PITTSBURGH, Dec. 7, 2016 - Researchers from the University of Pittsburgh School of Medicine and UPMC have engineered a protein that reverses carbon monoxide (CO) poisoning in mice, a discovery that could potentially lead to the creation of the first antidote in humans to the often deadly poisoning, according to research published today in the journal Science Translational Medicine.
CO poisoning is responsible for more than 50,000 emergency room visits in the United States annually, and is one of the leading global causes of poisoning death. A colorless, odorless gas, CO is extremely effective at replacing oxygen molecules in hemoglobin, the oxygen carrying protein in blood. CO exposure also results in debilitating effects on the body and the brain, including cognitive deficits that in some cases can persist months or years after a poisoning event.
"Despite being the most common poisoning worldwide, we still do not have an effective antidote for CO exposure," said Mark T. Gladwin, M.D., chair of medicine, Pitt School of Medicine, Dr. Jack D. Myers Professor of Internal Medicine, and director of the Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute. "Our protein is extraordinarily effective at scavenging CO from the blood, and could potentially prove to be a significant advance in the treatment of CO poisoning."
Current treatment options for CO poisoning--administering 100 percent oxygen or using a pressurized hyperbaric chamber to administer oxygen at greater than normal air pressure--focus on trying to replace CO in blood with oxygen as quickly as possible. However, both these treatments are only moderately effective. Moreover, transporting patients to a hyperbaric chamber requires a significant amount of time, and many poisoned patients may not be stable enough for this therapy.
When studying neuroglobin (Ngb), a hemoglobin-like protein present in the brain, Gladwin and his team discovered it could bind CO with an unusually high affinity. Based on prior knowledge of how the protein works, researchers engineered a mutant version of the protein, called Ngb H64Q, that was an even better scavenger of CO.
In a purified sample of red blood cells infused with CO, they found that Ngb H64Q was 1,200 times faster at forcing CO to release itself from being bound to hemoglobin than just air alone. When tested in a mouse model of non-lethal CO poisoning, they found that Ngb H64Q was significantly better at removing CO from hemoglobin than 100-percent oxygen treatment. The normal half-life of CO in humans after poisoning (time it takes for half of the CO to be eliminated from the body) is 320 minutes, and even with 100-percent oxygen therapy, that time is 74 minutes. With the antidote therapy, the CO half-life was reduced to only 23 seconds.
In a mouse model with lethal levels of CO poisoning, seven out of eight mice treated with Ngb H64Q (87.5 percent) survived the duration of the experiment, while 10 percent or less survived in the control groups. Additionally, the antidote restored blood pressure and improved the amount of oxygen that was present in tissues, suggesting that Ngb H64Q works by scavenging CO from hemoglobin and allowing oxygen to bind in its place, thus restoring normal oxygen delivery.
Importantly, CO bound to Ngb H64Q was detected in the urine of mice shortly after treatment, which indicated that the rodents were able to excrete the antidote from the body without any major toxic effects.
"If approved, this antidote could be rapidly administered to victims in the field, eliminating costly delays that occur with current treatment options," Gladwin said. "We still need extensive safety and efficacy testing before an antidote is available on the shelf, but our early results are very promising."
Researchers plan to scale up their safety and efficacy testing in animal models and hope to advance to clinical trials within the next few years.
Ivan Azarov, Ph.D., Ling Wang, M.D., Ph.D., and Jason J. Rose, M.D., all from Pitt, were the study's lead authors. Additional contributors included Qinzi Xu, M.D., Xueyin N. Huang, Ph.D., Ying Wang, Ph.D., Lanping Guo, Ph.D., Charles F. McTiernan, Ph.D., Christopher P. O'Donnell, Ph.D., Sruti Shiva, Ph.D., and Jesús Tejero, M.D., Ph.D., all of Pitt; and Chen Liu, Ph.D., Kamil B. Ucer, Ph.D., Andrea Belanger, Ph.D., and Daniel B. Kim-Shapiro, Ph.D., of Wake Forest University.
The study was supported in part by the National Heart, Lung, and Blood Institute SMARTT (Science Moving towArd Research Translation and Therapy) Program, the Institute for Transfusion Medicine and the Hemophilia Center of Western Pennsylvania; and National Institutes of Health grants F32 HL132418, R01 HL111706, R01 GM113816, R21 ES027390, R01 HL058091, R01 HL098032, R01 HL125886, P01 HL103455, T32 HL110849 and T32 HL007563.
For access to a video interview with Gladwin, please contact Lawerence Synett at SynettL@upmc.edu or 412-302-4127.
About the University of Pittsburgh School of Medicine
As one of the nation's leading academic centers for biomedical research, the University of Pittsburgh School of Medicine integrates advanced technology with basic science across a broad range of disciplines in a continuous quest to harness the power of new knowledge and improve the human condition. Driven mainly by the School of Medicine and its affiliates, Pitt has ranked among the top 10 recipients of funding from the National Institutes of Health since 1998. In rankings recently released by the National Science Foundation, Pitt ranked fifth among all American universities in total federal science and engineering research and development support.
Likewise, the School of Medicine is equally committed to advancing the quality and strength of its medical and graduate education programs, for which it is recognized as an innovative leader, and to training highly skilled, compassionate clinicians and creative scientists well-equipped to engage in world-class research. The School of Medicine is the academic partner of UPMC, which has collaborated with the University to raise the standard of medical excellence in Pittsburgh and to position health care as a driving force behind the region's economy. For more information about the School of Medicine, see http://www.medschool.pitt.edu.
A world-renowned health care provider and insurer, Pittsburgh-based UPMC is inventing new models of patient-centered, cost-effective, accountable care. It provides nearly $900 million a year in benefits to its communities, including more care to the region's most vulnerable citizens than any other health care institution. The largest nongovernmental employer in Pennsylvania, UPMC integrates 60,000 employees, more than 20 hospitals, more than 500 doctors' offices and outpatient sites, and a more than 3 million-member Insurance Services Division, the largest medical and behavioral health services insurer in western Pennsylvania. Affiliated with the University of Pittsburgh Schools of the Health Sciences, UPMC ranks No. 12 in the prestigious U.S. News & World Report annual Honor Roll of America's Best Hospitals. UPMC Enterprises functions as the innovation and commercialization arm of UPMC while UPMC International provides hands-on health care and management services with partners in 12 countries on four continents. For more information, go to UPMC.com.
Contact: Lawerence Synett
Contact: Arvind Suresh
Science Translational Medicine