Tick hypersensitivity and human tick-borne diseases.

Immune-mediated hypersensitivity reactions to ticks and other arthropods are well documented. Hypersensitivity to ixodid (hard bodied) ticks is especially important because they transmit infection to humans throughout the world and are responsible for most vector-borne diseases in the United States. The causative pathogens of these diseases are transmitted in tick saliva that is secreted into the host while taking a blood meal. Tick salivary proteins inhibit blood coagulation, block the local itch response and impair host anti-tick immune responses, which allows completion of the blood meal. Anti-tick host immune responses are heightened upon repeated tick exposure and have the potential to abrogate tick salivary protein function, interfere with the blood meal and prevent pathogen transmission. Although there have been relatively few tick bite hypersensitivity studies in humans compared with those in domestic animals and laboratory animal models, areas of human investigation have included local hypersensitivity reactions at the site of tick attachment and generalized hypersensitivity reactions. Progress in the development of anti-tick vaccines for humans has been slow due to the complexities of such vaccines but has recently accelerated. This approach holds great promise for future prevention of tick-borne diseases.

The comparative inhibitory potency of salivary mucins against human immunodeficiency virus type 1.

MUC5B and MUC7 salivary mucins are reported to inhibit HIV-1 entry into target cells in vitro; however, their relative inhibitory potencies have not been quantitively compared. There is also conflicting evidence regarding whether HIV-1 infection diminishes mucins' inhibitory efficacy. We explored the effect of donor HIV-1 status upon the anti-HIV-1 potency of purified MUC5B and MUC7 while comparing their relative inhibitory potential using a pseudovirus-based neutralization assay. HIV status of sample donors had no detectable effect on HIV-1 inhibition by salivary mucins. MUC5B (median IC50 50 µg/ml, IQR 10-116 µg/ml) exhibited significantly more potent HIV-1 inhibition than MUC7 (median IC50 458 µg/ml, IQR 192->2000 µg/ml; Mann-Whitney U p < 0.0001). We suggest that larger size, gel-forming properties and extensive glycosylation of MUC5B allow more effective binding and aggregation of viral particles. MUC5B is also more abundant in the saliva and is therefore likely to make a substantially greater contribution to it's anti-HIV-1 properties.

Mucina y Enfermedad Periodontal / Mucin and periodontal disease

La enfermedad periodontal (EP) es una patología que afecta principalmente los tejidos que rodean a la pieza dentaria (PD) y se caracteriza, en la mayoría de los casos, por una exposición bacteriana que favorece una respuesta destructiva e inflamatoria del huésped, que conduce a la pérdida de inserción periodontal de la PD, provocando una marcada reabsorción ósea y la posible pérdida de las PD. El diagnóstico de EP implica evaluaciones clínicas y radiográficas, en la actualidad se están realizando diversas investigaciones para evaluar posibles compuestos en los fluidos orales a través de lo cual puede ser posible evaluar la presencia y gravedad de estas enfermedades, como así también el riesgo en los pacientes. Hay evidencias de la interacción de macromoléculas salivales, como las mucinas, con microorganismos específicos. De esta manera las mucinas, junto con otros productos de la saliva, ayudan a modular tanto el número como el tipo de proliferación de ciertos organismos y provocar la disminución de otros. La revisión de la literatura actual concluye que las mucinas salivales pueden servir como un parámetro bioquímico de la inflamación del periodonto (AU)

Periodontal disease (PD) is a pathology that mainly affects the tissues surrounding the tooth (PD) and is characterized, in most cases, by a bacterial exposure that favors a destructive and inflammatory response of the host, which leads to the loss of periodontal insertion of the PD, causing a marked bone resorption and the possible loss of the PD. The diagnosis of PD involves clinical and radiographic evaluations, at present several investigations are being carried out to evaluate possible compounds in oral fluids through which it may be possible to evaluate the presence and severity of these diseases, as well as the risk in patients. There is evidence of the interaction of salivary macromolecules, such as mucins, with specific microorganisms. In this way, mucins, together with other saliva products, help modulate both the number and type of proliferation of certain organisms and cause the decrease of others. The review of the current literature concludes that salivary mucins can serve as a biochemical parameter of inflammation of the periodontium (AU)

Human salivary proteins and their peptidomimetics: Values of function, early diagnosis, and therapeutic potential in combating dental caries.

