Abstract
Background: α, α-Trehalase, located on renal proximal tubules, is a glycoprotein which hydrolyses α, α-trehalose to two glucose molecules. Urinary trehalase reflects a renal proximal tubular damage, but its activity has not been routinely measured because of the following two reasons: (1) measurement of the activity is rather complicated, and (2) conventional assays for enzyme activity might not always reflect the whole trehalase protein, because inactivation of the enzyme may occur in various urinary samples. We therefore have developed a new ELISA for quantification of urinary trehalase and tried to assess the extent of renal tubular damages.
Methods: We have established novel monoclonal antibodies for human trehalase and a sandwich ELISA for quantification of urinary trehalase. Moreover, we have assessed the urinary trehalase level by two methods, i.e. the trehalase quantity by this ELISA and the trehalase activity by a conventional assay. The results of these two methods were compared.
Results: The ELISA system was more sensitive than the detection of enzyme activity and could detect a subtle difference of trehalase quantity in renal diseases. Highly significant increases in both quantity and activity were seen in patients with nephrotic syndrome (acute phase), Lowe syndrome, and Dent disease. Especially, their enzyme quantity was 200∼260 fold higher than that of the control subjects. The extent of trehalase quantities in chronic glomerulonephritis was larger than the elevation of their enzyme activities compared to the control group. In a patient with acute renal failure, trehalase quantity was 27-fold than the control and yet trehalase activity was similar to control.
Conclusions: We have established an ELISA system for quantification of urinary trehalase by using novel monoclonal antibodies. Our ELISA system was simpler and sensitive than a conventional activity assay and reflects a whole trehalase protein. This ELISA can be useful as a common tool for clinical assessment of renal proximal tubular damage.
