Induction and regulation of Smad7 in the gastric mucosa of patients with Helicobacter pylori infection

doi:10.1053/j.gastro.2003.11.048

Gastroenterology

Volume 126, Issue 3, March 2004, Pages 674-682

https://doi.org/10.1053/j.gastro.2003.11.048 Get rights and content

Abstract

$Background & Aims$ : Helicobacter pylori (Hp) infection causes a chronic gastric inflammation, which can lead to peptic ulceration and cancer. The inflammatory response is multifactorial and is characterized by exaggerated Th1 cytokine production. How the Th1 response is induced and maintained in the stomach of Hp-infected patients remains unclear. Transforming growth factor (TGF)-β1 negatively regulates Th1 cell development, and TGF-β1-deficient mice spontaneously develop gastritis. Here, we examined TGF-β1 signaling in Hp-associated gastritis. $Methods$ :Gastric biopsy specimens taken from patients with or without Hp infection were analyzed for the content of activated TGF-β1 by ELISA and Smad3 and 7 expression by Western blotting. Induction of Smad7 by interferon (IFN)-γ was examined in normal gastric mucosal biopsy specimens, whereas the effect of Smad7 inhibition on the ongoing Th1 response was analyzed in Hp-colonized biopsy specimens. $Results$ :Activated TGF-β1 was abundant in the mucosa of controls and Hp-infected patients, with no significant difference between the 2 groups. Despite this, in whole biopsy specimens and isolated mucosal cells from Hp-infected patients, there was defective TGF-β1-associated Smad3 phosphorylation, which was associated with high expression of the inhibitor Smad7. Blocking Smad7 with antisense oligonucleotides restored TGF-β1 signaling in biopsy specimens from Hp-infected patients and concomitantly reduced interferon-γ and T-bet. Smad7 was inducible in normal gastric biopsy specimens by interferon-γ through a STAT1-dependent mechanism, and neutralization of interferon-γ in biopsy specimens from Hp-infected patients reduced Smad7 expression. $Conclusions$ :These data suggest that, in Hp-infected gastric mucosa, interferon-γ induces the expression of Smad7, which then prevents endogenous TGF-β1 from down-regulating the ongoing tissue-damaging Th1 response.

Section snippets

Patients and sampling

Sixty-five patients (33 men and 32 women; median age, 49 years; range, 21–74 years) who underwent esophagogastroduodenoscopy for dyspeptic symptoms were studied. Thirty-three patients had Hp infection as confirmed by urease quick test and histology. Five Hp-infected patients were reendoscoped 2 months after cessation of 1-week treatment with omeprazole (20 mg twice daily), amoxycillin (1000 mg twice daily), and clarithromycin (500 mg twice daily). All these 5 patients were cured of Hp infection

Activated TGF-β1 is produced in the human gastric mucosa

TGF-β1 negatively regulates mucosal immune responses, and defects in TGF-β1 production have been associated with the development of gastritis in experimental models.9, 10, 11, 12 Therefore, we first sought to analyze whether the Hp-related gastritis associates with changes in the local concentrations of activated TGF-β1. Because several gastric mucosal cell types have the potential to synthesize TGF-β1, the cytokine was measured in total proteins extracted from whole gastric mucosa rather than

Discussion

In this study, we show that colonization of the stomach with Hp leads to a reduction in Smad3 phosphorylation, a crucial step in the TGF-β1-mediated signal transduction, despite the synthesis of active TGF-β1. The failure in TGF-β1 signaling is associated with high expression of Smad7, an inhibitor of TGF-β1-associated Smad3 phosphorylation. In contrast, abundant phosphorylated Smad3 is seen in the normal gastric mucosa, consistent with constitutively active TGF-β1 signaling.

