Background/Purpose:

Surgical destabilization of the medial meniscus (DMM) in the mouse knee results in slowly progressive osteoarthritis (OA), characterized by moderate joint damage by week 8 and severe joint damage by week 16 after surgery. Progressive joint damage is associated with pain-related behaviors, including knee hyperalgesia and mechanical allodynia in the ipsilateral hindpaw (Miller RE et al. PNAS, 2012).

Knee hyperalgesia occurs in the early stages of experimental OA, week 2-8 after DMM surgery (Miller RE et al. Arthr Rheum 2017). We have previously shown that C-C Chemokine Receptor 2 (CCR2) signaling plays a key role in persistence of mechanical allodynia in this model, but has no effect on joint damage (Miller RE et al. PNAS, 2012). Here, we aimed to assess the effect of CCR2 blockade on knee hyperalgesia in the early phase of the disease.

Methods:

DMM or sham surgery was performed on the right knee of 10-week old male C57BL/6 wild type (WT) or Ccr2 null mice. Two, 4, and 8 weeks after surgery (n= 4-12/time point), knee hyperalgesia was measured by Pressure Application Measurement (PAM), as described (Miller RE et al. Arthr Rheum, 2017).

To study the effect of systemic pharmacological blockade of CCR2, CCR2 antagonist (5mg/kg) (CCR2RA, RS504393, Tocris) or vehicle control (100% DMSO₄) was injected intraperitoneally (i.p.), 4 or 8 weeks after surgery in WT mice. Knee hyperalgesia was assessed hourly for 3 hours after injection.

To study the effect of local CCR2 blockade in the knee, 5µL of CCR2RA (0.4mg/kg) (BMS CCR2 22, RD Systems) (n=4) or 5µL of vehicle control (50% EtOH) (n=3) were injected intra-articularly (IA) 7 weeks after DMM surgery in WT mice. Knee hyperalgesia was measured hourly for 4 hours.

In addition, MCP-1 (5µL of 100ng/µL), the ligand for CCR2, or vehicle control (5µL PBS in 0.1% BSA) were injected IA in the right knee of 10-week old naïve WT and Ccr2 null mice (n=4/group), and knee hyperalgesia was assessed up to 24 hours after injection.

Results:

WT mice developed knee hyperalgesia 2 weeks after DMM but not sham surgery, and this was maintained until week 8. In contrast, Ccr2 null DMM mice were protected from hyperalgesia up to week 8 (p<0.0001 at week 2, 4, and 8).

Systemically administered CCR2RA alleviated established hyperalgesia in WT mice, 4 and 8 weeks after DMM (p<0.0001 compared to vehicle). Likewise, IA injection of CCR2RA into the knee joint 7 weeks after DMM reversed hyperalgesia (p<0.05 compared to vehicle).

IA administration of MCP-1, but not vehicle, rapidly induced knee hyperalgesia in naïve WT mice (p<0.001 compared to vehicle control), but not in Ccr2 null mice.

Conclusion:

These findings suggest a role for MCP1-CCR2 signaling in the development of knee hyperalgesia after DMM surgery. Furthermore, the findings with IA injection of MCP-1 or CCR2RA suggest that the effect is mediated by CCR2 present in the intra-articular space and that CCR2 is important for early OA knee pain.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/effect-of-local-and-systemic-ccr2-blockade-on-knee-hyperalgesia-in-a-mouse-model-of-osteoarthritis/