R1205H (Vicenza) causes conformational changes in the VWF-D'D3 domains and enhances VWF binding to clearance receptors LRP1 and SR-A1.

INTRODUCTION: Von Willebrand factor (VWF)-R1205H variant (Vicenza) results in markedly enhanced VWF clearance in humans that has been shown to be largely macrophage-mediated. However, the biological mechanisms underlying this enhanced clearance remain poorly understood. This study aimed to investigate the roles of (i) specific VWF domains and (ii) different macrophage receptors in regulating enhanced VWF-R1205H clearance. METHODS: In vivo clearance of full-length and truncated wild-type (WT)-VWF and VWF with R1205 substitutions was investigated in VWF-/- mice. Plate-binding assays were employed to characterize VWF binding to purified scavenger receptor class A member 1 (SR-A1), low-density lipoprotein receptor-related protein-1 (LRP1) cluster II or cluster IV receptors, and macrophage galactose-type lectin (MGL). RESULTS: In full-length VWF missing the A1 domain (VWF-ΔA1), introduction of R1205H led to significantly enhanced clearance in VWF-/- mice compared to WT-VWF-ΔA1. Importantly, R1205H in a truncated VWF-D'D3 fragment also triggered increased clearance compared to WT-VWF-D'D3. Additional in vivo studies demonstrated that VWF-R1205K (which preserves the positive charge at 1205) exhibited normal clearance, whereas VWF-R1205E (which results in loss of the positive charge) caused significantly enhanced clearance, pinpointing the importance of the positive charge at VWF-R1205. In vitro plate-binding studies confirmed increased VWF-R1205H interaction with SR-A1 compared to WT-VWF. Furthermore, significantly enhanced VWF-R1205H binding to LRP1 cluster IV (p<0.001) and less marked enhanced binding to LRP1 cluster II (p=0.034) was observed. In contrast, VWF-R1205H and WT-VWF demonstrated no difference in binding affinity to MGL. CONCLUSION: Disruption of the positive charge at amino acid 1205 causes conformational changes in the VWF-D'D3 domains, and triggers enhanced LRP1 and SR-A1 mediated clearance.

Low resilience is associated with worse health-related quality of life in caregivers of service members and veterans with traumatic brain injury: a longitudinal study.

PURPOSE: To examine [a] the association of caregiver health-related quality of life (HRQOL) and service member/veteran (SMV) neurobehavioral outcomes with caregiver resilience; [b] longitudinal change in resilience at the group and individual level; and [c] the magnitude of change at the individual level. METHODS: Caregivers (N = 232) of SMVs with traumatic brain injury completed a resilience measure, and 18 caregiver HRQOL and SMV neurobehavioral outcome measures at a baseline evaluation and follow-up evaluation three years later. Caregivers were divided into two resilience groups at baseline and follow-up: [1] Low Resilience (≤ 45 T, baseline n = 99, follow-up n = 93) and [2] High Resilience (> 45 T, baseline n = 133, follow-up n = 139). RESULTS: At baseline and follow-up, significant effects were found between Low and High Resilience groups for the majority of outcome measures. There were no significant differences in resilience from baseline to follow-up at the group-mean level. At the individual level, caregivers were classified into four longitudinal resilience groups: [1] Persistently Low Resilience (Baseline + Follow-up = Low Resilience, n = 60), [2] Reduced Resilience (Baseline = High Resilience + Follow-up = Low Resilience, n = 33), [3] Improved Resilience (Baseline = Low Resilience + Follow-up = High Resilience, n = 39), and [4] Persistently High Resilience (Baseline + Follow-up = High Resilience, n = 100). From baseline to follow-up, approximately a third of the Reduced and Improved Resilience groups reported a meaningful change in resilience (≥ 10 T). Nearly all of the Persistently High and Persistently Low Resilience groups did not report meaningful change in resilience (< 10 T). CONCLUSION: Resilience was not a fixed state for all caregivers. Early intervention may stall the negative caregiving stress-health trajectory and improve caregiver resilience.

