Lymph node fibroblastic reticular cells deposit fibrosis-associated collagen following organ transplantation
Xiaofei Li, … , Jonathan S. Bromberg, Reza Abdi
Xiaofei Li, … , Jonathan S. Bromberg, Reza Abdi
Published June 29, 2020
Citation Information: J Clin Invest. 2020;130(8):4182-4194. https://doi.org/10.1172/JCI136618.
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Research Article Immunology

Lymph node fibroblastic reticular cells deposit fibrosis-associated collagen following organ transplantation

Abstract

Although the immune response within draining lymph nodes (DLNs) has been studied for decades, how their stromal compartment contributes to this process remains to be fully explored. Here, we show that donor mast cells were prominent activators of collagen I deposition by fibroblastic reticular cells (FRCs) in DLNs shortly following transplantation. Serial analysis of the DLN indicated that the LN stroma did not return to its baseline microarchitecture following organ rejection and that the DLN contained significant fibrosis following repetitive organ transplants. Using several FRC conditional-knockout mice, we show that induction of senescence in the FRCs of the DLN resulted in massive production of collagen I and a proinflammatory milieu within the DLN. Stimulation of herpes virus entry mediator (HVEM) on FRCs by its ligand LIGHT contributed chiefly to the induction of senescence in FRCs and overproduction of collagen I. Systemic administration of ex vivo–expanded FRCs to mice decreased DLN fibrosis and strengthened the effect of anti-CD40L in prolonging heart allograft survival. These data demonstrate that the transformation of FRCs into proinflammatory myofibroblasts is critically important for the maintenance of a proinflammatory milieu within a fibrotic DLN.

Authors

Xiaofei Li, Jing Zhao, Vivek Kasinath, Mayuko Uehara, Liwei Jiang, Naima Banouni, Martina M. McGrath, Takaharu Ichimura, Paolo Fiorina, Dario R. Lemos, Su Ryon Shin, Carl F. Ware, Jonathan S. Bromberg, Reza Abdi

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Figure 1

Mast cells as early inducers of collagen I deposition in the DLN.

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Mast cells as early inducers of collagen I deposition in the DLN. (A) Im...
(A) Images show a comparison of collagen I (red) expression between the DLNs of mice on day 1 after allogeneic skin transplantation and the LNs of naive mice. Scale bars: 50 μm. Semiquantitative assessment is shown in the graph. n = 4. (B) Toluidine blue staining of mast cells (dashed circles) and comparison of their populations in DLNs and naive LNs. Scale bars: 50 μm. n = 4. (C) Representative IF staining of mast cells and semiquantitative assessment of FcεRI (green) expression by mast cells in DLNs. Lyve-1+ lymphatic endothelium (red) and DAPI+ nuclei (blue) staining is also shown. Scale bars: 50 μm. n = 4. (D) IF staining of collagen I (red) and Lyve-1 (green) in the LNs of naive BALB/c mice, as well as the DLNs of C57BL/6→BALB/c skin-transplanted mice and KitW-sh/W-sh→BALB/c skin-transplanted mice. Scale bars: 50 μm. n = 4. (E) Gene expression levels of the mast cell proteases as well as Vegfa, Fgf2, and Il6 with and without H2O2 stimulation (n = 4; each dot represents 1 sample). (F) Gene expression levels of Col1a1, Tgfb1, and Smad2 in FRCs following treatment with different mast cell–conditioned media (CM). n = 4. (G) Micrographs and tube formation analysis of SVEC4-10 cells treated with different mast cell–conditioned media. Scale bars: 100 μm. The percentage of the areas stained positive in the fluorescence micrographs was assessed in 3–6 random microscopic fields for each mouse. Data are presented as the mean ± SD. *P < 0.05 and **P < 0.01, by 2-tailed Student’s t test (A–C, and E) and 2-way ANOVA with Tukey’s multiple comparisons post hoc test (F and G).