leukotriene-b4 and HIV-Infections

Neutrophil (PMN) dysfunction occurs in HIV infection. Leukotrienes (LT) are mediators derived from the 5-lipoxygenase (5-LO) pathway that play a role in host defense and are synthesized by PMN. We investigated the synthesis of LT by PMN from HIV-infected subjects. There was a reduction (4.0+/-1.3% of control) in LT synthesis in PMN from HIV-infected compared with normal subjects. This was associated with reduced expression of 5-LO-activating protein (31.2+/-9.6% of normal), but not of 5-LO itself. Since HIV does not directly infect PMN, we considered that these effects were due to reduced release of cytokines, such as granulocyte colony-stimulating factor (G-CSF). We examined the effect of G-CSF treatment (300 microgram daily for 5 d) on eight HIV-infected subjects. PMN were studied in vitro before therapy (day 1) and on days 4 and 7. LTB4 synthesis was increased on day 4 of G-CSF treatment, and returned toward day 1 levels on day 7. 5-LO and 5-LO-activating protein expression were increased in parallel. As a functional correlate to this increase in PMN LT synthesis by G-CSF, we examined the effects on killing of Cryptococcus neoformans. Anticryptococcal activity of PMN from HIV-infected subjects was less than that of PMN from normal subjects. G-CSF treatment improved fungistatic activity of PMN. This increase in antifungal activity was attenuated by in vitro treatment with the LT synthesis inhibitor, MK-886. In conclusion, PMN from HIV-infected subjects demonstrate reduced 5-LO metabolism and antifungal activity in vitro, which was reversed by in vivo G-CSF therapy.

Topics: 5-Lipoxygenase-Activating Proteins; AIDS-Related Opportunistic Infections; Arachidonate 5-Lipoxygenase; Arachidonic Acid; Carrier Proteins; Cryptococcus neoformans; Granulocyte Colony-Stimulating Factor; HIV Infections; Humans; Immunity, Cellular; Leukotriene B4; Leukotrienes; Membrane Proteins; Neutrophils; Prospective Studies

Microglia are one of the main cell types to be productively infected by HIV-1 in the central nervous system (CNS). Leukotriene B4 (LTB4) and cysteinyl-leukotrienes such as LTC4 are some of the proinflammatory molecules produced in infected individuals that contribute to neuroinflammation. We therefore sought to investigate the role of leukotrienes (LTs) in HIV-1 infection of microglial cells.. To evaluate the role of LTs on HIV-1 infection in the CNS, monocyte-derived microglial-like cells (MDMis) were utilized in this study. Leukotriene-treated MDMis were infected with either fully replicative brain-derived HIV-1 isolates (YU2) or R5-tropic luciferase-encoding particles in order to assess viral production and expression. The efficacy of various steps of the replication cycle was evaluated by means of p24 quantification by ELISA, luciferase activity determination and quantitative real-time polymerase chain reaction (RT-PCR).. We report in this study that virus replication is reduced upon treatment of MDMis with LTB4 and LTC4. Additional experiments indicate that these proinflammatory molecules alter the pH-independent entry and early post-fusion events of the viral life cycle. Indeed, LT treatment induced a diminution in integrated proviral DNA while reverse-transcribed viral products remained unaffected. Furthermore, decreased C-C chemokine receptor type 5 (CCR5) surface expression was observed in LT-treated MDMis. Finally, the effect of LTs on HIV-1 infection in MDMis appears to be mediated partly via a signal transduction pathway involving protein kinase C.. These data show for the first time that LTs influence microglial cell infection by HIV-1, and may be a factor in the control of viral load in the CNS.

