Increased Barrier Function Research Articles

Candida tropicalis-derived vitamin B3 exerts protective effects against intestinal inflammation by promoting IL-17A/IL-22-dependent epithelial barrier function

ABSTRACT Candida tropicalis-a prevalent gut commensal fungus in healthy individuals – contributes to intestinal health and disease. However, how commensal C. tropicalis influences intestinal homeostasis and barrier function is poorly understood. Here, we demonstrated that the reference strain of C. tropicalis (MYA-3404) ameliorated intestinal inflammation in murine models of chemically induced colitis and bacterial infection. Intestinal colonization of C. tropicalis robustly upregulated the expression of IL-17A and IL-22 to increase barrier function and promote proliferation of intestinal epithelial cells in the mouse colon. Metabolomics analysis of fecal samples from mice colonized with C. tropicalis revealed alterations in vitamin B3 metabolism, promoting conversion of nicotinamide to nicotinic acid. Although nicotinamide worsened colitis, treatment with nicotinic acid alleviated disease symptoms and enhanced epithelial proliferation and Th17 cell differentiation. Oral gavage of C. tropicalis mitigated nicotinamide-induced intestinal dysfunction in experimental colitis. Blockade of nicotinic acid production with nicotinamidase inhibitors lowered the protective effects against colitis in mice treated with C. tropicalis. Notably, a clinical C. tropicalis strain isolated from patients with candidemia lacked the protective effects against murine colitis observed with the reference strain. Together, our results highlight a novel role for C. tropicalis in resolving intestinal inflammation through the modulation of vitamin B3 metabolism.

Unexpected and Synergistical Effects of All-Trans Retinoic Acid and TGF-β2 on Biological Aspects of 2D and 3D Cultured ARPE19 Cells.

Objectives: To study the effects of all-trans retinoic acid (ATRA) on TGF-β2-induced effects of human retinal pigment epithelium cells under normoxia and hypoxia conditions. Methods: Two-dimensionally (2D) and three-dimensionally (3D) cultured ARPE19 cells were subjected to cellular functional analyses by transepithelial electrical resistance (TEER) and an extracellular flux assay (2D), measurement of levels of reactive oxygen species (ROS), gene expression analyses of COL1, αSMA, Zo-1, HIF1α, and PGC1α (2D), and physical property analyses (3D). Results: Under a normoxia condition, treatment with 100 nM ATRA substantially decreased barrier function regardless of the presence of 5 ng/mL TGF-β2 in 2D ARPE19 monolayer cells. Under a hypoxia condition, treatment with ATRA conversely increased barrier function, but the effect was masked by a marked increase in effects induced by TGF-β2. Although ATRA alone did not affect cellular metabolism and ROS levels in 2D ARPE cells, treatment with ATRA under a hypoxia condition did not affect ROS levels but shifted cellular metabolism from mitochondrial respiration to glycolysis. The changes of cellular metabolism and ROS levels were more pronounced with treatment of both ATRA and TGF-β2 independently of oxygen conditions. Changes in mRNA expressions of some of the above genes suggested the involvement of synergistical regulation of cellular functions by TGF-β2 and hypoxia. In 3D ARPE spheroids, the size was decreased and the stiffness was increased by either treatment with TGF-β2 or ATRA, but these changes were unexpectedly modulated by both ATRA and TGF-β2 treatment regardless of oxygen conditions. Conclusions: The findings reported herein indicate that TGF-β2 and hypoxia synergistically and differentially induce effects in 2D and 3D cultured ARPE19 cells and that their cellular properties are significantly altered by the presence of ATRA.

Development of a Static Avascular and Dynamic Vascular Human Skin Equivalent Employing Collagen/Keratin Hydrogels.

One of the primary complications in generating physiologically representative skin tissue is the inability to integrate vasculature into the system, which has been shown to promote the proliferation of basal keratinocytes and consequent keratinocyte differentiation, and is necessary for mimicking representative barrier function in the skin and physiological transport properties. We created a 3D vascularized human skin equivalent (VHSE) with a dermal and epidermal layer, and compared keratinocyte differentiation (immunomarker staining), epidermal thickness (H&E staining), and barrier function (transepithelial electrical resistance (TEER) and dextran permeability) to a static, organotypic avascular HSE (AHSE). The VHSE had a significantly thicker epidermal layer and increased resistance, both an indication of increased barrier function, compared to the AHSE. The inclusion of keratin in our collagen hydrogel extracellular matrix (ECM) increased keratinocyte differentiation and barrier function, indicated by greater resistance and decreased permeability. Surprisingly, however, endothelial cells grown in a collagen/keratin extracellular environment showed increased cell growth and decreased vascular permeability, indicating a more confluent and tighter vessel compared to those grown in a pure collagen environment. The development of a novel VHSE, which incorporated physiological vasculature and a unique collagen/keratin ECM, improved barrier function, vessel development, and skin structure compared to a static AHSE model.

