YKL-40 Protein Research Articles

Hippocampal YKL-40 expression in rats after status epilepticus

ObjectiveThis study aims to investigate rat hippocampal cartilage glycoprotein-39 (YKL-40) expression levels following status epilepticus (SE), and the potential mechanism of YKL-40 in SE-induced neuronal injury. MethodsSeventy-two healthy adult male Sprague-Dawley rats were randomly assigned into two groups: control and SE groups. A lithium chloride-pilocarpine SE model was established, and the control group was injected with sodium chloride. The hippocampus was assessed at three, six, 12, 24 and 72h after SE. YKL-40 protein was detected via immunohistochemistry (n=6). Cellular YKL-40/neuronal nuclei antigen (NeuN) expression levels were determined with double immunofluorescence. YKL-40 mRNA was detected via quantitative real-time polymerase chain reaction (qRT-PCR, n=6). ResultsYKL-40 immunoreactivity was poor and was mainly localized to the cytoplasm within hippocampal CA3/CA4 neurons with limited immunoreactivity in the nucleus in the control group. Following SE, YKL-40 immunoreactivity exhibited a diffused distribution throughout the cytoplasm in neurons and increased distribution in the nucleus. CA3 and CA4 YKL-40 protein expression significantly increased at six hours post-SE (P<0.05), peaked at 12h (P<0.01), and decreased at 24h (P<0.05) and 72h (P<0.05) in the SE group, compared with the control group. Double-label immunofluorescence of YKL-40/NeuN exhibited a hippocampal CA3/CA4 neuron location. Furthermore, SE induced a significant increase inYKL-40 mRNA at six, 24, or 72h (P<0.05); which peaked at 12h (P<0.01). ConclusionsYKL-40 was expressed in neurons, and elevated rat hippocampal YKL-40 expression levels may be involved in the pathogenesis of injury following SE.

Sputum Gene Expression of IL-13 Receptor α2 Chain Correlates with Airflow Obstruction and Helper T-Cell Type 2 Inflammation in Asthma.

BRP-39/YKL-40 is a chitinase-like protein that plays a critical role in IL-13-induced inflammation. It correlates positively with asthma severity and airway remodeling ( 1 ) via binding to IL-13 receptor α2 chain (IL-13Rα2). Because the relationship of IL-13Rα2 to human asthma has never been evaluated previously, we sought to determine the relationship between IL-13Rα2, YKL-40, and asthma. We evaluated 112 patients (69% women) with a mean age of 46.7 years. Subjects completed an asthma phenotyping protocol that included analysis of sputum gene expression by Affymetrix 1.0 ST gene array (Affymetrix, Santa Clara, CA) and YKL-40 protein levels. IL-13Rα2 gene expression was readily detectable in the sputum and correlated negatively with prebronchodilator (BD) FEV1 (rs = -0.282, P < 0.01), post-BD FEV1 (rs = -0.268, P < 0.01), pre-BD FEV1/FVC ratio (rs = -0.228, P < 0.05), and post-BD FEV1/FVC ratio (rs = -0.242, P < 0.01). IL-13Rα2 gene expression correlated positively with gene expression of IL-13 (rs = 0.484, P < 0.001), IL-5 (rs = 0.237, P < 0.05), and IL-8 (rs = 0.218, P < 0.05). Regression analysis showed that the post-BD FEV1/FVC ratio is significantly associated with IL-13Rα2 expression and CHI3L1 expression in sputum after controlling for IL-4, IL-5, IL-13, and transforming growth factor-β1 gene expression (all P < 0.01). Sputum YKL-40 gene expression positively correlated with IL-8 expression (rs = 0.357, P < 0.001) and negatively correlated with pre- and post-BD FEV1/FVC ratios (rs = -0.299, P < 0.001 and rs = -0.305, P < 0.01, respectively). Sputum and serum YKL-40 protein levels were not associated with IL-13Rα2 expression. This analysis demonstrates that IL-13Rα2 is associated with reduced lung function, helper T-cell type 2 gene expression, and airflow obstruction in the airway of individuals with asthma, which might in turn be driven by airway remodeling. Future studies will be required to define the proinflammatory and remodeling effects of this receptor that up to now has been considered solely a modulator of IL-13-induced inflammation.

Serum YKL-40/chitinase 3-like protein 1 level is an independent predictor of atherosclerosis development in patients with obstructive sleep apnea syndrome.

