The Oral-Gut Axis: Periodontal Diseases and Gastrointestinal Disorders

One of the prospective sequelae of periodontal disease (PD), chronic inflammation of the oral mucosa, is the development of inflammatory gastrointestinal (GI) disorders due to the amplification and expansion of the oral pathobionts. In addition, chronic inflammatory diseases related to the GI tract, which include inflammatory bowel disease (IBD), can lead to malignancy susceptibility in the colon of both animals and humans. Recent studies suggest that dysbiosis of the oral microbiota can alter the microbial composition in relative abundance or diversity of the distal gut, leading to the progression of digestive carcinogenesis. The link between PD and specific GI disorders is also closely associated with the migration and colonization of periodontal pathogens and the subsequent microbe-reactive T cell induction within the intestines. In this review, an in-depth examination of this relationship and the accessibility of different mouse models of IBD and PD may shed light on the current dogma. As such, oral microbiota dysbiosis involving specific bacteria, including Fusobacterium nucleatum and Porphyromonas gingivalis, can ultimately lead to gut malignancies. Further understanding the precise mechanism(s) of the oral-gut microbial axis in PD, IBD, and colorectal cancer pathogenesis will be pivotal in diagnosis, prognosis, and future treatment.

Laser Treatment of Peri-Implantitis: A Systematic Review of Radiographic Outcomes

(1) Background: This systematic review aimed to evaluate the effects of laser therapy on radiographic bone level (RBL) changes in peri-implantitis defects. (2) Methods: A literature search with defined inclusion criteria was performed. PubMed, Web of Science, Cochrane Library, and Google Scholar were searched through September 2020. The evaluated primary outcomes were RBL changes. In studies that reported RBL data, corresponding secondary clinical outcomes were probing depth (PD), bleeding on probing (BOP), and clinical attachment level (CAL). (3) Results: Thirteen articles were selected for data extraction and risk of bias assessment. Eight studies showed evidence of RBL gain in the laser groups compared to baseline, but did not report the statistical significance. Eight of these 13 studies reported comparisons to control. Five of the eight studies did not show RBL gain in the laser groups compared to control. In the laser groups compared to baseline, 11 of 13 reported reduced PD, and 6 of 13 reported significantly reduced BOP. Compared to the control, eight of the eight reported reduction of PD, and three of six reported significantly reduced BOP. Statistical significance was not consistently reported. (4) Conclusions: Within the limits of this systematic review, laser treatment may promote bone gain in peri-implantitis defects, may reduce BOP and PDs, and may be comparable to mechanical therapy. However, definitive conclusions can only be made with statistically significant data, which were found lacking in the currently available studies. This systematic review was registered with the National Institute for Health Research, international prospective register of systematic reviews (PROSPERO): CRD42020207972.

Presence of Specific Periodontal Pathogens in Prostate Gland Diagnosed With Chronic Inflammation and Adenocarcinoma

Background

Intraprostatic inflammation is frequently observed in the prostate and linked to prostatic diseases, including prostatitis, benign prostatic hyperplasia (BPH), and cancer. The etiology of prostate diseases is unclear. Periodontal diseases are associated with an increased risk of prostate diseases. In men, chronic prostatitis and moderate/severe periodontitis have significantly elevated serum prostate-specific antigen (PSA) levels. Treatment of periodontal disease reduced PSA levels in men. The presence of periodontal pathogens deoxyribonucleic acid (DNA) was identified in the prostate fluid of prostatitis patients. These pathogenic bacteria might have the potential to trigger prostatitis progressing to prostatic adenocarcinoma. The mechanism(s) explaining the etiology of association between periodontal disease and prostate cancer remains unclear. However, the presence of periodontal pathogens has not been analyzed in the prostate gland.

Objective

To identify and compare the presence of specific periodontal pathogens in the areas of BPH, inflammation, and cancer of the prostate glands diagnosed with malignancy.

