Meng-Yi Wei, Zhi-Qiang Zhang, Hao Li, Ying Zhang, Wen-Jing Lei, Xin-Hua Zhu
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.
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.