Inflammatory dilated cardiomyopathy in Abcg5-deficient mice

Area of Science:

• Cardiovascular Biology
• Genetics
• Immunology

Background:

• Dilated cardiomyopathy (DCM) in A/J mice is linked to the Abcg5 gene mutation (trac).
• Human Abcg5 mutations cause sitosterolemia, hypercholesterolemia, and atherosclerosis.
• The trac mutation leads to inflammation, myocyte degeneration, and fibrosis in mouse hearts.

Purpose of the Study:

• To investigate the role of the Abcg5 gene mutation in DCM development.
• To explore the impact of phytosterols on cardiomyopathy progression.
• To characterize the inflammatory and cellular mechanisms underlying DCM in this mouse model.

Main Methods:

• Genetic analysis of A/J mice with the trac mutation.
• Histological and transmission electron microscopy (TEM) of cardiac tissue.
• Dietary intervention studies with phytosterol-free diets.
• Studies using B- and T-cell-deficient mice (Rag1 null).

Main Results:

• A/J-trac/trac mice developed progressive inflammatory and fibrosing cardiomyopathy.
• Lifelong phytosterol-free diets prevented DCM in A/J-trac/trac mice.
• BALB/cByJ-trac/trac mice showed delayed DCM onset and reduced T cell infiltrates with diet changes.
• B- and T-cell-deficient trac/trac mice did not develop inflammatory infiltrates or DCM.

Conclusions:

• The trac/trac mouse model exhibits features of inflammatory DCM.
• Dietary phytosterols are critical for DCM development in this model.
• Myocardial T cell infiltration is a key driver of DCM progression.
• This model offers a novel platform for studying inflammatory DCM and fibrosis reversibility.