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The 5-lipoxygenase/leukotriene system has been implicated in both physiological and pathological states within the central nervous system. Understanding how this system interacts with the dopaminergic system could provide valuable insights into dopamine-related pathologies. This study focused on examining both motor and non-motor dopamine-related responses in 5-lipoxygenase/leukotriene-deficient mice. We used pharmacological agents such as amphetamine, apomorphine, and reserpine to challenge the dopaminergic system, evaluating their effects on prepulse inhibition reaction (PPI), general motor activity, and oral involuntary movements. Additionally, we analyzed striatal glial marker expression (GFAP and Iba-1) in reserpine-treated mice. The 5-lipoxygenase/leukotriene-deficient mice exhibited increased spontaneous locomotor activity, including both horizontal and vertical exploration, along with stereotyped behavior compared to wild-type mice. This hyperactivity was reduced by acute apomorphine treatment. Although basal PPI responses were unchanged, 5-lipoxygenase/leukotriene-deficient mice displayed a significant reduction in susceptibility to amphetamine-induced PPI disruption. Conversely, these mice were more vulnerable to reserpine-induced involuntary movements. There were no significant differences in the basal expression of striatal GFAP and Iba-1 positive cells between 5-lipoxygenase/leukotriene-deficient and wild-type mice. However, reserpine treatment significantly increased GFAP immunoreactivity in wild-type mice, an effect not observed in 5-lipoxygenase-deficient mice. Additionally, the percentage of activated microglia was significantly higher in reserpine-treated wild-type mice, an effect absents in 5-lipoxygenase/leukotriene-deficient mice. Our findings suggest that 5-lipoxygenase/leukotriene deficiency leads to a distinctive dopaminergic phenotype, indicating that leukotrienes may influence the modulation of dopamine-mediated responses. [ABSTRACT FROM AUTHOR]

Leukotrienes (LTs) are a group of substances that cause inflammation. They are produced by the enzyme 5-lipoxygenase (5-LOX) from arachidonic acid. Cysteinyl LTs are a group of lipid molecules that have a prominent role in inflammatory signaling in the allergic diseases. Although they are traditionally known for their role in allergic disease, current advancements in bio-medical research have shed light on the involvement of these inflammatory mediators in diseases such as in the inflammation related to central nervous system (CNS) disorders. Among the CNS diseases, LTs, along with 5-LOX and their receptors, have been shown to be associated with multiple sclerosis (MS), Alzheimer's disease (AD), and Parkinson's disease (PD). Through a comprehensive review of current research and experimentation, this investigation provides an insight on the biosynthesis, receptors, and biological effects of LTs in the body. Furthermore, implications of leukotriene signaling in CNS and its intricate role in neurodegeneration are also studied. Through the revelation of these insights, our aim is to establish a foundation for the development of enhanced and focused therapeutic approaches in the continuous endeavor to combat neurodegeneration. Furthermore, the pharmacological inhibition of leukotriene signaling with selective inhibitors offers promising prospects for future interventions and treatments for neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Inflammation is a protective stress response triggered by external stimuli, with 5-lipoxygenase (5LOX) playing a pivotal role as a potent mediator of the leukotriene (Lts) inflammatory pathway. Nordihydroguaiaretic acid (NDGA) functions as a natural orthosteric inhibitor of 5LOX, while 3-acetyl-11-keto-β-boswellic acid (AKBA) acts as a natural allosteric inhibitor targeting 5LOX. However, the precise mechanisms of inhibition have remained unclear. In this study, Gaussian accelerated molecular dynamics (GaMD) simulation was employed to elucidate the inhibitory mechanisms of NDGA and AKBA on 5LOX. It was found that the orthosteric inhibitor NDGA was tightly bound in the protein's active pocket, occupying the active site and inhibiting the catalytic activity of the 5LOX enzyme through competitive inhibition. The binding of the allosteric inhibitor AKBA induced significant changes at the distal active site, leading to a conformational shift of residues 168–173 from a loop to an α-helix and significant negative correlated motions between residues 285–290 and 375–400, reducing the distance between these segments. In the simulation, the volume of the active cavity in the stable conformation of the protein was reduced, hindering the substrate's entry into the active cavity and, thereby, inhibiting protein activity through allosteric effects. Ultimately, Markov state models (MSM) were used to identify and classify the metastable states of proteins, revealing the transition times between different conformational states. In summary, this study provides theoretical insights into the inhibition mechanisms of 5LOX by AKBA and NDGA, offering new perspectives for the development of novel inhibitors specifically targeting 5LOX, with potential implications for anti-inflammatory drug development. [ABSTRACT FROM AUTHOR]

Background: The liver is anatomically divided into eight segments based on the distribution of Glisson's triad. However, the molecular mechanisms underlying each segment and its association with hepatocellular carcinoma (HCC) heterogeneity are not well understood. In this study, our objective is to conduct a comprehensive multiomics profiling of the segmentation atlas in order to investigate potential subtypes and therapeutic approaches for HCC. Methods: A high throughput liquid chromatography‐tandem mass spectrometer strategy was employed to comprehensively analyse proteome, lipidome and metabolome data, with a focus on segment‐resolved multiomics profiling. To classify HCC subtypes, the obtained data with normal reference profiling were integrated. Additionally, potential therapeutic targets for HCC were identified using immunohistochemistry assays. The effectiveness of these targets were further validated through patient‐derived organoid (PDO) assays. Results: A multiomics profiling of 8536 high‐confidence proteins, 1029 polar metabolites and 3381 nonredundant lipids was performed to analyse the segmentation atlas of HCC. The analysis of the data revealed that in normal adjacent tissues, the left lobe was primarily involved in energy metabolism, while the right lobe was associated with small molecule metabolism. Based on the normal reference atlas, HCC patients with segment‐resolved classification were divided into three subtypes. The C1 subtype showed enrichment in ribosome biogenesis, the C2 subtype exhibited an intermediate phenotype, while the C3 subtype was closely associated with neutrophil degranulation. Furthermore, using the PDO assay, exportin 1 (XPO1) and 5‐lipoxygenase (ALOX5) were identified as potential targets for the C1 and C3 subtypes, respectively. Conclusion: Our extensive analysis of the segmentation atlas in multiomics profiling defines molecular subtypes of HCC and uncovers potential therapeutic strategies that have the potential to enhance the prognosis of HCC. [ABSTRACT FROM AUTHOR]

Diverse secondary metabolites are biosynthesized by plants via various enzymatic cascades. These have the capacity to interact with various human receptors, particularly enzymes implicated in the etiology of several diseases. The n-hexane fraction of the whole plant extract of the wild edible plant, Launaea capitata (Spreng.) Dandy was purified by column chromatography. Five polyacetylene derivatives were identified, including (3S,8E)-deca-8-en-4,6-diyne-1,3-diol (1A), (3S)-deca-4,6,8-triyne-1,3-diol (1B), (3S)-(6E,12E)-tetradecadiene-8,10-diyne-1,3-diol (2), bidensyneoside (3), and (3S)-(6E,12E)-tetradecadiene-8,10-diyne-1-ol-3-O-β-D-glucopyranoside (4). These compounds were investigated for their in vitro inhibitory activity against enzymes involved in neuroinflammatory disorders, including cyclooxygenase-2 (COX-2), 5-lipoxygenase (5-LOX), and butyrylcholinesterase (BchE) enzymes. All isolates recorded weak–moderate activities against COX-2. However, the polyacetylene glycoside (4) showed dual inhibition against BchE (IC50 14.77 ± 1.55 μM) and 5-LOX (IC50 34.59 ± 4.26 μM). Molecular docking experiments were conducted to explain these results, which showed that compound 4 exhibited greater binding affinity to 5-LOX (−8.132 kcal/mol) compared to the cocrystallized ligand (−6.218 kcal/mol). Similarly, 4 showed a good binding affinity to BchE (−7.305 kcal/mol), which was comparable to the cocrystallized ligand (−8.049 kcal/mol). Simultaneous docking was used to study the combinatorial affinity of the unresolved mixture 1A/1B to the active sites of the tested enzymes. Generally, the individual molecules showed lower docking scores against all the investigated targets compared to their combination, which was consistent with the in vitro results. This study demonstrated that the presence of a sugar moiety (in 3 and 4) resulted in dual inhibition of 5-LOX and BchE enzymes compared to their free polyacetylenes analogs. Thus, polyacetylene glycosides could be suggested as potential leads for developing new inhibitors against the enzymes involved in neuroinflammation. [ABSTRACT FROM AUTHOR]

The 5-lipoxygenase (5-LOX) pathway gives rise to bioactive inflammatory lipid mediators, such as leukotrienes (LTs). 5-LOX carries out the oxygenation of arachidonic acid to the 5-hydroperoxy derivative and then to the leukotriene A4 epoxide which is converted to a chemotactic leukotriene B4 (LTB4) by leukotriene A4 hydrolase (LTA4H). In addition, LTA4H possesses aminopeptidase activity to cleave the N-terminal proline of a pro-inflammatory tripeptide, prolyl-glycyl-proline (PGP). Based on the structural characteristics of LTA4H, it is possible to selectively inhibit the epoxide hydrolase activity while sparing the inactivating, peptidolytic, cleavage of PGP. In the current study, chalcogen-containing compounds, 4-(4-benzylphenyl) thiazol-2-amine (ARM1) and its selenazole (TTSe) and oxazole (TTO) derivatives were characterized regarding their inhibitory and binding properties. All three compounds selectively inhibit the epoxide hydrolase activity of LTA4H at low micromolar concentrations, while sparing the aminopeptidase activity. These inhibitors also block the 5-LOX activity in leukocytes and have distinct inhibition constants with recombinant 5-LOX. Furthermore, high-resolution structures of LTA4H with inhibitors were determined and potential binding sites to 5-LOX were proposed. In conclusion, we present chalcogen-containing inhibitors which differentially target essential steps in the biosynthetic route for LTB4 and can potentially be used as modulators of inflammatory response by the 5-LOX pathway. [ABSTRACT FROM AUTHOR]

