Protein kinase C and ERK activation are required for TFF-peptide-stimulated bronchial epithelial cell migration and tumor necrosis factor-alpha-induced interleukin-6 (IL-6) and IL-8 secretion

A fusion protein approach to integrate antiviral and anti-inflammatory activities for developing new therapeutics against influenza A virus infection

Human interferon α2 (IFNα2) is a cytokine with broad-spectrum antiviral activity, and its engineered forms are widely used to treat viral infections. However, IFNα2 may trigger proinflammatory responses and underlying side effects during treatment. Trefoil factor 2 (TFF2) is a secreted protein with anti-inflammatory properties. Here, we explored whether coupling IFNα2 to TFF2 in a two-in-one fusion form could combine the beneficial effects of both molecules on viral infections toward a more desirable treatment outcome. We engineered two forms of human IFNα2 and TFF2 fusion proteins, IFNα2-TFF2-Fc (ITF) and TFF2-IFNα2-Fc (TIF), and examined their properties in vitro in comparison to IFNα2 and TFF2 alone. RNA-Seq was further used to explore such comparison on dynamic gene regulation at transriptomic level. These in vitro assessments collectively indicated that TIF largely retained the antiviral activity of IFNα2 while being a weaker inflammation inducer, consistent with the presence of TFF2 activity. We further demonstrated the superiority of TIF over IFNα2 or TFF2 alone in treating influenza infection using a mouse infection model. Together, our study provided evidence supporting that, by possessing antiviral activity conferred by IFNα2 with complementation from TFF2 in suppressing the inflammatory side effects, the fusion proteins, particularly TIF, represent more effective agents against influenza and other respiratory viral infections than IFNα2 or TFF2 alone. It implies that merging two molecules with complementary functions holds potential for developing novel therapeutics against viral infections.

SARS-CoV-2 spike protein receptor binding domain promotes IL-6 and IL-8 release via ATP/P2Y2 and ERK1/2 signaling pathways in human bronchial epithelia

The spike protein of SARS-CoV-2 as well as its receptor binding domain (RBD) has been demonstrated to be capable of activating the release of pro-inflammatory mediators in endothelial cells and immune cells such as monocytes. However, the effects of spike protein or its RBD on airway epithelial cells and mechanisms underlying these effects have not been adequately characterized. Here, we show that the RBD of spike protein alone can induce bronchial epithelial inflammation in a manner of ATP/P2Y2 dependence. Incubation of human bronchial epithelia with RBD induced IL-6 and IL-8 release, which could be inhibited by antibody. The incubation of RBD also up-regulated the expression of inflammatory indicators such as ho-1 and mkp-1. Furthermore, ATP secretion was observed after RBD treatment, P2Y2 receptor knock down by siRNA significantly suppressed the IL-6 and IL-8 release evoked by RBD. Additionally, S-RBD elevated the phosphorylation level of ERK1/2, and the effect that PD98059 can inhibit the pro-inflammatory cytokine release suggested the participation of ERK1/2. These novel findings provide new evidence of SARS-CoV-2 on airway inflammation and introduce purinergic signaling as promising treatment target.

Pro-inflammatory action of formoterol in human bronchial epithelia

Despite the wide usage of β2-adrenoceptor agonists in asthma treatment, they do have side effects such as aggravating inflammation. We previously reported that isoprenaline induced Cl- secretion and IL-6 release via cAMP-dependent pathways in human bronchial epithelia, but the mechanisms underlying the inflammation-aggravation effects of β2-adrenoceptor agonists remain pooly understood. In this study, we investigated formoterol, a more specific β2-adrenoceptor agonist, -mediated signaling pathways involved in the production of IL-6 and IL-8 in 16HBE14o- human bronchial epithelia. The effects of formoterol were detected in the presence of PKA, exchange protein directly activated by cAMP (EPAC), cystic fibrosis transmembrane conductance regulator (CFTR), extracellular signal-regulated protein kinase (ERK)1/2 and Src inhibitors. The involvement of β-arrestin2 was determined using siRNA knockdown. Our results indicate that formoterol can induce IL-6 and IL-8 secretion in concentration-dependent manner. The PKA-specific inhibitor, H89, partially inhibited IL-6 release, but not IL-8. Another intracellular cAMP receptor, EPAC, was not involved in either IL-6 or IL-8 release. PD98059 and U0126, two ERK1/2 inhibitors, blocked IL-8 while attenuated IL-6 secretion induced by formoterol. Furthermore, formoterol-induced IL-6 and IL-8 release was attenuated by Src inhibitors, namely dasatinib and PP1, and CFTRinh172, a CFTR inhibitor. In addition, knockdown of β-arrestin2 by siRNA only suppressed IL-8 release when a high concentration of formoterol (1 μM) was used. Taken together, our results suggest that formoterol stimulates IL-6 and IL-8 release which involves PKA/Src/ERK1/2 and/or β-arrestin2 signaling pathways.

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.

Chemokine-mucinome interplay in shaping the heterogeneous tumor microenvironment of pancreatic cancer

Pancreatic cancer (PC) is exemplified by a complex immune-suppressive, fibrotic tumor microenvironment (TME), and aberrant expression of mucins. The constant crosstalk between cancer cells, cancer-associated fibroblasts (CAFs), and the immune cells mediated by the soluble factors and inflammatory mediators including cytokines, chemokines, reactive oxygen species (ROS) promote the dynamic temporal switch towards an immune-escape phenotype in the neoplastic cells and its microenvironment that bolsters disease progression. Chemokines have been studied in PC pathogenesis, albeit poorly in the context of mucins, tumor glycocalyx, and TME heterogeneity (CAFs and immune cells). With correlative analysis from PC patients' transcriptome data, support from available literature, and scientific arguments-based speculative extrapolations in terms of disease pathogenesis, we have summarized in this review a comprehensive understanding of chemokine-mucinome interplay during stromal modulation and immune-suppression in PC. Future studies should focus on deciphering the complexities of chemokine-mediated control of glycocalyx maturation, immune infiltration, and CAF-associated immune suppression. Knowledge extracted from such studies will be beneficial to mechanistically correlate the mucin-chemokine abundance in serum versus pancreatic tumors of patients, which may aid in prognostication and stratification of PC patients for immunotherapy.

Trefoil Factor Family: A Troika for Lung Repair and Regeneration

Tissue damage in the upper and lower airways caused by mechanical abrasion, noxious chemicals, or pathogenic organisms must be followed by rapid restorative processes; otherwise, persistent immunopathology and disease may ensue. This review will discuss evidence for the important role served by trefoil factor (TFF) family members in healthy and diseased airways of humans and rodents. Collectively, these peptides serve to both maintain and restore homeostasis through their regulation of the mucous layer and their control of cell motility, cell differentiation, and immune function in the upper and lower airways. We will also discuss important differences in which trefoil member tracks with homeostasis and disease between humans and mice, which poses a challenge for research in this area. Moreover, we discuss new evidence supporting newly identified receptor binding partners in the leucine-rich repeat and immunoglobulin-like domain-containing NoGo (LINGO) family in mediating the biological effects of TFF proteins in mouse models of epithelial repair and infection. Recent advances in our knowledge regarding TFF peptides suggest that they may be reasonable therapeutic targets in the treatment of upper and lower airway diseases of diverse etiologies. Further work understanding their role in airway homeostasis, repair, and inflammation will benefit from these newly uncovered receptor-ligand interactions.

