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

Structure-Based Discovery of High-Affinity Small Molecule Ligands and Development of Tool Probes to Study the Role of Chitinase-3-Like Protein 1

Chitinase-3-like-1 (CHI3L1), also known as YKL-40, is a glycoprotein linked to inflammation, fibrosis, and cancer. This study explored CHI3L1's interactions with various oligosaccharides using microscale thermophoresis (MST) and AlphaScreen (AS). These investigations guided the development of high-throughput screening assays to assess interference of small molecules in binding between CHI3L1 and biotinylated small molecules or heparan sulfate-based probes. Small molecule binders of YKL-40 were identified in our chitotriosidase inhibitors library with MST and confirmed through X-ray crystallography. Based on cocrystal structures of potent hit compounds with CHI3L1, small molecule probes 19 and 20 were designed for an AS assay. Structure-based optimization led to compounds 30 and 31 with nanomolar activities and drug-like properties. Additionally, an orthogonal AS assay using biotinylated heparan sulfate as a probe was developed. The compounds' affinity showed a significant correlation in both assays. These screening tools and compounds offer novel avenues for investigating the role of CHI3L1.

YKL-40 as a biomarker in various inflammatory diseases: A review

YKL-40 or Chitinase-3-Like Protein 1 (CHI3L1) is a highly conserved glycoprotein that binds heparin and chitin in a non-enzymatic manner. It is a member of the chitinase protein family 18, subfamily A, and unlike true chitinases, YKL-40 is a chitinase-like protein without enzymatic activity for chitin. Although its accurate function is yet unknown, the pattern of its expression in the normal and disease states suggests its possible engagement in apoptosis, inflammation and remodeling or degradation of the extracellular matrix. During an inflammatory response, YKL-40 is involved in a complicated interaction between host and bacteria, both promoting and attenuating immune response and potentially being served as an autoantigen in a vicious circle of autoimmunity. Based on its pathophysiology and mechanism of action, the aim of this review was to summarize research on the growing role of YKL-40 as a persuasive biomarker for inflammatory diseases' early diagnosis, prediction and follow-up (e.g., cardiovascular, gastrointestinal, endocrinological, immunological, musculoskeletal, neurological, respiratory, urinary, infectious) with detailed structural and functional background of YKL-40.

Serum MMP3 and IL1-RA levels may be useful biomarkers for detecting asthma and chronic obstructive pulmonary disease overlap in patients with asthma

Background

Asthma and chronic obstructive pulmonary disease (COPD) overlap (ACO) is characterized by concurrent features of asthma and COPD. Since disease pathogenesis, severities, and treatments differ between asthma and ACO, it is important to differentiate them.

Objective

To clarify and compare the characteristics of ACO and asthma and identify the serum biomarkers for differentiating them, especially in older patients.

Methods

This study used the data of 639 participants from the nationwide cohort study, the NHOM-Asthma study, an asthma registry in Japan, with complete information on smoking history, respiratory function, and serum biomarkers. ACO was defined as the self-reported comorbidity of COPD or emphysema, or with obstructive pulmonary function and smoking history (pack-years≥10). The clinical characteristics of patients with ACO and asthma without COPD were compared. The serum biomarkers for differentiation were examined using receiver operating characteristic curves and multivariable analysis. The associations between the biomarkers and age were also analyzed.

Results

Of the 639 asthma patients, 125 (19.6%) were diagnosed with ACO; these patients were older and male-dominant and had a higher prevalence of comorbidities such as hypertension, diabetes, and stroke. Among the serum biomarkers that were significantly different between ACO and asthma without COPD, the YKL-40/CHI3L1, MMP3, and IL-1RA levels showed a high area under the curve for discriminating ACO. Only the MMP3 and IL-1RA levels were significantly higher among ACO patients, regardless of age and sex; the YKL-40/CHI3L1 levels were not different due to the effect of age.

Conclusion

MMP3 and IL-1RA may be useful serum biomarkers for distinguishing ACO from asthma.

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.

Bronchial epithelial and airway smooth muscle cell interactions in health and disease

Chronic pulmonary diseases such as asthma, COPD, and Idiopathic pulmonary fibrosis are significant causes of mortality and morbidity worldwide. Currently, there is no radical treatment for many chronic pulmonary diseases, and the treatment options focus on relieving the symptoms and improving lung function. Therefore, efficient therapeutic agents are highly needed. Bronchial epithelial cells and airway smooth muscle cells and their crosstalk play a significant role in the pathogenesis of these diseases. Thus, targeting the interactions of these two cell types could open the door to a new generation of effective therapeutic options. However, the studies on how these two cell types interact and how their crosstalk adds up to respiratory diseases are not well established. With the rise of modern research tools and technology, such as lab-on-a-chip, organoids, co-culture techniques, and advanced immunofluorescence imaging, a substantial degree of evidence about these cell interactions emerged. Hence, this contribution aims to summarize the growing evidence of bronchial epithelial cells and airway smooth muscle cells crosstalk under normal and pathophysiological conditions. The review first discusses the impact of airway smooth muscle cells on the epithelium in inflammatory settings. Later, it examines the role of airway smooth muscle cells in the early development of bronchial epithelial cells and their recovery after injury. Then, it deliberates the effects of both healthy and stressed epithelial cells on airway smooth muscle cells, taking into account three themes; contraction, migration, and proliferation.

Serum YKL-40 Levels in Patients with Asthma or COPD: A Pilot Study

Background and Objectives: Bronchial asthma (BA) and chronic obstructive pulmonary disease (COPD) are not only common obstructive respiratory conditions but also major causes of morbidity and mortality worldwide. There is, however, a surprising lack of blood-based biomarkers for separating between these pulmonary disorders. The aim of this study was to assess the practical relevance of using serum YKL-40, single or combined, for this purpose. Materials and Methods: Subjects included Romanian patients with BA (n = 24) or COPD (n = 27). YKL-40, fibrinogen, pre-treatment C-reactive protein (CRP), post-treatment CRP, erythrocyte sedimentation rate, interleukin 6 (IL-6), procalcitonin (PCT), absolute neutrophil count, neutrophil percentage, absolute lymphocyte count, lymphocyte percentage, absolute eosinophil count, and eosinophil percentage were measured and compared between these patients. Results: This is the first study investigating the clinical significance of serum YKL-40 in delineating between COPD and BA in Caucasian populations. Only fibrinogen and YKL-40 levels were different between COPD and BA, with the measured values being significantly elevated. These patients exhibited distinct inflammatory profiles. Using the upper quartiles of these variables for the pooled study population (YKL-40: 5100 pg/mL; fibrinogen: 552 mg/dL) as cut-off values, subjects were classified into high or low groups. High YKL-40 adults revealed significantly increased PCT levels. High fibrinogen subjects, by contrast, showed significantly elevated IL-6 concentrations and pre-treatment CRP levels. Low YKL-40 and fibrinogen patients showed the absence of COPD. Conclusions: Combined use of serum YKL-40 and fibrinogen may be useful for identifying the absence of COPD.

