Recombinase-activating gene 1-associated expression of the myelin basic protein 1-11-specific transgenic T-cell receptor in H-2b mice.

We pursued a breeding strategy intended to generate disease-resistant mice with exclusive expression of the H-2(u)-restricted myelin basic protein (MBP) 1-11 peptide-specific transgenic (Tg) T-cell receptor (TCR) on the T-cell-deficient RAG1KO (H-2(b)) background. Utilizing specific screening assays for the offspring, analyses of the F1 intercross and subsequent crosses revealed that the TgTCR-associated clonotypic marker detected by the 3H12 mAb could be found only in association with the H-2(b) homozygous background in offspring possessing a functional rag1 gene. Moreover, expression of the MBP-specific TgTCR could not be found in H-2(b) homozygous offspring that were RAG1 deficient (rag1(-/-)). PCR analysis of genomic DNA from these 3H12-negative offspring verified the presence of the TCR transgenes. Thus, the presence of a functional rag1 gene was required for the expression of the MBP-specific TgTCR on the H-2(b) background. Given the role for RAG1, the results have important implications for T-cell repertoire development.

Bone marrow lacking integrin expression facilitates an enhanced susceptibility to EAE in the xenogeneic bone marrow chimeras.

Xenotransplantation of rat bone marrow cells (BMC) into immunodeficient (SCID) mice generates chimeric mice susceptible to paralytic autoimmune CNS inflammation. Herein, we identified a disease relevant subset of transplantable BMC lacking expression of CD11b/c and CD49d. Moreover, disease susceptibility was enhanced in the presence of non-myelin specific T-cells. Only the CD11b/c negative population of BM retained the capability to populate the blood, spleen and spinal cord of recipients and matured after transplant to express CD11b/c. These results indicate non-myelin T cells in combination with integrin negative BM represent pre-pathogenic determinants of an enhanced disease susceptibility to myelin reactive T cells.

A telemetric study of physiologic changes in mice with induced autoimmune encephalomyelitis.

Dysfunction of the autonomic nervous system may be an important component of disease progression in multiple sclerosis (MS), a paralytic inflammatory autoimmune disease of the central nervous system. Using the experimental autoimmune encephalomyelitis mouse model of MS, the authors carried out a pilot study to investigate whether telemetric monitoring might be a feasible approach for detecting disturbances in the autonomic control of heart rate and blood pressure after disease induction. Telemetric monitoring devices that were implanted in mice provided useful information regarding the physiologic changes that accompanied disease induction and progression. Changes were observed in heart rate, blood pressure, heart rate variability and diurnal rhythm immediately before and after disease onset. The device implantation procedure did not seem to alter the course of disease. Further investigation may establish these methods as a system for studying the relationships between MS progression and autonomic regulation of physiological status.

Treatment of experimental autoimmune encephalomyelitis with alpha lipoic acid and associative conditioning.

We have initiated studies to evaluate the suitability of performing therapeutic conditioning trials in experimental autoimmune encephalomyelitis (EAE) mice treated with alpha lipoic acid (ALA). EAE was induced in SJL mice by active immunization with myelin antigen. Once daily subcutaneous injection of ALA served as the unconditional stimulus (US) administered with the conditional stimulus (CS) saccharin-flavored drinking water under a regimen of restricted water access. In the first study, we found that water restriction and saccharin administration were compatible with disease development and effective ALA treatment of EAE mice. In the second study, mice were conditioned to once daily administration of ALA paired with administration of saccharin-flavored water (US+CS) on days 7-16. Test trials spanned experimental days 17-32 in groups receiving either saccharin-flavored water (CS, in the experimental group) versus unflavored water (CSo, in the control group) and compared several measures of EAE severity using multivariate ANOVA (MANOVA). Reduced disease severity in the experimental group (US+CS:CS) compared to the control group (US+CS:CSo) suggested that conditioning had occurred. These results demonstrate an approach for conducting therapeutic conditioning trials in EAE mice and suggest considerations for future investigations.

Epitope spreading is not required for relapses in experimental autoimmune encephalomyelitis.

The sequential emergence of specific T lymphocyte-mediated immune reactivity directed against multiple distinct myelin epitopes (epitope spreading) has been associated with clinical relapses in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Based on this association, an appealing and plausible model for immune-mediated progression of the advancing clinical course in MS and EAE has been proposed in which epitope spreading is the cause of clinical relapses in T cell-mediated CNS inflammatory diseases. However, the observed association between epitope spreading and disease progression is not universal, and absolute requirements for epitope spreading in progressive EAE have not been tested in the absence of multiple T cell specificities, because most prior studies have been conducted in immunocompetent mouse strains that possessed broad TCR repertoires. Consequently, the precise nature of a causal relationship between epitope spreading and disease progression remains uncertain. To determine whether relapsing or progressive EAE can occur in the absence of epitope spreading, we evaluated the course of disease in mice which possessed only a single myelin-specific TCR. These mice (transgenic/SCID +/+) exhibited a progressive and sometimes remitting/relapsing disease course in the absence of immune reactivity to multiple, spreading myelin epitopes. The results provide direct experimental evidence relevant to discussions on the mechanisms of disease progression in MS and EAE.