Epithelium Of Gastrointestinal Tract Research Articles

The Multiple Roles of Heat Shock Proteins in the Development of Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD), a chronic inflammatory condition of the human intestine, comprises Crohn's Disease (CD) and Ulcerative Colitis (UC). IBD causes severe gastrointestinal symptoms and increases the risk of developing colorectal carcinoma. Although the etiology of IBD remains ambiguous, complex interactions between genetic predisposition, microbiota, epithelial barrier, and immune factors have been implicated. The disruption of intestinal homeostasis is a cardinal characteristic of IBD. Patients with IBD exhibit intestinal microbiota dysbiosis, impaired epithelial tight junctions, and immune dysregulation; however, the relationship between them is not completely understood. As the largest body surface is exposed to the external environment, the gastrointestinal tract epithelium is continuously subjected to environmental and endogenous stressors that can disrupt cellular homeostasis and survival. Heat shock proteins (HSPs) are endogenous factors that play crucial roles in various physiological processes, such as maintaining intestinal homeostasis and influencing IBD progression. Specifically, HSPs share an intricate association with microbes, intestinal epithelium, and the immune system. In this review, we aim to elucidate the impact of HSPs on IBD development by examining their involvement in the interactions between the intestinal microbiota, epithelial barrier, and immune system. The recent clinical and animal models and cellular research delineating the relationship between HSPs and IBD are summarized. Additionally, new perspectives on IBD treatment approaches have been proposed.

C-Jun N-terminal Kinase (JNK), p38, and Caspases: Promising Therapeutic Targets for the Regulation of Apoptosis in Cancer Cells by Phytochemicals

Abstract: Carcinogenesis is a process in which uncontrolled cell proliferation forms preneoplastic nodules which precede the appearance of cancer. In normal cells, growth and proliferation are regulated by certain growth and hormonal stimulation, while mutational alterations in these signals render the cells independent and resistant to these signals. In cancer, the critical homeostatic balance between cell growth and apoptosis is lost and the cells continue to survive beyond their normal life span. The activation of c-Jun N-terminal kinase (JNK), p38 and caspases are involved in potential proapoptotic signaling pathways. JNK, p38 MAPK pathway and caspases play a crucial role in the control of apoptosis in response to stress. The most recent and up-to-date literature was evaluated in this study, which describes the role of JNK, p38 MAPK pathway and caspases as therapeutic target in cancer. Chemotherapy uses drugs that are cytotoxic to highly proliferating tumor cells but also kills the non-tumor rapidly proliferating cells in the hair, skin and gastrointestinal tract epithelium, thereby accounting the side effects of these types of treatments. Recently, chemopreventive modalities derived from phytoconstituents present in plants provide a broad-spectrum strategy to overcome the incidence of cancer. Non-toxic, safe and affordable bioavailabilities of chemopreventive agents provide credence support in the field of cancer research compared to conventional therapies that cause serious consequences. Chemoprevention envisages the basic mechanisms like modulating the activity of xenobiotic-metabolizing enzymes, induction of apoptosis, immune system activation, suppressing angiogenesis and the formation of metastasis, antioxidant and anti-inflammatory properties. The present review highlighted the role of phytoconstituents derived from food, vegetables and medicinal plants in the induction of apoptosis in cancer cells, which in turn is mediated by the activation of JNK, p38 MAPK pathways, and caspases.

Altered Expression of Antimicrobial Peptides in the Upper Gastrointestinal Tract of Patients with Diabetes Mellitus.

Antimicrobial peptides (AMP) are essential components of innate immunity with a broad range of antimicrobial activities against bacteria, viruses, and fungi. The aim of this study was to investigate AMP expression in the upper gastrointestinal tract in normal and pathological metabolic states in humans. Furthermore, we examined the correlation between vitamin D levels and AMP expression in the same cohort. Serum concentrations of 25-hydroxyvitamin D3 were measured, and mRNA expression of β-defensins HBD-1, -2, -3, -4, α-defensins HD-5 and -6 and cathelicidin in the upper gastrointestinal tract epithelia were determined by quantitative RT-PCR in 31 individuals (10 with type 2 diabetes, 10 with insulin resistance, and 11 healthy controls). The majority of the cohort showed low vitamin D concentrations, which were negatively correlated with mRNA expression levels of HBD-3 in corpus mucosa. HBD-1 and HBD-3 mRNA were expressed in corpus mucosa, with the former significantly decreased in patients with diabetes. Hence, we conclude that type 2 diabetes is associated with reduced AMP expression in the upper gastrointestinal tract, which might contribute towards epithelial barrier dysfunction and increased bacterial translocation in these patients.

