Leprosy bacteria offers hope to repair damaged livers

Leprosy bacteria. Computer illustration of Mycobacterium leprae bacteria, the Gram-positive rod-shaped bacteria which cause the disease leprosy.
Leprosy bacteria – could it hold the key to repairing livers? (Getty) (KATERYNA KON/SCIENCE PHOTO LIBRARY via Getty Images)

Leprosy is one of the world’s oldest diseases but it could offer hope to people suffering from liver damage, a new study has shown.

University of Edinburgh scientists say that the parasites associated with leprosy can reprogramme cells to increase the size of a liver in adult animals without causing damage, scarring or tumours.

The researchers say it might be possible to adapt this natural process to renew ageing livers and increase healthspan – the length of time living disease-free – in humans.

Experts say it could also help regrow damaged livers.

Liver diseases currently result in two million deaths a year worldwide.

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This would reduce the need for transplantation, which is currently the only curative option for people with end-stage scarred livers.

Professor Anura Rambukkana, lead author from University of Edinburgh's Centre for Regenerative Medicine, said: "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."

Previous studies promoted the regrowth of mouse livers by generating stem cells and progenitor cells ≠ the step after a stem cell that can become any type of cell for a specific organ — via an invasive technique that often resulted in scarring and tumour growth.

Edinburgh researchers built on their previous discovery of the partial cellular reprogramming ability of the leprosy-causing bacteria, Mycobacterium leprae.

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Working with the US Department of Health and Human Services in Baton Rouge, Louisiana, the team infected 57 armadillos – a natural host of leprosy bacteria – with the parasite and compared their livers with those of uninfected armadillos.

They found that the infected animals developed enlarged, yet healthy and unharmed, livers with the same vital components, such as blood vessels, bile ducts and functional units known as lobules, as the uninfected and resistant armadillos.

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

They also discovered several indicators that the main kinds of liver cells – known as hepatocytes – had reached a "rejuvenated" state in the infected armadillos.

Livers of the infected armadillos also contained gene expression patterns – the blueprint for building a cell – similar to those in younger animals and human foetal livers.

Genes related to metabolism, growth and cell proliferation were activated and those linked with ageing were downregulated, or suppressed.

Scientists think this is because the bacteria reprogramed the liver cells, returning them to the earlier stage of progenitor cells, which in turn became new hepatocytes and grew new liver tissues.

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