Discovering Molecules That Regulate Efferocytosis Using Primary Human Macrophages and High Content Imaging

Area of Science:

• Immunology
• Cell Biology
• Pharmacology

Background:

• Defective apoptotic cell clearance by macrophages contributes to inflammation and autoimmunity.
• Macrophages are key phagocytes responsible for non-inflammatory removal of dead cells.
• Modulating macrophage phagocytosis presents a therapeutic avenue for inflammatory conditions.

Purpose of the Study:

• To develop and validate a high-content imaging system for evaluating antibody effects on apoptotic cell uptake by human macrophages.
• To assess a panel of antibodies for their ability to modulate phagocytosis.
• To identify novel therapeutic targets for enhancing efferocytosis.

Main Methods:

• Utilized high-content imaging to quantify the Phagocytic Index (PI) of primary human macrophages.
• Screened a panel of antibodies generated against human macrophages.
• Validated findings by identifying antibodies targeting the MerTK receptor.

Main Results:

• Developed a feasible system for evaluating antibody-mediated effects on phagocytosis.
• ~50% of tested antibodies enhanced apoptotic cell uptake, while ~5% inhibited it.
• Identified two antibodies that enhance uptake by targeting MerTK, independent of known ligands Gas6 or ProS.

Conclusions:

• The developed method effectively identifies modulators of efferocytosis.
• Antibodies targeting MerTK can enhance apoptotic cell clearance, validating this pathway for therapeutic development.
• This strategy allows for the discovery of novel pathways regulating phagocytosis without requiring purified proteins.