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Updated: Aug 28, 2025
Stimulation of Cytoplasmic DNA Sensing Pathways In Vitro and In Vivo
Published on: September 18, 2014
Mitochondrial DNA mediates immunoparalysis of dendritic cells in sepsis via STING signalling
1Department of Anesthesiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Background:
Mitochondrial DNA (mtDNA) is a potent activator for pro-inflammatory response. Dendritic cells (DCs) are immunosuppressed in sepsis, whether mtDNA mediates immunoparalysis in sepsis remains unknown.
Methods:
The mRNAs were assessed by qPCR. Flow cytometry was used to measure the expression of costimulatory molecules and the proliferation of CD4+ T cells. Western blot and immunofluorescence staining were used to analyse the expression of proteins. Cytokine secretion was detected by ELISA. Histology of lung tissue was used to assess the inflammatory injury.
Results:
Lipopolysaccharide-induced endotoxemia increased plasma mtDNA levels and immunoparalysis of spleen DCs, while hydrolysing mtDNA reversed immunoparalysis of spleen DCs in vivo. Moreover, cytoplasmic mtDNA of DCs was accumulated in endotoxemia and sepsis. mtDNA transfection into bone marrow-derived DCs (BMDCs) inhibited the expression of costimulatory molecules (e.g., CD40, CD80 and CD86) and the release of IL-12p70, while increasing the secretion of IL-10. Cytoplasmic mtDNA also inhibited the ability of BMDCs to promote the proliferation of CD4+ T cells. Mechanistic analysis revealed that STING signalling was required for mtDNA-mediated immunoparalysis of DCs in vivo and in vitro. Further studies showed deletion of STING reversed mtDNA-mediated immunoparalysis of DCs and improved the prognosis of endotoxemia and sepsis.
Conclusion:
Our results demonstrated that mtDNA promotes immunoparalysis of DCs, and contributes to sepsis-associated immunosuppression by activating STING signalling. Our study may provide new insights to elucidate the molecular pathogenesis of immunosuppressive DCs in sepsis.
Insights
Mitochondrial DNA (mtDNA) drives immune suppression in sepsis by paralyzing dendritic cells (DCs) via STING signaling. Clearing mtDNA restores DC function and improves sepsis outcomes.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Mitochondrial DNA (mtDNA) activates inflammatory responses.
- Dendritic cells (DCs) are crucial immune cells that become immunosuppressed during sepsis.
- The role of mtDNA in sepsis-induced DC immunoparalysis was previously unknown.
Purpose of the Study:
- To investigate whether mitochondrial DNA (mtDNA) mediates the immunoparalysis of dendritic cells (DCs) in sepsis.
- To elucidate the underlying molecular mechanisms, particularly the involvement of STING signaling.
- To explore the therapeutic potential of targeting mtDNA in sepsis.
Main Methods:
- Assessed mRNA expression using qPCR.
- Measured costimulatory molecule expression and T cell proliferation via flow cytometry.
- Analyzed protein expression using Western blot and immunofluorescence.
- Detected cytokine secretion by ELISA.
- Evaluated lung tissue for inflammatory injury via histology.
Main Results:
- Elevated plasma mtDNA levels and DC immunoparalysis were observed in endotoxemia, reversed by mtDNA hydrolysis.
- Cytoplasmic mtDNA accumulated in DCs during endotoxemia and sepsis.
- mtDNA transfection into DCs inhibited costimulatory molecules and IL-12p70, while increasing IL-10, and impaired T cell proliferation.
- STING signaling was essential for mtDNA-induced DC immunoparalysis in vitro and in vivo.
- STING deletion reversed DC immunoparalysis and improved sepsis prognosis.
Conclusions:
- Mitochondrial DNA (mtDNA) promotes dendritic cell (DC) immunoparalysis in sepsis by activating STING signaling.
- This study provides novel insights into the molecular pathogenesis of immunosuppressive DCs in sepsis.
- Targeting mtDNA and STING signaling may offer therapeutic strategies for sepsis-associated immunosuppression.
