Analysis of matrisome expression patterns in murine and human dorsal root ganglia

Abstract

The extracellular matrix (ECM) is a dynamic structure of molecules that can be divided into six different categories and are collectively called the matrisome. The ECM plays pivotal roles in physiological processes in many tissues, including the nervous system. Intriguingly, alterations in ECM molecules/pathways are associated with painful human conditions and murine pain models. Nevertheless, mechanistic insight into the interplay of normal or defective ECM and pain is largely lacking. The goal of this study was to integrate bulk, single-cell, and spatial RNA sequencing (RNAseq) datasets to investigate the expression and cellular origin of matrisome genes in male and female murine and human dorsal root ganglia (DRG). Bulk RNAseq showed that about 65% of all matrisome genes were expressed in both murine and human DRG, with proportionally more core matrisome genes (glycoproteins, collagens, and proteoglycans) expressed compared to matrisome-associated genes (ECM-affiliated genes, ECM regulators, and secreted factors). Single cell RNAseq on male murine DRG revealed the cellular origin of matrisome expression. Core matrisome genes, especially collagens, were expressed by fibroblasts whereas matrisome-associated genes were primarily expressed by neurons. Cell–cell communication network analysis with CellChat software predicted an important role for collagen signaling pathways in connecting vascular cell types and nociceptors in murine tissue, which we confirmed by analysis of spatial transcriptomic data from human DRG. RNAscope in situ hybridization and immunohistochemistry demonstrated expression of collagens in fibroblasts surrounding nociceptors in male and female human DRG. Finally, comparing human neuropathic pain samples with non-pain samples also showed differential expression of matrisome genes produced by both fibroblasts and by nociceptors. This study supports the idea that the DRG matrisome may contribute to neuronal signaling in both mouse and human, and that dysregulation of matrisome genes is associated with neuropathic pain.

CD163+ macrophages monitor enhanced permeability at the blood–dorsal root ganglion barrier

“…To identify receptor–ligand interactions of biological importance for the two DRG macrophage subsets, we made use of recently published scRNA-seq profiles of all DRG cell types ( Avraham et al, 2020 ) and performed CellChat analysis ( Jin et al, 2021 ). We identified established cell–cell circuits such as neuronal to endothelial Vegfb - Vegfr1 signaling ( Kutcher et al, 2004 ) and endothelial to pericyte Pdgfb - Pdgfrb signaling ( Armulik et al, 2010 ) as well as proposed interactions such as fibroblast to SGC Col1a1/Col1a2-Sdc4 signaling ( Vroman et al, 2023 ; Table S5 ), validating the ability of this approach to identify biologically relevant pathways.…”

Communicating pain: emerging axonal signaling in peripheral neuropathic pain

“…These are principally glycoproteins (both collagenous and non-collagenous proteins) and proteoglycans secreted by cells in the vicinity. In the case of human and murine DRGs, the ECM elements are principally produced by fibroblasts and neuronal cells ( Vroman et al, 2023 ).…”

“…In addition, after peripheral nerve injury, some types of collagen (i.e., col4α5, col18α1, col19α1) are found upregulated at the damaged site ( Roumazeilles et al, 2018 ). Interestingly, even samples of people suffering from NeuP presented dysregulation of these ECM-genes ( Vroman et al, 2023 ).…”