August 2018:
In the past decades, evidence from several reports has shown that environmental agents can act as potential triggers for SSc. One of these is exposure to silica — a mixture of the natural chemical silicon with two oxygen atoms (dioxide) — which is naturally found in rocks, sand and clay and in materials such as bricks and concrete.
Inhalation of silica-containing dust has been linked to autoimmune diseases in genetically predisposed individuals, including SSc. Research with humans and animal models suggests that silica exposure triggers multiple changes in the immune system, such as the production of signaling molecules (cytokines) that promote inflammation and scarring (fibrotic) lesions.
In this study, researchers analyzed blood samples for traces of silica microparticles and nanoparticles, as well as silicon, in 80 SSc patients, including 70 females, at a mean age of 58.4, who lived in the Italian province of Modena, which has a high density of industries with high risk of silica dust exposure. The same analysis was performed on 50 sex-matched healthy controls from the same geographical area.
Additional elements screened in the analysis included aluminium, chromium, copper, iron, magnesium, manganese, titanium, and zinc.
Participants’ possible exposure to microparticles and nanoparticles was determined via a questionnaire focusing on their occupational exposure, environmental exposure, smoking habits, and prosthesis implants.
Of the 80 SSc patients, 43 (54%) were exposed to microparticles and nanoparticles, as well as six of the controls (12%), mainly due to work in the ceramic industries.
Other exposure categories — environmental exposure, smoking habits, and prosthesis implants — were much rarer in both groups.
Exposure to silica dust preceded disease onset, with a median exposure duration of 16.4 years, and 21 of the 43 SSc patients were still exposed to the harmful particles at the time of the study.
In these 21 patients, the levels of silicon were significantly higher than in the remaining 22 patients who had been exposed in the past.