Increased soluble and platelet-associated CD40 ligand in essential thrombocythemia and reactive thrombocytosis

Crosstalk between Platelets and SARS-CoV-2: Implications in Thrombo-Inflammatory Complications in COVID-19

The SARS-CoV-2 virus, causing the devastating COVID-19 pandemic, has been reported to affect platelets and cause increased thrombotic events, hinting at the possible bidirectional interactions between platelets and the virus. In this review, we discuss the potential mechanisms underlying the increased thrombotic events as well as altered platelet count and activity in COVID-19. Inspired by existing knowledge on platelet-pathogen interactions, we propose several potential antiviral strategies that platelets might undertake to combat SARS-CoV-2, including their abilities to internalize the virus, release bioactive molecules to interfere with viral infection, and modulate the functions of immune cells. Moreover, we discuss current and potential platelet-targeted therapeutic strategies in controlling COVID-19, including antiplatelet drugs, anticoagulants, and inflammation-targeting treatments. These strategies have shown promise in clinical settings to alleviate the severity of thrombo-inflammatory complications and reduce the mortality rate among COVID-19 patients. In conclusion, an in-depth understanding of platelet-SARS-CoV-2 interactions may uncover novel mechanisms underlying severe COVID-19 complications and could provide new therapeutic avenues for managing this disease.

The role of platelets in immune-mediated inflammatory diseases

Immune-mediated inflammatory diseases (IMIDs) are characterized by excessive and uncontrolled inflammation and thrombosis, both of which are responsible for organ damage, morbidity and death. Platelets have long been known for their role in primary haemostasis, but they are now also considered to be components of the immune system and to have a central role in the pathogenesis of IMIDs. In patients with IMIDs, platelets are activated by disease-specific factors, and their activation often reflects disease activity. Here we summarize the evidence showing that activated platelets have an active role in the pathogenesis and the progression of IMIDs. Activated platelets produce soluble factors and directly interact with immune cells, thereby promoting an inflammatory phenotype. Furthermore, platelets participate in tissue injury and promote abnormal tissue healing, leading to fibrosis. Targeting platelet activation and targeting the interaction of platelets with the immune system are novel and promising therapeutic strategies in IMIDs.

Mechanisms of platelet activation in cancer-associated thrombosis: a focus on myeloproliferative neoplasms

Platelets are anucleate blood cells that play key roles in thrombosis and hemostasis. Platelets are also effector cells in malignancy and are known to home into the microenvironment of cancers. As such, these cells provide central links between the hemostatic system, inflammation and cancer progression. Activation of platelets by cancers has been postulated to contribute to metastasis and progression of local tumor invasion. Similarly, cancer-activated platelets can increase the risk of development of both arterial and venous thrombosis; a major contributor to cancer-associated morbidity. Platelet granules secretion within the tumor environment or the plasma provide a rich source of potential biomarkers for prediction of thrombotic risk or tumor progression. In the case of myeloproliferative neoplasms (MPNs), which are characterized by clonal expansion of myeloid precursors and abnormal function and number of erythrocytes, leukocytes and platelets, patients suffer from thrombotic and hemorrhagic complications. The mechanisms driving this are likely multifactorial but remain poorly understood. Several mouse models developed to recapitulate MPN phenotype with one of the driving mutations, in JAK2 (JAK2V617F) or in calreticulin (CALR) or myeloproliferative leukemia virus oncogene receptor (MPL), have been studied for their thrombotic phenotype. Variability and discrepancies were identified within different disease models of MPN, emphasizing the complexity of increased risk of clotting and bleeding in these pathologies. Here, we review recent literature on the role of platelets in cancer-associated arterial and venous thrombosis and use MPN as case study to illustrate recent advances in experimental models of thrombosis in a malignant phenotype. We address major mechanisms of tumor-platelet communication leading to thrombosis and focus on the role of altered platelets in promoting thrombosis in MPN experimental models and patients with MPN. Recent identification of platelet-derived biomarkers of MPN-associated thrombosis is also reviewed, with potential therapeutic implications.

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.

Higher platelet count, even within normal range, is associated with increased arterial stiffness in young and middle-aged adults

Background: Platelet counts and mean platelet volume (MPV) are related to cardiovascular disease, but a thorough investigation into the connection between increased arterial stiffness, MPV, and platelet counts is lacking. This study aimed to explore the association of platelet count and MPV with arterial stiffness in young and middle-aged adults.

Methods: A total of 2464 participants who underwent health checkups at National Cheng Kung University Hospital, Taiwan from November 2018 to December 2019 were included. We excluded participants aged <18 or >50 years; who are pregnant; on medication for dyslipidemia; with abnormal platelet count, incomplete data, and past history of hematologic disorders. We examined the association of platelet counts and MPV values with brachial-ankle pulse wave velocity (baPWV) levels and increased arterial stiffness.

Results: Platelet count was significantly higher in participants with increased arterial stiffness than in those without. The multiple linear regression model revealed that platelet counts were positively associated with baPWV levels (β = 1.88, 95% confidence interval (CI): 0.96 to 2.80). In the binary logistic regression analysis, subjects in the higher platelet counts quartiles had a higher risk of developing increased arterial stiffness (Q2 vs. Q1: odds ratio (OR): 1.54, 95% CI: 1.05 to 2.27; Q3 vs. Q1: OR: 1.57, 95% CI: 1.06 to 2.33; and Q4 vs. Q1: OR: 2.23, 95% CI: 1.50 to 3.30). In contrast, MPV levels were not associated with arterial stiffness.

Conclusions: Platelet count in midlife was positively associated with baPWV levels. Participants in higher platelet quartiles were at risk for increased arterial stiffness.

High plasma CD40 ligand level is associated with more advanced stages and worse prognosis in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is often associated with elevated platelet count (> 400 × 10⁹/L), known as thrombocytosis. The role of CD40 ligand (CD40L), a member of the tumor necrosis factor family, is controversial in CRC. Circulating CD40L is higher in CRC, but its relationship with disease staging and local and distant metastasis is not clear. Although most of the circulating CD40L is produced by platelets, no previous study investigated its relationship with CRC-related thrombocytosis.

AIM

To investigate the role of CD40L to predict the outcome of CRC and its relation to thrombocytosis.

METHODS

A total of 106 CRC patients and 50 age and sex-matched control subjects were enrolled for the study. Anamnestic data including comorbidities and histopathological data were collected. Laboratory measurements were performed at the time of CRC diagnosis and 1.5 mo and at least 6 mo after the surgical removal of the tumor. Plasma CD40L and thrombopoietin were measured via enzyme-linked immunosorbent assay, while plasma interleukin-6 was measured via electrochemiluminescence immunoassay. Patient follow-ups were terminated on January 31, 2021.

RESULTS

Plasma CD40L of CRC patients was tendentiously higher, while platelet count (P = 0.0479), interleukin-6 (P = 0.0002), and thrombopoietin (P = 0.0024) levels were significantly higher as opposed to the control subjects. Twelve of the 106 CRC patients (11.3%) had thrombocytosis. Significantly higher CD40L was found in the presence of distant metastases (P = 0.0055) and/or thrombocytosis (P = 0.0294). A connection was found between CD40L and platelet count (P = 0.0045), interleukin-6 (P = 0.0130), and thrombocytosis (P = 0.0155). CD40L was constant with the course of CRC, and all baseline differences persisted throughout the whole study. Both pre- and postoperative elevated platelet count, CD40L, and interleukin-6 level were associated with poor overall and disease-specific survival of patients. The negative effect of CD40L and interleukin-6 on patient survival remained even after the stratification by thrombocytosis.

