Pre-metastatic neutrophils directly support highly tumourigenic breast cancer cells during lung metastasis via a leukotriene-ERK1/2 axis

Evidence is mounting that cancer development and progression depends on a supporting microenvironment or stroma. Pro-tumourigenic and pro-metastatic properties of inflammation are long recognised and systemic or intra-tumoural presence of the cellular inflammatory mediators neutrophils shows strong associations with poor prognosis in the clinic. Thus, we were prompted to investigate the contribution of neutrophils to tumourigenesis and metastasis. Taking advantage of mouse models for lung metastatic breast cancer, we find neutrophils to be the predominant inflammatory component to strongly accumulate in the pre-metastatic organ of tumour-bearing mice prior to metastatic colonisation by cancer cells. Preventing increased neutrophil presence in the lung during metastasis initiation resulted in a pronounced decrease of metastatic burden. In fact, we unravelled a novel function of mammary tumour-induced neutrophils at the distant site to directly aid proliferation and initiation of metastatic outgrowth of cancer cells. Neutrophils specifically promote the intrinsically highly potent metastasis-initiating subpopulation of mammary cancer cells during initiation of metastatic lung colonisation via secretion of Alox5 metabolites, the lipid mediators leukotrienes. Engagement of leukotriene receptors with their ligands induced cell proliferation by activation of ERK1/2 kinases in mammary cancer cells. Leukotriene receptor expression is strongly enriched on metastasis-initiating cells and makes them susceptible to the neutrophil-derived proliferation-inducing signals leading to their expansion at the metastatic site. In fact, leukotriene receptor expression itself might represent a novel marker to identify highly tumourigenic cancer stem cells. Interference with neutrophil-derived Alox5 metabolites/leukotrienes holds potential to weaken the highly potent cancer stem cell-like subpool, the main cellular cause of metastasis initiation and relapse. Importantly, genetic or pharmacologic block of the Alox5 enzyme prevents the proliferation and expansion of metastasis-initiating cells and subsequently the metastasis-promoting activity of neutrophils. The Alox5 inhibitor Zileuton, which is routinely used in the clinic to treat asthmatic patients, significantly reduced lung metastasis in three mouse models of breast cancer. This observation, together with expression of leukotriene receptors in the majority of examined human breast cancers and lymph node metastases, suggests a promising novel therapeutic approach targeting the tumour stroma to limit metastatic progression. In summary, we found neutrophils, an inflammatory component of the metastatic microenvironment, to act pro-metastatic. Neutrophils specifically promote early events of metastasis initiation at the distant site by providing a direct, proliferation-inducing signal to intrinsically highly potent metastasis-initiating cells. Interference with the neutrophil-leukotriene-ERK1/2 axis-dependent support might hold great potential to be exploited in the clinic. Please note that part of the data contained in this PhD thesis was first published by the Nature Publishing Group (Wculek and Malanchi, 2015)

Metabolism of tissue macrophages in homeostasis and pathology.

Cellular metabolism orchestrates the intricate use of tissue fuels for catabolism and anabolism to generate cellular energy and structural components. The emerging field of immunometabolism highlights the importance of cellular metabolism for the maintenance and activities of immune cells. Macrophages are embryo- or adult bone marrow-derived leukocytes that are key for healthy tissue homeostasis but can also contribute to pathologies such as metabolic syndrome, atherosclerosis, fibrosis or cancer. Macrophage metabolism has largely been studied in vitro. However, different organs contain diverse macrophage populations that specialize in distinct and often tissue-specific functions. This context specificity creates diverging metabolic challenges for tissue macrophage populations to fulfill their homeostatic roles in their particular microenvironment and conditions their response in pathological conditions. Here, we outline current knowledge on the metabolic requirements and adaptations of macrophages located in tissues during homeostasis and selected diseases.SKW and the project that gave rise to these results received support in the form of a fellowship from the La Caixa Foundation (ID 100010434). The fellowship code is LCF/BQ/ PR20/11770008. GD is supported by a European Molecular Biology Organization Longterm Fellowship (ALTF 379-2019). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie SkłodowskaCurie grant agreement No. 892965. IHM is supported by a La Caixa INPhINIT fellowship (ID 100010434, fellowship code: LCF/BQ/IN17/11620074). Work in the DS laboratory is funded by the CNIC, by the European Research Council (ERC-2016-Consolidator Grant 725091), by the Agencia Estatal de Investigación (PID2019-108157RB), by the Comunidad de Madrid (B2017/BMD-3733 Immunothercan-CM), by Atresmedia (Constantes y Vitales prize), by the Fondo Solidario Juntos (Banco Santander), and by the Fundació La Marató de TV3 (201723). The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the MICINN and the Pro CNIC Foundation.S

