S100A8 and rheumatoid arthritis: S100A8/A9 expression can be induced in monocytes, endothelial cells, keratinocytes or epithelial cells by mediators such as LPS and TNF56, 57 and it is often increased in acute and chronic inflammatory conditions56, including rheumatoid arthritis, cancers and neurological disorders58, 59 where they seem to play cytokine-like pro-inflammatory effects55.