Gene-environment interaction from international cohorts: impact on development and evolution of occupational and environmental lung and airway disease

The Nicotinic Receptor Polymorphism rs16969968 Is Associated with Airway Remodeling and Inflammatory Dysregulation in COPD Patients

Genome-wide association studies unveiled the associations between the single nucleotide polymorphism rs16969968 of CHRNA5, encoding the nicotinic acetylcholine receptor alpha5 subunit (α5SNP), and nicotine addiction, cancer, and COPD independently. Here, we investigated α5SNP-induced epithelial remodeling and inflammatory response in human COPD airways. We included 26 α5SNP COPD patients and 18 wild-type α5 COPD patients in a multi-modal study. A comparative histologic analysis was performed on formalin-fixed paraffin-embedded lung tissues. Isolated airway epithelial cells from bronchial brushings were cultivated in the air-liquid interface. Broncho-alveolar fluids were collected to detect inflammatory mediators. Ciliogenesis was altered in α5SNP COPD bronchial and bronchiolar epithelia. Goblet cell hyperplasia was exacerbated in α5SNP small airways. The broncho-alveolar fluids of α5SNP COPD patients exhibited an increase in inflammatory mediators. The involvement of the rs16969968 polymorphism in airway epithelial remodeling and related inflammatory response in COPD prompts the development of innovative personalized diagnostic and therapeutic strategies.

Chr15q25 Genetic Variant rs16969968 Alters Cell Differentiation in Respiratory Epithelia

The gene cluster region, CHRNA3/CHRNA5/CHRNB4, encoding for nicotinic acetylcholine receptor (nAChR) subunits, contains several genetic variants linked to nicotine addiction and brain disorders. The CHRNA5 single-nucleotide polymorphism (SNP) rs16969968 is strongly associated with nicotine dependence and lung diseases. Using immunostaining studies on tissue sections and air-liquid interface airway epithelial cell cultures, in situ hybridisation, transcriptomic and cytokines detection, we analysed rs16969968 contribution to respiratory airway epithelial remodelling and modulation of inflammation. We provide cellular and molecular analyses which support the genetic association of this polymorphism with impaired ciliogenesis and the altered production of inflammatory mediators. This suggests its role in lung disease development.

Interleukin 1α and 1β gene variations are associated with tuberculosis in silica exposed subjects

INTRODUCTION

Silicosis is a fibrotic lung disease resulting from the inhalation of crystalline silica and can be classified as simple or complicated according to the International Labour Organization criteria. Furthermore, individuals exposed to crystalline silica also have a higher risk for the development of tuberculosis (Tb). The contribution of inflammatory cytokines to the risk of silicosis and Tb in different populations has previously been reported. Since genetic background might be related to susceptibility to silicosis and Tb, the study of polymorphisms within IL-1α, IL-1β, and tumor necrosis factor protein-coding genes may contribute to elucidating the genetic basis of these diseases.

METHODS

Single nucleotide polymorphisms (SNPs) were genotyped by polymerase chain reaction using restriction fragment length polymorphism or by Taqman methodology, in a sample of 102 silica-exposed patients from Brazil.

RESULTS

No significant associations were observed between the SNPs studied and the severity of silicosis. However, significant associations were found between Tb and the C allele (odds ratio [OR] = 1.93, 95% confidence interval [CI], 1.01-3.73) and the CC genotype (OR = 2.34, 95% CI, 1.04-5.31) of IL1A -899C>T. The IL1B +3954C>T polymorphism also showed an association with Tb (T allele dominant model OR = 2.38, 95% CI, 1.04-5.41).

CONCLUSION

These preliminary results demonstrate that the IL1A and IL1B gene variations may contribute to some extent to susceptibility to Tb, but not silicosis. However, additional studies are still needed to confirm these results.

Dust induces lung fibrosis through dysregulated DNA methylation

Pneumoconiosis is a serious occupational disease that often occurs to coal workers with no early diagnosis and effective treatment at present. Diffuse pulmonary fibrosis is the major pathological change of pneumoconiosis, and its mechanism is still unclear. Epigenetics is involved in the development of many diseases, and it is closely associated with fibrosis. In this study, we investigated whether DNA methylation contributes to the pathogenesis of pulmonary fibrosis in pneumoconiosis. By exposure to coal dust or silica dust, we established the models of coal worker's pneumoconiosis (CWP), which showed an increased expression of COL-I, COL-III. We further found that DNMT1, DNMT3a, DNMT3b, MBD2, MeCP2 protein expression changed. Pretreatment with DNMT inhibitor 5-aza-dC reduced expression of COL-I, COL-III, and reduced pulmonary fibrosis. In summary, our results showed that DNA methylation contributes to dust-induced pulmonary fibrosis and that it may serve as a theoretical basis for testing DNA methyltransferase inhibitors in the treatment of CWP.

