl-peptide receptor like-1 (FPRL1) protein expressed by airway epithelial cells. Here, we explore the effects of LXA4 on IL-4-induced mucin gene expression in, and secretion from, human airway epithelial cells. Methods: We co-treated cells with IL-4 (20 ng/mL) and LXA₄ (1 nM) and measured the expression levels of mRNAs encoding MUC5AC and 5B via real-time polymerase chain reaction; protein expression levels were determined by Western blotting and immunocytofluorescence. The ability of IL-4 and LXA₄ to suppress protein expression was determined by Western blotting. Results: IL-4 increased MUC5AC and 5B gene and protein expression. LXA₄ suppressed IL-4-induced MUC5AC and 5B gene and protein expression by interacting with the IL4 receptor and mitogen-activated protein kinase (MAPK) pathway, including both phospho-p38 MAPK and phospho-extracellular signal-regulated kinase (phospho-ERK). IL-4 and LXA₄ increased and decreased, respectively, the number of cells that stained with anti-MUC5AC and 5B antibodies. Conclusions: LXA₄ may regulate mucus hypersecretion induced by IL4 in human airway epithelial cells.

Lipoxin alleviates oxidative stress: a state-of-the-art review

OBJECTIVE

This review aims to summarize the capability of lipoxin in regulating oxidative stress.

BACKGROUND

Oxidative stress is defined as an imbalance between the production of free radicals and the antioxidant system, and it is associated with the existence of a large number of oxidation products, such as reactive oxygen species (ROS) and reaction nitrogen species (RNS), causing damage to human tissues through immunoinflammatory responses. Therefore, reducing oxidative stress is vital to alleviate pathological damage. Lipoxin, an acronym for lipoxygenase interaction product, is a bioactive autacoid metabolite of arachidonic acid made by various cell types. Previous studies have shown that lipoxin is associated with a variety of biological functions, including anti-inflammatory, regulating immune responses, promoting the repair of damaged cells, etc. The deficiency of lipoxin is a critical pathological mechanism in different diseases. Moreover, the ability of lipoxin to attenuate oxidative stress is noteworthy, thereby protecting the human body from diverse diseases.

METHODS

We searched papers from PubMed database using search terms, such as lipoxin, lipoxin A4, oxidative stress, and other relevant terms.

RESULTS

A total of 103 articles published over the past 20 years were identified for inclusion. We summarized the capability of lipoxin in regulating oxidative stress and mechanism.

CONCLUSION

Lipoxin is provided with a protective role in attenuating oxidative stress.

Lipoxin A4 regulates M1/M2 macrophage polarization via FPR2-IRF pathway

Lipoxin A4 (LXA4) has been shown to have anti-inflammatory activity, but its underlying molecular mechanisms are not clear. Herein, we investigated the potential role of LXA4 in macrophage polarization and elucidated its possible molecular mechanism. The RAW264.7 macrophage cell line was pretreated with LXA4 with or without lipopolysaccharides (LPSs) and interleukin-4 (IL-4). In cultured macrophages, LXA4 inhibited LPS-induced inflammatory polarization, thereby decreasing the release of proinflammatory cell factors (IL-1β, IL-6, TNF-α) and increasing the release of anti-inflammatory cytokines (IL-4 and IL-10). Notably, the inhibitory effect of LXA4 on inflammatory macrophage polarization was related to the downregulation of p-NF-κB p65 and IRF5 activity, which reduced the LPS-induced phenotypic and functional polarization of M1 macrophages via the FPR2/IRF5 signaling pathway. Moreover, LXA4 also induced the IL-4-induced polarization of M2 macrophages by promoting the FPR2/IRF4 signaling pathway. Therefore, LXA4 regulates M1/M2 polarization of macrophages via the FPR2-IRF pathway.

Specialized Pro-Resolving Lipid Mediators in Neonatal Cardiovascular Physiology and Diseases

Cardiovascular disease remains a leading cause of mortality worldwide. Unresolved inflammation plays a critical role in cardiovascular diseases development. Specialized Pro-Resolving Mediators (SPMs), derived from long chain polyunsaturated fatty acids (LCPUFAs), enhances the host defense, by resolving the inflammation and tissue repair. In addition, SPMs also have anti-inflammatory properties. These physiological effects depend on the availability of LCPUFAs precursors and cellular metabolic balance. Most of the studies have focused on the impact of SPMs in adult cardiovascular health and diseases. In this review, we discuss LCPUFAs metabolism, SPMs, and their potential effect on cardiovascular health and diseases primarily focusing in neonates. A better understanding of the role of these SPMs in cardiovascular health and diseases in neonates could lead to the development of novel therapeutic approaches in cardiovascular dysfunction.

Lipoxin A4 protects against paraquat‑induced acute lung injury by inhibiting the TLR4/MyD88‑mediated activation of the NF‑κB and PI3K/AKT pathways

Paraquat (PQ) causes serious oxidative stress and inflammatory responses, particularly to the lungs. Since lipoxin A4 (LXA4) functions as an anti‑inflammatory mediator, the present study aimed to explore its effects on PQ‑induced acute lung injury (ALI) and to elucidate the possible underlying mechanisms. PQ was administered to male SD rats and RAW264.7 cells to establish a model of poisoning, and LXA4 was used as an intervention drug. LXA4 treatment attenuated PQ‑induced lung injury, and this was accompanied by decreased tumor necrosis factor (TNF)‑α and interleukin (IL)‑1β secretion levels, and reduced oxidative stress damage. Additionally, LXA4 treatment inhibited the activation of the inflammation‑related signaling molecules, Toll‑like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), nuclear factor (NF)‑κB p65, p‑phosphoinositide 3‑kinase (PI3K) and p‑AKT. Furthermore, the in vitro experiments further confirmed that the beneficial effects of LXA4 on PQ‑induced damage were TLR4‑dependent. Hence, the present study demonstrated that LXA4 attenuated PQ‑induced toxicity in lung tissue and RAW264.7 macrophages, and that this protective effect may be closely related to the mitigation of inflammatory responses, oxidative stress damage and the TLR4/MyD88‑mediated activation of the PI3K/AKT/NF‑κB pathway.

