Integrin αvβ8–mediated TGF-β1 activation regulates the sustained response in immune thrombocytopenia after TPO-RA withdrawal

作者：Heng Mei, Min Xu, Jinhui Shu, Lu Tang, Qinying Xie, Lili Luo, Qiuzhe Wei, Huiwen Jiang, Zhangyin Ming, Yu Hu · 发表于：Blood · 年份：2025 · DOI：10.1182/blood.2025029769 · 被引用次数：4 · 研究领域：Platelet Disorders and Treatments、Cell Adhesion Molecules Research、Blood groups and transfusion

ABSTRACT: Only 30% to 50% of patients with immune thrombocytopenia (ITP) exhibit a sustained response upon thrombopoietin receptor agonists (TPO-RA) withdrawal, underscoring the necessity for mechanistic elucidation. We enrolled 49 patients treated with TPO-RA for 4 months and performed a follow-up study for 3 months, classifying them into sustained responders (n = 21), and nonsustained responders (n = 28). Compared with total transforming growth factor β1 (TGF-β1) levels, activated TGF-β1 levels (3854 ± 4380 vs 943 ± 1500 pg/mL; P< .001) were significantly elevated in sustained responders, with integrin αvβ8 regulating TGF-β1 activation and restoring immune tolerance. We established a passive ITP model using platelet factor 4-TGF-β1 conditional knockout (CKO) mice, which exhibited a shorter duration of sustained response than wild-type (WT) mice. CKO mice demonstrated a reduced regulatory T-cell (Treg) population, an increased M1-to-M2 macrophage ratio, and more severe megakaryocyte destruction after anti-CD41 injection. Exogenous administration of αvβ8 (250 ng/kg) effectively activated TGF-β1 and prolonged remission after TPO discontinuation in WT mice. Additionally, CD4+ T cells were transfected with lentiviral small interfering RNA or short hairpin RNA to modulate integrin β8 expression and these were injected into severe combined immunodeficiency mice undergoing an active model of ITP. Results showed that β8 overexpression increased Tregs and reduced megakaryocyte damage...