The role of dependent pathway in eosinophil apoptosis / 천식및알레르기

BACKGROUND: Interleukin-5 (IL-5), IL-3, and GM-CSF are known to prolong the survival of eosinophils, and IL-5 has the most potent effect on eosinophil survivaL It is also known that divergent signals induce apoptosis in different cells. But, There have been few reports on about the intracellular signals that trigger the effectors of apoptosis. Cyclic AMP (cAMP) can modulate apoptosis in many cells. But, the role of intracellular cAMP in the IL-5 induced eosinophil survival is still not completely understood. OBJECTIVES: This study was aimed to elucidate the role of intracellular cAMP in IL-5 induced eosinophil survival. MATERIAL AND METHOD: Eosinophils were isolated from peripheral blood of atopic patients. Eosinophil viability was measured by means of propidium iodine (PI) method and the number of viable cells was counted by FAC scan (Becton Dickinson, USA). Cells were cultured with or without IL-5, and also with various cAMP-elevating agents (dibutyryl cAMP, 8-bromo-cAMP, N6- benzoyl cAMP). The concentrations of cAMP were measured by cAMP enzyme immunoassay system(BiotrakTM, Amersham). Finally cAMP dependent protein kinase A inhibitor (H8) was added to eosinophils to examine the effect of decreased intracellular cAMP activity on the viability of eosinophils stimulated with IL-5. RESULTS: The percentage of viable eosinophils was reduced rapidly from 92.1+/-1.8% to 8.23+/- 3.41% without IL-5 (p<0.05; n=ll, 4-day incubation). Upon addition of IL-5, it was increased to 33.02+7.8% (p<0.05; n=ll). In the absence of IL-5, the addition of cAMP-elevating agent increased eosinophil viability in a dose-dependent manner. Upon addition of H8 (24 uM), the eosinophil viability increased by IL-5 (52.5+/-6.4%) was significantly reduced to 27.2+/-5.4% (p<0.05;n=7). Compared with tissue culture media (TCM) only, IL-5 produced persistent elevation of intracellular cAMP of eosinophils in a time and dose dependent manner.

Effect of theophylline on Bc 1 - 2 expression of Il - 5 stimulated eosinophil / 천식및알레르기

BACKGROUND AND OBJECTIVE: Eosinophil is a major inflammatory cell in allergic diseases and parasitic infestations. Various cytokines such as GM-CSF, IL-3 and IL-5 are known to activate eosinophils and prolong their survival. Among them, IL-5 is the most potent stimulator of eosinophil survival. Recently, it was reported that increased expression of Bcl-2 is related to prolonged survival of IL-5 stimulated eosinophil. Theophylline is a useful drug in bronchial asthma, due not only to bronchial dilation but also to its anti-inflammatory effects. It has been suggested that anti inflammatory action of theophylline derives from the reduction of inflammatory cells in the airways which is mechated by stimulat on of apoptosis of inflammatory cells. In this study, we investigated, by measuring Bcl-2 expression of IL-5 stimulated eosinophil, the effect of theophylline on apoptosis as one of the anti-inflammatory action. MATERIAL AND METHOD: Peripheral eosinophils were isolated from atopic patients by using Perco- 11 discontinuous gradient and purified by negative selection technique using MACS. Eosinophil viability and apoptosis were measured by FACscan. Expression of Bcl-2 protein in eosinophils was detected by Western blot and ELISA. RESULTS: IL-5 increased the percentage of viable eosinophils and reduced the apoptosis of eosinophils in a dose dependent manner. The increased survival of IL-5 stimulated eosinophils was reduced by theophylline via activation of apoptosis. Bcl-2 was increased when eosinophils were cultured with IL-5 only, but when theophylline was cocultured, reduced Bcl-2 was seen with Western blot and ELISA. CONCLUSION: IL-5 increases the survival of eosinophil through the enhanced expression of Bcl- 2. Theophylline has counter action against IL-5 via inhibition of Bcl-2 induced by IL-5. Inhibiting the prolongation of eosinophil survival caused by IL-5 might be one possible mechanism of antiinflammatory effects of theophylline.

Silica induced Expression of IL-1beta, IL-6, TNF-beta, TGF-alpha, in the Experimental Murine Lung Fibrosis / 결핵

BACKGROUND: Silica-induced lung diseases is characterized by the accumulation of inflammatory cells at early stage and fibrosis in pulmonary parenchyma and interstitium at late stage. As a consequence of inflammation, silicosis is accompanied with the expansion of interstitial collagen and the formation of fibrotic nodule. In this process, several kinds of lung cells produce cytokines which can amplify and modulate pulmonary fibrosis. The alveolar macrophage is a potent source of proflammatory cytokines and growth factor. But in the process of silicotic inflammation and fibrosis, there are many changes of the kinetics in cytokine network. And the sources of cytokines in each phase are not well mown. METHOD: 2.5 mg of silica was instillated into the lung of C57BL/6J mice. After intratracheal instillation of silica, the lungs were removed for imunohistsochemical stain at 1. 2,7 day, 2, 4,8, 12 week, respecilvely. We investigated the expression of IL-1beta, IL-6, TNF-alpha and TGF-beta in lung tissue. RESULTS: 1) The expression of IL-6 increased from 1 day after exposure to S weeks in vascular endothelium. Also peribronchial area were stained for IL-6 from 7 days and reached the peak level for 4 weeks. 2) The IL-1beta was expressed weakly at the alveolar and peribronchial area through 12 weeks. 3) The TNF- expressed strongly at alveolar and bronchial epithelia during early stage and maintained for 12 weeks. 4) TGF-beta was expressed strongly at bronchial epithelia and peribronchial area after 1 week and the strongest at 8 weeks. CONCLUISON: The results above suggests IL-6, TNF- appear to be a early inflammatory response in silica induced lung fibrosis and TGF-beta play a major role in the maintenance and modulation of fibrosis in lung tissue. And the regulation of TNF- production will be a key role in modultion of silica-induced fibrosis.