Runx1 transcriptional regulation of microglia critically modulates opioid analgesia and withdrawal in humans and rodents [ChIP-seq]

Opioid pain-relief and adverse outcomes differ between individuals. We show that runt-related transcription factor 1 (Runx1) is a determinant of opioid responses in humans and rodents and modulates the microglial transcriptome. Electron microscopy and single-cell RNA-sequencing revealed that deletion of Runx1 from microglia produces distinct ultra-structural and transcriptomic signatures. Microglia Runx1-deficient mice have reduced morphine potency, despite having no prior opioid exposure and normal nociceptive thresholds. These mice required greater amounts of post-operative morphine and displayed robust morphine-induced hyperalgesia and exacerbated withdrawal. In humans, genome-wide linkage analyses (GWAS) revealed variations within the Runx1 gene is associated with inter-individual differences in perioperative opioid requirement and opioid withdrawal severity. Identification of Runx1 susceptibility genotypes has implications for individualizing opioid pain management and determining risk of opioid dependence. Overall design: Spinal cord cells were isolated from male C57BL/6J mice at 8-10 weeks of age. For each immunoprecipitation, chromatin from 10 spinal cords was pooled, yielding a sample of approximately 10 µg, and incubated with 9 µg of antibody against Runx1 (rabbit polyclonal, ab23980, lot# 1017033-4, Abcam) overnight at 4 °C with rotation. ChIP-Seq library preparation and sequencing reactions were conducted by GENEWIZ, Inc/Azenta US, Inc. (South Plainfield, NJ, USA).