Platelets: a critical link between inflammation and microvascular dysfunction

The longevity-associated BPIFB4 gene guarantees vascular homeostasis and immune protection through platelets

Beyond their activity in hemostasis and thrombosis, recent advances attribute platelets a pro-youthful role capable to attenuate immune senescence and age-related neuroinflammation. Previous studies from our group associated a polymorphic haplotype variant in the BPIFB4 gene (LAV-BPIFB4) with exceptional longevity. Transfer of the LAV-BPIFB4 in preclinical models has proved strategic to cope with frailty conditions, aging-related events, e.g., cardiovascular ones, and immune dysfunction mainly through a favorable conditioning of the immune system. However, whether platelets participate in LAV-BPIFB4 therapeutic action is currently unknown. Herein, we discovered that platelets were instrumental in boosting the favorable health outcomes of the systemic AAV-LAV-BPIFB4 gene transfer in vivo, as the α-CD42b platelet depletion completely abolished the vascular protective action of LAV-BPIFB4 and suppressed its pro-resolutive CD206 + anti-/CD86 + pro-inflammatory Ly6C + monocyte skewing to LPS stimulation. Of note, this is associated with a huge drop in the protective levels of BPIFB4 in the plasma of AAV-LAV-BPIFB4-injected C57BL/6 mice, indicating that plasma circulating platelets may be a reservoir of the BPIFB4 protein. Indeed, we noticed that BPIFB4 was released by human platelets, a process that is amplified in LAV-allele carrier donors. Accordingly, lentivirus-mediated overexpression of human LAV-BPIFB4 isoform, but not WT-BPIFB4 isoform was able in leading differentiated megakaryocytes to release more platelet-like-particles enriched for BPIFB4. In addition, in vitro, the M2 macrophage polarization increased when releasate from platelets, and even more from LAV pre-stimulated once, was added in monocyte cell culture. Our data suggest that platelet release of BPIFB4 and of yet-to-be-determined unidentified factors mediates the therapeutic efficacy of LAV-BPIFB4 treatment.

Mood disorders and 5-HTR2A genetic variants - the moderator effect of inflammation on expression of affective polarity phenotype

BACKGROUND

Although repeatedly confirmed, the molecular nature of gene-environment (GxE) interactions has rarely been investigated in the clinical context of mood disorders. This study assesses the relationship between HTR2A genetic variants and the modulatory effect of inflammation in a collective cohort of patients with major depressive disorder (MDD) and bipolar disorder (BD), as a unified group with two distinct phenotypes.

METHODS

The study included 138 patients with acute mood episodes (BD = 83; MDD = 55). HTR2A rs6313 and rs6314 genotyping was performed while measuring platelet-derived indicators of inflammation (platelet count (PLT), mean platelet volume (MPV), plateletcrit, and platelet distribution width) and the MPV/PLT ratio.

RESULTS

The HTR2A rs6313 variant is a significant predictor of the polarity phenotype in mood disorders, with the MPV/PLT ratio moderating this relationship, but only under low-inflammatory conditions. In more pronounced inflammatory states, genetic influences lose their predictive role.

CONCLUSIONS

To our knowledge, this is the first study to investigate the complex interplay between platelet-derived indicators of inflammation and HTR2A variants in the context of mood disorders. Without pro-inflammatory conditions, mood disorders seem to be more genetically determined. Under pro-inflammatory conditions, phenotypic presentation is less dependent on genetic factors. GxE interactions in mood disorders are multifaceted, context-dependent and relevant for assessing their clinical presentation and course.

Donor plasma VEGF-A as a biomarker for myocardial injury and primary graft dysfunction after heart transplantation

BACKGROUND

Vascular endothelial growth factor (VEGF)-A is an angiogenic and proinflammatory cytokine with profound effects on microvascular permeability and vasodilation. Several processes may induce VEGF-A expression in brain-dead organ donors. However, it remains unclear whether donor VEGF-A is linked to adverse outcomes after heart transplantation.

METHODS

We examined plasma VEGF-A levels from 83 heart transplant donors as well as the clinical data of these donors and their respective recipients operated between 2010 and 2016. The donor plasma was analyzed using Luminex-based Multiplex and confirmed with a single-target ELISA. Based on donor VEGF-A plasma levels, the recipients were divided into 3 equal-sized groups (low VEGF <500 ng/liter, n = 28; moderate VEGF 500-3000 ng/liter, n = 28; and high VEGF >3000 ng/liter, n = 27). Biochemical and clinical parameters of myocardial injury as well as heart transplant and kidney function were followed-up for one year, while rejection episodes, development of cardiac allograft vasculopathy, and mortality were monitored for 5 years.

RESULTS

Baseline parameters were comparable between the donor groups, except for age, where median ages of 40, 45, and 50 were observed for low, moderate, and high donor plasma VEGF levels groups, respectively, and therefore donor age was included as a confounding factor. High donor plasma VEGF-A levels were associated with pronounced myocardial injury (TnT and TnI), a higher inotrope score, and a higher incidence of primary graft dysfunction in the recipient after heart transplantation. Furthermore, recipients with allografts from donors with high plasma VEGF-A levels had a longer length of stay in the intensive care unit and the hospital, and an increased likelihood for prolonged renal replacement therapy.

CONCLUSIONS

Our findings suggest that elevated donor plasma VEGF-A levels were associated with adverse outcomes in heart transplant recipients, particularly in terms of myocardial injury, primary graft dysfunction, and long-term renal complications. Donor VEGF-A may serve as a potential biomarker for predicting these adverse outcomes and identifying extended donor criteria.

Unleashing the biomimetic targeting potential of platelet-derived nanocarriers on atherosclerosis

Atherosclerosis, the primary mechanism underlying the development of many cardiovascular illnesses, continues to be one of the leading causes of mortality worldwide. Platelet (PLT), which are essential for maintaining body homeostasis, have been strongly linked to the onset of atherosclerosis at various stages due to their inherent tendency to bind to atherosclerotic lesions and show an affinity for plaques. Therefore, mimicking PLT's innate adhesive features may be necessary to effectively target plaques. PLT-derived nanocarriers have emerged as a promising biomimetic targeting strategy for treating atherosclerosis due to their numerous advantages. These advantages include excellent biocompatibility, minimal macrophage phagocytosis, prolonged circulation time, targeting capability for impaired vascular sites, and suitability as carriers for anti-atherosclerotic drugs. Herein, we discuss the role of PLT in atherogenesis and propose the design of nanocarriers based on PLT-membrane coating and PLT-derived vesicles. These nanocarriers can target multiple biological elements relevant to plaque development. The review also emphasizes the current challenges and future research directions for the effective utilization of PLT-derived nanocarriers in treating atherosclerosis.

Inflammation, Sepsis, and the Coagulation System

Sepsis has been a major health problem for centuries and it is still the leading cause of hospital deaths. Several studies in the past decades have identified numerous biochemical abnormalities in severe cases, and many of these studies provide evidence of the perturbation of the hemostatic system. This can result in complications, such as disseminated intravascular coagulation that can lead to multiorgan failure. Nevertheless, large clinical studies have demonstrated that the simple approach of inhibiting the coagulation processes by any means fails to provide significant improvement in the survival of septic patients. A cause of this failure could be the fact that in sepsis the major clinical problems result not primarily from the presence of the infective agent or enhanced coagulation but from the complex dysregulated systemic host response to pathogens. If this overt reaction is not fully deciphered, appropriate interference is highly unlikely and any improvement by conventional therapeutic interventions would be limited. Cellular activation in sepsis can be targeted by novel approaches like inhibition of the heterotypic cellular interactions of blood cells by targeting surface receptors or posttranscriptional control of the hemostatic system by noncoding ribonucleic acid (RNA) molecules. Stable RNA molecules can affect the expression of several proteins. Thus, it can be anticipated that modulation of microRNA production would result in a multitude of effects that may be beneficial in septic cases. Here, we highlight some of the recent diagnostic possibilities and potential novel routes of the dysregulated host response.

Soluble platelet selectin and platelets in COVID-19: a multifaceted connection

The COVID-19 pandemic has brought to light the intricate relationship between platelets, soluble platelet selectin (sP-selectin), and disease pathogenesis. Platelets, traditionally recognized for their role in hemostasis, have emerged as key contributors to the immunothrombotic complications observed in COVID-19 patients. Concurrently, elevated levels of sP-selectin, indicative of platelet activation and endothelial injury, have been consistently identified in COVID-19 patients and have shown associations with disease severity and adverse outcomes. This multifaceted connection underscores the pivotal role of platelets and sP-selectin in orchestrating thromboinflammation, vascular dysfunction, and disease progression in COVID-19. Platelet activation triggers the release of inflammatory mediators and promotes platelet-leukocyte interactions, amplifying the systemic inflammatory response and exacerbating endothelial injury. Additionally, platelet-derived factors contribute to microvascular thrombosis, further exacerbating tissue damage and organ dysfunction in severe COVID-19. Elevated sP-selectin levels serve as biomarkers for disease severity and prognostication, aiding in risk stratification and early identification of patients at higher risk of adverse outcomes. Therapeutic strategies targeting platelet dysfunction and sP-selectin-mediated pathways hold promise in mitigating thromboinflammation and improving outcomes in COVID-19 patients. Antiplatelet agents, platelet inhibitors, and anti-inflammatory therapies represent potential interventions to attenuate platelet activation, inhibit platelet-leukocyte interactions, and alleviate endothelial dysfunction. A comprehensive understanding of the multifaceted connection between platelets, sP-selectin, and COVID-19 pathogenesis offers opportunities for tailored therapeutic approaches aimed at mitigating thromboinflammation and improving patient outcomes in this complex and challenging clinical setting.

