Aspirin-sensitive Patients Research Articles

Cytokine Expression Before and After Aspirin Desensitization Therapy in Aspirin-Exacerbated Respiratory Disease

Aspirin exacerbated respiratory disease (AERD) is induced by acetylsalicylic acid (ASA) and/or nonsteroidal antiinflammatory drugs (NSAIDs). Effects of desensitization on many mediators have been examined previously, but few studies addressed the influence of desensitization on T lymphocytes and T lymphocyte-derived cytokines. This study was performed to examine peripheral blood lymphocyte (PBL) cytokine expression in aspirin-sensitive patients who have asthma before and after aspirin desensitization. In this study, the release of interleukin-2 (IL-2), interleukin-4 (IL-4), and interferon-gamma (IFN-γ) by CD4+ T lymphocytes prior to aspirin desensitization were also measured at intracellular levels, and expression of these cytokines after 1 month aspirin desensitization was evaluated. Twelve patients with AERD were included in the study. Two different control groups were formed, one consisted of 15 healthy people and second 12 aspirin tolerant asthmatic (ATA) patients using aspirin. A blood sample was collected prior to desensitization, and the tests were repeated by taking a second blood sample 1 month after the 4-day desensitization treatment. The proportion of lymphocytes secreting IFN-γ in the study group was 15.61 ± 4.40 % before desensitization and 15.08 ± 5.89 % after desensitization. The rate of IFN-γ secreting CD4+ T lymphocytes was 20.51 ± 4.41 % in the normal control group and 16.07 ± 5.7 % in the ATA group (p = 0.021). The ratio of CD4+ T lymphocyte secreting IFN-γ was reduced in patients with AERD before desensitization compared to normal control group (p = 0.040). The levels of IL-2, IL-4, and the subsets of lymphocyte were not different before and after desensitization compared to control groups.

A Comparison of VerifyNow® with PlateletMapping® -Detected Aspirin Resistance and Correlation with Urinary Thromboxane

Aspirin-resistant platelet activation in whole blood is attributable to a transcellular pathway not detected by isolated platelet aggregometry. Aspirin resistance as defined by urinary thromboxane levels is associated with increased risk for myocardial infarction or cardiac death. Whole blood point-of-care assays may also detect aspirin resistance. We compared PlateletMapping® with VerifyNow® for detecting aspirin resistance in 200 patients undergoing invasive cardiac procedures. This included 10 patients not receiving aspirin therapy for comparison. The assay results were correlated with urinary 11-dehydro-thromboxane B2 collected 2 to 8 hours after the procedure. PlateletMapping detected aspirin resistance in 32% of patients. VerifyNow detected aspirin resistance in 6% of patients. A patient's compliance with aspirin therapy was confirmed by a <20% aggregation response to arachidonic acid by light transmission aggregometry. Aspirin-resistant patients as determined by PlateletMapping had significantly (P<0.001) higher urinary 11-dehydro-thromboxane B2 levels than aspirin-sensitive patients but significantly (P=0.001) lower levels than patients not receiving aspirin therapy. There was no significant difference in urinary 11-dehydro-thromboxane B2 for aspirin-resistant compared with aspirin-sensitive patients as determined by VerifyNow, but the confidence intervals were wide. There was no significant correlation of resistance as defined by PlateletMapping with aspirin dose. However, there was significant increased aspirin sensitivity with clopidogrel (0.0006) or statin (0.004) cotherapies. There also was a significant correlation of smoking with aspirin resistance. These results indicate that PlateletMapping could be a useful point-of-care assay to identify aspirin-resistant patients for better perioperative risk stratification and management.

