Improvement and evaluation of chronic bronchitis modeling methods in mice

AIM: To explore a more accurate and reliable pathological model of the chronic bronchitis, which has improved from the former single-factor modeling method of the disease.METHODS: The mice in complex group were treated with lipopolysaccharide(LPS) by tracheal injection on the 1st day and nasal drops on the 14th day, and from the 2nd day to 30th day, the animals were given passive smoking and sulfur dioxide(SO₂) inhalation(except on the 14th day). The mice in SO₂ group were exposed to SO₂ 2 min per day, while in smoking group, the mice were exposed to smoke for about 1 h per day(4 cigarettes each time until one pack of cigarettes were burning up). In LPS group, the mice had tracheal injection of LPS on the 1st day and nasal drops of LPS on the 14th day and 30th day. Every modeling process lasted for 30 days. After modeling, the improvement of chronic bronchitis model was evaluated by testing the general conditions of the mice, analyzing leukocyte count in bronchoalveolar lavage fluid(BALF), and observing the morphological changes of the bronchial and lung tissues.RESULTS: After modeling, the mice in every model group experienced symptoms including wet nose, cough, dry and lusterless hair, arched back and curled-up body, showing inactive, and slow down in response. The mice in complex group gained the lowest weight compared to other groups. From each model group, the inflammatory cells infiltrated evidently around the bronchial walls, especially in the bronchial cavity, and the mucilage secretion in the airway increased. The total number of leukocytes in BALF increased significantly in complex group. The inflammatory cell count in the lung tissue indicated that the mice in complex group had significantly higher levels of inflammatory cell infiltration. Besides, the comparison between smoke group and LPS group was statistically significant.CONCLUSION: Smoking, SO₂ inhalation and LPS injection induce bronchial lung disease in mice, and the complex chronic bronchitis mouse model is a better model with the pathological changes of bronchus, lung tissue and BALF, and pathogenesis of chronic bronchitis.