Family caregivers of service members in United States Department of Defense health care report impairment in longitudinal health outcomes.

OBJECTIVE: To examine elevated symptoms on health-related quality of life (HRQOL) measures over 2 years in caregivers of service members with traumatic brain injury (TBI). To compare outcomes to caregivers of veterans. METHOD: Caregivers (N = 315) were classified into two groups: (a) service member caregiver group (n = 55) and (b) veteran caregiver group (n = 260). Caregivers completed 17 HRQOL measures at a baseline evaluation and follow-up evaluation 24 months later. RESULTS: In the service member caregiver group, the highest frequency of clinically elevated T-scores (≥ 60 T) at baseline and follow-up were found on physical and psychological HRQOL measures (16.4%-30.9%). A higher proportion of the veteran caregiver group had clinically elevated scores on nine measures at baseline and seven measures at follow-up. Examining the number of clinically elevated scores simultaneously across all 17 measures, the service member caregiver group had multiple elevated scores (e.g., 4 or more: baseline = 25.5%, follow-up = 27.3%). A higher proportion of the veteran caregiver group had multiple clinically elevated scores for 13 comparisons at baseline (h = .35-.82), but reduced to eight comparisons at follow-up (h = .36-.63). In the service member caregiver group, the proportion of caregivers with clinically elevated scores at baseline and follow-up was equally dispersed across persistent and newly developed symptoms, but higher for persistent symptoms compared to developed symptoms in the veteran caregiver group. CONCLUSIONS: Many caregivers of service members reported clinically elevated scores across HRQOL domains and the prevalence increased over 2 years. More services for caregivers in the Department of Defense may be helpful in reducing the trajectory of newly developed symptoms long term. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Longitudinal health-related quality of life in military caregivers no longer providing care.

PURPOSE/OBJECTIVE: To examine health-related quality of life (HRQOL) in caregivers when providing care and no longer providing care to service members/veterans with traumatic brain injury. RESEARCH METHOD/DESIGN: Participants included 466 caregivers enrolled in a 15-year longitudinal study. During an annual follow-up evaluation, a subsample of caregivers self-identified as no longer providing care and were retained in the study as a No Longer Caregiving group (n = 48). Scores on HRQOL measures when providing care (baseline) and no longer providing care (follow-up) were examined. Scores on HRQOL measures were also compared with the remaining 418 caregivers (Caregiving group). RESULTS: The most frequent reasons for no longer caregiving were no longer being in a relationship with the SMV and the SMV had recovered/no longer required care. The No Longer Caregiving group at follow-up reported better scores on five measures compared to baseline, and three measures compared to the Caregiving group. There were no differences in the proportion of clinically elevated scores on HRQOL measures for the No Longer Caregiving group between baseline and follow-up. Compared to the Caregiving group, the No Longer Caregiving group reported a higher prevalence of clinical elevated scores on General Life Satisfaction at baseline and follow-up, and worse scores on Caregiving Relationship Satisfaction and the Couples Satisfaction Index at baseline. CONCLUSIONS/IMPLICATIONS: While some improvement in HRQOL was noted when caregivers were no longer providing care, many continued to report elevated scores. Services and supports are required for caregivers when providing care, but also when transitioning out of a caregiving role. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Health outcomes in caregivers of service members and veterans with traumatic brain injury enrolled in the U.S. Veterans Affairs Caregiver Support Program.

To explore health outcomes in caregivers of service members and veterans (SMV) with traumatic brain injury (TBI) enrolled in two programs within the U.S. Department of Veterans Affairs (VA) Caregiver Support Program (CSP) (General and Comprehensive Programs) and those not enrolled. Participants were 290 caregivers classified into three groups: (a) General Program (n = 34); (b) Comprehensive Program (n = 104); and (c) Not Enrolled (n = 152). Main outcome measures assessed caregiver health-related quality of life (HRQOL), SMV functional ability, and caregiver needs. Compared to the Not Enrolled group, the General, and Comprehensive Program groups reported worse scores on five of 25 caregiver HRQOL measures and had a higher proportion of elevated scores on two measures. The Comprehensive Program group reported worse scores on an additional seven HRQOL measures and a higher proportion of elevated scores on three measures compared to the Not Enrolled group. Over 20% of caregivers in each group reported clinically elevated scores on eight HRQOL measures. Few differences between caregiver groups were identified for unmet needs. In the total sample, eight HRQOL measures consistently emerged that were more strongly associated with caregiver needs. Caregivers enrolled in the VA CSP tended to report worse HRQOL and caring for a SMV with worse functional ability compared to those not enrolled. A better understanding of health care utilization for those not enrolled in the CSP and in need of help is required. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

