Biology subjects

Cines, D. B.

Publications and source records attributed to Cines, D. B..

6 recordsLinked to original sources

bioRxiv2025

Antiphospholipid syndrome (APS) is a platelet factor 4 (PF4)-centric immunothrombotic disorder

Antiphospholipid syndrome (APS) is an immunothrombotic disorder, frequently attributed to autoantibodies that bind {beta}2-glycoprotein I ({beta}2GPI). A study showed that the platelet-specific chemokine, platelet factor 4 (PF4), binds to {beta}2GPI, enhancing recognition of {beta}2GPI by APS antibodies. APS antibodies induce the release of neutrophil extracellular traps (NETs), webs of decondensed chromatin that bind both PF4 and {beta}2GPI. We propose that PF4 bridges {beta}2GPI to NETs (and other PF4-targeted polyanions), leading to the formation of prothrombotic PF4:{beta}2GPI:NET immunotargets in APS. Dynamic light-scattering studies of isolated IgGs from four patients with triple-positive APS show formation of PF4:{beta}2GPI:NET complexes that bind APS antibodies. NETs released in a microfluidic system bound {beta}2GPI, but only in the presence of PF4, forming a multimolecular APS antigenic target. Whole blood infused through a photochemically-injured, endothelium-lined microfluidic channel formed platelet-, fibrin-, and complement-rich thrombi that bound APS antibody only in the presence of PF4. Thrombi were reduced in size if either ADAMTS13 or DNase1 was infused. In a murine APS model, wildtype and transgenic mice expressing platelet human PF4 {+/-} Fc{gamma}RIIA developed more intense neutrophil rolling along veins, and more extensive thrombus formation following laser injury to cremaster arterioles and venules, whereas mice lacking PF4 did not. Three antigenically distinct anti-hPF4 monoclonal antibodies blocked thrombosis in vitro, and neutrophil rolling and thrombosis in vivo. Our studies provide new insights into the basis of APS that has mechanistic parallels to other known PF4 immunothrombotic disorders and offer potential diagnostic and non-anticoagulant therapeutic strategies for clinical management. Key pointsO_LIPF4 enhances {beta}2GPI binding to NETs and these complexes are central to APS immunothrombosis. C_LIO_LIAnti-PF4 monoclonal antibodies block APS immunothrombosis in microfluidic and murine studies. C_LI

cell biology↗

bioRxiv2023

Packaging of supplemented urokinase into naked alpha-granules of in vitro-grown megakaryocytes for targeted therapeutic delivery

Our prior finding that uPA endogenously expressed and stored in the platelets of transgenic mice prevented thrombus formation without causing bleeding, prompted us to develop a potentially clinically relevant means of generating anti-thrombotic human platelets in vitro from CD34+ hematopoietic cell-derived megakaryocytes. CD34+-megakaryocytes internalize and store in -granules single-chain uPA (scuPA) and a uPA variant modified to be plasmin-resistant, but thrombin-activatable, (uPAT). Both uPAs co-localized with internalized factor V (FV), fibrinogen and plasminogen, low-density lipoprotein receptor-related protein 1 (LRP1), and interferon-induced transmembrane protein 3 (IFITM3), but not with endogenous von Willebrand factor (VWF). Endocytosis of uPA by CD34+-\megakaryocytes was mediated in part via LRP1 and IIb{beta}3. scuPA-containing megakaryocytes degraded endocytosed intragranular FV, but not endogenous VWF, in the presence of internalized plasminogen, whereas uPAT-megakaryocytes did not significantly degrade either protein. We used a carotid-artery injury model in NOD-scid IL2r{gamma}null (NSG) mice homozygous for VWFR1326H (a mutation switching binding VWF specificity from mouse to human glycoprotein IbmlIX) to test whether platelets derived from scuPA-MKs or uPAT-Mks would prevent thrombus formation. NSG/VWFR1326H mice exhibited a lower thrombotic burden after carotid artery injury compared to NSG mice unless infused with human platelets or MKs, whereas intravenous injection of either uPA-containing megakaryocytes into NSG/VWFR1326H generated sufficient uPA-containing human platelets to lyse nascent thrombi. These studies suggest the potential to deliver uPA or potentially other ectopic proteins within platelet -granules from in vitro-generated megakaryocytes. Key pointsO_LIUnlike platelets, in vitro-grown megakaryocytes can store exogenous uPA in its -granules. C_LIO_LIuPA uptake involves LRP1 and IIb{beta}3 receptors and is functionally available from activated platelets. C_LI

cell biology↗

bioRxiv2023

PAI-1 Deficiency Drives Pulmonary Vascular Smooth Muscle Remodeling and Pulmonary Hy-pertension

