RESUMEN
Objective To study the mechanism of anti-inflammatory effects of licorice flavonoids(LF) isolated from the roots of Glycyrrhiza uralensis(licorice) on lipopolysaccharide(LPS)-induced lung inflammation in mice.Methods Mice were intratracheally instillated with either LPS(4 mg/kg) or saline.At 6 or 24 h after LPS intratracheal instillation,pathological examination and bronchoalveolar lavage were performed and the lung wet/dry weight ratio as an index of acute lung injury was assessed.Then,the numbers of total leukocytes,neutrophils and the activity of superoxide dismutase(SOD) and TNF-? protein in bronchoalveolar lavage fluid(BALF) were measured.LPS-induced myeloporoxidase(MPO) activity and expressions of TNF-? and IL-1? at the mRNA levels and TNF-? at the protein level in lung tissues were determined by RT-PCR and ELISA.Results LPS caused a severe lung inflammation,as indicated by the pathological findings and the lung wet/dry weight ratio.However,oral LF could attenuate these LPS-induced abnormalities.LF could decrease the numbers of total leukocyte cells and neutrophils,and increase the levels of SOD and TNF? BALF.In addition,LF significantly suppressed the MPO activity,TNF-? and IL-1? mRNA expression levels,and TNF-? protein level in the lung tissues.Conclusion Inhibition of inflammatory cytokines expressions and regulation of oxidation/antioxidation of LF may be its anti-inflammatory mechanism in LPS-induced lung inflammation in mice.