CD4+ T Cell Interstitial Migration Controlled by Fibronectin in the Inflamed Skin

Abstract

The extracellular matrix (ECM) is extensively remodeled during inflammation providing essential guidance cues for immune cell migration and signals for cell activation and survival. There is increasing interest in the therapeutic targeting of ECM to mitigate chronic inflammatory diseases and enhance access to the tumor microenvironment. T cells utilize the ECM as a scaffold for interstitial migration, dependent on T cell expression of matrix-binding integrins α V β 1 /α V β 3 and tissue display of the respective RGD-containing ligands. The specific ECM components that control T cell migration are unclear. Fibronectin (FN), a canonical RGD-containing matrix component, is heavily upregulated in inflamed tissues and in vitro can serve as a substrate for leukocyte migration. However, limited by lack of tools to intravitally visualize and manipulate FN, the specific role of FN in effector T cell migration in vivo is unknown. Here, we utilize fluorescently-tagged FN to probe for FN deposition, and intravital multiphoton microscopy to visualize T cell migration relative to FN in the inflamed ear dermis. Th1 cells were found to migrate along FN fibers, with T cells appearing to actively push or pull against flexible FN fibers. To determine the importance of T cell interactions with FN, we used a specific inhibitor of FN polymerization, pUR4. Intradermal delivery of pUR4 (but not the control peptide) to the inflamed skin resulted in a local reduction in FN deposition. We also saw a striking attenuation of Th1 effector T cell movement at the pUR4 injection site, suggesting FN plays a key role in T cell interstitial migration. In mechanistic studies, pUR4 incubation with FN in vitro resulted in enhanced tethering of T cells to FN matrix, limiting productive migration. In vivo , such tethering led to increased Th1 accumulation in the inflamed dermis. Enhanced Th1 accumulation exacerbated inflammation with increased Th1 activation and IFNγ cytokine production. Thus, our studies highlight the importance of ECM FN fibrils for T cell migration in inflamed tissues and suggest that manipulating local levels of ECM FN may prove beneficial in promoting T cell accumulation in tissues and enhancing local immunity to infection or cancer.

Stromal Protein-Mediated Immune Regulation in Digestive Cancers

“…Although modulation of immune cell recruitment and functions by laminins has been described in addition to their structural function [ 88 ], their immunomodulatory role in digestive cancers remains to be clarified. As mentioned above, T cells can be excluded from solid tumors [ 59 , 89 ] and must cross the basement membrane to enter tumor areas. Interestingly, different laminins have been associated with permissive (LAMA8, LAMA4) [ 90 , 91 ] or non-permissive (LAMA5) T cell migration signals [ 92 ].…”

Dynamic Regulation of the Molecular Mechanisms of Regulatory T Cell Migration in Inflamed Skin

“…Migration of effector CD4 + T cells in the inflamed dermis has been shown to be dependent on integrins that bind the RGD motif in fibronectin ( 14 , 32 ). Moreover, inflammation-induced changes in the structure of dermal collagen correlate with increased levels of fibronectin closely associated with collagen fibres in the skin ( 32 ). Therefore, we examined the role of RGD-binding integrins in Treg dermal interstitial migration 24 and 48 hours post CS initiation ( Figures 3A–H ).…”

“…This indicates that the extensive Treg migration at later stages in the CS response is independent of the α v integrin. It is important to note that concurrently, the biochemical and cellular composition of the skin is undergoing significant alteration, including reduced collagen density ( Figure 2 ), and increased fibronectin content along with extensive immune cell infiltration ( 14 , 32 ). These alterations introduce numerous additional adhesive ligands with the potential to support Treg migration.…”

A workflow for rapid unbiased quantification of fibrillar feature alignment in biological images

“…This approach builds upon previous work employed in (Aratyn-Schaus et al, 2011;Cetera et al, 2014;Fernandes et al, 2020) and adds features such as periodic decomposition to improve the accuracy of the FFT angle determination along with the ability to search for the optimal length scale for comparison. The current implementation is available at github.com/OakesLab/AF T − Alignment_by_F ourier_T ransf orm, both in MATLAB (Mathworks, v2018b) and Python languages.…”