Poster Presentation: Dr. Kathryn Regan

ABSTRACT

T cell motility exhibits age-related and mechanoresponsive signatures in pulmonary melanoma metastasis

Kathryn Regan1, Abdulrahman Kobayter1, Seyed Heydar Moravej2, Chanhong Min4, Jessica Daher1, Gabrielle Grifno1, Linzheng Shi1, Mohammad Fallahi-Sichani4, Jude Phillip4, Mohammad Rashidian2,3, Hadi T. Nia1

1: Department of Biomedical Engineering, Boston University
2: Department of Cancer Immunology and Virology, Dana Farber Cancer Institute
3: Division of Medical Sciences, Harvard Medical School
4: Department of Biomedical Engineering, Johns Hopkins University
5: Department of Biomedical Engineering, University of Virginia

Objectives: Understanding the motility of CD8+ cytotoxic T cells is of critical importance in the context of solid tumors, as greater T cell infiltration and killing activity is closely related to improved patient outcomes and therapeutic efficacy. However, traditional approaches to studying T cell movement and localization often depend on simplified systems that fail to capture the structural complexity of living tissue, or on static histology that lacks temporal resolution. To overcome these limitations, we examine the behavior of native, migratory CD8+ T cells responding to pulmonary metastasis within the intact, functional murine lung via the crystal ribcage (Fig. 1A). We probe both biological and mechanical influences on motility by examining how variations in age and mechanical strain (i.e., tidal volume) alter the immune cell motility.

Methods: Pulmonary melanoma (Yummer1.7-H2B-GFP) metastasis to the lung is induced in C57BL6/J mice (Fig. 1B). Native CD8+ T cells are labeled in situ using fluorophore-conjugated CD8-targeting nanobodies (Fig. 1C), before the lung is resected and imaged using the crystal ribcage, maintaining active ventilation and physiological function. Mice in aging studies are classified as Young (2-3 months) or Aged (20-24 months). For mechanical interventions, lungs are ventilated at low (0.1mL) or high (0.3mL) tidal volumes.

Results: We image native T cell migration in pulmonary melanoma metastasis, finding age reduces CD8+ T cell motility in metastatic melanoma both within intratumor regions (Fig. 1D) and in adjacent healthy tissue. Reductions in speed are further evident in extratumoral velocity profiles (Fig. 1E). Varying tidal volume in Young mice reveals notable reductions in T cell motility at the single cell (Fig. 1F) and experimental average (Fig. 1G) levels when lungs are ventilated at high tidal volume.

Conclusions: We quantify T cell motility in the physiologically relevant functional murine lung, finding age- and mechanically-related changes in T cell motility in pulmonary melanoma metastasis.