Neutrophils in cancer: neutral no more

Neutrophils are indispensable antagonists of microbial infection and facilitators of wound healing. In the cancer setting, a newfound appreciation for neutrophils has come into view. The traditionally held belief that neutrophils are inert bystanders is being challenged by the recent literature. Emerging evidence indicates that tumours manipulate neutrophils, sometimes early in their differentiation process, to create diverse phenotypic and functional polarization states able to alter tumour behaviour. In this Review, we discuss the involvement of neutrophils in cancer initiation and progression, and their potential as clinical biomarkers and therapeutic targets

Tumor cell dormancy

Metastasis is the primary cause of death in cancer patients and current treatments fail to provide durable responses. Efforts to treat metastatic disease are hindered by the fact that metastatic cells often remain dormant for prolonged intervals of years, or even decades. Tumor dormancy reflects the capability of disseminated tumor cells (DTCs), or micrometastases, to evade treatment and remain at low numbers after primary tumor resection. Unfortunately, dormant cells will eventually produce overt metastasis. Innovations are needed to understand metastatic dormancy and improve cancer detection and treatment. Currently, few models exist that faithfully recapitulate metastatic dormancy and metastasis to clinically relevant tissues, such as the bone. Herein, we discuss recent advances describing genetic cell-autonomous and systemic or local changes in the microenvironment that have been shown to endow DTCs with properties to survive and eventually colonize distant organs

Effective cancer immunotherapy by natural mouse conventional type-1 dendritic cells bearing dead tumor antigen

BACKGROUND: The manipulation of dendritic cells (DCs) for cancer vaccination has not reached its full potential, despite the revolution in cancer immunotherapy. DCs are fundamental for CD8+ T cell activation, which relies on cross-presentation of exogenous antigen on MHC-I and can be fostered by immunogenic cancer cell death. Translational and clinical research has focused on in vitro-generated monocyte-derived DCs, while the vaccination efficacy of natural conventional type 1 DCs (cDC1s), which are associated with improved anti-tumor immunity and specialize on antigen cross-presentation, remains unknown. METHODS: We isolated primary spleen mouse cDC1s and established a protocol for fast ex vivo activation and antigen-loading with lysates of tumor cells that underwent immunogenic cell death by UV irradiation. Natural tumor antigen-loaded cDC1s were transferred and their potential for induction of endogenous CD8+ and CD4+ T cell responses in vivo, cancer prevention and therapy were assessed in three grafted cancer models. Further, we tested the efficacy of natural cDC1 vaccination in combination and comparison with anti-PD-1 treatment in two "wildtype" tumor models not expressing exogenous antigens. RESULTS: Herein, we reveal that primary mouse cDC1s ex vivo loaded with dead tumor cell-derived antigen are activated and induce strong CD8+ T cell responses from the endogenous repertoire upon adoptive transfer in vivo through tumor antigen cross-presentation. Notably, cDC1-based vaccines enhance tumor infiltration by cancer-reactive CD8+ and CD4+ T cells and halt progression of engrafted cancer models, including tumors that are refractory to anti-PD-1 treatment. Moreover, combined tumor antigen-loaded primary cDC1 and anti-PD-1 therapy had strong synergistic effects in a PD-1 checkpoint inhibition susceptible cancer model. CONCLUSIONS: This preclinical proof-of-principle study is first to support the therapeutic efficacy of cancer immunotherapy with syngeneic dead tumor cell antigen-loaded mouse cDC1s, the equivalents of the human dendritic cell subset that correlates with beneficial prognosis of cancer patients. Our data pave the way for translation of cDC1-based cancer treatments into the clinic when isolation of natural human cDC1s becomes feasible.Work in the DS laboratory is funded by the CNIC and grant SAF2016–79040-R from Ministerio de Ciencia, Innovación e Universidades (MCIU), Agencia Estatal de Investigación and Fondo Europeo de Desarrollo Regional (FEDER); B2017/BMD-3733 Immunothercan-CM from Comunidad de Madrid; RD16/0015/0018-REEM from FIS-Instituto de Salud Carlos III, MICINN and FEDER; Acteria Foundation; Constantes y Vitales prize (Atresmedia); La Marató de TV3 Foundation (201723); and the European Research Council (ERC-2016-Consolidator Grant 725091). Work at the IM laboratory is funded by grants from MCIU (SAF2014–52361-R and SAF2017–83267-C2–1-R) and by European Commission VII Framework and Horizon 2020 programs (AICR), Fundación de la Asociación Española Contra el Cáncer (AECC), and Fundación BBVA. SKW is supported by a European Molecular Biology Organization Long-term Fellowship (grant ALTF 438–2016) and a CNIC-International Postdoctoral Program Fellowship (grant 17230–2016). SCK is a recipient of a FPU fellowship (FPU16/03142) from the Spanish Ministry of Education, Culture and Sports. IM and DS labs are funded by the European Commission (635122-PROCROP H2020). The CNIC is supported by the MCIU and the Pro-CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015-0505). AGRADECIENTOS: ProCNIC; Severo Ochoa (SEV-2015-0505)S

