Defensins in the oral cavity: distribution and biological role

Impact of diet and bacterial supplementation regimes on Orius strigicollis microbiota and life history performance

Given the growing interest in manipulating microbiota to enhance the fitness of mass-reared insects for biological control, this study investigated the impact of an artificial diet on the microbiota composition and performance of Orius strigicollis. We compared the microbiota of O. strigicollis fed on an artificial diet and moth eggs via culturing and 16S rRNA gene amplicon sequencing. Subsequently, we assessed life history traits and immune gene expression of O. strigicollis fed on the artificial diet supplemented with Pantoea dispersa OS1. Results showed that microbial diversity remained largely unaffected by the artificial diet, with similar microbiota compositions in both diet groups. OS1, a minor member of the microbiota but significantly enriched in bugs fed on the artificial diet, improved nymphal survival rates and shifted adult longevity-reproduction life history in females. Additionally, OS1 supplementation elevated the transcription of antimicrobial peptide diptericin. According to population parameters, the group receiving OS1 only during the nymphal stage showed higher population growth potential compared to the group supplemented across all life stages. These findings reveal the resilience of O. strigicollis microbiota under distinct dietary conditions and highlight the potential of using natural symbionts and specific supplementation regimes to improve Orius rearing for future biocontrol programs.

Comparison between hangeshashinto and dexamethasone for IL-1α and β-defensin 1 production by human oral keratinocytes

OBJECTIVE

Human β-defensin 1 (hBD-1) is a antimicrobial peptide that is constantly secreted by oral tissues. Hangeshashinto (HST), a traditional Japanese medicine, has been reported to be effective against stomatitis. This study aimed to clarify the profile of HST by comparing the system of production of interleukin-1α (IL-1α) and hBD-1 in human oral mucosal epithelial cells with dexamethasone (DEX), a steroid used for the treatment of stomatitis.

METHODS

Human oral keratinocytes (HOK) were treated with HST, DEX, or HST components (baicalein, baicalin, berberine, and glycyrrhizin) for 24 h, and subsequently cultured for 24 h with or without Pam3CSK4 or lipopolysaccharide (LPS). The cell supernatants, total RNA, and intracellular proteins were collected, and changes in IL-1α and hBD-1 protein production and gene expression were evaluated using ELISA and RT-PCR. The phosphorylation of NF-kB and the cell proliferative ability of HOK were evaluated by western blotting and XTT assay, respectively.

RESULTS

DEX (0.01-10 μM) significantly suppressed IL-1α and hBD-1 production induced by either Pam3CSK4 or LPS, and also decreased cell growth. In contrast, HST inhibited Pam3CSK4- and LPS-induced IL-1α production at a concentration range of 12.5-100 μg/mL without affecting the cell proliferative capacity and hBD-1 production of HOK. Baicalein and baicalin, which are flavonoid ingredients of HST, showed anti-IL-1α production.

CONCLUSION

HST may be useful as a therapeutic agent for stomatitis and other inflammatory diseases of the oral cavity.

Role of innate host defense proteins in oral cancerogenesis

It is nowadays well accepted that chronic inflammation plays a pivotal role in tumor initiation and progression. Under this aspect, the oral cavity is predestined to examine this connection because periodontitis is a highly prevalent chronic inflammatory disease and oral squamous cell carcinomas are the most common oral malignant lesions. In this review, we describe how particular molecules of the human innate host defense system may participate as molecular links between these two important chronic noncommunicable diseases (NCDs). Specific focus is directed toward antimicrobial polypeptides, such as the cathelicidin LL-37 and human defensins, as well as S100 proteins and alarmins. We report in which way these peptides and proteins are able to initiate and support oral tumorigenesis, showing direct mechanisms by binding to growth-stimulating cell surface receptors and/or indirect effects, for example, inducing tumor-promoting genes. Finally, bacterial challenges with impact on oral cancerogenesis are briefly addressed.

The Antimicrobial Peptide LL-37 as a Predictor Biomarker for Periodontitis with the Presence and Absence of Smoking: A Case-Control Study

Background

A major issue is finding a valid biomarker able to diagnose periodontal disease with the presence and absence of risk factors. Indeed, the association between smoking and periodontal diseases and its impact on the manifestation of antimicrobial peptides has been delineated in clinical and epidemiological investigations. The antimicrobial peptide cathelicidin (LL-37) is pivotal in preserving periodontal health.

Objectives

This investigation examines and contrasts the levels of cathelicidin in the saliva of smokers and nonsmokers of periodontitis. The study also seeks to establish this biomarker's diagnostic ability to differentiate between periodontal health and disease.

Materials and Methods

The study involved the collection of unstimulated saliva samples from 160 participants, comprising 80 patients diagnosed with periodontitis (40 of whom were smokers and 40 were nonsmokers) and 80 periodontitis-free individuals (40 smokers and 40 nonsmokers). The clinical periodontal parameters were assessed, including recording the probing pocket depth, the level of clinical attachment, and the percentage of bleeding on probing. Subsequently, enzyme-linked immunosorbent assays were conducted to quantify the protein levels of LL-37 in the saliva samples obtained from the subjects mentioned above.

Results

The highest level of salivary LL-37 was found in the nonsmoker periodontitis (NSP) patients, followed by the group of smoker periodontitis (SP) and then nonsmoker healthy (NSH) group, while the lowest level was found in the healthy smoker (HS) group. At the same time, the LL-37 seems to be a very good biomarker in differentiating periodontal health from disease with the presence and absence of smoking.

