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1.  Is immunesenescence a contributing factor for periodontal diseases? 
Current concept in periodontal diseases (PDs) states that it is the host's response toward the periodontal pathogens which leads to tissue destruction and attachment loss. Hence the role of immune response in the progression and resolution of PD must be considered vital. Any alteration in the immune system disturbs the homeostasis of the periodontium. Decline in immune system is the hallmark of aging, leading to increased susceptibility of elderly individuals to bacterial infections. The periodontal apparatus which is being constantly exposed to plaque biofilm is more vulnerable to destruction in aged individuals. Ageing related alterations in immune system has been discussed elsewhere as a contributor to various chronic inflammatory diseases like atherosclerosis, preterm, and low birth weight, etc. This paper reviews on the possible role of aging in periodontal destruction through altered immunity. Aging has long been associated with altered systemic inflammation. It has been discussed whether (1) this systemic inflammation is a consequence of increased occurrence of chronic inflammatory diseases upon aging or (2) aging associated systemic inflammation leads to such diseases. The immune responses which are protective at the first stages of life might result detrimental in the elderly. Hence it might be very difficult to individuate genetic profiles that might allow to identify individuals with a major risk for one or more age related diseases. Taking this into consideration, the cause of PDs in elderly is addressed with a systemic approach in order to understand the complex interplay between the aging immunity and PDs.
doi:10.4103/0972-124X.113064
PMCID: PMC3713746  PMID: 23869121
Aging; immunesenescence; immunity; inflammaging; periodontal diseases
2.  Inflammation and Uncoupling as Mechanisms of Periodontal Bone Loss 
Journal of Dental Research  2011;90(2):143-153.
Periodontal disease is characterized by both inflammation and bone loss. Advances in research in both these areas have led to a new appreciation of not only each field but also the intimate relationship between inflammation and bone loss. This relationship has resulted in a new field of science called osteoimmunology and provides a context for better understanding the pathogenesis of periodontal disease. In this review, we discuss several aspects of the immuno-inflammatory host response that ultimately results in loss of alveolar bone. A proposal is made that periodontal inflammation not only stimulates osteoclastogenesis but also interferes with the uncoupling of bone formation and bone resorption, consistent with a pathologic process. Furthermore, arguments based on experimental animal models suggest a critical role of the spatial and temporal aspects of inflammation in the periodontium. A review of these findings leads to a new paradigm to help explain more fully the impact of inflammation on alveolar bone in periodontal disease so that it includes the effects of inflammation on uncoupling of bone formation from resorption.
doi:10.1177/0022034510385236
PMCID: PMC3144100  PMID: 21135192
adaptive immunity; bone matrix; cytokine; innate immunity; IL-1; osteoblast; osteoclast; RANK ligand; TNF
3.  Elevation of white blood cells and platelet counts in patients having chronic periodontitis 
The Saudi Dental Journal  2011;24(1):17-21.
Background and aim
Many risk factors that might contribute to the pathogenesis of atherosclerosis have been proposed, including chronic inflammation and infection. Furthermore, systemic inflammatory responses to periodontal bacteria have been suggested as a pathogenetic link between periodontal disease and atherosclerosis. The purpose of this study was to estimate the white blood cell (WBC) and platelet counts in chronic periodontitis patients.
Materials and methods
Fifty patients with chronic periodontitis and 50 patients with healthy periodontium were included in this study. Oral hygiene status, pocket probing depth (PPD) and clinical attachment level (CAL) were measured. During clinical evaluation, venous blood samples were taken to analyze the WBC and platelet counts. Statistical analysis was utilized to compare differences across groups.
Results
Periodontitis patients demonstrated a significantly higher WBC count (7.22 ± 1.42 × 109 cells/L) than that of control patients (5.64 ± 1.56 × 109 cells/L; P < 0.001). The platelet count of patients with chronic periodontitis (290.73 ± 56.56 × 109 cells/L) was also significantly higher compared to the healthy group (223.37 ± 50.27 × 109 cells/L; P < 0.001).