P251 Level of Interleukin-17 in Inflammatory Bowel Disease and Its relation to disease activity.

Abstract Background Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disorder of the gastrointestinal tract (GIT).It causes progressive structural and functional damage to the GIT epithelium. Chronic inflammation in IBD is characterized by an imbalance in the production of T helper -1 (Th1),Th2 andTh17 cytokines.This imbalance is important in chronic inflammatory process, since the formation of defective immune response to pathogenic agents promotes the recurrence of the disease.Whether interleukin-17A (IL-17A) has pathogenic and/or protective roles in the gut mucosa is controversial.The aim of this study was to detect serum IL-17 levels in IBD patients and its relation to disease activity. Methods This was a single center cross-sectional study, conducted at hepatology & gastroenterology unit, Mansoura specialized Medical Hospital, Egypt.Patients who were aged 18-65 years and diagnosed either UC or CD based on previous colonoscopy were included.55 patients were UC, 24 patients were CD,21 patients were control.Patients who were excluded were <15 y, with history of GIT malignancy or any comorbidities affecting kidney,liver ,etc.All population were subjected to routine history, physical examination& laboratory investigations including serum IL-17 by ELISA besides CBC,CRP,ESR,Stool analysis, fecal calprotectin. Results Table (1): Correlation between laboratory findings and IL-17 among studied cases We found that serum IL-17 level was increased significantly among UC ;median (min-max)= 72(21-502), in CD 54.5(25-260) versus control19(14-35) ng/l, P<0.001.However, it was not correlated to the disease activity either Mayo score of UC or CDAI of CD. It showed significant correlation to the extent of inflammation in UC affecting the colon (either proctosigmoiditis or left sided colitis or pan colitis), also to the type of CD (either inflammatory or stricturing or fistulizing) by P<0.05. It was not correlated significantly with any of the IBD activity markers (either CRP, ESR,or fecal calprotectin).Yet there was only negative significant correlation with Hb level (r =-0.28, p=0.005). AUC was significantly differentiating between IBD and control group =0.993 with the best-detected cut off point from curve is 32 yielding sensitivity of 97.5% and specificity of 95.2%, while for discriminating activity of IBD by IL-17 ;AUC of UC and CD =0.56 & 0.65, with sensitivity 52.6% & 61.5% and specificity 58.3% &63.6 % respectively. Conclusion IL-17 increases in colonic inflammation significantly more than in control group, however its increase is not correlated to IBD activity.

Do extreme postprandial levels of oxygen, carbon dioxide, and ammonia in the digestive tract equilibrate with the bloodstream in the freshwater rainbow trout (Oncorhynchus mykiss)?

The gastrointestinal tract (GIT) lumen of teleosts harbors extreme conditions, especially after feeding: high PCO2 (20-115Torr), total ammonia (415-3710μM), PNH3 (79-1760μTorr in the intestine), and virtual anoxia (PO2 < 1Torr). These levels could be dangerous if they were to equilibrate with the bloodstream. Thus, we investigated the potential equilibration of O2, CO2, and ammonia across the GIT epithelia in freshwater rainbow trout by monitoring postprandial arterial and venous blood gases in vivo and in situ. In vivo blood was sampled from the indwelling catheters in the dorsal aorta (DA) and subintestinal vein (SIV) draining the posterior intestine in the fasting state and at 4 to 48h following catheter-feeding. To investigate possible ammonia absorption in the anterior part of the GIT, blood was sampled from the DA, SIV and hepatic portal vein (HPV) from anaesthetized fish in situ following voluntary feeding. We found minimal equilibration of all three gases between the GIT lumen and the SIV blood, with the latter maintaining pre-feeding levels (PO2 = 25-49Torr, PCO2 = 6-8Torr, and total ammonia = 117-134μM and PNH3 = 13-30μTorr at 48h post-feeding). In contrast to the SIV, we found that the HPV total ammonia more than doubled 24h after feeding (128 to 297μM), indicative of absorption in the anterior GIT. Overall, the GIT epithelia of trout, although specialized for absorption, prevent dangerous levels of PO2, PCO2 and ammonia from equilibrating with the blood circulation.

