Occupational lung diseases in Australia

Cluster analysis of phenotypes, job exposure, and inflammatory patterns in elderly and nonelderly asthma patients

BACKGROUND

Asthma has been identified as different phenotypes due to various risk factors. Age differences may have potential effects on asthma phenotypes. Our study aimed to identify potential asthma phenotypes among adults divided by age as either younger or older than 65 years. We also compared differences in blood granulocyte patterns, occupational asthmagens, and asthma control-related outcomes among patient phenotype clusters.

METHODS

We recruited nonelderly (<65 years old) (n = 726) and elderly adults (≥65 years old) (n = 201) with mild-to-severe asthma. We conducted a factor analysis to select 17 variables. A two-step cluster analysis was used to classify subjects with asthma phenotypes, and a discriminant analysis was used to verify the classification of cluster results.

RESULTS

There were three clusters with different characteristics identified in both the nonelderly and elderly asthmatic adults. In the nonelderly patient group, cluster 2 (obese, neutrophilic phenotypes) had a 1.85-fold significantly increased risk of asthma exacerbations. Cluster 3 (early-onset, atopy, and smoker with an eosinophil-predominant pattern) had a 2.37-fold risk of asthma exacerbations and higher oral corticosteroid (OCS) use than cluster 1 (late-onset and LMW exposure with paucigranulocytic blood pattern). Among elderly patients, cluster 2 had poor lung function and more ex-smokers. Cluster 3 (early-onset, long asthma duration) had the lowest paucigranulocytic blood pattern percentages in the elderly group.

CONCLUSIONS

The novelty of the clusters was found in age-dependent clusters. We identified three distinct phenotypes with heterogeneous characteristics, asthma exacerbations and medicine use in nonelderly and elderly asthmatic patients, respectively. Classification of age-stratified asthma phenotypes may lead to precise identification of patients, which provides personalized disease management.

Small airway dysfunction in pneumoconiosis: a cross-sectional study

Background

Although several histological studies have documented airway inflammation and remodelling in the small airways of dust-exposed workers, little is known regarding the prevalence and risk factors of small airway dysfunction (SAD) in pneumoconiosis. The present study investigated the prevalence and characteristics of spirometry-defined SAD in pneumoconiosis and assessed the risk factors for associated with SAD.

Methods

A total of 1255 patients with pneumoconiosis were invited to participate, of whom 1115 patients were eligible for final analysis. Spirometry was performed to assess SAD using the following three indicators: maximal mid-expiratory flow and forced expiratory flow 50% and 75%. SAD was defined as at least two of these three indicators being less than 65% of predicted value. Logistic regression analyses were used to analyse the relationships between clinical variables and SAD.

Results

Overall, 66.3% of patients with pneumoconiosis had SAD, among never-smokers the prevalence of SAD was 66.7%. The proportion of SAD did not differ among the subtypes of pneumoconiosis. In addition, SAD was present across the patients with all stages of pneumoconiosis. Even among those with forced expiratory volume in 1 s (FEV₁) ≥ 80% and FEV₁/forced vital capacity ratio ≥ 70%, 40.8% of patients had SAD. Patients with SAD were older than patients without SAD, more likely to be women and heavy smokers. Importantly, patients with SAD had more severe airflow obstruction, air trapping, and diffusion dysfunction. All patients with both pneumoconiosis and chronic obstructive pulmonary disease had SAD. Based on multivariate analysis, overall, aged 40 years and older, female sex, heavy smoking, body mass index ≥ 25.0 kg/m² and pneumoconiosis stage III were significantly associated with increased risk of SAD. Among the never smokers, risk factors for SAD included female sex, BMI ≥ 25.0 kg/m², pneumoconiosis stage II and stage III

Conclusion

Spirometry-defined SAD is one of the common functional abnormalities caused by occupational dust exposure and should be taken into account when monitoring respiratory health of workers to guide the early precautions and management in pneumoconiosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01929-9.

Predictors of psychological stress in silica-exposed workers in the artificial stone benchtop industry

Background and objective

Artificial stone benchtops are a popular kitchen product, but dust from their preparation and installation contains respirable crystalline silica, which causes silicosis. Silicosis is a preventable, permanent lung disease. The aim of this study was to assess mental health in workers from the artificial stone benchtop industry at risk of silicosis.

Methods

Workers from the artificial stone benchtop industry undergoing assessment for silica‐associated disease were included. Information on demographics; occupational, medical and smoking history; modified Medical Research Council dyspnoea scale; Perceived Stress Scale (PSS‐10) questionnaire; spirometry; and chest x‐ray was collected. Univariate and multivariate regression analyses were conducted.

