Human Intestinal Permeability Research Articles

High-Throughput SFC-MS/MS Method to Measure EPSA and Predict Human Permeability.

Permeability is a key factor driving the absorption of orally administered drugs. In early discovery, the efficient evaluation of permeability, particularly for compounds violating Lipinski's Rule of 5, remains challenging. Addressing this, we established a high-throughput method to measure the experimental polar surface area (HT-EPSA) as an in vitro surrogate to measure permeability. Compared to earlier methods, HT-EPSA significantly reduces data acquisition time with enhanced sensitivity, selectivity, and data quality. In the effort of translating EPSA to human in vitro and in vivo passive permeability, we demonstrated the application of EPSA for predicting Caco-2 cell and human intestinal permeability, showing improvements over topological polar surface area and the parallel artificial membrane permeability assay for rank-ordering permeability in a proteolysis targeting chimera case study. The HT-EPSA method is expected to be highly beneficial in guiding early stage compound rank-ordering, faster decision-making, and in predicting in vitro and/or in vivo human intestinal permeability.

Genetic and Phenotypic Characterization of Bacillus velezensis Strain BV379 for Human Probiotic Applications.

Bacterial spore-forming Bacillaceae species, including Bacillus subtilis and Heyndrickxia coagulans, are increasingly utilized for probiotic dietary supplementation. Bacillus velezensis is a Bacillus species that is frequently used as a direct-fed microbial in animal feed but less so as a probiotic for humans. The objective of this study was to characterize the suitability of the Bacillus velezensis strain BV379 for probiotic applications by (1) in silico screening for both adverse genetic elements and putatively beneficial traits, (2) in vitro evaluation of interactions with human intestinal epithelial cells, and (3) in vitro characterization of BV379 spore viability at various temperatures, pH, and in the presence of bile salt. In silico screening of the BV379 genome revealed few genes encoding Bacillaceae-associated toxins, virulence factors, and enzymes involved in the production of toxins. While BV379 encodes five antimicrobial resistance genes, minimum inhibitory concentration assays determined that BV379 is susceptible to all eight clinically relevant antibiotics tested. Preliminary cell culture experiments showed that BV379 lysates did not adversely impact human intestinal epithelial cell viability and monolayer permeability. It was also determined that BV379 spores can easily tolerate the harsh pH, bile salt, and microaerobic conditions typical of the GI tract. Altogether, the results presented herein support the safety and potential of Bacillus velezensis strain BV379 for use as an oral probiotic.

First-in-Human Assessment of Gut Permeability in Crohn’s Disease Patients Using Fluorophore Technology

Background and AimsThe dual sugar absorption test (DSAT) as a classic measure of human intestinal permeability has limited clinical utility due to lengthy and cumbersome urine collection, assay variability, and long turnaround. We aimed to determine if the orally administered fluorophore MB-102 (relmapirazin) (MW=372) compares to lactulose (L) (MW=342) and rhamnose (R) (MW=164)-based DSAT as a measure of gut permeability in people with a spectrum of permeability including those with Crohn’s disease (CD). MethodsWe performed a single center, randomized, open label, crossover study comparing orally administered MB-102 (1.5 or 3.0 mg/kg) to L (1000 mg) and R (200 mg). Adults with active small bowel CD on magnetic resonance enterography (cases) and healthy adults (controls) were randomized to receive either MB-102 or L and R on study day 1, and the other tracer 3-7 days later. Urine was collected at baseline and 1, 2, 4, 6, 8, 10, and 12 hours after tracer ingestion to calculate the cumulative urinary percent excretion of MB-102 and L and R. ResultsNine cases and 10 controls completed the study without serious adverse events. Urinary recovery of administered MB-102 correlated with recovery of lactulose (r-squared = 0.83) for all participants. MB-102 urine recovery also tracked with the L:R ratio urine recovery (r-squared=0.57). In controls, the percentages of L and MB-102 recovered were similar within a narrow range unlike in CD patients. ConclusionsThis first-in-human study of an orally administered fluorophore to quantify gastrointestinal permeability in adults with CD demonstrates that MB-102 is well tolerated, and its recovery in urine mirrors that of percent L and the L:R ratio.

