Investigation of selenium and selenium species in Cardamine violifolia using in vitro digestion coupled with a Caco-2 cell monolayer model

Inadequate Se intake can enhance vulnerability to certain health risks, with supplementation lessening these risks. This study investigated the bioavailability of Se and Se species in five Se compounds and in Se-rich Cardamine violifolia using in vitro digestion coupled with a Caco-2 cell monolayer model, which enabled the study of Se transport and uptake. Translocation results showed that SeCys2 and MeSeCys had high translocation rates in C. violifolia leaves (CVLs). The uptake rate of organic Se increased with time, and MeSeCys exhibited a higher uptake rate than that for SeCys2 and SeMet. The translocation mechanisms of SeMet, Se(IV), and Se(VI) were passive transport, whereas those of SeCys2 and MeSeCys were active transport. The bioavailability of organic Se was higher than that of inorganic Se, with a total Se bioavailability in CVLs of 49.11 %. This study would provide a theoretical basis for the application of C. violifolia in the functional food.

Characterization of the intestinal transport mechanism of polystyrene microplastics (MPs) and the potential inhibitory effect of green tea extracts on MPs intestinal absorption

The aims of the current study included characterizing the intestinal transport mechanism of polystyrene microplastics (MPs) with different charges and sizes in the intestinal epithelial cell model and determining the inhibitory effect of green tea extracts (GTEs) on the intestinal absorption of MPs in Caco-2 cells. The smaller sizes, which included diameters of 0.2 μm, of amine-modified MPs compared to either larger size (1 μm diameter, or carboxylate-MPs (0.2 and 1 μm diameter) significantly lowered the cell viability of caco-2 cells that were measured by MTT assay (p < 0.05). The transported amount (particles/mL of the cell media) of amine-modified MPs by the Caco-2 cell, was not dependent according to the concentrations, energy, or temperature, but it was higher than the carboxylate-modified MPs. The co-treatment of GTEs with the amine-modified MPs inhibited Caco-2 cell cytotoxicity as well as reduced the production of intracellular reactive oxygen species (ROS) in HepG2 generated by the exposure of amine-modified MPs. The GTEs co-treatment also increased trans-epithelial electrical resistances (TEER) and reduced the transportation of Lucifer Yellow via the Caco-2 monolayer compared to only the amine-modified MPs exposure. The GTEs treatment led to a decrease in the number of amine-modified MPs transported to the basal side of the Caco-2 monolayer. The results from our study suggest that the consumption of GTEs could enhance the intestinal barrier function by recovering intestinal epithelial cell damage induced by MPs, which resulted in a decrease of the intestinal absorption of MPs.

Use of human Caco-2 cells and HPAE-PAD for α-glucosidase assay

To measure α-glucosidase activity, rat intestinal acetone powder is commonly used as a source of α-glucosidase, and the mutarotase-glucose oxidase (GOD) methods commonly used to quantitate glucose produced by enzymatic hydrolysis of the substrates. In this study, we compared human Caco-2 cell extracts with rat intestinal acetone powder extracts. We also compared high-performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD) with the mutarotase-GOD method. The sensitivity of HPAE-PAD was higher than that of mutarotase-GOD. The glucose concentration quantified by HPAE-PAD was similar to that quantified using the mutarotase-GOD method. In the maltase reaction, 1-deoxynojirimycin (1-DNJ) exerted a more potent inhibitory effect on human enzymes than on rat enzymes. This order was reversed during the sucrase reaction. These results suggested that the combined use of Caco-2 cell extracts and HPAE-PAD is advantageous for use in α-glucosidase-related basic research.

Changes in phenolic profile and anti-inflammatory activity of Baccharis beebread during gastrointestinal digestion/intestinal permeability in vitro

Knowledge about the fate of beebread bioactive compounds throughout the human gastrointestinal tract are scarce. The present study aimed at assessing the effects of gastrointestinal digestion followed by intestinal permeability in vitro on phenolic profile and anti-inflammatory activity of Baccharis beebread. Palynological analysis confirmed the beebread is predominantly composed by pollen grains from Baccharis species, which are endemic in south and southeast Brazil. Flavonols and phenylamides were found in beebread hydroalcoholic extract by HPLC-ESI-QTOF-MS analysis. Moreover, simulated digestion lead to compounds' breakage, releasing both aglycones from glycosylated flavonols and p-coumaric acid, but not caffeic acid from phenylamides. Only spermidines crossed the Caco-2 cell monolayer, possibly due to spermine oxidation. Free p-coumaric acid was released after digestion, and epithelial transport. Concomitantly, NF-κΒ activation and TNF-α level was decreased by beebread even after Caco-2 transport, which indicates spermidines conjugated with p-coumaric acid may be bioavailable compounds with anti-inflammatory activity.

Tuning Caco-2 permeability by cocrystallization: Insights from molecular dynamics simulation

Emerging evidence suggests that intestinal permeability can be potentially enhanced through cocrystallization. However, a mechanism for this effect remains to be established. In this study, we first demonstrate the enhancement in intestinal permeability, evaluated by the Caco-2 cell permeability assay, of acetazolamide (ACZ) in the presence of a conformer, p-aminobenzoic acid (PABA), delivered in the form of a 1:1 cocrystal. The binding strength of ACZ and PABA with the Pgp efflux transporter, either alone or as a mixture, was calculated using molecular dynamics simulation. Results show that PABA weakens the binding of ACZ with Pgp, which leads to a lower efflux ratio and elevated permeability of ACZ. This work provides molecular-level insights into a potentially effective strategy to improve the intestinal permeability of drugs. If the same cocrystal also exhibits higher solubility, oral bioavailability of BCS IV drugs can likely be improved by forming a cocrystal with a Pgp inhibitor.

Transport and interaction mechanism of four pesticide residues from Chaenomeles speciosa across Caco-2 cells

The presence of multiple pesticide residues in agricultural production highlights the need for studying mixture interaction during transepithelial transport. This study applied the Caco-2 cell model to investigate the interaction of four pesticide residues (carbendazim, epoxiconazole, phoxim, and chlorpyrifos) in Chaenomeles speciosa during transepithelial transport. Results demonstrated that co-treatment with pesticide mixtures generally increased the cumulative transport amount of carbendazim and epoxiconazole by 0.32-1.60 times and 0.32-0.98 times, respectively, compared to individual treatments. Notably, the combination of carbendazim and epoxiconazole displayed a significant synergistic effect. The use of transporter inhibitors and molecular docking analysis provided insights into the interaction mechanism, suggesting that the competitive inhibition of MRP2 and/or BCRP binding via π-bonds contributed to the inhibition of BL-to-AP efflux and a significant increase in AP-to-BL influx of carbendazim and epoxiconazole. The results are of great theoretical significance and practical value for risk assessment of multiple pesticide residues in agricultural products.

Characteristics and Absorption Rate of Whey Protein Hydrolysates Prepared Using Flavourzyme after Treatment with Alcalase and Protamex

The purpose of this study was to evaluate the physicochemical properties of whey protein hydrolysate and determine changes in absorption rate due to enzymatic hydrolysis. The molecular weight distribution analysis of whey protein concentrate (WPC) and low-molecule whey protein hydrolysate (LMWPH) using the Superdex G-75 column revealed that LMWPH is composed of peptides smaller than those in WPC. Fourier-transform infrared spectroscopy indicated differences in peak positions between WPC and LMWPH, suggesting hydrolysis-mediated changes in secondary structures. Moreover, LMWPH exhibited higher thermal stability and faster intestinal permeation than WPC. Additionally, oral LMWPH administration increased serum protein content at 20 min, whereas WPC gradually increased serum protein content after 40 min. Although the total amount of WPC and LMWPH absorption was similar, LMWPH absorption rate was higher. Collectively, LMWPH, a hydrolysate of WPC, has distinct physicochemical properties and enhanced absorptive characteristics. Taken together, LMWPH is composed of low-molecular-weight peptides with low antigenicity and has improved absorption compared to WPC. Therefore, LMWPH can be used as a protein source with high bioavailability in the development of functional materials.

Investigating the superiority of chitosan/D-alpha-tocopheryl polyethylene glycol succinate binary coated bilosomes in promoting the cellular uptake and anti-SARS-CoV-2 activity of polyphenolic herbal drug candidate

The evolution of a safe and effective therapeutic system to conquer SAR-CoV-2 infection deemed to be a crucial worldwide demand. Curcumin (CUR) is a phytomedicinal polyphenolic drug that exhibited a well-reported anti-SAR-CoV-2. However, the therapeutic activity of CUR is hindered by its poor intestinal permeability and diminished aqueous solubility. Therefore, this study strived to develop D-alpha-tocopheryl polyethylene glycol succinate (TPGS) bilosomes (TPGS-Bs) adopting 23 full factorial designs to improve solubility and intestinal permeability of CUR, hence boosting its anti-SARS-CoV-2 activity. Eight experimental runs were attained considering three independent variables: soybean phosphatidylcholine amount (mg) (SPC amount), bile salt amount (mg) (BS amount), and TPGS amount (mg). The optimum formula (F4) exhibited EE % (88.5 ± 2.4 %), PS (181.5 ± 21.6 nm), and ZP (-34.5 ± 3.7 mV) with desirability value = 0.739 was picked as an optimum formula. Furthermore, the optimum formula (F4) was extra coated with chitosan (CS) to improve permeability and anti-SAR-CoV-2 activity. Caco-2 cell uptake after 2 hr revealed the superiority of CS-F4 and F4 by 6 and 5 folds relative to CUR dispersion, respectively. Furthermore, CS-F4 exhibited a significantly higher anti-SARS-CoV-2 activity with IC50 (0.24 µg/ml) by 8.3 times than F4 (1.99 µg/ml). Besides, the mechanistic study demonstrated that the two formulae imparted antiviral activity by inhibiting the spike protein by virucidal potentialities. In addition, the conducted molecular docking and MD simulations towards the SARS-CoV-2 Mpro enzyme confirmed the interaction of CUR with key residues of the virus enzymes. Based on the preceded, CS-F4 could be assumed to be used to effectively eradicate SARS-CoV-2 infection.