A Hybrid Effectiveness/Implementation Clinical Trial of Adherence to Long-Term Oxygen Therapy for Chronic Obstructive Pulmonary Disease.

Rationale: Interventions to promote adherence to long-term oxygen therapy (LTOT) in chronic obstructive pulmonary disease (COPD) are needed. Objectives: To examine the real-world effectiveness of phone-based peer coaching on LTOT adherence and other outcomes in a pragmatic trial of patients with COPD. Methods: In a hybrid effectiveness/implementation pragmatic trial, patients were randomized to receive phone-based proactive coaching (educational materials, five phone-based peer coaching sessions over 60 d), reactive coaching (educational materials, peer coaching when requested), or usual care. Study staff members collected baseline and outcome data via phone at 30, 60, and 90 days after randomization. Adherence to LTOT over 60 days, the primary effectiveness outcome, was defined as mean LTOT use ⩾17.7 h/d. LTOT use was calculated using information about home oxygen equipment use in worksheets completed by study participants. Comparisons of adherence to LTOT between each coaching group and the usual care group using multivariable logistic regression models were prespecified as the primary analyses. Secondary effectiveness outcomes included Patient Reported Outcome Management Information System measures for physical, emotional, and social health. We assessed early implementation domains in the reach, adoption, and implementation framework. Results: In 444 participants, the proportions who were adherent to LTOT at 60 days were 74% in usual care, 84% in reactive coaching, and 70% in proactive coaching groups. Although reach, adoption by stakeholder partners, and intervention fidelity were acceptable, complete LTOT adherence data were available in only 73% of participants. Reactive coaching (adjusted odds ratio, 1.77; 97.5% confidence interval, 0.80-3.90) and proactive coaching (adjusted odds ratio, 0.70; 97.5% confidence interval, 0.34-1.46) did not improve adherence to LTOT compared with usual care. However, proactive coaching significantly reduced depressive symptoms and sleep disturbance compared with usual care and reduced depressive symptoms compared with reactive coaching. Unexpectedly, LTOT adherence was significantly lower in the proactive compared with the reactive coaching group. Conclusions: The results were inconclusive about whether a phone-based peer coaching strategy changed LTOT adherence compared with usual care. Further studies are needed to confirm the potential benefits of proactive peer coaching on secondary effectiveness outcomes and differences in LTOT adherence between proactive and reactive peer coaching. Clinical trial registered with ClinicalTrials.gov (NCT02098369).

Health outcomes before and during the COVID-19 pandemic in caregivers of service members and veterans with traumatic brain injury.

