Salivary microbiota reflecting changes in subgingival microbiota.

The purpose of this study was to determine whether subgingival microbial changes according to the severity of periodontal disease and following the non-surgical periodontal treatment of periodontitis are reflected in the saliva microbiota. Subgingival and saliva samples were collected from 7 periodontally healthy controls, 14 patients with gingivitis, 12 with moderate periodontitis, and 18 with severe periodontitis. Among subjects who received treatment, seven moderate and seven severe periodontitis patients were selected for post-treatment microbial analysis, and their samples were analyzed at baseline and 6 months after treatment. The V3 and V4 regions of the 16S rRNA gene were sequenced, and correlations of the relative abundance of phyla and health- or periodontitis-dominant species between subgingival plaque and saliva samples were analyzed using Spearman signed-rank tests. Alpha diversity was higher in saliva than subgingival plaque samples, and beta diversity was significantly different between the two samples. However, levels of phyla and most health- or periodontitis-dominant species in salivary microbiota were significantly correlated with those in subgingival plaque. The improvement in clinical parameters following treatment was accompanied by a microbial shift not only in subgingival plaque but also in saliva. The abundance of 2 phyla including Bacteroidetes, 6 genera including Porphyromonas and Treponema, and 11 species including Porphyromonas gingivalis, Tannerella forsythia, and Filifactor alocis was significantly reduced in saliva following treatment. These results indicate that the salivary microbiota can reflect changes in the subgingival microbiota, suggesting that saliva can be used as a diagnostic tool to monitor the periodontal health status of individuals. IMPORTANCE: The salivary microbiota has attracted increasing attention as a promising method for monitoring periodontal disease. With regard to the pathogenesis of periodontal disease, however, subgingival plaque microbiota is the dominant etiological factor. Although it has been established that periodontopathogenic bacteria exist in saliva and their distribution differs, depending on the severity of the disease, it is necessary to analyze the extent to which the salivary microbiota reflects the subgingival microbiota. This study explored whether subgingival microbial changes according to the severity of periodontal disease and following the non-surgical periodontal treatment of periodontitis are reflected in the saliva microbiota and concluded that the salivary microbiota can reflect changes in the subgingival microbiota. Saliva can be used as a diagnostic tool to monitor the periodontal health status of individuals.

Differences Between Vietnamese Living in Germany and German Periodontitis Patients in Periodontal Conditions and Subgingival Microbiota.

INTRODUCTION AND AIMS: A number of studies have reported ethnic differences in the prevalence and severity of periodontitis. Such discrepancies could be attributed to disparities in periodontal risk factors, as well as variations in the composition of the subgingival microbiota. Given the substantial Vietnamese population residing in the former German Democratic Republic, the present study aimed to compare the clinical and microbial characteristics of periodontitis patients of Vietnamese Asian origin living in Germany with those of German Caucasian periodontitis patients. METHODS: A total of 60 patients with a minimum stage II periodontitis diagnosis were included in the study. Of these, 30 were of Vietnamese origin, with an average age of 55 years and a male prevalence of 33.3%. The remaining 30 patients were of German origin, with an average age of 54.5 years and a male prevalence of 40%. The periodontal diagnosis was made in accordance with the recently revised classification of periodontal disease. The pooled subgingival plaque samples were subjected to next-generation sequencing on the MiSeq platform (Illumina). RESULTS: The German patients were significantly more likely to be smokers (56.7% vs 13.3%), had significantly higher body mass index (26 vs 22.6 kg/m²), probing depth (4.1 vs 3.6 mm), and clinical attachment loss (5 vs 4.1 mm). In terms of microbiota, the Vietnamese patients exhibited significantly lower beta diversity compared to the German patients, and smokers demonstrated a significantly higher beta diversity compared to nonsmokers. The microbiota of both groups differed most significantly in the relative abundance of Porphyromonas gingivalis (Vietnamese) and Fusobacteriia (German). CONCLUSIONS: German patients with periodontitis showed more severe periodontal symptoms and more pronounced periodontal risk factors compared to Vietnamese patients. Both patient groups also showed significant differences in the subgingival microbiota. CLINICAL RELEVANCE: Compared to Vietnamese living in Germany, German patients have a higher need for periodontal treatment and at the same time the risk factors of smoking and obesity should be reduced. More research is needed before the differences in oral microbiota between the two groups can lead to individualised therapeutic approaches.

