Andrea Koch

Resveratrol Impairs the Release of Steroid‐resistant Cytokines from Bacterial Endotoxin‐Exposed Alveolar Macrophages in Chronic Obstructive Pulmonary Disease

Airway inflammation in chronic obstructive pulmonary disease (COPD) is believed to be insensitive to corticosteroids. However, corticosteroids are recommended in COPD (GOLD stages III, IV) with frequent exacerbations. Resveratrol has anti-inflammatory properties and could be an alternative to corticosteroids in COPD therapy. We investigated the effect of dexamethasone versus resveratrol on the release of COPD-related inflammatory mediators (IL-6, IL-8, GM-CSF and MCP-1) and matrix-metalloprotease-9 (MMP-9) from alveolar macrophages exposed to gram-negative bacterial endotoxin (lipopolysaccharide, LPS). We compared never-smokers, current smokers without airway obstruction and current smokers with COPD. The cytokines and MMP-9 were measured in cell culture supernatants with ELISA. The release of IL-8 and MMP-9 from LPS-exposed alveolar macrophages was increased in COPD, the release of GM-CSF and IL-6 was decreased in COPD and the release of MCP-1 was without differences between the cohorts. Dexamethasone impaired the release of all cytokines and MMP-9 from LPS-exposed alveolar macrophages of all cohorts, but for IL-8 and GM-CSF this effect was reduced in COPD. In alveolar macrophages of COPD, there was an almost complete reduction in IL-6 release but only a partial reduction in IL-8, GM-CSF, MCP-1 and MMP-9 release demonstrating a partial corticosteroid-insensitivity. In contrast, resveratrol almost completely reduced the release of all cytokines and MMP-9 without significant differences between the cohorts. Our data provide evidence for a corticosteroid resistance of alveolar macrophage-dependent inflammatory responses induced by gram-negative bacteria in COPD and thus question the utility of corticosteroids in COPD therapy. Instead, resveratrol may prove an alternative.

TNFα-induced GM-CSF Release from Human Airway Smooth Muscle Cells Depends on Activation of an ET-1 Autoregulatory Positive Feedback Mechanism

Background: There is an urgent need to inhibit endothelin-1 (ET-1) induced chronic inflammatory processes in early stages of lung diseases in order to prevent untreatable irreversible stages often accompanied by lung fibrosis and pulmonary hypertension. Nothing is known about the airway inflammation-inducing and/or maintaining role of ET-1 in human airway smooth muscle cells (HASMCs). Objective: ET-1 and granulocyte–macrophage colony-stimulating factor (GM-CSF) expression in response to tumour necrosis factor α (TNFα) and ET-1 stimulation was investigated, and the impact of mitogen-activated protein kinase (MAPK) pathways in this context was studied. To elucidate the anti-inflammatory properties of the dual endothelin receptor antagonist bosentan that targets both endothelin receptor subtypes A (ETAR) and B (ETBR), its effect on the TNFα/ET-1/GM-CSF network was investigated. Methods: ET-1 and GM-CSF expression and activation of MAPKs were investigated via quantitative reverse transcription-PCR (RT-PCR), western blotting and ELISA. Main results: Both TNFα and ET-1 activated p38MAPK and extracellular signal-regulated kinase (ERK)-1/-2 signalling. ET-1 expression was induced by TNFα and by ET-1 itself. Both effects were inhibited by bosentan and by specific ETAR or p38MAPK blockade. ET-1- and TNFα-induced GM-CSF expression were both reduced by bosentan as well as by specific inhibition of either ETAR, ETBR, p38MAPK or ERK-1/-2. Conclusion: TNFα activates an ETAR- and p38MAPK-dependent ET-1 autoregulatory positive feedback loop to maintain GM-CSF release from HASMCs. Since bosentan impairs ET-1 autoregulation and TNFα-induced ET-1 release, as well as TNFα- and ET-1-induced GM-CSF release, the present data suggest therapeutic utility for bosentan in treating particularly the early stages of chronic inflammatory airway diseases.

Enhanced sensitivity of the failing human myocardium to cardiac glycosides and Na+-channel activators

Cardiac glycosides and Na+ -channel activators increase intracellular Na+ and thereby enhance the transport rate of the sarcolemmal Na+/Ca2+ exchanger. We tested the hypothesis of whether increased expression of the Na+/Ca2+ exchanger in failing human myocardium is accompanied by enhanced sensitivity of the failing human myocardium toward cardiac glycosides and Na+ -channel activators. We studied the positive inotropic effects of the new Na+ -channel activator BDF and the cardiac glycoside ouabain in human failing (New York Heart Association [NYHA] functional class IV, heart transplants for dilated cardiomyopathy, n = 11) and nonfailing (donor hearts, n = 5) myocardium on electrically driven left ventricular papillary muscle strips (1 Hz, 37 degrees C). The effectiveness of ouabain and BDF to increase force of contraction was similar in human nonfailing and failing myocardium. BDF was more potent to increase force of contraction in failing than in nonfailing tissue (p < 0.05). The time until maximal inotropic effect developed after ouabain was significantly shorter in NYHA IV (mean 150 +/- 16 min) than in nonfailing myocardium (mean 240 +/- 20 min). These results suggest that human failing myocardium exerts and enhanced sensitivity to cardiac glycosides and Na+ -channel activators, possibly because of enhanced expression of the Na+/Ca2+ exchanger or because of an altered intracellular Na+ -homeostasis.

