Inhibition of Wnt/β-catenin signaling ameliorates osteoarthritis in a murine model of experimental osteoarthritis
Caressa Lietman, Brian Wu, Sarah Lechner, Andrew Shinar, Madhur Sehgal, Evgeny Rossomacha, Poulami Datta, Anirudh Sharma, Rajiv Gandhi, Mohit Kapoor, Pampee P. Young
Caressa Lietman, Brian Wu, Sarah Lechner, Andrew Shinar, Madhur Sehgal, Evgeny Rossomacha, Poulami Datta, Anirudh Sharma, Rajiv Gandhi, Mohit Kapoor, Pampee P. Young
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Research Article Aging Inflammation

Inhibition of Wnt/β-catenin signaling ameliorates osteoarthritis in a murine model of experimental osteoarthritis

Abstract

Osteoarthritis (OA) is a degenerative joint disease involving both cartilage and synovium. The canonical Wnt/β-catenin pathway, which is activated in OA, is emerging as an important regulator of tissue repair and fibrosis. This study seeks to examine Wnt pathway effects on synovial fibroblasts and articular chondrocytes as well as the therapeutic effects of Wnt inhibition on OA disease severity. Mice underwent destabilization of the medial meniscus surgery and were treated by intra-articular injection with XAV-939, a small-molecule inhibitor of Wnt/β-catenin signaling. Wnt/β-catenin signaling was highly activated in murine synovial fibroblasts as well as in OA-derived human synovial fibroblasts. XAV-939 ameliorated OA severity associated with reduced cartilage degeneration and synovitis in vivo. Wnt inhibition using mechanistically distinct small-molecule inhibitors, XAV-939 and C113, attenuated the proliferation and type I collagen synthesis in synovial fibroblasts in vitro but did not affect human OA-derived chondrocyte proliferation. However, Wnt modulation increased COL2A1 and PRG4 transcripts, which are downregulated in chondrocytes in OA. In conclusion, therapeutic Wnt inhibition reduced disease severity in a model of traumatic OA via promoting anticatabolic effects on chondrocytes and antifibrotic effects on synovial fibroblasts and may be a promising class of drugs for the treatment of OA.

Authors

Caressa Lietman, Brian Wu, Sarah Lechner, Andrew Shinar, Madhur Sehgal, Evgeny Rossomacha, Poulami Datta, Anirudh Sharma, Rajiv Gandhi, Mohit Kapoor, Pampee P. Young

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Figure 6

Wnt inhibitor treatment of chondrocytes does not alter proliferation but modifies gene expression.

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Wnt inhibitor treatment of chondrocytes does not alter proliferation but...
(A) Immunohistochemistry of Ki-67 in the joint from control and Wnt inhibitor mice 10 weeks after surgery demonstrated no detectable proliferation of chondrocytes after treatment with Wnt inhibitor. Original magnification, ×40. (B) Joints were stained with H&E and also by immunofluorescence with SOX9 (green), a marker for chondrocytes, and PCNA (red), a proliferating cell marker, and counterstained with DAPI (blue). Additional sections from the same joint from the XAV-939–treated sample were used as the isotype control. Images from the same joint region were used, although they are from separate sections. The H&E image is therefore reused. Isotype controls showed background but no nuclear staining. Original magnification, ×20 (first column); ×40 (rightmost 4 rows). (C) Costained PCNA-positive and SOX9-positive cells were quantified, and no significant difference was detected between control and treated groups. Statistical analysis by t test was performed, P > 0.05, n = 3. (D) Chondrocytes were isolated from patients with osteoarthritis (OA) and stained by immunofluorescence for type II collagen (green) and DAPI (blue) to confirm phenotype. Isotype controls did not show any collagen type II staining. Original magnification, ×20. (E) Proliferation was assessed by BrdU assay and showed no response in proliferation with Wnt treatment or inhibition. (F) Real-time qRT-PCR of AXIN2 demonstrates that chondrocytes are responsive to Wnt activation and inhibition by C113 and XAV-939. (G) Real-time qRT-PCR of COL2A1 demonstrates that type II collagen transcripts are downregulated in response to Wnt expression and increased after inhibition. (H) Real-time qRT-PCR of PRG4 demonstrates that Wnt inhibition in chondrocytes increases PRG4 transcript levels. (E–H) Statistical analysis was performed using a 1-way ANOVA with Tukey’s post-hoc test, *P < 0.05, **P < 0.01, ***P < 0.001, n = 5. For data presented as box-and-whiskers plots, horizontal lines indicate the medians, cross marks indicate the means, boxes indicate the 25th to 75th percentiles, and whiskers indicate the minimum and maximum values of the data set.