RESUMO
OBJECTIVE: To investigate the expression of scavenger receptor class A (SR-A) in lung tissue and alveolar macrophage (AM) in mice with acute lung injury (ALI) induced by lipopolysaccharide (LPS). METHODS: The model of ALI was reproduced by intraperitoneal (ip) injection of LPS (5 mg/kg), and the expression of SR-A was observed in lung tissue and AM, and the expression and distribution of J774 A.1 were also studied by using mouse macrophage line. RESULTS: Partial pressure of oxygen in artery (PaO(2)) of lung tissue in LPS groups was significantly lower while wet/dry weight (W/D) ratio was higher than those in normal saline control group (both P<0.01). SR-A was widely expressed in murine lung, including AM, pulmonary vascular endothelial cells, vascular smooth muscle cells, lung epithelial cells and polymorphonuclear neutrophils. Immunohistochemical staining showed that, during the course of development of ALI in mice, the expression of SR-A was gradually down-regulated with the elapse of time after ip injection of LPS, The same result was seen in the isolated AM, and especially marked in group 4 hours and group 8 hours. In vitro, the expression of SR-A on J774 A.1 cells decreased was also down-regulated when treated with LPS. CONCLUSION: SR-A was widely expressed in murine lung. During the course of ALI, the expression of SR-A in the murine lung and AM is down-regulated, which may be induced by LPS.
