To study surface expression of P2X7 receptors (P2X7R) on peripheral blood mononuclear cells (PBMC) in patients with primary Sjögren's syndrome (pSS), and its correlation with anxiety and/or depression.
The Hamilton Anxiety Scale (HAMA) and Hamilton Rating Scale for Depression (HRSD) were used to assess 31 patients with pSS. P2X7R expression on the surface of CD14+ and CD14- PBMC, with or without ATP stimulation, was measured by flow cytometry. IL-1β and IL-6 levels in blood plasma and supernatant after ATP stimulation were measured by ELISA. Nineteen patients with rheumatoid arthritis (RA), 18 patients with anxiety and/or depression, and 20 healthy cases were used as controls.
P2X7R expression was detected in all subjects. Compared with no ATP stimulation, significant up-regulation of P2X7R expression on CD14+ PBMC was observed after ATP stimulation in the pSS group only (p=0.001), while on CD14- PBMC there was significant up-regulation in both the pSS (p<0.001) and anxiety/depression (p=0.003) groups. After ATP stimulation, P2X7R expression on CD14+ PBMC in the pSS group was significantly higher than the RA group (p=0.044), anxiety/depression group (p=0.004) and healthy controls (p=0.002). Moreover, in the pSS group, P2X7R expression on CD14+ PBMC was significantly positively correlated to IL-1β supernatant levels (r=0.447, p=0.025). Overall, there were 45.2% (14/31) patients with anxiety and 32.3% (10/31) with depression, in the pSS group. P2X7R expression on CD14- PBMC was significantly positively correlated to scores of anxiety (r=0.344, p=0.030) and depression (r=0.319, p=0.045).
Surface expression of P2X7R on PBMC in patients with pSS was significantly higher than controls, suggesting P2X7R may contribute to the complex pathogenesis of pSS and also anxiety and/or depression.