CD13, an ectoenzyme on myeloid and stromal cells, also circulates as a shed, soluble protein (sCD13) with powerful chemoattractant, angiogenic, and arthritogenic properties, which require engagement of a G protein–coupled receptor (GPCR). Here we identify the GPCR that mediates sCD13 arthritogenic actions as the bradykinin receptor B1 (B1R). Immunofluorescence and immunoblotting verified high expression of B1R in rheumatoid arthritis (RA) synovial tissue and fibroblast-like synoviocytes (FLSs), and demonstrated binding of sCD13 to B1R. Chemotaxis, and phosphorylation of Erk1/2, induced by sCD13, were inhibited by B1R antagonists. In ex vivo RA synovial tissue organ cultures, a B1R antagonist reduced secretion of inflammatory cytokines. Several mouse arthritis models, including serum transfer, antigen-induced, and local innate immune stimulation arthritis models, were attenuated in Cd13–/– and B1R–/– mice and were alleviated by B1R antagonism. These results establish a CD13/B1R axis in the pathogenesis of inflammatory arthritis and identify B1R as a compelling therapeutic target in RA and potentially other inflammatory diseases.
Pei-Suen Tsou, Chenyang Lu, Mikel Gurrea-Rubio, Sei Muraoka, Phillip L. Campbell, Qi Wu, Ellen N. Model, Matthew E. Lind, Sirapa Vichaikul, Megan N. Mattichak, William D. Brodie, Jonatan L. Hervoso, Sarah Ory, Camila I. Amarista, Rida Pervez, Lucas Junginger, Mustafa Ali, Gal Hodish, Morgan M. O’Mara, Jeffrey H. Ruth, Aaron M. Robida, Andrew J. Alt, Chengxin Zhang, Andrew G. Urquhart, Jeffrey N. Lawton, Kevin C. Chung, Tristan Maerz, Thomas L. Saunders, Vincent E. Groppi, David A. Fox, M. Asif Amin
This file is in Adobe Acrobat (PDF) format. If you have not installed and configured the Adobe Acrobat Reader on your system.
PDFs are designed to be printed out and read, but if you prefer to read them online, you may find it easier if you increase the view size to 125%.
Many versions of the free Acrobat Reader do not allow Save. You must instead save the PDF from the JCI Online page you downloaded it from. PC users: Right-click on the Download link and choose the option that says something like "Save Link As...". Mac users should hold the mouse button down on the link to get these same options.