DCIR and its ligand asialo-biantennary N-glycan regulate DC function and osteoclastogenesis

Area of Science:

• Immunology
• Glycobiology
• Bone Biology

Background:

• Dendritic cell immunoreceptor (DCIR) is a C-type lectin receptor implicated in immune regulation.
• Previous studies demonstrated that Dcir-/- mice exhibit autoimmune conditions and metabolic bone abnormalities.
• The specific ligands and functional mechanisms of DCIR remained largely unknown.

Purpose of the Study:

• To identify the ligands for DCIR.
• To elucidate the role of DCIR in autoimmune diseases and bone metabolism.
• To investigate the impact of N-glycan sialylation on DCIR function.

Main Methods:

• Expression analysis of DCIR on osteoclasts and dendritic cells (DCs).
• Binding assays to identify DCIR ligands, specifically asialo-biantennary N-glycans (NA2).
• In vitro studies using Dcir-/- cells to assess osteoclastogenesis and DC function.
• In vivo studies involving neuraminidase treatment in mouse models of autoimmune diseases.

Main Results:

• DCIR was found to bind to asialo-biantennary N-glycans (NA2) on bone and myeloid cells.
• NA2 inhibited osteoclastogenesis, while its absence (in Dcir-/- cells) enhanced it.
• Neuraminidase treatment, exposing NA2, suppressed osteoclastogenesis and DC function.
• Neuraminidase treatment ameliorated autoimmune disease models (collagen-induced arthritis and experimental autoimmune encephalomyelitis) in a DCIR-dependent manner.

Conclusions:

• DCIR's activity is modulated by the terminal sialylation of biantennary N-glycans.
• The DCIR-NA2 interaction plays a critical role in regulating autoimmune responses and bone metabolic diseases.
• Targeting DCIR-glycan interactions may offer therapeutic strategies for these conditions.