Leprosy may hold anti-aging secrets

Scientists in the United Kingdom may have uncovered a new mechanism that slows the aging process, and the secret is hidden within one of the world's most ancient diseases.

Edinburgh University researchers have discovered that Mycobacterium leprae, the bacteria that causes leprosy, can rejuvenate liver cells in armadillos, which are natural hosts of the disease, leading to an increase in both the health and size of the liver.

To achieve this, the bacteria somehow activates genes within liver cells that are related to metabolism, growth, and cell proliferation. The bacteria also downregulates, or suppresses, genes linked to aging, said authors of the study, which was published in the journal Cell Reports Medicine.

If further research can identify the specific mechanism employed by the leprosy bacteria, it could have real implications in treating liver diseases, and may also unlock new avenues for slowing down the aging process.

"If we can identify how bacteria grow the liver as a functional organ without causing adverse effects in living animals, we may be able to translate that knowledge to develop safer therapeutic interventions to rejuvenate aging livers and to regenerate damaged tissues," said Anura Rambukkana, a professor of regenerative medicine at Edinburgh University, who led the research.

Previous attempts to improve liver health using stem cells have often led to scarring and tumors, but the bacteria-induced rejuvenation caused no damage to the organs.

Leprosy, a chronic infection that affects almost 250,000 people worldwide, is one of the oldest recorded diseases. Ancient skeletal evidence from India dates human infection back to at least 2000 BCE, and scholars believe an ancient Egyptian scroll from 1500 BCE contains one of the first known references to the affliction.

In humans, the disease can cause damage to skin tissue, nerves, eyes, and respiratory tract.

For millenia, affected people have suffered social stigma, but transmission rates are exceedingly low and infection can now be cured if there is an early diagnosis. Leprosy naturally infects humans as well as other animals, including monkeys and armadillos.

Working with the United States Department of Health and Human Services in Baton Rouge, Louisiana, the Edinburgh team infected 57 armadillos with the parasite and compared their livers with those of uninfected armadillos and with those that were found to be resistant to infection.

They found the infected animals developed enlarged — yet healthy and unharmed — livers with the same components, including blood vessels and bile ducts, as the uninfected and resistant armadillos.

The team of researchers believes the bacteria 'hijacked' the inherent regenerative ability of the liver to increase the organ's size and, therefore, to provide it with more cells with which to increase.

"This is an exciting study," said Darius Widera, an associate professor in stem cell biology at the University of Reading, who was not involved in the research. "Overall, the results could pave the way for new therapeutic approaches to the treatment of liver diseases such as cirrhosis … However, as the research has been done using armadillos as model animals, it is unclear if and how these promising results can translate to the biology of the human liver."