Metabolomics reveal dynamic changes in eicosanoid profile in patients with ST-elevation myocardial infarction after percutaneous coronary intervention

Eicosanoids play important roles in the cardiovascular system. The metabolic disorders involving some eicosanoids in the pathophysiologic process include myocardial infarction and myocardial ischaemia-reperfusion injury. Percutaneous coronary intervention (PCI) is often the first-choice strategy for acute ST-segment elevation myocardial infarction (STEMI) according to current guidelines. This study aimed to investigate the dynamic eicosanoid metabolic profile in STEMI patients after PCI. The eicosanoid profiles in plasma of 20 patients at seven times (30 minutes before surgery; 6, 12, 24, and 72 hours after surgery; 1 day before discharge; and 28 days after surgery) were studied by using metabolomics. Levels of PGE2, PGD2, and TXA2 were decreased significantly and EETs contents were increased significantly at 6 hours after PCI. EETs were hydrolysed to DHETs within a short time after surgery (12-72 hours). 20-HETE content was significantly increased. In samples taken at the time of discharge and at follow-up after discharge, LTB4 level continued to increase. This work suggests that change in content of some functional eicosanoids may be involved in cardiac injury and repair after PCI in a synergistic manner.

Resolution-Based Therapies: The Potential of Lipoxins to Treat Human Diseases

Inflammation is an a physiological response instead an essential response of the organism to injury and its adequate resolution is essential to restore homeostasis. However, defective resolution can be the precursor of severe forms of chronic inflammation and fibrosis. Nowadays, it is known that an excessive inflammatory response underlies the most prevalent human pathologies worldwide. Therefore, great biomedical research efforts have been driven toward discovering new strategies to promote the resolution of inflammation with fewer side-effects and more specificity than the available anti-inflammatory treatments. In this line, the use of endogenous specialized pro-resolving mediators (SPMs) has gained a prominent interest. Among the different SPMs described, lipoxins stand out as one of the most studied and their deficiency has been widely associated with a wide range of pathologies. In this review, we examined the current knowledge on the therapeutic potential of lipoxins to treat diseases characterized by a severe inflammatory background affecting main physiological systems, paying special attention to the signaling pathways involved. Altogether, we provide an updated overview of the evidence suggesting that increasing endogenously generated lipoxins may emerge as a new therapeutic approach to prevent and treat many of the most prevalent diseases underpinned by an increased inflammatory response.

Therapeutic Effects of Specialized Pro-Resolving Lipids Mediators on Cardiac Fibrosis via NRF2 Activation

Heart disease is the number one mortality disease in the world. In particular, cardiac fibrosis is considered as a major factor causing myocardial infarction and heart failure. In particular, oxidative stress is a major cause of heart fibrosis. In order to control such oxidative stress, the importance of nuclear factor erythropoietin 2 related factor 2 (NRF2) has recently been highlighted. In this review, we will discuss the activation of NRF2 by docosahexanoic acid (DHA), eicosapentaenoic acid (EPA), and the specialized pro-resolving lipid mediators (SPMs) derived from polyunsaturated lipids, including DHA and EPA. Additionally, we will discuss their effects on cardiac fibrosis via NRF2 activation.

Lipoxin A4-Mediated p38 MAPK Signaling Pathway Protects Mice Against Collagen-Induced Arthritis

The aim of the article was to study the mechanism of Lipoxin A4 (LXA4)-mediated p38 MAPK pathway protecting mice against collagen-induced arthritis (CIA). The impact of LXA4 (0, 5, 10, 15 nM) on synoviocytes proliferation of CIA mice was detected using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. CIA mice were treated with LXA4, SB203580 (a p38 inhibitor), and/or anisomycin (a p38 agonist), and the arthritis severity score in each mouse was determined. The gene or protein expressions were detected with Western Blotting, ELISA, or qRT-PCR. LXA4 inhibited the synoviocytes proliferation of CIA mice with decreased levels of TNF-α, IL-6, IL-1β, and IFN-γ and reduced p-p38/total p38 expression in synoviocytes in a dose-dependent manner. LXA4 levels were decreased in synovial tissues and plasma of CIA mice, but p-p38/total p38 expression was increased in synovial tissues. LXA4 could downregulate p-p38/total p38 expression in synovial tissues of CIA mice. Both LXA4 and SB203580 reduced arthritis severity score of CIA mice with the reduction of synovial tissue hyperplasia and inflammatory cell infiltration. CIA mice treated with LXA4 and SB203580 had lower levels of TNF-α, IL-6, IL-1β, and IFN-γ, accompanying decreased MDA as well as increased SOD, CAT,and GPx. However, anisomycin could reverse the protect effects of LXA4 on CIA mice regarding the abovementioned inflammatory factors and oxidative stress indexes. LXA4 protected mice against collagen-induced arthritis via inhibiting p38 MAPK signaling pathway, which may be a potential new therapeutic target for rheumatoid arthritis.

Neuroinflammation, oxidative stress and their interplay in neuropathic pain: Focus on specialized pro-resolving mediators and NADPH oxidase inhibitors as potential therapeutic strategies

Neuropathic pain (NP) is a chronic condition that results from a lesion or disease of the nervous system, greatly impacting patients' quality of life. Current pharmacotherapy options deliver inadequate and/or insufficient responses and thus a significant unmet clinical need remains for alternative treatments in NP. Neuroinflammation, oxidative stress and their reciprocal relationship are critically involved in NP pathophysiology. In this context, new pharmacological approaches, aiming at enhancing the resolution phase of inflammation and/or restoring redox balance by targeting specific reactive oxygen species (ROS) sources, are emerging as potential therapeutic strategies for NP, with improved efficacy and safety profiles. Several reports have demonstrated that administration of exogenous specialized pro-resolving mediators (SPMs) ameliorates NP pathophysiology. Likewise, deletion or inhibition of the ROS-generating enzyme NADPH oxidase (NOX), particularly its isoforms 2 and 4, results in beneficial effects in NP models. Notably, SPMs also modulate oxidative stress and NOX also regulates neuroinflammation. By targeting neuroinflammatory and oxidative pathways, both SPMs analogues and isoform-specific NOX inhibitors are promising therapeutic strategies for NP.