Relationship Between Platelet Parameters and Eosinophils with Disease Severity, CRP and Treatment in Stable COPD

Objectives

Chronic obstructive pulmonary disease (COPD) is a complex inflammatory condition that primarily impairs respiration but can also affect hemostasis. This study aimed to determine differences in platelet-related parameters and eosinophil between COPD patients and healthy controls.

Methods

We included 149 patients with stable COPD and 30 healthy controls who were recruited from the outpatient department of Chest Diseases. Complete blood count, including platelet count (Plt), and C-reactive protein were measured. Other platelet-related parameters were determined, including mean platelet volume (MPV), platelet distribution width (PDW), plateletcrit (Pct), their ratios (MPV/Plt, MPV/Pct, PDW/Plt, PDW/Pct), and platelet to lymphocyte ratio (PLR).

Results

COPD patients and controls did not show significant differences in platelet parameters (Plt, Pct, PDW, MPV, PDW/Pct, MPV/Pct). PLR was significantly higher in the patient groups than in the control group (p=0.009). Correlation between platelet count and PLR (p=0.047; p=0.05) showed borderline significance. However, we found no correlation between the patients' CRP levels, Pct, PDW, PDW/Pct, MPV/Pct and MPV values. There were no significant differences in platelet parameters in patients using and not using long-acting muscarinic antagonists (LAMA). We did not find differences in eosinophil levels among COPD severity grades.

Conclusion

In our study, we found that PLR is elevated in COPD. PLR could be a useful and easily accessible parameter to evaluate ongoing inflammation in stable COPD. Large-scale studies are warranted to further investigate the role of platelet and eosinophil parameters in COPD.

A circle of life: platelet and megakaryocyte cytoskeleton dynamics in health and disease

Platelets are blood cells derived from megakaryocytes that play a central role in regulating haemostasis and vascular integrity. The microtubule cytoskeleton of megakaryocytes undergoes a critical dynamic reorganization during cycles of endomitosis and platelet biogenesis. Quiescent platelets have a discoid shape maintained by a marginal band composed of microtubule bundles, which undergoes remarkable remodelling during platelet activation, driving shape change and platelet function. Disrupting or enhancing this process can cause platelet dysfunction such as bleeding disorders or thrombosis. However, little is known about the molecular mechanisms underlying the reorganization of the cytoskeleton in the platelet lineage. Recent studies indicate that the emergence of a unique platelet tubulin code and specific pathogenic tubulin mutations cause platelet defects and bleeding disorders. Frequently, these mutations exhibit dominant negative effects, offering valuable insights into both platelet disease mechanisms and the functioning of tubulins. This review will highlight our current understanding of the role of the microtubule cytoskeleton in the life and death of platelets, along with its relevance to platelet disorders.

Clinical Outcomes and Systemic Complications Related to the Severity and Etiology of Status Epilepticus Using a Common Data Model

BACKGROUND

Status epilepticus (SE) is a critical neurological emergency in patients with neurological and nonneurological diseases. Mortality rises with SE severity. However, whether brain injury or systemic organ dysfunction causes death after SE remains unclear. We studied clinical outcomes and systemic dysfunctions associated with SE using standardized data from the common data model. This model includes clinical evaluations and treatments that provide real-world evidence for standard practice.

METHODS

This retrospective cohort study used the common data model database of a single tertiary academic medical center. Patients diagnosed with SE (corresponding to G41 of the International Classification of Diseases 10 and administration of antiseizure medication) between January 1, 2001, and January 1, 2018, were enrolled. Demographics, classifications of SE severity, and outcomes were collected as operational definitions by using a common data model format. Systemic complications were defined based on the Sequential Organ Failure Assessment criteria.

RESULTS

The electronic medical records of 1,825,196 patients were transformed into a common data model, and 410 patients were enrolled. The proportion of patients classified as having nonrefractory SE was 65.4% (268/410), followed by refractory (28.5%, 117/410) and super-refractory SE (6.1%, 25/410). Patients with more severe SE had longer intensive care unit and hospital stays. Renal dysfunction and thrombocytopenia were higher in the in-hospital death group (P = 0.002 and 0.003, respectively). In multivariable analysis, the Acute Physiology and Chronic Health Evaluation II score and platelet count were significantly different in the in-hospital death group (odds ratio, 1.169, P = 0.004; and 0.989, P = 0.043).

CONCLUSIONS

Systemic complications after SE, especially low platelet counts, were linked to worse outcomes and increased mortality in a common data model. The common data model offers expandability and comprehensive analysis, making it a potentially valuable tool for SE research.

Association of Leukocyte, Erythrocyte, and Platelet Counts with Metabolic Syndrome and Its Components in Young Individuals without Overt Signs of Inflammation: A Cross-Sectional Study

The presence of metabolic syndrome (MetS) increases the risk of developing type 2 diabetes, cardiovascular diseases, and mortality. MetS is associated with increased leukocyte or erythrocyte counts. In 16- to 20-year-old males (n = 1188) and females (n = 1231) without signs of overt inflammation, we studied whether the presence of MetS and its components results in elevated blood cell counts. The leukocyte, erythrocyte, and thrombocyte counts significantly but weakly correlated with the continuous MetS score, MetS components, uric acid, and C-reactive protein levels both in males (r = -0.09 to 0.2; p < 0.01) and females (r = -0.08 to 0.2; p < 0.05). Subjects with MetS had higher leukocyte (males: 6.2 ± 1.3 vs. 6.9 ± 1.2 × 109/L; females 6.6 ± 1.5 vs. 7.5 ± 1.6 × 109/L; p < 0.001), erythrocyte (males: 5.1 ± 0.3 vs. 5.3 ± 0.3 × 1012/L; females: 4.5 ± 0.3 vs. 4.8 ± 0.3 × 1012/L; p < 0.001), and platelet counts (males: 245 ± 48 vs. 261 ± 47 × 109/L; females: 274 ± 56 vs. 288 ± 74 × 109/L; p < 0.05) than those without MetS. With the exception of platelet counts in females, the blood counts increased with the number of manifested MetS components. Phenotypes with the highest average leukocyte, erythrocyte, or platelet counts differed between sexes, and their prevalence was low (males: 0.3% to 3.9%; females: 1.2% to 2.7%). Whether functional changes in blood elements accompany MetS and whether the increase in blood counts within the reference ranges represents a risk for future manifestation of cardiometabolic diseases remain unanswered.

Trends among platelet function, arterial calcium, and vascular function measures

Arterial tonometry and vascular calcification measures are useful in cardiovascular disease (CVD) risk assessment. Prior studies found associations between tonometry measures, arterial calcium, and CVD risk. Activated platelets release angiopoietin-1 and other factors, which may connect vascular structure and platelet function. We analyzed arterial tonometry, platelet function, aortic, thoracic and coronary calcium, and thoracic and abdominal aorta diameters measured in the Framingham Heart Study Gen3/NOS/OMNI-2 cohorts (n = 3,429, 53.7% women, mean age 54.4 years ±9.3). Platelet reactivity in whole blood or platelet-rich plasma was assessed using 5 assays and 7 agonists. We analyzed linear mixed effects models with platelet reactivity phenotypes as outcomes, adjusting for CVD risk factors and family structure. Higher arterial calcium trended with higher platelet reactivity, whereas larger aortic diameters trended with lower platelet reactivity. Characteristic impedance (Zc) and central pulse pressure positively trended with various platelet traits, while pulse wave velocity and Zc negatively trended with collagen, ADP, and epinephrine traits. All results did not pass a stringent multiple test correction threshold (p < 2.22e-04). The diameter trends were consistent with lower shear environments invoking less platelet reactivity. The vessel calcium trends were consistent with subclinical atherosclerosis and platelet activation being inter-related.

TIME-DEPENDENT CHANGES IN PROINFLAMMATORY MEDIATORS ARE ASSOCIATED WITH TRAUMA-RELATED VENOUS THROMBOEMBOLISM

ABSTRACT

Background: Tissue trauma and hemorrhage result in pronounced activation of the innate immune system. Given known crosstalk between inflammation and coagulation, soluble inflammatory mediators could be associated with venous thromboembolisms (VTEs) after major trauma. Objectives : This study aimed to identify plasma inflammatory mediators that are independent predictors of VTE risk in trauma patients. Methods: We performed a secondary analysis of the Pragmatic Randomized Optimal Platelets and Plasma Ratios (PROPPR) study. Plasma levels of 27 cytokines/chemokines were measured by Bio-Plex at admission and 2, 4, 6, 12, 24, 48, and 72 h later. Patients who died from exsanguination or within 24 h were excluded. Mann-Whitney tests were performed to assess no-VTE and VTE groups at each time point. Multivariable logistic regression was used to determine the adjusted effects of inflammatory mediators on VTE risk. Results: Eighty-six of the 575 patients (15%) included developed VTE. Interleukin (IL)-1ra, IL-6, IL-8, IL-10, eotaxin, granulocyte colony-stimulating factor, interferon-γ-inducible protein, monocyte chemoattractant protein 1 (MCP-1), and chemokine ligand 5 (regulated on activation, normal T cell expressed and secreted) were all significantly increased among VTE patients. Multivariable analyses demonstrated that IL-6, IL-8, interferon-γ-inducible protein, and MCP-1 were independently associated with VTE. Cox proportional hazards modeling identified IL-6, IL-8, and MCP-1 as independent predictors of accelerated VTE development. We identified significant correlations between inflammation and markers of coagulation and endothelial activation. Conclusion: Sustained systemic inflammation is a key driver of VTE risk after major trauma. Therapeutics targeting innate immune activation should be considered for development of future multimodal strategies to augment current VTE prophylaxis.

