Supplementary Material for: Proteinase-activated receptor 2 (PAR-2) expression and F2RL1 genetic variants are associated with asthma: a case-control study in the Chinese population

Asthma is a chronic respiratory disorder characterized by airway inflammation, hyperresponsiveness, and reversible airflow obstruction. Despite therapeutic strategies, asthma remains inadequately controlled in many patients. Genetic predisposition plays a significant role in asthma pathogenesis, and the Proteinase-Activated Receptor 2 (PAR-2), encoded by the F2RL1 gene, has been associated with asthma. However, the role of PAR-2 and F2RL1 variants in the Chinese population remains unclear. This study aims to investigate the relationship between common F2RL1 polymorphisms and PAR-2 expression, and their association with asthma susceptibility and clinical severity in a Chinese population. This study enrolled 250 clinically diagnosed Chinese patients with asthma and matched healthy controls of a similar age and geographical region. Four single nucleotide polymorphisms in the F2RL1 gene (rs1529505, rs631465, rs2242991, and rs2243057) were genotyped using the TaqMan genotyping method. PAR-2 mRNA expression was quantified through real-time PCR in intravenous blood samples. Statistical analyses were conducted using GraphPad Prism v10 and other software. Variants of F2RL1 gene, specifically rs1529505 (OR= 1.65, 95%CI: 1.26 to 2.14, P =0.0002) and rs2272991 (OR= 1.89, 95%CI: 1.32 to 2.71, P =0.0005), were associated with asthma predisposition. Genetic variants rs1529505 and rs631465 were associated with susceptibility and clinical severity in Chinese patients with asthma. The mutant genotypes of rs2272991 and rs1529505 correlated with elevated PAR-2 mRNA expression levels. Haplotype distribution did not reveal significant differences between asthma cases and controls, nor among severity groups. This study elucidated the influence of F2RL1 polymorphisms on PAR-2 mRNA expression and their impact on asthma pathogenesis within the Chinese population. Further research involving diverse populations is necessary to validate these findings.