Construction of mouse models of invasive pulmonary aspergillosis and the expressionof γ-interferon, Toll-like receptor 2 and Toll-like receptor 4 / 中国组织工程研究

ABSTRACT

BACKGROUND:Pulmonary aspergilosis is a disease caused by pulmonary fungal infection. Its diagnosis and treatment is usualy delayed because of nonspecific clinical symptoms, physicial sign and imaging changes as wel as uncertainties of histological and bacterial findings. Therefore, it is necessary to establish mouse models of invasive pulmonary aspergilosis to investigate the underlying pathological mechanism and novel therapeutic methods. OBJECTIVE: To establish mouse models of invasive pulmonary aspergilosis, detect the expression ofγ-interferon, Tol-like receptor 2 and Tol-like receptor 4, and discuss the mechanism of action underlying invasive pulmonary aspergilosis. METHODS:Seventy-five female BALB/c mice of clean grade, aged 6-8 weeks, were randomly and evenly divided into five groups blank control group (group A), immunosuppressive model group treated with high concentrations of Aspergilus fumigatus spore suspension (group B), normal infection group treated with high concentration of Aspergilus fumigatus spore suspension (group C), immunosuppressive model group treated with low concentration of Aspergilus fumigatus spore suspension (group D), normal infection group treated with low concentration of Aspergilus fumigatus spore suspension (group E). First, mice in the groups B and D were intraperitonealy injected with cyclophosphamide to establish immunosuppressive models. The mice in the groups D, E (108 cfu/mL) and groups B, C (109 cfu/mL) were treated with 12 mL Aspergilus fumigatus spore suspension through the use of nebulizer. Mice in the group A were treated identicaly with sterile PBS. At 1, 3, 5 days of infection, the pathological change of lung tissue was observed, the mass concentration of γ-interferon in bronchoalveolar lavage fluid and the expression levels of γ-interferon mRNA and Tol-like receptor 2 and Tol-like receptor 4 mRNA and protein in the lung tissue were determined. RESULTS AND CONCLUSION:Abscess, spores and very severe bleeding and congestion, widenened alveolar septum and tracheal epithelial cel shedding and necrosis were observed in the mouse lung tissue in the group B. At 5 days of infection, the mass concentration of γ-interferon in bronchoalveolar lavage fluid and the expression ofγ-interferon mRNA in the lung tissue in the group B were significantly decreased compared with the group A (P < 0.05). Tol-like receptor 2 expression was strongly positive in the group B. Tol-like receptor 2 expression in the group C was significantly lower than that in the group B (P< 0.05). Tol-like receptor 4 expression was positive in the groups B and C, and its expression in the group C was significantly greater than in the group B (P < 0.05). The expression of Tol-like receptor 2, 4 mRNA in the mouse lung tissue of group B was significantly increased at 1, 3, 5 days of infection (P < 0.05). These results suggest that atomizing high concentration of aspergilus fumigatus spore suspension to immunosuppressive mice can establish stable invasive pulmonary aspergilosis models with typical pathological features. The infection of aspergilus fumigatus can activate tol-like receptor 2, 4 at the same time, and the pathological mechanism is closely related to organism’s immune defense function.