Indicator Of Platelet Activation Research Articles

Mean Platelet Volume in Women with Gestational Diabetes

Purpose: Mean platelet volume (MPV) is an indicator of platelet activation which plays an important role in the pathogenesis of atherosclerosis. The purpose of this study was to compare MPV values in patients with previous gestational diabetes (pGDM), who have different degrees of carbohydrate intolerance with that in women without pGDM; and to retrospectively analyze MPV in these women during pregnancy. Material and Method: One hundred and five consecutive women with gestational diabetes mellitus (GDM) and 40 women with negative screening for GDM were studied. Results: There was no statistically significant difference in MPV between women with pGDM and health controls. Although not significant, women with pGDM developing type 2 diabetes had elevated levels of MPV compared to their normoglycemic counterparts (p=0.092). MPV was positively correlated with fasting glucose levels (r=0.215, p=0.009). During pregnancy, the mean platelet volume was significantly higher in women with GDM than in healthy pregnant controls (p<0.05). Discussion: Our results suggest that alterations in MPV levels are associated with diabetic state rather than underlying insulin resistance.

Mean Platelet Volume During Ischemic Stroke is a Potential Pro-inflammatory Biomarker in the Acute Phase and During Neurorehabilitation Not Directly Linked to Clinical Outcome.

The prognostic role of increased mean platelet volume (MPV), as an indicator of platelet activation and large, more reactive platelets, in clinical and functional outcome of ischemic stroke is still conflicting. Studies are not currently available on the association between MPV and stroke recovery after neurorehabilitation. The relationship between MPV and clinical and functional outcome measures was assessed in twenty-four patients in the acute phase of first-ever ischemic stroke, and before and after 8-week intensive multifunctional neurorehabilitation. Neurorehabilitation was associated with improved scores of the National Institutes of Health Stroke Scale (NIHSS), the modified Rankin Scale (mRS), and the modified PULSES profile (mPULSES). When compared with apparently healthy subjects, higher MPV values were observed in stroke patients 24 hours after stroke and before neurorehabilitative treatment started not later than 14 days after stroke. Decreased MPV values were found after neurorehabilitation, even if the absolute values were still higher than those detected in control subjects. No correlation was observed between MPV values and scores of the NIHSS and mRS scales evaluated in stroke acute phase. No correlation was also observed before and after neurorehabilitative treatment between MPV and NIHSS, mRS and mPULSES scores. Our data provide evidence of the effectiveness of neurorehabilitation on modulating MPV values and support the hypothesis that high MPV could represent an expression of proinflammatory condition of the stroke patients, realistically pre-existent to acute ischemic event, than a marker of neurologic deficit and disability or of stroke recovery including motor performance and functional independence.

Association of Soluble CD40 Ligand WithDuration of Atrial Fibrillation andWith Intensity of Spontaneous Echocardiographic Contrast.

The authors tested the hypothesis that the inflammatory response of nonvalvular atrial fibrillation (NVAF) is associated with elevated soluble CD40 ligand (sCD40L). NVAF is generally believed to be an inflammatory disease process. sCD40L represents a sensitive invivo indicator of platelet activation and may serve as an "inflammatory and thrombotic thermometer." Plasma sCD40L was measured using enzyme-linked immunoadsorbent assay in 109 NVAF cases (60.9 ± 15 years of age; 26% women) and 48normal sinus rhythm (NSR) controls (62.3 ± 15 years of age; 44% women). Patients were separated by arrhythmia duration of<1 month (n= 21), 1 to 12 months (n= 18), and >12 months (n= 70). Median sCD40L level was significantly higher in NVAF cases than in NSR controls (321 pg/ml vs. 238 pg/ml, respectively; p= 0.029). This difference was driven by higher levels in patients with NVAF duration for<1 month (552pg/ml) and 1 to 12 months (328 pg/ml). NVAF patients with arrhythmia duration for over 1 year had sCD40L levels not significantly different from those of NSR controls. An sCD40L concentration of 552 pg/ml distinguished NVAF patients with dysrhythmia duration of<1 month (area under the curve [AUC] of 0.72; p= 0.0010) or duration for ≤12months (AUC: 0.69; p= 0.0003) from NSR controls. Circulating sCD40L levels were also significantly higher among patients with mild spontaneous echocardiogram contrast (SEC) (p= 0.0378) and those with moderate SEC (p= 0.007) compared with NSR controls. sCD40L levels are significantly higher in NVAF patients than in NSR controls but only for up to 1 year after development of dysrhythmia. An sCD40L concentration of 552 pg/ml can help to assess development or recurrence of asymptomatic NVAF.

Evaluation of flow cytometric HIT assays in relation to an IgG-Specific immunoassay and clinical outcome.