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.

Effect of Vitamin D on YKL-40: Rat Hypercholesterolemia Model

BACKGROUND AND OBJECTIVES

YKL-40 is considered to be associated with cardiovascular disease (CVD). In this study, the effect of serum 25(OH) vitamin D [25(OH)VitD] differences between groups on YKL-40 was evaluated on a hypercholesterolemia rat model.

METHODS

Thirty-two male rats (wistar albino) were equally divided into 4 groups. The first group was the control group; the second group was high-cholesterol (H-CH) adequate vitamin D (VitD) group (H-Ade^VD). The third group was the H-CH deficient VitD group (H-Def^VD), and the last group was designed with the H-CH supplement VitD (H-Sup^VD). The feeding process consisted of 2 stages. At the first stage (5 months), the H-Def^VD group was fed on VitD deficient chow, while the other groups (control, H-Ade^VD, H-Sup^VD) were fed on standard chow. At the second stage (3 months), the H-Ade^VD and the H-Sup^VD groups were fed on the H-CH chow, whereas the H-Def^VD group was fed on the H-CH-VitD deficient chow. Moreover, the H-Sup^VD group was given 100 IU/kg/day VitD along with the H-CH chow.

RESULTS

Compared with the control group, interleukin-6 (IL-6), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), and YKL-40 values in the H-Def^VD groups increased significantly (p<0.001, p<0.001, p=0.009, p=0.005; sequentially).

CONCLUSION

It can be concluded that VitD can suppress the YKL-40, thus, it will prevent CVD development in rat. Therefore, further clinical studies related with human will reveal the effect of VitD and YKL-40 on CVD development.

Serum IL-6, sAXL, and YKL-40 as systemic correlates of reduced brain structure and function in Alzheimer's disease: results from the DELCODE study

BACKGROUND

Neuroinflammation constitutes a pathological hallmark of Alzheimer's disease (AD). Still, it remains unresolved if peripheral inflammatory markers can be utilized for research purposes similar to blood-based beta-amyloid and neurodegeneration measures. We investigated experimental inflammation markers in serum and analyzed interrelations towards AD pathology features in a cohort with a focus on at-risk stages of AD.

METHODS

Data of 74 healthy controls (HC), 99 subjective cognitive decline (SCD), 75 mild cognitive impairment (MCI), 23 AD relatives, and 38 AD subjects were obtained from the DELCODE cohort. A panel of 20 serum biomarkers was determined using immunoassays. Analyses were adjusted for age, sex, APOE status, and body mass index and included correlations between serum and CSF marker levels and AD biomarker levels. Group-wise comparisons were based on screening diagnosis and routine AD biomarker-based schematics. Structural imaging data were combined into composite scores representing Braak stage regions and related to serum biomarker levels. The Preclinical Alzheimer's Cognitive Composite (PACC5) score was used to test for associations between the biomarkers and cognitive performance.

RESULTS

Each experimental marker displayed an individual profile of interrelations to AD biomarkers, imaging, or cognition features. Serum-soluble AXL (sAXL), IL-6, and YKL-40 showed the most striking associations. Soluble AXL was significantly elevated in AD subjects with pathological CSF beta-amyloid/tau profile and negatively related to structural imaging and cognitive function. Serum IL-6 was negatively correlated to structural measures of Braak regions, without associations to corresponding IL-6 CSF levels or other AD features. Serum YKL-40 correlated most consistently to CSF AD biomarker profiles and showed the strongest negative relations to structure, but none to cognitive outcomes.

CONCLUSIONS

Serum sAXL, IL-6, and YKL-40 relate to different AD features, including the degree of neuropathology and cognitive functioning. This may suggest that peripheral blood signatures correspond to specific stages of the disease. As serum markers did not reflect the corresponding CSF protein levels, our data highlight the need to interpret serum inflammatory markers depending on the respective protein's specific biology and cellular origin. These marker-specific differences will have to be considered to further define and interpret blood-based inflammatory profiles for AD research.

Pharmacological Inhibition of Chitotriosidase (CHIT1) as a Novel Therapeutic Approach for Sarcoidosis

Introduction

Methods

Results

Conclusion

The Value of Serum YKL-40 and TNF-α in the Diagnosis of Acute ST-Segment Elevation Myocardial Infarction

Background

Acute ST-segment elevation myocardial infarction (STEMI) is a serious cardiovascular disease that poses a great threat to the life and health of patients. Therefore, early diagnosis is important for STEMI patient treatment and prognosis. The purpose of this study was to investigate the value of serum YKL-40 and TNF-α in the diagnosis of STEMI.

Methods

From October 2020 to February 2022, 120 patients with STEMI were admitted to the Chest Pain Center of the Second People's Hospital of Hefei, and 81 patients with negative coronary angiography were selected as the control group. Serum YKL-40 and TNF-α concentrations were measured by sandwich ELISA. Pearson correlation was used to analyze the correlation between serum YKL-40, TNF-α, and serum troponin I (cTnI) in STEMI patients; multivariate logistic regression analysis was used to screen independent risk factors for STEMI. Three diagnostic models were constructed: cTnI univariate model (model A), combined serum YKL-40 and TNF-α model other than cTnI (model B), and combined cTnI and serum YKL-40 and TNF-α model (model C). We assessed the clinical usefulness of the diagnostic model by comparing AUC with decision curve analysis (DCA).

Results

Serum YKL-40 and TNF-α in the STEMI group were significantly higher than those in the control group (P < 0.001). On Pearson correlation analysis, there was a significant positive correlation between serum YKL-40, TNF-α, and cTnI levels in STEMI patients. Multivariate logistic regression analysis showed that serum YKL-40 and TNF-α were independent risk factors for the development of STEMI. The results of ROC analysis showed that the area under the curve (AUC) of serum YKL-40 for predicting the occurrence of STEMI was 0.704. The AUC of serum TNF-α for predicting the occurrence of STEMI was 0.852. The AUC of cTnI as a traditional model, model A, for predicting the occurrence of STEMI was 0.875. Model B predicted STEMI with an AUC of 0.851. The addition of serum YKL-40 and serum TNF-α to the traditional diagnostic model composed of cTnI constituted a new diagnostic model; that is, the AUC of model C for predicting the occurrence of STEMI was 0.930. Model C had a better net benefit between a threshold probability of 70–95% for DCA.

Conclusion

In this study, we demonstrate the utility of serum YKL-40 and TNF-α as diagnostic markers for STEMI and the clinical utility of diagnostic models by combining serum YKL-40 and TNF-α with cTnI.

