RNA profiling of human dorsal root ganglia reveals sex differences in mechanisms promoting neuropathic pain

Abstract

Neuropathic pain is a leading cause of high impact pain, is often disabling and is poorly managed by current therapeutics. Here we focused on a unique group of neuropathic pain patients undergoing thoracic vertebrectomy where the dorsal root ganglia is removed as part of the surgery allowing for molecular characterization and identification of mechanistic drivers of neuropathic pain independently of preclinical models. Our goal was to quantify whole transcriptome RNA abundances using RNA-seq in pain-associated human dorsal root ganglia from these patients, allowing comprehensive identification of molecular changes in these samples by contrasting them with non-pain associated dorsal root ganglia. We sequenced 70 human dorsal root ganglia, and among these 50 met inclusion criteria for sufficient neuronal mRNA signal for downstream analysis. Our expression analysis revealed profound sex differences in differentially expressed genes including increase of IL1B, TNF, CXCL14, and OSM in male and including CCL1, CCL21, PENK and TLR3 in female dorsal root ganglia associated with neuropathic pain. Co-expression modules revealed enrichment in members of JUN-FOS signalling in males, and centromere protein coding genes in females. Neuro-immune signalling pathways revealed distinct cytokine signalling pathways associated with neuropathic pain in males (OSM, LIF, SOCS1) and females (CCL1, CCL19, CCL21). We validated cellular expression profiles of a subset of these findings using RNAscope in situ hybridization. Our findings give direct support for sex differences in underlying mechanisms of neuropathic pain in patient populations.

The matrisome of the murine and human dorsal root ganglion: a transcriptomal approach

“…When interrogating previously published bulk RNAseq data from human DRG for human matrisome genes, a similar trend was observed [33]. Overall, 64±0.87% of the 1,027 human matrisome genes were expressed (TPM > 0.9; male: n = 11, female: n = 4).…”

“…Orthologues between murine and human datasets have been highlighted in the color corresponding to the matrisome categories. Human bulk RNAseq data was previously published [33].…”

Fragile X Mental Retardation Protein (FMRP) expression in human nociceptor axons of the spinal dorsal horn— Implications for RNA targeting and localized translation

“…The copyright holder for this preprint this version posted September 17, 2022. ; https://doi.org/10.1101/2022.09.15.508178 doi: bioRxiv preprint are highly expressed in human nociceptors (Harte et al, 2018;Iyengar et al, 2017;Latremoliere & Woolf, 2009;Ray et al, 2022;Sluka & Clauw, 2016;. FMRP is present along the extent of centrally-projecting human nociceptor axons targeting substantia gelatinosa.…”

“…In hippocampus, recent findings demonstrate that axonal FMRP-RNPs couple circuit activity to axonal protein synthesis and long-term presynaptic remodeling required for LTP (Monday et al, 2022b). In rodent and human brain circuits, FMRP-RNPs contain mRNAs critical for bouton formation and synaptic vesicle dynamics that are also highly expressed in subsets of human nociceptors (Akins et al, 2017; Bamji et al, 2003, 2006; Chyung et al, 2018; Ray et al, 2022; Sun et al, 2009; Sun & Bamji, 2011; Tavares-Ferreira, Shiers, et al, 2022; Taylor et al, 2013). Long-term nociceptor plasticity also requires axonal translation, a well-characterized mechanism in their peripheral arbors that reorganizes the local proteome and enhances local signaling (L. F. Ferrari et al, 2015; Khoutorsky & Price, 2018; Price & Géranton, 2009; Reichling & Levine, 2009).…”

“…This pairs synaptic activity with local synthesis of receptor/channel subunits (e.g., AMPAR; Kv4.2) and internalization machineries (e.g., Arc; SYNGAP1; SAPAP3) to modulate dendritic channel and receptor surface expression (Antar et al, 2004;Bagni & Zukin, 2019;Bear et al, 2004;Niere et al, 2012;Paul et al, 2019;Routh et al, 2013;Wang et al, 2008Wang et al, , 2010. These receptors/channels play critical roles in chronic pain-associated spinal circuit activity, and these mRNAs are highly expressed in human nociceptors (Harte et al, 2018;Iyengar et al, 2017;Latremoliere & Woolf, 2009;Ray et al, 2022;Sluka & Clauw, 2016;. FMRP is present along the extent of centrally-projecting human nociceptor axons targeting substantia gelatinosa.…”