Identification and Validation of Prognostic Factors of Lipid Metabolism in Obstructive Sleep Apnea

Background: Obstructive sleep apnea (OSA) is considered to be an independent factor affecting lipid metabolism. This study explored the relationship between immune genes and lipid metabolism in OSA.

Methods: Immune-related Differentially Expressed Genes (DEGs) were identified by analyzing microarray data sets from the Gene Expression Omnibus (GEO) database. Subsequently, we conducted protein-protein interaction (PPI) network analysis and calculated their Gene Ontology (GO) semantic similarity. The GO, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, Disease Ontology (DO), gene set enrichment analysis (GSEA), and gene set variation analysis (GSVA) were employed for functional enrichment analyses and to determine the most significant functional terms. Combined with the results of boruta and random forest, we selected predictors to build a prognostic model, along with seeking out the potential TFs and target drugs for the predictive genes.

Results: Immune-related DEGs included 64 genes upregulated and 98 genes downregulated. The enrichment analysis might closely associate with cell adhesion and T cell-mediated immunity pathways and there were many DEGs involved in lipid and atherosclerosis signaling pathways. The highest-ranking hub gene in PPI network have been reported lowly expressed in OSA. In line with the enrichment analysis, DO analysis reveal that respiratory diseases may be associated with OSA besides immune system disorders. Consistent with the result of the KEGG pathway, the analysis of GSVA revealed that the pro-inflammation pathways are associated with OSA. Monocytes and CD8 T cells were the predominant immune cells in adipose tissue. We built a prognostic model with the top six genes, and the prognostic genes were involved in the polarization of macrophage and differentiation of T lymphocyte subsets. In vivo experimental verification revealed that EPGN, LGR5, NCK1 and VIP were significantly down-regulated while PGRMC2 was significantly up-regulated in mouse model of OSA.

Conclusions: Our study demonstrated strong associations between immune genes and the development of dyslipidemia in OSA. This work promoted the molecular mechanisms and potential targets for the regulation of lipid metabolism in OSA.

β2-Adrenoceptor Activation Stimulates IL-6 Production via PKA, ERK1/2, Src, and Beta-Arrestin2 Signaling Pathways in Human Bronchial Epithelia

Objective

β₂-Adrenoceptor agonists are widely used to treat asthma because of their bronchial-dilation effects. We previously reported that isoprenaline, via the apical and basolateral β₂-adrenoceptor, induced Cl⁻ secretion by activating cyclic AMP (cAMP)-dependent pathways in human bronchial epithelia. Despite these results, whether and how the β₂-adrenoceptor-mediated cAMP-dependent pathway contributes to pro-inflammatory cytokine release in human bronchial epithelia remains poorly understood.

Methods

We investigated β₂-adrenoceptor-mediated signaling pathways involved in the production of two pro-inflammatory cytokines, interleukin (IL)-6 and IL-8, in 16HBE14o- human bronchial epithelia. The effects of isoprenaline or formoterol were assessed in the presence of protein kinase A (PKA), exchange protein directly activated by cAMP (EPAC), Src, and extracellular signal-regulated protein kinase (ERK)1/2 inhibitors. The involvement of β-arrestin2 was examined using siRNA knockdown.

Results

Isoprenaline and formoterol (both β₂ agonists) induced IL-6, but not IL-8, release, which could be inhibited by ICI 118,551 (β₂ antagonist). The PKA-specific inhibitor, H89, partially inhibited IL-6 release. Another intracellular cAMP receptor, EPAC, was not involved in IL-6 release. Isoprenaline-mediated IL-6 secretion was attenuated by dasatinib, a Src inhibitor, and PD98059, an ERK1/2 inhibitor. Isoprenaline treatment also led to ERK1/2 phosphorylation. In addition, knockdown of β-arrestin2 by siRNA specifically suppressed cytokine release when a high concentration of isoprenaline (1 mM) was used.

Conclusion

Our results suggest that activation of the β₂-adrenoceptor in 16HBE14o- cells stimulated the PKA/Src/ERK1/2 and/or β-arrestin2 signaling pathways, leading to IL-6 release. Therefore, our data reveal that β₂-adrenoceptor signaling plays a role in the immune regulation of human airway epithelia.

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.

Trefoil Factor 3 (TFF3) Is Involved in Cell Migration for Skeletal Repair

The aim of the study was to explore the possible role of Trefoil Factor Family peptide 3 (TFF3) for skeletal repair. The expression of TFF3 was analyzed in human joint tissues as well as in a murine bone fracture model. Serum levels of TFF3 following a defined skeletal trauma in humans were determined by ELISA. The mRNA expression of TFF3 was analyzed under normoxia and hypoxia. Expression analysis after stimulation of human mesenchymal progenitor cells (MPCs) with TFF3 was performed by RT² Profiler PCR Array. The effect of recombinant human (rh)TFF3 on MPCs was analysed by different migration and chemotaxis assays. The effect on cell motility was also visualized by fluorescence staining of F-Actin. TFF3 was absent in human articular cartilage, but strongly expressed in the subchondral bone and periosteum of adult joints. Strong TFF3 immunoreactivity was also detected in murine fracture callus. Serum levels of TFF3 were significantly increased after skeletal trauma in humans. Expression analysis demonstrated that rhTFF3 significantly decreased mRNA of ROCK1. Wound healing assays showed increased cell migration of MPCs by rhTFF3. The F-Actin cytoskeleton was markedly influenced by rhTFF3. Cell proliferation was not increased by rhTFF3. The data demonstrate elevated expression of TFF3 after skeletal trauma. The stimulatory effects on cell motility and migration of MPCs suggest a role of TFF3 in skeletal repair.

Possible application of trefoil factor family peptides in gastroesophageal reflux and Barrett's esophagus

Gastroesophageal reflux disease (GERD) is a chronic disorder of the digestive tract characterised mainly by a heartburn. Being one of the most common gastrointestinal diseases, the prevalence of GERD reaches up to 25.9% in Europe. Barrett's esophagus (BE) is an acquired condition characterized by the replacement of the normal stratified squamous epithelium with metaplastic columnar epithelium. BE is believed to develop mainly from chronic GERD and is the most important risk factor of esophageal adenocarcinoma. Despite the availability of drugs such as proton pomp inhibitors and antacids, GERD is still a burden to local economy and impairs health-related quality of life in patients. Also, the endoscopic surveillance in patients with BE is burdensome and expensive what drives the need for biomarker of intestinal metaplasia and dysplasia. Trefoil factor family (TFF), consisting of TFF1, TFF2 and TFF3 peptides is gaining more and more attention due to its unique biochemical features and numerous functions. In this review the role of TFF1, TFF2 and TFF3 as potential treatment option and/or biomarker in the upper GI tract is discussed with particular focus on GERD and BE.