Results

Of the 547 participants, the majority were men, aged under 45 years, in the industry for less than 10 years. With each increase of dyspnoea score, PSS‐10 scores increased. Higher PSS‐10 scores were also observed in those no longer in the industry, with a history of anxiety or depression, attending assessment early in the programme and a medium exposure duration. Participants who used an interpreter reported lower stress. No difference was observed across job title, age, sex, smoking, spirometry or chest x‐ray categories after multivariate analysis.

Conclusion

This study identified workers with dyspnoea as likely to report higher stress. Other factors, such as leaving the industry, early attendance and a history of anxiety or depression, are also helpful in identifying workers at risk of poorer mental health outcomes.

This study describes psychological stress scores in silica‐exposed workers from the artificial stone benchtop industry and identifies predictors of elevated stress.

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Silicon, an important exposure marker in vivo in silicosis research

PURPOSE

The degree of silicosis exposure is closely related to the progress of silicosis. At present, we use animal and human studies to explore whether silicon can be an important exposure marker in the development of silicosis.

METHODS

Rats were randomly divided into 2 groups: (1) controls; and (2) silicosis. Rats in the silicosis group were killed at 4, 8, 12, 16, 24 h, 3, 7, 14, 21, and 28 days. Hematoxylin-eosin (HE) and immunohistochemistry (IHC) were performed to observe the histomorphology of lung tissue. The expression levels of CC16 and SP-D were detected using ELISA kits. In addition, we conducted a population study. Workers who have been selected to work in an iron mine for more than 1 year as research objects. The population was divided into four groups: silicosis exposure group (workers exposed to silica dust for more than 1 year in an iron mine were selected); patients group (silicosis patients); observation group (evidence of disease not meeting formal diagnostic criteria) and control group. Both the levels of trace silicon in the urine and blood of rats and human subjects were measured with ICP-MS.

RESULTS

Serum levels of silicon were immediately increased in rats exposed to silicon dust. Similarly, our population study revealed that the silicon level in the silica exposure group and the observing group (exposed but no obvious symptoms) were significantly increased over that of the control group (P < 0.05). In subjects with extended exposure to silica, the serum and urine silicon level in exposed workers appeared to rapidly increase, reaching its peak in 1-5 years, followed by a gradual decline thereafter. Workers exposed to dust for less than 10 years were divided into subgroups by 2-year limit. The levels of serum silicon, urine silicon, TGF-β1, and TNF-α were significantly higher than that of control group.

CONCLUSION

Changes of the serum levels of silicon occurred earlier than the expression of cytokines such as TNF-α, TGF-β1, CC16, and SP-D. The level of silicon in workers rapidly increased after exposure to silica, and the change occurred before the expression of TGF-β1 and TNF-α. As a whole, the findings suggest that determining the level of silicon in vivo might be an effective exposure marker in the diagnosis and pathogenesis of silicosis.

Increasing incidence of asbestosis worldwide, 1990-2017: results from the Global Burden of Disease study 2017

Global incidence and temporal trends of asbestosis are rarely explored. Using the detailed information on asbestosis from the Global Burden of Disease (GBD) 2017, we described the age-standardised incidence rate (ASIR) and its average annual percentage change. A Joinpoint Regression model was applied to identify varying temporal trends over time. Although the use of asbestos has been completely banned in many countries, the ASIR of asbestosis increased globally from 1990 to 2017. Furthermore, the most pronounced increases in ASIR of asbestosis were detected in high-income North America and Australasia. These findings indicate that efforts to change the asbestos regulation policy are urgently needed.

Trends in global, regional and national incidence of pneumoconiosis caused by different aetiologies: an analysis from the Global Burden of Disease Study 2017

OBJECTIVES

Pneumoconiosis remains a major global occupational health hazard and illness. Accurate data on the incidence of pneumoconiosis are critical for health resource planning and development of health policy.

METHODS

We collected data for the period between 1990 and 2017 on the annual incident cases and the age-standardised incidence rates (ASIR) of pneumoconiosis aetiology from the Global Burden of Disease Study 2017. We calculated the average annual percentage changes of ASIR by sex, region and aetiology in order to determine the trends of pneumoconiosis.

RESULTS

Globally, the number of pneumoconiosis cases increased by a measure of 66.0%, from 36 186 in 1990 to 60 055 in 2017. The overall ASIR decreased by an average of 0.6% per year in the same period. The number of pneumoconiosis cases increased across the five sociodemographic index regions, and there was a decrease in the ASIR from 1990 to 2017. The ASIR of silicosis, coal workers' pneumoconiosis and other pneumoconiosis decreased. In contrast, measures of the ASIR of asbestosis displayed an increasing trend. Patterns of the incidence of pneumoconiosis caused by different aetiologies were found to have been heterogeneous for analyses across regions and among countries.

