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

Uncovering novel mechanisms of chitinase-3-like protein 1 in driving inflammation-associated cancers

Chitinase-3-like protein 1 (CHI3L1) is a secreted glycoprotein that is induced and regulated by multiple factors during inflammation in enteritis, pneumonia, asthma, arthritis, and other diseases. It is associated with the deterioration of the inflammatory environment in tissues with chronic inflammation caused by microbial infection or autoimmune diseases. The expression of CHI3L1 expression is upregulated in several malignant tumors, underscoring the crucial role of chronic inflammation in the initiation and progression of cancer. While the precise mechanism connecting inflammation and cancer is unclear, the involvement of CHI3L1 is involved in chronic inflammation, suggesting its role as a contributing factor to in the link between inflammation and cancer. CHI3L1 can aggravate DNA oxidative damage, induce the cancerous phenotype, promote the development of a tumor inflammatory environment and angiogenesis, inhibit immune cells, and promote cancer cell growth, invasion, and migration. Furthermore, it participates in the initiation of cancer progression and metastasis by binding with transmembrane receptors to mediate intracellular signal transduction. Based on the current research on CHI3L1, we explore introduce the receptors that interact with CHI3L1 along with the signaling pathways that may be triggered during chronic inflammation to enhance tumorigenesis and progression. In the last section of the article, we provide a brief overview of anti-inflammatory therapies that target CHI3L1.

Anti-chitinase-3-like 1 antibody attenuated atopic dermatitis-like skin inflammation through inhibition of STAT3-dependent CXCL8 expression

BACKGROUND AND PURPOSE

Chitinase-3-like 1 (CHI3L1) causes skin inflammation in the progression of atopic dermatitis. We investigated if anti-CHI3L1 antibody could prevent the development of atopic dermatitis and its mechanisms of action.

EXPERIMENTAL APPROACH

The effect of CHI3L1 antibody on phthalic anhydride-induced atopic dermatitis animal model and in vitro reconstructed human skin (RHS) model were investigated. Expression and release of atopic dermatitis-related cytokines were determined using an enzyme-linked immunosorbent assay, and RT-qPCR, STAT3 and CXCL8 signalling were measured by western blotting.

KEY RESULTS

Anti-CHI3L1 antibody suppressed phthalic anhydride-induced epidermal thickening, clinical score, IgE level and infiltration of inflammatory cells, and reduced phthalic anhydride-induced inflammatory cytokines concentration. In addition, CHI3L1 antibody treatment inhibited the expression of STAT3 activity in phthalic anhydride-treated skin. It was also confirmed that CHI3L1 antibody treatment alleviated atopic dermatitis-related inflammation in the RHS model. The inhibitory effects of CHI3L1 antibody was similar or more effective compared with that of the IL-4 antibody. We further found that CHI3L1 is associated with CXCL8 by protein-association network analysis. siRNA of CHI3L1 blocked the mRNA levels of CHI3L1, IL-1β, IL-4, CXCL8, TSLP, and the expression of CHI3L1 and p-STAT, and the level of CXCL8, whereas recombinant level of CXCL8 was elevated. Moreover, siRNA of STAT3 reduced the mRNA level of these cytokines. CHI3L1 and p-STAT3 expression correlated with the reduced CXCL8 level in the RHS in vitro model.

CONCLUSION AND IMPLICATIONS

Our data demonstrated that CHI3L1 antibody could be a promising effective therapeutic drug for atopic dermatitis.

Serum YKL-40 Levels, Leukocyte Profiles, and Acute Exacerbations of Advanced COPD

Little information exists on YKL-40-a key protein in tissue remodeling-and complete blood count (CBC) parameters during acute exacerbations of advanced chronic obstructive pulmonary disease (COPD). This pilot exploratory study (August 2020-January 2021) investigated the connection between serum YKL-40 levels and CBC profile in sex- and age-matched individuals with severe COPD (GOLD stage III, n = 23, median age = 66 years, 65.21% males) and very severe COPD (GOLD stage IV, n = 24, median age = 66.5 years, 74.81% males). The measured parameters were serum YKL-40, absolute leukocyte count (ALLC), absolute neutrophil count (ANC), neutrophil percentage, absolute lymphocyte count (ALC), lymphocyte percentage, neutrophil-to-lymphocyte ratio (NLR), absolute eosinophil count (AEC), eosinophil percentage, absolute monocyte count (AMC), monocyte percentage, absolute basophil count (ABC), basophil percentage, hemoglobin levels, and hematocrit concentrations. No significant inter-group differences were observed. However, high YKL-40 subjects (n = 23)-as stratified via median YKL-40 (3934.5 pg/mL)-showed significantly increased neutrophil percentage and NLR but significantly lower lymphocyte-, eosinophil-, and basophil-related parameters compared to low YKL-40 patients (n = 24). These results reveal multidimensional, YKL-40-associated changes in leukocyte profile of patients with advanced COPD during acute exacerbations, with potential implications for personalized treatment.