Systemic immune-inflammation index in patients with generalized stage III grade C periodontitis

OBJECTIVES

Systemic immune-inflammation index (SII) is a novel, inflammatory biomarker whose role in predicting several chronic systemic diseases has been recently identified. However, its association with generalized stage III grade C periodontitis in young adults remains unknown.

MATERIAL AND METHODS

The study is a multicentered, double-blind, hospital-based case-control clinical study. Periodontal examination comprised of recording plaque index, sites with bleeding on probing, pocket depth and clinical attachment loss for patients with generalized stage III grade C periodontitis and periodontally healthy group. Complete blood counts were obtained and used for calculating SII, neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio. Collected data were then subjected to statistical analyses.

RESULTS

SII was significantly higher in patients with generalized stage III grade C periodontitis compared to periodontally healthy individuals (723.87 vs. 537.74 × 109 /L, p < 0.0001). SII is associated with severe periodontitis in young adults (odds ratio [OR]:11.86, 95% CI 9.61-20.76, p < 0.0001) after adjusting for factors found significant in univariate analysis. Receiver operative curve analysis demonstrated a fair predictive validity of SII in detecting generalized stage III grade C periodontitis in young adults (AUC: 0.766, 95%CI 0.731-0.799, p < 0.0001, sensitivity 81.27%, specificity 76.50% and diagnostic accuracy 78.89%). SII did not exhibit superior predictive validity when compared with NLR in the context of generalized stage III grade C periodontitis (AUC for SII: 0.766, 95%CI 0.731-0.799, AUC for NLR: 0.788, 95% CI 0.754-0.819; p = 0.28).

CONCLUSION

SII is associated with generalized stage III grade C periodontitis in young adults.

Cardiovascular Diseases and Marine Oils: A Focus on Omega-3 Polyunsaturated Fatty Acids and Polar Lipids

Cardiovascular diseases (CVD) remain the leading cause of death across the globe, hence, establishing strategies to counteract CVD are imperative to reduce mortality and the burden on health systems. Dietary modification is an effective primary prevention strategy against CVD. Research regarding dietary supplementation has become increasingly popular. This review focuses on the current in vivo, in vitro, and epidemiological studies associated with that of omega-3 polyunsaturated fatty acids (n-3 PUFAs) and polar lipids (PLs) and how they play a role against CVD. Furthermore, this review focuses on the results of several major clinical trials examining n-3 PUFAs regarding both primary and secondary prevention of CVD. Notably, we place a lens on the REDUCE-IT and STRENGTH trials. Finally, supplementation of PLs has recently been suggested as a potential alternative avenue for the reduction of CVD incidence versus neutral forms of n-3 PUFAs. However, the clinical evidence for this argument is currently rather limited. Therefore, we draw on the current literature to suggest future clinical trials for PL supplementation. We conclude that despite conflicting evidence, future human trials must be completed to confirm whether PL supplementation may be more effective than n-3 PUFA supplementation to reduce cardiovascular risk.

The effects of type of recovery in resistance exercise on responses of platelet indices and hemodynamic variables

To examine the effects of two different volume-matched resistance exercise (RE) recovery protocols (passive and active) on platelet indices and hemodynamic variables. Twelve Healthy participants (mean ± SD; 25 ± 3 yrs) completed a traditional resistance exercise (TRE) protocol that included three sets of six repetitions at 80% one repetition maximum (1RM) with two minutes passive recovery between sets, exercises and an interval resistance exercise (IRE) protocol that included three sets of six repetitions at 60%1RM followed by active recovery including six repetitions of the same exercise at 20%1RM. Blood samples for multiple platelet indices were taken before the protocols, immediately-post (IP), and after 1-hour recovery. Hemodynamic variables were measured before, IP, and every five minutes during recovery. Mean platelet volume and platelet large cell ratio P_LCR decreased from baseline to recovery. Heart rate (HR) and rate pressure product (RPP) were augmented at IP following IRE compared to TRE. HR was significantly elevated for 20 minutes after both RE protocols, and RPP recovered by five minutes. Systolic blood pressure was increased at IP compared to baseline and all recovery time points for both RE protocols. Our research demonstrated that both RE protocols, produced transient increases in platelet indices (MPV, and P_LCR) and hemodynamic variables (SBP, HR, and RPP), all of which returned to baseline within an hour. Notably, the IRE protocol elicited a greater increase in HR and RPP compared to the TRE protocol.

The Role of Antiplatelet in the Management of Sickle Cell Disease Patients

Sickle cell disease (SCD) is a genetic disorder characterized by abnormal hemoglobin, leading to red blood cell deformities and subsequent vaso-occlusive events. Platelet activation and adhesion play a significant role in the pathophysiology of SCD, contributing to the development of complications such as vaso-occlusive events, stroke, acute chest syndrome, and other manifestations. Antiplatelet therapy has emerged as a potential strategy to mitigate these complications by modulating the platelet function and reducing thrombotic events. This review article provides an overview of antiplatelet therapy's role in managing SCD patients. It discusses the pathophysiological abnormalities in the platelet function in SCD, the rationale for antiplatelet therapy, and the evidence supporting its use in various clinical scenarios. The article explores aspirin as the primary antiplatelet agent in SCD, including its mechanism of action, dosing considerations, and efficacy and safety data. Additionally, it highlights other antiplatelet agents, such as clopidogrel, prasugrel, ticagrelor, and emerging therapies under investigation. Clinical applications of antiplatelet therapy in primary and secondary prevention and the management of acute chest syndrome and other SCD complications are also discussed. Safety considerations are emphasized, including bleeding risk assessment, monitoring, and patient selection for antiplatelet therapy. Finally, the review highlights future research and clinical practice directions, including the development of novel antiplatelet agents, combination therapies, and the integration of antiplatelet therapy with other SCD treatments. Overall, this review provides a comprehensive understanding of the current role of antiplatelet therapy in SCD management, the challenges faced, and future directions for improving patient outcomes.

Post-Ischemic Permeability of the Blood-Brain Barrier to Amyloid and Platelets as a Factor in the Maturation of Alzheimer's Disease-Type Brain Neurodegeneration

The aim of this review is to present evidence of the impact of ischemic changes in the blood-brain barrier on the maturation of post-ischemic brain neurodegeneration with features of Alzheimer's disease. Understanding the processes involved in the permeability of the post-ischemic blood-brain barrier during recirculation will provide clinically relevant knowledge regarding the neuropathological changes that ultimately lead to dementia of the Alzheimer's disease type. In this review, we try to distinguish between primary and secondary neuropathological processes during and after ischemia. Therefore, we can observe two hit stages that contribute to Alzheimer's disease development. The onset of ischemic brain pathology includes primary ischemic neuronal damage and death followed by the ischemic injury of the blood-brain barrier with serum leakage of amyloid into the brain tissue, leading to increased ischemic neuronal susceptibility to amyloid neurotoxicity, culminating in the formation of amyloid plaques and ending in full-blown dementia of the Alzheimer's disease type.

Platelet-monocyte aggregates: molecular mediators of thromboinflammation

Platelets, key facilitators of primary hemostasis and thrombosis, have emerged as crucial cellular mediators of innate immunity and inflammation. Exemplified by their ability to alter the phenotype and function of monocytes, activated platelets bind to circulating monocytes to form monocyte-platelet aggregates (MPA). The platelet-monocyte axis has emerged as a key mechanism connecting thrombosis and inflammation. MPA are elevated across the spectrum of inflammatory and autoimmune disorders, including cardiovascular disease, systemic lupus erythematosus (SLE), and COVID-19, and are positively associated with disease severity. These clinical disorders are all characterized by an increased risk of thromboembolic complications. Intriguingly, monocytes in contact with platelets become proinflammatory and procoagulant, highlighting that this interaction is a central element of thromboinflammation.

Comparison between neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio as predictors of mortality on Fournier's gangrene cases

Introduction

Fournier's gangrene (FG) is an infection of the subcutaneous tissue and fascia that progresses quickly and leads to necrosis. It is more prevalent in male patients and immunocompromised individuals, such as those suffering from uncontrolled diabetes. It has a high mortality rate, which makes its early identification and clinical suspicion critical. This study aimed to compare two laboratory parameters, neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR), and to predict the mortality of FG in a tertiary care hospital.

Methods

In a retrospective study, data was retrieved from medical records for the period from January 2014 to December 2020, of patients diagnosed with FG. Recorded data that is age, sex, comorbidities, mortality, and laboratory results (PLR and NLR) were used to assess determinants of survival.

