KR-12-a5 is a non-cytotoxic agent with potent antimicrobial effects against oral pathogens.

This study evaluated the cytotoxicity and antimicrobial activity of analogs of cationic peptides against microorganisms associated with endodontic infections. L-929 fibroblasts were exposed to LL-37, KR-12-a5 and hBD-3-1CV and chlorhexidine (CHX, control), and cell metabolism was evaluated with MTT. The minimal inhibitory concentration (MIC) and the minimal bactericidal/fungicidal concentration (MBC/MFC) of the peptides and CHX were determined against oral pathogens associated with endodontic infections. Enterococcus faecalis and Streptococcus mutans biofilms were cultivated in bovine dentin blocks, exposed to different concentrations of the most efficient antimicrobial peptide and analyzed by confocal laser scanning microscopy. CHX and peptides affected the metabolism of L-929 at concentrations > 31.25 and 500 µg ml-1, respectively. Among the peptides, KR-12-a5 inhibited growth of both the microorganisms tested with the lowest MIC/MBC/MFC values. In addition, KR-12-a5 significantly reduced E. faecalis and S. mutans biofilms inside dentin tubules. In conclusion, KR-12-a5 is a non-cytotoxic agent with potent antimicrobial and anti-biofilm activity against oral pathogens associated with endodontic infections.

Comparison of two different methods for detecting periodontal pathogenic bacteria

Aim: To perform a comparative analysis between two methods for detecting Porphyromonas gingivalis, Tannerella forsythia and Porphyromonas endodontalis in periodontal plaque samples. Methods: The study sample consisted of twenty systemically healthy patients showing generalized chronic periodontitis. The subgingival samples for microbiological analysis were collected before (baseline) and 60 days after a basic periodontal therapy from 30 non-adjacent affected sites (Probing Depth (PD): 5-7 mm, Clinical Attachment Loss (CAL) ≥ 5 mm, positive for Bleeding on Probing (BOP)). Microbiological analysis was performed by PCR and qPCR. To allow a comparative analysis between both methods, qPCR was divided in three different scores (score 2: presence of more than 100 bacteria; score 1: presence of 10-100 bacteria, and score 0: absence of bacteria), in accordance to DNA quantity, while for PCR two scores were assigned: presence or absence of bacteria. Results: qPCR demonstrated higher sensitivity in the detection of these pathogens compared with PCR when scores 1 and 2 were considered positive. However, when only score 2 was considered positive, PCR and qPCR showed better agreement. Conclusions: qPCR demonstrated higher sensitivity than conventional PCR for detection of low numbers of microorganisms and can be useful for the quantification of periodontopathogens. (AU)

Cytotoxicity and the effect of cationic peptide fragments against cariogenic bacteria under planktonic and biofilm conditions.

This study evaluated the cytotoxicity and effect of fragments derived from three oral cationic peptides (CP): LL-37, D6-17 and D1-23 against cariogenic bacteria under planktonic and biofilm conditions. For cytotoxicity analysis, two epithelial cell lines were used. The minimum inhibitory concentration and the minimal bactericidal concentration were determined for the CP fragments and the control (chlorhexidine-CHX) against cariogenic bacteria. The fractional inhibitory concentration was obtained for the combinations of CP fragments on Streptococcus mutans. Biofilm assays were conducted with the best antimicrobial CP fragment against S. mutans. The results indicated that D6-17 was not cytotoxic. D1-23, LL-37 and CHX were not cytotoxic in low concentrations. D1-23 presented the best bactericidal activity against S. mutans, S. mitis and S. salivarius. Combinations of CP fragments did not show a synergic effect. D1-23 presented a higher activity against S. mutans biofilm than CHX. It was concluded that D1-23 showed a substantial effect against cariogenic bacteria and low cytotoxicity.

Green tea extract and its major constituent epigallocatechin-3-gallate inhibit growth and halitosis-related properties of Solobacterium moorei.

