CD4 and systemic lupus erythematosus: Our data confirm the central role of DNMT1-mediated hypermethylation of the Foxp3-TSDR region in CD4+ T cells in disrupting Treg stability and contributing to SLE pathogenesis in MRL/lpr mice, consistent with prior research implicating DNMT1 in Treg-specific epigenetic dysregulation (53, 54).