Breath Biopsy® to Identify Exhaled Volatile Organic Compounds Biomarkers for Liver Cirrhosis Detection

Background and Aims

The prevalence of chronic liver disease in adults exceeds 30% in some countries and there is significant interest in developing tests and treatments to help control disease progression and reduce healthcare burden. Breath is a rich sampling matrix that offers non-invasive solutions suitable for early-stage detection and disease monitoring. Having previously investigated targeted analysis of a single biomarker, here we investigated a multiparametric approach to breath testing that would provide more robust and reliable results for clinical use.

Methods

To identify candidate biomarkers we compared 46 breath samples from cirrhosis patients and 42 from controls. Collection and analysis used Breath Biopsy OMNI™, maximizing signal and contrast to background to provide high confidence biomarker detection based upon gas chromatography mass spectrometry (GC-MS). Blank samples were also analyzed to provide detailed information on background volatile organic compounds (VOCs) levels.

Results

A set of 29 breath VOCs differed significantly between cirrhosis and controls. A classification model based on these VOCs had an area under the curve (AUC) of 0.95±0.04 in cross-validated test sets. The seven best performing VOCs were sufficient to maximize classification performance. A subset of 11 VOCs was correlated with blood metrics of liver function (bilirubin, albumin, prothrombin time) and separated patients by cirrhosis severity using principal component analysis.

Conclusions

A set of seven VOCs consisting of previously reported and novel candidates show promise as a panel for liver disease detection and monitoring, showing correlation to disease severity and serum biomarkers at late stage.

Exhaled volatile organic compounds and lung microbiome in COPD: a pilot randomised controlled trial

Background

Breath analysis is a burgeoning field, with interest in volatile organic compounds (VOCs) as a noninvasive diagnostic tool or an outcome measure, but no randomised controlled trials (RCTs) have yet evaluated this technology in a clinical trial longitudinally. In a pilot RCT, our exploratory objectives were feasibility of measuring VOCs via multiple techniques, assessing relationships between VOCs and Haemophilus colonisation and whether CXCR2 antagonism with danirixin altered lung microbiome composition in individuals with COPD.

Method

43 participants had VOCs and sputum biomarkers evaluated. VOCs and induced sputum were collected after 6 h of fasting at screening and at days 1, 7 and 14. VOCs were analysed via gas chromatography mass spectrometry (GC-MS), field asymmetric ion mobility spectrometry (FAIMS) and eNose. The primary outcome for these analyses was the relationship between VOCs and Haemophilus abundance determined by 16S rRNA sequencing.

Results

A joint-effects model demonstrated a modest relationship between four exhaled VOCs and Haemophilus relative abundance (R²=0.55) measured only by GC-MS, but not as measured using gas chromtaography FAIMS or eNose. There was considerable variability in absolute quantities of individual VOCs longitudinally.

Conclusions

VOC measurement in clinical trials to identify subsets of COPD is feasible, but assessment of new VOC technologies must include concurrent GC-MS validation. Further work to standardise collection of VOCs and measuring a background or “housekeeper” VOC is required to understand and normalise individual VOC quantities.

VOC measurement in clinical trials to identify COPD subsets is feasible, but assessment of VOC technologies must include concurrent GC-MS validation. Further work to standardise collection of VOCs and measure a background or “housekeeper” VOC is required.https://bit.ly/3BNyKvS

The SARS-CoV-2 viral load in COVID-19 patients is lower on face mask filters than on nasopharyngeal swabs

Face masks and personal respirators are used to curb the transmission of SARS-CoV-2 in respiratory droplets; filters embedded in some personal protective equipment could be used as a non-invasive sample source for applications, including at-home testing, but information is needed about whether filters are suited to capture viral particles for SARS-CoV-2 detection. In this study, we generated inactivated virus-laden aerosols of 0.3–2 microns in diameter (0.9 µm mean diameter by mass) and dispersed the aerosolized viral particles onto electrostatic face mask filters. The limit of detection for inactivated coronaviruses SARS-CoV-2 and HCoV-NL63 extracted from filters was between 10 to 100 copies/filter for both viruses. Testing for SARS-CoV-2, using face mask filters and nasopharyngeal swabs collected from hospitalized COVID-19-patients, showed that filter samples offered reduced sensitivity (8.5% compared to nasopharyngeal swabs). The low concordance of SARS-CoV-2 detection between filters and nasopharyngeal swabs indicated that number of viral particles collected on the face mask filter was below the limit of detection for all patients but those with the highest viral loads. This indicated face masks are unsuitable to replace diagnostic nasopharyngeal swabs in COVID-19 diagnosis. The ability to detect nucleic acids on face mask filters may, however, find other uses worth future investigation.

