A critical review of the use of Clara cell secretory protein (CC16) as a biomarker of acute or chronic pulmonary effects

Comparison of volume-controlled ventilation, pressure-controlled ventilation and pressure-controlled ventilation-volume guaranteed in infants and young children in the prone position: A prospective randomized study

STUDY OBJECTIVE

To explore if the pressure-controlled ventilation (PCV) and pressure-controlled ventilation-volume guaranteed (PCV-VG) modes are superior to volume-controlled ventilation (VCV) in optimizing intraoperative respiratory mechanics in infants and young children in the prone position.

DESIGN

A single-center prospective randomized study.

SETTING

Children's Hospital, Zhejiang University School of Medicine.

PATIENTS

Pediatric patients aged 1 month to 3 years undergoing elective spinal cord detethering surgery.

INTERVENTIONS

Patients were randomly allocated to the VCV group, PCV group and PCV-VG group. The target tidal volume (VT) was 8 mL/kg and the respiratory rate (RR) was adjusted to maintain a constant end tidal CO2.

MEASUREMENTS

The primary outcome was intraoperative peak airway pressure (Ppeak). Secondary outcomes included other respiratory and ventilation variables, gas exchange values, serum lung injury biomarkers concentration, hemodynamic parameters and postoperative respiratory complications.

MAIN RESULTS

A total of 120 patients were included in the final analysis (40 in each group). The VCV group showed higher Ppeak at T2 (10 min after prone positioning) and T3 (30 min after prone positioning) than the PCV and PCV-VG groups (T2: P = 0.015 and P = 0.002, respectively; T3: P = 0.007 and P = 0.009, respectively). The prone-related decrease in dynamic compliance was prevented by PCV and PCV-VG ventilation modalities at T2 and T3 than by VCV (T2: P = 0.008 and P = 0.015, respectively; T3: P = 0.015 and P = 0.014, respectively). Additionally, there were no significant differences in other secondary outcomes among the three groups.

CONCLUSION

In infants and young children undergoing spinal cord detethering surgery in the prone position, PCV-VG may be a better ventilation mode due to its ability to mitigate the increase in Ppeak and decrease in Cdyn while maintaining consistent VT.

Club cell protein (CC16) in serum as an effect marker for small airway epithelial damage caused by diesel exhaust and blasting fumes in potash mining

OBJECTIVE

The effect marker club cell protein (CC16) is secreted by the epithelium of the small respiratory tract into its lumen and passes into the blood. Increased amounts of CC16 in serum are observed during acute epithelial lung injury due to air pollutants. CC16 in serum was determined as part of this cross-sectional study in underground potash miners on acute and chronic health effects from exposures to diesel exhaust and blasting fumes.

METHODS

Nitrogen oxides, carbon monoxide, and diesel particulate matter were measured in 672 workers at a German potash mining site on a person-by-person basis over an early shift or midday shift, together with CC16 serum concentrations before and after the respective shift. CC16 concentrations and CC16 shift-differences were evaluated with respect to personal exposure measurements and other quantitative variables by Spearman rank correlation coefficients. CC16 shift-differences were modeled using multiple linear regression. Above-ground workers as reference group were compared to the exposed underground workers.

RESULTS

Serum concentrations of CC16 were influenced by personal characteristics such as age, smoking status, and renal function. Moreover, they showed a circadian rhythm. While no statistically significant effects of work-related exposure on CC16 concentrations were seen in never smokers, such effects were evident in current smokers.

CONCLUSION

The small airways of current smokers appeared to be vulnerable to the combination of measured work-related exposures and individual exposure to smoking. Therefore, as health protection of smokers exposed to diesel exhaust and blasting fumes, smoking cessation is strongly recommended.

Associations of Serum Clara Cell Protein 16 with Severity and Prognosis in Adults with Community-Acquired Pneumonia

Background

Clara cell protein 16 (CC16) has multiple functions, including antioxidant, anti-inflammatory, and immune regulation properties. Nevertheless, the concrete function of CC16 in adult patients with community-acquired pneumonia (CAP) remained blurred.

Methods

A total of 541 adult patients with CAP were recruited on admission. Peripheral blood specimens, clinical parameters, and demographic characteristics were collected. The concentration of serum CC16 was evaluated through ELISA. The relationships between serum CC16 and clinical parameters were appraised by Spearman or Pearson correlative analyses. The correlations of serum CC16 with severity and prognosis were assessed using linear or logistic regression models.

Results

The level of CC16 was gradually decreased across with the elevated severity scores system of CAP. After treatment, the level of serum CC16 was upregulated. Correlative analyses found that serum CC16 was negatively related to inflammatory cytokines. Additionally, multivariate linear and logistic regression models revealed that serum CC16 was inversely associated with severity scores system. In addition, reduced serum CC16 on admission elevated the risks of vasoactive agent usage, ICU admission, and death during hospitalization. We observed an almost discriminatory ability for severity and death between serum CC16 and severity scores system, and were all obviously elevated compared to routine inflammatory and infectious markers.

Conclusion

There are substantially inverse correlations between serum CC16 level on admission with severity scores and poorly prognostic outcomes, indicating that CC16 is involved in the pathophysiological process of CAP. This study is helpful for establishing the potential application of serum CC16 in risk evaluation and targeted treatment.

Circulating CC16 and Asthma: A Population-based, Multicohort Study from Early Childhood through Adult Life

Rationale: Club cell secretory protein (CC16) is an antiinflammatory protein highly expressed in the airways. CC16 deficiency has been associated with lung function deficits, but its role in asthma has not been established conclusively. Objectives: To determine 1) the longitudinal association of circulating CC16 with the presence of active asthma from early childhood through adult life and 2) whether CC16 in early childhood predicts the clinical course of childhood asthma into adult life. Methods: We assessed the association of circulating CC16 and asthma in three population-based birth cohorts: the Tucson Children's Respiratory Study (years 6-36; total participants, 814; total observations, 3,042), the Swedish Barn/Children, Allergy, Milieu, Stockholm, Epidemiological survey (years 8-24; total participants, 2,547; total observations, 3,438), and the UK Manchester Asthma and Allergy Study (years 5-18; total participants, 745; total observations, 1,626). Among 233 children who had asthma at the first survey in any of the cohorts, baseline CC16 was also tested for association with persistence of symptoms. Measurements and Main Results: After adjusting for covariates, CC16 deficits were associated with increased risk for the presence of asthma in all cohorts (meta-analyzed adjusted odds ratio per 1-SD CC16 decrease, 1.20; 95% confidence interval [CI], 1.12-1.28; P < 0.0001). The association was particularly strong for asthma with frequent symptoms (meta-analyzed adjusted relative risk ratio, 1.40; 95% CI, 1.24-1.57; P < 0.0001), was confirmed for both atopic and nonatopic asthma, and was independent of lung function impairment. After adjustment for known predictors of persistent asthma, children with asthma in the lowest CC16 tertile had a nearly fourfold increased risk for having frequent symptoms persisting into adult life compared with children with asthma in the other two CC16 tertiles (meta-analyzed adjusted odds ratio, 3.72; 95% CI, 1.78-7.76; P < 0.0001). Conclusions: Circulating CC16 deficits are associated with the presence of asthma with frequent symptoms from childhood through midadult life and predict the persistence of asthma symptoms into adulthood. These findings support a possible protective role of CC16 in asthma and its potential use for risk stratification.

Levels of Clara cell secretory protein and surfactant protein A in municipal solid waste management workers in Ibadan, Southwest Nigeria

Toxic pneumonitis and related respiratory symptoms are common among waste management workers (WMWs). Products of different cellular responses following exposure to toxic components of wastes can lead to the production of a variety of biomolecules. There is a growing recognition of the importance of biomarkers in risk assessment and a strong advocacy for their determination and use as indicators of health and safety. This study assessed the prevalence of respiratory symptoms and the relevance of pulmonary surfactant protein A (SP-A) and Clara cell 16 protein (CC16) as indicators of occupational inhalation exposure to toxic substances and irritants in WMW. A total of 172 subjects consisting of 112 WMWs and 60 Non-WMWs were recruited by purposive sampling. Data on socio-economic and work-related symptoms were collected using structured questionnaire. CC16 and SP-A were determined by ELISA in serum samples. Clinical history reveals a slightly higher prevalence of respiratory symptoms in WMWs relative to control subjects. Increased permeability of the lung-blood barrier, characterized by significant elevation of serum SP-A and serum CC16, was associated with respiratory symptoms in WMWs. Steady increases in SP-A and CC16, respectively, in relation to occupational duration were observed in WMWs relative to control. Receiver operating characteristic curve and multivariate analyses revealed SP-A and CC16 as important lung biomarkers for assessing sub-clinical effects of occupational exposure. Our data suggest SP-A and CC16 may be relevant indicators for assessing occupational inhalation exposure to toxic substances and irritants among WMWs.

