Soluble Glycoprotein VI Predicts Abdominal Aortic Aneurysm Growth Rate and is a Novel Therapeutic Target.

A common feature in patients with abdominal aortic aneurysms (AAA) is the formation of a nonocclusive intraluminal thrombus (ILT) in regions of aortic dilation. Platelets are known to maintain hemostasis and propagate thrombosis through several redundant activation mechanisms, yet the role of platelet activation in the pathogenesis of AAA associated ILT is still poorly understood. Thus, we sought to investigate how platelet activation impacts the pathogenesis of AAA. Using RNA-sequencing, we identify that the platelet-associated transcripts are significantly enriched in the ILT compared to the adjacent aneurysm wall and healthy control aortas. We found that the platelet specific receptor glycoprotein VI (GPVI) is among the top enriched genes in AAA ILT and is increased on the platelet surface of AAA patients. Examination of a specific indicator of platelet activity, soluble GPVI (sGPVI), in two independent AAA patient cohorts is highly predictive of a AAA diagnosis and associates more strongly with aneurysm growth rate when compared to D-dimer in humans. Finally, intervention with the anti-GPVI antibody (JAQ1) in mice with established aneurysms blunted the progression of AAA in two independent mouse models. In conclusion, we show that levels of sGPVI in humans can predict a diagnosis of AAA and AAA growth rate, which may be critical in the identification of high-risk patients. We also identify GPVI as a novel platelet-specific AAA therapeutic target, with minimal risk of adverse bleeding complications, where none currently exist.

Platelets at the Vessel Wall in Non-Thrombotic Disease.

Platelets are small, anucleate entities that bud from megakaryocytes in the bone marrow. Among circulating cells, platelets are the most abundant cell, traditionally involved in regulating the balance between thrombosis (the terminal event of platelet activation) and hemostasis (a protective response to tissue injury). Although platelets lack the precise cellular control offered by nucleate cells, they are in fact very dynamic cells, enriched in preformed RNA that allows them the capability of de novo protein synthesis which alters the platelet phenotype and responses in physiological and pathological events. Antiplatelet medications have significantly reduced the morbidity and mortality for patients afflicted with thrombotic diseases, including stroke and myocardial infarction. However, it has become apparent in the last few years that platelets play a critical role beyond thrombosis and hemostasis. For example, platelet-derived proteins by constitutive and regulated exocytosis can be found in the plasma and may educate distant tissue including blood vessels. First, platelets are enriched in inflammatory and anti-inflammatory molecules that may regulate vascular remodeling. Second, platelet-derived microparticles released into the circulation can be acquired by vascular endothelial cells through the process of endocytosis. Third, platelets are highly enriched in mitochondria that may contribute to the local reactive oxygen species pool and remodel phospholipids in the plasma membrane of blood vessels. Lastly, platelets are enriched in proteins and phosphoproteins which can be secreted independent of stimulation by surface receptor agonists in conditions of disturbed blood flow. This so-called biomechanical platelet activation occurs in regions of pathologically narrowed (atherosclerotic) or dilated (aneurysmal) vessels. Emerging evidence suggests platelets may regulate the process of angiogenesis and blood flow to tumors as well as education of distant organs for the purposes of allograft health following transplantation. This review will illustrate the potential of platelets to remodel blood vessels in various diseases with a focus on the aforementioned mechanisms.

Venous thromboembolic outcomes in patients with lymphedema and lipedema: An analysis from the National Inpatient Sample.

