Abstract 17355: Anti-Inflammatory Nanotherapy Alters Immune Cell Composition and Reduces Lesion Area of Atherosclerotic Plaques in Ldlr-/- Mice

Abstract

Introduction: Atherosclerosis is a multi-stage disorder with an inflammatory immune component. We hypothesized that the targeted delivery of an anti-inflammatory small molecule to macrophages could modulate immune cells in the plaque and potentially reduce plaque progression. We employed celastrol as an inhibitor of NF-kB and used poly(ethylene glycol)-block-poly(propylene sulfide) (PEG-bl-PPS) polymeric micelles (MCs) for controlled delivery. Methods: PEG-bl-PPS polymer was formulated into nanocarriers at a concentration of 15 mg/mL in 1xPBS, with or without 100 ng of celastrol (Cel-MC or Blank MC). Ldlr-/- mice were fed a high fat diet for 3 months prior to the beginning of nanocarrier treatment. 100 μL of each MC formulation was administered to mice via tail vein injection once per week for 12 weeks. Results: Cel-MC inhibited NF-kB at lower concentrations compared to free celastrol (Fig. 1a) . In vivo , Cel-MCs significantly decreased neutrophils and NK cells in the aortas of atherosclerotic mice compared to blank MC controls (Fig. 1b) . Cel-MCs reduced the plaque lesion area, as determined by Oil Red O staining of aorta histology sections (Fig. 1c) . Figure 1. Cel-MC treatment of atherosclerosis. (a) NF-kB inhibition and cell viability using RAW Blue cells, error bars = S.D., n = 4. (b) Heatmap of percent change in cell populations based on flow analysis of ldlr-/- mice after 12 weeks of Cel-MC treatment, compared to blank MC treatment, n=6/4 respectively. (c) Oil Red O staining fluorescence area of aorta histology slides, n=4 mice, 3-4 sections per mouse. P-value determined using Welch’s t test. Conclusions: Cel-MC reduced NF-kB signaling in vitro and reduced immune cells in the aorta in vivo. The treatment course was well-tolerated by the mice and resulted in a significant reduction in plaque lesion area. These results demonstrate both the utility of targeted modulation of immune cells contributing to vascular inflammation.