SIRT6 alleviates senescence induced by Porphyromonas gingivalis in human gingival fibroblasts.

OBJECTIVE: Bidirectional influences between senescence and inflammation are newly discovered. This study aimed to clarify the roles and mechanism of Porphyromonas gingivalis (P. gingivalis) in exacerbating senescence in human gingival fibroblasts (HGFs). DESIGN: Subgingival plaque and gingivae were collected from twenty-four periodontitis patients and eighteen periodontally healthy subjects. Quantities of P. gingivalis in subgingival plaque were explored using real-time PCR and the expressions of p53, p21 and SIRT6 in gingivae were detected by IHC. Moreover, senescence in HGFs was induced by P. gingivalis lipopolysaccharide (LPS) and the expressions of senescence-related ß-galactosidase (SA-ß-gal), p53, p21 and senescence-associated secretory phenotype (IL-6 and IL-8) with or without treatment by SIRT6 activator UBCS039 were explored by IHC, western blot and ELISA, respectively. In addition, the levels of SIRT6, Nrf2, HO-1 and reactive oxygen species (ROS) were examined by western blot and flow cytometry. RESULTS: Quantities of P. gingivalis in subgingival plaque and semi-quantitative scores of p53 and p21 in gingivae of periodontitis patients were increased compared with healthy controls (p < 0.05), while SIRT6 score in periodontitis patients was decreased (p < 0.001). Quantities of P. gingivalis were positively correlated with p53 and p21 scores (0.6 < r < 0.9, p < 0.01), and negatively correlated with SIRT6 score (-0.9 < r<-0.6, p < 0.01). Moreover, P. gingivalis LPS increased the levels of SA-ß-gal, p53, p21, IL-6, IL-8 and ROS and decreased the levels of SIRT6, Nrf2 and HO-1 in HGFs, which was rescued by UBCS039 (p < 0.05). CONCLUSIONS: P. gingivalis LPS could induce senescence of HGFs, which could be reversed by SIRT6 via Nrf2-HO-1 signaling pathway.

Antibacterial Activity of Cissus quadrangularis (Veldt Grape) Against Porphyromonas gingivalis, a Keystone Pathogen in Periodontal Disease: An In Vitro Study.

BACKGROUND: Porphyromonas gingivalis, a keystone pathogen and one of the primary pathogens responsible for periodontitis, leads to a chronic inflammatory condition that destroys the periodontal tissues and ultimately results in tooth loss. While conventional non-surgical therapy combined with antibiotics and local drug delivery systems are commonly used to treat periodontitis, certain medicinal herbs have also demonstrated efficacy in its prevention. Cissus quadrangularis L. (CQ), a perennial plant from the Vitaceae family, is widely recognized and used as a medicinal herb in many tropical countries, predominantly in India, Sri Lanka, Thailand, Java, West Africa, and the Philippines. AIM: The aim of the study was to determine the antibacterial activity of CQ against the periodontal keystone pathogen P. gingivalis. METHOD: Aqueous and ethanolic extracts of CQ were prepared using a Soxhlet extractor. The antibacterial effectiveness of these extracts against the periodontal pathogen P. gingivalis was evaluated at different concentrations, and the minimal inhibitory concentration (MIC) was determined using broth microdilution. RESULTS: The ethanolic extract of CQ mixed with 10% dimethyl sulfoxide (DMSO) showed higher inhibition compared to the aqueous extract of CQ against P. gingivalis. CONCLUSION: Our study revealed the potent inhibitory effects of CQ against P. gingivalis. Both aqueous and ethanolic extracts displayed MIC values of 500 µg/mL. Notably, the ethanolic extract of CQ, dissolved in 10% DMSO, demonstrated superior efficacy with a lower IC50 value of 194.36 µg/mL. These findings indicate promising potential for CQ in the management of periodontal disease.

Antimicrobial adhesive self-healing hydrogels for efficient dental biofilm removal from periodontal tissue.

