Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Chongqing Clinical Research Center of Kidney and Urology Diseases, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China.
State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury, Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Army Medical University (Third Military Medical University), Chongqing, China.
J Thromb Haemost. 2022 Dec;20(12):2972-2987. doi: 10.1111/jth.15876. Epub 2022 Sep 23.
Thrombosis and hemorrhage as two opposite pathologies are prevalent within the chronic kidney disease (CKD) population. Platelet homeostasis, which positions centrally in their pathogenesis, varies among the CKD population, while the underlying mechanism is poorly understood.
To investigate the change character and mechanism of platelet homeostasis in CKD and its association with renal Klotho deficiency.
The change character of platelet homeostasis and its association with renal Klotho deficiency were determined based on a cohort study as well as CKD mice and Klotho-deficient mice with CKD. The effects on thrombopoiesis and platelet lifespan were examined by flow cytometry and platelet transfer. The underlying mechanism was explored by proteomics, flow cytometry, western blot, and immunoprecipitation.
We show that platelet count declines both in patient and mouse models with advanced CKD (Adv-CKD) and is positively associated with circulating Klotho levels. Mechanistically, we identify that ubiquitin ligase UBE2O governs Bcl-xL ubiquitination and degradation in platelets, whereas Adv-CKD-induced oxidative stress in platelets stimulates p38MAPK to promote Bcl-xL phosphorylation, which facilitates UBE2O binding to Bcl-xL and subsequent Bcl-xL degradation. Consequently, platelet lifespan is shortened in Adv-CKD, culminating in platelet count decline. However, kidney-secreted soluble Klotho protein restricts oxidative stress in platelets, thereby preserving Bcl-xL expression and platelet lifespan.
Our findings uncover the mechanism of platelet count decline in Adv-CKD and identify renal Klotho as a long-range regulator of platelet lifespan, which not only provide a molecular mechanism underlying CKD-associated thrombocytopenia and hemorrhage but also offer a promising therapy choice.
血栓形成和出血是慢性肾脏病（CKD）患者中两种常见的相反病理过程。血小板的内稳态在其发病机制中处于核心地位，而 CKD 患者的血小板内稳态存在差异，但其潜在机制尚不清楚。
探讨 CKD 患者血小板内稳态的变化特征及其与肾脏 Klotho 缺乏的关系。
通过队列研究以及 CKD 小鼠和 Klotho 缺陷型 CKD 小鼠模型，确定血小板内稳态的变化特征及其与肾脏 Klotho 缺乏的关系。通过流式细胞术和血小板转移来研究对巨核细胞生成和血小板寿命的影响。通过蛋白质组学、流式细胞术、Western blot 和免疫沉淀来探讨潜在机制。
我们表明，在晚期 CKD（Adv-CKD）患者和小鼠模型中，血小板计数均下降，且与循环 Klotho 水平呈正相关。从机制上讲，我们发现泛素连接酶 UBE2O 调节血小板中 Bcl-xL 的泛素化和降解，而 Adv-CKD 诱导的血小板氧化应激刺激 p38MAPK 促进 Bcl-xL 磷酸化，从而促进 UBE2O 与 Bcl-xL 结合及随后的 Bcl-xL 降解。因此，Adv-CKD 中血小板寿命缩短，导致血小板计数下降。然而，肾脏分泌的可溶性 Klotho 蛋白限制了血小板中的氧化应激，从而维持 Bcl-xL 的表达和血小板寿命。
我们的研究结果揭示了 Adv-CKD 中血小板计数下降的机制，并确定肾脏 Klotho 是血小板寿命的远程调节因子，这不仅为 CKD 相关血小板减少症和出血症提供了分子机制，也为治疗提供了有希望的选择。
