Finally, mtDNA has been shown to increase neutrophil Receptor Activator of NF-κB Ligand (RANKL) expression in synovial fluid, possibly contributing to the typical erosive joint damage in RA, as RANKL is the key cytokine that activates osteoclasts, which in turn lead to bone destruction [20, 50]. Here, TNFSF11 is linked to rheumatoid arthritis.