Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Avenida Agustín Escardino No. 7, 46980 Paterna, Valencia, Spain.
Chem Res Toxicol. 2012 Nov 19;25(11):2402-11. doi: 10.1021/tx300385y. Epub 2012 Oct 4.
This study evaluates the metabolism of inorganic arsenic (iAs) [As(III) and As(V)] in human intestinal cells as a function of cell type, differentiation stage, type of support used for cell growth, and exposure time. Additionally, mRNA expression of arsenic (+3 oxidation state) methyltransferase (AS3MT) was evaluated. For this purpose, Caco-2 (absorptive type) and HT29-MTX (goblet type) cells were exposed at various stages of differentiation (5, 15, and 21 days post-seeding) with different concentrations of As(III) and As(V) (1 and 10 μM) and exposure times (24, 48, and 72 h), using multiwell plates or Transwells. The results show that both cell lines express AS3MT at all stages of differentiation and in all culture conditions. Caco-2 cells are capable of metabolizing iAs, As(III) metabolism being greater than that observed for As(V). Metabolism depends on the stage of differentiation, reaching 36% after 48 h of exposure of differentiated cells (15 days post-seeding), with the monomethylated species as the major metabolite. Analysis of the cell interior shows that the metabolites are present predominantly in trivalent form. The type of support is also an important factor, metabolism being greater in multiwell plates than in Transwells (36 ± 6% vs 11 ± 3%). Neither monomethylated arsenic species (MMA) nor dimethylated arsenic species (DMA) are detected in HT29-MTX cells after exposure to iAs, possibly because most of the iAs is retained in the mucus layer and does not internalize. These results show that the intestine is an organ that may take part in presystemic metabolism of iAs. Moreover, the transformation of iAs into more toxic species indicates the need to study the effects of this species on the intestinal epithelium.
本研究评估了无机砷（iAs）[As(III)和 As(V)]在人类肠道细胞中的代谢情况，研究内容涉及细胞类型、分化阶段、用于细胞生长的支撑类型和暴露时间等多个方面。此外，还评估了砷 (+3 氧化态) 甲基转移酶 (AS3MT) 的 mRNA 表达情况。为此，本研究使用 Caco-2（吸收型）和 HT29-MTX（杯状细胞型）细胞，在不同的分化阶段（接种后第 5、15 和 21 天），采用不同浓度的 As(III) 和 As(V)（1 和 10 μM）和暴露时间（24、48 和 72 h），在多孔板或 Transwell 中进行暴露实验。结果表明，两种细胞系在所有分化阶段和所有培养条件下均表达 AS3MT。Caco-2 细胞能够代谢 iAs，As(III) 的代谢速度大于 As(V)。代谢速度取决于分化阶段，分化细胞（接种后第 15 天）暴露 48 小时后达到 36%，主要代谢产物为单甲基化砷。细胞内分析表明，代谢产物主要以三价形式存在。支撑类型也是一个重要因素，多孔板中的代谢速度大于 Transwell（36 ± 6% vs 11 ± 3%）。在暴露于 iAs 后，HT29-MTX 细胞中未检测到单甲基化砷物种 (MMA) 或二甲基化砷物种 (DMA)，这可能是因为大部分 iAs 被保留在黏液层中而没有内化。这些结果表明，肠道是可能参与 iAs 预系统性代谢的器官。此外，iAs 向更具毒性的物种的转化表明需要研究该物种对肠道上皮的影响。
