Oxidative stress and defective platelet apoptosis in naïve patients with Kawasaki disease

Phytochemicals profiling of Cassia fistula fruit extract and its effect on serum lipids and hematological parameters in high-fat diet-induced hyperlipidemic female rats

Cassia fistula (C. fistula) has shown strong anti-inflammatory, hepatoprotective, antitussive, antibacterial, and antifungal properties and is being used for healing wounds and gastrointestinal illness. This study was planned to obtain fruit extract from C. fistula using ultrasonic-assisted extraction (UAE) technique and evaluated for phytochemical contents, anti-hyperlipidemia, and hematological parameters. The results showed that total phenolic (TPC), total flavonoids (TFC), condensed tannin (CT), and saponins were 13.07 mg GAE/g, 5.24 mg QE/g, 4.01 mg/g, and 27.55%, respectively, in the extract. Proximate composition of the extract showed 2.48%, moisture, 1.25% fat, 2.80% ash, 4.59% fiber, 11.93% protein, and 76.95% NFE. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power assay (FRAP) activity was 63.30 μg/mL and 15.02 nmol/g, respectively. High-fat diet (HFD)-induced hyperlipidemic rats were orally administrated with 0.5 and 1.0 g of extract/kg body weight (bw) daily. The reduction of total cholesterol (TC: 90.83 ± 8.86 mg/dL), triglycerides (TG; 74.16 ± 9.10 mg/dL), and low-density lipoproteins (LDL; 74.83 ± 4.66 mg/dL) and increase of high-density lipoproteins (HDL; 41.83 ± 8.4 mg/dL) was observed. Significant changes in red blood cells (RBCs; 8.03 ± 0.67106/μL), mean corpuscular hemoglobin concentration (MCHC; 35.02 ± 1.78 g/dL), mean corpuscular hemoglobin (MCH; 18.00 ± 0.26 pg), and mean corpuscular volume (MCV; 55.36 ± 4.01 fL) at 1.0 g extract intake was observed. Extract administration also improved significantly liver enzymes, body weight, and liver morphology. Therefore, C. fistula extract can be effectively used as a therapeutic agent to improve serum biochemistry and hematological values.

Platelets in Kawasaki disease: mediators of vascular inflammation

Kawasaki disease, a systemic vasculitis that affects young children and can result in coronary artery aneurysms, is the leading cause of acquired heart disease among children. A hallmark of Kawasaki disease is increased blood platelet counts and platelet activation, which is associated with an increased risk of developing resistance to intravenous immunoglobulin and coronary artery aneurysms. Platelets and their releasate, including granules, microparticles, microRNAs and transcription factors, can influence innate immunity, enhance inflammation and contribute to vascular remodelling. Growing evidence indicates that platelets also interact with immune and non-immune cells to regulate inflammation. Platelets boost NLRP3 inflammasome activation and IL-1β production by human immune cells by releasing soluble mediators. Activated platelets form aggregates with leukocytes, such as monocytes and neutrophils, enhancing numerous functions of these cells and promoting thrombosis and inflammation. Leukocyte-platelet aggregates are increased in children with Kawasaki disease during the acute phase of the disease and can be used as biomarkers for disease severity. Here we review the role of platelets in Kawasaki disease and discuss progress in understanding the immune-effector role of platelets in amplifying inflammation related to Kawasaki disease vasculitis and therapeutic strategies targeting platelets or platelet-derived molecules.

Roles of Oxidative Injury and Nitric Oxide System Derangements in Kawasaki Disease Pathogenesis: A Systematic Review

Kawasaki disease (KD) is an acute febrile vasculitis that occurs mostly in children younger than five years. KD involves multiple intricately connected inflammatory reactions activated by a cytokine cascade. Despite therapeutic advances, coronary artery damage may develop in some patients, who will be at risk of clinical cardiovascular events and even sudden death. The etiology of KD remains unclear; however, it may involve both genetic and environmental factors leading to aberrant inflammatory responses. Given the young age of onset, prenatal or perinatal exposure may be etiologically relevant. Multisystem inflammatory syndrome in children, a post-infectious hyper-inflammatory disorder associated with severe acute respiratory syndrome coronavirus 2, has features that overlap with those of KD. Available evidence indicates that vascular endothelial dysfunction is a critical step in the sequence of events leading to the development of cardiovascular lesions in KD. Oxidative stress and the dysregulation of the nitric oxide (NO) system contribute to the pathogenesis of inflammatory responses related to this disease. This review provides current evidence and concepts highlighting the adverse effects of oxidative injury and NO system derangements on the initiation and progression of KD and potential therapeutic strategies for cardiovascular pathologies in affected children.

