Search Results (434)

Irritable bowel syndrome (IBS) is a common disorder of gut–brain interaction (DGBI) of multifactorial genesis. Studies consistently show a disrupted intestinal barrier with increased permeability in IBS patients, regardless of subtype. This allows facultative pathogenic bacteria to translocate into underlying body tissue and to initiate or exacerbate IBS symptoms. Protecting the intestinal barrier is therefore a primary therapeutic target. Bifidobacterium bifidum MIMBb75 has proven its efficacy in IBS both in its viable and heat-inactivated forms. Its efficacy is thought to be mediated by the physical adhesion of B. bifidum MIMBb75 to intestinal epithelial cells, thereby protecting the intestinal barrier. In the present study, we show—using a Caco-2 model—that this strain-specific adhesion is facilitated by the high cell surface hydrophobicity of B. bifidum MIMBb75, which is retained following heat inactivation. In line with these adhesive properties, both viable and heat-inactivated B. bifidum MIMBb75 protect the epithelial barrier, as indicated by an increased transepithelial electrical resistance in Caco-2 monolayers. Together, these findings strongly support a physical mode of action in which both viable and heat-inactivated B. bifidum MIMBb75 adhere to the epithelial surface and act, figuratively, as a protective plaster on the epithelial barrier. Full article

Marine-derived collagen peptides exhibit potent intestinal barrier protection; however, their gastrointestinal fate and molecular targets remain unclear, limiting their practical applications. This study investigated the digestive stability and transepithelial transport of GPSGPQGSR, a mucoprotective peptide from Alaska pollock (Gadus chalcogrammus) skin, using simulated gastrointestinal digestion, a Caco-2 cell transport model, and an UPLC-QTOF-MS/MS. The results showed that GPSGPQGSR was a digestion-resistant peptide that reached the intestinal epithelium intact. Although brush border membrane enzymes partially hydrolysed the peptide, 42.16% of intact GPSGPQGSR remained in the luminal compartment after 2 h of incubation. No intact peptide was detected in the basolateral compartment. Molecular docking and 100 ns molecular dynamics simulations identified TLR2 (−14.936 kcal/mol) and PAR2 (−10.154 kcal/mol) as high-affinity extracellular targets of GPSGPQGSR, with stable peptide–receptor interactions and extensive hydrogen bonding networks between the peptide and each receptor (RMSD of 1.8 Å and 2.2 Å, respectively). Pharmacological blockade of TLR2 or PAR2 abolished the protective effects of GPSGPQGSR. These findings demonstrate that GPSGPQGSR acts as a digestion-resistant extracellular signalling peptide that reaches the intestinal epithelium intact and protects barrier function through apical TLR2 and PAR2, providing a mechanistic basis for the rational development of marine collagen peptides for improving intestinal health. Full article

Improvement of bowel function is accompanied by increased luminal flow and altered epithelial mechanical forces, yet the underlying epithelial mechanisms remain unclear. We investigated whether enhanced luminal stimulation is associated with epithelial mechanotransduction and junctional remodeling during changes in colonic motility. Sennoside was orally administered at 4.8 mg/kg body weight to 5-week-old male BALB/cAJcl mice for 21 days to model increased luminal stimulation. Stool characteristics, fecal water content, Bristol Stool Form Scale scores, and segmental colonic motility were assessed. Expression of Muc2, inflammatory cytokines, Trpv4, and E-cadherin was quantified across colonic regions. In CT26 monolayers, mechanical stress was applied to evaluate transient receptor potential channel induction, E-cadherin redistribution, and transepithelial electrical resistance, and the effect of Trpv4 knockdown. Sennoside softened stools, increased fecal water content (+18%) and Bristol scores (+57%), and enhanced distal colonic motility (+117%) without altering inflammatory cytokines. Trpv4 was selectively upregulated in the distal colon (3.3-fold). E-cadherin expression increased (2.5-fold) with junctional redistribution, whereas Muc2 decreased (−44%). In vitro, mechanical stress upregulated Trpv4 (2.5-fold), increased barrier resistance (+48%), and promoted E-cadherin assembly; these effects were augmented by sennoside and attenuated by Trpv4 silencing. These findings suggest that epithelial responses involving TRPV4-associated mechanotransduction and junctional remodeling are associated with altered barrier-related properties and distal colonic functional changes, providing insight into an epithelial component of stimulant laxative action. Full article

