Plain-language summary
Chronic kidney disease often progresses because of renal interstitial fibrosis, and persistent inflammation is a major force behind that scarring. This study examined soluble PD-1 (sPD-1), a circulating form of an immune checkpoint protein, and asked whether it helps push the kidney toward fibrosis. Working with serum and kidney biopsy samples from patients with chronic kidney disease, plus three distinct mouse models - ureteral obstruction, ischemia-reperfusion injury, and aristolochic acid-induced nephropathy - the authors found that higher sPD-1 levels tracked with more severe fibrosis and greater T-cell activation, and that adding extra sPD-1 worsened scarring. They then built "Exo-PD1": an engineered extracellular vesicle surface-functionalized with avidin so that anti-PD-1 antibodies could be loaded onto it. Acting as a circulating sink, Exo-PD1 captured sPD-1 more effectively than free antibodies through local adsorption. In treated animals it reduced T-cell hyperactivation and inflammatory responses, lowered the fibrotic markers alpha-SMA and collagen I across all three models, and produced minimal systemic toxicity, pointing to a vesicle-based way of intercepting a soluble immune mediator rather than blocking a cell-surface receptor.
Key findings
- Elevated soluble PD-1 correlated with the severity of renal interstitial fibrosis and with T-cell hyperactivation in both patients with chronic kidney disease and three mouse models, while exogenous soluble PD-1 aggravated fibrosis.
- The authors engineered "Exo-PD1" by surface-functionalizing extracellular vesicles with avidin to load anti-PD-1 antibodies, creating a platform intended to sequester circulating soluble PD-1.
- Exo-PD1 outperformed conventional antibodies at capturing soluble PD-1 through local adsorption, and significantly attenuated T-cell hyperactivation and inflammatory responses in vitro and in vivo.
- Treatment reduced the fibrotic markers alpha-SMA and collagen I across the ureteral obstruction, ischemia-reperfusion and aristolochic acid models with minimal systemic toxicity.
Original abstract
Aims: Renal interstitial fibrosis (RIF) drives chronic kidney disease (CKD) progression, with elevated soluble PD-1 (sPD-1) exacerbating chronic inflammation. This study aims to elucidate the pathogenic role of sPD-1 in RIF and evaluate "Exo-PD1"-a novel engineered extracellular vesicle strategy designed to sequester circulating sPD-1-as a targeted therapeutic intervention to mitigate renal fibrosis. Materials And Methods: We analyzed serum and renal biopsy samples from clinical CKD cohorts and three distinct mouse models-unilateral ureteral obstruction (UUO), unilateral ischemia-reperfusion injury (UIRI), and aristolochic acid I (AAI)-induced nephropathy-using ELISA, immunohistochemistry, and flow cytometry. Exo-PD1 was engineered by surface-functionalizing extracellular vesicles with avidin to load anti-PD-1 antibodies. The therapeutic efficacy and safety profiles of Exo-PD1 were systematically evaluated in vitro and in vivo. Key Findings: Elevated sPD-1 strongly correlated with RIF severity and T-cell hyperactivation in both patients and murine models, while exogenous sPD-1 exacerbated fibrosis. Exo-PD1 effectively sequestered circulating sPD-1, outperforming conventional antibodies through local adsorption. Furthermore, Exo-PD1 treatment significantly attenuated T-cell hyperactivation, blunted inflammatory responses, and reduced key fibrotic markers (α-SMA, collagen I) across models with minimal systemic toxicity. Significance: sPD-1 acts as a critical mediator of renal fibrosis by disrupting immune homeostasis. The biocompatible Exo-PD1 platform effectively intercepts circulating sPD-1, disrupting the inflammation-fibrosis crosstalk and offering a highly translational therapeutic approach to halt CKD progression.
Frequently asked questions
What did this study find?
Chronic kidney disease often progresses because of renal interstitial fibrosis, and persistent inflammation is a major force behind that scarring. This study examined soluble PD-1 (sPD-1), a circulating form of an immune checkpoint protein, and asked whether it helps push the kidney toward fibrosis. Working with serum and kidney biopsy samples from patients with chronic kidney disease, plus three distinct mouse models - ureteral obstruction, ischemia-reperfusion injury, and aristolochic acid-induced nephropathy - the authors found that higher sPD-1 levels tracked with more severe fibrosis and greater T-cell activation, and that adding extra sPD-1 worsened scarring. They then built "Exo-PD1": an engineered extracellular vesicle surface-functionalized with avidin so that anti-PD-1 antibodies could be loaded onto it. Acting as a circulating sink, Exo-PD1 captured sPD-1 more effectively than free antibodies through local adsorption. In treated animals it reduced T-cell hyperactivation and inflammatory responses, lowered the fibrotic markers alpha-SMA and collagen I across all three models, and produced minimal systemic toxicity, pointing to a vesicle-based way of intercepting a soluble immune mediator rather than blocking a cell-surface receptor.
Was this tested in humans or in the laboratory?
This is preclinical work — the findings come from laboratory models, not from human participants.
Where can I read the original paper?
The full text lives with the publisher: https://doi.org/10.1016/j.lfs.2026.124556
How to cite this paper
Zhang Yuting, Peng Hongbin, Mi Xue, Li Jipeng, Zha Yang, Wu Mengting et al.. Soluble PD-1 drives renal fibrosis in CKD by disrupting immune homeostasis: Therapeutic mitigation via a targeted sPD-1 sequestration strategy.. Life sciences. 2026, 2026-06-27. DOI: 10.1016/j.lfs.2026.124556
Source & verification
- Journal: Life sciences
- Published: 27 June 2026
- DOI: 10.1016/j.lfs.2026.124556
- PubMed ID: 42364692
- Indexed via: pubmed
- MeSH terms: Animals, Programmed Cell Death 1 Receptor, Mice, Fibrosis, Humans, Renal Insufficiency, Chronic, Male, Kidney, Homeostasis, Disease Models, Animal, Female, Mice, Inbred C57BL