Circulating Pulmonary-Originated Epithelial Biomarkers for Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis

Previous studies have found several biomarkers for acute respiratory distress syndrome (ARDS), but the accuracy of most biomarkers is still in doubt due to the occurrence of other comorbidities. In this systematic review and meta-analysis, we aimed to explore ideal ARDS biomarkers which can reflect pathophysiology features precisely and better identify at-risk patients and predict mortality. Web of Science, PubMed, Embase, OVID, and the Cochrane Library were systematically searched for studies assessing the reliability of pulmonary-originated epithelial proteins in ARDS. A total of 32 studies appeared eligible for meta-analysis, including 2654 ARDS/ALI patients in this study. In the at-risk patients' identification group, the highest pooled effect size was observed in Krebs von den Lungren-6 (KL-6) (SMD: 1.17 [95% CI: 0.55, 1.79]), followed by club cell proteins 16 (CC16) (SMD: 0.74 [95% CI: 0.01, 1.46]), and surfactant proteins-D (SP-D) (SMD: 0.71 [95% CI: 0.57, 0.84]). For the mortality prediction group, CC16 exhibited the largest effect size with SMD of 0.92 (95% CI: 0.42, 1.43). Meanwhile, the summary receiver operating characteristic (SROC) of CC16 for ARDS diagnosis reached an AUC of 0.80 (95% CI: 0.76, 0.83). In conclusion, this study provides a ranking system for pulmonary-originated epithelial biomarkers according to their association with distinguishing at-risk patients and predicting mortality. In addition, the study provides evidence for the advantage of biomarkers over traditional diagnostic criteria. The performance of biomarkers may help to clinically improve the ARDS diagnosis and mortality prediction.

Effect of Club cell secretory proteins on the association of tobacco smoke and PAH co-exposure with lung function decline: A longitudinal observation of Chinese coke oven workers

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAH) and tobacco smoke is associated with epithelial damage and reduced lung function. Club cell secretory protein (CC16) is a known biomarker for lung epithelial cells. However, the potential relationships between PAH and tobacco smoke exposure, CC16 levels, and reduced lung function remain unclear.

OBJECTIVES

This longitudinal study aimed to explore the potential role of CC16 in the association of tobacco smoke and PAH co-exposure with lung function.

METHODS

We enrolled 313 workers from a coking plant in China in 2014 and followed them up in 2019. The concentrations of PAH and nicotine metabolites in urine were determined using high-performance liquid chromatography (HPLC) with a fluorescence detector and HPLC-tandem mass spectrometry, respectively. The plasma CC16 concentration was determined using an enzyme-linked immunosorbent assay.

RESULTS

An analysis of the generalized estimating equation showed that each 1-unit increase in log-transformation of the last tertile of trans-3'-hydroxycotinine (3HC) was associated with a 3.30 ng/ml decrease in CC16. Restricted cubic spline analysis revealed a significant nonlinear dose-effect association between cotinine (COT) and CC16 (P_nonlinear = 0.018). In the low- CC16 subgroup, we found a significant association between total nicotine metabolites and forced vital capacity (FVC%) (β: 1.45, 95% CI: 2.87, -0.03), and the associations of nicotine (NIC), COT, and 3HC with FVC% were all of marginal significance. High levels of total hydroxyl polycyclic aromatic hydrocarbons (ΣOH-PAH) and NIC in the urine had an interactive effect on the decline of CC16 (P < 0.05). Cross-lagged panel analysis indicated that the decrease in CC16 preceded the decrease in FVC%. CC16 mediated the association between elevated nicotine metabolites and decreased FVC% in the low- CC16 subgroup.

CONCLUSIONS

CC16 plays an essential role in the association of PAH and tobacco smoke exposure with reduced lung function. Coke oven workers with low plasma CC16 levels are more likely to experience decreased lung function after tobacco smoke exposure.

Noninvasive integrative approach applied to children in the context of recent air pollution exposure demonstrates association between fractional exhaled nitric oxide (FeNO) and urinary CC16

Exposure to the air pollutant particulate matter (PM) is associated with increased risks of respiratory diseases and enhancement of airway inflammation in children. In the context of large scale air pollution studies, it can be challenging to measure fractional exhaled nitric oxide (FeNO) as indicator of lung inflammation. Urinary CC16 (U-CC16) is a potential biomarker of increased lung permeability and toxicity, increasing following short-term PM_2.5 exposure. The single nucleotide polymorphism (SNP) CC16 G38A (rs3741240) affects CC16 levels and respiratory health. Our study aimed at assessing the use of U-CC16 (incl. CC16 G38A from saliva) as potential alternative for FeNO by investigating their mutual correlation in children exposed to PM. Samples from a small-scale study conducted in 42 children from urban (n = 19) and rural (n = 23) schools examined at two time points, were analysed. When considering recent (lag1) low level exposure to PM_2.5 as air pollution measurement, we found that U-CC16 was positively associated with FeNO (β = 0.23; 95% CI [-0.01; 0.47]; p = 0.06) in an adjusted analysis using a linear mixed effects model. Further, we observed a positive association between PM_2.5 and FeNO (β = 0.56; 95% CI [0.02; 1.09]; p = 0.04) and higher FeNO in urban school children as compared to rural school children (β = 0.72; 95% CI [0.12; 1.31]; p = 0.02). Although more investigations are needed, our results suggest that inflammatory responses evidenced by increased FeNO are accompanied by potential increased lung epithelium permeability and injury, evidenced by increased U-CC16. In future large scale studies, where FeNO measurement is less feasible, the integrated analysis of U-CC16 and CC16 G38A, using noninvasive samples, might be a suitable alternative to assess the impact of air pollution exposure on the respiratory health of children, which is critical for policy development at population level.

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.

Cross-sectional Study of Workers Employed at a Copper Smelter-Effects of Long-term Exposures to Copper on Lung Function and Chronic Inflammation

OBJECTIVE

The aim of the study was to assess the effect of exposure to copper-containing dust on lung function and inflammatory endpoints among workers of a German copper plant, effects rarely studied before.

METHODS

One hundred four copper-exposed smelter workers and 70 referent workers from the precious metal and lead facilities were included, with different metal exposures in both groups due to the different process materials. Body plethysmography, exhaled nitric oxide (FeNO) measurements, and blood sampling were conducted in all workers. Smoking status and the use of respiratory protective equipment were considered. In a subgroup of 40 nonsmoking volunteers (28 copper-exposed and 12 referents), sputum biomarkers were assessed.

RESULTS

Median lung function values of both copper-exposed and the referent groups were within reference ranges of "healthy" individuals, and statistical differences between the groups were mostly not evident. Similarly, differences in blood and sputum biomarkers were too small to be biologically relevant.

CONCLUSION

The results suggest the absence of the detectable effects of copper-containing dust exposure on lung function or chronic inflammation within the investigated cohort.

Club cell secretory protein and lung function in children with cystic fibrosis

BACKGROUND

Club cell secretory protein (CC16) exerts anti-inflammatory functions in lung disease. We sought to determine the relation of serum CC16 deficits and genetic variants that control serum CC16 to lung function among children with cystic fibrosis (CF).

METHODS

We used longitudinal data from CF children (EPIC Study) with no positive cultures for Pseudomonas aeruginosa prior to enrollment. Circulating levels of CC16 and an inflammatory score (generated from CRP, SAA, calprotectin, G-CSF) were compared between participants with the lowest and highest FEV1 levels in adolescence (LLF and HLF groups, respectively; N = 130-per-group). Single nucleotide variants (SNVs) in the SCGB1A1, EHF-APIP loci were tested for association with circulating CC16 and with decline of FEV1 and FEV1/FVC% predicted levels between ages 7-16 using mixed models.

