Transforming growth factor-beta regulation of epithelial tight junction proteins enhances barrier function and blocks enterohemorrhagic Escherichia coli O157:H7-induced increased permeability

Molecular Motors in Blood-Brain Barrier Maintenance by Astrocytes

The blood-brain barrier (BBB) comprises distinct cell types, including endothelial cells, pericytes, and astrocytes, and is essential for central nervous system (CNS) homeostasis by selectively regulating molecular transport and maintaining integrity. In particular, astrocytes are essential for BBB function, as they maintain BBB integrity through their end-feet, which form a physical and biochemical interface that enhances endothelial cell function and barrier selectivity. Moreover, they secrete growth factors like vascular endothelial growth factor (VEGF) and transforming growth factor-beta (TGF-β), which regulate tight junction (TJ) proteins (e.g., claudins and occludins) crucial for limiting paracellular permeability. Molecular motors like kinesins, dynein, and myosins are essential for these astrocyte functions. By facilitating vesicular trafficking and protein transport, they are essential for various functions, including trafficking of junctional proteins to support BBB integrity, the proper mitochondria localization within astrocyte processes for efficient energy supply, the polarized distribution of aquaporin (AQP)-4 at astrocyte end-feet for regulating water homeostasis across the BBB, and the modulation of neuroinflammatory responses. Moreover, myosin motors modulate actomyosin dynamics to regulate astrocyte process outgrowth, adhesion, migration, and morphology, facilitating their functional roles. Thus, motor protein dysregulation in astrocytes can compromise BBB function and integrity, increasing the risk of neurodegeneration. This review explores the complex interplay between astrocytes and molecular motors in regulating BBB homeostasis, which represents an attractive but poorly explored area of research.

Evaluation of mucosal adjuvants to chitosan-nanoparticle-based oral subunit vaccine for controlling salmonellosis in broilers

Salmonellosis, a gastrointestinal disease, continues to be one of the major public health concerns worldwide. Poultry meat and eggs are recognized as the major source of Salmonella food poisoning in humans. Our study evaluated the protective efficacy of mannose-conjugated chitosan-nanoparticle (mChitosan-NP)-based subunit vaccine, consisting of immunogenic outer membrane proteins and flagella of Salmonella Enteritidis [mChitosan (OMP+FLA)/FLA-NP], coadministered orally with potent mucosal adjuvants to reduce the colonization of S. Enteritidis in the intestines of broiler chickens. We evaluated the adjuvant effects of three different doses of two well-known mucosal adjuvants, c-di-GMP (stimulator of interferon gene agonist) and whole cell lysate (WCL) of Mycobacterium smegmatis, to improve the efficacy of mChitosan (OMP+FLA)/FLA-NP vaccine. Our data reaffirmed the potent adjuvanticity of both of these adjuvants and identified their optimal dose when entrapped in mChitosan-NP to potentiate the immunogenicity and efficacy of orally delivered mChitosan (OMP+FLA)/FLA-NP vaccine. The physical characteristics of mChitosan (OMP+FLA)/FLA-NP, mChitosan-GMP/FLA-NP, and mChitosan-WCL/FLA-NP formulations revealed a high positive charge (Zeta potential +20-25 mV), size 235-260 nm, and polydispersity index 0.35-0.52, which are conducive for oral delivery. The efficacy in chickens that received oral administration with a combination of the vaccine-adjuvant formulations was evaluated by challenging with Salmonella Enteritidis. Our data showed that mChitosan (OMP+FLA)/FLA-NP WCL at 10 µg/dose formulation consistently reduced the S. Enteritidis load by over 0.5 log10 comparable to a commercial live vaccine at post-challenge days 4 and 10. Immunologically, we observed enhanced systemic and mucosal antibody and cellular (B cells and T-helper cells) immune responses as well as upregulation of expression of immune cytokine genes IFN-γ, TGF-β, and IL-17 in the cecal tonsils of adjuvanted mChitosan-NP Salmonella-subunit-vaccinated birds. Overall, particularly the mucosal adjuvant WCL consistently enhanced the efficacy of mChitosan (OMP+FLA)/FLA-NP vaccine by inducing effective immune responses.

Calcitonin gene-related peptide promotes epithelial reparative and anticolitic functions of IL-4 educated human macrophages

Interleukin-4 activated human macrophages [M(IL4)s] promote epithelial wound healing and exert an anticolitic effect in a murine model. Blood monocyte-derived M(IL4)s from healthy donors and individuals with Crohn's disease had increased mRNA expression of the calcitonin gene-related peptide (CGRP) receptor chain, receptor activity modifying protein-1 (RAMP1), raising the issue of neural modulation of the M(IL4)s reparative function. Thus, human M(IL4)s were treated with CGRP and the cells' phagocytotic, epithelial wound repair and anticolitic functions were assessed. Initial studies confirmed upregulation of expression of the CGRP receptor, which was localized to the cell surface and was functional as determined by CGRP-evoked increases in cAMP. M(IL4,CGRP)s had increased mannose receptor (CD206) and FcγRIIa (CD32a) mRNA expression, a subtle, but significant, increase in phagocytosis and decreased chemokine production following the exposure to Escherichia coli. When delivered systemically (106 cells IP) to oxazolone-treated rag1-/- mice, M(IL4,CGRP) had an anticolitic effect superior to M(IL4)s from the same blood donor. Conditioned medium (CM) from M(IL4,CGRP) had increased amounts of transforming growth factor (TGF)-β and increased wound-healing capacity compared with matched M(IL4)-CM in the human CaCo2 epithelial cell line in-vitro wounding assay. Moreover, M(IL4,CGRP)s displayed increased cyclooxygenase (COX)-1 and prostaglandin D2 (PGD2), and CM from M(IL4,CGRP)s treated with indomethacin or SC-560 to inhibit COX-1 activity failed to promote repair of wounded CaCo2 cell monolayers. These data confirm the human M(IL4)s' anticolitic effect that was enhanced by CGRP and may be partially dependent on macrophage COX-1/PGD2 activity. Thus, input from neurone-derived molecules is a local modifier capable of boosting the anticolitic effect of autologous M(IL4) transfer.NEW & NOTEWORTHY A novel pathway is identified whereby interleukin-4-educated human macrophages [M(IL4)s] exposed to calcitonin gene-related peptide (CGRP) reduce oxazolone-induced colitis and promote epithelial wound healing in vitro through COX1-dependent signaling. Support is provided for the concept of macrophage transfer to treat enteric inflammation where neuroimmune interaction, in this case CGRP neuropeptide, produced under inflammatory conditions will reinforce the anticolitic and wound repair capacity of M(IL4) autologous-based therapy for IBD treatment.

Neisseria gonorrhoeae induces local secretion of IL-10 at the human cervix to promote colonization

Gonorrhea, caused by the human-restricted pathogen Neisseria gonorrhoeae, is a commonly reported sexually transmitted infection. Since most infections in women are asymptomatic, the true number of infections is likely much higher than reported. How gonococci (GC) colonize women's cervixes without triggering symptoms remains elusive. Using a human cervical tissue explant model, we found that GC inoculation increased the local secretion of both proinflammatory (IL-1β and TNF-α) and antiinflammatory (IL-10) cytokines during the first 24 hours of infection. Cytokine induction required GC expression of Opa isoforms that bind the host receptors carcinoembryonic antigen-related cell adhesion molecules (CEACAMs). GC inoculation induced NF-κB activation in both cervical epithelial and subepithelial cells. However, inhibition of NF-κB activation, which reduced GC-induced IL-1β and TNF-α, did not affect GC colonization. Neutralizing IL-10 or blocking IL-10 receptors by antibodies reduced GC colonization by increasing epithelial shedding and epithelial cell-cell junction disassembly. Inhibition of the CEACAM downstream signaling molecule SHP1/2, which reduced GC colonization and increased epithelial shedding, decreased GC-induced IL-10 secretion. These results show that GC induce local secretion of IL-10, a potent antiinflammatory cytokine, at the cervix by engaging the host CEACAMs to prevent GC-colonizing epithelial cells from shedding, providing a potential mechanism for GC asymptomatic colonization in women.

The gut homeostasis-immune system axis: novel insights into rheumatoid arthritis pathogenesis and treatment

Rheumatoid arthritis is a widely prevalent autoimmune bone disease that imposes a significant burden on global healthcare systems due to its increasing incidence. In recent years, attention has focused on the interaction between gut homeostasis and the immune system, particularly in relation to bone health. Dysbiosis, which refers to an imbalance in the composition and function of the gut microbiota, has been shown to drive immune dysregulation through mechanisms such as the release of pro-inflammatory metabolites, increased gut permeability, and impaired regulatory T cell function. These factors collectively contribute to immune system imbalance, promoting the onset and progression of Rheumatoid arthritis. Dysbiosis induces both local and systemic inflammatory responses, activating key pro-inflammatory cytokines such as tumor necrosis factor-alpha, Interleukin-6, and Interleukin-17, which exacerbate joint inflammation and damage. Investigating the complex interactions between gut homeostasis and immune regulation in the context of Rheumatoid arthritis pathogenesis holds promise for identifying new therapeutic targets, revealing novel mechanisms of disease progression, and offering innovative strategies for clinical treatment.

