In human rheumatoid arthritis (RA), the most severe inflammatory joint disease, autoantibodies against citrullinated proteins are among the strongest risk factors for bone destruction.  The authors found a strong association between autoantibodies against citrullinated proteins and serum markers for osteoclast-mediated bone resorption in RA patients.  In addition, human autoantibodies against mutated citrullinated vimentin bound osteoclast surfaces and produced a robust induction of osteoclastogenesis and bone-resorptive activity in vitro and in vivo. 

http://www.jci.org/articles/view/60975