Antithrombotic triple therapy and coagulation activation at the site of thrombus formation: a randomized trial in healthy subjects.

BACKGROUND: Patients with acute coronary syndrome and concomitant atrial fibrillation may require antithrombotic triple therapy but clinical evidence of safety and efficacy is poor. We have therefore studied the combination of different antithrombotic medicines for coagulation activation in an in vivo model in the skin microvasculature. METHODS AND RESULTS: Platelet activation (ß-thromboglobulin [ß-TG]) and thrombin generation (prothrombin fragment 1 + 2 [F1+2 ], thrombin-antithrombin complex [TAT]) were studied in an open-label, randomized, parallel group trial in 60 healthy male subjects (n = 20 per group) who received ticagrelor and acetylsalicylic acid (ASA) in combination with dabigatran (150 mg bid), rivaroxaban (20 mg od) or phenprocoumon (INR 2.0-3.0). Coagulation biomarkers in shed blood were assessed at 3 h after monotherapy with the medicines under study, at 3 h after triple therapy dosing and at steady state trough conditions. Single doses of ticagrelor, dabigatran or rivaroxaban caused comparable decreases in shed blood ß-TG and were more pronounced than phenprocoumon at an INR of 2.0-3.0. In contrast, thrombin generation was more affected by rivaroxaban and phenprocoumon than by dabigatran. During triple therapy a similarly sustained inhibition of platelet activation and thrombin generation with a maximum decrease of ß-TG, F1+2 and TAT at 3 h post-dosing was noted, which remained below pre-dose levels at trough steady state. CONCLUSION: A triple therapy at steady state with ticagrelor plus ASA in combination with dabigatran or rivaroxaban is as effective as a combination with phenprocoumon for platelet activation and thrombin generation in vivo.

The green tea extract epigallocatechin gallate is able to reduce neutrophil transmigration through monolayers of endothelial cells.

Green tea is widely used in Asia and has also become popular in Western countries. The influence of green tea extracts on leukocytes is not well understood. Leukocytes play a crucial role in the process of inflammation. They migrate from the intravascular space into the tissue to attack micro-organisms. The aim of the current study was to investigate the influence of epigallocatechin gallate on leukocyte transmigration through endothelial cell monolayers and thereby evaluate its potential role in the inflammatory process. Human umbilical vein endothelial cells were cultured on microporous membranes to achieve a monolayer. Freshly isolated neutrophils from healthy subjects were measured with a migration assay. The amount of untreated neutrophils migrating through untreated endothelial cell monolayers was used as control and set as 100%. Neutrophils and/or endothelial cell monolayers were pre-treated with epigallocatechin gallate using relevant, as well as higher and lower concentrations. The relevant plasma concentration of epigallocatechin gallate was able to significantly inhibit neutrophil migration through endothelial cell monolayers (69 +/- 6.4% SD; p < 0.05 compared to control), when both cell types (leukocytes and endothelial cell monolayer) were treated. This is similar to the situation after resorption in-vivo. Treating either neutrophils or endothelial cell monolayers alone led to significant reductions in migratory response (only neutrophils treated: 86 +/- 8.1% SD, p < 0.05; only endothelial cell monolayers: 77 +/- 6.1%, p < 0.05). In conclusion, epigallocatechin gallate was identified as a potent inhibitor of leukocyte migration through endothelial cell monolayers. The treatment of both cell types showed an additive effect. Endothelial cells seem to be more affected than neutrophils. Further clinical investigations are necessary to understand the potential clinical consequences.

IgE antibodies to recombinant pollen allergens (Phl p 1, Phl p 2, Phl p 5, and Bet v 2) account for a high percentage of grass pollen-specific IgE.

BACKGROUND: Pollen from different grass species are some of the most potent elicitors of Type I allergy worldwide. The characterization of antigenic structures and IgE epitopes common to different grass species is relevant to define reagents for diagnosis and specific therapy of grass pollen allergy. OBJECTIVE: The purpose of this study was to estimate the percentage of IgE directed to common, cross-reactive, or both types of epitopes shared by recombinant pollen allergens (Phl p 1, Phl p 2, Phl p 5, and Bet v 2) and natural pollen extracts from nine different monocots (Anthoxanthum odoratum, Avena sativa, Cynodon dactylon, Lolium perenne, Phragmites australis, Poa pratensis, Secale cereale, Triticum sativum, Zea mays) by using sera from different populations. METHODS: Natural pollen extracts from nine different monocot species were characterized regarding their allergen contents by using specific antibodies and by IgE immunoblot inhibition with recombinant allergens. The percentage of grass pollen-specific IgE that was preabsorbed with a combination of recombinant timothy grass pollen allergens (Phl p 1, Phl p 2, and Phl p 5) and recombinant birch profilin (Bet v 2) was determined by ELISA in sera from 193 European, American, and Asian subjects. RESULTS: IgE to recombinant pollen allergens accounted for a mean 59% of grass pollen-specific IgE. A lower inhibition of IgE binding to certain natural extracts (C. dactylon and Z. mays) could be attributed to the absence of immunologically detectable group 5 and group 2 allergens in these species. CONCLUSION: We define four recombinant pollen allergens that account for a substantial proportion of grass pollen-specific IgE. The recombinant pollen allergens characterized may represent candidates not only for diagnosis but also for patient-tailored immunotherapy of grass pollen allergy.

Natural latex, grass pollen, and weed pollen share IgE epitopes.

BACKGROUND: Because of the frequent use of natural latex products, IgE-mediated reactions to latex proteins represent an important health threat in industrialized countries. Although several latex allergens have been characterized and IgE cross-reactivities with allergens present in plant-derived food have been described, limited information is available regarding the presence of common IgE-binding components in latex and plant pollen. METHODS: By using serum IgE from 56 individuals with latex allergy, the IgE-binding components in ammoniated latex milk and latex glove extracts were characterized by immunoblotting. The presence of cross-reactive IgE-binding components in the different latex extracts, extracts from mugwort, ragweed, timothy grass pollen, and recombinant birch pollen allergens (Bet v 1 and Bet v 2 [birch profilin]) was studied by immunoblot inhibitions and quantitative competition experiments. The involvement of carbohydrates in the constitution of cross-reactive IgE epitopes was studied by periodate treatment of extracts. RESULTS: Although sera from certain individuals with latex allergy showed IgE reactivity with protein bands of different molecular weights in Western-blotted latex milk and glove extracts, both extracts contained common IgE epitopes. Although preincubation with recombinant Bet v 1 and Bet v 2 did not significantly inhibit IgE binding to latex proteins, weed and, in particular, timothy grass pollen extract strongly inhibited IgE binding to latex allergens. The cross-reactive IgE epitopes were sensitive to periodate treatment. CONCLUSIONS: Mugwort, ragweed, and timothy grass pollen share IgE epitopes with glycoprotein latex allergens. The presence of common epitopes might in part explain clinical symptoms in patients allergic to pollen on contact with latex.