Conclusion

Periodontitis results in a significant elevation of salivary LL-37 levels in smoker and nonsmoker patients compared to healthy individuals. These levels are positively correlated with the periodontal parameter and can serve as a valuable diagnostic tool to predict periodontitis, whereas smoking significantly reduces these levels.

Probiotic Bifidobacteria in Managing Periodontal Disease: A Systematic Review

Although various probiotic organisms have been evaluated for their utility in the management of periodontitis, their strain-specific mechanisms of action are still unclear. We aimed to systematically review the effect of bifidobacterial probiotics on periodontopathogens and host immune responses in periodontal diseases. An electronic search of articles published until June 2022 in Medline, PubMed, Web of Science, and Cochrane Library databases was performed. Randomised controlled trials (RCTs) and in vitro and animal studies were assessed, and the data regarding antimicrobial properties, immunomodulation, and clinical outcomes were analysed. A total of 304 studies were screened, but only 3 RCTs and 6 animal and in vitro studies met the inclusion criteria. The use of different strains of bifidobacteria led to (1) a reduction of key players of the red complex periodontopathogens; (2) reduced levels of pro-inflammatory cytokines (eg, interleukin [IL]1-β and IL-8) and higher levels of anti-inflammatory cytokines (IL-10); (3) enhanced levels of osteoprotegerin and reduced levels of receptor activator of nuclear factor kappa-B ligand; and (4) a reduction of the dental plaque, bleeding on probing, alveolar bone loss, and clinical attachment loss. Bifidobacterial probiotic adjuvant supplementation, especially with Bifidobacterium animalis subspecies lactis, appears to help improve clinical periodontal parameters and develop a healthy plaque microbiome through microbiological and immunomodulatory pathways. Further human and animal studies are warranted prior to the therapeutic use of bifidobacteria in the routine management of periodontal infections.

Important Roles and Potential Uses of Natural and Synthetic Antimicrobial Peptides (AMPs) in Oral Diseases: Cavity, Periodontal Disease, and Thrush

Numerous epithelial cells and sometimes leukocytes release AMPs as their first line of defense. AMPs encompass cationic histatins, defensins, and cathelicidin to encounter oral pathogens with minimal resistance. However, their concentrations are significantly below the effective levels and AMPs are unstable under physiological conditions due to proteolysis, acid hydrolysis, and salt effects. In parallel to a search for more effective AMPs from natural sources, considerable efforts have focused on synthetic stable and low-cytotoxicy AMPs with significant activities against microorganisms. Using natural AMP templates, various attempts have been used to synthesize sAMPs with different charges, hydrophobicity, chain length, amino acid sequence, and amphipathicity. Thus far, sAMPs have been designed to target Streptococcus mutans and other common oral pathogens. Apart from sAMPs with antifungal activities against Candida albicans, future endeavors should focus on sAMPs with capabilities to promote remineralization and antibacterial adhesion. Delivery systems using nanomaterials and biomolecules are promising to stabilize, reduce cytotoxicity, and improve the antimicrobial activities of AMPs against oral pathogens. Nanostructured AMPs will soon become a viable alternative to antibiotics due to their antimicrobial mechanisms, broad-spectrum antimicrobial activity, low drug residue, and ease of synthesis and modification.

Expression of anti-fungal peptide, β-defensin 118 in oral fibroblasts induced by C. albicans β-glucan-containing particles

Objective:

Methodology:

Results:

Conclusion:

Harvesting of Antimicrobial Peptides from Insect (Hermetia illucens) and Its Applications in the Food Packaging

About one-third of the total food produced is wasted, rising the concern to adopt proper management. Simultaneously with the increase in population, demand for food is increasing which may lead to scarcity. Adequate packaging is one of the ways to avoid deterioration of food and prevent wastage. In recent years, active packaging has attained interest due to its commendable results in food preservation. Several studies proved that the embodiment of antimicrobial components into the packaging material has the ability to prevent microbial contamination. Antimicrobial peptides (AMP) are newly discovered antimicrobial agents for impregnation into packaging material. Among various sources for AMP, insects have shown great resistivity against a wide spectrum of microorganisms. Insects feed on substances consisting of a varying range of contaminations, which often results in infections. Insects synthesise AMPs to fight such infections and survive in that atmosphere. The disease-causing agents in humans are the same as those found in insects. Hence, AMPs extracted from insects have the potential to fight the microorganisms that act as hazards to human health. This review highlights the harvesting and synthesis of AMPs from Hermetia illucens, which is a promising source for AMP and its applications in the food packaging industry.

Antimicrobial Peptides: Novel Source and Biological Function With a Special Focus on Entomopathogenic Nematode/Bacterium Symbiotic Complex

The rapid emergence of multidrug resistant microorganisms has become one of the most critical threats to public health. A decrease in the effectiveness of available antibiotics has led to the failure of infection control, resulting in a high risk of death. Among several alternatives, antimicrobial peptides (AMPs) serve as potential alternatives to antibiotics to resolve the emergence and spread of multidrug-resistant pathogens. These small proteins exhibit potent antimicrobial activity and are also an essential component of the immune system. Although several AMPs have been reported and characterized, studies associated with their potential medical applications are limited. This review highlights the novel sources of AMPs with high antimicrobial activities, including the entomopathogenic nematode/bacterium (EPN/EPB) symbiotic complex. Additionally, the AMPs derived from insects, nematodes, and marine organisms and the design of peptidomimetic antimicrobial agents that can complement the defects of therapeutic peptides have been used as a template.

