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.

Predictive Value of Serum Markers SFRP1 and CC16 in Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Background

Chronic obstructive pulmonary disease (COPD) patients are particularly vulnerable to acute exacerbation, resulting in a huge socioeconomic burden.

Objective

In this study, we evaluated the value of serum secreted frizzled-related protein 1 (SFRP1) and Clara cell-secreted protein (CC16) in predicting the risk of acute exacerbations in patients with COPD.

Methods

The study included 123 COPD patients admitted to our hospital from May 2020 to June 2021, including 65 patients in stable stage (STCOPD group), 58 patients in acute exacerbation stage (AECOPD group), and 60 healthy volunteers (control group). Serum SFRP1 and CC16 levels were detected by enzyme-linked immunosorbent assay (ELISA). The receiver operating characteristics curve (ROC) analysis was performed to evaluate the sensitivity and specificity of serum SFRP1 and CC16 for predicting the risk of acute exacerbation in COPD patients.

Results

The age among groups is significantly different, but there is no difference in the gender and body mass index (BMI). The level of serum SFRP1 in the AECOPD group was significantly higher than that in the STCOPD group and the control group, and the level of serum CC16 was lower than that in the STCOPD group and the control group. Serum SFRP1 was negatively correlated with forced expiratory volume in one second (FEV₁)/forced vital capacity (FVC) (r = −0.473, P < 0.001). Serum CC16 was positively correlated with FEV₁/FVC (r = 0.457, P < 0.001). The area under the curve (AUC), sensitivity, and specificity of SFRP1 for predicting the risk of exacerbation was 0.847 (95% CI: 0.775 to 0.920), 86.20%, and 80.00%. The AUC, sensitivity, and specificity of CC16 for predicting the risk of exacerbation were 0.795 (95% CI: 0.711 to 0.879), 74.10%, and 86.20%.

Conclusions

These findings suggest that SFRP1 and CC16 may be useful serum markers for predicting the risk of exacerbation in COPD patients.

Secretoglobins in the big picture of immunoregulation in airway diseases

The proteins of the secretoglobin (SCGB) family are expressed by secretory tissues of barrier organs. They are embedded in immunoregulatory and anti-inflammatory processes of airway diseases. This review particularly illustrates the immune regulation of SCGBs by cytokines and their implication in the pathophysiology of airway diseases. The biology of SCGBs is a complex topic of increasing importance, as they are highly abundant in the respiratory tract and can also be detected in malignant tissues and as elements of immune control. In addition, SCGBs react to cytokines, they are embedded in Th1 and Th2 immune responses, and they are expressed in a manner dependent on cell maturation. The big picture of the SCGB family identifies these factors as critical elements of innate immune control at the epithelial barriers and highlights their potential for diagnostic assessment of epithelial activity. Some members of the SCGB family have so far only been superficially examined, but have high potential for translational research.

Circulating Secretoglobin Family 1A Member 1 (SCGB1A1) Levels as a Marker of Biomass Smoke Induced Chronic Obstructive Pulmonary Disease

Secretoglobin family 1A member 1 (SCGB1A1) alternatively known as club cell protein 16 is a protective pneumo-protein. Decreased serum levels of SCGB1A1 have been associated with tobacco smoke induced chronic obstructive pulmonary disease (TS-COPD). Exposure to biomass smoke (BMS) is an important COPD risk factor among women in low and lower-middle income countries. Therefore, in a cross-sectional study (n = 50/group; total 200 subjects) we assessed serum SCGB1A1 levels in BMS-COPD subjects (11 male, 39 female) compared to TS-COPD (all male) along with TS-CONTROL (asymptomatic smokers, all male) and healthy controls (29 male, 21 female) in an Indian population. Normal and chronic bronchitis like bronchial mucosa models developed at the air–liquid interface using human primary bronchial epithelial cells (3 donors, and three replicates per donor) were exposed to cigarette smoke condensate (CSC; 0.25, 0.5, and 1%) to assess SCGB1A1 transcript expression and protein secretion. Significantly (p < 0.0001) decreased serum SCGB1A1 concentrations (median, interquartile range, ng/mL) were detected in both BMS-COPD (1.6; 1.3–2.4) and TS-COPD (1.8; 1.4–2.5) subjects compared to TS-CONTROL (3.3; 2.9–3.5) and healthy controls (5.1; 4.5–7.2). The levels of SCGB1A1 were positively correlated (r = 0.7–0.8; p < 0.0001) with forced expiratory volume in 1 s, forced vital capacity, their ratios, and exercise capacity. The findings are also consistent within the BMS-COPD sub-group as well. Significantly (p < 0.03) decreased SCGB1A1 concentrations were detected with severity of COPD, dyspnea, quality of life, and mortality indicators. In vitro studies demonstrated significantly (p < 0.05) decreased SCGB1A1 transcript and/or protein levels following CSC exposure. Circulating SCGB1A1 levels may therefore also be considered as a potent marker of BMS-COPD and warrant studies in larger independent cohorts.

