Intestinal epithelial BLT1 promotes mucosal repair
Shusaku Hayashi, Chithra K. Muraleedharan, Makito Oku, Sunil Tomar, Simon P. Hogan, Miguel Quiros, Charles A. Parkos, Asma Nusrat
Shusaku Hayashi, Chithra K. Muraleedharan, Makito Oku, Sunil Tomar, Simon P. Hogan, Miguel Quiros, Charles A. Parkos, Asma Nusrat
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Research Article Gastroenterology Inflammation

Intestinal epithelial BLT1 promotes mucosal repair

Abstract

Acute and chronic intestinal inflammation is associated with epithelial damage, resulting in mucosal wounds in the forms of erosions and ulcers in the intestinal tract. Intestinal epithelial cells (IECs) and immune cells in the wound milieu secrete cytokines and lipid mediators to influence repair. Leukotriene B4 (LTB4), a lipid chemokine, binds to its receptor BLT1 and promotes migration of immune cells to sites of active inflammation; however, a role for intestinal epithelial BLT1 during mucosal wound repair is not known. Here we report that BLT1 was expressed in IECs both in vitro and in vivo, where it functioned as a receptor not only for LTB4 but also for another ligand, resolvin E1. Intestinal epithelial BLT1 expression was increased when epithelial cells were exposed to an inflammatory microenvironment. Using human and murine primary colonic epithelial cells, we reveal that the LTB4/BLT1 pathway promoted epithelial migration and proliferation leading to accelerated epithelial wound repair. Furthermore, in vivo intestinal wound repair experiments in BLT1-deficient mice and bone marrow chimeras demonstrated an important contribution of epithelial BLT1 during colonic mucosal wound repair. Taken together, our findings show a potentially novel prorepair in IEC mechanism mediated by BLT1 signaling.

Authors

Shusaku Hayashi, Chithra K. Muraleedharan, Makito Oku, Sunil Tomar, Simon P. Hogan, Miguel Quiros, Charles A. Parkos, Asma Nusrat

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Figure 3

BLT1 regulates intestinal epithelial wound repair.

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BLT1 regulates intestinal epithelial wound repair. (A) Effect of LTB4 in...
(A) Effect of LTB4 in the scratch wound assay using SKCO-15 cells. The data are presented as the mean ± SEM. Statistical analysis was performed using 1-way ANOVA followed by post hoc Welch’s t test with Bonferroni’s correction. *P < 0.05; **P < 0.01. (B and C) Effect of LTB4 in the scratch wound assay using human primary colonic epithelial monolayers. (B) Representative phase-contrast images at 0 and 24 hours after wounding are shown. Scale bar is 100 μm. (C) Quantification of change over time in wound repair is shown. The data are presented as the mean ± SEM. Statistical analysis was performed using 2-way ANOVA followed by post hoc Welch’s t test with Bonferroni’s correction. **P < 0.01; ***P < 0.001; ****P < 0.0001, compared with vehicle. †P < 0.05; ††P < 0.01: †††P < 0.001; ††††P < 0.0001, compared with LTB4. (D and E) Effect of LTB4 in the scratch wound assay using primary epithelial monolayers. (D) Representative phase-contrast images at 0 and 24 hours after wounding are shown. Scale bar is 100 μm. (E) Quantification of change over time in wound repair is shown. The data are presented as the mean ± SEM. Statistical analysis was performed using 2-way ANOVA followed by post hoc Welch’s t test with Bonferroni’s correction. *P < 0.05; ****P < 0.0001, compared with WT (vehicle). ††P < 0.01; ††††P < 0.0001, compared with Ltb4r1–/– (vehicle). (F) qPCR analysis of the changes in the expression of LTB4R mRNA in the human 2D cultured colonoid stimulated with IFN-γ (10 ng/mL) and TNF-α (10 ng/mL). The data are presented as the mean ± SEM. Statistical analysis was performed using an unpaired (2-tailed) t test with Welch’s correction. *P < 0.05. NT, nontreated. (G) Effect of IFN-γ (100 ng/mL) and TNF-α (100 ng/mL) on the prorepair activity of low-dose LTB4 (1 nM) in the scratch wound assay using SKCO-15 cells. The data are presented as the mean ± SEM. Statistical analysis was performed using 1-way ANOVA followed by post hoc Welch’s t test with Bonferroni’s correction. **P < 0.01; ***P < 0.001; ****P < 0.0001.