Epithelial Attachment Research Articles

Human Neutrophil Defensins and Their Effect on Epithelial Cells

The aims of the present study include: 1) to localize human neutrophil defensin-1 (HNP-1) through HNP-3 in gingiva and in neutrophil extract-treated epithelial cell monolayers; 2) to determine the effects of HNP-1 on the epithelial cell viability, attachment, and spreading; and 3) to analyze the effect of HNP-1 on the bacterial adherence to epithelial cells. For localization of HNP-1 through HNP-3 in gingival tissue and in preincubated cell monolayers, immunohistochemical and immunocytochemical methods were used. Viability and proliferation of epithelial cells were determined with commercial kits after incubating the keratinocytes with different HNP-1 concentrations (low, 1 to 5 μg/mL; moderate, 10 μg/mL; high, 20 to 50 μg/mL). Attachment and spreading of keratinocytes on fibronectin-coated surfaces in the presence of HNP-1 were evaluated under microscope. Attachment of Fusobacterium nucleatum ATCC25586 and Prevotella intermedia ATCC25611 on keratinocytes preincubated with HNP-1 were determined with a standard antibiotic test. HNP-1 through HNP-3 localized in the junctional epithelium of clinically healthy gingiva and in the pocket epithelium of gingiva with periodontitis. When keratinocyte monolayers were incubated with neutrophil extracts, HNP-1 through HNP-3 were bound to the periphery of the growing cell colonies. In low HNP-1 concentrations, the keratinocyte proliferation enhanced. Moderate and high concentrations of HNP-1 increased the cellular death significantly. HNP-1 increased the attachment and spreading of keratinocytes on fibronectin-coated surfaces and bacterial attachment to keratinocytes in a concentration-dependent manner. HNP-1 plays a role in the integrity of keratinocytes by stimulating their proliferation, attachment, and spreading, whereas higher doses increase the bacterial attachment and keratinocyte death.

Effect of the sterilization method on the properties of Bombyx mori silk fibroin films

We have compared the effects of different sterilization techniques on the properties of Bombyx mori silk fibroin thin films with the view to subsequent use for corneal tissue engineering. The transparency, tensile properties, corneal epithelial cell attachment and degradation of the films were used to evaluate the suitability of certain sterilization techniques including gamma-irradiation (in air or nitrogen), steam treatment and immersion in aqueous ethanol. The investigations showed that gamma-irradiation, performed either in air or in a nitrogen atmosphere, did not significantly alter the properties of films. The films sterilized by gamma-irradiation or by immersion in ethanol had a transparency greater than 98% and tensile properties comparable to human cornea and amniotic membrane, the materials of choice in the reconstruction of ocular surface. Although steam-sterilization produced stronger, stiffer films, they were less transparent, and cell attachment was affected by the variable topography of these films. It was concluded that gamma-irradiation should be considered to be the most suitable method for the sterilization of silk fibroin films, however, the treatment with ethanol is also an acceptable method.

Tissue Factor Signals Airway Epithelial Basal Cell Survival via Coagulation and Protease-Activated Receptor Isoforms 1 and 2

Tissue factor (TF) initiates the extrinsic coagulation cascade and is a high-affinity receptor for coagulation factor VII. TF also participates in protease-activated receptor (PAR)1 and PAR2 activation. Human epithelial basal cells were previously purified on the basis of TF expression. The purpose of this study was to determine if tracheobronchial epithelial basal cell-associated TF drives coagulation and/or activates PARs to promote basal cell functions. We used human tracheobronchial tissues to isolate human airway epithelial cells using specific cell surface markers by flow cytometry and studied TF expression by immunostaining. TF-dependent fibrin network formation was observed by confocal and scanning electron microscopy. TF knockdown was done using short hairpin RNA, and TF mRNA was measured using quantitative RT-PCR. We found that 97 ± 5% of first-passage human tracheobronchial epithelial cells were basal cells, and 100% of these basal cells expressed TF. Basal cell-associated TF was active, but TF activity was dependent on added extrinsic coagulation cascade factors. TF inhibition caused basal cell apoptosis and necrosis. This was due to two parallel but interdependent TF-regulated processes: failure to generate a basal cell-associated fibrin network and suboptimal PAR1 and PAR2 activity. The data indicate that membrane surface TF mediates airway epithelial basal cell attachment, which maintains cell survival and mitotic potential. The implications of these findings are discussed in the context of basal cell-associated TF activity in normal and injured tissues and of the potential for repair of airway epithelium in lung disease.

