Identifying immune burden status and predictors via the non-classical type 2 inflammatory axis in allergic rhinitis

While the roles of classical type 2 (T2) inflammatory factors in allergic rhinitis (AR) have been well characterized, the roles of non-classical T2 inflammation factors are less explored. This study aimed to elucidate the roles and predictive significance of non-classical T2 inflammatory factors in AR.

AR-related datasets were retrieved from GEO for bioinformatics analysis. A total of 64 AR patients and 42 healthy controls were included. Non-classical T2 factors and T1 cytokines were measured by ELISAs. The SNOT-22 and VAS scores were used to evaluate the disease severity of AR. PCA-PAM clustering, MCA and correlation network analysis were performed to explore the inflammatory pattern and interactions of non-classical T2 factors, respectively. ROC curves were constructed to evaluate the predictive performance. All biomarkers were robustly standardized to healthy control medians and IQRs prior to PCA, MCA, and ROC analyses. Internal validation was performed via LOOCV, bootstrap resampling, and 10-fold cross-validation.

Serum ALOX15 and ratios of ALOX15, CLC, CST1, POSTN, TSLP, and IL-33 to T1 cytokines were significantly elevated in AR patients, with concordant upregulation of ALOX15 at transcript and protein levels in both nasal mucosa and serum. PAM clustering of PCA-derived T1/T2 biomarkers stratified AR patients into the low-immune-response type (LIR-AR, n = 40) and the high-immune-response type (HIR-AR, n = 24) endotypes. MCA identified CST1, POSTN, and CLC as the top discriminators, with IL-33 spatially separated from downstream effectors. CST1 levels and the ALOX15/IFN-γ ratios were correlated with the VAS scores for rhinorrhea and nasal itching, respectively. The ALOX15/TNF-α ratio exhibited good predictive accuracy for AR (AUC = 0.856 ± 0.106).

AR was characterized by T1/T2 imbalance, with elevated ALOX15 and increased T2/T1 ratios in both nasal mucosa and serum, suggesting ALOX15 as a potential biomarker. CST1, POSTN, and CLC were core variables distinguishing LIR-AR from HIR-AR and may be useful for immunotype differentiation. CST1 expression and the ALOX15/IFN-γ ratio correlated with rhinorrhea and nasal itching, respectively; however, these correlation-based findings require cautious interpretation regarding causality. The ALOX15/TNF-α ratio showed good diagnostic value for AR, with these exploratory findings requiring validation in larger independent cohorts and functional studies.