Mice microglia cytokine profile changes under the influence of HSV-1

Abstract

Introduction. Today, prevalence of neurodegenerative diseases increases. In recent years, more studies have revealed a new knowledge about the role of microglia in the development of these diseases. Animal experiments showed that peripheral inflammation causes activation of microglia in brain. All this points to the essential role of the cells in the development of neurodegeneration. Under the influence of various factors, microglia can change the phenotype and participate in both repair and damage to brain cells. Chronic herpesvirus infection caused by HSV-1 is another known factor in the development of neurodegenerative pathology. However, the exact pathogenetic mechanisms are still unknown, nevertheless, studying the virus effect on microglia has great potential. The goal of our study in this connection was to assess the effect of HSV-1 on microglia polarization in mouse strain with normal susceptibility to this virus and in strain which is more resistant to the action of HSV-1. For this purpose, changes in the cytokine profile were detected. A comparison of interstrain differences in the expression of cytokine genes was also compared in control groups. Materials and methods. The study involved infecting C57BL/6 and BALB/c mice with herpes simplex virus type 1, an isolation of microglia was based on separation steps using a discontinuous gradient density, the cytokine profile was assessed by gene expression levels using a real-time reverse transcription PCR. To calculate the relative fold gene expression of samples the 2–ΔΔCt method was used. Statistical significance was determined using the Mann–Whitney U-test. Results. There were found no interstrain differences in cytokine gene expression in control groups of different mouse strains. At the same time, gene expression differed in the experimental groups: in BALB/c mice, the expression of genes for both pro-inflammatory and anti-inflammatory cytokines increased; in C57BL/6 mice, a slight increase in the expression of IL-1β genes was observed. Conclusion. The data indicate the formation of different microglial phenotypes after HSV-1 infection in different mouse strains. Apparently, in BALB/c mice there is a switch from the pro-inflammatory M1 phenotype of microglia to the anti-inflammatory M2 phenotype, while in C57BL/6 mice the attenuation of the infectious process occurs through a return to the original M0 phenotype.

Keywords

• il-10
• il-1β
• il-6
• tnfα
• tgf-β
• cytokines
• gene expression
• hsv-1
• microglia
• neurodegeneration