Biology subjects

Lamorte, S.

Publications and source records attributed to Lamorte, S..

3 recordsLinked to original sources

bioRxiv2024

STING agonists drive recruitment and intrinsic type I interferon responses in monocytic lineage cells for optimal anti-tumor immunity

The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway, a sensor of cytosolic DNA, orchestrates the production of pro-inflammatory cytokines, chemokines, and type I interferons (IFN-I), thereby contributing to spontaneous tumor surveillance. Intratumoral delivery of synthetic STING agonists induces IFN-I dependent tumor regression in preclinical cancer models and is being tested clinically. In this study, we investigate the role of monocytic lineage (MCs) cells in response to STING agonist induced IFN-I signaling. We show that CCR2-deficient mice, lacking inflammatory MCs in the periphery, or Lyz2-Cre-IFNAR1fl/fl mice in which IFN-I signaling in monocytes is reduced, exhibit impaired responses to STING agonist therapy of MC38 and/or B16F10 tumors. STING agonist treatment induced CCR5-dependent migration of MCs carrying tumor antigen from the tumor to the lymph nodes. Single-cell RNA sequencing of CD45+ cells from lymph nodes and tumors of mice in which half the hematopoietic cells lack the interferon alpha/beta receptor 1 (IFNAR1) revealed that STING agonist therapy induces intrinsic IFNAR1-dependent acquisition of an inflammatory monocytic cell phenotype distinct from inflammatory cDC and a reduction in macrophages with a pro-tumor TGF{beta}/angiogenesis transcriptome. IL-18 - IL-18R1 interaction was the top predicted interaction between monocytic lineage cells and CD8+T cells or NK cells. Blocking IL-18 reduced IFN-{gamma} production by CD8 T cells in LNs and decreased the therapeutic efficacy of STING agonist treatment in CCR2+/+ but not in CCR2-/- mice. These findings support a pivotal role for IL-18 producing inflammatory monocytic lineage cells in CD8 T cell control of melanoma following STING agonist treatment.

immunology↗

bioRxiv2023

Dabrafenib alters MDSC differentiation and function by activation of GCN2

The effect of targeted therapeutics on anti-cancer immune responses is poorly understood. The BRAF inhibitor dabrafenib has been reported to activate the integrated stress response (ISR) kinase GCN2, and the therapeutic effect has been partially attributed to GCN2 activation. Since ISR signaling is a key component of myeloid-derived suppressor cell (MDSC) development and function, we measured the effect of dabrafenib on MDSC differentiation and suppressive activity. Our data showed that dabrafenib attenuated MDSC ability to suppress T cell activity, which was associated with a GCN2-dependent block of the transition from monocytic progenitor to polymorphonuclear (PMN)-MDSCs and proliferative arrest resulting in PMN-MDSC loss. Transcriptional profiling revealed that dabrafenib-driven GCN2 activation altered metabolic features in MDSCs enhancing oxidative respiration, and attenuated transcriptional programs required for PMN development. Moreover, we observed a broad downregulation of transcriptional networks associated with PMN developmental pathways, and increased activity of transcriptional regulons driven by Atf5, Mafg, and Zbtb7a. This transcriptional program alteration underlies the basis for PMN-MDSC developmental arrest, skewing immature MDSC development towards monocytic lineage cells. In vivo, we observed a pronounced reduction in PMN-MDSCs in dabrafenib-treated tumor-bearing mice suggesting that dabrafenib impacts MDSC populations systemically and locally, in the tumor immune infiltrate. Thus, our data reveals transcriptional networks that govern MDSC developmental programs, and the impact of GCN2 stress signaling on the innate immune landscape in tumors, providing novel insight into potentially beneficial off target effects of dabrafenib.

immunology↗

bioRxiv2023

An Engineered 3D Co-culture Model of Primary Macrophages and Patient-Derived Tumour Cells to Explore Cellular Responses in the Graded Hypoxic Microenvironment of Pancreatic Cancer

In pancreatic ductal adenocarcinoma (PDAC), tumour associated macrophages (TAMs) are a heterogeneous immune cell population that interact with cancer cells to promote malignancy, chemo-resistance, and immunosuppression. Aside from TAMs, hypoxia is a prominent feature of PDAC that can rewire cells to survive and enhance malignancy in the tumour microenvironment (TME). Deciphering the interactions between macrophages, cancer cells and hypoxia could lead to the development of effective immune-targeted therapies for PDAC. However, there are only a few models that physiologically recapitulate the PDAC TME and allow for meaningful interrogation of cancer-immune cell interactions in hypoxia. Here, we develop a model of primary macrophages and PDAC patient organoid-derived cells by adapting TRACER, a paper-based, engineered 3D model that allows snapshot analysis of cellular response in hypoxia. In this study, we establish a direct co-culture method of primary macrophages and PDAC organoid cells in TRACER and demonstrate that TRACER co-cultures generate hypoxic gradients and show expected phenotypic responses to this hypoxic gradient. Moreover, we report for the first time in a human in vitro model that hypoxic macrophages exert a graded chemoprotective effect on gemcitabine-treated PDAC organoid cells, and that interactions between cancer cells and macrophages from the inner layers of TRACER indirectly attenuate the inflammatory response of donor-derived T-cells. Overall, the TRACER co-culture system is a novel, fully human 3D in vitro cancer-immune model for evaluating the response of macrophages and cancer cells in a hypoxic gradient.

bioengineering↗