Materials and methods

Whole-mount radical prostatectomy sections from men (n=30) were identified for BPH, inflammation, and cancer areas and marked for tissue procurement. The tissues were subjected to DNA isolation and analysis of microbial DNA and total bacterial load for the following pathogens, including Porphyromonas gingivalis strain ATCC 33277, Prevotella intermedia strain B422, Treponema denticola strain 35405, Fusobacterium nucleatum subsp. fusiform strain, Tannerella forsythia strain ATCC 43037, and Campylobacter​​​​​​​ rectus strain ATCC 33238performed real-time PCR. The universal bacterial primer pairs were used to detect genomic DNA (gDNA) from the total bacteria present in the samples. All species-specific primers were designed to target the variable regions of the 16S ribosomal RNA (rRNA). Data were analyzed using the 2-ΔΔCT method, statistically validated using unpaired t-test and ANOVA test.

Results

A total of 90 samples of prostate tissue specimens were analyzed for periodontal pathogens; only one pathogen (F. nucleatum subsp. fusiform strain ATCC 51190) showed a significant difference compared to the expression of S. epidermidis (internal control). In particular, F. nucleatum expression was 9, 11.9, and 10.3-fold higher in BPH, inflammation, and cancer, respectively, at p-value <0.05. Moreover, the bacterial load abundance/expression was almost similar in BPH (46.8-fold), inflammation (40.9 fold), and cancer (41.5 fold) higher. There was no significant difference in bacterial load (folder change) among the three areas of BPH, inflammation, and cancer (p-valve>0.05). Similarly, there was no significant difference between F. nucleatum (folder change) among the three areas (p-valve>0.05).

Conclusion 

Fusobacterium nucleatum is identified in the prostates that harbor cancer, chronic inflammation, and BPH.

The Association between Inflammatory Bowel Disease and Periodontal Conditions: Is There a Common Bacterial Etiology?

INTRODUCTION

The gastrointestinal system is strongly associated with the oral mucosa including periodontal tissues. Infl ammatory bowel disease (IBD) has two common forms: Crohn's disease (CD) and ulcerative colitis (UC). Local inflammation in periodontal diseases (PD) has an impact on infl ammatory diseases in various parts of the body. The existence of periodontitis in IBD patients suggests the possibility that the two inflammatory conditions may have common pathogenic pathways. Both diseases are multifactorial conditions in which genetic and environmental factors initiate and maintain the chronic inflammatory response.

AIM

The aim of this review was to determine the current state of understanding of the characteristics and mechanisms underlying the association between IBD and periodontal diseases, with emphasis on the role of microorganisms.

METHODS

A computer-assisted MEDLINE search was performed to find the relevant articles concerning IBD and periodontal diseases published until September 2016.

RESULTS AND CONCLUSION

A number of studies have showed an association between PD and IBD. Both diseases share genetic and environmental etiological factors. The precise role of intestinal bacteria remains vague. The periodontal microbiota that might be involved in the association of these diseases are Fusobacterium nucleatum, Campylobacter rectus and Campylobacter concisus. Fungal and viral microbiota dysbiosis should also be evaluated as common pathogenic pathways in IBD and periodontal disease.

Osteopontin attenuation of dextran sulfate sodium-induced colitis in mice

Osteopontin (OPN) is a matricellular cytokine present in most tissues and body fluids; it is known to modulate immune responses. In previous studies using the dextran sulfate sodium (DSS) acute colitis model, we found exacerbated tissue destruction and reduced repair in OPN-null ((-/-)) mice compared with wild-type (WT) controls. As OPN is normally present in milk, we hypothesized that administration of OPN may protect the intestines from the adverse effects of experimental colitis. A volume of 20 or 2 microg/ml bovine milk OPN, dissolved in drinking water, was given to mice 24 h before, and during administration of DSS. Clinical parameters of colitis and neutrophil functions were analyzed as previously reported. Orally administered OPN was absorbed and detected in the colon mucosa by immunohistochemistry. The 20 microg/ml OPN- and DSS-treated WT mice showed 37% less weight loss and reduced colon shortening and spleen enlargements than control mice (P<0.05). OPN administration also reduced the disease activity index, improved red blood cell counts, and reduced gut neutrophil activity compared with the DSS-treated WT mice that were not administered OPN (P<0.05). Immunohistochemical detection of F4/80-labelled cells (macrophages) was also less frequent. The level of transforming growth factor beta1 (TGF-beta1) was increased and the levels of pro-inflammatory mediators decreased in colon tissue samples of OPN-treated mice analyzed by ELISA. The reversal of experimental colitis parameters by exogenous OPN was not as robust in the OPN(-/-) mice. Administration of prokaryotic-expressed recombinant OPN and bovine serum albumin were ineffective. This study shows that administration of a physiological concentration of milk OPN in drinking water ameliorates the destructive host response in DSS-induced acute colitis.

