Intracerebral fate of organic and inorganic nanoparticles is dependent on microglial extracellular vesicle function.

Nanoparticles (NPs) represent an important advance for delivering diagnostic and therapeutic agents across the blood-brain barrier. However, NP clearance is critical for safety and therapeutic applicability. Here we report on a study of the clearance of model organic and inorganic NPs from the brain. We find that microglial extracellular vesicles (EVs) play a crucial role in the clearance of inorganic and organic NPs from the brain. Inorganic NPs, unlike organic NPs, perturb the biogenesis of microglial EVs through the inhibition of ERK1/2 signalling. This increases the accumulation of inorganic NPs in microglia, hindering their elimination via the paravascular route. We also demonstrate that stimulating the release of microglial EVs by an ERK1/2 activator increased the paravascular glymphatic pathway-mediated brain clearance of inorganic NPs. These findings highlight the modulatory role of microglial EVs on the distinct patterns of the clearance of organic and inorganic NPs from the brain and provide a strategy for modulating the intracerebral fate of NPs.

Nanopolyphenol rejuvenates microglial surveillance of multiple misfolded proteins through metabolic reprogramming.

Microglial surveillance plays an essential role in clearing misfolded proteins such as amyloid-beta, tau, and α-synuclein aggregates in neurodegenerative diseases. However, due to the complex structure and ambiguous pathogenic species of the misfolded proteins, a universal approach to remove the misfolded proteins remains unavailable. Here, we found that a polyphenol, α-mangostin, reprogrammed metabolism in the disease-associated microglia through shifting glycolysis to oxidative phosphorylation, which holistically rejuvenated microglial surveillance capacity to enhance microglial phagocytosis and autophagy-mediated degradation of multiple misfolded proteins. Nanoformulation of α-mangostin efficiently delivered α-mangostin to microglia, relieved the reactive status and rejuvenated the misfolded-proteins clearance capacity of microglia, which thus impressively relieved the neuropathological changes in both Alzheimer's disease and Parkinson's disease model mice. These findings provide direct evidences for the concept of rejuvenating microglial surveillance of multiple misfolded proteins through metabolic reprogramming, and demonstrate nanoformulated α-mangostin as a potential and universal therapy against neurodegenerative diseases.

The effect of drug loading and multiple administration on the protein corona formation and brain delivery property of PEG-PLA nanoparticles.

The presence of protein corona on the surface of nanoparticles modulates their physiological interactions such as cellular association and targeting property. It has been shown that α-mangostin (αM)-loaded poly(ethylene glycol)-poly(l-lactide) (PEG-PLA) nanoparticles (NP-αM) specifically increased low density lipoprotein receptor (LDLR) expression in microglia and improved clearance of amyloid beta (Aß) after multiple administration. However, how do the nanoparticles cross the blood‒brain barrier and access microglia remain unknown. Here, we studied the brain delivery property of PEG-PLA nanoparticles under different conditions, finding that the nanoparticles exhibited higher brain transport efficiency and microglia uptake efficiency after αM loading and multiple administration. To reveal the mechanism, we performed proteomic analysis to characterize the composition of protein corona formed under various conditions, finding that both drug loading and multiple dosing affect the composition of protein corona and subsequently influence the cellular uptake of nanoparticles in b.End3 and BV-2 cells. Complement proteins, immunoglobulins, RAB5A and CD36 were found to be enriched in the corona and associated with the process of nanoparticles uptake. Collectively, we bring a mechanistic understanding about the modulator role of protein corona on targeted drug delivery, and provide theoretical basis for engineering brain or microglia-specific targeted delivery system.

Multiclass analysis of 23 veterinary drugs in milk by ultraperformance liquid chromatography-electrospray tandem mass spectrometry.

An ultraperformance liquid chromatography-electrospray tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous detection and confirmation of 23 veterinary (multiclass) drugs in milk was developed and validated. The analytes were extracted by acetonitrile, evaporated and injected into the UPLC-MS/MS system on a Waters UPLC HSS T3 column in gradient mode. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring (MRM) of two ion transitions per compound to provide a high degree of specificity. Results showed good repeatability, and recoveries for the 12 macrolide, 7 ß-lactam and 2 lincosamide antibiotics and 2 other veterinary drugs (morantel, orbifloxacin) used in milk averaged 51.8-139.0%, 51.5-100.6%, 82.4-102.5% and 87.5-99.4%, respectively. The coefficients of variation (C.V.) of the recoveries were less than 15% for intraday and interday precisions. The limits of quantification (LOQs) were all lower than 5 ng/ml. This method was applied to 17 fresh milk samples and only lincomycin was found in milk samples under allowable levels. Overall, this method is a suitable and rapid tool to confirm the presence of 23 veterinary drug residues in milk.