Adolphe Merkle Institute, University of Fribourg, 1700 Fribourg, Switzerland.
International Iberian Nanotechnology Laboratory, Water Quality Group, 4715-330 Braga, Portugal.
Toxins (Basel). 2023 Jul 29;15(8):482. doi: 10.3390/toxins15080482.
The gastrointestinal tract is the main target of orally ingested nanoparticles (NPs) and at the same time is exposed to noxious substances, such as bacterial components. We investigated the interaction of 59 nm silica (SiO) NPs with differentiated Caco-2 intestinal epithelial cells in the presence of cholera toxin subunit B (CTxB) and compared the effects to J774A.1 macrophages. CTxB can affect cellular functions and modulate endocytosis via binding to the monosialoganglioside (GM1) receptor, expressed on both cell lines. After stimulating macrophages with CTxB, we observed notable changes in the membrane structure but not in Caco-2 cells, and no secretion of the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) was detected. Cells were then exposed to 59 nm SiO NPs and CtxB sequentially and simultaneously, resulting in a high NP uptake in J774A.1 cells, but no uptake in Caco-2 cells was detected. Flow cytometry analysis revealed that the exposure of J774A.1 cells to CTxB resulted in a significant reduction in the uptake of SiO NPs. In contrast, the uptake of NPs by highly selective Caco-2 cells remained unaffected following CTxB exposure. Based on colocalization studies, CTxB and NPs might enter cells via shared endocytic pathways, followed by their sorting into different intracellular compartments. Our findings provide new insights into CTxB's function of modulating SiO NP uptake in phagocytic but not in differentiated intestine cells.
胃肠道是口服纳米颗粒（NPs）的主要靶标，同时也会暴露于有害物质，如细菌成分。我们研究了 59nm 二氧化硅（SiO）NPs 在霍乱毒素亚单位 B（CTxB）存在下与分化的 Caco-2 肠上皮细胞的相互作用，并将其与 J774A.1 巨噬细胞进行了比较。CTxB 可以通过与两种细胞系上表达的单唾液酸神经节苷脂（GM1）受体结合来影响细胞功能并调节内吞作用。用 CTxB 刺激巨噬细胞后，我们观察到其细胞膜结构发生明显变化，但 Caco-2 细胞没有发生变化，也没有检测到促炎细胞因子肿瘤坏死因子-α（TNF-α）的分泌。然后，细胞依次和同时暴露于 59nm SiO NPs 和 CTxB，导致 J774A.1 细胞中 NP 的摄取量很高，但 Caco-2 细胞中未检测到摄取。流式细胞术分析显示，J774A.1 细胞暴露于 CTxB 会导致 SiO NPs 的摄取显著减少。相比之下，CTxB 暴露后，高度选择性的 Caco-2 细胞对 NPs 的摄取不受影响。基于共定位研究，CTxB 和 NPs 可能通过共享的内吞途径进入细胞，然后被分拣到不同的细胞内隔室。我们的研究结果提供了关于 CTxB 调节吞噬细胞而非分化肠道细胞中 SiO NP 摄取的新见解。
