The Proteome and Secretome of Cortical Brain Cells Infected With Herpes Simplex Virus

bootGSEA: a bootstrap and rank aggregation pipeline for multi-study and multi-omics enrichment analyses

Introduction: Gene set enrichment analysis (GSEA) subsequent to differential expression analysis is a standard step in transcriptomics and proteomics data analysis. Although many tools for this step are available, the results are often difficult to reproduce because set annotations can change in the databases, that is, new features can be added or existing features can be removed. Finally, such changes in set compositions can have an impact on biological interpretation. Methods: We present bootGSEA, a novel computational pipeline, to study the robustness of GSEA. By repeating GSEA based on bootstrap samples, the variability and robustness of results can be studied. In our pipeline, not all genes or proteins are involved in the different bootstrap replicates of the analyses. Finally, we aggregate the ranks from the bootstrap replicates to obtain a score per gene set that shows whether it gains or loses evidence compared to the ranking of the standard GSEA. Rank aggregation is also used to combine GSEA results from different omics levels or from multiple independent studies at the same omics level. Results: By applying our approach to six independent cancer transcriptomics datasets, we showed that bootstrap GSEA can aid in the selection of more robust enriched gene sets. Additionally, we applied our approach to paired transcriptomics and proteomics data obtained from a mouse model of spinal muscular atrophy (SMA), a neurodegenerative and neurodevelopmental disease associated with multi-system involvement. After obtaining a robust ranking at both omics levels, both ranking lists were combined to aggregate the findings from the transcriptomics and proteomics results. Furthermore, we constructed the new R-package "bootGSEA," which implements the proposed methods and provides graphical views of the findings. Bootstrap-based GSEA was able in the example datasets to identify gene or protein sets that were less robust when the set composition changed during bootstrap analysis. Discussion: The rank aggregation step was useful for combining bootstrap results and making them comparable to the original findings on the single-omics level or for combining findings from multiple different omics levels.

Temporal pathway analysis of cerebrospinal fluid proteome in herpes simplex encephalitis

OBJECTIVES

We examined the temporal changes of the CSF proteome in patients with herpes simplex encephalitis (HSE) during the course of the disease, in relation to anti-N-methyl-D-aspartate receptor (NMDAR) serostatus, corticosteroid treatment, brain MRI and neurocognitive performance.

METHODS

Patients were retrospectively included from a previous prospective trial with a pre-specified CSF sampling protocol. Mass spectrometry data of the CSF proteome were processed using pathway analysis.

RESULTS

We included 48 patients (110 CSF samples). Samples were grouped based on time of collection relative to hospital admission - T1: ≤ 9 d, T2: 13-28 d, T3: ≥ 68 d. At T1, a strong multi-pathway response was seen including acute phase response, antimicrobial pattern recognition, glycolysis and gluconeogenesis. At T2, most pathways activated at T1 were no longer significantly different from T3. After correction for multiplicity and considering the effect size threshold, 6 proteins were significantly less abundant in anti-NMDAR seropositive patients compared to seronegative: procathepsin H, heparin cofactor 2, complement factor I, protein AMBP, apolipoprotein A1 and polymeric immunoglobulin receptor. No significant differences in individual protein levels were found in relation to corticosteroid treatment, size of brain MRI lesion or neurocognitive performance.

CONCLUSIONS

We show a temporal change in the CSF proteome in HSE patients during the course of the disease. This study provides insight into quantitative and qualitative aspects of the dynamic pathophysiology and pathway activation patterns in HSE and prompts for future studies on the role of apolipoprotein A1 in HSE, which has previously been associated with NMDAR encephalitis.

NEK7: a new target for the treatment of multiple tumors and chronic inflammatory diseases

NIMA-related kinase 7 (NEK7) is a serine/threonine kinase, which is the smallest one in mammalian NEK family. At present, many studies have reported that NEK7 has a physiological role in regulating the cell cycle and promoting the mitotic process of cells. In recent years, an increasing number of studies have proposed that NEK7 is involved in the activation of the NLRP3 inflammasome. Under normal conditions, NEK7 is in a low activity state, while under pathological conditions, NEK7 is abnormally expressed and therefore plays a key role in the progression of multiple tumors and chronic inflammatory diseases. This review will concentrate on the mechanism of NEK7 participates in the process of mitosis and regulates the activation of NLRP3 inflammasome, the aberrant expression of NEK7 in a variety of tumors and chronic inflammatory diseases, and some potential inhibitors, which may provide some new ideas for the treatment of diverse tumors and chronic inflammatory diseases associated with NEK7.