Effects of simulated gastrointestinal digestion/epithelial transport on phenolics and bioactivities of particles of brewer's spent yeasts loaded with Brazilian red propolis

Red propolis from northeast Brazil contains mainly isoflavonoids as bioactive compounds, and its consumption may counteract unregulated and exacerbated formation of reactive oxygen species and inflammatory cytokines/chemokines. Moreover, the production of particles using sustainable carriers have been studied to increase the use of propolis as a functional food ingredient. Hence, the objective of this work was to investigate the effects of simulated gastrointestinal digestion followed by a cell-based epithelial transport on phenolic profile, anti-inflammatory and antioxidant activities of particles of brewer's spent yeasts (BSY) loaded with ethanolic extract of Brazilian red propolis (EEP). As a result, the EEP phenolic diversity decreased throughout the simulated gastrointestinal system, and was modulated by the particle production, as detected by high-performance liquid chromatography - electrospray ionization - quadrupole-time-of-flight-mass spectrometry (HPLC-ESI-QTOF-MS). Concomitantly, the antioxidant activity, as assessed by the ability to scavenge peroxyl and superoxide radicals, hydrogen peroxide, and hypochlorous acid, generally decreased at a higher extent for the particles of EEP with BSY (EEP-BSY) throughout the experiments. Nonetheless, after epithelial transport through the Caco-2 cell monolayer, the basolateral fraction of both EEP-BSY and EEP decreased the activation of pro-inflammatory transcription factor NF-κB by 83% and 65%, respectively, as well as the release of TNF-α (up to 51% and 38%, respectively), and CXCL2/MIP-2 (up to 33% and 25%, respectively). Therefore, BSY may be an interesting carrier for EEP bioencapsulation, since it preserves its anti-inflammatory activity. Further studies should be encouraged to investigate the feasibility of adding it in formulations of functional foods, considering its effect on sensory attributes.

Dynamic gastrointestinal digestion/intestinal permeability of encapsulated and nonencapsulated Brazilian red propolis: Active compounds stability and bioactivity

The objectives were to investigate the effect of dynamic gastrointestinal digestion/Caco-2 cell transport on active compounds stability and antioxidant/anti-inflammatory activities of the ethanolic extract of Brazilian red propolis (EEBRP), whether encapsulated or not; and the in vivo acute toxicity of the EEBRP after digestion. Eight isoflavonoids, one flavanone, and one chalcone were identified by HPLC-ESI-QTOF-MS, and quantified by HPLC-PDA. Bioaccessibility was higher for the encapsulated EEBRP (21.4%-57.6%) than for the nonencapsulated (19.3%-30.2%). Conversely, the Caco-2 cell transport was higher for the nonencapsulated EEBRP. Similarly, the nonencapsulated EEBRP showed higher ability to scavenge reactive oxygen species, which was especially attributed to calycosin, and to decrease NF-κB activation, and the levels of TNF-α and CXCL2/MIP-2 after Caco-2 cell transport. Hence, there is an indication that EEBRP is a promising alternative dietary source of bioavailable isoflavonoids. Further studies on encapsulation should be encouraged to improve bioactivity, and expand its food applications.

Lipid Accumulation in Blastocystis Increases Cell Damage in Co-Cultured Cells

Blastocystis hominis is an intestinal protozoan that is often neglected, despite causing abdominal pain and diarrhea. Previous research has demonstrated that lipids can be synthesized by B. hominis or can accumulate in growth medium, but their function and mechanisms in the pathogenesis of Blastocystis remain unclear. Our study found that lipid-rich Blastocystis ST7-B can increase inflammation and disrupt Caco-2 cells more than the same parasite without the lipovenoes supplement. Additionally, the cysteine protease of Blastocystis, a virulence factor, is upregulated and has higher activity in lipid-rich Blastocystis. In order to better understand the effects of lipids on Blastocystis pathogenesis, we treated lipid-lowering pravastatin during Blastocystis ST7-B culturing with a lipovenoes supplement, which decreased the lipid levels of the Blastocystis and reduced the Blastocystis-induced inflammation and cell disruption of Caco-2 cells. We also analyzed the fatty acid composition and possible synthesis pathway in Blastocystis ST7-B, finding significantly higher ratios of arachidonic acid, oleic acid, and palmitic acid than in the other lipid components in lipid-rich Blastocystis ST7-B. These results suggest that lipids play a significant role in the pathogenesis of Blastocystis and provide important information on the molecular mechanisms of and potential treatments for Blastocystis infection.

The Transport and Uptake of Resveratrol Mediated via Glucose Transporter 1 and Its Antioxidant Effect in Caco-2 Cells

Resveratrol has anti-inflammatory, anti-cancer, and anti-aging pharmacological activities. There is currently a gap in academic research regarding the uptake, transport, and reduction of H₂O₂-induced oxidative damage of resveratrol in the Caco-2 cell model. This study investigated the role of resveratrol in the uptake, transport, and alleviation of H₂O₂-induced oxidative damage in Caco-2 cells. In the Caco-2 cell transport model, it was observed that the uptake and transport of resveratrol (10, 20, 40, and 80 μM) were time dependent and concentration dependent. Different temperatures (37 °C vs. 4 °C) could significantly affect the uptake and transportation of resveratrol. The apical to basolateral transport of resveratrol was markedly reduced by STF-31, a GLUT1 inhibitor, and siRNA intervention. Furthermore, resveratrol pretreatment (80 μM) improves the viability of Caco-2 cells induced by H₂O₂. In a cellular metabolite analysis combined with ultra-high performance liquid chromatography-tandem mass spectrometry, 21 metabolites were identified as differentials. These differential metabolites belong to the urea cycle, arginine and proline metabolism, glycine and serine metabolism, ammonia recycling, aspartate metabolism, glutathione metabolism, and other metabolic pathways. The transport, uptake, and metabolism of resveratrol suggest that oral resveratrol could prevent intestinal diseases caused by oxidative stress.

[Effects of Peroxisome Proliferator-Activated Receptor γ on Modulating Angiopoietin-Like Protein 4 Synthesis in Caco-2 Cells Exposed to Clostridium butyricum]

Angiopoietin-like protein 4 (ANGPTL4) is considered to be one of the important circulating mediators linking intestinal microorganisms and host lipid metabolism. The objective of this study was to assess the effects of peroxisome proliferator-activated receptor у (PPARγ) on modulating ANGPTL4 synthesis in Caco-2 cells exposed to Clostridium butyricum. The viability of Caco-2 cells and the expression of PPARγ and ANGPTL4 in Caco-2 cells were detected after the Caco-2 cells were co-cultured with C. butyricum at the concentration of 1 x 10^(6), 1 x 10^(7) and 1 x 10^(8) CFU/mL. The results showed that cell viability was enhanced by C. butyricum. Besides, PPARγ and ANGPTL4 expression and secretion in Caco-2 cells was significantly increased by 1 x 10^(7) and 1 x 10^(8) CFU/mL of C. butyricum. Furthermore, the effects of PPARγ on modulating ANGPTL4 synthesis in Caco-2 cells regulated by 1 x 10^(8) CFU/mL of C. butyricum was also be expounded in PPARγ activation/inhibition model based on Caco-2 cells and via ChIP technique. It was found that C. butyricum promoted the binding of PPARγ to the PPAR binding site (chr19: 8362157-8362357, located upstream of the transcriptional start site of angptl4) of the angptl4 gene in Caco-2 cells. However, the PPARγ was not the only way for C. butyricum to stimulate ANGPTL4 production. Taken together, PPARγ played a role in the regulation of ANGPTL4 synthesis by C. butyricum in Caco-2 cells.

