Hiroshi Koto

Eosinophilic airway inflammation induced by repeated exposure to cigarette smoke

Acute exposure to cigarette smoke causes airway hyperresponsiveness (AHR) in guinea-pigs, which resolves within a few hours. Repeated exposure may have a different effect on the airways. To address this question, guinea-pigs were repeatedly exposed to cigarette smoke (six cigarettes for 1 h x day(-1)) for 14 consecutive days. Airway responsiveness to inhaled histamine and differential cell counts in bronchoalveolar lavage fluid (BALF) were evaluated 1 day after the last exposure. Significant neutrophilia in BALF was observed after 3 days of smoke exposure. Significant eosinophilia in BALF and AHR were observed after 14 days of smoke exposure, but not after 3 or 7 days of smoke exposure. These changes persisted until 3 days after the last exposure and resolved 7 days afterwards. Histologically, the recruited eosinophils were observed predominantly in the airways, but not in the alveoli. Treatment with E-6123, a specific platelet-activating factor receptor antagonist (1 mg x kg(-1) x day(-1) p.o. during smoke exposure) significantly inhibited the eosinophil influx and AHR. Repeated exposure to cigarette smoke may induce prolonged airway inflammation and airway hyperresponsiveness in guinea-pigs. Platelet-activating factor or platelet-activating factor-like lipids may play a key role in airway hyperresponsiveness, presumably by the induction of eosinophilic airway inflammation.

Effect of inhaled glucocorticoid on the cellular profile and cytokine levels in induced sputum from asthmatic patients

Abstract. Cytokines are considered to play a role in the airway inflammation of bronchial asthma. We examined the cellular profile and cytokine levels in induced sputum samples obtained before and after treatment with beclomethasone dipropionate (BDP, 800 μg/day, for 4 weeks) in 12 mild to moderate asthmatic subjects who had not previously received inhaled glucocorticosteroids. Sputum was induced with a 20-min inhalation of 3% saline by an ultrasonic nebulizer. The freshly expectorated sputum separated from the saliva was analyzed for cell counts, for the concentration of interleukin-8 (IL-8), and for the concentration of granulocyte-macrophage colony-stimulating factor (GM-CSF). The mean percentage of eosinophils in the sputum samples decreased significantly after BDP treatment, but no significant change in the percentage of neutrophils was observed. The mean IL-8 and GM-CSF levels also decreased significantly after treatment. The BDP treatment was associated with an increase in the mean peak expiratory flow (PEF) and with a decrease in the diurnal variation of PEF. These results suggest that inhaled steroids improve airway inflammation and lung function in asthmatics, presumably in part by inhibiting the synthesis of inflammatory cytokines such as IL-8 and GM-CSF.

Role of neutrophil elastase in ozone-induced airway responses in guinea-pigs

Ozone-induced airway hyperresponsiveness occurs concurrently with neutrophilic inflammation and epithelial injury in various species including humans. The mechanism of neutrophil-induced airway hyperresponsiveness, however, has not yet been fully clarified. Neutrophil elastase (NE) is a multipotent protease released from activated neutrophils, which may play a role in ozone-induced airway hyperresponsiveness. In order to address this issue, the effects of ONO-5046, a specific NE inhibitor, were investigated in ozone-exposed guinea-pigs. Awake animals were exposed to ozone at 3 parts per million for 2 h, airway responsiveness to acetylcholine (ACh) measured and examination of bronchoalveolar lavage fluid (BALF) performed. Ozone exposure increased airway responsiveness to both inhaled and intravenous ACh, the concentration of NE in BALF and the number of neutrophils and airway epithelial cells in BALF. Although pretreatment with ONO-5046 (200 mg x kg(-1), i.p.) had no effect on these changes immediately after the exposure, it significantly inhibited airway hyperresponsiveness to inhaled ACh, whilst decreasing the number of neutrophils and epithelial cells in BALF 3-5 h after the exposure. In contrast, ONO-5046 showed no significant effect on airway hyperresponsiveness to intravenous ACh at any time. These results suggest that neutrophil elastase contributes to ozone-induced airway hyperresponsiveness developing during the hours after exposure, presumably by means of inducing epithelial injury.

Effect of suplatast tosilate on airway hyperresponsiveness and inflammation in asthma patients

Because eosinophilic airway inflammation is a characteristic of bronchial asthma, the treatment of such inflammation is important in the management of this disease. Suplatast tosilate is a novel anti-asthma drug that suppresses eosinophil proliferation and infiltration through selective inhibition of Th2 cytokine synthesis. We investigated the effect of oral suplatast tosilate therapy in patients with mild and moderate asthma. Twenty-eight asthma patients were randomized into two groups with or without suplatast tosilate treatment (100 mg t.i.d. for 28 days). We examined the blood eosinophil counts, eosinophilic cationic protein level, sputum eosinophil count, exhaled nitric oxide level, and airway responsiveness before and after treatment. In patients treated with suplatast tosilate, the eosinophil count in the blood and sputum was significantly decreased after treatment, while there was no such change in the patients without suplatast treatment. The exhaled nitric oxide level and airway responsiveness (measured using an Astograph) were also decreased after treatment with suplatast tosilate, while there were no significant changes in patients without suplatast tosilate. These results strongly suggest that oral administration of suplatast tosilate suppresses airway hyperresponsiveness in asthma patients by reducing eosinophilic inflammation in the airways.

