Respiratory review of 2014: asthma

Selaginella uncinata flavonoids ameliorated ovalbumin-induced airway inflammation in a rat model of asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Selaginella uncinata (Desv.) Spring, known as "Cuiyuncao", is a perennial herb widely distributed in the Southeast Asian countries. In the folk medicine, the local minority commonly use it to treat cough and asthma for centuries.

AIM OF THE STUDY

This study was carried out to investigate the protective mechanisms of total flavonoids from S. uncinata (SUF) on airway hyperresponsiveness, cytokine release and bitter taste receptors (T2Rs) signaling with emphasis on inflammatory responses in a rat model of ovalbumin (OVA)-induced asthma.

MATERIALS AND METHODS

Rats were sensitized and challenged with OVA to induce typical asthmatic reactions. Pathological changes of lung tissue were examined by HE staining. The serum levels of T cell-associated cytokines (IFN-γ, IL-4, IL-5 and IL-13), total IgE and OVA-specific IgE were determined by enzyme-linked immunosorbent assay (ELISA). Gene expressions of T2R10, IP3R1 and Orai1 in lung tissue were assayed by fluorescence quantitative real-time polymerase chain reaction (FQ-PCR) while protein expressions of NFAT1 and c-Myc were assayed by western blot analysis. The activation of SUF was investigated on tansgentic T2R10-GFP HEK293 cells.

RESULTS

SUF treatment attenuated airway hyperresponsiveness and goblet cell hyperplasia compared with OVA-challenged asthmatic rats. The serum levels of IL-4, IL-5 and IL-13 as well as total and OVA-specific IgE were decreased while serum IFN-γ was increased in SUF-treated rats. SUF treatment significantly up-regulated T2R10 gene expression, down-regulated IP3R1 and Orai1 gene expression. SUF further suppressed eotaxin, NFAT1 and c-Myc protein expression in lung tissues of OVA-challenged rats.

CONCLUSIONS

These results imply that SUF exerts anti-inflammatory function through the T2R10/IP3R1/NFAT1 dependent signaling pathway, and may warrant further evaluation as a possible agent for the treatment of asthma.

Asthma-COPD Overlap Shows Favorable Clinical Outcomes Compared to Pure COPD in a Korean COPD Cohort

Purpose

Comparisons of the characteristics of chronic obstructive pulmonary disease (COPD) and asthma-COPD overlap syndrome (ACOS) have been the focus of several studies since the diseases were defined by the Global Initiative for Asthma and Global Initiative for Chronic Obstructive Lung Disease guidelines. However, no consensus is available yet. In this study, we aimed to compare the characteristics of asthma-COPD overlap (ACO) and COPD.

Methods

We retrospectively reviewed 1,504 patients with COPD in a Korean COPD Subtype Study cohort. The occurrence of ACO was defined as a positive response to a bronchodilator (an increase in forced expiratory volume in 1 second [FEV1] of 12% and 200 mL).

Results

Among 1,504 patients with COPD, 223 (14.8%) were diagnosed with ACO. Men (95.5%) and current smokers (32.9%) were more prevalent in the ACO group compared with the pure COPD group (90.5% and 25.3%, respectively; P=0.015 and P=0.026, respectively). Patients with ACO had a better quality of life (St. George's Respiratory Questionnaire for COPD score=31.0±18.0 [mean±standard deviation]) than those with pure COPD (35.3±19.1) (P=0.002). Although the prevalence of acute exacerbation was not different between the 2 groups, patients with severe exacerbation required hospital admission significantly more frequently in the pure COPD group than in the ACO group. Patients with ACO showed a higher likelihood of FEV1 recovery than those with pure COPD (P<0.001).

Conclusions

We suggest that ACO is characterized by less severe symptoms, and therefore it might lead to rare severe exacerbation and the possibility of lung function recovery.

Investigation of the Possible Role of the Hippo/YAP1 Pathway in Asthma and Allergy

Purpose

Several lines of evidence indicate that the Hippo/Yes-associated protein 1 (YAP1) pathways might play a role in the pathogenesis of asthma. To investigate the possible role of the Hippo/YAP1 pathway in the pathogenesis of asthma or its phenotypes.