RESULTS

Compared with the HLF group, the LLF group had lower levels of CC16 (geometric means: 8.2 vs 6.5 ng/ml, respectively; p = 0.0002) and higher levels of the normalized inflammatory score (-0.21 vs 0.21, p = 0.0007). Participants in the lowest CC16 and highest inflammation tertile had the highest odds for having LLF (p<0.0001 for comparison with participants in the highest CC16 and lowest inflammation tertile). Among seven SNVs associated with circulating CC16, the top SNV rs3741240 was associated with decline of FEV1/FVC and, marginally, FEV1 (p = 0.003 and 0.025, respectively; N = 611 participants, 20,801 lung function observations).

CONCLUSIONS

Serum CC16 deficits are strongly associated with severity of CF lung disease and their effects are additive with systemic inflammation. The rs3741240 A allele is associated with low circulating CC16 and, possibly, accelerated lung function decline in CF.

Club cell protein (CC)16 as potential lung injury marker in a porcine 72 h polytrauma model

BACKGROUND

Polytrauma and respiratory tract damage after thoracic trauma cause about 25% of mortality among severely injured patients. Thoracic trauma can lead to the development of severe lung complications such as acute respiratory distress syndrome, and is, therefore, of great interest for monitoring in intensive care units (ICU). In recent years, club cell protein (CC)16 with its antioxidant properties has proven to be a potential outcome-related marker. In this study, we evaluated whether CC16 constitutes as a marker of lung damage in a porcine polytrauma model.

METHODS

In a 72 h ICU polytrauma pig model (thoracic trauma, tibial fracture, hemorrhagic shock, liver laceration), blood plasma samples (0, 3, 9, 24, 48, 72 h), BAL samples (72 h) and lung tissue (72 h) were collected. The trauma group (PT) was compared to a sham group. CC16 as a possible biomarker for lung injury in this model, and IL-8 concentrations as known indicator for ongoing inflammation during trauma were determined by ELISA. Histological analysis of ZO-1 and determination of total protein content were used to show barrier disruption and edema formation in lung tissue from the trauma group.

RESULTS

Systemic CC16 levels were significantly increased early after polytrauma compared vs. sham. After 72 h, CC16 concentration was significantly increased in lung tissue as well as in BAL in PT vs. sham. Similarly, IL-8 and total protein content in BAL were significantly increased in PT vs. sham. Evaluation of ZO-1 staining showed significantly lower signal intensity for polytrauma.

CONCLUSION

The data confirm for the first time in a larger animal polytrauma model that lung damage was indicated by systemic and/or local CC16 response. Thus, early plasma and late BAL CC16 levels might be suitable to be used as markers of lung injury in this polytrauma model.

Human airway organoids and microplastic fibers: A new exposure model for emerging contaminants

Three-dimensional (3D) structured organoids are the most advanced in vitro models for studying human health effects, but their application to evaluate the biological effects associated with microplastic exposure was neglected until now. Fibers from synthetic clothes and fabrics are a major source of airborne microplastics, and their release from dryer machines is poorly understood. We quantified and characterized the microplastic fibers (MPFs) released in the exhaust filter of a household dryer and tested their effects on airway organoids (1, 10, and 50 µg mL^-1) by optical microscopy, scanning electron microscopy (SEM), confocal microscopy and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). While the presence of MPFs did not inhibit organoid growth, we observed a significant reduction of SCGB1A1 gene expression related to club cell functionality and a polarized cell growth along the fibers. The MPFs did not cause relevant inflammation or oxidative stress but were coated with a cellular layer, resulting in the inclusion of fibers in the organoid. This effect could have long-term implications regarding lung epithelial cells undergoing repair. This exposure study using human airway organoids proved suitability of the model for studying the effects of airborne microplastic contamination on humans and could form the basis for further research regarding the toxicological assessment of emerging contaminants such as micro- or nanoplastics.

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.

What should be tested in patients with suspected mold exposure? Usefulness of serological markers for the diagnosis

The associations of mold exposure, IgE-mediated sensitization, inflammatory markers, and respiratory symptoms were analyzed in 46 exposed and 23 non-exposed individuals. Both exposure and clinical symptoms were assessed by questionnaire. Specific (s)IgE to mold mixture (mx1) was significantly higher and found more frequently in exposed (41%) than non-exposed individuals (17%), which was not observed for sIgG to mold mix (Gmx6). Notably, exposed asthmatics were more frequently sensitized to molds (55%) compared to exposed non-asthmatics (18%). In addition, the serum concentrations of club cell protein (CC16) were significantly lower in exposed subjects, especially in asthmatics. Positive associations were observed among mold sensitization, asthma, and mold exposure, but not in subjects with predominantly environmental sensitizations without mold sensitization. Thus, sIgE to mx1 but not sIgG to Gmx6 is a useful diagnostic marker to verify mold-associated respiratory symptoms.

Associations between pre- and postnatal exposure to air pollution and lung health in children and assessment of CC16 as a potential mediator

BACKGROUND

Early life exposure to air pollution can affect lung health. Previous studies have not assessed the implications of both pre- and postnatal exposure to air pollutants on lung function at repeated ages during childhood. In addition, there is the need to identify potential mediators of such effect.

OBJECTIVES

To longitudinally assess the association between pre- and postnatal air pollution exposure and lung function during childhood. We also aimed to explore the role of Club cell secretory protein (CC16) as a potential mediator in this association.

METHODOLOGY

We included 487 mother-child pairs from the INMA (INfancia y Medio Ambiente) Sabadell birth cohort, recruited between 2004 and 2006. Air pollution exposure was estimated for pregnancy, pre-school age, and school-age using temporally adjusted land use regression (LUR) modelling. Lung function was measured at ages 4, 7, 9 and 11 by spirometry. At age 4, serum CC16 levels were determined in 287 children. Multivariable linear regression models and linear mixed modelling were applied, while considering potential confounders.

RESULTS

Prenatal exposure to Particulate Matter (PM)₁₀ and PM_coarse had the most consistent associations with reduced lung function in cross-sectional models. Associations with postnatal exposure were less consistent. Increasing CC16 levels at 4 years were associated with an increase in FEF_25-75 (β = 120.4 mL, 95% CI: 6.30, 234.5) from 4 to 11 years of age. No statistically significant associations were found between pre- or postnatal air pollution and CC16 at age 4.

CONCLUSION

Increasing levels of air pollution exposure, particularly prenatal PM₁₀ and PM_coarse exposure, were associated with a reduction in lung function. We were not able to confirm our hypothesis on the mediation role of CC16 in this association, however our results encourage further exploration of this possibility in future studies.

Lung developmental is altered after inhalation exposure to various concentrations of calcium arsenate

Exposure to dust from active and abandoned mining operations may be a very significant health hazard, especially to sensitive populations. We have previously reported that inhalation of real-world mine tailing dusts during lung development can alter lung function and structure in adult male mice. These real-world dusts contain a mixture of metal(loid)s, including arsenic. To determine whether arsenic in inhaled dust plays a role in altering lung development, we exposed C57Bl/6 mice to a background dust (0 arsenic) or to the background dust containing either 3% or 10% by mass, calcium arsenate. Total level of exposure was kept at 100 μg/m3. Calcium arsenate was selected since arsenate is the predominant species found in mine tailings. We found that inhalation exposure during in utero and postnatal lung development led to significant increases in pulmonary baseline resistance, airway hyper-reactivity, and airway collagen and smooth muscle expression in male C57Bl/6 mice. Responses were dependent on the level of calcium arsenate in the simulated dust. These changes were not associated with increased expression of TGF-β1, a marker of epithelial to mesenchymal transition. However, responses were correlated with decreases in the expression of club cell protein 16 (CC16). Dose-dependent decreases in CC16 expression and increases in collagen around airways was seen for animals exposed in utero only (GD), animals exposed postnatally only (PN) and animals continuously exposed throughout development (GDPN). These data suggest that arsenic inhalation during lung development can decrease CC16 expression leading to functional and structural alterations in the adult lung.

