Saliva contains a complex mixture of proteins and peptides as well as fragments derived from these molecules. By RP 1 -HPLC-ESI-MS analysis of the acidic soluble fraction of human whole saliva we have identified in the chromatographic pattern more than 120 different proteins and naturally occurring peptides (1-6). Their characterization was performed by a variety of mass spectrometric techniques coupled with different enzymatic treatments and amino acid sequencing. The proteins and naturally occurring peptides belong to families of well characterized salivary proteins including Histatins, Statherin, acidic and basic proline-rich proteins (aPRP and bPRP), Cystatins, and Defensins (1-6). Two-dimensional gel electrophoresis has also been used by other researchers for analysis of salivary proteins and peptides, but this technique is not well suited for identification of small peptides as illustrated by the difficulty in identifying Histatins and the majority of bPRPs and bPRP fragments (7-9). However, knowledge of salivary proteins and peptides as well as their naturally occurFrom the ‡Dipartimento di Scienze Applicate ai Biosistemi, Università di Cagliari,

The acidic-soluble protein content of human gingival crevicular fluid was analyzed by reverse-phase high-performance liquid chromatography (RP-HPLC), and the eluent deriving from the chromatography separation was directly introduced into an ion-trap mass spectrometer through electrospray ionization (ESI-IT MS). By this technique the molecular weight of peptides/proteins was determined with a precision of approximately 1/10,000 amu. On the basis of the chromatographic behavior and the knowledge of the molecular mass value, some peptides and proteins soluble in acidic solution were unambiguously recognized. Besides high quantities of human serum albumin, alpha-defensins 1-4 and minor amounts of cystatin A, statherin, basic PB salivary peptide and other unidentified components were detected. The presence of alpha-defensins in gingival crevicular fluid is in agreement with their relevant contribution to protein composition deriving from granulocyte secretions. Other peptides and proteins abundant in human saliva, such as proline-rich proteins (PRPs) and histatins, were not detected in gingival crevicular fluid. Further investigations will be necessary to establish the origin of statherin and PB salivary peptide in gingival crevicular fluid.

Saliva is a body fluid of a unique composition devoted to protect the mouth cavity and the digestive tract. Our high performance liquid chromatography (HPLC)-electrospray ionization-MS analysis of the acidic soluble fraction of saliva from preterm human newborn surprisingly revealed more than 40 protein masses often undetected in adult saliva. We were able to identify the following proteins: stefin A and stefin B, S100A7 (two isoforms), S100A8, S100A9 (four isoforms), S100A11, S100A12, small proline-rich protein 3 (two isoforms), lysozyme C, thymosins ␤ 4 and ␤ 10 , antileukoproteinase, histone H1c, and ␣ and ␥ globins. The average mass value reported in international data banks was often incongruent with our experimental results mostly because of post-translational modifications of the proteins, e.g. acetylation of the N-terminal residue. A quantitative label-free MS analysis showed protein levels altered in relation to the postconceptional age and suggested coordinate and hierarchical functions for these proteins during development. In summary, this study shows for the first time that analysis of these proteins in saliva of preterm newborns might represent a noninvasive way to obtain precious information of the molecular mechanisms of development of human fetal oral structures. Molecular & Cellular Proteomics 10: 10.1074/mcp.M110.003467, 1-14, 2011.Saliva is a body fluid of a very complex and specific composition devoted to the protection and well-being of the oral cavity and, because it is swallowed, of the digestive tract (1). Protection is ensured by organic and inorganic solutes and specific peptides and proteins, such as acidic and basic proline-rich proteins, ␣-amylases, salivary cystatins, histatins, and statherin (2-5). In a previous study (6), we have established that some salivary proteins and peptides reach the levels typically observed in the adult around 18 years of age. Encouraged by the noninvasive specimen collection, we explored the salivary protein composition of at-term and preterm newborns, in order to establish the starting point of the secretion of the proteins and peptides specific of saliva. Our first study (7) showed that acidic proline-rich proteins secretion started, although at very low levels, at 7 months of postconceptional age. At this age the level of phosphorylation of these proteins was low and it increased reaching a value comparable with that of adults at about one year of age, in concomitance with the beginning of deciduous dentition. Other deep differences between human and preterm saliva were however evident. Highly abundant protein masses detected in preterm saliva were undetectable (at the sensitivity level of our MS apparatus) or at very low level in adult saliva. In a previous study (8) we identified, by different MS approaches, thymosin ␤ 4 (T␤ 4 ) and thymosin ␤ 10 (T␤ 10 ) in preterm newborn saliva and established by immunohistochemistry their presence in fetal salivary glands. This finding let us to suppose that in preterm newborns these peptides derived from glan...

