Glial-Neuronal Crosstalk in the Ageing Murine Nodose Ganglion
Authors: Van Weperen Valerie , Devarajan Asokan , Littman Russell , Wang Kerry , Shannon Kassandra , Yang Xia , Vaseghi Marmar 
Published: May 2024

Background: Viscerosensory stimuli are transmitted from the peripheral nervous system to the central nervous system for processing, integration, and adequate motor response. Proper signal transmission is guarded by bidirectional interaction between neurons and glia and their dysfunction has been associated with sensory deficits in both aging and visceral disorders. However, compared to the central nervous system, the bidirectional interactions and pathways of communication between glia and neurons remain relatively unknown. The nodose ganglion (NG) houses the cell bodies of visceral sensory nerves, traveling from the periphery, via the vagus nerve, to the central nervous system. Autonomic remodeling in this ganglion is associated with many of the visceral diseases that increase in incidence with age. Given the increasing recognition of the importance of glia in neuronal function and neurotransmission, understanding their inter-cell dynamics are vital to appropriately interpret the neurophysiology of aging. Objectives: This study aimed to better understand subtypes of neurons and glia most involved in neuro-glial communication, the underlying genetic pathways involved in this crosstalk, and how these pathways change with age. Methods: Single-cell RNA sequencing (scRNAseq) was performed on NG of young (12 weeks) and old (16 months) mice (C57BL/6; N = 6 for both groups). Distinct satellite glial cell (SGC) and neuronal populations were clustered based on transcriptomic similarities using dimensionality reduction. Marker gene analyses were used for cell-type identification. Specific pathways responsible for glial-glial, neuron-neuron, and glial-neuronal cross talk, including secreted signaling, extracellular-matrix receptor interactions, and cell-cell contact, were assessed between the different glial and neuronal sub-clusters in young and aged NG. The R-packages Seurat and CellChat were used for cell clustering and cell-cell communication signaling pathway identification, respectively. Results: SGC ( N = 6835 cells total) were identified by high expression of glial-specific transcripts, S100b and Fabp7. Neurons ( N = 2027 neurons total) were identified by expression of Tubb3, Snap25, and Uchl1. Five distinct glial clusters and six distinct neuronal clusters were identified by expression of known functional marker genes. While neuron-to-neuron communication was limited, significant communication within glial subtypes and between glia and sensory neurons was noted, with residential SGCs being most central to this network. Residential SGC interactions were noted most significantly for excitatory, multimodal neuronal subtypes ( Vglut2+, TRPV1/2+, Piezo1/2+). The primary pathways driving this communication were trophic pathways (e.g., vascular endothelial growth factor , Tenascin C, and Thrombospondin-1). Surprisingly, while glia-glia signaling did not change with aging, glial-neuronal communication seemed to increase. Conclusion: These data suggest that, while there is limited communication between neurons in the nodose ganglia, there is extensive glial-glial and glial-neuronal communication. Resident SGCs and excitatory multimodal neurons, which are known to be critical in sensory neurotransmission, are central to this crosstalk. Aging was associated with increased glial-neuronal crosstalk, though the cause and effect of this increased glial-neuronal communication with age requires further investigation. Dr. Vaseghi is supported by NIH R01HL148190 and AHA 970217. VvW is supported by the NWO Rubicon grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.