Exercise duration modulates upper and lower respiratory fluid cellularity, antiviral activity, and lung gene expression

Exercise has substantial health benefits, but the effects of exercise on immune status and susceptibility to respiratory infections are less clear. Furthermore, there is limited research examining the effects of prolonged exercise on local respiratory immunity and antiviral activity. To assess the upper respiratory tract in response to exercise, we collected nasal lavage fluid (NALF) from human subjects (1) at rest, (2) after 45 min of moderate-intensity exercise, and (3) after 180 min of moderate-intensity exercise. To assess immune responses of the lower respiratory tract, we utilized a murine model to examine the effect of exercise duration on bronchoalveolar lavage (BAL) fluid immune cell content and lung gene expression. NALF cell counts did not change after 45 min of exercise, whereas 180 min significantly increased total cells and leukocytes in NALF. Importantly, fold change in NALF leukocytes correlated with the post-exercise fatigue rating in the 180-min exercise condition. The acellular portion of NALF contained strong antiviral activity against Influenza A in both resting and exercise paradigms. In mice undergoing moderate-intensity exercise, BAL total cells and neutrophils decreased in response to 45 or 90 min of exercise. In lung lobes, increased expression of heat shock proteins suggested that cellular stress occurred in response to exercise. However, a broad upregulation of inflammatory genes was not observed, even at 180 min of exercise. This work demonstrates that exercise duration differentially alters the cellularity of respiratory tract fluids, antiviral activity, and gene expression. These changes in local mucosal immunity may influence resistance to respiratory viruses, including influenza or possibly other pathogens in which nasal mucosa plays a protective role, such as rhinovirus or SARS-CoV-2.

Respiratory Health and Inflammatory Markers-Exposure to Cobalt in the Swedish Hard Metal Industry

OBJECTIVE

To study the relationship between inhalable dust and cobalt, and respiratory symptoms, lung function, exhaled nitric oxide in expired air, and CC16 in the Swedish hard metal industry.

METHODS

Personal sampling of inhalable dust and cobalt, and medical examination including blood sampling was performed for 72 workers. Exposure-response relationships were determined using logistic, linear, and mixed-model analysis.

RESULTS

The average inhalable dust and cobalt concentrations were 0.079 and 0.0017 mg/m, respectively. Statistically significant increased serum levels of CC16 were determined when the high and low cumulative exposures for cobalt were compared. Nonsignificant exposure-response relationships were observed between cross-shift inhalable dust or cobalt exposures and asthma, nose dripping, and bronchitis.

CONCLUSIONS

Our findings suggest an exposure-response relationship between inhalable cumulative cobalt exposure and CC16 levels in blood, which may reflect an injury or a reparation process in the lungs.

Inflammatory and coagulatory markers and exposure to different size fractions of particle mass, number and surface area air concentrations in the Swedish hard metal industry, in particular to cobalt

PURPOSE

To study the relationship between inhalation of airborne particles and cobalt in the Swedish hard metal industry and markers of inflammation and coagulation in blood.

METHODS

Personal sampling of inhalable cobalt and dust were performed for subjects in two Swedish hard metal plants. Stationary measurements were used to study concentrations of inhalable, respirable, and total dust and cobalt, PM₁₀ and PM_2.5, the particle surface area and the particle number concentrations. The inflammatory markers CC16, TNF, IL-6, IL-8, IL-10, SAA and CRP, and the coagulatory markers FVIII, vWF, fibrinogen, PAI-1 and D-dimer were measured. A complete sampling was performed on the second or third day of a working week following a work-free weekend, and additional sampling was taken on the fourth or fifth day. The mixed model analysis was used, including covariates.

RESULTS

The average air concentrations of inhalable dust and cobalt were 0.11 mg/m³ and 0.003 mg/m³, respectively. For some mass-based exposure measures of cobalt and total dust, statistically significant increased levels of FVIII, vWF and CC16 were found.

CONCLUSIONS

The observed relationships between particle exposure and coagulatory biomarkers may indicate an increased risk of cardiovascular disease.

Inflammation biomarkers associated with arsenic exposure by drinking water and respiratory outcomes in indigenous children from three Yaqui villages in southern Sonora, México

Environmental arsenic exposure in adults and children has been associated with a reduction in the expression of club cell secretory protein (CC16) and an increase in the expression of matrix metalloproteinase-9 (MMP-9), both biomarkers of lung inflammation and negative respiratory outcomes. The objectives of this study were to determine if the levels of serum CC16 and MMP-9 and subsequent respiratory infections in children are associated with the ingestion of arsenic by drinking water. This cross-sectional study included 216 children from three Yaqui villages, Potam, Vicam, and Cocorit, with levels of arsenic in their ground water of 70.01 ± 21.85, 23.3 ± 9.99, and 11.8 ± 4.42 μg/L respectively. Total arsenic in water and urine samples was determined by inductively coupled plasma/optical emission spectrometry. Serum was analyzed for CC16 and MMP-9 using ELISA. The children had an average urinary arsenic of 79.39 μg/L and 46.8 % had levels above of the national concern value of 50 μg/L. Increased arsenic concentrations in drinking water and average daily arsenic intake by water were associated with decreased serum CC16 levels (β = - 0.12, 95% CI - 0.20, - 0.04 and β = - 0.10, 95% CI - 0.18, - 0.03), and increased serum MMP-9 levels (β = 0.35, 95% CI 0.22, 0.48 and β = 0.29, 95% CI 0.18, 0.40) at significant levels (P < 0.05). However, no association was found between levels of these serum biomarkers and urinary arsenic concentrations. In these children, reduced serum CC16 levels were significantly associated with increased risk of respiratory infections (OR = 0.34, 95% CI 0.13, 0.90). In conclusion, altered levels of serum CC16 and MMP-9 in the children may be due to the toxic effects of arsenic exposure through drinking water.

Mechanisms and biomarkers of airway epithelial cell damage in asthma: A review

Bronchial asthma is a heterogeneous disease with complex pathological mechanisms representing different phenotypes, including severe asthma. The airway epithelium is a major site of complex pathological changes in severe asthma due, in part, to activation of inflammatory and immune mechanisms in response to noxious agents. Current imaging procedures are unable to accurately measure epithelial and airway remodeling. Damage of airway epithelial cells occurs is linked to specific phenotypes and endotypes which provides an opportunity for the identification of biomarkers reflecting epithelial, and airway, remodeling. Identification of patients with more severe epithelial disruption using biomarkers may also provide personalised therapeutic opportunities and/or markers of successful therapeutic intervention. Here, we review the evidence for ongoing epithelial cell dysregulation in the pathogenesis of asthma, the sentinel role of the airway epithelium and how understanding these molecular mechanisms provides the basis for the identification of candidate biomarkers for asthma prediction, prevention, diagnosis, treatment and monitoring.

CC16 Binding to α4β1 Integrin Protects against Mycoplasma pneumoniae Infection

Rationale CC16 (club cell secretory protein) is a pneumoprotein produced predominantly by pulmonary club cells. Circulating CC16 is associated with protection from the inception and progression of the two most common obstructive lung diseases (asthma and chronic obstructive pulmonary disease). Objectives Although exact mechanisms remain elusive, studies consistently suggest a causal role of CC16 in mediating antiinflammatory and antioxidant functions in the lung. We sought to determine any novel receptor systems that could participate in CC16's role in obstructive lung diseases. Methods Protein alignment of CC16 across species led to the discovery of a highly conserved sequence of amino acids, leucine-valine-aspartic acid (LVD), a known integrin-binding motif. Recombinant CC16 was generated with and without the putative integrin-binding site. A Mycoplasma pneumoniae mouse model and a fluorescent cellular adhesion assay were used to determine the impact of the LVD site regarding CC16 function during live infection and on cellular adhesion during inflammatory conditions. Measurements and Main Results CC16 bound to integrin α₄β₁), also known as the adhesion molecule VLA-4 (very late antigen 4), dependent on the presence of the LVD integrin-binding motif. During infection, recombinant CC16 rescued lung function parameters both when administered to the lung and intravenously but only when the LVD integrin-binding site was intact; likewise, neutrophil recruitment during infection and leukocyte adhesion were both impacted by the loss of the LVD site. Conclusions We discovered a novel receptor for CC16, VLA-4, which has important mechanistic implications for the role of CC16 in circulation as well as in the lung compartment.

