Clec4a4+ and Clec4a4- eosinophils in the small intestine. Clec4a4+ and Clec4a4- eosinophils in the small intestine

Eosinophils contribute to parasitic helminths- and allergens-induced type 2 immune responses. Although the gastrointestinal tract harbors a substantial number of eosinophils, the pathophysiological roles of intestinal eosinophils remain unclear. Here we identify a novel subset of eosinophil that expresses a repertoire of inhibitory molecules, including Clec4a4 and PD-L1. These Clec4a4+ leukocytes are blood-derived and exclusively present in the small intestine. Accordingly, this subset acquires imprinted features by the instruction of AHR signaling, which modulates immune responses to establish gut homeostasis. Selective depletion of AHR in eosinophils leads to a marked reduction of Clec4a4+PD-L1+ eosinophils and enhances the worm clearance accompanied by an increased type 2 immune response. Our findings may open new therapeutic avenues on primary eosinophilic gastrointestinal disorders. Overall design: 1. Profile the gene expression in sorted mCherry+ and mCherry- eosinophils from Clec4a4-mCherry reporter mice. 2. Profile the gene expression from sorted A. WT Clec4a4+ eosinophils, B. WT Clec4a4- eosinophils, and C. Ahr KO Clec4a4- eosinophils.

嗜酸性粒细胞（Eosinophils）参与寄生性蠕虫与变应原诱导的2型免疫应答。尽管胃肠道内存在大量嗜酸性粒细胞，但肠道嗜酸性粒细胞的病理生理作用仍未明确。本研究鉴定出一类新型嗜酸性粒细胞亚群，其表达一组抑制性分子，包括Clec4a4与PD-L1。这类Clec4a4⁺白细胞源自血液，且仅分布于小肠。该亚群通过芳香烃受体（AHR）信号通路的调控获得印记特征，进而调节免疫应答以维持肠道稳态。选择性敲除嗜酸性粒细胞中的AHR，可显著减少Clec4a4⁺PD-L1⁺嗜酸性粒细胞亚群，并伴随2型免疫应答增强，从而提升蠕虫清除效率。本研究结果可为原发性嗜酸性粒细胞性胃肠道疾病开辟全新的治疗途径。整体实验设计如下：1. 对从Clec4a4-mCherry报告基因小鼠中分选得到的mCherry⁺与mCherry⁻嗜酸性粒细胞进行基因表达谱分析；2. 对分选得到的样本进行基因表达谱分析：A. 野生型（WT）Clec4a4⁺嗜酸性粒细胞、B. 野生型（WT）Clec4a4⁻嗜酸性粒细胞以及C. Ahr敲除（Ahr KO）Clec4a4⁻嗜酸性粒细胞。