This study aimed to investigate the transportation and absorption mechanism of lanthanum carbonate [La2(CO3)3] through the gastrointestinal (GI) tract using in vitro and in vivo models. The results demonstrated that La2(CO3)3 can be dissolved in gastric fluids and precipitated into lanthanum phosphate as the main transformed specie in intestinal fluid. Using Caco-2 cell monoculture and Caco-2/Raji B cell coculture models to simulate the intestinal epithelium and microfold (M) cells, it was found that the amount of lanthanum transported in Caco-2/Raji B coculture model was significantly higher than that in Caco-2 monoculture model (about 50 times higher), indicating that M cells play an important role in the intestinal absorption of La2(CO3)3. Furthermore, oral administration of La2(CO3)3 to Balb/c mice demonstrated that lanthanum can be absorbed by both Peyer's patches (PPs) and non-PPs intestinal epithelium, with a higher amount of absorption in the PPs per unit weight. This finding further confirmed that the lanthanum absorption in GI tract could be mainly due to the contribution of M cells. Meanwhile, the administration of La2(CO3)3 caused a marked lanthanum accumulation in liver, accompanied by the activation of Kupffer cells. This study clarified how La2(CO3)3 is absorbed through the GI tract to enter the body and would be helpful to evaluate its potential biological consequences of accumulation in human beings.

中文翻译：

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碳酸镧是一种有效的选择性磷酸盐结合剂，主要通过胃肠道中的 M 细胞转运和吸收。

本研究旨在利用体外和体内模型研究碳酸镧 [La2(CO3)3] 通过胃肠道 (GI) 的运输和吸收机制。结果表明，La2(CO3)3可以溶解在胃液中，并在肠液中沉淀为磷酸镧，为主要转化物质。利用Caco-2细胞单一培养和Caco-2/Raji B细胞共培养模型模拟肠上皮和微褶皱（M）细胞，发现Caco-2/Raji B共培养模型中的镧转运量显着高于在 Caco-2 单一培养模型中（约高出 50 倍），表明 M 细胞在 La2(CO3)3 的肠道吸收中发挥着重要作用。此外，Balb/c小鼠口服La2(CO3)3表明，镧可以被派尔氏淋巴结(PPs)和非PPs肠上皮吸收，单位重量PPs的吸收量更高。这一发现进一步证实了胃肠道对镧的吸收可能主要是由于M细胞的贡献。同时，La2(CO3)3的施用导致肝脏中明显的镧积累，并伴随库普弗细胞的活化。这项研究阐明了La2(CO3)3如何通过胃肠道吸收进入人体，有助于评估其在人类体内积累的潜在生物学后果。这一发现进一步证实了胃肠道对镧的吸收可能主要是由于M细胞的贡献。同时，La2(CO3)3的施用导致肝脏中明显的镧积累，并伴随库普弗细胞的活化。这项研究阐明了La2(CO3)3如何通过胃肠道吸收进入人体，有助于评估其在人类体内积累的潜在生物学后果。这一发现进一步证实了胃肠道对镧的吸收可能主要是由于M细胞的贡献。同时，La2(CO3)3的施用导致肝脏中明显的镧积累，并伴随库普弗细胞的活化。这项研究阐明了La2(CO3)3如何通过胃肠道吸收进入人体，有助于评估其在人类体内积累的潜在生物学后果。