CSE reduces OTUD4 triggering lung epithelial cell apoptosis via PAI-1 degradation

Ovarian tumor family deubiquitinase 4 (OTUD4), a member of the OTU deubiquitinating enzyme, is implicated to decrease in cancer to regulate cell apoptosis. However, the role of OTUD4 in cigarette smoke induced epithelial cell apoptosis and its mechanism have not been elucidated. In this study, we showed that OTUD4 protein reduced in CSE treated mice and airway epithelial cells. OTUD4 silence aggravated cell apoptosis and emphysematous change in the lung tissue of cigarette smoke extract (CSE) treated mice. Additionally, restoration of OTUD4 in the lung of mice alleviated CSE induced apoptosis and emphysematous morphology change. The effect of OTUD4 on cell apoptosis was also confirmed in vitro. Through protein profile screening, we identified that OTUD4 may interact with plasminogen activator inhibitor 1(PAI-1). We further confirmed that OTUD4 interacted with PAI-1 for de-ubiquitination and inhibiting CSE induced PAI-1 degradation. Furthermore, the protective role of OTUD4 in airway epithelial cells apoptosis was blocked by PAI-1 deactivation. Taken together, our data suggest that OTUD4 regulates cigarette smoke (CS)-triggered airway epithelial cell apoptosis via modulating PAI-1 degradation. Targeting OUTD4/PAI-1 signaling might potentially provide a therapeutic target against the lung cell apoptosis in cigarette smoke (CS)-induced emphysema.

Increased CAP37 Expression in Stable Chronic Obstructive Pulmonary Disease

OBJECTIVE

Cationic antimicrobial protein of 37 kDa (CAP37), a neutrophil-derived protein originally identified for its antimicrobial activity, is now known to have many regulatory effects on host cells. However, its role in the pathogenesis of chronic obstructive pulmonary disease (COPD) has not been studied. We therefore investigated the expression of CAP37 in COPD and its effects on airway structural cells, including bronchial epithelial cells, smooth muscle cells, and fibroblasts.

METHODS

CAP37 was detected in the lung tissue, sputum, and plasma of COPD patients and the control subjects, as well as in the neutrophils stimulated by cigarette smoke extract (CSE). BEAS-2B cells, human bronchial smooth muscle cells (HBSMCs), and MRC-5 cells were treated with CAP37 or an anti-CAP37 antibody plus CAP37. Interleukin (IL)-6 and IL-8 were detected in the BEAS-2B cells. The cell proliferation was analyzed in the HBSMCs. Collagens were also detected in the MRC-5 cells.

RESULTS

The expression of CAP37 was increased in the lung tissue and sputum supernatant of the COPD patients compared with the control subjects. The sputum supernatant CAP37 levels were inversely correlated with the forced expiratory volume in the first second percentage predicted in COPD. CAP37 was induced by CSE stimulation in the peripheral blood neutrophils from healthy non-smokers. CAP37 induced expression of IL-6 and IL-8 in BEAS-2B cells, and collagen expression of lung fibroblasts (MRC-5 cells). However, CAP37 did not significantly alter the proliferation of the HBSMCs.

CONCLUSION

Our findings indicated that neutrophil-derived CAP37 may be involved in airway inflammation and fibrosis in COPD via affecting the bronchial epithelial cells, and fibroblasts, thus suggesting a possible role of CAP37 in the development and progression of COPD.

Plasma Proteomics Enable Differentiation of Lung Adenocarcinoma from Chronic Obstructive Pulmonary Disease (COPD)

Chronic obstructive pulmonary disease (COPD) is a major risk factor for the development of lung adenocarcinoma (AC). AC often develops on underlying COPD; thus, the differentiation of both entities by biomarker is challenging. Although survival of AC patients strongly depends on early diagnosis, a biomarker panel for AC detection and differentiation from COPD is still missing. Plasma samples from 176 patients with AC with or without underlying COPD, COPD patients, and hospital controls were analyzed using mass-spectrometry-based proteomics. We performed univariate statistics and additionally evaluated machine learning algorithms regarding the differentiation of AC vs. COPD and AC with COPD vs. COPD. Univariate statistics revealed significantly regulated proteins that were significantly regulated between the patient groups. Furthermore, random forest classification yielded the best performance for differentiation of AC vs. COPD (area under the curve (AUC) 0.935) and AC with COPD vs. COPD (AUC 0.916). The most influential proteins were identified by permutation feature importance and compared to those identified by univariate testing. We demonstrate the great potential of machine learning for differentiation of highly similar disease entities and present a panel of biomarker candidates that should be considered for the development of a future biomarker panel.

Long noncoding RNA GAS5 attenuates cigarette smoke-induced airway remodeling by regulating miR-217-5p/PTEN axis

Airway remodeling is a remarkable pathological characteristic of chronic obstructive pulmonary disease (COPD), and long noncoding RNAs have been demonstrated to participate in COPD development and pathogenesis. Here, we investigate the role of long noncoding RNA GAS5 in cigarette smoke (CS)-induced airway remodeling. GAS5 expression is significantly lower in lung tissues of CS-exposed mice than in tissues of control mice without exposure to CS. Forced GAS5 overexpression suppresses CS-induced airway inflammation and remodeling. GAS5 overexpression also inhibits CS extract-induced inflammatory-cytokine expression and fibroblast activation in vitro. Regarding the mechanism, GAS5 acts as a sponge of miR-217-5p, thereby increasing PTEN expression. MiR-217-5p overexpression and PTEN knockdown separately reverse the inhibitory effects of GAS5 overexpression on the inflammatory-cytokine expression and fibroblast activation. Collectively, these results suggest that GAS5 can suppress airway inflammation and fibroblast activation by regulating miR-217-5p/PTEN axis, which may help develop novel therapeutic strategies against COPD.

