RP-HPLC-ESI-IT Mass Spectrometry Reveals Significant Variations of the Human Salivary Protein Profile Associated with Predominantly Antibody Deficiencies

Abstract

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Top-Down Proteomics of Human Saliva Highlights Anti-inflammatory, Antioxidant, and Antimicrobial Defense Responses in Alzheimer Disease

“…Thirty microliters of acidic extracts were injected in HPLC/low-resolution ESI-MS, applying procedures and conditions optimized in our previous studies ( Contini et al, 2020 ; Serrao et al, 2020 ). The total ion current (TIC) chromatographic profiles were analyzed to selectively search and quantify the peptides/proteins reported in Supplementary Table 2 ( Supplementary Material ), which shows UniProtKB codes, elution times, and experimental and theoretical average mass values (Mav) of the proteins/peptides included in the study.…”

“…The estimated percentage error of the XIC analysis was <8%. Eventual dilution errors occurring during sample collection were corrected by normalizing XIC peak areas of peptides/proteins with the XIC peak area of leu-enkephalin used as internal standard, as described in a previous study ( Contini et al, 2020 ). Then, the corrected XIC peak area values of each peptide/protein were normalized on the TPC of each sample.…”

Salivary Proteome Changes in Response to Acute Psychological Stress Due to an Oral Exam Simulation in University Students: Effect of an Olfactory Stimulus

“…From a functional point of view, CSTB has been associated to the macrophage activation, apoptosis prevention [ 54 ], regulation of cell cycle entry [ 55 ], protection against oxidative stress of mitochondria [ 56 ] and neurons [ 57 ] due to its neuroprotective role, and it is considered part of the innate immunity system. However, to date, the exact function of salivary CSTB is still unclear [ 58 ].…”

Stabilization of Salivary Biomarkers

“…112 This treatment is an ideal preprocessing step to evaluate salivary proteomic content via certain analytical methods (e.g., high-performance liquid chromatography− electrospray ionization-mass spectroscopy), but it may be limited to the analysis of proteins and peptides soluble in acidic solutions. 113 Moreover, adding acidic buffers to salivary samples can cause the coprecipitation of other proteins 114,115 and may interfere with certain analytical techniques. Snap-freezing remains the gold standard for the preservation of highly unstable salivary proteins since even slow freezing could provoke instability and promote protein-induced aggregation and precipitation.…”

“…Acidic buffers also inhibit protease activity and induce a decrease in sample viscosity, facilitating analyte quantification . This treatment is an ideal preprocessing step to evaluate salivary proteomic content via certain analytical methods (e.g., high-performance liquid chromatography–electrospray ionization-mass spectroscopy), but it may be limited to the analysis of proteins and peptides soluble in acidic solutions . Moreover, adding acidic buffers to salivary samples can cause the coprecipitation of other proteins , and may interfere with certain analytical techniques.…”