Heparin-induced thrombocytopenia (HIT) is a severe side effect of heparin treatment caused by platelet activating IgG antibodies generated against the platelet factor 4 (PF4)-heparin complex. Thrombocytopenia and thrombosis are the leading clinical symptoms of HIT. The clinical pretest probability of HIT was evaluated by the 4T score system. Laboratory testing of HIT was performed by immunological detection of antibodies against PF4-heparin complex (EIA) and two functional assays. Heparin-dependent activation of donor platelets by patient plasma was detected by flow cytometry. Increased binding of Annexin-V to platelets and elevated number of platelet-derived microparticles (PMP) were the indicators of platelet activation. EIA for IgG isotype HIT antibodies was performed in 405 suspected HIT patients. Based on negative EIA results, HIT was excluded in 365 (90%) of cases. In 40 patients with positive EIA test result functional tests were performed. Platelet activating antibodies were detected in 17 cases by Annexin V binding. PMP count analysis provided nearly identical results. The probability of a positive flow cytometric assay result was higher in patients with elevated antibody titer. 71% of patients with positive EIA and functional assay had thrombosis. EIA is an important first line laboratory test in the diagnosis of HIT; however, HIT must be confirmed by a functional test. Annexin V binding and PMP assays using flow cytometry are functional HIT tests convenient in a clinical diagnostic laboratory. The positive results of functional assays may predict the onset of thrombosis. © 2016 International Clinical Cytometry Society.

Blockade of Thrombopoietin Reduces Organ Damage in Experimental Endotoxemia and Polymicrobial Sepsis.

Background and PurposeThrombopoietin (TPO), a growth factor primarily involved in thrombopoiesis may also have a role in the pathophysiology of sepsis. In patients with sepsis, indeed, TPO levels are markedly increased, with disease severity being the major independent determinant of TPO concentrations. Moreover, TPO increases and correlates with ex vivo indices of platelet activation in patients with burn injury upon sepsis development, and may contribute to depress cardiac contractility in septic shock. Still, the role of TPO in sepsis pathophysiology remains controversial, given the protective role of TPO in other experimental disease models, for instance in doxorubicin-induced cardiotoxicity and myocardial ischemia/reperfusion injury. The aim of our study was to define the contribution of TPO in the development of organ damage induced by endotoxemia or sepsis, and to investigate the effects of inhibiting TPO in these conditions.MethodsWe synthesized a chimeric protein able to inhibit TPO, mTPOR-MBP, and studied its effect in two murine experimental models, acute endotoxemia and cecal ligation and puncture (CLP) model.ResultsIn both models, TPO levels markedly increased, from 289.80±27.87 pg/mL to 465.60±45.92 pg/mL at 3 hours in the LPS model (P<0.01), and from 265.00±26.02 pg/mL to 373.70±26.20 pg/mL in the CLP model (P<0.05), respectively. Paralleling TPO levels, also platelet-monocyte aggregates increased, from 32.86±2.48% to 46.13±1.39% at 3 hours in the LPS model (P<0.01), and from 43.68±1.69% to 56.52±4.66% in the CLP model (P<0.05). Blockade of TPO by mTPOR-MBP administration reduced histological damage in target organs, namely lung, liver, and gut. In particular, neutrophil infiltration and lung septal thickening were reduced from a score of 1.86±0.34 to 0.60±0.27 (P<0.01) and from 1.43±0.37 to 0.40±0.16 (P<0.05), respectively, in the LPS model at 3 hours, and from a score of 1.75±0.37 to 0.38±0.18 (P<0.01) and from 1.25±0.31 to 0.13±0.13 (P<0.001), respectively, in the CLP model. Similarly, the number of hepatic microabscesses was decreased from 14.14±1.41 to 3.64±0.56 in the LPS model at 3 hours (P<0.001), and from 1.71±0.29 to 0.13±0.13 in the CLP model (P<0.001). Finally, the diameter of intestinal villi decreased from 90.69±3.95 μm to 70.74±3.60 μm in the LPS model at 3 hours (P<0.01), and from 74.29±4.29 μm to 57.50±1.89 μm in the CLP model (P<0.01). This protective effect was associated with the blunting of the increase in platelet-monocyte adhesion, and, on the contrary, with increased platelet-neutrophil aggregates in the circulation, which may be related to decreased neutrophil sequestration into the inflamed tissues. Conversely, circulating cytokine levels were not significantly changed, in both models, by mTPOR-MBP administration.ConclusionOur results demonstrate that TPO participates in the development of organ damage induced by experimental endotoxemia or polymicrobial sepsis via a mechanism involving increased platelet-leukocyte adhesion, but not cytokine release, and suggest that blocking TPO may be useful in preventing organ damage in patients affected by systemic inflammatory response or sepsis.

