Hisako Matsumoto

Genome-wide association study identifies three new susceptibility loci for adult asthma in the Japanese population

Bronchial asthma is a common inflammatory disease caused by the interaction of genetic and environmental factors. Through a genome-wide association study and a replication study consisting of a total of 7,171 individuals with adult asthma (cases) and 27,912 controls in the Japanese population, we identified five loci associated with susceptibility to adult asthma. In addition to the major histocompatibility complex and TSLP-WDR36 loci previously reported, we identified three additional loci: a USP38-GAB1 locus on chromosome 4q31 (combined P = 1.87 × 10−12), a locus on chromosome 10p14 (P = 1.79 × 10−15) and a gene-rich region on chromosome 12q13 (P = 2.33 × 10−13). We observed the most significant association with adult asthma at rs404860 in the major histocompatiblity complex region (P = 4.07 × 10−23), which is close to rs2070600, a SNP previously reported for association with FEV1/FVC in genome-wide association studies for lung function. Our findings offer a better understanding of the genetic contribution to asthma susceptibility.

High sensitivity C-reactive protein in asthma

Asthma is characterised by chronic inflammation of the airways, but the relevance of high-sensitivity assays for C-reactive protein (hs-CRP), which are known to be a sensitive marker of low-grade systemic inflammation, has not been fully studied in asthma. The objective was to examine serum hs-CRP levels in patients with asthma and their relationship to clinical characteristics and degree of airway inflammation. Serum hs-CRP levels were cross-sectionally examined in steroid-naive (n = 22) and steroid-inhaling (n = 23) adult patients with asthma and healthy controls (n = 14). All were nonsmokers. Serum hs-CRP levels were significantly increased in steroid-naive patients (mean±sd 1.33±1.48 mg·L−1) compared with controls (0.21±0.30 mg·L−1), but not in patients on inhaled corticosteroid. Among steroid-naive patients, serum hs-CRP levels significantly negatively correlated with indices of pulmonary function (forced expiratory volume in one second/forced vital capacity and forced mid-expiratory flow) and positively with sputum eosinophil count. Among patients on inhaled corticosteroid, hs-CRP levels did not correlate with any indices. In conclusion, an increase in serum C-reactive protein levels measured by high-sensitivity assays may be associated with airflow obstruction and airway inflammation, and may serve as a surrogate marker of airway inflammation in asthma.

Increased periostin associates with greater airflow limitation in patients receiving inhaled corticosteroids.

BACKGROUND Periostin, an extracellular matrix protein, contributes to subepithelial thickening in asthmatic airways, and its serum levels reflect airway eosinophilic inflammation. However, the relationship between periostin and the development of airflow limitation, a functional consequence of airway remodeling, remains unknown. OBJECTIVE We aimed to determine the relationship between serum periostin levels and pulmonary function decline in asthmatic patients on inhaled corticosteroid (ICS) treatment. METHODS Two hundred twenty-four asthmatic patients (average age, 62.3 years) treated with ICS for at least 4 years were enrolled. Annual changes in FEV1, from at least 1 year after the initiation of ICS treatment to the time of enrollment or later (average, 16.2 measurements over 8 years per individual), were assessed. At enrollment, clinical indices, biomarkers that included serum periostin, and periostin gene polymorphisms were examined. Associations between clinical indices or biomarkers and a decline in FEV1 of 30 mL or greater per year were analyzed. RESULTS High serum periostin levels (≥ 95 ng/mL) at enrollment, the highest treatment step, higher ICS daily doses, a history of admission due to asthma exacerbation, comorbid or a history of sinusitis, and ex-smoking were associated with a decline in FEV1 of 30 mL or greater per year. Multivariate analysis showed that high serum periostin, the highest treatment step, and ex-smoking were independent risk factors for the decline. Polymorphisms of periostin gene were related to higher serum periostin levels (rs3829365) and a decline in FEV1 of 30 mL or greater per year (rs9603226). CONCLUSIONS Serum periostin appears to be a useful biomarker for the development of airflow limitation in asthmatic patients on ICS.

