Patterns of secretion of mucins and non-mucin glycoproteins in human submandibular/sublingual secretion

A systematic review of salivary biomarkers in Parkinson's disease

The search for reliable and easily accessible biomarkers in Parkinson's disease is receiving a growing emphasis, to detect neurodegeneration from the prodromal phase and to enforce disease-modifying therapies. Despite the need for non-invasively accessible biomarkers, the majority of the studies have pointed to cerebrospinal fluid or peripheral biopsies biomarkers, which require invasive collection procedures. Saliva represents an easily accessible biofluid and an incredibly wide source of molecular biomarkers. In the present study, after presenting the morphological and biological bases for looking at saliva in the search of biomarkers for Parkinson's disease, we systematically reviewed the results achieved so far in the saliva of different cohorts of Parkinson's disease patients. A comprehensive literature search on PubMed and SCOPUS led to the discovery of 289 articles. After screening and exclusion, 34 relevant articles were derived for systematic review. Alpha-synuclein, the histopathological hallmark of Parkinson's disease, has been the most investigated Parkinson's disease biomarker in saliva, with oligomeric alpha-synuclein consistently found increased in Parkinson's disease patients in comparison to healthy controls, while conflicting results have been reported regarding the levels of total alpha-synuclein and phosphorylated alpha-synuclein, and few studies described an increased oligomeric alpha-synuclein/total alpha-synuclein ratio in Parkinson's disease. Beyond alpha-synuclein, other biomarkers targeting different molecular pathways have been explored in the saliva of Parkinson's disease patients: total tau, phosphorylated tau, amyloid-β1-42 (pathological protein aggregation biomarkers); DJ-1, heme-oxygenase-1, metabolites (altered energy homeostasis biomarkers); MAPLC-3beta (aberrant proteostasis biomarker); cortisol, tumor necrosis factor-alpha (inflammation biomarkers); DNA methylation, miRNA (DNA/RNA defects biomarkers); acetylcholinesterase activity (synaptic and neuronal network dysfunction biomarkers); Raman spectra, proteome, and caffeine. Despite a few studies investigating biomarkers targeting molecular pathways different from alpha-synuclein in Parkinson's disease, these results should be replicated and observed in studies on larger cohorts, considering the potential role of these biomarkers in determining the molecular variance among Parkinson's disease subtypes. Although the need for standardization in sample collection and processing, salivary-based biomarkers studies have reported encouraging results, calling for large-scale longitudinal studies and multicentric assessments, given the great molecular potentials and the non-invasive accessibility of saliva.

Lactoferrin and the development of salivary stones: a pilot study

Salivary stones (sialoliths) are calcified structures located in the ductal system of the major salivary glands. Their exact cause is not clear but in general they are characterized by concentric inorganic (hydroxyapatite) layers. The formation is a slow intermittent process which may result in enlargement of the sialolith causing obstruction of saliva secretion resulting in mealtime related pain and swelling of the affected salivary gland. Various studies reported the presence of organic material such as proteins and lipids in the core of sialoliths. In the present study the protein composition of twenty submandibular sialoliths was analyzed. It was found that proteins contributed on average 5% to the dry weight of submandibular stones whereby small salivary stones contained more extractable proteins than large salivary stones. Using a combination of SDS-PAGE gel electrophoresis and Western blotting, we identified α-amylase (in all stones; 100%), lysozyme (95%), lactoferrin (85%), secretory-IgA (75%), MUC7 (60%), complement C4 (60%) and C-reactive protein (35%). The presence, and the combinations, of lactoferrin, lysozyme, s-IgA and α-amylase in sialoliths was confirmed by ELISA. The gradually increasing size of a sialolith might provoke a local inflammatory response in the duct of the submandibular gland whereby the relatively low concentrations of lactoferrin and lysozyme may originate from neutrophils. The interaction of lactoferrin with s-IgA could contribute to the accumulation of lactoferrin in sialoliths. In summary, these results suggest a new pathophysiological role for lactoferrin, in the formation of sialoliths.