Platelets exacerbate cardiovascular inflammation in a murine model of Kawasaki disease vasculitis

Kawasaki disease (KD) is the leading cause of acquired heart disease among children. Increased platelet counts and activation are observed during the course of KD, and elevated platelet counts are associated with higher risks of developing intravenous immunoglobulin resistance and coronary artery aneurysms. However, the role of platelets in KD pathogenesis remains unclear. Here, we analyzed transcriptomics data generated from the whole blood of patients with KD and discovered changes in the expression of platelet-related genes during acute KD. In the Lactobacillus casei cell wall extract (LCWE) murine model of KD vasculitis, LCWE injection increased platelet counts and the formation of monocyte-platelet aggregates (MPAs), upregulated the concentration of soluble P-selectin, and increased circulating thrombopoietin and interleukin 6 (IL-6). Furthermore, platelet counts correlated with the severity of cardiovascular inflammation. Genetic depletion of platelets (Mpl-/- mice) or treatment with an anti-CD42b antibody significantly reduced LCWE-induced cardiovascular lesions. Furthermore, in the mouse model, platelets promoted vascular inflammation via the formation of MPAs, which likely amplified IL-1B production. Altogether, our results indicate that platelet activation exacerbates the development of cardiovascular lesions in a murine model of KD vasculitis. These findings enhance our understanding of KD vasculitis pathogenesis and highlight MPAs, which are known to enhance IL-1B production, as a potential therapeutic target for this disorder.

[Recent research on platelet-leukocyte aggregates and their role in the pathogenesis of Kawasaki disease]

Activated platelets may interact with various types of leukocytes such as monocytes, neutrophils, dendritic cells, and lymphocytes, trigger intercellular signal transduction, and thus lead to thrombosis and synthesis of massive inflammatory mediators. Elevated levels of circulating platelet-leukocyte aggregates have been found in patients with thrombotic or inflammatory diseases. This article reviews the latest research on the formation, function, and detection methods of platelet-leukocyte aggregates and their role in the onset of Kawasaki disease, so as to provide new ideas for studying the pathogenesis of Kawasaki disease.

Thymic stromal lymphopoietin induces platelet mitophagy and promotes thrombosis in Kawasaki disease

Kawasaki disease (KD) is an acute systemic vasculitis primarily affecting infants and children. Activated platelets predispose patients to coronary artery structural lesions that may lead to thrombotic cardiovascular events. To discover potential proteins underlying platelet activation in KD, we conducted a protein chip assay of 34 cytokines and discovered thymic stromal lymphopoietin (TSLP) was aberrantly expressed, which remained elevated after intravenous immunoglobulin G (IVIG) treatment and during convalescence in KD patients in comparison to healthy controls. Enzyme-linked immunosorbent assay (ELISA) corroborated the upregulation of TSLP in KD patients, which was exacerbated in convalescent patients complicated with thrombosis. TSLP receptors on platelets were also significantly upregulated in KD patients complicated with thrombosis. Platelet activation, apoptosis, and mitochondrial autophagy (mitophagy) were increased in convalescence KD patients complicated with thrombosis. In vitro, TSLP induced platelet activation and platelet mitophagy in healthy blood donors, as observed in KD patients. TSLP, similar to mitophagy agonist carbonyl cyanide 3-chlorophenyl hydrazone (CCCP), promoted thrombosis, which was attenuated by the mitophagy inhibitor Mdivi-1. Co-immunoprecipitation in TSLP-treated platelets revealed TSLP receptor (TSLPR) bound to mitophagy regulators, Parkin and Voltage Dependent Anion Channel Protein 1 (VDAC1).Thus, our results demonstrated that TSLP induced platelet mitophagy via a novel TSLPR/Parkin/VDAC1 pathway that promoted thrombosis in KD. These results suggest TSLP as a novel therapeutic target against KD-associated thrombosis.

