Modulation of chitotriosidase during macrophage differentiation.

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.