Blood Vessels, Thrombosis & Hemostasis最新文献

Abstract

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Abstract

Posttransplant cyclophosphamide (PTCy)–based graft-versus-host disease (GVHD) prophylaxis regimens are associated with very low rates of severe acute and chronic GVHD after hematopoietic cell transplant (HCT). However, concerns about cardiac and other organ toxicities persist. This study aimed to compare the vascular biomarker profile of PTCy with other GVHD regimens, including tacrolimus/sirolimus (Tac/Sir) and tacrolimus/methotrexate (Tac/MTX), to generate hypotheses for toxicity mitigation strategies. Plasma samples from day +28 after transplant were analyzed against pretransplant baseline measurements in patients receiving PTCy-based GVHD prophylaxis as part of Blood and Marrow Transplant Clinical Trials Network (BMT CTN) 1202 (n = 112) vs Tac/MTX (n = 98) and Tac/Sir (n = 95) regimens from BMT CTN 0402. Compared with Tac/MTX, PTCy was associated with increasing angiopoietin-2 levels and decreasing epidermal growth factor levels at day +28. In contrast, Tac/Sir displayed increasing follistatin and endoglin levels and decreasing vascular endothelial growth factor receptor 2 (VEGFR2) plasma levels after HCT. Across all cohorts, increasing epidermal growth factor was protective from nonrelapse mortality, and decreasing VEGFR2 was associated with subsequent development of extensive chronic GVHD. These distinct biomarker profiles offer insights that could guide strategies to mitigate unique GVHD prophylaxis–associated toxicities.

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Abstract

Myeloproliferative leukemia protein (MPL), also known as thrombopoietin (TPO) receptor, is a class I cytokine receptor that is expressed on hematopoietic progenitors, promoting growth and differentiation toward the megakaryocyte lineage and is critical for normal platelet production. Mutations in MPL, TPO, or Janus kinase 2 (JAK2) have been implicated in multiple diseases from congenital thrombocytopenias to myeloproliferative neoplasms. The ligand for MPL, TPO, stimulates platelet production by inducing MPL dimerization and results in an active conformation that allows downstream JAK2/STAT5 signaling. Despite the biological importance of this pathway, the molecular signaling mechanism remained unclear. Here, we present a 3.39-Å cryo-electron microscopy structure of the ectodomain of mouse MPL bound to TPO. The structure revealed both low and high affinity sites between MPL and TPO that contain several pathologic mutations. To better understand TPO-driven MPL signaling, we expanded upon this structure by molecular dynamic (MD) simulations to model the full-length human MPL/TPO complex, and showed that MPL D4-D4 domain interactions are functionally relevant in activity assays. To build on our understanding of downstream activation, we added JAK2 to the MPL/TPO complex by MD simulations. This ternary complex illustrates JAK2 dimerization through the pseudokinase domain, illustrates residues important for MPL interactions, and reveals the constitutive activation mechanism of patient mutant V617F. The model also suggests the mechanism of JAK2 tyrosine kinase domain transphosphorylation. Overall, our studies illuminate TPO/MPL/JAK2 signaling mechanisms and provide additional insight into the nature of receptor signaling, which will further benefit human health.

Abstract

Complement-mediated thrombotic microangiopathy (CM-TMA) is a rare, life-threatening thrombotic microangiopathy caused by a defect in the alternative complement pathway. It is associated with renal failure and acute encephalopathy, but long-term neurocognitive effects are uncertain. Using magnetic resonance imaging (MRI) and neurocognitive tests, we can further evaluate the long-term neurocognitive complications in CM-TMA and compare them with controls. In this study, we analyzed microstructural changes in the cerebral white matter and neurocognitive testing results of patients with CM-TMA. Seven adult patients with CM-TMA in remission and 6 healthy controls were included. All patients were treated with C5 complement blockade. They were followed-up for 12 months after study entry. All patients had consecutive MRI scans (standard-of-care and quantitative sequences) to assess for white matter changes and concurrent neurocognitive testing. Patients with CM-TMA had increased white matter signal intensity in most regions of the brain compared with controls. This was accompanied by increased depression and neurocognitive dysfunction (impaired concentration, short-term memory, and verbal memory). These findings were also present up to 12 months after the initial study visit. In summary, patients with previous CM-TMA were found to have significant, albeit nonspecific, cerebral white matter abnormalities, with impaired memory and concentration. Larger studies with longitudinal follow-up to assess neurocognitive complications in CM-TMA are required. This trial was registered at Clinical Trials Ontario (ctontario.ca; project ID: 1318).

Abstract

P-selectin is a membrane glycoprotein and a member of the selectin family of cell adhesion molecules. It is prestored in α-granules of platelets and Weibel-Palade bodies of endothelial cells and is rapidly expressed on their surfaces upon activation during the course of an inflammatory response. Although a critical component of the innate immune system, the interaction of P-selectin with its cognate ligand, P-selectin glycoprotein ligand 1 (PSGL-1) may mediate maladaptive events central to the pathophysiology of venous thromboembolism, cardiovascular disease, stroke, metabolic syndrome, and sickle cell disease, among other disorders. As a consequence, a growing understanding of the significance of P-selectin and PSGL-1 in human disease has motivated the design of inhibitors that target the P-selectin/PSGL-1 pathway. Herein, we review the development and evaluation of both biologic and small-molecule inhibitors, including preclinical studies and clinical trials that have evaluated therapeutic potential of these agents for a variety of diseases linked to dysregulated inflammatory and thrombotic responses.

Abstract

We investigated the association of inferior vena cava filter (IVCF) usage with early mortality and intracranial hemorrhage (ICH) in patients with cancer and venous thromboembolism (VTE) with and without brain metastasis. We used the California Cancer Registry data linked to hospitalization and emergency department databases to identify patients (all ages) with melanoma, kidney, breast, or lung cancers who had acute VTE between 2005 and 2017 at hospital admission. The primary outcomes were 30-day mortality and 180-day ICH post-index VTE hospitalization. Of the 16 847 patients with cancer and VTE, 19.1% had brain metastasis. Patients with brain metastasis were more likely to receive an IVCF (odds ratio, 2.24; 95% confidence interval [CI], 2.01-2.50). Among patients with active bleeding, IVCF placement was associated with ∼50% reduction in 30-day mortality (hazard ratio [HR], 0.53; 95% CI, 0.42-0.68), regardless of the presence or absence of brain metastasis. In patients without active bleeding, 30-day mortality decreased by nearly 30% among those with brain metastasis who received IVCF (HR, 0.72; 95% CI, 0.60-0.85), with no difference among those without brain metastasis who had an IVCF inserted. Patients with brain metastasis had an elevated hazard of 180-day mortality (HR, 5.14; 95% CI, 2.99-8.83), but no association was found between IVCF insertion and 180-day ICH. Our study suggests a potential mortality benefit of IVCF use among patients with selected cancers and VTE, particularly among patients with active bleeding and those with brain metastasis with no bleeding. IVCF use was not associated with 180-day ICH. Randomized clinical trials are warranted to confirm our results.