IFN-γ inhibits EC growth as well as the expression of MMP-2 and MMP-9.[41] It can also induce expression of anti-angiogenic chemokines, such as CXCL10 and CXCL11 and down-regulate expression of pro-angiogenic CXCL12 chemokine.[1] In RA, other chemokines, such as CCL21, fractalkine and MIF mediate the synovial angiogenesis and migration of inflammatory leukocytes into the synovium.[86, 87] MIF has drawn

significant attention selleck chemical recently. This chemokine is involved in macrophage activation and cytokine production.[73] MIF is primarily produced by synovial macrophages and is involved in macrophage-derived synovial angiogenesis.[73, 88] MIF acts via the induction of VEGF and IL-8/CXCL8 release by RA synovial fibroblasts.[89] Moreover, IL-8 is an angiogenic factor. This cytokine seems to be an important factor in which synovial tissue macrophages derive chemotactic activity in ECs, so that angiogenesis could be significantly decreased if IL-8 is immunodepleted.[90] A disintegrin and metalloproteinases (ADAMs) comprise a new family of metalloproteinases, responsible for liberating a variety of cell surface expressed proteins. ADAMs has been implicated in several inflammatory reactions as RA.[91]

Several recent studies have demonstrated the effect of cytokines, such as IL-1β, Natural Product Library TNF-α and TGF-β, on the expression of ADAMs with thrombospondin motifs 4 (ADAMTS-4) and ADAMTS-5 in FLS. Mimata and colleagues suggest that IL-6 may participate in cartilage destruction in RA as an inducer of ADAMTS-4 expression from FLS.[92] Furthermore, ADAMTS-12 has been observed in the cartilage, synovial fluid and serum of arthritic patients, which may

play an important role in the pathogenesis of arthritis. Nah et al. suggest that ADAMTS12 may be a susceptible gene for RA development.[93] In particular, ADAM10 LY294002 has been shown to cleave various inflammatory and angiogenic mediators from the cell surface, including CXCL16 and CX3CL1. Soluble CXCL16 plays an important role in T cell accumulation and stimulation in RA synovium, and ADAM10 was identified as a major protease responsible for the conversion of CXCL16 from a membrane-bound scavenger receptor to a soluble chemoattractant for T cells.[94] Also, ADAM10 is involved in the constitutive cleavage of CX3CL1 and thereby may regulate the recruitment of monocytic cells to CX3CL1-expressing cell layers.[95] Recently, Isozaki et al. show that ADAM10 is overexpressed in RA and suggest that ADAM10 may play a role in RA angiogenesis.[96] Moreover, other studies have shown that ADAM15 and ADAM17 are active in RA.[97] Komiya et al. in 2005 indicated that among the ADAMs, ADAM15 mRNA was more frequently expressed in the RA patients and also it was expressed in the synovial lining cells, ECs of blood vessels and macrophage-like cells in the sublining layer of RA synovium.