Neutrophil-induced genomic instability impedes resolution of inflammation and wound healing
Veronika Butin-Israeli, … , Stephen B. Hanauer, Ronen Sumagin
Veronika Butin-Israeli, … , Stephen B. Hanauer, Ronen Sumagin
Published January 14, 2019
Citation Information: J Clin Invest. 2019;129(2):712-726. https://doi.org/10.1172/JCI122085.
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Research Article Gastroenterology Inflammation

Neutrophil-induced genomic instability impedes resolution of inflammation and wound healing

Abstract

Neutrophil (PMN) infiltration of the intestinal mucosa is a hallmark of tissue injury associated with inflammatory bowel diseases (IBDs). The pathological effects of PMNs are largely attributed to the release of soluble mediators and reactive oxygen species (ROS). We identified what we believe is a new, ROS-independent mechanism whereby activated tissue-infiltrating PMNs release microparticles armed with proinflammatory microRNAs (miR-23a and miR-155). Using IBD clinical samples, and in vitro and in vivo injury models, we show that PMN-derived miR-23a and miR-155 promote accumulation of double-strand breaks (DSBs) by inducing lamin B1–dependent replication fork collapse and inhibition of homologous recombination (HR) by targeting HR-regulator RAD51. DSB accumulation in injured epithelium led to impaired colonic healing and genomic instability. Targeted inhibition of miR-23a and miR-155 in cultured intestinal epithelial cells and in acutely injured mucosa decreased the detrimental effects of PMNs and enhanced tissue healing responses, suggesting that this approach can be used in therapies aimed at resolution of inflammation, in wound healing, and potentially to prevent neoplasia.

Authors

Veronika Butin-Israeli, Triet M. Bui, Hannah L. Wiesolek, Lorraine Mascarenhas, Joseph J. Lee, Lindsey C. Mehl, Kaitlyn R. Knutson, Stephen A. Adam, Robert D. Goldman, Arthur Beyder, Lisa Wiesmuller, Stephen B. Hanauer, Ronen Sumagin

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Figure 3

PMN-MPs inhibit DSB repair by homologous recombination.

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PMN-MPs inhibit DSB repair by homologous recombination. IECs were cocult...
IECs were cocultured with PMN-MPs. (A and B) At the indicated time points IECs were stained for 53BP1 (red) and γH2AX (green), and DSB foci were visualized by confocal microscopy. (A) Kinetics of DSB repair in PMN-MP– or CMPT-treated IECs was quantified from images as shown in (B), for which more than 600 nuclei per time point for each condition were quantified (n = 4, ***P < 0.001). (C) Analysis of IECs for EGFP fluorescence, induced by activation of HR or NHEJ (HCT116 cell line, n = 4; CaCo2 cell line, n = 3; **P < 0.01). (D) Immunoblotting and (E) gene expression analysis of LB1 and RAD51 in PMN-MP treated IECs (n = 5, *P < 0.05). (F) MPs were isolated from PMNs that were stimulated with fMLF (1 μM), TNF-α (10 nM), or IFN-γ (50 nM), and the relative expression of miR-23a, miR-155, and miR-103 was analyzed. Data are shown as fold increase over PMN-MPs that were isolated from unstimulated PMNs. U-6 was used as a reference gene (n = 6, *P < 0.05). One-way ANOVA was used for statistical analyses (P values). Data are mean ± SD from at least 3 independent experiments.