Research Update: Suppressing HCV After a Liver Transplant
Receiving a liver transplant may be the last chance at survival for someone whose Hepatitis C has progressed to end-stage liver disease. By removing a severely diseased liver with a healthy one, liver transplants appear to be an opportunity for someone with the Hepatitis C virus (HCV) to live a virus-free life.
However, nearly all liver transplant recipients become re-infected with Hepatitis C almost immediately following their surgery. In an attempt to prevent HCV from infecting their new liver, clinicians have been scrambling for solutions to this re-infection problem. By stepping outside the box of traditional HCV treatment, researchers from Japan have devised a novel, promising strategy to prevent Hepatitis C from inundating newly transplanted livers.
The number one cause of liver transplants in America, HCV has emerged as a premier health problem. Experts estimate that around 200 million people are infected with Hepatitis C worldwide. Usually progressing to a chronic illness, approximately 50 percent of those with HCV can be cured with the current standard of therapy, pegylated interferon and ribavirin.
Unfortunately, those who have had this virus for decades and do not respond to HCV therapy are vulnerable to progressive liver damage. If HCV wrecks enough havoc on the liver, liver failure and liver cancer are two potentially devastating outcomes. These are the people whose last resort might be a successful liver transplant.
A major challenge facing liver transplant recipients and their physicians is the recurrence of HCV infection. Within the first few days after transplant surgery, it is common for Hepatitis C viral loads to climb back up to the levels before the transplant. In fact, the viral load often exceeds pre-transplantation levels. Experts believe this is due to the suppression of the immune system that results from the immunosuppressive drugs used to prevent rejection of the transplanted liver.
Keeping this deficit of the immune response in mind, researchers from Hiroshima University in Japan conducted a trial to test the HCV suppression ability of transplanted immune cells. As published in the November 2009 edition of Journal of Clinical Investigation, the researchers performed the following sequence of events. They:
- Extracted immune cells known as lymphocytes from the donor livers before the transplant
- Activated the lymphocytes in vitro
- Injected the activated lymphocytes into the patients three days after they had received their liver transplants
The researchers found that this ingenious method worked, by keeping HCV levels low in most of the HCV-infected patients who received a liver transplant.
Numbering about one trillion in each individual, lymphocytes are small white blood cells that conduct most of the immune system’s actions. There are two main categories of lymphocytes: B cells and T cells.
- B cells – produce specific antibodies to infectious microorganisms.
- T cells – kill infectious microorganisms by destroying the body cells that are infected. In addition, T cells release chemicals called cytokines that initiate the immune response.
More research is required to investigate the clinical applicability of injecting lymphocytes to suppress Hepatitis C. However, the authors of this study believe they have developed a novel paradigm for the inhibition of viral replication in HCV-infected liver transplantation recipients.
http://thyroid.about.com/library/immune/blimm06.htm, Understanding the Immune
System, Mary J. Shomon, Retrieved January 7, 2010, about.com, 2010.
http://www.hcvadvocate.org/news/newsRev/2010/NewsRev-342.html#_Keeping_Hepatitis_C, Keeping Hepatitis C Virus at Bay after a Liver Transplant, Retrieved January 5, 2010, Hepatitis C Support Project, 2010.
http://www.jci.org/articles/view/38374, Adoptive immunotherapy with liver allograft-derived lymphocytes induces anti-HCV activity after liver transplantation in humans and humanized mice, Masahiro Ohira, et al, Retrieved January 5, 2010, Journal of Clinical Investigation, November 2009.
http://www.medsci.org/v03p0079.htm, Management of HCV Infection and Liver Transplantation,Thomas D. Schiano, Paul Martin, Retrieved January 7, 2010, International Journal of Medical Sciences, April 2006.