Pharmacogenomic associations of adverse drug reactions in asthma: systematic review and research prioritisation

A systematic review of pharmacogenomic studies capturing adverse drug reactions (ADRs) related to asthma medications was undertaken, and a survey of Pharmacogenomics in Childhood Asthma (PiCA) consortia members was conducted. Studies were eligible if genetic polymorphisms were compared with suspected ADR(s) in a patient with asthma, as either a primary or secondary outcome. Five studies met the inclusion criteria. The ADRs and polymorphisms identified were change in lung function tests (rs1042713), adrenal suppression (rs591118), and decreased bone mineral density (rs6461639) and accretion (rs9896933, rs2074439). Two of these polymorphisms were replicated within the paper, but none had external replication. Priorities from PiCA consortia members (representing 15 institution in eight countries) for future studies were tachycardia (SABA/LABA), adrenal suppression/crisis and growth suppression (corticosteroids), sleep/behaviour disturbances (leukotriene receptor antagonists), and nausea and vomiting (theophylline). Future pharmacogenomic studies in asthma should collect relevant ADR data as well as markers of efficacy.

Breath Biopsy Assessment of Liver Disease Using an Exogenous Volatile Organic Compound-Toward Improved Detection of Liver Impairment

INTRODUCTION

Liver cirrhosis and its complication - hepatocellular carcinoma (HCC) - have been associated with increased exhaled limonene. It is currently unclear whether this increase is more strongly associated with the presence of HCC or with the severity of liver dysfunction.

METHODS

We compared the exhaled breath of 40 controls, 32 cirrhotic patients, and 12 cirrhotic patients with HCC using the Breath Biopsy platform. Breath samples were analyzed by thermal desorption-gas chromatography-mass spectrometry. Limonene levels were compared between the groups and correlated to bilirubin, albumin, prothrombin time international normalized ratio, and alanine aminotransferase.

RESULTS

Breath limonene concentration was significantly elevated in subjects with cirrhosis-induced HCC (M: 82.1 ng/L, interquartile range [IQR]: 16.33-199.32 ng/L) and cirrhosis (M: 32.6 ng/L, IQR: 6.55-123.07 ng/L) compared with controls (M: 6.2 ng/L, IQR: 2.62-9.57 ng/L) (P value = 0.0005 and 0.0001, respectively) with no significant difference between 2 diseased groups (P value = 0.37). Levels of exhaled limonene correlated with serum bilirubin (R = 0.25, P value = 0.0016, r = 0.51), albumin (R = 0.58, P value = 5.3e-8, r = -0.76), and international normalized ratio (R = 0.29, P value = 0.0003, r = 0.51), but not with alanine aminotransferase (R = 0.01, P value = 0.36, r = 0.19).

DISCUSSION

Exhaled limonene levels are primarily affected by the presence of cirrhosis through reduced liver functional capacity, as indicated by limonene correlation with blood metrics of impaired hepatic clearance and protein synthesis capacity, without further alterations observed in subjects with HCC. This suggests that exhaled limonene is a potential non-invasive marker of liver metabolic capacity (see Visual abstract, Supplementary Digital Content 1, http://links.lww.com/CTG/A388).

