Leprosy is an ancient infection, common in biblical times, causing such disfiguring disease that sufferers were exiled to isolated colonies miles from anywhere.
But now it seems that the destructive bacterium that causes it, mycobacterium leprae, could be a force for good – able to grow and regenerate a vital organ.
Scientists have discovered that leprosy bacteria can reprogramme cells to increase the size of a liver in mature animals without causing damage, scarring or tumours.
Could this be harnessed to renew ageing livers and increase their health span in human beings?
Experts say it could also help regrow damaged livers, thereby reducing the need for transplantation, which is the only curative option for people with end-stage diseased livers at present.
Previous studies had seen the regrowth of mouse livers via an invasive technique, often resulting in scarring and tumour growth.
But Edinburgh researchers have built on their previous discovery of this cellular reprogramming ability.
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 bug. They then compared their livers with those of uninfected armadillos and those found to be resistant to infection.
They found that the infected animals developed enlarged – yet healthy and unharmed – livers identical to the uninfected and resistant armadillos. How did the bacteria achieve this?
The team believe the bacteria “hijacked” the inherent regenerative ability of the liver to increase the organ’s size, therefore giving it more cells where they could increase.
So the bacteria were being selfish and looking after themselves by providing more sustenance – and the liver benefitted accidentally. They also discovered the main kinds of liver cells –hepatocytes – were “rejuvenated” in the infected armadillos and gene activity became similar to those in younger animals.
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 reprogrammed the liver cells, returning them to the earlier stage of development, which then became new hepatocytes and grew new liver tissues.
Liver disease currently results in two million deaths a year worldwide but Professor Anura Rambukkana, at the University of Edinburgh’s Centre for Regenerative Medicine, is hopeful.
“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 ageing livers and to regenerate damaged tissues,” she says.
