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Alzheimer's disease (AD) is a progressive form of dementia characterized by increased production of amyloid-β plaques and hyperphosphorylated tau protein, mitochondrial dysfunction, elevated oxidative stress (OS), reduced protein clearance among others. Several studies showed systemic modifications of immune and inflammatory systems due, in part, to decreased levels of T cells in peripheral blood during AD. Considering that oxidative stress, both in the brain and in the periphery, can influence the activation and differentiation of T cells, we investigated the nitro-oxidized proteome of blood T cells derived from AD patients compared to non-demented subjects (NSD) by using a redox proteomic approach. We identified eleven proteins showing increasing levels of 3-nitrotyrosine (3-NT) in AD T cells compared with NSD. These proteins are involved in energy metabolism, transcriptional regulation and antioxidant response and can help to clarify molecular mechanism that impact on the reduced T cells differentiation in AD. Our results highlight the role of peripheral OS in T cells related to immune-senescence during AD pathology focusing on the specific target of protein nitration that can be suitable to further therapies.

In the present study, we show that the heterogeneous mixture of glycoforms of the basic salivary proline-rich protein 3M, encoded by PRB3-M locus, is a major component of the acidic soluble fraction of human whole saliva in the first years of life. Reversed-phase high-performance liquid chromatography with high-resolution electrospray ionization mass spectrometry analysis of the intact proteoforms before and after N-deglycosylation with Peptide-N-Glycosidase F and tandem mass spectrometry sequencing of peptides obtained after Endoproteinase GluC digestion allowed the structural characterization of the peptide backbone and identification of N- and O-glycosylation sites. The heterogeneous mixture of the proteoforms derives from the combination of 8 different neutral and sialylated glycans O-linked to Threonine 50, and 33 different glycans N-linked to Asparagine residues at positions 66, 87, 108, 129, 150, 171, 192, and 213.

The combination of top-down and bottom-up platforms was utilized for the LC-MS proteomic characterization of the intracystic fluid of adamantinomatous craniopharyngioma pediatric brain tumor disease. Proteins and peptides characterization was achieved by high-resolution LC-ESI-LTQ-Orbitrap-MS analysis while low-resolution LC-ESI-IT-MS was applied for the complete screening of the samples and the evaluation of the protein distribution within patients. Top-down analyses were applied to liquid/liquid extracted samples while bottom-up analyses were performed after trypsin digestion of both untreated and pretreated samples. The two proteomic approaches were complementary for the characterization of the proteome of craniopharyngioma intracystic fluid. Proteins and peptides involved in inflammation, mineralization processes and lipid transport were identified, in agreement with the calcium flecks, cholesterol granules and bone residues characteristic of this fluid. Apolipoprotein A-I, A-II, C-I and J, hemoglobin fragments, ubiquitin, α-2-HS-glycoprotein or fetuin A, α-1-antichymotrypsin, vitamin D binding protein, and α-1-acid glycoprotein were characterized. These data could be relevant for the comprehension of the processes involved in the pathogenesis of the disease and the development of the cyst and could contribute to the individuation of therapeutic targets for the reduction of the cyst volume delaying and/or avoiding invasive surgical treatments.

SUMMARY The use of human saliva as a diagnostic and prognostic fluid has until recently been somewhat disregarded. Although sample collection is non-invasive, physiological and genetic variations were largely responsible for its infrequent application in the past. Recently, several proteomic studies contributed to partial elucidation of the salivary proteome (more than 2400 protein components have been characterized), both in terms of composition, contributions to whole saliva and genetic/physiological variability. On this basis, is not too optimistic to believe that in the near future human saliva could become a relevant diagnostic fluid. In this review, the characterization by proteomic approaches of new salivary markers in oncology, head and neck carcinoma (oral cavity, oropharynx, larynx, and salivary glands), breast and gastric cancers, salivary gland function and disease, Sjögren syndrome, systemic sclerosis, dental and gingival pathology, systemic, psychiatric and neurological diseases, is described.