The investigators propose that in predisposed individuals, chronic back pain occurs due to exuberant innate immune system activation nearby the spinal nerve roots. The innate immunity activation leads to the release of pro-inflammatory cytokines [nitric oxide (NO), tumor necrosis factor-α (TNF-α), and reactive oxygen species (ROS)], and to the activation of cyclooxygenase-2 (COX-2), which produces neuroinflammation resulting in pain along the anatomical distribution of the spinal nerve roots. The investigators propose that exuberant innate immune system activation is triggered by tissue injury nearby the spinal nerve roots, (e.g., intervertebral disc pathology, or degenerative abnormalities of the spine).