Octreotide attenuates intestinal barrier damage by maintaining basal autophagy in Caco2 cells.

The intestinal mucosal barrier is of great importance for maintaining the stability of the internal environment, which is closely related to the occurrence and development of intestinal inflammation. Octreotide (OCT) has potential applicable clinical value for treating intestinal injury according to previous studies, but the underlying molecular mechanisms have remained elusive. This article is based on a cell model of inflammation induced by lipopolysaccharide (LPS), aiming to explore the effects of OCT in protecting intestinal mucosal barrier function. A Cell Counting Kit­8 assay was used to determine cell viability and evaluate the effectiveness of OCT. Gene silencing technology was used to reveal the mediated effect of somatostatin receptor 2 (SSTR2). The changes in intestinal permeability were detected through trans­epithelial electrical resistance and fluorescein isothiocyanate­dextran 4 experiments, and the alterations in tight junction proteins were detected using immunoblotting and reverse transcription fluorescence­quantitative PCR technology. Autophagosomes were observed by electron microscopy and the dynamic changes of the autophagy process were characterized by light chain (LC)3­II/LC3­I conversion and autophagic flow. The results indicated that SSTR2­dependent OCT can prevent the decrease in cell activity. After LPS treatment, the permeability of monolayer cells decreased and intercellular tight junctions were disrupted, resulting in a decrease in tight junction protein zona occludens 1 in cells. The level of autophagy­related protein LC3 was altered to varying degrees at different times. These abnormal changes gradually returned to normal levels after the combined application of LPS and SSTR2­dependent OCT, confirming the role of OCT in protecting intestinal barrier function. These experimental results suggest that OCT maintains basal autophagy and cell activity mediated by SSTR2 in intestinal epithelial cells, thereby preventing the intestinal barrier dysfunction in inflammation injury.

Delivery of miR-29a improves the permeability of cisplatin by downregulating collagen I expression.

In the clinical setting, chemotherapy is the most widely used antitumor treatment, however, chemotherapy resistance significantly limits its efficacy. Reduced drug influx is a key mechanism of chemoresistance, and inhibition of the complexity of the tumor microenvironment (TME) may improve chemotherapy drug influx and therapeutic efficiency. In the current study, we identified that the major extracellular matrix protein collagen I is more highly expressed in lung cancer tissues than adjacent tissues in patients with lung cancer. Furthermore, Kaplan-Meier analysis suggested that COL1A1 expression was negatively correlated with the survival time of patients with lung cancer. Our previous study demonstrated that miR-29a inhibited collagen I expression in lung fibroblasts. Here, we investigated the effect of miR-29a on collagen I expression and the cellular behavior of lung cancer cells. Our results suggest that transfection with miR-29a could prevent Lewis lung carcinoma (LLC) migration by downregulating collagen I expression, but did not affect the proliferation, apoptosis, and cell cycle of LLC cells. In a 3D tumoroid model, we demonstrated that miR-29a transfection significantly increased cisplatin (CDDP) permeation and CDDP-induced cell death. Furthermore, neutral lipid emulsion-based miR-29a delivery improved the therapeutic effect of cisplatin in an LLC spontaneous tumor model in vivo. In summary, this study shows that targeting collagen I expression in the TME contributes to chemotherapy drug influx and improves therapeutic efficacy in lung cancer.

Non-animal models for blood-brain barrier permeability evaluation of drug-like compounds.

Diseases related to the central nervous system (CNS) are major health concerns and have serious social and economic impacts. Developing new drugs for CNS-related disorders presents a major challenge as it actively involves delivering drugs into the CNS. Therefore, it is imperative to develop in silico methodologies to reliably identify potential lead compounds that can penetrate the blood-brain barrier (BBB) and help to thoroughly understand the role of different physicochemical properties fundamental to the BBB permeation of molecules. In this study, we have analysed the chemical space of the CNS drugs and compared it to the non-CNS-approved drugs. Additionally, we have collected a feature selection dataset from Muehlbacher et al. (J Comput Aided Mol Des 25(12):1095-1106, 2011. 10.1007/s10822-011-9478-1) and an in-house dataset. This information was utilised to design a molecular fingerprint that was used to train machine learning (ML) models. The best-performing models reported in this study achieved accuracies of 0.997 and 0.98, sensitivities of 1.0 and 0.992, specificities of 0.971 and 0.962, MCCs of 0.984 and 0.958, and ROC-AUCs of 0.997 and 0.999 on an imbalanced and a balanced dataset, respectively. They demonstrated overall good accuracies and sensitivities in the blind validation dataset. The reported models can be applied for fast and early screening drug-like molecules with BBB potential. Furthermore, the bbbPythoN package can be used by the research community to both produce the BBB-specific molecular fingerprints and employ the models mentioned earlier for BBB-permeability prediction.