Platelet activation and cardiovascular comorbidities in patients with chronic obstructive pulmonary disease

Objective Platelet activation in COPD patients is associated with an increased risk of cardiovascular events. We aimed at assessing the mean platelet volume (MPV), as an index of platelet activation, in COPD patients both when stable or during acute exacerbation (AE).Research design and methods A total of 478 patients (75 with AE) and 72 age-matched healthy controls were enrolled. Medical history, comorbidities, medications, pulmonary function tests, MPV and blood cell count, erythrocyte sedimentation rate (ERS) and C-reactive protein (CRP) were recorded.Results MPV was higher in COPD than in controls (8.7 ± 1.1 fL and 8.4 ± 0.8 fL respectively, p = 0.025) and increased with the severity of the disease as assessed by post-bronchodilator forced expiratory volume in the first second (FEV1) categorized I to IV (p > 0.05). MPV was higher in COPD patients during AE compared with stable condition (8.7 ± 1.0 fL and 8.9 ± 1.0 fL, p = 0.021). MPV ≥10.5 fL correlated with the presence of at least one co-existing cardiovascular disease (p = 0.008). No correlation was observed between MPV and CRP or ERS in patients or in controls. A negative correlation was found between platelet count and MPV in COPD patients.Limitations The retrospective design did not allow the assessment of a clear cause–effect relationship between MPV and all the pathophysiological factors considered.Conclusions Elevated MPV is associated with lower platelet count and with cardiovascular comorbidity in COPD patients. MPV is higher in more severe COPD and during AE. Present findings warrant future studies to confirm a possible clinically relevant role for platelet activation in cardiovascular risk in the COPD population.

Mean Platelet Volume in Patients with Chronic Venous Insufficiency

Objective: the mean platelet volume (MPV) is a good indicator of platelet activity; it is reported to increase in diseases associated with inflammatory processes and in vascular diseases. This study investigated the importance of mean platelet volume in patients with chronic venous insufficiency (CVI) and whether the MPV was likely to be a predictor of the CVI. Methods: 117 patients who were diagnosed as CVI by colored Doppler Ultrasound (CDU) method and 49 healthy volunteers (forming the control group) were en­rolled to this study, which was planned retrospectively. The patients’ blood count values taken within one month before and after the CDU evaluation were recorded by the hospital information system. The complete blood count, routine biochemical tests and thyroid function tests of the patients diagnosed with CVI were compared to the control group. Results: Significant differences were not detected be­tween the patients and the control group in terms of the levels of creatinine, aspartate aminotransferase, total cholesterol, LDL cholesterol, HDL cholesterol, triglycer­ides, erythrocyte, sedimentation speed, leukocyte, hae­moglobin and thrombocyte (p>0.05). The thyroid stimulat­ing hormone and the MPV levels were significantly lower in the control group (p<0.05). Conclusion: MPV levels as an easy, cheap and practi­cal data extracted from complete blood count, were found higher in patients diagnosed with CVI compared to the control group. This may be originated from endothelium changes as an answer to venous hypertension and dila­tation in CVI. MPV can be used as a follow-up marker in CVI patients.

Mean Platelet Volume in Patients with Chronic Venous Insufficiency

Objective: the mean platelet volume (MPV) is a good indicator of platelet activity; it is reported to increase in diseases associated with inflammatory processes and in vascular diseases. This study investigated the importance of mean platelet volume in patients with chronic venous insufficiency (CVI) and whether the MPV was likely to be a predictor of the CVI. Methods: 117 patients who were diagnosed as CVI by colored Doppler Ultrasound (CDU) method and 49 healthy volunteers (forming the control group) were enrolled to this study, which was planned retrospectively. The patients’ blood count values taken within one month before and after the CDU evaluation were recorded by the hospital information system. The complete blood count, routine biochemical tests and thyroid function tests of the patients diagnosed with CVI were compared to the control group. Results: Significant differences were not detected between the patients and the control group in terms of the levels of creatinine, aspartate aminotransferase, total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, erythrocyte, sedimentation speed, leukocyte, haemoglobin and thrombocyte (p>0.05). The thyroid stimulating hormone and the MPV levels were significantly lower in the control group (p<0.05). Conclusion: MPV levels as an easy, cheap and practical data extracted from complete blood count, were found higher in patients diagnosed with CVI compared to the control group. This may be originated from endothelium changes as an answer to venous hypertension and dilatation in CVI. MPV can be used as a follow-up marker in CVI patients. J Clin Exp Invest 2016; 7 (1): 73-77

Is signal peptide-CUB-EGF domain-containing protein1 a diagnostic biomarker in patients with hypertensive crises.

