Proteomic analysis ofPorphyromonas gingivalisexposed to nicotine and cotinine

Metatranscriptomic analysis shows functional alterations in subgingival biofilm in young smokers with periodontitis: a pilot study

OBJECTIVE

This study aimed to assess the influence of smoking on the subgingival metatranscriptomic profile of young patients affected by stage III/IV and generalized periodontal disease.

METHODOLOGY

In total, six young patients, both smokers and non-smokers (n=3/group), who were affected by periodontitis were chosen. The STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines for case-control reporting were followed. Periodontal clinical measurements and subgingival biofilm samples were collected. RNA was extracted from the biofilm and sequenced via Illumina HiSeq. Differential expression analysis used Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, and differentially expressed genes were identified using the Sleuth package in R, with a statistical cutoff of ≤0.05.

RESULTS

This study found 3351 KEGGs in the subgingival biofilm of both groups. Smoking habits altered the functional behavior of subgingival biofilm, resulting in 304 differentially expressed KEGGs between groups. Moreover, seven pathways were modulated: glycan degradation, galactose metabolism, glycosaminoglycan degradation, oxidative phosphorylation, peptidoglycan biosynthesis, butanoate metabolism, and glycosphingolipid biosynthesis. Smoking also altered antibiotic resistance gene levels in subgingival biofilm by significantly overexpressing genes related to beta-lactamase, permeability, antibiotic efflux pumps, and antibiotic-resistant synthetases.

CONCLUSION

Due to the limitations of a small sample size, our data suggest that smoking may influence the functional behavior of subgingival biofilm, modifying pathways that negatively impact the behavior of subgingival biofilm, which may lead to a more virulent community.

Effect of different forms of tobacco on the oral microbiome in healthy adults: a systematic review

Objective

The study aimed to evaluate the impact of tobacco use on the composition and functions of the oral microbiome in healthy adult humans.

Methods

We conducted a systematic search on PubMed, Web of Science, and Cinhal databases for literature published until 15 December 2023, to identify studies that have evaluated the oral microbiome with culture-independent next-generation techniques comparing the oral microbiome of tobacco users and non-users. The search followed the PECO format. The outcomes included changes in microbial diversity and abundance of microbial taxa. The quality assessment was performed using the Newcastle-Ottawa Scale (NOS) (PROSPERO ID CRD42022340151).

Results

Out of 2,435 articles screened, 36 articles satisfied the eligibility criteria and were selected for full-text review. Despite differences in design, quality, and population characteristics, most studies reported an increase in bacterial diversity and richness in tobacco users. The most notable bacterial taxa enriched in users were Fusobacteria and Actinobacteria at the phylum level and Streptococcus, Prevotella, and Veillonella at the genus level. At the functional level, more similarities could be noted; amino acid metabolism and xenobiotic biodegradation pathways were increased in tobacco users compared to non-users. Most of the studies were of good quality on the NOS scale.

Conclusion

Tobacco smoking influences oral microbial community harmony, and it shows a definitive shift towards a proinflammatory milieu. Heterogeneities were detected due to sampling and other methodological differences, emphasizing the need for greater quality research using standardized methods and reporting.

Systematic Review Registration

CRD42022340151.

Proteomic Profiling Reveals Cytotoxic Mechanisms of Action and Adaptive Mechanisms of Resistance in Porphyromonas gingivalis: Treatment with Juglans regia and Melaleuca alternifolia

