| Abstract |
Immune thrombocytopenia (ITP) is one of the most common blood diseases as well as the commonest acquired bleeding disorder in childhood. ITP is pathophysiologically characterized by a low circulating platelet count due to the production of autoantibodies against platelet glycoproteins, especially against GPIIb/IIIa and Ib/IX, followed by their destruction via the reticuloendothelial system.(1) Newly diagnosed ITP is defined as up to 3 months from diagnosis, persistent ITP is 3–12 months from diagnosis, and chronic is defined as ITP lasting more than 12 months. Approximately 3 out of 4 children will recover from ITP within 12 months from diagnosis.(2)
Apoptosis is a physiologic mechanism of programmed cell death that is crucial for controlling cell number during development and the entire lifetime of an organism. Deregulation of apoptosis signaling may compromise the homeostasis of an organism and cause a wide range of diseases. Apoptosis is triggered through either the intrinsic or extrinsic pathway. (3) Fas is a transmembrane molecule belonging to the tumor necrosis factor (TNF) receptor superfamily. Fas ligation by FasL induces programmed cell death (PCD) in several lymphoid cell lines and may play a role in immune response contol, lymphocyte life span regulation and induction of peripheral tolerance. Moreover, Fas is involved in cytotoxic T-lymphocyte and Th1 cell cytotoxitcity, which is partially due to the interaction of FasL expressed by activated cytotoxic cells with Fas expressed by target cells.(4) Caspases are cysteine proteases that play a central role in apoptosis. Caspase-8 and caspase-10 may be the first enzymes in the proteolytic cascade that are activated by FAS ligand and tumor necrosis factor. According to the literature, mutations in either CASP8 or CASP10 (being implicated in programming life and death of immune cells) influence immune surveillance of malignancies and cause lymphoproliferation (autoimmune lymphoproliferative syndrome type IIA and B).(5)
Aim: Aim of this study is to identify if the polymorphisms of FAS, CASP8 and CASP10 play a role in the emerge of Immune Thrombocytopenia in children and adolescents.
Materials and Methods: In this study 30 children and adolescents with Immune Thrombocytopenia and 60 healthy individuals as control group were included. At first, extraction DNA out of peripheral blood was performed, which then was analysed by Polymerase Chain Reaction (PCR). The PCR was followed by digestion using selected restricted enzymes in order to genotype individuals for the SNPs under study. For the FAS (rs2234767) and CASP8 (rs1045485) polymorphisms, the restriction enzyme BstUI was used. For the CASP10 polymorphism (rs13006529), the enzyme SspI was used. Digestion products were analyzed by agarose gel electrophoresis and statistical analysis was performed by using the GraphPad Prism (GraphPad Software, San Diego, CA, USA) program.
Results: Statistical analysis of data showed that allele T of CASP10 rs13006529 SNP was associated with the development of ITP. It’s effect may be related to the role of caspase 10 in the endogenous pathway of apoptosis as well as its involvement in the process of autophagy. However, no association for the studied SNPs of FAS and CASP8 genes was detected.
Conclusions: Allele T of CASP10 rs13006529 SNP appeared to have a statistically significant difference between patients and controls, thus suggesting its role in the development of the ITP. As regards with the FAS (rs2234767) and CASP8 (rs1045485) SNPs no association with ITP was observed. However, these results are considered as early due to the small number of samples examined. Further analysis of a higher number of patients/controls is needed in order to clarify the role of the SNPs under study in children and adolescents with ITP.
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Η μελέτη των πολυμορφισμών του FAS, της κασπάσης 8 (CASP8) και 10 (CASP10) στη θρομβοπενία ανοσολογικής αρχής παιδιών και εφήβων
