Severe or therapy-resistant asthma is increasingly recognised as a major unmet need. A Task Force, supported by the European Respiratory Society and American Thoracic Society, reviewed the definition and provided recommendations and guidelines on the evaluation and treatment of severe asthma in children and adults.A literature review was performed, followed by discussion by an expert committee according to the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach for development of specific clinical recommendations.When the diagnosis of asthma is confirmed and comorbidities addressed, severe asthma is defined as asthma that requires treatment with high dose inhaled corticosteroids plus a second controller and/or systemic corticosteroids to prevent it from becoming “uncontrolled” or that remains “uncontrolled” despite this therapy. Severe asthma is a heterogeneous condition consisting of phenotypes such as eosinophilic asthma. Specific recommendations on the use of sputum eosinophil count and exhaled nitric oxide to guide therapy, as well as treatment with anti-IgE antibody, methotrexate, macrolide antibiotics, antifungal agents and bronchial thermoplasty are provided.Coordinated research efforts for improved phenotyping will provide safe and effective biomarker-driven approaches to severe asthma therapy.

Chronic obstructive pulmonary disease (COPD) is characterized by chronic airway inflammation that is greater in patients with advanced disease. We asked whether there is a link between the severity of disease and the reduction in histone deacetylase (HDAC) activity in the peripheral lung tissue of patients with COPD of varying severity. HDAC is a key molecule in the repression of production of proinflammatory cytokines in alveolar macrophages. HDAC activity and histone acetyltransferase (HAT) activity were determined in nuclear extracts of specimens of surgically resected lung tissue from nonsmokers without COPD, patients with COPD of varying severity, and patients with pneumonia or cystic fibrosis. Alveolar macrophages from nonsmokers, smokers, and patients with COPD and bronchial-biopsy specimens from nonsmokers, healthy smokers, patients with COPD, and those with mild asthma were also examined. Total RNA extracted from lung tissue and macrophages was used for quantitative reverse-transcriptase–polymerase-chain-reaction assay of HDAC1 through HDAC8 and interleukin-8. Expression of HDAC2 protein was quantified with the use of Western blotting. Histone-4 acetylation at the interleukin-8 promoter was evaluated with the use of a chromatin immunoprecipitation assay. Specimens of lung tissue obtained from patients with increasing clinical stages of COPD had graded reductions in HDAC activity and increases in interleukin-8 messenger RNA (mRNA) and histone-4 acetylation at the interleukin-8 promoter. The mRNA expression of HDAC2, HDAC5, and HDAC8 and expression of the HDAC2 protein were also lower in patients with increasing severity of disease. HDAC activity was decreased in patients with COPD, as compared with normal subjects, in both the macrophages and biopsy specimens, with no changes in HAT activity, whereas HAT activity was increased in biopsy specimens obtained from patients with asthma. Neither HAT activity nor HDAC activity was changed in lung tissue from patients with cystic fibrosis or pneumonia. Patients with COPD have a progressive reduction in total HDAC activity that reflects the severity of the disease.

Reactive oxygen species, either directly orviathe formation of lipid peroxidation products, may play a role in enhancing inflammation through the activation of stress kinases (c-Jun activated kinase, extracellular signal-regulated kinase, p38) and redox-sensitive transcription factors, such as nuclear factor (NF)-κB and activator protein-1. This results in increased expression of a battery of distinct pro-inflammatory mediators. Oxidative stress activates NF-κB-mediated transcription of pro-inflammatory mediators either through activation of its activating inhibitor of κB-α kinase or the enhanced recruitment and activation of transcriptional co-activators. Enhanced NF-κB-co-activator complex formation results in targeted increases in histone modifications, such as acetylation leading to inflammatory gene expression.Emerging evidence suggests the glutathione redox couple may entail dynamic regulation of protein function by reversible disulphide bond formation on kinases, phosphatases and transcription factors. Oxidative stress also inhibits histone deacetylase activity and in doing so further enhances inflammatory gene expression and may attenuate glucocorticoid sensitivity.The antioxidant/anti-inflammatory effects of thiol molecules (glutathione,N-acetyl-L-cysteine andN-acystelyn, erdosteine), dietary polyphenols (curcumin-diferuloylmethane, cathechins/quercetin and reserveratol), specific spin traps, such as α-phenyl-N-tert-butyl nitrone, a catalytic antioxidant (extracellular superoxide dismutase (SOD) mimetic, SOD mimetic M40419 and SOD, and catalase manganic salen compound, eukarion-8), porphyrins (AEOL 10150 and AEOL 10113) and theophylline have all been shown to play a role in either controlling NF-κB activation or affecting histone modifications with subsequent effects on inflammatory gene expression in lung epithelial cells.Thus, oxidative stress regulates both key signal transduction pathways and histone modifications involved in lung inflammation. Various approaches to enhance lung antioxidant capacity and clinical trials of antioxidant compounds in chronic obstructive pulmonary disease are also discussed.

We have investigated the ability of dexamethasone to regulate interleukin-1β (IL-1β)-induced gene expression, histone acetyltransferase (HAT) and histone deacetylase (HDAC) activity. Low concentrations of dexamethasone (10⁻¹⁰ M) repress IL-1β-stimulated granulocyte-macrophage colony-stimulating factor (GM-CSF) expression and fail to stimulate secretory leukocyte proteinase inhibitor expression. Dexamethasone (10⁻⁷ M) and IL-1β (1 ng/ml) both stimulated HAT activity but showed a different pattern of histone H4 acetylation. Dexamethasone targeted lysines K5 and K16, whereas IL-1β targeted K8 and K12. Low concentrations of dexamethasone (10⁻¹⁰ M), which do not transactivate, repressed IL-1β-stimulated K8 and K12 acetylation. Using chromatin immunoprecipitation assays, we show that dexamethasone inhibits IL-1β-enhanced acetylated K8-associated GM-CSF promoter enrichment in a concentration-dependent manner. Neither IL-1β nor dexamethasone elicited any GM-CSF promoter association at acetylated K5 residues. Furthermore, we show that GR acts both as a direct inhibitor of CREB binding protein (CBP)-associated HAT activity and also by recruiting HDAC2 to the p65-CBP HAT complex. This action does not involve de novo synthesis of HDAC protein or altered expression of CBP or p300/CBP-associated factor. This mechanism for glucocorticoid repression is novel and establishes that inhibition of histone acetylation is an additional level of control of inflammatory gene expression. This further suggests that pharmacological manipulation of of specific histone acetylation status is a potentially useful approach for the treatment of inflammatory diseases.