TNF and rheumatoid arthritis: For example, high circulating levels of tumour necrosis factor-alpha (TNF-α) and transforming growth factor-beta (TGF-β) have been reported in patients with RA (Arend and Gabay, 2004), but not in patients with Sjogren's syndrome (Garcic-Carrasco et al, 2001; Eriksson et al, 2004).