BML-111 treatment prevents cardiac apoptosis and oxidative stress in a mouse model of autoimmune myocarditis

Myocarditis is an inflammation of the myocardium that can progress to a more severe phenotype of dilated cardiomyopathy (DCM). Three main harmful factors determine this progression: inflammation, cell death, and oxidative stress. Lipoxins and their derivatives are endogenous proresolving mediators that induce the resolution of the inflammatory process. This study aims to determine whether these mediators play a protective role in a murine model of experimental autoimmune myocarditis (EAM) by treating with the lipoxin A₄ analog BML-111. We observed that EAM mice presented extensive infiltration areas that correlated with higher levels of inflammatory and cardiac damage markers. Both parameters were significantly reduced in BML-treated EAM mice. Consistently, cardiac dysfunction, hypertrophy, and emerging fibrosis detected in EAM mice was prevented by BML-111 treatment. At the molecular level, we demonstrated that treatment with BML-111 hampered apoptosis and oxidative stress induction by EAM. Moreover, both in vivo and in vitro studies revealed that these beneficial effects were mediated by activation of Nrf2 pathway through CaMKK2-AMPKα kinase pathway. Altogether, our data indicate that treatment with the lipoxin derivative BML-111 effectively alleviates EAM outcome and prevents cardiac dysfunction, thus, underscoring the therapeutic potential of lipoxins and their derivatives to treat myocarditis and other inflammatory cardiovascular diseases.

Long non‑coding RNA H19 protects H9c2 cells against hypoxia‑induced injury by activating the PI3K/AKT and ERK/p38 pathways

Myocardial ischemia/reperfusion injury often leads to adverse cardiovascular outcomes due to severe hypoxia. The present study aimed to evaluate the effects and mechanism of long non-coding RNA H19 (H19) on rat H9c2 cells with hypoxia-induced injury. H9c2 cells were infected with lentiviruses to express H19 or H19-targeting short hairpin RNA (shRNA), or their respective controls, at a multiplicity of infection of 1:100. H19 expression was determined by reverse transcription-quantitative PCR. Hypoxic injury was induced and assessed by analyzing the level of apoptosis, the cell cycle distribution and the mitochondrial membrane potential using flow cytometry in the different groups. The expression of the PI3K/AKT and the ERK/p38 signaling pathways were analyzed using western blotting. It was found that hypoxia stimulated apoptosis, induced G1 phase cell cycle arrest and increased the mitochondrial depolarization rate in H9c2 cells. When compared with the hypoxic model group, the H19 overexpression group had a significantly reduced rate of apoptosis (P=0.016), a smaller G1 population and a higher S phase population (P=0.018 and P=0.031, respectively), and a reduced mitochondrial depolarization rate (P=0.036). By contrast, the H19 shRNA group exhibited the opposite trends, suggesting that hypoxia-induced injury was alleviated by the overexpression of H19 and was aggravated by the knockdown of H19. The present mechanistic studies revealed that H19 may decrease hypoxia-induced cell injury by activating the PI3K/AKT and ERK/p38 pathways. The results of the present study suggested that H19 may alleviate hypoxia-induced myocardial cell injury through the activation of the PI3K/AKT and ERK/p38 pathways.

Nutritional Mushroom Treatment in Meniere's Disease with Coriolus versicolor: A Rationale for Therapeutic Intervention in Neuroinflammation and Antineurodegeneration

Meniere's disease (MD) represents a clinical syndrome characterized by episodes of spontaneous vertigo, associated with fluctuating, low to medium frequencies sensorineural hearing loss (SNHL), tinnitus, and aural fullness affecting one or both ears. To date, the cause of MD remains substantially unknown, despite increasing evidence suggesting that oxidative stress and neuroinflammation may be central to the development of endolymphatic hydrops and consequent otholitic degeneration and displacement in the reuniting duct, thus originating the otolithic crisis from vestibular otolithic organs utricle or saccule. As a starting point to withstand pathological consequences, cellular pathways conferring protection against oxidative stress, such as vitagenes, are also induced, but at a level not sufficient to prevent full neuroprotection, which can be reinforced by exogenous nutritional approaches. One emerging strategy is supplementation with mushrooms. Mushroom preparations, used in traditional medicine for thousands of years, are endowed with various biological actions, including antioxidant, immunostimulatory, hepatoprotective, anticancer, as well as antiviral effects. For example, therapeutic polysaccharopeptides obtained from Coriolus versicolor are commercially well established. In this study, we examined the hypothesis that neurotoxic insult represents a critical primary mediator operating in MD pathogenesis, reflected by quantitative increases of markers of oxidative stress and cellular stress response in the peripheral blood of MD patients. We evaluated systemic oxidative stress and cellular stress response in MD patients in the absence and in the presence of treatment with a biomass preparation from Coriolus. Systemic oxidative stress was estimated by measuring, in plasma, protein carbonyls, hydroxynonenals (HNE), and ultraweak luminescence, as well as by lipidomics analysis of active biolipids, such as lipoxin A4 and F2-isoprostanes, whereas in lymphocytes we determined heat shock proteins 70 (Hsp72), heme oxygenase-1 (HO-1), thioredoxin (Trx), and γ-GC liase to evaluate the systemic cellular stress response. Increased levels of carbonyls, HNE, luminescence, and F2-isoprostanes were found in MD patients with respect to the MD plus Coriolus-treated group. This was paralleled by a significant (p < 0.01) induction, after Coriolus treatment, of vitagenes such as HO-1, Hsp70, Trx, sirtuin-1, and γ-GC liase in lymphocyte and by a significant (p < 0.05) increase in the plasma ratio-reduced glutathione (GSH) vs. oxidized glutathione (GSSG). In conclusion, patients affected by MD are under conditions of systemic oxidative stress, and the induction of vitagenes after mushroom supplementation indicates a maintained response to counteract intracellular pro-oxidant status. The present study also highlights the importance of investigating MD as a convenient model of cochlear neurodegenerative disease. Thus, searching innovative and more potent inducers of the vitagene system can allow the development of pharmacological strategies capable of enhancing the intrinsic reserve of vulnerable neurons, such as ganglion cells to maximize antidegenerative stress responses and thus providing neuroprotection.

