The role of CCR3 via IL-33/CD34 palmitoylation in allergic rhinitis: A comprehensive analysis.

Background

The post-translational modification of chemokine receptors plays a vital role in immune regulation, yet the specific role of CCR3 palmitoylation in allergic rhinitis (AR) remains elusive.

Objective

This study aims to investigate the bioinformatic signatures of AR and elucidate the underlying molecular mechanisms of CCR3 palmitoylation in AR.

Methods

An integrated bioinformatics approach, utilizing seven machine learning algorithms and Gene Set Enrichment Analysis (GSEA), was employed to identify key transcriptomic signatures and pathways in AR. In vivo, an allergen-induced AR model was established using wild-type and CCR3 knockout mice to evaluate histopathology, Th2 cytokine profiles, and CD34+ cell infiltration. The acyl-biotin exchange (ABE) assay was utilized to quantify CCR3 palmitoylation levels. In vitro, primary bone marrow-derived eosinophils (BM-Eos) were utilized to explore the upstream drivers of CCR3 palmitoylation. siRNA knockdown, site-directed mutagenesis, and genetic rescue experiments were conducted to confirm the specific palmitoyltransferases and modification sites.

Results

Bioinformatics screening identified lipid metabolism/palmitoylation and the IL-33/CD34 axis as key pathways in AR. In vivo experiments confirmed elevated CCR3 palmitoylation in AR mice, while CCR3 KO significantly alleviated Th2 inflammation, CD34+ cell recruitment, and nasal symptoms. Mechanistically, in vitro assays revealed that the IL-33/ST2 axis directly drives CCR3 palmitoylation, predominantly mediated by the palmitoyltransferase ZDHHC-21. Mutagenesis confirmed that Cys298 and Cys299 are the critical sites for CCR3 palmitoylation. Crucially, functional rescue experiments demonstrated that palmitoylation at Cys298/299 is strictly required for IL-33-mediated release of downstream pro-inflammatory mediators (IL-13 and CCL-2) in eosinophils.

Conclusion

This study demonstrates that the specific palmitoylation of CCR3 at Cys298/299, catalyzed by ZDHHC-21 in response to IL-33 signaling, is a critical molecular event driving eosinophilic inflammation in AR. Although targeting this lipid modification presents a novel therapeutic strategy, the complex interplay between CCR3 palmitoylation and other nasal microenvironmental factors, as well as its reversible de-palmitoylation dynamics, remain to be fully elucidated in future studies.