BACKGROUND: Patients with lymphedema and lipedema share physical exam findings that may lead to misdiagnosis. Poor mobility is common in patients with obesity and patients with lymphedema and lipedema. This may constitute a risk factor for venous thromboembolism (VTE). Our objective was to evaluate the association of VTE in obese patients with lymphedema and lipedema. METHODS: The National Inpatient Sample (NIS) was searched from 2016 to 2020 to identify hospital admissions of obese female patients with lymphedema and lipedema. Patients were analyzed in the context of presence or absence of VTE while adjusting for complex cluster sampling techniques. Predictors of VTE were accessed by multivariable regression. RESULTS: Lymphedema was identified in 189,985 patients and lipedema in 50,645 patients. VTE was observed in 3.12% (n = 374,210) of patients with obesity. In patients with obesity, VTE was more common in patients with lymphedema than without (2.6% vs 1.6%; p < 0.01). Similarly, VTE was more common in patients with lipedema than without (0.6% vs 0.4%; p < 0.01). After multivariable logistic regression, VTE events in obese patients with lymphedema were higher versus without (OR 1.6; CI 1.08-2.43; p = 0.02). Similarly, VTE events were more common in obese patients with lipedema versus obese patients without lipedema (OR 1.20; CI 1.03-1.41; p = 0.02). CONCLUSIONS: In this hypothesis-generating study, lymphedema and lipedema show a positive association with VTE after adjusting for baseline patient characteristics such as obesity, which is a known independent risk factor for VTE. Mechanisms whereby lymphedema and lipedema are associated with VTE should be investigated.

Dysregulated platelet function in patients with postacute sequelae of COVID-19.

BACKGROUND: Postacute sequelae of COVID-19 (PASC), also referred to as "Long COVID", sometimes follows COVID-19, a disease caused by SARS-CoV-2. Although SARS-CoV-2 is well known to promote a prothrombotic state, less is known about the thrombosis risk in PASC. Our objective was to evaluate platelet function and thrombotic potential in patients following recovery from SARS-CoV-2, but with clear symptoms of patients with PASC. METHODS: patients with PASC and matched healthy controls were enrolled in the study on average 15 months after documented SARS-CoV-2 infection. Platelet activation was evaluated by light transmission aggregometry (LTA) and flow cytometry in response to platelet surface receptor agonists. Thrombosis in platelet-deplete plasma was evaluated by Factor Xa activity. A microfluidics system assessed thrombosis in whole blood under shear stress conditions. RESULTS: A mild increase in platelet aggregation in patients with PASC through the thromboxane receptor was observed, and platelet activation through the glycoprotein VI (GPVI) receptor was decreased in patients with PASC compared to age- and sex-matched healthy controls. Thrombosis under shear conditions as well as Factor Xa activity were reduced in patients with PASC. Plasma from patients with PASC was an extremely potent activator of washed, healthy platelets - a phenomenon not observed when stimulating healthy platelets after incubation with plasma from healthy individuals. CONCLUSIONS: patients with PASC show dysregulated responses in platelets and coagulation in plasma, likely caused by a circulating molecule that promotes thrombosis. A hitherto undescribed protective response appears to exist in patients with PASC to counterbalance ongoing thrombosis that is common to SARS-CoV-2 infection.

Neisseria meningitidis Lacking the Major Porins PorA and PorB Is Viable and Modulates Apoptosis and the Oxidative Burst of Neutrophils.

The bacterial pathogen Neisseria meningitidis expresses two major outer-membrane porins. PorA expression is subject to phase-variation (high frequency, random, on-off switching), and both PorA and PorB are antigenically variable between strains. PorA expression is variable and not correlated with meningococcal colonisation or invasive disease, whereas all naturally-occurring strains express PorB suggesting strong selection for expression. We have generated N. meningitidis strains lacking expression of both major porins, demonstrating that they are dispensable for bacterial growth in vitro. The porAB mutant strain has an exponential growth rate similar to the parental strain, as do the single porA or porB mutants, but the porAB mutant strain does not reach the same cell density in stationary phase. Proteomic analysis suggests that the double mutant strain exhibits compensatory expression changes in proteins associated with cellular redox state, energy/nutrient metabolism, and membrane stability. On solid media, there is obvious growth impairment that is rescued by addition of blood or serum from mammalian species, particularly heme. These porin mutants are not impaired in their capacity to inhibit both staurosporine-induced apoptosis and a phorbol 12-myristate 13-acetate-induced oxidative burst in human neutrophils suggesting that the porins are not the only bacterial factors that can modulate these processes in host cells.