PSIV-30 Exploring the Prebiotic Activities of Proanthocyanidins on a Platform Using the Three-Dimensionally (3D)-Cultured Organoids

Abstract Using antibiotics, the antimicrobial substance active against bacteria and promoting growth efficiency, in feedstuffs and food supply has been attracting great attention due to its side effects and contribution to antibiotic resistance. Therefore, exploring talternatives to antibiotics is of great significance and urgent need for human health and animal industries with a sustainable high efficiency. The objective of this study is to evaluate the biological and medicinal activities of the monomers of proanthocyanidins (PAs), such as epicatechin, epigallocatechin gallate, and flavanols such as quercetin, isoquercetrin, and rutin generated from engineered plants. The evaluations were performed in intestinal organoids isolated from ileum of neonatal piglets. The organoids after expended in vitro were incubated with or without the candidate compounds for 24 hours, and then treated with or without polyinosinic-polycytidylic acid [Poly (I:C), 10 µg/mL] for another 24 hours, a synthetic analog of double-stranded RNA (can induce a molecular pattern associated with viral infections). Cell proliferation, barrier function, toll-like receptor pathway and apoptosis as well as organic cation transporters were assessed by measuring the abundance of the corresponding genes. Concentration gradient (0 to 200 µM) measurements showed that isoquercetrin and epigallocatechin gallate might stimulate the intestinal cell proliferation, promote the uptake of L-carnitine, and increase barrier function and mucin secretion (P < 0.05). Epigallocatechin gallate and epicatechin might affect the inflammation responses via modifying expression of Interleukins but not induce apoptosis. Interactions between the examined these compounds and Poly (I: C) were not observed (P > 0.05), but the influence on the challenged pattern were tested for some of the measured genes (P < 0.05). Based on the data collected from this in vitro study, we conclude that epigallocatechin gallate is a potential PA monomer with all prebiotic characteristics and its applicable values in feedstuff and food supply should be studied in vivo studies in domestic (food) animals with and without antigen challenges. Supported by NC Biotechnology Center project (1107)2022-3082 and the North Carolina Agricultural Research Hatch Projects 02780.

Heterogenous morphogenesis of Caco-2 cells reveals that flow induces three-dimensional growth and maturation at high initial seeding cell densities.

Here, we introduce a customized hanging insert fitting a six-well plate to culture Caco-2 cells on hydrogel membranes under flow conditions. The cells are cultured in the apical channel-like chamber, which provides about 1.3 dyn/cm2 shear, while the basolateral chamber is mixed when the device is rocked. The device was tested by investigating the functional impact of the initial seeding density in combination with flow applied at confluency. The low seeding density cultures grew in two dimensional (2D) irrespective of the flow. Flow and higher seeding density resulted in a mixture of three dimensional(3D) structures and 2D layers. Static culture and high cell seeding density resulted in 2D layers. The flow increased the height and ZO-1 expression of cells in 2D layers, which correlated with an improved barrier function. Cultures with 3D structures had higher ZO-1 expression than 2D cultures, but this did not correlate with an increased barrier function. 2D monolayers in static and dynamic cultures had similar morphology and heterogeneity in the expression of Mucin-2 and Villin, while the 3D structures had generally higher expression of these markers. The result shows that the cell density and flow determine 3D growth and that the highest barrier function was obtained with low-density cultures and flow.

Rhinovirus increases Moraxella catarrhalis adhesion to the respiratory epithelium.

Rhinovirus causes many types of respiratory illnesses, ranging from minor colds to exacerbations of asthma. Moraxella catarrhalis is an opportunistic pathogen that is increased in abundance during rhinovirus illnesses and asthma exacerbations and is associated with increased severity of illness through mechanisms that are ill-defined. We used a co-infection model of human airway epithelium differentiated at the air-liquid interface to test the hypothesis that rhinovirus infection promotes M. catarrhalis adhesion and survival on the respiratory epithelium. Initial experiments showed that infection with M. catarrhalis alone did not damage the epithelium or induce cytokine production, but increased trans-epithelial electrical resistance, indicative of increased barrier function. In a co-infection model, infection with the more virulent rhinovirus-A and rhinovirus-C, but not the less virulent rhinovirus-B types, increased cell-associated M. catarrhalis. Immunofluorescent staining demonstrated that M. catarrhalis adhered to rhinovirus-infected ciliated epithelial cells and infected cells being extruded from the epithelium. Rhinovirus induced pronounced changes in gene expression and secretion of inflammatory cytokines. In contrast, M. catarrhalis caused minimal effects and did not enhance RV-induced responses. Our results indicate that rhinovirus-A or C infection increases M. catarrhalis survival and cell association while M. catarrhalis infection alone does not cause cytopathology or epithelial inflammation. Our findings suggest that rhinovirus and M. catarrhalis co-infection could promote epithelial damage and more severe illness by amplifying leukocyte inflammatory responses at the epithelial surface.

