The viral protein corona directs viral pathogenesis and amyloid aggregation

COVID-19 and Neurodegenerative Diseases: Prion-Like Spread and Long-Term Consequences

COVID-19 emerged as a global pandemic starting from Wuhan in China and spread at a lightning speed to the rest of the world. One of the potential long-term outcomes that we speculate is the development of neurodegenerative diseases as a long-term consequence of SARS-CoV-2 especially in people that have developed severe neurological symptoms. Severe inflammatory reactions and aging are two very strong common links between neurodegenerative diseases and COVID-19. Thus, patients that have very high viral load may be at high risk of developing long-term adverse neurological consequences such as dementia. We hypothesize that people with neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and aged people are at higher risk of getting the COVID-19 than normal adults. The basis of this hypothesis is the fact that SARS-CoV-2 uses as a receptor angiotensin-converting enzyme 2 to enter the host cell and that this interaction is calcium-dependent. This could then suggest a direct relationship between neurodegenerative diseases, ACE-2 expression, and the susceptibility to COVID-19. The analysis of the available literature showed that COVID-19 virus is neurotropic and was found in the brains of patients infected with this virus. Furthermore, that the risk of having the infection increases with dementia and that infected people with severe symptoms could develop dementia as a long-term consequence. Dementia could be developed following the acceleration of the spread of prion-like proteins. In the present review we discuss current reports concerning the prevalence of COVID-19 in dementia patients, the individuals that are at high risk of suffering from dementia and the potential acceleration of prion-like proteins spread following SARS-CoV-2 infection.

Modulation of beta-amyloid aggregation using ascorbic acid

Studies have shown that the level of ascorbic acid (AA) is reduced in the brain of Alzheimer's disease (AD) patients. However, its effect on amyloid-β 1-42 (Aβ₄₂) aggregation has not yet been elucidated. Here we investigated for the first time the effect of AA on Aβ₄₂ aggregation using fluorescence assay, circular dichroism, atomic force microscopy, isothermal titration calorimetry, ligand docking, and molecular dynamics. Our results showed that the fibril content decreases in the growth phase when the peptides are co-incubated with AA. AA molecules bind to Aβ₄₂ peptides with high binding affinity and a binding site for AA between the β-strands of Aβ₄₂ oligomers prevents the stack of adjacent strands. We demonstrate the inhibitory effect of AA on the aggregation of Aβ₄₂ and its molecular interactions, which can contribute to the development of an accessible therapy for AD and also to the design of novel drugs for other amyloidogenic diseases.

Antibody-Dependent Complement Responses toward SARS-CoV-2 Receptor-Binding Domain Immobilized on "Pseudovirus-like" Nanoparticles

Many aspects of innate immune responses to SARS viruses remain unclear. Of particular interest is the role of emerging neutralizing antibodies against the receptor-binding domain (RBD) of SARS-CoV-2 in complement activation and opsonization. To overcome challenges with purified virions, here we introduce "pseudovirus-like" nanoparticles with ∼70 copies of functional recombinant RBD to map complement responses. Nanoparticles fix complement in an RBD-dependent manner in sera of all vaccinated, convalescent, and naı̈ve donors, but vaccinated and convalescent donors with the highest levels of anti-RBD antibodies show significantly higher IgG binding and higher deposition of the third complement protein (C3). The opsonization via anti-RBD antibodies is not an efficient process: on average, each bound antibody promotes binding of less than one C3 molecule. C3 deposition is exclusively through the alternative pathway. C3 molecules bind to protein deposits, but not IgG, on the nanoparticle surface. Lastly, "pseudovirus-like" nanoparticles promote complement-dependent uptake by granulocytes and monocytes in the blood of vaccinated donors with high anti-RBD titers. Using nanoparticles displaying SARS-CoV-2 proteins, we demonstrate subject-dependent differences in complement opsonization and immune recognition.

Neuropathological Aspects of SARS-CoV-2 Infection: Significance for Both Alzheimer's and Parkinson's Disease

Evidence suggests that SARS-CoV-2 entry into the central nervous system can result in neurological and/or neurodegenerative diseases. In this review, routes of SARS-Cov-2 entry into the brain via neuroinvasive pathways such as transcribrial, ocular surface or hematogenous system are discussed. It is argued that SARS-Cov-2-induced cytokine storm, neuroinflammation and oxidative stress increase the risk of developing neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Further studies on the effects of SARS-CoV-2 and its variants on protein aggregation, glia or microglia activation, and blood-brain barrier are warranted.

Extracellular vesicles from hair follicle-derived mesenchymal stromal cells: isolation, characterization and therapeutic potential for chronic wound healing

BACKGROUND

Mesenchymal stromal cells (MSCs) and their extracellular vesicles (MSC-EVs) have demonstrated to elicit immunomodulatory and pro-regenerative properties that are beneficial for the treatment of chronic wounds. Thanks to different mediators, MSC-EVs have shown to play an important role in the proliferation, migration and cell survival of different skin cell populations. However, there is still a big bid to achieve the most effective, suitable and available source of MSC-EVs.

METHODS

We isolated, characterized and compared medium-large EVs (m-lEVs) and small EVs (sEVs) obtained from hair follicle-derived MSCs (HF-MSCs) against the gold standard in regenerative medicine, EVs isolated from adipose tissue-derived MSCs (AT-MSCs).

RESULTS

We demonstrated that HF-EVs, as well as AT-EVs, expressed typical MSC-EVs markers (CD9, CD44, CD63, CD81 and CD105) among other different functional markers. We showed that both cell types were able to increase human dermal fibroblasts (HDFs) proliferation and migration. Moreover, both MSC-EVs were able to increase angiogenesis in human umbilical vein endothelial cells (HUVECs) and protect HDFs exposed to a hyperglycemic environment from oxidative stress and cytotoxicity.

CONCLUSIONS

Taken together, HF-EVs demonstrated to exhibit comparable potential to that of AT-EVs as promising candidates in the treatment of chronic wounds.

SARS-CoV-2 Spike Protein Binding of Glycated Serum Albumin-Its Potential Role in the Pathogenesis of the COVID-19 Clinical Syndromes and Bias towards Individuals with Pre-Diabetes/Type 2 Diabetes and Metabolic Diseases

The immune response to SARS-CoV-2 infection requires antibody recognition of the spike protein. In a study designed to examine the molecular features of anti-spike and anti-nucleocapsid antibodies, patient plasma proteins binding to pre-fusion stabilised complete spike and nucleocapsid proteins were isolated and analysed by matrix-assisted laser desorption ionisation–time of flight (MALDI-ToF) mass spectrometry. Amongst the immunoglobulins, a high affinity for human serum albumin was evident in the anti-spike preparations. Careful mass comparison revealed the preferential capture of advanced glycation end product (AGE) forms of glycated human serum albumin by the pre-fusion spike protein. The ability of bacteria and viruses to surround themselves with serum proteins is a recognised immune evasion and pathogenic process. The preference of SARS-CoV-2 for AGE forms of glycated serum albumin may in part explain the severity and pathology of acute respiratory distress and the bias towards the elderly and those with (pre)diabetic and atherosclerotic/metabolic disease.