TGF-β1 is one of

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Citation Excerpt :
Colonising more than half the global population, H. pylori is linked with gastritis, intestinal metaplasia, and gastric carcinoma (Monteleone et al., 2004; Shuang et al., 2015). H. pylori infection of gastric epithelial cells results in activation of NFκB, secretion of IL-8, and a localised Th1 response with increased expression of IL-12, TNF-α and IFN-γ (Monteleone et al., 2004; Shuang et al., 2015). Since TGF-β is an antagonist to Th1 responses, SMAD7 overexpression is a potential mechanism by which TGF-β signalling is attenuated and its anti-inflammatory effects ablated during H. pylori infection (Fig. 3).
Understanding the relationship between host and pathogen is key to combatting disease. SMAD transcription factors, which transmit TGF-β superfamily signalling, mediate an array of outcomes during embryogenesis, inflammation, cancer, and immunity. Surprisingly, these activities can sometimes be directly opposed; for example, SMAD3 has been reported as tumour suppressor by arresting cell cycle progression but conversely promotes cancer metastasis. A growing body of literature has identified SMADs as prominent targets during viral and bacterial infection for modulating host signalling. During infection, the activity of SMAD-containing transcriptional complexes can be finely tuned by pathogens to enhance infectivity and spread. SMAD signalling can be modulated at many levels, such as upstream at the ligand and receptor, or by direct interactions with SMADs. These alterations can increase pathogen dissemination, induce fibrosis, over-activate, or attenuate the host immune response. Here, we summarise the diverse mechanisms by which pathogens have evolved to sway SMAD signalling in their favour. Understanding the intricacies of host–pathogen interactions through this lens may elucidate aspects of SMAD function in cancer development, homoeostasis, and immune signalling previously overlooked. These insights are an opportunity to identify novel TGF-β or BMP-targeted therapeutics for applications to infectious disease contexts.
TGF-β Signaling in Liver, Pancreas, and Gastrointestinal Diseases and Cancer
2021, Gastroenterology
Genetic alterations affecting transforming growth factor–β (TGF-β) signaling are exceptionally common in diseases and cancers of the gastrointestinal system. As a regulator of tissue renewal, TGF-β signaling and the downstream SMAD-dependent transcriptional events play complex roles in the transition from a noncancerous disease state to cancer in the gastrointestinal tract, liver, and pancreas. Furthermore, this pathway also regulates the stromal cells and the immune system, which may contribute to evasion of the tumors from immune-mediated elimination. Here, we review the involvement of the TGF-β pathway mediated by the transcriptional regulators SMADs in disease progression to cancer in the digestive system. The review integrates human genomic studies with animal models that provide clues toward understanding and managing the complexity of the pathway in disease and cancer.
Orphan nuclear receptor Nurr1 promotes Helicobacter pylori-associated gastric carcinogenesis by directly enhancing CDK4 expression
2020, EBioMedicine
Abnormal expression of the orphan nuclear receptor Nurr1 is a critical factor in the etiology of multiple cancers. However, its potential role in gastric cancer (GC) remains elusive. In this study, we have demonstrated that the expression of Nurr1 was elevated and had an oncogenic function in GC.
Nurr1 expression was analyzed in clinical specimens and the GEO database. Functions of Nurr1 in GC cells were analyzed using Nurr1 knockdown and overexpression. Various cell and molecular biological methods were used to explore the potential mechanisms of Nurr1 upregulation and its role in promoting GC.
Overexpression of Nurr1 was directly related to the poor prognosis of GC patients. What's more, Nurr1 was induced by Helicobacter pylori (H. pylori) via the PI3K/AKT-Sp1 pathway. Sp1 enhanced Nurr1 expression by binding to its promoter to activate the transcription. Upregulated Nurr1 then directly targeted CDK4 by binding to its promoter region to increase its expression, thereby facilitated GC cells proliferation both in vitro and in vivo.
We identified Nurr1 as a driving oncogenic factor in GC. In addition, Nurr1 could be used as a potential therapeutic target for the diagnosis and treatment of H. pylori-associated GC.
This work was supported by the National Natural Science Foundation of China (Nos 81801983, 81871620, 81971901, 81772151 and 81571960), and the Department of Science and Technology of Shandong Province (2018CXGC1208).
The role of transforming growth factor (TGF)-β in modulating the immune response and fibrogenesis in the gut
2014, Cytokine and Growth Factor Reviews
Citation Excerpt :
This is likely to derive from the restoration of endogenous TGF-β activity, as the ex vivo effects of the Smad7 antisense oligonucleotide are decreased by the addition of a TGF-β neutralizing antibody [105]. Elevated levels of Smad7 and impaired TGF-β1 signaling are not specific features of IBD, since the same alterations have been also observed in the gastric mucosa of patients with Helicobacter pylori infection [106]. Treg, while being reduced in peripheral blood of patients with active IBD, are increased in the inflamed intestinal mucosa of IBD patients [107,108].