Club cell protein 16 as a biomarker for early detection of silicosis

Background & objectives

Clinically silicosis is diagnosed by chest X-ray showing specific opacities along with history of silica dust exposure. Diagnosis is invariably made at an advanced or end stage when it is irreversible. Moreover, silicosis patients are susceptible to develop tuberculosis. Therefore, a suitable biomarker for early detection of silicosis is needed. This study evaluated the suitability of club cell protein (CC16) as a biomarker for early detection of silicosis.

Methods

This pilot study included 121 individuals from X-ray-confirmed/advanced silicosis, moderate silica dust-exposed workers and healthy controls from western India. CC16 levels were quantified in serum samples through ELISA. Sensitivity and specificity of CC16 values at different cut-off points were calculated in both non-smokers and smokers.

Results

Serum CC16 level was significantly (P <0.01) decreased in X-ray confirmed advanced silicosis patients (4.7±3.07 ng/ml) followed by moderately exposed workers (10.2±1.77 ng/ml) as compared to healthy non-exposed individuals (16.7±3.81 ng/ml). Tobacco smoking also caused a significant decrease of serum CC16 concentration in both healthy (10.2±1.12 ng/ml) and advanced silicosis workers (2.6±2.28 ng/ml) compared to non-smokers. Sensitivity and specificity of CC16 values were also found to be ≥83 per cent for screening all categories of individuals.

Interpretation & conclusions

Because of high sensitivity and specificity, serum CC16 could be used as predictive biomarker for suspicion and early detection of silicosis, which would help in reducing/delaying premature deaths caused by silicosis. It would also control silicotuberculosis additionally.

An experimental exposure study revealing composite airway effects of physical exercise in a subzero environment

Exposure to a cold climate is associated with an increased morbidity and mortality, but the specific mechanisms are largely unknown. People with cardiopulmonary disease and winter endurance athletes are particularly vulnerable. This study aimed to map multiple domains of airway responses to exercise in subzero temperature in healthy individuals.

Thirty-one healthy subjects underwent whole-body exposures for 50 minutes on two occasions in an environmental chamber with intermittent moderate-intensity exercise in +10 °C and -10 °C. Lung function, plasma/urine CC16 , and symptoms were investigated before and after exposures.

Compared to baseline, exercise in -10 °C decreased FEV₁ (p=0.002), FEV₁/FVC (p<0.001), and increased R20Hz (p=0.016), with no differences between exposures. Reactance increased after +10 °C (p=0.005), which differed (p=0.042) from a blunted response after exercise in -10 °C. Plasma CC16 increased significantly within exposures, without differences between exposures. Exercise in -10 °C elicited more intense symptoms from the upper airways, compared to +10 °C. Symptoms from the lower airways were few and mild. 

Short-duration moderate-intensity exercise in -10 °C induces mild symptoms from the lower airways, no lung function decrements or enhanced leakage of biomarkers of airway epithelial injury, and no peripheral bronchodilatation, compared to exercise in +10 °C. 

Small Airways Disease, Biomarkers and COPD: Where are We?

The response to treatment and progression of Chronic Obstructive Pulmonary Disease (COPD) varies significantly. Small airways disease (SAD) is being increasingly recognized as a key pathological feature of COPD. Studies have brought forward pathological evidence of small airway damage preceding the development of emphysema and the detection of obstruction using traditional spirometry. In recent years, there has been a renewed interest in the early detection of SAD and this has brought along an increased demand for physiological tests able to identify and quantify SAD. Early detection of SAD allows early targeted therapy and this suggests the potential for altering the course of disease. The aim of this article is to review the evidence available on the physiological testing of small airways. The first half will focus on the role of lung function tests such as maximum mid-expiratory flow, impulse oscillometry and lung clearance index in detecting and quantifying SAD. The role of Computed Tomography (CT) as a radiological biomarker will be discussed as well as the potential of recent CT analysis software to differentiate normal aging of the lungs to pathology. The evidence behind SAD biomarkers sourced from blood as well as biomarkers sourced from sputum and broncho-alveolar lavage (BAL) will be reviewed. This paper focuses on CC-16, sRAGE, PAI-1, MMP-9 and MMP-12.

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.

Extrapulmonary Surfactant Therapy: Review of Available Data and Research/Development Issues

Since the discovery of surfactant, a large amount of knowledge has been accumulated about its biology and pharmacology. Surfactant is the cornerstone of neonatal respiratory critical care, but its proteins and phospholipids are produced in various tissues and organs, with possible roles only partially similar to that played in the alveoli. As surfactant research is focused mainly on its respiratory applications, knowledge about the possible role of surfactant in extrapulmonary disorders has never been summarized. Here we aim to comprehensively review the data about surfactant biology and pharmacology in organs other than the lung, especially focusing in the more promising surfactant extrapulmonary roles. We also review any preclinical or clinical data available about the therapeutic use of surfactant in these contexts. We offer a summary of knowledge and research/development milestones, as possible useful guidance for researchers of multidisciplinary background.

Glycoprotein biomarkers and analysis in chronic obstructive pulmonary disease and lung cancer with special focus on serum immunoglobulin G

Chronic obstructive pulmonary disease (COPD) and lung cancer are two major diseases of the lung with high rate of mortality, mostly among tobacco smokers. The glycosylation patterns of various plasma proteins show significant changes in COPD and subsequent hypoxia, inflammation and lung cancer, providing promising opportunities for screening aberrant glycan structures contribute to early detection of both diseases. Glycoproteins associated with COPD and lung cancer consist of highly sialylated N-glycans, which play an important role in inflammation whereby hypoxia leads to accumulation of sialyl Lewis A and X glycans. Although COPD is an inflammatory disease, it is an independent risk factor for lung cancer. Marked decrease in galactosylation of plasma immunoglobulin G (IgG) together with increased presence of sialic acids and more complex highly branched N-glycan structures are characteristic for COPD and lung cancer. Numerous glycan biomarkers have been discovered, and analysis of glycovariants associated with COPD and lung cancer has been carried out. In this paper we review fundamental glycosylation changes in COPD and lung cancer glycoproteins, focusing on IgG to provide an opportunity to distinguish between the two diseases at the glycoprotein level with diagnostic value.

Plasma CC16 mediates the associations between urinary metals and fractional exhaled nitric oxide: A cross-sectional study

Exposure to environmental metals has been reported to be associated with airway inflammation. Fractional exhaled nitric oxide (FeNO) is an important inflammatory biomarker of the airway. However, the associations between metal exposures and FeNO change and the underlying mechanisms remain unclear. To investigate the associations between urinary metals and FeNO, and the potential role of Club cell secretory protein (CC16), a lung epithelial biomarker, in these associations. We conducted a cross-sectional study from the Wuhan-Zhuhai cohort and measured eight urinary metals, plasma CC16 and FeNO among 3067 subjects by using inductively coupled plasma-mass spectrometry, enzyme-linked immunosorbent assay kit and Nano Coulomb Nitric Oxide Analyzer, respectively. Mixed linear models were used to quantify dose-relationships between urinary metals and FeNO, as well as urinary metals and plasma CC16. The potential role of plasma CC16 in the associations between urinary metals and FeNO was estimated using mediationanalyses. After adjusting for covariates, one percent increase in urinary vanadium, nickel or antimony was associated with a respective 6.60% (95% CI: 3.52%, 9.68%), 2.18% (0.45%, 3.91%), 4.87% (1.47%, 8.27%) increase in FeNO level. The adverse associations were much stronger among participants with low concentration of plasma CC16 than those with high CC16 level. Moreover, plasma CC16 decreased monotonically with increasing quartiles of urinary vanadium, nickel or antimony. Mediation analyses found that CC16 mediated the associations between urinary metals and FeNO by 5.64%, 39.06% and 25.18% for vanadium, nickel and antimony respectively. CC16 plays an important role in airway inflammation. General population with lower plasma CC16 concentration is more likely to suffer from airway inflammation when exposed to high levels of vanadium, nickel or antimony.

