IUBMB-Life 2019: Vitamin E-Regulatory Roles

Distribution and Utilization of Vitamin E in Different Organs of Wild Bats from Different Food Groups

In this work, we examined the levels of vitamin E in the heart, liver, and kidneys of four species of adult male bats with distinct feeding habits. Our results indicate consistent vitamin E levels in the heart across all four bat species, suggesting the presence of regulatory mechanisms. Additionally, the liver displayed notably higher vitamin E levels in nectarivorous and frugivorous bats, while hematophagous bats exhibited lower levels, indicating a link between dietary intake and liver vitamin E levels. Furthermore, correlation analysis provided additional insights into the relationships between vitamin E and key antioxidant parameters in the livers of bats. On the other hand, no correlation was observed between vitamin E and key antioxidant parameters in the heart. Intriguingly, vitamin E was not detected in the kidneys, likely due to physiological factors and the prioritization of vitamin E mobilization in the heart, where it serves critical physiological functions. This unexpected absence of vitamin E in bat kidneys highlights the unique metabolic demands and prioritization of vitamin mobilization in wild animals like bats, compared to conventional animal models. These findings provide insight into the intricate distribution and utilization of vitamin E in bats, emphasizing the influence of dietary intake and metabolic adaptations on vitamin E levels in different organs.

Lester Packer and Vitamin E: Editorial

The inspiring ideas of Professor Lester Packer (1929-2018) substantially enriched our understanding of biological systems. One of the most important contributions of Lester is the role of vitamin E in biological membranes. Lester started early in the 1970s with the development and use of a preparatory technique for electron microscopy of biological membranes, the "freeze fracture." This made it possible to detect inner and outer membranes of mitochondria as well as associated compounds in other biological organelles. Lester also considered the effect of tocols on entire animals and thereby initiated the field of exercise biology. An important finding was the loss of vitamin E and of muscle mitochondria after exhaustive exercise. In the 1990s, he and his group worked on the intermembrane exchange and membrane stabilization by tocols. They also determined the specific activities of various tocols including tocotrienols. In the later years they embarked on the role of vitamin E in redox signaling and gene expression, topics fundamental to our understanding of the role of vitamin E in membranes and in general. Lester, his group, and international guests tried to answer the still open question how vitamin E protects biomembranes. The numerous possibilities they offered will help to find a final solution. Lester always engaged himself at the forefront of science and in scientific exchange on meetings and in societies. Antioxid. Redox Signal. 39, 771-776.

alpha-Tocopherol supplementation reduces inflammation and apoptosis in high cholesterol mediated nonalcoholic steatohepatitis

Inflammation and apoptosis signaling are crucial steps in the progression from nonalcoholic fatty liver disease (NAFLD) to nonalcoholic steatohepatitis (NASH). Alpha-tocopherol, the most active form of vitamin E, is an important modulator of signaling mechanisms, but its involvement to cholesterol-induced NASH pathogenesis remains poorly defined. Herein we have reported a novel effect of α-tocopherol in the transition from hepatic steatosis to NASH. High cholesterol diet alone (without α-tocopherol) in rabbits elevated NASH development as indicated by increased inflammatory response, apoptotic activity and liver fibrosis. Such elevation results from induction of signaling mechanisms since the expressions of IL1β, phospho c-Jun/c-Jun ratio, JNK, caspase 9, CHOP and Bax were increased, and recruitment of macrophage, α-smooth muscle actin (α-SMA) and COL1A1 into the liver tissue were induced. Alpha-tocopherol supplementation inhibited inflammatory response, apoptosis and fibrosis development without affecting lipid accumulation in high cholesterol-induced NASH. Specifically, α-tocopherol lowered the inflammatory level as observed by reduced macrophage infiltration and JNK/c-Jun signaling. Lower inflammatory status co-occurred with the reduction of CHOP and Bax expressions as well as fibrosis-related COL1A1 and α-SMA levels. Taken together, α-tocopherol supplementation inhibits cholesterol-induced NASH development by lowering JNK/c-Jun/inflammation axis in addition to JNK/CHOP/apoptosis signaling, which might contribute to resistance against NAFLD/NASH transition.