PURPOSE: To examine change in health-related quality of life (HRQOL) during the COVID-19 pandemic in caregivers of service members/veterans (SMVs) with traumatic brain injury (TBI), by comparing HRQOL during the first year of the pandemic to HRQOL 12 months pre-pandemic. METHODS: Caregivers (N = 246) were classified into three COVID-19 Pandemic Impact groups based on impact ratings of the pandemic on HRQOL: No Impact (n = 50), Mild Impact (n = 117), and Moderate-Severe Impact (n = 79). Caregivers completed 19 measures across physical, social, caregiving, and economic HRQOL domains, and a measure of SMV Adjustment. T-scores were used to determine individual symptom trajectories for each measure as follows: Asymptomatic (pre + during < 60 T); Developed (pre < 60 + during ≥ 60 T); Improved (pre ≥ 60 T + during < 60 T); and Persistent (pre + during ≥ 60 T). RESULTS: Using ANOVA, during the pandemic, the Moderate-Severe Impact group reported worse scores on 19 measures (d = 0.41-0.89) compared to the No Impact group and 18 measures (d = 0.31-0.62) compared to the Mild Impact group (d = 0.31-0.38). The Mild Impact group reported worse scores on two measures compared to the No Impact group (d = 0.42-0.43). Using the entire sample, the majority of HRQOL measures were classified as Asymptomatic (47.2-94.7%), followed by Persistent (2.4-27.2%). Few were classified as Developed (0.4-12.6%) or Improved (2.4-13.8%). Using repeated measures ANOVA, no meaningful effects sizes were found for mean scores on all measures completed pre-pandemic compared to during the pandemic (d ≤ 0.17). CONCLUSION: The vast majority of caregivers reported stability in HRQOL pre-pandemic compared to during the pandemic. The COVID-19 pandemic was not associated with a high prevalence of decline in caregiver HRQOL.

Von Willebrand Disease: Gaining a global perspective.

INTRODUCTION: Recent guidelines for von Willebrand Disease (VWD) highlighted the challenges in diagnosis and management. Identifying the number of persons with VWD (PwVWD) internationally will help target support to aid diagnosis of PwVWD. AIM: To examine international registration rates of PwVWD, the influence of income status, geographical region and the age and sex profile. Cumulatively, these data will be used to inform future strategy from the World Federation of Haemophilia (WFH) to address unmet clinical and research needs. METHODS: Data from the 2018/2019 WFH Annual Global Survey (AGS) were analysed, providing a global perspective on VWD registration. RESULTS: Registration rates are lowest in South Asia (0.6/million population) and highest in Europe/Central Asia (50.9/million population, 0.005%), but below the expected prevalence rate (0.1%). National economic status impacted VWD registration rates, reflecting variation in access to optimal healthcare infrastructure. Females represented the majority of PwVWD globally, however, in low-income countries (LIC) males predominated. Age profile varied, with markedly higher rates of paediatric registrations in North America, Middle East and North Africa and South Asia. Rates of type 3 VWD registrations were significantly influenced by economic status (81% of VWD diagnoses in LIC), suggesting only the most severe VWD types are diagnosed in resource limited settings. CONCLUSION: Significant variation in registration rates of PwVWD exist internationally and is influenced by income status and the presence of HTC networks. Improved understanding of registration rates will enable targeting of advocacy to improve awareness, diagnosis and support for PwVWD internationally. KEY POINTS: Registration rates of People with Von Willebrand Disease (PwVWD) vary internationally and are influenced by national income status Although females represent the majority of PwVWD globally, in low income countries (LIC) males predominated, possibly related to stigma surrounding gynaecological bleeding. Rates of type 3 VWD registration were significantly influenced by economic status (81% of VWD diagnoses in LIC), suggesting only the most severe VWD types are diagnosed in resource limited settings.

Macrophage Galactose Lectin Contributes to the Regulation of FVIII (Factor VIII) Clearance in Mice-Brief Report.

BACKGROUND: Although most plasma FVIII (Factor VIII) circulates in complex with VWF (von Willebrand factor), a minority (3%-5%) circulates as free-FVIII, which is rapidly cleared. Consequently, 20% of total FVIII may be cleared as free-FVIII. Critically, the mechanisms of free-FVIII clearance remain poorly understood. However, recent studies have implicated the MGL (macrophage galactose lectin) in modulating VWF clearance. METHODS: Since VWF and FVIII share similar glycosylation, we investigated the role of MGL in FVIII clearance. FVIII binding to MGL was assessed in immunosorbent and cell-based assays. In vivo, FVIII clearance was assessed in MGL1-/- and VWF-/-/FVIII-/- mice. RESULTS: In vitro-binding studies identified MGL as a novel macrophage receptor that binds free-FVIII in a glycan-dependent manner. MGL1-/- and MGL1-/- mice who received an anti-MGL1/2 blocking antibody both showed significantly increased endogenous FVIII activity compared with wild-type mice (P=0.036 and P<0.0001, respectively). MGL inhibition also prolonged the half-life of infused FVIII in FVIII-/- mice. To assess whether MGL plays a role in the clearance of free FVIII in a VWF-independent manner, in vivo clearance experiments were repeated in dual VWF-/-/FVIII-/- mice. Importantly, the rapid clearance of free FVIII in VWF-/-/FVIII-/- mice was significantly (P=0.012) prolonged in the presence of anti-MGL1/2 antibodies. Finally, endogenous plasma FVIII levels in VWF-/- mice were significantly increased following MGL inhibition (P=0.016). CONCLUSIONS: Cumulatively, these findings demonstrate that MGL plays an important role in regulating macrophage-mediated clearance of both VWF-bound FVIII and free-FVIII in vivo. We propose that this novel FVIII clearance pathway may be of particular clinical importance in patients with type 2N or type 3 Von Willebrand disease.