Dysregulated Platelet Function in Patients with Post-Acute Sequelae of COVID-19.

Background: Post-acute sequelae of COVID-19 (PASC), also referred as Long-COVID, sometimes follows COVID-19, a disease caused by SARS-CoV-2. While SARS-CoV-2 is well-known to promote a prothrombotic state, less is known about the thrombosis risk in PASC. Aim: Our objective was to evaluate the platelet function and thrombotic potential in patients following recovery from SARS-CoV-2 with clear symptoms of PASC. Methods: PASC patients and matched healthy controls were enrolled in the study on average 15 months after documented SARS-CoV-2 infection. Platelet activation was evaluated by Light Transmission Aggregometry (LTA) and flow cytometry in response to platelet surface receptor agonists. Thrombosis in platelet-deplete plasma was evaluated by Factor Xa activity. A microfluidics system assessed thrombosis in whole blood under shear stress conditions. Results: A mild increase in platelet aggregation in PASC patients through the thromboxane receptor was observed and platelet activation through the glycoprotein VI (GPVI) receptor was decreased in PASC patients compared to age- and sex-matched healthy controls. Thrombosis under shear conditions as well as Factor Xa activity were reduced in PASC patients. Plasma from PASC patients was an extremely potent activator of washed, healthy platelets - a phenomenon not observed when stimulating healthy platelets after incubation with plasma from healthy individuals. Conclusions: PASC patients show dysregulated responses in platelets and coagulation in plasma, likely caused by a circulating molecule that promotes thrombosis. A hitherto undescribed protective response appears to exists in PASC patients to counterbalance ongoing thrombosis that is common to SARS-CoV-2 infection.

Glycoprotein VI is Critical for the Detection and Progression of Abdominal Aortic Aneurysms.

A common feature in patients with abdominal aortic aneurysms (AAA) is the formation of a nonocclusive intraluminal thrombus (ILT) in regions of aortic dilation. Platelets are known to maintain hemostasis and propagate thrombosis through several redundant activation mechanisms, yet the role of platelet activation in the pathogenesis of AAA associated ILT is still poorly understood. Thus, we sought to investigate how platelet activation impacts the pathogenesis of AAA. Using RNA-sequencing, we identify that the platelet-associated transcripts are significantly enriched in the ILT compared to the adjacent aneurysm wall and healthy control aortas. We found that the platelet specific receptor glycoprotein VI (GPVI) is among the top enriched genes in AAA ILT and is increased on the platelet surface of AAA patients. Examination of a specific indicator of platelet activity, soluble GPVI (sGPVI), in two independent AAA patient cohorts is highly predictive of a AAA diagnosis and associates more strongly with aneurysm growth rate when compared to D-dimer in humans. Finally, intervention with the anti-GPVI antibody (J) in mice with established aneurysms blunted the progression of AAA in two independent mouse models. In conclusion, we show that levels of sGPVI in humans can predict a diagnosis of AAA and AAA growth rate, which may be critical in the identification of high-risk patients. We also identify GPVI as a novel platelet-specific AAA therapeutic target, with minimal risk of adverse bleeding complications, where none currently exist. KEY POINTS: Soluble glycoprotein VI, which is a platelet-derived blood biomarker, predicts a diagnosis of AAA, with high sensitivity and specificity in distinguishing patients with fast from slow-growing AAA.Blockade of glycoprotein VI in mice with established aneurysms reduces AAA progression and mortality, indicating therapeutic potential.

Tumor necrosis factor-alpha gene -308 G/A polymorphism modulates the relationship between dietary fat intake, serum lipids, and obesity risk in black South African women.

