Reduced human beta defensin 3 in individuals with periodontal disease

Prokaryotic Expression and Functional Verification of Antimicrobial Peptide LRGG

The antimicrobial peptide LRGG (LLRLLRRGGRRLLRLL-NH2) was designed and chemically synthesized in a study conducted by Jia et al. Gram-negative bacteria were found to be sensitive to LRGG and exhibited a high therapeutic index. Genetic engineering methods were used to create the prokaryotic fusion expression vector pQE-GFP-LRGG, and the resulting corresponding fusion protein GFP-LRGG was subsequently expressed and purified. The precursor GFP was then removed by TEV proteolysis, and pure LRGG was obtained after another round of purification and endotoxin removal. The prokaryotic-expressed antimicrobial peptide LRGG displays a broad-spectrum antibacterial effect on Gram-negative bacteria, and its minimum inhibitory activity (MIC) against Escherichia coli can reach 2 μg/mL. Compared to the chemically synthesized LRGG, the prokaryotic-expressed LRGG exhibits similar temperature, pH, salt ion, serum stability, and cell selectivity. Furthermore, prokaryotic-expressed LRGG showed excellent therapeutic effects in both the infection model of cell selectivity and no embryotoxicity in a Galleria mellonella infection model. The mechanism by which LRGG causes bacterial death was found to be the disruption of the Gram-negative cell membrane.

Effects of Bdellovibrio bacteriovorus HD100 on experimental periodontitis in rats

AIM

The aim of this study was to evaluate the effects of Bdellovibrio bacteriovorus HD100 on experimental periodontitis (EP) in rats.

METHODS

Thirty-two rats were divided into four groups: control, C-HD100 (B. bacteriovorus), EP, and EP-HD100. On day 0, EP was induced by the placement of cotton ligatures around the mandibular first molars (MFMs) in the EP and EP-HD100 groups. In the C-HD100 and EP-HD100 groups, suspensions containing 1 × 10⁹  PUF/ml of B. bacteriovorus HD100 were topically administered to the subgingival region of MFMs on days 0, 3, and 7. Animals were euthanized on day 14. Morphometrics analyses were performed in hemimandibles. The levels of tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1, IL-10, IL-1β, transforming growth factor beta (TGF-β), macrophage colony-stimulating factor (M-CSF) and regulated on activation and normal T cell expressed and secreted (RANTES) were determined by enzymatic immunoassays in gingival tissues. Beta defensin (BD)-1, BD-2, and BD-3, Toll-like receptors (TLR)-2 and TLR-4, and a cluster of differentiation (CD)-4, CD-8 and CD-57 were analyzed by immunohistochemistry in hemimandibles. Data were statistically analyzed.

RESULTS

The EP group showed greater alveolar bone loss than EP-HD100 (p < .05). The EP-HD100 group showed higher levels of MCP-1, RANTES, IL-10, and TGF-β, lower levels of TNF-α than the EP group (p < .05). No differences were observed in IL-1β, IL-6, and M-CSF levels between EP and EP-HD100 groups. The C-HD100 group had higher IL-6, TNF-α, RANTES, and MCP-1 levels than the control group (p < .05). Regarding BD, the EP-HD100 group showed a larger immunolabeling pattern for BD-1, BD-2, and BD-3 than the EP group (p < .05). No significant differences in the immunolabeling pattern were observed for TLR-2, TLR-4, CD-4, CD-8, and CD-57 between EP and EP-HD100 groups.

CONCLUSION

The topical use of B. bacteriovorus HD100 reduces alveolar bone loss, increases expression of BD, and modulates the cytokines levels on periodontal tissues in rats with EP.

Probiotic consumption can modify the resilience of periodontal tissues in rats under experimental periodontitis

BACKGROUND

This study evaluated the effects of systemic administration of Bifidobacterium animalis subsp. lactis HN019 (B. lactis HN019) on experimental periodontitis (EP) in rats.

METHODS

Thirty-two rats were allocated to groups C (control), C-HN019 (probiotic), EP (EP only), and EP-HN019 (EP+probiotic). From day 0, the animals of C-HN019 and EP-HN019 groups received B. lactis HN019 (1 × 10⁹ CFU/ml) daily. On the 14th day, the animals of EP and EP-HN019 groups received silk ligature around mandibular molars. Animals were euthanized on the 28th day. Samples of oral biofilm, gingival tissues, blood serum, and mandible were obtained for microtomographic, histomorphometric, microbiological, and immunological analyses. Data were statistically analyzed (p < 0.05).

RESULTS

Group EP-HN019 presented significantly less alveolar bone loss when compared with Group EP in histomorphometric and microtomographic analyses. In gingival tissue and serum, Group EP-HN019 presented lower proinflammatory/anti-inflammatory cytokines ratios than Group EP. Group EP-HN019 showed higher expression of beta-defensins and less TRAP-positive cells than Group EP. Group EP presented higher gene expression of Ifng and lower gene expression of Foxp3 when compared with Group EP-HN019 in gingival tissue. In oral biofilm, EP-HN019 group presented a lower percentage of species similar to Fusobacterium periodonticum and a higher percentage of species similar to Actinomyces gereneseriae, Actinomyces israelli, and Streptococcus gordonii when compared with Group EP. There was a significant increase of B. lactis HN019 after administration of probiotic therapy in oral biofilm of Group EP-HN019.

CONCLUSION

The consumption of B. lactis HN019 promotes a protective effect against alveolar bone loss by modifying local and systemic microbiological and immunoinflammatory parameters.

