Methylation alterations of WT1 and homeobox genes in inflamed muscle biopsy samples from patients with untreated juvenile dermatomyositis suggest self‐renewal capacity

Abstract

Objective To determine the impact of methylation alteration in inflamed muscles from children with Juvenile Dermatomyositis (JDM) and other Idiopathic Inflammatory Myopathies (IIM). Methods MRI-directed diagnostic muscle biopsies (MBx) from 20 JDM children and 4 healthy controls were used for genome-wide DNA methylation profiling (IRB# 200813457). Bisulfite pyrosequencing confirmed methylation status in JDM and other IIM. Immunohistochemistry defined localization and expression levels of WT1. Results Comparison of genome-wide DNA methylation profiling between JDM and normal controls revealed 27 genes with significant methylation difference, enriched with transcription factors and cell cycle regulators, unrelated to duration of untreated disease. Six homeobox genes were among them: ALX4, HOXC11, HOXD3 and HOXD4 were hypomethylated; EMX2 and HOXB1 were hypermethylated. WT1 was significantly hypomethylated in JDM (Δβ = −0.41, p < 0.001). Bisulfite pyrosequencing verification in 56 JDM samples confirmed the methylation alterations of these genes. Similar methylation alterations were observed in Juvenile Polymyositis (JPM, n = 5) and other IIM (n = 9). Concordantly, WT1 protein was increased in JDM muscle, with average positive staining of 11.6%, but was undetectable in normal muscles (p < 0.05). Conclusions These results suggest that affected muscles of children with JDM and IIM have the capacity to repair, and that homeobox and WT1 genes are epigenetically marked to facilitate this repair process, potentially suggesting new avenues of therapeutic intervention.

DNA methylation dynamics in muscle development and disease

“…Juvenile dermatomyositis (DM) is a severe chronic childhood autoimmune disease showing the affected children muscle weakness caused by chronic muscle damage (Christen-Zaech et al, 2008 ; Feldman et al, 2008 ). Comparison of genome-wide DNA methylation profiling, by Illumina Infinium Human Methylation27K BeadChip array, revealed 27 genes with significant methylation differences between normal and juvenile DM diagnosed muscle biopsies (Wang et al, 2012 ). Although previous gene expression studies showed alterations in the expression of genes involved in immune response, vascular remodeling and endoplasmic reticulum response to acid stress (Nagaraju et al, 2005 ; Chen et al, 2008 ), no significant methylation alterations in those genes were found in juvenile DM.…”

“…Although previous gene expression studies showed alterations in the expression of genes involved in immune response, vascular remodeling and endoplasmic reticulum response to acid stress (Nagaraju et al, 2005 ; Chen et al, 2008 ), no significant methylation alterations in those genes were found in juvenile DM. However, among the 27 differentially methylated genes several HOX genes (HOXC11, HOXD3 and HOXD4) and the developmental transcription factor WT1 were found hypomethylated in juvenile DM samples, as well as in other types of idiopathic inflammatory myopathies (IIMs) with muscle weakness, such as juvenile polymyositis (Wang et al, 2012 ). The similar methylation alterations of WT1 and homeobox genes found in IIMs provided additional evidences that the damaged muscles in these children had self-renewal capacity, stimulating the muscle stem cell pool towards muscle repair.…”

Update in juvenile myositis

“…In muscle biopsies from untreated JDM patients, miR-126 was significantly decreased compared with controls, and these patients had higher muscle VCAM-1 expression [ 15 ]. In their second study [ 16 ▪ ], the group investigated the epigenetic regulation of muscle gene expression by carrying out whole-genome DNA methylation profiling on muscle tissue from JDM patients prior to treatment. The authors identified 27 genes that were differentially methylated between JDM and control muscle.…”

Identification of Differently Metylated Genes Potentially Related to Human Atherosclerosis

“…В то же время, в скелетных мышцах у пациентов юве-нильным дерматомиозитом по сравнению с конт ролем выявлено снижение уровня метилирования в генах HOXD3, HOXD4 и ALX4 [23]. Такое сходство профиля метилирования гомеобокс-содержащих генов при ате-росклерозе и такого хронического системного аутоим-мунно-воспалительного заболевания скелетных мышц и васкулопатии -как ювенильный дерматомиозит, говорит об общности патогенеза данных патологиче-ских состояний, но отличается от злокачественных новообразований, которые характеризуются гиперме-тилированием данных генов.…”