Ligature-induced periodontitis induces systemic inflammation but does not alter acute outcome after stroke in mice

Galectin-3 inhibition alleviated LPS-induced periodontal inflammation in gingival fibroblasts and experimental periodontitis mice

OBJECTIVES

Clinical studies have confirmed that galectin-3 (Gal-3) levels are significantly elevated in periodontitis patients. The present study aimed to explore the effects of Gal-3 inhibition on periodontal inflammation in vitro and in vivo.

METHODS

Human gingival fibroblasts (HGFs) with or without Gal-3 knockdown were stimulated by lipopolysaccharide (LPS), and a ligation-induced mouse periodontitis model treated with a Gal-3 inhibitor was established. Hematoxylin-eosin (H&E) and immunohistochemistry (IHC) staining were used to evaluate Gal-3 levels in gingival tissues. Quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to detect Gal-3, interleukin (IL)-6, IL-8, and C-C motif ligand 2 (CCL2) expression. Immunofluorescence and western blotting were used to detect NF-κB and ERK signaling pathway activation. Micro-computed tomography was used to analyse the degree of bone loss.

RESULTS

Gal-3 was significantly up-regulated in inflamed gingival tissues and LPS-induced HGFs. Gal-3 knockdown markedly decreased LPS-induced IL-6, IL-8, and CCL2 expression and blocked NF-κB and ERK signaling pathway activation in HGFs. In the mouse periodontitis model, Gal-3 inhibition significantly alleviated IL-1β and IL-6 infiltration in gingival tissue and mitigated periodontal bone loss.

CONCLUSIONS

Gal-3 inhibition notably alleviated periodontal inflammation partly through blocking NF-κB and ERK signaling pathway activation.

The effect of stroke on the bone mineral density: A systematic review and meta-analysis

OBJECTIVES

Stroke survivors frequently encounter physical complications. This study aimed to evaluate the impact of stroke on bone mineral density (BMD) and assess the risk of post-stroke osteoporosis or osteoporotic fractures.

DESIGN

Systematic review and meta-analysis.

SETTING AND PARTICIPANTS

We systematically searched Medline, Embase, and the Cochrane Database of Systematic Reviews to identify longitudinal studies reporting the influence of stroke on BMD, osteoporosis, and osteoporotic fractures. Pooled analyses were performed utilizing random-effects models.

RESULTS

This study included 21 studies with 1,029,742 participants. The mean difference of BMD in the paretic femoral neck between follow-up and initial measurements was -0.07 g/cm2 (95% CI, -0.09 to -0.04), and -0.03 g/cm2 (95% CI, -0.05 to -0.01) in the non-paretic femoral neck. A follow-up length exceeding six months was associated with a more pronounced decrease compared to a follow-up of under six months (MD, -0.08; 95% CI, -0.11 to -0.05 vs MD, -0.04; 95% CI, -0.06 to -0.02; P =  0.03). No significant change in lumbar spine BMD was detected post-stroke (MD, -0.00; 95% CI, -0.03 to 0.02), nor was significant change observed in the non-paretic distal radius, proximal humerus, tibia, trochanter, and total hip. Stroke was not associated with an increased risk of osteoporosis or osteoporotic fractures (HR, 1.43; 95% CI, 0.95-2.13).

CONCLUSION

Stroke survivors undergo significant BMD loss in paralyzed limbs, most notably in the femoral neck. However, BMD in the lumbar spine does not exhibit a significant decrease post-stroke. The risk of post-stroke osteoporosis or osteoporotic fractures should be interpreted with caution and needs further investigation.

Neutrophils' Contribution to Periodontitis and Periodontitis-Associated Cardiovascular Diseases

