Objective To evaluate the effect of heme oxygenase-1 (HO-1) protein transduction on acute lung injury in septic rats.Methods Eighteen healthy male Sprague-Dawley rats,aged 7-9 weeks,weighing 210-260 g,were randomly allocated into 3 groups (n =6 each) using a random number table:sham operation group (group Sham),sepsis group (group Sep),and fusion protein PEP-1-HO-1 group (group HO).Sepsis was produced by cecal ligation and puncture (CLP).In group HO,PEP-1-HO-1 fusion protein 0.6 mg was injected via the left iliac vein at 1 h before CLP and 5 h after CLP.The equal volume of normal saline was given instead of PEP-1-HO-1 in Sham and Sep groups.At 12 h after CLP,blood samples were collected from the right common carotid artery for measurement of serum tumor necrosis factoralpha (TNF-α) and interleukin-6 (IL-6) concentrations.The rats were then sacrificed,and lungs were removed for microscopic examination and for determination of wet/dry lung weight ratio (W/D ratio) and malondialdehyde (MDA) content (by thiobarbituric acid colorimetric method).Results Compared with group Sham,the W/D ratio and MDA content were significantly increased,the serum TNF-α and IL-6 concentrations were significantly increased (P＜0.05),and the pathological changes were significantly aggravated in Sep and HO groups.Compared with group Sep,the W/D ratio and MDA content were significantly decreased,the serum TNF-α and IL-6 concentrations were significantly decreased (P＜0.05),and the pathological changes were significantly attenuated in group HO.Conclusion HO-1 protein transduction can attenuate acute lung injury in septic rats,and the mechanism is probably related to inhibition of lipid peroxidation in lung tissues and systemic inflammatory responses.