Neutrophils and Asthma

Although eosinophilic inflammation is characteristic of asthma pathogenesis, neutrophilic inflammation is also marked, and eosinophils and neutrophils can coexist in some cases. Based on the proportion of sputum cell differentiation, asthma is classified into eosinophilic asthma, neutrophilic asthma, neutrophilic and eosinophilic asthma, and paucigranulocytic asthma. Classification by bronchoalveolar lavage is also performed. Eosinophilic asthma accounts for most severe asthma cases, but neutrophilic asthma or a mixture of the two types can also present a severe phenotype. Biomarkers for the diagnosis of neutrophilic asthma include sputum neutrophils, blood neutrophils, chitinase-3-like protein, and hydrogen sulfide in sputum and serum. Thymic stromal lymphoprotein (TSLP)/T-helper 17 pathways, bacterial colonization/microbiome, neutrophil extracellular traps, and activation of nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 pathways are involved in the pathophysiology of neutrophilic asthma and coexistence of obesity, gastroesophageal reflux disease, and habitual cigarette smoking have been associated with its pathogenesis. Thus, targeting neutrophilic asthma is important. Smoking cessation, neutrophil-targeting treatments, and biologics have been tested as treatments for severe asthma, but most clinical studies have not focused on neutrophilic asthma. Phosphodiesterase inhibitors, anti-TSLP antibodies, azithromycin, and anti-cholinergic agents are promising drugs for neutrophilic asthma. However, clinical research targeting neutrophilic inflammation is required to elucidate the optimal treatment.

Prevalence of depression in patients with sarcopenia and correlation between the two diseases: systematic review and meta-analysis

BACKGROUND

Depression may be the most common cause of emotional distress later in life and can significantly reduce the quality of life in elderly individuals. Sarcopenia is a syndrome characterized by the continuous loss of skeletal muscle mass and decreased strength and function. In recent years, many studies have shown a correlation between sarcopenia and depression. The present study aimed to investigate the prevalence of depression among individuals with sarcopenia and to ascertain whether sarcopenia is independently associated with depression.

METHODS

We systematically searched the PubMed, Embase, and Google Scholar databases for papers on sarcopenia published up to 31 August 2021. We reviewed the literature on the number of individuals with sarcopenia, the number of individuals with both sarcopenia and depression, and the odds ratio (OR) of sarcopenia to depression. Statistical analyses were performed using Meta-DiSc 1.4 software and Stata version 12.0.

RESULTS

Nineteen articles met the inclusion criteria for review: nine reported both prevalence and ORs, four described prevalence only, and six detailed the ORs only. Regarding prevalence, there were 1476 cases of sarcopenia and 364 of depression in the selected studies; the mean age of the patients was 75.5 years, and the overall prevalence of depression was 0.28 [95% confidence interval (CI): 0.21-0.36]. Significant heterogeneity was noted (P < 0.001; I²  = 92.2%). In the case of ORs, there were 16 869 subjects with a mean age of 73 years; the overall adjusted OR between sarcopenia and depression was 1.57 (95% CI: 1.32-1.86). Significant heterogeneity was noted in the adjusted ORs (P < 0.001; I²  = 75.1%).

CONCLUSIONS

The prevalence of depression in patients with sarcopenia was high relatively, and there was a correlation between sarcopenia and depression.

Myokines: Novel therapeutic targets for diabetic nephropathy

With the increasing incidence of diabetic nephropathy (DN), there is an urgent need to find effective DN preventive and therapeutic modalities. It is widely believed that effective exercise is good for health. However, the beneficial role of exercise in kidney disease, especially in DN, and the underlying molecular mechanisms have rarely been reported. Muscle is not only an important motor organ but also an important endocrine organ, secreting a group of proteins called "myokines" into the blood circulation. Circulating myokines then move to various target organs to play different biological roles. In this review, we summarize the currently known myokines and the progress in research relating them to DN and discuss its potential as a therapeutic target for DN.

LPS-induced inflammatory response and apoptosis are mediated by Fra-1 upregulation and binding to YKL-40 in A549 cells

Acute respiratory distress syndrome (ARDS) is a multifactorial syndrome that leads to increased morbidity and mortality in infants and children. The identification of novel biomarkers is critical for the treatment of ARDS. The present study aimed to investigate the effects of chitinase-3-like-1 protein (CHI3L1 or YKL-40) in an in vitro model of ARDS and to explore the potential underlying mechanisms. The in vitro model of ARDS was established in A549 alveolar epithelial type II cells, which were treated by lipopolysaccharide (LPS) to induce inflammation. Transfection was performed to alter YKL-40 expression. The mRNA and protein expression of YKL-40 was determined using reverse transcription-quantitative PCR and western blotting, respectively. Cell Counting Kit-8 and TUNEL assays were used to evaluate the cell viability and apoptosis, respectively. The production of cytokines was evaluated using specific ELISA kits. The relationship between YKL-40 and Fos-related antigen 1 (Fra-1) was verified using luciferase reporter and chromatin immunoprecipitation assays. The expression of the apoptotic proteins was detected using western blotting. The expression levels of YKL-40 and Fra-1 were increased in LPS-treated A549 cells. Higher levels of pro-inflammatory cytokines and induction of cell apoptosis were observed in LPS-treated A549 cells compared with the control. YKL-40 knockdown in LPS-treated A549 cells significantly decreased the production of pro-inflammatory cytokines and reduced cell apoptosis, whereas it concomitantly caused upregulation of Bax and downregulation of Bcl-2, cleaved caspase-3 and cleaved caspase-9. In addition, Fra-1 could directly bind to YKL-40 promoter and regulate its expression level. Overexpression of YKL-40 partly decreased the inhibitory effects of Fra-1 knockdown on the inflammatory response and induction of apoptosis. In summary, the findings from the present study indicated that Fra-1 could bind to YKL-40 and regulate its expression, whereas YKL-40 knockdown could further suppress LPS-induced inflammatory response and apoptosis in A549 cells. These data may provide novel evidence on the diagnosis and therapy of ARDS.

Association of phthalate exposure and airway dysfunction with mediation by serum periostin

BACKGROUND

Phthalates can cause respiratory and immunological disorders. However, little is known about the role of serum periostin and YKL-40 levels in mediating the effects of phthalates. We investigated the mediating role of these biomarkers in the relationship between phthalates and airway dysfunction.

METHODS

A total of 487 children (aged 10-12 years old) were examined. Four high-molecular-weight phthalate (HMWP) [Σ₄ HMWP] metabolites and 3 low-molecular-weight phthalate (LMWP) [Σ₃ LMWP] metabolites in urine samples were measured. Serum periostin and YKL-40 levels were measured. Airway function was measured using impulse oscillometry. A mediation model was used to quantify the mediating effects of periostin and YKL-40 on airway dysfunction.

