Leprosy bug turns adult cells into stem cells

Leprosy bacteria, Mycobacterium lepraecan reprogram cells to first revert to a stem-cell-like state and then to mature into completely different cell types.  This is a new finding by Takeshi Masaki and associates in Cell 152, 51–67 (2013). The team was researching the mechanism by which leprosy spreads around the body when they made this discovery. The exact mechanism by which the bacterium carries out the hijacking has not yet been elucidated but, once unravelled, it has the potential to become a major therapeutic strategy against the disease.

It appears that the prime targets of Mycobacterium leprae are Schwann cells, which are part of the peripheral nervous system. The bacterial cells wrap around the nerve cells and prevent the electric signals from passing through.  This causes the characteristic loss of tactile sensation in peripheral parts of the body.

Further investigation revealed that the bacterium changed mature Schwann cells into a stem-like state by turning off genes associated with maturity and turning on embryonic or developmental ones. The reprogrammed stem cells are able to migrate to different body areas, carrying the bacteria with them. Whatever the destination, the infected cells integrate with that tissue’s cells and spread the bacteria.

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