Peptostreptococcus micros cell wall elicits a pro-inflammatory response in human macrophages

Employing Cloning-Independent Mutagenesis of Parvimonas micra for the Study of Cell Wall Biogenesis

The cell wall plays an important structural role for bacteria and is intimately tied to a variety of critical processes ranging from growth and differentiation to pathogenesis. Our understanding of cell wall biogenesis is primarily derived from a relatively small number of heavily studied model organisms. Consequently, these processes can only be inferred for the vast majority of prokaryotes, especially among groups of uncharacterized and/or genetically intractable organisms. Recently, we developed the first tractable genetic system for Parvimonas micra, which is a ubiquitous Gram-positive pathobiont of the human microbiome involved in numerous types of inflammatory infections as well as a variety of malignant tumors. P. micra is also the first, and currently only, member of the entire Tissierellia class of the Bacillota phylum in which targeted genetic manipulation has been demonstrated. Thus, it is now possible to study cell wall biogenesis mechanisms within a member of the Tissierellia, which may also reveal novel aspects of P. micra pathobiology. Herein, we describe a procedure for cloning-independent genetic manipulation of P. micra, including allelic replacement mutagenesis and genetic complementation. The described techniques are also similarly applicable for the study of other aspects of P. micra pathobiology and physiology.

The role of bacterial infections in rheumatoid arthritis development and novel therapeutic interventions: Focus on oral infections

BACKGROUND

Rheumatoid arthritis (RA) represents a primary public health challenge, which is a major source of pain, disability, and socioeconomic effects worldwide. Several factors contribute to its pathogenesis. Infections are an important concern in RA patients, which play a key role in mortality risk. Despite major advances in the clinical treatment of RA, long-term use of disease-modifying anti-rheumatic drugs can cause serious adverse effects. Therefore, effective strategies for developing novel prevention and RA-modifying therapeutic interventions are sorely needed.

OBJECTIVE

This review investigates the available evidence on the interplay between various bacterial infections, particularly oral infections and RA, and focuses on some potential interventions such as probiotics, photodynamic therapy, nanotechnology, and siRNA that can have therapeutic effects.

Who is in the driver's seat? Parvimonas micra: An understudied pathobiont at the crossroads of dysbiotic disease and cancer

Recent advances in our understanding of microbiome composition at sites of inflammatory dysbiosis have triggered a substantial interest in a variety of historically understudied bacteria, especially among fastidious obligate anaerobes. A plethora of new evidence suggests that these microbes play outsized roles in establishing synergistic polymicrobial infections at many different sites in the human body. Parvimonas micra is a prime example of such an organism. Despite being almost completely uncharacterized at the genetic level, it is one of the few species commonly detected in abundance at multiple mucosal sites experiencing either chronic or acute inflammatory diseases, and more recently, it has been proposed as a discriminating biomarker for multiple types of malignancies. In the absence of disease, P. micra is commonly found in low abundance, typically residing within the oral cavity and gastrointestinal tract. P. micra exhibits the typical features of an inflammophilic organism, meaning its growth actually benefits from active inflammation and inflammatory tissue destruction. In this mini-review, we will describe our current understanding of this underappreciated but ubiquitous pathobiont, specifically focusing upon the role of P. micra in polymicrobial inflammatory dysbiosis and cancer as well as the key emerging questions regarding its pathobiology. Through this timely work, we highlight Parvimonas micra as a significant driver of disease and discuss its unique position at the crossroads of dysbiosis and cancer.