Role of osteopontin in neutrophil function

Osteopontin (OPN) is important for the function of fibroblasts, macrophages and lymphocytes during inflammation and wound healing. In recent studies of experimental colitis we demonstrated exacerbated tissue destruction in OPN-null mice, associated with reduced tumour necrosis factor-alpha expression and increased myeloperoxidase activity. The objective of this investigation therefore was to determine the importance of OPN expression in neutrophil function. Although, in contrast to macrophages, neutrophils expressed low levels of OPN with little or no association with the CD44 receptor, intraperitoneal recruitment of neutrophils in OPN-null mice was impaired in response to sodium periodate. The importance of exogenous OPN for neutrophil recruitment was demonstrated by a robust increase in peritoneal infiltration of PMNs in response to injections of native or recombinant OPN. In vitro, OPN(-/-) neutrophils exhibited reduced chemokinesis and chemotaxis towards N-formyl methionyl leucyl phenylalanine (fMLP), reflecting a reduction in migration speed and polarization. Exogenous OPN, which was chemotactic for the neutrophils, rescued the defects in polarization and migration speed of the OPN(-/-) neutrophils. In contrast, the defensive and cytocidal activities of OPN(-/-) neutrophils, measured by assays for phagocytosis, generation of reactive oxygen species, cytokine production and matrix metalloproteinase-9, were not impaired. These studies demonstrate that, while exogenous OPN may be important for the recruitment and migration of neutrophils, expression of OPN by neutrophils is not required for their destructive capabilities.

Induction of de novo subcortical actin filament assembly by Treponema denticola major outer sheath protein

Treponema denticola and its major outer sheath protein (Msp) induce actin reorganization in fibroblasts. We adapted a barbed-end labeling/imaging assay to monitor Msp-induced subcortical actin filament assembly in neutrophils and fibroblasts. Msp, at an actin-reorganizing concentration, inhibited migration of these dissimilar cell types, whose cytoskeletal functions in locomotion and phagocytosis are crucial for immunity and healing of peripheral infections.

The major outer sheath protein of Treponema denticola inhibits the binding step of collagen phagocytosis in fibroblasts

Bacterial infections contribfute to the chronicity of connective tissue lesions in part by perturbing extracellular matrix remodelling processes. We examined a novel mechanism by which the major outer sheath protein (Msp) of the spirochaete Treponema denticola disrupts matrix remodelling mediated by intracellular digestion of collagen. The initial collagen-binding step of phagocytosis was examined in human gingival fibroblasts and Rat-2 fibroblasts. Cells were pretreated with Msp or vehicle, and binding of collagen-coated beads was measured by flow cytometry. Exposure to Msp induced a dose- and time-dependent decrease in cells that bound collagen beads; the inhibition of binding was reversed by absorption with anti-Msp antibodies. Msp-treated fibroblasts remained viable but underwent actin reorganization, including the assembly of a dense meshwork of subcortical actin filaments. Shear force assays showed that Msp abrogated collagen-binding interactions in the minimal affinity range required for stable adhesion. Fluorescence microscopy and immunoblotting showed equivalent amounts of beta1 integrin associated with collagen beads bound to Msp- and vehicle-treated cells. Photobleaching experiments found a similar percentage mobile fraction of beta1 integrins recovered in bleached areas of the plasma membrane. In contrast, Msp-induced inhibition of collagen binding was reversed by beta1 integrin affinity-activating antibodies and by latrunculin B, which prevented subcortical actin assembly. We conclude that native Msp of T. denticola inhibits the binding step of collagen phagocytosis in fibroblasts by inducing subcortical actin filament assembly and restricting affinity modulation of beta1 integrins. We suggest that, like Msp, bacterial toxins that target the cytoskeleton may also perturb the signalling networks required for cellular engagement of matrix ligands.