Antimicrobial Proteins: Structure, Molecular Action, and Therapeutic Potential

Second- and third-line treatments of patients with antibiotic-resistant infections can have serious side effects, such as organ failure with prolonged care and recovery. As clinical practices such as cancer therapies, chronic disease treatment, and organ transplantation rely on the ability of available antibiotics to fight infection, the increased resistance of microbial pathogens presents a multifaceted, serious public health concern worldwide. The pipeline of traditional antibiotics is exhausted and unable to overcome the continuously developing multi-drug resistance. To that end, the widely observed limitation of clinically utilized antibiotics has prompted researchers to find a clinically relevant alternate antimicrobial strategy. In recent decades, the discovery of antimicrobial peptides (AMPs) as an excellent candidate to overcome antibiotic resistance has received further attention, particularly from scientists, health professionals, and the pharmaceutical industry. Effective AMPs are characterized by a broad spectrum of antimicrobial activities, high pathogen specificity, and low toxicity. In addition to their antimicrobial activity, AMPs have been found to be involved in a variety of biological functions, including immune regulation, angiogenesis, wound healing, and antitumor activity. This review provides a current overview of the structure, molecular action, and therapeutic potential of AMPs.

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.

Impact of smoking on protein levels of beta-defensins in periodontal disease

Antimicrobial peptides (AMPs) are important components of the host response against invading pathogens. In addition to their direct antimicrobial activity, they can also participate in the immune system modulation. However, the role of AMPs in the etiopathogenesis of periodontal disease and the risk factors that may influence their expression in the oral cavity are not fully understood. The aim of this study was to determine the impact of smoking on beta-defensin (hBD) 1 and 2 levels analyzing samples from periodontitis patients. Fifty patients with periodontitis, 25 smokers and 25 non-smokers, and 20 periodontally healthy patients were recruited. After periodontal clinical evaluation, gingival crevicular fluid (GCF) samples were collected from healthy sites of patients without periodontal disease and from healthy and diseased sites of patients with periodontitis. Peptides quantification was performed by sandwich ELISA technique. Smokers showed reduced GCF hBD 1 levels and increased hBD 2 levels compared to non-smokers in diseased sites (p <0.05). Higher levels of hBD 1 were observed in healthy sites of patients without periodontal disease than in healthy sites of patients with periodontitis (p<0.0001). Diseased sites of non-smokers presented higher levels of hBD 2 than healthy sites (p <0.05). These results reveal that protein levels of hBDs 1 and 2 can be impaired by cigarette smoking in the presence of periodontal disease.

Cationic Antimicrobial Peptides Are Leading the Way to Combat Oropathogenic Infections

Oral dental infections are one of the most common diseases affecting humans, with caries and periodontal disease having the highest incidence. Caries and periodontal disease arise from infections caused by oral bacterial pathogens. Current misuse and overuse of antibiotic treatments have led to the development of antimicrobial resistance. However, recent studies have shown that cationic antimicrobial peptides are a promising family of antibacterial agents that are active against oral pathogenic bacteria and also possess less propensity for development of antimicrobial resistance. This timely Review has a focus on two primary subjects: (i) the oral bacterial pathogens associated with dental infections and (ii) the current development of antimicrobial peptides targeting oral pathogens.

Dysregulation of human beta-defensin-3 expression in the peripheral blood of patients with sepsis

Objectives:

Sepsis is a serious medical condition caused by the body’s systemic inflammatory response to infections. The antimicrobial peptides, human beta-defensins, play a key role in modulating host immune responses, and aberrant expression of human beta-defensins has been implicated in many infections and inflammatory diseases. However, little is known about the expression of human beta-defensin-3 in systemic infectious diseases.

Methods:

We investigated the gene expression and protein level of human beta-defensin-3 in peripheral whole blood from 107 participants—67 patients with sepsis and 40 healthy controls—and evaluated the feasibility of human beta-defensin-3 as an indicator for sepsis. Total RNA was extracted from peripheral blood samples, and relative mRNA expression of human beta-defensin-3 was determined by reverse transcription-quantitative polymerase chain reaction. Plasma concentration of human beta-defensin-3 was measured by enzyme-linked immunosorbent assay. Pearson’s correlation analysis was performed to assess the relationship between human beta-defensin-3 mRNA and protein levels. Receiver operating characteristic analysis was performed to evaluate the value of human beta-defensin-3 as a biomarker for sepsis.

Results:

Human beta-defensin-3 mRNA expression was significantly downregulated in sepsis patients compared to controls (p = 0.001). The mean fold change of mRNA expression (±standard error) was 0.82 ± 0.63 in sepsis patients and 1.39 ± 1.09 in controls. Plasma concentration of human beta-defensin-3 (pg/mL) was significantly lower in sepsis patients compared to healthy controls (p = 0.039). The mean protein concentration (±standard error) was 539.6 ± 39.4 in sepsis patients and 715.5 ± 53 in controls. There was a significant correlation between human beta-defensin-3 mRNA expression and the corresponding protein level in sepsis patients (r = 0.358, p = 0.04), but not in healthy controls (r = 0.124, p = 0.51). For discriminating sepsis patients from healthy controls, the area under the receiver operating characteristic curve was 0.722 (95% confidence interval: 0.597–0.847, p = 0.002) for human beta-defensin-3 mRNA and 0.689 (95% confidence interval: 0.557–0.827, p = 0.009) for human beta-defensin-3 protein.

Conclusion:

This is the first study to show the downregulation of human beta-defensin-3 gene expression and protein level in sepsis, which may contribute to the complex immunological imbalance in sepsis. The significant correlation between human beta-defensin-3 mRNA expression and protein concentration suggests that mRNA expression could be used to predict protein level. Our study also showed a potential role of human beta-defensin-3 as a blood-based biomarker for sepsis. More studies on the clinical significance of human beta-defensin-3 in sepsis could further support a biomarker development.

