The chitinase 3-like protein human cartilage glycoprotein 39 (HC-gp39) stimulates proliferation of human connective-tissue cells and activates both extracellular signal-regulated kinase- and protein kinase B-mediated signalling pathways

Transfer of MicroRNA via Macrophage-Derived Extracellular Vesicles Promotes Proneural-to-Mesenchymal Transition in Glioma Stem Cells

Proneural-to-mesenchymal transition (PMT) is a common process in glioblastoma (GBM) progression that leads to increased radiotherapy resistance. However, the mechanism underlying PMT is poorly understood. Here, we found that tumor-associated macrophages triggered PMT in glioma stem cells (GSC) via small extracellular vesicles (sEV). sEVs from monocyte-derived macrophages transferred miR-27a-3p, miR-22-3p, and miR-221-3p to GSCs, and these miRNAs promoted several mesenchymal phenotypes in proneural (PN) GSCs by simultaneously targeting CHD7 We found that CHD7 played a critical role in the maintenance of the PN phenotype, and CHD7 knockdown significantly promoted PMT in GSCs via the RelB/P50 and p-STAT3 pathways. The induction of PMT by sEVs containing miR-27a-3p, miR-22-3p, and miR-221-3p in a xenograft nude mouse model exacerbated radiotherapy resistance and thus decreased the benefits of radiotherapy. Collectively, these findings identified macrophage-derived sEVs as key regulators of PMT in GSCs and demonstrated that CHD7 is a novel inhibitor of PMT.

Possible Prognostic Potential of RANKL and OPG in Metastatic Breast Cancer Egyptian Females

Objectives:

Searching for sensitive, minimally invasive biomarkers that represent tumor-associated changes in the peripheral blood might enable the early diagnosis of breast cancer (BC) and monitoring of tumor progression.

Methods:

Herein, we investigated the association of some circulating biomarkers with the risk of metastasis. In the current study, 115 BC patients which were subdivided into two groups: nonmetastatic breast cancer patients (NMBC) (n=83) and metastatic breast cancer patients (MBC) (n=32), and 79 apparently healthy controls were recruited. Serum protein levels of lysosomal protein transmembrane 4 beta (LAPTM4B), receptor activator of nuclear factor-kappa b (NF-Kb) ligand (RANKL), osteoprotegerin (OPG), vitamin D (VIT D), chitinase-3-like protein 1 (also known as YKL-40), and sirtuin 1 (SIRT1) were assessed in blood samples using ELISA technique.

Results:

The results showed that RANKL and OPG had the highest diagnostic potential for MBC detection, with area under the curve values of 0.97 and 0.94, respectively. Moreover, logistic regression analysis showed that RANKL had the highest differentiation power in the discrimination of MBC from NMBC.

Conclusion:

The study highlighted that measuring RANKL and OPG may be helpful in the early detection of metastasis in Egyptian patients with BC.

Elevated plasma YKL-40 level is found in the dogs with cancer and is related to poor prognosis

YKL-40, a secreted glycoprotein, may serve as an autoantigen, which mediates multiple inflammatory diseases and cancers. A high YKL-40 serum level is correlated with metastasis and poor survival in a variety of human cancers. However, the role of YKL-40 in dogs is still under evaluation. Herein, we examined the associations between plasma YKL-40 level and YKL-40 autoantibody (YAA) titers with malignancy and prognosis in canine cancer. Plasma levels of YKL-40 in healthy dogs (n = 20) and in dogs (n = 82) with cancer were evaluated using enzyme-linked immunosorbent assay. Our results indicated that plasma YKL-40 levels were significantly higher (p < 0.01) in dogs with cancer than in healthy dogs. A significant decrease in the YAA titers was detected in the dogs with cancer when compared with those of the healthy dogs (p < 0.05), although the change was not correlated with the YKL-40 levels. Among the dogs with cancer, plasma YKL-40 levels in the dogs that later relapsed or had metastasis were significantly higher than in the dogs with no signs of relapse (p < 0.01) or metastasis (p <0.05). The relapse and metastasis rates were significantly higher in the high YKL-40 group (> 180 pg/mL) than in the low YKL-40 group (< 180 pg/mL). The results imply that plasma YKL-40 levels might have the potential to be developed as a marker of malignancy progression and prognosis in canine cancers.

NF-κB-mediated inhibition of microRNA-149-5p regulates Chitinase-3-like 1 expression in human airway epithelial cells

Lower respiratory tract infections are among the most common causes of death worldwide. Main pathogens leading to these severe infections are viruses and gram-positive bacteria that activate toll-like receptor (TLR)-mediated immune responses via pathogen-associated molecular patterns. One protective factor induced during infection is Chitinase-3-like 1 (CHI3L1), which exerts various functions, e.g. in host cell proliferation and bacterial counteraction, and has been proposed as a biomarker in several acute and chronic inflammatory conditions. MicroRNAs (miR) have become important regulators of inflammation and infection and are considered therapeutic targets in recent years. However, it is not known whether microRNAs play a role in the regulation of CHI3L1 expression in TLR-mediated respiratory epithelial cell inflammation. In this study, we analysed the pre- and post-transcriptional regulation of CHI3L1 by TLRs in bronchial epithelial cells. Therefore, we stimulated BEAS-2B cells with the bacterial TLR2-ligand lipoteichoic acid or the viral dsRNA analogue poly(I:C). We observed an increase in the expression of CHI3L1, which was dependent on TNF-α-mediated NF-κB activation in TLR2- and TLR3-activated cells. Moreover, TLR2 and - 3 stimulation caused downregulation of the microRNA miR-149-5p, an effect that could be suppressed by inhibiting NF-κB translocation into the nucleus. Luciferase reporter assays identified a direct interaction of miR-149-5p with the CHI3L1 3´untranslated region. This interaction was confirmed by inhibition and overexpression of miR-149-5p in BEAS-2B cells, which altered the expression levels of CHI3L1 mRNA. In summary, miR-149-5p directly regulates CHI3L1 in context of TLR-mediated airway epithelial cell inflammation and may be a potential therapeutic target in inflammation and other diseases.

MicroRNA-24 protects retina from degeneration in rats by down-regulating chitinase-3-like protein 1

MicroRNAs (miRNAs) have been shown to play critical roles in the pathogenesis and progression of degenerative retinal diseases like age-related macular degeneration (AMD). In this study, we first demonstrated that miR-24 plays an important role in maintaining retinal structure and visual function of rats by targeting chitinase-3-like protein 1 (CHI3L1). In the retinal pigment epithelial (RPE) cells of Royal College of Surgeons (RCS) rats, an animal model of genetic retinal degeneration (RD), miR-24 was found lower and CHI3L1 level was higher in comparison with those in Sprague-Dawley (SD) rats. Other changes in the eyes of RCS rats include activated AKT/mTOR and ERK pathways and abnormal autophagy in the RPE cells. Such roles of miR-24 and CHI3L1 were further confirmed in RCS rats by subretinal injection of agomiR-24, which decreased CHI3L1 level and preserved retinal structure and function. Upstream, NF-κB was identified as the regulator of miR-24 in the RPE cells of these rats. On the other hand, in SD rats, intraocular treatment of antagomiR-24 induced pathological changes similar to those in RCS rats. The results revealed the protective roles for miR-24 to RPE cells and a mechanism for RD in RCS rats was proposed: extracellular stress stimuli first activate the NF-κB signaling pathway, which lowers miR-24 expression so that CHI3L1 increased. CHI3L1 sequentially results in aberrant autophagy and RPE dysfunction by activating AKT/mTOR and ERK pathways. Taken together, although the possibility, that the therapeutic effects in RCS rats are caused by other transcriptional changes regulated by miR-24, cannot be excluded, these findings indicate that miR-24 protects rat retina by targeting CHI3L1. Thus, miR-24 and CHI3L1 might be the targets for developing more effective therapy for degenerative retinal diseases like AMD.