The inflammatory process plays an important role in the development of cardiovascular complications in patients with obstructive sleep apnea syndrome (OSAS). YKL-40/chitinase 3-like protein 1 is a novel biomarker of systemic inflammation. This study aimed to investigate whether carotid intima-media thickness (CIMT), a useful marker for early atherosclerosis, is associated with serum YKL-40/chitinase 3-like protein 1 levels in patients with normotensive and nondiabetic OSAS. The study included 40 OSAS patients and 40 age- sex- and body mass index-matched healthy controls. Serum YKL-40 levels were detected by enzyme-linked immunosorbent assay. CIMT was measured by B-mode ultrasound. The patients with OSAS had significantly increased CIMT and higher YKL-40 and high sensitivity C-reactive protein (hsCRP) levels than those of the controls. CIMT was strongly correlated with serum YKL-40 levels (r=0.694, p<0.001), hsCRP (r=0.622, p<0.001), age (r=0.525, p=0.001), and weakly correlated with apnea-hypopnea index (AHI) (r=0.365, p=0.021) and the percentage of recording time spent (PRTS) of oxygen saturation<90% (r=0.488, p=0.001). Moreover, it was detected that serum YKL-40 levels were strongly correlated with AHI (r=0.617, p<0.001), and weakly correlated with SaO2<90% of PRTS (r=0.394, p=0.012) and hsCRP (r=0.486, p=0.001). In multiple regression analyses, age and serum levels of YKL-40 and hsCRP were found to be independent predictors of CIMT. In patients with OSAS, CIMT was increased. This increase was associated with serum YKL-40 level. Increased serum level of YKL-40 may be an early predictor of atherosclerosis development in patients with OSAS.

Study of serum YKL-40 in children with bronchial asthma

BackgroundSerum YKL-40 (chitinase-3-like-1) has recently been found to be either the cause or a biomarker for asthma. This study quantifies serum levels of YKL-40 in asthmatic children and evaluates the relationship between YKL-40 and asthma severity. MethodsWe quantified serum YKL-40 levels in two groups of asthmatic children (aged between 2 and 12years). Group 1 (n: 30) in between the attack (stable group) and group 2 (n: 30) during the exacerbation (acute attack group). Serum YKL-40 was measured by enzyme-linked immunosorbent assay (ELIZA) Kits (WKEA MED SUPPLIES CORP). We measured blood eosinophils and peak expiratory flow rate for children >5years. ResultsSerum levels of YKL-40 were significantly elevated in the acute asthma group and in the stable asthma group compared to the control group (673.92±24.23ng/ml, 552.73±57.34ng/ml, 136.17±53.14) respectively, P<0.001. YKL-40 levels were correlated positively with blood eosinophils in the stable group (ρ=0.67, P<0.001) and in the acute attack group (ρ=0.76, P<0.001). It is inversely correlated with PEFR in the stable asthma group (ρ=−0.83, P<0.001) and in the acute asthma group (ρ=−0.88, P<0.001). ConclusionsSerum YKL-40 protein was found in increased quantities in patients with asthma in whom the protein level correlated positively with the severity of disease so our data concluded that YKL-40 could be a valuable biomarker for asthma diagnosis and prognosis.

Expression of YKL-40 and MIP-1a proteins in exudates and transudates: biomarkers for differential diagnosis of pleural effusions? A pilot study.

