Integrin-associated protein (IAP)-deficient mice are less susceptible to, developing Staphylococcus aureus-induced arthritis

The integrin-associated protein (IAP) has been shown to function in a signa ling complex with beta(3) integrins, influencing the migration of phagocyti c cells into inf-lamed tissues. We have previously shown that gene-targeted mice deficient for IAP succumbed to peritonitis when inoculated with Gram- negative bacteria. The aim of this study was to assess the role of IAP in o ur recently established model of haematogenously induced Staphylococcus aur eus septicaemia and arthritis. In this model, neutrophils play a crucial ro le in the early phase of the infection. Mice lacking IAP and congenic contr ols were intravenously inoculated with S. aureus LS-1. The IAP(-/-) mice we re resistant to developing clinical signs of arthritis compared with their IAP-expressing littermates. The clinical findings were corroborated by hist opathological evaluation indicating that the IAP(-/-) mice had less cartila ge and bone destruction in the joints. We believe that a delayed migration of leukocytes into the joints of mice lacking IAP expression leads to decre ased susceptibility to develop S, aureus-induced arthritis. (C) Elsevier, P aris.