Von Willebrand factor and the thrombophilia of severe COVID-19: in situ evidence from autopsies.

Background: COVID-19 is accompanied by a hypercoagulable state and characterized by microvascular and macrovascular thrombotic complications. In plasma samples from patients with COVID-19, von Willebrand factor (VWF) levels are highly elevated and predictive of adverse outcomes, especially mortality. Yet, VWF is usually not included in routine coagulation analyses, and histologic evidence of its involvement in thrombus formation is lacking. Objectives: To determine whether VWF, an acute-phase protein, is a bystander, ie, a biomarker of endothelial dysfunction, or a causal factor in the pathogenesis of COVID-19. Methods: We compared autopsy samples from 28 patients with lethal COVID-19 to those from matched controls and systematically assessed for VWF and platelets by immunohistochemistry. The control group comprised 24 lungs, 23 lymph nodes, and 9 hearts and did not differ significantly from the COVID-19 group in age, sex, body mass index (BMI), blood group, or anticoagulant use. Results: In lungs, assessed for platelets by immunohistochemistry for CD42b, microthrombi were more frequent in patients with COVID-19 (10/28 [36%] vs 2/24 [8%]; P = .02). A completely normal pattern of VWF was rare in both groups. Accentuated endothelial staining was found in controls, while VWF-rich thrombi were only found in patients with COVID-19 (11/28 [39%] vs 0/24 [0%], respectively; P < .01), as were NETosis thrombi enriched with VWF (7/28 [25%] vs 0/24 [0%], respectively; P < .01). Forty-six percent of the patients with COVID-19 had VWF-rich thrombi, NETosis thrombi, or both. Trends were also seen in pulmonary draining lymph nodes (7/20 [35%] vs 4/24 [17%]; P = .147), where the overall presence of VWF was very high. Conclusion: We provide in situ evidence of VWF-rich thrombi, likely attributable to COVID-19, and suggest that VWF may be a therapeutic target in severe COVID-19.

Treosulfan-based Reduced-intensity Allogeneic Hematopoietic Cell Transplantation in Adults With Primary Immunodeficiency: A Case Series.

BACKGROUND/AIM: We report three adult patients with primary immunodeficiency (PID) treated with reduced-intensity allogenic hematopoietic cell transplantation (HCT) with fludarabine/treosulfan conditioning and graft-versus-host disease (GvHD) prophylaxis with alemtuzumab and a calcineurin inhibitor. CASE REPORT: Patient 1, a 51-year-old male, had common variable immunodeficiency (CVID) with protein-losing enteropathy. Patient 2 was a 29-year-old woman with STAT3 (signal transducer and activator of transcription 3)-dependent hyper-IgE syndrome (HIES). Patient 3 was a 25-year-old male with XIAP (X-linked inhibitor of apoptosis)-deficiency presenting as treatment-refractory granulomatous enteropathy. Engraftment occurred in all three patients, with 100% donor chimerism in blood. Two patients survived, whereas the patient with CVID died due to infection. CONCLUSION: This series highlights issues of transplantation for PID in adults and treosulfan-based conditioning, which is feasible for PID patients; infectious complications are the major issue of concern.

Daratumumab for immune thrombotic thrombocytopenic purpura.

Immune thrombotic thrombocytopenic purpura (iTTP) is a life-threatening thrombotic microangiopathy. It is caused by a severe ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 motifs, 13) deficiency due to circulating autoantibodies, and is associated with significant morbidity and mortality. Current treatment options include plasma exchange, immunosuppression, and caplacizumab. When remission is achieved, the risk of relapse is high, especially in patients with persistent ADAMTS13 deficiency. We report the eradication of persistent ADAMTS13 inhibitory autoantibodies and restoration of normal ADAMTS13 activity using the anti-CD38 antibody daratumumab in two patients with iTTP. One patient had a frequently relapsing course, and the other a treatment-refractory first episode. There were no relevant adverse drug reactions.

Strong, Nonresonant Radiation Enhances Cis-Trans Photoisomerization of Stilbene in Solution.

Previously, it has been demonstrated that external electric fields may be used to exert control over chemical reactivity. In this study, the impact of a strong, nonresonant IR field (1064 nm) on the photoisomerization of cis-stilbene is investigated in cyclohexane solution. The design of a suitable reaction vessel for characterization of this effect is presented. The electric field supplied by the pulsed, near-IR radiation (εl = 4.5 × 107 V/cm) enhances the cis → trans photoisomerization yield at the red edge of the absorption spectrum (wavelengths between 337 and 340 nm). Within the microliter focal volume, up to 75% of all cis-stilbene molecules undergo isomerization to trans-stilbene in the strong electric-field environment, indicating a significant increase relative to the 35% yield of trans-stilbene under field-free conditions. This result correlates with a 1-3% enhancement in the trans-stilbene concentration throughout the bulk solution. Theoretical analysis suggests that the observed change is the result of dynamic Stark shifting of the ground and first excited states, leading to a significant redshift in cis-stilbene's absorption spectrum. The predicted increase in the absorption cross section in this range of excitation wavelengths is qualitatively consistent with the experimental increase in trans-stilbene production.

Identification and regulation of a molecular module for bleb-based cell motility.

Single-cell migration is a key process in development, homeostasis, and disease. Nevertheless, the control over basic cellular mechanisms directing cells into motile behavior in vivo is largely unknown. Here, we report on the identification of a minimal set of parameters the regulation of which confers proper morphology and cell motility. Zebrafish primordial germ cells rendered immotile by knockdown of Dead end, a negative regulator of miRNA function, were used as a platform for identifying processes restoring motility. We have defined myosin contractility, cell adhesion, and cortex properties as factors whose proper regulation is sufficient for restoring cell migration of this cell type. Tight control over the level of these cellular features, achieved through a balance between miRNA-430 function and the action of the RNA-binding protein Dead end, effectively transforms immotile primordial germ cells into polarized cells that actively migrate relative to cells in their environment.