Aims: Lactococcus lactis is a non-colonizing, generally-regarded as safe (GRAS) lactic acid bacteria that has been frequently studied as a potential vector for bactofection. To mediate bactofection, a series of interaction between the bacteria and the host cell needs to occur. This study aims to investigate the in vitro bacterial-cell interaction between a locally-isolated L. lactis M4 strain with human colorectal cancer line, Caco-2. Methodology and results: Bacterial interaction was evaluated via adherence and internalisation assays. A 250:1 ratio of bacteria to cancer cell was selected as the optimum multiplicity of infection for all assays. After 2 h, L. lactis M4 was able to adhere to and internalise into Caco-2 cells at comparable rates to commercial strains L. lactis NZ9000 and MG1363. Conclusion, significance and impact of study Findings from this study showed that this strain has similar interaction properties with the commercial strains and would make a promising candidate for future bactofection studies and development of bacteria-mediated DNA vaccination against various diseases.
Lactococcus lactis ; Colorectal Neoplasms ; Caco-2 Cells

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.
Caco-2 Cells ; Drugs, Chinese Herbal ; Emulsions ; Humans ; Isoflavones ; Nanoparticles

OBJECTIVETo establish and assess the Caco-2 cell in vitro absorption model.

METHODSCaco-2 cells were cultured on the millipore filters fixed in Snapwell transport chamber. The cell morphology, transepithelial electrical resistance, mannitol efflux rate and alkaline phosphatase activities were monitored during culture.

RESULTSAfter 21 days of in vitro culture, formation of tight junction was observed between the cells. The transepithelial electrical resistance reach a relatively stable value of 620-/+47 Omega.cm(2), the mannitol efflux rate was lower than 0.3%.h(-1).cm(-2), and the alkaline phosphatase activity in the apical side was significantly higher than that in the basolateral side.

CONCLUSIONThe established Caco-2 cell model shows similar morphology to intestinal epithelial cells with formation of polarity, and can be used as an in vitro model for absorption studies.

Caco-2 Cells ; Cell Culture Techniques ; methods ; Epithelial Cells ; cytology ; metabolism ; Humans ; Intestinal Absorption ; Intestines ; cytology

Shuxiong prescription (Notoginseng Radix et Rhizoma, Chuanxiong Rhizome and Carthami Flos) has the function of activating blood circulation to dissipate blood stasis, activating meridians to stop pain. This paper was mainly aimed to discuss the transport characteristics of Shuxiong prescription across Caco-2 cell monolayer. Safe concentration range of Shuxiong prescription against Caco-2 cell monolayer model was determined by MTT assay. The mechanism of Shuxiong prescription bidirectional transport was investigated by Caco-2 cell monolayer model. The apparent permeability coefficient Papp of digoxin was determined by high performance liquid chromatography (HPLC). The test results showed that the Papp of extract from Notoginseng Radix et Rhizoma, Chuanxiong Rhizome, Carthami Flos, Chuanxiong Rhizome+Carthami Flos and Shuxiong prescription transport from apical (AP) side to basolateral (BL) side was (3.12±0.73)×10⁻⁶, (2.58±0.41)×10⁻⁶, (4.97±0.64)×10⁻⁶, (4.63±0.57)×10⁻⁶, (5.79±0.68)×10⁻⁶ cm·s⁻¹, respectively, indicating that the transport of digoxin across Caco-2 cell monolayer model was active absorption, and the P-gp protein took part in the process. Chuanxiong Rhizome could significantly decrease the transport of digoxin from BL→AP(<0.01) and increase its transport from AP→BL(<0.05) significantiy. After the addition of Shuxiong prescription, the transport of digoxin from BL→AP was significantly inhibited(<0.01). The results suggested that the extract of safflower had no effect on P-gp transport, nor on the independence diffusion of digoxin. The transport of digoxin could be degraded by the extract of Chuanxiong Rhizome and the extract of Shuxiong prescription from BL→AP(<0.01), significantly; pseudo-ginseng had no effect on the independence diffusion of digoxin; the extract of safflower+Chuanxiong Rhizome had the same experimental result as Chuanxiong Rhizome extract.
Biological Transport ; Caco-2 Cells ; Chromatography, High Pressure Liquid ; Digoxin ; pharmacokinetics ; Drugs, Chinese Herbal ; pharmacokinetics ; Humans

