Autoimmune diseases, the role of pollution
Air pollution could play an important role in the development of autoimmune diseases, such as rheumatoid arthritis.
These were the conclusions of a study led by Sapienza University of Rome, recently published in the journal Cell Death & Disease.
Coordinated by Guido Valesini from the Department of Internal Medicine and Medical Specialties at Sapienza University, the study was carried out in collaboration with Silvana Fiorito and researchers at the Institute of Translational Pharmacology (IFT) of the National Research Council (CNR).
The researchers evaluated the effects of atmospheric particulate matter produced by the combustion of gases in Euro 4 and Euro 5 diesel engines on the functionality and biological characteristics of bronchial cell tissues.
“It is interesting to underline that Euro 5 particulate matter was found to be potentially more harmful than that produced by Euro 4 engines. This fact shows that a reduction in the amount of particulate matter emissions does not automatically translate into a reduction in toxic effects”, said Guido Valesini.
Tests conducted by the researchers showed that carbon nanoparticles produced by the combustion of diesel engines can induce autophagy, a form of self-digestion, and death of cells in the bronchial epithelium, with associated production of “citrullinated” proteins.
“Citrullination” – a physiological process that normally regulates protein functions – becomes excessive in patients with rheumatoid arthritis. In these cases, the body responds to the pathological accumulation of citrullinated proteins by producing antibodies, leading to an autoimmune attack against normal tissues.
“On the basis of our observations, we can hypothesize that atmospheric pollution may play a non-secondary role, in susceptible subjects and through complex mechanisms, in the pathogenesis of some immune-mediated diseases, such as rheumatoid arthritis”, added Valesini.
In fact, the correlation between increased citrullination levels and an increased risk of developing rheumatoid arthritis was already known, to the point that the tests used to diagnose this disease highlight the presence of antibodies directed against citrullinated proteins.
The main cause of the disease is yet to be established but there is increasing evidence of the role that environmental factors may play as a contributory cause.