Background: Silicosis is characterized by fibrosing nodular lesions that eventually develop into progressive pulmonary fibrosis. Pro-inflammatory cytokines, such as interleukin-1 (IL-1), play a key role in the development of silicosis by regulating mediators which are responsible for lung injury, inflammation, and potentially fibrosis. To study whether functional single nucleotide polymorphisms (SNPs) located in the regulatory elements of genes coding for the IL-1alpha, IL-1beta, and IL-1 receptor antagonist (RA) cytokines are associated with silicosis, we examined 318 Caucasian cases confirmed histopathologically with pulmonary silicosis and 163 controls without any apparent inflammation or other pulmonary disease.
Methods: Genotyping was carried out by polymerase chain reaction-restriction fragment length polymorphism technique.
Results: The proportion of the IL-1RA (+ 2018) allele 2 genotype was increased in miners with silicosis (0.27) compared to controls (0.16). The odds of being a case were 2.15 (CI = 1.4-3.3) times higher for subjects with at least one copy of allele 2. No statistically significant differences in the allelic frequencies or genotype distributions for IL-1alpha (+ 4845) or IL-1beta (+ 3953) were found between the control and disease groups.
Conclusions: This is the first report showing an association between the IL-1RA (+ 2018) polymorphism and silicosis, and suggests that this polymorphism may confer increased risk for the development of the disease.