The proteome of Toll-like receptor 3-stimulated human immortalized fibroblasts: implications for susceptibility to herpes simplex virus encephalitis

Herpes Simplex Virus-2 Encephalitis Complicated with Multiple Cranial Neuritis and Dysautonomia

INTRODUCTION

Herpes simplex encephalitis (HSE) is mainly caused by herpes simplex virus-1 infection (HSV-1). Herpes simplex virus-2 (HSV-2) infection is rare except in neonates or the immune-compromised. Cranial neuritis is rarely reported in association with HSE. This case study in an eleven-month-old followed by a literature review on cranial neuritis in HSE in children is presented due to the rarity of both situations.

CASE REPORT

An eleven-month old otherwise healthy infant presented with encephalitis due to HSV-2 infection which was complicated with dysautonomia manifesting as blood pressure fluctuations and tachycardia, and cranial neuritis manifesting as unilateral ptosis and palatal palsy. The clinical presentation of brain stem encephalitis was confirmed by the Magnetic Resonance Imaging findings of hyperintense foci and contrast enhancement in the medulla oblongata. Following treatment with acyclovir, he made a complete recovery. He did not have any clinical or laboratorial evidence suggestive of immune deficiency.

CONCLUSION

HSV-2 infection can occur beyond the neonatal age group even in the absence of immune compromise. The brainstem encephalitis manifesting as cranial neuritis and autonomic dysfunction made a complete recovery.

Cytokines and chemokines expression pattern in herpes simplex virus type-1 encephalitis

To explore the differently expressed cytokines and chemokines to understand the pathways that lead to herpes simplex encephalitis (HSE). Mice in the experimental group were inoculated intracranially with HSV-1. A high-throughput cytokine chip assay was employed to assess the expression of cytokines/chemokines in the mice brain. GO, KEGG, and PPIs analyses were used to investigate the biological process (BP), pathways and interaction network of the differently expressed proteins (DEPs) in HSE. 13 DEPs and various proteins-related signal pathways were identified in HSE, including three new factors (IL-1α, MIP-1γ, and sTNF RI). The proteins were mainly implicated in leukocyte activation and chemotaxis. Additionally, the DEPs constituted a pivotal protein interaction network where IL-6 might be a mediator. 13 DEPs and a series of related signal pathways were associated with the pathophysiological mechanisms responsible for HSE. IL-6 might be a key mediator in the inflammatory responses to the disease.

Diminished toll-like receptor response in febrile infection-related epilepsy syndrome (FIRES)

Background

Defective human TLR3 signaling causes recurrent and refractory herpes simplex encephalitis/encephalopathy. Children with febrile infection-related epilepsy syndrome with refractory seizures may have defective TLR responses.

Methods

Children with febrile infection-related epilepsy syndrome were enrolled in this study to evaluate TLR1-9 responses (IL-6, IL-8, IL-12p40, INF-α, INF-γ, and TNF-α) in their peripheral blood mononuclear cells (PBMCs) and monocyte-derived dendritic cells (MDDCs), compared to those with febrile seizures and non-refractory epilepsy with/without underlying encephalitis/encephalopathy.

Results

Adenovirus and enterovirus were found in throat cultures of enrolled patients (2–13 years) as well as serologic IgM elevation of mycoplasma pneumonia and herpes simplex virus, although neither detectable pathogens nor anti-neural autoantibodies in the CSF could be noted. Their PBMCs and MDDCs trended to have impaired TLR responses and significantly lower in cytokine profiles of TLR3, TLR4, TLR7/8, and TLR9 responses but not other TLRs despite normal TLR expressions and normal candidate genes for defective TLR3 signaling. They also had decreased naïve T and T regulatory cells, and weakened phagocytosis.

Conclusion

Children with febrile infection-related epilepsy syndrome (FIRES) could have impaired TLR3, TLR4, TLR7/8, and TLR9 responses possibly relating to their weakened phagocytosis and decreased T regulatory cells.

