Chronic spontaneous urticaria (CSU) is a skin disease caused by mast cells that produce inflammatory mediators. Immune checkpoint receptors such as program death-1 (PD-1) and T-cell immunoglobulin and mucin domain 3 (TIM-3) are essential for the pathophysiology of many autoimmune and allergic diseases. The aim of this study was to investigate the expression of PD-1 and TIM-3 in CSU patients and their relationship to the anti-inflammatory cytokines (TGF-β and IL-10). In the current study, peripheral blood mononuclear cells (PBMCs) from CSU patients and healthy individuals were used and the Urticaria Activity Score 7 (UAS7) was used to assess disease severity. TaqMan-based RT-PCR was used to assess the expression of TIM-3 and PD-1 as well as the anti-inflammatory cytokines transforming growth factor-β (TGF-β) and IL-10. The protein concentrations of TGF-β and IL-10 were also measured by ELISA. The relationship between the expression of TIM-3 and PD-1 as well as TGF- β and IL-10 and the severity of the disease was investigated. The results showed that PD-1 mRNA expression was significantly increased in CSU patients (P<0.0001), while TGF- β and IL-10 levels were higher in CSU patients, but this difference was not significant (p=0.638, p= 0.798). The increase in protein level of IL-10 was significant (P<0.0001). There was also a positive correlation between the expression of PD-1 and TGF- β molecules and disease activity (P=0.0043, P=0.0018). In conclusion, the study found that the immune system expresses inhibitory molecules and anti-inflammatory cytokines to control disease severity. The higher expression of PD-1 molecules and IL-10 is associated with disease severity, suggesting that the immune system is trying to control inflammation and reduce disease severity.
Keywords: CSU; IL-10; PD-1; TGF-β; TIM-3; UAS7.
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