Ammonia transport is independent of PNH3 gradients across the gastrointestinal epithelia of the rainbow trout: A role for the stomach.

Although the gastrointestinal tract (GIT) is an important site for nitrogen metabolism in teleosts, the mechanisms of ammonia absorption and transport remain to be elucidated. Both protein catabolism in the lumen and the metabolism of the GIT tissues produce ammonia which, in part, enters the portal blood through the anterior region of the GIT. The present study examined the possible roles of different GIT sections of rainbow trout (Oncorhynchus mykiss) in transporting ammonia in its unionized gas form-NH3 -by changing the PNH3 gradient across GIT epithelia using in vitro gut sac preparations. We also surveyed messengerRNA expression patterns of three of the identified Rh proteins (Rhbg, Rhcg1, and Rhcg2) as potential NH3 transporters and NKCC as a potential ammonium ion (NH4 + ) transporter along the GIT of rainbow trout. We found that ammonia absorption is not dependent on the PNH3 gradient despite expression of Rhbg and Rhcg2 in the intestinal tissues, and Rhcg2 in the stomach. We detected no expression of Rhbg in the stomach and no expression of Rhcg1 in any GIT tissues. There was also a lack of correlation between ammonia transport and [NH4 + ] gradient despite NKCC expression in all GIT tissues. Regardless of PNH3 gradients, the stomach showed the greatest absorption and net tissue consumption of ammonia. Overall, our findings suggest nitrogen metabolism zonation of GIT, with stomach serving as an important site for the absorption, handling and transport of ammonia that is independent of the PNH3 gradient.

Exploring the translocation behaviours in vivo of herpetrione amorphous nanoparticles via oral delivery

Nanotechnology has been a primary strategy to enhance oral bioavailability of poorly water soluble drugs. However, the limited information in vivo fate of impedes the development of nanoparticles via the oral delivery, especially the amorphous nanoparticles with high energy states are rarely reported. This study is to track the translocation of oral herpetrione amorphous nanoparticles (HPE-ANPs). We prepare amorphous particles (ANPs) of various sizes (200 nm and 450 nm), which are embedded with an aggregation-caused quenching (ACQ) dyes for tracking the intact nanoparticles. Nanoparticles remain in the gastrointestinal tract (GIT) for 8 h following oral administration, suggesting that most ANPs was mainly degraded or absorbed in the small intestine. Ex vivo imaging shows that the fluorescent signals are observed in the GIT and liver but not in other organs, which attributed to low absorption of integral nanoparticles. Besides, HPE-ANPs may be directly interact with GIT epithelia, and ileum provides better absorption than the jejunum. Cellular studies prove that integral HPE-ANPs can be taken up by enterocyte, while it penetrates cell monolayers only small amounts. In conclusion, we speculate that the drug in the form of integral nanoparticles and small molecules may be co-absorbed to improve bioavailability in vivo.

Gut and Gill-Associated Microbiota of the Flatfish European Plaice (Pleuronectes platessa): Diversity, Metabolome and Bioactivity against Human and Aquaculture Pathogens.