Metabolic activation of indirect-acting carcinogens in target organs is a recognized mechanism of carcinogenesis. This study aimed to determine the role of benzo[a]pyrene (BaP) metabolism enzymes lipoxygenase (LOX), cytochrome P4501A1 (CYP1A1), and prostaglandin synthetase (PGS) in the cytotoxicity and DNA damage induced by BaP in the human tracheobronchial epithelial cells (HBECs) using RNA interference strategy and metabolic enzyme inhibitors. Our results showed that in three epithelial cell lines (HBE, HTR-8/SVneo, and HaCat), BaP significantly upregulated 5-LOX protein expression. 15-LOX-2 expression also increased with increasing BaP concentration, but the change was less pronounced than that of 5-LOX. BaP caused significant cytotoxicity, DNA strand breaks, and 8-hydroxy-2'-deoxyguanosine formation in HBE, which was inhibited by 5-LOXshRNA, a specific inhibitor of 5-LOX (AA861), the CYP1A1 inhibitor α-naphthoflavone, and the PGS inhibitor naproxen. The protective effects of 5-LOXshRNA were stronger than AA861, naproxen and α-naphthoflavone. We conclude that BaP may be activated more by 5-LOX than by CYP1A1 and PGS to produce cytotoxicity and DNA damage in HBE. [ABSTRACT FROM AUTHOR]

In this study, an efficient method that employs 5‐lipoxygenase and acetylcholinesterase as biological target molecules in receptor–ligand affinity ultrafiltration–liquid chromatography was developed for the screening of enzyme inhibitors derived from the Astragalus membranaceus stems and leaves. The effects of the extraction time, number of extraction cycles, ethanol concentration, and liquid–solid ratio on the total yield of the target compounds were investigated using response surface methodology, and the bioactive components were isolated using a combination of semi‐preparative high‐performance liquid chromatography and high‐speed countercurrent chromatography via a two‐phase solvent system consisting of n‐hexane–ethyl acetate–methanol–water (1:6:2:6, v/v/v/v). Subsequently, 10 naturally‐occurring bioactive components in the Astragalus membranaceus stems and leaves, including wogonin, ononin, isoquercitrin, calycosin‐7‐glucoside, 3‐hydroxy‐9,10‐dimethoxyptercarpan, hyperoside, 7,2′‐dihydroxy‐3′,4′‐dimethoxyisoflavan, baicalein, calycosin, and soyasaponin, were screened using affinity ultrafiltration to determine their potential effects against Alzheimer's disease. Consequently, all target compounds had purities higher than 95.0%, and the potential anti‐Alzheimer's disease effect of the obtained bioactive compounds was verified using molecular docking analysis. Based on the results, the back‐to‐back screening of complex enzyme inhibitors and separation of the target bioactive compounds using complex chromatography could provide a new approach to the discovery and preparation of natural active ingredients. [ABSTRACT FROM AUTHOR]

Plant secondary metabolites have a long history of potential use in managing human diseases by inhibiting enzymes that are highly expressed due to various pathogenic conditions. Prostaglandins (PGs) and leukotrienes (LTs) are proinflammatory mediators synthesized from arachidonic acid (AA) by the action of cyclooxygenases (COXs) and lipoxygenases (LOXs), respectively. Particularly, COX-2/5-LOX enzymes play a significant role in inflammatory processes and the pain associated with them. Butyrylcholinesterase (BchE) was recently suggested as a more reliable potential target for sustaining normal cholinergic function. In an attempt to identify new potential COX-2/5-LOX and BchE inhibitors, a phytochemical investigation of Launaea capitata (Spreng.) Dandy (Asteraceae) was executed. This investigation led to the isolation of a new digalactosyldiacylglycerol isomer, namely 1,2-dilinolenoyl-3-O-(α-galactopyranosyl-(1,6)-O-α-D-galactopyranosyl)-sn-glycerol (1) in addition to 1-myristoyl-2-palmitoyl-3-O-(α-galactopyranosyl-(1,6)-O-β-D-galactopyranosyl)-sn-glycerol (2), which was isolated herein for the first time from nature. The structures of the two isolates were elucidated by using 1D-, 2D-NMR, and ESI-MS spectroscopy. Compounds 1 and 2 exhibited good in vitro inhibitory activities against 5-LOX (59.01 and 21.67 μg/mL) and BchE (13.37 and 24.32 μg/mL), respectively. However, they exhibited weak inhibition of COX-2 (110.44 and 179.63 μg/mL, respectively). These inhibitory activities were explained in silico using a computational docking study. The docking results were consistent with the in vitro enzyme inhibitory activity. The lowest binding affinity for 1 and 2 was observed against COX-2 (−7.360 and −5.723 kcal/mol), whereas they exhibited greater binding affinity to 5-LOX (−8.124 and −8.634 kcal/mol), respectively, compared to its natural substrate, AA (−5.830 kcal/mol). Additionally, 1 and 2 exhibited remarkable binding affinity to BchE (−8.313 kcal/mol and −7.502 kcal/mol, respectively), which was comparable to the co-crystallized ligand, thioflavin T (−8.107 kcal/mol). This was related to the multiple and crucial hydrogen bonding interactions of these compounds with the amino acid residues in the active sites of the investigated enzymes. This study demonstrated the role of plant galactolipids as potential leads in the development of new drugs that alleviate the neuroinflammatory conditions associated with various diseases, such as Alzheimer's disease and Type 2 diabetes mellitus. [ABSTRACT FROM AUTHOR]

Simple Summary: Glioblastoma multiforme is a brain tumor with a very unfavorable prognosis, where the vast majority of patients do not survive a year after diagnosis. One line of research that may help in designing more successful therapeutic approaches is the synthesis and metabolism of arachidonic acid, which is then converted into a large number of different lipid mediators, including prostaglandins and leukotrienes (by cyclooxygenases and lipoxygenases, respectively). In this paper, we discuss the synthesis of arachidonic acid in glioblastoma multiforme tumors as well as the significance of lipid mediators synthesized from arachidonic acid, which can increase the proliferation of glioblastoma multiforme cancer cells, cause angiogenesis, inhibit the anti-tumor response of the immune system, and be responsible for resistance to treatment. Glioblastoma multiforme (GBM) is one of the most aggressive gliomas. New and more effective therapeutic approaches are being sought based on studies of the various mechanisms of GBM tumorigenesis, including the synthesis and metabolism of arachidonic acid (ARA), an omega-6 polyunsaturated fatty acid (PUFA). PubMed, GEPIA, and the transcriptomics analysis carried out by Seifert et al. were used in writing this paper. In this paper, we discuss in detail the biosynthesis of this acid in GBM tumors, with a special focus on certain enzymes: fatty acid desaturase (FADS)1, FADS2, and elongation of long-chain fatty acids family member 5 (ELOVL5). We also discuss ARA metabolism, particularly its release from cell membrane phospholipids by phospholipase A2 (cPLA2, iPLA2, and sPLA2) and its processing by cyclooxygenases (COX-1 and COX-2), lipoxygenases (5-LOX, 12-LOX, 15-LOX-1, and 15-LOX-2), and cytochrome P450. Next, we discuss the significance of lipid mediators synthesized from ARA in GBM cancer processes, including prostaglandins (PGE2, PGD2, and 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2)), thromboxane A2 (TxA2), oxo-eicosatetraenoic acids, leukotrienes (LTB4, LTC4, LTD4, and LTE4), lipoxins, and many others. These lipid mediators can increase the proliferation of GBM cancer cells, cause angiogenesis, inhibit the anti-tumor response of the immune system, and be responsible for resistance to treatment. [ABSTRACT FROM AUTHOR]

Coronavirus disease 2019 (COVID-19) is characterized by a broad spectrum of clinical symptoms. After acute infection, some subjects develop a post-COVID-19 syndrome known as long-COVID. This study aims to recognize the molecular and functional mechanisms that occur in COVID-19 and long-COVID patients and identify useful biomarkers for the management of patients with COVID-19 and long-COVID. Here, we profiled the response to COVID-19 by performing a proteomic analysis of lymphocytes isolated from patients. We identified significant changes in proteins involved in iron metabolism using different biochemical analyses, considering ceruloplasmin (Cp), transferrin (Tf), hemopexin (HPX), lipocalin 2 (LCN2), and superoxide dismutase 1 (SOD1). Moreover, our results show an activation of 5-lipoxygenase (5-LOX) in COVID-19 and in long-COVID possibly through an iron-dependent post-translational mechanism. Furthermore, this work defines leukotriene B4 (LTB4) and lipocalin 2 (LCN2) as possible markers of COVID-19 and long-COVID and suggests novel opportunities for prevention and treatment. [ABSTRACT FROM AUTHOR]

Inflammation is a complicated disorder that is produced as a result of consecutive processes. 5-LOX (5-lipoxygenase) is accountable for various inflammation mediators and leukotrienes synthesis, and its inhibition is the target of anti-inflammation therapeutics. Fungi have acquired enormous attentiveness because of their capability to biosynthesize novel bio-metabolites that reveal diversified bio-activities. A new tetracyclic triterpenoid, integracide L (1), along with integracides B (2) and F (3), were separated from Mentha longifolia-associated Fusarium sp. (FS No. MAR2014). Their structures were verified utilizing varied spectral analyses. The isolated metabolites (1–3), alongside the earlier reported integracides G (4), H (5), and J (6), were inspected for 5-LOX inhibition capacity. Interestingly, 1–6 possessed marked 5-LOX inhibition potentials with IC50s ranging from 1.18 to 3.97 μM compared to zileuton (IC50 1.17 µM). Additionally, molecular docking was executed to examine the interaction among these metabolites and 5-LOX, as well as to validate the in vitro findings. The docking study revealed their inhibitory activity interactions in the binding pocket. These findings highlighted the potential of integracides as lead metabolites for anti-inflammation drug discovery. [ABSTRACT FROM AUTHOR]

This mini-review addresses lipoxygenases and receptors for leukotrienes in hematological malignancies. Potential novel biomarkers and drug targets in leukemia and B-cell lymphoma are discussed. • B-cell chronic lymphocytic leukemia and B-cell lymphoma have high expression of 5-lipoxygenase. • Inhibition of the 5-lipoxygenase pathway or leukotriene B 4 receptor might inhibit the migration of malignant B cells. • Chronic myeloid leukemia cells possess high leukotriene C 4 synthase activity. • Hodgkin Reed-Sternberg cells express 15-lipoxygenase and cysteinyl-leukotriene receptor 1. • Potential novel biomarkers and drug targets in hematological malignancies are discussed. [ABSTRACT FROM AUTHOR]