Air–liquid interface (ALI) cultures recapitulate key features of the airway epithelium by driving basal cell differentiation into ciliated, club, and goblet cells and by generating a functional mucus barrier, thereby representing a highly relevant model of the human respiratory tract. Using a reduced factorial Design of Experiments (DoE) methodology, we simultaneously investigated the effects of seven variables on human coronavirus OC43 (HCoV-OC43) replication in air–liquid interface (ALI)-cultured primary human bronchial epithelial cells (pHBECs) to identify robust conditions that support infection and viral replication. Epithelial differentiation was monitored by measuring transepithelial electrical resistance and determining expression levels of marker genes for basal, goblet, club, and ciliated cells using reverse transcription quantitative PCR (RT-qPCR). HCoV-OC43 replication was monitored by quantifying genomic and subgenomic RNA by RT-qPCR. Viral RNA peaked three days post-infection in cell lysates and four days post-infection in apical washes. Initiation of ALI conditions induced epithelial differentiation, which was complete after 21 days and emerged as the strongest determinant of viral replication. Differentiated pHBEC cultures showed significantly reduced viral RNA compared with undifferentiated cultures, particularly following apical infection. In contrast, basal infection resulted in lower viral RNA levels in undifferentiated cultures than apical infection but was less dependent on epithelial differentiation. However, productive infection following basal exposure was less consistent and more strongly dependent on viral inoculum size. We further demonstrate that repeated mucus washes prior to infection increased HCoV-OC43 replication in mature cultures. In summary, our findings show that epithelial differentiation negatively affects HCoV-OC43 replication and we identify conditions that maximize viral replication in fully differentiated pHBEC cultures. Full article

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) represents a globally prevalent hepatic disorder, characterized by hepatic lipid accumulation and extrahepatic complications, notably intestinal barrier injury, which further exacerbates MASLD progression. The “gut–liver axis” has been identified as a critical contributor to MASLD development, with insulin-like growth factor 1 (IGF-1) serving as a pivotal coupling factor of this axis. However, the specific role and molecular mechanism by which IGF-1 modulates intestinal barrier function in the context of MASLD remains unclear. Methods: This study analyzed the correlations between the GH/IGF-1 axis and intestinal barrier function in MASLD rats, and explored the effects of IGF-1 intervention both in vivo and in vitro. Results: Our results showed that MASLD rats exhibited intestinal barrier impairment, characterized by elevated serum Diamine oxidase (DAO) and D-Lactate (D-LAC) levels, villus damage, and downregulation of tight junction proteins and Mucin (MUC2). These changes were accompanied by suppression of the GH/IGF-1 axis. Correlation analysis uncovered a negative association between IGF-1 levels and markers of barrier dysfunction. IGF-1 intervention effectively repaired the intestinal barrier structure of MASLD rats and significantly upregulated the expressions of IGF-1R, PI3K, and AKT. In vitro, IGF-1 treatment improved transepithelial electrical resistance (TEER), enhanced barrier-related gene expression, promoted cell proliferation, and inhibited apoptosis. Conclusions: These findings suggested that GH/IGF-1 axis suppression, intestinal barrier dysfunction, and IGF-1R/PI3K/AKT signaling were interconnected within the gut–liver axis in MASLD. IGF-1 may contribute to barrier regulation through associated signaling changes, highlighting the GH/IGF-1 axis as a potential complementary target. Full article

Background and Objectives: Dysfunction of the airway epithelial barrier is increasingly recognized as an early pathogenic mechanism in allergic respiratory diseases. Although individual aeroallergens such as ragweed (RW) pollen and house dust mite (HDM) are known to impair epithelial integrity, the effects of combined exposure, more reflective of real-world conditions, remain insufficiently characterized. This study aimed to evaluate the impact of single versus combined allergen exposure on airway epithelial barrier function using a multimodal experimental approach. Materials and Methods: Differentiated normal human bronchial epithelial (NHBE) cells were exposed to RW (100 µg/mL), HDM (100 µg/mL), or a combined extract (RW + HDM; total 100 µg/mL). Barrier function under air–liquid interface conditions was assessed by transepithelial electrical resistance (TEER), while real-time cellular responses were evaluated using xCELLigence impedance monitoring. Structural alterations were examined by occludin-based immunofluorescence imaging, and transcriptional changes associated with epithelial stress and inflammation were analyzed by RT-qPCR. Results: Allergen exposure induced time- and concentration-dependent impairment of epithelial barrier function. Combined exposure resulted in the most pronounced and sustained reduction in TEER and impedance measurements. These functional changes were accompanied by disruption of tight junction organization and coordinated transcriptional modulation of genes involved in inflammatory and stress responses. Conclusions: Combined exposure to RW and HDM extracts induced more severe and persistent epithelial barrier dysfunction than individual allergens. These findings support the role of the airway epithelium as a central regulator of allergic airway disease and highlight barrier disruption as an early pathogenic event. The multimodal framework applied in this study provides an integrated platform for investigating epithelial responses to complex environmental exposures. Full article

