The Edinburgh scientists from the University's Centre for Inflammation Research, in collaboration with colleagues from the University of Southampton and Cincinnati, Ohio have, for the first time, identified two separate populations of immune cells --macrophages--in the liver. One group of macrophages causes scarring to the liver, but the next wave of immune cells, produced only a few days later, change function to break down and reabsorb the scarring. These findings, published in the January edition of Journal of Clinical Investigation, will help doctors to understand the mechanisms by which the liver is damaged and repaired and may lead to future treatments.
Researcher Dr Jeremy Duffield explained: "The links between the immune system, inflammation and scarring in the liver have not been well understood, and this has hindered progress in finding ways to prevent and repair liver damage. Now that we have shown how the macrophages work, we aim to find out how to create, activate and de-activate these cells to make them repair, rather than damage, liver tissue."
He added: "Cirrhosis, commonly, but not always, caused by alcohol consumption, can lead to liver failure. At a time when outcomes for other diseases, such as cancers and heart trouble, have made dramatic gains, liver damage --described as the new plague of the 21st century --has yet to be understood and in turn, to become treatable. More women in the UK now die of liver failure than do of cancer of the cervix.
"There has been a fourfold increase in the number of men aged 45-54 dying of cirrhosis since 1970 and a threefold increase in women of the same age group. Liver failure is also rapidly increasing in younger people with the deaths in the UK of 500 men and 300 women aged 25-44, in 2003."
Professor John Iredale of the University of Southampton said: "We are facing a huge increase in the numbers of patients with advanced liver fibrosis (scarring) and cirrhosis (end stage scarring of the liver). Currently, we have no effective treatment for liver cirrhosis which is associated with internal bleeding, liver failure and the development of primary liver cancer. There is a huge imperative to develop new approaches to the treatment of liver scarring. Exciting insights such as these will inform the design of future therapies."
Further research into macrophages is set to follow and scientists will explore the role of these immune-system cells in damage and repair to other organs, including the kidney.