Significance of the chemokine CXCL10 and human beta-defensin-3 as biomarkers of pulmonary tuberculosis

The biomarker significance of IL-35, chemokines (CXCL9 and CXCL10) and human beta-defensins (hBD2 and hBD3) was determined in pulmonary tuberculosis (TB) of 105 Iraqi patients; 37 had active disease, 41 had multi-drug resistant (MDR) PTB and 27 had a relapse of TB. A control sample of 79 healthy persons was also included. Serum levels of markers were assessed using enzyme-linked immunosorbent assay kits. Kruskal-Wallis test together with Dunn-Bonferroni post hoc test revealed significance differences between patients and controls in levels of IL-35, CXCL9, CXCL10 and hBD3, while hBD2 showed no significant difference. Receiver operating characteristic analysis demonstrated that CXCL10 and hBD3 were the most significant markers in predicting TB, particularly active disease. Logistic regression analysis proposed the susceptibility role of CXCL10 in TB. Gender- and age-dependent variations were also observed. Spearman's rank correlation analysis showed different correlations between markers in each group of patients and controls. In conclusion, CXCL10 was up-regulated in serum of TB patients, while hBD3 showed down-regulated level. Both serum proteins are possible candidate biomarkers for evaluation of TB progression, particularly in active disease.

Immunoinformatics analysis to design novel epitope based vaccine candidate targeting the glycoprotein and nucleoprotein of Lassa mammarenavirus (LASMV) using strains from Nigeria

Lassa mammarenavirus (LASMV) is responsible for a specific type of acute viral hemorrhagic fever known as Lassa fever. Lack of effective treatments and counter-measures against the virus has resulted in a high mortality rate in its endemic regions. Therefore, in this study, a novel epitope-based vaccine has been designed using the methods of immunoinformatics targeting the glycoprotein and nucleoprotein of the virus. After numerous robust analyses, two CTL epitopes, eight HTL epitopes and seven B-cell epitopes were finally selected for constructing the vaccine. All these most promising epitopes were found to be antigenic, non-allergenic, nontoxic and non-human homolog, which made them suitable for designing the subunit vaccine. Furthermore, the selected T-cell epitopes which were found to be fully conserved across different isolates of the virus, were also considered for final vaccine construction. After that, numerous validation experiments, i.e. molecular docking, molecular dynamics simulation and immune simulation were conducted, which predicted that our designed vaccine should be stable within the biological environment and effective in combating the LASMV infection. In the end, codon adaptation and in silico cloning studies were performed to design a recombinant plasmid for producing the vaccine industrially. However, further in vitro and in vivo assessments should be done on the constructed vaccine to finally confirm its safety and efficacy.Communicated by Ramaswamy H. Sarma.

Therapeutic Potential of Antimicrobial Peptides in Polymicrobial Biofilm-Associated Infections

It is widely recognized that many chronic infections of the human body have a polymicrobial etiology. These include diabetic foot ulcer infections, lung infections in cystic fibrosis patients, periodontitis, otitis, urinary tract infections and even a proportion of systemic infections. The treatment of mixed infections poses serious challenges in the clinic. First, polymicrobial communities of microorganisms often organize themselves as biofilms that are notoriously recalcitrant to antimicrobial therapy and clearance by the host immune system. Secondly, a plethora of interactions among community members may affect the expression of virulence factors and the susceptibility to antimicrobials of individual species in the community. Therefore, new strategies able to target multiple pathogens in mixed populations need to be urgently developed and evaluated. In this regard, antimicrobial or host defense peptides (AMPs) deserve particular attention as they are endowed with many favorable features that may serve to this end. The aim of the present review is to offer a comprehensive and updated overview of studies addressing the therapeutic potential of AMPs in mixed infections, highlighting the opportunities offered by this class of antimicrobials in the fight against polymicrobial infections, but also the limits that may arise in their use for this type of application.

LL-37 and hBD-2 in the gingival crevicular fluid of smokers and nonsmokers with periodontitis

Abstract Introduction The association between smoking and periodontal diseases has been described in clinical and epidemiological studies. Objective The aim of this study was to compare the LL-37 and human β-defensin-2 (hBD-2) levels in crevicular fluid of patients with generalized periodontitis in smokers (S) and nonsmokers (NS). Material and method A total of 35 patients with generalized periodontitis stages III and IV, 15 NS (11 female, 4 male) and 20 S (7 female and 13 male), were included in the study. The evaluated clinical parameters were bleeding on probing (BOP), probing depth (PD) and clinical attachment level (CAL). Enzyme-linked immunosorbent assays were performed to quantify the LL-37 and hBD-2 levels in the gingival crevicular fluid of these patients. The results were analyzed statistically with the level of significance set at 5%. Result In relation to periodontal clinical parameters, no statistically significant difference was observed for BOP and PD between groups S and NS. There was a higher CAL in the S group than in the NS group (p = 0.0095). There was no statistically significant difference between the levels of LL-37 and hBD-2 when comparing groups S and NS (p>0.05). Conclusion It was concluded that smokers have a higher clinical attachment loss than nonsmokers, but that smoking did not influence the levels of LL-37 and hBD-2 in the gingival crevicular fluid in periodontitis.

