Hydro Peroxide leads the way to the immune system

When you were young, you used to put it on the scratch on your finger so you wouldn't get infected. When you grow up, you use it to bleach your hair. Now scientists have found yet another function for the colorless liquid to be purchased everywhere without this doctor's prescription: your body may be using hydrogen peroxide as an envoy to send troops. Cells to reinforce the injured tissue.

Using zabrafish as a subject to experiment, the researchers included Timothy Mitchison, professor of systems biology at Harvard Pharmacy and Thomas Look, a professor at Dana Farber Cancer Institute. discovered that when the caudal fin of these organisms was injured, an amount of hydrogen peroxide (also known as old oxygen) was released from the wound and spread to surrounding tissues. The rescue white blood cell groups will respond to signals from these chemical messengers by crawling to the lesion area and starting their work.

'Previously we knew that when the body was injured, the white blood cells would perform the task, and you would have to admit it was really a spectacular biological phenomenon knowing that these cells emitted The wound appeared almost immediately, ' Mitchison said. 'But we still do not know exactly where the actions of these cells are in response to information. We already know what pulls white blood cells to a chronic infection, however, in the case of an isolated mechanical injury, we still don't know where the signal is transmitted to white blood cells. . "

These findings were published in the June 4 issue of Nature.

Philipp Niethammer, Ph.D., works with the lab with Mitchison, and Clemmens Grabber, colleague of Look, started this research project while not caring about the healing process. In contrast, they only studied molecular groups named reactive oxygen species (ROS). These tiny oxygen-based molecules, including hydrogen peroxide, can be very helpful, but can also be harmful. Niethammer and Grabber simply want to find out how to detect ROS molecules in a living organism.

To do this, they introduced a gene that could change color when hydrogen peroxide is present in zabrafish fish embryos. After a few days, when the fish embryo enters the larval stage, this artificial gene has spread throughout the body, reaching the deepest corners and any presence of hydrogen peroxide will be red.

So how does the fish produce a reactive chemical like hydrogen peroxide?

In the zabrafish fish tail, there is a small wound in the fins.Red indicates a high concentration of hydrogen peroxide, blue indicates a low hydrogen peroxide area.This amount goes beyond one cell and spreads to the surrounding tissue.(Photo: Philipp Niethammer)

It has long been thought that white blood cells produce hydrogen peroxide. A very easy way for this chemical to be produced is to cause a small wound on the fish, then use this observation microscope when the white blood cells gather around the wound. But what surprised the scientists was that they immediately saw hydrogen peroxide appear at the site of the wound, before the first white blood cells were present , and quickly spread to surrounding tissues.

The team repeated the experiment, this time removing the protein they thought produced hydrogen peroxide in the thyroid gland in humans. As a result, not only does hydrogen peroxide not appear at the wound, but white blood cells also do not react to the wound.

'This is really a big discovery for us,' said Niethammer. 'We are not too surprised that this measure can prevent hydrogen peroxide from being born, but we did not expect that white blood cells did not respond. This indicates that white blood cells need hydrogen peroxide to get information and move for the wound.

Of course, zebrafish fish are not human, and while our genomes have many similarities with this small fish, it is not certain that natural selection has preserved this process in evolution. . Anyway, these findings still have some idea in studying the mechanism of active hydrogen peroxide in the human body.

In the human body, hydrogen peroxide is basically produced in three places: lungs, intestines, and thyroid gland. Because hydrogen peroxide and other proteins responsible for producing other ROS molecules, particularly present in the lungs and intestines, the researchers hypothesize that human diseases associated with these findings will These include diseases of the lungs and intestines related to the number of inappropriate white blood cells, such as asthma, chronic obstructive pulmonary disease, and some inflammatory bowel diseases.

Mitchison said: 'It is very logical that tissues in both the lungs and intestines always produce hydrogen peroxide. In cases such as asthma, the pulmonary epithelium produces too much hydrogen peroxide because of chronic lung damage. Applying our findings in zebrafish fish on the human body, it can be seen that this is the reason why the white blood cell count is always unreasonable. This is really a matter of concern. '

Mitchison is currently working on preparations for this hypothesis.

The research was funded by the National Institutes of Health.

Refer:
Philipp Niethammer, Clemens Grabher, A. Thomas Look, Timothy J. Mitchison. A tissue-scale gradient of hydrogen peroxide mediates rapid wound detection in zebrafish. Nature, 2009; 459 (7247) DOI: 10.1038 / nature08119