Human 5-lipoxygenase (5-LO) is the key enzyme in the biosynthesis of leukotrienes, mediators of the innate immune system that also play an important role in inflammatory diseases and cancer. In this study, we present compounds, containing a Michael-reactive cyanoacrylate moiety as potent inhibitors of 5-LO. Representatives of the tyrosine kinase inhibitor family called tyrphostins, structurally related to known 5-LO inhibitors, were screened for their 5-LO inhibitory properties using recombinant human 5-LO, intact human PMNL (polymorphonuclear leukocytes), and PMNL homogenates. Their mode of action was characterized by the addition of glutathione, using a fourfold cysteine 5-LO mutant and mass spectrometry analysis. SAR studies revealed several members of the tyrphostin family containing a Michael-reactive cyanoacrylate to efficiently inhibit 5-LO. We identified degrasyn (IC50 0.11 µM), tyrphostin A9 (IC50 0.8 µM), AG879 (IC50 78 nM), and AG556 (IC50 64 nM) as potent 5-LO inhibitors. Mass spectrometry analysis revealed that degrasyn and AG556 covalently bound to up to four cysteines, including C416 and/or C418 which surround the substrate entry site. Furthermore, the 5-LO inhibitory effect of degrasyn was remarkably impaired by the addition of glutathione or by the mutation of cysteines to serines at the surface of 5-LO. We successfully identified several tyrphostins as potent inhibitors of human 5-LO. Degrasyn and AG556 were able to covalently bind to 5-LO via their cyanoacrylate moiety. This provides a promising mechanism for targeting 5-LO by Michael acceptors, leading to new therapeutic opportunities in the field of inflammation and cancer. [ABSTRACT FROM AUTHOR]

Arachidonic acid (AA) plays a critical role in inflammatory regulation and secondary injury after spinal cord injury (SCI). However, the overall AA metabolism profile in the acute phase of SCI remains elusive. Here we quantified AA metabolomics by High Performance Liquid Chromatography−Tandem Mass Spectrometry-Based Method (LC−MS/MS) using spinal cord tissue collected at 4 h, 24 h and 48 h after contusive SCI in rats. Remarkably, Prostaglandin E2 (PGE2) and Leukotriene B4 (LTB4) were significantly increased throughout the acute SCI. Cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX), the key enzymes involved in the production of PGE2 and LTB4, were elevated in the lesioned spinal cord tissue, validated by both western blot and immunofluorecnce. The spatial-temporal changes of COX-2 and 5-LOX mainly occurs in neurons both in epicenter and rostral and caudal spinal cord segments after SCI. Our study sheds light on the dynamic microenvironment changes in acute SCI by characterizing the profile of AA metabolism. The COX-2 and 5-LOX may be promising therapeutic target for SCI. [Display omitted] • Quantitative arachidonic acid metabolomics profiles based on LC-MS/MS were characterized in the acute spinal cord injury. • Prostaglandin E2 (PGE2) and Leukotriene B4 (LTB4) increased significantly after spinal cord injury. • Cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) are the key mediators in the acute spinal cord injury. [ABSTRACT FROM AUTHOR]

As innate immune cells of the central nervous system (CNS), microglia are involved in the physiological processes of the CNS, including neural development and maintenance of homeostasis, and in the occurrence and development of most CNS diseases. Lipoxygenases (LOXs) are a family of non-heme, iron-containing enzymes that generate lipid mediators that regulate cellular inflammation by catalyzing the oxidation of polyunsaturated fatty acids. Many previous studies have demonstrated the indispensable role of the LOX pathway in microglia-mediated neuroinflammation, especially the 5-LOX and 12/15-LOX pathways. Emerging evidence indicates that the LOX pathway is also implicated in physiological processes, such as synaptic pruning and synaptic phagocytosis mediated by microglia, and that deficiency can contribute to neurodevelopmental disorders. The present review summarizes the impact of the LOX pathway on microglia-related physiological and pathological processes in the CNS and describes the potential for inhibition of the LOX pathway as a future strategy for the treatment of CNS diseases. [ABSTRACT FROM AUTHOR]

Introduction: Previous work of our group showed that lipoxygenase (LOX) pathways become activated upon surgical manipulation of the bowel wall and revealed a beneficial immune modulating role of the LOX-derived anti-inflammatory mediator protectin DX in postoperative ileus (POI). While we found a particular role of 12/15-LOX in the anti-inflammatory LOX action during POI, the role of 5-LOX, which produces the pro-inflammatory leukotriene B4 (LTB4), remained unknown. The purpose of this study was to investigate the role of 5-LOX within the pathogenesis of POI in a mouse model. Methods: POI was induced by intestinal manipulation (IM) of the small bowel in C57BL/6, 5-LOX−/−, and CX3CR1GFP/+. Mice were either treated with a vehicle or with the synthetic 5-LOX antagonist zileuton or were left untreated. Cellular localization of 5-LOX and LTB4 release were visualized by immunofluorescence or ELISA, respectively. POI severity was quantified by gastrointestinal transit (GIT) and leukocyte extravasation into the muscularis externa (ME) by immunohistochemistry. Results: 5-LOX expression was detected 24 h after IM within infiltrating leukocytes in the ME. LTB4 levels increased during POI in wild type but not in 5-LOX−/− after IM. POI was ameliorated in 5-LOX−/− as shown by decreased leukocyte numbers and normalized GIT. Zileuton normalized the postoperative GIT and reduced the numbers of infiltrating leukocytes into the ME. Discussion/Conclusion: Our data demonstrate that 5-LOX and its metabolite LTB4 play a crucial role in POI. Genetic deficiency of 5-LOX and pharmacological antagonism by zileuton protected mice from POI. 5-LOX antagonism might be a promising target for prevention of POI in surgical patients. [ABSTRACT FROM AUTHOR]

Cecropia pachystachya Tréc., popularly known as embaúba, belongs to the Cecropiaceae family and is used by the native population in the treatment of bronchitis, asthma, high blood pressure, fever, and as a diuretic. The pharmacological actions including anti-inflammatory, antioxidant, cardiotonic and sedative were previously reported. The objective of this study was to (1) isolate and identify bioactive compounds extracted from the ethanolic extract of C. pachystachya roots (ERCP), as well as (2) verify the affinity of these metabolites with the enzymes 5-lipoxygenase (5-LOX) and α-1-antitrypsin through in silico tests. Isolation and/or identification were performed using GC-MS, HPLC, Infrared (IR), and nuclear magnetic resonance (NMR) techniques. After isolation and identification of the active compounds, these substances were subjected to the in silico investigation that proceeded by performing PreADMET simulations and molecular docking calculations. The bioactive compounds identified were 1-(+)-ascorbic acid 2,6-dihexadecanoate, ethyl hexadecanoate, ethyl (9E,12E)-octadec-9,12-dienoate, ethyl (Z)-octadec-9-enoate and ethyl octadecanoate by GC-MS; chlorogenic acid, catechin, epicatechin, syringaldehyde by HPLC; β-sitosterol, sitostenone, beccaridiol, tormentic acid, lupeol, α- and β-amyrin by classical chromatography, IR, 1H and 13C NMR techniques. The ADMET (absorption, distribution, metabolism, excretion, and toxicity) properties were determined for each bioactive compound. Tormentic acid demonstrated a greater affinity for 5-LOX enzyme while sitostenone demonstrated a higher affinity for the α-1-antitrypsin enzyme. Our findings demonstrated a diverse range of secondary metabolites isolated from C. pachystachya that showed relevant interactions with the enzymes 5-LOX and α-1-antitrypsin. Thus, "embaúba" may be employed in in vivo experimental studies as a form of alternative treatment for chronic lung diseases. Abbreviations: ADT: Autodock Tools; BBB: Blood-brain barrier; CaCo2: Human colonic adenocarcinoma cells; CC: Classic/open Column; TLC: Thin Layer Chromatography; CD40: Differentiation Cluster 40; CENAUREMN: Centro Nordestino de Aplicação e Uso da Ressonância Magnética Nuclear; GC-MS: Gas Chromatography coupled to mass spectrometry; HPLC: High-Perfomance Liquid Chromatography; CYP2C9, CYP2C19, CYP2D6 and CYP3A4: Cytochrome P450 isoenzymes; COPD: Chronic Obstructive Pulmonary Disease; DRX-500: X-Ray Diffraction – 500; ERCP: Ethanolic extract of the roots of C. pachystachya; FAPEPI: Fundação de Amparo à Pesquisa do Piauí; HIA: Human Intestinal Absorption; IR: Infrared; Ki: Inhibition constant; 5-LOX: 5-Lipoxygenase; mM: miliMolar; nM: nanoMolar; OECD423: acute toxic class method; PDB: Protein Data Bank; P-gP: P-glycoprotein; PM2,5: Small inhalable particles 2,5; PPB: Plasm Protein Binding; PreADMET: Prediction Absorption, Distribution, Metabolization, Excretion and Toxicity; NMR: Nuclear Magnetic Resonance; +S9: with metabolic activation; -S9: no metabolic activation; SisGen: Sistema Nacional de Gestão de Patrimônio Genético e do Conhecimento Tradicional Associado; RT: Retention time; TA100: Ames test with TA100 cells line; TA1535: Ames test with cells of the TA1535 cell line; UESPI: State University of Piauí; V79: lung fibroblast cells; ΔG: Gibbs free energy (Kcal/mol); μM: microMolar. [ABSTRACT FROM AUTHOR]

Radiation-induced cutaneous ulcers are a challenging medical problem for patients receiving radiation therapy. The inhibition of cell senescence has been suggested as a prospective strategy to prevent radiation ulcers. However, there is no effective treatment for senescent cells in radiation ulcers. In this study, we investigated whether zileuton alleviated radiation-induced cutaneous ulcer by focusing on cell senescence. We demonstrate increased cell senescence and senescence-associated secretory phenotype (SASP) in irradiated dermal fibroblasts and skin tissue. The SASP secreted from senescent cells induces senescence in adjacent cells. In addition, 5-lipoxygenase (5-LO) expression increased in irradiated dermal fibroblasts and skin tissue, and SASP and cell senescence were regulated by 5-LO through p38 phosphorylation. Finally, the inhibition of 5-LO following treatment with zileuton inhibited SASP and mitigated radiation ulcers in animal models. Our results demonstrate that inhibition of SASP from senescent cells by zileuton can effectively mitigate radiation-induced cutaneous ulcers, indicating that inhibition of 5-LO might be a viable strategy for patients with this condition. [ABSTRACT FROM AUTHOR]