Antimicrobial Peptides and Proteins: From Nature's Reservoir to the Laboratory and Beyond

Rapid rise of antimicrobial resistance against conventional antimicrobials, resurgence of multidrug resistant microbes and the slowdown in the development of new classes of antimicrobials, necessitates the urgent development of alternate classes of therapeutic molecules. Antimicrobial peptides (AMPs) are small proteins present in different lifeforms in nature that provide defense against microbial infections. They have been effective components of the host defense system for a very long time. The fact that the development of resistance by the microbes against the AMPs is relatively slower or delayed compared to that against the conventional antibiotics, makes them prospective alternative therapeutics of the future. Several thousands of AMPs have been isolated from various natural sources like microorganisms, plants, insects, crustaceans, animals, humans, etc. to date. However, only a few of them have been translated commercially to the market so far. This is because of some inherent drawbacks of the naturally obtained AMPs like 1) short half-life owing to the susceptibility to protease degradation, 2) inactivity at physiological salt concentrations, 3) cytotoxicity to host cells, 4) lack of appropriate strategies for sustained and targeted delivery of the AMPs. This has led to a surge of interest in the development of synthetic AMPs which would retain or improve the antimicrobial potency along with circumventing the disadvantages of the natural analogs. The development of synthetic AMPs is inspired by natural designs and sequences and strengthened by the fusion with various synthetic elements. Generation of the synthetic designs are based on various strategies like sequence truncation, mutation, cyclization and introduction of unnatural amino acids and synthons. In this review, we have described some of the AMPs isolated from the vast repertoire of natural sources, and subsequently described the various synthetic designs that have been developed based on the templates of natural AMPs or from de novo design to make commercially viable therapeutics of the future. This review entails the journey of the AMPs from their natural sources to the laboratory.

Evaluating the role of local host factors in the candidal colonization of oral cavity: A review update

Human oral cavity is home to a number of organisms, Candida albicans being one of them. This review article aims at understanding the correlation between the oral candidal colonization and the local host factors that may influence it with special emphasis on congenital craniofacial anomalies such as cleft lip and palate (CLP). Various scientific databases were searched online and relevant articles were selected based on the inclusion criteria. A comparative study was done to understand the interdependence of various factors (including CLP) and oral candidal colonization. The results revealed a strong association of certain local host factors which may influence the oral colonization of Candida species. Factors such as mucosal barrier, salivary constituents and quantity of saliva, congenital deformities like CLP, oral prostheses such as dentures/palatal obturators and fixed orthodontic appliances (FOAs) were identified. All these factors may directly affect the growth of Candida in the oral cavity. Although numerous studies have pointed a positive correlation between Oral Candidal colonization and local host factors such as oral prostheses, FOA, and oral mucosal barrier only one study has been done, in the Indian subcontinent with respect to the correlation of candidal colonization and CLP. After the evaluation of all the factors mentioned in various case studies, it can be concluded that the presence of local host factors such as orofacial clefts, dental prostheses, FOA, xerostomia, and atrophy of the oral mucous membrane lead to significant increase in candidal colonization, but since very few studies in regard to CLP have been done worldwide and in India, in particular, further studies are warranted.

The significance of α-defensins 1-3 in Behcet’s disease: a case-control study among Egyptian patients

Background

Behcet’s disease (BD) is associated with uveitis, oral ulcers, genital ulcers and arthritis. Enhanced activity of innate immunity components, such as neutrophils, natural killer (NK) cells and endothelial cells, is a prominent feature of BD. The aim of this study was to clarify the significance of α-defensins 1-3 in BD and detect their correlation with disease activity, severity and oral ulcer activity.

Results

Significant differences were found between Behcet’s patients and controls as regards serum α-defensins 1-3 (median 10.1, IQR 4–45 μg/ml versus median 7.4, IQR 0.6–13.2 μg/ml, p = 0.001) and salivary α-defensins 1-3 (median 17.4, IQR 5.7–44 μg/ml versus median 8.6, IQR 3.3–11 μg/ml, p < 0.001). Receiver operating characteristic (ROC) showed a fair area under curve (AUC) (AUC = 0.743), with sensitivity of 40% and specificity 100% at cutoff value of 17.3 μg/ml for serum α-defensins 1-3, while salivary α-defensins 1-3 showed excellent AUC (AUC = 0.936), with sensitivity of 93.3% and specificity of 86.7% at cutoff value of 9.8 μg/ml. The levels of serum and salivary α-defensins 1-3 > cutoff value were significantly higher in active severe Behcet’s patients with active oral ulcers (p < 0.001).

Conclusion

α-Defensins 1-3 may be involved in the pathogenesis of BD and could be valuable markers in the determination of disease activity, severity and oral ulcer activity.

Is the oral cavity a reservoir for prolonged SARS-CoV-2 shedding?

Limited knowledge about the contagiosity and case fatality rate of COVID-19 as well as the still enigmatic route of transmission have led to strict limitations of non-emergency health care especially in head and neck medicine and dentistry. There are theories that the oral cavity provides a favorable environment for SARS-CoV-2 entry and persistence which may be a risk for prolonged virus shedding. However, intraoral innate immune mechanisms provide antiviral effects against a myriad of pathogenic viruses. Initial hints of their efficacy against SARS-CoV-2 are surfacing. It is hypothesized that intraoral immune system activity modulates the invasion pattern of SARS-CoV-2 into oral cells. Thus, the significance of intraoral tissues for SARS-CoV-2 transmission and persistence cannot be assessed.