Lipoxin A4 attenuates hyperoxia‑induced lung epithelial cell injury via the upregulation of heme oxygenase‑1 and inhibition of proinflammatory cytokines

The present study examined whether lipoxin A4 (LXA4) increases the expression of HO‑1, and inhibits the production of interleukin 6 (IL‑6) and monocyte chemotactic protein 1 (MCP‑1) in LXA4‑induced protection during hyperoxia‑induced injury in murine lung epithelial cells (MLE‑12) and what signal pathway may participate in the actions of LXA4 inhibiting IL‑6 and MCP‑1. MLE‑12 cells were exposed to air or hyperoxia with or without pretreatment with LXA4, Zinc protoporphyrin IX (ZnPP‑IX), IL‑6, anti‑IL‑6, MCP‑1, anti‑MCP‑1, inhibitors of p38 mitogen‑activated protein kinase (p38 MAPK), protein kinase B (Akt) and extracellular signal‑regulated kinase 1/2 (ERK1/2) signaling pathways. The cell survival rates, cell viability, apoptosis rates, expression of superoxide dismutase (SOD), heme oxygenase‑1 (HO‑1), IL‑6 and MCP‑1, and the activations of p38 MAPK, ERK1/2 and Akt were measured. LXA4 significantly increased the cell survival rates, cell viability, SOD levels and HO‑1 expression, reduced the apoptosis rates, and inhibited the MCP‑1 and IL‑6 levels induced by hyperoxia in cells. ZnPP‑IX, an inhibitor of HO‑1, blocked LXA4‑induced protection on cell viability in cells exposed to hyperoxia. Anti‑IL‑6 and anti‑MCP‑1 improved the cell viability of cells exposed to hyperoxia. Inhibition of p38 MAPK and ERK1/2 blocked the expression of MCP‑1 and IL‑6 induced by hyperoxia. LXA4 inhibited the activation of p38 MAPK and ERK1/2 induced by hyperoxia, and increased the activation of the Akt signaling pathway, which was inhibited by hyperoxia. Therefore, LXA4 attenuated hyperoxia‑induced injury in MLE‑12 cells via the upregulation of HO‑1 expression. The protection of LXA4 in hyperoxia‑induced cell injury may be associated with the downregulation IL‑6 and MCP‑1 levels via the inhibition of the p38 MAPK and ERK1/2 signaling pathways.

Proresolving Lipid Mediators: Endogenous Modulators of Oxidative Stress

Specialized proresolving mediators (SPMs) are a novel class of endogenous lipids, derived by ω-6 and ω-3 essential polyunsaturated fatty acids such as arachidonic acid (AA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) that trigger and orchestrate the resolution of inflammation, which is the series of cellular and molecular events that leads to spontaneous regression of inflammatory processes and restoring of tissue homeostasis. These lipids are emerging as highly effective therapeutic agents that exert their immunoregulatory activity by activating the proresolving pathway, as reported by a consistent bulk of evidences gathered in the last two decades since their discovery. The production of reactive oxygen (ROS) and nitrogen (RNS) species by immune cells plays indeed an important role in the inflammatory mechanisms of host defence, and it is now clear that oxidative stress, viewed as an imbalance between such species and their elimination, can lead to many chronic inflammatory diseases. This review, the first of its kind, is aimed at exploring the manifold effects of SPMs on modulation of reactive species production, along with the mechanisms through which they either inhibit molecular signalling pathways that are activated by oxidative stress or induce the expression of endogenous antioxidant systems. Furthermore, the possible role of SPMs in oxidative stress-mediated chronic disorders is also summarized, suggesting not only that their anti-inflammatory and proresolving properties are strictly associated with their antioxidant role but also that these endogenous lipids might be exploited in the treatment of several pathologies in which uncontrolled production of ROS and RNS or impairment of the antioxidant machinery represents a main pathogenetic mechanism.

Formyl peptide receptor 1 up-regulation and formyl peptide receptor 2/3 down-regulation of blood immune cells along with defective lipoxin A4/resolvin D1 production in obstructive sleep apnea patients

BACKGROUND

This study aims to investigate the role of FPR 1/2/3 expressions in patients with obstructive sleep apnea (OSA).

METHOD

We made cross-sectional comparisons of FPR1/2/3 expressions of blood neutrophil, M1/M2a monocyte, and natural killer (NK) cell between 16 healthy subjects (HS), 16 primary snoring (PS) subjects, 46 treatment-naive OSA patients, and 18 severe OSA patients under long-term continuous positive airway pressure treatment (severe OSA on CPAP).

RESULTS

FPR1 expressions on neutrophil were increased in treatment-naive OSA and severe OSA on CPAP groups versus either HS or PS. FPR2 expressions on neutrophil were decreased in treatment-naive OSA versus HS, and returned to normal in severe OSA on CPAP group. FPR1/FPR2 expression ratio on neutrophil was increased in treatment-naive OSA versus either HS or PS. Serum lipoxin A4, resolvin D1 levels, and FPR3 expressions of M1, M2a and NK cells were all decreased in treatment-naive OSA versus HS. OSA patients with hypertension had decreased FPR2 expressions on neutrophil and FPR3 expressions of NK cell. FPR1 expression, FPR1/FPR2 expression ratio on neutrophil, and FPR3 expression of M1 cell were all reversed after > 6-month CPAP treatment in 9 selected patients. In vitro intermittent hypoxia with re-oxygenation treatment in THP-1 cells resulted in increased FPR1/FPR2 expression ratio of M1 cells, and increased FPR1/FPR3 expression ratio of M2a cells.

CONCLUSIONS

FPR1 over-expression and insufficiency of FPR2 and FPR3 in association with defective lipoxin A4 and resolving D1 production were associated with disease severity of OSA and its adverse consequences.

The potential role of HO-1 in regulating the MLK3-MKK7-JNK3 module scaffolded by JIP1 during cerebral ischemia/reperfusion in rats

Heme oxygenase (HO-1), which may be induced by Cobaltic protoporphyrin IX chloride (CoPPIX) or Rosiglitazone (Ros), is a neuroprotective agent that effectively reduces ischemic stroke. Previous studies have shown that the neuroprotective mechanisms of HO-1 are related to JNK signaling. The expression of HO-1 protects cells from death through the JNK signaling pathway. This study aimed to ascertain whether the neuroprotective effect of HO-1 depends on the assembly of the MLK3-MKK7-JNK3 signaling module scaffolded by JIP1 and further influences the JNK signal transmission through HO-1. Prior to the ischemia-reperfusion experiment, CoPPIX was injected through the lateral ventricle for 5 consecutive days or Ros was administered via intraperitoneal administration in the week prior to transient ischemia. Our results demonstrated that HO-1 could inhibit the assembly of the MLK3-MKK7-JNK3 signaling module scaffolded by JIP1 and could ultimately diminish the phosphorylation of JNK3. Furthermore, the inhibition of JNK3 phosphorylation downregulated the level of p-c-Jun and elevated neuronal cell death in the CA1 of the hippocampus. Taken together, these findings suggested that HO-1 could ameliorate brain injury by regulating the MLK3-MKK7-JNK3 signaling module, which was scaffolded by JIP1 and JNK signaling during cerebral ischemia/reperfusion.