Topics: Brain; Cells, Cultured; Enzyme-Linked Immunosorbent Assay; Flow Cytometry; Gene Expression Regulation, Viral; HIV Infections; HIV-1; Humans; Leukotriene B4; Microglia; Substance P; Transfection

Histoplasma capsulatum (Hc) is a facultative, intracellular parasite of worldwide significance. Infection with Hc produces a broad spectrum of diseases and may progress to a life-threatening systemic disease, particularly in individuals with HIV infection. Resolution of histoplasmosis is associated with the activation of cell-mediated immunity, and leukotriene B(4) plays an important role in this event. Lipid bodies (LBs) are increasingly being recognized as multifunctional organelles with roles in inflammation and infection. In this study, we investigated LB formation in histoplasmosis and its putative function in innate immunity. LB formation in leukocytes harvested from Hc-infected C57BL/6 mice peaks on day 2 postinfection and correlates with enhanced generation of lipid mediators, including leukotriene B(4) and PGE(2). Pretreatment of leukocytes with platelet-activating factor and BLT1 receptor antagonists showed that both lipid mediators are involved in cell signaling for LB formation. Alveolar leukocytes cultured with live or dead Hc also presented an increase in LB numbers. The yeast alkali-insoluble fraction 1, which contains mainly beta-glucan isolated from the Hc cell wall, induced a dose- and time-dependent increase in LB numbers, indicating that beta-glucan plays a signaling role in LB formation. In agreement with this hypothesis, beta-glucan-elicited LB formation was inhibited in leukocytes from 5-LO(-/-), CD18(low) and TLR2(-/-) mice, as well as in leukocytes pretreated with anti-Dectin-1 Ab. Interestingly, human monocytes from HIV-1-infected patients failed to produce LBs after beta-glucan stimulation. These results demonstrate that Hc induces LB formation, an event correlated with eicosanoid production, and suggest a role for these lipid-enriched organelles in host defense during fungal infection.

Topics: Adult; Animals; beta-Glucans; CD18 Antigens; Cell Wall; Enzyme-Linked Immunosorbent Assay; Female; Histoplasma; Histoplasmosis; HIV Infections; HIV-1; Humans; Lectins, C-Type; Leukocytes, Mononuclear; Leukotriene B4; Lipids; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Middle Aged; Nerve Tissue Proteins; Organelles; Toll-Like Receptor 2

CD8(+) T cells can control human immunodeficiency virus (HIV) through the lysis of infected cells and the release of soluble mediators, such as macrophage inflammatory protein (MIP)-1 beta, which prevent entry of HIV and/or inhibit HIV replication. Because neutrophils represent a major source of alpha-defensins and, to a lesser extent, MIP-1 beta, we determined whether leukotriene B(4) (LTB(4)), a potent neutrophil agonist, would trigger the release of these 2 anti-HIV peptides.. Plasma samples from HIV-uninfected subjects receiving intravenous bolus of LTB(4) were analyzed for alpha-defensins and MIP-1 beta levels by use of enzyme-linked immunosorbent assay. Furthermore, in vitro analysis of intracellular and secreted levels of alpha-defensins of resting and LTB(4)-activated neutrophils from HIV-uninfected and HIV-infected subjects were determined. LTB(4) modulation of CD63 and CD66b markers associated with degranulation were studied by use of flow cytometry. Chemotaxis of neutrophils from HIV-uninfected and HIV-infected subjects toward LTB(4) or interleukin (IL)-8 was determined by use of migration assays.. Administration of LTB(4) to humans caused a dose-dependent plasmatic increase in alpha-defensins and MIP-1 beta proteins, with peak levels observed 2 h after administration of LTB(4). Neutrophils isolated from HIV-infected and HIV-uninfected subjects contained similar levels of stored alpha-defensins that were effectively secreted in vitro, in response to LTB(4) activation. Chemotaxis of neutrophils toward LTB(4) or IL-8 was identical among the groups of subjects.. LTB(4) induced the secretion alpha-defensins and MIP-1 beta. Neutrophils from HIV-infected subjects were fully responsive to LTB(4), which highlights a potential usefulness of this lipid mediator in the management of HIV infection.

