YKL-40, CCL18 and SP-D predict mortality in patients hospitalized with community-acquired pneumonia

Evaluation of the relationship between YKL-40 level and clinical severity in patients with Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever (CCHF) is a widespread tick-borne viral disease. YKL-40 (also known as chitinase-3-like-1 protein) is an acute phase protein released by various immune cells. The purpose of this study was to investigate the relationship between YKL-40 level and the clinical course and prognosis of CCHF. The study included 78 patients who were admitted to our hospital between April 15 and 30 August 2022 and had a positive polymerase chain reaction test result for CCHF. The patients were divided into two groups, severe and non-severe. In addition, a control group consisting of 22 healthy people was established. Mean serum YKL-40 levels were significantly higher in patients than controls (106.8 ng/mL ± 91.2 and 47.1 ng/mL ± 35.3, respectively; p < 0.001). However, mean YKL-40 levels were also significantly higher in patients with severe CCHF compared to non-severe cases (173.3 ± 112.3 and 67.5 ± 41.7, respectively; p < 0.001). A comparison of the 10 exitus patients and the 68 survivors revealed significantly higher YKL-40 levels in the exitus group (mean: 214.0 ± 139.0 and 92.8 ± 73.6, respectively; p = 0.001). A receiver operating characteristic analysis for YKL-40 levels to distinguish between severe and non-severe patients found an area under the curve of 0.925. YKL-40 levels were measured with a sensitivity of 97% and a specificity of 84% with a cutoff value of 90.7 ng/mL. YKL-40 levels measured at the time of hospital presentation in patients with CCHF can be used as a biomarker for clinical course and prognosis.

Diagnostic Performance of Plasma SP-D, KL-6, and CC16 in Acutely Hospitalised Patients Suspected of Having Community-Acquired Pneumonia-A Diagnostic Accuracy Study

Community-acquired pneumonia is a common cause of acute hospitalisation. Identifying patients with community-acquired pneumonia among patients suspected of having the disease can be a challenge, which causes unnecessary antibiotic treatment. We investigated whether the circulatory pulmonary injury markers surfactant protein D (SP-D), Krebs von den Lungen-6 (KL-6), and Club cell protein 16 (CC16) could help identify patients with community-acquired pneumonia upon acute admission. In this multi-centre diagnostic accuracy study, SP-D, KL-6, and CC16 were quantified in plasma samples from acutely hospitalised patients with provisional diagnoses of community-acquired pneumonia. The area under the receiver operator characteristics curve (AUC) was calculated for each marker against the following outcomes: patients' final diagnoses regarding community-acquired pneumonia assigned by an expert panel, and pneumonic findings on chest CTs. Plasma samples from 339 patients were analysed. The prevalence of community-acquired pneumonia was 63%. AUCs for each marker against both final diagnoses and chest CT diagnoses ranged between 0.50 and 0.56. Thus, SP-D, KL-6, and CC16 demonstrated poor diagnostic performance for community-acquired pneumonia in acutely hospitalised patients. Our findings indicate that the markers cannot readily assist physicians in confirming or ruling out community-acquired pneumonia.

Community-acquired pneumonia: use of clinical characteristics of acutely admitted patients for the development of a diagnostic model - a cross-sectional multicentre study

OBJECTIVES

This study aimed to describe the clinical characteristics of adults with suspected acute community-acquired pneumonia (CAP) on hospitalisation, evaluate their prediction performance for CAP and compare the performance of the model to the initial assessment of the physician.

DESIGN

Cross-sectional, multicentre study.

SETTING

The data originated from the INfectious DisEases in Emergency Departments study and were collected prospectively from patient interviews and medical records. The study included four Danish medical emergency departments (EDs) and was conducted between 1 March 2021 and 28 February 2022.

PARTICIPANTS

A total of 954 patients admitted with suspected infection were included in the study.

PRIMARY AND SECONDARY OUTCOME

The primary outcome was CAP diagnosis assessed by an expert panel.