Proteins Do Not Replicate, They Precipitate: Phase Transition and Loss of Function Toxicity in Amyloid Pathologies

Protein aggregation into amyloid fibrils affects many proteins in a variety of diseases, including neurodegenerative disorders, diabetes, and cancer. Physicochemically, amyloid formation is a phase transition process, where soluble proteins are transformed into solid fibrils with the characteristic cross-β conformation responsible for their fibrillar morphology. This phase transition proceeds via an initial, rate-limiting nucleation step followed by rapid growth. Several well-defined nucleation pathways exist, including homogenous nucleation (HON), which proceeds spontaneously; heterogeneous nucleation (HEN), which is catalyzed by surfaces; and seeding via preformed nuclei. It has been hypothesized that amyloid aggregation represents a protein-only (nucleic-acid free) replication mechanism that involves transmission of structural information via conformational templating (the prion hypothesis). While the prion hypothesis still lacks mechanistic support, it is also incompatible with the fact that proteins can be induced to form amyloids in the absence of a proteinaceous species acting as a conformational template as in the case of HEN, which can be induced by lipid membranes (including viral envelopes) or polysaccharides. Additionally, while amyloids can be formed from any protein sequence and via different nucleation pathways, they invariably adopt the universal cross-β conformation; suggesting that such conformational change is a spontaneous folding event that is thermodynamically favorable under the conditions of supersaturation and phase transition and not a templated replication process. Finally, as the high stability of amyloids renders them relatively inert, toxicity in some amyloid pathologies might be more dependent on the loss of function from protein sequestration in the amyloid state rather than direct toxicity from the amyloid plaques themselves.

Role of HSV-1 in Alzheimer's disease pathogenesis: A challenge for novel preventive/therapeutic strategies

Herpes simplex virus-1 (HSV-1) is a ubiquitous DNA virus able to establish a life-long latent infection in host sensory ganglia. Following periodic reactivations, the neovirions usually target the site of primary infection causing recurrent diseases in susceptible individuals. However, reactivated HSV-1 may also reach the brain resulting in severe herpetic encephalitis or in asymptomatic infections. These have been reportedly linked to neurodegenerative disorders, such as Alzheimer's disease (AD), suggesting antiviral preventive or/therapeutic treatments as possible strategies to counteract AD onset and progression. Here, we provide an overview of the AD-like mechanisms driven by HSV-1-infection in neurons and discuss the ongoing trials repurposing anti-herpetic drugs to treat AD as well as preventive strategies aimed at blocking virus infection.

Amyloid-β peptide 37, 38 and 40 individually and cooperatively inhibit amyloid-β 42 aggregation

The pathology of Alzheimer's disease is connected to the aggregation of β-amyloid (Aβ) peptide, which in vivo exists as a number of length-variants. Truncations and extensions are found at both the N- and C-termini, relative to the most commonly studied 40- and 42-residue alloforms. Here, we investigate the aggregation of two physiologically abundant alloforms, Aβ37 and Aβ38, as pure peptides and in mixtures with Aβ40 and Aβ42. A variety of molar ratios were applied in quaternary mixtures to investigate whether a certain ratio is maximally inhibiting of the more toxic alloform Aβ42. Through kinetic analysis, we show that both Aβ37 and Aβ38 self-assemble through an autocatalytic secondary nucleation reaction to form fibrillar β-sheet-rich aggregates, albeit on a longer timescale than Aβ40 or Aβ42. Additionally, we show that the shorter alloforms co-aggregate with Aβ40, affecting both the kinetics of aggregation and the resulting fibrillar ultrastructure. In contrast, neither Aβ37 nor Aβ38 forms co-aggregates with Aβ42; however, both short alloforms reduce the rate of Aβ42 aggregation in a concentration-dependent manner. Finally, we show that the aggregation of Aβ42 is more significantly impeded by a combination of Aβ37, Aβ38, and Aβ40 than by any of these alloforms independently. These results demonstrate that the aggregation of any given Aβ alloform is significantly perturbed by the presence of other alloforms, particularly in heterogeneous mixtures, such as is found in the extracellular fluid of the brain.

Scratching the Surface of the Protein Corona: Challenging Measurements and Controversies

This Review aims to provide a systematic analysis of the literature regarding ongoing debates in protein corona research. Our goal is to portray the current understanding of two fundamental and debated characteristics of the protein corona, namely, the formation of mono- or multilayers of proteins and their binding (ir)reversibility. The statistical analysis we perform reveals that these characterisitics are strongly correlated to some physicochemical factors of the NP-protein system (particle size, bulk material, protein type), whereas the technique of investigation or the type of measurement (in situ or ex situ) do not impact the results, unlike commonly assumed. Regarding the binding reversibility, the experimental design (either dilution or competition experiments) is also shown to be a key factor, probably due to nontrivial protein binding mechanisms, which could explain the paradoxical phenomena reported in the literature. Overall, we suggest that to truly predict and control the protein corona, future efforts should be directed toward the mechanistic aspects of protein adsorption.

Virus-like particles against infectious disease and cancer: guidance for the nano-architect

Virus-like particles (VLPs) can play important roles in prevention and therapy for infectious diseases and cancer. Here we describe recent advances in rational construction of VLP assemblies, as well as new approaches to enhance long-lasting antibody and CD8⁺ T cell responses. DNA origami and computational protein design identified optimal spacing of antigens. Chemical biology advances enabled simple and irreversible VLP decoration with protein or polysaccharide antigens. Mosaic VLPs co-displayed antigens to generate cross-reactive antibodies against different influenza strains and coronaviruses. The mode of action of adjuvants inside VLPs was established through knock-outs and repackaging of innate immune stimuli. VLPs themselves showed their power as adjuvants in cancer models. Finally, landmark clinical results were obtained against malaria and the SARS-CoV-2 pandemic.

The impact of protein corona on the biological behavior of targeting nanomedicines

For successful translation of targeting nanomedicines from bench to bedside, it is vital to address their most common drawbacks namely rapid clearance and off-target accumulation. These complications evidently originate from a phenomenon called "protein corona (PC) formation" around the surface of targeting nanoparticles (NPs) which happens once they encounter the bloodstream and interact with plasma proteins with high collision frequency. This phenomenon endows the targeting nanomedicines with a different biological behavior followed by an unexpected fate, which is usually very different from what we commonly observe in vitro. In addition to the inherent physiochemical properties of NPs, the targeting ligands could also remarkably dictate the amount and type of adsorbed PC. As very limited studies have focused their attention on this particular factor, the present review is tasked to discuss the best simulated environment and latest characterization techniques applied to PC analysis. The effect of PC on the biological behavior of targeting NPs engineered with different targeting moieties is further discussed. Ultimately, the recent progresses in manipulation of nano-bio interfaces to achieve the most favorite therapeutic outcome are highlighted.

Interactions between SARS-CoV-2 N-Protein and α-Synuclein Accelerate Amyloid Formation

First cases that point at a correlation between SARS-CoV-2 infections and the development of Parkinson’s disease (PD) have been reported. Currently, it is unclear if there is also a direct causal link between these diseases. To obtain first insights into a possible molecular relation between viral infections and the aggregation of α-synuclein protein into amyloid fibrils characteristic for PD, we investigated the effect of the presence of SARS-CoV-2 proteins on α-synuclein aggregation. We show, in test tube experiments, that SARS-CoV-2 spike protein (S-protein) has no effect on α-synuclein aggregation, while SARS-CoV-2 nucleocapsid protein (N-protein) considerably speeds up the aggregation process. We observe the formation of multiprotein complexes and eventually amyloid fibrils. Microinjection of N-protein in SH-SY5Y cells disturbed the α-synuclein proteostasis and increased cell death. Our results point toward direct interactions between the N-protein of SARS-CoV-2 and α-synuclein as molecular basis for the observed correlation between SARS-CoV-2 infections and Parkinsonism.