Endothelial cell activation, Weibel-Palade body secretion, and enhanced angiogenesis in severe COVID-19.

Background: Severe COVID-19 is associated with marked endothelial cell (EC) activation that plays a key role in immunothrombosis and pulmonary microvascular occlusion. However, the biological mechanisms through which SARS-CoV-2 causes EC activation and damage remain poorly defined. Objectives: We investigated EC activation in patients with acute COVID-19, and specifically focused on how proteins stored within Weibel-Palade bodies may impact key aspects of disease pathogenesis. Methods: Thirty-nine patients with confirmed COVID-19 were recruited. Weibel-Palade body biomarkers (von Willebrand factor [VWF], angiopoietin-2 [Angpt-2], and osteoprotegerin) and soluble thrombomodulin (sTM) levels were determined. In addition, EC activation and angiogenesis were assessed in the presence or absence of COVID-19 plasma incubation. Results: Markedly elevated plasma VWF antigen, Angpt-2, osteoprotegerin, and sTM levels were observed in patients with acute COVID-19. The increased levels of both sTM and Weibel-Palade body components (VWF, osteoprotegerin, and Angpt-2) correlated with COVID-19 severity. Incubation of COVID-19 plasma with ECs triggered enhanced VWF secretion and increased Angpt-2 expression, as well as significantly enhanced in vitro EC tube formation and angiogenesis. Conclusion: We propose that acute SARS-CoV-2 infection leads to a complex and multifactorial EC activation, progressive loss of thrombomodulin, and increased Angpt-2 expression, which collectively serve to promote a local proangiogenic state.

Enhanced VWF clearance in low VWF pathogenesis: limitations of the VWFpp/VWF:Ag ratio and clinical significance.

Increased von Willebrand factor (VWF) clearance plays a key role in the pathogenesis of type 1 and type 2 von Willebrand disease (VWD). However, the pathological mechanisms involved in patients with mild to moderate reductions in plasma VWF:Ag (range, 30-50 IU/dL; low VWF) remain poorly understood. In this study, we investigated the hypothesis that enhanced VWF clearance may contribute to the pathobiology of low VWF. Patients with low VWF were recruited to the LoVIC study after ethics approval and receipt of informed consent. Desmopressin was administered IV in 75 patients, and blood samples were drawn at baseline and at the 1-hour and 4-hour time points. As defined by recent ASH/ISTH/NHF/WFH guidelines, 20% of our low-VWF cohort demonstrated significantly enhanced VWF clearance. Importantly, from a clinical perspective, this enhanced VWF clearance was seen after desmopressin infusion, but did not affect the steady-state VWF propeptide (VWFpp)-to-VWF antigen (VWF:Ag) ratio (VWFpp/VWF:Ag) in most cases. The discrepancy between the VWFpp/VWF:Ag ratio and desmopressin fall-off rates in patients with mild quantitative VWD may have reflected alteration in VWFpp clearance kinetics. Finally, bleeding scores were significantly lower in patients with low VWF with enhanced VWF clearance, compared with those in whom reduced VWF biosynthesis represented the principle pathogenic mechanism. This trial was registered at http://www.clinicaltrials.gov as #NCT03167320.

von Willebrand factor links primary hemostasis to innate immunity.

