Beta-defensins: what are they really doing in the oral cavity?

Systemic Factors Effecting Human Beta-Defensins in Oral Cavity

Human beta-defensins are host defense peptides with broad antimicrobial and inflammatory functions. In the oral cavity, these peptides are produced mainly by the keratinocytes of the epithelium; however, fibroblasts, monocytes, and macrophages also contribute to oral human beta-defensin expressions. The resident and immune cells of the oral cavity come into contact with various microbe-associated molecular patterns continuously and simultaneously. The overall antimicrobial cellular response is highly influenced by local and environmental factors. Recent studies have produced evidence showing that not only systemic chronic diseases but also systemic factors like hyperglycemia, pregnancy, the long-term use of certain vitamins, and aging can modulate oral cellular antimicrobial responses against microbial challenges. Therefore, the aim of this narrative review is to discuss the role of systemic factors on oral human beta-defensin expressions.

Human β-Defensins in Diagnosis of Head and Neck Cancers

Head and neck cancers are malignant growths with high death rates, which makes the early diagnosis of the affected patients of utmost importance. Over 90% of oral cavity cancers come from squamous cells, and the tongue, oral cavity, and salivary glands are the most common locations for oral squamous cell carcinoma lesions. Human β-defensins (hBDs), which are mainly produced by epithelial cells, are cationic peptides with a wide antimicrobial spectrum. In addition to their role in antimicrobial defense, these peptides also take part in the regulation of the immune response. Recent studies produced evidence that these small antimicrobial peptides are related to the gene and protein expression profiles of tumors. While the suppression of hBDs is a common finding in head and neck cancer studies, opposite findings were also presented. In the present narrative review, the aim will be to discuss the changes in the hBD expression profile during the onset and progression of head and neck cancers. The final aim will be to discuss the use of hBDs as diagnostic markers of head and neck cancers.

Investigation of human β-defensins 1, 2 and 3 in human saliva by molecular dynamics

Human β-defensins present in saliva have a broad spectrum of antimicrobial activities that work against infections in oral cavity. To provide a better understanding of these molecules' properties and functions at the molecular level, we have investigated and compared the important structural properties of human β-defensin-1, -2 and -3 using molecular dynamics simulations. Our results have shown that human β-defensin-3 has a more flexible structure in water than the other two because of its high hydrophilicity, low β-sheet content and high repulsive forces between its charged residues. Moreover, we found that the location of the salt bridges is important in protein's stability in water. Molecular dynamics simulations of human β-defensins 1, 2 and 3 revealed that the hbd-3 is more flexible in water than hbd-1 and hbd-2.

β-defensinas como posibles indicadores de la actividad inflamatoria en la enfermedad periodontal

Periodontal disease (gingivitis and periodontitis) is an inflam-matory process caused by the activity of pathogenic bacteria and their products on the gingival sulcus, with the consequent activation of the immune response. Saliva and crevicular fluid contain a wide variety of enzymes and antimicrobial factors that are in contact with the supragingival and subgingival region, in-cluding β-defensins (hBDs). hHBDs are non-glycosylated, cysteine-rich cationic peptides produced by epithelial cells with antimicrobial and immunoregulatory effects, thus contributing to maintaining homeostasis in periodontal tissues. The changes in the microbiota and the immune response from a healthy peri-odontium to gingivitis and, finally, to periodontitis are complex. Their sever-ity depends on a dynamic balance between bacteria associated with plaque, genetic and environmental factors. Recent advances have made it possible to understand the implication of hBDs in the detection, diagnosis, and therapy of periodontal disease and the relationship between periodontitis and other inflammatory conditions. This review aims to describe the effect of hBDs on the immune response and its use as a possible marker of the inflammatory activity of the periodontal disease.

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.

HBD-2 binds SARS-CoV-2 RBD and blocks viral entry: Strategy to combat COVID-19

New approaches to complement vaccination are needed to combat the spread of SARS-CoV-2 and stop COVID-19-related deaths and medical complications. Human beta defensin 2 (hBD-2) is a naturally occurring epithelial cell-derived host defense peptide that has anti-viral properties. Our comprehensive in-silico studies demonstrate that hBD-2 binds the site on the CoV-2-RBD that docks with the ACE2 receptor. Biophysical measurements confirm that hBD-2 indeed binds to the CoV-2-receptor-binding domain (RBD) (KD ∼ 2μM by surface plasmon resonance), preventing it from binding to ACE2-expressing cells. Importantly, hBD-2 shows specificity by blocking CoV-2/spike pseudoviral infection, but not VSVG-mediated infection, of ACE2-expressing human cells with an IC50 of 2.8 ± 0.4 μM. These promising findings offer opportunities to develop hBD-2 and/or its derivatives and mimetics to safely and effectively use as agents to prevent SARS-CoV-2 infection.

Oral Cavity and Candida albicans: Colonisation to the Development of Infection

Candida colonisation of the oral cavity increases in immunocompromised individuals which leads to the development of oral candidiasis. In addition, host factors such as xerostomia, smoking, oral prostheses, dental caries, diabetes and cancer treatment accelerate the disease process. Candida albicans is the primary causative agent of this infection, owing to its ability to form biofilm and hyphae and to produce hydrolytic enzymes and candialysin. Although mucosal immunity is activated, from the time hyphae-associated toxin is formed by the colonising C. albicans cells, an increased number and virulence of this pathogenic organism collectively leads to infection. Prevention of the development of infection can be achieved by addressing the host physiological factors and habits. For maintenance of oral health, conventional oral hygiene products containing antimicrobial compounds, essential oils and phytochemicals can be considered, these products can maintain the low number of Candida in the oral cavity and reduce their virulence. Vulnerable patients should be educated in order to increase compliance.