Block Copolymer Nanoparticles Remove Biofilms of Drug-Resistant Gram-Positive Bacteria by Nanoscale Bacterial Debridement

Biofilms and the rapid evolution of multidrug resistance complicate the treatment of bacterial infections. Antibiofilm agents such as metallic-inorganic nanoparticles or peptides act by exerting antibacterial effects and, hence, do not combat biofilms of antibiotics-resistant strains. In this Letter, we show that the block copolymer DA95B5, dextran- block-poly((3-acrylamidopropyl) trimethylammonium chloride (AMPTMA)- co-butyl methacrylate (BMA)), effectively removes preformed biofilms of various clinically relevant multidrug-resistant Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococci (VRE V583), and Enteroccocus faecalis (OG1RF). DA95B5 self-assembles into core-shell nanoparticles with a nonfouling dextran shell and a cationic core. These nanoparticles diffuse into biofilms and attach to bacteria but do not kill them; instead, they promote the gradual dispersal of biofilm bacteria, probably because the solubility of the bacteria-nanoparticle complex is enhanced by the nanoparticle dextran shell. DA95B5, when applied as a solution to a hydrogel pad dressing, shows excellent in vivo MRSA biofilm removal efficacy of 3.6 log reduction in a murine excisional wound model, which is significantly superior to that for vancomycin. Furthermore, DA95B5 has very low in vitro hemolysis and negligible in vivo acute toxicity. This new strategy for biofilm removal (nanoscale bacterial debridement) is orthogonal to conventional rapidly developing resistance traits in bacteria so that it is as effective toward resistant strains as it is toward sensitive strains and may have widespread applications.

Gingival crevicular fluid levels of human beta-defensin 1 in individuals with and without chronic periodontitis

BACKGROUND AND OBJECTIVE

Human beta-defensins (hBDs) contribute to innate immunity antimicrobial activity. They are also effective in the adaptive immune response and may play a crucial role in the susceptibility to diseases of the oral cavity. This study aimed to evaluate the levels of hBD-1 in the gingival crevicular fluid of individuals with and without chronic periodontitis.

MATERIAL AND METHODS

Twenty periodontally healthy individuals (H) and 20 individuals with chronic periodontitis were recruited. Gingival crevicular fluid samples were collected from: healthy sites (Hh) from periodontally healthy individuals; and healthy sites (Ph), sites with gingivitis (Pg), and sites with periodontitis (Pp) from individuals with periodontitis. The levels of hBD-1 (pg/mL) were measured using enzyme-linked immunosorbent assay. Comparisons of hBD-1 between individuals (H and chronic periodontitis) and among sites (Hh, Ph, Pg, Pp) were performed through hierarchical linear modeling.

RESULTS

Gingival crevicular fluid levels of hBD-1 were: Hh = 229.52 ± 138.96 (median 199.26), Ph = 53.88 ± 58.17 (median 35.75), Pg = 57.11 ± 40.18 (median 39.90) and Pp = 55.31 ± 37.28 (median 54.19). No influence of site diagnosis (level 1; health/gingivitis/periodontitis) was observed; however, individual diagnosis (level 2; health/periodontitis) influenced the levels of hBD-1 (P < .001).

CONCLUSION

Periodontally healthy individuals showed higher gingival crevicular fluid levels of hBD-1 when compared to individuals with chronic periodontitis. This suggests a potential protective role of hBD-1 in the susceptibility to chronic periodontitis.

Antimicrobial peptide gene expression in periodontitis patients: A pilot study

AIM

Antimicrobial peptides (AMPs) are one of the most active components of innate immunity and have characteristics that could place them at the heart of the pathogenesis of periodontal disease. This study investigated differences in the expression of AMP coding genes obtained using a simple harvesting technique, gingival smear, between two groups of patients: chronic periodontitis subjects versus healthy ones.

MATERIALS AND METHODS

Twenty-three patients were enrolled in two groups: 12 were diagnosed with moderate or severe generalized chronic periodontitis, and 11 were diagnosed as clinically healthy. Gingival smears were retrieved and studied using reverse transcription-quantitative PCR (RT-qPCR) after mRNA purification.

RESULTS

Fifteen gene expressions were obtained using real-time RT-qPCR. Three AMP genes, histatin 3 (HTN3), α-defensin 4 (DEFA4) and lysozyme C (LYZ), presented different expression levels in periodontitis patients compared with healthy subjects. The relative expression level of DEFA4 appeared to be a protective factor against periodontitis.

CONCLUSION

Gingival smears studied by RT-qPCR may be used to assess the expression of AMPs coding genes. A lack of expression of DEFA4 could be a potential indicator of periodontitis status.

Transplantation of periodontal ligament cell sheets expressing human β‑defensin‑3 promotes anti‑inflammation in a canine model of periodontitis

Periodontitis is a chronic oral inflammatory disease caused by microorganisms. Human β-defensin-3 (HBD-3) is an endogenous antimicrobial peptide that inhibits a broad spectrum of microorganisms. Cell sheet technology has been widely applied in tissue and organ reconstructions. In the current study, it was aimed to investigate the anti-inflammatory effect of periodontal tissue engineered by HBD-3 gene-modified periodontal ligament cell (PDLC) sheets, and to identify a suitable method of promoting the regeneration of periodontal tissues. Western blot analysis and antimicrobial tests were used to confirm the expression of HBD-3. The effect of the cell sheets on anti-inflammatory activity and bone remodeling in a dog model of periodontitis was demonstrated by immunohistochemistry. The results demonstrated that the transfected PDLCs stably expressed HBD-3. Periodontal pathogens were susceptible to the antimicrobial activity of the cell sheets. In addition, the cell sheets relieved the bone resorption caused by inflammation in the in vivo model. HBD-3 may potentially be applied in the treatment of periodontitis and may function as osteogenic promoter via its anti-inflammatory effect.

