gp38k (CHI3L1) is a novel adhesion and migration factor for vascular cells

The subventricular zone structure, function and implications for neurological disease

The subventricular zone (SVZ) is a region surrounding the lateral ventricles that contains neural stem cells and neural progenitor cells, which can proliferate and differentiate into various neural and glial cells. SVZ cells play important roles in neurological diseases like neurodegeneration, neural injury, and glioblastoma multiforme. Investigating the anatomy, structure, composition, physiology, disease associations, and related mechanisms of SVZ is significant for neural stem cell therapy and treatment/prevention of neurological disorders. However, challenges remain regarding the mechanisms regulating SVZ cell proliferation, differentiation, and migration, delivering cells to damaged areas, and immune responses. In-depth studies of SVZ functions and related therapeutic developments may provide new insights and approaches for treating brain injuries and degenerative diseases, as well as a scientific basis for neural stem cell therapy. This review summarizes research findings on SVZ and neurological diseases to provide references for relevant therapies.

Mechanistic studies on the role of CHI3L1 in eosinophilic inflammation in chronic sinusitis

More than 10% of adults suffer from chronic rhinosinusitis (CRS), a chronic inflammatory condition that lowers quality of life, reduces productivity, and shortens work hours. Every year, more than 1 million surgeries are performed worldwide as a result of CRS. In recent years, targeted therapy for CRS has become a hotspot of research at home and abroad and has made significant progress, but CRS still has a high recurrence rate. Therefore CRS urgently needs precise targeted therapy. In the pathological process of CRS, the involvement of eosinophils is an important inflammatory mechanism. And excessive aggregation of eosinophils often leads to severe inflammatory responses. Studies have shown that chitinase 3-like protein 1 (CHI3L1) plays a key role in the activation and migration of eosinophils. This review will combine the latest research results to analyse in detail the biological properties of CHI3L1, its expression pattern in CRS, and the possible mechanisms by which it affects eosinophil aggregation by regulating immune responses and inflammatory processes, which will provide insights into the key role of CHI3L1 in the pathological process of CRS and offer a new target for the treatment of CRS.

Circulating YKL-40 levels but not CHI3L1 or TRIB1 gene variants predict long-term outcomes in patients with angiographically confirmed multivessel coronary artery disease

YKL-40 is significantly associated with the prevalence and severity of coronary artery disease (CAD). YKL-40 levels are significantly associated with variations in the CHI3L1 and TRIB1 genes. We investigated candidate genes for YKL-40 levels and evaluated the prognostic value of this biomarker and corresponding variants for long-term outcomes in patients with CAD. We included 4664 and 521 participants from the Taiwan Biobank (TWB) and CAD cohorts, respectively. Candidate variants for circulating YKL-40 levels were investigated using genome-wide association study (GWAS) data from the TWB cohort, and the results were validated in the CAD cohort. The primary endpoint was all-cause mortality. The secondary endpoint was major adverse cardiac events (MACEs), which included the composite endpoints of all-cause mortality, nonfatal acute coronary syndrome, hospitalization for heart failure, and nonfatal stroke. According to the GWAS data from the TWB cohort, three CHI3L1 variants (rs4950928, rs10399931, and rs872129) and one TRIB1 variant (rs6982502) were independently associated with YKL-40 levels. These findings were validated in the CAD cohort. The combined CHI3L1 and TRIB1 weighted genetic risk scores (WGRSs) were not associated with the long-term outcomes (median follow-up period of 3.7 years) in patients with CAD. Conversely, patients with YKL-40 levels in the upper tertile had the highest rates of all-cause mortality and MACEs (log-rank p = 9.58 × 10-8 for all-cause mortality and 1.34 × 10-7 for MACEs). Furthermore, YKL-40 levels predicted poor clinical outcomes only in patients with multivessel CAD (log-rank p = 3.0 × 10-6 for all-cause mortality and 1.10 × 10-5 for MACEs) and not in patients with single-vessel CAD. This study revealed that YKL-40 levels but not the combined CHI3L1 and TRIB1 WGRSs were found to be independent predictors of poor clinical outcomes in patients with multivessel CAD.

Chitinase 3-Like 1 and C-X-C motif chemokine ligand 5 proteins and the hair cycle

Dermal papilla cells (DPCs) exhibit self-recovery ability, which may be involved in hair growth. Therefore, we tested whether DPCs subjected to temporary growth-inhibiting stress (testosterone, 17β-estradiol, mitomycin C, or undernutrition) treatments exhibit self-recovery behavior that can activate hair follicle growth, and examined the changes in cell proliferation capacity and gene expression. Related proteins were identified and their relationships with the hair cycle was examined using a mouse model. Recovery-period DPCs (i.e., from day 3 after loading) were subjected to microarray analysis to detect genetic variations common to each stress treatment. Co-culture of recovery-period DPCs and outer root sheath cells (ORSCs) confirmed the promotion of ORSC proliferation, suggesting that the activation of hair follicle growth is promoted via signal transduction. Chitinase 3-like 1 (CHI3L1) and C-X-C motif chemokine 5 (CXCL5) exhibited ORSC proliferation-promoting effects. Measurement of protein content in the skin during each phase of the hair cycle in mice revealed that CHI3L1 and CXCL5 secretion increased immediately after anagen transition. In a hair-loss mouse model treated with testosterone or 17β-estradiol, CHI3L1 and CXCL5 secretion was lower in treated telogen skin than in untreated skin. Our results suggest that CHI3L1 and CXCL5 secreted by recovery-state DPCs promote hair growth.

Serum YKL-40 and Serum Krebs von den Lungen-6 as Potential Predictive Biomarkers for Rheumatoid Arthritis-Associated Interstitial Lung Disease

BACKGROUND

Interstitial lung disease (ILD) is a common pulmonary manifestation of rheumatoid arthritis (RA) and is associated with a poor prognosis. However, the role of blood biomarkers in RA-associated interstitial lung disease (RA-ILD) is ill-defined. We aim to evaluate the role of YKL-40 and Krebs von den Lungen-6 (KL-6) in the diagnosis and severity evaluation of RA-ILD.

METHODS

45 RA-non-ILD patients and 38 RA-ILD patients were included. The clinical data and the levels of YKL-40 and KL-6 were measured and collected for all patients. The risk factors for RA-ILD were analyzed and their correlation with relevant indicators and predictive value for RA-ILD was explored.

RESULTS

The levels of YKL-40 and KL-6 in RA-ILD patients were higher than RA-non-ILD patients (p < .001). Both YKL-40 and KL-6 were correlated with the incidence of RA-ILD. The predictive power of combined KL-6 and YKL-40 for the presence of ILD was 0.789, with a sensitivity and specificity at 73.7% and 73.3%, respectively. In RA-ILD patients, both YKL-40 and KL-6 were positively correlated with the Scleroderma Lung Study (SLS) I score and negatively correlated with pulmonary function.

CONCLUSIONS

KL-6 and YKL-40 might be a useful biomarker in the diagnosis and severity evaluation of RA-ILD.