Periostin may play a protective role in the development of eosinophilic chronic rhinosinusitis with nasal polyps in a mouse model

Several genes have been reported to be upregulated in human nasal polyps in previous genetic analyses. Among these genes, periostin is known to be overexpressed in nasal polyps obtained from aspirin-sensitive patients. Using periostin-null mice, we investigated the role of periostin in a murine model of eosinophilic rhinosinusitis with nasal polyps. Animal study. Eosinophilic rhinosinusitis was induced in both periostin-null and wild-type mice according to previously established protocols. In brief, ovalbumin (OVA) was used for sensitization and prolonged intranasal stimulation. Staphylococcus aureus enterotoxin B was applied intranasally to develop polyplike lesions. To examine the inflammation and mucosal lesions, hematoxylin and eosin, Sirius red, and Giemsa staining were performed. There was no definite difference in the maximal mucosal thickness between periostin-null and wild-type mice. In contrast, some parameters of inflammation, including the number of polyplike lesions and mast cells, were aggravated in the periostin-null mice compared to wild type. Eosinophilic infiltration was aggravated in the OVA-stimulated periostin-null mice, compared to OVA-stimulated wild-type mice, whereas there was no apparent difference between wild-type and periostin-null mice challenged with additional S aureus enterotoxin B. The loss of periostin appears to enhance polyplike lesion formation and mast cell infiltration in a mouse model of eosinophilic rhinosinusitis with nasal polyps.

Renal function and aspirin resistance in patients with coronary artery disease

Aspirin resistance and chronic renal failure are both potentially important clinical issues in coronary artery disease. To test the hypothesis of a relationship between the two, we recruited 169 stable outpatients with proven coronary artery disease (myocardial infarction, coronary artery bypass grafting, intra-coronary stents) taking 75mg aspirin daily. Blood was taken for light transmission aggregometry to agonists arachidonic acid (0.5mg/mL) and adenosine diphosphate (10μmol/L), for platelet marker soluble P selectin (enzyme linked immunosorbent assay), resting and stimulated expression of CD62P (flow cytometry) and for renal function (estimated glomerular filtration rate). The estimated glomerular filtration rate was lower when aspirin resistance was defined by response to arachidonic acid after 3, 5 and 7minutes (approximately 30% of patients) (p<0.021), and when defined by response to adenosine diphosphate after 3minutes (approximately 17% of patients)(p=0.015) compared to those who were sensitive to aspirin. Mean [standard deviation] soluble P selectin levels were 57 [23] ng/mL in 49 patients with aspirin resistance, and 50 [15] ng/mL in the 119 aspirin sensitive patients (p=0.02). Estimated glomerular filtration rate correlated inversely with platelet CD62P expression at rest (r=−0.22, p=0.004), and when stimulated by arachidonic acid (r=−0.21, p=0.007) and by adenosine diphosphate (r=−0.17, p=0.023). Aspirin resistance was more than twice as prevalent in those with the greatest renal disease (50% of patients) compared to those with the best renal function (21.4%). Our data point to a weak relationship between worsening glomerular filtration rate and aspirin resistance. Nevertheless, we suspect that failure of patients to be fully responsive to aspirin may be important in the pathophysiology of thrombosis in renal dysfunction.

Sinonasal outcome under aspirin desensitization following functional endoscopic sinus surgery in patients with aspirin triad

Recalcitrant forms of recurrent nasal polyposis are problematic for patients as for rhinosurgeons. In aspirin-sensitive patients, aspirin desensitization is supposed to prevent recurrence by targeting the metabolism of arachidonic acid. Aspirin-sensitive patients (n = 65) following aspirin desensitization after functional endoscopic sinus surgery (FESS) for recurrent nasal polyposis under daily intake of 500-mg aspirin were compared to a post-FESS group (n = 81) of aspirin-sensitive individuals using exclusively topical mometasone. Quality of life (QoL) scores including sinonasal, pulmonal and general QoL items as well as endoscopic endonasal examination findings were evaluated during the postoperative follow-up period. After a follow-up period of minimum 18 months, a significant improvement in nasal obstruction, rhinorrhea, post nasal drip, sense of smell, facial pain, sleep quality and further general QoL items in desensitized patients was found compared to aspirin-sensitive controls. Improvement in sinonasal symptoms was evident, whereas the severity of asthmatic symptoms showed no significant changes. Although the pathophysiology of aspirin sensitivity is still not fully understood and the therapy is not sufficiently investigated, aspirin desensitization seems to have a positive effect on QoL scores concerning sinonasal symptoms and should be regarded as a possible postoperative treatment modality for recurrent nasal polyposis in aspirin-sensitive individuals.

