REVIEW article
Front. Immunol.
Sec. Cytokines and Soluble Mediators in Immunity
Unraveling Fibrinogen-like Protein 1's Role in Immune Regulation
Provisionally accepted
Fengjia Xi
Rongzeng Liu*- Department of Immunology, College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, China
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Fibrinogen-like protein 1 (FGL1) has been recently identified as an emerging novel checkpoint ligand of lymphocyte activation gene-3 (LAG-3) with important immunoregulatory functions. In addition to LAG-3, FGL1 also interacts with bone morphogenetic protein 6 (BMP6), activin receptor-like kinase 5 (ALK5) and other unidentified receptors to perform biological functions. Physiologically, FGL1 restrains intrahepatic immunity and preserves tolerance. Pathologically, FGL1 is frequently upregulated in various tumors and autoimmune diseases and is closely related to the occurrence and development of these diseases. Targeting FGL1 has shown preclinical efficacy in enhancing immunotherapy involving programmed death ligand 1 (PD-L1)/PD-1 checkpoint blockade, inhibiting liver metastasis and relieving autoimmunity without overt hepatotoxicity. In this review, we summarize recent advances in FGL1, focus on the immunoregulatory functions of FGL1, and evaluate its potential as a therapeutic target for immune-related diseases.
Keywords: autoimmune disease, fgl1, Immune Regulation, Therapeutic target, tumor
Received: 25 Nov 2025; Accepted: 02 Feb 2026.
Copyright: © 2026 Xi and Liu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Rongzeng Liu
Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.