Macrophage Targeted Dendrimer-Tesaglitazar Therapy for Atherosclerosis

Abstract

Background: Atherosclerosis is a leading contributor to cardiovascular disease, the number one cause of death globally. Although atherosclerosis is clearly a multicellular disease that also affects endothelial cells as well as smooth muscle cells of arteries, it is increasingly recognized as an inflammatory disease. Our goal is to determine if targeting immune cells implicated in atherosclerosis can halt plaque accumulation and resulting derangement of vascular cells in the aorta. Peroxisome proliferator activated receptors (PPARs) within macrophages present a promising therapeutic target as PPAR-α and PPAR-γ agonists have been shown to improve lipid metabolism and inhibit macrophage foam cell formation. However, due to high doses required and associated side effects, clinical translation was halted. We target anti-atherogenic pathways in immune cells using the novel treatment D-Tesa, a dendrimer conjugate of a dual PPAR-α/γ agonist, Tesaglitazar. Methods: 25-week-old, male, apolipoprotein E knockout (ApoE−/−) mice were fed high fat diet (HFD) for 16 weeks to induce atherosclerosis and randomized into two groups: 1) treatment group: D-Tesa for 6 weeks (20μg/kg twice weekly by oral gavage and 2) untreated group. HFD was continued for the duration of the study. Pulse wave velocity (PWV: Doppler), blood pressure (BP: tail cuff on trained, conscious mice), and body weight were monitored. Dendrimer mediated delivery of drug payload to plaque macrophages was studied using D-Cy5, a fluorescently labeled dendrimer, in an atherosclerotic mouse. Aortas were isolated and used for vasoreactivity studies and western blot analysis. THP-1 cell derived foam cells were used to study D-Tesa’s mechanism of action in vitro. Results: Immunofluorescence staining and confocal microscopy revealed that D-Cy5 localized in macrophages within the atherosclerotic plaque in ApoE−/− mice on HFD, indicating that the dendrimer can deliver drugs specifically into the plaque. D-Tesa slowed plaque progression, preserved endothelial function, and decreased arterial stiffness. BP was similar and unchanged between groups. D-Tesa surprisingly decreased body weight, which was the opposite effect observed from the free drug in clinical trials. Western blotting of aorta revealed that D-Tesa treated mice experienced an upregulation of PPAR-α, PPAR-γ, and ABCA1. The in vitro studies with THP-1 derived foam cells confirmed the upregulation of the cholesterol efflux pathway and anti-inflammatory benefit of D-Tesa. Conclusion: D-Tesa offers a novel therapy to ameliorate multiple damaging consequences of atherosclerosis on the cardiovascular system including improvements in plaque burden, endothelial function, arterial stiffness, and body weight in an ApoE−/− model of atherosclerosis. Excitingly, these effects were seen at 2-15 times lower doses despite continued HFD than those reported in literature with a combination of free Tesa and low-fat diet. Thus, D-Tesa offers great translational relevance because of potential reduction in negative side effects and higher patient benefit due to noted lack of compliance with dietary changes in the clinic. Further research is ongoing to evaluate sex differences, dose response, and long-term effects of this highly promising therapy. This work was supported by a NHLBI grant R01HL148112 01 (L.S.) and the Traystman Endowment (S.K.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.