Neuronal CRMP2 phosphorylation inhibition by the flavonoid, naringenin, contributes to the reversal of spinal sensitization and arthritic pain improvement

Abstract

Background Rheumatoid arthritis patients usually suffer from arthritic chronic pain. However, due to an incomplete understanding of the mechanisms underlying autoimmune disorders, the management of arthritic pain is unsatisfactory. Here, we investigated the analgesic effect and underlying mechanism of the natural flavonoid naringenin (NAR) in collagen-induced arthritis (CIA) pain. Methods NAR was injected (i.p.) once per day for 42 days after initial immunization, and rats were sacrificed on the 28th (the 21st day after final immunization, PID 21) and 42nd days (PID 35). The inflammatory factors, central sensitization indicators, and CRMP2 phosphorylation, as well as the anti-rheumatoid activity and analgesic effect of NAR, were further investigated. Results We found that NAR decreased the arthritis score and paw swelling, as well as the mechanical and thermal pain. The immunofluorescence results also showed a dose dependent effect of NAR on reducing the expressions of spinal cFos, IBA-1, and GFAP on the 28th (PID 21) and 42nd day (PID 35). NAR decreased the phosphorylation of CRMP2 S522 and the expression of the kinase CDK5 in the spinal dorsal horn, but pCRMP2 Y479 was unchanged. In addition, CRMP2 was co-localized with NEUN, but not IBA-1 or GFAP, indicating the involvement of neural CRMP2 phosphorylation in CIA-related pain. Finally, CRMP2 S522 phosphorylation selective inhibitor (S)-lacosamide also alleviated arthritic pain. Conclusions Taken together, our results demonstrate that NAR alleviates inflammation and chronic pain in CIA model, which might be related to its inhibition of neuronal CRMP2 S522 phosphorylation, potentially mitigating the central sensitization. Our study provide evidence for the potential use of NAR as non-opioid-dependent analgesia in arthritic pain.

Peptide and Peptidomimetic Inhibitors Targeting the Interaction of Collapsin Response Mediator Protein 2 with the N-Type Calcium Channel for Pain Relief

“…13,135 Blockage of this PTM is the mechanism by which the small molecule (S)-lacosamide ((S)-LCM) and the natural product naringenin alleviate pain. 143,144 Notably, neither CBD3 peptide nor CBD3063 treatment altered the phosphorylation state of CRMP2 at the Thr509/ Thr514, Ser522, or Thr555 sites. 25,96 Because CRMP2 phosphorylation is enhanced in pain states, we can infer from our in vivo preclinical studies that CBD3063's effectiveness was not prevented by phosphorylation.…”

“…Phosphorylation of CRMP2 has important implications for both its function in pain and in neurodegenerative disease. The interaction of CRMP2 with Ca V 2.2 and Na V 1.7 channels is enhanced by phosphorylation of CRMP2 by Cdk5 at Ser522. ,,− Hyperphosphorylation of CRMP2 is observed in chronic pain. , Blockage of this PTM is the mechanism by which the small molecule (S)-lacosamide ((S)-LCM) and the natural product naringenin alleviate pain. , Notably, neither CBD3 peptide nor CBD3063 treatment altered the phosphorylation state of CRMP2 at the Thr509/Thr514, Ser522, or Thr555 sites. , Because CRMP2 phosphorylation is enhanced in pain states, we can infer from our in vivo preclinical studies that CBD3063’s effectiveness was not prevented by phosphorylation. Further, hyperphosphorylated CRMP2 is found inand may contribute to pathogenesis ofa number of other neurodegenerative conditions, as we recently reviewed. , For these reasons, it will be illuminating to examine the potential for cross-talk between CBD3063 and CRMP2 phosphorylation.…”