New markers in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), a global healthcare and socioeconomic burden, is a multifaceted respiratory disorder that results in substantial decline in health status and life quality. Acute exacerbations of the disease contribute significantly to increased morbidity and mortality. Consequently, the identification of reliable and effective biomarkers for rapid diagnosis, prediction, and prognosis of exacerbations is imperative. In addition, biomarkers play a crucial role in monitoring responses to therapeutic interventions and exploring innovative treatment strategies. Although established markers such as CRP, fibrinogen and neutrophil count are routinely used, a universal marker is lacking. Fortunately, an increasing number of studies based on next generation analytics have explored potential biomarkers in COPD. Here we review those advances and the need for standardized validation studies in the appropriate clinical setting.

Evolutionary insights into sequence modifications governing chitin recognition and chitinase inactivity in YKL-40 (HC-gp39, CHI3L1)

YKL-40, also known as human cartilage glycoprotein-39 (HC-gp39) or CHI3L1, shares structural similarities with chitotriosidase (CHIT1), an active chitinase, but lacks chitinase activity. Despite being a biomarker for inflammatory disorders and cancer, the reasons for YKL-40's inert chitinase function have remained elusive. This study reveals that the loss of chitinase activity in YKL-40 has risen from multiple sequence modifications influencing its chitin affinity. Contrary to the common belief associating the lack of chitinase activity with amino acid substitutions in the catalytic motif, attempts to activate YKL-40 by creating two amino acid mutations in the catalytic motif (MT-YKL-40) proved ineffective. Subsequent exploration that included creating chimeras of MT-YKL-40 and CHIT1 catalytic domains (CatDs) identified key exons responsible for YKL-40 inactivation. Introducing YKL-40 exons 3, 6, or 8 into CHIT1 CatD resulted in chitinase inactivation. Conversely, incorporating CHIT1 exons 3, 6, and 8 into MT-YKL-40 led to its activation. Our recombinant proteins exhibited properly formed disulfide bonds, affirming a defined structure in active molecules. Biochemical and evolutionary analysis indicated that the reduced chitinase activity of MT-YKL-40 correlates with specific amino acids in exon 3. M61I and T69W substitutions in CHIT1 CatD diminished chitinase activity and increased chitin binding. Conversely, substituting I61 with M and W69 with T in MT-YKL-40 triggered chitinase activity while reducing the chitin-binding activity. Thus, W69 plays a crucial role in a unique subsite within YKL-40. These findings emphasize that YKL-40, though retaining the structural framework of a mammalian chitinase, has evolved to recognize chitin while surrendering chitinase activity.

IL13Rα2 as a crucial receptor for Chi3l1 in osteoclast differentiation and bone resorption through the MAPK/AKT pathway

BACKGROUND

Previous research has revealed that the 18 glycoside hydrolase gene family (GH18) member Chitinase 3-like 1 (Chi3l1) can regulate osteoclast differentiation and bone resorption. However, its downstream receptors and molecular mechanisms during osteoclastogenesis have yet to be elucidated.

METHODS

Initially, we conducted a comprehensive investigation to evaluate the effects of recombinant Chi3l1 protein or Chi3l1 siRNA on osteoclast differentiation and the RANKL-induced MAPK/AKT signaling pathways. Moreover, we used immunofluorescence and immunoprecipitation assays to identify IL13Rα2 as the downstream receptor of Chi3l1. Subsequently, we investigated the impact of IL13Rα2 recombinant protein or IL13Rα2-siRNA on osteoclast differentiation and the associated signaling pathways. Finally, we performed in vivo experiments to examine the effect of recombinant IL13Rα2 protein in an LPS-induced mouse model of cranial osteolysis.

RESULTS

Our findings highlight that the administration of recombinant Chi3l1 protein increased the formation of osteoclasts and bolstered the expression of several osteoclast-specific genes (TRAP, NFATC1, CTR, CTSK, V-ATPase d2, and Dc-STAMP). Additionally, Chi3l1 significantly promoted the RANKL-induced MAPK (ERK/P38/JNK) and AKT pathway activation, whereas Chi3l1 silencing inhibited this process. Next, using immunofluorescence and co-immunoprecipitation assays, we identified IL13Rα2 as the binding partner of Chi3l1 during osteoclastogenesis. IL13Rα2 recombinant protein or IL13Rα2-siRNA also inhibited osteoclast differentiation, and IL13Rα2-siRNA attenuated the RANKL-induced activation of the MAPK (ERK/P38/JNK) and AKT pathways, similar to the effects observed upon silencing of Chi3l1. Moreover, the promoting effect of recombinant Chi3l1 protein on osteoclastogenesis and the activation of the MAPK and AKT pathways was reversed by IL13Rα2 siRNA. Finally, recombinant LI13Rα2 protein significantly attenuated the LPS-induced cranial osteolysis and the number of osteoclasts in vivo.

CONCLUSIONS

Our findings suggested that IL13Rα2 served as a crucial receptor for Chi3l1, enhancing RANKL-induced MAPK and AKT activation to promote osteoclast differentiation. These findings provide valuable insights into the molecular mechanisms of Chi3l1 in osteoclastogenesis, with potential therapeutic implications for osteoclast-related diseases. Video Abstract.

[YKL-40 Promotes the Expression of Inflammatory Factors in Type Ⅱ Alveolar Epithelial Cell Model of A549 Cell Line]

Objective

YKL-40, also known as chitinase-3-like-1 (CHI3L1), is a human cartilage glycoprotein-39, with its N-terminus consisting of tyrosine (Y), lysine (K), and leucine (L), hence the name YKL-40. In this study, we explored whether YKL-40 could promote the expression of inflammatory factors in type Ⅱ alveolar epithelial cells.

Methods

A549 cells were cultured in vitro with interleukin (IL)-1β (20 ng/mL), IL-6 (20 ng/mL), tumor necrosis factor-alpha (TNF-α) (20 ng/mL), and interferon-gamma (IFN-γ) (20 ng/mL). The expression of YKL-40 transcription was determined by RT-qPCR. A549 cells were cultured with IL-1β at 5, 10, and 20 ng/mL and the expression of YKL-40 protein was determined by Western blot. A549 cells were cultured with recombinant YKL-40 protein at 0, 100, 500, and 1 000 ng/mL and the expression levels of IL-6 and IL-8 were measured by RT-qPCR. Three pairs of small interfering RNAs targeting YKL-40 (si- YKL-40-1/2/3) and the negative control (NC) were designed and used to transfect A549 cells, respectively, and the expression of YKL-40 was determined by RT-qPCR and Western blot. si- YKL-40-3 was screened out for subsequent experiments. In A549 cells, si- YKL-40-3 and si-NC were transfected and, then, IL-1β (20 ng/mL) was added in for culturing. The expression of YKL-40, IL-6, and IL-8 was determined by RT-qPCR and the expression of multiple factors in the supernatant was measured with the QAH-INF-1 kit.

