Lung epithelium-specific proteins: characteristics and potential applications as markers

Occupational health of drilling waste workers as related to microbial exposure and waste treatment methods

OBJECTIVES

Exposure to microorganisms is a known contributor to occupational disease. This study assessed drilling waste workers' health status and investigated the potential of inhalable bioaerosols to elicit an immune response in vitro and in vivo.

METHODS

Venous blood and self-reported health data were collected from 56 and 73 Norwegian drilling waste workers, respectively. Immunological effects were assessed as Toll-like receptor (TLR) activation potential of personal air samples in vitro and biomarker expression in workers' plasma samples in vivo. Parameters, such as BMI, sex, and smoking habits, were considered along with factors such as purification technology of drilling waste when biomarker expression was interpreted. Symptom prevalence among exposed workers was compared to an unexposed control group.

RESULTS

Personal air samples activated TLR signalling in vitro in 90% of all cases. The activation potential correlated significantly with work exposure to microbial agents and total dust. Significant differences in biomarker expression and symptom prevalence were identified between purification technologies and exposure groups. Drilling waste workers had significantly increased OR of skin irritation and respiratory symptoms compared to the control group.

CONCLUSIONS

Exposure to microorganisms during the treatment of offshore drilling waste is an occupational health concern.

Investigation of surfactant apoproteins and Brucella sp. antigens in the lungs of aborted bovine fetuses and neonatal calves delivered weak

The main objectives of this study were to investigate surfactant apoprotein expression (SP) and to detect Brucella sp. antigens in the lungs of aborted bovine fetuses and neonatal calves delivered weak. The Avidin-Biotin-Peroxidase Complex (ABC) and the indirect immunofluorescence (IF) techniques were applied, using antibodies to the lung surfactant apoproteins (SP-A, SP-B, SP-C) and Brucella sp. antigens. Hyperplasia of type II cells was also assessed by evaluating Thyroid Transcription Factor-1 (TTF-1), Proliferating Cell Nuclear Antigen (PCNA), and Cytokeratin Pan Type I/II (CK-P) markers. The study materials were the lungs of 46 aborted bovine fetuses and 20 neonatal calves delivered weak. Brucella sp.-positive fetal lungs displayed bronchopneumonia in 24 cases. The lungs of the weak-delivered neonates which were positive for Brucella sp. also showed pneumonia. Bacterial culture detected positivity in 11 of 46 fetuses and two neonates. IHC for Brucella sp. antigens found positivity in 22 of 46 fetuses and four neonates. Thus, our research revealed that the IHC technique using anti-Brucella sp. antibodies was useful for detecting Brucella sp. in autolytic and culture-negative fetuses. The study also found that surfactant synthesis begins close to the 7th month of gestation in bovine fetuses. Immunolabeling to SPs occurred in the cytoplasm of both type II and Clara cells, along with SP-C only in type II pneumocytes. The IF yielded dense labeling for Brucella sp. antigens, SP-B, and CK-P, respectively, in the phagocytic cells and epithelium of the airways. Also, pneumonia in newborn calves indicates an intrauterine infection by Brucella sp.

Poor prognostic factors for relapse of interstitial lung disease with anti-aminoacyl-tRNA synthetase antibodies after combination therapy

Introduction

This study aimed to identify useful clinical indicators for predicting the relapse of interstitial lung disease (ILD) complicated with anti-aminoacyl-tRNA synthetase (ARS) antibodies (anti-ARS-ILD), being treated with prednisolone and calcineurin inhibitors.

Methods

Fifty patients with anti-ARS-ILD were enrolled between October 2014 and August 2022. All patients were treated with prednisolone and calcineurin inhibitors as remission induction therapy and followed up for over a year with these combination therapies. We examined patients who experienced ILD relapse after immunosuppressive treatment. We explored the risk factors for predicting ILD relapse in these patients by comparing demographic, clinical, laboratory, and radiological findings and treatments between the relapsed and non-relapsed groups on admission.

Results

Of the 50 patients, 19 (38%) relapsed during a median follow-up of 4.8 years. Univariate and multivariate Cox regression analyses identified the presence of acute/subacute (A/S)-ILD, higher serum aldolase (ALD) and surfactant protein-D (SP-D) levels, and lower %forced vital capacity (FVC) as risk factors for relapse in patients with anti-ARS-ILD. Using the receiver operating curve analysis, ALD ≥6.3 U/L, SP-D ≥207 ng/mL, and %FVC ≤76.8% were determined as the cut-off levels for indicating a poor prognosis. The 5-year relapse rate was significantly higher in patients with A/S-ILD, serum ALD≥6.3 U/L, serum SP-D ≥207 ng/mL, or %FVC of ≤76.8% than in those without these parameters. (P=0.009, 0.0005, 0.0007, 0.0004, respectively) Serum ALD levels were significantly correlated with the disease activity indicators of anti-ARS-ILD.

Conclusion

The presence of A/S-ILD, higher serum ALD and SP-D levels, and lower %FVC are useful indicators for predicting anti-ARS-ILD relapse.

Forensic application of three interstitial pneumonia markers: search for new pneumonia markers in dead bodies

In forensic cases, detailed identification of pneumonia is important. Our objective was to statistically determine the applicability of three interstitial lung disease (ILD) markers for forensic diagnosis using serum collected from dead bodies with various postmortem intervals (PMIs). We retrospectively analyzed the levels of postmortem serum Krebs von den Lungen-6 (KL-6) and pulmonary surfactant-associated proteins A and D (SP-A and SP-D) using 221 samples obtained during forensic autopsy at our facility from 2019 to 2023. We evaluated the diagnostic efficacy of ILD markers for various pneumonias against the pathological diagnosis, and examined the assessment of the severity of ILD. When comparing the ILD group with bacterial pneumonia (BP) versus the control group, there was a significant increase in KL-6 in the ILD group. When comparing the severe ILD (SILD) group with the mild ILD (MILD) group, there was a significant increase in KL-6 and SP-D in the SILD group. The optimal cutoff values for differentiating SILD were 607.0 U/mL for KL-6, 55.5 ng/mL for SP-A, and 160.0 ng/mL for SP-D, and the sensitivity/specificity (%) of KL-6, SP-A, and SP-D for SILD were 84.1/95.2, 55.6/85.7, and 66.7/74.6, respectively. This is the first study to examine KL-6 in postmortem serum in forensic medicine. By analyzing dead bodies with various PMIs, our results confirmed statistically that postmortem serum KL-6 specifically detects ILD, postmortem serum SP-A has high sensitivity to lung injury, and postmortem serum SP-D is potentially useful in assessing the severity of ILD.

Lung Organoids: Systematic Review of Recent Advancements and its Future Perspectives

Organoids are essentially an in vitro (lab-grown) three-dimensional tissue culture system model that meticulously replicates the structure and physiology of human organs. A few of the present applications of organoids are in the basic biological research area, molecular medicine and pharmaceutical drug testing. Organoids are crucial in connecting the gap between animal models and human clinical trials during the drug discovery process, which significantly lowers the time duration and cost associated with each stage of testing. Likewise, they can be used to understand cell-to-cell interactions, a crucial aspect of tissue biology and regeneration, and to model disease pathogenesis at various stages of the disease. Lung organoids can be utilized to explore numerous pathophysiological activities of a lung since they share similarities with its function. Researchers have been trying to recreate the complex nature of the lung by developing various "Lung organoids" models.This article is a systematic review of various developments of lung organoids and their potential progenitors. It also covers the in-depth applications of lung organoids for the advancement of translational research. The review discusses the methodologies to establish different types of lung organoids for studying the regenerative capability of the respiratory system and comprehending various respiratory diseases.Respiratory diseases are among the most common worldwide, and the growing burden must be addressed instantaneously. Lung organoids along with diverse bio-engineering tools and technologies will serve as a novel model for studying the pathophysiology of various respiratory diseases and for drug screening purposes.

Evaluating the diagnostic and therapeutic significance of KL-6 in patients with interstitial lung diseases

Background

This study aimed to assess the diagnostic value of Krebs von den Lungen-6 (KL-6), Surfactant protein-A (SP-A), SP-D and molecular matrixmetalloproteinase-7 (MMP-7) in discriminating patients with interstitial lung diseases (ILDs) from disease control subjects.

Methods

Serum levels of KL-6, SP-A, SP-D and MMP-7 were measured in both the ILD and non-ILD (NILD) groups. Receiver operating characteristic (ROC) curve analysis was conducted to evaluate the diagnostic potential of these markers and laboratory indices. High-resolution computed tomography (HRCT) fibrosis scores were determined, and their correlation with the serum markers was analyzed.

Results

Serum levels of KL-6 and MMP-7 were significantly elevated in the ILD group compared to the control group, while no significant differences were observed for SP-A and SP-D. ROC analysis of KL-6 demonstrated superior diagnostic accuracy, with a sensitivity of 76.36%, specificity of 91.07%, and an area under curve (AUC) of 0.902 (95%CI 0.866-0.945). These findings were consistent across an additional cohort. Correlation analysis revealed a link between KL-6 levels at initial diagnosis and HRCT fibrosis scores, indicating disease severity. Moreover, a negative correlation was found between KL-6 and pulmonary function indices, reflecting disease progression. Patients with increased 12-month HRCT fibrosis score showed higher lactate dehydrogenase (LDH) levels, with LDH exhibiting an AUC of 0.767 (95% CI: 0.520-0.927) as a predictor of progression.