CONCLUSION

CD40L levels of CRC patients do not change with the course of the disease. The CD40L level is strongly correlated with platelet count, interleukin-6, thrombocytosis, and the presence of distant metastases.

Diagnostic and Prognostic Blood Biomarkers in Transient Ischemic Attack and Minor Ischemic Stroke: An Up-To-Date Narrative Review

INTRODUCTION

Early diagnosis and correct risk stratification in patients with transient ischemic attack (TIA) and minor ischemic stroke (MIS) is crucial for the high rate of subsequent disabling stroke. Although highly improved, diagnosis and prognostication of TIA/MIS patients remain still based on clinical and neuroimaging findings, with some inter-rater variability even among trained neurologists.

OBJECTIVES

To provide an up-to-date overview of diagnostic and prognostic blood biomarkers in TIA and MIS patients.

MATERIAL AND METHODS

We performed a bibliographic search on PubMed database with last access on July 10^th 2021. More than 680 articles were screened and we finally included only primary studies on blood biomarkers.

RESULTS

In a narrative fashion, we discussed about blood biomarkers investigated in TIA/MIS patients, including inflammatory, thrombosis, neuronal injury and cardiac analytes, antibodies and microRNAs. Other soluble molecules have been demonstrated to predict the risk of recurrent cerebrovascular events or treatment response in these patients. A rapid point of care assay, combining the determination of different biomarkers, has been developed to improve triage recognition of acute cerebrovascular accidents.

CONCLUSIONS

The implementation of blood biomarkers in the clinical management of TIA/MIS could ameliorate urgent identification, risk stratification and individual treatment choice. Large prospective and longitudinal studies, adopting standardized sampling and analytic procedures, are needed to clarify blood biomarkers kinetic and their relationship with TIA and minor stroke etiology.

Trypanosoma cruzi Induces B Cells That Regulate the CD4+ T Cell Response

Trypanosoma cruzi infection induces a polyclonal B cell proliferative response characterized by maturation to plasma cells, excessive generation of germinal centers, and secretion of parasite-unrelated antibodies. Although traditionally reduced to the humoral response, several infectious and non-infectious models revealed that B lymphocytes could regulate and play crucial roles in cellular responses. Here, we analyze the trypomastigote-induced effect on B cells, their effects on CD4+ T cells, and their correlation with in vivo findings. The trypomastigotes were able to induce the proliferation and the production of IL-10 or IL-6 of naïve B cells in co-culture experiments. Also, we found that IL-10-producing B220lo cells were elicited in vivo. We also found up-regulated expression of FasL and PD-L1, proteins involved in apoptosis induction and inhibition of TCR signaling, and of BAFF and APRIL mRNAs, two B-cell growth factors. Interestingly, it was observed that IL-21, which plays a critical role in regulatory B cell differentiation, was significantly increased in B220+/IL-21+ in in vivo infections. This is striking since the secretion of IL-21 is associated with T helper follicular cells. Furthermore, trypomastigote-stimulated B-cell conditioned medium dramatically reduced the proliferation and increased the apoptotic rate on CD3/CD28 activated CD4+ T cells, suggesting the development of effective regulatory B cells. In this condition, CD4+ T cells showed a marked decrease in proliferation and viability with marginal IL-2 or IFNγ secretion, which is counterproductive with an efficient immune response against T. cruzi. Altogether, our results show that B lymphocytes stimulated with trypomastigotes adopt a particular phenotype that exerts a strong regulation of this T cell compartment by inducing apoptosis, arresting cell division, and affecting the developing of a proinflammatory response.

Management Issues and Controversies in Low-Risk Patients with Essential Thrombocythemia and Polycythemia Vera

PURPOSE OF REVIEW

Essential thrombocythemia (ET) and polycythemia vera (PV) are the most common myeloproliferative neoplasms (MPNs). Treatment of ET and PV is based on the risk for subsequent thrombosis. High-risk patients, defined as older than 60, JAK2 V617F-positive patients, or patients with a history of prior thrombosis, merit cytoreduction to control blood counts, whereas a watchful waiting paradigm is utilized in low-risk patients. However, low-risk patients have a host of other specific management issues that arise during their disease course. This review will discuss the most common management issues specific to the care of low-risk patients, including anti-platelet therapy dosing, pregnancy, and indications for early cytoreduction.

RECENT FINDINGS

Although low-dose aspirin is well established in PV, its indications and dosing regimens are less clear in ET. Recent evidence has supported twice daily low-dose aspirin in ET and observation alone in very low-risk ET patients. Pregnancy is not contraindicated in MPNs, and we recommend aspirin throughout pregnancy with consideration for prophylactic postpartum anticoagulation. High phlebotomy needs, symptom burden, and extreme thrombocytosis are common reasons for initiation of cytoreduction in low-risk patients, although we typically do not start cytoreduction for an isolated high platelet count alone. Recent data has also demonstrated a potential disease-modifying effect of interferons in MPNs, with some experts now advocating the early use of interferon in low-risk patients, although more mature data is needed before practice guidelines change. We evaluate the literature to inform clinical decision-making regarding these controversies, including most recent data that has challenged the "watchful waiting" paradigm. Our discussion provides guidance on common clinical scenarios seen in low-risk ET and PV patients, who face a myriad of complex management decisions in their care.

Revisiting Platelets and Toll-Like Receptors (TLRs): At the Interface of Vascular Immunity and Thrombosis

While platelet function has traditionally been described in the context of maintaining vascular integrity, recent evidence suggests that platelets can modulate inflammation in a much more sophisticated and nuanced manner than previously thought. Some aspects of this expanded repertoire of platelet function are mediated via expression of Toll-like receptors (TLRs). TLRs are a family of pattern recognition receptors that recognize pathogen-associated and damage-associated molecular patterns. Activation of these receptors is crucial for orchestrating and sustaining the inflammatory response to both types of danger signals. The TLR family consists of 10 known receptors, and there is at least some evidence that each of these are expressed on or within human platelets. This review presents the literature on TLR-mediated platelet activation for each of these receptors, and the existing understanding of platelet-TLR immune modulation. This review also highlights unresolved methodological issues that potentially contribute to some of the discrepancies within the literature, and we also suggest several recommendations to overcome these issues. Current understanding of TLR-mediated platelet responses in influenza, sepsis, transfusion-related injury and cardiovascular disease are discussed, and key outstanding research questions are highlighted. In summary, we provide a resource—a “researcher’s toolkit”—for undertaking further research in the field of platelet-TLR biology.

