Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Magomedov, A.
Identification of antigen-specific natural killer T cells in patients with antiphospholipid antibody syndrome
Humanmedizin; [ Diplomarbeit ] Graz Medical University; 2017. pp. 75
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- Autor*innen der Med Uni Graz:
- Betreuer*innen:
- Graninger Winfried
- Stradner Martin Helmut
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- Abstract:
- Background Antiphospholipid Syndrome (APS) is an autoimmune disease, characterized by arterial or venous thrombosis, pregnancy complications such as recurrent pregnancy loss and the occurrence of antiphospholipid antibodies. Research indicates that antiphospholipid antibodies such as anti-cardiolipin and anti-ß2-glycoprotein 1 play a crucial role in the pathogenesis of antiphospholipid syndrome. However, little is known about their emergence, regulation and pathological effects. Recently published mouse studies suggest that a T cell subset called natural killer T cells (NKT cells) with the capability to recognize lipid antigens could have a decisive influence on the regulation of the anti-cardiolipin antibody production. In the following work, we hypothesize the existence of such NKT cells in humans particular in patients with APS. Besides the detection of cardiolipin recognizing NKT cells, this study aims at providing a better understanding of their role in APS. Methods A prospective study on 8 patients with APS and 11 healthy controls was performed to identify and characterize cardiolipin binding NKT cells via flow cytometry. Cardiolipin (CL) loaded CD1d tetramer was used to determine the prevalence of CL on patient with APS and healthy group in the peripheral blood. Additionally, the phenotype of the CL-binding NKT cells was analysed by using distinct surface markers. A stimulation assay was performed in cell culture to investigate the capability of CL NKT cell activation. The extent of proliferation was measured by means of intracellular Ki67 staining. The production of cytokines (GM-CSF, Granzyme B, IFN-¿, IL-4, IL-6, IL-10, IL-17A, IL-21 and TNF-a) was measured via a Multiplex Immunoassay upon stimulation with CL. Results We identified CL-binding NKT cells in peripheral blood of APS patients and healthy individuals using CL loaded CD1d tetramers (0,028 % [± 0.01] of total T cell population) Moreover, we showed that this novel T cell subgroup are neither invariant NKT cells nor ¿d T cells, which are known for their potential to recognize lipid antigens. Patient with APS had elevated numbers of CL-binding NKT cells (0,024 % [± 0.006] of total T cell population vs. 0,016 % [± 0.007]; p = 0,017) in peripheral blood compared to healthy control group. The exposure of CL recognizing NKT cells to CL in stimulation assays caused an up-regulation of Ki67 protein expression in contrast to untreated cells. (20,37 % of total CL NKT Cells [± 13,40]) vs. 8.08 % [± 4,42] p = 0,027). Treatment with CL induced suppression of basal cytokine secretion. Conclusion We describe a novel subpopulation of T cells recognizing CL as an antigen. Moreover, this subset occurred more frequently in APS patients than in healthy individuals, which suggests that these NKT cells could play a role in the production of anti-CL antibodies. The up-regulation of Ki67 in healthy individuals upon the substitution of CL also indicates that CL can serve as an antigen eliciting an immune response. The suppression of production of several cytokines suggests that CL not only affects the NKT cells but also has extensive influence on superordinate immunological processes. Therefore, further studies are needed to elucidate the exact role of CL-binding NKT in the pathogenesis of APS.