CCL19 Tracks IgG4-Related Disease Activity, Supplements IgG4 Levels

Navigating the Nuances of IgG4-Related Disease Activity

IgG4-related disease (IgG4-RD) is a complex, chronic immune-mediated condition that can affect nearly any organ system, often presenting with mass-forming lesions and a variable clinical course [1]. The insidious onset and frequently asymptomatic nature of IgG4-RD pose considerable challenges for clinicians seeking to accurately assess disease activity and monitor treatment response [2, 1]. Because management often involves prolonged courses of glucocorticoids and other immunosuppressants with significant adverse effects, precise monitoring is essential to minimize toxicity while ensuring disease control [3, 4]. The need for reliable biomarkers that dynamically reflect disease activity and predict relapse is therefore paramount for guiding therapeutic decisions, and a recent study has identified a potential new candidate to aid in this effort [5, 6].

Screening for Biomarkers in IgG4-Related Disease

To address the monitoring challenges in IgG4-related disease (IgG4-RD), researchers sought to identify biomarkers capable of distinguishing active disease from remission. The investigation began with a broad screening phase, measuring ninety-two inflammation-associated proteins in a discovery cohort of 67 patients with IgG4-RD. For comparison, the cohort also included 49 healthy donors and 21 patients with sarcoidosis, a granulomatous condition often included in the differential diagnosis. The resulting protein data underwent rigorous statistical analysis, carefully adjusted for age, sex, and race, with an additional correction for the false discovery rate to minimize the risk of chance findings from multiple comparisons. The team then used specific analytical techniques to isolate the most relevant proteins. These included unsupervised hierarchical clustering, a method that groups individuals based on shared protein profiles without relying on pre-existing clinical labels, and receiver operator characteristic curves, a standard statistical tool for evaluating a biomarker's ability to accurately distinguish between patient and control groups.

Identifying Key Inflammatory Markers

From the initial screening, the analysis successfully narrowed the field to twelve inflammation-associated proteins that distinguished IgG4-RD from both healthy controls and patients with sarcoidosis. The researchers noted that most of these markers correlated with one another, suggesting they are part of an interconnected inflammatory network characteristic of the disease. Further statistical refinement highlighted three specific chemokines, which are signaling proteins that attract immune cells, as being particularly effective at identifying the disease: CCL19, CCL2, and CCL13 were the most distinguishing of IgG4-RD. To confirm these initial findings, the researchers performed a validation study using a quantitative enzyme-linked immunosorbent assay (ELISA). This second phase involved a larger, separate cohort of 80 patients with IgG4-RD and 80 age, sex, and race-matched healthy donors. Crucially, this validation cohort included 28 patients with paired longitudinal samples, allowing for the assessment of biomarker changes within the same individuals over time.

CCL19: A Dynamic Indicator of Disease Activity

Among the three leading candidate chemokines, C-C motif chemokine ligand 19 (CCL19) demonstrated a unique and clinically relevant behavior. While all three were elevated in IgG4-RD, the study found that only CCL19 decreased during treatment-induced remission relative to active IgG4-RD. This dynamic response suggests CCL19 levels may directly reflect therapeutic efficacy, a quality not observed in CCL2 or CCL13. Further strengthening its clinical potential, serum CCL19 levels correlated with established clinical and laboratory parameters of disease activity and severity. The systemic elevation of CCL19 was subsequently confirmed via quantitative ELISA. The analysis also revealed that CCL19's performance mirrored that of the current standard, serum IgG4 levels; specifically, CCL19 performed similarly to IgG4 in dynamically declining in response to treatment and increasing with subsequent relapse. Importantly, the study showed that CCL19 and IgG4 supplemented one another in distinguishing active disease from remission. This suggests that combining the two markers could provide a more sensitive and reliable assessment of disease status than either marker alone. The findings position CCL19 as a significant biomarker for the longitudinal monitoring of disease activity in patients with IgG4-RD, one that may provide supplemental value to IgG4 in identifying relapsing disease and helping to guide treatment adjustments.

References

1. Bonaso F, Jiang B, Yockey LJ, et al. Broad screening of inflammation-associated proteins identifies serum CCL19 as a novel biomarker of disease activity in IgG4-related disease.. Annals of the rheumatic diseases. 2026. doi:10.1016/j.ard.2026.03.015

2. Tang J, Cai S, Ye C, Dong L. Biomarkers in IgG4-related disease: A systematic review.. Seminars in arthritis and rheumatism. 2020. doi:10.1016/j.semarthrit.2019.06.018

3. Geertsema-Hoeve BC, Laar JAMV, Raaphorst J, et al. Multicentre, 26-week, open-label phase 2 trial of the JAK inhibitor filgotinib in Behçet's disease, idiopathic inflammatory myopathies and IgG4-related disease: DRIMID study protocol.. BMJ open. 2025. doi:10.1136/bmjopen-2024-089827

4. Tanaka T, Narazaki M, Kishimoto T. IL-6 in Inflammation, Immunity, and Disease. Cold Spring Harbor Perspectives in Biology. 2014. doi:10.1101/cshperspect.a016295

5. Qiu S, Cai Y, Yao H, et al. Small molecule metabolites: discovery of biomarkers and therapeutic targets. Signal Transduction and Targeted Therapy. 2023. doi:10.1038/s41392-023-01399-3

6. Liu B, Zhou H, Tan L, Siu KTH, Guan X. Exploring treatment options in cancer: tumor treatment strategies. Signal Transduction and Targeted Therapy. 2024. doi:10.1038/s41392-024-01856-7