Proteomic platforms can be classified in bottom-up strategies, which analyze the sample after proteolytic digestion, and top-down strategies, which analyze the intact naturally occurring proteome. Bottom-up platforms are high-throughput because they can investigate a large number of proteins, regardless of their dimension. Nonetheless, information on post-translational modifications (PTMs) can be lost, especially those regarding naturally occurring cleavages and alternative splicing. Top-down platforms cannot cover vast proteomes, however, they can disclose subtle structural variations occurring during protein maturation and allow label-free relative quantifications in an unlimited number of samples. A repertoire of 256 masses belonging to naturally occurring proteins and peptides consistently detected by RP-HPLC-ESI-MS analysis of the acidic soluble fraction of human whole saliva is presented in this study. Of them, 233 have been identified, while 23 are still pending for the definitive characterization. The present review reports average and mono-isotopic masses of the peptides and proteins detected, RP-HPLC elution times, PTMs, origin and quali-quantitative variations observed in several physiological and pathological conditions. The information reported can be a reference for users of top-down RP-HPLC-ESI-MS proteomic platforms applied to the study of the human salivary proteome as well as of other human bodily fluids.

Thymosin beta(4) (Tbeta(4)), its sulfoxide, and thymosin beta(10 )(Tbeta(10)) were detected in human saliva and identified by different strategies based on RP HPLC coupled to electrospray multidimensional IT MS. Tbeta(4 )was almost always detected in whole saliva, its sulfoxide sporadically, Tbeta(10) rarely. Tbeta(4) was undetectable in parotid saliva and less concentrated in submandibular/sublingual saliva than in whole saliva. Analysis of gingival crevicular fluid revealed high relative amounts of Tbeta(4), Tbeta(4) sulfoxide, and Tbeta(10) in all the samples. Tbeta(4) mean concentration was 200 times higher in crevicular fluid (20 micromol/L, N = 9) than in whole saliva (0.1 micromol/L, N = 9). Crevicular fluid concentration of Tbeta(4 )(ca. 5% represented by its sulfoxide) and beta(10 )significantly correlated (r = 0.856; N = 9), and their ratio was about 5. A significant correlation was also observed between Tbeta(4 )concentrations in whole saliva and gingival crevicular fluid (r = 0.738; N = 9). Immunohistochemical analysis of the major salivary glands showed that immunoreactivity for Tbeta(4) is restricted to ductal cells, with minor degree of focal positivity in some acinar cells. On the whole, results indicate that gingival sulcus is a main, although not the sole, source for oral Tbeta(4 )and Tbeta(10).

Physiological variability of the naturally occurring, human salivary secretory peptidome was studied as a function of age. The qualitative and quantitative changes occurring in the secretion of proteins/peptides specific to the oral cavity (i.e., basic salivary proline-rich proteins, salivary acidic proline-rich phosphoproteins, statherin, proline-rich peptide P-B, salivary cystatins, and histatins) were investigated by high-performance liquid chromatography-electrospray ionization-mass spectrometry in 67 subjects aged between 3 and 44 years. Subjects were divided into five age groups: group A, 8 donors, 3-5 years; group B, 11 donors, 6-9 years; group C, 20 donors, 10-12 years; group D, 15 donors, 13-17 years; group E, 13 donors, 24-44 years. Basic salivary proline-rich proteins, almost undetectable in the 3-5 and 6-9 years groups, reached salivary levels comparable to that of adults (24-44 years) around puberty. Levels of peptide P-D, basic peptide P-F, peptide P-H, peptide P-J (a new basic salivary proline-rich protein characterized in this study), and basic proline-rich peptide IB-1 were significantly higher in the 10-12-year-old group than in the 3-5-year-old group, whereas the increase of proline-rich peptide II-2 was significant only after the age of 12 years. The concentration of salivary acidic proline-rich phosphoproteins, histatin-3 1/24, histatin-3 1/25, and monophosphorylated and diphosphorylated cystatin S showed a minimum in the 6-9-year-old group. Finally, the histatin-1 concentration was significantly higher in the youngest subjects (3-5 years) than in the other groups.

