Gamma-Irradiated Bifidobacteria Establish a Protective Effect on Mice to Experimental Radiation Exposure

Abstract

The purpose of this work is to assess the radioprotective effect exerted by the irradiated form of Bifidobacterium bifidum probiotic on experimentally irradiated mice. As a result of the research, we were able to determine experimentally the optimal dose of gamma rays (12–14 Gy) that ensures a switching of the metabolism of probiotic microorganisms towards the synthesis of superoxide dismutase (an antiradical enzyme) and activates production of interferon (a mediator of immunopoiesis) by immunocompetent cells. The mice were exposed to 8.0 Gy doses of $$ {}_{\;}{}^{137}\mathrm{Cs} $$ gamma radiation at an exposure dose rate of 3.13 × 10−5 C/(kg s). Twenty four hours after the exposure, the animals were administered subcutaneously a single 0.2-ml dose (1 × 108 CFU) of either native bifidumbacterin or the radiation-modified form of this probiotic. The radioprotective effect was evaluated according to various parameters, such as the change in hematological parameters, the quantitative composition of the gut microbiome, and the ability of the drug to induce the release intercellular interaction mediators (interferons) by stimulated immune cells of the host. A single subcutaneous injection of 1 × 108 CFU of either native bifidumbacterin or its irradiated form, administered in the composition of the growth medium 24 h after the irradiation, protects 60 to 80% of lethally irradiated white mice. The radioprotective effect of the biopreparation is associated with a milder form of acute radiation syndrome, makes pancytopenia less severe (1.13–1.21 times against 2.7–4.9 times in the irradiated control group), and reduces the number of opportunistic enterobacteria (2.2 lg against 4.9 lg in the irradiated animals) in the intestine.