TRPV4 and TRPM8 as putative targets for chronic low back pain alleviation

The purpose of this study is to investigate the presence of nervous fibers and expression of TRP channels in samples harvested during decompressive/fusion spine surgeries from patients affected by chronic low back pain (CLBP). The aim was to understand if members of this family of receptors played a role in detection and processing of painful stimuli, to eventually define them as potential targets for CLBP alleviation. Expression of transient receptor potential (TRP) channels (A1, V1, V2, V4, and M8) was evaluated in samples from different periarticular sites of 6 patients affected by CLBP, at both protein and transcript levels. The capsular connective pathological tissue appeared infiltrated by sensitive unmyelinated nervous fibers. An increase in TRP channel mRNAs and proteins was observed in the pathological capsule compared with tissues collected from the non-symptomatic area in five of the six analyzed patients, independently by the location and number of affected sites. In particular, TRPV4 and TRPM8 were consistently upregulated in pathological tissues. Interestingly, the only patient showing a different pattern of expression also had a different clinical history. TRPV4 and TRPM8 channels may play a role in CLBP and warrant further investigations as possible therapeutic targets. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00424-020-02460-8) contains supplementary material, which is available to authorized users.