Conclusion
Levels of WBCs and platelets are elevated in periodontitis patients compared to healthy controls.
doi:10.1016/j.sdentj.2011.10.006
PMCID: PMC3723072  PMID: 23960523
WBC; RBC; Systematic disease; Thrombocyte; Periodontitis; Coronary heart disease; Oral conditions
4.  Rheumatoid arthritis is an autoimmune disease caused by periodontal pathogens 
A statistically significant association between periodontal disease (PD) and systemic diseases has been identified. Rheumatoid arthritis (RA), which is a chronic inflammatory joint disease, exhibits similar characteristics and pathogenesis to PD. The association between RA and PD has been investigated, and numerous publications on this subject exist. Approximately 20 bacterial species have been identified as periodontal pathogens, and these organisms are linked to various types of PD. The most analyzed species of periodontopathic bacteria are Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, and Aggregatibacter actinomycetemcomitans. Antibodies and DNA from these oral pathogens have been isolated from the sera and synovial fluids of RA patients. This rapid communication describes the role of periodontal pathogens in the etiopathogenesis of RA.
doi:10.2147/IJGM.S45929
PMCID: PMC3668087  PMID: 23737674
etiopathogenesis; chronic arthritis; periodontitis; Porphyromonas gingivalis; systemic disease; animal models; antibiotics
5.  Functional human T-cell immunity and osteoprotegerin ligand control alveolar bone destruction in periodontal infection  
Periodontitis, a prime cause of tooth loss in humans, is implicated in the increased risk of systemic diseases such as heart failure, stroke, and bacterial pneumonia. The mechanisms by which periodontitis and antibacterial immunity lead to alveolar bone and tooth loss are poorly understood. To study the human immune response to specific periodontal infections, we transplanted human peripheral blood lymphocytes (HuPBLs) from periodontitis patients into NOD/SCID mice. Oral challenge of HuPBL-NOD/SCID mice with Actinobacillus actinomycetemcomitans, a well-known Gram-negative anaerobic microorganism that causes human periodontitis, activates human CD4+ T cells in the periodontium and triggers local alveolar bone destruction. Human CD4+ T cells, but not CD8+ T cells or B cells, are identified as essential mediators of alveolar bone destruction. Stimulation of CD4+ T cells by A. actinomycetemcomitans induces production of osteoprotegerin ligand (OPG-L), a key modulator of osteoclastogenesis and osteoclast activation. In vivo inhibition of OPG-L function with the decoy receptor OPG diminishes alveolar bone destruction and reduces the number of periodontal osteoclasts after microbial challenge. These data imply that the molecular explanation for alveolar bone destruction observed in periodontal infections is mediated by microorganism-triggered induction of OPG-L expression on CD4+ T cells and the consequent activation of osteoclasts. Inhibition of OPG-L may thus have therapeutic value to prevent alveolar bone and/or tooth loss in human periodontitis.
This article may have been published online in advance of the print edition. The date of publication is available from the JCI website, http://www.jci.org. J. Clin. Invest. 106:R59–R67 (2000).
PMCID: PMC3102542  PMID: 10995794
6.  Expression levels of novel cytokine IL-32 in periodontitis and its role in the suppression of IL-8 production by human gingival fibroblasts stimulated with Porphyromonas gingivalis  
Journal of Oral Microbiology  2012;4:10.3402/jom.v4i0.14832.
Background
IL-32 was recently found to be elevated in the tissue of rheumatoid arthritis and inflammatory bowel disease. Periodontitis is a chronic inflammatory disease caused by polymicrobial infections that result in soft tissue destruction and alveolar bone loss. Although IL-32 is also thought to be associated with periodontal disease, its expression and possible role in periodontal tissue remain unclear. Therefore, this study investigated the expression patterns of IL-32 in healthy and periodontally diseased gingival tissue. The expression of IL-32 in cultured human gingival fibroblasts (HGF) as well as effects of autocrine IL-32 on IL-8 production from HGF were also examined.