Conclusions

Serum KL-6 detection proves to be a valuable tool for accurately distinguishing ILDs from control subjects. While KL-6 shows a correlation with HRCT fibrosis scores and a negative association with pulmonary function indices, its predictive value for ILDs prognosis is limited.

Trial registration

This study received retrospective approval from the Ethical Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (institutional review board ID: TJ-IRB20210331, date: 2021.03.30).

Club Cells-A Guardian against Occupational Hazards

Club cells have a distinct role in the epithelial repair and defense mechanisms of the lung. After exposure to environmental pollutants, during chronic exposure, the secretion of club cells secretory protein (CCSP) decreases. Exposure to occupational hazards certainly has a role in a large number of interstitial lung diseases. According to the American Thoracic Society and the European Respiratory Society, around 40% of the all interstitial lung disease is attributed to occupational hazards. Some of them are very well characterized (pneumoconiosis, hypersensitivity pneumonitis), whereas others are consequences of acute exposure (e.g., paraquat) or persistent exposure (e.g., isocyanate). The category of vapors, gases, dusts, and fumes (VGDF) has been proven to produce subclinical modifications. The inflammation and altered repair process resulting from the exposure to occupational respiratory hazards create vicious loops of cooperation between epithelial cells, mesenchymal cells, innate defense mechanisms, and immune cells. The secretions of club cells modulate the communication between macrophages, epithelial cells, and fibroblasts mitigating the inflammation and/or reducing the fibrotic process. In this review, we describe the mechanisms by which club cells contribute to the development of interstitial lung diseases and the potential role for club cells as biomarkers for occupational-related fibrosis.

Association of Serum Krebs von den Lungen-6 (KL-6) Levels and Disease Severity in Patients Hospitalized with COVID-19

Objective

We aimed to evaluate Krebs von den Lungen-6 (KL-6) as a possible biomarker in determining disease severity in patients with moderate and severe COVID-19.

Materials and Methods

This cross-sectional study included moderate or severe COVID-19 patients; critically ill patients who were followed up in the intensive care unit were not included. KL-6 level and routine laboratory test measurements were performed on the first day of admission. The patients were also categorized according to their hyperinflammatory state.

Results

The study included 92 patients, 56 (61%) women. The National Institutes of Health (NIH) score was 2 in 52.2% of the patients and 3 in 47.8%. KL-6 levels did not significantly differ in disease severity (NIH score 2 vs. 3; p=0.15). Median KL-6 values were 52.7 (29.1) in patients with <2 COVID-19 hyperinflammatory syndrome score (cHIS) and 61.7 (32.2) in patients with cHIS ≥ 2 (p= 0.077). KL-6 values tended to be higher among the patients with lower lymphocyte counts, but the difference was not statistically significant (<1000 mm³/L p=0.006 and higher cHIS scores ≥2 p=0.07). KL-6 values were also higher in the patients with diabetes mellitus compared to the remaining patients (p =0.036).

Conclusion

There was no significant association between the serum KL-6 measured at admission and the severity of COVID-19.

Free and Interfacial Boundaries in Individual-Based Models of Multicellular Biological systems

Coordination of cell behaviour is key to a myriad of biological processes including tissue morphogenesis, wound healing, and tumour growth. As such, individual-based computational models, which explicitly describe inter-cellular interactions, are commonly used to model collective cell dynamics. However, when using individual-based models, it is unclear how descriptions of cell boundaries affect overall population dynamics. In order to investigate this we define three cell boundary descriptions of varying complexities for each of three widely used off-lattice individual-based models: overlapping spheres, Voronoi tessellation, and vertex models. We apply our models to multiple biological scenarios to investigate how cell boundary description can influence tissue-scale behaviour. We find that the Voronoi tessellation model is most sensitive to changes in the cell boundary description with basic models being inappropriate in many cases. The timescale of tissue evolution when using an overlapping spheres model is coupled to the boundary description. The vertex model is demonstrated to be the most stable to changes in boundary description, though still exhibits timescale sensitivity. When using individual-based computational models one should carefully consider how cell boundaries are defined. To inform future work, we provide an exploration of common individual-based models and cell boundary descriptions in frequently studied biological scenarios and discuss their benefits and disadvantages.

Detection of abused drugs in human exhaled breath using mass spectrometry: A review

RATIONALE

Human breath analysis has been attracting increasing interest in the detection of abused drugs in forensic and clinical applications because of its noninvasive sampling and distinctive molecular information. Mass spectrometry (MS)-based approaches have been proven to be powerful tools for accurately analyzing exhaled abused drugs. The major advantages of MS-based approaches include high sensitivity, high specificity, and versatile couplings with various breath sampling methods.

METHODS

Recent advances in the methodological development of MS analysis of exhaled abused drugs are discussed. Breath collection and sample pretreatment methods for MS analysis are also introduced.

RESULTS

Recent advances in technical aspects of breath sampling methods are summarized, highlighting active and passive sampling. MS methods for detecting different exhaled abused drugs are reviewed, emphasizing their features, advantages, and limitations. The future trends and challenges in MS-based breath analysis of exhaled abused drugs are also discussed.

CONCLUSIONS

The coupling of breath sampling methods with MS approaches has been proven to be a powerful tool for the detection of exhaled abused drugs, offering highly attractive results in forensic investigations. MS-based detection of exhaled abused drugs in exhaled breath is a relatively new field and is still in the early stages of methodological development. New MS technologies promise a substantial benefit for future forensic analysis.

Extracellular Acetylated Histone 3.3 Induces Inflammation and Lung Tissue Damage

Extracellular histones, part of the protein group known as damage-associated molecular patterns (DAMPs), are released from damaged or dying cells and can instigate cellular toxicity. Within the context of chronic obstructive pulmonary disease (COPD), there is an observed abundance of extracellular histone H3.3, indicating potential pathogenic implications. Notably, histone H3.3 is often found hyperacetylated (AcH3.3) in the lungs of COPD patients. Despite these observations, the specific role of these acetylated histones in inducing pulmonary tissue damage in COPD remains unclear. To investigate AcH3.3's impact on lung tissue, we administered recombinant histones (rH2A, rH3.3, and rAcH3.3) or vehicle solution to mice via intratracheal instillation. After 48 h, we evaluated the lung toxicity damage and found that the rAcH3.3 treated animals exhibited more severe lung tissue damage compared to those treated with non-acetylated H3.3 and controls. The rAcH3.3 instillation resulted in significant histological changes, including alveolar wall rupture, epithelial cell damage, and immune cell infiltration. Micro-CT analysis confirmed macroscopic structural changes. The rAcH3.3 instillation also increased apoptotic activity (cleavage of caspase 3 and 9) and triggered acute systemic inflammatory marker activation (TNF-α, IL-6, MCP-3, or CXCL-1) in plasma, accompanied by leukocytosis and lymphocytosis. Confocal imaging analysis confirmed lymphocytic and monocytic/macrophage lung infiltration in response to H3.3 and AcH3.3 administration. Taken together, our findings implicate extracellular AcH3.3 in inducing cytotoxicity and acute inflammatory responses, suggesting its potential role in promoting COPD-related lung damage progression.

Extracellular vesicle-encapsulated CC16 as novel nanotherapeutics for treatment of acute lung injury

Acute lung injury (ALI) is still associated with high mortality. Growing evidence suggests that Club Cell Protein 16 (CC16) plays a protective role against ALI. However, the doses of recombinant CC16 (rCC16) used in preclinical studies are supraphysiological for clinical applications. Extracellular vesicles (EVs) are nanovesicles endogenously generated by mammalian cells. Our study demonstrated that CC16 is released via small EVs and EV-encapsulated CC16 (sEV-CC16) and has anti-inflammatory activities, which protect mice from lipopolysaccharide (LPS) or bacteria-induced ALI. Additionally, sEV-CC16 can activate the DNA damage repair signaling pathways. Consistent with this activity, we observed more severe DNA damage in lungs from Cc16 knockout (KO) than wild-type (WT) mice. Mechanistically, we elucidated that CC16 suppresses nuclear factor κB (NF-κB) signaling activation by binding to heat shock protein 60 (HSP60). We concluded that sEV-CC16 could be a potential therapeutic agent for ALI by inhibiting the inflammatory and DNA damage responses by reducing NF-κB signaling.

Diagnosis of Fibrotic Hypersensitivity Pneumonitis: Is There a Role for Biomarkers?

Hypersensitivity pneumonitis is a complex interstitial lung syndrome and is associated with significant morbimortality, particularly for fibrotic disease. This condition is characterized by sensitization to a specific antigen, whose early identification is associated with improved outcomes. Biomarkers measure objectively biologic processes and may support clinical decisions. These tools evolved to play a crucial role in the diagnosis and management of a wide range of human diseases. This is not the case, however, with hypersensitivity pneumonitis, where there is still great room for research in the path to find consensual diagnostic biomarkers. Gaps in the current evidence include lack of validation, validation against healthy controls alone, small sampling and heterogeneity in diagnostic and classification criteria. Furthermore, discriminatory accuracy is currently limited by overlapping mechanisms of inflammation, damage and fibrogenesis between ILDs. Still, biomarkers such as BAL lymphocyte counts and specific serum IgGs made their way into clinical guidelines, while others including KL-6, SP-D, YKL-40 and apolipoproteins have shown promising results in leading centers and have potential to translate into daily practice. As research proceeds, it is expected that the emergence of novel categories of biomarkers will offer new and thriving tools that could complement those currently available.

