BML-111, a lipoxin receptor agonist, protects haemorrhagic shock-induced acute lung injury in rats

Current understanding on long non-coding RNAs in immune response to COVID-19

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic threatening the lives and health of people worldwide. Currently, there are no effective therapies or available vaccines for COVID-19. The molecular mechanism causing acute immunopathological diseases in severe COVID-19 is being investigated. Long noncoding RNAs (lncRNAs) have been proven to be involved in many viral infections, such as hepatitis, influenza and acquired immune deficiency syndrome. Many lncRNAs present differential expression between normal tissue and virus-infected tissue. However, the role of lncRNAs in SARS-CoV-2 infection has not been fully elucidated. This study aimed to review the relationship between lncRNAs and viral infection, interferon and cytokine storms in COVID-19, hoping to provide novel insights into promising targets for COVID-19 treatment.

Ivermectin contributes to attenuating the severity of acute lung injury in mice

Ivermectin has been proposed as a potential anti-inflammatory drug in addition to its antiparasitic activity. Here we investigated the potential role of ivermectin in the pathogenesis of acute lung injury (ALI) using the lipopolysaccharide (LPS)- or bleomycin (BLM)-induced mice models. Male C57BL/6 mice were given ivermectin orally every day for the remainder of the experiment at doses of 1 or 2 mg/kg after 24 h of LPS or BLM treatment. Ivermectin reversed severe lung injury caused by LPS or BLM challenge, including mortality, changes in diffuse ground-glass and consolidation shadows on lung CT imaging, lung histopathological scores, lung wet/dry ratio, and protein content in the bronchoalveolar lavage fluid (BALF). Furthermore, ivermectin also reduced total lung BALF inflammatory cells, infiltrating neutrophils, myeloperoxidase activity, and plasma TNF-α and IL-6 levels in mice treated with LPS or BLM. Finally, the mechanism study showed that LPS or BLM administration increased JNK, Erk1/2, and p38 MAPK phosphorylation while decreasing IκBα expression, an inhibitor of NF-κB. However, ivermectin increased IκBα expression but blocked elevated phosphorylated JNK and p38 MAPK, not Erk1/2, in both ALI mice. These findings suggested that ivermectin may alleviate ALI caused by LPS or BLM in mice, partly via lowering the inflammatory response, which is mediated at least by the inhibition of MAPK and NF-κB signaling. Collectively, ivermectin might be used to treat acute lung injury/acute respiratory distress syndrome.

Formyl peptide receptor 2, as an important target for ligands triggering the inflammatory response regulation: a link to brain pathology

Formyl peptide receptors (FPRs) belong to the family of seven-transmembrane G protein-coupled receptors. Among them, FPR2 is a low affinity receptor for N-formyl peptides and is considered the most promiscuous member of FPRs. FPR2 is able to recognize a broad variety of endogenous or exogenous ligands, ranging from lipid to proteins and peptides, including non-formylated peptides. Due to this property FPR2 has the ability to modulate both pro- and anti-inflammatory response, depending on the nature of the bound agonist and on the different recognition sites of the receptor. Thus, FPR2 takes part not only in the proinflammatory response but also in the resolution of inflammation (RoI) processes. Recent data have indicated that the malfunction of RoI may be the background for some central nervous system (CNS) disorders. Therefore, much interest is focused on endogenous molecules called specialized pro-resolving mediators (SPMs), as well as on new synthetic FPR2 agonists, which kick-start the resolution of inflammation (RoI) and modulate its course. Here, we shed some light on the general characteristics of the FPR family in humans and in the experimental animals. Moreover, we present a guide to understanding the "double faced" action of FPR2 activation in the context of immune-related diseases of the CNS.

Could Lipoxins Represent a New Standard in Ischemic Stroke Treatment?

Introduction: Cardiovascular diseases including stroke are one of the most common causes of death. Their main cause is atherosclerosis and chronic inflammation in the body. An ischemic stroke may occur as a result of the rupture of unstable atherosclerotic plaque. Cardiovascular diseases are associated with uncontrolled inflammation. The inflammatory reaction produces chemical mediators that stimulate the resolution of inflammation. One of these mediators is lipoxins—pro-resolving mediators that are derived from the omega-6 fatty acid family, promoting inflammation relief and supporting tissue regeneration. Aim: The aim of the study was to review the available literature on the therapeutic potential of lipoxins in the context of ischemic stroke. Material and Methods: Articles published up to 31 January 2021 were included in the review. The literature was searched on the basis of PubMed and Embase in terms of the entries: ‘stroke and lipoxin’ and ‘stroke and atherosclerosis’, resulting in over 110 articles in total. Studies that were not in full-text English, letters to the editor, and conference abstracts were excluded. Results: In animal studies, the injection/administration of lipoxin A4 improved the integrity of the blood–brain barrier (BBB), decreased the volume of damage caused by ischemic stroke, and decreased brain edema. In addition, lipoxin A4 inhibited the infiltration of neutrophils and the production of cytokines and pro-inflammatory chemokines, such as interleukin (Il-1β, Il-6, Il-8) and tumor necrosis factor-α (TNF-α). The beneficial effects were also observed after introducing the administration of lipoxin A4 analog—BML-111. BML-111 significantly reduces the size of a stroke and protects the cerebral cortex, possibly by reducing the permeability of the blood–brain barrier. Moreover, more potent than lipoxin A4, it has an anti-inflammatory effect by inhibiting the production of pro-inflammatory cytokines and increasing the amount of anti-inflammatory cytokines. Conclusions: Lipoxins and their analogues may find application in reducing damage caused by stroke and improving the prognosis of patients after ischemic stroke.

