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.

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Epidermal growth factor receptor inhibition downregulates Helicobacter pylori-induced epithelial inflammatory responses, DNA damage and gastric carcinogenesis

Gut ◽

10.1136/gutjnl-2016-312888 ◽

2017 ◽

Vol 67 (7) ◽

pp. 1247-1260 ◽

Cited By ~ 33

Author(s):

Johanna C Sierra ◽

Mohammad Asim ◽

Thomas G Verriere ◽

M Blanca Piazuelo ◽

Giovanni Suarez ◽

...

Keyword(s):

Dna Damage ◽

Epidermal Growth Factor Receptor ◽

Epithelial Cells ◽

Growth Factor Receptor ◽

Inflammatory Cells ◽

Gastric Carcinogenesis ◽

Gastric Epithelial Cells ◽

Egfr Activation ◽

Epidermal Growth ◽

H Pylori

ObjectiveGastric cancer is the third leading cause of cancer death worldwide and infection by Helicobacter pylori is the strongest risk factor. We have reported increased epidermal growth factor receptor (EGFR) phosphorylation in the H. pylori-induced human carcinogenesis cascade, and association with DNA damage. Our goal was to determine the role of EGFR activation in gastric carcinogenesis.DesignWe evaluated gefitinib, a specific EGFR inhibitor, in chemoprevention of H. pylori-induced gastric inflammation and cancer development. Mice with genetically targeted epithelial cell-specific deletion of Egfr (EfgrΔepi mice) were also used.ResultsIn C57BL/6 mice, gefitinib decreased Cxcl1 and Cxcl2 expression by gastric epithelial cells, myeloperoxidase-positive inflammatory cells in the mucosa and epithelial DNA damage induced by H. pylori infection. Similar reductions in chemokines, inflammatory cells and DNA damage occurred in infected EgfrΔepi versus Egfrfl/fl control mice. In H. pylori-infected transgenic insulin-gastrin (INS-GAS) mice and gerbils, gefitinib treatment markedly reduced dysplasia and carcinoma. Gefitinib blocked H. pylori-induced activation of mitogen-activated protein kinase 1/3 (MAPK1/3) and activator protein 1 in gastric epithelial cells, resulting in inhibition of chemokine synthesis. MAPK1/3 phosphorylation and JUN activation was reduced in gastric tissues from infected wild-type and INS-GAS mice treated with gefitinib and in primary epithelial cells from EfgrΔepi versus Egfrfl/fl mice. Epithelial EGFR activation persisted in humans and mice after H. pylori eradication, and gefitinib reduced gastric carcinoma in INS-GAS mice treated with antibiotics.ConclusionsThese findings suggest that epithelial EGFR inhibition represents a potential strategy to prevent development of gastric carcinoma in H. pylori-infected individuals.

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Evidence for function of Ia molecules on gut epithelial cells in man.

Journal of Experimental Medicine ◽

10.1084/jem.166.5.1471 ◽

1987 ◽

Vol 166 (5) ◽

pp. 1471-1483 ◽

Cited By ~ 389

Author(s):

L Mayer ◽

R Shlien

Keyword(s):

Immune Response ◽

T Cells ◽

T Cell ◽

Epithelial Cells ◽

Immune Responses ◽

Mucosal Immunity ◽

Suppressor Cells ◽

Soluble Antigen ◽

B Cell Differentiation ◽

Accessory Cells

Using freshly isolated Ia+ gut epithelial cells we have been able to demonstrate that these cells can function as accessory cells in an immune response. The cells can act as stimulators in both autologous and allogeneic MLRs. More importantly, these cells are capable of taking up the soluble antigen, tetanus toxoid, processing it, and presenting it to tetanus-primed T cells. These functions appear to relate to the presence of surface Ia in that a hetero-anti-Ia antibody can block these effects. Noteworthy is the finding that the subpopulation of T cells stimulated when epithelial cells are used as accessory cells is the T8+, 9.3-T cell. These cells function as potent antigen-nonspecific suppressor cells in both MLR, T cell antigen responses, and induction of B cell differentiation by PWM. These findings have significant implications in local gut immune responses and may help explain several poorly characterized phenomena of mucosal immunity.