BackgroundMood and anxiety symptoms in chronic hepatitis C (CHC) may be related to the patient awareness of the diagnosis and prognosis, to side effects induced by interferon (IFN)-alpha treatment, as well as to substance abuse. However, the observation of metabolic alterations in patients with CHC has led to hypothesize a direct effect of hepatitis C virus (HCV) on brain function. This study was aimed at elucidating whether CHC is associated with specific anxiety or mood disorders independently of confounding factors.MethodsPatient cohort: consecutive patients, 135 with CHC and 76 with chronic hepatitis B (CHB). Exclusion criteria: previous treatment with IFN-alpha, co-infection with HCV and hepatitis B virus, infection with human immunodeficiency virus, drug or alcohol abuse, or malignancies. Controls: subjects without evidence of hepatitis randomly extracted from the database of a previous epidemiological study; they were divided into two groups of 540 (332 males) and 304 (220 males) as controls for patients with CHC and CHB, respectively. The psychiatric diagnosis was formulated by means of the Composite International Diagnostic Interview Simplified carried out by a physician according to DSM-IV criteria.ResultsA higher lifetime prevalence of major depressive disorder (MDD) was observed among CHC compared to CHB or controls. The risk of MDD was not statistically different between CHB and controls. Both the CHC and CHB groups showed a significantly higher frequency of panic disorder when compared to controls. No statistical differences were observed in the prevalence of general anxiety disorder and social phobia when CHC or CHB were compared to controls.ConclusionThe present study provides the first evidence of an association between CHC and MDD, diagnosed on the basis of well-defined international criteria. This association is independent of treatment with IFN-alpha and is not influenced by substance or alcohol abuse. By contrast, anxiety disorders do not appear to be specifically associated with CHC.

The acidic soluble fraction of whole saliva of type 1 diabetic children was analyzed by reversed phase (RP) 1 -HPLC-ESI-MS and compared with that of sex-and age-matched control subjects. Salivary acidic proline-rich phosphoproteins (aPRP), histatins, ␣-defensins, salivary cystatins, statherin, proline-rich peptide P-B (P-B), betathymosins, S100A8 and S100A9*(S100A9* corresponds to S100A9 vairant lacking the first four amino acids), as well some naturally occurring peptides derived from salivary acidic proline-rich phosphoproteins, histatins, statherin, and P-B peptide, were detected and quantified on the basis of the extracted ion current peak area. The level of phosphorylation of salivary acidic proline-rich phosphoproteins, histatin-1 (Hst-1), statherin and S100A9* and the percentage of truncated forms of salivary acidic proline-rich phosphoproteins was also determined in the two groups. The study revealed that statherin, proline-rich peptide P-B, P-C peptide, and histatins, were significantly less concentrated in saliva of diabetic subjects than in controls, while concentration of ␣-defensins 1, 2 and 4 and S100A9* was higher. The low concentration of P-C peptide was paralleled by high levels of some of its fragments. On the whole, the study highlighted the severe impairment of the repertoire of peptides involved in the safeguard of the oral cavity in children who have diabetes, as well as an higher concentration of the proinflammatory mediator S100A9* with respect to healthy children. Molecular & Cellular Proteomics 9:2099 -2108, 2010.Type 1 diabetes mellitus is a disease with universal distribution, affecting all populations (1) with an incidence increasing in Europe (2). Because type 1 diabetes involves many organs and tissues, signs and symptoms of diabetes can occur in the oral cavity. Indeed, several studies have shown that the prevalence, severity, and progression of periodontal diseases are significantly increased in diabetics, and the pathology is considered an important risk factor for periodontitis (3). The study of Lalla et al. (4) showed an association between diabetes and the increased risk for periodontal destruction even very early in life. Flow rate and composition of saliva are crucial for the maintenance of oral cavity health, and both have been found altered in diabetic subjects, although with contradictory findings. For instance, several studies reported a reduced resting salivary flow rate in adults and children who have type 1 diabetes with respect to healthy subjects (5-10), but it was also observed that stimulated saliva of diabetics and controls did not significantly differ (11,12). Total protein concentration of saliva was found either increased or not affected by the diabetic status. Lopez et al. (9) reported higher urea and total protein salivary content in diabetic children than in controls. Conversely, a study on 35 adult insulin-dependent diabetics demonstrated that they did not show a decreased saliva concentration of several innate antimicrobial factors (lysozyme, lactoferri...