YKL-40/CHI3L1 facilitates migration and invasion in HER2 overexpressing breast epithelial progenitor cells and generates a niche for capillary-like network formation

Epithelial to mesenchymal transition (EMT) is a developmental event that is hijacked in some diseases such as fibrosis and cancer. In cancer, EMT has been linked to increased invasion and metastasis and is generally associated with a poor prognosis. In this study, we have compared phenotypic and functional differences between two isogenic cell lines with an EMT profile: D492M and D492HER2 that are both derived from D492, a breast epithelial cell line with stem cell properties. D492M is non-tumorigenic while D492HER2 is tumorigenic. Thus, the aim of this study was to analyze the expression profile of these cell lines, identify potential oncogenes, and evaluate their effects on cellular phenotype. We performed transcriptome and secretome analyses of D492M and D492HER2 and verified expression of selected genes at the RNA and protein level. One candidate, YKL-40 (also known as CHI3L1), was selected for further studies due to its differential expression between D492M and D492HER2, being considerably higher in D492HER2. YKL-40 has been linked to chronic inflammation diseases and cancer, yet its function is not fully understood. Knock-down experiments of YKL-40 in D492HER2 resulted in reduced migration and invasion as well as reduced ability to induce angiogenesis in an in vitro assay, plus changes in the EMT-phenotype. In summary, our data suggest that YKL-40 may provide D492HER2 with increased aggressiveness, supporting cancer progression and facilitating angiogenesis.

Downregulated CHI3L1 alleviates skeletal muscle stem cell injury in a mouse model of sepsis

Sepsis is an acute systemic inflammatory response of the body to microbial infection and a life-threatening condition associated with multiple organ failure. Recent data suggest that sepsis survivors present with long-term myopathy due to the dysfunction of skeletal muscle stem cells and satellite cells. Accumulating studies have implicated chitinase-3-like-1 protein (CHI3L1) in a variety of infectious diseases, specifically sepsis. Therefore, the aim of the present study is to elucidate the potential mechanism by which CHI3L1 is involved in the injury of skeletal muscle stem cells in mouse models of sepsis. An in vitro cell model was developed by lipopolysaccharide (LPS) and in vivo mouse model of sepsis was induced by CRP-like protein (CLP). To elucidate the biological significance behind the silencing of CHI3L1, modeled skeletal muscle stem cells and mice were treated with siRNA against CHI3L1 or overexpressed CHI3L1. Highly expressed CHI3L1 was found in skeletal muscle tissues of mice with sepsis. Besides, siRNA-mediated silencing of CHI3L1 was revealed to increase Bcl-2 expression along with cell proliferation, while diminishing Bax expression, cell apopstosis as well as serum levels of TNF-α, IL-1β, INF-γ, IL-10, and IL-6. Taken conjointly, this present study provided evidence suggesting that downregulation of CHI3L1 has the potential to prevent the injury of skeletal muscle stem cells in mice with sepsis. Collectively, CHI3L1 may serve as a valuable therapeutic strategy in alleviating sepsis.

Overexpression of chitotriosidase and YKL-40 in peripheral blood and sputum of healthy smokers and patients with chronic obstructive pulmonary disease

Background

Despite the absence of endogenous chitin in humans, chitinases are present in the serum of healthy subjects and their levels are increased in a variety of chronic inflammatory conditions. It has been shown that chitotriosidase and structurally related chitinase-like protein-YKL-40 contribute to the pathogenesis of COPD. However, details regarding the relation of their systemic and local airways levels remain unknown.

Objectives

To examine peripheral blood and sputum chitotriosidase and YKL-40 expression in smokers and patients with COPD.

Methods

Forty patients with COPD, 20 healthy smokers and 10 healthy never-smokers were studied. Serum and induced sputum chitotriosidase protein and activity levels, YKL-40 concentrations, and their gene expression in sputum cells and peripheral blood mononuclear cells (PBMC) were evaluated.

Results

Both chitotriosidase protein levels and activity were higher in sputum obtained from COPD subjects compared to healthy never-smokers (P<0.05 and P<0.01, respectively). A similar pattern was observed for PBMC chitotriosidase mRNA expression (P<0.001). YKL-40 serum concentrations were elevated in healthy smokers and COPD subjects compared to healthy never-smokers (P<0.001 and P<0.01, respectively). In sputum, YKL-40 levels were increased in COPD compared to healthy never-smokers (P<0.01). PBMC YKL-40 mRNA expression was increased in COPD and healthy smokers compared to healthy never-smokers (P<0.0001). No associations were found between chitotriosidase or YKL-40 peripheral blood levels and sputum levels.

Conclusions

Our results demonstrate that chitotriosidase and YKL-40 are overexpressed in peripheral blood and airways in both healthy smokers and COPD subjects which may indicate smoking-related activation of macrophages, neutrophils, and epithelial cells.

Identification of Chitinase-3-Like Protein 1 as a Novel Neutrophil Antigenic Target in Crohn's Disease

BACKGROUND AND AIMS

There is an increasing incidence of inflammatory bowel disease [IBD]. Autoimmune responses are involved in the pathophysiology of IBD, but their underlying pathways and target antigens have not yet been fully elucidated.

METHODS

Autoantigenic targets in IBD were identified after separation of whole cell proteins isolated from neutrophils using two-dimensional electrophoresis and matrix assisted laser desorption ionization - time of flight mass spectrometry-based protein identification of the spots that displayed Western blotting signals with anti-neutrophil cytoplasmic antibody-positive sera. The prevalence of IgG, IgA and secretory IgA [sIgA] to chitinase 3-like protein 1 [CHI3L1] was analysed by enzyme-linked immunosorbent assays using recombinant CHI3L1 in 110 patients with Crohn's disease [CD], 95 with ulcerative colitis [UC], 126 with coeliac disease [CeD] and 86 healthy controls [HCs].

RESULTS

The 18-glycosylhydrolase family member CHI3L1 was identified as a neutrophil autoantigenic target. CD patients displayed significantly higher levels of IgG to CHI3L1 than patients with UC and CeD (p < 0.0001, respectively). IgA and sIgA to CHI3L1 was significantly higher in CD than in UC, CeD and HCs [p < 0.0001, respectively]. IgA and sIgA to CHI3L1 demonstrated the highest prevalence in CD [25.5%, 28/110; and 41.8%%, 46/110] compared to HCs [2.3%, 2/86; and 4.7%%, 4/86; p = 0.0015 and p < 0.0001] and are associated with a more complicated progression of CD.

CONCLUSION

CHI3L1 is a novel neutrophil autoantigenic target in CD. IgA and sIgA to CHI3L1 may serve as novel markers for CD and may facilitate the serological diagnosis of IBD.

Concentration of Chondrogenic Soluble Factors in Freshly Harvested Lipoaspirate

BACKGROUND

Cartilage tissue has a limited capacity for healing with the consequence that patients are often treated symptomatically until they become candidates for osteotomy or total joint replacement. Alternative biological therapies, for example, application of platelet-rich plasma and implantation of chondrocytes and mesenchymal stem cells, have emerged as a new treatment modality to repair articular cartilage. In addition, autologous fat transfer is performed for treatment of cartilage defects, example given, in osteoarthrosis, but several questions regarding basic biochemical properties of the transplant remain unanswered. Bone morphogenetic protein 4 (BMP4), matrix metalloproteinase (MMP)-8, cartilage oligomeric matrix protein (COMP), and chitinase-3-like protein 1 (CHI3L1) have been shown to be involved in chondrogenic regeneration and represent potential therapeutic agents for cartilage repair. However, no study regarding naturally occurring levels of these soluble factors in transplanted adipose tissue has yet been performed.

METHODS

To investigate the influence of age, body mass index, donor site, and sex on the concentration of BMP4, MMP-8, COMP, and CHI3L1 in freshly aspirated adipose tissue, their content was measured by means of enzyme-linked immunosorbent assay readings.

