Environmental pollution by carbon particles emitted by car exhaust, smoking and long term inhalation of dust of various origins cause chronic inflammation of the lungs and has link to rheumatoid arthritis. Similarly nanomaterials are reported to have health and safety implications for the manufacture, use and ultimate disposal of nanotechnology products and materials.

Exposure to nanoparticles is found to have a serious impact on health and link to rheumatoid arthritis and the development of other serious autoimmune diseases. Nanotechnology products which if not handled appropriately may contribute to the generation of airborne pollutants causing risks to health.
Research
Researchers at Trinity College Dublin's School of Medicine have investigated whether there is a common underlying mechanism contributing to the development of autoimmune diseases in human cells due to the exposure nanoparticles.
The researchers applied nanomaterials such as ultra fine carbon black, carbon nanotubes and silicon dioxide particles of different sizes to human cells derived from the lining of the airway passages, and to the cells that are most frequently exposed to the inhaled foreign particles and in mice exposed to chronic inhalation of air contaminated with single walled carbon nanotubes.
Findings
They found that all types of nanoparticles were causing an identical response in human cells and in the lungs of mice, resulting in specific transformation of the amino acid arginine into the molecule called citrulline which can lead to the development of autoimmune conditions such as rheumatoid arthritis.
In the transformation to citrulline, human proteins which incorporate this modified amino acid as building blocks, can no longer function properly and are subject to destruction and elimination by the bodily defense system. Once programmed to get rid of citrullinated proteins, the immune system can start attacking its own tissues and organs, thereby causing the autoimmune processes which may result in rheumatoid arthritis.
Applications
The research establishes a clear link between autoimmune diseases and nanoparticles. Preventing or interfering with the resulting citrullination process looks therefore as a promising target for the development of future preventative and therapeutic approaches in rheumatoid arthritis and possibly other autoimmune conditions.