OBJECTIVES: Oral biofilms, including pathogens such as Porphyromonas gingivalis, are involved in the initiation and progression of various periodontal diseases. However, the treatment of these diseases is hindered by the limited efficacy of many antimicrobial materials in removing biofilms under the harsh conditions of the oral cavity. Our objective is to develop a gel-type antimicrobial agent with optimal physicochemical properties, strong tissue adhesion, prolonged antimicrobial activity, and biocompatibility to serve as an adjunctive treatment for periodontal diseases. METHODS: Phenylboronic acid-conjugated alginate (Alg-PBA) was synthesized using a carbodiimide coupling agent. Alg-PBA was then combined with tannic acid (TA) to create an Alg-PBA/TA hydrogel. The composition of the hydrogel was optimized to enhance its mechanical strength and tissue adhesiveness. Additionally, the hydrogel's self-healing ability, erosion and release profile, biocompatibility, and antimicrobial activity against P. gingivalis were thoroughly characterized. RESULTS: The Alg-PBA/TA hydrogels, with a final concentration of 5 wt% TA, exhibited both mechanical properties comparable to conventional Minocycline gel and strong tissue adhesiveness. In contrast, the Minocycline gel demonstrated negligible tissue adhesion. The Alg-PBA/TA hydrogel also retained its rheological properties under repeated 5 kPa stress owing to its self-healing capability, whereas the Minocycline gel showed irreversible changes in rheology after just one stress cycle. Additionally, Alg-PBA/TA hydrogels displayed a sustained erosion and TA release profile with minimal impact on the surrounding pH. Additionally, the hydrogels exhibited potent antimicrobial activity against P. gingivalis, effectively eliminating its biofilm without compromising the viability of MG-63 cells. SIGNIFICANCE: The Alg-PBA/TA hydrogel demonstrates an optimal combination of mechanical strength, self-healing ability, tissue adhesiveness, excellent biocompatibility, and sustained antimicrobial activity against P. gingivalis. These attributes make it superior to conventional Minocycline gel. Thus, the Alg-PBA/TA hydrogel is a promising antiseptic candidate for adjunctive treatment of various periodontal diseases.

Fatal Renal Abscess Caused by Porphyromonas gingivalis and Subcapsular Hemorrhage, Japan.

A 61-year-old man in Japan with abdominal pain was suspected of having a renal tumor. Despite initial treatment, his condition rapidly deteriorated, leading to death. Postmortem examination revealed a renal abscess and sepsis caused by Porphyromonas gingivalis. This case underscores the need to consider atypical pathogens in renal masses.

First crystal structure of the DUF2436 domain of virulence proteins from Porphyromonas gingivalis.

Porphyromonas gingivalis is a major pathogenic oral bacterium that is responsible for periodontal disease. It is linked to chronic periodontitis, gingivitis and aggressive periodontitis. P. gingivalis exerts its pathogenic effects through mechanisms such as immune evasion and tissue destruction, primarily by secreting various factors, including cysteine proteases such as gingipain K (Kgp), gingipain R (RgpA and RgpB) and PrtH (UniProtKB ID P46071). Virulence proteins comprise multiple domains, including the pro-peptide region, catalytic domain, K domain, R domain and DUF2436 domain. While there is a growing database of knowledge on virulence proteins and domains, there was no prior evidence or information regarding the structure and biological function of the well conserved DUF2436 domain. In this study, the DUF2436 domain of PrtH from P. gingivalis (PgDUF2436) was determined at 2.21 Šresolution, revealing a noncanonical ß-jelly-roll sandwich topology with two antiparallel ß-sheets and one short α-helix. Although the structure of PgDUF2436 was determined by the molecular-replacement method using an AlphaFold model structure as a template, there were significant differences in the positions of ß1 between the AlphaFold model and the experimentally determined PgDUF2436 structure. The Basic Local Alignment Search Tool sequence-similarity search program showed no sequentially similar proteins in the Protein Data Bank. However, DaliLite search results using structure-based alignment revealed that the PgDUF2436 structure has structural similarity Z-scores of 5.9-5.4 with the C-terminal domain of AlgF, the D4 domain of cytolysin, IglE and the extracellular domain structure of PepT2. This study has elucidated the structure of the DUF2436 domain for the first time and a comparative analysis with similar structures has been performed.