Effect of pressure-controlled ventilation-volume guaranteed mode combined with individualized positive end-expiratory pressure on respiratory mechanics, oxygenation and lung injury in patients undergoing laparoscopic surgery in Trendelenburg position

The study aimed to investigate the efficacy of PCV-VG combined with individual PEEP during laparoscopic surgery in the Trendelenburg position. 120 patients were randomly divided into four groups: VF group (VCV plus 5cmH₂O PEEP), PF group (PCV-VG plus 5cmH₂O PEEP), VI group (VCV plus individual PEEP), and PI group (PCV-VG plus individual PEEP). P_mean, P_peak, Cdyn, PaO₂/FiO₂, V_D/V_T, A-aDO₂ and Qs/Qt were recorded at T₁ (15 min after the induction of anesthesia), T₂ (60 min after pneumoperitoneum), and T₃ (5 min at the end of anesthesia). The CC16 and IL-6 were measured at T₁ and T₃. Our results showed that the P_mean was increased in VI and PI group, and the P_peak was lower in PI group at T₂. At T₂ and T₃, the Cdyn of PI group was higher than that in other groups, and PaO₂/FiO₂ was increased in PI group compared with VF and VI group. At T₂ and T₃, A-aDO₂ of PI and PF group was reduced than that in other groups. The Qs/Qt was decreased in PI group compared with VF and VI group at T₂ and T₃. At T₂, V_D/V_T in PI group was decreased than other groups. At T₃, the concentration of CC16 in PI group was lower compared with other groups, and IL-6 level of PI group was decreased than that in VF and VI group. In conclusion, the patients who underwent laparoscopic surgery, PCV-VG combined with individual PEEP produced favorable lung mechanics and oxygenation, and thus reducing inflammatory response and lung injury.

Clinical Trial registry: chictr.org. identifier: ChiCTR-2100044928

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.

Role of bone marrow-derived mesenchymal stem cells in alleviating pulmonary epithelium damage and extracellular matrix remodeling in a rat model of lung fibrosis induced by amiodarone

The therapeutic role of mesenchymal stem cells (MSCs) in cases of amiodarone (AD) induced pulmonary fibrosis (PF) has not been well studied. Also, the period required by MSCs to attain full therapeutic effectiveness has not yet been assessed. We investigated the potential curative effect of bone marrow-derived MSCs (BM-MSCs) and conditioned media (CM) from BM-MSCs on AD induced PF by focusing on pulmonary epithelium injury and repair, and extracellular matrix (ECM) remodeling. We used 64 Wistar rats divided into eight groups: negative control group; PF group; three PF groups treated with BM-MSCs for 1, 2 or 4 months; and three PF groups treated with CM for 1, 2 and 4 months. Serum levels of Clara cell secretory protein (CC16) and keratinocyte growth factor (KGF) were measured. Gene expression of type I collagen (COL1A1) and connective tissue growth factor (CTGF) was evaluated in pulmonary tissue. Treatment of PF challenged rats with BM-MSCs or CM caused reduced CC16 levels, increased KGF levels, reduced expression of COL1A1 and CTGF, histological improvement following lung injury, and decreased collagen accumulation. Treatment with BM-MSCs exhibited greater amelioration of PF than CM. BM-MSCs or CM treatment for 2 and 4 months exhibited better resolution of fibrosis than treatment for 1 month. BM-MSCs are promising for treating PF due to their attenuation of ECM deposition in addition to alleviating pulmonary epithelium damage and initiating its repair.

Reduced Serum Concentration of CC16 Is Associated with Severity of Chronic Obstructive Pulmonary Disease and Contributes to the Diagnosis and Assessment of the Disease

Background

The aim of this study was to reveal the correlations between serum concentration of Clara cell secretory protein (CC16) and clinical parameters of stable chronic obstructive pulmonary disease (COPD).

Patients and Methods

Serum concentration of CC16 was determined by enzyme-linked immunosorbent assay (ELISA). The correlations between serum concentration of CC16 and clinical parameters was performed by linear correlation analysis and multiple linear regression analysis. The sensitivity and specificity of serum CC16 for differential diagnosis of COPD were determined by receiver operator characteristic curve (ROC).

Results

The serum concentration of CC16 was down-regulated in stable COPD patients compared with healthy control group (p < 0.05). The decreased serum CC16 was negatively related to smoking (p < 0.05), GOLD grading (p < 0.005), mMRC score (p < 0.05) and medical history (p < 0.05) of patients, but positively correlated with pulmonary function (p < 0.05). The smoking, FEV1/FVC values, COPD grading and mMRC scores all affected the concentration of CC16 (p < 0.05). The decreased CC16 was an independent risk factor in the process of deterioration of lung function. The sensitivity and specificity of serum CC16 for identifying COPD reached to 65.3% and 75%.