Results

There were 23 (17.04%) nonsurvivors among the 135 subjects studied. The mean age was 50.9 ± 14.9 years and men were 103 (83%) patients. Among the participants, diabetes mellitus was the most frequent comorbidity at 74 (54.81%) patients. NLR ≥8 was statistically significant (P = 0.013) for identifying mortality, while PLR >140 was not. In multivariate analysis, NLR ≥8 was found to be a reliable predictor of the FG mortality rate (adjusted odds ratio 12.062, confidence interval 95% 2.115-68.778, P = 0.005).

Conclusion

NLR had prognosis predictive value for FG, whereas PLR did not.

Megakaryocytes respond during sepsis and display innate immune cell behaviors

Megakaryocytes (MKs) are precursors to platelets, the second most abundant cells in the peripheral circulation. However, while platelets are known to participate in immune responses and play significant functions during infections, the role of MKs within the immune system remains largely unexplored. Histological studies of sepsis patients identified increased nucleated CD61+ cells (MKs) in the lungs, and CD61+ staining (likely platelets within microthrombi) in the kidneys, which correlated with the development of organ dysfunction. Detailed imaging cytometry of peripheral blood from patients with sepsis found significantly higher MK counts, which we predict would likely be misclassified by automated hematology analyzers as leukocytes. Utilizing in vitro techniques, we show that both stem cell derived MKs (SC MKs) and cells from the human megakaryoblastic leukemia cell line, Meg-01, undergo chemotaxis, interact with bacteria, and are capable of releasing chromatin webs in response to various pathogenic stimuli. Together, our observations suggest that MK cells display some basic innate immune cell behaviors and may actively respond and play functional roles in the pathophysiology of sepsis.

Prediction of Poor Outcome after Successful Thrombectomy in Patients with Severe Acute Ischemic Stroke: A Pilot Retrospective Study

Several baseline hematologic and metabolic laboratory parameters have been linked to acute ischemic stroke (AIS) clinical outcomes in patients who successfully recanalized. However, no study has directly investigated these relationships within the severe stroke subgroup. The goal of this study is to identify potential predictive clinical, lab, and radiographic biomarkers in patients who present with severe AIS due to large vessel occlusion and have been successfully treated with mechanical thrombectomy. This single-center, retrospective study included patients who experienced AIS secondary to large vessel occlusion with an initial NIHSS score ≥ 21 and were recanalized successfully with mechanical thrombectomy. Retrospectively, demographic, clinical, and radiologic data from electronic medical records were extracted, and laboratory baseline parameters were obtained from emergency department records. The clinical outcome was defined as the modified Rankin Scale (mRS) score at 90 days, which was dichotomized into favorable functional outcome (mRS 0-3) or unfavorable functional outcome (mRS 4-6). Multivariate logistic regression was used to build predictive models. A total of 53 patients were included. There were 26 patients in the favorable outcome group and 27 in the unfavorable outcome group. Age and platelet count (PC) were found to be predictors of unfavorable outcomes in the multivariate logistic regression analysis. The areas under the receiver operating characteristic (ROC) curve of models 1 (age only model), 2 (PC only model), and 3 (age and PC model) were 0.71, 0.68, and 0.79, respectively. This is the first study to reveal that elevated PC is an independent predictor of unfavorable outcomes in this specialized group.

Predictors of overlapping autoimmune disease in Neuromyelitis Optica Spectrum disorder (NMOSD): A retrospective analysis in two inner-city hospitals

BACKGROUND

The coexistence of Neuromyelitis Optica spectrum disorder (NMOSD) with other autoimmune diseases (AD-NMOSD) presents worse clinical outcomes and healthcare costs than NMOSD alone (NMOSD-only). NMOSD and other autoimmune diseases also have a higher prevalence and morbidity in Black. We aim to compare clinical features and treatment responses in NMOSD patients with and without overlapping autoimmunity in a predominantly Black cohort. We further identify predictors associated with each clinical subtype.

METHODS

AD-NMOSD (n = 14) and NMOSD-only (n = 27) patients were identified retrospectively. Demographic, clinical, laboratory, imaging, and response to treatment data were examined.

RESULTS

Our cohort was predominately Black (82.9%). The prevalence of grouped-comorbidities, history of infections, sensory symptoms, Expanded Disability Status Scale (EDSS) before treatment, double-stranded DNA, antinuclear, ribonucleoprotein, and antiphospholipid antibodies, spinal-cord edema, white matter occipital lesions, and the levels of C-reactive protein, urine protein/creatinine, white blood cell count in cerebrospinal fluid (CSF), were higher in AD-NMOSD patients (p < 0.05 and/or Cramer's V > 30, Cohen's d > 50), whereas the age of males, visual symptoms, serum albumin, platelet count, and optic nerve enhancement were lower. EDSS after treatment improved in both groups being more evident in NMOSD-only patients (p = 0.003, SE = 0.58 vs p = 0.075, SE = 0.51). Other variables had a close to moderate SE, and others did not differ between NMOSD subtypes. A higher frequency of grouped-comorbidities, lower serum albumin, and platelet count were independently associated with a higher risk for AD-NMOSD.

CONCLUSIONS

Some clinical features between AD-NMOSD and NMOSD-only patients were similar, while others differed. Comorbidities, serum albumin, and platelet count may be independent predictors of AD-NMOSD.

Inflammatory platelet production stimulated by tyrosyl-tRNA synthetase mimicking viral infection

Platelets play a role not only in hemostasis and thrombosis, but also in inflammation and innate immunity. We previously reported that an activated form of tyrosyl-tRNA synthetase (YRSACT) has an extratranslational activity that enhances megakaryopoiesis and platelet production in mice. Here, we report that YRSACT mimics inflammatory stress inducing a unique megakaryocyte (MK) population with stem cell (Sca1) and myeloid (F4/80) markers through a mechanism dependent on Toll-like receptor (TLR) activation and type I interferon (IFN-I) signaling. This mimicry of inflammatory stress by YRSACT was studied in mice infected by lymphocytic choriomeningitis virus (LCMV). Using Sca1/EGFP transgenic mice, we demonstrated that IFN-I induced by YRSACT or LCMV infection suppressed normal hematopoiesis while activating an alternative pathway of thrombopoiesis. Platelets of inflammatory origin (Sca1/EGFP+) were a relevant proportion of those circulating during recovery from thrombocytopenia. Analysis of these "inflammatory" MKs and platelets suggested their origin in myeloid/MK-biased hematopoietic stem cells (HSCs) that bypassed the classical MK-erythroid progenitor (MEP) pathway to replenish platelets and promote recovery from thrombocytopenia. Notably, inflammatory platelets displayed enhanced agonist-induced activation and procoagulant activities. Moreover, myeloid/MK-biased progenitors and MKs were mobilized from the bone marrow, as evidenced by their presence in the lung microvasculature within fibrin-containing microthrombi. Our results define the function of YRSACT in platelet generation and contribute to elucidate platelet alterations in number and function during viral infection.

Potential Cross Talk between Autism Risk Genes and Neurovascular Molecules: A Pilot Study on Impact of Blood Brain Barrier Integrity

Autism Spectrum Disorder (ASD) is a common pediatric neurobiological disorder with up to 80% of genetic etiologies. Systems biology approaches may make it possible to test novel therapeutic strategies targeting molecular pathways to alleviate ASD symptoms. A clinical database of autism subjects was queried for individuals with a copy number variation (CNV) on microarray, Vineland, and Parent Concern Questionnaire scores. Pathway analyses of genes from pathogenic CNVs yielded 659 genes whose protein-protein interactions and mRNA expression mapped 121 genes with maximal antenatal expression in 12 brain regions. A Research Domain Criteria (RDoC)-derived neural circuits map revealed significant differences in anxiety, motor, and activities of daily living skills scores between altered CNV genes and normal microarrays subjects, involving Positive Valence (reward), Cognition (IQ), and Social Processes. Vascular signaling was identified as a biological process that may influence these neural circuits. Neuroinflammation, microglial activation, iNOS and 3-nitrotyrosine increase in the brain of Semaphorin 3F- Neuropilin 2 (Sema 3F-NRP2) KO, an ASD mouse model, agree with previous reports in the brain of ASD individuals. Signs of platelet deposition, activation, release of serotonin, and albumin leakage in ASD-relevant brain regions suggest possible blood brain barrier (BBB) deficits. Disruption of neurovascular signaling and BBB with neuroinflammation may mediate causative pathophysiology in some ASD subgroups. Although preliminary, these data demonstrate the potential for developing novel therapeutic strategies based on clinically derived data, genomics, cognitive neuroscience, and basic neuroscience methods.

Deletion of the Pedf gene leads to inflammation, photoreceptor loss and vascular disturbances in the retina

Retinal diseases are often accompanied by inflammation, vascular abnormalities, and neurodegeneration that decrease vision. Treatment with exogenous PEDF is widely shown to alleviate these conditions leading us to hypothesize that loss of function of the PEDF gene disrupts these pathways and leads to visual loss. Measurements were carried out by detailed phenotyping of PEDF null mice to assess expression of immunomodulators, glia activation, systemic inflammation, vascular disturbances, and visual sensitivity often associated with retinal pathologies. With a deletion of the Pedf gene, there was increased expression of several immune modulators in Pedf^-/- retinas and serum with IL-2 and GM-CSF upregulated in both. Increases in retina glia activation and macrophage infiltration, levels of serum c-reactive protein (CRP), numbers of white and red blood cells and platelets and decreased blood glucose levels were all features associated with PEDF null mice. With PEDF gene deletion, there was also a notable increase in apoptosis in early developing retinas (PN3), reduced thickness of the photoreceptor layer, swelling of the inner plexiform layer, reduced retinal sensitivity and steady-state reduced activation of Erk and Akt, two signaling pathways used by PEDF. There is a substantial body of animal data emphasizing utility of PEDF treatment in homeostatic regulation of retinal diseases, including diabetic retinopathy and age-related macular degeneration but there is little agreement or evidence on the role of endogenous PEDF in retinal diseases. Our findings strongly support the concept that a deletion of the PEDF gene makes the retina vulnerable to diseases, and argue that endogenous PEDF plays a critical role in limiting pathological events in the retina.

