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Helicobacter pylori Activates HMGB1 Expression and Recruits RAGE into Lipid Rafts to Promote Inflammation in Gastric Epithelial Cells

View Article: PubMed Central - PubMed

ABSTRACT

Helicobacter pylori infection is associated with several gastrointestinal disorders in the human population worldwide. High-mobility group box 1 (HMGB1), a ubiquitous nuclear protein, mediates various inflammation functions. The interaction between HMGB1 and receptor for advanced glycation end-products (RAGE) triggers nuclear factor (NF)-κB expression, which in turn stimulates the release of proinflammatory cytokines, such as interleukin (IL)-8, and enhances the inflammatory response. However, how H. pylori activates HMGB1 expression and mobilizes RAGE into cholesterol-rich microdomains in gastric epithelial cells to promote inflammation has not been explored. In this study, we found that HMGB1 and RAGE expression increased significantly in H. pylori-infected cells compared with -uninfected cells. Blocking HMGB1 by neutralizing antibody abrogated H. pylori-elicited RAGE, suggesting that RAGE expression follows HMGB1 production, and silenced RAGE-attenuated H. pylori-mediated NF-κB activation and IL-8 production. Furthermore, significantly more RAGE was present in detergent-resistant membranes extracted from H. pylori-infected cells than in those from -uninfected cells, indicating that H. pylori exploited cholesterol to induce the HMGB1 signaling pathway. These results indicate that HMGB1 plays a crucial role in H. pylori-induced inflammation in gastric epithelial cells, which may be valuable in developing treatments for H. pylori-associated diseases.

No MeSH data available.


HMGB1 is crucial for RAGE expression in H. pylori-infected cells. AGS cells were untreated or pretreated with 1 μg/ml of isotype IgG or anti-HMGB1 at 37°C for 30 min and then infected with H. pylori at an MOI of 100 for 6 h. RAGE mRNA and protein expression levels were measured by (A) quantitative real-time PCR and (B) Western blot analysis, respectively. Results are expressed as means ± SDs. *P < 0.05.
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Figure 4: HMGB1 is crucial for RAGE expression in H. pylori-infected cells. AGS cells were untreated or pretreated with 1 μg/ml of isotype IgG or anti-HMGB1 at 37°C for 30 min and then infected with H. pylori at an MOI of 100 for 6 h. RAGE mRNA and protein expression levels were measured by (A) quantitative real-time PCR and (B) Western blot analysis, respectively. Results are expressed as means ± SDs. *P < 0.05.

Mentions: Confocal microscopy was used to observe HMGB1 expression in AGS cells. As shown in Figure 3, without H. pylori, the image showed faint HMGB1 staining in cell nuclei. In contrast, the distribution of fluorescence clearly showed that HMGB1 localized in both the nucleus and the cytoplasm of cells upon H. pylori infection. We then analyzed RAGE expression in response to H. pylori-induced HMGB1. AGS cells were mock-treated or -pretreated with isotype IgG or neutralizing antibody against HMGB1 (α-HMGB1) for 30 min and then incubated with H. pylori for 6 h. As shown in Figure 4, blocking of HMGB1 by α-HMGB1 significantly reduced H. pylori-induced RAGE mRNA and protein levels, whereas this mock-treated cells or cells treated with isotype IgG showed no such effect. These results indicate that H. pylori infection induces HMGB1 expression, which in turn elicits the production of RAGE in gastric epithelial cells.


Helicobacter pylori Activates HMGB1 Expression and Recruits RAGE into Lipid Rafts to Promote Inflammation in Gastric Epithelial Cells
HMGB1 is crucial for RAGE expression in H. pylori-infected cells. AGS cells were untreated or pretreated with 1 μg/ml of isotype IgG or anti-HMGB1 at 37°C for 30 min and then infected with H. pylori at an MOI of 100 for 6 h. RAGE mRNA and protein expression levels were measured by (A) quantitative real-time PCR and (B) Western blot analysis, respectively. Results are expressed as means ± SDs. *P < 0.05.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016528&req=5

Figure 4: HMGB1 is crucial for RAGE expression in H. pylori-infected cells. AGS cells were untreated or pretreated with 1 μg/ml of isotype IgG or anti-HMGB1 at 37°C for 30 min and then infected with H. pylori at an MOI of 100 for 6 h. RAGE mRNA and protein expression levels were measured by (A) quantitative real-time PCR and (B) Western blot analysis, respectively. Results are expressed as means ± SDs. *P < 0.05.
Mentions: Confocal microscopy was used to observe HMGB1 expression in AGS cells. As shown in Figure 3, without H. pylori, the image showed faint HMGB1 staining in cell nuclei. In contrast, the distribution of fluorescence clearly showed that HMGB1 localized in both the nucleus and the cytoplasm of cells upon H. pylori infection. We then analyzed RAGE expression in response to H. pylori-induced HMGB1. AGS cells were mock-treated or -pretreated with isotype IgG or neutralizing antibody against HMGB1 (α-HMGB1) for 30 min and then incubated with H. pylori for 6 h. As shown in Figure 4, blocking of HMGB1 by α-HMGB1 significantly reduced H. pylori-induced RAGE mRNA and protein levels, whereas this mock-treated cells or cells treated with isotype IgG showed no such effect. These results indicate that H. pylori infection induces HMGB1 expression, which in turn elicits the production of RAGE in gastric epithelial cells.

View Article: PubMed Central - PubMed

ABSTRACT

Helicobacter pylori infection is associated with several gastrointestinal disorders in the human population worldwide. High-mobility group box 1 (HMGB1), a ubiquitous nuclear protein, mediates various inflammation functions. The interaction between HMGB1 and receptor for advanced glycation end-products (RAGE) triggers nuclear factor (NF)-&kappa;B expression, which in turn stimulates the release of proinflammatory cytokines, such as interleukin (IL)-8, and enhances the inflammatory response. However, how H. pylori activates HMGB1 expression and mobilizes RAGE into cholesterol-rich microdomains in gastric epithelial cells to promote inflammation has not been explored. In this study, we found that HMGB1 and RAGE expression increased significantly in H. pylori-infected cells compared with -uninfected cells. Blocking HMGB1 by neutralizing antibody abrogated H. pylori-elicited RAGE, suggesting that RAGE expression follows HMGB1 production, and silenced RAGE-attenuated H. pylori-mediated NF-&kappa;B activation and IL-8 production. Furthermore, significantly more RAGE was present in detergent-resistant membranes extracted from H. pylori-infected cells than in those from -uninfected cells, indicating that H. pylori exploited cholesterol to induce the HMGB1 signaling pathway. These results indicate that HMGB1 plays a crucial role in H. pylori-induced inflammation in gastric epithelial cells, which may be valuable in developing treatments for H. pylori-associated diseases.

No MeSH data available.