Lipoxin A4 Attenuates Bronchopulmonary Dysplasia via Upregulation of Let-7c and Downregulation of TGF-β1 Signaling Pathway

Transforming growth factor-β (TGF-β) superfamily members are key regulators for lung development and progress of bronchopulmonary dysplasia (BPD). The mechanisms by which lipoxin A₄ (LXA₄) attenuates development of BPD have not been clarified. Neonatal murine BPD models were inducted by hyperoxia treatment. Neonatal mice were exposed to room air or 85% O₂ hyperoxia with or without treatment with 5S,6R-methyl-LXA₄ or anti-TGF-β antibodies. Mouse lung epithelial cells (MLE-12 cells) and mouse embryonic fibroblasts (NIH/3T3 cells) were cultured in room air or 85% O₂ followed by treatment of LXA₄, anti-TGF-β antibodies, and let-7c mimic/anti-microRNA transfections. Treatment with 5S,6R-methyl-LXA₄ and anti-TGF-β antibodies both attenuated the mice alveolar simplification induced by hyperoxia. Hyperoxia treatment significantly altered pulmonary basal mRNA and protein expressions of several important extracellular matrix (ECM) and ECM remodeling proteins including fibronectin, α-smooth muscle actin (α-SMA), tissue inhibitor of metalloproteinase-1 (TIMP-1), elastin, tenascin C, collagen I, and matrix metalloproteinase-1 (MMP-1). 5S,6R-methyl-LXA₄ and anti-TGF-β antibodies suppressed the mRNA and protein expressions of TGF-β₁ and TGF-βR1 but not TGF-βR2 in the lungs exposed to hyperoxia. Treatment with LXA₄ and anti-TGF-β antibodies alleviated hyperoxia-induced injury of the NIH/3T3 cells identified by morphologic observation and flow cytometry, and expressions of ECM, ECM remodeling proteins, and TGF-β₁ signaling pathway, but reversed by transfection with let-7c anti-miRNA. LXA₄ upregulated the let-7c expression in MLE-12 cells, transfection with let-7c anti-miRNA, inhibited the LXA₄-induced let-7c expression in MLE-12 cells exposed to hyperoxia and reduced the relative luciferase activity of let-7c binding with let-7c binding sites of the TGF-βR1 3' UTR. Treatment with 5S,6R-methyl-LXA₄ and anti-TGF-β antibodies significantly improved histology, ECM, and ECM remodeling proteins in the lungs isolated from the murine BPD model induced by hyperoxia. The LXA₄-imparted protective effects on hyperoxia-induced lung injury are mediated by upregulation of let-7c and inhibition of TGF-β₁ and subsequent downregulation of TGF-β₁ signaling pathway.

Lipoxin A4 protects against spinal cord injury via regulating Akt/nuclear factor (erythroid-derived 2)-like 2/heme oxygenase-1 signaling

Spinal cord injury (SCI) is a devastating physical trauma worldwide. The mechanisms of SCI are still not clear and the effective treatment is limited. Lipoxin A4 (LXA4) possesses anti-inflammatory and neuroprotective effects. The present study was designed to further evaluate the molecular mechanisms of LXA4-induced protective effects in a rat model of SCI. We found that LXA4 increased Basso, Beattie and Bresnahan (BBB) scores, increased mechanical paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) to a radiant heat, reduced the lesion volume, decreased Bax mRNA expression and increased Bcl-2 expression after SCI. The phosphorylation of Akt and protein expression of Nrf2 and HO-1 were reduced after SCI. LXA4 treatment significantly inhibited the reduction of Akt phosphorylation and Nrf2 and HO-1 protein expression. Injection of LY294002 notably inhibited the phosphorylation of Akt, and the expression of total Akt and Nrf2 and HO-1 after SCI in LXA4-treated rats. LY294002 prohibited LXA4-induced effects after SCI. shNrf2 injection markedly decreased both Nrf2 and HO-1 expression in LXA4-treated rats after SCI. ZnPP notably decreased HO-1 expression but did not markedly affect Nrf2 expression. shNrf2 and ZnPP prohibited LXA4-induced increase of BBB scores, and PWT and PWL, decrease of lesion volume of spinal cord, reduction of Bax expression and increase of Bcl-2 expression. The results indicate that LXA4 protects against SCI through Akt/Nrf2/HO-1 signaling. The data provide novel insights into the mechanisms of LXA4-mediated neuprotective effects against SCI and suggest that LXA4 may be a potential therapeutic agent for SCI and its associated complications.

Regulation of inflammation by lipid mediators in oral diseases

Lipid mediators (LM) of inflammation are a class of compounds derived from ω-3 and ω-6 fatty acids that play a wide role in modulating inflammatory responses. Some LM possess pro-inflammatory properties, while others possess proresolving characteristics, and the class switch from pro-inflammatory to proresolving is crucial for tissue homeostasis. In this article, we review the major classes of LM, focusing on their biosynthesis and signaling pathways, and their role in systemic and, especially, oral health and disease. We discuss the detection of these LM in various body fluids, focusing on diagnostic and therapeutic applications. We also present data showing gender-related differences in salivary LM levels in healthy controls, leading to a hypothesis on the etiology of inflammatory diseases, particularly Sjögren's syndrome. We conclude by enumerating open areas of research where further investigation of LM is likely to result in therapeutic and diagnostic advances.

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.

Signal transduction involved in lipoxin A4‑induced protection of tubular epithelial cells against hypoxia/reoxygenation injury