Saliva contains a large number of proteins that play various crucial roles to maintain the oral health and tooth integrity. This oral fluid is proposed to be one of the most important host factors, serving as a special medium for monitoring aspects of microorganisms, diet and host susceptibility involved in the caries process. Extensive salivary proteomic and peptidomic studies have resulted in considerable advances in the field of biomarkers discovery for dental caries. These salivary biomarkers may be exploited for the prediction, diagnosis, prognosis and treatment of dental caries, many of which could also provide the potential templates for bioactive peptides used for the biomimetic management of dental caries, rather than repairing caries lesions with artificial materials. A comprehensive understanding of the biological function of salivary proteins as well as their derived biomimetic peptides with promising potential against dental caries has been long awaited. This review overviewed a collection of current literature and addressed the majority of different functions of salivary proteins and peptides with their potential as functional biomarkers for caries risk assessment and clinical prospects for the anti-caries application.

La saliva en pacientes edéntulos completos / Saliva in totally edentulous patients

La saliva es un fluido biológico importante en la fisiología de la cavidad bucal. El propósito de estarevisión fue considerar las relaciones entre el edentulismo completo y el perfil fisiológico de la saliva. El flujo salival, el pH y la capacidad tampón tienen relación con el número de dientes perdidos, presencia de prótesis dentales y métodos de determinación del flujo (saliva no estimulada o estimulada). Las fracciones de proteínas en muestras de saliva total muestran diferencias entre individuos dentados y pacientes edéntulos. Este conocimiento permitirá a los clínicos, comprender mejor el impacto del edentulismo sobre las propiedades de la saliva y planificar el tratamiento en consecuencia.

Saliva is an important biological fluid in oralphysiology. The purpose of this review wasto consider relationships among complete edentulism and saliva physiological profile. Salivaryflow rate, pH and buffer capacity has a relationwith the number of missing teeth, presence ofdental prostheses and methods of determining flow rate (unstimulated or stimulated saliva). Protein fractions in whole salivary samplesshow differences between dentate individuals and edentulous patients. This knowledge willenable clinicians to better understand the impactof edentulism on salivary properties and plan treatment accordingly.

Nitrophorins and nitrobindins: structure and function.

Classical all α-helical globins are present in all living organisms and are ordered in three lineages: (i) flavohemoglobins and single domain globins, (ii) protoglobins and globin coupled sensors and (iii) truncated hemoglobins, displaying the 3/3 or the 2/2 all α-helical fold. However, over the last two decades, all ß-barrel and mixed α-helical-ß-barrel heme-proteins displaying heme-based functional properties (e.g. ligand binding, transport and sensing) closely similar to those of all α-helical globins have been reported. Monomeric nitrophorins (NPs) and α1-microglobulin (α1-m), belonging to the lipocalin superfamily and nitrobindins (Nbs) represent prototypical heme-proteins displaying the all ß-barrel and mixed α-helical-ß-barrel folds. NPs are confined to the Reduviidae and Cimicidae families of Heteroptera, whereas α1-m and Nbs constitute heme-protein families spanning bacteria to Homo sapiens. The structural organization and the reactivity of the stable ferric solvent-exposed heme-Fe atom suggest that NPs and Nbs are devoted to NO transport, storage and sensing, whereas Hs-α1-m participates in heme metabolism. Here, the structural and functional properties of NPs and Nbs are reviewed in parallel with those of sperm whale myoglobin, which is generally taken as the prototype of monomeric globins.

