AREG and IFNG Define Subsets of γδ T Cells with Distinct Functional Properties in Human Cancer

Abstract

γδ T cells are a subset of innate T cells. They activate in minutes - rather than days - after stimulus and play a role in immune surveillance and anti-tumor responses. In general, the presence of γδ T cells in tumors is associated with good prognosis. However, variance in γδ T cell function across cancer types remains poorly understood. Here, we phenotype innate T cells, NK cells and conventional T cells in colon and endometrial cancers and healthy surrounding tissue by single cell sequencing. We identified that the proportions of the two γδ T cell subtypes, Vδ1 and Vδ2, change between normal tissues and tumor types. Subsequently, we identified that γδ T cells are more heterogenous in colorectal cancer (CRC) compared to endometrial cancer. In colon cancer, an amphiregulin (AREG) growth factor producing Vδ1 subset emerges. AREG was especially high in mismatch repair proficient (MMRp) type CRC patients, who have worse overall outcomes. While NK cells and innate lymphoid cells (ILC) also produced AREG, γδ T cells were the only cell type to increase AREG in response to malignancy compared to healthy mucosa. In contrast, endometrial tumors are infiltrated only by IFNγ+ cytotoxic Vδ1 γδ T cells. We show that AREG is produced in vitro and in vivo by isolated Vδ1 γδ T cells in response to human CRC cells. We found that AREG production by Vδ1 γδ T in vitro was the highest upon stimulation with IL1β and that IFNγ production was highest upon stimulation with IL15. Our findings hold promise for improving Vδ1 expansion protocols, a necessary step for generating γδ adoptive therapies that could treat solid malignancies and prevent metastatic disease.