Relationship between Inflammation and Aspirin and Clopidogrel Antiplatelet Responses in Acute Ischemic Stroke.

OBJECTIVE: We measured serum levels of proinflammatory/prothrombotic markers P-selectin, CD40L, matrix metalloproteinase 9 (MMP-9), intracellular adhesion molecule 1 (ICAM-1), and interleukin (IL)-6 in ischemic stroke patients, correlating their levels with the results of aspirin (ASA) and clopidogrel antiplatelet responses, using 3 "point of care" platelet function instruments, thromboelastograph (TEG), Accumetrics (ACU), and impedance aggregometer (IMP). METHODS: Patients on chronic ASA regimen at the time of stroke were switched to 300 mg clopidogrel loading dose and 75 mg clopidogrel maintenance dose. Serum levels of the aforementioned inflammatory mediators were measured in 51 patients at baseline (on ASA regimen), and at 26 ± 5 hours and 64 ± 18 hours postclopidogrel administration by enzyme-linked immunosorbent assay. RESULTS: P-selectin, CD40L, and MMP-9 serum levels were reduced; ICAM-1 and IL-6 serum levels showed no difference postclopidogrel administration relative to baseline. Patients' stratification based on ASA dose showed more significant reductions in P-selectin, CD40L, and MMP-9 serum levels postclopidogrel administration in patients who were on baseline 81 mg ASA, as compared to patients on 325 mg ASA. Measurement with TEG was sensitive for correlating ASA antiplatelet responses to serum levels of inflammatory markers, whereas measurements with ACU and IMP were sensitive for correlating clopidogrel antiplatelet responses to serum levels of inflammatory markers. CONCLUSION: Clopidogrel exerts both platelet-dependent and platelet-independent anti-inflammatory effects. The association between platelet function and inflammation depends on the platelet function analyzer, the type of antiplatelet agent, the nature of the inflammatory marker, and the time of measurement relative to the time of drug administration.

Clopidogrel responsiveness in stroke patients on a chronic aspirin regimen.

This study evaluated the antiplatelet effects of clopidogrel (CPG) in patients sustaining acute ischemic stroke who were already receiving chronic outpatient aspirin therapy (81-325 mg/day). Platelet function was measured using 3 different "point-of-care" platelet function analyzers: the Thrombelastograph hemostasis system, the Accumetrics VerifyNow system, and the Chronolog 570VS impedance aggregometer. Platelet function was assessed before administration of a 300-mg CPG loading dose and again at 26 hours and 64 hours after this loading dose along with a 75-mg daily maintenance dose. All 3 instruments detected marked inhibition of platelet function at 26 hours and 64 hours after CPG administration. There were significant variations among the 3 instruments in monitoring antiplatelet responses to aspirin and CPG; however, these variations were eliminated when the platelet function results were corrected for baseline platelet variability. The percentage of patients who were poor responders to CPG after switching from aspirin depended on the measurement instrument used, but was higher at 26 hours after CPG administration than at 64 hours after CPG administration. Our findings indicate that poor response to antiplatelet agents in general, and to CPG in particular, is a function of the measuring instrument. The correction for baseline platelet variability results in similar levels of platelet inhibition measured by the 3 platelet function analyzers. Future studies are warranted to examine the association between ex vivo CPG-induced platelet inhibition and clinical outcomes in patients with ischemic stroke.

AGE-RAGE in multiple sclerosis brain.

This pilot study used immunohistochemical techniques to investigate the advanced glycation end-product (AGE) Nepsilon-(carboxymethyl)lysine (CML) and its receptor (RAGE) in the brains of multiple sclerosis (MS) patients, comparing them with the brains of patients with Alzheimer's disease (AD) (positive controls) and with age-matched control subjects (negative controls). Postmortem slides derived from the hippocampi of MS patients, AD patients, and controls were stained with monoclonal antibodies for CML and human RAGE. Results showed increased AGE and RAGE immunostaining in the hippocampi of MS patients, similar to AD patients.

Reduced expression of membrane-bound (m)RAGE is a biomarker of multiple sclerosis disease progression.

OBJECTIVES: This study is one in series measuring RAGE axis (receptor for advanced glycation end products, its isoforms, and ligands) as a biomarker in multiple sclerosis (MS). We identified and quantified membrane-bound RAGE (mRAGE) expression levels on freshly isolated PBMCs and its subpopulation (monocytes and T cells), and determined the relationship between mRAGE expression levels and MS disease severity. MATERIALS AND METHODS: mRAGE expression was determined for 28 MS patients and 16HCs, by flow cytometry, using fluorochrome unconjugated primary RAGE monoclonal antibody and a polyclonal secondary antibody conjugated to R-Phycoerythrin (PE). RESULTS: After adjusting for multiple comparisons and correcting for group differences in age and gender, MS patients showed higher percentages of mRAGE-positive on PBMCs (12.4±2.1 vs. 4.08±0.8, P=0.02), monocytes (37.4±5.8 vs. 20.1±5.0, P=0.08) and T cells (4.1±1.2 vs. 2.1±0.3, P=0.05). SPMS patients' showed lower percentages of RAGE-positive monocytes (13.7±5.5 vs. 49.5±6.6, P=0.0006) and RAGE-positive T cells (4.1±1.8 vs. 6.6±1.5, P=0.04) than RRMS patients. We observed a negative relationship between the percentages of mRAGE-positive PBMCs and MS severity scale (MSSS) (r=-0.39, P=0.04), monocytes and EDSS (r=-0.48, P=0.01), monocytes and MSSS (r=-0.58, P=0.001), and T cells and MSSS (r=-0.40, P=0.04). Monocytes expression of mRAGE showed 0.811 area under the curve (95% CI: 0.64-0.98) sensitivity/specificity for MSSS. CONCLUSION: The reduced mRAGE expression on PBMCs in general, and on monocytes in particular, can be used as biomarker of MS disease severity and progression.