Outer Membrane Vesicles Derived from Adherent-Invasive Escherichia coli Induce Inflammatory Response and Alter the Gene Expression of Junction-Associated Proteins in Human Intestinal Epithelial Cells

Adherent-invasive Escherichia coli (AIEC) pathobionts, which are characterized by their ability to adhere to and invade intestinal epithelial cells, are associated with the etiopathogenesis of inflammatory bowel diseases (IBDs). Outer membrane vesicles (OMVs) released by AIEC strains can facilitate the interaction of these bacteria with host cells through delivering bacterial effectors. The aim of this study was to determine the ability of OMVs derived from AIEC strain LF82 to induce the host immune response, leading to production of proinflammatory cytokines and also altering the gene expression of junction-associated proteins in the human epithelial colorectal adenocarcinoma Caco-2 cell line. OMVs were extracted from AIEC strain LF82, and the cell viability of Caco-2 cells treated with these vesicles was assessed by MTT assay. The morphology and size distribution of vesicles were analyzed using transmission electron microscopy and dynamic light scattering, respectively. Gene expression of occludin, ZO-1, claudin-2, E-cadherin, TLR-2, and TLR-4 in response to OMVs was assessed in Caco-2 cells by RT-qPCR. Moreover, the secretion of IL-8 and TNF-α into the supernatant of Caco-2 cells upon treatment with OMVs was measured using ELISA. Our results demonstrated that OMVs upregulated the gene expression level of TLRs and also altered the gene expression level of junction-associated proteins. OMVs derived from AIEC may play a major role in the promotion of intestinal inflammation and epithelial barrier dysfunction. However, further investigations are needed to elucidate the putative role of OMVs in the pathogenesis of AIEC and IBD.

Systemic Effects of a Phage Cocktail on Healthy Weaned Piglets

Numerous studies have demonstrated that bacteriophages (phages) can effectively treat intestinal bacterial infections. However, research on the impact of phages on overall body health once they enter the intestine is limited. This study utilized weaned piglets as subjects to evaluate the systemic effects of an orally administered phage cocktail on their health. Twelve 21-day-old weaned piglets were divided into control (CON) and phage gavage (Phages) groups. The phage cocktail consisted of five lytic phages, targeting Salmonella enterica serovar Choleraesuis (S. choleraesuis), Enteropathogenic Escherichia coli (EPEC), and Shiga tox-in-producing Escherichia coli (STEC). The phages group received 10 mL of phage cocktail orally for 20 consecutive days. The results show that the phage gavage did not affect the piglets' growth performance, serum biochemical indices, or most organ indices, except for the pancreas. However, the impact on the intestine was complex. Firstly, although the pancreatic index decreased, it did not affect the secretion of digestive enzymes in the intestine. Secondly, phages increased the pH of jejunum chyme and relative weight of the ileum, and enhanced intestinal barrier function without affecting the morphology of the intestine. Thirdly, phages did not proliferate in the intestine, but altered the intestinal microbiota structure and increased concentrations of microbial metabolites isobutyric acid and isovaleric acid in the colonic chyme. In addition, phages impacted the immune status, significantly increasing serum IgA, IgG, and IgM, as well as serum and intestinal mucosal IFN-γ, IL-1β, IL-17, and TGF-β, and decreasing IL-4 and IL-10. They also activated toll-like receptors TLR-4 and TLR-9. Apart from an increase in basophil numbers, the counts of other immune cells in the blood did not change. This study indicates that the impact of phages on body health is complex, especially regarding immune status, warranting further attention. Short-term phage gavage did not have significant negative effects on health but could enhance intestinal barrier function.

Milk: A Natural Guardian for the Gut Barrier

The gut barrier plays an important role in health maintenance by preventing the invasion of dietary pathogens and toxins. Disruption of the gut barrier can cause severe intestinal inflammation. As a natural source, milk is enriched with many active constituents that contribute to numerous beneficial functions, including immune regulation. These components collectively serve as a shield for the gut barrier, protecting against various threats such as biological, chemical, mechanical, and immunological threats. This comprehensive review delves into the active ingredients in milk, encompassing casein, α-lactalbumin, β-lactoglobulin, lactoferrin, the milk fat globular membrane, lactose, transforming growth factor, and glycopeptides. The primary focus is to elucidate their impact on the integrity and function of the gut barrier. Furthermore, the implications of different processing methods of dairy products on the gut barrier protection are discussed. In conclusion, this study aimed to underscore the vital role of milk and dairy products in sustaining gut barrier health, potentially contributing to broader perspectives in nutritional sciences and public health.

Potassium diformate alleviated inflammation of IPEC-J2 cells infected with EHEC

Potassium diformate (KDF) is a kind of formate, which possesses the advantages of antimicrobial activity, growth promotion and preventing diarrhea in weaned piglets. However, the researches of KDF in animal production mostly focused on apparent indexes such as growth performance and the mechanisms of KDF on intestinal health have not been reported. Thus, porcine small intestinal epithelial cells (IPEC-J2) infected with Enterohemorrhagic Escherichia coli (EHEC) was used to investigate the role of KDF on alleviating intestinal inflammation in this study. The 0.125 mg/mL KDF treated IPEC-J2 cells for 6 h and IPEC-J2 cells challenged with 5 × 107 CFU/mL EHEC for 4 h were confirmed as the optimum concentration and time for the following experiment. The subsequent experiment was divided into four groups: control group (CON), EHEC group, KDF group, KDF+EHEC group. The results showed that KDF increased the cell viability and the gene expression levels of SGLT3 and TGF-β, while decreased the content of IL-1β compared with the CON group. The cell viability and the gene expressions of SGLT1, SGLT3, GLUT2, Claudin-1, Occludin and TGF-β, and the protein expression of ZO-1 in EHEC group were lower than those in CON group, whereas the gene expressions of IL-1β, TNF, IL-8 and TLR4, and the level of phosphorylation NF-кB protein were increased. Pretreatment with KDF reduced the content of IgM and IL-1β, the gene expressions of IL-1β, TNF, IL-8 and TLR4 and the level of phosphorylation NF-кB protein, and increased the gene expression of TGF-β and the protein expression of Occludin in IPEC-J2 cells infected EHEC. In conclusion, 0.125 mg/mL KDF on IPEC-J2 cells for 6 h had the beneficial effects on ameliorating the intestinal inflammation because of reduced pro-inflammatory cytokines and enhanced anti-inflammatory cytokines through regulating NF-кB signaling pathway under the EHEC challenge.

Olive Mill Waste-Water Extract Enriched in Hydroxytyrosol and Tyrosol Modulates Host-Pathogen Interaction in IPEC-J2 Cells

The dietary supplementation of olive oil by-products, including olive mill waste-water (OMWW) in animal diets, is a novel application that allows for their re-utilization and recycling and could potentially decrease the use of antibiotics, antimicrobial resistance risk in livestock species, and the occurrence of intestinal diseases. Salmonella serovar typhimurium is one of the most widespread intestinal pathogens in the world, causing enterocolitis in pigs. The aim of this study was to investigate the effect of an OMWW extract enriched in polyphenols (hydroxytyrosol and tyrosol) in the immune response of an intestinal porcine epithelial cell line (IPEC-J2) following S. typhimurium infection. Cells were pre-treated with OMWW-extract polyphenols (OMWW-EP, 0.35 and 1.4 µg) for 24 h and then infected with S. typhimurium for 1 h. We evaluated bacterial invasiveness and assayed IPEC-J2 gene expression with RT-qPCR and cytokine release with an ELISA test. The obtained results showed that OMWW-EP (1.4 µg) significantly reduced S. typhimurium invasiveness; 0.35 µg decreased the IPEC-J2 gene expression of IL1B, MYD88, DEFB1 and DEFB4A, while 1.4 µg down-regulated IL1B and DEFB4A and increased TGFB1. The cytokine content was unchanged in infected cells. This is the first study demonstrating the in vitro immunomodulatory and antimicrobial activity of OMWW extracts enriched in polyphenols, suggesting a protective role of OMWW polyphenols on the pig intestine and their potential application as feed supplements in farm animals such as pigs.

Characterization of Bovine Intraepithelial T Lymphocytes in the Gut

Intraepithelial T lymphocytes (T-IELs), which constitute over 50% of the total T lymphocytes in the animal, patrol the mucosal epithelial lining to defend against pathogen invasion while maintaining gut homeostasis. In addition to expressing T cell markers such as CD4 and CD8, T-IELs display T cell receptors (TCR), including either TCRαβ or TCRγδ. Both humans and mice share similar T-IEL subsets: TCRγδ+, TCRαβ+CD8αα+, TCRαβ+CD4+, and TCRαβ+CD8αβ+. Among these subsets, human T-IELs are predominantly TCRαβ+ (over 80%), whereas those in mice are mostly TCRγδ+ (~60%). Of note, the majority of the TCRγδ+ subset expresses CD8αα in both species. Although T-IELs have been extensively studied in humans and mice, their profiles in cattle have not been well examined. Our study is the first to characterize bovine T-IELs using flow cytometry, where we identified several distinct features. The percentage of TCRγδ+ was comparable to that of TCRαβ+ T-IELs (both ~50% of CD3+), and the majority of bovine TCRγδ+ T-IELs did not express CD8 (CD8-) (above 60%). Furthermore, about 20% of TCRαβ+ T-IELs were CD4+CD8αβ+, and the remaining TCRαβ+ T-IELs were evenly distributed between CD4+ and CD8αβ+ (~40% of TCRαβ+ T-IELs each) with no TCRαβ+CD8αα+ identified. Despite these unique properties, bovine T-IELs, similar to those in humans and mice, expressed a high level of CD69, an activation and tissue-retention marker, and a low level of CD62L, a lymphoid adhesion marker. Moreover, bovine T-IELs produced low levels of inflammatory cytokines such as IFNγ and IL17A, and secreted small amounts of the immune regulatory cytokine TGFβ1. Hence, bovine T-IELs' composition largely differs from that of human and mouse, with the dominance of the CD8- population among TCRγδ+ T-IELs, the substantial presence of TCRαβ+CD4+CD8αβ+ cells, and the absence of TCRαβ+CD8αα+ T-IELs. These results provide the groundwork for conducting future studies to examine how bovine T-IELs respond to intestinal pathogens and maintain the integrity of the gut epithelial barrier in animals.