Modifiable risk factors for the development and progression of periodontal tissue diseases

In this review, an analysis of modifiable risk factors for the development and progression of periodontal tissue diseases was carried out. The review highlights the data on the relationship of periodontal infection, tobacco smoking, diabetes mellitus, cardiovascular disease, drug-induced periodontal tissue damage, stress, and obesity with the risk of developing and progression of periodontal tissue diseases. A rather detailed analysis of the mechanisms of pathogenic influence of the microflora of the oral cavity, including in the subgingival plaque, was carried out. The mechanisms of the pathological effect of smoking on the state of periodontal tissues are described. Data on the effect of periodontal treatment on glycemic control in patients with diabetes mellitus are presented. The article emphasizes the importance of the presence of periodontal diseases as a risk factor for cardiovascular and cerebrovascular diseases, describes the mechanisms of the mutual influence of cardiovascular pathology and the inflammatory process in the periodontium. In addition, the article presents the possibilities of the iatrogenic effect of systemic drugs on the state of periodontal tissues. The data on the influence of stress loads on the development of dental diseases are presented. The review article describes in detail the mechanisms of influence of overweight and obesity on the risks of development and progression of periodontal tissue diseases. Based on the results of the scientific research publications presented in the article, it can be stated that not only the dentist, but also doctors of other specialties need to work to change the modifiable risk factors for the development and progression of periodontal diseases.

Infection Route of Parvimonas micra: A Case Report and Systematic Review

Parvimonas micra (P. micra), a bacterium that colonizes the gastrointestinal tract, is often isolated from periodontitis and abscesses as part of a complex bacterial infection. However, reports of monobacterium infections due to P. micra are limited. Here, we report a case of monobacterial bacteremia caused by P. micra with the aim of identifying the source of the invasion and clarifying the clinical features. A 54-year-old patient presented with bacteremia due to P. micra and with an oral invasion that we suspected resulted from prior dental treatment. Using PubMed and Google Scholar databases, we undertook a systematic review of monobacteremia caused by P. micra. We identified 26 patients (mean age, 70.15 years) in our systematic review. P. micra bacteremia and its associated phenotypes were most frequently identified in spinal discitis, followed by epidural and lumbar abscesses, and infective endocarditis. The major risk factors were malignancy, diabetes mellitus, and post-arthroplasty. When P. micra is detected in blood cultures, evaluation and intervention for oral contamination may be indicated.

Inhibition of phosphodiesterase-4 in the spinal dorsal horn ameliorates neuropathic pain via cAMP-cytokine-Cx43 signaling in mice

Background

The spinal phosphodiesterase‐4 (PDE4) plays an important role in chronic pain. Inhibition of PDE4, an enzyme catalyzing the hydrolysis of cyclic adenosine monophosphate AMP (cAMP), produces potent antinociceptive activity. However, the antinociceptive mechanism remains largely unknown. Connexin43 (Cx43), a gap junction protein, has been shown to be involved in controlling pain transduction at the spinal level; restoration of Cx43 expression in spinal astrocytes to the normal levels reduces nerve injury‐induced pain. Here, we evaluate the novel mechanisms involving spinal cAMP‐Cx43 signaling by which PDE4 inhibitors produce antinociceptive activity.

Methods

First, we determined the effect of PDE4 inhibitors rolipram and roflumilast on partial sciatic nerve ligation (PSNL)‐induced mechanical hypersensitivity. Next, we observed the role of cAMP‐Cx43 signaling in the effect of PDE4 inhibitors on PSNL‐induced mechanical hypersensitivity.

Results

Single or repeated, intraperitoneal or intrathecal administration of rolipram or roflumilast significantly reduced mechanical hypersensitivity in mice following PSNL. In addition, repeated intrathecal treatment with either of PDE4 inhibitors reduced PSNL‐induced downregulation of cAMP and Cx43, and upregulation of proinflammatory cytokines tumor necrosis factor‐α (TNF‐α) and interleukin‐1β. Furthermore, the antinociceptive effects of PDE4 inhibitors were attenuated by the protein kinase A (PKA) inhibitor H89, TNF‐α, or Cx43 antagonist carbenoxolone. Finally, PSNL‐induced upregulation of PDE4B and PDE4D, especially the PDE4B subtype, was reduced by treatment with either of the PDE4 inhibitors.

Conclusions

The results suggest that the antinociceptive effect of PDE4 inhibitors is contributed by increasing Cx43 expression via cAMP‐PKA‐cytokine signaling in the spinal dorsal horn.

