Preliminary Investigation about the Expression of G Protein-Coupled Receptors in Platelets from Patients with Chronic Immune Thrombocytopenic Purpura

Objective: The objective of this study was to determine the expression of G protein-coupled receptors (GPCRs) in platelets from adult patients with chronic immune thrombocytopenic purpura (ITP). Methods: Peripheral blood samples were collected from 40 patients with chronic ITP in the Second Affiliated Hospital of Shantou University Medical College, and 40 peripheral blood samples from healthy volunteers were collected; expressions of the adenosine diphosphate receptors (P2Y1 and P2Y12), alpha-2A adrenergic receptor (α2A-AR), and thromboxane A 2 receptor (TP) in platelets were detected by flow cytometry. Gα protein, protease-activated receptor 1 (PAR1), and protease-activated receptor 4 (PAR4) were analyzed by Western blot and analyzed statistically. Results: Flow cytometry measurements of mean fluorescence intensities showed platelets from patients with chronic ITP, compared to healthy individuals, had significantly higher levels of P2Y1 (31.4 ± 2.2 vs. 7.8 ± 0.8), P2Y12 (29.6 ± 2.1 vs. 7.2 ± 1.3), α2A-AR (25.8 ± 2.9 vs. 9.8 ± 0.9), and TP (39.8 ± 3.1 vs. 4.7 ± 0.6) (all p < 0.01). Similarly, integrated optical density analysis of Western blots showed that platelets from patients with chronic ITP had significantly higher levels of Gα (1046.3 ± 159.96 vs. 254.49 ± 39.51), PAR1 (832.98 ± 98.81 vs. 203.92 ± 27.47), and PAR4 (1518.80 ± 272.45 vs. 431.27 ± 41.86) (all p < 0.01). Conclusion: Expression of GPCRs is increased in platelets from patients with chronic ITP, suggesting that platelets of chronic ITP may participate in the complicated biological process by means of GPCR-mediated signaling pathways.