Terminal differentiation of villus tip enterocytes is governed by distinct Tgfβ superfamily members

The protective and absorptive functions of the intestinal epithelium rely on differentiated enterocytes in the villi. The differentiation of enterocytes is orchestrated by sub-epithelial mesenchymal cells producing distinct ligands along the villus axis, in particular Bmps and Tgfβ. Here, we show that individual Bmp ligands and Tgfβ drive distinct enterocytic programs specific to villus zonation. Bmp4 is expressed from the centre to the upper part of the villus and activates preferentially genes connected to lipid uptake and metabolism. In contrast, Bmp2 is produced by villus tip mesenchymal cells and it influences the adhesive properties of villus tip epithelial cells and the expression of immunomodulators. Additionally, Tgfβ induces epithelial gene expression programs similar to those triggered by Bmp2. Bmp2-driven villus tip program is activated by a canonical Bmp receptor type I/Smad-dependent mechanism. Finally, we establish an organoid cultivation system that enriches villus tip enterocytes and thereby better mimics the cellular composition of the intestinal epithelium. Our data suggest that not only a Bmp gradient but also the activity of individual Bmp drives specific enterocytic programs.

Commensal Escherichia coli Strains of Bovine Origin Competitively Mitigated Escherichia coli O157:H7 in a Gnotobiotic Murine Intestinal Colonization Model with or without Physiological Stress

Cattle are a primary reservoir of enterohemorrhagic Escherichia coli (EHEC) O157:H7. Currently, there are no effective methods of eliminating this important zoonotic pathogen from cattle, and colonization resistance in relation to EHEC O157:H7 in cattle is poorly understood. We developed a gnotobiotic EHEC O157:H7 murine model to examine aspects of the cattle pathogen-microbiota interaction, and to investigate competitive suppression of EHEC O157:H7 by 18 phylogenetically distinct commensal E. coli strains of bovine origin. As stress has been suggested to influence enteric colonization by EHEC O157:H7 in cattle, corticosterone administration (±) to incite a physiological stress response was included as an experimental variable. Colonization of the intestinal tract (IT) of mice by the bovine EHEC O157:H7 strain, FRIK-2001, mimicked characteristics of bovine IT colonization. In this regard, FRIK-2001 successfully colonized the IT and temporally incited minimal impacts on the host relative to other EHEC O157:H7 strains, including on the renal metabolome. The presence of the commensal E. coli strains decreased EHEC O157:H7 densities in the cecum, proximal colon, and distal colon. Moreover, histopathologic changes and inflammation markers were reduced in the distal colon of mice inoculated with commensal E. coli strains (both propagated separately and communally). Although stress induction affected the behavior of mice, it did not influence EHEC O157:H7 densities or disease. These findings support the use of a gnotobiotic murine model of enteric bovine EHEC O157:H7 colonization to better understand pathogen-host-microbiota interactions toward the development of effective on-farm mitigations for EHEC O157:H7 in cattle, including the identification of bacteria capable of competitively colonizing the IT.

Calcineurin B1 Deficiency Reduces Proliferation, Increases Apoptosis, and Alters Secretion in Enteric Glial Cells of Mouse Small Intestine in Culture

To investigate the roles of calcineurin (CN) in glial cells, we previously generated conditional knockout (CKO) mice lacking CNB1 in glial cells. Because these CKO mice showed dysfunction and inflammation of the small intestine in addition to growth impairment and postweaning death, we have focused on enteric glial cells (EGCs) in the small intestine. In this study, we examined the effects of CNB1 deficiency on the proliferation and survival of EGCs and the expression and secretion of EGC-derived substances in culture to reveal the mechanisms of how CNB1 deficiency leads to dysfunction and inflammation of the small intestine. In primary myenteric cultures of the small intestine, EGCs from the CKO mice showed reduced proliferation and increased apoptosis compared with EGCs from control mice. In purified EGC cultures from the CKO mice, Western blot analysis showed increased expression of S100B, iNOS, GFAP, and GDNF, and increased phosphorylation of NF-κB p65. In the supernatants of purified EGC cultures from the CKO mice, ELISA showed reduced secretion of TGF-β1. In contrast, GDNF secretion was not altered in purified EGC cultures from the CKO mice. Furthermore, treatment with an S100B inhibitor partially rescued the CKO mice from growth impairment and postweaning death in vivo. In conclusion, CNB1 deficiency leads to reduced proliferation and increased apoptosis of EGCs and abnormal expression and secretion of EGC-derived substances, which may contribute to dysfunction and inflammation of the small intestine.

A spike in circulating cytokines TNF-α and TGF-β alters barrier function between vascular and musculoskeletal tissues

Molecular transport between the circulatory and musculoskeletal systems regulates articular joint physiology in health and disease. Osteoarthritis (OA) is a degenerative joint disease linked to systemic and local inflammation. Inflammatory events involve cytokines, which are secreted by cells of the immune system and modulate molecular transport across tissue interfaces (referred to as tight junction [TJ] barrier function). In a previous study from our group, OA knee joint tissues were shown to exhibit size separation of different sized molecules delivered as a single bolus to the heart (Ngo et al. in Sci. Rep. 8:10254, 2018). Here, in a follow up study of parallel design, we test the hypothesis that two common cytokines, with multifaceted roles in the etiology of osteoarthritis as well as immune state in general, modulate the barrier function properties of joint tissue interfaces. Specifically, we probe the effect of an acute cytokine increase (spike) on molecular transport within tissues and across tissue interfaces of the circulatory and musculoskeletal systems. A single bolus of fluorescent-tagged 70 kDa dextran, was delivered intracardially, either alone, or with either the pro-inflammatory cytokine TNF-α or the anti-inflammatory cytokine TGF-β, to skeletally mature (11 to 13-month-old) guinea pigs (Dunkin-Hartley, a spontaneous OA animal model). After five minutes' circulation, whole knee joints were serial sectioned and fluorescent block face cryo-imaged at near-single-cell resolution. The 70 kDa fluorescent-tagged tracer is analogous in size to albumin, the most prevalent blood transporter protein, and quantification of tracer fluorescence intensity gave a measure of tracer concentration. Within five minutes, a spike (acute doubling) in circulating cytokines TNF-α or TGF-β significantly disrupted barrier function between the circulatory and musculoskeletal systems, with barrier function essentially abrogated in the TNF-α group. In the entire volume of the joint (including all tissue compartments and the bounding musculature), tracer concentration was significantly decreased in the TGF-β- and TNF-α- compared to the control-group. These studies implicate inflammatory cytokines as gatekeepers for molecular passage within and between tissue compartments of our joints and may open new means to delay the onset and mitigate the progression of degenerative joint diseases such as OA, using pharmaceutical and/or physical measures.

Gut epithelial barrier dysfunction in lupus triggers a differential humoral response against gut commensals

Introduction

Systemic lupus erythematosus is an autoimmune disease with multisystemic involvement including intestinal inflammation. Lupus-associated intestinal inflammation may alter the mucosal barrier where millions of commensals have a dynamic and selective interaction with the host immune system. Here, we investigated the consequences of the intestinal inflammation in a TLR7-mediated lupus model.

Methods

IgA humoral and cellular response in the gut was measured. The barrier function of the gut epithelial layer was characterised. Also, microbiota composition in the fecal matter was analysed as well as the systemic humoral response to differential commensals.

Results

The lupus-associated intestinal inflammation modifies the IgA+ B cell response in the gut-associated lymphoid tissue in association with dysbiosis. Intestinal inflammation alters the tight junction protein distribution in the epithelial barrier, which correlated with increased permeability of the intestinal barrier and changes in the microbiota composition. This permeability resulted in a differential humoral response against intestinal commensals.

Discussion

Lupus development can cause alterations in microbiota composition, allowing specific species to colonize only the lupus gut. Eventually, these alterations and the changes in gut permeability induced by intestinal inflammation could lead to bacterial translocation.

Acetic acid-induced colitis modulating potential of total crude alkaloidal extract of Picralima nitida seeds in rats

PURPOSE

The total crude alkaloidal extract of Picralima nitida seeds (PNE) is known to possess anti-inflammatory activity among other therapeutic benefits although its benefits in colitis has not been investigated. The current study therefore seeks to investigate the anti-colitis potential of PNE using acetic acid-induced colitis model in rats.

METHODS

Sprague Dawley rats were treated with oral 500 mg/kg sulphasalazine or 30, 100, and 300 mg/kg of PNE daily for 8 days with induction of colitis on the fourth day with acetic acid. Rats were killed 24 h after the last treatment and whole blood was obtained from the jugular vein for hematological analysis and biochemical assays. Colons were extirpated for assessment of macroscopic and histological damage to the colon.

RESULTS

Treatment with PNE protected against colonic injury induced with acetic acid by decreasing mucosal ulceration, epithelial erosion, inflammatory cell infiltration, and colonic edema. Thus, PNE preserved mucosal architecture and suppressed goblet cells depletion. Moreover, treatment with PNE was associated with improved hematological parameters and reductions in the expression of serum tumor necrosis factor-alpha, interleukin-1β, and p38 mitogen-activated protein kinase. Also, PNE treatment exerted antioxidant effects by reducing nitric oxide production and increasing glutathione levels. In addition, PNE inhibited colonic lipid peroxidation by decreasing myeloperoxidase activity and malondialdehyde production.

CONCLUSION

It can be concluded that PNE attenuates intestinal oxidative and inflammatory damages following intrarectal acetic acid challenge. Thus, demonstrates potential for use in chronic intestinal inflammatory diseases such as ulcerative colitis.

Cytokines and intestinal epithelial permeability: A systematic review

BACKGROUND

The intestinal mucosa is composed of a well-organized epithelium, acting as a physical barrier to harmful luminal contents, while simultaneously ensuring absorption of physiological nutrients and solutes. Increased intestinal permeability has been described in various chronic diseases, leading to abnormal activation of subepithelial immune cells and overproduction of inflammatory mediators. This review aimed to summarize and evaluate the effects of cytokines on intestinal permeability.

METHODS

A systematic review of the literature was performed in the Medline, Cochrane and Embase databases, up to 01/04/2022, to identify published studies assessing the direct effect of cytokines on intestinal permeability. We collected data on the study design, the method of assessment of intestinal permeability, the type of intervention and the subsequent effect on gut permeability.