RESULTS

After adjustment for height, gender, BMI z-score, aeroallergen sensitization, secondary smoking, and vitamin D level, the level of urinary Σ₃ LMWP metabolites was significantly associated with respiratory system resistance at 5 Hz (Rrs5; adjusted β: 0.020, 95% CI: 0.005-0.034; p = .010). The levels of urinary Σ₄ HMWP and Σ₃ LMWP metabolites were significantly associated with periostin level, but not with YKL-40 level. In addition, the periostin level was associated with Rrs5 (adjusted β: 0.048, 95% CI: 0.015-0.081; p = .005) and Rrs20-5 (adjusted β: 0.040, 95% CI: 0.011-0.069; p = .007). Serum periostin level had a significant effect in mediating the relationship between Σ₃ LMWP and Rrs5 (13.9%, 95% CI: 10.7-77.0; p < .001).

CONCLUSION

Exposure to LMWPs was significantly associated with airway dysfunction, and this effect was partially attributable to increased serum periostin level.

The Relationship Between Serum YKL-40 Levels on Admission and Stroke-Associated Pneumonia in Patients with Acute Ischemic Stroke

Background

Stroke-associated pneumonia (SAP) is a standout complication after acute ischemic stroke (AIS), with a prevalence of 7–38%. The aim of this prospective study was to investigate the relationship between serum YKL-40 levels at admission and SAP.

Methods

Between August 2020 and February 2021, consecutive AIS patients from two centers were enrolled prospectively. Serum YKL-40 concentrations were measured via enzyme-linked immunosorbent assay. We performed logistic regression analyses to explore the relationship between YKL-40 and SAP. Receiver operating characteristic curve was also used to assess the predictive ability of YKL-40 in predicting SAP.

Results

Ultimately, a total of 511 AIS patients were recruited. Multivariate logistic regression analysis showed that YKL-40 was independently related to SAP, whether as a continuous variable or as quartiles (P=0.001). The area under curve of YKL-40 to predict SAP was 0.765. The optimal cutoff value of YKL-40 as a predictor of SAP was determined to be 206.4 ng/mL, where the sensitivity was 63.1% and the specificity was 82.0%.

Conclusion

Our study demonstrated that YKL-40 might be considered as a useful biomarker to predict SAP in AIS patients.

The magnitude of airway remodeling is not altered by distinct allergic inflammatory responses in BALB/c versus C57BL/6 mice but matrix composition differs

Allergic airway inflammation is heterogeneous with variability in immune phenotypes observed across asthmatic patients. Inflammation has been thought to directly contribute to airway remodeling in asthma, but clinical data suggest that neutralizing type 2 cytokines does not necessarily alter disease pathogenesis. Here, we utilized C57BL/6 and BALB/c mice to investigate the development of allergic airway inflammation and remodeling. Exposure to an allergen cocktail for up to 8 weeks led to type 2 and type 17 inflammation, characterized by airway eosinophilia and neutrophilia and increased expression of chitinase-like proteins in both C57BL/6 and BALB/c mice. However, BALB/c mice developed much greater inflammatory responses than C57BL/6 mice, effects possibly explained by a failure to induce pathways that regulate and maintain T-cell activation in C57BL/6 mice, as shown by whole lung RNA transcript analysis. Allergen administration resulted in a similar degree of airway remodeling between mouse strains but with differences in collagen subtype composition. Increased collagen III was observed around the airways of C57BL/6 but not BALB/c mice while allergen-induced loss of basement membrane collagen IV was only observed in BALB/c mice. This study highlights a model of type 2/type 17 airway inflammation in mice whereby development of airway remodeling can occur in both BALB/c and C57BL/6 mice despite differences in immune response dynamics between strains. Importantly, compositional changes in the extracellular matrix between genetic strains of mice may help us better understand the relationships between lung function, remodeling and airway inflammation.

Differential Expression Study of Lysine Crotonylation and Proteome for Chronic Obstructive Pulmonary Disease Combined with Type II Respiratory Failure

Introduction

The modification of lysine crotonylation (Kcr) is another biological function of histone in addition to modification of lysine acetylation (Kac), which may play a specific regulatory role in diseases.

Objectives

This study compared the expression levels of Kcr and proteome between patients with chronic obstructive pulmonary disease (COPD) combined with type II respiratory failure (RF) to study the relationship between Kcr, proteome, and COPD.

Methods

We tested the Kcr and proteome of COPD combined with type II RF and normal control (NC) using croton acylation enrichment technology and liquid chromatography tandem mass spectrometry (LC-MS/MS) with high resolution.

Results

We found that 32 sites of 23 proteins were upregulated and 914 sites of 295 proteins were downregulated. We performed Kyoto Encyclopedia of Genes and Genomes (KEGG), protein domain, and Gene Ontology (GO) analysis on crotonylated protein. In proteomics research, we found that 190 proteins were upregulated and 151 proteins were downregulated. Among them, 90 proteins were both modified by differentially expressed crotonylation sites and differentially expressed in COPD combined with type II RF and NC.

Conclusion

Differentially expressed crotonylation sites may be involved in the development of COPD combined with type II RF. 90 proteins modified by crotonylation and differentially expressed in COPD combined with type II RF can be used as markers for the study of the molecular pathogenesis of COPD combined with type II RF.

Inflammatory profile of induced sputum composition in systemic sclerosis and comparison with healthy volunteers

Systemic sclerosis (SSc) is a potentially serious and disabling connective tissue disease specially in case of interstitial lung disease (SSc-ILD). The aim of our study was to evaluate the potential utility of dosing in the induced sputum (IS) and to compare their levels in SSc-ILD and SSc-nonILD patients, as well as in healthy volunteers (HV). IS and sera values were also compared. In a prospective cross-sectional analysis, we studied the IS and serum provided from 25 SSc patients, 15 SSc-nonILD and 10 SSc-ILD, compared to 25 HV. We analyzed sputum cell composition and quantified in the supernatant and corresponding serum by commercially available immunoassays: IGFBP-1, IGFBP-2, IGFBP-3, TGF-β, IL-8, TNF-α, YKL-40, MMP-7 and MMP-9. Lung function was studied by the determination of FEV-1 (%), FVC (%), DLCO (%) and KCO (%). The IS of SSc patients had a lower weight than HV (p<0.05, p<0.01) without any significant difference with regard to the cellularity. IGFBP-1 (p < 0.0001), TGF-β (p < 0.05), IL-8 (p < 0.05), YKL-40 (p < 0.0001) and MMP-7 (p < 0.01) levels were increased in the IS of SSc patients compared to HV. Only IL-8 serum levels (p < 0.001) were increased in SSc patients compared to HV. Neither in IS nor in serum were observed differences between SSc-ILD and SSc-nonILD patients. Correlations were observed between IS IL-8 levels and FEV-1 (%) (r =  = − 0.53, p < 0.01), FVC (%) (r = − 0.51, p < 0.01) and annualized ∆KCO (%) (r = 0.57, p < 0.05), between IS TGF-β levels and annualized ∆FEV-1 (%) (r =  = − 0.57, p < 0.05), between IS IGFBP-2 levels and annualized ∆KCO (%) (r = 0.56, p < 0.05). Our study showed that SSc patients exhibit raised IS levels of IGFBP-1, TGF-β, IL-8, YKL-40 and MMP-7, molecules known to be involved in lung remodeling and fibrotic process, without any significant difference between SSc-ILD and SSc-nonILD patients. IL-8, TGF-β and IGFBP-2 are correlated with lung function in SSc patients which emphasize clinical relevance. IS analysis represents a new approach to understand lung inflammatory process in SSc patients. A longitudinal study is needed to evaluate their pathophysiological relevance.