Young children experience little emotional burden during invasive procedures in asthma research

Research in children should strike the right balance between protecting underage study subjects and advancing the medical field. This study gives insight into the emotional burden that common invasive research procedures in asthma research have on young children, both from the child and parent perspective. Puppetry was used to stimulate children (age 5-6 years) to explain their emotional burden prior to and after the research procedures. We operationalised emotional burden as willingness to participate in future research and reluctance towards participation. Parents filled out a questionnaire on this topic. Symptomatic patients as well as healthy controls were analysed. Forty-one children were included. Children's anticipatory fear for future research showed a clear decrease of 0.7 ± 1.6 on a 5-point Likert scale as a consequence of participation (p = 0.02). Sixty percent of all participating children explicitly indicated willingness to undergo identical research procedures again. Children uninformed by their parents about the venipuncture were significantly more reluctant to the venipuncture after the procedure (p < 0.01), compared to children who had been informed (4.0 ± 0.9 resp. 2.8 ± 1.2).Conclusion: This study suggests that the emotional burden of participation in asthma research for underage children can be prevented when they are properly informed and decreases as a consequence of participations. We believe increased emphasis should be placed on informing children and evaluating the emotional impact of research to help caretakers and research ethics committees make informed decisions about participation of children in medical research. What is Known: • Medical professionals and parents are likely to overestimate children's discomfort undergoing (invasive) research procedures. • Two thirds of children (age 6-18 years) participating in medical research indicated that they would participate in the same research study again. What is New: • Pre-school children experience little emotional burden during invasive procedures in asthma research. • Proper communication about (invasive) research procedures in pre-school children helps to reduce the anticipatory fear of these procedures in the future.

Breathomics from exhaled volatile organic compounds in pediatric asthma

Asthma is the most common chronic disease in children, and is characterized by airway inflammation, bronchial hyperresponsiveness, and airflow obstruction. Asthma diagnosis, phenotyping, and monitoring are still challenging with currently available methods, such as spirometry, F_E NO or sputum analysis. The analysis of volatile organic compounds (VOCs) in exhaled breath could be an interesting non-invasive approach, but has not yet reached clinical practice. This review describes the current status of breath analysis in the diagnosis and monitoring of pediatric asthma. Furthermore, features of an ideal breath test, different breath analysis techniques, and important methodological issues are discussed. Although only a (small) number of studies have been performed in pediatric asthma, of which the majority is focusing on asthma diagnosis, these studies show moderate to good prediction accuracy (80-100%, with models including 6-28 VOCs), thereby qualifying breathomics for future application. However, standardization of procedures, longitudinal studies, as well as external validation are needed in order to further develop breathomics into clinical tools. Such a non-invasive tool may be the next step toward stratified and personalized medicine in pediatric respiratory disease.

Rationale and design of the multiethnic Pharmacogenomics in Childhood Asthma consortium

AIM

International collaboration is needed to enable large-scale pharmacogenomics studies in childhood asthma. Here, we describe the design of the Pharmacogenomics in Childhood Asthma (PiCA) consortium.

MATERIALS & METHODS

Investigators of each study participating in PiCA provided data on the study characteristics by answering an online questionnaire.

RESULTS

A total of 21 studies, including 14,227 children/young persons (58% male), from 12 different countries are currently enrolled in the PiCA consortium. Fifty six percent of the patients are Caucasians. In total, 7619 were inhaled corticosteroid users. Among patients from 13 studies with available data on asthma exacerbations, a third reported exacerbations despite inhaled corticosteroid use. In the future pharmacogenomics studies within the consortium, the pharmacogenomics analyses will be performed separately in each center and the results will be meta-analyzed.

CONCLUSION

PiCA is a valuable platform to perform pharmacogenetics studies within a multiethnic pediatric asthma population.

A European Respiratory Society technical standard: exhaled biomarkers in lung disease

Breath tests cover the fraction of nitric oxide in expired gas (F_eNO), volatile organic compounds (VOCs), variables in exhaled breath condensate (EBC) and other measurements. For EBC and for F_eNO, official recommendations for standardised procedures are more than 10 years old and there is none for exhaled VOCs and particles. The aim of this document is to provide technical standards and recommendations for sample collection and analytic approaches and to highlight future research priorities in the field. For EBC and F_eNO, new developments and advances in technology have been evaluated in the current document. This report is not intended to provide clinical guidance on disease diagnosis and management.Clinicians and researchers with expertise in exhaled biomarkers were invited to participate. Published studies regarding methodology of breath tests were selected, discussed and evaluated in a consensus-based manner by the Task Force members.Recommendations for standardisation of sampling, analysing and reporting of data and suggestions for research to cover gaps in the evidence have been created and summarised.Application of breath biomarker measurement in a standardised manner will provide comparable results, thereby facilitating the potential use of these biomarkers in clinical practice.

