HMGN1 and R848 Synergistically Activate Dendritic Cells Using Multiple Signaling Pathways

Area of Science:

• Immunology
• Cancer Research
• Molecular Biology

Background:

• High mobility group nucleosome-binding protein 1 (HMGN1) is a Th1-polarizing alarmin insufficient for antitumor immunity alone.
• Previous studies indicated a synergistic effect between HMGN1 and R848 (a TLR7/8 agonist) in activating dendritic cells (DCs) and inducing antitumor immunity.
• The precise mechanisms underlying the synergistic DC activation by HMGN1 and R848 remained unclear.

Purpose of the Study:

• To elucidate the synergistic mechanisms by which HMGN1 and R848 activate dendritic cells (DCs).
• To investigate the impact of HMGN1 and R848 co-stimulation on DC maturation, cytokine production, and intracellular signaling pathways.
• To assess the potential of this combination for promoting Th1 immune responses and antitumor immunity.

Main Methods:

• Co-stimulation of human monocyte-derived DCs (MoDCs) and mouse bone marrow-derived DCs (BMDCs) with HMGN1 and R848.
• Analysis of DC surface marker expression (CD80, CD83, CD86, HLA-DR) and cytokine production (IL-12p70, IL-1β, TNF-α).
• Investigation of intracellular signaling pathways including NF-κB, MAPKs, and interferon regulatory transcription factors (IRFs).
• RNA-sequencing (RNA-seq) analysis of gene expression in MoDCs.

Main Results:

• Co-stimulation markedly upregulated DC surface markers and synergistically enhanced pro-inflammatory cytokine production.
• The combination synergistically activated NF-κB, MAPKs, and promoted nuclear translocation of IRF3 and IRF7, leading to increased type 1 IFN expression.
• RNA-seq revealed synergistic upregulation of genes involved in DC maturation and Th1 polarization (e.g., IL12A, IL12B, IFNB1).
• Similar signaling pathways were observed in both human and mouse DCs.

Conclusions:

• HMGN1 synergizes with R848 to activate human and mouse DCs through multiple intracellular signaling events.
• The synergistic activation culminates in the activation of key transcriptional factors, promoting Th1 immune responses.
• This combination holds significant implications for clinical trials, demonstrating potential for inducing optimal Th1 immunity and tumor rejection.