GSE194174
Time dependent gene expression post SNL in IPSA vs Contralateral DRGs
Chronic pain can be debilitating, and current treatments are neither universally efficacious, nor without risks. New therapeutic options are needed. Transient receptor potential (TRP) ion channels regulate inflammation and pain. Understanding how endogenous TRP ligands regulate inflammation and pain may provide insights for new therapies. Spinal nerve ligation (SNL) injury was used as a model for chronic pain. Transcriptomic and targeted lipidomic analysis of damaged tissue revealed time-dependent increases in Cyp1b1 mRNA and a concurrent accumulation of 8,9-EET and 19,20-EpDPA post injury. Production of 8,9-EET and 19,20-EpDPA by human CYP1B1 and mouse Cyp1b1 was confirmed in vitro. 8,9-EET and 19,20-EpDPA selectively and dose-dependently sensitized and activated TRPA1 in overexpressing HEK-293 cells and Trpa1-expressing/AITC-responsive cultured mouse peptigergic DRG neurons. Activation of TRPA1 was attenuated by the antagonist A967079, and mouse Trpa1 was more responsive to agonists including 8,9-EET and 19,20-EpDPA than human TRPA1. This latter effect was mediated in part by amino acids Y933, G939, and S921. Intra-plantar injection of 19,20-EpDPA induced acute mechanical, but not thermal hypersensitivity in mice, which was blocked by A967079. Similarly, Cyp1b1 knockout mice displayed a reduced chronic pain phenotype, indicating a role for Cyp1b1-derived oxylipins in promoting Trpa1 activation and pain. Manipulation of the CYP1B1-oxylipin-TRPA1 axis following nerve injury could have therapeutic benefit. Overall design: Mice were used as their own controls to compare injured vs uninjured DRG gene expression