Recombinant human plasma gelsolin reverses increased permeability of the blood-brain barrier induced by the spike protein of the SARS-CoV-2 virus

Extracellular vimentin is a damage-associated molecular pattern protein serving as an agonist of TLR4 in human neutrophils

BACKGROUND

Vimentin is a type III intermediate filament protein that plays an important role in cytoskeletal mechanics. It is now known that vimentin also has distinct functions outside the cell. Recent studies show the controlled release of vimentin into the extracellular environment, where it functions as a signaling molecule. Such observations are expanding our current knowledge of vimentin as a structural cellular component towards additional roles as an active participant in cell signaling.

METHODS

Our study investigates the immunological roles of extracellular vimentin (eVim) and its citrullinated form (CitVim) as a damage-associated molecular pattern (DAMP) engaging the Toll-like receptor 4 (TLR4) of human neutrophils. We used in vitro assays to study neutrophil migration through endothelial cell monolayers and activation markers such as NADPH oxidase subunit 2 (NOX2/gp91phox). The comparison of eVim with CitVim and its effect on human neutrophils was extended to the induction of extracellular traps (NETs) and phagocytosis of pathogens.

RESULTS

Both eVim and CitVim interact with and trigger TLR4, leading to increased neutrophil migration and adhesion. CitVim stimulated the enhanced migratory ability of neutrophils, activation of NF-κB, and induction of NET formation mainly mediated through reactive oxygen species (ROS)-dependent and TLR4-dependent pathways. In contrast, neutrophils exposed to non-citrullinated vimentin exhibited higher efficiency in favoring pathogen phagocytosis, such as Escherichia coli and Candida albicans, compared to CitVim.

CONCLUSIONS

Our study identifies new functions of eVim in its native and modified forms as an extracellular matrix DAMP and highlights its importance in the modulation of immune system functions. The differential effects of eVim and CitVim on neutrophil functions highlight their potential as new molecular targets for therapeutic strategies aimed at regulation of neutrophil activity in different pathological conditions. This, in turn, opens new windows of therapeutic intervention in inflammatory and immunological diseases characterized by immune system dysfunction, in which eVim and CitVim play a key role.

Modular cone-and-plate device for mechanofluidic assays in Transwell inserts

In this work, we present a cost effective and open-source modular cone-and-plate (MoCAP) device that incorporates shear stress in the popular Transwell® insert system. This system acts as a lid that incorporates flow into 24-well Transwell® inserts while preserving the ability to conduct molecular profiling assays. Moreover, the MoCAP device can be rapidly reconfigured to test multiple shear stress profiles within a single device. To demonstrate the utility of the MoCAP, we conducted select assays on several different brain microvascular endothelial cell (BMEC) lines that comprise models of the blood-brain barrier (BBB), since shear stress can play an important role in BBB function. Our results characterize how shear stress modulates passive barrier function and GLUT1 expression across the different BMEC lines. Overall, we anticipate this low cost mechanofluidic device will be useful to the mechanobiology community.

An integrated bioinformatics approach reveals the potential role of microRNA-30b-5p and let-7a-5p during SARS CoV-2 spike-1 mediated neuroinflammation

SARS-CoV-2 induced neuroinflammation contributing to neurological sequelae is one of the critical outcomes of long-COVID, however underlying regulatory mechanisms involved therein are poorly understood. We deciphered the profile of dysregulated microRNAs, their targets, associated pathways, protein-protein interactions (PPI), transcription factor-hub genes interaction networks, hub genes-microRNA co-regulatory networks in SARS-CoV-2 Spike-1 (S1) stimulated microglial cells along with candidate drug prediction using RNA-sequencing and multiple bioinformatics approaches. We identified 11 dysregulated microRNAs in the S1-stimulated microglial cells (p < 0.05). KEGG analysis revealed involvement of important neuroinflammatory pathways such as MAPK signalling, PI3K-AKT signalling, Ras signalling and axon guidance. PPI analysis further identified 11 hub genes involved in these pathways. Real time PCR validation confirmed a significant upregulation of microRNA-30b-5p and let-7a-5p; proinflammatory cytokines- IL-6, TNF-α, IL-1β, GM-CSF; and inflammatory genes- PIK3CA and AKT in the S1-stimulated microglial cells, while PTEN and SHIP1 expression was decreased as compared to the non-stimulated cells. Drug prediction analysis further indicated resveratrol, diclofenac and rapamycin as the potential drugs based on their degree of interaction with hub genes. Thus, targeting of these microRNAs and/or their intermediate signalling molecules would be a prospective immunotherapeutic approach in alleviating SARS-CoV-2-S1 mediated neuroinflammation; and needs further investigations.

