Future therapeutic treatment of COPD: Struggle between oxidants and cytokines

Chronic obstructive pulmonary disease (COPD) is a global health problem. Being a progressive disease characterized by inflammation and predominantly caused by tobacco smoking, it deteriorates pulmonary and skeletal muscle functioning, and reduces physical behavior, societal participation and quality of life. During the last two decades studies were focused on the airway and systemic inflammation, oxidative stress, and airway and/or parenchymal remodeling. Macrophages, neutrophils and T cells are thought to be important key players, as well as structural cells like fibroblasts, epithelial, endothelial and smooth muscle cells. Mediators and proteins including cytokines, chemokines, growth factors, proteinases, and oxidants seem to be involved differentially in its pathogenesis. Current pharmacological treatments are directed to reducing airway inflammation, boosting the endogenous levels of anti-oxidants and relieving airway contraction and sputum production. Most agents were primarily used for treating asthma. But in contrast to asthma, these treatments are not very effective in COPD. As a result, novel more specifically acting interventional drugs with less side effects are being developed to treat chronic inflammatory diseases, including COPD. This review highlights studies on novel or potential drug antioxidants such as dietary antioxidants supplementation, N-acetyl-L-cysteine, N-acystelyn, endosteine, antioxidant enzyme mimetics, and anti-inflammatory agents like antagonists of cytokines, such as tumor necrosis factor (TNF)-α, CXCL8, and CCL2, and inhibitors of signal transduction proteins including phosphodiesterase 4, MAPK p38, Pl-3k, and NFκB.     

The effects of cigarette smoke on airway inflammation in asthma and COPD: therapeutic implications

Asthma and COPD are two chronic inflammatory disorders of the airway characterized by airflow limitation. While many similarities exist between these two diseases, they are pathologically distinct due to the involvement of different inflammatory cells; predominantly neutrophils, CD8 lymphocytes in COPD and eosinophils and CD4 lymphocytes in asthma. Cigarette smoking is associated with accelerated decline of lung function, increased mortality, and worsening of symptoms in both asthma and COPD. Furthermore, exposure to cigarette smoke can alter the inflammatory mechanisms in asthma to become similar to that seen in COPD with increasing CD8 cells and neutrophils and may therefore alter the response to therapy. Cigarette smoke exposure has been associated with a poor response to inhaled corticosteroids which are recommended as first line anti-inflammatory medications in asthma and as an add-on therapy in patients with severe COPD with history of exacerbations. While the main proposed mechanism for this altered response is the reduction of the histone deacetylase 2 (HDAC2) enzyme system, other possible mechanisms include the overexpression of GR-β, activation of p38 MAPK pathway and increased production of inflammatory cytokines such as IL-2, 4, 8, TNF-α and NF-K?. Few clinical trials suggest that leukotriene modifiers may be an alternative to corticosteroids in smokers with asthma but there are currently no drugs which effectively reduce the progression of inflammation in smokers with COPD. However, several HDAC2 enhancers including low dose theophylline and other potential anti-inflammatory therapies including PDE4 inhibitors and p38 MAPK inhibitors are being evaluated.     

Melatonin inhibits MUC5AC production via suppression of MAPK signaling in human airway epithelial cells

Mucus acts as a primary defense system in the airway against various stimuli. However, excess mucus production causes a reduction in lung function via limitation of the airflow in the airway of patients suffering from asthma or chronic obstructive pulmonary disease (COPD). In this study, we evaluated the effects of melatonin on the production of MUC5AC, a major constituent of the mucin that is secreted from the airway, using epidermal growth factor (EGF)‐stimulated NCI‐H292 cells, a human mucoepidermoid carcinoma cell line, and an ovalbumin (OVA)‐induced asthma murine model. Melatonin treatment significantly reduced the mRNA and protein levels of MUC5AC and reduced interleukin (IL)‐6 production in EGF‐stimulated H292 cells. Melatonin markedly decreased the phosphorylation of MAPKs, including ERK1/2, JNK, and p‐38, induced by EGF stimulation. These findings were consistent with the results using MAPK inhibitors. Particularly, co‐treatment with melatonin and a MAPK inhibitor more effectively suppressed MAPK phosphorylation than treatment with a MAPK inhibitor alone, which resulted in a reduction in MUC5AC expression. In the asthma murine model, melatonin‐treated mice exhibited a marked reduction in MUC5AC expression in the airway compared with the OVA‐induced mice. These reductions were accompanied by reductions in proinflammatory cytokine production and inflammatory cell infiltration. Collectively, these findings indicate that melatonin effectively inhibits MUC5AC expression. These effects may be closely associated with the inhibition of MAPK phosphorylation. Furthermore, our study suggests that melatonin could represent a potential therapeutic for chronic airway diseases, such as asthma and COPD.     