Similar to other marine holobionts, fish are colonized by complex microbial communities that promote their health and growth. Fish-associated microbiota is emerging as a promising source of bioactive metabolites. Pleuronectes platessa (European plaice, plaice), a flatfish with commercial importance, is common in the Baltic Sea. Here we used a culture-dependent survey followed by molecular identification to identify microbiota associated with the gills and the gastrointestinal tract (GIT) of P. platessa, then profiled their antimicrobial activity and metabolome. Altogether, 66 strains (59 bacteria and 7 fungi) were isolated, with Proteobacteria being the most abundant phylum. Gill-associated microbiota accounted for higher number of isolates and was dominated by the Proteobacteria (family Moraxellaceae) and Actinobacteria (family Nocardiaceae), whereas Gram-negative bacterial families Vibrionaceae and Shewanellaceae represented the largest group associated with the GIT. The EtOAc extracts of the solid and liquid media cultures of 21 bacteria and 2 fungi representing the diversity of cultivable plaice-associated microbiota was profiled for their antimicrobial activity against three fish pathogens, human bacterial pathogen panel (ESKAPE) and two human fungal pathogens. More than half of all tested microorganisms, particularly those originating from the GIT epithelium, exhibited antagonistic effect against fish pathogens (Lactococcus garvieae, Vibrio ichthyoenteri) and/or human pathogens (Enterococcus faecium, methicillin-resistant Staphylococcus aureus). Proteobacteria represented the most active isolates. Notably, the solid media extracts displayed higher activity against fish pathogens, while liquid culture extracts were more active against human pathogens. Untargeted metabolomics approach using feature-based molecular networking showed the high chemical diversity of the liquid extracts that contained undescribed clusters. This study highlights plaice-associated microbiota as a potential source of antimicrobials for the control of human and the aquaculture-associated infections. This is the first study reporting diversity, bioactivity and chemical profile of culture-dependent microbiota of plaice.

An updated review on food-derived bioactive peptides: Focus on the regulatory requirements, safety, and bioavailability.

Food-derived bioactive peptides (BAPs) are recently utilized as functional food raw materials owing to their potential health benefits. Although there is a huge amount of scientific research about BAPs' identification, purification, characterization, and physiological functions, and subsequently, many BAPs have been marketed, there is a paucity of review on the regulatory requirements, bioavailability, and safety of BAPs. Thus, this review focuses on the toxic peptides that could arise from their primary proteins throughout protein extraction, protein pretreatment, and BAPs' formulation. Also, the influences of BAPs' length and administration dosage on safety are summarized. Lastly, the challenges and possibilities in BAPs' bioavailability and regulatory requirements in different countries were also presented. Results revealed that the human studies of BAPs are essential for approvals as healthy food and to prevent the consumers from misinformation and false promises. The BAPs that escape the gastrointestinal tract epithelium and move to the stomach are considered good peptides and get circulated into the blood using different pathways. In addition, the hydrophobicity, net charge, molecular size, length, amino acids composition/sequences, and structural characteristics of BAPs are critical for bioavailability, and appropriate food-grade carriers can enhance it. The abovementioned features are also vital to optimize the solubility, water holding capacity, emulsifying ability, and foaming property of BAPs in food products. In the case of safety, the possible allergenic and toxic peptides often exhibit physiological functions and could be produced during the hydrolysis of food proteins. It was also noted that the production of iso-peptides bonds and undesirable Maillard reaction might occur during protein extraction, sample pretreatments, and peptide synthesis.

Insights into the cellular pharmacokinetics and pharmacodynamics of thiopurine antimetabolites in a model of human intestinal cells

Thiopurines, immunomodulating drugs used in the management of different chronic autoimmune conditions and as anti-leukemic agents, may exert in some cases gastrointestinal toxicity. Moreover, since these agents are administered orally, they are absorbed across the gastrointestinal tract epithelium. On these premises, cellular and molecular events occurring in intestinal cells may be important to understand thiopurine effects. However, quantitative information on the biotransformation of thiopurines in intestinal tissues is still limited. To shed light on biotransformation processes specific of the intestinal tissue, in this study thiopurine metabolites concentrations were analyzed by an in vitro model of human healthy colon, the HCEC cell line, upon exposure to cytotoxic concentrations of azathioprine or mercaptopurine; the investigation was carried out using an innovative mass spectrometry method, that allowed the simultaneous quantification of 11 mono-, di-, and triphosphate thionucleotides. Among the 11 metabolites evaluated, TIMP, TGMP, TGDP, TGTP, MeTIMP, MeTIDP and MeTITP were detectable in HCEC cells treated with azathioprine or mercaptopurine, considering two different incubation times before the addition of the drugs (4 and 48 h). Different associations between metabolites concentrations and cytotoxicity were detected. In particular, the cytotoxicity was dependent on the TGMP, TGDP, TGTP and MeTITP concentrations after the 4 h incubation before the addition of thiopurines. This may be an indication that, to study the association between thiopurine metabolite concentrations and the cytotoxicity activity in vitro, short growth times before treatment should be used. Moreover, for the first time our findings highlight the strong correlation between cytotoxicity and thiopurine pharmacokinetics in HCEC intestinal cells in vitro suggesting that these cells could be a suitable in vitro model for studying thiopurine intestinal cytotoxicity.