Multisystem Inflammatory Syndrome in Children (MIS-C) Following SARS-CoV-2 Infection: Role of Oxidative Stress

With the appearance of the SARS-CoV-2 virus in December 2019, all countries in the world have implemented different strategies to prevent its spread and to intensively search for effective treatments. Initially, severe cases of the disease were considered in adult patients; however, cases of older school-age children and adolescents who presented fever, hypotension, severe abdominal pain and cardiac dysfunction, positive for SARS-CoV-2 infection, have been reported, with increased pro-inflammatory cytokines and tissue damage, condition denominated multisystemic inflammatory syndrome (MIS-C); The emerging data from patients with MIS-C have suggested unique characteristics in the immunological response and also clinical similarities with other inflammatory syndromes, which can support as a reference in the search for molecular mechanisms involved in MIS-C. We here in propose that oxidative stress (OE) may play a very important role in the pathophysiology of MIS-C, such as occurs in Kawasaki disease (KD), severe COVID-19 in adults and other processes with characteristics of vascular damage similar to MIS- C, for which we review the available information that can be correlated with possible redox mechanisms.

The relationship between TNF-like protein 1A and coronary artery aneurysms in children with Kawasaki disease

Kawasaki disease (KD) is an acute, systemic vasculitis of unknown etiology that occurs predominantly in infants and children, and the most crucial complication of KD is coronary artery aneurysm (CAA). Tumor necrosis factor (TNF)-like protein 1A (TL1A) is a member of the TNF superfamily, which possesses the ability of maintaining vascular homeostasis and regulating immune responses. This study aimed to examine serum TL1A levels in KD patients, and to investigate the relationship between TL1A and CAAs in children with KD. Blood samples were recruited from 119 KD patients, 35 febrile controls (FCs), and 37 healthy controls (HCs). The KD group was further divided into KD with CAAs (KD-CAAs) and KD non-CAAs (KD-NCAAs) groups. Serum TL1A levels were measured using enzyme-linked immunosorbent assays, and clinical parameters were collected from KD patients. Serum TL1A levels of KD patients in the acute phase of KD were significantly higher than in the FC and HC groups. In particular, serum TL1A levels were substantially increased in the KD-CAA group compared with the KD-NCAA group. Furthermore, TL1A levels in the KD group were positively correlated with the duration of fever and the time point of IVIG and WBC levels, but negatively correlated with levels of RBC, Hb and albumin. TL1A might be involved in KD-associated vasculitis and in the development of CAAs.

Sex differences in blood pro-oxidant status and platelet activation in children admitted with respiratory syncytial virus bronchiolitis: a pilot study

Background

Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis in the pediatric population worldwide and an important cause of death in developing countries. It has been demonstrated that the balance between oxidant and antioxidant systems is disrupted in children with bronchiolitis and that oxidative stress contributes to the pathogenesis of this disease. Platelets play an important role in antimicrobial host defenses and contribute to pulmonary vascular repair being either targets or source of reactive oxidizing species. The main purpose of this study was to assessing sex differences in clinical characteristics and platelets activation during RSV bronchiolitis in infancy.

Methods

In this retrospective study a total of 203 patients (112 boys and 91 girls) with bronchiolitis, aged 12 months or less, admitted to the Bambino Gesù Pediatric Hospital of Rome (Italy) in the period from January to December 2017, were enrolled. Moreover, in a select group of patients (15 boys and 12 girls) with diagnosis of moderate bronchiolitis from RSV, a pilot study on oxidative stress and platelet characteristics was carried out by electron paramagnetic resonance and flow cytometry respectively. Age-matched healthy control subjects (10 boys and 10 girls) were chosen as controls. Data were analyzed using Student’ T test, Chi Squared test and one-way ANOVA test.

Results

This study highlights the influence of sex in the clinical course of bronchiolitis. In particular we found: i) a higher incidence of bronchiolitis in boys than in girls (55% vs 45%); ii) higher C reactive protein values in girls than boys (1.11 mg/dL vs 0.92 mg/dL respectively; p < 0.05); iii) a different degree of thrombocytosis during hospitalization (mild in the girls and severe in the boys). Moreover, in selected patients we found that compared to girls with bronchiolitis, boys showed: i) higher percentage of activated platelets (8% vs 2% respectively; p < 0.05) and iii) higher number of platelets forming homotypic aggregates (2.36% vs 0.84% respectively, p < 0.05).

Conclusion

The present study affirm that the bronchiolitis is an infection in which sex seems to act as a modulating factor only in the clinical course, influencing also the choice of the therapy should be made.

Platelets in Kawasaki disease: Is this only a numbers game or something beyond?