RESULTS

There were significant quantities of BMP4, MMP-8, COMP, and CHI3L1 (23.6, 249.9, 298.0, and 540.6 pg/mg, respectively) in the lipoaspirate harvested for transplantation. There was no correlation between the content of soluble factors and the patients' age or body mass index. Furthermore, the sex did not affect the amount of the investigated factors. However, there were significantly lower contents of BMP4, COMP, and CHI3L1 found in lipoaspirates harvested from the abdomen compared with nonabdominal donor sites.

CONCLUSIONS

Naturally occurring differences in the concentrations of the investigated soluble factors will favor certain donor sites for autologous fat transfer in the field of cartilage repair. Thus, increasing knowledge will enable researchers and clinicians to make autologous fat transfer procedures more reliable and efficient for treatment of articular cartilage defects.

Western diet induces endogen oxidative deoxyribonucleic acid damage and infl ammation in Wistar rats

ABSTRACT Objective Nutritional diseases such as metabolic syndrome, cardiovascular disorder, chronic inflammation or even cancer are observed in people who sustain their lifestyle by Western diet due to high calorie intake. The origin of these diseases are the degraded deoxyribonucleic acid structure. In this study, we investigated whether Western diet produced endogenous oxidative deoxyribonucleic acid damage, apoptosis or inflammation. Methods Twenty-eight male Wistar rats, aged 10-12 weeks, were divided into four groups. The rats in control group received the standard diet and the remaining rats were given one of the following three diets for four weeks: a high-fat diet containing 35% fat, a high-sucrose diet containing 69% sucrose and Western diet comprising both two types of diets. After treatment the serum 8-hydroxy-2-deoxyguanosine, poly (adenosine diphosphate ribose) polymerase-1, chitinase-3-like protein 1, soluble urokinase-type plasminogen activator receptor, Fas ligand and cytochrome c levels were measured. Results It was observed no changes in the serum soluble urokinase-type plasminogen activator receptor, Fas ligand and cytochrome c levels whereas a statistically significant increase in the serum 8-hydroxy-2-deoxyguanosine, poly (adenosine diphosphate ribose) polymerase-1 and chitinase-3-like protein 1 levels were found only in rats that were given Western diet. Conclusion The findings show that Western diet produced endogenous oxidative deoxyribonucleic acid damage, which then increased serum poly (adenosine diphosphate ribose) polymerase-1 levels, eventually leading to inflammation.

YKL-40 as a Potential Biomarker and a Possible Target in Therapeutic Strategies of Alzheimer's Disease

Background:

Growing body of evidence suggests that the pathogenesis of Alzheimer’s disease (AD), a progressing neurodegenerative condition, is not limited to the neuronal compartment, but also involves various immunological mechanisms. Insoluble Aβ aggregates in the brain can induce the activation of microglia, resulting in the synthesis of proinflammatory mediators, which further can stimulate astrocytic expression of YKL-40. Therefore, the aim of the current review is to present up-to-date data about the role of YKL-40 as a biomarker of AD as well as the possibility of therapeutic strategies targeting neuroinflammation.

Objective/Methods:

We searched PubMed articles for the terms “YKL-40”, “neurodegeneration”, “neuroinflammation” and “Alzheimer’s disease”, and included papers focusing on this review’s scope.

Results:

Recent studies indicate that CSF concentrations of YKL-40 were significantly higher in AD patients than in cognitively normal individuals and correlated with dementia biomarkers, such as tau proteins and amyloid beta. Determination of YKL-40 CSF concentration may be also helpful in differentiation between types of dementia and in the distinction of patients in the stable phase of MCI from those who progressed to dementia. Moreover, significantly increased levels of YKL-40 mRNA were found in AD brains in comparison with non-demented controls. Additionally, it was suggested that anti-inflammatory treatment might relief the symptoms of AD and slow its progression.

Conclusion:

Based on the recent knowledge, YKL-40 might be useful as a possible biomarker in the diagnosis and prognosis of AD. Modulation of risk factors and targeting of immune mechanisms, including systemic inflammation could lead to future preventive or therapeutic strategies for AD.

Serum YKL-40 as a biomarker for liver fibrosis in chronic hepatitis B patients with normal and mildly elevated ALT

Purpose

YKL-40 is a chitinase-like protein expressed in multiple tissues including liver and is reported as a fibrosis marker. This study aimed to determine whether YKL-40 could serve as a diagnostic marker for the assessment of liver fibrosis in chronic hepatitis B patients with normal and mildly elevated ALT.

Methods

Six hundred and eighty-five patients with chronic hepatitis B infection were enrolled in this study from October 2013 to March 2016. All patients underwent liver biopsy and then staged based on Ishak histological system. Serum YKL-40 levels were measured by Human Magnetic Luminex Assays.

Results

Among chronic hepatitis B patients with normal and mildly elevated ALT, almost more than 30% of patients have significant liver fibrosis. Serum YKL-40 levels increased significantly in parallel with the progression of fibrosis in patients with ALT less than two times the upper limit of normal range (P < 0.0001). Multivariate analysis revealed that serum YKL-40, hyaluronic acid, PLT, and AST were independently associated with significant fibrosis. We established a novel YKL-40-based fibrosis model for patients with ALT less than two times the upper limit of normal range (ULN). YKL-40 model was superior to APRI, FIB-4, Forns’ index, and Hui model for diagnosis of significant fibrosis in patients with ALT < 2ULN, with AUROCs of 0.786 [95% confidence interval (CI) 0.726–0.846] in the training group, 0.831 (95%CI 0.752–0.910) in the validation group and 0.801 (95%CI 0.753–0.849) in the entire cohort.

Conclusion

Serum YKL-40 is a feasible biomarker of liver fibrosis in chronic hepatitis B patients. YKL-40 model was superior to APRI, FIB-4, Forns’ index and Hui model for diagnosis of significant fibrosis in patients with normal and mildly elevated ALT.

Electronic supplementary material

The online version of this article (10.1007/s15010-018-1136-2) contains supplementary material, which is available to authorized users.

Potential suppressive effects of theophylline on human rectal cancer SW480 cells in vitro by inhibiting YKL-40 expression

Chitinase-3-like-1 protein (YKL-40), a member of the mammalian chitinase-like glycoproteins, serves a key role in the pathogenesis of rectal cancer. The present study examined the antitumor effect of theophylline, a pan-chitinase inhibitor, in rectal cancer in vitro and investigated the mechanism by which it acted. SW480 cell lines were treated with varying theophylline concentrations (10^-2, 10^-3, 10^-4 and 10^-5 mol/l). An MTT assay was used to observe cell proliferation and identify the optimal theophylline concentration. Western blotting was used to analyze YKL-40 expression. The cell cycle distribution of SW480 cell lines treated with theophylline was measured by flow cytometry. The angiopoietin-2 expression level was measured by ELISA. The expression levels of YKL-40 were evidently decreased in theophylline-treated SW480 cell lines. The proliferation of SW480 cells was inhibited following theophylline treatment, which was associated with G₁ phase cell cycle arrest and a decrease in the expression of angiopoietin-2. The mechanism of theophylline action may involve the downregulation of YKL-40 expression, arrest of the cell cycle at G₁ phase and inhibition of angiopoietin-2 expression. These results provide a rationale for the potential use of anti-YKL-40 and anti-angiogenic strategies in treating rectal cancer.

Chitin, chitinases, and chitin lectins: Emerging roles in human pathophysiology

Chitin is a simple β-linked repeating sugar polymer prominent in the building block structures of a wide variety of organisms, from the yeast cell wall to the exoskeleton and shells of arthropods and other forms of invertebrate life. It had previously been assumed that vertebrates did not contain chitins. However, chitin and chitinases are now documented to occur in vertebrate tissues. Chitin, chitinases and particularly chitinase-like proteins are involved in important human pathologies, though the mechanisms by which these function is unknown. These chitinase-like proteins bind to chitin and function as chitin lectins in that they bind to chitin but have lost the ability to degrade it. Emphasis is placed on one of the chitinase-like proteins, CHI3L1, that has acquired wide clinical importance. The purpose of this review is to place an array of bewildering observations associated with various human disorders into a framework, particularly the pathologies of the human gastro-intestinal tract. A reasonably cohesive story may eventually emerge.