Platelet activation might play a significant role in the pathophysiology of cardiovascular and cerebrovascular events in hypertension (HT). Signal peptide-CUB-EGF domain-containing protein1 (SCUBE1), an indicator of platelet activation, is increased in HT. The aim of this study was to investigate the SCUBE1 in patients with hypertensive crises. This study included 33 hypertensive urgency (HU) and 39 hypertensive emergency (HI) patients admitted to our emergency department with a diagnosis of hypertensive crisis. Platelet activation was evaluated with biochemical markers such as SCUBE1, soluble CD40L (sCD40L), mean platelet volume, and platelet count. The SCUBE1 values of the HE patients were significantly higher than other groups (1.09 ± 0.49, 0.71 ± 0.23 and 0.37 ± 0.02 ng/dl, respectively; p < 0.01). The sCD40L values were higher in the hypertensive crises compared with the control group (4.16 ± 1.82, 3.41 ± 1.76 and 1.76 ± 0.68 ng/ml, respectively; p < 0.01). More importantly, SCUBE1 had high sensitivity and specificity in the detection of target organ damage. In present study showed that SCUBE1 was significantly higher in HE patients. In addition, sCD40L level, presence of diabetes, and systolic blood pressure were independently associated with increased SCUBE1. According to our results, SCUBE1 might be a diagnostic biomarker in hypertensive crisis patients.

Mean Platelet Volume in Mycobacterium tuberculosis Infection.

Introduction. Mean platelet volume (MPV) has been thought as a useful index of platelet activation. It is supposed that MPV is also associated with several inflammatory and infectious diseases. Korea still has a high incidence of tuberculosis (TB). The aim of this study was to investigate MPV as an inflammatory marker in TB patients. Materials and Methods. MPV were determined in 221 patients with TB and 143 individuals for control group. MPV was estimated by an Advia 2120 (Siemens Healthcare Diagnostics, Tarrytown, NY, USA). Results. In the TB patient group, a positive correlation was found between CRP and MPV. Age and MPV had a positive correlation in TB patient group. Conclusions. We conclude that there is a significant relation between MPV and inflammatory conditions. MPV can be an inflammatory marker to determine the disease activity in TB patients.

Assessment of Mean Platelet Volume and its Effect on Disease Control in Patients with Acromegaly.

Morbidity and mortality rates due to cardiovascular diseases are more common in acromegalic patients than the healthy population. Platelets play a significant role in both the onset and progression of clotting which then cause the development of atherosclerotic plaques. Increased mean platelet volume (MPV) is an indicator of platelet activation and known as an independent risk factor for atherosclerotic processes. The aim of this study was to compare MPV levels between acromegalic and non-acromegalic patients. The data of 56 acromegalic patients and 72 controls matched for age, gender, and the presence of diabetes were retrospectively reviewed. MPV levels were found to be higher in acromegalic patients compared to controls (8.82 ± 1.17 fL and 7.74 ± 0.87 fL, respectively, p < 0.001). Acromegalic patients were also classified according to their status of remission (a total of 27 patients were in remission and 29 patients were not in remission). Both age and gender were similar between the groups (p = 0.145 and p = 0.616, respectively). MPV levels at the time of diagnosis and after six months of treatment (p = 0.555 and p = 0.917, respectively) were not statistically significant. Our results suggest that MPV levels are higher in acromegalic patients than the controls until the early stages of treatment, independent of diabetes. Therefore, MPV levels may be an important determinant of acromegalic patients.

Could Mean Platelet Volume Be a Reliable Indicator for Acute Mesenteric Ischemia Diagnosis? A Case-Control Study.

Objective. Acute mesenteric ischemia (AMI) is a disease, usually seen in elderly people and accompanied by comorbid diseases. Mean platelet volume (MPV), the significant indicator of platelet activation and function, is associated with AMI. In this study, we considered that we can use MPV as a reliable indicator in the diagnosis of AMI. Methods. This study was conducted among AMI patients with two control groups. Age, gender, MPV, platelet count, concomitant diseases, abdominal computed tomography, and patient outcomes were recorded for evaluation. Control group I contained 41 healthy patients whose ages-genders were matched. Control group II contained 41 patients with no AMI, whose ages-genders-concomitant diseases were matched. Results. Of the total 41 AMI patients, 22 were female and 19 were male. The average age of them was 72.12 ± 13.2 (44–91) years. MPV was significantly increased in the AMI (p = 0.001) and control group II (p < 0.001) in comparison with healthy control groups. In the comparison of the AMI patients with their matched controls for concomitant diseases, no statistical difference was found in the MPV values. Conclusion. MPV may be used as an indicator of AMI only if the patient has no concomitant diseases. The existence of a concomitant disease brings into question the reliability of high MPV values as a suitable indicator.