Kawasaki disease (KD) is a medium vessel vasculitis with predilection to cause coronary artery abnormalities. KD is now the most common cause of acquired heart disease in developed countries. Thrombocytosis is consistently found in patients with KD, usually in 2nd to 3rd week of illness. Thrombocytopenia has occasionally been reported in the acute phase of KD. An increase or decrease in platelet number in patients with KD was initially considered to be a benign phenomenon. However, recent literature on platelet biology in KD has suggested that platelets are not only increasing but are rather activated. This phenomenon has been found to increase the risk of thrombosis in these patients. Similarly a fall in platelet counts during acute stage of KD has also been found to be associated with increased severity of disease. In this review, we update on the current best understanding about pathogenic role of platelets in patients with KD.

Single-nucleotide Polymorphism rs17860041 A/C in the Promoter of the PPIA Gene is Associated with Susceptibility to Kawasaki Disease in Chinese Children

Background: Kawasaki disease (KD) is an acute systemic vasculitis of unknown etiology. Cyclophilin A (CypA), also known as PPIA, has been identified to play a vital role in the pathogenesis of cardiovascular or inflammatory diseases. However, no studies have examined the relationship between single-nucleotide polymorphisms (SNPs) in the peptidylprolyl isomerase A (PPIA) and the development of KD and KD with or without coronary artery lesions (CALs). Objective: The present study was conducted to evaluate whether PPIA SNPs are associated with susceptibility to KD or CALs in KD. Methods: Three PPIA SNPs were genotyped in 101 KD patients and 105 healthy controls from a Chinese population. The allele and genotype frequencies were compared between the case and control groups, as well as in KD patients with and without CALs. Results: The data revealed a significant difference in the genotype and allele frequencies of rs17860041 A/C between KD patients and normal controls. Compared to the rs17860041 CC genotype, the AC genotype demonstrated a consistently beneficial roles in reducing the KD incidence. Furthermore, the allele frequency of C in the KD group was higher than that in the control group (P < .05). Haplotype analysis for PPIA polymorphisms (rs10951772 A/G, rs17860041 A/C, and rs4720485 A/T) also confirmed this association in KD patients and normal controls. Conclusion: A PPIA promoter SNP (rs17860041 A/C) confers susceptibility to KD in Chinese children and was identified as an important marker of KD in this study.

Elevated Levels of Pentraxin 3 Correlate With Neutrophilia and Coronary Artery Dilation During Acute Kawasaki Disease

Kawasaki disease (KD) is the leading cause of acquired pediatric heart disease in the developed world as 25-30% of untreated patients and at least 5% of treated patients will develop irreversible coronary artery lesions (CAL). Pentraxin-3 (PTX-3) has been well-studied in inflammatory diseases, particularly in cardiovascular diseases associated with vascular endothelial dysfunction. We hypothesized that PTX-3 plays an important role in the development of KD-associated CAL and investigated the circulating levels of PTX-3 in the serum of KD patients. Children with acute KD were followed from diagnosis through normalization of the clinical parameters of inflammation (convalescent phase). Serum samples were obtained and echocardiograms were conducted at several phases of the illness: acute [prior to intravenous immunoglobulin (IVIG) treatment], sub-acute (5-10 days after IVIG treatment), and convalescent (1-4 months after KD diagnosis). Seventy children were included in the final cohort of the study, of whom 26 (37%) presented with CAL and 18 (26%) developed IVIG resistance. The patients included in this study came from diverse ethnic backgrounds, mostly with mixed ancestry/ ethnicity. Significantly increased PTX-3 levels were observed during the acute phase of KD compared to the sub-acute and the convalescent phases. The PTX-3 levels during acute KD were significantly higher among KD patients with CAL compared to patients with normal coronary arteries (NCA). Also, the PTX-3 levels were significantly higher in patients with IVIG resistance. Furthermore, the PTX-3 levels were significantly higher in IVIG-resistant KD patients with CAL as compared to the NCA group. Moreover, the PTX-3 levels were significantly correlated to coronary artery z-score during acute KD and to neutrophil counts throughout KD progression regardless of coronary artery z-score. Elevated PTX-3 levels correlated to elevated neutrophil counts, a known source of PTX-3 in acute inflammation and an important player in the development of KD vasculitis. We, therefore, suggest PTX-3 as a novel factor in the development of KD-associated CAL and propose neutrophil-derived PTX-3 as contributing to KD vascular dysfunction.

P2RY12:rs7637803 TT variant genotype increases coronary artery aneurysm risk in Kawasaki disease in a southern Chinese population

BACKGROUND

Activated-platelet increases the risk of thrombosis in Kawasaki disease (KD) patients with a coronary artery aneurysm (CAA). The ADP pathway is one of the platelet activation and aggregation pathways. The P2RY12 gene encodes the ADP receptor that is highly concentrated on platelets. However, few studies have reported on P2RY12 in relation to KD susceptibility with or without CAA.