Simultaneous Detection of Herpes Simplex Virus Type 1 Latent and Lytic Transcripts in Brain Tissue

Neurotrophic herpes simplex virus type 1 (HSV-1) establishes lifelong latent infection in humans. Accumulating studies indicate that HSV-1, a risk factor of neurodegenerative diseases, exacerbates the sporadic Alzheimer's disease (AD). The analysis of viral genetic materials via genomic sequencing and quantitative PCR (qPCR) is the current approach used for the detection of HSV-1; however, this approach is limited because of its difficulty in detecting both latent and lytic phases of the HSV-1 life cycle in infected hosts. RNAscope, a novel in situ RNA hybridization assay, enables visualized detection of multiple RNA targets on tissue sections. Here, we developed a fluorescent multiplex RNAscope assay in combination with immunofluorescence to detect neuronal HSV-1 transcripts in various types of mouse brain samples and human brain tissues. Specifically, the RNA probes were designed to separately recognize two transcripts in the same brain section: (1) the HSV-1 latency-associated transcript (LAT) and (2) the lytic-associated transcript, the tegument protein gene of the unique long region 37 (UL37). As a result, both LAT and UL37 signals were detectable in neurons in the hippocampus and trigeminal ganglia (TG). The quantifications of HSV-1 transcripts in the TG and CNS neurons are correlated with the viral loads during lytic and latent infection. Collectively, the development of combinational detection of neuronal HSV-1 transcripts in mouse brains can serve as a valuable tool to visualize HSV-1 infection phases in various types of samples from AD patients and facilitate our understanding of the infectious origin of neurodegeneration and dementia.

Disrupting Neurons and Glial Cells Oneness in the Brain-The Possible Causal Role of Herpes Simplex Virus Type 1 (HSV-1) in Alzheimer's Disease

Current data strongly suggest herpes simplex virus type 1 (HSV-1) infection in the brain as a contributing factor to Alzheimer's disease (AD). The consequences of HSV-1 brain infection are multilateral, not only are neurons and glial cells damaged, but modifications also occur in their environment, preventing the transmission of signals and fulfillment of homeostatic and immune functions, which can greatly contribute to the development of disease. In this review, we discuss the pathological alterations in the central nervous system (CNS) cells that occur, following HSV-1 infection. We describe the changes in neurons, astrocytes, microglia, and oligodendrocytes related to the production of inflammatory factors, transition of glial cells into a reactive state, oxidative damage, Aβ secretion, tau hyperphosphorylation, apoptosis, and autophagy. Further, HSV-1 infection can affect processes observed during brain aging, and advanced age favors HSV-1 reactivation as well as the entry of the virus into the brain. The host activates pattern recognition receptors (PRRs) for an effective antiviral response during HSV-1 brain infection, which primarily engages type I interferons (IFNs). Future studies regarding the influence of innate immune deficits on AD development, as well as supporting the neuroprotective properties of glial cells, would reveal valuable information on how to harness cytotoxic inflammatory milieu to counter AD initiation and progression.

Can SARS-CoV-2 Infection Lead to Neurodegeneration and Parkinson's Disease?

The SARS-CoV-2 pandemic has affected the daily life of the worldwide population since 2020. Links between the newly discovered viral infection and the pathogenesis of neurodegenerative diseases have been investigated in different studies. This review aims to summarize the literature concerning COVID-19 and Parkinson's disease (PD) to give an overview on the interface between viral infection and neurodegeneration with regard to this current topic. We will highlight SARS-CoV-2 neurotropism, neuropathology and the suspected pathophysiological links between the infection and neurodegeneration as well as the psychosocial impact of the pandemic on patients with PD. Some evidence discussed in this review suggests that the SARS-CoV-2 pandemic might be followed by a higher incidence of neurodegenerative diseases in the future. However, the data generated so far are not sufficient to confirm that COVID-19 can trigger or accelerate neurodegenerative diseases.

No evidence of aberrant amyloid β and phosphorylated tau expression in herpes simplex virus-infected neurons of the trigeminal ganglia and brain

Increasing evidence supports the role of neurotropic herpes simplex virus 1 (HSV‐1) in the pathogenesis of Alzheimer's disease (AD). However, it is unclear whether previously reported findings in HSV‐1 cell culture and animal models can be translated to humans. Here, we analyzed clinical specimens from latently HSV‐1 infected individuals and individuals with lytic HSV infection of the brain (herpes simplex encephalitis; HSE). Latent HSV‐1 DNA load and latency‐associated transcript (LAT) expression were identical between trigeminal ganglia (TG) of AD patients and controls. Amyloid β (Aβ) and hyperphosphorylated tau (pTau) were not detected in latently HSV‐infected TG neurons. Aging‐related intraneuronal Aβ accumulations, neurofibrillary tangles (NFT), and/or extracellular Aβ plaques were observed in the brain of some HSE patients, but these were neither restricted to HSV‐infected neurons nor brain regions containing virus‐infected cells. Analysis of unique brain material from an AD patient with concurrent HSE showed that HSV‐infected cells frequently localized close to Aβ plaques and NFT, but were not associated with exacerbated AD‐related pathology. HSE‐associated neuroinflammation was not associated with specific Aβ or pTau phenotypes. Collectively, we observed that neither latent nor lytic HSV infection of human neurons is directly associated with aberrant Aβ or pTau protein expression in ganglia and brain.

Modulation of the Conformational Space of SARS-CoV-2 RNA Quadruplex RG-1 by Cellular Components and the Amyloidogenic Peptides α-Synuclein and hIAPP

Given the emergence of the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), which particularly threatens older people with comorbidities such as diabetes mellitus and dementia, understanding the relationship between Covid-19 and other diseases is an important factor for treatment. Possible targets for medical intervention include G-quadruplexes (G4Qs) and their protein interaction partners. We investigated the stability and conformational space of the RG-1 RNA-G-quadruplex of the SARS-CoV-2 N-gene in the presence of salts, cosolutes, crowders and intrinsically disordered peptides, focusing on α-Synuclein and the human islet amyloid polypeptide, which are involved in Parkinson's disease (PD) and type-II diabetes mellitus (T2DM), respectively. We found that the conformational dynamics of the RG-1 G4Q is strongly affected by the various solution conditions. Further, the amyloidogenic peptides were found to strongly modulate the conformational equilibrium of the RG-1. Considerable changes are observed with respect to their interaction with human telomeric G4Qs, which adopt different topologies. These results may therefore shed more light on the relationship between PD as well as T2DM and the SARS-CoV-2 disease and their molecular underpinnings. Since dysregulation of G4Q formation by rationally designed targeting compounds affects the control of cellular processes, this study should contribute to the development of specific ligands for intervention.

