Interleukin 4 In The Pathogenesis Of Bronchial Asthma

Asthma is one of the serious health problems. Its morbidity and mortality have increased since 1980s. A lot of investigations have been done, but the pathogenesis of asthma still remained unsolved.The imbalance of Th1/Th2, increase of the production of Th2-cytokines (such as IL-4, IL-5) and decrease of the production of Th1-cytokines (such as IFN-r), plays important role in the pathogenesis of asthma. Many studies have been done to elucidate the role of IL-4 in pathogenesis in asthma, and mainly focused on the activation of B lymphocyte, production of IgE and so on. Only a few attentions was paid to the effect of IL-4 on airway remodeling.In present study, imbalance of Thl/Th2 was identified and the correlation between IL-4 level and clinical findings was observed in asthmatic patients. The effects of IL-4 on the proliferation of airway smooth muscle cells (ASMC), the expression of PDGF-b and ICAM-1 in ASMC were estimated. The effects of IL-4 on signal transduction pathway, intracellular free calcium and activation of protein kinase C (PKC), were also examined. Finally, effects of several drugs on above changes induced by IL-4 were compared.The main results were showed as follows:1. The increase of production of IL-4 and the decrease of production of IFN-r were found in peripheral blood mononuclear cells (PBMC) from asthmatic children, which resulted in the reduction of Thl/Th2. The level of IL-4 was positive correlated to total serum IgE and was negative correlated to FEV1. These results suggested there is an imbalance of Thl/Th2 in asthmatic children, and the level of IL-4 is related to clinical findings. BCG-PSN and dexamethasone could alleviate the imbalance of Thl/Th2.2. IL-4 could increase the numbers of ASMC by using MTT assay. The similar result was also observed by using [~3H]-thymidine (TdR) incorporation assay. These results...