METHODS

We recruited 1335 healthy controls and 776 KD patients, including 103 with CAA, and selected five P2RY12 polymorphisms: rs9859538, rs1491974, rs7637803, rs6809699 and rs2046934. The present study focused on the relationship between the P2RY12 polymorphisms and KD with or without CAA.

RESULTS

Among all of the selected polymorphisms, single-locus analysis showed no significant association between the P2RY12 polymorphism and KD susceptibility. However, we found a significant relationship between rs7637803 and CAA risk in KD patients [CT versus CC: odds ratio (OR) = 0.41, 95% confidence interval (CI) = 0.22-0.75; p = 0.0041; TT versus CC: OR = 2.90, 95% CI = 1.12-7.46; p = 0.0276]. Stratification analysis by age in KD patients indicated that the rs7637803 TT genotype increased CAA formation risk among children aged (OR = 3.90, 95% CI = 1.42-10.69; p = 0.0081) and increased the onset risk of CAA in males (OR = 6.28, 95% CI = 2.01-19.65; p = 0.0016). The combined effect of the five selected P2RY12 risk genotypes with the KD patients compared to non-mutated P2RY12 genotypes (score: 0) showed that patients with P2RY12 genotype polymorphisms (score: 1-5) had a significantly increased CAA risk (p = 0.0086). Stratification analysis for the severity of CAA found that the rs7637803 TT genotype reduced giant CAA (GCAA) risk (OR = 4.60, 95% CI = 1.70-12.41; p = 0.0026).

CONCLUSIONS

The results of the present study indicate that the P2RY12 rs7637803 genotype might be used as a biomarker to predict the occurrence of GCAA.

Potential role of platelets for atherosclerotic events in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease with increased risk of cardiovascular events and mortality that can be attributed to accelerated atherosclerosis. This pilot study aimed to investigate if changes in blood parameters were compatible with atherosclerotic events in RA patients. To this aim, 45 RA women (aged more than 18 years), and 25 age and gender-matched healthy donors (HD) were included. Biomarkers of oxidative stress, platelet activation and platelet aggregation were analysed in RA patients at baseline and after six months of treatment with disease modifying anti-rheumatic drugs (DMARDs). Flow cytometry analysis revealed that ca. 4% of platelets was in activated state (evaluated in term of Annexin V and PAC-1 positivity) in RA patients at baseline, and that the 76% of platelets displayed mitochondrial hyperpolarization. Moreover, platelets from RA patients at baseline aggregated more than those from HD after whole blood treatment with adenosine diphosphate. Interestingly, platelet aggregation in patients at baseline positively correlated with disease activity measured by DAS28 score. After six months of treatment with DMARDs, platelet activation and platelet aggregation reached values comparable to those of HD. Our preliminary data suggest that platelets might play an active role in the atherosclerosis occurring in RA patients.

Kawasaki disease: guidelines of the Italian Society of Pediatrics, part I - definition, epidemiology, etiopathogenesis, clinical expression and management of the acute phase

The primary purpose of these practical guidelines related to Kawasaki disease (KD) is to contribute to prompt diagnosis and appropriate treatment on the basis of different specialists’ contributions in the field. A set of 40 recommendations is provided, divided in two parts: the first describes the definition of KD, its epidemiology, etiopathogenetic hints, presentation, clinical course and general management, including treatment of the acute phase, through specific 23 recommendations.

Their application is aimed at improving the rate of treatment with intravenous immunoglobulin and the overall potential development of coronary artery abnormalities in KD. Guidelines, however, should not be considered a norm that limits treatment options of pediatricians and practitioners, as treatment modalities other than those recommended may be required as a result of peculiar medical circumstances, patient’s condition, and disease severity or complications.