Neurotensin modulates ovarian vascular permeability via adherens junctions.

Neurotensin (NTS) is a 13-amino acid peptide which is highly expressed in the mammalian ovary in response to the luteinizing hormone surge. Antibody neutralization of NTS in the ovulatory follicle of the cynomolgus macaque impairs ovulation and induces follicular vascular dysregulation, with excessive pooling of red blood cells in the follicle antrum. We hypothesize that NTS is an essential intrafollicular regulator of vascular permeability. In the present study, follicle injection of the NTS receptor antagonist SR142948 also resulted in vascular dysregulation. To measure vascular permeability changes in vitro, primary macaque ovarian microvascular endothelial cells (mOMECs) were enriched from follicle aspirates and studied in vitro. When treated with NTS, permeability of mOMECs decreased. RNA sequencing (RNA-Seq) of mOMECs revealed high mRNA expression of the permeability-regulating adherens junction proteins N-cadherin (CDH2) and K-cadherin (CDH6). Immunofluorescent detection of CDH2 and CDH6 confirmed expression and localized these cadherins to the cell-cell boundaries, consistent with function as components of adherens junctions. mOMECs did not express detectable levels of the typical vascular endothelial cadherin, VE-cadherin (CDH5) as determined by RNA-Seq, qPCR, western blot, and immunofluorescence. Knockdown of CDH2 or CDH6 via siRNA abrogated the NTS effect on mOMEC permeability. Collectively, these data suggest that NTS plays an ovulation-critical role in vascular permeability maintenance, and that CDH2 and CDH6 are involved in the permeability modulating effect of NTS on the ovarian microvasculature. NTS can be added to a growing number of angiogenic regulators which are critical for successful ovulation.

22q11.2 Deletion-Associated Blood-Brain Barrier Permeability Potentiates Systemic Capillary Leak Syndrome Neurologic Features.

We present a case study of a young male with a history of 22q11.2 deletion syndrome (22qDS), diagnosed with systemic capillary leak syndrome (SCLS) who presented with acute onset of diffuse anasarca and sub-comatose obtundation. We hypothesized that his co-presentation of neurological sequelae might be due to blood-brain barrier (BBB) susceptibility conferred by the 22q11.2 deletion, a phenotype that we have previously identified in 22qDS. Using pre- and post-intravenous immunoglobulins (IVIG) patient serum, we studied circulating biomarkers of inflammation and assessed the potential susceptibility of the 22qDS BBB. We employed in vitro cultures of differentiated BBB-like endothelial cells derived from a 22qDS patient and a healthy control. We found evidence of peripheral inflammation and increased serum lipopolysaccharide (LPS) alongside endothelial cells in circulation. We report that the patient's serum significantly impairs barrier function of the 22qDS BBB compared to control. Only two other cases of pediatric SCLS with neurologic symptoms have been reported, and genetic risk factors have been suggested in both instances. As the third case to be reported, our findings are consistent with the hypothesis that genetic susceptibility of the BBB conferred by genes such as claudin-5 deleted in the 22q11.2 region promoted neurologic involvement during SCLS in this patient.

SARS-CoV-2 presence in recreational seawater and evaluation of intestine permeability: experimental evidence of low impact on public health.