The underlying concept for this hypothesis was developed by the critical observation of a clinically asymptomatic COVID-19 patient. Despite a positive throat swab for SARS-CoV-2, molecular pathologic analysis of an oral perisulcular tissue specimen failed to detect SARS-CoV-2 RNA. More research effort is necessary to define the true origin of the contagiosity of asymptomatic COVID-19 patients.

Comparison of gingival crevicular fluid and serum human beta-defensin-2 levels between periodontal health and disease

BACKGROUND

The aim of this study was to evaluate the levels of serum and gingival crevicular fluid (GCF) human beta-defensin-2 (hBD-2), an antimicrobial peptide that takes roles in inflammatory diseases, in patients with chronic periodontitis (CP).

SUBJECTS AND METHODS

A total of one hundred and one individuals, 59 controls and 42 patients with CP, participated in this study. Clinical index measurements were recorded during the periodontal examination, and radiographic evaluation was also performed. The serum and gingival crevicular fluid (GCF) samples were taken from all of the participants, and the hBD-2 levels were determined biochemically by enzyme-linked immunosorbent assay (ELISA).

RESULTS

In our study, hBD-2 GCF levels in CP (stages II-IV periodontitis based on the new 2018 classification of periodontal diseases) group (2.77 ng/30 s) were higher than in the periodontally healthy (2.51 ng/30 s; p = .047) individuals. In contrast, serum hBD-2 levels in CP (2.92 ng/ml) were lower compared with those in healthy controls (7.75 ng/ml, p < .001).

CONCLUSION

Interestingly, our results showed that while higher hBD-2 GCF levels are associated with CP, lower serum hBD-2 levels were detected in CP.

Salivary human beta-defensins and cathelicidin levels in relation to periodontitis and type 2 diabetes mellitus

Objective: Type 2 diabetes mellitus (T2DM) is a well-defined risk factor of periodontitis and it can affect expression of human beta-defensins (hBDs) and cathelicidin (LL-37) as well. The aim of the present study was to evaluate the impact of periodontitis and T2DM on salivary concentrations of these antimicrobial peptides.Material and methods: Unstimulated saliva samples, together with full-mouth periodontal recordings were collected from 92 individuals with periodontitis (63 with T2DM and 21 smokers) and 86 periodontally healthy controls (58 with T2DM and 21 smokers). Salivary hBD-1, -2, -3, LL-37, and advanced glycalization end products (AGE) concentrations were measured by enzyme-linked immunosorbent assay.Results: Among the periodontitis patients, T2DM group demonstrated lower levels of hBD-1 (p = .006), hBD-2 (p < .001) and hBD-3 (p < .001), and higher levels of LL-37 (p < .001) compared to systemically healthy controls. When only periodontally healthy controls were included into the analysis, higher hBD-1 (p = .002) and LL-37 (p < .001) levels were found in T2DM patients in comparison to systemically healthy controls. Salivary LL-37 levels were associated with HbA1c and periodontitis, while hBD-2, hBD-3 and levels associated only with HbA1c.Conclusion: In the limits of this study, hyperglycaemia can be proposed as a regulator of salivary hBD and cathelicidin levels. Periodontitis, on the other hand, affects only salivary LL-37 levels.

Gingival tissue human beta-defensin levels in relation to infection and inflammation

AIM

To profile gingival tissue levels of human beta-defensin (hBD)-2 and hBD-3 in relation to gingival inflammation, Th17-related cytokine concentrations, Porphyromonas gingivalis counts, and gingipain and total protease activities.

MATERIALS AND METHODS

Gingival tissue and subgingival plaque samples were collected from 21 periodontitis patients including 48 periodontal pocket sites with marginal, mild, or moderate to severe inflammation. hBD levels were determined by immunodetection, P. gingivalis counts with real-time polymerase chain reaction, protease activities with fluorogenic substrates, and cytokine concentrations with Luminex technique. Data were statistically analysed using Kruskal-Wallis and Mann-Whitney U tests and Spearman correlation coefficients.

RESULTS

Subgingival plaque counts of P. gingivalis (p = .001) and gingipain activity (p < .001), as well as interleukin (IL)-1β (p = .012), IL-10 (p = .024), IL-17A (p = .002), IL-17F (p = .006), and IL-23 (p = .036) concentrations were elevated in severely inflamed sites, whereas no change was observed in hBD-2 and hBD-3 levels. Negative correlations were found between protease activity and hBD-2 (p = .033) and hBD-3(p = .003) levels.

CONCLUSIONS

Shift in gingival inflammation from marginal to mild stage is related to elevations in subgingival plaque P. gingivalis counts and gingipain activity, but not to tissue hBD levels. Negative correlations between hBDs and total protease activity suggest the degradation of these antimicrobial peptides in progressed inflammation.

Insect Antimicrobial Peptides, a Mini Review

Antimicrobial peptides (AMPs) are crucial effectors of the innate immune system. They provide the first line of defense against a variety of pathogens. AMPs display synergistic effects with conventional antibiotics, and thus present the potential for combined therapies. Insects are extremely resistant to bacterial infections. Insect AMPs are cationic and comprise less than 100 amino acids. These insect peptides exhibit an antimicrobial effect by disrupting the microbial membrane and do not easily allow microbes to develop drug resistance. Currently, membrane mechanisms underlying the antimicrobial effects of AMPs are proposed by different modes: the barrel-stave mode, toroidal-pore, carpet, and disordered toroidal-pore are the typical modes. Positive charge quantity, hydrophobic property and the secondary structure of the peptide are important for the antibacterial activity of AMPs. At present, several structural families of AMPs from insects are known (defensins, cecropins, drosocins, attacins, diptericins, ponericins, metchnikowins, and melittin), but new AMPs are frequently discovered. We reviewed the biological effects of the major insect AMPs. This review will provide further information that facilitates the study of insect AMPs and shed some light on novel microbicides.

