Tobin Julie D, Robinson Corie N, Luttrell-Williams Elliot S, Landry Greg M, McMartin Kenneth E
Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA 71130, USA.
Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA 71130, USA.
Toxicol Lett. 2023 Apr 15;379:48-55. doi: 10.1016/j.toxlet.2023.03.007. Epub 2023 Mar 22.
Diethylene glycol (DEG) mass poisonings have resulted from ingestion of adulterated pharmaceuticals, leading to proximal tubular necrosis and acute kidney injury. Diglycolic acid (DGA), one of the primary metabolites, accumulates greatly in kidney tissue and its direct administration results in toxicity identical to that in DEG-treated rats. DGA is a dicarboxylic acid, similar in structure to Krebs cycle intermediates such as succinate. Previous studies have shown that DGA is taken into kidney cells via the succinate-related dicarboxylate transporters. These studies have assessed whether the DGA that is taken up by primary cultures of human proximal tubule (HPT) cells is effluxed. In addition, a possible mechanism for efflux, via organic anion transporters (OATs) that exchange external organic anions for dicarboxylates inside the cell, was assessed using transformed cell lines that actively express OAT activities. When HPT cells were cultured on membrane inserts, then loaded with DGA and treated with the OAT4/5 substrate estrone sulfate or the OAT1/3 substrate para-aminohippurate, no DGA efflux was seen. A repeat of this experiment utilizing RPTEC/TERT1 cells with overexpressed OAT1 and OAT3 had similar results. In these cells, but not in HPT cells, co-incubation with succinate increased the uptake of PAH, confirming the presence of OAT activity in the RPTEC/TERT1 cells. Thus, despite OATs stimulation in cells with OAT activity, there was little to no efflux of DGA from the cells. This study concluded that DGA is poorly transported out of cells and that stimulation of OAT transporters is not a viable target for reducing DGA accumulation in cells.
摄入掺假药品导致了二甘醇（DEG）群体性中毒事件，进而引发近端肾小管坏死和急性肾损伤。二乙醇酸（DGA）是主要代谢产物之一，在肾组织中大量蓄积，直接给予DGA会导致与DEG处理的大鼠相同的毒性。DGA是一种二羧酸，其结构与琥珀酸等三羧酸循环中间体相似。先前的研究表明，DGA通过与琥珀酸相关的二羧酸转运体进入肾细胞。这些研究评估了人近端小管（HPT）细胞原代培养物摄取的DGA是否会流出。此外，利用主动表达OAT活性的转化细胞系，评估了一种可能的流出机制，即通过有机阴离子转运体（OATs）将细胞内的二羧酸盐与外部有机阴离子进行交换。当HPT细胞在膜插入物上培养，加载DGA并使用OAT4/5底物硫酸雌酮或OAT1/3底物对氨基马尿酸处理时，未观察到DGA流出。利用过表达OAT1和OAT3的RPTEC/TERT1细胞重复该实验，结果相似。在这些细胞中，但不在HPT细胞中，与琥珀酸共孵育会增加PAH的摄取，证实RPTEC/TERT1细胞中存在OAT活性。因此，尽管具有OAT活性的细胞中OATs受到刺激，但细胞中几乎没有DGA流出。本研究得出结论，DGA很难从细胞中转运出来，刺激OAT转运体不是减少细胞中DGA蓄积的可行靶点。
