A. V. Pereira

Salivary Proteome and Peptidome Profiling in Type 1 Diabetes Mellitus Using a Quantitative Approach

In the present study, we applied iTRAQ-based quantitative approach to explore the salivary proteome and peptidome profile in selected subjects with type 1 diabetes, with and without microvascular complications, aiming to identify disease-related markers. From a total of 434 distinct proteins, bactericidal/permeability-increasing protein-like 1 and pancreatic adenocarcinoma up-regulated factor were found in higher levels in the saliva of all patients while increased content of other proteins like alpha-2-macroglobulin, defensin alpha 3 neutrophil-specific, leukocyte elastase inhibitor, matrix metalloproteinase-9, neutrophil elastase, plastin-2, protein S100-A8 and protein S100-A9 were related with microvascular complications as retinopathy and nephropathy. Protein-protein interaction network analysis suggests the functional clusters defense, inflammation and response to wounding as the most significantly associated with type 1 diabetes pathogenesis. Peptidome data not only support a diabetes-related higher susceptibility of salivary proteins to proteolysis (mainly of aPRP, bPRP1 and bPRP2), but also evidenced an increased content of some specific protein fragments known to be related with bacterial attachment and the accumulation of phosphopeptides involved in tooth protection. Overall, the salivary protein and peptide profile highlights the importance of the innate immune system in the pathogenesis of type 1 diabetes mellitus and related complications. This study provides an integrated perspective of salivary proteome and peptidome that should be further explored in future studies targeting specific disease markers.

Protease profiling of different biofluids in type 1 diabetes mellitus

OBJECTIVES We aimed to disclose the proteolytic events underlying type 1 diabetes and related complication through protease profiling in the bodily fluids serum, urine and saliva. DESIGN AND METHODS Zymography followed by LC-MS/MS was performed for protease identification and quantitative comparison of proteolytic activity between healthy, type 1 diabetic patients with no complications and with retinopathy and nephropathy. Western blotting was also accomplished for MMP-9 and MMP-2 identification and expression analysis. RESULTS Only MMP-2 and MMP-9 were observed in serum with significantly increased levels and activity observed in diabetic patients. In urine and saliva other proteases besides MMPs were identified by MS and presented disease-dependent activity variations. Among these are complex MMP-9/Neutrophil gelatinase-associated lipocalin, aminopeptidase N, azurocidin and kallikrein 1 with more activity noticed in type 1 diabetes patients with nephropathy and/or retinopathy. CONCLUSION Our data highlight the usefulness of urine and saliva for the monitoring of type-1 diabetes-related proteolytic events, where aminopeptidase N, azurocidin and kallikrein 1 appear as promising screening targets for type 1 diabetes-related complications.