Epstein-Barr virus genomic DNA and Epstein-Barr nuclear antigen 3A (EBNA-3A) as triggers of pro-inflammatory mechanisms -

Abstract

Epstein-Barr virus (EBV), a member of the Herpesviridea family, is a DNA virus that establishes latent infections that often later reactivate. Potential associations between EBV and several autoimmune diseases such as rheumatoid arthritis (RA) have been reported. Previous studies have also demonstrated a role for EBV nuclear antigens, such as EBNA-3A, in B lymphocyte transformation; moreover, cytotoxic T-lymphocytes specific to EBNA-3 protein family members are the most prevalent CD8+T cells during a latent EBV infection. On the other hand, studies conducted at our department have shown that EBV DNA may enhance the production of the pro-inflammatory cytokine Interleukin 17 (IL-17), which has been shown to contribute to a large number of autoimmune diseases. Therefore, we intended to study the effect of EBNA-3A and EBV DNA on autoimmune pathways. We examined whether these viral components are capable of triggering IL-17 production in female BALB-c mice and in human peripheral blood mononuclear cells (PBMCs) from patients with RA in culture. Different mouse groups, each containing 9 female BALB-c mice, were intraperitoneally injected with an increasing amount of EBNA-3A with or without EBV DNA. One group was injected only with sterile water (the DNA and EBNA-3A solvent) and another was left uninjected. After 3, 6, and 9 days of injection, IL-17 and IL-10, as a pro-inflammatory and an anti-inflammatory cytokine, respectively, were measured in mice sera using an enzyme-linked immunosorbent assay (ELISA). On the other hand, PBMCs from 7 EBV positive RA patients and 7 non-RA control subjects were cultured in the presence or absence of EBNA-3A and-or EBV DNA for 24 hrs. Culture supernatants were then collected and examined for IL-17 and IL-10 levels by ELISA. Mouse groups injected with EBV DNA showed increased levels of IL-17 starting from day 6 post-injection. Similarly, when received alone, 5 and 10 μg of EBNA-3A increased IL-17 levels in mice after 9 days of injection. These levels were also increased in all m