RESULTS

A total of 120 publications were included, describing a total of 89 in vitro and 44 in vivo studies. TNFα, IFNγ or IL-1β were the most frequently studied cytokines, inducing an increase in intestinal permeability through a myosin light-chain-mediated mechanism. In situations associated with intestinal barrier disruption, such as inflammatory bowel diseases, in vivo studies showed that anti-TNFα treatment decreased intestinal permeability while achieving clinical recovery. In contrast to TNFα, IL-10 decreased permeability in conditions associated with intestinal hyperpermeability. For some cytokines (e.g. IL-17, IL-23), results are conflicting, with both an increase and a decrease in gut permeability reported, depending on the study model, methodology, or the studied conditions (e.g. burn injury, colitis, ischemia, sepsis).

CONCLUSION

This systematic review provides evidence that intestinal permeability can be directly influenced by cytokines in numerous conditions. The immune environment probably plays an important role, given the variability of their effect, according to different conditions. A better understanding of these mechanisms could open new therapeutic perspectives for disorders associated with gut barrier dysfunction.

Role of Muscarinic Acetylcholine Receptors in Intestinal Epithelial Homeostasis: Insights for the Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis, is an intestinal disorder that causes prolonged inflammation of the gastrointestinal tract. Currently, the etiology of IBD is not fully understood and treatments are insufficient to completely cure the disease. In addition to absorbing essential nutrients, intestinal epithelial cells prevent the entry of foreign antigens (micro-organisms and undigested food) through mucus secretion and epithelial barrier formation. Disruption of the intestinal epithelial homeostasis exacerbates inflammation. Thus, the maintenance and reinforcement of epithelial function may have therapeutic benefits in the treatment of IBD. Muscarinic acetylcholine receptors (mAChRs) are G protein-coupled receptors for acetylcholine that are expressed in intestinal epithelial cells. Recent studies have revealed the role of mAChRs in the maintenance of intestinal epithelial homeostasis. The importance of non-neuronal acetylcholine in mAChR activation in epithelial cells has also been recognized. This review aimed to summarize recent advances in research on mAChRs for intestinal epithelial homeostasis and the involvement of non-neuronal acetylcholine systems, and highlight their potential as targets for IBD therapy.

Perinatal exposure to high concentration glyphosate-based herbicides induces intestinal apoptosis by activating endoplasmic reticulum stress in offspring

Glyphosate-based herbicides (GBHs), the most widely used pesticide worldwide, have been reported to impair organ function in humans and animals. However, research on the effect of maternal GBHs exposure on the intestinal health of offspring has received little attention. Based on the glyphosate limits defined by Codex Alimentarius Commission and European Food Safety Authority, this study established pregnant sow exposure models to investigate the influence of low (L-GBHs, 20 mg/kg) and high concentration GBHs (H-GBHs, 100 mg/kg) on the intestinal health of offspring and proposed the protective mechanism mediated by betaine. The results showed that the intestinal morphology and barrier function of suckling piglets were damaged in the H-GBHs group. H-GBHs increased the activity of glutathione peroxidase (GPX) and levels of methane dicarboxylic aldehyde (MDA), hydrogen peroxide (H₂O₂) and inflammatory factors (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10)) in suckling piglets and activated Nrf2-mediated antioxidant signaling pathway. Subsequently, we found that exposure to H-GBHs triggered endoplasmic reticulum stress (ERS) and further induced apoptosis by upregulating the expression of Bcl-2-associated X protein (Bax), Caspase3, Caspase9 and Caspase12. Moreover, H-GBHs exposure perturbed mitochondrial membrane fusion and electron transport in mitochondrial respiratory chains by increasing the mRNA expression of mitofusin-2 (MFN2) and succinate dehydrogenase subunit A (SDHA), causing mitochondrial dysfunction. Dietary supplementation with betaine provided modest protection against GBHs-induced intestinal damage in suckling piglets. These findings reveal the mechanism of GBHs-induced intestinal damage in offspring, improving our understanding of the risk of GBHs exposure in pregnant women and suggesting the potential protective effects of betaine against GBHs poisoning.

C3a/C3aR Affects the Propagation of Cryptosporidium parvum in the Ileum Tissues of Mice by Regulating the Gut Barrier, Cell Proliferation, and CD4+ T Cell Main Effectors

Cryptosporidium parvum is an important zoonotic protozoon that threatens the health of humans and animals, but the interaction mechanisms between C. parvum and hosts are poorly understood. Our previous study indicated that the expression levels of C3a and C3aR were up-regulated in mice during C. parvum infection, but the mechanisms of C3a/C3aR signaling during C. parvum infection have not been elucidated. In the present study, an optimized BALB/c suckling mouse model infected with C. parvum was used to explore the function of C3a/C3aR signaling during C. parvum infection. The expression levels of C3aR in the ileum tissues of mice infected with C. parvum were analyzed using real-time PCR, Western blot and immunohistochemistry. The mRNA levels of the Cryptosporidium 18S rRNA gene, tight junction proteins (zo-1, claudin 3, and occludin), intestinal stem cell marker lgr5, cell proliferation marker ki67, Th1 cell-related cytokine ifn-γ, and Treg cell-related cytokine tgf-β in mouse ileum tissues were analyzed by real-time PCR. The pathological injury of ileal mucosa was examined by histopathology analysis. The mRNA expression levels of Cryptosporidium 18S rRNA gene were significantly up-regulated in the ileum tissues of C3aR-inhibited mice during C. parvum infection. Meanwhile, histopathology analysis of ileal mucosa in mice showed that inhibition of C3aR significantly aggravated the changes in villus length, villus diameter, mucosal thickness and the ratio of villus length to crypt depth during C. parvum infection. Further studies found inhibition of C3aR aggravated the down-regulation of occludin at most time points during C. parvum infection. The mRNA levels of ki67 and lgr5 in the ileum tissues of mice infected with C. parvum were significantly down-regulated. Inhibition of C3aR significantly down-regulated the mRNA expression levels of lgr5 at most time points, but significantly up-regulated the mRNA expression levels of ki67 at most time points. The mRNA expression levels of ifn-γ and tgf-β were significantly up-regulated and down-regulated in the ileum tissues of mice infected with C. parvum, respectively. However, inhibition of C3aR significantly increased the mRNA expression levels of ifn-γ and tgf-β in the ileum tissues of mice infected with C. parvum. Taken together, C3a/C3aR signaling could possibly affect the propagation of C. parvum in mouse ileum tissues by regulating the gut barrier, cell proliferation and CD4⁺ T cell main effectors, which would contribute to our understanding of the interaction between Cryptosporidium and hosts.

Direct Action of Non-Digestible Oligosaccharides against a Leaky Gut

The epithelial monolayer is the primary determinant of mucosal barrier function, and tight junction (TJ) complexes seal the paracellular space between the adjacent epithelial cells and represent the main "gate-keepers" of the paracellular route. Impaired TJ functionality results in increased permeation of the "pro-inflammatory" luminal contents to the circulation that induces local and systemic inflammatory and immune responses, ultimately triggering and/or perpetuating (chronic) systemic inflammatory disorders. Increased gut leakiness is associated with intestinal and systemic disease states such as inflammatory bowel disease and neurodegenerative diseases such as Parkinson's disease. Modulation of TJ dynamics is an appealing strategy aiming at inflammatory conditions associated with compromised intestinal epithelial function. Recently there has been a growing interest in nutraceuticals, particularly in non-digestible oligosaccharides (NDOs). NDOs confer innumerable health benefits via microbiome-shaping and gut microbiota-related immune responses, including enhancement of epithelial barrier integrity. Emerging evidence supports that NDOs also exert health-beneficial effects on microbiota independently via direct interactions with intestinal epithelial and immune cells. Among these valuable features, NDOs promote barrier function by directly regulating TJs via AMPK-, PKC-, MAPK-, and TLR-associated pathways. This review provides a comprehensive overview of the epithelial barrier-protective effects of different NDOs with a special focus on their microbiota-independent modulation of TJs.

How copper can impact pig growth: comparing the effect of copper sulfate and monovalent copper oxide on oxidative status, inflammation, gene abundance, and microbial modulation as potential mechanisms of action

The beneficial effect of elevated concentrations of copper (Cu) on growth performance of pigs has been already demonstrated; however, their mechanism of action is not fully discovered. The objective of the present experiment was to investigate the effects of including Cu from copper sulfate (CuSO4) or monovalent copper oxide (Cu2O) in the diet of growing pigs on oxidative stress, inflammation, gene abundance, and microbial modulation. We used 120 pigs with initial body weight (BW) of 11.5 ± 0.98 kg in 2 blocks of 60 pigs, 3 dietary treatments, 5 pigs per pen, and 4 replicate pens per treatment within each block for a total of 8 pens per treatment. Dietary treatments included the negative control (NC) diet containing 20 mg Cu/kg and 2 diets in which 250 mg Cu/kg from CuSO4 or Cu2O was added to the NC. On day 28, serum samples were collected from one pig per pen and this pig was then euthanized to obtain liver samples for the analysis of oxidative stress markers (Cu/Zn superoxide dismutase, glutathione peroxidase, and malondialdehyde, MDA). Serum samples were analyzed for cytokines. Jejunum tissue and colon content were collected and used for transcriptomic analyses and microbial characterization, respectively. Results indicated that there were greater (P < 0.05) MDA levels in the liver of pigs fed the diet with 250 mg/kg CuSO4 than in pigs fed the other diets. The serum concentration of tumor necrosis factor-alpha was greater (P < 0.05) in pigs fed diets containing CuSO4 compared with pigs fed the NC diet or the diet with 250 mg Cu/kg from Cu2O. Pigs fed diets containing CuSO4 or Cu2O had a greater (P < 0.05) abundance of genes related to the intestinal barrier function and nutrient transport, but a lower (P < 0.05) abundance of pro-inflammatory genes compared with pigs fed the NC diet. Supplementing diets with CuSO4 or Cu2O also increased (P < 0.05) the abundance of Lachnospiraceae and Peptostreptococcaceae families and reduced (P < 0.05) the abundance of the Rikenellaceae family, Campylobacter, and Streptococcus genera in the colon of pigs. In conclusion, adding 250 mg/kg of Cu from CuSO4 or Cu2O regulates genes abundance in charge of the immune system and growth, and promotes changes in the intestinal microbiota; however, Cu2O induces less systemic oxidation and inflammation compared with CuSO4.