A randomized double-blind trial of 3 aspirin regimens to optimize antiplatelet therapy in essential thrombocythemia

Essential thrombocythemia (ET) is characterized by abnormal megakaryopoiesis and enhanced thrombotic risk. Once-daily low-dose aspirin is the recommended antithrombotic regimen, but accelerated platelet generation may reduce the duration of platelet cyclooxygenase-1 (COX-1) inhibition. We performed a multicenter double-blind trial to investigate the efficacy of 3 aspirin regimens in optimizing platelet COX-1 inhibition while preserving COX-2-dependent vascular thromboresistance. Patients on chronic once-daily low-dose aspirin (n = 245) were randomized (1:1:1) to receive 100 mg of aspirin 1, 2, or 3 times daily for 2 weeks. Serum thromboxane B2 (sTXB2), a validated biomarker of platelet COX-1 activity, and urinary prostacyclin metabolite (PGIM) excretion were measured at randomization and after 2 weeks, as primary surrogate end points of efficacy and safety, respectively. Urinary TX metabolite (TXM) excretion, gastrointestinal tolerance, and ET-related symptoms were also investigated. Evaluable patients assigned to the twice-daily and thrice-daily regimens showed substantially reduced interindividual variability and lower median (interquartile range) values for sTXB2 (ng/mL) compared with the once-daily arm: 4 (2.1-6.7; n = 79), 2.5 (1.4-5.65, n = 79), and 19.3 (9.7-40; n = 85), respectively. Urinary PGIM was comparable in the 3 arms. Urinary TXM was reduced by 35% in both experimental arms. Patients in the thrice-daily arm reported a higher abdominal discomfort score. In conclusion, the currently recommended aspirin regimen of 75 to 100 once daily for cardiovascular prophylaxis appears to be largely inadequate in reducing platelet activation in the vast majority of patients with ET. The antiplatelet response to low-dose aspirin can be markedly improved by shortening the dosing interval to 12 hours, with no improvement with further reductions (EudraCT 2016-002885-30).

Essential thrombocythemia: a hemostatic view of thrombogenic risk factors and prognosis

Essential thrombocythemia (ET) is a classical myeloproliferative neoplasm that is susceptible to hypercoagulable state due to impaired hemostatic system, so that thrombotic complications are the leading cause of mortality in ET patients. The content used in this article has been obtained by the PubMed database and Google Scholar search engine from English-language articles (2000-2019) using the following keywords: "Essential thrombocythemia," "Thrombosis," "Risk factors" and "Hemostasis. In this neoplasm, the count and activity of cells such as platelets, leukocytes, endothelial cells, as well as erythrocytes are increased, which can increase the risk of thrombosis through rising intercellular interactions, expression of surface markers, and stimulation of platelet aggregation. In addition to these factors, genetic polymorphisms in hematopoietic stem cells (HSCs), including mutations in JAK2, CALR, MPL, or genetic abnormalities in other genes associated with the hemostatic system may be associated with increased risk of thrombotic events. Moreover, disruption of coagulant factors can pave the way for thrombogeneration. Therefore, the identification of markers related to cell activation, genetic abnormalities, or alternation in the coagulant system can be used together as diagnostic and prognostic markers for the occurrence of thrombosis among ET patients. Thus, because thrombotic complications are the main factors of mortality in ET patients, a hemostatic viewpoint and risk assessment of cellular, genetic, and coagulation factors can have prognostic value and contribute to the choice of effective treatment and prevention of thrombosis.

Combined prognostic significance of D-dimer level and platelet count in acute ischemic stroke

BACKGROUND

D-dimer level and platelet count (PC) have been reported separately as significant independent predictors of Acute Ischemic Stroke (AIS). Here, we aimed to investigate the combined prognostic value of abnormal D-dimer level and PC as defined for specific in-hospital and long-term outcomes in AIS patients.

METHODS

A total of 1468 patients admitted for ischemic stroke within 24 h of symptom onset from April 1, 2016 to November 31, 2019 at the Department of Neurology, the First Affiliated Hospital of Harbin Medical University were included in the final analysis. Eligible subjects were divided into four groups in terms of their levels of D-dimer and PC: DD-PC- (normal D-dimer level and normal PC), DD-PC+ (normal D-dimer level and abnormal PC), DD+PC- (higher D-dimer level and normal PC), and DD+PC+ (higher D-dimer level and abnormal PC). Logistic regression model and multinomial logit model were used to estimate the combined effect of D-dimer level and PC on in-hospital outcomes including discharge outcome and early neurological changes, and poor outcomes at 3, 6 and 12 months.

RESULTS

DD+PC+ was found to be associated with the risk of in-hospital mortality (adjusted odds ratio [OR], 6.904; 95% confidence interval [CI], 2.781-17.144) and 3-month mortality (adjusted OR, 5.455; 95% CI, 2.019-14.743) compared with DD-PC-. Combination of the two indicators significantly improved the independent predictive value for functional outcomes, including early neurological deterioration (END) (OR, 3.622; 95% CI, 1.732-7.573) with threshold of at least 4-point increase on NIHSS, discharge outcome (OR, 2.713; 95% CI, 1.421-5.177); mRS of 0-1 point (OR, 0.409; 95% CI, 0.211-0.792), mRS of 0-2 points (OR, 0.234; 95% CI, 0.118, 0.461), and higher mRS-shift (OR, 2.379; 95% CI, 1.237-4.576) at 3 months; unfavorable outcome at 3 months (OR, 4.280; 95% CI, 2.169-8.446), 6 months (OR, 3.297; 95% CI, 1.452-7.488) and 12 months (OR, 4.157; 95% CI, 1.598-10.816). While comparatively weaker statistical significance was shown in DD+PC- and no correlation was found between adverse outcomes and DD-PC+. Similarly, patients with abnormal D-dimer level and PC were less likely to reach the status of stable or improving.

CONCLUSIONS

Combination of D-dimer level and PC may have more significant prognostic value on END, in-hospital mortality, discharge outcome, and long-term outcomes than either index of D-dimer level or PC alone in AIS patients.

In systemic lupus erythematosus anti-dsDNA antibodies can promote thrombosis through direct platelet activation

Systemic lupus erythematosus (SLE) is associated with a high risk of venous and arterial thrombosis, not necessarily associated with prothrombotic antiphospholipid antibodies (Abs). Alternatively, thrombosis may be due to an increased titer of anti-dsDNA Abs that presumably promote thrombosis via direct platelet activation. Here, we investigated effects of purified anti-dsDNA Abs from the blood of SLE patients, alone or in a complex with dsDNA, on isolated normal human platelets. We showed that anti-dsDNA Abs and anti-dsDNA Ab/dsDNA complexes induced strong platelet activation assessed by enhanced P-selectin expression and dramatic morphological and ultrastructural changes. Electron microscopy revealed a significantly higher percentage of platelets that lost their discoid shape, formed multiple filopodia and had a shrunken body when treated with anti-dsDNA Abs or anti-dsDNA Ab/dsDNA complexes compared with control samples. In addition, these platelets activated with anti-dsDNA Ab/dsDNA complexes typically contained a reduced number of secretory α-granules that grouped in the middle and often merged into a solid electron dense area. Many activated platelets released plasma membrane-derived microvesicles and/or fell apart into subcellular cytoplasmic fragments. Confocal microscopy revealed that platelets treated with anti-dsDNA Ab/dsDNA complex had a heterogeneous distribution of septin2 compared with the homogeneous distribution in control platelets. Structural perturbations were concomitant with mitochondrial depolarization and a decreased content of platelet ATP, indicating energetic exhaustion. Most of the biochemical and morphological changes in platelets induced by anti-dsDNA Abs and anti-dsDNA Ab/dsDNA complexes were prevented by pre-treatment with a monoclonal mAb against FcγRIIA. The aggregate of data indicates that anti-dsDNA Abs alone or in a complex with dsDNA strongly affect platelets via the FcγRIIA receptor. The immune activation of platelets with antinuclear Abs may comprise a prothrombotic mechanism underlying a high risk of thrombotic complications in patients with SLE.

Unexpected low expression of platelet fibrinogen receptor in patients with chronic myeloproliferative neoplasms: how does it change with aspirin?