Lactoferrin and the development of salivary stones: a pilot study

Salivary stones (sialoliths) are calcified structures located in the ductal system of the major salivary glands. Their exact cause is not clear but in general they are characterized by concentric inorganic (hydroxyapatite) layers. The formation is a slow intermittent process which may result in enlargement of the sialolith causing obstruction of saliva secretion resulting in mealtime related pain and swelling of the affected salivary gland. Various studies reported the presence of organic material such as proteins and lipids in the core of sialoliths. In the present study the protein composition of twenty submandibular sialoliths was analyzed. It was found that proteins contributed on average 5% to the dry weight of submandibular stones whereby small salivary stones contained more extractable proteins than large salivary stones. Using a combination of SDS-PAGE gel electrophoresis and Western blotting, we identified α-amylase (in all stones; 100%), lysozyme (95%), lactoferrin (85%), secretory-IgA (75%), MUC7 (60%), complement C4 (60%) and C-reactive protein (35%). The presence, and the combinations, of lactoferrin, lysozyme, s-IgA and α-amylase in sialoliths was confirmed by ELISA. The gradually increasing size of a sialolith might provoke a local inflammatory response in the duct of the submandibular gland whereby the relatively low concentrations of lactoferrin and lysozyme may originate from neutrophils. The interaction of lactoferrin with s-IgA could contribute to the accumulation of lactoferrin in sialoliths. In summary, these results suggest a new pathophysiological role for lactoferrin, in the formation of sialoliths.

Streptococcus gordonii Poised for Glycan Feeding through a MUC5B-Discriminating, Lipoteichoic Acid-Mediated Outside-In Signaling Circuit

Many oral bacteria employ cell wall-anchored adhesins to bind to the salivary films coating the teeth and mucosal surfaces. Surface binding prevents clearance and facilitates catabolism of salivary film glycoproteins. We asked whether Streptococcus gordonii adhesin expression changes in response to surface salivary cues using a eukaryote-like, outside-in recognition and signaling circuit. To determine whether the cues were discriminated, S. gordonii was tested during cell adhesion and biofilm formation on a MUC5B-rich or lower-molecular-mass salivary fraction or an uncoated abiotic surface. Cells were recovered and analyzed for differences in gene expression and proteins in cell wall fractions. In salivary-free conditions, planktonic S. gordonii presented three prominent cell wall LPXTG-motif proteins, SGO_1487, SGO_0890, and MbpA (mucin-binding protein A; SGO_0707). During biofilm formation on MUC5B-coated surfaces, MbpA, a MUC5B-binding protein, and key genes in the tagatose and quorum-sensing pathways were strongly promoted. The response to MUC5B required the two-component system (TCS), streptococcal regulator of adhesins sensor and regulator (SraSR, SGO_1180/81), lipoteichoic acid (LTA), and the homologous paired adhesins, SspA and SspB (SspAB). LTA appears to link the outside signal (MUC5B) to intramembrane SraSR. Tagatose pathway gene expression may poise cells to metabolize MUC5B glycans and, with a quorum-sensing gene (luxS), may direct formation of a consortium to facilitate glycan cross-feeding by S. gordonii. We now show that a Gram-positive bacterium discriminates specific surface environmental cues using an outside-in signaling mechanism to apparently optimize colonization of saliva-coated surfaces. IMPORTANCE All organisms throughout the tree of life sense and respond to their surface environments. To discriminate among mucosal surface environmental cues, we report that Streptococcus gordonii recognizes a high-molecular-weight mucin glycoprotein, MUC5B, using the paired adhesins SspAB and lipoteichoic acid; the latter bridges the outside signal to an intramembrane two-component system to transcriptionally regulate a MUC5B-specific adhesin and genes that may facilitate glycan catabolism.

Pharyngeal Deposits Comprising Salivary Mucin in Tube-fed Elderly Patients: MUC2 and MUC7 Immunoreactivity

Several investigators have reported that oral membranous and pharyngeal viscous deposits developed in bedridden elderly persons requiring nursing care without oral intake. Therefore, this study aimed to clarify the origin of viscous deposits on the pharyngeal mucosa based on characteristics of salivary and tracheal secretory mucin. The participants were 35 elderly people who required nursing care. All 46 collected specimens, including 30 intraoral and 16 pharyngeal specimens, were stained against specific mucins secreted from the respiratory tract and saliva gland using antibodies anti-MUC2 and anti-MUC7, respectively. Out of 35 participants, the intraoral membranous deposits and deposits on the pharyngeal mucosa developed in 17 (48.6%) and 10 persons (28.6%), respectively. The pharyngeal deposits developed in 58.8% of participants who developed intraoral deposits. All pathological specimens shared microscopic findings of various combinations of eosinophilic lamellar structure and a pale-basophilic amorphous substance. Immunohistochemically, both the 30 oral and the 16 pharyngeal specimens obtained from 17 participants were consistently positive for MUC7 but negative for MUC2. In conclusion, we clarified that the mucoid component of both oral and pharyngeal deposits comprised MUC7 salivary mucin, which revealed that both deposits originated from the oral cavity. This result strongly suggests that oral care is intimately related to oral and pharyngeal conditions.

