Prolonged cigarette smoke exposure decreases heme oxygenase-1 and alters Nrf2 and Bach1 expression in human macrophages: roles of the MAP kinases ERK(1/2) and JNK.

Tobacco may be involved in the decreased macrophage heme oxygenase-1 (HO-1) expression described in smoking-induced severe emphysema, via the nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein 1 (Keap1)-BTB and CNC homology 1, basic leucine zipper transcription factor 1 (Bach1) pathway. We assessed in vitro effects of cigarette smoke condensate (CS) in the human monocyte/macrophage cell line (THP-1). CS exposure led to increased HO-1 and nuclear Nrf2 expression (6 h) followed by decreased HO-1 expression concomitantly with nuclear Nrf2/Bach1 ratio decrease (72h). CS-induced mitogen-activated protein kinase (MAPK) phosphorylation. Extracellular-signal-regulated kinase(1/2) (ERK(1/2)) and c-Jun NH2-terminal kinase (JNK) inhibition completely abrogated CS effects on HO-1 expression and nuclear Nrf2/Bach1 translocation. These results suggest that ERK(1/2) and JNK are involved in CS-induced biphasic HO-1 expression by a specific regulation of Nrf2/Keap1-Bach1.

Altered Nrf2/Keap1-Bach1 equilibrium in pulmonary emphysema.

BACKGROUND: Oxidative stress, resulting from the increased oxidative burden and decreased level of antioxidant proteins, plays a role in the pathophysiology of smoking-related pulmonary emphysema. Expression of several antioxidant proteins, such as heme oxygenase-1 (HO-1), glutathione peroxidase 2 (GPX2) and NAD(P)H:quinone oxidoreductase 1 (NQO1), results from an equilibrium created by positive or negative regulation by the transcription factors Nrf2, Keap1 and Bach1, respectively. However, whether the expression of these transcription factors is altered in emphysema and could account for decreased expression of antioxidant proteins is not known. A study was undertaken to investigate the expression and subcellular localisation of Nrf2, Keap1 and Bach1 as potential regulators of HO-1, GPX2 and NQO1 in alveolar macrophages, a key cell in oxidative stress, in lung surgical specimens from non-smokers without emphysema and smokers with and without emphysema. METHODS AND RESULTS: Western blot, immunohistochemical and laser scanning confocal analysis revealed that the Nrf2 protein level decreased significantly in whole lung tissue and alveolar macrophages (cytosol and nucleus) in patients with emphysema compared with those without emphysema. Conversely, Bach1 and Keap1 levels were increased in patients with emphysema. These modifications were associated with a parallel decrease in the expression of HO-1, GPX2 and NQO1 at the cellular level, which was inversely correlated with airway obstruction and distension indexes, and increased macrophage expression of the lipid peroxidation product 4-hydroxy-2-nonenal. Silencing RNA experiments in vitro in THP-1 cells were performed to confirm the cause-effect relation between the loss of Nrf2 and the decrease in HO-1, NQO1 and GPX2 expression. Nrf2/Keap1-Bach1 equilibrium was altered in alveolar macrophages in pulmonary emphysema, which points to a decreased stress response phenotype. CONCLUSIONS: This finding opens a new view of the pathophysiology of emphysema and could provide the basis for new therapeutic approaches based on preservation and/or restoration of such equilibrium.

Changes in airway inflammation following nasal allergic challenge in patients with seasonal rhinitis.

BACKGROUND: Seasonal allergic rhinitis could predispose to the development of chronic bronchial inflammation as observed in asthma. However, direct links between nasal inflammation, bronchial inflammation and airway responsiveness in patients with seasonal allergic rhinitis and without asthma are not fully understood. The aim of this study was to analyse the changes induced by allergic nasal challenge outside the pollen season in airway responsiveness and bronchial inflammation of patients with seasonal allergic rhinitis. METHODS: Nine patients were evaluated after either grass pollens or placebo nasal challenge in a randomized cross-over double-blinded trial. Nasal parameters were recorded hourly and airway responsiveness was assessed by methacholine challenge. Cytological examinations and cytokine measurements were performed in nasal lavage and induced sputum. Eosinophil activation was investigated by eosinophil-cationic protein expression and secretion. RESULTS: Airway responsiveness was increased after allergic nasal challenge. Total eosinophils and eosinophils expressing eosinophil-cationic protein were increased in induced sputum after allergic nasal challenge. Both eosinophil number and eosinophil-cationic protein concentration in induced sputum were correlated to methacholine responsiveness. CONCLUSIONS: These results suggest that eosinophils participate to the bronchial inflammation in patients with seasonal allergic rhinitis following allergic nasal challenge outside the pollen season and might explain changes in airway responsiveness.

Decreased expression of interleukin 13 in human lung emphysema.