The prevalence, risk factors and prognosis of aspirin resistance in elderly male patients with cardiovascular disease

Aim:Aspirin resistance is recognized in different population. However, the prevalence and clinical events of aspirin resistance in elderly male patients with cardiovascular disease (CVD) have not been reported. Methods: We enrolled 304 elderly male patients with CVD receiving daily aspirin therapy (≥ 75 mg) more than 1 month. Platelet aggregation was measured by light transmission aggregometry (LTA) and thrombelastography platelet mapping assay (TEG). The median follow-up time was 1.8 years. The primary outcome was the composite of death, myocardial infarction, unstable angina, stroke and transient ischemic attack. Results: By LTA, 25 (8.2%) of elderly patients were aspirin resistant and 106 (34.9%) patients were semiresponders. According to TEG, 62 patients (20.4%) were found to be resistant to aspirin therapy. Of the 62 patients with aspirin resistance by TEG, 21 patients were aspirin resistant by LTA. Twenty-two of the 106 semiresponders by LTA were aspirin resistant by TEG. Patients with aspirin resistance or aspirin semiresponders were at increased risk of the composite outcome compared with aspirin-sensitive patients by LTA (18.3% vs 9.8%, Hazard ratio (HR) = 1.864, 95% confidence interval (CI): 1.046–3.324 p = 0.039). However, aspirin resistance was not associated with an increased risk of clinical vascular events compared to aspirin-sensitive patients by TEG (17.7% vs 10.9%, p = 0.452). In addition, Cox proportional hazard regression modeling demonstrated that aspirin resistance or semiresponders (HR = 3.050, 95% CI: 1.464–6.354, p = 0.003) and diabetes (HR = 2.055, 95% CI: 1.060–3.981, p = 0.033) were associated with major adverse long-term outcomes.Conclusions: Aspirin resistance or semiresponders, defined by LTA, are associated with an increased risk of adverse clinical events in elderly male patients with CVD.

Exhaled Eicosanoids following Bronchial Aspirin Challenge in Asthma Patients with and without Aspirin Hypersensitivity: The Pilot Study

Background. Special regulatory role of eicosanoids has been postulated in aspirin-induced asthma. Objective. To investigate effects of aspirin on exhaled breath condensate (EBC) levels of eicosanoids in patients with asthma. Methods. We determined EBC eicosanoid concentrations using gas chromatography/mass spectrometry (GC-MS) and high-performance liquid chromatography/mass spectrometry (HPLC-MS2) or both. Determinations were performed at baseline and following bronchial aspirin challenge, in two well-defined phenotypes of asthma: aspirin-sensitive and aspirin-tolerant patients. Results. Aspirin precipitated bronchial reactions in all aspirin-sensitive, but in none of aspirin-tolerant patients (ATAs). At baseline, eicosanoids profile did not differ between both asthma groups except for lipoxygenation products: 5- and 15-hydroxyeicosatetraenoic acid (5-, 15-HETE) which were higher in aspirin-induced asthma (AIA) than inaspirin-tolerant subjects. Following aspirin challenge the total levels of cysteinyl-leukotrienes (cys-LTs) remained unchanged in both groups. The dose of aspirin had an effect on magnitude of the response of the exhaled cys-LTs and prostanoids levels only in AIA subjects. Conclusion. The high baseline eicosanoid profiling of lipoxygenation products 5- and 15-HETE in EBC makes it possible to detect alterations in aspirin-sensitive asthma. Cysteinyl-leukotrienes, and eoxins levels in EBC after bronchial aspirin administration in stable asthma patients cannot be used as a reliable diagnostic index for aspirin hypersensitivity.