Gut in COVID 19-is it worth noticing.

Although much has been talked and written about the respiratory menace that Coronavirus disease causes, a close examination reveals that gut symptoms are equally important diagnostic markers for COVID-19. Almost 53% of COVID-19 patients experience gastrointestinal (GI) symptoms. The entry of the SARS Cov-2 virus is mediated through angiotensin-converting enzyme receptors which are abundant in the GI tract. The virus also affects the GI tract through the gut lung axis. In addition to the GI tract epithelium, hepatobiliary and pancreatic systems are also affected in COVID through multiple mechanisms. GI manifestations vary from relatively benign symptoms such as nausea vomiting diarrhea to rare cases of life-threatening mesenteric vein thrombosis. The relationship of the symptoms with morbidity and mortality is not clear. Anorexia is related to inflammation, and agneusia and anosmia carry a good prognosis. Psychiatric manifestations may be more common in those with GI affection, inflammation being the common pathogenic factor. Treatment is symptomatic, and proper hygiene precautions are necessary considering the possible fecal shedding of the virus, especially during endoscopic procedures on the GI tract.

Benefits of bacteria-derived exopolysaccharides on gastrointestinal microbiota, immunity and health

The gastrointestinal tract (GIT) is colonized by a broad spectrum of microorganism, of which bacteria are especially recognized for the health effects they exert. However insight in the effector molecules on the bacteria responsible are still largely lacking. Recently, bacterial exopolysaccharides (EPS), which are glycan structures on the bacterial cell wall, have gained considerable attention for their effects on human health. EPS are found to act as polymers that directly influence bacterial interactions with their host, such as bacterial adhesion to the GIT epithelium, their influence on immune responses, and the intestinal microbiota. These effects are highly dependent on the type of EPS structures and might be related to specific monosaccharides or linkages in EPS. Here, current knowledge on structure-specific EPS functions is reviewed in view of possible use of EPS to stimulate intestinal health and the formulation of dietary EPS mixtures or the possible creation of new EPS structures.

Small Bowel Adenocarcinomas Featuring Special AT-Rich Sequence-Binding Protein 2 (SATB2) Expression and a Colorectal Cancer-Like Immunophenotype: A Potential Diagnostic Pitfall.