The prevalence of obesity and related disease risk is high in black South African (SA) women, possibly influenced by the dietary transition associated with urbanization. This study explored interactions between dietary fat intake and the tumor necrosis factor-alpha (TNFA) -308 G/A polymorphism on obesity, insulin resistance, and serum lipid concentrations in urbanized black SA women. Normal-weight (n = 105) and obese (n = 118) women underwent measurements of body composition, fat distribution, fasting serum lipids, glucose and insulin concentrations, and dietary intake. Participants were genotyped for the functional TNFA -308 G/A polymorphism. The genotype or allele frequency of the TNFA -308 G/A polymorphism did not differ between the BMI groups. However, when dietary fat intake was 30% of total energy intake [percentage energy (%E)], the odds of being obese with the TNFA GA+AA genotype was only 12% of that with GG, but increasing intake of dietary fat (%E) was associated with a significantly faster rate of increase in obesity risk in women with the TNFA GA+AA genotype compared with those with the GG genotype (P = 0.036). There were significant diet-gene interactions between alpha-linolenic acid (%E) and the total cholesterol:HDL-cholesterol ratio (P = 0.036), and PUFA (%E) and LDL cholesterol levels (P = 0.026), with participants with the A allele being more responsive to changes in relative fat intake. The TNFA -308 G/A polymorphism modified the relationship between dietary fat intake, obesity risk, and serum lipid concentrations in black SA women.

Comparison of body fatness measurements by near-infrared reactance and dual-energy X-ray absorptiometry in normal-weight and obese black and white women.

The aim of the present study was to compare body fat percent (BF %) using single-site near-IR reactance (NIR) and dual-energy X-ray absorptiometry (DXA) in a cohort of normal-weight (BMI < 25 kg/m2) black (n 102) and white (n 71); and obese (BMI > or = 30 kg/m2) black (n 117) and white (n 41) South African women (18-45 years). NIR-derived BF % was significantly correlated with DXA-derived BF % in all groups: normal-weight black (r 0.55, 95 % CI: 0.40, 0.67, P < 0.001) and white (r 0.69, 95 % CI: 0.53, 0.79, P < 0.001) women; obese black (r 0.59, 95 % CI: 0.46, 0.70, P < 0.001) and white (r 0.56, 95 % CI: 0.30, 0.74, P < 0.001) women. NIR under-predicted BF% compared to DXA in black women (normal-weight, - 4.36 (sd 4.13) % and obese, - 3.41 (sd 3.72) %), while smaller mean differences were observed in white women (normal-weight, - 0.29 (sd 4.19) % and obese, - 0.81 (sd 3.09) %), irrespective of normal-weight or obese status (P < 0.001). In obese subjects, NIR-derived BF % did not measure values greater than approximately 45 %, while the maximum DXA-derived measure was 58 %. In conclusion, although there was a significant relationship between NIR- and DXA-derived BF %, NIR under-predicted BF % in normal-weight and obese black South African women compared to DXA, but to a greater extent in subjects with very high levels of adiposity (>45 %). The results of single-site NIR as a measure of BF % should therefore be interpreted with caution, particularly in women of African descent and in those with very high levels of adiposity.

Emergence of a new national health services research alliance.

Although underrepresented to date, PPOs have the potential to become major contributors to health services research. However, policy and health plan decision makers must be informed about the unique features and contributions of PPOs. The authors describe a unique health services research coalition established among 13 Blue Cross and Blue Shield plans nationwide and the Kerr L. White Institute for Health Services Research (Decatur, GA), in collaboration with research institutions and government agencies, that features multiple health plan products within commercial, Medicare, and Medicaid enrollments, but with a specific emphasis on PPOs.

Recent tax changes may assist treatment of obesity.

The U.S. Surgeon General's Call to Action on Overweight and Obesity 2001 proposes inclusion of health care providers in prevention efforts and suggests classification of obesity as a disease category for reimbursement coding. Physician counseling on and referral for physical activity is generally recognized as a component of obesity treatment, but data on the effectiveness of these measures remain inconclusive. Recent changes in the federal tax law may influence physicians' and health plans' roles in promoting physical activity.

Promoting physical activity: a profile of health plan programs and initiatives.