Introduction: Coastal seawater pollution poses a public health risk due to the potential ingestion of contaminated water during recreational activities. Wastewater-based epidemiology has revealed the abundant presence of SARS-CoV-2 in seawater emitted from wastewater outlets. The objective of this research was to investigate the impact of seawater on SARS-CoV-2 infectivity to assess the safety of recreational activities in seawater. Methods: Wild SARS-CoV-2 was collected from oral swabs of COVID-19 affected patients and incubated for up to 90 min using the following solutions: (a) standard physiological solution (control), (b) reconstructed seawater (3.5% NaCl), and (c) authentic seawater (3.8%). Samples were then exposed to two different host systems: (a) Vero E6 cells expressing the ACE2 SARS-CoV-2 receptor and (b) 3D multi-tissue organoids reconstructing the human intestine. The presence of intracellular virus inside the host systems was determined using plaque assay, quantitative real-time PCR (qPCR), and transmission electron microscopy. Results: Ultrastructural examination of Vero E6 cells revealed the presence of virus particles at the cell surface and in replicative compartments inside cells treated with seawater and/or reconstituted water only for samples incubated up to 2 min. After a 90-min incubation, the presence of the virus and its infectivity in Vero E6 cells was reduced by 90%. Ultrastructural analysis performed in 3D epi-intestinal tissue did not reveal intact viral particles or infection signs, despite the presence of viral nucleic acid detected by qPCR. Indeed, viral genes (Orf1ab and N) were found in the intestinal luminal epithelium but not in the enteric capillaries. These findings suggest that the intestinal tissue is not a preferential entry site for SARS-CoV-2 in the human body. Additionally, the presence of hypertonic saline solution did not increase the susceptibility of the intestinal epithelium to virus penetration; rather, it neutralized its infectivity. Conclusion: Our results indicate that engaging in recreational activities in a seawater environment does not pose a significant risk for COVID-19 infection, despite the possible presence of viral nucleic acid deriving from degraded and fragmented viruses.

Molecular mechanism of action of imidazolium carbosilane dendrimers on the outer bacterial membrane - From membrane damage to permeability to antimicrobial endolysin.

The outer bacterial membrane of drug-resistant bacteria is a significant barrier to many antimicrobials. Therefore, the development of new antibacterials primarily focuses on damaging the outer bacterial membrane of Gram-negative bacteria. Among many membrane-disrupting substances, the most promising are cationic dendritic systems. However, the mode of action may vary among different strains due to variations in the lipid compositions of the membrane. Here, we investigated the interaction of two types of cationic imidazolium carbosilane dendrimers: one with a single cationic group (methyl imidazolium) and the other with the same cationic group but attached to a functional group (a pendant pyridyl moiety), capable of establishing interactions with membranes through H-bonding or ion-dipole electrostatic interactions. We used different models of the outer membrane of Gram-negative bacteria - Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii. Additionally, we assessed the combined effect of the dendrimers and the antibacterial endolysin on P. aeruginosa. Our results show that the mechanism of action depends on the type of dendrimer and the lipid composition of the membrane. We also demonstrate that the alteration of membrane fluidity and permeability to endolysin by the methyl imidazolium and pyridyl imidazolium dendrimers may play a more significant role in antimicrobial activity compared to membrane damage caused by positively charged dendrimers.

FXR1 stabilizes SNORD63 to regulate blood-tumor barrier permeability through SNORD63 mediated 2'-O-methylation of POU6F1.

How selectively increase blood-tumor barrier (BTB) permeability is crucial to enhance the delivery of chemotherapeutic agents to brain tumor tissues. In this study, we established in vitro models of the blood-brain barrier (BBB) and BTB using endothelial cells (ECs) co-cultured with human astrocytes (AECs) and glioma cells (GECs), respectively. The findings revealed high expressions of the RNA-binding protein FXR1 and SNORD63 in GECs, where FXR1 was found to bind and stabilize SNORD63. Knockdown of FXR1 resulted in decreased expression of tight-junction-related proteins and increased BTB permeability by down-regulating SNORD63. SNORD63 played a role in mediating the 2'-O-methylation modification of POU6F1 mRNA, leading to the downregulation of POU6F1 protein expression. POU6F1 showed low expression in GECs and acted as a transcription factor to regulate BTB permeability by binding to the promoter regions of ZO-1, occludin, and claudin-5 mRNAs and negatively regulating their expressions. Finally, the targeted regulation of FXR1, SNORD63, and POU6F1 expressions, individually or in combination, effectively enhanced doxorubicin passage through the BTB and induced apoptosis in glioma cells. This study aims to elucidate the underlying mechanism of the FXR1/SNORD63/POU6F1 axis in regulating BTB permeability, offering a novel strategy to improve the efficacy of glioma chemotherapy.