The antimicrobial peptide Microcin C7 inhibits the growth of Porphyromonas gingivalis and improves the perodontal status in a rat model.

AIMS: This study aimed to investigate the antibacterial and anti-inflammatory effects of the antimicrobial peptide Microcin C7 for Porphyromonas gingivalis-associated diseases. METHODS AND RESULTS: Reverse-phase high-performance liquid chromatography revealed that Microcin C7 could remain 25.5% at 12 hours in saliva. At a concentration of <10 mg mL-1, Microcin C7 showed better cytocompatibility, as revealed by hemolysis test and subchronic systemic toxicity test. Moreover, the minimum inhibitory concentration and minimum bactericidal concentration of Microcin C7 were analyzed using a broth microdilution method, bacterial growth curve, scanning electron microscopy, and confocal laser microscopy and determined to be 0.16 mg mL-1 and 5 mg mL-1, respectively. Finally, in a rat model, 5 mg mL-1 Microcin C7 showed better performance in decreasing the expression of inflammatory factors (IL-1ß, IL-6, IL-8, and TNF-α) and alveolar bone resorption than other concentrations. CONCLUSIONS: Microcin C7 demonstrated favorable biocompatibility, antibacterial activity, anti-inflammatory effect, and could decrease the alveolar bone resorption in a rat model, indicating the promising potential for clincal translation and application on P. gingivalis-associated diseases.

Optimization and evaluation of a chitosan-coated PLGA nanocarrier for mucosal delivery of Porphyromonas gingivalis antigens.

Recent advances in understanding Alzheimer's disease (AD) suggest the possibility of an infectious etiology, with Porphyromonas gingivalis emerging as a prime suspect in contributing to AD. P. gingivalis may invade systemic circulation via weakened oral/intestinal barriers and then cross the blood-brain barrier (BBB), reaching the brain and precipitating AD pathology. Based on the proposed links between P. gingivalis and AD, a prospective approach is the development of an oral nanovaccine containing P. gingivalis antigens for mucosal delivery. Targeting the gut-associated lymphoid tissue (GALT), the nanovaccine may elicit both mucosal and systemic immunity, thereby hampering P. gingivalis ability to breach the oral/intestinal barriers and the BBB, respectively. The present study describes the optimization, characterization, and in vitro evaluation of a candidate chitosan-coated poly(lactic-co-glycolic acid) (PLGA-CS) nanovaccine containing a P. gingivalis antigen extract. The nanocarrier was prepared using the double emulsion solvent evaporation method and optimized for selected experimental factors, e.g. PLGA amount, surfactant concentration, w1/o phase ratio, applying a d-optimal statistical design to target the desired physicochemical criteria for its intended application. After nanocarrier optimization, the nanovaccine was characterized in terms of particle size, polydispersity index (PdI), ζ-potential, encapsulation efficiency (EE), drug loading (DL), morphology, and in vitro release profile, as well as for mucoadhesivity, stability under simulated gastrointestinal conditions, antigen integrity, in vitro cytotoxicity and uptake using THP-1 macrophages. The candidate PLGA-CS nanovaccine demonstrated appropriate physicochemical, mucoadhesive, and antigen release properties for oral delivery, along with acceptable levels of EE (55.3 ± 3.5 %) and DL (1.84 ± 0.12 %). The integrity of the encapsulated antigens remained uncompromised throughout NPs production and simulated gastrointestinal exposure, as confirmed by SDS-PAGE and Western blotting analyses. Furthermore, the nanovaccine showed effective in vitro uptake, while exhibiting low cytotoxicity. Taken together, these findings underscore the potential of PLGA-CS NPs as carriers for adequate antigen mucosal delivery, paving the way for further investigations into their applicability as vaccine candidates against P. gingivalis.

Analysis of vaginal flora diversity and study on the role of Porphyromonas asaccharolytica in promoting IL-1ß in regulating cervical cancer.