Coagulation system reaction to blood loss volume as a result of coronary artery bypass surgery in aspirin-resistant patients with coronary heart disease and arterial hypertension

Objective. To assess the coagulation system reaction and blood loss volume depending on aspirin resistance in hypertensive patients with coronary heart disease who underwent bypass surgery. Design and methods. A total of 66 patients with arterial hypertension and coronary heart disease (angina pectoris of III-IV functional class according to Canadian classification) who underwent myocardial revascularization using extracorporeal circulation were examined. All patients were divided into two groups depending on aspirin resistance phenomenon. 22 aspirin-resistant patients formed the first group, the other group consisted of 44 aspirin-sensitive patients. The patients were 49 to 68 year old, and there were 27 women and 39 men. During intraoperative and postoperative periods blood loss was measured in all subjects. Results. We showed that 22 out of 66 patients were aspirin-resistant. No relationship between blood loss volume during intraoperative and postoperative periods and aspirin resistance was observed. All hemostatic system indices regardless of aspirin resistance phenomenon changed equally in both groups.

Single nucleotide polymorphisms of HO-1 and COX-1 are associated with complete aspirin resistance defined by light transmittance aggregation in the Elderly

BackgroundAspirin remains the cornerstone of treatment for atherothrombotic diseases, but various factors associated with inflammation, platelets, the vascular system, coagulation, and metabolism may result in aspirin resistance (AR). This study...

Variations in expression of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 in nasal mucosa of aspirin-sensitive versus aspirin-tolerant patients with nasal polyposis

Matrix metalloproteinases (MMPs) are key enzymes responsible for extracellular matrix degradation contributing to the progressive histological changes seen in lower airway disease, including asthma. MMP-9 and TIMP-1 have also shown some role in the pathogenesis of chronic rhinosinusitis (CRS) and nasal polyposis (NP). We aim to determine variability in expression of MMP-9 and its inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), in sinus tissue from distinct patient populations presenting with nasal polyposis. The expression of MMP-9 and TIMP-1 was investigated in nasal polyp tissue from 6 aspirin-sensitive (AS) and 6 aspirin-tolerant (AT) patients undergoing endoscopic sinus surgery for chronic rhinosinusitis with nasal polyposis (CRSwNP). Sinus mucosa from 6 patients with chronic rhinosinusitis without nasal polyposis (CRSsNP) was used as control. The MMP-9 and TIMP-1 expression was measured using immunofluorescence technique and graded using manual and computerized methods. Expression of TIMP-1 was significantly reduced in the AS group when compared with both the AT and CRSsNP (control) groups (P < .001). The MMP-9/TIMP-1 ratio was significantly increased in the AS group when compared with other patient groups (P < .001). The MMP- 9 expression was similar between study and control groups. These results support the importance of MMP-9 and TIMP-1 expression in nasal polyp formation. The decreased expression of TIMP-1 in AS patients may promote the effects of MMP-9 expression and thus contribute to tissue remodeling and inflammatory changes. This finding may lead to further understanding of disease severity and resistance to treatment in this group of patients, as well as the pathogenesis of nasal polyps.

Aspirin resistance in patients with acute ischemic stroke

Aspirin is used in ischemic stroke therapy. However, some patients are not responsive to the antithrombotic action of aspirin. The aim of this study was to assess the prevalence of aspirin resistance in stroke patients and its association with mortality. One-hundred and six patients (mean age 64.9 ± 14.6 years, 53 male) with acute ischemic stroke were consecutively recruited. All subjects were taking aspirin regularly. Aspirin responsiveness was determined by Ultegra Rapid Platelet Function Assay-ASA (VerifyNow Aspirin). Aspirin resistance was defined as aspirin reaction unit (ARU) ≥ 550. Aspirin resistance was detected in 35 patients. There were not any significant differences in age, gender and comorbidities between aspirin-resistant and aspirin-sensitive patients. The mean National Institute of Health Stroke Scale (NIHSS) scores of the aspirin-resistant and aspirin-sensitive patients were 15 ± 3 and 12 ± 5, respectively (p = 0.006). Twenty-seven patients had a history of prior ischemic stroke and eight of them had aspirin resistance. Eleven patients died in-hospital and a total of 43 patients died during 2 years. Both the in-hospital and 2-year mortality rates were significantly higher in patients with aspirin resistance (20 vs. 5.6%, p = 0.038 and 60.0 vs. 31.0%, p = 0.004, respectively). Regression analysis revealed aspirin resistance [odds ratio (OR) 3.097, 95% confidence interval (CI) 1.070-8.959, p = 0.037] as an independent predictor of 2-year mortality, as well as age (OR 1.051, 95% CI 1.003-1.102, p = 0.038) and NIHSS scores (OR 1.208, 95% CI 1.016-1.437, p = 0.033). Aspirin resistance is not uncommon in patients with acute ischemic stroke and is associated with short and long term mortality in these patients.

