This thesis focuses on using liposomes in two different treatment strategies; vaccination (or immunotherapy) and delivery of a small molecule, and in two different disease models; cancer and... Show moreThis thesis focuses on using liposomes in two different treatment strategies; vaccination (or immunotherapy) and delivery of a small molecule, and in two different disease models; cancer and atherosclerosis. For each of these treatment strategies, the liposomal formulation was tailored to obtain the desired therapeutic effect. Chapter 2 reviews some of the most important physicochemical properties (size, shape, and rigidity) that determine the immunological effects of liposomes and other nanoparticles. In chapter 3 we present a detailed study on the effect of the rigidity of anionic liposomes, as measured by atomic force microscopy, on antigen-specific regulatory T-cell (Treg) responses. In chapter 4, we show that our optimized anionic liposomes can induce potent antigen-specific Treg responses, and can be used to delay atherosclerosis progression in a mouse model. Chapter 5 also focuses on liposomal treatment of atherosclerosis, but here targeted liposomes were prepared to successfully deliver a small molecule to foam cells in atherosclerotic plaques. In Chapter 6, we used cationic liposomes in combination with an adjuvant for cancer immunotherapy in mice. Finally, we summarize the overall findings in chapter 7 and discuss perspectives of using liposomes for vaccination and targeted drug delivery. Show less
Atherosclerosis is characterized by the retention of lipids in foam cells in the arterial intima. The liver X receptor (LXR) agonist GW3965 is a promising therapeutic compound, since it induces... Show moreAtherosclerosis is characterized by the retention of lipids in foam cells in the arterial intima. The liver X receptor (LXR) agonist GW3965 is a promising therapeutic compound, since it induces reverse cholesterol transport in foam cells. However, hepatic LXR activation increases plasma and liver lipid levels, inhibiting its clinical development. Herein, a formulation that specifically enhances GW3965 deposition in the atherosclerotic lesion is aimed to be developed. GW3965 is encapsulated in liposomes functionalized with the cyclic peptide Lyp-1 (CGNKRTRGC), which binds the p32 receptor expressed on foam cells. These liposomes show preferential uptake by foam cells in vitro and higher accumulation in atherosclerotic plaques in mice compared to non-targeted liposomes as determined by in vivo imaging. Flow cytometry analysis of plaques reveals increased retention of Lyp-1 liposomes in atherosclerotic plaque macrophages compared to controls (p < 0.05). Long term treatment of established plaques in LDLR -/- mice with GW3965-containing Lyp-1 liposomes significantly reduces plaque macrophage content by 50% (p < 0.01). Importantly, GW3965-containing Lyp-1 liposomes do not increase plasma or hepatic lipid content. Thus, GW3965-containing Lyp-1 liposomes successfully target the atherosclerotic macrophages allowing plaque stabilization without commonly observed side effects of LXR agonists. Show less
