Graft-versus-host disease propagation depends on increased intestinal epithelial tight junction permeability
Sam C. Nalle, … , Peter A. Savage, Jerrold R. Turner
Sam C. Nalle, … , Peter A. Savage, Jerrold R. Turner
Published January 22, 2019
Citation Information: J Clin Invest. 2019;129(2):902-914. https://doi.org/10.1172/JCI98554.
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Research Article Gastroenterology Oncology

Graft-versus-host disease propagation depends on increased intestinal epithelial tight junction permeability

Abstract

Graft-versus-host disease (GVHD) is a complication of hematopoietic stem cell transplantation (HSCT) that affects multiple organs. GVHD-associated intestinal damage can be separated into two distinct phases, initiation and propagation, which correspond to conditioning-induced damage and effector T cell activation and infiltration, respectively. Substantial evidence indicates that intestinal damage induced by pretransplant conditioning is a key driver of GVHD initiation. Here, we aimed to determine the impact of dysregulated intestinal permeability on the subsequent GVHD propagation phase. The initiation phase of GVHD was unchanged in mice lacking long MLCK (MLCK210), an established regulator of epithelial tight junction permeability. However, MLCK210-deficient mice were protected from sustained barrier loss and exhibited limited GVHD propagation, as indicated by reduced histopathology, fewer CD8+ effector T cells in the gut, and improved overall survival. Consistent with these findings, intestinal epithelial MLCK210 expression and enzymatic activity were similarly increased in human and mouse GVHD biopsies. Intestinal epithelial barrier loss mediated by MLCK210 is therefore a key driver of the GVHD propagation. These data suggest that inhibition of MLCK210-dependent barrier regulation may be an effective approach to limiting GVHD progression.

Authors

Sam C. Nalle, Li Zuo, Ma. Lora Drizella M. Ong, Gurminder Singh, Alicia M. Worthylake, Wangsun Choi, Mario Cabrero Manresa, Anna P. Southworth, Karen L. Edelblum, Gregory J. Baker, Nora E. Joseph, Peter A. Savage, Jerrold R. Turner

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Figure 6

GVHD is diminished in MLCK–/– mice following major mismatch BMT.

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GVHD is diminished in MLCK–/– mice following major mismatch BMT. B6 WT o...
B6 WT or MLCK–/– recipients were lethally irradiated, followed by BALB/c BMT. (A) Gross photos of 3 mice/group 35 days after BMT. Arrowhead points to hair loss and skin ulcers. Scale bar: 0.5 cm. (B) Representative histopathology of jejunum (arrowheads denote apoptotic epithelial cells; arrows indicate intraepithelial lymphocytes), liver (arrowhead indicates intraepithelial lymphocyte; asterisk denotes neutrophils, i.e., active pericholangitis), and skin (asterisk is adjacent to a damaged pilosebaceous gland) on d35. Scale bars: intestine, 200 μm, 20 μm; liver, 200 μm, 20 μm; skin, 100 μm. (C) Total pathology scores (jejunum, liver, and skin) 35 days after BMT. Each point represents an individual mouse. **P < 0.01, 2-tailed t test. (D) Disease activity scores at 35 days after BMT. Each point represents an individual mouse. *P < 0.01, 2-tailed t test. (E) Survival (n = 9 per group). *P < 0.05, Kaplan-Meier log-rank test, MLCK–/– compared with WT. (F) MLCK210 mRNA was analyzed by qPCR in purified jejunal epithelial cells. Each point represents an individual mouse. Data are normalized to the mean of mice that did not receive BMT. **P < 0.01, 2-tailed t test. (G and H) Jejunum was harvested 35 days after BMT and sections immunostained for phosphorylated myosin light chain (pMLC, green) and E-cadherin (ECAD, red). Arrowheads denote perijunctional actomyosin ring. **P < 0.01, 2-tailed t test. Scale bar: 25 μm. (I) Jejunum was harvested 35 days after BMT and immunostained for CD8, granzyme B, and E-cadherin. Left: quantification of CD8+granzyme B+ cells/mm2 of tissue. **P < 0.01, 2-tailed t test. Right: representative images of CD8 (green) infiltration. Arrowheads in low-power views denote intraepithelial CD8+ cells. Scale bars: 50 μm, 10 μm.