Diagnosis and management of drug hypersensitivity reactions

The present article addresses the advances in the diagnosis and management of drug hypersensitivity reactions that were discussed in the 4th Drug Hypersensitivity Meeting held in Rome in April 2010. Such reactions can be classified as immediate or nonimmediate according to the time interval between the last drug administration and onset. Immediate reactions occur within 1 hour, and nonimmediate reactions occur after more than 1 hour. Clinical and immunologic studies suggest that type-I (IgE-mediated) and type-IV (T cell-mediated) pathogenic mechanisms are involved in most immediate and nonimmediate reactions, respectively. In diagnosis prick, patch, and intradermal tests are the most readily available tools. Determination of specific IgE levels is still the most common in vitro method for diagnosing immediate reactions. New diagnostic tools, such as the basophil activation test, the lymphocyte activation test, and enzyme-linked immunospot assays for analysis of the frequency of antigen-specific, cytokine-producing cells, have been developed for evaluating either immediate or nonimmediate reactions. The sensitivity of allergologic tests is not 100%; therefore in selected cases provocation tests are necessary. In the diagnosis of nonallergic hypersensitivity reactions to nonsteroidal anti-inflammatory drugs, the provocation test with the suspected drug still represents the "gold standard." However, there was no consensus regarding the use of this test in subjects with histories of hypersensitivity reactions to 1 (single reactors) or more (multiple reactors) nonsteroidal anti-inflammatory drugs. With regard to management, desensitization allows patients to be treated with irreplaceable chemotherapy agents, such as taxanes, platinum salts, and mAbs, to which they have presented hypersensitivity reactions. Desensitization also permits the use of aspirin in aspirin-sensitive patients undergoing revascularization and in subjects with aspirin-exacerbated respiratory disease.

Determination of the Prevalence of Aspirin and Clopidogrel Resistances in Patients with Coronary Artery Disease by using Various Platelet-function Tests

Dual therapy with aspirin and clopidogrel has emerged as the gold standard therapy for patients treated with drug-eluting stents (DES). However, there is variability in patients' responses to this antiplatelet therapy, and some patients continue to show ischemic recurrences after therapy. The purpose of the study was to compare the simultaneously obtained results of various platelet-function tests for assessing the prevalence of antiplatelet resistance in coronary artery disease patients undergoing DES therapy. A total of 66 patients were administered a loading dose of aspirin, clopidogrel, and cilostazol at least 12 hr before stenting. The results of VerifyNow (Accumetrics, USA), multiplate analyzer (Dynabyte Medical, Germany), and vasodilator-stimulated phosphoprotein/P2Y12 (Biocytex, France) assays were compared with those of light transmission aggregometry (LTA) analysis. The P2Y12 reaction units and P2Y12% inhibition values obtained using the VerifyNow assay showed strong correlation (r) with the results of the LTA analysis. All tests results showed low concordance in defining the antiplatelet resistance in patients, and the degrees of agreement were as follows: 0 for aspirin reaction units; 0.25, P2Y12% inhibition; 0, aspirin-sensitive patients' identification test; 0.21, ADPtest; and 0.14, platelet reactivity index, expressed as the κ statistics. The prevalence of aspirin and clopidogrel resistances in patients resulted in remarkable variations, from 0% to 22.7% and from 9.1% to 48.5%, respectively. The clinical usefulness of the different assays for the correct classification of patients in terms of antiplatelet resistance remains unclear. Further studies are required to determine the best method for correlating the occurrences of adverse ischemic events.