BACKGROUND: Solobacterium moorei is a volatile sulfide compound (VSC)-producing Gram-positive anaerobic bacterium that has been associated with halitosis. The aim of this study was to investigate the effects of green tea extract and its major constituent epigallocatechin-3-gallate (EGCG) on growth and several halitosis-related properties of S. moorei. METHODS: A microplate dilution assay was used to determine the antibacterial activity of green tea extract and EGCG against S. moorei. Their effects on bacterial cell membrane integrity were investigated by transmission electron microscopy and a fluorescence-based permeability assay. Biofilm formation was quantified by crystal violet staining. Adhesion of FITC-labeled S. moorei to oral epithelial cells was monitored by fluorometry. The modulation of ß-galactosidase gene expression in S. moorei was evaluated by quantitative RT-PCR. RESULTS: The green tea extract as well as EGCG inhibited the growth of S. moorei, with MIC values of 500 and 250 µg/ml, respectively. Transmission electron microscopy analysis and a permeabilization assay brought evidence that the bacterial cell membrane was the target of green tea polyphenols. Regarding the effects of green tea polyphenols on the S. moorei colonization properties, it was found that biofilm formation on EGCG-treated surfaces was significantly affected, and that green tea extract and EGCG can cause the eradication of pre-formed S. moorei biofilms. Moreover, both the green tea extract and EGCG were found to reduce the adherence of S. moorei to oral epithelial cells. The ß-galactosidase activity of S. moorei, which plays a key role in VSC production, was dose-dependently inhibited by green tea polyphenols. In addition, EGCG at ½ MIC significantly decreased the ß-galactosidase gene expression. CONCLUSION: Our study brought evidence to support that green tea polyphenols possess a number of properties that may contribute to reduce S. moorei-related halitosis. Therefore, these natural compounds may be of interest to be used to supplement oral healthcare products.

Synergistic anti-inflammatory activity of the antimicrobial peptides human beta-defensin-3 (hBD-3) and cathelicidin (LL-37) in a three-dimensional co-culture model of gingival epithelial cells and fibroblasts.

Given the spread of antibiotic resistance in bacterial pathogens, antimicrobial peptides that can also modulate the immune response may be a novel approach for effectively controlling periodontal infections. In the present study, we used a three-dimensional (3D) co-culture model of gingival epithelial cells and fibroblasts stimulated with Aggregatibacter actinomycetemcomitans lipopolysaccharide (LPS) to investigate the anti-inflammatory properties of human beta-defensin-3 (hBD-3) and cathelicidin (LL-37) and to determine whether these antimicrobial peptides can act in synergy. The 3D co-culture model composed of gingival fibroblasts embedded in a collagen matrix overlaid with gingival epithelial cells had a synergistic effect with respect to the secretion of IL-6 and IL-8 in response to LPS stimulation compared to fibroblasts and epithelial cells alone. The 3D co-culture model was stimulated with non-cytotoxic concentrations of hBD-3 (10 and 20 µM) and LL-37 (0.1 and 0.2 µM) individually and in combination in the presence of A. actinomycetemcomitans LPS. A multiplex ELISA assay was used to quantify the secretion of 41 different cytokines. hBD-3 and LL-37 acted in synergy to reduce the secretion of GRO-alpha, G-CSF, IP-10, IL-6, and MCP-1, but only had an additive effect on reducing the secretion of IL-8 in response to A. actinomycetemcomitans LPS stimulation. The present study showed that hBD-3 acted in synergy with LL-37 to reduce the secretion of cytokines by an LPS-stimulated 3D model of gingival mucosa. This combination of antimicrobial peptides thus shows promising potential as an adjunctive therapy for treating inflammatory periodontitis.

Subinhibitory concentrations of triclosan promote Streptococcus mutans biofilm formation and adherence to oral epithelial cells.

Triclosan is a general membrane-active agent with a broad-spectrum antimicrobial activity that is commonly used in oral care products. In this study, we investigated the effect of sub-minimum inhibitory concentrations (MICs) of triclosan on the capacity of the cariogenic bacterium Streptococcus mutans to form biofilm and adhere to oral epithelial cells. As quantified by crystal violet staining, biofilm formation by two reference strains of S. mutans was dose-dependently promoted, in the range of 2.2- to 6.2-fold, by 1/2 and 1/4 MIC of triclosan. Observations by scanning electron microscopy revealed the presence of a dense biofilm attached to the polystyrene surface. Growth of S. mutans in the presence of triclosan at sub-MICs also increased its capacity to adhere to a monolayer of gingival epithelial cells. The expression of several genes involved in adherence and biofilm formation in S. mutans was investigated by quantitative RT-PCR. It was found that sub-MICs of triclosan significantly increased the expression of comD, gtfC, and luxS, and to a lesser extent of gtfB and atlA genes. These findings stress the importance of maintaining effective bactericidal concentrations of therapeutic triclosan since sub-MICs may promote colonization of the oral cavity by S. mutans.

