Human class I major histocompatibility complex alleles determine central nervous system injury versus repair

Abstract

Background: We investigated the role of human HLA class I molecules in persistent central nervous system (CNS) injury versus repair following virus infection of the CNS. Methods: Human class I A11+ and B27+ transgenic human beta-2 microglobulin positive (Hβ2m+) mice of the H-2b background were generated on a combined class I-deficient (mouse beta-2 microglobulin deficient, β2m0) and class II-deficient (mouse Aβ0) phenotype. Intracranial infection with Theiler's murine encephalomyelitis virus (TMEV) in susceptible SJL mice results in acute encephalitis with prominent injury in the hippocampus, striatum, and cortex. Results: Following infection with TMEV, a picornavirus, the Aβ0.β2m0 mice lacking active immune responses died within 18 to 21 days post-infection. These mice showed severe encephalomyelitis due to rapid replication of the viral genome. In contrast, transgenic Hβ2m mice with insertion of a single human class I MHC gene in the absence of human or mouse class II survived the acute infection. Both A11+ and B27+ mice significantly controlled virus RNA expression by 45 days and did not develop late-onset spinal cord demyelination. By 45 days post-infection (DPI), B27+ transgenic mice showed almost complete repair of the virus-induced brain injury, but A11+ mice conversely showed persistent severe hippocampal and cortical injury. Conclusions: The findings support the hypothesis that the expression of a single human class I MHC molecule, independent of persistent virus infection, influences the extent of sub frequent chronic neuronal injury or repair in the absence of a class II MHC immune response.