Thrombosis is a common complication of chronic kidney disease (CKD), but the causes and mechanisms of CKD-associated thrombosis are not well clarified. Here, we show that platelet activity is remarkably enhanced in CKD mice, with increase of serum indoxyl sulfate (IS), a typical uremic toxin, which cannot be effectively cleared by routine dialysis. Ex vivo and in vitro experiments reveal that IS displays a distinct ability to enhance platelet activities, including elevated response to collagen and thrombin, increases in platelet-derived microparticles, and platelet-monocyte aggregates. The flow chamber assay and carotid artery thrombosis model demonstrate that IS-induced platelet hyperactivity contributes to thrombus formation. Further investigations disclose that reactive oxygen species (ROS)-mediated p38MAPK signaling plays a key role in IS-induced platelet hyperactivity. Moreover, we show that Klotho, which is expressed dominantly in the kidneys, has the capacity to counteract IS-induced platelet hyperactivity by inhibiting ROS/p38MAPK signaling, whereas Klotho reduction may aggravate the effect of IS on platelet activation in CKD and klotho^+/− mice. Finally, we demonstrate that Klotho protein treatment can protect against IS-induced thrombosis and atherosclerosis in apoE^−/− mice. Our findings uncover the mechanism of platelet hyperactivity induced by IS and provide new insights into the pathogenesis and treatment of CKD-associated thrombosis. Publisher9s Note: There is an Inside Blood Commentary on this article in this issue. Key Points Uremic solute IS increases platelet activity via activation of ROS/p38MAPK signaling. Klotho counteracts IS-induced thrombosis by restraining platelet hyperactivity.

Bismuth-containing nanoparticles (BNPs) are potential enhancers for tumor radiotherapy. Improving the bioavailability and developing synergistic therapeutic regimens benefit the drug transformation of BNPs. In the present study, we prepare a mesoporous silica-coated bismuth nanorod (BMSNR) camouflaged by a platelet membrane (PM). This biomimetic material is termed BMSNR@PM. The PM camouflage enhances the immune escape of the BMSNRs by lowering endocytosis by macrophages in the reticuloendothelial system. Additionally, the PM camouflage strengthens the material tumor-targeting capacity and leads to better radiotherapeutic efficacy compared with bare BMSNRs. Owing to the photothermal effect, BMSNR@PMs alters the cell cycle of 4T1 cancer cells post-treatment with 808 nm near-infrared irradiation (NIR). The proportions of S phase and G2/M phase cells decrease and increase, respectively, which explains the synergistic effect of NIR on BMSNR@PM-based radiotherapy. BMSNR@PMs efficiently eradicates cancer cells by the combined action of photothermal therapy (PTT) and radiotherapy in vivo and markedly improves the survival of 4T1-tumor-bearing mice. The synergistic therapeutic effect is superior to the outcomes of PTT and radiotherapy performed alone. Our study demonstrates a versatile bismuth-containing nanoplatform with tumor-targeting, immune escape, and radiosensitizing functionalities using an autologous cell membrane biomimetic concept that may promote the development of radiotherapy enhancers.

Chronic kidney disease (CKD) is associated with accelerated atherosclerosis progression and high incidence of cardiovascular events, hinting that atherosclerotic plaques in CKD may be vulnerable. However, its cause and mechanism remain obscure. Here, it is shown that apolipoprotein E‐deficient (ApoE^−/−) mouse with CKD (CKD/ApoE^−/− mouse) is a useful model for investigating the pathogenesis of plaque vulnerability, and premature senescence and phenotypic switching of vascular smooth muscle cells (VSMCs) contributes to CKD‐associated plaque vulnerability. Subsequently, VSMC phenotypes in patients with CKD and CKD/ApoE^−/− mice are comprehensively investigated. Using multi‐omics analysis and targeted and VSMC‐specific gene knockout mice, VSMCs are identified as both type‐I‐interferon (IFN‐I)‐responsive and IFN‐I‐productive cells. Mechanistically, mitochondrial damage resulting from CKD‐induced oxidative stress primes the cyclic GMP‐AMP synthase‐stimulator of interferon genes (cGAS‐STING) pathway to trigger IFN‐I response in VSMCs. Enhanced IFN‐I response then induces VSMC premature senescence and phenotypic switching in an autocrine/paracrine manner, resulting in the loss of fibrous cap VSMCs and fibrous cap thinning. Conversely, blocking IFN‐I response remarkably attenuates CKD‐associated plaque vulnerability. These findings reveal that IFN‐I response in VSMCs through immune sensing of mitochondrial damage is essential for the pathogenesis of CKD‐associated plaque vulnerability. Mitigating IFN‐I response may hold promise for the treatment of CKD‐associated cardiovascular diseases.