Methods
Periodontal tissue was collected from both healthy volunteers and periodontitis patients, and immunofluorescent staining was performed in order to determine the production of IL-32. Using real-time PCR and ELISA, mRNA expression and protein production of IL-32 in HGF, stimulated by Porphyromonas gingivalis (Pg), were also investigated.
Results
Contrary to our expectation, the production of IL-32 in the periodontitis patients was significantly lower than in the healthy volunteers. According to immunofluorescent microscopy, positive staining for IL-32 was detected in prickle and basal cell layers in the epithelium as well as fibroblastic cells in connective tissue. Addition of fixed Pg in vitro was found to suppress the otherwise constitutive expression of IL-32 mRNA and protein in HGF. However, recombinant IL-32 in vitro inhibited the expression of IL-8 mRNA by HGF stimulated with Pg. Interestingly, anti-IL-32 neutralizing antibody upregulated the IL-8 mRNA expression in non-stimulated HGF, indicating that constitutive expression of IL-32 in HGF suppressed IL-8 mRNA expression in the absence of bacterial stimulation.
Conclusion
These results indicate that IL-32 is constitutively produced by HGF which can be suppressed by Pg and may play a role in the downregulation of inflammatory responses, such as IL-8 production, in periodontal tissue.
doi:10.3402/jom.v4i0.14832
PMCID: PMC3307671  PMID: 22435084
Interleukin-32; periodontal disease; Porphyromonas gingivalis; human gingival fibroblast; Interleukin-8
7.  Is there a relationship between periodontitis and rheumatoid arthritis? 
Background:
Growth of scientific evidence suggests an exquisite association between oral infection and systemic diseases. Though etiologies of periodontitis and rheumatoid arthritis (RA) are separate, their underlying pathological processes are sufficient to warrant consideration of hypothesis that individuals at risk of developing RA may also be at the risk of developing periodontitis and vice versa.
Materials and Methods:
To test their relationship, a study was carried out on 80 individuals. Part A: Forty subjects having rheumatoid arthritis (RA group) were compared to 40 controls without arthritis (NRA group). Their periodontal indices rheumatoid arthritis clinical laboratory parameters were also correlated with periodontitis in group. Part B: Omplete periodontal treatment was done for 10 patients of group suffering from periodontitis. All parameters of periodontal indices were measured pre-operatively and weeks after completion of periodontal treatment.
Results:
(1) There was high prevalence of mild (12.5%) to moderate (75%) periodontitis in group. (2) Extent severity of periodontal disease rheumatoid arthritis were positively correlated. (3) Statistically significant differences were present in periodontal parameters of RA group compared to NRA group. (4) There was statistically, significant reduction in parameters postoperatively with concomitant decrease in periodontal parameters in RA group.
Conclusion:
Thus, an association exists between periodontal disease with an underlying dysregulation of the molecular pathways in the inflammatory response. Also, there are significant management implications in the future as new host modifying medications are developed.
doi:10.4103/0972-124X.94599
PMCID: PMC3357028  PMID: 22628958
Inflammation; periodontitis; relationship; rheumatoid arthritis
8.  Links demystified: Periodontitis and cancer 
Dental Research Journal  2013;10(6):704-712.
Cancer is marked by the uncontrolled growth of cells, tissue invasion and metastasis to various organs via the circulatory and lymphatic systems. Recent data have expanded the concept that inflammation is a critical component of tumor progression. Many cancers arise from sites of infection, chronic irritation, and inflammation. The tumor microenvironment, which is largely orchestrated by inflammatory cells, is an indispensable participant in the neoplastic process, fostering proliferation, survival, and migration. Periodontal disease, a chronic inflammatory condition is characterized by an oral bacterial infection leading to inflammation within the supporting tissues of the teeth, which often leads to the destruction of the periodontal tissues and alveolar bone that support the teeth. This oral inflammation often has systemic effects leading to an increased concentration of circulating inflammatory markers with the severity of disease being correlated directly with levels of serum inflammatory markers. Periodontal infection has been linked to organ and systemic diseases. There is documented evidence of significant associations between cancer of the lung, kidney, pancreas, hematological and oral cancers, and periodontal disease. This articles reviews and summarizes the possible biological mechanisms involved between periodontal infection and cancer.
