Swertianolin regulates immunosuppression of myeloid suppressor cells in septic mice by inhibiting NF-κB and P38 signaling

Abstract

Background

Swertianolin is one of the main components of Gentianaceae Swertia plants, a traditional Chinese medicine used for the treatment of infection, fever, viral hepatitis, and pneumonia. An expansion of myeloid-derived suppressor cells (MDSCs) contributes to sepsis induced immunosuppression. We investigated the mechanism by which Swertianolin regulates MDSCs in a mouse model of sepsis.

Methods

Severe sepsis was induced in mice using caecal ligation and puncture. These mice received an intraperitoneal injection of Swertianolin. MDSCs were isolated and analyzed by flow cytometry; serum concentrations of immunosuppressive factors were detected by ELISA; and mitogen-activated protein kinase and nuclear factor-κB (NFκB) were detected by Western blots.

Results

We found that Swertianolin reduced the number of MDSCs in the marrow and the spleen while increased the number of CD4+ T cells in the spleen of mice with sepsis in comparison to controls (p < 0.05). Swertianolin reduced lung damage and improved the survival rate in mice with secondary infection of Legionella pneumophila (p < 0.05). Swertianolin inhibited the phosphorylation of p38 and nuclear translocation of p65 in MDSCs (p < 0.05), leading to decreased production of IL-10 and nitric oxide (both p < 0.05).

Conclusion

Swertianolin may improve immunosuppressive function of MDSCs and increased T cell activity by inhibiting p38 phosphorylation and NF-κB activation.