Synergistic Combination of Citrus Flavanones as Strong Antioxidant and COX-Inhibitor Agent

Recently, we demonstrated that a Citrus flavanone mix (FM) shows antioxidant and anti-inflammatory activity, even after gastro-duodenal digestion (DFM). The aim of this study was to investigate the possible involvement of the cyclooxygenases (COXs) in the anti-inflammatory activity previously detected, using a human COX inhibitor screening assay, molecular modeling studies, and PGE2 release by Caco-2 cells stimulated with IL-1β and arachidonic acid. Furthermore, the ability to counteract pro-oxidative processes induced by IL-1β was evaluated by measuring four oxidative stress markers, namely, carbonylated proteins, thiobarbituric acid-reactive substances, reactive oxygen species, and reduced glutathione/oxidized glutathione ratio in Caco-2 cells. All flavonoids showed a strong inhibitory activity on COXs, confirmed by molecular modeling studies, with DFM, which showed the best and most synergistic activity on COX-2 (82.45% vs. 87.93% of nimesulide). These results were also corroborated by the cell-based assays. Indeed, DFM proves to be the most powerful anti-inflammatory and antioxidant agent reducing, synergistically and in a statistically significant manner (p < 0.05), PGE2 release than the oxidative stress markers, also with respect to the nimesulide and trolox used as reference compounds. This leads to the hypothesis that FM could be an excellent antioxidant and COX inhibitor candidate to counteract intestinal inflammation.

Three acidic polysaccharides derived from sour jujube seeds protect intestinal epithelial barrier function in LPS induced Caco-2 cell inflammation model

Normal intestinal epithelial barrier function plays a key role in the prevention of many diseases such as infectious enteritis, inflammatory bowel disease, obesity, etc. In this study, three novel acidic polysaccharides ZY-2, ZY-3 and ZY-4 were isolated from sour jujube (Ziziphus jujuba Mill. var. Spinosa) seeds and purified by DEAE Sephrose Fast Flow gel. The molecular weight of ZY-2, ZY-3 and ZY-4 was 7.76 kDa, 10.71 kDa and 8.31 kDa respectively, mainly composed of different proportions of mannose, rhamnose, glucose, glucuronic acid, galacturonic acid, galactose, xylose and arabinose. ¹H NMR and Congo red experiment results showed that the three polysaccharides mainly contained both α-type and β-type glycosidic bonds with obvious triple helix structural traits. The polysaccharides could up-regulate the expression levels of occludin and ZO-1 in LPS-induced inflammation Caco-2 cells, and reduce IL-6, IL-8, IL-1β and TNF-α significantly. In conclusion, the acidic polysaccharides from sour jujube seeds exhibited great potential in protection intestinal epithelial barrier function through anti-inflammatory effects.

Exosomes derived from EphB2-overexpressing bone marrow mesenchymal stem cells regulate immune balance and repair barrier function

BACKGROUND

Disruption of intestinal barrier function and an imbalance in intestinal immunity are crucial for the occurrence and development of ulcerative colitis. Because of their important roles in regulating inflammation and immunity, exosomes (Exos) released from bone marrow mesenchymal stem cells (BMSCs) may be useful for treating ulcerative colitis. The EphB/EphrinB signaling pathway plays a crucial role in the inflammatory process and the development and function of immune cells, and can mediate long-distance intercellular communication through extracellular vesicles. This study was conducted to explore the effects of pre-modified BMSC-Exos expressing EphB2 (EphB2-Exos) on immunoregulation in vitro.

METHODS

We transfected a lentivirus vector encoding EphB2 into BMSCs and isolated EphB2-Exos from the culture supernatant. Inflammation and oxidative damage in the human colon adenocarcinoma cell line (Caco-2) were induced by dextran sulfate sodium/hydrogen peroxide. In addition, spleen CD4⁺ T lymphocytes of rats were sorted in vitro. We conducted a series of experiments to explore the biological functions of EphB2-Exos.

RESULTS

EphB2-Exos were successfully isolated and were found to significantly protect the activity, proliferation, and migration of Caco-2 cells that were inhibited by dextran sulfate sodium. EphB2-Exos alleviated inflammation and apoptosis and increased the activity of antioxidant enzymes while inhibiting oxidative stress in Caco-2 cells. EphB2-Exos restored intestinal barrier function by inhibiting the RhoA/ROCK pathway and regulated the polarization of CD4⁺T cells.

CONCLUSION

EphB2-Exos enhanced intestinal barrier function and regulated the immune balance by inhibiting the RhoA/ROCK pathway in vitro. These findings suggest that EphB2-Exos can be applied as a cell-free therapy for ulcerative colitis.

Diethylene glycol monoethyl ether-mediated nanostructured lipid carriers enhance trans-ferulic acid delivery by Caco-2 cells superior to solid lipid nanoparticles

This work aimed to compare the performance of trans-ferulic acid-encapsulated nanostructured lipid carriers (NLCs) and solid lipid nanoparticles (SLNs) for transport by Caco-2 cells. The NLC particles (diameter: 102.6 nm) composed of Compritol^® 888 ATO, ethyl oleate, Cremophor^® EL, and Transcutol^® P were larger than the SLNs (diameter: 86.0 nm) formed without liquid lipid (ethyl oleate), and the former had a higher encapsulation efficiency for trans-ferulic acid (p < 0.05). In vitro cultured Caco-2 cell transport was used to simulate intestinal absorption, and the cellular uptake of NLCs was higher than that of SLNs (p < 0.05). Compared to SLNs, NLCs greatly enhanced trans-ferulic acid permeation through the Millicell^TM membrane (p < 0.05). This work confirms that NLCs have better properties than SLNs in terms of increasing drug transport by Caco-2 cells. This helps to comprehend the approach by which NLC-mediated oral bioavailability of trans-ferulic acid is better than that mediated by SLNs, as shown in our previous report.

Bridging biotechnology and nanomedicine to produce biogreen whey-nanovesicles for intestinal health promotion

New intestinal health-promoting biotechnological nanovesicles were manufactured by combining the main environmental pollutant generated from the cheese-making process, whey, with phospholipid, sodium hyaluronate and dextrin, thus overcoming environmental and medical challenges. An efficient, consolidated and eco-friendly preparation method was employed to manufacture the vesicles and the bioactive whey was obtained by mesophilic dark fermentation without external inoculum through a homolactic pathway, which was operated in such a way as to maximize the production of lactic acid. The biotechnological nutriosomes and hyalonutriosomes were relatively small (∼100 nm) and characterized by the net negative surface charge (>-30 mV). The addition of maltodextrin to the liposomes and especially to the hyalurosomes significantly stabilized the vesicles under acidic conditions, simulating the gastric environment, as their size and polydispersity index were significantly lower (p < 0.05) than those of the other formulations. The vesicles were effectively internalized by Caco-2 cells and protected them against oxidative stress. Nutriosomes promoted the proliferation of Streptococcus salivarius, a human commensal bacterium, to a better extent (p < 0.05) than liposomes and hyalurosomes, as a function of the concentration tested. These findings could open a new horizon in intestinal protection and health promotion by integrating biotechnology, nanomedicine, sustainability principles and bio-circular economy.

Enhancing Oral Bioavailability of Domperidone Maleate: Formulation, In-Vitro Permeability Evaluation, In-Caco-2 cell Monolayers and In-Situ Rat Intestinal Permeability Studies

BACKGROUND

The domperidone maleate, a lipophilic agent classified as a Biopharmaceutical Classification System Class II substance with weak water solubility. Self- Emulsifying Drug Delivery System is a novel approach to improve water solubility and, ultimately bioavailability of drugs.

OBJECTIVE

This study aimed to develop and characterize new domperidone-loaded self-emulsifying drug delivery systems as an alternative formulation and to evaluate the permeability of domperidone-loaded self-emulsifying drug delivery systems by using Caco-2 cells and via single-pass intestinal perfusion method.

METHOD

Three self-emulsifying drug delivery systems were prepared and characterized in terms of pH, viscosity, droplet size, zeta potential, polydispersity index, conductivity, etc. Each formulation underwent 10, 100, 200, and 500 times dilution in intestinal buffer pH 6.8 and stomach buffer pH 1.2, respectively. Female Sprague Dawley rats were employed for in situ single-pass intestinal perfusion investigations.

RESULTS

Results of the study revealed that the ideal self-emulsifying drug delivery systems formulation showed narrow droplet size, ideal zeta potential, and no conductivity. Additionally, as compared to the control groups, the optimum formulation had better apparent permeability (12.74 ± 0.02×10-4) from Caco-2 cell monolayer permeability experiments. The study also revealed greater Peff values (2.122 ± 0.892×10-4 cm/s) for the optimal formulation from in situ intestinal perfusion analyses in comparison to control groups (Domperidone; 0.802±0.418×10-4 cm/s).

CONCLUSION

To conclude, prepared formulations can be a promising way of oral administration of Biopharmaceutical Classification System Class II drugs.

Cytotoxicity and intestinal permeability of phycotoxins assessed by the human Caco-2 cell model

Phycotoxins are a class of multiple natural metabolites produced by microalgae in marine and freshwater ecosystems that bioaccumulate in food webs, particularly in shellfish, having a great impact on human health. Phycotoxins are mainly leached and absorbed in the small intestine when human consumers accidentally ingest toxic aquatic products contaminated by them. To assess the intestinal uptake and damage of phycotoxins, a typical in vitro model was developed and widely applied using the human colorectal adenocarcinoma Caco-2 cell line. In this review, the application cases were summarized for multiple phycotoxins, including microcystins (MCs), cylindrospermopsins (CYNs), domoic acids (DAs), saxitoxins (STXs), palytoxins (PLTXs), okadaic acids (OAs), pectenotoxins (PTXs) and azaspiracids (AZAs). The results of the previous studies showed that each group of phycotoxins presented different cytotoxicity and mechanisms to Caco-2 cells, and significant discrepancies in the transport of phycotoxin across the Caco-2 cell monolayers. Therefore, this review describes the evaluation assays of the Caco-2 cell monolayer model, illustrates the principles of several primary cytotoxicity evaluation assays, and summarizes the cytotoxicity of each group of phycotoxins to Caco-2 cells line and their cellular transport, and finally proposes the development of multicellular intestinal models for future comprehensive studies on the toxicity and absorption of phycotoxins in the intestine. It will improve the understanding of Caco-2 cell monolayer models in the toxicology studies on phycotoxins and the potentially detrimental effects of microalgal toxins on the human intestine.

