Science News: Systemic Inflammatory Markers in Neuropathic Pain, Nerve Injury, and Recovery

Submitted by: Marcus Pai, MD, PhD
Edited by: Vishwajit Hegde, MD

Sandy-Hindmarch O, Bennett DL, Wiberg A, Furniss D, Baskozos G, Schmid AB. Systemic inflammatory markers in neuropathic pain, nerve injury, and recovery. Pain. 2022;163(3):526-537. doi:10.1097/j.pain.0000000000002386
 
Summary: This study evaluated 55 patients with carpal tunnel syndrome (CTS) and used them as a human model system of neuropathic pain / nerve injury. The study tested the hypothesis that neuroinflammation has a role in nerve injury and neuropathic pain but is an incomplete model, relying on indirect measures (e.g. systemic inflammatory markers).
 
Authors used CTS as a model because CTS is a chronic disorder, but can be successfully treated by a surgical intervention, making it possible to evaluate inflammation pre-surgery vs post-surgery.
Authors evaluated blood inflammatory mediators at both mRNA and protein levels (TGF-B, CCL5, IL-4 among others).
 
A large variation in protein levels was observed. In active stage of CTS, PTGES2 mRNA expression was lower and TGF-B/CCL5 protein levels were higher, compared to healthy controls. During recovery, 12 genes were significantly differentially expressed, including IL-9 (increased post-surgery) and IL-6 (decreased post-surgery) which had most pronounced changes.
 
Comments: Findings of this article highlight the potential role of systemic immune dysregulation and the role of cytokines in focal nerve injury and chronic neuropathic pain. The study provides important information relevant to neuropathic pain and possible biomarkers for future studies.
 
Findings of this study may help guide future validation studies and provide insights into other possible inflammatory mediators to be evaluated in future trials. Therapeutic antibodies (such as IL-6, with promising short-term effects in sciatica) could be explored. Hopefully this help in developing new non-surgical treatment options for CTS.