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 4

LIGHT increases ECM accumulation in DLNs by binding to HVEM in FRCs following transplantation.

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LIGHT increases ECM accumulation in DLNs by binding to HVEM in FRCs foll...
(A) IF staining for HVEM (green) expression in PDPN+ FRCs (red) in vitro. Scale bar: 10 μm. (B) Flow cytometric analysis of HVEM expression by FRCs through gating on the CD45–CD31–PDPN+ cell population from LNs. (C) Staining and semiquantitative analysis of collagen I fibers (red) in DLNRep (staining was normalized to DAPI). Scale bars: 10 μm. n = 4. (D) Gene expression levels of senescence and fibrosis genes in FRCs from WT and HVEM-KO mice treated with LIGHT (25 ng/mL). n = 6. (E) Western blot and quantification of protein levels of fibronectin, α-SMA, p21, and p16 in cultured WT FRCs after treatment with LIGHT (25 ng/mL). (F) IF staining of cultured WT FRCs with collagen I (green) and PDPN (red) after LIGHT (25 ng/mL) treatment compared with no treatment. Scale bars: 10 μm. (G) Measurement of protein levels of fibronectin and p16 in cultured HVEM-KO FRCs after LIGHT stimulation. (H) IF staining for LIGHT expression in mast cells. Scale bar:10 μm. The percentage of 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 Student’s t test.