Urinary leucine aminopeptidase 3 in population environmentally exposed to airborne arsenic

Environmental arsenic contamination is a major toxicological problem worldwide due to its carcinogenic and nephrotoxic potential.

The purpose of this observational study was to determine the suspected association between urinary arsenic (uAs) and urinary leucine (or leucyl) aminopeptidase 3 (uLAP₃) to evaluate uLAP₃ as a candidate biomarker of exposure to airborne arsenic.

A total of 918 adults occupationally and/or environmentally exposed to airborne arsenic were enrolled in the study. Baseline information (age; sex; history of smoking; alcohol, fish and seafood consumption) was gathered. Total uAs concentrations [μg/L] of 918 subjects, as well as the sum of arsenic species (ΣiAs) in 259 subjects, were obtained. Urinary LAP₃ was measured by an immune-enzymatic assay using an ELISA kit. Urinary creatinine concentration was assessed with the IB/lAB/1289 research protocol (version II, 2015-09-17). The values of uAs and uLAP₃ were recalculated per unit of creatinine. The association between uAs and uLAP₃ was assessed using a logistic regression model adjusted for confounders.

The study identified a positive correlation between the logarithm of uAs and the logarithm of uLAP₃ in the study population (r = 0.1737, p < 0.0000) and between urinary creatinine and uLAP₃ concentration not adjusted for creatinine level (r = 0.1871, p < 0.001). In the logistic regression model, there was also an association between increased (≥15 µg/L) uAs and decreased (below the 25th quartile) uLAP₃ [OR uLAP₃ = 1.22 (95% CI 1.03 to 1.44, p < 0.02)].

These data suggest that urinary LAP₃ may be a potential biomarker of arsenic exposure, which warrants further study.