OBJECTIVETo explore the protective effect of high density lipoprotein on the lung function of rats with severe burns.

METHODSOne hundred and thirty-five Wistar rats were employed in the study and were randomly divided into control (n = 15, without injury), burn (n = 60, with 30% TBSA full-thickness burn on the back) and experimental [(n = 60, with the injection of HDL (80 mg/kg) via the caudal vein immediately after burns)] groups. The rats in the latter two groups were resuscitated with intraperitoneal isotonic saline (50 ml/kg) 30 minutes after burns. The serum content of ICAM-1 and TNF-alpha as well as the blood content of PCO2 and PO2 of the rats in burn and experimental groups were determined at 12, 24, 48 and 72 post-burn hours (PBH) and in control group. The pathological changes in the lung tissue of the rats in all groups were observed under light microscope and electronic microscope at 48 PBH.

RESULTSPCO2 and the contents of ICAM-1 and TNF-alpha in burn group were significantly higher, but the PO2 was lower than those in control group at each time-point (P < 0.05 or P < 0.01). There were no obvious differences in the above indices between the experimental and control groups (P > 0.05), but the ICAM-1 and TNF-alpha levels in experimental group were markedly decreased than those in burn group at each time-point (P < 0.05 or P < 0.01). The ICAM-1 and TNF-alpha contents in burn group at 48 PBH were (3.42 +/- 0.25) microg/L and (4. 04 +/- 0.28) ng/L, respectively, which were markedly higher than those in experimental group [(2.24 +/- 0.14) microg/L, (3.35 +/- 0.22) ng/L, P < 0.05 or P < 0.01]. Dilation of capillaries, congestion and inflammatory infiltration in the pulmonary capillaries, and loosening of conjunction between pulmonary capillary vascular endothelial cells and endothelial swelling were observed in burn group at 48 PBH. Compared with the burn group, the injury was markedly alleviated in the experiment group, and the pulmonary capillary endothelial cells showed tighter junction.

CONCLUSIONHDL exhibits a protective effect on the lung function of rats with severe burns via reducing the expression of ICAM-1 and TNF-alpha.