Cardiac lipolysosome-like structures in IL-4 receptor α-deficient BALB/c mice with heart failure

Authors

• AS Gozalo
• WR Elkins

Abstract

First described in 1974 in hamsters by Nehemiah and Novikoff, lipolysosomes (lysosomes containing lipid droplets) are usually found in hepatocytes of patients with various forms of hepatic injury and in patients with Wolman's or Wilson's disease. Lipolysosomes are associated with excess lipid accumulation result of impaired lipid metabolism, most commonly in liver cells, and its presence in other cells or organs is very uncommon. A retrospective study of cardiac failure in IL-4 receptor α-deficient BALB/c mice showed animals with cardiac dilatation had ultrastructural defects in the myocardial intercalated discs, myofibrillar and, occasional, sarcomere lysis. Interestingly, some animals had prominent single-membrane, round to oval, structures containing irregular smaller droplets, mostly translucent, surrounded by lipofuscin-like electrondense material measuring from 700 nm to 4,000 nm and associated to mitochondria. The structures resembled lipolysosomes. To our knowledge, there are no reports of cardiac lipolysosomes in animals or humans. Lipids are the primary substrate for cardiac energy production and heart failure can alter cardiac lipid metabolism which may have contributed to the presence of the lipolysosome-like structures in the affected mice. Further studies are required to characterize the observed structures and its potential role in heart failure.

Scientific Focus Area: Cell Biology

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