Epithelial cells are immune sensors and mediators that constitute the first line of defense against infections. Using the epididymis, a model for studying tubular organs, we uncovered a novel and unexpected role for professional proton-secreting 'clear cells' in sperm maturation and immune defense. The epididymal epithelium participates in the maturation of spermatozoa via the establishment of an acidic milieu and transfer of proteins to sperm cells, a poorly characterized process. We show that proton-secreting clear cells express mRNA transcripts and proteins that are acquired by maturing sperm, and that they establish close interactions with luminal spermatozoa via newly described 'nanotubes'. Mechanistic studies show that injection of bacterial antigens in vivo induces chemokine expression in clear cells, followed by macrophage recruitment into the organ. Injection of an inflammatory intermediate mediator (IFN-γ) increased Cxcl10 expression in clear cells, revealing their participation as sensors and mediators of inflammation. The functional diversity adopted by clear cells might represent a generalized phenomenon by which similar epithelial cells decode signals, communicate with neighbors and mediate mucosal immunity, depending on their precise location within an organ.

中文翻译：

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质子分泌上皮细胞在精子成熟和粘膜免疫中的新作用。

上皮细胞是免疫传感器和介体，是抵抗感染的第一道防线。使用附睾，一种研究肾小管器官的模型，我们发现了专业的质子分泌“透明细胞”在精子成熟和免疫防御中的新颖而出乎意料的作用。附睾上皮通过建立酸性环境并将蛋白质转移到精子细胞中来参与精子的成熟，这是一个特征较差的过程。我们表明，质子分泌的透明细胞表达通过成熟精子获得的mRNA转录本和蛋白质，并且它们通过新描述的“纳米管”与管腔精子建立紧密的相互作用。机理研究表明，体内注射细菌抗原可诱导透明细胞中趋化因子的表达，然后将巨噬细胞募集到器官中。注射炎性中间介质（IFN-γ）可以增加透明细胞中Cxcl10的表达，表明它们参与了炎症的传感器和介质。透明细胞所采用的功能多样性可能代表了一种普遍现象，通过这种现象，类似的上皮细胞可以解码信号，与邻居沟通并介导粘膜免疫，这取决于它们在器官中的精确位置。