Oral infection of mice with Fusobacterium nucleatum results in macrophage recruitment to the dental pulp and bone resorption

BACKGROUND

Fusobacterium nucleatum is a Gram-negative anaerobic bacterium associated with periodontal disease. Some oral bacteria, like Porphyromonas gingivalis, evade the host immune response by inhibiting inflammation. On the other hand, F. nucleatum triggers inflammasome activation and release of danger-associated molecular patterns (DAMPs) in infected gingival epithelial cells.

METHODS

In this study, we characterized the pro-inflammatory response to F. nucleatum oral infection in BALB/c mice. Western blots and ELISA were used to measure cytokine and DAMP (HMGB1) levels in the oral cavity after infection. Histology and flow cytometry were used to observe recruitment of immune cells to infected tissue and pathology.

RESULTS

Our results show increased expression and production of pro-inflammatory cytokines during infection. Furthermore, we observe that F. nucleatum infection leads to recruitment of macrophages in different tissues of the oral cavity. Infection also contributes to osteoclast recruitment, which could be involved in the observed bone resorption.

CONCLUSIONS

Overall, our findings suggest that F. nucleatum infection rapidly induces inflammation, release of DAMPs, and macrophage infiltration in gingival tissues and suggest that osteoclasts may drive bone resorption at early stages of the inflammatory process.

Host defense peptides: An insight into the antimicrobial world

A serious challenge to antimicrobial therapies has emerged due to rapid increase in drug-resistant infections creating an urge for the development of alternative therapeutics. Antimicrobial peptides (AMPs) have gained importance because of their broad-spectrum antimicrobial activities and mediator-like functions linking innate and adaptive immune responses. The multidimensional properties of these peptides hold promising potentials as prophylactic and antimicrobial agents. This review discusses various AMPs and their role in combating microorganisms and infections along with its clinical implication.

Human beta defensin-1 is involved in the susceptibility to adeno-tonsillar hypertrophy

INTRODUCTION

Innate immunity molecules are known to play a pivotal role in the homeostasis of the oral mucosa, permitting the presence of commensal microflora and, at the same time, providing a first line of defense against pathogens attempting to invade the oral cavity. Tonsils represent the local immune tissue in oral cavity, being able to provide a non-specific response to pathogens; however, in the presence of microbes or foreign materials present in the mouth tonsils could became infected and develop chronic inflammation, thus leading to hypertrophy. The etiology of the disease is multifactorial depending upon environmental and host factors, the latter including molecules of mucosal innate immunity.

METHODS

Ninety-five children with adeno-tonsillar hypertrophy subjected to adeno-tonsillectomy were recruited at the pediatric otorhinolaryngology service of the Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste (Italy). The specimen discarded from the surgery were used for genomic DNA extraction and genotyping, for mRNA extraction and gene expression analysis, finally the samples were cut and used to prepare slides to perform immunohistochemistry.

RESULTS

Functional polymorphisms within DEFB1 gene, encoding the human beta defensin-1 (hBD-1), were analyzed finding association between DEFB1 rare haplotypes and susceptibility to adeno-tonsillar hypertrophy. DEFB1 mRNA expression was detected in the tonsils and the hBD-1 protein was localized at the epithelia of tonsils mainly in the proximity of the basal lamina.

CONCLUSION

Our findings lead us to hypothesize an involvement of hBD-1 mediated innate immunity in the modulation of the susceptibility towards adeno-tonsillar hypertrophy development.

Human β-defensin 3-combined gold nanoparticles for enhancement of osteogenic differentiation of human periodontal ligament cells in inflammatory microenvironments

Objective

It is a great challenge to absorb and conduct biophysicochemical interactions at the nano-bio interface. Peptides are emerging as versatile materials whose function can be programmed to perform specific tasks. Peptides combined nanoparticles might be utilized as a new approach of treatment. Human β-defensin 3 (hBD3), possesses both antimicrobial and proregeneration properties. Gold nanoparticles (AuNPs) have shown promising applications in the field of tissue engineering. However, the coordinating effects of AuNPs and hBD3 on human periodontal ligament cells (hPDLCs) remain unknown. In this study, we systematically investigated whether AuNPs and hBD3 would be able to coordinate and enhance the osteogenic differentiation of hPDLCs in inflammatory microenvironments, and the underlying mechanisms was explored.

Methods

hPDLCs were stimulated with E. coli-LPS, hBD3 and AuNPs. Alkaline phosphatase (ALP) and alizarin red S staining were used to observe the effects of hBD3 and AuNPs on the osteogenic differentiation of hPDLCs. Real-time PCR and western blot were performed to evaluate the osteogenic differentiation and Wnt/β-catenin signaling pathway related gene and protein expression.