Oral Dysbiosis in Severe Forms of Periodontitis Is Associated With Gut Dysbiosis and Correlated With Salivary Inflammatory Mediators: A Preliminary Study

Inflammation is a driven force in modulating microbial communities, but little is known about the interplay between colonizing microorganisms and the immune response in periodontitis. Since local and systemic inflammation may play a whole role in disease, we aimed to evaluate the oral and fecal microbiome of patients with periodontitis and to correlate the oral microbiome data with levels of inflammatory mediator in saliva. Methods: Nine patients with periodontitis (P) in Stage 3/Grade B and nine age-matched non-affected controls (H) were evaluated. Microbial communities of oral biofilms (the supra and subgingival from affected and non-affected sites) and feces were determined by sequencing analysis of the 16SrRNA V3-V4 region. Salivary levels of 40 chemokines and cytokines were correlated with oral microbiome data. Results: Supragingival microbial communities of P differed from H (Pielou's evenness index, and Beta diversity, and weighted UniFrac), since relative abundance (RA) of Defluviitaleaceae, Desulfobulbaceae, Mycoplasmataceae, Peptostreococcales-Tissierellales, and Campylobacteraceae was higher in P, whereas Muribaculaceae and Streptococcaceae were more abundant in H. Subgingival non-affected sites of P did not differ from H, except for a lower abundance of Gemellaceae. The microbiome of affected periodontitis sites (PD ≥ 4 mm) clustered apart from the subgingival sites of H. Oral pathobionts was more abundant in sub and supragingival biofilms of P than H. Fecal samples of P were enriched with Acidaminococcus, Clostridium, Lactobacillus, Bifidobacterium, Megasphaera, and Romboutsia when compared to H. The salivary levels of interleukin 6 (IL-6) and inflammatory chemokines were positively correlated with the RA of several recognized and putative pathobionts, whereas the RA of beneficial species, such as Rothia aeria and Haemophilus parainfluenzae was negatively correlated with the levels of Chemokine C-C motif Ligand 2 (CCL2), which is considered protective. Dysbiosis in patients with periodontitis was not restricted to periodontal pockets but was also seen in the supragingival and subgingival non-affected sites and feces. Subgingival dysbiosis revealed microbial signatures characteristic of different immune profiles, suggesting a role for candidate pathogens and beneficial organisms in the inflammatory process of periodontitis.

Parvimonas micra Necrotizing Panophthalmitis Involving the Sclera, Cornea, Uvea, Retina, and Orbit

We present an unusual case of a patient who acquired a pansinusitis and orbital cellulitis with necrotizing features, subsequently developing scleritis, keratitis, and anterior uveitis. To date, there are no reported cases of the simultaneous involvement of these ocular structures from a pansinusitis. Our patient was urgently taken to the operating room for drainage of the abscesses within his sinuses and the orbit. Intraoperative cultures were positive for Parvimonas micra, an odontogenic anaerobic bacteria. He was additionally found to have a central retinal artery occlusion. He was treated with systemic and topical antibiotics as well as topical dilute hypochlorous acid. The mechanisms of virulence of P. micra, including its synergistic relationship with other bacteria, ability to bind plasminogen, and its expression of proteases, contributed to this diffuse infection.

Prevalence of red and orange microbial complexes in endodontic-periodontal lesions: a systematic review and meta-analysis

OBJECTIVE

This systematic review assesses the prevalence of microbial complexes in endodontic-periodontal lesion.

MATERIALS AND METHODS

Nine databases were searched through August 2020. Experts were consulted to indicate additional studies. Studies were blindly selected by two reviewers based on pre-defined eligibility criteria. Studies that evaluated the prevalence of microbial orange and red complexes among patients with endodontic-periodontal lesion were considered eligible. Risk of bias was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Studies Reporting Prevalence Data.