RESULTS

According to expert evaluation, CAP had a 28% prevalence. 13 diagnostic predictors were identified using least absolute shrinkage and selection operator regression to build the prediction model: dyspnoea, expectoration, cough, common cold, malaise, chest pain, respiratory rate (>20 breaths/min), oxygen saturation (<96%), abnormal chest auscultation, leucocytes (<3.5×109/L or >8.8×109/L) and neutrophils (>7.5×109/L). C reactive protein (<20 mg/L) and having no previous event of CAP contributed negatively to the final model. The predictors yielded good prediction performance for CAP with an area under the receiver-operator characteristic curve (AUC) of 0.85 (CI 0.77 to 0.92). However, the initial diagnosis made by the ED physician performed better, with an AUC of 0.86 (CI 84% to 89%).

CONCLUSION

Typical respiratory symptoms combined with abnormal vital signs and elevated infection biomarkers were predictors for CAP on admission to an ED. The clinical value of the prediction model is questionable in our setting as it does not outperform the clinician's assessment. Further studies that add novel diagnostic tools and use imaging or serological markers are needed to improve a model that would help diagnose CAP in an ED setting more accurately.

TRIAL REGISTRATION NUMBER

NCT04681963.

Circulating markers of neutrophil activation and lung injury in pediatric pneumonia in low-resource settings

Diagnostic biomarkers for childhood pneumonia could guide management and improve antibiotic stewardship in low-resource settings where chest x-ray (CXR) is not always available. In this cross-sectional study, we measured chitinase 3-like protein 1 (CHI3L1), surfactant protein D (SP-D), lipocalin-2 (LCN2), and tissue inhibitor of metalloproteinases-1 (TIMP-1) in Ugandan children under the age of five hospitalized with acute lower respiratory tract infection. We determined the association between biomarker levels and primary end-point pneumonia, indicated by CXR consolidation. We included 89 children (median age 11 months, 39% female). Primary endpoint pneumonia was present in 22 (25%). Clinical signs were similar in children with and without CXR consolidation. Broad-spectrum antibiotics (ceftriaxone) were administered in 83 (93%). Levels of CHI3L1, SP-D, LCN2 and TIMP-1 were higher in patients with primary end-point pneumonia compared to patients with normal CXR or other infiltrates. All markers were moderately accurate predictors of primary end-point pneumonia, with area under receiver operator characteristic curves of 0.66-0.70 (p<0.05 for all markers). The probability of CXR consolidation increased monotonically with the number of markers above cut-off. Among 28 patients (31%) in whom all four markers were below the cut-off, the likelihood ratio of CXR consolidation was 0.11 (95%CI 0.015 to 0.73). CHI3L1, SP-D, LCN2 and TIMP-1 were associated with CXR consolidation in children with clinical pneumonia in a low-resource setting. Combinations of quantitative biomarkers may be useful to safely withhold antibiotics in children with a low probability of bacterial infection.

Optimizing Screening for Early Disease Detection in Familial Pulmonary Fibrosis (FLORIS): A Prospective Cohort Study Design

Background: Familial pulmonary fibrosis (FPF) can be defined as pulmonary fibrosis in two or more first-degree family members. The first-degree family members of FPF patients are at high risk of developing FPF and are eligible for screening. Reproducible studies investigating risk factors for disease are much needed. Methods: Description of the screening study protocol for a single-center, prospective cohort study; the study will include 200 asymptomatic, first-degree family members of patients with FPF who will undergo three study visits in two years. The primary objective is determining the diagnostic value of parameters for detection of early FPF; the secondary objectives are determining the optimal timing of the screening interval and gaining insight into the natural history of early FPF. The presence of interstitial lung disease (ILD) changes on high-resolution computed tomography of the chest is indicative of preclinical ILD; the changes are determined at baseline. The comparison between the group with and without ILD changes is made for clinical parameters (pulmonary function, presence of digital clubbing, presence of Velcro-like crackles, blood count, liver- and kidney-function testing, patient-reported cough and dyspnea score) and exploratory parameters. Discussion: This study will be the first large-size, prospective, longitudinal cohort study for yearly screening of asymptomatic family members of FPF patients investigating the diagnostic value of parameters, including lung function, to detect early FPF. More effective screening strategies could advance early disease detection.

A novel biomarker in acute cholecystitis: YKL-40

BACKGROUND

The lack of a specific biomarker that can be used in the diagnosis of acute cholecystitis, a common cause of admission to the emergency department, delays physician efforts to diagnose and treat these patients. Therefore, the aim of this study was to measure plasma YKL-40 levels and investigate their diagnostic value in patients with acute cholecystitis (AC).