Results

In the inflammatory microenvironments stimulated by E. coli-LPS, we found that AuNPs and hBD3 increased the proliferation of hPDLCs slightly. In addition, hBD3-combined AuNPs could significantly enhance ALP activities and mineral deposition in vitro. Meanwhile, we observed that the osteogenic differentiation-related gene and protein expressions of ALP, collagenase-I (COL-1) and runt-related transcription factor 2 (Runx-2) were remarkably upregulated in the presence of hBD3 and AuNPs. Moreover, hBD3-combined AuNPs strongly activated the Wnt/β-catenin signaling pathway and upregulated the gene and protein expression of β-catenin and cyclin D1. Furthermore, hBD3-combined AuNPs induced osteogenesis, which could be reversed by the Wnt/β-catenin signaling pathway inhibitor (ICG-001).

Conclusion

The present study demonstrated that hBD3 combined AuNPs could significantly promote the osteogenic differentiation of hPDLCs in inflammatory microenvironments via activating the Wnt/β-catenin signaling pathway.

Effect of soft foods on primary human gingival epithelial cell growth and the wound healing process

OBJECTIVES

Investigate the effect of soft diet foods on gingival epithelial cell growth, migration, and mediator secretion.

METHODS

Human gingival epithelial cells were stimulated for various time periods with the following soft diet foods: orange juice, drinkable yogurt, and a nutritional drink. Cell growth was determined by an MTT assay and cell migration was investigated by a scratch assay and F-actin filament staining. Keratin production was analyzed by Western blot and wound healing mediators IL-6 and human β-defensin 2 were quantified by ELISA.

RESULTS

We demonstrate, for the first time, that certain soft diet foods increased the production of keratin 5, 14, and 19 by gingival epithelial cells. These proteins were known to be produced by proliferating cells. The soft foods tested also stimulated gingival epithelial cells to produce IL-6 and human β-defensin 2. Soft foods are capable of promoting gingival epithelial cell migration by increasing F-actin production, which is part of the wound healing process. Results varied depending on the foods tested.

CONCLUSION

Gingival epithelial cells interacted with the soft diet foods under study. This interaction was shown to upregulate keratin expression, as well as IL-6 and human β-defensin 2 secretions. Furthermore, following cell wound, the soft foods upregulated post-scratch cell migration and F-actin production. Overall data suggest that the choice of foods in soft diets following oral surgery may influence the wound healing process of gingival epithelial cells.

Oral antimicrobial peptides: Types and role in the oral cavity

Antimicrobial peptides (AMPs) are a wide-ranging class of host-defense molecules that act early to contest against microbial invasion and challenge. These are small cationic peptides that play an important in the development of innate immunity. In the oral cavity, the AMPs are produced by the salivary glands and the oral epithelium and serve defensive purposes. The aim of this review was to discuss the types and functions of oral AMPs and their role in combating microorganisms and infections in the oral cavity.

FAD-I, a Fusobacterium nucleatum Cell Wall-Associated Diacylated Lipoprotein That Mediates Human Beta Defensin 2 Induction through Toll-Like Receptor-1/2 (TLR-1/2) and TLR-2/6

We previously identified a cell wall-associated protein from Fusobacterium nucleatum, a Gram-negative bacterium of the oral cavity, that induces human beta defensin 2 (hBD-2) in primary human oral epithelial cells (HOECs) and designated it FAD-I (Fusobacterium-associated defensin inducer). Here, we report differential induction of hBD-2 by different strains of F. nucleatum; ATCC 25586 and ATCC 23726 induce significantly more hBD-2 mRNA than ATCC 10953. Heterologous expression of plasmid-borne fadI from the highly hBD-2-inducing strains in a ΔfadI mutant of ATCC 10953 resulted in hBD-2 induction to levels comparable to those of the highly inducing strains, indicating that FAD-I is the principal F. nucleatum agent for hBD-2 induction in HOECs. Moreover, anti-FAD-I antibodies blocked F. nucleatum induction of hBD-2 by more than 80%. Recombinant FAD-I (rFAD-I) expressed in Escherichia coli triggered levels of hBD-2 transcription and peptide release in HOECs similar to those of native FAD-I (nFAD-I) isolated from F. nucleatum ATCC 25586. Tandem mass spectrometry revealed a diacylglycerol modification at the cysteine residue in position 16 for both nFAD-I and rFAD-I. Cysteine-to-alanine substitution abrogated FAD-I's ability to induce hBD-2. Finally, FAD-I activation of hBD-2 expression was mediated via both Toll-like receptor-1/2 (TLR-1/2) and TLR-2/6 heterodimerization. Microbial molecules like FAD-I may be utilized in novel therapeutic ways to bolster the host innate immune response at mucosal surfaces.

Salivary Antimicrobial Peptides in Early Detection of Periodontitis

In the pathogenesis of periodontitis, an infection-induced inflammatory disease of the tooth-supporting tissues, there is a complex interaction between the subgingival microbiota and host tissues. A periodontal diagnostic tool for detecting the initiation and progression of the disease, monitoring the response to therapy, or measuring the degree of susceptibility to future disease progression has been of interest for a long time. The value of various enzymes, proteins, and immunoglobulins, which are abundant constituents of saliva, as potential biomarkers has been recognized and extensively investigated for periodontal diseases. Gingival defensins and cathelicidins are small cationic antimicrobial peptides that play an important role in innate immune response. However, their applicability as salivary biomarkers is still under debate. The present review focuses on proteomic biomarkers and antimicrobial peptides, in particular, to be used at early phases of periodontitis.

