Chitin, the second most abundant polysaccharide in nature after cellulose, consist exoskeleton of lower organisms such as fungi, crustaceans and insects except mammals. Recently, several studies evaluated immunologic effects of chitin in vivo and in vitro and revealed new aspects of chitin regulation of innate and adaptive immune responses. It has been shown that exogenous chitin activates macrophages and other innate immune cells and also modulates adaptive type 2 allergic inflammation. These studies further demonstrate that chitin stimulate macrophages by interacting with different cell surface receptors such as macrophage mannose receptor, toll-like receptor 2 (TLR-2), C-type lectin receptor Dectin-1, and leukotriene B4 recepptor (BLT1). On the other hand, a number of chitinase or chitinase-like proteins (C/CLP) are ubiquitously expressed in the airways and intestinal tracts from insects to mammals. In general, these chitinase family proteins confer protective functions to the host against exogenous chitin-containing pathogens. However, substantial body of recent studies also set light on new roles of C/CLP in the development and progression of allergic inflammation and tissue remodeling. In this review, recent findings on the role of chitin and C/CLP in allergic inflammation and tissue remodeling will be highlighted and controversial and unsolved issues in this field of studies will be discussed.
Animals ; Chitin/*immunology ; Chitinase/*immunology ; Glycoproteins/*immunology ; Humans ; Hypersensitivity/*immunology ; Inflammation/*immunology

OBJECTIVETo investigate the changes in serum YKL-40 level and humoral immune function and their significance in children with recurrent pneumonia.

METHODSBlood samples were collected from 30 children with recurrent pneumonia (recurrent pneumonia group), 30 children with acute pneumonia (acute pneumonia group), and 30 healthy children (control group). Serum YKL-40 levels were measured by enzyme-linked immunosorbent assay. The correlation between serum YKL-40 level and laboratory indices related to humoral immune function was analyzed. The receiver operating characteristic (ROC) curve was used to analyze the diagnostic value of serum YKL-40 level for recurrent pneumonia.

RESULTSThe recurrent pneumonia group had a significantly higher serum YKL-40 level than the acute pneumonia and control groups (P<0.05). The acute pneumonia group had a significantly higher serum YKL-40 level than the control group (P<0.05). Serum levels of IgG and complement 4 in the recurrent pneumonia group were significantly lower than in the acute pneumonia group (P<0.05). Serum YKL-40 level was negatively correlated with serum IgG level (r=-0.309, P=0.047) and serum complement 4 level (r=-0.324, P=0.039). The area under the ROC curve of serum YKL-40 level for diagnosing recurrent pneumonia was 0.958 (95%CI: 0.921-0.994).

CONCLUSIONSHumoral immune function is low in children with recurrent pneumonia. Serum YKL-40 may be involved in the occurrence of recurrent pneumonia and can be used as a reference index for diagnosing recurrent pneumonia.

Child, Preschool ; Chitinase-3-Like Protein 1 ; blood ; Complement C4 ; analysis ; Female ; Humans ; Immunity, Humoral ; Immunoglobulin G ; blood ; Male ; Pneumonia ; immunology ; Recurrence

BackgroundAcute coronary syndrome (ACS) is closely related to unstable plaques and secondary thrombosis. The inflammatory cells in plaques and their inflammatory products may be the cause for plaque instability and ruptures. The study aimed to disclose the changes of inflammatory factors including serum intracellular adhesion molecule-1 (ICAM-1), chitinase-3-like protein 1 (YKL-40), and lipoprotein-associated phospholipase A2 (Lp-PLA2) in patients with ACS and its clinical significance.

MethodsA total of 120 patients with coronary heart disease (CHD) were categorized into 2 groups: 69 with ACS and 51 with stable angina pectoris (SAP); 20 patients with chest pain and normal angiography served as a control group. The 120 patients with CHD were categorized into single-vessel disease group, double-vessel disease group, and three-vessel disease group based on the number of coronary artery stenosis. The severity of coronary artery stenosis was quantified based on coronary angiography using Gensini score. They were further divided into mild CHD group with its Gensini score <26 (n = 36), moderate CHD group with its Gensini score being 26-54 (n = 48) and severe CHD group with its Gensini score >54 (n = 36). Serum levels of ICAM-1, YKL-40, and Lp-PLA2 of different groups were determined by enzyme-linked immunosorbent assay. Correlation between ICAM-1, YKL-40, Lp-PLA2, and Gensini score was analyzed.

ResultsThe levels of serum inflammatory factors ICAM-1, YKL-40, and Lp-PLA2 were significantly higher in the ACS group than those in control group and SAP group (all P < 0.05); and compared with control group, no significant difference was observed in terms of the serum ICAM-1, YKL-40, and Lp-PLA2 levels in the SAP group (P > 0.05).The levels of serum ICAM-1, YKL-40, and Lp-PLA2 were not significantly different among control group, single-vessel disease group, double-vessel disease group, and three-vessel disease group (all P > 0.05). The levels of serum ICAM-1, YKL-40, and Lp-PLA2 were not significantly different among control group, mild CHD group (Gensini score <26), moderate CHD group (Gensini score 26-54), and severe CHD group (Gensini score >54) (all P > 0.05). Nonparametric Spearman correlation analysis showed that the levels of serum ICAM-1, YKL-40, and Lp-PLA2 were not correlated with the Gensini score in CHD patients (r = 0.093, r = -0.149, and r = -0.085, all P > 0.05; respectively).

ConclusionsThe serum levels of ICAM-1, YKL-40, and Lp-PLA2 were correlated with different clinical types of CHD, but not well correlated the severity and extent of artery stenosis, suggesting that ICAM-1, YKL-40, and Lp-PLA2 might be involved in occurrence of instability of atherosclerotic plaque, and might reflect the severity of CHD mostly through reflecting the plaque stability.

1-Alkyl-2-acetylglycerophosphocholine Esterase ; metabolism ; Acute Coronary Syndrome ; blood ; immunology ; metabolism ; Adult ; Aged ; Chitinase-3-Like Protein 1 ; metabolism ; Coronary Angiography ; Coronary Disease ; blood ; immunology ; metabolism ; Humans ; Intercellular Adhesion Molecule-1 ; metabolism ; Middle Aged