High-mobility group box 1 in multiple sclerosis.

This study is one in series determining the potential of RAGE axis (receptor for advanced glycation end products, isoforms, ligands) as a biomarker in multiple sclerosis (MS). We evaluated serum levels of RAGE ligand, the high-mobility group box (HMGB)1 in MS patients, and assessed the correlation between HMGB1 serum levels and the use of disease-modifying drugs (DMDs), and between HMGB1 serum levels and indicators of MS disease severity. HMGB1 serum levels were compared between 96 (23 males) MS patients and 34 age- and gender-matched healthy controls (HCs) using enzyme-linked immunosorbent assays. DMD-naïve MS patients had significantly higher HMGB1 serum levels compared with DMD-treated (P = 0.04) and compared with HCs (P = 0.01). HMGB1 serum levels were not significantly different between total MS patients (DMD-naïve plus DMD-treated) and HCs (P = 0.09). DMD-naïve MS patients in clinical relapse tended to have lower HMGB1 serum levels than clinically stable RRMS patients (P = 0.07). HMGB1 serum levels showed 0.65 area under the curve (95 % CI 0.55-0.95) sensitivity/specificity for MS clinical relapse. The role of HMGB1 in MS disease pathology and DMD modulation of this protein warrant further investigations.

Disease modifying drugs modulate endogenous secretory receptor for advanced glycation end-products, a new biomarker of clinical relapse in multiple sclerosis.

OBJECTIVES: This study is one in a series measuring RAGE axis (receptor for advanced glycation end products, its isoforms, and ligands) and its potential as a biomarker in multiple sclerosis (MS). We evaluated serum levels of the endogenous secretory RAGE (esRAGE) in MS patients and assessed the relationship between esRAGE levels and the use of disease modifying drugs (DMDs), and between esRAGE levels and indicators of MS disease severity. METHOD: esRAGE serum levels were compared between 98 MS patients and 34 healthy controls (HCs) using ELISA. RESULTS: esRAGE serum levels were similar between MS and HCs. DMD-treated patients had higher esRAGE serum levels than DMD-naïve patients (395.7±38.6pg/ml vs. 299.2±20.1pg/ml, P=0.02). DMD-naïve, primary progressive (PP) patients had higher esRAGE serum levels, than relapsing remitting (RR) (P=0.02) and secondary progressive (SP) (P=0.04) patients; RRMS patients in clinical relapse had lower esRAGE serum levels than clinically stable patients (219.7±30.0pg/ml vs. 338.2±31.6pg/ml, P=0.02). In a univariate regression analysis of DMD-naïve MS patients, esRAGE serum levels inversely correlated with the rate of clinical relapse (r=-0.44, P=0.006), MS severity scale (MSSS) (r=-0.32, P=0.03), and expanded disability status scale (EDSS) (r=-0.251, P=0.07). CONCLUSION: esRAGE serum levels are modulated by DMDs. The serum levels may be a useful biomarker of MS clinical relapse.

Quantitative and qualitative pleiotropic differences between Simvastatin single and Vytorin combination therapy in hypercholesterolemic subjects.

AIMS: This cross-sectional study tested the hypothesis that treatment with the combination of Ezetimibe/Simvastatin (Vytorin) leads to broader changes in the expression levels of immunomodulatory genes as compared to Simvastatin monotherapy. METHODS: Illumina's GenomeStudio gene expression module was used to compare gene profiles of Vytorin and Simvastatin in the peripheral blood mononuclear cells of 20 hypercholesterolemic subjects. RESULTS: The characteristics of the immunomodulatory genes, which were altered by Vytorin, differed from those genes which were altered by Simvastatin. Vytorin mostly altered the expression levels of genes related to inflammation/oxidative stress; it downregulated the NF-KappaB and upregulated the expression of anti-inflammatory cytokine, IL-10, and anti-oxidant enzymes, GPX1 and SOD2, but also upregulated the expression levels of genes involved in cellular activation, adhesion, and coagulation cascade, including VWF, F7, PF4, PF4V1 SELP, ITGB3, ITGB5. Simvastatin mostly altered the expression levels of genes related to cellular apoptosis/proliferation. It upregulated the expression levels of apoptosis-related genes APAF1, BAX, IER3, and CSF1R, and downregulated the expression levels of genes related to cellular proliferation, including PTN and CD69. Treatment with Vytorin combination therapy modulated lipid profile and serum levels of the C-reactive protein more effectively, than treatment with Simvastatin monotherapy. CONCLUSION: The nature of the pleiotropic effects may play a role in Vytorin's and Simvastatin's clinical efficacies.