Low CC16 mRNA Expression Levels in Bronchial Epithelial Cells Are Associated with Asthma Severity

Rationale: CC16 is a protein mainly produced by nonciliated bronchial epithelial cells (BECs) that participates in host defense. Reduced CC16 protein concentrations in BAL and serum are associated with asthma susceptibility. Objectives: Few studies have investigated the relationship between CC16 and asthma progression, and none has focused on BECs. In this study, we sought to determine if CC16 mRNA expression levels in BECs are associated with asthma severity. Methods: Association analyses between CC16 mRNA expression levels in BECs (242 asthmatics and 69 control subjects) and asthma-related phenotypes in Severe Asthma Research Program were performed using a generalized linear model. Measurements and Main Results: Low CC16 mRNA expression levels in BECs were significantly associated with asthma susceptibility and asthma severity, high systemic corticosteroids use, high retrospective and prospective asthma exacerbations, and low pulmonary function. Low CC16 mRNA expression levels were significantly associated with high T2 inflammation biomarkers (fractional exhaled nitric oxide and sputum eosinophils). CC16 mRNA expression levels were negatively correlated with expression levels of Th2 genes (IL1RL1, POSTN, SERPINB2, CLCA1, NOS2, and MUC5AC) and positively correlated with expression levels of Th1 and inflammation genes (IL12A and MUC5B). A combination of two nontraditional T2 biomarkers (CC16 and IL-6) revealed four asthma endotypes with different characteristics of T2 inflammation, obesity, and asthma severity. Conclusions: Our findings indicate that low CC16 mRNA expression levels in BECs are associated with asthma susceptibility, severity, and exacerbations, partially through immunomodulation of T2 inflammation. CC16 is a potential nontraditional T2 biomarker for asthma development and progression.

Clinical Utility of Circulating Pneumoproteins as Diagnostic and Prognostic Biomarkers in COVID-19: A Systematic Review and Meta-analysis

INTRODUCTION

This study explored circulating pneumoproteins in the diagnosis, severity, and prognosis of COVID-19 by meta-analysis.

METHODS

We searched five databases and other sources until December 16, 2021. Standardized mean difference (SMD) and 95% confidence interval (CI) were the overall outcomes. RevMan 5.3, Stata 16, and Meta-DiSc 1.4 were utilized for pooled analysis.

RESULTS

A total of 2432 subjects from 26 studies were included. Patients with COVID-19 had higher circulating KL-6, SP-D, and SP-A levels (SMD 1.34, 95% CI [0.60, 2.08]; SMD 1.74, 95% CI [0.64, 2.84]; SMD 3.42, 95% CI [1.31, 5.53], respectively) than healthy individuals. Circulating SP-D levels were not significantly different in survivors and non-survivors (SMD - 0.19, 95% CI [- 0.78, 0.40]). Circulating KL-6, SP-D, and RAGE levels in patients with mild to moderate COVID-19 were significantly lower (SMD - 0.93, 95% CI [- 1.22, - 0.65]; SMD - 1.32, 95% CI [- 2.34, - 0.29]; SMD - 1.17, 95% CI [- 2.06, - 0.28], respectively) than in patients with severe COVID-19. Subgroup analysis suggested that country and total number may be related to the heterogeneity when analyzing SP-D in patients with mild to moderate vs. severe COVID-19. The meta-analysis of diagnostic accuracy including KL-6 for severity, KL-6 for mortality, and SP-D for severity demonstrated that they all had limited diagnostic value.

CONCLUSION

Therefore, circulating pneumoproteins (KL-6, SP-D, and RAGEs) reflect the diagnosis, severity, and prognosis of COVID-19, and follow-up studies are still needed.

Cold air exposure at - 15 °C induces more airway symptoms and epithelial stress during heavy exercise than rest without aggravated airway constriction

Purpose

Exposure to cold air may harm the airways. It is unclear to what extent heavy exercise adds to the cold-induced effects on peripheral airways, airway epithelium, and systemic immunity among healthy individuals. We investigated acute effects of heavy exercise in sub-zero temperatures on the healthy airways.

Methods

Twenty-nine healthy individuals underwent whole body exposures to cold air in an environmental chamber at − 15 °C for 50 min on two occasions; a 35-min exercise protocol consisting of a 5-min warm-up followed by 2 × 15 min of running at 85% of VO₂max vs. 50 min at rest. Lung function was measured by impulse oscillometry (IOS) and spirometry before and immediately after exposures. CC16 in plasma and urine, and cytokines in plasma were measured before and 60 min after exposures. Symptoms were surveyed pre-, during and post-trials.

Results

FEV₁ decreased after rest (− 0.10 ± 0.03 L, p < 0.001) and after exercise (− 0.06 ± 0.02 L, p = 0.012), with no difference between trials. Exercise in − 15 °C induced greater increases in lung reactance (X5; p = 0.023), plasma CC16 (p < 0.001) as well as plasma IL-8 (p < 0.001), compared to rest. Exercise induced more intense symptoms from the lower airways, whereas rest gave rise to more general symptoms.

Conclusion

Heavy exercise during cold air exposure at − 15 °C induced signs of an airway constriction to a similar extent as rest in the same environment. However, biochemical signs of airway epithelial stress, cytokine responses, and symptoms from the lower airways were more pronounced after the exercise trial.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00421-022-05004-3.

Urinary CC16, a potential indicator of lung integrity and inflammation, increases in children after short-term exposure to PM2.5/PM10 and is driven by the CC16 38GG genotype

Particular matter (PM) exposure is a big hazard for public health, especially for children. Serum CC16 is a well-known biomarker of respiratory health. Urinary CC16 (U-CC16) can be a noninvasive alternative, albeit requiring adequate adjustment for renal handling. Moreover, the SNP CC16 G38A influences CC16 levels. This study aimed to monitor the effect of short-term PM exposure on CC16 levels, measured noninvasively in schoolchildren, using an integrative approach. We used a selection of urine and buccal DNA samples from 86 children stored in an existing biobank. Using a multiple reaction monitoring method, we measured U-CC16, as well as RBP4 (retinol binding protein 4) and β2M (beta-2-microglobulin), required for adjustment. Buccal DNA samples were used for CC16 G38A genotyping. Linear mixed-effects models were used to find relevant associations between U-CC16 and previously obtained data from recent daily PM ≤ 2.5 or 10 μm exposure (PM_2.5, PM₁₀) modeled at the child's residence. Our study showed that exposure to low PM at the child's residence (median levels 18.9 μg/m³ (PM_2.5) and 23.6 μg/m³ (PM₁₀)) one day before sampling had an effect on the covariates-adjusted U-CC16 levels. This effect was dependent on the CC16 G38A genotype, due to its strong interaction with the association between PM levels and covariates-adjusted U-CC16 (P = 0.024 (PM_2.5); P = 0.061 (PM₁₀)). Only children carrying the 38GG genotype showed an increase of covariates-adjusted U-CC16, measured 24h after exposure, with increasing PM_2.5 and PM₁₀ (β = 0.332; 95% CI: 0.110 to 0.554 and β = 0.372; 95% CI: 0.101 to 0.643, respectively). To the best of our knowledge, this is the first study using an integrative approach to investigate short-term PM exposure of children, using urine to detect early signs of pulmonary damage, and taking into account important determinants such as the genetic background and adequate adjustment of the measured biomarker in urine.

Modelling realistic 3D deformations of simple epithelia in dynamic homeostasis

The maintenance of tissue and organ structures during dynamic homeostasis is often not well understood. In order for a system to be stable, cell renewal, cell migration and cell death must be finely balanced. Moreover, a tissue's shape must remain relatively unchanged. Simple epithelial tissues occur in various structures throughout the body, such as the endothelium, mesothelium, linings of the lungs, saliva and thyroid glands, and gastrointestinal tract. Despite the prevalence of simple epithelial tissues, there are few models which accurately describe how these tissues maintain a stable structure. Here, we present a novel, 3D, deformable, multilayer, cell-centre model of a simple epithelium. Cell movement is governed by the minimisation of a bending potential across the epithelium, cell-cell adhesion, and viscous effects. We show that the model is capable of maintaining a consistent tissue structure while undergoing self renewal. We also demonstrate the model's robustness under tissue renewal, cell migration and cell removal. The model presented here is a valuable advancement towards the modelling of tissues and organs with complex and generalised structures.

N-Acetylcysteine and Other Sulfur-Donors as a Preventative and Adjunct Therapy for COVID-19

The airway epithelial glycocalyx plays an important role in preventing severe acute respiratory syndrome coronavirus 2 entry into the epithelial cells, while the endothelial glycocalyx contributes to vascular permeability and tone, as well as modulating immune, inflammatory, and coagulation responses. With ample evidence in the scientific literature that coronavirus disease 2019 (COVID-19) is related to epithelial and endothelial dysfunction, preserving the glycocalyx should be the main focus of any COVID-19 treatment protocol. The most studied functional unit of the glycocalyx is the glycosaminoglycan heparan sulfate, where the degree and position of the sulfate groups determine the biological activity. N-acetylcysteine (NAC) and other sulfur donors contribute to the inorganic sulfate pool, the rate-limiting molecule in sulfation. NAC is not only a precursor to glutathione but also converts to hydrogen sulfide, inorganic sulfate, taurine, Coenzyme A, and albumin. By optimising inorganic sulfate availability, and therefore sulfation, it is proposed that COVID-19 can be prevented or at least most of the symptoms attenuated. A comprehensive COVID-19 treatment protocol is needed to preserve the glycocalyx in both the prevention and treatment of COVID-19. The use of NAC at a dosage of 600 mg bid for the prevention of COVID-19 is proposed, but a higher dosage of NAC (1200 mg bid) should be administered upon the first onset of symptoms. In the severe to critically ill, it is advised that IV NAC should be administered immediately upon hospital admission, and in the late stage of the disease, IV sodium thiosulfate should be considered. Doxycycline as a protease inhibitor will prevent shedding and further degradation of the glycocalyx.

