Tubular changes contribute to the development of renal pathologies in DKD, including interstitial fibrosis. It is unclear how tubular cells relay signals to interstitial fibroblasts. Recently, exosomes have been recognized as crucial mediators of intercellular communication. We hypothesized that exosomes secreted from tubular cells may stimulate fibroblasts for interstitial fibrosis in DKD. In this study, we isolated exosomes from the renal cortex of DKD mice and high glucose treated mouse proximal tubular cells. Compared to non-diabetic mice, exosome secretion in kidney tissues decreased in DKD mice. Likewise, high glucose incubation reduced exosome secretion in mouse kidney proximal tubular BUMPT cells. To study the effect of tubular cell exosomes on fibroblasts, the exosomes from BUMPT cells were added to renal fibroblast NRK-49F cell cultures. Notably, the exosomes from high glucose conditioned BUMPT cells (HG-Exo) induced higher proliferation, significant morphologic change, and substantial production of fibronectin, a-SMA and collagen I in fibroblasts. Proteomics analysis was further performed to profile the proteins within tubular cell exosomes. Interestingly, twenty-two proteins were found differentially expressed between HG-Exo and NG-Exo. Cytoscape analysis suggested two PPI networks in these exosomal differentially expressed proteins (DEPs). Gene expression analysis via Nephroseq showed a correlation of Eno1 expression with DKD clinical manifestation. In conclusion, DKD is associated with a decrease in exosome secretion in renal tubular cells. The exosomes from high glucose conditioned tubular cells may regulate the proliferation and activation of fibroblasts, contributing to the paracrine signaling mechanism responsible for the pathological onset of renal interstitial fibrosis in DKD.

中文翻译：

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糖尿病肾病中肾小管外泌体的分泌减少和促纤维化活性。

肾小管变化有助于 DKD 肾脏病变的发展，包括间质纤维化。目前尚不清楚肾小管细胞如何将信号传递给间质成纤维细胞。最近，外泌体被认为是细胞间通讯的关键介质。我们假设肾小管细胞分泌的外泌体可能会刺激成纤维细胞发生 DKD 间质纤维化。在这项研究中，我们从 DKD 小鼠的肾皮质和高糖处理的小鼠近端肾小管细胞中分离出外泌体。与非糖尿病小鼠相比，DKD 小鼠肾组织中的外泌体分泌减少。同样，高葡萄糖孵育减少了小鼠肾近端肾小管 BUMPT 细胞的外泌体分泌。为了研究肾小管细胞外泌体对成纤维细胞的影响，将来自 BUMPT 细胞的外泌体添加到肾成纤维细胞 NRK-49F 细胞培养物中。值得注意的是，来自高糖条件下的 BUMPT 细胞（HG-Exo）的外泌体在成纤维细胞中诱导了更高的增殖、显着的形态变化以及纤连蛋白、a-SMA 和胶原蛋白 I 的大量产生。进一步进行蛋白质组学分析以分析管状细胞外泌体中的蛋白质。有趣的是，发现 22 种蛋白质在 HG-Exo 和 NG-Exo 之间差异表达。Cytoscape 分析表明这些外泌体差异表达蛋白 (DEP) 中有两个 PPI 网络。通过 Nephroseq 进行的基因表达分析显示 Eno1 表达与 DKD 临床表现相关。总之，DKD 与肾小管细胞外泌体分泌减少有关。来自高糖条件下肾小管细胞的外泌体可以调节成纤维细胞的增殖和活化，