Enhanced carbohydrate-based plastic performance by incorporating cerium-based metal-organic framework for food packaging application.

The development of biodegradable active packaging films with hydrophobic characteristics is vital for extending the shelf life of food and reducing the reliance on petroleum-based plastics. In this study, novel hydrophobic cerium-based metal-organic framework (Ce-MOF) nanoparticles were successfully synthesized. The Ce-MOF nanoparticles were then incorporated into the cassava starch matrix at varying concentrations (0.5 %, 1.5 %, 3 %, and 4 % w/w of total solid) to fabricate cassava-based active packaging films via the solution casting technique. The influence of Ce-MOF on the morphology, thermal attributes, and physicochemical properties of the cassava film was subsequently determined through further analyses. Biomedical analysis including antioxidant activity and the cellular morphology evaluation in the presence of the films was also conducted. The results demonstrated that the consistent dispersion of Ce-MOF nanofillers within the cassava matrix led to a significant enhancement in the film's crystallinity, thermal stability, antioxidant activity, biocompatibility, and hydrophobicity. The introduction of Ce-MOF also contributed to the film's reduced water solubility. Considering these outcomes, the developed cassava/Ce-MOF films undoubtedly have significant potential for active food packaging applications.

Saponaria officinalis saponins as a factor increasing permeability of Candida yeasts' biomembrane.

Saponins are a large group of compounds, produced mostly by plants as a side product of their metabolic activity. These compounds have attracted much attention over the years mostly because of their surface activity and antibacterial, anti-inflammatory and antifungal properties. On the other hand, most of the hitherto research has concerned the action of saponins against microbial cells as a whole. Therefore, knowing the possible interaction of saponins with biomembrane, we decided to check in-vitro the influence of saponin-rich extract of Saponaria officinalis on spheroplasts of two Candida sp. The obtained results show that 10 mg L- 1 of extract increased the permeability of spheroplasts up to 21.76% relative to that of the control sample. Moreover, the evaluation of surface potential has revealed a decrease by almost 10 mV relative to that of the untreated samples. Such results suggest its direct correlation to integration of saponins into the biomembrane structure. The obtained results have proved the antifungal potential of saponins and their ability of permeabilization of cells. This proves the high potential of saponins use as additives to antifungal pharmaceutics, which is expected to lead to improvement of their action or reduction of required dosage.

Bactericidal/permeability-increasing protein instructs dendritic cells to elicit Th22 cell response.

Neutrophil-derived bactericidal/permeability-increasing protein (BPI) is known for its bactericidal activity against gram-negative bacteria and neutralization of lipopolysaccharide. Here, we define BPI as a potent activator of murine dendritic cells (DCs). As shown in GM-CSF-cultured, bone-marrow-derived cells (BMDCs), BPI induces a distinct stimulation profile including IL-2, IL-6, and tumor necrosis factor expression. Conventional DCs also respond to BPI, while M-CSF-cultivated or peritoneal lavage macrophages do not. Subsequent to BPI stimulation of BMDCs, CD4+ T cells predominantly secrete IL-22 and, when naive, preferentially differentiate into T helper 22 (Th22) cells. Congruent with the tissue-protective properties of IL-22 and along with impaired IL-22 induction, disease severity is significantly increased during dextran sodium sulfate-induced colitis in BPI-deficient mice. Importantly, physiological diversification of intestinal microbiota fosters BPI-dependent IL-22 induction in CD4+ T cells derived from mesenteric lymph nodes. In conclusion, BPI is a potent activator of DCs and consecutive Th22 cell differentiation with substantial relevance in intestinal homeostasis.

