CD4 and systemic sclerosis: They showed that hypermethylation of the regulatory region of the forkhead box protein 3 (FOXP3) gene -transcription factor crucial for CD4+ regulatory T (Treg) cell development -was linked to reduced mRNA expression and circulating Treg cells in SSc and demonstrated that in vitro treatment of CD4+ T cells with a methylation inhibitor restored Foxp3 gene expression and Treg development.