Lipoxygenases convert polyunsaturated fatty acids into biologically active metabolites such as inflammatory mediators—prostaglandins and leukotrienes. The inhibition of lipoxygenases is increasingly employed in the treatment of cancer. We evaluated the anticancer potential of two novel 5-lipoxygenase inhibitors, named CarbZDNaph and CarbZDChin, which are analogues of the commercially available inhibitor Rev-5901. The in vitro segment of this study was conducted on a mouse colorectal carcinoma cell line—CT26CL25. For an in vivo model, we induced tumors in BALB/c mice by the implantation of CT26CL25 cells, and we treated the animals with potential inhibitors. A 48 h treatment resulted in diminished cell viability. Calculated IC50 values (half-maximal inhibitory concentrations) were 25 μM, 15 μM and 30 μM for CarbZDNaph, CarbZDChin and Rev-5901, respectively. The detailed analysis of mechanism revealed an induction of caspase-dependent apoptosis and autophagy. In the presence of chloroquine, an autophagy inhibitor, we observed an increased mortality of cells, implying a cytoprotective role of autophagy. Our in vivo experiment reports tumor growth attenuation in animals treated with CarbZDChin. Compounds CarbZDNaph and Rev-5901 lacked an in vivo efficacy. The results presented in this study display a strong effect of compound CarbZDChin on malignant cell growth. Having in mind the important role of inflammation in cancer development, these results have a significant impact and are worthy of further evaluation. [ABSTRACT FROM AUTHOR]

Cephalopod cuttlefish, Sepia pharaonis, has been considered as a commercially important resource, which is widely regarded as nutritious food in the southwest of Indian and Mediterranean coasts. Chemical analysis of the crude extract of S. pharaonis resulted in the isolation of an undescribed 2H‐benzochromenone, pharachromenone, which was characterized as methyl‐2″‐(7‐hydroxy‐4‐(5′‐methylpent‐5′‐en‐1′‐yl‐oxy‐methyl)‐2‐oxo‐2H‐benzo[h]chromen‐5‐yl‐methyl)‐butanoate by mass and nuclear magnetic resonance spectral experiments. Pharachromenone revealed effective biopotency against 5‐lipoxygenase (IC50 1.85 mM) and cyclooxygenase‐2 (IC50 0.52 mM) than that displayed by nonsteroidal anti‐inflammatory drug ibuprofen (IC50 4.36 mM, p <.05). Promising antioxidant property for pharachromenone (IC50 1.42–1.61 mM) compared with those exhibited by antioxidative agents butylated hydroxyl anisole (BHA) and α‐tocopherol (IC50 1.40–1.90 mM) could conceivably validate its dual inhibition potential against 5‐lipoxygenase and cyclooxygenase‐2. Greater electronic parameters, lesser steric bulkiness, along with acceptable lipophilic–hydrophobic balance significantly contributed toward its promising anti‐inflammatory activities. Molecular docking studies showing significantly greater inhibition constant (Ki) 8.24 nM and binding energy (−11.03 kcal/mol) of pharachromenone than the standard ibuprofen (Ki 4.65 μM, binding energy −7.27 kcal/mol) at the binding site of 5‐lipoxygenase recognized its noncompetitive binding, which could describe the promising anti‐inflammatory potential. Pharachromenone could be developed as a functional food component against oxidative stress‐related inflammatory disorders. Practical applications: The cuttlefish Sepia pharaonis (family Sepiidae) comprises a major share in the global fishery sector due to its culinary delicacy and nutritionally valued high‐quality meat. Furthermore, cephalopod mollusks are gaining pharmaceutical acceptance as resources to derive bioactive compounds with therapeutic significance. Bioassay‐guided chromatographic fractionation of crude extract of S. pharaonis could result in the isolation of a 2H‐benzochromenone derivative, pharachromenone exhibiting potent antioxidant and anti‐inflammatory properties. This study recognized the therapeutic potential of a marine cuttlefish‐originated food constituent against inflammatory conditions, and could be anticipated as a high‐value functional food lead to minimize oxidative stress‐related inflammatory disorders. [ABSTRACT FROM AUTHOR]

M1 microglia induce neuroinflammation-related neuronal death in animal models of spontaneous subarachnoid haemorrhage. Zileuton is a 5-lipoxygenase inhibitor that reduces the levels of downstream pro-inflammatory cytokines. This study aimed to investigate whether zileuton inhibits microglial activation and describe its underlying mechanisms. BV-2 cells were exposed to 1 mg/mL haemolysate for 30 min, followed by treatment with different concentrations (5, 10, 15, or 20 μM) of zileuton for 24 h. The cells were then assessed for viability, polarisation, and protein expression levels. Haemolysate increases the viability of BV-2 cells and induces M1 polarisation. Subsequent exposure to high concentrations of zileuton decreased the viability of BV-2 cells, shifted the polarisation to the M2 phenotype, suppressed the expression of 5-lipoxygenase, decreased tumour necrosis factor α levels, and increased interleukin-10 levels. Furthermore, high concentrations of zileuton suppressed the expression of myeloid differentiation primary response protein 88 and reduced the phosphorylated-nuclear factor-kappa B (NF-kB)/NF-kB ratio. Therefore, phenotype reversal from M1 to M2 is a possible mechanism by which zileuton attenuates haemolysate-induced neuroinflammation after spontaneous subarachnoid haemorrhage. [ABSTRACT FROM AUTHOR]

Natural forms of vitamin E comprise four tocopherols and four tocotrienols. During the last twenty years, there have been breakthroughs in our understanding of vitamin E metabolism and biological activities of vitamin E metabolites. Research has established that tocopherols and tocotrienols are metabolized via ω-hydroxylase (CYP4F2)-initiated side chain oxidation to form 13′-hydroxychromanol and 13′-carobyxychromanol (13′-COOH). 13′-COOHs are further metabolized via β-oxidation and sulfation to intermediate carboxychromanols, terminal metabolite carboxyethyl-hydroxychroman (CEHC), and sulfated analogs. Animal and human studies show that γ-, δ-tocopherol and tocotrienols are more extensively metabolized than α-tocopherol (αT), as indicated by higher formation of CEHCs and 13′-COOHs from non-αT forms than those from αT. 13′-COOHs are shown to be inhibitors of cyclooxygenase-1/-2 and 5-lipoxygenase and much stronger than CEHCs for these activities. 13′-COOHs inhibit cancer cell growth, modulate cellular lipids and activate peroxisome proliferator-activated receptor-γ and pregnane X receptor. Consistent with mechanistic findings, αT-13′-COOH or δTE-13′-COOH, respective metabolites of αT or δ-tocotrienol, show anti-inflammatory and cancer-preventive effects, modulates the gut microbiota and prevents β-amyloid formation in mice. Therefore, 13′-COOHs are a new class of bioactive compounds with anti-inflammatory and anti-cancer activities and potentially capable of modulating lipid and drug metabolism. Based on the existing evidence, this author proposes that metabolites may contribute to disease-preventing effects of γ-, δ-tocopherol and tocotrienols. The role of metabolites in αT's actions may be somewhat limited considering controlled metabolism of αT because of its association with tocopherol-transport protein and less catabolism by CYP4F2 than other vitamin E forms. [Display omitted] • Vitamin E tocopherols and tocotrienols are metabolized by CYP4F2 to form metabolites including 13'-COOHs and CEHCs. • Gamma-, delta-tocopherols and tocotrienols are more extensively metabolized than alpha-tocopherol. • 13'-COOHs are inhibitors of cyclooxygenase-1/-2 and 5-lipoxygenase, inhibit cancer cell growth, and activate PPAR and PXR. • 13'-COOHs are capable of anti-inflammation, anti-cancer and modulating lipid and drug metabolism. • Metabolites may contribute to bioactivities of gamma- or delta-tocopherol and tocotrienols. [ABSTRACT FROM AUTHOR]

• 5-LO deletion leads to motor impairment and repetitive behavior in mice. • 5-LO deletion disrupts synapse levels in hippocampus and motor cortex of mice. • 5-LO interferes with CX3CR1 and CX3CL1 brain expression. • 5-LO deletion disrupts physiological neuron-glia interaction in the brain. Neural-immune interactions are related to the synapse plasticity and other dynamic processes in the nervous system. The absence or dysfunction of cellular/molecular elements from the immune system lead to impairments in the central and peripheral nervous system with behavior consequences such as cognitive, sensory, and locomotor deficits as well as social disabilities and anxiety disturbances. Cellular interactions between immune cells such as macrophages, microglia, and neutrophils with glial or neuronal cells have been of increasing interest over the last years. However, little is known about the role of immune-derived soluble factors in the context of homeostasis of the nervous system. Leukotrienes (LTs) are lipid mediators derived from the oxidation of arachidonic acid by 5-lipoxygenase (5-LO), and are classically involved in inflammation, allergies, and asthma. Here, we demonstrated that adult mice lacking 5-LO (5-LO−/−) showed motor deficits in rotarod test and increased repetitive behavior (marble burying test). These behavioral changes are accompanied by increased levels of synapse proteins (PSD95 and synaptophysin) at the motor cortex and hippocampus, but not with BDNF alterations. No changes in microglial cell density or morphology were seen in the brains of 5-LO−/− mice. Furthermore, expression of fractalkine receptor CX3CR1 was increased and of its ligand CX3CL1 was decreased in the cortex of 5-LO−/− mice. Here we provide evidence for the involvement of 5-LO products structuring synapses network with motor behavior consequences. We suggest that the absence of 5-LO products lead to modified microglial/neuron interaction, reducing microglial pruning. [ABSTRACT FROM AUTHOR]

Neutrophils are the most abundant leukocytes in circulation playing a key role in acute inflammation during microbial infections. Phagocytosis, one of the crucial defence mechanisms of neutrophils against pathogens, is amplified by chemotactic leukotriene (LT)B4, which is biosynthesized via 5‐lipoxygenase (5‐LOX). However, extensive liberation of LTB4 can be destructive by over‐intensifying the inflammatory process. While enzymatic biosynthesis of LTB4 is well characterized, less is known about molecular mechanisms that activate 5‐LOX and lead to LTB4 formation during host–pathogen interactions. Here, we investigated the ability of the common opportunistic fungal pathogen Candida albicans to induce LTB4 formation in neutrophils, and elucidated pathogen‐mediated drivers and cellular processes that activate this pathway. We revealed that C. albicans‐induced LTB4 biosynthesis requires both the morphological transition from yeast cells to hyphae and the expression of hyphae‐associated genes, as exclusively viable hyphae or yeast‐locked mutant cells expressing hyphae‐associated genes stimulated 5‐LOX by [Ca2+]i mobilization and p38 MAPK activation. LTB4 biosynthesis was orchestrated by synergistic activation of dectin‐1 and Toll‐like receptor 2, and corresponding signaling via SYK and MYD88, respectively. Conclusively, we report hyphae‐specific induction of LTB4 biosynthesis in human neutrophils. This highlights an expanding role of neutrophils during inflammatory processes in the response to C. albicans infections. [ABSTRACT FROM AUTHOR]