Repeat exposure to polyinosinic:polycytidylic acid induces TLR3 expression via JAK-STAT signaling and synergistically potentiates NFκB-RelA signaling in ARPE-19 cells

Dry age-related macular degeneration (AMD), accounting for approximately 90% of AMD cases, is characterized by photoreceptor death, retinal pigment epithelium (RPE) dysfunction and, ultimately, geographic atrophy - the localized death of RPE leading to loss of the center of the visual field. The pathological etiology of AMD is multifactorial, but innate immune signaling and inflammation are involved in early stages of the disease. Although numerous single-nucleotide polymorphisms in innate immune genes are associated with dry AMD, no single gene appears to cause dry AMD. Here, we hypothesized that activation of TLR3 potentiates expression of TLR3 itself and the NFκB-p65 (RelA) subunit as part of pro-inflammatory RPE signaling. Furthermore, we hypothesized that TLR3 activation can 'prime' cells to future RelA stimulation, leading to enhanced, persistent RelA expression and signaling following a second TLR3 activation. We used the human RPE-derived cell line ARPE-19 as a model system for RPE signaling and measured NFκB expression and activity in response to TLR3 stimulation with its ligand, polyinosinic:polycytidylic acid (pI:C). Activation of TLR3 with pI:C led to increased TLR3 and RelA expression that was sustained for at least 24 h. Cells exposed for a second time to pI:C after an initial pI:C exposure displayed elevated RelA expression and RelA nuclear translocation above the level generated by individual primary or secondary exposures alone. Such an elevated response could also not be generated by a single application of higher concentrations of the agonist pI:C. Additionally, we determined the mechanism for TLR3 mediated TLR3 and RelA expression by using inhibitors of canonical TLR3-TBK1-IKKε and JAK-STAT signaling pathways. These data suggest that initial exposure of ARPE-19 cells to pI:C upregulates TLR3 and RelA signaling, leading to potentiated and persistent RelA signaling potentially generated by a positive feedback loop that may cause exacerbated inflammation in AMD. Furthermore, inhibition of JAK-STAT signaling may be a possible therapeutic treatment to prevent induction of TLR3 expression subsequent to pI:C exposure. Our results identify possible therapeutic targets to reduce the TLR3 positive feedback loop and subsequent overproduction of pro-inflammatory cytokines in RPE cells.

Herpes Simplex Encephalitis: an Update

PURPOSE OF REVIEW

The goal of this review is to provide an update on current thinking regarding herpes simplex encephalitis (HSE), emphasizing new information about pathogenesis, diagnosis, and immune responses. Specific questions to be addressed are the following: (1) Is there a genetic predisposition to HSE? (2) What clinical approaches have the greatest impact on improving the long-term outcomes in patients with HSE? And (3) are there immune-mediated mechanisms that may account for relapsing HSE?

RECENT FINDINGS

Toll-like receptor 3 (TLR 3) plays an important role in innate immune responses, including generation of interferons. Multiple single-gene errors in TLR 3 interferon pathways have recently been described in children that result in increased susceptibility to HSE. Conversely, studies in both animal models and humans indicate that both cytolytic viral replication and immune-mediated responses (including cytotoxic T lymphocytes and immune mechanisms mediated by TLR 2) contribute to the pathology of HSV, suggesting possible new therapeutic approaches. In terms of treatment, data clearly indicate that a longer duration between onset of symptoms and initiation of effective antiviral therapy correlates directly with less favorable clinical outcome. Recurrent or relapsing HSE may occasionally occur, but recent observations indicate that many instances of "relapsing HSE", especially in children, are more often anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis triggered by the antecedent HSV infection. Innate immune responses are critical for defense against HSV; genetic defects in this system may predispose patients to HSE. During acute HSE, exuberant immune responses may contribute to the CNS pathology, suggesting that selective immunosuppressive therapy, coupled with potent antiviral drugs, may eventually play a role in the therapeutic management of HSV. While overall clinical outcomes of HSE remain suboptimal, the initiation of high-dose acyclovir therapy as early as possible in the course of the illness provides the best chance for a patient to survive with minimal neurologic damage. Distinguishing relapsing HSE from autoimmune anti-NMDAR antibody encephalitis is critically important because therapeutic approaches will be very different.

Investigating the biology of alpha herpesviruses with MS-based proteomics

Viruses are intracellular parasites that can only replicate and spread in cells of susceptible hosts. Alpha herpesviruses (α-HVs) contain double-stranded DNA genomes of at least 120 kb, encoding for 70 or more genes. The viral genome is contained in an icosahedral capsid that is surrounded by a proteinaceous tegument layer and a lipid envelope. Infection starts in epithelial cells and spreads to the peripheral nervous system. In the natural host, α-HVs establish a chronic latent infection that can be reactivated and rarely spread to the CNS. In the nonnatural host, viral infection will in most cases spread to the CNS with often fatal outcome. The host response plays a crucial role in the outcome of viral infection. α-HVs do not encode all the genes required for viral replication and spread. They need a variety of host gene products including RNA polymerase, ribosomes, dynein, and kinesin. As a result, the infected cell is dramatically different from the uninfected cell revealing a complex and dynamic interplay of viral and host components required to complete the virus life cycle. In this review, we describe the pivotal contribution of MS-based proteomics studies over the past 15 years to understand the complicated life cycle and pathogenesis of four α-HV species from the alphaherpesvirinae subfamily: Herpes simplex virus-1, varicella zoster virus, pseudorabies virus and bovine herpes virus-1. We describe the viral proteome dynamics during host infection and the host proteomic response to counteract such pathogens.

