Conserved transcriptional programming across sex and species after peripheral nerve injury predicts treatments for neuropathic pain
Background and Purpose Chronic pain is a devastating problem affecting one in five individuals around the globe, with neuropathic pain the most debilitating and poorly treated type of chronic pain. Advances in transcriptomics have contributed to cataloguing diverse cellular pathways and transcriptomic alterations in response to peripheral nerve injury but have focused on phenomenology and classifying transcriptomic responses. Key Results We identified 93 transcripts in the dorsal horn that were increased by peripheral nerve injury in male and female mice and rats. Following gene ontology and transcription factor analyses, we constructed a pain interactome for the proteins encoded by the differentially expressed genes, discovering new, conserved signalling nodes. We investigated the interactome with the Drug-Gene database to predict FDA-approved medications that may modulate key nodes within the network. The top hit from the analysis was fostamatinib, the molecular target of which is the non-receptor spleen associated tyrosine kinase (Syk), which our analysis had identified as a key node in the interactome. We found that intrathecally administrating the active metabolite of fostamatinib, R406 and another Syk inhibitor P505-15, significantly reversed pain hypersensitivity in both sexes. Conclusions and Implications Thus, we have identified and shown the efficacy of an agent that could not have been previously predicted to have analgesic properties. Overall design: To identifying new types of pain-relieving agents, we compared transcriptional reprogramming changes in the dorsal spinal cord after spared nerve injury in male and female mice and rats, and imputed commonalities, as well as differences in cellular pathways and gene regulation.