Previous studies have reported that lipoxin A₄ (LXA₄) may exert a renoprotective effect on ischemia/reperfusion injury in various animal models. The underlying mechanism of LXA₄-induced renoprotection during ischemia/reperfusion injury remains to be elucidated. The present study investigated LXA₄-induced protection on renal tubular cells subjected to hypoxia/reoxygenation (H/R) injury, and determined the effects of peroxisome proliferator-activated receptor-γ (PPARγ) and heme oxygenase-1 (HO-1) on LXA₄ treatment. HK-2 human tubular epithelial cells exposed to H/R injury were pretreated with LXA₄, signal molecule inhibitors or the HO-1 inhibitor zinc protoporphyrin-IX, or were transfected with PPARγ small interfering RNA (siRNA) or nuclear factor E2-related factor 2 (Nrf2) siRNA. The protein and mRNA expression levels of PPARγ and HO-1 were analyzed using western blotting and reverse transcription-quantitative polymerase chain reaction. Binding activity of Nrf2 to the HO-1 E1 enhancer was determined using chromatin immunoprecipitation. Nrf2 binding to the HO-1 antioxidant responsive element (ARE) was assessed using electrophoretic mobility shift assay. Preincubation of cells with LXA₄ exposed to H/R injury led to a decreased production of inducible nitrogen oxide synthase, malondialdehyde, γ-glutamyl transpeptidase, leucine aminopeptidase and N-acetyl-β-glucosaminidase. In addition, LXA₄ pretreatment increased cell viability, protein and mRNA expression levels of PPARγ and HO-1 and PPARγ and HO-1 promoter activity. SB20358 is a p38 mitogen-activated protein kinase (p38 MAPK) pathway inhibitor, which reduced LXA₄-induced PPARγ expression levels. LXA₄ treatment upregulated p38 MAPK activation, Nrf2 nuclear translocation and increased binding activity of Nrf2 to HO-1 ARE and E1 enhancer in cells exposed to H/R injury. Transfection of the cells with PPARγ siRNA reduced the LXA₄-induced Nrf2 translocation. Transfection of the cells with PPARγ siRNA or Nrf2 siRNA also reduced the LXA₄-induced increase in HO-1 expression. In conclusion, LXA₄-induced protection of renal tubular cells against H/R injury was associated with the induction of PPARγ and HO-1, via activation of the p38 MAPK pathway, as well as Nrf2 nuclear translocation and binding to HO-1 ARE and E1 enhancer. Therefore, LXA₄-induced renoprotection is associated with activation of the p38 MAPK/PPARγ/Nrf2-ARE/HO-1 pathway.

Electroacupuncture pretreatment attenuates spinal cord ischemia-reperfusion injury via inhibition of high-mobility group box 1 production in a LXA4 receptor-dependent manner

Paraplegia caused by spinal cord ischemia is a severe complication following surgeries in the thoracic aneurysm. HMGB1 has been recognized as a key mediator in spinal inflammatory response after spinal cord injury. Electroacupuncture (EA) pretreatment could provide neuroprotection against cerebral ischemic injury through inhibition of HMGB1 release. Therefore, the present study aims to test the hypothesis that EA pretreatment protects against spinal cord ischemia-reperfusion (I/R) injury via inhibition of HMGB1 release. Animals were pre-treated with EA stimulations 30min daily for 4 successive days, followed by 20-min spinal cord ischemia induced by using a balloon catheter placed into the aorta. We found that spinal I/R significantly increased mRNA and cytosolic protein levels of HMGB1 after reperfusion in the spinal cord. The EA-pretreated animals displayed better motor performance after reperfusion along with the decrease of apoptosis, HMGB1, TNF-α and IL-1β expressions in the spinal cord, whereas these effects by EA pretreatment was reversed by rHMGB1 administration. Furthermore, EA pretreatment attenuated the down-regulation of LXA₄ receptor (ALX) expression induced by I/R injury, while the decrease of HMGB1 release in EA-pretreated rats was reversed by the combined BOC-2 (an inhibitor of LXA₄ receptor) treatment. In conclusion, EA pretreatment may promote spinal I/R injury through the inhibition of HMGB1 release in a LXA₄ receptor-dependent manner. Our data may represent a new therapeutic technique for treating spinal cord ischemia-reperfusion injury.

BML-111 Attenuates Renal Ischemia/Reperfusion Injury Via Peroxisome Proliferator-Activated Receptor-α-Regulated Heme Oxygenase-1

We examine whether BML-111, a lipoxin receptor agonist, inhibits renal ischemia/reperfusion (I/R) injury, and whether peroxisome proliferator-activated receptor-α (PPARα) or heme oxygenase-1 (HO-1) is involved in protective effects of BML-111 on kidney against I/R injury. Rats subjected to renal I/R injury were treated with or without BML-111. Renal histological and immunohistochemical studies were performed. Expressions of phosphorylated p38 mitogen-activated protein kinase (pp38 MAPK), phosphorylated PPARα (pPPARα), and HO-1 were assessed in NRK-52E cells exposed to BML-111. The binding activity of PPARα to peroxisome proliferator-responsive element (PPRE) on HO-1 promoter in the cells was determined. BML-111 treatment resulted in a marked reduction in the severity of histological features of renal I/R injury, and attenuated the rise in renal myeloperoxidase and malondialdehyde, blood urea nitrogen and creatinine, urinary N-acetyl-β-glucosaminidase, and leucine aminopeptidase levels caused by I/R injury. BML-111 stimulated the renal expressions of pPPARα and HO-1, and cellular messenger RNA (mRNA) and protein expressions of pPPARα and HO-1 which were both blocked by GW6471, a selective PPARα antagonist, and ZnPP-IX, a specific inhibitor of HO-1 pretreatment. The pp38 MAPK inhibitor SB203580 blocked the BML-111-induced expressions of pp38 MAPK, pPPARα, and HO-1 in NRK-52E cells. The binding activity of PPARα to PPRE in nuclear extracts of NRK-52E cells was enhanced by treatment of the cells with BML-111, and was suppressed by GW6471 and SB203580. BML-111 protects the kidney against I/R injury via activation of p38 MAPK/PPARα/HO-1 pathway.

Diabetic macular edema, retinopathy and age-related macular degeneration as inflammatory conditions

Diabetic macular edema (DME) and diabetic retinopathy (DR) are complications affecting about 25% of all patients with long-standing type 1 and type 2 diabetes mellitus and are a major cause of significant decrease in vision and quality of life. Age-related macular degeneration (AMD) is not uncommon, and diabetes mellitus affects the incidence and progression of AMD through altering hemodynamics, increasing oxidative stress, accumulating advanced glycation end products, etc. Recent studies suggest that DME, DR and AMD are inflammatory conditions characterized by a breakdown of the blood-retinal barrier, inflammatory processes and an increase in vascular permeability. Key factors that seem to have a dominant role in DME, DR and AMD are angiotensin II, prostaglandins and the vascular endothelial growth factor and a deficiency of anti-inflammatory bioactive lipids. The imbalance between pro- and anti-inflammatory eicosanoids and enhanced production of pro-angiogenic factors may initiate the onset and progression of DME, DR and AMD. This implies that bioactive lipids that possess anti-inflammatory actions and suppress the production of angiogenic factors could be employed in the prevention and management of DME, DR and AMD.

