Serum Prolidase Activity and its Association with Oxidative Stress and Inflammation in Silicosis

Background: Prolidase is reported to be a useful biomarker for the detection and monitoring of fibrosis-related diseases. This study aimed to investigate the potential prognostic value of serum prolidase activity in silicosis and its relationship between oxidative stress and inflammatory parameters. Methods: A total of 236 participants were studied, out of which 113 were patients with silicosis, 70 silica-exposed workers without the disease and 53 age- and sex-matched healthy volunteers. Serum levels of prolidase, parameters of oxidative stress which were superoxide dismutase, catalase, 8-hydroxy-2-deoxyguanosine, glutathione peroxidase, glutathione reductase, and that of inflammation which included tumor necrosis factor-α, fibroblast growth factor (FGF), interferon-gamma (IFN-γ), and interleukins interleukin-1 alpha and interleukin-1 beta were determined using commercial Elisa kits and spectrophotometric measurements. Results: All the participants were male, with a mean ± standard deviation of age of 41.61 ± 7.1 years in the silicosis group, 38.0 ± 7.12 years in the silica-exposed group without disease, and 41.66 ± 9.9 years in the healthy control group. Serum prolidase activity was higher in the silicosis and exposure groups than in healthy controls, although the difference was not statistically significant (P = 0.55). Superoxide dismutase and glutathione peroxidase levels were significantly lower (P < 0.001) in the exposure and silicosis groups, while 8-hydroxy-2-deoxyguanosine, tumor necrosis factor-alpha, FGF, IFN-γ, and interleukin-1 alpha levels were significantly elevated (P < 0.001). In individuals with high prolidase activity, both oxidative stress and inflammation parameters were high. Conclusion: Elevated prolidase activity, along with increased oxidative stress and inflammatory markers in silica-exposed individuals and silicosis from the study, suggests a potential role of prolidase in the pathogenesis of silicosis. These findings may contribute to understanding the molecular mechanisms underlying silica-induced lung injury, though further research is needed to establish its prognostic utility.