Salivary proteome of a Neotropical primate: potential roles in host defense and oral food perception

BACKGROUND

Saliva contains a very complex mixture of proteins for defense against microbiological pathogens and for oral food perception. Howler monkeys are Neotropical primates that can consume a mostly leaf diet. They are well known to thrive in highly disturbed habitats where they may cope with a diversity of dietary challenges and infection risks. We aimed to describe the salivary proteome of howlers to contribute to better understanding of their physiology.

METHODS

We analyzed the salivary proteins of wild black howler monkeys (Alouatta pigra), by SDS-PAGE-1-D and Nano LC-MS/MS and categorized them by their function involved in host defense and oral food perception.

RESULTS

Our proteomic analysis identified 156 proteins in howler saliva including a number of host defense peptides that are the first line of defense in mammals, such as defensin, cathelicidin, dermcidin, and lactotransferrin, and proteins with anti-bacterial, anti-fungal, and anti-viral capacity, such as IgA, IgG, IgM, BPI, salivary heat shock 70 kDa protein, beta-2-microbulin, and protein S-100. We also identified key proteins necessary for taste perception, including salivary carbonic anhydrase VI, cystatin D, IgA, and fatty acid-binding protein. Proteins to detect astringent foods were identifying, including four members of cystatins (A, B, C and D), lactoperoxidase, and histidine-rich proteins. No chitinase and amylase were identified as would be expected because howlers do not eat insects and little starch. These findings provide basic information to future studies in oral biology, ingestive physiology, and physiological ecology of mammals and non-human primates.

Histopathological evaluation of oral membranous substance in bedridden elderly persons without oral intake in Japan

OBJECTIVES

The aim of this study was to clarify by histopathological examination the origin of oral membranous substances deposited on the palate, tongue, buccal mucosa and teeth.

BACKGROUND

Several investigators have reported membranous substances deposited in the mouths of bedridden elderly persons requiring nursing care without oral intake. However, the precise nature and origin of the substances are poorly understood.

METHODS

Sixty-nine specimens were taken from the oral cavity of bedridden patients, that is, the palate, dorsum of the tongue, the cheek and teeth. Sections were stained with haematoxylin and eosin stain, alcian-blue and periodic acid-Schiff stain (AB-PAS) and antibodies for pankeratin (AE1AE3) and leukocyte common antigen (LCA).

RESULTS

All specimens showed a film-like nature coloured from tan to white, accompanied by a mucous substance. Histologically, specimens of all sites had a similar feature of the combination of basophilic amorphous and eosinophilic lamellar features. The basophilic substance was positive for AB-PAS, and PAS-positive glycogen granules were also noted in the lamellar structure. Immunochemistry revealed various degrees of pankeratin positive substance and LCA-positive inflammatory cell infiltration.

CONCLUSION

The oral membranous substance was composed of keratin and mucin with inflammation. These results suggest that the deposition of the oral membranous substance is a pathological condition or oral mucositis caused by dry mouth.

Does diet influence salivary enzyme activities in elephant species?

Asian elephants (Elephas maximus) and African elephants (Loxodonta africana) are herbivore generalists; however, Asian elephants might ingest a higher proportion of grasses than Africans. Although some studies have investigated nutrition-specific morphological adaptations of the two species, broader studies on salivary enzymes in both elephant species are lacking. This study focuses on the comparison of salivary enzymes activity profiles in the two elephant species; these enzymes are relevant for protective and digestive functions in humans. We aimed to determine whether salivary amylase (sAA), lysozyme (sLYS), and peroxidase (sPOD) activities have changed in a species-specific pattern during evolutionary separation of the elephant genera. Saliva samples of 14 Asian and eight African elephants were collected in three German zoos. Results show that sAA and sLYS are salivary components of both elephant species in an active conformation. In contrast, little to no sPOD activity was determined in any elephant sample. Furthermore, sAA activity was significantly higher in Asian compared with African elephants. sLYS and sPOD showed no species-specific differences. The time of food provision until sample collection affected only sAA activity. In summary, the results suggest several possible factors modulating the activity of the mammal-typical enzymes, such as sAA, sLYS, and sPOD, e.g., nutrition and sampling procedure, which have to be considered when analyzing differences in saliva composition of animal species.