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Coordinated oncogenic transformation and inhibition of host immune responses by the PAX3-FKHR fusion oncoprotein

Journal of Experimental Medicine ◽

10.1084/jem.20050730 ◽

2005 ◽

Vol 202 (10) ◽

pp. 1399-1410 ◽

Cited By ~ 40

Author(s):

Stephen Nabarro ◽

Nourredine Himoudi ◽

Antigoni Papanastasiou ◽

Kimberly Gilmour ◽

Sian Gibson ◽

...

Keyword(s):

Transcription Factor ◽

Immune Responses ◽

Fusion Protein ◽

Metastatic Cancer ◽

Specific Interaction ◽

Inflammatory Cells ◽

Janus Kinase ◽

Host Immune Responses ◽

Expression Of Genes ◽

Immune Detection

Tumors have evolved elaborate mechanisms for evading immune detection, such as production of immunoinhibitory cytokines and down-regulation of major histocompatibility complex (MHC) expression. We have studied PAX3-FKHR as an example of an oncogenic fusion protein associated with an aggressive metastatic cancer. We show that PAX3-FKHR alters expression of genes that are normally regulated by Janus kinase/signal transducer and activator of transcription (STAT) signaling pathways. This occurs as a result of a specific interaction between PAX3-FKHR and the STAT3 transcription factor, which results in a dramatic reduction in tumor MHC expression, and an alteration in local cytokine concentrations to inhibit surrounding inflammatory cells and immune detection. Collectively, these data show that an oncogenic transcription factor can promote tumor growth and tissue invasion while inhibiting local inflammatory and immune responses. This is the first time that an immunomodulatory role has been described for an oncogenic fusion protein.

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Review: Defensins and cathelicidins in lung immunity

Innate Immunity ◽

10.1177/1753425910365734 ◽

2010 ◽

Vol 16 (3) ◽

pp. 151-159 ◽

Cited By ~ 105

Author(s):

Tesfaldet Tecle ◽

Shweta Tripathi ◽

Kevan L. Hartshorn

Keyword(s):

Epithelial Cells ◽

Immune Responses ◽

Biological Activities ◽

Large Family ◽

Inflammatory Cells ◽

Respiratory Epithelial Cells ◽

Spectrum Activity ◽

Respiratory Epithelial ◽

Lung Immunity

Defensins were first identified in 1985 and are now recognized as part of a large family of antimicrobial peptides, divided into three categories: α-, β-, and θ-defensins. These defensin classes differ in structure, sites of expression and biological activities. Human α-defensins include peptides that are expressed primarily in neutrophils, whereas human β-defensins are widely expressed in epithelial cells, including those lining the respiratory tract. Defensins were first studied for their broad spectrum activity against bacteria, fungi and viruses; however, it is now clear that they also recruit inflammatory cells and promote innate and adaptive immune responses. Recent evidence shows that defensins have anti-inflammatory effects as well. Hence, defensins can participate in all phases of an immune response in the lung, including initial killing of pathogens and mounting — and resolution —- of an immune or inflammatory response. The cathelicidin, LL-37, is an antimicrobial peptide produced by neutrophils and respiratory epithelial cells that has similar roles in lung immunity as the defensins. A major challenge for the coming years will be to sort out the relative contributions of defensins and LL-37 to overall immune responses in the lung and to determine which of their many in vitro activities are most important for lung immunity.