Serum YKL-40 Levels Predict Endotypes and Associate with Postoperative Recurrence in Patients with Chronic Rhinosinusitis with Nasal Polyps

Background

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a global health concern with high heterogeneity and rate of postoperative recidivation. YKL-40 is a pivotal pro-inflammatory mediator to promote Th2 immune response which is involved in many inflammatory diseases. This study aimed to investigate the predictive value of serum YKL-40 in CRSwNP endotypes and postoperative recurrence.

Methods

We recruited 80 primary CRSwNP, 40 recurrent CRSwNP patients and 40 healthy controls (HCs) in this study, and the serum and tissue specimens were collected. The middle turbinate mucosa tissue collected from patients undergoing septoplasty was used as control. Serum YKL-40 concentrations were detected by enzyme-linked immunosorbent assay (ELISA), and tissue YKL-40 mRNA and protein levels were examined using quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC). The difference of YKL-40 expression was compared among different group. Multivariate analysis and receiver operating characteristic (ROC) curve were performed to evaluate the value of serum YKL-40 in discriminating eosinophilic CRSwNP (eCRSwNP) and predicting postoperative recurrence.

Results

The serum YKL-40 levels in CRSwNP patients were higher than HCs, especially in eCRSwNP patients (p < 0.05). The elevated YKL-40 levels positively correlated with blood eosinophil percentage, tissue eosinophil counts and percentages (p < 0.05). The serum YKL-40 levels in recurrent CRSwNP patients were markedly enhanced than primary CRSwNP patients (p < 0.05). The YKL-40 mRNA and protein levels were significantly elevated in CRSwNP patients compared to HCs, especially in eCRSwNP and recurrent CRSwNP group. Multivariate analysis and ROC curve exhibited that serum YKL-40 might be a promising indicator in distinguishing CRSwNP endotypes and predicting postoperative recurrence.

Conclusion

Our data suggested that YKL-40 might be unregulated in CRSwNP and associated with mucosal eosinophilia and recurrence. Serum YKL-40 appeared to a novel biomarker for predicting CRSwNP endotypes and postoperative recurrence of CRSwNP.

Identification of serum prognostic biomarkers of severe COVID-19 using a quantitative proteomic approach

The COVID-19 pandemic is an unprecedented threat to humanity that has provoked global health concerns. Since the etiopathogenesis of this illness is not fully characterized, the prognostic factors enabling treatment decisions have not been well documented. Accurately predicting the progression of the disease would aid in appropriate patient categorization and thus help determine the best treatment option. Here, we have introduced a proteomic approach utilizing data-independent acquisition mass spectrometry (DIA-MS) to identify the serum proteins that are closely associated with COVID-19 prognosis. Twenty-seven proteins were differentially expressed between severely ill COVID-19 patients with an adverse or favorable prognosis. Ingenuity Pathway Analysis revealed that 15 of the 27 proteins might be regulated by cytokine signaling relevant to interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF), and their differential expression was implicated in the systemic inflammatory response and in cardiovascular disorders. We further evaluated practical predictors of the clinical prognosis of severe COVID-19 patients. Subsequent ELISA assays revealed that CHI3L1 and IGFALS may serve as highly sensitive prognostic markers. Our findings can help formulate a diagnostic approach for accurately identifying COVID-19 patients with severe disease and for providing appropriate treatment based on their predicted prognosis.

Increased Plasma YKL-40 Level and Chitotriosidase Activity in Cystic Fibrosis Patients

We investigated plasma YKL-40 levels and chitotriosidase (CHIT1) activity in patients with cystic fibrosis (CF) lung disease and evaluated clinically relevant factors that may affect their levels. Plasma samples were obtained from pediatric (n = 19) and adult patients (n = 15) during exacerbation, discharge, and stable period of the disease. YKL-40 levels and chitotriosidase activity were measured by enzyme-linked immunosorbent assay and fluorometric assay, respectively. Data were compared with healthy children and adults of similar age. YKL-40 levels of pediatric and adult CF patients at all periods were significantly higher than controls (p < 0.001 and p < 0.05). CHIT1 activities of adult patients at all periods were significantly higher compared to controls (p < 0.05). On the other hand, CHIT1 activities of pediatric CF patients were similar with controls. YKL-40 levels of exacerbation period of adult CF patients were negatively correlated with forced vital capacity (FVC) (r =  - 0.800, p = 0.014) and forced expiratory volume in 1 s (FEV1) (r =  - 0.735, p = 0.008). YKL-40 levels in the exacerbation period of pediatric CF patients were negatively correlated with FVC (r =  - 0.697, p = 0.0082) and FEV1 (r =  - 0.720, p = 0.006). CHIT1 activity may be a valuable marker of chronic inflammation in adult CF patients who suffer from CF for a longer period compared to pediatric patients. Increased YKL-40 levels in both pediatric and adult patients compared to controls may point to a role in between CF pathology.