Fibromodulin Ablation Exacerbates the Severity of Acute Colitis

Introduction

Epidemiological studies have associated pigment production with protection against certain human diseases. In contrast to African Americans, European descendants are more likely to suffer from angiogenesis-dependent and inflammatory diseases, such as wet age-related macular degeneration (ARMD) and ulcerative colitis (UC), respectively.

Methods

In a mouse model of dextran sulfate sodium (DSS)-induced acute colitis, the effect of fibromodulin (FMOD) depletion was examined on colitis severity.

Results

In this study, albino mice that produce high levels of FMOD developed less severe acute colitis compared with mice lacking in FMOD as assessed by clinical symptoms and histopathological changes. FMOD depletion affected the expression of tight junction proteins, contributing to the destruction of the epithelial barrier. Furthermore, this study revealed a stronger inflammatory response after DSS treatment in the absence of FMOD, where FMOD depletion led to an increase in activated T cells, plasmacytoid dendritic cells (pDCs), and type I interferon (IFN) production.

Discussion

These findings point to FMOD as a potential biomarker of disease severity in UC among light-skinned individuals of European descent.

Pattern Recognition Receptor Signaling and Cytokine Networks in Microbial Defenses and Regulation of Intestinal Barriers: Implications for Inflammatory Bowel Disease

Inflammatory bowel disease is characterized by defects in epithelial function and dysregulated inflammatory signaling by lamina propria mononuclear cells including macrophages and dendritic cells in response to microbiota. In this review, we focus on the role of pattern recognition receptors in the inflammatory response as well as epithelial barrier regulation. We explore cytokine networks that increase inflammation, regulate paracellular permeability, cause epithelial damage, up-regulate epithelial proliferation, and trigger restitutive processes. We focus on studies using patient samples as well as speculate on pathways that can be targeted to more holistically treat patients with inflammatory bowel disease.

Effects of Immobilized Antimicrobial Peptides on Growth Performance, Serum Biochemical Index, Inflammatory Factors, Intestinal Morphology, and Microbial Community in Weaning Pigs

This experiment was conducted to investigate the effects of immobilized antimicrobial peptides on growth performance, serum biochemical index, inflammatory factors, intestinal morphology, and microbial community of weaning piglets. A total of 21 weaning piglets [Duroc × (Landrace × Yorkshire)] with initial body weight (7.64 ± 0.65 kg) were randomly allocated to one of three treatments with seven replicates (one pig per replicate) per treatment according to sex and weight in randomized complete block design. Pigs in the three treatments were fed corn–soybean meal-based diet (CON), corn–soybean meal based diet + flavomycin (25 mg/kg) + quinone (50 mg/kg) (AB), and corn–soybean meal based diet + 1,000 mg/kg immobilized antimicrobial peptides (IAMPs), respectively. The experiment lasted for 28 days, including early stage (0–14 days) and late stage (15–28 days). The results showed the following: (1) compared with the CON group, the average daily gain in the whole experimental time (p < 0.05) was significantly increased, and the diarrhea rate of weaning piglets was decreased (p < 0.01) in the IAMPs group; (2) compared with the CON group, the concentrations of serum IgM and superoxide dismutase (SOD) in the IAMPs group were significantly higher than the CON and AB groups (p < 0.01); (3) compared with CON group, the concentrations of serum interleukin (IL)-10 and transforming growth factor (TGF-β) were significantly increased (p < 0.05), and the concentration of IL-12 was significantly decreased (p < 0.05) in the IAMPs group; (4) compared with CON group, the concentrations of serum endotoxin and D-lactate of piglets were significantly reduced (p < 0.05), and the relative expression of ZO-1 and occludin in the jejunum of piglets were significantly increased (p < 0.05) in the IAMPs group; (5) compared with the CON group, the villus height of the duodenum and jejunum of weaning piglets in IAMPs and AB groups was significantly increased (p < 0.05); and (6) compared with CON group, the relative abundance of Escherichia–Shigella in the colon and cecal digesta was decreased. In summary, the addition of 1,000 mg/kg immobilized antimicrobial peptides in the diet effectively relieved weaning stress by showing improved growth performance, antioxidant and immune capacity, intestinal morphology, and microorganisms.

Variations in the Composition of Human Milk Oligosaccharides Correlates with Effects on Both the Intestinal Epithelial Barrier and Host Inflammation: A Pilot Study

Background: Human milk oligosaccharides are complex, non-digestible carbohydrates that directly interact with intestinal epithelial cells to alter barrier function and host inflammation. Oligosaccharide composition varies widely between individual mothers, but it is unclear if this inter-individual variation has any impact on intestinal epithelial barrier function and gut inflammation. Methods: Human milk oligosaccharides were extracted from the mature human milk of four individual donors. Using an in vitro model of intestinal injury, the effects of the oligosaccharides on the intestinal epithelial barrier and select innate and adaptive immune functions were assessed. Results: Individual oligosaccharide compositions shared comparable effects on increasing transepithelial electrical resistance and reducing the macromolecular permeability of polarized (Caco-2Bbe1) monolayers but exerted distinct effects on the localization of the intercellular tight junction protein zona occludins-1 in response to injury induced by a human enteric bacterial pathogen Escherichia coli, serotype O157:H7. Immunoblots showed the differential effects of oligosaccharide compositions in reducing host chemokine interleukin 8 expression and inhibiting of p38 MAP kinase activation. Conclusions: These results provide evidence of both shared and distinct effects on the host intestinal epithelial function that are attributable to inter-individual differences in the composition of human milk oligosaccharides.

Challenges and opportunities targeting mechanisms of epithelial injury and recovery in acute intestinal graft-versus-host disease

Despite advances in immunosuppressive prophylaxis and overall supportive care, gastrointestinal (GI) graft-versus-host disease (GVHD) remains a major, lethal side effect after allogeneic hematopoietic stem cell transplantation (allo-HSCT). It has become increasingly clear that the intestinal epithelium, in addition to being a target of transplant-related toxicity and GVHD, plays an important role in the onset of GVHD. Over the last two decades, increased understanding of the epithelial constituents and their microenvironment has led to the development of novel prophylactic and therapeutic interventions, with the potential to protect the intestinal epithelium from GVHD-associated damage and promote its recovery following insult. In this review, we will discuss intestinal epithelial injury and the role of the intestinal epithelium in GVHD pathogenesis. In addition, we will highlight possible approaches to protect the GI tract from damage posttransplant and to stimulate epithelial regeneration, in order to promote intestinal recovery. Combined treatment modalities integrating immunomodulation, epithelial protection, and induction of regeneration may hold the key to unlocking mucosal recovery and optimizing therapy for acute intestinal GVHD.

Zearalenone Exposure Triggered Cecal Physical Barrier Injury through the TGF-β1/Smads Signaling Pathway in Weaned Piglets

This study aims to investigate the effects of exposure to different dosages of zearalenone (ZEA) on cecal physical barrier functions and its mechanisms based on the TGF-β1/Smads signaling pathway in weaned piglets. Thirty-two weaned piglets were allotted to four groups and fed a basal diet supplemented with ZEA at 0, 0.15, 1.5, and 3.0 mg/kg, respectively. The results showed that 1.5 and 3.0 mg/kg ZEA damaged cecum morphology and microvilli, and changed distribution and shape of M cells. Moreover, 1.5 and 3.0 mg/kg ZEA decreased numbers of goblet cells, the expressions of TFF3 and tight junction proteins, and inhibited the TGF-β1/Smads signaling pathway. Interestingly, the 0.15 mg/kg ZEA had no significant effect on cecal physical barrier functions but decreased the expressions of Smad3, p-Smad3 and Smad7. Our study suggests that high-dose ZEA exposure impairs cecal physical barrier functions through inhibiting the TGF-β1/Smads signaling pathway, but low-dose ZEA had no significant effect on cecum morphology and integrity through inhibiting the expression of smad7. These findings provide a scientific basis for helping people explore how to reduce the toxicity of ZEA in feeds.

Probiotic potential of commercial dairy-associated protective cultures: In vitro and in vivo protection against Listeria monocytogenes infection

Protective bacterial cultures (PCs) are commercially available to producers to control undesirable microbes in foods, including foodborne pathogens such as Listeria monocytogenes. They are generally recognized as safe for consumption and many are capable of producing bacteriocins. Yet their potential to act as probiotics and confer a health benefit on the host is not known. This study investigated the ability of three commercial PCs to survive human gastrointestinal conditions and exert anti-infective properties against L. monocytogenes. Counts of two PCs of Lactiplantibacillus plantarum remained unchanged after exposure to simulated gastrointestinal conditions, whereas counts of the PC Lactococcus lactis subsp. lactis were reduced by 5.3 log CFU/mL. Cultures of Lactiplantibacillus plantarum and Lactococcus lactis subsp. lactis adhered to human Caco-2 epithelial cells at ∼ 6 log CFU/mL. This pretreatment reduced subsequent L. monocytogenes adhesion and invasion by 1-1.6 log CFU/mL and 3.8-4.9 log CFU/mL, respectively, compared to control. L. monocytogenes-induced cytotoxicity was also reduced from 29.1% in untreated monolayers to ∼ 8% in those treated with PCs. Pretreatment of Caco-2 monolayers with Lactococcus lactis subsp. lactis and one PC of Lactiplantibacillus plantarum reduced L. monocytogenes translocation by ≥ 1.2 log CFU/mL compared to control (≥ 94.5% inhibition). All PCs significantly reduced Dextran^FITC permeability through Caco-2 monolayers to approximately half that of control. Pretreatment with PCs also reduced L. monocytogenes-induced mortality in Caenorhabditis elegans. These findings demonstrate the potential for commercially produced PCs to exert probiotic effects in the host through protection against L. monocytogenes infection, thus providing an additional benefit to food safety beyond inhibiting pathogen growth, survival, and virulence in foods.