The Club Cell Marker SCGB1A1 Downstream of FOXA2 is Reduced in Asthma

Human SCGB1A1 protein has been shown to be significantly reduced in BAL, sputum, and serum from humans with asthma as compared with healthy individuals. However, the mechanism of this reduction and its functional impact have not been entirely elucidated. By mining online datasets, we found that the mRNA of SCGB1A1 was significantly repressed in brushed human airway epithelial cells from individuals with asthma, and this repression appeared to be associated with reduced expression of FOXA2. Consistently, both Scgb1A1 and FoxA2 were downregulated in an ovalbumin-induced mouse model of asthma. Furthermore, compared with wild-type mice, Scgb1a1 knockout mice had increased airway hyperreactivity and inflammation when they were exposed to ovalbumin, confirming the antiinflammatory role of Scgb1a1 in protection against asthma phenotypes. To search for potential asthma-related stimuli of SCGB1A1 repression, we tested T-helper cell type 2 cytokines. Both IL-4 and IL-13 repressed epithelial expression of SCGB1A1 and FOXA2. Importantly, infection of epithelial cells with human rhinovirus similarly reduced expression of these two genes, which suggests that FOXA2 may be the common regulator of SCGB1A1. To establish the causal role of reduced FOXA2 in SCGB1A1 repression, we demonstrated that FOXA2 was required for SCGB1A1 expression at baseline. FOXA2 overexpression was sufficient to drive promoter activity and expression of SCGB1A1 and was also able to restore the repressed SCGB1A1 expression in IL-13-treated or rhinovirus-infected cells. Taken together, these findings suggest that low levels of epithelial SCGB1A1 in asthma are caused by reduced FOXA2 expression.

Respiratory health and inflammatory markers - Exposure to respirable dust and quartz and chemical binders in Swedish iron foundries

Purpose

To study the relationship between respirable dust, quartz and chemical binders in Swedish iron foundries and respiratory symptoms, lung function (as forced expiratory volume FEV₁ and vital capacity FVC), fraction of exhaled nitric oxide (FENO) and levels of club cell secretory protein 16 (CC16) and CRP.

Methods

Personal sampling of respirable dust and quartz was performed for 85 subjects in three Swedish iron foundries. Full shift sampling and examination were performed on the second or third day of a working week after a work free weekend, with additional sampling on the fourth or fifth day. Logistic, linear and mixed model analyses were performed including, gender, age, smoking, infections, sampling day, body mass index (BMI) and chemical binders as covariates.

Results

The adjusted average respirable quartz and dust concentrations were 0.038 and 0.66 mg/m³, respectively. Statistically significant increases in levels of CC16 were associated with exposure to chemical binders (p = 0.05; p = 0.01) in the regression analysis of quartz and respirable dust, respectively. Non-significant exposure-responses were identified for cumulative quartz and the symptoms asthma and breathlessness. For cumulative chemical years, non-significant exposure–response were observed for all but two symptoms. FENO also exhibited a non significant exposure-response for both quartz and respirable dust. No exposure-response was determined for FEV₁ or FVC, CRP and respirable dust and quartz.

Conclusions

Our findings suggest that early markers of pulmonary effect, such as increased levels of CC16 and FENO, are more strongly associated with chemical binder exposure than respirable quartz and dust in foundry environments.

CC16 Levels into Adult Life Are Associated with Nitrogen Dioxide Exposure at Birth

Rationale: Lung function and growth are adversely associated with nitrogen dioxide (NO2) exposure. Lower levels of circulating club cell secretory protein (CC16) in childhood are also associated with subsequent decreased lung function. NO2 exposure may induce epithelial damage in lungs and alter club cell proliferation and morphology.Objectives: To determine if increased ambient NO2 levels at participants' home addresses in early life were associated with decreased levels of CC16 from age 6 to 32 years.Methods: Participants were enrolled at birth in the Tucson Children's Respiratory Study and had circulating CC16 measured at least once between age 6 and 32. Linear mixed models were used to determine the association between estimated ambient NO2 exposure at participants' home address at birth or age 6 with CC16 levels from age 6 to 32.Measurements and Main Results: NO2 exposures at birth or age 6 were available for 777 children with one or more CC16 measurement. We found a negative association between NO2 exposure and CC16 levels, with a 4.7% (95% confidence interval, -8.6 to -0.7) decrease in CC16 levels from age 6 to 32 per interquartile range increase in NO2 exposure (6.0 ppb) at the participants' birth address. We observed modification by race (p interaction = 0.04), with stronger associations among participants with at least one black parent (-29.6% [95% confidence interval, -42.9% to -13.2%] per interquartile range). NO2 at participant's age 6 address was not significantly associated with CC16 levels (-1.9%; 95% confidence interval, -6.3 to 2.6).Conclusions: Higher exposure to NO2 at birth is associated with persistently low levels of CC16 from 6 to 32 years.

Allele-specific expression identified rs2509956 as a novel long-distance cis-regulatory SNP for SCGB1A1, an important gene for multiple pulmonary diseases

SCGB1A1 (secretoglobin family 1A member 1) is an important protein for multiple pulmonary diseases, especially asthma, chronic obstructive pulmonary disease, and lung cancer. One single-nucleotide polymorphism (SNP) at 5'-untranslated region of SCGB1A1, rs3741240, has been suggested to be associated with reduced protein expression and further asthma susceptibility. However, it was still unclear whether there were other cis-regulatory elements for SCGB1A1 that might further contribute to pulmonary diseases. Allele-specific expression (ASE) is a novel approach to identify the functional region in human genome. In the present study, we measured ASE on rs3741240 in lung tissues and observed a consistent excess of G allele over A (P < 10^-6), which indicated that this SNP or the one(s) in linkage disequilibrium (LD) could regulate SCGB1A1 expression. By analyzing 1000 Genomes Project data for Chinese, one SNP locating ~10.2 kb away and downstream of SCGB1A1, rs2509956, was identified to be in strong LD with rs3741240. Reporter gene assay confirmed that both SNPs could regulate gene expression in the lung cell. By chromosome conformation capture, it was verified that the region surrounding rs2509956 could interact with SCGB1A1 promoter region and act as an enhancer. Through chromatin immunoprecipitation and overexpression assay, the related transcription factor RELA (RELA proto-oncogene, NF-kB subunit) was recognized to bind the region spanning rs2509956. Our work identified a novel long-distance cis-regulatory SNP for SCGB1A1, which might contribute to multiple pulmonary diseases.

A Microfabricated Sandwiching Assay for Nanoliter and High-Throughput Biomarker Screening

Cells secrete substances that are essential to the understanding of numerous immunological phenomena and are extensively used in clinical diagnoses. Countless techniques for screening of biomarker secretion in living cells have generated valuable information on cell function and physiology, but low volume and real-time analysis is a bottleneck for a range of approaches. Here, a simple, highly sensitive assay using a high-throughput micropillar and microwell array chip (MIMIC) platform is presented for monitoring of biomarkers secreted by cancer cells. The sensing element is a micropillar array that uses the enzyme-linked immunosorbent assay (ELISA) mechanism to detect captured biomolecules. When integrated with a microwell array where few cells are localized, interleukin 8 (IL-8) secretion can be monitored with nanoliter volume using multiple micropillar arrays. The trend of cell secretions measured using MIMICs matches the results from conventional ELISA well while it requires orders of magnitude less cells and volumes. Moreover, the proposed MIMIC is examined to be used as a drug screening platform by delivering drugs using micropillar arrays in combination with a microfluidic system and then detecting biomolecules from cells as exposed to drugs.

