Study The Effect Of Exogenous IL-10 On Pulmonary Fibrosis Induced By Bleomycin In Mouse

Objectives To investigate the effect of IL-10 on pulmonary fibrosis mice model which were induced by bleomycin.Methods Forty-eight adult female C57BL/6J mice were randomly divided into eight groups:control groupⅠ,bleomycin groupⅠ,0th day of intervention group,7th day of intervention group,14th day of intervention group,control groupⅡ,bleomycin groupⅡ,28th day of intervention group. Each group has six mice. A dose of bleomycin (3.5mg/kg) was given to the six groups by single intratracheal instillation except two control groups. The 0th day,7th day and 14th day of intervention groups were treated by the intraperitoneal injection in a dose of 5μg/kg of IL-10 at the 0th,the 7th and the 14th respectively, three times a week for 2 weeks, and treated separately by normal saline three times a week at the other 2 weeks; The bleomycin groupⅠand control groupⅠwere treated separately by normal saline in the same volume of IL-10 at the 0th day, three times a week for 4 weeks; All the mice of the five groups were killed on the 28th day after models establishing. However, the 28th day of intervention group began to treated by the intraperitoneal injection in a dose of 5μg/kg of IL-10 and bleomycin groupⅡ,control groupⅡwere treated separately by normal saline in the same volume of IL-10 on the 28th day, three times a week for 2 weeks;the mice in the three groups were killed on the 42th day after model was established. The lungs tissues were harvested for histopathlogical examination and etermining the level of hydroxyproline. Immunohistochemistry was used to detect the expression of TGF-β1.Results (1)We succeeded in establishing the mouse model of pulmonary fibrosis by intratrachealing instillation of bleomycin. (2) The lung coefficient,hydroxyproline content,degree of pulmonary fibrosis and the expression of TGF-β1 in lung tissues were higher in the bleomycin groupⅠthan in the control groupⅠ.However, they were distinctly reduced after interfered by IL-10 in the 0th day,7th day and 14th day of intervention groups(p<0.05), but still higher than control groupⅠ(p< 0.05). Depending on the intervention of different periods, the lung coefficient, hydroxyproline content, degree of pulmonary fibrosis and the expression of TGF-β1 were decreased gradually in the 0th day,7th day and 14th day of intervention groups. But comparing with the control groupⅡ, the bleomycin groupⅡand 28th day of intervention group was increased evidently (p<0.01). However, there is no significant difference between the bleomycin groupⅡand 28th day of intervention group (p>0.05).Conclusions Exogenous IL-10 could significantly reduce the degree of bleomycin-induced pulmonary fibrosis in mice by reducing the expression of the TGF-β1. And the effect is the earlier the better, especially in the alveolitis phase and fibrosis formation stage. It suggests that IL-10 should be a therapeutic way for pulmonary fibrosis.