The Emerging Role of the Double-Edged Impact of Arachidonic Acid- Derived Eicosanoids in the Neuroinflammatory Background of Depression

Eicosanoids are arachidonic acid (AA) derivatives belonging to a family of lipid signalling mediators that are engaged in both physiological and pathological processes in the brain. Recently, their implication in the prolonged inflammatory response has become a focus of particular interest because, in contrast to acute inflammation, chronic inflammatory processes within the central nervous system (CNS) are crucial for the development of brain pathologies including depression. The synthesis of eicosanoids is catalysed primarily by cyclooxygenases (COX), which are involved in the production of pro-inflammatory AA metabolites, including prostaglandins and thromboxanes. Moreover, eicosanoid synthesis is catalysed by lipoxygenases (LOXs), which generate both leukotrienes and anti-inflammatory derivatives such as lipoxins. Thus, AA metabolites have double- edged pro-inflammatory and anti-inflammatory, pro-resolving properties, and an imbalance between these metabolites has been proposed as a contributor or even the basis for chronic neuroinflammatory effects. This review focuses on important evidence regarding eicosanoid-related pathways (with special emphasis on prostaglandins and lipoxins) that has added a new layer of complexity to the idea of targeting the double-edged AA-derivative pathways for therapeutic benefits in depression. We also sought to explore future research directions that can support a pro-resolving response to control the balance between eicosanoids and thus to reduce the chronic neuroinflammation that underlies at least a portion of depressive disorders.

Emerging role of IL-6 and NLRP3 inflammasome as potential therapeutic targets to combat COVID-19: Role of lncRNAs in cytokine storm modulation

The world has witnessed a high morbidity and mortality caused by SARS-CoV-2, and global death toll is still rising. Exaggerated inflammatory responses are thought to be more responsible for infiltrated immune cells accumulation, organ damage especially lung, dyspnea, and respiratory failure rather than direct effect of viral replication. IL-6 and NLRP3 inflammasome are the major immune components in immune responses stimulation upon pathogen infection. It's noteworthy that the function and expression of these components are remarkably influenced by non-coding RNAs including long non-coding RNAs. Given the potential role of these components in organ damage and pathological manifestations of patients infected with COVID-19, their blockage might be a hopeful and promising treatment strategy. Notably, more study on long non-coding RNAs involved in inflammatory responses could elevate the efficacy of anti-inflammatory therapy. In this review we discuss the potential impact of IL-6 and NLRP3 inflammasome blocker drugs on inflammatory responses, viral clearance, and pathological and clinical manifestations. Collectively, anti-inflammatory strategy might pave the way to diminish clinical and pathological manifestations and thereby discharging patients infected with COVID-19 from hospital.

BML-111 attenuates high glucose-induced inflammation, oxidative stress and reduces extracellular matrix accumulation via targeting Nrf2 in rat glomerular mesangial cells

Diabetic nephropathy (DN) is the most paradigmatic complication of diabetes mellitus (DM) and brings about severe social and economic burdens. BML-111 is a potent agonist of Lipoxin A4 and has shown anti-inflammatory function in many diseases. The aim of the study is to investigate the effects of BML-111 on high glucose (HG) -induced mesangial cells. HBZY-1 cells were stimulated by HG with or without BML-111. ML385 was used as an Nrf2 inhibitor. Cell proliferation was measured by CC-K 8 assay. Besides, levels of TNF-α, IL-1, IL-6 and MCP-1 were detected by corresponding ELISA kits. DCFH-DA staining and an available ROS kit were employed to determine the ROS generation. In addition, extracellular matrix (ECM) accumulation was evaluated by immunofluorescence assay and western blot analysis. The protein expressions involved in Nrf2/HO-1 and MAPK pathway were assessed by western blot assay. Results indicated that BML-111 extremely inhibited HBZY-1 cell proliferation induced by HG. Moreover, BML-111 reduced the levels of TNF-α, IL-1, IL-6 and MCP-1, declined intracellular ROS level, and attenuated expression of ECM proteins laminin, fibronectin, collagen IV and TGF-β1. In addition, BML-111 promoted the activation of Nrf2, HO-1, and NQO1, while suppressed the phosphorylation of p38 and JNK. Further, NRF2 silence reversed the inhibitory effects of BML-111 on HG-induce inflammation, oxidative stress and ECM accumulation, accelerate the MAPK signaling, and diminished the expression of Nrf2 pathway. In summary, BML-111 alleviated HG-induced injury in HBZY-1 cells by repressing inflammatory response, oxidative stress and ECM accumulation via activating Nrf2 and inhibiting MAPK pathway.

