Lumbar Disc Cytokines – Friend or Foe?

What role do anti-inflammatory (M2) and pro-inflammatory (M1) cytokines play relieving or exacerbating back pain?

Dutch researchers want to know. So, they put together a rigorous systematic review of studies which documented associations between M1 and M2 macrophages and their related effect on patient inflammation and pain.

Their work, “The contradictory effect of macrophage-related cytokine expression in lumbar disc herniations: a systematic review,” appears in the November 25, 2019 edition of the European Spine Journal.

“It is well known that macrophages can differentiate in different ways, some of these differentiations are considered pro-inflammatory (M1 type) and some anti-inflammatory (M2 type),” said co-author Niek Djuric, M.D., with the Department of Neurosurgery at the Leiden University Medical Center in The Netherlands.

“We know that macrophages play a role in pain relief in patients suffering from lumbar disc herniations by facilitating disc resorption, but some researchers also believe that they exacerbate pain symptoms through their inflammation process.”

“Since these effects are mediated by their cytokine expression profile, we wanted to know whether the anti- pro-inflammatory cytokines expressed M2 and M1 macrophages, respectively, and can that explain the relief or exacerbation of pain symptoms seen in these patients.”

“Pro-inflammatory (M1) macrophage related cytokine expression was associated with higher pain scores, whereas cytokine expression related to the anti-inflammatory (M2) macrophages was associated with lower pain scores.”

“The most important message is that cytokines expression can both positively and negatively influence pain symptoms. Cells expressing these cytokines such as macrophages should be further studied in order to maximize their beneficial effects on increasing the rate of recovery and decreasing the severity of pain symptoms in patients suffering from disc herniations.”

“Macrophage related cytokine expression plays an important role in both recovery and pain severity in lumbar disc herniations. In order to maximize their potential, further study on their differentiation in the herniated disc is needed.”