The Study Of Mechanism Of High Mobility Group Box Protein1on Pulmonary Vascular Remodeling In Rats With Acute Lung Injury Induced By Endotoxin

Objective:To investigate the mechanism of high mobility group box protein1on the pulmonary vascular remodeling in rats with acute lung injury by endotoxin,providing new theory to the clinical thrapy for endotoxin-induced acute lung injury.Materials and methods:Male wistar rats,(160-220g), were randomly divided into3groups, i.e., control (saline)-treated group (n=10), anti-HMGB1+LPS-treated group (n=10), LPS-treated group (n=10). In the LPS-treated group rat received a vena caudalis injection of LPS (1mg/kg) by micro pump in a constant speed.In the control group, animals received a gavage of saline and served as controls. In the anti-HMGB1+LPS treated group, antibodies(2mg/kg) was given to rat by a vena caudalis injection at12h/24h/48h after the injection of LPS according to the LPS-treated group rat.Rat were sacrificed at least72h after the first administration. Pulmonary histopathological changes were observated by Hematoxylin and Eosin staining; immunohistochemistry method observe the expression of PCNA、bax、 bcl-2of the pulmonary smooth muscle cell; Levels of Bax, bcl-2, and HMGB1mRNA in lung tissue were determined by using Semi-quantitative RT-PCR method; western blots showed the expression of total hmgb1、bax、bcl-2in lung tissues in different groups.Results:(1) Histopathologic changes:L group:the pulmonary arteriole wall thickened, less lumen space and obvious smooth muscle cells infiltration into the medial memebrane,compared with C group and H group(P<0.05);there is no significantly differences between C and H group(P>0.05)。 (2)Immunohistochemistry:the expression of PCNA, bax, bcl-2in the memebrane of pulmonary arterioles can be observed,the brown blot is the positive results.(3)The expression of PCNA in the memebrane of pulmonary arterioles was significantly increased compared with the control and anti-HMGB1groups (P<0.05).(4) HMGB1and bcl-2mRNA levels were up-regulated in LPS group, the result is statistically significant for HMGB1and bcl-2mRNA(P<0.05vs. control group and anti-HMGB1group).On the contrary, the level of bax mRNA expression was significantly down-regulated (P<0.05vs. control group and anti-HMGB1group).(5) Representative western blots showed the expression of HMGB1protein and bcl-2protein was markedly increased in L group (P<0.05). The expression of bax protein was significantly suppressed in L group, compared with C group and H group(P<0.05).Conclusion:1. Pulmonary vascular remodeling occurred in the process of LPS-induced acute lung injury2. Downregulating the Bax gene expression and upregulating the Bcl-2gene expression by HMGB1in vivo further promoted the pulmonary artery configuration remodeling induced by exceptionally proliferation of PASMC after the acute lung damage by the endotoxin in rats.3. HMGB1neutralizing antibody suppressed the pulmonary artery remodelling induced by proliferation of PASMC after the endotoxin-induced acute lung damage rats by neutralizing HMGB1.