Cervical cancer, a prevalent malignancy in the female reproductive tract, exhibits a high incidence. Existing evidence indicates a robust correlation between alterations in vaginal flora composition and the progression of cervical cancer. Nevertheless, there is a lack of clarity concerning the specific microorganisms within the vaginal microbiota that are linked to the onset and development of cervical cancer, as well as the mechanisms through which they exert carcinogenic effects. The 16 S ribosomal (rRNA) and metagenomic sequencing technology were used to analyze vaginal microorganisms, and screening for human papillomavirus (HPV) positive cervical cancer-associated microbial markers using fold change in mean bacterial abundance. Moreover, vaginal microenvironmental factors were detected, and the local vaginal inflammatory state in patients with cervical cancer was subjected to assay via qRT-PCR and ELISA. The hub inflammatory genes were screened by transcriptome sequencing after co-culture of bacteria and normal cervical epithelial cells, and an in vitro model was utilized to assess the impacts of inflammatory factors on cervical cancer. Both cervical cancer patients and HPV-positive patients showed significant changes in the composition of the vaginal flora, characterised by a decrease in the abundance of Lactobacillus and an increase in the abundance of a variety of anaerobic bacteria; The microbial sequencing identified Porphyromonas, Porphyromonas_asaccharolytica, and Porphyromonas_uenonis as microbial markers for HPV-associated cervical cancer. Vaginal inflammatory factors in patients with cervical cancer were overexpressed. After Porphyromonas_asaccharolytica intervention on cervical epithelial H8 cells, interleukin (IL)-1ß, a hub differential gene, markedly promoted tumor-associated biological behaviors at the in vitro cytological level in cervical cancer. This study for the first demonstrated that Porphyromonas, Porphyromonas_asaccharolytica, and Porphyromonas_uenonis could serve as novel microbial markers for cervical cancer. Moreover, Porphyromonas_asaccharolytica was identified as having the ability to induce the overexpression of inflammatory genes in cervical epithelial cells to create a favorable microenvironment for the onset and development of cervical cancer. The effects of dysbacteriosis on cervical cancer were microbiologically elucidated.

A Novel Porphyromonas gingivalis Infection-Related Inflammatory Response-Related Genes Signature Predicts the Prognosis of Esophageal Squamous Cell Carcinoma.

Background: Our previous research showed that Porphyromonas gingivalis (P. gingivalis) infection can activate the inflammatory signaling pathway and promotes the malignancy development of esophageal squamous cell carcinoma (ESCC). However, the prognostic significance of inflammatory response-related genes (IRRGs) in P. gingivalis-infected ESCC requires further elucidation. Hence, our study constructed a prognostic signature based on P. gingivalis and IRRGs to forecast the survival of patients with ESCC, which may provide insight into new treatment options for ESCC patients. Methods: Differentially expressed genes (DEGs) were identified in P.gingivalis-infected and P.gingivalis-uninfected ESCC cell by RNA sequencing. A risk model was constructed and validated using the The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database by using univariate Cox regression analysis, LASSO, and the multivariate Cox regression analysis. Kaplan-Meier analysis was carried out to compare the overall survival (OS) between high-risk and low-risk groups. Single-sample gene set enrichment analysis was used to analyze the immune cell infiltration. The Genomics of Drug Sensitivity in Cancer database was used to predict drug sensitivity. Results: There were 365 DEGs between the P.gingivalis-infected and P.gingivalis-uninfected groups. Four genes including DKK1, ESRRB, EREG, and RELN were identified to construct the prognostic risk model (P = .012, C-index = 0.73). In both the training and validation sets, patients had a considerably shorter OS in the high-risk group than those in the low-risk group (P < .05). A nomogram was established using the risk score, gender, and N stage which could effectively forecast the prognosis of patients (P = .016, C-index = 0.66). The high-risk group displayed lower immune infiltrating cells, such as activated dendritic cells, type 2 T helper cells, and neutrophils (P < .05). A total of 41 drugs, including dactinomycin, luminespib, and sepantronium bromide, had a significant difference in IC50 between the 2 subgroups. Conclusion: We demonstrated the potential of a novel signature constructed from 4 P. gingivalis-related IRRGs for prognostic prediction in ESCC patients.

Alantolactone improves cognitive impairment in rats with Porphyromonas gingivalis infection by inhibiting neuroinflammation, oxidative stress, and reducing Aß levels.

