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Updated: May 16, 2026
Macrophage Differentiation and Polarization into an M2-Like Phenotype using a Human Monocyte-Like THP-1 Leukemia Cell Line
Published on: August 2, 2021
Modulation of chitotriosidase during macrophage differentiation
Michelino Di Rosa1, Giulia Malaguarnera, Corinne De Gregorio
1Department of Bio-medical Sciences, University of Catania, Via Androne, 83, 95124, Catania, Italy.
Abstract:
Macrophages as a principal component of immune system play an important role in the initiation, modulation, and final activation of the immune response against pathogens. Upon stimulation with different cytokines, macrophages can undergo classical or alternative activation to become M1 or M2 macrophages, which have different functions during infections. Although chitotriosidase is widely accepted as a marker of activated macrophages and is thought to participate in innate immunity, particularly in defense mechanisms against chitin containing pathogens, little is known about its expression during macrophages full maturation and polarization. In this study we analyzed CHIT-1 modulation during monocyte-to-macrophage maturation and during their polarization. The levels of CHIT-1 expression was investigated in human monocytes obtained from buffy coat of healthy volunteers, polarized to classically activated macrophages (or M1), whose prototypical activating stimuli are interferon-γ and lipopolysaccharide, and alternatively activated macrophages (or M2) obtained by interleukin-4 exposure by real-time PCR and by Western blot analysis. During monocyte-macrophage differentiation both protein synthesis and mRNA analysis showed that CHIT-1 rises significantly and is modulated in M1 and M2 macrophages.Our results demonstrated that variations of CHIT-1 production are strikingly associated with macrophages polarization, indicating a different rule of this enzyme in the specialized macrophages.
Insights
Chitotriosidase (CHIT-1) expression significantly increases during macrophage maturation and polarization. This enzyme plays a distinct role in both M1 and M2 activated macrophages, highlighting its importance in immune responses.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Macrophages are key immune cells involved in pathogen defense and immune response modulation.
- Macrophages differentiate into M1 (classically activated) and M2 (alternatively activated) subtypes with distinct functions.
- Chitotriosidase (CHIT-1) is a known marker of activated macrophages, implicated in innate immunity against chitin-containing pathogens.
Purpose of the Study:
- To investigate the modulation of chitotriosidase (CHIT-1) expression during human monocyte-to-macrophage differentiation.
- To analyze CHIT-1 expression patterns in classically activated (M1) and alternatively activated (M2) macrophages.
- To understand the role of CHIT-1 in macrophage polarization and specialized immune functions.
Main Methods:
- Human monocytes were isolated from healthy volunteer buffy coats.
- Monocytes were differentiated into macrophages and polarized into M1 (using interferon-γ and lipopolysaccharide) or M2 (using interleukin-4) phenotypes.
- CHIT-1 expression was quantified using real-time PCR for mRNA analysis and Western blot for protein analysis.
Main Results:
- CHIT-1 expression, at both the mRNA and protein levels, significantly increased during monocyte-to-macrophage differentiation.
- CHIT-1 levels were modulated differently in M1 and M2 polarized macrophages.
- Variations in CHIT-1 production were strongly associated with macrophage polarization states.
Conclusions:
- Chitotriosidase (CHIT-1) expression is significantly upregulated during macrophage maturation.
- CHIT-1 production is differentially regulated in M1 and M2 macrophages, suggesting distinct roles in specialized immune functions.
- These findings indicate that CHIT-1 plays a specialized role in macrophages depending on their activation state.