Salivary acquired pellicle-inspired DpSpSEEKC peptide for the restoration of demineralized tooth enamel.

Salivary acquired pellicle (SAP) is a layer of proteins and glycoproteins of salivary origin that tightly coat the tooth surface. Statherin is an important part of the SAP. The initial six-peptide sequence DpSpSEEK (where pS denotes phosphorylated serine) of the N-terminus of statherin can be immobilized on a hydroxyapatite (HAP) surface and the negatively charged domains of the DpSpSEEK side chain can catch free Ca2+ in saliva due to the charge adsorption effect. In order to prepare more functional materials based on DpSpSEEK, we designed a cysteine-labeled peptide sequence DpSpSEEKC, which could conjugate other macromolecules by forming a sulfur-based linkage. In this work, we measured the adsorption of DpSpSEEKC to HAP by various methods. We also coated DpSpSEEKC on a demineralized tooth enamel surface to evaluate its biomineralization capacity. The DpSpSEEKC-coated samples were characterized after immersion in artificial saliva for 2 weeks. The results showed that DpSpSEEKC has a strong adsorption capacity to HAP and could induce remineralization on the demineralized tooth enamel surface due to its carboxyl and phosphate groups. Compared with the control samples, the mechanical properties of the DpSpSEEKC-coated samples were obviously improved. In conclusion, DpSpSEEKC can provide a potential method for restoring demineralized tooth enamel.

Salivary mucins promote the coexistence of competing oral bacterial species.

Mucus forms a major ecological niche for microbiota in various locations throughout the human body such as the gastrointestinal tract, respiratory tract and oral cavity. The primary structural components of mucus are mucin glycoproteins, which crosslink to form a complex polymer network that surrounds microbes. Although the mucin matrix could create constraints that impact inhabiting microbes, little is understood about how this key environmental factor affects interspecies interactions. In this study, we develop an experimental model using gel-forming human salivary mucins to understand the influence of mucin on the viability of two competing species of oral bacteria. We use this dual-species model to show that mucins promote the coexistence of the two competing bacteria and that mucins shift cells from the mixed-species biofilm into the planktonic form. Taken together, these findings indicate that the mucus environment could influence bacterial viability by promoting a less competitive mode of growth.

Cysteine-rich secretory protein 3 plays a role in prostate cancer cell invasion and affects expression of PSA and ANXA1.

Cysteine-rich secretory protein 3 (CRISP-3) is upregulated in prostate cancer as compared to the normal prostate tissue. Higher expression of CRISP-3 has been linked to poor prognosis and hence it has been thought to act as a prognostic marker for prostate cancer. It is proposed to have a role in innate immunity but its role in prostate cancer is still unknown. In order to understand its function, its expression was stably knocked down in LNCaP cells. CRISP-3 knockdown did not affect cell viability but resulted in reduced invasiveness. Global gene expression changes upon CRISP-3 knockdown were identified by microarray analysis. Microarray data were quantitatively validated by evaluating the expression of seven candidate genes in three independent stable clones. Functional annotation of the differentially expressed genes identified cell adhesion, cell motility, and ion transport to be affected among other biological processes. Prostate-specific antigen (PSA, also known as Kallikrein 3) was the top most downregulated gene whose expression was also validated at protein level. Interestingly, expression of Annexin A1 (ANXA1), a known anti-inflammatory protein, was upregulated upon CRISP-3 knockdown. Re-introduction of CRISP-3 into the knockdown clone reversed the effect on invasiveness and also led to increased PSA expression. These results suggest that overexpression of CRISP-3 in prostate tumor may maintain higher PSA expression and lower ANXA1 expression. Our data also indicate that poor prognosis associated with higher CRISP-3 expression could be due to its role in cell invasion.

The membrane-associated MUC1 improves adhesion of salivary MUC5B on buccal cells. Application to development of an in vitro cellular model of oral epithelium.

