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 February 1, 2019; First 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 7

Genetic MLCK210 inhibition reduces effector CD8+ T cell accumulation within mesenteric, but not systemic, lymph nodes.

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Genetic MLCK210 inhibition reduces effector CD8+ T cell accumulation wit...
B6 mOVATg (n = 14), B6 mOVATgMLCK–/– (n = 11), and B6 WT controls (n = 4) were lethally irradiated, followed by an OT-I BMT consisting of 5 million WT bone marrow cells, 10 million WT splenocytes, and 2 million OT-I splenocytes. (A) Weight and (B) disease activity scores. **P < 0.01, 2-tailed t tests on d35. (C) Pathology scores of GVHD target organs (jejunum, liver, and skin) and representative small intestinal histopathology 35 days after BMT. Each point represents an individual mouse. *P < 0.05, 2-tailed t test. Arrows denote intraepithelial lymphocytes; arrowheads denote apoptotic bodies. Scale bars: 50 μm; inset: 10 μm. (D) Small intestine samples from day 35 after BMT were immunostained for CD3 (green), ZO-1 (red), E-cadherin (ECAD, blue), and Hoechst 33342 (white). Representative images are shown. Scale bar: 50μm. Graph shows CD3+ infiltration in the small intestine 35 days after BMT; each point represents an individual mouse. *P < 0.05, 2-tailed t test. (E) Flow cytometry analysis of cells isolated from spleen, mesenteric lymph nodes (MLN), and axillary/brachial lymph nodes (A/B) on d35 after BMT. The proportions of CD8+ T cells relative to live cells are shown. (F and G) CD8+ T cell intracellular granzyme B expression as evaluated by flow cytometry 35 days after BMT. (F) Representative flow cytometry plots and (G) quantification. Each point represents an individual sample. *P < 0.05, 2-tailed t test.