New insights on chitinases immunologic activities

Mammalian chitinases and the related chilectins （ChiLs） belong to the GH18 family, which hydrolyse the glycosidic bond of chitin by a substrate-assisted mechanism. Chitin the fundamental component in the coating of numerous living species is the most abundant natural biopolymer. Mounting evidence suggest that the function of the majority of the mammalian chitinases is not exclusive to catalyze the hydrolysis of chitin producing pathogens, but include crucial role specifc in the immunologic activities. The chitinases and chitinase-like proteins are expressed in response to different proinflammatory cues in various tissues by activated macrophages, neutrophils and in different monocyte-derived cell lines. The mechanism and molecular interaction of chitinases in relation to immune regulation embrace bacterial infection, infammation, dismetabolic and degenerative disease. The aim of this review is to update the reader with regard to the role of chitinases proposed in the recent innate and adaptive immunity literature. The deep scrutiny of this family of enzymes could be a useful base for further studies addressed to the development of potential procedure directing these molecules as diagnostic and prognostic markers for numerous immune and infammatory diseases.

Comparison of YKL-39 and CHIT-1 expression during macrophages differentiation and polarization

The chitinase-like proteins YKL-39 (chitinase 3-like-2) and Chitortriosidase (CHIT-1) are members of the chitinases family. YKL-39 expression has been associated with osteoarthritis, whereas CHIT-1 activity is regarded as a biochemical marker of macrophage activation. So far, the physiological or pathological role of YKL-39 in the inflammation is still poorly understood. We compared YKL-39 and CHIT-1 modulation during monocyte to macrophage transition and polarization. Gene expression analysis was investigated by real-time PCR from mRNA of human monocytes obtained from buffy coat of healthy volunteers, from mRNA of polarized macrophages to classically activated macrophages (or M1), obtained by interferon-γ and lipopolysaccharide exposure, and from mRNA of alternatively activated macrophages (or M2) obtained by interleukin-4 exposure. We demonstrated different variations of YKL-39 and CHIT-1 production during macrophages polarization. CHIT-1 levels gradually increase in the course of the time with a peak of expression between the fifth and the seventh day of culture. In contrast, YKL-39 expression was unaltered in the diverse stage of HMMs differentiation, but increased significantly in M1 polarized macrophages and reverted to base levels in M2 polarized macrophages. These findings indicated that the function of YKL-39 is much more restricted and selective than that exerted by CHIT-1.