Human β-defensin 3 inhibits periodontitis development by suppressing inflammatory responses in macrophages

Human β-defensin 3 (hBD3) is a cationic peptide with immunomodulatory effects on both innate and acquired immune responses. Periodontitis, an inflammatory disease that extends deep into periodontal tissues, causes the loss of supporting structures around the tooth. The present study assessed the effects of hBD3 as a monotherapy for periodontitis in mice and explored its potential mechanism. In vivo, hBD3 inhibited the levels of tumour necrosis factor (TNF)-α, interleukin-6, and matrix metalloprotease-9 in periodontium exposed to Porphyromonas gingivalis (P.g) in a mouse periodontitis model; reduced osteoclast formation and lower alveolar bone loss were also observed. In addition, hBD3 was related to the expression of polarization signature molecules in circulating monocytes. In vitro, hBD3 notably suppressed the production of TNF-α and interleukin-6 in RAW 264.7 cells stimulated by the lipopolysaccharide of P.g. Moreover, hBD3 attenuated polarization of RAW 264.7 cells into the M1 phenotype, with reduced activation of nuclear factor-κB signal transduction. In conclusion, hBD3 exhibits potent anti-periodontitis properties both in vitro and in vivo, and this effect may be correlated to inhibition of the nuclear factor-κB pathway and macrophage polarization.

Expression and antimicrobial character of cells transfected with human β‑defensin‑3 against periodontitis‑associated microbiota in vitro

Periodontitis is an oral chronic inflammatory disease induced by microorganisms that can destroy tooth-supporting structures. Human β-defensin-3 (HBD-3) is a type of endogenous antimicrobial peptide that inhibits a broad spectrum of microorganisms. The objectives of the present study were to transfect human periodontal ligament cells (HPDLCs) and human bone marrow stromal cells (HBMSCs) with lentivirus containing the HBD-3 gene, determine the transfection efficiency, and investigate the antimicrobial activity of the experimental cells against periodontal pathogens. Fluorescence microscopy was used to calculated the transfection efficiency. Western blot analysis and ELISA were conducted to confirm the expression of HBD-3 at the protein level. The effect of the HBD-3 gene on the antimicrobial activity of the cells were demonstrated by antimicrobial tests. The results of the present study demonstrated that the transfected HPDLCs and HBMSCs stably expressed HBD-3. In addition, periodontal pathogens and caries-causing bacteria were susceptible to the antimicrobial activity of the cells. Both HPDLCs and HBMSCs hold potential for use as seeding cells in cell- and gene-based therapies for periodontal disease. The lentiviral vector containing HBD-3 resulted in broad-spectrum antimicrobial activity against a variety of oral organisms, and could potentially be applied in the treatment of oral infectious diseases, including periodontitis.

Potassium is a key signal in host-microbiome dysbiosis in periodontitis

Dysbiosis, or the imbalance in the structural and/or functional properties of the microbiome, is at the origin of important infectious inflammatory diseases such as inflammatory bowel disease (IBD) and periodontal disease. Periodontitis is a polymicrobial inflammatory disease that affects a large proportion of the world's population and has been associated with a wide variety of systemic health conditions, such as diabetes, cardiovascular and respiratory diseases. Dysbiosis has been identified as a key element in the development of the disease. However, the precise mechanisms and environmental signals that lead to the initiation of dysbiosis in the human microbiome are largely unknown. In a series of previous in vivo studies using metatranscriptomic analysis of periodontitis and its progression we identified several functional signatures that were highly associated with the disease. Among them, potassium ion transport appeared to be key in the process of pathogenesis. To confirm its importance we performed a series of in vitro experiments, in which we demonstrated that potassium levels a increased the virulence of the oral community as a whole and at the same time altering the immune response of gingival epithelium, increasing the production of TNF-α and reducing the expression of IL-6 and the antimicrobial peptide human β-defensin 3 (hBD-3). These results indicate that levels of potassium in the periodontal pocket could be an important element in of dysbiosis in the oral microbiome. They are a starting point for the identification of key environmental signals that modify the behavior of the oral microbiome from a symbiotic community to a dysbiotic one.

Homeostasis of the human microbiome plays a key role in maintaining the healthy status of the human body. Changes in composition and function of the human microbiome (dysbiosis) are at the origin of important infectious inflammatory diseases such as inflammatory bowel disease (IBD) and periodontal disease. However, the environmental elements that trigger the development of dysbiotic diseases are largely unknown. In previous studies, using community-wide transcriptome analysis, we identified ion potassium transport as one of the most important functions in the pathogenesis of periodontitis and its progression. Here, we confirm with a series of in vitro experiments that potassium can act as an important signal in the dysbiotic process inducing pathogenesis in the oral microbiome and altering the host response in front of the microbial challenge that could lead to microbial immune subversion. Our study provides new insights into the important role that ion potassium plays a signal in oral dysbiosis during periodontitis.

Benefits of Bifidobacterium animalis subsp. lactis Probiotic in Experimental Periodontitis

BACKGROUND

This study evaluates effects of topical administration of probiotic bacteria of the genus Bifidobacterium on experimental periodontitis (EP) in rats.

METHODS

Thirty-two rats were divided into groups C (control; without EP), EP (EP only), C-HN019 (control+probiotic), and EP-HN019 (EP+probiotic). On day 0 of the experiment, animals of groups EP and EP-HN019 received cotton ligatures around mandibular first molars (MFMs). In groups C-HN019 and EP-HN019, 1 mL of suspensions containing Bifidobacterium animalis subsp. lactis (B. lactis) HN019 was topically administered in the subgingival region of MFMs on days 0, 3, and 7. In groups C and EP, topical administrations were performed using a sham suspension (without probiotic). All animals were euthanized at day 14. Gingival tissue, hemimandibles, and oral biofilm were collected. Data were statistically analyzed (P <0.05).

