Assessing the local roles of dendritic cells within the tumor microenvironment in lung cancer.
Dendritic cells (DCs) are the sentinel cells of the immune system, specialized in the presentation of antigens to T lymphocytes. Conventional DCs are heterogeneous and can be classified in type 1 DCs (DC1s) highly efficient in cross-presentation by MHCI of antigens to CD8+ T cells, and type 2 DCs (DC2s) highly efficient in antigen presentation by MHCII to CD4+ T cells. However, multiple evidences suggest that all DCs subsets can perform both types of antigen presentation to some extent. DCs infiltrate solid tumors and they have been shown to be important for the development of T cell responses against immunogenic tumors, or induced by immunotherapy by immune checkpoint blockade. Paradoxically, tolerogenic and immunosuppressive roles have also been ascribed to tumor-infiltrating DCs.
Upon innate sensing, DCs initiate a maturation process characterized by the acquisition of high levels of antigen-presentation (MHC-I and MHC-II), co-stimulatory (CD80, CD86, CD40), co-inhibitory (PDL1, PDL2, CD200) and adhesion molecules (ICAM1). Maturation-associated changes endow DCs with a unique ability to interact with T cells. Classically, mature DCs have been shown to undergo CCR7-dependent migration towards lymph nodes where they interact with antigen-specific naïve T lymphocytes. However, our lab has recently uncovered the accumulation of mature DCs residing in the tumors. We have analysed tumor-infiltrating DCs in a murine model of lung adenocarcinoma induced by the mutation of Kras oncogene and the inactivation of p53 tumor suppresor (KP). In the KP model, we found that a subset of DC2s expressing the C-type lectin MGL2 accumulates in the lungs of tumor-bearing mice and expresses high levels of maturation-associated molecules. We showed that this effect was dependent on the growth factor GM-CSF secreted by tumor cells.
This project intends to analyse the contribution of these “tumor-associated mature DCs” to the dynamics of tumor infiltrating lymphocytes.
Questions and aims of the internship:
- What is the contribution of MGL2+ DCs in anti-tumor T cell responses? To address this question, we will proceed to inducible and targeted cellular depletion (using transgenic mice expressing the diphteria toxin receptor MGL2DTR). T cell responses will be assessed in control or DC-depleted mice by single cell RNAseq characterization of tumor-infiltrating lymphocytes. This will provide an unbiased assessment of the impact of MGL2+ DCs subsets on the activation of T cell subsets.
To identify key signaling pathways at the DC-T cell interface, we will identify receptors ligands pairs candidates using expression data sets available in the lab using bioinformatics pipeline (NICHENET). These candidates will be validated for expression (in vivo by flow cytometry). Their functional contribution will be assessed using ex vivo DC-T cell co-cultures and agonists or inhibitors (blocking antibodies).
- Do DCs present antigen locally within tissues? To address this question, we will produce lung cryosections from new mice models (CCR7GFP/GFP x XCR1cre x RosaLSL-RFP) that are currently being bred in the lab, to identify mature DC subsets by confocal imaging. T cells will be visualized by antibodies against TCR, CD4, CD8 and transcription factors associated to T cell subsets (Foxp3, Tbet, TCF1, Tox e.g.).
- How do DCs respond to immunotherapy? Here, we will analyse if immunotherapy by checkpoint blockade (aPD1/aCTLA4) impacts on mature DC content within tumors, their phenotype and their ability to engage in contact with T cells locally, within the tumor-microenvironment.
Methodologies to be implemented in the internship:
Murine lung tumor models by intravenous engraftment of KP cell line.
Flow cytometry of tumor-associated DCs and CD4/CD8 T cells.
Bulk/single-cell RNA-seq of tumor-associated DCs and CD4/CD8 T cells.
Data analysis using R workflows.
Confocal imaging on cryosections.
A strong interest in murine models of cancer and animal experimentation is required.
Interest in bioinformatics and/or imaging will help.
- Epithelial Colonization promotes the Functional Diversification of Gut Dendritic Cells.
Rivera C.A., …, Guermonprez P ., Reis e Sousa C., Lecuit M., Moreau H.D., Helft J., Matic Vignjevic D., Villablanca E.J.V., Ana-Maria Lennon-Duménil. Immunity 2021.
- Tissue-resident FOLR2+ macrophages associate with tumor-infiltrating CD8+ T cells and with increased survival of breast cancer patients.
Ramos RN, …, Guermonprez P, Piaggio E, Helft J. Cell 2022.
- TIM4 expression by dendritic cells mediates uptake of tumor-associated antigens and anti-tumor responses.
Caronni N, …, Guermonprez P, Vermi W, Ginhoux F, Bicciato S, Nagata S, Benvenuti F. Nat Commun. 2021
- Transcriptional and Functional Analysis of CD1c+ Human DCs Identifies a CD163+ Subset
Priming CD8+CD103+ T Cells. Bourdely P, …, Helft J, Guermonprez P. Immunity 2020.
- Harnessing Mesenchymal Stromal Cells for the Engineering of Human Hematopoietic Niches.
Pievani A, …, Guermonprez P. Front Immunol 2021.
Laboratoire: Equipe “Antigen presentation by DCs to T lymphocytes »
Universite de Paris, CNRS ERL8252, INSERM1149, Centre de Recherche sur l’Inflammation, Faculte de Médecine Paris Diderot Site Bichat, 75018 Paris.