8-isoprostane increases expression of interleukin-8 in human macrophages through activation of mitogen-activated protein kinases

BACKGROUND AND OBJECTIVES: 8-isoprostane is a marker of oxidative stress in vivo and increased plasma and urine levels are found in patients with vascular disease and in atherosclerotic plaques. Inflammatory chemokines such as interleukin (IL)-8 seem to play an important pathogenic role in atherogenesis. We therefore investigated the effects of 8-isoprostane on the expression of inflammatory chemokines with consciousness on IL-8 (mRNA and protein) in human macrophages. In addition, we studied the involvement of mitogen-activated protein kinases (ERK 1/2 and p38 MAPK) and nuclear factor-kappaB (NF-kappaB) in this process. METHODS AND RESULTS: 8-isoprostane (10 microM) induced IL-8 expression (mRNA and protein), measured by real-time quantitative RT-PCR and enzyme immunoassay, respectively, in both THP-1 macrophages and human monocyte-derived macrophages. Moreover, 8-isoprostane increased mRNA expression of macrophage inflammatory protein-1alpha as determined by RNase protection assay. In this process, 8-isoprostane induced the activation of two major MAP-kinases; ERK 1/2 and p38 MAPK. Furthermore, the ERK 1/2 inhibitor, PD98059, and the p38 MAPK inhibitor, SB203580, markedly reduced 8-isoprostane-induced IL-8 expression (mRNA and protein), while inhibition of NF-kappaB activation and translocation had no significant effect on IL-8 expression. CONCLUSIONS: We show that 8-isoprostane increases IL-8 expression in human macrophages involving both ERK 1/2 and p38 MAPK, but not NF-kappaB signaling pathway. These findings further support a link between oxidative stress/lipid peroxidation and inflammation in human macrophages and suggest a role for 8-isoprostane in this process. This 8-isoprostane-induced chemokine expression might be involved in the pathogenesis of atherosclerosis as well as other inflammatory disorders.     

Integrins play a critical role in mechanical stress-induced p38 MAPK activation

Mechanical stress activates various hypertrophic responses, including activation of mitogen-activated protein kinases (MAPKs) in cardiac myocytes. Stretch activated extracellular signal-regulated kinases partly through secreted humoral growth factors, including angiotensin II, whereas stretch-induced activation of c-Jun NH(2)-terminal kinases and p38 MAPK was independent of angiotensin II. In this study, we examined the role of integrin signaling in stretch-induced activation of p38 MAPK in cardiomyocytes of neonatal rats. Overexpression of the tumor suppressor PTEN, which inhibits outside-in integrin signaling, strongly suppressed stretch-induced activation of p38 MAPK. Overexpression of focal adhesion kinase (FAK) antagonized the effects of PTEN, and both tyrosine residues at 397 and 925 of FAK were necessary for its effects. Stretch induced tyrosine phosphorylation and activation of FAK and Src. Stretch-induced activation of p38 MAPK was abolished by overexpression of FAT and CSK, which are inhibitors of the FAK and Src families, respectively, and was suppressed by overexpression of a dominant-negative mutant of Ras. Mechanical stretch-induced increase in protein synthesis was suppressed by SB202190, a p38 MAPK inhibitor. These results suggest that mechanical stress activates p38 MAPK and induces cardiac hypertrophy through the integrin-FAK-Src-Ras pathway in cardiac myocytes.     

p38丝裂原活化蛋白激酶与慢性气道疾病

支气管哮喘和慢性阻塞性肺疾病是两大主要的慢性气道疾病.作为一种细胞内信号转导通路,p38丝裂原活化蛋白激酶(MAPK)介导基因表达、炎性因子产生,在炎性细胞的增殖、分化、凋亡等方面扮有关键性作用,参与慢性气道疾病的气道炎症机制.体外实验表明p38 MAPK抑制剂有抗炎作用,动物实验表明p38 MAPK抑制剂可有效抑制慢性气道疾病模型的气道炎症、气道高反应性和重塑.此外,p38 MAPK的活性异常还与激素不敏感密切相关,p38 MAPK抑制剂可提高激素的抗炎效应.     