Dengue Infection - Recent Advances in Disease Pathogenesis in the Era of COVID-19

The dynamics of host-virus interactions, and impairment of the host’s immune surveillance by dengue virus (DENV) serotypes largely remain ambiguous. Several experimental and preclinical studies have demonstrated how the virus brings about severe disease by activating immune cells and other key elements of the inflammatory cascade. Plasmablasts are activated during primary and secondary infections, and play a determinative role in severe dengue. The cross-reactivity of DENV immune responses with other flaviviruses can have implications both for cross-protection and severity of disease. The consequences of a cross-reactivity between DENV and anti-SARS-CoV-2 responses are highly relevant in endemic areas. Here, we review the latest progress in the understanding of dengue immunopathogenesis and provide suggestions to the development of target strategies against dengue.

Testosterone-to-estradiol ratio and platelet thromboxane release in ischemic heart disease: the EVA project

BACKGROUND

Data on the interplay between sexual hormones balance, platelet function and clinical outcomes of adults with ischemic heart disease (IHD) are still lacking.

OBJECTIVE

To assess the association between the Testosterone (T)-to-Estradiol (E2) Ratio (T/E2) and platelet activation biomarkers in IHD and its predictive value on adverse outcomes.

METHODS

The EVA study is a prospective observational study of consecutive hospitalized adults with IHD undergoing coronary angiography and/or percutaneous coronary interventions. Serum T/E2 ratios E2, levels of thromboxane B₂ (TxB₂) and nitrates (NO), were measured at admission and major adverse events, including all-cause mortality, were collected during a long-term follow-up.

RESULTS

Among 509 adults with IHD (mean age 67 ± 11 years, 30% females), males were older with a more adverse cluster of cardiovascular risk factors than females. Acute coronary syndrome and non-obstructive coronary artery disease were more prevalent in females versus males. The lower sex-specific T/E2 ratios identified adults with the highest level of serum TxB₂ and the lowest NO levels. During a median follow-up of 23.7 months, the lower sex-specific T/E2 was associated with higher all-cause mortality (HR 3.49; 95% CI 1.24-9.80; p = 0.018). In in vitro, platelets incubated with T/E2 ratios comparable to those measured in vivo in the lowest quartile showed increased platelet activation as indicated by higher levels of aggregation and TxB₂ production.

CONCLUSION

Among adults with IHD, higher T/E2 ratio was associated with a lower long-term risk of fatal events. The effect of sex hormones on the platelet thromboxane release may partially explain such finding.

Coagulation Parameters in Human Immunodeficiency Virus Infected Patients: A Systematic Review and Meta-Analysis

Background

Coagulation abnormalities are common complications of human immunodeficiency virus (HIV) infection. Highly active antiretroviral treatment (HAART) decreased the mortality of HIV but increased coagulopathies. HIV-related thrombocytopenia, prolonged prothrombin time (PT), activated partial thromboplastin time (APTT), and high D-dimer level commonly manifested in patients with HIV. Thus, this study is aimed to compare coagulation parameters of HAART-treated and HAART-naïve HIV-infected patients with HIV-seronegative controls.

Methods

A systematic literature search was conducted using the databases PubMed/MEDLINE, Embase, Web of Science, and Google Scholar of studies published until July 2021. The primary outcome of interest was determining the pooled mean difference of coagulation parameters between HIV-infected patients and seronegative controls. The Joana Briggs Institute (JBI) critical appraisal tool was used for quality appraisal. Statistical analyses were performed using Stata11.0 software. The statistical results were expressed as the effect measured by standardized mean difference (SMD) with their related 95% confidence interval (CI).

Results

A total of 7,498 participants (1,144 HAART-naïve patients and 2,270 HAART-treated HIV-infected patients and 3,584 HIV-seronegative controls) from 18 studies were included. HIV-infected patients (both on HAART and HAART-naive) exhibited significantly higher levels of PT than HIV-seronegative controls (SMD = 0.66; 95% CI: 0.53–0.80 and SMD = 1.13; 95% CI: 0.60–2.0, respectively). The value of APTT was significantly higher in patients with HIV on HAART than in seronegative controls. However, the values of PLT count, APTT, and fibrinogen level were significantly higher in seronegative controls. Besides, the level of fibrinogen was significantly higher in HAART-treated than treatment-naïve patients (SMD = 0.32; 95%CI: 0.08, 0.57). Moreover, the level of APTT and PT had no statistical difference between HAART and HAART-naïve HIV-infected patients.

Conclusions

This study identified that HIV-infected patients are more likely to develop coagulation abnormalities than HIV-seronegative controls. Therefore, coagulation parameters should be assessed regularly to prevent and monitor coagulation disorders in HIV-infected patients.

The Association between Influenza Vaccination and Stroke Risk in Patients with Hypertension: A Nationwide Population-Based Study

There is evidence of strong association between influenza infections and stroke; however, the influenza vaccination and its effect on strokes is currently unclear. In the present study, Taiwan’s National Health Insurance Database was used in obtaining data for study subjects 55 years and older diagnosed with hypertension (n = 59,251; 25,266 vaccinated and 33,985 unvaccinated subjects) from 2001–2012. Propensity scores were calculated using a logistic regression model to determine the effects of vaccination by accounting for covariates that predict receiving the intervention (vaccine). A time-dependent Cox proportional hazard model was used to calculate the hazard ratios (HRs) for stroke in vaccinated and unvaccinated patients. Influenza vaccination was associated with a 42%, 40% and 44% stroke risk reduction in the entire cohort for all seasons, the influenza season and the non-influenza season, respectively (Adjust hazard ratio [aHR]: 0.58, 95% confidence interval [CI]: 0.56–0.61; aHR: 0.60, 95% CI: 0.56–0.63; aHR: 0.56, 95% CI: 0.52–0.60, for all seasons, the influenza season and the non-influenza season, respectively). The effect of risk reduction by vaccination also revealed a trend of dose dependency. Among subjects between 55 to 64 years old with four or more vaccinations during the study period, there is a 73% risk reduction for stroke during the non-influenza season (aHR: 0.27, 95% CI: 0.20–0.34). In conclusion, the influenza vaccination exerts dose-dependent and synergistic protective effects against stroke in individuals 55 years and older with hypertension.

25-Hydroxy vitamin D level is associated with mean platelet volume in patients with acute coronary syndrome

BACKGROUND AND AIMS

A better identification of the role of vitamin D in the thrombotic process of acute coronary syndrome (ACS) will help increase the therapeutic options for this important clinical condition. There is little published evidence that 25-hydroxy vitamin D (25(OH)D) serum levels can associate with platelet function and risk of thrombosis.

MATERIALS AND METHODS

This prospective study was conducted on 200 patients with a diagnosis of ACS, including patients with unstable angina (UA), non-ST segment elevation myocardial infarction (NSTEMI), and ST segment elevation myocardial infarction (STEMI). In addition to demographics and angiographic data, serum concentrations of 25(OH)D and MPV were recorded in all patients.

RESULTS

The types of ACS were STEMI (35%), NSTEMI (25%), and UA (40%). The concentrations of 25(OH)D in patients with UA, NSTEMI, and STEMI were 23.53 ± 13.26, 19.25 ± 8.09 and 14.60 ± 8.24 ng/mL respectively (P < 0.001), and the values of MPV were 9.83 ± 1.35, 10.30 ± 1.21, and 11.56 ± 1.38 fL, respectively (P < 0.001). There was a negative correlation between 25(OH)D and MPV (R = -0.320, P < 0.0001). ROC analysis illustrated a moderate predictive value (AUC 0.706; 95% CI, 0.63-0.72) in identifying the discrimination threshold of MPV (≥ 9.90 fL) for vitamin D deficiency (<20 ng/mL).

CONCLUSION

The current study shows an inverse association between MPV and vitamin D levels in ACS patients, especially in the subgroup of STEMI. These findings propose the effect of vitamin D on platelet size and function, suggesting its role in thrombosis and hemostasis, which might explain the link between vitamin D deficiency and cardiovascular diseases.

Advances and Challenges in Biomarkers Use for Coronary Microvascular Dysfunction: From Bench to Clinical Practice

Coronary microvascular dysfunction (CMD) is related to a broad variety of clinical scenarios in which cardiac microvasculature is morphologically and functionally affected, and it is associated with impaired responses to vasoactive stimuli. Although the prevalence of CMD involves about half of all patients with chronic coronary syndromes and more than 20% of those with acute coronary syndrome, the diagnosis of CMD is often missed, leading to the underestimation of its clinical importance. The established and validated techniques for the measurement of coronary microvascular function are invasive and expensive. An ideal method to assess endothelial dysfunction should be accurate, non-invasive, cost-effective and accessible. There are varieties of biomarkers available, potentially involved in microvascular disease, but none have been extensively validated in this heterogeneous clinical population. The investigation of potential biomarkers linked to microvascular dysfunction might improve the assessment of the diagnosis, risk stratification, disease progression and therapy response. This review article offers an update about traditional and novel potential biomarkers linked to CMD.