METHODS

This study was carried out between February 2020 and September 2020 in the adult emergency department of a tertiary university hospital. Permission was obtained from the Ethics Committee of Scientific Research on 03/02/2020 with Decision No. 03/16. The study included 80 patients who were diagnosed with acute cholecystitis and 80 healthy volunteers without known chronic diseases.

RESULTS

The median YKL-40 protein level was 798.66 pq/mL in the patient group and 392.45 pq/mL in the control group. A statistically significant difference in YKL-40 protein levels was found between the two groups. YKL-40 protein levels were significantly higher in patients diagnosed with acute cholecystitis than in healthy individuals (p < 0.001). A positive correlation was found between YKL-40 protein levels and ALT, AST, LDH, and GGT levels (r = 0.272, p = 0.015; r = 0.397, p < 0.001; r = 0.386, p < 0.001; and r = 0.264, p = 0.018; respectively).

CONCLUSION

When evaluated together with physical examination, radiological imaging and other laboratory parameters, we think that plasma YKL-40 levels can be used effectively in the diagnosis of acute cholecystitis.

Role of surfactant protein-D in ocular bacterial infection

Purpose

Our review explains the role of surfactant protein D (SP-D) in different kinds of bacterial infection based on its presence in different ocular surface tissues. We discuss the potential role of SP-D against invasion by pathogens, with the aim of identifying new prospects for the possible mechanism of SP-D-mediated immune processes, and the diagnosis, prognosis, or treatment of ocular bacterial infection.

Methods

We reviewed articles about the role of SP-D in various ocular bacterial infections or infection-related ocular diseases through PubMed, Google Scholar, and the Web of Science databases.

Results

SP-D acts as an important immune factor that can resemble molecules in different polymerization states and that defends against pathogen invasion. The increased SP-D production and secretion in tear fluid and the cornea after ocular bacterial infections such as Staphylococcus aureus, Pseudomonas aeruginosa keratitis, and infection-related ocular diseases, was shown to have potential anti-inflammatory effects. The mechanisms of SP-D’s action against ocular bacterial infections include presenting, aggregating, opsonizing, and phagocytizing antigens, as well as regulating anti-bacterial immunity processes, including toll-like receptor-5 (TLR-5) pathway and IL-8 effect, TLR-4 and TLR-2 pathways and other possible ways remained to be elucidated in more detail. The findings demonstrate the potential of SP-D as an important clinical diagnostic biomarker prognosis predictor, and target for ocular immunotherapy.

Conclusion

SP-D participates in invasion by different ocular bacteria and infection-related ocular diseases through multiple immune mechanisms. This finding provides new prospects for the diagnosis, prognosis and treatment of ocular bacterial infection.

Surfactant protein D is a biomarker of influenza-related pediatric lung injury

BACKGROUND

Biomarkers that can risk-stratify children with influenza virus lower respiratory infection may identify patients for targeted intervention. Early elevation of alveolar-related proteins in the bloodstream in these patients could indicate more severe lung damage portending worse outcomes.

METHODS

We used a mouse model of human influenza infection and evaluated relationships between lung pathophysiology and surfactant protein D (SP-D), SP-A, and Club cell protein 16 (CC16). We then measured SP-A, SP-D, and CC16 levels in plasma samples from 94 children with influenza-associated acute respiratory failure (PICFLU cohort), excluding children with underlying conditions explaining disease severity. We tested for associations between levels of circulating proteins and disease severity including the diagnosis of acute respiratory distress syndrome (ARDS), mechanical ventilator, intensive care unit and hospital days, and hospital mortality.

RESULTS

Circulating SP-D showed a greater increase than SP-A and CC16 in mice with increased alveolar-vascular permeability following influenza infection. In the PICFLU cohort, SP-D was associated with moderate-severe ARDS diagnosis (p = 0.01) and with mechanical ventilator (r = 0.45, p = 0.002), ICU (r = 0.44, p = 0.002), and hospital days (r = 0.37, p = 0.001) in influenza-infected children without bacterial coinfection. Levels of SP-D were lower in children with secondary bacterial pneumonia (p = 0.01) and not associated with outcomes. CC16 and SP-A levels did not differ with bacterial coinfection and were not consistently associated with severe outcomes.

CONCLUSIONS

SP-D has potential as an early circulating biomarker reflecting a degree of lung damage caused directly by influenza virus infection in children. Secondary bacterial pneumonia alters SP-D biomarker performance.

