Establishment of rat model of silicotuberculosis and its pathological characteristic

Objective: To establish different stages of silicosis rat model complicated with tuberculosis infection, and compare the pathological characteristics and analyze the impact of silicosis on tuberculosis infection. Methods: SD rats were subjected to intratracheal administration of silica with non-exposure method at the 1st, 30th, or 60th day. At the 50th day, the rats were injected with the suspension of H37Rv (a virulent standard strain of Mycobacterium tuberculosis) via tail-vein. After 40 days post-infection, rats were sacrificed, the lung tissues were isolated, and paraffin was embedded and sectioned. The sections were treated using HE staining for structure observation, acid fast stain of Ziehl-Neelsen for bacterial detection, and Warthin-Starry silver staining for displaying the distribution of dust particles. The bacterial load was quantified by colony counting. Results: Primary to tertiary silicosis could be discovered at the 30th, 60th, and 90th day of post-infection. The rats could be infected by injection of M. tuberculosis via tail vein, with tuberculosis load and the degree of lung tissue lesions positively correlated with silicosis. Conclusion: The rat model of silicotuberculosis was established successfully, which facilitated understanding the 'cross-talk' of silicosis and tuberculosis during the process they drive each other.