Chronic Obstructive Pulmonary Disease: Epidemiology, Biomarkers, and Paving the Way to Lung Cancer

Chronic obstructive pulmonary disease (COPD), the frequently fatal pathology of the respiratory tract, accounts for half a billion cases globally. COPD manifests via chronic inflammatory response to irritants, frequently to tobacco smoke. The progression of COPD from early onset to advanced disease leads to the loss of the alveolar wall, pulmonary hypertension, and fibrosis of the respiratory epithelium. Here, we focus on the epidemiology, progression, and biomarkers of COPD with a particular connection to lung cancer. Dissecting the cellular and molecular players in the progression of the disease, we aim to shed light on the role of smoking, which is responsible for the disease, or at least for the more severe symptoms and worse patient outcomes. We summarize the inflammatory conditions, as well as the role of EMT and fibroblasts in establishing a cancer-prone microenvironment, i.e., the soil for ‘COPD-derived’ lung cancer. We highlight that the major health problem of COPD can be alleviated via smoking cessation, early diagnosis, and abandonment of the usage of biomass fuels on a global basis.

[Value of chitinase-like protein YKL-40 in bronchoalveolar lavage fluid for predicting refractory Mycoplasma pneumoniae pneumonia in children]

OBJECTIVE

To evaluate the value of chitinase-like protein YKL-40 in bronchoalveolar lavage fluid (BALF) for predicting refractory Mycoplasma pneumoniae pneumonia (RMPP) in children.

METHODS

A total of 50 children with common Mycoplasma pneumoniae pneumonia (MPP) and 22 children with RMPP were enrolled. The two groups were compared in terms of clinical features, laboratory examination results, imaging findings, and YKL-40 levels in BALF. The receiver operating characteristic (ROC) curve was used to evaluate the value of YKL-40 in BALF for predicting RMPP.

RESULTS

Compared with the common MPP group, the RMPP group had significantly higher incidence rates of fever, shortness of breath, lung consolidation, and pleural effusion (P < 0.05) and significantly higher serum levels of C-reactive protein and lactate dehydrogenase (P < 0.05). The RMPP group had a significantly higher level of YKL-40 in BALF than the common MPP group (P < 0.05). The ROC curve plotted based on the level of YKL-40 in BALF had an area under the ROC curve of 0.750, a sensitivity of 72.7% and a specificity of 64.0% for predicting RMPP.

CONCLUSIONS

There is an increase in the level of YKL-40 in BALF in children with RMPP, and the level of YKL-40 in BALF has a certain value for predicting RMPP.

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.

Alveolar Macrophage Phenotype and Compartmentalization Drive Different Pulmonary Changes in Mouse Strains Exposed to Cigarette Smoke

COPD can manifest itself with different clinical phenotypes characterized by different disease progression and response to therapy. Although a remarkable number of studies have been carried out, little is known about the mechanisms underlying phenotypes that could guide the development of viable future therapies. Several murine strains mirror some human phenotypes after smoke exposure. It was of interest to investigate in these strains whether different pattern of activation of macrophages, and their distribution in lungs, is associated to changes characterizing different phenotypes. We chose C57Bl/6, and Lck deficient mice, which show significant emphysema, DBA/2 mice that develop changes similar to those of "pulmonary fibrosis/emphysema syndrome", p66Shc ko mice that develop bronchiolitis with fibrosis but not emphysema, and finally ICR mice that do not develop changes at 7 months after smoke exposure. Unlike other strains, ICR mice show very few activated macrophages (Mac-3 positive) mostly negative to M1 or M2 markers. On the other hand, a large population of M1 macrophages predominates in the lung periphery of DBA/2, C57Bl/6 and in Lck deficient mice, where emphysema is more evident. M2 macrophages are mainly observed in subpleural and intraparenchymal areas of DBA/2 mice and around bronchioles of p66Shc ko mice where fibrotic changes are present. We observed slight but significant differences in mRNA expression of iNOS, ECF-L, arginase 1, IL-4, IL-13 and TGF-β between air- and smoke-exposed mice. These differences together with the different compartmentalization of macrophages may offer an explanation for the diversity of lesions and their distribution that we observed among the strains.

Chitinases and Chitinase-Like Proteins in Obstructive Lung Diseases - Current Concepts and Potential Applications

Chitinases, enzymes that cleave chitin’s chain to low molecular weight chitooligomers, are widely distributed in nature. Mammalian chitinases belong to the 18-glycosyl-hydrolase family and can be divided into two groups: true chitinases with enzymatic activity (AMCase and chitotriosidase) and chitinase-like proteins (CLPs) molecules which can bind to chitin or chitooligosaccharides but lack enzymatic activity (eg, YKL-40). Chitinases are thought to be part of an innate immunity against chitin-containing parasites and fungal infections. Both groups of these hydrolases are lately evaluated also as chemical mediators or biomarkers involved in airway inflammation and fibrosis. The aim of this article is to present the current knowledge on the potential role of human chitinases and CLPs in the pathogenesis, diagnosis, and course of obstructive lung diseases. We also assessed the potential role of chitinase and CLPs inhibitors as therapeutic targets in chronic obstructive pulmonary disease and asthma.

Chitotriosidase Activity in Plasma and COPD Exacerbations

INTRODUCTION

This study aimed to determine the association between plasma chitotriosidase activity and the clinical characteristics and exacerbation rate of COPD patients.