Proliferative enteropathy in foals: Disease, diagnostics and transmission

Spermatozoa are known to bind to the epithelial cells lining the uterine tube in various species, but information in canids is conflicting and sparse. The first aim of this study was to measure the epithelial surface outline (ESO) of different regions of the canine uterine tube in the four stages of the oestrous cycle as an indicator of a changing potential reservoir for spermatozoa. The second aim was to identify the site of sperm storage in the bitch after natural mating. Reproductive tracts were collected from bitches undergoing routine ovariohysterectomy.Histological analysis showed that, when corrected for uterine tube size, the ESO of pro-oestrus (P < 0.005) and oestrus (P < 0.05) tubes were larger than anoestrus, but not metoestrus, tubes. The second study examined reproductive tracts from 12 Beagle bitches at 6, 12, 24 and 48 h after mating. Light and electron microscopy revealed large numbers of spermatozoa in the proximal regions of the uterus and particularly the distal utero-tubal junction (UTJ), with few present in the proximal UTJ or uterine tubes. Spermatozoa were bound by their heads to microvilli on the epithelial surface of the uterine lumen and to ciliated cells in the distal UTJ. This is the first report to measure and document differences in potential epithelial attachment sites of the uterine tubes at different stages of the oestrous cycle and to provide compelling evidence that the main spermatozoal storage site in the reproductive tract of the bitch is the distal UTJ.

Probiotics for optimal nutrition: from efficacy to guidelines.

Manipulation of the enteric microbiota with the goal of improving gut health is not a new strategy. This has been attempted through the use of antibiotics since the 1940s. However, despite identification of the first probiotic in 1917, progress in the therapeutic application of probiotics (health-promoting bacteria) has lagged behind consumer awareness and demand. Indeed, only in the past 5–10 y have scientists begun to understand the mechanisms of probiotic action and their associated applicability to specific disease conditions. This has opened up debate on the regulatory implications for probiotics and the subsequent commercialization of specific health claims, influenced by indications that factors sourced from certain probiotics may themselves be therapeutically useful. The 4 speakers discussed the targeted development of new probiotics and probiotic factors, the latest techniques to assess their efficacy, the expanding range of conditions with probiotic applicability, and the associated underlying changes in regulatory requirements. In the first presentation, Dr. Gordon Howarth summarized the known mechanisms of probiotic action described to date, which include competitive inhibition of epithelial attachment, modulation of the mucosal immune system,

Loss of dentin sialophosphoprotein leads to periodontal diseases in mice.

Dentin sialophosphoprotein (DSPP) and its cleaved products, dentin phosphoprotein (DPP) and dentin sialoprotein (DSP), play important roles in biomineralization. Recently, we observed that DSPP is highly expressed in the alveolar bone and cementum, indicating that this molecule may play an important role in the formation and maintenance of a healthy periodontium, and its deletion may cause increased susceptibility to periodontal diseases. The objective of this investigation was to study the effects of Dspp ablation on periodontal tissues by analyzing Dspp null mice. Newborn to 6-mo-old Dspp null mice were examined, and the 3- and 6-mo-old Dspp null mice were characterized in detail using X-ray radiography, histology and scanning electron microscopy (backscattered as well as resin-infiltrating). Wild-type mice of the same age groups served as the normal controls. The Dspp null mice showed significant loss of alveolar bone and cementum, particularly in the furcation and interproximal regions of the molars. The alveolar bone appeared porous while the quantity of cementum was reduced in the apical region. The canalicular systems and osteocytes in the alveolar bone were abnormal, with reduced numbers of canaliculi and altered osteocyte morphology. The loss of alveolar bone and cementum along with the detachment of the periodontal ligaments (PDL) led to the apical migration of the epithelial attachment and formation of periodontal pockets. Inactivation of DSPP leads to the loss of alveolar bone and cementum and increased susceptibility to bacterial infections in PDL of Dspp null mice. The fact that the loss of DSPP results in periodontal diseases indicates that this molecule plays a vital role in maintaining the health of the periodontium.

