Athero-inflammatory nanotherapeutics: Ferulic acid-based poly(anhydride-ester) nanoparticles attenuate foam cell formation by regulating macrophage lipogenesis and reactive oxygen species generation.

Enhanced bioactive anti-oxidant formulations are critical for treatment of inflammatory diseases, such as atherosclerosis. A hallmark of early atherosclerosis is the uptake of oxidized low density lipoprotein (oxLDL) by macrophages, which results in foam cell and plaque formation in the arterial wall. The hypolipidemic, anti-inflammatory, and antioxidative properties of polyphenol compounds make them attractive targets for treatment of atherosclerosis. However, high concentrations of antioxidants can reverse their anti-atheroprotective properties and cause oxidative stress within the artery. Here, we designed a new class of nanoparticles with anti-oxidant polymer cores and shells comprised of scavenger receptor targeting amphiphilic macromolecules (AMs). Specifically, we designed ferulic acid-based poly(anhydride-ester) nanoparticles to counteract the uptake of high levels of oxLDL and regulate reactive oxygen species generation (ROS) in human monocyte derived macrophages (HMDMs). Compared to all compositions examined, nanoparticles with core ferulic acid-based polymers linked by diglycolic acid (PFAG) showed the greatest inhibition of oxLDL uptake. At high oxLDL concentrations, the ferulic acid diacids and polymer nanoparticles displayed similar oxLDL uptake. Treatment with the PFAG nanoparticles downregulated the expression of macrophage scavenger receptors, CD-36, MSR-1, and LOX-1 by about 20-50%, one of the causal factors for the decrease in oxLDL uptake. The PFAG nanoparticle lowered ROS production by HMDMs, which is important for maintaining macrophage growth and prevention of apoptosis. Based on these results, we propose that ferulic acid-based poly(anhydride ester) nanoparticles may offer an integrative strategy for the localized passivation of the early stages of the atheroinflammatory cascade in cardiovascular disease. STATEMENT OF SIGNIFICANCE: Future development of anti-oxidant formulations for atherosclerosis applications is essential to deliver an efficacious dose while limiting localized concentrations of pro-oxidants. In this study, we illustrate the potential of degradable ferulic acid-based polymer nanoparticles to control macrophage foam cell formation by significantly reducing oxLDL uptake through downregulation of scavenger receptors, CD-36, MSR-1, and LOX-1. Another critical finding is the ability of the degradable ferulate-based polymer nanoparticles to lower macrophage reactive oxygen species (ROS) levels, a precursor to apoptosis and plaque escalation. The degradable ferulic acid-based polymer nanoparticles hold significant promise as a means to alter the treatment and progression of atherosclerosis.

Polymer brain-nanotherapeutics for multipronged inhibition of microglial α-synuclein aggregation, activation, and neurotoxicity.

Neuroinflammation, a common neuropathologic feature of neurodegenerative disorders including Parkinson disease (PD), is frequently exacerbated by microglial activation. The extracellular protein α-synuclein (ASYN), whose aggregation is characteristic of PD, remains a key therapeutic target, but the control of synuclein trafficking and aggregation within microglia has been challenging. First, we established that microglial internalization of monomeric ASYN was mediated by scavenger receptors (SR), CD36 and SRA1, and was rapidly accompanied by the formation of ASYN oligomers. Next, we designed a nanotechnology approach to regulate SR-mediated intracellular ASYN trafficking within microglia. We synthesized mucic acid-derivatized sugar-based amphiphilic molecules (AM) with optimal stereochemistry, rigidity, and charge for enhanced dual binding affinity to SRs and fabricated serum-stable nanoparticles via flash nanoprecipitation comprising hydrophobe cores and amphiphile shells. Treatment of microglia with AM nanoparticles decreased monomeric ASYN internalization and intracellular ASYN oligomer formation. We then engineered composite deactivating NPs with dual character, namely shell-based SR-binding amphiphiles, and core-based antioxidant poly (ferrulic acid), to investigate concerted inhibition of oxidative activation. In ASYN-challenged microglia treated with NPs, we observed decreased ASYN-mediated acute microglial activation and diminished microglial neurotoxicity caused by exposure to aggregated ASYN. When the composite NPs were administered in vivo within the substantia nigra of fibrillar ASYN-challenged wild type mice, there was marked attenuation of activated microglia. Overall, SR-targeting AM nanotechnology represents a novel paradigm in alleviating microglial activation in the context of synucleinopathies like PD and other neurodegenerative diseases.

Tartaric acid-based amphiphilic macromolecules with ether linkages exhibit enhanced repression of oxidized low density lipoprotein uptake.

Cardiovascular disease initiates with the atherogenic cascade of scavenger receptor- (SR-) mediated oxidized low-density lipoprotein (oxLDL) uptake. Resulting foam cell formation leads to lipid-rich lesions within arteries. We designed amphiphilic macromolecules (AMs) to inhibit these processes by competitively blocking oxLDL uptake via SRs, potentially arresting atherosclerotic development. In this study, we investigated the impact of replacing ester linkages with ether linkages in the AM hydrophobic domain. We hypothesized that ether linkages would impart flexibility for orientation to improve binding to SR binding pockets, enhancing anti-atherogenic activity. A series of tartaric acid-based AMs with varying hydrophobic chain lengths and conjugation chemistries were synthesized, characterized, and evaluated for bioactivity. 3-D conformations of AMs in aqueous conditions may have significant effects on anti-atherogenic potency and were simulated by molecular modeling. Notably, ether-linked AMs exhibited significantly higher levels of inhibition of oxLDL uptake than their corresponding ester analogues, indicating a dominant effect of linkage flexibility on pharmacological activity. The degradation stability was also enhanced for ether-linked AMs. These studies further suggested that alkyl chain length (i.e., relative hydrophobicity), conformation (i.e., orientation), and chemical stability play a critical role in modulating oxLDL uptake, and guide the design of innovative cardiovascular therapies.