Anti‐inflammatory effects of exendin‐4, a glucagon‐like peptide‐1 analog,on human peripheral lymphocytes in patients with type 2 diabetes

Aims/Introduction

Type 2 diabetes is characterized by dysregulation of immunity, oxidative stress and reduced incretin effects. Experimental studies suggest that glucagon‐like peptide (GLP‐1) might have immunomodulating effects. We hypothesize that GLP‐1 receptor agonist, exendin‐4, might reduce inflammatory response in type 2 diabetes.

Materials and Methods

Using peripheral blood mononuclear cells (PBMC) sampled from 10 type 2 diabetes and 10 sex‐ and age‐matched control subjects and supernatants from PBMC culture, the expression of phospho‐mitogen activated protein kinase (MAPK) signaling pathways in CD4+ T helper lymphocytes and monocytes was analyzed using flow cytometry. Cytokines/chemokines and superoxide anion before and after treatment with exendin‐4 were measured by cytometric bead array and chemiluminesence assay, respectively.

Results

Compared with control subjects, PBMC from type 2 diabetes patients showed activated MAPK (P38, c‐Jun NH2‐terminal protein kinase and extracellular signal‐regulated kinase) signaling pathway, elevated superoxide anion, increased pro‐inflammatory cytokines (tumor necrosis factor‐α, interleukin‐1β, interleukin‐6) and chemokines (CCL5/regulated on activation normal T‐cell expressed and secreted and CXCL10/interferon‐γ‐induced protein 10). These changes were attenuated by exendin‐4, possibly through the suppression of p38 MAPK.

Conclusions

These results suggest that exendin‐4 might downregulate pro‐inflammatory responses and reduce oxidative stress by suppressing MAPK signaling pathways in type 2 diabetes.     

酪氨酸激酶信号级联与支气管哮喘发病的关系

支气管哮喘的发病机制涉及炎症细胞和气道结构细胞、细胞因子、趋化因子、生长因子和炎症介质的相互作用.酪氨酸激酶信号级联在变应性气道炎症中起重要作用,活化的酪氨酸激酶激活了多重下游信号转导途径如磷酯酰肌醇3激酶、丝裂原活化蛋白激酶和核因子κB,导致细胞的分化、存活、增殖、脱颗粒和趋化.     

p38 MAPK inhibition alleviates experimental acute pancreatitis in mice

BACKGROUND: The mitogen-activated protein kinases (MAPKs) signaling pathway is involved in inflammatory process. However,the mechanism is not clear. The present study was to investigate the role of p38 MAPK in acute pancreatitis in mice.METHODS: Mice were divided into 4 groups: saline control; acute pancreatitis induced with repeated injections of cerulein; control plus p38 MAPK inhibitor SB203580; and acute pancreatitis plus SB203580. The pancreatic histology, pancreatic enzymes, cytokines, myeloperoxidase activity, p38 MAPK and heat shock protein (HSP) 60 and 70 were evaluated.RESULTS: Repeated injections of cerulein resulted in acute pancreatitis in mice, accompanying with the activation of p38 MAPK and overexpression of HSP60 and HSP70 in the pancreatic tissues. Treatment with SB203580 significantly inhibited the activation of p38 MAPK, and furthermore, inhibited the expression of HSP60 and HSP70 in the pancreas, the inflammatory cytokines in the serum, and myeloperoxidase activity in the lung.CONCLUSION: The p38 MAPK signaling pathway is involved in the regulation of inflammatory response and the expression of HSP60 and HSP70 in acute pancreatitis.     

