Global characterization of T cells in non-small-cell lung cancer by single-cell sequencing

Abstract

Cancer immunotherapies have shown sustained clinical responses in treating non-small-cell lung cancer, but efficacy varies and depends in part on the amount and properties of tumor infiltrating lymphocytes. To depict the baseline landscape of the composition, lineage and functional states of tumor infiltrating lymphocytes, here we performed deep single-cell RNA sequencing for 12,346 T cells from 14 treatment-naïve non-small-cell lung cancer patients. Combined expression and T cell antigen receptor based lineage tracking revealed a significant proportion of inter-tissue effector T cells with a highly migratory nature. As well as tumor-infiltrating CD8 T cells undergoing exhaustion, we observed two clusters of cells exhibiting states preceding exhaustion, and a high ratio of "pre-exhausted" to exhausted T cells was associated with better prognosis of lung adenocarcinoma. Additionally, we observed further heterogeneity within the tumor regulatory T cells (Tregs), characterized by the bimodal distribution of TNFRSF9, an activation marker for antigen-specific Tregs. The gene signature of those activated tumor Tregs, which included IL1R2, correlated with poor prognosis in lung adenocarcinoma. Our study provides a new approach for patient stratification and will help further understand the functional states and dynamics of T cells in lung cancer.

The role and therapeutic implications of T cells in cancer of the lung

“…11 Antigen recognition in the presence of transforming growth factor b (TGFb) and IL-10, which are produced within the lung tumor environment, induces CD4 + T-cell differentiation into inducible Tregs (iTregs). 15 This is further corroborated by studies in NSCLC demonstrating an increased density of CD4 + and CD8 + T cells to Tregs to correlate to improved survival. 11 In NSCLC, increased levels of intratumoral and peripheral Tregs correlate with poorer prognosis and increased metastatic risk.…”

“…5,6 Conversely, engagement of coinhibitory receptors (immune checkpoints) such as programmed death-ligand 1 (PD-1), cytotoxic T-lymphocyte antigen-4 (CTLA-4) and lymphocyte activation gene-3 (LAG-3) provides negative regulation, mitigating excessive T-cell activation. 15 In addition, various environmental cytokines, such as interleukin-2 (IL-2), IL-15, IL-17, IL-10, and transforming growth factor b (TGFb), provide a further intrinsic layer of positive and negative feedback that modulates T-cell effector phenotype, functional quality and the antitumor immune cell response. 15 In addition, various environmental cytokines, such as interleukin-2 (IL-2), IL-15, IL-17, IL-10, and transforming growth factor b (TGFb), provide a further intrinsic layer of positive and negative feedback that modulates T-cell effector phenotype, functional quality and the antitumor immune cell response.…”

“…13,14 Once activated, Tregs can then exert their immunosuppressive function on effector CD4 + and CD8 + T cells, namely through further secretion of inhibitory cytokines, including TGFb, IL-10 and IL-35. 13,15 Interestingly, Wei and colleagues demonstrated that Tregs infiltrating into NSCLC tumors have a greater density of inhibitory molecule expression, such as CTLA-4, PD-1 and LAG-3, compared to peritumoral Tregs. 15 This is further corroborated by studies in NSCLC demonstrating an increased density of CD4 + and CD8 + T cells to Tregs to correlate to improved survival.…”

“…5,17 Despite this, research indicates these cells may be functionally tolerant to tumor antigen in lung cancer, characterised by dysregulated cytotoxic function and exhaustion. 15 In humans, increased CD8 + T cells infiltrating the tumor stroma of NSCLC are a positive prognostic marker, correlating to reduced metastatic risk. 15 In humans, increased CD8 + T cells infiltrating the tumor stroma of NSCLC are a positive prognostic marker, correlating to reduced metastatic risk.…”

Somatic mutation-associated T follicular helper cell elevation in lung adenocarcinoma

“…Our report of elevated Tfh in tumours by histology is corroborated by a recently-published single-cell transcriptomic analysis of 14 non-small-cell lung tumours, which revealed an increase of CXCL13 hi CD4 + T cells in tumour tissue compared to matched non-malignant lung tissue or peripheral blood from the same patient. 28 …”