Objective: To explore the changes in the expression of hypoxia-inducible factor (HIF-1α) and 5-lipoxygenase(5-LOX)in chronic nasal diseases and their relationship with the severity of the disease. Methods: From July 2019 to November 2020, 75 patients with chronic rhinopathy admitted to our hospital were selected as the research subjects; among them, 25 were nasal polyps, 25 were allergic rhinitis, and 25 were sinusitis; 30 cases of transnasal septum were selected during the same period. The inferior turbinate mucosal tissue of patients undergoing inferior turbinoplasty with curvature correction was set as the control group. Compare the levels of hypoxia-inducible factor and 5-lipoxygenase protein and m RNA in the four groups of patients; and analyze the correlation between HIF-1α and 5-LOX in different nasal diseases. Results: The expression levels of HIF-1α and 5-LOX in the nasal polyp group, allergic rhinitis group, and sinusitis group were higher than those in the control group(P<0.05); HIF-1α in the nasal polyp group, allergic rhinitis group, and sinusitis group The expression level of 5-LOX was not statistically significant (P>0.05). The expression levels of HIF-1α and5-LOX m RNA in the nasal polyp group, allergic rhinitis group, and sinusitis group were higher than those in the control group (P<0.05); HIF-in the nasal polyp group, allergic rhinitis group, and sinusitis group The expression levels of 1α and 5-LOX m RNA were not statistically significant(P>0.05). Parman correlation analysis showed that HIF-1α protein expression was positively correlated with5-LOX protein expression in different nasal diseases (P<0.05). Conclusion: In chronic nasal diseases(nasal polyps, allergic rhinitis, sinusitis), the expression levels of HIF-1α and 5-LOX are significantly increased, and they may promote and influence each other in the development of chronic diseases. [ABSTRACT FROM AUTHOR]

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, known as coronavirus disease 2019 (COVID-19) causes cytokine release syndrome (CRS), leading to acute respiratory distress syndrome (ARDS), acute kidney and cardiac injury, liver dysfunction, and multiorgan failure. Although several studies have discussed the role of 5-lipoxygenase (5-LOX) in viral infections, such as influenzae and SARS, it remains unexplored in the pathophysiology of COVID-19. 5-LOX acts on free arachidonic acid (AA) to form proinflammatory leukotrienes (LTs). Of note, numerous cells involved with COVID-19 (e.g., inflammatory and smooth muscle cells, platelets, and vascular endothelium) widely express leukotriene receptors. Moreover, 5-LOX metabolites induce the release of cytokines (e.g., tumour necrosis factor-α [TNF-α], interleukin-1α [IL-1α], and interleukin-1β [IL-1β]) and express tissue factor on cell membranes and activate plasmin. Since macrophages, monocytes, neutrophils, and eosinophils can express lipoxygenases, activation of 5-LOX and the subsequent release of LTs may contribute to the severity of COVID-19. This review sheds light on the potential implications of 5-LOX in SARS-CoV-2-mediated infection and the anticipated therapeutic role of 5-LOX inhibitors. [ABSTRACT FROM AUTHOR]

Objective: To explore the changes in the expression of hypoxia-inducible factor (HIF-1α) and 5-lipoxygenase (5-LOX) in chronic nasal diseases and their relationship with the severity of the disease. Methods: From July 2019 to November 2020, 75 patients with chronic rhinopathy admitted to our hospital were selected as the research subjects; among them, 25 were nasal polyps, 25 were allergic rhinitis, and 25 were sinusitis; 30 cases of transnasal septum were selected during the same period. The inferior turbinate mucosal tissue of patients undergoing inferior turbinoplasty with curvature correction was set as the control group. Compare the levels of hypoxia-inducible factor and 5-lipoxygenase protein and mRNA in the four groups of patients; and analyze the correlation between HIF-1α and 5-LOX in different nasal diseases. Results: The expression levels of HIF-1α and 5-LOX in the nasal polyp group, allergic rhinitis group, and sinusitis group were higher than those in the control group (P<0.05); HIF-1α in the nasal polyp group, allergic rhinitis group, and sinusitis group The expression level of 5-LOX was not statistically significant (P>0.05). The expression levels of HIF-1α and 5-LOX mRNA in the nasal polyp group, allergic rhinitis group, and sinusitis group were higher than those in the control group (P<0.05); HIF- in the nasal polyp group, allergic rhinitis group, and sinusitis group The expression levels of 1α and 5-LOX mRNA were not statistically significant (P>0.05). Parman correlation analysis showed that HIF-1α protein expression was positively correlated with 5-LOX protein expression in different nasal diseases (P<0.05). Conclusion: In chronic nasal diseases (nasal polyps, allergic rhinitis, sinusitis), the expression levels of HIF-1α and 5-LOX are significantly increased, and they may promote and influence each other in the development of chronic diseases. [ABSTRACT FROM AUTHOR]

Introduction: The leukotriene pathway may be implicated in the induction of virus-induced inflammation. Respiratory epithelial cells may express low levels of 5-lipoxygenase (5-LO) and release leukotrienes (LTs) C4, D4, and E4, upon exposure to viruses or other stimuli. Enhanced expression of 5-LO pathway proteins after rhinovirus (RV) infection has previously been described. We hypothesized that anti-leukotriene treatment of epithelial cells, with or without exposure to RV-infected peripheral blood mononuclear cells (PBMCs)-conditioned media, may inhibit RV-induced up-regulation of inflammatory cytokines. Methods: PBMCs from a healthy donor were exposed to RV1B and supernatants were harvested at 48 h post infection. BEAS-2B cells were infected with RV, with or without conditioning with the PBMC supernatant. Treatment with anti-LT agents was performed either on both PBMCs and BEAS-2B or at the bronchial epithelial level only, with varying concentrations of montelukast (CysLT receptor antagonist) or MK-886 [FLAP(5-lipoxygenase-activating-protein) inhibitor]. Evaluation of the inflammatory cytokines IL-8, RANTES, IL-11, IL-6, and IP-10 was performed using ELISA. Results: Our results show that anti-LT treatment of RV-infected bronchial epithelial cells suppresses epithelial RV-mediated cytokine production, independent of conditioning. Conclusions: This observation may represent an indirect mode of action of the anti-leukotrienes in virus-induced asthma. [ABSTRACT FROM AUTHOR]

The usage of natural sources like lichen extracts and their metabolites as anti-inflammatory agents is well known for ages. Based on the data of the folklore and documented books, researchers tested lichens and their products for antiinflammatory properties and they identified many therapeutic agents used to diagnosis acute and chronic inflammation with lesser side effects. In this study, we aimed to examine the acetone extract of Cladonia corniculata(AE)and its metabolites for in vitro anti-inflammatory and anti-gout effects. Through chemical investigation, we have successfully isolated and identified three known dibenzofurans, namely alectosarmentin 1, porphyrilic acid 2, and strepsilin 3 from the AE. All isolated dibenzofurans1-3 showed prominent inhibition of cyclooxygenase enzymes, whereas compounds 1 and 2 exhibited noticeable inhibition of 5-lipoxygenase enzyme. Only compound 2 showed significant inhibition of xanthine oxidase enzyme with an IC50 value of 80.17±0.66 μg/mL, while standard drug allopurinol with 9.10±0.64 μg/mL. The results indicate that C. corniculatacan be a favourable natural source for the treatment of inflammation and gout and these actions are linked to the natural active dibenzofurans1-3. [ABSTRACT FROM AUTHOR]

Sepsis rapidly contributed to multiorgan failure affecting most commonly of the cardiovascular and respiratory systems and yet there were no effective therapies. The current study aimed at providing evidence on the cardioprotection of suppression of 5-Lipoxygenase (5-Lox) and identifying the possible mechanism in the mouse model of sepsis. The cecal ligation-perforation (CLP) model was applied to C57BL/6 wild-type (WT) and 5-Lox deficient (5-Lox−/−) mice to induce sepsis. 5-Lox expression was up-regulated in mouse myocardium and leukotriene B4 (LTB4) level was increased in serum after sepsis. Subsequently, we utilized a recombinant adenoviral expression vector (rAAV9) to overexpress Alox5 gene in adult mice. Compared to WT mice, 5-Lox overexpression accelerated CLP-induced myocardial injury and cardiac dysfunction. Oppositely, 5-Lox deficiency offered protection against myocardial injury in a mouse model of sepsis and attenuated sepsis-mediated inflammation, oxidative stress and apoptosis in the mouse heart. Mechanically, 5-Lox promoted LTB4 production, which in turn contributed to the activation of leukotriene B4 receptor 1 (BLT1)/interleukin-12p35 (IL-12p35) pathway and enhanced M1 macrophage polarization. However, the suppression of BLT1 by either gene mutation or antagonist U75302 significantly inhibited the adverse effect of 5-Lox in sepsis. Further study demonstrated that pharmacological inhibition of 5-Lox prevented CLP-induced septic cardiomyopathy (SCM). Our study identified 5-Lox exacerbated sepsis-associated myocardial injury through activation of LTB4 production and promoting BLT1/IL-12p35 pathway. Hence, inhibition of 5-Lox may be a potential candidate strategy for septic cardiac dysfunction treatment. An illustrative summary. Following CLP, 5-Lox promotes the activation of LTB4-BLT1-IL-12p35 pathway in heart. Genetic and pharmacological inhibition of 5-Lox blunt the cardiac inflammatory responses (inflammatory cells infiltration and cytokine expression), improve survival and preserve cardiac function (higher LVEF at 24 h post-CLP). Blockage of BLT1 abolishes 5-Lox mediated myocardial injury.▪ •.Inhibition of 5-lipoxygenase (5-Lox) alleviated septic cardiomyopathy (SCM). • 5-Lox promoted activation of BLT1/IL-12p3. • 5-Lox may become a potential target for pharmacological or dietary interventions to decrease sepsis-related cardiac injury. [ABSTRACT FROM AUTHOR]

The miRNA biogenesis is tightly regulated to avoid dysfunction and consequent disease development. Here, we describe modulation of miRNA processing as a novel noncanonical function of the 5‐lipoxygenase (5‐LO) enzyme in monocytic cells. In differentiated Mono Mac 6 (MM6) cells, we found an in situ interaction of 5‐LO with Dicer, a key enzyme in miRNA biogenesis. RNA sequencing of small noncoding RNAs revealed a functional impact, knockout of 5‐LO altered the expression profile of several miRNAs. Effects of 5‐LO could be observed at two levels. qPCR analyses thus indicated that (a) 5‐LO promotes the transcription of the evolutionarily conserved miR‐99b/let‐7e/miR‐125a cluster and (b) the 5‐LO‐Dicer interaction downregulates the processing of pre‐let‐7e, resulting in an increase in miR‐125a and miR‐99b levels by 5‐LO without concomitant changes in let‐7e levels in differentiated MM6 cells. Our observations suggest that 5‐LO regulates the miRNA profile by modulating the Dicer‐mediated processing of distinct pre‐miRNAs. 5‐LO inhibits the formation of let‐7e which is a well‐known inducer of cell differentiation, but promotes the generation of miR‐99b and miR‐125a known to induce cell proliferation and the maintenance of leukemic stem cell functions. [ABSTRACT FROM AUTHOR]

