Intravital Imaging of Adoptive T-Cell Morphology, Mobility and Trafficking Following Immune Checkpoint Inhibition in a Mouse Melanoma Model.

Abstract

Efficient T-cell targeting, infiltration and activation within tumors is crucial for successful adoptive T-cell therapy. Intravital microscopy is a powerful tool for the visualization of T-cell behavior within tumors, as well as spatial and temporal heterogeneity in response to immunotherapy. Here we describe an experimental approach for intravital imaging of adoptive T-cell morphology, mobility and trafficking in a skin-flap tumor model, following immune modulation with immune checkpoint inhibitors (ICIs) targeting PD-L1 and CTLA-4. A syngeneic model of ovalbumin and mCherry-expressing amelanotic mouse melanoma was used in conjunction with adoptively transferred OT-1+ cytotoxic T-cells expressing GFP to image antigen-specific live T-cell behavior within the tumor microenvironment. Dynamic image analysis of T-cell motility showed distinct CD8+ T-cell migration patterns and morpho-dynamics within different tumor compartments in response to ICIs: this approach was used to cluster T-cell behavior into four groups based on velocity and meandering index. The results showed that most T-cells within the tumor periphery demonstrated Lévy-like trajectories, consistent with tumor cell searching strategies. T-cells adjacent to tumor cells had reduced velocity and appeared to probe the local environment, consistent with cell-cell interactions. An increased number of T-cells were detected following treatment, traveling at lower mean velocities than controls, and demonstrating reduced displacement consistent with target engagement. Histogram-based analysis of immunofluorescent images from harvested tumors showed that in the ICI-treated mice there was a higher density of CD31+ vessels compared to untreated controls and a greater infiltration of T-cells towards the tumor core, consistent with increased cellular trafficking post-treatment.

• Authors: Doreen Lau, Fabien Garçon, Anita Chandra, Laura M Lechermann, Luigi Aloj, Edwin R Chilvers, Pippa G Corrie, Klaus Okkenhaug, Ferdia A Gallagher
• Journal: Frontiers in immunology (Front Immunol) Vol. 11 Pg. 1514 ( 2020) ISSN: 1664-3224 [Electronic] Switzerland
• PMID: 32793206 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2020 Lau, Garçon, Chandra, Lechermann, Aloj, Chilvers, Corrie, Okkenhaug and Gallagher.

Chemical References

• Antigens, Neoplasm
• Immune Checkpoint Inhibitors

Topics

• Adoptive Transfer
• Animals
• Antigens, Neoplasm (immunology)
• Cell Line, Tumor
• Cell Movement (immunology)
• Combined Modality Therapy
• Disease Models, Animal
• Fluorescent Antibody Technique (methods)
• Image Processing, Computer-Assisted
• Immune Checkpoint Inhibitors (pharmacology)
• Immunotherapy, Adoptive
• Lymphocyte Activation (immunology)
• Melanoma, Experimental (diagnostic imaging, etiology, therapy)
• Mice
• Molecular Imaging (methods)
• T-Cell Antigen Receptor Specificity
• T-Lymphocytes (cytology, drug effects, immunology, metabolism)