For testing ocular irritation, 3D corneal models mimicking the corneal epithelium are considered reliable eye irritation tests and are detailed in regulatory guideline OECD Test Guideline (TG) 492. The aim of the present study was to develop and validate a Reconstructed human Cornea-like Epithelium (RhCE) in vitro irritation test method for ophthalmic medical devices according to OECD TG 492. Immortalized Human Primary Corneal Epithelium Cells (IM-HCEpiCs) were cultured on microporous inserts and exposed to an Air–Liquid Interface (ALI). Morphology was examined using standard (immuno-) histological techniques. Viability was quantified with MTT assay. Barrier integrity and function were monitored by trans-epithelial electrical resistance (TEER) and determination of IC₅₀ using MTT assay. Reproducibility was evaluated by calculating the inter-batch coefficient of variation (CV %) of the absorbance values of negative control-treated RhCE model replicates by MTT assay. Technical proficiency was verified using reference chemicals. Irritancy of ophthalmic medical devices was assessed. IM-HCEpiCs developed an epithelium-like barrier under the ALI. TEER increased after ALI introduction, and the obtained IC₅₀ value showed concordance with the guideline’s reference ranges. The developed RhCE test method demonstrated technical proficiency and correctly identified medical devices as non-irritants. A novel RhCE model was developed and validated according to OECD TG 492. Full article

The association between dietary fiber and phenolic compounds allows the latter to reach the colon, where most polysaccharides undergo fermentation. This bioprocessing weakens the matrix and promotes the release of the phenolic compounds, which then exert beneficial effects on intestinal function. Although this notion is widely accepted, supporting evidence remains scarce. In this study, we subjected grape pomace skin to in vitro digestion to obtain an indigestible fraction suitable for SHIME bioreactors. Throughout these stages, we observed a sequential increase in the release of phenolic compounds, with colonic fermentation playing an important role. Although we did not observe an increase in short-chain fatty acid (SCFA) production by the gut microbiota, we performed a repeated-challenge design on differentiated Caco-2 monolayers. With this approach, we found that the phenolic-rich ferment prevented the transepithelial electrical resistance (TEER) drop on the second challenge and modulated the transcriptomic profile assessed by RNA-seq. Our findings indicate that the Caco-2 cellular responses mentioned above were SCFA-independent and likely due to the differential impact of phenolic compound load after colonic fermentation of grape pomace skin. Full article

In vitro cell barrier models have been increasingly integrated into pharmaceutical and academic research pipelines to evaluate drug safety and drug delivery due to a shift towards New Approach Methodologies (NAMs) in research and regulatory safety assessment. Such models require reliable and interpretable functional readouts. Bioimpedance-based monitoring, particularly transepithelial/endothelial electrical resistance (TEER), is a widely adopted readout due to its non-invasive and real-time capabilities. However, substantial variability arises from differences in measurement settings, frequency selection, electrode configuration, impedance measuring techniques, and data analysis strategies. In numerous studies, TEER is approximated from single-frequency impedance magnitude measurements, which do not isolate the resistive component associated with tight junction-mediated paracellular transport but instead reflect the combined response of a coupled electrochemical system. This review clarifies impedance measuring techniques and systematically analyzes impedance-based measurement and analysis strategies for in vitro biological cell barrier integrity. We compare mono-frequency and broadband acquisition approaches, examine the influence of electrode–electrolyte interfaces, electrode geometry, and culture configuration, and evaluate equivalent circuit modeling and phase-resolved electrical impedance spectroscopy (EIS). Based on this comparison, we propose a three-level analytical hierarchy adapted to experimental objectives and instrumentation constraints. We conclude that phase-informed impedance analysis and harmonized reporting are essential to improve measurement reproducibility, inter-platform comparability, and integration of impedance-derived cell barrier assessment within NAMs-oriented research workflows. Full article