Topics: alpha-Defensins; Antigens, CD; Antigens, Neoplasm; Cell Adhesion Molecules; Chemokine CCL4; Chemotaxis; Enzyme-Linked Immunosorbent Assay; Flow Cytometry; GPI-Linked Proteins; HIV Infections; HIV-1; Humans; Interleukin-8; Leukotriene B4; Macrophage Inflammatory Proteins; Neutrophils; Platelet Membrane Glycoproteins; Tetraspanin 30

Topics: Animals; Anti-Asthmatic Agents; Asthma; CD4-Positive T-Lymphocytes; Chemotactic Factors; Cloning, Molecular; HIV Infections; HIV-1; Humans; Leukotriene Antagonists; Leukotriene B4; Ligands; Mice; Molecular Sequence Data; Receptors, Formyl Peptide; Receptors, HIV; Receptors, Immunologic; Receptors, Peptide

Human immunodeficiency virus (HIV)-infected patients are at increased risk of contracting bacterial infections, mainly pneumonia. Despite this, little is known about immunopathogenic mechanisms in HIV-related bacterial pneumonia. This paper investigates the presence of the neutrophil chemotactic mediators, interleukin-8 (IL_8) and leukotriene B4 (LTB4), in bronchoalveolar lavage (BAL) fluid from 27 HIV-infected patients with bacterial pneumonia. Significantly elevated levels of IL-8 were found in BAL fluid of patients with bacterial pneumonia [529 pg ml-1 (296-1161 pg ml-1)] compared to matched patients with Pneumocystis carinii pneumonia (PCP) [59 pg ml-1 (42-254 pg ml-1)] and healthy controls [58 pg ml-1 (37-82 pg ml-1)]. Levels of LTB4 were not elevated during bacterial pneumonia when compared to PCP patients and healthy controls. Furthermore, a positive correlation was found between IL-8 levels in BAL fluid and relative BAL neutrophilia (r = 0.60, P = 0.001) in bacterial pneumonia. In conclusion, elevated IL-8 levels in BAL fluid were found in patients suffering from bacterial pneumonia, which may account for the influx of neutrophils to the lung, whereas LTB4 appears not to be an important chemotactic factor in this setting.

Topics: Bronchoalveolar Lavage Fluid; CD4 Lymphocyte Count; Chemotaxis, Leukocyte; Haemophilus Infections; HIV Infections; Humans; Interleukin-8; Leukotriene B4; Neutrophils; Pneumococcal Infections; Pneumonia, Bacterial; Pneumonia, Pneumocystis; Staphylococcal Infections

Pulmonary infection represents a major source of morbidity and mortality in AIDS. One important component of pulmonary host defense is the elaboration by resident alveolar macrophages (AM) of proinflammatory leukotrienes (LT) and other 5-lipoxygenase (5-LO) metabolites of arachidonic acid (AA). In this study, we compared the 5-LO metabolic capacity of AM isolated from normal controls with two groups of HIV-infected subjects: (1) patients with low CD4 counts undergoing diagnostic evaluation for pulmonary indications, and (2) volunteers without pulmonary complaints stratified into normal (> 500) and low (< 200) CD4 count groups. Compared with AM from control subjects, AM from HIV-infected subjects with normal and low CD4 counts demonstrated a marked reduction in LT synthesis. This reduced metabolic capacity could not be attributed to in vivo activation because there was no increase in lavage fluid LTB4 levels. However, there was a reduction (approximately twofold) in 5-LO protein expression in both the normal and the low CD4 subsets. 5-LO-activating protein (FLAP) expression was unchanged in cells from the normal CD4 HIV group, but was decreased threefold in the two groups with low CD4 counts. These observations indicate that there is a graded defect in the 5-LO metabolic capacity of AM from HIV-infected subjects, with decreased expression of only 5-LO in the normal CD4 group, and decreased expression of both 5-LO and FLAP in the low CD4 group. This defect would be expected to compound the immunosuppression seen in these subjects.

