The Regulation Of Lipopolysaccharide-induced MMP-9 Expression By Norepinephrine And The Mechanism Research

BackgroundAtherosclerosis is a chronic inflammatory disease, unstable atherosclerosis plague leads to thrombosis and acute coronary syndrome. Matrix metalloproteinase-9 (MMP-9) is capable of degrading the extracellular matrix (ECM).Previous reports have demonstrated that MMP-9 is involved in the atherosclerosis plague unstability. Until now, we know that Lipopolysaccharide (LPS) and Norepinephrine (NE) are associated with the pathological process of atherosclerosis. But the combined effect of LPS and NE is not very clear. We intend to investigate the combined effect of LPS and NE, which are two risk factors in atherosclerosis, on MMP-9 expression in human monocytes and the mechanism involved in the process.MethodsMonocytes are involved in the development of atherosclerosis plague. In our research, THP-1 cells and macrophages which were derived from THP-1 were cultured and treated with LPS and NE.The main methords are as follows:1.MMPs and TIMP-1 gene expression were detected by Real time PCR in myocytes.2. MMP-9 and TIMP-1 expression in the cell supernatants were measured by Elisa.3. MMP-9 activity was measured by gelatin Zymography in THP-1 cells and macrophages which were derived from THP-1 cells.4. Pathway-related proteins in MMP-9 expression by NE/LPS were detected by western blot.5. The adrenoceptor antagonist,MAPKs inhibitors and C-FOS siRNA were used to clarify the mechanism.Results1. NE enhances LPS-induced MMP-9 and TIMP-1 mRNA and protein expression.2. NE enhances LPS-induced MMP-9 activity in THP-1 cells and macrophages.3. Beta-adrenoceptor antagonist Propranolol reversed NE/LPS induced MMP-9 expression, while alpha adrenoceptor antagonist Phentolamine had no effect.4. NE enhances LPS-induced extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinase (JNK) phosphorylation. ERK and JNK inhibitors reverse MMP-9 expression and activity by LPS and NE. C-FOS knock down partly reversed MMP-9 activity evoked by LPS/NE.5. NE enhances LPS-induced C-JUN phosphorylation.Conclusions1. NE enhances LPS-induced MMP-9 expression and activity in THP-1 cells and macrophages.2. Through beta-adrenoceptor activation, NE enhances LPS-induced MMP-9 expression.3. NE enhances LPS-induced MMP-9 expression through ERK/JNK pathway.4. Components of AP-1 transcription factor (C-FOS and C-JUN) play an important role in the regulation of MMP-9 induced by NE/LPS.