Simultaneous Prediction Method for Intestinal Absorption and Metabolism Using the Mini-Ussing Chamber System.

Many evaluation tools for predicting human absorption are well-known for using cultured cell lines such as Caco-2, MDCK, and so on. Since the combinatorial chemistry and high throughput screening system, pharmacological assay, and pharmaceutical profiling assay are mainstays of drug development, PAMPA has been used to evaluate human drug absorption. In addition, cultured cell lines from iPS cells have been attracting attention because they morphologically resemble human intestinal tissues. In this review, we used human intestinal tissues to estimate human intestinal absorption and metabolism. The Ussing chamber uses human intestinal tissues to directly assay a drug candidate's permeability and determine the electrophysiological parameters such as potential differences (PD), short circuit current (Isc), and resistance (R). Thus, it is an attractive tool for elucidating human intestinal permeability and metabolism. We have presented a novel prediction method for intestinal absorption and metabolism by utilizing a mini-Ussing chamber using human intestinal tissues and animal intestinal tissues, based on the transport index (TI). The TI value was calculated by taking the change in drug concentrations on the apical side due to precipitation and the total amounts accumulated in the tissue (Tcorr) and transported to the basal side (Xcorr). The drug absorbability in rank order, as well as the fraction of dose absorbed (Fa) in humans, was predicted, and the intestinal metabolism of dogs and rats was also predicted, although it was not quantitative. However, the metabolites formation index (MFI) values, which are included in the TI values, can predict the evaluation of intestinal metabolism and absorption by using ketoconazole. Therefore, the mini-Ussing chamber, equipped with human and animal intestinal tissues, would be an ultimate method to predict intestinal absorption and metabolism simultaneously.

Biomimetic Dispersive Solid-Phase Microextraction: A Novel Concept for High-Throughput Estimation of Human Oral Absorption of Organic Compounds.

There is a quest for a novel in vitro analytical methodology that is properly validated for the prediction of human oral absorption and bioaccumulation of organic compounds with no need of animal models. The traditional log P parameter might not serve to predict bioparameters accurately inasmuch as it merely accounts for the hydrophobicity of the compound, but the actual interaction with the components of eukaryotic cells is neglected. This contribution proposes for the first time a novel biomimetic microextraction approach capitalized on immobilized phosphatidylcholine as a plasma membrane surrogate onto organic polymeric sorptive phases for the estimation of human intestinal effective permeability of a number of pharmaceuticals that are also deemed contaminants of emerging concern in environmental settings. A comprehensive exploration of the conformation of the lipid structure onto the surfaces is undertaken so as to discriminate the generation of either lipid monolayers or bilayers or the attachment of lipid nanovesicles. The experimentally obtained biomimetic extraction data is proven to be a superb parameter against other molecular descriptors for the development of reliable prediction models of human jejunum permeability with R2 = 0.76, but the incorporation of log D and the number of aromatic rings in multiple linear regression equations enabled improved correlations up to R2 = 0.88. This work is expected to open new avenues for expeditious in vitro screening methods for oral absorption of organic contaminants of emerging concern in human exposomics.

Improvement of Workflows and Assay Reproducibility by The Introduction of "Assay-Ready" Culturing of MDCK Cells for Transport Studies.

