Cytokine profile in degenerated painful intervertebral disc: variability with respect to duration of symptoms and type of disease

Abstract

Background context: Neuroinflammation is supposed to play a crucial role in the generation of chronic pain. Numerous trials have documented the contribution of proinflammatory cytokines in the pathophysiology of pain associated with peripheral and central nociception. Local and systemic expressions of proinflammatory cytokines have been implicated as mediators of pain. Among these cytokines, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) are especially notable because of their hyperalgesic impacts after nerve damage.

Purpose: The aim of the present study was to evaluate and compare the tissue levels of IL-1β, IL-6, interleukin-10 (IL-10), and TNF-α in subligamentous and free fragment types of degenerated intervertebral disc in acute and chronic periods.

Study design: This was a cross-sectional study.

Patient sample: A cross-sectional study was implemented on a total of 49 patients (24 women, 25 men) with an average age of 38.2±4.9 treated surgically by means of microdiscectomy.

Outcome measures: Of these cases, 19 had complaints for less than 6 months, whereas 30 patients had been suffering from low back pain and leg pain for more than 6 months. Thirty-eight patients have been diagnosed with subligamentous type and 11 patients had free fragment type of disc degeneration.

Methods: The levels of IL-1β, IL-6, IL-10, and TNF-α were assessed in tissue samples prepared from nucleus pulposus tissue obtained during microdiscectomy. Results were compared in patients with acute and chronic duration of complaints, as well as subligamentous and free fragment types of intervertebral disc degeneration.

Results: The levels of IL-1β (p<.001), IL-6 (p<.001), IL-10 (p<.001), and TNF-α (p<.001) were significantly higher in patients with acute duration of complaints. Similarly, free fragment type of intervertebral disc degeneration displayed remarkably higher levels of IL-1β (p=.009), IL-6 (p<.001), IL-10 (p=.024), and TNF-α (p=.017) compared with the subligamentous type.

Conclusions: Inflammatory cytokines seem to have a more apparent role in intervertebral disc degeneration especially in acute period and in free fragment type. Further trials should be performed for elucidation of pathophysiology at the molecular level and the development of more effective diagnostic and therapeutic measures.

Keywords: Cytokines; Duration of symptoms; IL-10; IL-1β; IL-6; Intervertebral disc, degeneration; Low back pain; Nucleus pulposus; TNF-α.