Abstract
Sepsis is a life-threatening condition caused by an immune response triggered by infection, and highly elevated cytokine/chemokine levels in the blood play crucial roles in the progression of sepsis. Serum exosomes are nanovesicles that have multiple biological functions, playing roles in antigen presentation, intercellular signal communication, inflammatory response and immune surveillance. However, the biological functions and related molecular bases remain to be elucidated. In this study, we investigated the profiles of cytokines/chemokines harbored in the exosomes of septic mice and explored the mechanisms of immunomodulation on T cells treated with exosomes harvested from septic mice. Blood cytokines/chemokines existed in both the soluble form and in the insoluble exosomal form; the profiles of the cytokines/chemokines in these two forms displayed different dynamics in the blood of mice challenged with LPS. Exosomes from septic mice induced the differentiation of Th1/Th2 cells, which was blocked by specific antibodies targeting IL-12 and IL-4. In addition, these exosomes significantly augmented the proliferation and migration of T lymphocytes. Furthermore, preadministration of exosomes by intravenous injection restrained the inflammatory response, attenuated lung and liver tissue damage, and prolonged the survival of cecal ligation and puncture (CLP) mice. Our results indicate that exosomes enriched with cytokines/chemokines play critical roles in T cell differentiation, proliferation and chemotaxis during the sepsis process and have a protective effect on cecal ligation and puncture (CLP) mice. Thus, these findings not only strengthen our understanding of the role of sepsis via exosomes but also provide potential targets for therapeutic applications.