Neuroinflammation caused by the chronic periodontal pathogen Porphyromonas gingivalis is growing regarded as as a key factor in the pathogenesis of Alzheimer's disease (AD). Alantolactone (AL), a sesquiterpene lactone isolated from the root of Inula racemosa Hook. f, has been proven to provide various neuroprotective effects. However, whether AL can improve cognitive impairment caused by P. gingivalis infection remains unclear. In this research, a rat model of P. gingivalis infection was used to examine the neuroprotective benefits of AL. The results revealed that 6 weeks of AL treatment (50 and 100 mg/kg) shortened escape latency and increased the number of crossings over the platform location and time spent in the target quadrant of P. gingivalis-infected rats in the Morris water maze experiment. By activating the Nrf2/HO-1 pathway, AL suppressed malondialdehyde (MDA) levels and simultaneously increased the activity of total superoxide dismutase (T-SOD). Furthermore, AL lowered the presence of IL-6, IL-1ß, and TNFα in the hippocampal and cortical tissues of P. gingivalis-infected rats by inhibiting astrocyte and microglial activation and NF-κB phosphorylation. AL also significantly reduced Aß levels in the cortical and hippocampus tissues of rats infected with P. gingivalis. In conclusion, AL improved cognitive impairment in P. gingivalis-infected rats by inhibiting neuroinflammation, reducing Aß1-42 level, and exerting antioxidative stress effects.

Corrigendum: TLR2 activation by Porphyromonas gingivalis requires both PPAD activity and fimbriae.

[This corrects the article DOI: 10.3389/fimmu.2022.823685.].

Role of fimbriae variations in Porphyromonas gulae biofilm formation.

OBJECTIVES: Porphyromonas gulae is a major causative agent of periodontal disease in companion animals that possesses various virulence factors, including fimbriae, lipopolysaccharides, and proteases. P. gulae fimbriae are classified into three genotypes (A, B, and C) based on their nucleotide sequences. Type C fimbrial isolates have been reported to be more virulent than other fimA types, suggesting that different fimA types may aid in the regulation of periodontal pathogenesis. Detailed findings regarding the ability of P. gulae to form biofilms have yet to be reported. Here, we investigated the contributions of fimbrial genotypes in P. gulae biofilm formation. METHODS: P. gulae and P. gingivalis biofilms were generated on plates and analyzed using confocal laser microscopy. Additionally, the biofilms formed were assessed by staining with crystal violet. Furthermore, the physical strength of P. gulae biofilms was examined by ultrasonication. RESULTS: Biofilms formed by P. gulae type C were denser than those formed by types A and B. Moreover, the amount of biofilm formed by type C strains was significantly greater than that formed by type A and B strains, which was similar to the biofilms formed by P. gingivalis with type II fimbriae. Additionally, the physical strength of the type C biofilm was significantly greater than that of the other strains. CONCLUSIONS: These results suggest that FimA variation may coordinate for biofilm formation. This is the first report on the observation and characterization of P. gulae biofilm formation.

Antimicrobial effects of epigallocatechin-3-gallate, a catechin abundant in green tea, on periodontal disease-associated bacteria.

OBJECTIVE: Epigallocatechin-3-gallate (EGCG), a catechin abundant in green tea, exhibits antibacterial activity. In this study, the antimicrobial effects of EGCG on periodontal disease-associated bacteria (Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, Fusobacterium nucleatum, and Fusobacterium periodontium) were evaluated and compared with its effects on Streptococcus mutans, a caries-associated bacterium. RESULTS: Treatment with 2 mg/ml EGCG for 4 h killed all periodontal disease-associated bacteria, whereas it only reduced the viable count of S. mutans by about 40 %. Regarding growth, the periodontal disease-associated bacteria were more susceptible to EGCG than S. mutans, based on the growth inhibition ring test. As for metabolism, the 50 % inhibitory concentration (IC50) of EGCG for bacterial metabolic activity was lower for periodontal disease-associated bacteria (0.32-0.65 mg/ml) than for S. mutans (1.14 mg/ml). Furthermore, these IC50 values were negatively correlated with the growth inhibition ring (r = -0.73 to -0.86). EGCG induced bacterial aggregation at the following concentrations: P. gingivalis (>0.125 mg/ml), F. periodonticum (>0.5 mg/ml), F. nucleatum (>1 mg/ml), and P. nigrescens (>2 mg/ml). S. mutans aggregated at an EGCG concentration of > 1 mg/ml. CONCLUSION: EGCG may help to prevent periodontal disease by killing bacteria, inhibiting bacterial growth by suppressing bacterial metabolic activity, and removing bacteria through aggregation.

