Rodrigo Villamarim Soares

Expression of Membrane-associated Mucins MUC1 and MUC4 in Major Human Salivary Glands

Mucins are high molecular weight glycoproteins secreted by salivary glands and epithelial cells lining the digestive, respiratory, and reproductive tracts. These glyco-proteins, encoded in at least 13 distinct human genes, can be subdivided into gel-forming and membrane-associated forms. The gel-forming mucin MUC5B is secreted by mucous acinar cells in major and minor salivary glands, but little is known about the expression pattern of membrane-associated mucins. In this study, RT-PCR and Northern blotting demonstrated the presence of transcripts for MUC1 and MUC4 in both parotid and submandibular glands, and in situ hybridization localized these transcripts to epithelial cells lining striated and excretory ducts and in some serous acinar cells. The same cellular distribution was observed by immunohistochemistry. Soluble forms of both mucins were detected in parotid secretion after immunoprecipitation with mucin-specific antibodies. These studies have shown that membrane-associated mucins are produced in both parotid and submandibular glands and that they are expressed in different cell types than gel-forming mucins. Although the function of these mucins in the oral cavity remains to be elucidated, it is possible that they both contribute to the epithelial protective mucin layer and act as receptors initiating one or more intracellular signal transduction pathways.

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

The present investigation has characterised the influence of gustatory stimulation and duration of stimulation on the secretion pattern of salivary mucins MG1 and MG2 and non-mucin glycoproteins in submandibular/sublingual secretion (SMSL). Resting SMSL was collected for three 2 min intervals and stimulated SMSL was collected for ten 1 min intervals from six healthy subjects. Flow rates and total protein were significantly different under the two conditions. The secretion patterns of these proteins under resting and stimulated conditions was examined on periodic acid-Schiff reagent (PAS)-stained polyacrylamide gels using a Kodak Digital-Science Image Station. Image analyses revealed that the level of MG1 increased and the level of MG2 remained nearly the same after stimulation. Six other major glycoproteins (designated Band 1-6) were identified on the basis of their electrophoretic mobilities and immuno-reactivity on Western blots. After stimulation the intensity of Band 1 (lactoferrin and peroxidase) and Band 2 (amylase) decreased whereas the intensity of Band 3 (carbonic anhydrase), Band 4 (proline-rich glycoprotein) and Bands 5 and 6 (basic glycosylated proline-rich proteins) increased. These patterns probably reflect secretion from preformed vesicles since de novo synthesis would be unexpected within the time frame of these experiments. The variable patterns observed suggest that mucins and non-mucin glycoproteins in SMSL derive from different subsets of secretory vesicles, some of which may originate in mucous and others in serous acini, as well as in ductal cells. Quantification of mucins was performed by image analysis technology using purified MG1 and MG2 standards. Finally, the present investigation has shown that the secretory patterns of mucins and non-mucin glycoproteins from submandibular/sublingual glands are complex and represent an important aspect of salivary gland physiology.

MG2 and Lactoferrin Form a Heterotypic Complex in Salivary Secretions

Protein-protein interactions are necessary for homeostasis to be maintained and for biological systems to be integrated. Heterotypic complexes occur in saliva, and a complex between MG2 and SIgA has been suggested to promote microbial clearance from the oral cavity. In this study, we used a peptide display library to investigate previously unrecognized heterotypic complexes involving MG2 and other proteins. The library was panned with MG2 12 times, and analyses of clones identified the sequence Ala-Leu-Leu-Cys-, which occurs in salivary lactoferrin. Blotting experiments confirmed that MG2 and lactoferrin form a heterotypic complex in viro and in vivo. Periodate treatment of MG2 did not affect the interaction. A synthetic lactoferrin peptide containing the motif Ala-Leu-Leu-Cys-blocked the interaction between MG2 and lactoferrin, confirming the specificity of the interaction identified by panning. This complex may enhance the properties of these salivary components in the oral environment.

Impacto da doença periodontal na qualidade de vida de indivíduos diabéticos dentados

The aim of this study was to evaluate the potential impact of periodontal disease on quality of life in diabetics. A total of 159 dentate diabetic individuals registered at the Municipal Hospital in Itaúna, Minas Gerais, Brazil, were examined and interviewed. The clinical periodontal parameters recorded were: gingival bleeding, probing depth, and clinical attachment level. The OHIP-14 form was used to evaluate the impact of periodontal disease on quality of life. In relation to periodontal status, 15.7% of individuals were healthy, 35.2% presented gingivitis, and 49.1% periodontitis (27.7% in the mild-to-moderate and 21.4% in the advanced stages). Association between diagnosis of periodontal disease and impact on quality of life was significant in individuals with periodontitis (p < 0.001). Gingival bleeding, probing depth, and clinical attachment level > 4mm were associated with intensely negative impact on quality of life (p = 0.013, p < 0.001, and p = 0.012 respectively). Diabetics with mild-to-moderate and advanced periodontitis had more negative impact on quality of life than those who were periodontally healthy or with gingivitis.