This study was conducted to evaluate the expression of fibrinogen receptors on platelets of Philadelphia‐negative chronic myeloproliferative neoplasm (MPN) patients. We collected blood samples from 40 consecutive MPN patients and healthy volunteers. We performed flow cytometry analysis of P‐selectin expression and integrin beta‐3, activation of glycoprotein (GP) IIb/IIIa and fibrinogen receptor exposure (PAC‐1 binding). Surprisingly, we found a very low PAC‐1 binding capacity in MPN patients; however, the expression of PAC‐1 was almost completely recovered with aspirin intake. We hypothesize that the hypercoagulable states observed in MPN patients could depend on a primarily plasma‐driven impairment of fibrin turnover and thrombin generation.

Role of NF-κB in Platelet Function

Platelets are megakaryocyte-derived fragments lacking nuclei and prepped to maintain primary hemostasis by initiating blood clots on injured vascular endothelia. Pathologically, platelets undergo the same physiological processes of activation, secretion, and aggregation yet with such pronouncedness that they orchestrate and make headway the progression of atherothrombotic diseases not only through clot formation but also via forcing a pro-inflammatory state. Indeed, nuclear factor-κB (NF-κB) is largely implicated in atherosclerosis and its pathological complication in atherothrombotic diseases due to its transcriptional role in maintaining pro-survival and pro-inflammatory states in vascular and blood cells. On the other hand, we know little on the functions of platelet NF-κB, which seems to function in other non-genomic ways to modulate atherothrombosis. Therein, this review will resemble a rich portfolio for NF-κB in platelets, specifically showing its implications at the levels of platelet survival and function. We will also share the knowledge thus far on the effects of active ingredients on NF-κB in general, as an extrapolative method to highlight the potential therapeutic targeting of NF-κB in coronary diseases. Finally, we will unzip a new horizon on a possible extra-platelet role of platelet NF-κB, which will better expand our knowledge on the etiology and pathophysiology of atherothrombosis.

Acute splenic infarction presenting as an unusual manifestation of essential thrombocythaemia with normal platelet count

Essential thrombocythaemia (ET) is characterised by elevated platelet count by a clonal stem cell disorder of megakaryocytes. Although thrombosis is a common complication of ET, splenic infarction (SI) is extremely rare. Here, we present the case of a 31-year-old Japanese man who presented with sudden-onset severe pain at the left hypochondrium on the day before admission. Enhanced abdominal CT revealed SI. The laboratory test results revealed a normal platelet count (439×10⁹/L). Subsequently, the patient was diagnosed with ET because the platelet count gradually increased to 50.0×10⁴/μL, and JAK2 V617F mutation was identified. Accordingly, low-dose aspirin was initiated, and no thrombotic episode occurred. Nevertheless, 6 months postdischarge, the platelet count gradually increased to >650 × 10⁹/L, and anagrelide was initiated. This case demonstrates an unusual complication of acute SI due to ET under the rare situation of the normal platelet count.

Platelet Count Predicts Adverse Clinical Outcomes After Ischemic Stroke or TIA: Subgroup Analysis of CNSR II

Background: The clinical significance of platelet count (PC) for ischemic cerebrovascular disease is not well-established and further risk stratification according to baseline PC within normal range has not been reported before. We aim to evaluate the prognostic effect of baseline circulating PC within normal range on the risk of long-term recurrent stroke, mortality and functional outcomes after ischemic stroke or TIA.

Methods: We derived data from eligible patients with ischemic stroke or TIA from the China National Stroke Registry (CNSR) II. Participants were divided into quintiles according to baseline PC within normal range (100–450 × 10⁹/L). Multivariable cox regression and logistic regression were adopted to explore the correlation of baseline PC with recurrent stroke, mortality and poor functional outcomes (modified Rankin Scale 3~6) within 1-year follow-up.

Results: Among the16842 eligible participants, the average age was 64.7 ± 11.9, 1,241 (7.4%) had recurrent stroke, 1,377 (8.2%) died, and 3,557 (21.1%) ended up with poor functional outcomes after 1-year follow-up. Compared with the third PC quintile (186–212 × 10⁹/L), patients in the top quintile (249–450 × 10⁹/L) presented with increased risk of recurrent stroke (adjusted hazard ratio 1.21, [1.02–1.45]), all-cause mortality (adjusted hazard ratio 1.43, [1.19–1.73]), and poor functional outcome (adjusted odds ratio 1.49, [1.28–1.74]), while patients in the lowest PC quintile(100–155 × 10⁹/L) had higher risk of poor functional outcome (adjusted odds ratio 1.19, [1.02–1.38]).

Conclusion: In ischemic stroke or TIA patients with platelet count within normal range, platelet count may be a qualified predictor for long-term recurrent stroke, mortality, and poor functional outcome.

Persistent janus kinase-signaling in chronic lymphocytic leukemia patients on ibrutinib: Results of a phase I trial

Methods to deepen clinical responses to ibrutinib are needed to improve outcomes for patients with chronic lymphocytic leukemia (CLL). This study aimed to determine the safety and efficacy of combining a janus kinase (JAK)‐inhibitor with ibrutinib because JAK‐mediated cytokine‐signals support CLL cells and may not be inhibited by ibrutinib. The JAK1/2 inhibitor ruxolitinib was prescribed to 12 CLL patients with abnormal serum beta‐2 microglobulin levels after 6 months or persistent lymphadenopathy or splenomegaly after 12 months on ibrutinib using a 3 + 3 phase 1 trial design (NCT02912754). Ibrutinib was continued at 420 mg daily and ruxolitinib was added at 5, 10, 15, or 20 mg BID for 3 weeks out of five for seven cycles. The break was mandated to avoid anemia and thrombocytopenia observed with ruxolitinib as a single agent in CLL. The combination was well‐tolerated without dose‐limiting toxicities. Cyclic changes in platelets, lymphocytes, and associated chemokines and thrombopoietic factors were observed and partial response criteria were met in 2 of 12 patients. The results suggest that JAK‐signaling helps CLL cells persist in the presence of ibrutinib and ruxolitinib with ibrutinib is well‐tolerated and may be a useful regiment to use in combination therapies for CLL.

The Aspirin Regimens in Essential Thrombocythemia (ARES) phase II randomized trial design: Implementation of the serum thromboxane B2 assay as an evaluation tool of different aspirin dosing regimens in the clinical setting

Once-daily (od), low-dose aspirin (75–100 mg) is recommended to reduce the thrombotic risk of patients with essential thrombocytemia (ET). This practice is based on data extrapolated from other high-risk patients and an aspirin trial in polycythemia vera, with the assumption of similar aspirin pharmacodynamics in the two settings. However, the pharmacodynamics of low-dose aspirin is impaired in ET, reflecting accelerated renewal of platelet cyclooxygenase (COX)-1. ARES is a parallel-arm, placebo-controlled, randomized, dose-finding, phase II trial enrolling 300 ET patients to address two main questions. First, whether twice or three times 100 mg aspirin daily dosing is superior to the standard od regimen in inhibiting platelet thromboxane (TX)A₂ production, without inhibiting vascular prostacyclin biosynthesis. Second, whether long-term persistence of superior biochemical efficacy can be safely maintained with multiple vs. single dosing aspirin regimen. Considering that the primary study end point is serum TXB₂, a surrogate biomarker of clinical efficacy, a preliminary exercise of reproducibility and validation of this biomarker across all the 11 participating centers was implemented. The results of this preliminary phase demonstrate the importance of controlling reproducibility of biomarkers in multicenter trials and the feasibility of using serum TXB₂ as a reliable end point for dose-finding studies of novel aspirin regimens.

