Background Prior studies show apolipoprotein A1 (apoA1) recovered from human atherosclerotic lesions is highly oxidized. Ex vivo oxidation of apoA1 or high density lipoprotein (HDL) cross-links apoA1 and impairs lipid binding, cholesterol efflux and lecithin cholesterol acyltransferase (LCAT) activities of the lipoprotein. Remarkably, no studies to date directly quantify either the function or HDL particle distribution of apoA1 recovered from the human artery wall. Methods and Results A monoclonal antibody (mAb 10G1.5) was developed that equally recognizes lipid-free and HDL-associated apoA1 in both native and oxidized forms. Examination of homogenates of atherosclerotic plaque-laden aorta showed >100-fold enrichment of apoA1 compared to normal aorta (P<0.001). Surprisingly, buoyant density fractionation revealed only a minority (<3% of total) of apoA1 recovered from either lesions or normal aorta resides within an HDL-like particle (1.063 ≤ d ≤ 1.21). In contrast, the majority (>90%) of apoA1 within aortic tissue (normal and lesions) was recovered within the lipoprotein-depleted fraction (d>1.21). Moreover, both lesion and normal artery wall apoA1 is highly cross-linked (50–70% of total), and functional characterization of apoA1 quantitatively recovered from aorta using mAb 10G1.5 showed ~80% lower cholesterol efflux activity and ~90% lower LCAT activity relative to circulating apoA1. Conclusions The function and distribution of apoA1 in human aorta are quite distinct from those found in plasma. The lipoprotein is markedly enriched within atherosclerotic-plaque, predominantly lipid-poor, not associated with HDL, extensively oxidatively cross-linked, and functionally impaired.

Liver X receptor (LXR) signaling pathways regulate lipid metabolism and inflammation, which has generated widespread interest in developing synthetic LXR agonists as potential therapeutics for the management of atherosclerosis. In this study, we demonstrate that nanoparticles (NPs) containing the synthetic LXR agonist GW3965 (NP-LXR) exert anti-inflammatory effects and inhibit the development of atherosclerosis without causing hepatic steatosis. These NPs were engineered through self-assembly of a biodegradable diblock poly(lactide-co-glycolide)-b-poly(ethylene glycol) (PLGA-b-PEG) copolymer. NP-LXR was significantly more effective than free GW3965 at inducing LXR target gene expression and suppressing inflammatory factors in macrophages in vitro and in vivo. Addtionally, the NPs elicited negligible lipogenic gene stimulation in the liver. Using the Ldlr−/− mouse model of atherosclerosis, we saw abundant co-localization of fluorescently labeled NPs within plaque macrophages following systemic administration. Notably, six intravenous injections of NP-LXR over two weeks markedly reduced the CD68-positive cell (macrophage) content of plaques (by 50%) without increasing total cholesterol or triglycerides in the liver and plasma. Together, these findings identify GW3965-encapsulated PLGA-b-PEG NPs as a promising nanotherapeutic approach to combat atherosclerosis, providing the benefits of LXR agonists without their adverse effects on hepatic and plasma lipid metabolism.

Liver X receptors (LXRs) attenuate inflammation by modulating the expression of key inflammatory genes, making LXRs and their ligands particularly attractive candidates for therapeutic intervention in cardiovascular, metabolic, and/or inflammatory diseases. In this study, we demonstrate enhanced proresolving activity of nanoparticles (NPs) containing the synthetic LXR agonist GW3965 (LXR-NPs), developed from a combinatorial library of more than 70 formulations with variations in critical physicochemical parameters. The library of LXR-NPs was engineered via self-assembly of biodegradable poly(lactide)- and poly(lactide-co-glycolide)-based polymers. In vitro studies on peritoneal macrophages confirmed that LXR-NPs were significantly more effective than the free agonist (GW3965) at downregulating pro-inflammatory mediators (MCP-1 and TNFα), as well as inducing the expression of LXR target genes (ABCA1 and SREBP1c). Through a zymosan-induced acute peritonitis in vivo model, LXR-NPs were found to be more efficient than free LXR agonist at limiting the recruitment of polymononuclear neutrophils (50% vs. 17%) and at decreasing the resolution interval up to 4 h. In addition, treatment with LXR-NPs significantly suppressed gene expression and secretion of pro-inflammatory factors MCP-1 and TNFα in peritoneal macrophages when compared to LXR agonist alone. Furthermore, the LXR-NPs suppressed secretion of these pro-inflammatory factors by monocytes and macrophages more efficiently than the commercial drug dexamethasone. Overall, these findings demonstrate that LXR-NPs are capable of promoting resolution of inflammation and highlight the prospect of LXR-based nanotherapeutics for inflammatory diseases.

Influenza is one of the most common causes of human morbidity and mortality that is preventable by vaccination. Immunization with available vaccines provides incomplete protection against illness caused by influenza virus, especially in high-risk groups such as the elderly and young children. Thus, more efficacious vaccines are needed for the entire population, and all the more so for high-risk groups. One way to improve immune responses and protection is to formulate the vaccine with antigen carriers and/or adjuvants, which can play an important role in improving immune responses and delivery to antigen-presenting cells, especially for a vaccine like influenza that is based on protein antigens usually administered without a carrier or adjuvant. In this review, the authors present an overview of available vaccines, focusing on research and development of new adjuvants used in influenza vaccines, as well as adjuvanted influenza vaccines aimed to improve immune responses, protection and breadth of coverage for influenza.

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