IFNG and rheumatoid arthritis: The role of IFN-γ in osteoclastogenesis is controversial; indeed, in studies conducted in vitro [51] and in vivo, in animal model, it shows an antiosteoclastogenic effect [52], whereas, in humans, IFN-γ increases in presence of bone loss due to oestrogen deficiency and rheumatoid arthritis [53, 54].