Effects of the ALX/FPR2 receptors of lipoxin A4 on lung injury induced by fat embolism syndrome in rats

This study was designed to investigate the inflammatory responses in fat embolism syndrome (FES) and the relationship of ALX/FPR2 receptors and lipoxin A₄ (LXA₄) in FES models. In this model, lung injury score, lung tissue wet-to-dry (W/D) ratio and total protein concentration in bronchoalveolar lavage fluid (BALF) were increased compared with those of the control group. Meanwhile, the number of leukocytes and neutrophils was significantly increased in the FES group, as was the myeloperoxidase (MPO) activity and mRNA expression. In addition, the release of TNF-α and IL-1β was increased. Then, we explored whether LXA₄ and ALX/FPR2 were involved in the pathological process of FES. The LXA₄ concentration in the experimental groups was markedly higher than that in the control group. At the same time, the protein and mRNA levels of ALX/FPR2 were upregulated in the rat model of FES. Moreover, rats treated with BML-111, an agonist for the ALX/FPR2 receptor of LXA₄, showed a lower inflammatory response than mice treated with fat alone. However, the role of BML-111 in fat emboli (FE)-induced acute lung injury (ALI) was attenuated by BOC-2, an antagonist of the ALX/FPR2 receptor of LXA₄. Our results demonstrated that the inflammatory response may play an important role in the pathogenesis of FES and that the activation of the ALX/FPR2 receptor for LXA₄ can decrease the inflammatory response and may be a therapeutic target for FE-induced ALI.

BML-111 suppresses TGF-β1-induced lung fibroblast activation in vitro and decreases experimental pulmonary fibrosis in vivo

Pulmonary fibrosis is an aggressive end‑stage disease. Transforming growth factor‑β1 (TGF‑β1) mediates lung fibroblast activation and is essential for the progress of pulmonary fibrosis. BML‑111, a lipoxinA4 (LXA4) receptor (ALX) agonist, has been reported to possess anti‑fibrotic properties. The present study aimed to elucidate whether BML‑111 inhibits TGF‑β1‑induced mouse embryo lung fibroblast (NIH3T3 cell line) activation in vitro and bleomycin (BLM)‑induced pulmonary fibrosis in vivo. In vitro experiments demonstrated that BML‑111 treatment inhibits TGF‑β1‑induced NIH3T3 cell viability and the expression of smooth muscle α actin (α‑SMA), fibronectin and total collagen. Furthermore, this suppressive effect was associated with mothers against decapentaplegic homolog (Smad)2/3, extracellular signal‑regulated kinase (ERK) and Akt phosphorylation interference. In vivo experiments revealed that BML‑111 treatment markedly improved survival rate and ameliorated the destruction of lung tissue structure. It also reduced interleukin‑1β (IL‑1β), tumor necrosis factor‑α (TNF‑α) and TGF‑β1 expression in the BLM intratracheal mouse model. In addition, the expression ofα‑SMA and extracellular matrix (ECM) deposition (total collagen, hydroxyproline and fibronectin) were also suppressed following BML‑111 treatment. However, BOC‑2, an antagonist of ALX, partially weakened the effects of BML‑111. In conclusion, these results indicated that BML‑111 inhibits TGF‑β1‑induced fibroblasts activation and alleviates BLM‑induced pulmonary fibrosis. Therefore, BML‑111 may be used as a potential therapeutic agent for pulmonary fibrosis treatment.

Magnoflorine Ameliorates Lipopolysaccharide-Induced Acute Lung Injury via Suppressing NF-κB and MAPK Activation

Acute lung injury (ALI) which is featured by a strong pulmonary inflammation, is a major cause of morbidity and mortality in critically ill patients. Magnoflorine, a quaternary alkaloid isolated from Chinese herb Magnolia or Aristolochia, has been reported to have potent anti-inflammatory properties. However, the effect of magnoflorine on lipopolysaccharide (LPS)-induced ALI in mice has not been reported. The purpose of the present study is to investigate the anti-inflammatory effect of magnoflorine on LPS-induced ALI and elucidate its possible molecular mechanisms in RAW264.7 cells. The results of histopathological changes as well as the myeloperoxidase (MPO) activity indicated that magnoflorine significantly alleviated the lung injury induced by LPS. In addition, qPCR results showed that magnoflorine dose-dependently decreased the expression of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. Immunofluorescence assay also confirmed that the level of Toll-like receptor 4 (TLR4) induced by LPS was inhibited by magnoflorine treatment. Further experiments were performed using Western blotting to detect the expression of related proteins in the NF-κB and MAPK signaling pathways. The results showed that magnoflorine suppressed the levels of phosphorylated p65, IκBα, p38, ERK, and JNK. In conclusion, all data indicate that magnoflorine could protect against LPS-induced inflammation in ALI at least partially by inhibiting TLR4-mediated NF-κB and MAPK signaling pathways.

BML-111 Reduces Neuroinflammation and Cognitive Impairment in Mice With Sepsis via the SIRT1/NF-κB Signaling Pathway