Effects of thromboxane A2 antagonist on airway hyperresponsiveness, exhaled nitric oxide, and induced sputum eosinophils in asthmatics

We examined effects of a thromboxane A2 (TXA2) antagonist seratrodast on airway hyperresponsiveness, exhaled nitric oxide (NO), and eosinophils in induced sputum in 14 asthmatics. Subjects were administered 80 mg of seratrodast once a day for 4 weeks. Respiratory conductance (Grs) was measured by the forced oscillation method and airway responsiveness was evaluated as the inhaled dose of methacholine, which induced 35% decrease in Grs. Subjects breathed into a Teflon bag, and NO concentration in the bag was measured by a chemiluminescence analyzer. Induced sputum comprised the entire expectorate produced during a 20 min inhalation of 3% saline, and was analyzed for total and differential cell counts. Airway hyperresponsiveness was significantly decreased by seratrodast. By contrast, no differences in either exhaled NO or percentage of eosinophils in sputum were observed before or after seratrodast. We conclude that seratrodast may attenuate airway hyperresponsiveness, presumably by antagonizing TXA2 released from the inflamed airways.

Neutrophil elastase inhibitor, ONO-5046 suppresses ozone-induced airway mucus hypersecretion in guinea pigs

To investigate the role of neutrophil elastase in ozone-induced airway hypersecretion, we measured goblet cell secretion by using a semiquantitative morphometric technique in guinea pigs. The magnitude of mucus discharge was estimated from the mucus score, which is inversely related to the degree of mucus discharge in histological sections of trachea stained for mucus glycoprotein with periodic acid Schiff/Alcian blue. Mucus hypersecretion of goblet cells was induced by ozone exposure and persisted for up to 5 h after exposure. Pretreatment with N-[2-¿4-(2,2-dimethyl-propionyloxy) phenyl-sulfonylamino¿ benzoyl] aminoacetic acid (ONO-5046), a specific neutrophil elastase inhibitor (200 mg/kg, intraperitoneally), significantly inhibited goblet cell hypersecretion both just after and 5 h after ozone-exposure, but the latter inhibition was not complete. In bronchoalveolar lavage fluid, ozone exposure significantly increased the number of neutrophils just after and 5 h after exposure, while ONO-5046 significantly inhibited the increase in neutrophils only 5 h after ozone-exposure. These results indicate that neutrophil elastase may play an important role in the ozone-induced tracheal goblet cell hypersecretion and influx of neutrophils.

Ipratropium bromide protects against bronchoconstriction during bronchoscopy

Pulmonary function is reportedly impaired by fiberoptic bronchoscopy. We investigated the effect of two anticholinergic agents, intramuscular atropine and inhaled ipratropium bromide, on bronchoconstriction in 29 patients who were undergoing diagnostic bronchoscopy. The patients were divided into three groups; the first received 0.5 mg of atropine intramuscularly; the second took four puffs of 0.02 mg ipratropium bromide aerosolized by a metered-dose inhaler, and the third inhaled four puffs of a placebo. Fifteen minutes later a standardized topical anesthetic, lidocaine, was administered, and a bronchoscopic examination was performed. Pulmonary function was measured before and 15 minutes after each step. Pulmonary function was not affected by the treatment with anticholinergics or the placebo. In the placebo and the atropine groups, the topical anesthesia produced significant reductions in forced expiratory volume in 1 second (FEV,) and peak expiratory flow rate (PEFR); further reductions in these values were observed after bronchoscopy. In the group treated with ipratropium bromide there were no significant changes in FEV, and PEFR after topical anesthesia. Bronchoscopy induced significant reductions in FEV1 and PEFR, but the changes were significantly smaller than those seen in the placebo and atropine groups. The results suggest that the deleterious effect of bronchoscopy on pulmonary function is due to topical lidocaine anesthesia and to the bronchoscopic examination itself. Inhaled ipratropium bromide protects against these deleterious effects, whereas intramuscular atropine does not.