In previous studies, we established and validated three Madin Darby Canine Kidney MDCKII cell lines, recombinantly modified with zinc finger nuclease (ZFN) technology. Here, we investigated the applicability of seeding these three canine P-gp deficient MDCK_ZFN cell lines, directly from frozen cryopreserved stocks without previous cultivation for efflux transporter and permeability studies. This technique is referred to as "assay-ready" and allows for highly standardized conduction of cell-based assays and shorter cultivation cycles. To obtain a rapid fitness of the cells for that purpose, a very gentle freezing and thawing protocol was applied. Assay-ready MDCK_ZFN cells were tested in bi-directional transport studies and compared to their traditionally cultured counterparts. Long-term performance robustness, human effective intestinal permeability (Peff) predictability and batch to batch variability were assessed. Efflux ratios (ER) and apparent permeability (Papp) results were highly comparable between assay-ready and standard cultured cell lines with R2 values of 0.96 or higher. Papp to Peff correlations obtained from passive permeability with non-transfected cells were comparable independent of the cultivation regime. Long-term evaluation revealed robust performance of assay-ready cells and reduced data variability of reference compounds in 75% of cases compared to standard cultured MDCK_ZFN cells. Assay-ready methodology for handling MDCK_ZFN cells allows more flexibility in assay planning and reduces performance fluctuations in assays caused by cell aging. Therefore, the assay-ready principle has proven superior over conventional cultivation for MDCK_ZFN cells and is considered as a key technology to optimize processes with other cellular systems.

Design and rationale for the SIB trial: a randomized parallel comparison of semaglutide versus placebo on intestinal barrier function in type 2 diabetes mellitus

Objective: To describe the rationale and design of the SIB trial, an interventional clinical trial testing the hypothesis that subcutaneous (s.c.) once-weekly semaglutide can improve intestinal permeability and reduce systemic inflammation in participants with type 2 diabetes (T2D) and obesity. Methods: SIB (NCT04979130) is an investigator-initiated, single-center randomized, double-blinded, placebo-controlled clinical study being conducted at the University of Colorado Anschutz Medical Campus. The primary objective of this novel trial is to test the hypothesis that subcutaneous (s.c.) once-weekly semaglutide could improve intestinal permeability and reduce systemic inflammation in participants with T2D and obesity. Eligible participants had a diagnosis of type 2 diabetes, elevated body mass index, and evidence of systemic inflammation. Participants were randomized 1:1 to s.c. semaglutide or placebo. Participants were assessed for intestinal permeability and markers of inflammation at baseline, mid-study, and at the end of the study. Efficacy assessments were based on the analysis of the following: lactulose:mannitol ratio test, serum lipopolysaccharide-binding protein (LBP), fecal calprotectin, inflammatory biomarkers (IL-6, TNF, IL-1, IL-8, hs-CRP), and HbA1c. All participants who enrolled in the trial provided written informed consent after having received written and oral information on the trial. The risks of semaglutide use were minimized by administration according to FDA-labeled use and close monitoring for adverse events. Discussion: SIB is the first study to examine the effects of GLP-1 receptor agonists on intestinal permeability in humans and will provide important data on their impact on systemic inflammation and intestinal permeability in the setting of T2D and obesity.

From mouth to gut: microfluidic in vitro simulation of human gastro-intestinal digestion and intestinal permeability.

Reproducible in vitro studies of bioaccessibility, intestinal absorption, and bioavailability are key to the successful development of novel food ingredients or drugs intended for oral administration. There is currently a lack of methods that offer the finesse required to study these parameters for valuable molecules typically found in small volumes - as is the case of nanomaterials, which are often used to carry and protect bioactives. Here, we describe a modular microfluidic-based platform for total simulation of the human gastro-intestinal tract. Digestion-chips and cell-based gut-chips were fabricated from PDMS by soft lithography. On-chip digestion was validated using a fluorescently labelled casein derivative, which followed typical Michaelis-Menten kinetics and showed temporal resolution and good agreement with well-established bench-top protocols. Irreversible inhibition of serine proteases using Pefabloc® SC and a 1 : 6 dilution was sufficient to mitigate the cytotoxicity of simulated digestion fluids. Caco-2/HT29-MTX co-cultures were grown on-chip under a continuous flow for 7 days to obtain a differentiated cell monolayer forming a 3D villi-like epithelium with clear tight junction formation, and with an apparent permeability (Papp) of Lucifer Yellow closely approximating values reported ex vivo (3.7 × 10-6 ± 1.4 × 10-6vs. 4.0 × 10-6 ± 2.2 × 10-6). Digesta from the digestion-chips were flowed through the gut-chip, demonstrating the capacity to study sample digestion and intestinal permeability in a single microfluidic platform holding great promise for use in pharmacokinetic studies.