Different expression of proteins in platelets from aspirin-resistant and aspirin-sensitive patients

The aim of the present study was to analyse differences in the protein expression profile between platelets from aspirin (ASA)-resistant patients and ASA-sensitive patients. We analysed platelets from 51 clinically stable coronary ischaemic patients taking ASA (100 mg/day) divided into ASA-resistant (n=25) and ASA-sensitive (n=26) based on a platelet functionality test (PFA-100). Proteins associated with cytoskeleton, energetic metabolism, oxidative stress, inflammation and cell survival were analysed by two-dimensional electrophoresis and mass spectrometry. The expression of two gelsolin precursor isotypes and one F-acting capping protein isotype was decreased in ASA-resistant platelets (p<0.05). The expression of glyceraldehyde 3-phosphate dehydrogenase was increased in the ASA-resistant platelets (1751.1 + or - 220.6 vs. 4273.3 + or - 971.7, 95% confidence interval [CI] 1815.11 to 4061.2, p=0.001). It was accompanied by a reduced expression and activity of 1,6-bisphosphate aldolase in platelets without changes in the content of pyruvate. A reduced expression of gluthathione-S-transferase and the protein disulfide isomerase isotype 1 was found in ASA-resistant platelets. The protein expression of the chloride intracellular channel isotype 1 was increased in ASA-resistant platelets (21.3 + or - 3.8 vs. 48.8 + or - 6.0, CI 29.5 to 45.95, p=0.03) while the expression of two HSP60 and two HSP71 isotypes was decreased. No changes were observed in proteins associated with inflammation. In conclusion, ASA-resistant and ASA-sensitive platelets are different in terms of the level of expression of proteins associated with mechanisms such as energetic metabolism, cytoskeleton, oxidative stress and cell survival which may be associated with their different ability to respond to ASA.

Impact of genetic polymorphisms on platelet function and aspirin resistance

Genetic polymorphisms may affect platelets' responses to the antiplatelet therapy. Our aim was to determine the role of genetic polymorphisms on aspirin resistance in patients with coronary heart disease (CHD). A total of 126 consecutive patients (35-85 years old, 32% women) with chronic stable CHD was enrolled in the study. Platelet function assays were realized by the platelet function analyzer (PFA)-100 with collagen and epinephrine (Col/Epi) and collagen and adenosine diphosphate (Col/ADP) cartridges. Aspirin resistance was defined as having a closure time of less than 186 s with Col/Epi cartridges despite regular aspirin therapy. Factor V, prothrombin, factor XIII, beta-fibrinogen, plasminogen activator inhibitor I (PAI-1), glycoprotein IIIa, methylene tetrahydrofolate reductase, ACE and ApoB gene polymorphisms were determined by three consecutive steps: isolation and amplification of DNA and reverse hybridization. We determined that 30 patients (23.8%) had aspirin resistance by the PFA-100. Mean closure time measured with the Col/ADP cartridges was 74 +/- 12 s (51-104 s). Ten of the 30 patients with aspirin resistance were women (33.3%). Genetic polymorphisms were determined in 30 aspirin-resistant and 17 aspirin-sensitive patients. No statistically significant relationship was determined between aspirin resistance and the genetic panel. In our study we did not determine a significant relationship between the aspirin resistance and factor V, prothrombin, factor XIII, beta-fibrinogen, PAI-1, glycoprotein IIIa, methylene tetrahydrofolate reductase, ACE and ApoB gene polymorphisms.

Post interventional cardiology urinary thromboxane correlates with PlateletMapping® detected aspirin resistance

Introduction We have previously defined aspirin resistance detected by TEG PlateletMapping using arachidonic acid (AA). This aspirin resistance is observed as platelet activation (> 20%) by AA in whole blood, even though the isolated platelets are inhibited by aspirin. This platelet activation in whole blood is due to a transcellular pathway mediated by platelets and leukocytes. Methods To determine if this PlateletMapping assay of aspirin resistance on pre-procedure blood samples correlated with an in vivo response we assayed the first voided urine samples collected 2-8 hours post interventional cardiology procedures for 11-dehydro thromboxane B2. Results and Conclusions We detected 27 aspirin resistant patients out of a total of 81 (33%), in agreement with our previous study. All of these patients were on aspirin therapy, confirmed by a < 20% aggregation response to AA by light transmission platelet aggregometry using isolated platelet rich plasma. Aspirin resistant patients urine samples (14 out of a total of 60 patients analyzed) contained significantly (P = 0.008) higher 11-dehydro thromboxane B2 levels than the other 46 aspirin sensitive patients urine samples. Since our previous study implicated 12- and 15-lipoxygenases in this pathway, we also assayed for polymorphisms to determine any correlation with aspirin resistance. A correlation was found in a polymorphism affecting the lipoxygenase domain of platelet 12-lipoxygenase. This result indicates that aspirin resistance detected in whole blood by the TEG PlateletMapping assay correlates with a physiological consequence in terms of thromboxane formation. This is the first report of such a correlation.