Human beta-defensin-1 rs2738047 polymorphism is associated with shisha smoking risk among Saudi population

Human β-defensin (HBD), a member of the antimicrobial peptides, is essential for respiratory epithelial cells' microbial defense, and is affected by cigarette smoking (CS). Its expression is upregulated by stimulation from microbes or inflammation. Genetic polymorphisms in the HBD-1 gene have been implicated in the development of various smoking-related diseases, including chronic obstructive pulmonary disease and asthma. Thus, we sought to analyze possible associations between HBD-1 single-nucleotide polymorphism (SNP) in HBD-1 gene and CS in ethnic Saudi Arabian subjects. Variants rs1047031 (C/T), rs1799946 (C/T), rs2738047 (C/T), and rs11362 (C/T) were investigated by genotyping 575 blood specimens from males and females, smokers/non-smokers: 288/287. The CT and CT+TT genotypes of rs1799946 presented an ~5-fold increased correlation with CS among the female smokers, compared with the female controls (OR = 5.473, P = 0.02003; and OR = 5.211, P = 0.02028, respectively), an observation similar to rs11362 SNP in female smokers, but with protective effects in TT genotype, compared with the CC reference allele (OR = 0.143, P = 0.04368). In shisha smokers, the heterozygous CT and the CT/TT genotype of rs2738047 polymorphism showed the same results with ~3-fold increased correlation with CS (OR = 2.788; P = 0.03448), compared with the cigarette smokers category. No significant association was shown in genotypic distributions and allelic frequencies of rs1047031. Further investigations, including large study samples, are required to investigate the effects of shisha on human beta-defensin expression and protein levels.

Molecular dynamics simulations and functional studies reveal that hBD-2 binds SARS-CoV-2 spike RBD and blocks viral entry into ACE2 expressing cells

New approaches to complement vaccination are needed to combat the spread of SARS-CoV-2 and stop COVID-19 related deaths and long-term medical complications. Human beta defensin 2 (hBD-2) is a naturally occurring epithelial cell derived host defense peptide that has antiviral properties. Our comprehensive in-silico studies demonstrate that hBD-2 binds the site on the CoV-2-RBD that docks with the ACE2 receptor. Biophysical and biochemical assays confirm that hBD-2 indeed binds to the CoV-2-receptor binding domain (RBD) (KD ~ 300 nM), preventing it from binding to ACE2 expressing cells. Importantly, hBD-2 shows specificity by blocking CoV-2/spike pseudoviral infection, but not VSV-G mediated infection, of ACE2 expressing human cells with an IC50 of 2.4± 0.1 μM. These promising findings offer opportunities to develop hBD-2 and/or its derivatives and mimetics to safely and effectively use as novel agents to prevent SARS-CoV-2 infection.

Bio- and Nanotechnology as the Key for Clinical Application of Salivary Peptide Histatin: A Necessary Advance

Candida albicans is a common microorganism of human’s microbiota and can be easily found in both respiratory and gastrointestinal tracts as well as in the genitourinary tract. Approximately 30% of people will be infected by C. albicans during their lifetime. Due to its easy adaptation, this microorganism started to present high resistance to antifungal agents which is associated with their indiscriminate use. There are several reports of adaptive mechanisms that this species can present. Some of them are intrinsic alteration in drug targets, secretion of extracellular enzymes to promote host protein degradation and efflux receptors that lead to a diminished action of common antifungal and host’s innate immune response. The current review aims to bring promising alternatives for the treatment of candidiasis caused mainly by C. albicans. One of these alternatives is the use of antifungal peptides (AFPs) from the Histatin family, like histatin-5. Besides that, our focus is to show how nanotechnology can allow the application of these peptides for treatment of this microorganism. In addition, our intention is to show the importance of nanoparticles (NPs) for this purpose, which may be essential in the near future.

Daily Consumption of an Anthocyanin-Rich Extract Made From New Zealand Blackcurrants for 5 Weeks Supports Exercise Recovery Through the Management of Oxidative Stress and Inflammation: A Randomized Placebo Controlled Pilot Study

Background: Regular exercise is essential to a healthy lifestyle but evokes an oxidative and inflammatory stress. Depending upon its intensity and duration this can result in either beneficial adaptive changes or underlying tissue damage that impacts upon long-term health and individual sporting training schedules. Functional foods containing plant bioactives have potential to support exercise through management of the detrimental aspects of exercise and complement ergonomic adaptive benefits. Aim: Previously we reported that a single consumption of a 3.2 mg/kg New Zealand blackcurrant anthocyanin-rich extract (BAE) 1 h before a 30 min rowing exercise attenuated moderate exercise-mediated oxidative stress and supported innate immunity. Here we evaluate whether the efficacy of a single consumption of BAE 1 h prior to exercise is changed after extended daily BAE consumption for 5 weeks. Results: On week 1, a single consumption of BAE 1 h before a 30 min row mediated a significant (p < 0.05) 46% reduction in post-exercise-induced malondialdehyde (MDA) by 2 h compared to a 30% reduction in the placebo group. Similar efficacy was observed 5 weeks later after daily consumption of BAE. In addition, daily BAE consumption for 5 weeks improved the efficacy to (a) resolve acute inflammation, and (b) increased plasma IL-10, salivary beta-defensin 2 (BD2) and secretory IgA. Although no change in plasma antioxidant capacity was detected, a significant (p < 0.009) positive correlation between plasma IL-10 and plasma antioxidant capacity (R 2 = 0.35) was observed on week 6 after 5 week BAE consumption suggesting IL-10 influences antioxidant properties. Using a differentiated myotubule cell-line revealed that whilst IL-10 had no direct antioxidant neutralizing action, longer-term exposure (24 h) attenuated 2,2'-Azobis(2-amidinopropane) dihydrochloride (AAPH)-induced myotubule oxidative stress, supporting a putative role for IL-10 in the modulation of cellular antioxidant systems. Conclusions: Daily consumption of BAE for 5 weeks serves to enhance the exercise recovery effectiveness of a single consumption of BAE and promotes beneficial/protective antioxidant/anti-inflammatory cellular events that facilitate exercise recovery.

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.

Human Beta Defensins and Cancer: Contradictions and Common Ground

Human beta-defensins (hBDs, −1, 2, 3) are a family of epithelial cell derived antimicrobial peptides (AMPs) that protect mucosal membranes from microbial challenges. In addition to their antimicrobial activities, they possess other functions; e.g., cell activation, proliferation, regulation of cytokine/chemokine production, migration, differentiation, angiogenesis, and wound healing processes. It has also become apparent that defensin levels change with the development of neoplasia. However, inconsistent observations published by various laboratories make it difficult to reach a consensus as to the direction of the dysregulation and role the hBDs may play in various cancers. This is particularly evident in studies focusing on oral squamous cell carcinoma (OSCC). By segregating each hBD by cancer type, interrogating methodologies, and scrutinizing the subject cohorts used in the studies, we have endeavored to identify the “take home message” for each one of the three hBDs. We discovered that (1) consensus-driven findings indicate that hBD-1 and−2 are down- while hBD-3 is up-regulated in OSCC; (2) hBD dysregulation is cancer-type specific; (3) the inhibition/activation effect an hBD has on cancer cell lines is related to the direction of the hBD dysregulation (up or down) in the cancer from which the cell lines derive. Therefore, studies addressing hBD dysregulation in various cancers are not generalizable and comparisons should be avoided. Systematic delineation of the fate and role of the hBDs in a specific cancer type may lead to innovative ways to use defensins as prospective biomarkers for diagnostic/prognostic purposes and/or in novel therapeutic modalities.