Simple SummarySince small bowel adenocarcinoma may mimic a colorectal primary neoplasm histologically, it is pivotal to find biomarkers to discriminate these two biologically distinct neoplasms. The aim of our study was to evaluate the expression of special AT-rich sequence-binding protein 2 (SATB2), expressed in the vast majority of colorectal carcinomas, and other gastrointestinal phenotypic markers, such as cytokeratin 7, cytokeratin 20 and caudal type homeobox 2 (CDX2), in 100 small bowel adenocarcinomas. We identified 20 SATB2-positive small bowel adenocarcinomas, including nine sporadic cancers, seven celiac disease-associated cancers and four Crohn’s disease-associated small bowel adenocarcinomas. Six small bowel adenocarcinomas, including two cases associated with celiac disease and four sporadic, displayed a full colorectal carcinoma-like immunoprofile. Unlike SATB2, cytokeratin patterns stratified small bowel adenocarcinoma patient prognosis. The small bowel should be considered as one of the possible sites of origin in cancers of unknown primary, even when the neoplasm shows a colorectal carcinoma-like immunoprofile.Special AT-rich sequence-binding protein 2 (SATB2) is a transcription factor expressed by colonic cryptic epithelium and epithelial neoplasms of the lower gastrointestinal (GI) tract, as well as by small bowel adenocarcinomas (SBAs), though at a lower rate. Nevertheless, up to now, only small SBA series, often including a very limited number of Crohn’s disease-associated SBAs (CrD-SBAs) and celiac disease-associated SBAs (CD-SBA), have been investigated for SATB2 expression. We evaluated the expression of SATB2 and other GI phenotypic markers (cytokeratin (CK) 7 and CK20, caudal type homeobox 2 (CDX2) and alpha-methylacyl-CoA racemase (AMACR)), as well as mismatch repair (MMR) proteins, in 100 SBAs, encompassing 34 CrD-SBAs, 28 CD-SBAs and 38 sporadic cases (Spo-SBAs). Any mutual association and correlation with other clinico-pathologic features, including patient prognosis, were searched. Twenty (20%) SATB2-positive SBAs (4 CrD-SBAs, 7 CD-SBAs and 9 Spo-SBAs) were identified. The prevalence of SATB2 positivity was lower in CrD-SBA (12%) in comparison with both CD-SBAs (25%) and Spo-SBAs (24%). Interestingly, six SBAs (two CD-SBAs and four Spo-SBAs) displayed a full colorectal carcinoma (CRC)-like immunoprofile (CK7−/CK20+/CDX2+/AMACR+/SATB2+); none of them was a CrD-SBA. No association between SATB2 expression and MMR status was observed. Although SATB2-positive SBA patients showed a more favorable outcome in comparison with SATB2-negative ones, the difference did not reach statistical significance. When cancers were stratified according to CK7/CK20 expression patterns, we found that CK7−/CK20- SBAs were enriched with MMR-deficient cases (71%) and patients with CK7−/CK20− or CK7−/CK20+ SBAs had a significantly better survival rate compared to those with CK7+/CK20− or CK7+/CK20+ cancers (p = 0.002). To conclude, we identified a small (6%) subset of SBAs featuring a full CRC-like immunoprofile, representing a potential diagnostic pitfall in attempts to identify the site of origin of neoplasms of unknown primary site. In contrast with data on colorectal carcinoma, SATB2 expression is not associated with MMR status in SBAs. CK patterns influence patient survival, as CK7−/CK20− cancers show better prognosis, a behavior possibly due to the high rate of MMR-deficient SBAs within this subgroup.

Antibacterial self-assembled nanodrugs composed of berberine derivatives and rhamnolipids against Helicobacter pylori

The prevalence of infections with Helicobacter pylori (H. pylori) has progressively increased worldwide, which demonstrated to be closely correlated to its biofilm formation. H. pylori biofilms protect the bacteria by significantly decreasing their sensitivity to antibiotics. Moreover, H. pylori colonizes on the gastrointestinal tract epithelium which is covered by mucus layer, acting as another barrier to prevent antibacterial agents from reaching the colonization sites. Herein, we prepared four types of versatile self-assembled nanodrugs (BD/RHL NDs) containing lipophilic alkyl berberine derivatives (BDs) and rhamnolipids (RHL) to overcome the dual obstructions of both mucus layer and biofilms. Molecular dynamics simulations estimated that the driving forces for self-assembly of BD/RHL NDs were electrostatic and hydrophobic interactions. BD/RHL NDs, characterized by appropriate size, negative charge and enhanced hydrophilicity, successfully penetrated through mucus layer without interacting with mucins. In in vitro experiments, BD/RHL NDs exhibited substantial ability to eradicate H. pylori biofilms by destroying their extracellular polymeric substances (EPS) and killing planktonic H. pylori. Furthermore, BD/RHL NDs inhibited the adherence of H. pylori on both biotic and abiotic surfaces, therefore cut off the critical step of the biofilm re-formation which was associated with the recrudescence of infections. In an H. pylori-infected mice model, C10-BD/RHL NDs group showed 40 folds less remnant H. pylori and greater mucosal protection compared with the conventional clinical triple therapy. In conclusion, BD/RHL NDs could penetrate through mucus layer and effectively eradicate H. pylori biofilms in vitro and in vivo, providing a novel strategy for clinical treatment of biofilm-related infections.