Chestnuts in Fermented Rice Beverages Increase Metabolite Diversity and Antioxidant Activity While Reducing Cellular Oxidative Damage

Foods containing chestnuts (Castanea mollissima Blume) are relatively uncommon, despite the high nutrient and starch contents and purported health benefits. In this study, we examine the flavor-related metabolites, volatile compounds, and amino acids in a traditional glutinous rice fermented beverage supplemented with chestnuts as a fermentation substrate for lactic acid bacteria (LAB). Changes in antioxidant activity towards free radicals and effects on cellular oxidative stress are compared between beverages with or without chestnuts. The fermented chestnut-rice beverage (FCRB) has higher sensory scores and a wider range of volatiles and flavor-related compounds (74 vs. 38 species compounds), but lower amino acid contents, than the traditional fermented glutinous rice beverage (TFRB). In free radical scavenging assays, the FCRB exhibits higher activity than the TFRB in vitro. Furthermore, while neither beverage induces cytotoxity in Caco-2 cells at concentrations up to 2 mg/mL, pretreatment with the FCRB results in lower rates of apoptosis and necrosis and higher overall viability in cells with H₂O₂-induced oxidative stress compared to pretreatment with the TFRB. The enhanced reactive oxygen species neutralization in vitro and protection against oxidative damage in cells, coupled with increased diversity of volatiles and flavor-related metabolites of LAB, support the addition of chestnuts to enhance flavor profile and antioxidant properties of fermented functional foods.

Probiotic Properties of Chicken-Derived Highly Adherent Lactic Acid Bacteria and Inhibition of Enteropathogenic Bacteria in Caco-2 Cells

Lactic acid bacteria (LAB) as probiotic candidates have various beneficial functions, such as regulating gut microbiota, inhibiting intestinal pathogens, and improving gut immunity. The colonization of the intestine is a prerequisite for probiotic function. Therefore, it is necessary to screen the highly adherent LAB. In this study, the cell surface properties, such as hydrophobicity, auto-aggregation, co-aggregation, and adhesion abilities of the six chicken-derived LAB to Caco-2 cells were investigated. All six strains showed different hydrophobicity (21.18-95.27%), auto-aggregation (13.61-30.17%), co-aggregation with Escherichia coli ATCC 25922 (10.23-36.23%), and Salmonella enterica subsp. enterica serovar Typhimurium ATCC 13311 (11.71-39.35%), and adhesion to Caco-2 cells (8.57-26.37%). Pediococcus pentosaceus 2-5 and Lactobacillus reuteri L-3 were identified as the strains with strong adhesion abilities (26.37% and 21.57%, respectively). Moreover, these strains could survive in a gastric acid environment at pH 2, 3, and 4 for 3 h and in a bile salt environment at 0.1%, 0.2%, and 0.3% (w/v) concentration for 6 h. Furthermore, the cell-free supernatant of P. pentosaceus 2-5 and L. reuteri L-3 inhibited the growth of enteropathogenic bacteria and the strains inhibited the adhesion of these pathogens to Caco-2 cells. In this study, these results suggested that P. pentosaceus 2-5 and L. reuteri L-3, isolated from chicken intestines might be good probiotic candidates to be used as feed additives or delivery vehicles of biologically active substances.

Increasing Cellular Uptake and Permeation of Curcumin Using a Novel Polymer-Surfactant Formulation

Several therapeutically active molecules are poorly water-soluble, thereby creating a challenge for pharmaceutical scientists to develop an active solution for their oral drug delivery. This study aimed to investigate the potential for novel polymer-surfactant-based formulations (designated A and B) to improve the solubility and permeability of curcumin. A solubility study and characterization studies (FTIR, DSC and XRD) were conducted for the various formulations. The cytotoxicity of formulations and commercial comparators was tested via MTT and LDH assays, and their permeability by in vitro drug transport and cellular drug uptake was established using the Caco-2 cell model. The apparent permeability coefficients (Papp) are considered a good indicator of drug permeation. However, it can be argued that the magnitude of Papp, when used to reflect the permeability of the cells to the drug, can be influenced by the initial drug concentration (C₀) in the donor chamber. Therefore, Papp (suspension) and Papp (solution) were calculated based on the different values of C₀. It was clear that Papp (solution) can more accurately reflect drug permeation than Papp (suspension). Formulation A, containing Soluplus^® and vitamin E TPGs, significantly increased the permeation and cellular uptake of curcumin compared to other samples, which is believed to be related to the increased aqueous solubility of the drug in this formulation.

Medium Chain Triglycerides Promote the Uptake of β-Carotene in O/W Emulsions via Intestinal Transporter SR-B1 in Caco-2 Cells

This study aimed to elucidate the impacts of carrier oil types (long chain triglycerides (LCT), medium chain triglycerides (MCT), and orange oil (indigestible oil)) on the micellization and cellular uptake of β-carotene (BC) formulated in O/W emulsions, with an emphasis on the role of intestinal transporters. The micellization and cellular uptake of BC in the gastrointestinal tract were evaluated via an in vitro digestion model and a Caco-2 cell monolayer. And the interactions between lipids and intestinal transporters were monitored by nontargeted lipidomics, RT-PCR, and Western blot. The BC micellization rates followed a decreasing trend in emulsions: corn oil (69.47 ± 4.19%) > MCT (22.22 ± 0.89%) > orange oil (11.01 ± 2.86%), whereas the cellular uptake rate of BC was significantly higher in MCT emulsion (56.30 ± 20.13%) than in corn oil emulsion (14.01 ± 1.04%, p < 0.05). The knockdown of SR-B1 led to a 31.63% loss of BC cellular uptake from MCT micelles but had no effect on corn oil micelles. Lipidomics and transporter analysis revealed that TG (10:0/10:0/12:0) and TG (10:0/12:0/12:0) might be the fingerprint lipids that promoted the cellular absorption of BC-MCT micelles via stimulating the mRNA expression of SR-B1.

Bioavailability of Peptides Derived from the In Vitro Digestion of Human Milk Assessed by Caco-2 Cell Monolayers

Human milk-protein-derived peptides exhibit an array of bioactivities. Certain bioactivities cannot be exerted unless the peptides are absorbed across the gastrointestinal lumen into the bloodstream. The purpose of study was to determine which peptides derived from in vitro digestion of human milk could cross human intestinal Caco-2 cell monolayers. Our results showed that the numbers of peptides absorbed by the Caco-2 cell monolayer were different at different concentrations (44 peptides out of 169 peptides detected at 10 μg/mL, 124 peptides out of 204 peptides detected at 100 μg/mL, and 175 peptides out of 236 peptides detected at 1000 μg/mL). Four peptides (NLHLPLP (β-casein [138-144]), PLAPVHNPI (β-casein [216-224]), PLMQQVPQPIPQ (β-casein [148-159]), and FDPQIPK (β-casein [126-132])) crossed to the basolateral chamber of the Caco-2 monolayer incubated with peptides at all three concentrations. Among the peptides identified in the basolateral chambers, three peptides (NLHLPLP (β-casein [138-144]), LENLHLPLP (β-casein [136-144]), and QVVPYPQ (β-casein [182-188])) are known ACE-inhibitors; one peptide (LLNQELLLNPTHQIYPV (β-casein [197-213])) is antimicrobial, and another peptide (QVVPYPQ (β-casein [182-188])) has antioxidant activity. These findings indicate that specific milk peptides may be able to reach the bloodstream and exert bioactivity.

Genotyping Based on CRISPR Loci Diversity and Pathogenic Potential of Diarrheagenic Escherichia coli

Diarrheagenic Escherichia coli (DEC) can cause epidemic diarrhea worldwide. The pathogenic potential of different strains is diverse and the continuous emergence of pathogenic strains has brought serious harm to public health. Accurately distinguishing and identifying DEC with different virulence is necessary for epidemiological surveillance and investigation. Clustered regularly interspaced short palindromic repeats (CRISPR) typing is a new molecular method that can distinguish pathogenic bacteria excellently and has shown great promise in DEC typing. The purpose of this study was to investigate the discrimination of CRISPR typing method for DEC and explore the pathogenicity potential of DEC based on CRISPR types (CT). The whole genome sequences of 789 DEC strains downloaded from the database were applied CRISPR typing and serotyping. The D value (Simpson’s index) with 0.9709 determined that CRISPR typing had a higher discrimination. Moreover, the same H antigen strains with different O seemed to share more identical spacers. Further analyzing the strains CRISPR types and the number of virulence genes, it was found that there was a significant correlation between the CRISPR types and the number of virulence genes (p < 0.01). The strains with the largest number of virulence genes concentrated in CT25 and CT56 and the number of virulence genes in CT264 was the least, indicating that the pathway potential of different CRISPR types was variable. Combined with the Caco-2 cell assay of the laboratory strains, the invasion capacity of STEC strains of different CRISPR types was different and there was no significant difference in the invasion rate between different CRISPR type strains (p > 0.05). In the future, with the increase of the number of strains that can be studied experimentally, the relationship between CRISPR types and adhesion and invasion capacities will be further clarified.