Blood Nanoparticles - Influence on Extracellular Vesicle Isolation and Characterization

Blood is a rich source of disease biomarkers, which include extracellular vesicles (EVs). EVs are nanometer-to micrometer-sized spherical particles that are enclosed by a phospholipid bilayer and are secreted by most cell types. EVs reflect the physiological cell of origin in terms of their molecular composition and biophysical characteristics, and they accumulate in blood even when released from remote organs or tissues, while protecting their cargo from degradation. The molecular components (e.g., proteins, miRNAs) and biophysical characteristics (e.g., size, concentration) of blood EVs have been studied as biomarkers of cancers and neurodegenerative, autoimmune, and cardiovascular diseases. However, most biomarker studies do not address the problem of contaminants in EV isolates from blood plasma, and how these might affect downstream EV analysis. Indeed, nonphysiological EVs, protein aggregates, lipoproteins and viruses share many molecular and/or biophysical characteristics with EVs, and can therefore co-isolate with EVs from blood plasma. Consequently, isolation and downstream analysis of EVs from blood plasma remain a unique challenge, with important impacts on the outcomes of biomarker studies. To help improve rigor, reproducibility, and reliability of EV biomarker studies, we describe here the major contaminants of EV isolates from blood plasma, and we report on how different EV isolation methods affect their levels, and how contaminants that remain can affect the interpretation of downstream EV analysis.

Unraveling the Effect of Breast Cancer Patients' Plasma on the Targeting Ability of Folic Acid-Modified Chitosan Nanoparticles

The formation of protein corona (PC) around nanoparticles (NPs) has been reported inside biological conditions. This effect can alter delivery capacity toward the targeted tissues. Here, we synthesized folic acid-modified chitosan NPs (FA-CS NPs) using different concentrations of folic acid (5, 10, and 20%). FA-CS NPs were exposed to plasmas of breast cancer patients and healthy donors to evaluate the possibility of PC formation. We also monitored uptake efficiency in in vitro conditions after incubation with human breast cancer cell line MDA-MB-231 and monocyte/macrophage-like Raw264.7 cells. Data showed that the formation of PC around FA-CS NPs can change physicochemical properties coincided with the rise in NP size and negative surface charge. SDS-PAGE electrophoresis revealed differences in the type and content rate of plasma proteins attached to NP surface in a personalized manner. Based on MTT data, the formation of PC around NPs did not exert cytotoxic effects on MDA-MB-231 cells while this phenomenon reduced uptake rate. Fluorescence imaging and flow cytometry analyses revealed reduced cellular internalization rate in NPs exposed to patients' plasma compared to the control group. In contrast to breast MDA-MB-231 cells, Raw264.7 cells efficiently adsorbed the bare and PC-coated NPs from both sources, indicating the involvement of ligand-receptor-dependent and independent cellular engulfment. These data showed that the PC formed on the FA-CS NPs is entirely different in breast cancer patients and healthy counterparts. PC derived from patients' plasma almost abolishes the targeting efficiency of FA-CS NPs even in different mechanisms, while this behavior was not shown in the control group. Surprisingly, Raw264.7 cells strongly adsorbed the PC-coated NPs, especially when these particles were in the presence of patients' sera. It is strongly suggested that the formation of PC around can affect delivering capacity of FA-CS NPs to cancer cells. It seems that the PC-coated FA-CS NPs can be used as an efficient delivery strategy for the transfer of specific biomolecules in immune system disorders.

Virus-inspired nanosystems for drug delivery

With over millions of years of evolution, viruses can infect cells efficiently by utilizing their unique structures. Similarly, the drug delivery process is designed to imitate the viral infection stages for maximizing the therapeutic effect. From drug administration to therapeutic effect, nanocarriers must evade the host's immune system, break through multiple barriers, enter the cell, and release their payload by endosomal escape or nuclear targeting. Inspired by the virus infection process, a number of virus-like nanosystems have been designed and constructed for drug delivery. This review aims to present a comprehensive summary of the current understanding of the drug delivery process inspired by the viral infection stages. The most recent construction of virus-inspired nanosystems (VINs) for drug delivery is sorted, emphasizing their novelty and design principles, as well as highlighting the mechanism of these nanosystems for overcoming each biological barrier during drug delivery. A perspective on the VINs for therapeutic applications is provided in the end.

Interfacial Interactions within Amyloid Protein Corona Based on 2D MoS2 Nanosheets

The interfacial interaction within the amyloid protein corona based on MoS₂ nanomaterial is crucial, both for understanding the biological effects of MoS₂ nanomaterial and the evolution of amyloid diseases. The specific nano-bio interface phenomenon of human islet amyloid peptide (hIAPP) and MoS₂ nanosheet was investigated by using theoretical and experimental methods. The MoS₂ nanosheet enables the attraction of hIAPP monomer, dimer, and oligomer on its surface through van der Waals forces. Especially, the means of interaction between two hIAPP peptides might be changed by MoS₂ nanosheet. In addition, it is interesting to find that the hIAPP oligomer can stably interact with the MoS₂ nanosheet in one unique "standing" binding mode with an entire exposed β-sheet surface. All the interaction modes on the surface of MoS₂ nanosheet can be the essence of amyloid protein corona that may provide the venue to facilitate the fibrillation of hIAPP proteins. Further, it was verified experimentally that MoS₂ nanosheets could accelerate the fibrillation of hIAPP at a certain concentration mainly based on the newly formed nano-bio interface. In general, our results provide insight into the molecular interaction mechanism of the nano-bio interface within the amyloid protein corona, and shed light on the pathway of amyloid protein aggregation that is related to the evolution of amyloid diseases.

A nano perspective behind the COVID-19 pandemic

The global pandemic scenario has definitely pushed the scientific community to develop COVID-19 vaccines at unprecedented speed. Nevertheless, a worldwide vaccination campaign is still far from being achieved, making the usual precautionary measures as necessary as at the beginning of the outbreak. Many aspects of the SARS-CoV-2 infectious potential and disease severity do not solely rely on interactions at the molecular level but also on physical-chemical parameters that often involve nanoscale effects. Here the SARS-CoV-2 journey to infect a susceptible host is reviewed, focusing on the nanoscale aspects that play a role in the viral infectivity and disease progression. These nanoscale-driven interactions are essential to establish mitigation-related strategies.

Indication of Neurodegenerative Cascade Initiation by Amyloid-like Aggregate-Forming EBV Proteins and Peptide in Alzheimer's Disease

The neurotropic potential of the Epstein-Barr virus (EBV) was demonstrated quite recently; however, the mechanistic details are yet to be explored. Therefore, the effects of EBV infection in the neural milieu remain underexplored. Previous reports have suggested the potential role of virus-derived peptides in seeding the amyloid-β aggregation cascade, which lies at the center of Alzheimer's disease (AD) pathophysiology. However, no such study has been undertaken to explore the role of EBV peptides in AD. In our research, ∼100 EBV proteins were analyzed for their aggregation proclivity in silico using bioinformatic tools, followed by the prediction of 20S proteasomal cleavage sites using online algorithms NetChop ver. 3.1 and Pcleavage, thereby mimicking the cellular proteasomal cleavage activity generating short antigenic peptides of viral origin. Our study reports a high aggregate-forming tendency of a 12-amino-acid-long (₁₄₆SYKHVFLSAFVY₁₅₇) peptide derived from EBV glycoprotein M (EBV-gM). The in vitro analysis of aggregate formation done using Congo red and Thioflavin-S assays demonstrated dose- and time-dependent kinetics. Thereafter, Raman spectroscopy was used to validate the formation of secondary structures (α helix, β sheets) in the aggregates. Additionally, cytotoxicity assay revealed that even a low concentration of these aggregates has a lethal effect on neuroblastoma cells. The findings of this study provide insights into the mechanistic role of EBV in AD and open up new avenues to explore in the future.