Intestinal epithelial potassium channels and CFTR chloride channels activated in ErbB tyrosine kinase inhibitor diarrhea

Diarrhea is a major side effect of ErbB receptor tyrosine kinase inhibitors (TKIs) in cancer chemotherapy. Here, we show that the primary mechanism of ErbB TKI diarrhea is activation of basolateral membrane potassium (K+) channels and apical membrane chloride (Cl-) channels in intestinal epithelia and demonstrate the efficacy of channel blockers in a rat model of TKI diarrhea. Short-circuit current in colonic epithelial cells showed that the TKIs gefitinib, lapatinib, and afatinib do not affect basal secretion but amplify carbachol-stimulated secretion by 2- to 3-fold. Mechanistic studies with the second-generation TKI afatinib showed that the amplifying effect on Cl- secretion was Ca2+ and cAMP independent, was blocked by CF transmembrane conductance regulator (CFTR) and K+ channel inhibitors, and involved EGFR binding and ERK signaling. Afatinib-amplified activation of basolateral K+ and apical Cl- channels was demonstrated by selective membrane permeabilization, ion substitution, and channel inhibitors. Rats that were administered afatinib orally at 60 mg/kg/day developed diarrhea with increased stool water from approximately 60% to greater than 80%, which was reduced by up to 75% by the K+ channel inhibitors clotrimazole or senicapoc or the CFTR inhibitor (R)-BPO-27. These results indicate a mechanism for TKI diarrhea involving K+ and Cl- channel activation and support the therapeutic efficacy of channel inhibitors.

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.

Paper-based microreactor array for rapid screening of cell signaling cascades

Investigation of cell signaling pathways is important for the study of pathogenesis of cancer. However, the related operations used in these studies are time consuming and labor intensive. Thus, the development of effective therapeutic strategies may be hampered. In this work, gel-free cell culture and subsequent immunoassay has been successfully integrated and conducted in a paper-based microreactor array. Study of the activation level of different kinases of cells stimulated by different conditions, i.e., IL-6 stimulation, starvation, and hypoxia, was demonstrated. Moreover, rapid screening of cell signaling cascades after the stimulations of HGF, doxorubicin, and UVB irradiation was respectively conducted to simultaneously screen 40 kinases and transcription factors. Activation of multi-signaling pathways could be identified and the correlation between signaling pathways was discussed to provide further information to investigate the entire signaling network. The present technique integrates most of the tedious operations using a single paper substrate, reduces sample and reagent consumption, and shortens the time required by the entire process. Therefore, it provides a first-tier rapid screening tool for the study of complicated signaling cascades. It is expected that the technique can be developed for routine protocol in conventional biological research laboratories.

Quantitative Study of Cell Invasion Process under Extracellular Stimulation of Cytokine in a Microfluidic Device

Cell invasion is the first step of cancer metastasis that is the primary cause of death for cancer patients and defined as cell movement through extracellular matrix (ECM). Investigation of the correlation between cell invasive and extracellular stimulation is critical for the inhabitation of metastatic dissemination. Conventional cell invasion assay is based on Boyden chamber assay, which has a number of limitations. In this work, a microfluidic device incorporating with impedance measurement technique was developed for quantitative investigation of cell invasion process. The device consisted of 2 reservoirs connecting with a microchannel filled with hydrogel. Malignant cells invaded along the microchannel and impedance measurement was concurrently conducted by measuring across electrodes located at the bottom of the microchannel. Therefore, cell invasion process could be monitored in real-time and non-invasive manner. Also, cell invasion rate was then calculated to study the correlation between cell invasion and extracellular stimulation, i.e., IL-6 cytokine. Results showed that cell invasion rate was directly proportional to the IL-6 concentration. The microfluidic device provides a reliable and convenient platform for cell-based assays to facilitate more quantitative assessments in cancer research.

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.

Trefoil Factor-3 (TFF3) Stimulates De Novo Angiogenesis in Mammary Carcinoma both Directly and Indirectly via IL-8/CXCR2

Mammary carcinoma cells produce pro-angiogenic factors to stimulate angiogenesis and tumor growth. Trefoil factor-3 (TFF3) is an oncogene secreted from mammary carcinoma cells and associated with poor prognosis. Herein, we demonstrate that TFF3 produced in mammary carcinoma cells functions as a promoter of tumor angiogenesis. Forced expression of TFF3 in mammary carcinoma cells promoted proliferation, survival, invasion and in vitro tubule formation of human umbilical vein endothelial cells (HUVEC). MCF7-TFF3 cells with forced expression of TFF3 generated tumors with enhanced microvessel density as compared to tumors formed by vector control cells. Depletion of TFF3 in mammary carcinoma cells by siRNA concordantly decreased the angiogenic behavior of HUVEC. Forced expression of TFF3 in mammary carcinoma cells stimulated IL-8 transcription and subsequently enhanced IL-8 expression in both mammary carcinoma cells and HUVEC. Depletion of IL-8 in mammary carcinoma cells with forced expression of TFF3, or antibody inhibition of IL-8, partially abrogated mammary carcinoma cell TFF3-stimulated HUVEC angiogenic behavior in vitro, as did inhibition of the IL-8 receptor, CXCR2. Depletion of STAT3 by siRNA in MCF-7 cells with forced expression of TFF3 partially diminished the angiogenic capability of TFF3 on stimulation of cellular processes of HUVEC. Exogenous recombinant hTFF3 also directly promoted the angiogenic behavior of HUVEC. Hence, TFF3 is a potent angiogenic factor and functions as a promoter of de novo angiogenesis in mammary carcinoma, which may co-coordinate with the growth promoting and metastatic actions of TFF3 in mammary carcinoma to enhance tumor progression.

Trefoils: An unexplored natural protective shield of oral cavity

The new mammalian growth factor peptide family consists of three peptides, TFF1, TFF2, and TFF3, which are secreted mainly from mucous epithelia with mucus gel. The predominant secretion of trefoil factor (TFF) occurs from gastric mucosal lining, small and large intestine, oral mucosal cells, and salivary glands. Research regarding trefoil factors is an immerging aspect in the dental field. The mucosal healing and restitution function describes about its novel role in case of chronic inflammatory conditions, but its expression from different tissue at different pathological condition shows its importance in immune response. At present, TFF expression has been detected from the severe periodontal diseased tissue samples. Future research from mild to moderate chronic periodontal diseased condition should be carried out to assess the protective response of TFF in gingival tissues. In future, assessment of TFF levels and its expression in oral mucosal tissues and oral secretions, such as saliva and gingival crevicular fluid, will provide a negative biomarker for chronic periodontal diseases and a novel therapeutic agent in oral mucosal healing.

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.

Quantitative impedimetric monitoring of cell migration under the stimulation of cytokine or anti-cancer drug in a microfluidic chip

Cell migration is a cellular response and results in various biological processes such as cancer metastasis, that is, the primary cause of death for cancer patients. Quantitative investigation of the correlation between cell migration and extracellular stimulation is essential for developing effective therapeutic strategies for controlling invasive cancer cells. The conventional method to determine cell migration rate based on comparison of successive images may not be an objective approach. In this work, a microfluidic chip embedded with measurement electrodes has been developed to quantitatively monitor the cell migration activity based on the impedimetric measurement technique. A no-damage wound was constructed by microfluidic phenomenon and cell migration activity under the stimulation of cytokine and an anti-cancer drug, i.e., interleukin-6 and doxorubicin, were, respectively, investigated. Impedance measurement was concurrently performed during the cell migration process. The impedance change was directly correlated to the cell migration activity; therefore, the migration rate could be calculated. In addition, a good match was found between impedance measurement and conventional imaging analysis. But the impedimetric measurement technique provides an objective and quantitative measurement. Based on our technique, cell migration rates were calculated to be 8.5, 19.1, and 34.9 μm/h under the stimulation of cytokine at concentrations of 0 (control), 5, and 10 ng/ml. This technique has high potential to be developed into a powerful analytical platform for cancer research.