Assessment of the Feasibility of a Future Integrated Larger-Scale Epidemiological Study to Evaluate Health Risks of Air Pollution Episodes in Children

Air pollution exposure can lead to exacerbation of respiratory disorders in children. Using sensitive biomarkers helps to assess the impact of air pollution on children’s respiratory health and combining protein, genetic and epigenetic biomarkers gives insights on their interrelatedness. Most studies do not contain such an integrated approach and investigate these biomarkers individually in blood, although its collection in children is challenging. Our study aimed at assessing the feasibility of conducting future integrated larger-scale studies evaluating respiratory health risks of air pollution episodes in children, based on a qualitative analysis of the technical and logistic aspects of a small-scale field study involving 42 children. This included the preparation, collection and storage of non-invasive samples (urine, saliva), the measurement of general and respiratory health parameters and the measurement of specific biomarkers (genetic, protein, epigenetic) of respiratory health and air pollution exposure. Bottlenecks were identified and modifications were proposed to expand this integrated study to a higher number of children, time points and locations. This would allow for non-invasive assessment of the impact of air pollution exposure on the respiratory health of children in future larger-scale studies, which is critical for the development of policies or measures at the population level.

Surfactant protein A in particles in exhaled air and plasma

Respiratory tract lining fluid (RTLF) is an important component of the lung epithelial barrier. Pathological changes in RTLF may cause increased permeability of the epithelial barrier, but changes within RTLF are difficult to assess non-invasively. The aim of this study was to explore if the use of the non-invasive measurement technique, Particles in Exhaled Air (PEx) and blood test were useful in assessing epithelial barrier, and if cigarette smoking affects the relationship. In a general population subcohort from the European Community Respiratory Health Survey III in Iceland (n = 112), we collected RTLF droplets using the PEx technique, in conjunction with blood samples and questionnaire data. We measured surfactant protein A (SP-A) in the collected plasma and PEx samples. Participants were defined as healthy if they did not currently have asthma, were non-smokers and had forced expiratory volume in one second ≥ 80% of predicted value. Of the 112 participants, 97 were healthy and 15 were current smokers. There was no correlation between plasma and PEx SP-A levels. However, the ratio of plasma to PEx SP-A was significantly higher in smokers compared to healthy subjects. The lack of correlation between PEx and plasma SP-A in healthy participants, indicates that SP-A in plasma does not diffuse freely over the lung epithelial barrier. However, the lung epithelial barrier may be injured by smoking, leading to diffusion of SP-A across the barrier into the bloodstream, causing an increased ratio of plasma to PEx SP-A.

Understanding the Pathobiology of Pulmonary Hypertension Due to Left Heart Disease

The development of pulmonary hypertension (PH) is common and has adverse prognostic implications in patients with heart failure due to left heart disease (LHD), and thus far, there are no known treatments specifically for PH-LHD, also known as group 2 PH. Diagnostic thresholds for PH-LHD, and clinical classification of PH-LHD phenotypes, continue to evolve and, therefore, present a challenge for basic and translational scientists actively investigating PH-LHD in the preclinical setting. Furthermore, the pathobiology of PH-LHD is not well understood, although pulmonary vascular remodeling is thought to result from (1) increased wall stress due to increased left atrial pressures; (2) hemodynamic congestion-induced decreased shear stress in the pulmonary vascular bed; (3) comorbidity-induced endothelial dysfunction with direct injury to the pulmonary microvasculature; and (4) superimposed pulmonary arterial hypertension risk factors. To ultimately be able to modify disease, either by prevention or treatment, a better understanding of the various drivers of PH-LHD, including endothelial dysfunction, abnormalities in vascular tone, platelet aggregation, inflammation, adipocytokines, and systemic complications (including splanchnic congestion and lymphatic dysfunction) must be further investigated. Here, we review the diagnostic criteria and various hemodynamic phenotypes of PH-LHD, the potential biological mechanisms underlying this disorder, and pressing questions yet to be answered about the pathobiology of PH-LHD.

A breathing mask attenuates acute airway responses to exercise in sub-zero environment in healthy subjects

PURPOSE

Cold air exposure is associated with increased respiratory morbidity and mortality. Repeated inhalation of cold and dry air is considered the cause of the high prevalence of asthma among winter endurance athletes. This study assessed whether a heat- and moisture-exchanging breathing device (HME) attenuates airway responses to high-intensity exercise in sub-zero temperatures among healthy subjects.

METHODS

Using a randomized cross-over design, 23 healthy trained participants performed a 30-min warm-up followed by a 4-min maximal, self-paced running time trial in - 15 °C, with and without HME. Lung function was assessed pre- and immediately post-trials. Club cell protein (CC-16), 8-isoprostane, and cytokine concentrations were measured in plasma and urine pre- and 60 min post trials. Symptoms were assessed prior to, during, and immediately after each trial in the chamber.

RESULTS

HME use attenuated the decrease in forced expiratory volume in 1 s (FEV₁) post trials (∆FEV₁: mean (SD) HME - 0.5 (1.9) % vs. no-HME - 2.7 (2.7) %, p = 0.002). HME also substantially attenuated the median relative increase in plasma-CC16 concentrations (with HME + 27% (interquartile range 9-38) vs no-HME + 121% (55-162), p < 0.001) and reduced airway and general symptom intensity, compared to the trial without HME. No significant changes between trials were detected in urine CC16, 8-isoprostane, or cytokine concentrations.

CONCLUSION

The HME attenuated acute airway responses induced by moderate-to-maximal-intensity exercise in - 15 °C in healthy subjects. Further studies are needed to examine whether this HMEs could constitute primary prevention against asthma in winter endurance athletes.

A Biomonitoring Pilot Study in Workers from a Paints Production Plant Exposed to Pigment-Grade Titanium Dioxide (TiO2)

Among particulate matter composing paints, titanium dioxide (TiO2) forms about 20% of the final suspension. Although TiO2 is broadly used in many applications, TiO2 powders represent an established respiratory hazard for workers with long-term exposure. In 35 workers of a paints production plant (15 exposed and 20 not exposed), we assessed pro-inflammatory cytokines (IL-1β, TNF-α, IL-10, IL-17), surfactant protein D (SP-D) and Krebs von den Lungen-6 glycoprotein (KL-6) in exhaled breath condensate (EBC). In urine samples, we measured 8-isoprostane (Isop) and Malondialdehyde (MDA) as biomarkers of oxidative stress, and Titanium (Ti-U) as a biomarker of exposure. Health status, habits and occupational history were recorded. Airborne respirable dusts and Ti were quantified. Particle number concentration and average diameter (nm) were detected by a NanoTracer™ monitoring device. Ti was measurable in filters collected at the respiratory breathing zone (0.11−0.44 µg/m3 8-h TWA). IL-1β and IL-10 values were significantly higher in exposed workers, whereas SP-D was significantly lower (p < 0.001). KL-6 was significantly higher in workers than in controls (p < 0.01). MDA levels were significantly increased in exposed workers and were positively correlated with Ti-U. Exposure to TiO2 in paint production is associated with the subtle alterations of lung pathobiology. These findings suggest the need for an integrated approach relying on both personal exposure and biomarker assessment to improve the hazard characterisation in occupational settings.

Circulating protein carbonyls are specifically elevated in critically ill patients with pneumonia relative to other sources of sepsis

BACKGROUND

Septic shock is a life-threatening dysregulated response to severe infection and is associated with elevated oxidative stress. We aimed to assess protein carbonyls in critically ill patients with different sources of sepsis and determine the effect of vitamin C intervention on protein carbonyl concentrations.

METHODS

Critically ill patients with septic shock (n = 40) were recruited, and sources of sepsis and ICU severity scores were recorded. The patients were randomised to receive either intravenous vitamin C (100 mg/kg body weight/day) or placebo infusions. Blood samples were collected at baseline and daily for up to three days for measurement of cell counts, vitamin C concentrations, protein carbonyls, C-reactive protein, and myeloperoxidase concentrations.

RESULTS

Protein carbonyl concentrations increased 2.2-fold in the cohort over the duration of the study (from 169 to 369 pmol/mg protein; p = 0.03). There were significant correlations between protein carbonyl concentrations and ICU severity scores (APACHE III r = 0.47 and SOFA r = 0.37; p < 0.05) at baseline. At study admission, the patients with pneumonia had nearly 3-fold higher protein carbonyl concentrations relative to the patients with other sources of sepsis (435 vs 157 pmol/mg protein, p < 0.0001). The septic patients had deficient vitamin C status at baseline (9.8 ± 1.4 μmol/L). This increased to 456 ± 90 μmol/L following three days of intravenous vitamin C intervention. Vitamin C intervention did not attenuate the increase in protein carbonyl concentrations.

CONCLUSIONS

Circulating protein carbonyls are specifically elevated in critically ill patients with pneumonia relative to other sources of sepsis. The reasons for this are currently unclear and may indicate a mechanism unique to pulmonary sources of sepsis. Intravenous vitamin C administration did not attenuate the increase in protein carbonyls over time.

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.

