Session Information
Date: Monday, November 13, 2023
Title: (0859–0885) Osteoarthritis & Joint Biology – Basic Science Poster
Session Type: Poster Session B
Session Time: 9:00AM-11:00AM
Background/Purpose: Osteoarthritis (OA) is the major cause of joint failure. Increasing evidence suggests that activation of fibrinolysis is involved in the pathogenesis of OA. Here we used gene expression, proteomic, in vitro assays, and mouse models to further define the role of fibrinolysis in OA.
Methods: Gene expression in synovial membranes from individuals with early- or end-stage OA and healthy individuals were analyzed, and ELISA and immunohistochemistry on human OA synovium and cartilage samples performed. Genetic and pharmacologic studies were performed targeting plasmin, tPA, uPA in an OA mouse model. We performed MicroPET/CT imaging studies on mouse OA model to further define the role of uPA in OA pathogenesis.
Results: We identified dysregulated expression of plasmin and the plasmin activators tPA, uPA and uPA receptor uPAR in human OA joints. Pharmacologic blockade of plasmin attenuated the progression of OA in DMM mice, while genetic deficiency in plasmin activator inhibitor PAI-1 or injection of plasmin protein exacerbated OA in DMM mice. We detected increased uptake of uPA/uPAR in mouse OA joints by microPET/CT imaging. Further in vitro studies identified that plasmin promotes OA development through multiple mechanisms including the degradation of lubricin and cartilage proteoglycans, activation of matrix metalloproteinases (pro-MMPs), and induction of inflammatory and degradative enzymes.
Conclusion: Our results demonstrate that fibrinolysis contributes to the development of OA through multiple mechanisms. We demonstrated that uPA and uPAR contribute to OA by activating the PI3K, PDK1, AKT, and ERK signaling cascades which mediate the production of inflammatory and degradative enzymes. Together, our results suggest that therapeutic targeting of the fibrinolysis pathways provides the potential to reduce development of OA.
(A) Unsupervised hierarchical clustering of uPA and uPAR expression in microarray dataset on synovial membranes from healthy individuals (n=7) or those with early- (n=10) or end-stage OA (n=9). Scale bar indicates z score. (B) ELISA analysis of plasmin levels in knee joint synovial fluids from individuals with OA (n=6), ACL tear (n=8), DMT (n=3) and in the plasma from healthy individuals (n=8). (C, D) ELISA analysis of activated uPA (C) or uPAR (D) levels in synovial fluid of knee joints and serum from individuals with confirmed OA (n=10). (E) Representative images from immunohistochemical staining of tPA, uPA, uPAR, and isotype control in damaged knee cartilage (left) and synovium (right) of OA from individuals underwent total knee replacement. The arrowhead indicates positive staining for tPA, uPA, and uPAR. For panels B-D, data are the mean ± SEM of duplicates or triplicates and are representative of ≥2 independent experiments. *P < 0.05, **P < 0.01, and ***P < 0.001 by t test or one-way ANOVA. For panel E, scale bar, 200μm; cartilage and synovial tissues from n = 5 individuals were analyzed and the representative images were shown.
(A) Representative cartilage degeneration in Safranin-O–stained sections of the medial region of stifle joints from plg+/+ (n=10) and plg-/- (n=5) male mice 20 weeks after DMM, and quantification of the cartilage degeneration. (B) Representative cartilage degeneration in Safranin-O–stained sections of the medial region of stifle joints from C57B/6J mice treated for 12 weeks with intra-articular injected plasmin (n=10) or PBS (n=10), and quantification of the cartilage degeneration. (C, D) Representative cartilage degeneration in Safranin-O–stained sections of the medial region of stifle joints from C57B/6J mice subjected to DMM and treated with intra-articular injection of anti-plasmin antibody (n=10), α2-macroglobulin (n=10), or PBS (n=10) (C), or with i.p. injection of tranexamic acid (n=6) or PBS (n=6) (D) for 12 weeks, and quantification of the cartilage degeneration. Arrowheads indicate areas of cartilage degeneration. Scale bars, 200μm. All data are the mean ± SEM of triplicates and are representative of three independent experiments. *P ≤ 0.05, **P ≤ 0.01 by t test or one-way ANOVA.
(A, B) Representative cartilage degeneration in Safranin-O–stained sections of the medial region of stifle joints from plau+/+ (n=10) and plau-/- (n=9) (A), and plaur+/+ (n=9) and plaur-/- (n=9) mice (B) 20 weeks after DMM, and quantification of the cartilage degeneration. Arrowheads indicate areas of cartilage degeneration. Scale bar, 200μm. (C, D) MicroPET/CT imaging of mouse knee joints 20 weeks after DMM or sham surgery, and quantification of relative 68Ga uptake levels in these joints (n=7). Mice were i.v. injected with 68Ga-NODAGA-AE105 (C), or 68Ga-NODAGA-AE105 plus unlabeled AE105 (D). (E, F) qPCR analysis of relative mRNA expression levels of OA-related inflammatory, degradative mediators as well as VEGFα in synovial tissues from plau+/+ (n=5) and plau-/- (n=5) mice (E) or plaur+/+ (n=5) and plaur-/- (n=5) mice (F) 20 weeks after DMM. Data are the mean ± SEM of duplicates or triplicates and are representative of ≥2 independent experiments. NS P > 0.05, *P ≤ 0.05, ** P ≤ 0.01, and *** P ≤ 0.001 by t test.
To cite this abstract in AMA style:
Wang Q, Wong h, Bai A, Love Z, Chu C, Robinson W. The Role of Plasmin and Fibrinolysis Pathways in Osteoarthritis [abstract]. Arthritis Rheumatol. 2023; 75 (suppl 9). https://acrabstracts.org/abstract/the-role-of-plasmin-and-fibrinolysis-pathways-in-osteoarthritis/. Accessed .« Back to ACR Convergence 2023
ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-role-of-plasmin-and-fibrinolysis-pathways-in-osteoarthritis/