BackgroundYKL-40 is an extracellular matrix glycoprotein with a significant role in tissue inflammation and remodeling. MIP-1a has chemotactic and pro-inflammatory properties, and is induced by YKL-40 in several lung disorders. The aim of this study was to determine the levels of YKL-40 and MIP-1a in blood serum and pleural fluids of various pulmonary diseases, and to evaluate their potential role as differential diagnosis biomarkers.MethodsWe recruited 60 patients (age: 62.5 ± 20.6 years) with pleural effusions: 49 exudates and 11 transudates (T). Exudates were further classified based on the underlying disease: ten with tuberculosis (TB), 13 with lung cancer (LCa), 15 with metastatic cancer (MCa) of non-lung origin and 11 with parapneumonic (PN) effusions. YKL-40 and MIP-1a levels were measured by ELISA.ResultsPleural YKL-40 levels (ng/ml) were similar among all patient groups (TB: 399 ± 36, LCa: 401 ± 112, MCa: 416 ± 34, PN: 401 ± 50, T: 399 ± 42, p = 0.92). On the contrary, YKL-40 was significantly lower in the serum of TB patients (TB: 58 ± 22, LCa: 212 ± 106, MCa: 254 ± 140, PN: 265 ± 140, T: 229 ± 123, p < 0.001). Pleural MIP-1a protein levels (ng/ml) were statistically lower only in patients with LCa (TB: 25.0 ± 20.2, LCa: 7.3 ± 6.0, MCa: 16.1 ± 14.9, PN: 25.4 ± 27.9, T: 18.5 ± 7.9, p = 0.012), a finding also observed in serum MIP-1a levels (TB: 17.1 ± 7.6, LCa: 9.4 ± 7.0, MCa: 28.7 ± 28.7, PN: 33.3 ± 24.0, T: 22.9 ± 8.7, p = 0.003).ConclusionsOur data suggest that both YKL-40 and MIP-1a, particularly in serum, could prove useful for the differentiation of pleural effusions in clinical practice, especially of TB or LCa origin. However, large-scale studies are needed to validate these findings.

Regulation of YKL-40 expression by corticosteroids: effect on pro-inflammatory macrophages in vitro and its modulation in COPD in vivo.

BackgroundMacrophages constitute a heterogeneous cell population with pro- (MΦ1) and anti-inflammatory (MΦ2) cells. The soluble chitinase-like-protein YKL-40 is expressed in macrophages and various other cell types, and has been linked to a variety of inflammatory diseases, including COPD. Dexamethasone strongly reduces YKL-40 expression in peripheral blood mononuclear cells (PBMC) in vitro. We hypothesized that: a) YKL-40 is differentially expressed by MΦ1 and MΦ2, b) is decreased by corticosteroids and c) that long-term treatment with inhaled corticosteroids (ICS) affects YKL-40 levels in serum and sputum of COPD patients.MethodsMonocytes of healthy subjects were cultured in vitro for 7 days with either GM-CSF or M-CSF (for MΦ1 and MΦ2, respectively) and stimulated for 24 h with LPS, TNFα, or oncostatin M (OSM). MΦ1 and MΦ2 differentiation was assessed by measuring secretion of IL-12p40 and IL-10, respectively. YKL-40 expression in macrophages was measured by quantitative RT-PCR (qPCR) and ELISA; serum and sputum YKL-40 levels were analyzed by ELISA.ResultsPro-inflammatory MΦ1 cells secreted significantly more YKL-40 than MΦ2, which was independent of stimulation with LPS, TNFα or OSM (p < 0.001) and confirmed by qPCR. Dexamethasone dose-dependently and significantly inhibited YKL-40 protein and mRNA levels in MΦ1. Serum YKL-40 levels of COPD patients were significantly higher than sputum YKL-40 levels but were not significantly changed by ICS treatment.ConclusionsYKL-40 secretion from MΦ1 cells is higher than from MΦ2 cells and is unaffected by further stimulation with pro-inflammatory agents. Furthermore, YKL-40 release from cultured monocyte-derived macrophages is inhibited by dexamethasone especially in MΦ1, but ICS treatment did not change YKL-40 serum and sputum levels in COPD. These results indicate that YKL-40 expression could be used as a marker for MΦ1 macrophages in vitro, but not for monitoring the effect of ICS in COPD.Trial registrationClinicalTrials.gov, registration number: NCT00158847

Clinical correlation between serum YKL-40 protein level and recurrence of non-muscle invasive bladder cancer.

To explore the clinical correlation between serum YKL-40 protein level and recurrence of non-muscle invasive bladder cancer (NMIBC). Totally 76 NMIBC patients (including 34 patients with confirmed recurrence and 42 patients without recurrence during the 2-year post-operative follow-up) and 31 healthy volunteers were recruited in this study. Blood samples were collected early in the morning, and serum YKL-40 protein levels of all these patients were analysed by using enzyme-linked immunosorbent assay (ELISA). Serum YKL-40 protein levels were significantly higher in NMIBC patients than in healthy controls (P<0.001). Meanwhile, serum YKL-40 protein levels were found to be significantly higher in patients with recurrent NMIBC than those without tumor recurrence (P=0.001). Serum YKL-40 protein can be a reliable molecular marker for the clinical diagnosis of NMIBC recurrence. In particular, it can inform the post-operative management.

