Teruaki Nishiuma

Inhalation of sphingosine kinase inhibitor attenuates airway inflammation in asthmatic mouse model

Sphingosine 1-phosphate (S1P) produced by sphingosine kinase (SPHK) is implicated in acute immunoresponses, however, mechanisms of SPHK/S1P signaling in the pathogenesis of bronchial asthma are poorly understood. In this study, we hypothesized that SPHK inhibition could ameliorate lung inflammation in ovalbumin (OVA)-challenged mouse lungs. Six- to eight-week-old C57BL/6J mice were sensitized and exposed to OVA for 3 consecutive days. Twenty-four hours later, mice lungs and bronchoalveolar lavage (BAL) fluid were analyzed. For an inhibitory effect, either of the two different SPHK inhibitors, N,N-dimethylsphingosine (DMS) or SPHK inhibitor [SK-I; 2-(p-hydroxyanilino)-4-(p-chlorophenyl) thiazole], was nebulized for 30 min before OVA inhalation. OVA inhalation caused S1P release into BAL fluid and high expression of SPHK1 around bronchial epithelial walls and inflammatory areas. DMS or SK-I inhalation resulted in a decrease in S1P amounts in BAL fluid to basal levels, accompanied by decreased eosinophil infiltration and peroxidase activity. The extent of inhibition caused by DMS inhalation was higher than that caused by SK-I. Like T helper 2 (Th2) cytokine release, OVA inhalation-induced increase in eotaxin expression was significantly suppressed by DMS pretreatment both at protein level in BAL fluid and at mRNA level in lung homogenates. Moreover, bronchial hyperresponsiveness to inhaled methacholine and goblet cell hyperplasia were improved by SPHK inhibitors. These data suggest that the inhibition of SPHK affected acute eosinophilic inflammation induced in antigen-challenged mouse model and that targeting SPHK may provide a novel therapeutic tool to treat bronchial asthma.

Inhalation of urokinase-type plasminogen activator reduces airway remodeling in a murine asthma model

The airway remodeling that occurs in asthma is characterized by an excess of extracellular matrix deposition in the submucosa, hyperplasia/hypertrophy of smooth muscle, goblet cell metaplasia, and accumulation of fibroblasts/myofibroblasts. The urokinase-type plasminogen activator (uPA)/plasmin system participates in pericellular proteolysis and is capable of directly degrading matrix components, activating latent proteinases, and activating growth factors. In a mouse ovalbumin (OVA) asthma model, we increased plasminogen activator activity in the lung by administering exogenous uPA or by using mice genetically deficient in the uPA inhibitor plasminogen activator inhibitor-1 (PAI-1) to assess the role of this system in asthma pathogenesis. After intraperitoneal OVA sensitization, mice inhaled OVA plus uPA (500 IU/mouse) or saline by ultrasonic nebulization for 3 wk. When studied 24 h after the final exposure, the groups with upregulated plasmin activity had significantly reduced subepithelial fibrosis within the airway walls and had decreased airway hyperresponsiveness (AHR) to methacholine. Morphometric analysis showed that subepithelial wall thickening of the bronchi (subepithelial area ratio) was also reduced, as were collagen and alpha-smooth muscle actin. Upregulation of plasmin activity also increased the level of hepatocyte growth factor activity in bronchoalveolar lavage fluid, whereas the release of transforming growth factor-beta was decreased. The administration of uPA 1 wk after the last OVA inhalation also significantly reduced lung hydroxyproline content and AHR. These results show that enhancing uPA/plasmin activity lessens the airway remodeling in a murine asthma model.

Overexpression of nitric oxide synthase by the endothelium attenuates bleomycin‐induced lung fibrosis and impairs MMP‐9/TIMP‐1 balance

Background:  Nitric oxide (NO) produced by endothelial NO synthase (eNOS) is thought to effect an anti‐inflammatory response, but its mechanism is still unknown.