Results

RT-qPCR results showed that IL-1β could up-regulate YKL-40 protein transcription level compared with that of the control group and the difference was statistically significant ( P<0.01), but IL-6, TNF-α, and IFN-γ could not up-regulate YKL-40 protein transcription level. Western blot results showed that IL-1β (20 ng/mL) could significantly promote the expression of YKL-40 and, compared with that of the control group, the differences showed by groups treated with different concentrations of IL-1β were all statistical significant ( P<0.01). After adding human recombinant YKL-40 protein to A549 cells, the results showed that the expression of inflammatory factors IL-6 and IL-8 was significantly increased and the difference was statistically significant compared with that of the control group ( P<0.05). After the expression of YKL-40 was decreased by si- YKL-40-3 transfection, the expression of IL-6 ( P<0.05), IL-8 ( P<0.05), and other inflammatory factors was inhibited compared with that of the control group.

Conclusion

YKL-40 can promote the expression and secretion of IL-6, IL-8, and other acute inflammatory factors in A549 cell line, a type Ⅱ alveolar epithelial cell model, thus aggravating the inflammatory response. Targeted inhibition of YKL-40 expression may effectively inhibit inflammatory response.

E-cigarette exposure augments murine abdominal aortic aneurysm development: role of Chil1

AIMS

Abdominal aortic aneurysm (AAA) is a common cardiovascular disease with a strong correlation to smoking, although underlying mechanisms have been minimally explored. Electronic cigarettes (e-cigs) have gained recent broad popularity and can deliver nicotine at comparable levels to tobacco cigarettes, but effects on AAA development are unknown.

METHODS AND RESULTS

We evaluated the impact of daily e-cig vaping with nicotine on AAA using two complementary murine models and found that exposure enhanced aneurysm development in both models and genders. E-cigs induced changes in key mediators of AAA development including cytokine chitinase-3-like protein 1 (CHI3L1/Chil1) and its targeting microRNA-24 (miR-24). We show that nicotine triggers inflammatory signalling and reactive oxygen species while modulating miR-24 and CHI3L1/Chil1 in vitro and that Chil1 is crucial to e-cig-augmented aneurysm formation using a knockout model.

CONCLUSIONS

In conclusion our work shows increased aneurysm formation along with augmented vascular inflammation in response to e-cig exposure with nicotine. Further, we identify Chil1 as a key mediator in this context. Our data raise concerns regarding the potentially harmful long-term effects of e-cig nicotine vaping.

YKL-40 as a possible marker of neutrophilic asthma

Asthma is a heterogeneous chronic disorder of the airways, with inflammation and bronchial hyperresponsiveness as its major underlying phenomena. Asthmatics vary in terms of inflammation pattern, concomitant pathologies, and factors aggravating the course of the disease. As a result, there is a need for sensitive and specific biomarkers that could facilitate diagnosing asthma as well as phenotyping in everyday practice. Chitinases and chitinase-like proteins (CLPs) seem promising in this field. Chitinases are evolutionarily conserved hydrolases that degrade chitin. In contrast, CLPs bind chitin but do not have degrading activity. Mammalian chitinases and CLPs are produced by neutrophils, monocytes, and macrophages in response to parasitic or fungal infections. Recently, several questions have been raised about their role in chronic airway inflammation. Several studies demonstrated that overexpression of CLP YKL-40 was associated with asthma. Moreover, it correlated with exacerbation rate, therapy resistance, poor control of symptoms, and, inversely, with FEV₁. YKL-40 facilitated allergen sensitization and IgE production. Its concentration was elevated in bronchoalveolar lavage fluid after an allergen challenge. It was also found to promote the proliferation of bronchial smooth muscle cells and correlate with subepithelial membrane thickness. Thus, it may be involved in bronchial remodeling. Associations between YKL-40 and particular asthma phenotypes remain unclear. Some studies showed that YKL-40 correlates with blood eosinophilia and FeNO, suggesting a role in T2-high inflammation. Quite the opposite, cluster analyses revealed the highest upregulation in severe neutrophilic asthma and obesity-associated asthma. The main limitation in the practical application of YKL-40 as a biomarker is its low specificity. High serum levels of YKL-40 were also found in COPD and several malignancies, in addition to infectious and autoimmune diseases. To conclude, the level of YKL-40 correlates with asthma and some clinical features in the whole asthmatic population. The highest levels are found in neutrophilic and obesity-related phenotypes. However, due to its low specificity, the practical application of YKL-40 remains uncertain but could be useful in phenotyping, especially when combined with other biomarkers.

Increased visinin-like protein-1, YKL-40, lipocalin-2, and IL-23 levels in patients with migraine

BACKGROUND

Migraine is a type of primary headache caused by changes in the trigeminal system and has been reported to be associated with neurovascular inflammation of cerebral and extracerebral vessels.

OBJECTIVE

It is known that inflammation is an important process in the pathogenesis of migraine. It has been shown that the molecules of visinin-like protein 1 (Vilip-1), YKL-40, lipocalin-2 and interleukin (IL)-23 play a role in the inflammatory process. Our aim is to investigate the role of this molecule in the metabolic pathway of migraine disease.

METHODS

Fifty migraine patients with and without aura in the interictal period were included in the study. Vilip-1, YKL-40, lipocalin-2, and IL-23 levels were measured by ELISA method.

RESULTS

Serum vilip-1, YKL-40, lipocalin-2, and IL-23 levels were found to be significantly higher in migraine patients compared to the control group. We found that this molecule increased significantly in migraine subgroups compared to the control group (p < 0.001). A positive significant correlation was found between vilip-1 level and YKL-40 and lipocalin-2 levels in migraine patients. In addition, a positive correlation was observed between visual analogue scale score, number of days with pain and vilip-1 level (p < 0.01). The results of our study showed that activation of inflammatory mediators may play a role in the pathogenesis of migraine disease. In addition, our study is valuable in that inflammatory molecules are high in the interictal period and these biomarkers have never been analyzed in migraine patients. However, we still believe that larger studies are needed to explain the role of vilip-1, YKL-40, lipocalin-2, and IL-23 in the molecular mechanism of migraine disease.

Inflammatory Glycoprotein YKL-40 Is Elevated after Coronary Artery Bypass Surgery and Correlates with Leukocyte Chemotaxis and Myocardial Injury, a Pilot Study

The aim of the present study was to investigate the levels of YKL-40 during and after coronary artery bypass grafting surgery (CABG) and to establish possible connections between YKL-40 and markers of oxidative stress, inflammation, and myocardial injury. Patients undergoing elective CABG utilizing cardiopulmonary bypass (CPB) were recruited into the study. Blood samples were collected at the onset of anesthesia, during surgery and post-operatively. Levels of YKL-40, 8-isoprostane, interleukin-8 (IL-8), monocyte chemotactic protein-1 (MCP-1) and troponin T (TnT) were measured by immunoassay. YKL-40 levels increased significantly 24 h after CPB. Positive correlation was seen between post-operative TnT and YKL-40 levels (r = 0.457, p = 0.016) and, interestingly, baseline YKL-40 predicted post-operative TnT increase (r = 0.374, p = 0.050). There was also a clear association between YKL-40 and the chemotactic factors MCP-1 (r = 0.440, p = 0.028) and IL-8 (r = 0.484, p = 0.011) linking YKL-40 to cardiac inflammation and fibrosis following CABG. The present results show, for the first time, that YKL-40 is associated with myocardial injury and leukocyte-activating factors following coronary artery bypass surgery. YKL-40 may be a factor and/or biomarker of myocardial inflammation and injury and subsequent fibrosis following heart surgery.