SEDDS facilitate cinnamaldehyde crossing the mucus barrier: The perspective of mucus and Caco-2/HT29 co-culture models

Self-emulsifying drug delivery systems (SEDDS) have potential applications in the delivery of hydrophobic components. Oral drugs are readily captured and cleared by intestinal mucus, a natural barrier that covers the mucosal epithelium and prevents the entry of foreign substances. In this study, we investigated for the first time the ability of SEDDS to deliver the lipophilic aldehyde cinnamaldehyde (CA-SEDDS) in rat mucus, mucin solution, Caco-2 and Caco-2/HT29 co-culture monolayer systems. CA-SEDDS was characterized by particle size, Zeta potential and the logD_{SEDDS/release medium}. The capacity of CA-SEDDS to enhance mucus permeability was investigated in rat intestinal mucus gel and mucin solution with the period of in 12 h by Transwell® diffusion. We evaluated the potential of CA-SEDDS delivery of CA in a co-culture system of absorptive Caco-2 and mucus-secreting HT29 cells. CA-SEDDS exhibited excellent mucus permeability in mucus and mucin solutions, 5.1- and 2.8-fold higher than the free CA group, respectively. CA-SEDDS penetration increased by 2.5-fold compared with free CA when using the mucus-secreting co-culture cell model as a barrier. The relative oral bioavailability of CA-SEDDS was 242% compared to CA without formulation. These findings suggest that SEDDS exhibited good release and superior mucus permeability, displaying great potential for the future of hydrophobic oral applications.

The pharmaceutical excipient PEG400 affect the absorption of baicalein in Caco-2 monolayer model by interacting with UDP-glucuronosyltransferases and efflux transport proteins

The bioavailability of drugs is often related to intestinal metabolism and transport mechanisms. In previous studies, pharmaceutical excipients were recognized as inert substances in clinical safety evaluations. However, a large number of studies have shown that pharmaceutical excipients regulate the metabolism and transport of drugs in the body and improve the bioavailability. The pharmaceutical excipient polyethylene glycol 400 (PEG400) as a good solubilizer and surfactant has the potential to improve the bioavailability of drugs. The combined action of UDP-glucuronosyltransferases (UGTs) and efflux transport proteins is responsible for the intestinal disposition and poor bioavailability of baicalein. Our aim is to study the effect of PEG400 on the absorption of baicalein on the Caco-2 monolayer, and confirm the interaction of PEG400 with UGTs (UGT1A8 and UGT1A9) and efflux transports. We initially found that baicalein in the Caco-2 monolayer would be metabolized into glucuronide conjugates BG and B6G under the action of UGT1A8 and UGT1A9 on the endoplasmic reticulum membrane, and then mainly excreted to different sides by acting of MRP and BCRP. The addition of PEG400 significantly accelerated the metabolism of B in Caco-2 cells and increased the penetration of BG and B6G. Furthermore, PEG400 also significantly decreased the efflux ratio of BG and B6G, which was the evidence of the interaction with the efflux transporters. In the in vitro intestinal microsome regeneration system, low concentration PEG400 decreased the K_m value of UGT1A8 and UGT1A9 (key enzymes that mediate the production of BG and B6G); high concentration PEG400 enhanced the V_max value of UGT1A8 and UGT1A9. In conclusion, our results determined that PEG400 interacted with some UGTs and efflux transporters, which were the main factors affecting the absorption of baicalein.

Generation of Caco-2 cells stably expressing CYP3A4·POR·UGT1A1 and CYP3A4·POR·UGT1A1*6 using a PITCh system

The small intestine plays a critical role in the absorption and metabolism of orally administered drugs. Therefore, a model capable of evaluating drug absorption and metabolism in the small intestine would be useful for drug discovery. Patients with genotype UGT1A1*6 (exon 1, 211G > A) treated with the antineoplastic drug SN-38 have been reported to exhibit decreased glucuronide conjugation and increased incidence of intestinal toxicity and its severe side effects, including severe diarrhea. To ensure the safety of drugs, we must develop a drug metabolism and toxicity evaluation model which considers UGT1A1*6. In this study, we generated CYP3A4·POR·UGT1A1 KI- and CYP3A4·POR·UGT1A1*6 KI-Caco-2 cells for pharmaceutical research using a PITCh system. The CYP3A4·POR·UGT1A1 KI-Caco-2 cells were shown to express functional CYP3A4 and UGT1A1. The CYP3A4·POR·UGT1A1*6 KI-Caco-2 cells were sensitive to SN-38-induced intestinal toxicity. We thus succeeded in generating CYP3A4·POR·UGT1A1 KI- and CYP3A4·POR·UGT1A1*6 KI-Caco-2 cells, which can be used in pharmaceutical research. We also developed an intestinal epithelial cell model of patients with UGT1A1*6 and showed that it was useful as a tool for drug discovery.

3,5,7,3',4'-Pentamethoxyflavone Enhances the Barrier Function through Transcriptional Regulation of the Tight Junction in Human Intestinal Caco-2 Cells

The intestinal tight junction (TJ) barrier plays a pivotal role in the regulation of intestinal homeostasis. This study investigated the effects of 3,5,7,3',4'-pentamethoxyflavone (PMF), a major polymethoxyflavone found in black ginger, on TJ barrier regulation using intestinal Caco-2 cells. PMF treatment enhanced the TJ barrier integrity in Caco-2 cells, indicated by increased transepithelial electrical resistance (control, 1261 ± 36 Ω·cm²; 100 μM PMF, 1383 ± 55 Ω·cm² at 48 h, p < 0.05) and decreased permeability to fluorescein-conjugated dextran (control, 24.2 ± 1.8 pmol/(cm² × h); 100 μM PMF, 18.6 ± 1.0 pmol/(cm² × h), p < 0.05). Immunoblot analysis revealed that PMF increased the cytoskeletal association and cellular expression of the TJ proteins, zonula occludens-1, claudin-3, and claudin-4 (e.g., occludin; control, 1.00 ± 0.2; 100 μM PMF, 3.69 ± 0.86 at 48 h, p < 0.05). Quantitative reverse transcriptase-polymerase chain reaction analysis and a luciferase promoter assay showed that PMF enhanced the transcription of occludin, claudin-3, and claudin-4. The promoter assay with site-directed mutagenesis indicated that PMF-induced occludin and claudin-3 transcription was mediated by transcription factors, KLF5 and EGR1, respectively, while PMF activated claudin-4 transcription through GATA1 and AP1. Taken together, the transcriptional regulation of TJ proteins is involved in PMF-mediated promotion of the intestinal barrier in vitro.

Low-Molecular-Weight Fucoidan as Complementary Therapy of Fluoropyrimidine-Based Chemotherapy in Colorectal Cancer

This study investigated the roles of low-molecular-weight fucoidan (LMWF) in enhancing the anti-cancer effects of fluoropyrimidine-based chemotherapy. HCT116 and Caco-2 cells were treated with LMWF and 5-FU. Cell viability, cell cycle, apoptosis, and migration were analyzed in both cell types. Potential mechanisms underlying how LMWF enhances the anti-cancer effects of fluoropyrimidine-based chemotherapy were also explored. The cell viability of HCT116 and Caco-2 cells was significantly reduced after treatment with a LMWF-–5FU combination. In HCT116 cells, LMWF enhanced the suppressive effects of 5-FU on cell viability through the (1) induction of cell cycle arrest in the S phase and (2) late apoptosis mediated by the Jun-N-terminal kinase (JNK) signaling pathway. In Caco-2 cells, LMWF enhanced the suppressive effects of 5-FU on cell viability through both the c-mesenchymal–epithelial transition (MET)/Kirsten rat sarcoma virus (KRAS)/extracellular signal-regulated kinase (ERK) and the c-MET/phosphatidyl-inositol 3-kinases (PI3K)/protein kinase B (AKT) signaling pathways. Moreover, LMWF enhanced the suppressive effects of 5-FU on tumor cell migration through the c-MET/matrix metalloproteinase (MMP)-2 signaling pathway in both HCT116 and Caco-2 cells. Our results demonstrated that LMWF is a potential complementary therapy for enhancing the efficacies of fluoropyrimidine-based chemotherapy in colorectal cancers (CRCs) with the wild-type or mutated KRAS gene through different mechanisms. However, in vivo studies and in clinical trials are required in order to validate the results of the present study.