Candida albicans Interactions with Mucosal Surfaces during Health and Disease

Flexible adaptation to the host environment is a critical trait that underpins the success of numerous microbes. The polymorphic fungus Candida albicans has evolved to persist in the numerous challenging niches of the human body. The interaction of C. albicans with a mucosal surface is an essential prerequisite for fungal colonisation and epitomises the complex interface between microbe and host. C. albicans exhibits numerous adaptations to a healthy host that permit commensal colonisation of mucosal surfaces without provoking an overt immune response that may lead to clearance. Conversely, fungal adaptation to impaired immune fitness at mucosal surfaces enables pathogenic infiltration into underlying tissues, often with devastating consequences. This review will summarise our current understanding of the complex interactions that occur between C. albicans and the mucosal surfaces of the human body.

Tainted air: The link between pollution and Alzheimer's disease

In this issue of the Biomedical Journal, we learn how air pollution may contribute to cognitive decline and even increase risk for Alzheimer's disease. We also highlight original research documenting the body's response to infection with a common oral pathogen. Finally, we learn how a cellular antioxidant protein protects against mitochondrial dysfunction in Parkinson's disease.

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.

Stress-related salivary proteins affect the production of volatile sulfur compounds by oral bacteria

OBJECTIVE

To determine whether stress-related substances and sex hormones influence the growth and in vitro production of volatile sulfur compounds (VSCs) by Solobacterium moorei and Fusobacterium nucleatum.

MATERIALS AND METHODS

Bacteria growth and VSCs production were evaluated in the presence of alpha-amylase, beta-defensin-2, mucin, estradiol, and progesterone. Growth was evaluated by colony counting, and the production of the VSCs hydrogen sulfide (H₂ S) and methyl mercaptan (CH₃ SH) was measured using the Oral Chroma™ instrument.

RESULTS

Mucin induced the production of H₂ S by both bacteria, but had a slight inhibitory effect on CH₃ SH production by F. nucleatum. It also increased the viability of F. nucleatum. Alpha-amylase increased H₂ S production by S. moorei and CH₃ SH production by F. nucleatum, but had no effect on H₂ S production by F. nucleatum. No substance altered the viability of S. moorei. No effects of beta-defensin-2, estradiol, or progesterone were observed.

CONCLUSION

The salivary stress-related proteins mucin and alpha-amylase altered VSCs production by F. nucleatum and S. moorei, favoring H₂ S production. These findings are a step toward understanding the relation between stress and increased amounts of H₂ S.

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.

The Anti-inflammatory Effects of Glycerol-supplemented Probiotic Lactobacillus reuteri on Infected Epithelial cells In vitro

Background:

One of the most interesting effects of probiotics is their ability to modulate the immune system through the induction of cytokines and to enhance the host immune response.

Aims:

The purpose of this study was to evaluate the anti-inflammatory effect of glycerol-supplemented Lactobacillus reuteri on the transcription level of interleukin (IL)-8 and human-beta-defensin (hBD)-2 expressed by epithelial cells after exposure to bacteria.

Materials and Methods:

The confluent-cultured HaCat cell line (10⁵ cells/mL) was exposed to Streptococcus mutans ATCC-25175 and Porphyromonas gingivalis ATCC-33277 (10⁷ colony-forming units [CFU]/mL) for 24 h and challenged with probiotic L. reuteri ATCC-55730 (10⁷ CFU/mL) supplemented with glycerol. Subsequently, the transcription levels of IL-8 and hBD-2 in HaCat cells were analyzed using reverse-transcription polymerase chain reaction (RT-PCR). In addition, cell viability was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. All the obtained data were statistically analyzed using the one-way analysis of variance test, with P < 0.05 set as the level of significance.

Results:

The MTT assays confirmed no cytotoxic effects of glycerol-supplemented L. reuteri on HaCat cells (viability >90%). mRNA expression of IL-8 and hBD-2 increased after exposure to both bacteria. The presence of glycerol-supplemented L. reuteri significantly reduced the expression of IL-8 and hBD-2 on HaCat cells (P < 0.05).

Conclusion:

Glycerol-supplemented L. reuteri reduced the expression of IL-8 and hBD-2, and the results may be proof of principle for a probiotic approach to combating inflammation. However, further studies are needed to validate this probiotic effect.

Defensins in Viral Infection and Pathogenesis

α, β, and θ defensins are effectors of the innate immune system with potent antibacterial, antiviral, and antifungal activity. Defensins have direct antiviral activity in cell culture, with varied mechanisms for individual viruses, although some common themes have emerged. In addition, defensins have potent immunomodulatory activity that can alter innate and adaptive immune responses to viral infection. In some cases, there is evidence for paradoxical escape from defensin neutralization or enhancement of viral infection. The direct and indirect activities of defensins have led to their development as therapeutics and vaccine components. The major area of investigation that continues to lag is the connection between the effects of defensins in cell culture models and viral pathogenesis in vivo. Model systems to study defensin biology, including more physiologic models designed to bridge this gap, are also discussed.

Immunological and epidemiological factors affecting candidiasis in HIV patients beginning antiretroviral therapy in an Asian clinic

OBJECTIVES

Oropharyngeal candidiasis (OPC) is common in HIV patients beginning antiretroviral therapy (ART). Here we address the response to ART, and the roles of poor oral hygiene and defects in local innate immunity with a focus on salivary β-defensins, as they are implicated in control of candidiasis but have not been investigated in this context.

DESIGN

ART naïve HIV-infected adults (n=82) with <200 CD4⁺ T-cells/mm³ attending clinics at Cipto Mangunkusumo Hospital, Jakarta, were examined at the commencement of ART, and 73 were re-examined after 3 months. OPC was detected by clinical examination, and Candida albicans and fungal burdens were determined following culture on CHROMagar and saboroud-dextrose agar (resp). Salivary β-defensins (-2 and -3) were quantified by ELISA. Healthy control subjects (n=40) matched the patients by age and gender.

