Antibacterial and Immunomodulating Activity of Silver Nanoparticles on Mice Experimental Tuberculosis Model

The antibacterial activity of silver nanoparticles with a size of 43.6 ± 10.7 nm against strain Mycobacterium tuberculosis H37Rv was studied in vitro (the studied concentrations of silver nanoparticles were 0.1; 1; 10; 25, and 50 μg/mL) and in an experimental murine model of chronic tuberculosis. It was shown that silver nanoparticles at a concentration of 50 μg/mL suppress mycobacterial growth in vitro by 2 times. The administration of silver nanoparticles via inhalation at a dose of 0.1 mg/kg to tuberculosis-infected mice resulted in a twofold decrease in the colonization of the lungs and spleens by M. tuberculosis. In these animals, the quantity of protein in the broncho-pulmonary lavage fluid was reduced by two times, to 1908.5 ± 105.7 (P < 0.001), which indicates a decrease in the inflammatory processes in the lungs. The level of the production of reactive oxygen species by neutrophils increased, reflecting their bactericidal potential, which was reduced by 2.7 times before treatment as compared to the control group of animals (P < 0.001). After the introduction of silver nanoparticles, a recovery in the ratio of lymphocyte populations in the spleen and cytokine balance was observed. It was expressed by a decrease in the levels of IFN-γ, TNF-α, and IL-4 in the blood serum and broncho-pulmonary lavage fluid in TB mice. Thus, it was shown for the first time that the inhalation of silver nanoparticles stabilized with polyvinylpyrrolidone led not only to a noticeable bactericidal effect but also recovered the balance of the immune system of mice.