The role of expression of TLR 4 in bleomycin-induced pulmonary fibrosis in mice

Objective To investigate the role of Toll-like receptor 4(TLR-4) in mice with lung fibrosis induced by bleomycin. Method Sixty mice were equally randomized into two groups, the lung fibrosis model was established by intratracheal lavage of bleomycin (5mg/kg) in lung fibrosis group, the contol group was given saline instead of bleomycin. On the 7, 14 and 21 days, The mRNA and protein expressions of TLR4 in lung tissue were assessed by real-time polymerase chain reaction(Real-time PCR) and western blot, respectively. In addition, the lung pathological changes were observed on collagen content, neutrophil and monocyte accumulation, and pulmonary fibrosis. Results Lung injury scores of lung fibrosis for 14 days and 21 days were significantly higher than that of the control group(P Conclusion These results indicate that TLR4 play an important role in lung inflammation after chemical-induced lung injury. In addition, TLR4 was activated again in the lung fibrosis period, which imply a novel concept for TLR4 in the pathophysiology of lung fibrosis.