In this study, we studied the solubility and permeability of matrine, oxymatrine, sophoridine, and oxysophocarpine, four alkaloids in the Mongolian herbal medicine Sophorae Flavescentis Radix, and evaluated the absorption mechanism with the Caco-2 cell model, so as to provide a basis for the new drug development and efficacy evaluation of Sophorae Flavescentis Radix. The results showed that all the four alkaloids had high solubility and high permeability and can be well absorbed, belonging to the class-I drugs of Biopharmaceutical Classification System(BCS). The absorption(AP→BL) and excretion(BL→AP) of matrine and oxymatrine were not affected by the concentration while the absorption depended on P-gp protein. The absorption(AP→BL) and excretion(BL→AP) of sophoridine and oxysophocarpine were positively related to the concentration and time, and the absorption process was independent from P-gp protein. The results provide scientific reference and an experimental basis for the development of Mongolian medical prescriptions containing Sophorae Flavescentis Radix.
Alkaloids ; Biological Products ; Caco-2 Cells ; Drugs, Chinese Herbal ; Herbal Medicine ; Humans ; Sophora

The absorption is the key to the resulted efficacy of orally administered drugs and the small intestine is the main site to absorb the orally administered drug. In this paper, internationally recognized human colon adenocarcinoma cell line(Caco-2) monola-yer model which can simulate small intestinal epithelial cell was used to comparatively study the absorption and transportation diffe-rences of total coumarins and main individual coumarin in Angelica dahurica 'Yubaizhi' by separately using 6-and 12-well plates. It was found that apparent permeability coefficient(P_(app)) values of oxypeucedanin hydrate, byakangelicin and phellopterin were at the quantitative degree of 1 × 10~(-5) cm·s~(-1) when the individual administration was conducted independently, indicating that they were well-absorbed compounds. P_(app) ratio of their bi-directional transportation was close to 1, indicating that they can be absorbed across Caco-2 monolayer by passive diffusion mechanism without carrier mediation during the transportation. The similar trend of transportation was also observed for imperatorin, isoimperatorin and bergapten. The P_(app) values of oxypeucedanin hydrate, byakangelicin and bergapten were at quantitative degree of 1 × 10~(-5) cm·s~(-1) when the administration of total coumarins in Angelica dahurica 'Yubaizhi' was conducted, indicating that they were well-absorbed compounds. The results were consistent with those of independent administration of individual coumarins. Whereas, the P_(app) values of imperatorin, phellopterin and isoimperatorin in the total coumarins decreased, indicating that the interaction between compounds may exist although the P_(app) value ratio of bi-directional transportation was between 0.5 and 1.5. The results laid the foundation for intestinal absorption study of Angelica dahurica 'Yubaizhi' coumarins in compound Chinese medicine.
Angelica ; Caco-2 Cells ; Coumarins ; Drugs, Chinese Herbal ; Humans ; Intestinal Absorption ; Plant Roots

To investigate the effect and mechanism of metformin on intestinal epithelial barrier injury in ulcerative colitis. A cell model of colitis was established by co-culture of human colon cancer cell line Caco-2 and human monocyte cell line THP-1. The colitis model cells were treated with metformin at concentration of for Flow cytometry was used to detect Caco-2 cell apoptosis, and Western blotting was used to detect the protein expression of tight junction proteins and endoplasmic reticulum stress-related proteins. After metformin treatment, the apoptosis rate of Caco-2 cells was decreased from (14.22±2.34)% to 0.61)% (=3.119, <0.05), and the expression levels of tight junction protein-1 and claudin-1 increased (=5.172 and 3.546, both <0.05). In addition, the expression levels of endoplasmic reticulum-related proteins glucose regulated protein (GRP) 78, C/EBP homologous protein (CHOP) and caspase-12, as well as the phosphorylation level of PRKR-like endoplasmic reticulum kinase (PERK) and eukaryotic translation initiation factor 2α (eIF2α) decreased (all <0.05). Metformin may alleviate the intestinal epithelial barrier damage in colitis by reducing intestinal epithelial cell apoptosis and increasing the expression of tight junction proteins, which may be associated with the inhibition of endoplasmic reticulum stress-induced apoptotic pathway.
Apoptosis ; Caco-2 Cells ; Colitis, Ulcerative ; Endoplasmic Reticulum Stress ; Humans ; Metformin/pharmacology*