Neutrophils represent the primary defense against microbial threats playing a pivotal role in maintaining tissue homeostasis. This review examines the multifaceted involvement of neutrophils in periodontitis, a chronic inflammatory condition affecting the supporting structures of teeth summarizing the contribution of neutrophil dysfunction in periodontitis and periodontal-related comorbidities. Periodontitis, a pathological condition promoted by dysbiosis of the oral microbiota, is characterized by the chronic inflammation of the gingiva and subsequent tissue destruction. Neutrophils are among the first immune cells recruited to the site of infection, releasing antimicrobial peptides, enzymes, and reactive oxygen species to eliminate pathogens. The persistent inflammatory state in periodontitis can lead to aberrant neutrophil activation and a sustained release of proinflammatory mediators, finally resulting in tissue damage, bone resorption, and disease progression. Growing evidence now points to the correlation between periodontitis and systemic comorbidities. Indeed, the release of inflammatory mediators, immune complexes, and oxidative stress by neutrophils, bridge the gap between local and systemic immunity, thus highlighting neutrophils as key players in linking periodontal inflammation to chronic conditions, including cardiovascular diseases, diabetes mellitus, and rheumatoid arthritis. This review underscores the crucial role of neutrophils in the pathogenesis of periodontitis and the complex link between neutrophil dysfunction, local inflammation, and systemic comorbidities. A comprehensive understanding of neutrophil contribution to periodontitis development and their impact on periodontal comorbidities holds significant implications for the management of oral health. Furthermore, it highlights the need for the development of novel approaches aimed at limiting the persistent recruitment and activation of neutrophils, also reducing the impact of periodontal inflammation on broader health contexts, offering promising avenues for improved disease management and patient care.

Systemic antibiotics increase microbiota pathogenicity and oral bone loss

Periodontitis is the most widespread oral disease and is closely related to the oral microbiota. The oral microbiota is adversely affected by some pharmacologic treatments. Systemic antibiotics are widely used for infectious diseases but can lead to gut dysbiosis, causing negative effects on the human body. Whether systemic antibiotic-induced gut dysbiosis can affect the oral microbiota or even periodontitis has not yet been addressed. In this research, mice were exposed to drinking water containing a cocktail of four antibiotics to explore how systemic antibiotics affect microbiota pathogenicity and oral bone loss. The results demonstrated, for the first time, that gut dysbiosis caused by long-term use of antibiotics can disturb the oral microbiota and aggravate periodontitis. Moreover, the expression of cytokines related to Th17 was increased while transcription factors and cytokines related to Treg were decreased in the periodontal tissue. Fecal microbiota transplantation with normal mice feces restored the gut microbiota and barrier, decreased the pathogenicity of the oral microbiota, reversed the Th17/Treg imbalance in periodontal tissue, and alleviated alveolar bone loss. This study highlights the potential adverse effects of long-term systemic antibiotics-induced gut dysbiosis on the oral microbiota and periodontitis. A Th17/Treg imbalance might be related to this relationship. Importantly, these results reveal that the periodontal condition of patients should be assessed regularly when using systemic antibiotics in clinical practice.

The Influence of Periodontal Diseases and the Stimulation of Saliva Secretion on the Course of the Acute Phase of Ischemic Stroke

Background and purpose: The course of an ischemic stroke depends on many factors. The influence of periodontal diseases and the stimulation of salivation on the course and severity of stroke remains unresolved. Therefore, the aim of the study was to analyze the severity of ischemic stroke depending on the occurrence of periodontal diseases and saliva stimulation. Methods: The severity of the neurological condition was assessed using the NIHSS scale on days one, three and seven of stroke. The incidence of periodontal diseases was classified using the Hall’s scale in the first day of stroke. On days one and seven of stroke, the concentration of IL-1β, MMP-8, OPG and RANKL in the patients’ saliva was assessed using the Elisa technique. At the same time, the level of CRP and the number of leukocytes in the peripheral blood were tested on days one, three and seven of the stroke, and the incidence of upper respiratory and urinary tract infections was assessed. Results:100 consecutive patients with their first ever ischemic stroke were enrolled in the study. 56 randomly selected patients were subjected to the stimulation of salivation, the remaining patients were not stimulated. In the study of the severity of the neurological condition using the NIHS scale on days three and seven of stroke, the degree of deficit in patients without periodontal disease significantly improved compared to patients with periodontal disease, respectively (p < 0.01 and p = 0.01). Patients from the stimulated group had more severe neurological deficit at baseline (p = 0.04). On days three and seven of neurological follow-up, the condition of patients from both groups improved with a further distinct advantage of the unstimulated group over the stimulated group, respectively (p = 0.03 and p < 0.001). In patients from both groups, a statistically significant decrease in CRP and lymphocyte levels was observed on day seven in relation to day one. Conclusions: The occurrence of periodontal disease in a patient with stroke affects the severity of stroke. Stimulation of the mouth and salivary glands in these patients may have a positive effect on the course of stroke, taking into account the dynamics of neurological symptoms.