Pathogenesis of COVID-19 described through the lens of an undersulfated and degraded epithelial and endothelial glycocalyx

The glycocalyx surrounds every eukaryotic cell and is a complex mesh of proteins and carbohydrates. It consists of proteoglycans with glycosaminoglycan side chains, which are highly sulfated under normal physiological conditions. The degree of sulfation and the position of the sulfate groups mainly determine biological function. The intact highly sulfated glycocalyx of the epithelium may repel severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) through electrostatic forces. However, if the glycocalyx is undersulfated and 3-O-sulfotransferase 3B (3OST-3B) is overexpressed, as is the case during chronic inflammatory conditions, SARS-CoV-2 entry may be facilitated by the glycocalyx. The degree of sulfation and position of the sulfate groups will also affect functions such as immune modulation, the inflammatory response, vascular permeability and tone, coagulation, mediation of sheer stress, and protection against oxidative stress. The rate-limiting factor to sulfation is the availability of inorganic sulfate. Various genetic and epigenetic factors will affect sulfur metabolism and inorganic sulfate availability, such as various dietary factors, and exposure to drugs, environmental toxins, and biotoxins, which will deplete inorganic sulfate. The role that undersulfation plays in the various comorbid conditions that predispose to coronavirus disease 2019 (COVID-19), is also considered. The undersulfated glycocalyx may not only increase susceptibility to SARS-CoV-2 infection, but would also result in a hyperinflammatory response, vascular permeability, and shedding of the glycocalyx components, giving rise to a procoagulant and antifibrinolytic state and eventual multiple organ failure. These symptoms relate to a diagnosis of systemic septic shock seen in almost all COVID-19 deaths. The focus of prevention and treatment protocols proposed is the preservation of epithelial and endothelial glycocalyx integrity.

Ischemia-Reperfusion Injury in a Simulated Lung Transplant Setting Differentially Regulates Transcriptomic Profiles between Human Lung Endothelial and Epithelial Cells

Current understanding of mechanisms of ischemia-reperfusion-induced lung injury during lung preservation and transplantation is mainly based on clinical observations and animal studies. Herein, we used cell and systems biology approaches to explore these mechanisms at transcriptomics levels, especially by focusing on the differences between human lung endothelial and epithelial cells, which are crucial for maintaining essential lung structure and function. Human pulmonary microvascular endothelial cells and human lung epithelial cells were cultured to confluent, subjected to different cold ischemic times (CIT) to mimic static cold storage with preservation solution, and then subjected to warm reperfusion with a serum containing culture medium to simulate lung transplantation. Cell morphology, viability, and transcriptomic profiles were studied. Ischemia-reperfusion injury induced a CIT time-dependent cell death, which was associated with dramatic changes in gene expression. Under normal control conditions, endothelial cells showed gene clusters enriched in the vascular process and inflammation, while epithelial cells showed gene clusters enriched in protein biosynthesis and metabolism. CIT 6 h alone or after reperfusion had little effect on these phenotypic characteristics. After CIT 18 h, protein-biosynthesis-related gene clusters disappeared in epithelial cells; after reperfusion, metabolism-related gene clusters in epithelial cells and multiple gene clusters in the endothelial cells also disappeared. Human pulmonary endothelial and epithelial cells have distinct phenotypic transcriptomic signatures. Severe cellular injury reduces these gene expression signatures in a cell-type-dependent manner. Therapeutics that preserve these transcriptomic signatures may represent new treatment to prevent acute lung injury during lung transplantation.

Efficient Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) from Exhaled Breath

Severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2) is transmitted through airborne particles in exhaled breath, causing severe respiratory disease, coronavirus disease–2019 (COVID-19), in some patients. Samples for SARS-CoV-2 testing are typically collected by nasopharyngeal swab, with the virus detected by PCR; however, patients can test positive for 3 months after infection. Without the capacity to assay SARS-CoV-2 in breath, it is not possible to understand the risk for transmission from infected individuals. To detect virus in breath, the Bubbler—a breathalyzer that reverse-transcribes RNA from SARS-CoV-2 particles into a sample-specific barcoded cDNA—was developed. In a study of 70 hospitalized patients, the Bubbler was both more predictive of lower respiratory tract involvement (abnormal chest X-ray) and less invasive than alternatives. Samples tested using the Bubbler were threefold more enriched for SARS-CoV-2 RNA than were samples from tongue swabs, implying that virus particles were being directly sampled. The barcode-enabled Bubbler was used for simultaneous diagnosis in large batches of pooled samples at a lower limit of detection of 334 genomic copies per sample. Diagnosis by sequencing can provide additional information, such as viral load and strain identity. The Bubbler was configured to sample nucleic acids in water droplets circulating in air, demonstrating its potential in environmental monitoring and the protective effect of adequate ventilation.

Standard therapy of Mycobacterium avium complex pulmonary disease shows limited efficacy in an open source hollow fibre system that simulates human plasma and epithelial lining fluid pharmacokinetics

OBJECTIVES

Mycobacterium avium complex (MAC) bacteria can cause chronic pulmonary disease (PD). Current treatment regimens of azithromycin, ethambutol and rifampicin have culture conversion rates of around 65%. Dynamic, preclinical models to assess the efficacy of treatment regimens are important to guide clinical trial development. The hollow fibre system (HFS) has been applied but reports lack experimental details.

METHODS

We simulated the human pharmacokinetics of azithromycin, ethambutol and rifampicin both in plasma and epithelial lining fluid (ELF) in a HFS, exposing THP-1 cells infected with M. avium to the triple-drug regimen for 3 weeks. We accounted for drug-drug interactions and protein-binding and provide all laboratory protocols. We differentiated the effects on the intracellular and extracellular mycobacterial population.

RESULTS

The antibiotic concentrations in the HFS accurately reflected the time to peak concentration (T_max), the peak concentration (C_max) and half-life of azithromycin, rifampicin and ethambutol in plasma and ELF reported in literature. We find that plasma drug concentrations fail to hold the MAC bacterial load static (ΔLog10 CFU/mL_{Control:Regimen} = 0.66 ± 0.76 and 0.45 ± 0.28 at 3 and 21 days); ELF concentrations do hold the bacterial load static for 3 days and inhibit bacterial growth for the duration of the experiment (ΔLog10 CFU/mL_{Control:Regimen} = 1.1 ± 0.1 and 1.64 ± 0.59 at 3 and 21 days).

DISCUSSION

In our model, the current therapy against MAC is ineffective, even when accounting for antibiotic accumulation at the site of infection and intracellularly. New treatment regimens need to be developed and be compared with currently recommended regimens in dynamic models prior to clinical evaluation. With the publication of all protocols we aim to open this technology to new users.

Full-Length Recombinant hSP-D Binds and Inhibits SARS-CoV-2

SARS-CoV-2 infection of host cells is driven by binding of the SARS-CoV-2 spike-(S)-protein to lung type II pneumocytes, followed by virus replication. Surfactant protein SP-D, member of the front-line immune defense of the lungs, binds glycosylated structures on invading pathogens such as viruses to induce their clearance from the lungs. The objective of this study is to measure the pulmonary SP-D levels in COVID-19 patients and demonstrate the activity of SP-D against SARS-CoV-2, opening the possibility of using SP-D as potential therapy for COVID-19 patients. Pulmonary SP-D concentrations were measured in bronchoalveolar lavage samples from patients with corona virus disease 2019 (COVID-19) by anti-SP-D ELISA. Binding assays were performed by ELISAs. Protein bridge and aggregation assays were performed by gel electrophoresis followed by silver staining and band densitometry. Viral replication was evaluated in vitro using epithelial Caco-2 cells. Results indicate that COVID-19 patients (n = 12) show decreased pulmonary levels of SP-D (median = 68.9 ng/mL) when compared to levels reported for healthy controls in literature. Binding assays demonstrate that SP-D binds the SARS-CoV-2 glycosylated spike-(S)-protein of different emerging clinical variants. Binding induces the formation of protein bridges, the critical step of viral aggregation to facilitate its clearance. SP-D inhibits SARS-CoV-2 replication in Caco-2 cells (EC90 = 3.7 μg/mL). Therefore, SP-D recognizes and binds to the spike-(S)-protein of SARS-CoV-2 in vitro, initiates the aggregation, and inhibits viral replication in cells. Combined with the low levels of SP-D observed in COVID-19 patients, these results suggest that SP-D is important in the immune response to SARS-CoV-2 and that rhSP-D supplementation has the potential to be a novel class of anti-viral that will target SARS-CoV-2 infection.

Impact of simulated lung fluid components on the solubility of inhaled drugs and predicted in vivo performance

Orally inhaled products (OIPs) are gaining increased attention, as pulmonary delivery is a preferred route for the treatment of various diseases. Yet, the field of inhalation biopharmaceutics is still in development phase. For a successful correlation between various in vitro data obtained during formulation characterization and in vivo performance, it is necessary to understand the impact of parameters such as solubility and dissolution of drugs. In this work, we used in vitro-in silico feedback-feedforward approach to gain a better insight into the biopharmaceutics behavior of inhaled Salbutamol Sulphate (SS) and Budesonide (BUD). The thorough characterization of the in vitro test media and the impact of different in vitro fluid components such as lipids and protein on the solubility of aforementioned drugs was studied. These results were subsequently used as an input into the developed in silico models to investigate potential PK parameter changes in vivo. Results revealed that media comprising lipids and albumin were the most biorelevant and impacted the solubility of BUD the most. On the contrary, no notable impact was seen in case of SS. The use of simple media such as phosphate buffer saline (PBS) might be sufficient to use in solubility studies of the highly soluble and permeable drugs. However, its use for the poorly soluble drugs is limited due to the greater potential for interactions within in vivo environment. The use of in silico tools showed that the model response varies, depending on the used media. Therefore, this work highlights the relevance of carefully selecting the media composition when investigating solubility and dissolution behavior, especially in the early phases of drug development and of poorly soluble drugs.