Topics: 5-Lipoxygenase-Activating Proteins; Adult; Arachidonate 5-Lipoxygenase; Arachidonic Acid; Bronchoalveolar Lavage Fluid; Carrier Proteins; Culture Media, Conditioned; Enzyme Activation; Female; HIV Infections; Humans; Leukotriene B4; Macrophages, Alveolar; Male; Membrane Proteins; Middle Aged; Tritium

Lipid fractions obtained from Mycobacterium avium serovar 8 were assessed for the ability to affect various immune functions of human peripheral blood mononuclear cells (PBM). Lipids included a total lipid fraction and fractions eluted from silicic acid column separation of that total lipid fraction, using chloroform and chloroform-methanol combinations. Lipid fractions were assayed for total carbohydrate and total 6-deoxyhexose content and were assessed for the ability to influence human macrophage function and the capacity to induce secretion of prostaglandin E2 (PGE2) and tumor necrosis factor alpha in PBM. The total lipid and serovar-specific glycopeptidolipid (GPL) fractions both induced significant levels of tumor necrosis factor alpha, as well as PGE2, in PBM exposed to a sublethal concentration of 100 micrograms lipid per 2 x 10(6) cells. In addition, the same concentrations of the 5 to 7% and GPL fractions induced significant levels of leukotriene B4 in PBM. Comparison of carbohydrate and 6-deoxyhexose contents of each fraction suggested a relationship to carbohydrate content and ability of fractions to induce immune modulator secretion. Analysis of GPL fractions from M. avium serovars 4 and 20 revealed that those GPL lacked the ability to induce PGE2. These results are explained by considering the difference in the carbohydrate residues of the oligosaccharide moieties.

Topics: Adjuvants, Immunologic; Carbohydrate Sequence; Deoxy Sugars; Dinoprostone; Glycolipids; Glycopeptides; HIV Infections; Humans; Leukocytes, Mononuclear; Leukotriene B4; Molecular Sequence Data; Mycobacterium avium Complex; Mycobacterium avium-intracellulare Infection; Serotyping; Tumor Necrosis Factor-alpha

To investigate the pathogenesis of lung injury in Pneumocystic carinii pneumonia and nonspecific interstitial pneumonitis (NIP), common pulmonary complications of human immunodeficiency virus (HIV) infection. The efficacy of corticosteroid therapy in P carinii pneumonia and the observation that bronchoalveolar lavage (BAL) neutrophilia predicts a poor prognosis support the premise that the lung injury of P carinii pneumonia is due to the host's inflammatory response to the infection.. In vitro measurements on previously collected BAL fluid samples.. The Clinical Center of the National Institutes of Health, a research hospital and tertiary care referral center.. Five normal volunteers, 5 asymptomatic HIV-positive patients, 10 HIV-positive patients with NIP (5 asymptomatic and 5 with respiratory symptoms), and 19 HIV-positive patients with P carinii pneumonia.. BAL leukotriene B4 (LTB4), interleukin 8 (IL-8), and phospholipase A2 (PLA2) were measured. IL-8 and PLA2 were elevated in patients with P carinii pneumonia, and IL-8 correlated with BAL fluid absolute neutrophil count. LTB4, IL-8, and PLA2 levels were elevated in patients with NIP; LTB4 and PLA2 levels correlated with absolute neutrophil count, and IL-8 correlated with alveolar-arterial oxygen pressure difference. IL-8 was elevated in the asymptomatic HIV-positive patients, and there was a trend toward elevation of PLA2 in this group.. IL-8 appears to play a role in the pathogenesis of lung injury in P carinii pneumonia and may be the principal neutrophil chemotaxin in this disease; PLA2 may also be involved in the pathogenesis of P carinii pneumonia. Both LTB4 and IL-8 may be involved in the recruitment of neutrophils and subsequent lung injury of NIP. These data suggest that there are varying mechanisms by which inflammatory cells are recruited to the lung in different HIV-related lung diseases.

Topics: Adult; AIDS-Related Opportunistic Infections; Bronchoalveolar Lavage Fluid; Chromatography, High Pressure Liquid; Female; HIV Infections; HIV Seropositivity; Humans; Interleukin-8; Leukotriene B4; Lung Diseases; Male; Middle Aged; Phospholipases A; Phospholipases A2; Pneumonia, Pneumocystis; Pulmonary Fibrosis