Suppression of gingival inflammation induced by Porphyromonas gingivalis in rats by leupeptin

Leupeptin maintains redox homeostasis via targeting ROS-autophagy-inflammatory axis in LPS-stimulated macrophages and cytokines dichotomy in Con-A challenged lymphocyte

Information regarding cellular anti-inflammatory and immunomodulatory attributes of leupeptin with respect to modulation of perturbed macrophage function and lymphocytes has not yet been delineated, particularly in the context of ROS-cytokines-autophagy-inflammatory signalling cascades. Therefore, the present study identified the attributes and mechanisms of leupeptin, from actinomycetes, in relation to excessive oxidative stress mediated disrupted immune homeostasis and inflammatory mechanism in activated macrophages and lymphocytes. Results revealed that leupeptin treatment showed noticeable inhibition in the production of NO, ROS, mitochondrial membrane potential and phagocytosis activity in LPS-stimulated macrophages. These findings were accompanied by reduction in TNF-α, IL-1β, IL-6, IFN-γ/IL-10 ratio, endopeptidases, oxidative effectors (Cox-2, IL-5, IL-15, IL-17, COX-2), iNOS with concomitant increase in Arg 1, Msr 1 and Mrc - 1exprssion in leupeptin treatment. Additionally, compared to LPS-challenged cells, marked alleviation in MDC, lysotracker staining, beclin-1, LC3B expression, and enhanced p62 levels in leupeptin exposed cells indicate the reversal of impaired autophagy flux. Subsequently, oxi-inflammatory signalling analysis demonstrated p-PTEN, p-NF-κB, p-PI3K, p-Akt, p-p38, and ERK1/2 upregulation decisively thwarted by leupeptin administration. In silico analysis further implied its target selectivity to these cascades. Furthermore, decreased proliferation index and Th1, Th2/IL-10 cytokines ratio in mitogen-challenged splenic lymphocytes confers its role in mitigating unwarranted inflammation mediated by disrupted regulation of adaptive immune cells. Together, these findings signify the attributes of leupeptin as an alternative anti-inflammatory strategy and affirm it as a promising natural entity to modulate immune-mediated response during inflammatory disorder.

Resveratrol attenuates the pathogenic and inflammatory properties of Porphyromonas gingivalis

Porphyromonas gingivalis has been strongly associated with chronic periodontitis, which affects tooth-supporting tissues. This Gram-negative anaerobic bacterium produces a repertoire of virulence factors that modulate tissue destruction directly or indirectly by the induction of inflammatory processes. The aim of this study was to investigate the effects of resveratrol, a major polyphenol found in grapes and wine, on the growth and virulence properties of P. gingivalis as well as on gingival keratinocyte tight junction integrity and the host inflammatory response. Resveratrol exhibited antibacterial activity that may result from damage to the bacterial cell membrane. Resveratrol also killed a pre-formed P. gingivalis biofilm and reduced bacterial adherence to matrix proteins. In addition, resveratrol had a protective effect on the integrity of the keratinocyte tight junctions by inhibiting its breakdown by P. gingivalis. This may be related to the ability of resveratrol to inhibit the protease activities of P. gingivalis. Lastly, resveratrol reduced P. gingivalis-mediated activation of the NF-κB signaling pathway and attenuated TREM-1 gene expression as well as soluble TREM-1 secretion in monocytes. The effect on NF-κB activation likely results from the ability of resveratrol to act as a PPAR-γ agonist. In summary, the antibacterial, anti-adherence, and antiprotease properties of resveratrol, as well as its ability to protect the gingival keratinocyte barrier and attenuate the inflammatory response in monocytes suggest that it may be a promising novel therapeutic agent for treating periodontal disease.

Inhibitory activities of selected Sudanese medicinal plants on Porphyromonas gingivalis and matrix metalloproteinase-9 and isolation of bioactive compounds from Combretum hartmannianum (Schweinf) bark

Background

Periodontal diseases are one of the major health problems and among the most important preventable global infectious diseases. Porphyromonas gingivalis is an anaerobic Gram-negative bacterium which has been strongly implicated in the etiology of periodontitis. Additionally, matrix metalloproteinases-9 (MMP-9) is an important factor contributing to periodontal tissue destruction by a variety of mechanisms. The purpose of this study was to evaluate the selected Sudanese medicinal plants against P. gingivalis bacteria and their inhibitory activities on MMP-9.