Dynamic interactions and intracellular fate of label-free, thin graphene oxide sheets within mammalian cells: role of lateral sheet size

Graphene oxide (GO) holds great potential for biomedical applications, however fundamental understanding of the way it interacts with biological systems is still lacking even though it is essential for successful clinical translation. In this study, we exploit intrinsic fluorescent properties of thin GO sheets to establish the relationship between lateral dimensions of the material, its cellular uptake mechanisms and intracellular fate over time. Label-free GO with distinct lateral dimensions, small (s-GO) and ultra-small (us-GO) were thoroughly characterised both in water and in biologically relevant cell culture medium. Interactions of the material with a range of non-phagocytic mammalian cell lines (BEAS-2B, NIH/3T3, HaCaT, 293T) were studied using a combination of complementary analytical techniques (confocal microscopy, flow cytometry and TEM). The uptake mechanism was initially interrogated using a range of pharmaceutical inhibitors and validated using polystyrene beads of different diameters (0.1 and 1 μm). Subsequently, RNA-Seq was used to follow the changes in the uptake mechanism used to internalize s-GO flakes over time. Regardless of lateral dimensions, both types of GO were found to interact with the plasma membrane and to be internalized by a panel of cell lines studied. However, s-GO was internalized mainly via macropinocytosis while us-GO was mainly internalized via clathrin- and caveolae-mediated endocytosis. Importantly, we report the shift from macropinocytosis to clathrin-dependent endocytosis in the uptake of s-GO at 24 h, mediated by upregulation of mTORC1/2 pathway. Finally, we show that both s-GO and us-GO terminate in lysosomal compartments for up to 48 h. Our results offer an insight into the mechanism of interaction of GO with non-phagocytic cell lines over time that can be exploited for the design of biomedically-applicable 2D transport systems.

Protein and Microbial Biomarkers in Sputum Discern Acute and Latent Tuberculosis in Investigation of Pastoral Ethiopian Cohort

Differential diagnosis of tuberculosis (TB) and latent TB infection (LTBI) remains a public health priority in high TB burden countries. Pulmonary TB is diagnosed by sputum smear microscopy, chest X-rays, and PCR tests for distinct Mycobacterium tuberculosis (Mtb) genes. Clinical tests to diagnose LTBI rely on immune cell stimulation in blood plasma with TB-specific antigens followed by measurements of interferon-γ concentrations. The latter is an important cytokine for cellular immune responses against Mtb in infected lung tissues. Sputum smear microscopy and chest X-rays are not sufficiently sensitive while both PCR and interferon-γ release assays are expensive. Alternative biomarkers for the development of diagnostic tests to discern TB disease states are desirable. This study's objective was to discover sputum diagnostic biomarker candidates from the analysis of samples from 161 human subjects including TB patients, individuals with LTBI, negative community controls (NCC) from the province South Omo, a pastoral region in Ethiopia. We analyzed 16S rRNA gene-based bacterial taxonomies and proteomic profiles. The sputum microbiota did not reveal statistically significant differences in α-diversity comparing the cohorts. The genus Mycobacterium, representing Mtb, was only identified for the TB group which also featured reduced abundance of the genus Rothia in comparison with the LTBI and NCC groups. Rothia is a respiratory tract commensal and may be sensitive to the inflammatory milieu generated by infection with Mtb. Proteomic data supported innate immune responses against the pathogen in subjects with pulmonary TB. Ferritin, an iron storage protein released by damaged host cells, was markedly increased in abundance in TB sputum compared to the LTBI and NCC groups, along with the α-1-acid glycoproteins ORM1 and ORM2. These proteins are acute phase reactants and inhibit excessive neutrophil activation. Proteomic data highlight the effector roles of neutrophils in the anti-Mtb response which was not observed for LTBI cases. Less abundant in the sputum of the LTBI group, compared to the NCC group, were two immunomodulatory proteins, mitochondrial TSPO and the extracellular ribonuclease T2. If validated, these proteins are of interest as new biomarkers for diagnosis of LTBI.

Air particulate matter pollution and circulating surfactant protein: A systemic review and meta-analysis

OBJECTIVE

Air particulate matter (PM) pollution is associated with the alterations in circulating pulmonary damage proteins. But there are not consistent results among the epidemiological studies. The aim of this study is to investigate the alteration of surfactant protein (SP) from PM exposure.

METHODS

We conducted a comprehensive meta-analysis by searching the databases of PubMed, Medline, EMBASE, Web of Science and CNKI before October 2020 which reported PM pollutants and surfactant protein in the population. The sources of heterogeneity were assessed by subgroup (smoking, particulate matter with different aerodynamic diameter, exposure duration) analysis. We also used the publication bias tests for the comprehensive assessment.

RESULTS

This meta-analysis consisted of 10 studies with 1985 subjects. The results showed that the combined standardized mean difference (SMD) value was 0.05, 95% confidence interval (CI) was -0.07 to 0.17 for serum SP-A and -0.81 (95% CI: -1.41 to -0.21) for circulating SP-D. Among smokers, the combined SMD value of SP-A were 0.29 (95% CI: 0.05 to 0.52). We did not find the correlation between publication year of SP-A and SP-D and study heterogeneity.

CONCLUSIONS

Circulating SP-D was significantly decreased by air particulate matter. Serum SP-A was significantly increased by PM exposure among smokers. Circulating surfactant protein may be considered as a biomarker for respiratory injury caused by air particulate matter.

Development of a multiplex mass spectrometry method for simultaneous quantification of urinary proteins related to respiratory health

Respiratory health of children is a health priority. Club cell protein (CC16) is an interesting biomarker of lung diseases and adverse effects towards the airway epithelium integrity. Osteopontin (OPN) and nuclear factor-kappa B (NF-κB) also play a role in respiratory health. The use of urine as biomarker source is useful in studies involving children but necessitates proper adjustment for physiological confounders influencing the urinary excretion, potentially characterized with beta-2-microglobulin (β2M), retinol binding protein 4 (RBP4) or myoglobin (MYO), as well as adjustment for possible renal dysfunction, characterized by human serum albumin (HSA). The simultaneous quantification of all these proteins in urine could facilitate children's health monitoring. A multiple reaction monitoring method (MRM) was developed and validated for the relative quantification of the seven mentioned urinary proteins. A total of nine proteotypic peptides were selected and used for the relative quantification of the seven proteins. The MRM method was completely validated for all proteins and partially for OPN. LOQ's ranged from 0.3 to 42.8 ng/ml, a good reproducibility and a good linearity were obtained across the analytical measurement range (r² > 0.98). The method yielded varying correlations (r² of 0.78, 0.71, 0.34 and 0.15 for CC16, β2M, RBP4 and HSA respectively) with available immunoassay data. It also allowed the identification and successful quantification of β2M and RBP4 as a protein candidate for adjustment of renal handling and dysfunction. All proteins were detected in the urine samples except for MYO and NF-κB. Our validated MRM-method is able to simultaneously quantify in urine biomarkers of airway epithelium integrity and biomarkers of variation in renal function and urinary dilution. This will allow to investigate further in future studies if urine can be used as a good surrogate source for biomarkers of airway epithelium integrity, and to understand the complex relationship between cause and effect in children's respiratory health monitoring.

The potential of biomarkers of fibrosis in chronic lung allograft dysfunction

Chronic lung allograft dysfunction (CLAD) is the major long-term cause of morbidity and mortality after lung transplantation. Both bronchiolitis obliterans syndrome and restrictive lung allograft syndrome, two main types of CLAD, lead to fibrosis in either the small airways or alveoli and pleura. Pathological pathways in CLAD and other types of fibrosis, for example idiopathic pulmonary fibrosis, are assumed to overlap and therefore fibrosis biomarkers could aid in the early detection of CLAD. These biomarkers could help to differentiate between different phenotypes of CLAD and could, in comparison to biomarkers of inflammation, possibly distinguish an infectious event from CLAD when a decline in lung function is present. This review gives an overview of known CLAD specific biomarkers, describes new promising fibrosis biomarkers currently investigated in other types of fibrosis, and discusses the possible use of these fibrosis biomarkers for CLAD.

Optimization of an air-liquid interface in vitro cell co-culture model to estimate the hazard of aerosol exposures

Inhalation exposure to environmental and occupational aerosol contaminants is associated with many respiratory health problems. To realistically mimic long-term inhalation exposure for toxicity testing, lung epithelial cells need to maintained and exposed under air-liquid interface (ALI) conditions for a prolonged period of time. In addition, to study cellular responses to aerosol particles, lung epithelial cells have to be co-cultured with macrophages. To that aim, we evaluated human bronchial epithelial Calu-3, 16HBE14o- (16HBE), H292, and BEAS-2B cell lines with respect to epithelial morphology, barrier function and cell viability under prolonged ALI culture conditions. Only the Calu-3 cells can retain the monolayer structure and maintain a strong tight junction under long-term ALI culture at least up to 2 weeks. As such, Calu-3 cells were applied as the structural barrier to create co-culture models with human monocyte-derived macrophages (MDMs) and THP-1 derived macrophages (TDMs). Adhesion of macrophages onto the epithelial monolayer was allowed for 4 h with a density of 5 × 10⁴ macrophages/cm². In comparison to the Calu-3 mono-culture model, Calu-3 + TDM and Calu-3 + MDM co-culture models showed an increased sensitivity in inflammatory responses to lipopolysaccharide (LPS) aerosol at Day 1 of co-culture, with the Calu-3 + MDM model giving a stronger response than Calu-3 + TDM. Therefore, the epithelial monolayer integrity and increased sensitivity make the Calu-3 + MDM co-culture model a preferred option for ALI exposure to inhaled aerosols for toxicity testing.