Surfactant protein D: a predictor for severity of community-acquired pneumonia in children

BACKGROUND

Surfactant protein D (SP-D) is a promising biomarker proposed for the prediction of community-acquired pneumonia (CAP) severity. Therefore, we aimed to assess the role of SP-D in the prediction of CAP severity in pediatric patients.

METHODS

A prospective cohort study was carried out at the Pediatric Intensive Care Unit (PICU) and wards of Menoufia University Hospital. We recruited 112 children admitted into wards with pneumonia (simple pneumonia) and 68 children admitted into PICU with severe pneumonia (PICU admitted). World Health Organization (WHO) classification and mortality predictive scores were calculated to determine the severity of pneumonia for the two groups, including the Pediatric Respiratory Severity Score (PRESS) and the Predisposition, Insult, Response, and Organ dysfunction modified Score (PIROm). SP-D was measured at admission.

RESULTS

The SP-D level was significantly lower in patients with simple pneumonia than in patients with severe pneumonia (P < 0.001). SP-D was significantly higher among children with severe pneumonia, as determined by WHO, PRESS, and PIROm (P = 0.001). SP-D was significantly higher among children with mechanical ventilation, shock, hypoxia, sepsis, and mortality. Receiver operating characteristic curve analysis for SP-D showed that the area under the curve was 0.741 (P value < 0.001), with a sensitivity of 85.3% and a specificity of 44.6%.

CONCLUSIONS

Serum SP-D level has a predictive value for the detection of community-acquired pneumonia severity in children.

IMPACT

SP-D is a good predictor for the detection of CAP severity in hospitalized children. SP-D was correlated with severity scores and was associated with indicators of CAP severity, including mechanical ventilation, shock, hypoxia, sepsis, and mortality.

[Value of serum YKL-40 in the diagnosis of anti-MDA5-positive patients with dermatomyositis complicated with severe pulmonary injury]

OBJECTIVE

To investigate the value of serum and bronchoalveolar lavage fluid (BALF) chitinase-3-like-1 protein (YKL-40) in the diagnosis of anti-melanoma differentiation-associated gene 5 (MDA5)-positive dermatomyositis (DM) patients complicated with serious pulmonary injury, including rapidly progressive interstitial lung disease (RP-ILD) and pulmonary infection.

METHODS

Anti-MDA5 antibodies positive patients with DM who were hospitalized in the Department of Rheumatology of China-Japan Friendship Hospital from 2013 to 2018 were involved in this study. Demographic information, clinical, laboratory and imaging data were retrospectively collected. ELISA was used to detect the serum and BALF levels of YKL-40. The receiver operating characteristic (ROC) curve was drawn, and the area under ROC curve (AUC) was used to evaluate the diagnostic value of serum YKL-40 for pulmonary injury.Interstitial lung disease (ILD) was confirmed by chest high-resolution CT (HRCT). RP-ILD was defined as progressive respiratory symptoms such as dyspnea and hypoxemia within 3 months, and/or deterioration of interstitial changes or appearace of new pulmonary interstitial lesions on chest HRCT. Pulmonary infection was considered as positive pathogens detected in qualified sputum, blood, bronchoalveolar lavage fluid or lung biopsy specimens.

RESULTS

A total of 168 anti-MDA5-positive DM patients including 108 females and 60 males were enrolled in the study. Of these patients, 154 had ILD, and 66(39.3%) of them presented RP-ILD. Seventy patients with pulmonary infection were confirmed by etiology. In the patients with RP-ILD, 39 (59.1%) of them were complicated with pulmonary infection. While only 31 cases(30.4%) had pulmonary infection in the non-RP-ILD patients. The incidence of pulmonary infection in the patients with RP-ILD was significantly higher than that of those with non-RP-ILD (P < 0.001). The serum YKL-40 levels in the RP-ILD patients with pulmonary infection were the highest compared with RP-ILD without pulmonary infection, non-RP-ILD with pulmonary infection and non-RP-ILD without pulmonary infection groups among all the patients [83 (42-142) vs. 42 (21-91) vs. 43 (24-79) vs. 38 (22-69), P < 0.01].The sensitivity, specificity and AUC of serum YKL-40 in the diagnosis of RP-ILD complicated with pulmonary infection were 75%, 67%, and 0.72, respectively. The AUC of diagnosed of anti-MDA5 positive DM patients complicated with RP-ILD and pulmonary infection was higher than that of patients complicated with only RP-ILD and only pulmonary infection (0.72 vs. 0.54 and 0.55, Z=2.10 and 2.11, P < 0.05).