Angiogenic potential of YKL-40 in the dynamics of tumor niche

A multitude of clinical studies showed the elevation of YKL-40 in subjects with different kinds of tumors. It is predicted that an inherent correlation exists between survivals of cancer patients with total YKL-40 serum levels, making this factor as a potential novel biomarker. However, the crucial role of YKL-40 in the dynamics of cancers, especially angiogenesis, has not yet been completely addressed. In this review, we highlighted the various facets of YKL-40 and its importance in cancer biology as a bio-shuttle in gene therapy.

iTRAQ-based proteomic analysis identifies proteins involved in limb regeneration of swimming crab Portunus trituberculatus

The swimming crab (Portunus trituberculatus) has a striking capacity for limb regeneration, which has drawn the interest of many researchers. In this study, isobaric tag for relative and absolute quantitation (iTRAQ) approach was utilised to investigate protein abundance changes during limb regeneration in this species. A total of 1830 proteins were identified, of which 181 were significantly differentially expressed, with 94 upregulated and 87 downregulated. Our results highlight the complexity of limb regeneration and its regulation through cooperation of various biological processes including cytoskeletal changes, extracellular matrix (ECM) remodelling and ECM-receptor interactions, protein synthesis, signal recognition and transduction, energy production and conversion, and substance transport and metabolism. Additionally, real-time PCR confirmed that mRNA levels of differentially expressed genes were correlated with protein levels. Our results provide a basis for studying the regulatory mechanisms associated with crab limb regeneration.

The YKL-40 protein is a potential biomarker for COPD: a meta-analysis and systematic review

Background

Many studies have found that YKL-40 may play an important pathogenic role in COPD. However, the results of these studies were inconsistent. Therefore, we performed a systematic review and meta-analysis to investigate the role of YKL-40 in COPD.

Methods

We performed a systematic literature search in many database and commercial internet search engines to identify studies involving the role of YKL-40 in patients with COPD. The standardized mean difference (SMD) and Fisher’s Z-value with its 95% confidence interval (CI) were used to investigate the effect sizes.

Results

A total of 15 eligible articles including 16 case–control/cohort groups were included in the meta-analysis. The results indicated that the serum YKL-40 levels in patients with COPD were significantly higher than those in healthy controls (SMD =1.58, 95% CI =0.68–2.49, P=0.001), and it was correlated with lung function (pooled r=−0.32; Z=−0.33; P<0.001). The results of subgroup analysis found that the serum YKL-40 levels were statistically different between the exacerbation group and the stable group in patients with COPD (SMD =1.55, 95% CI =0.81–2.30, P<0.001). Moreover, the results indicated that the sputum YKL-40 levels in patients with COPD were also significantly higher than those in healthy controls (SMD =0.70, 95% CI =0.10–1.30, P=0.022).

Conclusion

The current study suggests that YKL-40 may be implicated in bronchial inflammation and remodeling in COPD and may be considered as a useful biomarker for COPD diagnosis and monitoring.

Pre-Treatment Prediction of Chemoresistance in Second-Line Chemotherapy of Ovarian Carcinoma: Value of Serological Tumor Marker Determination (Tetranectin, YKL-40, CASA, CA 125)

Objective

To examine if the determination of the levels of serological tumor markers at time of relapse had any predictive value for chemoresistance in the second-line treatment of ovarian cancer patients.

Methods

From a registry of consecutive single-institution patients with epithelial ovarian carcinoma pretreated with paclitaxel plus platinum, we selected 82 patients with (a) solid tumor recurrence, and (b) second-line chemotherapy consisting of topotecan (platinum-resistant disease) or paclitaxel plus carboplatin (platinum-sensitive disease). Stored serum samples were analyzed for the biochemical tumor markers tetranectin, YKL-40, CASA (cancer-associated serum antigen), and CA 125. The serum tumor marker levels at time of relapse were correlated with response status at landmark time after 4 cycles of second-line chemotherapy. Univariate and multivariate logistic regression analyses (chemoresistant vs non-chemoresistant disease) were performed.

Results

At landmark time, 26% of patients had progression according to the GCIG (Gynecologic Cancer Intergroup) progression criteria. In univariate logistic regression analysis, the tumor markers tetranectin (OR 0.4; 95% CI: 0.2–0.8; p=0.008), YKL-40 (OR 1.8; 95% CI: 1.0–3.3; p=0.045), and CASA (OR 1.8; 95% CI: 1.2–2.7; p=0.007) had predictive value for second-line chemoresistance, whereas serum CA 125 had no predictive value. In a multivariate logistic regression analysis, serum tetranectin and CASA both had independent predictive value for chemoresistance. The combined determination of tetranectin and CASA had a specificity of 90% with 33% sensitivity for the prediction of chemoresistance (area under the receiver operating characteristic curve = 0.78; 95% CI: 0.66–0.91; p=0.001).

Conclusion

Low serum levels of tetranectin, or high serum levels of CASA or YKL-40, are associated with increased risk of second-line chemoresistance in patients with ovarian cancer.

Galectin-1 from conditioned medium of three-dimensional culture of adipose-derived stem cells accelerates migration and proliferation of human keratinocytes and fibroblasts

Keratinocytes and fibroblasts cells play important roles in the skin-wound healing process and are the cell types activated by trauma. Activated cells participate in epithelialization, granulation, scar tissue formation, wound remodeling, and angiogenesis via a series of cellular activities including migration and proliferation. Previous studies reported that the conditioned medium (CM) of adipose-derived stem cells (ADSCs) stimulated the migration and proliferation of cell types involved in the skin wound healing process; however, these studies only show ADSC-CM effects that were obtained using 2-dimensional (2D) culture. Recently, 3-dimensional (3D) culture has been considered as a more physiologically appropriate system than 2D culture for ADSC cultures; therefore, ADSC-CM was collected from 3D culture (ADSC-CM-3D) and compared with ADSC-CM from 2D culture (ADSC-CM-2D) to investigate the effects on the migration and proliferation of human keratinocytes (HaCaTs) and fibroblasts. The migrations of the HaCaT cells and fibroblasts were significantly higher with ADSC-CM-3D compared with the 2D culture; similarly, the proliferation of HaCaT cells was also highly stimulated by ADSC-CM-3D. Proteomic analyses of the ADSC-CM revealed that collagens and actins were highly expressed in the 3D-culture system. Chitinase 3-like 1 (CHI3L1), tissue inhibitor of metalloproteinases (TIMP), and galectin-1 were specifically expressed only in ADSC-CM-3D. Especially, through antibody neutralization, galectin-1 in ADSC-CM-3D was found to be an important factor for the migration of human keratinocytes. Therefore, these results suggest that ADSC-CM-3D was more effective in the wound healing than ADSC-CM-2D, and galectin-1 in ADSC-CM-3D was could be a promising option for skin-wound healing. Furthermore, the differential expressions of several ADSC-CM proteins between the 2D- and 3D-culture systems may be used as basic information for the development of efficient wound-healing strategies.