SUN2 Modulates the Propagation of HSV-1

Herpesviruses assemble new viral particles in the nucleus. These nucleocapsids bud through the inner nuclear membrane to produce enveloped viral particles in the perinuclear space before fusing with the outer nuclear membrane to reach the cytoplasm. This unusual route is necessary since viral capsids are too large to pass through nuclear pores. However, the transient perinuclear nucleocapsids (250 nm in diameter) are also larger than the width of the perinuclear space (30 to 50 nm). Interestingly, linker of the nucleoskeleton and cytoskeleton (LINC) components SUN and KASH connect the inner and outer nuclear membranes and regulate their spacing. Previous work by others on the related pseudorabies virus and human cytomegalovirus showed that they functionally interact with SUN proteins. To clarify the role of SUN proteins, we explored their impact on herpes simplex virus 1 (HSV-1), another herpesvirus. Using dominant negative SUN mutants and RNA interference, we show that HSV-1 propagation is dependent on the LINC complex. In contrast to pseudorabies virus, SUN2 disruption by either approach led to increased HSV-1 extracellular viral yields. This SUN2 dependency may be linked to its greater impact on perinuclear spacing in infected cells compared to SUN1. Finally, the virus itself seems to modulate perinuclear spacing. IMPORTANCE The large size of herpesviruses prevents them from travelling across the nuclear pores, and they instead egress across the two nuclear membranes, generating short-lived enveloped perinuclear virions. This poses a challenge as the perinuclear space is smaller than the virions. This implies the separation (unzipping) of the two nuclear membranes to accommodate the viral particles. The LINC complex bridges the two nuclear membranes and is an important regulator of perinuclear spacing. Work by others hint at its functional implication during pseudorabies virus and cytomegalovirus propagation. The present study probes the importance for HSV-1 of the SUN proteins, the LINC components found in the inner nuclear membrane. Using dominant negative constructs and RNA interference (RNAi), the data reveal that SUN2 exhibits antiviral propriety toward HSV-1, as disrupting the protein leads to increased viral yields. This is in contrast with that reported for pseudorabies and suggests that differences among herpesviruses may, once again, prevail.

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.

Proteomic analysis of the secretome of equine herpesvirus-1 infected rabbit kidney cells

Herpesviruses are the main cause of abortions and respiratory or neurological disorders in horses. Various disease patterns are suspected to be associated with the A2254G point mutation in the DNA polymerase sequence (ORF30) of the herpesvirus genome, although the importance of this link is still under debate. Based on a label-free quantitative proteomic analysis, the differences in the secretion of some host proteins between rabbit kidney cells infected with A₂₂₅₄ and cells of the same line infected with G₂₂₅₄ equine herpesvirus 1 (EHV-1) strains were identified. In both groups, downregulation of proteins involved in insulin growth factor and extracellular matrix pathway regulation was observed. Among 12 proteins with increased secretion, 8 were regulated only in G₂₂₅₄ EHV-1 infection. Those were endoplasmic reticulum chaperones with calcium binding properties, related to unfolded protein response and mitochondria. It was presumed that the secretion of proteins such as calreticulin, Hspa5 or endoplasmin may contribute to the pathogenesis of EHV-1 infection.

Targeting Impaired Antimicrobial Immunity in the Brain for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia and aging is the most common risk factor for developing the disease. The etiology of AD is not known but AD may be considered as a clinical syndrome with multiple causal pathways contributing to it. The amyloid cascade hypothesis, claiming that excess production or reduced clearance of amyloid-beta (Aβ) and its aggregation into amyloid plaques, was accepted for a long time as the main cause of AD. However, many studies showed that Aβ is a frequent consequence of many challenges/pathologic processes occurring in the brain for decades. A key factor, sustained by experimental data, is that low-grade infection leading to production and deposition of Aβ, which has antimicrobial activity, precedes the development of clinically apparent AD. This infection is chronic, low grade, largely clinically silent for decades because of a nearly efficient antimicrobial immune response in the brain. A chronic inflammatory state is induced that results in neurodegeneration. Interventions that appear to prevent, retard or mitigate the development of AD also appear to modify the disease. In this review, we conceptualize further that the changes in the brain antimicrobial immune response during aging and especially in AD sufferers serve as a foundation that could lead to improved treatment strategies for preventing or decreasing the progression of AD in a disease-modifying treatment.

Interrogating Host Antiviral Environments Driven by Nuclear DNA Sensing: A Multiomic Perspective

Nuclear DNA sensors are critical components of the mammalian innate immune system, recognizing the presence of pathogens and initiating immune signaling. These proteins act in the nuclei of infected cells by binding to foreign DNA, such as the viral genomes of nuclear-replicating DNA viruses herpes simplex virus type 1 (HSV-1) and human cytomegalovirus (HCMV). Upon binding to pathogenic DNA, the nuclear DNA sensors were shown to initiate antiviral cytokines, as well as to suppress viral gene expression. These host defense responses involve complex signaling processes that, through protein–protein interactions (PPIs) and post-translational modifications (PTMs), drive extensive remodeling of the cellular transcriptome, proteome, and secretome to generate an antiviral environment. As such, a holistic understanding of these changes is required to understand the mechanisms through which nuclear DNA sensors act. The advent of omics techniques has revolutionized the speed and scale at which biological research is conducted and has been used to make great strides in uncovering the molecular underpinnings of DNA sensing. Here, we review the contribution of proteomics approaches to characterizing nuclear DNA sensors via the discovery of functional PPIs and PTMs, as well as proteome and secretome changes that define a host antiviral environment. We also highlight the value of and future need for integrative multiomic efforts to gain a systems-level understanding of DNA sensors and their influence on epigenetic and transcriptomic alterations during infection.