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Helicobacter pylori Induces Apoptosis of Macrophages in Association with Alterations in the Mitochondrial Pathway

Infection and Immunity ◽

10.1128/iai.72.5.2889-2898.2004 ◽

2004 ◽

Vol 72 (5) ◽

pp. 2889-2898 ◽

Cited By ~ 58

Author(s):

Rena J. Menaker ◽

Peter J. M. Ceponis ◽

Nicola L. Jones

Keyword(s):

Helicobacter Pylori ◽

Immune Responses ◽

Annexin V ◽

Mitochondrial Pathway ◽

Time Dependent ◽

Raw 264.7 Cells ◽

Cell Protein ◽

Host Immune Responses ◽

H Pylori

ABSTRACT Helicobacter pylori is a gastric bacterial pathogen that evades host immune responses in vivo and is associated with the development of gastritis, peptic ulcer disease, and gastric cancers. Induction of macrophage apoptosis is a method employed by multiple pathogens to escape host immune responses. Therefore, we hypothesized that H. pylori induces apoptosis of infected macrophages. RAW 264.7 cells were infected with H. pylori strain 60190, and apoptosis was assessed. Transmission electron microscopy and fluorescence microscopy showed that infected macrophages displayed morphological features characteristic of apoptosis. Quantification by acridine orange-ethidium bromide fluorescent-dye staining showed that apoptosis was dose and time dependent, and apoptosis was further confirmed by increased binding of annexin V-fluorescein isothiocyanate (FITC) to externalized phosphatidylserine of infected but not of control macrophages. Macrophages infected with isogenic mutants of H. pylori strain 60190 deficient in either cagA or vacA induced significantly less apoptosis than the parental strain, as assessed by increased binding of annexin V-FITC. Western blot analysis of whole-cell protein lysates revealed that infection with strain 60190 induced a time-dependent increase in cleavage of procaspase 8 and disappearance of full-length Bid compared with uninfected cells. Furthermore, pharmacological inhibition of caspase 8 caused a decrease in levels of apoptosis. Finally, infection caused a time-dependent increase in mitochondrial-membrane permeability and release of cytochrome c into the cytosol. These results suggest that H. pylori induces apoptosis of macrophages in association with alterations in the mitochondrial pathway. Elimination of this key immunomodulatory cell may represent a mechanism employed by the bacterium to evade host immune responses.

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Unconventional secretion of unglycosylated ORF8 is critical for the cytokine storm during SARS-CoV-2 infection

10.1101/2021.12.03.471057 ◽

2021 ◽

Author(s):

Xiaoyuan Lin ◽

Beibei Fu ◽

Yan Xiong ◽

Na Xing ◽

Weiwei Xue ◽

...

Keyword(s):

Epithelial Cells ◽

Immune Responses ◽

Secretory Protein ◽

Alveolar Epithelial Cells ◽

Reading Frame ◽

Functional Roles ◽

Alveolar Epithelial ◽

Host Immune Responses ◽

Unconventional Secretion ◽

Delayed Mortality

AbstractCoronavirus disease 2019 is a respiratory infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Evidence on the pathogenesis of SARS-CoV-2 is accumulating rapidly. In addition to structural proteins such as Spike and Envelope, the functional roles of non-structural and accessory proteins in regulating viral life cycle and host immune responses remain to be understood. Here, we show that open reading frame 8 (ORF8) acts as messenger for inter-cellular communication between alveolar epithelial cells and macrophages during SARS-CoV-2 infection. Mechanistically, ORF8 is a secretory protein that can be secreted by infected epithelial cells via both conventional and unconventional secretory pathways. The unconventionally secreted ORF8 recognizes the IL17RA receptor of macrophages and induces cytokine release. However, conventionally secreted ORF8 cannot bind to IL17RA due to N-linked glycosylation. Furthermore, we found that Yip1 interacting factor homolog B (YIF1B) is a channel protein that translocates unglycosylated ORF8 into vesicles for unconventional secretion. Blocking the unconventional secretion of ORF8 via a YIF1B knockout in hACE2 mice attenuates inflammation and yields delayed mortality following SARS-CoV-2 challenge.