Effects of obstructive sleep apnea syndrome on serum aminotransferase levels in obese patients

PURPOSE Obesity has been associated with obstructive sleep apnea and hepatic steatosis. We investigated the effects of obstructive sleep apnea and treatment with nasal continuous positive airway pressure (CPAP) on serum aminotransferase levels in obese patients. METHODS We studied 40 obese men with obstructive sleep apnea syndrome. None had hepatitis B antigen or C antibody, autoimmune disease, or an excessive intake of alcohol. Serum levels of aspartate aminotransferase, alanine aminotransferase, triglyceride, glucose, insulin, and leptin were determined in the afternoon and in the morning immediately after sleep, before and after nasal CPAP treatment. RESULTS Aminotransferase levels were abnormal in 35% (n = 14) of patients. Before treatment, mean (+/- SD) aspartate aminotransferase levels were higher in the morning than in the previous afternoon (presleep, 34 +/- 20 IU/L; postsleep, 39 +/- 28 IU/L; P = 0.006). The overnight mean increases in aminotransferase levels were less marked after the first night of nasal CPAP treatment (aspartate aminotransferase: from 6 +/- 11 IU/L to 2 +/- 6 IU/L, P = 0.0003; alanine aminotransferase: from 5 +/- 9 IU/L to 2 +/- 6 IU/L, P = 0.006). Leptin levels (n = 23) decreased significantly after treatment (P = 0.0002), whereas insulin resistance (calculated by the homeostasis model assessment method) and triglyceride levels were unchanged. Improvements in aspartate and alanine aminotransferase levels were maintained after 1 and 6 months of nasal CPAP treatment. CONCLUSION Nasal CPAP therapy may have beneficial effects on serum aminotransferase abnormalities in obese patients who have obstructive sleep apnea.

Airway remodelling in cough-variant asthma.

Subepithelial-layer thickening, a pathological feature of airway remodelling, is present in cough-variant asthma. In bronchial biopsy samples we found mean subepithelial-layer thickness was 7.1 (SE 0.4) microm in patients with cough-variant asthma, 8.6 (0.4) microm in patients with classic asthma with wheezing, and 5.0 (0.2) microm in healthy controls. Thickness was significantly higher in patients with asthma than in controls, and was significantly greater in those with classic asthma than in those with cough-variant asthma. Early anti-inflammatory treatment might, therefore, be beneficial in cough-variant asthma, as recommended in classic asthma.

Relationship of airway wall thickening to an imbalance between matrix metalloproteinase-9 and its inhibitor in asthma

Background: The balance between matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) may be critical in extracellular matrix remodelling, a characteristic of asthmatic airways. An excess of TIMP-1 over MMP-9 has been associated with chronic airflow obstruction but the mechanisms underlying this association remain unknown. Recent computed tomographic (CT) studies indicate that airway wall thickening is associated with chronic airflow obstruction. Methods: Sputum levels of MMP-9, TIMP-1, and their molar ratio were examined in 26 patients with stable asthma and their relationship with pulmonary function and airway wall thickness, assessed by a validated CT technique which measured wall area corrected by body surface area (WA/BSA), the ratio of WA to outer wall area (WA%), and the absolute wall thickness corrected by √BSA of a segmental bronchus (T/√BSA), was examined. Results: Sputum MMP-9 levels were inversely correlated with WA% and TIMP-1 levels were positively correlated with WA/BSA and T/√BSA. The MMP-9/TIMP-1 molar ratio was inversely correlated with WA% and T/√BSA and positively correlated with post-bronchodilator values of mid-forced expiratory flow and maximum expiratory flow at the quartile of lung volume. Conclusion: Excess TIMP-1 may have a pathogenetic role in airway wall thickening in asthmatic patients which may result in chronic airflow obstruction.

Relationship between small airway function and health status, dyspnea and disease control in asthma.

Background: Small airways play important roles in the pathophysiology of asthma. However, relationships between small airway involvement and health status and dyspnea have not been investigated. Objectives: It was the aim of this study to assess the relationships between proximal and peripheral airway functions and health status, dyspnea and disease control in patients with asthma, using impulse oscillometry (IOS). Methods: We performed IOS, spirometry and assessment of health status (Asthma Quality of Life Questionnaire and St. George’s Respiratory Questionnaire), dyspnea (Baseline Dyspnea Index) and disease control (Asthma Control Questionnaire) in 65 asthmatics and evaluated their relationships. Results: Peripheral airway function as evaluated by IOS [R5–R20 (the fall in resistance from 5 to 20 Hz) and X5 (reactance at 5 Hz)], in addition to the proximal airway index (R20), significantly correlated with health status, dyspnea and disease control. Multiple regression analyses revealed that peripheral airway function significantly contributes to these, independently of the proximal airway index. In contrast, forced expiratory volume in 1 s did not significantly contribute to health status or dyspnea. Conclusions: IOS correlated better with clinical symptoms and asthma control than spirometry in patients with asthma. Peripheral and proximal airway functions as assessed separately by IOS independently contribute to health status, dyspnea and disease control, indicating that peripheral airways also represent an important therapeutic target.

