Epstein-Barr virus induces erosive arthritis in humanized mice.

Epstein-Barr virus (EBV) has been implicated in the pathogenesis of rheumatoid arthritis (RA) on the basis of indirect evidence, such as its presence in affected joint tissues, antigenic cross reactions between EBV and human proteins, and elevated humoral and cellular anti-EBV immune responses in patients. Here we report development of erosive arthritis closely resembling RA in humanized mice inoculated with EBV. Human immune system components were reconstituted in mice of the NOD/Shi-scid/IL-2Rγ(null) (NOG) strain by transplantation with CD34(+) hematopoietic stem cells isolated from cord blood. These humanized mice were then inoculated with EBV and examined pathologically for the signs of arthritis. Erosive arthritis accompanied by synovial membrane proliferation, pannus formation, and bone marrow edema developed in fifteen of twenty-three NOG mice transplanted with human HSC and inoculated with EBV, but not in the nine NOG mice that were transplanted with HSC but not inoculated with EBV. This is the first report of an animal model of EBV-induced arthritis and strongly suggest a causative role of the virus in RA.

[The possible curative therapy for rheumatoid arthritis--EBV infection control gene SAP and its application].

Epstein-Barr virus (EBV) belong to herpes virus group. This virus is transmitted by human contact and cause primary infection and may exist even for years in a latent state in healthy individuals. This virus may be reactivated by the dysregulation of the host immune system or possibly by virus mutation. Here we have firstly demonstrated the host defense of EBV infection and association of EBV with rheumatoid synovitis, and then discussed our own ideas of the possible treatment in near future. The key points of this new therapy are SAP (signaling lymphocytic-activation molecule associated protein) or SH2D1A (Src homology 2 domain-containing protein). SAP (or SH2D1A), an adaptor-like molecule expressed in immune cells, is composed almost exclusively of a Src homology 2 (SH2) domain. In humans, SAP is mutated and either absent or non-functional in X-linked lymphoproliferative (XLP) syndrome (Duncan disease), a disease characterized by an inappropriate response to EBV infection. SAP is essential for late B cell help and the development of long-term humoral immunity. New approach to the therapeutic method for EBV might be opened by the regulation of this molecule (SAP).