PMCID: PMC3872619  PMID: 24379856
Cancer; periodontitis; plausible mechanisms
9.  Systemic Diseases Caused by Oral Infection 
Clinical Microbiology Reviews  2000;13(4):547-558.
Recently, it has been recognized that oral infection, especially periodontitis, may affect the course and pathogenesis of a number of systemic diseases, such as cardiovascular disease, bacterial pneumonia, diabetes mellitus, and low birth weight. The purpose of this review is to evaluate the current status of oral infections, especially periodontitis, as a causal factor for systemic diseases. Three mechanisms or pathways linking oral infections to secondary systemic effects have been proposed: (i) metastatic spread of infection from the oral cavity as a result of transient bacteremia, (ii) metastatic injury from the effects of circulating oral microbial toxins, and (iii) metastatic inflammation caused by immunological injury induced by oral microorganisms. Periodontitis as a major oral infection may affect the host's susceptibility to systemic disease in three ways: by shared risk factors; subgingival biofilms acting as reservoirs of gram-negative bacteria; and the periodontium acting as a reservoir of inflammatory mediators. Proposed evidence and mechanisms of the above odontogenic systemic diseases are given.
PMCID: PMC88948  PMID: 11023956
10.  Diabetes and periodontal disease 
Journal of Pharmacy & Bioallied Sciences  2012;4(Suppl 2):S280-S282.
Diabetes mellitus is a systemic disease characterized by increased blood glucose levels and abnormalities of lipid metabolism due to absence or decreased level of insulin. It affects all the body organs and their functions either directly or indirectly. Every dentist should have a basic understanding of the etiopathogenesis, oral and systemic manifestations of this disease. The periodontal diseases are a consequence of extension of the gingival inflammation into the underlying supporting structures of the periodontium, initiated by the presence of plaque and its products on the surfaces of the teeth and the adjoining structures. The progression of periodontal disease is influenced by variety of factors like microorganisms, host response, systemic background, and genetic makeup of the host. Amongst them, diabetes mellitus tops the list. Diabetes and periodontitis influence the clinical outcome of each other and control of both influences the clinical improvement of each.
doi:10.4103/0975-7406.100251
PMCID: PMC3467897  PMID: 23066270
Diabetes mellitus; periodontitis; vascular changes
11.  The Relationship Between Periodontal Disease (Pd) and Cardiovascular Disease (Cvd). 
The recent focus on the potential link between periodontal and cardiovascular disease (PD and CVD) is part of the larger renewed interest on the role of infection and inflammation in the etiology of atherosclerosis and its clinical manifestations. Periodontal Disease is an inflammatory process affecting the periodontium, the tissue that surrounds and supports the teeth. The process usually starts with an inflammatory process of the gum (gingivitis) but it may progress with an extensive involvement of the gum, as well as the periodontal ligament and the bone surrounding the teeth resulting in substantial bone loss. Periodontal disease is a common oral pathological condition in the adult age and represents the leading cause of tooth loss. PD prevalence increases with age and there are estimates that up to 49,000,000 Americans may suffer from some form of gum disease. The gingival plaque associated with PD is colonized by a number of gram-positive and gram-negative bacteria that have been shown to affect the initiation and development of PD and have been associated with the potential etiological role of PD in CVD and other chronic conditions. A potential etiological link between PD and CVD may have important public health implications as both the exposure (PD) and the outcomes (CVD) are highly prevalent in industrialized societies. In situations in which both the exposure and the outcome are highly prevalent even modest associations, like those observed in the studies reporting on the link between PD and CVD outcomes, may have relevance. There are not definite data on the effect of periodontal treatment on CVD clinical outcomes (either in primary or secondary prevention) however it should be pointed out that the limited (both in terms of numbers and study design) experimental evidence in humans suggests a possible beneficial effect of periodontal treatment of indices of functional and structural vascular health.
doi:10.4084/MJHID.2010.030
PMCID: PMC3033151  PMID: 21415980
12.  MECHANISMS INVOLVED IN THE ASSOCIATION BETWEEN PERIDONTAL DISEASES AND CARDIOVASCULAR DISEASE 
Oral Diseases  2011;17(5):450-461.