Efeito antimicrobiano e modulador da resposta imune dos peptídeos hBD-3 e LL-37 e dos polifenóis do chá verde e do cranberry / Antimicrobial and immune regulatory activity of the peptides hBD-3, LL-37 and the polyphenols from cranberry and green tea

Os peptídeos antimicrobianos como por exemplo a catelicina (LL-37) e as defensinas humanas (hBD-1, hBD-2 e a hBD-3) são considerados antibióticos endógenos com importante papel na prevenção das doenças periodontais, devido a sua capacidade de regulação da resposta imune, sendo que os mesmos podem ser degradados pelos periodontopatógenos. Terapias que aumentem a produção destes peptídeos pelas próprias células do organismo, assim como a associação destes peptídeos com compostos naturais os quais possam agir em sinergismo na regulação da resposta imune, podem ser considerados novas estratégias para o melhor controle das doenças periodontais. Portanto os objetivos deste estudo in vitro foram: i) Avaliar a capacidade do extrato do chá verde (Camellia sinensis) e do seu polifenol, o EGCG, sobre a expressão gênica de hBD-1 e hBD-2 pelas células epiteliais gengivais (B11), sobre a degradação das mesmas frente ao P. gingivalis, ii) Através da utilização do modelo 3D de co-cultura celular, avaliar a capacidade antiinflamatória dos peptídeos hBD-3 e LL-37 quando em associação sobre a produção de citocinas, quimiocinas e fatores de crescimento, iii) Avaliar a capacidade anti-inflamatória da associação do EGCG e do polifenol proveniente do cranberry, o AC-PACs, com o peptídeo LL-37 sobre a produção de citocinas, quimiocinas e fatores de crescimento em modelo de co-cultura celular. As células epiteliais gengivais (B11) foram estimuladas com o extrato do chá verde e com o EGCG na presença e ausência de inibidores específicos. A produção e expressão gênica de hBD-1 e hBD-2 foram quantificados respectivamente pelas técnica de ELISA e qPCR. A capacidade do extrato do chá verde e do EGCG em proteger a degradação de hBDs pelo P. gingivalis foi mensurado através da técnica de ELISA. Foi desenvolvido um modelo em 3D de co-cultura de fibroblastos gengivais embebidos em uma matriz de colágeno com células epiteliais gengivais semeadas em sua superfície, no qual observou-se efeito sinérgico das células na secreção de IL-6 e IL-8 em resposta ao estímulo com LPS de A. actinomycetemcomitans (1 µg/ml) quando comparados as células individuais. Em seguida o modelo em 3D de co-cultura celular na presença no LPS de A. actinomycetemcomitans foi estimulado com: i) hBD-3 (10 and 20 µM) e LL-37 (0.1 and 0.2 µM), ii) EGCG (1 e 5 µg/ml) e LL-37 (0.1 and 0.2 µM) e iii) AC-PACs (25 e 50 µg/ml) e LL-37 (0.1 and 0.2 µM), individualmente e em associação. Foi utilizada a técnica de ELISA Multiplex para quantificar 41 diferentes citocinas, quimiocinas, fatores de crescimentos e 13 diferentes MMPs e TIMPs. Os resultados demonstraram que: i) o extrato do chá verde e o EGCG aumentaram a produção e a expressão gênica de hBD-1 e hBD-2 pelas células epiteliais de uma maneira dose-dependente, e foram capazes de prevenir a degradação das hBD-1 e hBD-2 recombinantes pelo sobrenadante de P. gingivalis, ii) o peptídeo hBD-3 em associação com o LL37 mostrou efeito sinérgico na diminuição da produção de GRO-α, G-CSF, IP-10, IL-6, e MCP1, entretanto teve apenas efeito aditivo na redução da produção de IL-8 em resposta ao estímulo com LPS de A. actinomycetemcomitans, iii) a associação do peptídeo LL-37 com o EGCG e com o AC-PACs mostraram efeito sinérgico na redução da produção de GRO-α, G-CSF e IL-6 em resposta ao estímulo com LPS de A. actinomycetemcomitans. Portanto os peptídeos antimicrobianos hBD-3 e LL-37, assim como o extrato do chá verde, o EGCG e o AC-PACs por demonstrarem capacidade de regular a produção de citocinas inflamatórias, induzir a produção de defensinas pelas próprias células e proteger as defensinas da degradação pelo P. gingivalis surgem como promissores alternativas para terapias adjuntas ao tratamento periodontal convencional. Entretanto estudos clínicos futuros são necessários para avaliar o papel dos peptídeos e dos compostos naturais na cavidade oral e na proteção dos tecidos periodontais frente à uma agressão

