Background and objective Systemic sclerosis (SSc) is an autoimmune connective tissue disease with a high all cause mortality. Although there is a small genetic component it is likely that the majority of variation in the disease is due to epigenetic events. Methylation is important in regulating gene expression and methylated DNA can bind to MeCP2 aiding repression. MeCP2 is more commonly associated with the neurological disease Rett syndrome where this is enriched, but MeCP2 is expressed ubiquitously. It is known that MeCP2/Rett mice are protected from experimentally induced liver fibrosis. The aim of this study was to examine the role of MeCP2 in systemic sclerosis.
Materials and methods Dermal fibroblasts were isolated from patients or controls from skin punch biopsies n = 5. MeCP2 was quantitated by real time PCR and normalised to 18S housekeeping gene. MeCP2 was silenced with MeCP2 siRNA or scramble control siRNA using HiPerfect transfection. Collagen was measured using qPCR and alpha smooth muscle actin was quantitated using western blotting method. PPAR-γ was also measured. Mice were treated with bleomycin to induce fibrosis. Skin sections from the mice treated or control was measured for MeCP2 and collagen levels by qPCR.
Results SSc dermal fibroblasts have significantly elevated MeCP2 levels compared to controls. Silencing of MeCP2 levels attenuates the expression of collagen transcripts and alpha-Sma expression. Also reduction of MeCP2 leads to elevated PPAR-γ. Mice treated with bleomycin have elevated levels of MeCP2 and collagen levels within the fibrotic skin.
Conclusion MeCP2 is important in SSc and is elevated. MeCP2 appears to regulate ECM markers. PPAR-γ is a master regulator of fibrosis and this may be altered by MeCP2 levels leading to derepression of ECM genes.