Low soluble amyloid-β 42 is associated with smaller brain volume in Parkinson's disease

INTRODUCTION

We sought to examine whether levels of soluble alpha-synuclein (α-syn), amyloid-beta (Aβ42), phosphorylated tau (p-tau), and total tau (t-tau), as measured in cerebrospinal fluid (CSF), are associated with changes in brain volume in Parkinson's disease.

METHODS

We assessed the 4-year change in total brain volume (n = 99) and baseline CSF α-syn, Aβ42, p-tau, and t-tau of Parkinson Progression Markers Initiative participants. We used linear mixed models to assess the longitudinal effect of baseline CSF biomarkers on total and regional brain volume and thickness as well as linear regression for cross-sectional analyses at baseline and year 2. All models were adjusted for age and gender; brain volume models also adjusted for baseline intracranial volume. Bonferroni correction was applied.

RESULTS

The 4-year change in total brain volume was -21.2 mm³ (95% confidence interval, -26.1, -16.3). There were no significant associations between the 4-year change in total brain volume and baseline levels of any CSF biomarker (all p-values > 0.05). On cross-sectional analyses, CSF Aβ42 was linearly associated with total brain volume at baseline (R² = 0.60, p = 0.0004) and at year 2 (R² = 0.66, p < 0.0001), with CSF Aβ42 < 1100 pg/ml, the threshold for brain amyloid pathology, associated with smaller total brain volume at baseline (p = 0.0010) and at year 2 (p = 0.0002). CSF α-syn was linearly associated with total brain volume at baseline (R² = 0.58, p = 0.0044) but not at year 2 (R² = 0.58, p = 0.1342).

CONCLUSION

Reduction in soluble Aβ42 is associated with lower total brain volume in Parkinson's disease.

Rift Valley fever virus: a new avenue of research on the biological functions of amyloids?

Rift Valley fever is a mosquito-borne viral zoonosis that was first discovered in the Great Rift Valley, Kenya, in 1930. Rift Valley fever virus (RVFV) primarily infects domestic animals and humans, with clinical outcomes ranging from self-limiting febrile illness to acute hepatitis and encephalitis. The virus left Africa a few decades ago, and there is a risk of introduction into southern Europe and Asia. From this perspective, we introduce RVFV and focus on the capacity of its virulence factor, the nonstructural protein NSs, to form amyloid-like fibrils. Here, we discuss the implications for the NSs biological function, the ability of RVFV to evade innate immunity, and RVFV virulence and neurotoxicity.

The Hippocampal Vulnerability to Herpes Simplex Virus Type I Infection: Relevance to Alzheimer's Disease and Memory Impairment

Herpes simplex virus type 1 (HSV-1) as a possible infectious etiology in Alzheimer’s disease (AD) has been proposed since the 1980s. The accumulating research thus far continues to support the association and a possible causal role of HSV-1 in the development of AD. HSV-1 has been shown to induce neuropathological and behavioral changes of AD, such as amyloid-beta accumulation, tau hyperphosphorylation, as well as memory and learning impairments in experimental settings. However, a neuroanatomical standpoint of HSV-1 tropism in the brain has not been emphasized in detail. In this review, we propose that the hippocampal vulnerability to HSV-1 infection plays a part in the development of AD and amnestic mild cognitive impairment (aMCI). Henceforth, this review draws on human studies to bridge HSV-1 to hippocampal-related brain disorders, namely AD and aMCI/MCI. Next, experimental models and clinical observations supporting the neurotropism or predilection of HSV-1 to infect the hippocampus are examined. Following this, factors and mechanisms predisposing the hippocampus to HSV-1 infection are discussed. In brief, the hippocampus has high levels of viral cellular receptors, neural stem or progenitor cells (NSCs/NPCs), glucocorticoid receptors (GRs) and amyloid precursor protein (APP) that support HSV-1 infectivity, as well as inadequate antiviral immunity against HSV-1. Currently, the established diseases HSV-1 causes are mucocutaneous lesions and encephalitis; however, this review revises that HSV-1 may also induce and/or contribute to hippocampal-related brain disorders, especially AD and aMCI/MCI.

Management of Parkinson's Disease in the COVID-19 Pandemic and Future Perspectives in the Era of Vaccination

The current coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to a serious global health crisis. Increasing evidence suggests that elderly individuals with underlying chronic diseases, including Parkinson's disease (PD), are particularly vulnerable to this infection. Changes in the routine care of PD patients should be implemented carefully without affecting the quality provided. The utilization of telemedicine for clinical consultation, assessment and rehabilitation has also been widely recommended. Therefore, the aim of this review is to provide recommendations in the management of PD during the pandemic as well as in the early phase of vaccination programs to highlight the potential sequelae and future perspectives of vaccination and further research in PD. Even though a year has passed since COVID- 19 emerged, most of us are still facing great challenges in providing a continuum of care to patients with chronic neurological disorders. However, we should regard this health crisis as an opportunity to change our routine approach in managing PD patients and learn more about the impact of SARS-CoV-2. Hopefully, PD patients can be vaccinated promptly, and more detailed research related to PD in COVID-19 can still be carried out.

Formation of a protein corona on the surface of extracellular vesicles in blood plasma

In this study we tested whether a protein corona is formed around extracellular vesicles (EVs) in blood plasma. We isolated medium-sized nascent EVs of THP1 cells as well as of Optiprep-purified platelets, and incubated them in EV-depleted blood plasma from healthy subjects and from patients with rheumatoid arthritis. EVs were subjected to differential centrifugation, size exclusion chromatography, or density gradient ultracentrifugation followed by mass spectrometry. Plasma protein-coated EVs had a higher density compared to the nascent ones and carried numerous newly associated proteins. Interactions between plasma proteins and EVs were confirmed by confocal microscopy, capillary Western immunoassay, immune electron microscopy and flow cytometry. We identified nine shared EV corona proteins (ApoA1, ApoB, ApoC3, ApoE, complement factors 3 and 4B, fibrinogen α-chain, immunoglobulin heavy constant γ2 and γ4 chains), which appear to be common corona proteins among EVs, viruses and artificial nanoparticles in blood plasma. An unexpected finding of this study was the high overlap of the composition of the protein corona with blood plasma protein aggregates. This is explained by our finding that besides a diffuse, patchy protein corona, large protein aggregates also associate with the surface of EVs. However, while EVs with an external plasma protein cargo induced an increased expression of TNF-α, IL-6, CD83, CD86 and HLA-DR of human monocyte-derived dendritic cells, EV-free protein aggregates had no effect. In conclusion, our data may shed new light on the origin of the commonly reported plasma protein 'contamination' of EV preparations and may add a new perspective to EV research.

Extracellular protein components of amyloid plaques and their roles in Alzheimer's disease pathology

Alzheimer's disease (AD) is pathologically defined by the presence of fibrillar amyloid β (Aβ) peptide in extracellular senile plaques and tau filaments in intracellular neurofibrillary tangles. Extensive research has focused on understanding the assembly mechanisms and neurotoxic effects of Aβ during the last decades but still we only have a brief understanding of the disease associated biological processes. This review highlights the many other constituents that, beside Aβ, are accumulated in the plaques, with the focus on extracellular proteins. All living organisms rely on a delicate network of protein functionality. Deposition of significant amounts of certain proteins in insoluble inclusions will unquestionably lead to disturbances in the network, which may contribute to AD and copathology. This paper provide a comprehensive overview of extracellular proteins that have been shown to interact with Aβ and a discussion of their potential roles in AD pathology. Methods that can expand the knowledge about how the proteins are incorporated in plaques are described. Top-down methods to analyze post-mortem tissue and bottom-up approaches with the potential to provide molecular insights on the organization of plaque-like particles are compared. Finally, a network analysis of Aβ-interacting partners with enriched functional and structural key words is presented.