Invasion of human dental pulp fibroblasts by Porphyromonas gingivalis leads to autophagy via the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin signaling pathway.

OBJECTIVES: Porphyromonas gingivalis is a pathogenic bacterium that causes periodontitis and dental pulp infection. Autophagy is a potential mechanism involved in inflammatory disease. This study established an in vitro model of P. gingivalis intracellular infection in human dental pulp fibroblasts (HDPFs) to investigate the effects of live P. gingivalis on HDPFs. METHODS: Morphological and quantification techniques such as fluorescence microscopy, transmission electron microscopy (TEM), indirect immunofluorescence analysis, enzyme-linked immunosorbent assay (ELISA), real-time polymerase chain reaction (PCR), and western blotting were used in this study. RESULTS: After cell invasion, P. gingivalis is mainly localized in the cytoplasm and lysosomes. Additionally, P. gingivalis activates autophagy in HDPFs by upregulating the expression of autophagy-related gene Beclin-1, activate autophagy-related gene12 (ATG12), and microtubule-associated protein light chain 3 (LC3). Furthermore, the invasion of P. gingivalis leads to increased phosphorylation of PI3K, Akt, and mTOR with the addition of rapamycin, whereas the addition of wortmannin decreased phosphorylation. This invasion of P. gingivalis, also causes an inflammatory response, leading to the upregulation of IL-1ß, IL-6, and TNF-α. Rapamycin helps decrease levels of pro-inflammatory cytokines, but the addition of wortmannin increases them. These results show that the invasion of P. gingivalis can cause excessive inflammation and promote the autophagy of HDPFs, which is regulated by PI3K/Akt/mTOR. CONCLUSIONS: P. gingivalis escapes the immune system by inducing autophagy in the host cells, causing excessive inflammation. P. gingivalis regulates autophagy in HDPFs through the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin pathway.

Epimedium polysaccharides mitigates Porphyromonas gingivalis-exacerbated intestinal inflammation by suppressing the Th17 pathway and modulating the gut microbiota.

This study aimed to investigate the potential alleviating effect of Epimedium polysaccharide (EP) on intestinal inflammation aggravated by Porphyromonas gingivalis (Pg). P. gingivalis, an oral pathogen, may play a role in intestinal inflammation, highlighting the necessity to explore substances capable of inhibiting its pathogenicity. Initially, in vitro screening experiments utilizing co-culturing and quantitative polymerase chain reaction revealed that EP significantly inhibited the growth of P. gingivalis and the levels of virulence genes, including Kgp and RgpA. Subsequent mouse experiments demonstrated that EP notably ameliorated Pg-aggravated weight loss, disease activity index, histopathological lesions, and disruption of intestinal barrier integrity, evidenced by a reduction in tight junction protein levels. Flow cytometry analysis further illustrated that EP attenuated Pg-induced Th17 differentiation and Th17-related cytokines, such as IL-17 and IL-6. Additionally, 16S rRNA amplicon sequencing analysis elucidated that EP significantly mitigated Pg-induced gut microbiota dysbiosis, enriching potentially beneficial microbes, including Akkermansia and Bifidobacterium. The metabolomic analysis provided further insight, indicating that EP intervention altered the accumulation of relevant intestinal metabolites and exhibited correlations with disease indicators. In conclusion, our research suggested that EP holds promise as a prospective therapeutic agent for alleviating P. gingivalis-aggravated intestinal inflammation.

Frequency of Fimbrial Gene Types I, Ib, and II in Clinical Strains of Porphyromonas gingivalis Characterized From Periodontitis Patients.

