Effect of fatty acids on herbicide transport across Caco-2 cell monolayers

Investigating the Bioaccessibility and Bioavailability of Cadmium in a Cooked Rice Food Matrix by Using an 11-Day Rapid Caco-2/HT-29 Co-culture Cell Model Combined with an In Vitro Digestion Model

Investigating the bioaccessibility and bioavailability of Cd based on real contaminated cooked rice matrixes helps establish an accurate risk assessment method and effectively reduce the digestion and absorption of Cd. An 11-day in vitro rapid Caco-2/HT-29 co-culture cell model was used to establish and evaluate the simulation of the absorption and transport of Cd in the small intestine with a 70:30 Caco-2/HT-29 co-culture ratio and 1.0 mmol L^-1 butyric acid as a differentiation inducer. The bioaccessibility and bioavailability of Cd in cooked rice were studied using the cell model combined with an in vitro digestion model. The bioaccessibility of Cd of each of the three cooked rice samples was significantly higher in the gastric phase (59.04-80.23%) than in the gastrointestinal phase (37.14-52.93%). Despite the extension of the digestion time of the gastrointestinal phase, no significant difference was found among the time points. Results demonstrated that the amount of undigested residue, not the level of Cd contamination, significantly contributed to the bioaccessibility of Cd, which was affected by pH or ion. The absorption rate of Cd (25.08% ± 3.05%) was greater than the values obtained using the pure Caco-2 cell models. The bioavailability of Cd (8.29% ± 1.95%) was almost similar to that of Zn²⁺ (6.66% ± 1.41%) in the cooked rice matrix, indicating that the intestinal epithelium expressed a strong absorptive capacity of Cd during the absorption of essential metallic elements. The 11-day rapid Caco-2/HT-29 co-culture cell model combined with the in vitro digestion model was an efficient tool for studying the bioaccessibility and bioavailability of Cd or other substances in a food matrix to further investigate mechanistic steps and screen a broad set of food matrix factors.

Ethylene bisdithiocarbamate pesticides Maneb and Mancozeb cause metal overload in human colon cells

Previous studies in our laboratory have shown that ethylene bisdithiocarbamate (EBDC) fungicides Maneb and Mancozeb are equipotent gastrointestinal toxicants that produce cell loss and metal accumulation within HT-29 and Caco2 colon cells. Nabam, MnCl2, CuCl2 and ZnCl2 exposure produced no loss of viability up to 200 μM and increases in metal levels were noted but not to the same extent as Maneb and Mancozeb. EBDC exposure caused increases in copper levels (20-200 μM). Maneb and Mancozeb treatment also caused increases in manganese and zinc concentrations (20-200 μM). Nabam plus MnCl2 and Nabam and MnCl2 plus ZnCl2 caused decreases in viability and increases in metal levels comparable to Maneb and Mancozeb. Decreases in the ratio of reduced glutathione to glutathione disulfide were observed with Maneb and Mancozeb (20-200 μM). Maneb and Mancozeb treatment results in intracellular metal accumulation leading to the oxidative stress. The metal moiety and the organic portion of EBDCs contribute to toxicity.

Ethylene bisdithiocarbamate pesticides cause cytotoxicity in transformed and normal human colon cells

The effects of the fungicides Maneb, Mancozeb, and Zineb were investigated in transformed colon cells, HT-29, Caco2 and non-transformed cells, CCD-18Co. Significant decreases in viability were observed with Maneb and Mancozeb in HT-29 and CCD-18Co (80-260μM), and Caco2 cells (40-180μM). No significant decreases in viability were observed in all cell types up to 800μM with Zineb. MnCl(2) and ZnCl(2) exposure produced no loss of viability in all cell types up to 400μM. Light microscopy confirmed viability analysis. Lipid peroxidation was observed with Maneb and Mancozeb in cell types tested (60-200μM). Caspase 3/7, 8, and 9 activities were observed with Maneb and Mancozeb in cell types tested (40-200μM). Maneb and Mancozeb treated HT-29 and Caco2 cells demonstrated increases in manganese and zinc concentrations (20-200μM). The lack of toxicity observed with Zineb, MnCl(2), and ZnCl(2) suggests that both the metal moiety and the organic portion of these fungicides together contribute to toxicity.

Fatty acids increase paracellular absorption of aluminium across Caco-2 cell monolayers

Passive paracellular absorption, regulated by tight junctions (TJs), is the main route for absorption of poorly absorbed hydrophilic substances. Surface active substances, such as fatty acids, may enhance absorption of these substances by affecting the integrity of TJ and increasing the permeability. It has been suggested that aluminium (Al) absorption occurs mainly by the paracellular route. Herein, we investigated if physiologically relevant exposures of fully differentiated Caco-2 cell monolayers to oleic acid and docosahexaenoic acid (DHA), which are fatty acids common in food, increase absorption of Al and the paracellular marker mannitol. In an Al toxicity test, mannitol and Al absorption through Caco-2 cell monolayers were similarly modulated by Al concentrations between 1 and 30mM, suggesting that absorption of the two compounds occurred via the same pathways. Exposure of Caco-2 cell monolayers to non-toxic concentrations of Al (2mM) and (14)C-mannitol in fatty acid emulsions (15 and 30mM oleic acid, 5 and 10mM DHA) caused a decreased transepithelial electrical resistance (TEER). Concomitantly, fractional absorption of Al and mannitol, expressed as percentage of apical Al and mannitol retrieved at the basolateral side, increased with increasing dose of fatty acids. Transmission electron microscopy was applied to assess the effect of oleic acid on the morphology of TJ. It was shown that oleic acid caused a less structured morphology of TJ in Caco-2 cell monolayers. Taken together our findings indicate that fatty acids common in food increase the paracellular intestinal absorption of Al. These findings may influence future risk assessment of human Al exposure.