Acute severe hypoglycemia alters mouse brain microvascular proteome

Hypoglycemia increases the risk related to stroke and neurodegenerative diseases, however, the underlying mechanisms are unclear. For the first time, we studied the effect of a single episode (acute) of severe (ASH) and mild (AMH) hypoglycemia on mouse brain microvascular proteome. After four-hour fasting, insulin was administered (i.p) to lower mean blood glucose in mice and induce ∼30 minutes of ASH (∼30 mg/dL) or AMH (∼75 mg/dL), whereas a similar volume of saline was given to control mice (∼130 mg/dL). Blood glucose was allowed to recover over 60 minutes either spontaneously or by 20% dextrose administration (i.p). Twenty-four hours later, the brain microvessels (BMVs) were isolated, and tandem mass tag (TMT)-based quantitative proteomics was performed using liquid chromatography-mass spectrometry (LC/MS). When compared to control, ASH significantly downregulated 13 proteins (p ≤ 0.05) whereas 23 proteins showed a strong trend toward decrease (p ≤ 0.10). When compared to AMH, ASH significantly induced the expression of 35 proteins with 13 proteins showing an increasing trend. AMH downregulated only 3 proteins. ASH-induced downregulated proteins are involved in actin cytoskeleton maintenance needed for cell shape and migration which are critical for blood-brain barrier maintenance and angiogenesis. In contrast, ASH-induced upregulated proteins are RNA-binding proteins involved in RNA splicing, transport, and stability. Thus, ASH alters BMV proteomics to impair cytoskeletal integrity and RNA processing which are critical for cerebrovascular function.

The S1 subunits of SARS-CoV-2 variants differentially trigger the IL-6 signaling pathway in human brain endothelial cells and downstream impact on microglia activation

Objectives

Cerebrovascular complications are prevalent in COVID-19 infection and post-COVID conditions; therefore, interactions of SARS-CoV-2 with cerebral microvascular cells became an emerging concern.

Methods

We examined the inflammatory responses of human brain microvascular endothelial cells (HBMEC), the main structural element of the blood-brain barrier (BBB), following exposure to the S1 subunit of the spike protein of different SARS-CoV-2 variants. Specifically, we used the S1 subunit derived from the D614 variant of SARS-CoV-2, which started widely circulating in March of 2020, and from the Delta variant, which started widely circulating in early 2021. We then further examined the impact of the HBMEC secretome, produced in response to the S1 exposure, on microglial proinflammatory responses.

Results

Treatment with S1 derived from the D614 variant and from the Delta variant resulted in differential alterations of the IL-6 signaling pathway. Moreover, the HBMEC secretome obtained after exposure to the S1 subunit of the D614 variant activated STAT3 in microglial cells, indicating that proinflammatory signals from endothelial cells can propagate to other cells of the neurovascular unit. Overall, these results indicate the potential for different SARS-CoV-2 variants to induce unique cellular signatures and warrant individualized treatment strategies. The findings from this study also bring further awareness to proinflammatory responses involving brain microvasculature in COVID-19 and demonstrate how the surrounding microglia react to each unique variant derived response.

Protein profiling and assessment of amyloid beta levels in plasma in canine refractory epilepsy

Introduction

The relationship between epilepsy and cognitive dysfunction has been investigated in canines, and memory impairment was prevalent in dogs with epilepsy. Additionally, canines with epilepsy have greater amyloid-β (Aβ) accumulation and neuronal degeneration than healthy controls. The present study investigated plasma Aβ42 levels and performed proteomic profiling in dogs with refractory epilepsy and healthy dogs.

Methods

In total, eight dogs, including four healthy dogs and four dogs with epilepsy, were included in the study. Blood samples were collected to analyze Aβ42 levels and perform proteomic profiling. Changes in the plasma proteomic profiles of dogs were determined by nano liquid chromatography tandem mass spectrometry.