Strengthening of the barrier function in human telomerase reverse transcription (hTERT) immortalized corneal and conjunctival epithelium by double-stranded RNA

To investigate the response to polyinosinic:polycytidylic acid [poly(I:C)], a double-stranded RNA Toll-like receptor 3 agonist that mimics viral infection, in the barrier function of two established human telomerase reverse transcriptase-immortalized cell lines, termed HCLE for the human corneal-limbal epithelial line and HCjE for the human conjunctival-epithelial line. In this study, HCLE and HCjE cells were used to evaluate the underlying mechanism of epithelial-cell barrier function regulation. Briefly, HCLE and HCjE cells were first cultured on 12-well Transwell® (Corning®) filter-plates, and reverse transcription-polymerase chain reaction, western blotting, and immunohistochemical examinations were then performed to assess tight junction (TJ)-related protein expression and cellular distribution. Next, the barrier function of the cells was measured via transepithelial electrical resistance (TEER) and paracellular molecular flux. The cells were then stimulated with poly(I:C) and the TEER and TJ-related protein expressions were analyzed. Similar to that in in vivo epithelium, the expression of claudin (CLDN) subtypes CLDN-1, -4, and -7 was observed in the HCLE and HCjE cells, and the barrier function in the HCLE cells was tighter than that in the HCjE cells. Post stimulation with poly(I:C), TEER of the HCLE and HCjE cells increased in a dose- and time-dependent manner, the production of TJ-related protein mRNA and CLDN-4 protein were elevated, and the barrier function of the HCLE and HCjE cells increased, thus possibly indicating that the increased barrier function is a defense mechanism against viral infection.

Human iPSC colon organoid function is improved by exposure to fecal fermentates.

The host–microbe interaction is critical for intestinal homeostasis. By‐products from microbial metabolism of unabsorbed dietary components have been studied increasingly as potential contributors to health and disease. In vitro fermentation systems provide a way to simulate microbial activity and by‐product production of the colon using human fecal samples. Objectives of the study were to determine how clarified supernatants from two different fermentation conditions affect markers of cell proliferation, differentiation, barrier function, and immune function in a human‐induced pluripotent (iPSC) colon organoid model. SCFA and BCFA's of the supernatants were analyzed and were similar to known in vivo concentrations. Molecular results showed 25% of the clarified supernatant from batch fermentation led to a more physiological intestinal phenotype including increased markers of differentiation, including alkaline phosphatase, chromogranin A, SCFA transport monocarboxylate transporter‐1, (6.2‐fold, 2.1‐fold, and 1.8‐fold, respectively; p < 0.05). Mucin production (mucin‐2, mucin‐4) was increased in cells treated with 25% supernatant, as observed by confocal microscopy. In addition, increased tight junction expression (claudin‐3) was noted by immunofluorescence in 25% supernatant‐ treated cells. A dose–response increase in barrier function was observed over the 72‐h time course, with a twofold increase in transepithelial electrical resistance (TER) in the 25% group compared to the control group (p < 0.05). To further investigate host effects, clarified supernatants from a continuous multistage fermentation representing the ascending (AC), transverse (TC), and descending (DC) colonic domains were utilized and some regional differences were observed including increased markers of inflammation (IL‐1β, 6.15 pg/ml; IL‐6, 27.58 pg/ml; TNFα, 4.49 pg/ml; p < 0.05) in DC‐treated samples only. Overall, clarified supernatants represent a valuable model to examine effects of microbial by‐products on host intestinal development and function and future efforts will be designed to further understand microbial communities and metabolites, along with additional host response measures.

