Elevated cerebrospinal fluid IgG index in herpes simplex encephalitis post-HSV-1 clearance: A preliminary study.

Herpes simplex encephalitis (HSE) is an acute form of encephalitis that can lead to poor neurological outcomes. Although the exact pathogenesis of HSE remains elusive, recent reports suggest a significant role for postinfectious immune-inflammatory processes in the central nervous system (CNS). This study aimed to clarify the association between CNS autoimmune responses and clinical presentation in patients with HSE, focusing on cerebrospinal fluid (CSF) characteristics, particularly the IgG index. We retrospectively analyzed 176 consecutive patients suspected of having aseptic meningitis /encephalitis for chronological changes in CSF findings and clinical presentations. These patients underwent PCR screening for herpesviruses (HV) in their CSF. We identified seven patients positive for herpes simplex virus type 1 (HSV-1), 20 patients positive for varicella-zoster virus, and 17 patients who met the criteria for aseptic meningitis but were PCR-negative for HV. Patients in the HSV-1-positive group exhibited a significant increase in the IgG index at the time of PCR-negative conversion compared with on admission (p = 0.0156), while such a change was not observed in the other two groups. Additionally, all patients in the HSV-1-positive group tested negative for anti-neural autoantibodies in CSF and serum samples collected approximately 3 weeks after onset. This study, therefore, highlights that CSF IgG index elevation occurs even after PCR-confirmed HSV-1 clearance, which might indicate immunopathogenesis that is independent of antibody-mediated mechanisms.

Herpes Simplex Virus Encephalitis in Patients With Autoimmune Conditions or Exposure to Immunomodulatory Medications.

BACKGROUND AND OBJECTIVES: Among infectious etiologies of encephalitis, herpes simplex virus type 1 (HSV-1) is most common, accounting for ∼15%-40% of adult encephalitis diagnoses. We aim to investigate the association between immune status and HSV encephalitis (HSVE). Using a US Medicaid database of 75.6 million persons, we evaluated the association between HSVE and autoimmune conditions, exposure to immunosuppressive and immunomodulatory medications, and other medical comorbidities. METHODS: We used the US Medicaid Analytic eXtract data between 2007 and 2010 from the 29 most populated American states. We first examined the crude incidence of HSVE in the population. We then age and sex-matched adult cases of HSVE with a sufficient enrollment period (12 months before HSVE diagnosis) to a larger control population without HSVE. In a case-control analysis, we examined the association between HSVE and exposure to both autoimmune disease and immunosuppressive/immunomodulatory medications. Analyses were conducted with conditional logistic regression progressively adjusting for sociodemographic factors, Charlson Comorbidity Index, and non-autoimmune comorbidities. RESULTS: Incidence of HSVE was ∼3.01 per 105 person-years among adults. A total of 951 HSVE cases and 95,100 age and sex-matched controls were compared. The HSVE population had higher rates of medical comorbidities than the control population. The association of HSVE and autoimmune conditions was strong (adjusted odds ratio (OR) 2.6; 95% CI 2.2-3.2). The association of HSVE and immunomodulating medications had an OR of 2.2 (CI 1.9-2.6), also after covariate adjustment. When both exposures were included in regression models, the associations remained robust: OR 2.3 (CI 1.9-2.7) for autoimmune disease and 2.0 (CI 1.7-2.3) for immunosuppressive and immunomodulatory medications. DISCUSSION: In a large, national population, HSVE is strongly associated with preexisting autoimmune disease and exposure to immunosuppressive and immunomodulatory medications. The role of antecedent immune-related dysregulation may have been underestimated to date.

Mice with type I interferon signaling deficiency are prone to epilepsy upon HSV-1 infection.

Viral encephalitis continues to be a significant public health concern. In our previous study, we discovered a lower expression of antiviral factors, such as IFN-ß, STING and IFI16, in the brain tissues of patients with Rasmussen's encephalitis (RE), a rare chronic neurological disorder often occurred in children, characterized by unihemispheric brain atrophy. Furthermore, a higher cumulative viral score of human herpes viruses (HHVs) was also found to have a significant positive correlation with the unihemispheric atrophy in RE. Type I IFNs (IFN-I) signaling is essential for innate anti-infection response by binding to IFN-α/ß receptor (IFNAR). In this study, we infected WT mice and IFNAR-deficient A6 mice with herpes simplex virus 1 (HSV-1) via periocular injection to investigate the relationship between IFN-I signaling and HHVs-induced brain lesions. While all mice exhibited typical viral encephalitis lesions in their brains, HSV-induced epilepsy was only observed in A6 mice. The gene expression matrix, functional enrichment analysis and protein-protein interaction network revealed four gene models that were positively related with HSV-induced epilepsy. Additionally, ten key genes with the highest scores were identified. Taken together, these findings indicate that intact IFN-I signaling can effectively limit HHVs induced neural symptoms and brain lesions, thereby confirming the positive correlation between IFN-I signaling repression and brain atrophy in RE and other HHVs encephalitis.

Encefalitis Autoinmune Post-Herpética / No disponible

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Role of IL-4 in an experimental model of encephalitis induced by intracranial inoculation of herpes simplex virus-1 (HSV-1) / Papel da IL-4 em modelo experimental de encefalite induzida pela inoculação intracraniana do herpes simplex vírus-1 (HSV-1)

Herpes simplex virus-1 (HSV-1) is a pathogen that may cause severe encephalitis in humans. In this study, we aimed to investigate the role of interleukin-4 (IL-4) in a model of HSV-1 brain infection. IL-4 knockout (IL-4-/-) and wild type (WT) C57BL/6 mice were inoculated with 10(4) plaque-forming units of HSV-1 by the intracranial route. Histopathologic analysis revealed a distinct profile of infiltrating cells at 3 days post-infection (dpi). Infected WT mice presented mononuclear inflammatory cells while IL-4-/- mice developed meningoencephalitis with predominance of neutrophils. IL-4-/- mice had diminished leukocyte adhesion at 3 dpi when compared to infected WT animals in intravital microscopy study. Conversely no differences were found in cerebral levels of CXCL1, CXCL9, CCL3, CCL5 and TNF-α between WT and IL-4-/- infected mice. IL-4 may play a role in the recruitment of cells into central nervous system in this acute model of severe encephalitis caused by HSV-1.

O vírus herpes simplex-1 (HSV-1) é um patógeno que pode causar encefalite grave em humanos. Neste estudo, buscamos investigar o papel da interleucina-4 (IL-4) no modelo de infecção intracerebral por HSV-1. Camundongos C57BL/6 selvagens (WT) e deficientes no gene IL-4 (IL-4-/-) foram inoculados com 10(4) unidades formadoras de placas de HSV-1 por via intracraniana. A análise histopatológica revelou um padrão distinto de infiltrado leucocitário. Camundongos WT infectados apresentaram infiltrado de células mononucleares, enquanto camundongos IL-4-/- desenvolveram meningoencefalite com predomínio de neutrófilos 3 dias pós-infecção (dpi). Animais IL-4-/- tiveram menor adesão de leucócitos 3 dpi quando comparados aos animais WT infectados à microscopia intravital. Em contrapartida, não foram encontradas diferenças nos níveis cerebrais de CXCL1, CXCL9, CCL3, CCL5 e TNF-α entre camundongos WT e IL-4-/- infectados. Esses resultados sugerem que IL-4 pode desempenhar um papel no recrutamento de células no sistema nervoso central neste modelo agudo de encefalite grave causada pelo HSV-1.