Changes in the gene expression of co-cultured human fibroblast cells and osteosarcoma cells: the role of microenvironment.

The progression of malignant tumors does not depend exclusively on the autonomous properties of cancer cells; it is also influenced by tumor stroma reactivity and is under strict microenvironmental control. By themselves, stromal cells are not malignant, and they maintain normal tissue structure and function. However, through intercellular interactions or by paracrine secretions from cancer cells, normal stromal cells acquire abnormal phenotypes that sustain cancer cell growth and tumor progression. In their dysfunctional state, fibroblast and immune cells produce chemokines and growth factors that stimulate cancer cell growth and invasion. In our previous work, we established an in vitro model based on a monolayer co-culture system of healthy human fibroblasts (HFs) and human osteosarcoma cells (the MG-63 cell line) that simulates the microenvironment of tumor cells and healthy cells. The coexistence between MG-63 cells and HFs allowed us to identify the YKL-40 protein as the main marker for verifying the influence of tumor cells grown in contact with healthy cells. In this study, we evaluated the interactions of HFs and MG-63 cells in a transwell co-culture system over 24 h, 48 h, 72 h, and 96 h. We analyzed the contributions of these populations to the tumor microenvironment during cancer progression, as measured by multiple markers. We examined the effect of siRNA knockdown of YKL-40 by tracking the subsequent changes in gene expression within the co-culture. We validated the expression of several genes, focusing on those involved in cancer cell invasion, inflammatory responses, and angiogenesis: TNF alpha, IL-6, MMP-1, MMP-9, and VEGF. We compared the results to those from a transwell co-culture without the YKL-40 knockdown. In a pro-inflammatory environment promoted by TNF alpha and IL-6, siRNA knockdown of YKL-40 caused a down-regulation of VEGF and MMP-1 expression in HFs. These findings demonstrated that the tumor microenvironment has an influence on the gene expression of healthy surrounding tissues and on the process of tumorigenicity and it is emerging as attractive targets for therapeutic strategies.

New inflammatory markers for prediction of non-dipper blood pressure pattern in patients with essential hypertension: Serum YKL-40/Chitinase 3-like protein 1 levels and echocardiographic epicardial adipose tissue thickness

The aim of the present study was to investigate whether YKL-40 levels and epicardial adipose tissue (EAT) thickness were associated with non-dipping pattern in essential hypertension (HT). Age- and sex-matched 40 dipper hypertensive patients and 40 non-dipper hypertensive patients were included in the study. Non-dippers had significantly increased EAT thickness and higher YKL-40 and high-sensitivity C-reactive protein levels than dippers. Multivariate logistic regression analysis showed that the EAT thickness and serum levels of YKL-40 and high-sensitivity C-reactive protein were independent predictors of non-dipping pattern in essential HT. In essential HT, presence of non-dipping pattern is associated with increased inflammatory response.

YKL-40 protein correlates with the phenotype of asthma.

PurposeYKL-40 is a chitinase-like protein found to correlate with asthma as well as numerous infectious and autoimmune diseases or cancer. The aim of the present study was to investigate the role of YKL-40 as a possible marker of asthma and its associations with factors differentiating phenotypes of asthma.MethodsThe study group comprised 167 patients, including 116 women and 51 men aged 18–88 years with chronic asthma. The control group comprised 81 healthy individuals, including 50 women and 31 men aged 19–86 years. In every participant, medical history was taken; spirometry and skin prick tests were performed. YKL-40 was determined in sera by means of ELISA test.ResultsMean serum YKL-40 level was 59.7 ng/ml (53.6–65.7 ng/ml; 95 % CI) with significant difference between asthmatics and healthy controls (mean values: 66.8 ± 53.8 vs. 44.9 ± 29.4 ng/ml; p < 0.001). In asthmatics, the level was significantly higher in subgroup with poor control of symptoms and exacerbations (91.8 ± 57.1 ng/ml) compared to stable asthmatics (59.6 ± 50.8 ng/ml; p < 0.001) as well as in atopic compared to non-atopic asthmatics (77.2 ± 53.9 vs. 61.1 ± 57.8 ng/ml; p < 0.001). Mean YKL-40 level in obese asthmatics was 135.6 ng/ml compared to 50.0 ng/ml in non-obese (p < 0.001). When phenotypes of early-onset atopic, late-onset non-atopic, and obesity-related asthma were compared, YKL-40 levels were 80.62 ± 46.9, 51.5 ± 24.9, and 168.1 ± 71.5 ng/ml, respectively (p < 0.05).ConclusionAlthough YKL-40 is not a specific marker for asthma, it correlates with some clinical features such as exacerbation, level of control, atopy, and obesity.