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.

High Blood Eosinophil and YKL-40 Levels, as Well as Low CXCL9 Levels, are Associated with Increased Readmission in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Background

Readmission after hospital discharge is common among patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Predictive biomarkers of readmission would facilitate stratification strategies and individualized prognosis. Therefore, this study aimed to investigate the utility of type 2 biomarkers (eosinophils, periostin, and YKL-40) and a type 1 biomarker (CXCL9) in predicting readmission events in patients with AECOPD.

Methods

This is a prospective observational study design. Blood levels of eosinophils, periostin, YKL-40, and CXCL9 were measured at admission. The clinical outcomes were 12-month COPD-related readmission, time to COPD-related readmission, and number of 12-month COPD-related readmissions. These outcomes were analyzed using logistic and Cox regression models and Spearman's rank test.

Results

A total of 123 patients were included, of whom 51 had experienced at least one readmission for AECOPD. High levels of eosinophils (≥200 cells/μL or 2% of the total white blood cell count, adjusted odds ratio [aOR] =3.138, P=0.009) and YKL-40 (≥14.5 ng/mL, aOR =2.840, P=0.015), as well as low CXCL9 levels (≤30.1 ng/mL, aOR =2.551, P=0.028), were associated with an increased COPD-related readmission. The highest relative readmission rate was observed in patients with both high eosinophil and YKL-40 levels. Moreover, high eosinophil and YKL-40 levels were associated with a shorter time to first COPD-related readmission and an increased number of 12-month COPD-related readmissions.

Conclusion

High blood eosinophil and YKL-40 levels, as well as low CXCL9 levels, have predictive utility for the 12-month COPD-related readmission rate. Using eosinophils and YKL-40 together allows more precise identification of patients at high risk of COPD-related readmission.

Circulating microRNA-15b-5p as a biomarker for asthma-COPD overlap

BACKGROUND

It remains unclear how to characterize different subtypes of asthma and chronic obstructive pulmonary disease (COPD). We previously described serum periostin and chitinase-3-like protein 1 (YKL-40) as useful markers for asthma-COPD overlap (ACO). MicroRNAs (miRNAs) are now recognized as markers for identifying the pathophysiological features in several diseases. This study aimed to identify circulating miRNAs that could discriminate patients with ACO from patients with asthma or COPD.

METHODS

This study included two independent cohorts. First, we screened 84 miRNAs for expression levels in patients with ACO (n = 6) or asthma (n = 6) using a quantitative real-time PCR array. The miRNAs showing at least a 2-fold difference in the discovery phase were analyzed in 30 patients each with asthma, COPD, or ACO in the replication phase. The diagnostic accuracy was evaluated using the area under the receiver operating characteristic curve (AUROC).

RESULTS

Nine miRNAs were identified in the discovery phase. Five of these miRNAs (miR-148a-3p, miR-15b-5p, miR-223-3p, miR-23a-3p, and miR-26b-5p) had lower levels in ACO patients and could discriminate between ACO patients and patients with either asthma or COPD. miR-15b-5p was the most accurate miRNA for the discrimination of patients with ACO (AUROC, 0.71). Moreover, the combined assessment of miR-15b-5p, serum periostin, and YKL-40 (AUROC, 0.80) improved diagnostic accuracy for ACO compared with the combined model of periostin and YKL-40 (AUROC, 0.69).

CONCLUSIONS

Circulating miR-15b-5p is a potential marker for identifying patients with ACO. By elucidating the molecular pathways controlled by miRNAs, we may better understand the pathophysiology of ACO.

Pleural biomarkers in diagnostics of malignant pleural effusion: a narrative review

Although cytology and pleural biopsy of pleural effusion (PE) are the gold standards for diagnosing malignant pleural effusion (MPE), these tools’ diagnostic accuracy is plagued by some limitations such as low sensitivity, considerable inter-observer variation and invasiveness. The assessment of PE biomarkers may hence be seen as an objective and non-invasive diagnostic alternative in MPE diagnostics. In this review, we summarize the characteristics and diagnostic accuracy of available PE biomarkers, including carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), carbohydrate antigens 125 (CA125), carbohydrate antigen 19-9 (CA19-9), carbohydrate antigen 15-3 (CA15-3), a fragment of cytokeratin 19 (CYFRA 21-1), chitinase-like proteins (CLPs), vascular endothelial growth factor (VEGF) and its soluble receptor, endostatin, calprotectin, cancer ratio, homocysteine, apolipoprotein E (Apo-E), B7 family members, matrix metalloproteinase (MMPs) and tissue-specific inhibitors of metalloproteinases (TIMPs), reactive oxygen species modulator 1 (Romo1), tumor-associated macrophages (TAMs) and monocytes, epigenetic markers (e.g., cell-free microRNA and mRNA). We summarized the evidence from systematic review and meta-analysis for traditional tumor markers’ diagnostic accuracy. According to the currently available evidence, we conclude that the traditional tumor markers have high specificity (around 0.90) but low sensitivity (around 0.50). The diagnostic accuracy of novel tumor markers needs to be validated by further studies. None of these tumor biomarkers would have sufficient diagnostic accuracy to confirm or exclude MPE when used alone. A multi-biomarker strategy, also encompassing the use of artificial intelligence algorithms, may be a valuable perspective for improving the diagnostic accuracy of MPE.

The inflammatory biomarker YKL-40 is elevated in the serum, but not the sputum, of E-cigarette users

METHODS

We conducted a cross-sectional study of adults between 18 and 55 years old. Inclusion criteria were: exclusive e-cigarette use or cigarette smoking for ≥ 1 year or no history of tobacco use. Participants with a history of pulmonary illness, atopy, medications (except birth control pills), marijuana, and illegal substance use were excluded. Custom Multiplex ELISA was used to measure YKL-40 and other biomarker levels in the serum and induced sputum of the participants. Multivariable linear regression was used to compare the levels of YLK-40 in healthy participants, e-cigarette, and cigarette users after adjusting for age, sex, and BMI.

