Intercellular communication is critical for organismal homeostasis and defects can contribute to human disease states. Polarized epithelial cells execute distinct signaling agendas via apical and basolateral surfaces to communicate with different cell types. Small extracellular vesicles (sEVs), including exosomes and small microvesicles, represent an understudied form of intercellular communication in polarized cells. Human cholangiocytes, epithelial cells lining bile ducts, were cultured as polarized epithelia in a transwell system as a model with which to study polarized sEV communication. Characterization of isolated apically and basolaterally released EVs revealed enrichment in sEVs. However, differences in apical and basolateral sEV composition and numbers were observed. Genetic or pharmacological perturbation of cellular machinery involved in the biogenesis of intralumenal vesicles at endosomes (the source of exosomes) revealed general and domain-specific effects on sEV biogenesis/release. Additionally, analyses of signaling revealed distinct profiles of activation depending upon sEV population, target cell, and the function of the Endosomal Sorting Complex Required for Transport (ESCRT)-associated factor ALIX within the donor cells. These results support the conclusion that polarized cholangiocytes release distinct sEVs pools to mediate communication via their apical and basolateral domains and suggest that defective ESCRT function may contribute to disease states through altered sEV signaling.

细胞间通讯对于有机体稳态至关重要，缺陷可能导致人类疾病状态。极化上皮细胞通过顶端和基底外侧表面执行不同的信号传递议程，以与不同的细胞类型进行通信。小细胞外囊泡 (sEV)，包括外泌体和小微囊泡，代表了极化细胞中一种未被充分研究的细胞间通讯形式。人类胆管细胞（胆管内衬的上皮细胞）在 transwell 系统中培养为极化上皮细胞，作为研究极化 sEV 通信的模型。分离的顶端和基底外侧释放的 EV 的表征揭示了 sEV 的富集。然而，观察到顶端和基底外侧 sEV 组成和数量的差异。在内体（外泌体的来源）处腔内囊泡生物发生所涉及的细胞机制的遗传或药理学扰动揭示了对 sEV 生物发生/释放的一般和特定领域的影响。此外，信号分析揭示了不同的激活谱，这取决于 sEV 群体、靶细胞和供体细胞内转运所需的内体分选复合物 (ESCRT) 相关因子 ALIX 的功能。这些结果支持极化胆管细胞释放不同的 sEV 池以通过其顶端和基底外侧域介导交流的结论，并表明有缺陷的 ESCRT 功能可能通过改变 sEV 信号传导导致疾病状态。