A dual-targeted multifunctional nanoformulation for potential prevention and therapy of Alzheimer's disease

Mechanistic insights and emerging therapeutic stratagems for Alzheimer's disease

Alzheimer's disease (AD), a multi-factorial neurodegenerative disorder has affected over 30 million individuals globally and these numbers are expected to increase in the coming decades. Current therapeutic interventions are largely ineffective as they focus on a single target. Development of an effective drug therapy requires a deep understanding of the various factors influencing the onset and progression of the disease. Aging and genetic factors exert a major influence on the development of AD. Other factors like post-viral infections, iron overload, gut dysbiosis, and vascular dysfunction also exacerbate the onset and progression of AD. Further, post-translational modifications in tau, DRP1, CREB, and p65 proteins increase the disease severity through triggering mitochondrial dysfunction, synaptic loss, and differential interaction of amyloid beta with different receptors leading to impaired intracellular signalling. With advancements in neuroscience tools, new inter-relations that aggravate AD are being discovered including pre-existing diseases and exposure to other pathogens. Simultaneously, new therapeutic strategies involving modulation of gene expression through targeted delivery or modulation with light, harnessing the immune response to promote clearance of amyloid deposits, introduction of stem cells and extracellular vesicles to replace the destroyed neurons, exploring new therapeutic molecules from plant, marine and biological sources delivered in the free state or through nanoparticles and use of non-pharmacological interventions like music, transcranial stimulation and yoga. Polypharmacology approaches involving combination of therapeutic agents are also under active investigation for superior therapeutic outcomes. This review elaborates on various disease-causing factors, their underlying mechanisms, the inter-play between different disease-causing players, and emerging therapeutic options including those under clinical trials, for treatment of AD. The challenges involved in AD therapy and the way forward have also been discussed.

mTOR-Mediated Immunometabolic Reprogramming Nanomodulators Enable Sensitive Switching of Energy Deprivation-Induced Microglial Polarization for Alzheimer's Disease Management

Metabolic reprogramming that senses brain homeostasis imbalances is necessary to drive detrimental microglial polarization, and specific targeting of this process contributes to the flexible control of pathological inflammatory responses in Alzheimer's disease (AD), displaying distinctive therapeutic benefits. Herein, glutathione-functionalized gold nanocages loaded with the immunosuppressant fingolimod hydrochloride are developed as brain-targeted and microglia-located immunometabolic reprogramming nanomodulators (GAF NPs) for AD management. By virtue of glutathione-mediated transport properties, this nanomodulator can cross the blood-brain barrier and localize to microglia in AD lesions. Through blocking Akt/mTOR/HIF-1α signaling pathways, GAF NPs not only promote the dominated metabolic shift from glycolysis to oxidative phosphorylation under immune activation but also inhibit transporter-mediated glucose overconsumption by microglia. Correlation analysis based on real-time bioenergetic assessment and 18F-labeled fluorodeoxyglucose (FDG) PET reveals that brain glucose utilization and metabolism restored by GAF NP treatment can serve as a sensitive and effective indicator for microglial M1 to M2 polarization switching, ultimately alleviating neuroinflammation and its derived neurodegeneration as well as ameliorating cognitive decline in AD mice. This work highlights a potential nanomedicine aimed at modifying mTOR-mediated immunometabolic reprogramming to halt energy deprivation-induced AD progression.

Microfluidic fabrication of size-controlled nanocarriers with improved stability and biocompatibility for astaxanthin delivery

Improving the stability of astaxanthin (AST) is a vital way to enhance its oral bioavailability. In this study, a microfluidic strategy for the preparation of astaxanthin nano-encapsulation system was proposed. Thanks to the precise control of microfluidic and the rapid preparation ability of the Mannich reaction, the resulting astaxanthin nano-encapsulation system (AST-ACNs-NPs) was obtained with average sizes of 200 nm, uniform spherical shape and high encapsulation rate of 75%. AST was successfully doped into the nanocarriers, according to the findings of the DFT calculation, fluorescence spectrum, Fourier transform spectroscopy, and UV-vis absorption spectroscopy. Compared with free AST, AST-ACNs-NPs showed better stability under the conditions of high temperature, pH and UV light with<20% activity loss rate. The nano-encapsulation system containing AST could significantly reduce the hydrogen peroxide produced by reactive oxygen species, keep the potential of the mitochondrial membrane at a healthy level, and improve the antioxidant ability of H₂O₂-induced RAW 264.7 cells. These results indicated that microfluidics-based astaxanthin delivery system is an effective solution to improve the bioaccessibility of bioactive substances and has potential application value in food industry.