In vivo interactions between procyanidins and human saliva proteins: effect of repeated exposures to procyanidins solution

The general accepted mechanism for astringency arises from the interaction between tannins and salivary proteins (SP) resulting in (in)soluble aggregates. By HPLC analysis, it was observed that repeated sips of procyanidins (PC) solution practically depleted aPRPs (∼14%) and statherin (∼2%), and significantly reduced the amount of gPRPs. On the other hand, bPRPs were not significantly affected. In the analysis performed after the last exposure to PC solution, it was seen a significant recovering of the chromatographic peaks corresponding especially to aPRPs (∼74%) and statherin (∼80%). In vitro interaction between SP and PC results in the decrease of the chromatographic peaks of aPRPs and statherin, suggesting that these proteins were involved in the formation of a significant quantity of insoluble complexes. In general, the results suggest that the different families of SP can be involved in different stages of the development of astringency sensation.

Chronic alcohol consumption promotes alterations on salivary gland regeneration process

The aim of this study is to investigate the histological effect of alcohol ingestion on the regeneration of the submandibular gland (SMG) in rats. Twelve 60-day-old male Wistar rats were randomized into two experimental groups. Test group (TG) animals ingested 40° GL of alcohol for 45 days before surgery, being its concentration gradually increased 10° GL/week for 4 weeks to achieve the final concentration of 40° GL. The control group (CG) received water during the whole experimental period. One-third of the left SMG lobe was removed. Three and seven days after, the whole gland was excised and analyzed. In the TG, the inflammatory process was pronounced when comparing the CG on day 3. The inverse aspect was observed on day 7, associated with an advanced parenchyma development. Changes in laminin expression and glycoproteins production were observed in the TG, causing advanced morphogenesis and delay in cytodifferentiation during the salivary gland regeneration, probably due to alcohol effects. Animals who received ethanol showed alterations in the pattern of glandular regeneration.

Differential expression of salivary glycoproteins in aggressive and chronic periodontitis

OBJECTIVES

The aim of this study was to compare the pattern of secretion and the expression of mucin glycoprotein-2 (MG2) and lactoferrin in individuals with or without periodontitis.

MATERIAL AND METHODS

Five individuals with aggressive periodontitis (APG), 5 with generalized chronic periodontitis (CPG) and 5 without periodontitis (CG) were enrolled after informed consent. Non-stimulated and stimulated submandibular and sublingual saliva was collected and samples analyzed by Western blot probed with specific antibodies.

RESULTS

Stimulated and non-stimulated salivary flow rates did not differ among groups. Western blot analysis revealed that stimulation led to: an increase in MG2 expression in all groups, and to lactoferrin expression in APG and CPG. In non-stimulated saliva, CG exhibited the highest expression of both glycoproteins. In stimulated saliva, CG exhibited the highest expression of MG2, whereas APG the highest of lactoferrin.

CONCLUSIONS

The pattern of secretion of MG2 and lactoferrin in health and disease is complex. Although the present study analyzed samples from a limited number of participants, the reduced expression of MG2 and lactoferrin in APG and CPG under non-stimulated condition, the predominant circumstance of salivary secretion during the day, suggests that these salivary constituents may play a role in the etiopathogenesis of these diseases.

The role of salivary proteins in the mechanism of astringency

Understanding astringency has focused on the interaction of tannins with the salivary proline-rich proteins (PRPs), although it remains unclear if other astringents precipitate the PRPs or how this interaction relates to sensory perceptions of astringency. We used 2 approaches to compare how distinct classes of astringent compounds interacted with the salivary PRPs and mucins. Using sodium dodecyl sulfate polyacrylamide gel electrophoresis, we evaluated protein patterns and characterized the salivary proteins present in the supernatants and pellets of pooled saliva assayed with tannin, alum, and hydrochloric acid solutions. Tannins and alum precipitated many of the PRPs, but acid did not. Mucins were precipitated by both the acid and alum, but not by the tannins. From our research, it appears that the precipitation of salivary proteins may be involved in the mechanism of astringency, but the precipitation of PRPs is not requisite for the development of astringency. We also measured mucin and deoxyribonucleic acid content of expectorated solutions of astringents that panelists swished in their mouths to determine if astringency was associated with a loss of oral lubricating films.

