Trefoil family factor 2 is expressed in murine gastric and immune cells and controls both gastrointestinal inflammation and systemic immune responses

An active protein from Dendrobium officinale residue: Protects the gastric mucosa and stabilized in the gastrointestinal tract

A large number of by-products generated in the food industry is discarded as waste, especially the residue left after extracting plant resources, which is typically repurposed as fertilizer. In this study, we extracted and purified a new protein, DOP1, from the residue of Dendrobium officinale Kimura & Migo (D. officinale), and explored the protective effect of DOP1 on alcohol-induced gastric mucosal injury. Its amino acid composition and the stability of secondary structure were measured by amino acid analysis and various spectroscopic methods. The microscopic morphology of DOP1 was observed by electron microscopy and its particle distribution was determined to be in the range of 3.7-5.5 nm. In addition, DOP1 was found to exhibit excellent protective activity against alcohol-induced gastric mucosal injury, as well as anti-inflammatory and antioxidant activities by in vitro and in vivo activity assays, which may be related to the upregulation of TFF2 through the activation of PPARγ. Intriguingly, DOP1 does not degrade and remains active after being digested by the gastrointestinal tract. From an economic and sustainable perspective, the discovery of DOP1 will provide new opportunities for the enhanced utilization and sustainable development of D. officinale resources.

Role of trefoil factors in maintaining gut health in food animals

It is imperative to preserve the integrity of the gastrointestinal system in spite of the persistent existence of harmful chemicals and microbial flora in the gut. This is made possible by essential healing initiators called Trefoil factors which helps in mucosal reconstitution and tissue development on the gastrointestinal surface. The trefoil factors are a class of abundant secreted proteins that are essential for epithelial continuity (TFFs). Trefoil factor family (TFF) proteins are biologically active peptides that play significant role in safeguarding, restoring and continuity of the gastrointestinal tract (GIT) epithelium, through collaborative modulations with mucins in the mucosal layer. These peptides are readily produced in reaction to epithelial damage in the digestive tract, thereby contributing to the healing and restituting of the epithelial layers of the intestine. In addition, considerable evidence indicated that TFF peptides trigger proliferation, migration and angiogenesis, all which are crucial processes for wound healing. There is also increasing evidence that TFF peptides modulate the mucosal immune system. These protective properties, suggest that dietary manipulation strategies targeted at enhancing the expression and synthesis of TFF peptides at optimal levels in the GIT epithelium, may constitute a plausible alternative strategy to the use of in-feed antibiotic growth promoters to maintain epithelial integrity and promote resistance to enteric pathogens. This review describes TFF peptides, with importance to their biological functions and involvement in gastrointestinal mucosal protection and repair in food animals.

Trefoil Factor 2 Expressed by the Murine Pancreatic Acinar Cells Is Required for the Development of Islets and for β-Cell Function During Aging

Exocrine-to-endocrine cross talk in the pancreas is crucial to maintain β-cell function. However, the molecular mechanisms underlying this cross talk are largely undefined. Trefoil factor 2 (Tff2) is a secreted factor known to promote the proliferation of β-cells in vitro, but its physiological role in vivo in the pancreas is unknown. Also, it remains unclear which pancreatic cell type expresses Tff2 protein. We therefore created a mouse model with a conditional knockout of Tff2 in the murine pancreas. We find that the Tff2 protein is preferentially expressed in acinar but not ductal or endocrine cells. Tff2 deficiency in the pancreas reduces β-cell mass on embryonic day 16.5. However, homozygous mutant mice are born without a reduction of β-cells and with acinar Tff3 compensation by day 7. When mice are aged to 1 year, both male and female homozygous and male heterozygous mutants develop impaired glucose tolerance without affected insulin sensitivity. Perifusion analysis reveals that the second phase of glucose-stimulated insulin secretion from islets is reduced in aged homozygous mutant compared with controls. Collectively, these results demonstrate a previously unknown role of Tff2 as an exocrine acinar cell-derived protein required for maintaining functional endocrine β-cells in mice.

ARTICLE HIGHLIGHTS

Single-cell view into the role of microbiota shaping host immunity in the larynx

Microbiota play a critical role in the development and training of host innate and adaptive immunity. We present the cellular landscape of the upper airway, specifically the larynx, by establishing a reference single-cell atlas, while dissecting the role of microbiota in cell development and function at single-cell resolution. We highlight the larynx's cellular heterogeneity with the identification of 16 cell types and 34 distinct subclusters. Our data demonstrate that commensal microbiota have extensive impact on the laryngeal immune system by regulating cell differentiation, increasing the expression of genes associated with host defense, and altering gene regulatory networks. We uncover macrophages, innate lymphoid cells, and multiple secretory epithelial cells, whose cell proportions and expressions vary with microbial exposure. These cell types play pivotal roles in maintaining laryngeal and upper airway health and provide specific guidance into understanding the mechanism of immune system regulation by microbiota in laryngeal health and disease.

Expression Profiling along the Murine Intestine: Different Mucosal Protection Systems and Alterations in Tff1-Deficient Animals

Tff1 is a typical gastric peptide secreted together with the mucin, Muc5ac. Tff1-deficient (Tff1KO) mice are well known for their prominent gastric phenotype and represent a recognized model for antral tumorigenesis. Notably, intestinal abnormalities have also been reported in the past in these animals. Here, we have compared the expression of selected genes in Tff1KO mice and their corresponding wild-type littermates (RT-PCR analyses), focusing on different mucosal protection systems along the murine intestine. As hallmarks, genes were identified with maximum expression in the proximal colon and/or the duodenum: Agr2, Muc6/A4gnt/Tff2, Tff1, Fut2, Gkn2, Gkn3, Duox2/Lpo, Nox1. This is indicative of different protection systems such as Tff2/Muc6, Tff1-Fcgbp, gastrokines, fucosylation, and reactive oxygen species (ROS) in the proximal colon and/or duodenum. Few significant transcriptional changes were observed in the intestine of Tff1KO mice when compared with wild-type littermates, Clca1 (Gob5), Gkn1, Gkn2, Nox1, Tff2. We also analyzed the expression of Tff1, Tff2, and Tff3 in the pancreas, liver, and lung of Tff1KO and wild-type animals, indicating a cross-regulation of Tff gene expression. Furthermore, on the protein level, heteromeric Tff1-Fcgbp and various monomeric Tff1 forms were identified in the duodenum and a high-molecular-mass Tff2/Muc6 complex was identified in the proximal colon (FPLC, proteomics).

The Forms of the Lectin Tff2 Differ in the Murine Stomach and Pancreas: Indications for Different Molecular Functions

The lectin TFF2 belongs to the trefoil factor family (TFF). This polypeptide is typically co-secreted with the mucin MUC6 from gastric mucous neck cells, antral gland cells, and duodenal Brunner glands. Here, TFF2 fulfills a protective function by forming a high-molecular-mass complex with the MUC6, physically stabilizing the mucus barrier. In pigs and mice, and slightly in humans, TFF2 is also synthesized in the pancreas. Here, we investigated the murine stomach, pancreas, and duodenum by fast protein liquid chromatography (FPLC) and proteomics and identified different forms of Tff2. In both the stomach and duodenum, the predominant form is a high-molecular-mass complex with Muc6, whereas, in the pancreas, only low-molecular-mass monomeric Tff2 was detectable. We also investigated the expression of Tff2 and other selected genes in the stomach, pancreas, and the proximal, medial, and distal duodenum (RT-PCR analysis). The absence of the Tff2/Muc6 complex in the pancreas is due to a lack of Muc6. Based on its known motogenic, anti-apoptotic, and anti-inflammatory effects, we propose a protective receptor-mediated function of monomeric Tff2 for the pancreatic ductal epithelium. This view is supported by a report that a loss of Tff2 promotes the formation of pancreatic intraductal mucinous neoplasms.

