Biomechanical regulation of CD8⁺ T cell responses to tumor antigen stimulation revealed by Ptpn21 knock-out mouse model Restricted; Files Only
Chen, Angela (Spring 2026)
Abstract
Cytotoxic CD8⁺ T cells play a key role in anti-tumor immunity; however, the contribution of intrinsic biomechanical properties to their activation and function remains incompletely defined. While T cell activation is classically described as a biochemical process, increasing evidence suggests that cytoskeletal organization and mechanical cues also influence signaling outcomes. In this study, Ptpn21 knock-out (KO) mice were used as a model to examine how perturbation of cytoskeletal regulation affects CD8⁺ T cell mechanobiology and function.
Atomic force microscopy measurements showed that activated Ptpn21 KO CD8⁺ T cells are mechanically softer and more deformable than wild-type (WT) cells. Consistent with this, KO cells exhibited enhanced migration through confined environments. Under αCD3/CD28 stimulation, KO CD8⁺ T cells displayed reduced early activation, as indicated by lower CD25 and CD69 expression, together with decreased proliferative capacity and increased apoptosis. Immunofluorescence analysis further revealed disrupted F-actin organization in activated KO cells, suggesting altered cytoskeletal remodeling.
Despite showing increased calcium influx during store-operated calcium entry, KO CD8⁺ T cells did not exhibit enhanced activation or expansion. This observation suggests a potential uncoupling between calcium signaling and downstream functional responses, possibly due to altered spatial or temporal regulation of signaling. In vivo adoptive transfer experiments further demonstrated reduced persistence and accumulation of KO CD8⁺ T cells in lymphoid tissues and tumors. When challenged with tumor, while tumor growth was not significantly different between groups, a reduced frequency of CD8⁺ T cells was observed within the tumor microenvironment in KO mice.
In conclusion, these findings suggest that Ptpn21 contributes to the regulation of CD8⁺ T cell biomechanical properties, and that disruption of cytoskeletal organization may impair the coordination between signaling and functional output. This work supports a role for biomechanical regulation as an additional layer influencing T cell responses and may provide insight into factors that limit T cell effectiveness in tumor settings.
Table of Contents
INTRODUCTION ----- 4
RESULTS ----- 8
PTPN21 KO CD8+ T CELLS ARE BIOMECHANICALLY SOFTER, WITH A GREATER DEFORMABILITY, COMPARED TO WT CD8+ T CELLS ----- 8
PTPN21 KO CD8+ T CELLS HAVE WEAKER RESPONSE TO ΑCD3/CD28 DYNABEADS STIMULATION, SHOWING DECREASED ACTIVATION, AND ALTERED MEMORY FORMATION ----- 10
PTPN21 KO CD8+ T CELLS HAVE DYSREGULATED F-ACTIN CYTOSKELETAL ORGANIZATION, RESULTING IN DIMINISHED ACTIVATION-INDUCED CELLULAR STIFFNESS AND SUBSEQUENT DYSREGULATION OF CALCIUM INFLUX ----- 14
IN VIVO COMPETITIVE ADOPTIVE TRANSFER REVEALS THAT PTPN21 KO CD8+ T CELLS HAVE A LOSS OF CIRCULATION IN PERIPHERAL LYMPHATIC SYSTEM IN A TUMOR CHALLENGING ENVIRONMENT ----- 17
IN CIRCULATING DONOR CD8+ T CELLS, THOSE FROM PTPN21 KO ARE LESS ACTIVATED AND LESS PROLIFERATIVE ----- 20
PTPN21 KNOCK-OUT DOES NOT SIGNIFICANTLY ALTER TUMOR GROWTH BUT IS ASSOCIATED WITH REDUCED CD8⁺ T CELL REPRESENTATION IN TUMOR-INFILTRATING LYMPHOCYTES ----- 24
DISCUSSIONS AND FUTURE DIRECTION ----- 27
SUPPLEMENTARY FIGURES ----- 32
METHODOLOGY ----- 33
ACCOMPLISHMENT ----- 38
REFERENCE ----- 39
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File download under embargo until 27 May 2027 | 2026-04-20 14:07:55 -0400 | File download under embargo until 27 May 2027 |
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