Relationship between IL-27 and coronary arterial lesions in children with Kawasaki disease

Kawasaki disease (KD) arises due to the disorder of the inflammation response and faulty immune regulation. Interleukin-27 (IL-27) is a novel cytokine with both pro-inflammatory and anti-inflammatory effects. This study investigated the relationship between serum levels of IL-27, Interleukin-17A (IL-17A), Interleukin-10 (IL-10), Interleukin-6 (IL-6), Interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and coronary artery lesions (CALs) in patients with KD. We obtained blood samples from 81 children with KD before intravenous immunoglobulin (IVIG) therapy. Levels of IL-27, IL-17A, IL-10, IL-6, IL-1β and TNF-α were measured in 251 cases, including 4 groups: the normal control group, NC (n = 90), febrile control, FC (n = 80), KD without coronary arteries (n = 41) and KD with coronary arterial lesions (n = 40). White blood cells counts (WBC), red blood cells counts (RBC), hemoglobin, C-reactive protein (CRP), erythrocyte sedimentation rate and procalcitonin (PCT) were tested in all subjects. Levels of IL-27, IL-10, IL-17A, IL-6, IL-1β and TNF-α were significantly elevated, and RBC and hemoglobin significantly decreased in the group of KD group compared with febrile and control groups. IL-27, IL-6, IL-1β and TNF-α serum levels are even higher in KD children with CALs. There was positive relationship between serum levels of IL-27 and WBC, CRP, PCT, IL-10, IL-17A, IL-6 and TNF-α in children with KD. The up-regulation of IL-27 may be closely linked to up-regulation of systemic pro-inflammatory markers in acute KD. Morover, IL-27 may be involved in the development of CALs in acute KD.

Pathogenetic determinants in Kawasaki disease: the haematological point of view

Kawasaki disease is a multisystemic vasculitis that can result in coronary artery lesions. It predominantly affects young children and is characterized by prolonged fever, diffuse mucosal inflammation, indurative oedema of the hands and feet, a polymorphous skin rash and non‐suppurative lymphadenopathy. Coronary artery involvement is the most important complication of Kawasaki disease and may cause significant coronary stenosis resulting in ischemic heart disease. The introduction of intravenous immunoglobulin decreases the incidence of coronary artery lesions to less than 5%. The etiopathogenesis of this disease remains unclear. Several lines of evidence suggest that an interplay between a microbial infection and a genetic predisposition could take place in the development of the disease. In this review, we summarize the state of the art of pathogenetic mechanisms of Kawasaki disease underscoring the relevance of haematological features as a novel field of investigation.

In Vitro Susceptibility of Wistar Rat Platelets to Hydrogen Peroxide and AAPH-Induced Oxidative Stress

Hydroxyl and peroxyl radicals are biologically active species because of their likelihood to damage cellular constituents. An in vitro study on Wistar rats was conducted to investigate the influence of hydrogen peroxide (H2O2) and 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) on platelets and compare the vulnerability of platelets to oxidative stress (OS) induced by these two free radical initiators. Isolated platelets were divided into controls (without free radical initiators; n = 5) and experimentals (with free radical initiators; n = 5). Different concentrations (0.5, 1.0 and 2.0) of free radical initiators H2O2 and AAPH were used to treat the platelets and incubated for 5, 15 and 30 min. Biomarkers such as platelet aggregation, superoxide generation, lipid peroxidation (thiobarbituric acid reactive substances, conjugate dienes), protein oxidation (protein carbonyls, sulfhydryls) and antioxidant enzymes were assessed. In H2O2 and AAPH treated platelets, though OS was observed at concentrations of 0.5 and 1.0 mM, platelets could tolerate the oxidative insult. Treatment of platelets with 2.0 mM H2O2 demonstrated the onset of irreversible changes in platelets as observed in the results of increased superoxide generation and lipid peroxidation products. In 2.0 mM AAPH platelets, the oxidative damage was evident as indicated through increased aggregation, superoxide generation and conjugate dienes and lower protein sulfhydryls. Platelets were more susceptible to AAPH than H2O2, as AAPH acted on both lipids and proteins whereas H2O2 acted only on lipids. This study gives insight on platelet survival under different OS situations.

Biologicals, platelet apoptosis and human diseases: An outlook

Platelets, once considered mediators of hemostasis and thrombosis, are now known to be involved in wound healing, inflammation, cardiovascular diseases, diabetes, arthritis, and cancer. Recent reports attest that platelets possess the cellular machinery to undergo apoptosis and that platelet apoptosis can be triggered by myriad stimuli including chemical and physical agonists, and pathophysiological conditions. Augmented rate of platelet apoptosis leads to thrombocytopenia, bleeding disorders and microparticle generation. Despite knowing the significant role of platelets in health and disease, and that any alterations in platelet functions can wreak havoc to the health, the offshoot reactions of therapeutic drugs on platelets and the far-reaching consequences are often neglected. The present review focuses on the impact of platelet apoptosis and the role of platelet-derived microparticles on different pathophysiological conditions. It also touches upon the effects of biologicals on platelets, and discusses the need to overcome the adverse effects of pro-apoptotic drugs through auxiliary therapy.

