Aged HCT-8 Cell Monolayers Support Cryptosporidium parvum Infection

The Journal of Immunology

et al. 2013

In response to excessive nucleotide-binding oligomerization domain–containing protein 2 (Nod2) stimulation caused by mucosal bacterial components, gut epithelia need to activate regulatory machinery to maintain epithelial homeostasis. Activating transcription factor 3 (ATF3) is a representative regulator in the negative feedback loop that modulates TLR-associated inflammatory responses. In the current study, the regulatory effects of ribosomal stress-induced ATF3 on Nod2-stimulated proinflammatory signals were assessed. Ribosomal inactivation caused persistent ATF3 expression that in turn suppressed proinflammatory chemokine production facilitated by Nod2. Decreased chemokine production was due to attenuation of Nod2-activated NF-κB and early growth response protein 1 (EGR-1) signals by ATF3. However, the underlying molecular mechanisms involve two convergent regulatory pathways. Although ATF3 induced by ribosomal inactivation regulated Nod2-induced EGR-1 expression epigenetically through the recruitment of histone deacetylase 1, NF-κB regulation was associated with posttranscriptional regulation by ATF3 rather than epigenetic modification. ATF3 induced by ribosomal inactivation led to the destabilization of p65 mRNA caused by nuclear entrapment of transcript-stabilizing human Ag R protein via direct interaction with ATF3. These findings demonstrate that ribosomal stress-induced ATF3 is a critical regulator in the convergent pathways between EGR-1 and NF-κB, which contributes to the suppression of Nod2-activated proinflammatory gene expression.

Section: Nod2-induced Proinflammatory Chemokines Are Suppressed By Insupporting

confidence: 73%

Novel Regulatory Action of Ribosomal Inactivation on Epithelial Nod2-Linked Proinflammatory Signals in Two Convergent ATF3-Associated Pathways

Park

Hun

The Journal of Immunology

et al. 2013

“…1B) intestines. The effects of ribosomal insult on BAFF expression was also assessed in cultured intestinal epithelial HCT-8 cells, which are frequently used as a human epithelial cell model of microbial infection and inflammatory diseases (46)(47)(48). Moreover, the source of HCT-8 cells, the ileocecum of the human small intestine, is one of the organs most susceptible to pathogenesis associated with ribosomal insult (49,50).…”

Section: Ribosomal Insults Suppress Baff Gene Expression In Intestinamentioning

confidence: 99%

SOCS3 Regulates BAFF in Human Enterocytes under Ribosomal Stress

Hun

The Journal of Immunology

Kim

et al. 2013

Although the activation of B cells in the gastrointestinal tract is of great importance in the context of immunity to pathogens and mucosal inflammatory diseases, little is known about the mechanisms responsible for the local activation of B cells in the subepithelial area of the intestine. Epithelium-derived BAFF is the major modulator of B cell development and Ig class switching. The present study was performed to address the molecular mechanism of BAFF expression in gut epithelial cells in the presence of proinflammatory stimuli. Inflammation-induced BAFF expression in mucosal epithelial cells might be responsible for diverse mucosa-associated diseases linked to intestinal inflammation and autoimmunity. Although BAFF was marginally expressed in unstimulated epithelial cells, BAFF mRNA was significantly upregulated by proinflammatory IFN-γ. Furthermore, IFN-γ triggered JAK/STAT1 signals via the cytokine receptor, which contributed to epithelial BAFF upregulation. In terms of signaling intervention, ribosomal insult attenuated IFN-γ–activated JAK/STAT signal transduction and subsequent BAFF induction in gut epithelial cells. Ribosomal insults led to the superinduction of SOCS3 by enhancing its mRNA stability via HuR RNA-binding protein. Upregulated SOCS3 then contributed to the blocking of the JAK/STAT-linked signal, which mediated BAFF suppression by ribosomal stress. All of these findings show that ribosomal stress–induced SOCS3 plays a novel regulatory role in epithelial BAFF production, suggesting that epithelial ribosomal dysfunction in association with SOCS3 may be a promising therapeutic point in BAFF-associated human mucosal diseases.

“…HCT-8 human intestinal epithelial cells were treated with the bacterial cell culture medium, and the activation of the human EGF receptor was analyzed. HCT-8 cells are a frequently used human epithelial cell culture model for microbial infection, ulceration, and inflammatory diseases (2,40,41) and were used in the assessment of intestinal wound healing. Following the addition of each bacterial culture supernatant, the tyrosine phosphorylation of EGFR was observed with a peak at 10 to 20 min after exposure.…”

Section: Expression Of Human Egf In E Coli Nissle 1917mentioning

confidence: 99%

Enhanced Wound Healing by Recombinant Escherichia coli Nissle 1917 via Human Epidermal Growth Factor Receptor in Human Intestinal Epithelial Cells: Therapeutic Implication Using Recombinant Probiotics

Ahn²,

Park

et al. 2012

Infect Immun

The gastrointestinal mucosa has a remarkable ability to repair damage with the support of epidermal growth factor (EGF), which stimulates epithelial migration and proliferative reepithelialization. For the treatment of mucosal injuries, it is important to develop efficient methods for the localized delivery of mucoactive biotherapeutics. The basic idea in the present study came from the assumption that an intestinal probiotic vehicle can carry and deliver key recombinant medicinal proteins to the injured epithelial target in patients with intestinal ulcerative diseases, including inflammatory bowel disease. The study was focused on the use of the safe probiotic E. coli Nissle 1917, which was constructed to secrete human EGF in conjunction with the lipase ABC transporter recognition domain (LARD). Using the in vitro physically wounded monolayer model, ABC transporter-mediated EGF secretion by probiotic E. coli Nissle 1917 was demonstrated to enhance the wound-healing migration of human enterocytes. Moreover, the epithelial wound closure was dependent on EGF receptor-linked activation, which exclusively involved the subsequent signaling pathway of the mitogen-activated protein kinase kinase (MEK) extracellular-related kinases 1 and 2 (ERK1/2). In particular, the migrating frontier of the wounded edge displayed the strongest EGF receptor-linked signaling activation in the presence of the recombinant probiotic. The present study provides a basis for the clinical application of human recombinant biotherapeutics via an efficient, safe probiotic vehicle.