Hyaladherins May be Implicated in Alcohol-Induced Susceptibility to Bacterial Pneumonia

Although the epidemiology of bacterial pneumonia and excessive alcohol use is well established, the mechanisms by which alcohol induces risk of pneumonia are less clear. Patterns of alcohol misuse, termed alcohol use disorders (AUD), affect about 15 million people in the United States. Compared to otherwise healthy individuals, AUD increase the risk of respiratory infections and acute respiratory distress syndrome (ARDS) by 2-4-fold. Levels and fragmentation of hyaluronic acid (HA), an extracellular glycosaminoglycan of variable molecular weight, are increased in chronic respiratory diseases, including ARDS. HA is largely involved in immune-assisted wound repair and cell migration. Levels of fragmented, low molecular weight HA are increased during inflammation and decrease concomitant with leukocyte levels following injury. In chronic respiratory diseases, levels of fragmented HA and leukocytes remain elevated, inflammation persists, and respiratory infections are not cleared efficiently, suggesting a possible pathological mechanism for prolonged bacterial pneumonia. However, the role of HA in alcohol-induced immune dysfunction is largely unknown. This mini literature review provides insights into understanding the role of HA signaling in host immune defense following excessive alcohol use. Potential therapeutic strategies to mitigate alcohol-induced immune suppression in bacterial pneumonia and HA dysregulation are also discussed.

Serum YKL-40 Level is Associated with Geriatric Nutritional Risk Index (GNRI) and γ-GTP in Hemodialysis Patients

Chitinase-3-like protein 1 (YKL-40) is a glycoprotein associated with inflammation and tissue remodeling that has recently been used as a marker of inflammation in hemodialysis (HD) patients. In this study, we aimed to determine whether YKL-40 has potential to serve as a nutritional parameter in Japanese HD patients. The serum YKL-40 concentration, hematological parameters, inflammatory marker levels, anthropometric measurements, and laboratory values were measured in 88 patients receiving HD. The geriatric nutritional risk index (GNRI) was used as a nutritional assessment tool. 45.4% of patients were malnourished. YKL-40 correlated positively with age, alkaline phosphatase, alanine transaminase and γ-glutamyl transpeptidase (γ-GTP) levels, but not with nutritional status, and correlated inversely with ankle brachial index score, a predictor of atherosclerosis. Furthermore, multiple regression analysis confirmed that γ-GTP, GNRI and age correlated with YKL-40. YKL-40 elevation was associated with γ-GTP, GNRI and age in HD patients. J. Med. Invest. 69 : 101-106, February, 2022.

Targeting Chitinase 1 and Chitinase 3-Like 1 as Novel Therapeutic Strategy of Pulmonary Fibrosis

Chitinase 1 (CHIT1) and chitinase 3-like-1 (CHI3L1), two representative members of 18-Glycosyl hydrolases family, are significantly implicated in the pathogenesis of various human diseases characterized by inflammation and remodeling. Notably, dysregulated expression of CHIT1 and CHI3L1 was noted in the patients with pulmonary fibrosis and their levels were inversely correlated with clinical outcome of the patients. CHIT1 and CHI3L1, mainly expressed in alveolar macrophages, regulate profibrotic macrophage activation, fibroblast proliferation and myofibroblast transformation, and TGF-β signaling and effector function. Although the mechanism or the pathways that CHIT1 and CHI3L1 use to regulate pulmonary fibrosis have not been fully understood yet, these studies identify CHIT1 and CHI3L1 as significant modulators of fibroproliferative responses leading to persistent and progressive pulmonary fibrosis. These studies suggest a possibility that CHIT1 and CHI3L1 could be reasonable therapeutic targets to intervene or reverse established pulmonary fibrosis. In this review, we will discuss specific roles and regulatory mechanisms of CHIT1 and CHI3L1 in profibrotic cell and tissue responses as novel therapeutic targets of pulmonary fibrosis.

Chitinase 3 like 1 is a regulator of smooth muscle cell physiology and atherosclerotic lesion stability

AIMS

Atherosclerotic cerebrovascular disease underlies the majority of ischaemic strokes and is a major cause of death and disability. While plaque burden is a predictor of adverse outcomes, plaque vulnerability is increasingly recognized as a driver of lesion rupture and risk for clinical events. Defining the molecular regulators of carotid instability could inform the development of new biomarkers and/or translational targets for at-risk individuals.

METHODS AND RESULTS

Using two independent human endarterectomy biobanks, we found that the understudied glycoprotein, chitinase 3 like 1 (CHI3L1), is up-regulated in patients with carotid disease compared to healthy controls. Further, CHI3L1 levels were found to stratify individuals based on symptomatology and histopathological evidence of an unstable fibrous cap. Gain- and loss-of-function studies in cultured human carotid artery smooth muscle cells (SMCs) showed that CHI3L1 prevents a number of maladaptive changes in that cell type, including phenotype switching towards a synthetic and hyperproliferative state. Using two murine models of carotid remodelling and lesion vulnerability, we found that knockdown of Chil1 resulted in larger neointimal lesions comprised by de-differentiated SMCs that failed to invest within and stabilize the fibrous cap. Exploratory mechanistic studies identified alterations in potential downstream regulatory genes, including large tumour suppressor kinase 2 (LATS2), which mediates macrophage marker and inflammatory cytokine expression on SMCs, and may explain how CHI3L1 modulates cellular plasticity.

CONCLUSION

CHI3L1 is up-regulated in humans with carotid artery disease and appears to be a strong mediator of plaque vulnerability. Mechanistic studies suggest this change may be a context-dependent adaptive response meant to maintain vascular SMCs in a differentiated state and to prevent rupture of the fibrous cap. Part of this effect may be mediated through downstream suppression of LATS2. Future studies should determine how these changes occur at the molecular level, and whether this gene can be targeted as a novel translational therapy for subjects at risk of stroke.

YKL-40 protein expression in human tumor samples and human tumor cell line xenografts: implications for its use in tumor models

BACKGROUND

YKL-40, also known as non-enzymatic chitinase-3 like-protein-1 (CHI3L1), is a glycoprotein expressed and secreted mainly by inflammatory cells and tumor cells. Accordingly, several studies demonstrated elevated YKL-40 serum levels in cancer patients and found YKL-40 to be correlated with a poor prognosis and disease severity in some tumor entities. YKL-40 was suggested to be involved in angiogenesis and extracellular matrix remodeling. As yet, however, its precise biological function remains elusive.