Women in STEM Becoming Independent: Our Shared Motivation and Enthusiasm Are Our Driving Force

This year at JEM, we are highlighting women in science by sharing their stories and amplifying their voices. In this Viewpoint, we hear from a cross section of women, across multiple research fields, discussing their science and the process of setting up a lab as an independent researcher

Immunotherapy with conventional type-1 dendritic cells induces immune memory and limits tumor relapse

The potential of dendritic cell (DC) vaccination against cancer is not fully achieved. Little is known about the precise nature of the anti-cancer immune response triggered by different natural DC subsets and their relevance in preventing postsurgical tumor recurrence. Here, we use mouse splenic conventional DC1s (cDC1s) or cDC2s pulsed with tumor cell lysates to generate DC vaccines. cDC1-based vaccination induces a stronger effector and memory CD4+ and CD8+ anti-tumor T cell response, leading to a better control of tumors treated either therapeutically or prophylactically. Using an experimental model of tumor relapse, we show that adjuvant or neoadjuvant cDC1 vaccination improves anti-tumor immune memory, particularly by increasing the infiltrates of CD4+ tissue resident memory (Trm) and CD8+ memory T cells. This translates into complete prevention of tumor relapses. Moreover, elevated abundance of cDC1s positively correlates with CD4+ Trm presence, and both associate with enhanced survival in human breast cancer and melanoma. Our findings suggest that cDC1-based vaccination excels at immune memory induction and prevention of cancer recurrence