Electroacupuncture Zusanli (ST36) Relieves Somatic Pain in Colitis Rats by Inhibiting Dorsal Root Ganglion Sympathetic-Sensory Coupling and Neurogenic Inflammation

Referred somatic pain triggered by hyperalgesia is common in patients with inflammatory bowel disease (IBD). It was reported that sprouting of sympathetic nerve fibers into the dorsal root ganglion (DGR) and neurogenic inflammation were related to neuropathic pain, the excitability of neurons, and afferents. The purpose of the study was to explore the potential and mechanism of electroacupuncture (EA) at Zusanli (ST36) for the intervention of colon inflammation and hyperalgesia. Sprague-Dawley (SD) was randomly divided into four groups, including control, model, EA, and sham-EA. Our results showed EA treatment significantly attenuated dextran sulfate sodium- (DSS-) induced colorectal lesions and inflammatory cytokine secretion, such as TNF-α, IL-1β, PGE2, and IL-6. EA also inhibited mechanical and thermal pain hypersensitivities of colitis rats. Importantly, EA effectively abrogated the promotion effect of DSS on ipsilateral lumbar 6 (L6) DRG sympathetic-sensory coupling, manifested as the sprouting of tyrosine hydroxylase- (TH-) positive sympathetic fibers into sensory neurons and colocalization of and calcitonin gene-related peptide (CGRP). Furthermore, EA at Zusanli (ST36) activated neurogenic inflammation, characterized by decreased expression of substance P (SP), hyaluronic acid (HA), bradykinin (BK), and prostacyclin (PGI2) in colitis rat skin tissues corresponding to the L6 DRG. Mechanically, EA treatment reduced the activation of the TRPV1/CGRP, ERK, and TLR4 signaling pathways in L6 DRG of colitis rats. Taken together, we presumed that EA treatment improved colon inflammation and hyperalgesia, potentially by suppressing the sprouting of sympathetic nerve fibers into the L6 DGR and neurogenic inflammation via deactivating the TRPV1/CGRP, ERK, and TLR4 signaling pathways.

Self-Renewal and Cancers of the Gastric Epithelium: An Update and the Role of the Lectin TFF1 as an Antral Tumor Suppressor

In 2020, gastric cancer was the fourth leading cause of cancer deaths globally. About 90% of gastric cancers are sporadic and the vast majority are correlated with Helicobacter pylori infection; whereas familial clustering is observed in about 10% of cases. Gastric cancer is now considered to be a disease originating from dysregulated self-renewal of the gastric glands in the setting of an inflammatory environment. The human stomach contains two types of gastric units, which show bi-directional self-renewal from a complex variety of stem cells. This review focuses on recent progress concerning the characterization of the different stem cell populations and the mainly mesenchymal signals triggering their stepwise differentiation as well as the genesis of pre-cancerous lesions and carcinogenesis. Furthermore, a model is presented (Lectin-triggered Receptor Blocking Hypothesis) explaining the role of the lectin TFF1 as an antral tumor suppressor possibly regulating Lgr5⁺ antral stem cells in a paracrine or maybe autocrine fashion, with neighboring antral gland cells having a role as niche cells.

Diet Impact on Obesity beyond Calories and Trefoil Factor Family 2 (TFF2) as an Illustration: Metabolic Implications and Potential Applications

Obesity is a health problem with increasing impacts on public health, economy and even social life. In order to reestablish the energy balance, obesity management focuses mainly on two pillars; exercise and diet. Beyond the contribution to the caloric intake, the diet nutrients and composition govern a variety of properties. This includes the energy balance-independent properties and the indirect metabolic effects. Whereas the energy balance-independent properties are close to "pharmacological" effects and include effects such as antioxidant and anti-inflammatory, the indirect metabolic effects represent the contribution a diet can have on energy metabolism beyond the caloric contribution itself, which include the food intake control and metabolic changes. As an illustration, we also described the metabolic implication and hypothetical pathways of the high-fat diet-induced gene Trefoil Factor Family 2. The properties the diet has can have a variety of applications mainly in pharmacology and nutrition and further explore the "pharmacologically" active food towards potential therapeutic applications.

Trefoil factor family 2 inhibits cholangiocarcinogenesis by regulating the PTEN pathway in mice

Trefoil factor family 2 (TFF2) is one of three trefoil factor family proteins and is expressed abundantly in the gastrointestinal epithelium. Recent studies have shown that TFF2 acts as a tumor suppressor in gastric and pancreatic carcinogenesis; however, little is known about its function in cholangiocarcinogenesis. To investigate the function of TFF2 in cholangiocellular carcinoma (CCC), immunohistochemistry of surgically resected human CCC samples was performed. TFF2 expression was upregulated in the early stage and lost in the late stage of cholangiocarcinogenesis, suggesting the association of TFF2 and CCC. A TFF2 expression vector was then transfected into a CCC cell line (HuCCT1) in vitro, revealing that TFF2 functions as a tumor suppressor not only by inhibiting proliferation and invasion but also by promoting the apoptosis of cancer cells. In addition, PTEN signaling activity was downregulated by TFF2, suggesting an association between TFF2 and PTEN. Next, hepatic carcinogenesis model mice (KC; albumin-Cre/Lox-Stop-Lox KRAS G12D) were bred with TFF2-knockout mice to generate a TFF2-deficient mouse model (KC/TFF2 -/-). Although the incidence of hepatocellular carcinoma was not different between KC/TFF2 -/- mice and control mice, biliary intraepithelial neoplasm (BilIN), the precursor of CCC, was frequently found in the biliary epithelium of KC/TFF2 -/- mice. Immunohistochemistry revealed that BilIN samples from these mice did not express PTEN. In addition, two KC/TFF2 -/- mice developed CCC adjacent to BilIN, suggesting that TFF2 functions to inhibit the development of CCC in vivo. These results indicate that TFF2 acts as a tumor suppressor to inhibit the development of CCC by regulating PTEN activity.

Trefoil Factor Family Member 2: From a High-Fat-Induced Gene to a Potential Obesity Therapy Target

Obesity has its epidemiological patterns continuously increasing. With controlling both diet and exercise being the main approaches to manage the energy metabolism balance, a high-fat (HF) diet is of particular importance. Indeed, lipids have a low satiety potential but a high caloric density. Thus, focusing on pharmacologically targetable pathways remains an approach with promising therapeutic potential. Within this context, trefoil factor family member 2 (Tff2) has been characterized as specifically induced by HF diet rather than low-fat diet. TFF2 has also been linked to diverse neurological mechanisms and metabolic patterns suggesting its role in energy balance. The hypothesis is that TFF2 would be a HF diet-induced signal that regulates metabolism with a focus on lipids. Within this review, we put the spotlight on key findings highlighting this line of thought. Importantly, the hypothetical mechanisms pointed highlight TFF2 as an important contributor to obesity development via increasing lipids intestinal absorption and anabolism. Therefore, an outlook for future experimental activities and evaluation of the therapeutic potential of TFF2 inhibition is given. Indeed, its knockdown or downregulation would contribute to an antiobesity phenotype. We believe this work represents an addition to our understanding of the lipidic molecular implications in obesity, which will contribute to develop therapies aiming to manage the lipidic metabolic pathways including the absorption, storage and metabolism via targeting TFF2-related pathways. We briefly discuss important relevant concepts for both basic and clinical researchers.

Trefoil Factor Family (TFF) Peptides and Their Links to Inflammation: A Re-evaluation and New Medical Perspectives

Trefoil factor family peptides (TFF1, TFF2, TFF3), together with mucins, are typical exocrine products of mucous epithelia. Here, they act as a gastric tumor suppressor (TFF1) or they play different roles in mucosal innate immune defense (TFF2, TFF3). Minute amounts are also secreted as endocrine, e.g., by the immune and central nervous systems. As a hallmark, TFF peptides have different lectin activities, best characterized for TFF2, but also TFF1. Pathologically, ectopic expression occurs during inflammation and in various tumors. In this review, the role of TFF peptides during inflammation is discussed on two levels. On the one hand, the expression of TFF1-3 is regulated by inflammatory signals in different ways (upstream links). On the other hand, TFF peptides influence inflammatory processes (downstream links). The latter are recognized best in various Tff-deficient mice, which have completely different phenotypes. In particular, TFF2 is secreted by myeloid cells (e.g., macrophages) and lymphocytes (e.g., memory T cells), where it modulates immune reactions triggering inflammation. As a new concept, in addition to lectin-triggered activation, a hypothetical lectin-triggered inhibition of glycosylated transmembrane receptors by TFF peptides is discussed. Thus, TFFs are promising players in the field of glycoimmunology, such as galectins and C-type lectins.

High-Fat Diet-Induced Trefoil Factor Family Member 2 (TFF2) to Counteract the Immune-Mediated Damage in Mice

Simple Summary

High-fat (HF) diet induces both immune-mediated damage and trefoil factor family member 2 (Tff2) expression. As TFF2 has tissue repair and protection properties, this suggests that HF diet-induced Tff2 production and the resulting TFF2 mucosal protective effects would be a mechanism to counteract the HF diet-induced tissue damage. On the other hand, the induction of Tff2 by HF diet could indicate that TFF2 is a food intake regulator (appetite control) since Tff2 is also expressed in the brain. This highlights the importance of exploring TFF2-related pathways in the context of obesity management towards potential therapies.