Local induction of regulatory T cells prevents inflammatory bone loss in ligature-induced experimental periodontitis in mice

Periodontitis (periodontal disease) is a highly prevalent disease, affecting over 65 million adults in the United States alone. Characterized by an overburden of invasive bacteria, gum inflammation and plaque buildup, over time, these symptoms can result in severe loss of gingival tissue attachment, bone resorption and even tooth loss. Although current treatments (local antibiotics and scaling and root planing procedures) target the bacterial dysbiosis, they do not address the underlying inflammatory imbalance in the periodontium. In the healthy steady state, the body naturally combats destructive, imbalanced inflammatory responses through regulatory pathways mediated by cells such as regulatory T cells (Tregs). Consequently, we hypothesized that local enrichment of regulatory lymphocytes (Tregs) could restore local, immunological homeostasis and prevent the main outcome of bone loss. Accordingly, we locally delivered a combination of TGFβ, Rapamycin, and IL2 microspheres in a ligature-induced murine periodontitis model. Herein, we have demonstrated this preventative treatment decreases alveolar bone loss, increases the local ratio of Tregs to T effector cells and changes the local microenvironment’s expression of inflammatory and regenerative markers. Ultimately, these Treg-inducing microspheres appear promising as a method to improve periodontitis outcomes and may be able to serve as a platform delivery system to treat other inflammatory diseases.

Periodontopathic Microbiota and Atherosclerosis: Roles of TLR-Mediated Inflammation Response

Atherosclerosis is a chronic inflammatory disease with a high prevalence worldwide, contributing to a series of adverse cardiovascular and cerebrovascular diseases. Periodontal disease induced by pathogenic periodontal microbiota has been well established as an independent factor of atherosclerosis. Periodontal microorganisms have been detected in atherosclerotic plaques. The high-risk microbiota dwelling in the subgingival pocket can stimulate local and systematic host immune responses and inflammatory cascade reactions through various signaling pathways, resulting in the development and progression of atherosclerosis. One often-discussed pathway is the Toll-like receptor-nuclear factor-κB (TLR-NF-κB) signaling pathway that plays a central role in the transduction of inflammatory mediators and the release of proinflammatory cytokines. This narrative review is aimed at summarizing and updating the latest literature on the association between periodontopathic microbiota and atherosclerosis and providing possible therapeutic ideas for clinicians regarding atherosclerosis prevention and treatment.

Obesity influences the proteome of periodontal ligament tissues following periodontitis induction in rats

BACKGROUND AND OBJECTIVES

Many studies have been conducted to better understand the molecular mechanism involved with periodontitis progression. There has been growing interest in the potential impact of obesity on periodontitis onset and progression, but the mechanisms involved remain to be elucidated. The present study was designed to determine the impact of obesity on experimentally induced periodontitis in rats and identify novel pathways involved.

METHODS

Sixteen Holtzman rats were distributed into two groups (n = 8): ligature-induced periodontitis (P) and obesity plus ligature-induced periodontitis (OP). Obesity was induced by a high-fat diet for 70 days, whereas periodontitis was induced for 20 days, with a cotton thread placed around the upper first molars bilaterally. Alveolar bone loss was measured by microtomographic analysis and histologically by histometry on the hemimaxillae. The protein composition of the periodontal ligament was evaluated by proteomic analysis.

RESULTS

Data analysis (body weight, adipose tissue weight, and blood test) confirmed obesity induction, whereas bone loss was confirmed by micro-CT and histologic analyses. Proteome analysis from the periodontal ligament tissues (PDL) identified 819 proteins, 53 exclusive to the P group, 28 exclusive to the OP group, and 738 commonly expressed. Validation was performed by immunohistochemistry for selected proteins (spondin1, vinculin, and TRAP).

CONCLUSION

Histologically, it was found that obesity did not significantly affect bone loss resulting from periodontitis. However, the present study's findings indicated that obesity affects the proteome of PDL submitted to experimental periodontitis, allowing for identifying potential targets for personalized approaches.

Stem Cell Therapy in Chronic Periodontitis: Host Limitations and Strategies

The treatment of chronic periodontitis is undergoing a transition from simple plaque removal and replacement with substitute materials to regenerative therapy, in which stem cells play an important role. Although stem cell-based periodontal reconstruction has been widely explored, few clinical regeneration studies have been reported. The inflammatory lesions under the impact of host factors such as local microbial–host responses, may impede the regenerative properties of stem cells and destroy their living microenvironment. Furthermore, systemic diseases, in particular diabetes mellitus, synergistically shape the disordered host-bacterial responses and exacerbate the dysfunction of resident periodontal ligament stem cells (PDLSCs), which ultimately restrain the capacity of mesenchymal stromal cells (MSCs) to repair the damaged periodontal tissue. Accordingly, precise regulation of an instructive niche has become a promising approach to facilitate stem cell-based therapeutics for ameliorating periodontitis and for periodontal tissue regeneration. This review describes host limitations and coping strategies that influence resident or transplanted stem cell-mediated periodontal regeneration, such as the management of local microbial–host responses and rejuvenation of endogenous PDLSCs. More importantly, we recommend that active treatments for systemic diseases would also assist in recovering the limited stem cell function on the basis of amelioration of the inflammatory periodontal microenvironment.