Systemic lupus erythematosus and systemic sclerosis: All roads lead to platelets

Systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) are two phenotypically distincts inflammatory systemic diseases. However, SLE and SSc share pathogenic features such as interferon signature, loss of tolerance against self-nuclear antigens and increased tissue damage such as fibrosis. Recently, platelets have emerged as a major actor in immunity including auto-immune diseases. Both SLE and SSc are characterized by strong platelet system activation, which is likely to be both the witness and culprit in their pathogenesis. Platelet activation pathways are multiple and sometimes redundant. They include immune complexes, Toll-like receptors activation, antiphospholipid antibodies and ischemia-reperfusion associated with Raynaud phenomenon. Once activated, platelet promote immune dysregulation by priming interferon production by immune cells, providing CD40L supporting B lymphocyte functions and providing a source of autoantigens. Platelets are actively implicated in SLE and SSc end-organ damage such as cardiovascular and renal disease and in the promotion of tissue fibrosis. Finally, after understanding the main pathogenic implications of platelet activation in both diseases, we discuss potential therapeutics targeting platelets.

Association of thrombocytosis with COPD morbidity: the SPIROMICS and COPDGene cohorts

BACKGROUND

Thrombocytosis has been associated with COPD prevalence and increased all-cause mortality in patients with acute exacerbation of COPD (AECOPD); but whether it is associated with morbidity in stable COPD is unknown. This study aims to determine the association of thrombocytosis with COPD morbidity including reported AECOPD, respiratory symptoms and exercise capacity.

METHODS

Participants with COPD were included from two multi-center observational studies (SPIROMICS and COPDGene). Cross-sectional associations of thrombocytosis (platelet count ≥350 × 10⁹/L) with AECOPD during prior year (none vs. any), exertional dyspnea (modified Medical Research Council (mMRC) score ≥ 2), COPD Assessment Test (CAT) score ≥ 10, six-minute-walk distance (6MWD), and St. George Respiratory questionnaire (SGRQ) were modeled using multivariable logistic or linear regression. A pooled effect estimate for thrombocytosis was produced using meta-analysis of data from both studies.

RESULTS

Thrombocytosis was present in 124/1820 (6.8%) SPIROMICS participants and 111/2185 (5.1%) COPDGene participants. In meta-analysis thrombocytosis was associated with any AECOPD (adjusted odds ratio [aOR] 1.5; 95% confidence interval [95% CI]: 1.1-2.0), severe AECOPD (aOR 1.5; 95% CI: 1.1-2.2), dyspnea (mMRC ≥ 2 aOR 1.4; 95% CI: 1.0-1.9), respiratory symptoms (CAT ≥ 10 aOR 1.6; 95% CI: 1.1-2.4), and higher SGRQ score (β 2.7; 95% CI: 0.5, 5). Thrombocytosis was also associated with classification into Global Initiative for Chronic Obstructive Lung Disease (GOLD) group D (aOR 1.7 95% CI: 1.2-2.4).

CONCLUSIONS

Thrombocytosis was associated with higher likelihood of prior exacerbation and worse symptoms. Platelet count, a commonly measured clinical assay, may be a biomarker for moderate-severe COPD symptoms, guide disease classification and intensity of treatment. Future longitudinal studies investigating the role of platelets in COPD progression may be warranted.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01969344 (SPIROMICS) and NCT00608764 (COPDGene).

Platelets, inflammation and tissue regeneration

Blood platelets have long been recognised to bring about primary haemostasis with deficiencies in platelet production and function manifesting in bleeding while upregulated function favourises arterial thrombosis. Yet increasing evidence indicates that platelets fulfil a much wider role in health and disease. First, they store and release a wide range of biologically active substances including the panoply of growth factors, chemokines and cytokines released from α-granules. Membrane budding gives rise to microparticles (MPs), another active participant within the blood stream. Platelets are essential for the innate immune response and combat infection (viruses, bacteria, micro-organisms). They help maintain and modulate inflammation and are a major source of pro-inflammatory molecules (e.g. P-selectin, tissue factor, CD40L, metalloproteinases). As well as promoting coagulation, they are active in fibrinolysis; wound healing, angiogenesis and bone formation as well as in maternal tissue and foetal vascular remodelling. Activated platelets and MPs intervene in the propagation of major diseases. They are major players in atherosclerosis and related diseases, pathologies of the central nervous system (Alzheimers disease, multiple sclerosis), cancer and tumour growth. They participate in other tissue-related acquired pathologies such as skin diseases and allergy, rheumatoid arthritis, liver disease; while, paradoxically, autologous platelet-rich plasma and platelet releasate are being used as an aid to promote tissue repair and cellular growth. The above mentioned roles of platelets are now discussed.

CD40 signaling and hepatic steatosis: Unanticipated links

Obesity predisposes to an increased risk of nonalcoholic fatty liver disease (NAFLD). Hepatic steatosis is the key pathological feature of NAFLD and has emerged as a metabolic disorder in which innate and adaptive arms of the immune response play a central role in disease pathogenesis. Recent studies have revealed unexpected relationships between CD40 signaling and hepatic steatosis in high fat diet rodent models. CD154, the ligand of CD40, is a mediator of inflammation and controls several critical events of innate and adaptive immune responses. In the light of these reports, we discuss potential links between CD40 signaling and hepatic steatosis in NAFLD.

A Role for CD154, the CD40 Ligand, in Granulomatous Inflammation

Granulomatous inflammation is a distinctive form of chronic inflammation in which predominant cells include macrophages, epithelioid cells, and multinucleated giant cells. Mechanisms regulating granulomatous inflammation remain ill-understood. CD154, the ligand of CD40, is a key mediator of inflammation. CD154 confers a proinflammatory phenotype to macrophages and controls several macrophagic functions. Here, we studied the contribution of CD154 in a mouse model of toxic liver injury with carbon tetrachloride and a model of absorbable suture graft. In both models, granulomas are triggered in response to endogenous persistent liver calcified necrotic lesions or by grafted sutures. CD154-deficient mice showed delayed clearance of carbon tetrachloride-induced liver calcified necrotic lesions and impaired progression of suture-induced granuloma. In vitro, CD154 stimulated phagocytosis of opsonized erythrocytes by macrophages, suggesting a potential mechanism for the altered granulomatous inflammation in CD154KO mice. These results suggest that CD154 may contribute to the natural history of granulomatous inflammation.

Platelet expression of PKCepsilon oncoprotein in myelofibrosis is associated with disease severity and thrombotic risk

BACKGROUND

Myelofibrosis (MF) is the most aggressive Philadelphia-negative chronic myeloproliferative neoplasm (MPN) with high morbidity and mortality due to thrombo-hemorrhagic complications and leukemic transformation. MF is characterized by profound alterations of megakaryocytopoiesis, with consequent abnormalities in platelet number and function. We recently showed that the overexpression of the oncoprotein PKCepsilon plays a key role in the aberrant differentiation of MF megakaryocyte clone and that its levels correlate with disease burden. Moreover, our group previously demonstrated that PKCepsilon is over-expressed in platelets from patients with acute myocardial infarction (MI) and accounts for their increased reactivity. On these bases, we investigated here the activation state and PKCepsilon expression of MF platelets, testing potential correlations with thrombotic risk and disease aggressiveness.

METHODS

Platelets were isolated from peripheral blood samples of MF patients and healthy donors (HDs). Patients were stratified according to the IPSS/DIPSS risk category and history of cardiovascular events. Platelet activation was assessed by flow cytometry. PKCepsilon mRNA and protein levels were determined by real time-PCR and western blot.

