Zoecklein, Laurie

AbstractTheiler's murine encephalomyelitis virus causes a chronic demyelinating disease in susceptible strains of mice that is similar to human multiple sclerosis. Several nonmajor histocompatibility complex–linked genes have been implicated as determinants of susceptibility or resistance to either demyelination or virus persistence. In this study, we used linkage analysis of major histocompatibility complex identical H-2d (DBA/2J × B10.D2) F2 intercross mice to identify loci associated with susceptibility to virus-induced demyelinating disease. In a 20-cM region on chromosome 14, we identified four markers, D14Mit54, D14Mit60, D14Mit61, and D14Mit90 that are significantly associated with demyelination. Because two peaks were identified, one near D14Mit54 and one near D14Mit90, it is possible that two loci in this region are involved in controlling demyelination.

Amyotrophic lateral sclerosis (ALS) is a devastating, fatal neurologic disease that primarily affects spinal cord anterior horn cells and their axons for which there is no treatment. Here we report the use of a recombinant natural human IgM that binds to the surface of neurons and supports neurite extension, rHIgM12, as a therapeutic strategy in murine models of human ALS. A single 200 µg intraperitoneal dose of rHIgM12 increases survival in two independent genetic-based mutant SOD1 mouse strains (SOD1G86R and SOD1G93A) by 8 and 10 days, delays the onset of neurologic deficits by 16 days, delays the onset of weight loss by 5 days, and preserves spinal cord axons and anterior horn neurons. Immuno-overlay of thin layer chromatography and surface plasmon resonance show that rHIgM12 binds with high affinity to complex gangliosides GD1a and GT1b. Addition of rHIgM12 to neurons in culture increases α-tubulin tyrosination levels, suggesting an alteration of microtubule dynamics. We previously reported that a single peripheral dose of rHIgM12 preserved neurologic function in a murine model of demyelination with axon loss. Because rHIgM12 improves three different models of neurologic disease, we propose the IgM may act late in the cascade of neuronal stress and/or death by a broad mechanism.

AbstractCNSregeneration is a desirable goal for diseases of brain and spinal cord. Current therapeutic strategies for the treatment of multiple sclerosis (MS) aim to eliminate detrimental effects of the immune system, so far without reversing disability or affecting long‐term prognosis in patients. Approachable molecular targets that stimulateCNSrepair are not part of the clinical praxis or have not been identified yet. The purpose of this study was to identify the molecular target of the human monoclonal antibodyHIgM12.HIgM12 reverses motor deficits in chronically demyelinated mice, a model ofMS. Here, we identified polysialic acid (PSA) attached to the neural cell adhesion molecule (NCAM) as the antigen forHIgM12 by using differentNCAMknockout strains and throughPSAremoval from theNCAMprotein core. Antibody binding toCNStissue and primary cells, antibody‐mediated cell adhesion, and neurite outgrowth onHIgM12‐coated nitrocellulose was detected only in the presence ofPSAas assessed by western blotting, immunoprecipitation, immunocytochemistry, and histochemistry. We conclude thatHIgM12 mediates it'sin vivoandin vitroeffects through binding toPSAand has the potential to be an effective therapy forMSand neurodegenerative diseases.imageThe human antibody HIgM12 stimulates neurite outgrowthin vitroand promotes function in chronically demyelinated mice, a model of multiple sclerosis. The cellular antigen for HIgM12 was undetermined. Here, we identified polysialic acid attached to NCAM (neural cell adhesion molecule) as the cellular target for HIgM12. This includes glial fibrillary acidic protein (GFAP)‐positive mouse astrocytes (GFAP, red; HIgM12, green; DAPI, blue) among other cell types of the central nervous system. These findings indicate a new strategy for the treatment of neuro‐motor disorders including multiple sclerosis.

ABSTRACTThe RNA-dependent RNA polymerase 3Dpolis required for the elongation of positive- and negative-stranded picornavirus RNA. During the course of investigating the effect of the transgenic expression of viral genes on the host immune response, we evaluated the viral load present in the host after infection. To our surprise, we found that 3D transgenic expression in genetically susceptible FVB mice led to substantially lower viral loads after infection with Theiler's murine encephalomyelitis virus (TMEV). As a result, spinal cord damage caused by chronic viral infection in the central nervous system was reduced in FVB mice that expressed 3D. This led to the preservation of large-diameter axons and motor function in these mice. The 3D transgene also lowered early viral loads when expressed in FVB-Dbmice resistant to persistent TMEV infection. The protective effect of 3D transgenic expression was not altered in FVB-Rag−/−.3D mice that are deficient in T and B cells, thus ruling out a mechanism by which the overexpression of 3D enhanced the adaptive immune clearance of the virus. Understanding how endogenously overexpressed 3D polymerase inhibits viral replication may lead to new strategies for targeting therapies to all picornaviruses.