It is now well accepted that besides the cholesterol associated mechanisms of atherogenesis, inflammation plays a crucial role in all stages of the development of the atherosclerotic lesion. This “inflammation hypothesis” raises the possibility that, through systemic elevations of pro-inflammatory cytokines, periodontal diseases might also contribute to systemic inflammation and, therefore, to atherogenesis. In fact, there is evidence that periodontal diseases are associated with higher systemic levels of high-sensitivity C-reactive protein and a low grade systemic inflammation. This phenomenon has been explained based on mechanisms associated with either the infectious or the inflammatory nature of periodontal diseases. The purposes of this article are to review (1) the evidence suggesting a role for oral bacterial species, particularly periodontal pathogens, in atherogenesis; (2) the potential mechanisms explaining an etiological role for oral bacteria in atherosclerosis; (3) the evidence suggesting that periodontal infections are accompanied by a heightened state of systemic inflammation; (4) the potential sources of systemic inflammatory biomarkers associated with periodontal diseases; and (5) the effects of periodontal therapy on systemic inflammatory biomarkers and cardiovascular risk.
doi:10.1111/j.1601-0825.2010.01784.x
PMCID: PMC3373016  PMID: 21223455
Cardiovascular disease; atherosclerosis; periodontal diseases; infection; periodontal pathogens; bacteremia; inflammatory response; systemic biomarkers; C-reactive protein
13.  Effect of anti-rheumatic agents on periodontal parameters and biomarkers of inflammation: a systematic review and meta-analysis 
Purpose
Anti-rheumatic agents target common molecular pathways of inflammation in rheumatoid arthritis (RA) and periodontitis. The purpose of this study was to determine the relative effect of anti-rheumatic agents on the levels of inflammatory biomarkers and periodontal inflammation in RA patients with periodontitis.
Methods
A systematic review and meta-analysis were conducted of studies comparing periodontal parameters of inflammation, such as bleeding on probing, and biomarkers of inflammation in RA patients with periodontitis and healthy adults with and without periodontitis. The search included the electronic databases MEDLINE, Cochrane Database of Systematic Reviews, and Google Scholar, inclusive through October 2011, with no language restrictions. Hand searches were conducted of the bibliographies of related journals and systematic reviews. Observational and interventional studies assessing the effects of antirheumatic therapy qualified for inclusion. Two reviewers performed independent data extraction and risk-of-bias assessment. Of the 187 identified publications, 13 studies fulfilled the inclusion criteria.
Results
When compared to healthy adults without periodontitis, RA subjects were found to have significantly higher levels of bleeding on probing and limited evidence of higher levels of interleukin-1β and tumor necrosis factor-α (TNF-α) in gingival crevicular fluid and saliva. No consistent differences were found in periodontal parameters and inflammatory biomarkers between RA subjects and adults with periodontitis. Studies evaluating the effect of anti-TNF-α therapy in RA subjects with periodontitis have yielded inconsistent results.
Conclusions
There are limited data, however, to suggest that anti-TNF-α agents can reduce local production of inflammatory cytokines and periodontal inflammation in RA patients with periodontitis.
doi:10.5051/jpis.2012.42.1.3
PMCID: PMC3296933  PMID: 22413068
Periodontitis; Rheumatoid arthritis; Tumor necrosis factor-alpha
14.  Complement and Periodontitis 
Biochemical pharmacology  2010;80(12):1992-2001.