PCSK9 is not secreted from mature differentiated intestinal cells

Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes lysosomal degradation of the LDL receptor and is a key regulator of cholesterol metabolism. After the liver, the small intestine is the second organ that highly expresses PCSK9. However, the small intestine's ability to secrete PCSK9 remains a matter of debate. While liver-specific PCSK9-deficient mice present no PCSK9 in systemic blood, human intestinal Caco-2 cells can actively secrete PCSK9. This raises the possibility for active intestinal secretion via the portal blood. Here, we aimed to determine whether enterocytes can secrete PCSK9 using in vitro, ex vivo, and in vivo approaches. We first observed that PCSK9 secretion from Caco-2 cells was biphasic and dependent on Caco-2 maturation status. Transcriptional analysis suggested that this transient reduction in PCSK9 secretion might be due to loss of SREBP2-mediated transcription of PCSK9. Consistently, PCSK9 secretion was not detected ex vivo in human or mouse intestinal biopsies mounted in Ussing chambers. Finally, direct comparison of systemic versus portal blood PCSK9 concentrations in WT or liver-specific PCSK9-deficient mice confirmed the inability of the small intestine to secrete PCSK9 into the portal compartment. Altogether, our data demonstrate that mature enterocytes do not secrete PCSK9 and reinforce the central role of the liver in the regulation of the concentration of circulating PCSK9 and consequently of cellular LDL receptors.

Influence of the co-exposure of microplastics and tetrabromobisphenol A on human gut: Simulation in vitro with human cell Caco-2 and gut microbiota

Microplastics (MPs) pollution becomes an emergent threat to the ecosystem, and its joint effect with organic contaminants will cause more severe consequences. Recently, MPs has been observed in human feces, suggesting that we are exposed to an uncertain danger. In this study, the joint effect of polyethylene microplastics particles (PEMPs) and Tetrabromobisphenol A (TBBPA) on human gut was explored through the simulation experiment in vitro with human cell Caco-2 and gut microbiota. The toxicity of TBBPA and PEMPs on Caco-2 human cells was considered by physiological and biochemical indexes such as cell proliferation, cell cycle, reactive oxygen species, lactate dehydrogenase release, and mitochondrial membrane potential. Besides, microbial community diversity, community structure, and function changes of gut microbiota were investigated using Illumina 16S rRNA gene MiSeq sequencing to reveal the influence of TBBPA and PEMPs on human gut microbiota. The results indicated that both PEMPs and TBBPA would deteriorate the status of Caco-2 cells, and TBBPA played a major role in it; meanwhile, PEMPs affected Caco-2 cells at high concentrations. Particularly, TBBPA and PEMPs exhibited a joint effect on Caco-2 cells to a certain degree. TBBPA selectivity inhibited the growth of gram-positive bacteria such as Enterococcus and Lactobacillus, contributing to the thriving of gram-negative bacteria such as Escherichia and Bacteroides. The existence of PEMPs would enhance the proportion of Clostridium, Bacteroides, and Escherichia. Community composition changed dramatically with the interference of PEMPs and TBBPA; this was undesirable to the healthy homeostasis of the human gut. PICRUSt analysis determined both PEMPs and TBBPA interfered with the metabolism pathways of gut microbiota. Hence, the threat of MPs and TBBPA to humans should arouse vigilance.

[Study on oral absorption mechanisms of puerarin in nanocrystals self-stabilized pickering emulsion]

Nanocrystals self-stabilized Pickering emulsion(NSSPE) is a new kind of emulsion where only nanocrystals of poorly soluble drugs are used as stabilizers. Our previous study showed that NSSPE with Ligusticum chuanxiong oil as the main oil phase can significantly promote oral absorption of puerarin. The present study aimed to explore its absorption mechanism in oral administration. The in vitro dissolution test was carried out to study the effect of NSSPE on release of puerarin. The effects and mechanism of NSSPE on uptake and transport of puerarin across Caco-2 cell were investigated. The results showed that the drug release rate of NSSPE was similar to that of nanocrystals, with their cumulative dissolution of puerarin not affected by pH of releasing mediums, both significantly higher than that of crude material. The uptake of puerarin in NSSPE was concentration-dependent and significantly higher than that of solution or surfactant stabilized emulsion. Genistein and indomethacin, inhibitors of lipid rafts/caveolin, could significantly reduce the uptake of puerarin in NSSPE. Compared with solution, NSSPE and surfactants stabilized emulsion obviously increased transport rate K_a and apparent permeability coefficient P_(app) of puerarin in AP → BL direction, but there was no significant difference in BL → AP direction. It could be inferred that there were both passive and active transport mechanisms, as well as lipid raft/caveolin mediated endocytosis for absorption of NSSPE. The promoted oral absorption of puerarin in NSSPE was mainly related to the existing nanocrystal form which could promote dissolution, puerarin as well as Ligusticum chuanxiong oil which could promote drug transmembrane transport and inhibit drug efflux. It is the unique structure and composition of the compound NSSPE that promoted the oral absorption of puerarin.

Enhanced water dispersibility and permeability through a Caco-2 cell monolayer of β-cryptoxanthin extracted from kumquats by complexation with casein

β-Cryptoxanthin (BCX) possesses potential therapeutic and health benefits. However, BCX absorption is low because of its poor aqueous solubility. In this study, a complex between BCX and casein (Cas) was prepared to improve the water dispersibility and bioavailability of BCX. BCX was recovered quantitatively from freeze-dried kumquat powder through solid-liquid extraction and saponification. The complexation significantly improved the apparent solubility of BCX under acidic and neutral conditions. A cell membrane permeation test using a Caco-2 cell monolayer was performed to evaluate the bioavailability of the BCX-Cas complex. This complex and a blank sample were digested in vitro and added to the apical side of the Caco-2 cell membrane. The quantity of BCX that permeated using the BCX-Cas complex after 24 h was 22.7 times greater than that of the blank. Thus, complexation of BCX with Cas improved dramatically the bioavailability of BCX from a kumquat extract.

Arabinogalactan in the side chain of pectin from persimmon is involved in the interaction with small intestinal epithelial cells

Pectin in Diospyros kaki (persimmon) is a complex polysaccharide and is classified as a dietary fiber. Pectin is characterized by the presence of side chains of neutral sugars, such as galactose residues; however, the structure and properties of these sugars vary greatly depending on the plant species from which it is derived. Here, we report the structural features of pectin extracted from persimmon. The polysaccharide was low-methoxy pectin with a degree of methyl esterification <50% and ratio of side chain galactan to arabinan in the rhamnogalacturonan-I region of pectin of 3-20. To investigate the physiological function of pectin from persimmon, we performed a coculture assay using Caco-2 cells. As a result, it was shown that the proliferation of undifferentiated Caco-2 cells was promoted, and further, the importance of arabinogalactan among the pectin structures was shown.

Inhibitory effect of different chicken-derived lactic acid bacteria isolates on drug resistant Salmonella SE47 isolated from eggs

Lactic Acid Bacteria (LAB) regulate and maintain the stability of healthy microbial flora, inhibit the adhesion of pathogenic bacteria and promote the colonization of beneficial micro-organisms. The drug resistance and pathogenicity of Salmonella enteritis SE47 isolated from retail eggs were investigated. Meanwhile, Enterococcus faecalis L76 and Lactobacillus salivarius LAB35 were isolated from intestine of chicken. With SE47 as indicator bacteria, the diameters of L76 and LAB35 inhibition zones were 12 mm and 8·5 mm, respectively, by agar inhibition circle method, which indicated that both of them had inhibitory effect on Salmonella, and L76 had better antibacterial effect; two chicken-derived lactic acid bacteria isolates and Salmonella SE47 were incubated with Caco-2. The adhesion index of L76 was 17·5%, which was much higher than that of LAB35 (10·21%) and SE47 (4·89%), this experiment shows that the higher the bacteriostatic effect of potential probiotics, the stronger the adhesion ability; then Caco-2 cells were incubated with different bacteria, and the survival of Caco-2 cells was observed by flow cytometry. Compared with Salmonella SE47, the results showed that lactic acid bacteria isolates could effectively protect Caco-2 cells; finally, after different bacteria incubated Caco-2 cells, according to the cytokine detection kit, the RNA of Caco-2 cells was extracted and transcribed into cDNA, then detected by fluorescence quantitative PCR, the results showed that L76 could protect Caco-2 cells from the invasion of Salmonella SE47, with less cell membrane rupture and lower expression of MIF and TNF genes. Therefore, the lactic acid bacteria isolates can effectively inhibit the adhesion of Salmonella and protect the integrity of intestinal barrier.

