TNF and rheumatoid arthritis: Genetically modified mouse models with deregulated expression of TNF develop an erosive polyarthritis resembling RA (huTNFtg) (Keffer et al., 1991) and SpAs (spondyloarthropathies) (TNFΔARE [Kontoyiannis et al., 1999], TgA86 [Küsters et al., 1997; Vafeiadou et al., 2020]), showing also extra-articular manifestations, such as heart valve disease and intestinal inflammation, recapitulating comorbid pathologies often observed in humans (Kontoyiannis et al., 1999; Ntari et al., 2018).