Calcium-sensing receptor protects intestinal integrity and alleviates the inflammatory response via the Rac1/PLCγ1 signaling pathway

This study aimed to test the hypothesis that the calcium-sensing receptor (CaSR) can protect intestinal epithelial barrier integrity and decrease inflammatory response mediated by the Ras-related C3 botulinum toxin substrate 1 (Rac1)/phospholipase Cγ1 (PLC-γ1) signaling pathway. IPEC-J2 monolayers were treated without or with TNF-α in the absence or presence of CaSR antagonist (NPS 2143), CaSR overexpression, and Rac1 silencing, PLCγ1 silencing or spermine. Results showed that spermine increased transepithelial electrical resistance (TER), tight junction protein levels, the protein concentration of Rac1/PLC-γ1 signaling pathway, and decreased paracellular permeability in the presence of TNF-α. NPS2143 inhibited spermine-induced change in above-mentioned parameters. CaSR overexpression increased TER, the levels of tight junction proteins and the protein concentration of CaSR, phosphorylated PLCγ1, Rac1, and IP3, and decreased paracellular permeability and contents of interleukin-8 (IL-8) and TNF-α after TNF-α challenge. Rac1 and PLCγ1 silencing inhibited CaSR-induced increase in barrier function and the protein concentration of phosphorylated PLCγ1, Rac1, and IP3, and decrease in contents of IL-8 and TNF-α after TNF-α challenge. These results suggest that CaSR activation protects intestinal integrity and alleviates the inflammatory response by activating Rac1 and PLCγ1 signaling after TNF-α challenge, and spermine can maintain barrier function via CaSR/Rac1/PLC-γ1 pathway.

A blend of 3 mushrooms dose-dependently increases butyrate production by the gut microbiota.

The gut microbiota has been indicated to play a crucial role in health and disease. Apart from changes in composition between healthy individuals and those with a disease or disorder, it has become clear that also microbial activity is important for health. For instance, butyrate has been proven to be beneficial for health, because, amongst others, it is a substrate for the colonocytes, and modulates the host's immune system and metabolism. Here, we studied the effect of a blend of three mushrooms (Ganoderma lucidum GL AM P-38, Grifola frondosa GF AM P36 and Pleurotus ostreatus PO AM-GP37)) on gut microbiota composition and activity in a validated, dynamic, computer-controlled in vitro model of the colon (TIM-2). Predigested mushroom blend at three doses (0.5, 1.0 and 1.5 g/day of ingested mushroom blend) was fed to a pooled microbiota of healthy adults for 72 h, and samples were taken every day for microbiota composition (sequencing of amplicons of the V3-V4 region of the 16S rRNA gene) and activity (short-chain fatty acid (SCFA) production). The butyrate producing genera Lachnospiraceae UCG-004, Lachnoclostridium, Ruminococcaceae UCG-002 and Ruminococcaceae NK4A214-group are all dose-dependently increased when the mushroom blend was fed. Entirely in line with the increase of these butyrate-producers, the cumulative amount of butyrate also dose-dependently increased, to roughly twice the amount compared to the control (medium without mushroom blend) on the high-dose mushroom blend. Butyrate proportionally made up 53.1% of the total SCFA upon feeding the high-dose mushroom blend, compared to 27% on the control medium. In conclusion, the (polysaccharides in the) mushroom blend led to substantial increase in butyrate by the gut microbiota. These results warrant future mechanistic research on the mushroom blend, as butyrate is considered to be one of the microbial metabolites that contributes to health, by increasing barrier function and modulating inflammation.

Human iPSC Colonoid Function is Improved by Exposure to Fecal Fermentates

The host-microbe interaction is critical for intestinal homeostasis. By-products from microbial metabolism of unabsorbed dietary components have been studied increasingly as potential contributors to health and disease. In vitro fermentation systems provide a way to simulate microbial activity and by-product production of the colon using human fecal samples. Objectives of the study were to determine how clarified supernatants from two different fermentation conditions affect markers of cell proliferation, differentiation, barrier function, and immune function in a human induced pluripotent (iPSC) colon organoid model. Short-chain and branch-chain fatty acid concentrations of the supernatants were analyzed and were similar to known in vivo concentrations. Molecular results showed 25% of the clarified supernatant from batch fermentation led to a more physiological intestinal phenotype including increased markers of differentiation, including alkaline phosphatase, chromogranin-A, SCFA transport monocarboxylate transporter-1, (6.2-fold, 2.1-fold, 1.8-fold, respectively; P<0.05). Mucin production (mucin-2, mucin-4) was increased in cells treated with 25% supernatant, as observed by confocal microscopy. In addition, increased tight junction expression (claudin-3) was noted by immunofluorescence in 25% supernatant treated cells. A dose-response increase in barrier function was observed over the 72-hour time course, with a 2-fold increase in transepithelial electrical resistance (TER) in the 25% group compared to the control group (P<0.05). To further investigate host effects, clarified supernatants from a continuous multi-stage fermentation representing the ascending (AC), transverse (TC), and descending (DC) colonic domains were utilized and some regional differences were observed including increased markers of inflammation (IL-1β, 6.15pg/mL; IL-6, 27.58pg/mL; TNFα, 4.49pg/mL; P < 0.05) in DC treated samples only. Overall, clarified supernatants represent a valuable model to examine effects of microbial by-products on host intestinal development and function and future efforts will be designed to further understand microbial communities and metabolites, along with additional host response measures.