Human Chitinases and Chitinase-Like Proteins as Indicators for Inflammation and Cancer

Human Glyco_18 domain-containing proteins constitute a family of chitinases and chitinase-like proteins. Chitotriosidase and AMCase are true enzymes which hydrolyse chitin and have a C-terminal chitin-binding domain. YKL-40, YKL-39, SI-CLP and murine YM1/2 proteins possess solely Glyco_18 domain and do not have the hydrolytic activity. The major sources of Glyco_18 containing proteins are macrophages, neutrophils, epithelial cells, chondrocytes, synovial cells, and cancer cells. Both macrophages and neutrophils use the regulated secretory mechanism for the release of Glyco_18 containing proteins. Glyco_18 containing proteins are established biomarkers for human diseases. Chitotriosidase is overproduced by lipid-laden macrophages and is a major marker for the inherited lysosomal storage Gaucher disease. AMCase and murine lectin YM1 are upregulated in Th2-environment, and enzymatic activity of AMCase contributes to asthma pathogenesis. YKL proteins act as soluble mediators for the cell proliferation and migration, and are also involved in rheumatoid arthritis, inflammatory bowel disease, hepatic fibrosis and cirrhosis. Chitotriosidase and YKL-40 reflect the macrophage activation in atherosclerotic plaques. Serum level of YKL-40 is a diagnostic and prognostic marker for numerous types of solid tumors. YKL-39 is a marker for the activation of chondrocytes and the progression of the osteoarthritis in human. Recently identified SI-CLP is upregulated by Th2 cytokine IL-4 as well as by glucocorticoids. This unique feature of SI-CLP makes it an attractive candidate for the examination of individual sensitivity of patients to glucocorticoid treatment and prediction of side effects of glucocorticoid therapy. Human chitinases and chitinase-like proteins are found in tissues and circulation, and can be detected by non-invasive technologies.

YKL-40 expression in abnormal invasive placenta cases

OBJECTIVE

YKL-40 is a secreted glycoprotein and has been implicated in the proliferation and differentiation of malignant cells, extracellular tissue remodelling, neovascularisation, inhibition of cancer cell apoptosis and stimulation of tumour-associated fibroblasts. The purpose of this study was to evaluate YKL-40 tissue expression in extravillous trophoblast invasion and its possible implication in placenta creta.

METHODS

A total of 35 placenta creta cases and six control cases were included in the study, of which eight cases were placenta accreta, 12 were increta and 15 were percreta. Histological YKL-40 staining was scored in tissue as weak (1), medium (2) and strong (3).

RESULTS

YKL-40 immunoreactivity intensity in the percreta group was significantly higher compared to the increta and accreta groups (2.47±0.74, 1.33±0.49 and 1.37±0.52, respectively; P=0.000). YKL-40 immunoreactivity intensity was positively correlated with creta (r=0.6; P=0.000), depth of invasion (r=0.49; P=0.003) and depth of invasion to full thickness ratio (r=0.58; P=0.000).

CONCLUSION

This study demonstrated that YKL-40 is strongly expressed in placenta percreta and is correlated with extravillous trophoblast invasion. These findings may be informative for understanding the pathophysiology of placenta creta.

New Insights Into the Relationship Between Chitinase-3-Like-1 and Asthma

PURPOSE OF REVIEW

CHI3L1 (also known as YKL-40), a member of "mammalian chitinase-like proteins," is a serum protein lacking enzymatic activity. Although the protein is highly conserved in mammals, a consensus regarding its role in human pathologies is currently lacking. In an attempt to shed light on the many physiological functions of the protein, specifically with regard to asthma, a comprehensive overview of recent studies is provided.

RECENT FINDINGS

In asthma, CHI3L1 is secreted from macrophages and airway epithelial cells through an IL-13 related mechanism. Th2-associated inflammatory responses due to allergen exposure, resulting in airway hyper-responsiveness and smooth muscle contraction, play a role in tissue remodeling. The importance of CHI3L1 in initiation and development of asthma is not limited to its involvement in highly orchestrated events of inflammatory cytokines but further research is needed for further elucidation. Levels of the protein are associated with severity for numerous pathologies, including asthma, suggesting limited specificity as a biomarker.

Circulating Bone-related Markers and YKL-40 Versus HER2 and TOPO2a in Bone Metastatic and Nonmetastatic Breast Cancer: Diagnostic Implications

BACKGROUND

The bone represents one of the most common sites of metastases in breast cancer. The aim of the current study was to evaluate the diagnostic potential of several circulating markers to detect metastasis to bones in patients with breast cancer.

PATIENTS AND METHODS

Receptor activator of Nuclear Factor-kappa β (NF-Kβ) ligand (RANKL), osteoprotegrin (OPG), vitamin D (VIT D), Chitinase-3-like protein 1; also known as YKL-40, topoisomerase IIα (TOPO2a), and human epidermal growth factor receptor 2 (HER2) were measured in blood samples obtained from 122 patients with breast cancer and 25 healthy controls.

RESULTS

All biomarkers were significantly elevated in patients with breast cancer with bone metastasis compared with nonmetastatic patients except YKL-40. RANKL had the highest diagnostic performance for bone metastasis detection with an area under the curve of 97.3, a sensitivity of 85%, and a specificity of 98.6%. Furthermore, logistic regression analysis resulted in a model of RANKL combined with HER2 that had even higher discriminatory power of metastasis to bones than that of RANKL alone. Overall correct classification of the model was 98.9%.

CONCLUSION

We recommend that measuring RANKL together with HER2 can be routinely applied to allow early detection of bone metastases in patients with breast cancer.

Clinical Signifıcance of Serum Ykl-40 (Chitinase-3-Like-1 Protein) as a Biomarker in Melanoma: an Analysis of 112 Turkish Patients

Background: Angiogenesis plays an essential role in tumor growth and serum levels of YKL-40 , a strong angiogenic factor that promotes tumor vessel development, has been found to be elevated in various cancers. We here investigated correlation between melanoma parameters and serum YKL-40 levels, to assess potential diagnostic, prognostic and predictive values. Material and Methods: Data for 112 pathologically confirmed cutaneous melanomas of any stage were examined retrospectively. ELISA assays were used to measure serum YKL-40 in plasma samples. Results: The baseline serum YKL-40 levels were significantly higher in patients than healthy controls (174.88 vs 120.10 ng/mL, p<0.001). However, values did not correlate with clinicopathological parameters, (p>0.05), and furthermore there was no apparent prognostic influence on melanoma survival (HR: 1.568; 95% CI, 0.580-3.051; p=0.838). Conclusion: Serum YKL-40 can be useful for diagnosis of melanoma, but reliability in assessing prognosis is questionable. We believe that efforts should be made to understand the interaction between YKL-40 and the tumor environment, and establish whether it might be the target for treatment of malignancies.

Proteomics Analysis Identifies Orthologs of Human Chitinase-Like Proteins as Inducers of Tube Morphogenesis Defects in Drosophila melanogaster

Elevated levels of human chitinase-like proteins (CLPs) are associated with numerous chronic inflammatory diseases and several cancers, often correlating with poor prognosis. Nevertheless, there is scant knowledge of their function. The CLPs normally mediate immune responses and wound healing and, when upregulated, they can promote disease progression by remodeling tissue, activating signaling cascades, stimulating proliferation and migration, and by regulating adhesion. We identified Imaginal disc growth factors (Idgfs), orthologs of human CLPs CHI3L1, CHI3L2, and OVGP1, in a proteomics analysis designed to discover factors that regulate tube morphogenesis in a Drosophila melanogaster model of tube formation. We implemented a novel approach that uses magnetic beads to isolate a small population of specialized ovarian cells, cells that nonautonomously regulate morphogenesis of epithelial tubes that form and secrete eggshell structures called dorsal appendages (DAs). Differential mass spectrometry analysis of these cells detected elevated levels of four of the six Idgf family members (Idgf1, Idgf2, Idgf4, and Idgf6) in flies mutant for bullwinkle (bwk), which encodes a transcription factor and is a known regulator of DA-tube morphogenesis. We show that, during oogenesis, dysregulation of Idgfs (either gain or loss of function) disrupts the formation of the DA tubes. Previous studies demonstrate roles for Drosophila Idgfs in innate immunity, wound healing, and cell proliferation and motility in cell culture. Here, we identify a novel role for Idgfs in both normal and aberrant tubulogenesis processes.