RESULTS

We recruited 20 healthy controls, 23 cigarette smokers, and 22 exclusive e-cigarette users. Serum YKL-40 (ng/ml) was significantly higher in e-cigarette users (Median 21.2 [IQR 12.1-24.0] ng/ml) when compared to controls (12.2 [IQR 8.7-18.1] ng/ml, p = 0.016) but comparable to cigarette smokers (21.6 [IQR 11.62-51.7] ng/ml, p = 0.31). No significant differences were found in the serum or sputum of the other biomarkers tested.

CONCLUSION

The inflammatory biomarker, YKL-40 is elevated in the serum but not the sputum of e-cigarette users with no reported pulmonary disease. Further research is necessary to characterize this association.

Associations of plasma YKL-40 concentrations with heel ultrasound parameters and bone turnover markers in the general adult population

OBJECTIVE

YKL-40, also known as chitinase-3-like protein 1, is a new proinflammatory biomarker, that might play a role in tissue remodeling and bone resorption. Here we evaluated the associations of the YKL-40 plasma concentration with heel ultrasound parameters and bone turnover markers (BTMs) in adult men and women from the general population. We tested for a causal role of YKL-40 on bone metabolism using published single nucleotide polymorphisms (SNPs) with consequences for YKL-40 expression and function.

METHODS

Data were obtained from two population-based cohorts: the Study of Health in Pomerania (SHIP) and SHIP-Trend. Quantitative ultrasound (QUS) measurements at the heel were performed and bone turnover was assessed by measurement of intact amino-terminal propeptide of type I procollagen (PINP) and carboxy-terminal telopeptide of type I collagen (CTX). Associations between the YKL-40 plasma concentration and the QUS-based parameters, bone turnover marker (BTM) concentrations and 44 SNPs, including the lead SNP rs4950928, were evaluated in 382 subjects. Furthermore, we assessed the associations between the same SNPs and the QUS-based parameters (n = 5777) or the BTM concentrations (n = 7190).

RESULTS

Sex-specific linear regression models adjusted for a comprehensive panel of interfering covariantes revealed statistically significant inverse associations between YKL-40 and all QUS-based parameters as well as positive associations with CTX in women. The rs4950928 polymorphism was associated with YKL-40 in men and women but none of the tested SNPs was associated with the QUS-based parameters or the BTMs after correction for multiple testing.

CONCLUSIONS

Plasma YKL-40 concentrations are associated with QUS-based parameters as well as CTX concentrations in women but these associations are probably not causal.

Relationships between increased circulating YKL-40, IL-6 and TNF-α levels and phenotypes and disease activity of primary Sjögren's syndrome

BACKGROUND

There is now no single score or marker useful for evaluating disease activity of primary Sjögren's syndrome (pSS). This study was designed to explore the associations of circulating YKL-40, interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) with systemic activity and phenotypes of pSS.

METHODS

This study included 58 pSS patients and 30 healthy controls (HC). The sera were measured by multiplex immunoassay for YKL-40, IL-6 and TNF-α concentrations. The disease activity of pSS patients was evaluated by European league against rheumatism (EULAR) SS disease activity index (ESSDAI). Local severity was assessed in accordance with the Tarpley score.

RESULTS

Serum YKL-40, IL-6 and TNF-α levels significantly elevated in pSS patients compared with those in HC (all P < 0.001). These cytokines correlated with ESSDAI, ESR, CRP, and IgG (all P < 0.05). Serum YKL-40 level correlated markedly with age (r = 0.405, P = 0.002), neutrophil count (r = 0.399, P = 0.002) and neutrophil-to-lymphocyte ratio (NLR) (r = 0.401, P = 0.002), while IL-6 did weakly with NLR (r = 0.296, P = 0.024) and C3 (r = 0.288, 0.036). Serum levels of all three cytokines were substantially lower in patients with eye/mouth dryness vs. those without (all P < 0.05). Additionally, patients with pulmonary, renal involvement or anemia had remarkably higher concentrations of YKL-40 (all P < 0.05), while those with leukocytopenia had lower levels (P = 0.01). Fever or anemia patients showed higher serum concentrations of IL-6 (both P < 0.05), while serum levels of TNF-α were much higher in patients with presence of ANA, anti-SSA or anti-SSB antibodies (All P < 0.05). Serum IL-6 level correlated strongly with YKL-40 (r = 0.452, P < 0.001) and TNF-α (r = 0.743, P < 0.001) in pSS patients. A significant correlation was also found between YKL-40 and TNF-α (r = 0.308, P = 0.022) .

CONCLUSION

The circulating YKL-40, IL-6 and TNF-α levels increase in pSS, and all of them are significantly correlated with indicators (ESSDAI, ESR, CRP, and IgG) for systemic inflammation of pSS. Each cytokine is separately associated with specific pSS phenotype.

Status and prospects: personalized treatment and biomarker for airway remodeling in asthma

Airway remodeling, as a major characteristic of bronchial asthma, is critical to the progression of this disease, whereas it is of less importance in clinical management. Complying with the current stepwise treatment standard for asthma, the choice of intervention on the clinical status is primarily determined by the patient’s treatment response to airway inflammation. However, a considerable number of asthmatic patients, especially severe asthmatic subjects, remain uncontrolled though they have undergone fortified anti-inflammation treatment. In the past few years, a growing number of biologics specific to asthma phenotypes have emerged, bringing new hope for patients with refractory asthma and severe asthma. While at the same time, the effect of airway remodeling on asthma treatment has become progressively prominent. In the era of personalized treatment, it has become one of the development directions for asthma treatment to find reliable airway remodeling biomarkers to assist in asthma phenotypes classification, and to further combine multiple phenotypes to accurately treat patients. In the present study, the research status of airway remodeling in asthma is reviewed to show the basis for classifying and treating such disease. Besides, several selected airway remodeling biomarkers and possibility to use them in individual treatment are discussed as well. This study considers that continuously optimized mechanisms and emerging biomarkers for airway remodeling in the future may further support individual therapy for asthma patients.