TRPA1 function in human pulmonary fibroblasts

Transient receptor potential ankyrin 1 (TRPA1) is a non-selective Ca2+ permeable cation channel. While TRPA1 was mostly studied in neuronal cells, it was originally cloned from cultured human lung fibroblasts. TRPA1-mediated Ca2+ entry is evoked by exposure to several chemicals including allyl isothiocyanate (AITC) and inhaled components of cigarette smoke, suggesting a possible role of TRPA1 in progression of lung disease. However, a protective effect of TRPA1 activation in the development of cardiac fibrosis was proposed. Yet, the function of TRPA1 in transforming growth factor β1 (TGF-β1)-driven fibroblast to myofibroblast differentiation as well as the development of pulmonary fibrosis remains elusive. TRPA1 expression and function was analyzed in cultured primary human pulmonary fibroblasts (HPF) obtained from three different donors before and after incubation with TGF-β1. Transcriptome sequencing, qRT-PCR and immunoblotting were used to identify target genes on mRNA and protein levels. TRPA1 specific siRNAs were established to assess the role of the channel in cell function during fibroblast myofibroblasts differentiation. TRPA1 mRNA is highly expressed in HPF and levels were significantly reduced after adding TGF-β1. Expression of fibrosis markers, e.g. alpha smooth muscle actin (αSMA), plasminogen activator inhibitor (PAI), fibronectin (FN1) and collagen (Col1a1), was increased after down-regulation of TRPA1-mRNA by siRNA targeting in HPF. Moreover, TGF-β1 treatment of HPFs reduced Ca2+ entry evoked by the TRPA1 activator AITC, while increasing barrier function and contractile characteristics of the cells. Effects of siRNA-mediated knock-down of TRPA1 on cell contraction, migration and resistance of HPF will be quantified and compared to TGF-β1-induced fibroblast myofibroblast differentiation. Our results suggest an inhibitory function of TRPA1 channels in TGF-β1-driven fibroblast to myofibroblast differentiation. Therefore, activation of TRPA1 channels might protect from the development of pulmonary fibrosis in patients

Cinnamon bark oil and coconut oil emulsions modified small intestinal motility and barrier function in laying hens in an ex vivo experiment

ABSTRACT 1. Plant extracts and oils are supplemented in diets for chickens due to their antimicrobial capacities; however, little information exists whether they influence intestinal motility and barrier function. 2. The present study aimed to determine the effect of increasing levels of cinnamon bark oil (CBO; 0%, 0.038%, 0.076% and 0.151%) and coconut oil emulsions prepared with soy and sunflower lecithin on the contractile function of enteric wall muscles in the jejunum and ileum and jejunal barrier function in laying hens. 3. For testing muscle contraction, mid-jejunal and ileal segments (n = 4 each per hen) from four laying hens were placed in a longitudinal orientation into isolated organ baths filled with Krebs buffer and fastened to force transducers. Muscle segments were induced to contract with acetylcholine and the effects of the oil emulsions on contraction were measured. 4. For barrier function, distal jejunal pieces were stripped of serosa before mounting into Ussing chambers and recording changes in short-circuit current (ISC) and transepithelial tissue conductivity (GT) before and after addition of the respective emulsion. 5. The CBO decreased the muscle tone, representing a relaxation of on average 36.2% and 42.6% for the jejunum and ileum, respectively, compared to before the addition (P < 0.001). Moreover, CBO linearly decreased the ISC and GT of the jejunal mucosa, indicating a greater absorption of anions and increased barrier function (P < 0.001). Only the coconut oil-sunflower lecithin emulsion relaxed the muscles, whereas both coconut oil-lecithin emulsions increased the ISC but reduced the GT of the jejunal mucosa, which suggested an increased cation absorption and decreased paracellular permeability, respectively (P < 0.05). 6. In conclusion, CBO and coconut oil-lecithin emulsions showed the potential to increase jejunal barrier function, whereas CBO may be more efficacious to slow down digesta passage in the small intestine.

Structure of an Inner Membrane Protein Required for PhoPQ-Regulated Increases in Outer Membrane Cardiolipin.