Tumor necrosis factor-α augments contraction and cytosolic Ca2+ sensitivity through phospholipase A2 in bovine tracheal smooth muscle

Abstract To elucidate the effects of tumor necrosis factor-α (TNF-α) on tracheal smooth muscle contraction, we simultaneously measured isometric tension and intracellular Ca 2+ ([Ca 2+ ] i ) in fura 2-loaded muscle strips. Smooth muscle force generation was evaluated in a high potassium (K + ; 20.0–80.0 mM) solution and with acetylcholine (3 nM–10 μM ). TNF-α (1–100 ng/ml) did not directly contract muscle strips. The contractile response to acetylcholine was enhanced after application of 10 ng/ml of TNF-α for 30 min but not the response of [Ca 2+ ] i . The contractile response and the response of [Ca 2+ ] i to a high K + solution were not altered after application of TNF-α. The [Ca 2+ ] i –tension curve indicated that TNF-α enhanced the responsiveness of tracheal smooth muscle through the acetylcholine-mediated Ca 2+ sensitivity of intracellular contractile elements. The augmentation of the acetylcholine concentration–response curves for muscle tension in the presence of TNF-α (10 ng/ml) was inhibited in part after application of manoalide, a phospholipase A 2 inhibitor. We conclude that a low concentration of TNF-α enhances smooth muscle responsiveness to acetylcholine by agonist-mediated Ca 2+ sensitivity facilitated by phospholipase A 2 .

Sphingosine kinase 1 regulates mucin production via ERK phosphorylation.

Our previous report showed that inhibition of sphingosine kinase (SphK) ameliorates eosinophilic inflammation and mucin production in a mouse asthmatic model. To clarify the role of SphK in airway mucin production, we utilized the mouse asthmatic model and found that both SphK and MUC5AC expression were increased and co-localized in airway epithelium. Next we cultured normal human bronchial epithelial cells in an air-liquid interface and treated with IL-13 to induce their differentiation into goblet cells. We found that SphK1 and MUC5AC expression was increased by IL-13 treatment at both protein and mRNA levels, whereas SphK2 expression was not changed. N,N-dimethylsphingosine (DMS), a potent SphK inhibitor, decreased MUC5AC expression up-regulated by IL-13 treatment. Furthermore, DMS inhibited IL-13-induced ERK1/2 phosphorylation but neither p38 MAPK nor STAT6 phosphorylation. These results suggest that SphK1 is involved in MUC5AC production induced by IL-13 upstream of ERK1/2 phosphorylation, and independent of STAT6 phosphorylation.

Airway remodeling of murine chronic antigen exposure model.

Airway remodeling is one of the most important features of bronchial asthma. However, there are few studies that have used repeated antigen exposure in murine models. We designed a murine chronic antigen exposure model necessary for studying airway remodeling. Two different strains of mice, BALB/c mice and C57BL/6 mice, were sensitized and challenged for 3–7 weeks with ovalbumin (OVA). Bronchoalveolar lavage (BAL) and histology study were conducted in each phase. Morphometry was performed, and the epithelial area ratio (Ae ratio) and subepithelial area ratio (As ratio) were calculated. The Ae ratio and As ratio of BALB/c mice were significantly increased in sensitized mice compared with nonsensitized mice at 3 and 5 weeks, but not at 7 weeks. In C57BL/6 mice, the Ae ratio showed no significant changes, whereas the As ratio maintained high from 3 to 7 weeks. This thickening of the subepithelial layer consisted of collagen fibers with elastica van‐Gieson (EVG) stain. Lymphocytes of the BAL showed a significant increase at 3 and 7 weeks in C57BL/6 mice, but not in BALB/c mice. A murine chronic OVA exposure model in C57BL/6 mice revealed subepithelial layer thickening consisting of collagen fibers and increased lymphocytes until 7 weeks. C57BL/6 mice are useful to elucidate the mechanism of airway remodeling.

Characteristics of Patients with Chronic Cough Who Developed Classic Asthma during the Course of Cough Variant Asthma: A Longitudinal Study

Background: Some patients develop asthmatic symptoms such as wheezing and dyspnea during the course of cough variant asthma (CVA), which are considered precursors of classical asthma. Objectives: To identify the characteristics of such patients, we investigated the nature of CVA patients with or without developing bronchial asthma in the longitudinal study. Methods: In 28 CVA patients whom we could observe over 5 years, duration of coughing, physical examination findings, pulmonary function and bronchial hyperresponsiveness to inhaled methacholine were retrospectively assessed. Results: Of these patients with CVA, 10 developed the asthmatic symptoms of wheezing and dyspnea (precursors of classical asthma) over 5 years. All these 10 patients showed marked bronchial hyperresponsiveness; however, there were no significant differences in the bronchial responsiveness to methacholine between patients with precursors of classical asthma and pure CVA patients who did not wheeze. The duration of coughing had a significant relationship with precursors of classical asthma. Seven patients with precursors of classical asthma developed wheezing in the first year and 1 patient each in the second, third and fourth year. Conclusions: These findings of a 5-year observation suggest that longer duration of coughing may be an important factor that develops precursors of classical asthma in patients with CVA.