The Effects of Duration and Intensity of Stimulation on Total Protein and Mucin Concentrations in Resting and Stimulated Whole Saliva

The present investigation has characterized the influence of the duration and intensity of stimulation on the secretion pattern of total protein and salivary mucins MG1 and MG2 in whole saliva. Resting and stimulated whole saliva was collected from six healthy subjects on 2 consecutive days. Whole saliva was collected for 2 five-minute intervals under resting conditions followed by collection under masticatory stimulation induced by the chewing of parafilm (1 g) at 10 or 60 strokes/min for 15 min. Flow rates were different under the 2 levels of stimulation. The concentration of total protein was different in resting and stimulated whole saliva but was not affected by the duration or intensity of stimulation. Analysis of mucin concentrations determined by capture ELISAs revealed that the pattern of MG1 secretion was similar to that of total protein. The pattern of MG2 secretion was unique in that no differences were observed in the concentration of this mucin under resting and stimulated conditions. This study shows that the pattern of protein secretion in whole saliva does not reflect the combined pattern observed for protein secretion in parotid and submandibular/sublingual glands, and that the secretion patterns of MG1 and MG2 in whole saliva are quite different from one another.

Structural characterisation of cysteines in a bacterial-binding motif of human salivary mucin MG2

Human salivary mucin MG2 is a 180 kDa glycoprotein secreted by submandibular/sublingual and minor salivary glands. Secreted MG2 contains a domain with the only two cysteines (Cys(45) and Cys(50)) present in the polypeptide backbone; in native and recombinant MG2 this domain is involved in mucin binding to oral microbes. As the reduction and alkylation of MG2 has been shown to abolish binding, the present study was undertaken to determine whether the cysteine residues exist in the dithiol or disulphide form. Electrophoretic analysis under reducing and non-reducing conditions showed that intermolecular disulphide bonds do not occur between MG2 molecules. The same incorporation of radiolabelled iodoacetamide into MG2 was obtained with or without prior reduction. When radiolabelled alkylated MG2 was digested with Endoproteinase Lys-C and the derived peptides were separated by reversed-phase high-performance liquid chromatography (RP-HPLC), radioactivity was found in two fractions. Mass spectral analyses of these fractions showed the presence of peptides Cys-Leu-His-Lys and Arg-Cys-Arg-Pro-Lys, both containing carboxymethylated cysteines. These results show that the cysteines in the structural motif associated with bacterial binding exist in the dithiol form, and suggest the potential use of cysteine-containing peptides as agents to modify interactions of MG2 with microbes and oral surfaces.

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.

Effect of vegetable oil (Brazil nut oil) and mineral oil (liquid petrolatum) on dental biofilm control

Dental biofilm control represents a basic procedure to prevent caries and the occurrence of periodontal diseases. Currently, toothbrushes and dentifrices are used almost universally, and the employment of good oral hygiene allows for appropriate biofilm removal by both mechanical and chemical control. The aim of this study was to evaluate the effectiveness of adding vegetable or mineral oil to a commercially available dentifrice in dental biofilm control. A comparison using the Oral Hygiene Index Simplified (OHI-S) was performed in 30 individuals who were randomly divided into three groups. Group 1 (G1) received a commercially available dentifrice; the composition of this dentifrice was modified by addition of mineral oil (Nujol®) for group 2 (G2) or a vegetable oil (Alpha Care®) for group 3 (G3) at 10% of the total volume, respectively. The two-way repeated-measures analysis of variance (two-way ANOVA) was used to test the effect of group (G1, G2 and G3) or time (baseline, 45 days and 90 days) on the OHI-S index scores. Statistical analysis revealed a significant reduction in the OHI-S at day 90 in G2 (p < 0.05) and G3 (p < 0.0001) in comparison to G1. Therefore, the addition of a vegetable or a mineral oil to a commercially available dentifrice improved dental biofilm control, suggesting that these oils may aid in the prevention and/or control of caries and periodontal disease.

Oral Congenital Melanocytic Nevus: A Rare Case Report and Review of the Literature

Melanocytic nevi are congenital or acquired benign proliferations of cells of melanocytic origin. Oral congenital melanocytic nevi are rare, and only a few cases have been reported in the literature. The purpose of this study is to present the clinical, histological and immunohistochemical features of an oral congenital melanocytic nevus in a 16-year-old female with an 11-year follow-up and to review the pertinent literature. The reported case is the fifth well-documented case report of oral congenital melanocytic nevus in the English literature and the first with a long period of follow-up, thereby making it an important contribution to the knowledge regarding this uncommon oral mucosa lesion.

A review and dental management of persons with craniosynostosis anomalies.

Individuals with craniofacial deformities have a higher risk of developing oral diseases. This article discusses craniosynostosis and its oral problems. Dental treatment protocols based on general, facial, oral, and psychological aspects are offered.