IFNβ Treatment Inhibits Nerve Injury-induced Mechanical Allodynia and MAPK Signaling By Activating ISG15 in Mouse Spinal Cord.

Neuropathic pain is difficult to treat and remains a major clinical challenge worldwide. While the mechanisms which underlie the development of neuropathic pain are incompletely understood, interferon signaling by the immune system is known to play a role. Here, we demonstrate a role for interferon β (IFNβ) in attenuating mechanical allodynia induced by the spared nerve injury in mice. The results show that intrathecal administration of IFNβ (dosages up to 5,000 U) produces significant, transient, and dose-dependent attenuation of mechanical allodynia without observable effects on motor activity or feeding behavior, as is common with IFN administration. This analgesic effect is mediated by the ubiquitin-like protein interferon-stimulated gene 15 (ISG15), which is potently induced within the spinal cord following intrathecal delivery of IFNβ. Both free and conjugated ISG15 are elevated following IFNβ treatment, and this effect is increased in UBP43-/- mice lacking a key deconjugating enzyme. The IFNβ-mediated analgesia reduces MAPK signaling activation following nerve injury, and this effect requires induction of ISG15. These findings highlight a new role for IFNβ, ISG15, and MAPK signaling in immunomodulation of neuropathic pain and may lead to new therapeutic possibilities. PERSPECTIVE: Neuropathic pain is frequently intractable in a clinical setting, and new treatment options are needed. Characterizing the antinociceptive potential of IFNβ and the associated downstream signaling pathways in preclinical models may lead to the development of new therapeutic options for debilitating neuropathies.