Novel Insight into the Mechanisms of the Bidirectional Relationship between Diabetes and Periodontitis

Periodontitis and diabetes are two major global health problems despite their prevalence being significantly underreported and underestimated. Both epidemiological and intervention studies show a bidirectional relationship between periodontitis and diabetes. The hypothesis of a potential causal link between the two diseases is corroborated by recent studies in experimental animals that identified mechanisms whereby periodontitis and diabetes can adversely affect each other. Herein, we will review clinical data on the existence of a two-way relationship between periodontitis and diabetes and discuss possible mechanistic interactions in both directions, focusing in particular on new data highlighting the importance of the host response. Moreover, we will address the hypothesis that trained immunity may represent the unifying mechanism explaining the intertwined association between diabetes and periodontitis. Achieving a better mechanistic insight on clustering of infectious, inflammatory, and metabolic diseases may provide new therapeutic options to reduce the risk of diabetes and diabetes-associated comorbidities.

Distribution of neutrophil and monocyte/macrophage populations induced by the CXCR4 inhibitor AMD3100 in blood and periodontal tissue early after periodontitis induction

CXCR4, a CXCL12 receptor, is expressed on epithelial cells, fibroblasts, and inflammatory cells. The CXCR4-CXCL12 interaction is related to the migration of neutrophils and monocytes/macrophages. Periodontitis, an inflammatory disease mainly caused by gram-negative bacteria, is characterized by infiltration of circulating inflammatory cells and alveolar bone (AB) loss. To investigate whether CXCR4 is involved in the distribution of neutrophils and monocytes/macrophages early after periodontitis induction, we examined the effects of AMD3100 (AMD), a CXCR4 antagonist, in ligature-induced periodontitis mice and LPS-injected air pouch mice. The periodontitis study was accomplished in control (C), periodontitis (P), and P + AMD groups. Periodontitis was induced by ligation of the mandibular first molar. AMD was intraperitoneally administered daily beginning the day before ligation until sacrifice on the third day after ligation. The air pouch study was accomplished in C, lipopolysaccharide (LPS), and LPS + AMD groups. Air pouches on mice backs were formed by subcutaneous injection of sterilized air. AMD was administered and then LPS was injected into the air pouch. For the detection of neutrophils and monocytes/macrophages in blood and air pouch exudates, flow cytometry was performed with anti-Ly6G/anti-CD11b antibodies (Abs) and anti-CD115 Ab, respectively. In periodontal tissue, Ly6G⁺ cells and CD115⁺ cells were counted by immunohistological analysis. AB loss was estimated by the periodontal ligament area in the furcation. In the periodontitis study, the P group showed higher numbers of Ly6G⁺ cells and CD115⁺ cells in blood and periodontal tissue than the C group. The P + AMD group showed a greater number of Ly6G⁺ cells and CD115⁺ cells in blood, but not in periodontal tissue compared to the P group. There was no difference in AB loss between the P and P + AMD groups. In the air pouch study, the LPS group had higher levels of Ly6G⁺ CD11b⁺ cells and CD115⁺ cells in both blood and exudates than the C group. The number of these cells in the LPS + AMD group was higher in blood than in the LPS group, but not in the exudates. The CXCR4 antagonist further increased neutrophil and monocyte/macrophage populations in the blood, but did not alter the levels in the periodontal tissue and exudates in mice with periodontitis and LPS-injected air pouches. These results suggest that during inflammatory conditions such as periodontitis, CXCR4 is involved in the distribution of neutrophils and monocytes/macrophages in the blood, but not in inflamed peripheral tissues.