Thromboxane A2 antagonist inhibits leukotriene D4-induced smooth muscle contraction in guinea-pig lung parenchyma, but not in trachea

Although the bronchoconstriction induced by leukotriene D4 (LTD4) has been reported to be partly mediated by thromboxane A2 (TXA2) in the guinea-pig airway, it is not known which part of the airway is susceptible to TXA2. In order to determine the role of TXA2 in the central and peripheral airways, we compared the effect of a TXA2 antagonist on tracheal strips to its effect on parenchymal strips of guinea-pigs. Tracheal and parenchymal strips were mounted in a 3.5 ml organ bath filled with Krebs-Henseleit solution aerated with 95% O2, 5% CO2 and kept at 37 degrees C. After equilibration for 60 min in Krebs solution, the strip was contracted by exposure to 10(-5) M of acetylcholine (ACh). Sixty minutes after ACh was eliminated, the concentration-response curve to LTD4 (10(-9) M-10(-7) M) was obtained, and the LTD4-induced contractions were expressed as the percent of the contraction evoked by 10(-5) M of ACh. We measured the contractile response to LTD4 in the presence or absence of the TXA2 antagonist, BAY u3405 (10(-8) M-10(-6) M). In the tracheal strips, BAY u3405 had no effect on the LTD4-induced contraction. However, in parenchymal strips, BAY u3405 significantly suppressed the contractile response to LTD4. These results suggest that in the central airway LTD4 contracts smooth muscle directly, but that in the peripheral airway LTD4 induces smooth muscle contraction both directly and indirectly, via TXA2.

Effect of BAY u3405, a thromboxane A2 receptor antagonist, on neuro-effector transmission in canine tracheal tissue

Thromboxane A2 (TXA2) is reported to potentiate vagal nerve neuro-effector transmission in airway smooth muscle tissue. We investigated the effects of BAY u3405 (3(R)-[[4-fluorophenyl)sulfonyl]amino]-1,2,3,4,-tetrahydro-9H-carbazole - 9-propanoic acid), a potent and selective TXA2 receptor antagonist, on the increase in vagal nerve neuro-effector transmission induced by a TXA2 mimetic, U-46619, in the canine trachea. We measured the contractions of canine tracheal smooth muscle evoked by electrical field stimulation (EFS) and by acetylcholine (ACh) in the presence and absence of a subthreshold dose of U-46619 (the highest dose that did not induce any smooth muscle contraction). We then examined whether BAY u3405 inhibited the effect of U-46619 on tracheal smooth muscle. The following results were obtained: (i) subthreshold doses of U-46619 (10(-10) M and 10(-9) M) significantly increased the amplitude of the contractions evoked by EFS; (ii) by contrast, U-46619 had no effect on the contractile response of smooth muscle to exogenously applied ACh; (iii) the contraction evoked by EFS was completely abolished by the application of atropine (10(-6) M) or tetrodotoxin (10(-7) M), indicating that EFS caused the smooth muscle contraction through the release of ACh from vagal nerve terminals; and (iv) pretreatment with BAY u3405 (10(-6) M) abolished the excitatory action of U-46619 on the amplitude of twitch contraction evoked by EFS in the trachea. These results indicate that U-46619, at low concentrations, has a prejunctional action stimulating neuro-effector transmission, presumably increasing ACh release from vagal nerve terminals through TXA2 receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence of asthma with airflow limitation, COPD, and COPD with variable airflow limitation in older subjects in a general Japanese population: The Hisayama Study

BACKGROUND Elucidating the prevalence of asthma and chronic obstructive pulmonary disease (COPD) is important for designing a public health strategy. Recent studies have discriminated a phenotype of COPD with variable airflow limitation (COPD-VAL) associated with asthma-COPD overlap syndrome. Its prevalence remains uncertain. The age and occupational distributions in the town of Hisayama and in Japan are nearly identical. Each diseases prevalence was estimated for the towns residents. METHODS In 2008, town residents (≥ 40 years) were solicited to participate in a health checkup. Individuals with abnormal spirometry (forced expiratory volume in 1s/forced vital capacity [FEV1/FVC]<70% and/or %FVC<80%) were recommended for further evaluations. Two pulmonologists in a blinded fashion reviewed their medical records, including bronchodilator reversibility. Individuals with airflow limitation were classified as having asthma, COPD, COPD-VAL, or other diseases. The prevalence of each disease was then estimated. RESULTS A total of 2100 residents (43.4% of residents in the age group) completed spirometry. In 455 residents with abnormal spirometry, 190 residents had further evaluations, and the medical records of 174 residents were reviewed. The prevalence of asthma with airflow limitation, COPD, and COPD-VAL, were 2.0%, 8.4%, and 0.9%, respectively. The prevalence of COPD and COPD-VAL were higher in men and smokers than in women and never-smokers. The prevalence of COPD, but not COPD-VAL or asthma, increased with age. CONCLUSION The prevalence of asthma with airflow limitation, COPD, and COPD-VAL were estimated in a population of residents (≥ 40 years) in Hisayama.