Variability in aggregometry response before and after initiation of clopidogrel therapy

Background: Evaluation of clopidogrel therapy by in vitro methods has limitations which may be of clinical importance. We wanted to explore the variability in aggregometry response in aspirin sensitive patients before and after initiation of clopidogrel therapy. Methods: ADP 9.37 μM, AA 1.2mM and TRAP 25mM stimulated light transmissions aggregometry (LTA) were performed twice before (Exams 1 and 2; 3 weeks apart)-and within one year after-initiation of clopidogrel therapy (Exam 3) in 79 patients treated with PCI. Repeated ADP aggregometry was also performed in 16 healthy volunteers in order to estimate LTA measurement error. Result:. Inter-individual differences in ADP aggregation e.g. at Exam 1 were substantial (range 17–77%, SD 15.8%). Intra-individual changes between Exams 1 and 2 were significant (−27 to +36%, SD 14.6%, p<0.05). Inter-individual differences at Exam 3 (on clopidogrel treatment) were larger than expected from Exams 1 and 2 (p<0.01). AA aggregation was the same before and during clopidogrel treatment. In controls, inter-individual differences were smaller at ADP 10 than at ADP 5μM. Conclusions. Inter-individual differences in ADP aggregation were significant both before and during clopidogrel therapy, and there were significant intra-individual variations over time. Therefore, prediction of aggregometry response before or during clopidogrel therapy based on single tests may be unreliable. Inter-individual differences in healthy controls are smaller at high concentrations of ADP, and comparisons of aggregometry response should be performed with caution unless ADP concentrations are standardized.

Resistance to low-dose aspirin therapy among patients with acute coronary syndrome in relation to associated risk factors

A substantial proportion of patients have recurrence of vascular events despite daily intake of low-dose aspirin therapy. Therefore, different patients may require different aspirin dosages to achieve complete inhibition of platelet function. The aim of this work was to measure the response to low-dose aspirin therapy (150 mg/day) among patients with unstable angina or non-ST-segment elevation myocardial infarction and to find out whether titrating aspirin dosage to 300 mg/day, would provide a better therapeutic response in the resistant cases. Moreover, we also aimed to study any association between aspirin non-responsiveness and atherothrombotic risk factors. The antiplatelet effect of 150 mg/day aspirin was studied prospectively in 50 consecutive patients with unstable angina or non-ST-segment elevation myocardial infarction. Platelet aggregation was measured using optical platelet aggregometry and serum thromboxane B(2) level. Aspirin resistance was defined as collagen (1 μg/mL) and adenosine diphosphate (ADP) (5 μmol/L)-induced platelet aggregation of ≥ 40% when compared with control values. Twenty healthy age- and sex-matched individuals were taken as a control group. All patients were subjected to complete medical history (risk factors, medications), thorough clinical examination, ECG, coronary angiography and laboratory investigations including: complete haemogram, coagulation, kidney, liver and lipid profiles, fasting blood glucose and glycated haemoglobin (HbA(1C) ). Eleven of 50 patients (22%) were found to be aspirin resistant. A highly significant difference was found between the mean values of ADP, collagen-induced platelet aggregation percentage and thromboxane B(2) level after aspirin 150 mg/day when compared with the corresponding mean values after aspirin 300 mg/day among the resistant patients (66 ± 7.01%, 62 ± 4.34% and 620 ± 64.58 pg/mL, respectively, vs. 26.87 ± 2.85%, 16.5 ± 3.8% and 77 ± 11.3 pg/mL) indicating enhanced response to aspirin after escalating the dose. The presence of atherothrombotic risk factors (hypertension, smoking, family history of ischaemic heart disease and previous MI) were not statistically different between aspirin-resistant and aspirin-sensitive patients. However, there was a highly significant difference between the aspirin sensitive and the resistant patients regarding the other risk factors (diabetes mellitus and dyslipidaemia) (P < 0.01). There is inter-individual variability in response to the antiplatelet effect of standard doses of aspirin (150, 300 mg/day). The response to aspirin 300 mg/day is enhanced in resistant patients when compared to 150 mg/day. There was a significant association between aspirin resistance and atherothrombotic risk factors (diabetes, hyperlipidaemia and obesity).