Pulmonary arterial hypertension (PAH) is a progressive and potentially a rapidly fatal disease characterized by vasoconstriction and remodeling of small pulmonary arteries (PA) leading to increased pulmonary vascular resistance and right heart failure. Central to the remodeling process is a switch of the smooth muscle cells in small PAs (PASMC) to a proliferative, apoptosis-resistant phenotype. There is reason to suspect that the plasminogen activator system may play an important role in the remodeling program in PAH based on its roles in vascular post-injury restenosis, fibrosis, angiogenesis and tumorigenesis. Plasminogen activator inhibitor-1 (PAI-1) is the primary physiological inhibitor of the plasminogen activators - urokinase-type and tissue-type (uPA and tPA, respectively). Immunohisto- chemical and immunoblot analyses revealed that PAI-1 was deficient in smooth muscle areas of small remodeled PAs and early-passage PASMC from subjects with PAH compared to non-PAH controls. PAI1-/- male and female mice developed spontaneous pulmonary vascular remodeling and pulmonary hypertension (PH) as evidenced by significant increase in PA medial thickness, systolic right ventricular pressure, and right ventricular hypertrophy. Lastly, the uPA inhibitors upamostat (WX-671) and amiloride analog BB2-30F down-regulated mTORC1 and SMAD3, restored PAI-1 levels, reduced proliferation, and induced apoptosis in human PAH PASMC. We examined the effect of inhibition of uPA catalytic activity by BB2-30F on the development of SU5416/Hypoxia (SuHx)-induced PH in mice. Vehicletreated SuHx-exposed mice had up-regulated mTORC1 in small PAs, developed pulmonary vascular remodeling and PH, as evidenced by significant increase of PA MT, sRVP, RV hypertrophy, and a significant decrease in the pulmonary artery acceleration time/pulmonary ejection time (PAAT/PET) ratio compared to age- and sex-matched normoxia controls, whereas BB2-30F-treated group was protected from all these pathological changes. Taken together, our data strongly suggest that PAI-1 down- regulation in PASMC from human PAH lungs promotes PASMC hyper-proliferation, remodeling, and spontaneous PH due to unopposed uPA activation. Further studies are needed to determine the potential benefits of targeting the PAI-1/uPA imbalance to attenuate the progression and/or reverse pulmonary vascular remodeling and PH.

cell biology↗

bioRxiv2023

Neutrophil extracellular trap stabilization by platelet factor 4 reduces thrombogenicity and endothelial cell injury

Neutrophil extracellular traps (NETs) are abundant in sepsis, and proposed NET-directed therapies in sepsis prevent their formation or accelerate degradation. Yet NETs are important for microbial entrapment, as NET digestion liberates pathogens and NET degradation products (NDPs) that deleteriously promote thrombosis and endothelial cell injury. We proposed an alternative strategy of NET-stabilization with the chemokine, platelet factor 4 (PF4, CXCL4), which we have shown enhances NET-mediated microbial entrapment. We now show that NET compaction by PF4 reduces their thrombogenicity. In vitro, we quantified plasma thrombin and fibrin generation by intact or degraded NETs and cell-free (cf) DNA fragments, and found that digested NETs and short DNA fragments were more thrombogenic than intact NETs and high molecular weight genomic DNA, respectively. PF4 reduced the thrombogenicity of digested NETs and DNA by interfering, in part, with contact pathway activation. In endothelial cell culture studies, short DNA fragments promoted von Willebrand factor release and tissue factor expression via a toll-like receptor 9-dependent mechanism. PF4 blocked these effects. Cxcl4-/- mice infused with cfDNA exhibited higher plasma thrombin anti-thrombin (TAT) levels compared to wild-type controls. Following challenge with bacterial lipopolysaccharide, Cxcl4-/- mice had similar elevations in plasma TAT and cfDNA, effects prevented by PF4 infusion. Thus, NET-stabilization by PF4 prevents the release of short fragments of cfDNA, limiting the activation of the contact coagulation pathway and reducing endothelial injury. These results support our hypothesis that NET-stabilization reduces pathologic sequelae in sepsis, an observation of potential clinical benefit. HIGHLIGHTSO_LIIn contrast to intact NETs, degraded NETs and cfDNA are prothrombotic and injure the endothelium. C_LIO_LIPF4 reduces the ability of degraded NETs and cfDNA to promote thrombosis and injure the endothelium. C_LI

