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Proteins increase resistance to lethal doses of radioactive radiation
Last reviewed: 01.07.2025
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Proteins that prevent blood clotting increase the body's resistance to lethal doses of radioactive radiation.
Last year's incident at the Fukushima nuclear power plant has once again forced us to address the problem of protection from radiation. It is believed that high doses of radiation act on the body quickly and irreversibly, damaging primarily the bone marrow and intestines. As a result, the number of blood cells drops sharply, as a consequence - the immune system stops working and the body becomes easy prey even for the weakest pathogens. The main means of assistance in this case is granulocyte-macrophage colony-stimulating factor, a protein that stimulates the formation of new blood cells. But, firstly, it is very demanding in storage, secondly, it must be administered as soon as possible after irradiation, and thirdly, its use is sometimes accompanied by side effects.
Last fall, scientists from Harvard (USA) managed to find a remedy (a mixture of an immune bactericidal protein and an antibiotic) that stabilized the condition of irradiated animals and increased survival even after exceptionally high doses of radiation. Their colleagues from the University of Cincinnati and the Wisconsin Blood Research Institute (both in the US) reported in the journal Nature Medicine about a mixture of proteins with a similar effect: the blood protein thrombomodulin and activated protein C (xigris) increased the survival of irradiated mice by 40–80%.
The scientists came to the discovery by studying mutant mice that were resistant to radiation. It turned out that they had increased synthesis of thrombomodulin, an anticoagulant protein that prevents excessive blood clotting. Thrombomodulin activates protein C, which also limits coagulation. They had already tried to use activated protein C as an anti-inflammatory agent, but later abandoned the idea due to the low efficiency of the commercial drug. Now, apparently, this protein will have a second chance. The scientists irradiated about fifty mice with a radiation dose of 9.5 Gy and after 24 or 48 hours, they injected some of the test subjects with activated protein C. After a month, only a third of those who were not injected with the protein survived, while an injection of protein C increased survival to 70%. Thrombomodulin had a similar effect, but for this to happen, it had to be injected within the first half hour after irradiation.
The researchers have no doubt that both proteins will be added to the arsenal of anti-radiation protection tools. In their favor is the fact that at least one of them can work even after a significant time after irradiation. At the same time, both thrombomodulin and protein C have already participated in clinical trials, that is, their interaction with the human body should not bring any surprises.
To achieve the greatest effect, it is obviously necessary to introduce both proteins, since, in addition to the external protein C, it would not hurt to activate its internal reserves with the help of thrombomodulin. However, scientists still have to work on deciphering the mechanism of their action (why are anticoagulant proteins good against radiation?)...
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