Abstract 456: Myxoma Viral Proteins, M-T7, Serp-1 and Serp-2, Alter Human Monocyte Gene Expression in Vitro

Abstract

Introduction: Atherosclerosis is characterized by ongoing chronic inflammation, cell damage, apoptosis and scar formation all of which can initiate plaque growth and arterial occlusion. These proteases are controlled by serine protease inhibitors, or serpins, which regulate apoptotic and inflammatory pathways. Complex DNA viruses, such as myxomavirus, have developed highly active immune defense systems which include viral serpins that inhibit inflammation at picogram to microgram doses. Serp-1, a secreted serpin, significantly reduces inflammatory cell activation, invasion and plaque growth in animal models and is in clinical trials. One cross-class serpin, Serp-2, has demonstrated anti-inflammatory and anti-apoptotic effects in a variety of animal models. M-T7, a secreted non-serpin chemokine binding protein, reduces vascular plaque and inflammation. Previous microarray experiments detected no significant changes with viral protein treatment alone, underscoring a need for activated cells. This study assesses the effects of viral proteins with anti-inflammatory and anti-atherogenic activity on atherosclerosis-related gene expression changes in activated human monocytes. Methods: Triplicate samples of THP-1 human monocytic cells were incubated with saline, 10μM camptothecin alone or in combination with individual serpins (500ng/million cells) for 30 mins at 37°C. Real-time RT-PCR analysis was performed. Results: At 30m, the viral proteins elicited significant expression changes in THP-1 monocytes for genes in purported atherosclerotic pathways. CCL2 was upregulated by Serp-1 (P = 0.0031). PDGFB was significantly increased by Serp-1 (P = 0.0203) and to a lesser extent by Serp-2 and M-T7. M-T7 significantly upregulated L-Selectin (P = 0.0023). Serp-2 significantly downregulated Lipoprotein(a) (P =0.0500). Conclusion: Significant expression changes were detected in human monocytic cells after treatment with three unique anti-inflammatory viral proteins. Differential regulation of genes such as PDGFB underscores the multifaceted approach viral proteins take toward controlling inflammation. Altering atherogenic responses in monocytic cells represents a new potential therapeutic target for inflammatory vascular diseases.