Epigenetics and Systemic Lupus Erythematosus: Unmet Needs

Systemic lupus erythematosus (SLE) is a chronic relapsing–remitting autoimmune disease affecting several organs. Although the management of lupus patients has improved in the last years, several aspects still remain challenging. More sensitive and specific biomarkers for an early diagnosis as well as for monitoring disease activity and tissue damage are needed. Genome-wide association and gene mapping studies have supported the genetic background for SLE susceptibility. However, the relatively modest risk association and the studies in twins have suggested a role for environmental and epigenetic factors, as well as genetic–epigenetic interaction. Accordingly, there is evidence that differences in DNA methylation, histone modifications, and miRNA profiling can be found in lupus patients versus normal subjects. Moreover, impaired DNA methylation on the inactive X-chromosome was suggested to explain, at least in part, the female prevalence of the disease. Epigenetic markers may be help in fulfilling the unmet needs for SLE by offering new diagnostic tools, new biomarkers for monitoring disease activity, or to better characterize patients with a silent clinical disease but with an active serology. Anti-DNA, anti-phospholipid, and anti-Ro/SSA autoantibodies are thought to be pathogenic for glomerulonephritis, recurrent thrombosis and miscarriages, and neonatal lupus, respectively. However, tissue damage occurs occasionally or, in some patients, only in spite of the persistent presence of the antibodies. Preliminary studies suggest that epigenetic mechanisms may explain why the damage takes place in some patients only or at a given time.