Human milk oligosaccharide disialyllacto-n-tetraose protects human intestinal epithelium integrity and permeability against mast cell chymase-induced disruption by stabilizing ZO-1/FAK/P38 pathway of intestinal epithelial cell

Context Inflammatory bowel disease (IBD) is a chronic gut disease with intestinal-epithelium disruption. Mast cell (MC) has been discussed in IBD studies, but its subset MCTC (chymase/tryptase) and MC-chymase have not been well-explored extensively. Human-milk-oligosaccharide-Disialyllacto-N-Tetraose (DSLNT) was reported as an effective strategy to protect infants against IBD with unclear mechanism. Objective This study was to examine the distribution of chymase-positive mast cells in the intestinal-epithelium-tissue of IBD infants, to explore the MC-chymase function on intestinal-epithelium, and to investigate the influences of DSLNT against MC-chymase-induced disruptions. Materials and Methods The intestinal-biopsies (surgical-waste) of the infants with IBD or with intestinal-atresia (non-IBD) were paraffin-embedded for immunohistochemistry. In-situ intestinal-tissue model and in-vitro human-intestinal-epithelial-cell (Caco-2) model were established with or without the treatments of MC-chymase (50mU/mL), DSLNT (600 µM) and DSLNT + MC-chymase respectively. The tissue morphology analysis, cell proliferation assay, cell-gap-closure assessment, fluorescence-immunocytochemistry, western blot, trans-epithelial-electrical-resistance, cell-cycle and statistical analysis were applied. Results There was an increased number of MCTC subset around the inflamed intestinal area in-vivo; MC-chymase caused intestinal-epithelial-barrier damage in-situ, decreased trans-epithelial-electrical-resistance of caco-2 cell monolayer in-vitro; while DSLNT protected epithelium against MC-chymase induced disruptions. MC-chymase reduced cell-viability, proliferation and migration, altered cell-cycle, down-regulated ZO-1, FAK, and P38 expressions, while DSLNT protected cells by impairing MC-chymase-induced interruptions. DSLNT can rescue ZO-1, FAK and P38 expressions and restore epithelial-cell integrity and cell cycle. Conclusions Chymase-positive MCs are involved in IBD progress. MC-chymase disrupts intracellular ZO-1/FAK/P38 signal pathway and cell-cell/cell-matrix contacts, while DSLNT protects intestinal-epithelium against MC-chymase to maintain the intestinal epithelium integrity.

Intestinal Barrier Permeability in Obese Individuals with or without Metabolic Syndrome: A Systematic Review.

Altered intestinal barrier permeability has been associated with obesity and its metabolic and inflammatory complications in animal models. The purpose of this systematic review is to assess the evidence regarding the association between obesity with or without Metabolic Syndrome (MetS) and alteration of the intestinal barrier permeability in humans. A systematic search of the studies published up until April 2022 in Latin America & Caribbean Health Sciences Literature (LILACS), PubMed, Scopus, Embase, and ScienceDirect databases was conducted. The methodological quality of the studies was assessed using the Newcastle–Ottawa scale (NOS) and the Agency for Healthcare Research and Quality (AHRQ) checklist. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework was used to assess the quality of the evidence. Eight studies were included and classified as moderate to high quality. Alteration of intestinal barrier permeability was evaluated by zonulin, lactulose/mannitol, sucralose, sucrose, lactulose/L-rhamnose, and sucralose/erythritol. Impaired intestinal barrier permeability measured by serum and plasma zonulin concentration was positively associated with obesity with MetS. Nonetheless, the GRADE assessment indicated a very low to low level of evidence for the outcomes. Thus, clear evidence about the relationship between alteration of human intestinal barrier permeability, obesity, and MetS was not found.

Present and Future Therapeutic Approaches to Barrier Dysfunction.

