Do you know the principle of liver regeneration, Hansen’s disease?

There are only two animals on the planet that have Hansen’s disease (leprosy). One is human and the other is an armadillo surrounded by a hard carapace. The only two mammals with shells are the pangolin, which lives in Asia and Africa, and the armadillo, which lives in the Americas.

Hansen’s disease (Bacillus leprosy) has been found to maximize the ability of armadillos to regenerate liver tissue. This is the content reported by the scientific journal Science and the BBC on the basis of an article by a research group from the University of Edinburgh, Scotland, published in Cell Reports Medicine on the 15th (local time).

Hansen’s disease is caused by a bacterial infection (Hansen’s disease). In the past, it was considered an incurable disease, but nowadays it is a disease that can be cured by taking a single antibiotic targeting this bacterium, and the contagiousness disappears, and a prescription of combined antibiotics is used.

Researchers have found that when infected with leprosy, the armadillo’s liver becomes significantly enlarged. The liver is the body’s regenerative champion, regenerating itself after injury and disease. If one of the two kidneys in the human body is donated, a new kidney will not grow in its place. Even if two-thirds of the liver is cut off for donation, it will regenerate to its original size over time. Knowing the principle of liver regeneration can be helpful in treating patients with cirrhosis of the liver and other liver function impairments, but scientists still don’t know the principle.

Researchers led by Professor Anura Rambukana of the University of Edinburgh’s Center for Regenerative Medicine discovered nearly a decade ago that leprosy bacteria invade Schwann cells in the peripheral nervous system when they become active. It was the discovery that when leprosy bacteria invade and become established in Schwann cells, they stimulate the cells to revert to a less mature state of development, making them similar to stem cells.

At the time, the research was incomplete because it had been done on cells from standard laboratory animals, such as mice, that don’t develop leprosy. For this reason, Professor Rambucana, who had struggled to stay awake at night, called a laboratory in Louisiana, US, that raised armadillos and asked if any abnormalities had been found in the organs of armadillos with leprosy.

The answer that came was, “I see the liver is getting bigger,” and Professor Rambukana jumped up and liked it.

A new study confirms this observation. The livers of leprosy-infected armadillos are about a third larger than those of uninfected armadillos, the researchers found. Furthermore, it was found that the liver did not grow promiscuously, but grew with the exact number of liver lobes and anatomical features that maintain the honeycomb arrangement of the subunits.

Tumors or scars can form in liver disease. When tumors and scars occur, liver function disorders occur. However, two signs were not found in the livers of leprosy-infected armadillos. In addition, some liver proteins were analyzed and liver function was normal.

To study how armadillo livers enlarge, the researchers measured gene activity in leprosy-infected and uninfected animals. It was observed that the liver cells of armadillos harboring the Hansen’s disease germ were transformed into stem cells like the Schwann cells studied by the previous research team. The gene’s activity was similar to the pattern seen in the liver of a still developing human fetus.

‘These little bacteria know how to feed the liver to keep it functioning,’ said Professor Rambukana. He explained that the reason leprosy germs grow in the liver may be due to the advantage of having more living space.

More importantly, understanding the mechanism by which leprosy bacteria transform normal cells into stem cells may lead to the development of drugs and treatments that can induce liver regeneration in people with liver disease.

All of these ideas remain untested. Professor Darius Widera of the University of Reading in the UK, who reviewed the paper, told the BBC: ‘It could pave the way for a new therapeutic approach to treat liver diseases such as cirrhosis, but it is unclear whether it can be applied to humans since the results were made in animal models.” . Furthermore, it was emphasized that a more careful clinical trial is needed as leprosy has the risk of causing disease.

Udayan Apt, a biologist at the University of Kansas Medical Center in the US, told Science that ‘leprosy bacteria have figured out how to trick liver cells into providing shelter, but it’s amazing how they can divide cells without killing them. “. While these questions remain unanswered, he said, “the discovery that there is a way to simultaneously divide and regenerate while maintaining liver function is quite exciting.”

The document can be found at the following link (https://www.cell.com/cell-reports-medicine/fulltext/S2666-3791(22)00379-2?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com %2Fretrieve% 2Fpii%2FS2666379122003792%3Fshowall%3Dtrue).