OP0224 Adamts-12 protects against inflammatory arthritis through interacting with proinflammatory ctgf
Authors: W. Fu, J. Wei, A. Hettinghouse, W. He, C. Liu
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> It has been reported that a disintegrin and metalloproteinase with thrombospondin motifs-12 (ADAMTS-12) is a susceptibility gene for rheumatoid arthritis (RA) development, and its level was significantly increased in RA patients. In addition, ADAMTS-12 was also reported to be required for normal inflammation. <h3>Objectives</h3> This study aims to determine the role of ADAMTS-12 and the underlying mechanisms in the pathogenesis of inflammatory arthritis. <h3>Methods</h3> Collagen-induced arthritis (CIA) was established in ADAMTS-12-/- mice and their control littermates to determine the role of ADAMTS-12 <i>in vivo</i>. Connective tissue growth factor (CTGF) deficient Raw264.7 were used to determine their functional interplays. Protein-protein interaction assays were performed to detect the interactions of ADAMTS-12 with CTGF <h3>Results</h3> <b>ADAMTS-12-/- mice are more susceptible to collagen-induced arthritis.</b> Accelerated disease onset, significant increase in the arthritis score and arthritis incidence, were observed in ADAMTS-12-/- mice (figure 1a). Histological analysis of whole ankle joints demonstrated a significant increase in synovitis, destruction of bone and cartilage loss in ADAMTS-12-/- mice. ELISA results indicated that ADAMTS-12-/- CIA mice exhibited enhanced release of pro-inflammatory and reduced secretion of anti-inflammatory cytokine. Collectively, these data demonstrate that ADAMTS-12-/- renders mice highly susceptible to CIA. <b>ADAMTS-12 interacts with and cleaves CTGF, and ADAMTS-12-mediated signalling depends on CTGF during inflammation.</b> It is known that CTGF plays a pro-inflammatory role in the pathogenesis of inflammatory arthritis. We co-transfected CTGF and ADAMTS-12 into 293 T cells and found ADAMTS-12 bound to (figure 1b) and digested CTGF (figure 1c). <i>In vivo</i> studies also demonstrated that CTGF was accumulated in the synovium of ADAMTS-12-/- CIA mice. To further determine whether CTGF is a critical regulator of ADAMTS-12 mediated signalling, we generated CTGF deficient Raw264.7. Overexpression of ADAMTS-12 and CTGF deficiency could decrease the activation of inflammatory signalling markers such as NFkb, p38 and JNK in response to IL-1β at a comparable level. More importantly, overexpression of ADAMTS-12 in CTGF deficient Raw264.7 failed to further inhibit the activation of these signal molecules as compared to CTGF deficient Raw264.7 (figure 1f). Taken together, these results suggest that CTGF is a critical regulator of ADAMTS-12 mediated signalling during inflammation. <b>Blocking CTGF attenuates inflammatory arthritis in ADAMTS12-deficient CIA mice model.</b> To determine whether the accelerated inflammation in ADAMTS-12-/- mice resulted from the accumulated CTGF, we administered CTGF antibody to ADAMTS-12-/- CIA model after disease onset. The arthritis score in ADAMTS-12 deficient mice was significantly reduced in presence of CTGF antibody (figure 1d). Moreover, histological analysis indicated CTGF abrogated further tissue destruction and inflammation (figure 1e). <h3>Conclusions</h3> ADAMTS-12-mediated regulation of inflammatory arthritis is probably through, at least in part, its interplay with CTGF and blockage of CTGF has been shown to be effective in treating inflammatory arthritis. <h3>Disclosure of Interest</h3> None declared