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Induction of macrophage pyroptosis-related factors by pathogenic E. coli high pathogenicity island (HPI) in Yunnan
Chunlan Shan1, Shushu Miao2, Chaoying Liu1
1College of Animal Science and Technology, Yunnan Agricultural University, Kunming, 650201, China.
Background:
Pyroptosis plays a pivotal role in the pathogenesis of many inflammatory diseases. The molecular mechanism by which pyroptosis is induced in macrophages following infection with pathogenic E. coli high pathogenicity island (HPI) will be evaluated in our study.
Results:
After infection with the HPI+/HPI- strains and LPS, decreased macrophage cell membrane permeability and integrity were demonstrated with propidium iodide (PI) staining and the lactate dehydrogenase (LDH) assay. HPI+/HPI--infection was accompanied by upregulated expression levels of NLRP3, ASC, caspase-1, IL-1β, IL-18 and GSDMD, with significantly higher levels detected in the HPI+ group compared to those in the HPI- group (P < 0.01 or P < 0.05). HPI+ strain is more pathogenic than HPI- strain.
Conclusion:
Our findings indicate that pathogenic E. coli HPI infection of Saba pigs causes pyroptosis of macrophages characterized by upregulated expression of pyroptosis key factors in the NLRP3/ASC/caspase-1 signaling pathway, direct cell membrane pore formation, and secretion of the inflammatory factor IL-1β and IL-18 downstream of NLRP3 and caspase-1 activation to enhance the inflammatory response.
Insights
Pathogenic E. coli infection triggers pyroptosis in macrophages, a key inflammatory process. This study reveals how the high pathogenicity island (HPI) of E. coli drives this response, impacting inflammatory diseases.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Pyroptosis is a crucial inflammatory cell death pathway implicated in various diseases.
- Understanding pyroptosis induction by pathogenic Escherichia coli (E. coli) in macrophages is vital.
Purpose of the Study:
- To investigate the molecular mechanisms of pyroptosis in macrophages infected with pathogenic E. coli, focusing on the role of the high pathogenicity island (HPI).
Main Methods:
- Macrophage infection with HPI-positive (HPI+) and HPI-negative (HPI-) E. coli strains and lipopolysaccharide (LPS).
- Assessment of cell membrane integrity using propidium iodide (PI) staining and lactate dehydrogenase (LDH) assay.
- Quantification of key pyroptosis-related gene and protein expression levels (NLRP3, ASC, caspase-1, IL-1β, IL-18, GSDMD).
Main Results:
- Infection with both HPI+ and HPI- E. coli strains, as well as LPS, decreased macrophage cell membrane permeability and integrity.
- Upregulated expression of NLRP3, ASC, caspase-1, IL-1β, IL-18, and GSDMD was observed following HPI+ and HPI- infection.
- Significantly higher expression levels of these pyroptosis markers were found in the HPI+ group compared to the HPI- group, indicating greater pathogenicity of the HPI+ strain.
Conclusions:
- Pathogenic E. coli HPI infection induces macrophage pyroptosis in Saba pigs.
- This process involves the upregulation of key factors in the NLRP3/ASC/caspase-1 pathway.
- Pyroptosis leads to cell membrane pore formation and secretion of IL-1β and IL-18, amplifying the inflammatory response.
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