Abstract: The protective effect of ferulic acid (FA) on rat lung injury induced by PM2.5 in Beijing was studied in the present
investigation aiming to provide basic information for the prevention and control of health hazard caused by PM2.5. Rats
were treated with PM2.5 at different concentrations (1.5, 6.0, and 24.0 mg/kg) with and without pre-administration of FA.
Histopathological changes of lung tissue were detected by hematoxylin-eosin (HE) staining. Bronchoalveolar lavage fluid
(BALF) was collected to count the number of inflammatory cells and detect the expressions of lactate dehydrogenase (LDH),
alkaline phosphatase (AKP) and acidic phosphatase (ACP). Blood supernatant was used for measuring the levels of methane
dicarboxylic aldehyde (MDA), superoxide dismutase (SOD) and 8-hydroxy-2-deoxyguanosine (8-OHdG). The homogenate
supernatant of lung tissue was collected for detecting the concentrations of immunoglobulin E (IgE), tumor necrosis
factor-alpha (TNF-α), interleukin-4 (IL-4), interleukin-8 (IL-8), nuclear factor-kappa B (NF-κB) and Toll-like receptor-4
(TLR-4). The results showed that PM2.5 exposure caused a dose-dependent pathological change of lung tissue and an
increase in inflammatory cells in BALF. PM2.5 at 6.0 mg/kg caused the greatest damage. FA (38.8 mg/kg) prevented the
increase in the expressions of MDA and 8-OHdG as well as the concentrations of IgE, TNF-α, IL-4 and TLR-4, and the
decrease in SOD activity induced by PM2.5. Therefore, PM2.5 can cause significant oxidative damage and inflammatory
injury to the lung tissue in rats. These damages can be prevented by pre-administration of FA potentially through inhibition
of Toll-like receptor signaling.

Key words: ferulic acid, PM2.5, rats, lung injury, protective effect