Serum Soluble Fibrinogen-Like Protein 2 Estimates Increased T-Helper 2 Cytokine, Elevated Disease Severity, and Unfavorable Outcomes in Allergic Rhinitis Patients

Objective: Soluble fibrinogen-like protein 2 (sFGL2) may be involved in the pathology and progression of allergic rhinitis (AR) through regulating T-helper (Th)2 cell response. This study aimed to explore the ability of sFGL2 to estimate outcomes in AR patients. Methods: sFGL2 was detected in the serum sample of 119 AR patients at baseline and 20 healthy controls (HCs) after enrollment by enzyme-linked immunosorbent assay. In AR patients, disease severity was assessed at baseline as well as 4 weeks (W4) and 8 weeks (W8) after enrollment by the total nasal symptom score (TNSS). Results: sFGL2 was higher in AR patients than HCs [median (interquartile range): 100.0 (70.0-154.0) vs 47.0 (31.5-78.5) ng/mL] ( P < .001). In AR patients, sFGL2 was positively correlated with TNSS score ( P = .002), itching score ( P = .037), sneezing score ( P = .012), and interleukin (IL)-4 ( P = .006) at baseline. TNSS score declined from baseline to W8 in AR patients ( P < .001). To further explore the association between sFGL2 levels and treatment outcomes, we compared the sFGL2 levels between patients with TNSS scores at W4 or W8 >4 and those with TNSS scores at W4 or W8 ≤4. It was found that sFGL2 was only increased in AR patients with a TNSS score at W4 >4 versus those with a TNSS score at W4 ≤4 ( P = .012). Conclusion: Serum sFGL2 is increased in AR patients, and its high level estimates an increased Th2 cytokine and disease severity as well as poor outcomes.