ADAMTS5 Promotes Permeability of the Blood-Brain Barrier during Treponema pallidum Subspecies pallidum Invading the Central Nervous System.

The pathogenesis of neurosyphilis remains unclear. A previous study found a noteworthy up-regulation of a disintegrin and metalloproteinase with thrombospondin type 1 motif 5 (ADAMTS5) gene in human brain microvascular endothelial cells cocultured with Treponema pallidum subspecies pallidum (Tp). To investigate the ADAMTS5 role in Tp invading the central nervous system (CNS), we conducted relevant experiments. Our study revealed that Tp caused an increase in human cortical microvascular endothelial cell/D3 (hCMEC/D3) barrier permeability and significantly enhanced ADAMTS5 expression. The heightened permeability of the hCMEC/D3 barrier was effectively mitigated by inhibiting ADAMTS5. During this process, Tp promoted interleukin-1ß production, which, in turn, facilitated ADAMTS5 expression. Furthermore, Tp significantly reduced the glycocalyx on the surface of hCMEC/D3 cells, which was also ameliorated by inhibiting ADAMTS5. Additionally, ADAMTS5 and endothelial glycocalyx components notably increased in the cerebrospinal fluid of HIV-negative neurosyphilis patients. This research provided the first demonstration of the ADAMTS5 role in Tp invading the CNS and offered new insight into neurosyphilis pathogenesis.

Early Increase in Blood-Brain Barrier Permeability in a Murine Model Exposed to Fifteen Days of Intermittent Hypoxia.

Obstructive sleep apnea (OSA) is characterized by intermittent repeated episodes of hypoxia-reoxygenation. OSA is associated with cerebrovascular consequences. An enhanced blood-brain barrier (BBB) permeability has been proposed as a marker of those disorders. We studied in mice the effects of 1 day and 15 days intermittent hypoxia (IH) exposure on BBB function. We focused on the dorsal part of the hippocampus and attempted to identify the molecular mechanisms by combining in vivo BBB permeability (Evans blue tests) and mRNA expression of several junction proteins (zona occludens (ZO-1,2,3), VE-cadherin, claudins (1,5,12), cingulin) and of aquaporins (1,4,9) on hippocampal brain tissues. After 15 days of IH exposure we observed an increase in BBB permeability, associated with increased mRNA expressions of claudins 1 and 12, aquaporins 1 and 9. IH seemed to increase early for claudin-1 mRNA expression as it doubled with 1 day of exposure and returned near to its base level after 15 days. Claudin-1 overexpression may represent an immediate response to IH exposure. Then, after 15 days of exposure, an increase in functional BBB permeability was associated with enhanced expression of aquaporin. These BBB alterations are possibly associated with a vasogenic oedema that may affect brain functions and accelerate neurodegenerative processes.

In vitro mucin degradation and paracellular permeability by fecal water from Crohn's disease patients.

Aim: This study aimed to examine the impact of fecal water (FW) of active and remissive Crohn's disease (CD) patients on mucin degradation and epithelial barrier function. Methods: FW and bacterial membrane vesicles (MVs) were isolated from fresh fecal samples of six healthy controls (HCs) and 12 CD patients. Bacterial composition was determined by 16S rRNA gene amplicon sequencing. Results: In vitro FW-induced mucin degradation was higher in CD samples versus HC (p < 0.01), but not associated with specific bacterial genera. FW of three remissive samples decreased transepithelial electrical resistance in Caco-2 cells by 78-87% (p < 0.001). MVs did not induce barrier alterations. Conclusion: The higher mucin-degradation capacity of CD-derived FW might suggest contributions of microbial products to CD pathophysiology.

Border Control: The Role of the Microbiome in Regulating Epithelial Barrier Function.

The gut mucosal epithelium is one of the largest organs in the body and plays a critical role in regulating the crosstalk between the resident microbiome and the host. To this effect, the tight control of what is permitted through this barrier is of high importance. There should be restricted passage of harmful microorganisms and antigens while at the same time allowing the absorption of nutrients and water. An increased gut permeability, or "leaky gut", has been associated with a variety of diseases ranging from infections, metabolic diseases, and inflammatory and autoimmune diseases to neurological conditions. Several factors can affect gut permeability, including cytokines, dietary components, and the gut microbiome. Here, we discuss how the gut microbiome impacts the permeability of the gut epithelial barrier and how this can be harnessed for therapeutic purposes.