Sepsis is a life-threatening state of organ dysfunction caused by infection and which can induce severe neurological disorders that lead to neuroinflammation and cognitive impairment. Inflammation has been reported to cause neuronal apoptosis in sepsis, which can finally lead to cognitive impairment. Previous studies have suggested that BML-111 can exhibit anti-inflammatory and proresolution activities. Additionally, silent information regulator 1 (SIRT1) can inhibit the NF-κB signaling pathway in an inflammation state. However, the role of the SIRT1/NF-κB signaling pathway in the protective effects of BML-111 against sepsis-induced neuroinflammation and cognitive impairment remains unclear. This study aimed to determine the effects of BML-111 on neuroinflammation and cognitive impairment induced by sepsis. Male C57BL/6J mice were subjected to cecal ligation and puncture (CLP) or a sham operation. BML-111 was administered via intracerebroventricular injection (0.1 mg/kg) immediately after CLP. Boc-2 (50 μg/kg) was administered intracerebroventricularly 30 min before CLP, and EX527 (10 μg) was administered every 2 days for a total of three times before CLP, also intracerebroventricularly. Some of the surviving mice underwent open-field, novel-object-recognition, and fear-conditioning behavioral tests at 7 days after surgery. Some of the other surviving mice were killed at 24 h after surgery to assess synaptic damage (PSD95 and Synapsin1), markers of inflammation [tumor necrosis factor alpha (TNF-α) and interleukin (IL)-1β], cytoplasmic p65, nuclear p65, Ac- NF-κB and SIRT1. At 48 h after CLP, TUNEL and glia-activation by immunofluorescence investigations were performed on a separate cohort of surviving animals. The results suggested that sepsis resulted in cognitive impairment, which was accompanied by the decreased the expression of PSD95 and Synapsin1, increased amount of TUNEL-positive cells and the activation of glias, increased production of TNF-α and IL-1β, increased expression of nuclear p65, Ac- NF-κB, and decreased expression of SIRT1 and cytoplasmic p65. It is especially notable that these abnormalities could be reduced by BML-111 treatment. EX527, an SIRT1 inhibitor, abolished the effects of BML-111. These results demonstrate that BML-111 can reduce the neuroinflammation and cognitive impairment induced by sepsis via SIRT/NF-κB signaling pathway.

BML-111 alleviates acute lung injury through regulating the expression of lncRNA MALAT1

BML-111 is a lipoxin receptor agonist that plays a vital role on inflammation. MALAT1 is reported to mediate lung injury. ALI rat model was established using the method of venous cannula. Pulmonary microvascular endothelial cells (PMVEC) of rats were isolated using immunomagnetic separation method. Hematoxylin-eosin (HE) staining was performed to observe the lung injury degree. Real-time PCR and western blot were performed to detect the genes expression. ELIAS was used to determine the level of TNF-α and IL-6. RNA pull-down and RIP were carried out to affirm the relationship between MALAT1 and TLR4. The lung injury score and lung wet/dry weight ratio was significantly increased in ALI rats, while BML-111 treatment significantly decreased it, the HE staining directly revealed the lung injury. The expression of MALAT1 was decreased, while TLR4 was increased in ALI rats, BML-111 stimulation significantly reversed it. MALAT1 targets TLR4 to regulate its expression. TLR4 regulated the inflammation and cell apoptosis of PMVEC via NF-κB and p38 MAPK signaling pathway. The down-regulated MALAT1 mediates the mechanism of ALI by regulating of NF-κB and p38 MAPK signaling pathways via TLR4, while BML-111 stimulation significantly alleviated the ALI by regulating the expression of MALAT1.

Expression level of 12-amino acid triggering receptor on myeloid cells-like transcript 1 derived peptide alleviates lipopolysaccharide-induced acute lung injury in mice

Acute lung injury (ALI) is a critical illness with a high morbidity and mortality rate due to severe inflammation in the lungs. The effects and underlying mechanism of the triggering receptor expressed on myeloid cells‑1 (TREM‑1)‑like transcript‑1‑derived peptide (LR12) on ALI remain unclear. The aim of the present study was to determine whether LR12 attenuates lipopolysaccharide (LPS)‑induced ALI and elucidate the mechanism underlying it. Male C57BL/6 mice were randomly assigned to three groups as follows: Sham group, LPS + scramble group and LPS + LR12 group. Normal saline (NS) or LPS was administrated by intratracheal instillation, and NS, LR12 or LR12 scramble was administered intraperitoneally 30 min later. The treatment was repeated every 3 h three times. Mice were sacrificed 24 h later. Pulmonary pathological changes, the lung wet/dry weight ratio, the macrophage and neutrophil counts in bronchoalveolar lavage fluid and myeloperoxidase (MPO) activity in the lung tissues were observed. The inflammatory cytokines were evaluated by enzyme‑linked immunosorbent assay and lung neutrophil infiltration was detected by immunohistochemistry. Nuclear factor (NF)‑κB p65 and TREM‑1 were analyzed by western blotting, and the activation of NF‑κB was detected by electrophoretic mobility shift assay. LPS‑induced pathohistological injury, edema and neutrophil infiltration were significantly alleviated by TREM‑1 inhibitor, LR12. The proinflammatory cytokines [interleukin (IL)‑6, IL‑1β, tumor necrosis factor‑α] and chemokines (keratinocyte chemokine and monocyte chemoattractant protein‑1) were significantly reduced, whereas the anti‑inflammatory cytokines, IL‑10 were significantly increased by LR12. LR12 was identified to significantly decrease p65 expression levels in the nucleus and inhibit the activity of NF‑κB. Furthermore, LR12 alleviated LPS‑induced ALI by reducing the expression of TREM‑1, increasing the release of soluble TREM‑1 and inhibiting activation of the NF-κB signaling pathway.

Targeting resolution of neuroinflammation after ischemic stroke with a lipoxin A4 analog: Protective mechanisms and long-term effects on neurological recovery

BACKGROUND

Resolution of inflammation is an emerging new strategy to reduce damage following ischemic stroke. Lipoxin A₄ (LXA ₄) is an anti-inflammatory, pro-resolution lipid mediator that reduces neuroinflammation in stroke. Since LXA ₄ is rapidly inactivated, potent analogs have been synthesized, including BML-111. We hypothesized that post-ischemic, intravenous treatment with BML-111 for 1 week would provide neuroprotection and reduce neurobehavioral deficits at 4 weeks after ischemic stroke in rats. Additionally, we investigated the potential protective mechanisms of BML-111 on the post-stroke molecular and cellular profile.

