scholarly journals Tumor Necrosis Factor-α and Apoptosis Signal-Regulating Kinase 1 Control Reactive Oxygen Species Release, Mitochondrial Autophagy and C-Jun N-Terminal Kinase/P38 Phosphorylation During Necrotizing Enterocolitis

2009 ◽  
Vol 2 (5) ◽  
pp. 297-306 ◽  
Author(s):  
Naira Baregamian ◽  
Jun Song ◽  
C. Eric Bailey ◽  
John Papaconstantinou ◽  
B. Mark Evers ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Mitochondrial Dysfunction ◽  
Tumor Necrosis ◽  
Intestinal Epithelial Cell ◽  
Intestinal Epithelial Cells ◽  
Oxygen Species ◽  
Intestinal Epithelial ◽  
Epithelial Cell Apoptosis ◽  
Necrosis Factor

Background: Oxidative stress and inflammation may contribute to the disruption of the protective gut barrier through various mechanisms; mitochondrial dysfunction resulting from inflammatory and oxidative injury may potentially be a significant source of apoptosis during necrotizing enterocolitis (NEC). Tumor necrosis factor (TNF)α is thought to generate reactive oxygen species (ROS) and activate the apoptosis signal-regulating kinase 1 (ASK1)-c-Jun N-terminal kinase (JNK)/p38 pathway. Hence, the focus of our study was to examine the effects of TNFα/ROs on mitochondrial function, ASK1-JNK/p38 cascade activation in intestinal epithelial cells during NEC.Results: We found (a) abundant tissue TNFα and ASK1 expression throughout all layers of the intestine in neonates with NEC, suggesting that TNFα/ASK1 may be a potential source (indicators) of intestinal injury in neonates with NEC; (b) TNFα-induced rapid and transient activation of JNK/p38 apoptotic signaling in all cell lines suggests that this may be an important molecular characteristic of NEC; (c) TNFα-induced rapid and transient ROs production in RIe-1 cells indicates that mitochondria are the predominant source of ROS, demonstrated by significantly attenuated response in mitochondrial DNA-depleted (RIE-1-ρ°) intestinal epithelial cells; (d) further studies with mitochondria-targeted antioxidant PBN supported our hypothesis that effective mitochondrial ROS trapping is protective against TNFα/ROs-induced intestinal epithelial cell injury; (e) TNFα induces significant mitochondrial dysfunction in intestinal epithelial cells, resulting in increased production of mtROS, drop in mitochondrial membrane potential (MMP) and decreased oxygen consumption; (f) although the significance of mitochondrial autophagy in NEC has not been unequivocally shown, our studies provide a strong preliminary indication that TNFα/ROs-induced mitochondrial autophagy may play a role in NeC, and this process is a late phenomenon.Methods: Paraffin-embedded intestinal sections from neonates with NEC and non-inflammatory condition of the gastrointestinal tract undergoing bowel resections were analyzed for TNFα and ASK1 expression. Rat (RIE-1) and mitochondrial DNA-depleted (RIE-1-ρ°) intestinal epithelial cells were used to determine the effects of TNFα on mitochondrial function.Conclusions: Our findings suggest that TNFα induces significant mitochondrial dysfunction and activation of mitochondrial apoptotic responses, leading to intestinal epithelial cell apoptosis during NeC. Therapies directed against mitochondria/ROS may provide important therapeutic options, as well as ameliorate intestinal epithelial cell apoptosis during NeC.

Tumor necrosis factor regulates intestinal epithelial cell migration by receptor-dependent mechanisms

2003 ◽  
Vol 284 (4) ◽  
pp. C953-C961 ◽  
Author(s):  
Julissa Corredor ◽  
Fang Yan ◽  
Christopher C. Shen ◽  
Wei Tong ◽  
Sutha K. John ◽  
...  
Keyword(s):  
Cell Migration ◽  
Tumor Necrosis Factor ◽  
Epithelial Cell ◽  
Tumor Necrosis ◽  
Intestinal Epithelial Cell ◽  
Wound Closure ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial ◽  
Epithelial Cell Migration ◽  
Necrosis Factor

Altered mucosal integrity and increased cytokine production, including tumor necrosis factor (TNF), are the hallmarks of inflammatory bowel disease (IBD). In this study, we addressed the role of TNF receptors (TNFR) on intestinal epithelial cell migration in an in vitro wound closure model. With mouse TNFR1 or TNFR2 knockout intestinal epithelial cells, gene transfection, and pharmacological inhibitors, we show a concentration-dependent receptor-mediated regulation of intestinal cell migration by TNF. A physiological TNF level (1 ng/ml) enhances migration through TNFR2, whereas a pathological level (100 ng/ml) inhibits wound closure through TNFR1. Increased rate of wound closure by TNFR2 or inhibition by TNFR1 cannot be explained by either increased proliferation or apoptosis, respectively. Furthermore, inhibiting Src tyrosine kinase decreases TNF-induced focal adhesion kinase (FAK) tyrosine phosphorylation and cellular migration. We therefore conclude that TNFR2 activates a novel Src-regulated pathway involving FAK tyrosine phosphorylation that enhances migration of intestinal epithelial cells.