Changes in the gene expression of co-cultured human fibroblast cells and osteosarcoma cells: the role of microenvironment

The progression of malignant tumors does not depend exclusively on the autonomous properties of cancer cells; it is also influenced by tumor stroma reactivity and is under strict microenvironmental control. By themselves, stromal cells are not malignant, and they maintain normal tissue structure and function. However, through intercellular interactions or by paracrine secretions from cancer cells, normal stromal cells acquire abnormal phenotypes that sustain cancer cell growth and tumor progression. In their dysfunctional state, fibroblast and immune cells produce chemokines and growth factors that stimulate cancer cell growth and invasion. In our previous work (1), we established an in vitro model based on a monolayer co-culture system of healthy human fibroblasts (HFs) and human osteosarcoma cells (the MG-63 cell line) that simulates the microenvironment of tumor cells and healthy cells. The coexistence between MG-63 cells and HFs allowed us to identify the YKL-40 protein as the main marker for verifying the influence of tumor cells grown in contact with healthy cells. In this study, we evaluated the interactions of HFs and MG-63 cells in a transwell co-culture system over 24 h, 48 h, 72 h, and 96 h. We analyzed the contributions of these populations to the tumor microenvironment during cancer progression, as measured by multiple markers. We examined the effect of siRNA knockdown of YKL- 40 by tracking the subsequent changes in gene expression within the co-culture. We validated the expression of several genes, focusing on those involved in cancer cell invasion, inflammatory responses, and angiogenesis: TNF alpha, IL-6, MMP-1, MMP- 9, and VEGF. We compared the results to those from a transwell co-culture without the YKL-40 knockdown. In a pro-inflammatory environment promoted by TNF alpha and IL-6, siRNA knock- down of YKL-40 caused a down-regulation of VEGF and MMP-1 expression in HFs. These results suggest that the tumor microenvironment has an influence on the protein expression of healthy surrounding tissues and on the process of tumorigenicity. The mechanisms of the microenvironment are emerging as attractive targets for therapeutic strategies.

Association between serum YKL-40 level and dysglycemia in cystic fibrosis

BackgroundYKL-40, a chitinase-like protein, is a biomarker for type 1 and type 2 diabetes prognosis. We hypothesized that YKL-40 protein levels are elevated in CF patients with dysglycemia. MethodsSeventeen healthy control subjects and 66 CF patients were prospectively recruited and subjected to an oral glucose tolerance test. In all participants, fasting serum YKL-40 was compared between control and CF patients and between normal glucose-tolerant patients (NG-CF) and CF patients with dysglycemia (DG-CF). A Botnia clamp procedure was performed on a subset of patients for each group to determine the impact of acute increases of either glucose or insulin on YKL-40 concentration. ResultsCF patients had higher serum YKL-40 values than the controls (113 [49;288] vs. 38 [30;50] ng/ml, p<0.001). YKL-40 concentrations in CF patients were mainly increased in the DG-CF group, who had significantly higher values: 213 [93;383] vs. 67 [27;97] ng/ml in the NG-CF group, p<0.001). No significant modulation of YKL-40 concentration was observed in serum of CF (NG or DG-CF) or non-CF patients, after acute exposure to glucose or insulin. ConclusionsHigher serum YKL-40 levels in CF patients are significantly associated with dysglycemia. The increase in YKL-40 is potentially associated with an inflammatory response resulting from chronic glucose intolerance or CF disease evolution.

Cerebrospinal fluid level of YKL-40 protein in preclinical and prodromal Alzheimer's disease.

