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

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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.


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Disruption of lipid rafts reduces H. pylori-induced IL-8 production. AGS cells were transfected with an IL-8 luciferase reporter in the absence or presence of 5 mM MβCD prior to infection with H. pylori (MOI = 100) for 6 h. (A) Cell lysates were subjected to luciferase activity assay to assess IL-8 promoter activity. (B) IL-8 secretions in the cell culture supernatants were assessed by ELISA. Statistical significance was evaluated by Student’s t-test (*P < 0.05).
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Figure 8: Disruption of lipid rafts reduces H. pylori-induced IL-8 production. AGS cells were transfected with an IL-8 luciferase reporter in the absence or presence of 5 mM MβCD prior to infection with H. pylori (MOI = 100) for 6 h. (A) Cell lysates were subjected to luciferase activity assay to assess IL-8 promoter activity. (B) IL-8 secretions in the cell culture supernatants were assessed by ELISA. Statistical significance was evaluated by Student’s t-test (*P < 0.05).

Mentions: We next examined whether cholesterol-rich microdomains were essential for H. pylori-induced IL-8 production. AGS cells were untreated or pretreated with MβCD and then incubated with H. pylori for 6 h. Results showed that MβCD treatment significantly suppressed IL-8 promoter activity in H. pylori-infected cells (Figure 8A). Similarly, H. pylori-induced IL-8 production in cells was markedly reduced when cholesterol-rich microdomains were disrupted by MβCD (Figure 8B). Taken together, results from this study demonstrate that depletion of cholesterol inhibits the mobilization of RAGE into cholesterol-rich microdomains, thereby mitigating H. pylori-induced inflammation.


Helicobacter pylori Activates HMGB1 Expression and Recruits RAGE into Lipid Rafts to Promote Inflammation in Gastric Epithelial Cells
Disruption of lipid rafts reduces H. pylori-induced IL-8 production. AGS cells were transfected with an IL-8 luciferase reporter in the absence or presence of 5 mM MβCD prior to infection with H. pylori (MOI = 100) for 6 h. (A) Cell lysates were subjected to luciferase activity assay to assess IL-8 promoter activity. (B) IL-8 secretions in the cell culture supernatants were assessed by ELISA. Statistical significance was evaluated by Student’s t-test (*P < 0.05).
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Related In: Results  -  Collection

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Figure 8: Disruption of lipid rafts reduces H. pylori-induced IL-8 production. AGS cells were transfected with an IL-8 luciferase reporter in the absence or presence of 5 mM MβCD prior to infection with H. pylori (MOI = 100) for 6 h. (A) Cell lysates were subjected to luciferase activity assay to assess IL-8 promoter activity. (B) IL-8 secretions in the cell culture supernatants were assessed by ELISA. Statistical significance was evaluated by Student’s t-test (*P < 0.05).
Mentions: We next examined whether cholesterol-rich microdomains were essential for H. pylori-induced IL-8 production. AGS cells were untreated or pretreated with MβCD and then incubated with H. pylori for 6 h. Results showed that MβCD treatment significantly suppressed IL-8 promoter activity in H. pylori-infected cells (Figure 8A). Similarly, H. pylori-induced IL-8 production in cells was markedly reduced when cholesterol-rich microdomains were disrupted by MβCD (Figure 8B). Taken together, results from this study demonstrate that depletion of cholesterol inhibits the mobilization of RAGE into cholesterol-rich microdomains, thereby mitigating H. pylori-induced inflammation.

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.


Related in: MedlinePlus