Katja Urban

Resveratrol Impairs the Release of Steroid-Resistant Inflammatory Cytokines from Human Airway Smooth Muscle Cells in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) therapy is complicated by corticosteroid resistance of the interleukin 8 (IL-8)-dependent and granulocyte macrophage-colony stimulating factor (GM-CSF)-dependent chronic airway inflammation, for whose establishment human airway smooth muscle cells (HASMCs) might be crucial. It is unclear whether the release of inflammatory mediators from HASMCs is modulated by cigarette smoking and is refractory to corticosteroids in COPD. Resveratrol, an antiaging drug with protective effects against lung cancer, might be an alternative to corticosteroids in COPD therapy. Vascular endothelial growth factor (VEGF) might offer protection from developing emphysema. We tested the following hypotheses for HASMCs: 1) smoking with or without airway obstruction modulates IL-8, GM-CSF, and VEGF release; and 2) corticosteroids, but not resveratrol, fail to inhibit cytokine release in COPD. Cytokine release from HASMCs exposed to tumor necrosis factor α (TNFα), dexamethasone, and/or resveratrol was measured via enzyme-linked immunosorbent assay and compared between nonsmokers (NS), smokers without COPD (S), and smokers with COPD (all n = 10). In response to TNFα, IL-8 release was increased, but GM-CSF and VEGF release was decreased in S and COPD compared with NS. Dexamethasone and resveratrol inhibited concentration-dependently TNFα-induced IL-8, GM-CSF, and VEGF release. For IL-8 and GM-CSF efficiency of dexamethasone was NS > S > COPD. That of resveratrol was NS = S = COPD for IL-8 and NS = S < COPD for GM-CSF. For VEGF the efficiency of dexamethasone was NS = S = COPD, and that of resveratrol was NS = S > COPD. All resveratrol effects were partially based on p38 mitogen-activated protein kinase blockade. In conclusion, smoking modulates cytokine release from HASMCs. Corticosteroid refractoriness of HASMCs in COPD is cytokine-dependent. Resveratrol might be superior to corticosteroids in COPD therapy, because it more efficiently reduces the release of inflammatory mediators and has limited effects on VEGF in COPD.

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.

The T-Helper Cell Type 1 Immune Response to Gram-Negative Bacterial Infections Is Impaired in COPD

RATIONALE The increased susceptibility to bacterial infections in chronic obstructive pulmonary disease (COPD) is critical for exacerbations. Toll-like receptor-4 (TLR4) detects bacteria via LPS and induces IFN-γ-based immune responses. The direct responsiveness of Th1 lymphocytes to LPS is disputed because they lack surface expression of the TLR4 coreceptor CD14. OBJECTIVES We hypothesized that the Th1-mediated adaptive immune response to bacterial infections is impaired in COPD. METHODS LPS-induced TLR4 expression and IFN-γ release in and from ex vivo-generated Th1 cells was compared among nonsmokers (n = 14), smokers without COPD (n = 13), and smokers with COPD (n = 25) via quantitative reverse transcription polymerase chain reaction, Western blot, and ELISA. TLR4 transfection experiments were performed to functionally link receptor to IFN-γ dysregulation in COPD. MEASUREMENTS AND MAIN RESULTS Short-chain LPS from Salmonella species and nontypeable Haemophilus influenzae and nontypeable Haemophilus influenzae whole-cell extract all induced TLR4 expression via TLR4/MyD88/IRAK/mitogen-activated protein-kinase signaling and IFN-γ release via TLR4/TRIF/IKKε/TBK1 signaling in Th1 cells of nonsmokers. These effects were all impaired in smokers with and without COPD. The LPS responses were partially dependent on soluble CD14 and correlated positively to lung-function parameters but negatively to cigarette smoking (pack-years). Endogenous MyD88/IRAK signaling antagonists were up-regulated in Th1 cells of smokers and COPD, and TLR4 overexpression in Th1 cells of COPD restored LPS-dependent IFN-γ release. CONCLUSIONS Th1 cells directly respond to short-chain LPS. Cigarette smoking suppresses Th1-mediated immune responses to gram-negative bacterial infections by interfering with MyD88/IRAK signaling thereby reducing LPS-induced TLR4 expression. This can explain the increased susceptibility to bacterial infections in COPD. Targeting TLR signaling might be useful to reduce exacerbation rates.

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.