Conclusion

Decreased serum concentration of CC16 correlated with the disease progression of COPD, suggesting that it can be used as an indicator contributing to the diagnosis and assessment of COPD.

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.

Urinary polycyclic aromatic hydrocarbon metabolites, Club cell secretory protein and lung function

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAHs) has been associated with lung function decline. However, the underlying mechanisms for the association remain unclear.

OBJECTIVES

To explore potential role of a lung epithelial biomarker, Club cell secretory protein (CC16), in associations between PAH exposures and lung function decline.

METHODS

We investigated 3384 adults from the Wuhan-Zhuhai cohort, and followed up at three years after first examination. Linear mixed models was used to quantify dose-response relationships between urinary monohydroxylated PAH metabolites (OH-PAHs) and lung function, as well as OH-PAHs and plasma CC16. Mediation analysis was conducted to investigate role of CC16 in the association between OH-PAHs and lung function. We also estimated the relationships between OH-PAHs and lung function change in three years among participants with different levels of CC16.

RESULTS

Each 1-unit increase of log-transformed total urinary high and low molecular weight OH-PAHs (∑HMW OH-PAH and ∑LMW OH-PAHs) were associated with a 22.59 and 25.25ml reduction of FEV₁ respectively, while∑HMW OH-PAH was associated with a 30.38ml reduction of FVC. Moreover, these negative associations between OH-PAHs and lung function levels were significant only among low CC16 group (<15.83ng/ml). CC16 concentration decreased monotonically with increased high molecular weight OH-PAHs (∑HMW OH-PAHs) when ∑HMW OH-PAH concentration was over 0.67μg/mmol Cr. CC16 mediated 22.13% of the association between ∑HMW OH-PAH and FVC among individuals with higher ∑HMW OH-PAH. After three years of follow-up, subjects with low level of plasma CC16 had a significant decline of FVC when exposed to high level of ∑HMW OH-PAH.

CONCLUSIONS

CC16 play an important role in the association between high molecular weight PAHs and FVC. Individuals with low plasma CC16 level might suffer a decline in lung function when exposed to high level of high molecular weight PAHs.

Role of biomarkers in acute traumatic lung injury

In severely injured patients severe thoracic trauma is common and can significantly influence the outcome of these critically ill patients by increased rates of mainly pulmonary complications. Furthermore, patients who sustained thoracic trauma are at increased risk for Acute Lung Injury (ALI) or Adult Respiratory Distress Syndrome (ARDS). Therapeutic options are limited, basically consisting of prophylactic antibiotic therapy and changing patient's positions. It is known, that ALI and ARDS differ clinically and pathobiologically from ALI/ARDS caused by other reasons, but the exact pathology remains elusive. Due to that no reliable predictive or surveillance biomarkers could be established for clinical diagnosis and identification of patients at high risk for acute traumatic lung injury. Nevertheless, there are plenty of promising markers that need to be further elucidated in larger case numbers and multicenter studies. This article sums up the recent status of those promising clinical biomarkers.

Clinical study on the changes of lung-specific proteins: CC16 after lung contusion

The aim of the present study was to examine the clinical value of continuously monitoring serum CC16 levels in diagnosing pulmonary contusion, estimating its severity degree and predicting disease progression. Thirty-one acute trauma patients with lung contusion diagnosed by chest computed tomography (CT) were included, and chest CT was re-examined on day 1, 3 and 7 after injury. Calculating all the contusion volume by the Siemens syngo volume calculation program, complications such as pleural effusion or atelectasis were observed and recorded. ELISA was employed to measure the levels of CC16 in all the patients for seven days, and another 15 serum samples were obtained from healthy volunteers to provide the reference value. Correlation analysis was further conducted for the CC16 levels and pulmonary contusion volume and its variations. Serum concentrations of CC16 in all the lung contusion patients were significantly higher than those in the controls, and reached a peak value on the first day. However, the contusion damage area shown in CT gradually increased with the occurrence of atelectasis and pleural effusion. The maximum volume of lung contusion had a positive correlation to the initial and average concentrations of CC16, and changes in the contusion volume were positively correlated with the initial concentration. The increased concentration of CC16 after lung contusion is an important reference for diagnosis, and may portend the possibility of further progress, while continuously monitoring CC16 serum levels in patients may provide the basis for clinical decision-making.

Diurnal physiological and immunological responses to a 10-km run in highly trained athletes in an environmentally controlled condition of 6 °C

Purpose

The Clara cell protein CC16, secreted from Clara cells in the lung, is discussed as a potential biomarker for toxic effects on the airways. An increased concentration of CC16 in serum may be caused by increased permeability of the lungs. To investigate the changes in P-CC16 in response to an intense exercise bout performed at different times of day (9 am and 4 pm) of highly trained individuals.