Single-Cell RNA Sequencing of Peripheral Blood Reveals Immune Cell Signatures in Alzheimer's Disease

The peripheral immune system is thought to affect the pathology of the central nervous system in Alzheimer’s disease (AD). However, current knowledge is inadequate for understanding the characteristics of peripheral immune cells in AD. This study aimed to explore the molecular basis of peripheral immune cells and the features of adaptive immune repertoire at a single cell level. We profiled 36,849 peripheral blood mononuclear cells from AD patients with amyloid-positive status and normal controls with amyloid-negative status by 5’ single-cell transcriptome and immune repertoire sequencing using the cell ranger standard analysis procedure. We revealed five immune cell subsets: CD4+ T cells, CD8+ T cells, B cells, natural killer cells, and monocytes–macrophages cells, and disentangled the characteristic alterations of cell subset proportion and gene expression patterns in AD. Thirty-one cell type-specific key genes, comprising abundant human leukocyte antigen genes, and multiple immune-related pathways were identified by protein–protein interaction network and pathway enrichment analysis. We also found high-frequency amplification clonotypes in T and B cells and decreased diversity in T cells in AD. As clone amplification suggested the activation of an adaptive immune response against specific antigens, we speculated that the peripheral adaptive immune response, especially mediated by T cells, may have a role in the pathogenesis of AD. This finding may also contribute to further research regarding disease mechanism and the development of immune-related biomarkers or therapy.

Soluble Amyloid-β Consumption in Alzheimer's Disease

Brain proteins function in their soluble, native conformation and cease to function when transformed into insoluble aggregates, also known as amyloids. Biophysically, the soluble-to-insoluble phase transformation represents a process of polymerization, similar to crystallization, dependent on such extrinsic factors as concentration, pH, and a nucleation surface. The resulting cross-β conformation of the insoluble amyloid is markedly stable, making it an unlikely source of toxicity. The spread of brain amyloidosis can be fully explained by mechanisms of spontaneous or catalyzed polymerization and phase transformation instead of active replication, which is an enzyme- and energy-requiring process dependent on a specific nucleic acid code for the transfer of biological information with high fidelity. Early neuronal toxicity in Alzheimer's disease may therefore be mediated to a greater extent by a reduction in the pool of soluble, normal-functioning protein than its accumulation in the polymerized state. This alternative loss-of-function hypothesis of pathogenicity can be examined by assessing the clinical and neuroimaging effects of administering non-aggregating peptide analogs to replace soluble amyloid-β levels above the threshold below which neuronal toxicity may occur. Correcting the depletion of soluble amyloid-β, however, would only exemplify 'rescue medicine.' Precision medicine will necessitate identifying the pathogenic factors catalyzing the protein aggregation in each affected individual. Only then can we stratify patients for etiology-specific treatments and launch precision medicine for Alzheimer's disease and other neurodegenerative disorders.

Interaction of serum proteins with SARS-CoV-2 RBD

The outbreak of the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has become a worldwide public health crisis. When the SARS-CoV-2 enters the biological fluids in the human body, different types of biomolecules (in particular proteins) may adsorb on its surface and alter its infection ability. Although great efforts have recently been devoted to the interaction of specific antibodies with the SARS-CoV-2, it still remains largely unknown how the other serum proteins affect the infection of the SARS-CoV-2. In this work, we systematically investigate the interaction of serum proteins with the SARS-CoV-2 RBD by molecular docking and all-atom molecular dynamics simulations. It is found that non-specific immunoglobulins (Ig) indeed cannot effectively bind to the SARS-CoV-2 RBD while human serum albumin (HSA) may have some potential in blocking its infection (to ACE2). More importantly, we find that the RBD can cause significant structural changes in Apolipoprotein E (ApoE), by which SARS-CoV-2 may hijack the metabolic pathway of ApoE to facilitate its cell entry. The present study enhances the understanding of the role of protein corona in the bio-behaviors of SARS-CoV-2, which may aid the more precise and personalized treatment for COVID-19 infection in the clinic.

Inherited and acquired corona of coronavirus in the host: Inspiration from the biomolecular corona of nanoparticles

The family of coronavirus are named for their crown shape. Encoded by the genetic material inherited from the coronavirus itself, this intrinsic well-known "viral corona" is considered an "inherited corona". After contact with mucosa or the entrance into the host, bare coronaviruses can become covered by a group of dissolved biomolecules to form one or multiple layers of biomolecules. The layers acquired from the surrounding environment are named the "acquired corona". We highlight here the possible role of the acquired corona in the pathogenesis of coronaviruses, which will generate fresh insight into the nature of various coronavirus-host interactions.

Robust sequential biophysical fractionation of blood plasma to study variations in the biomolecular landscape of systemically circulating extracellular vesicles across clinical conditions

Separating extracellular vesicles (EV) from blood plasma is challenging and complicates their biological understanding and biomarker development. In this study, we fractionate blood plasma by combining size-exclusion chromatography (SEC) and OptiPrep density gradient centrifugation to study clinical context-dependent and time-dependent variations in the biomolecular landscape of systemically circulating EV. Using pooled blood plasma samples from breast cancer patients, we first demonstrate the technical repeatability of blood plasma fractionation. Using serial blood plasma samples from HIV and ovarian cancer patients (n = 10) we next show that EV carry a clinical context-dependent and/or time-dependent protein and small RNA composition, including miRNA and tRNA. In addition, differential analysis of blood plasma fractions provides a catalogue of putative proteins not associated with systemically circulating EV. In conclusion, the implementation of blood plasma fractionation allows to advance the biological understanding and biomarker development of systemically circulating EV.

Old dog, new tricks: Influenza A virus NS1 and in vitro fibrillogenesis

The influenza NS1 protein is involved in suppression of the host immune response. Recently, there is growing evidence that prion-like protein aggregation plays an important role in cellular signaling and immune responses. In this work, we obtained a recombinant, influenza A NS1 protein and showed that it is able to form amyloid-like fibrils in vitro. Using proteolysis and subsequent mass spectrometry, we showed that regions resistant to protease hydrolysis highly differ between the native NS1 form (NS1-N) and fibrillar form (NS1-F); this indicates that significant structural changes occur during fibril formation. We also found a protein fragment that is capable of inducing the process of fibrillogenesis at 37 °C. The discovery of the ability of NS1 to form amyloid-like fibrils may be relevant to uncovering relationships between influenza A infection and modulation of the immune response.

An update on Alzheimer's disease: Immunotherapeutic agents, stem cell therapy and gene editing

Alzheimer's disease is a chronic lifestyle ailment whose occurrence has come to light with the increasing life expectancy due to better healthcare. The patient burden for AD is set to double by the year 2060 and advancement in research is of utmost importance to combat this problem. AD is characterized by the pathological hallmarks of amyloid plaques and neurofibrillary tangles. The disease has been implicated to have a genetic predisposition. The current treatment strategies are at best ameliorative in nature and offer no substantive cure. Immunotherapeutic approaches employed have shown few therapeutic benefits but the accelerated approval of aducanumab by the US-FDA shows clinical benefit merit. In addition, newer therapeutic approaches are the need of the hour. This review aims to highlight the pathology of the disease, followed by an insight into newer approaches like stem cell therapy and gene editing, focusing on possible CRISPR mediated targets.