Overexpressions of hBD-2, hBD-3, and hCAP18/LL-37 in Gingiva of Diabetics with Periodontitis

Antimicrobial peptides of the epithelium play a significant role in the innate immune response in the oral cavity, which is constantly exposed to microbes. Type 2 diabetes mellitus (T2DM) is a highly prevalent metabolic disease which is related to periodontal disease. To date, little is known about expressions of antimicrobial peptides in gingival epithelia of diabetics. Our aim was to examine the expression and localization of human beta-defensins (hBD)-2 and -3 and cathelicidin (hCAP18/LL-37) in diabetic subjects suffering from generalized periodontitis (GP). Gingival tissue sections were collected from three subject groups: 14 T2DM subjects with GP (T2DM+GP), 11 systemically healthy GP patients (GP), and 13 systemically and periodontally healthy subjects (control). Surgical incisions targeted the sulcular epithelium and/or the bottom of the selected periodontal pocket. Tissue specimens were fixed in paraformaldehyde and embedded in paraffin blocks. Immunohistochemistry stainings were performed for cytokeratin19, hBD-2, hBD-3 and hCAP18/LL-37. Stainings were examined under light microscope with 40× magnification. Results were statistically evaluated by the t-test. In controls, hBD-2 was localized at the superficial layers of the gingival epithelium, hBD-3 and hCAP18/LL-37 were at the basal layers, whereas in subjects with periodontitis both defensins were visible at all epithelial layers. hBD-2 was detected in the nucleus and cytoplasm, while hBD-3 and hCAP18/LL-37 were detected only in the cytoplasm of the cells. Expressions of hBD-2 (p=0.005), hBD-3 (p=0.007), and hCAP18/LL-37 (p=0.002) were elevated in subjects with T2DM+GP in comparison to controls. No statistically significant difference was found in the expression of hBD-2, -3, and hCAP18/LL-37 between the GP group and the control or T2DM+GP groups. Gingival antimicrobial peptides are overexpressed in T2DM. This outcome can be part of impaired immune response in diabetics, and underlying factors and mechanisms need to be elucidated.

The mucosal immune system in the oral cavity-an orchestra of T cell diversity

The mucosal immune system defends against a vast array of pathogens, yet it exhibits limited responses to commensal microorganisms under healthy conditions. The oral-pharyngeal cavity, the gateway for both the gastrointestinal and respiratory tracts, is composed of complex anatomical structures and is constantly challenged by antigens from air and food. The mucosal immune system of the oral-pharyngeal cavity must prevent pathogen entry while maintaining immune homeostasis, which is achieved via a range of mechanisms that are similar or different to those utilized by the gastrointestinal immune system. In this review, we summarize the features of the mucosal immune system, focusing on T cell subsets and their functions. We also discuss our current understanding of the oral-pharyngeal mucosal immune system.

Defensins and LL-37: a review of function in the gingival epithelium

Antimicrobial peptides represent an important aspect of the innate defense system that contributes to the control of bacterial colonization and infection. As studies have progressed it has become clear that antimicrobial peptides manifest other functions in addition to their antimicrobial effects. These functions include chemotaxis of numerous types of host cells involved in both the innate and adaptive immune responses. In this review, the antimicrobial activity, the regulation and the contribution to host homeostasis of alpha-defensins and LL-37, as well as of beta-defensins, are discussed in the context of their specific tissue locations in the junctional epithelium and oral epithelium, respectively.

Salivary levels of HNP 1-3 are related to oral ulcer activity in Behçet's disease

BACKGROUND

Saliva contains antimicrobial peptides derived from oral epithelium as well as neutrophils in the innate immune response. The aim of this study was to examine the association between salivary human neutrophil peptide (HNP) 1-3 levels originating from neutrophils and oral ulcers in patients with Behçet's disease (BD).

METHODS

Ninety-five patients with BD (F/M: 39/56; mean age: 38.7 ± 11.9 years) and 53 healthy controls (HC; F/M: 23/30; mean age: 35.2 ± 10.1 years) were included in the study. The disease control group (F/M: 20/33; mean age: 33.7 ± 10.7 years) was comprised of patients with oral infection regarding endodontic infection (n = 32) and pericoronitis (n = 21). Salivary HNP 1-3 levels of groups were measured in unstimulated samples by ELISA (Hycult, the Netherlands).

RESULTS

A statistically significant increase was found in salivary HNP 1-3 levels of patients with BD (2268.28 ± 1216.38 μg/ml) compared with HC (1836.49 ± 857.76 μg/ml), patients with endodontic infection (849.9 ± 376.1 μg/ml), and patients with pericoronitis (824.3 ± 284.02 μg/ml; P = 0.024, 0.000 and 0.000, respectively). The ratio of active oral ulcer (100%, n = 14) was higher in low HNP 1-3 levels (≤ 1000 μg/ml) than the others (66.7%, n = 54) in active patients with BD (P = 0.008). Moreover, salivary HNP 1-3 levels were significantly lower in patients with endodontic infection and patients with pericoronitis compared with those in the HC group and patients with BD (P = 0.000).

CONCLUSION

A decrease in salivary HNP 1-3 levels might be a biological factor for predisposition to oral ulcers in patients with BD and oral infection in healthy patients.