RESULTS

OPC was evident in 47 patients before ART, and associated with greater fingal burdens. No OPC was detected in healthy controls and culture positivity was rare. ART decreased the prevalence of OPC to 8/73 HIV patients re-examined after 3 months, with reduced total fungal and C. albicans burdens. The incidence of OPC was independent of oral hygiene. Hyposalivation was more common in untreated HIV patients (16%) than after 3 months on ART and was rare in healthy controls. HIV patients were also more likely to have acidic saliva. Salivary β-defensin-2 was elevated in the presence of C. albicans pseudohyphae and OPC after 3 months on ART, but β-defensin-3 was not affected by OPC or ART.

CONCLUSIONS

ART reduces the prevalence of OPC, and the total fungal and C. albicans burden. Levels of salivary β-defensin-2 may associate with OPC in HIV patients responding to ART.

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.

Potential applications of antimicrobial peptides and their mimics in combating caries and pulpal infections

Antimicrobial peptides (AMPs) are short cationic host-defense molecules that provide the early stage of protection against invading microbes. They also have important modulatory roles and act as a bridge between innate and acquired immunity. The types and functions of oral AMPs were reviewed and experimental reports on the use of natural AMPs and their synthetic mimics in caries and pulpal infections were discussed. Natural AMPs in the oral cavity, predominantly defensins, cathelicidins and histatins, possess antimicrobial activities against oral pathogens and biofilms. Incomplete debridement of microorganisms in root canal space may precipitate an exacerbated immune response that results in periradicular bone resorption. Because of their immunomodulatory and wound healing potentials, AMPs stimulate pro-inflammatory cytokine production, recruit host defense cells and regulate immuno-inflammatory responses in the vicinity of the pulp and periapex. Recent rapid advances in the development of synthetic AMP mimics offer exciting opportunities for new therapeutic initiatives in root canal treatment and regenerative endodontics.

STATEMENT OF SIGNIFICANCE

Identification of new therapeutic strategies to combat antibiotic-resistant pathogens and biofilm-associated infections continues to be one of the major challenges in modern medicine. Despite the presence of commercialization hurdles and scientific challenges, interests in using antimicrobial peptides as therapeutic alternatives and adjuvants to combat pathogenic biofilms have never been foreshortened. Not only do these cationic peptides possess rapid killing ability, their multi-modal mechanisms of action render them advantageous in targeting different biofilm sub-populations. These factors, together with adjunctive bioactive functions such as immunomodulation and wound healing enhancement, render AMPs or their synthetic mimics exciting candidates to be considered as adjuncts in the treatment of caries, infected pulps and root canals.

Associations of Toll-Like Receptor and β-Defensin Polymorphisms with Measures of Periodontal Disease (PD) in HIV+ North American Adults: An Exploratory Study

Polymorphisms in toll-like receptor (TLR) and β-defensin (DEFB) genes have been recognized as potential genetic factors that can influence susceptibility to and severity of periodontal diseases (PD). However, data regarding associations between these polymorphisms and PD are still scarce in North American populations, and are not available in HIV+ North American populations. In this exploratory study, we analyzed samples from HIV+ adults (n = 115), who received primary HIV care at 3 local outpatient HIV clinics and were monitored for PD status. We genotyped a total of 41 single nucleotide polymorphisms (SNPs) in 8 TLR genes and copy number variation (CNV) in DEFB4/103A. We performed regression analyses for levels of 3 periodontopathogens in subgingival dental plaques (Porphyromonas gingivalis [Pg], Treponema denticola [Td], and Tannerella forsythia [Tf]) and 3 clinical measures of PD (periodontal probing depth [PPD], gingival recession [REC], and bleeding on probing [BOP]). In all subjects combined, 2 SNPs in TLR1 were significantly associated with Td, and one SNP in TLR2 was significantly associated with BOP. One of the 2 SNPs in TLR1 was significantly associated with Td in Caucasians. In addition, another SNP in TLR1 and a SNP in TLR6 were also significantly associated with Td and Pg, respectively, in Caucasians. All 3 periodontopathogen levels were significantly associated with PPD and BOP, but none was associated with REC. Instrumental variable analysis showed that 8 SNPs in 6 TLR genes were significantly associated with the 3 periodontopathogen levels. However, associations between the 3 periodontopathogen levels and PPD or BOP were not driven by associations with these identified SNPs. No association was found between DEFB4/103A CNV and any periodontopathogen level or clinical measure in all samples, Caucasians, or African Americans. Our exploratory study suggests a role of TLR polymorphisms, particularly TLR1 and TLR6 polymorphisms, in PD in HIV+ North Americans.

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.

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.

Regulation of tracheal antimicrobial peptide gene expression in airway epithelial cells of cattle

β-defensins are an important element of the mucosal innate immune response against bacterial pathogens. Tracheal antimicrobial peptide (TAP) has microbicidal activity against the bacteria that cause bovine respiratory disease, and its expression in tracheal epithelial cells is upregulated by bacterial products including lipopolysaccharide (LPS, a TLR4 agonist), Pam3CSK4 (an agonist of Toll-like receptor 2/1), and interleukin (IL)-17A. The objectives of this study were to identify the signalling pathway by which LPS, Pam3CSK4 and IL-17A induce TAP gene expression, and to determine the effect of glucocorticoid as a model of stress on this epithelial innate immune response. In primary cultures of bovine tracheal epithelial cells (bTEC), LPS, Pam3CSK4 and IL-17A each stimulated TAP gene expression. This effect was abrogated by caffeic acid phenylester (CAPE), an inhibitor of NF-κB. Similarly, western analysis showed that LPS, Pam3CSK4 and IL-17A each induced translocation of NF-κB p65 from the cytoplasm to the nucleus, but pre-treatment with CAPE inhibited this response. Finally, pre-treatment of bTEC with the glucocorticoid dexamethasone abolished the stimulatory effect of LPS, Pam3CSK4 and IL-17A on upregulation of TAP gene expression. These findings indicate that NF-κB activation is necessary for induction of TAP gene expression by LPS (a TLR4 agonist), Pam3CSK4 (a TLR2/1 agonist), or IL-17A. Furthermore, this stimulatory response is inhibited by glucocorticoid, suggesting this as one mechanism by which stress increases the risk of bacterial pneumonia. These findings have implications for understanding the pathogenesis of stress-associated bacterial pneumonia, and for developing methods to stimulate innate immune responses in the respiratory tract of cattle.