Exhaled Molecular Fingerprinting in Diagnosis and Monitoring: Validating Volatile Promises

Medical diagnosis and phenotyping increasingly incorporate information from complex biological samples. This has promoted the development and clinical application of non-invasive metabolomics in exhaled air (breathomics). In respiratory medicine, expired volatile organic compounds (VOCs) are associated with inflammatory, oxidative, microbial, and neoplastic processes. After recent proof of concept studies demonstrating moderate to good diagnostic accuracies, the latest efforts in breathomics are focused on optimization of sensor technologies and analytical algorithms, as well as on independent validation of clinical classification and prediction. Current research strategies are revealing the underlying pathophysiological pathways as well as clinically-acceptable levels of diagnostic accuracy. Implementing recent guidelines on validating molecular signatures in medicine will enhance the clinical potential of breathomics and the development of point-of-care technologies.

Clinical, virological and epidemiological characteristics of rhinovirus infections in early childhood: A comparison between non-hospitalised and hospitalised children

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Rhinoviruses (RV) frequently cause respiratory tract infections in young children.

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We evaluated characteristics of RV infections in relation to clinical outcome.

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In young children clinical outcome was not related to RV species or types.

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Outcome of RV disease is more likely influenced by multiple (host-specific) factors.

Background

Several studies have been published regarding the epidemiology and clinical significance of the different rhinovirus (RV) species (-A, -B and -C). However, data on RV types and the associations with clinical outcome in young children are limited. Here, we investigated the clinical, virological and epidemiological characteristics of RV infections in young children with mild or asymptomatic infection (non-hospitalised children) and in symptomatic young children admitted to the hospital.

Objectives

The aim of this study was to evaluate associations between different characteristics of RV infections and clinical outcome in young children.

Study design

RV-infected children were retrospectively selected from a Dutch birth cohort (EUROPA-study) and from hospitalised children admitted to the hospital because of respiratory symptoms. In total 120 RV-typed samples could be selected from 65 non-hospitalised and 49 hospitalised children between November 2009 and December 2012.

Results

RV-A was the predominant species in both study populations, followed closely by RV-C. RV-B was observed only sporadically. The distribution of the RV species was comparable in non-hospitalised and hospitalised children. In children with respiratory distress who required ICU-admission the distribution of RV species did not differ significantly from the non-hospitalised children. No predominant RV type was present in non-hospitalised nor hospitalised children. However, hospitalised children were younger, had more often an underlying illness, a higher RV load and more frequently a bacterial co-infection.

Conclusions

Clinical outcome of RV infected young children was not related to RV species or types, but may more likely be influenced by multiple (host-specific) factors.

Flatography: Detection of gastrointestinal diseases by faecal gas analysis

Patients presenting with gastro-intestinal symptoms might suffer from a range of possible underlying diseases. An unmet need exists for novel cost-effective, reproducible, easy-to-perform and non-invasive tests. Hippocrates used body odours to diagnose diseases circa 460 before Christ. The art of diagnostic smelling is making a promising high-tech come-back with portable “electronic diagnostic noses”. Analysis of faecal volatile organic compounds is a novel field in metabolomics with considerable potential to improve the diagnosis, phenotyping and monitoring of gastro-intestinal disease. Challenges will be to mature over the coming years by development of a standardized methodology for stool sample collection, storage, handling and analysis. Furthermore, key volatiles need to be identified to improve test accuracy and sensitivity by development of sensors tailored toward the accurate identification of disease specific volatiles. If these challenges are adequately faced, analysis of faecal volatiles has realistic potential to considerably improve screening, diagnosis and disease monitoring for gastro-intestinal diseases.