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Nod1 acts as an intracellular receptor to stimulate chemokine production and neutrophil recruitment in vivo

Journal of Experimental Medicine ◽

10.1084/jem.20051229 ◽

2006 ◽

Vol 203 (1) ◽

pp. 203-213 ◽

Cited By ~ 147

Author(s):

Junya Masumoto ◽

Kangkang Yang ◽

Sooryanarayana Varambally ◽

Mizuho Hasegawa ◽

Scott A. Tomlins ◽

...

Keyword(s):

Epithelial Cells ◽

Immune Responses ◽

Inflammatory Cells ◽

Interferon Γ ◽

Innate Immune ◽

Host Recognition ◽

Interleukin 12 ◽

Primary Role ◽

Chemokine Production

Nod1 is a member of family of intracellular proteins that mediate host recognition of bacterial peptidoglycan. To characterize immune responses mediated by Nod1, synthetic ligand compounds possessing enhanced ability to stimulate Nod1 were developed to study the function of Nod1. Stimulation of epithelial cells with Nod1 stimulatory molecules induced chemokines and other proinflammatory molecules that are important for innate immune responses and recruitment of acute inflammatory cells. Administration of Nod1 ligands into mice induced chemokines and recruitment of acute inflammatory cells, an activity that was abolished in Nod1-null mice. Microarray analysis revealed that Nod1 stimulation induces a restricted number of genes in intestinal epithelial cells compared with that induced by tumor necrosis factor (TNF) α. Nod1 stimulation did not induce TNFα, interleukin 12, and interferon γ, suggesting that the primary role of Nod1 is to induce the recruitment of immune cells. These results indicate that Nod1 functions as a pathogen recognition molecule to induce expression of molecules involved in the early stages of the innate immune response.

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Helicobacter pylori Activates Myosin Light-Chain Kinase To Disrupt Claudin-4 and Claudin-5 and Increase Epithelial Permeability

Infection and Immunity ◽

10.1128/iai.73.12.7844-7852.2005 ◽

2005 ◽

Vol 73 (12) ◽

pp. 7844-7852 ◽

Cited By ~ 85

Author(s):

Jason P. Fedwick ◽

Tamia K. Lapointe ◽

Jonathan B. Meddings ◽

Philip M. Sherman ◽

Andre G. Buret

Keyword(s):

Helicobacter Pylori ◽

Epithelial Cells ◽

Light Chain ◽

Myosin Light Chain Kinase ◽

Myosin Light Chain ◽

Inflammatory Cells ◽

Epithelial Permeability ◽

Ags Cells ◽

Junctional Proteins ◽

H Pylori

ABSTRACT Helicobacter pylori is a spiral, gram-negative bacterium that specifically and persistently infects the human stomach. In some individuals, H. pylori-induced chronic gastritis may progress to gastroduodenal ulcers and gastric cancer. Currently, the host-microbe interactions that determine the clinical outcome of infection are not well defined. H. pylori strains capable of disrupting the gastric epithelial barrier may increase the likelihood of developing serious disease. In this study, H. pylori strain SS1 increased gastric, but not small intestinal, permeability in C57BL/6 mice. H. pylori strain SS1 was able to directly increase paracellular permeability, in the absence of host inflammatory cells, by disrupting the tight-junctional proteins occludin, claudin-4, and claudin-5 in confluent nontransformed epithelial cells. H. pylori SS1 also reduced claudin-4 protein levels in human gastric AGS cells. The ability of H. pylori SS1 to increase permeability appeared to be independent of the well-characterized virulence factors vacuolating cytotoxin and CagA protein. H. pylori activated myosin light-chain kinase in epithelial cells to phosphorylate myosin light chain and increase permeability by disrupting claudin-4 and claudin-5. The bacterial factor responsible for increasing epithelial permeability was heat sensitive, membrane bound, and required apical contact with monolayers. In conclusion, disruptions of the tight junctions observed in this study implicate host cell signaling pathways, including the phosphorylation of myosin light chain and the regulation of tight-junctional proteins claudin-4 and claudin-5, in the pathogenesis of H. pylori infection.

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