Kinetic and functional characterisation of the heparin‐binding peptides from human transglutaminase 2

Transglutaminase 2 (TG2) is an autoantigen in celiac disease (CD) and it has multiple biologic functions including involvement in cell adhesion through interactions with integrins, fibronectin (FN), and heparan sulfate proteoglycans. We aimed to delineate the heparin-binding regions of human TG2 by studying binding kinetics of the predicted heparin-binding peptides using surface plasmon resonance method. In addition, we characterized immunogenicity of the TG2 peptides and their effect on cell adhesion. The high-affinity binding of human TG2 to the immobilized heparin was observed, and two TG2 peptides, P1 (amino acids 202-215) and P2 (261-274), were found to bind heparin. The amino acid sequences corresponding to the heparin-binding peptides were located close to each other on the surface of the TG2 molecule as part of the α-helical structures. The heparin-binding peptides displayed increased immunoreactivity against serum IgA of CD patients compared with other TG2 peptides. The cell adhesion reducing effect of the peptide P2 was revealed in Caco-2 intestinal epithelial cell attachment to the FN and FN-TG2 coated surfaces. We propose that TG2 amino acid sequences 202-215 and 261-274 could be involved in binding of TG2 to cell surface heparan sulfates. High immunoreactivity of the corresponding heparin-binding peptides of TG2 with CD patient's IgA supports the previously described role of anti-TG2 autoantibodies interfering with this interaction.

Glycodelin suppresses endometrial cell migration and invasion but stimulates spheroid attachment

Glycodelin contains four isoforms with diverse biological functions. Glycodelin-A is potentially a diagnostic marker for cancer patients and receptivity marker of the secretory endometrium. Yet, direct evidence for the role of glycodelin in the regulation of endometrial epithelial cell migration, invasion and attachment of trophoblastic spheroids (blastocyst surrogate) is lacking. In this study, the human glycodelin gene was stably transfected into human endometrial (HEC1-B) cells. Forced expression of glycodelin in HEC1-B cells did not affect cell proliferation, cell viability or cell-cycle progression, but significantly reduced migration and invasion of the stably transfected cells (both P<0.05). The migration rate returned to normal levels when the glycodelin-forced-expressing HEC1-B cells were treated with glycodelin RNAi. Furthermore, forced expression of glycodelin in HEC1-B cells significantly increased the attachment of trophoblastic spheroids onto the endometrial epithelial cells (P<0.05). In summary, glycodelin suppressed endometrial cell migration and invasion but enhanced spheroid attachment.Glycodelin contains four similar forms with different biological functions. Glycodelin-A is a potential diagnostic marker for cancer patients and receptivity marker of the uterus. Yet, direct evidence for the role of glycodelin on the regulation of uterine epithelial cell migration, invasion and attachment of trophoblastic spheroids (embryo surrogate) is lacking. In this study, the human glycodelin gene was stably expressed in the human endometrial (HEC1-B) cells. Forced expression of glycodelin in HEC1-B cells did not affect cell proliferation, cell viability or cell-cycle progression, but significantly reduced migration and invasion of the stably expressed cells. The migration rate returned to normal levels when the glycodelin-forced-expressing HEC1-B cells were treated with glycodelin RNAi. Furthermore, forced expression of glycodelin in HEC1-B cells significantly increased the attachment of trophoblastic spheroids onto the endometrial epithelial cells. In summary, glycodelin has dual roles on cell migration/invasion and may be involved in embryo attachment.

Nanoscale E-Cadherin Ligand Patterns Show Threshold Size for Cellular Adhesion and Adherence Junction Formation

The role of ligand spatial distribution on the formation of cadherin mediated cell-cell contacts is studied utilizing nanopatterns of E-cadherin ligands. Protein patches ranging in size from 100 to 800 nm prepared by colloidal lithography critically influence adhesion, spreading, and formation of adherence junctions in epithelial cells. Cells at 100 nm patterns show poor adhesion, while larger pattern sizes show good adhesion, significant spreading, and defined cortical actin. We estimate a threshold of 0.03 μm(2) for epithelial cellular attachment via E-Cadherin.