The plasma multimeric glycoprotein von Willebrand factor (VWF) plays a critical role in primary hemostasis by tethering platelets to exposed collagen at sites of vascular injury. Recent studies have identified additional biological roles for VWF, and in particular suggest that VWF may play an important role in regulating inflammatory responses. However, the molecular mechanisms through which VWF exerts its immuno-modulatory effects remain poorly understood. In this study, we report that VWF binding to macrophages triggers downstream MAP kinase signaling, NF-κB activation and production of pro-inflammatory cytokines and chemokines. In addition, VWF binding also drives macrophage M1 polarization and shifts macrophage metabolism towards glycolysis in a p38-dependent manner. Cumulatively, our findings define an important biological role for VWF in modulating macrophage function, and thereby establish a novel link between primary hemostasis and innate immunity.

Caregiver sleep impairment and service member and veteran adjustment following traumatic brain injury is related to caregiver health-related quality of life.

STUDY OBJECTIVES: To examine the relationship between caregiver sleep impairment and/or service member/veteran (SMV) adjustment post-traumatic brain injury, with caregiver health-related quality of life (HRQOL). METHODS: Caregivers (n = 283) completed 18 measures of HRQOL, sleep impairment, and SMV adjustment. Caregivers were classified into 4 sleep impairment/SMV adjustment groups: 1) Good Sleep/Good Adjustment (n = 43), 2) Good Sleep/Poor Adjustment (n = 39), 3) Poor Sleep/Good Adjustment (n = 55), and 4) Poor Sleep/Poor Adjustment (n = 146). RESULTS: The Poor Sleep/Poor Adjustment group reported significantly worse scores on most HRQOL measures and a higher prevalence of clinically elevated T-scores (≥ 60T) on the majority of comparisons compared to the other 3 groups. The Good Sleep/Poor Adjustment and Poor Sleep/Good Adjustment groups reported worse scores on the majority of the HRQOL measures and a higher prevalence of clinically elevated scores on 7 comparisons compared to the Good Sleep/Good Adjustment group. Fewer differences were found between the Good Sleep/Poor Adjustment and Poor Sleep/Good Adjustment groups. The Poor Sleep/Poor Adjustment group reported a higher prevalence of severe ratings for SMV Irritability, Anger, and Aggression compared to the Good Sleep/Poor Adjustment group. CONCLUSIONS: While the presence of either caregiver sleep impairment or poor SMV adjustment singularly was associated with worse caregiver HRQOL, the presence of both sleep impairment and poor SMV adjustment was associated with further impairment in HRQOL. Caregivers could benefit from sleep intervention. Treatment of SMVs neurobehavioral problems may improve the SMV's recovery and lessen sleep problems, distress, and burden among their caregivers. CITATION: Brickell TA, Wright MM, Sullivan JK, et al. Caregiver sleep impairment and service member and veteran adjustment following traumatic brain injury is related to caregiver health-related quality of life. J Clin Sleep Med. 2022;18(11):2577-2588.

Effect of Two Interventional Strategies on Improving Continuous Positive Airway Pressure Adherence in Existing COPD and Obstructive Sleep Apnea Patients: The O2VERLAP Study.

