DNMT3A and systemic lupus erythematosus: DNA methylation and DNMT3a levels were reduced, and H3K4me3 enrichment was elevated within CREMα promoter of SLE CD4+ T cells, and SUV39H1 binding positively correlated with the levels of DNA methylation and DNMT3a and negatively correlated with the H3K4me3 enrichment at this region