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Published on: January 5, 2017
GZMA suppressed GPX4-mediated ferroptosis to improve intestinal mucosal barrier function in inflammatory bowel
Rongwei Niu1,2, Jiaoli Lan3,4, Danxia Liang5
1The First Affiliated Hospital of Jinan University, Jinan University, Guangzhou, China.
Insights
Granzyme A (GZMA) enhances intestinal barrier function by promoting epithelial cell differentiation and inhibiting ferroptosis. This finding offers a potential therapeutic strategy for inflammatory bowel disease (IBD).
Area of Science:
- Immunology
- Gastroenterology
- Cell Biology
Background:
- Decreased colonic CD8+CD39+ T cells and granzyme A (GZMA) are observed in pediatric-onset colitis and inflammatory bowel disease (IBD).
- Impaired intestinal barrier function is a hallmark of IBD.
- The specific role of GZMA in regulating intestinal barrier function was previously unknown.
Purpose of the Study:
- To investigate the influence of GZMA on intestinal epithelial barrier function.
- To elucidate the underlying molecular mechanisms by which GZMA modulates barrier integrity.
- To evaluate the therapeutic potential of GZMA in a colitis model.
Main Methods:
- In vivo and in vitro assays including Western blotting, qPCR, immunofluorescence, and intestinal organoid cultures.
- Permeability assays to assess barrier function.
- Molecular techniques such as luciferase assays, immunoprecipitation, and subcellular fractionation to identify mechanisms.
Main Results:
- GZMA, secreted by CD8+CD39+ T cells, enhances intestinal epithelial barrier function by upregulating Occludin (OCLN) and Zonula Occludens-1 (ZO-1) expression.
- This effect is mediated by enhanced CDX2-driven cell differentiation, which is linked to glutathione peroxidase 4 (GPX4)-induced ferroptosis inhibition.
- GZMA inhibits PDE4B, activating the cAMP/PKA/CREB pathway, leading to increased CREB nuclear translocation and GPX4 transactivity, ultimately alleviating DSS-induced colitis.
Conclusions:
- GZMA plays a crucial role in promoting intestinal epithelial cell differentiation and improving barrier function.
- Targeting GZMA presents a promising therapeutic avenue for patients suffering from IBD.
- The findings reveal a novel mechanism involving GZMA in maintaining intestinal homeostasis.
Background:
Our previous study has demonstrated a decreased colonic CD8+CD39+ T cells, enrichment of granzyme A (GZMA), was found in pediatric-onset colitis and inflammatory bowel disease (IBD) characterized by impaired intestinal barrier function. However, the influence of GZMA on intestinal barrier function remains unknown.
Methods:
Western blotting(WB), real-time PCR (qPCR), immunofluorescence (IF) and in vitro permeability assay combined with intestinal organoid culture were used to detect the effect of GZMA on intestinal epithelial barrier function in vivo and in vitro. Luciferase, immunoprecipitation (IP) and subcellular fractionation isolation were performed to identify the mechanism through which GZMA modulated intestinal epithelial barrier function.
Results:
Herein, we, for the first time, demonstrated that CD8+CD39+ T cells promoted intestinal epithelial barrier function through GZMA, leading to induce Occludin(OCLN) and Zonula Occludens-1(ZO-1) expression, which was attributed to enhanced CDX2-mediated cell differentiation caused by increased glutathione peroxidase 4(GPX4)-induced ferroptosis inhibition in vivo and in vitro. Mechanically, GZMA inhibited intestinal epithelial cellular PDE4B activation to trigger cAMP/PKA/CREB cascade signaling to increase CREB nuclear translocation, initiating GPX4 transactivity. In addition, endogenous PKA interacted with CREB, and this interaction was enhanced in response to GZMA. Most importantly, administration of GZMA could alleviate DSS-induced colitis in vivo.
Conclusion:
These findings extended the novel insight of GZMA contributed to intestinal epithelial cell differentiation to improve barrier function, and enhacement of GZMA could be a promising strategy to patients with IBD.