ABSTRACTWe evaluated the participatory role of human HLA-DR molecules in control of virus from the central nervous system and in the development of subsequent spinal cord demyelination. The experiments utilized intracranial infection with Theiler's murine encephalomyelitis virus (TMEV), a picornavirus that, in some strains of mice, results in primary demyelination. We studied DR2 and DR3 transgenic mice that were bred onto a combined class I-deficient mouse (beta-2 microglobulin deficient; β2m0) and class II-deficient mouse (Aβ0) of theH-2bbackground. Aβ0.β2m0mice infected with TMEV died within 18 days of infection. These mice showed severe encephalomyelitis due to rapid replication of virus genome. In contrast, transgenic mice with insertion of a single human class II major histocompatibility complex (MHC) gene (DR2 or DR3) survived the acute infection. DR2 and DR3 mice controlled virus infection by 45 days and did not develop spinal cord demyelination. Levels of virus RNA were reduced in HLA-DR transgenic mice compared to Aβ0.β2m0mice. Virus-neutralizing antibody responses did not explain why DR mice survived the infection and controlled virus replication. However, DR mice showed an increase in gamma interferon and interleukin-2 transcripts in the brain, which were associated with protection. The findings support the hypothesis that the expression of a single human class II MHC molecule can, by itself, influence the control of an intracerebral pathogen in a host without a competent class I MHC immune response. The mechanism of protection appears to be the result of cytokines released by CD4+T cells.

ABSTRACT Epidemiological studies suggest that an environmental factor (possibly a virus) acquired early in life may trigger multiple sclerosis (MS). The virus may remain dormant in the central nervous system but then becomes activated in adulthood. All existing models of MS are characterized by inflammation or demyelination that follows days after virus infection or antigen inoculation. While investigating the role of CD4 + T cell responses following Theiler's virus infection in mice deficient in STAT4 or STAT6, we discovered a model in which virus infection was followed by demyelination after a very prolonged incubation period. STAT4−/− mice were resistant to demyelination for 180 days after infection, but developed severe demyelination after this time point. Inflammatory cells and up‐regulation of Class I and Class II MHC antigens characterized these lesions. Virus antigen was partially controlled during the early chronic phase of the infection even though viral RNA levels remained high throughout infection. Demyelination correlated with the appearance of virus antigen expression. Bone marrow reconstitution experiments indicated that the mechanism of the late onset demyelination was the result of the STAT4−/− immune system. Thus, virus infection of STAT4−/− mice results in a model that may allow for dissection of the immune events predisposing to late‐onset demyelination in MS.

ABSTRACTWe evaluated the role of gamma interferon (IFN-γ) in protecting neurons from virus-induced injury following central nervous system infection. IFN-γ−/−and IFN-γ+/+mice of the resistant major histocompatibility complex (MHC)H-2bhaplotype and intracerebrally infected with Theiler's murine encephalomyelitis virus (TMEV) cleared virus infection from anterior horn cell neurons. IFN-γ+/+H-2bmice also cleared virus from the spinal cord white matter, whereas IFN-γ−/−H-2bmice developed viral persistence in glial cells of the white matter and exhibited associated spinal cord demyelination. In contrast, infection of IFN-γ−/−mice of the susceptibleH-2qhaplotype resulted in frequent deaths and severe neurologic deficits within 16 days of infection compared to the results obtained for controls. Morphologic analysis demonstrated severe injury to spinal cord neurons in IFN-γ−/−H-2qmice during early infection. More virus RNA was detected in the brain and spinal cord of IFN-γ−/−H-2qmice than in those of control mice at 14 and 21 days after TMEV infection. Virus antigen was localized predominantly to anterior horn cells in infected IFN-γ−/−H-2qmice. IFN-γ deletion did not affect the humoral response directed against the virus. However, the level of expression of CD4, CD8, class I MHC, or class II MHC in the central nervous system of IFN-γ−/−H-2qmice was lower than those in IFN-γ+/+H-2qmice. Finally, in vitro analysis of virus-induced death in NSC34 cells and spinal motor neurons showed that IFN-γ exerted a neuroprotective effect in the absence of other aspects of the immune response. These data support the hypothesis that IFN-γ plays a critical role in protecting spinal cord neurons from persistent infection and death.