BACKGROUND: The overexpression of interferon (IFN)gamma or interleukin (IL)-13 in the adult murine lung induces the development of changes that mirror human lung emphysema. METHODS: IL-13 and IFNgamma expression was determined in lung samples from five groups of PATIENTS: severe emphysema without alpha(1)-antitrypsin deficiency (SE+, n = 10); severe emphysema with alpha(1)-antitrypsin deficiency (SE-, n = 5); mild localised emphysema (ME, n = 8); non-emphysema smokers (NE-S, n = 9), and non-emphysema non-smokers (NE-NS, n = 11). Lung IL-13 and IFNgamma mRNA were analysed by RT-PCR. Lung concentrations of IL-13 protein were assessed by ELISA. RESULTS: The expression of IFNgamma mRNA was similar in patients with or without emphysema. IL-13 mRNA was markedly decreased in the SE+ group compared with the SE- (p = 0.04), ME (p = 0.02), and non-emphysema groups (p = 0.01). IL-13 mRNA correlated with forced expiratory volume in 1 second (r = 0.5, p = 0.04) and arterial oxygen tension (r = 0.45, p = 0.03) in emphysema patients. In contrast to the non-emphysematous lung, IL-13 protein was below the detection limit of the assay in most emphysematous lung homogenates. CONCLUSION: The lung IL-13 content is reduced in patients with severe emphysema without alpha(1)-antitrypsin deficiency.

Halothane reduces the early lipopolysaccharide-induced lung inflammation in mechanically ventilated rats.

Several studies suggest that anesthetics modulate the immune response. The aim of this study was to investigate the effect of halothane and thiopental on the lung inflammatory response. Rats submitted or not to intratracheal (IT) instillation of lipopolysaccharides (LPS) were anesthetized with either halothane (0. 5, 1, or 1.5%) or thiopental (60 mg. kg(-1)) and mechanically ventilated for 4 h. Control rats were treated or not by LPS without anesthesia. Lung inflammation was assessed by total and differential cell counts in bronchoalveolar lavage fluids (BALF) and by cytokine measurements (tumor necrosis factor-alpha [TNF-alpha], interleukin-6 [IL-6], macrophage inflammatory protein-2 [MIP-2], and monocyte chemoattractant protein-1 [MCP-1]) in BALF and lung homogenates. In the absence of LPS treatment, neither halothane nor thiopental modified the moderate inflammatory response induced by tracheotomy or mechanical ventilation. Cell recruitment and cytokine concentrations were increased in all groups receiving IT LPS. However, in halothane-anesthetized rats (halothane > or = 1%), but not in thiopental-anesthetized rats, the LPS-induced lung inflammation was altered in a dose-dependent manner. Indeed, when using 1% halothane, polymorphonuclear leukocyte (PMN) recruitment was decreased by 55% (p < 0.001) and TNF-alpha, IL-6, and MIP-2 concentrations in BALF and lung homogenates were decreased by more than 60% (p < 0.001) whereas total protein and MCP-1 concentrations remained unchanged. The decrease of MIP-2 (observed at the protein and messenger RNA [mRNA] level) was strongly correlated to the decrease of PMN recruitment (r = 0.73, p < 0.05). This halothane-reduced lung inflammatory response was transient and was reversed 20 h after the end of the anesthesia. Our study shows that halothane > or = 1%, delivered during 4 h by mechanical ventilation, but not mechanical ventilation per se, alters the early LPS-induced lung inflammation in the rat, suggesting a specific effect of halothane on this response.

Cardiopulmonary bypass decreases cytokine production in lipopolysaccharide-stimulated whole blood cells: roles of interleukin-10 and the extracorporeal circuit.

OBJECTIVE: To determine whether cardiopulmonary bypass (CPB) alters the ex vivo cytokine production of whole blood cells stimulated by lipopolysaccharide (LPS) and to assess the roles of interleukin (IL)-10 and an extracorporeal circuit (ECC) in the alteration. DESIGN: Prospective, controlled study. SETTING: Biochemistry laboratory and surgical intensive care unit in a university hospital. PATIENTS: Seventeen consecutive adult patients undergoing coronary artery bypass grafting or valve surgery with normothermic CPB and eight healthy volunteers. INTERVENTIONS: Blood samples for cytokine measurement were drawn from patients before and during (at 60, 90, 120, 180 and 360 mins) CPB and were cultured with and without LPS and with and without anti-IL-10 antibodies. Blood was also drawn from healthy subjects and sampled for cytokine analysis before and during circulation in an isolated ECC. MEASUREMENTS AND MAIN RESULTS: The concentrations of ex vivo tumor necrosis factor (TNF)-alpha, IL-6, IL-8, and IL-10, measured by enzyme-linked immunosorbent assay, were reduced in both experimental settings. In patients on CPB, LPS hyporesponsiveness was detected at 60 mins after the onset of CPB and was maximal at 120 mins (78% to 86% decreases from pre-CPB levels) but was transient, except for TNF-alpha. The plasma concentration of IL-10 peaked at 90 mins after the start of CPB, but the role of IL-10 in LPS hyporesponsiveness appears limited because anti-IL-10 antibodies significantly increased ex vivo production of IL-6 but not TNF-alpha or IL-8. In the isolated ECC study, no IL-10 was detected in plasma, yet the ex vivo production of the cytokines (except IL-8) was decreased (by 66% to 95%). CONCLUSION: Our results demonstrate the following: a) CPB induces an early and transient LPS hyporesponsiveness of whole blood as measured by cytokine production; b) IL-10 seems only partly involved in this process, and its role is restricted to an in vivo situation; and c) contact of blood with an ECC is sufficient to induce LPS hyporesponsiveness.