TLR2-PI3K/Akt Signaling Pathway Involved in Platelet Activation Induced By Group B Streptococci

BackgroundPlatelets not only play an important role in the initiation of hemostasis and thrombosis, but also participate in the immune and inflammatory response. Most studies focus on the platelets-bacteria interaction and demonstrate that bacteria are capable of binding to, aggregating and activating platelets. Human platelets are reported to express several groups of TLRs, which participate in the inflammation process and monitoring host infection. Recent data from our laboratory demonstrated that Group B streptococci (GBS) could induce platelet aggregation and up-regulate the expression of CD62P and further study showed that platelet TLR2 might involve in the activation. GBS, or streptococcus agalactiae, is one of the most common cause of life-threatening sepsis, pneumonia and meningitis in neonates, pregnant women, the elderly and immunocompromised adults. Therefore, illuminating the mechanisms of GBS-induced platelet activation is important for providing the basis for platelets in defense against infection and immunity. Since increasing reports have shown that the PI3-K/Akt signaling pathway regulates platelet activation and hemostasis, so it is possible to research the TLR2 related signaling pathway.Methods1. Platelets were from healthy volunteers (all genders, 25-52 years old) who had not taken any anti-platelet drugs (like aspirins, clopidogrel and abciximab) during the previous 30 days. GBS 639 were isolated from patient's venous blood.2. Platelet aggregation, the expression of platelet CD62P and PAC-1 were used as the indicator of platelet activation. GBS-induced platelet aggregation was assayed by light transmission; platelet TLR2, CD62P and PAC-1 expression were determined by flow cytometry; AKT and AKT phosphorylation expression were determined by RT-PCR or western blot assay. In some experiments, platelets were pre-incubated with PI3-K specific inhibitors LY294002 or anti-TLR2 monoclonal antibody.3. Statistical analysis: Data are reported as the mean ± SD. Treatment groups were compared with the appropriate control (s), and statistical significance was examined using the two-tailed t-test. Differences were considered significant when P <0.05. All values were analyzed using SPSS version 17.0 software.Results1. Platelet activation and TLR2 protein expression: Platelet aggregation, surface expression of TLR2, CD62P and PAC-1 induced by GBS were increased significantly on the platelets upon activation with GBS 639. However incubated with anti-TLR2 monoclonal antibody, they all decreased.2. PI3-K/Akt signaling pathway: Real-time PCR showed that the PI3-K and Akt mRNA expression levels were increased significantly in the platelets stimulated with GBS 639. Western blot results showed that of Akt phosphorylation triggered by GBS was occurred as early as 15 min and increased gradually to reach a peak at 2 h post-infection and no significant changes were observed in total Akt protein expression during the infection. However, the expression of p-Akt, platelet aggregation and surface expression of CD62P and PAC-1 induced by GBS were significantly inhibited in the presence of a PI3-K inhibitor LY294002.3. The relationship between TLR2 and PI3-K/Akt signaling pathway in platelet activation: Platelet p-Akt expression levels induced by GBS were significantly decreased after the activity of platelet TLR2 was blocked by anti-TLR2 monoclonal antibody, and no significant changes in total Akt protein expression.Conclusions GBS induced platelet activation through the TLR2-PI3-K/Akt signaling pathway in human platelets. DisclosuresNo relevant conflicts of interest to declare.

A Novel PF4-Dependent Platelet Activation Assay Identifies Patients Likely to Have Heparin-Induced Thrombocytopenia/Thrombosis (HIT)

