Background/Purpose: Cartilage damage is often observed in affected joints with advance gout¹. Musculoskeletal ultrasound studies have highlighted the close relationship between monosodium urate (MSU) crystals and articular cartilage in patients with gout. The “double contour sign” is an hyperechoic band over the superficial layers of the articular cartilage that highlights the close relationship between MSU and cartilage². The interaction between MSU crystal and chondrocyte may contribute to cartilage damage in gout³. The objective of this study was to investigate the effect of increasing concentrations of MSU crystals on chondrocyte function and differentiation.

Methods: Primary chondrogenic cell line (ATDC5) were cultured in a 1:1 mixture of DMEM/F12 medium containing 10% FBS, Insulin-Transferrin-Selenium and incubated with increasing concentrations of endotoxin-free MSU crystals at increasing concentrations (0.01, 0.025, 0.05 and 0.1 mg/ml) for 4, 7, and 14 days respectively. Purification of total cellular RNA for real time PCR was prepared from ATDC5 at different time points. Real-time quantitative PCR was performed on specific extracellular matrix genes, transcription factors and metalloproteinases. Alcian-blue and Alizarin red S staining was performed at selected time point of ATDC5 cells exposed to different MSU concentration.

Results: MSU crystals have a negative effect in the function and differentiation of ATDC5 chondrogenic cell lines. The ability of chondrocyte to produce matrix protein assessed by relative mRNA expression of aggrecan and type II collagen was reduced in chondrocytes following culture with MSU crystals and correlated with Alcian-blue staining. The expression of of chondrogenic gene expression was found to correlate with Runx 2. The expression of Ihh, and MMP-13 was increased and confirmed by western blotting (1-way ANOVA p<0.05). Furthermore, the expression of degradative enzymes such as Adamts4 and Adamts5 was also increased contributing to the cartilage degradative process. 

Conclusion:   Long-term culture of MSU crystals with chondrogenic cell line ATDC5 impairs the function and differentiation of chondrocytes. MSU crystals stimulate gene expression of Ihh and MMP-13 contributing to the development of osteoarthritis.

References

1. McQueen FM, Chhana A, Dalbeth N. Nat Rev Rheumatol. 2012;8:173-81.

2. Filippuci E, Riveros MG, Georgescu D, Salaffi F, Grassi W. Osteoarthritis and Cartilage. 2009;17:178-81.

3. Schlesinger N, Thiele RG. Ann Rheum Dis. 2010;69:1907-12.

 Acknowledgements

This work is support from a grant from the Arthritis Foundation and COBRE grant P20GM104937 from the National Institutes of Health.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/monosodium-urate-monohydrate-crystals-induces-the-expression-of-ihh-and-mmp-13-in-atdc5-cells-implications-in-osteoarthritis-oa-development/