TNF and rheumatoid arthritis: The important role of methylation in monocyte pathophysiology is highlighted by a recent study, which demonstrated a difference in DNA methylation profiling between monocytes isolated from RA patients and healthy subjects: the study revealed how RA monocytes are characterized by hypermethylated CpG sites related to several genes, including IFN and TNF, suggesting a potential implication of these cytokines and their signaling pathways in the acquisition of a further aberrant DNA methylation signature in RA patients (28).