OBJECTIVE: To explore the expression profiling of circRNAs in ulcerative colitis(UC) and then determine the significantly changed circRNA and its influences on intestinal epithelial barrier. METHODS: In this study, we selected 5 pairs of inflamed and normal colorectal mucosa tissues from UC patients to perform circRNAs microarray and identified the differentially expressed circRNAs in the UC inflamed colorectal mucosa tissues, and quantitative real-time PCR was used to identify the expression change of circ-SOD2 in 30 UC patients' inflamed and normal colorectal mucosa tissues. We detected the expression of circ-SOD2 in Caco2 and NCM460 cells after being treated with inflammatory factors (LPS, TNF-α, IL1-β). Fluorescence in situ hybridization (FISH) was used to determine the cellular location of circ-SOD2 in the UC colorectal mucosal tissues. The circ-SOD2 overexpression vector was constructed and produced and then transfected into Caco2 cells to examine the cells' trans-epithelial electrical resistance (TEER), permeability of FITC-dextran and the alterations of epithelial barrier related molecules. RESULTS: We found 264 circRNAs (111 increased and 153 decreased) differentially expressed in the inflamed colon mucosa compared with normal colon mucosa using a P-value <0.05 and a >1.5-fold change cutoff. To validate the circRNA microarray results, we selected some circRNAs to perform qRT-PCR based on the following criteria: (1) circRNAs raw data >100 in each sample, (2) fold-change >2, (3) P<0.05. We identified 10 dysregulated circRNA, among them, circ-SOD2 was upregulated with maximum fold-change in the UC inflamed colorectal mucosa tissues. Then we identified circ-SOD2 was upregulated significantly through quantitative real-time PCR (qRT-PCR) in expanded 30 paired colorectal mucosa tissues(P<0.001). After treatments with LPS, TNF-α and IL1-β, circ-SOD2 was upregulated in Caco2 and NCM460 cells at different points from 1 to 7 h. Fluorescence in situ hybridization (FISH) indicated that circ-SOD2 located in intestinal epithelium mostly and few in mesenchyme and inflammatory cells. The overexpression of circ-SOD2 in Caco2 cells resulted in a decrease of transepithelial electrical resistance (TEER), an increase of the FITC-dextran permeability and the downregulation of epithelial barrier related molecule CLDN-8 (P<0.05). CONCLUSION The dysregulation of circRNAs existed in UC inflamed colorectal mucosa, among which, the upregulated circ-SOD2 weakened the intestinal epithelial barrier and thus might promote the occurrence of ulcerative colitis.
Caco-2 Cells ; Colitis, Ulcerative ; Humans ; In Situ Hybridization, Fluorescence ; RNA ; Superoxide Dismutase/metabolism*

