MedicalResearch.com Interview with:
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: A great deal of preclinical work in animal models of pain has established that activation of peripheral immune cells or, in the central nervous system (brain and spinal cord), immune cells called “glia” (microglia and astrocytes) play a key role in the establishment and/or maintenance of persistent pain. For instance, if you pharmacologically block activation of these cells in the nervous system, you are able to reduce/inhibit/prevent pain behaviors, e.g. in animals who have received a nerve injury.
This observation is very exciting, because it suggests that blocking neuroinflammation may be a viable way of treating pain. However, the evidence linking human chronic pain with neuroinflammation has so far been limited.
In this study we show, for the first time, that patients with chronic sciatica (that is, back pain that shoots down the leg) demonstrate elevations in the levels of a protein called the translocator protein (TSPO) in the spinal cord and in the nerve roots.
Because TSPO is a marker of neuroinflammation, our results suggest that sciatica is associated with neuroinflammation.
While on average patients do show elevations in the levels of the TSPO, we also saw significant variability across individuals. Importantly, patients that show stronger elevations (in the nerve roots) were those who benefit the most from receiving a local anti-inflammatory treatment (epidural spinal injection). This makes sense: patients whose nerve roots are inflamed benefit from an anti-inflammatory treatment. Those whose nerve roots aren’t inflamed, don’t receive the same benefit. In the latter case, the source of the inflammation and pain may not be the nerve roots, but may be the spinal cord, or, as we showed in a previous paper (Loggia et al., Brain 2015), the brain. Continue reading