Club Cell Protein 16 Attenuates CD16brightCD62dim Immunosuppressive Neutrophils in Damaged Tissue upon Posttraumatic Sepsis-Induced Lung Injury

Background

Recently, identification of immunosuppressive polymorphonuclear leukocytes (PMNL) that were traditionally described as proinflammatory cells emerged in the field of posttraumatic immunity. To understand their local and remote distribution after trauma, PMNL-subsets and the impact of immunomodulatory Club Cell protein (CC)16 that correlates with pulmonary complications were assessed.

Methods

C57BL/6N mice were divided into three groups, receiving isolated blunt chest trauma (TxT), undergoing TxT followed by cecal ligation and puncture (CLP, TxT + CLP) after 24 h, or sham undergoing analgosedation (n = 18/group). Further, each group was subdivided into three groups receiving either no treatment (ctrl) or intratracheal neutralization of CC16 by application of anti-CC16-antibody or application of an unspecific IgG control antibody (n = 6/group). Treatment was set at the time point after TxT. Analyses followed 6 h post-CLP. PMNL were characterized via expression of CD11b, CD16, CD45, CD62L, and Ly6G by flow cytometry in bone marrow (BM), blood, spleen, lung, liver, and bronchoalveolar and peritoneal lavage fluid (BALF and PL). Apoptosis was assessed by activated (cleaved) caspase-3. Results from untreated ctrl and IgG-treated mice were statistically comparable between all corresponding sham, TxT, and TxT + CLP groups.

Results

Immature (CD16^dimCD62L^bright) PMNL increased significantly in BM, circulation, and spleen after TxT vs. sham and were significantly attenuated in the lungs, BALF, PL, and liver. Classical-shaped (CD16^brightCD62L^bright) PMNL increased after TxT vs. sham in peripheral tissue and were significantly attenuated in circulation, proposing a trauma-induced migration of mature or peripheral differentiation of circulating immature PMNL. Immunosuppressive (CD16^brightCD62L^dim) PMNL decreased significantly in the lungs and spleen, while they systemically increased after TxT vs. sham. CLP in the TxT + CLP group reduced immunosuppressive PMNL in PL and increased their circulatory rate vs. isolated TxT, showing local reduction in affected tissue and their increase in nonaffected tissue. CC16 neutralization enhanced the fraction of immunosuppressive PMNL following TxT vs. sham and decreased caspase-3 in the lungs post-CLP in the TxT + CLP group, while apoptotic cells in the liver diminished post-TxT. Posttraumatic CC16 neutralization promotes the subset of immunosuppressive PMNL and antagonizes their posttraumatic distribution.

Conclusion

Since CC16 affects both the distribution of PMNL subsets and apoptosis in tissues after trauma, it may constitute as a novel target to beneficially shape the posttraumatic tissue microenvironment and homeostasis to improving outcomes.

Naphthalene: irritative and inflammatory effects on the airways

Objective

This cross-sectional study determined whether acute sensory irritative or (sub)chronic inflammatory effects of the eyes, nose or respiratory tract are observed in employees who are exposed to naphthalene at the workplace.

Methods

Thirtynine healthy and non-smoking male employees with either moderate (n = 22) or high (n = 17) exposure to naphthalene were compared to 22 male employees from the same plants with no or only rare exposure to naphthalene. (Sub)clinical endpoint measures included nasal endoscopy, smell sensitivity, self-reported work-related complaints and the intensity of naphthalene odor and irritation. In addition, cellular and soluble mediators in blood, nasal lavage fluid (NALF) and induced sputum (IS) were analysed. All measurements were carried out pre-shift on Monday and post-shift on Thursday. Personal air monitoring revealed naphthalene shift concentrations up to 11.6 mg/m³ with short-term peak concentrations up to 145.8 mg/m³ and 1- and 2-naphthol levels (sum) in post-shift urine up to 10.1 mg/L.

Results

Acute sensory irritating effects at the eyes and upper airways were reported to occur when directly handling naphthalene (e.g., sieving pure naphthalene). Generally, naphthalene odor was described as intense and unpleasant. Habituation effects or olfactory fatigue were not observed. Endoscopic examination revealed mild inflammatory effects at the nasal mucosa of exposed employees in terms of reddening and swelling and abnormal mucus production. No consistent pattern of cellular and soluble mediators in blood, NALF or IS was observed which would indicate a chronic or acute inflammatory effect of naphthalene in exposed workers.

Conclusions

The results suggest that exposure to naphthalene induces acute sensory irritative effects in exposed workers. No (sub)chronic inflammatory effects on the nasal epithelium or the respiratory tract could be observed under the study conditions described here.

Polycyclic aromatic hydrocarbons in particulate matter and serum club cell secretory protein change among schoolchildren: A molecular epidemiology study

Airborne particulate matter (PM) is a complex mixture containing various kinds of harmful components. Exposure to air PM is associated with childhood respiratory disease, but epidemiological data are limited concerning the circulating respiratory injury protein on the etiology of childhood respiratory disease. Specifically, the role of PM toxic components or its biological effective dose (adduct) in respiratory injury remains unclear. To demonstrate the dose-response relationship and the main mechanism on circulating club cell secretory protein (CC16) from PM compositions among children, we enrolled 273 boarding schoolchildren in China, including 110 and 163 children of whom were in the low- and high-PM exposed areas, respectively. In this study, we measured the internal exposure levels, including serum polycyclic aromatic hydrocarbons (PAH) adduct, urinary metals, and AhR expression, and detected the serum CC16 level as a lung injury marker. Environmental tobacco exposure in children was assessed by urinary cotinine. We found that significantly higher levels of serum CC16, benzo[a]pyridin-7,8-dihydroglycol-9,10-epoxide (BPDE)-albumin adduct, urinary molybdenum, selenium, arsenic, cadmium and barium, and lower level of AhR expression in high-PM exposed group. There was a good association between serum BPDE-albumin adduct and CC16 (β = 0.222, P = 0.006). There was no association on urinary metals and serum CC16. BPDE-albumin adduct was directly associated with serum CC16 alternation [direct effect = 0.2044, 95% confidence interval (CI) = (0.0426, 0.36)]. PM could cause serum CC16 increased in children. PAH and its adduct might play a key role in lung injury during PM exposure.

A molecular cell atlas of the human lung from single-cell RNA sequencing

Although single-cell RNA sequencing studies have begun to provide compendia of cell expression profiles1-9, it has been difficult to systematically identify and localize all molecular cell types in individual organs to create a full molecular cell atlas. Here, using droplet- and plate-based single-cell RNA sequencing of approximately 75,000 human cells across all lung tissue compartments and circulating blood, combined with a multi-pronged cell annotation approach, we create an extensive cell atlas of the human lung. We define the gene expression profiles and anatomical locations of 58 cell populations in the human lung, including 41 out of 45 previously known cell types and 14 previously unknown ones. This comprehensive molecular atlas identifies the biochemical functions of lung cells and the transcription factors and markers for making and monitoring them; defines the cell targets of circulating hormones and predicts local signalling interactions and immune cell homing; and identifies cell types that are directly affected by lung disease genes and respiratory viruses. By comparing human and mouse data, we identified 17 molecular cell types that have been gained or lost during lung evolution and others with substantially altered expression profiles, revealing extensive plasticity of cell types and cell-type-specific gene expression during organ evolution including expression switches between cell types. This atlas provides the molecular foundation for investigating how lung cell identities, functions and interactions are achieved in development and tissue engineering and altered in disease and evolution.

Inorganic chloramines: a critical review of the toxicological and epidemiological evidence as a basis for occupational exposure limit setting

Inorganic chloramines are not commercially available, but monochloramine is produced in situ for disinfection or for use in chemical synthesis. Inorganic chloramines are also formed when free chlorine reacts with nitrogen containing substances, e.g. ammonia and urea, present in chlorinated water sources. Occupational exposure may, therefore, occur in e.g. swimming pool facilities and the food processing industry. Monochloramine is soluble and stable in water and the dominating inorganic chloramine in chlorinated water sources. No clinical effects were seen in healthy volunteers given monochloramine in drinking water during 4 or 12 weeks in doses of 0.043 or 0.034 mg/kg bw/day, respectively. Limited data indicate that monochloramine is weakly mutagenic in vitro but not genotoxic in vivo. One drinking water study indicated equivocal evidence of carcinogenicity in female rats but not in male rats and mice. No reproductive or developmental effects were shown in rodents in the few studies located. Dichloramine is soluble but unstable in water. In the only study located, mild histological effects in kidneys, thyroid and gastric cardia were observed in rats administered dichloramine in drinking water for 13 weeks. Trichloramine is immiscible with water and evaporates easily from water into air. Therefore, the primary exposure route of concern in the occupational setting is inhalation. Occupational exposure to trichloramine has been demonstrated in indoor swimming pool facilities and in the food processing industry where chlorinated water is used for disinfection. Exposure-response relationships between airborne levels and self-reported ocular and upper airway irritation have been shown in several studies. Exposure to trichloramine may aggravate asthma symptoms in individuals with existing asthma. The risk of developing asthma following long-term exposure to trichloramine cannot be evaluated at present. No data on genotoxic, carcinogenic, reproductive or developmental effects were located. The toxicological data for mono- and dichloramine are insufficient to recommend health-based occupational exposure limits (OELs).As regard trichloramine, the critical effect is judged to be irritation observed in several studies on pool workers, starting at approximately 0.4 mg/m³ (stationary sampling). Based on these data, a health-based OEL of 0.1 mg/m³ (8-h time-weighted average) is recommended. This corresponds to 0.2 mg/m³ for stationary measurements in swimming pool facilities. No short-term exposure limit (STEL) is recommended.