Alterations in the Salivary Proteome and N-Glycome of Sjögren's Syndrome Patients

We used isobaric mass tagging (iTRAQ) and lectin affinity capture mass spectrometry (MS)-based workflows for global analyses of parotid saliva (PS) and whole saliva (WS) samples obtained from patients diagnosed with primary Sjögren's Syndrome (pSS) who were enrolled in the Sjögren's International Collaborative Clinical Alliance (SICCA) as compared with two control groups. The iTRAQ analyses revealed up- and down-regulation of numerous proteins that could be involved in the disease process (e.g., histones) or attempts to mitigate the ensuing damage (e.g., bactericidal/permeability increasing fold containing family (BPIF) members). An immunoblot approach applied to independent sample sets confirmed the pSS associated up-regulation of β2-microglobulin (in PS) and down-regulation of carbonic anhydrase VI (in WS) and BPIFB2 (in PS). Beyond the proteome, we profiled the N-glycosites of pSS and control samples. They were enriched for glycopeptides using lectins Aleuria aurantia and wheat germ agglutinin, which recognize fucose and sialic acid/N-acetyl glucosamine, respectively. MS analyses showed that pSS is associated with increased N-glycosylation of numerous salivary glycoproteins in PS and WS. The observed alterations of the salivary proteome and N-glycome could be used as pSS biomarkers enabling easier and earlier detection of this syndrome while lending potential new insights into the disease process.

Chitinase 3-like-1 is produced by human Th17 cells and correlates with the level of inflammation in juvenile idiopathic arthritis patients

BACKGROUND

CHI3L1 is a chitinase-like protein without enzymatic activity, produced by activated macrophages, chondrocytes, neutrophils. Recent studies on arthritis, asthma, and inflammatory bowel diseases suggest that chitinases are important in inflammatory processes and tissue remodeling, but their production by human T cells, has never been reported.

METHODS

A microarray analysis of gene expression profile was performed on Th17 and classic Th1 cell clones and CHI3L1 was found among the up-regulated genes on Th17 cells. Different types of helper T cell clones (TCCs) were then evaluated by Real Time PCR (RT-PCR) for CHI3L1 mRNA expression; protein expression was investigated in cell lysates by western blotting and in cultures supernatants by ELISA. ELISA was also used to measure CHI3L1 in the serum and in the synovial fluid (SF) of juvenile idiopathic arthritis (JIA) patients.

RESULTS

At mRNA level CHI3L1 was highly expressed by Th17, Th17/Th1, non classic Th1 and even in Th17/Th2 cell clones, whereas it was virtually absent in CD161- classic Th1 and Th2 TCCs. CHI3L1 was also detected in cell culture supernatants of Th17 and Th17-derived cells but not of classic Th1. Moreover CHI3L1 was higher in the SF than in serum of JIA patients, and it positively correlated with the frequency of Th17 and non-classic Th1 cells in SF. CHI3L1 in SF also positively correlated with the C reactive protein (CRP) serum levels, and with the levels of some proinflammatory cytokines, such as IL-6 and p40, which is the common subunit of IL12 and IL23.

CONCLUSIONS

Here we describe for the first time CHI3L1 production by T cells owing the Th17 family. Moreover the positive correlation found between the frequency of Th17 and Th17-derived cell subsets and CHI3L1 levels in SF of JIA patients, in agreement with the suggested role of these cells in inflammatory process, candidates CHI3L1 as a possible biological target in JIA treatment.

Increased Obesity-Associated Circulating Levels of the Extracellular Matrix Proteins Osteopontin, Chitinase-3 Like-1 and Tenascin C Are Associated with Colon Cancer

BACKGROUND

Excess adipose tissue represents a major risk factor for the development of colon cancer with inflammation and extracellular matrix (ECM) remodeling being proposed as plausible mechanisms. The aim of this study was to investigate whether obesity can influence circulating levels of inflammation-related extracellular matrix proteins in patients with colon cancer (CC), promoting a microenvironment favorable for tumor growth.

METHODS

Serum samples obtained from 79 subjects [26 lean (LN) and 53 obese (OB)] were used in the study. Enrolled subjects were further subclassified according to the established diagnostic protocol for CC (44 without CC and 35 with CC). Anthropometric measurements as well as circulating metabolites and hormones were determined. Circulating concentrations of the ECM proteins osteopontin (OPN), chitinase-3-like protein 1 (YKL-40), tenascin C (TNC) and lipocalin-2 (LCN-2) were determined by ELISA.

RESULTS

Significant differences in circulating OPN, YKL-40 and TNC concentrations between the experimental groups were observed, being significantly increased due to obesity (P<0.01) and colon cancer (P<0.05). LCN-2 levels were affected by obesity (P<0.05), but no differences were detected regarding the presence or not of CC. A positive association (P<0.05) with different inflammatory markers was also detected.

CONCLUSIONS

To our knowledge, we herein show for the first time that obese patients with CC exhibit increased circulating levels of OPN, YKL-40 and TNC providing further evidence for the influence of obesity on CC development via ECM proteins, representing promising diagnostic biomarkers or target molecules for therapeutics.

The C-terminal region of OVGP1 remodels the zona pellucida and modifies fertility parameters

OVGP1 is the major non-serum glycoprotein in the oviduct fluid at the time of fertilization and early embryo development. Its activity differs among species. Here, we show that the C-terminal region of recombinant OVGP1 regulates its binding to the extracellular zona pellucida and affects its activity during fertilization. While porcine OVGP1 penetrates two-thirds of the thickness of the zona pellucida, shorter OVGP1 glycoproteins, including rabbit OVGP1, are restricted to the outer one-third of the zona matrix. Deletion of the C-terminal region reduces the ability of the glycoprotein to penetrate through the zona pellucida and prevents OVGP1 endocytosis. This affects the structure of the zona matrix and increases its resistance to protease digestion. However, only full-length porcine OVGP1 is able to increase the efficiency rate of in vitro fertilization. Thus, our findings document that the presence or absence of conserved regions in the C-terminus of OVGP1 modify its association with the zona pellucida that affects matrix structure and renders the zona matrix permissive to sperm penetration and OVGP1 endocytosis into the egg.

Comparative proteomics illustrates the complexity of drought resistance mechanisms in two wheat (Triticum aestivum L.) cultivars under dehydration and rehydration

BACKGROUND

Drought stress is one of the most adverse environmental constraints to plant growth and productivity. Comparative proteomics of drought-tolerant and sensitive wheat genotypes is a strategy to understand the complexity of molecular mechanism of wheat in response to drought. This study attempted to extend findings regarding the potential proteomic dynamics in wheat under drought stress and to enrich the research content of drought tolerance mechanism.

RESULTS

A comparative proteomics approach was applied to analyze proteome change of Xihan No. 2 (a drought-tolerant cultivar) and Longchun 23 (a drought-sensitive cultivar) subjected to a range of dehydration treatments (18 h, 24 h and 48 h) and rehydration treatment (R24 h) using 2-DE, respectively. Quantitative image analysis showed a total of 172 protein spots in Xihan No. 2 and 215 spots from Longchun 23 with their abundance significantly altered (p < 0.05) more than 2.5-fold. Out of these spots, a total of 84 and 64 differentially abundant proteins were identified by MALDI-TOF/TOF MS in Xihan No. 2 and Longchun 23, respectively. Most of these identified proteins were involved in metabolism, photosynthesis, defence and protein translation/processing/degradation in both two cultivars. In addition, the proteins involved in redox homeostasis, energy, transcription, cellular structure, signalling and transport were also identified. Furthermore, the comparative analysis of drought-responsive proteome allowed for the general elucidation of the major mechanisms associated with differential responses to drought of both two cultivars. These cellular processes work more cooperatively to re-establish homeostasis in Xihan No. 2 than Longchun 23. The resistance mechanisms of Xihan No. 2 mainly included changes in the metabolism of carbohydrates and amino acids as well as in the activation of more antioxidation and defense systems and in the levels of proteins involved in ATP synthesis and protein degradation/refolding.