CONCLUSION

The prognosis of anti-MDA5-positive DM patients with RP-ILD and pulmonary infection were poor. Serum YKL-40 level can be used as a helpful tool for the diagnosis of coexistence of these conditions in the patients.

A literature review of severity scores for adults with influenza or community-acquired pneumonia - implications for influenza vaccines and therapeutics

Influenza vaccination and antiviral therapeutics may attenuate disease, decreasing severity of illness in vaccinated and treated persons. Standardized assessment tools, definitions of disease severity, and clinical endpoints would support characterizing the attenuating effects of influenza vaccines and antivirals. We review potential clinical parameters and endpoints that may be useful for ordinal scales evaluating attenuating effects of influenza vaccines and antivirals in hospital-based studies. In studies of influenza and community-acquired pneumonia, common physiologic parameters that predicted outcomes such as mortality, ICU admission, complications, and duration of stay included vital signs (hypotension, tachypnea, fever, hypoxia), laboratory results (blood urea nitrogen, platelets, serum sodium), and radiographic findings of infiltrates or effusions. Ordinal scales based on these parameters may be useful endpoints for evaluating attenuating effects of influenza vaccines and therapeutics. Factors such as clinical and policy relevance, reproducibility, and specificity of measurements should be considered when creating a standardized ordinal scale for assessment.

Associations between YKL-40 and markers of disease severity and death in patients with necrotizing soft-tissue infection

Background

Necrotizing soft-tissue infection (NSTI) is a severe and fast-progressing bacterial infection. Prognostic biomarkers may provide valuable information in treatment guidance and decision-making, but none have provided sufficient robustness to have a clinical impact. YKL-40 may reflect the ongoing pathological inflammatory processes more accurately than traditional biomarkers as it is secreted by the activated immune cells, but its prognostic yields in NSTI remains unknown. For this purpose, we investigated the association between plasma YKL-40 and 30-day mortality in patients with NSTI, and assessed its value as a marker of disease severity.

Methods

We determined plasma YKL-40 levels in patients with NSTI (n = 161) and age-sex matched controls (n = 65) upon admission and at day 1, 2 and 3.

Results

Baseline plasma YKL-40 was 1191 ng/mL in patients with NSTI compared with 40 ng/mL in controls (p < 0.001). YKL-40 was found to be significantly higher in patients with septic shock (1942 vs. 720 ng/mL, p < 0.001), and in patients receiving renal-replacement therapy (2382 vs. 1041 ng/mL, p < 0.001). YKL-40 correlated with Simplified Acute Physiology Score II (Rho 0.33, p < 0.001). Baseline YKL-40 above 1840 ng/mL was associated with increased risk of 30-day mortality in age-sex-comorbidity adjusted analysis (OR 3.77, 95% CI; 1.59–9.24, p = 0.003), but after further adjustment for Simplified Acute Physiology Score II no association was found between YKL-40 and early mortality.

Conclusion

High plasma YKL-40 to be associated with disease severity, renal-replacement therapy and risk of death in patients with NSTI. However, YKL-40 is not an independent predictor of 30-day mortality.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06760-x.

Seeking diagnostic and prognostic biomarkers for childhood bacterial pneumonia in sub-Saharan Africa: study protocol for an observational study

INTRODUCTION

Clinically diagnosed pneumonia in children is a leading cause of paediatric hospitalisation and mortality. The aetiology is usually bacterial or viral, but malaria can cause a syndrome indistinguishable from clinical pneumonia. There is no method with high sensitivity to detect a bacterial infection in these patients and, as result, antibiotics are frequently overprescribed. Conversely, unrecognised concomitant bacterial infection in patients with malarial infections occur with omission of antibiotic therapy from patients with bacterial infections. Previously, we identified two combinations of blood proteins with 96% sensitivity and 86% specificity for detecting bacterial disease. The current project aimed to validate and improve these combinations by evaluating additional biomarkers in paediatric patients with clinical pneumonia. Our goal was to describe combinations of a limited number of proteins with high sensitivity and specificity for bacterial infection to be incorporated in future point-of-care tests. Furthermore, we seek to explore signatures to prognosticate clinical pneumonia.

