Extracellular superoxide dismutase regulates cardiac function and fibrosis

Area of Science:

• Cardiology
• Biochemistry
• Pharmacology

Background:

• Extracellular superoxide dismutase (EC-SOD) is an antioxidant enzyme with known protective roles in the lungs and heart during ischemia.
• The specific function of cardiac EC-SOD under normal physiological conditions and in response to injury, particularly doxorubicin-induced cardiotoxicity, remains incompletely understood.
• Doxorubicin-induced cardiotoxicity is a significant clinical concern, primarily mediated by oxidative stress.

Purpose of the Study:

• To investigate the critical role of EC-SOD in maintaining normal cardiac function and protecting the heart against doxorubicin-induced oxidative stress, fibrosis, and apoptosis.
• To evaluate the therapeutic potential of the antioxidant metalloporphyrin AEOL 10150 in mitigating doxorubicin-induced cardiac damage.

Main Methods:

• Comparison of cardiac function, morphology, fibrosis, and inflammation between wild-type and EC-SOD-null mice treated with doxorubicin.
• Echocardiography was employed to assess cardiac function (e.g., fractional shortening, LV dimensions).
• Histological staining, Western blot analysis, and hydroxyproline assays were used to quantify myocardial fibrosis and inflammation.

Main Results:

• EC-SOD-null mice exhibited baseline cardiac structural abnormalities (LV wall thinning, increased LV end-diastolic dimensions) but normal function.
• Doxorubicin treatment led to significant cardiac dysfunction, increased apoptosis, fibrosis, and inflammatory cell infiltration in EC-SOD-null mice compared to wild-type controls.
• Administration of AEOL 10150 effectively abrogated doxorubicin-induced loss of cardiac function and showed a trend towards reducing fibrosis in both wild-type and EC-SOD-null mice.

Conclusions:

• EC-SOD is essential for normal cardiac morphology and function, providing crucial protection against doxorubicin-induced oxidative stress, fibrosis, and apoptosis.
• The antioxidant AEOL 10150 demonstrates significant efficacy in protecting cardiac function against doxorubicin-induced cardiotoxicity in vivo.
• These findings highlight EC-SOD and antioxidant therapies as potential targets for managing oxidant-induced cardiac fibrosis.