RESULTS

From 572 articles found on all databases, 11 clinical studies were finally included. The following microorganisms were investigated: P. gingivalis, T. forsythia, T. denticola, F. nucleatum, F. periodonticum, P. micra, P. intermedia, P. nigrescens, S. constellatus, C. gracilis, C. rectus, C. showae and E. nodatum. Considering the orange complex, P. micra, E. nodatum and S. constellatus were prevalent in both root canal and periodontal pockets. P. gingivalis and T. forsythia belonging to the red complex were prevalent only in periodontal pockets. The red complex microorganisms were not found very frequently in root canal.

CONCLUSIONS

There is a similarity between the microbiome of root canal and periodontal pockets, with prevalence of the three microorganisms of the orange complex. Two microorganisms from the red complex were prevalent only in periodontal pockets.

CLINICAL RELEVANCE

The prevalence of specific microorganisms in endodontic-periodontal lesion is important to understand the microbiological profile of the patients involved and to correlate it with possible clinical and repair conditions of this pathology.

Bacteria and virulence factors in periapical lesions associated with teeth following primary and secondary root canal treatment

AIM

This cross-sectional study aimed to investigate the microbial profile and to quantify the levels of endotoxins (LPS) and lipoteichoic acid (LTA) present in periapical lesions associated with root filled teeth and those that had received root canal retreatment. It also aimed to investigate the association between microorganisms and their virulence factors with clinical and radiographic features.

METHODOLOGY

Patients with periapical lesions in teeth with post-treatment endodontic disease following primary root canal treatment (n = 19) and unsuccessful root canal retreatment (n = 13) were treatment planned for endodontic microsurgery, where the periapical lesions were collected. Clinical and radiographic data were also collected. For microbiological analysis, nested polymerase chain reaction was used to detect 17 bacterial species. Levels of LPS and LTA were determined using limulus amebocyte lysate and enzyme-linked immunosorbent assays, respectively. The Student t-test or Wilcoxon-Mann-Whitney tests were applied to compare the data on LPS and LTA with clinical and radiographic features. The associations between the clinical and radiographic features and the bacterial species were analysed using the Fisher's exact test. A significance level of 5% was adopted.

RESULTS

Bacterial DNA, LPS and LTA were detected in all samples. Parvimonas micra was the most commonly detected species in all groups, followed by Enterococcus faecalis, Fusobacterium nucleatum and Porphyromonas endodontalis. The type of endodontic treatment, whether a primary root canal treatment or retreatment, was not associated with the presence of any bacterial species in periapical lesions. The levels of LPS and LTA in periapical lesions of root filled teeth were not significantly different from those that had been retreated. Associations between the levels of LPS and LTA with clinical signs and symptoms were found. No association was found between specific bacteria and clinical features.

CONCLUSION

Periapical lesions associated with teeth after primary root canal treatment and retreatment had similar polymicrobial composition. The levels of LPS and LTA in periapical lesions associated with teeth after primary root canal treatment and retreatment were similar, and both were associated with the same symptomatology.

Choosing the Right Essential Oil for a Mouthwash: Chemical, Antimicrobial and Cytotoxic Studies

Thirteen commercial essential oils were assessed for their possible inclusion in a mouthwash formulation based on their inhibitory effect against potentially pathogenic anaerobic oral bacterial isolates from subgingival plaque, and their cytotoxicity towards gingival cells. The essential oils, originating from species belonging to seven major aromatic plant families, were chosen to provide the necessary diversity in chemical composition that was analyzed in detail by GC and GC/MS. Multivariate statistical analysis, performed using the in vitro microbiological/toxicological assays and compositional data, revealed that the major components of the essential oils were probably not the main carriers of the activities observed. A formulation of 'designer' mouthwashes is proposed based on the selective action of certain essential oils towards specific bacterial isolates (e. g., Citrus bergamia vs. Parvimonas micra), and non-toxicity to gingival cells at antimicrobially active concentrations.

