Folate receptor-β constitutes a marker for human proinflammatory monocytes

Area of Science:

• Immunology
• Cell Biology
• Rheumatology

Background:

• Activated macrophages play a key role in inflammatory and autoimmune diseases.
• Macrophages are known to overexpress Folate Receptor beta (FR-β).
• FR-targeted therapies show promise for inflammatory diseases, but expression on other cells is unclear.

Purpose of the Study:

• To investigate the expression of FR-β on various hematopoietic cells.
• To identify specific monocyte subsets expressing FR-β.
• To explore FR-β as a potential therapeutic target for autoimmune diseases.

Main Methods:

• Analysis of peripheral blood cells using a monoclonal antibody (mAb) to human FR-β.
• Molecular characterization of FR-β expressing monocytes.
• Assessment of folate-binding capacity and co-expression of inflammatory markers (CCR2, HLA-DR).
• Analysis of synovial monocytes from Rheumatoid Arthritis (RA) patients.

Main Results:

• Only monocytes, specifically the classic/pro-inflammatory subset (CD14(high)CD16(-)), express FR-β.
• FR-β positive monocytes exhibit folate-binding capabilities.
• FR-β co-expresses with pro-inflammatory markers CCR2 and HLA-DR on monocytes.
• Synovial monocytes from RA patients also express FR-β.

Conclusions:

• FR-β is uniquely expressed on the pro-inflammatory monocyte subset.
• This specific expression pattern provides a novel target for therapeutic strategies.
• Targeting FR-β may suppress the migration of inflammatory monocytes into inflamed tissues, aiding autoimmune disease treatment.