Transforming growth factor (TGF)-β, a pleiotropic cytokine released by both immune and non-immune cells in the gut, exerts an important tolerogenic action by promoting regulatory T cell differentiation. TGF-β also enhances enterocyte migration and regulates extracellular matrix turnover, thereby playing a crucial role in tissue remodeling in the gut. In this review we describe the mechanisms by which abnormal TGF-β signaling impairs intestinal immune tolerance and tissue repair, thus predisposing to the onset of immune-mediated bowel disorders, such as inflammatory bowel disease and celiac disease. Additionally, we will discuss potential therapeutic strategies aiming at restoring physiologic TGF-β signaling in chronic intestinal diseases.
Smad7 antisense oligonucleotide-based therapy for inflammatory bowel diseases
2013, Digestive and Liver Disease
Citation Excerpt :
In line with this was also the observation that treatment of mucosal explants from CD patients with Smad7 antisense oligonucleotide inhibited Smad7 protein, enhanced Smad3 phosphorylation and decreased inflammatory cytokine production, an effect which was partially blocked by a neutralising TGF-β1 antibody [15]. Up-regulation of Smad7 and diminished expression of phosphorylated Smad3 are not however a specific hallmark of IBD, because similar findings were seen in biopsies taken from Helicobacter pylori-infected patients [20]. By contrast, Smad7 is not up-regulated in the duodenum of patients with active celiac disease [21], suggesting that induction of Smad7 is not an epiphenomenon of the ongoing mucosal inflammation.
The aetiology of both Crohn's disease and ulcerative colitis, the major forms of inflammatory bowel diseases in human beings, remains unknown. However, compelling evidence suggests that the associated pathological process in inflammatory bowel disease is driven by an excessive immune response directed against normal components of the bacterial microflora and marked by defects in counter-regulatory mechanisms, such as those involving transforming growth factor-β1. Indeed, a diminished activity of transforming growth factor-β1, as indicated by a reduced phosphorylation of Smad3, a signalling molecule associated with the activated transforming growth factor-β receptor, is evident in the inflamed gut of inflammatory bowel disease patients and this alteration is due to high Smad7, an intracellular inhibitor of Smad3 phosphorylation. Consistently, silencing of Smad7 with a specific antisense oligonucleotide restores transforming growth factor-β1/Smad3 signalling, thereby leading to inhibition of inflammatory cytokine production and attenuation of experimental colitis in mice. These findings together with the demonstration that Smad7 antisense oligonucleotide is safe and well-tolerated in patients with Crohn's disease indicate that Smad7 antisense oligonucleotide-based pharmaceutical compounds could enter the therapeutic armamentarium of these disorders. In this article we review the available data supporting the pathogenic role of Smad7 in the gut and discuss why Smad7 antisense therapy could help dampen the mucosal inflammation in inflammatory bowel disease.
Smad7 protein induces interferon regulatory factor 1-dependent transcriptional activation of caspase 8 to restore tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis
2013, Journal of Biological Chemistry
Citation Excerpt :
Interestingly, halofuginone has recently been shown to inhibit tumor growth and metastasis through the blocking of angiogenesis and matrix metalloproteinase in various tumors (60, 61). It is well known that IFN-γ induces Smad7 through the Jak1/STAT pathway to block TGF-β signaling (30–32). Because cotreatment of IFN-γ and TRAIL synergistically induced the apoptosis in neuroblastoma cells and Ewing sarcoma, it will be interesting to examine the involvement of Smad7 in this effect based on our study (28, 29, 62).
Smad7 has been known as a negative regulator for the transforming growth factor-β (TGF-β) signaling pathway through feedback regulation. However, Smad7 has been suspected to have other biological roles through the regulation of gene transcription. By screening differentially regulated genes, we found that the caspase 8 gene was highly up-regulated in Smad7-expressing cells. Smad7 was able to activate the caspase 8 promoter through recruitment of the interferon regulatory factor 1 (IRF1) transcription factor to the interferon-stimulated response element (ISRE) site. Interaction of Smad7 on the caspase 8 promoter was confirmed with electrophoretic mobility shift assay and chromatin immunoprecipitation experiment. Interestingly, Smad7 did not directly interact with the ISRE site, but it increased the binding activity of IRF1 with ISRE. These results support that Smad7 recruits IRF1 protein on the caspase 8 promoter and functions as a transcriptional coactivator. To confirm the biological significance of caspase 8 up-regulation, we tested tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-mediated cell death assay in breast cancer cells. Smad7 in apoptosis-resistant MCF7 cells markedly sensitized the cells to TRAIL-induced cell death by restoring the caspase cascade. Furthermore, restoration of caspase 8-mediated apoptosis pathway repressed the tumor growth in the xenograft model. In conclusion, we suggest a novel role for Smad7 as a transcriptional coactivator for caspase 8 through the interaction with IRF1 in regulation of the cell death pathway.
Background: Smad7 may have biological roles other than inhibition of TGF-β signaling.
Results: Smad7 activates caspase 8 expression by recruiting IRF1, thereby inducing TRAIL-mediated apoptosis.
Conclusion: Smad7 functions as a transcriptional coactivator of IRF1 to regulate the expression of target genes.
Significance: Smad7-inducing reagents can be used as anti-cancer drugs for tumors that have defects in caspase 8 expression.

