Saturday, October 8, 2011

Parasite worm can be treated by letting it kill itself

Parasitic fluke worms that cause the deadly disease schistosomiasis can be treated by making the worm kill its own cells. Scientists discovered a complex cell death program in these worms, which are dubbed schistosomes. This mechanism relies on a balance with molecules that promote cell death, and molecules that help the cells survive. With a little help, the balance could be tipped towards cell death, which could serve as a novel therapy for the disease that kills 200.000 people each year, and has already infected over 200 million people.

The cell death mechanism is similar to apoptosis, a process that is found in many animals, including humans. In apoptosis, cells are instructed to kill themselves, whereafter a complex signaling pathway is initiated. This 'death sequence' culminates in shutting down the cell completely, with all the cellular machinery wrapped into little packages, that can be taken up by other cells. By killing a cell in a controlled fashion, no cellular debris lingers around after the apoptosis process is completed. According to the scientists that discovered the apoptosis-like process in schistosomes, not only is the process similar, but the key cell death molecule in these worms has a structure that is almost identical to the one in humans. Due to the similarities, we know a lot about the characteristics of this molecule, and we can use this information to design new drugs to specifically target the death pathway in these worms.

In humans, apoptosis is an important process to regulate cell count in tissues and organs. Old and damaged cells can be instructed to kill themselves, to make way for fresh cells that take over their function. It is also a safety mechanism to prevent uncontrolled cell growth, which can cause cancer. During development, the apoptosis process is used to eliminate tissue between your fingers. This gives us our long, lean fingers that we can use for complex tasks, like typing this blogpost.

Schistosomiasis is a disease that causes internal organ damages, and can eventually cause death. It is the second most prevalent parasitic disease, after malaria, and there are few drugs available to fight the worm infection underlying the disease. It is often called 'snail fever', because fresh water snails are able to transmit the disease, if they carry the parasite. 

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