Background and Aim: 5‐Lipoxygenase has been reported to enhance cell proliferation, migration, and invasion. Epithelial–mesenchymal transition is considered an important process for tumor metastasis and invasion. Methods: The 5‐lipoxygenase expression levels and the prognoses in patients with gastric cancer were evaluated by immunohistochemistry and by the log‐rank test on Kaplan–Meier curves. We established 5‐lipoxygenase‐overexpressed and 5‐lipoxygenase‐silenced gastric cancer cells and measured migration, invasion, and epithelial–mesenchymal transition makers to examine the role of 5‐lipoxygenase in gastric cancer in vitro. In vivo, 5‐lipoxygenase‐overexpressed gastric cancer cells were administered into mice by subcutaneous injection, intraperitoneal injection or splenic intravenous injection to study the proliferation or metastasis of 5‐lipoxygenase in mice. Using the extracellular signal‐regulated kinase pathway inhibitor U0126 and activator tumor growth factor‐β, we investigated the mechanism of epithelial–mesenchymal transition induced by 5‐lipoxygenase in gastric cancer cells. Results: 5‐Lipoxygenase was upregulated in gastric cancer tissues and was related to poor overall survival in gastric cancer patients. 5‐Lipoxygenase promoted gastric cancer cell proliferation, migration, and invasion and induced the process of epithelial–mesenchymal transition in gastric cancer cells. In the nude mouse model, mice with gastric cancer tumors overexpressing 5‐LOX had a faster tumor growth rate and more severe abdominal and liver metastases than the control group. Inhibition of extracellular signal‐regulated kinase signaling by U0126 or activation by tumor growth factor‐β neutralized the effect of 5‐LOX overexpression or silencing on epithelial–mesenchymal transition. Conclusion: 5‐Lipoxygenase promotes epithelial–mesenchymal transition in gastric cancer by activating the extracellular signal‐regulated kinase signaling pathway. [ABSTRACT FROM AUTHOR]

5‐Lipoxygenase (5‐LO) is the initial enzyme in the biosynthesis of leukotrienes, which are mediators involved in pathophysiological conditions such as asthma and certain cancer types. Knowledge of proteins involved in 5‐LO pathway regulation, including gene regulatory proteins, is needed to evaluate all options for therapeutic intervention in these diseases. Here, we present a mass spectrometric screening of ALOX5 promoter‐interacting proteins, obtained by DNA pulldown and label‐free quantitative mass spectrometry. Protein preparations from myeloid and B‐lymphocytic cell lines were screened for promoter DNA interactors. Through statistical analysis, 66 proteins were identified as specific ALOX5 promotor binding proteins. Among those, the 15 most likely candidates for a prominent role in ALOX5 gene regulation are the known ALOX5 interactors Sp1 and Sp3, the related factor Sp2, two Krüppel‐like factors (KLF13 and KLF16) and six other zinc finger proteins (MAZ, PRDM10, VEZF1, ZBTB7A, ZNF281 and ZNF579). Intriguingly, we also identified two helicases (BLM and DHX36) and the proteins hnRNPD and hnRNPK, which are, together with the protein MAZ, known to interact with DNA G‐quadruplex structures. As G‐quadruplexes are implicated in gene regulation, spectroscopic and antibody‐based methods were used to confirm their presence within the GC‐rich sequence of the ALOX5 promoter. In summary, we have systematically characterized the interactome of the ALOX5 promoter, identifying several zinc finger proteins as novel potential ALOX5 gene regulators. Further, we have shown that the ALOX5 promoter can form DNA G‐quadruplex structures, which may play a functional role in ALOX5 gene regulation. [ABSTRACT FROM AUTHOR]

Inflammation secondary to tissue injuries serves as a double-edged sword that determines the prognosis of tissue repair. As one of the most important enzymes controlling the inflammation process by producing leukotrienes, 5-lipoxygenase (5-LOX, also called 5-LO) has been one of the therapeutic targets in regulating inflammation for a long time. Although a large number of 5-LOX inhibitors have been explored, only a few of them can be applied clinically. Surprisingly, phosphorylation of 5-LOX reveals great significance in regulating the subcellular localization of 5-LOX, which has proven to be an important mechanism underlying the enzymatic activities of 5-LOX. There are at least three phosphorylation sites in 5-LOX jointly to determine the final inflammatory outcomes, and adjustment of phosphorylation of 5-LOX at different phosphorylation sites brings hope to provide an unrecognized means to regulate inflammation. The present review intends to shed more lights into the set-point-like mechanisms of phosphorylation of 5-LOX and its possible clinical application by summarizing the biological properties of 5-LOX, the relationship of 5-LOX with neurodegenerative diseases and brain injuries, the phosphorylation of 5-LOX at different sites, the regulatory effects and mechanisms of phosphorylated 5-LOX upon inflammation, as well as the potential anti-inflammatory application through balancing the phosphorylation-depended set-point. [ABSTRACT FROM AUTHOR]

Massive neutrophil infiltration is an early key event in infectious inflammation, accompanied by chemotactic leukotriene (LT)B4 generation. LTB4 biosynthesis is mediated by 5-lipoxygenase (5-LOX), but which pathogenic factors cause 5-LOX activation during bacterial infections is elusive. Here, we reveal staphylococcal exotoxins as 5-LOX activators. Conditioned medium of wild-type Staphylococcus aureus but not of exotoxin-deficient strains induced 5-LOX activation in transfected HEK293 cells. Two different staphylococcal exotoxins mimicked the effects of S. aureus-conditioned medium: (1) the pore-forming toxin α-hemolysin and (2) amphipathic α-helical phenol-soluble modulin (PSM) peptides. Interestingly, in human neutrophils, 5-LOX activation was exclusively evoked by PSMs, which was prevented by the selective FPR2/ALX receptor antagonist WRW4. 5-LOX activation by PSMs was confirmed in vivo as LT formation in infected paws of mice was impaired in response to PSM-deficient S. aureus. Conclusively, exotoxins from S. aureus are potent pathogenic factors that activate 5-LOX and induce LT formation in neutrophils. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is the main cause of septic arthritis in humans, a disease associated with high morbidity and mortality. Inflammation triggered in response to infection is fundamental to control bacterial growth but may cause permanent tissue damage. Here, we evaluated the role of Lipoxin A4 (LXA4) in S aureus-induced arthritis in mice. Septic arthritis was induced by S aureus injection into tibiofemoral joints. At different time points, we evaluated cell recruitment and bacterial load in the joint, the production of pro-inflammatory molecules, and LXA4 in inflamed tissue and analyzed joint damage and dysfunction. LXA4 was investigated using genetically modified mice or by pharmacological blockade of its synthesis and receptor. CD11c+ cells were evaluated in lymph nodes by confocal microscopy and flow cytometry and dendritic cell chemotaxis using the Boyden chamber. Absence or pharmacological blockade of 5-lipoxygenase (5-LO) reduced joint inflammation and dysfunction and was associated with better control of infection at 4 to 7 days after the infection. There was an increase in LXA4 in joints of S aureus-infected mice and administration of LXA4 reversed the phenotype in 5-LO-/- mice. Blockade or absence of the LXA4 receptor FPR2 has a phenotype similar to 5-LO-/- mice. Mechanistically, LXA4 appeared to control migration and function of dendritic cells, cells shown to be crucial for adequate protective responses in the model. Thus, after the first days of infection when symptoms become evident therapies that inhibit LXA4 synthesis or action could be useful for treatment of S aureus-induced arthritis. [ABSTRACT FROM AUTHOR]

People suffering from malnutrition show compromised levels of ω-6 fatty acid and malnutrition is frequently observed among visceral leishmaniasis (VL) patients as disease inflicts primarily the socioeconomic destitute communities. Dietary linoleic acid (LA, 18:2; ω-6 fatty acid) is the principal source of essential fatty acid and its derivatives i.e. eicosanoids possess immune-modulatory activities. However, its role in VL is not yet established. LA was measured in VL human subjects (serum) as well as in Leishmania (L.) donovani infected hamsters (serum and visceral organs). Organ-specific mRNA expressions of various enzymes of the LA metabolic pathway were measured in visceral organs of infected hamsters. Our findings showed a decrease in the concentrations of LA in the serum samples of VL patients, suggesting malnutrition among these patients. However, in L. donovani infected hamsters, its level was not altered in the early infection (15 days) and then increased at late infection (60 days). Importantly, the supplementation of LA restored the Th-1 type of immune response and significantly reduced the parasite load within infected macrophages in vitro. This protective response of LA was mediated through 5-lipoxygenase pathway not via the cyclooxygenase pathway. Preventive usage of LA to mϕ followed by L. donovani infection also showed the strengthening of Th-1 immune response and significantly fewer parasite loads. Our findings demonstrate the protective role of LA in the containment of the parasite load. Incorporating LA rich oils in daily food habits across highly inflicted regions may be a significant advancement towards the eradication of the disease. Image 1 • Low levels of linoleic acid (LA) in visceral leishmaniasis patients. • LA supplementation restored the Th-1 type of immune response in vitro. • LA supplementation reduced the parasite load within infected macrophages. • Protective response of LA was mediated via 5-lipoxygenase pathway not COX pathway. [ABSTRACT FROM AUTHOR]

Although adipocytes are major targets of insulin, the influence of impaired insulin action in adipocytes on metabolic homeostasis remains unclear. We here show that adipocyte-specific PDK1 (3′- phosphoinositide-dependent kinase 1)-deficient (A-PDK1KO) mice manifest impaired metabolic actions of insulin in adipose tissue and reduction of adipose tissue mass. A-PDK1KO mice developed insulin resistance, glucose intolerance, and hepatic steatosis, and this phenotype was suppressed by additional ablation of FoxO1 specifically in adipocytes (A-PDK1/FoxO1KO mice) without an effect on adipose tissue mass. Neither circulating levels of adiponectin and leptin nor inflammatory markers in adipose tissue differed between A-PDK1KO and A-PDK1/FoxO1KO mice. Lipidomics and microarray analyses revealed that leukotriene B4 (LTB4) levels in plasma and in adipose tissue as well as the expression of 5- lipoxygenase (5-LO) in adipose tissue were increased and restored in A-PDK1KO mice and A-PDK1/FoxO1KO mice, respectively. Genetic deletion of the LTB4 receptor BLT1 as well as pharmacological intervention to 5-LO or BLT1 ameliorated insulin resistance in A-PDK1KO mice. Furthermore, insulin was found to inhibit LTB4 production through downregulation of 5-LO expression via the PDK1−FoxO1 pathway in isolated adipocytes. Our results indicate that insulin signaling in adipocytes negatively regulates the production of LTB4 via the PDK1−FoxO1 pathway and thereby maintains systemic insulin sensitivity. [ABSTRACT FROM AUTHOR]

