Abstract
The aim of the present study was to examine the protective effect of caveolin‑1 (Cav‑1) in the penehyclidine hydrochloride (PHC)‑based inhibition of lipopolysaccharide (LPS)‑induced acute lung injury (ALI) in vivo and in vitro, in addition to the potential underlying mechanisms. In vivo, an ALI rat model was established via intratracheal administration of LPS (5 mg/kg), and PHC (2 mg/kg) was administered 30 min following LPS treatment. In vitro, the Cav‑1 gene was knocked down by small interfering (si)RNA in J774A.1 cells. Cells were incubated with LPS (1 µg/ml) for 2 h, and subsequently incubated with PHC (2 µg/ml) for an additional 2 h. Lung injury was assessed by lung histology and the ratio of polymorphonuclear leukocytes (PMNs) to total cells was assessed in bronchoalveolar lavage fluid (BALF), myeloperoxidase (MPO) activity, BALF protein content and lung wet/dry (W/D) ratio. The levels of pro‑inflammatory factors, including tumor necrosis factor‑α (TNF‑α), interleukin (IL)‑6 and IL‑1β, in the sera of rats and cell culture supernatant were determined by ELISA. The protein expression levels of Cav‑1, toll‑like receptor 4 (TLR4), phosphorylated (p)‑p38 mitogen activated protein kinases (p38 MAPKs) and nuclear factor kappa‑light‑chain‑enhancer of activated B cells transcription factor p65 subunit (NF‑κB p65) in lung tissues and J774A.1 cells were analyzed by western blot analysis. The results indicated that PHC effectively alleviated lung injury by decreasing neutrophil infiltration and protein concentration in BALF, and the lung W/D ratio and MPO activity and pro‑inflammatory cytokine production induced by LPS. Furthermore, PHC significantly decreased the degrees of histopathological changes and pulmonary dysfunction. In vitro, treatment with PHC inhibited pro‑inflammatory cytokine levels and MPO activity in LPS‑stimulated J774A.1 cells. However, the results in the J774A.1 cells with Cav‑1 gene knockdown were contrary. In addition, PHC decreased TLR4, p‑p38 MAPKs and nuclear NF‑κB p65 expression levels and upregulated the expression level of Cav‑1, in vivo and in vitro. These data demonstrated that PHC exhibited a protective effect against LPS‑induced ALI in rats and LPS‑stimulated J774A.1 cells, which may be due to the inhibition of p38 MAPKs phosphorylation and TLR4/NF‑κB signaling pathway by Cav‑1 upregulation.