Resveratrol protects intestinal integrity, alleviates intestinal inflammation and oxidative stress by modulating AhR/Nrf2 pathways in weaned piglets challenged with diquat

This study investigated the effects of resveratrol (RES) on intestinal morphology, antioxidant capacity, intestinal inflammation, and barrier function in weaned piglets challenged with diquat (DIQ). Thirty weaned piglets were randomly assigned to 5 treatments: non-challenged group (CON), DIQ-challenged group (DIQ), and DIQ-challenged group with 10, 30, or 90 mg/kg of RES, respectively. The trail lasted 21 days, and piglets were intraperitoneally injected with DIQ or the same amount of saline on day 15. The results showed that supplementation with 90 mg/kg RES increased (P < 0.05) jejunal villus height and villus height: crypt depth ratio, and decreased (P < 0.05) crypt depth, plasma D-lactate and diamine oxidase (DAO) compared with the DIQ group. Piglets fed with 30 or 90 mg/kg RES prevented the diquat-induced decrease (P < 0.05) of mRNA expression of occludin, claudin-1, ZO-1, and IL-10, and increase (P < 0.05) of TNF-α mRNA expression. Moreover, addition of 90 mg/kg RES increased (P < 0.05) the activities of SOD, GSH-Px, and CAT and decreased (P < 0.05) the MDA levels in jejunal mucosa compared with the DIQ group. Finally, addition of 90 mg/kg RES enhanced (P < 0.05) the mRNA expression of SOD1, SOD2, CAT, GPx1, and HO-1, and increased (P < 0.05) mRNA and protein expression of Nrf2, NQO1, aryl hydrocarbon receptor (AhR), and cytochrome P450 family 1 member A1 (CYP1A1). These data indicated that supplementation with 90 mg/kg RES was effective in protecting the intestinal integrity, alleviating intestinal inflammation and oxidative stress by activating AhR/Nrf2 pathways in diquat-challenged piglets.

Colon epithelial cell TGFβ signaling modulates the expression of tight junction proteins and barrier function in mice

Defective barrier function is a predisposing factor in inflammatory bowel disease (IBD) and colitis-associated cancer (CAC). Although TGFβ signaling defects have been associated with IBD and CAC, few studies have examined the relationship between TGFβ and intestinal barrier function. Here, we examine the role of TGFβ signaling via SMAD4 in modulation of colon barrier function. The Smad4 gene was conditionally deleted in the intestines of adult mice and intestinal permeability assessed using an in vivo 4 kDa FITC-Dextran (FD4) permeability assay. Mouse colon was isolated for gene expression (RNA-sequencing), Western blot, and immunofluorescence analysis. In vitro colon organoid culture was utilized to assess junction-related gene expression by qPCR and transepithelial resistance (TER). In silico analyses of human IBD and colon cancer databases were performed. Mice lacking intestinal expression of Smad4 demonstrate increased colonic permeability to FD4 without gross mucosal damage. mRNA/protein expression analyses demonstrate significant increases in Cldn2/Claudin 2 and Cldn8/Claudin 8, and decreases in Cldn3, Cldn4, and Cldn7/Claudin 7 with intestinal SMAD4 loss in vivo without changes in Claudin protein localization. TGFβ1/BMP2 treatment of polarized SMAD4+ colonoids increases TER. Cldn2, Cldn4, Cldn7, and Cldn8 are regulated by canonical TGFβ signaling, and TGFβ-dependent regulation of these genes is dependent on nascent RNA transcription (Cldn2, Cldn4, Cldn8) but not nascent protein translation (Cldn4, Cldn8). Human IBD/colon cancer specimens demonstrate decreased SMAD4, CLDN4, CLDN7, and CLDN8 and increased CLDN2 compared with healthy controls. Canonical TGFβ signaling modulates the expression of tight junction proteins and barrier function in mouse colon.NEW & NOTEWORTHY We demonstrate that canonical TGFβ family signaling modulates the expression of critical tight junction proteins in colon epithelial cells, and that expression of these tight junction proteins is associated with maintenance of colon epithelial barrier function in mice.

Chromogranin A regulates gut permeability via the antagonistic actions of its proteolytic peptides

AIM

A "leaky" gut barrier has been implicated in the initiation and progression of a multitude of diseases, for example, inflammatory bowel disease (IBD), irritable bowel syndrome and celiac disease. Here we show how pro-hormone Chromogranin A (CgA), produced by the enteroendocrine cells, and Catestatin (CST: hCgA_352-372 ), the most abundant CgA-derived proteolytic peptide, affect the gut barrier.

METHODS

Colon tissues from region-specific CST-knockout (CST-KO) mice, CgA-knockout (CgA-KO) and WT mice were analysed by immunohistochemistry, western blot, ultrastructural and flowcytometry studies. FITC-dextran assays were used to measure intestinal barrier function. Mice were supplemented with CST or CgA fragment pancreastatin (PST: CgA_250-301 ). The microbial composition of cecum was determined. CgA and CST levels were measured in blood of IBD patients.

RESULTS

Plasma levels of CST were elevated in IBD patients. CST-KO mice displayed (a) elongated tight, adherens junctions and desmosomes similar to IBD patients, (b) elevated expression of Claudin 2, and (c) gut inflammation. Plasma FITC-dextran measurements showed increased intestinal paracellular permeability in the CST-KO mice. This correlated with a higher ratio of Firmicutes to Bacteroidetes, a dysbiotic pattern commonly encountered in various diseases. Supplementation of CST-KO mice with recombinant CST restored paracellular permeability and reversed inflammation, whereas CgA-KO mice supplementation with CST and/or PST in CgA-KO mice showed that intestinal paracellular permeability is regulated by the antagonistic roles of these two peptides: CST reduces and PST increases permeability.

CONCLUSION

The pro-hormone CgA regulates the intestinal paracellular permeability. CST is both necessary and sufficient to reduce permeability and primarily acts by antagonizing PST.

Changes in bacterial community and expression of genes involved in intestinal innate immunity in the jejunum of newborn lambs during the first 24 hours of life

The newborn gut undergoes rapid colonization by commensal microorganisms and possible exposure to pathogens. The contribution of colostrum intake to host protection is well known; however, limited research exists on the intestinal innate immunity corresponding to colostrum intake during the passive immune transfer period in newborn ruminants. The aim of this study was to investigate the changes in bacterial community and expression of genes encoding toll-like receptors (TLR), mucins (MUC), antimicrobial peptides, and tight junctions in the jejunum of lambs that were fed colostrum during the first 24 h of life. Twenty-seven newborn lambs were used in this study, of which 18 lambs were bottle-fed pooled bovine colostrum within the first 2 h after birth to obtain an intake of approximately 8% of body weight. Lambs were slaughtered at 12 (n = 9) and 24 h (n = 9) after birth. The remaining 9 lambs without any feeding were slaughtered at 30 min after birth (0 h). Tissue and ligated segment samples from the jejunum were collected immediately after the lambs were slaughtered. The bacterial profile in the ligated jejunum segment was assessed using amplicon sequencing. The gene expression in the jejunum tissue was determined using quantitative real-time PCR. The relative abundances of Escherichia-Shigella, Lactobacillus, Lactococcus, and Streptococcus increased, whereas those of Sphingomonas, Phyllobacterium, Bradyrhizobium, and Rudaea decreased during the first 24 h of life. Expression of TLR2 and β-defensin 109-like was upregulated at 12 h after birth, but a recovery was detected at 24 h; TLR3, TLR5, LYZ, MUC1, MUC13, MUC20, and CLDN7 showed a higher expression level in samples taken at 24 h than in those taken at 0 h. In addition, expression level of CLDN1, CLDN4, and the junctional adhesion molecule-1 tended to be higher at 24 h than at 0 h after birth. Correlation analysis indicated that TLR2 expression was negatively correlated with the relative abundance of Lactobacillus and Bradyrhizobium, whereas TLR5 expression was positively correlated with the relative abundance of Escherichia-Shigella and Pelagibacterium. These results suggest that TLR, MUC, antimicrobial peptides, and CLDN act together and play an important role in intestinal defense during the passive immune transfer period. They are potentially associated with microbial colonization. The findings from this study provide novel information to elucidate the role of colostrum components in regulating the development of the intestinal mucosal immune barrier in newborn lambs during the passive immune transfer period.

The Effects of Dietary Porous Zinc Oxide Supplementation on Growth Performance, Inflammatory Cytokines and Tight Junction's Gene Expression in Early-Weaned Piglets

This study was conducted to investigate the effect of dietary porous ZnO supplementation on the growth performance, inflammatory cytokines and tight junction's gene expression in weaned piglets. A total of 192 weaned piglets were randomly allocated to 4 experimental groups (n=48/group) and fed, during 14 d, with one of the following dietary treatments: 1) basal diet (NC); 2) basal diet with 3,000 mg/kg of conventional ZnO (PC); 3) basal diet with 750 mg/kg of porous ZnO (low inclusion porous ZnO, LP-ZnO); 4) basal diet with 1,500 mg/kg porous ZnO (high inclusion porous ZnO, HP-ZnO). Results showed that dietary supplementation with regular ZnO or porous ZnO (750 and 1,500 mg/kg) improved average daily gain (ADG), feed to gain ratio (F/G) and jejunum morphology, while decreasing diarrhea incidence. Compared with the NC group, porous ZnO at both doses (750 or 1,500 mg/kg) increased serum alkaline phosphatase (ALP), immunoglobulin G (IgG) and insulin-like growth factor 1 (IGF-1) concentrations, but decreased serum glucose (GLU). Moreover, the mRNA expression of anti-inflammation cytokine (TGF-β), tight junction (Occludin, ZO-1) in the jejunum by different ZnO administration were significantly increased compared with the NC group, while mRNA expression of pro-inflammatory (IL-8), membrane channels that transport water (AQP3) and miR-122a were significantly decreased. It can be concluded that porous ZnO even at low dose (750 mg/kg) can be an effective alternative to pharmacological (3,000 mg/kg) conventional ZnO in reducing diarrhea, promoting the growth performance, increasing anti-inflammatory cytokines and tight junctions, reducing pro-inflammatory cytokines of weaned piglets.