METHODS

A total of 133 male Sprague-Dawley rats were subjected to 90 min of transient middle cerebral artery occlusion (MCAO) and BML-111 administration was started at the time of reperfusion. Two methods of week-long BML-111 intravenous administration were tested: continuous infusion via ALZET ^® osmotic pumps (1.25 and 3.75 μg μl^-1 hr^-1), or freshly prepared daily single injections (0.3, 1, and 3 mg/kg). We report for the first time on the stability of BML-111 and characterized an optimal dose and a dosing schedule for the administration of BML-111.

RESULTS

One week of BML-111 intravenous injections did not reduce infarct size or improve behavioral deficits 4 weeks after ischemic stroke. However, post-ischemic treatment with BML-111 did elicit early protective effects as demonstrated by a significant reduction in infarct volume and improved sensorimotor function at 1 week after stroke. This protection was associated with reduced pro-inflammatory cytokine and chemokine levels, decreased M1 CD40+ macrophages, and increased alternatively activated, anti-inflammatory M2 microglia/macrophage cell populations in the post-ischemic brain.

CONCLUSION

These data suggest that targeting the endogenous LXA ₄ pathway could be a promising therapeutic strategy for the treatment of ischemic stroke. More work is necessary to determine whether a different dosing regimen or more stable LXA ₄ analogs could confer long-term protection.

Maresin 1 Maintains the Permeability of Lung Epithelial Cells In Vitro and In Vivo

Previous reports showed that Maresin 1 (MaR1) possessed organ protection effects and could attenuate acute lung injury. Here, we aim to figure out whether MaR1 can maintain the permeability of lung epithelial cells by regulating the expression of tight junction protein during lung injury. Monolayer of murine lung epithelial cells was stimulated by lipopolysaccharide (LPS) with or without MaR1 and the permeability was evaluated. The expression of Claudin-1 and ZO-1 in lung epithelial cells was analyzed by immunofluorescence staining and western blotting. MaR1 was given to the mice after LPS induced acute lung injury. The permeability of lung was assessed by Evans Blue extravasation, lung wet/dry ratio and protein concentration in bronchoalveolar lavage fluid. Lung injury score was also evaluated. The expression of Claudin-1 and ZO-1 in the lung was analyzed by immunofluorescence staining. Results showed that MaR1 maintained the permeability of lung epithelial cells and upregulated the expression of Claudin-1 and ZO-1 after LPS stimulation. In acute lung injury mice, MaR1 upregulated the expression of Claudin-1 and ZO-1, decreased lung permeability, and reduced lung injury. In summary, this study suggests that MaR1 can maintain the permeability of lung epithelial cells by upregulating the expression of Claudin-1 and ZO-1 in acute lung injury.

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.

Inflammation and Edema in the Lung and Kidney of Hemorrhagic Shock Rats Are Alleviated by Biliary Tract External Drainage via the Heme Oxygenase-1 Pathway

The lung and kidney are two organs that are easily affected by hemorrhagic shock (HS). We investigated roles of biliary tract external drainage (BTED) in inflammation and edema of the lung and kidney in HS and its relationship with the heme oxygenase-1 (HO-1) pathway. Rat models of HS were induced by drawing blood from the femoral artery until a mean arterial pressure (MAP) of 40 ± 5 mmHg was achieved. A MAP of 40 ± 5 mmHg was maintained for 60 min. Thirty-six Sprague-Dawley rats were randomized to the following groups: sham group; HS group; HS + zinc protoporphyrin IX (ZnPP), a specific HO-1 inhibitor, group; HS + BTED group; HS + BTED + ZnPP group; and HS + BTED + bile infusion (BI) group. HO-1 levels, aquaporin-1 levels, and ratios of dry/wet in the lung and kidney increased markedly after BTED, but tumor necrosis factor-α and myeloperoxidase levels in the lung and kidney decreased significantly after BTED under HS conditions. Under the condition that HO-1 was inhibited by ZnPP, all these effects induced by BTED disappeared in the lung and kidney. These results demonstrated that inflammation and edema of the lung and kidney of HS rats are alleviated by BTED via the HO-1 pathway.

BML-111 Protected LPS/D-GalN-Induced Acute Liver Injury in Rats

Lipoxins (LXs) display unique pro-resolving and anti-inflammatory functions in a variety of inflammatory conditions. The present study was undertaken to investigate the effects of BML-111 (5(S),6(R),7-trihydroxyheptanoic acid methyl ester), the agonist of lipoxin A₄ receptor, in a model of Lipopolysaccharides (LPS) and d-Galactosamine (d-GalN) induced acute liver injury, and to explore the mechanisms. Histopathological analyses were carried out to quantify liver injury degree. The activities of myeloperoxidase (MPO) were examined to evaluate the levels of neutrophil infiltration. The activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum were detected to evaluate the functions of the liver. The amounts of tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), and interleukin-1β (IL-1β) were measured using enzyme-linked immunosorbent assay (ELISA), and the expression levels of transforming growth factor-β1(TGF-β1) and cyclooxygenase-2 (COX-2) were examined using Western blotting. The antioxidant capacity, the activities of inducible nitric oxide synthase (iNOS), the contents of malondialdehyde (MDA) and nitric oxide (NO) were analyzed with the kits via biochemical analysis. We established the model of acute liver injury with lipopolysaccharide and d-Galactosamine (LPS/d-GalN): (1) histopathological results and MPO activities, with the activities of AST and ALT in serum, consistently demonstrated LPS and d-GalN challenge could cause severe liver damage, but BML-111 could prevent pathological changes, inhibit neutrophil infiltration, and improve the hepatic function; (2) LPS/d-GalN increased TNF-α, IL-1β, COX-2, and IL-10, while decreasing TGF-β1. However, BML-111 could repress LPS/d-GalN -induced TNF-α, IL-1β and COX-2, meanwhile increasing the expression levels of TGF-β1 and IL-10; (3) LPS/d-GalN inhibited the activities of superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (T-AOC), and hydroxyl radical-scavenging ability, simultaneously increasing the levels of MDA and NO, so also the activity of iNOS. Otherwise, BML-111 could reverse all the phenomena. In a word, BML-111 played a protective role in acute liver injury induced by LPS and d-GalN in rats, through improving antioxidant capacity and regulating the balance of inflammatory cytokines.

