Candidate gene polymorphisms associated with silicosis and coal workers' pneumoconiosis: a systematic review and meta-analysis

BACKGROUND

Silicosis and coal worker's pneumoconiosis primarily result from exposure to silica and coal dust. Despite similar exposure levels, individuals exhibit varying responses. This study aimed to address these gaps to explore the genetic factors influencing the development, severity, and associated complications.

METHODS

A systematic literature search was performed across four databases-PubMed, Embase, Web of Science, and Cochrane Library-until July, 2023. Qualitative and quantitative analyses were applied to identify candidate genes.

RESULTS

This study involved 83 articles and encompassed 545 individual studies, reviewing a total of 378 gene loci. After rigorous evaluation, we selected 8 candidate genes (TNFα-308, TNFα-238, GSTT1, IL-1α + 4845, IL-1β-511, IL-1β + 3953, IL-1RA + 2018, and IL-6-174) for meta-analysis. The analysis revealed that allele A of TNFα-308, allele A of TNFα-238, and allele C of IL-1RA + 2018 were identified as risk factors for the development of diseases.

CONCLUSIONS

This study established associations between specific genetic polymorphisms (TNFα-308, TNFα-238, and IL-1RA + 2018) and susceptibility to silicosis and coal worker's pneumoconiosis.

Association of rs4711998 of IL-17A, rs2275913 of IL-17A and rs763780 IL-17F gene polymorphisms with non-segmental vitiligo in a Mexican population

Vitiligo is the most common depigmenting disease characterized by achromic macules due to selective loss of melanocytes. The pathogenesis remains poorly elucidated, and multiple hypotheses exist regarding its pathogenesis. Evidence suggests that stress on melanocytes can result in activation of the immune system, and involvement of both activated cluster of differentiation (CD8+) cytotoxic and CD4+ T cells in the dysfunction, depigmentation, and apoptosis of melanocytes. Recent studies show that the interleukin 17 (IL-17) axis plays a central role in the pathogenesis of the disease. IL-17 is an important regulatory effector cytokine in this pathway. The aim of this study was to evaluate the association of IL-17A rs4711998 (-832A/G), IL-17A rs2275913 (-197G/A), and IL-17F rs763780 (7488A/G) with vitiligo in a Northeastern Mexican population. This was a case-control study and included 116 patients with vitiligo and 116 control subjects. Genotype characterization of IL-17A rs4711998 (-832A/G), IL-17A rs2275913 (-197G/A), and IL-17F rs763780 (7488A/G) was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. A p ≤ 0.05 was considered significant. It was observed that the combination of the genotypes GG/GA for IL-17F rs763780 (7488A/G) was associated with an increased risk for the development of vitiligo (OR 2.0943, 95% Cl 1.2375-3.5445, p = 0.0056). Regarding IL-17A rs4711998 (-832A/G) and IL-17A rs2275913 (-197G/A) genotyping, no association with vitiligo development was found. In conclusion, the SNP rs763780 in the IL-17F gene appears to be a risk factor for vitiligo development in this Mexican population and it may be useful in future studies, especially for the development of new therapies.

Genetic susceptibility in pneumoconiosis in China: a systematic review

OBJECTIVE

Pneumoconiosis, encompassing coal workers' pneumoconiosis (CWP), silicosis and asbestosis, is one of the most common occupational diseases in China. Previous studies revealed significant associations between genetic variations and pneumoconiosis risk among individuals in different countries. With the known variability of genetic makeup between ethnicities, susceptibility to pneumoconiosis due to genetic differences is likely to be ethnicity-specific. The present review aimed at providing a comprehensive overview on the association between genetic polymorphisms and susceptibility of pneumoconiosis, specifically among people in China.

METHODS

The literature search was performed in seven English and Chinese databases using keywords related to the review aim. An appraisal of the methodological quality of the included studies was conducted using the assessment tool derived from the Strengthening the Reporting of Genetic Association Studies (STREGA) statement.