The Salmonella enterica subsp. enterica serovar Typhimurium PhoPQ two-component system is activated within the intracellular phagosome environment, where it promotes remodeling of the outer membrane and resistance to innate immune antimicrobial peptides. Maintenance of the PhoPQ-regulated outer membrane barrier requires PbgA, an inner membrane protein with a transmembrane domain essential for growth, and a periplasmic domain required for PhoPQ-activated increases in outer membrane cardiolipin. Here, we report the crystal structure of cardiolipin-bound PbgA, adopting a novel transmembrane fold that features a cardiolipin binding site in close proximity to a long and deep cleft spanning the lipid bilayer. The end of the cleft extends into the periplasmic domain of the protein, which is structurally coupled to the transmembrane domain via a functionally critical C-terminal helix. In conjunction with a conserved putative catalytic dyad situated at the middle of the cleft, our structural and mutational analyses suggest that PbgA is a multifunction membrane protein that mediates cardiolipin transport, a function essential for growth, and perhaps catalysis of an unknown enzymatic reaction.IMPORTANCE Gram-negative bacteria cause many types of infections and have become increasingly resistant to available antibiotic drugs. The outer membrane serves as an important barrier that protects bacteria against antibiotics and other toxic compounds. This outer membrane barrier function is regulated when bacteria are in host environments, and the protein PbgA contributes significantly to this increased barrier function by transporting cardiolipin to the outer membrane. We determined the crystal structure of PbgA in complex with cardiolipin and propose a model for its function. Knowledge of the mechanisms of outer membrane assembly and integrity can greatly contribute to the development of new and effective antibiotics, and this structural information may be useful in this regard.

58 Functional nutrition to modulate the immune response

Abstract Growing concerns about antibiotic resistance coupled with recent legislation limiting in-feed antibiotic use in livestock feed has led to a resurgence of interest in plant-based extracts, prebiotics/probiotics, and other nutraceutical compounds with immune-modulating properties. Consumer preference for functional ingredients in their own food as well as feed for their pets or livestock has created a niche for development of feed additives with bioactive properties with the potential to improve health through their ability to regulate inflammation and modulate microbial communities. For example, dietary omega-3 fatty acids have been documented to reduce inflammation through altering the fatty acid composition of immune cells, shifting immune cell function, and reducing inflammatory lipid mediator and cytokine production. Dietary probiotic supplementation allows an intimate interaction between the gut mucosa and the largest concentrated population of the host’s immune cells, the mucosal immune system. Probiotics have been shown to modulate the inflammatory response through interaction with intestinal epithelial cells, M-cells in Peyer’s patches, innate immune cells such as dendritic and other antigen-presenting cells, and increasing barrier function through increased mucus and antibody production. Other feedstuffs such as green tea components (epigallocatechin-3-gallate, EGCG) interact with neutrophils and macrophages to limit cellular migration and inflammatory molecule production to reduce inflammation. A wealth of information detailing mechanistic outcomes exists in mouse literature and human cell lines, while livestock and companion animal literature is an untapped area for future work. An emphasis on research aimed at a more molecular, mechanistic understanding of currently available feed additives will lead to the improvement of existing additives and development of new additives for use in livestock and companion animal feed.

A Randomized Pilot Clinical Assessment Of Three Skincare Regimens On Skin Conditions In Infants.

IntroductionFew data are available on the comparison between the effects on infant skin of skin care products and those of water alone.Patients and methodsIn this single-center, evaluator-blind, parallel-group pilot study, healthy infants were randomized to near-daily washing for 12 weeks (starting in the summer and finishing in the winter months) with a mild liquid baby wash followed by use of baby lotion (wash+lotion), water followed by baby lotion (water+lotion), or water alone. Clinical and instrumental assessments of skin moisturization and barrier function were made.ResultsAs expected the skin condition in all groups was affected by the change of the season. The skin of infants in all groups was mildly deteriorated (clinical grading) and with reduced moisture levels and increased barrier function. Instrumental measurements indicated that skin moisture and barrier function were better maintained in the wash+lotion and water+lotion groups than in the water-only group at week 12. Clinical assessment scores increased slightly over 12 weeks in all groups (P<0.05). At week 12, the wash+lotion group (n = 44) had significantly less change from baseline in overall skin condition and softness (lower scores) than did the water+lotion (n = 43) or water-only (n = 43) groups. The wash+lotion regimen maintained stable erythema and rash scores with lower mean values over time than in the other groups.ConclusionA regimen of a liquid baby wash and a baby skin lotion for 12 weeks resulted in less detrimental changes in instrumental and clinical measures of skin than using water and lotion or water alone.

