CXCL12 and Arthritis: This is consistent with models of collagen-induced arthritis in which CXCL12 acts as a pro-inflammatory factor in the pathogenesis of inflammatory arthritis [49, 50], and with human studies in which CXCL12 enhances cellular proliferation and cytokine expression by peripheral blood T cells, upregulates expression of cytokines and chemokines by fibroblast-like synoviocytes from patients with RA [51], and mediates lymphocyte ingress into RA synovial tissue, synovial neovascularisation, and osteoclastogenesis [52].