Synthesis, characterization and ocular biocompatibility of potential keratoprosthetic hydrogels based on photopolymerized poly(2-hydroxyethyl methacrylate)-co-poly(acrylic acid)

Development of functional hydrogels for use in anterior lamellar keratoplasty can potentially eliminate the risk of corneal endothelial rejection associated with penetrating keratoplasty. This study aims to copolymerize 2-hydroxyethyl methacrylate (HEMA) with acrylic acid (AAc) to fabricate a transparent, bioinert keratoprosthesis base material that evokes minimal ocular cell/tissue response and suppresses corneal epithelial cell attachment and growth. In the presence of varying amounts of monomers (i.e., 72–92% HEMA and 0–20% AAc), initiators (i.e., 2–6% 2,2-diethoxyacetophenone (DEAP)), and cross-linkers (i.e., 2–6% trimethylolpropane trimethacrylate (TMPTMA)), the photopolymerized samples were synthesized successfully by varying reaction time (i.e., 10–50 min), and were characterized by Fourier transform infrared spectroscopy and contact angle measurements. While the introduction of PAAc into the structure of PHEMA can enhance the water content and oxygen and nutrient permeability, it simultaneously reduces mechanical and suture strength as well as resists protein adsorption and cell adhesion. For an incomplete cross-linked hydrogel prepared with lowest DEAP and TMPTMA content or least UV irradiation time, significant cytotoxicity and inflammation were noted, probably due to the presence of more unreacted CC bonds. The in vitro and in vivo studies showed that the membranes obtained from optimized photopolymerization conditions had good compatibility with the corneal epithelial cell cultures and the anterior segment of the eye. Additionally, the properties of this poly(HEMA-co-AAc) material were comparable to those of native corneas, suggesting that it may be a promising candidate for direct application in artificial cornea or further surface functionalization during keratoprosthesis design.

Initial attachment of human oral keratinocytes cultured on zirconia or titanium

Initial attachment of human oral keratinocytes (HOKs) cultured on mirror-surfaced commercially pure titanium (Ti) or yttria-stabilized tetragonal zirconia polycrystals (TZP) was investigated. Numbers of viable attached HOKs, their mRNAs and proteins expression of laminin γ2 and integrin β4 were evaluated using the WST-1 assay, quantitative real-time PCR and enzyme-linked immunosorbent assay, respectively. Localization of laminin γ2 and integrin β4 was observed using immunofluorescent staining. Cell spreading was evaluated by measuring the perimeter of actin on fluorescent stained images, and cell morphology was examined using scanning electron microscopy. At 1 h TZP elicited less of initial attachment than Ti in terms of mRNAs expression and proteins expression of laminin γ2 and integrin β4 (p<0.05). However, at 48 h TZP was showed similar initial attachment in comparison to Ti. Therefore, it was suggested that TZP has a potential to form epithelial attachment like Ti.

Time-dependent effects of low-temperature atmospheric-pressure argon plasma on epithelial cell attachment, viability and tight junction formation in vitro

The application of physical plasma to living tissues is expected to promote wound healing by plasma disinfection and stimulation of tissue regeneration. However, the effects of plasma on healthy cells must be studied and understood. In our experiments we used an argon plasma jet (kINPen®09) to gain insights into time-dependent plasma effects on cell attachment, viability and tight junction formation in vitro. Murine epithelial cells mHepR1 were suspended in complete cell culture medium and were irradiated with argon plasma (direct approach) for 30, 60 and 120 s. Suspecting that physical plasma may exert its effect via the medium, cell culture medium alone was first treated with argon plasma (indirect approach) and immediately afterwards, cells were added and also cultured for 24 h. Cell morphology and vitality were verified using light microscopy and an enzyme-linked immunosorbent assay. Already after 30 s of treatment the mHepR1 cells lost their capability to adhere and the cell vitality decreased with increasing treatment time. Interestingly, the same inhibitory effect was observed in the indirect approach. Furthermore, the argon plasma-treated culture medium-induced large openings of the cell's tight junctions, were verified by the zonula occludens protein ZO-1, which we observed for the first time in confluently grown epithelial cells.

Prosthodontic treatment of a patient taking nitrogen-containing bisphosphonates to preserve the integrity of the epithelial attachment: A clinical report

Osteonecrosis of the jaw has been identified in recent years as an unfortunate potential side effect for patients taking nitrogen-containing bisphosphonates. Many authors have attempted unsuccessfully to elucidate the mechanism behind this drug-induced malady, leaving dentists with unclear guidelines on how to treat these patients. Recent literature suggests a threshold-related impairment of epithelial cell migration over bone. A conservative, non-invasive approach aimed at preserving the epithelial attachment in a patient on a long-term oral alendronate protocol is described. The advantage of this approach is to prevent a highly destructive bone degenerative process that does not have a clear and predictable treatment protocol.

