Increased Serum Heme Oxygenase-1 in Silicosis-Suspected Subjects from Limestone Crusher Factories

Abstract

Heme Oxygenase-1 (HO-1) is a lung inflammation and oxidative stress biomarker. In this study, it was proposed as a sensitive biomarker to indicate silicosis. The objective of the study was to determine a relationship between serum HO-1 and occupational exposure to silica in limestone crusher workers. Total crystalline silica was quantified by ultraviolet visible spectrometry. A chest radiograph was performed in a General Hospital by a trained radiologist. The serum HO-1 level was determined by sandwich enzyme immunoassay. In the results, the total crystalline silica in the studied factories, ranged from 0.94-27.03 mg/m³. The level of serum HO-1 in silica high exposure group was significantly elevated compared with low exposure group. In chest radiography, there were 4 silicosis-suspected subjects and their serum HO-1 levels were significantly higher than non-silicosis subjects after adjustment by mean age and smoking status. A positive relationship between serum HO-1 level and increased employment duration was also observed. The increased serum HO-1 level was specifically related to silica exposure and chest radiograph finding independently from age and smoking status. The serum HO-1 level has a potential to be used as an indicator of silicosis and it could also reflect the oxidative stress caused by silica exposure.