REVIEW article
Front. Immunol.
Sec. Autoimmune and Autoinflammatory Disorders : Autoimmune Disorders
Expanding Horizons: Radiolabeled FAPI in Imaging of Autoimmune Diseases
Jiaoniu Duan 1
Jinfang Gao 1
Gailian Zhang 2
Liyun Zhang 1
1. Shanxi Bethune Hospital, Shanxi Medical University, Taiyuan, China
2. Fifth Hospital of Shanxi Medical University, Taiyuan, China
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Abstract
Fibroblast activation protein alpha (FAP) is a type II transmembrane protease that exhibits both dipeptidyl peptidase and endopeptidase activities. It is upregulated in activated fibroblasts, particularly in tumor stroma and in fibrotic processes associated with various benign conditions. Recent studies have revealed that FAP is also highly expressed in certain Autoimmune Diseases (AIDs) characterized by chronic inflammation and tissue remodeling. Small-molecule inhibitors targeting FAP (FAPI) positron emission tomography (PET) provides a direct imaging modality for assessing fibroblast activation in vivo. FAPI's application in oncology has attracted considerable attention in nuclear medicine. However, evidence supporting its efficacy in AIDs remains limited. This review systematically evaluates the diagnostic and phenotyping potential of FAPI PET in AIDs, expands its applications across a broader disease spectrum, highlights technical advantages, and delineates future research directions.
Summary
Keywords
aids, Autoimmune Diseases, FAP, FAPI, fibroblast activation protein
Received
27 January 2026
Accepted
17 February 2026
Copyright
© 2026 Duan, Gao, Zhang and Zhang. 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: Liyun Zhang
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