Inhaled p38alpha mitogen-activated protein kinase antisense oligonucleotide attenuates asthma in mice

The p38 mitogen-activated protein kinase (MAPK) plays a critical role in the activation of inflammatory cells. Therefore, we investigated the antiinflammatory effects of a respirable p38alpha MAPK antisense oligonucleotide (p38alpha-ASO) in a mouse asthma model. A potent and selective p38alpha-ASO was characterized in vitro. Inhalation of aerosolized p38alpha-ASO using an aerosol chamber dosing system produced measurable lung deposition of ASO and significant reduction of ovalbumin (OVA-)-induced increases in total cells, eosinophils, and interleukin 4 (IL-4), IL-5, and IL-13 levels in bronchoalveolar lavage fluid, and dose-dependent inhibition of airway hyperresponsiveness in allergen-challenged mice. Furthermore, inhaled p38alpha-ASO markedly inhibited OVA-induced lung tissue eosinophilia and airway mucus hypersecretion. Quantitative polymerase chain reaction analysis of bronchoalveolar lavage fluid cells and peribronchial lymph node cells showed that p38alpha-ASO significantly reduced p38alpha MAPK mRNA expression. Nose-only aerosol exposure of mice verified the p38alpha-ASO-induced inhibition of OVA-induced pulmonary eosinophilia, mucus hypersecretion, and airway hyperresponsiveness. None of the effects of the p38alpha-ASO were produced by a six-base mismatched control oligonucleotide. These findings demonstrate antisense pharmacodynamic activity in the airways after aerosol delivery and suggest that a p38alpha MAPK ASO approach may have therapeutic potential for asthma and other inflammatory lung diseases.     

pH in expired breath condensate of patients with inflammatory airway diseases

Endogenous airway acidification, as assessed by pH in expired breath condensate, has been implicated in asthma pathophysiology. We measured pH in breath condensate of patients with inflammatory airway diseases in stable condition and examined its relationship with the inflammatory process (as assessed by differential cell counts in induced sputum), oxidative stress (as assessed by H(2)O(2) and 8-isoprostane), and nitric oxide metabolism (as assessed by total nitrate/nitrite). We studied 40 patients with bronchial asthma (20 with moderate disease, forced expiratory volume in 1 second 60 [10]% SD predicted), 20 patients with bronchiectasis, 20 patients with chronic obstructive pulmonary disease (COPD), and 10 normal subjects. Mean (95% confidence intervals) pH values were significantly lower in patients with COPD and bronchiectasis compared with patients with asthma and control subjects (7.16, 7.09-7.23 and 7.11, 7.04-7.19 versus 7.43, 7.35-7.52 and 7.57, 7.51-7.64, respectively, p < 0.0001). Patients with moderate asthma had significantly lower values compared with mild and control subjects. In patients with COPD and bronchiectasis, the values of pH were significantly correlated with both sputum neutrophilia and oxidative stress. Respectively, in patients with moderate asthma, a significant correlation was observed between pH and sputum eosinophilia, total nitrate/nitrite, and oxidative stress. The pH of the expired breath condensate might be a simple, noninvasive, inexpensive, and easily repeatable procedure for the evaluation of the inflammatory process in airway diseases.     

Oxidative stress and hepatitis C viral infection.

The involvement of oxidative stress in the pathogenesis of hepatitis and hepatocellular carcinoma has been strongly suggested. Oxidative stress is produced by inflammatory processes that occur in hepatitis via immunological mechanisms. In addition, in hepatitis C virus (HCV) infectious disease, some role has been assigned to viral proteins in the induction of oxidative stress. In the presence of hepatic steatosis, insulin resistance and increased levels of some cytokines, all of which are also induced by viral protein expression, oxidative stress is enhanced in HCV infection. In this sense, the role of oxidative stress in the progression of chronic hepatitis and hepatocarcinogenesis is greater in hepatitis C than in other types of hepatitis such as hepatitis B or autoimmune hepatitis. The additive effects of oxidative stress caused by the inflammatory process and that induced by HCV proteins may, furthermore, exert synergistic effects with alterations in intracellular signaling systems such as mitogen-activated protein kinases (MAPK), which are also induced by HCV proteins. These synergistic effects may be responsible for rare characteristics, that is, the high incidence and multicentric nature of hepatocarcinogenesis in HCV infection.     

