Renalase deficiency aggravates ischemic myocardial damage

Area of Science:

• Cardiovascular Science
• Nephrology
• Biochemistry

Background:

• Chronic kidney disease (CKD) significantly elevates cardiovascular complication risk, exceeding traditional risk factor explanations.
• Renalase, an oxidase metabolizing catecholamines, is reduced in CKD patients.
• The precise role of renalase in CKD-associated cardiovascular pathology remains unclear.

Purpose of the Study:

• To investigate the functional role of renalase in cardiovascular complications associated with CKD.
• To elucidate the underlying mechanisms of renalase's cardioprotective effects.

Main Methods:

• Utilized a mouse model with renalase gene deletion (knockout) to study its effects on cardiovascular parameters.
• Assessed cardiac function, ischemia tolerance, and myocardial necrosis.
• Measured plasma catecholamines, blood urea nitrogen, creatinine, aldosterone, and NADH oxidase activity.
• Investigated the impact of renalase deficiency on NAD/NADH ratios in cardiac tissue.
• Administered recombinant renalase to rescue the observed cardiac phenotype.

Main Results:

• Renalase deficiency led to elevated plasma catecholamines and hypertension in knockout mice.
• Despite normal systolic function and mild hypertrophy, knockout mice exhibited threefold more severe myocardial necrosis after ischemia compared to wild-type mice.
• Cardiac tissue in knockout mice showed a decreased ratio of oxidized (NAD) to reduced (NADH) nicotinamide adenine dinucleotide.
• Plasma NADH oxidase activity was also reduced in knockout mice.
• Treatment with recombinant renalase fully restored normal cardiac function and reduced ischemia-induced damage.

Conclusions:

• Renalase plays a critical role in protecting the heart against ischemic injury, independent of traditional cardiovascular risk factors.
• Reduced renalase function in CKD contributes to cardiovascular pathology through mechanisms involving catecholamine metabolism and cellular energy balance (NAD/NADH ratio).
• Therapeutic replacement of renalase holds potential for mitigating cardiac complications in CKD and other renalase-deficient states.