There is converging and increasing evidence, but also uncertainty, for the role of abnormal intestinal epithelial barrier function in the origin and development of a growing number of human gastrointestinal and extraintestinal inflammatory disorders, and their related complaints. Despite a vast literature addressing factors and mechanisms underlying changes in intestinal permeability in humans, and its connection to the appearance and severity of clinical symptoms, the ultimate link remains to be established in many cases. Accordingly, there are no directives or clinical guidelines related to the therapeutic management of intestinal permeability disorders that allow health professionals involved in the management of these patients to carry out a consensus treatment based on clinical evidence. Instead, there are multiple pseudoscientific approaches and commercial propaganda scattered on the internet that confuse those affected and health professionals and that often lack scientific rigor. Therefore, in this review we aim to shed light on the different therapeutic options, which include, among others, dietary management, nutraceuticals and medical devices, microbiota and drugs, and epigenetic and exosomes-manipulation, through an objective evaluation of the scientific publications in this field. Advances in the knowledge and management of intestinal permeability will sure enable better options of dealing with this group of common disorders to enhance quality of life of those affected.

From celiac disease to coccidia infection and vice-versa: The polyQ peptide CXCR3-interaction axis.

Zonulin is a physiological modulator of intercellular tight junctions, which upregulation is involved in several diseases like celiac disease (CeD). The polyQ gliadin fragment binds to the CXCR3 chemokine receptor that activates zonulin upregulation, leading to increased intestinal permeability in humans. Here, we report a general hypothesis based on the structural connection between the polyQ sequence of the immunogenic CeD protein, gliadin, and enteric coccidian parasites proteins. Firstly, a novel interaction pathway between the parasites and the host is described based on the structural similarities between polyQ gliadin fragments and the parasite proteins. Secondly, a potential connection between coccidial infections as a novel environmental trigger of CeD is hypothesized. Therefore, this report represents a promising breakthrough for coccidian research and points out the potential role of coccidian parasites as a novel trigger of CeD that might define a preventive strategy for gluten-related disorders in general. Also see the video abstract here: https://youtu.be/oMaQasStcFI.

Loss of PTPN2 in Intestinal Epithelial Cells Increases Invasion of Human Intestinal Epithelial Cells and Intestinal Permeability in Mice by Adherent‐invasive E. coli

Background : Alterations in epithelial tight junction proteins can compromise its ability to act as a barrier between luminal contents and underlying tissues, thereby increasing intestinal permeability, an early event in inflammatory bowel disease (IBD). Additionally, shifts in the gut microbiota and expansion of pathobionts such as adherent-invasive Escherichia coli (AIEC) are associated with the pathogenesis of IBD. Mice deficient in expression of the IBD gene candidate, Ptpn2,exhibit increased intestinal permeability and a pronounced expansion of a novel murine adherent-invasive Escherichia coli (mAIEC). This study aimed to investigate how PTPN2 expression in intestinal epithelial cells modifies mAIEC invasiveness and host-barrier properties after infection using in vitro and in vivo models. Methods First, we generated a fluorescent-tagged mAIEC strain — mAIECred. Caco-2BBe intestinal epithelial cells (IEC), stably expressing either scrambled shRNA or shRNA against Ptpn2, were infected with mAIECred. Tamoxifen-inducible, intestinal epithelial cell-specific knockout mice (Ptpn2∆IEC) and control littermates (Ptpn2fl/fl) were infected with either PBS, E. coli K12 or mAIECred. FITC-Dextran (FD4) and Rhodamine-Dextran (RD70) permeability probes were administered by oral-gavage. Post-necropsy, bacterial colonies were enumerated from mouse tissues. Results First we tested if PTPN2 deficiency in human IEC altered mAIECred invasion. Immunofluorescence showed that PTPN2 knockdown (KD) IECs exhibited increased bacterial invasion compared to control IECs (n=3). To confirm our results in an in vivo model, we infected Ptpn2∆IEC mice with either E. coli K12 or mAIECred or administered PBS as vehicle control. E. coli K12 increased FD4 but not RD70 permeability in Ptpn2∆IEC mice compared with Ptpn2fl/fl mice (P=0.0025; n=5-9) while mAIECred caused an even greater increase in FD4 permeability in Ptpn2∆IEC vs. Ptpn2fl/fl mice (P< 0.0001; n=6-9). Ptpn2∆IEC mice also exhibited higher mAIECred - but not K12 - bacterial load in distal colon tissue compared to Ptpn2fl/fl mice (P=0.038; n=9-12). As FD4 permeability was increased in Ptpn2∆IEC mice infected with K12 and mAIECred, we wanted to determine if this corresponded with changes in expression of relevant tight junction proteins. Western blot analysis from isolated IEC's revealed Ptpn2∆IEC mice infected with mAIECred had decreased E-cadherin (P=0.0142; n=4) and Occludin (P=0.0030; n=4). Conversely, we observed increased Claudin-2 in PBS and K12-infected Ptpn2∆IEC vs. Ptpn2fl/fl mice (P=0.015; n=4). mAIECred increased Claudin-2 levels above control(s) to comparable levels in Ptpn2fl/fl and Ptpn2∆IEC mice (P= 0.025; n=4). Conclusion Intestinal epithelial PTPN2 is critical in maintaining intestinal homeostasis by restricting bacterial invasion and preserving intestinal barrier function. Given that loss of PTPN2 in vivo also provokes expansion of AIEC, these studies indicate that PTPN2 is an important mediator of host-microbiome crosstalk.