OBJECTIVES: The mucosal pellicle is a thin layer of salivary proteins, mostly MUC5B mucins, anchored to epithelial oral cells. This pellicle is involved in protection of oral mucosae against abrasion, pathogenic microorganisms or chemical xenobiotics. The present study aimed at studying the involvement of MUC1 in mucosal pellicle formation and more specifically in salivary MUC5B binding using a cell-based model of oral epithelium. DESIGN: MUC1 mRNAs were not detected in TR146 cells, and therefore a stable cell line named TR146/MUC1 expressing this protein was developed by transfection. TR146 and TR146/MUC1 were incubated with human saliva in order to evaluate retention of MUC5B by epithelial cells. RESULTS: The cell surface of both TR146 and TR146/MUC1 was typical of a squamous non-keratinized epithelium, with the presence of numerous microplicae. After incubation for 2h with saliva diluted in culture medium (1:1) and two washes with PBS, saliva deposits on cells appeared as a loose filamentous thin network. MUC5B fluorescent immunostaining evidenced a heterogeneous lining of confluent cell cultures by this salivary mucin but with higher fluorescence on TR146/MUC1 cells. Semi-quantification of MUC5B bound to cells confirmed a better retention by TR146/MUC1, evaluated by Dot Blot (+34.1%, p<0.05) or by immunocytochemistry (+44%, p<0.001). CONCLUSION: The membrane-bound mucin MUC1 is a factor enhancing the formation of the mucosal pellicle by increasing the binding of salivary MUC5B to oral epithelial cells. An in vitro model suitable to study specifically the function and properties of the mucosal pellicle is proposed.

Influence of saliva on the oral microbiota.

Saliva plays a major role in determining the composition and activity of the oral microbiota, via a variety of mechanisms. Molecules, mainly from saliva, form a conditioning film on oral surfaces, thus providing receptors for bacterial attachment. The attached cells use saliva components, such as glycoproteins, as their main source of nutrients for growth. Oral bacteria work sequentially and in a concerted manner to catabolize these structurally complex molecules. Saliva also buffers the pH in the biofilm to around neutrality, creating an environment which is conducive to the growth of many oral bacteria that provide important benefits to the host. Components of the adaptive and innate host defences are delivered by saliva, and these often function synergistically, and at sublethal concentrations, so a complex relationship develops between the host and the resident microbiota. Dysbiosis can occur rapidly if the flow of saliva is perturbed.

Opiorphin-dependent upregulation of CD73 (a key enzyme in the adenosine signaling pathway) in corporal smooth muscle cells exposed to hypoxic conditions and in corporal tissue in pre-priapic sickle cell mice.

The precise molecular mechanisms underlying priapism associated with sickle cell disease remain to be defined. However, there is increasing evidence that upregulated activity of the opiorphin and adenosine pathways in corporal tissue, resulting in heighted relaxation of smooth muscle, have an important role in development of priapism. A key enzyme in the adenosine pathway is CD73, an ecto-5'-nucleotidase (5'-ribonucleotide phosphohydrolase; EC 3.1.3.5) which catalyzes the conversion of adenosine mononucleotides to adenosine. In the present study we investigated how sickle cell disease and hypoxia regulate the interplay between opiorphin and CD73. In the corpora of sickle cell mice we observed significantly elevated expression of both the mouse opiorphin homolog mSmr3a (14-fold) and CD73 (2.2-fold) relative to non-sickle cell controls at a life stage before the exhibition of priapism. Sickle cell disease has a pronounced hypoxic component, therefore we determined if CD73 was also modulated in in vitro corporal smooth muscle (CSM) models of hypoxia. Hypoxia significantly increased CD73 protein and mRNA expression by 1.5-fold and 2-fold, respectively. We previously demonstrated that expression of another component of the adenosine signaling pathway, the adensosine 2B receptor, can be regulated by sialorphin (the rat opiorphin homolologue), and we demonstrate that sialorphin also regulates CD73 expression in a dose- and time-dependent fashion. Using siRNA to knockdown sialorphin mRNA expression in CSM cells in vitro, we demonstrate that the hypoxic upregulation of CD73 is dependent on the upregulation of sialorphin. Overall, our data provide further evidence to support a role for opiorphin in CSM in regulating the cellular response to hypoxia or sickle cell disease by activating smooth muscle relaxant pathways.