Quiescence maintenance is an important property of hematopoietic stem cells (HSCs), whereas the regulatory factors and underlying mechanisms involved in HSC quiescence maintenance are not fully uncovered. Here, we show that steroid receptor coactivator 3 (SRC-3) is highly expressed in HSCs, and SRC-3–deficient HSCs are less quiescent and more proliferative, resulting in increased sensitivity to chemotherapy and irradiation. Moreover, the long-term reconstituting ability of HSCs is markedly impaired in the absence of SRC-3, and SRC-3 knockout (SRC-3^−/−) mice exhibit a significant disruption of hematopoietic stem and progenitor cell homeostasis. Further investigations show that SRC-3 deficiency leads to enhanced mitochondrial metabolism, accompanied by overproduction of reactive oxygen species (ROS) in HSCs. Notably, the downstream target genes of peroxisome proliferator–activated receptor-coactivators 1α (PGC-1α) involved in the regulation of mitochondrial metabolism are significantly upregulated in SRC-3–deficient HSCs. Meanwhile, a significant decrease in the expression of histone acetyltransferase GCN5 accompanied by downregulation of PGC-1α acetylation is observed in SRC-3–null HSCs. Conversely, overexpression of GCN5 can inhibit SRC-3 deficiency-induced mitochondrial metabolism enhancement and ROS overproduction, thereby evidently rescuing the impairment of HSCs in SRC-3^−/− mice. Collectively, our findings demonstrate that SRC-3 plays an important role in HSC quiescence maintenance by regulating mitochondrial metabolism. Publisher9s Note: There is a Blood Commentary on this article in this issue. Key Points SRC-3 deficiency causes reduced quiescence and functional impairment of HSCs. SRC-3 participates in HSC quiescence maintenance by regulating mitochondrial metabolism. Visual Abstract

The effect of sympathetic stimulation on thrombopoiesis is not well understood. Here, we demonstrate that both continual noise and exhaustive exercise elevate peripheral platelet levels in normal and splenectomized mice, but not in dopamine β-hydroxylase–deficient (Dbh^−/−) mice that lack norepinephrine (NE) and epinephrine (EPI). Further investigation demonstrates that sympathetic stimulation via NE or EPI injection markedly promotes platelet recovery in mice with thrombocytopenia induced by 6.0 Gy of total-body irradiation and in mice that received bone marrow transplants after 10.0 Gy of lethal irradiation. Unfavorably, sympathetic stress-stimulated thrombopoiesis may also contribute to the pathogenesis of atherosclerosis by increasing both the amount and activity of platelets in apolipoprotein E–deficient (ApoE^−/−) mice. In vitro studies reveal that both NE and EPI promote megakaryocyte adhesion, migration, and proplatelet formation (PPF) in addition to the expansion of CD34⁺ cells, thereby facilitating platelet production. It is found that α2-adrenoceptor–mediated extracellular signal-regulated kinase 1/2 (ERK1/2) activation is involved in NE- and EPI-induced megakaryocyte adhesion and migration, and PPF is regulated by ERK1/2 activation-mediated RhoA GTPase signaling. Our data deeply characterize the role of sympathetic stimulation in the regulation of thrombopoiesis and reevaluate its physiopathological implications. Key Points NE and EPI promote megakaryocyte adhesion, migration, and proplatelet formation via α2-adrenoceptor-ERK1/2 signaling. Sympathetic stimulation enhances platelet production, which may facilitate recovery of thrombocytopenia or aggravate atherosclerosis.