Beneficial effects of Houttuynia cordata polysaccharides on “two-hit” acute lung injury and endotoxic fever in rats associated with anti-complementary activities

Lu, Yan; Jiang, Yun; Ling, Lijun; Zhang, Yunyi; Li, Hong; Chen, Daofeng

As a traditional Chinese medicine with actions of clearing heat and eliminating toxins, the whole plant of Houttuynia cordata Thunb. (Saururaceae) is commonly used for the treatment of pulmonary symptoms (including lung abscess, dyspnea, phlegm and cough), as well as infectious diseases, anaphylaxis, cancer and viral infection [14] [15] [16] [17] . A Chinese multiherb remedy with H. cordata as the principal ingredient had been used for the treatment and prevention of severe acute respiratory syndrome (SARS) in 2003 18 and was found to have significant anti-complementary activity 19 . Our previous study indicated that the crude H. cordata polysaccharides (CHCP) 20 and flavonoids 21 were the major anti-complementary principles of this plant. Some anti-complementary polysaccharides showed potent effects on complement-associated diseases in vivo 22, 23 . The presence of lipopolysaccharide (LPS), a prototypical endotoxin, in blood can cause the immediate activation of the complement cascade. We had reported that CHCP could ameliorate LPS-induced ALI in mice and reduce the complement activation products deposited in the lung tissue 20 . However, it is still unclear whether this effect was a direct result of CHCP's anti-complementary activity in vivo. Herein, the beneficial effect of CHCP on ALI was further evaluated using a "two-hit" ALI rat model induced by hemorrhagic shock plus LPS instillation, which is more susceptive to lung injury 24 . Specifically, the in vivo anti-complementary activity of CHCP was also assessed. Besides pulmonary infections, fever is another typical indication for heat-clearing traditional Chinese medicine (TCM). Therefore this paper investigated in vivo the anti-pyretic effects and anti-complementary activity of CHCP on a febrile rat model induced by LPS.