Oxidative phosphorylation selectively orchestrates tissue macrophage homeostasis

We are grateful to N.-G. Larsson, F. Sa´ nchez-Madrid, G. Sabio, R.D. Palmiter, E. Gottlieb, C.T.Moraes, and M.A. del Pozofor sharing essential reagents.We thank S. Iborra, his team, M. Sa´ nchez-A´ lvarez, I. Nikolic, and members of the D.S. laboratory for discussions and critical reading of the manuscript. We thank the staff at the CNIC technical units; foremost the animal, cellomics, histology, metabolomics, genomics,microscopy, and bioinformaticsfacilities; and the SIdI of the Universidad Auto´ noma de Madrid for technical support. This project was supported by the ‘‘la Caixa’’ Foundation (ID 100010434) Postdoctoral Junior Leader Fellowship code LCF/BQ/PR20/11770008 (S.K.W.); ‘‘la Caixa’’ Foundation (ID 100010434) INPhINIT Fellowship code LCF/BQ/IN17/11620074 (I.H.-M.); Spanish Ministry of Education FPU fellowship code FPU20/01418 (M.G.); Ministerio de Ciencia e Innovacio´ n (MCIN) PID2019-104233RB-100/AEI/10.13039/ 501100011033 (S.L.); and NIH grants P01AG049665-08, RO1A148190, and P01HL154998 (N.S.C.). The J.A.E. laboratory is supported by the CNIC and a grant by Ministerio de Ciencia, Innovacio´ n y Universidades (MCNU); Agencia Estatal de Investigacio´ n (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) (RTI2018-099357-B-I00); the Biomedical Research Networking Center on Frailty and Healthy Ageing (CIBERFES-ISCiii-CB16/10/00289); and the HFSP agency (RGP0016/2018). Work in the D.S. laboratory is funded by the CNIC; by the European Union’s Horizon 2020 research and innovation program under grant agreement ERC-2016-Consolidator grant 725091; by Spanish Ministerio de Ciencia e Innovacio´ n PID2019-108157RB/AEI/ and CPP2021-008310/AEI/10.13039/ 501100011033; by Comunidad de Madrid (P2022/BMD-7333 INMUNOVARCM); and by ‘‘la Caixa’’ Foundation (LCF/PR/HR20/00075 and LCF/PR/HR22/ 00253). The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the MICINN, and the Pro CNIC Foundation and is a Severo Ochoa Center of Excellence (CEX2020-001041-S funded by MCIN/AEI/10.13039/501100011033).S

Depletion of conventional type-1 dendritic cells in established tumors suppresses immunotherapy efficacy.

The ability of conventional type-1 dendritic cells (cDC1) to cross-present tumor antigens to CD8+ T cells is critical for the induction of antitumor cytotoxic T lymphocytes. Mice that are constitutively deficient in cDC1 cells have been reported to fail to respond to immunotherapy strategies based on checkpoint inhibitors. However, further work is needed to clarify the precise time during immunotherapy treatment that cDC1 cells are required for the beneficial effect of treatment. Here, we used a refined XCR1-DTR-Venus transgenic mouse model to acutely deplete cDC1 cells and trace their behavior using intravital microscopy. Diphtheria toxin-mediated cDC1 depletion prior to immunotherapy treatment with anti-PD-1 and/or anti-CD137 immunostimulatory monoclonal antibodies (mAbs) completely ablated anti-tumor efficacy. The efficacy of adoptive T-cell therapy was also hampered by prior cDC1 depletion. After the onset of immunotherapy treatment, depletion of cDC1s only moderately reduced the therapeutic efficacy of anti-PD-1 and anti-CD137 mAbs. Intravital microscopy of liver-engrafted tumors revealed changes in the intratumoral behavior of cDC1 cells in mice receiving immunotherapy, and treatment with diphtheria toxin to deplete cDC1s impaired tumor T-cell infiltration and function. These results reveal that the functional integrity of the cDC1 compartment is required at the onset of various immunotherapies to successfully treat established tumors.This work was supported by Spanish Ministry of Economy and Competitiveness and Spanish Ministry of Research (MINECO SAF2014-52361-R and SAF 2017-83267-C2-1R and PID2020-112892RB-100, PID2020-113174-RA-100 [AEI/FEDER,UE], financed by MCIN/AEI/10.13039/501100011033), Cancer Research Institute under the CRI-CLIP, Asociación Española Contra el Cancer (AECC) Foundation under Grant GCB15152947MELE, Joint Translational Call for Proposals 2015 (JTC 2015) TRANSCAN-2 (code: TRS-2016-00000371), projects PI14/01686, PI13/00207, PI16/00668, PI19/01128, funded by Instituto de Salud Carlos III and co-funded by European Union (ERDF, “A way to make Europe”), European Commission within the Horizon 2020 Programme (PROCROP - 635122), Gobierno de Navarra Proyecto LINTERNA Ref: 0011–1411, Mark Foundation, Fundación BBVA and Fundación Olga Torres. AT is supported by the Ramon y Cajal program from the Spanish Ministry of Science (RYC2019-026406-I financiada por MCIN/AEI /10.13039/501100011033 y por El FSE invierte en tu futuro).S