Results and discussion

The plasma Aβ42 level was significantly higher in dogs with epilepsy (99 pg/mL) than in healthy dogs (5.9 pg/mL). In total, 155 proteins were identified, and of these, the expression of 40 proteins was altered in epilepsy. Among these proteins, which are linked to neurodegenerative diseases, 10 (25%) were downregulated in dogs with epilepsy, whereas 12 (30%) were upregulated. The expression of the acute phase proteins haptoglobin and α2-macroglobulin significantly differed between the groups. Complement factor H and ceruloplasmin were only detected in epilepsy dogs, suggesting that neuroinflammation plays a role in epileptic seizures. Gelsolin, which is involved in cellular processes and cytoskeletal organization, was only detected in healthy dogs. Gene Ontology annotation revealed that epilepsy can potentially interfere with biological processes, including cellular processes, localization, and responses to stimuli. Seizures compromised key molecular functions, including catalytic activity, molecular function regulation, and binding. Defense/immunity proteins were most significantly modified during the development of epilepsy. In Kyoto Encyclopedia of Genes and Genomes pathway analysis, complement and coagulation cascades were the most relevant signaling pathways affected by seizures. The findings suggested that haptoglobin, ceruloplasmin, α2-macroglobulin, complement factor H, and gelsolin play roles in canine epilepsy and Aβ levels based on proteomic profiling. These proteins could represent diagnostic biomarkers that, after clinical validation, could be used in veterinary practice as well as proteins relevant to disease response pathways. To determine the precise mechanisms underlying these relationships and their implications in canine epilepsy, additional research is required.

Negative regulation of angiogenesis and the MAPK pathway may be a shared biological pathway between IS and epilepsy

Ischemia stroke and epilepsy are two neurological diseases that have significant patient and societal burden, with similar symptoms of neurological deficits. However, the underlying mechanism of their co-morbidity are still unclear. In this study, we performed a combined analysis of six gene expression profiles (GSE58294, GSE22255, GSE143272, GSE88723, GSE163654, and GSE174574) to reveal the common mechanisms of IS and epilepsy. In the mouse datasets, 74 genes were co-upregulated and 7 genes were co-downregulated in the stroke and epilepsy groups. Further analysis revealed that the co-expressed differentially expressed genes (DEGs) were involved in negative regulation of angiogenesis and the MAPK signaling pathway, and this was verified by Gene Set Enrichment Analysis of human datasets and single cell RNA sequence of middle cerebral artery occlusion mice. In addition, combining DEGs of human and mouse, PTGS2, TMCC3, KCNJ2, and GADD45B were identified as cross species conserved hub genes. Meanwhile, molecular docking results revealed that trichostatin A and valproic acid may be potential therapeutic drugs. In conclusion, to our best knowledge, this study conducted the first comorbidity analysis of epilepsy and ischemic stroke to identify the potential common pathogenic mechanisms and drugs. The findings may provide an important reference for the further studies on post-stroke epilepsy.

SARS-CoV-2 Structural Proteins Modulated Blood-Testis Barrier-Related Proteins through Autophagy in the Primary Sertoli Cells

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) disrupts the blood-testis barrier (BTB), resulting in alterations in spermatogenesis. However, whether BTB-related proteins (such as ZO-1, claudin11, N-cadherin, and CX43) are targeted by SARS-CoV-2 remains to be clarified. BTB is a physical barrier between the blood vessels and the seminiferous tubules of the animal testis, and it is one of the tightest blood-tissue barriers in the mammalian body. In this study, we investigated the effects of viral proteins, via ectopic expression of individual viral proteins, on BTB-related proteins, the secretion of immune factors, and the formation and degradation of autophagosomes in human primary Sertoli cells. Our study demonstrated that ectopic expression of viral E (envelope protein) and M (membrane protein) induced the expressions of ZO-1 and claudin11, promoted the formation of autophagosomes, and inhibited autophagy flux. S (spike protein) reduced the expression of ZO-1, N-cadherin, and CX43, induced the expression of claudin11, and inhibited the formation and degradation of autophagosomes. N (nucleocapsid protein) reduced the expression of ZO-1, claudin11, and N-cadherin. All the structural proteins (SPs) E, M, N, and S increased the expression of the FasL gene, and the E protein promoted the expression and secretion of FasL and TGF-β proteins and the expression of IL-1. Blockage of autophagy by specific inhibitors resulted in the suppression of BTB-related proteins by the SPs. Our results indicated that SARS-CoV-2 SPs (E, M, and S) regulate BTB-related proteins through autophagy.