A Novel Microphysiological Colon Platform to Decipher Mechanisms Driving Human Intestinal Permeability

Background & AimsThe limited availability of organoid systems that mimic the molecular signatures and architecture of human intestinal epithelium has been an impediment to allowing them to be harnessed for the development of therapeutics as well as physiological insights. We developed a microphysiological Organ-on-Chip (Emulate, Inc, Boston, MA) platform designed to mimic properties of human intestinal epithelium leading to insights into barrier integrity.MethodsWe combined the human biopsy-derived leucine-rich repeat-containing G-protein–coupled receptor 5–positive organoids and Organ-on-Chip technologies to establish a micro-engineered human Colon Intestine-Chip (Emulate, Inc, Boston, MA). We characterized the proximity of the model to human tissue and organoids maintained in suspension by RNA sequencing analysis, and their differentiation to intestinal epithelial cells on the Colon Intestine-Chip under variable conditions. Furthermore, organoids from different donors were evaluated to understand variability in the system. Our system was applied to understanding the epithelial barrier and characterizing mechanisms driving the cytokine-induced barrier disruption.ResultsOur data highlight the importance of the endothelium and the in vivo tissue-relevant dynamic microenvironment in the Colon Intestine-Chip in the establishment of a tight monolayer of differentiated, polarized, organoid-derived intestinal epithelial cells. We confirmed the effect of interferon-γ on the colonic barrier and identified reorganization of apical junctional complexes, and induction of apoptosis in the intestinal epithelial cells as mediating mechanisms. We show that in the human Colon Intestine-Chip exposure to interleukin 22 induces disruption of the barrier, unlike its described protective role in experimental colitis in mice.ConclusionsWe developed a human Colon Intestine-Chip platform and showed its value in the characterization of the mechanism of action of interleukin 22 in the human epithelial barrier. This system can be used to elucidate, in a time- and challenge-dependent manner, the mechanism driving the development of leaky gut in human beings and to identify associated biomarkers.

