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Analysis of β-Amyloid-induced Abnormalities on Fibrin Clot Structure by Spectroscopy and Scanning Electron Microscopy
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Apolipoprotein A-IV fibrils: structural diagnosis of mixed cardiac amyloidosis

Shintaro Aibara1, Astrid Kassner2, Edmond Wong1,3

  • 1Protein Sciences, Structure, and Biophysics, Discovery Sciences, R&D, AstraZeneca, Cambridge, UK.

Nature Communications
|October 20, 2025
PubMed

Insights

Misfolded apolipoprotein A-IV (ApoAIV) can form amyloid fibrils in the heart, contributing to cardiac amyloidosis (CA). Researchers identified ApoAIV alongside transthyretin (TTR) in mixed CA cases, emphasizing the need for broad-spectrum treatments.

Area of Science:

  • Cardiovascular Medicine
  • Protein Misfolding Diseases
  • Biochemistry

Background:

  • Cardiac amyloidosis (CA) involves misfolded protein deposits in the heart's extracellular matrix.
  • Apolipoprotein A-IV (ApoAIV) has known fibrillogenic properties linked to CA.
  • Transthyretin (TTR) is a common cause of cardiac amyloidosis.

Purpose of the Study:

  • To determine the structural characteristics of apolipoprotein A-IV (ApoAIV) amyloid deposits in cardiac tissue.
  • To investigate the co-occurrence of ApoAIV and transthyretin (TTR) amyloids in patients with cardiac amyloidosis.
  • To underscore the clinical implications of mixed amyloidosis in CA diagnosis and treatment.

Main Methods:

  • Structural analysis of amyloid fibrils from patient heart biopsies.
  • Histological examination to identify coexisting amyloid types.
  • Clinical case review of patients with mixed cardiac amyloidosis.

Main Results:

  • The study reports the detailed structure of ApoAIV amyloid fibrils.
  • ApoAIV amyloids were found to coexist with TTR amyloids in the same patient hearts.
  • These mixed CA cases were previously undetected, suggesting a diagnostic challenge.

Conclusions:

  • ApoAIV is a novel fibril protein implicated in cardiac amyloidosis.
  • Mixed amyloidosis involving ApoAIV and TTR is more common than previously recognized.
  • Development of broad-spectrum anti-amyloid therapies is crucial for managing diverse CA presentations.

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