The association of LAMB1 polymorphism and expression changes with the risk of coal workers' pneumoconiosis

BACKGROUND

Pneumoconiosis is a serious occupational disease worldwide, which is characterized by irreversible and diffuse lung fibrotic lesions. Laminin beta 1(LAMB1) is widely expressed in tissues and it is crucial for both lung morphogenesis and physiological function. In this study, we explored the association between LAMB1 rs4320486 and risk of pneumoconiosis in a Chinese population, as well as its mechanisms.

METHODS

In this case-control study, 600 CWP patients and 605 controls were genotyped for the LAMB1 rs4320486 polymorphism using TaqMan methods. Luciferase reporter assay was used to assess the LAMB1 transcriptional activities. The protein levels in cells and tissues were detected by western blot, and mRNA levels were determined by qRT-PCR.

RESULTS

Logistic regression analysis revealed that individuals with LAMB1 rs4320486 CT/TT genotypes had a significantly decreased risk of CWP (adjusted OR = 0.78, 95%CI = 0.64-0.94), compared with individuals with CC genotypes. Luciferase assays showed that the LAMB1 rs4320486(C > T) substitution could decrease the expression of LAMB1. Compared with normal groups, mRNA levels of LAMB1 were up-regulated in lung tissues of patients with pulmonary fibrosis. Additionally, expressions of LAMB1 and α-SMA were enhanced progressively, along with the development of lung fibrosis, while E-cadherin decreased.

CONCLUSIONS

In this study, the functional LAMB1 rs4320486 mutation was associated with a decreased risk of CWP in a Chinese population, probably owing to the reduced activity of LAMB1 transcription. LAMB1 expression was increased in the progress of lung fibrosis, which suggests that LAMB1 may affect the initiation and progression of pneumoconiosis, or serve as a potential biomarker of pneumoconiosis for diagnosis and genetic susceptibility.

Usefulness of Biomarkers in Work-Related Airway Disease

Determination of biomarkers may be useful in the surveillance of occupational exposure and workers' health. The possibility of predicting development/clinical course of specific disorders or current disease, diagnosing in early steps, and health condition monitoring is a real necessity. Various agents present in the workplace environment (or their metabolites) can be measured in samples possessed from human body (blood and urine, saliva, etc.). On the other hand, inhalant exposure may induce specific or non-specific, local or systemic, acute or chronic biological response expressed by synthesis or releasing specific or non-specific substances/mediators that also can be determined in blood, nasal and bronchial lavage or sputum, tear fluid, exhaled breath, etc. The least is known about genetic markers which may predict individual susceptibility to develop some work-related disorders under the influence of occupational exposure. Due to common exposure to inhalant agents at workplace, researches on biomarkers that allow to inspect the impact of exposure to humans' health are still needed. The authors of this article summarize the utility of biomarkers' determination in work-related airway diseases in a recent clinical approach.

Prevalence Characteristics of Coal Workers' Pneumoconiosis (CWP) in a State-Owned Mine in Eastern China

Coal Workers' Pneumoconiosis (CWP) is the primary occupational disease in China. However, information about the definite prevalence of CWP is only partially available. The aims of our study were to assess the prevalence characteristics of CWP in a state-owned coal mine, evaluate the effects of control measures and develop further preventive strategies for CWP. The total study population included 495 cases who were diagnosed with CWP from the construction of this coal mine to the end of October 2014. Individuals' information, including duration of dust exposure, job titles, age as first diagnosis, stages of CWP, CWP progress, complications with pulmonary tuberculosis, death and others were collected and analyzed. The results showed that 71.11% of 495 CWP cases were stage I and 90.71% were involved in tunneling or coal mining. The mean dust exposure period in CWP patients was 26.7 years, the mean latent period was 29.3 years and the mean diagnosed age was 50.3 years old. The proportion of CWP diagnosed after ending dust exposure were remarkably increased with the time passing. Among the CWP cases, 36 (7.27%) were complicated with pulmonary tuberculosis. The mortality of patients with stage III was the highest (60.71%) (p < 0.0001). Our data obviously show that more strict policies to protect coal miners are needed to be implemented in China, especially for tunneling and mining workers.