Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Monosodium Urate Monohydrate Crystals Inhibit Osteoblast Viability and Differentiation; Implications for Development of Bone Erosion in Chronic Gout.

Chhana2,  Ashika, Callon2,  Karen, Pool2,  Bregina, Naot2,  Dorit, McQueen2,  Fiona M., Cornish2,  Jillian, Dalbeth1,  Nicola

Univ Auckland, Auckland, New Zealand
University of Auckland, Auckland, New Zealand

Background:

Bone erosion is a frequent manifestation of chronic gout, and may lead to joint damage and disability. Recent research has implicated an imbalance of bone remodeling in the development of bone erosion in gout, with enhanced formation of bone-resorbing osteoclasts in patients with erosive gout. We hypothesized that changes in the bone-forming osteoblasts also contribute to bone erosion in chronic gout. In this study we investigated the effects of monosodium urate monohydrate (MSU) crystals on osteoblasts.

Method:

MSU crystals were prepared by recrystallisation of uric acid. Flow cytometry and the MTT assay were used to assess cell viability following culture with MSU crystals in the murine MC3T3-E1 and ST2 osteoblast-like cell lines, and in primary rat and human osteoblasts. Quantitative real-time PCR and von Kossa stained mineralised bone nodule formation assays were used to assess the effects of MSU crystals on the differentiation of MCT3-E1 osteoblast-like cells.

Results:

MSU crystals rapidly reduced viability in all osteoblast assays in a dose-dependent manner (Figure). The inhibitory effect was maximal at the higher concentrations of 0.3 and 0.5mg/mL MSU crystals and was independent of crystal phagocytosis. The reduction of osteoblast viability was specific to urate crystals, as soluble uric acid did not alter cell viability. Furthermore, the effects on cell viability did not alter with different crystal lengths or addition of serum. Long term culture of MC3T3-E1 cells with MSU crystals showed decreased mineralisation (bone nodule formation) in a dose-dependent manner, and reduced expression of genes related to osteoblast differentiation such as Ibsp (bone sialoprotein), Runx2, Sp7 (osterix) and Dmp1.

Conclusion:

MSU crystals have profound inhibitory effects on osteoblast viability and differentiation. These data indicate that MSU crystals may contribute to bone erosion in gout not only through promotion of osteoclast formation, but also through reduction of osteoblast survival and function.

Figure 1. Effects of MSU crystals on cell viability in A. MC3T3-E1 cells; B. ST2 cells; C. primary rat osteoblasts; and D. primary human osteoblasts. Cell viability was assessed in the MTT assay following 26 hours of culture with MSU crystals. Data shown are mean (SEM); *p<0.001, **p<0.0001 versus control (no MSU crystals), one-way ANOVA with post hoc Dunnett's test.

To cite this abstract, please use the following information:
Chhana, Ashika, Callon, Karen, Pool, Bregina, Naot, Dorit, McQueen, Fiona M., Cornish, Jillian, et al; Monosodium Urate Monohydrate Crystals Inhibit Osteoblast Viability and Differentiation; Implications for Development of Bone Erosion in Chronic Gout. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :881
DOI: 10.1002/art.28649

Abstract Supplement

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