Protein corona modulates interaction of spiky nanoparticles with lipid bilayers

The impact of protein corona on the interactions of nanoparticles (NPs) with cells remains an open question. This question is particularly relevant to NPs which sizes, ranging from tens to hundreds nanometers, are comparable to the sizes of most abundant proteins in plasma. Protein sizes match with typical thickness of various coatings and ligands layers, usually present at the surfaces of larger NPs. Such size match may affect the properties and the designed function of NPs. We offer a direct demonstration of how protein corona can dramatically change the interaction mode between NPs and lipid bilayers. To this end, we choose the most extreme case of NP surface modification: nanostructures in the form of rigid spikes of 10-20 nm length at the surface of gold nanoparticles. In the absence of proteins we observe the formation of reversible pores when spiky NPs adsorb on lipid bilayers. In contrast, the presence of bovine serum albumin (BSA) proteins adsorbed at the surface of spiked NPs, effectively reduces the length of spikes exposed to the interaction with lipid bilayers. Thus, protein corona changes qualitatively the dynamics of pore formation, which is completely suppressed at high protein concentrations. These results suggest that protein corona can not only be critical for interaction of NPs with membranes, it may change their mode of interaction, thus offsetting the role of surface chemistry and ligands.

Gene Therapy to Modulate Alpha-Synuclein in Synucleinopathies

The protein alpha-Synuclein (α-Syn) is a key contributor to the etiology of Parkinson’s disease (PD) with aggregation, trans-neuronal spread, and/or depletion of α-Syn being viewed as crucial events in the molecular processes that result in neurodegeneration. The exact succession of pathological occurrences that lead to neuronal death are still largely unknown and are likely to be multifactorial in nature. Despite this unknown, α-Syn dose and stability, autophagy-lysosomal dysfunction, and inflammation, amongst other cellular impairments, have all been described as participatory events in the neurodegenerative process. To that end, in this review we discuss the logical points for gene therapy to intervene in α-Syn-mediated disease and review the preclinical body of work where gene therapy has been used, or could conceptually be used, to ameliorate α-Syn induced neurotoxicity. We discuss gene therapy in the traditional sense of modulating gene expression, as well as the use of viral vectors and nanoparticles as methods to deliver other therapeutic modalities.

Alzheimer's disease-associated β-amyloid does not protect against herpes simplex virus 1 infection in the mouse brain

Alzheimer’s disease (AD) is a devastating fatal neurodegenerative disease. An alternative to the amyloid cascade hypothesis is that a viral infection is key to the etiology of late-onset AD, with β-amyloid (Aβ) peptides playing a protective role. In the current study, young 5XFAD mice that overexpress mutant human amyloid precursor protein with the Swedish, Florida, and London familial AD mutations were infected with one of two strains of herpes simplex virus 1 (HSV-1), 17syn+ and McKrae, at three different doses. Contrary to previous work, 5XFAD genotype failed to protect mice against HSV-1 infection. The region- and cell-specific tropisms of HSV-1 were not affected by the 5XFAD genotype, indicating that host–pathogen interactions were not altered. Seven- to ten-month-old 5XFAD animals in which extracellular Aβ aggregates were abundant showed slightly better survival rate relative to their wild-type (WT) littermates, although the difference was not statistically significant. In these 5XFAD mice, HSV-1 replication centers were partially excluded from the brain areas with high densities of Aβ aggregates. Aβ aggregates were free of HSV-1 viral particles, and the limited viral invasion to areas with a high density of Aβ aggregates was attributed to phagocytic activity of reactive microglia. In the oldest mice (12–15 months old), the survival rate did not differ between 5XFAD and WT littermates. While the current study questions the antiviral role of Aβ, it neither supports nor refutes the viral etiology hypothesis of late-onset AD.

Potential Virus Involvement in Alzheimer's Disease: Results from a Phase IIa Trial Evaluating Apovir, an Antiviral Drug Combination

Background:

Accumulating data suggest infectious agents are involved in Alzheimer’s disease (AD). The two primary aims of this trial were to assess safety and efficacy of an antiviral drug combination on AD progression.

Objective:

The trial evaluated whether Apovir, a combination of two antiviral agents, pleconaril (active on enteroviruses) and ribavirin (active on several viruses), could slow AD progression.

Methods:

Sixty-nine patients 60–85 years were treated with Apovir or placebo for 9 months and followed until 12 months after end of treatment. Cognitive tests, safety, biomarkers, drug plasma, and cerebrospinal fluid concentrations were assessed.

Results:

The tolerability of Apovir was compromised as demonstrated by the large drop-out rate and increased frequency and severity of adverse events. The primary endpoint, demonstrating a difference in change from baseline to 9 months between groups in ADAS-cog total score, was not met (p = 0.1809). However, there were observations indicating potential effects on both ADAS-cog and CDR-SB but these effects need to be verified. Also, there was a decrease in cerebrospinal fluid amyloid-β in Apovir at 9 months (p = 0.0330) but no change in placebo.

Conclusion:

This was the first randomized, placebo controlled clinical trial exploring antiviral treatment on AD progression. The trial is considered inconclusive due to the large drop-out rate. New trials are needed to verify if the indications of effect observed can be confirmed and which component(s) in Apovir contributed to such effects. Pleconaril alone may be studied to improve the tolerability and to verify if enterovirus is involved in the disease process.

Baseline Infection Burden and Cognitive Function in Elders with Essential Tremor

Background

Patients with essential tremor (ET) have an increased risk of cognitive impairment, yet little is known about the predictors of cognitive decline in these patients. Exposures to infectious agents throughout the lifespan may impact the later development of cognitive impairment. For example, high Infection exposure has been associated with lower cognitive performance in Alzheimer's and Parkinson's disease. However, this predictor has not been examined in ET.

Objectives

To determine whether a higher baseline infection burden is associated with worse cognitive performance at baseline and greater cognitive decline over time in an ET cohort.

Method/Design

160 elderly non-demented ET participants (80.0 ± 9.5 years) underwent an extensive cognitive evaluation at three time points. At baseline, participants completed an infection burden questionnaire (t-IBQ) that elicited information on previous exposure to infectious agents and number of episodes per disease. Analysis of covariance and generalized estimated equations (GEEs) were used.

Results

Overall, infection burden was not associated baseline cognitive performance. Adjusted GEE models for repeated measures yielded a significant time interaction between moderate infection burden at baseline and better performance in the attention domain over time (p = 0.013). Previous history of rubella was associated with faster rate of decline in visuospatial performance (p = 0.046).

Conclusion

The data were mixed. Moderate self-reported infection burden was associated with better attention performance over time. Self-reported history of rubella infection was related to lower visuospatial performance over time in this cohort. Follow-up studies with additional design elements would be of value.