Electrospun Scaffold for Biomimic Culture of Caco-2 Cell Monolayer as an In Vitro Intestinal Model

The Caco-2 cell monolayer has been extensively used for the high-throughput assessing of nutrient absorption, screening of drug permeability, and studying the intestinal physiological process in vitro. The most used Caco-2 cell model is the Transwell model with polycarbonate microporous membranes. However, Caco-2 cells in the classical Transwell model need 21 days to gain an intact and mature monolayer. Electrospun nanofiber scaffolds mimicking the natural extracellular matrix could improve cell adhesion, proliferation, and expression, whereas there are no reports that intestinal cells were cultured on the electrospun nanofiber scaffolds. Here, electrospun polylactic acid (PLA) nanofiber scaffolds were chosen as the ideal scaffolds for Caco-2 cell monolayers to construct a modified Transwell. Cell morphology and polarity were studied. Monolayer barrier properties were assessed by measuring transepithelial electrical resistance (TEER) and the leakage of phenol red. As found, intact Caco-2 cell monolayers were formed on the PLA nanofiber scaffolds after 4 days of culture. After 4 days, the TEER increased to 422 Ω·cm² and the apparent permeability coefficients of phenol red decreased to 1.0 ± 0.1 × 10^-6 cm/s, suggesting that Caco-2 cell monolayers developed a formidable barrier to small molecules on the surface of PLA nanofiber scaffolds. Microvilli and tight junctions were clearly visible after day 3. Besides, Caco-2 cell monolayers on the surface of PLA nanofiber scaffolds presented higher differentiation properties than on the surface of the polycarbonate microporous membrane in traditional Transwell including higher alkaline phosphatase activity and higher P-gp activity. Results of quercetin absorption and probiotics adhesion demonstrated that Caco-2 cell monolayers formed on the surface of PLA nanofiber scaffolds also had better physiological function and prediction function in vitro. Overall, the present study indicated that the Transwell with the structurally and functionally biomimetic electrospun PLA nanofiber scaffold could be potentially developed as a promising in vitro intestinal model.

Analysis of α-Defensin 5 Secretion in Differentiated Caco-2 Cells: Comparison of Cell Bank Origin

α-Defensin 5 has a particularly broad antibacterial spectrum; it eliminates pathogenic microorganisms and regulates intestinal flora. Although Caco-2 cells are similar to small intestinal cells, it is unclear whether they secrete α-defensin 5. Therefore, we investigated whether Caco-2 cells secrete α-defensin 5 and determined the secretion mechanism using cells from three cell banks (ATCC, DSMZ, and RIKEN). The Caco-2 cell proliferation rate increased with the number of culture days, irrespective of cell bank origin. On the other hand, the alkaline phosphatase activity, which affects cell differentiation and the mRNA levels of several cytokines, such as interleukin 8 (IL-8), IL-6, IL-1β, tumor necrosis factor-α (TNF-α), and IL-2, in the Caco-2 cells fluctuated with the number of culture days, and differed for each cell bank. α-Defensin 5 secretion was detected in all three cell bank Caco-2 cells; particularly, the ATCC Caco-2 cells grew linearly depending on the cell culture day as well as the levels of IL-8 and TNF-α mRNA. This suggested that α-defensin 5 secretion in the ATCC Caco-2 cells was associated with fluctuations in the mRNA levels of various cytokines, such as IL-8 and TNF-α. In conclusion, Caco-2 cells may be a simple model for screening health food components and drugs that affect α-defensin 5 secretion.

The bioactivity of colostrum and milk exosomes of high, average, and low immune responder cows on human intestinal epithelial cells

Bovine milk contains bioactive components that are nutritionally and immunologically important to calves and humans. Dairy cows classified as high (H) immune responders using the patented high immune response technology have higher concentrations of immunoglobulin and specific antibodies in sera and milk compared with average (A) and low (L) responders. MicroRNA post-transcriptionally regulate expression of milk bioactive components and are enriched in extracellular vesicles known as exosomes, which protect them from degradation. The bioactivity of colostrum and milk exosomes at the human intestinal epithelial barrier remains to be explored, particularly in the context of the high immune response technology. Therefore, the purpose of this study was to evaluate the functional role of bovine milk exosomes compared with colostrum exosomes from H, A, and L responders at the intestinal interface using human colorectal adenocarcinoma epithelial (Caco-2) cells. Exosomes were isolated by successive ultracentrifugation and confirmed by western blot analysis for the presence of common exosomal proteins (CD9, CD63, and heat shock protein 70). Fluorescent labeling of exosomes using PKH67 dye confirmed their uptake by Caco-2 cells, demonstrating their potential bioavailability. The MTT assays showed that colostrum and milk exosomes maintain Caco-2 metabolic activity and are not cytotoxic to these cells. Specifically, metabolic activity after co-incubation with colostrum and milk exosomes from H responder cows was significantly greater than after co-incubation with exosomes from L responders. Caspase 3 activity, an indicator of apoptosis, was significantly lower after co-incubation of Caco-2 cells with milk exosomes compared with colostrum exosomes, suggesting that unlike colostrum exosomes, particularly those from L responders, milk exosomes do not activate the caspase 3 pathway in Caco-2 cells. This study helps us better understand the functional importance of colostrum and milk exosomes from dairy cows and emphasizes differences in functionality among exosomes from H, A, and L immune responders.

pH-dependent pyridoxine transport by SLC19A2 and SLC19A3: Implications for absorption in acidic microclimates

SLC19A2 and SLC19A3, also known as thiamine transporters (THTR) 1 and 2, respectively, transport the positively charged thiamine (vitamin B1) into cells to enable its efficient utilization. SLC19A2 and SLC19A3 are also known to transport structurally unrelated cationic drugs, such as metformin, but whether this charge selectivity extends to other molecules, such as pyridoxine (vitamin B6), is unknown. We tested this possibility using Madin-Darby canine kidney II (MDCKII) cells and human embryonic kidney 293 (HEK293) cells for transfection experiments, and also using Caco-2 cells as human intestinal epithelial model cells. The stable expression of SLC19A2 and SLC19A3 in MDCKII cells (as well as their transient expression in HEK293 cells) led to a significant induction in pyridoxine uptake at pH 5.5 compared with control cells. The induced uptake was pH-dependent, favoring acidic conditions over neutral to basic conditions, and protonophore-sensitive. It was saturable as a function of pyridoxine concentration, with an apparent Km of 37.8 and 18.5 μm, for SLC19A2 and SLC19A3, respectively, and inhibited by the pyridoxine analogs pyridoxal and pyridoxamine as well as thiamine. We also found that silencing the endogenous SLC19A3, but not SLC19A2, of Caco-2 cells with gene-specific siRNAs lead to a significant reduction in carrier-mediated pyridoxine uptake. These results show that SLC19A2 and SLC19A3 are capable of recognizing/transporting pyridoxine, favoring acidic conditions for operation, and suggest a possible role for these transporters in pyridoxine transport mainly in tissues with an acidic environment like the small intestine, which has an acidic surface microclimate.

Transport Characteristics of 5-Aminosalicylic Acid Derivatives Conjugated with Amino Acids via Human H+-Coupled Oligopeptide Transporter PEPT1

5-Aminosalicylic acid (5-ASA) is used as first line therapy for symptom remission and maintenance of inflammatory bowel disease (IBD). Because 5-ASA is well absorbed from the small intestine when orally administered, several 5-ASA formulations for selective delivery to the colon have been developed and used in clinical practice. However, its delivery efficiency to local inflamed colonic sites remains low. Intestinal H⁺-coupled oligopeptide transporter 1 (PEPT1) expression in the colon is low, whereas its expression is induced in the colon under chronic inflammation conditions, such as IBD. Therefore, we considered that PEPT1 would be a target transporter to improve 5-ASA delivery efficiency to local colonic lesions. We evaluated the transport characteristics of dipeptide-like 5-ASA derivatives, which were coupling glycine (Gly), lysine, glutamic acid (Glu), valine (Val) and tyrosine to amino or carboxyl group of 5-ASA, in Caco-2 cells. [³H]Glycylsarcosine (Gly-Sar) uptake into Caco-2 cells was inhibited by all 5-ASA derivatives. In addition, 5-ASA derivatives (Gly-ASA, Glu-ASA and Val-ASA), which were coupled by glycine, glutamic acid and valine to amino group of 5-ASA, were taken up in a pH- and concentration-dependent manner and their uptake was inhibited by excess Gly-Sar. Two-electrode voltage-clamp experiment using human PEPT1 expressing Xenopus oocytes showed that Gly-ASA, Glu-ASA and Val-ASA induced marked currents at pH 6.0. Taken together, these results showed that these 5-ASA derivatives are transportable substrates for PEPT1.

Liquid and Solid Self-Emulsifying Drug Delivery Systems (SEDDs) as Carriers for the Oral Delivery of Azithromycin: Optimization, In Vitro Characterization and Stability Assessment

Azithromycin (AZM) is a macrolide antibiotic used for the treatment of various bacterial infections. The drug is known to have low oral bioavailability (37%) which may be attributed to its relatively high molecular weight, low solubility, dissolution rate, and incomplete intestinal absorption. To overcome these drawbacks, liquid (L) and solid (S) self-emulsifying drug delivery systems (SEDDs) of AZM were developed and optimized. Eight different pseudo-ternary diagrams were constructed based on the drug solubility and the emulsification studies in various SEDDs excipients at different surfactant to co-surfactant (Smix) ratios. Droplet size (DS) < 150 nm, dispersity (Đ) ≤ 0.7, and transmittance (T)% > 85 in three diluents of distilled water (DW), 0.1 mM HCl, and simulated intestinal fluids (SIF) were considered as the selection criteria. The final formulations of L-SEDDs (L-F1(H)), and S-SEDDs (S-F1(H)) were able to meet the selection requirements. Both formulations were proven to be cytocompatible and able to open up the cellular epithelial tight junctions (TJ). The drug dissolution studies showed that after 5 min > 90% and 52.22% of the AZM was released from liquid and solid SEDDs formulations in DW, respectively, compared to 11.27% of the pure AZM, suggesting the developed SEDDs may enhance the oral delivery of the drug. The formulations were stable at refrigerator storage conditions.

