Their findings could guide the development of therapies with fewer side effects compared with broad immunosuppressants

Sjögren’s disease is a widespread chronic autoimmune disorder that attacks the body’s own glands, yet its underlying disease mechanisms remain poorly understood. In a recent study, researchers from Japan discovered a self-reinforcing loop between different immune cells that sustains autoimmune responses in patients with Sjögren’s disease. Their findings pave the way for safer and more effective therapies.

Sjögren’s disease is a chronic autoimmune disorder that affects millions of people worldwide. In patients with this disease, the immune system attacks the body’s own exocrine glands, such as the salivary and lacrimal glands, causing persistent dry mouth and dry eyes. The disease can also progress to affect the skin, lungs, kidneys, and peripheral nerves. Despite its prevalence, no curative treatment exists yet; patients often rely on broad immunosuppressive drugs that dampen the entire immune system rather than addressing the underlying cause.

A hallmark of Sjögren’s disease is the presence of anti-Ro60 autoantibodies, which mistakenly target the body’s own Ro60 protein. While B cells, the immune cells that produce antibodies, have been extensively studied in Sjögren’s disease, far less is known about the role of CD4⁺ T cells, which coordinate immune responses and help activate other immune cells. Scientists suspect that these T cells cooperate with B cells to sustain autoimmune reactions, but identifying the molecules recognized by pathogenic T cells has remained difficult.

In a recent study, a team of researchers led by Assistant Professor Masaru Takeshita from the Division of Rheumatology at the Department of Internal Medicine of Keio University School of Medicine, Japan, tackled this knowledge gap. As reported in their latest paper, which will be made available online in Science Advances on June 3, 2026, they analyzed immune cells isolated from the salivary glands of patients with Sjögren’s disease and identified, for the first time, disease-associated CD4⁺ T cells that recognize the same Ro60 protein targeted by autoreactive B cells.

To investigate how these immune responses develop, the team combined single-cell RNA sequencing with T-cell receptor (TCR) analysis. T-cell receptors are molecules that allow each T cell to recognize a specific target. The researchers identified more than 200 TCRs from immune cells infiltrating diseased salivary glands and tested whether they reacted to fragments of the Ro60 protein presented by patient HLA molecules. Using engineered reporter cells and artificial antigen-presenting systems, the team identified 13 TCRs that specifically recognized Ro60-derived peptides.

Through further analysis, the researchers shed light on a previously unrecognized process. They found that many of the Ro60-reactive T cells belonged to specialized subsets of CD4⁺ T cells known to stimulate antibody-producing B cells. The researchers also demonstrated that anti-Ro60 antibodies produced by B cells can bind to Ro60 proteins released from damaged cells, forming immune complexes that are efficiently taken up by antigen-presenting cells. These cells then display Ro60-derived peptides to CD4⁺ T cells, activating them and promoting additional antibody production. “Simply put, this process forms a self-reinforcing loop, sustaining autoimmune responses and contributing to chronic disease,” explains Dr. Takeshita. Notably, the results were consistent across both Japanese and Caucasian patients, suggesting this mechanism is a general feature of anti-Ro60-positive Sjögren’s disease regardless of genetic background.

Overall, this study contributes to a deeper understanding of Sjögren’s disease and could lead to the development of better treatment strategies. “Currently, therapies for Sjögren’s disease suppress immune responses broadly, affecting both harmful and protective immune functions. If the pathogenic loop we identified can be interrupted, it may be possible to selectively suppress disease-causing autoimmune responses without impairing normal immune function,” remarks Dr. Takeshita. “Such approaches could potentially reduce the risk of infections and other complications associated with systemic immunosuppression.”

Going forward, researchers at Keio University aim to further explore these newfound mechanisms and translate their findings into effective therapies for Sjögren’s disease and other autoimmune disorders, with the ultimate goal of improving patients’ quality of life.

Reference
Takeshita, M., Inamo, J., Wakui, S. et al. Identification of a shared antigen linking CD4⁺ T and B cell pathology in Sjögren’s disease. Sci Adv (2026). https://doi.org/10.1126/sciadv.aeb2491

About Keio University Global Research Institute (KGRI), Japan
The Keio University Global Research Institute (KGRI), established in November 2016, serves as a university-wide platform connecting faculties and graduate schools. It promotes interdisciplinary and international collaborative research that transcends academic and geographic boundaries, while disseminating research outcomes both domestically and globally.
In 2024, Keio University launched the Program for Forming Japan’s Peak Research Universities (J-PEAKS), funded by the Japan Society for the Promotion of Science (JSPS), under the vision of becoming a “research university that forges the common sense of the future.” Through this initiative, KGRI is strengthening research infrastructure to enhance interdisciplinary collaboration, promoting the societal implementation of research, and fostering a research ecosystem that enables collaboration across the university and with leading institutions in Japan and abroad.
Website: https://www.kgri.keio.ac.jp/en/index.html

About Assistant Professor Masaru Takeshita from Keio University
Dr.Takeshita is a physician-scientist at the Division of Rheumatology, Department of Internal Medicine, Keio University School of Medicine. He specializes in rheumatology and systemic autoimmune diseases. His research is driven by the goal of moving beyond long-standing, systemic immunosuppressive therapies and toward more targeted approaches through a deeper understanding of disease mechanisms in immune-mediated disorders. In recent years, he has focused on analyzing patient-derived lesional tissues in diseases such as Sjögren’s disease and inflammatory myopathies. Through these studies, he has demonstrated that immune responses against disease-specific autoantigens actively occur at sites of inflammation in multiple autoimmune conditions. He is actively involved in collaborative research projects between the Division of Rheumatology at Keio University and industry partners, contributing to translational initiatives that integrate multi-omics approaches, including immunoprofiling and glycomics analyses. In parallel with his research activities, he supervises PhD students, supporting the development of the next generation of physician-scientists.
https://researchmap.jp/read00071135
https://keio-rheum.jp/

Funding information
This work was supported by the following funding sources: Research Support Project for Life Science and Drug Discovery, Basis for Supporting Innovative Drug Discovery and Life Science Research (BINDS) from AMED under Grant Number JP25ama121015; JSR Corporation as a JKiC Next-generation Project to Masaru Takeshita (MT); The Japan Society for the Promotion of Science (JSPS) KAKENHI, Grant Numbers JP20K17430 (MT) and JP22K08528 (MT); Keio University Academic Development Funds (MT); Keio Gijuku Fukuzawa Memorial Fund for the Advancement of Education and Research (MT); The Program for the Advancement of Next Generation Research Projects (MT); The Mochida Memorial Foundation for Medical and Pharmaceutical Research (MT); The Kowa Life Science Foundation, the Japan Rheumatism Foundation (MT); The Takeda Science Foundation (MT); A research grant from the Astellas Foundation for Research on Metabolic Disorders (MT); The SENSHIN Medical Research Foundation (MT); The Nakatomi Foundation (MT); The Takahashi Industrial Economic Research Foundation (MT); The Waksman Foundation of Japan INC (MT); Okinaka Memorial Institute for Medical Research (MT).