| Bronchial asthma is a frequently encountered respiratory disease with increasing worldwide incidence and significant morbidity and mortality. Chronic airway inflammation, airway hyperresponsiveness and airway remodeling are two key features of asthma. More recently it has been appreciated that there are important structural airway changes which have been grouped together under the term "airway remodeling". This airway remodeling has been speculated to be responsible for irreversible airflow obstruction and to be one of the factors that make the treatment of such patients difficult. Thus, understanding the mechanisms underlying airway remodeling is of great importance for the development of new and effective therapeutic strategies for asthma patients. In recent studies, it has been discovered that a wide variety of stimuli are involved in airway remodeling via an EGFR cascade. The roles of EGFR and its ligands in asthma are complicated, but important. Therefore, understanding the mechanisms that regulate the EGFR and its ligands has become an active area of research in attempts to understand airway remodeling in asthma, which is important in preventing and curing airway remodeling of asthma. The research established the chronic asthma model of mice. Observation was done on the Changes of airway structures, expression of EGFR in the lung and the ligands of EGFR in BALF. In vitro, Studies were done on the role of EGFR activation on the TGF-α,IL-13,TNF-α inducing proliferation of airway smooth muscle cells(ASMC).The possible mechanism would supply with new idea of preventing and curing airway remodeling. The study is divided into five parts.Part1 The Establishment of chronic mice asthma modelOBJECTIVE:To Establish the mouse model of chronic asthma. METHODS: BALB/c mice received an intraperitoneal injection of 20μg of OVA complexed alum on Days 0,7 and 14.Mice received an intranasal dose of 100μg OVA on Days 20,21,22,23,24,25,26,27,28,29,47,61,73,74,and 75. Normal pathological slides were also observed for pulmonary inflammation and thickness of airway wall and airway smooth muscle. WBC, EOS and Lymphocyte in BALF and airway responsiveness to adenosine or acetylcholine was detected. RESULTS:In chronic mice asthma model group by OVA immunization, There were dysphoria, tachypnoea, abdominal muscle spasm. Inflammatory cell accumulation around bronchi and vessels could been seen in slides. WBC,EOS and Lymphocyte in BALF and thickness of airway wall and airway smooth muscle increased. Airway responsiveness to adenosine or acetylcholine was higher than control. CONCLUSIONS: Sensitization and activation by OVA can successfully establish the mouse model of chronic asthma.Part2 The expression of EGFR and its ligands in chronic asthma miceOBJECTIVE: To investigate the role of EGFR system in airway remodeling in chronic mouse asthma. METHODS: Establish the chronic mice asthma model by OVA immunization. TGF-αin BALF by ELISA was detected. RT-PCR was done to detect mRNA level of EGFR in the lung. Pulmonary EGFR protein was observed by immunohistochemical staining and western blot analysis. RESULTS: In chronic mice asthma model group, TGF-αin BALF and the expression of EGFR mRNA and protein in the lung increased. CONCLUSIONS: In chronic mice asthma model group, EGFR system is activated.Part3 The role of TGF-α on the proliferation of airway smooth muscle cells and the mechanismOBJECTIVE: To study the role of TGF-α on the proliferation of airway smooth muscle cells and the mechanism. METHODS: Murine ASMC were isolated and subculture. EGFR protein was observed by immunohistochemical staining. MTT and 3H-TdR incorporation assays were used to evaluate the proliferation of airway smooth muscle cells after TGF-α were added. The effect of AG1478, 225mAb, U0126 and wortmannin on TGF-αinducing proliferation of airway smooth muscle cells was assessed by MTT assay and 3H-TdR incorporation assays. Added TGF-α with different concentrations and time , or together with AG1478, 225mAb, phospho-EGF receptor pr...
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