A study was conducted to capture information on health plans' initiatives to promote physical activity among members and in community settings. This investigation was based on a descriptive nationwide study of American Association of Health Plans- and Blue Cross and Blue Shield Association-member plans conducted from October 2001 to February 2002. Sixty individuals with responsibility for health-promotion programs were surveyed, and 24 provided in-depth interviews. The measures used in this evaluation were the number and type of member- and community-based physical activity programs/initiatives offered by health plans, and the types of programs evaluated. Information was captured on more than 373 physical activity initiatives. Thirty-five percent of surveyed health plans responded, representing more than 62 million health plan members; the participation rate for in-depth interviews was 80%. Most health plans integrate physical activity messages into routine services for members (92%) and sponsor community races/walks and health fairs (85%). Physical activity programs are offered to improve member health (92%), increase member satisfaction (80%), and reduce long-term health care costs (62%). Few rigorous evaluations have been conducted on these programs, and return-on-investment data are scarce. Although some health plans currently play a relatively active role in promoting physical fitness to their members and the community, multiple opportunities exist for health plan involvement in various settings with different populations.

Diagnostic ability of obesity measures to identify metabolic risk factors in South African women.

BACKGROUND: Currently, guidelines for obesity thresholds relating to metabolic risk in South African women have not been established. Therefore, the aim of the study was to investigate the level and diagnostic ability of obesity measures [waist circumference (WC), waist-to-height ratio (WHtR), and visceral adipose tissue (VAT) area] to identify black and white South African women with elevated blood pressure, dyslipidemia, and insulin resistance. METHODS: Blood pressure, fasting insulin, glucose, and lipids were measured in 241 black and 188 white South African women. Receiver operator characteristic (ROC) curve analyses were performed to determine the diagnostic ability of WC, WHtR, and computer tomography (CT)-derived VAT to identify subjects above metabolic risk thresholds. The Youden index was used to calculate obesity thresholds for metabolic risk variables. RESULTS: WC, WHtR, and VAT were significant determinants of all metabolic risk variables (P<0.05), and differences in the ROC area under the curve (AUC) between obesity measures were small (≈0.08) for all metabolic risk variables, in both ethnic groups. However, the ROC AUC vales for all obesity measures were greater in white compared to black women (P<0.01). WC and VAT thresholds were lower in black women compared to white women, whereas WHtR thresholds varied less between ethnicities. CONCLUSIONS: Due to the cost, access, and radiation exposure, CT-derived VAT is not recommended above the use of simple anthropometric measures (WC and WHtR) for the determination of metabolic risk. Furthermore, thresholds of WHtR, due to low variability between ethnicities, may be more useful than WC for ethnic comparisons of risk.

Dual-energy X-ray absorptiometry and anthropometric estimates of visceral fat in Black and White South African Women.

Visceral adipose tissue (VAT) is associated with increased risk for cardiovascular disease, and therefore, accurate methods to estimate VAT have been investigated. Computerized tomography (CT) is the gold standard measure of VAT, but its use is limited. We therefore compared waist measures and two dual-energy X-ray absorptiometry (DXA) methods (Ley and Lunar) that quantify abdominal regions of interest (ROIs) to CT-derived VAT in 166 black and 143 white South African women. Anthropometry, DXA ROI, and VAT (CT at L4-L5) were measured. Black women were younger (P < 0.001), shorter (P < 0.001), and had higher body fat (P < 0.05) than white women. There were no ethnic differences in waist (89.7 +/- 18.2 cm vs. 90.1 +/- 15.6 cm), waist:height ratio (WHtR, 0.56 +/- 0.12 vs. 0.54 +/- 0.09), or DXA ROI (Ley: 2.2 +/- 1.5 vs. 2.1 +/- 1.4; Lunar: 2.3 +/- 1.4 vs. 2.3 +/- 1.5), but black women had less VAT, after adjusting for age, height, weight, and fat mass (76 +/- 34 cm(2) vs. 98 +/- 35 cm(2); P < 0.001). Ley ROI and Lunar ROI were correlated in black (r = 0.983) and white (r = 0.988) women. VAT correlated with DXA ROI (Ley: r = 0.729 and r = 0.838, P < 0.01; Lunar: r = 0.739 and r = 0.847, P < 0.01) in black and white women, but with increasing ROI android fatness, black women had less VAT. Similarly, VAT was associated with waist (r = 0.732 and r = 0.836, P < 0.01) and WHtR (r = 0.721 and r = 0.824, P < 0.01) in black and white women. In conclusion, although DXA-derived ROIs correlate well with VAT as measured by CT, they are no better than waist or WHtR. Neither DXA nor anthropometric measures are able to accurately distinguish between high and low levels of VAT between population groups.