Background: Obstructive sleep apnea (OSA) is a sleep disorder prevalent in >10% of individuals diagnosed with chronic obstructive pulmonary disease (COPD). Continuous positive airway pressure (CPAP) is the first-line therapy for OSA, but many do not use it enough during sleep to effectively manage OSA. The O2VERLAP study compared proactive care (PC)-structured web-based peer-coaching education and support intervention versus reactive care (RC)-education and support based on limited scheduled interactions and patient-initiated contacts. Methods: Participants were primarily recruited from patient communities (COPD, OSA, and the National Patient-Centered Outcomes Research Network [PCORnet]) through electronic methods. Inclusion criteria: ≥40 years old, diagnosis of both COPD and OSA, and currently using CPAP. Participants were then randomly assigned to either the PC or RC group, with outcomes assessed at baseline and 6 and 12 weeks. The primary study outcome was CPAP adherence (hours of use/night) and secondary outcomes were daytime functioning, sleep quality, and daytime sleepiness. Changes in outcomes over time were examined using random effects models. Results: The study enrolled 332 participants of which 294 were randomized. While groups differed significantly in CPAP adherence at baseline (PC: 6.1±3.1, RC: 7.3±2.4 hours/night; P<0.001), there were no significant differences in change of primary and secondary outcomes at either 6 or 12 weeks. Conclusion: In this group of patients with both COPD and OSA on CPAP therapy, no difference was found between the provision of PC and RC. The study did find unexpectedly high baseline CPAP adherence levels, which suggests that any improvement from the intervention would have been very small and difficult to detect.

Sustained VWF-ADAMTS-13 axis imbalance and endotheliopathy in long COVID syndrome is related to immune dysfunction.

BACKGROUND: Prolonged recovery is common after acute SARS-CoV-2 infection; however, the pathophysiological mechanisms underpinning Long COVID syndrome remain unknown. VWF/ADAMTS-13 imbalance, dysregulated angiogenesis, and immunothrombosis are hallmarks of acute COVID-19. We hypothesized that VWF/ADAMTS-13 imbalance persists in convalescence together with endothelial cell (EC) activation and angiogenic disturbance. Additionally, we postulate that ongoing immune cell dysfunction may be linked to sustained EC and coagulation activation. PATIENTS AND METHODS: Fifty patients were reviewed at a minimum of 6 weeks following acute COVID-19. ADAMTS-13, Weibel Palade Body (WPB) proteins, and angiogenesis-related proteins were assessed and clinical evaluation and immunophenotyping performed. Comparisons were made with healthy controls (n = 20) and acute COVID-19 patients (n = 36). RESULTS: ADAMTS-13 levels were reduced (p = 0.009) and the VWF-ADAMTS-13 ratio was increased in convalescence (p = 0.0004). Levels of platelet factor 4 (PF4), a putative protector of VWF, were also elevated (p = 0.0001). A non-significant increase in WPB proteins Angiopoietin-2 (Ang-2) and Osteoprotegerin (OPG) was observed in convalescent patients and WPB markers correlated with EC parameters. Enhanced expression of 21 angiogenesis-related proteins was observed in convalescent COVID-19. Finally, immunophenotyping revealed significantly elevated intermediate monocytes and activated CD4+ and CD8+ T cells in convalescence, which correlated with thrombin generation and endotheliopathy markers, respectively. CONCLUSION: Our data provide insights into sustained EC activation, dysregulated angiogenesis, and VWF/ADAMTS-13 axis imbalance in convalescent COVID-19. In keeping with the pivotal role of immunothrombosis in acute COVID-19, our findings support the hypothesis that abnormal T cell and monocyte populations may be important in the context of persistent EC activation and hemostatic dysfunction during convalescence.

The role of VWF/FVIII in thrombosis and cancer progression in multiple myeloma and other hematological malignancies.

Cancer associated thrombosis (CAT) is associated with significant morbidity and mortality, highlighting an unmet clinical need to improve understanding of the pathophysiology of CAT. Multiple myeloma (MM) is associated with one of the highest rates of thrombosis despite widespread use of thromboprophylactic agents. The pathophysiology of thrombosis in MM is multifactorial and patients with MM appear to display a hypercoagulable phenotype with potential contributory factors including raised von Willebrand factor (VWF) levels, activated protein C resistance, impaired fibrinolysis, and abnormal thrombin generation. In addition, the toxic effect of anti-myeloma therapies on the endothelium and contribution to thrombosis has been widely described. Elevated VWF/factor VIII (FVIII) plasma levels have been reported in heterogeneous cohorts of patients with MM and other hematological malignancies. In specific studies, high plasma VWF levels have been shown to associate with VTE risk and reduced overall survival. While the mechanisms underpinning this remain unclear, dysregulation of the VWF and A Disintegrin And Metalloprotease Thrombospondin type 1, motif 13 (ADAMTS-13) axis is evident in certain solid organ malignancies and correlates with advanced disease and thrombosis. Furthermore, thrombotic microangiopathic conditions arising from deficiencies in ADAMTS-13 and thus an accumulation of prothrombotic VWF multimers have been reported in patients with MM, particularly in association with specific myeloma therapies. This review will discuss current evidence on the pathophysiological mechanisms underpinning thrombosis in MM and in particular summarize the role of VWF/FVIII in hematological malignancies with a focus on thrombotic risk and emerging evidence for contribution to disease progression.

