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Updated: Feb 24, 2026
Flow Cytometry Analysis of Immune Cells Within Murine Aortas
Published on: July 1, 2011
Neutrophils and aortic medial amyloid: mutually beneficial or a dangerous combination?
Alana Maerivoet1, Sarah Shirley1,2, Rebecca Price1
1Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom.
Introduction:
Amyloid deposition and inflammation are associated with many human diseases, with inflammatory cells found co-localised with amyloid in a range of tissues. Medin is the peptide that forms the most common localised amyloid in the aortic medial layer, yet remarkably little is known about its role in disease or factors that modulate its aggregation.
Methods:
We investigated the effect of neutrophil degranulation supernatants on medin fibril formation in vitro and explored the impact of inhibiting proteolytic components of neutrophil degranulation on aggregation using Thioflavin T fluorescence, transmission electron microscopy and cell viability analyses.
Results:
We showed that neutrophil supernatants reduced fibril formation of medin and its associated cell toxicity. Addition of inhibitors targeting MMPs (GM6001) and serine proteases (AEBSF) reversed the effects of neutrophils on fibril formation and cell toxicity. In contrast, inhibiting cysteine proteases using E64 showed comparable low ThT fluorescence and a lack of fibrils similar to what is observed for medin in the presence of neutrophil supernatants alone. However, despite appearing comparable to neutrophils alone, species produced showed significantly increased cell toxicity of up to 60% (P<0.0001).
Discussion:
This data has implications for understanding the role of neutrophil-mediated inflammation in medin-associated pathologies and provides avenues to explore for future therapeutic intervention.
Insights
Neutrophil degranulation products inhibit medin amyloid fibril formation and associated toxicity. However, inhibiting cysteine proteases unexpectedly increased medin
Area of Science:
- Biochemistry
- Cell Biology
- Pathology
Background:
- Amyloid deposition and inflammation are linked in various human diseases.
- Medin peptide forms common amyloid in the aortic medial layer, but its disease role is unclear.
Purpose of the Study:
- Investigate neutrophil degranulation effects on medin fibril formation.
- Explore inhibition of neutrophil proteases on medin aggregation.
Main Methods:
- In vitro medin fibril formation assays.
- Thioflavin T fluorescence and transmission electron microscopy.
- Cell viability analyses.
Main Results:
- Neutrophil supernatants reduced medin fibril formation and toxicity.
- MMP and serine protease inhibitors reversed these effects.
- Cysteine protease inhibition showed low fibril formation but increased cell toxicity.
Conclusions:
- Neutrophil-mediated inflammation influences medin-associated pathologies.
- Protease activity modulation offers therapeutic intervention strategies for medin-related diseases.
