Abstract 31: In Vivo Targeting of Inflammation Associated Myeloid-Related Protein 8/14 via Gadolinium Immunonanoparticles

Background: Myeloid-related protein 8/14 complex (Mrp-8/14) is a highly expressed extracellularly secreted protein, implicated in atherosclerosis. In this study, we evaluated the feasibility of targeting Mrp in-vivo through synthetic immuno-nanoprobes. Methods and Results: Anti-Mrp-14 and nonspecific IgG-conjugated gadolinium nanoprobes (aMrp-NP and IgG-NP respectively) were synthesized and characterized. Apolipoprotein E deficient (ApoE-/-) or ApoE-/-/Mrp14-/-(DKO) animals were fed a high-fat diet for 20 weeks followed by assessment of in-vivo pharmacokinetics and vascular targeting via magnetic resonance imaging (MRI). Bone marrow-derived myeloid progenitor cells were isolated from both ApoE -/- and DKO mice and differentiated to macrophages (BMDM). BMDM were treated with LPS, with or without Mrp8, Mrp14, or Mrp8/14 and conditioned media (CM) was collected and used for in-vitro studies. Mrp-activated cells secreted significant amounts of pro-inflammatory cytokines which was abolished by pretreatment with aMrp-NP. We show in vitro that aMrp-NP binds endothelial cells previously treated with CM containing Mrp8/14. MRI following intravenous delivery of aMrp-NP revealed prolonged and substantial delineation of plaque in ApoE -/- but not DKO animals with favorable pharmacokinetics (Figure 1). Flow-cytometric analysis of aortic digesta revealed aMrp-NP presence in Ly-6G+, CD11b+, CD11c+ and CD31+ cells in ApoE -/- but not in DKO animals. Conclusion: Targeted imaging with aMrp-NP demonstrates enhancement of plaque with binding to inflammatory cells and reduction in inflammation. This strategy has promise as a theranostic approach for atherosclerosis