Measuring in Situ Central Airway Resistance in Patients With Laryngotracheal Stenosis

Objectives: To evaluate a newly developed bronchoscopic technique for the assessment of intratracheal pressures.

Effect of lipoteichoic acid on IL-2 and IL-5 release from T lymphocytes in asthma and COPD

Susceptibility to infections with gram-positive bacteria, which are an important trigger of exacerbations, is increased in COPD and asthma. Unraveling the underlying mechanisms may help developing therapeutic strategies to reduce exacerbation rates. The aim of this study was to evaluate the effects of lipoteichoic acid (LTA), a danger signal from gram-positive bacteria, on T cell cytokines related to bacterial infection defense in COPD and asthma. T cell populations within peripheral blood mononuclear cells (PBMCs) were ex-vivo activated towards T(H)2/T(C)2 subtypes and subsequently stimulated with LTA. IL-2 and IL-5 concentrations in cell culture supernatants were measured by ELISA comparative between non-smokers (NS), current smokers without airflow limitation (S), smokers with moderate to severe COPD and mild to moderate asthmatics (A) (each n=10). IL-2 and IL-5 baseline levels were without differences between the cohorts. After T cell activation, IL-2 and IL-5 releases were increased in all cohorts, however, for IL-2 this increase was significantly higher in S and by trend in COPD compared to the other groups. LTA time-dependently suppressed IL-2 release in NS, S and COPD but not in A. LTA reduced IL-5 release in COPD and A but not in NS and S. Summarized, LTA reduces T(H)2/T(C)2 cytokines indicating immunosuppressive effects, which are dysregulated in COPD and asthma. This implies a misguided response to gram-positive bacterial infections, which might help to explain the increased susceptibility to bacterial infections in COPD and asthma.

IL-5 release of CD4+ non-effector lymphocytes is increased in COPD--modulating effects of moxifloxacin and dexamethasone.

T-lymphocytes are crucial in chronic obstructive pulmonary disease (COPD) pathogenesis. Especially T(H)1-lymphocytes are involved in local and systemic inflammation in COPD, yet the role of T(H)2-mediated immune-responses in COPD pathogenesis is poorly understood. The objective of this study was to examine IL-5 expression in T(H)2-lymphocytes in smokers with and without COPD ex vivo compared with non-smokers and to evaluate the effects of bacterial endotoxin (lipopolysaccharide, LPS) as well as two drugs often used for treatment of COPD exacerbation, corticosteroids and moxifloxacin. CD4(+) lymphocytes were isolated from the peripheral blood of non-smokers (NS; n=11), current smokers without airflow limitation (S; n=11) and smokers with COPD (n=11). Baseline IL-5 release of CD4(+) T-lymphocytes was significantly increased in COPD compared to S and NS. After T-cell activation and differentiation into T(H)2-lymphocytes, IL-5 release increased without differences between the cohorts. LPS reduced IL-5 release of ex vivo generated T(H)2-lymphocytes without differences in all cohorts. Moxifloxacin and dexamethasone significantly reduced IL-5 release in T(H)2-lymphocytes in the absence and presence of LPS without differences between groups. In summary, our data indicate that IL-5 might contribute to systemic inflammation in smokers with COPD and that T(H)2-based immune responses might be suppressed in response to gram-negative bacterial infections independent from smoking and disease status. Dexamethasone and moxifloxacin both have T(H)2-immunmodulating effects.

Simvastatin requires activation in accessory cells to modulate T-cell responses in asthma and COPD.

T-cell-dependent airway and systemic inflammation triggers the progression of chronic obstructive pulmonary disease (COPD) and asthma. Retrospective studies suggest that simvastatin has anti-inflammatory effects in both diseases but it is unclear, which cell types are targeted. We hypothesized that simvastatin modulates T-cell activity. Circulating CD4+ and CD8+ T-cells, either pure, co-cultured with monocytes or alveolar macrophages (AM) or in peripheral blood mononuclear cells (PBMCs), were ex vivo activated towards Th1/Tc1 or Th2/Tc2 and incubated with simvastatin. Markers for Th1/Tc1 (IFNγ) and Th2/Tc2 (IL-5, IL-13) were measured by ELISA; with PBMCs this was done comparative between 11 healthy never-smokers, 11 current smokers without airflow limitation, 14 smokers with COPD and 11 never-smokers with atopic asthma. T-cell activation induced IFNγ, IL-5 and IL-13 in the presence and absence of accessory cells. Simvastatin did not modulate cytokine expression in pure T-cell fractions. β-hydroxy-simvastatin acid (activated simvastatin) suppressed IL-5 and IL-13 in pure Th2- and Tc2-cells. Simvastatin suppressed IL-5 and IL-13 in Th2-cells co-cultivated with monocytes or AM, which was partially reversed by the carboxylesterase inhibitor benzil. Simvastatin suppressed IL-5 production of Th2/Tc2-cells in PBMCs without differences between cohorts and IL-13 stronger in never-smokers and asthma compared to COPD. Simvastatin induced IFNγ in Th1/Tc1-cells in PBMCs of all cohorts except asthmatics. Simvastatin requires activation in accessory cells likely by carboxylesterase to suppress IL-5 and IL-13 in Th2/Tc2-cells. The effects on Il-13 are partially reduced in COPD. Asthma pathogenesis prevents simvastatin-induced IFNγ up-regulation. Simvastatin has anti-inflammatory effects that could be of interest for asthma therapy.