Abstract 211: Modulating Inflammation In Atherosclerosis Through Engineered Anti-Inflammatory Cytokine Delivery

Abstract

Introduction: Atherosclerosis is a chronic inflammatory disease resulting from the accumulation of low-density lipoprotein (LDL) in arterial walls. The anti-inflammatory cytokine IL-10 has been implicated in atherosclerosis with higher levels correlating with reduced lesion sizes. However, cytokine therapies have not translated well to the clinic partially due their rapid clearance and pleiotropic nature. Methods: Here, we use protein engineering approaches to target IL-10 to LDL and subsequently to atherosclerotic plaques. We fuse IL-10 to an antibody fragment against oxidized LDL and show by surface plasmon resonance that it binds to both native LDL and oxidized LDL while retaining its ability to phosphorylate STAT3 in RAW 264.7 macrophage/monocyte-like cells. We then use flow cytometry to evaluate immune cell populations in the aortas of apolipoprotein E -/- mice on a high fat diet after 4 weekly injections. Results: Mice treated with our targeted IL-10 fusion protein had significantly reduced numbers of total leukocytes in the aorta compared to nontreated mice after 12 weeks on a high fat diet (n=6, Figure 1a). The number of macrophage/monocyte cells which may contribute to foam cell populations in the plaque was similarly reduced (Figure 1b). No differences in immune cell populations were observed in the spleen, indicative of the localized treatment effect. Furthermore, neither native IL-10 nor IL-10 fused to an antibody fragment of irrelevant specificity (non-targeted IL-10) showed any reduction of immune cell infiltration in the aorta. These findings were reproduced in apolipoprotein E -/- mice fed a high fat diet for 9 weeks (n=8) to show that aortic immune cell infiltration is also reduced at earlier stages in atherosclerosis progression. Conclusion: Engineered cytokines that specifically target LDL effectively provide local immunosuppression and show promise in the prevention and treatment of atherosclerosis.$