TFF2-CXCR4 Axis Is Associated with BRAF V600E Colon Cancer

Oncogene-induced senescence (OIS), a tumor-suppressive mechanism that is induced by the replicative and metabolic stress of oncogene activation, is a key barrier in the development of BRAF V600E colon cancer. Inhibition of this mechanism has been observed through epigenetic changes observed in sporadic serrated polyps, as well as through the germline mutations associated with those who develop serrated polyposis. We hypothesize that upregulated autocrine factors exist that are specific to the serrated pathway and also promote bypass of oncogene-induced senescence. To identify such autocrine factors, we integrate analyses of microarrays of sessile serrated polyps and two large colon cancer cohorts, the Cancer Genome Atlas (TCGA; n = 153), and French national Cartes d'Identité des Tumeurs (CIT) program (n = 462), with enhanced gene annotation through natural language processing techniques of the existing medical corpus. We reproducibly associate higher expression of the ligand-receptor axis of TFF2 and CXCR4 with BRAF V600E-mutant colon cancer (P = 3.0 × 10(-3) and 0.077, respectively for TCGA; P = 3.0 × 10(-8) and 5.1 × 10(-7) for CIT). Given well-described oncogenic roles of TFF2 and CXCR4 in colon cancer, and availability of CXCR4 inhibitors for other clinical indications, this ligand-receptor axis may represent an actionable target for prevention and treatment of this molecular subtype of colorectal cancer.

Intestinal trefoil factor activates the PI3K/Akt signaling pathway to protect gastric mucosal epithelium from damage

Intestinal trefoil factor (ITF, also named as trefoil factor 3, TFF3) is a member of the TFF-domain peptide family, which plays an essential role in the regulation of cell survival, cell migration and maintains mucosal epithelial integrity in the gastrointestinal tract. However, the underlying mechanisms and associated molecules remain unclear. The aim of this study was to explore the protective effects of ITF on gastric mucosal epithelium injury and its possible molecular mechanisms of action. In the present study, we show that ITF was able to promote the proliferation and migration of GES-1 cells via a mechanism that involves the PI3K/Akt signaling pathway. Western blot results indicated that ITF induced a dose- and time-dependent increase in the Akt signaling pathway. ITF also plays an essential role in the restitution of GES-1 cell damage induced by lipopolysaccharide (LPS). LPS induced the apoptosis of GES-1 cells, decreased cell viability significantly (P<0.01) and led to epithelial tight junction damage, which is attenuated via ITF treatment. The protective effect of ITF on the integrity of GES-1 was abrogated by inhibition of the PI3K/Akt pathway. Taken together, our results demonstrate that ITF promotes the proliferation and migration of gastric mucosal epithelial cells and preserves gastric mucosal epithelial integrity after damage is mediated by activation of the PI3K/Akt signaling pathway. This study suggested that the PI3K/Akt pathway could act as a key intracellular pathway in the gastric mucosal epithelium that may serve as a therapeutic target to preserve epithelial integrity during injury.

Microarray gene expression analysis of the human airway in patients exposed to sulfur mustard

There is much data about the acute effects of sulfur mustard gas on humans, animals and cells. But less is known regarding the molecular basics of chronic complications in humans. Basically, mustard gas, as an alkylating agent, causes several chronic problems in the eyes, skin and more importantly in the pulmonary system which is the main cause of death. Although recent proteomic research has been carried out on bronchoalveolar lavage (BAL) and serum, but high-throughput transcriptomics have not yet been applied to chronic airway remodeling. This is the first cDNA-microarray report on the chronic human mustard lung disease, 25 years after exposure during the Iran-Iraq war. Microarray transcriptional profiling indicated that a total of 122 genes were significantly dysregulated in tissues located in the airway of patients. These genes are associated with the extracellular matrix components, apoptosis, stress response, inflammation and mucus secretion.

Serum trefoil factor 3 is a promising non-invasive biomarker for gastric cancer screening: a monocentric cohort study in China

BACKGROUND

The search for better non-invasive biomarkers for gastric cancer remains ongoing. We investigated the predictive power of serum trefoil factor (TFF) levels as biomarkers for gastric cancer in comparison with the pepsinogen (PG) test.

METHODS

Patients with gastric cancer, chronic atrophic gastritis (CAG) or chronic non-atrophic gastritis (CNAG), and healthy people were recruited. Serum concentrations of TFFs, PG I, and PG II, as well as the presence of antibodies against Helicobacter pylori, were measured by enzyme-linked immunosorbent assays (ELISA). Receiver operating characteristics (ROC) were used to compare the predictive powers of the selected factors.

RESULTS

The serum concentrations of TFF1, TFF2, and TFF3 in the control groups were significantly lower than those in the gastric cancer group with the exception of TFF2 which was elevated in CAG. The area under the ROC curve for TFF3 was greater than that for the PG I/II ratio (0.81 vs 0.78). TFF3 also had a significantly higher predictive power for distinguishing gastric cancer than the PG test (odds ratio: 10.33 vs 2.57). Moreover, combining the serum TFF3 and PG tests for gastric cancer had better predictive power than either alone.

CONCLUSIONS

Serum TFF3 may be a better predictor of gastric cancer than the PG test, while the combined testing of serum PG and TFF3 could further improve the efficacy of gastric cancer screening.

Perilla frutescens leaf extract inhibits mite major allergen Der p 2-induced gene expression of pro-allergic and pro-inflammatory cytokines in human bronchial epithelial cell BEAS-2B

Perilla frutescens has been used in traditional medicine for respiratory diseases due to its anti-bacterial and anti-inflammatory activity. This study aimed to investigate effects of Perilla frutescens leaf extract (PFE) on expression of pro-allergic and pro-inflammatory cytokines in airway epithelial cells exposed to mite major allergen Der p 2 (DP2) and the underlying mechanisms. Our results showed that PFE up to 100 µg/mL had no cytotoxic effect on human bronchial epithelial cell BEAS-2B. Further investigations revealed that PFE dose-dependently diminished mRNA expression of pro-allergic cytokine IL-4, IL-5, IL-13 and GM-CSF, as well as pro-inflammatory cytokine IL-6, IL-8 and MCP-1 in BEAS-2B cells treated with DP2. In parallel to mRNA, the DP-2-elevated levels of the tested cytokines were decreased. Further investigation showed that DP2-indued phosphorylation of p38 MAPK (P38) and JNK, but not Erk1/2, was also suppressed by PFE. In addition, PFE elevated cytosolic IκBα level and decreased nuclear NF-κB level in DP2-stimulated BEAS-2B cells. Taken together, these findings revealed that PFE significantly diminished both mRNA expression and protein levels of pro-allergic and pro-inflammatory cytokines in response to DP2 through inhibition of P38/JNK and NK-κB activation. These findings suggest that PFE should be beneficial to alleviate both allergic and inflammatory responses on airway epithelium in response to aeroallergens.

