Site-Targeting Nanotherapeutic for Suppression of Vascular Inflammation
The goal of this research was to develop a site-targeting nanotherapeutic drug delivery platform for suppression of chronic vascular inflammation and regression associated with debilitating conditions such as pulmonary arterial hypertension (PAH) and diabetic retinopathy (DR). Importantly, loss of endothelium-derived nitric oxide (NO), an endogenous anti-inflammatory and pro-vasculogenic factor that prevents leukocyte-endothelial cell (EC) adhesion and capillary regression, is strongly implicated in chronic inflammation associated with these conditions. Thus, restoring NO levels represents a viable approach for anti-inflammatory therapies. Nitroglycerin (NTG) markedly enhances nitric oxide (NO) bioavailability. However, its ability to mimic the anti-inflammatory and pro-vasculogenic properties of NO remains unknown. Here, the overarching goal was to examine whether (1) NTG can suppress vascular inflammation and regression, (2) a nanotechnological drug delivery approach can be leveraged to simultaneously amplify its anti-inflammatory effects and ameliorate adverse effects associated with conventional high-dose NTG administration, and finally (3) NTG nanoformulation can be modified to selectively deliver NTG to inflamed
ICAM-1-expressing vessels. My findings reveal that NTG significantly inhibits monocyte adhesion to inflamed ECs and prevents EC capillary regression in vitro through an increase in endothelial NO and decrease in endothelial ICAM-1 clustering. More importantly, nanoliposomal NTG (NTG-NL) produced an approximately 70-fold increase in NTG drug efficacy when compared with 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, whole ICAM-1 IgG and non-immunogenic anti-ICAM-1 scFv fragment were tethered to the surface of NTG-NL. As
a proof-of-concept study whole ICAM-1 IgG-modified NLs demonstrated preferential targeting to inflamed vessel, in vivo. Importantly, however, the translational potential of these NLs lies with the non-immunogenic scFv fragment. The following in vitro studies reveal that NTG-NL modified with anti-ICAM-1 scFv exhibits 6-fold greater binding to inflamed (ICAM-1-expressing) ECs than to normal ECs and achieves superior anti-inflammatory effects. Thus, these findings provide the rationale to examine this novel site-targeting NTG nanotherapeutic as a potentially superior therapy for various vascular inflammation-mediated conditions. Addressing these critical issues related to potential NTG-based therapy forms the central theme of the following dissertation.