Fourth generation e-cigarette vaping induces transient lung inflammation and gas exchange disturbances: results from two randomized clinical trials

When heated by an electronic cigarette, propylene glycol and glycerol produce a nicotine-carrying-aerosol. This hygroscopic/hyperosmolar aerosol can deposit deep within the lung. Whether these deposits trigger local inflammation and disturb pulmonary gas exchanges is not known. The aim of this study was to assess the acute effects of high-wattage electronic cigarette vaping with or without nicotine on lung inflammation biomarkers, transcutaneous gas tensions, and pulmonary function tests in young and healthy tobacco smokers. Acute effects of vaping without nicotine on arterial blood gas tensions were also assessed in heavy smokers suspected of coronary artery disease. Using a single-blind within-subjects study design, 25 young tobacco smokers underwent three experimental sessions in random order: sham-vaping and vaping with and without nicotine at 60 W. Twenty heavy smokers were also exposed to sham-vaping (n = 10) or vaping without nicotine (n = 10) in an open-label, randomized parallel study. In the young tobacco smokers, compared with sham-vaping: 1) serum club cell protein-16 increased after vaping without nicotine (mean ± SE, −0.5 ± 0.2 vs. +1.1 ± 0.3 µg/l, P = 0.013) and vaping with nicotine (+1.2 ± 0.3 µg/l, P = 0.009); 2) transcutaneous oxygen tension decreased for 60 min after vaping without nicotine (nadir, −0.3 ± 1 vs. −15.3 ± 2.3 mmHg, P < 0.001) and for 80-min after vaping with nicotine (nadir, −19.6 ± 2.8 mmHg, P < 0.001). Compared with sham vaping, vaping without nicotine decreased arterial oxygen tension for 5 min in heavy-smoking patients (+5.4 ± 3.3 vs. −5.4 ± 1.9 mmHg, P = 0.012). Acute vaping of propylene glycol/glycerol aerosol at high wattage with or without nicotine induces airway epithelial injury and sustained decrement in transcutaneous oxygen tension in young tobacco smokers. Intense vaping conditions also transiently impair arterial oxygen tension in heavy smokers.

Club Cell Secretory Protein Deficiency Leads to Altered Lung Function

RATIONALE

CC16 (club cell secretory protein-16), a member of the secretoglobin family, is one of the most abundant proteins in normal airway secretions and has been described as a serum biomarker for obstructive lung diseases.

OBJECTIVES

To determine whether low CC16 is a marker for airway pathology or is implicated in the pathophysiology of progressive airway damage in these conditions.

METHODS

Using human data from the birth cohort of the Tucson Children's Respiratory Study, we examined the relation of circulating CC16 levels with pulmonary function and responses to bronchial methacholine challenge from childhood up to age 32 years. In wild-type and CC16-/- mice, we set out to comprehensively examine pulmonary physiology, inflammation, and remodeling in the naive airway.

MEASUREMENTS AND MAIN RESULTS

We observed that Tucson Children's Respiratory Study participants in the lowest tertile of serum CC16 had significant deficits in their lung function and enhanced airway hyperresponsiveness to methacholine challenge from 11 years throughout young adult life. Similarly, CC16-/- mice had significant deficits in lung function and enhanced airway hyperresponsiveness to methacholine as compared with wild-type mice, which were independent of inflammation and mucin production. As compared with wild-type mice, CC16-/- mice had significantly elevated gene expression of procollagen type I, procollagen type III, and α-smooth muscle actin, areas of pronounced collagen deposition and significantly enhanced smooth muscle thickness.

CONCLUSIONS

Our findings support clinical observations by providing evidence that lack of CC16 in the lung results in dramatically altered pulmonary function and structural alterations consistent with enhanced remodeling.

Pneumoproteins in Offshore Drill Floor Workers

The aim was to assess pneumoproteins and a certain biomarker of systemic inflammation in drill floor workers exposed to airborne contaminants generated during drilling offshore, taking into consideration serum biomarkers of smoking, such as nicotine (S-Nico) and cotinine. Blood samples of club cell protein 16 (CC-16), surfactant protein D (SP-D) and C-reactive protein (CRP) were collected before and after a 14-day work period from 65 drill floor workers and 65 referents. Air samples of oil mist, drilling mud components and elemental carbon were collected in person. The drill floor workers were exposed to a median air concentration of 0.18 mg/m³ of oil mist and 0.14 mg/m³ of airborne mud particles. There were no differences in the concentrations of CC-16 and SP-D across the 14-day work period and no difference between drill floor workers and referents at baseline after adjusting for differences in sampling time and smoking. CRP decreased across the work period. There was a strong association between the CC-16 concentrations and the time of sampling. Current smokers with S-Nico > detection limit (DL) had a statistically significantly lower CC-16 concentration, while smokers with S-Nico < DL had CC-16 concentrations similar to that of the non-smokers. Fourteen days of work offshore had no effect on serum pneumoprotein and CRP concentrations. However, the time of blood sampling was observed to have a strong effect on the measured concentrations of CC-16. The effect of current smoking on the CC-16 concentrations appears to be dependent on the S-Nico concentrations.

Decreased serum club cell secretory protein in asthma and chronic obstructive pulmonary disease overlap: a pilot study

Purpose

Improvement in the diagnosis of asthma and chronic obstructive pulmonary disease (COPD) overlap (ACO), and identification of biomarkers for phenotype recognition will encourage good patient care by providing optimal therapy. We investigated club cell secretory protein (CC-16), a protective and anti-inflammatory mediator, as a new candidate biomarker for diagnosing ACO.

Patients and methods

We performed a multicenter cohort study. A total of 107 patients were divided into three groups - asthma, COPD, and ACO - according to the Spanish guidelines algorithm, and enrolled into the study. Serum CC-16 levels were measured using commercial ELISA kits.

Results

Serum CC-16 levels were the lowest in patients with ACO. Low serum CC-16 levels were a significant marker for the ACO even after adjustment for age, sex, and smoking intensity. Serum CC-16 levels were positively correlated with forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), forced expiratory flow at 25%-75% of FVC, FEV₁/FVC, vital capacity, and diffusing capacity of the lung for carbon monoxide, and were negatively correlated with smoking amount (pack-years), bronchodilator response, fractional residual capacity, residual volume, and number of exacerbations per year. FEV₁ and serum CC-16 levels were significantly lower in patients with frequent exacerbations.

Conclusion

Serum CC-16 has the potential to be a biomarker for ACO diagnosis and also treat frequent exacerbations in patients with chronic inflammatory airway diseases.

Burnt sugarcane harvesting work: effects on pulmonary and systemic inflammatory markers

Objective: To evaluate the effects of burnt sugarcane harvesting on the plasmatic and urinary concentrations of the club cell secretory protein (CC16) and inflammatory systemic biomarkers in a group of sugarcane cutters. Methods: Seventy-eight sugar cane workers were evaluated. The plasmatic and urinary concentrations of CC16, a pulmonary damage marker and inflammatory systemic biomarkers were collected at three time points: before, three months after and six months after the onset of the burnt sugarcane harvesting period. All evaluations were performed at ∼7 am, before the daily work shift. In the three-month evaluation, a post-work shift assessment (acute effect) was also performed. Results: The age of the workers was 37.9 ± 11.0 years. The PM_2.5 concentrations were 27.0 (23.0-33.0) and 101.0 (31.0-139.5) µg/m³ in the pre harvest and harvest periods, respectively (p < .001). Burnt sugarcane harvesting was associated with a reduction, throughout the work during burnt sugarcane harvesting (subchronic effect), in plasmatic and urinary CC16 concentrations. Acutely, there was a decrease in plasmatic concentrations. There were acute and subchronic increases in inflammatory markers (neutrophils, monocytes) and muscle damage markers (CK and LDH) and a decrease in red blood cells. Conclusions: Harvesting of burnt sugarcane was associated with acute and subchronic reductions in the plasmatic and urinary concentrations of CC16 protein and changes in systemic inflammatory markers.

Club cell secretory protein (CC16) in gastric fluid at birth and subsequent lung disease in preterm infants

BACKGROUND

Club cell secretory protein (CC16) probably has a role in protecting the lung from inflammation.

AIM

To evaluate if low levels of CC16 in gastric fluid at birth, reflecting low levels of CC16 in the lung, would be associated with lung inflammation and respiratory morbidity.

METHODS

A study of 64 infants with mean gestational age 26.1 weeks. CC16 was analyzed in gastric fluid at birth. CC16, pro-inflammatory cytokines, and MMP-9 were analyzed in tracheal aspirate within 24 h from birth.

