Abstract 14296: Site-targeting Nitroglycerin Nanotherapeutic for Local Immunosuppression Without Induction of Tolerance

Abstract

Nitroglycerin (NTG) markedly enhances nitric oxide (NO) bioavailability. However, its ability to mimic the anti-inflammatory properties of NO remains unknown. Here, we examined whether NTG can suppress endothelial cell (EC) activation during inflammation and developed NTG nanoformulation to simultaneously amplify its anti-inflammatory effects and ameliorate adverse effects associated with high-dose NTG administration. Our findings reveal that NTG significantly inhibits human monocyte adhesion to NO-deficient human microvascular ECs in vitro (EC50 = 0.64 uM) through an increase in endothelial NO and decrease in endothelial ICAM-1 clustering, as determined by NO analyzer, microfluorimetry, and immunofluorescence staining. Nanoliposomal NTG (NTG-NL) was formulated by encapsulating NTG within unilamelar lipid nanoparticles that were ~150 nm in diameter and readily uptaken by ECs, as determined by dynamic light scattering and quantitative fluorescence microscopy, respectively. More importantly, NTG-NL produced an approximately two orders of magnitude greater anti-inflammatory effect than free NTG while preventing excessive mitochondrial superoxide production and loss of arterial vasorelaxation associated with high NTG doses. Finally, to facilitate targeting of NTG-NL to inflamed ICAM-1-expressing vessels, we have tethered a non-immunogenic fragment of ICAM-1 antibody to the surface of NTG-NL. Our preliminary in vitro studies show that NTG-NL modified with anti-ICAM-1 fragment exhibits 6-fold greater binding to inflamed (ICAM-1-expressing) ECs than to normal ECs. Thus, by identifying the superior therapeutic effects of NTG nanoformulation and conferring potent site-targeting capability to it, this study provides the rationale for detailed investigation of NTG nanotherapeutic as a potentially superior anti-inflammatory therapy.