Iohexol-based measurement of intestinal permeability in birds

Background: Iohexol has been successfully used as a marker to assess intestinal permeability in humans and various other mammals. The objective of this study was to evaluate the use of oral iohexol as an intestinal permeability marker in four anatomically and nutritionally diverse bird species. Methods: Three dosages (1 ml/kg, 2 ml/kg, 4 ml/kg) of iohexol (755 mg/ml) were administered orally to each six clinically healthy pigeons and chickens at two-week intervals. Iohexol plasma concentration was determined 45, 90 and 180 minutes after administration. A comparative study was performed by administering iohexol twice to each six clinically healthy cockatiels and falcons, and determining iohexol plasma concentration at 45 or 90 minutes after administration. Results: The recommended iohexol dosage for permeability testing in birds was determined to be 1 ml/kg. Median plasma iohexol concentrations were 27.77 µg/ml in pigeons, 12.97 µg/ml in chickens, 14.24 µg/ml in cockatiels, and 47.81 µg/ml in falcons, 45 minutes after this dosage was administered. At 90 minutes after administration, median plasma iohexol concentrations were 40.68 µg/ml in pigeons, 21.59 µg/ml in chickens, 32.03 µg/ml in cockatiels, and 55.96 µg/ml in falcons. Conclusions and clinical relevance: Oral iohexol was a safe and feasible marker for intestinal permeability assessment in birds. Further investigations are warranted to establish species-specific reference intervals in larger numbers of healthy birds, and to examine the use of iohexol as a permeability marker in birds with disorders associated with altered intestinal permeability.

Regional Intestinal Drug Permeability and Effects of Permeation Enhancers in Rat.

Sufficient colonic absorption is necessary for all systemically acting drugs in dosage forms that release the drug in the large intestine. Preclinically, colonic absorption is often investigated using the rat single-pass intestinal perfusion model. This model can determine intestinal permeability based on luminal drug disappearance, as well as the effect of permeation enhancers on drug permeability. However, it is uncertain how accurate the rat single-pass intestinal perfusion model predicts regional intestinal permeability and absorption in human. There is also a shortage of systematic in vivo investigations of the direct effect of permeation enhancers in the small and large intestine. In this rat single-pass intestinal perfusion study, the jejunal and colonic permeability of two low permeability drugs (atenolol and enalaprilat) and two high-permeability ones (ketoprofen and metoprolol) was determined based on plasma appearance. These values were compared to already available corresponding human data from a study conducted in our lab. The colonic effect of four permeation enhancers—sodium dodecyl sulfate, chitosan, ethylenediaminetetraacetic acid (EDTA), and caprate—on drug permeability and transport of chromium EDTA (an established clinical marker for intestinal barrier integrity) was determined. There was no difference in jejunal and colonic permeability determined from plasma appearance data of any of the four model drugs. This questions the validity of the rat single-pass intestinal perfusion model for predicting human regional intestinal permeability. It was also shown that the effect of permeation enhancers on drug permeability in the colon was similar to previously reported data from the rat jejunum, whereas the transport of chromium EDTA was significantly higher (p < 0.05) in the colon than in jejunum. Therefore, the use of permeation enhancers for increasing colonic drug permeability has greater risks than potential medical rewards, as indicated by the higher permeation of chromium EDTA compared to the drugs.

Standardizing Method and Development of Normal Values to Measure Human Small Intestinal and Colonic Permeability

Standardizing Method and Development of Normal Values to Measure Human Small Intestinal and Colonic Permeability

QSPR model for Caco-2 cell permeability prediction using a combination of HQPSO and dual-RBF neural network.

The Caco-2 cell model is widely used to evaluate the in vitro human intestinal permeability of drugs due to its morphological and functional similarity to human enterocytes. Although it is safe and relatively economic, it is time-consuming. A rapid and accurate quantitative structure-property relationship (QSPR) model of Caco-2 permeability is helpful to improve the efficiency of oral drug development. The aim of our study is to explore the predictive ability of the QSPR model, to study its permeation mechanism, and to develop a potential permeability prediction model, for Caco-2 cells. In our study, a relatively large data set was collected and the abnormal data were eliminated using the Monte Carlo regression and hybrid quantum particle swarm optimization (HQPSO) algorithm. Then, the remaining 1827 compounds were used to establish QSPR models. To generate multiple chemically diverse training and test sets, we used a combination of principal component analysis (PCA) and self-organizing mapping (SOM) neural networks to split the modeling data set characterized by PaDEL-descriptors. After preliminary selection of descriptors by the mean decrease impurity (MDI) method, the HQPSO algorithm was used to select the key descriptors. Six different methods, namely, multivariate linear regression (MLR), support vector machine regression (SVR), xgboost, radial basis function (RBF) neural networks, dual-SVR and dual-RBF were employed to develop QSPR models. The best dual-RBF model was obtained finally with R2 = 0.91, and Rcv52 = 0.77, for the training set, and RT2 = 0.77, for the test set. A series of validation methods were used to assess the robustness and predictive ability of the dual-RBF model under OECD principles. A new application domain (AD) definition method based on the descriptor importance-weighted and distance-based (IWD) method was proposed, and the outliers were analyzed carefully. Combined with the importance of the descriptors used in the dual-RBF model, we concluded that the “H E-state” and hydrogen bonds are important factors affecting the permeability of drugs passing through the Caco-2 cell. Compared with the reported studies, our method exhibits certain advantages in data size, transparency of modeling process and prediction accuracy to some extent, and is a promising tool for virtual screening in the early stage of drug development.

