Relation between FCGRIIB rs1050501 and HSV-1 specific IgG antibodies in Alzheimer's disease

A genome-wide association study identifies novel loci of vertigo in an Asian population-based cohort

The contributing genetic factors of vertigo remain poorly characterized, particularly in individuals of non-European ancestries. Here we show the genetic landscape of vertigo in an Asian population-based cohort. In a two-stage genome-wide association study (Ncase = 6199; Ncontrol = 54,587), we identify vertigo-associated genomic loci in DROSHA and ZNF91/LINC01224, with the latter replicating the findings in European ancestries. Gene-based association testing corroborates these findings. Interestingly, both genes are enriched in cerebellum, a key structure receiving sensory input from the vestibular system. Subjects carrying risk alleles from lead SNPs of DROSHA and ZNF91 incur a 1.74-fold risk of vertigo than those without. Moreover, composite clinical-polygenic risk scores allow differentiation between patients and controls, yielding an area under receiver operating characteristic curve of 0.69. This study identified novel genomic loci for vertigo in an Asian population-based cohort, which may help identifying high risk subjects and provide mechanistic insight in understanding the pathogenesis of vertigo.

Herpes Simplex Viral Infection Doubles the Risk of Dementia in a Contemporary Cohort of Older Adults: A Prospective Study

Background

Evidence indicates that herpes simplex virus (HSV) participates in the pathogenesis of Alzheimer's disease (AD).

Objective

We investigated AD and dementia risks according to the presence of herpesvirus antibodies in relation to anti-herpesvirus treatment and potential APOE ɛ4 carriership interaction.

Methods

This study was conducted with 1002 dementia-free 70-year-olds living in Sweden in 2001-2005 who were followed for 15 years. Serum samples were analyzed to detect anti-HSV and anti-HSV-1 immunoglobulin (Ig) G, anti-cytomegalovirus (CMV) IgG, anti-HSV IgM, and anti-HSV and anti-CMV IgG levels. Diagnoses and drug prescriptions were collected from medical records. Cox proportional-hazards regression models were applied.

Results

Cumulative AD and all-cause dementia incidences were 4% and 7%, respectively. Eighty-two percent of participants were anti-HSV IgG carriers, of whom 6% received anti-herpesvirus treatment. Anti-HSV IgG was associated with a more than doubled dementia risk (fully adjusted hazard ratio = 2.26, p = 0.031). No significant association was found with AD, but the hazard ratio was of the same magnitude as for dementia. Anti-HSV IgM and anti-CMV IgG prevalence, anti-herpesvirus treatment, and anti-HSV and -CMV IgG levels were not associated with AD or dementia, nor were interactions between anti-HSV IgG and APOE ɛ4 or anti-CMV IgG. Similar results were obtained for HSV-1.

Conclusions

HSV (but not CMV) infection may be indicative of doubled dementia risk. The low AD incidence in this cohort may have impaired the statistical power to detect associations with AD.

Inhibitory Fcγ Receptor and Paired Immunoglobulin Type 2 Receptor Alpha Genotypes in Alzheimer's Disease

We investigated whether FCGRIIB (rs1050501 C/T) and PILRA (rs1859788 A/G) genotypes contributed to the development of Alzheimer's disease (AD). We genotyped 209 African American (AA) and 638 European American (EA) participants for the FCGRIIB and PILRA alleles. In the AA cohort, subjects homozygous for the C allele of FCGRIIB were more than 4 times as likely to develop AD as those homozygous for the alternative T allele. This SNP also interacted with PILRA: participants who were the carriers of the FCGRIIB C allele and PILRA A allele were 3 times as likely to develop AD as those who lacked these alleles.

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.