RESULTS

Forty-five studies were included in this review. Genotypes of specific genes which are associated with the risk of CWP, silicosis and asbestosis were reported. Our findings showed that genes encoding inflammatory cytokines have been examined extensively, and they demonstrated an association between these genes and pneumoconiosis risk. Gene-environment interactions in pneumoconiosis susceptibility were also reported by a number of studies.

CONCLUSIONS

This review summarised the evidence demonstrating the association between genetic polymorphisms and pneumoconiosis susceptibility among people in China, and that various genotypes could modify their risk to develop pneumoconiosis. The findings prompt that identification of individuals at high pneumoconiosis risk through genetic screening and strategies limiting their exposure to dust could be a potential strategy for the control of this occupational disease in China.

Occupational exposure to crystalline silica and peripheral biomarkers: An update

Peripheral biomarkers are important tools for detecting occupational exposures to prevent the onset and/or progression of diseases. Studies that reveal early peripheral biomarkers are highly important to preserve the health of workers and can potentially contribute to diagnosing and/or prognosing occupational pathologies. Exposure to crystalline silica is a problem in several workplaces because it increases the risk of chronic obstructive pulmonary disease (COPD), tuberculosis, cancer, and pulmonary fibrosis, clinically defined as silicosis. Silicosis is diagnosed by chest radiography and/or lung tomography in advanced stages when there is a severe loss of lung function. Peripheral biomarkers can help in diagnosing early changes prior to silicosis and represent a highly important technical-scientific advance that is minimally invasive. This review aimed to investigate the biomarkers studied for evaluating occupational exposure to crystalline silica and to understand the recent advances in this area. Potential oxidative, inflammatory, and immunological biomarkers were reviewed, as well as routine biomarkers such as biochemical parameters. It was found that biomarkers of effect such as serum CC16 and l-selectin levels could represent promising alternatives. Additionally, studies have shown that neopterin levels in urine and serum can be used to monitor worker exposure. However, further studies are needed that include a greater number of participants, different times of exposure to crystalline silica, and a combination of silicosis patients and healthy volunteers. Evaluating the concentration of crystalline silica in occupational environments, its impact on biomarkers of effect, and alterations in lung function could contribute to revealing early health alterations in workers in a more robust manner.

Is individual genetic susceptibility a link between silica exposure and development or severity of silicosis? A systematic review

BACKGROUND

Silicosis is a lung disease of fibrotic nature resulting from the inhalation and deposition of dust containing crystalline silica. Subjects exposed to the same environmental factors may show distinct radiological manifestations, and since silicosis is known as a multifactorial disease, it is plausible that individual genetic susceptibility may play a role in the pathology. This review of the literature aims to provide an assessment of the present data on the genetic association studies in silicosis and describe the genes that potentially might influence silicosis susceptibility in silica-exposed individuals.

METHODS

We accessed the database of PubMed for articles published in English about interindividual genetic susceptibility to silicosis using terms related to the subject matter.

RESULTS

Following the evaluation process, 28 studies were included in this systematic review, including 23 original studies and 5 meta-analyses.

CONCLUSIONS

Regardless of the advances in the knowledge of the importance of gene variations in silicosis, more studies need to be performed, in particular, special polygenic and genome-wide investigations.

Tumor necrosis factor gene polymorphisms are associated with silicosis: a systemic review and meta-analysis