CONCLUSIONS

This study revealed that the levels of a number of proteins involved in various cellular processes were affected by drought stress in two wheat cultivars with different drought tolerance. The results showed that there exist specific responses to drought in Xihan No. 2 and Longchun 23. The proposed hypothetical model would explain the interaction of these identified proteins that are associated with drought-responses in two cultivars, and help in developing strategies to improve drought tolerance in wheat.

European Crohn's and Colitis Organisation Topical Review on Prediction, Diagnosis and Management of Fibrostenosing Crohn's Disease

This ECCO topical review of the European Crohn's and Colitis Organisation [ECCO] focused on prediction, diagnosis, and management of fibrostenosing Crohn's disease [CD]. The objective was to achieve evidence-supported, expert consensus that provides guidance for clinical practice.

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 specific 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, inflammation, 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 inflammatory diseases.

Glycoprotein YKL-40: a novel biomarker of chronic graft-vs-host disease activity and severity?

AIM

To investigate whether increased YKL-40 levels positively correlate with graft-vs-host disease (cGVHD) activity and severity and if YKL-40 could serve as a disease biomarker.

METHODS

This case-control study was conducted at the University Hospital Centre Zagreb from July 2013 to October 2015. 56 patients treated with hematopoietic stem cell transplantation (HSCT) were included: 35 patients with cGVHD and 21 without cGVHD. There was no difference between groups in age, sex, median time from transplant to study enrollment, intensity of conditioning, type of donor, or source of stem cells. Blood samples were collected at study enrollment and YKL-40 levels were measured with ELISA. Disease activity was estimated using Clinician's Impression of Activity and Intensity of Immunosuppression scales and disease severity using Global National Institutes of Health (NIH) score.

RESULTS

YKL-40 levels were significantly higher in cGVHD patients than in controls (P=0.003). The difference remained significant when patients with myelofibrosis were excluded from the analysis (P=0.017). YKL-40 level significantly positively correlated with disease severity (P<0.001; correlation coefficient 0.455), and activity estimated using Clinician's Impression of Activity (P=0.016; correlation coefficient 0.412) but not using Intensity of Immunosuppression (P=0.085; correlation coefficient 0.296).

CONCLUSION

YKL-40 could be considered a biomarker of cGVHD severity and activity. However, validation in a larger group of patients is warranted, as well as longitudinal testing of YKL-40 levels in patients at risk of developing cGVHD.

Role of inflammatory marker YKL-40 in the diagnosis, prognosis and cause of cardiovascular and liver diseases

This review summarizes present evidence for the role of YKL-40 in the diagnosis, prognosis and cause of cardiovascular and alcoholic liver disease. The question of whether YKL-40 is merely a marker or a causal factor in the development of cardiovascular and liver disease is addressed, with emphasis on the Mendelian randomization design. The Mendelian randomization approach uses genetic variants associated with lifelong high plasma YKL-40 levels that are largely unconfounded and not prone to reverse causation. Thus, the approach mimics a controlled double-blind randomized trial, but it uses genetic variants rather than a drug and placebo, and like a blinded trial, it allows inference about causality. Moreover, the review also covers background on the molecular biology and functions of YKL-40, YKL-40 levels in healthy individuals and reference range, and the role of YKL-40 as a biomarker of cardiovascular and alcoholic liver disease. YKL-40 is a plasma protein named after its three N-terminal amino acids, Y (tyrosine), K (lysine) and L (leucine), and its molecular weight of 40 kDa. It is produced by local inflammatory cells in inflamed tissues, such as lipid-laden macrophages inside the vessel wall and perhaps also hepatic stellate cells. Observational studies show that plasma YKL-40 levels are elevated in patients with cardiovascular and liver disease and are associated with disease severity and prognosis. Furthermore, elevated plasma YKL-40 levels in apparently healthy individuals are associated with a 2-fold increased risk of future ischemic stroke and venous thromboembolism, but not with myocardial infarction, suggesting that YKL-40 could play a role in the formation of embolisms rather than atherosclerosis per se. Further, elevated YKL-40 levels combined with excessive alcohol consumption are associated with 10-years risk of alcoholic liver cirrhosis of up to 7%, suggesting that YKL-40 can be used as a strong noninvasive marker of predicting alcoholic liver cirrhosis. Importantly, in Mendelian randomization studies, genetically elevated plasma YKL-40 levels were not associated with risk of cardiovascular and alcoholic liver disease, thus suggesting that plasma YKL-40 does not play a causal role in the development of these diseases. Despite this, plasma YKL-40 levels may play a role in disease progression after diagnosis, and inhibition of YKL-40 activity might be a novel therapy in some cardiovascular and liver diseases.

Chitinase 3 Like-1: An Emerging Molecule Involved in Diabetes and Diabetic Complications

Chitinase 3 like-1 (CHI3L1) is a chitinase-like protein member of family 18 chitinases, expressed in innate immune cells and involved in endothelial dysfunction and tissue remodelling. Since CHI3L1 is highly expressed in a variety of inflammatory diseases of infectious and non-infectious aetiology, it is recognised as a non-invasive prognostic biomarker for inflammation. A variety of studies revealing the increase in CHI3L1 levels in obesity, insulin resistance and in pathological conditions, such as atherosclerosis, coronary artery disease, acute ischaemic stroke, nephropathy, diabetic retinopathy and osteolytic processes, have suggested that CHI3L1 may also play a critical role in the evolution and complication of diabetes mellitus (DM). In this review we highlight the impact of CHI3L1 expression in DM and its contribution to the complication of this disease.

YKL-40 expression in chronic obstructive pulmonary disease: relation to acute exacerbations and airway remodeling

BACKGROUND

Recent studies suggest that YKL-40, also called chitinase-3-like-1 protein, has been implicated in the pathogenesis of various inflammatory diseases. It is currently unknown, however, whether YKL-40 plays a role in acute exacerbations of chronic obstructive pulmonary disease (AECOPD) and airway remodeling.

METHODS

We evaluated serum YKL-40 levels in patients with AECOPD (n = 37) and stable COPD (n = 44), as well as in controls (n = 47). The association between YKL-40 expression and airway remodeling was analyzed. The effects of YKL-40 on collagen synthesis of primary human lung fibroblasts were also evaluated.

RESULTS

Serum YKL-40 levels were elevated at AECOPD onset as compared to stable disease (median [interquartile range], 78.6 [52.3-122.2] ng/ml versus 46.7 [31.2-75.5] ng/ml; p = 0.0005). The ideal cutoff point for distinguishing patients with AECOPD from those with stable COPD was 64.7 ng/ml (AUC: 0.71; 95%CI: 0.596 to 0.823). YKL-40 expression correlated with airflow obstruction, C-reactive protein, and collagen deposition. Stimulation with YKL-40 promoted collagen production in lung fibroblasts through ERK- and p38-dependent mechanisms.

CONCLUSIONS

YKL-40 expression is up-regulated in patients with COPD and correlates with exacerbation attacks and may contribute to airway remodeling by acting on lung fibroblasts. The current data may provide insight into the underlying pathogenesis of COPD, in which YKL-40 has an important pathogenic role.

TRIAL REGISTRATION

ChiCTR-OCC-13003567.

