interleukin-8 and zileuton

Arachidonic acid (AA) activates the 5-lipoxygenase, induces leukotriene-B(4) (LTB(4)) synthesis, enhances interleukin-6 (IL-6) release and increases intracellular neutral lipids in human sebocytes. Moreover, the enzymes of LTB(4) biosynthesis are activated in acne-involved sebaceous glands. Zileuton a 5-lipoxygenase inhibitor, reduces the number of inflammatory acne lesions and lipogenesis in patients with acne. In this study, we investigated the activity of zileuton on LTB(4) generation, lipid content and IL-6 and -8 release from human SZ95 sebocytes in vitro. Pretreatment with zileuton partially prevented the AA-induced LTB(4) and IL-6 release and increased neutral lipid content. IL-6 release and neutral lipid content were also reduced under long-term zileuton treatment. In conclusion, zileuton prevents the activation of the leukotriene pathway and enhancement of lipogenesis by AA in human sebocytes in vitro.

Topics: Arachidonic Acid; Cell Count; Cell Line; Humans; Hydroxyurea; Interleukin-6; Interleukin-8; Leukotriene Antagonists; Leukotriene B4; Lipogenesis; Sebaceous Glands

In 16HBE transformed human bronchial epithelial cells, histamine stimulated interleukin (IL)-8 mRNA and protein secretion, and this histamine stimulation was inhibited by the H1-receptor antagonist diphenhydramine (DPH), by the inhibitor of 5-lipoxygenase-activating protein (FLAP) MK-886, by the 5-lipoxygenase inhibitor Zileuton, and by dexamethasone. Histamine stimulated bronchial epithelial cell production of leukotriene B4 (LTB4), and this production was inhibited by FLAP inhibitors MK-886 and L-655,238 and Zileuton. Histamine stimulated IL-8 luciferase reporter gene activity that was inhibited with DPH, dexamethasone, MK-886 and L-655,238, and Zileuton. The inhibition of IL-8 transcription and protein secretion by FLAP inhibitors and Zileuton was reversed with exogenous LTB4. There was increased IL-8 nuclear factor-kappaB (NF-kappaB) DNA-binding activity after histamine stimulation, and this was inhibited by DPH and MK-886. Cytoplasmic phospholipase A2 mRNA levels were also potently induced by histamine. Thus histamine stimulation of bronchial epithelial cells involves binding at H1 receptors, production of LTB4, activation of NF-kappaB and increased expression of IL-8.

Topics: Bronchi; Cell Line; Cell Line, Transformed; Epithelial Cells; Histamine; Humans; Hydroxyurea; Indoles; Interleukin-8; Leukotriene B4; Lipoxygenase Inhibitors; NF-kappa B; Phospholipases A; Phospholipases A2; Polymerase Chain Reaction; Quinolines; RNA, Messenger; Transfection

Leukotriene B4 (LTB4), a potent chemokinetic mediator for neutrophils, is enhanced by interleukin-8 (IL-8) and may play a key role in the inflammatory response of asthma.. The aim of the present study was to investigate whether zileuton, a 5-lipoxygenase antagonist known to inhibit LTB4 production and recruitment of eosinophils/neutrophils in bronchoalveolar fluid, could affect the production of LTB4 and IL-8 by allergen-stimulated peripheral blood mononuclear cells in vitro from patients with asthma and/or allergic rhinitis.. Peripheral blood mononuclear cells were isolated using Ficoll-Hypaque density gradient from 14 subjects (2 with asthma, 11 with asthma and allergic rhinitis, and 1 with allergic rhinitis) and were stimulated by selected allergens (grass, tree, mite, and mold) in the absence or presence of 1 and 10 microM of zileuton. Supernatants were collected and assayed for LTB4 and IL-8 levels using RIA and ELISA, respectively.. Levels of LTB4 were significantly elevated in peripheral blood mononuclear cells stimulated with mold, grass, and tree compared with the unstimulated control group (P<.05). Levels of IL-8 were significantly elevated in all allergen-stimulated peripheral blood mononuclear cells, except mold, compared with the unstimulated control group (P<.05). Zileuton significantly reduced production of LTB4 by mold and tree-stimulated peripheral blood mononuclear cells. By contrast, no effect of zileuton on IL-8 production was observed in allergen-stimulated peripheral blood mononuclear cells.. The zileuton-induced attenuation of LTB4 production by allergen-stimulated peripheral blood mononuclear cells from patients with asthma and/or allergic rhinitis occurs independently from the allergen-stimulated IL-8 production.