Abstract

Physiological homeostasis requires a balance between the immunological functions and the resulting damage/side effects of the immunological reactions including those related to high-fat (HF) diet. Within this context, whereas HF diet, through diverse mechanisms (such as inflammation), leads to immune-mediated damage, trefoil factor family member 2 (Tff2) represents a HF diet-induced gene. On the other hand, TFF2 both promotes tissue repair and reduces inflammation. These properties are towards counteracting the immune-mediated damage resulting from the HF diet. These observations suggest that the HF diet-induction of Tff2 could be a regulatory pathway aiming to counteract the immune-mediated damage resulting from the HF diet. Interestingly, since Tff2 expression increases with HF diet and with Tff2 also expressed in the brain, we also hypothesize that TFF2 could be a HF diet-induced food intake-control signal that reduces appetite. This hypothesis fits with counteracting the immune damage since reducing the food intake will reduce the HF intake and therefore, reduces the HF diet-induced tissue damage. Such food intake signaling would be an indirect mechanism by which TFF2 promotes tissue repair as well as a pathway worth exploring for potential obesity management pharmacotherapies.

Dysregulated Immune Responses by ASK1 Deficiency Alter Epithelial Progenitor Cell Fate and Accelerate Metaplasia Development during H. pylori Infection

The mechanism of H. pylori-induced atrophy and metaplasia has not been fully understood. Here, we demonstrate the novel role of Apoptosis signal-regulating kinase 1 (ASK1) and downstream MAPKs as a regulator of host immune responses and epithelial maintenance against H. pylori infection. ASK1 gene deficiency resulted in enhanced inflammation with numerous inflammatory cells including Gr-1+CD11b+ myeloid-derived suppressor cells (MDSCs) recruited into the infected stomach. Increase of IL-1β release from apoptotic macrophages and enhancement of TH1-polarized immune responses caused STAT1 and NF-κB activation in epithelial cells in ASK1 knockout mice. Dysregulated immune and epithelial activation in ASK1 knockout mice led to dramatic expansion of gastric progenitor cells and massive metaplasia development. Bone marrow transplantation experiments revealed that ASK1 in inflammatory cells is critical for inducing immune disorder and metaplastic changes in epithelium, while ASK1 in epithelial cells regulates cell proliferation in stem/progenitor zone without changes in inflammation and differentiation. These results suggest that H. pylori-induced immune cells may regulate epithelial homeostasis and cell fate as an inflammatory niche via ASK1 signaling.

Trefoil Factor Family (TFF) Peptides and Their Diverse Molecular Functions in Mucus Barrier Protection and More: Changing the Paradigm

Trefoil factor family peptides (TFF1, TFF2, TFF3) are typically co-secreted together with mucins. Tff1 represents a gastric tumor suppressor gene in mice. TFFs are also synthesized in minute amounts in the immune and central nervous systems. In mucous epithelia, they support rapid repair by enhancing cell migration ("restitution") via their weak chemotactic and anti-apoptotic effects. For a long time, as a paradigm, this was considered as their major biological function. Within recent years, the formation of disulfide-linked heterodimers was documented for TFF1 and TFF3, e.g., with gastrokine-2 and IgG Fc binding protein (FCGBP). Furthermore, lectin activities were recognized as enabling binding to a lipopolysaccharide of Helicobacter pylori (TFF1, TFF3) or to a carbohydrate moiety of the mucin MUC6 (TFF2). Only recently, gastric TFF1 was demonstrated to occur predominantly in monomeric forms with an unusual free thiol group. Thus, a new picture emerged, pointing to diverse molecular functions for TFFs. Monomeric TFF1 might protect the gastric mucosa as a scavenger for extracellular reactive oxygen/nitrogen species. Whereas, the TFF2/MUC6 complex stabilizes the inner layer of the gastric mucus. In contrast, the TFF3-FCGBP heterodimer (and also TFF1-FCGBP) are likely part of the innate immune defense of mucous epithelia, preventing the infiltration of microorganisms.

Structure, Function, and Therapeutic Potential of the Trefoil Factor Family in the Gastrointestinal Tract

Trefoil factor family peptides (TFF1, TFF2, and TFF3) are key players in protecting, maintaining, and repairing the gastrointestinal tract. Accordingly, they have the therapeutic potential to treat and prevent a variety of gastrointestinal disorders associated with mucosal damage. TFF peptides share a conserved motif, including three disulfide bonds that stabilize a well-defined three-loop-structure reminiscent of a trefoil. Although multiple functions have been described for TFF peptides, their mechanisms at the molecular level remain poorly understood. This review presents the status quo of TFF research relating to gastrointestinal disorders. Putative TFF receptors and protein partners are described and critically evaluated. The therapeutic potential of these peptides in gastrointestinal disorders where altered mucosal biology plays a crucial role in the underlying etiology is discussed. Finally, areas of investigation that require further research are addressed. Thus, this review provides a comprehensive update on TFF literature as well as guidance toward future research to better understand this peptide family and its therapeutic potential for the treatment of gastrointestinal disorders.

Different Forms of TFF2, A Lectin of the Human Gastric Mucus Barrier: In Vitro Binding Studies

Trefoil factor family 2 (TFF2) and the mucin MUC6 are co-secreted from human gastric and duodenal glands. TFF2 binds MUC6 as a lectin and is a constituent of the gastric mucus. Herein, we investigated human gastric extracts by FPLC and identified mainly high- but also low-molecular-mass forms of TFF2. From the high-molecular-mass forms, TFF2 can be completely released by boiling in SDS or by harsh denaturing extraction. The low-molecular-mass form representing monomeric TFF2 can be washed out in part from gastric mucosa specimens with buffer. Overlay assays with radioactively labeled TFF2 revealed binding to the mucin MUC6 and not MUC5AC. This binding is modulated by Ca²⁺ and can be blocked by the lectin GSA-II and the monoclonal antibody HIK1083. TFF2 binding was also inhibited by Me-β-Gal, but not the α anomer. Thus, both the α1,4GlcNAc as well as the juxtaperipheral β-galactoside residues of the characteristic GlcNAcα1→4Galβ1→R moiety of human MUC6 are essential for TFF2 binding. Furthermore, there are major differences in the TFF2 binding characteristics when human is compared with the porcine system. Taken together, TFF2 appears to fulfill an important role in stabilizing the inner insoluble gastric mucus barrier layer, particularly by its binding to the mucin MUC6.

Proteomics in gastroparesis: unique and overlapping protein signatures in diabetic and idiopathic gastroparesis

Macrophage-based immune dysregulation plays a critical role in development of delayed gastric emptying in diabetic mice. Loss of anti-inflammatory macrophages and increased expression of genes associated with pro-inflammatory macrophages has been reported in full-thickness gastric biopsies from gastroparesis patients. We aimed to determine broader protein expression (proteomics) and protein-based signaling pathways in gastric biopsies of diabetic (DG) and idiopathic gastroparesis (IG) patients. Additionally, we determined correlations between protein expressions, gastric emptying, and symptoms. Full-thickness gastric antrum biopsies were obtained from nine DG patients, seven IG patients, and five nondiabetic controls. Aptamer-based SomaLogic tissue scan that quantitatively identifies 1,305 human proteins was used. Protein fold changes were computed, and differential expressions were calculated using Limma. Ingenuity pathway analysis and correlations were carried out. Multiple-testing corrected P < 0.05 was considered statistically significant. Seventy-three proteins were differentially expressed in DG, 132 proteins were differentially expressed in IG, and 40 proteins were common to DG and IG. In both DG and IG, "Role of Macrophages, Fibroblasts and Endothelial Cells" was the most statistically significant altered pathway [DG false discovery rate (FDR) = 7.9 × 10^-9; IG FDR = 6.3 × 10^-12]. In DG, properdin expression correlated with GCSI bloating (r = -0.99, FDR = 0.02) and expressions of prostaglandin G/H synthase 2, protein kinase C-ζ type, and complement C2 correlated with 4 h gastric retention (r = -0.97, FDR = 0.03 for all). No correlations were found between proteins and symptoms or gastric emptying in IG. Protein expression changes suggest a central role of macrophage-driven immune dysregulation in gastroparesis, specifically, complement activation in diabetic gastroparesis.NEW & NOTEWORTHY This study uses SOMAscan, a novel proteomics assay for determination of altered proteins and associated molecular pathways in human gastroparesis. Seventy-three proteins were changed in diabetic gastroparesis, 132 in idiopathic gastroparesis compared with controls. Forty proteins were common in both. Macrophage-based immune dysregulation pathway was most significantly affected in both diabetic and idiopathic gastroparesis. Proteins involved in the complement and prostaglandin synthesis pathway were associated with symptoms and gastric emptying delay in diabetic gastroparesis.