Sialic acid reduction in the saliva of streptozotocin induced diabetic rats

OBJECTIVE

Diabetes causes changes in the salivary glands and in the composition of saliva, as well as symptoms such as dry mouth and hyposalivation. Therefore, this study aimed at investigating changes in salivary secretion and composition, in response to parasympathetic stimuli, in diabetic rats induced with streptozotocin.

DESIGN

Diabetes was induced by a single intraperitoneal injection of streptozotocin. Thirty days after diabetes induction, the animals were anaesthetized and salivation was stimulated by an intraperitoneal injection of Pilocarpine (0.6mg/kg body weight) dissolved in distilled water. Saliva was collected for 40min and immediately stored at -80°C until analysis. The salivary flow rate, amount of total protein, amylase and peroxidase activities, and free and total sialic acid contents were measured.

RESULTS

Salivary flow rate was reduced in the diabetic group (p<0.05). Moreover, increases in total protein amount and in amylase and peroxidase activities were observed in diabetic animals. No difference was observed for free sialic acid content between groups. On the other hand, a significantly decrease in the total sialic acid content was observed in the diabetic group (p<0.05).

CONCLUSIONS

Our findings suggest that a decrease in sialic acid in the saliva of diabetic animals can be related to xerostomia reported by diabetic patients. However, further clinical trials are needed to verify if the decrease in sialic acid also occurs in human saliva.

The effect of tannins on Mediterranean ruminant ingestive behavior: the role of the oral cavity

Sheep, cattle and goat are domestic ruminants of significant economic interest in the Mediterranean region. Although sharing the same pasture ranges, they ingest different plants and plant parts and, consequently different levels of tannins. This suggests an ability to detect and adapt ingestion according to animal physiological limits of tolerance for plant secondary metabolites. This review will detail the effects of dietary tannins on feeding behavior, and the role of the oral cavity in this process, with focus on such ruminant species. The role of salivary protein profile in tannin perception in the oral cavity, and as a defense mechanism, will be discussed.

Long-term follow-up after submandibular gland transplantation in severe dry eyes secondary to cicatrizing conjunctivitis

PURPOSE

To evaluate the long-term results of autologous submandibular gland transplantation in eyes with cicatrizing conjunctivitis and to determine biomechanical and biochemical features of the resulting salivary tear film.

DESIGN

Prospective, observational case series.

METHODS

Fifteen eyes with cicatrizing conjunctivitis with a viable autologous submandibular gland transplantation were compared with 10 eyes with cicatrizing conjunctivitis and a failed submandibular gland transplantation or no submandibular gland transplantation. Best-corrected visual acuity, frequency of tear substitute instillation, severity of dry eye discomfort, lid margin erythema, conjunctival hyperemia, corneal epithelial edema, tear film break-up time, Schirmer test results, and corneal fluorescein and conjunctival Rose Bengal staining were evaluated. In a subgroup central corneal thickness and sensitivity, corneal epithelial barrier function, conjunctival and lid margin flora, and conjunctival impression cytologic analysis results were evaluated. In 3 patients, preoperative and postoperative tear samples were analyzed for viscosity, surface tension, and presence of mucins.

RESULTS

Submandibular gland autotransplantation resulted in long-term improvement of subjective, objective, and some ocular surface parameters. Salivary mucins were detectable in salivary tears after submandibular gland transplantation. The viscosity of salivary tears was more similar to normal saliva and the surface tension was intermediate between the 2 original secretions.

CONCLUSIONS

Submandibular gland autotransplantation provides long-term relief from pain and reduces the need for frequent installation of lubricants.

