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Published on: March 12, 2020
Estrogen receptor-related receptor-alpha (ERR-alpha) is dysregulated in inflammatory arthritis
E Bonnelye1, N Laurin, P Jurdic
1Department of Molecular Genetics, Faculty of Medicine, University of Toronto, Room 6233, Medical Sciences Building, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.
Objectives:
Subchondral bone loss is a characteristic feature of inflammatory arthritis. Recently, estrogen receptor-related receptor-alpha (ERR-alpha), an orphan nuclear receptor, has been found to be involved in activation of macrophages. We hypothesized that ERR-alpha which is expressed and also functional in articular chondrocytes, osteoblasts and osteoclasts, may be involved in rodent models of inflammatory arthritis.
Methods:
Erosive arthritis was induced in DBA/1 mice by injection of type II collagen in Freund's complete adjuvant. RNA was isolated from the bone and joints and expression of ERR-alpha and cartilage (GDF5 and Col2a1) and bone [bone sialoprotein (BSP) and osteocalcin (OCN)] markers was analysed by semi-quantitative PCR.
Results:
We report for the first time that the expression of ERR-alpha is dysregulated in bones and joints in a mouse model of inflammatory arthritis. Specifically, we show that ERR-alpha expression is down-regulated early in bone and later in joints of mice with type II CIA. Concomitantly, temporal changes were observed in GDF-5 and Col2a1 expression in joints following both initial injection and booster injection of type II collagen. Similarly, down-regulation of ERR-alpha mRNA expression in subchondral bone in mice with induced joint inflammation was also paralleled by down-regulation of markers of bone formation (BSP, OCN).
Conclusions:
These data suggest that dysregulation of ERR-alpha expression may precede and contribute to the destruction of cartilage and bone accompanying inflammatory arthritis.
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