The present study was designed to investigate thein vivobiological processes of multivesicular bodies (MVBs) and exosomes in mitochondria-rich cells (MRCs), goblet cells (GCs), and absorptive cells (ACs) in turtle intestines during hibernation. The exosome markers, cluster of differentiation 63 (CD63) and tumor susceptibility gene 101 (TSG101), were positively expressed in intestinal villi during turtle hibernation. The distribution and formation processes of MVBs and exosomes in turtle MRCs, GCs, and ACs were further confirmed by transmission electron microscopy. During hibernation, abundantly secreted early endosomes (ees) were localized in the luminal and basal cytoplasm of the MRCs and ACs, and late endosomes (les) were dispersed with the supranuclear parts of the MRCs and ACs. Many “heterogeneous” MVBs were identified throughout the cytoplasm of the MRCs and ACs. Interestingly, the ees, les, and MVBs were detected in the cytoplasm of the GCs during hibernation; however, they were absent during nonhibernation. Furthermore, the exocytosis pathways of exosomes and autophagic vacuoles were observed in the MRCs, GCs, and ACs during hibernation. In addition, the number of different MVBs with intraluminal vesicles (ILVs) and heterogeneous endosome–MVB–exosome complexes was significantly increased in the MRCs, GCs, and ACs during hibernation. All these findings indicate that intestinal epithelial cells potentially perform a role in the secretion of MVBs and exosomes, which are essential for mucosal immunity, during hibernation.

中文翻译：

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冬眠期间龟肠上皮细胞的体内多泡体和外泌体分泌

本研究旨在调查体内冬眠期间乌龟肠道中富含线粒体的细胞 (MRCs)、杯状细胞 (GCs) 和吸收细胞 (ACs) 中多泡体 (MVB) 和外泌体的生物学过程。外泌体标志物，分化簇 63 (CD63) 和肿瘤易感基因 101 (TSG101)，在乌龟冬眠期间在肠绒毛中呈阳性表达。通过透射电子显微镜进一步证实了 MVBs 和外泌体在龟 MRC、GC 和 ACs 中的分布和形成过程。在冬眠期间，大量分泌的早期内体 (ees) 位于 MRC 和 AC 的腔内和基底细胞质中，晚期内体 (les) 与 MRC 和 AC 的核上部分一起分散。在 MRC 和 AC 的整个细胞质中鉴定出许多“异质”MVB。有趣的是， ees, les, 并且在冬眠期间在GC的细胞质中检测到MVB；但是，它们在非休眠期间不存在。此外，在冬眠期间，在 MRC、GC 和 AC 中观察到外泌体和自噬泡的胞吐途径。此外，具有腔内囊泡 (ILV) 和异质内体的不同 MVB 的数量–MVB–在冬眠期间，MRC、GC 和 AC 中的外泌体复合物显着增加。所有这些发现表明，在冬眠期间，肠上皮细胞可能在 MVB 和外泌体的分泌中发挥作用，这对黏膜免疫至关重要。