Asymmetric and symmetric dimethylarginine are associated with coronary artery lesions in Kawasaki disease

OBJECTIVE

To determine whether 3 biomarkers, L-arginine, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA), can predict outcomes in patients with Kawasaki disease (KD).

STUDY DESIGN

Plasma levels of L-arginine, ADMA, and SDMA were measured in 39 patients with KD and 27 febrile control patients.

RESULTS

Plasma L-arginine, ADMA, and SDMA levels were lower in patients with KD than in control patients before treatment with intravenous immunoglobulin (IVIG; P=.027, P<.001, and P<.001, respectively). After treatment with IVIG, L-arginine, ADMA, L-arginine/ADMA ratios, and arginine methylation ([ADMA+SDMA]/L-arginine) increased significantly (P<.001, P=.001, P=.014, and P=.001, respectively). Compared with control patients, persistent lower SDMA and higher ADMA/SDMA ratios existed in patients with KD. Furthermore, a lesser magnitude of change in terms of L-arginine and ADMA/SDMA ratios after IVIG treatment was associated with the formation of coronary dilation (P=.025, and .029, respectively).

CONCLUSION

Levels of L-arginine, ADMA, and SDMA appear to be associated with KD. Lower L-arginine levels and ADMA/SDMA after treatment with IVIG was associated with coronary artery abnormalities patients with KD.

Redox control of platelet functions in physiology and pathophysiology

SIGNIFICANCE

An imbalance between the production and the detoxification of reactive oxygen species and reactive nitrogen species (ROS/RNS) can be implicated in many pathological processes. Platelets are best known as primary mediators of hemostasis and can be either targets of ROS/RNS or generate radicals during cell activation. These conditions can dramatically affect platelet physiology, leading even, as an ultimate event, to the cell number modification. In this case, pathological conditions such as thrombocytosis (promoted by increased cell number) or thrombocytopenia and myelodysplasia (promoted by cell decrease mediated by accelerated apoptosis) can occur.

RECENT ADVANCES

Usually, in peripheral blood, ROS/RNS production is balanced by the rate of oxidant elimination. Under this condition, platelets are in a nonadherent "resting" state. During endothelial dysfunction or under pathological conditions, ROS/RNS production increases and the platelets respond with specific biochemical and morphologic changes. Mitochondria are at the center of these processes, being able to both generate ROS/RNS, that drive redox-sensitive events, and respond to ROS/RNS-mediated changes of the cellular redox state. Irregular function of platelets and enhanced interaction with leukocytes and endothelial cells can contribute to pathogenesis of atherosclerotic and thrombotic events.

CRITICAL ISSUES

The relationship between oxidative stress, platelet death, and the activation-dependent pathways that drive platelet pro-coagulant activity is unclear and deserves to be explored.

FUTURE DIRECTIONS

Expanding knowledge about how platelets can mediate hemostasis and modulate inflammation may lead to novel and effective therapeutic strategies for the long and growing list of pathological conditions that involve both thrombosis and inflammation.

Therapeutic drug-induced platelet apoptosis: an overlooked issue in pharmacotoxicology

The surfacing of the applied fields of biology such as, biotechnology, pharmacology and drug discovery was a boon to the modern man. However, it had its share of disadvantages too. The indiscriminate use of antibiotics and other biological drugs resulted in numerous adverse reactions including thrombocytopenia. One of the reasons for drug-induced thrombocytopenia could be attributed to an enhanced rate of platelet apoptosis, which is a less investigated aspect. The present essay sheds light on the adverse (pro-apoptotic) effects of some of the commonly used drugs and antibiotics on platelets viz. cisplatin, aspirin, vancomycin and balhimycin. Furthermore, the undesirable reactions resulting from chemotherapy could be attributed at least to some extent to the systemic stress induced by microparticles, which in turn are the byproducts of platelet apoptosis. Thereby, the essay aims to highlight the challenges in the emerging trend of cross-disciplinary implications, i.e., drug-induced platelet apoptosis, which is a nascent field. Thus, the different mechanisms through which drugs induce platelet apoptosis are discussed, which also opens up a new perspective through which the adverse effects of commonly used drugs could be dealt. The drug-associated platelet toxicity is of grave concern and demands immediate attention. Besides, it would also be appealing to examine the platelet pro-apoptotic effects of other commonly used therapeutic drugs.

Does oxidative stress play a critical role in cardiovascular complications of Kawasaki disease?

