1.
A switch to a raltegravir containing regimen does not lower platelet reactivity in HIV-infected individuals.
van der Heijden, WA, van Crevel, R, de Groot, PG, Urbanus, RT, Koenen, HJPM, Bosch, M, Keuter, M, van der Ven, AJ, de Mast, Q
AIDS (London, England). 2018;(17):2469-2475
Abstract
OBJECTIVE Platelet hyperreactivity and increased platelet-monocyte aggregation (PMA) are associated with increased cardiovascular risk and inflammation. In a previous cross-sectional study, individuals using a raltegravir (RAL)-based regimen were found to have reduced platelet reactivity and PMA compared with other antiretroviral regimens. Our aim was to investigate whether switching from a nonintegrase inhibitor regimen to a RAL-based regimen reduces platelet reactivity or PMA. DESIGN An investigator initiated, single-centre, prospective randomized, open-label, blinded endpoint trial. METHODS Forty HIV-infected adults using a nonintegrase inhibitor containing regimen with undetectable viral load were randomized to either continue their regimen or switch to a RAL-based regimen for 10 weeks, continuing the same backbone. The primary outcome was the change in platelet reactivity at week 10, which was determined as the expression of the platelet activation marker P-selectin and binding of fibrinogen before and after ex-vivo stimulation with different platelet agonists. Secondary outcomes included PMA, plasma markers of platelet activation and markers of inflammation and immune cell activation. RESULTS Twenty-one participants were enrolled in the continuation group and 19 in the RAL group. Baseline characteristics were comparable between groups. There were no differences in the change in platelet reactivity to either platelet agonist at week 10, nor in plasma markers of platelet activation. PMA, C-reactive protein, T-cell activation (CD38HLA-DR) and monocyte (CD14CD16) subsets. CONCLUSION Switching a nonintegrase inhibitor containing regimen to a RAL-based regimen does not reduce platelet reactivity, platelet-leukocyte aggregation, inflammation and immune activation in virologically suppressed HIV-infected individuals. CLINICAL TRIAL NUMBER NCT02383355.
2.
Diagnosis of platelet function disorders: A standardized, rational, and modular flow cytometric approach.
Andres, O, Henning, K, Strauß, G, Pflug, A, Manukjan, G, Schulze, H
Platelets. 2018;(4):347-356
Abstract
A high proportion of patients with mucocutaneous bleeding diathesis and suspected inherited or acquired platelet disorder remain without diagnosis even after comprehensive laboratory testing. Since flow cytometry allows investigation of resting and activated platelets on the single cell level by requiring only minimal amounts of blood, this method has become an important assay within the diagnostic algorithm, especially in pediatrics. We therefore developed a standardized and modular flow cytometric approach that contributes to clarify impaired platelet function in a rational step-by-step manner. Due to simultaneous analysis of four fluorophores in a basic panel design, we are able to readily detect the most common and clinically significant platelet disorders: Glanzmann thrombasthenia or Glanzmann-like diseases (fibrinogen receptor GPIIb-IIIa), Bernard-Soulier syndrome (von Willebrand-factor receptor complex GPIb-IX-V) and less well characterized β1-integrins that serve as the collagen, laminin or fibronectin receptor (CD29-CD49b, e and f, respectively). Platelet reactivity was investigated in response to the agonists adenosine diphosphate (ADP) and thrombin receptor activator peptide 6 (TRAP6) in suboptimal and optimal concentrations by quantifying surface expression of activation markers CD62P and CD63 as well as binding of PAC-1 antibody to the high affinity conformation of the fibrinogen receptor. For advanced diagnostic questions, several further modules were implemented: (i) calcium mobilization for evaluation of early signal transduction, (ii) a kinetically resolved mepacrine assay for estimation of delta-granule content and release, and (iii) a module to determine platelet reactivity upon additional agonists like the thromboxane A2-analogue U46619 or collagen. Blood withdrawn from a healthy control cohort allowed generating preliminary standard values for all parameters. The modules were validated by analysis of patients with known or suspected platelet defects (leukocyte-adhesion deficiency type III, Wiskott-Aldrich syndrome, acute myeloid leukemia, sickle cell disease and chronic immune thrombocytopenia).
3.
Platelet-released growth factors induce psoriasin in keratinocytes: Implications for the cutaneous barrier.
Bayer, A, Lammel, J, Lippross, S, Klüter, T, Behrendt, P, Tohidnezhad, M, Pufe, T, Cremer, J, Jahr, H, Rademacher, F, et al
Annals of anatomy = Anatomischer Anzeiger : official organ of the Anatomische Gesellschaft. 2017;:25-32
Abstract
Millions of patients around the world suffer minor or major extremity amputation due to progressive wound healing complications of chronic or infected wounds, the therapy of which remains a challenge. One emerging therapeutic option for the treatment of these complicated wounds is the local application of an autologous thrombocytes concentrate lysate (e.g. platelet-released growth factors ((PRGF)) or Vivostat PRF®) that contains a multitude of chemokines, cytokines and growth factors and is therefore supposed to stimulate the complex wound healing process. Although PRGF and Vivostat PRF® are already used successfully to support healing of chronic, hard-to-heal and infected wounds the underlying molecular mechanisms are not well understood. Psoriasin, also termed S100A7, is a multifunctional antimicrobial protein expressed in keratinocytes and is involved in various processes such as wound-healing, angiogenesis, innate immunity and immune-modulation. In this study, we investigated the influence of PRGF on psoriasin expression in human primary keratinocytes in vitro and the influence of Vivostat PRF® on psoriasin expression in experimentally generated skin wounds in vivo. PRGF treatment of primary keratinocytes caused a significant concentration- and time-dependent increase of psoriasin gene and protein expression in vitro that were partially mediated by the epidermal growth factor receptor (EGFR) and the interleukin-6 receptor (IL-6R). In accordance with these cell culture data, Vivostat PRF® induced a significant psoriasin gene and protein expression when applied to artificially generated skin wounds in vivo. The observed psoriasin induction in keratinocytes may contribute to the wound healing-promoting effects of therapeutically used thrombocyte concentrate lysates.