Helicobacter pylori-induced DNA Methylation as an Epigenetic Modulator of Gastric Cancer: Recent Outcomes and Future Direction

Gastric cancer is ranked fifth in cancer list and has the third highest mortality rate. Helicobacter pylori is a class I carcinogen and a predominant etiological factor of gastric cancer. H. pylori infection may induce carcinogenesis via epigenetic alterations in the promoter region of various genes. H. pylori is known to induce hypermethylation-silencing of several tumor suppressor genes in H. pylori-infected cancerous and H. pylori-infected non-cancerous gastric mucosae. This article presents a review of the published literature mainly from the last year 15 years. The topic focuses on H. pylori-induced DNA methylation linked to gastric cancer development. The authors have used MeSH terms "Helicobacter pylori" with "epigenetic," "DNA methylation," in combination with "gastric inflammation", gastritis" and "gastric cancer" to search SCOPUS, PubMed, Ovid, and Web of Science databases. The success of epigenetic drugs such as de-methylating agents in the treatment of certain cancers has led towards new prospects that similar approaches could also be applied against gastric cancer. However, it is very important to understand the role of all the genes that have already been linked to H. pylori-induced DNA methylation in order to in order to evaluate the potential benefits of epigenetic drugs.

Exocrine tissue-driven TFF2 prevents apoptotic cell death of endocrine lineage during pancreas organogenesis

During embryogenesis, exocrine and endocrine pancreatic tissues are formed in distinct regions within the branched ductal structure in mice. We previously reported that exocrine-specific inactivation of Pdx1 by Elastase-Cre caused not only hypoplastic exocrine formation but also substantial endocrine defects resulting in diabetic phenotype, indicating the existence of an exocrine-driven factor(s) that regulates proper endocrine development. In this study, we identified Trefoil Factor 2 (TFF2) as an exocrine gene expressed from embryonic day 16.5 to adulthood in normal mice but significantly less in our Pdx1 mutants. Using in vitro explant culture of embryonic pancreatic tissue, we demonstrated that TFF2 prevented the apoptosis of insulin-producing cells but that antagonizing CXCR4, a known TFF2 receptor, suppressed this anti-apoptotic effect in the mutants. Furthermore, the antagonist in normal pancreatic tissue accelerated the apoptosis of insulin-producing cells, indicating that the TFF2/CXCR4 axis maintains embryonic insulin-producing cells in normal development. TFF2 also suppressed the apoptosis of Nkx6.1+ endocrine precursors in mutant pancreata, but this effect was unperturbed by the CXCR4 antagonist, suggesting the existence of an unknown receptor for TFF2. These findings suggest TFF2 is a novel exocrine factor that supports the survival of endocrine cells in the multiple stages of organogenesis through distinct receptors.

Antiinflammatory peptides: current knowledge and promising prospects

BACKGROUND

Inflammation is part of the regular host reaction to injury or infection caused by toxic factors, pathogens, damaged cells, irritants, and allergens. Antiinflammatory peptides (AIPs) are present in all living organisms, and many peptides from herbal, mammalian, bacterial, and marine origins have been shown to have antimicrobial and/or antiinflammatory properties.

METHODS

In this study, we investigated the effects of antiinflammatory peptides on inflammation, and highlighted the underlying mechanisms responsible for these effects.

RESULTS

In multicellular organisms, including humans, AIPs constitute an essential part of their immune system. In addition, numerous natural and synthetic AIPs are effective immunomodulators and can interfere with signal transduction pathways involved in inflammatory cytokine expression. Among them, some peptides such as antiflammin, N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), and those derived from velvet antler proteins, bee venom, horse fly salivary gland, and bovine β-casein have received considerable attention over the past few years.

CONCLUSION

This article presents an overview on the major properties and mechanisms of action associated with AIPs as immunomodulatory, chemotactic, antioxidant, and antimicrobial agents. In addition, the results of various studies dealing with effects of AIPs on numerous classical models of inflammation are reviewed and discussed.

Pancreatic-cancer-cell-derived trefoil factor 2 impairs maturation and migration of human monocyte-derived dendritic cells in vitro

Pancreatic cancer is a challenging disease with a high mortality rate. While the importance of crosstalk between cancer and immune cells has been well documented, the understanding of this complex molecular network is incomplete. Thus, identification of the secreted proteins contributing to the immunosuppressive microenvironment in pancreatic cancer is crucial for effective diagnosis and/or therapy. We utilized a public microarray dataset (GSE16515) from the Gene Expression Omnibus database to identify genes for secreted proteins in pancreatic cancer. RT-PCR and ELISA of the pancreatic cancer cell lines validated the cellular origin of the selected genes. For functional assay of the selected proteins, we utilized human-monocyte-derived dendritic cells (DCs). From the list of the secreted proteins, trefoil factor 2 (TFF2) was further examined as a potential chemokine/cytokine. While TFF2 did not significantly affect the phenotypic maturation and the allostimulatory capacity of DCs, TFF2 preferentially attracted immature (but not mature) DCs and inhibited their endocytic activity. Our data suggest that TFF2 from pancreatic cancer cells may attract immature DCs and affect the initial stage of DC maturation, thereby contributing to the induction of immune tolerance against pancreatic cancer.

The Double Face of Mucin-Type O-Glycans in Lectin-Mediated Infection and Immunity

Epithelial human blood group antigens (HBGAs) on O-glycans play roles in pathogen binding and the initiation of infection, while similar structures on secretory mucins exert protective functions. These double-faced features of O-glycans in infection and innate immunity are reviewed based on two instructive examples of bacterial and viral pathogens. Helicobacter pylori represents a class 1 carcinogen in the human stomach. By expressing blood group antigen-binding adhesin (BabA) and LabA adhesins that bind to Lewis-b and LacdiNAc, respectively, H. pylori colocalizes with the mucin MUC5AC in gastric surface epithelia, but not with MUC6, which is cosecreted with trefoil factor family 2 (TFF2) by deep gastric glands. Both components of the glandular secretome are concertedly up-regulated upon infection. While MUC6 expresses GlcNAc-capped glycans as natural antibiotics for H. pylori growth control, TFF2 may function as a probiotic lectin. In viral infection human noroviruses of the GII genogroup interact with HBGAs via their major capsid protein, VP1. HBGAs on human milk oligosaccharides (HMOs) may exert protective functions by binding to the P2 domain pocket on the capsid. We discuss structural details of the P2 carbohydrate-binding pocket in interaction with blood group H/Lewis-b HMOs and fucoidan-derived oligofucoses as effective interactors for the most prevalent norovirus strains, GII.4 and GII.17.

High salt diet can down-regulate TFF2 expression level in gastric mucosa of MGs after H. pylori infection

This study aimed to elucidate the effect of Helicobacter pylori (H. pylori) and high salt diet on Trefoil factor 2 (TFF2) expression level of Mongolian gerbils (MGs) gastric mucosa. The results of H. pylori identification and histopathology showed that H. pylori infected MGs model was built successfully. According to the immunohistochemical staining results, 25% (4/16) of H. pylori infected MGs with high salt diet showed high TFF2 expression, which was significantly lower than H. pylori infection group 61% (11/18)(P = 0.045). The results suggested that High salt diet could down-regulated TFF2 expression level of MGs gastric mucosa induced by H. pylori infection.

Trefoil Factor 2 Promotes Type 2 Immunity and Lung Repair through Intrinsic Roles in Hematopoietic and Nonhematopoietic Cells

Trefoil factors (TFFs) are small secreted proteins that regulate tissue integrity and repair at mucosal surfaces, particularly in the gastrointestinal tract. However, their relative contribution(s) to controlling baseline lung function or the extent of infection-induced lung injury are unknown issues. With the use of irradiation bone marrow chimeras, we found that TFF2 produced from both hematopoietic- and nonhematopoietic-derived cells is essential for host protection, proliferation of alveolar type 2 cells, and restoration of pulmonary gas exchange after infection with the hookworm parasite Nippostrongylus brasiliensis. In the absence of TFF2, lung epithelia were unable to proliferate and expressed reduced lung mRNA transcript levels for type 2 response-inducing IL-25 and IL-33 after infectious injury. Strikingly, even in the absence of infection or irradiation, TFF2 deficiency compromised lung structure and function, as characterized by distended alveoli and reduced blood oxygen levels relative to wild-type control mice. Taken together, we show a previously unappreciated role for TFF2, produced by either hematopoietic or nonhematopoietic sources, as a pro-proliferative factor for lung epithelial cells under steady-state and infectious injury conditions.