Methods

Sixty two methanolic and 50% ethanolic extracts from 24 plants species were tested for antibacterial activity against P. gingivalis using microplate dilution assay method to determine the minimum inhibitory concentration (MIC). The inhibitory activity of seven methanol extracts selected from the 62 extracts against MMP-9 was determined by Colorimetric Drug Discovery Kit. In search of bioactive lead compounds, Combretum hartmannianum bark which was found to be within the most active plant extracts was subjected to various chromatographic (medium pressure liquid chromatography, column chromatography on a Sephadex LH-20, preparative high performance liquid chromatography) and spectroscopic methods (liquid chromatography-mass spectrometry, Nuclear Magnetic Resonance (NMR)) to isolate and characterize flavogalonic acid dilactone and terchebulin as bioactive compounds.

Results

About 80% of the crude extracts provided a MIC value ≤4 mg/ml against bacteria. The extracts which revealed the highest potency were: methanolic extracts of Terminalia laxiflora (wood; MIC = 0.25 mg/ml) followed by Acacia totrtilis (bark), Ambrosia maritima (aerial part), Argemone mexicana (seed), C. hartmannianum (bark), Terminalia brownii (wood) and 50% ethanolic extract of T. brownii (bark) with MIC values of 0.5 mg/ml. T. laxiflora (wood) and C. hartmannianum (bark) which belong to combretaceae family showed an inhibitory activity over 50% at the concentration of 10 μg/ml against MMP-9. Additionally, MMP-9 was significantly inhibited by terchebulin with IC₅₀ value of 6.7 μM.

Conclusions

To the best of our knowledge, flavogalonic acid dilactone and terchebulin were isolated from C. hartmannianium bark for the first time in this study. Because of terchebulin and some crude extracts acting on P. gingivalis bacteria and MMP-9 enzyme that would make them promising natural preference for preventing and treating periodontal diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1735-y) contains supplementary material, which is available to authorized users.

Dual Action of Myricetin on Porphyromonas gingivalis and the Inflammatory Response of Host Cells: A Promising Therapeutic Molecule for Periodontal Diseases

Periodontitis that affects the underlying structures of the periodontium, including the alveolar bone, is a multifactorial disease, whose etiology involves interactions between specific bacterial species of the subgingival biofilm and the host immune components. In the present study, we investigated the effects of myricetin, a flavonol largely distributed in fruits and vegetables, on growth and virulence properties of Porphyromonas gingivalis as well as on the P. gingivalis-induced inflammatory response in host cells. Minimal inhibitory concentration values of myricetin against P. gingivalis were in the range of 62.5 to 125 μg/ml. The iron-chelating activity of myricetin may contribute to the antibacterial activity of this flavonol. Myricetin was found to attenuate the virulence of P. gingivalis by reducing the expression of genes coding for important virulence factors, including proteinases (rgpA, rgpB, and kgp) and adhesins (fimA, hagA, and hagB). Myricetin dose-dependently prevented NF-κB activation in a monocyte model. Moreover, it inhibited the secretion of IL-6, IL-8 and MMP-3 by P. gingivalis-stimulated gingival fibroblasts. In conclusion, our study brought clear evidence that the flavonol myricetin exhibits a dual action on the periodontopathogenic bacterium P. gingivalis and the inflammatory response of host cells. Therefore, myricetin holds promise as a therapeutic agent for the treatment/prevention of periodontitis.