Endothelial Transcytosis in Acute Lung Injury: Emerging Mechanisms and Therapeutic Approaches

Acute Lung Injury (ALI) is characterized by widespread inflammation which in its severe form, Acute Respiratory Distress Syndrome (ARDS), leads to compromise in respiration causing hypoxemia and death in a substantial number of affected individuals. Loss of endothelial barrier integrity, pneumocyte necrosis, and circulating leukocyte recruitment into the injured lung are recognized mechanisms that contribute to the progression of ALI/ARDS. Additionally, damage to the pulmonary microvasculature by Gram-negative and positive bacteria or viruses (e.g., Escherichia coli, SARS-Cov-2) leads to increased protein and fluid permeability and interstitial edema, further impairing lung function. While most of the vascular leakage is attributed to loss of inter-endothelial junctional integrity, studies in animal models suggest that transendothelial transport of protein through caveolar vesicles, known as transcytosis, occurs in the early phase of ALI/ARDS. Here, we discuss the role of transcytosis in healthy and injured endothelium and highlight recent studies that have contributed to our understanding of the process during ALI/ARDS. We also cover potential approaches that utilize caveolar transport to deliver therapeutics to the lungs which may prevent further injury or improve recovery.

Investigation of Platelet Aggregation in Atherosclerosis

Platelet activation and aggregation is implicated in all stages of inflammation-related atherosclerosis from the initial steps of endothelial dysfunction and plaque formation, to plaque rupture and atherothrombotic events, such as acute coronary syndrome, myocardial infarction, and ischemic incidences. Platelet aggregometry assays are the mainstream for evaluating and monitoring platelet reactivity in such conditions and for the investigation of prophylactic and therapeutic approaches. The most established methodology is light transmittance aggregometry (LTA). Here we describe the appropriate preparation of platelet suspensions from human blood and the methodology of LTA-based assays that is used for basic and clinical research for monitoring and evaluating the activities of several thrombotic mediators, as well as determining the dose efficacy and safety of several pharmaceutical and nutraceutical compounds intended for therapeutic and prophylactic interventions for atherosclerosis.

Targeting repair of the vascular endothelium and glycocalyx after traumatic injury with plasma and platelet resuscitation

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Endothelial glycocalyx shedding is a key instigator of the endotheliopathy of trauma.

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Plasma and platelet transfusions preserve vascular integrity in pre-clinical models.

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However, platelets may be less effective than plasma in preserving the glycocalyx.

Severely injured patients with hemorrhagic shock can develop endothelial dysfunction, systemic inflammation, and coagulation disturbances collectively known as the endotheliopathy of trauma (EOT). Shedding of the endothelial glycocalyx occurs early after injury, contributes to breakdown of the vascular barrier, and plays a critical role in the pathogenesis of multiple organ dysfunction, leading to poor outcomes in trauma patients. In this review we discuss (i) the pathophysiology of endothelial glycocalyx and vascular barrier breakdown following hemorrhagic shock and trauma, and (ii) the role of plasma and platelet transfusion in maintaining the glycocalyx and vascular endothelial integrity.

Dynamic platelet function: A novel biomarker in inflammatory arthritis?

Background

Patients with inflammatory arthritis die prematurely of cardiovascular disease. Inflammation activates platelets. Since treatment of inflammatory arthritis is associated with reduced mortality, and decreased platelet reactivity reduces cardiovascular events, we hypothesised that platelet reactivity as measured by dynamic platelet function (DPF) would be increased in patients with inflammatory arthritis and that reactivity could be reduced with therapeutic intervention.

Objectives

To characterise platelet function using a validated physiological assay in patients with inflammatory arthritis before and after disease improvement.

Methods

22 patients were recruited and treated as per local protocol. DPF was measured at baseline and after clinical improvement. Video microscopy was utilised to measure dynamic platelet behaviour in microliters of blood perfused over von Willebrand factor (VWF) at arterial shear rates (1500 s-1). Motion-analysis software measured the number of platelets interacting with VWF, translocating across VWF, the speed and distance platelets travelled across VWF, and stably adhering to the surface. Platelet parameters at baseline and following improvement were compared using Wilcoxon signed rank test and paired student t-test. Changes in platelet function were correlated to inflammatory disease markers by Pearson Correlation.

Results

18 patients completed the study. Platelet adhesion decreased and platelet motion increased following treatment. Tender joint count correlated with platelet adhesion (Pearson r = 0.616, p≤0.01) while CRP correlated with velocity of platelet movement (Pearson r = 0.563, p≤0.01).

Conclusions

Improvement in clinical markers of inflammation is associated with a corresponding change in platelet function. Given the association between reduced mortality and decreased platelet reactivity our results suggest that an appropriate assay of platelet function could guide future therapy of patients with inflammatory arthritis.

Thrombocytopenia predicts mortality in Chinese hemodialysis patients- an analysis of the China DOPPS

BACKGROUND

Hemodialysis (HD) patients have a higher mortality rate compared with general population. Our previous study revealed that platelet counts might be a potential risk factor. The role of platelets in HD patients has rarely been studied. The aim of this study is to examine if there is an association of thrombocytopenia (TP) with elevated risk of all-cause mortality and cardiovascular (CV) death in Chinese HD patients.

METHODS

Data from a prospective cohort study, China Dialysis Outcomes and Practice Patterns Study (DOPPS) 5, were analyzed. Demographic data, comorbidities, platelet counts and other lab data, and death records which extracted from the medical record were analyzed. TP was defined as the platelet count below the lower normal limit (< 100*109/L). Associations between platelet counts and all-cause and CV mortality were evaluated using Cox regression models. Stepwise multivariate logistic regression was used to identify the independent associated factors, and subgroup analyses were also carried out.

RESULTS

Of 1369 patients, 11.2% (154) had TP at enrollment. The all-cause mortality rates were 26.0% vs. 13.3% (p < 0.001) in patients with and without TP. TP was associated with higher all-cause mortality after adjusted for covariates (HR:1.73,95%CI:1.11,2.71), but was not associated with CV death after fully adjusted (HR:1.71,95%CI:0.88,3.33). Multivariate logistic regression showed that urine output < 200 ml/day, cerebrovascular disease, hepatitis (B or C), and white blood cells were independent impact factors (P < 0.05). Subgroup analysis found that the effect of TP on all-cause mortality was more prominent in patients with diabetes or hypertension, who on dialysis thrice a week, with lower ALB (< 4 g/dl) or higher hemoglobin, and patients without congestive heart failure, cerebrovascular disease, or hepatitis (P < 0.05).

CONCLUSION

In Chinese HD patients, TP is associated with higher risk of all-cause mortality, but not cardiovascular mortality. Platelet counts may be a useful prognostic marker for clinical outcomes among HD patients, though additional study is needed.

Chronic Thrombocytopenia and In-Hospital Outcomes After Primary Total Hip and Knee Arthroplasty

BACKGROUND

There is a lack of data on the influence of chronic thrombocytopenia (cTCP) on clinical outcomes following primary total hip arthroplasty (THA) and total knee arthroplasty (TKA). Limited studies mainly focused on postoperative heparin-induced TCP from single centers with small sample sizes. This study aims to describe the characteristics, trend, and outcomes of cTCP in patients undergoing THA and TKA from a nationally reprehensive perspective.

METHODS

We identified THA and TKA patients with and without cTCP from the 2005 to 2015 Nationwide Inpatient Sample. Annual percent changes were calculated to reflect cTCP trends. Multivariable regression and propensity score analyses were conducted to investigate the association of cTCP and mortality, preoperative complications, cost as well as length of stay.

RESULTS

In total, 578,278 and 1,237,331 patients underwent primary THA and TKA, respectively. Proportion of cTCP annually increased by 6.95% in THA and 6.66% in TKA. Patients with cTCP were associated with higher risk of medical (odds ratio [OR] 2.00, 95% confidence interval [CI] 1.89-2.11) and surgical complications (OR 2.72, 95% CI 2.55-2.90) in THA, and higher risk of mortality (OR 1.68, 95% CI 1.22-2.31), medical (OR 1.94, 95% CI 1.85-2.03) and surgical complications (OR 2.55, 95% CI 2.38-2.73) in TKA. Additionally, higher cost and longer length of stay were observed in patients with cTCP for both surgical procedures.

CONCLUSION

Patients with cTCP had higher risk of mortality for TKA, more perioperative complications for both TKA and THA. Further studies are warranted to improve the preoperative management and to prevent worse outcomes associated with cTCP.

Comparison of intra-articular administration of adenosine, lidocaine and magnesium solution and tranexamic acid for alleviating postoperative inflammation and joint fibrosis in an experimental model of knee arthroplasty

BACKGROUND

Dysregulated inflammatory responses are implicated in the pathogenesis of joint stiffness and arthrofibrosis following total knee arthroplasty (TKA). The purpose of this study was to compare the effects of intra-articular (IA) administration of tranexamic acid (TXA), an anti-fibrinolytic commonly used in TKA, and ALM chondroprotective solution on postoperative inflammation and joint tissue healing in a rat model of knee implant surgery.