Effects of Acute and Chronic Exposure to Residual Level Erythromycin on Human Intestinal Epithelium Cell Permeability and Cytotoxicity.

Residual concentrations of erythromycin in food could result in gastrointestinal tract exposure that potentially poses a health-hazard to the consumer, affecting intestinal epithelial permeability, barrier function, microbiota composition, and antimicrobial resistance. We investigated the effects of erythromycin after acute (48 h single treatment with 0.03 μg/mL to 300 μg/mL) or chronic (repeated treatment with 0.3 µg/mL and 300 µg/mL erythromycin for five days) exposures on the permeability of human colonic epithelial cells, a model that mimics a susceptible intestinal surface devoid of commensal microbiota. Transepithelial electrical resistance (TER) measurements indicated that erythromycin above 0.3 µg/mL may compromise the epithelial barrier. Acute exposure increased cytotoxicity, while chronic exposure decreased the cytotoxicity. Quantitative PCR analysis revealed that only ICAM1 (intercellular adhesion molecule 1) was up-regulated during 0.3 μg/mL acute-exposure, while ICAM1, JAM3 (junctional adhesion molecule 3), and ITGA8 (integrin alpha 8), were over-expressed in the 300 μg/mL acute treatment group. However, during chronic exposure, no change in the mRNA expression was observed at 0.3 μg/mL, and only ICAM2 was significantly up-regulated after 300 μg/mL. ICAM1 and ICAM2 are known to be involved in the formation of extracellular matrices. These gene expression changes may be related to the immunoregulatory activity of erythromycin, or a compensatory mechanism of the epithelial cells to overcome the distress caused by erythromycin due to increased permeability.

Rat intestinal drug permeability: A status report and summary of repeated determinations

Intestinal permeability is a key biopharmaceutical variable in pharmaceutical research and development, and regulatory assessment. In situ rat models are often used to predict the corresponding human intestinal permeability data. The rat single-pass intestinal perfusion (SPIP) and intestinal closed loop (ICL) models are commonly applied. The primary objective of this study was to collect, summarize, and evaluate all the available intestinal permeability data for drugs that have been obtained using these two in-situ rat models. The permeability data were also investigated for variability between the experimental designs. The literature survey found 635 permeability determinations for 90 drugs. The studies were performed on the jejunum (n = 284), whole small intestine (n = 111), colon (n = 108), ileum (n = 101), and duodenum (n = 30). All the SPIP (n = 484) and ICL (n = 147) permeability values were summarized in an easily accessible database. There was wide variability in the intestinal permeability to each drug between studies, which was unrelated to the permeability class of the drug. There was no relationship between rat intestinal permeability and luminal pH, luminal drug concentration, rat strain, experimental method, or intestinal region. There was, however, a correlation between permeability values determined in the same laboratory. This report showed that the SPIP and ICL methods are important in situ models for understanding and predicting intestinal drug absorption. However, conclusions based on permeability values sourced from different laboratories may not be reliable. Because each permeability study is unique and because between- and even within-laboratory variability can be substantial, data from individual studies should preferably be interpreted separately.