DNMT1 and systemic lupus erythematosus: At the miRNA level, upregulation of miR-148a and miR-21 in the MRL/LPR mouse model results in reduced DNA methyltransferase 1 (DNMT1) expression and decreased DNA methylation levels, exacerbating lupus (104).In SLE patients, the expression level of mRNA methyltransferase NSUN2 in CD4+T cells is decreased, and the Methylation level of mRNA m5 C Methylation in CD4+T cells is abnormally increased.