METHODS

As YKL-40 protein expression has only been investigated in few malignancies, we employed immunohistochemical detection in a large multi-tumor tissue microarray consisting of 2,310 samples from 72 different tumor entities. In addition, YKL-40 protein expression was determined in primary mouse xenograft tumors derived from human cancer cell lines.

RESULTS

YKL-40 could be detected in almost all cancer entities and was differently expressed depending on tumor stage and subtype (e.g., thyroid cancer, colorectal cancer, gastric cancer and ovarian cancer). While YKL-40 was absent in in vitro grown human cancer cell lines, YKL-40 expression was upregulated in xenograft tumor tissues in vivo.

CONCLUSIONS

These data provide new insights into YKL-40 expression at the protein level in various tumor entities and its regulation in tumor models. Our data suggest that upregulation of YKL-40 expression is a common feature in vivo and is finely regulated by tumor cell-microenvironment interactions.

New Angiogenic Regulators Produced by TAMs: Perspective for Targeting Tumor Angiogenesis

Simple Summary

Since the targeting of a single pro-angiogenic factor fails to improve oncological disease outcome, significant efforts have been made to identify new pro-angiogenic factors that could compensate for the deficiency of current therapy or act independently as single drugs. Our review aims to present the state-of-the art for well-known and recently described factors produced by macrophages that induce and regulate angiogenesis. A number of positive and negative regulators of angiogenesis in the tumor microenvironment are produced by tumor-associated macrophages (TAMs). Accumulating evidence has indicated that, apart from the well-known angiogenic factors, there are plenty of novel angiogenesis-regulating proteins that belong to different classes. We summarize the data regarding the direct or indirect mechanisms of the interaction of these factors with endothelial cells during angiogenesis. We highlight the recent findings that explain the limitations in the efficiency of current anti-angiogenic therapy approaches.

Abstract

Angiogenesis is crucial to the supply of a growing tumor with nutrition and oxygen. Inhibition of angiogenesis is one of the main treatment strategies for colorectal, lung, breast, renal, and other solid cancers. However, currently applied drugs that target VEGF or receptor tyrosine kinases have limited efficiency, which raises a question concerning the mechanism of patient resistance to the already developed drugs. Tumor-associated macrophages (TAMs) were identified in the animal tumor models as a key inducer of the angiogenic switch. TAMs represent a potent source not only for VEGF, but also for a number of other pro-angiogenic factors. Our review provides information about the activity of secreted regulators of angiogenesis produced by TAMs. They include members of SEMA and S100A families, chitinase-like proteins, osteopontin, and SPARC. The COX-2, Tie2, and other factors that control the pro-angiogenic activity of TAMs are also discussed. We highlight how these recent findings explain the limitations in the efficiency of current anti-angiogenic therapy. Additionally, we describe genetic and posttranscriptional mechanisms that control the expression of factors regulating angiogenesis. Finally, we present prospects for the complex targeting of the pro-angiogenic activity of TAMs.

Cerebrospinal Fluid YKL-40 and Neurogranin in Familial Alzheimer's Disease: A Pilot Study

BACKGROUND

YKL-40 and neurogranin are promising additional cerebrospinal fluid (CSF) biomarkers for Alzheimer's disease (AD) which reflect different underlying disease mechanisms.

OBJECTIVE

To compare the levels of CSF YKL-40 and neurogranin between asymptomatic carriers of familial AD (FAD) mutations (MC) and non-carriers (NC) from the same families. Another objective was to assess changes in YKL-40 and neurogranin, from the presymptomatic to clinical phase of FAD.

METHODS

YKL-40 and neurogranin, as well as Aβ42, total tau-protein, and phospho-tau, were measured in the CSF of 14 individuals carrying one of three FAD mutations, APPswe (p.KM670/671NL), APParc (p.E693G), and PSEN1 (p.H163Y), as well as in 17 NC from the same families. Five of the MC developed mild cognitive impairment (MCI) during follow-up.

RESULTS

In this pilot study, there was no difference in either CSF YKL-40 or neurogranin when comparing the presymptomatic MC to the NC. YKL-40 correlated positively with expected years to symptom onset and to age in both the MC and the NC, while neurogranin had no correlation to either variable in either of the groups. A subgroup of the participants underwent more than one CSF sampling in which half of the MC developed MCI during follow-up. The longitudinal data showed an increase in YKL-40 levels in the MC as the expected symptom onset approached. Neurogranin remained stable over time in both the MC and the NC.

CONCLUSION

These findings support a positive correlation between progression from presymptomatic to symptomatic AD and levels of CSF YKL-40, but not neurogranin.

Effects of Gallotannin-Enriched Extract of Galla Rhois on the Activation of Apoptosis, Cell Cycle Arrest, and Inhibition of Migration Ability in LLC1 Cells and LLC1 Tumors

Gallotannin (GT) and GT-enriched extracts derived from various sources are reported to have anti-tumor activity in esophageal, colon and prostate tumors, although their anti-tumor effects have not been determined in lung carcinomas. To investigate the anti-tumor activity of GT-enriched extract of galla rhois (GEGR) against lung carcinomas, alterations in the cytotoxicity, apoptosis activation, cell cycle progression, migration ability, tumor growth, histopathological structure, and the regulation of signaling pathways were analyzed in Lewis lung carcinoma (LLC1) cells and LLC1 tumor bearing C57BL/6NKorl mice, after exposure to GEGR. A high concentration of GT (69%) and DPPH scavenging activity (IC50=7.922 µg/ml) was obtained in GEGR. GEGR treatment exerted strong cytotoxicity, cell cycle arrest at the G2/M phase and subsequent activation of apoptosis, as well as inhibitory effects on the MAPK pathway and PI3K/AKT mediated cell migration in LLC1 cells. In the in vivo syngeneic model, exposure to GEGR resulted in suppressed growth of the LLC1 tumors, as well as inhibition of NF-κB signaling and their inflammatory cytokines. Taken together, our results provide novel evidence that exposure to GEGR induces activation of apoptosis, cell cycle arrest, and inhibition of cell migration via suppression of the MAPK, NF-κB and PI3K/AKT signaling pathways in LLC1 cells and the LLC1 syngeneic model.

Can YKL-40 be used as a biomarker for interstitial lung disease?: A systematic review and meta-analysis

BACKGROUND

Interstitial lung disease (ILD) has a poor prognosis and lacks specific biomarkers for early diagnosis, assessment of disease severity, and prognosis. YKL-40 levels were found to be elevated in patients with ILD, but these results are inconsistent. Therefore, we conducted a systematic review and meta-analysis to accurately study the relation between YKL-40 and ILD.

METHODS

We performed a systematic literature search in many databases (PubMed, Embase, the China National Knowledge Infrastructure, and Wanfang databases) and commercial Internet search engines to identify studies involving the role of YKL-40 in patients with ILD. The weighted mean difference with its 95% confidence interval were used to investigate the effect sizes. If obvious heterogeneity was found in the meta-analysis, the level of YKL-40 was directly compared by the Mann-Whitney test.

