Protein profiling analysis of platelets in hypercoagulable state of β-thalassemia/HbE patients

Abstract

β-thalassemia/HbE is an inherited hemolytic anemia caused by defect in β-globin synthesis resulting in accumulation of excess α-globin chains in red blood cells. A hypercogulable state leading to high risk of thromboembolic event is one of the most common complications observed in this disease, particularly in patients with splenectomy. Previous studies suggested that increased platelet activation and coagulation factors in β-thalassemia/HbE intermediate patients promote the hypercoagulable state. However, the hypercoagulable state as well as the molecular mechanism regarding this pathogenesis in β-thalassemia/HbE is not yet well understood. This study aimed to identify proteins related to platelet activation and to hypercoagulable state in the β-thalassemia/HbE patients. Fifteen non-splenectomized β-thalassemia/HbE, 8 splenectomized β-thalassemia/HbE and 20 normal controls were recruited to determine the hypercoagulation state including detection levels of platelet activation and prothrombin fragment 1+2. The proteomic analysis was performed to compare to platelet proteome between the β-thalassemia/HbE patients and normal subjects. The levels of platelet activation and prothrombin fragment 1+2 in β- thalassemia/HbE patients were significantly increased as compared to normal controls (p<0.05). Moreover, platelet activation strongly correlated with levels of prothrombin fragment 1+2 (rs = 0.6146, p < 0.0018). Proteomic analysis revealed a total of 19 differentially expressed proteins. Most of the up-regulated proteins are 10 platelets cytoskeleton proteins. In addition, 1 immune activation related protein, 2 proteins involved in heme and globin synthesis and 2 antioxidant enzymes were also up-regulated in the β-thalassemia/HbE patients. A protease inhibitor was found to be down-regulated in β-thalassemia/HbE. Additionally, significantly elevated expression of a chaperone protein (Hsp70), a fibrinogen receptor (integrin αIIb) and a chemokine (PF4) was observed in β-thalassemia/HbE as compared to normal controls and those proteins were positively correlated with serum ferritin levels (p<0.05). In conclusion, proteins related to platelet activation as well as the hypercoagulable state of β-thalassemia/HbE have been described. The data from this study will lead to novel insights to understand the pathophysiological conditions in the β-thalassemia/HbE patients. The novel proteins in platelet activation may serve as predictors of the thrombosis state and improve treatment modalities for β-thalassemia/HbE patients