An increase in YKL-40 levels seems to correlate with disease severity and poor prognosis in many diseases, including several neurodegenerative diseases such as multiple sclerosis, amyotrophic lateral sclerosis, and Alzheimer's disease (AD). Specifically, YKL-40 protein is increased in mild AD with respect to controls, both in cerebrospinal fluid (CSF) and plasma. We hypothesize that subjects in the preclinical (Pre-AD) and prodromal (Prod-AD) stage of AD could already present an increase in CSF YKL-40 levels with respect to healthy controls and idiopathic REM sleep behavior disorder (iRBD) subjects, included as a control group of a distinct neurological disease. We measured CSF YKL-40 levels using a commercial ELISA kit in a cohort of 95 subjects, consisting of controls (n = 43), Pre-AD (n = 18), Prod-AD (n = 22), and iRBD (n = 12) subjects. We explored for possible correlations of YKL-40 levels with demographic characteristics, a wide battery of neuropsychological tests, and the AD CSF biomarkers: amyloid-β42 (Aβ42), total-tau protein (t-tau), and phosphorylated-tau protein (p-tau). We detected statistically significant differences between Prod-AD patients and controls. YKL-40 levels showed a significant correlation with t-tau and p-tau levels in the predementia AD continuum and the Pre-AD group. We also observed significant correlations with the MMSE, FCSRT, and M@T tests within the AD continuum, but not in iRBD subjects. Our data suggest that CSF YKL-40 levels, although not useful as a diagnostic marker for Prod-AD, may be a valuable marker to detect early physiopathological changes potentially linked with the neurodegenerative process.

CHI3L1 polymorphisms associate with asthma in a Taiwanese population.

BackgroundA genome-wide association study uncovered Chitinase 3 like 1 (CHI3L1) as a candidate gene for asthma susceptibility. CHI3L1, which encodes the YKL-40 protein, is associated with asthma in Western European and American populations and with atopy in a Korean population. However, asthma-associated polymorphisms remain unknown for a Taiwanese population.MethodsWe enrolled 628 adult asthmatic patients and 1:1 age-sex matched community-based controls in southern Taiwan and performed a combined effect sizes analysis to test if CHI3L1 polymorphisms were related to genetic risks for asthma in the Asian population. Ten tagSNP polymorphisms for the CHI3L1 gene were selected from the HapMap database and genotyped using a TaqMan allelic discrimination assay.ResultsAdjusted odds ratios of the CHI3L1 rs1538372 CC genotype (aOR = 1.97, 95% CI: 1.23–3.14) and the rs10399931 GG genotype (aOR = 1.77, 95% CI: 1.13–2.77) were significantly associated with asthma in the Taiwanese populations. Predictive values of forced expiratory volume in the first second of the forced vital capacity (12.37%, P = 0.03) and of forced vital capacity (12.10%, P = 0.036) decreased in conjunction with an increase in YKL-40 levels among CHI3L1 rs1538372 CC carriers; these values were 16.1% (P = 0.004) and 14.5% (P = 0.011), respectively, among CHI3L1 rs10399931 GG carriers. Furthermore, steroid use by asthma patients did not affect serum YKL-40 levels, but both polymorphisms had significant effects on YKL-40 levels in asthma patients who used steroids.ConclusionsOur findings suggest that the CHI3L1 polymorphisms rs1538372 and rs10399931 can be used as genetic markers for predicting asthma risk in the Taiwanese population.

Establishment of using serum YKL-40 and SCCA in combination for the diagnosis of patients with esophageal squamous cell carcinoma.

BackgroundElevated serum YKL-40 levels have been observed in various cancers. We evaluated the diagnostic performance of serum YKL-40 alone or in combination with the CEA, CYFRA21-1 and SCCA tumor markers for patients with esophageal squamous cell carcinoma (ESCC).MethodsYKL-40 was detected in ESCC cell lines and tissues by real-time RT-PCR, Western blotting and ELISA. YKL-40 protein expression was determined in 20 ESCC tumor tissues using immunohistochemistry. Serum YKL-40 was measured by ELISA in 126 healthy donors, 59 patients with benign esophageal diseases and 150 patients with ESCC. Serum CEA, CYFRA21-1 and SCCA were determined by electrochemiluminescence.ResultsYKL-40 mRNA and protein were observed in ESCC cancer cell lines, tissues and cell culture media, respectively. YKL-40 expression was observed in 17 of 20 ESCC samples (85%). Serum YKL-40 concentration was significantly elevated in patients with ESCC (Range: 6.95-502.10 ng/ml) compared with patients with benign diseases (Range: 1.21-429.30 ng/ml; P = 0.038) and healthy controls (Range: 2.56-132.26 ng/ml; P < 0.001). ROC curves demonstrated that serum YKL-40 has a sensitivity of 72.70%, a specificity of 84.13% and an AUC of 0.874 for the diagnosis of ESCC, which was superior to CEA (Sen: 8.00%; Spe: 96.80%, AUC = 0.652), CYFRA21-1 (Sen: 40.00%; Spe: 92.06%, AUC = 0.746) and SCCA (Sen: 32.67%; Spe: 94.44%, AUC = 0.789). The YKL-40 and SCCA combination was better for diagnosing ESCC (Sen: 82.00%, Spe: 79.37%, PPV: 82.55 and NPV: 78.74; AUC = 0.917) than the YKL-40 and CEA combination (Sen: 74.00%, Spe: 83.20%, PPV: 84.09 and NPV: 72.73; AUC = 0.877), the YKL-40 and CYFRA21-1 combination (Sen: 82.00%, Spe: 77.78%, PPV: 81.46% and NPV: 78.40%; AUC = 0.897) or the CEA, CYFRA21-1 and SCCA combination (Sen: 56.67%, Spe: 84.80%, PPV: 81.73 and NPV: 61.99; AUC = 0.831). Associations between serum YKL-40 levels and the clinic characteristics of ESCC were not significant, with the exception of age (p = 0.001).ConclusionsESCC tumor cells and tissues express YKL-40. Serum YKL-40 may be a potential biomarker for ESCC. Serum YKL-40 in combination with SCCA significantly increases the sensitivity of detecting ESCC.