The increasing trend in the rise of antibiotic-resistant bacteria pushes research to discover new efficacious antibacterial agents from natural and synthetic sources. Porphyromonas gingivalis is a well-known bacterium commonly known for causing periodontal disease, and it is associated with the pathogenesis of life-changing systemic conditions such as Alzheimer's. Proteomic research can be utilized to test new antibacterial drugs and understand the adaptive resistive mechanisms of bacteria; hence, it is important in the drug discovery process. The current study focuses on identifying the antibacterial effects of Juglans regia (JR) and Melaleuca alternifolia (MA) on P. gingivalis and uses proteomics to identify modes of action while exploring its adaptive mechanisms. JR and MA extracts were tested for antibacterial efficacy using the agar well diffusion assay. A proteomic study was conducted identifying upregulated and downregulated proteins compared to control by 2D-DIGE analysis, and proteins were identified using MADLI-TOF/MS. The bacterial inhibition for JR was 20.14 ± 0.2, and that for MA was 19.72 ± 0.5 mm. Out of 88 differentially expressed proteins, there were 17 common differentially expressed proteins: 10 were upregulated and 7 were downregulated in both treatments. Among the upregulated proteins were Arginine-tRNA ligase, ATP-dependent Clp protease proteolytic, and flavodoxins. In contrast, down-regulated proteins were ATP synthase subunit alpha and quinone, among others, which are known antibacterial targets. STRING analysis indicated a strong network of interactions between differentially expressed proteins, mainly involved in protein translation, post-translational modification, energy production, metabolic pathways, and protein repair and degradation. Both extracts were equi-efficacious at inhibiting P. gingivalis and displayed some overlapping proteomic profiles. However, the MR extract had a greater fold change in its profile than the JA extract. Downregulated proteins indicated similarity in the mode of action, and upregulated proteins appear to be related to adaptive mechanisms important in promoting repair, growth, survival, virulence, and resistance. Hence, both extracts may be useful in preventing P. gingivalis-associated conditions. Furthermore, our results may be helpful to researchers in identifying new antibiotics which may offset these mechanisms of resistance.

A Systematic Review of the Literature Examining the Effects of Cigarette Smoke and e-Cigarette Vapor on the Virulence of Human Pathogenic Bacteria

The bioactive chemicals in cigarette smoke (CS) and e-cigarette vapor (EV) may affect pathogenic bacteria in the nasopharyngeal microflora, which may have implications on the pathophysiology of respiratory infections in cigarette smokers and e-cigarette users. In this systematic review, we seek to synthesize the research evidence supporting this hypothesis. To address the central research question, "what is known from the published, peer-reviewed literature about the effects of cigarette smoke or e-cigarette vapor exposure on the physiology of human pathogenic bacteria?", we screened the PubMed^®, Web of Science^TM, and ScienceDirect databases for reports examining the virulence characteristics and gene expression in human pathogenic bacteria exposed to either CS or EV. The principal conclusion from our analysis is that exposure to either CS or EV induces the virulence of respiratory pathogenic bacteria in a strain-dependent manner, which may in turn facilitate respiratory infections in cigarette smokers and e-cigarette users. In addition, we present evidence that nicotine and reactive oxygen species are the main chemicals responsible for CS/EV-mediated alterations in bacterial physiology. We note limitations that this review does not examine reports describing the alterations in host respiratory physiology or nasopharyngeal dysbiosis caused by CS/EV exposure. Future research to determine whether CS/EV-mediated augmentation of bacterial virulence indeed plays a role in human respiratory tract infections is warranted.

The Impact of Smoking on Subgingival Plaque and the Development of Periodontitis: A Literature Review

Smoking seriously affects oral health and causes a variety of oral diseases. Numerous clinical data show that smoking significantly increases the risk of periodontitis, and the duration and amount of smoking are positively correlated with the severity of periodontitis. In fact, smoking creates an environment conducive to the colonization of periodontopathogens, which affects the process of periodontitis. Since subgingival plaque which harbors periodontopathogens is the initiation factor of periodontitis, it is critical to study the impact of smoking on subgingival microbiota for understanding the relationship between smoking and periodontitis. Continuous advances have been made on the understanding of effects of smoking on subgingival plaque and the development of periodontitis. Smoking is observed to enhance the pathogenicity of periodontopathogens, especially the red complex microorganisms, via promoting their colonization and infection, and regulating the expression and function of multiple virulence factors. Furthermore, smoking has a negative impact on periodontal microecological homeostasis, which is reflected in the decrease of commensal bacteria and the increase of periodontopathogens, as well as the changes in the interaction between periodontopathogens and their commensal microbes in subgingival biofilm, thus influencing the pathogenicity of the subgingival plaque. In summary, the mechanism of smoking on subgingival plaque microorganisms represented by the red complex and its effect on the periodontal microecology still need to be further explored. The relevant research results are of great significance for guiding the periodontal clinical treatment of smoking population. This review summarizes the effects and relevant mechanisms of smoking on subgingival plaque and the development of periodontitis.

