Basic Study
Copyright ©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 28, 2023; 29(24): 3793-3806
Published online Jun 28, 2023. doi: 10.3748/wjg.v29.i24.3793
Transcriptome sequencing and experiments reveal the effect of formyl peptide receptor 2 on liver homeostasis
Hui Liu, Ze-Yu Sun, Hua Jiang, Xu-Dong Li, Yong-Qiang Jiang, Peng Liu, Wen-Hua Huang, Qing-Yu Lv, Xiang-Lilan Zhang, Rong-Kuan Li
Hui Liu, Department of Gastroenterology, Second Hospital of Dalian Medical University, Dalian 116000, Liaoning Province, China
Ze-Yu Sun, Hua Jiang, Yong-Qiang Jiang, Peng Liu, Wen-Hua Huang, Qing-Yu Lv, Xiang-Lilan Zhang, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, China
Xu-Dong Li, Microbiology Teaching and Research Office, Anhui Medical University, Hefei 230032, Anhui Province, China
Rong-Kuan Li, Department of Infectious Diseases, Second Hospital of Dalian Medical University, Dalian 116000, Liaoning Province, China
Author contributions: Li RK designed the research; Liu H wrote the manuscript; Jiang H, Sun ZY, and Li XD conducted experiments; Liu P, Huang WH, and Lv QY analyzed the data and drew pictures; Jiang YQ and Zhang XL revised the manuscript content; all authors approved the final version of the article.
Supported by the State Key Laboratory of Pathogen and Biosecurity, No. SKLPBS2119 and SKLPBS2212; and the Medical Science Research Project of Dalian, No. 2112015.
Institutional animal care and use committee statement: The animal study was reviewed and approved by the animal center of the Academy of Military Medical Sciences. The protocol for animal handling and experiment was approved by the Institutional Review Board of Academy of Military Medical Science (No: IACUC-DWZX-2022-052).
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
Data sharing statement: The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found below: https://www.ncbi.nlm.nih.gov/, PRJNA923726.
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Rong-Kuan Li, MD, Chief Doctor, Department of Infectious Diseases, Second Hospital of Dalian Medical University, No. 467 Zhongshan Road, Shahekou District, Dalian 116000, Liaoning Province, China. dalianlrk1@163.com
Received: April 18, 2023
Peer-review started: April 18, 2023
First decision: April 26, 2023
Revised: May 4, 2023
Accepted: May 22, 2023
Article in press: May 22, 2023
Published online: June 28, 2023
Processing time: 71 Days and 1 Hours
Abstract
BACKGROUND

Formyl peptide receptor 2 (Fpr2) is an important receptor in host resistance to bacterial infections. In previous studies, we found that the liver of Fpr2-/- mice is the most severely damaged target organ in bloodstream infections, although the reason for this is unclear.

AIM

To investigate the role of Fpr2 in liver homeostasis and host resistance to bacterial infections.

METHODS

Transcriptome sequencing was performed on the livers of Fpr2-/- and wild-type (WT) mice. Differentially expressed genes (DEGs) were identified in the Fpr2-/- and WT mice, and the biological functions of DEGs were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) en-richment analysis. Quantitative real time-polymerase chain reaction (qRT-PCR) and western blot (WB) analyses were used to further validate the expression levels of differential genes. Cell counting kit-8 assay was employed to investigate cell survival. The cell cycle detection kit was used to measure the distribution of cell cycles. The Luminex assay was used to analyze cytokine levels in the liver. The serum biochemical indices and the number of neutrophils in the liver were measured, and hepatic histopathological analysis was performed.

RESULTS

Compared with the WT group, 445 DEGs, including 325 upregulated genes and 120 downregulated genes, were identified in the liver of Fpr2-/- mice. The enrichment analysis using GO and KEGG showed that these DEGs were mainly related to cell cycle. The qRT-PCR analysis confirmed that several key genes (CycA, CycB1, Cdc20, Cdc25c, and Cdk1) involved in the cell cycle had significant changes. The WB analysis confirmed a decrease in the expression of CDK1 protein. WRW4 (an antagonist of Fpr2) could inhibit the proliferation of HepG2 cells in a concentration dependent manner, with an increase in the number of cells in the G0/G1 phase, and a decrease in the number of cells in the S phase. Serum alanine aminotransferase levels increased in Fpr2-/- mice. The Luminex assay measurements showed that interleukin (IL)-10 and chemokine (C-X-C motif) ligand (CXCL)-1 levels were significantly reduced in the liver of Fpr2-/- mice. There was no difference in the number of neutrophils, serum C-reactive protein levels, and liver pathology between WT and Fpr2-/- mice.

CONCLUSION

Fpr2 participates in the regulation of cell cycle and cell proliferation, and affects the expression of IL-10 and CXCL-1, thus playing an important protective role in maintaining liver homeostasis.

Keywords: Cell cycle; Cell proliferation; Cdk1; Differentially expressed genes; Formyl peptide receptor 2; RNA-sequencing

Core Tip: Formyl peptide receptor 2 (Fpr2) is an important receptor in host resistance to bacterial infection. After Fpr2 deletion, the pathways involved in the cell cycle are affected, the expression of Cdk1 is downregulated, the proliferation activity of HepG2 cells is reduced, and the distribution of cell cycle is abnormal. After Fpr2 deletion, the permeability of the hepatocyte membrane increases, and the expression of interleukin-10 and Chemokine (C-X-C motif) ligand-1 decreases. These changes reflect the important protective effect of Fpr2 in maintaining liver homeostasis.