RESULTS

MF platelets circulate in an activated status and display significantly higher levels of PKCepsilon compared to HDs. In MF patients, PKCepsilon platelet levels were associated with high-risk disease as well as with a positive history of major cardiovascular events.

CONCLUSIONS

PKCepsilon is configuring as the common denominator of neoplastic transformation and thrombus formation in MF. Overall, our data pinpoint PKCepsilon as a potential novel biomarker of disease aggressiveness and thrombotic risk in this hematologic neoplasm.

CD40L and Its Receptors in Atherothrombosis-An Update

CD40L (CD154), a member of the tumor necrosis factor superfamily, is a co-stimulatory molecule that was first discovered on activated T cells. Beyond its fundamental role in adaptive immunity-ligation of CD40L to its receptor CD40 is a prerequisite for B cell activation and antibody production-evidence from more than two decades has expanded our understanding of CD40L as a powerful modulator of inflammatory pathways. Although inhibition of CD40L with neutralizing antibodies has induced life-threatening side effects in clinical trials, the discovery of cell-specific effects and novel receptors with distinct functional consequences has opened a new path for therapies that specifically target detrimental properties of CD40L. Here, we carefully evaluate the signaling network of CD40L by gene enrichment analysis and its cell-specific expression, and thoroughly discuss its role in cardiovascular pathologies with a specific emphasis on atherosclerotic and thrombotic disease.

Do we need antiplatelet therapy in thrombocytosis? Contra. Proposal for an individualized risk-adapted treatment

Thrombocytosis is a frequent laboratory finding but not a diagnosis. Therefore, elevated platelet counts (>450 x 10⁹/l) require careful diagnostic work-up to differentiate between reactive thrombocytosis (RT), caused by various conditions, and essential thrombocythemia (ET), a myeloproliferative neoplasm (MPN). In either setting, aspirin is widely used in clinical practice. However, RT (even at platelet counts >1000 x 10⁹/l) has never been shown to cause thrombosis or bleeding due to acquired von Willebrand factor defects in association with high platelet counts. Identification of reactive conditions and appropriate therapy of the underlying disorder are most relevant. By contrast to RT, ET and related MPN can be associated with thrombosis and/or hemorrhage. Current recommendations suggest the use of low-dose aspirin in all patients with ET unless contraindicated. However, the strength of this recommendation is weak, i. e. evidence level IIb grade B. A potential benefit of aspirin used for primary thromboprophylaxis in ET is mostly derived from the ECLAP study in polycythemia vera (PV). However, translating study results from PV to ET appears to be highly questionable and may be biased. In the absence of robust data regarding the benefit-risk balance of aspirin in ET, it appears reasonable (1) to stratify patients according to their individual thrombotic and bleeding risk, (2) to restrict the use of aspirin to high-risk categories and patients with microcirculatory disturbances, (3) to test for pharmacological efficacy (COX-1 inhibition; measurement of TXB₂), and (4) to modify the aspirin dosing regimen (twice instead of once daily) if required.

Soluble B7-H2 as a novel marker in early evaluation of the severity of acute pancreatitis

The clinical usefulness of soluble B7-H2 (sB7-H2) as an early indicator of acute pancreatitis (AP) remains unclear, so we performed the present study to investigate this issue. For our cohort, we recruited 75 patients with AP, 70 patients with other abdominal sepsis, and 20 healthy control individuals. The sB7-H2 levels of AP patients or healthy control individuals were measured by enzyme-linked immunosorbent assay (ELISA). The sB7-H2 levels in patients with AP rather than other patients with abdominal sepsis were significantly higher than those in healthy controls. Hence, we selected AP to study the clinical significance of sB7-H2 in inflammatory conditions. The sB7-H2 level was positively correlated with the white blood cell (WBC) count and the lactate dehydrogenase (LDH), high-sensitivity C-reactive protein (hs-CRP), and lipopolysaccharide LPS levels (P <.05 for each). Receiver operating characteristic (ROC) analysis revealed that sB7-H2 can distinguish moderately severe acute pancreatitis (MSAP) and severe acute pancreatitis (SAP) from mildly acute pancreatitis (MAP) with 77.8% sensitivity and 80.0% specificity; and that the levels of sB7-H2 also can distinguish SAP from MSAP and MAP with 92.0% sensitivity and 86.0% specificity. The present results indicate that sB7-H2 might be a useful marker in the clinical diagnosis of AP.

Effect of Danhong Injection Combined with Naoxintong Tablets on Prognosis and Inflammatory Factor Expression in Acute Coronary Syndrome Patients Undergoing Percutaneous Coronary Intervention

BACKGROUND

Danhong is a Chinese medical component that has been broadly used to treat various cerebrovascular diseases. This work aimed to investigate the effect of Danhong injection combined with Naoxintong tablets on the short-term prognosis and expression of inflammatory factor-soluble CD40 ligand (sCD40L) in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI).

METHODS

A total of 100 ACS patients with PCI were randomly divided equally into treatment and control groups. The control group was treated with conventional secondary prevention of coronary heart disease. Based on secondary prevention, Danhong injection combined with Naoxintong tablets was administered in the treatment group. The incidences of major adverse cardiovascular events and cardiac functions, including ejection fraction (EF) and six-minute walk test distance, during hospital discharge and at the third postoperative month were observed. The serum sCD40 levels at different times were also noted.

RESULTS

There were 2 patients in the treatment group and 7 in the control group that were lost during follow-up, so the collected data were from only 48 patients in the treatment and 43 in the control group. During hospital discharge and at the third postoperative month, no significant difference in death, myocardial infarction, stroke, angina pectoris and readmission were observed between the two groups (p > 0.05). Upon hospital discharge, EF, six-minute walk test distance and serum sCD40L level in the two groups were not significantly different (p > 0.05). At the third postoperative month, EF and six-minute walk test distance in treatment group were significantly higher than those in the control group (p < 0.05), and the serum sCD40L level in the treatment group was significantly lower than that in the control group (p < 0.01). In addition, serum sCD40L levels in the two groups at the third postoperative month were significantly lower than those during hospital discharge (p < 0.01).

CONCLUSIONS

Danhong injection combined with Naoxintong tablets decreased serum sCD40L level and improved cardiac functions in ACS patients undergoing PCI at 3 months following discharge, but not at discharge.

KEY WORDS

Acute coronary syndrome; Danhong injection; Naoxintong tablets; sCD40.

Immune Response to Dengue Virus Infection in Pediatric Patients in New Delhi, India--Association of Viremia, Inflammatory Mediators and Monocytes with Disease Severity

Dengue virus, a mosquito-borne flavivirus, is a causative agent for dengue infection, which manifests with symptoms ranging from mild fever to fatal dengue shock syndrome. The presence of four serotypes, against which immune cross-protection is short-lived and serotype cross-reactive antibodies that might enhance infection, pose a challenge to further investigate the role of virus and immune response in pathogenesis. We evaluated the viral and immunological factors that correlate with severe dengue disease in a cohort of pediatric dengue patients in New Delhi. Severe dengue disease was observed in both primary and secondary infections. Viral load had no association with disease severity but high viral load correlated with prolonged thrombocytopenia and delayed recovery. Severe dengue cases had low Th1 cytokines and a concurrent increase in the inflammatory mediators such as IL-6, IL-8 and IL-10. A transient increase in CD14⁺CD16⁺ intermediate monocytes was observed early in infection. Sorting of monocytes from dengue patient peripheral blood mononuclear cells revealed that it is the CD14+ cells, but not the CD16+ or the T or B cells, that were infected with dengue virus and were major producers of IL-10. Using the Boruta algorithm, reduced interferon-α levels and enhanced aforementioned pro-inflammatory cytokines were identified as some of the distinctive markers of severe dengue. Furthermore, the reduction in the levels of IL-8 and IL-10 were identified as the most significant markers of recovery from severe disease. Our results provide further insights into the immune response of children to primary and secondary dengue infection and help us to understand the complex interplay between the intrinsic factors in dengue pathogenesis.