Abstract 3459: PKD1 regulates susceptibility to ulcerative colitis and colorectal cancer

Abstract Compromised integrity of the epithelial barrier function of colon tissue associated with inflammatory bowel diseases (IBDs) or arising from tumor-elicited inflammation (TEI) are associated with and support formation of colorectal cancer (CRC). Apical tight junction (TJ) proteins, including multiple specific claudins, are critical in regulating TJ barrier function and paracellular permeability. Changes in TJ composition in the kidney are strongly linked to the etiology of autosomal dominant polycystic kidney disease (ADPKD), with ADPKD-inducing mutations in PKD1 causing non-leaky barriers that can withstand high hydrostatic pressure within renal cysts a hallmark of this common (1 in 500) inherited disease. Intriguingly, a large population study has found a decreased incidence of CRC in ADPKD patients. Based on these and other suggestive data, we hypothesized that loss of PKD1 would hinder development of ulcerative colitis and initiation of colitis associated cancer, based on reorganizing TJs and TEI in the colon. To evaluate the impact of Pkd1 loss on colon barrier function, we treated 10-12 week old wt or Pkd1fl/fl mice with tamoxifen-induced, Cre expression from the CreERT2 cassette for 5 days with 2.5% DSS in drinking water to induce acute colitis, compared to a no-DSS control group. For the wtcohort, treatment with DSS increased orally gavaged FITC-dextran detectable in serum versus controls. In contrast, no Pkd1-/- mice showed a similar DSS-dependent response to FITC-dextran, suggesting reinforced colon barrier function; further, histopathological assessment confirmed less DSS-induced damage in Pkd1fl/fl mice. Further, based on immunofluorescence (IF) analysis of tissue sections, claudins 4 and 7 associated with increased barrier function) strongly elevated in the colonic epithelium of Pkd1fl/fl versus wt mice, with the expressed proteins having consistently greater localization to cell junctions in Pkd1fl/fl versus wt mice. We also investigated the formation of CRC tumors, using a CDX2-ERT2/Cre model for tamoxifen-induced loss of Apc and/or Pkd1 in the colon to compare tumorigenesis in the Apcfl/fl, Apcfl/fl Pkd1fl/fl, and Apcfl/flPkd1fl/+ genotypes. We observed a highly significant progressive increase in the number and size of Apc mutation-induced tumors based on retention of the Pkd1 gene. Preliminary qRT-PCR analysis of these tumors shows that a Pkd1fl/fl genotype substantially increases CLDN4 in normal and tumor tissue, and decreases TNFα expression in tumors, suggesting reduced inflammation. This work and extended mechanistic characterization identifies PKD1 as a vital regulator of signaling systems already associated with colitis and CRC. Understanding the role of PKD1 and its effectors may provide useful information to genetic counselors assessing risk of IBD and CRC, and suggest therapeutic strategies. Citation Format: Anna S. Nikonova, Anna Kiseleva, Ilya Serebriiskii, Sergei Grivennikov, Erica A. Golemis. PKD1 regulates susceptibility to ulcerative colitis and colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3459.

RGal Increases Intestinal Epithelial Barrier Function in a PKC‐Dependent Manner and Drives an Inflammatory Gene Expression Profile