Electroacupuncture stimulation enhances the permeability of the blood-brain barrier: A systematic review and meta-analysis of preclinical evidence and possible mechanisms.

An important cellular barrier to maintain the stability of the brain's internal and external environment is the blood-brain barrier (BBB). It also prevents harmful substances from entering brain tissue through blood circulation while providing protection for the central nervous system. It should be noted, however, that the intact BBB can be a barrier to the transport of most drugs into the brain via the conventional route of administration, which can prevent them from reaching effective concentrations for the treatment of disorders affecting the central nervous system. Electroacupuncture stimulation has been shown to be effective at opening the BBB in a series of experimental studies. This study systematically analyzes the possibility and mechanism by which electroacupuncture opens the BBB. In PubMed, Web of Science, VIP Database, Wanfang Database, and the Chinese National Knowledge Infrastructure, papers have been published for nearly 22 years aimed at opening the BBB and its associated structures. A comparison of EB content between electroacupuncture and control was selected as the primary outcome. There were also results on vascular endothelial growth factor (VEGF), nerve growth factor (NGF), P-Glycoprotein (P-gp), Matrix Metalloproteinase 9 (MMP-9), and glial fibrillary acidic protein (GFAP). We utilized Review Manager software analysis to analyze correlations between studies with a view to exploring the mechanisms of similarity. Evans Blue infiltration forest plot: pooled effect size of 2.04, 95% CI: 1.21 to 2.87, P < 0.01. These results indicate that electroacupuncture significantly increases EB penetration across the BBB. Most studies have reported that GFAP, MMP-9, and VEGF were upregulated after treatment. P-gp expression decreased as well. Electroacupuncture can open the BBB, and the sparse-dense wave is currently the most effective electroacupuncture frequency for opening the BBB. VEGF plays an important role in opening the BBB. It is also important to regulate the expression of MMP-9 and GFAP and inhibit the expression of P-gp.

Physical characterization and bioavailability assessment of 5-fluorouracil-based nanostructured lipid carrier (NLC): In vitro drug release, Hemolysis, and permeability modulation.

5-Fluorouracil (5-FU) is an anticancer agent belonging to BCS Class III that exhibits poor release characteristics and low retention in the biological system. The main objective of this investigation was to develop a drug delivery system, i.e., Nanostructure Lipid Carriers (NLCs) loaded with 5-FU to prolong its biological retention through 5-FU-loaded NLCs (5-FUNLC) were designed to manipulate physicochemical characteristics and assessment of in vitro and in vivo performance. The developed NLCs underwent comprehensive characterization, including assessments for particle size, zeta potential, morphological evaluation, and FT-IR spectroscopy. Additionally, specific evaluations were conducted for 5-FUNLCs, encompassing analyses for encapsulation efficiency of the drug, release characteristics in PBS at pH 6.8, and stability study. The lipophilic character of 5-FUNLC was confirmed through the measurement of the partition coefficient (log P). 5-FUNLCs were observed as spherical-shaped particles with a mean size of 300 ± 25 nm. The encapsulation efficiency was determined to be 89%, indicating effective drug loading within the NLCs. Furthermore, these NLCs exhibited a sustained release nature lasting up to 3-4 h, indicating their potential for controlled drug release over time. Lipid components were biocompatible with the 5-FU to determine thermal transition temperature and show good stability for 30 days. Additionally, an in vitro hemolysis study that confirmed the system did not cause any destruction to the RBCs during intravenous administration. The drug's gut permeability was assessed utilizing the optimized 5-FUNLC (F2) in comparison to 5-FU through the intestine or gut sac model (in the apical to basolateral direction, A → B). The permeability coefficient was measured as 4.91 × 10-5 cm/h with a significant difference. Additionally, the antioxidant potential of the NLCs was demonstrated through the DPPH method. The NLCs' performance was further assessed through in vivo pharmacokinetic studies on Wistar Rats, resulting in a 1.5-fold enhancement in their activity compared to free 5-FU. These NLCs offer improved drug solubility and sustained release, which collectively contribute to enhanced therapeutic outcomes and modulate bioavailability. The study concludes by highlighting the potential of 5-FUNLC as an innovative and efficient drug delivery system. The findings suggest that further preclinical investigations are warranted, indicating a promising avenue for the development of more effective and well-tolerated treatments for cancer.