METHODS

Male Sprague-Dawley rats (n = 24) were randomly divided into TXA or ALM treatment groups. The right knee of each rat was implanted with titanium (femur) and polyethylene (tibia) implants. An IA bolus (0.1 ml) of TXA or ALM was administered after implantation and capsule closure, and before skin closure. Postoperative coagulopathy, haematology and systemic inflammatory changes were assessed. Inflammatory and fibrotic markers were assessed in joint tissue, 28 days after surgery.

RESULTS

Haemostasis was comparable in animals treated with TXA or ALM after knee implant surgery. In contrast to ALM-treated animals, systemic inflammatory markers remained elevated at day 5 (IL-6, IL-12, IL-10, platelet count) and day 28 (IL-1β, IL-10) following surgery in TXA-treated animals. At day 28 following surgery, the extension range of motion of operated knees was 1.7-fold higher for ALM-treated animals compared to the TXA group. Key inflammatory mediators (NF-κB, IL-12, IL-2), immune cell infiltration (CD68+ cells) and markers of fibrosis (α-SMA, TGF-β) were also lower in capsular tissue of ALM-treated knees at day 28.

CONCLUSION

Data suggest that IA administration of ALM is superior to TXA for reducing postoperative systemic and joint inflammation and promoting restoration of healthy joint tissue architecture in a rat model of TKA. Further studies are warranted to assess the clinical translational potential of ALM IA solution to improve patient outcomes following arthroplasty.

Hematological parameters as a predictor of disease remission in patients with rheumatoid arthritis

Background

Alterations in the hematological profile have been linked to disease activity in rheumatoid arthritis (RA). We aimed to evaluate the levels of hematological parameters in different phases of rheumatoid arthritis (RA) and determine whether hematological parameters could be used to predict RA remission.

Materials and methods

The medical records of 365 RA patients were reviewed. Multivariate logistic regression analysis was used to compare hematological parameters among RA patients who were categorized into 4 groups according to disease activity: disease remission or low, moderate or high disease activity. Receiver operating characteristic curves were used to determine the predictive performances of significant parameters for RA remission.

Results

Complete data were obtained from 325 patients. The 4 groups of patients had different levels of hemoglobin (Hb), red blood cell, white blood cell, and platelet values. In multivariate analysis, Hb level, neutrophil-to-lymphocyte ratio (NLR), and mean platelet volume (MPV) were independent factors associated with disease activity. The combination of these 3 parameters yielded a sensitivity of 95.2% (95% confidence interval [CI] 88.7-98.2), specificity of 23.6% (95% CI 18.3-29.9), positive predictive value of 37.3% (95% CI 31.6-43.4), and negative predictive value of 91.2% (95% CI 80.0-96.7) in predicting disease remission.

Conclusion

Hb level, NLR and MPV were independently associated with RA disease activity. The high sensitivity and negative predictive value of the model consisting of Hb level, NLR and MPV may serve as a simple and inexpensive tool to identify patients who are less likely to have disease remission.

The posttraumatic response of CD4+ regulatory T cells is modulated by direct cell-cell contact via CD40L- and P-selectin-dependent pathways

CD4+ FoxP3+ regulatory T cells (CD4+ Tregs) are important for the posttraumatic anti-inflammatory host response. As described previously, platelets are able to modulate CD4+ Treg activity in a reciprocally activating interaction following injury. The underlying mechanisms of the posttraumatic interaction between platelets and CD4+ Tregs remain unclear. We investigated the potential influence of CD40L and P-selectin, molecules known to be involved in direct cell contact of these cell types. In a murine burn injury model, the potential interaction pathways were addressed using CD40L- and P-selectin-deficient mice. Draining lymph nodes were harvested following trauma (1 h) and following a sham procedure. Early rapid activation of CD4+ Tregs was assessed by phospho-flow cytometry (signaling molecules (p)PKC-δ and (p)ZAP-70). Platelet function was analyzed performing rotational thromboelastometry (ROTEM). We hypothesized that disruption of the direct cell-cell contact via CD40L and P-selectin would affect posttraumatic activation of CD4+ Tregs and influence the hemostatic function of platelets. Indeed, while injury induced early activation of CD4+ Tregs in wild-type mice (ZAP-70: p = 0.13, pZAP-70: p < 0.05, PKC-δ: p < 0.05, pPKC-δ: p < 0.05), disruption of CD40L-dependent interaction (ZAP-70: p = 0.57, pZAP-70: p = 0.68, PKC-δ: p = 0.68, pPKC-δ: p = 0.9) or P-selectin-dependent interaction (ZAP-70: p = 0.78, pZAP-70: p = 0.58, PKC-δ: p = 0.81, pPKC-δ: p = 0.73) resulted in reduced posttraumatic activation. Furthermore, hemostatic function was impaired towards hypocoagulability in either deficiency. Our results suggest that the posttraumatic activation of CD4+ Tregs and hemostatic function of platelets are affected by direct cell-cell-signaling via CD40L and P-selectin.

Intravital assessment of precapillary pulmonary arterioles of type 1 diabetic mice shows oxidative damage and increased tone in response to NOS inhibition

Microvascular dilation, important for peripheral tissue glucose distribution, also modulates alveolar perfusion and is inhibited by loss of bioavailable nitric oxide (NO) in diabetes mellitus (DM). We hypothesized that DM-induced oxidative stress decreases bioavailable NO and pulmonary precapillary arteriolar diameter, causing endothelial injury. We examined subpleural pulmonary arterioles after acute NO synthase (NOS) inhibition with NG-nitro-l-arginine methyl ester (l-NAME) in streptozotocin (STZ)- and saline (CTRL)-treated C57BL/6J mice. Microvascular changes were assessed by intravital microscopy in the right lung of anesthetized mice with open chest and ventilated lungs. Arteriolar tone in pulmonary arterioles (27.2-48.7 µm diameter) increased in CTRL mice (18.0 ± 11% constriction, P = 0.034, n = 5) but decreased in STZ mice (13.6 ± 7.5% dilation, P = 0.009, n = 5) after l-NAME. Lung tissue dihydroethidium (DHE) fluorescence (superoxide), inducible NOS expression, and protein nitrosylation (3-nitrotyrosine) increased in STZ mice and correlated with increased glucose levels (103.8 ± 8.8 mg/dL). Fluorescently labeled fibrinogen administration and fibrinogen immunostaining showed fibrinogen adhesion, indicating endothelial injury in STZ mice. In CTRL mice, vasoconstriction to l-NAME was likely due to the loss of bioavailable NO. Vasodilation in STZ mice may be due to decreased formation of a vasoconstrictor or emergence of a vasodilator. These findings provide novel evidence that DM targets the pulmonary microcirculation and that decreased NO bioavailability and increased precapillary arteriolar tone could potentially lead to ventilation-perfusion abnormalities, exacerbating systemic DM complications.NEW & NOTEWORTHY Diabetes pulmonary and microvascular consequences are well recognized but have not been characterized. We assessed lung microvascular changes in a live anesthetized mouse model of type 1 diabetes, using a novel intravital microscopy technique. Our results show new evidence that a diabetes-induced decrease in lung nitric oxide bioavailability underlies oxidative damage, enhanced platelet activation, and endothelial injury causing pulmonary microvascular dysfunction and altered vasoreactivity. These findings could provide novel strategies to prevent or reverse diabetes systemic consequences.

NADPH oxidases regulate endothelial inflammatory injury induced by PM2.5 via AKT/eNOS/NO axis

Fine particulate matter (PM_2.5 )-induced detrimental cardiovascular effects have been widely concerned, especially for endothelial cells, which is the first barrier of the cardiovascular system. Among potential mechanisms involved, reactive oxidative species take up a crucial part. However, source of oxidative stress and its relationship with inflammatory response have been rarely studied in PM_2.5 -induced endothelial injury. Here, as a key oxidase that catalyzes redox reactions, NADPH oxidase (NOX) was investigated. Human umbilical vein endothelial cells (EA.hy926) were exposed to Standard Reference Material 1648a of urban PM_2.5 for 24 h, which resulted in NOX-sourced oxidative stress, endothelial dysfunction, and inflammation induction. These are manifested by the up-regulation of NOX, increase of superoxide anion and hydrogen peroxide, elevated endothelin-1 (ET-1) and asymmetric dimethylarginine (ADMA) level, reduced nitric oxide (NO) production, and down-regulation of phosphorylation of endothelial NO synthase (eNOS) with increased levels of inducible NO synthase, as well as the imbalance between tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1), and changes in the levels of pro-inflammatory and anti-inflammatory factors. However, administration of NOX1/4 inhibitor GKT137831 alleviated PM_2.5 -induced elevated endothelial dysfunction biomarkers (NO, ET-1, ADMA, iNOS, and tPA/PAI-1), inflammatory factors (IL-1β, IL-10, and IL-18), and adhesion molecules (ICAM-1, VCAM-1, and P-selectin) and also passivated NOX-dependent AKT and eNOS phosphorylation that involved in endothelial activation. In summary, PM_2.5 -induced NOX up-regulation is the source of ROS in EA.hy926, which activated AKT/eNOS/NO signal response leading to endothelial dysfunction and inflammatory damage in EA.hy926 cells.

Alterations in platelets during SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19) is a pandemic syndrome caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. SARS-CoV-2 infection induces a process of inflammation and thrombosis supported by an altered platelet activation state. This platelet activation is peculiar being characterized by the formation of platelet-leukocytes rather than platelet–platelet aggregates and by an increased procoagulant potential supported by elevated levels of TF positive platelets and microvesicles.