Overexpression of miR-200a protects cardiomyocytes against hypoxia-induced apoptosis by modulating the kelch-like ECH-associated protein 1-nuclear factor erythroid 2-related factor 2 signaling axis

The kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) signaling axis plays an important role in regulating oxidative stress in ischemic cardiomyocytes. Targeting Keap1 in order to promote Nrf2 activation is considered a potential method for protecting cardiomyocytes against ischemic injury. In recent years, microRNAs (miRNAs or miRs) have emerged as powerful tools for controlling gene expression. The present study aimed to determine whether Keap1-Nrf2 was regulated by specific miRNAs in cardiomyocytes under hypoxic conditions. We demonstrated that miR-200a was significantly downregulated in ischemic myocardial tissues and hypoxic cardiomyocytes. The overexpression of miR-200a was found to protect cardiomyocytes from hypoxia-induced cell damage and the excessive production of reactive oxygen species. Through bioinformatics analysis and a dual-luciferase report assay, miR-200a was found to interact with the 3'-untranslated region of Keap1, the native regulator of Nrf2. Reverse transcription-quantitative polymerase chain reaction and western blot analysis revealed that miR-200a negatively regulated the expression of Keap1. The overexpression of miR-200a significantly increased the nuclear translocation of Nrf2 as well as downstream antioxidant enzyme gene expression. The inhibition of miR-200a displayed the opposite effects. Restoring the expression of Keap1 significantly abrogated the protective effect of miR‑200a. Taken together, these findings indicate that the suppression of Keap1 by miR-200a exerted a cardioprotective effect against hypoxia-induced oxidative stress and cell apoptosis, and suggest that the activation of Nrf2 signaling by miR‑200a represents a novel and promising therapeutic strategy for the treatment of ischemic heart disease.

Endothelial HO-1 induction by model TG-rich lipoproteins is regulated through a NOX4-Nrf2 pathway

Circulating levels of chylomicron remnants (CMRs) increase postprandially and their composition directly reflects dietary lipid intake. These TG-rich lipoproteins likely contribute to the development of endothelial dysfunction, albeit via unknown mechanisms. Here, we investigated how the FA composition of CMRs influences their actions on human aortic endothelial cells (HAECs) by comparing the effects of model CMRs-artificial TG-rich CMR-like particles (A-CRLPs)-containing TGs extracted from fish, DHA-rich algal, corn, or palm oils. HAECs responded with distinct transcriptional programs according to A-CRLP TG content and oxidation status, with genes involved in antioxidant defense and cytoprotection most prominently affected by n-3 PUFA-containing A-CRLPs. These particles were significantly more efficacious inducers of heme oxygenase-1 (HO-1) than n-6 PUFA corn or saturated FA-rich palm CRLPs. Mechanistically, HO-1 induction by all CRLPs requires NADPH oxidase 4, with PUFA-containing particles additionally dependent upon mitochondrial reactive oxygen species. Activation of both p38 MAPK and PPARβ/δ culminates in increased nuclear factor erythroid 2-related factor 2 (Nrf2) expression/nuclear translocation and HO-1 induction. These studies define new molecular pathways coupling endothelial cell activation by model CMRs with adaptive regulation of Nrf2-dependent HO-1 expression and may represent key mechanisms through which dietary FAs differentially impact progression of endothelial dysfunction.

Inhibition of ceramide de novo synthesis as a postischemic strategy to reduce myocardial reperfusion injury

The injury caused by myocardial reperfusion after ischemia can be contained by interventions aimed at reducing the inflammation and the oxidative stress that underlie exacerbation of tissue damage. Sphingolipids are a class of structural and signaling lipid molecules; among them, the inflammation mediator ceramide accumulates in the myocardium upon ischemia/reperfusion. Here, we show that, after transient coronary occlusion in mice, an increased de novo ceramide synthesis takes place at reperfusion in the ischemic area surrounding necrosis (area at risk). This correlates with the enhanced expression of the first and rate-limiting enzyme of the de novo pathway, serine palmitoyltransferase (SPT). The intraventricular administration at reperfusion of myriocin, an inhibitor of SPT, significantly protected the area at risk from damage, reducing the infarcted area by 40.9 % relative to controls not treated with the drug. In the area at risk, myriocin downregulated ceramide, reduced the content in other mediators of inflammation and reactive oxygen species, and activated the Nrf2-HO1 cytoprotective response. We conclude that an enhanced ceramide synthesis takes part in ischemia/reperfusion injury and that myriocin treatment can be proposed as a strategy for myocardial pharmacological postconditioning.

Lipoxin A4 Reduces Inflammation Through Formyl Peptide Receptor 2/p38 MAPK Signaling Pathway in Subarachnoid Hemorrhage Rats

BACKGROUND AND PURPOSE

Lipoxin A4 (LXA4) has been reported to reduce inflammation in several neurological injury models. We studied the effects of LXA4 on neuroinflammation after subarachnoid hemorrhage (SAH) in a rat model.

METHODS

Two hundred and thirty-eight Sprague-Dawley male rats, weight 280-320 g, were used. Exogenous LXA4 (0.3 and 1.0 nmol) were injected intracerebroventricularly at 1.5 hours after SAH. Neurological scores, brain water content, and blood-brain barrier were evaluated at 24 hours after SAH; Morris water maze and T-maze tests were examined at 21 days after SAH. The expression of endogenous LXA4 and its receptor formyl peptide receptor 2 (FPR2), as well as p38, interleukin-1β, and interleukin-6 were studied either by ELISA or by Western blots. Neutrophil infiltration was observed by myeloperoxidase staining. FPR2 siRNA was used to knock down LXA4 receptor.

RESULTS

The expression of endogenous LXA4 decreased, and the expression of FPR2 increased after SAH. Exogenous LXA4 decreased brain water content, reduced Evans blue extravasation, and improved neurological functions and improved the learning and memory ability after SAH. LXA4 reduced neutrophil infiltration and phosphorylation of p38, interleukin-1β, and interleukin-6. These effects of LXA4 were abolished by FPR2 siRNA.

CONCLUSIONS

Exogenous LXA4 inhibited inflammation by activating FPR2 and inhibiting p38 after SAH. LXA4 may serve as an alternative treatment to relieve early brain injury after SAH.