RESULTS

Sixteen eligible articles were finally identified. The results showed that the serum YKL-40 levels of patients with idiopathic pulmonary fibrosis, connective tissue-related ILD, sarcoidosis, cryptogenic tissue pneumonia, asbestosis-ILD, and idiopathic nonspecific interstitial pneumonia were higher than those in controls, but there was no increase in patients with pulmonary alveolar proteinosis. We also found that there are certain differences in the serum YKL-40 levels in patients with different types of ILD. The results showed that the bronchoalveolar lavage fluid YKL-40 levels of patients with idiopathic pulmonary fibrosis were significantly higher than that in controls. A systematic review indicated that there were correlations between the serum YKL-40 levels and lung function in patients with different ILD. In addition, YKL-40 may be used as a valuable biomarker for survival, with risk ratios ranging from 1.006 to 10.9.

CONCLUSIONS

This study suggests that YKL-40 may be a useful biomarker for the diagnosis and prognosis of ILD.

Influenza virus-mediated suppression of bronchial Chitinase-3-like 1 secretion promotes secondary pneumococcal infection

Infections of the lung are among the leading causes of death worldwide. Despite the preactivation of innate defense programs during viral infection, secondary bacterial infection substantially elevates morbidity and mortality rates. Particularly problematic are co-infections with influenza A virus (IAV) and the major bacterial pathogen Streptococcus pneumoniae. However, the molecular processes underlying the severe course of such co-infections are not fully understood. Previously, the absence of secreted glycoprotein Chitinase-3-like 1 (CHI3L1) was shown to increase pneumococcal replication in mice. We therefore hypothesized that an IAV preinfection decreases CHI3L1 levels to promote pneumococcal infection. Indeed, in an air-liquid interface model of primary human bronchial epithelial cells (hBECs), IAV preinfection interfered with apical but not basolateral CHI3L1 release. Confocal time-lapse microscopy revealed that the gradual loss of apical CHI3L1 localization during co-infection with influenza and S. pneumoniae coincided with the disappearance of goblet as well as ciliated cells and increased S. pneumoniae replication. Importantly, extracellular restoration of CHI3L1 levels using recombinant protein significantly reduced bacterial load in influenza preinfected bronchial models. Thus, recombinant CHI3L1 may provide a novel therapeutic means to lower morbidity and mortality associated with post-influenza pneumococcal infections.

YKL-40 as a novel biomarker in cardio-metabolic disorders and inflammatory diseases

Dyslipidaemia is associated with numerous health problems that include the combination of insulin resistance, hypertension and obesity, ie, metabolic syndrome. Although the use of statins to decrease serum low density lipoprotein cholesterol (LDL-C) has been an effective therapeutic in treating atherosclerosis, the persistence of high atherosclerotic risk, ie, residual risk, is notable and is not simply explained as a phenomenon of dyslipidaemia. As such, it is imperative that we identify new biomarkers to monitor treatment and more accurately predict future cardiovascular events. This athero-protective strategy includes the assessment of novel inflammatory biomarkers such as YKL-40. Recent evidence has implicated YKL-40 in patients with inflammatory diseases and cardio-metabolic disorders, making it potentially useful to evaluate disease severity, prognosis and survival. In this review, we summarize role of YKL-40 in the pathogenesis of cardio-metabolic disorders and explore its use as a novel biomarker for monitoring athero-protective therapy.

Chitinase-3 like-protein-1 function and its role in diseases

Non-enzymatic chitinase-3 like-protein-1 (CHI3L1) belongs to glycoside hydrolase family 18. It binds to chitin, heparin, and hyaluronic acid, and is regulated by extracellular matrix changes, cytokines, growth factors, drugs, and stress. CHI3L1 is synthesized and secreted by a multitude of cells including macrophages, neutrophils, synoviocytes, chondrocytes, fibroblast-like cells, smooth muscle cells, and tumor cells. It plays a major role in tissue injury, inflammation, tissue repair, and remodeling responses. CHI3L1 has been strongly associated with diseases including asthma, arthritis, sepsis, diabetes, liver fibrosis, and coronary artery disease. Moreover, following its initial identification in the culture supernatant of the MG63 osteosarcoma cell line, CHI3L1 has been shown to be overexpressed in a wealth of both human cancers and animal tumor models. To date, interleukin-13 receptor subunit alpha-2, transmembrane protein 219, galectin-3, chemo-attractant receptor-homologous 2, and CD44 have been identified as CHI3L1 receptors. CHI3L1 signaling plays a critical role in cancer cell growth, proliferation, invasion, metastasis, angiogenesis, activation of tumor-associated macrophages, and Th2 polarization of CD4+ T cells. Interestingly, CHI3L1-based targeted therapy has been increasingly applied to the treatment of tumors including glioma and colon cancer as well as rheumatoid arthritis. This review summarizes the potential roles and mechanisms of CHI3L1 in oncogenesis and disease pathogenesis, then posits investigational strategies for targeted therapies.

mTORC2/Rac1 Pathway Predisposes Cancer Aggressiveness in IDH1-Mutated Glioma

Isocitrate dehydrogenase (IDH) mutations are common genetic abnormalities in lower grade gliomas. The neomorphic enzyme activity of IDH mutants leads to tumor formation through epigenetic alteration, dysfunction of dioxygenases, and metabolic reprogramming. However, it remains elusive as to how IDH mutants regulate the pathways associated with oncogenic transformation and aggressiveness. In the present study, by using unbiased transcriptomic profiling, we showed that IDH1 mutations result in substantial changes in the gene sets that govern cellular motility, chemotaxis, and invasion. Mechanistically, rapamycin-insensitive companion of mammalian target of rapamycin (Rictor)/Ras-related C3 botulinum toxin substrate 1 (Rac1) signaling plays an essential role in the motility and proliferation of IDH1-mutated cells by prompting cytoskeleton reorganization, lamellipodia formation, and enhanced endocytosis. Targeting the Rictor/Rac1 pathway suppresses IDH1-mutated cells by limiting endocytosis and cell proliferation. Overall, our findings indicate a novel metabolic reprogramming mechanism of IDH1-mutated cells by exploiting metabolites from the extracellular milieu. Targeting the Rictor/Rac1 pathway could be an alternative therapeutic strategy for IDH1-mutated malignancies.

Prognosis and Reclassification by YKL-40 in Stable Coronary Artery Disease

Background

The inflammatory biomarker YKL‐40 has previously been studied as a potential risk marker in cardiovascular disease. We aimed to assess the prognostic reclassification potential of serum YKL‐40 in patients with stable coronary artery disease.