Triclosan alters antimicrobial and inflammatory responses of epithelial cells

Periodontal diseases are a class of pathologies wherein oral microbes induce harmful immune responses in a susceptible host. Therefore, an agent that can both reduce microbial burden and lessen pathogenesis of localized inflammation would have beneficial effects in periodontal disease; 2,4,4-trichloro-2-hydroxydiphenyl-ether [triclosan] is currently used in oral care products owing to broad spectrum antimicrobial and anti-inflammatory properties.

OBJECTIVE

To determine effects of triclosan on the response of oral epithelial cells to stimulation with the inflammatory microbial product lipopolysaccharide (LPS), a ligand for toll-like receptor 4 [TLR4].

MATERIALS/METHODS

Primary human oral epithelial cells were stimulated with LPS in the presence and/or absence of triclosan after which expression of pro-inflammatory cytokines, β-defensins, micro-RNAs [miRNAs], or TLR-signaling pathway proteins were evaluated.

RESULTS

Here, we demonstrate that triclosan is a potent inhibitor of oral epithelial cell LPS-induced pro-inflammatory responses by inducing miRNA regulation of the TLR-signaling pathway. Triclosan was not a pan-suppresser of oral epithelial cell responses as β-defensin 2 [βD2] and βD3 were upregulated by triclosan following LPS-stimulation.

CONCLUSIONS

These data demonstrate both a novel antimicrobial mechanism by which triclosan improves plaque control and an additional anti-inflammatory property, which could have beneficial effects in periodontal disease resolution.

Tissue- and age-dependent expression of the bovine DEFB103 gene and protein

Beta-defensin 103 (DEFB103) shares little homology with 8 other members of the bovine beta-defensin family and in other species DEFB103 protein has diverse functions, including antimicrobial activity, a chemoattractant for dendritic cells, enhancing epithelial wound repair and regulating hair colour. Expression of the bovine DEFB103 gene was surveyed in 27 tissues and transcript was most abundant in tissues with stratified squamous epithelium. Oral cavity epithelial tissues and nictitating membrane consistently expressed high levels of DEFB103 gene transcript. An age-dependent decrease (P < 0.05) in DEFB103 gene expression was only observed for buccal epithelium when comparing healthy 10- to 14-day-old and 10- to 12-month-old calves. A bovine herpesvirus-1 respiratory infection did, however, significantly (P < 0.05) up-regulate DEFB103 gene expression in the buccal epithelium of 6- to 8-month-old calves. Finally, DEFB103 transcript was low in lymph nodes draining the skin and at the limit of detection in other internal organs such as lung, intestine and kidney. Affinity-purified rabbit antisera to bovine DEFB103 was used to identify cells expressing DEFB103 protein within tissues with stratified squamous epitheliums. DEFB103 protein was most abundant in basal epithelial cells and was present in these cells prior to birth. Beta-defensins have been identified as regulators of dendritic cell (DC) chemokine responses and we observed a close association between DCs and epithelial cells expressing DEFB103 in both the fetus and newborn calf. In conclusion, bovine DEFB103 gene expression is most abundant in stratified squamous epithelium with DEFB103 protein localised to basal epithelial cells. These observations are consistent with proposed roles for DEFB103 in DC recruitment and repair of stratified squamous epithelium.

Chronic tonsillitis is not associated with beta defensin 1 gene polymorphisms in Turkish population

BACKGROUND

Defensins are antimicrobial peptides expressed on mucosal surfaces. They function as part of the innate immune system. Palatine tonsils play important roles in innate immune system. However, our knowledge on the pathophysiology of chronic tonsils is limited.

OBJECTIVE

The aim of this study was to investigate the association between beta defensin 1 gene single nucleotide polymorphisms and chronic tonsillitis.

STUDY DESIGN

Prospective, non-randomized, controlled clinical study.

SETTING

Tertiary referral center.

SUBJECTS AND METHODS

Eighty six patients with chronic tonsillitis and eighty controls without history of chronic tonsillitis were enrolled in this study. Genotypes were determined by restriction fragment length polymorphism analyses after polymerase chain reaction.

RESULTS

Genotype and allele frequencies of the -20G/A (rs11362), -44C/G (rs1800972) and -52G/A (rs1799946) single nucleotide polymorphisms were not statistically different between patients and control groups (p>0.05).

CONCLUSION

In this study, we found that DEFB1 gene -20G/A, -44C/G and -52G/A single nucleotide polymorphisms were not associated with chronic tonsillitis. Studies, which analyse other polymorphism of the beta defensin 1 gene in large case series, should be conducted to understand the role of DEFB1 gene on chronic tonsillitis.

Effects of whole cigarette smoke on human beta defensins expression and secretion by oral mucosal epithelial cells

Background

Cigarette smoke a recognized risk factor for many systemic diseases and also oral diseases. Human beta defensins (HBDs), a group of important antimicrobial peptides expressed by the epithelium, are crucial for local defense and tissue homeostasis of oral cavity. The aim of this study was to evaluate potential effects of whole cigarette smoke (WCS) exposure on the expression and secretion of HBDs by oral mucosal epithelial cells.

Methods

Immortalized human oral mucosal epithelial (Leuk-1) cells were exposed to WCS for various time periods. HBD-1, -2 and -3 expression and subcellular localization were detected by real time qPCR, immunofluorescence assay and confocal microscopy. According to the relative fluorescent intensity, the expression levels of HBD-1, -2 and -3 were evaluated by digital image analysis system. The alteration of HBD-1, -2 and -3 secretion levels was measured by the Enzyme-Linked Immunosorbent Assay.

Results

WCS exposure remarkably attenuated HBD-1 expression and secretion while clearly enhanced HBD-2, -3 expression levels and HBD-2 secretion by Leuk-l cells. It appeared that there was no significant effect of WCS exposure on HBD-3 secretion.

Conclusions

WCS exposure could modulate expression and secretion of HBDs by oral mucosal epithelial cells, establishing a link between cigarette smoke and abnormal levels of antimicrobial peptides. The present results may give a new perspective to investigate smoking-related local defense suppression and oral disease occurrence.