Application of Ligature-Induced Periodontitis in Mice to Explore the Molecular Mechanism of Periodontal Disease

Periodontitis is an inflammatory disease characterized by the destruction of the periodontium. In the last decade, a new murine model of periodontitis has been widely used to simulate alveolar bone resorption and periodontal soft tissue destruction by ligation. Typically, 3-0 to 9-0 silks are selected for ligation around the molars in mice, and significant bone loss and inflammatory infiltration are observed within a week. The ligature-maintained period can vary according to specific aims. We reviewed the findings on the interaction of systemic diseases with periodontitis, periodontal tissue destruction, the immunological and bacteriological responses, and new treatments. In these studies, the activation of osteoclasts, upregulation of pro-inflammatory factors, and excessive immune response have been considered as major factors in periodontal disruption. Multiple genes identified in periodontal tissues partly reflect the complexity of the pathogenesis of periodontitis. The effects of novel treatment methods on periodontitis have also been evaluated in a ligature-induced periodontitis model in mice. This model cannot completely represent all aspects of periodontitis in humans but is considered an effective method for the exploration of its mechanisms. Through this review, we aimed to provide evidence and enlightenment for future studies planning to use this model.

Local and systemic mechanisms linking periodontal disease and inflammatory comorbidities

Periodontitis, a major inflammatory disease of the oral mucosa, is epidemiologically associated with other chronic inflammation-driven disorders, including cardio-metabolic, neurodegenerative and autoimmune diseases and cancer. Emerging evidence from interventional studies indicates that local treatment of periodontitis ameliorates surrogate markers of comorbid conditions. The potential causal link between periodontitis and its comorbidities is further strengthened by recent experimental animal studies establishing biologically plausible and clinically consistent mechanisms whereby periodontitis could initiate or aggravate a comorbid condition. This multi-faceted ‘mechanistic causality’ aspect of the link between periodontitis and comorbidities is the focus of this Review. Understanding how certain extra-oral pathologies are affected by disseminated periodontal pathogens and periodontitis-associated systemic inflammation, including adaptation of bone marrow haematopoietic progenitors, may provide new therapeutic options to reduce the risk of periodontitis-associated comorbidities.

Periodontitis has been causally linked to the development of other chronic inflammatory diseases outside the oral mucosa. In this Review, George Hajishengallis and Triantafyllos Chavakis consider the molecular basis of these links.

Neuroinflammation changes with periodontal inflammation status during periodontitis in wild-type mice

OBJECTIVE

To investigate neuroinflammation under different periodontal status.

MATERIALS AND METHODS

Experimental periodontitis was induced by molar ligation (Lig group) or periodontal injection of lipopolysaccharide (LPS, Lps group). Periodontal status was assessed by alveolar bone resorption and periodontal inflammation. Micro-computed tomography and haematoxylin-eosin staining were performed to assess alveolar bone resorption and periodontal inflammation, respectively. Neuroinflammation was assessed by glial cell proliferation and proinflammatory factor expression. Microgliosis was determined by immunofluorescence. Astrogliosis was determined by immunohistochemistry. Expressions of tumour necrosis factor-alpha (TNF-α) and interleukin (IL)-1β were assessed by enzyme-linked immunosorbent assay.

RESULTS

Microgliosis and astrogliosis in the Lig group were notable with molar ligation for 2 weeks and 4 weeks (p < .05), but were only slightly different similar from the control group by week 12. Microgliosis and astrogliosis in the Lps group were significant with LPS injection for 4 and 8 weeks (p < .05). The groups displayed a positive correlation between the degree of periodontal inflammation and the number of glial cells (p < .05). Expressions of IL-1β and TNF-α in the Lps group were significantly increased with LPS injection for 8 weeks (p < .05). In the Lig group, only TNF-α was highly expressed with molar ligation for 12 weeks (p < .05).

CONCLUSION

Both models demonstrated that the inflammatory response in the hippocampus of mice can change during periodontitis depending on the periodontal inflammation status.

Serum IgG titers to periodontal pathogens predict 3-month outcome in ischemic stroke patients

Several cohort studies have shown that periodontal disease is associated with an increased risk for stroke. However, it remains unclear whether serum antibody titers for a specific periodontal pathogen are associated with outcome after ischemic stroke, and which kinds of pathogens are associated with ischemic stroke. We examined the relationship between serum IgG titers to periodontal pathogens and outcome in ischemic stroke patients. A total of 445 patients with acute ischemic stroke (194 female [44.0%], mean age 71.9±12.3 years) were registered in this study. Serum IgG titers to 9 periodontal pathogens (Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Prevotella intermedia, Prevotella nigrescens, Fusobacterium nucleatum, Treponema denticola, Tannerella forsythensis, Campylobacter rectus, Eikenella corrodens) were evaluated using the enzyme-linked immunosorbent assay (ELISA) method. An unfavorable outcome was defined as a 3 or higher on the modified Rankin Scale. The proportion of patients with unfavorable outcome was 25.4% (113 patients). Based on multivariate logistic regression analysis, numbers of IgG antibodies positive for periodontal pathogens (odds ratio 1.20, 95% CI 1.02-1.41, p = 0.03) were independent predictors of unfavorable outcome in ischemic stroke patients.