Transcriptional Responses in the Murine Spleen after Toxoplasma gondii Infection: Inflammasome and Mucus-Associated Genes

The spleen plays an important role in coordinating both adaptive and innate immune responses. Here, the transcriptional response to T. gondii infection in the murine spleen was characterized concerning inflammasome sensors (two different models: seven days after oral or four weeks after intraperitoneal infection). Additionally, Tff1^KO and Tff3^KO mice were investigated because TFF genes are often upregulated during inflammation. The expression of the pattern-recognition receptors Nlrp3, Nlrp12, and Nlrp1a was significantly increased after infection. This increase was diminished in Tff1^KO and Tff3^KO mice pointing towards a positive regulation of the inflammatory response by Tff1 and Tff3. Furthermore, the transcription of Tff1 (encoding a motogenic lectin) and other secretory genes was analyzed, i.e., gastrokines (Gkn), IgG Fc binding protein (Fcgbp), and the mucin Muc2. The corresponding gene products belong to an interactome protecting mucous epithelia. Tff1 was significantly induced after infection, which might increase the motility of immune cells. In contrast, Gkn3, Fcgbp, and Muc2 were downregulated seven days after oral infection; whereas four weeks after i.p. infection only Gkn3 remained downregulated. This might be an indication that Gkn3, Fcgbp, and Muc2 are involved in the transient disruption of the splenic architecture and its reorganization, which is characteristic after T. gondii infection.

Zeolite-Containing Mixture Supplementation Ameliorated Dextran Sodium Sulfate-Induced Colitis in Mice by Suppressing the Inflammatory Bowel Disease Pathway and Improving Apoptosis in Colon Mucosa

Inflammatory bowel disease (IBD) is induced by multiple environmental factors, and there is still no known treatment capable of curing the disease completely. We propose a zeolite-containing mixture (Hydryeast^®, HY)-a multi-component nutraceutical of which the main ingredients are Azumaceramics (mixture of zeolite and oyster shell burned under high temperature), citric acid, red rice yeast (monascus) and calcium stearate-as a nutraceutical intervention in IBD to ameliorate dextran sodium sulfate (DSS)-induced colitis. We show the mechanism through integrated omics using transcriptomics and proteomics. C57BL6 mice were given an AIN-93G basal diet or a 0.8% HY containing diet and sterilized tap water for 11 days. Colitis was then induced by 1.5% (w/v) DSS-containing water for 9 days. HY fed mice showed significantly improved disease activity index and colon length compared to DSS mice. Colonic mucosa microarray analysis plus RT-PCR results indicate HY supplementation may ameliorate inflammation by inhibiting the intestinal inflammatory pathway and suppress apoptosis by curbing the expression of genes like tumor protein 53 and epidermal growth factor receptor and by upregulating epithelial protection-related proteins such as epithelial cell adhesion molecule and tenascin C, thus maintaining mucosal immune homeostasis and epithelial integrity, mirroring the proteome analysis results. HY appears to have a suppressive effect on colitis.

Trefoil Factor Peptides and Gastrointestinal Function

Trefoil factor (TFF) peptides, with a 40-amino acid motif and including six conserved cysteine residues that form intramolecular disulfide bonds, are a family of mucin-associated secretory molecules mediating many physiological roles that maintain and restore gastrointestinal (GI) mucosal homeostasis. TFF peptides play important roles in response to GI mucosal injury and inflammation. In response to acute GI mucosal injury, TFF peptides accelerate cell migration to seal the damaged area from luminal contents, whereas chronic inflammation leads to increased TFF expression to prevent further progression of disease. Although much evidence supports the physiological significance of TFF peptides in mucosal defenses, the molecular and cellular mechanisms of TFF peptides in the GI epithelium remain largely unknown. In this review, we summarize the functional roles of TFF1, 2, and 3 and illustrate their action mechanisms, focusing on defense mechanisms in the GI tract.

Loss of Trefoil Factor 2 From Pancreatic Duct Glands Promotes Formation of Intraductal Papillary Mucinous Neoplasms in Mice

BACKGROUND & AIMS

Little is known about the origin of pancreatic intraductal papillary mucinous neoplasms (IPMN). Pancreatic duct glands (PDGs) are gland-like outpouches budding off the main pancreatic ducts that function as a progenitor niche for the ductal epithelium; they express gastric mucins and have characteristics of side-branch IPMNs. We investigated whether PDGs are a precursor compartment for IPMNs and the role of Trefoil factor family 2 (TFF2)-a protein expressed by PDGs and the gastric mucosa that are involved in epithelial repair and tumor suppression.

METHODS

We obtained pancreatectomy specimens from 20 patients with chronic pancreatitis, 13 with low-grade side-branch IPMNs, and 15 patients with PDAC; histologically normal pancreata were used as controls (n = 18). Samples were analyzed by immunohistochemistry to detect TFF1 and TFF2 and cell proliferation. We performed mitochondrial DNA mutational mapping studies to determine the cell lineage and fate of PDG cells. Pdx1-Cre;LSL-KRAS^G12D (KC) mice were bred with TFF2-knockout mice to generate KC/Tff2^-/- and KC/Tff2^+/- mice. Pancreata were collected and histologically analyzed for formation of IPMN, pancreatic intraepithelial neoplasias, and PDAC, in addition to proliferation and protein expression. Human pancreatic ductal epithelial cells and PDAC cell lines were transfected with vectors to overexpress or knock down TFF2 or SMAD4.

RESULTS

Histologic analysis of human samples revealed gastric-type IPMN to comprise 2 molecularly distinct layers: a basal crypt segment that expressed TFF2 and overlying papillary projections. Proliferation occurred predominantly in the PDG-containing basal segments. Mitochondrial mutation mapping revealed a 97% match between the profiles of proliferating PDG cells and their overlying nonproliferative IPMN cells. In contrast to KC mice, 2-month-old KC/Tff2^+/- and KC/Tff2^-/- mice developed prominent papillary structures in the duct epithelium with cystic metaplasia of the PDG, which resembled human IPMN; these expressed gastric mucins (MUC5AC and MUC6), but not the intestinal mucin MUC2. KC/TFF2-knockout mice developed a greater number and higher grade of pancreatic intraepithelial neoplasias than KC mice, and 1 mouse developed an invasive adenocarcinoma. Expression of TFF2 reduced proliferation of PDAC cells 3-fold; this effect required up-regulation and activation of SMAD4. We found expression of TFF2 to be down-regulated in human PDAC by hypermethylation of its promoter.

CONCLUSIONS

In histologic analyses of human IPMNs, we found PDGs to form the basal segment and possibly serve as a progenitor compartment. TFF2 has tumor-suppressor activity in the mouse pancreas and prevents formation of mucinous neoplasms.

How host regulation of Helicobacter pylori-induced gastritis protects against peptic ulcer disease and gastric cancer

The bacterial pathogen Helicobacter pylori is the etiological agent of a range of gastrointestinal pathologies including peptic ulcer disease and the major killer, gastric adenocarcinoma. Infection with this bacterium induces a chronic inflammatory response in the gastric mucosa (gastritis). It is this gastritis that, over decades, eventually drives the development of H. pylori-associated disease in some individuals. The majority of studies investigating H. pylori pathogenesis have focused on factors that promote disease development in infected individuals. However, an estimated 85% of those infected with H. pylori remain completely asymptomatic, despite the presence of pathogenic bacteria that drive a chronic gastritis that lasts many decades. This indicates the presence of highly effective regulatory processes in the host that, in most cases, keeps a check on inflammation and protect against disease. In this minireview we discuss such known host factors and how they prevent the development of H. pylori-associated pathologies.