Lipoxin A4 Preconditioning Attenuates Intestinal Ischemia Reperfusion Injury through Keap1/Nrf2 Pathway in a Lipoxin A4 Receptor Independent Manner

Oxidative stress plays a critical role in the pathogenesis of intestinal ischemia reperfusion (IIR) injury. Enhancement in endogenous Lipoxin A4 (LXA4), a potent antioxidant and mediator, is associated with attenuation of IIR. However, the effects of LXA4 on IIR injury and the potential mechanisms are unknown. In a rat IIR (ischemia 45 minutes and subsequent reperfusion 6 hours) model, IIR caused intestinal injury, evidenced by increased serum diamine oxidase, D-lactic acid, intestinal-type fatty acid-binding protein, and the oxidative stress marker 15-F2t-Isoprostane. LXA4 treatment significantly attenuated IIR injury by reducing mucosal 15-F2t-Isoprostane and elevating endogenous antioxidant superoxide dismutase activity, accompanied with Keap1/Nrf2 pathway activation. Meanwhile, LXA4 receptor antagonist Boc-2 reversed the protective effects of LXA4 on intestinal injury but failed to affect the oxidative stress and the related Nrf2 pathway. Furthermore, Nrf2 antagonist brusatol reversed the antioxidant effects conferred by LXA4 and led to exacerbation of intestinal epithelium cells oxidative stress and apoptosis, finally resulting in a decrease of survival rate of rat. Meanwhile, LXA4 pretreatment upregulated nuclear Nrf2 level and reduced hypoxia/reoxygenation-induced IEC-6 cell damage and Nrf2 siRNA reversed this protective effect of LXA4 in vitro. In conclusion, these findings suggest that LXA4 ameliorates IIR injury by activating Keap1/Nrf2 pathway in a LXA4 receptor independent manner.

BML-111 attenuates acute lung injury in endotoxemic mice

BACKGROUND

BML-111 is a lipoxin receptor agonist that has protective effects in various lung injury models. We tried to elucidate whether BML-111 could mitigate lung injury in a mouse model of endotoxemia and endothelial hyperpermeability in vitro.

METHODS

The effect of BML-111 on lung injury was evaluated using C57BL/6 mice and human umbilical vein endothelial cells (HUVECs). Male C57BL/6 mice were intraperitoneally injected with normal saline, BML-111, and/or the lipoxin receptor antagonist Boc-2. Then, either lipopolysaccharide (LPS) or normal saline was given intraperitoneally. Lung injury was assessed by a pathohistologic examination for neutrophil infiltration, pulmonary endothelial permeability, and inflammatory cytokines in lung tissue and bronchoalveolar lavage fluid. HUVECs were treated with or without BML-111 before incubation with LPS for 24 h. Boc-2 was also tested as a novel inhibitor of BML-111. A Transwell assay was used to evaluate the permeability of HUVECs. Junction protein expression was also assessed.

RESULTS

BML-111 significantly improved the mouse survival rate, reduced body weight loss, attenuated the pulmonary pathologic changes, inhibited neutrophil infiltration and proinflammatory cytokine production, and mitigated endothelial hyperpermeability. The decreased expression of junction proteins induced by LPS in lung tissue and endothelial cells were upregulated by BML-111. In addition, BML-111 inhibited the activation of the Akt, ERK1/2, and p38 MAPK signaling pathways. However, the beneficial effects of BML-111 were abolished by Boc-2.

CONCLUSIONS

BML-111 attenuated lung injury in endotoxemic mice and mitigated endothelial hyperpermeability by upregulating the expression of junction proteins.

Maresin 1 mitigates LPS-induced acute lung injury in mice

BACKGROUND AND PURPOSE

Acute lung injury (ALI) is a severe illness with a high rate of mortality. Maresin 1 (MaR1) was recently reported to regulate inflammatory responses. We used a LPS-induced ALI model to determine whether MaR1 can mitigate lung injury.

EXPERIMENTAL APPROACH

Male BALB/c mice were injected, intratracheally, with either LPS (3 mg·kg(-1) ) or normal saline (1.5 mL·kg(-1) ). After this, normal saline, a low dose of MaR1 (0.1 ng per mouse) or a high dose of MaR1 (1 ng per mouse) was given i.v. Lung injury was evaluated by detecting arterial blood gas, pathohistological examination, pulmonary oedema, inflammatory cell infiltration, inflammatory cytokines in the bronchoalveolar lavage fluid and neutrophil-platelet interactions.