The aim of the present work was to evaluate the contribution of the different reactive oxidizing species to systemic oxidative stress in the whole blood of patients with Kawasaki disease (KD). This is a rare generalized systemic vasculitis typical of the early childhood characterized by inflammation and endothelial dysfunction with a high risk for cardiovascular fatal events. We found that, compared to age-matched healthy donors, blood from KD patients showed increased production of oxygen- and nitrogen-derived species as detected by electron paramagnetic resonance (EPR) spin probing with the cyclic hydroxylamine 1-hydroxy-3-carboxy-pyrrolidine. The (•)NO pathway involvement was also confirmed by the decreased concentrations of the endogenous (•)NO synthase inhibitor asymmetric dimethyl-arginine and the increased amounts of 3-nitrotyrosine in plasma. Further, increased plasma yields of the proinflammatory enzyme myeloperoxidase were also observed. The appearance of circulating red blood cell alterations typically associated with oxidative imbalance and premature aging (e.g., decrease of total thiol content, glycophorin A, and CD47 expression, as well as increase of phosphatidylserine externalization) has also been detected. Collectively, our observations lead to hypothesize that the simultaneous oxidative and nitrative stress occurrence in the blood of KD patients may play a pathogenetic role in the cardiovascular complications often associated with this rare disease.

Comparison of the laboratory data between Kawasaki disease and enterovirus after intravenous immunoglobulin treatment

Kawasaki disease (KD) is a systemic vasculitis of unknown etiology. The laboratory findings before and after intravenous immunoglobulin (IVIG) in KD have been discussed, but the characteristics of IVIG therapy still are unclear. This study aimed to compare laboratory data from patients with KD and enterovirus (EV) infection to evaluate the differences after IVIG therapy. The study enrolled 171 KD patients and 38 EV patients treated with a single dose of IVIG from 2003 to 2010. Laboratory data including total white blood cell counts (WBC) and hemoglobin (Hb), platelet, segment, lymphocyte, eosinophil, and monocyte levels were analyzed. Compared with the KD patients, the EV patients had higher Hb, lymphocyte, and monocyte levels and lower eosinophil levels before IVIG treatment (p < 0.05). After IVIG treatment, the KD patients had lower Hb and segment levels but higher platelet, lymphocyte, and eosinophil levels than the EV patients (p < 0.05). In the KD patients, the platelet, eosinophil, and monocyte levels increased after IVIG treatment, whereas Hb, WBC, and segment levels decreased significantly (p < 0.001). In the EV patients, eosinophil levels increased after IVIG treatment, whereas WBC and Hb levels decreased significantly (p < 0.05). The study results provide evidence that eosinophilia may be related to IVIG therapy in KD and EV patients. The KD patients had higher eosinophil levels both before and after IVIG therapy than the EV patients, which may have been due to the inflammatory mechanism of KD. The KD patients had higher platelet levels than the EV patients, suggesting that platelets are involved in the inflammatory response to KD.

Elevated plasma advanced oxidation protein products in children with Henoch-Schonlein purpura

Henoch-Schonlein purpura (HSP) is a systemic vasculitis characterized by involvement of skin, joints, gastrointestinal tract (GIT), and kidney; its pathogenesis is still controversial. The aim of our study was to investigate the role of oxidative stress in the pathogenesis of HSP. Plasma advanced oxidation protein products (AOPP) level was measured in 29 children with HSP at the onset of the disease and during remission in comparison with 30 healthy subjects. Patients at the active stage had significantly higher AOPP levels than those at the remission stage of HSP and the controls (42.9 ± 25.7, 30.6 ± 11.8, 27.9 ± 11.2 mmol/l; P = 0.027 and P = 0.023 respectively). The mean AOPP levels of the patients with arthritis and/or arthralgia were significantly higher those than without joint involvement (48.3 ± 26.0 and 22.3 ± 9.3, P = 0.036 respectively). However, AOPP levels were similar in patients with and without gastrointestinal involvement. Plasma AOPP levels were positively correlated with leukocyte and thrombocyte count at disease onset, whereas they were found to be negatively correlated with serum glucose and sodium levels. The mean thrombocyte count was the only independent predictor of increased level of AOPP in regression analysis (β = 0.407; P = 0.029). In conclusion, this study showed that increased oxidative stress may play an important role in the pathogenesis of HSP. Also, we suggest that higher platelet count might be an indirect indicator of oxidative stress in these patients. Further research is required to identify the potential association between oxidative stress and increased thrombocyte count in children with HSP.