Publication Date
2018
Journal Title
Blood
Abstract
© 2018 by The American Society of Hematology. Hemophilic arthropathy (HA) is a debilitating degenerative joint disease that is a major manifestation of the bleeding disorder hemophilia A. HA typically begins with hemophilic synovitis that resembles inflammatory arthritides, such as rheumatoid arthritis, and frequently results in bone loss in patients. A major cause of rheumatoid arthritis is inappropriate release of the proinflammatory cytokine tumor necrosis factor-a (TNF-a) by the TNF-a convertase (TACE; also referred to as ADAM17) and its regulator, iRhom2. Therefore, we hypothesized that iRhom2/ADAM17-dependent shedding of TNF-a also has a pivotal role in mediating HA. Here, we show that addition of blood or its components to macrophages activates iRhom2/ADAM17-dependent TNF-a shedding, providing the premise to study the activation of this pathway by blood in the joint in vivo. For this, we turned to hemophilic FVIII-deficient mice (F82/2mice), which develop a hemarthrosis following needle puncture injury with synovial inflammation and significant osteopenia adjacent to the affected joint. We found that needle puncture–induced bleeding leads to increased TNF-a levels in the affected joint of F82/2 mice. Moreover, inactivation of TNF-a or iRhom2 in F82/2 mice reduced the osteopenia and synovial inflammation that develops in this mouse model for HA. Taken together, our results suggest that blood entering the joint activates the iRhom2/ ADAM17/TNF-a pathway, thereby contributing to osteopenia and synovitis in mice. Therefore, this proinflammatory signaling pathway could emerge as an attractive new target to prevent osteoporosis and joint damage in HA patients.
Volume Number
132
Issue Number
10
Pages
1064 - 1074
Document Type
Article
Status
Faculty
Facility
School of Medicine
Primary Department
General Pediatrics
PMID
DOI
10.1182/blood-2017-12-820571