Gut microbiota influence on oral bioaccessibility and intestinal transport of pesticides in Chaenomeles speciosa

There is limited research focusing on the effects of human gut microbiota on the oral bioaccessibility and intestinal absorption of pesticide residues in food. In the present study, we use a modified setup of the Simulator of the Human Intestinal Microbial Ecosystem for the determination of pesticide residue bioaccessibility in Chaenomeles speciosa, and a Caco-2 cell model of human intestinal absorption. Results showed that gut microbiota played a dual role based their effects on contaminant release and metabolism in the bioaccessibility assay, and Lactobacillus plantarum was one of key bacterial species in the gut microbiota that influenced pesticide stability significantly. The addition of L. plantarum to the system reduced the relative amounts (by 11.40-86.51%) of six pesticides. The interaction between the food matrix and human gut microbiota led to different absorption rates, and the barrier effects increased with an increase in incubation time.

Giardia duodenalis Induces Apoptosis in Intestinal Epithelial Cells via Reactive Oxygen Species-Mediated Mitochondrial Pathway In Vitro

The intestinal protozoan parasite, Giardia duodenalis, infects a large number of people in the world annually. Giardia infection has been considered a negative effect on intestinal epithelial cell growth, while the underlying mechanisms remain to be explored. Here we evaluated reactive oxygen species (ROS) production and apoptotic events in Giardia trophozoites-stimulated Caco-2 cells via fluorescence microscopy, transmission electron microscopy, flow cytometry, western blot, and cell counting kit-8 analyses. The results showed that Giardia trophozoite treatment could induce lactate dehydrogenase release and Caco-2 cell apoptosis. The ROS levels were increased post treatment. The observed typical characteristics of mitochondria damage include significant swelling and degeneration of matrix and cristae. After trophozoite treatment, the level of Bax protein expression was increased, while Bcl-2 protein decreased. Trophozoite stimulation also led to reduction of mitochondrial membrane potential and release of cytochrome c from the mitochondria to the cytoplasm, and this process was accompanied by activation of caspase-9 and caspase-3 and poly (ADP-ribose) polymerase 1 cleavage. Pretreatment with N-acetyl-L-cysteine, a ROS inhibitor, reversed G. duodenalis-induced Caco-2 cell apoptosis. Taken together, we indicated that G. duodenalis could induce Caco-2 cell apoptosis through a ROS- and mitochondria-mediated caspase-dependent pathway. This study furthers our understanding of the cellular mechanism of the interaction between Giardia trophozoites and host cells.

Development of Caco-2 cells expressing four CYPs via a mammalian artificial chromosome

Background

Oral administration is the most common way to deliver drugs to the systemic circulation or target organs. Orally administered drugs are absorbed in the intestine and metabolized in the intestine and liver. In the early stages of drug development, it is important to predict first-pass metabolism accurately to select candidate drugs with high bioavailability. The Caco-2 cell line derived from colorectal cancer is widely used as an intestinal model to assess drug membrane permeability. However, because the expression of major drug-metabolizing enzymes, such as cytochrome P450 (CYP), is extremely low in Caco-2 cells, it is difficult to predict intestinal metabolism, which is a significant factor in predicting oral drug bioavailability. Previously, we constructed a mouse artificial chromosome vector carrying the CYP (CYP2C9, CYP2C19, CYP2D6, and CYP3A4) and P450 oxidoreductase (POR) (4CYPs-MAC) genes and increased CYP expression and metabolic activity in HepG2 cells via transfer of this vector.

Results

In the current study, to improve the Caco-2 cell assay model by taking metabolism into account, we attempted to increase CYP expression by transferring the 4CYPs-MAC into Caco-2 cells. The Caco-2 cells carrying the 4CYPs-MAC showed higher CYP mRNA expression and activity. In addition, high metabolic activity, availability for permeation test, and the potential to assess drug–drug interactions were confirmed.

Conclusions

The established Caco-2 cells with the 4CYPs-MAC are expected to enable more accurate prediction of the absorption and metabolism in the human intestine than parental Caco-2 cells. The mammalian artificial chromosome vector system would provide useful models for drug development.

Peptide Release after Simulated Infant In Vitro Digestion of Dry Heated Cow's Milk Protein and Transport of Potentially Immunoreactive Peptides across the Caco-2 Cell Monolayer

Dry heating of cow’s milk protein, as applied in the production of “baked milk”, facilitates the resolution of cow’s milk allergy symptoms upon digestion. The heating and glycation-induced changes of the protein structure can affect both digestibility and immunoreactivity. The immunological consequences may be due to changes in the peptide profile of the digested dry heated milk protein. Therefore, cow’s milk protein powder was heated at low temperature (60 °C) and high temperature (130 °C) and applied to simulated infant in vitro digestion. Digestion-derived peptides after 10 min and 60 min in the intestinal phase were measured using LC-MS/MS. Moreover, digests after 10 min intestinal digestion were applied to a Caco-2 cell monolayer. T-cell epitopes were analysed using prediction software, while specific immunoglobin E (sIgE) binding epitopes were identified based on the existing literature. The largest number of sIgE binding epitopes was found in unheated samples, while T-cell epitopes were equally represented in all samples. Transport of glycated peptide indicated a preference for glucosyl lysine and lactosyl-lysine-modified peptides, while transport of peptides containing epitope structures was limited. This showed that the release of immunoreactive peptides can be affected by the applied heating conditions; however, availability of peptides containing epitopes might be limited.

Hypoglycemic effect of soluble polysaccharide and catechins from green tea on inhibiting intestinal transport of glucose

BACKGROUND

Water soluble polysaccharide derived from green tea (WSP) is produced as byproducts when catechins were extracted from green tea. Although inhibitory effect of green tea catechins on the glucose transport in small intestine has been studied, the hypoglycemic efficacy of the WSP or its combinational effect has not been studied. In order to investigate hypoglycemic efficacy of the WSP or its combinational effect with green tea extract (GTE), co-consumption of GTE and WSP with wheat starch was investigated using in vitro digestion coupled with Caco-2 cells. The mechanism of the intestinal glucose transport was elucidated throughout the gene expression of the intestinal glucose transporters, which included sodium dependent glucose transporter (SGLT1) and glucose transporter 2 (GLUT2), using quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

The co-digestion of wheat starch with GTE during the small intestinal phase was the most rapidly digested into reducing sugar (73.96 g L^-1 ) compared to itself (48.44 g L^-1 ), WSP (60.35 g L^-1 ), and GTE + WSP (61.81 g L^-1 ). Intestinal glucose transport was 11.82, 7.59, 4.49, and 2.40% for wheat starch, wheat starch with GTE, WSP, and GTE + WSP, respectively. The highest decreased expression pattern in SGLT1 was observed when cells treated with wheat starch + GTE + WSP (0.66-fold) compared to GTE or WSP treatment.

CONCLUSION

The results suggested that co-consumption of green tea derived products with wheat starch could delay the intestinal absorption of glucose. Results from the current study suggested that GTE and WSP could be the useful supplements of dietary therapy for hyperglycemia to delay glucose absorption. © 2020 Society of Chemical Industry.

Carboxymethyl β-cyclodextrin grafted carboxymethyl chitosan hydrogel-based microparticles for oral insulin delivery

This study was aimed at utilizing polysaccharides for the development of effective hydrogel microparticles for oral insulin delivery that has a controlled, and sustained release to enhance paracellular transcellular absorption. Carboxymethyl β-cyclodextrin grafted carboxymethyl chitosan hydrogels (CMCD-g-CMCs) were prepared from carboxymethyl β-cyclodextrin (CMCD) and carboxymethyl chitosan (CMC) using a water-soluble carbodiimide as a crosslinker in the presence of N-hydroxysuccinimide. After synthesis, the hydrogel structures were determined via FT-IR and XRD analyses. The porous structure of hydrogels was confirmed by SEM observations and swelling behaviours. The insulin release behaviours were found to betriggered by pH in vitro. Results showed that insulin was successfully retained inside the hydrogels in the gastric environment and slowly released following passage to intestinal conditions. The stability of the secondary structure of insulin was studied by dichroism circular (CD) and fluorescence (FL) spectrophotometer measurement. There was no significant difference in the secondary structure between the native and released insulin. In vitro studies revealed that the hydrogel microparticles exhibited non-cytotoxicity and were transported across the Caco-2 cell monolayers mainly via the paracellular pathway. In order to examine the effectiveness of hydrogel-based sustained release microparticles in delivering insulin in vivo, we administered different insulin-loaded hydrogel microparticles to diabetic mice. In these studies, we found that the insulin-loaded hydrogel microparticles provided a significant and sustained (ranging from 6 h to 12 h) reduction in the blood glucose levels of diabetic mice compared with subcutaneous injection. Overall, these findings demonstrate that CMCD-g-CMCs may be a promising protein carrier for use in oral drug delivery.