HBD-2 is downregulated in oral carcinoma cells by DNA hypermethylation, and increased expression of hBD-2 by DNA demethylation and gene transfection inhibits cell proliferation and invasion

Human β-defensin-2 (hBD-2) is a type of epithelial antimicrobial peptide. The expression level of hBD-2 mRNA is lower in oral carcinoma cells (OCCs) than in healthy oral epithelium. Yet, it is still unknown how hBD-2 expression is downregulated in OCCs. The present study investigated DNA hypermethylation of hBD-2 in OCCs and the effect of the demethylation and increased expression of hBD-2 on cell proliferation and invasion. Six different types of oral carcinoma cell lines (OSC-19, BSC-OF, SAS, HSC-2, HSC-4 and HSY) and normal oral keratinocytes (NOKs) were used. The expression levels of hBD-2 in all OCCs were significantly lower than that in the NOKs. Treatment with DNA methyltransferase inhibitor, 5-aza-dC, at the concentration of 50 µM significantly induced upregulation of expression of hBD-2 in the OCCs. Using methylation-specific PCR, DNA hypermethylation was observed in all OCCs. These results suggest that DNA hypermethylation is, at least in part, involved in the decreased expression of hBD-2 in OCCs. We examined the effect of 5-aza-dC on the cell proliferation and invasive ability of OCCs. The cell invasion assays showed that the number of OCCs treated with 5-aza-dC on the filters was significantly lower than that of the controls. We examined whether increased expression of hBD-2 generated by gene transfection inhibited the proliferation and invasion of SAS cells. The number of SAS cells exhibiting increased expression of hBD-2 on the filters in the invasion assay were significantly lower on day 7 when compared with the control. hBD-2 may function as a tumor suppressor. Increased expression of hBD-2 induced by demethylation or increased expression generated by gene transfection may be useful therapeutic methods for oral carcinoma.

Effects of stress on mouse β-defensin-3 expression in the upper digestive mucosa

PURPOSE

Gastrointestinal integrity and immune surveillance are affected by stress. Stress also adversely affects mucosal barrier function. β-defensins constitute an integral component of the innate immune system as antimicrobial peptides, serving as the first line of defense against microbial pathogens at the epithelial surfaces of the upper digestive mucosa. The primary objective of this study was to determine the effects of stress on the expression profile of mouse β-defensin-3 in the upper digestive mucosa of mice with diabetes.

MATERIALS AND METHODS

We established a mouse model of restraint stress by using NSY/Hos mice with type 2 diabetes mellitus. We used real-time polymerase chain reaction, in situ hybridization, and immunohistochemistry to investigate the effects of stress and glucocorticoid administration on mouse β-defensin-3 expression in the upper digestive mucosa of the gingiva, esophagus, and stomach.

RESULTS

Mouse β-defensin-3 mRNA expression was higher in the esophagus than in the gingiva or stomach (p<0.05). In the esophagus, mouse β-defensin-3 mRNA expression was lower in stressed mice than in non-stressed mice (p<0.05). Furthermore, immunoreactivity to mouse β-defensin-3 protein was lower in the esophagus of stressed mice than non-stressed mice, consistent with the results of mRNA expression analysis. Systemic glucocorticoid administration also downregulated esophageal mouse β-defensin-3 mRNA expression.

CONCLUSION

Our novel findings show that stress decreases mouse β-defensin-3 expression in the esophagus of mice with diabetes, possibly due to increased endogenous glucocorticoid production. It appears to be highly likely that stress management may normalize mucosal antimicrobial defenses in patients with diabetes.

Transcription profiling reveals potential mechanisms of dysbiosis in the oral microbiome of rhesus macaques with chronic untreated SIV infection

A majority of individuals infected with human immunodeficiency virus (HIV) have inadequate access to antiretroviral therapy and ultimately develop debilitating oral infections that often correlate with disease progression. Due to the impracticalities of conducting host-microbe systems-based studies in HIV infected patients, we have evaluated the potential of simian immunodeficiency virus (SIV) infected rhesus macaques to serve as a non-human primate model for oral manifestations of HIV disease. We present the first description of the rhesus macaque oral microbiota and show that a mixture of human commensal bacteria and “macaque versions” of human commensals colonize the tongue dorsum and dental plaque. Our findings indicate that SIV infection results in chronic activation of antiviral and inflammatory responses in the tongue mucosa that may collectively lead to repression of epithelial development and impact the microbiome. In addition, we show that dysbiosis of the lingual microbiome in SIV infection is characterized by outgrowth of Gemella morbillorum that may result from impaired macrophage function. Finally, we provide evidence that the increased capacity of opportunistic pathogens (e.g. E. coli) to colonize the microbiome is associated with reduced production of antimicrobial peptides.

Gene polymorphism of β-defensin-1 is associated with susceptibility to periodontitis in Japanese

Periodontitis is a multifactorial disease associated with genetic and environmental factors. Single-nucleotide polymorphisms (SNPs) are associated with susceptibility to common diseases such as diabetes and periodontitis. Although the oral cavity is exposed to various organisms, the conditions are well controlled by innate and acquired immune systems. Antimicrobial peptides (AMPs) play an important role in the innate immune system; however, the association of AMP-SNPs with periodontitis has not been fully elucidated. This study investigated the relationship between AMP-SNPs and periodontitis in Japanese. One hundred and five Japanese subjects were recruited, which included patients with aggressive, severe, moderate and mild periodontitis, and age-matched healthy controls. Genomic DNA was isolated from peripheral blood and genotypes of SNPs of β-defensin-1 and lactoferrin genes (DEFB1: rs1799946, rs1800972 and rs11362; and LTF: rs1126478) were investigated using the PCR-Invader assay. Protein level of AMPs in gingival crevicular fluid (GCF) was quantified by ELISA. Case-control studies revealed that the -44 CC genotype of DEFB1 (rs1800972) was associated with periodontitis (OR 2.51), particularly with severe chronic periodontitis (OR 4.15) and with combined severe and moderate chronic periodontitis (OR 4.04). No statistical differences were found in other genotypes. The β-defensin-1 concentrations in GCF were significantly lower in subjects with the -44 CC genotype of DEFB1 than in those without this genotype. No significant differences between GCF concentrations of AMPs and other genotypes were detected. The -44 CC genotype of the β-defensin-1 gene (DEFB1 rs1800972) may be associated with susceptibility to chronic periodontitis in Japanese.