The antimicrobial peptides LL-37, hBD-1, hBD-2 and hBD-3 are considered an endogenous antibiotic, with important role in the prevention of periodontal diseases due to their ability to regulate the immune response. However those peptides could be degraded by periodontal pathogens. Therefore, therapies able to up regulate the secretion of those peptides by human cells, and the association of antimicrobial peptides with natural compounds, which may act in synergism to modulate the immune response, may be a novel approach for effectively controlling periodontal diseases. The aim of this in vitro study were: i) investigate the ability of green tea extract and EGCG to induce hBD-1 and hBD-2 secretion and gene expression by gingival epithelial cells (B11) and to protect hBDs from degradation by P. gingivalis, ii) A 3D co-culture model of gingival epithelial cells and fibroblasts stimulated with A. actinomycetemcomitans LPS (1 µg/ml) were used to investigated the anti-inflammatory properties of the hBD-3, LL-37, ACPACs and EGCG and to determine whether LL-37 acts in synergy with AC-PACs, EGCG and hBD-3. Gingival epithelial cells were stimulated with green tea extract or EGCG in the presence and absence of specific inhibitors. The secretion and gene expression of hBD-1 and hBD-2 was respectively measured by ELISA and qPCR. The ability of green tea extract and EGCG to prevent hBDs degradation by P. gingivalis present in a bacterial culture supernatant was evaluated by ELISA. A 3D co-culture model composed of gingival fibroblasts embedded in a collagen matrix overlaid with gingival epithelial cells had a synergistic effect with respect to the secretion of IL-6 and IL-8 in response to A. actinomycetemcomitans LPS stimulation compared to fibroblasts and epithelial cells individually. The 3D co-culture model was stimulated with noncytotoxic concentrations of: i) hBD-3 (10 and 20 µM) and LL -37 (0.1 and 0.2 µM), ii ) EGCG (1 and 5 µg/ml) and LL -37 (0.1 and 0.2 µM), iii) AC- PACs (25 and 50 µg/ml) and LL-37 (0.1 and 0.2 µM) alone and in association in the presence of A. actinomycetemcomitans LPS. A multiplex ELISA assay was used to quantify the secretion of 41 different cytokines, chemokines, growth factors and 13 different MMPs and TIMPs. Ours results showed that: i) the secretion and gene expression of hBD-1 and hBD-2 was up-regulated in a dose-dependent manner by green tea extract and EGCG. Green tea extract and EGCG were also able to prevent the degradation of recombinant hBD-1 and hBD-2 by a culture supernatant of P. gingivalis, ii) hBD-3 in association with LL-37 showed a synergistic effect to reduce the secretion of GRO- α, G-CSF, IP- 10, IL -6 and MCP -1, however had only additive effect on reducing the secretion of IL-8 in response to A. actinomycetemcomitans LPS stimulation, iii) the association of the peptide LL- 37 with EGCG and with AC- PACs showed a synergistic effect to reduce the secretion of GRO-α, G-CSF and IL-6 in response to A. actinomycetemcomitans LPS stimulation. Considering that the antimicrobial peptides hBD-3 and LL-37, as well as green tea extract, EGCG and AC- PACs, demonstrated the ability to regulate the secretion of inflammatory cytokines, up regulated the secretion of defensins by the cells and even to protect the defensins degradation by P. gingivalis, emerged as promising alternative adjunct therapy to conventional periodontal treatment. However future clinical studies are necessary to evaluate the role of peptides and natural compounds in the oral cavity and periodontal tissues

Fibrinogen-induced streptococcus mutans biofilm formation and adherence to endothelial cells.

Streptococcus mutans, the predominant bacterial species associated with dental caries, can enter the bloodstream and cause infective endocarditis. The aim of this study was to investigate S. mutans biofilm formation and adherence to endothelial cells induced by human fibrinogen. The putative mechanism by which biofilm formation is induced as well as the impact of fibrinogen on S. mutans resistance to penicillin was also evaluated. Bovine plasma dose dependently induced biofilm formation by S. mutans. Of the various plasma proteins tested, only fibrinogen promoted the formation of biofilm in a dose-dependent manner. Scanning electron microscopy observations revealed the presence of complex aggregates of bacterial cells firmly attached to the polystyrene support. S. mutans in biofilms induced by the presence of fibrinogen was markedly resistant to the bactericidal effect of penicillin. Fibrinogen also significantly increased the adherence of S. mutans to endothelial cells. Neither S. mutans cells nor culture supernatants converted fibrinogen into fibrin. However, fibrinogen is specifically bound to the cell surface of S. mutans and may act as a bridging molecule to mediate biofilm formation. In conclusion, our study identified a new mechanism promoting S. mutans biofilm formation and adherence to endothelial cells which may contribute to infective endocarditis.

Incisive canal deflation for correct implant placement: case report.

AIM: This article is a case report of a patient in whom the prosthetic planning indicated the necessity of an incisive canal deflation for the correct installation of an implant that is to be osseointegrated. CASE REPORT: In the reopening phase after the bone graft installation, the incisive canal deflation (biopsy of its content) was done and titanium implants were installed with one of them invading the anatomical space occupied previously by the incisive canal. The biopsy analysis showed fragments of the incisive artery and nerve, which are responsible for the anterior upper-tooth pulp, the periodontium vascularization and the innervation. From the anastomosis present along with other structures allied with the absence of teeth in the region, there was no detriment to the patient caused by the deflation. CONCLUSION: Incisive canal deflation is a viable technique in implantology. It can permit ideal prosthetic planning with no detriment to the patient.