Protein Microarray Analysis of Nasal Polyps from Aspirin-Sensitive and Aspirin-Tolerant Patients with Chronic Rhinosinusitis

The purpose of this study was to apply protein microarray technology to the study of sinonasal tissue and to identify differential protein expression in nasal polyps from aspirin-sensitive (AS) versus aspirin-tolerant (AT) patients with chronic rhinosinusitis (CRS) and CRS with nasal polyps (CRSwNPs). Nasal polyp specimens were prospectively obtained from two groups of patients with CRSwNP. The test group (AS) consisted of five patients that were diagnosed with CRSwNP and intolerance to aspirin based on medical history and physical exam. The control group (AT) consisted of four AT patients with CRSwNP. Protein was extracted and labeled from harvested polyps and the Sigma Panorama Antibody Microarray-Cell Signaling Kit was used to identify differences in protein expression between the two polyp groups. Western blot analysis was used to validate the results of the protein microarray. The protein microarray showed a greater than twofold change in expression of both beta-adaptin and heat shock protein 70 (HSP70). Western blot analysis confirmed up-regulation of beta-adaptin and HSP70 in nasal polyp tissue from AS patients. Pooled samples of AS and AT nasal polyps evaluated by protein microarray show distinct protein expression profiles in the stress response and receptor-mediated endocytosis pathways. This study establishes the successful application of protein microarray technology to study nasal polyposis, which in turn can be validated by Western blot analysis.

Aspirin-Induced COX-2 Overexpression in Monocytes of Aspirin-Intolerant Patients

Background: We hypothesize that alternate regulation of cyclooxygenase-2 (COX-2) may predispose patients to aspirin-induced exacerbations.Therefore, we want to examine the dynamics of COX-2 up-regulation in whole blood monocytes in the presence and absence of aspirin. Methods: COX-2 expression was evaluated by flow cytometry through intracellular staining of whole blood monocytes with antiCOX-2 antibodies. Enzyme up-regulation was monitored after in vitrostimulation with lipopolysaccharide (LPS) and/or aspirin in 19 aspirin-intolerant (AI) patients (8 aspirin-sensitive asthmatics and 11 urticaria-angioedema patients) and 14 healthy controls. Results: We found significantly higher COX-2 expression levels after stimulation with LPS and aspirin (mean 78.8, range 44.9–92.3; p = 0.0002) in comparison to LPS alone (mean 65.9%, range 33.6–82.6) in AI patients. A comparable, but lower up-regulation was also observed after aspirin stimulation alone (median 2.1%, range 0.5–15.9; p = 0.004) in comparison with baseline values (median 1%, range 0.1–5.4). There was no significant difference in COX-2 expression between LPS and aspirin stimulation (mean 61.8%, range 26.8–89.2; p = 0.09) and LPS stimulation (mean 55.5%, range 28.1–74.3) nor between aspirin stimulation alone (median 0.5%, range 0–8.6; p = 0.8) and baseline values (median 0.4%, range 0–5.4) in healthy control subjects. Conclusions: The main finding of this study is that COX-2 appears to be differentially regulated in aspirin-sensitive patients. What is really new is the observation that aspirin and LPS increase COX-2 expression on blood monocytes of AI asthmatics, a finding in contrast with the lack of an effect of the same stimuli on COX-2 expression on monocytes from healthy subjects.