GSE171638
Transcriptomic analysis of human regulatory (Treg) and effector (Teff) CD4+ memory T cells in the presence of oral cancer secretome versus not malignant secretome
The immune system plays a key role in the protective response against oral cancer; however, the tumour microenvironment (TME) is able to impair this anti-cancer response by modulating T helper (Th) responses and promoting an anti-inflammatory environment. Regulatory T cells (Tregs) and Th2 effector cells (Teff) have been associated with bad prognosis in oral squamous cell carcinoma (OSCC), however, it is unknown the main immunomodulatory mechanisms associated with the enrichment of these subsets in OSCC. We characterized Th-like lineages in Tregs and Teff and evaluated the main immunomodulatory changes induced by the TME in OSCC. Our phenotypic data revealed a higher distribution of tumour-infiltrating CCR8+ and Th2-like Treg in OSCC in comparison with non-malignant samples, whereas the percentages of Th1 cells were reduced in cancer. We then analyzed the direct effect of the TME by exposing T cell subsets to cancer secretomes and we observed that the OSCC secretome induced CCR8 expression and reduced cytokine production on both subsets. Transcriptomic analysis showed that the co-culture with OSCC secretome induced several gene changes associated with the vitamin D (VitD) signaling pathway in T cells. In addition, a proteomic analysis identified the presence of several proteins associated with prostaglandin E2 (PGE2) production by rapid membrane VitD signaling and an reduce presence of the VitD binding protein. Thus, we analyzed the effect of VitD and PGE2 and we observed that VitD promote a regulatory Th2-like responses and CCR8 expression, whereas PGE2 also modulate CCR8 but inhibited cytokine production in combination with VitD. Finally, we evaluated the presence of CCR8 ligand in OSCC and we observed higher presence of chemokine CCL18, which was also able to up regulate CCR8 in activated Th cells. Overall, our data showed that the immunomodulatory changes induced by the TME regarding CCR8 expression and regulatory Th2 phenotypes are associated with PGE2 mediated VitD signaling pathway and CCL18 expression in OSCC. Overall design: Pre-activated human regulatory and effetor CD4+ memory T cells from healthy donors were co-cultured with OSCC and control (non-malignant oral tissue) secretomes for 48h a 37ºC. Cell were then lysed on Trizol before transcriptomic analysis.