Shoseiryuto (SST) is a Kampo medicine widely used to treat respiratory diseases. We previously showed that SST attenuates lipopolysaccharide (LPS)-induced tight junction (TJ) barrier disruption in human bronchial epithelial (16HBE) cells. However, the underlying mechanisms remain unclear. This study aimed to clarify the mechanisms underlying the protective effects of SST. SST attenuated inflammatory responses (increased IL-6 protein and mRNA levels) and TJ disruption (decreased transepithelial electrical resistance, increased sodium fluorescein permeability, and decreased occludin mRNA and protein expression) induced by LPS, hydrogen peroxide (H₂O₂), tumor necrosis factor-α (TNF-α), and polyinosinic–polycytidylic acid (Poly I:C). Further analyses using the Poly I:C model confirmed that the effects of SST were comparable to those of the nuclear factor κB (NF-κB) inhibitors SC-514 and BAY11-7085. SST reduced the activation of NF-κB signaling (increased phosphorylation of NF-κB and IκB), similar to BAY11-7085. SST components, isoliquiritigenin (ILQG) and glycyrrhizin (GL), also attenuated inflammation, barrier dysfunction, and NF-κB signaling activity. These findings suggest that (1) activation of the NF-κB signaling pathway might be associated with both inflammatory responses and TJ barrier disruption; (2) SST could reduce these effects, potentially through modulation of NF-κB signaling; and (3) ILQG and GL may contribute, in part, to these activities. Overall, this study provides the first evidence suggesting that SST may exert anti-inflammatory and epithelial barrier-protective effects, possibly via the suppression of the NF-κB signaling pathway. Full article

Background: Interstitial cystitis (IC) is a debilitating lower urinary tract condition characterised by chronic inflammation of the bladder. As the aetiology remains unknown, current treatments are symptomatic, aiming to reduce inflammation and pain. Cannabidiol (CBD), the most common cannabinoid in industrial Cannabis sativa (hemp), is one of the most important pharmacologically active cannabinoids used in medicine due to its anti-inflammatory and antioxidant effects without psychoactive properties. While other cannabinoids have shown beneficial effects in animal models of IC, the impact of CBD on the urinary bladder and overall animal well-being has not been elucidated. Methods: Using a cyclophosphamide (CYP)-induced mouse model of IC, we investigated the effects of intraperitoneally administered CBD on bladder structure, function, inflammation, and animal behaviour. A multimodal approach was applied, including light and electron microscopy, immunolabeling, qPCR, transepithelial electrical resistance (TEER) measurements, behavioural testing, and monitoring of animals. Results: CBD treatment promoted the restoration of damaged urothelial structure and improved the integrity of the blood–urine barrier. Additionally, CBD exerted an anti-inflammatory effect, reducing oedema and infiltration of inflammatory cells in the bladder wall with chronic cystitis. Finally, the increased burrowing activity of CBD-treated mice suggests a benefit of CBD on overall well-being. Conclusions: Our findings suggest that CBD has a beneficial effect on the inflamed urinary bladder and could potentially serve as an adjunct treatment for patients with IC in the future. Full article

Endoscopic sinus surgery (ESS) is commonly performed to treat chronic rhinosinusitis and selected sinonasal tumors, yet postoperative complications such as neo-osteogenesis and restenosis remain frequent, largely due to impaired mucosal regeneration after extensive epithelial and bony tissue loss. Successful nasal epithelial repair requires a microenvironment that preserves cell viability, phenotype, and barrier integrity. Conventional culture substrates often lack physiological relevance or rely on animal-derived components, limiting translational applicability. In this study, we evaluated nanofibrillar cellulose (NFC) hydrogel (GrowDex^®) as a xeno-free scaffold for primary human nasal epithelial cells (NECs). NECs isolated from healthy donor tissue were characterized by immunofluorescence and qPCR for basal, goblet, and ciliated cell markers. Cells embedded in NFC were assessed for viability, cytotoxicity, epithelial morphology, and barrier function. Transepithelial electrical resistance (TEER) and FITC-dextran permeability assays were used to quantify barrier integrity and compared with collagen- and polylysine-based controls. NECs cultured in NFC maintained high viability, stable epithelial morphology, and preserved subtype-specific marker expression without detectable cytotoxicity. NFC-supported cultures demonstrated enhanced barrier formation, indicated by higher TEER values and reduced paracellular permeability relative to controls, and sustained structural integrity during extended culture. These findings identify NFC hydrogel as a biocompatible, non-animal scaffold that supports functional human nasal epithelium regeneration and may contribute to advanced tissue engineering strategies for craniofacial bone repair. Full article