Microbiota of alveolar osteitis after permanent tooth extractions: A systematic review

Alveolar osteitis (AO) or dry socket after dental extractions is a common postoperative complication characterized by the presence of severe pain associated with an empty socket. Although some authors consider AO to be related to an alteration of the blood clot, the underlying etiology remains unclear, and recent reports suggest that bacteria might play an important role. A systematic review was made, compiling relevant references from PubMed, the Cochrane Library, Scopus and the Web of Science databases to determine which bacteria have been identified in AO sockets after dental extractions. Papers published between 1980-2019, identifying the bacteria present in AO sockets after tooth extractions, were included. Data were displayed in tables, and a descriptive analysis was carried out. After the screening process, four papers were analyzed, comprising a total of 138 samples from 138 patients with AO. The most commonly detected bacteria were Prevotella, Fusobacterium, Parvimonas and Peptostreptococcus. Two studies also showed the microbiota of patients that developed AO after dental extractions to be apparently different from that of patients without postoperative complications. These results indicate that bacteria may play an important role in the pathogenesis of AO, though further studies are needed to confirm these findings.

Periodontal pathogenic bacteria among high school children in Saudi Arabia

BACKGROUND

The periodontal tissues are continuously exposed to specific bacterial components that have the ability to alter many local functions. Normal endogenous infections in healthy mouths cause disease when their numbers increase significantly.

OBJECTIVE

Determine the percentage of different periodontal pathogenic bacteria and their association with periodontal status.

DESIGN

Cross-sectional, analytical.

SETTINGS

School children of both genders in Saudi Arabia.

PATIENTS AND METHODS

Clinical examination consisted of measurement of the gingival and periodontal supporting tissue including attachment loss, probing pocket depth and furcation involvement following the National Health and Nutrition Examination Survey (NHANES) and taking samples of the subgingival bacterial flora.

MAIN OUTCOME MEASURES

The percentage of periodontal pathogenic bacteria and its association with periodontal status in Saudi Arabia.

SAMPLE SIZE

Bacterial samples were collected from 277 subjects.

RESULTS

Aggregatibacter actinomycetemcomitans was present in 21.7% of the subjects, Porphyromonas gingivalis in 21.3%; Tannerella forsythia in 10.1%; Treponema denticola in 34.7% and Prevotella inter-media in 12.3%. The red complex bacteria were found in 2.9% of the subjects.

CONCLUSIONS

The percentages of bacteria varied but only T denticola was significantly associated with periodontal breakdown. In addition, the presence of more than 2 of the 5 species tested were significantly associated with tissue damage.

LIMITATIONS

Cannot be generalized to all of Saudi Arabia. Larger controlled studies are needed.

CONFLICT OF INTEREST

None.

High-Throughput Sequencing Analysis of Microbial Profiles in the Dry Socket

PURPOSE

The aim of this study was to explore and describe the microbial profiles of dry socket (DS) and identify the key microbial population as a possible disease-related factor.

MATERIALS AND METHODS

Bacterial samples were collected from patients who underwent surgical mandibular third molar extraction and were divided in 3 groups: the disease (D) group composed of patients who were diagnosed with DS; the treated (T) group composed of patients from the D group who received treatment; and the control (C) group composed of patients who did not have adverse reactions after tooth extraction. Bacterial DNA was extracted and the V3 and V4 hypervariable regions of the bacterial 16S rRNA gene were amplified and subjected to sequencing. Sequence data were analyzed using alpha and beta diversity indices.

RESULTS

In total, 772,169 high-quality sequences were detected from 31 samples. Using a 97% similarity level, 531 operational taxonomic units were detected. In addition, 10 phyla, 23 classes, 38 orders, 63 families, and 116 genera were found. Composition of the microbial community in the D group differed considerably from that of the T and C groups. Furthermore, a specific microbial pattern, which included Parvimonas, Peptostreptococcus, Prevotella, Fusobacterium, Slackia, Oribacterium, and Solobacterium species, appeared abundantly in the D group compared with the T and C groups. Moreover, Parvimonas, Peptostreptococcus, Prevotella, and Fusobacterium species had important roles in discriminating the D group from the other 2 groups.