The functions of human saliva: A review sponsored by the World Workshop on Oral Medicine VI.

This narrative review of the functions of saliva was conducted in the PubMed, Embase and Web of Science databases. Additional references relevant to the topic were used, as our key words did not generate references which covered all known functions of saliva. These functions include maintaining a moist oral mucosa which is less susceptible to abrasion, and removal of micro-organisms, desquamated epithelial cells, leucocytes and food debris by swallowing. The mucins form a slimy coating on all surfaces in the mouth and act as a lubricant during such processes as mastication, formation of a food bolus, swallowing and speaking. Saliva provides the fluid in which solid tastants may dissolve and distributes tastants around the mouth to the locations of the taste buds. The hypotonic unstimulated saliva facilitates taste recognition. Salivary amylase is involved in digestion of starches. Saliva acts as a buffer to protect oral, pharyngeal and oesophageal mucosae from orally ingested acid or acid regurgitated from the stomach. Saliva protects the teeth against acid by contributing to the acquired enamel pellicle, which forms a renewable lubricant between opposing tooth surfaces, by being supersaturated with respect to tooth mineral, by containing bicarbonate as a buffer and urea and by facilitating clearance of acidic materials from the mouth. Saliva contains many antibacterial, antiviral and antifungal agents which modulate the oral microbial flora in different ways. Saliva also facilitates the healing of oral wounds. Clearly, saliva has many functions which are needed for proper protection and functioning of the human body.

Effect of Culicoides sonorensis salivary proteins on clinical disease outcome in experimental bluetongue virus serotype 8 infection of Dorset sheep.

The severity of bluetongue clinical disease in ruminants varies greatly depending on the outbreak serotype/strain, animal species/breed, and immune status of the herd. To predict disease risk from any of the 26 bluetongue virus (BTV) serotypes identified to date, experimental animal susceptibility studies are often conducted. Although sheep are the most susceptible livestock species in the US, infection of domestic breeds by injection of field isolates rarely produces the level of clinical disease observed in natural Culicoides midge­transmitted outbreaks. Thus, outbreak risk assessments based on experimental animal infections can underestimate the severity posed by a potential outbreak with a given virus serotype or strain. The aim of this study was to determine whether secreted Culicoides salivary proteins injected simultaneously with virus, to more closely mimic midge­delivered virus, would affect clinical disease outcome in a BTV­8 sheep susceptibility study. Eight sheep were intradermally inoculated with BTV­8; 4 received virus mixed with secreted Culicoides salivary proteins (BTV­8 + Cu SP), 4 received virus alone. Clinical signs were monitored daily for type, severity and duration. In sheep receiving the BTV­8 + Cu SP inoculum, clinical signs were more varied, more severe, and duration was three times longer compared to sheep receiving virus alone. These results suggest that Culicoides salivary proteins may play a contributing role in BTV pathology and that use of these proteins in experimental animal infections may allow development of a more robust target­host animal model.

The pellicle and erosion.

All tooth surfaces exposed to the oral environment are naturally coated by the acquired salivary pellicle. The pellicle is composed of adsorbed macromolecular components from saliva, gingival crevicular fluid, blood, bacteria, mucosa and diet. The pellicle (formed in situ/in vivo) functions as a semipermeable network of adsorbed salivary macromolecules and provides partial protection against acidic challenges; however, it cannot completely prevent demineralization of the tooth surface. The physiological pellicle reduces calcium and phosphate release from the enamel, and much less from the dentinal surface. With high probability, calcium- and phosphate-binding peptides and proteins adsorbed in the basal pellicle layer are of main relevance for the erosion-reducing effects of the natural salivary pellicle. Improvement of the pellicle's protective properties by dietary components (e.g. polyphenolic agents) might be a promising erosion-preventive approach that, however, needs validation by in situ experiments.