Methods and Results

The main study population was the placebo group of the CLARICOR (Effect of Clarithromycin on Mortality and Morbidity in Patients With Ischemic Heart Disease) trial. The primary outcome was a composite of acute myocardial infarction, unstable angina pectoris, cerebrovascular disease, and all‐cause mortality. We used Cox proportional hazards regression models adjusted for C‐reactive protein level and baseline cardiovascular risk factors. Improvement in prediction by adding serum YKL‐40 to the risk factors was calculated using the Cox‐Breslow method and c‐statistic. A total of 2200 patients were randomized to placebo, with a follow‐up duration of 10 years. YKL‐40 was associated with an increased risk of the composite outcome (hazard ratio per unit increase in (YKL‐40) 1.13, 95% CI 1.03–1.24, P=0.013) and all‐cause mortality (hazard ratio 1.32, 95% CI 1.17–1.49, P<0.0001). Considering whether a composite‐outcome event was more likely to have, or not have, occurred to date, we found 68.4% of such predictions to be correct when based on the standard predictors, and 68.5% when serum YKL‐40 was added as a predictor. Equivalent results were obtained with c‐statistics.

Conclusions

Higher serum YKL‐40 was independently associated with an increased risk of adverse cardiovascular outcomes and mortality. Addition of YKL‐40 did not improve risk prediction in patients with stable coronary artery disease.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov/. Unique identifier: NCT00121550.

Frontal cortex chitinase and pentraxin neuroinflammatory alterations during the progression of Alzheimer's disease

BACKGROUND

Chitinase 3-like 1 (CHI3L1), chitinase 3-like 2 (CHI3L2), and neuronal pentraxin II (NPTX2) are inflammatory biomarkers of Alzheimer's disease (AD). Although studies have demonstrated that cerebrospinal fluid levels of these proteins are changed in AD, no studies have undertaken a detailed examination of alterations in protein levels, cellular expression, and interaction with amyloid in the brain during the progression of AD.

METHODS

The study evaluated levels of both CHI3L1 and CHI3L2, NPTX2, ionized calcium-binding adapter molecule 1 (Iba1), complement component 1q (C1q), glial fibrillary acidic protein (GFAP), and CD44, in the frontal cortex of people who died with an antemortem clinical diagnosis of no cognitive impairment (NCI), mild cognitive impairment (MCI), mild/moderate AD (mAD), and severe AD (sAD) using immunoblot and immunohistochemical techniques.

RESULTS

CHI3L1-immunoreactive (-ir) astrocyte numbers were increased in the frontal cortex and white matter in sAD compared to NCI. On the other hand, increases in GFAP and Iba1-ir cell numbers were observed in MCI compared to NCI but only in white matter. Western blot analyses revealed significantly lower frontal cortex CHI3L2 levels, whereas CD44 levels were increased in sAD. No significant differences for CHI3L1, GFAP, C1q, and NPTX2 protein levels were detected between clinical groups. Strong significant correlations were found between frontal cortex CHI3L1 and Iba1-ir cell numbers in white matter and CHI3L1 and C1q protein levels in the early stages of the disease. C1q and Iba1, CD44 with CHI3L2, and GFAP protein levels were associated during disease progression. CHI3L1 and Iba1 cell numbers in white matter showed a significant associations with episodic memory and perceptual speed.

CONCLUSIONS

White matter CHI3L1 inflammatory response is associated with cognitive impairment early in the onset of AD.

YKL-39 as a Potential New Target for Anti-Angiogenic Therapy in Cancer

YKL-39 belongs to the evolutionarily conserved family of Glyco_18-containing proteins composed of chitinases and chitinase-like proteins. Chitinase-like proteins (CLPs) are secreted lectins that lack hydrolytic activity due to the amino acid substitutions in their catalytic domain and combine the functions of cytokines and growth factors. One of the major cellular sources that produce CLPs in various pathologies, including cancer, are macrophages. Monocytes recruited to the tumor site and programmed by tumor cells differentiate into tumor-associated macrophages (TAMs), which are the primary source of pro-angiogenic factors. Tumor angiogenesis is a crucial process for supplying rapidly growing tumors with essential nutrients and oxygen. We recently determined that YKL-39 is produced by tumor-associated macrophages in breast cancer. YKL-39 acts as a strong chemotactic factor for monocytes and stimulates angiogenesis. Chemotherapy is a common strategy to reduce tumor size and aggressiveness before surgical intervention, but chemoresistance, resulting in the relapse of tumors, is a common clinical problem that is critical for survival in cancer patients. Accumulating evidence indicates that TAMs are essential regulators of chemoresistance. We have recently found that elevated levels of YKL-39 expression are indicative of the efficiency of the metastatic process in patients who undergo neoadjuvant chemotherapy. We suggest YKL-39 as a new target for anti-angiogenic therapy that can be combined with neoadjuvant chemotherapy to reduce chemoresistance and inhibit metastasis in breast cancer patients.

Association of YKL-40 with endothelial dysfunction in patients with essential hypertension

Human cartilage glycoprotein 39 (YKL-40) is related with presence and extent of atherosclerosis, which can be a new biomarker of inflammation and endothelial dysfunction. The relationship between YKL-40 and endothelial dysfunction in patients with essential hypertension (EH) has not been intensively investigated. The relationship between serum level of YKL-40 and endothelial dysfunction was evaluated in 60 EH subjects and 50 normal control (NEH) subjects. Enzyme-linked immunosorbent assay (ELISA) was used to measure serum levels of YKL-40. Brachial artery flow-mediated vasodilation (FMD) was used to measure endothelial-dependent nitric oxide-mediated vasodilatory capacity as the function of endothelial index. This study demonstrated that YKL-40 expression was significantly increased ( p < 0.05) in EH subjects compared with NEH subjects. The FMD was significantly impaired in EH subjects compared with NEH subjects. YKL-40 was not only negatively correlated with FMD, but also with carotid artery intima-media thickness (IMT). Multiple liner regression analysis identified that YKL-40 was independent of FMD development. The level of YKL-40 was elevated in EH patients and inversely related with FMD and may be independent of endothelial dysfunction in EH.

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.

Serum YKL-40 predicts long-term outcome in patients undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction

Serum YKL-40, a potential inflammatory marker, is greatly increased at the early stage of ST-segment elevation myocardial infarction (STEMI). Here, we hypothesized that YKL-40 levels at admission could predict the long-term outcomes after STEMI.A total of 324 patients with acute STEMI undergoing primary percutaneous coronary intervention (PCI) were consecutively enrolled and followed for 24 months. The baseline clinical and procedural data were recorded, and serum YKL-40 levels at admission were measured using ELISA method. The endpoint of interest was major adverse cardiac event (MACE), including all-cause death, recurrent myocardial infarction, and hospitalization for heart failure.Patients with elevated serum YKL-40 levels (≥126.8 ng/mL) were more likely to be older and smoker and to present with type 2 diabetes, advanced Killip class, multivessel disease and intra-aortic balloon pump, with increased levels of admission glucose, triglyceride, and high-sensitivity C-reactive protein and decreased level of high-density lipoprotein cholesterol. During the follow-up period, the incidence of MACE was notably higher in the high than in the low YKL-40 groups (28.4% vs 11.1%, P < .001). Kaplan-Meier curve showed that elevated YKL-40 levels were associated with reduced MACE-free survivals (log-rank P < .001). In multivariate Cox regression analysis, we found that high serum YKL-40 level was an independent predictor of MACE after controlling for clinical and angiographic variables (hazard ratio: 1.65, 95% confidence interval: 1.14-2.39, P = .008).The results of our study indicate that serum YKL-40 may be used as a biomarker to predict the long-term outcome after PCI in patients with STEMI.

