Nociceptor neurons affect cancer immunosurveillance

Solid tumours are innervated by nerve fibres that arise from the autonomic and sensory peripheral nervous systems(1-5). Whether the neo-innervation of tumours by pain-initiating sensory neurons affects cancer immunosurveillance remains unclear. Here we show that melanoma cells interact with nociceptor neurons, leading to increases in their neurite outgrowth, responsiveness to noxious ligands and neuropeptide release. Calcitonin gene-related peptide (CGRP)-one such nociceptor-produced neuropeptide-directly increases the exhaustion of cytotoxic CD8(+) T cells, which limits their capacity to eliminate melanoma. Genetic ablation of the TRPV1 lineage, local pharmacological silencing of nociceptors and antagonism of the CGRP receptor RAMP1 all reduced the exhaustion of tumour-infiltrating leukocytes and decreased the growth of tumours, nearly tripling the survival rate of mice that were inoculated with B16F10 melanoma cells. Conversely, CD8(+) T cell exhaustion was rescued in sensory-neuron-depleted mice that were treated with local recombinant CGRP. As compared with wild-type CD8(+) T cells, Ramp1(-/-) CD8(+) T cells were protected against exhaustion when co-transplanted into tumour-bearing Rag1-deficient mice. Single-cell RNA sequencing of biopsies from patients with melanoma revealed that intratumoral RAMP1-expressing CD8(+) T cells were more exhausted than their RAMP1-negative counterparts, whereas overexpression of RAMP1 correlated with a poorer clinical prognosis. Overall, our results suggest that reducing the release of CGRP from tumour-innervating nociceptors could be a strategy to improve anti-tumour immunity by eliminating the immunomodulatory effects of CGRP on cytotoxic CD8(+) T cells.

Automated summary

Solid tumors are innervated by nerve fibers that interact with melanoma cells and lead to increased growth and release of neuropeptides. One such neuropeptide, CGRP, directly induces CD8(+) T cell exhaustion, limiting their ability to eliminate melanoma. Inhibition of nerve fibers and CGRP signaling reduces exhaustion and tumor growth, while CD8(+) T cell exhaustion can be rescued by CGRP treatment. Additionally, intratumoral CD8(+) T cells expressing RAMP1 are more exhausted and overexpression of RAMP1 is associated with poorer clinical prognosis. Hence, reducing the release of CGRP from tumor-innervating nerve fibers could improve anti-tumor immunity.