The Synergistic Effect of Nicotine and Staphylococcus aureus on Peri-Implant Infections

Smoking is considered a key risk factor for implant survival; however, how it interacts with the pathogens in peri-implant infections is not clear. Here, we identified that nicotine, the key component of cigarette smoking, can interact with Staphylococcus aureus and synergistically induce peri-implant infections in a rat osteolysis model. The nicotine–S. aureus combination group increased the gross bone pathology, osteolysis, periosteal reactions, and bone resorption compared to the nicotine or S. aureus single treated group (p < 0.05). Nicotine did not promote the proliferation of S. aureus both in vitro and in vivo, but it can significantly upregulate the expression of staphylococcal protein A (SpA), a key virulence factor of S. aureus. The nicotine–S. aureus combination also synergistically activated the expression of RANKL (receptor activator of nuclear factor-kappa B ligand, p < 0.05) to promote the development of peri-implant infections. The synergistic effects between nicotine and S. aureus infection can be a new target to reduce the peri-implant infections.

Environmental factors and periodontal microbiome

Periodontal diseases are chronic inflammatory, multifactorial diseases where the major triggering factors for disease onset are bacteria and their toxins, but the major part of tissue destruction occurs as a result of host response towards the periodontal microbiome. Periodontal microbiome consists of a wide range of microorganisms including obligate and facultative anaerobes. In health, there is a dynamic balance between the host, environment, and the microbiome. Environmental factors, mainly tobacco smoking and psychological stress, disrupt the symbiotic relationship. Tobacco smoke and its components alter the bacterial surface and functions such as growth. Psychological stressors and stress hormones may affect the outcome of an infection by changing the virulence factors and/or host response. This review aims to provide currently available data on the effects of the major environmental factors on the periodontal microbiome.

Quercetin inhibits virulence properties of Porphyromas gingivalis in periodontal disease

Porphyromonas gingivalis is a causative agent in the onset and progression of periodontal disease. This study aims to investigate the effects of quercetin, a natural plant product, on P. gingivalis virulence properties including gingipain, haemagglutinin and biofilm formation. Antimicrobial effects and morphological changes of quercetin on P. gingivalis were detected. The effects of quercetin on gingipains activities and hemolytic, hemagglutination activities were evaluated using chromogenic peptides and sheep erythrocytes. The biofilm biomass and metabolism with different concentrations of quercetin were assessed by the crystal violet and MTT assay. The structures and thickness of the biofilms were observed by confocal laser scanning microscopy. Bacterial cell surface properties including cell surface hydrophobicity and aggregation were also evaluated. The mRNA expression of virulence and iron/heme utilization was assessed using real time-PCR. Quercetin exhibited antimicrobial effects and damaged the cell structure. Quercetin can inhibit gingipains, hemolytic, hemagglutination activities and biofilm formation at sub-MIC concentrations. Molecular docking analysis further indicated that quercetin can interact with gingipains. The biofilm became sparser and thinner after quercetin treatment. Quercetin also modulate cell surface hydrophobicity and aggregation. Expression of the genes tested was down-regulated in the presence of quercetin. In conclusion, our study demonstrated that quercetin inhibited various virulence factors of P. gingivalis.

Host-microbe interactions: Profiles in the transcriptome, the proteome, and the metabolome

Periodontal studies using transcriptomics, proteomics, and metabolomics encompass the collection of mRNA transcripts, proteins, and small-molecule chemicals in the context of periodontal health and disease. The number of studies using these approaches has significantly increased in the last decade and they have provided new insight into the pathogenesis and host-microbe interactions that define periodontal diseases. This review provides an overview of current molecular findings using -omic approaches that underlie periodontal disease, including modulation of the host immune response, tissue homeostasis, and complex metabolic processes of the host and the oral microbiome. Integration of these -omic approaches will broaden our perspective of the molecular mechanisms involved in periodontal disease, advancing and improving the diagnosis and treatment of various stages and forms of periodontal disease.