Usefulness of the Oximetry Test for the Diagnosis of Sleep Apnea Syndrome in Japan

We evaluated the usefulness of oximetry tests that are frequently used as screening tools for sleep apnea syndrome (SAS) by determining the level of agreement between oximetry test results and polysomnography test (PSG) results. We retrospectively examined 135 patients suspected of having SAS. Although the oximetry desaturation index (DSI) seemed better than the oximetry apnea index in the agreement with the polysomnography respiratory disturbance index (RDI), the criteria of DSI greater than or equal to 15 was not sensitive enough to screen for moderate SAS (PSG-RDI ≥ 20). Multivariate analyses revealing that body mass index (BMI) as well as DSI correlated well with PSG-RDI, we established a new criterion by adding the BMI score (DSI ≥ 15 or BMI ≥ 25), which remarkably improved the sensitivity. This criterion may be useful not only in clinical practice but also in medical checkups for asymptomatic patients, and also suggests that obese patients with sleep disturbance should undergo PSGs, irrespective of the DSI score.

Bronchial hyperresponsiveness and exhaled nitric oxide in patients with cardiac disease.

Background: Increased concentrations of exhaled nitric oxide (NO) correlate with increased airway inflammation and measurement of exhaled NO is a noninvasive method for the management of bronchial asthma. In various cardiac diseases, bronchial hyperresponsiveness is observed, as is bronchial asthma. However, there have been few studies on the relationship between exhaled NO and bronchial responsiveness in cardiac diseases. Objective: The aim of this study was to clarify the association between exhaled NO and bronchial hyperresponsiveness in patients with cardiac disease. Methods: We measured expired NO and bronchial responsiveness to inhaled methacholine in 19 patients with cardiac diseases and 17 with bronchial asthma. We divided the cardiac disease patients into two groups according to their bronchial responsiveness to inhaled methacholine: BHR(+) group consisted of 12 patients with bronchial hyperresponsiveness and BHR(–) group consisted of 7 patients without bronchial hyperresponsiveness. Results: The concentration of exhaled NO in the asthmatic patients was significantly higher than that in the BHR(+) and BHR(–) groups (142.0 ± 17.0, 33.6 ± 6.4 and 42.3 ± 10.3 ppb, respectively, p < 0.01). There was no significant difference in exhaled NO between BHR(+) and BHR(–) groups. There were also no significant differences in the parameters of bronchial hyperresponsiveness between the cardiac BHR(+) and bronchial asthma groups. These results indicate that bronchial hyperresponsiveness in patients with cardiac diseases is not a consequence of eosinophilic inflammation or of exhaled NO. Conclusion: We conclude that bronchial hyperresponsiveness in patients with cardiac diseases can occur independently of NO production.

A Case of Granulomatosis with Polyangiitis (Wegener's Granulomatosis) Presenting with Marked Inflamed Tracheobronchial Mucosa

A 70-year-old man was admitted to our hospital because of weight loss and persistent dry cough. Chest radiograph and CT showed multiple infiltrates in the bilateral upper lobes and the remarkably thickened bronchial walls. Bronchoscopy revealed diffuse erythema and edema of the tracheobronchial mucosa without any ulcerous legions. Serum MPO-ANCA was positive (155 EU). Transbronchial biopsy was performed and revealed necrotic granulomas with multinucleated giant cells in the bronchial/bronchiolar and parenchymal lesions. Thus, we diagnosed it as a localized form of granulomatosis with polyangiitis (GPA, Wegeners granulomatosis). After treatment with corticosteroid and cyclophosphamide, the bronchial findings were entirely resolved. We report here a rare case of GPA presenting with markedly inflamed tracheobronchial mucosa.