Plasmacytoid dendritic cells and C1q differentially regulate inflammatory gene induction by lupus immune complexes

Area of Science:

• Immunology
• Molecular Biology
• Systemic Lupus Erythematosus (SLE) research

Background:

• Immune complexes (ICs) are central to systemic lupus erythematosus (SLE) pathogenesis.
• The specific blood cells and gene programs activated by lupus ICs remain incompletely understood.

Purpose of the Study:

• To identify dominant blood cell types and inflammation-related gene programs stimulated by lupus ICs.
• To investigate the role of C1q in modulating IC-induced cellular responses.

Main Methods:

• Exposure of human peripheral blood mononuclear cells (PBMCs) and isolated CD14(+) monocytes to SLE ICs with or without C1q.
• Microarray analysis to assess gene expression changes.
• Analysis of specific monocyte subpopulations (CD14(dim)).

Main Results:

• SLE ICs activate both type I interferon-dependent and -independent gene programs.
• C1q-containing ICs significantly reduced the expression of many interferon-response genes.
• CD14(dim) monocytes showed greater responsiveness to ICs compared to bulk CD14(+) monocytes or other subsets.

Conclusions:

• Plasmacytoid dendritic cells and CD14(dim) monocytes are critical regulators of IC-driven inflammation in SLE.
• C1q plays a crucial role in modulating the inflammatory response to ICs.
• Identified key pathways involved in IC-mediated inflammation offer therapeutic targets.