BackgroundLoss of intestinal epithelial barrier function has been linked to inflammatory bowel disease (IBD). We previously showed that the dietary fibre, rhamnogalacturonan (RGal), reduces inflammation in a murine model of DSS colitis. Additionally, apical treatment of Caco2 human intestinal epithelial cells with RGal increases transepithelial electrical resistance (TER) and accelerates wound‐healing, but the underlying mechanisms remain unknown.AimsWe aimed to determine the mechanisms of the RGal mediated increase in epithelial barrier function. (1) Given the ability of PKC to modulate barrier permeability we aimed to determine the role of PKC in the RGal‐mediated increase in epithelial barrier function. (2) We aimed to determine changes in gene expression following RGal treatment.Methods(1) To determine the role of PKC in the RGal‐induced increase in epithelial barrier function, Caco2 monolayers were mounted in Ussing Chambers, pre‐treated with pan protein kinase C (PKC), PKCz‐specific, or classical PKC inhibitors (GFX, PKCz pseudosubstrate or Go6976 respectively) and then treated with RGal. Change in TER and FITC‐dextran flux in response to RGal were assessed. (2) To determine the transcriptionally dependent effects of RGal on epithelial barrier function, Caco2 monolayers were treated apically for 6, 12 and 24h with RGal and RNAseq was performed. Genes with changes in expression more than 3‐fold were entered into Enrichr for pathway analysis. In order to confirm changes in gene expression from RNAseq, a multi‐array immunoassay was performed.Results(1) RGal (1 mg/mL) reduced FITC‐dextran flux by 52.0% (n=5, p&lt;0.05) 30 min post‐treatment. The effect of RGal on macromolecular permeability was reduced with GFX pre‐treatment (500 nM) by 75.3% (n=5, p&lt;0.01). However, the ability of GFX to block the RGal‐mediated increase in barrier function was not mimicked in monolayers pre‐treated with PKCz pseudosubstrate inhibitor (10 mM, n=6) or Go6976 (10 nM, n=5). (2) While RGal had no significant effect on tight junction gene expression 6h post‐treatment, it upregulated the expression of inflammatory response genes including neutrophil regulatory genes such as CXCL8. Consistent with gene expression data, multiplex protein assay revealed an upregulation in CXCL8 family chemokines and G‐CSF as early as 2h in cell lysates and 6h in the supernatant.ConclusionsThe RGal‐mediated increase in intestinal epithelial barrier function is dependent on PKC. Transcriptionally, RGal upregulates the expression of inflammatory mediators such as CXCL8. Understanding the mechanism of the RGal‐induced increase in intestinal epithelial barrier function may allow for leverage of these mechanisms to treat IBD.Support or Funding InformationProject supported by the NSERC (Canada), J.S. supported by an UGREF from the American Physiological Society.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Determining the effect of the WNT/b‐catenin pathway on the ischemic blood‐brain barrier in vitro and in vivo

The blood‐brain barrier (BBB) is a selectively permeable barrier made up of tight junctions formed by endothelial cells that separates the circulating blood from the brain extracellular fluid. The primary function of the BBB is to limit the movement of xenobiotics from the blood to the brain. In the event of an ischemic stroke, the BBB opens allowing water and ions to enter the brain, leading to excitotoxicity and edema formation. Targeting such opening of the barrier following ischemic stroke has become a focus in current stroke studies. It has been shown that the Wnt/b‐catenin pathway is important for barrier formation during embryonic development, therefore, we hypothesized that activation of this pathway following ischemic stroke would attenuate barrier dysfunction. Brain microvascular endothelial cells (BMECs) derived from iPSCs were cultured and placed in ischemic stress for 6hrs, followed by an 18‐hour period of re‐oxygenation. Wnt small molecule activators (CHIR99021 and SB‐216763) and inhibitors (XAV939, IWP‐4, IWR‐1) were introduced at different time points of differentiation, during ischemia, and during re‐oxygenation. Transendothelial Electrical Resistance (TEER) and permeability were performed to assess barrier integrity following re‐oxygenation. For in vivo studies, C57BL mice were subjected to one‐hour ischemia by MCAO. At the time of re‐oxygenation, mice were dosed with CHIR99021 (IP; 30mg/kg). 24‐hours post‐MCAO, TTC staining on brains was performed to determine infarct size and edema ratio. The results of the in vitro studies have shown that activation of the Wnt pathway during re‐oxygenation results in increased barrier function, suggesting that the Wnt pathway is a potential target for post‐stroke therapy.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A Direct Effect of Sex Hormones on Epithelial Barrier Function in Inflammatory Bowel Disease Models.

Background: Pregnancy is often described as an immune-tolerant state, and a disease modulatory role for pregnancy on inflammatory bowel disease (IBD) has been suggested. The direct effect of estrogen and progesterone on the intestinal epithelial barrier is underexplored. We investigated the direct consequences of these pregnancy hormones on barrier cells and their function. Methods: We used IBD patient-derived inflammatory organoid models and 2D cell lines models. Epithelial barrier function was analyzed by measuring transepithelial electrical resistance; wound closure was determined by scratch assay; and cell viability was measured by MTT assays. Pro-inflammatory cytokine production was determined by enzyme-linked immunosorbent assays. Molecular modulation of endoplasmic reticulum (ER) stress induced by tunicamycin was studied by western blot analysis of the ER stress markers GRP78, CHOP and p-IRE1. Results: Progesterone and estrogen improved wound healing and epithelial barrier function in intestinal epithelial cells via upregulation of tight junction proteins. Furthermore, these sex hormones significantly reduced ER-stress and reduce pro-inflammatory cytokine production in intestinal epithelial models. Conclusion: Our study shows that estrogen and progesterone alleviate ER stress, decrease pro-inflammatory cytokine production, stimulate wound healing, and increase barrier function of epithelial cells. Combined, these data suggest that pregnancy hormones can have beneficial effects on disease activity by positively modulating the intestinal epithelial lining.