Effect of oestrogen on Mycobacterium avium complex pulmonary infection in mice

The purpose of the present study was to elucidate the role of oestrogen in the pathogenesis of Mycobacterium avium complex (MAC) pulmonary disease, which occurs most frequently in postmenopausal women. The study was carried out in a murine infectious model using ovariectomized DBA/2 female mice. Infection with MAC was established by intratracheal administration of bacilli. In some experiments, ovariectomized mice were treated with exogenous 17β‐estradiol (E2). The number of bacilli in the lungs of infected mice which received ovariectomy was significantly larger than that in the lungs of sham‐operated control mice, and treatment of ovariectomized mice with exogenous E2 restored the burden of bacilli to the same level as that in the sham‐operated control mice. We next examined the effect of E2 in vitro using bone marrow‐derived macrophages obtained from DBA/2 female mice. The macrophages showed bacteriostatic activity against MAC after treatment with interferon‐gamma (IFN‐γ) and this activity was further enhanced by the exogenous addition of E2 to the culture medium. In parallel with these findings, E2 augmented the production of reactive nitrogen intermediates (RNI) by macrophages pretreated with IFN‐γ and stimulated with MAC, as shown by evaluating nitrite production and inducible nitric oxide synthase mRNA expression. These findings taken together suggest that absence of endogenous oestrogen appears to be responsible for the development of MAC pulmonary disease in this mouse model and that the enhancement by E2 of anti‐MAC activity of murine macrophages induced through increased RNI production may play some role in resistance to MAC infection.

Roles of Periostin in Respiratory Disorders

Periostin is a matricellular protein that has been implicated in many disease states. It interacts with multiple signaling cascades to modulate the expression of downstream genes that regulate cellular interactions within the extracellular matrix. This review focuses on the role of periostin in respiratory diseases, including asthma and idiopathic pulmonary fibrosis, and its potential to help guide treatment or assess prognosis. Epithelial injury is a common feature of many respiratory diseases, resulting in the secretion, among others, of periostin, which is subsequently involved in airway remodeling and other aspects of pulmonary pathophysiology. In asthma, periostin is recognized as a biomarker of type 2 inflammation; POSTN gene expression is up-regulated in bronchial epithelial cells by IL-13 and IL-4. Serum periostin has been evaluated for the identification of patients with increased clinical benefit from treatment with anti-IL-13 (lebrikizumab, tralokinumab) and anti-IgE (omalizumab) therapy and may be prognostic for increased risk of asthma exacerbations and progressive lung function decline. Furthermore, in asthma, periostin may regulate subepithelial fibrosis and mucus production and may serve as a systemic biomarker of eosinophilic airway inflammation. Periostin is also highly expressed in the lungs of patients with idiopathic pulmonary fibrosis, and its serum levels may predict clinical progression. Overall, periostin contributes to multiple pathogenic processes across respiratory diseases, and peripheral blood levels of periostin may have utility as a biomarker of treatment response and disease progression.

Plasma thioredoxin, a novel oxidative stress marker, in patients with obstructive sleep apnea before and after nasal continuous positive airway pressure.

Obstructive sleep apnea (OSA) is associated with increased cardiovascular mortality, and oxidative stress was suggested to play an important role. We hypothesized that the plasma TRX level, a novel oxidative stress marker, is elevated in OSA patients. Plasma TRX and adiponectin levels, which are significantly associated with cardiovascular mortality, were measured in 41 patients with severe OSA before (n = 41) and after (n = 27) nasal continuous positive airway pressure therapy (nCPAP) for 1 month and in 12 subjects without OSA (non-OSA group). The TRX level was significantly higher (p = 0.02) and the adiponectin level was significantly lower (p = 0.02) in the OSA group than in the non-OSA group. After 1 month of nCPAP (n = 27), the TRX level significantly decreased (p = 0.03), and the adiponectin level significantly increased (p = 0.03). Among the 14 patients with untreated OSA, the TRX and adiponectin levels did not significantly change over a 1-month interval. Among the 53 (41 OSA + 12 non-OSA) subjects, the TRX level was positively correlated with the respiratory disturbance index (p = 0.001) and percentage of time with SaO(2) <90% (p = 0.0002). The adiponectin level, but not the TRX level, was correlated with the BMI (n = 53; p = 0.02). Plasma TRX may be a unique marker for evaluating oxidative stress and monitoring the effectiveness of nCPAP in OSA patients.