Advillin is a tuft cell marker in the mouse alimentary tract

Tuft cells are a rare population of chemosensory cells at the mucosal surface epithelia of hollow organs. Their name-giving morphological feature is an apical tuft of stiff microvilli. Accordingly, the actin-binding protein, villin, was identified as one of the first tuft cell markers in immunohistochemical analysis. Unfortunately, villin expression is not restricted to tuft cells, but is also prominent e.g. in enterocytes, which limits the use of this gene as a marker and as an experimental tool to genetically target tuft cells. Here, we report that the villin-related protein, advillin, is a specific tuft cell marker in the gastro-intestinal and biliary tract epithelia. In situ hybridization and immunohistochemistry revealed that advillin expression, unlike villin, was restricted to solitary cholinergic tuft cells in the mucosal linings of the small and large intestine, and in the gall bladder. In the glandular stomach, villin and advillin mRNA were present in all epithelial cells, while detectable protein levels were confined to solitary tuft cells. Advillin expression was no longer detectable in the mucosa of the intestinal and biliary tract from Pou2f3 deficient mice that lack tuft cells. Finally, crossing Avil-Cre transgenic mice with a double-fluorescent reporter mouse line resulted in specific targeting of gastro-intestinal and biliary tuft cells. Our analysis introduces advillin as a selective marker and tool in histological and functional analysis of the alimentary tract tuft cell system.

Amphiphilic Star Polypept(o)ides as Nanomeric Vectors in Mucosal Drug Delivery.

Mucosal delivery across the gastrointestinal (GI) tract, airways, and buccal epithelia is an attractive mode of therapeutic administration, but the challenge is to overcome the mucus and epithelial barriers. Here, we present degradable star polypept(o)ides capable of permeating both barriers as a promising biomaterial platform for mucosal delivery. Star polypept(o)ides were obtained by the initiation of benzyl-l-glutamate N-carboxyanhydride (NCA) from an 8-arm poly(propyleneimine) (PPI) dendrimer, with subsequent chain extension with sarcosine NCA. The hydrophobic poly(benzyl-l-glutamate) (PBLG) block length was maintained at 20 monomers, while the length of the hydrophilic poly(sarcosine) (PSar) block ranged from 20-640 monomers to produce star polypept(o)ides with increasing hydrophilic: hydrophobic ratios. Transmission electron microscopy (TEM) images revealed elongated particles of ∼120 nm length, while dynamic light scattering (DLS) provided evidence of a decrease in the size of polymer aggregates in water with increasing poly(sarcosine) block length, with the smallest size obtained for the star PBLG20-b-PSar640. Fluorescein isothiocyanate (FITC)-conjugated PBLG20-b-PSar640 permeated artificial mucus and isolated rat mucus, as well as rat intestinal jejunal tissue mounted in Franz diffusion chambers. An apparent permeability coefficient (Papp) of 15.4 ± 3.1 ×10-6 cm/s for FITC-PBLG20-b-PSar640 was calculated from the transepithelial flux obtained with the apical-side addition of 7.5 mg polypept(o)ide to jejunal tissue over 2 h. This Papp could not be accounted for by flux of unconjugated FITC. Resistance to trypsin demonstrated the stability of FITC-labeled polypept(o)ide over 2 h, but enzymatic degradation at the mucus-epithelial interface or during flux could not be ruled out as contributing to the Papp. The absence of any histological damage to the jejunal tissue during the 2 h exposure suggests that the flux was not associated with overt toxicity.

57 Impact of weaning stress, disease, and diet on pig performance, intestinal function and integrity

Abstract Inevitably, pigs will experience stressors that antagonize lean tissue accretion, appetite, and feed conversion. Depending on the production system and age of the pig, these stressors commonly include weaning transition, diet changes, vaccination, enteric and respiratory pathogen challenges, activation of the HPA axis, and social stress. Additionally, the morbidity and mortality that accompany these stressors may be exacerbated by the illegalization of sub-therapeutic antibiotic use for growth promotion (AGPs) by the Veterinary Feed Directive. However, morbidity and mortality may also be mitigated by diet ingredients via direct and indirect modes of action on gastrointestinal health and function. The gastrointestinal tract has the vital but conflicting functions of nutrient and water absorption, while simultaneously regulating host mucosal defenses against noxious luminal contents such as microorganisms and their toxins. This puts the gastrointestinal tract epithelium and splenic tissue at the front line of nutrition, growth, and health of the pig in the new age of antimicrobial resistance concerns. As part of the body’s splanchnic tissues, the gastrointestinal tract is very metabolically active and has high utilization of luminal nutrients and energy. This utilization or “first pass metabolism” by intestinal epithelial and lamina propria cells can be a major determinant of the systemic or post-absorptive availability of glucose, essential and non-essential amino acids, and short and long chain fatty acids. This makes the gastrointestinal tract critically important to the growth and health of livestock and avian species. This paper will discuss the physiological impact of various stress challenges and nutrition on pig performance, gastrointestinal function and integrity.