cell biology↗

bioRxiv2022

Prevention of thrombocytopenia and thrombosis in heparin-induced thrombocytopenia (HIT) using deglycosylated KKO: A novel therapeutic?

Heparin-induced thrombocytopenia (HIT) is characterized by mild thrombocytopenia associated with a highly prothrombotic state due to the development of pathogenic antibodies that recognize human (h) platelet factor 4 (PF4) complexed with various polyanions. While non-heparin anticoagulants and intravenous immunoglobulin (IVIG) are the mainstay of care, bleeding may develop, and risk of new thromboembolic events remain. We had described a mouse IgG{kappa}2b antibody KKO that mimics the sentinel features of pathogenic HIT antibodies, including binding to the same neoepitope on hPF4:polyanion complexes. KKO, like HIT IgGs, activates platelets through Fc{gamma}RIIA and induces complement activation. We now asked whether Fc-modified KKO can be used as a novel therapeutic to prevent or treat HIT. Using the endoglycosidase EndoS, we created deglycosylated KKO (DGKKO). DGKKO bound to PF4-polyanion complexes, and blocked Fc{gamma}RIIA-dependent activation of PF4 treated platelets by KKO, 5B9 (another HIT-like monoclonal antibody), and isolated IgGs from HIT patients. DGKKO also decreased complement activation and deposition of C3c on platelets. Injection of DGKKO into "HIT mice" lacking mouse PF4, but transgenic for hPF4 and Fc{gamma}RIIA, prevented and reversed thrombocytopenia when injected before or after KKO, 5B9 or HIT IgG, respectively, in a microfluidic system. DGKKO reversed antibody-induced thrombus growth in HIT mice. In contrast, DGKKO was ineffective in preventing thrombosis by IgG from a patient with the HIT-related disorder, vaccine-induced immune thrombotic thrombocytopenia. Thus, DGKKO may represent a new class of therapeutics for targeted treatment of patients with HIT. Key PointsO_LIDeglycosylated (DG) KKO can reverse thrombocytopenia in a HIT murine model. C_LIO_LIDGKKO can prevent/reverse thrombosis in vitro and in a HIT murine model. C_LI

cell biology↗

bioRxiv2020

Precision targeting of the Plasminogen Activator Inhibitor-1 mechanism increases efficacy of fibrinolytic therapy in empyema.

Plasminogen activator inhibitor-1 (PAI-1) is an endogenous irreversible inhibitor of tissue-type (tPA) and urokinase (uPA) plasminogen activators. PAI-1-targeted fibrinolytic therapy (PAI-1-TFT) is designed to decrease the therapeutic dose of tPA and uPA to attenuate the risk of bleeding and other complications. The docking site peptide (DSP) is a part of the PAI-1 reactive center loop, which interacts with plasminogen activators, thus affecting the PAI-1 mechanism. We used DSP for PAI-1-TFT in two rabbit models: chemically-induced pleural injury and Streptococcus pneumoniae induced empyema. PAI-1-TFT with DSP combined with single chain uPA or tPA resulted in an up to 8-fold decrease in the minimal effective therapeutic dose of plasminogen activator and induced no bleeding. An increase in the level of PAI-1 in infectious pleural injury, when compared to chemically-induced injury, coincided with an increase in the minimal effective dose of plasminogen activator and DSP. PAI-1 is a valid molecular target in S. pneumoniae empyema model in rabbits, which closely recapitulates key characteristics of empyema in humans. Low dose PAI-1-TFT is a novel precise interventional strategy that may improve fibrinolytic therapy of empyema in clinical practice.

biochemistry↗