Proinflammatory consequences of transgenic fas ligand expression in the heart

Area of Science:

• Immunology
• Cardiovascular Biology
• Molecular Biology

Background:

• Fas ligand (FasL) expression can induce immune privilege or tissue destruction.
• The role of FasL in striated muscle, particularly the heart, is controversial.
• Understanding FasL's impact on cardiac tissue is crucial for cardiovascular and immunological research.

Purpose of the Study:

• To investigate the consequences of cardiomyocyte-specific Fas ligand (FasL) expression in transgenic mice.
• To determine if enforced FasL expression in the heart leads to tissue destruction or other inflammatory responses.
• To elucidate the relationship between FasL, Fas, and cardiac tissue homeostasis.

Main Methods:

• Generation of transgenic mice with cardiomyocyte-specific FasL expression.
• Assessment of leukocyte infiltration, apoptosis, and necrosis in Tg hearts.
• Evaluation of cardiac function, hypertrophy, gene expression, and cytokine induction.

Main Results:

• Transgenic mice exhibited healthy phenotypes with mild leukocyte infiltration in the heart.
• Despite coexpression of Fas and FasL, no myocardial apoptosis or necrosis was observed.
• Cardiac hypertrophy, interstitial fibrosis, and altered gene expression, including cytokine induction, were noted.
• The observed proinflammatory effects were transgene-dose dependent.

Conclusions:

• Cardiac-specific FasL expression induces leukocyte infiltration and hypertrophy without severe tissue destruction.
• FasL expression level and tissue-specific microenvironmental factors modulate its proinflammatory consequences.
• The heart may possess unique mechanisms to mitigate FasL-induced tissue damage compared to other tissues.