KEY RESULTS

The high dose of MaR1 significantly inhibited LPS-induced ALI by restoring oxygenation, attenuating pulmonary oedema and mitigating pathohistological changes. A combination of elisa and immunohistochemistry showed that high-dose MaR1 attenuated LPS-induced increases in pro-inflammatory cytokines (TNF-α, IL-1β and IL-6), chemokines [keratinocyte chemokine, monocyte chemoattractant protein-5, macrophage inflammatory protein (MIP)-1α and MIP-1γ], pulmonary myeloperoxidase activity and neutrophil infiltration in the lung tissues. Consistent with these observations, flow cytometry and Western blotting indicated that MaR1 down-regulated LPS-induced neutrophil adhesions and suppressed the expression of intercellular adhesion molecule (ICAM)-1, P-selection and CD24.

CONCLUSIONS AND IMPLICATIONS

High-dose MaR1 mitigated LPS-induced lung injury in mice by inhibiting neutrophil adhesions and decreasing the levels of pro-inflammatory cytokines.

BML-111, a lipoxin receptor agonist, attenuates ventilator-induced lung injury in rats

Mechanical ventilation can cause structural and functional disturbances in the lung termed ventilator-induced lung injury (VILI). The aim of this study was to evaluate whether BML-111, a lipoxin receptor agonist, could attenuate VILI. Following induction of anesthesia and tracheostomy, Sprague-Dawley rats were ventilated with low tidal volume (6 mL/kg) or high tidal volume (20 mL/kg, HVT) for 4 h. Some rats subjected to HVT ventilation received BML-111 or vehicle (saline) by intraperitoneal injection. Some rats subjected to HVT and BML-111(1 mg/kg) received BOC-2 (a FPR2/ALX antagonist) intraperitoneally 30 min before BML-111. Sham rats were tracheotomized without ventilation. Treatment with BML-111 attenuated VILI, as evidenced by improved oxygenation and reduced histological injury compared with HVT-induced lung injury. BML-111 decreased indices of inflammation such as interleukin 1β, interleukin 6, tumor necrosis factor α, and bronchoalveolar lavage neutrophil infiltration. Administration with BML-111 suppressed the decrement of the nuclear factor κB (NF-κB) inhibitor IκB-α, diminished NF-κB activation, and reduced activation of mitogen-activated protein kinase in VILI. This study indicates that BML-111 attenuated VILI via a NF-κB and mitogen-activated protein kinase dependent mechanism. BML-111 may be a promising strategy for alleviation of VILI in patients subjected to mechanical ventilation.

BML-11, a lipoxin receptor agonist, protected carbon tetrachloride-induced hepatic fibrosis in rats

Inflammation plays an important role in the occurrence and development of fibrosis. Lipoxins (LXs) and BML-111 (lipoxin A4 agonist) have been approved for potent anti-inflammatory properties. Previously, we and others had showed LXs and BML-111 could protect acute hepatic injury, inhibit the growth and invasion of hepatic tumor. However, there are few reports dealing with their effects on hepatic fibrosis. To explore whether LXs and the analog could interrupt the process of hepatic fibrosis, the effects of BML-111 on tetrachloride-induced hepatic fibrosis were observed and the possible mechanism were discussed. Sprague-Dawley rats were induced liver fibrosis by carbon tetrachloride (CCl4) for 10 weeks with or without BML-111, and the histopathology and collagen content were employed to quantify hepatic necro-inflammation and fibrosis. Moreover, the expression levels of α-smooth muscle actin (α-SMA), transforming growth factor-β1 (TGF-β1), and platelet-derived growth factor (PDGF) were examined via Western blot or ELISA. Rats treated with BML-111 improved hepatic necro-inflammation and inhibited hepatic fibrosis in association with reduction of α-SMA expression and decreased collagen deposition. Furthermore, BML-111 could downregulate the expressions of TGF-β1 and PDGF significantly. BML-111 played a critical protective role in CCl4-induced hepatic fibrosis through inhibiting the levels of TGF-β1 and PDGF in rats.

Resolvin D1 promotes the interleukin-4-induced alternative activation in BV-2 microglial cells

Background

Microglia play key roles in innate immunity, homeostasis, and neurotropic support in the central nervous system. Similar to macrophages, microglia adopt two different activation phenotypes, the classical and alternative activation. Resolvin D1 (RvD1) is considered to display potent anti-inflammatory and pro-resolving actions in inflammatory models. In this present study, we investigate the effect of RvD1 on IL-4-induced alternative activation in murine BV-2 microglial cells.

Methods

BV-2 cells were incubated with RvD1 alone, IL-4 alone, or the combination of RvD1 and IL-4. Western blot and immunofluorescence were performed to detect protein levels of alternative activation markers arginase 1 (Arg1), chitinase 3-like 3 (Ym1). Moreover, we investigated the effects of RvD1 on IL-4-induced activation of signal transducer and activators of transcription 6 (STAT6) and peroxisome proliferator-activated receptor gamma (PPARγ).

Results

RvD1 promoted IL-4-induced microglia alternative activation by increasing the expression of Arg1 and Ym1. RvD1 also enhanced phosphorylation of STAT6, nuclear translocation of PPARγ and the DNA binding activity of STAT6 and PPARγ. These effects were reversed by butyloxycarbonyl-Phe-Leu-Phe-Leu-Phe (a formyl peptide receptor 2 antagonist). Further, the effects of RvD1 and IL-4 on Arg1 and Ym1 were blocked by the application of leflunomide (a STAT6 inhibitor) or GW9662 (a PPARγ antagonist).