METHODS

The study comprised 97 patients with COPD. Their clinical characteristics and a history of exacerbations in the last 12 months were noted. Plasma chitotriosidase activity was determined. Patients were followed up for 12 months, and the number of moderate and severe exacerbations during this period was recorded.

RESULTS

Chitotriosidase activity positively correlated with patient age (rho = 0.217, p = 0.036) and inversely with CAT (rho = - 0.240, p = 0.020). There was no correlation with lung function. Chitotriosidase activity was significantly lower in patients with a history of ≥ 2 exacerbations compared to patients without a history of exacerbations (93 [38-312] vs. 264 [168-408] nmol/h/mL, p = 0.033). Overall, there was no difference in chitotriosidase activity between patients with or without observed exacerbations. Patients with a history of ≥ 1 exacerbation and ≥ 1 observed exacerbation had higher chitotriosidase activity compared to patients without further exacerbations (240 [144-456] vs. 52 [39-240] nmol/h/mL, p = 0.035). Multivariate analysis identified FEV₁ (HR 0.976, 95% CI 0.956-0.996, p = 0.016) and blood eosinophil percentage (HR 1.222, 95% CI 1.048-1.424, p = 0.011) as independent predictors of future exacerbations in the total patient population, while in patients with a history of ≥ 1 exacerbation ,the only independent predictor was chitotriosidase activity (HR per 10 nmol/h/mL 1.028, 95% CI 1.002-1.055, p = 0.037).

CONCLUSION

While mixed associations between chitotriosidase activity and clinical outcomes were seen, chitotriosidase activity could be a predictor of future exacerbations in patients with a history of ≥ 1 exacerbation in the past  12 months.

Chitotriosidase: a biomarker of activity and severity in patients with sarcoidosis

Background

Serum chitotriosidase is a promising biomarker that has shown high specificity and sensitivity in patients with sarcoidosis. The aim of this study was to investigate correlations between serum chitotriosidase, clinical phenotypes, disease localizations and different radiological lung involvement and to identify clinical features associated with over-expression of chitotriosidase in a large cohort of sarcoidosis patients.

Methods

Chitotriosidase activity was evaluated in a population of 694 consecutive patients (males 39%, age 55.8 ± 12.8 years). Clinical and respiratory functional characteristics, Clinical Outcome Scale (COS) classification, clinical phenotypes proposed by the GenPhenResA project, and radiological assessment, including CT scan, were collected. Serum sampling and clinical and functional assessments at follow-up were also included.

Results

Significantly higher chitotriosidase activity was observed in sarcoidosis patients than in healthy controls (p < 0.0001). Evidence of lung fibrosis with reticular abnormalities and traction bronchiectasis at High resolution CT, presence of multiple extrapulmonary sarcoid localizations and increased 24-h urinary excretion of calcium were associated with significantly higher chitotriosidase activity (p < 0.005). Patients with remitted or minimal disease had lower values of chitotriosidase than patients with persistent disease. At follow-up, patients who required an increase in steroid dose showed an increase in its activity.

Conclusions

Chitotriosidase is a reliable biomarker of sarcoidosis. It is increased in patients with sarcoidosis correlating with disease activity, severity and multiorgan dissemination. Steroid therapy tended to reduce chitotriosidase expression, however it responded in cases of disease relapse.

[Association of YKL-40 in bronchoalveolar lavage fluid with airway damage in children with Mycoplasma pneumoniae pneumonia]

OBJECTIVE

To investigate the association of YKL-40 in bronchoalveolar lavage fluid (BALF) with airway damage in children with Mycoplasma pneumoniae pneumonia (MPP).

METHODS

A total of 60 children with MPP who were admitted to the hospital were enrolled as the MPP group, and 12 children with bronchial foreign bodies were enrolled as the control group. According to the imaging findings, the MPP group was further divided into 3 subgroups: pulmonary patchy shadow (n=34), pulmonary consolidation (n=19) and pulmonary ground-glass opacity (n=7). According to the bronchoscopic findings, the MPP group was further divided into 3 subgroups: mucosal congestion/edema (n=38), mucous secretion (n=18) and plastic bronchitis (n=4). The clinical manifestations and laboratory characteristics of the children with MPP were analyzed, the expression of YKL-40 in BALF was measured.

RESULTS

The MPP group had significantly higher levels of serum lactate dehydrogenase and BALF YKL-40 than the control group (P<0.05). The pulmonary consolidation subgroup had significantly higher levels of serum C-reactive protein and lactate dehydrogenase than the pulmonary patchy shadow subgroup (P<0.05), and the pulmonary consolidation and pulmonary ground-glass opacity subgroups had a significantly higher level of BALF YKL-40 than the pulmonary patchy shadow subgroup (P<0.05). The plastic bronchitis subgroup had a significantly higher level of BALF YKL-40 than the mucous secretion and mucosal congestion/edema subgroups (P<0.05). The mucous secretion and plastic bronchitis subgroups had a significantly higher proportion of children with shortness of breath than the mucosal congestion/edema subgroup (P<0.05). The plastic bronchitis subgroup had significantly higher serum levels of C-reactive protein and lactate dehydrogenase than the mucosal congestion/edema subgroup (P<0.05).