Promoter polymorphisms in trefoil factor 2 and trefoil factor 3 genes and susceptibility to gastric cancer and atrophic gastritis among Chinese population

The polymorphisms in trefoil factor (TFF) gene family that protect gastrointestinal epithelium might influence individual vulnerability to gastric cancer (GC) and atrophic gastritis. We used the Sequenom MassARRAY platform to identify the genotypes of TFF2 rs3814896 and TFF3 rs9981660 polymorphisms in 478 GC patients, 652 atrophic gastritis patients, and 724 controls. For the TFF2 rs3814896 polymorphism, in the subgroup aged ≤ 50 years, we found that AG+GG genotypes were associated with a 0.746-fold decreased risk of atrophic gastritis [p=0.023, 95% confidence interval (CI)=0.580-0.960], a 0.626-fold decreased risk of GC (p=0.005, 95% CI=0.451-0.868), and a 0.663-fold decreased risk of diffuse-type GC (p=0.034, 95% CI=0.452-0.970) compared with the common AA genotype. For the TFF3 rs9981660 polymorphism, in the male subgroup, individuals with variant AG+AA genotype were associated with a 0.761-fold decreased risk of diffuse-type GC compared with the common GG genotype (p=0.043, 95% CI=0.584-0.992). Additionally, we found that in subjects aged ≤ 50 years compared with common AA genotype, TFF2 rs3814896 AG+GG genotypes were associated with increased TFF2 mRNA levels in the total gastric cancer specimens and in the diffuse-type gastric cancer specimens; and in males aged ≤ 50 years compared with common GG genotype, TFF3 rs9981660 AA+AG genotypes were associated with TFF3 mRNA levels in diffuse-type gastric cancer tissues and their corresponding non-cancerous tissues. To our knowledge, this is the first report of an association between the TFF2 rs3814896 AG+GG genotypes and decreased risks of GC, diffuse-type GC, and atrophic gastritis in younger people aged ≤ 50 years, and an association between TFF3 rs9981660 AG+AA genotype and decreased risk of diffuse-type GC in men. Moreover, we found that TFF2 rs3814896 AG+GG genotypes in people aged ≤ 50 years and TFF3 rs9981660 AG+AA genotypes in younger males with diffuse-type GC were associated with higher levels of TFF2 and TFF3 mRNA respectively.

Trefoil factor 2 promotes cell proliferation in pancreatic β-cells through CXCR-4-mediated ERK1/2 phosphorylation

Decreased β-cell mass is a hallmark of type 2 diabetes, and therapeutic approaches to increase the pancreatic β-cell mass have been expected. In recent years, gastrointestinal incretin peptides have been shown to exert a cell-proliferative effect in pancreatic β-cells. Trefoil factor 2 (TFF2), which is predominantly expressed in the surface epithelium of the stomach, plays a role in antiapoptosis, migration, and proliferation. The TFF family is expressed in pancreatic β-cells, whereas the role of TFF2 in pancreatic β-cells has been obscure. In this study, we investigated the mechanism by which TFF2 enhances pancreatic β-cell proliferation. The effects of TFF2 on cell proliferation were evaluated in INS-1 cells, MIN6 cells, and mouse islets using an adenovirus vector containing TFF2 or a recombinant TFF2 peptide. The forced expression of TFF2 led to an increase in bromodeoxyuridine (BrdU) incorporation in both INS-1 cells and islets, without any alteration in insulin secretion. TFF2 significantly increased the mRNA expression of cyclin A2, D1, D2, D3, and E1 in islets. TFF2 peptide increased ERK1/2 phosphorylation and BrdU incorporation in MIN6 cells. A MAPK kinase inhibitor (U0126) abrogated the TFF2 peptide-mediated proliferation of MIN6 cells. A CX-chemokine receptor-4 antagonist also prevented the TFF2 peptide-mediated increase in ERK1/2 phosphorylation and BrdU incorporation in MIN6 cells. These results indicated that TFF2 is involved in β-cell proliferation at least partially via CX-chemokine receptor-4-mediated ERK1/2 phosphorylation, suggesting TFF2 may be a novel target for inducing β-cell proliferation.

Regulation of interleukin-6 secretion by the two-pore-domain potassium channel Trek-1 in alveolar epithelial cells

We recently proposed a role for the two-pore-domain K(+) (K2P) channel Trek-1 in the regulation of cytokine release from mouse alveolar epithelial cells (AECs) by demonstrating decreased interleukin-6 (IL-6) secretion from Trek-1-deficient cells, but the underlying mechanisms remained unknown. This study was designed to investigate the mechanisms by which Trek-1 decreases IL-6 secretion. We hypothesized that Trek-1 regulates tumor necrosis factor-α (TNF-α)-induced IL-6 release via NF-κB-, p38-, and PKC-dependent pathways. We found that Trek-1 deficiency decreased IL-6 secretion from mouse and human AECs at both transcriptional and translational levels. While NF-κB/p65 phosphorylation was unchanged, p38 phosphorylation was decreased in Trek-1-deficient cells, and pharmacological inhibition of p38 decreased IL-6 secretion in control but not Trek-1-deficient cells. Similarly, pharmacological inhibition of PKC also decreased IL-6 release, and we found decreased phosphorylation of the isoforms PKC/PKDμ (Ser(744/748)), PKCθ, PKCδ, PKCα/βII, and PKCζ/λ, but not PKC/PKDμ (Ser(916)) in Trek-1-deficient AECs. Phosphorylation of PKCθ, a Ca(2+)-independent isoform, was intact in control cells but impaired in Trek-1-deficient cells. Furthermore, TNF-α did not elevate the intracellular Ca(2+) concentration in control or Trek-1-deficient cells, and removal of extracellular Ca(2+) did not impair IL-6 release. In summary, we report the expression of Trek-1 in human AECs and propose that Trek-1 deficiency may alter both IL-6 translation and transcription in AECs without affecting Ca(2+) signaling. The results of this study identify Trek-1 as a new potential target for the development of novel treatment strategies against acute lung injury.

Knowledge translation: airway epithelial cell migration and respiratory diseases

Airway epithelial cell migration is essential for lung development and growth, as well as the maintenance of respiratory tissue integrity. This vital cellular process is also important for the repair and regeneration of damaged airway epithelium. More importantly, several lung diseases characterized by aberrant tissue remodeling result from the improper repair of damaged respiratory tissue. Epithelial cell migration relies upon extracellular matrix molecules and is further regulated by numerous local, neuronal, and hormonal factors. Under inflammatory conditions, cell migration can also be stimulated by certain cytokines and chemokines. Many well-known environmental factors involved in the pathogenesis of chronic lung diseases (e.g., cigarette smoking, air pollution, alcohol intake, inflammation, viral and bacterial infections) can inhibit airway epithelial cell migration. Further investigation of cellular and molecular mechanisms of cell migration with advanced techniques may provide knowledge that is relevant to physiological and pathological conditions. These studies may eventually lead to the development of therapeutic interventions to improve lung repair and regeneration and to prevent aberrant remodeling in the lung.