Uncovering the Fate and Risks of Intravenously Injected Prussian Blue Nanoparticles in mice by an Integrated Methodology of Toxicology, Pharmacokinetics, Proteomics, and Metabolomics

BACKGROUND

Prussian blue (PB) nanoparticles (NPs) have been intensively investigated for medical applications, but an in-depth toxicological investigation of PB NPs has not been implemented. In the present study, a comprehensive investigation of the fate and risks of PB NPs after intravenous administration was carried out by using a mouse model and an integrated methodology of pharmacokinetics, toxicology, proteomics, and metabolomics.

RESULTS

General toxicological studies demonstrated that intravenous administration of PB NPs at 5 or 10 mg/kg could not induce obvious toxicity in mice, while mice treated with a relatively high dose of PB NPs at 20 mg/kg exhibited loss of appetite and weight decrease in the first two days postinjection. Pharmacokinetic studies revealed that intravenously administered PB NPs (20 mg/kg) underwent fast clearance from blood, highly accumulated in the liver and lungs of mice, and finally cleared from tissues. By further integrated proteomics and metabolomics analysis, we found that protein expression and metabolite levels changed significantly in the liver and lungs of mice due to the high accumulation of PB NPs, leading to slight inflammatory responses and intracellular oxidative stress.

CONCLUSIONS

Collectively, our integrated experimental data imply that the high accumulation of PB NPs may cause potential risks to the liver and lungs of mice, which will provide detailed references and guidance for further clinical application of PB NPs in the future.

Intracellular Delivery of Micron-Sized Magnetic Particles through a Virus Infection Pathway

Micron-sized magnetic particles (M-MPs) have low toxicity, strong magnetic signals, and long-term retention capability, which are significant advantages for their application in biomedical imaging. Unfortunately, M-MPs are only internalized by few cell types, such as macrophages and phagocytes, and because of this lack of active intracellular delivery, their applications are restricted. The emergence of self-assembled virus-like particles (VLPs) offers a viable approach to drive M-MPs into cells, although the specific mechanism has not been revealed. In this study, we investigated in detail the intracellular pathway of M-MPs mediated by VLPs using a fluorescence co-localization method. The results indicated that the intracellular movement of M-MPs was consistent with the virus infection pathway, specifically caveolae-dependent endocytosis, transportation through microtubules, and accumulation in the endoplasmic reticulum. This study provides experimental support for the active transport of M-MPs into other cell types, thereby further extending their applications.

Engineering Milk-Derived Exosome for Enhancing Cellular Astaxanthin Delivery

Astaxanthin (AST), a fat-soluble carotenoid, shows excellent antioxidant and anti-inflammatory activities, but its low biocompatibility and stability limit its application in the food industry. In this work, we constructed the targeted hyaluronic acid (HA)-modified milk exosome-based astaxanthin delivery system to improve the biocompatibility stability and targeted transport properties of astaxanthin. Nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) showed that HA was efficiently modified onto the surface of the milk exosome by an amide condensation reaction. The fluorescence images showed that the targeted delivery system accumulated in RAW264.7 macrophages, and the targeting effect on inflammatory cells was significantly enhanced. Compared with free astaxanthin, the delivery system could enhance the cellular uptake of astaxanthin and alleviate the overproduction of reactive oxygen species significantly and the depolarization of mitochondrial membrane potential in a lipopolysaccharide-induced cellular model. The delivery system also notably inhibited the expression of IL-1β, IL-6, and other inflammatory factors. Therefore, the targeted hyaluronic acid-modified milk exosome-based astaxanthin delivery system prevents the activation of macrophages and the production of inflammatory mediators and has the potential to apply to the prevention of chronic inflammatory diseases.