Altered exhaled biomarker profiles in children during and after rhinovirus-induced wheeze

Preschool rhinovirus-induced wheeze is associated with an increased risk of asthma. In adult asthma, exhaled volatile organic compounds (VOC) are associated with inflammatory activity. We therefore hypothesised that acute preschool wheeze is accompanied by a differential profile of exhaled VOC, which is maintained after resolution of symptoms in those children with rhinovirus-induced wheeze. We included 178 children (mean±sd age 22±9 months) from the EUROPA cohort comparing asymptomatic and wheezing children during respiratory symptoms and after recovery. Naso- and oropharyngeal swabs were tested for rhinovirus by quantitative PCR. Breath was collected via a spacer and analysed using an electronic nose. Between-group discrimination was assessed by constructing a 1000-fold cross-validated receiver operating characteristic curve. Analyses were stratified by rhinovirus presence/absence. Wheezing children demonstrated a different VOC profile when compared with asymptomatic children (p<0.001), regardless of the presence (area under the curve (AUC) 0.77, 95% CI 0.07) or absence (AUC 0.81, 95% CI 0.05) of rhinovirus. After symptomatic recovery, discriminative accuracy was maintained in children with rhinovirus-induced wheeze (AUC 0.84, 95% CI 0.06), whereas it dropped significantly in infants with non-rhinovirus-induced wheeze (AUC 0.67, 95% CI 0.06). Exhaled molecular profiles differ between preschool children with and without acute respiratory wheeze. This appears to be sustained in children with rhinovirus-induced wheeze after resolution of symptoms. Therefore, exhaled VOC may qualify as candidate biomarkers for early signs of asthma.

Faecal gas analysis by electronic nose as novel, non-invasive method for assessment of active and quiescent paediatric inflammatory bowel disease: Proof of principle study

BACKGROUND AND AIMS

Inflammatory bowel disease (IBD) and its two phenotypes ulcerative colitis (UC) and Crohn's disease (CD) are essentially assessed by endoscopy, both in initial diagnostic work-up and during follow-up. This carries a high burden, especially on paediatric patients. Faecal volatile organic compounds (VOCs) are considered potential non-invasive biomarkers for intestinal diseases linked to gut microbiota alterations. We hypothesized that faecal VOC analysis by electronic nose allows discrimination of children with CD, UC and controls during active disease and remission.

METHODS

Faecal VOC patterns of children with newly diagnosed IBD and controls were studied by an electronic nose (Cyranose 320®), at baseline and upon achieving remission at 6-weeks of follow-up. Disease activity was assessed by global physician's assessment, substantiated by serum C-reactive protein and faecal calprotectin. Internally cross-validated receiver-operator-characteristic curves and corresponding sensitivity and specificity for detection of IBD were calculated RESULTS: Faecal VOC profiles of patients with UC (26) and CD (29) differed from controls (28); in active disease (AUC±95% CI, p-value, sensitivity, specificity: 1.00±0.00; p<0.001, 100%, 100%) and (0.85±0.05, p<0.001, 86%, 67%) and in clinical remission (0.94±0.06, p<0.001, 94%, 94%) and (0.94±0.06, p<0.001, 94%, 94%), respectively. Furthermore, CD-patients differed from UC-patients during active disease (0.96±0.03; p<0.001, 97%, 92%), and upon achieving clinical remission (0.81±0.08, p=0.002, 88%, 72%).

CONCLUSION

Faecal VOC analysis allowed discrimination of paediatric patients with IBD from controls, both during active disease and remission. It therefore has potential as non-invasive test, in both diagnostic work-up and assessment of disease activity in IBD.

The scent of colorectal cancer: detection by volatile organic compound analysis

The overall metabolic state of an individual is reflected by emitted volatile organic compounds (VOCs), which are gaseous carbon-based chemicals. In this review, we will describe the potential of VOCs as fully noninvasive markers for the detection of neoplastic lesions of the colon. VOCs are detected by our sensory olfactory nerves and form the molecular basis for our sense of smell. As such, we emit our own individual odor fingerprint or so-called smellprint. This may change over time in response to any alteration in metabolism such as modifications caused by gastrointestinal infection, inflammation, external factors such as medication and diet, or development of neoplastic disease such as colorectal cancer. This means that analysis of VOCs can provide a fully noninvasive metabolomics biomarker profile that could be used as a diagnostic tool. Thus far, canine scent detection, gas chromatography-mass spectrometry, and electronic nose technologies allow for discrimination between patients with and without colorectal cancer and also its precursor (advanced adenoma) with promising accuracy. The challenge for future research is to identify specific biomarkers driving these signals. This enables the development of primed sensors tailored toward accurate identification of volatiles specific to colorectal cancer and adenomas. Such a technique may allow noninvasive monitoring of response to therapy and could revolutionize screening practices for colorectal cancer and potentially many other gastrointestinal diseases.

