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Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Oncol. Dec 15, 2021; 13(12): 2013-2028
Published online Dec 15, 2021. doi: 10.4251/wjgo.v13.i12.2013
Macrophages play a role in inflammatory transformation of colorectal cancer
Lu Lu, Yu-Jing Liu, Pei-Qiu Cheng, Dan Hu, Han-Chen Xu, Guang Ji
Lu Lu, Yu-Jing Liu, Pei-Qiu Cheng, Han-Chen Xu, Guang Ji, Institute of Digestive Diseases, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, China
Dan Hu, Han-Chen Xu, Shanghai Pudong New Area Hospital of Traditional Chinese Medicine, Shanghai 200120, China
Author contributions: Lu L, Liu YJ, Cheng PQ, and Hu D wrote the manuscript; Ji G and Xu HC are co-corresponding authors, and they contributed to editing the manuscript; all authors wrote, read, and approved the final manuscript.
Supported by The National Nature Science Foundation of China, No. 81874206; Shanghai Rising-Star Program, No. 20QA1409300; and the Program for Young Eastern Scholar at Shanghai Institutions of Higher Learning, No. QD2019034.
Conflict-of-interest statement: There is no conflict of interest associated with any of the senior author or other coauthors who contributed their efforts in this manuscript.
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: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Guang Ji, MD, PhD, Chief Doctor, Professor, Institute of Digestive Diseases, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, No. 725 South Wanping Road, Shanghai 200032, China. jiliver@vip.sina.com
Received: May 17, 2021
Peer-review started: May 17, 2021
First decision: July 14, 2021
Revised: July 21, 2021
Accepted: August 25, 2021
Article in press: August 25, 2021
Published online: December 15, 2021
Processing time: 211 Days and 15.3 Hours
Abstract

Colorectal cancer (CRC) is one of the most common and fatal cancers worldwide, and it is also a typical inflammatory cancer. The function of macrophages is very important in the tissue immune microenvironment during inflammatory and carcinogenic transformation. Here, we evaluated the function and mechanism of macrophages in intestinal physiology and in different pathological stages. Furthermore, the role of macrophages in the immune microenvironment of CRC and the influence of the intestinal population and hypoxic environment on macrophage function are summarized. In addition, in the era of tumor immunotherapy, CRC currently has a limited response rate to immune checkpoint inhibitors, and we summarize potential therapeutic strategies for targeting tumor-associated macrophages.

Keywords: Colorectal cancer, Macrophages, Inflammatory transformation, Tumor microenvironment

Core Tip: In this review, we provide a comprehensive review of the research progress of macrophages in intestinal inflammation and colorectal cancer. It is of great significance to discuss the intestinal macrophages under steady-state and inflammatory conditions and tumor-associated macrophages in the immune microenvironment. With the research on macrophages in intestinal inflammation and tumor diseases, targeted macrophage therapy will benefit patients with intestinal inflammation or colorectal cancer.