Loss of H2R Signaling Disrupts Neutrophil Homeostasis and Promotes Inflammation-Associated Colonic Tumorigenesis in Mice

Authors

Zhongcheng Shi
Yuko Mori-Akiyama
Wa Du
Robert Fultz
Yanling Zhao
Wenly Ruan
Susan Venable
Melinda A Engevik
James Versalovic

Publication Date

1-1-2022

Journal

Cellular and Molecular Gastroenterology and Hepatology

DOI

10.1016/j.jcmgh.2021.11.003

PMID

34781022

PMCID

PMC8783126

PubMedCentral® Posted Date

11-13-2021

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

Animals, Carcinogenesis, Homeostasis, Inflammation, Intestinal Mucosa, Mice, Neutrophils, Histamine, Cimetidine, Inflammation, Colorectal Cancer

Abstract

BACKGROUND & AIMS: We previously showed that histamine suppressed inflammation-associated colonic tumorigenesis through histamine type 2 receptor (H2R) signaling in mice. This study aimed to precisely elucidate the downstream effects of H2R activation in innate immune cells.

METHODS: Analyses using online databases of single-cell RNA sequencing of intestinal epithelial cells in mice and RNA sequencing of mouse immune cells were performed to determine the relative abundances of 4 histamine receptors among different cell types. Mouse neutrophils, which expressed greater amounts of H2R, were collected from the peritoneum of wild-type and H2R-deficient mice, of which low-density and high-density neutrophils were extracted by centrifugation and were subjected to RNA sequencing. The effects of H2R activation on neutrophil differentiation and its functions in colitis and inflammation-associated colon tumors were investigated in a mouse model of dextran sulfate sodium-induced colitis.

RESULTS: Data analysis of RNA sequencing and quantitative reverse-transcription polymerase chain reaction showed that Hrh2 is highly expressed in neutrophils, but barely detectable in intestinal epithelial cells. In mice, the absence of H2R activation promoted infiltration of neutrophils into both sites of inflammation and colonic tumors. H2R-deficient high-density neutrophils yielded proinflammatory features via nuclear factor-κB and mitogen-activated protein kinase signaling pathways, and suppressed T-cell proliferation. On the other hand, low-density neutrophils, which totally lack H2R activation, showed an immature phenotype compared with wild-type low-density neutrophils, with enhanced MYC pathway signaling and reduced expression of the maturation marker Toll-like receptor 4.

CONCLUSIONS: Blocking H2R signaling enhanced proinflammatory responses of mature neutrophils and suppressed neutrophil maturation, leading to accelerated progression of inflammation-associated colonic tumorigenesis.