Increased Chitotriosidase Activities in Patients with Rheumatoid Arthritis: A Possible Novel Marker?

Abstract Background: Chitotriosidase and YKL-40 are well-known in humans as Glyco_18 domain-containing proteins that are the common feature of mammalian chitinases and chitinaselike proteins. Previously, increased levels of YKL-40 were found correlated with the disease activity of rheumatoid arthritis. However, serum chitotriosidase activity in rheumatoid arthritis is not known yet. The aim of this study was to determine YKL-40 and chitotriosidase in patients with rheu - matoid arthritis and to compare these markers with traditi - onal ones such as C-reactive protein and erythrocyte sedimentation rate. Methods: Chitotriosidase, YKL-40 and C-reactive protein were measured in serum samples from 27 patients with rheumatoid arthritis and 27 healthy people. Chitotriosidase, YKL-40, C-reactive protein, and erythrocyte sedimentation rate were determined by a fluorometer, ELISA, nephelometer, and Western Green method, respectively. Results: Serum chitotriosidase activities and YKL-40 levels were higher in rheumatoid arthritis group than in control. A significant positive correlation was found between chitotriosidase and YKL-40. In ROC analysis, the areas under curves for chitotriosidase, C-reactive protein, erythrocyte sedimentation rate, and YKL-40 were 0.96, 0.84, 0.76, and 0.65, respectively. Area under the curve for chitotriosidase was significantly higher than the area for erythrocyte sedimentation rate (p=0.005) and for YKL-40 (p=0.0001), but not for Creactive protein (p=0.055). Conclusions: Serum chitotriosidase was significantly in creas - ed in patients with rheumatoid arthritis. Among all the param - eters evaluated, chitotriosidase was the most sensitive and specific one. Comprehensive studies covering larger populations are needed to elucidate the relationship bet ween chitinases, in particular chitotriosidase and rheumatoid arthritis.

Neurochemical Evidence of Potential Neurotoxicity After Prophylactic Cranial Irradiation

To examine whether cerebrospinal fluid biomarkers for neuroaxonal damage, neuroglial activation, and amyloid β-related processes could characterize the neurochemical response to cranial radiation. Before prophylactic cranial irradiation (PCI) of patients with small cell lung cancer, each patient underwent magnetic resonance imaging of the brain, lumbar puncture, and Mini-Mental State Examination of cognitive function. These examinations were repeated at approximately 3 and 12 months after radiation. The major findings were as follows. (1) Cerebrospinal fluid markers for neuronal and neuroglial injury were elevated during the subacute phase after PCI. Neurofilament and T-tau increased 120% and 50%, respectively, after PCI (P<.05). The same was seen for the neuroglial markers YKL-40 and glial fibrillary acidic protein, which increased 144% and 106%, respectively, after PCI (P<.05). (2) The levels of secreted amyloid precursor protein-α and -β were reduced 44% and 46%, respectively, 3 months after PCI, and the levels continued to decrease as long as 1 year after treatment (P<.05). (3) Mini-Mental State Examination did not reveal any cognitive decline, indicating that a more sensitive test should be used in future studies. In conclusion, we were able to detect radiation therapy-induced changes in several markers reflecting neuronal injury, inflammatory/astroglial activation, and altered amyloid precursor protein/amyloid β metabolism, despite the low number of patients and quite moderate radiation doses (20-30 Gy). These changes are hypothesis generating and could potentially be used to assess the individual risk of developing long-term symptoms of chronic encephalopathy after PCI. This has to be evaluated in large studies with extended clinical follow-up and more detailed neurocognitive assessments.