CONCLUSIONS

The level of BALF YKL-40 is associated with airway damage and disease severity in children with MPP.

Serum chitinase-like protein YKL-40 is linked to small airway function in children with asthmatic symptoms

BACKGROUND

Lung function impairment among asthmatic children begins in early life, and biomarkers for identifying this impairment are needed. The chitinase-like protein YKL-40 has been associated with asthma and lung function in adults, but studies in children have yielded conflicting results. We evaluated the potential of YKL-40 and other systemic biomarkers for identifying lung function deficits in children with asthmatic symptoms.

METHODS

We determined the levels of serum YKL-40, periostin, and high-sensitivity C-reactive protein (hs-CRP) from the blood samples of 49 children with asthmatic symptoms. Lung function was assessed with impulse oscillometry (IOS) and spirometry, combined with an exercise challenge and a bronchodilator test. Fractional exhaled nitric oxide was measured at multiple flow rates.

RESULTS

Serum levels of YKL-40 showed significant correlations with most IOS indices at baseline (P = .008-.039), but there was no association between YKL-40 and spirometry parameters. Neither periostin nor hs-CRP were associated with baseline lung function. Children with a significant response in either the exercise challenge or the bronchodilator test had increased serum levels of YKL-40 (P = .003) and periostin (P = .035). YKL-40 correlated significantly with the blood neutrophil count (r_s  = .397, P = .005) but was not associated with biomarkers of eosinophilic inflammation.

CONCLUSION

Serum YKL-40 is a potential biomarker for lung function deficits in children with asthmatic symptoms. These deficits appear to be focused on small airways and may remain undetected with spirometry.

[Association of YKL-40 in bronchoalveolar lavage fluid with airway damage in children with Mycoplasma pneumoniae pneumonia]

OBJECTIVE

To investigate the association of YKL-40 in bronchoalveolar lavage fluid (BALF) with airway damage in children with Mycoplasma pneumoniae pneumonia (MPP).

METHODS

A total of 60 children with MPP who were admitted to the hospital were enrolled as the MPP group, and 12 children with bronchial foreign bodies were enrolled as the control group. According to the imaging findings, the MPP group was further divided into 3 subgroups: pulmonary patchy shadow (n=34), pulmonary consolidation (n=19) and pulmonary ground-glass opacity (n=7). According to the bronchoscopic findings, the MPP group was further divided into 3 subgroups: mucosal congestion/edema (n=38), mucous secretion (n=18) and plastic bronchitis (n=4). The clinical manifestations and laboratory characteristics of the children with MPP were analyzed, the expression of YKL-40 in BALF was measured.

RESULTS

The MPP group had significantly higher levels of serum lactate dehydrogenase and BALF YKL-40 than the control group (P<0.05). The pulmonary consolidation subgroup had significantly higher levels of serum C-reactive protein and lactate dehydrogenase than the pulmonary patchy shadow subgroup (P<0.05), and the pulmonary consolidation and pulmonary ground-glass opacity subgroups had a significantly higher level of BALF YKL-40 than the pulmonary patchy shadow subgroup (P<0.05). The plastic bronchitis subgroup had a significantly higher level of BALF YKL-40 than the mucous secretion and mucosal congestion/edema subgroups (P<0.05). The mucous secretion and plastic bronchitis subgroups had a significantly higher proportion of children with shortness of breath than the mucosal congestion/edema subgroup (P<0.05). The plastic bronchitis subgroup had significantly higher serum levels of C-reactive protein and lactate dehydrogenase than the mucosal congestion/edema subgroup (P<0.05).

CONCLUSIONS

The level of BALF YKL-40 is associated with airway damage and disease severity in children with MPP.

Strategies for measuring airway mucus and mucins

Mucus secretion and mucociliary transport are essential defense mechanisms of the airways. Deviations in mucus composition and secretion can impede mucociliary transport and elicit airway obstruction. As such, mucus abnormalities are hallmark features of many respiratory diseases, including asthma, cystic fibrosis and chronic obstructive pulmonary disease (COPD). Studying mucus composition and its physical properties has therefore been of significant interest both clinically and scientifically. Yet, measuring mucus production, output, composition and transport presents several challenges. Here we summarize and discuss the advantages and limitations of several techniques from five broadly characterized strategies used to measure mucus secretion, composition and mucociliary transport, with an emphasis on the gel-forming mucins. Further, we summarize advances in the field, as well as suggest potential areas of improvement moving forward.

SIRT1 protects against urban particulate matter-induced airway inflammation

Purpose

Particulate matter (PM) has been implicated as a risk factor for airway injury. However, the molecular mechanisms remain largely unclear. The goal of this study was to determine whether sirtuin1 (SIRT1), an anti-inflammatory and antiaging protein, protects against PM-induced airway inflammation.

Methods

The effect of SIRT1 on PM-induced airway inflammation was assessed by using in vivo models of airway inflammation induced by PM and in vitro culture of human bronchial epithelial (HBE) cells exposed to PM, resveratrol (SIRT1 activator), or both.