RESULTS

Group EP presented greater bone porosity, trabecular separation, and connective tissue attachment loss (CTAL) as well as reduced bone volume than all other groups (P <0.05). In group EP-HN019, there were greater proportions of Actinomyces and Streptococcus-like species and lower proportions of Veillonella parvula, Capnocytophaga sputigena, Eikenella corrodens, and Prevotella intermedia-like species than group EP. Group EP-HN019 presented greater expressions of osteoprotegerin and β-defensins than group EP (P <0.05). Group EP presented greater levels of interleukin-1β and receptor activator of nuclear factor-kappa B ligand than group EP-HN019 (P <0.05).

CONCLUSION

Topical use of B. lactis HN019 promotes a protective effect against alveolar bone loss and CTALs attributable to EP in rats, modifying immunoinflammatory and microbiologic parameters.

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.

Antimicrobial peptides and their interaction with biofilms of medically relevant bacteria

Biofilm-associated infections represent one of the major threats of modern medicine. Biofilm-forming bacteria are encased in a complex mixture of extracellular polymeric substances (EPS) and acquire properties that render them highly tolerant to conventional antibiotics and host immune response. Therefore, there is a pressing demand of new drugs active against microbial biofilms. In this regard, antimicrobial peptides (AMPs) represent an option taken increasingly in consideration. After dissecting the peculiar biofilm features that may greatly affect the development of new antibiofilm drugs, the present article provides a general overview of the rationale behind the use of AMPs against biofilms of medically relevant bacteria and on the possible mechanisms of AMP-antibiofilm activity. An analysis of the interactions of AMPs with biofilm components, especially those constituting the EPS, and the obstacles and/or opportunities that may arise from such interactions in the development of new AMP-based antibiofilm strategies is also presented and discussed. This article is part of a Special Issue entitled: Antimicrobial Peptides edited by Karl Lohner and Kai Hilpert.

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.

Relationship between expression of human gingival beta-defensins and levels of periodontopathogens in subgingival plaque

BACKGROUND AND OBJECTIVE

Human beta-defensins (hBDs) are a group of antimicrobial peptides important in epithelial innate immunity, and their differential expression is associated with periodontal diseases. The aim of this study was to explore relationships among hBDs, total subgingival bacteria and periodontopathogens in healthy subjects and in patients with chronic periodontitis.

MATERIAL AND METHODS

The periodontal clinical parameters of 29 healthy subjects and 25 patients with chronic periodontitis were recorded. The relative expression of hBD1, hBD2 and hBD3 genes in gingival biopsies was measured using real-time PCR. The numbers of total bacteria and of Treponema denticola, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Fusobacterium nucleatum and Tannerella forsythia in subgingival plaque were quantified by real-time PCR. Data were analyzed using the Mann-Whitney U-test and Spearman's rank correlation test.

RESULTS

No significant differences in expression of the hBD genes were found between the group of healthy subjects and the group of patients with chronic periodontitis. Total bacteria and T. denticola were detected in all participants. F. nucleatum and T. forsythia were detected in all patients with chronic periodontitis and in 86.21% and 51.72%, respectively, of healthy volunteers. P. gingivalis and A. actinomycetemcomitans were detected in 24.14% and 17.24%, respectively, of the healthy group and in 84.00% and 12.00%, respectively, of the chronic periodontitis group. The prevalence of all bacteria, except A. actinomycetemcomitans, was significantly higher in the group of patients with chronic periodontitis than in the group of healthy subjects (p < 0.05). A significant, negative correlation was observed between total bacteria and hBD-2 (r = -0.384, p = 0.011). Upon analyzing the data in different groups, total bacteria and hBD-2 were significantly correlated (r = -0.492, p = 0.026) only in the group of healthy subjects.

CONCLUSION

The negative correlations between hBD-2 and total bacteria, especially in the group of healthy subjects, indicate that hBDs may play an important role by limiting an increase of bacterial load at the initial stage of periodontitis.

Levels of salivary immunoglobulins and periodontal evaluation in smoking patients

Objective

The aim of this study was to assess the level of salivary immunoglobulins and periodontal status in smokers and non-smokers.

Materials and methods

Unstimulated saliva of 30 subjects (mean age 24.2 ± 3.5 years) who were smokers (test group) and of 30 subjects (mean age 25.3 ± 3.8 years) who were non-smokers (control group) was collected and centrifugated; IgA, IgG, and IgM were measured with the colorimetric immunoenzymatic method. Moreover, the following periodontal clinical parameters were recorded for each subject: plaque index (PI), gingival index (GI), probing depth (PD), and clinical attachment level (CAL).

Results

A significantly (p< 0.05) lower Ig level was observed in smoking patients (IgA: 20.0 ± 1.2 mg/dl; IgM: 19.5 ± 1.6 mg/dl; IgG: 8.1 ± 1.4 mg/dl) compared to levels in the non-smoking control group (IgA: 234.1 ± 65.2 mg/dl; IgM: 121.0 ± 31.7 mg/dl; IgG: 1049.4 ± 102 mg/dl). In the test group, PI (2.2 ± 0.3), GI (2.4 ±0.5), PD (49.3 ± 9.2%), and CAL (49.3 ± 4.6%) were higher (p< 0.05) than those observed in the control group (PI: 0.8 ± 0.4; GI: 0.7 ± 0.3; PD: 10.6 ± 2.4%; CAL: 3.1 ± 0.8%).

Conclusion

Smoking subjects showed lower levels of salivary IgA, IgG, and IgM and a worse periodontal condition than non-smoking subjects. On the base of our study, as smoking subjects also had lower levels of IgA, IgG, and IgM in their saliva than non-smoking subjects, despite the fact that there is little evidence that the salivary Igs have a protective action against periodontitis and that the whole saliva does not result in whole from the salivary glands, it can be concluded that the deteriorated periodontal health conditions of these patients can be attributed in part to a lowering of the host’s defense due to a decrease in the quantity of Igs in salivary fluid.