Brain Barriers and a Subpopulation of Astroglial Progenitors of Developing Human Forebrain Are Immunostained for the Glycoprotein YKL-40

YKL-40, a glycoprotein involved in cell differentiation, has been associated with neurodevelopmental disorders, angiogenesis, neuroinflammation and glioblastomas. We evaluated YKL-40 protein distribution in the early human forebrain using double-labeling immunofluorescence and immunohistochemistry. Immunoreactivity was detected in neuroepithelial cells, radial glial end feet, leptomeningeal cells and choroid plexus epithelial cells. The subpial marginal zone was YKL-40-positive, particularly in the hippocampus, from an early beginning stage in its development. Blood vessels in the intermediate and subventricular zones showed specific YKL-40 reactivity confined to pericytes. Furthermore, a population of YKL-40-positive, small, rounded cells was identified in the ventricular and subventricular zones. Real-time quantitative RT-PCR analysis showed strong YKL-40 mRNA expression in the leptomeninges and the choroid plexuses, and weaker expression in the telencephalic wall. Immunohistochemistry revealed a differential distribution of YKL-40 across the zones of the developing telencephalic wall. We show that YKL-40 is associated with sites of the brain barrier systems and propose that it is involved in controlling local angiogenesis and access of peripheral cells to the forebrain via secretion from leptomeningeal cells, choroid plexus epithelium and pericytes. Furthermore, we suggest that the small, rounded, YKL-40-positive cells represent a subpopulation of astroglial progenitors, and that YKL-40 could be involved in the differentiation of a particular astrocytic lineage.

The Effect of Recombinant Human Interleukin-6 on Osteogenic Differentiation and YKL-40 Expression in Human, Bone Marrow–Derived Mesenchymal Stem Cells

Human mesenchymal stem cells are an attractive cell source for tissue engineering and regenerative medicine applications, especially because of their differentiation potential toward the mesenchymal lineage. Furthermore, this cell type participates in the regeneration of tissue damage and plays an important role in immunity. Similarly, chitinase-like proteins have been proposed to aid in tissue remodeling, inflammation, and differentiation processes. The chitinase-like protein YKL-40 in particular is indicated in preventing damage to the extracellular matrix in response to proinflammatory cytokines, even though its biological function remains speculative. Finally, interleukin (IL)-6, a pleiotropic acute phase protein, participates in the regulation of bone turnover and immunoregulation. The physiological role of IL-6 in bone homeostasis is complex, exerting different effects on osteoblasts and osteoclasts depending on their differentiation stage. The aim of this study was to determine the effect of recombinant human IL-6 (5 ng/mL) on YKL-40 expression and osteogenic differentiation of human mesenchymal stem cells. Recombinant human IL-6 induced a donor-dependent change in mineralization and significantly promoted YKL-40 protein secretion. However, YKL-40 gene expression remained unaffected, and no statistically significant differences in the expression of osteogenic marker genes could be observed.

The significance of YKL-40 protein in liver fibrosis

The aims of this review are to describe the present knowledge about YKL-40 protein, discuss its relation to liver fibrosis, and to look ahead at future perspectives of YKL-40 research. Liver fibrosis is characterized by excess collagen deposition, decreased extracellular matrix degradation and activation of hepatic stellate cells. Therefore, advancement in the identification of liver fibrosis biomarkers with diagnostic and prognostic values becomes an important tool for future molecular therapy. The molecular basis of YKL-40 in liver fibrosis is unknown. A PubMed database search was performed for studies of YKL-40 in liver injury and fibrosis. YKL-40 is an inflammatory glycoprotein involved in endothelial dysfunction by promoting chemotaxis, cell attachment and migration, reorganization, and tissue remodeling as a response to endothelial damage. Several studies demonstrate that elevated serum YKL-levels are independently associated with the presence of endothelial damage and even higher YKL-40 levels are documented in liver fibrosis. YKL-40 may play a key role in liver injury and fibrosis.