Towards Novel Biomimetic In Vitro Models of the Blood-Brain Barrier for Drug Permeability Evaluation

Current available animal and in vitro cell-based models for studying brain-related pathologies and drug evaluation face several limitations since they are unable to reproduce the unique architecture and physiology of the human blood-brain barrier. Because of that, promising preclinical drug candidates often fail in clinical trials due to their inability to penetrate the blood-brain barrier (BBB). Therefore, novel models that allow us to successfully predict drug permeability through the BBB would accelerate the implementation of much-needed therapies for glioblastoma, Alzheimer's disease, and further disorders. In line with this, organ-on-chip models of the BBB are an interesting alternative to traditional models. These microfluidic models provide the necessary support to recreate the architecture of the BBB and mimic the fluidic conditions of the cerebral microvasculature. Herein, the most recent advances in organ-on-chip models for the BBB are reviewed, focusing on their potential to provide robust and reliable data regarding drug candidate ability to reach the brain parenchyma. We point out recent achievements and challenges to overcome in order to advance in more biomimetic in vitro experimental models based on OOO technology. The minimum requirements that should be met to be considered biomimetic (cellular types, fluid flow, and tissular architecture), and consequently, a solid alternative to in vitro traditional models or animals.

Gender-specific dysregulations of nondifferentially expressed biomarkers of metastatic colon cancer

Colon cancer is a common cancer type in both sexes and its mortality rate increases at the metastatic stage. Most studies exclude nondifferentially expressed genes from biomarker analysis of metastatic colon cancers. The motivation of this study is to find the latent associations of the nondifferentially expressed genes with metastatic colon cancers and to evaluate the gender specificity of such associations. This study formulates the expression level prediction of a gene as a regression model trained for primary colon cancers. The difference between a gene's predicted and original expression levels in a testing sample is defined as its mqTrans value (model-based quantitative measure of transcription regulation), which quantitatively measures the change of the gene's transcription regulation in this testing sample. We use the mqTrans analysis to detect the messenger RNA (mRNA) genes with nondifferential expression on their original expression levels but differentially expressed mqTrans values between primary and metastatic colon cancers. These genes are referred to as dark biomarkers of metastatic colon cancer. All dark biomarker genes were verified by two transcriptome profiling technologies, RNA-seq and microarray. The mqTrans analysis of a mixed cohort of both sexes could not recover gender-specific dark biomarkers. Most dark biomarkers overlap with long non-coding RNAs (lncRNAs), and these lncRNAs might have contributed their transcripts to calculating the dark biomarkers' expression levels. Therefore, mqTrans analysis serves as a complementary approach to identify dark biomarkers generally ignored by conventional studies, and it is essential to separate the female and male samples into two analysis experiments. The dataset and mqTrans analysis code are available at https://figshare.com/articles/dataset/22250536.

Immune Response and Molecular Mechanisms of Cardiovascular Adverse Effects of Spike Proteins from SARS-CoV-2 and mRNA Vaccines

The SARS-CoV-2 (severe acute respiratory syndrome coronavirus responsible for the COVID-19 disease) uses the Spike proteins of its envelope for infecting target cells expressing on the membrane the angiotensin converting enzyme 2 (ACE2) enzyme that acts as a receptor. To control the pandemic, genetically engineered vaccines have been designed for inducing neutralizing antibodies against the Spike proteins. These vaccines do not act like traditional protein-based vaccines, as they deliver the message in the form of mRNA or DNA to host cells that then produce and expose the Spike protein on the membrane (from which it can be shed in soluble form) to alert the immune system. Mass vaccination has brought to light various adverse effects associated with these genetically based vaccines, mainly affecting the circulatory and cardiovascular system. ACE2 is present as membrane-bound on several cell types, including the mucosa of the upper respiratory and of the gastrointestinal tracts, the endothelium, the platelets, and in soluble form in the plasma. The ACE2 enzyme converts the vasoconstrictor angiotensin II into peptides with vasodilator properties. Here we review the pathways for immunization and the molecular mechanisms through which the Spike protein, either from SARS-CoV-2 or encoded by the mRNA-based vaccines, interferes with the Renin-Angiotensin-System governed by ACE2, thus altering the homeostasis of the circulation and of the cardiovascular system. Understanding the molecular interactions of the Spike protein with ACE2 and the consequent impact on cardiovascular system homeostasis will direct the diagnosis and therapy of the vaccine-related adverse effects and provide information for development of a personalized vaccination that considers pathophysiological conditions predisposing to such adverse events.