Results

PM-stimulated HBE cells showed a significant decrease in SIRT1 but a notable increase in inflammatory cytokines. SIRT1 gene silencing further enhanced PM-induced expression of inflammatory cytokines. In contrast, resveratrol, a SIRT1 activator, reduced the expression of these cytokines compared with the control cells. In vivo, SIRT1 expression was significantly decreased in lung tissues of PM-exposed mice. Interestingly, resveratrol treatment reversed the enhanced total cells, neutrophils and inflammatory cytokines in PM-induced mice. Moreover, SIRT1 mediated PM-induced inflammatory cytokines expression at least partly through MAPK pathways.

Conclusion

These findings suggest that SIRT1 is involved in the pathogenesis of PM-induced airway inflammation and activation of SIRT1 could prevent airway disorders or disease exacerbations induced by airborne particulate pollution.

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.

Heparin-binding epidermal growth factor contributes to COPD disease severity by modulating airway fibrosis and pulmonary epithelial-mesenchymal transition

Although airway fibrosis and epithelial-mesenchymal transition (EMT) contribute to airway remodeling in chronic obstructive pulmonary disease (COPD), the mechanisms underlying their development have not been fully elucidated. In the present study, we aimed to assess heparin-binding epidermal growth factor (HB-EGF) expression in the airways of patients with COPD and to elucidate the possible role of HB-EGF in the pathology of COPD. Sputum and lung tissue HB-EGF expression was evaluated in control subjects and patients with COPD. The relationships between HB-EGF expression, disease severity, collagen deposition (fibrosis), and EMT were investigated. In vitro, human bronchial epithelial (HBE) cells and lung fibroblast cells exposed to the recombinant HB-EGF, collagen deposition and EMT were assessed. We found that sputum HB-EGF expression was significantly increased in patients with COPD compared with non-smokers and smokers without COPD. There was a significant positive correlation between sputum HB-EGF and COPD assessment test (CAT) score. HB-EGF expression was significantly increased in the lung tissue samples of patients with COPD and associated with collagen deposition and N- and E-cadherin, and vimentin expression. In vitro, HB-EGF promoted collagen production in lung fibroblasts. Moreover, HB-EGF induced the EMT process through induction of N-and E-cadherin, and vimentin expression in HBE cells. Collectively, HB-EGF induces airway remodeling by modulating airway fibrosis and pulmonary EMT, and contributes to the COPD severity. The current data may provide insight into the underlying pathogenesis of COPD, in which HB-EGF has an important pathogenic role.

Annexin A1 is elevated in patients with COPD and affects lung fibroblast function

Purpose

Fibrosis in peripheral airways is responsible for airflow limitation in chronic obstructive pulmonary disease (COPD). Annexin A1 modulates several key biological events during inflammation. However, little is known about its role in airway fibrosis in COPD. We investigated whether levels of Annexin A1 were upregulated in patients with COPD, and whether it promoted airway fibrosis.

Methods

We quantified serum Annexin A1 levels in never-smokers (n=12), smokers without COPD (n=11), and smokers with COPD (n=22). Correlations between Annexin A1 expression and clinical indicators (eg, lung function) were assessed. In vitro, human bronchial epithelial (HBE) cells were exposed to cigarette smoke extract (CSE) and Annexin A1 expression was assessed. Primary human lung fibroblasts were isolated from patients with COPD and effects of Annexin A1 on fibrotic deposition of lung fibroblasts were evaluated.

Results

Serum Annexin A1 was significantly higher in patients with Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines stage III or IV than in those with GOLD stages I or II (12.8±0.8 ng/mL versus 9.8±0.7 ng/mL; p=0.016). Annexin A1 expression was negatively associated with airflow obstruction (forced expiratory volume in one second % predicted; r=−0.72, p<0.001). In vitro, Annexin A1 was significantly increased in CSE-exposed HBE cells in a time- and concentration-dependent manner. Annexin A1 promoted lung fibroblasts proliferation, migration, differentiation, and collagen deposition via the ERK1/2 and p38 mitogen-activated protein kinase pathways.

Conclusion

Annexin A1 expression is upregulated in patients with COPD and affects lung fibroblast function. However, more studies are needed to clarify the role of Annexin A1 in airway fibrosis of COPD.

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.

The role of YKL40 in the pathogenesis of CRS with nasal polyps

BACKGROUND

Many Chinese patients who experience chronic rhinosinusitis with nasal polyps (CRSwNP) have been shown to exhibit specifically enhanced TH1/TH17 responses and excessive neutrophil accumulation without demonstrating significant eosinophilia. These patients may be subject to different pathologies and therapies compared to Western patients. YKL40 can be produced by neutrophil and is associated with many inflammatory diseases, while its role in the pathogenesis of chronic rhinosinusitis (CRS) has yet to be determined.

OBJECTIVE

The aim of this study was to investigate the relationship between the expression level and biologic role of YKL40 in CRS.

METHODS

YKL40 expression was examined via quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), immunohistochemistry, and Western blot. Human nasal epithelia cells (HNECs) were isolated to detect YKL40 expression in response to specific inflammatory stimulation.

RESULTS

YKL40 expression levels were significantly higher in NP patients compared to the turbinates of CRSsNP/CRSwNP and the control group and can be strongly activated by stimulation with IL-4 in vitro and suppressed by the other pro-inflammatory cytokines; lipopolysaccharide (LPS) and dexamethasone also caused significant decreases in YKL40 expression in HNECs.

