Clonally-Expanded, Thyrotoxic Autoimmune Mediator CD8+T cells Driven by IL21 Contribute to Checkpoint Inhibitor Thyroiditis [article]

Melissa G Lechner, Zikang Zhou, Aline T Hoang, Nicole Huang, Jessica Ortega, Lauren N Scott, Ho-Chung Chen, Anushi Y Patel, Rana Yakhshi Tafti, Kristy Kim, Willy Hugo, Pouyan Famini (+4 others)
2022 bioRxiv   pre-print
Autoimmune toxicity occurs in up to 60% of patients treated with immune checkpoint inhibitor (ICI) cancer therapy and is an increasing clinical challenge with the expanding use of these treatments. To date, human immunopathogenic studies of immune related adverse events (IRAEs) have relied upon sampling of circulating peripheral blood cells rather than affected tissues. Here, we directly obtained thyroid specimens from subjects with ICI-thyroiditis, one of the most common IRAEs, and compared
more » ... une infiltrates to those from subjects with spontaneous autoimmune Hashimoto's thyroiditis (HT) or no thyroid disease. Single cell RNA sequencing revealed a dominant, clonally expanded population of thyroid-infiltrating cytotoxic CXCR6+CD8+T cells ("CD8+autoimmune mediators") present in ICI-thyroiditis, but not HT or healthy controls. Furthermore, we identified a crucial role for interleukin 21, a cytokine secreted by intrathyroidal T follicular (Tfh) and T peripheral helper (Tph) cells, as a driver of these thyrotoxic CD8+autoimmune mediators. In the presence of IL21, human CD8+T cells acquired the autoimmune mediator phenotype with upregulation of cytotoxic molecules (IFNγ, granzyme); the chemokine receptor CXCR6; and thyrotoxic capacity. We validated these findingsin vivousing a novel mouse model of IRAEs, and further demonstrated that genetic blockade of IL21 signaling protected ICI-treated mice from thyroid immune infiltration. Taken together these studies reveal novel mechanisms and therapeutic targets by which IL21+Tfh/Tph cells drive thyrotoxic CD8+autoimmune mediators for the development of IRAEs in humans.
doi:10.1101/2022.12.18.517398 fatcat:ydp3u22zlffedlc65ijbkc7fiy