Commercial whey products promote intestinal barrier function with glycomacropeptide enhanced activity in downregulating bacterial endotoxin lipopolysaccharides (LPS)-induced inflammation in vitro

Cheese whey contains bioactive compounds which have shown multiple health-promoting benefits. This study aimed to assess the commercial whey products (CWP) whey protein isolate (WPI), galacto-oligosaccharide-whey protein concentrate (GOS-W) and glycomacropeptide (GMP) for their potential to improve intestinal health in vitro using HT29-MTX intestinal goblet and Caco-2 epithelial cells. Results from HT29-MTX culture showed that WPI mitigated reactive oxygen species (ROS) production at a higher extent compared to GOS-W or GMP. However, GMP downregulated the lipopolysaccharide (LPS)-induced TLR-4 inflammatory pathway with the highest potency compared to the other CWP. Biomarkers of epithelial integrity assessed on both cell lines showed tight junction proteins claudin-1, claudin-3, occludin (OCC), and zonula occludens-1 (ZO-1) upregulation by GMP in HT29-MTX (1.33-1.93-fold of control) and in Caco-2 cells (1.56-2.09-fold of control). All CWP increased transepithelial electrical resistance (TEER) in TNF-α challenged Caco-2/HT29-MTX co-culture monolayer (p < 0.05), but only GMP was similar to the positive control TGF-β1, known for its role in promoting epithelial barrier function. The TNF-α-induced co-culture monolayer permeability was prevented at similar levels by all CWP (p < 0.05). In conclusion, CWP may be used as functional food ingredients to protect against intestinal disorders with emphasis on the GMP enhanced anti-inflammatory and intestinal barrier function properties. Further in vivo studies are guaranteed to validate these findings.

Loss of CD73 shifts transforming growth factor-β1 (TGF-β1) from tumor suppressor to promoter in endometrial cancer

In many tumors, CD73 (NT5E), a rate-limiting enzyme in adenosine biosynthesis, is upregulated by TGF-β and drives tumor progression. Conversely, CD73 is downregulated in endometrial carcinomas (EC) despite a TGF-β-rich environment. Through gene expression analyses of normal endometrium samples of the uterine cancer TCGA data set and genetic and pharmacological studies, we discovered CD73 loss shifts TGF-β1 from tumor suppressor to promoter in EC. TGF-β1 upregulated CD73 and epithelial integrity in vivo in the normal endometrium and in vitro in early stage EC cells. With loss of CD73, TGF-β1-mediated epithelial integrity was abrogated. EC cells developed TGF-β1-mediated stress fibers and macromolecule permeability, migration, and invasion increased. In human tumors, CD73 is downregulated in deeply invasive stage I EC. Consistent with shifting TGF-β1 activity, CD73 loss increased TGF-β1-mediated canonical signaling and upregulated cyclin D1 (CCND1) and downregulated p21 expression. This shift was clinically relevant, as CD73^Low/CCND1^High expression associated with poor tumor differentiation, increased myometrial and lymphatic/vascular space invasion, and patient death. Further loss of CD73 in CD73^Low expressing advanced stage EC cells increased TGF-β-mediated stress fibers, signaling, and invasiveness, whereby adenosine A1 receptor agonist, CPA, dampened TGF-β-mediated invasion. These data identify CD73 loss as essential for shifting TGF-β activity in EC.

Skin damage caused by scale loss modifies the intestine of chronically stressed gilthead sea bream (Sparus aurata, L.)

The present study was designed to test if the damage caused by scale loss provokes a change in other innate immune barriers such as the intestine and how chronic stress affects this response. Sea bream (Sparus aurata) were kept in tanks at low density (16 kg m^-3, LD) or exposed to a chronic high density (45 kg m^-3, HD) stress for 4 weeks. Scales were then removed (approximately 50%) from the left flank in the LD and HD fish. Intestine samples (n = 8/group) were examined before and at 12 h, 3 days and 7 days after scale removal. Changes in the morphology of the intestine revealed that chronic stress and scale loss was associated with intestinal inflammation. Specifically, enterocyte height and the width of the lamina propria, submucosa and muscle layer were significantly increased (p < 0.05) 3 days after skin damage in fish under chronic stress (HD) compared to other treatments (LDWgut3d or HDgut0h). This was associated with a significant up-regulation (p < 0.05) in the intestine of gene transcripts for cell proliferation (pcna) and anti-inflammatory cytokine tgfβ1 and down-regulation of gene transcripts for the pro-inflammatory cytokines tnf-α and il1β (p < 0.05) in HD and LD fish 3 days after scale removal compared to the undamaged control (LDgut0h). Furthermore, a significant up-regulation of kit, a marker of mast cells, in the intestine of HDWgut3d and LDWgut3d fish suggests they may mediate the crosstalk between immune barriers. Skin damage induced an increase in cortisol levels in the anterior intestine in HDWgut12 h fish and significant (p < 0.05) down-regulation of mr expression, irrespective of stress. These results suggest glucocorticoid levels and signalling in the intestine of fish are modified by superficial cutaneous wounds and it likely modulates intestine inflammation.

Association of differentially expressed genes and autoantibody type in patients with systemic sclerosis

OBJECTIVES

The aims of this study were to investigate the relationship between the type of autoantibody and gene expression profile in skin lesions from patients with SSc, and to identify specific dysregulated pathways in SSc patients compared with healthy controls.

METHODS

Sixty-one patients with SSc from the Genetics vs Environment in Scleroderma Outcome Study cohort and 36 healthy controls were included in this study. Differentially expressed genes were extracted and functional enrichment and pathway analysis were conducted.

RESULTS

Compared with healthy controls, lists containing 2, 71, 10, 144 and 78 differentially expressed genes were created for patients without specific autoantibody, ACA, anti-U1 RNP antibody (RNP), anti-RNA polymerase III antibody (RNAP) and anti-topoisomerase I antibody (ATA), respectively. While part of the enriched pathways overlapped, distinct pathways were identified except in those patients lacking specific autoantibody. The distinct enriched pathways included 'keratinocyte differentiation' for ACA, 'nuclear factor κB signalling' and 'cellular response to TGF-β stimulus' for RNAP, 'interferon α/β signalling' for RNP, and 'cellular response to stress' for ATA. Cell type signature score analysis revealed that macrophages/monocytes, endothelial cells and fibroblasts were associated with ACA, RNAP, ATA and the severity of the SSc skin lesions.

CONCLUSION

Pathogenic pathways were identified according to the type of autoantibody by leveraging gene expression data of patients and controls from a multicentre cohort. The current study may promote the search for new therapeutic targets for SSc.

Partners in Leaky Gut Syndrome: Intestinal Dysbiosis and Autoimmunity

The intestinal surface is constitutively exposed to diverse antigens, such as food antigens, food-borne pathogens, and commensal microbes. Intestinal epithelial cells have developed unique barrier functions that prevent the translocation of potentially hostile antigens into the body. Disruption of the epithelial barrier increases intestinal permeability, resulting in leaky gut syndrome (LGS). Clinical reports have suggested that LGS contributes to autoimmune diseases such as type 1 diabetes, multiple sclerosis, rheumatoid arthritis, and celiac disease. Furthermore, the gut commensal microbiota plays a critical role in regulating host immunity; abnormalities of the microbial community, known as dysbiosis, are observed in patients with autoimmune diseases. However, the pathological links among intestinal dysbiosis, LGS, and autoimmune diseases have not been fully elucidated. This review discusses the current understanding of how commensal microbiota contributes to the pathogenesis of autoimmune diseases by modifying the epithelial barrier.

Partners in Leaky Gut Syndrome: Intestinal Dysbiosis and Autoimmunity

The intestinal surface is constitutively exposed to diverse antigens, such as food antigens, food-borne pathogens, and commensal microbes. Intestinal epithelial cells have developed unique barrier functions that prevent the translocation of potentially hostile antigens into the body. Disruption of the epithelial barrier increases intestinal permeability, resulting in leaky gut syndrome (LGS). Clinical reports have suggested that LGS contributes to autoimmune diseases such as type 1 diabetes, multiple sclerosis, rheumatoid arthritis, and celiac disease. Furthermore, the gut commensal microbiota plays a critical role in regulating host immunity; abnormalities of the microbial community, known as dysbiosis, are observed in patients with autoimmune diseases. However, the pathological links among intestinal dysbiosis, LGS, and autoimmune diseases have not been fully elucidated. This review discusses the current understanding of how commensal microbiota contributes to the pathogenesis of autoimmune diseases by modifying the epithelial barrier.

Involvement of Smad7 in Inflammatory Diseases of the Gut and Colon Cancer

In physiological conditions, the human intestinal mucosa is massively infiltrated with various subsets of immune cells, the activity of which is tightly regulated by several counter-regulatory factors. One of these factors is transforming growth factor-β1 (TGF-β1), a cytokine produced by multiple cell types and targeting virtually all the intestinal mucosal cells. Binding of TGF-β1 to its receptors triggers Smad2/3 signaling, thus culminating in the attenuation/suppression of immune–inflammatory responses. In patients with Crohn’s disease and patients with ulcerative colitis, the major human inflammatory bowel diseases (IBD), and in mice with IBD-like colitis, there is defective TGF-β1/Smad signaling due to high levels of the intracellular inhibitor Smad7. Pharmacological inhibition of Smad7 restores TGF-β1 function, thereby reducing inflammatory pathways in patients with IBD and colitic mice. On the other hand, transgenic over-expression of Smad7 in T cells exacerbates colitis in various mouse models of IBD. Smad7 is also over-expressed in other inflammatory disorders of the gut, such as refractory celiac disease, necrotizing enterocolitis and cytomegalovirus-induced colitis, even though evidence is still scarce and mainly descriptive. Furthermore, Smad7 has been involved in colon carcinogenesis through complex and heterogeneous mechanisms, and Smad7 polymorphisms could influence cancer prognosis. In this article, we review the data about the expression and role of Smad7 in intestinal inflammation and cancer.