CONCLUSION

Incidence patterns of pneumoconiosis which were caused by different aetiologies varied considerably across regions and countries of the world. The patterns of incidence and temporal trends should facilitate the establishment of more effective and increasingly targeted methods for prevention of pneumoconiosis and reduce associated disease burden.

miRNA sequencing reveals miRNA-4508 from peripheral blood lymphocytes as potential diagnostic biomarker for silica-related pulmonary fibrosis: A multistage study

BACKGROUND AND OBJECTIVE

This study aimed to identify miRNA as potential diagnostic biomarkers for silica-related pulmonary fibrosis (SPF).

METHODS

We first performed a comprehensive miRNA-seq screening in PBL of eight subjects exposed to silica dust (four individuals with SPF and four healthy controls). The promising miRNA were then evaluated in the first-stage validation using an independent GEO data set (GSE80555) of 6 subjects (3 individuals with SPF and 3 healthy controls), followed by a second-stage validation using 120 subjects exposed to silica dust (60 individuals with SPF and 60 healthy controls).

RESULTS

Thirty-five miRNA showed strong expression differences in miRNA-seq screening, while miRNA-4508 (P = 9.52 × 10^-3 ) was retained as a candidate after the first-stage validation (GSE80555), which was further confirmed in the second-stage validation with similar and strong effect (P = 9.93 × 10^-17 ). ROC analysis showed that miRNA-4508 could distinguish SPF cases from healthy controls with high AUC (0.886), with sensitivity of 81.7% and specificity of 86.7%. In addition, the miRNA-4508 upstream rs6576457 mutant A allele exhibited a strong association with susceptibility to SPF (OR = 1.64, 95% CI = 1.20-2.23, P = 0.002), while eQTL analysis revealed a potential association between different genotypes of rs6576457 and miRNA-4508 expression (P = 0.068) in 60 healthy subjects with silica dust exposure.

CONCLUSION

miRNA-4508 may be a potential diagnostic marker for SPF, and rs6576457, a functional variant of miRNA-4508, may affect SPF susceptibility. The detailed mechanism of action of this miRNA remains to be elucidated.

Transbronchial lung cryobiopsy: a novel confirmatory tool to diagnose asbestos-related pulmonary fibrosis

Asbestosis is diagnosed with a combination of historical, clinical and radiological findings in the absence of another cause. Histology is required when uncertainty exists, with lung biopsy via VATs being gold standard. Transbronchial cryobiopsy is becoming increasingly popular for diagnosing interstitial lung disease and may provide sufficient lung sample to demonstrate asbestosis. A 73 year old man presented with dyspnoea on a background of rheumatoid arthritis, previous methotrexate use and asbestos exposure. Examination revealed fine crackles in the mid and lower zones bilaterally without signs of pulmonary hypertension. The presence of pleural plaques and basal interstitial reticulation on HRCT was suggestive of asbestosis but histology was required to differentiate this from rheumatoid or methotrexate associated ILD. Samples of lung tissue were obtained via transbronchial cryobiopsy, demonstrating fibrosis and asbestos fibres consistent with asbestosis. Transbronchial cryobiopsy appears effective in obtaining sufficient parenchymal lung samples to diagnose asbestosis when clinical uncertainty exists.

Emerging Role of Immunosuppression in Diseases Induced by Micro- and Nano-Particles: Time to Revisit the Exclusive Inflammatory Scenario

Fibrosis, cancer, and autoimmunity developing upon particle exposure have been exclusively linked with uncontrolled inflammatory processes. The critical role of inflammation is now challenged by several contradictory observations indicating that the emergence of these chronic disorders may result from non-inflammatory events. A growing number of studies reveals that micro- and nano-particles can cause exaggerated and persistent immunosuppression characterized by the release of potent anti-inflammatory cytokines (IL-10 and TGF-β), and the recruitment of major regulatory immune cells (M2 macrophages, T and B regs, and MDSC). This persistent immunosuppressive environment is initially established to limit early inflammation but contributes later to fibrosis, cancer, and infection. Immunosuppression promotes fibroblast proliferation and matrix element synthesis and subverts innate and adaptive immune surveillance against tumor cells and microorganisms. This review details the contribution of immunosuppressive cells and their derived immunoregulatory mediators and delineates the mutual role of inflammatory vs. immunosuppressive mechanisms in the pathogenesis of chronic diseases induced by particles. The consideration of these new results explains how particle-related diseases can develop independently of chronic inflammation, enriches current bioassays predicting particle toxicity and suggests new clinical strategies for treating patients affected by particle-associated diseases.