New Pain Process Revealed

Chronic pain caused by nerve damage is tough to treat because its underlying mechanisms aren't well-understood. But new findings by researchers at Harvard Medical School offer hope for those who suffer from this neuropathic pain. Ru-Rong Ji and colleagues report that matrix metalloprotease (MMP) enzymes involved in cellular remodeling and inflammation are also part of the pain process (Nat. Med., DOI: 10.1038/nm1723). Tests in rats and mice showed that nerve damage transiently increases production of MMP-9 in neurons and subsequently increases production of MMP-2. The team also found the MMPs wreak havoc by cleaving interleukin-1β and activating microglia and astrocytes, which have all previously been implicated in the pain process. Inhibiting MMP-9 blocks an early phase of pain associated with nerve injury, and blocking MMP-2 suppresses a late phase of pain. According to the researchers, the results suggest that inhibition of the MMP enzymes could "provide a novel therapeutic approach for the treatment of neuropathic pain."