Caffeic acid and ellagic acid ameliorate adjuvant-induced arthritis in rats via targeting inflammatory signals, chitinase-3-like protein-1 and angiogenesis

Rheumatoid arthritis (RA) is a chronic inflammatory arthropathy that principally attacks the joints. The present study aimed to explore the potential anti-arthritic effects of caffeic acid and ellagic acid in adjuvant-induced arthritis, compared to celecoxib. The current study also explored the underlying molecular mechanisms e.g., pro-inflammatory signals including chitinase-3-like protein-1 (CHI3L1); a glycoprotein that correlates with RA joint destruction besides angiogenesis, oxidative stres and apoptosis. Interestingly, caffeic and ellagic acids attenuated the severity of arthritis with comparable efficacy to celecoxib. Both agents effectively mitigated paw edema and inflammatory cell infiltration and protected the joint tissues against pannus formation along with cartilage and bone destruction. Notably, they also lowered the paw expression of NF-κB and the downstream effector CHI3L1 and its synthesis inducer IL-1β. They also lowered the levels of the tissue remodeling factor MMP-9 and the angiogenic signal VEGF in rat paws. Both agents also suppressed serum oxidative stress via diminishing lipid peroxides and nitric oxide together with augmentation of reduced glutathione in arthritic animals. Regarding apoptosis, they attenuated paw caspase-3 levels, favoring cell survival. Together, these favorable findings may advocate the use of caffeic and ellagic acids as adjunct modalities for the management of RA to mitigate joint damage.

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.

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.

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.

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.

Mortality prediction in stable hemodialysis patients is refined by YKL-40, a 40-kDa glycoprotein associated with inflammation

Chronic inflammation contributes to increased mortality in hemodialysis (HD) patients. YKL-40 is a novel marker of inflammation, tissue remodeling, and highly expressed in macrophages inside vascular lesions. Elevated levels of YKL-40 have been reported for HD patients but how it integrates into the proinflammatory mediator network as a predictor of mortality remains elusive. We studied serum YKL-40, Interleukin-6 (IL-6), high-sensitivity C-reactive protein, monocyte chemotactic protein-1 (MCP-1), and interferon-gamma induced protein-10 (IP-10) in 475 chronic hemodialysis patients. Patients were followed for mortality for a median of 37 [interquartile range: 25-49] months and checked for interrelation of the measured mediators. To plot cumulative incidence functions, patients were stratified into terciles per YKL-40, IL-6, MCP-1, and IP-10 levels. Multivariable Cox regression models were built to examine associations of YKL-40, IP-10, and MCP-1 with all-cause and cause-specific mortality. Net reclassification improvement was calculated for the final models containing YKL-40 and IL-6. Increased YKL-40 was independently associated with age, IP-10, and IL-6 serum levels. After adjustment for demographic and laboratory parameters, comorbidities, and IL-6, only YKL-40 significantly improved risk prediction for all-cause (hazard ratio 1.4; 95% confidence interval 1.1-1.8) and cardiovascular mortality (hazard ratio 1.5; 95% confidence interval 1.03-2.2). Thus, in contrast to other biomarkers of aberrant macrophage activation, YKL-40 reflects inflammatory activity, which is not covered by IL-6. Mechanistic and prospective studies are needed to test for causal involvement of YKL-40 and whether it might qualify as a therapeutic target.

Serum YKL-40, a prognostic marker in patients with large-artery atherosclerotic stroke

BACKGROUND AND PURPOSE

Inflammation comprises important aspects of large-artery atherosclerosis (LAA) stroke pathophysiology. YKL-40 is a new and emerging biomarker that is associated with both acute and chronic inflammations. Elevated serum concentrations of YKL-40 have been reported in patients with atherosclerosis and other cardiovascular diseases. This study investigates whether serum YKL-40 concentrations on admission can predict 3-month clinical outcomes after LAA stroke.

METHODS

We recruited control patients (n=85) and those with LAA stroke (n=141) according to the TOAST classification system. The modified Rankin scale at 3 months after stroke was used to evaluate the prognosis. The prognostic accuracy was assessed by the receiver operating characteristic curve.

RESULTS

Serum YKL-40 level was significantly higher for LAA patients than for controls (P<.001). Patients with poor outcomes (n=36) had significantly increased serum YKL-40 concentrations on admission (P=.01). High YKL-40 levels predicted poor functional outcome (OR=6.47, P=.02). Moreover, the combination of YKL-40 level and the NIHSS score could improve the prognostic accuracy of the NIHSS in predicting functional outcome (combined areas under the curve, 0.87; 95% CI, 0.80-0.94; P<.001).

CONCLUSIONS

The level of serum YKL-40 is a significant and independent biomarker to predict the clinical outcome of LAA stroke.

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.

Correlation of Chitinase 3-Like 1 Single Nucleotide Polymorphisms with Hepatocellular Carcinoma in Taiwan

Hepatocellular carcinoma (HCC) is the second leading cause of cancer death in Taiwan. Multiple risk factors, such as chronic hepatitis B or C virus infection, carcinogen exposure, cirrhosis, and various single-nucleotide polymorphisms (SNPs), are considered to contribute to hepatocarcinogenesis. Chitinase-3-like protein 1 (CHI3L1), a biomarker implicated in inflammation and tissue remodeling, plays a promoting role in angiogenesis, antiapoptosis, and cell proliferation. This study investigated the role of CHI3L1 SNPs in HCC susceptibility and clinicopathology. Real-time polymerase chain reaction was used to analyze four SNPs of CHI3L1 in 343 patients with HCC and 686 cancer-free controls. We found associations with HCC susceptibility in CHI3L1 rs880633 polymorphism carriers with genotypes (TC+CC). We observed that HCC patients had lower frequencies of CHI3L1 rs6691378 polymorphisms with the variant genotype GA+AA than the wild-type carriers with distant metastasis and positive HBsAg did. In 200 HBsAg negative HCC patients, we observed that the CHI3L1 rs4950928 polymorphisms carriers with the variant genotype CG+GG had higher frequencies of vascular invasion. Finally, carriers of CHI3L1 rs6691378 and 10399805 polymorphisms with the variant genotypes GA+AA showed lower levels of alpha-fetoprotein in HCC laboratory status. In conclusion, our results indicate that patients with CHI3L1 rs880633 variant genotypes TC+CC are at a higher risk of HCC. CHI3L1 polymorphisms rs880633 or rs4950928 may be potential candidates for predicting poor HCC prognosis and clinical status.