Role of Type2 Inflammatory Biomarkers in Chronic Obstructive Pulmonary Disease

Airway inflammation in chronic obstructive pulmonary disease (COPD) is typically thought to be driven by Type1 immune responses, while Type2 inflammation appears to be present in definite proportions in the stable state and during exacerbations. In fact, some COPD patients showed gene expression of Type2 inflammation in the airway, and this subset was associated with the inhaled corticosteroid (ICS) response. Interestingly enough, the relationship between COPD and diseases associated with Type2 inflammation from the perspective of impaired lung development is increasingly highlighted by recent epidemiologic studies on the origin of COPD. Therefore, many researchers have shown an interest in the prevalence and the role of existent Type2 biomarkers such as sputum and blood eosinophils, exhaled nitric oxide fraction, and atopy, not only in asthma but also in COPD. Although the evidence about Type2 biomarkers in COPD is inconsistent and less robust, Type2 biomarkers have shown some potential when analyzing various clinical outcomes or therapeutic response to ICS. In this article, we review the existent and emerging Type2 biomarkers with clinically higher applicability in the management of COPD.

Chitinase 3-like 1 polymorphisms and risk of chronic obstructive pulmonary disease and asthma in a Chinese population

BACKGROUND

Chitinase 3-like 1 (CHI3L1) plays an important role in airway inflammation and tissue remodeling; however, its pathogenic role in lung diseases remains unclear. In the present study, we investigated whether CHI3L1 polymorphisms are associated with the risk of chronic obstructive pulmonary disease (COPD) and asthma in a Chinese population.

METHODS

We detected seven single nucleotide polymorphisms in CHI3L1 among 361 patients and 527 age- and sex-matched control subjects. We analysed genotype and allele distributions using Stata software (StataCorp,CollegeStation,TX,USA). We used haplotype disease analysis and haplotype phenotype analysis to assess the relationship between seven polymorphisms and the risk of COPD and asthma.

RESULTS

The results showed significant differences between controls and patients with COPD/asthma in the genotype distributions of the polymorphism rs4950928. Additionally, significant differences were observed in the genotype and allele distributions of rs10399805 and rs10399931 between COPD patients and controls. Moreover, the frequencies of haplotype G-G-T-G-T-C-G, G-G-T-G-T-C-C and G-A-T-G-T-C-G (alleles of rs12141494, rs7542294, rs880633, rs10399805, rs10399931, rs946261 and rs4950928, respectively) were significantly higher in patients with COPD. Consideration of the haplotypes of these seven single nucleotide polymorphisms in CHI3L1 in asthma patients revealed a significant association with homocysteine levels (p < 0.001).

CONCLUSIONS

Our findings suggest that the CHI3L1 polymorphisms rs4950928, rs10399805 and rs10399931 can be used as genetic markers for predicting COPD and asthma risk in the Chinese population.

Aging-associated genes TNFRSF12A and CHI3L1 contribute to thyroid cancer: An evidence for the involvement of hypoxia as a driver

The prevalence of thyroid cancer (TC) is high in the elderly. The present study was based on the hypothesis that genes, which have increased activity with aging, may play a role in the development of TC. A large-scale literature-based data analysis was conducted to explore the genes that are implicated in both TC and aging. Subsequently, a mega-analysis of 16 RNA expression datasets (1,222 samples: 439 healthy controls, and 783 patients with TC) was conducted to test a set of genes associated with aging but not TC. To uncover a possible link between these genes and TC, a functional pathway analysis was conducted, and the results were validated by analysis of gene co-expression. A multiple linear regression (MLR) model was employed to study the possible influence of sample size, population region and study age on the gene expression levels in TC. A total of 262 and 816 genes were identified to have increased activity with aging and TC, respectively; with a significant overlap of 63 genes (P<3.82×10⁻³⁵). The mega-analysis revealed two aging-associated genes (CHI3L1 and TNFRSF12A) to be significantly associated with TC (P<2.05×10⁻⁸), and identified the association with multiple hypoxia-driven pathways through functional pathway analysis, also confirmed by the co-expression analysis. The MLR analysis identified population region as a significant factor contributing to the expression levels of CHI3L1 and TNFRSF12A in TC samples (P<3.24×10⁻⁴). The determination of genes that promote aging was warranted due to their possible involvement in TC. The present study suggests CHI3L1 and TNFRSF12A as novel common risk genes associated with both aging and TC.

Evolving Concepts in Chronic Obstructive Pulmonary Disease Blood-Based Biomarkers

In recent years, there has been a great deal of interest in the identification and validation of blood-based biomarkers for clinical use in chronic obstructive pulmonary disease (COPD). We now have panels of blood biomarkers that potentially hold great promise as they show statistically significant associations with COPD, but biomarkers for the diagnosis of COPD remain elusive. In fact, they are yet to demonstrate sufficient accuracy to be accepted in clinical use, and many are not specific to COPD but more related to inflammation (e.g. interleukin-6) or associated with other chronic diseases such as diabetes (e.g. soluble receptor for advanced glycation endproducts [sRAGE]). Although no single blood-based biomarker has demonstrated clinical utility for either the diagnosis or progression of COPD, it has been suggested that combinations of individual markers may provide important diagnostic or prognostic information; however, the interpretation of COPD biomarker results still requires thought and many questions remain unanswered.

Urinary cell cycle arrest biomarkers and chitinase 3-like protein 1 (CHI3L1) to detect acute kidney injury in the critically ill: a post hoc laboratory analysis on the FINNAKI cohort

Background

Acute kidney injury (AKI) is a frequently occurring syndrome in critically ill patients and is associated with worse outcomes. Biomarkers allow early identification and therapy of AKI which may improve outcomes. Urine chitinase 3-like protein 1 (uCHI3L1) was recently identified as a promising urinary biomarker for AKI. In this multicenter study, we evaluated the diagnostic performance for AKI stage 2 or greater of uCHI3L1 in comparison with the urinary cell cycle arrest biomarkers urinary tissue inhibitor of metalloproteinases-2 (TIMP-2)•insulin-like growth factor-binding protein 7 (IGFBP7) measured by NephroCheck Risk®.

Methods

Post hoc laboratory study of the prospective observational FINNAKI study. Of this cohort, we included patients with stored admission urine samples and availability of serum creatinine at day 1 of admission. Patients who already had AKI stage 2 or 3 at ICU admission were excluded. AKI was defined and staged according to the KDIGO definition and staging system. The primary endpoint was AKI stage 2 or 3 at day 1. Biomarker performance was assessed by the area under the curve of the receiver operating characteristic curve (AUC). We assessed individual performance and different combinations of urine biomarkers.

Results

Of 660 included patients, 49 (7.4%) had AKI stages 2–3 at day 1. All urine biomarkers were increased at admission in AKI patients. All biomarkers and most combinations had AUCs < 0.700. The combination uCHI3L1•TIMP-2 was best with a fair AUC of 0.706 (0.670, 0.718). uCHI3L1 had a positive likelihood ratio (LR) of 2.25 which was comparable to that of the NephroCheck Risk® cutoff of 2.0, while the negative LR of 0.53 was comparable to that of the NephroCheck Risk® cutoff of 0.3.