CONCLUSION

These results suggest differences in the microbial community composition among DSs, normal-healing sockets, and post-treated sockets. These results provide better insight into the development of DS and enhance the understanding of DS. Nonetheless, further studies are necessary to investigate and confirm how these differential bacteria contribute to the development of the disease.

Selected Topics in Anaerobic Bacteriology

Alteration in the host microbiome at skin and mucosal surfaces plays a role in the function of the immune system, and may predispose immunocompromised patients to infection. Because obligate anaerobes are the predominant type of bacteria present in humans at skin and mucosal surfaces, immunocompromised patients are at increased risk for serious invasive infection due to anaerobes. Laboratory approaches to the diagnosis of anaerobe infections that occur due to pyogenic, polymicrobial, or toxin-producing organisms are described. The clinical interpretation and limitations of anaerobe recovery from specimens, anaerobe-identification procedures, and antibiotic-susceptibility testing are outlined. Bacteriotherapy following analysis of disruption of the host microbiome has been effective for treatment of refractory or recurrent Clostridium difficile infection, and may become feasible for other conditions in the future.

Prevalence of Actinomyces spp. in patients with chronic periodontitis

This study investigated the prevalence of Actinomyces spp. in shallow, deep and very deep pockets of patients with chronic periodontitis compared to healthy controls and correlated the results with clinical status. Twenty patients with chronic periodontitis and 15 healthy subjects were enrolled in this study. Clinical indices were recorded in a six-point measurement per tooth. From each patient samples of supra and subgingival plaque were taken separately from teeth with shallow, deep and very deep pockets. Samples of supragingival plaque and sulcular microflora were collected from the healthy subjects. All the samples were cultivated on different media at 37̊C in an anaerobic atmosphere for 7 days. All the suspect colonies were identified using a rapid ID 32 A system (bioMèrieux) and MALDI-TOF-MS analysis using an Autoflex II Instrument (Bruker Daltonics) together with in house developed identification software and a reference spectra database. A total of 977 strains were identified as Actinomyces. Actinomyces naeslundii/oris/johnsonii (430 isolates) was the most prevalent species and was found in all patients and in almost all of the healthy subjects. Significant differences (p=0.003) between the groups were found for Actinomyces odontolyticus/meyeri and Actinomyces israelii which were associated with periodontitis patients. Actinomyces dentalis was found in higher percentage (p=0.015) in the periodontitis group. Actinomyces gerencseriae and Actinomyces massiliensis were significantly more often found supragingivally than subgingivally (p=0.004, p=0.022, respectively) in the periodontitis group. Whether some Actinomyces species, definitely important plaque formers, are actively involved in the pathogenicity of chronic periodontitis needs further investigation.

Risk factors of periodontal disease: review of the literature

Objectives. This paper aims to review the evidence on the potential roles of modifiable and nonmodifiable risk factors associated with periodontal disease. Data. Original articles that reported on the risk factors for periodontal disease were included. Sources. MEDLINE (1980 to Jan 2014), PubMed (using medical subject headings), and Google Scholar were searched using the following terms in different combinations: "periodontal disease," "periodontitis," "risk factors," and "causal." This was supplemented by hand-searching in peer-reviewed journals and cross-referenced with the articles accessed. Conclusions. It is important to understand the etiological factors and the pathogenesis of periodontal disease to recognize and appreciate the associated risk factors. As periodontal disease is multifactorial, effective disease management requires a clear understanding of all the associated risk factors.

Macrophage Infiltrate Is Elevated in CRSwNP Sinonasal Tissue Regardless of Atopic Status

Objective

Macrophages are major producers of inflammatory cytokines; however, their role in chronic rhinosinusitis (CRS) has not been clearly defined. The aim of this study was to quantify macrophages in sinus tissue of patients with various subtypes of CRS and determine the impact of atopic status on macrophage infiltrate.

Study Design

Prospective immunohistochemical study of human sinonasal tissue.

Setting

Academic medical center.

