Abstract
The traditional Chinese medicine Platycodon grandiflorum (PG) is often used for the treatment of a number of chronic inflammatory diseases. In Chinese veterinary clinic, PG is always extracted by decoction and taken orally, however, the molecular mechanism of PG extract (PE) to reduce LPS-induced inflammation, especially acute lung injury (ALI) in vivo, are not known. Thus, we have studied the anti-inflammatory effects of PE on lipopolysaccharide (LPS)-induced acute lung injury via TLR4/NF-κBp65 pathway in rat. Sprague-Dawley rats were randomly divided into 4 groups: control group, LPS group, LPS±PE low dose group and LPS±PE high dose group. All rats were given corresponding PE solution or the same amount of normal saline by intragastric administration for 7 days. On the 7th day, 1 h after the last administration, 500 μg of LPS were introduced intratracheally to establish ALI rat model, and the same volume of normal saline was given to control group. The results showed that PE reduced the levels of LPS-induced pro-inflammatory mediators including IL-6, PGE2, and TNF-α, alleviated the lung injury histologically, and down-regulated LPS-induced mRNA and protein levels of TLR4/NF-κBp65 in lung tissue. This study demonstrated that PE has the anti-inflammatory effects on LPS-induced ALI in rats through TLR4/NF-κBp65 signaling pathway, indicating that PE is an effective suppressor for anti-inflammatory activities.