Quercetin targets the Ccl4–Ccr5 axis to relieve neuropathic pain after spinal cord injury

Spinal cord injury (SCI) severely disrupts the central nervous system, with neuropathic pain (NP) emerging as a prevalent and challenging complication, affecting approximately two-thirds of affected individuals. This study aims to explore the immune landscape and potential drug therapeutic targets associated with NP post-SCI using single-cell and bulk RNA sequencing. We identified 1050 differentially expressed genes enriched in cytokine interactions and inflammatory pathways, including key pain-related genes like Itgb2, Ccr5, Fcrg3, and Adora3, through weighted gene co-expression network analysis and immune infiltration analysis. Cell communication analysis revealed the pivotal role of the Ccl4-Ccr5 signaling axis in the interaction between macrophages and natural killer cell, thereby intensifying neuroinflammatory responses and aberrant nociceptive signaling, which may contribute to apoptosis after SCI. Molecular docking and molecular dynamics simulations showed that quercetin had stable binding with Ccr5 and identified potential amino acid binding sites TYR-108 and PHE-109. In vivo experiments demonstrated that Ccr5 inhibitors and quercetin effectively improved the Basso mouse scale and mechanical withdrawal threshold score, concurrently attenuating spinal tissue apoptosis. Therefore, we propose that quercetin and Ccr5 inhibitors could potentially treat NP post-SCI by inhibiting the Ccl4-Ccr5 pathway and reducing apoptosis, providing new treatment avenues.