Studies investigating association between tumor necrosis factor (TNF) gene polymorphisms and silicosis susceptibility report conflicting results. The aim of this meta-analysis was to assess association between TNF gene polymorphisms and silicosis susceptibility. A systematic literature search was conducted to find relevant studies. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the strength of association. Finally, a total of 12 articles, involving 1990 silicosis patients and 1898 healthy controls were included in the meta-analysis. Overall, meta-analysis revealed a significant association between the TNF −308A allele and silicosis (OR = 1.348, 95%CI = 1.156–1.570, P<0.001). A significant association of AA+AG genotype of the TNF −308 A/G polymorphism with susceptibility to silicosis was also found (OR = 1.466, 95%CI = 1.226–1.753, P<0.001). After stratification by ethnicity, significant associations were detected under the genetic models (A allele and AA+AG genotype) for TNF −308A/G polymorphisms in the Asian population (P<0.05). Similarly, meta-analysis of the TNF −238A/G polymorphism revealed the same pattern as that shown by meta-analysis of TNF −308A/G. The meta-analysis suggests that the TNF −308A/G and −238A/G polymorphisms are associated with susceptibility to silicosis, especially in Asians.

Type 2 macrophages and Th2 CD4+ cells in interstitial lung diseases (ILDs): an overview

Interstitial lung diseases (ILDs) are a heterogeneous group characterized mainly by damage to pulmonary parenchyma, through histopathological processes such as granulomatous pneumopathy, inflammation and fibrosis. Factors that generate susceptibility to ILDs include age, exposure to occupational and environmental compounds, genetic, family history, radiation and chemotherapy/immunomodulatory and cigarette smoke. IFN-γ, IL-1β, and LPS are necessary to induce a classical activation of macrophages, whereas cytokines as IL-4 and IL-13 can induce an alternative activation in macrophages, through the JAK-STAT mediated signal transduction. M2 macrophages are identified based on the gene transcription or protein expression of a set of M2 markers. These markers include transmembrane glycoproteins, scavenger receptors, enzymes, growth factors, hormones, cytokines, and cytokine receptors with diverse and often yet unexplored functions. Fibrotic lung disorders may have a M2 polarization background. The Th2 pathway with an elevated CCL-18 (marker of M2) concentration in the bronchoalveolar lavage fluid (BALF) is linked to fibrosis in ILDs. Besides the role of M2 in tissue repair and ECM remodeling, activated fibroblasts summon and stimulate macrophages by producing MCP-1, M-CSF and other chemokines, as well as activated macrophages secrete cytokines that attract and stimulate proliferation, survival and migration of fibroblast mediated by platelet-derived growth factor (PDGF). (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 98-108).

Association between SNPs at IL-17A and IL-17F and susceptibility to accelerated silicosis

The association between single nucleotide polymorphisms (SNPs) in the interleukin (IL)-17 gene and silicosis has been evaluated in different populations. The aim of the present study was to analyze the association between SNPs at IL-17A (−832A/G) and IL-17F (+7488A/G) and susceptibility to accelerated silicosis in the Iranian Kurdish population. We studied 48 patients with accelerated silicosis and 62 controls. Genomic DNA was isolated using the “salting out” method. PCR-RFLP was performed for all SNPs typing. The frequencies of A/A, A/G, and G/G genotypes at IL-17A (−832A/G) were 4 (8.33%), 23 (47.92%), and 21 (43.75%) in patients and 5 (8.06%), 35 (56.45%), and 22 (35.48%) in controls, respectively. The frequencies of A and G alleles at IL-17 (−832A/G) were 31 (32.29%) and 65 (67.71%) in patients, and 45 (36.29%) and 79 (63.71%) in the controls, respectively. The frequencies of A/A, A/G, and G/G genotypes at IL-17F (+7488A/G) were 1 (2.08%), 47 (97.92%), and 0 (0%) in patients, and 11 (17.74%), 51 (82.26%), and 0 (0%) in the controls, respectively. The frequencies of A and G alleles at IL-17F (+7488A/G) were 49 (51.04%) and 47 (48.96%) in patients, and 73 (58.87%) and 51 (41.13%) in the controls, respectively. IL-17F (+7488A/G) genotype was more frequent among the cases compared with controls (97.92% vs. 82.26%). The frequency of the IL-17F (+7488A/G) genotype was significantly greater in patients with accelerated silicosis (odds ratio = 10.13 95%; confidence interval = 1.2–81.5; p = 0.008). The IL-17F (+7488A/G) genotype revealed a significantly increased risk of accelerated silicosis ( p < 0.05). The IL-17F (+7488 G) allele was associated with an increased risk of accelerated silicosis, but in the case of the IL-17A (−832A/G) polymorphism, a significant association was not observed.

