Potential Value of a Rice Protein Extract, Containing Proteinaceous Inhibitors against Cysteine Proteinases from Porphyromonas gingivalis , for Managing Periodontal Diseases

Implications of Porphyromonas gingivalis peptidyl arginine deiminase and gingipain R in human health and diseases

Porphyromonas gingivalis is a major pathogenic bacterium involved in the pathogenesis of periodontitis. Citrullination has been reported as the underlying mechanism of the pathogenesis, which relies on the interplay between two virulence factors of the bacterium, namely gingipain R and the bacterial peptidyl arginine deiminase. Gingipain R cleaves host proteins to expose the C-terminal arginines for peptidyl arginine deiminase to citrullinate and generate citrullinated proteins. Apart from carrying out citrullination in the periodontium, the bacterium is found capable of citrullinating proteins present in the host synovial tissues, atherosclerotic plaques and neurons. Studies have suggested that both virulence factors are the key factors that trigger distal effects mediated by citrullination, leading to the development of some non-communicable diseases, such as rheumatoid arthritis, atherosclerosis, and Alzheimer’s disease. Thus, inhibition of these virulence factors not only can mitigate periodontitis, but also can provide new therapeutic solutions for systematic diseases involving bacterial citrullination. Herein, we described both these proteins in terms of their unique structural conformations and biological relevance to different human diseases. Moreover, investigations of inhibitory actions on the enzymes are also enumerated. New approaches for identifying inhibitors for peptidyl arginine deiminase through drug repurposing and virtual screening are also discussed.

Dental follicle cells derived small extracellular vesicles inhibit pathogenicity of Porphyromonas gingivalis

OBJECTIVE

It aims to explore the effect of dental follicle cells derived small extracellular vesicles (D-sEV) with or without lipopolysaccharides (LPS) pretreating on the pathogenicity of Porphyromonas gingivalis (P. gingivalis).

METHODS

The antibacterial effects of D-sEV were evaluated by measuring the growth, biofilm formation, gingipains and type IX secretion system (T9SS) expression of P. gingivalis. And the influence of D-sEV on P. gingivalis adhesion, invasion, cytotoxicity, and host immune response was examined in gingival epithelial cells (GECs). Then P. gingivalis treated with D-sEV was applied to investigate the pathogenicity in experimental periodontitis of mice.

RESULTS

It showed that both D-sEV and P. gingivalis LPS pretreated D-sEV (L-D-sEV) could target P. gingivalis, inhibit their growth and biofilm formation, and hinder the attachment and invasion in GECs, therefore remarkably decreasing P. gingivalis cytotoxicity and the expression of IL-1β and IL-6 in GECs. In addition, they significantly reduced the expression of P. gingivalis virulence factors (gingipains and T9SS). In vivo, it showed that the bacteria in the gingiva were significantly decreased after sEV treatment. Meanwhile, less bone loss and fewer inflammatory cells infiltration and osteoclast formation in D-sEV and L-D-sEV groups.

CONCLUSION

Both D-sEV and L-D-sEV were proven to inhibit the pathogenicity of P.gingivalis and thus prevented the development of periodontitis.

Influence of antibacterial effects of tetracycline, laser, and photodynamic therapy on cell viability, cell damage, and virulence of Porphyromonas gingivalis

INTRODUCTION

This study compares and evaluates the efficacy of tetracycline, laser and photodynamic therapy on bacterial counts, cell damage, cell viability and neutralization of gingipains.

MATERIAL AND METHODS

P.gingivalis (ATCC 33,277) was cultured anaerobically. The minimal inhibitory concentration (MIC) for 50% inhibition of P.gingivalis by tetracycline, laser, and toluidine blue (TB) was determined using spectrophotometry. The antibacterial effects, cell viability, cell damage and neutralization of gingipains of the treated groups was evaluated by microbial culture and counting, 2,3 Bis 2 Methyloxy-4 Nitro-5 Sulphophenyl 2 H tetrazolium-5-Carboxaanilide (MTT) assay, lactate dehydrogenase (LDH) assay, and gingipain assay (BAPNA).

RESULTS

The MIC of tetracycline, toulidine, diode laser (810nmm; 0.5 Watts) is 1 µg/mL, 50 µg/mL and 15 s respectively. Comparative analysis for bacterial colony reduction was highest in tetracycline followed by PDT and then laser group at p < 0.01. MTT assay shows a significantly lesser number of viable cells in the tetracycline and PDT group when compared to laser group p < 0.01. Comparative analysis for cell damage using LDH shows the highest results for PDT followed by tetracycline and laser at p < 0.01. The highest neutralization of the gingipains is seen in the PDT group followed by tetracycline and laser groups at p < 0.01.

CONCLUSION

PDT shows highest antibacterial activity, gingipain neutralization, cell damage, and least number of viable cells in comparison with tetracycline and laser.