Conclusions

Our studies demonstrate that RvD1 promotes IL-4-induced alternative activation via STAT6 and PPARγ signaling pathways in microglia. These findings suggest that RvD1 may have therapeutic potential for neuroinflammatory diseases.

Neurovascular protection by post-ischemic intravenous injections of the lipoxin A4 receptor agonist, BML-111, in a rat model of ischemic stroke

Resolution of inflammation is an emerging new strategy to reduce damage following ischemic stroke. Lipoxin A4 (LXA4 ) is an anti-inflammatory, pro-resolution lipid mediator with high affinity binding to ALX, the lipoxin A4 receptor. Since LXA4 is rapidly inactivated, potent analogs have been created, including the ALX agonist BML-111. We hypothesized that post-ischemic intravenous administration of BML-111 would provide protection to the neurovascular unit and reduce neuroinflammation in a rat stroke model. Animals were subjected to 90 min of middle cerebral artery occlusion (MCAO) and BML-111 was injected 100 min and 24 h after stroke onset and animals euthanized at 48 h. Post-ischemic treatment with BML-111 significantly reduced infarct size, decreased vasogenic edema, protected against blood-brain barrier disruption, and reduced hemorrhagic transformation. Matrix metalloproteinase-9 and matrix metalloproteinase-3 were significantly reduced following BML-111 treatment. Administration of BML-111 dramatically decreased microglial activation, as seen with CD68, and neutrophil infiltration and recruitment, as assessed by levels of myeloperoxidase and intracellular adhesion molecule-1. The tight junction protein zona occludens-1 was protected from degradation following treatment with BML-111. These results indicate that post-ischemic activation of ALX has pro-resolution effects that limit the inflammatory damage in the cerebral cortex and helps maintain blood-brain barrier integrity after ischemic stroke.

BML-111, a lipoxin receptor agonist, ameliorates 'two-hit'-induced acute pancreatitis-associated lung injury in mice by the upregulation of heme oxygenase-1

The objective of this study is to investigate the effects of BML-111 on acute pancreatitis-associated lung injury (APALI) induced by cerulein with subsequent an LPS administration in mice and its possible mechanisms. One hundred and twenty-eight mice were randomly allocated to four groups, namely the APALI group, the BML-111 pretreatment group, the BM-111 control group, and the control group. The 'two-hit' mice APALI model was established by intraperitoneal injection of cerulein 7 times at hourly intervals and Escherichia coli lipopolysaccharide (LPS) once after the last dose of cerulein immediately. The samples were taken at 3, 6, 12, and 24 h after the last injection. Serum levels of amylase, TNF-a, IL-1β and IL-10, were determined. Histological score of the pancreas and lung, the wet/dry weight ratio, and heme oxygenase-1 (HO-1) expression in the lung were also evaluated. BML-111 pretreatment significantly reduced the serum levels of amylase, TNF-α, IL-1β, the wet/dry weight ratio of lung, and the pathology injury scores of pancreas and lung, and the serum levels of IL-10 were markedly increased. The severity of pancreatic and lung histology were also significantly improved by the administration of BML-111, and the expressions of HO-1 in lung tissues also increased in the BML-111 group compared with those in the APALI group. In conclusion, BML-111 exerts protective effects on APALI induced by cerulein and LPS. In addition to its anti-inflammatory effects, the beneficial effects may also be due to the upregulation of HO-1 expression in the lung tissues.

BML-111 attenuates hemorrhagic shock-induced acute lung injury through inhibiting activation of mitogen-activated protein kinase pathway in rats

BACKGROUND

Hemorrhagic shock activates cellular stress signals and can lead to systemic inflammatory response, organ injury, and death. Mitogen-activated protein kinase (MAPK) acts as a sensor of tissue injury in models of ischemia-reperfusion injury. Lipoxins are endogenous lipid mediators with potent anti-inflammatory and pro-resolving actions. We hypothesized that BML-111 (a lipoxin A4-receptor agonist) attenuates hemorrhagic shock-induced acute lung injury (ALI) through inhibiting activation of the MAPK pathway.

METHODS

We randomized Sprague-Dawley rats into four groups: sham, hemorrhagic shock-resuscitation (HS), HS plus BML-111 (BML-111), and HS plus BML-111 and BOC-2 (BOC-2). Two hours after resuscitation, we collected samples of lung. We obtained bronchoalveolar lavage fluid for neutrophil count. We performed optical microscopy to examine pathologic changes in lungs. Wet/dry ratios, myeloperoxidase expression, interleukin (IL)-1β and IL-6 levels in lung were measured. We evaluated MAPK activation and the DNA binding activity of activator protein-1 in lung.

RESULTS

Treatment with BML-111 reduced the lung damage and wet/dry ratio, neutrophil count in bronchoalveolar lavage fluid, expression of myeloperoxidase, and production of IL-1β and IL-6 in lung. Phosphorylation of MAPK was also decreased by BML-111 in lung. Furthermore, the DNA binding activity of activator protein-1 was blocked by BML-111. An antagonist of the lipoxin A4-receptor, BOC-2, reversed the protective effect of BML-111 on ALI induced by hemorrhagic shock.

CONCLUSIONS

This study indicates that BML-111 attenuated hemorrhagic shock-induced ALI via the MAPK/activator protein-1 signaling pathway. Therefore, BML-111 may have therapeutic potential for hemorrhagic shock-induced ALI.