Induction of endothelin-1 synthesis by IL-2 and its modulation of rat intestinal epithelial cell growth

1998 ◽  
Vol 275 (3) ◽  
pp. G556-G563 ◽  
Author(s):  
Takeharu Shigematsu ◽  
Soichiro Miura ◽  
Masahiko Hirokawa ◽  
Ryota Hokari ◽  
Hajime Higuchi ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Growth ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Lines ◽  
Proliferative Response ◽  
Intestinal Epithelial Cell ◽  
Culture Media ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial

Endothelin (ET), a vasoconstrictive peptide, is known to have a variety of biological actions. Although ET is released by vascular endothelial cells, other cell populations also have been reported to synthesize and release ET. In this study, we examined whether ET is synthesized by intestinal epithelial cells and whether it affects induction of epithelial cell proliferation by interleukin-2 (IL-2). Subconfluent monolayers of intestinal epithelial cells (IEC-6 and IEC-18) were maintained in serum-free medium before addition of rat IL-2. Both IEC-6 and IEC-18 cells released ET-1 into the medium under unstimulated conditions, as determined by a sandwich ELISA. IL-2 significantly enhanced ET-1 release in a time-dependent manner. ET-3 was not detectable in the culture media of either cell line. Expression of ET-1 and ET-3 mRNA in epithelial cells was assessed by competitive PCR. Both cell lines were shown to express ET-1 mRNA, but no ET-3 mRNA was detected. IL-2 treatment enhanced ET-1 mRNA expression by both IEC-6 and IEC-18 cells. Both cell lines also expressed mRNA for ETA and ETB receptor subtypes. When cell proliferation was assessed, exogenous ET-1 induced a slight proliferative response in both types of cells that was consistent and significant at low ET-1 concentrations; cell growth was inhibited at a higher concentration (10−7M). IL-2 produced a significant proliferative response in both cell lines. However, the addition of ET-1 (10−7 M) to culture media attenuated the IL-2-induced increase in cell proliferation. ETA-receptor antagonists significantly enhanced cellular proliferation, suggesting involvement of the ETA receptor in modulation of IL-2-induced intestinal epithelial cell growth.

scholarly journals Regulation of NF-κB responses by epigenetic suppression of IκBα expression in HCT116 intestinal epithelial cells

2010 ◽  
Vol 299 (1) ◽  
pp. G96-G105 ◽  
Author(s):  
Angela O'Gorman ◽  
Amy Colleran ◽  
Aideen Ryan ◽  
Jelena Mann ◽  
Laurence John Egan
Keyword(s):  
Epithelial Cells ◽  
Tumor Necrosis ◽  
Tumor Necrosis Factor Α ◽  
Intestinal Epithelial Cells ◽  
Gene Promoter ◽  
Intestinal Epithelial ◽  
Epigenetic Factors ◽  
Factor Α ◽  
Necrosis Factor ◽  
Hct116 Cells

Intestinal epithelial cells play critical roles in regulating mucosal immunity. Since epigenetic factors such as DNA methylation and histone modifications are implicated in aging, carcinogenesis, and immunity, we set out to assess any role for epigenetic factors in the regulation of intestinal epithelial cell immune responses. Experiments were conducted using the HCT116 cell line, and a subclone was genetically engineered to lack DNA methyltransferases (DNMT). The induction of the chemokine interleukin-8 and the antiapoptotic protein cFLIP by tumor necrosis factor-α were markedly less in HCT116 cells lacking DNMT than in parental cells. These effects were accompanied by lower monocyte chemotaxis and higher caspase signaling in HCT116 cells lacking DNMT than parental cells. Tumor necrosis factor-α-induced NF-κB activation was blocked and IκBα expression was higher in HCT116 cells lacking DNMT than in parental cells. A CpG island in the IκBα gene promoter region was found to contain variable levels of methylation in parental HCT116 cells. Chromatin immunoprecipitation analysis of histone proteins bound to the IκBα gene promoter revealed that higher levels of IκBα expression in HCT116 cells lacking DNMT compared with parental cells were accompanied by more chromatin marks permissive to gene transcription. These findings show that epigenetic factors influence the NF-κB system in intestinal epithelial cells, resulting in a previously unrecognized mechanism of innate immune regulation.

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