Antimicrobial peptide control of pathogenic microorganisms of the oral cavity: a review of the literature

Antimicrobial peptides, molecules produced in many different organisms, have high biocidal activity against several microorganisms. However, several questions about these molecules remain unclear. Therefore, this report details a systematic survey of the literature on the use of antimicrobial peptides against oral pathogens and indicates which peptides and microorganisms are most extensively studied. Articles were located using the PubMed and Science Direct databases with the following inclusion criteria: publication date between 2002 and 2011; keywords "biofilm OR biological film OR biological layer OR bacterial growth" AND "peptide" AND "oral cavity OR mouth OR buccal mucosa OR oral mucosa OR mouth mucosa"; and abstract in English. A total of 73 articles were selected after refinement of the data. An increase in publications focusing on the use of antimicrobial peptides against oral microorganisms was observed. In addition, the peptides produced by cells of the oral mucosa (defensins, LL-37 and histatins) as well as Streptococcus mutans (among cariogenic bacteria) and Porphyromonas gingivalis (among periodontal bacteria) were the most studied subjects. It was concluded that the use of antimicrobial peptides as a tool for microbial control is of increasing importance, likely due to its widespread use, mechanism of action, and low rates of bacterial resistance.

Understanding the roles of gingival beta-defensins

Gingival epithelium produces β-defensins, small cationic peptides, as part of its contribution to the innate host defense against the bacterial challenge that is constantly present in the oral cavity. Besides their functions in healthy gingival tissues, β-defensins are involved in the initiation and progression, as well as restriction of periodontal tissue destruction, by acting as antimicrobial, chemotactic, and anti-inflammatory agents. In this article, we review the common knowledge about β-defensins, coming from in vivo and in vitro monolayer studies, and present new aspects, based on the experience on three-dimensional organotypic culture models, to the important role of gingival β-defensins in homeostasis of the periodontium.

Salivary levels of antimicrobial peptides Hnp 1-3, Ll-37 and S100 in Behcet's disease

BACKGROUND

Oral ulcer is the cardinal clinical sign and increased neutrophilic activity is a part of the pathogenesis in Behcet's disease (BD). Saliva, as a part of the innate immune response, contains antimicrobial peptides (AMPs) that are derived from both oral epithelial cells and neutrophils. The aim of this study was to investigate the associations between salivary levels of AMPs HNP 1-3, LL-37 and S100 and disease course in patients with Behcet's disease (BD).

METHODS

Fifty-three patients with BD and 44 healthy controls (HC) were included in the study. Disease severity score reflecting organ involvement was calculated. Salivary HNP 1-3, LL-37 and S100 levels were measured in unstimulated saliva samples by ELISA.

RESULTS

Salivary HNP 1-3 and S100 levels in BD patients (2715.2 ± 1333.4 μg/ml and 430.6 ± 203.9 ng/ml) were significantly higher compared to HC (1780.6 ± 933.2 μg/ml and 365.3 ± 84.7 ng/ml) (p = 0.000 and p = 0.004, respectively). Although LL-37 levels were also higher in BD than HC (190.9 ± 189.1 vs 143.1 ± 128.9 ng/ml), no significant difference was observed (p = 0.53). Salivary HNP 1-3 and LL-37 levels were associated with the severity of BD (mild disease: 1975.1 ± 1174.2 μg/ml and 115.9 ± 109.4 ng/ml vs severe disease: 2955.7 ± 1305.6 μg/ml and 215.3 ± 203.8 ng/ml, p=0.020 and p=0.031, respectively). Salivary LL-37 levels also correlated with the number of monthly oral ulcers (r = 0.5 p = 0.000).

CONCLUSION

An increase in salivary HNP 1-3 and S100 levels might be associated with enhanced local and systemic innate responses in BD.

Development of mucosal immunity in children: a rationale for sublingual immunotherapy?

The mucosal immune system has bidirectional tasks to mount an effective defense against invading harmful pathogens and to suppress the immune response to alimentary antigens and commensal bacterial flora. Oral tolerance is a suppression of the mucosal immune pathway related to a specific immunophenotype of the dendritic cells and an induction of the regulatory T cells as well as with the silencing of the effector T cell response by anergy and deletion. The physiological dynamic process of the anatomical and functional maturation of the immune system occurring in children during pre- and postnatal periods is a significant factor, having an impact on the fine balance between the activation and the suppression of the immune response. In this paper, mechanisms of mucosal immunity and tolerance induction in terms of maturational issues are discussed with a special emphasis on the implications for a novel therapeutic intervention in allergic diseases via the sublingual route.

A review of the role of solar ultraviolet-B irradiance and vitamin D in reducing risk of dental caries

Large geographical variations in dental health and tooth loss among US adolescents and young adults have been reported since the mid-1800s. Studies in the 1920s and 1930s noted that vitamin D and ultraviolet-B (UVB) irradiance reduced caries formation, the proposed mechanism being improved calcium absorption and metabolism. This paper reviews the history of studies of dental caries with respect to vitamin D, geographical location and available solar UVB doses. In addition, data on mean dental health rank by state for US servicemen from three periods, 1918, 1934 and 1943, were used in regression analyses with respect to summertime solar UVB doses and an index for mottled enamel, a proxy for natural fluoridation of drinking water, for 1935. There was a significant inverse correlation for dental health rank with respect to solar UVB from doses of 4.0 to 6.5 kJ/m(2) with little change thereafter. Adding data for mottled enamel rates for the states with UvB doses <6.6 kJ/m(2) improved the adjusted R(2) from 0.45 to 0.52. The mechanism whereby UVB reduces risk of dental caries is likely through production of vitamin D, followed by induction of cathelicidin and defensins, which have antimicrobial properties. Serum 25-hydroxyvitamin D concentrations at or above 30-40 ng/ml should significantly reduce the formation of dental caries. It is unfortunate that the UVB and vitamin D findings were not given more consideration in the 1950s as a way to reduce the risk of dental caries when water fluoridation was being proposed.