Protective effects of fucoidan against hyperoxic lung injury via the ERK signaling pathway

High oxygen mechanical ventilation is widely used to treat various lung diseases; however, it may result in hyperoxia, which induces inflammation and lung injury. Fucoidan is an extract of the seaweed Fucus vesiculosus, which has previously been reported to exert effects against diabetic nephropathy. The present study is the first, to the best of our knowledge, to investigate the protective effects of fucoidan against hyperoxic lung injury. Balb/c mice were ventilated with 100% oxygen, with or without the atomization inhalation of fucoidan, for 36 h. Hyperoxia reduced the body weight and increased the relative lung weight of the mice. In addition, cell quantity and differentiation were determined using a hemocytometer, hyperoxia increased the total number of cells, and the number of macrophages, neutrophils and lymphocytes in the bronchoalveolar lavage fluid. Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) demonstrated that hyperoxia also increased the mRNA expression levels of cluster of differentiation (CD)68, F4/80, CD64 and CD19 in lung tissue, and induced lung morphological alterations. Furthermore, western blotting assay demonstrated that hyperoxia increased the expression levels of interleukin (IL)‑1, IL‑6 and tumor necrosis factor (TNF)‑α, and the phosphorylation of extracellular signal‑regulated kinase (ERK)1/2. Conversely, hyperoxia‑induced inflammation and morphological alterations were significantly attenuated in the mice treated with fucoidan. Atomization inhalation of fucoidan also reduced the hyperoxia‑induced expression of IL‑1, IL‑6 and TNF‑α, and the phosphorylation of ERK1/2. These findings suggested that fucoidan may attenuate hyperoxic lung injury via the ERK1/2 signaling pathway.