Tryptase and protease-activated receptor-2 stimulate scratching behavior in a murine model of ovalbumin-induced atopic-like dermatitis

The aim of the current study was to investigate the involvement of tryptase and protease-activated receptor-2 (PAR2) in the pathogenesis of itch using a recently developed murine model of atopic dermatitis (AD) elicited by epicutaneous sensitization with ovalbumin (OVA). We also examined whether tacrolimus exerts an antipruritic effect. Epicutaneous sensitization of BALB/c mice with OVA led to a significant increase in the number of scratches. Notably, PAR2 mRNA and protein levels as well as cutaneous levels of tryptase were significantly enhanced in epicutaneously sensitized mice. Pretreatment with the protease inhibitor, leupeptin, PAR2 antibody, and tacrolimus significantly reduced the number of degranulated mast cells and tryptase content, and consequently alleviated scratching behavior. Cetirizine (10mg/kg) exerted a significant inhibitory effect on the scratching behavior of mice, but did not affect the number of degranulated mast cells and induction of tryptase. Our results collectively suggest that tryptase and PAR2 are involved in OVA allergy-induced scratching behavior.

Inhibitory effects of sword bean extract on alveolar bone resorption induced in rats by Porphyromonas gingivalis infection

BACKGROUND

The domesticated legume, Canavalia gladiata (commonly called the sword bean), is known to contain canavanine. The fruit is used in Chinese and Japanese herbal medicine for treating the discharge of pus, but its pharmacological mechanisms are still unclear.

OBJECTIVES

This study examined the effect of sword bean extract (SBE) on (i) oral bacteria and human oral epithelial cells in vitro, and (ii) the initiation and progression of experimental Porphyromonas gingivalis-induced alveolar bone resorption in rats.

MATERIAL AND METHODS

A high-performance liquid chromatography/ultraviolet method was applied to quantitate canavanine in SBE. By assessing oral bacterial growth, we estimated the minimum inhibitory concentration and minimum bactericidal concentration of SBE, canavanine, chlorhexidine gluconate (CHX) solution. The cytotoxicity of SBE, canavanine, CHX, leupeptin and cystatin for KB cells was determined using a trypan blue assay. The effects of SBE, canavanine, leupeptin and cystatin on Arg-gingipain (Rgp) and Lys-gingipain (Kgp) were evaluated by colorimetric assay using synthetic substrates. To examine its effects on P. gingivalis-associated periodontal tissue breakdown, SBE was orally administered to P. gingivalis-infected rats.

RESULT

Sword bean extract contained 6.4% canavanine. SBE and canavanine inhibited the growth of P. gingivalis and Fusobacterium nucleatum. The cytotoxicity of SBE, canavanine and cystatin on KB cells was significantly lower than that of CHX. Inhibition of Rgp with SBE was comparable to that with leupeptin, a known Rgp inhibitor, and inhibition of Kgp with SBE was significantly higher than that with leupeptin at 500 μg/mL ( p < 0.05). P. gingivalis-induced alveolar bone resorption was significantly suppressed by administration of SBE, with bone levels remaining comparable to non-infected animals ( p < 0.05).

CONCLUSION

The present study suggests that SBE might be effective against P. gingivalis-associated alveolar bone resorption.

Inhibition of host- and bacteria-derived proteinases by natural anthocyanins

BACKGROUND AND OBJECTIVES

Host- and bacteria-derived proteinases are considered to play critical roles in periodontitis progression. This study investigated the ability of a blackcurrant extract and its major anthocyanins (cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside and delphinidin-3-O-rutinoside) to inhibit the activity of matrix metalloproteinases (MMPs), neutrophil elastase and periodontopathogen (Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola) proteinases.

MATERIAL AND METHODS

Enzyme inhibition was detected using fluorometric and colorimetric assays after incubating blackcurrant extract and its major anthocyanins (at concentrations of 6.25, 12.5, 25 and 50 μg/mL) with MMPs, elastase or bacterial proteinases, along with their specific substrates. Substrate degradation was recorded every hour for up to 4 h.

RESULTS

The blackcurrant extract (50 μg/mL) inhibited all proteinases tested. MMP-1 and MMP-9 were significantly inhibited by pure anthocyanins at concentrations ranging from 6.25 to 50 μg/mL. Elastase activity was inhibited by cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside in the range of 6.25-50 μg/mL and by delphinidin-3-O-rutinoside at 50 μg/mL. P. gingivalis, T. forsythia and T. denticola proteinases were also significantly inhibited by pure anthocyanins. In all cases, enzyme inhibition was time-dependent.

