Targeting fibroblast activation protein in rheumatoid arthritis: from molecular imaging to precision therapeutics

Rheumatoid arthritis (RA), a chronic inflammatory disorder characterized by synovitis and joint destruction, remains a global health challenge. Activated fibroblast-like synoviocytes (FLS), which play a crucial role in the progression of RA, demonstrate tumor-like invasiveness and secrete inflammato...

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Main Authors: Yupeng Huang, Yang Wu, Huan Liu, Yuehong Chen, Qibing Xie, Geng Yin
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-06-01
Series:Frontiers in Immunology
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Online Access:https://www.frontiersin.org/articles/10.3389/fimmu.2025.1616618/full
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author Yupeng Huang
Yang Wu
Huan Liu
Yuehong Chen
Qibing Xie
Geng Yin
author_facet Yupeng Huang
Yang Wu
Huan Liu
Yuehong Chen
Qibing Xie
Geng Yin
author_sort Yupeng Huang
collection DOAJ
description Rheumatoid arthritis (RA), a chronic inflammatory disorder characterized by synovitis and joint destruction, remains a global health challenge. Activated fibroblast-like synoviocytes (FLS), which play a crucial role in the progression of RA, demonstrate tumor-like invasiveness and secrete inflammatory mediators. Fibroblast activation protein (FAP), a type II transmembrane serine protease, has been extensively studied in oncology for decades and has yielded significant clinical benefits. FAP is highly expressed in tumor-associated fibroblasts and plays a pivotal role in tumor growth, dissemination, and immune escape. In cancer imaging, small-molecule FAP inhibitor (FAPI) PET/CT has demonstrated superior sensitivity for detecting primary tumors and metastases. Additionally, FAP-targeted radionuclide therapy has emerged as a promising strategy for delivering precise radiation to tumors, while sparing healthy tissues. Beyond oncology, research on FAP in non-malignant diseases is rapidly advancing. In RA, FAP is overexpressed in RA-FLS but scarce in normal tissues. Thus, FAPI PET/CT can accurately visualize synovitis and monitor the treatment response in patients with RA. Similarly, FAP imaging is used to assess extra-articular manifestations, such as interstitial lung disease and cardiac fibrosis, by mapping fibroblast activity, offering a non-invasive tool. Moreover, emerging therapies, such as FAP-targeted photodynamic therapy, selectively eliminate pathogenic cells in RA models, highlighting their therapeutic potential. This review highlights the advances in FAP-targeted imaging for RA, specifically focusing on FAP as a key biomarker for diagnosis, disease evaluation, and potential therapeutic use in RA.
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spelling doaj-art-d18da9ecda7e45ba972756334e316e632025-08-20T02:35:56ZengFrontiers Media S.A.Frontiers in Immunology1664-32242025-06-011610.3389/fimmu.2025.16166181616618Targeting fibroblast activation protein in rheumatoid arthritis: from molecular imaging to precision therapeuticsYupeng Huang0Yang Wu1Huan Liu2Yuehong Chen3Qibing Xie4Geng Yin5Department of General Practice, General Practice Medical Center, West China Hospital, Sichuan University, Chengdu, Sichuan, ChinaDepartment of General Practice, General Practice Medical Center, West China Hospital, Sichuan University, Chengdu, Sichuan, ChinaDepartment of Rheumatology and Immunology, West China Hospital, Sichuan University, Chengdu, Sichuan, ChinaDepartment of Rheumatology and Immunology, West China Hospital, Sichuan University, Chengdu, Sichuan, ChinaDepartment of Rheumatology and Immunology, West China Hospital, Sichuan University, Chengdu, Sichuan, ChinaDepartment of General Practice, General Practice Medical Center, West China Hospital, Sichuan University, Chengdu, Sichuan, ChinaRheumatoid arthritis (RA), a chronic inflammatory disorder characterized by synovitis and joint destruction, remains a global health challenge. Activated fibroblast-like synoviocytes (FLS), which play a crucial role in the progression of RA, demonstrate tumor-like invasiveness and secrete inflammatory mediators. Fibroblast activation protein (FAP), a type II transmembrane serine protease, has been extensively studied in oncology for decades and has yielded significant clinical benefits. FAP is highly expressed in tumor-associated fibroblasts and plays a pivotal role in tumor growth, dissemination, and immune escape. In cancer imaging, small-molecule FAP inhibitor (FAPI) PET/CT has demonstrated superior sensitivity for detecting primary tumors and metastases. Additionally, FAP-targeted radionuclide therapy has emerged as a promising strategy for delivering precise radiation to tumors, while sparing healthy tissues. Beyond oncology, research on FAP in non-malignant diseases is rapidly advancing. In RA, FAP is overexpressed in RA-FLS but scarce in normal tissues. Thus, FAPI PET/CT can accurately visualize synovitis and monitor the treatment response in patients with RA. Similarly, FAP imaging is used to assess extra-articular manifestations, such as interstitial lung disease and cardiac fibrosis, by mapping fibroblast activity, offering a non-invasive tool. Moreover, emerging therapies, such as FAP-targeted photodynamic therapy, selectively eliminate pathogenic cells in RA models, highlighting their therapeutic potential. This review highlights the advances in FAP-targeted imaging for RA, specifically focusing on FAP as a key biomarker for diagnosis, disease evaluation, and potential therapeutic use in RA.https://www.frontiersin.org/articles/10.3389/fimmu.2025.1616618/fullrheumatoid arthritisfibroblast activation proteinFAPIdisease evaluationtreatment
spellingShingle Yupeng Huang
Yang Wu
Huan Liu
Yuehong Chen
Qibing Xie
Geng Yin
Targeting fibroblast activation protein in rheumatoid arthritis: from molecular imaging to precision therapeutics
Frontiers in Immunology
rheumatoid arthritis
fibroblast activation protein
FAPI
disease evaluation
treatment
title Targeting fibroblast activation protein in rheumatoid arthritis: from molecular imaging to precision therapeutics
title_full Targeting fibroblast activation protein in rheumatoid arthritis: from molecular imaging to precision therapeutics
title_fullStr Targeting fibroblast activation protein in rheumatoid arthritis: from molecular imaging to precision therapeutics
title_full_unstemmed Targeting fibroblast activation protein in rheumatoid arthritis: from molecular imaging to precision therapeutics
title_short Targeting fibroblast activation protein in rheumatoid arthritis: from molecular imaging to precision therapeutics
title_sort targeting fibroblast activation protein in rheumatoid arthritis from molecular imaging to precision therapeutics
topic rheumatoid arthritis
fibroblast activation protein
FAPI
disease evaluation
treatment
url https://www.frontiersin.org/articles/10.3389/fimmu.2025.1616618/full
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