Breast cancer cells mediate endothelial cell activation, promoting von Willebrand factor release, tumor adhesion, and transendothelial migration.

BACKGROUND: Breast cancer results in a three- to four-fold increased risk of venous thromboembolism (VTE), which is associated with reduced patient survival. Despite this, the mechanisms underpinning breast cancer-associated thrombosis remain poorly defined. Tumor cells can trigger endothelial cell (EC) activation resulting in increased von Willebrand factor (VWF) secretion. Importantly, elevated plasma VWF levels constitute an independent biomarker for VTE risk. Moreover, in a model of melanoma, treatment with low molecular weight heparin (LMWH) negatively regulated VWF secretion and attenuated tumor metastasis. OBJECTIVE: To investigate the role of VWF in breast cancer metastasis and examine the effect of LMWH in modulating EC activation and breast tumor transmigration. METHODS: von Willebrand factor levels were measured by ELISA. Primary ECs were used to assess tumor-induced activation, angiogenesis, tumor adhesion, and transendothelial migration. RESULTS AND CONCLUSION: Patients with metastatic breast cancer have markedly elevated plasma VWF:Ag levels that also correlate with poorer survival. MDA-MB-231 and MCF-7 breast cancer cells induce secretion of VWF, angiopoietin-2, and osteoprotegerin from ECs, which is further enhanced by the presence of platelets. Vascular endothelial growth factor-A (VEGF-A) plays an important role in modulating breast cancer-induced VWF release. Moreover, VEGF-A from breast tumor cells also contributes to a pro-angiogenic effect on ECs. VWF multimers secreted from ECs, in response to tumor-VEGF-A, mediate adhesion of breast tumor cells along the endothelium. LMWH inhibits VWF-breast tumor adhesion and transendothelial migration. Our findings highlight the significant crosstalk between tumor cells and the endothelium including increased VWF secretion which may contribute to tumor metastasis.

Potential mechanisms of resistance to current anti-thrombotic strategies in Multiple Myeloma.

Multiple Myeloma (MM) is a common haematological malignancy that is associated with a high rate of venous thromboembolism (VTE) with almost 10% of patients suffering thrombosis during their disease course. Recent studies have shown that, despite current thromboprophylaxis strategies, VTE rates in MM remain disappointingly high. The pathophysiology behind this consistently high rate of VTE is likely multifactorial. A number of factors such as anti-thrombin deficiency or raised coagulation Factor VIII levels may confer resistance to heparin in these patients, however, the optimal method of clinically evaluating this is unclear at present, though some groups have attempted its characterisation with thrombin generation testing (TGT). In addition to testing for heparin resistance, TGT in patients with MM has shown markedly varied abnormalities in both endogenous thrombin potential and serum thrombomodulin levels. Apart from these thrombin-mediated processes, other mechanisms potentially contributing to thromboprophylaxis failure include activated protein C resistance, endothelial toxicity secondary to chemotherapy agents, tissue factor abnormalities and the effect of immunoglobulins/"M-proteins" on both the endothelium and on fibrin fibre polymerisation. It thus appears clear that there are a multitude of factors contributing to the prothrombotic milieu seen in MM and further work is necessitated to elucidate which factors may directly affect and inhibit response to anticoagulation and which factors are contributing in a broader fashion to the hypercoagulability phenotype observed in these patients so that effective thromboprophylaxis strategies can be employed.