Chemotaxis overrides the killing response in alloreactive CTLs, providing vascular immune privilege during cellular rejection
Thomas Barba, Martin Oberbarnscheidt, Gregory Franck, Chantal Gao, Sebastien This, Maud Rabeyrin, Candice Roufosse, Linda Moran, Alice Koenig, Virginie Mathias, Carole Saison, Valérie Dubois, Nicolas Pallet, Dany Anglicheau, Baptiste Lamarthée, Alexandre Hertig, Emmanuel Morelon, Arnaud Hot, Helena Paidassi, Thierry Defrance, Antonio Nicoletti, Jean-Paul Duong Van Huyen, Yi-Chung Xu-Dubois, Faddi G. Lakkis, Olivier Thaunat
Thomas Barba, Martin Oberbarnscheidt, Gregory Franck, Chantal Gao, Sebastien This, Maud Rabeyrin, Candice Roufosse, Linda Moran, Alice Koenig, Virginie Mathias, Carole Saison, Valérie Dubois, Nicolas Pallet, Dany Anglicheau, Baptiste Lamarthée, Alexandre Hertig, Emmanuel Morelon, Arnaud Hot, Helena Paidassi, Thierry Defrance, Antonio Nicoletti, Jean-Paul Duong Van Huyen, Yi-Chung Xu-Dubois, Faddi G. Lakkis, Olivier Thaunat
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Research Article Immunology Nephrology

Chemotaxis overrides the killing response in alloreactive CTLs, providing vascular immune privilege during cellular rejection

Abstract

Graft endothelial cells (ECs) express donor alloantigens and encounter cytotoxic T lymphocytes (CTLs) but are generally spared during T cell–mediated rejection (TCMR), which predominantly affects epithelial structures. The mechanisms underlying this vascular immune privilege are unclear. Transcriptomics analyses and endothelial-mesenchymal transition assessments confirmed that the graft endothelium was preserved during TCMR. Coculture experiments revealed that endothelial and epithelial cells were equally susceptible to CTL-mediated lysis, ruling out cell-intrinsic protection. Intravital microscopy of murine kidney grafts and single-cell RNA-Seq of human renal allografts demonstrated that CTL interactions with ECs were transient compared with epithelial cells. This disparity was mediated by a chemotactic gradient produced by graft stromal cells, guiding CTLs away from ECs toward epithelial targets. In vitro, chemotaxis overrode T cell receptor–induced cytotoxicity, preventing endothelial damage. Finally, analysis of TCMR biopsies revealed that disruption of the chemotactic gradient correlated with endothelialitis lesions, linking its loss to vascular damage. These findings challenge the traditional view of cell-intrinsic immune privilege, proposing a cell-extrinsic mechanism, in which chemotaxis preserves graft vasculature during TCMR. This mechanism may have implications beyond transplantation, highlighting its role in maintaining vascular integrity across pathological conditions.

Authors

Thomas Barba, Martin Oberbarnscheidt, Gregory Franck, Chantal Gao, Sebastien This, Maud Rabeyrin, Candice Roufosse, Linda Moran, Alice Koenig, Virginie Mathias, Carole Saison, Valérie Dubois, Nicolas Pallet, Dany Anglicheau, Baptiste Lamarthée, Alexandre Hertig, Emmanuel Morelon, Arnaud Hot, Helena Paidassi, Thierry Defrance, Antonio Nicoletti, Jean-Paul Duong Van Huyen, Yi-Chung Xu-Dubois, Faddi G. Lakkis, Olivier Thaunat

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Figure 3

Distinct contact durations of alloreactive CTLs with endothelial and tubular epithelial cell targets.

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Distinct contact durations of alloreactive CTLs with endothelial and tub...
(A) Schematic representation of the murine model of TCMR of renal allografts. (B and C) Representative findings of intravital microscopy analysis of OVA-specific OT-I (yellow) or control P14 (cyan) CTLs trafficking within B6-OVA renal allografts. The vascular compartment is identified by fluorescent dextran (red). (B) Global view. The tracks of the cells were color-coded according to their position: intravascular (red) or extravascular (blue). Scale bars: 50 μm. (C) Representative behavior of OT-I (left columns) and P14 (right columns) cells in the intravascular (upper rows) and extravascular (lower rows) compartments (scale bars: 10 μm; time stamps format = mm:ss). (D–F) Comparison of the trafficking behavior of OT-I and P14 cells in intravascular (red) and extravascular (blue) compartments of the graft. Results in D and E represent independent experiments. (D) OVA-specific OT-I and control P14 CTLs were cotransferred into a mouse that had received a B6-OVA renal allograft (n = 1). Each symbol corresponds to a tracked cell. (E) OVA-specific OT-I CTLs were transferred alone into mice that had received a B6-OVA renal allograft (n = 2 experiments involving 2 animals each; each shape represents an individual animal). Individual cells are represented by a small symbol, and the larger symbol is the mean for the animal. Data represent the mean ± SEM. **P < 0.01 and ***P < 0.001, by 2-sided Student’s t test. (F) Overlay of individual OT-I T cell tracks plotted after aligning their starting positions. Cells were tracked over a 30-minute period in the intravascular (red) or extra vascular (blue) compartments. (G and H) Quantification of infiltrating CTLs in vascular and tubular epithelial compartments of 5 renal allograft biopsies with TCMR. (G) Computer-assisted quantification of CTLs (CD8+, brown) in the tubular epithelial (COL-IV, red, left column) and vascular (CD34+, red, right column) compartments of rejected renal allografts. CTLs were automatically counted within (green circles) and outside (black circles) each compartment (scale bars: 50 μm). (H) The density of CTLs in intravascular (red) and tubular epithelial (extravascular, blue) compartments was compared. E/T, effector/target ratio. ***P < 0.001, by Wilcoxon signed-rank test.