Under their shells, armadillos hide a secret: when exposed to the bacterium that causes leprosy in humans, their livers expand considerably. This oddity, which was discovered in a recent study, might offer insights into how the body regulates liver regeneration and how to speed up the process in humans.

Hepatologist Alejandro Soto-Gutiérrez of the University of Pittsburgh School of Medicine, who was not involved in the study, calls the discovery quite cool. He points out that since mice and rats make up the majority of animal research on liver regeneration, it is “refreshing” that researchers are studying a different species that might offer fresh perspectives.

The liver is the body’s master of regeneration, having the capacity to recover from illnesses and traumas. When a kidney is donated, a replacement does not grow in its place. However, the remaining portion of a donor’s liver will grow back into a full-sized organ even if two thirds of it are removed for transplantation. Scientists are unsure how to start this rejuvenation in people whose livers are deteriorating due to cirrhosis or other diseases, though.

Almost 10 years ago, regeneration biologist Anura Rambukkana of the University of Edinburgh and colleagues discovered leprosy-causing bacteria infect cells known as Schwann cells that embrace neurons. Once the bacteria have established themselves in their new environment, they encourage the cells to revert to a more immature developmental state and resemble stem cells.

However, those tests were done on mouse cells in a dish. Would the same procedure take place in a real animal?

Because leprosy bacteria do not thrive in mice or other common lab animals, Rambukkana claims that this question kept him up at night. Then he remembered that the study’s germs originated from a laboratory in Louisiana where scientists were raising them in nine-banded armadillos, which are an ideal host for the bacterium.

Rambukkana phoned a scientist at the facility to inquire whether he had observed anything strange about the organs of sick armadillos because the germs thrive in the animals’ livers. The researchers constantly see that the liver is enlarged.

The new research supports that finding. Rambukkana and colleagues report today in Cell Reports Medicine that the livers of armadillos afflicted with leprosy bacteria are roughly one-third larger than those of their uninfected counterparts. Furthermore, the liver does not just swell uncontrollably in animals. The larger organs preserve their distinctive structure, including the precise number of lobes and the unusual honeycomb-like arrangement of subunits. Researchers may be able to comprehend the mechanics of regeneration in the human liver by studying how the livers of animals continue to grow.

Patients with infections or other liver diseases may develop tumors and collect scar tissue, which can impair the function of the organ. The armadillos, however, showed no indication of either issue, according to the researchers. Furthermore, their examination of a number of liver proteins revealed that the organs were functioning appropriately.

Rambukkana and colleagues assessed gene activity in infected and uninfected rats to elucidate how the liver bulks up. The liver cells in armadillos that contained the bacteria changed to resemble stem cells, just like the Schwann cells in their earlier research. The pattern of gene activity in the liver of an infected animal matched that of the liver of a developing human.

According to Rambukkana, these small microorganisms know how to build a working liver. He also said that a larger liver is probably helpful for the microorganisms since it offers more living area. Scientists might be able to use this process to help liver disease sufferers regenerate their organs.

However, according to George Michalopoulos, a liver regeneration researcher also at the Pitt School of Medicine, the study leaves a lot of uncertainties. For example, he claims that the researchers must demonstrate that the liver infected armadillos is not simply enlarged because it becomes filled with bacteria.

Researchers will also need to find a solution to another problem before this anatomical abnormality can be used to create viable treatments. According to liver researcher Udayan Apte of the University of Kansas Medical Center, the bacteria have found out how to trick the liver cells into giving them refuge. He also asked h ow can the bacteria prevent the cells from dying and instead cause them to divide?

Apte claims that despite these difficulties, he is enthusiastic about the approach’s potential. The study demonstrates that”the liver can remain functioning, divide, and regenerate at the same time.

Sources:

https://www.science.org/content/article/leprosy-spurs-growth-armadillo-livers-offering-clues-organ-regeneration

https://www.cell.com/cell-reports-medicine/fulltext/S2666-3791(22)00379-2