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Prostaglandins & Other Lipid Mediators Oct 2021Human B-lymphocytes express 5-lipoxygenase (5-LOX) and 5-LOX activating protein (FLAP) and can convert arachidonic acid to leukotriene B. Mantle cell lymphoma (MCL)...
Human B-lymphocytes express 5-lipoxygenase (5-LOX) and 5-LOX activating protein (FLAP) and can convert arachidonic acid to leukotriene B. Mantle cell lymphoma (MCL) cells contain similar amounts of 5-LOX as human neutrophils but the function and mechanism of activation of 5-LOX in MCL cells, and in normal B-lymphocytes, are unclear. Here we show that the intrinsic 5-LOX pathway in the MCL cell line JeKo-1 has an essential role in migration and adherence of the cells, which are important pathophysiological characteristics of B-cell lymphoma. Incubation of JeKo-1 with the FLAP inhibitor GSK2190915 or the 5-LOX inhibitor zileuton, at a concentration below 1 μM, prior to stimulation with the chemotactic agent CXCL12, led to a significant reduction of migration. CRISPR/Cas9 mediated deletion of ALOX5 gene in JeKo-1 cells also led to a significantly decreased migration of the cells. Furthermore, 5-LOX and FLAP inhibitors markedly decreased the adherence of JeKo-1 cells to stromal cells. In comparison, these drugs had a similar effect on adherence of JeKo-1 cells as the Bruton tyrosine kinase inhibitor ibrutinib, which has a proven anti-tumour effect. These results indicate that inhibition of 5-LOX may be a novel treatment for MCL and certain other B-cell lymphomas.
Topics: Lymphoma, Mantle-Cell
PubMed: 34116165
DOI: 10.1016/j.prostaglandins.2021.106575 -
Scientific Reports May 2021Monocyte chemoattractant protein-1 (MCP-1) plays an important role in initiating vascular inflammation; however, its cellular source in the injured vasculatures is...
Monocyte chemoattractant protein-1 (MCP-1) plays an important role in initiating vascular inflammation; however, its cellular source in the injured vasculatures is unclear. Given the importance of high mobility group box 1 (HMGB1) in tissue injury, we investigated the role of vascular smooth muscle cells (VSMCs) in MCP-1 production in response to HMGB1. In primary cultured rat aortic VSMCs stimulated with HMGB1, the expression of MCP-1 and 5-lipoxygenase (LO) was increased. The increased MCP-1 expression in HMGB1 (30 ng/ml)-stimulated cells was significantly attenuated in 5-LO-deficient cells as well as in cells treated with zileuton, a 5-LO inhibitor. Likewise, MCP-1 expression and production were also increased in cells stimulated with exogenous leukotriene B4 (LTB4), but not exogenous LTC4. LTB4-induced MCP-1 expression was attenuated in cells treated with U75302, a LTB4 receptor 1 (BLTR1) inhibitor as well as in BLTR1-deficient cells, but not in 5-LO-deficient cells. Moreover, HMGB1-induced MCP-1 expression was attenuated in BLTR1-deficient cells or by treatment with a BLTR1 inhibitor, but not other leukotriene receptor inhibitors. In contrast to MCP-1 expression in response to LTB4, the increased MCP-1 production in HMGB1-stimulated VSMC was markedly attenuated in 5-LO-deficient cells, indicating a pivotal role of LTB4-BLTR1 signaling in MCP-1 expression in VSMCs. Taken together, 5-LO-derived LTB4 plays a key role in MCP-1 expression in HMGB1-exposed VSMCs via BLTR1 signaling, suggesting the LTB4-BLTR1 signaling axis as a potential therapeutic target for vascular inflammation in the injured vasculatures.
Topics: Animals; Aorta; Arachidonate 5-Lipoxygenase; Chemokine CCL2; Fatty Alcohols; Glycols; HMGB1 Protein; Hydroxyurea; Leukotriene B4; Mice, Knockout; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Rats; Rats, Sprague-Dawley; Signal Transduction; Mice
PubMed: 34045591
DOI: 10.1038/s41598-021-90636-2 -
Aging Apr 2021Early brain injury (EBI) is a major contributor to the high mortality and morbidity after subarachnoid hemorrhage (SAH). Inflammatory responses and neuronal apoptosis...
