In vitro investigation of m2 macrophage differentiation and phagocytic capabilities
Thai, Hy
Authors
Hy Thai
Abstract
Amyloid-related diseases are characterised by the accumulation of extracellular β-amyloid 42 (Aβ42) plaques on specific tissues. Macrophages, a key immune system component, exhibit high plasticity and can polarise across an M1 and M2 spectrum. M2 macrophages, essential for tissue repair and debris clearance, have shown potential in degrading and clearing Aβ42 plaques, offering a novel therapeutic approach. However, the presence of serum amyloid P, which binds to Aβ42 plaques, may hinder this clearance.
This study aimed to generate in vitro human M2 macrophages from immortalised human monocytes, THP-1 and Mono Mac 6, to investigate their interaction with synthetic Aβ42. This focused on characterising molecules binding to Aβ42 and assessing cytokine expressions to evaluate their potential in amyloid clearance.
Monocytes were differentiated into M2 macrophages using Phorbol myristate acetate (PMA), then polarised with IL-4 and Macrophage colony-stimulating factors (M-CSF) for varying durations. Surface markers, cytokine production, and phagocytic activity toward microbeads and synthetic Aβ42 were evaluated using flow cytometry, ELISA, fluorescence and confocal microscopy. Results indicated that PMA-primed macrophages successfully polarised into the M2 phenotype, with optimal polarisation achieved after 48 hours of IL-4/M-CSF treatment. These M2 macrophages exhibited robust phagocytic activity, particularly toward Phosphatidylserine microbeads and Aβ42 fibrils and oligomers, while maintaining an anti-inflammatory profile with low TNF-α production. This suggested that M2 macrophages effectively cleared amyloid deposits while limiting inflammation. Future work will explore how serum amyloid P (SAP) affects M2 macrophage clearance of Aβ42 plaques and strategies to improve their function. The interaction between M2 macrophages and biofilms will also be studied. The use of EB1089 to reactivate M2 macrophages in chronic inflammation and ageing will be investigated. The efforts to engineer and enhance M2 macrophages for targeted amyloid clearance will be explored to develop new therapies for amyloid-related diseases.
