Helicobacter pylori disrupts gastric mucosal homeostasis by stimulating macrophages to secrete CCL3
Yan-Fei Wei1, Xue Li1, Meng-Ran Zhao1,2
1Department of Gastroenterology, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, China.
Background:
Helicobacter pylori (H. pylori) is the predominant etiological agent of gastritis and disrupts the integrity of the gastric mucosal barrier through various pathogenic mechanisms. After H. pylori invades the gastric mucosa, it interacts with immune cells in the lamina propria. Macrophages are central players in the inflammatory response, and H. pylori stimulates them to secrete a variety of inflammatory factors, leading to the chronic damage of the gastric mucosa. Therefore, the study aims to explore the mechanism of gastric mucosal injury caused by inflammatory factors secreted by macrophages, which may provide a new mechanism for the development of H. pylori-related gastritis.
Methods:
The expression and secretion of CCL3 from H. pylori infected macrophages were detected by RT-qPCR, Western blot and ELISA. The effect of H. pylori-infected macrophage culture medium and CCL3 on gastric epithelial cells tight junctions were analyzed by Western blot, immunofluorescence and transepithelial electrical resistance. EdU and apoptotic flow cytometry assays were used to detect cell proliferation and apoptosis levels. Dual-luciferase reporter assays and chromatin immunoprecipitation assays were used to study CCL3 transcription factors. Finally, gastric mucosal tissue inflammation and CCL3 expression were analyzed by hematoxylin and eosin staining and immunohistochemistry.
Results:
After H. pylori infection, CCL3 expressed and secreted from macrophages were increased. H. pylori-infected macrophage culture medium and CCL3 disrupted gastric epithelial cells tight junctions, while CCL3 neutralizing antibody and receptor inhibitor of CCL3 improved the disruption of tight junctions between cells. In addition, H. pylori-infected macrophage culture medium and CCL3 recombinant proteins stimulated P38 phosphorylation, and P38 phosphorylation inhibitor improved the disruption of tight junctions between cells. Besides, it was identified that STAT1 was a transcription factor of CCL3 and H. pylori stimulated macrophage to secret CCL3 through the JAK1-STAT1 pathway. Finally, after mice were injected with murine CCL3 recombinant protein, the gastric mucosal injury and inflammation were aggravated, and the phosphorylation level of P38 was increased.
Conclusions:
In summary, our findings demonstrate that H. pylori infection stimulates macrophages to secrete CCL3 via the JAK1-STAT1 pathway. Subsequently, CCL3 damages gastric epithelial tight junctions through the phosphorylation of P38. This may be a novel mechanism of gastric mucosal injury in H. pylori-associated gastritis.
Insights
Helicobacter pylori infection triggers macrophages to release CCL3, a key factor in damaging gastric epithelial tight junctions via P38 phosphorylation, offering a new insight into H. pylori gastritis.
Area of Science:
- Gastroenterology
- Immunology
- Cell Biology
Background:
- Helicobacter pylori (H. pylori) is a primary cause of gastritis, damaging the gastric lining.
- H. pylori interacts with macrophages, leading to inflammatory factor secretion and chronic mucosal damage.
Purpose of the Study:
- To investigate the mechanism of gastric mucosal injury induced by macrophage-secreted inflammatory factors in H. pylori infection.
- To identify specific inflammatory factors and pathways involved in H. pylori-related gastritis.
Main Methods:
- Detected CCL3 expression and secretion in H. pylori-infected macrophages using RT-qPCR, Western blot, and ELISA.
- Assessed the impact of H. pylori-infected macrophage medium and CCL3 on gastric epithelial cell tight junctions and proliferation/apoptosis.
- Utilized dual-luciferase reporter and ChIP assays to identify CCL3 transcription factors and the JAK1-STAT1 pathway.
- Analyzed gastric mucosal inflammation and CCL3 expression in mice via H&E staining and immunohistochemistry.
Main Results:
- H. pylori infection increased macrophage secretion of CCL3.
- CCL3 and H. pylori-infected macrophage medium disrupted gastric epithelial tight junctions, an effect reversed by CCL3 inhibition.
- CCL3 induced P38 phosphorylation, contributing to tight junction disruption, with JAK1-STAT1 identified as the pathway regulating CCL3 transcription.
- In vivo, CCL3 exacerbated gastric mucosal injury and inflammation in mice.
Conclusions:
- H. pylori infection stimulates macrophages to secrete CCL3 through the JAK1-STAT1 pathway.
- CCL3 damages gastric epithelial tight junctions by phosphorylating P38.
- This pathway represents a novel mechanism in H. pylori-associated gastritis pathogenesis.
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