METHODS AND ANALYSIS

Patients (n=900) aged 2-59 months presenting with clinical pneumonia at two Gambian hospitals will be enrolled and classified according to criteria for definitive bacterial aetiology (based on microbiological tests and chest radiographs). We will measure proteins at admission using Luminex-based immunoassays in 90 children with definitive and 160 with probable bacterial aetiology, and 160 children classified according to the prognosis of their disease. Previously identified diagnostic signatures will be assessed through accuracy measures. Moreover, we will seek new diagnostic and prognostic signatures through machine learning methods, including support vector machine, penalised regression and classification trees.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the Gambia Government/Medical Research Council Unit The Gambia Joint Ethics Committee (protocol 1616) and the institutional review board of Boston University Medical Centre (STUDY00000958). Study results will be disseminated to the staff of the study hospitals, in scientific seminars and meetings, and in publications.

TRIAL REGISTRATION NUMBER

H-38462.

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.

[Surfactant proteins A and D: role in the pathogenesis of community-acquired pneumonia and possible predictive perspectives]

Community-acquired pneumonia is one of the most common infectious diseases and remains one of the leading causes of death in this group of diseases. Studies of community-acquired pneumonia are extremely relevant for modern clinical practice. One of the important role in the pathogenesis of bacterial, viral, fungal invasion in the system of a human lung system belongs to the pulmonary surfactant, in particular, its proteins SP-A and SP-D. This article reviews the well-known mechanisms of important biological properties of immunomodulatory activity of the proteins SP-A and SP-D in response to microbial infection in the lungs. The mechanisms of participation of surfactant proteins SP-A and SP-D in the cascade of reactions that lead to severe life-threatening complications in community-acquired pneumonia are considered. The use of serum levels of surfactant proteins SP-A and SP-D can help finding new diagnostic and prognostic approaches in patients with community-acquired pneumonia.

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.

Elevated plasma YKL-40 and risk of infectious disease: a prospective study of 94665 individuals from the general population

OBJECTIVES

YKL-40 is an acute phase protein elevated in patients with infectious and inflammatory diseases. We tested the hypothesis that baseline elevated YKL-40 is associated with increased risk of future infectious disease in healthy individuals in the general population.

METHODS

We prospectively followed 94 665 individuals from the Danish general population for up to 23 years and analysed for plasma YKL-40 levels (n = 21 584) and CHI3L1 rs4950928 genotype (n = 94 184). Endpoints were any infection, bacterial pneumonia, urinary tract infection, skin infection, sepsis, diarrhoeal disease, and other infections.

RESULTS

For YKL-40 percentile category 91-100% versus 0-33%, the multifactorially and C-reactive protein (CRP) adjusted hazard ratios were 1.71 (95% confidence interval 1.50-1.96; p 4 × 10^-14) for any infection, 1.97 (1.64-2.37; p 4 × 10^-13) for bacterial pneumonia, 1.62 (1.24-2.11; p 0.002) for urinary tract infection, 1.74 (1.31-2.32; p 2 × 10^-4) for skin infection, 1.76 (1.25-2.46; p 0.004) for sepsis, 1.90 (1.29-2.78; p 0.002) for diarrhoeal disease and 2.71 (1.38-5.35; p 0.01) for other infections. In multifactorially and CRP-adjusted models, a twofold increase in YKL-40 was associated with increased risk of all infectious disease endpoints. Mendelian randomization did not support causality, as CHI3L1 rs4950928 was associated with 94% and 190% higher YKL-40 levels (for CG and CC versus GG genotype), but not with increased risk of any infectious disease endpoint.

DISCUSSION

Baseline elevated plasma YKL-40 was not a cause but a strong marker of increased risk of future infectious diseases in individuals in the general population.

[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.