Image-guided/improved diseases management: From immune-strategies and beyond

Timely and accurate assessment and diagnosis are extremely important and beneficial for all diseases, especially for some of the major human disease, such as cancers, cardiovascular diseases, infectious diseases, and neurodegenerative diseases. Limited by the variable disease microenvironment, early imperceptible symptoms, complex immune system interactions, and delayed clinical phenotypes, disease diagnosis and treatment are difficult in most cases. Molecular imaging (MI) techniques can track therapeutic drugs and disease sites in vivo and in vitro in a non-invasive, real-time and visible strategies. Comprehensive visual imaging and quantitative analysis based on different levels can help to clarify the disease process, pathogenesis, drug pharmacokinetics, and further evaluate the therapeutic effects. This review summarizes the application of different MI techniques in the diagnosis and treatment of these major human diseases. It is hoped to shed a light on the development of related technologies and fields.

Perioperative platelet count in peripheral blood is associated with the early stage of PND after major orthopedic surgery: a prospective observational study

Background

Perioperative neurocognitive disorders (PND) are common complications of major surgery among elderly patients, remarkably decreasing patients’ life quality. Platelet count has been proved to be an essential factor in inflammation. However, as far as we know, the relationship between platelet count and PND is not clear yet in the orthopedic area. PND could be a long-term disease, which sometimes lasts for several years, and it is meaningful to find a biomarker of PND at the early stage. Thus, we designed this study to find out the association between perioperative platelet count and occurrence of PND, and determine whether preoperative platelet count could be a biomarker of the early stage of PND.

Methods

A prospective observational study was performed on the patients who would take total knee arthroplasty or total hip arthroplasty. Their peripheral platelets were counted by blood routine examination 1 day before and 3 days after the surgery. And we assessed their neurocognitive functions 1 day before and 3 days after the surgery. These data were recorded and analyzed to find out the relationship between platelet count and the occurrence of PND.

Results

Eventually, 70 patients finished the whole process, and 14 of them developed PND. The median preoperative platelet count in the PND group was significantly higher than that in the non-PND group (239 vs 168 × 10^9/L, p = 0.009). Preoperative platelet count was an independent risk factor for PND (odds ratio = 1.014, 95% confidence interval [CI] 1.000–1.027, P = 0.043) in the logistic multivariable regression, while the area under the curve of the receiver operating characteristic curve of the prediction model was 0.796 (95% CI 0.676–0.916).

Conclusions

The higher preoperative and postoperative level of platelet count in the peripheral blood were associated with the early stage of PND, and preoperative platelet count could be a potential predictor of the early stage of PND in patients undergoing major orthopedic surgeries.

Trial registration

Chinese Clinical Trial Registry: ChiCTR2000033001, registration date: 17 May 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-02899-7.

Impact of Albumin Pre-Coating on Gold Nanoparticles Uptake at Single-Cell Level

Nanoparticles (NPs) suspension is thermodynamically unstable, agglomeration and sedimentation may occur after introducing NPs into a physiological solution, which in turn affects their recognition and uptake by cells. In this work, rod-like gold NPs (AuNRs) with uniform morphology and size were synthesized to study the impact of bovine serum albumin (BSA) pre-coating on the cellular uptake of AuNRs. A comparison study using horizontal and vertical cell culture configurations was performed to reveal the effect of NPs sedimentation on AuNRs uptake at the single-cell level. Our results demonstrate that the well-dispersed AuNRs-BSA complexes were more stable in culture medium than the pristine AuNRs, and therefore were less taken up by cells. The settled AuNRs agglomerates, although only a small fraction of the total AuNRs, weighed heavily in determining the average AuNRs uptake at the population level. These findings highlight the necessity of applying single-cell quantification analysis in the study of the mechanisms underlying the cellular uptake of NPs.