Epigenetic clues to rheumatoid arthritis.

The innate immune response needs to be tightly regulated to balance elimination of microorganisms with the magnitude of inflammation. The rupture of this balance is crucial for the outcome of diseases such as rheumatoid arthritis (RA) in which an overflowed proinflammatory response is associated with self-damage. Epigenetics alludes to systems controlling gene expression and silencing independent of the germline, but stable enough to be inherited by daughter cells upon mitosis. We will show in this review how pathological processes in RA can be shaped by epigenetics, which may in turn explain differences in phenotypes between subgroups of patients and also between subsets of fibroblasts within the joint. On the whole, the concourse of epigenetic mechanisms can precipitate the aggressive behaviour of cells and the rupture of peripheral tolerance. Targeting these emerging regulatory pathways is a promising approach for RA therapeutics.