Antibodies (abs) specific for heparin/platelet factor 4 (H/PF4) complexes are a hallmark of heparin-induced thrombocytopenia and thrombosis (HIT) and are thought to play a role in predisposing patients to thrombocytopenia and thrombosis. A solid phase assay that uses H/PF4 complexes as targets for ab detection (PF4 ELISA) is almost invariably positive in patients with HIT. This test can be performed quickly and a negative result makes HIT very unlikely; however, many patients testing positive in this assay do not develop HIT. A second test, the serotonin release assay (SRA), considered the "gold standard" for HIT diagnosis, selectively detects HIT abs that activate platelets and are presumptively pathogenic. A positive SRA test correlates well with clinical HIT but the SRA is technically demanding and is routinely performed only by a few reference laboratories, precluding its use for early patient diagnosis and management. This can have adverse consequences since both over- and under-diagnosis of HIT can have serious medical and economic impact.We recently showed that platelet-activating HIT abs preferentially recognize PF4 bound to platelet glycosaminoglycans in the absence of heparin (Blood 2015; 125(1): 155-61). Based on this finding we developed a technically simple assay (PF4-dependent p-selectin expression assay [PEA]) for detection of platelet-activating HIT abs. In the PEA, target platelets are first "primed" for activation by being incubated with PF4 and are then exposed to patient serum. P-selectin expression (percent of maximum) is measured as an indicator of platelet activation (Thromb Haemost. 2015; 114(5) epub). Specificity of a positive test result is confirmed by inhibition with high dose heparin (HDH).To compare diagnostic performance of the PEA and the SRA, 91 sera from patients referred for HIT testing who had been assigned clinical scores for HIT ("4T scores") ranging from 0 to 8 (low to high likelihood of HIT, respectively) were tested in both assays. Samples from patients with Intermediate or High 4T scores (4-8) and PF4 ELISA OD values >1.0 were considered "HIT-positive " given that neither criterion by itself has a high positive predictive value for HIT. Intermediate to High 4T-scored patients with PF4 ELISA ODs <1.0 were considered "HIT-negative ", as were samples associated with low 4T scores, which are known to have a high negative predictive value for HIT.Receiver operating curve (ROC) analysis showed that the PEA had greater accuracy for identification of samples from HIT-positive patients than the SRA (AUC 0.93 vs. 0.82, respectively; p=0.01). When both sensitivity and specificity of an assay are important, one way to define a threshold for positivity is to determine the point on the ROC curve where the sum of sensitivity and specificity is maximized. This point in the PEA ROC curve corresponded to >24% p-selectin expression. For this analysis, a sample was considered PEA-positive if p-selectin expression was >24%, and inhibited >50% with HDH. Results are shown in Fig 1. The apparent superiority of the PEA over the SRA for identifying HIT-positive patients suggested that the PEA might be intrinsically more sensitive than the SRA for detecting platelet activating abs. This was confirmed by testing serial dilutions of 3 arbitrarily selected High-4T HIT abs against identical target platelets. A representative result is shown in Fig 2.The many attractive features of the PEA, especially its technical simplicity and its ability to identify patients judged to have a high likelihood of HIT suggest that its use can facilitate early diagnosis and improve management of this diagnostically challenging disorder.In Figures 1 and 2, the solid and dotted lines represent positive cut-offs of the SRA and PEA, respectively. [Display omitted] [Display omitted] [Display omitted] DisclosuresPadmanabhan:BloodCenter of Wisconsin: Patents & Royalties: A patent application has been filed based partly on these findings (Method of detecting platelet activating antibodies that cause heparin-induced thrombocytopenia/thrombosis; PCT/US14/62591). Jones:BLOODCENTER OF WISCONSIN: Patents & Royalties: A patent application has been filed based partly on these findings (Method of detecting platelet activating antibodies that cause heparin-induced thrombocytopenia/thrombosis; PCT/US14/62591). Bougie:BLOODCENTER OF WISCONSIN: Patents & Royalties: A patent application has been filed based partly on these findings (Method of detecting platelet activating antibodies that cause heparin-induced thrombocytopenia/thrombosis; PCT/US14/62591). Aster:BLOODCENTER OF WISCONSIN: Patents & Royalties: A patent application has been filed based partly on these findings (Method of detecting platelet activating antibodies that cause heparin-induced thrombocytopenia/thrombosis; PCT/US14/62591).

Surface Ifitms on Megakaryocytes and Platelets Regulate Fibrinogen Endocytosis Under Inflammatory Conditions

