Tissue-resident memory T cells are epigenetically cytotoxic with signs of exhaustion in human urinary bladder cancer

Abstract

SummaryTissue‐resident memory T (TRM) cells are CD8+ T lymphocytes that reside in the tissues, including tumours. This T cell subset possesses a magnitude of cytotoxicity, but its epigenetic regulation has not been studied. Here, we investigate the impact of perforin DNA methylation in TRM cells and correlate it with their functional potential. Fifty‐three urothelial urinary bladder cancer (UBC) patients were recruited prospectively. The DNA methylation status of the perforin gene (PRF1) locus in TRM cells was investigated by pyrosequencing. Flow cytometry with ViSNE analysis and in‐vitro stimulation were used to evaluate TRM cell phenotypes. We discovered that tumour TRM cells have low DNA methylation in the PRF1 locus (32·9% methylation), which corresponds to increased numbers of perforin‐expressing TRM cells. Surprisingly, programmed cell death 1 (PD‐1) expression is high in tumour TRM cells, suggesting exhaustion. Following interleukin‐15 and T cell receptor stimulation, perforin and T‐bet expressions are enhanced, indicating that TRM cells from tumours are not terminally exhausted. Moreover, a high number of TRM cells infiltrating the tumours corresponds to lower tumour stage in patients. In conclusion, TRM cells from UBC tumours are epigenetically cytotoxic with signs of exhaustion. This finding identifies TRM cells as potential new targets for cancer immunotherapy.

Tissue-resident lymphocytes: from adaptive to innate immunity

“…47 In addition, a high number of T RM cells infiltrating the tumors is associated with lower tumor stage in patients with UBC. 48 In contrast, the accumulation of T RM cells in melanoma tumors has not been associated with prolonged survival or a better prognosis, suggesting that T RM cells are associated with a better prognosis in some cancers but not in others 106,107 ; T RM cells may have different local anti-tumor responses in different malignancies.…”

“…46 CD103 + CD39 + tumor-infiltrating CD8 + T cells have been found for six different malignancies including melanoma, lung cancer, head and neck squamous cell carcinoma (HNSCC), ovarian cancer, and rectal cancer, 47 and high numbers of perforin-expressing T RM cells are found in patients with urothelial urinary bladder cancer (UBC). 48 These findings indicate that (1) there may be substantial phenotypic heterogeneity among T RM cell subsets; (2) the tissue microenvironment and infection route can contribute to the regulation of phenotype and function of these cells; (3) phenotypic markers of T RM cells may differ between humans and mice; and (4) limitations in experimental techniques may confound our knowledge of T RM populations; cytometric identification based on phenotypic markers sometimes cannot represent a whole population. Therefore, identification of T RM cells based solely on the coexpression of CD69 and CD103 may not reliably identify all T RM cells.…”

“…Although the role of T RM cells in anti-viral immune responses has been extensively studied over the last decade, the role of T RM cells in anti-tumor immune responses has yet to be fully discerned. Recent findings have revealed an accumulation of CD103 + T RM cells in several human solid tumors including ovarian, [95][96][97] breast, 98 lung, [99][100][101][102] liver, 103 and urinary bladder 48 cancers. The abundance of these T RM cells has been associated with prolonged survival and better prognosis in patients with pulmonary squamous cell carcinoma (pSCC), 101 hepatocellular carcinoma (HCC), 103 triple-negative breast cancer (TNBC), 104 recurrent laryngeal squamous cell carcinoma (LSCC), 105 or HNSCC.…”

Targeting the Immune system and Epigenetic Landscape of Urological Tumors

“…A summary of most recent studies addressing combination strategies between epigenetics and immune environment in BlCa is presented in Table 1 [54][55][56][57][58][59][60][61][62][63][64]. Some studies have focused on obtaining methylation-based biomarkers with predictive value, namely concerning response to BCG-therapy [55][56][57].…”

“…Bergman et al [58] showed that an assessment of CD4+-cell lineage commitment by looking at specific CpGs methylation status could predict the outcome of BlCa patients, with demethylation of those sites (which include FOXP3, IFNG, IL13, and IL17A) associating with lower stage and, importantly, better response to neoadjuvant chemotherapy. Moreover, Hartana et al [59] explored the perforin gene PRF1, demonstrating that tissue-resident CD8-positive T cells show demethylation of this gene promoter, correlating with its higher expression, hence with more cytotoxic ability. Finally, Ramakrishnan et al [62] focused on EZH2 inhibition and its effects on the immune environment.…”