Increased trefoil factor 3 levels in the serum of patients with three major histological subtypes of lung cancer

Lung cancer is the most common cause of cancer-related deaths in the world. The trefoil factor (TFF) family is composed of three thermostable, and protease-resistant proteins, named TFF1, TFF2 and TFF3. TFF protein levels have been found to be related to the development of various types of cancer. However, it is still unclear whether TFF proteins are differentially expressed in the serum of different histological subtypes of lung cancer compared to healthy individuals. In this study, we investigated the levels of TFF proteins in serum and lung tissues of 130 lung cancer patients (58 squamous cell lung carcinoma cases, 43 adenocarcinoma cases and 29 SCLC cases) and 60 healthy individuals. It was found that TFF1 and TFF2 have similar or slightly higher levels in these three subtypes of lung cancer compared to healthy individuals, while TFF3 levels were significantly higher in the examined lung cancer cases compared to healthy individuals. Immunoblot analyses of TFF1, TFF2 and TFF3 indicated that lung cancer tissues and lung cancer cell lines have a higher expression of the TFF3 protein, but not of TFF1 or TFF2 proteins, compared to tissues from healthy individuals or from the normal cell line. Quantitative RT-PCR analysis indicated higher levels of TFF3, but not TFF1 and TFF2, transcripts in lung cancer tissues or cell lines. These results show increased TFF3 levels in serum and lung tissues, suggesting that TFF3 may serve as a promising, easily detected biomarker of lung cancer.

Trefoil factor family peptide 2 acts pro-proliferative and pro-apoptotic in the murine retina

Although expression of trefoil factor family (TFF) peptides has been reported in the brain, nothing is known about TFF expression in the retina. The aim of this study was to test whether TFF peptides are expressed in the murine retina and have any function here. In contrast to most tissues studied, where TFF1 and TFF3 are the predominant peptides, TFF2 is the only peptide expressed in the murine retina. Immunohistochemical studies on murine retinal sections indicate that cells of the ganglion cell layer are the retinal source for murine TFF2 (Tff2). In organotypic murine retina cell cultures recombinant TFF2 exerted a strong pro-apoptotic and pro-proliferative rather than an anti-apoptotic and anti-proliferating effect described in most human cancer cell lines investigated so far. In blockage experiments we were able to demonstrate that the pro-apoptotic effect of TFF2 is caspase-dependent. Western blot analysis of TFF2 treated retinal wholemount homogenates revealed significant reductions in the phosphorylation level of ERK and STAT3 proteins compared to basal conditions, suggesting that in the developing murine retina survival mechanism are down-regulated upon TFF2 administration. Our results suggest that during retinal cell death periods, requiring a tightly regulated balance between cell survival and cell death, TFF2 acts pro-proliferative and pro-apoptotic at least in developing mouse retinae cultured in vivo.

Enhancement of wound healing by human multipotent stromal cell conditioned medium: the paracrine factors and p38 MAPK activation

Wound healing can be improved by transplanting mesenchymal stem cells (MSCs). In this study, we have demonstrated the benefits of the conditioned medium derived from human MSCs (CM-MSC) in wound healing using an excisional wound model. CM-MSC accelerated wound closure with increased reepithelialization, cell infiltration, granulation formation, and angiogenesis. Notably, CM-MSC enhanced epithelial and endothelial cell migration, suggesting the contribution of increased cell migration to wound healing enhanced by CM-MSC. Cytokine array, ELISA analysis, and quantitative RT-PCR revealed high levels of IL-6 in CM-MSC. Moreover, IL-6 added to the preconditioned medium enhanced both cell migration and wound healing, and antibodies against IL-6 blocked the increase in cell motility and wound closure by CM-MSC. The IL-6 secretory pathway of MSCs was inhibited by SB203580, an inhibitor of p38 MAPK or siRNA against p38 MAPK, suggesting IL-6 secretion by MSCs is mediated through the activation of p38 MAPK. Inactivation of p38 MAPK also reduced the expression and production of IL-8 and CXCL1 by MSCs, both of which were also demonstrated to enhance cell migration and wound closure. Thus, our data suggest MSCs promote wound healing through releasing a repertoire of paracrine factors via activation of p38 MAPK, and the CM-MSC may be applied to enhance wound healing.

Human intestinal TFF3 forms disulfide-linked heteromers with the mucus-associated FCGBP protein and is released by hydrogen sulfide

TFF3 is a secretory peptide belonging to the trefoil factor family with a predicted size of 59 amino acid residues containing seven cysteine residues. It is predominantly expressed in intestinal goblet cells where it plays a key role in mucosal regeneration and repair processes. In the course of these studies, human colonic TFF3 was shown to exist mainly as a high molecular weight heteromer. Purification of this heteromer and characterization by LC-ESI-MS/MS analysis identified the IgG Fc binding protein (FCGBP) as the disulfide-linked partner protein of TFF3. FCGBP is a constituent of intestinal mucus secreted by goblet cells. Furthermore, low amounts of TFF3/monomer and only little TFF3/dimer were detected in human colonic extracts. Here, we show that these TFF3 forms can be released from the purified TFF3-FCGBP heteromer complex in vitro by reduction with hydrogen sulfide (H(2)S). Such a mechanism would be in line with the high H(2)S concentrations reported to occur in the lumen of the colon. Of special note, this points to intestinal mucus as a reservoir for a biologically active peptide. Also proteolytic processing of FCGBP was observed which is in line with multiple autocatalytic cleavages as proposed earlier by Johansson et al. (J. Proteome Res. 2009 , 8 , 3549 - 3557).

Polarized secretion of interleukin (IL)-6 and IL-8 by human airway epithelia 16HBE14o- cells in response to cationic polypeptide challenge

BACKGROUND

The airway epithelium participates in asthmatic inflammation in many ways. Target cells of the epithelium can respond to a variety of inflammatory mediators and cytokines. Damage to the surface epithelium occurs following the secretion of eosinophil-derived, highly toxic cationic proteins. Moreover, the surface epithelium itself is responsible for the synthesis and release of cytokines that cause the selective recruitment, retention, and accumulation of various inflammatory cells. To mimic the damage seen during asthmatic inflammation, the bronchial epithelium can be challenged with highly charged cationic polypeptides such as poly-L-arginine.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, human bronchial epithelial cells, 16HBE14o- cells, were "chemically injured" by exposing them to poly-l-arginine as a surrogate of the eosinophil cationic protein. Cytokine antibody array data showed that seven inflammatory mediators were elevated out of the 40 tested, including marked elevation in interleukin (IL)-6 and IL-8 secretion. IL-6 and IL-8 mRNA expression levels were elevated as measured with real-time PCR. Cell culture supernatants from apical and basolateral compartments were collected, and the IL-6 and IL-8 production was quantified with ELISA. IL-6 and IL-8 secretion by 16HBE14o- epithelia into the apical compartment was significantly higher than that from the basolateral compartment. Using specific inhibitors, the production of IL-6 and IL-8 was found to be dependent on p38 MAPK, ERK1/2 MAPK, and NF-kappaB pathways.

CONCLUSIONS/SIGNIFICANCE

The results clearly demonstrate that damage to the bronchial epithelia by poly-L-arginine stimulates polarized IL-6 and IL-8 secretion. This apically directed secretion of cytokines may play an important role in orchestrating epithelial cell responses to inflammation.

