Secretion characteristics of cytokines in mice after infected with Nocardia cyriaciorgica GUH-2

ObjectiveTo understand the characteristics of cytokine secretion in mice after infected with Nocardia cyriacigeorgica, clarify its pathogenesis, and provide theoretical basis for the treatment of nocardiosis.

MethodsBALB/c mice were infected by nasal drip, and then the bacterial loads in the lung of the mice at different time intervals were counted by plate counting. Enzyme linked immunosorbent assay (ELISA) was used to detect the concentration of cytokines in lung tissues and serum of the mice at different time intervals. Software SPSS 23.0 was used for statistical analysis.

ResultsMost of N. cyriacigeorgica (98.35%) in the lung tissues of the mice were eliminated at 48 h after infection, and no N. cyriacigeorgica was detected in serum of the mice. In the early stage of infection, the concentrations of IL-2, IL-4, IL-6, IL-10, IL-12, TNF-α and IFN-γ in the lung tissues of the mice were significantly higher than those in the control group (P<0.01). The concentrations of these cytokines showed a trend of decline over time. In serum of the mice, the concentrations of IL-6 (6–24 h), IFN-γ (12–24 h) and IL-10 (48 h) were higher than those in the control group. The difference was significant (P<0.01). And the concentrations of IL-12 (12–48 h) and IL-4 (12 h) were significantly inhibited compared with the control group. The difference was significant (P<0.01). In addition, there were positive correlations between the concentrations of cytokines and bacterial loads in the lung tissues of the mice.

ConclusionIn the process of infection with N. cyriacigeorgica in mice, cytokines such as IL-6, TNF-α, IL-12, IL-2, IFN-γ, IL-10, IL-4 were secreted, especially the high concentrations of IL-6, IL-12, IFN-γ and IL-10. The interactions of various cytokines were involved in the immune response mechanism of eliminating N. cyriacigeorgica infection.