"Study of novel pathogenic mechanism in Huntington disease"

Abstract

Huntington Disease (HD) is a neurodegenerative disorder resulting from the expansion of polyglutamine stretch in the huntingtin protein (Htt). Mutant Htt (mHtt) leads to progressive impairment of several molecular pathways that have been linked to disease pathogenesis. Defects in the production of neurotrophic factors have been described as important determinants contributing to the development of HD. In addition to others, production of transforming growth factor-beta1 (TGF-beta1) is also deregulated in HD and shows a variable profile during disease course. TGF-beta1 levels have been reported to be markedly reduced before and at the time of HD onset in both central (human post-mortem cortex) and peripheral (serum) districts and returned to normal levels with disease severity. We have discovered that the abnormal production of peripheral TGF-beta1 depends on the changes in the percentage of TGF-beta1-producing macrophages along HD. Variation in the number of TGF-beta1-producing macrophags resulted from differential activation state of the same cells, which displayed phenotypic and functional heterogeneity throughout the clinical course of HD. Similar to the periphery, TGF-beta1 levels varied in human post-mortem brain with HD neuropathological changes. Our study highlights an interesting link between periphery and central compartment and underlines the potential of TGF-beta1 as a possible early disease marker suitable for prediction of disease onset in HD.