Therapeutic strategies targeting, beyond systemic inflammation (i.e. with tocilizumab, an anti interleukin-6 receptor), this state of platelet activation might therefore be beneficial. Among the antithrombotic drugs proposed as candidates to treat patients with SARS-CoV-2 infection, antiplatelet drugs, such as aspirin are showing promising results.

Deterioration of vaccine-induced immune thrombotic thrombocytopenia treated by heparin and platelet transfusion: Insight from functional cytometry and serotonin release assay

We report a case of a 62-year-old man who developed cerebral venous sinus thrombosis with subarachnoid hemorrhage and concomitant thrombocytopenia, which occurred 13 days after ChAdOx1 nCov-19 injection. The patient died in the intensive care unit after heparin infusion and platelet transfusion. The key clinical purpose of this case report is to better understand how to confirm vaccine-induced immune thrombotic thrombocytopenia (VITT). VITT diagnosis was made using 14C-serotonin release and flow cytometry evaluating activation and platelet microvesicles on washed platelets. Four control patients were examined: a patient with heparin-induced thrombocytopenia (HIT), two patients with thrombotic events without thrombocytopenia after ChAdOx1 nCov-19 or BNT162b2, and a patient with suspected HIT and an excluded diagnosis. We evidenced in the VITT case a high level of IgG anti-platelet factor 4-heparin antibodies associated with a high level of platelet activation in the absence of heparin. Conversely, the functional assays were negative in the patients with thrombosis without thrombocytopenia.

Clustering of blood cell count abnormalities and future risk of death

BACKGROUND

The identification of novel predictors of poor outcome may help stratify cardiovascular risk. Aim was to evaluate the individual contribution of blood cell count parameters, as well as their clustering, on the risk of death and cardiovascular events over the long term in the population-based Malmö Diet and Cancer Study cohort.

METHODS

In 30,447 individuals (age 57 ± 8 years), we assessed the incidence of all-cause death (primary endpoint) and major adverse cardiovascular events (MACE, secondary outcome measure) according to absence or presence of one, two and three factors at baseline out of the following: anaemia, leukocytosis and thrombocytosis. Median follow-up was 16 years.

RESULTS

The percentages of all-cause death were 19.5% in individuals without factors, 21.3% in those with one factor, 27.4% with two and 46.4% with three (log-rank test P < .001). The crude incidence of MACE was 28.0%, 29.2%, 35.5% and 57.1%, respectively (log-rank test P < .001). At multivariate analysis, we found a stepwise increase in overall mortality with increasing number of prevalent factors (one factor: HR 1.23, 95% CI 1.14-1.31, P < .001; two factors: 1.61, 1.37-1.89, P < .001; three factors: 2.69, 1.44-5.01, P = .002, vs no factor). Similar findings were observed for the incidence of MACE (one factor: adjusted HR 1.18, 95% CI 1.11-1.24, P < .001; two factors: 1.52, 1.33-1.76, P < .001; three factors: 2.03, 1.21-3.67, P < .001, vs no factor).

CONCLUSIONS

The easily assessable clustering of anaemia, leukocytosis and thrombocytosis heralds higher incidence of death and adverse cardiovascular events.

A Potential Role of Vitamin D on Platelet Leukocyte Aggregation and Pathological Events in Sepsis: An Updated Review

Vitamin D deficiency and sepsis are both significant global health problems. Insufficient vitamin D is considered to be a pathogenically relevant factor of sepsis-related deaths; however, a causal relationship has not yet been demonstrated. Recently, vitamin D has been an exciting field of research owing to the identification of vitamin D receptors on many extra skeletal tissues and cells, suggesting an unexpected role on body physiology, beyond its effects on bone homeostasis. However, while the role of vitamin D on bone health is widely understood and has been successfully translated into clinical applications and public health policies, recent evidence supporting its role in other physiological and pathological processes has not been fully established. In sepsis, there is an induction of local intracellular vitamin D activity by most immune cells, including lymphocytes, macrophages, neutrophils, and dendritic cells, as well as vascular endothelial cells, to ensure efficient clearance of infective microorganisms and mediate anti-inflammatory and tolerogenic effects. The literature suggests an association between low vitamin D levels and sepsis, but clinical trials have yielded contradictory results. A greater understanding of this role may improve disease management. This article reviews the available knowledge regarding vitamin D in immune function, emerging literature regarding the association between its deficiency and sepsis, as well as presenting its potential effect on platelet leukocyte aggregations (PLAs), a significant pathology in sepsis. It also summarizes clinical trials involving vitamin D supplementation during critical illness and sepsis and addresses the impact of relevant factors of sepsis pathogenesis on the efficacy of vitamin D supplementation, which could contribute to the reported inconsistencies. Looking ahead, further studies are required to uncover the possible modulatory relationship between vitamin D and sepsis to define better cut-offs for its levels, proper timing of its administration, and the optimum dosage for best management.

Evaluation of Neutrophil-to-Lymphocyte Ratio, Platelet-to-Lymphocyte Ratio, and C-Reactive Protein in Tension-Type Headache Patients

Objectives  A tension headache is the most common type of headache, and its causes are multifactorial. A relationship has been shown between migraine headaches and neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and C-reactive protein (CRP). In this study, we investigated the NLR, PLR, and serum CRP levels in frequent episodic tension-type headache (FETTH) and chronic tension-type headache (CTTH) patients.

Materials and Methods  This retrospective study included 64 patients with FETTH, 80 patients with CTTH, and 60 healthy controls who were followed up in the neurology clinic. Hematological parameters were compared between the patient and control groups.

Results  In CTTH patients, platelets, NLR, PLR, and CRP values were statistically higher than in FETTH patients and patients in the control group. In FETTH patients, the PLR value was higher than in patients in the control group, but there was no statistically significant difference in NLR and CRP values between FETTH patients and patients in the control group. Also, there was no correlation between these values and age and gender.

Conclusion  Increase platelet count might have an effect on tension-type headache pathophysiology. Systemic inflammation parameters were shown to be significantly higher in CTTH patients. More comprehensive studies are needed to evaluate the effect of systemic inflammation on the chronicity of tension headaches.

Hemodialysis exacerbates proteolytic imbalance and pro-fibrotic platelet dysfunction

Multi-organ fibrosis among end stage renal disease (ESRD) patients cannot be explained by uremia alone. Despite mitigation of thrombosis during hemodialysis (HD), subsequent platelet dysfunction and tissue dysregulation are less understood. We comprehensively profiled plasma and platelets from ESRD patients before and after HD to examine HD-modulation of platelets beyond thrombotic activation. Basal plasma levels of proteolytic regulators and fibrotic factors were elevated in ESRD patients compared to healthy controls, with isoform-specific changes during HD. Platelet lysate (PL) RNA transcripts for growth and coagulative factors were elevated post-HD, with upregulation correlated to HD vintage. Platelet secretome correlations to plasma factors reveal acutely induced pro-fibrotic platelet phenotypes in ESRD patients during HD characterized by preferentially enhanced proteolytic enzyme translation and secretion, platelet contribution to inflammatory response, and increasing platelet dysfunction with blood flow rate (BFR) and Vintage. Compensatory mechanisms of increased platelet growth factor synthesis with acute plasma matrix metalloproteinase (MMP) and tissue inhibitor of MMPs (TIMP) increases show short-term mode-switching between dialysis sessions leading to long-term pro-fibrotic bias. Chronic pro-fibrotic adaptation of platelet synthesis were observed through changes in differential secretory kinetics of heterogenous granule subtypes. We conclude that chronic and acute platelet responses to HD contribute to a pro-fibrotic milieu in ESRD.

Red blood cell distribution width-to-platelet ratio inversely correlates with indicators of disease activity status in rheumatoid arthritis patients

Introduction. Present study was performed to verify red blood cell distribution width-to-platelet ratio (RPR) level in rheumatoid arthritis (RA) patients and to examine its correlation with clinical and biochemical indicators of disease activity status.Methods. In this cross-sectional analytical study, 67 patients with RA and 34 age- and gender-matched healthy control subjects were enrolled. Based on the disease activity score 28-ESR (DAS28-ESR), RA patients were divided into subgroups: low disease activity (n = 20), moderate disease activity (n = 22) and high disease activity (n = 25). Laboratory tests included erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) concentration, platelet count (PLT), red blood cells count (RBC), red blood cells distribution width (RDW) and fibrinogen concentration. Statistical analyses were carried out using SPSS 13 software. Statistical significance was set at a p-value less than 0.05.Results. There was statistically significant difference (p = 0.006) between RPR in RA patients with different stages of disease activity, with higher values in patients with low disease activity. The RPR showed statistically significant negative correlations with ESR (rho = -0.309; p = 0.012), CRP (rho = -0.421; p = 0.001), swollen joint count - SJC (rho = -0.368; p = 0.002) and tender joint count - TJC (rho = -0.355; p = 0.003), DAS28-ESR (rho = -0.409; p = 0.001), DAS28-CRP (rho = -0.422; p < 0.0005) and Visual analogue scale - VAS (rho = -0.260; p = 0.033) in RA patients.Conclusion. The present study provided evidence that the lower RPR values in RA patients are significantly associated with the disease activity indicators.