Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement
Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.
Destabilization of the Medial Meniscus As a Model to Study the Relationship Between Joint Degeneration and Pain.
Miller, Rachel E., Tran, Phuong, Ghoreishi-Haack, Nayereh, Das, Rosalina, Malfait, Anne-Marie
Background/Purpose:
Pain is the major symptom in osteoarthritis (OA), yet how this pain develops remains unknown. Our long-term goal is to quantitatively measure pain and dissect molecular pathways involved in pain generation in a mouse model of OA. We chose destabilization of the medial meniscus (DMM) in C57BL/6 mice because, unlike in other rodent OA models, the joint pathology in this model is slowly progressive over 16 weeks. Previous studies in our lab have found that mice receiving DMM surgery develop progressive mechanical allodynia in the ipsilateral hindpaw, as early as 2 weeks and progressing over 8 weeks post DMM (but not sham) surgery.
Methods:
DMM or sham surgery was performed in the right knee of 10-week old male C57BL/6 mice. At 8 and 16 weeks post surgery, histopathology of the knees was evaluated according to OARSI recommendations. Additionally, at 4 and 8 weeks after surgery, whole knee joints were collected for protein extraction and ELISA. The LABORAS system (Metris, NL) was used to measure locomotor activity at 4, 8, and 16 weeks post surgery. At the same time points, innervating dorsal root ganglia (DRG), L3-L5, from DMM or sham-operated mice and age-matched naïve mice were collected for mRNA extraction for quantitative RT-PCR of nerve growth factor (NGF), monocyte chemoattractant protein (MCP)-1 and its receptor CCR2, and stromal cell-derived factor (SDF)-1. Finally, at 8 weeks post surgery, the response of DRG neurons to chemokines was recorded though intracellular Ca2+-imaging, following standard protocols. In brief, DRG neurons were acutely isolated, plated on coverslips, cultured for 3–4 days, and loaded with a calcium indicator dye. The number of cells responding to chemokines was counted.
Results:
Following DMM (but not sham) surgery, C57BL/6 mice developed cartilage degeneration and osteophyte formation by 8 weeks in the ipsilateral knee only, with progressive cartilage deterioration occurring up to 16 weeks. At 4 weeks post DMM, protein levels of MCP-1 and NGF were elevated in total joint extracts from the operated knee compared to naïve age-matched controls; by 8 weeks post DMM, levels of both proteins had returned to baseline. Additionally, locomotor activity (measured as total distance traveled) was relatively constant over the first 8 weeks, but was decreased in DMM mice at 16 weeks post surgery compared to age-matched naïve mice.
mRNA levels of NGF, MCP-1, CCR2, and SDF-1 in the innervating DRG were upregulated compared to naïve and sham age-matched controls, peaking at 8 weeks post surgery. Exposing isolated DRG neurons from DMM mice at 8 weeks post surgery to MCP-1 or to SDF-1 (200 or 500 ng/mL, respectively) resulted in an increased calcium response compared to naïve age-matched controls, indicating an upregulation of their respective receptors, CCR2 and CXCR4, on these cells.
Conclusion:
Time-course experiments in the murine DMM model of OA enable us to quantify pain at different stages of disease. The upregulation of CCR2 and CXCR4 signaling pathways indicate that they likely play a central role in mediating painful osteoarthritis, similar to what has been reported in other neuropathic disease models; future work will address whether these pathways may serve as useful therapeutic targets.
To cite this abstract, please use the following information:
Miller, Rachel E., Tran, Phuong, Ghoreishi-Haack, Nayereh, Das, Rosalina, Malfait, Anne-Marie; Destabilization of the Medial Meniscus As a Model to Study the Relationship Between Joint Degeneration and Pain. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :1773
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