Pain Mechanism in Rheumatoid Arthritis: From Cytokines to Central Sensitization
Table 1
After injecting different cytokines into normal knee joint, the changes of the responsiveness of the nociceptive sensory neurons (Aδ and C fibers) to the mechanical stimulation of the joint. The effects of the intrathecal injection of cytokines on the responsiveness of the spinal cord induced by the joint mechanical stimulation and long-term effects of the neutralization of these cytokines on pain behavior in the animal model.
Cytokines
Responsiveness of Aδ fibers to mechanical stim.
Responsiveness of C fibers to mechanical stim.
Responsiveness of the spinal cord to mechanical stim.
Effect of neutralization on mechanical hyperalgesia (route of administration)
TNF-α
Enhance slightly
Enhance
Enhance
Reduce (intra-articular/intrathecal)
IL-1β
Reduce
Enhance
Enhance
No effect (subcutaneous)
IL-6
No effect
Enhance (difficult to reverse)
Enhance (difficult to reverse)
Reduce (pretreatment is more effective than posttreatment; intra-articular application is more effective than systemic application)
