What question did this study set out to answer?

This study aims to understand how impaired Tregs contribute to hematopoietic stem cell depletion in pediatric aplastic anemia.

May 27, 2026Blood Research0 citationsOpen Access

The role of impaired bone marrow Tregs in hematopoietic stem cell depletion for pediatric aplastic anemia probably involves immune privilege

CHCan HuangShanghai Children's Hospital SLShanshan LiCapital Medical University JYJingwei YangShanghai Children's Hospital

Key Points

This study aims to understand how impaired Tregs contribute to hematopoietic stem cell depletion in pediatric aplastic anemia.
Detected Treg distribution via immunohistochemistry in children with aplastic anemia, myelodysplastic syndrome, and controls.
Examined T-helper cell levels and cytokines in the bone marrow using flow cytometry.
Compared long-term and short-term hematopoietic stem cell counts between groups.
AA patients had significantly lower FoxP3 + /CD4 + ratios compared to normals and MDS (P=0.014; P=0.030).
Th1 cells were dominant in AA (39.80%) compared to controls (22.1%, P<0.001), while Th2 cells were reduced (59.20% vs. 77.20%, P<0.001).
Long-term HSCs were significantly depleted in AA (0.13% vs. 1.22%, P=0.035).

Abstract

Abstract Purpose An immune-mediated pathogenesis has been postulated for aplastic anemia (AA), and impaired Tregs and other immune abnormalities have been identified in patients with AA. However, the process by which abnormal immunity specifically damages hematopoietic stem cells (HSCs) remains unclear. We conducted primary clinical studies to investigate whether the depletion of HSCs in AA could be attributed to the collapse of immune privilege (IP) afforded by regulatory T cells (Tregs). Methods The distribution of Tregs in the bone marrow of children with AA, myelodysplastic syndrome (MDS), and control participants was separately detected by immunohistochemistry. T-helper 1 (Th1), T-helper 2 (Th2), and T-helper 17 (Th17) cells, cytokines, and HSCs in the bone marrow of the AA and control groups were examined using flow cytometry. Results Patients with AA showed significantly lower FoxP3 + /CD4 + ratios (AA vs . normal: 18.09% ± 5.38% vs . 21.72% ± 4.21%, P = 0.014; AA vs. MDS: 18.09% ± 5.38% vs . 22.63% ± 5.98%, P = 0.030) and reduced Treg counts (AA vs . normal: 4.07 ± 1.41 vs . 5.25 ± 1.86 cells/HP, P = 0.014; AA vs. MDS: 4.07 ± 1.41 vs . 5.30 ± 1.49 cells/HP, P = 0.024) near the endosteum. The bone marrow in patients with AA exhibited Th1 dominance (AA vs . normal: 39.80% ± 5.20% vs . 22.1% ± 2.9% in controls, P < 0.001) and Th2 reduction (AA vs . normal: 59.20% ± 5.30% vs . 77.20% ± 2.60%, P < 0.001), indicating IP dysfunction. Significant elevation of tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and interleukin (IL)-17 levels was observed in the bone marrow of patients with AA. Long-term (LT)-HSCs were severely depleted in patients with AA (AA vs . normal: 0.13% vs . 1.22%, P = 0.035), with moderate reduction in short-term (ST)-HSCs. Conclusions Patients with AA showed endosteal Treg reduction, Th1 dominance, elevated proinflammatory cytokine levels, and severe LT-HSC depletion, linking bone marrow IP dysfunction to HSC damage. These findings provide a mechanistic explanation for the specific loss of HSCs in AA and highlight the IP niche as a therapeutic target.

اسأل الذكاء الاصطناعي

Bookmark

View Full Paper