| Summary: | 碩士 === 國立成功大學 === 微生物及免疫學研究所 === 94 === Asthma is a chronic inflammatory disease of the bronchial airways orchestrated by Th2 T cells and their secreted cytokines. In previous studies, major allergens of Dermatophoides pteronyssinus (Der p) have been identified as a group of proteolytic enzymes, which may cause airway epithelial barrier disruption to contact with airway mucosa mast cell, and releasing preformed or newly synthesis, mediators, such as histamine, tryptase, and evoke the allergen-induced airway inflammation. Mast cell tryptase has potent biologic activities that may contribute to the inflammatory response and airway hyper-reactivity seen in asthma. Moreover, tryptase can activate protease-activated receptor-2 (PAR2), a G protein-coupled receptor that expressed on lung endothelial or epithelial cells, which has important role in the control of airway inflammation and smooth muscle cells proliferation. It is reasonable to suggest that protease inhibitors, particularly for tryptase inhibitor, may attenuate allergenic inflammatory response. In this study, we investigated the effects of protease inhibitors: Nafamostat Mesilate (FUT) and Gabexate Mesilate (FOY), both are serine protease inhibitors and Ulinastatin (UTI), a human urinary trypsin inhibitor, on airway inflammation in a mouse model of allergic asthma. We hypothesized that serine protease inhibitors might inhibit Der p-elicited airway inflammation in a mouse model of asthma. The purpose of this study was to determine the prevention and therapeutic potential or influence of allergenicity of Der p of protease inhibitors on allergy airway inflammation in a mouse model of asthma. The preventive protocol 1 results showed that both FUT and FOY could inhibit total cells counts、eosinophils and neutrophils infiltration and inhibition PAR-2 expression in the BALF, and attenuated Der p-induced Th2 cytokines production and reduced serum IgE levels. In addition, FUT inhibited the iNOS and CD86 expression of alveolar macrophage stimulated with Der p as shown by fluorescence microscope. But, only FUT-treated mice showed a significant change of mast cell activation and airway hyperresponsiveness (AHR). However, UTI-treated mice did not have significantly change in a mouse model of asthma. In the therapeutic experiment of protocol 2, the results showed similar pattern as protocol 1 in decreasing total cell counts, neutrophils, and eosinophils in the BALF of FUT- and FOY-treated mice. The concentrations of Der p-specific IgG1 also showed markedly decreased pro-inflammatory cytokines TNF-α, and IL-12 increased in the BALF on FUT- and FOY-treated mice. Both FUT- and FOY-treated mice showed significantly decrease of mast cell activation of mMCP-1 release and airway hyperresponsiveness (AHR). Only FUT-treated mice showed a significant decrease of PAR-2 expression in the BALF. However UTI-treated mice did not have significantly change in a mouse model of asthma. The protocol 3 results showed a similar pattern as protocol 2 in decreasing total cell counts, neutrophils, and eosinophils in the BALF of FUT- and FOY-treated mice. Only FUT-treated mice showed attenuated IL-4 and IL-6 production, while UTI-treated mice showed increase TNF-α production. Both FUT- and FOY-treated mice showed significantly decreased AHR and inhibited PAR-2 expression in the BALF.
The second part of our studies was focus on MH-S (mouse alveolar macrophage) and P815 (mouse mast cell) cell lines that stimulated with Der p、LPS、AP (PAR-2 agonist)、RP (PAR-2 antagonist)、trypsin (PAR-2 activator) to observe the effects of protease inhibitors on PAR-2 expression. Both of cell lines stimulated with Der p、LPS、AP、RP in 12 or 24 hours did not have significantly difference in PAR-2 expression. When stimulated with AP 10μM 6 hours and 100μM 24 hours, MH-S cells showed PAR-2 highest expression. Stimulation on P815 cell with above reagents did not have significantly difference in PAR-2 expression. Therefore, we suspect that the anti-inflammatory effect in a asthma model of FUT and FOY may via the influence of allergenicity of Der p、mast cell activation in the airways to reduce allergic airway inflammation and cytokine production. We also found FUT and FOY inhibited PAR-2 activation in BALF from the animal model of asthma. The mechanism of this suppression effect of serine protease inhibitors on allergic airway inflammation is still unclear. Such properties of protease inhibitors might be useful in combination, or as an alternative treatment on allergic disease.
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