The expression of hBDs in the gingival tissue and keratinocytes from healthy subjects and periodontitis patients

OBJECTIVE

Although the secretion of antimicrobial peptides in gingival tissue and isolated cells has been reported, the induction of human β-defensins (hBDs) in epithelial cells from the periodontitis patients was not stated before. This study aimed to compare the secretion of hBDs in gingival epithelial cells from periodontitis patients and healthy controls.

DESIGN

Firstly, gingival biopsies were obtained from chronic periodontitis patients and healthy controls and the hBDs expression level in gingival tissues was quantified. Then the epithelial cells from periodontitis patients and healthy controls were isolated and challenged with different concentrations of tumour necrosis factor-alpha (TNFα). The hBDs expression level was also quantified after induction. At last, to identify the molecular pathways involved in hBDs induction, the isolated cells were incubated with NF-kB or MAPK inhibitor before TNFα induction.

RESULTS

Higher hBDs expression was found in gingival tissues from healthy controls. The in vitro experiments demonstrated that the hBD-2 expression in gingival epithelial cells from periodontitis patients can be induced by TNFα at lower dose, while the optimum expression level was much lower. The basal hBD-3 mRNA expression was much higher in cells from periodontitis patients. The molecular pathways involved in the responses to the inflammatory cytokine in patients and healthy controls were the same.

CONCLUSIONS

The epithelial cells from periodontitis patients are more prone to recognize and respond to TNFα to produce hBD-2. The basal expression of hBD-3 in keratinocytes from periodontitis patients suggested that hBD-3 may play an important role in the immunological reaction against periodontitis.

Green tea extract and its major constituent, epigallocatechin-3-gallate, induce epithelial beta-defensin secretion and prevent beta-defensin degradation by Porphyromonas gingivalis

BACKGROUND AND OBJECTIVE

Antimicrobial peptides, such as beta-defensins, secreted by gingival epithelial cells, are thought to play a major role in preventing periodontal diseases. In the present study, we investigated the ability of green tea polyphenols to induce human beta-defensin (hBD) secretion in gingival epithelial cells and to protect hBDs from proteolytic degradation by Porphyromonas gingivalis.

MATERIAL AND METHODS

Gingival epithelial cells were treated with various amounts (25-200 μg/mL) of green tea extract or epigallocatechin-3-gallate (EGCG). The secretion of hBD1 and hBD2 was measured using ELISAs, and gene expression was quantified by real-time PCR. The treatments were also carried out in the presence of specific kinase inhibitors to identify the signaling pathways involved in hBD secretion. The ability of green tea extract and EGCG to prevent hBD degradation by proteases of P. gingivalis present in a bacterial culture supernatant was evaluated by ELISA.

RESULTS

The secretion of hBD1 and hBD2 was up-regulated, in a dose-dependent manner, following the stimulation of gingival epithelial cells with a green tea extract or EGCG. Expression of the hBD gene in gingival epithelial cells treated with green tea polyphenols was also increased. EGCG-induced secretion of hBD1 and hBD2 appeared to involve extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase. Lastly, green tea extract and EGCG prevented the degradation of recombinant hBD1 and hBD2 by a culture supernatant of P. gingivalis.

CONCLUSION

Green tea extract and EGCG, through their ability to induce hBD secretion by epithelial cells and to protect hBDs from proteolytic degradation by P. gingivalis, have the potential to strengthen the epithelial antimicrobial barrier. Future clinical studies will indicate whether these polyphenols represent a valuable therapeutic agent for treating/preventing periodontal diseases.

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.

Associations between vaginal bacteria and levels of vaginal defensins in pregnant women

OBJECTIVE

We evaluated vaginal defensin concentrations and levels of bacterial vaginosis-associated bacterial species in pregnant women.

STUDY DESIGN

Self-collected vaginal swabs from 2 visits during pregnancy were tested with quantitative polymerase chain reaction for 9 bacterial species. Beta defensins 2-3 and alpha defensins 1-3 were measured by enzyme-linked immunosorbent assay.

RESULTS

Our 126 participants were primarily African American (60%), had a mean gestational age at enrollment of 10 ± 3 weeks and at follow-up visit of 25 ± 6 weeks. At enrollment, the prevalence of bacterial vaginosis was 74% (94/126 women), which decreased to 60% (75/126 specimens) at follow-up visit. At enrollment, beta defensin 3 concentrations were significantly lower in women with bacterial vaginosis (2.64 ± 0.91 vs 3.25 ± 0.99 log(10) pg/mL; P = .003). Higher concentrations of Atopobium vaginae, bacterial vaginosis-associated bacteria1 and 2 were associated with significantly lower concentrations of beta defensin 3 (P < .01).

CONCLUSION

Bacterial vaginosis was associated with lower vaginal concentrations of beta defensin 3, but not beta defensin 2 or alpha defensins 1-3, in pregnant women.

Gingival crevicular fluid levels of human beta-defensins 1 and 3 in subjects with periodontitis and/or type 2 diabetes mellitus: a cross-sectional study

BACKGROUND AND OBJECTIVE

Human β-defensins (hBDs) have a strong antibacterial action against various microorganisms, especially periodontal pathogens. The aim of this study was to compare the total levels of hBD-1 and hBD-3 in the gingival crevicular fluid of healthy patients with gingivitis (HG), healthy patients with chronic periodontitis (HP), patients with type 2 diabetes mellitus (DM) and gingivitis (DM2G) and patients with type 2 DM and chronic periodontitis (DM2P).