CONCLUSIONS

YKL40 may play a significant role in Chinese patients with CRSwNP. The molecular mechanisms identified here may aid in the design of new therapeutic strategies for improving the clinical outcomes of Chinese patients.

Airway microbiota signals anabolic and catabolic remodeling in the transplanted lung

BACKGROUND

Homeostatic turnover of the extracellular matrix conditions the structure and function of the healthy lung. In lung transplantation, long-term management remains limited by chronic lung allograft dysfunction, an umbrella term used for a heterogeneous entity ultimately associated with pathological airway and/or parenchyma remodeling.

OBJECTIVE

This study assessed whether the local cross-talk between the pulmonary microbiota and host cells is a key determinant in the control of lower airway remodeling posttransplantation.

METHODS

Microbiota DNA and host total RNA were isolated from 189 bronchoalveolar lavages obtained from 116 patients post lung transplantation. Expression of a set of 11 genes encoding either matrix components or factors involved in matrix synthesis or degradation (anabolic and catabolic remodeling, respectively) was quantified by real-time quantitative PCR. Microbiota composition was characterized using 16S ribosomal RNA gene sequencing and culture.

RESULTS

We identified 4 host gene expression profiles, among which catabolic remodeling, associated with high expression of metallopeptidase-7, -9, and -12, diverged from anabolic remodeling linked to maximal thrombospondin and platelet-derived growth factor D expression. While catabolic remodeling aligned with a microbiota dominated by proinflammatory bacteria (eg, Staphylococcus, Pseudomonas, and Corynebacterium), anabolic remodeling was linked to typical members of the healthy steady state (eg, Prevotella, Streptococcus, and Veillonella). Mechanistic assays provided direct evidence that these bacteria can impact host macrophage-fibroblast activation and matrix deposition.

CONCLUSIONS

Host-microbes interplay potentially determines remodeling activities in the transplanted lung, highlighting new therapeutic opportunities to ultimately improve long-term lung transplant outcome.

YKL-40 (Chitinase 3-like I) is expressed in a subset of astrocytes in Alzheimer's disease and other tauopathies

BACKGROUND

The innate immune system is known to be involved early in the pathogenesis of Alzheimer's disease (AD) and other neurodegenerative disorders. The inflammatory response in the central nervous system can be measured postmortem or through a series of inflammatory mediator surrogates. YKL-40 (also named Chitinase-3-like I) has been frequently investigated in body fluids as a surrogate marker of neuroinflammation in AD and other neurological disorders. However, the expression pattern of YKL-40 in the human brain with neurodegenerative pathology remains poorly investigated. Our aim was to study the cellular expression pattern of YKL-40 in the brain of patients with clinical and neuropathological criteria for AD (n = 11); three non-AD tauopathies: Pick's disease (PiD; n = 8), corticobasal degeneration (CBD; n = 8) and progressive supranuclear palsy (PSP; n = 9) and a group of neurologically healthy controls (n = 6).

METHODS

Semiquantitative neuropathological evaluation and quantitative confocal triple immunofluorescence studies were performed. An in-house algorithm was used to detect and quantify pathology burden of random regions of interest on a full tissue-section scan. Kruskal-Wallis and Dunn's multiple comparison tests were performed for colocalization and quantification analyses.

RESULTS

We found that brain YKL-40 immunoreactivity was observed in a subset of astrocytes in all four diseases and in controls. There was a strong colocalization between YKL-40 and the astroglial marker GFAP but not with neuronal nor microglial markers. Intriguingly, YKL-40-positive astrocytes were tau-negative in PSP, CBD and PiD. The number of YKL-40-positive astrocytes was increased in tauopathies compared with that in controls. A positive correlation was found between YKL-40 and tau immunoreactivities.

CONCLUSIONS

This study confirms that YKL-40 is expressed by a subset of astrocytes in AD and other tauopathies. YKL-40 expression is elevated in several neurodegenerative conditions and correlates with tau pathology.

Elevated expression of placental growth factor is associated with airway-wall vascular remodelling and thickening in smokers with asthma

The increased expression of placental growth factor (PlGF) in chronic obstructive pulmonary disease and allergy-related asthma suggests its role in the pathogenesis of these diseases. In asthmatic smokers, airway remodelling is accompanied by an accelerated decline in lung function. However, whether PlGF contributes to the persistent airflow obstruction and vascular remodelling typically seen in asthmatic smokers is unknown. In this study we measured lung function, airway-wall thickening, and PlGF levels in serum and induced sputum in 74 asthmatic and 42 healthy smokers and never-smokers. Using human lung microvascular endothelial cells (HLMECs), we evaluated the in vitro effects of PlGF on each step of vascular remodelling, including proliferation, migration, stress-fibre expression, and tubule formation. Our data showed significantly higher serum and sputum PlGF levels in asthma patients, especially asthmatic smokers, than in healthy controls. Serum and sputum PlGF levels correlated negatively with post-bronchodilator forced expiratory volume in 1 s (FEV₁) and the FEV₁/forced vital capacity, but positively with airway-wall thickening. Stimulation of HLMECs with rhPlGF promoted all of the steps of airway-microvascular remodelling. These findings provide insights into the influence of cigarette smoking on the structural changes in the airways of asthmatics and the important pathogenic role played by PlGF.