Redox modulation of cellular stress response and lipoxin A4 expression by Coriolus versicolor in rat brain: Relevance to Alzheimer's disease pathogenesis

Increasing evidence supports the notion that oxidative stress-driven neuroinflammation is an early pathological feature in neurodegenerative diseases. As a prominent intracellular redox system involved in neuroprotection, the vitagene system is emerging as a potential neurohormetic target for novel cytoprotective interventions. Vitagenes encode for cytoprotective heat shock proteins 70, heme oxygenase-1, thioredoxin and lipoxin A4. Emerging interest is now focusing on molecules capable of activating the vitagene system as novel therapeutic targets to minimize deleterious consequences associated with free radical-induced cell damage, such as in neurodegeneration. Mushroom-derived lipoxin A4 (LXA4) is an emerging endogenous eicosanoid able to promote resolution of inflammation, acting as an endogenous "braking signal" in the inflammatory process. Mushrooms have long been used in traditional medicine for thousands of years, being now increasingly recognized as rich source of polysaccharopeptides endowed with significant antitumor, antioxidant, antiviral, antibacterial and cytoprotective effects, thereby capable of stimulating host immune responses. Here we provide evidence of a neuroprotective action of the Coriolus mushroom when administered orally to rat. Expression of LXA4 was measured in different brain regions after oral administration of a Coriolus biomass preparation, given for 30 days. LXA4 up-regulation was associated with an increased content of redox sensitive proteins involved in cellular stress response, such as Hsp72, heme oxygenase-1 and thioredoxin. In the brain of rats receiving Coriolus, maximum induction of LXA4 was observed in cortex and hippocampus. Hsps induction was associated with no significant changes in IkBα, NFkB and COX-2 brain levels. Conceivably, activation of LXA4 signaling and modulation of stress-responsive vitagene proteins could serve as a potential therapeutic target for AD-related inflammation and neurodegenerative damage.

Dimethyl sulfoxide attenuates hydrogen peroxide-induced injury in cardiomyocytes via heme oxygenase-1

The antioxidant property of dimethyl sulfoxide (DMSO) was formerly attributed to its direct effects. Our former study showed that DMSO is able to induce heme oxygenase-1 (HO-1) expression in endothelial cells, which is a potent antioxidant enzyme. In this study, we hypothesized that the antioxidant effects of DMSO in cardiomyocytes are mediated or partially mediated by increased HO-1 expression. Therefore, we investigated whether DMSO exerts protective effects against H2 O2 -induced oxidative damage in cardiomyocytes, and whether HO-1 is involved in DMSO-imparted protective effects, and we also explore the underlying mechanism of DMSO-induced HO-1 expression. Our study demonstrated that DMSO pretreatment showed a cytoprotective effect against H2 O2 -induced oxidative damage (impaired cell viability, increased apopototic cells rate and caspase-3 level, and increased release of LDH and CK) and this process is partially mediated by HO-1 upregulation. Furthermore, our data showed that the activation of p38 MAPK and Nrf2 translocation are involved in the HO-1 upregulation induced by DMSO. This study reports for the first time that the cytoprotective effect of DMSO in cardiomyocytes is partially mediated by HO-1, which may further explain the mechanisms by which DMSO exerts cardioprotection on H2 O2 injury. J. Cell. Biochem. 115: 1159-1165, 2014. © 2013 Wiley Periodicals, Inc.

Catalase overexpression prevents nuclear factor erythroid 2-related factor 2 stimulation of renal angiotensinogen gene expression, hypertension, and kidney injury in diabetic mice

This study investigated the impact of catalase (Cat) overexpression in renal proximal tubule cells (RPTCs) on nuclear factor erythroid 2-related factor 2 (Nrf2) stimulation of angiotensinogen (Agt) gene expression and the development of hypertension and renal injury in diabetic Akita transgenic mice. Additionally, adult male mice were treated with the Nrf2 activator oltipraz with or without the inhibitor trigonelline. Rat RPTCs, stably transfected with plasmid containing either rat Agt or Nrf2 gene promoter, were also studied. Cat overexpression normalized systolic BP, attenuated renal injury, and inhibited RPTC Nrf2, Agt, and heme oxygenase-1 (HO-1) gene expression in Akita Cat transgenic mice compared with Akita mice. In vitro, high glucose level, hydrogen peroxide, and oltipraz stimulated Nrf2 and Agt gene expression; these changes were blocked by trigonelline, small interfering RNAs of Nrf2, antioxidants, or pharmacological inhibitors of nuclear factor-κB and p38 mitogen-activated protein kinase. The deletion of Nrf2-responsive elements in the rat Agt gene promoter abolished the stimulatory effect of oltipraz. Oltipraz administration also augmented Agt, HO-1, and Nrf2 gene expression in mouse RPTCs and was reversed by trigonelline. These data identify a novel mechanism, Nrf2-mediated stimulation of intrarenal Agt gene expression and activation of the renin-angiotensin system, by which hyperglycemia induces hypertension and renal injury in diabetic mice.

MMI-0100 inhibits cardiac fibrosis in myocardial infarction by direct actions on cardiomyocytes and fibroblasts via MK2 inhibition

The cell-permeant peptide inhibitor of MAPKAP kinase 2 (MK2), MMI-0100, inhibits MK2 and downstream fibrosis and inflammation. Recent studies have demonstrated that MMI-0100 reduces intimal hyperplasia in a mouse vein graft model, pulmonary fibrosis in a murine bleomycin-induced model and development of adhesions in conjunction with abdominal surgery. MK2 is critical to the pathogenesis of ischemic heart injury as MK2(-/-) mice are resistant to ischemic remodeling. Therefore, we tested the hypothesis that inhibiting MK2 with MMI-0100 would protect the heart after acute myocardial infarction (AMI) in vivo. AMI was induced by placing a permanent LAD coronary ligation. When MMI-0100 peptide was given 30 min after permanent LAD coronary artery ligation, the resulting fibrosis was reduced/prevented ~50% at a 2 week time point, with a corresponding improvement in cardiac function and decrease in left ventricular dilation. In cultured cardiomyocytes and fibroblasts, MMI-0100 inhibited MK2 to reduce cardiomyocyte caspase 3/7 activity, while enhancing primary cardiac fibroblast caspase 3/7 activity, which may explain MMI-0100's salvage of cardiac function and anti-fibrotic effects in vivo. These findings suggest that therapeutic inhibition of MK2 after acute MI, using rationally-designed cell-permeant peptides, inhibits cardiac fibrosis and maintains cardiac function by mechanisms that involve inhibiting cardiomyocyte apoptosis, while enhancing primary cardiac fibroblast cell death.