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    Abstract. The environment in which the encounter of antigen with the immune system occurs determines whether tolerance, infectious immunity, or autoimmunity results. Geographical areas with low supplies of vitamin D (for example Scandinavia) correlate with regions with high incidences of multiple sclerosis, arthritis, and diabetes. The active form of vitamin D has been shown to suppress the development of autoimmunity in experimental animal models. Furthermore, vitamin D deficiency increases the severity of at least experimental autoimmune encephalomyelitis (mouse multiple sclerosis). Targets for vitamin D in the immune system have been identified, and the mechanisms of vitamin D‐mediated immunoregulation are beginning to be understood. This review discusses the possibility that vitamin D status is an environmental factor, which by shaping the immune system affects the prevalence rate for autoimmune diseases such as multiple sclerosis, arthritis, and juvenile diabetes.
    The environment in which the encounter of antigen with the immune system occurs determines whether tolerance, infectious immunity, or autoimmunity results. Geographical areas with low supplies of vitamin D (for example Scandinavia) correlate with regions with high incidences of multiple sclerosis, arthritis, and diabetes. The active form of vitamin D has been shown to suppress the development of autoimmunity in experimental animal models. Furthermore, vitamin D deficiency increases the severity of at least experimental autoimmune encephalomyelitis (mouse multiple sclerosis). Targets for vitamin D in the immune system have been identified, and the mechanisms of vitamin D-mediated immunoregulation are beginning to be understood. This review discusses the possibility that vitamin D status is an environmental factor, which by shaping the immune system affects the prevalence rate for autoimmune diseases such as multiple sclerosis, arthritis, and juvenile diabetes.
    This thesis describes several mechanisms in which T and B lymphocytes, together with the costimulatory molecules and cytokines that influence their behavior, are fundamental in the progression of autoimmunity to autoimmune disease. If these mechanisms can be understood in greater detail, more specific drug targets can be discovered, enabling better control of diseases such as type 1 diabetes, multiple sclerosis, SLE and RA while minimizing undesirable side effects resulting from the complete deletion/inactivation of non-pathogenic immune cells.
    Citations (0)
    Defining Autoimmunity and Autoimmune Disease The Discovery and Rediscovery of Autoimmunity Mechanisms of Tolerance Genetics as a Factor in Autoimmune Disease Susceptibility Environmental Factors and Autoimmune Disease The Effects of Immune Disregulation on Autoimmune Disease Development Mechanisms of Tissue Destruction and Organ Damage in Autoimmune Diseases Experimental Animal Models of Autoimmunity Autoimmunity through Immunization Treatment Strategies for Autoimmune Disease Conclusion
    This chapter contains sections titled: Introduction Proposed mechanisms for autoimmunity and autoimmune diseases Preclinical models of autoimmunity and HCT Outcomes in patients with autoimmune diseases transplanted for another primary disease HDIT and autologous HCT for autoimmune diseases: clinical experience Allogeneic HCT for autoimmune diseases: clinical experience Autoimmunity after HCT Conclusion References
    Microchimerism
    Inorganic mercury (iHg) is known to induce autoimmune disease in susceptible rodent strains. Additionally, in inbred strains of mice prone to autoimmune disease, iHg can accelerate and exacerbate disease manifestations. Despite these well-known links between iHg and autoimmunity in animal models, no association between iHg alone and autoimmune disease in humans has been documented. However, it is possible that low-level iHg exposure can interact with disease triggers to enhance disease expression or susceptibility. To address whether exposure to iHg can alter the course of subsequent acquired autoimmune disease, we used a murine model of acquired autoimmunity, lupus-like chronic graft-versus-host disease (GVHD), in which autoimmunity is induced using normal, nonautoimmune prone donor and F1 recipient mice resistant to Hg-induced autoimmunity. Our results indicate that a 2-week exposure to low-dose iHg (20 or 200 micro g/kg every other day) to donor and host mice ending 1 week before GVHD induction can significantly worsen parameters of disease severity, resulting in premature mortality. iHg pretreatment clearly worsened chronic lupus-like disease, rather than GVHD worsening iHg immunotoxicity. These results are consistent with the hypothesis that low-level, nontoxic iHg preexposure may interact with other risk factors, genetic or acquired, to promote subsequent autoimmune disease development.
    Citations (77)
    This brief review is focused on those heavy metals (cadmium, gold and mercury) that have strong associations with autoimmunity. Cadmium treatment of rats and mice results in autoimmune responses that vary with species and inbred strain of animals. However, there is no solid evidence demonstrating that the renal pathology observed in humans exposed to cadmium has an autoimmune pathogenesis. More clear-cut are the autoimmune effects of preparations containing gold salts, that have been widely used in the treatment of rheumatoid arthritis. Gold may cause autoimmune thrombocytopenia, immune complex-mediated glomerulonephritis and other autoimmune disorders. Similarly, there is solid evidence that mercury can induce autoimmune disease both in humans and experimental animals. The lessons to be derived from metal-induced autoimmunity relate to structure-activity relationship, pathogenesis, etiology and genetics. They probably apply to xenobiotic-induced autoimmune disease in general.
    Pathogenesis
    Citations (87)
    The diverse genetic backgrounds of lupus-prone murine models, which produce both quantitative and qualitative differences in disease expression, may be a valuable resource for studying the influence of environmental exposure on autoimmune disease in sensitive populations. We tested this premise by exposing autoimmune-prone BXSB and the nonautoimmune C57BL/6 mice to the heavy metal mercury. Although both strains express a nonsusceptible H-2 haplotype, exposure to mercury accelerated systemic autoimmunity in both male and female BXSB mice, whereas the C57BL/6 mice were resistant. The subclasses of antichromatin antibodies elicited in BXSB mice by mercury exposure were more consistent with the predominant Th1-type response of idiopathic disease than with the Th2-type response found in mercury-induced autoimmunity (HgIA). The appearance and magnitude of both humoral and cellular features of systemic autoimmunity correlated with the mercury dose. Furthermore, environmentally relevant tissue levels of mercury were associated with exacerbated systemic autoimmunity. These studies demonstrate that xenobiotic exposure can accelerate spontaneous systemic autoimmunity, and they support the possibility that low-level xenobiotic exposure enhances susceptibility to systemic autoimmunity in genetically susceptible individuals.
    Xenobiotic
    Citations (9)