In Vivo Targeting of Inflammation-Associated Myeloid-Related Protein 8/14 Via Gadolinium Immunonanoparticles
Objective—Myeloid-related protein (Mrp) 8/14 complex (is a highly expressed extra cellularly 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-) were synthesized and characterized. Pharmacokinetics and vascular targeting via MRI of the formulations were assessed in vivo in high fat-fed apolipoprotein E deficient (ApoE−/−), ApoE−/−/Mrp14−/− (double knockout) and chow-fed wild-type (C57BL/6) mice were. Bone marrow-derived myeloid progenitor cells were isolated from both ApoE−/− and double knockout mice and differentiated to macrophages and were treated with LPS, with or without Mrp8, Mrp14, or Mrp8/14, and conditioned media was collected and used for in vitro studies. Mrp-activated cells secreted significant amounts of proinflammatory cytokines, which were abolished by pretreatment with aMrp-NP. We show in vitro that aMrp-NP binds endothelial cells previously treated with conditioned media containing Mrp8/14. MRI following intravenous delivery of aMrp-NP revealed prolonged and substantial delineation of plaque in ApoE−/− but not double knockout or wild-type animals. Nonspecific IgG-conjugated gadolinium nanoprobe-injected animals in all groups did not show vessel wall enhancement. Flow-cytometric analysis of aortic digesta revealed aMrp-NP presence in Ly-6G+, CD11b+, CD11c+, and CD31+ cells in ApoE−/− but not in double knockout 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.
- Received December 20, 2011.
- Accepted January 18, 2012.
- © 2012 American Heart Association, Inc.