Here, we show that in arthritis pain, dorsal horn microglia acquire a unique transcriptional profile that is driven by TLR4 upregulation and is enriched in pathways regulating the production and effect of IL-1β, TNF-α and IFN-β, which have been reported to regulate nociception in the K/BxN ST model13,32. The gene discussed is TLR4; the disease is arthritic joint disease.