Bilirubin, produced in the liver, is known for causing people’s skin to turn yellow in jaundice. At high levels bilirubin can cause brain damage in newborns, but bilirubin could be harnessed for benefits not recognized in the past.
Hopkins scientists recently determined that the toxic bilirubin molecule can also be beneficial as an antioxidant. In last fall’s Proceedings of the National Academy of Sciences, the research team reported that bilirubin and the enzyme that makes it apparently provide potent protection for the body against oxidative damage. This finding may one day help improve the treatment of stroke, heart attack and even cognitive decline after heart bypass surgery.
Solomon Snyder, M.D., director of Neuroscience at Johns Hopkins School of Medicine, spearheaded the study, which was led by M.D./Ph.D. candidate David Barañano. “So potent an antioxidant is bilirubin that it displaces glutathione, the molecule believed for 80 years to be the most important cellular anti-oxidant,” says Snyder.
“There are some very elegant studies in the literature that tie slightly elevated bilirubin levels to better alertness in newborns, a lower risk of coronary artery disease and cancer in adults, and less damage from stroke in animal models. But these findings went against what people thought they knew about bilirubin, and the results were largely shrugged off,” Snyder adds. “Now they make sense.”
To reap the benefits of bilirubin’s power to protect cells, researchers could develop agents that stimulate its release from blood cells, that temporarily prevent its clearance from the body, or that otherwise elevate the amount of bilirubin in the body. However, whether the approach would reduce cellular damage from heart attack or stroke, for example, remains to be seen.
Authors on the study are Barañano, Snyder and Mahil Rao of the Johns Hopkins School of Medicine; and Christopher Ferris, formerly of Hopkins and now at Vanderbilt University School of Medicine. The studies were funded by the U.S. Public Health Service
