Predictive value of novel biomarkers for chronic kidney disease among workers occupationally exposed to silica.

There is a pressing need to find reliable biomarkers for the early diagnosis of silica-induced nephropathy. Abundant genes are upregulated in damaged kidneys with subsequent protein products appearing in the urine. Liver-type fatty acid-binding protein (L-FABP) and kidney injury molecule-1 (KIM-1) are among the most promising. Our objective was to study the importance of L-FABP and KIM-1 genes and their urinary proteins in the early detection of silica-induced renal injury, as compared with other conventional biomarkers. A cross-sectional study was conducted among 90 pottery workers occupationally exposed to silica, as compared to 90 controls. A full history taking and complete clinical examination were performed. Levels of serum creatinine, liver enzymes, urinary silicon, KIM-1, and L-FABP gene expression and protein products were measured. Estimated glomerular filtration rate (eGFR) was calculated, and abdominal ultrasound was performed. The results showed that the silica-exposed group had a statistically significant increase in serum creatinine and urinary silica, as well as a significant decrease in eGFR. Additionally, a significant increase in KIM-1 and L-FABP gene expression, associated with a significant increase in their urinary protein, was found among the exposed group. A positive correlation between urinary silica level and L-FABP gene expression was also found. A receiver operating characteristic curve analysis for L-FABP and KIM-1 gene as predictors for silica-induced nephropathy showed that L-FABP gene and protein specificity were greater than the KIM-1 gene and protein. Taken together, these findings suggest that the L-FABP gene and its protein product may be used as early indicators for renal injury among silica exposed workers.