The atypical presentation of the metabolic syndrome components in black African women: the relationship with insulin resistance and the influence of regional adipose tissue distribution.

The appropriateness of the metabolic syndrome criteria as an indicator of cardiovascular disease risk has been challenged in black Africans. Hence, the aims of this study were (1) to examine the level of agreement between the International Diabetes Federation (IDF) and the National Cholesterol Education Program Adult Treatment Panel III (ATP III) metabolic syndrome criteria, which differ in their emphasis on central obesity; (2) to investigate the degree to which these criteria predict insulin resistance, as estimated by the homeostasis model assessment of insulin resistance (HOMA-IR); and (3) to investigate the extent to which a diagnosis of the metabolic syndrome and insulin resistance may be explained by body fat and its distribution. In 103 normal-weight (body mass index or=30 kg/m(2), mean: 33.9 +/- 5.5 kg/m(2)) urbanized black South African women (27 +/- 7 years old), body composition (dual-energy x-ray absorptiometry), fat distribution (waist and computed tomography), blood pressure, fasting glucose, HOMA-IR, and lipid profiles were measured. Insulin resistance was defined as the upper tertile of HOMA-IR. The overall proportion of individuals who met the IDF and ATP III metabolic syndrome criteria were 13% and 10%, respectively. Agreement was high between the IDF and ATP III metabolic syndrome criteria (kappa = 0.87); however, neither criteria predicted HOMA-IR (kappa = 0.16, 95% confidence interval: 0.05-0.27 and 0.14, 95% confidence interval: 0.05-0.27, respectively). Visceral adipose tissue was the largest contributor to diagnosis of the metabolic syndrome, and waist alone (>80 cm or >88 cm) had an improved specificity (21% or 18% higher, respectively) and positive predictive value (64% or 57% higher, respectively) for identifying insulin resistance compared with the metabolic syndrome criteria. Waist circumference was a better predictor of HOMA-IR than the IDF or ATP III metabolic syndrome criteria in young black African women without known disease. The measurement of waist circumference, as an indicator of disease risk, should therefore be encouraged in the public health setting.

Association between the 4 bp proinsulin gene insertion polymorphism (IVS-69) and body composition in black South African women.

The objective of the study was to examine the association between a functional 4 bp proinsulin gene insertion polymorphism (IVS-69), fasting insulin concentrations, and body composition in black South African women. Body composition, body fat distribution, fasting glucose and insulin concentrations, and IVS-69 genotype were measured in 115 normal-weight (BMI<25 kg/m2) and 138 obese (BMI>or=30 kg/m2) premenopausal women. The frequency of the insertion allele was significantly higher in the class 2 obese (BMI>or=35 kg/m2) compared with the normal-weight group (P=0.029). Obese subjects with the insertion allele had greater fat mass (42.3+/-0.9 vs. 38.9+/-0.9 kg, P=0.034) and fat-free soft tissue mass (47.4+/-0.6 vs. 45.1+/-0.6 kg, P=0.014), and more abdominal subcutaneous adipose tissue (SAT, 595+/-17 vs. 531+/-17 cm2, P=0.025) but not visceral fat (P=0.739), than obese homozygotes for the wild-type allele. Only SAT was greater in normal-weight subjects with the insertion allele (P=0.048). There were no differences in fasting insulin or glucose levels between subjects with the insertion allele or homozygotes for the wild-type allele in the normal-weight or obese groups. In conclusion, the 4 bp proinsulin gene insertion allele is associated with extreme obesity, reflected by greater fat-free soft tissue mass and fat mass, particularly SAT, in obese black South African women.