RESULTS

CC16 in gastric fluid increased with gestational age (P = 0.033). Lower concentrations of CC16 in gastric fluid at birth were associated with higher concentrations of IL-1β (P = 0.028), TNF-α (P = 0.034), and MMP-9 (P = 0.015) in tracheal aspirate. Infants who needed mechanical ventilation at 24 and 72 h of age had lower CC16 in gastric fluid than those not ventilated at these ages (P = 0.011 and P = 0.024, respectively). Lower CC16 in gastric fluid was associated with higher FiO₂ at 6 h (P = 0.009), higher PaCO₂ at 24 h (P = 0.03), more ventilator days (P = 0.012) and more days with supplemental oxygen (P = 0.03). Infants who had either died or were still treated with supplemental oxygen at 36 weeks postmenstrual age had lower CC16 in gastric fluid than infants with none of these outcomes (P = 0.049).

CONCLUSION

A low CC16 concentration in gastric fluid at birth was associated with increased inflammation in the trachea within the first 24 h of life and with more need for respiratory support in the neonatal period.

Airways exudation of plasma macromolecules: Innate defense, epithelial regeneration, and asthma

This review discusses in vivo airway aspects of plasma exudation in relation to current views on epithelial permeability and epithelial regeneration in health and disease. Microvascular-epithelial exudation of bulk plasma proteins characteristically occurs in asthmatic patients, being especially pronounced in those with severe and exacerbating asthma. Healthy human and guinea pig airways challenged by noninjurious histamine-leukotriene–type autacoids also respond through prompt mucosal exudation of nonsieved plasma macromolecules. Contrary to current beliefs, epithelial permeability in the opposite direction (ie, absorption of inhaled molecules) has not been increased in patients with asthma and allergic rhinitis or in acutely exuding healthy airways. A slightly increased subepithelial hydrostatic pressure produces such unidirectional outward perviousness to macromolecules. Lack of increased absorption permeability in asthmatic patients can further be reconciled with occurrence of epithelial shedding, leaving small patches of denuded basement membrane. Counteracting escalating barrier breaks, plasma exudation promptly covers the denuded patches. Here it creates and sustains a biologically active barrier involving a neutrophil-rich, fibrin-fibronectin net. Furthermore, in the plasma-derived milieu, all epithelial cell types bordering the denuded patch dedifferentiate and migrate from all sides to cover the denuded basement membrane. However, this speedy epithelial regeneration can come at a cost. Guinea pig in vivo studies demonstrate that patches of epithelial denudation regeneration are exudation hot spots evoking asthma-like features, including recruitment/activation of granulocytes, proliferation of fibrocytes/smooth muscle cells, and basement membrane thickening. In conclusion, nonsieved plasma macromolecules can operate on the intact airway mucosa as potent components of first-line innate immunity responses. Exuded plasma also takes center stage in epithelial regeneration. When exaggerated, epithelial regeneration can contribute to the inception and development of asthma.

Biomarkers of respiratory allergy in laboratory animal care workers: an observational study

OBJECTIVES

Laboratory animal allergy is a highly prevalent occupational disease among exposed workers. The aim of the study was to validate the biomarkers of airway inflammation in laboratory animal (LA) care workers.

METHODS

All of the participants in this observational study (63 LA care workers and 64 controls) were administered a clinical questionnaire, underwent spirometry and a skin prick or radioallergosorbent test for common and occupational aeroallergens, and the fraction of exhaled nitric oxide (FeNO₅₀), exhaled breath condensate hydrogen peroxide (EBC H₂O₂) and serum pneumoprotein levels were measured. Multivariate analysis (ANCOVA) was used to assess the interactions of the variables.

RESULTS

FeNO₅₀ levels correlated with exposure (p = 0.002), sensitisation (p = 0.000) and age (p = 0.001), but there was no interaction between exposure and sensitisation when age was considered in the model (p = 0.146). EBC-H₂O₂ levels were higher in the sensitised workers than in the sensitised controls [0.14 (0.08-0.29) µM vs 0.07 (0.05-0.12) µM; p < 0.05]. Serum surfactant protein A (SP-A) levels were unaffected by exposure, sensitisation or age, although higher levels were observed in symptomatic workers; however, SP-D levels were influenced by exposure (p = 0.024) and age (p = 0.022), and club cell 16 levels were influenced by sensitisation (p = 0.027) and age (p = 0.019).

CONCLUSIONS

The presence of the clinical symptoms associated with LA exposure and high FeNO levels should prompt further medical assessments in LA workers. Although EBC-H₂O₂ levels do not seem to reflect eosinophilic inflammation, serum SP-A levels could be used to monitor progression from rhinitis to asthma.

Association of polycyclic aromatic hydrocarbons exposure with atherosclerotic cardiovascular disease risk: A role of mean platelet volume or club cell secretory protein

BACKGROUND

Inflammation may play an important role in the association between exposure to polycyclic aromatic hydrocarbons (PAHs) and atherosclerotic cardiovascular disease (ASCVD) risk. However, the underlying mechanisms remain unclear.

OBJECTIVES

To investigate the association of PAHs exposure with ASCVD risk and effects of mean platelet volume (MPV) or Club cell secretory protein (CC16) on the association.

METHODS

A total of 2022 subjects (689 men and 1333 women) were drawn from the baseline Wuhan residents of the Wuhan-Zhuhai Cohort study. Data on demography and the physical examination were obtained from each participant. Urinary monohydroxy PAH metabolites (OH-PAHs) levels were measured by a gas chromatography-mass spectrometry. We estimated the association between each OH-PAHs and the 10-year ASCVD risk or coronary heart disease (CHD) risk using logistic regression models, and further analyze the mediating effect of MPV or plasma CC16 on the association by using structural equation modeling.

RESULTS

The results of multiple logistic regression models showed that some OH-PAHs were positively associated with ASCVD risk but not CHD risk, including 2-hydroxyfluoren (β = 1.761; 95% CI: 1.194-2.597), 9-hydroxyfluoren (β = 1.470; 95% CI: 1.139-1.898), 1-hydroxyphenanthrene (β = 1.480; 95% CI: 1.008-2.175) and ΣOH-PAHs levels (β = 1.699; 95% CI: 1.151-2.507). The analysis of structural equation modeling shows that increased MPV and increased plasma CC16 levels contributed 13.6% and 15.1%, respectively, to the association between PAHs exposure and the 10-year ASCVD risk (p < 0.05).

CONCLUSIONS

Exposure to PAHs may increase the risk of atherosclerosis, which was partially mediated by MPV or CC16.

High Baseline Serum Clara Cell 16 kDa Predicts Subsequent Lung Disease Worsening in Systemic Sclerosis

OBJECTIVE

Clara cell secretory protein (CC16) is a sensitive marker of bronchial epithelial cell damage. The CC16 serum level is elevated in patients with pulmonary fibrosis, but its predictive value on lung disease progression has not yet been studied. We aimed to assess the value of serum CC16 concentration in predicting lung disease deterioration in patients with systemic sclerosis (SSc).

METHODS

We prospectively analyzed and followed 106 patients with SSc during a 4-year period for the risk of developing combined deleterious event, defined as a 10% decrease in total lung capacity or forced vital capacity from baseline, or death, according to serum CC16 at inclusion. Receiver-operating characteristic (ROC) curve analysis was performed for prediction of events during the first 2 years after inclusion. Cumulative risks of combined events were computed by Kaplan-Meier analysis.

RESULTS

The best cutoff level of serum CC16 for prediction of a combined event was 33 ng/ml, with 76% sensitivity and 65% specificity (area under the ROC curve: 0.71, 95% CI 0.61-0.81, p < 0.0001). Progression of lung disease evaluated by a mean time-to-event differed between patients with high baseline serum CC16 (42.8 mos, 36.3-49.3) and those with low serum CC16 (56.3 mos, 50.9-61.7; log-rank test, p < 0.001). After adjustment for age, duration of disease, clinical and lung function measures, the risk of combined event occurrence in patients with high serum CC16 was significantly higher than in those with low CC16 (HR 2.9, 1.2-6.75, p < 0.05).

CONCLUSION

High baseline serum CC16 predicts lung disease worsening in patients with SSc.