Presence of innate lymphoid cells in pleural effusions of primary and metastatic tumors: Functional analysis and expression of PD‐1 receptor

Abstract

The tumor microenvironment (TM) contains a wide variety of cell types and soluble factors capable of suppressing immune responses. While the presence of NK cells in pleural effusions (PE) has been documented, no information exists on the presence of other innate lymphoid cell (ILC) subsets and on the expression of programmed cell death‐1 (PD‐1) in NK and ILC. The presence of ILC was assessed in PE of 54 patients (n = 33 with mesothelioma, n = 15 with adenocarcinoma and n = 6 with inflammatory pleural diseases) by cell staining with suitable antibody combinations and cytofluorimetric analysis. The cytokine production of ILC isolated from both PE and autologous peripheral blood was analyzed upon cell stimulation and intracytoplasmic staining. We show that, in addition to NK cells, also ILC1, ILC2 and ILC3 are present in malignant PE and that the prevalent subset is ILC3. PE‐ILC subsets produced their typical sets of cytokines upon activation. In addition, we analyzed the PD‐1 expression on NK/ILC by multiparametric flow‐cytometric analysis, while the expression of PD‐1 ligand (PD‐L1) was evaluated by immunohistochemical analysis. Both NK cells and ILC3 expressed functional PD‐1, moreover, both tumor samples and malignant PE‐derived tumor cell lines were PD‐L1+ suggesting that the interaction between PD‐1+ILC and PD‐L1+tumor cells may hamper antitumor immune responses mediated by NK and ILC.

Peer Review #1 of "AURKB: a promising biomarker in clear cell renal cell carcinoma (v0.1)"

“…Yang et al (2018) have found that activation of intestinal immune network for IgA production signaling pathway promoted malignant behavior of tumor cells. Additionally, cytokine-cytokine receptor interaction was a significant immune signaling pathway, as it can modulate interaction of cytokines, thereby regulating occurrence and progression of cancers (Tumino et al, 2019;Nagarsheth, Wicha & Zou, 2017). Natural killer cell mediated cytotoxicity plays a vital role in modulating tumor microenvironment; their activation was closely related to the progression of tumors and prognosis of cancer patients (Malmberg et al, 2017;Chan et al, 2019;Bassani et al, 2019).…”

Exploiting Human NK Cells in Tumor Therapy

“…The expression of PD-1 by NK cells is controversial; indeed PB-NK cells derived from both healthy donors (HD) and neoplastic patients were originally reported to express low levels, if any, of PD-1. On the other hand, PD-1 bright NK cells were found in the PB and, more abundantly, in ascitic fluid of ovarian carcinoma patients (58), as well as in pleural effusions of patients with primary and metastatic tumors (19) and in Hodgkin lymphoma. Notably, both PD-1 mRNA and PD-1 protein are present in the cytoplasm of NK cells isolated from HD (59), although the molecular mechanisms leading to its surface expression are still poorly defined.…”

“…Donor NK cells and γδT cells, being present in the graft, are immediately available for the control of infections and leukemia relapses. Better clinical outcome, particularly in AML (15)(16)(17)(18)(19).…”

“…Although NK cells to be used in adoptive tumor therapy are usually derived from peripheral blood (PB), other sources have also been proposed. For example, the pleural fluid of primary or metastatic tumors contains high numbers of functional NK cells (19), which acquire strong cytotoxicity upon short culture intervals with IL-15 or IL-2 in vitro. Since large volumes of such fluids are routinely discarded, NK cells could be recovered and reinfused systemically or in the pleural cavity after in vitro culture with IL-15 (8).…”

“…While KIRs and NKG2A are constitutively expressed by mature NK cells, the expression of other inhibitory checkpoints involved in the homeostasis of immune responses, including PD-1, TIGIT, TIM-3, and CD96, is inducible (57). Such de novo-expressed checkpoint regulators have been shown to inhibit the NK cell function upon interaction with their ligands on tumor cells (19,58). We will focus on PD-1 since it is a major checkpoint receptor involved in the control of immune responses, and the therapeutic use of blocking antibodies disrupting the PD-1/PD-L1 axis represents a major breakthrough in the cure of highly aggressive tumors.…”