Semen parameters, including sperm counts, have rapidly declined in men across the globe over the last five decades. Although this decline remains unexplained, lifestyle factors may affect male fertility. Recently, several studies highlighted a potential link between non-steroidal anti-inflammatory drug (NSAID) usage, such as naproxen and ibuprofen, and declining male fertility. However, the mechanisms by which these common analgesics affect male fertility, including their effects on the blood–testis barrier (BTB), remain poorly characterized. Utilizing an in vitro rhesus macaque non-human primate (NHP) BTB model, we demonstrate that serum levels of naproxen and ibuprofen alter the function of BTB. Following short-term naproxen and ibuprofen treatment of NHP primary Sertoli cells, we show that these NSAIDs increase the transepithelial electrical resistance, indicating an overall strengthening of the Sertoli cell junctions. Furthermore, naproxen and ibuprofen treatment alter the expression of genes involved in maintaining the BTB. Specifically, the genes that were significantly expressed in response to ibuprofen exposure were enriched for human phenotypic abnormalities linked to male factor infertility. Together, these results suggest that short-term naproxen and ibuprofen treatment disrupt the function of the BTB by altering the integrity of the Sertoli cell junctions, proposing a potential role of NSAIDs in male factor infertility. Full article

Retinal vein occlusion (RVO) is a common vascular disease that leads to vision loss due to macular edema (ME). This study investigated the role of autotaxin (ATX), a lysophospholipase D, in the pathogenesis of RVO. In mice, RVO was induced by intravenous administration of rose bengal followed by laser irradiation of retinal veins. ATX expression in the retina was evaluated using immunohistochemistry. Intravitreal ATX was administered, and retinal changes were assessed using fluorescence angiography and optical coherence tomography (OCT). In human retinal microvascular endothelial cells (HRMECs), intercellular barrier function was evaluated using transepithelial electrical resistance (TEER). In the murine RVO model, the ATX inhibitor HA130 was administered intravitreally, and retinal thickness was measured and compared using OCT. ATX expression was increased in retinal vessels in the RVO model. Intravitreal administration of ATX induced retinal edema and serous retinal detachment (SRD). ATX significantly disrupted the barrier integrity of HRMECs and promoted the expression of vascular endothelial growth factor (VEGF), which was ameliorated by HA130. Intravitreal administration of HA130 significantly reduced retinal thickening caused by retinal edema secondary to RVO and the elevated expression of intercellular adhesion molecule (ICAM)-1 in the retina. These findings suggest that ATX plays a critical role in RVO-induced ME by disrupting endothelial barrier integrity, potentially through the upregulation of VEGF in retinal endothelial cells and subsequent ICAM-1 upregulation in the retina. Full article

The mycotoxin deoxynivalenol (DON) is a common contaminant found in swine diets, causing decreased growth performance and poor health. Additionally, F18 enterotoxigenic E. coli is a leading cause of post-weaning diarrhea. Nursery pigs are often exposed to each of them after weaning; however, it is unknown what impact the combination of these stressors has on gastrointestinal health. Therefore, the objective of this study was to investigate the effect of pre-exposure to DON on the response of intestinal porcine epithelial cells (IPEC-J2) to challenge with enterotoxigenic F18 E. coli. Four groups were compared: Control (untreated cells), DON (cells treated with 0.5 μM DON for 24 h), F18 E. coli (multiplicity of infection 5:1, varied duration) and DON + E. coli (DON treatment with subsequent E. coli infection). Gene expression of IL-8, IL-6 and TNFα was significantly increased in cells infected with E. coli for 3 h vs. uninfected cells (p < 0.0001, p < 0.0001 and p < 0.0001, respectively). There was an interactive effect between DON and E. coli on IL-8 gene expression; cells pretreated with DON before E. coli infection had a higher expression of IL-8 than those not pretreated (p < 0.05). The concentration of IL-8 protein was significantly increased by E. coli (p < 0.0001). Claudin 1 and Occludin protein abundance were reduced by E. coli as measured by Western blot. Cytotoxicity was increased by E. coli vs. Control (p < 0.05). Pretreatment with DON increased the amount of E. coli that adhered to IPEC-J2 cells (p < 0.01) 30 min post-infection. FITC-dextran passage was increased in the DON + E. coli treatment vs. E. coli alone (p < 0.0001). Transepithelial electrical resistance (TEER) was decreased by DON when compared to untreated cells at 0 h (p < 0.0001). Similarly, DON + E. coli exhibited lower TEER vs. E. coli alone at 2 h post-infection (p < 0.0001). Taken together, these results indicate that DON pre-exposure increased the severity of E. coli infection on endpoints such as barrier permeability and E. coli adhesion. Full article