Lymph node fibroblastic reticular cells preserve a tolerogenic niche in allograft transplantation through laminin α4
Lushen Li, … , Reza Abdi, Jonathan S. Bromberg
Lushen Li, … , Reza Abdi, Jonathan S. Bromberg
Published July 1, 2022
Citation Information: J Clin Invest. 2022;132(13):e156994. https://doi.org/10.1172/JCI156994.
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Research Article Cell biology

Lymph node fibroblastic reticular cells preserve a tolerogenic niche in allograft transplantation through laminin α4

Abstract

Lymph node (LN) fibroblastic reticular cells (FRCs) define LN niches and regulate lymphocyte homeostasis through producing diverse extracellular matrix (ECM) components. We examined the role of ECM laminin α4 (Lama4) using FRC-Lama4 conditional KO Pdgfrb-Cre–/– × Lama4fl/fl mice. Single-cell RNA-sequencing (scRNA-Seq) data showed the promoter gene Pdgfrb was exclusively expressed in FRCs. Depleting FRC-Lama4 reduced Tregs and dendritic cells, decreased high endothelial venules, impaired the conduit system, and downregulated T cell survival factors in LNs. FRC-Lama4 depletion impaired the homing of lymphocytes to LNs in homeostasis and after allografting. Alloantigen-specific T cells proliferated, were activated to greater degrees in LNs lacking FRC-Lama4, and were more prone to differentiate into effector phenotypes relative to the Treg phenotype. In murine cardiac transplantation, tolerogenic immunosuppression was not effective in FRC-Lama4 recipients, which produced more alloantibodies than WT. After lung transplantation, FRC-Lama4–KO mice had more severe graft rejection with fewer Tregs in their LNs. Overall, FRC-Lama4 critically contributes to a tolerogenic LN niche by supporting T cell migration, constraining T cell activation and proliferation, and promoting Treg differentiation. Hence, it serves as a therapeutic target for immunoengineering.

Authors

Lushen Li, Marina W. Shirkey, Tianshu Zhang, Wenji Piao, Xiaofei Li, Jing Zhao, Zhongcheng Mei, Yizhan Guo, Vikas Saxena, Allison Kensiski, Samuel J. Gavzy, Yang Song, Bing Ma, Jing Wu, Yanbao Xiong, Long Wu, Xiaoxuan Fan, Holly Roussey, Meng Li, Alexæander S. Krupnick, Reza Abdi, Jonathan S. Bromberg

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Figure 1

FRCs support LN structure and cellularity.

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FRCs support LN structure and cellularity. To deplete FRCs, CCL19/iDTR m...
To deplete FRCs, CCL19/iDTR mice were treated with DT (i.p. 100 ng/d × 5 days). (A and B) Whole-mount scanning (A) and fluorescent images (B) of LN cryosections stained for ER-TR7, Pdpn, PNAd, and Lyve-1. Original magnification, ×20. Scale bars: 500 μm (A); 100 μm (B). Quantification of PNAd intensity in HEV areas and Pdpn intensity in CR. (C) Whole-mount scanning of LN cryosections stained for Foxp3, CD3, B220, CD4, CD8, and ER-TR7. Original magnification, ×20. Scale bars: 500 μm. Quantification of CD3, Foxp3, CD4, and CD8 intensity, and Foxp3/CD3 ratio in CR. (D) Representative fluorescent images of LN cryosections stained for CXCL12, CCL21, and ER-TR7. Scale bars: 100 μm. Quantification of intensity in CR and around HEVs. (E) Whole-mount scanning of LN cryosections stained for IL-33 and ER-TR7. Scale bar: 500 μm. Quantification of intensity in T-zone. (A–E) Three independent experiments, 3 mice/group, 3 LNs/mouse, 3 sections/LN, 3 to 5 fields/section. Student’s unpaired, 2-tailed t test for 2-group comparisons. Data are represented as mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. P < 0.05 was considered significant.