Synthesis and localization of trefoil factor family (TFF) peptides in the human urinary tract and TFF2 excretion into the urine

Trefoil factor family (TFF) peptides promote regeneration and repair processes of mucous epithelia. They also probably play a key role in the remarkable regenerative capacity of the urinary tract epithelia. We have localized TFF1, TFF2, and TFF3 expression systematically in surgical specimens from the urinary tract by reverse transcription with the polymerase chain reaction, Western blot analysis, and immunohistochemistry. Urine samples from patients suffering from nephrolithiasis have been investigated and compared with those of healthy controls. TFF synthesis is detectable along the entire urinary tract epithelia. TFF3 synthesis is the most pronounced followed by TFF1, whereas TFF2 synthesis is occasionally detectable but only in trace amounts. In contrast, TFF2 is the predominant TFF peptide excreted into the urine, and significantly increased urinary TFF2 levels (together with occasionally raised TFF3 levels) have been observed in patients suffering from nephrolithiasis. Thus, we consider that TFF3 plays a major part in regeneration and restitution processes in urinary tract epithelia. TFF2 and probably also TFF3 are candidate biomarkers for nephrolithiasis and possibly other inflammatory conditions of the urinary tract.

[Trefoil factor: from laboratory to clinic]

Trefoil factor (TFF) family is a group of peptides with one or several trefoil factor domains in their structure, which are highly conserved in evolution, and are characterized by heat and enzymatic digestion resistance. The mammalian TFFs have three members (TFF1-3), and the gastrointestinal tract and the airway system are major organs of their expression and secretion. At certain physiological conditions, with a tissue-specific distribution, TFF plays an important role in mucosal protection and wound healing. But in the malignant tissues, TFF is widely expressed, correlated strongly with the genesis, metastasis and invasion of tumor cells. These phenomena indicated that TFF may be a possible common mediator of oncogenic responses to different stimuli. The biological functions of TFF involve complex regulatory processes. Single chain TFF may activate cell membrane receptors and induce specific signaling transduction. On the other hand, TFF can form a complex with other proteins to exert its biological effects. In clinical medicine, TFF is primarily applied as drugs in the mucosal protection, in the prevention and the treatment of mucosal damage-related diseases and as pathological biomarkers of tumors. At present the first hand actions and the molecular mechanisms related to TFFs are still the major challenges in TFF research. Furthermore, the discovery of the naturally occurring complex of TFF and crystallins is highly valuable to the understanding of the biological functions and action mechanisms of TFF.

Human intestinal MUC17 mucin augments intestinal cell restitution and enhances healing of experimental colitis

The membrane-bound mucins, MUC17 (human) and Muc3 (mouse), are highly expressed on the apical surface of intestinal epithelia and are thought to be cytoprotective. The extracellular regions of these mucins contain EGF-like Cys-rich segments (CRD1 and CRD2) connected by an intervening linker domain (L). The purpose of this study was to determine the functional activity of human MUC17 membrane-bound mucin.

METHODS

Endogenous MUC17 was inhibited in LS174T colon cells by stable transfection of a small hairpin RNA targeting MUC17 (LSsi cells). The effect of recombinant MUC17-CRD1-L-CRD2 protein on migration, apoptosis, and experimental colitis was determined.

RESULTS

Reduced MUC17 expression in LSsi cells was associated with visibly reduced cell aggregation, reduced cell-cell adherence, and reduced cell migration, but no change in tumorigenicity. LSsi cells also demonstrated a 3.7-fold increase in apoptosis rates compared with control cells following treatment with etoposide. Exposure of colonic cell lines to exogenous recombinant MUC17-CRD1-L-CRD2 protein significantly increased cell migration and inhibited apoptosis. As a marker of biologic activity, MUC17-CRD1-L-CRD2 proteins stimulate ERK phosphorylation in colonic cell lines; and inhibition of ERK phosphorylation reduced the anti-apoptosis and migratory effect of MUC17-CRD1-L-CRD2. Finally, mice treated with MUC17-CRD1-L-CRD2 protein given per rectum demonstrated accelerated healing in acetic acid and dextran sodium sulfate induced colitis in vivo. These data indicate that both native MUC17 and the exogenous recombinant cysteine-rich domain of MUC17 play a role in diverse cellular mechanisms related to cell restitution, and suggest a potential role for MUC17-CRD1-L-CRD2 recombinant protein in the treatment of mucosal inflammatory diseases.

Signal transduction and gene transcription induced by TFF3 in oral keratinocytes

Trefoil factor family 3 (TFF3) is secreted in saliva. The peptide improves the mechanical and chemical resistance of mucins, and it may act as a motility signal for oral keratinocytes during wound healing. This study aimed to identify novel functions of TFF3 in oral keratinocytes. To achieve this, we used phosphoprotein and messenger RNA (mRNA) arrays to compare TFF3-treated and untreated oral keratinocytes. Analysis of the phosphoprotein array indicated that TFF3 signals through the mitogen-activated protein kinases (MAPKs) c-Jun N-terminal kinase (JNK), p38, and extracellular signal-regulated kinase (ERK1/2), and through the phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB) pathway. Microarray analysis of mRNA showed that TFF3 stimulation induced changes in the expression of genes functionally related to cell death/survival, cell growth and proliferation, and cell movement. The reverse transcription-polymerase chain reaction (RT-PCR) results indicated that the transcription of some immediate-early genes (IEGs) was downregulated, whereas the IEGs FBJ osteosarkoma oncogene (FOS) and C-MYC binding protein (MYCBP2) were transiently upregulated by TFF3 stimulation. Together, the results of the arrays indicate that TFF3 is a modifying factor in pathways regulating cell survival, cell growth and proliferation, and cell migration of oral keratinocytes. Trefoil factor family 3 may therefore promote oral wound healing and it should be considered for the treatment of oral ulcerating diseases, or of other diseases.

Secreted trefoil factor 2 activates the CXCR4 receptor in epithelial and lymphocytic cancer cell lines

The secreted trefoil factor family 2 (TFF2) protein contributes to the protection of the gastrointestinal mucosa from injury by strengthening and stabilizing mucin gels, stimulating epithelial restitution, and restraining the associated inflammation. Although trefoil factors have been shown to activate signaling pathways, no cell surface receptor has been directly linked to trefoil peptide signaling. Here we demonstrate the ability of TFF2 peptide to activate signaling via the CXCR4 chemokine receptor in cancer cell lines. We found that both mouse and human TFF2 proteins (at approximately 0.5 microm) activate Ca2+ signaling in lymphoblastic Jurkat cells that could be abrogated by receptor desensitization (with SDF-1alpha) or pretreatment with the specific antagonist AMD3100 or an anti-CXCR4 antibody. TFF2 pretreatment of Jurkat cells decreased Ca2+ rise and chemotactic response to SDF-1alpha. In addition, the CXCR4-negative gastric epithelial cell line AGS became highly responsive to TFF2 treatment upon expression of the CXCR4 receptor. TFF2-induced activation of mitogen-activated protein kinases in gastric and pancreatic cancer cells, KATO III and AsPC-1, respectively, was also dependent on the presence of the CXCR4 receptor. Finally we demonstrate a distinct proliferative effect of TFF2 protein on an AGS gastric cancer cell line that expresses CXCR4. Overall these data identify CXCR4 as a bona fide signaling receptor for TFF2 and suggest a mechanism through which TFF2 may modulate immune and tumorigenic responses in vivo.