Gender-dependent association between exhaled nitric oxide and the CC16 38AA genotype in young school children

Background

Studies that investigated the association between the CC16 A38G polymorphism and the risk of asthma yielded conflicting results. The aim of this study among schoolchildren was to assess the relationships of CC16 A38G polymorphism with aeroallergen sensitization and fractional exhaled nitric oxide (FeNO), two outcomes predicting asthma later in life.

Methods

The study included 139 children (72 boys), median age of 7.7. Information on each child's health, lifestyle, and environment was collected through a questionnaire completed by their parents. CC16 genotypes were determined using urinary DNA. We measured FeNO, the CC16 protein in urine and nasal lavage fluid and aeroallergen‐specific immunoglobulin E in nasal mucosa fluid.

Results

Children with the homozygous mutant CC16 38AA genotype had higher odds of increased FeNO (>30 ppb) compared with their peers with the wild‐type genotype 38GG (OR, 9.85; 95% CI, 2.09‐46.4; P = .004). This association was female gender specific (P = .002) not being observed in boys (P = .40). It was also independent of allergic sensitization, which yet emerged as the strongest predictor of FeNO along with the use of bleach for house cleaning. Children with the CC16 38AA genotype had lower covariates‐adjusted urinary CC16 levels than those with 38GG (median, μg/L, 1.17 vs 2.08, P = .02).

Conclusion

Our study suggests that the CC16 38AA allele promotes airway inflammation as measured by FeNO through a gender‐dependent association. Deficient levels of CC16 in the deep lung, measured noninvasively in urine, as a possible proxy for serum CC16, might underlie this promoting effect.

Change in Serum Biomarker CA 15-3 as an Early Predictor of Response to Treatment and Survival in Hypersensitivity Pneumonitis

BACKGROUND

Hypersensitivity pneumonitis (HP) is an interstitial lung disease with a heterogeneous course of disease and treatment response. Cancer antigen 15-3 (CA 15-3), part of mucin 1, is believed to reflect epithelial cell injury and lung permeability and could be a potential biomarker for treatment response in HP.

OBJECTIVE

To assess the value of CA 15-3 as a predictive biomarker in non-fibrotic and fibrotic HP during immunosuppressive therapy.

DESIGN

Serum levels of CA 15-3 and pulmonary function tests (PFTs) were retrospectively retrieved from 48 HP patients treated with prednisone or cyclophosphamide at initiation of therapy (baseline), after 3 and 6 months. Pearson's correlation coefficient was computed to assess correlations between change in serum levels and PFT. Survival was evaluated using Kaplan-Meier curves.

RESULTS

After 6 months of immunosuppressive therapy CA 15-3 levels decreased significantly compared to baseline (p = 0.001). Change in CA 15-3 after 6 months correlated with FVC change (r =  - 0.469; p = 0.001). Correlations with FVC change were observed in prednisone-treated HP (r =  - 0.514; p = 0.005) and fibrotic HP (r =  - 0.417; p = 0.007). Three-month CA 15-3 change correlated with 6-month FVC change (r =  - 0.599; p < 0.001). CA 15-3 declines of at least 7.9% after 6 months were associated with increased survival compared to minor CA 15-3 changes (HR 0.34; p = 0.020).

CONCLUSION

Serum CA 15-3 correlates with PFT during 6 months of immunosuppressive therapy in HP. Interestingly, early CA 15-3 changes could predict future PFT. Furthermore, a decrease in CA 15-3 is related to longer survival. Therefore, serum CA 15-3 is a promising biomarker for implementation in HP care.

A retrospective clinical research of relapsed organizing pneumonia

BACKGROUND

Organizing pneumonia (OP) usually responds spectacularly well to initial treatment, but relapses can occur and some cases run a fatal course. Still, the issue of relapse has been addressed in relatively few studies, and predictors have not been clarified. The purpose of this study was to examine the pattern of relapses in OP, to determine whether relapse affects morbidity and mortality, and to identify possible predictors of relapse.

METHODS

Blood sampling, pulmonary function testing, computed tomography (CT) of the chest, and bronchofiberscopy were performed for all patients and were retrospectively reviewed along with clinical information. Periodical chest CT was conducted and additional chest CT was performed when relapse of OP was clinically suspected. All patients were followed regarding treatment response, treatment duration, and presence of relapse. Results were compared between two groups based on serum concentrations of surfactant protein (SP)-D: normal SP-D and high SP-D.

RESULTS

Twenty-two patients were analyzed in this study. SP-D showed a negative correlation with percutaneous oxygen saturation and positive correlations with serum lactate dehydrogenase, Krebs von den Lungen (KL)-6, and percentage of lymphocytes in bronchoalveolar lavage (BAL). Prognosis was good for all patients, but relapse was significantly more frequent in the high SP-D group (6 cases) than in the normal SP-D group (0 cases; P = 0.049). Serum KL-6 and percentage of monocytes in BAL were significantly higher, and pulmonary vital capacity and forced expiratory volume in 1 s were significantly lower in the high SP-D group than in the low SP-D group.

CONCLUSIONS

When treating cases of OP with high serum concentrations of SP-D, attention should be paid to the possibility of relapse.

Short halt in vaping modifies cardiorespiratory parameters and urine metabolome: a randomized trial

Propylene glycol and glycerol are e-cigarette constituents that facilitate liquid vaporization and nicotine transport. As these small hydrophilic molecules quickly cross the lung epithelium, we hypothesized that short-term cessation of vaping in regular users would completely clear aerosol deposit from the lungs and reverse vaping-induced cardiorespiratory toxicity. We aimed to assess the acute effects of vaping and their reversibility on biological/clinical cardiorespiratory parameters [serum/urine pneumoproteins, hemodynamic parameters, lung-function test and diffusing capacities, transcutaneous gas tensions (primary outcome), and skin microcirculatory blood flow]. Regular e-cigarette users were enrolled in this randomized, investigator-blinded, three-period crossover study. The periods consisted of nicotine-vaping (nicotine-session), nicotine-free vaping (nicotine-free-session), and complete cessation of vaping (stop-session), all maintained for 5 days before the session began. Multiparametric metabolomic analyses were used to verify subjects' protocol compliance. Biological/clinical cardiorespiratory parameters were assessed at the beginning of each session (baseline) and after acute vaping exposure. Compared with the nicotine- and nicotine-free-sessions, a specific metabolomic signature characterized the stop-session. Baseline serum club cell protein-16 was higher during the stop-session than the other sessions (P < 0.01), and heart rate was higher in the nicotine-session (P < 0.001). Compared with acute sham-vaping in the stop-session, acute nicotine-vaping (nicotine-session) and acute nicotine-free vaping (nicotine-free-session) slightly decreased skin oxygen tension (P < 0.05). In regular e-cigarette-users, short-term vaping cessation seemed to shift baseline urine metabolome and increased serum club cell protein-16 concentration, suggesting a decrease in lung inflammation. Additionally, acute vaping with and without nicotine decreased slightly transcutaneous oxygen tension, likely as a result of lung gas exchanges disturbances.

Valuable Serum Markers in Pulmonary Alveolar Proteinosis

Objective

Several serum markers were reported to reflect the severity of pulmonary alveolar proteinosis (PAP). The aim of this study is to investigate a reliable and facile marker to access and monitor the clinical course of PAP in a large cohort.

Methods

PAP patients from January 2010 to June 2018 were enrolled. Hospital records were used as data sources. The levels of various serum indicators were detected. We evaluated the correlation between pulmonary function test results and clinical variables.

Results

Diffusion capacity for carbon monoxide (DLCO) level was positively correlated with the level of high-density lipoprotein cholesterol (HDL-C) (P < 0.05) in 122 patients of PAP at baseline. The levels of HDL-C and DLCO significantly increased while carcinoembryonic antigen (CEA), CYFRA21-1, neuron-specific enolase (NSE), and lactic dehydrogenase (LDH) levels decreased six months after granulocyte-macrophage colony-stimulating factor (GM-CSF) inhalation therapy between 14 patients with PAP. Nevertheless, the increased DLCO was significantly correlated with decreased CEA (r = ‐0.579, P = 0.031) and CYFRA 21-1 (r = ‐0.632, P = 0.015). In 10 PAP patients without GM-CSF inhalation therapy, HDL-C and DLCO significantly decreased while NSE and LDH levels increased after six months of follow-up. The decreased DLCO was significantly correlated with increased LDH (r = ‐0.694, P = 0.026).

Conclusions

Serum CEA, CYFRA21-1, and LDH are valuable serum markers for the evaluation of disease activity of PAP and may predict the response to treatment of PAP.