Early brain injury (EBI) is a major contributor to the high mortality and morbidity after subarachnoid hemorrhage (SAH). Inflammatory responses and neuronal apoptosis are important causes of EBI. Because 5- lipoxygenase (5-LOX) is known to be involved various central nervous system diseases, we investigated the effects of 5-LOX inhibition during EBI after SAH. Zileuton and LY294002 were used to inhibit expression of 5-LOX and Akt, respectively. We found that 5-LOX expression was significantly increased in the cytoplasm of cortical neurons after SAH and was accompanied by upregulated expression of the inflammatory factors LTB4, TNF-α, IL-1β and IL-6; upregulation of the pro-apoptotic factor Bax; downregulation of the anti-apoptotic factor Bcl-2; and an increased apoptosis rate. Gastric Zileuton administration significantly suppressed all of those effects and improved neurological function. Zileuton also upregulated activated (phosphorylated) AKT levels, and these beneficial effects of Zileuton were abolished by intracerebroventricular infusion of the PI3K inhibitor LY294002. Taken together, these findings indicate that 5-LOX mediates pro-inflammatory and pro-apoptotic effects that contribute to EBI after SAH and that those effects are suppressed by activation of PI3K/Akt signaling. This suggests targeting 5-LOX may be an effective approach to treating EBI after SAH.
Topics: Administration, Oral; Animals; Apoptosis; Arachidonate 5-Lipoxygenase; Brain Injuries; Chromones; Disease Models, Animal; Humans; Hydroxyurea; Inflammation; Infusions, Intraventricular; Lipoxygenase Inhibitors; Male; Morpholines; Neurons; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Rats; Signal Transduction; Subarachnoid Hemorrhage
PubMed: 33878031
DOI: 10.18632/aging.202869 -
Oncology Letters May 2021Janus kinase 2 (JAK2) inhibitors, the first targeted treatments for myeloproliferative neoplasms (MPNs), provide substantial benefits, including a marked reduction in...
Janus kinase 2 (JAK2) inhibitors, the first targeted treatments for myeloproliferative neoplasms (MPNs), provide substantial benefits, including a marked reduction in splenomegaly and MPN-associated symptoms. However, these drugs rarely induce molecular remission in patients with MPNs. Zileuton, a 5-lipoxygenase (5-LO) inhibitor, has been demonstrated to selectively deplete hematopoietic stem cells (HSCs) expressing a JAK2 point mutation (JAK2V617F) in mouse models of JAK2V617F-induced polycythemia vera (PV). To determine the potential activity of 5-LO inhibitors in combination with JAK inhibitors against human PV HSCs, the present study first analyzed 5-LO expression in CD34 bone marrow cells from patients with JAK2V617F-positive PV using western blotting and reverse transcription-quantitative PCR, and then examined the effect of zileuton combined with ruxolitinib on colony formation using a colony formation assay. Furthermore, cell cycle and apoptosis in CD34 cells from patients with PV and healthy volunteers were determined by flow cytometry. In the present study, 5-LO expression was upregulated in CD34 cells from patients with PV compared with in CD34 cells from healthy volunteers. Higher levels of leukotriene B4, a product of the 5-LO signaling pathway, were detected in patients with PV compared with in healthy volunteers. Zileuton treatment suppressed the colony formation of CD34 cells from patients with PV in a dose-dependent manner. Furthermore, zileuton and ruxolitinib exerted their anticancer effects by suppressing hematopoietic colony formation, inducing apoptosis and arresting the cell cycle of human CD34 cells from patients with PV. The combination of these two drugs exerted a more beneficial effect than either agent alone. Based on these data, zileuton enhanced the antitumor activity of low-dose ruxolitinib in hematopoietic progenitor cells from patients with PV, providing conceptual validation for further clinical applications of combination treatment with ruxolitinib and zileuton for patients with PV.
PubMed: 33747208
DOI: 10.3892/ol.2021.12612 -
Blocking 5-LO pathway alleviates renal fibrosis by inhibiting the epithelial-mesenchymal transition.Biomedicine & Pharmacotherapy =... Jun 2021The enzyme 5-lipoxygenase (5-LO) converts arachidonic acid to leukotrienes, which mediate inflammation. The enzyme is known to contribute to organ fibrosis, but how it...