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.

Beta-defensin-2 Genomic Copy Number Variation and Chronic Periodontitis

Chronic periodontitis (ChP) is a multifactorial disease influenced by microbial and host genetic variability; however, the role of beta-defensin-2 genomic ( DEFB4) copy number (CN) variation (V) in ChP remains unknown. The association of the occurrence and severity of ChP and DEFB4 CNV was analyzed. Our study included 227 unrelated Caucasians, that is, 136 ChP patients (combined ChP) and 91 control individuals. The combined ChP group was subdivided into the severe ChP and slight-to-moderate ChP subgroups. To determine DEFB4 CNV, we isolated genomic DNA samples and analyzed them by relative quantitation using the comparative CT method. The serum beta-defensin-2 (hBD-2) level was determined via ELISA. The distribution pattern and mean DEFB4 CN did not differ significantly in combined ChP cases vs. the controls; however, the mean DEFB4 CN in the severe ChP group differed significantly from those for the control and slight-to-moderate ChP groups. Low DEFB4 CN increased the risk of severe ChP by about 3-fold. DEFB4 CN was inversely associated with average attachment loss. Mean serum hBD-2 levels were highest in the controls, followed by the slight-to-moderate ChP group and the severe ChP group. The results suggested an association between decreased DEFB4 CN and serum hBD-2 levels and periodontitis severity.

Human β-defensin-3 correlates with muscle fibre degeneration in idiopathic inflammatory myopathies

Sporadic inclusion body myositis (sIBM) and polymyositis (PM) are characterized by muscle inflammation, with sIBM showing additional degenerative alterations. In this study we investigated human beta defensins and associated TLRs to elucidate the role of the innate immune system in idiopathic inflammatory myopathies (IIM), and its association with inflammatory and degenerative alterations. Expression levels of human beta-defensin (HBD)-1, HBD-2, HBD-3 and TLR2, 3, 4, 7 and 9 were analysed by quantitative real-time PCR in skeletal muscle tissue. Localization of HBD-3, collagen 6, dystrophin, CD8-positive T-cells, CD-68-positive macrophages, β-amyloid, the autophagy marker LC3, and TLR3 were detected by immunofluorescence and co-localization was quantified. HBD-3 and all TLRs except for TLR9 were overexpressed in both IIM with significant overexpression of TLR3 in sIBM. HBD-3 showed characteristic intracellular accumulations near deposits of β-amyloid, LC3 and TLR3 in sIBM, and was detected in inflammatory infiltrations and macrophages invading necrotic muscle fibres in both IIM. The characteristic intracellular localization of HBD-3 near markers of degeneration and autophagy, and overexpression of endosomal TLR3 in sIBM hint at different pathogenetic mechanisms in sIBM compared with PM. This descriptive study serves as a first approach to the role of the innate immune system in sIBM and PM.

Toluene Exposure Leads to a Change in Expression Patterns of β Defensins in the Mouse Tracheal Epithelium

Defensins are generally implicated in the quick resistance of epithelial surfaces to microbials; however, recent reports have indicated that defensins also have unknown purposes in relation to noninfectious diseases. In this study, the localization patterns of anti-microbial peptides, β defensins (BDs), in the tracheal epithelium of male C3H mice under exposure to toluene were analyzed by immunohistochemistry. Mice were exposed one to ten times to toluene for 30 min by nose-only inhalation. Expression of BDs was revealed by immunohistochemistry in serial sections of trachea after the final exposure. Expression of BD-1 was usually observed at almost the same levels in all exposure groups, and expression of BD-2 was observed in the control group; however, the signals for BD-2 decreased gradually with frequency of exposure. In the group exposed ten times, expression of BD-2 decreased to far lower than that of the control group. No expression of BD-3 was detected in any groups. Interestingly, expression of BD-4 increased to the maximum in the group exposed four times and decreased to a level lower than that of the control in the group exposed ten times. The results of the present study indicated that toluene gas might change the expression pattern of BDs in the tracheal epithelial cells. The oscillation of expression of BD-4 was quite characteristic and might contribute to morphological damage in on the epithelial cells.

Association studies of the copy-number variable ß-defensin cluster on 8p23.1 in adenocarcinoma and chronic pancreatitis

Background

Human ß-defensins are a family of antimicrobial peptides located at the mucosal surface. Both sequence multi-site variations (MSV) and copy-number variants (CNV) of the defensin-encoding genes are associated with increased risk for various diseases, including cancer and inflammatory conditions such as psoriasis and acute pancreatitis. In a case–control study, we investigated the association between MSV in DEFB104 as well as defensin gene (DEF) cluster copy number (CN), and pancreatic ductal adenocarcinoma (PDAC) and chronic pancreatitis (CP).

Results

Two groups of PDAC (N=70) and CP (N=60) patients were compared to matched healthy control groups CARLA1 (N=232) and CARLA2 (N=160), respectively. Four DEFB104 MSV were haplotyped by PCR, cloning and sequencing. DEF cluster CN was determined by multiplex ligation-dependent probe amplification.

Neither the PDAC nor the CP cohorts show significant differences in the DEFB104 haplotype distribution compared to the respective control groups CARLA1 and CARLA2, respectively.

The diploid DEF cluster CN exhibit a significantly different distribution between PDAC and CARLA1 (Fisher’s exact test P=0.027), but not between CP and CARLA2 (P=0.867).

Conclusion

Different DEF cluster b CN distribution between PDAC patients and healthy controls indicate a potential protective effect of higher CNs against the disease.

Expression of oral secretory leukocyte protease inhibitor in HIV-infected subjects with long-term use of antiretroviral therapy

BACKGROUND

The objectives of this study were to determine (i) the expression of oral secretory leukocyte protease inhibitor (SLPI) in HIV-infected subjects compared with non-HIV controls, (ii) the oral SLPI expression in HIV-infected subjects with antiretroviral therapy (ART) compared with those without ART, and (iii) factors associated with the expression of oral SLPI.

METHODS

Oral tissues and samples of both un-stimulated and stimulated saliva were collected from HIV-infected subjects with and without ART, and non-HIV individuals. The expression of SLPI mRNA in the tissue was determined by quantitative real-time PCR. Salivary SLPI protein was detected using ELISA. Chi-square test and logistic regression analysis were performed to determine the association between HIV/ART status and the expression of oral SLPI.