Development and Evaluation of a Double-phase Multiple-unit Dosage form for Enhanced Insulin Intestinal Delivery

Background: The oral route is the most preferred route of administration for selfmedication, but poor membrane permeability and pre-systemic degradation are key challenges that need to be addressed. Objective: The purpose of this study was to develop and evaluate a double-phase, multiple-unit dosage form for enhanced delivery of insulin across the gastrointestinal tract epithelium. The dosage form was designed to provide increased membrane permeation by opening of tight junctions during the first phase followed by insulin delivery during the second phase. Methods: Different beads were prepared by means of extrusion-spheronisation. Combinations of different beads constituted the double-phase drug delivery systems. The one type of bead contained insulin as active ingredient and chitosan as mucoadhesive agent, while the other bead formulations contained each one of the following drug absorption enhancers: a bile salt mixture, sodium glycocholate, Aloe vera whole leaf extract or Aloe vera gel. The insulin delivery performance of the different doublephase delivery systems was evaluated across excised pig intestinal tissues in a Sweetana-Grass diffusion apparatus. Results: Initial exposure of the excised pig intestinal tissues to the absorption enhancer containing beads (first phase) was associated with enhanced intestinal transport of insulin (second phase) when compared to the control group. The insulin permeation enhancement effect across excised pig intestinal tissue was statistically significant in the case of pre-exposure to A. vera whole leaf extract and A. vera gel containing beads. Conclusion: Several double-phase multiple-unit drug delivery systems have the potential to effectively deliver insulin across the gastrointestinal epithelium. Keywords: Aloe vera, bile salt, chitosan, extrusion-spheronisation, insulin, paracellular permeation, permeation enhancement, sodium glycocholate, tight junction.

Transitional basal cells at the squamous-columnar junction generate Barrett's oesophagus.

In several organ systems the transitional zone between different types of epithelia is a hotspot for pre-neoplastic metaplasia and malignancy1–3. However, the cell-of-origin for the metaplastic epithelium and subsequent malignancy, remains obscure1–3. In the case of Barrett’s oesophagus (BE), intestinal metaplasia occurs at the gastro-oesophageal junction, where stratified squamous epithelium transitions into simple columnar cells4. Based on different experimental models, several alternative cell types have been proposed as the source of the metaplasia, but in all cases the evidence is inconclusive and no model completely mimics BE with the presence of intestinal goblet cells5–8. Here, we describe a novel transitional columnar epithelium with distinct basal progenitor cells (p63+ KRT5+ KRT7+) in the squamous-columnar junction (SCJ) in the upper gastrointestinal tract of the mouse. We use multiple models and lineage tracing strategies to show that this unique SCJ basal cell population serves as a source of progenitors for the transitional epithelium. Moreover, upon ectopic expression of CDX2 these transitional basal progenitors differentiate into intestinal-like epithelium including goblet cells, thus reproducing Barrett’s metaplasia. A similar transitional columnar epithelium is present at the transitional zones of other mouse tissues, including the anorectal junction, and, importantly, at the gastro-oesophageal junction in the human gut. Acid reflux-induced oesophagitis and the multilayered epithelium (MLE) believed to be a precursor of BE are both characterized by the expansion of the transitional basal progenitor cells. Taken together our findings reveal the presence of a previously unidentified transitional zone in the epithelium of the upper gastrointestinal tract and provide evidence that the p63+ KRT7+ basal cells in this zone are the cell-of-origin for MLE and BE.

The expression of bitter taste receptors (T2Rs) in the porcine gastrointestinal tract epithelium and smooth muscle

The expression of bitter taste receptors (T2Rs) in the porcine gastrointestinal tract epithelium and smooth muscle