The identification of tyrosine-nitrated human serum albumin in airborne particulate matter from Japan

Atomospheric particulate matter (PM) has been accepted as a risk to human health worldwide. PM contains a variety of components, but it is not clear which components are harmful to human health. For example, there have been many reports on metals, but there have been only a few studies on proteins. Based on an analysis of serum antibodies in a mouse model of PM-induced asthma reported previously, we have been conducting research focusing on the proteins contained in PM. In the present study, we found for the first time that human serum albumin (HSA) is bound to PM. HSA was detected in total suspended particulate matter (TSP) and PM2.5, from various regions in Japan, during all seasons. The presence of HSA in PM was confirmed by proteomics analysis, amino acid analysis, immunoblotting and BD140, which emits fluorescence when bound to a specific HSA site. Moreover, we discovered that TSP-binding HSA was tyrosine-nitrated, one of a chemical modification via environmental atmospheric pollutants using high performance liquid chromatography-electrochemical detection. It was concluded that although the origin of HSA in PM was unclear, HSA is present in the airborne PM of Japan, partially modified for tyrosine nitration.

Automated summary

Atmospheric particulate matter has been recognized as a global health risk, with studies focusing on identifying harmful components. This study found human serum albumin (HSA) bound to PM in Japan, with evidence of tyrosine nitration, a chemical modification from environmental pollutants. HSA was detected in various PM samples, indicating its presence in airborne particles.