Conclusions

We found that uCHI3L1 and NephroCheck Risk® had a comparable diagnostic performance for diagnosis of AKI stage 2 or greater within a 24-h period in this multicenter FINNAKI cohort. In contrast to initial discovery and validation studies, the diagnostic performance was poor. Possible explanations for this observation are differences in patient populations, proportion of emergency admissions, proportion of functional AKI, rate of developing AKI, and observation periods for diagnosis of AKI.

Biomarkers for chronic obstructive pulmonary disease diagnosis and progression: insights, disappointments and promise

PURPOSE OF REVIEW

This article reviews the status of biomarkers useful in the diagnosis and progression of chronic obstructive pulmonary disease (COPD). Biomarkers have been the focus of a great deal of COPD-related research in recent years, although useful markers in these specific arenas remain elusive.

RECENT FINDINGS

No biomarker other than lung function has been shown to be useful, to date, for the diagnosis of COPD. The best blood-based biomarkers for the progression of COPD may involve combinations of individual markers, such as CC16, fibrinogen and sRAGE. New imaging metrics, such as central airway collapse, pulmonary vascular changes and central airway branch variation, may be able to provide valuable prognostic and information, although these remain confined to research applications.

SUMMARY

Blood-based biomarkers for diagnosing and determining the progression of COPD remain disappointingly elusive. Although there have been some advances in nonblood-based markers, such as those from imaging, exhaled breath or physiologic assessment, these remain limited, for the most part, to research applications. Moving toward better markers that could be used in clinical application in the screening and diagnosis of COPD that could also provide prognostic information remains an important goal of research.

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.

MicroRNA‑30a‑5p promotes proliferation and inhibits apoptosis of human pulmonary artery endothelial cells under hypoxia by targeting YKL‑40

Pulmonary arterial hypertension (PAH) is a fatal and currently incurable cardiopulmonary disease. Numerous microRNAs (miRNAs) serve important roles in the development of PAH. While the expression of miR-30a-5p was downregulated in the lung tissue of rats in a pulmonary hypertension rat model, the expression pattern and function of miR-30a-5p in human PAH remain unclear. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to examine miR-30a-5p and chitinase-3-like protein 1 (YKL-40) mRNA expression levels. The expression levels of YKL-40 and apoptosis-associated proteins were measured by western blot analysis. Cell proliferation assays and flow cytometry analysis were performed to examine cell proliferation and apoptosis, respectively. The association between miR-30a-5p and YKL-40 was determined by a luciferase reporter assay, RT-qPCR and western blot analysis. The relative expression levels of miR-30a-5p in plasma were increased in patients with PAH [median=13.23 (25th percentile=6.388, 75th percentile=21.91)] compared with normal controls [median=2.25 (25th percentile=1.4, 75th percentile=3.7). The expression of miR-30a-5p was significantly downregulated while the protein expression of YKL-40 was significantly upregulated in hypoxia-induced human pulmonary artery endothelial cells (HPAECs) when compared with the hypoxia-induced group at 0 h. miR-30a-5p overexpression promoted HPAEC growth and inhibited apoptosis of HPAECs under hypoxia. A miR-30a-5p mimic decreased the luciferase activity of a luciferase reporter construct containing YKL-40 3′-untranslated region and also decreased YKL-40 protein expression. YKL-40 overexpression partly alleviated the effects of miR-30a-5p upregulation on proliferation and apoptosis of HPAECs under hypoxia. In conclusion, the data indicated that miR-30a-5p promoted cell growth and inhibited apoptosis of HPAECs under hypoxia by targeting YKL-40. Therefore, the miR-30a-5p/YKL-40 axis may provide a potential target for the development of novel PAH therapies.

Association between the mannose-binding lectin (MBL)-2 gene variants and serum MBL with pulmonary tuberculosis: An update meta-analysis and systematic review

In recent years, many studies have demonstrated that the MBL-2 gene polymorphisms may be associated with pulmonary tuberculosis (PTB) susceptibility. Moreover, some studies have shown that serum MBL levels were influenced by the MBL-2 gene polymorphisms and that it plays an important role in tuberculosis infection. However, the results of these studies were inconsistent and underpowered. The current meta-analysis and systematic review aimed to evaluate the association between the MBL-2 gene polymorphisms and serum MBL levels with PTB. Finally, 30 eligible articles were included in the study. The overall results indicated that the MBL-2 rs1800450 (54 A/B) and rs5030737 (52 A/D) polymorphisms were risk factors for PTB, but the MBL-2 rs1800451 (57 A/C) and rs7095891 (+4 P/Q) polymorphisms as protective factors against PTB. No associations were found in the other three polymorphisms (exon 1, rs7096206 (-221 X/Y), and rs11003125 (-550 H/L) of the MBL-2 gene. In addition, we could not detect any significant differences between haplotypes among PTB patients and healthy controls. More important, the meta-analysis results indicated that the serum MBL levels in patients with PTB were significantly lower than those in healthy controls (SMD = 0.43, 95% CI = 0.33-0.52). This study suggested that the MBL-2 gene polymorphisms may be involved in the pathogenesis of PTB, and serum MBL may be a biomarker for the diagnosis of PTB. More rigorous research is needed in the future to confirm these findings further.

Combined Assessment of Serum Periostin and YKL-40 May Identify Asthma-COPD Overlap

BACKGROUND

Asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) has been proposed as a different diagnosis from asthma and COPD. However, little is known about the role of serum biomarkers in ACO.

OBJECTIVE

To evaluate serum periostin, a type 2 biomarker, and serum chitinase-3-like protein 1 (YKL-40), a useful biomarker for COPD, in Japanese patients with asthma, ACO, or COPD, and investigate the role of these biomarkers in identifying ACO.

METHODS

Subjects included Japanese patients with asthma (n = 177), ACO (n = 115), or COPD (n = 61). Serum periostin, YKL-40, and total IgE, blood eosinophils, and fractional exhaled nitric oxide were measured and compared among the patients.

RESULTS

Serum periostin was high in both asthma and ACO, but not in COPD, whereas serum YKL-40 was high in both COPD and ACO, but not in asthma. Serum periostin levels correlated weakly with eosinophil counts in asthma, ACO, and COPD. Multivariate linear regression analysis revealed that older age, lower body mass index, higher eosinophil counts, higher total IgE, and the absence of the diagnosis of COPD were significantly associated with higher periostin levels. Based on cutoff values derived by receiver operating characteristic analysis (periostin: 55.1 ng/mL; YKL-40: 61.3 ng/mL), patients were classified into high or low groups. The proportion of patients with both high serum periostin and YKL-40 levels was significantly higher in ACO than in asthma or COPD.

CONCLUSIONS

Serum periostin levels were comparable between asthma and ACO, whereas YKL-40 was comparable between ACO and COPD. Combined assessment of serum periostin and YKL-40 may identify ACO.