BackgroundIFITM proteins (IFITM-1, -2, and -3) mediate cellular resistance to influenza, dengue, and other viruses. IFITM expression on human platelets has not been previously recognized. Our laboratory recently demonstrated that IFITMs are robustly expressed by human platelets and megakaryocytes after stimulation by pathogens and inflammatory mediators and restrict viral infection. IFITMs, which are interferon inducible, also mediate clathrin localization and associated protein endocytosis. Nevertheless, whether IFITMs regulate protein endocytosis by platelets and megakaryocytes remains unknown.AimsWe investigated IFITM expression on murine megakaryocytes and platelets and determined whether IFITMs regulate fibrinogen endocytosis under basal and inflammatory conditions.MethodsWe examined the expression of IFITMs and clathrin in bone-marrow derived murine megakaryocytes and platelets under basal conditions and following interferon-beta (IFN-β) stimulation. To determine whether upregulation of IFITM causes increased fibrinogen endocytosis, megakaryocytes were stimulated ex vivo with IFN-β and treated with labeled fibrinogen. Endocytosis of labeled fibrinogen was then measured by immunocytochemistry and flow cytometry. To determine whether this response also occurred in vivo, C57Bl/6 mice were injected intraperitoneally (IP) with 50,000 units of IFN-β over four days. On the fourth day, 100 μg of labeled fibrinogen was injected into the tail vein and the amount of endocytosed, labeled fibrinogen in platelets was determined the next day via flow cytometry. Parallel experiments were performed in age and gender matched IFITM-/- mice.ResultsBone-marrow derived murine megakaryocytes and platelets basally express IFITMs. Upon IFN-β stimulation, IFITM and clathrin expression significantly increased (p<0.05). Fibrinogen endocytosis by murine megakaryocytes occurred under resting conditions and appeared to be punctate and granular in nature. Upon IFN-b stimulation, fibrinogen endocytosis in megakaryocytes significantly increased compared to unstimulated conditions (p<0.004). The increase in endocytosis appeared independent of changes in αIIbβ3 expression as IFN-β stimulation did not change αIIbβ3 surface protein. Fibrinogen endocytosis after IFN-β stimulation did not increase in megakaryocytes from IFITM-/- mice, suggesting that IFITMs regulate fibrinogen uptake under these conditions. We next determined if fibrinogen endocytosis occurred in platelets isolated from IFITM-/- mice. Platelet counts and activation indices (assessed by JonA staining) were similar in C57Bl/6 mice (WT) and IFITM-/- mice. Nevertheless, the injection of IFN-β IP results in significant increases in fibrinogen endocytosis by platelets in vivo in WT but not IFITM-/- mice (p<0.02).Summary/ConclusionsThese findings suggest IFITMs, in addition to their anti-viral roles, mediate fibrinogen endocytosis. Further, in settings where inflammatory stimuli such as interferons are increased, enhanced IFITM expression may promote upregulation of fibrinogen endocytosis by platelets and megakaryocytes. DisclosuresNo relevant conflicts of interest to declare.

The platelet-to-lymphocyte ratio reflects the severity of obstructive sleep apnea syndrome and concurrent hypertension

BackgroundChronic intermittent hypoxia, platelet activation and inflammation all play roles in the pathogenesis of obstructive sleep apnea syndrome (OSAS), which may increase the risk of cardiovascular disease (CVD). The aim of this study was to evaluate the relationship of the platelet-to-lymphocyte ratio (PLR) as a new biomarker showing systemic inflammation and platelet distribution width (PDW) as an indicator of platelet activation to the severity of OSAS.MethodsA total of 290 patients suspected with OSAS who underwent a full night of polysomnography were included. The patients were placed into 4 separate groups according to their apnea-hypopnea index (AHI) scores; the control group (AHI <5), mild OSAS group (AHI 5–15), moderate OSAS group (AHI 16–30), and severe OSAS group (AHI >30). CVD risk was defined by the presence of hypertension, diabetes mellitus, current smoking, and dyslipidemia.ResultsHigher AHI groups were significantly correlated with increasing age, body mass index, systolic blood pressure and male sex. PLR and PDW were also significantly associated with AHI (r = 0.417 for PLR and r = 0.227 for PDW, all p-values < 0.001) and the Epworth sleepiness scale (r = 0.160 for PLR and r = 0.189 for PDW, all p-values <0.05). Multivariate regression analysis revealed that AHI ≥9.2 (adjusted odds ratios [OR] 5.03, 95 % confidential interval (CI) = 1.67-15.2, p = 0.004) and PLR ≥159 (adjusted OR 2.81, 95 % CI = 1.34-5.91, p = 0.006) were independently associated with the presence of hypertension.ConclusionPLR and PDW are associated with OSAS severity. PLR may also be useful as a systemic biomarker for the concurrent hypertension in OSAS patients.

Assessment of Mean Platelet Volume in Patients with Resistant Hypertension, Controlled Hypertension and Normotensives.

Patients with resistant hypertension are at increased risk for cardiovascular events. Mean platelet volume (MPV) is an accepted biomarker of platelet activation and considered as a risk factor for cardiovascular disease. The aim of this study was to determine whether MPV levels are higher in resistant hypertensive (RHTN) patients than in controlled hypertensive (CHTN) patients and healthy normotensive controls. 279 consecutive patients were included in this study. Patients were divided into three groups: Resistant hypertension patient group [n=78; mean age 56.8±9.8; 42 males (53.8%)]; controlled hypertension patient group [n=121; mean age 54.1±9.6; 49 males (40.5%)]; and normotensive control group [n=80; mean age 49.8±8.5; 34 males (42.5%)]. Physical examination, laboratory work-up, and 24-hour ambulatory blood pressure measurement (ABPM) were performed in all participants. The mean platelet volume levels were significantly higher in RHTN group than in the CHTN and normotensive groups (p<0.001). In correlation analysis office systolic and diastolic blood pressure was positively correlated with MPV. Our study demonstrated that MPV, as an important indicator of platelet activation, was statistically higher in RHTN patients than in CHTN and in normotensive subjects. Elevated MPV levels may help to determine a high risk group for atherosclerosis in RHTN patients.