Subjects and Methods

Human sinonasal tissue was taken from patients with CRS with nasal polyposis (CRSwNP, n = 8), CRS without nasal polyposis (CRSsNP, n = 8), and controls (n = 8) undergoing surgery for CSF leak repair or endoscopic excision of non-secreting pituitary tumor. Samples were immunohistochemically stained for macrophage/monocyte markers Mac387 and CD68.

Results

CRSwNP patients had significantly increased numbers of Mac387 and CD68 cells compared to control patients ( P < .05) or CRSsNP patients ( P < .01). CRSsNP had significantly increased number of cells staining for CD68 compared to controls ( P < .05). The increased presence of macrophages measured by either marker in CRSwNP was independent of atopic status.

Conclusion

Macrophages are increased in CSRwNP patients regardless of atopic status and may contribute to the immunopathology of CRS.

Gram-positive anaerobic cocci--commensals and opportunistic pathogens

Among the Gram-positive anaerobic bacteria associated with clinical infections, the Gram-positive anaerobic cocci (GPAC) are the most prominent and account for approximately 25-30% of all isolated anaerobic bacteria from clinical specimens. Still, routine culture and identification of these slowly growing anaerobes to the species level has been limited in the diagnostic laboratory, mainly due to the requirement of prolonged incubation times and time-consuming phenotypic identification. In addition, GPAC are mostly isolated from polymicrobial infections with known pathogens and therefore their relevance has often been overlooked. However, through improvements in diagnostic and in particular molecular techniques, the isolation and identification of individual genera and species of GPAC associated with specific infections have been enhanced. Furthermore, the taxonomy of GPAC has undergone considerable changes over the years, mainly due to the development of molecular identification methods. Existing species have been renamed and novel species have been added, resulting in changes of the nomenclature. As the abundance and significance of GPAC in clinical infections grow, knowledge of virulence factors and antibiotic resistance patterns of different species becomes more important. The present review describes recent advances of GPAC and what is known of the biology and pathogenic effects of Anaerococcus, Finegoldia, Parvimonas, Peptoniphilus and Peptostreptococcus, the most important GPAC genera isolated from human infections.

Expression levels of matrix metalloproteinase (MMP)-9 and its specific inhibitor TIMP-1, in septic and aseptic arthritis of the knee

PURPOSE

In cases of septic knee arthritis, there is excess of matrix metalloproteinases (MMPs) over tissue inhibitors of metalloproteinases (TIMPs), due to enhanced expression and activation that are induced by bacteria in comparison with rheumatic or degenerative arthritis. The aim of this study was to explore the expression levels of synovial gelatinase MMP-9 and its specific inhibitor TIMP-1 in septic and aseptic arthritis and their potential use as additional aids to clinical investigation.

METHODS

Gelatin zymography and western blot analysis were applied in effusions from knees of the patients with septic (SA-10 patients), rheumatic (RA-10 patients) and osteoarthritis (OA-10 patients).

RESULTS

Zymographic analysis revealed that all samples contained latent MMP-2 activity, albeit activated MMP-2 appeared in more of the septic than aseptic effusions. MMP-9 was not detected in osteoarthritic synovial fluid samples. Only trace amounts of MMP-9 activity were detected in 4 of 10 patients with RA, whereas higher MMP-9 levels were evident in all samples from SA (P = 0.0241). In immunoblotting assays, samples from SA showed significantly higher levels of MMP-9 compared with samples from RA (P = 0.0052), confirming zymographic results. Although no significant difference in TIMP-1 levels was observed, the estimated MMP-9/TIMP-1 ratio of septic effusions was significantly higher compared with aseptic ones (P = 0.0029).

CONCLUSIONS

The data presented suggest enhanced expression and activation of MMP-9 in septic native knee arthritis compared with aseptic. The presence of high levels of MMP-9 with concomitantly increased MMP-9/TIMP-1 ratio and activated gelatinases in effusions, independent of neutrophilic counts, may be indicative for infection.

