Project description:Antiphospholipid syndrome (APS) is associated with arterial and venous thrombosis. The unfavorable fibrin clot phenotype, including formation of dense and poorly lysable clots, has been reported both in thrombotic APS and venous thromboembolism (VTE). The presence and amount of different proteins within a plasma clot, not only associated with the coagulation system, may influence clot properties. To our knowledge, there is a lack of data on plasma fibrin-clot bound proteins in patients with thrombotic APS or VTE. The aim of our study was to perform a quantitative proteomic analysis of fibrin clots prepared from citrated plasma from subjects with thrombotic APS and prior VTE, along with fibrin clot permeability (Ks) and clot lysis time (CLT) assessed ex vivo. We investigated 23 consecutive patients with APS, 18 with a history of first-ever VTE, and 20 age and sex matched healthy subjects. A multiple enzyme digestion filter aided sample preparation and a multienzyme digestion (MED) FASP method combined with LC-MS/MS analysis performed on a Proxeon Easy-nLC System coupled to the Q Exactive HF mass spectrometer were used. The proteomic analysis revealed that clot composition regarding 117 proteins in APS patients and 48 proteins in VTE patients was changed as compared to healthy controls, while 72 clot-bounded proteins differed between APS and VTE subjects. In healthy controls, Ks was associated with fibrinogen alpha and gamma chains (r=0.46 and r=0.46, both p<0.05, respectively) or apolipoprotein B-100 (r=-0.53, p<0.05), while CLT correlated with annexin A2 (r=-0.58, p<0.05), apolipoportein(a) (r=0.47, p<0.05), or platelet glycoprotein 4 (r=0.59, p<0.05). In VTE patients correlations of Ks with complement C1q and histone H2B, as factors closely linked with thrombosis, were observed (r=-0.52 and r=-0.47, both p<0.05, respectively). In patients with thrombotic APS all above-mentioned associations were not found. This study is the first to show that different proteins are able to influence the clot formation, structure, and properties. Since, prothrombotic conditions abolished associations observed in healthy subjects fibrin clots, differences in protein clot components might explain the links between prothrombotic fibrin clot phenotype and thromboembolic events.

Project description:Formation and maturation of a functional blood vascular system is required for the development and maintenance of all tissues in the body. During the process of blood vessel development, primordial endothelial cells are formed and become specified toward arterial or venous fates to generate a circulatory network that provides nutrients and oxygen to, and removes metabolic waste from, all tissues. Specification of arterial and venous endothelial cells occurs in conjunction with suppression of endothelial cell cycle progression, and endothelial cell hyperproliferation is associated with potentially lethal arterial-venous malformations. However, the mechanistic role that cell cycle state plays in arterial-venous specification is unknown. Herein, studying retinal vascular development in Cdh5-CreERT2;R26FUCCI2aR reporter mice, we found that venous and arterial endothelial cells are in distinct cell cycle states during development and in adulthood. That is, venous endothelial cells reside in early G1 state, while arterial endothelial cells reside in late G1 state. Single cell RNA sequencing of developing retinal endothelial cells revealed that BMP signaling and early G1 state are enriched in venous endothelial cells, while TGF-b signaling and late G1 state are enriched in arterial endothelial cells. Cultured endothelial cells in early vs. late G1 exhibited significant differences in gene expression and activity, especially among BMP/TGF-b signaling components. The early G1 state was found to be essential for BMP4-induced venous gene expression, whereas late G1 state is essential for TGF-b1-induced arterial gene expression. In a mouse model of endothelial cell hyperproliferation and disrupted arterial-venous specification, pharmacological inhibition of endothelial cell cycle prevented the vascular defects. Collectively, our results show that endothelial cell cycle control plays a key role in arterial-venous network formation, and distinct cell cycle states provide distinct windows of opportunity for the molecular induction of arterial vs. venous specification.

Project description:Formation and maturation of a functional blood vascular system is required for the development and maintenance of all tissues in the body. During the process of blood vessel development, primordial endothelial cells are formed and become specified toward arterial or venous fates to generate a circulatory network that provides nutrients and oxygen to, and removes metabolic waste from, all tissues. Specification of arterial and venous endothelial cells occurs in conjunction with suppression of endothelial cell cycle progression, and endothelial cell hyperproliferation is associated with potentially lethal arterial-venous malformations. However, the mechanistic role that cell cycle state plays in arterial-venous specification is unknown. Herein, studying vascular development in Cdh5-CreERT2;R26FUCCI2aR reporter mice, we find that venous and arterial endothelial cells exhibit a propensity for different cell cycle states during development and in adulthood. That is, venous endothelial cells are predominantly FUCCI-Negative, while arterial endothelial cells are enriched for the FUCCI-Red reporter. Single cell RNA sequencing analysis of developing retinal endothelial cells reveals that venous endothelial cells are enriched for the FUCCI-Negative state and BMP signaling, while arterial endothelial cells are enriched for the FUCCI-Red state and TGF-b signaling. Further transcriptional analyses and live imaging of cultured endothelial cells expressing the FUCCI reporter show that reporter-negative corresponds to an early G1 state and reporter-red corresponds to late G1 state. We find the early G1 state is essential for BMP4-induced venous gene expression, whereas late G1 state is essential for TGF-b1-induced arterial gene expression. In a mouse model of endothelial cell hyperproliferation and disrupted arterial-venous specification, pharmacological inhibition of endothelial cell cycle prevents the vascular defects. Collectively, our results show that endothelial cell cycle control plays a key role in arterial-venous network formation, and distinct cell cycle states provide distinct windows of opportunity for the molecular induction of arterial vs. venous specification.

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