Abstract 2341: Group 2 innate lymphoid cells influence pancreatic stromal cell composition in homeostasis and pancreatic cancer

Background: Group 2 Innate Lymphoid Cells (ILC2s) are tissue-resident innate immune cells critical in orchestrating type-2 immune responses. Cancer-associated fibroblasts are increasingly recognized as having important pro- and anti-tumorigenic roles. While type-2 immunity has been linked to fibrosis and tumor development, how ILC2s influence the stromal microenvironment in these settings is poorly understood. Here, we investigated the role of ILC2s on pancreatic stromal cell (PSC) behavior in healthy and tumor-bearing mice.

Methods: Naive, inflamed, and tumor-bearing pancreata of WT or ILC2-deficient mice were profiled by flow cytometry, histology, or multiplex immunofluorescence imaging. We assessed two-way communication between ILC2s and stromal cells using in silico analysis of single-cell RNAseq or in vitro coculture transcriptomic data. Putative crosstalk mechanisms were tested with in vitro and in vivo assays. Additionally, we performed two-photon microscopy of reporter mice pancreata and multiplex immunofluorescent imaging of tumor sections.

Results: Imaging studies show that ILC2s co-localize with IL-33+ stromal cells in the naïve, inflamed and tumor-bearing pancreas. In vivo and in vitro studies indicate that ILC2s are critical mediators of stromal cell proliferation and density in homeostatic and inflamed conditions, while influencing stromal cell-driven immune modulation in cancer. Single-cell transcriptomic analysis reveal distinct Il33+ and Il33- stromal cell clusters, which may engage in different crosstalk mechanisms with ILC2s, as determined by in silico inferential analysis, in vitro co-culture and in vivo studies.

Conclusion: ILC2s strongly influence stromal cell composition in both the healthy pancreas and pancreatic tumors. Given the importance attributed to the characteristic desmoplasia of pancreatic tumors, ILC2-driven modulation of the stromal compartment may affect tumor progression.

Citation Format: Thomas Yip, Sheng Lee, Julie Stockis, Celine Garcia, Shwetha Raghunathan, Bram Lim, Silvain Pinaud, Shaun Png, Timotheus Halim. Group 2 innate lymphoid cells influence pancreatic stromal cell composition in homeostasis and pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2341.

ILC2-driven innate immune checkpoint mechanism antagonizes NK cell anti-metastatic function in the lung

Metastasis constitutes the primary cause of cancer-related deaths, with the lung being a commonly affected organ. We found that activation of lung-resident group 2 innate lymphoid cells (ILC2s) orchestrated suppression of natural killer (NK) cell-mediated innate antitumor immunity, leading to increased lung metastases and mortality. Using multiple models of lung metastasis, we show that interleukin (IL)-33-dependent ILC2 activation in the lung is involved centrally in promoting tumor burden. ILC2-driven innate type 2 inflammation is accompanied by profound local suppression of interferon-γ production and cytotoxic function of lung NK cells. ILC2-dependent suppression of NK cells is elaborated via an innate regulatory mechanism, which is reliant on IL-5-induced lung eosinophilia, ultimately limiting the metabolic fitness of NK cells. Single-cell and bulk transcriptomic analysis of lung NK cells reveals that post-transcriptional regulation likely accounts for IL-33-ILC2 dependent suppression of NK cell function. Using mass-spectrometry imaging (MSI) of the lungs of 13 C-Glucose infused mice, and metabolite profiling of ex vivo lung cultures, we find that IL-33 drives localized depletion of glucose via ILC2-dependent recruitment of highly glycolytic eosinophils, which can directly suppress lung NK cell function. Therapeutic targeting of IL-33 or IL-5 reversed NK cell suppression and alleviated cancer burden. Thus, we reveal an important function of IL-33 and ILC2s in promoting tumor metastasis via their capacity to suppress innate type 1 immunity.

ILC2-driven innate immune checkpoint mechanism antagonizes NK cell antimetastatic function in the lung

Metastasis constitutes the primary cause of cancer-related deaths, with the lung being a commonly affected organ. We found that activation of lung-resident group 2 innate lymphoid cells (ILC2s) orchestrated suppression of natural killer (NK) cell-mediated innate antitumor immunity, leading to increased lung metastases and mortality. Using multiple models of lung metastasis, we show that interleukin (IL)-33-dependent ILC2 activation in the lung is involved centrally in promoting tumor burden. ILC2-driven innate type 2 inflammation is accompanied by profound local suppression of interferon-γ production and cytotoxic function of lung NK cells. ILC2-dependent suppression of NK cells is elaborated via an innate regulatory mechanism, which is reliant on IL-5-induced lung eosinophilia, ultimately limiting the metabolic fitness of NK cells. Therapeutic targeting of IL-33 or IL-5 reversed NK cell suppression and alleviated cancer burden. Thus, we reveal an important function of IL-33 and ILC2s in promoting tumor metastasis via their capacity to suppress innate type 1 immunity.