Osteopontin Level in Synovial Fluid Is Associated with the Severity of Joint Pain and Cartilage Degradation after Anterior Cruciate Ligament Rupture

Abstract

ObjectiveTo explore the molecular function of Osteopontin (OPN) in the pathogenesis of human OA, we compared the expression levels of OPN in synovial fluid with clinical parameters such as arthroscopic observation of cartilage damage and joint pain after joint injury.MethodsSynovial fluid was obtained from patients who underwent anterior cruciate ligament (ACL) reconstruction surgery from 2009 through 2011 in our university hospital. The amounts of intact OPN (OPN Full) and it’s N-terminal fragment (OPN N-half) in synovial fluid from each patient were quantified by ELISA and compared with clinical parameters such as severity of articular cartilage damage (TMDU cartilage score) and severity of joint pain (Visual Analogue Scale and Lysholm score).ResultsWithin a month after ACL rupture, both OPN Full and N-half levels in patient synovial fluid were positively correlated with the severity of joint pain. In contrast, patients with ACL injuries greater than one month ago felt less pain if they had higher amounts of OPN N-half in synovial fluid. OPN Full levels were positively correlated with articular cartilage damage in lateral tibial plateau.ConclusionOur data suggest that OPN Full and N-half have distinct functions in articular cartilage homeostasis and in human joint pain.

Osteoarthritis-related biomarkers following anterior cruciate ligament injury and reconstruction: a systematic review

“…All studies assessing ACL-D patients utilized a caseecontrol study design. Among studies with ACL-R patients, five studies 26,28,29,32,33 utilized a longitudinal design, two studies 27,31 utilized a caseecontrol design, and one study 30 utilized both a longitudinal and caseecontrol design. The mean CASP score was 5.9 out of a possible 11 points for caseecontrol studies (mode ¼ 6, range ¼ 4e9) and seven out of a possible 12 points for longitudinal studies (mode ¼ 7, range ¼ 5e8).…”

Role of osteopontin in osteosarcoma

“…OPN is also known as bone sialoprotein I (BSP-1 or BNSP), early T lymphocyte activation (ETA-1) and secreted phosphoprotein 1 (SPP1), expressed in the mineralized extracellular matrix (ECM) of bone and in other tissues and cells including fibroblasts, osteoblasts, osteocytes, hypertrophic chondrocytes, dendritic cells, macrophages, smooth muscle cells and activated T cells [9][10][11]. OPN contains the RGD (Arg-Gly-Asp) sequence that interacts with cells through many different integrin, including a4b1, a9b1, a9b4, av (b1, b3, b5) and CD44, and activates a number of regulatory and structural proteins, such as focal adhesion kinase, Src and cytoskeletal proteins which in turn could activate a number of different signal transduction pathways [12][13][14] involved in many biological processes such as biomineralization, bone remodeling, immune responses and pathological processes such as inflammatory disease, atherosclerosis, ischemia, autoimmune diseases, cancer and stress-dependent angiogenesis [12,15].…”

Osteopontin Bridging Innate and Adaptive Immunity in Autoimmune Diseases

“…In line with a role of the cryptic domain, high levels of thrombin, OPN-N, and OPN-C have been detected in the synovial fluid of patients with RA. The levels of OPN-C and OPN-N correlate with the disease's severity, and the thrombin inhibitor hirudin ameliorates collagen-induced arthritis [149]. Moreover, the activity of OPN-N may be inhibited by thrombin-activatable carboxypeptidase B (CPB), which cleaves the C-terminal arginine from the cryptic site [150].…”