Effect of tobacco on periodontal disease and oral cancer

INTRODUCTION

Periodontal disease and oral cancer are common health hazards. Epidemiological investigations show that smoking, periodontal disease and oral cancer are closely related. Tobacco is one of the major risk factors for periodontitis and oral cancer.

METHODS

A systematic literature review was performed. To identify relevant studies, the following online databases were searched using specific keywords: PubMed, Web of Science and CNKI.

RESULTS

Tobacco not only possesses an addictive effect, but it aggravates periodontal disease by promoting the invasion of pathogenic bacteria, inhibiting autoimmune defense, aggravating the inflammatory reaction, and aggravating the loss of alveolar bone. According to current evidence, tobacco significantly aggravates the development and progression of periodontal disease and oral cancer, and periodontal disease may be related to the prevalence of oral cancer.

CONCLUSIONS

Clinicians should strongly recommend that smokers undertake a strategy to stop smoking to avoid the exacerbation of nicotine-related periodontal disease and to reduce the incidence of oral cancer.

Melatonin Receptor Agonists as the "Perioceutics" Agents for Periodontal Disease through Modulation of Porphyromonas gingivalis Virulence and Inflammatory Response

Aim

“Perioceutics” including antimicrobial therapy and host modulatory therapy has emerged as a vital adjunctive treatment of periodontal disease. Melatonin level was significantly reduced in patients with periodontal diseases suggesting melatonin could be applied as a potential “perioceutics” treatment of periodontal diseases. This study aims to investigate the effects of melatonin receptor agonists (melatonin and ramelteon) on Porphyromonas gingivalis virulence and Porphyromonas gingivalis-derived lipopolysaccharide (Pg-LPS)-induced inflammation.

Methods

Effects of melatonin receptor agonists on Porphyromonas gingivalis planktonic cultures were determined by microplate dilution assays. Formation, reduction, and viability of Porphyromonas gingivalis biofilms were detected by crystal violet staining and MTT assays, respectively. Meanwhile, biofilms formation was also observed by confocal laser scanning microscopy (CLSM). The effects on gingipains and hemolytic activities of Porphyromonas gingivalis were evaluated using chromogenic peptides and sheep erythrocytes. The mRNA expression of virulence and iron/heme utilization was assessed using RT-PCR. In addition, cell viability of melatonin receptor agonists on human gingival fibroblasts (HGFs) was evaluated by MTT assays. After pretreatment of melatonin receptor agonists, HGFs were stimulated with Pg-LPS and then release of cytokines (IL-6 and lL-8) was measured by enzyme-linked immunosorbent assay (ELISA).

Results

Melatonin and ramelteon did exhibit antimicrobial effects against planktonic culture. Importantly, they inhibited biofilm formation, reduced the established biofilms, and decreased biofilm viability of Porphyromonas gingivalis. Furthermore, they at sub-minimum inhibitory concentration (sub-MIC) concentrations markedly inhibited the proteinase activities of gingipains and hemolysis in a dose-dependent manner. They at sub-MIC concentrations significantly inhibited the mRNA expression of virulence factors (kgp, rgpA, rgpB, hagA, and ragA), while increasing the mRNA expression of ferritin (ftn) or hemolysin (hem). They did not show obvious cytotoxicity toward HGFs. They inhibited Pg-LPS-induced IL-6 and IL-8 secretion, which was reversed by luzindole, the melatonin receptor antagonist.

Conclusion

Melatonin receptor agonists can inhibit planktonic and biofilm growth of Porphyromonas gingivalis by affecting the virulent properties, as well as Pg-LPS-induced inflammatory response. Our study provides new evidence that melatonin receptor agonists might be useful as novel “perioceutics” agents to prevent and treat Porphyromonas gingivalis-associated periodontal diseases.