Clinical significance of ragA, ragB, and PG0982 genes in Porphyromonas gingivalis isolates from periodontitis patients

Consistent detection of ragA, ragB, and PG0982 in the genome of Porphyromonas gingivalis (P. gingivalis) isolates from periodontitis patients suggests that genotypes containing these genes may influence virulence and P. gingivalis-associated periodontitis progression. This study evaluated the prevalence of these genes in P. gingivalis isolates from periodontitis patients (n = 28) and in isolates from periodontally healthy P. gingivalis carriers (n = 34). The association of these genes with progression of periodontitis, in vitro cell invasiveness, and bacterial survival following periodontal therapy was also assessed. Periodontal charting and microbiological sampling were done at baseline, and at 6, 12, and 24 months following subgingival debridement of the periodontitis patients. Healthy controls were assessed at baseline for comparison. P. gingivalis isolates were analysed by ragA, ragB, and PG0982 specific polymerase chain reaction (PCR) and Sanger sequencing. Primary human gingival fibroblasts were used for invasion experiments. Results showed that 25% of the tested isolates from the periodontitis group had ragB detected, whereas this gene was undetected in isolates from healthy participants. However, none of the selected genes was associated with an increased cell invasiveness in vitro, with bacterial survival, or with significant clinical periodontal parameter changes. Identification of genes that influence P.gingivalis virulence and therapeutic outcome may have a diagnostic or prognostic value.

Inhibition of gingipains and Porphyromonas gingivalis growth and biofilm formation by prenyl flavonoids

BACKGROUND AND OBJECTIVE

Porphyromonas gingivalis is considered a major pathogen of chronic periodontitis, which also may be implicated with systemic diseases such as atherosclerosis. Secreted cysteine proteases, gingipains Rgp and Kgp, are essential for P. gingivalis virulence. Some polyphenols and flavonoids are known to inhibit gingipain activity and interfere with biofilm formation by P. gingivalis. Many bioactive compounds have been isolated from Epimedium species, but availability of these compounds on gingipains and P. gingivalis is still unclear. Therefore, the aim of this study was to evaluate natural products from medical plants to develop a new therapeutic agent against periodontal disease.

MATERIAL AND METHODS

Prenylated flavonoids were isolated from Epimedium species plant using column chromatographies. The inhibitory effect of the prenylated flavonoids against protease activity of gingipains were examined using purified gingipains and fluorogenic substrates. Anti-P. gingivalis activity was evaluated to analyze planktonic growth and biofilm formation in brain heart infusion medium in the presence of the prenylated flavonoids.

RESULTS

We isolated 17 prenylated flavonoids (Limonianin, Epimedokoreanin B, etc.) from Epimedium species. We found that some prenylated flavonoids inhibited gingipain activity in a non-competitive manner with Ki values at μm order. The prenylated flavonoids also hindered growth and biofilm formation of P. gingivalis, in a manner independent of gingipain inhibition by the compounds.

CONCLUSION

The results indicated an inhibitory effect of the prenylated flavonoids against P. gingivalis and would provide useful information for future development of periodontitis treatment that suppresses gingipains, P. gingivalis growth and biofilm formation.

Strategies for the inhibition of gingipains for the potential treatment of periodontitis and associated systemic diseases

Gingipains are the major virulence factors of Porphyromonas gingivalis, the main periodontopathogen. It is expected that inhibition of gingipain activity in vivo could prevent or slow down the progression of adult periodontitis. To date, several classes of gingipain inhibitors have been recognized. These include gingipain N-terminal prodomains, synthetic compounds, inhibitors from natural sources, antibiotics, antiseptics, antibodies, and bacteria. Several synthetic compounds are potent gingipain inhibitors but inhibit a broad spectrum of host proteases and have undesirable side effects. Synthetic compounds with high specificity for gingipains have unknown toxicity effects, making natural inhibitors more promising as therapeutic gingipain blockers. Cranberry and rice extracts interfere with gingipain activity and prevent the growth and biofilm formation of periodontopathogens. Although the ideal gingipain inhibitor has yet to be discovered, gingipain inhibition represents a novel approach to treat and prevent periodontitis. Gingipain inhibitors may also help treat systemic disorders that are associated with periodontitis, including cardiovascular disease, rheumatoid arthritis, aspiration pneumonia, pre-term birth, and low birth weight.

New properties of wheat bran: anti-biofilm activity and interference with bacteria quorum-sensing systems

Some plant extracts, have been demonstrated to interfere with the microbial metabolism of several pathogenic bacteria. Within this antimicrobial properties it has been described the potential to inhibit or destroy biofilms or to interfere in quorum-sensing (QS) systems. However, to our knowledge, no study exploring this potential of wheat-bran (WB) has been published. The purpose of the present study is to evaluate the anti-biofilm activity of WB against a cow mastitis strain of Staphylococcus aureus and also its possible interference with bacterial QS systems. The potential of inhibition and destruction of the biofilm was studied by different in vitro assays. Also, we tested the ability of WB to interfere in bacterial QS by degrading acyl-homoserine lactones (AHL) as one of the most studied QS signal molecules for Gram-negative bacteria. The soluble extract of WB at 0.5% showed anti-biofilm activity, inhibiting biofilm formation and also destroying it. Similarly, the > 300 kDa fraction from WB had significant anti-biofilm activity in both in vitro assays. The WB also showed a potential to interfere with bacterial QS systems, as it was demonstrated to contain certain lactonase activity able to reduce AHL concentration in the medium. The present study reveals two additional beneficial properties of WB extract never explored before, which may be related to the presence of defence compounds in the plant extract able to interfere with microbial biofilms and also QS systems.