Short-term vs long-term calcium hydroxide therapy after immediate tooth replantation: a histomorphometric study in monkey’s teeth

Endodontic treatment is an important step of tooth replantation protocols, but the ideal moment for definitive obturation of replanted teeth has not yet been established. In this study, a histomorphometric analysis was undertaken to evaluate the repair process on immediate replantation of monkey's teeth after calcium hydroxide (CH) therapy for 1 and 6 months followed by root canal filling with a CH-based sealer (Sealapex(®) ). The maxillary and mandibular lateral incisors of five female Cebus apella monkeys were extracted, kept in sterile saline for 15 min, replanted and splinted with stainless steel orthodontic wire and composite resin for 10 days. In Group I (control), definitive root canal filling was performed before tooth extraction. In Groups II and III, CH therapy started after removal of splint, and definitive root canal filling was performed 1 and 6 months later, respectively. The animals were euthanized 9 months after replantation, and specimens were processed for histomorphometric analysis. In all groups, epithelial attachment occurred at the cementoenamel junction or very close to this region; the areas of resorption on root surface had small extension and depth and were repaired by newly formed cementum; and the periodontal ligament was organized. Statistical analysis of the scores obtained for the histomorphometric parameters did not show any statistically significant difference (P = 0.1221) among the groups. The results suggests that when endodontic treatment is initiated 10 days after immediate replantation and an antibiotic regimen is associated, definitive root canal filling can be performed after a short-term CH therapy.

C. elegans model of neuronal aging

Aging of the nervous system underlies the behavioral and cognitive decline associated with senescence. Understanding the molecular and cellular basis of neuronal aging will therefore contribute to the development of effective treatments for aging and age-associated neurodegenerative disorders. Despite this pressing need, there are surprisingly few animal models that aim at recapitulating neuronal aging in a physiological context. We recently developed a C. elegans model of neuronal aging, and showed that age-dependent neuronal defects are regulated by insulin signaling. We identified electrical activity and epithelial attachment as two critical factors in the maintenance of structural integrity of C. elegans touch receptor neurons. These findings open a new avenue for elucidating the molecular mechanisms that maintain neuronal structures during the course of aging.

Ultrastructural analysis of implant–soft tissue interface on a three dimensional tissue‐engineered oral mucosal model

A three dimensional tissue-engineered human oral mucosal model (3D OMM) used in the investigation of implant-soft tissue interface was recently reported. The aim of this study was to examine the ultrastructural features of soft tissue attachment to various titanium (Ti) implant surfaces based on the 3D OMM. Two techniques, that is, focus ion beam (FIB) and electropolishing techniques were used to prepare specimens for transmission electron microscopic (TEM) analysis of the interface. The 3D OM consisting of both epithelial and connective tissue layers was constructed by co-culturing human oral keratinocytes and fibroblasts onto an acellular dermis scaffold. Four types of Ti surface topographies were tested: polished, machined (turned), sandblasted, and TiUnite. The specimens were then processed for TEM examination using FIB (Ti remained) and electropolishing (Ti removed) techniques. The FIB sections showed some artifact and lack of details of ultrastructural features. In contrast, the ultrathin sections prepared from the electropolishing technique showed a residual Ti oxide layer, which preserved the details for intact ultrastructural interface analysis. There was evidence of hemidesmosome-like structures at the interface on the four types of Ti surfaces, which suggests that the tissue-engineered oral mucosa formed epithelial attachments on the Ti surfaces.

Expression and activity of metalloproteinases in the digital laminae of horses with starch gruel-induced laminitis

Expression and activity of metalloproteinases in the digital laminae of horses with starch gruel-induced laminitis

The effect of cryopreservation on the capacitation status and epithelial cell attachment capability of dog spermatozoa

