An unexpected discovery
Intestinal bacteria protect against radiation
Anatoly Glossev, Vesti
Intestinal bacteria of some species can protect a person from the effects of radiation exposure. This discovery, among other things, can help to preserve the health of patients undergoing radiation therapy for cancer.
The details are described in a scientific article published in the journal Science (Guo et al., Multi-omics analyses of radiation survivors identify radioprotective microbes and metabolites).
Radiation damages DNA. It is especially dangerous for actively reproducing cells, such as blood and intestinal cells.
However, it also helps to save people from cancer: one of the most common methods of treating tumors is radiation therapy. The tumor is irradiated to kill cancer cells. But along with them, healthy cells also come under attack. As a result, some patients develop side effects from the hematopoietic organs and intestines. Sometimes they are very serious and even dangerous.
Doctors have been looking for medicines that could protect vulnerable organs from the effects of radiation for a long time. And now there is an unexpected breakthrough on this front.
Biologists from five US research centers irradiated mice with potentially lethal doses of radiation. To the surprise of scientists, some rodents not only survived, but also maintained a normal life expectancy. The study showed that the irradiation was carried out by those animals in whose intestines two families of bacteria were abundantly represented: Lachnospiraceae and Enterococcaceae.
Then scientists examined stool samples from 21 patients receiving radiation therapy in connection with the diagnosis of leukemia. It turned out that the more bacteria of these families a person had, the less he suffered from diarrhea (a side effect of intestinal irradiation).
Biologists conducted additional experiments on animals to find out how microorganisms can protect the body from radiation. Scientists have concluded that it's two substances created by these bacteria: propionate and tryptophan.
Then the experimenters tried to introduce these compounds into the body of mice with a normal intestinal microbiome. And this protected the rodents from the effects of radiation: these animals were found to have less DNA damage in the cells of the intestine and hematopoietic organs.
But how do these compounds protect DNA? The fact is that radiation damages the "heredity molecule" in several ways. One of them is that the particles of the radiation beam (for example, protons) directly destroy the bonds between the atoms in the molecule. But no less important is the other way. Irradiation causes the production of proinflammatory proteins and reactive oxygen species in the cell. Inflammation and oxidative stress caused by radiation damage the DNA of cells.
Note that propionate and tryptophan are registered in some countries as food additives. But this does not mean that patients receiving radiation therapy should immediately run to the pharmacy for them.
Scientists need to conduct clinical trials that will confirm that these drugs really protect the body when exposed to radiation. The authors hope to start these tests in the near future.
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