Immuno-histo-chemical Localization and Proof of Expression of sigma-1 Receptor in Tissues Resected from Surgery of Patients with Low Back Pain

Introduction: The current diagnostic tools that we have for back pain have low sensitivity and poor accuracy which leads to ineffective and unnecessary treatments, resulting in high health care costs and unwanted outcomesSigma–1 Receptors (S1R) have been strongly implicated in nociceptive signaling and peripheral pain sensation and present the opportunity to localize low back pain (LBP). The aim of this study was to prove the expression of S1R, using immuno-histo-chemistry, in local tissues resected from patients with low back pain.

Methods: Patients who were determined to have discogenic LBP based on clinical presentation and imaging, were prospectively enrolled. Per clinical standard of care, anterior lumbar interbody fusion (ALIF) was performed, and the excised disc samples were processed on to slides. Immunostaining was carried out with polyclonal antibody to the human S1R (Abcam, Boston, MA), after which the slides were examined by a histopathologist for positivity.

Results: We successfully collected 20 intervertebral disc tissue samples from 11 patients. Pathological review of the slides was completed with all samples, except one, showing positive staining with S1R. S1R staining was positive in both cartilaginous and collagenous disc material, confirming the discs as the cause of pain. All patients reported a significant improvement or complete resolution of their back pain at the 3-month post-operative time interval.

Conclusion : While previous work has established that S1R is induced in the central nervous system (CNS) in response to peripheral pain, here we provide evidence that S1R is expressed in tissues at the source of pain as well. S1R present a novel opportunity to localize the source of LBP and differentiate between multiple structural abnormalities to guide therapy.