Objective: To analyze the effects of spvD gene on invasion and intracellular proliferation of Caco-2 cells and in order to provide insight into the function of that gene and the underlying mechanism of Salmonella caused infection. Methods: Functional verification of spvD gene deletion mutant and compensation strain. The deletion mutant strain was constructed through a suicide plasmid-mediated homologous recombination. The compensation plasmid constructed by cloning the coding sequence of spvD by PCR into plasmid pBAD33 was mobilized into the deletion mutant by conjugation and the pBAD33 was introduced into wild strains and deleted mutant strains as control. The relative expression of spvD mRNA was detected by quantitative reverse transcription PCR. In order to analyze the virulence of spvD against Caco-2 cells, Caco-2 cells was cocultured with wild type Salmonella enteritidis carrying spvD gene, the deletion mutant strain and compensation strain respectively. The expression level of spvD mRNA and the the number of Salmonella enteritidis after Caco-2 cells intervention were compared between the three groups by LSD-t test, and the invasion rate was compared by χ² test. Results: The expression level of spvD mRNA in wild type Salmonella enteritidis was set as unit "1", the deletion mutant strain was "0.00", and the compensation strain was "2.60" (LSD-t_{wild, deleted}=1.11, P=0.31; LSD-t_{wild, compensation}=-1.77, P=0.13; LSD-t _{deleted, compensation}=-2.88, P=0.03), which confirmed the successful construction of the deletion mutant strain and the compensation strain. The invasion experiment results of the above three Salmonella enteritidis strains on Caco-2 cells showed that the invasion rate of wild strain was 0.23%, the invasion rate of deleted mutant strain was 0.16%, and the invasion rate of compensation strain was 0.16%, with no statistical significance (χ²=1.13, P=0.570). By comparing the number of Salmonella enteritidis at different time points after Caco-2 cells intervention, it was discovered that the number of Salmonella enteritidis in wild strains (6.50×10⁶ CFU/ml) and compensation strains (7.25×10⁶ CFU/ml) was significantly increased than that in deletion mutant strain (1.90×10⁶ CFU/ml) after 16 h coculture (LSD-t_{wild, deleted}=7.95, P=0.00; LSD-t_{wild, compensation}=-1.27, P=0.25; LSD-t _{deleted, compensation}=-9.22, P=0.00). Conclusion: It is not considered that spvD gene can affect the invasion of Salmonella enteritidis on Caco-2 cells, but the gene can promote the reproduction of Salmonella enteritidis in Caco-2 cells.
Caco-2 Cells ; Gene Deletion ; Humans ; Lysergic Acid Diethylamide ; RNA, Messenger/genetics* ; Salmonella enteritidis/genetics*

OBJECTIVETo investigate the role of cyclic adenosine monophosphate(cAMP) in the regulation of intestinal epithelial barrier function under hypoxia.

METHODSIntestinal epithelial barrier was established by Caco-2 monolayers. Cells were divided into four groups: normoxia (Nx), normoxia plus Forskolin(Nx+FSK), hypoxia(Hx), hypoxia plus SQ22536(Hx+SQ22536). cAMP concentrations of different groups were assessed by cAMP enzyme immunoassay kit. RT-PCR and Western blotting were used to detect the mRNA and protein expressions of claudin-1 and occludin under normoxic and hypoxic condition. Caco-2 monolayers were grown on Millicell filters, and transepithelial electrical resistance(TER) was measured using a Millipore electric resistance system.

RESULTSThe concentration of cAMP under hypoxic conditions(Hx group) was higher compared with Nx group [(6.30±0.50) pmol/L vs. (2.38±0.18) pmol/L, P<0.01]. At the same time, both mRNA and protein expressions of claudin-1 and occluding were lower in Hx group than those in Nx group(all P<0.05). TER decreased by 76.30±0.64(P<0.01). When the monolayers were exposed to hypoxia plus SQ22536 (Hx+SQ22536 group), the concentration of cAMP was(2.12±0.23) pmol/L, which was lower than that under hypoxic conditions(Hx group, P<0.01). Both mRNA and protein expressions of claudin-1 and occludin were higher compared to Hx group (all P<0.01). TER increased by 32.96±2.16 (P<0.05).

CONCLUSIONWhen Caco-2 cells are exposed to hypoxia, barrier function, claudin-1 and occludin expression are diminished in parallel with a high level of intracellular cAMP compared with the normoxic condition. Inhibition of the intracellular cAMP level under hypoxia can maintain the intestinal epithelial function through regulating the claudin-1 and occludin expression and attenuate the permeability of intestinal mucosa.

Adenosine Monophosphate ; Caco-2 Cells ; Claudin-1 ; metabolism ; Humans ; Intestinal Mucosa ; metabolism ; Intestines ; Occludin ; metabolism