Chemotaxis overrides the killing response in alloreactive CTLs, providing vascular immune privilege during cellular rejection
Thomas Barba, … , Faddi G. Lakkis, Olivier Thaunat
Thomas Barba, … , Faddi G. Lakkis, Olivier Thaunat
Published May 28, 2025
Citation Information: J Clin Invest. 2025;135(14):e155191. https://doi.org/10.1172/JCI155191.
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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 2

Alloreactive CTLs interact with allogeneic ECs in vivo and mediate their destruction in vitro.

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Alloreactive CTLs interact with allogeneic ECs in vivo and mediate their...
(A and B) Confocal microscopy analyses of renal allograft biopsies with TCMR. (A) The donor origin of graft cells was confirmed by the expression of donor-specific mismatched HLA A24 molecules (green) on CD31+ (red) ECs (glomerular and peritubular capillaries) as well as on E-cadherin+ (blue) tubular epithelial cells (scale bars: 20 μm). (B) Percentage of CD31+ peritubular capillary and glomerular ECs (upper row, red) and tubular epithelial cells (lower row, blue) expressing donor-specific HLA A24 molecules. Results are from the analysis of distinct fields of 4 independent biopsies (mean ± SEM). (C) IHC analyses of renal allograft biopsies with TCMR. CD8+ CTLs (brown) interacted with graft tubular epithelial cells (upper row) as well as the CD34+ ECs (red; lower row) of glomerular (left panels) and peritubular (right panels) capillaries (scale bars: 20 μm). (D) Electron micrographs of the interactions of CTLs with the various compartments of a renal allograft (middle panel). Magnification of the interactions of CTLs with, respectively, the EC (endoth cell) of a peritubular capillary (left panels) and a tubular epithelial cell (right panels) is shown (scale bars: 5 μm). (E–H) Quantification of allospecific, CTL-mediated killing of glomerular ECs (ciGENC, red) and PT epithelial cells (HK-2, blue). (E) Target cell destruction by nonspecific or allospecific CTLs was assessed using time-lapse microscopy. The decrease in live cell area (calcein, green) and acquisition of the apoptosis marker (annexin V, red) were quantified. Representative images from the end of cocultures are shown (scale bar: 50 μm). (F) Quantification of cell destruction from 2 independent time-lapse experiments (median ± IQR ). Significance was determined by unpaired, 2-sample Wilcoxon test. (G) Kinetics monitoring of ciGENC (red) and HK-2 (blue) target cell destruction by allospecific CTLs based on impedance reduction in culture wells. Impedance values were normalized to control conditions with nonspecific CTLs. (H) AUC of the impedance values for ciGENC and HK-2 cocultures at varying effector/target ratios. Results from 2 independent experiments are shown. Significance was determined by 1-way ANOVA.