Demyelinating diseases resulting from different etiologies may share common secondary pathogenic mechanisms. The overall objective of the proposed research is to advance the understanding of the role of cytokines in the pathogenesis of demyelinating diseases. This project will focus on one demyelinating disease, globoid cell leukodystrophy, which has several advantages for experimental investigations: 1) it has an authentic genetic animal model called the twitcher mouse, 2) it has an inflammatory response that is simple by comparison to other demyelinating diseases such as multiple sclerosis and adrenoleukodystrophy, and 3) it can be treated with bone marrow transplantation (BMT). The rationale for the proposed research is based on the findings that TNFa and IL-6 expressions are elevated in twitcher mice, and twitcher/IL-6 deficient mice have a different pathological course than twitcher mice. If twitcher mice are given BMT, donor macrophages enter the brain and slow the development of pathological changes. However, donor macrophages and endogenous glial cells are still capable of producing cytokines, which may affect the therapeutic course of BMT. Based on these facts, two central hypotheses are advance: 1) IL-6 modulates the pathogenic course in twitcher mice and it promotes the therapeutic effectiveness of BMT, and 2) activated TNF receptors negatively affect twitcher mice by promoting pathogenesis, and limiting the therapeutic effectiveness of BMT. These hypotheses will be tested by the following specific aims: 1_ produce double mutant mice that carry both the twitcher and IL-6 mutations, and use them to analyze the effects of the IL-6 mutation on the clinical and pathological course in twitcher mice with and without BMT, and 2) produce double mutant mice that carry both the twitcher and TNF-receptor(R) 1 mutations or the twitcher and TNF-R2 mutations, and use them to analyze the effects of the TNF-R1 or TNF-R2 mutation on the clinical and pathological course in twitcher mice with and without BMT. The proposed studies should provide insights about the role of TNF receptors and IL-6 in the pathogenesis of globoid cell leukodystrophy, which should be relevant to other demyelinating diseases in the CNS. The long range objectives are to utilize this information to design treatment strategies that modulate cytokine expression in demyelinating diseases in general and to enhance the therapeutic effectiveness of BMT in Leukodystrophies. The project will utilize the following techniques: production of double mutant mice, immunohistochemistry, pathological and clinical evaluations, electron microscopy, PCR, ELISA and BMT.