Risk of occupational exposure to asbestos, silicon and arsenic on pulmonary disorders: Understanding the genetic-epigenetic interplay and future prospects

BACKGROUND

Epidemiological studies suggest strong association of lung disorders with occupational exposure to asbestos, silicon and arsenic. The chronic occupational exposure primarily through inhalation results in adverse outcome on the respiratory tract which may also be fatal. Although several mechanisms have attributed towards these diseases; the molecular pathogenesis is still unknown.

OBJECTIVE

In this review, we investigated the plausible molecular mechanism based on current research that may identify the genetic and epigenetic susceptibility of respiratory disorders upon such occupational exposures in humans.

METHODS

We considered genetic variants and epigenetic alterations associated with pulmonary exposure hazards leading to asbestosis, silicosis and arsenicosis. Our review is stringently based on the literatures available through peer-reviewed articles mostly published in the last 10 years. Relevant search were conducted using keywords like "occupational lung disorders" along with "asbestos", "silicon" and "arsenic".

RESULTS

Till September 2015, pubmed search yielded approximately 780 articles relating to asbestos exposure; 240 articles for silicon exposure and 60 articles for arsenic exposure. Extensive screening for genetic and epigenetic factors identified certain genes and related pathways that are important to determine the susceptibility of an individual towards such occupational exposure.

CONCLUSION

The link between genotype and phenotype and its association with disease susceptibility is very complex in nature due to several factors like person's environment, lifestyle and nutritional status. The epigenome is dynamic as well as reversible and can be reshaped further by certain dietary components throughout its life. In the present review, we have addressed the role of molecular pathogenesis of occupational lung diseases based on the genetic variability and epigenetic alterations and also attempted to highlight the promising aspect of dietary interventions to counter toxic outcomes upon occupational exposure to asbestos, silicon or arsenic.

Association of TNFα-308, IFNγ+874, and IL10-1082 gene polymorphisms and the risk of non-small cell lung cancer in the population of the South Indian state of Telangana

BACKGROUND

Cytokine-mediated inflammation is important in the pathogenesis of non-small cell lung cancer (NSCLC). Genetic polymorphisms in cytokine genes and their association with lung cancer in the Indian population have not been reported.

METHODS

For the first time, we analyzed genetic polymorphisms of TNFα ^-308, IFNγ ⁺⁸⁷⁴, and IL10 ^-1082 genes in 246 NSCLC patients and 250 healthy controls in the South Indian population from Telangana using ARMS PCR.

RESULTS

IFNγ⁺⁸⁷⁴ A/T and IL10^-1082 G/G gene polymorphisms were found to be significantly associated with NSCLC with 1.56- and 1.68-fold disease risk, respectively. There was no association between the risk of NSCLC and TNFα^-308 polymorphism. Gene polymorphisms stratified according to smoking revealed that IFNγ⁺⁸⁷⁴ A/T polymorphisms in smokers increased the disease risk by 2.91 fold. IL10^-1082 G/G polymorphisms showed 2-fold increased risk among patients who were smokers when compared to the controls. However, there was no association between TNFα^-308, IFNγ⁺⁸⁷⁴, and IL10^-1082 gene polymorphism and the stage of the NSCLC patients. The overall risk associated with the combination of these polymorphisms indicated that the TNFα^-308 G/A + IFNγ⁺⁸⁷⁴ A/T + IL10^-1082 G/G genotype increased the risk by 1.5 fold.

CONCLUSIONS

The results of our study indicate an association between cytokine gene polymorphisms and the risk of NSCLC in an Indian population.