The other side of the medal: how chemokines promote analgesia.

Chemokines are chemotactic mediators controlling cell trafficking under physiological and pathological conditions. Chemokines are not only important under various inflammatory conditions but also play a role in pain and analgesia. While many studies examined the hyperalgesic action of chemokines, recent evidence also points towards antinociceptive effects of chemokines. Such effects are indirect by recruitment of opioid containing leukocytes and stimulation of release of opioid peptides. Opioid peptides then bind to opioid receptors on peripheral sensory neurons eliciting potent analgesia. This review focuses on the analgesic role of chemokines in the periphery under inflammatory and non-inflammatory conditions.