Repetitive deformation activates Src-independent FAK-dependent ERK motogenic signals in human Caco-2 intestinal epithelial cells

Repetitive deformation due to villous motility or peristalsis may support the intestinal mucosa, stimulating intestinal epithelial proliferation under normal circumstances and restitution in injured and inflamed mucosa rich in tissue fibronectin. Cyclic strain enhances Caco-2 and IEC-6 intestinal epithelial cell migration across fibronectin via ERK. However, the upstream mediators of ERK activation are unknown. We investigated whether Src and FAK mediate strain-induced ERK phosphorylation and migration in human Caco-2 intestinal epithelial cells on fibronectin. Monolayers on tissue fibronectin-precoated membranes were subjected to an average 10% repetitive deformation at 10 cycles/min. Phosphorylation of Src-Tyr 418, FAK-Tyr 397-Tyr 576-Tyr 925, and ERK were significantly increased by deformation. The stimulation of wound closure by strain was prevented by Src blockade with PP2 (10 micromol/l) or specific short interfering (si)RNA. Src inhibition also prevented strain-induced FAK phosphorylation at Tyr 397 and Tyr 576 but not FAK-Tyr 925 or ERK phosphorylation. Reducing FAK by siRNA inhibited strain-induced ERK phosphorylation. Transfection of NH2-terminal tyrosine phosphorylation-deficient FAK mutants Y397F, Y576F-Y577F, and Y397F-Y576F-Y577F did not prevent the activation of ERK2 by cyclic strain, but a FAK mutant at the COOH terminal (Y925F) prevented the strain-induced activation of ERK2. Although the Y397F-Y576F-Y577F FAK construct exhibited less basal FAK-Tyr 925 phosphorylation under static conditions, it nevertheless exhibited increased FAK-Tyr 925 phosphorylation in response to strain. These results suggest that repetitive deformation stimulates intestinal epithelial motility across fibronectin in a manner that requires both Src activation and a novel Src-independent FAK-Tyr 925-dependent pathway that activates ERK. This pathway may be an important target for interventions to promote mucosal healing in settings of intestinal ileus or fasting.

Are trefoil factors oncogenic?

Trefoil factors (TFFs), in particular TFF1, are classical estrogen-regulated genes and have served as markers of estrogen gene regulation by various environmental estrogens. TFFs are also regulated by several other factors including growth hormone (hGH), insulin-like growth factor-1 (IGF-1), epidermal growth factor (EGF) and various oncogenic stimuli. TFFs are secreted proteins present in serum and possess the potential to act as growth factors promoting cell survival, anchorage-independent growth and motility. Recent compelling evidence has emerged from experimental and clinical studies to indicate a pivotal role of TFFs in oncogenic transformation, growth and metastatic extension of common human solid tumours. This review will summarize the current evidence for the involvement of TFFs in human cancer.

TFF3 and EGF induce different migration patterns of intestinal epithelial cells in vitro and trigger increased internalization of E-cadherin

BACKGROUND/AIMS

TFF3, a member of the TFF (trefoil factor family) peptides, and epidermal growth factor (EGF) actively support the repair of mucosal barriers, particularly during restitution. The aim of this study was to compare the motogenic effects of TFF3 and EGF.

METHODS

The influence of recombinant human TFF3 (dimeric form) and EGF on the migration of IEC-18 cells was characterized in an in vitro restitution model (scratch wound assay) with the help of time-lapse video microscopy, morphometry, and immunocytochemistry including confocal laser scanning microscopy.

RESULTS

TFF3- and EGF-treated cells re-populated the wounded area via different migration patterns; TFF3 treatment resulted in the formation of continuous sheets of migrating cells with only a few gaps. In contrast, EGF-treated cells formed a network of migrating cells (often with a fibroblast-like morphology) with numerous gaps and only punctual contacts. TFF3 and EGF treatment also changed the localization of E-cadherin indicating endocytotic recycling and/or degradation of E-cadherin.

CONCLUSION

TFF3, in contrast to EGF, enhanced a collective cell migration ensuring a precise coverage of the re-populated area avoiding gaps.

Effect of active smoking on the human bronchial epithelium transcriptome

Background

Lung cancer is the most common cause of cancer-related deaths. Tobacco smoke exposure is the strongest aetiological factor associated with lung cancer. In this study, using serial analysis of gene expression (SAGE), we comprehensively examined the effect of active smoking by comparing the transcriptomes of clinical specimens obtained from current, former and never smokers, and identified genes showing both reversible and irreversible expression changes upon smoking cessation.

Results

Twenty-four SAGE profiles of the bronchial epithelium of eight current, twelve former and four never smokers were generated and analyzed. In total, 3,111,471 SAGE tags representing over 110 thousand potentially unique transcripts were generated, comprising the largest human SAGE study to date. We identified 1,733 constitutively expressed genes in current, former and never smoker transcriptomes. We have also identified both reversible and irreversible gene expression changes upon cessation of smoking; reversible changes were frequently associated with either xenobiotic metabolism, nucleotide metabolism or mucus secretion. Increased expression of TFF3, CABYR, and ENTPD8 were found to be reversible upon smoking cessation. Expression of GSK3B, which regulates COX2 expression, was irreversibly decreased. MUC5AC expression was only partially reversed. Validation of select genes was performed using quantitative RT-PCR on a secondary cohort of nine current smokers, seven former smokers and six never smokers.

Conclusion

Expression levels of some of the genes related to tobacco smoking return to levels similar to never smokers upon cessation of smoking, while expression of others appears to be permanently altered despite prolonged smoking cessation. These irreversible changes may account for the persistent lung cancer risk despite smoking cessation.

The importance of fibroblasts in remodelling of the human uterine cervix during pregnancy and parturition

It is well established that fibroblasts play a crucial role in pathophysiological extracellular matrix remodelling. The aim of this project is to elucidate their role in normal physiological remodelling. Specifically, the remodelling of the human cervix during pregnancy, resulting in an enabled passage of the child, is used as the model system. Fibroblast cultures were established from cervices of non-pregnant women, women after 36 weeks of pregnancy and women directly after partus. The cells were immunostained and quantified by western blots for differentiation markers. The cultures were screened for cytokine and metalloproteinase production and characterized by global proteome analysis. The cell cultures established from partal donors differ significantly from those from non-pregnant donors, which is in accordance with in vivo findings. A decrease in alpha-smooth actin and prolyl-4-hydroxylase and an increase in interleukin (IL)-6, IL-8 and matrix metalloproteinases (MMP)-1 and MMP-3 were observed in cultures from partal donors. 2D-gel electrophoresis followed by mass spectrometry showed that the expression of 59 proteins was changed significantly in cultures of partal donors. The regulated proteins are involved in protein kinase C signalling, Ca2+ binding, cytoskeletal organization, angiogenesis and degradation. Our data suggest that remodelling of the human cervix is orchestrated by fibroblasts, which are activated or recruited by the inflammatory processes occurring during the ripening cascade.