Jun 25, 2014 2:00 PM by By Dennis Thompson
WEDNESDAY, June 25, 2014 (HealthDay News) -- The liver-damaging hepatitis C virus may come with an unexpected benefit for patients who need a liver transplant due to the infection, a new European study reports.
The virus appears to restrain a dangerous immune system response that can otherwise cause the body to reject the new liver, according to findings published June 25 in Science Translational Medicine.
This effect allowed about half of a small group of liver transplant patients to stop taking drugs that suppress their immune system, said lead author Felix Bohne, a postdoctoral fellow with the Institute of Virology at the Technical University of Munich Hemholtz Center Munich, Germany.
"It is always a hard thing to translate results from clinical studies into the everyday treatment of patients, but our study clearly shows that hepatitis C-infected liver recipients can discontinue the immunosuppressive medication," Bohne said.
Hepatitis Foundation International (HFI) called the research "encouraging news for people who may need a liver transplant."
"This is exciting research that shows the hepatitis virus changes the immune system in such a way to protect these liver transplants from being rejected by the body," said Dr. Gregory Pappas, medical director for HFI. "This is good news for many of HFI's constituents and those who will need a liver transplant and/or who have been infected with hepatitis C."
Doctors must typically use immunosuppressive drugs to help a body accept a new organ, but these medications often do more harm than good for hepatitis C patients who receive a new liver, experts say.
In background information supplied with the study, the researchers explained that because the immune system is suppressed by medications, hepatitis C actually flourishes after a transplant, causing rapid damage to the new liver.
However, if the immune-suppressing drugs are not given, hepatitis C appears to help a liver recipient accept the new organ -- even better than immunosuppressive medications would.
All this is due to a common viral trick that hepatitis C uses to avoid getting spotted by the immune system. According to the new study, the virus "rewires" immune cells to reduce their function -- essentially performing the immune-squelching work that immunosuppressive drugs do.
"This is part of the virus' immune evasion strategy and can be observed in a part of patients developing chronic hepatitis C," Bohne said.
The result is an environment in which immune response is blunted against the replacement liver because hepatitis C has taught the body to ignore the new organ.
In a study of 34 people with hepatitis C who received a new liver, Bohne and his colleagues found that 17 were able to stop taking their immunosuppressive medications without suffering organ rejection.
Might the same process occur with other infectious viruses? Bohne is doubtful. He said that while other viruses can suppress the immune response, few focus their efforts on one organ the way that hepatitis C focuses on the liver.
Dr. Thomas Schiano, medical director of liver transplant for Mount Sinai Health System, said the very small study "does give us some confidence as to us to be able to wean people off of immunosuppression."
But he added that new breakthroughs in hepatitis C treatment may make the point moot, anyway.
"Effective new medicines are probably going to make this not as pertinent," Schiano said. "If we are able to get rid of the hepatitis C in a majority of patients, that will provide further confidence to transplant surgeons to get patients off of immunosuppression."
A second, related study in the same journal issue found that laboratory-engineered immune cells can help treat serious viral infections that threaten to cause rejection in organ transplant patients.
A team led by Dr. Ann Leen, of Texas Children's Hospital in Houston, said they've developed a technique to rapidly produce immune cells capable of fighting of up to five different viruses known to cause organ rejection, including Epstein-Barr virus and herpes virus.
The engineered cells eliminated nearly all viruses from a small group of patients, the researchers reported.
"These viruses are a big source of graft [new organ] failure. This is something clearly worth exploring further," Schiano said. "The cost associated with this would be mitigated by all the money we spend to protect against infection."
For more on hepatitis C, visit the U.S. National Library of Medicine.