MATERIAL AND METHODS

A total of 80 patients were included: 20 HG, 20 HP, 20 DM2G and 20 DM2P. The levels of hBD-1 and hBD-3 in gingival crevicular fluid were measured using ELISA.

RESULTS

The DM2P group had significantly higher periodontal clinical parameters at sites from which gingival crevicular fluid was collected compared with the other groups. The HG group had significantly lower periodontal clinical parameters within the gingival crevicular fluid-collected sites than did the HP, DM2G and DM2P groups. The gingival crevicular fluid of the DM2P group had significantly higher levels of total hBD-1 and hBD-3 than did that of the other groups; the hBD-1 and hBD-3 levels were significantly higher in the gingival crevicular fluid of the DM2G group than in that of the the non-DM type 2 groups (HG and HP). The gingival crevicular fluid of the HP group had significantly higher levels of total hBD-1 and hBD-3 in comparison with that of the HG group.

CONCLUSION

As a result of the observed vascular and cell activity changes that occur within patients diagnosed with DM, periodontal diseases become more severe. These changes hinder the migration and the ability of chemotactic factors and leukocytes to protect periodontal tissues from the effects of microorganisms. In order to eliminate microorganisms, the epithelial cells in patients with DM may release more hBD-1 and hBD-3 into the gingival crevicular fluid. Determining the amount of hBD-1 and hBD-3 in the gingival crevicular fluid of patients with and without DM will help to elucidate the relationship among hBD-1, hBD-3, DM and periodontal disease.

Influence of periodontal status and periodontopathogens on levels of oral human β-defensin-2 in saliva

BACKGROUND

Expression patterns of human β-defensin-2 (HBD-2) mRNA or HBD-2 protein concentration and periodontal diseases have been a focus of scientific research. This study compares the salivary levels of HBD-2 protein concentration of healthy patients and patients with gingivitis and chronic periodontitis (CP) and correlates these levels with the presence of periodontopathogens.

METHODS

A total of 89 patients were enrolled in this study: 31 periodontally healthy, 27 with gingivitis, and 31 with CP. Plaque and gingival indices, probing depth, and clinical attachment level were measured. The presence of Campylobacter rectus, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, and Prevotella intermedia was evaluated qualitatively by conventional polymerase chain reaction. HBD-2 quantification in saliva was performed using an immune enzymatic assay. Frequency of periodontopathogens and HBD-2 protein concentration was assessed. Association between HBD-2 protein concentration (≥100 pg/mL) and the simultaneous presence of one to two, three to four, or five to six periodontopathogens was tested.

RESULTS

Although periodontally healthy individuals and patients with gingivitis showed similar HBD-2 levels, the CP group displayed an increased level of HBD-2. P. gingivalis, P. intermedia, T. forsythia, and T. denticola were more prevalent in CP; however, their mere presence was not related to the increased levels of HBD-2 (Pearson correlation and multinomial logistic regression model).

CONCLUSIONS

Salivary HBD-2 protein concentration was higher in patients with CP compared with healthy individuals or patients with gingivitis. These different protein concentrations were not related to the frequency of periodontopathogens. Clinical inflammatory profile had a higher impact on salivary HBD-2 levels than bacteria.

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.

Gingipains produced by Porphyromonas gingivalis ATCC49417 degrade human-β-defensin 3 and affect peptide's antibacterial activity in vitro

Porphyromonas gingivalis, one of the major pathogen associated with periodontitis, is a highly proteolytic bacterial species. Production of proteases is a common microbial virulence factor that enables the destruction of host tissues and evasion from host defense mechanisms. Antimicrobial peptides are important effector molecules of the innate immune system with a broad range of antimicrobial and immunoregulatory activities. We and others have previously demonstrated that P. gingivalis is relatively resistant to the bactericidal activity of the human β-defensin 3 (hBD3). In this study, ability of proteases released by the pathogenic strain of P. gingivalis ATCC 49417 to degrade hBD3 and to affect the antibacterial properties of the peptide was assessed. P. gingivalis culture supernatants (CS) were found to degrade hBD3 in a concentration- and time-dependent manner. Such degradation was mainly due to the activity of Arg and Lys-gingipains, as pretreatment of CS with inhibitors selective for this class of proteases abolished CS ability to degrade hBD3. Importantly, preincubation of hBD3 with CS reduced peptide's antibacterial activity against a susceptible strain of Staphylococcus aureus, while the presence of gingipain inhibitors in the bactericidal assay increased P. gingivalis susceptibility to hBD3. Altogether these results suggest that gingipains may have a role in the resistance of P. gingivalis ATCC 49417 to hBD3.

Effect of human beta-defensin-3 on the proliferation of fibroblasts on periodontally involved root surfaces

Human beta-defensin-3 (HBD-3) has versatile antibacterial activity against oral bacteria and can promote the proliferation of fibroblasts. The goal of the present study was to investigate the effect of HBD-3 on attachment and proliferation of periodontal ligament cells (PDL) onto the periodontitis affected root surfaces. PDL cells were seeded onto healthy and diseased root specimens with scaling and root planing (SRP), SRP & HBD-3 (100 ng/ml), or SRP & HBD-3 (200 ng/ml) treatment for 1, 3, and 7 days incubation. The results showed that HBD-3, especially in the 200 ng/ml group, significantly promoted fibroblast attachment and proliferation onto the diseased root surfaces. The cell number in the HBD-3 group was much greater than in the group treated with SRP alone. On day 7, the cells in the HBD-3 were well-spread and formed a network similar to those on the surfaces of the healthy root specimens. These results suggest that HBD-3 could play an important role in antibacterial activity and fibroblast proliferation, thus promoting periodontal regeneration. Meanwhile, HBD-3 might act as a potent regeneration-promoter in infectious diseases.