Lipopolysaccharide regulates the expression of thymocyte differentiation antigen-1 and integrin β3 of lung fibroblasts and inhibit autophagy

Objective To clarify the effect of lipopolysaccharide (LPS) on the expression of thymocyte differentiation antigen-1(Thy-1) and integrin β3 in mouse lung fibroblasts and its relationship with autophagy inhibition. Methods Primary cultured mouse lung fibroblasts were divided into four groups (n=3) based on different concentration of LPS stimulation: PBS control group (Con group), 0.25 mg/L LPS group (LPS0.25 group), 0.50 mg/L LPS group (LPS0.50 group), 1.00 mg/L LPS group (LPS1.00 group). Then the total cellular proteins were extracted. The expression of Thy-1 and integrin β3 were detected by Western blot. The expression of autophagy-related proteins LC3-Ⅱ/Ⅰ and Beclin-1 in cells was compared at 30 h after LPS stimulatin. The formation of autophagic bodies was observed by using transmission electron microscopy. Results Thy-1 protein expression was decreased in lung fibroblasts with increasing concentration of LPS stimulation. Compared with the control group(P<0.05), the level of Thy-1 protein in lung fibroblasts was significantly decreased in 1.00 mg/L LPS group. Integrin β3 protein expression was increased with increasing concentration of LPS stimulation. As a result, the expression leve of integrin in 1.00 mg/L LPS group was significantly higher than the level in control group (P<0.05). At the same time, LPS significantly inhibited the expression of autophagy-related proteins LC3-Ⅱ/Ⅰ(P<0.05) and Beclin-1 (P<0.05) in mouse lung fibroblasts and the formation of autophagic bodies(P<0.05). Conclusions LPS can down-regulate the expression of Thy-1 but up-regulate the expression of integrin β3. It also inhibits the expression of autophagy-related proteins LC3-Ⅱ/Ⅰ, Beclin-1 and the formation of autophagic bodies. This process may be associated with LPS-induced autophagy inhibition of lung fibroblasts and the progress of lung fibrosis. Key words: Lipopolysaccharide; Lung fibroblasts; Autophagy; Thymocyte differentiation antigen-1; Integrin β3