Proteomics reveals the importance of the dynamic redistribution of the subcellular location of proteins in breast cancer cells

At the molecular level, living cells are enormously complicated complex adaptive systems in which intertwined genomic, transcriptomic, proteomic and metabolic networks all play a crucial role. At the same time, cells are spatially heterogeneous systems in which subcellular compartmentalization of different functions is ubiquitous and requires efficient cross-compartmental communication. Dynamic redistribution of multitudinous proteins to different subcellular locations in response to cellular functional state is increasingly recognized as a crucial characteristic of cellular function that seems to be at least as important as overall changes in protein abundance. Characterization of the subcellular spatial dynamics of protein distribution is a major challenge for proteomics and recent results with MCF7 breast cancer cells suggest that this may be of particular importance for cancer cells.

Advances in basic and clinical immunology in 2013

A significant number of contributions to our understanding of primary immunodeficiencies (PIDs) in pathogenesis, diagnosis, and treatment were published in the Journal in 2013. For example, deficiency of mast cell degranulation caused by signal transducer and activator of transcription 3 deficiency was demonstrated to contribute to the difference in the frequency of severe allergic reactions in patients with autosomal dominant hyper-IgE syndrome compared with that seen in atopic subjects with similar high IgE serum levels. High levels of nonglycosylated IgA were found in patients with Wiskott-Aldrich syndrome, and these abnormal antibodies might contribute to the nephropathy seen in these patients. New described genes causing immunodeficiency included caspase recruitment domain 11 (CARD11), mucosa-associated lymphoid tissue 1 (MALT1) for combined immunodeficiencies, and tetratricopeptide repeat domain 7A (TTC7A) for mutations associated with multiple atresia with combined immunodeficiency. Other observations expand the spectrum of clinical presentation of specific gene defects (eg, adult-onset idiopathic T-cell lymphopenia and early-onset autoimmunity might be due to hypomorphic mutations of the recombination-activating genes). Newborn screening in California established the incidence of severe combined immunodeficiency at 1 in 66,250 live births. The use of hematopoietic stem cell transplantation for PIDs was reviewed, with recommendations to give priority to research oriented to establish the best regimens to improve the safety and efficacy of bone marrow transplantation. These represent only a fraction of significant research done in patients with PIDs that has accelerated the quality of care of these patients. Genetic analysis of patients has demonstrated multiple phenotypic expressions of immune deficiency in patients with nearly identical genotypes, suggesting that additional genetic factors, possibly gene dosage, or environmental factors are responsible for this diversity.

Proteomics in immunity and herpes simplex encephalitis

The genetic theory of infectious diseases has proposed that susceptibility to life-threatening infectious diseases in childhood, occurring in the course of primary infection, results mostly from individually rare but collectively diverse single-gene variants. Recent evidence of an ever-expanding spectrum of genes involved in susceptibility to infectious disease indicates that the paradigm has important implications for diagnosis and treatment. One such pathology is childhood herpes simplex encephalitis, which shows a pattern of rare but diverse disease-disposing genetic variants. The present report shows how proteomics can help to understand susceptibility to childhood herpes simplex encephalitis and other viral infections, suggests that proteomics may have a particularly important role to play, emphasizes that variation over the population is a critical issue for proteomics and notes some new challenges for proteomics and related bioinformatics tools in the context of rare but diverse genetic defects.

Recent issues in herpes simplex encephalitis

Herpes simplex encephalitis (HSE) remains the most important cause of fatal sporadic encephalitis in man. Caused by herpes simplex virus type 1 (HSV-1), and more rarely by HSV-2, it can have devastating clinical consequences for the patient, especially when the instigation of acyclovir therapy has been delayed by more than 2 days or more. Even with acyclovir treatment, nearly a third of patients may die or suffer significant morbidity. Both host and viral factors may interact to affect the clinical phenotype. Here we consider some of the recently published management guidelines for HSE and comment on various current issues of contention. The latter includes the timing and frequency of cerebrospinal fluid examinations for the polymerase chain reaction detection of HSV, decisions regarding acyclovir therapy including the consequences of delay in its initiation, and the use of corticosteroids in the disease.