1. We examined the effect of Saiboku-to (Chai-pu-tang, TJ-96), a traditional herbal medicine, on the late asthmatic response (LAR) and the expression of proinflammatory cytokines including tumor necrosis factor (TNF)-alpha, interleukin (IL)-1alpha, beta, granulocyte-macrophage colony stimulating factor (GM-CSF) in a guinea-pig asthmatic model sensitized by ascaris suum extract. TJ-96 significantly suppressed the LAR and the infiltration of eosinophils and mast cells/basophils. The immunohistochemistry revealed the reduction of these cytokine expression in the TJ-96 treatment group in which LAR was suppressed.
2. To understand the mechanism of eosinophil migration to the site of inflammation, we examined the expression of adhesion molecules in the bronchial tissues of asthmatic subjects. Mac-1, LFA-1 and VIA-4 were strongly positive in eosinophils and mononuclear cells infiltrated in the bronchial mucosa and submucosa. ICAM-1 and VCAM-1, the ligand of Mac-1/LFA-1 and VLA-4, respectively,
and E-selectin were detected in the endothelial cells of capillaries and venules. In situ hybridization and immunoelectron microscopic study demonstrated that ICAM-1, VCAM-1 and E-selectin were newly synthesized prior to spontaneous asthma attacks. These results suggest that their expression, particularly that of VCAM-1, may play a key role in eosinophil infiltration into the airway.
3. We examined the effects of traditional herbal medicines used for allergic diseases and various anti-allergic agents on the proliferation and differentiation of human basophilic leukemia cell line KU 812F.A suppressive effect on the growth of KU812F cells was found, the order of potency b being Saiboku-to, Shoseiryu-to, Bakumondo-to, Seihai-to. Saikosaponins Sa, Sd, baikalein, azelastine, anlexanox and disodium cromoglycate also suppressed at 1-10muM,while saikosaponin Sc, ginsenosides Rb1 and Rg1, ketotifen and tranilast did not show any effect even at 10muM.These results suggest that traditional herbal drugs may affect allergic diseases by suppressing the growth/differentiation of basophils/mast cells.
4. To determine the mechanism responsible for nitrogen dioxide (NO2)-induced airway hyperresponsiveness, we examined the efects of NO2 exposure on the contractile response to histamine and the level of histamine N-methyltransferase (HMT) activity, a histamine-degrading enzyme, in gunea pig trachea. HMT activity was decreased by 12 h, but exceeded the control value by 96 h exposures of NO2.
Contractile response to histamine, but not to acetylcholine, was increased by 12 h exposure, while the response decreased by 96 h exposure in which HMT mRNA level was increased. These results suggest that NO2-induced transient smooth hyperresponsiveness to histamine is due to the decreased capacity of histamine catabolism in airway.
5. To investigate the contribution of interleukin (IL)-5, IL-8 and granulocyte-macrophage colony stimulating factor (GM-CSF) to sirway inflamation, we compared the cellular differential and immunolocalization of these cytokines in sputum cells from patients with bronchial asthma and chronic bronchitis. The immunochemical comparison of GM-CSF and IL-8 localization in sputum cells between bronchial asthma/chronic bronchitis suggests the differential regulation and roles of these cytokines in eosinophilic vs neutrophilic airway inflammation, resulting in the development of different types of airway inflammation.
6. We investigated the localization of mRNA and protein of platelet-derived growth factor (PDGF), which may contribute to the hypertrophy of airway smooth muscle cells and basement membrane, in nasal polyp (NP) tissues and bronchial tissues from mild and severe asthmatics. The expression of PDGF was increased in NP and severe asthma tissues. The vast majority of cells expressing PDGF were eosinophils.
Our results showed for the first time that eosinophils are synthesizing PDGF in chronically inflamed airway diseases such as nasal polyposis and bronchial asthma. Less