Asthma treatments: new and emerging therapies

Airway Redox Homeostasis and Inflammation Gone Awry: From Molecular Pathogenesis to Emerging Therapeutics in Respiratory Pathology

As aerobic organisms, we are continuously and throughout our lifetime subjected to an oxidizing atmosphere and, most often, to environmental threats. The lung is the internal organ most highly exposed to this milieu. Therefore, it has evolved to confront both oxidative stress induced by reactive oxygen species (ROS) and a variety of pollutants, pathogens, and allergens that promote inflammation and can harm the airways to different degrees. Indeed, an excess of ROS, generated intrinsically or from external sources, can imprint direct damage to key structural cell components (nucleic acids, sugars, lipids, and proteins) and indirectly perturb ROS-mediated signaling in lung epithelia, impairing its homeostasis. These early events complemented with efficient recognition of pathogen- or damage-associated recognition patterns by the airway resident cells alert the immune system, which mounts an inflammatory response to remove the hazards, including collateral dead cells and cellular debris, in an attempt to return to homeostatic conditions. Thus, any major or chronic dysregulation of the redox balance, the air-liquid interface, or defects in epithelial proteins impairing mucociliary clearance or other defense systems may lead to airway damage. Here, we review our understanding of the key role of oxidative stress and inflammation in respiratory pathology, and extensively report current and future trends in antioxidant and anti-inflammatory treatments focusing on the following major acute and chronic lung diseases: acute lung injury/respiratory distress syndrome, asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, and cystic fibrosis.

Identification of surrogate prognostic biomarkers for allergic asthma in nasal epithelial brushing samples by WGCNA

BACKGROUND

Allergic asthma is a lower respiratory tract disease of Th2 inflammation with multiple molecular mechanisms. The upper and lower airways can be unified by the concept of a united airway and, as such, gene expression studies of upper epithelial cells may provide effective surrogate biomarkers for the prognostic study of allergic asthma.

OBJECTIVE

To identify surrogate biomarkers in upper airway epithelial cells for the prognostic study of allergic asthma.

METHODS

Nasal epithelial cell gene expression in 40 asthmatic and 17 healthy control subjects were analyzed by weighted gene coexpression network analysis (WGCNA) to identify gene network modules and profiles in allergic asthma. Functional enrichment analysis was performed on the coexpression genes in certain highlighted modules.

RESULTS

A total of 13 coexpression modules were constructed by WGCNA from 2804 genes in nasal epithelial brushing samples of the 40 asthmatic and 17 healthy subjects. The number of genes in these modules ranged from 1086 (Turquoise module) to 45 (Salmon). Eight coexpression modules were found to be significantly correlated (P < 0.05) with two clinic traits, namely disease status, and severity. Four modules were positively correlated ( P < 0.05) with the traits and these, therefore, contained genes that are mostly overexpressed in asthma. Contrastingly, the four other modules were found to be negatively correlated with the clinic traits. Functional enrichment analysis of the positively correlated modules showed that one (Magenta) was mainly enriched in mast cell activation and degranulation; another (Pink) was largely involved in immune cell response; the third (Yellow) was predominantly enriched in transmembrane signal pathways; and the last (Blue) was mainly enriched in substructure components of the cells. The hub genes in the modules were KIT, KITLG, GATA2, CD44, PTPRC, and CFTR, and these were confirmed as having significantly higher expression in the nasal epithelial cells. Combining the six hub genes enabled a relatively high capacity for discrimination between asthmatics and healthy subjects with an area under the receiver operating characteristic (ROC) curve of 0.924.

CONCLUSIONS

Our findings provide a framework of coexpression gene modules from nasal epithelial brushing samples that could be used for the prognostic study of allergic asthma.