Integrin-Mediated Mechanosensing of Modeled Lymph Node Microenvironment Promotes T Cell Activation via Nuclear Deformation.

Upon tumor metastasis, lymph nodes (LNs) undergo mechanical stiffening, yet how this change influences T cell activation within the microenvironment remains incompletely understood. In particular, the dynamic mechanical forces during activation are transduced by cell-extracellular matrix (ECM) interactions, while cell-cell interactions persist. Here, we established a novel T cell culture platform using hydrogels with tunable stiffness and decoupled presentation of RGD peptide and anti-CD3 monoclonal antibody, separately mimicking ECM-T cell and T cell-antigen-presenting cell interactions. This platform closely mimics the LN microenvironment during T cell activation. By integrating experiments with mathematical modeling, we revealed that T cells sensed mechanical changes in the microenvironment requiring RGD/integrin ligation, while stiff matrix up-regulated F-actin aggregation instead of myosin contraction, deforming the nucleus and promoting yes-associated protein nucleus translocation, resulting in interleukin-2 expression and T cell activation. Our findings shed light on the mechanobiological mechanism underlying the potential benefits of immunotherapy in patients with LN metastases and provide an optimized mechanical platform for studying T cell activation and expansion in vitro.