C-reactive protein (CRP) rs3093059C predicts poor mizolastine response in chronic spontaneous urticaria patients with elevated serum CRP level.

Chronic spontaneous urticaria (CSU) is a frequent disorder with recurrent itchy wheals and/or angioedema, and nearly 35% patients respond poorly to non-sedating H1 antihistamine treatment. CRP gene encodes the C-reactive protein, which is involved in the pathogenesis of CSU. To investigate the impacts of CRP polymorphisms on the susceptibility and therapeutic efficacy in the South Han CSU patients, we enrolled 145 CSU patients in our study. After 4-week non-sedating H1 antihistamine monotherapy treatment, more than 50% reduction of the severity score is considered as effective, or else non-effective. The CRP rs3093059T/C and rs2794521G/A genotypes of patients were determined by Sequenom MassARRAY. Functional studies including relative luciferase assay and β-hexosaminidase assay were conducted in HEK293T cells or RBL-2H3 cells to explore the function of variants. Forty (62.50%) CSU patients were effective when treated with mizolastine, and 55 (72.4%) patients were effective in the desloratadine group. We found that the patients carried with rs3093059TT genotype were significantly associated with good response (OR = 4.20, P = 0.015), had lower serum CRP, IL-6 and TNF-α levels than the CT/CC genotypes. In vitro, the rs3093059C allele exhibited significantly higher luciferase activity than wild allele (P < 0.001). From the β-hexosaminidase assay, we observed the inhibiting degranulation effects by mizolastine and this effect is weakened when with a higher dose CRP in RBL-2H3 cells. Our findings suggested that CSU patients carrying the rs3093059C allele may respond poorly to mizolastine with elevated serum CRP level.