Cannabinoids are phytochemicals from cannabis with anti-inflammatory actions in immune cells. Lipid mediators (LM), produced from polyunsaturated fatty acids (PUFA), are potent regulators of the immune response and impact all stages of inflammation. How cannabinoids influence LM biosynthetic networks is unknown. Here, we reveal cannabidiol (CBD) as a potent LM class-switching agent that stimulates the production of specialized pro-resolving mediators (SPMs) but suppresses pro-inflammatory eicosanoid biosynthesis. Detailed metabololipidomics analysis in human monocyte-derived macrophages showed that CBD (i) upregulates exotoxin-stimulated generation of SPMs, (ii) suppresses 5-lipoxygenase (LOX)-mediated leukotriene production, and (iii) strongly induces SPM and 12/15-LOX product formation in resting cells by stimulation of phospholipase A 2 -dependent PUFA release and through Ca2+-independent, allosteric 15-LOX-1 activation. Finally, in zymosan-induced murine peritonitis, CBD increased SPM and 12/15-LOX products and suppressed pro-inflammatory eicosanoid levels in vivo. Switching eicosanoid to SPM production is a plausible mode of action of CBD and a promising inflammation-resolving strategy. [Display omitted] • Anti-inflammatory CBD from cannabis induces a lipid mediator class switch • CBD elicits 15-lipoxygenase product formation in resting human macrophages • CBD seemingly activates 15-lipoxygenase-1 via an allosteric site • In zymosan-induced murine peritonitis, CBD increases SPM production in vivo Peltner et al. reveal cannabidiol from cannabis as lipid mediator class-switching agent that stimulates innate immune cells for producing specialized pro-resolving mediators and suppresses pro-inflammatory leukotriene formation. Cannabidiol activates 15-lipoxygenase-1 via an allosteric site which causes SPM production in human macrophages and in zymosan-induced murine peritonitis in vivo. [ABSTRACT FROM AUTHOR]

During sepsis, the inflammatory response, oxidative stress, and NET release can cause organ damage. Caffeic acid reversed NET release and delayed LPS-stimulated neutrophil apoptosis. Caffeic acid treatment had protective effects on lung and liver injury in a mouse model of sepsis. The mechanism of these protective effects might be related to inhibition of the 5-LOX/LTB4 pathway. [Display omitted] • Caffeic acid protects against lung and liver injury induced by sepsis. • Caffeic acid reduces inflammatory and oxidative responses in the lungs and livers of septic mice. • Caffeic acid inhibits neutrophil inflammatory activation and NET release in vitro. • Caffeic acid reverses delayed apoptosis in the LPS-stimulated human neutrophils. • Caffeic acid modulates activation of neutrophils and attenuates sepsis-induced organ injury by inhibiting 5-LOX/LTB4 pathway. Sepsis is a critical systemic inflammatory syndrome which usually leads to multiple organ dysfunction. Caffeic acid (CA), a phenolic compound derived from various plants, has been proved to be essential in neuroprotection, but its role in septic organ damage is unclear. This research aimed to investigate whether CA protects against organ injury in a mouse model of cecal ligation and puncture (CLP). CA (30 mg/kg) or vehicle was administered by intraperitoneal injection immediately after CLP. The samples of blood, lungs, and livers were collected 24 h later. Organ injury was assessed by histopathological examination (HE staining), neutrophil infiltration (myeloperoxidase fluorescence), oxidative stress levels (MDA, SOD, HO-1), and inflammatory cytokines (TNF-α, IL-1β, and IL-6) release in lung and liver tissues. Neutrophil extracellular trap (NET) formation was analyzed by immunofluorescence. In vitro experiments were performed to investigate the potential mechanisms of CA using small interfering RNA (siRNA) techniques in neutrophils, and the effect of CA on neutrophil apoptosis was analyzed by flow cytometry. Results showed that CA treatment improved the 7-day survival rate and attenuated the histopathological injury in the lung and liver of CLP mice. CA significantly reduced neutrophil infiltration in the lungs and livers of CLP mice. TNF-α, IL-1β, IL-6 and LTB4 were reduced in serum, lung, and liver of CA-treated CLP mice, and phosphorylation of MAPK (p38, ERK, JNK) and p65 NF-κB was inhibited in lungs and livers. CA treatment further increased HO-1 levels and enhanced superoxide dismutase (SOD) activity, but reduced malondialdehyde (MDA) levels and NET formation. Similarly, in vitro experiments showed that CA treatment and 5-LOX siRNA interference inhibited inflammatory activation and NET release in neutrophils, suppressed MAPK and NF-κB phosphorylation in LPS-treated neutrophils, and decreased LTB4 and cfDNA levels. Flow cytometric analysis revealed that CA treatment reversed LPS-mediated delayed apoptosis in human neutrophils, and Western blot also indicated that CA treatment inhibited Bcl-2 expression but increased Bax expression. CA treatment did not induce further changes in neutrophil apoptosis, inflammatory activation, and NET release when 5-LOX was knocked down by siRNA interference. CA has a protective effect on lung and liver injury in a murine model of sepsis, which may be related to inhibition of the 5-LOX/LTB4 pathway. [ABSTRACT FROM AUTHOR]

The intake of food polyphenols is associated with beneficial impacts on health. Besides anti-oxidative effects, anti-inflammatory properties have been suggested as molecular modes of action, which may result from modulations of the arachidonic acid (AA) cascade. Here, we investigated the effects of a library of food polyphenols on 5-lipoxygenase (5-LOX) activity in a cell-free assay, and in human neutrophils. Resveratrol, its dimer (ε-viniferin), and its imine analogue (IRA) potently blocked the 5-LOX-mediated LT formation in neutrophils with IC 50 values in low μM-range. Among the tested flavonoids only the isoflavone genistein showed potent 5-LOX inhibition in neutrophils (IC 50 = 0.4 ± 0.1 μM), however was ineffective on isolated 5-LOX. We exclude an interference with the 5-LOX-activating protein (FLAP) in HEK_5-LOX/±FLAP cells and suggest global effects on intact immune cells. Using LC-MS based targeted oxylipin metabolomics, we analyzed the effects of 5-LOX-inhibiting polyphenols on all branches of the AA cascade in Ca2+-ionophore-challenged neutrophils. While ε-viniferin causes a clear substrate shunt towards the remaining AA cascade enzymes (15-LOX, cyclooxygenase – COX-1/2, cytochrome P450), resveratrol inhibited the COX-1/2 pathway and showed a weak attenuation of 12/15-LOX activity. IRA had no impact on 15-LOX activity, but elevated the formation of COX-derived prostaglandins, having no inhibitory effects on COX-1/2. Overall, we show that food polyphenols have the ability to block 5-LOX activity and the oxylipin pattern is modulated with a remarkable compound/structural specificity. Taken the importance of polyphenols for a healthy diet and their concentration in food supplements into account, this finding justifies further investigation. • Resveratrol and its analogues differently affect oxylipin formation in neutrophils. • Resveratrol, its dimer (ε-Viniferin) and imine analogue (IRA) inhibit 5-LOX. • ε-Viniferin causes a substrate shunt towards the remaining AA cascade enzymes. • Resveratrol inhibits also COX-1/2 and has moderate impact on 12/15-LOX. • IRA does not inhibit 15-LOX and COX-1/2 activity. [ABSTRACT FROM AUTHOR]

5‐lipoxygenase (5‐LO) catalyzes the biosynthesis of leukotrienes, potent lipid mediators involved in inflammatory diseases, and both 5‐LO and the leukotrienes are validated therapeutic targets. Caffeic acid phenethyl ester (CAPE) is an effective inhibitor of 5‐LO and leukotriene biosynthesis but is susceptible to hydrolysis by esterases. In this study a number of CAPE analogues were synthesized with modifications to the caffeoyl moiety and the replacement of the ester linkage with a ketone. Several new molecules showed better inhibition of leukotriene biosynthesis than CAPE in isolated human neutrophils and in whole blood with IC50 values in the nanomolar (290‐520 nmol/L) and low micromolar (1.0‐2.3 µmol/L) ranges, respectively. Sinapic acid and 2,5‐dihydroxy derivatives were more stable than CAPE in whole blood, and ketone analogues were degraded more slowly in HepaRG hepatocyte cultures than esters. All compounds underwent modification consistent with glucuronidation in HepaRG cultures as determined using LC‐MS/MS analysis, though the modified sinapoyl ketone (10) retained 50% of its inhibitory activity after up to one hour of incubation. This study has identified at least one CAPE analogue, compound 10, that shows favorable properties that warrant further in vivo investigation as an antiinflammatory compound. [ABSTRACT FROM AUTHOR]

This study was designed to observe the compensation between cyclooxygenase‐2 pathway and 5‐lipoxygenase pathway in chronic aluminum overload‐induced liver injury rats. A rat hepatic injury model of chronic aluminum injury was established by the intragastric administration of aluminum gluconate (Al3 + 200 mg/kg per day, 5 days a week for 20 weeks). The COX‐2 inhibitor [meloxicam (1 mg/kg)] and 5‐LOX inhibitor [caffeic acid (30 mg/kg)] were intragastrically administered 1 h after aluminum administration. The histopathology was detected by hematoxylin‐eosin staining. A series of biochemical indicators were measured with biochemistry assay or ELISAs. The expressions of COX‐2 and 5‐LOX were measured by immunohistochemistry. Our experimental results showed that aluminum overload caused a significant damage to the liver and also significantly increased the expressions of COX‐2, 5‐LOX and the levels of inflammation and oxidative stress. The administration of meloxicam and caffeic acid significantly protected livers against histopathological injury, significantly decreased plasma ALT, AST, and ALP levels, significantly decreased TNF‐α, IL‐6, IL‐1β levels, and oxidative stress. However, the administration of caffeic acid did not significantly increase the expression of COX‐2 compared with the model group. On the other hand, the administration of meloxicam also did not significantly increase the expression of 5‐LOX compared with the model group. Our results indicate that there is no compensation between COX‐2 pathway and 5‐LOX pathway by inhibiting either COX‐2 or 5‐LOX in chronic aluminum overload‐induced liver injury rat. [ABSTRACT FROM AUTHOR]

