Higher levels of cathepsin D were independently associated with diabetes mellitus, renal failure and higher levels of interleukin-6 and N-terminal pro-B-type natriuretic peptide (P < 0.001 for all).
Cathepsin D improved the prediction of dysglycaemia, which may be helpful in the a priori risk determination of diabetes as a motivation for confirmatory OGTT.
Four proteins (Scavenger receptor cysteine rich type 1 protein M130, Fatty acid binding protein 4, Plasminogen activator inhibitor 1 and Insulin-like growth factor-binding protein 2) with a previously established association with incident diabetes and 3 proteins (Cathepsin D, Galectin-4, Paraoxonase type 3) with a novel association with incident diabetes.
In contrast to its low and uniform distribution in the tubular epithelium in normal kidney tissues, CatD demonstrated flecked and increased expression in tubules with relatively integral structures, and disappeared in disordered tubules in DM kidney tissues.
In conclusion, we show for the first time: a) presence of a novel truncated ApoA-I form, ApoA-IΔ(1-38), in human serum; b) ApoA-IΔ(1-38) is transported by LDL; c) ApoA-IΔ(1-38) is increased in dense LDL fractions of DM patients; and d) cathepsin D-ApoA-I truncation may lead to ApoA-IΔ(1-38) binding to LDLs, increasing their susceptibility to oxidation and contributing to the high cardiovascular risk of DM patients.