View all citing articles on Scopus

^☆: Supported by the Broad Medical Research Program Foundation.

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Clinical-alimentary tractInduction and regulation of Smad7 in the gastric mucosa of patients with Helicobacter pylori infection☆

Abstract

Section snippets

Patients and sampling

Activated TGF-β1 is produced in the human gastric mucosa

Discussion

Cell

Curr Opin Cell Biol

Cell

The disease spectrum of Helicobacter pylorithe immunopathogenesis of gastroduodenal ulcer and gastric cancer

Annu Rev Microbiol

The role of interleukin-1 polymorphisms in the pathogenesis of gastric cancer

Nature

Role of NF-κB and AP-1 on Helicobacter pylori-induced IL-8 expression in AGS cells

Dig Dis Sci

Mitogen-activated protein kinases and nuclear factor-κB regulate Helicobacter pylori-mediated interleukin-8 release from macrophages

Biochem J

Induction of gastric epithelial cell apoptosis by Helicobacter pylori vacuolating cytotoxin

Cancer Res

T helper 1 effector cells specific for Helicobacter pylori in the gastric antrum of patients with peptic ulcer disease

J Immunol

Helicobacter pylori-induced mucosal inflammation is Th1 mediated and exacerbated in IL-4, but not IFN-γ, gene-deficient mice

J Immunol

The role of T-cell subsets and cytokines in the pathogenesis of Helicobacter pylori gastritis in mice

J Immunol

Regulation of immune responses by TGF-β

Annu Rev Immunol

Transforming growth factor βthe good, the bad, and the ugly

J Exp Med

Clinical-alimentary tract
Induction and regulation of Smad7 in the gastric mucosa of patients with Helicobacter pylori infection☆