C-Type Lectin Receptor DCAR Recognizes Mycobacterial Phosphatidyl-Inositol Mannosides to Promote a Th1 Response...

Area of Science:

• Immunology
• Microbiology
• Glycobiology

Background:

• Phosphatidyl-inositol mannosides (PIM) are unique mycobacterial glycolipids involved in immune stimulation and pathogenicity.
• The role of specific receptors in mediating PIM-induced immune responses remains incompletely understood.

Purpose of the Study:

• To identify the direct receptor for PIMs on host immune cells.
• To elucidate the function of this receptor in the context of mycobacterial infection and immune response.

Main Methods:

• Reporter cell assays to assess DCAR activation by mycobacteria and PIMs.
• Purification and characterization of PIM ligands from mycobacteria.
• Analysis of DCAR expression in immune cells.
• In vivo studies using Clec4b1-deficient mice to evaluate immune responses and bacterial load.

Main Results:

• Dendritic cell immunoactivating receptor (DCAR) was identified as a direct receptor for acylated PIMs from mycobacteria.
• DCAR expression was observed in peritoneal macrophages and inflammatory cells in the lungs and spleen.
• PIM-induced production of monocyte chemoattractant protein-1 (MCP-1) was dependent on DCAR and FcRγ.
• Clec4b1-deficient mice exhibited impaired T-cell IFNγ production, reduced inflammatory cell recruitment, and increased mycobacterial load.

Conclusions:

• DCAR is a critical receptor for mycobacterial PIMs.
• DCAR signaling promotes the recruitment of inflammatory cells and enhances T-cell responses against mycobacteria.
• Targeting the DCAR-PIM interaction may offer a therapeutic strategy for mycobacterial infections.