The enzyme 5-lipoxygenase (5-LO) converts arachidonic acid to leukotrienes, which mediate inflammation. The enzyme is known to contribute to organ fibrosis, but how it contributes to renal fibrosis is unclear. Here, we reported that fibrotic kidneys expressed high levels of 5-LO, and deleting the 5-LO gene mitigated renal fibrosis in mice subjected to unilateral ureteral obstruction (UUO), based on assays of collagen deposition, injury and inflammation. Mechanistically, the exogenous leukotrienes B and C, the downstream products of 5-LO, could induce the epithelial-mesenchymal transition (EMT) in kidney epithelial cell cultures, based on assays of E-cadherin, vimentin and snail expression. Studies in UUO mice confirmed that 5-LO deletion inhibited the EMT in the obstructed kidney. More importantly, 5-LO inhibitor zileuton loaded in CREKA-Lip, which could target to fibrotic kidney, markedly attenuated UUO-induced renal fibrosis and injury by inhibiting the EMT in the obstructed kidney. Our results suggested that 5-LO activity may contribute to renal fibrosis by promoting renal EMT, implying that the enzyme may be a useful therapeutic target.
Topics: 5-Lipoxygenase-Activating Protein Inhibitors; 5-Lipoxygenase-Activating Proteins; Animals; Cells, Cultured; Epithelial-Mesenchymal Transition; Female; Fibrosis; Humans; Kidney Diseases; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Signal Transduction
PubMed: 33721755
DOI: 10.1016/j.biopha.2021.111470 -
Frontiers in Pharmacology 2021Activation of hepatic stellate cells (HSC) is a central driver of liver fibrosis. 5-lipoxygenase (5-LO) is the key enzyme that catalyzes arachidonic acid into...
Activation of hepatic stellate cells (HSC) is a central driver of liver fibrosis. 5-lipoxygenase (5-LO) is the key enzyme that catalyzes arachidonic acid into leukotrienes. In this study, we examined the role of 5-LO in HSC activation and liver fibrosis. Culture medium was collected from quiescent and activated HSC for target metabolomics analysis. Exogenous leukotrienes were added to culture medium to explore their effect in activating HSC. Genetic ablation of 5-LO in mice was used to study its role in liver fibrosis induced by CCl and a methionine-choline-deficient (MCD) diet. Pharmacological inhibition of 5-LO in HSC was used to explore the effect of this enzyme in HSC activation and liver fibrosis. The secretion of LTB and LTC was increased in activated vs. quiescent HSC. LTB and LTC contributed to HSC activation by activating the extracellular signal-regulated protein kinase pathway. The expression of 5-LO was increased in activated HSC and fibrotic livers of mice. Ablation of 5-LO in primary HSC inhibited both mRNA and protein expression of fibrotic genes. , ablation of 5-LO markedly ameliorated the CCl- and MCD diet-induced liver fibrosis and liver injury. Pharmacological inhibition of 5-LO in HSC by targeted delivery of the 5-LO inhibitor zileuton suppressed HSC activation and improved CCl- and MCD diet-induced hepatic fibrosis and liver injury. Finally, we found increased 5-LO expression in patients with non-alcoholic steatohepatitis and liver fibrosis. 5-LO may play a critical role in activating HSC; genetic ablation or pharmacological inhibition of 5-LO improved CCl-and MCD diet-induced liver fibrosis.
PubMed: 33679410
DOI: 10.3389/fphar.2021.628583 -
Iranian Journal of Basic Medical... Dec 2020Regarding gastroprotective effects, we investigated the protective effects of extracts on reducing gastric ulcer induced by indomethacin.
OBJECTIVES
Regarding gastroprotective effects, we investigated the protective effects of extracts on reducing gastric ulcer induced by indomethacin.
MATERIALS AND METHODS
Rats received aqueous and ethanolic extracts of (50, 100, and 200 mg/kg), zileuton (100 mg/kg), montelukast (10 mg/kg), or 1% Tween 80 in presence or absence of indomethacin (100 mg/kg).
RESULTS
Indomethacin produced stomach ulcer and increased neutrophils percentage and MDA level compared with the control group (0.001). Co-administration of indomethacin and zileuton, montelukast and ethanolic (200 mg/kg) (0.001), aqueous extract (200 mg/kg) (0.05) reduced ulcer compared with the indomethacin group (0.001). Ethanolic extracts (100 and 200 mg/kg) and aqueous extract (200 mg/kg) reduced the MDA level (0.001). Ethanolic (50, 100, and 200 mg/kg) and aqueous extracts (200 mg/kg) significantly decreased neutrophils percentage compared with the indomethacin group (0.001).
CONCLUSION
Aqueous and particularly ethanolic extracts of have protective effects on indomethacin-induced gastric ulcers.
PubMed: 33489039
DOI: 10.22038/ijbms.2020.44341.10377 -
Molecules (Basel, Switzerland) Oct 2020A novel series of zileuton-hydroxycinnamic acid hybrids were synthesized and screened as 5-lipoxygenase (5-LO) inhibitors in stimulated HEK293 cells and...