Interaction of copper and human salivary proteins

Interaction of taste molecules with saliva is the first step in the flavor perception process. Saliva is assumed to influence copper-induced sensation by controlling the copper solubility or causing astringency via binding of proteins with copper. This study was performed to identify the nature of copper-protein interactions in relation to the sensory perception of copper. Saliva was treated with CuSO4 x 5H2O at levels of 0, 2.5, 5, 10, 20, or 40 mg/L, and changes in salivary proteins were analyzed using high performance liquid chromatography (HPLC) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Protein peaks that showed changes in HPLC were characterized with SDS-PAGE. HPLC analysis revealed that copper treatment up to 40 mg/L decreased several proteins, including the dominant peak, by 70%. This peak was composed of alpha-amylase, a secretory component, and basic proline-rich proteins. SDS-PAGE results showed that salivary proteins of molecular weight 29 kDa and 33 kDa precipitated when copper was added at concentrations > or =10 mg/L. This study provides biochemical information for understanding perception mechanisms of copper sensation.

Saliva characteristics and individual sensitivity to phenolic astringent stimuli

Astringency sensation is due to interactions between salivary proteins and phenols and is based on an increased-friction mechanism. Modifications to the profile of salivary proteins and their concentration could affect tannin/protein reactions and hence the intensity of perceived astringency. Salivary characteristics of 65 subjects were compared after abstention from phenol-containing food and immediately after ingestion of tannic acid. The effect of stimulation on saliva characteristics was expressed in terms of D value, computed as the arithmetic difference between values found in saliva samples from the 2 conditions. Based on D values, subjects were clustered in two groups. Cluster 1 (Cl1, 53 cases) was characterized by low D values thus indicating that the basal saliva condition was quickly restored in these subjects. Cluster 2 (Cl2) was composed of 12 subjects whose basal salivary condition was not quickly restored, particularly in terms of salivary protein concentration and profile and saliva haze-forming capacity. Sensory data showed that subjects capable of maintaining constant saliva characteristics were less sensitive to astringent stimuli than subjects in which the same stimulations induced significant saliva modifications. The results suggest that a large proportion of the population are able to maintain their salivary protein concentration and simultaneously intercept and inactivate dietary tannins.

Carbachol-induced in vitro secretion of certain human submandibular proteins investigated by mass-spectrometry

OBJECTIVE

To investigate protein content of saliva produced in vitro by samples of human submandibular gland following stimulation with the muscarinic agent carbachol.

DESIGN

Tissue samples, obtained at surgery from seven patients and showing normal morphological appearance, were tested for 30 min: in absence of carbachol and atropine; in presence of carbachol (10 microM); in presence of carbachol (10 microM) and atropine (20 microM); or in presence of just atropine (20 microM). Medium was analysed by high-performance liquid chromatography-mass-spectrometry. Neither before nor during surgery were the patients exposed to drug treatments that were likely to influence the in vitro secretion.

RESULTS

Proline-rich proteins (PRP)-1 and -3, peptide PC and PB, statherin, cystatins SN, S1 and S2 were invariably found in control gland tissue medium. Mean concentrations of these proteins/peptides in the medium were non-proportionally elevated following carbachol exposure to the gland tissues. Difference between basal release and carbachol-induced secretion achieved statistical significance as to all the proteins/peptides under study but for statherin. Atropine alone or atropine plus carbachol caused no significant changes compared to the basal release of proteins/peptides.

CONCLUSIONS

In vitro studies on salivary glands make it possible to study protein secretion from individual glands and thus, to reveal the contribution of the various types of gland to protein/peptide content of whole saliva. The disproportional responses to carbachol may imply that the proteins/peptides are not confined to the same cells or to the same intracellular locations and are therefore not secreted as packages at parasympathetic cholinergic activity.

Characterization of esophageal submucosal glands in pig tissue and cultures

The submucosal glands (SMGs) of the pig esophagus, like the human, secrete mucin and bicarbonate, which help in luminal acid clearance and epithelial protection. The aim of this study was to characterize histochemically the esophageal SMGs and a primary culture obtained from these glands. Tissues and cultures were stained with hematoxylin and eosin, periodic acid Schiff, Alcian blue, lectins, or cytokeratins. In the perfused esophagus, addition of carbachol increased mucin secretion by approximately 2-fold. The results indicate that [1] a method for culturing SMG cells was developed; [2] conventional staining indicates the presence of sulfated, acidic, and neutral mucopolysaccharides in glands and cultures; [3] lectin binding indicates the presence of N-acetyl glucosamine, N-acetyl neuraminic acid, N-acetyl galactosamine, and alpha-L: -fucose in mucous cells and cultures; [4] cytokeratin and lectin staining indicated similarities with Barrett epithelium (columnar metaplasia of the esophagus); and [5] cholinergic agonists enhance mucin secretion and this could play a significant role in esophageal protection.