Methods

The levels of gene expressions of the members of the Hippo/YAP1 were compared. The presence of the proteins of the YAP1 and FRMD6 were analyzed with Western blot in induced sputum of 18 asthmatic subjects and 10 control subjects. Fourteen single nucleotide polymorphisms (SNPs) in the YAP1 gene were genotyped in 522 asthmatic subjects and 711 healthy controls. The results were evaluated with traditional frequentist methods and with Bayesian network-based Bayesian multilevel analysis of relevance (BN-BMLA).

Results

The mRNA of all the members of the Hippo/YAP1 pathway could be detected in the induced sputum of both controls and cases. A correlation was found between YAP1 mRNA levels and sputum bronchial epithelial cells (r=0.575, P=0.003). The signal for the FRMD6 protein could be detected in all sputum samples while the YAP1 protein could not be detected in the sputum samples, of the healthy controls and severe asthmatics, but it was detectable in mild asthmatics. The rs2846836 SNP of the YAP1 gene was significantly associated with exercise-induced asthma (odds ratio [OR]=2.1 [1.3-3.4]; P=0.004). The distribution of genotypes of rs11225138 and certain haplotypes of the YAP1 gene showed significant differences between different asthma severity statuses. With BN-BMLA, 2 SNPs, genetic variations in the FRMD6 gene proved to be the most relevant to exercise-induced asthma and allergic rhinitis. These 2 SNPs through allergic rhinitis and exercise-induced asthma were in epistatic interaction with each other.

Conclusions

Our results provided additional evidence that the FRMD6/Hippo/YAP1 pathway plays a role in the pathogenesis of asthma. If additional studies can confirm these findings, this pathway can be a potential novel therapeutic target in asthma and other inflammatory airway diseases.

Allergic Rhinitis in Preschool Children and the Clinical Utility of FeNO

PURPOSE

The nature of allergic rhinitis (AR) in preschool aged children remains incompletely characterized. This study aimed to investigate the prevalence of AR and its associated risk factors in preschool-aged children and to assess the clinical utility of fractional exhaled nitric oxide (FeNO).

METHODS

This general population-based, cross-sectional survey included 933 preschool-aged (3- to 7-year-old) children from Korea. Current AR was defined as having nasal symptoms within the last 12 months and physician-diagnosed AR.

RESULTS

The prevalence of current AR in preschool children was 17.0% (156/919). Mold exposure (adjusted odds ratio [aOR], 1.67; 95% confidence interval [CI], 1.15-2.43) and the use of antibiotics (aOR, 1.97; 95% CI, 1.33-2.90) during infancy were associated with an increased risk of current AR, whereas having an older sibling (aOR, 0.52; 95% CI, 0.35-0.75) reduced the risk. Children with current atopic AR had significantly higher geometric mean levels of FeNO compared to those with non-atopic rhinitis (12.43; range of 1standard deviation [SD], 7.31-21.14 vs 8.25; range of 1SD, 5.62-12.10, P=0.001) or non-atopic healthy children (8.58; range of 1SD, 5.51-13.38, P<0.001). The FeNO levels were higher in children with current atopic AR compared with atopic healthy children (9.78; range of 1SD, 5.97-16.02, P=0.083).

CONCLUSIONS

Mold exposure and use of antibiotics during infancy increases the risk of current AR, whereas having an older sibling reduces it. Children with current atopic AR exhibit higher levels of FeNO compared with non-atopic rhinitis cases, suggesting that FeNO levels may be a useful discriminatory marker for subtypes of AR in preschool children.

Metabolic Functions of the Lung, Disorders and Associated Pathologies

The primary function of the lungs is gas exchange. Approximately 400 million years ago, the Earth's atmosphere gained enough oxygen in the gas phase for the animals that emerged from the sea to breathe air. The first lungs were merely primitive air sacs with a few vessels in the walls that served as accessory organs of gas exchange to supplement the gills. Eons later, as animals grew accustomed to a solely terrestrial life, the lungs became highly compartmentalized to provide the vast air-blood surface necessary for O2 uptake and CO2 elimination, and a respiratory control system was developed to regulate breathing in accordance with metabolic demands and other needs. With the evolution and phylogenetic development, lungs were taking a variety of other specialized functions to maintain homeostasis, which we will call the non-respiratory functions of the lung and that often, and by mistake, are believed to have little or no connection with the replacement gas. In this review, we focus on the metabolic functions of the lung, perhaps the least known, and mainly, in the lipid metabolism and blood-adult lung vascular endothelium interaction. When these functions are altered, respiratory disorders or diseases appear, which are discussed concisely, emphasizing how they impact the most important function of the lungs: external respiration.