Abstract: Objective To observe the protective effect and molecular mechanism of C-phycocyanin (CPC) on acute lung injury in septic rats. Methods Rats were randomly divided into control group, model group and CPC group. Cecal ligation and puncture was used to establish a septic acute lung injury rats (model group). For the CPC groups, septic acute lung injury rats were administrated by 20,40 and 60mg/kg of CPC by peritoneal injection. 72h after the operation, serum and lung tissue were obtained, the PaO2/FiO2, the wet to dry weight ratio, content of tumor necrosis factor (TNF)-α、interleukin (IL)-6 and IL-10 in bronchoalveolar lavage fluid, the concentration of malondialdehyde (MDA) and activity of myeloperoxidase (MPO) was analyzed. Enzymic activity of heme oxygenase (HO)-1 and its mRNA was detected by colorimetric method and RT-PCR, respectively. Results The PaO2/FiO2, the content of MDA, activity of MPO, and thewet to dry weight ratio was increased in the model group, and it was statistically significant than that in the control group (P<0.05), after CPC treatment, the level of PaO2/FiO2 increased, the wet to dry weight ratio and the content of MDA and activity of MPO decreased (P<0.05), In the medel group, TNF-α、IL-6 and IL-1β in bronchoalveolar lavage fluid was increased, HO-1 acivity and mRNA level was also increased(P<0.05). CPC could decrease the cytokines level, and upregulate HO-1 acitvity and mRNA expression. In addition, HO-1 agonist CoPP could synergize CPC to production of TNF-α、IL-6 and IL-10 1β, but HO-1 antagonist ZnPP could futher increase the cytokines production. Conclusion CPC could induce HO-1 expression, and thus relieve gas exchange function and the inflammatory response in the septic acute lung injury.

Key words: C-phycocyanin, sepsis, acute lung injury, heme oxygenase-1