Freezing and cooling of spermatozoa during cryopreservation for artificial insemination causes ultrastructural changes in the acrosome and plasma membrane which reduces longevity and fertility. Cryopreservation-induced capacitation-like changes and reduced ability of spermatozoa to bind to the cells of the reproductive tract of the bitch may contribute to the reduced fertility of cryopreserved spermatozoa. Previous studies in the dog have investigated the effects of extending and cooling spermatozoa on the plasma membrane but often only after freeze-thawing and not in conjunction with an assessment of their ability to bind to uterine tube epithelial explants. This study investigated the effect of each stage of the cryopreservation process on capacitation and attachment to the reproductive tract of the bitch. The capacitation status of spermatozoa was studied over time after cryopreservation using a chlortetracycline and Hoechst 33258 stain. The ability of spermatozoa to bind to uterine tube epithelial explants was studied using Hoechst 33342 stain. Extending, cooling and freeze-thawing promoted capacitation and decreased the spermatozoal binding ability. The effect of each stage appeared to be cumulative with the freeze-thawing stage being the most dramatic. The results suggested that the cumulative effect of each stage of the cryopreservation process results in the promotion of capacitation before spermatozoa have reached the site of fertilisation, and therefore spermatozoa have reduced ability to attach to epithelial cells. These effects are contributory factors to the reduced fertility of cryopreserved spermatozoa.

Autoantibodies from patients with celiac disease inhibit transglutaminase 2 binding to heparin/heparan sulfate and interfere with intestinal epithelial cell adhesion

Autoantibodies from patients with celiac disease (CD) can influence transglutaminase 2 (TG2) activity and its cellular functions, but the exact mechanisms have remained unknown. Our objective was to study whether autoantibodies could modulate TG2 binding to heparin/heparan sulfate (HS) and intestinal epithelial cell attachment to fibronectin-TG2 matrix. Anti-TG2 antibodies were purified by TG2 affinity chromatography from sera of patients with active CD. Serum and antibody effects on TG2 binding to heparin/HS, on transamidase activity of TG2, as well as on Caco-2 cell attachment to fibronectin-TG2 matrix were assessed using microplate assays. Both sera and purified anti-TG2 antibodies from CD patients with high anti-TG2 IgA levels reduced TG2 binding to heparin/HS as compared with those with low anti-TG2 IgA or controls. There was a negative correlation between anti-TG2 IgA levels and TG2 binding to heparin/HS. Treatment of fibronectin-TG2 coated wells with CD patients' sera or purified anti-TG2 antibodies reduced attachment of Caco-2 cells onto the plate as compared with the control samples. The effect of CD patients' antibodies on Caco-2 cell attachment to fibronectin-TG2 matrix occurred independently of the inhibition of cell adhesion by Arg-Gly-Asp sequence containing peptides. Anti-TG2 autoantibodies had no effect on transamidase activity of TG2 in vitro. We suggest that modulation of adhesion function of TG2 by autoantibodies from patients with CD could be related to the inhibition of TG2 binding to HS residues of cell surface proteoglycans and could have possible implications for CD pathogenesis.

Ligation of CD24 expressed by oral epithelial cells induces kinase dependent decrease in paracellular permeability mediated by tight junction proteins

In previous studies we demonstrated uniform strong expression of CD24 in the epithelial attachment to the tooth and in the migrating epithelium of the periodontitis lesion. Titers of serum antibodies auto-reactive with CD24 peptide correlated with reduced severity of periodontal disease. In the present study an epithelial culture model with close correspondence for expression patterns for tight junction components in periodontal epithelia was used. Ligation of CD24 expressed by oral epithelial cells with an anti-CD24 antibody induced formation of tight junctions and live-cell imaging confirmed that paracellular diffusion of fluorochrome-labeled dextran was reduced. Expression of mRNA and protein for zona occludens-1, -2, junction adhesion molecule-A (JAM-A), occludin and claudins-1, -4, -8, -15, -18 was significantly increased following ligation of CD24 but only claudins-4 and -15, JAM-A, occludin and zona occludens-1 and -2 were increased at cell contacts. This change in expression patterns reflected that observed between the epithelium of the periodontal lesion and that of the healthy gingival attachment. In the model system, response profiles to kinase inhibitors indicated a key role of c-Src kinase activation in the development of diffusion-limiting tight junction complexes. Activation was confirmed by demonstrating concomitant phosphorylation of the kinase. Pre-incubation with antibodies against JAM-A and claudin-15 prevented barrier-enhancing effects of anti-CD24 antibodies while pre-incubation with antibody to claudin-4 was partially effective. It is concluded that antibodies to CD24 facilitate expression and location of JAM-A, claudins-4 and -15 that mediate enhanced epithelial barrier function in a protective response against bacterial products.