Neural innervation stimulates splenic TFF2 to arrest myeloid cell expansion and cancer

CD11b⁺Gr-1⁺ myeloid-derived suppressor cells (MDSCs) expand in the spleen during cancer and promote progression through suppression of cytotoxic T cells. An anti-inflammatory reflex arc involving the vagus nerve and memory T cells is necessary for resolution of acute inflammation. Failure of this neural circuit could promote procarcinogenic inflammation and altered tumour immunity. Here we show that splenic TFF2, a secreted anti-inflammatory peptide, is released by vagally modulated memory T cells to suppress the expansion of MDSCs through CXCR4. Splenic denervation interrupts the anti-inflammatory neural arc, resulting in the expansion of MDSCs and colorectal cancer. Deletion of Tff2 recapitulates splenic denervation to promote carcinogenesis. Colorectal carcinogenesis could be suppressed through transgenic overexpression of TFF2, adenoviral transfer of TFF2 or transplantation of TFF2-expressing bone marrow. TFF2 is important to the anti-inflammatory reflex arc and plays an essential role in arresting MDSC proliferation. TFF2 offers a potential approach to prevent and to treat cancer.

During colorectal inflammation and cancer, myeloid cells accumulate in the spleen and suppress the host immunity response. In this study, the authors use a mouse model of colitis to demonstrate that upon vagus stimulation splenic memory T cells release TFF2, which suppresses the expansion of myeloid cells and cancer progression.

Helicobacter pylori-induced inflammation and epigenetic changes during gastric carcinogenesis

The sequence of events associated with the development of gastric cancer has been described as “the gastric precancerous cascade”. This cascade is a dynamic process that includes lesions, such as atrophic gastritis, intestinal metaplasia and dysplasia. According to this model, Helicobacter pylori (H. pylori) infection targets the normal gastric mucosa causing non-atrophic gastritis, an initiating lesion that can be cured by clearing H. pylori with antibiotics or that may then linger in the case of chronic infection and progress to atrophic gastritis. The presence of virulence factors in the infecting H. pylori drives the carcinogenesis process. Independent epidemiological and animal studies have confirmed the sequential progression of these precancerous lesions. Particularly long-term follow-up studies estimated a risk of 0.1% for atrophic gastritis/intestinal metaplasia and 6% in case of dysplasia for the long-term development of gastric cancer. With this in mind, a better understanding of the genetic and epigenetic changes associated with progression of the cascade is critical in determining the risk of gastric cancer associated with H. pylori infection. In this review, we will summarize some of the most relevant mechanisms and focus predominantly but not exclusively on the discussion of gene promoter methylation and miRNAs in this context.

TFF Peptides Play a Role in the Immune Response Following Oral Infection of Mice with Toxoplasma Gondii

The peptide trefoil factor family 3 (TFF3) is a major constituent of the intestinal mucus, playing an important role in the repair of epithelial surfaces. To further understand the role of TFF3 in the protection of intestinal epithelium, we tested the influence of TFF3 in a murine Toxoplasma gondii-induced ileitis model. Surprisingly, TFF3^KO mice showed a reduced immune response in the ileum when compared to wild-type animals. Interleukin-12 and interferon-γ expression levels as well as the number of CD4⁺ lymphocytes were reduced in the infected TFF3^KO mice. These effects were in line with the trend of elevated parasite levels in the ileum. Moreover, TFF1 expression was upregulated in the spleen of infected mice. These initial results indicate that TFF3 is involved in the immune pathology of T. gondii infection-induced intestinal inflammation. Thus far, the mechanisms of how TFF3 influences the immune response are not fully understood. Further studies should identify if TFF3 affects mucus sensing of dendritic cells and how TFF3 is involved in regulating the immune response as an intrinsic secretory peptide of immune cells.

TFF2, a MUC6-binding lectin stabilizing the gastric mucus barrier and more (Review)

The peptide TFF2 (formerly 'spasmolytic polypeptide'), a member of the trefoil factor family (TFF) containing two TFF domains, is mainly expressed together with the mucin MUC6 in the gastric epithelium and duodenal Brunner's glands. Pathologically, TFF2 expression is observed ectopically during stone diseases, chronic inflammatory conditions and in several metaplastic and neoplastic epithelia; most prominent being the 'spasmolytic polypeptide-expressing metaplasia' (SPEM), which is an established gastric precancerous lesion. TFF2 plays a critical role in maintaining gastric mucosal integrity and appears to restrain tumorigenesis in the stomach. Recently, porcine TFF2 has been shown to interact with the gastric mucin MUC6 and thus stabilize the gastric mucus barrier. On the one hand, TFF2 binds to MUC6 via non-covalent lectin interactions with the glycotope GlcNAcα1→4Galβ1→R. On the other hand, TFF2 is probably also covalently bound to MUC6 via disulfide bridges. Thus, implications for the complex multimeric assembly, cross-linking, and packaging of MUC6 as well as the rheology of gastric mucus are discussed in detail in this review. Furthermore, TFF2 is also expressed in minor amounts in the immune and nervous systems. Thus, similar to galectins, its lectin activity would perfectly enable TFF2 to form multivalent complexes and cross-linked lattices with a plethora of transmembrane glycoproteins and thus modulate different signal transduction processes. This could explain the multiple and diverse biological effects of TFF2 [e.g., motogenic, (anti)apoptotic, and angiogenic effects]. Finally, a function during fertilization is also possible for TFF domains because they occur as shuffled modules in certain zona pellucida proteins.

Mucin gene mRNA levels in broilers challenged with eimeria and/or Clostridium perfringens

The effects of Eimeria (EM) and Clostridium perfringens (CP) challenges on the mRNA levels of genes involved in mucin (Muc) synthesis (Muc2, Muc5ac, Muc13, and trefoil family factor-2 [TFF2]), inflammation (tumor necrosis factor alpha [TNF-alpha] and interleukin-18 [IL-18]), and metabolic processes (cluster of differentiation [CD]36) in the jejunum of broilers were investigated. Two parallel experiments involving 1) EM challenge and 2) EM and CP challenges were conducted. The first experiment was a 2 X 2 study with 12 birds per treatment (N = 48) involving fishmeal substitution (25%) in the diet (FM) and EM challenge. The treatments were: Control (FM-, EM-), Fishmeal (FM+, EM-), EM challenge (FM-, EM+), and fishmeal substitution and EM challenge (FM+, EM+). The second experiment was a 2 X 2 X 2 experiment with six birds per treatment (N = 48) involving fishmeal (FM-, FM+), Eimeria (EM-, EM+), and C perfringens (CP-, CP+). In both arms of the study, male broilers were given a starter diet for the whole period of 16 days, except those assigned to FM+, where 25% of the starter ration was replaced with fishmeal from days 8 to 14. EM inoculation was performed on day 9 and CP inoculation on days 14 and 15. The EM challenge birds were euthanatized for sampling on day 13; postmortem examination and sampling for the Eimeria plus C perfringens challenge arm of the study were on day 16. In the Eimeria challenge arm of the study, fishmeal supplementation significantly suppressed the mRNA levels of TNF-alpha, TFF2, and IL-18 pre-CP inoculation but simultaneously increased the levels of Muc13 and CD36 mRNAs. Birds challenged with Eimeria exhibited increased mRNA levels of Muc13, Muc5ac, TNF-alpha, and IL-18. In the Eimeria and C. perfringens challenge arm, birds exposed to EM challenge exhibited significantly lower mRNA levels of Muc2 and CD36. The mRNA levels of CD36 were also significantly suppressed by CP challenge. Our results showed that the transcription of mucin synthesis genes in the jejunum of broilers is modulated by fishmeal inclusion in the diet. Furthermore, we show for the first time suppression of CD36 mRNA levels in the intestine of broilers challenged with Eimeria or C. perfringens.

IL33 Is a Stomach Alarmin That Initiates a Skewed Th2 Response to Injury and Infection

BACKGROUND & AIMS

Interleukin (IL)33 is a recently described alarmin that is highly expressed in the gastric mucosa and potently activates Th2 immunity. It may play a pivotal role during Helicobacter pylori infection. Here, we delineate the role of IL33 in the normal gastric mucosa and in response to gastropathy.

METHODS

IL33 expression was evaluated in mice and human biopsy specimens infected with H pylori and in mice after dosing with aspirin. IL33 expression was localized in the gastric mucosa using immunofluorescence. Mice were given 1 or 7 daily doses of recombinant IL33 (1 μg/dose), and the stomach and the spleen responses were quantified morphologically, by flow cytometry and using quantitative reverse-transcription polymerase chain reaction and immunoblotting.