Increased mean platelet volume in patients with panic disorder.

ObjectiveThe relationship between platelet activation and psychiatric disorders has been shown in previous work. Mean platelet volume (MPV) is a measure of platelet size and a good indicator of platelet activity, which increases in cardiovascular diseases (CVDs). It is known that anxiety is a considerable factor in the etiology of mortality in CVDs. The aim of the present study was to investigate any probable difference in the MPV of patients with panic disorder (PD).MethodsSixty-one drug-free patients, aged 18–65 years and diagnosed with PD according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, were included in the study, along with 63 healthy age- and sex-matched volunteers. The body mass index (BMI) was calculated and MPV measured for each subject.ResultsThe MPV was found to be higher in the PD group compared to the control group (P=0.004). There were no significant differences between the two groups in terms of platelet count or BMI.ConclusionAlterations in platelet activity may be a reflection of abnormal 5-hydroxytryptamine (5-HT) 1A receptor function in the central nervous system of subjects with a diagnosis of PD. These findings may elucidate the relationship between CVDs and PD. The findings of the present study suggest that MPV is increased in PD patients.

Accumulation of CD62P during storage of apheresis platelet concentrates and the role of CD62P in transfusion-related acute lung injury.

Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-associated morbidity and mortality. Activated platelets have important roles in TRALI and CD62P was identified to be an important indicator of platelet activation. However, the precise roles of CD62P in TRALI have remained elusive. The present study assessed CD62P accumulation during storage of apheresis platelet concentrates (A‑Plts) and established a mouse model of TRALI to further investigate the roles of CD62P in TRALI. The results showed that the CD62P concentration in A‑Plts was increased with the storage time. Mice were treated with monoclonal major histocompatibility complex (MHC)‑1 antibody to induce TRALI. The murine model of TRALI was successfully established as evidenced by pulmonary oedema, accompanied by decreased clearance of bronchoalveolar lavage fluid (BALF), increased pulmonary and systemic inflammation, elevated lung myeloperoxidase (MPO) activity as well as increased pulmonary and systemic coagulation in the TRALI group compared with those in the control group. To further determine the role of CD62P in TRALI, mice were treated with anti‑CD62P antibody to knockdown CD62P in vivo. It was found that pulmonary oedema, BALF clearance, pulmonary and systemic inflammation, MPO activity as well as pulmonary and systemic coagulation were decreased in the TRALI + anti‑CD62P antibody group compared with those in the TRALI + isotype antibody group. The present study supported the notion that CD62P is involved in mediating TRALI and may provide an important molecular basis for enhancing the clinical safety and effectiveness of platelet transfusion.

Usefulness of mean platelet volume for predicting stroke risk in paroxysmal atrial fibrillation patients.

Atrial fibrillation is the most common sustained arrhythmia in clinical practice. It is important to specify patients with a high risk of thromboembolus due to elevated procoagulant and prothrombotic state. The aim of this study is to assess the relation of stroke/transient ischaemic attack (TIA) with mean platelet volume (MPV), which is an indicator of platelet activation in patients with paroxysmal atrial fibrillation (PAF). Patients with PAF were enrolled in this study during years of 2012-2014. Patients were divided into two groups according to the presence or absence of stroke/TIA. Demographic data were registered and CHA2DS2VASc scores of patients were calculated. It was investigated whether there was a difference among groups regarding MPV levels. Ninety patients, 31 of whom had history of stroke/TIA (symptomatic group), were enrolled to study. CHA2DS2VASc score of symptomatic group was 4.77 ± 1.26, while CHA2DS2VASc score of asymptomatic group was 2.63 ± 1.41. Nevertheless, there was not any difference regarding CHA2DS2VASc score among two groups when 2 points due to stroke/TIA were subtracted in symptomatic patients. MPV was detected higher in symptomatic patients than asymptomatic patients (11.1 ± 1.3 vs. 9.1 ± 1.0 fL, P < 0.001, respectively). A value of 9.85 for the MPV ascertained with receiver operating characteristic (ROC) curve analysis to predict stroke/TIA was found to have a sensitivity of 87% and specificity of 78%. Elevated MPV levels were ascertained to be related with stroke/TIA in patients with PAF. Assessment of MPV apart from CHA2DS2VASc score in patients with PAF might be subsidiary to specify patients with an enhanced risk of stroke/TIA.