Antimicrobial defense systems in saliva.

The oral cavity is one of the most heavily colonized parts of our body. The warm, nutrient-rich and moist environment promotes the growth of a diverse microflora. One of the factors responsible for the ecological equilibrium in the mouth is saliva, which in several ways affects the colonization and growth of bacteria. In this paper, we discuss the various mechanisms by which the composition of the oral microflora is modulated by saliva. Saliva covers the oral hard and soft tissues with a conditioning film which governs the initial attachment of microorganisms, a crucial step in the setup of the oral microflora. It furthermore contains proteins which in the soluble phase bind to bacteria, blocking their adherence to surfaces. When the supply of nutrients is diminished, bacteria use salivary glycoproteins, especially high-molecular-weight mucins, as a source of complex carbohydrates, requiring a consortium of microorganisms for breakdown. In this way saliva promotes the complexity of the oral microflora, which in itself protects against overgrowth by few pathogenic species. Finally, saliva harbors a large panel of antimicrobial proteins which directly and indirectly inhibit uncontrolled outgrowth of bacteria. These include lactoferrin, lactoperoxidase, lysozyme and antimicrobial peptides. Under pathological conditions serum leakage occurs, and saliva mobilizes the humoral and cellular defense mechanisms in the blood. In sum, saliva favors the establishment of a highly diverse microflora, rather than a semisterile environment.

Saliva and wound healing.

Oral wounds heal faster and with less scar formation than skin wounds. One of the key factors involved is saliva, which promotes wound healing in several ways. Saliva creates a humid environment, thus improving the survival and functioning of inflammatory cells that are crucial for wound healing. In addition, saliva contains several proteins which play a role in the different stages of wound healing. Saliva contains substantial amounts of tissue factor, which dramatically accelerates blood clotting. Subsequently, epidermal growth factor in saliva promotes the proliferation of epithelial cells. Secretory leucocyte protease inhibitor inhibits the tissue-degrading activity of enzymes like elastase and trypsin. Absence of this protease inhibitor delays oral wound healing. Salivary histatins in vitro promote wound closure by enhancing cell spreading and cell migration, but do not stimulate cell proliferation. A synthetic cyclic variant of histatin exhibits a 1,000-fold higher activity than linear histatin, which makes this cyclic variant a promising agent for the development of a new wound healing medication. Conclusively, recognition of the many roles salivary proteins play in wound healing makes saliva a promising source for the development of new drugs involved in tissue regeneration.

Role of saliva in oral food perception.

Saliva is the first fluid that comes into contact with food during oral processing. Because saliva is the medium that bathes the taste receptors, is the fluid through which taste and aroma compounds are released into the oral cavity and is mixed continuously with food during bolus formation, it is an essential actor in oral chemosensory perception. The complexity of saliva composition, with compounds originating from different salivary glands, from gingival crevicular fluid, from micro-organisms and from food debris, together with its variable nature increases the possibilities for interactions with food compounds and for different roles in perception. These factors are increasingly being taken into account in current research on food perception. The aim of this paper is to review the principal roles of saliva in oral perception, with particular focus on chemosensory perception. These include the protection of taste buds, the effects of flow rates, salivary hormones, electrolytes and organic compounds, and finally the impact of perception on salivary secretions.

Lubrication.

Saliva is capable of decreasing friction force by at least 2 orders of magnitude when in between hydrophobic surfaces. This ability to lubricate is key to oral health, food processing and taste perception. In this paper different mechanisms of saliva lubrication are reviewed, and their interconnection is demonstrated using a simple physical framework. The current understanding of the roles of the molecular structure and physicochemical properties of major salivary proteins and protein complexes on lubrication is summarised and critically evaluated.