Molecular alterations of parotid saliva in infantile chronic recurrent parotitis

Infantile chronic recurrent parotitis (ICRP) is an insidious disease whose etiopathogenesis remains an enigma. Alterations in the physical appearance of parotid saliva from ICRP patients have been frequently reported. However, sialochemical studies in regard to ICRP are very rare. The aim of this study was to determine whether saliva of ICRP patients presents major physicochemical and biochemical alterations compared with saliva from paired healthy controls. Parotid, whole, and submandibular/sublingual saliva was collected at an asymptomatic stage from 33 ICRP patients (5-16 y old, both sexes) and from 33 sex- and age-matched healthy controls. Saliva was analyzed for protein concentration, mode of protein diffusion on cellulose membranes, unidimensional sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis protein profiles and zymographic profiles of metalloproteinase 2 (MMP-2) and metalloproteinase 9 (MMP-9). Parotid saliva of ICRP patients showed an increased protein concentration, altered mode of protein diffusion, a higher frequency of polypeptide bands of 43, 37, 33, 29, 26, 16, and 10 kD, higher asymmetry in the polypeptide profiles of both contralateral parotid saliva, and an increase in the frequency of MMP-2 and MMP-9. Parotid saliva of patients with ICRP is molecularly altered with respect to normal saliva. Some of the molecular differences could be related to the etiopathogenesis of the disease.

Analysis of the human saliva proteome

Interest in the characterization of the salivary proteome has increased in the last few years. This review discusses the different techniques and methodologies applied to the separation and identification of salivary proteins. Nowadays, proteomic techniques are the state of the art for the analysis of biologic materials and saliva is no exception. 2D electrophoresis and tryptic digest analysis by mass spectrometry are the typical methodology, but new approaches using 2D liquid chromatography/mass spectrometry methods have already been introduced for saliva analysis. Due to their important physiologic role in the oral cavity, low-molecular-weight proteins and peptides are also included in this article and the methodologies discussed.

Proteomic analysis of human whole and parotid salivas following stimulation by different tastes

Whole and parotid salivas, collected after stimulation with tastants, were analyzed by 2D electrophoresis and mass spectrometry. In whole saliva, the number of proteins affected by taste stimulation increased in the order sweet < umami < bitter < acid. Annexin A1 and calgranulin A, involved in inflammation, were over-represented after umami, bitter, and sour stimulations. Their low abundance or absence in parotid saliva after bitter stimulation suggested that they originated from other oral glands or tissues.

Patterns and variability in electrophoretic polypeptide profiles of human saliva in a healthy population

Electrophoretic polypeptide profiles of normal human saliva differ markedly between different reports. Since both methodological variations and polymorphism may explain these differences, in this study we aimed to establish whether or not the salivary electrophoretic polypeptide profiles of subjects from a healthy population share discrete molecular features. To this end, parotid, submandibular/sublingual and whole salivas were collected separately from each of 40 young and 34 elderly clinically healthy adults and processed for SDS-polyacrylamide gel electrophoresis and Coomassie blue staining. Each type of glandular saliva displayed a different group of invariant (i.e. present in every subject) electrophoretic polypeptide bands while whole saliva showed a profile that reflected mostly the combined contribution of the major salivary glands. Some minor variant (i.e. absent in some subjects) bands were identified in each type of saliva. Regarding those interindividual variations, no age- or sex-dependence was appreciated. Altogether, these results demonstrate the occurrence of distinctive electrophoretic polypeptide patterns, in addition to some minor variations, for each type of normal saliva, thus providing a background for further populational studies on salivary polypeptide profiles.

Binding of the streptococcal surface glycoproteins GspB and Hsa to human salivary proteins

GspB and Hsa are homologous surface glycoproteins of Streptococcus gordonii that bind sialic acid moieties on platelet membrane glycoprotein Ibalpha. Since this species is an important member of the oral flora, we examined the direct binding of these adhesins to human salivary proteins. Both GspB and Hsa bound low-molecular-weight salivary mucin MG2 and salivary agglutinin. Hsa also bound several other salivary proteins, including secretory immunoglobulin A. Screening of six oral streptococcal isolates revealed that at least two of the strains expressed GspB homologues. These results indicate that GspB-like adhesins may be important for oral bacterial colonization.