The neuro-immune balance in neuropathic pain: Involvement of inflammatory immune cells, immune-like glial cells and cytokines

In a large proportion of individuals nervous system damage may lead to a debilitating chronic neuropathic pain. Such pain may now be considered a neuro-immune disorder, since recent data indicate a critical involvement of innate and adaptive immune responses following nerve injury. Activation of immune and immune-like glial cells in the injured nerve, dorsal root ganglia and spinal cord results in the release of both pro- and anti-inflammatory cytokines, as well as algesic and analgesic mediators, the balance of which determines whether pain chronicity is established. This review will critically examine the role of the immune system in modulating chronic pain in animal models of nervous system injury, and highlight the possible therapeutic opportunities to intervene in the development and maintenance of neuropathic pain.