Abstract:
Barrier tissue immune responses are regulated, in part, by nociceptors. Nociceptor ablation alters local immune responses at peripheral sites and within draining lymph nodes (LNs). Nevertheless, the mechanisms and significance of nociceptor-dependent modulation of LN function are unknown. Using high-resolution imaging, viral tracing, single-cell transcriptomics, and optogenetics, we identified and functionally tested a sensory neuro-immune circuit that is responsive to lymph-borne inflammatory signals. Transcriptomic profiling revealed that multiple sensory neuron subsets – predominantly peptidergic nociceptors – innervate LNs, distinct from those innervating surrounding skin. To uncover LN-resident cells that may interact with LN-innervating sensory neurons, we generated a LN single-cell transcriptomic atlas and nominated nociceptor target populations and interaction modalities. Optogenetic stimulation of LN-innervating sensory fibers triggered rapid transcriptional changes within the predicted interacting cell types, particularly endothelium, stromal cells, and innate leukocytes . Thus, a unique population of sensory neurons monitors peripheral LNs and may locally regulate gene expression.
Dataset:
We defined the composition of LN-innervating sensory neurons using scRNA-seq (SMART-Seq2). We injected a Cre-expressing recombinant adeno-associated virus, AAV2/1-Cre (a serotype with broad tropism towards DRG neurons (Kuehn et al., 2019; Mason et al., 2010) into the right iLN of Rosa26LSL-tdTomato/LSL-tdTomato mice carrying a Cre-dependent tdTomato reporter. Upon entry into sensory fibers, this non-replicating virus travels retrogradely to the cell body in DRGs where virally encoded Cre recombinase induces expression of tdTomato. Following unilateral iLN injection, robust tdTomato expression was observed in neurons in the ipsilateral last thoracic (T13) and first lumbar (L1) DRGs, which supply the inguinal region (Takahashi and Nakajima, 1996). TdTomato labeling at the site of injection was primarily concentrated within the injected iLN, indicating spatial confinement of the injected material. We harvested ipsilateral T13 and L1 DRGs from AAV2/1-Cre injected Rosa26LSL-tdTomato/LSL-tdTomato animals, manually isolated individual tdTomato+ neurons, and performed scRNA-seq on 52 LN-innervating sensory neurons (Hempel et al., 2007, Picelli et al., 2014; Trombetta et al., 2014). As a control, we also profiled 31 skin-innervating neurons from 4 Rosa26LSL-tdTomato/LSL-tdTomato mice that were retrogradely labeled by intradermal AAV2/1-Cre injection.
Contributors:
Siyi Huang #, Carly G. K. Ziegler #, John Austin, Najat Mannoun, Marko Vukovic, Jose Ordovas-Montanes, Alex K. Shalek*, and Ulrich H. von Andrian*
# These authors contributed equally to this work
* These senior authors contributed equally to this work
BioRxiv: https://www.biorxiv.org/content/10.1101/833509v1
Peer-reviewed updated version: https://www.cell.com/cell/fulltext/S0092-8674(20)31564-6