Microbial diversity in saliva of oral squamous cell carcinoma

In the oral cavity, chronic inflammation has been observed at various stages of oral squamous cell carcinomas (OSCC). Such inflammation could result from persistent mucosal or epithelial cell colonization by microorganisms. There is increasing evidence of the involvement of oral bacteria in inflammation, warranting further studies on the association of bacteria with the progression of OSCC. The objective of this study was to evaluate the diversity and relative abundance of bacteria in the saliva of subjects with OSCC. Using 454 parallel DNA sequencing, ∼58,000 PCR amplicons that span the V4-V5 hypervariable region of rRNAs from five subjects were sequenced. Members of eight phyla (divisions) of bacteria were detected. The majority of classified sequences belonged to the phyla Firmicutes (45%) and Bacteroidetes (25%). Further, 52 different genera containing approximately 860 (16.51%) known species were identified and 1077 (67%) sequences belonging to various uncultured bacteria or unclassified groups. The species diversity estimates obtained with abundance-based coverage estimators and Chao1 were greater than published analyses of other microbial profiles from the oral cavity. Fifteen unique phylotypes were present in all three OSCC subjects.

Subgingival microbial profiles of smokers with periodontitis

The subgingival microbiome is largely uncultivated, and therefore, cultivation-based and targeted molecular approaches have limited value in examining the effect of smoking on this community. We tested the hypothesis that the subgingival biofilm is compositionally different in current and never-smokers by using an open-ended molecular approach for bacterial identification. Subgingival plaque from deep sites of current and never-smokers matched for disease was analyzed by 16S sequencing. Smokers demonstrated greater abundance of Parvimonas, Fusobacterium, Campylobacter, Bacteroides, and Treponema and lower levels of Veillonella, Neisseria, and Streptococcus. Several uncultivated Peptostreptococci, Parvimonas micra, Campylobacter gracilis, Treponema socranskii, Dialister pneumosintes, and Tannerella forsythia were elevated in this group, while Veillonella sp. oral clone B2, Neisseria sp. oral clone 2.24, Streptococcus sanguinis, and Capnocytophaga sp. clone AH015 were at lower levels. The microbial profile of smoking-associated periodontitis is distinct from that of non-smokers, with significant differences in the prevalence and abundance of disease-associated and health-compatible organisms.

1-Nitropyrene (1-NP) induces apoptosis and apparently a non-apoptotic programmed cell death (paraptosis) in Hepa1c1c7 cells

Mechanistic studies of nitro-PAHs (polycyclic aromatic hydrocarbons) of interest might help elucidate which chemical characteristics are most important in eliciting toxic effects. 1-Nitropyrene (1-NP) is the predominant nitrated PAH emitted in diesel exhaust. 1-NP-exposed Hepa1c1c7 cells exhibited marked changes in cellular morphology, decreased proliferation and different forms of cell death. A dramatic increase in cytoplasmic vacuolization was observed already after 6 h of exposure and the cells started to round up at 12 h. The rate of cell proliferation was markedly reduced at 24 h and apoptotic as well as propidium iodide (PI)-positive cells appeared. Electron microscopic examination revealed that the vacuolization was partly due to mitochondria swelling. The caspase inhibitor Z-VAD-FMK inhibited only the apoptotic cell death and Nec-1 (an inhibitor of necroptosis) exhibited no inhibitory effects on either cell death or vacuolization. In contrast, cycloheximide markedly reduced both the number of apoptotic and PI-positive cells as well as the cytoplasmic vacuolization, suggesting that 1-NP induced paraptotic cell death. All the MAPKs; ERK1/2, p38 and JNK, appear to be involved in the death process since marked activation was observed upon 1-NP exposure, and their inhibitors partly reduced the induced cell death. The ERK1/2 inhibitor PD 98057 completely blocked the induced vacuolization, whereas the other MAPKs inhibitors only had minor effects on this process. These findings suggest that 1-NP may cause apoptosis and paraptosis. In contrast, the corresponding amine (1-aminopyrene) elicited only minor apoptotic and necrotic cell death, and cells with characteristics typical of paraptosis were absent.