Biomarkers of Acute Lung Injury The Individualized Approach: for Phenotyping, Risk Stratification and Treatment Surveillance

Do we need biomarkers of lung damage and infection: For what purpose and how should they be used properly? Biomarkers of lung damage can be used for diagnosis, risk stratification/prediction, treatment surveillance and adjustment of targeted therapy. Additionally, novel "omics" methods may offer a completely different and effective way of improving the understanding of pathogenesis of lung damage and a way to develop new candidate lung damage biomarkers. In the current review, we give an overview within the field of acute lung damage of (i) disease mechanism biomarkers, (ii) of "ready to use" evidence-based biomarker-guided lung infection management, (iii) of novel strategies of inflammatory phenotyping and how this can be used to tailor corticosteroid treatment, (iv) a future perspective of where "omics" technologies and mindsets may become increasingly important in developing new strategies for treatment and for understanding the development of acute lung damage.

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.

Clinical Significance of Serum Hemeoxygenase-1 as a New Biomarker for the Patients with Interstitial Pneumonia

Background

Serum hemeoxygenase-1 (HO-1) has been proposed to be a biomarker of lung disease activity and prognosis. The present study aimed at evaluating whether HO-1 could be a useful marker for evaluating disease activity and predicting prognosis in patients with interstitial pneumonia (IP).

Materials and Methods

Serum HO-1 levels of newly diagnosed or untreated patients with IP were measured at hospitalization. We evaluated the relationships between serum HO-1 and other serum biomarkers, high resolution CT (HRCT) findings, and hospital mortality.

Results

Twenty-eight patients with IP, including 14 having an acute exacerbation (AE) and 14 not having an AE, were evaluated. The patients having an AE had significantly higher HO-1 levels than those not having an AE (53.5 ng/mL vs. 24.1 ng/mL; p < 0.001), and the best cut-off level to discriminate between having an AE or not having an AE was 41.6 ng/mL. Serum HO-1 levels were positively correlated with serum levels of surfactant protein-D (r=0.66, p < 0.001) and the ground glass opacity score (calculated from HRCT; r=0.40, p=0.036). Patients who subsequently died in hospital had presented with significantly higher HO-1 levels than those who did not die in hospital (64.8 ng/mL vs. 32.0 ng/mL; p=0.009).

Conclusion

Serum HO-1 may serve as a useful biomarker for detecting AE or predicting hospital mortality in patients with IP.

Chitinase-like proteins as regulators of innate immunity and tissue repair: helpful lessons for asthma?

Chitinases and chitinase-like proteins (CLPs) belong to the glycoside hydrolase family 18 of proteins. Chitinases are expressed in mammals and lower organisms, facilitate chitin degradation, and hence act as host-defence enzymes. Gene duplication and loss-of-function mutations of enzymatically active chitinases have resulted in the expression of a diverse range of CLPs across different species. CLPs are genes that are increasingly associated with inflammation and tissue remodelling not only in mammals but also across distant species. While the focus has remained on understanding the functions and expression patterns of CLPs during disease in humans, studies in mouse and lower organisms have revealed important and overlapping roles of the CLP family during physiology, host defence and pathology. This review will summarise recent insights into the regulatory functions of CLPs on innate immune pathways and discuss how these effects are not only important for host defence and tissue injury/repair after pathogen invasion, but also how they have extensive implications for pathological processes involved in diseases such as asthma.

Course of SP-D, YKL-40, CCL18 and CA 15-3 in adult patients hospitalised with community-acquired pneumonia and their association with disease severity and aetiology: A post-hoc analysis

BACKGROUND AND AIM

SP-D, YKL-40, CCL18 and CA 15-3 are pulmonary markers that have been extensively investigated in different chronic pulmonary diseases. However, in acute pulmonary diseases, such as community-acquired pneumonia (CAP), little is known about the course of these markers and their relationship with the aetiological agent. The aim of this study was to investigate the course of these four markers in CAP and to study influence of disease severity, aetiology and antibiotic use prior to admission on their course.

METHODS

We included 291 adult patients hospitalised with CAP and 20 healthy controls. Measurements were performed in serum of day 0, 2, and 4, and at least 30 days after admission.

RESULTS

Our most important results were: 1) At all time-points, including 30 days after admission, YKL-40 and CCL18 levels were higher in CAP patients compared to healthy controls; and 2) Patients with CAP caused by an intracellular, atypical bacterium had lower YKL-40 and especially CCL18 levels on and during admission in comparison with other or unknown CAP aetiology.

CONCLUSIONS

Our findings suggest that these pulmonary markers could be useful to assess CAP severity and, especially YKL-40 and CCL18 by helping predict CAP caused by atypical pathogens.