RESULTS

In mice, the IL33 protein was localized to the nucleus of a subpopulation of surface mucus cells, and co-localized with the surface mucus cell markers Ulex Europaeus 1 (UEA1), and Mucin 5AC (Muc5AC). A small proportion of IL33-positive epithelial cells also were Ki-67 positive. IL33 and its receptor Interleukin 1 receptor-like 1 (ST2) were increased 4-fold after acute (1-day) H pylori infection, however, this increase was not apparent after 7 days and IL33 expression was reduced 2-fold after 2 months. Similarly, human biopsy specimens positive for H pylori had a reduced IL33 expression. Chronic IL33 treatment in mice caused systemic activation of innate lymphoid cell 2 and polarization of macrophages to the M2 phenotype. In the stomach, IL33-treated mice developed transmural inflammation and mucous metaplasia that was mediated by Th2/signal transducer and activator of transcription 3 signaling. Rag-1^-/- mice, lacking mature lymphocytes, were protected from IL33-induced gastric pathology.

CONCLUSIONS

IL33 is highly expressed in the gastric mucosa and promotes the activation of T helper 2-cytokine-expressing cells. The loss of IL33 expression after prolonged H pylori infection may be permissive for the T helper 1-biased immune response observed during H pylori infection and subsequent precancerous progression.

TFF2 deficiency exacerbates weight loss and alters immune cell and cytokine profiles in DSS colitis, and this cannot be rescued by wild-type bone marrow

The trefoil factor TFF2 is a member of a tripartite family of small proteins that is produced by the stomach and the colon. Recombinant TFF2, when applied intrarectally in a rodent model of hapten colitis, hastens mucosal healing and reduces inflammatory indexes. Additionally, TFF2 is expressed in immune organs, supporting a potential immunomodulatory and reparative role in the bowel. In this study we confirm that TFF2 is expressed in the colon and is specifically enriched in epithelial cells relative to colonic leukocytes. TFF2-deficient, but not TFF1-deficient, mice exhibit a more severe response to acute or chronic dextran sulfate (DSS)-induced colitis that correlates with a 50% loss of expression of TFF3, the principal colonic trefoil. In addition, the response to acute colitis is associated with altered expression of IL-6 and IL-33, but not other inflammatory cytokines. While TFF2 can reduce macrophage responsiveness and block inflammatory cell recruitment to the colon, the major role in limiting the susceptibility to acute colitis appears to be maintenance of barrier function. Bone marrow transfer experiments demonstrate that leukocyte expression of TFF2 is not sufficient for prevention of colitis induction but, rather, that the gastrointestinal epithelium is the primary source of TFF2. Together, these findings illustrate that epithelial TFF2 is an important endogenous regulator of gut mucosal homeostasis that can modulate immune and epithelial compartments. Because of its extreme stability, even in the corrosive gut lumen, TFF2 is an attractive candidate as an oral therapeutic scaffold for future drug development in the treatment of inflammatory bowel disease.

Human trefoil factor 2 is a lectin that binds α-GlcNAc-capped mucin glycans with antibiotic activity against Helicobacter pylori

Helicobacter pylori infection is the major cause of gastric cancer and remains an important health care challenge. The trefoil factor peptides are a family of small highly conserved proteins that are claimed to play essential roles in cytoprotection and epithelial repair within the gastrointestinal tract. H. pylori colocalizes with MUC5AC at the gastric surface epithelium, but not with MUC6 secreted in concert with TFF2 by deep gastric glands. Both components of the gastric gland secretome associate non-covalently and show increased expression upon H. pylori infection. Although blood group active O-glycans of the Lewis-type form the basis of H. pylori adhesion to the surface mucin layer and to epithelial cells, α1,4-GlcNAc-capped O-glycans on gastric mucins were proposed to inhibit H. pylori growth as a natural antibiotic. We show here that the gastric glycoform of TFF2 is a calcium-independent lectin, which binds with high specificity to O-linked α1,4-GlcNAc-capped hexasaccharides on human and porcine stomach mucin. The structural assignments of two hexasaccharide isomers and the binding active glycotope were based on mass spectrometry, linkage analysis, (1)H nuclear magnetic resonance spectroscopy, glycan inhibition, and lectin competition of TFF2-mucin binding. Neoglycolipids derived from the C3/C6-linked branches of the two isomers revealed highly specific TFF2 binding to the 6-linked trisaccharide in GlcNAcα1-4Galβ1-4GlcNAcβ1-6(Fucα1-2Galβ1-3)GalNAc-ol(Structure 1). Supposedly, lectin TFF2 is involved in protection of gastric epithelia via a functional relationship to defense against H. pylori launched by antibiotic α1,4-GlcNAc-capped mucin glycans. Lectin-carbohydrate interaction may have also an impact on more general functional aspects of TFF members by mediating their binding to cell signaling receptors.

3-Hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor (statin)-induced 28-kDa interleukin-1β interferes with mature IL-1β signaling

Multiple clinical trials have shown that the 3-hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors known as statins have anti-inflammatory effects. However, the underlying molecular mechanism remains unclear. The proinflammatory cytokine interleukin-1β (IL-1β) is synthesized as a non-active precursor. The 31-kDa pro-IL-1β is processed into the 17-kDa active form by caspase-1-activating inflammasomes. Here, we report a novel signaling pathway induced by statins, which leads to processing of pro-IL-1β into an intermediate 28-kDa form. This statin-induced IL-1β processing is independent of caspase-1- activating inflammasomes. The 28-kDa form of IL-1β cannot activate interleukin-1 receptor-1 (IL1R1) to signal inflammatory responses. Instead, it interferes with mature IL-1β signaling through IL-1R1 and therefore may dampen inflammatory responses initiated by mature IL-1β. These results may provide new clues to explain the anti-inflammatory effects of statins.

Mechanistic insights into the contribution of epithelial damage to airway remodeling. Novel therapeutic targets for asthma

It has been suggested that an inherent airway epithelial repair defect is the root cause of airway remodeling in asthma. However, the relationship between airway epithelial injury and repair, airway remodeling, and airway hyperresponsiveness (AHR) has not been directly examined. We investigated the contribution of epithelial damage and repair to the development of airway remodeling and AHR using a validated naphthalene (NA)-induced murine model of airway injury. In addition, we examined the endogenous versus exogenous role of the epithelial repair peptide trefoil factor 2 (TFF2) in disease pathogenesis. A single dose of NA (200 mg/kg in 10 ml/kg body weight corn oil [CO] vehicle, intraperitoneally) was administered to mice. Control mice were treated with CO (10 ml/kg body weight, intraperitoneally). At 12, 24, 48, and 72 hours after NA or CO injection, AHR and various measures of airway remodeling were examined by invasive plethysmography and morphometric analyses, respectively. TFF2-deficient mice and intranasal treatment were used to examine the role of the epithelial repair peptide. NA treatment induced denudation and apoptosis of airway epithelial cells, goblet cell metaplasia, elevated AHR, and increased levels of endogenous TFF2. Airway epithelial changes peaked at 12 hours after NA treatment, whereas airway remodeling changes were observed from 48 hours. TFF2 was protective against epithelial damage and induced remodeling and was found to mediate organ protection via a platelet-derived growth factor-associated mechanism. Our findings directly demonstrate the contribution of epithelial damage to airway remodeling and AHR and suggest that preventing airway epithelial damage and promoting epithelial repair may have therapeutic implications for asthma treatment.

Trefoil factor family member 2 (Tff2) KO mice are protected from high-fat diet-induced obesity

INTRODUCTION

Trefoil factor family member 2 (Tff2) is a small gut peptide, mainly known for its protective and healing functions. As previously demonstrated, high-fat (HF) feeding can rapidly and specifically modulate Tff2 transcription in key tissues of mice, including the duodenum and mesenteric adipose tissue, therefore suggesting a novel role for this gene in energy balance.

DESIGN AND METHODS

To explore whether and how Tff2 can influence feeding behavior and energy metabolism, Tff2 knock-out (KO) mice were challenged with HF diet for 12 weeks, hence food and energy intakes, body composition, as well as energy excretion and serum lipid and hormonal levels were analyzed. Finally, energy efficiency was estimated.

RESULTS

Tff2 KO mice showed a greater appetite and higher energy intake compared to wild-type (WT). Consistently, they presented lower levels of serum leptin, and increased transcription of agouti-related protein (Agrp) in the hypothalamus. Though energy and triglyceride fecal excretion were augmented in Tff2 KO mice, digestible energy intake was superior. However, KO mice were finally protected from HF diet-induced obesity, and accumulated less weight and fat depots than WT animals, while keeping a normal lean mass. Energy efficiency was lower in HF-KO mice, while energy expenditure and locomotor activity were globally increased.