CONCLUSION

Our study showed that a blackcurrant extract and its major anthocyanins were able to inhibit the activity of host- and bacteria-derived proteinases. This suggests that such natural compounds may represent promising agents for use in adjunctive treatments for periodontitis.

Inhibitory effect of cranberry polyphenol on biofilm formation and cysteine proteases of Porphyromonas gingivalis

BACKGROUND AND OBJECTIVE

The purpose of this study was to investigate the effects of cranberry polyphenol fraction on biofilm formation and activities of Arg-gingipain and Lys-gingipain in Porphyromonas gingivalis.

MATERIAL AND METHODS

The polyphenol fraction was prepared by using a glass column packed with Amberlite XAD 7HP and 70% aqueous ethanol as an elution solvent.

RESULTS

Synergistic biofilm formation by P. gingivalis and Fusobacterium nucleatum was significantly inhibited by the polyphenol fraction at a concentration of 250 microg/mL compared with untreated controls (p < 0.01). Arg-gingipain and Lys-gingipain activities in P. gingivalis ATCC 33277 and FDC 381 were inhibited significantly at a polyphenol fraction concentration of > or = 1 microg/mL (p < 0.05).

CONCLUSION

These findings indicate that the polyphenol fraction inhibits biofilm formation and the Arg-gingipain and Lys-gingipain activities of P. gingivalis.

Inhibitory effect of green tea catechins on cysteine proteinases in Porphyromonas gingivalis

The purpose of this study was to examine the effects of catechins and their derivatives on the activities of Arg-gingipain (Rgp) and Lys-gingipain (Kgp) in Porphyromonas gingivalis. Catechin derivatives, which included (-)-epigallocatechin gallate, (-)-epicatechin gallate, (-)-gallocatechin gallate, and (-)-catechin gallate, significantly inhibited the Rgp activity. The 50% inhibitory concentrations (IC50s) of these catechin derivatives for Rgp ranged from 3 to 5 microm. While (-)-epigallocatechin and (-)-gallocatechin moderately inhibited Rgp activity (IC50s, 20 microm), (-) -epicatechin, (+)-catechin, and gallic acid were not effective, with IC50s greater than 300 microm. Further, some of the catechin derivatives tested also inhibited the Kgp activity, though to a lesser extent than inhibition of the Rgp activity. These findings suggest that green tea catechins may have the potential to reduce periodontal breakdown resulting from the potent proteinase activity of P. gingivalis.

Isolation and characterization of a novel and potent inhibitor of Arg-gingipain from Streptomyces sp. strain FA-70

Arg-gingipain (Rgp) is a major cysteine proteinase produced by the oral bacterium Porphyromonas gingivalis, which is a major pathogen of advanced periodontal diseases. This enzyme is important for the bacterium both to exhibit its virulence and to survive in periodontal pockets. The development of Rgp inhibitors thus provides new therapeutic approaches to periodontal diseases. In this study, we first isolated and purified a novel and potent inhibitor of Rgp from the culture supernatant of Streptomyces species strain FA-70, now designated as FA-70C1. This compound was found to be an antipain analog composed of phenylalanyl-ureido-citrullinyl-valinyl-cycloarginal (C27H43N9O7). The Ki value was calculated to be 4.5x10(-9) M when benzyloxycarbonyl-phenylalanyl-arginine-4-methly-coumaryl-7-amide was used as a substrate. This compound also inhibited cathepsins B, L, and H, though their Ki values were much higher than that of Rgp. FA-70C1 had little or no inhibitory activity on Lys-gingipain, another cysteine proteinase of P. gingivalis. The Rgp-induced degradation of various human proteins was completely blocked by this inhibitor. Disruption of both the bactericidal activity of polymorphonuclear leukocytes and the viability of human fibroblasts and umbilical vein endothelial cells induced by the culture supernatant of P. gingivalis was suppressed by the inhibitor in a dose-dependent manner. The enhancement of vascular permeability induced by in vivo administration of the culture supernatant of P. gingivalis was strongly inhibited by the inhibitor. Furthermore, the growth of P. gingivalis was suppressed by FA-70C1 in a dose-dependent manner. These results strongly suggest that FA-70C1 is a useful tool to prevent the virulence of P. gingivalis.