SN50 attenuates alveolar hypercoagulation and fibrinolysis inhibition in acute respiratory distress syndrome mice through inhibiting NF-κB p65 translocation

Background It has been confirmed that NF-kappa B p65 signaling pathway is involved in the regulation of alveolar hypercoagulation and fibrinolysis inhibition in acute respiratory distress syndrome (ARDS). Whether SN50, a NF-kappa B cell permeable inhibitor, could attenuate alveolar hypercoagulation and fibrinolysis inhibition in ARDS remains to be elucidated. Purpose We explored the efficacy and potential mechanism of SN50 on alveolar hypercoagulation and fibrinolysis inhibition in ARDS in mice. Materials and methods Mouse ARDS was made by 50 mu l of lipopolysaccharide (LPS) (4 mg/ml) inhalation. Male BALB/c mice were intraperitoneally injected with different does of SN50 1 h before LPS inhalation. Lung tissues were collected for hematoxylin-eosin (HE) staining, wet/dry ratio. Pulmonary expressions of tissue factor (TF), plasminogen activator inhibitor-1 (PAI-1), collagen III, as well as phosphorylated p65 (p-p65), p65 in nucleus (p'-p65), I kappa B alpha and IKK alpha/beta were measured. Bronchoalveolar lavage fluid (BALF) was gathered to test the concentrations of TF, PAI-1, activated protein C (APC) and thrombinantithrombin complex (TAT). DNA binding activity of NF-kappa B p65 was also determined. Results After LPS stimulation, pulmonary edema and exudation and alveolar collapse occured. LPS also stimulated higher expressions of TF and PAI-1 in lung tissues, and higher secretions of TF, PAI-1, TAT and low level of APC in BALF. Pulmonary collagen III expression was obviously enhanced after LPS inhalation. At same time, NF-kappa B signaling pathway was activated with LPS injury, shown by higher expressions of p-p65, p'-p65, p-IKK alpha/beta, p-I kappa alpha in pulmonary tissue and higher level p65 DNA binding activity. SN50 dose-dependently inhibited TF, PAI-1 and collagen IIIexpressions, and decreased TF, PAI-1, TAT but increased APC in BALF. SN50 treatment attenuated pulmonary edema, exudation and reduced lung tissue damage as well. SN50 application significantly reduced p'-p65 expression and weakened p65 DNA binding activity, but expressions of p-p65, p-IKK alpha/beta, p-I kappa alpha in cytoplasm of pulmonary tissue were not affected. Conclusions SN 50 attenuates alveolar hypercoagulation and fibrinolysis inhibition in ARDS via inhibition of NF-kappa B p65 translocation. Our data demonstrates that NF-kappa B p65 pathway is a viable new therapeutic target for ARDS treatment.