Objective Porphyromonas gingivalis (P. gingivalis) is considered the predominant pathogen in association with different stages of periodontitis, and fim genes play a vital role in adherence and colonization. This study is thus aimed to detect the prevalence of P. gingivalis and the frequency of fim gene types among the clinical strains isolated from periodontitis patients. Methods Plaque samples (N = 45) were collected from patients with three different stages of periodontitis (n = 15 in each group). All the samples were inoculated onto sterile anaerobic blood agar and were processed anaerobically using a GasPak system at 37°C for five to seven days. Standard microbiological techniques were used to identify P. gingivalis. Genomic DNA was extracted, and polymerase chain reaction (PCR) was carried out to detect the frequency of three fim gene types, using specific primers. Results P. gingivalis was more prevalent in Group III (93.3%), followed by 26.7% in Group II, and 13.3% in Group I. Maximum isolates were seen in the age group of 40-50, with no significance within the genders. fim type I was frequent in Group III (78.5% (n = 11)), followed by 0.25% (n = 1) under Group II, with no other fim types in the other groups.  Conclusion Prevalence of P. gingivalis and frequency of fim genes, in association with its virulence, were observed. Periodical monitoring of such virulence genes would aid in the theranostic approach to combat the complications caused by P. gingivalis in periodontitis cases.

In Silico Docking of Medicinal Herbs Against P. gingivalis for Chronic Periodontitis Intervention.

OBJECTIVE: This study aimed to explore the therapeutic potential of medicinal herbs for chronic periodontitis by examining the molecular interactions between specific herbal compounds and the heme-binding protein of Porphyromonas gingivalis, a key pathogen involved in the disease. METHODS: The crystal structure of heme-binding protein was obtained from the Protein Data Bank. Herbal compounds were identified through an extensive literature review. Molecular docking simulations were performed to predict binding affinities, followed by Absorption, Distribution, Metabolism, and Excretion (ADME) parameter prediction. Drug-likeness was assessed based on Lipinski's Rule of Five, and pharmacophore modeling was conducted to identify key molecular interactions. RESULTS: The molecular docking simulations revealed that chelidonine, rotenone, and myricetin exhibited significant binding affinities to the heme-binding protein, with docking scores of -6.5 kcal/mol, -6.4 kcal/mol, and -6.1 kcal/mol, respectively. These compounds formed stable interactions with key amino acid residues within the binding pocket. ADME analysis indicated that all 3 compounds had favourable pharmacokinetic properties, with no violations of Lipinski's rules and minimal predicted toxicity. Pharmacophore modeling further elucidated the interaction profiles, highlighting specific hydrogen bonds and hydrophobic interactions critical for binding efficacy. CONCLUSIONS: Chelidonine, rotenone, and myricetin emerged as promising therapeutic candidates for chronic periodontitis due to their strong binding affinities, favorable ADME profiles, and lack of significant toxicity. The detailed pharmacophore modeling provided insights into the molecular mechanisms underpinning their inhibitory effects on the heme-binding protein of P. gingivalis. These findings suggest that these compounds have the potential for further development as effective treatments for chronic periodontitis. Future research should focus on in vitro and in vivo validation of these findings to confirm the efficacy and safety of these compounds in biological systems.

Erythrocyte-Mimicking Nanovesicle Targeting Porphyromonas gingivalis for Periodontitis.

Porphyromonas gingivalis has been demonstrated to have the strongest association with periodontitis. Within the host, P. gingivalis relies on acquiring iron and heme through the aggregation and lysis of erythrocytes, which are important factors in the growth and virulence of P. gingivalis. Additionally, the excess obtained heme is deposited on the surface of P. gingivalis, protecting the cells from oxidative damage. Based on these biological properties of the interaction between P. gingivalis and erythrocytes, this study developed an erythrocyte membrane nanovesicle loaded with gallium porphyrins to mimic erythrocytes. The nanovesicle can target and adhere with P. gingivalis precisely, being lysed and utilized by P. gingivalis as erythrocytes. Ingested gallium porphyrin replaces iron porphyrin in P. gingivalis, causing intracellular metabolic disruption. Deposited porphyrin generates a large amount of reactive oxygen species (ROS) under blue light, causing oxidative damage, and its lethality is enhanced by bacterial metabolic disruption, synergistically killing P. gingivalis. Our results demonstrate that this strategy can target and inhibit P. gingivalis, reduce its invasion of epithelial cells, and alleviate the progression of periodontitis.