CONCLUSIONS

The present work demonstrates previously unsuspected roles for Tff2 and suggests it to be a mastermind in the control of energy balance and a promising therapeutic target for obesity.

The unfolded protein response is activated in Helicobacter-induced gastric carcinogenesis in a non-cell autonomous manner

Mucous metaplasia (MM) is an aberrant secretory phenotype that arises during Helicobacter-induced gastric carcinogenesis. HSPA5, a key modulator of the unfolded protein response (UPR) activated by endoplasmic reticulum (ER) stress is overexpressed in gastric cancer (GC). We studied activation of the UPR in MM and GC in humans and mice. We assessed RNA and protein levels of ER stress markers (HSPA5, XBP1, and CHOP) in human GC, and correlated with Helicobacter pylori (H. pylori) status, then surveyed HSPA5 in normal gastric mucosa and gastric pre-neoplasia including gastritis and intestinal metaplasia (IM). The role of H. pylori infection in the UPR was assessed by co-culture with AGS GC cells. ER stress markers in metaplasia and dysplasia from transgenic K19-Wnt1/C2mE mice and C57Bl/6 mice with chronic Helicobacter felis (H. felis) infection were compared. HSPA5 was overexpressed in 24/73 (33%) of human GC. Induction of HSPA5 and XBP1 splicing was associated with H. pylori-associated GC (P=0.007 for XBP1 splicing). HSPA5 was overexpressed in MM but not gastritis in patients with H. pylori infection. Stimulation of AGS cells with CagA-positive H. pylori suppressed HSPA5 expression and XBP1 splicing. In the normal gastric mucosa of human and mouse, HSPA5 was constitutively expressed in MIST1-positive chief cells. Increased Hspa5 and Chop expression were found in dysplasia of C57Bl/6 mice with chronic H. felis infection but was absent in spontaneous gastric dysplasia in K19-Wnt1/C2mE mice with concomitant loss of Mist1 expression, similar to that observed in H. pylori-associated human GC. Induction of the UPR in the milieu of Helicobacter-induced chronic inflammation and MM may promote neoplastic transformation of Helicobacter-infected gastric mucosa.

Human gastric TFF2 peptide contains an N-linked fucosylated N,N'-diacetyllactosediamine (LacdiNAc) oligosaccharide

In the human stomach, the peptide trefoil factor family 2 (TFF2) is secreted together with the mucin MUC6 by mucous neck cells (MNCs) and antral gland cells. TFF2 is strongly associated with the gastric mucus and promotes gastric restitution. Here, TFF2 was purified from the human corpus and antrum, respectively, by size-exclusion chromatography, and the N-linked glycan structure at N-15 of the mature peptide was determined. As a hallmark, the unusual monofucosylated N,N'-diacetylhexosediamine (tentatively assigned as GalNAcβ1 → 4GlcNAc, LacdiNAc) modification was detected as the terminal structure of a bi-antennary complex type N-glycan exhibiting also core fucosylation. Replicate analyses did not show microheterogeneities in the fraction of peptide-N-glycosidase F cleaved and permethylated N-glycans when analyzed by matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS). On the glycopeptide level, a minor glycan microheterogeneity was evident in liquid chromatography-electrospray ionization (ESI)-MS, demonstrating the presence of underfucosylated species. The tryptic TFF2 N-glycopeptide p34-39 (LSPHNR N-glycosylated with Fuc3Hex3HexNAc6) was identified by both ESI-tandem mass spectrometry and MALDI-post-source decay analysis. Lectin analyses with the Wisteria floribunda agglutinin indicated the potential presence of LacdiNAc terminating glycans and revealed minor differences between TFF2 from fundic units, i.e. MNCs, and antral units, i.e. antral gland cells. Strikingly, on the level of the primary structure, there was no indication that the formation of the proposed LacdiNAc structure is cis-controlled by a peptidic determinant related to the published sequences.

Trefoil factor 2 negatively regulates type 1 immunity against Toxoplasma gondii

IL-12-mediated type 1 inflammation confers host protection against the parasitic protozoan Toxoplasma gondii. However, production of IFN-γ, another type 1 inflammatory cytokine, also drives lethality from excessive injury to the intestinal epithelium. As mechanisms that restore epithelial barrier function following infection remain poorly understood, this study investigated the role of trefoil factor 2 (TFF2), a well-established regulator of mucosal tissue repair. Paradoxically, TFF2 antagonized IL-12 release from dendritic cells (DCs) and macrophages, which protected TFF2-deficient (TFF2(-/-)) mice from T. gondii pathogenesis. Dysregulated intestinal homeostasis in naive TFF2(-/-) mice correlated with increased IL-12/23p40 levels and enhanced T cell recruitment at baseline. Infected TFF2(-/-) mice displayed low rates of parasite replication and reduced gut immunopathology, whereas wild-type (WT) mice experienced disseminated infection and lethal ileitis. p38 MAPK activation and IL-12p70 production was more robust from TFF2(-/-)CD8+ DC compared with WT CD8+ DC and treatment of WT DC with rTFF2 suppressed TLR-induced IL-12/23p40 production. Neutralization of IFN-γ and IL-12 in TFF2(-/-) animals abrogated resistance shown by enhanced parasite replication and infection-induced morbidity. Hence, TFF2 regulated intestinal barrier function and type 1 cytokine release from myeloid phagocytes, which dictated the outcome of oral T. gondii infection in mice.

Trefoil factor 2 rapidly induces interleukin 33 to promote type 2 immunity during allergic asthma and hookworm infection

The repair protein trefoil factor 2 promotes Th2 responses to helminth infection and allergens in part by inducing IL-33.

The molecular mechanisms that drive mucosal T helper type 2 (T_H2) responses against parasitic helminths and allergens remain unclear. In this study, we demonstrate in mice that TFF2 (trefoil factor 2), an epithelial cell–derived repair molecule, is needed for the control of lung injury caused by the hookworm parasite Nippostrongylus brasiliensis and for type 2 immunity after infection. TFF2 is also necessary for the rapid production of IL-33, a T_H2-promoting cytokine, by lung epithelia, alveolar macrophages, and inflammatory dendritic cells in infected mice. TFF2 also increases the severity of allergic lung disease caused by house dust mite antigens or IL-13. Moreover, TFF2 messenger RNA expression is significantly increased in nasal mucosal brushings during asthma exacerbations in children. These experiments extend the biological functions of TFF2 from tissue repair to the initiation and maintenance of mucosal T_H2 responses.

Innate immune responses to Helicobacter pylori infection: an overview

Innate immune receptors detect Helicobacter pylori infection and trigger downstream signaling events that result in the production of cytokines and interferon-β. This chapter gives an overview of the receptors and their roles in responding to H. pylori infection and details the downstream signaling events. The tools that have been developed to study the innate immune response to H. pylori are also discussed. Understanding the immune response to H. pylori is critical to develop better treatments for H. pylori-induced disease states including gastric malignancies and cancer.

Gastric Helicobacter spp. in animal models: pathogenesis and modulation by extragastric coinfections

Animal models are used to study complex host, microbial, and environmental influences associated with gastric Helicobacter infection. Evidence that gastric helicobacters are pathogenic in animals first came from ferrets. Felids, nonhuman primates, and many other species also harbor stomach helicobacters. Today, mice are preferred by most researchers for scientific investigation because of cost-efficiencies, rapid reproduction, choice of laboratory reagents, and availability of genetically engineered models. Infection with Helicobacter felis or H. pylori Sydney strain-1 in appropriate mouse strains produces disease with remarkable similarities to H. pylori in humans. Due to recent advances in genetic engineering, in vivo imaging, and system-wide genomics and proteomics, these models will become even more widespread in the future. Recently, it has been shown that extragastric infections can dramatically affect the severity of disease induced by gastric Helicobacter spp. through heterologous immunity. These models provide proof-of-principle for the "African enigma" wherein gastric cancer is underrepresented in low-lying tropical countries with concurrently high H. pylori and internal parasite prevalence. Helicobacter gastritis and carcinogenesis in mouse models may be augmented or ameliorated by other infectious agents depending on the character of the invoked immune response. Knowledge gained from the Human Microbiome Project and other investigations is certain to shed new light on the influence of extragastric bacterial, viral, fungal, and parasitic coinfections on H. pylori-associated peptic ulcer disease and gastric adenocarcinoma.