Mitigation effect of hesperidin on X-ray radiation-induced intestinal barrier dysfunction in Caco-2 cell monolayers.

The tight junctions (TJs) and barrier function of the intestinal epithelium are highly sensitive to radiation. However, polyphenols can be used to reverse the effects of radiation. Here, we investigated the effects of hesperidin (hesperetin-7-rhamnoglucoside) on X-ray-induced intestinal barrier dysfunction in human epithelial Caco-2 monolayers. To examine whether hesperidin mitigated the effects of X-ray exposure (2 Gy), cell survival was evaluated and intestinal barrier function was assessed by measuring the transepithelial flux, apparent permeability coefficient (Papp), and barrier integrity. Hesperidin improved the survival of Caco-2 cell monolayers and attenuated X-ray exposure-induced intestinal barrier dysfunction. For fluorescein transport experiments, transepithelial flux and Papp of fluorescein in control group were significantly elevated by X-ray, but were restored to near control by 10 µM hesperidin pretreatment. Further, X-ray exposure decreased the barrier integrity and TJ interruption by reducing TJ-related proteins occludin and claudin-4, whereas cell monolayers pretreated with hesperidin before X-ray exposure were reinstated to control level. It was concluded that hesperidin treatment before X-ray exposure alleviated X-ray-induced intestinal barrier dysfunction through regulation of TJ-related proteins. These results indicate that hesperidin prevents and mitigates X-ray-induced intestinal barrier dysfunction.

Disruption of intestinal epithelial permeability in the Co-culture system of Caco-2/HT29-MTX cells exposed individually or simultaneously to acrylamide and ochratoxin A.

Mycotoxins and thermal processing hazards are common contaminants in various foods and cause severe problems in terms of food safety and health. Combined use of acrylamide (AA) and ochratoxin A (OTA) would result in more significant intestinal toxicity than either toxin alone, but the underlying mechanisms behind this poor outcome remain unclear. Herein, we established the co-culture system of Caco-2/HT29-MTX cells for simulating a real intestinal environment that is more sensitive to AA and OTA, and showed that the combination of AA and OTA could up-regulate permeability of the intestine via increasing LY permeabilization, and decreasing TEER, then induce oxidative stress imbalance (GSH, SOD, MDA, and ROS) and inflammatory system disorder (TNF-α, IL-1ß, IL-10, and IL-6), thereby leading a rapid decline in cell viability. Western blot, PAS- and AB-staining revealed that AA and OTA showed a synergistic effect on the intestine mainly through the disruption of tight junctions (TJs) and a mucus layer. Furthermore, based on correlation analysis, oxidative stress was more relevant to the mucus layer and TJs. Therefore, our findings provide a better evaluation model and a potential mechanism for further determining or preventing the combined toxicity caused by AA and OTA.

Rectifying artificial nanochannels with multiple interconvertible permeability states.

Transmembrane channels play a vital role in regulating the permeation process, and have inspired recent development of biomimetic channels. Herein, we report a class of artificial biomimetic nanochannels based on DNAzyme-functionalized glass nanopipettes to realize delicate control of channel permeability, whereby the surface wettability and charge can be tuned by metal ions and DNAzyme-substrates, allowing reversible conversion between different permeability states. We demonstrate that the nanochannels can be reversibly switched between four different permeability states showing distinct permeability to various functional molecules. By embedding the artificial nanochannels into the plasma membrane of single living cells, we achieve selective transport of dye molecules across the cell membrane. Finally, we report on the advanced functions including gene silencing of miR-21 in single cancer cells and selective transport of Ca2+ into single PC-12 cells. In this work, we provide a versatile tool for the design of rectifying artificial nanochannels with on-demand functions.