Dengue virus is a human pathogen that causes dengue fever, which can either resolve after mild fever or lead to severe dengue hemorrhagic fever/dengue shock syndrome. The role of dengue virus levels in the blood and the kinetics of infection and immune response that results in severe dengue disease in humans is not well characterized. In this study, we analyzed 97 children with varying degrees of dengue disease, and we show that the dengue virus quantity in blood does not show any significant association with severe disease. However, most severe dengue patients had lower levels of interferons and Th1 cytokines and increased levels of secreted factors such as IL-6, IL-8 and IL-10 that could potentially cause leakage in blood capillaries. Our results indicate that monocytes, which are infected with dengue virus in patients, could possibly play a major role in dengue pathogenesis. Furthermore, using computational analysis we identified association of some of the secreted factors with severe disease and also predicted the markers that could serve as indicators of recovery from severe dengue.

Lysyl oxidase is associated with increased thrombosis and platelet reactivity

Lysyl oxidase (LOX) is overexpressed in various pathologies associated with thrombosis, such as arterial stenosis and myeloproliferative neoplasms (MPNs). LOX is elevated in the megakaryocytic lineage of mouse models of MPNs and in patients with MPNs. To gain insight into the role of LOX in thrombosis and platelet function without compounding the influences of other pathologies, transgenic mice expressing LOX in wild-type megakaryocytes and platelets (Pf4-Lox(tg/tg)) were generated. Pf4-Lox(tg/tg) mice had a normal number of platelets; however, time to vessel occlusion after endothelial injury was significantly shorter in Pf4-Lox(tg/tg) mice, indicating a higher propensity for thrombus formation in vivo. Exploring underlying mechanisms, we found that Pf4-Lox(tg/tg) platelets adhere better to collagen and have greater aggregation response to lower doses of collagen compared with controls. Platelet activation in response to the ligand for collagen receptor glycoprotein VI (cross-linked collagen-related peptide) was unaffected. However, the higher affinity of Pf4-Lox(tg/tg) platelets to the collagen sequence GFOGER implies that the collagen receptor integrin α2β1 is affected by LOX. Taken together, our findings demonstrate that LOX enhances platelet activation and thrombosis.

Multiplex Analysis of Serum Cytokines in Humans with Hantavirus Pulmonary Syndrome

Hantavirus pulmonary syndrome (HPS) is an acute zoonotic disease transmitted primarily through inhalation of virus-contaminated aerosols. Hantavirus infection of endothelial cells leads to increased vascular permeability without a visible cytopathic effect. For this reason, it has been suggested that the pathogenesis of HPS is indirect with immune responses, such as cytokine production, playing a dominant role. In order to investigate their potential contribution to HPS pathogenesis, we analyzed the serum of hantavirus-infected subjects and healthy controls for 68 different cytokines, chemokines, angiogenic, and growth factors. Our analysis identified differential expression of cytokines that promote tissue migration of mononuclear cells including T lymphocytes, natural killer cells, and dendritic cells. Additionally, we observed a significant upregulation of cytokines known to regulate leukocyte migration and subsequent repair of lung tissue, as well as cytokines known to increase endothelial monolayer permeability and facilitate leukocyte transendothelial migration. Conversely, we observed a downregulation of cytokines associated with platelet numbers and function, consistent with the thrombocytopenia observed in subjects with HPS. This study corroborates clinical findings and extends our current knowledge regarding immunological and laboratory findings in subjects with HPS.

Platelet counts as a biomarker in ANCA-associated vasculitis

OBJECTIVES

To determine whether platelet (PLT) counts might serve as a biomarker to distinguish between active anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and remission and also between active disease and systemic infection.

METHOD

PLTs were analysed before treatment in patients with AAV in the active state and in remission. PLTs were also analysed in AAV patients with acute infections. The results were correlated with clinical manifestations, the Birmingham Vasculitis Activity Score version 3 [BVAS(v.3)], and other laboratory findings [i.e. C-reactive protein (CRP), leucocytes, differential count, procalcitonin (PCT)]. Diagnostic accuracy was calculated with a receiver operating characteristic (ROC) curve.

RESULTS

PLT counts were significantly increased in 98 patients with AAV during the active disease state [median: 405 PLTs/nL; interquartile range (IQR) 288-504] compared to patients in remission (246 PLT/nL; IQR 214-289) (p < 0.001). We found a correlation of PLT counts in active disease with the BVAS(v.3) (r = 0.582, p < 0.001). In AAV patients with systemic infections (n = 37), PLT counts exhibited significantly lower values (226 PLT/nL; IQR 163-273) compared to patients with active disease (p < 0.001). In the ROC curve analysis, the area under the curve (AUC) of PLTs was significantly larger when distinguishing active disease from systemic infection (AUC 0.868) compared to leucocytes (AUC 0.590), CRP (AUC 0.522), or procalcitonin (AUC 0.515) (p < 0.001).

CONCLUSIONS

PLT counts were found to correlate with disease activity in AAV and thus may be used to represent immunological activity. In addition, PLT counts serve as a marker that can distinguish acute infection from active disease.

New frontiers for platelet CD154

The role of platelets extends beyond hemostasis. The pivotal role of platelets in inflammation has shed new light on the natural history of conditions associated with acute or chronic inflammation. Beyond the preservation of vascular integrity, platelets are essential to tissue homeostasis and platelet-derived products are already used in the clinics. Unanticipated was the role of platelets in the adaptative immune response, allowing a renewed conceptual approach of auto-immune diseases. Platelets are also important players in cancer growth and dissemination. Platelets fulfill most of their functions through the expression of still incompletely characterized membrane-bound or soluble mediators. Among them, CD154 holds a peculiar position, as platelets represent a major source of CD154 and as CD154 contributes to most of these new platelet attributes. Here, we provide an overview of some of the new frontiers that the study of platelet CD154 is opening, in inflammation, tissue homeostasis, immune response, hematopoiesis and cancer.

Soluble CD40-ligand (sCD40L, sCD154) plays an immunosuppressive role via regulatory T cell expansion in HIV infection

CD40/CD40-ligand (CD40L) signalling is a key stimulatory pathway which triggers the tryptophan (Trp) catabolizing enzyme IDO in dendritic cells and is immunosuppressive in cancer. We reported IDO-induced Trp catabolism results in a T helper type 17 (Th17)/regulatory T cell (Treg ) imbalance, and favours microbial translocation in HIV chronic infection. Here we assessed the link between sCD40L, Tregs and IDO activity in HIV-infected patients with different clinical outcomes. Plasmatic sCD40L and inflammatory cytokines were assessed in anti-retroviral therapy (ART)-naive, ART-successfully treated (ST), elite controllers (EC) and healthy subjects (HS). Plasma levels of Trp and its metabolite Kynurenine (Kyn) were measured by isotope dilution tandem mass spectrometry and sCD14 was assessed by enzyme-linked immunosorbent assay (ELISA). IDO-mRNA expression was quantified by reverse transcription-polymerase chain reaction (RT-PCR). The in-vitro functional assay of sCD40L on Treg induction and T cell activation were assessed on peripheral blood mononuclear cells (PBMCs) from HS. sCD40L levels in ART-naive subjects were significantly higher compared to ST and HS, whereas EC showed only a minor increase. In ART-naive alone, sCD40L was correlated with T cell activation, IDO-mRNA expression and CD4 T cell depletion but not with viral load. sCD40L was correlated positively with IDO enzymatic activity (Kyn/Trp ratio), Treg frequency, plasma sCD14 and inflammatory soluble factors in all HIV-infected patients. In-vitro functional sCD40L stimulation induced Treg expansion and favoured Treg differentiation by reducing central memory and increasing terminal effector Treg proportion. sCD40L also increased T cell activation measured by co-expression of CD38/human leucocyte antigen D-related (HLA-DR). These results indicate that elevated sCD40L induces immunosuppression in HIV infection by mediating IDO-induced Trp catabolism and Treg expansion.