RESULTS

One hundred and fifty-seven HIV-infected subjects were enrolled: 99 on ART (age range, 23-57 years; mean, 39 years), 58 not on ART (age range, 20-59 years; mean, 34 years), and 50 non-HIV controls (age range, 19-59 years; mean, 36 years). The most common ART regimen was 2NRTIs + 1NNRTI. The expression of oral SLPI in stimulated saliva was significantly decreased with HIV infection (P < 0.001). The expression was also significantly different with respect to ART use (P = 0.007). Smoking, CD4(+) cell count, and HIV viral load were the factors associated with the oral SLPI expression.

CONCLUSION

The expression of oral SLPI is altered by HIV infection and use of ART. Thus, oral SLPI may be the useful biomarker to identify subjects at risk of infections and malignant transformation due to HIV infection and long-term ART.

Effect of human beta-defensin-3 on head and neck cancer cell migration using micro-fabricated cell islands

BACKGROUND

To examine the effect of the natural antimicrobial peptide human β-defensin-3 (hBD-3), on the migration of a head and neck cancer cell line in vitro using microfabrication and soft-lithographic techniques.

METHODS

TR146 cancer cells were seeded in Petri dishes with microfabricated wells for cell migration assays. Total 54 cell islands were used of various shape and size and experimental media type. Cell migration assays were analyzed in six group media: Dulbecco's modified medium (DMEM); DMEM with vascular endothelial growth factor (VEGF); Conditioned media of human embryonic kidney cells (HEK 239) expressing hBD-3 via transfected cloned pcDNA3 as CM/hBD-3; CM/hBD-3+ VEGF; conditioned medium from non-transfected HEK 239 (not expressing hBD-3) as control (CM); and the last group was CM + VEGF. Cell islands were circular or square and varied in size (0.25 mm(2), 0.125 mm(2), and 0.0625 mm(2)). Cell islands were imaged at t=0 h, 3 h, 6 h, and 24 h.

RESULTS

The results show cancer cell islands that originally were smaller had higher migration indices. There was no difference of MIs between circular and square cell islands. MIs at the end point were significantly different among the groups except between CM and CM-hBD-3+ VEGF.

CONCLUSIONS

VEGF enhanced cancer cell migration. The combination of DMEM and VEGF showed a synergistic effect on this phenomenon of cancer cell migration. Conditioned medium with hBD-3 suppressed cancer cell migration. hBD-3 suppressed VEGF enhancement of TR146 cancer cell migration.

Oral human β-defensin 2 in HIV-infected subjects with long-term use of antiretroviral therapy

BACKGROUND

The objectives of this study were to determine (i) oral hBD2 expression in HIV-infected subjects compared with non-HIV controls, (ii) the expression of oral hBD2 in HIV-infected subjects with antiretroviral therapy (ART) compared with those without ART, and (iii) factors associated with the expression of oral hBD2.

METHODS

Oral examination and punched biopsy on buccal mucosa were performed in HIV-infected subjects with and without ART, and non-HIV individuals. The expression of hBD2 mRNA was determined by quantitative real-time PCR. Saliva samples of both un-stimulated and stimulated saliva were collected and analyzed for hBD2 levels using ELISA. Student's t-test and nonparametric multi-way ANOVA test were used for comparison of measurements between or among groups.

RESULTS

One hundred and fifty-seven HIV-infected subjects were enrolled: 99 on ART (age range, 23-57 years; mean 39 years), 58 not on ART (age range, 20-59 years; mean 34 years), and 50 non-HIV controls (age range, 19-59 years; mean 36 years). The most common ART regimen was two nucleoside reverse transcriptase inhibitors + one non-nucleoside reverse transcriptase inhibitor. Salivary levels of hBD2 were significantly increased in HIV infection (P < 0.001). The levels of hBD2 in stimulated saliva were also found to be significantly different between HIV-infected subjects who were and were not on ART (P < 0.001). No significant difference was observed with the expression of hBD2 mRNA.

CONCLUSION

Oral innate immunity is affected by HIV infection and use of ART. Salivary hBD2 levels may be the useful biomarkers to monitor those on long-term ART who are at risk of developing oral infections and malignant transformation.

Innate immunity and the role of defensins in otitis media

Otitis media is the most common pediatric disease in developed countries and a significant cause of morbidity and hearing loss in developing countries. The innate immune system is essential to protecting the middle ear from infection. Defensins, broad-spectrum cationic antimicrobial peptides, have been implicated in prevention of and the early response to acute otitis media; however, the mechanisms by which defensins and other antimicrobial molecules mediate this protection have not been completely elucidated. In both animal otitis media models and human middle ear epithelial cell culture models, β-defensins are highly induced and effectively kill the common pathogens associated with otitis media. We review the importance of innate immunity in protecting the middle ear and recent advances in understanding the roles of defensins and other antimicrobial molecules in the prevention and treatment of otitis media. The extremely high prevalence of otitis media, in spite of sophisticated innate and adaptive immune systems, is a vexing problem for clinicians and scientists. We therefore also review mechanisms by which bacteria evade innate immune defenses.

Will new generations of modified antimicrobial peptides improve their potential as pharmaceuticals?

The concept of antimicrobial peptides (AMPs) as potent pharmaceuticals is firmly established in the literature, and most research articles on this topic conclude by stating that AMPs represent promising therapeutic agents against bacterial and fungal pathogens. Indeed, early research in this field showed that AMPs were diverse in nature, had high activities with low minimal inhibitory concentrations, had broad spectrums of activity against bacterial, fungal and viral pathogens, and could easily be manipulated to alter their specificities, reduce their cytotoxicities and increase their antimicrobial activities. Unfortunately, commercial development of these peptides, for even the simplest of applications, has been very limited. With some peptides there are obstacles with their manufacture, in vivo efficacy and in vivo retention. More recently, the focus has shifted. Contemporary research now uses a more sophisticated approach to develop AMPs that surmount many of these prior obstacles. AMP mimetics, hybrid AMPs, AMP congeners, cyclotides and stabilised AMPs, AMP conjugates and immobilised AMPs have all emerged with selective or 'targeted' antimicrobial activities, improved retention, or unique abilities that allow them to bind to medical or industrial surfaces. These groups of new peptides have creative medical and industrial application potentials to treat antibiotic-resistant bacterial infections and septic shock, to preserve food or to sanitise surfaces both in vitro and in vivo.