慢性阻塞性肺疾病患者p38蛋白激酶表达的变化及其临床意义

目的探讨慢性阻塞性肺疾病(COPD)患者诱导痰中p38蛋白激酶(p38MAPK)表达的变化及其临床意义。方法选择COPD急性加重期患者29例、稳定期患者18例及健康对照者15例。3%～5%氯化钠注射液进行痰液诱导,计数诱导痰中细胞总数、细胞分类。分别采用蛋白质免疫印迹、ELISA方法检测诱导痰中细胞核蛋白p38MAPK含量和上清液中IL-8的含量。结果与健康对照者比较,COPD患者诱导痰中细胞总数、中性粒细胞比例、p38MAPK的表达和上清液IL-8浓度明显升高,FEV1%显著降低(P<0.05);各组诱导痰中细胞核蛋白p38 MAPK的表达与上清液IL-8浓度和中性粒细胞比例均呈正相关(r=0.531,0.664,P<0.01),与FEV1呈负相关(r=-0.468,P<0.05)。结论 COPD患者诱导痰中p38 MAPK表达增高,可能与COPD气道炎症发生发展密切相关。     

Corticosteroid resistance in airway disease

Resistance to the antiinflammatory effects of corticosteroids is very uncommon in asthma but common in chronic obstructive pulmonary disease. Recent understanding of the molecular mechanisms involved in the antiinflammatory actions of corticosteroids has revealed that there are several possible mechanisms for corticosteroid resistance. Certain cytokines activate p38 mitogen-activated protein kinase, which may interfere with the nuclear localization of glucocorticoid receptors (GRs). In other patients, nuclear localization of GR is normal but there is a reduction in acetylation of a lysine residue in histone-4, thus leading to impaired activation of certain antiinflammatory genes. In chronic obstructive pulmonary disease and severe asthma, oxidative stress may reduce the activity and expression of certain histone deacetylases and therefore interfere with the antiinflammatory action of corticosteroids. These mechanisms suggest that there may be several therapeutic approaches to treating corticosteroid resistance in the future, including antioxidants, p38 mitogen-activated protein kinase inhibitors, and theophylline, which activates histone deacetylases.     

Human airway smooth muscle cells express eotaxin in response to signaling following mast cell contact

BACKGROUND: Asthma is a chronic inflammatory disease of the airways. Mast-cell (MC)-derived cytokines may mediate both airway inflammation and remodeling. It has also been shown that airway smooth muscle cells (ASMC) can be a source of proinflammatory cytokines. In the human airways, MC-ASMC cell interactions may have pivotal effects on modulating inflammation. OBJECTIVES: We wanted to know whether the production of eotaxin, an important proinflammatory cytokine, through a cell-to-cell contact mechanism of human ASMC activation by MC was mediated by p38 MAPK. METHODS: We cocultured normal humanASMC with a human MC line (HMC-1) and assayed for the production of eotaxin. RESULTS: When cultured together, human ASMC and HMC-1 contact induced eotaxin secretion. Separation of HMC-1 and human ASMC by a porous membrane inhibited this induction. Coculturing of human ASMC with HMC-1 induced increased expression of eotaxin gene mRNA. HMC-1-derived cellular membranes caused an increase in eotaxin production in human ASMC. Activation of p38 MAPK was also seen in cocultures by Western blot, whereas eotaxin production in cocultures was significantly inhibited by the p38 inhibitor SB203580. CONCLUSION: These novel studies reveal the importance of cell-to-cell interactions in the complex milieu of airway inflammation.     

Peptostreptococcus micros cell wall elicits a pro-inflammatory response in human macrophages

Peptostreptococcus micros is a Gram-positive anaerobic bacterium associated with periodontitis, a chronic inflammatory disease affecting tooth-supporting tissues. In the present study, we investigated the response of human macrophages to stimulation with a cell wall preparation from P. micros. In addition, the effect of the preparation on the phosphorylation of macrophage kinases was studied. The preparation, which was non-toxic for macrophages, significantly increased the secretion of the pro-inflammatory cytokines TNF-alpha, IL-1beta and IL-6. It also increased the secretion of two potent chemokines IL-8 and, to a lesser extent, RANTES. Lastly, stimulation of macrophages by the P. micros cell wall preparation induced a significant increase in MMP-9 secretion but had no effect on the production of prostaglandin E2. The phosphorylation of macrophage kinases, including cAMP-dependent protein-serine kinase (PKA) catalytic subunit beta, G protein-coupled receptor-serine kinase 2, mitogen-activated protein-serine kinase p38 alpha (p38a MAPK), extracellular regulated protein-serine kinase 2 (ERK2) and Jun N-terminus protein-serine kinases (JNK), increased following stimulation with cell wall. In summary, our study showed that the P. micros cell wall preparation induced intracellular signaling pathways, leading to an increased production of pro-inflammatory cytokines, chemokines and MMP-9 by macrophages.