Underlying Mechanisms for the Modulation of Self-Assembly and the Intrinsic Fluorescent Properties of Amino Acid-Functionalized Gold Nanoparticles

The origin of the blue fluorescence of proteins and peptides in the visible region has been a subject of intense debate despite several efforts. Although aromatic amino acids, namely tryptophan (Trp), tyrosine (Tyr), and phenylalanine (Phe) are responsible for the intrinsic luminescence of proteins and peptides, the underlying mechanism and contributions of these amino acids to the unusual blue fluorescence are still not well resolved. In the present endeavor, we show that the clusterization of both aromatic and aliphatic amino acids on the surface of the gold nanoparticles (Au NPs) leads to clusteroluminescence, which could be linked to the unusual fluorescence properties of the proteins and peptides and have been ignored in the past. The amino acid monomers initially form small aggregates through clusterization, which provides the fundamental building blocks to establish the amyloid structure as well as the luminescence property. Because of the clusterization, these Au NPs/nano-aggregate systems are also found to exhibit remarkable stability against the freeze-thaw cycle and several other external stimuli, which can be useful for biological and biomedical applications.

SARS-CoV-2 spike protein interactions with amyloidogenic proteins: Potential clues to neurodegeneration

The post-infection of COVID-19 includes a myriad of neurologic symptoms including neurodegeneration. Protein aggregation in brain can be considered as one of the important reasons behind the neurodegeneration. SARS-CoV-2 Spike S1 protein receptor binding domain (SARS-CoV-2 S1 RBD) binds to heparin and heparin binding proteins. Moreover, heparin binding accelerates the aggregation of the pathological amyloid proteins present in the brain. In this paper, we have shown that the SARS-CoV-2 S1 RBD binds to a number of aggregation-prone, heparin binding proteins including Aβ, α-synuclein, tau, prion, and TDP-43 RRM. These interactions suggests that the heparin-binding site on the S1 protein might assist the binding of amyloid proteins to the viral surface and thus could initiate aggregation of these proteins and finally leads to neurodegeneration in brain. The results will help us to prevent future outcomes of neurodegeneration by targeting this binding and aggregation process.

Mechanisms and therapeutic potential of interactions between human amyloids and viruses

The aggregation of specific proteins and their amyloid deposition in affected tissue in disease has been studied for decades assuming a sole pathogenic role of amyloids. It is now clear that amyloids can also encode important cellular functions, one of which involves the interaction potential of amyloids with microbial pathogens, including viruses. Human expressed amyloids have been shown to act both as innate restriction molecules against viruses as well as promoting agents for viral infectivity. The underlying molecular driving forces of such amyloid-virus interactions are not completely understood. Starting from the well-described molecular mechanisms underlying amyloid formation, we here summarize three non-mutually exclusive hypotheses that have been proposed to drive amyloid-virus interactions. Viruses can indirectly drive amyloid depositions by affecting upstream molecular pathways or induce amyloid formation by a direct interaction with the viral surface or specific viral proteins. Finally, we highlight the potential of therapeutic interventions using the sequence specificity of amyloid interactions to drive viral interference.

Does COVID-19 contribute to development of neurological disease?

BACKGROUND

Although coronavirus disease 2019 (COVID-19) has been associated primarily with pneumonia, recent data show that the causative agent of COVID-19, the coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), can infect a large number of vital organs beyond the lungs, such as the heart, kidneys, and the brain. Thus, there is evidence showing possible retrograde transmission of the virus from the olfactory epithelium to regions of the brain stem.

METHODS

This is a literature review article. The research design method is an evidence-based rapid review. The present discourse aim is first to scrutinize and assess the available literature on COVID-19 repercussion on the central nervous system (CNS). Standard literature and database searches were implemented, gathered relevant material, and extracted information was then assessed.

RESULTS

The angiotensin-converting enzyme 2 (ACE2) receptors being the receptor for the virus, the threat to the central nervous system is expected. Neurons and glial cells express ACE2 receptors in the CNS, and recent studies suggest that activated glial cells contribute to neuroinflammation and the devastating effects of SARS-CoV-2 infection on the CNS. The SARS-CoV-2-induced immune-mediated demyelinating disease, cerebrovascular damage, neurodegeneration, and depression are some of the neurological complications discussed here.

CONCLUSION

This review correlates present clinical manifestations of COVID-19 patients with possible neurological consequences in the future, thus preparing healthcare providers for possible future consequences of COVID-19.

Heterotypic interactions in amyloid function and disease

Amyloid aggregation results from the self-assembly of identical aggregation-prone sequences into cross-beta-sheet structures. The process is best known for its association with a wide range of human pathologies but also as a functional mechanism in all kingdoms of life. Less well elucidated is the role of heterotypic interactions between amyloids and other proteins and macromolecules and how this contributes to disease. We here review current data with a focus on neurodegenerative amyloid-associated diseases. Evidence indicates that heterotypic interactions occur in a wide range of amyloid processes and that these interactions modify fundamental aspects of amyloid aggregation including seeding, aggregation rates and toxicity. More work is required to understand the mechanistic origin of these interactions, but current understanding suggests that both supersaturation and sequence-specific binding can contribute to heterotypic amyloid interactions. Further unravelling these mechanisms may help to answer outstanding questions in the field including the selective vulnerability of cells types and tissues and the stereotypical spreading patterns of amyloids in disease.

Biomedical nanoparticle design: What we can learn from viruses

Viruses are nanomaterials with a number of properties that surpass those of many synthetic nanoparticles (NPs) for biomedical applications. They possess a rigorously ordered structure, come in a variety of shapes, and present unique surface elements, such as spikes. These attributes facilitate propitious biodistribution, the crossing of complex biological barriers and a minutely coordinated interaction with cells. Due to the orchestrated sequence of interactions of their stringently arranged particle corona with cellular surface receptors they effectively identify and infect their host cells with utmost specificity, while evading the immune system at the same time. Furthermore, their efficacy is enhanced by their response to stimuli and the ability to spread from cell to cell. Over the years, great efforts have been made to mimic distinct viral traits to improve biomedical nanomaterial performance. However, a closer look at the literature reveals that no comprehensive evaluation of the benefit of virus-mimetic material design on the targeting efficiency of nanomaterials exists. In this review we, therefore, elucidate the impact that viral properties had on fundamental advances in outfitting nanomaterials with the ability to interact specifically with their target cells. We give a comprehensive overview of the diverse design strategies and identify critical steps on the way to reducing them to practice. More so, we discuss the advantages and future perspectives of a virus-mimetic nanomaterial design and try to elucidate if viral mimicry holds the key for better NP targeting.

Tutankhamun's Antimalarial Drug for Covid-19

Drug repositioning is a strategy that identifies new uses of approved drugs to treat conditions different from their original purpose. Current efforts to treat Covid-19 are based on this strategy. The first drugs used in patients infected with SARS-CoV-2 were antimalarial drugs. It is their mechanism of action, i. e., rise in endosomal pH, which recommends them against the new coronavirus. Disregarding their side effects, the study of their antiviral activity provides valuable hints for the choice and design of drugs against SARS-CoV-2. One prominent drug candidate is thymoquinone, an antimalarial substance contained in Nigella sativa - most likely one of the first antimalarial drugs in human history. Since the outbreak of the pandemic, the number of articles relating thymoquinone to Covid-19 continuously increases. Here, we use it as an exemplary model drug, compare its antiviral mechanism with that of conventional antimalarial drugs and establish an irreducible parametric scheme for the identification of drugs with a potential in Covid-19.Translation into the laboratory is simple. Starting with the discovery of Nigella sativa seeds in the tomb of Pharaoh Tutankhamun, we establish a physicochemical model for the interaction of thymoquinone with both coronavirus and cells. Exploiting the predictive capability of the model, we provide a generalizable scheme for the systematic choice and design of drugs for Covid-19. An unexpected offshoot of our research is that Tutankhamun could not have died of malaria, a finding contrary to the mainstream theory.