A novel series of zileuton-hydroxycinnamic acid hybrids were synthesized and screened as 5-lipoxygenase (5-LO) inhibitors in stimulated HEK293 cells and polymorphonuclear leukocytes (PMNL). Zileuton's () benzo[b]thiophene and hydroxyurea subunits combined with hydroxycinnamic acid esters' ester linkage and phenolic acid moieties were investigated. Compound , bearing zileuton's () benzo[b]thiophene and sinapic acid phenethyl ester's () α,β-unsaturated phenolic acid moiety was shown to be equipotent to zileuton (), the only clinically approved 5-LO inhibitor, in stimulated HEK293 cells. Compound was three times as active as zileuton () for the inhibition of 5-LO in PMNL. Compound , bearing the same sinapic acid (3,5-dimethoxy-4-hydroxy substitution) moiety as , combined with zileuton's () hydroxyurea subunit was inactive. This result shows that the zileuton's () benzo[b]thiophene moiety is essential for the inhibition of 5-LO product biosynthesis with our hydrids. Unlike zileuton (), Compound formed two π-π interactions with Phe177 and Phe421 as predicted when docked into 5-LO. Compound was the only docked ligand that showed a π-π interaction with Phe177 which may play a part in product specificity as reported.
Topics: Arachidonate 5-Lipoxygenase; Computer Simulation; Coumaric Acids; Drug Evaluation, Preclinical; Free Radical Scavengers; HEK293 Cells; Humans; Hydroxyurea; Lipoxygenase Inhibitors; Molecular Docking Simulation; Neutrophils; Structure-Activity Relationship
PubMed: 33066378
DOI: 10.3390/molecules25204686 -
Prostaglandins, Leukotrienes, and... Oct 2020
Topics: Acetates; Adrenal Cortex Hormones; Anti-Inflammatory Agents, Non-Steroidal; Arachidonic Acid; Betacoronavirus; COVID-19; Coronavirus Infections; Cyclopropanes; Cytokine Release Syndrome; Humans; Hydroxyurea; Immunologic Factors; Indoles; Leukotrienes; Pandemics; Phenylcarbamates; Pneumonia, Viral; Quinolines; SARS-CoV-2; Severity of Illness Index; Sulfides; Sulfonamides; Tosyl Compounds
PubMed: 32977289
DOI: 10.1016/j.plefa.2020.102174 -
Biomedicines Sep 2020Dry eye syndrome (DES) is characterized by decreased tear production and stability, leading to desiccating stress, inflammation and corneal damage. DES treatment may...
Dry eye syndrome (DES) is characterized by decreased tear production and stability, leading to desiccating stress, inflammation and corneal damage. DES treatment may involve targeting the contributing inflammatory pathways mediated by polyunsaturated fatty acids and their derivatives, oxylipins. Here, using an animal model of general anesthesia-induced DES, we addressed these pathways by characterizing inflammatory changes in tear lipidome, in correlation with pathophysiological and biochemical signs of the disease. The decline in tear production was associated with the infiltration of inflammatory cells in the corneal stroma, which manifested one to three days after anesthesia, accompanied by changes in tear antioxidants and cytokines, resulting in persistent damage to the corneal epithelium. The inflammatory response manifested in the tear fluid as a short-term increase in linoleic and alpha-linolenic acid-derived oxylipins, followed by elevation in arachidonic acid and its derivatives, leukotriene B4 (5-lipoxigenase product), 12-hydroxyeicosatetraenoic acid (12-lipoxigeanse product) and prostaglandins, D2, E2 and F2α (cyclooxygenase products) that was observed for up to 7 days. Given these data, DES was treated by a novel ophthalmic formulation containing a dimethyl sulfoxide-based solution of zileuton, an inhibitor of 5-lipoxigenase and arachidonic acid release. The therapy markedly improved the corneal state in DES by attenuating cytokine- and oxylipin-mediated inflammatory responses, without affecting tear production rates. Interestingly, the high efficacy of the proposed therapy resulted from the synergetic action of its components, namely, the general healing activity of dimethyl sulfoxide, suppressing prostaglandins and the more specific effect of zileuton, downregulating leukotriene B4 (inhibition of T-cell recruitment), as well as upregulating docosahexaenoic acid (activation of resolution pathways).
PubMed: 32932827
DOI: 10.3390/biomedicines8090344