Inclusion body myositis (IBM) is the leading age-related skeletal muscle disorder, yet its etiology remains unknown, nor do effective treatments exist. We developed novel transgenic models that mimic IBM-like motor deficits and pathology, including Aft accumulation and tau phosphorylation in skeletal muscle. This proposal investigates the genetic and pharmacologic factors that modulate the severity of IBM-like pathology in transgenic mice. Our preliminary data indicate that the accumulation of Aft plays a pivotal role in its pathogenesis. Consequently, factors that augment Aft, such as inflammation, exacerbate the phenotype, whereas we propose that interventions that reduce Afi may be an effective therapeutic strategy to delay or cure IBM. The first two aims are continuation of current studies. Aim 1 determines the pathologic effect of inflammatory responses in skeletal muscle on Aft and tau and also evaluate any anti-inflammatory agents modulate these IBM-like pathology. In aim 2,1 will utilize our transgenic IBM models to determine if Aft immunotherapy ameliorates the motor deficits and myopathology. We will investigate the effect of active immunization as a potential treatment for IBM; the outcome of this study may justify the initiation of a human clinical trial with IBM patients. The last aim (aim 3) focuses on the molecular link between myopathy and dementia, based on the current finding of genetic link between these diseases. I will generate novel transgenic mice harboring a clinical mutation in the valosin-containing protein (VCP) gene, responsible for IBM/Paget disease/frontotemporal dementia. Mutations on VCP may be involved in the abnormal accumulation of disease-relevant proteins found in both IBM and some neurodegenerative disorders. Thus, the mouse models will be useful both for therapeutic evaluation and for investigating any shared molecular mechanisms underlying the pathogenesis of these distinct diseases. This latter point is worth emphasizing as many dementia-related proteins accumulate in damaged muscle fibers in IBM, suggesting that there may be a coordinated cellular response to these proteins; thus, information learned from these models may be applicable to dementias like Alzheimer disease. Furthermore, providing multiple lines of disease models may accelerate the research progress in the field. Through this application, we hope to advance the understanding of IBM as well as dementias and evaluate potential therapeutic strategies for IBM. [unreadable] [unreadable] [unreadable] [unreadable]