The signaling role of CD40 ligand in platelet biology and in platelet component transfusion

The CD40 ligand (CD40L) is a transmembrane molecule of crucial interest in cell signaling in innate and adaptive immunity. It is expressed by a variety of cells, but mainly by activated T-lymphocytes and platelets. CD40L may be cleaved into a soluble form (sCD40L) that has a cytokine-like activity. Both forms bind to several receptors, including CD40. This interaction is necessary for the antigen specific immune response. Furthermore, CD40L and sCD40L are involved in inflammation and a panoply of immune related and vascular pathologies. Soluble CD40L is primarily produced by platelets after activation, degranulation and cleavage, which may present a problem for transfusion. Soluble CD40L is involved in adverse transfusion events including transfusion related acute lung injury (TRALI). Although platelet storage designed for transfusion occurs in sterile conditions, platelets are activated and release sCD40L without known agonists. Recently, proteomic studies identified signaling pathways activated in platelet concentrates. Soluble CD40L is a good candidate for platelet activation in an auto-amplification loop. In this review, we describe the immunomodulatory role of CD40L in physiological and pathological conditions. We will focus on the main signaling pathways activated by CD40L after binding to its different receptors.

Dkk3 levels in patients with myeloproliferative neoplasms

INTRODUCTION

Dickkopf-3 (Dkk3) has been proposed as tumor suppressor gene and a marker for tumor blood vessels and has pro-angiogenic properties. Dkk3 is expressed in platelets and megakaryocytes from healthy controls and patients with BCR-ABL1-negative myeloproliferative neoplasms (MPN). The aim of this study is, to find out whether patients with MPN have higher Dkk3 serum levels than normal controls.

MATERIAL & METHODS

We analyzed Dkk3 serum levels with ELISA in patients with newly diagnosed and untreated MPN, including 10 essential thrombocythemia (ET), 10 polycythemia vera (PV), 10 primary meylofibrosis (PMF) and 10 healthy blood donors and correlated these findings with biological and clinical key data and the JAK2-V617F status. Dkk3 levels were corrected to platelet count, Dkk3c, as patients with MPN have higher platelet counts than controls.

RESULTS

As expected, patients with MPN have higher platelet counts than normal controls. Dkk3 serum levels of patients with MPN (5.4 ± 6.1 ng/ml) showed no significant difference compared to normal controls (4.4 ± 3.8 ng/ml). Regarding Dkk3c, a significant difference to controls was found in PV (8.5 ± 8.7 ng/ml; p=0.04), but not in ET and PMF (5.7 ± 3.8 ng/ml; p=0.07 and 2.7 ± 3.6 ng/ml; p=0.9; respectively. Dkk3c correlated with the JAK2-V617F mutational burden (p=0.014, Rho=0.445).

CONCLUSION

Dkk3 levels corrected to platelet count showed higher levels in PV than normal controls. Elevated Dkk3c level could possibly correlate to platelet activation in PV patients and increased Dkk3 release. Whether this remains a surrogate marker of platelet release or it contributes to the thrombophilic state through its pro-angiogenic properties remains to be shown.

Synthetic isoxazole as antiplatelet agent

Abstract Nine synthetic isoxazoles were evaluated as antiplatelet agents and studied the possible mechanism of more active compound. The initial screening was evaluating all compounds against platelet aggregation assays. The most active compound was isoxazole 8 showing an inhibition of platelet aggregation around 70%. In subsequent experiments, ADP and collagen were used as agonists to explore the possible inhibitory mechanisms of isoxazole 8 in platelet aggregation and secretion. We reported the effect of isoxazole 8 for reducing the expression of inflammatory markers, such as soluble CD40 ligand (sCD40L) and soluble P-selectin (sP-selectin), on activated platelets. Of this form, an inhibition of sCD40L and sP-selectin can prevent the onset of an atherosclerotic lesion.

Increased PD-1 on CD4(+)CD28(-) T cell and soluble PD-1 ligand-1 in patients with T2DM: association with atherosclerotic macrovascular diseases

OBJECTIVE

To study the role of the programmed death-1 (PD-1)/programmed death-1 ligand 1 (PD-L1) coinhibitory pathway in regulating CD4(+)CD28(-) T cells, and to explore the association of soluble PD-L1 (sPD-L1) in the development of T2DM with atherosclerotic macrovascular diseases.

METHODS

The percentage of CD4(+)CD28(-) T lymphocyte subsets from peripheral blood mononuclear cells (PBMCs) and the expression of PD-1/PD-L1 on lymphocytes were analyzed by immunostaining and flow cytometry, respectively. The serum levels of sPD-L1 and IFN-γ were determined by ELISA system. T cell proliferation was determined by cocultivation and WST-8 incorporation.

RESULTS

In 125 T2DM patients and 48 healthy donors, CD4(+)CD28(-) T cells from patients with T2DM expressed higher PD-1 than that of the cells from healthy individuals, and the proliferation response of CD4(+)CD28(-) T cells could be enhanced by advanced glycation end products (AGEs). The levels of sPD-L1 in patients were also much higher than those of healthy donors, and the increase was displayed in an exacerbation-dependent manner in the T2DM with atherosclerotic macrovascular patients especially with acute coronary syndrome (ACS). The production of sPD-L1 was significantly positively correlated with the level of IFN-γ and could enhance T cell proliferation.

CONCLUSION

Both the upregulation of PD-1 and the increase of sPD-L1 were closely associated with the severity of diabetic atherosclerotic macrovascular diseases. sPD-L1 may contribute to the continuous T cell activation and development of diabetic macrovascular diseases.

Platelet activation and inhibition in polycythemia vera and essential thrombocythemia

Persistently enhanced platelet activation has been characterized in polycythemia vera (PV) and essential thrombocythemia (ET) and shown to contribute to a higher risk of both arterial and venous thrombotic complications. The incidence of major bleeding complications is also somewhat higher in PV and ET than in the general population. Although its efficacy and safety was assessed in just 1 relatively small trial in PV, low-dose aspirin is currently recommended in practically all PV and ET patients. Although for most patients with a thrombosis history the benefit/risk profile of antiplatelet therapy is likely to be favorable, in those with no such history this balance will depend critically on the level of thrombotic and hemorrhagic risks of the individual patient. Recent evidence for a chemopreventive effect of low-dose aspirin may tilt the balance of benefits and harm in favor of using aspirin more broadly, but the potential for additional benefits needs regulatory scrutiny and novel treatment guidelines. A clear pharmacodynamic rationale and analytical tools are available for a personalized approach to antiplatelet therapy in ET, and an improved regimen of low-dose aspirin therapy should be tested in a properly sized randomized trial.