[Herpesvirus infections and immunological disturbances in patients with different stages of Alzheimer's disease]

Abstract

Introduction: Alzheimer's disease (AD) is a multifactorial disease that leads to a progressive memory loss, visualspatial impairments, emotional and personality changes. As its earliest pre-dementia clinical stage, amnestic mild cognitive impairment syndrome (aMCI) is currently considered. Neuroinflammation plays a role in the development and progression of aMCI and the initial stage of AD, which can be supported by immunological disorders of a systemic character. Study of factors, including infections, influencing immune disorders and systemic inflammatory response in patients with aMCI, is of great importance.The aim of this study was to obtain new data on the possible role of herpesvirus infections in the development and progression of aMCI.

Material and methods: 100 patients with aMCI diagnosis, 45 patients with AD, 40 people from the control group were enrolled into the study. The frequency of DNA detection of herpesviruses (Epstein-Barr virus (EBV), human herpesviruses (HHV) type 6 and 7, cytomegalovirus (CMV)), the levels of viral load and the serological markers of herpesvirus infections (IgG to HHV-1, IgG to CMV) were determined. Immunological studies included an assessment of the level of the main pro-inflammatory and anti-inflammatory cytokines, and indicators of humoral and cellular immunity.

Results: The study found an increased detection rate of EBV in saliva and a higher level of EBV DNA in saliva in aMCI and AD than in the control group. A relationship between the presence of active EBV infection and changes in immunological parameters in patients with aMCI were found. It was also discovered that the level of IgG antibodies to CMV is associated with the stage of AD.

Discussion: The results indicate a possible role of EBV- and CMV-induced infections in the development of immunological changes which are typical for mild cognitive impairment and in the progression of AD.

Conclusion: The obtained data can be important for prognostic methods addressing AD development, including its pre-dementia stage, and for new approaches to individualized treatment and prevention.