Detection of IL-1β, IL-6 and TNF-αin Sprague-Dawely rats’ atrophic thymus induced by lipopolysaccharide

Objective: This study aimed to investigate developmental changes of the thymus and intrathymic IL-1β, IL-6 and TNF-α expression in weaned Sprague-Dawley rats induced by lipopolysaccharide.Methods: Forty healthy weaned rats aged 26 days and weighing 83±4 g were randomly and equally divided into two groups.The lipopolysaccharide group was treated daily with a single injection of lipopolysaccharide for 10 consecutive days, and the saline group was treated with an equal volume of sterilized saline.On the 1 st , 4 th , 7 th and 10 th day, histological changes and distribution of IL-1β-, IL-6-and TNF-α-positive cells were detected in the thymus by hematoxylin-eosin and immunohistochemistry staining, respectively.Subsequently, the expression levels of IL-1β, IL-6 and TNF-α were evaluated in the thymus by the ELISA method.Results: Thymus weight and index were significantly smaller in lipopolysaccharide-treated rats than in saline-treated rats (p<0.05),but no substantial changes were found in the thymus microstructure after lipopolysaccharide induction.Moreover, a large number of IL-1β-, IL-6-and TNF-α-positive cells were observed with brownish-yellow color and mainly distributed in the thymus parenchyma, both integrated optical density and average optical density increased significantly in lipopolysaccharide-treated rats than those in saline-treated rats.Compared with the saline group, most of the thymic homogenates had higher levels of IL-1β, IL-6 and TNF-α in the lipopolysaccharide group on different days. Conclusion:These findings indicate that the thymus atrophied after lipopolysaccharide induction in weaned Sprague-Dawley rats, and excessive production of intrathymic IL-1β, IL-6 and TNF-α was probably involved in the atrophic process.