Differential Roles of M1 and M2 Microglia in Neurodegenerative Diseases

One of the most striking hallmarks shared by various neurodegenerative diseases, including Parkinson's disease, Alzheimer's disease (AD), and amyotrophic lateral sclerosis, is microglia-mediated neuroinflammation. Increasing evidence indicates that microglial activation in the central nervous system is heterogeneous, which can be categorized into two opposite types: M1 phenotype and M2 phenotype. Depending on the phenotypes activated, microglia can produce either cytotoxic or neuroprotective effects. In this review, we focus on the potential role of M1 and M2 microglia and the dynamic changes of M1/M2 phenotypes that are critically associated with the neurodegenerative diseases. Generally, M1 microglia predominate at the injury site at the end stage of disease, when the immunoresolution and repair process of M2 microglia are dampened. This phenotype transformation is very complicated in AD due to the phagocytosis of regionally distributed β-amyloid (Aβ) plaque and tangles that are released into the extracellular space. The endogenous stimuli including aggregated α-synuclein, mutated superoxide dismutase, Aβ, and tau oligomers exist in the milieu that may persistently activate M1 pro-inflammatory responses and finally lead to irreversible neuron loss. The changes of microglial phenotypes depend on the disease stages and severity; mastering the stage-specific switching of M1/M2 phenotypes within appropriate time windows may provide better therapeutic benefit.

YKL-40/chitinase-3-like protein 1 is associated with poor prognosis and promotes cell growth and migration of cholangiocarcinoma

YKL-40, a chitinase-like glycoprotein, is expressed at a high level in cancer patients. Its exact function is unknown and is the subject of current investigation. Here, we report the correlation of plasma YKL-40 levels with clinicopathological features of cholangiocarcinoma (CCA), a lethal bile duct cancer, particularly prevalent in Northeastern Thailand. Statistical analysis of plasma YKL-40 concentrations in 57 CCA patients and 41 normal healthy subjects gave a median value of 169.5 ng/mL for CCA patients compared with 46.9 ng/mL for the control subjects (P < 0.0001). There was no significant association of plasma YKL-40 levels with patient age, tumor grade, or histology type. However, Kaplan-Meier analysis suggested that the elevated plasma YKL-40 level was particularly associated with short survival in CCA patients (P = 0.038). Immunohistochemical examination of 34 CCA tissues revealed low expression of YKL-40 in CCA cells, but high expression in adjacent intratumoral stroma, liver, and connective tissues. Univariate analysis showed significant association of the intratumoral YKL-40 expression in CCA tissues with the non-papillary type CCA. Addition of rYKL-40 in the culture medium and transient expression of YKL-40 in CCA cell lines were shown to promote the growth and migration of the tumor cells, and that YKL-40 interacted with a cell-surface receptor involved in the Akt/Erk-mediated pathway. In conclusion, our results support the proposal of YKL-40 as a new candidate prognostic biomarker for cancer diseases.

Chitinases and immunity: Ancestral molecules with new functions

Chitinases belonging to 18 glycosyl hydrolase family is an ancient gene family that is widely expressed from prokaryotes to eukaryotes. In humans, despite the absence of endogenous chitin, a number of Chitinases and Chitinase-like Proteins (C/CLPs) have been identified. Chitinases with enzymatic activity have a chitin binding domain containing six cysteine residues responsible for their binding to chitin. In contrast, CLPs do not contain such typical chitin-binding domains, but still can bind to chitin with high affinity. Molecular phylogenetic analyses suggest that active Chitinases result from an early gene duplication event. Further duplication events, followed by mutations leading to loss of chitinase activity, allowed evolution of the chi-lectins. For the majority of the mammalian chitinases the last decades have witnessed the appearance of a substantial number of studies describing their expression differentially regulated during more specific immunologic activities. It is becoming increasingly clear that their function is not exclusive to catalyse the hydrolysis of chitin producing pathogens, but include crucial role in bacterial infections and inflammatory diseases. Here we provide an overview of all family members to shed light on the mechanisms and molecular interactions of Chitinases and CLPs in relation to immune response regulation, in order to delineate their future utilization as diagnostic and prognostic markers for numerous diseases.

Serum YKL-40 as a Marker of Left Atrial Fibrosis Assessed by Delayed Enhancement MRI in Lone Atrial Fibrillation

BACKGROUND

Assessment of the left atrial (LA) fibrosis by using delayed-enhanced magnetic resonance imaging (DE-MRI) in atrial fibrillation (AF) patients is a pioneering noninvasive method. Serum YKL-40 is a novel marker for inflammation and known to play a role in ongoing tissue fibrosis. However, its role in LA fibrosis is unclear. We aimed to investigate the association of serum YKL-40 with the presence and extent of LA fibrosis.

METHODS

A total of 50 patients with lone paroxysmal AF (62% male; age: 47.2 ± 7.0 years) underwent cardiac DE-MRI according to study protocol. Cardiac DE-MRI at 1.5 Tesla scanner was used to quantify LA fibrosis. Serum YKL-40 levels and clinical and echocardiographic data were recorded in all participants.

RESULTS

DE-MRI revealed any degree of LA fibrosis in 31 (62%) patients. Median serum YKL-40 was significantly higher (P = 0.008) and left venticular ejection fraction was lower (P = 0.047) in patients with LA fibrosis as compared to patients without LA fibrosis. Extent of LA fibrosis was significantly correlated with age, duration of AF history, serum C-reactive protein, and serum YKL-40 levels. Only log (YKL-40) level was found as independent predictor for the presence of LA fibrosis (odds ratio: 1.626, P = 0.022). Multivariate linear regression analysis pointed out that duration of AF history (β = 0.330, P = 0.003) and serum log (YKL-40) levels (β = 0.546, P < 0.001) were significantly and independently associated with the extent of LA fibrosis.

CONCLUSION

Higher levels of serum YKL-40 are associated with the presence and more extensive LA fibrosis in patients with lone AF. As a marker of inflammation, serum YKL-40 may also be used as an indicator for the degree of LA fibrosis.

The Role of CHI3L1 (Chitinase-3-Like-1) in the Pathogenesis of Infections in Burns in a Mouse Model

In severe burn injury the unique setting of a depleted, dysfunctional immune system along with a loss of barrier function commonly results in opportunistic infections that eventually proof fatal. Unfortunately, the dynamic sequence of bacterial contamination, colonization and eventually septic invasion with bacteria such as Pseudomonas species is still poorly understood although a limiting factor in clinical decision making. Increasing evidence supports the notion that inhibition of bacterial translocation into the wound site may be an effective alternative to prevent infection. In this context we investigated the role of the mammalian Chitinase-3-Like-1 (CHI3L1) non-enyzmatic protein predominately expressed on epithelial as well as innate immune cells as a potential bacterial-translocation-mediating factor. We show a strong trend that a modulation of chitinase expression is likely to be effective in reducing mortality rates in a mouse model of burn injury with superinfection with the opportunistic PA14 Pseudomonas strain, thus demonstrating possible clinical leverage.

Increased CCL17 serum levels are associated with improved survival in advanced melanoma

BACKGROUND

Prognostic factors of melanoma patients with distant metastases remain poorly established. This study aimed to compare the prognostic impact of putative serum biomarkers, namely S100B, YKL-40 or CCL17, in stage IV melanoma patients.

PATIENTS AND METHODS

Serum concentrations were analyzed by ELISA. Disease-specific survival of 80 patients according to S100B, YKL-40 or CCL17 and clinical factors were calculated by univariate Kaplan-Meier survival and multivariate analysis.

RESULTS

Low serum levels of S100B, high concentrations of CCL17 and female gender correlated with improved survival. A trend for favorable prognosis was observed for the M categories M1a/b versus M1c according to the AJCC classification. No correlation with survival was evident for YKL-40 serum levels and age. In multivariate analysis, S100B (HR 2.1; p = 0.005) and CCL17 (HR 1.8; p = 0.029) had independent prognostic impact. Patients with a combination of normal S100B and high CCL17 had a high chance for long-term survival, which was 43 % after 3 years.

CONCLUSION

Serum levels of CCL17 and S100B represent independent prognostic markers for melanoma patients with distant metastases. These biomarkers were more powerful than the M category according to the AJCC classification to indicate overall survival. CCL17 represents a promising biomarker upon immune checkpoint blockade in melanoma.