PRTN3 and rheumatoid arthritis: Antigen- and collagen-induced arthritis (ACIA) is a new mouse model that displays key features of RA such as chronic joint inflammation, cartilage and bone erosion, and prominent autoimmune responses against autologous collagen II, and anti-citrullinated peptide/protein antibodies (ACPA) that can be observed in the majority of RA patients [9].