Method

Using a crossover randomized design, 8 runners (mean VO_2max 71 ml kg⁻¹ min⁻¹, SD 6) performed a 10-km time trial run, at 9 am and 4 pm, in an environmental chamber set at 6 °C. Lung function tests and blood sampling occurred at baseline, immediately post and 1 h post time trial.

Result

Diurnal differences (P < 0.05) were found for blood neutrophil and lymphocyte counts; with higher values at 4 pm. P-CC16 was higher at the pre- and post-trial time point at 9 am compared to 4 pm. Lung function was not different between or within trials.

Conclusion

Morning trial in cold condition caused more physiological strain compared to the same trial in the evening. However, this extra stress caused by zeitgebers could be a useful strategy for athletes, coaches, and general population to improve their running performance and protect their health in cold conditions in the long-term plan.

Clara cell protein 16: A biomarker for detecting secondary respiratory complications in patients with multiple injuries

BACKGROUND

Clara cell protein 16 (CC16) has recently gained acceptance as a blood biomarker for detecting direct and indirect lung injury. Although the early elevation of CC16 serum levels has been shown to correlate with pulmonary damage in patients with multiple injuries, the subsequent time course of CC16 serum levels has not been investigated in these patients.

METHODS

Fifty-eight patients with multiple injuries, 32 with severe thoracic injury, and 12 healthy volunteers were enrolled in this study. CC16 serum levels were measured at the time they were admitted to the trauma ward "time 0" and subsequently until day 14 using the enzyme-linked immunosorbent assay technique. The correlation between CC16 serum levels and severe lung injury, onset of nosocomial pneumonia, acute respiratory distress syndrome or acute lung injury, and organ failure was measured. In addition, areas under the receiver operating characteristic curve were calculated (p < 0.05 = significant).

RESULTS

In patients with lung injury, initial "time 0" median CC16 values were significantly elevated (11.2 ng/mL) compared with patients without severe thoracic injury (6.9 ng/mL) and controls (6.3 ng/mL). The observed elevation in serum CC16 declined to control values within 12 to 24 hours after trauma unless patients secondarily developed pneumonia. In the latter patients, median CC16 serum levels were significantly elevated (14.5 ng/mL) at the onset of pneumonia compared with their levels (7.3 ng/mL) 1 day before. In contrast, no secondary elevation in CC16 serum levels was observed in patients without severe lung injury within the same 24-hour period. The area under the receiver operating characteristic curve for serum CC16 and pneumonia was 0.79 (0.62-0.97; p = 0.0011).

CONCLUSION

Our results confirm the previously described association between initial elevation in CC16 serum levels and severe thoracic injury in patients with multiple injuries. In addition, we found that the initial elevation in CC16 serum levels declines to control values within the first day after trauma and that a secondary elevation indicates respiratory complications.

LEVEL OF EVIDENCE

Diagnostic study, level II.

Circulating levels of Clara cell protein 16 but not surfactant protein D identify and quantify lung damage in patients with multiple injuries

BACKGROUND

Almost 60% of all patients with severe multiple injuries sustain severe chest trauma with aggravating effect on morbidity and mortality. Diagnosis of lung contusion is performed by early posttraumatic multislice computed tomography. Because this diagnostic procedure requires time, resources, and exposure to radiation, a noninvasive approach with easy follow-up measurements is warranted.

METHODS

Serum levels of Clara cell protein 16 (CC16) and surfactant protein D as lung-specific biomarkers were obtained on admission from 104 patients with multiple injuries using enzyme-linked immunosorbent assay technique. Patients were divided into those with severe lung injury ([LI]; n = 68) and without LI (NLI; n = 36). Nonsmoking healthy volunteers served as controls. In addition, volume of lung contusions were calculated planimetrically on serial multislice computed tomography scans obtained after admission. Factors influencing CC16 serum levels were determined in uni- and multivariate analyses, and Spearman rank coefficients were calculated for correlations.

RESULTS

Patients with LI showed a significant (p < 0.05) elevation of median CC16 levels (10.2 ng/mL) compared with NLI patients (5.4 ng/mL) and controls (5.2 ng/mL). Serum CC16 levels correlated with the volume of lung contusions (r = 0.78, p < 0.0001) and were not influenced by overall injury severity, age, gender, or preclinical ventilation. In contrast, circulating surfactant protein D levels were not associated with the presence of LI or the extent of lung contusions.

CONCLUSIONS

Our results advocate CC16 as a potential biomarker for LI in severely injured patients because of its high correlation with the volume of contused lung parenchyma. Therefore, this parameter may allow a specified initial treatment of patients with multiple injuries.