Electronic nose breathprints are independent of acute changes in airway caliber in asthma

Molecular profiling of exhaled volatile organic compounds (VOC) by electronic nose technology provides breathprints that discriminate between patients with different inflammatory airway diseases, such as asthma and COPD. However, it is unknown whether this is determined by differences in airway caliber. We hypothesized that breathprints obtained by electronic nose are independent of acute changes in airway caliber in asthma. Ten patients with stable asthma underwent methacholine provocation (Visit 1) and sham challenge with isotonic saline (Visit 2). At Visit 1, exhaled air was repetitively collected pre-challenge, after reaching the provocative concentration (PC(20)) causing 20% fall in forced expiratory volume in 1 second (FEV(1)) and after subsequent salbutamol inhalation. At Visit 2, breath was collected pre-challenge, post-saline and post-salbutamol. At each occasion, an expiratory vital capacity was collected after 5 min of tidal breathing through an inspiratory VOC-filter in a Tedlar bag and sampled by electronic nose (Cyranose 320). Breathprints were analyzed with principal component analysis and individual factors were compared with mixed model analysis followed by pairwise comparisons. Inhalation of methacholine led to a 30.8 ± 3.3% fall in FEV(1) and was followed by a significant change in breathprint (p = 0.04). Saline inhalation did not induce a significant change in FEV(1), but altered the breathprint (p = 0.01). However, the breathprint obtained after the methacholine provocation was not significantly different from that after saline challenge (p = 0.27). The molecular profile of exhaled air in patients with asthma is altered by nebulized aerosols, but is not affected by acute changes in airway caliber. Our data demonstrate that breathprints by electronic nose are not confounded by the level of airway obstruction.

Exhaled breath profiling enables discrimination of chronic obstructive pulmonary disease and asthma

RATIONALE

Chronic obstructive pulmonary disease (COPD) and asthma can exhibit overlapping clinical features. Exhaled air contains volatile organic compounds (VOCs) that may qualify as noninvasive biomarkers. VOC profiles can be assessed using integrative analysis by electronic nose, resulting in exhaled molecular fingerprints (breathprints).

OBJECTIVES

We hypothesized that breathprints by electronic nose can discriminate patients with COPD and asthma.

METHODS

Ninety subjects participated in a cross-sectional study: 30 patients with COPD (age, 61.6 +/- 9.3 years; FEV(1), 1.72 +/- 0.69 L), 20 patients with asthma (age, 35.4 +/- 15.1 years; FEV(1) 3.32 +/- 0.86 L), 20 nonsmoking control subjects (age, 56.7 +/- 9.3 years; FEV(1), 3.44 +/- 0.76 L), and 20 smoking control subjects (age, 56.1 +/- 5.9 years; FEV(1), 3.58 +/- 0.78). After 5 minutes of tidal breathing through an inspiratory VOC filter, an expiratory vital capacity was collected in a Tedlar bag and sampled by electronic nose. Breathprints were analyzed by discriminant analysis on principal component reduction resulting in cross-validated accuracy values (accuracy). Repeatability and reproducibility were assessed by measuring samples in duplicate by two devices.

MEASUREMENTS AND MAIN RESULTS

Breathprints from patients with asthma were separated from patients with COPD (accuracy 96%; P < 0.001), from nonsmoking control subjects (accuracy, 95%; P < 0.001), and from smoking control subjects (accuracy, 92.5%; P < 0.001). Exhaled breath profiles of patients with COPD partially overlapped with those of asymptomatic smokers (accuracy, 66%; P = 0.006). Measurements were repeatable and reproducible.

CONCLUSIONS

Molecular profiling of exhaled air can distinguish patients with COPD and asthma and control subjects. Our data demonstrate a potential of electronic noses in the differential diagnosis of obstructive airway diseases and in the risk assessment in asymptomatic smokers. Clinical trial registered with www.trialregister.nl (NTR 1282).