Topics: Adult; Aged; Allergens; Asthma; Female; Humans; Hydroxyurea; Interleukin-8; Leukocytes, Mononuclear; Leukotriene B4; Lipoxygenase Inhibitors; Male; Middle Aged; Rhinitis, Allergic, Perennial; Rhinitis, Allergic, Seasonal

Pyocyanin (Pyo) and 1-hydroxyphenazine (1-HP) are extracellular products of Pseudomonas aeruginosa. To test whether these products were capable of producing an inflammatory response in the airways, combinations of Pyo and 1-HP at concentrations of 10(-4) and 10(-5) M were instilled into sheep airways, and indexes of inflammation were assessed by bronchoalveolar lavage (BAL) 24 h later. Challenge with the phenazines caused a significant dose-dependent increase in the number of cells and neutrophils recovered by BAL. Control challenges produced no such changes. The lung neutrophilia was accompanied by an increased concentration of albumin in BAL. The increases in BAL neutrophils and albumin could be blocked by treating the sheep with the 5-lipoxygenase inhibitor zileuton. Neither 1-HP nor Pyo was chemotactic to neutrophils when tested in vitro, but when alveolar macrophages (AM) were cultured in vitro in the presence of both Pyo and 1-HP (1 microM), the supernatants caused neutrophil chemotaxis. Analysis of AM culture supernatants incubated with the combination of pigments showed significant increases in leukotriene B4 and interleukin-8, and blocking these mediators separately or together reduced AM supernatant-induced neutrophil chemotaxis. We conclude that local instillation of Pyo and 1-HP can initiate an inflammatory response in the airways of sheep in vivo. This effect can be explained, in part, by the release of chemotactic factors produced by AM.

Topics: Animals; Bronchoalveolar Lavage Fluid; Chemotaxis, Leukocyte; Female; Hydroxyurea; In Vitro Techniques; Interleukin-8; Leukotriene B4; Lung; Macrophages, Alveolar; Neutrophils; Phenazines; Pseudomonas aeruginosa; Pyocyanine; Sheep

We found that intrinsic neutrophil 5-lipoxygenase activity was necessary for human neutrophil adherence and chemotaxis in vitro and human neutrophil-mediated acute edematous injury in isolated perfused rat lungs given interleukin 8 intratracheally. Treatment with either Zileuton (a specific reversible competitive inhibitor of 5-lipoxygenase) or MK886 (a specific irreversible inhibitor of the 5-lipoxygenase activator protein) prevented stimulated neutrophil adherence and chemotaxis (but not superoxide anion production) in vitro. Zileuton- or MK886-inhibited neutrophil chemotaxis was not restored by adding leukotriene B4 in vitro. Perfusion with neutrophils and either Zileuton or MK886, or with MK886-pretreated neutrophils (without adding MK886 to the perfusate), also prevented lung injury (reflected by lung weight gain and lung Ficoll retention) and perfusate leukotriene B4 increases in isolated rat lungs given interleukin 8 intratracheally. Again, adding leukotriene B4 to the perfusate did not damage interleukin 8-treated isolated lungs perfused with Zileuton-inhibited neutrophils. We conclude that intrinsic 5-lipoxygenase activity is required for neutrophil adherence and chemotaxis and neutrophil-mediated lung injury.

Topics: Animals; Arachidonate 5-Lipoxygenase; Cell Adhesion; Chemotaxis, Leukocyte; Cytochrome c Group; Dose-Response Relationship, Drug; Humans; Hydroxyurea; In Vitro Techniques; Indoles; Interleukin-8; Kinetics; Leukotriene Antagonists; Leukotriene B4; Lipoxygenase Inhibitors; Lung; Male; Neutrophils; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Superoxides; Tetradecanoylphorbol Acetate