Abnormalities of the L-arginine-nitric oxide pathway induce hypertension. 5-Lipoxygenase (5-LO) is the key enzyme involved in synthesis of leukotrienes (LTs). However, whether nitricoxide synthase dysfunction induces hypertensive vascular remodeling by regulating 5-LO activity and its downstream inflammatory metabolites remains unknown. Six-week L-NAME treatment significantly induced hypertension and vascular remodeling in both wild-type (WT) and 5-LO–knockout (5-LO–KO) mice, and blood pressure in caudal and carotid arteries was lower in 5-LO–KO than WT mice with L-NAME exposure. On histology, L-NAME induced less media thickness, media-to-lumen ratio, and collagen deposition and fewer Ki-67–positive vascular smooth muscle cells (VSMCs) but more elastin expression in thoracic and mesenteric aortas of 5-LO–KO than L-NAME–treated WT mice. L-NAME significantly increased LT content, including LTB4 and cysteinyl LT (CysLTs), in plasma and neutrophil culture supernatants from WT mice. On immunohistochemistry, L-NAME promoted the colocalization of 5-LO and 5-LO–activating protein on the nuclear envelope of cultured neutrophils, which was accompanied by elevated LT content in culture supernatants. In addition, LTs significantly promoted BrdU incorporation, migration and phenotypic modulation in VSMCs. L-NAME may activate the 5-LO/LT pathway in immune cells, such as neutrophils, and promote the products of 5-LO metabolites, including LTB4 and CysLTs, which aggravate vascular remodeling in hypertension. 5-LO deficiency may protect against hypertension and vascular remodeling by reducing levels of 5-LO downstream inflammatory metabolites. Unlabelled Image • L-NAME activated 5-LO and boosted 5-LO metabolits, including LTB4 and CysLTs, in neutrophils. • L-NAME induced circulating LTB4 and CysLTs significantly increased in WT mice but not in 5-LO deficient mice. • LTB4 and CysLTs induced remodeling phenotypes, including proliferation, migration, and phenotypic modulation, in VSMCs • 5-LO deficiency protected against L-NAME-induced hypertensive vascular remodeling by reducing 5-LO inflammatory metabolits. [ABSTRACT FROM AUTHOR]

Introduction: Urotensin II (UII) is an important vasoactive peptide involved in the pathogenesis of atherosclerosis. Monocytes/macrophages play important roles in every step of atherosclerosis. Although UII has a chemoattractant effect on monocytes, it is unclear whether UII regulates inflammatory responses in macrophages. The present study sought to explore whether UII can promote leukotriene B4 (LTB4) production by macrophages.Material and Methods: The mRNA expression level of LTB4 and 5-lipoxygenase were determined by real-time polymerase chain reaction. The protein level of LTB4 and 5-lipoxygenase expression was assayed by enzyme-linked immunosorbent assay and Western blot, respectively. Western blot analysis was also employed to determine the phosphorylated forms of Akt. Reactive oxygen species (ROS) level was detected by the fluorescent probe 2',7'-dichlorofluorescin diacetate and fluorescence intensity was measured with a multiwell fluorescence plate reader.Results: Urotensin II promoted LTB4 release and increased 5-lipoxygenase expression in a concentration- and time-dependent manner in RAW264.7 cells. Leukotriene B4 production and 5-lipoxygenase expression were decreased by blocking the UII receptor (UT) with urantide, eliminating ROS with N-acetylcysteine and diphenyliodonium, and inhibiting Akt phosphorylation with LY294002. UII significantly elevated ROS production, whereas urantide, N-acetylcysteine and diphenyliodonium substantially attenuated this effect. UII also enhanced Akt phosphorylation significantly, and this effect was potently inhibited by urantide, N-acetylcysteine, diphenyliodonium and LY294002.Conclusions: Urotensin II may promote 5-lipoxygenase expression and LTB4 release in RAW264.7 macrophages via UT-ROS-Akt pathways. These results indicate that UII may participate in macrophage activation and suggest a potential new mechanism underlying atherosclerosis. [ABSTRACT FROM AUTHOR]

• 5-lipoxygenase is the key enzyme in the biosynthesis of leukotrienes and specialized proresolving lipid mediators (SPM). • 5-lipoxygenase regulates p53 and β-catenin function. • 5-lipoxygenase interacts with dicer. • 5-lipoxygenase regulates stemness. 5-lipoxygenase (5-LO) is the key enzyme in the biosynthesis of leukotrienes and specialized proresolving lipid mediators (SPM). It is mainly expressed in leukocytes and is part of the innate immune system. 5-LO can shuttle between the cytosol and the nucleus. Upon cell activation the protein translocates from soluble cellular compartments to the nuclear membrane. Besides FLAP which is required for cellular leukotriene and SPM formation, 5-LO interacts with other proteins like coactosin-like protein (CLP), Dicer, β-catenin and p53. In this review, the factors involved in the regulation of 5-LO expression, the role of 5-LO in the regulation of stem cell proliferation and differentiation and its biological functions apart from leukotriene and SPM formation are summarized. [ABSTRACT FROM AUTHOR]

Abstract In this paper, 41 hybrid compounds containing diaryl-1,5-diazole and morpholine structures acting as dual COX-2/5-LOX inhibitors have been designed, synthesized and biologically evaluated. Most of them showed potent antiproliferative activities and COX-2/5-LOX inhibitory in vitro. Among them, compound A33 displayed the most potency against cancer cell lines (IC 50 = 6.43–10.97 μ M for F10, HeLa, A549 and MCF-7 cells), lower toxicity to non-cancer cells than celecoxib (A33 : IC 50 = 194.01 μ M vs. celecoxib : IC 50 = 97.87 μ M for 293T cells), and excellent inhibitory activities on COX-2 (IC 50 = 0.17 μ M) and 5-LOX (IC 50 = 0.68 μ M). Meanwhile, the molecular modeling study was performed to position compound A33 into COX-2 and 5-LOX active sites to determine the probable binding models. Mechanistic studies demonstrated that compound A33 could block cell cycle in G2 phase and subsequently induced apoptosis of F10 cells. Furthermore, compound A33 could significantly inhibit tumor growth in F10-xenograft mouse model, and pharmacokinetic study of compound A33 indicated that it showed better stability in vivo. In general, compound A33 could be a promising candidate for cancer therapy. Graphical abstract A series of novel dual COX-2/5-LOX inhibitors have been synthesized and evaluated for their anti-cancer activity as potential COX-2/5-LOX inhibitors. Compound A33 was the most active. Image 1 Highlights • 41 novel diaryl-1,5-diazoles derivatives bearing morpholine have been synthesized. • Their biological activities were evaluated against cancer. • Compound A33 showed the most potent COX-2/5-LOX inhibition. • Compound A33 sufficiently inhibited tumor growth of F10-Xenograft model. [ABSTRACT FROM AUTHOR]

COX-2-selective inhibitors have been associated with an increased risk of cardiovascular complications, and their impact on atherosclerosis (AS) remains controversial. The proinflammatory COX-2 and 5-LO pathways both play essential roles in AS and related cardiovascular diseases. Previous clinical studies have provided evidence of the ability of COX-2-selective inhibitors to shunt AA metabolism from the COX-2 pathway to the 5-LO pathway. In this study, the effects of celecoxib, a selective COX-2 inhibitor, on AS and the COX-2 and 5-LO pathways were investigated in vivo and in vitro. Male ApoE −/− mice fed a western-type diet for 18 weeks and cultured mouse RAW264.7 macrophages stimulated with 1 μg/mL LPS for 24 h were used in this study. In ApoE −/− mice, intragastric administration of celecoxib (80 mg/kg/d) for 18 weeks significantly increased aortic atherosclerotic lesion area but had no effect on hyperlipidemia. In addition, celecoxib significantly lowered TNF-α and PGE 2 levels but increased both LTB 4 and CysLTs levels in aortic tissues. In LPS-stimulated RAW264.7 macrophages, pretreatment with 8 μmol/L celecoxib for 1 h significantly lowered the TNF-α, NO, and PGE 2 levels but increased the LTB 4 and CysLTs levels. Celecoxib also decreased the protein and mRNA expression of COX-2 but increased the expression of 5-LO and LTC 4 S in both ApoE −/− mouse aortic tissues and LPS-stimulated RAW264.7 macrophages. The COX-2-selective inhibitor celecoxib can aggravate atherogenesis, an effect that may be related to upregulation of LTs via a 5-LO pathway shunt. • The COX-2-selective inhibitor celecoxib aggravates atherogenesis but has no effect on hyperlipidemia. • Leukotrienes are upregulated in the celecoxib-treated atherosclerosis (AS) model. • Leukotrienes upregulation is due to the a 5-LO pathway shunt in the celecoxib-treated AS model. [ABSTRACT FROM AUTHOR]

In inflammatory diseases, the 5-lipoxygenase (5-LO) pathway contributes to epithelial damage and fibrosis by catalyzing the production of leukotrienes (LTs). Antagonists of the 5-LO pathway are currently approved for use in patients and are well tolerated. We found that expression of 5-LO is strongly induced in three models of chronic kidney disease: unilateral ureteral obstruction (UUO), folate nephropathy, and an orthologous mouse model of polycystic kidney disease. Immunohistochemistry showed that macrophages are the dominant source of 5-LO. Zileuton, a US Food and Drug Administration-approved antagonist of 5-LO, significantly reduced fibrosis at 7 and 14 days after UUO; these findings were confirmed using a genetically modified [5-LO-associated protein-knockout (Alox5ap−/−)] mouse strain. Inhibition of 5-LO did not appear to change infiltration of leukocytes after UUO as measured by flow cytometry. However, fluorescence-lifetime imaging microscopy showed that 5-LO inhibitors reversed the glycolytic switch in renal tubular epithelial cells after UUO. Two downstream enzymes of 5-LO, LTA4 hydrolase (LTA4H) and LTC4 synthase (LTC4S), are responsible for the synthesis of LTB4 and cysteinyl LTs, respectively. Fibrosis was reduced after UUO in Ltc4s−/−, but not Lta4h−/−, mice. In contrast, using the folate nephropathy model, we found reduced fibrosis and improved renal function in both Ltc4s−/− and Lta4h−/− mice. In summary, our studies suggest that manipulation of the 5-LO pathway may represent a novel treatment approach for chronic kidney disease. [ABSTRACT FROM AUTHOR]