Homocysteine Elicits an Inflammatory Profile in Murine Macrophages Through an EMMPRIN Mediated Pathway

Introduction: Macrophages are known to differentiate between two distinct phenotypic subsets: M1 and M2. The M1 phenotype elicits a pro-inflammatory profile while M2 macrophages are categorized as being anti-inflammatory. Hyperhomocysteinemia (HHcy) is associated with many inflammatory diseases such as obesity and atherosclerosis. It is known that HHcy increases specific macrophage secretory factors, such as MCP-1 and MMP-9. However, the direct effect of HHcy on macrophage phenotype is largely unexplored. We hypothesize that HHcy causes macrophages to shift into a more inflammatory phenotype or M1. Methods: We utilized 2 murine macrophage cell lines: Raw 264.7 and J774A.1 cells. These cells were treated with 500 and 100 µM homocysteine, respectively, for 24 hours. Methods employed are Western Blot, ICC, FACS and PCR. Results: In Raw 264.7 cells, 24 hour treatment with 500 μM Hcy resulted in a 2.25 fold increase in CD40 protein expression: a cell surface marker on M1 macrophages. ICC confirms this increase...