TNF and rheumatoid arthritis: In RA patients, osteopenia appears as both periarticular and systemic, and the mechanisms are quite similar: the pro-inflammatory cytokines (TNF-α, IL-6, IL-1) and systemic inflammation, as previously mentioned, together with the RANK-L, have an inhibitory effect on osteoblastogenesis and a stimulatory effect on osteoclastogenesis, which results in lower BMD and TBS.