Weaning causes a prolonged but transient change in immune gene expression in the intestine of piglets

Controlling gut inflammation is important in managing gut disorders in the piglet after weaning. Establishing patterns of inflammation markers in the time subsequent to weaning is important for future research to determine whether interventions are effective in controlling gut inflammation. The objective of this study was to evaluate the intestinal inflammatory response during the postweaning period in piglets. A 45-d study included 108 piglets (weaned at 22 d, body weight 5.53 ± 1.19 kg), distributed in 12 pens with nine pigs per pen. Histomorphometry, gene expression of pro- and anti-inflammatory cytokines, and the quantity of immunoglobulin (Ig) A producing cells were measured in jejunum, ileum, and colon on days 0, 15, 30, and 45 postweaning. Cytokine gene expression in peripheral blood mononuclear cells and Ig quantities were analyzed in blood from piglets on days 0, 15, 30, and 45 postweaning. Histomorphometrical results showed a lower villus length directly after weaning. Results demonstrated a postweaning intestinal inflammation response for at least 15 d postweaning by upregulation of IgA producing cells and IFN-γ, IL-1α, IL-8, IL-10, IL-12α, and TGF-β in jejunum, ileum, and colon. IgM and IgA were upregulated at day 30 postweaning. IgG was downregulated at day 15 postweaning. The results indicate that weaning in piglets is associated with a prolonged and transient response in gene expression of pro- and anti-inflammatory cytokines and IgA producing cells in the intestine.

Antiviral Properties of Human Milk

Humans have always coexisted with viruses, with both positive and negative consequences. Evolutionary pressure on mammals has selected intrinsic properties of lactation and milk to support the relatively immunocompromised neonate from environmental pathogens, as well as support the normal development of diverse immune responses. Human milk supports both adaptive and innate immunity, with specific constituents that drive immune learning and maturation, and direct protection against microorganisms. Viruses constitute one of the most ancient pressures on human evolution, and yet there is a lack of awareness by both public and healthcare professionals of the complexity of human milk as an adaptive response beyond the production of maternal antibodies. This review identifies and describes the specific antiviral properties of human milk and describes how maternal support of infants through lactation is protective beyond antibodies.

Qualitative Nitrogen Malnutrition Damages Gut and Alters Microbiome in Adult Mice. A Preliminary Histopathological Study

Amino-acids (AAs) are the exclusive source of nitrogen for cells. AAs result from the breakdown of food proteins and are absorbed by mucosa of the small intestine that act as a barrier to harmful materials. The quality of food proteins may differ, since it reflects content in Essential-AAs (EAAs) and digestibility but, until now, attention was paid mainly to the interaction between indigested proteins as a whole and microbiota. The link between microbiome and quality of proteins has been poorly studied, although these metabolic interactions are becoming more significant in different illnesses. We studied the effects of a special diet containing unbalanced EAAs/Non-EAAs ratio, providing excess of Non-EAAs, on the histopathology of gut epithelium and on the microbiome in adult mice, as model of qualitative malnutrition. Excess in Non-EAAs have unfavorable quick effect on body weight, gut cells, and microbiome, promoting weakening of the intestinal barrier. Re-feeding these animals with standard diet partially reversed the body alterations. The results prove that an unbalanced EAAs/Non-EAAs ratio is primarily responsible for microbiome modifications, not vice-versa. Therefore, treating microbiota independently by treating co-existing qualitative malnutrition does not make sense. This study also provides a reproducible model of sarcopenia-wasting cachexia like the human protein malnutrition.

Molecular Dambusters: What Is Behind Hyperpermeability in Bradykinin-Mediated Angioedema?

In the last few decades, a substantial body of evidence underlined the pivotal role of bradykinin in certain types of angioedema. The formation and breakdown of bradykinin has been studied thoroughly; however, numerous questions remained open regarding the triggering, course, and termination of angioedema attacks. Recently, it became clear that vascular endothelial cells have an integrative role in the regulation of vessel permeability. Apart from bradykinin, a great number of factors of different origin, structure, and mechanism of action are capable of modifying the integrity of vascular endothelium, and thus, may participate in the regulation of angioedema formation. Our aim in this review is to describe the most important permeability factors and the molecular mechanisms how they act on endothelial cells. Based on endothelial cell function, we also attempt to explain some of the challenging findings regarding bradykinin-mediated angioedema, where the function of bradykinin itself cannot account for the pathophysiology. By deciphering the complex scenario of vascular permeability regulation and edema formation, we may gain better scientific tools to be able to predict and treat not only bradykinin-mediated but other types of angioedema as well.

Cell Type-Specific Decomposition of Gingival Tissue Transcriptomes

Genome-wide transcriptomic analyses in whole tissues reflect the aggregate gene expression in heterogeneous cell populations comprising resident and migratory cells, and they are unable to identify cell type-specific information. We used a computational method (population-specific expression analysis [PSEA]) to decompose gene expression in gingival tissues into cell type-specific signatures for 8 cell types (epithelial cells, fibroblasts, endothelial cells, neutrophils, monocytes/macrophages, plasma cells, T cells, and B cells). We used a gene expression data set generated using microarrays from 120 persons (310 tissue samples; 241 periodontitis affected and 69 healthy). Decomposition of the whole-tissue transcriptomes identified differentially expressed genes in each of the cell types, which mapped to biologically relevant pathways, including dysregulation of Th17 cell differentiation, AGE-RAGE signaling, and epithelial-mesenchymal transition in epithelial cells. We validated selected PSEA-predicted, differentially expressed genes in purified gingival epithelial cells and B cells from an unrelated cohort (n = 15 persons), each of whom contributed with 1 periodontitis-affected and 1 healthy gingival tissue sample. Differential expression of these genes by quantitative reverse transcription polymerase chain reaction corroborated the PSEA predictions and pointed to dysregulation of biologically important pathways in periodontitis. Collectively, our results demonstrate the robustness of the PSEA in the decomposition of gingival tissue transcriptomes and its ability to identify differentially regulated transcripts in particular cellular constituents. These genes may serve as candidates for further investigation with respect to their roles in the pathogenesis of periodontitis.

Interplay Between Microbiota, Toll-Like Receptors and Cytokines for the Maintenance of Epithelial Barrier Integrity

The intestinal tract is densely populated by microbiota consisting of various commensal microorganisms that are instrumental for the healthy state of the living organism. Such commensals generate various molecules that can be recognized by the Toll-like receptors of the immune system leading to the inflammation marked by strong upregulation of various proinflammatory cytokines, such as TNF, IL-6, and IL-1β. To prevent excessive inflammation, a single layer of constantly renewing, highly proliferating epithelial cells (IEC) provides proper segregation of such microorganisms from the body cavities. There are various triggers which facilitate the disturbance of the epithelial barrier which often leads to inflammation. However, the nature and duration of the stress may determine the state of the epithelial cells and their responses to cytokines. Here we discuss the role of the microbiota-TLR-cytokine axis in the maintenance of the epithelial tissue integrity. In particular, we highlight discrepancies in the function of TLR and cytokines in IEC barrier during acute or chronic inflammation and we suggest that intervention strategies should be applied based on the type of inflammation.

Role of TGF-Beta and Smad7 in Gut Inflammation, Fibrosis and Cancer

The human gastrointestinal tract contains the largest population of immune cells in the body and this is a reflection of the fact that it is continuously exposed to a myriad of dietary and bacterial antigens. Although these cells produce a variety of inflammatory cytokines that could potentially promote tissue damage, in normal conditions the mucosal immune response is tightly controlled by counter-regulatory factors, which help induce and maintain gut homeostasis and tolerance. One such factor is transforming growth factor (TGF)-β1, a cytokine produced by multiple lineages of leukocytes, stromal cells and epithelial cells, and virtually targets all the gut mucosal cell types. Indeed, studies in animals and humans have shown that defects in TGF-β1 production and/or signaling can lead to the development of immune-inflammatory pathologies, fibrosis and cancer in the gut. Here, we review and discuss the available evidence about the role of TGF-β1 and Smad7, an inhibitor of TGF-β1 activity, in gut inflammation, fibrosis and cancer with particular regard to the contribution of these two molecules in the pathogenesis of inflammatory bowel diseases and colon cancer.

Gut Microbiota-Bile Acid Crosstalk in Diarrhea-Irritable Bowel Syndrome

The occurrence of diarrhea-predominant irritable bowel syndrome (IBS-D) is the result of multiple factors, and its pathogenesis has not yet been clarified. Emerging evidence indicates abnormal changes in gut microbiota and bile acid (BA) metabolism have a close relationship with IBS-D. Gut microbiota is involved in the secondary BA production via deconjugation, 7α-dehydroxylation, oxidation, epimerization, desulfation, and esterification reactions respectively. Changes in the composition and quantity of gut microbiota have an important impact on the metabolism of BAs, which can lead to the occurrence of gastrointestinal diseases. BAs, synthesized in the hepatocytes, play an important role in maintaining the homeostasis of gut microbiota and the balance of glucose and lipid metabolism. In consideration of the complex biological functional connections among gut microbiota, BAs, and IBS-D, it is urgent to review the latest research progress in this field. In this review, we summarized the alterations of gut microbiota in IBS-D and discussed the mechanistic connections between gut microbiota and BA metabolism in IBS-D, which may be involved in activating two important bile acid receptors, G-protein coupled bile acid receptor 1 (TGR5) and farnesoid X receptor (FXR). We also highlight the strategies of prevention and treatment of IBS-D via regulating gut microbiota-bile acid axis, including probiotics, fecal microbiota transplantation (FMT), cholestyramine, and the cutting-edge technology about bacteria genetic engineering.