Disequilibrium of Plasma Protease/Anti-Protease Due to Severe Periodontal Disease Contributes to Human Subarachnoid Hemorrhage

BACKGROUND

The pathophysiology of subarachnoid hemorrhages (SAHs) due to ruptured intracranial aneurysms (IAs) remains unclear. Although a relationship between SAHs and periodontal disease (PD) has been suggested, the mechanism requires clarification.

OBJECTIVE

To evaluate the relationship between PD and SAHs and to identify periodontal pathogens associated with SAHs.

METHODS

This prospective study included consecutive patients with ruptured (n = 11) and unruptured (n = 14) IAs and healthy controls (n = 8). The plasma and plaque subgingival bacterial deoxyribonucleic acid (DNA) levels in PD were evaluated by a dentist using the Community Periodontal Index of Treatment Needs (CPITN). Plasma levels of matrix metalloproteinase (MMP-9), tissue inhibitors of matrix metalloproteinase (TIMP2), and procollagen I were analyzed.

RESULTS

Patients with ruptured IAs, had significantly higher CPITN scores than the controls, suggesting that ruptured IAs were associated with severe PD. Although no rupture-specific bacteria were identified, the positive rate of plaque subgingival bacterial DNA was significantly higher in patients with severe PD than in those without severe PD. Multivariate logistic regression analysis indicated that bleeding on probing (BOP) was associated with ruptured IAs (odds ratio, 1.10; 95% confidence interval 1.04–1.20; P = .0001). BOP was positively associated with plasma MMP-9 levels and a disequilibrium in the MMP-9/TIMP2 ratio. BOP was negatively correlated with plasma procollagen I levels (P &lt; .05, for each). This suggested that local inflammation with severe PD might have systemic effects and lead to ruptured IAs.

CONCLUSION

Disequilibrium of plasma protease/anti-protease associated with a high BOP rate in severe PD may be attributable to IA rupture.

Polymicrobial periodontal disease triggers a wide radius of effect and unique virome

Periodontal disease is a microbially-mediated inflammatory disease of tooth-supporting tissues that leads to bone and tissue loss around teeth. Although bacterially-mediated mechanisms of alveolar bone destruction have been widely studied, the effects of a polymicrobial infection on the periodontal ligament and microbiome/virome have not been well explored. Therefore, the current investigation introduced a new mouse model of periodontal disease to examine the effects of a polymicrobial infection on periodontal ligament (PDL) properties, changes in bone loss, the host immune response, and the microbiome/virome using shotgun sequencing. Periodontal pathogens, namely Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Fusobacterium nucleatum were used as the polymicrobial oral inoculum in BALB/cByJ mice. The polymicrobial infection triggered significant alveolar bone loss, a heightened antibody response, an elevated cytokine immune response, a significant shift in viral diversity and virome composition, and a widening of the PDL space; the latter two findings have not been previously reported in periodontal disease models. Changes in the PDL space were present at sites far away from the site of insult, indicating that the polymicrobial radius of effect extends beyond the bone loss areas and site of initial infection and wider than previously appreciated. Associations were found between bone loss, specific viral and bacterial species, immune genes, and PDL space changes. These findings may have significant implications for the pathogenesis of periodontal disease and biomechanical properties of the periodontium. This new polymicrobial mouse model of periodontal disease in a common mouse strain is useful for evaluating the features of periodontal disease.

Distal Consequences of Oral Inflammation

Periodontitis is an incredibly prevalent chronic inflammatory disease, which results in the destruction of tooth supporting structures. However, in addition to causing tooth and alveolar bone loss, this oral inflammatory disease has been shown to contribute to disease states and inflammatory pathology at sites distant from the oral cavity. Epidemiological and experimental studies have linked periodontitis to the development and/or exacerbation of a plethora of other chronic diseases ranging from rheumatoid arthritis to Alzheimer's disease. Such studies highlight how the inflammatory status of the oral cavity can have a profound impact on systemic health. In this review we discuss the disease states impacted by periodontitis and explore potential mechanisms whereby oral inflammation could promote loss of homeostasis at distant sites.