Although the complement system is centrally involved in host defense, its overactivation or deregulation (e.g., due to inherent host genetic defects or due to pathogen subversion) may excessively amplify inflammation and contribute to immunopathology. Periodontitis is an oral infection-driven chronic inflammatory disease which exerts a systemic impact on health. This paper reviews evidence linking complement to periodontal inflammation and pathogenesis. Clinical and histological observations show a correlation between periodontal inflammatory activity and local complement activation. Certain genetic polymorphisms or deficiencies in specific complement components appear to predispose to increased susceptibility to periodontitis. Animal model studies and in vitro experiments indicate that periodontal bacteria can either inhibit or activate distinct components of the complement cascade. Porphyromonas gingivalis, a keystone species in periodontitis, subverts complement receptor 3 and C5a anaphylatoxin receptor signaling in ways that promote its adaptive fitness in the presence of non-productive inflammation. Overall, available evidence suggests that complement activation or subversion contributes to periodontal pathogenesis, although not all complement pathways or functions are necessarily destructive. Effective complement-targeted therapeutic intervention in periodontitis would require determining the precise roles of the various inductive or effector complement pathways. This information is essential as it may reveal which specific pathways need to be blocked to counteract microbial evasion and inflammatory pathology or, conversely, be enhanced to promote host immunity.
doi:10.1016/j.bcp.2010.06.017
PMCID: PMC2955993  PMID: 20599785
15.  Periodontal inflammation and bone loss in aged mice 
Journal of periodontal research  2010;45(4):574-578.
Background and objective
Young mice do not develop measurable periodontal bone loss, unless heavily infected with human periodontal pathogens. However, mice with genetically altered immune system are unable to control their own oral flora and develop periodontitis early in life. Based on the potential of the indigenous oral microbiota to cause periodontitis, we hypothesized that normal mice may ultimately develop inflammatory periodontal bone loss, i.e., as a function of age. If confirmed, this could serve as an aging model of chronic periodontitis.
Materials and methods
Periodontal bone levels were measured as the distance from the cementoenamel junction (CEJ) to the alveolar bone crest (ABC), in young (8-10 weeks of age), old (≥ 18 months of age), and mice of intermediate ages. Differential expression of inflammatory mediators in the gingivae of young and old mice was determined by quantitative real-time PCR.
Results
In comparison to young mice, old mice displayed significantly (p < 0.05) increased periodontal bone loss, accompanied by elevated expression of proinflammatory cytokines (interleukin-1β, tumor necrosis factor-α, and interleukin-17A) and innate immune receptors involved in the induction or amplification of inflammation (Toll-like receptor 2, CD14, CD11b, CD18, complement C5a receptor, and triggering receptor expressed on myeloid cells-3).
Conclusion
Mice develop naturally-induced periodontal bone loss as a function of age. This aging model of periodontitis represents a genuinely chronic model to study mechanisms of periodontal tissue destruction.
doi:10.1111/j.1600-0765.2009.01245.x
PMCID: PMC2894296  PMID: 20337897
Animal model; Alveolar bone; Chronic periodontitis; Inflammation; Innate immunology
16.  The Management of Inflammation in Periodontal Disease 
Journal of periodontology  2008;79(8 Suppl):1601-1608.
It has become clear in recent years that periodontitis is an inflammatory disease initiated by oral microbial biofilm. This distinction implies that it is the host response to the biofilm that destroys the periodontium in the pathogenesis of the disease. As our understanding of pathways of inflammation has matured, a better understanding of the molecular basis of resolution of inflammation has emerged. Resolution of inflammation is an active, agonist-mediated, well-orchestrated return of tissue homeostasis. There is an important distinction between anti-inflammation and resolution; anti-inflammation is pharmacologic intervention in inflammatory pathways, whereas resolution is biologic pathways restoring homeostasis. A growing body of research suggests that chronic inflammatory periodontal disease involves a failure of resolution pathways to restore homeostasis. This article reviews the resolution of inflammation in the context of periodontal disease and the potential for the modification of resolution pathways for the prevention and treatment of periodontal diseases. Proof-of-concept studies in the 1980s demonstrated that pharmacologic anti-inflammation prevented and slowed the progression of periodontal diseases in animals and man. However, the side-effect profile of such therapies precluded the use of non-steroidal anti-inflammatory drugs or other enzyme inhibitors or receptor antagonists in periodontal therapy. The isolation and characterization of resolving agonist molecules has opened a new area of research using endogenous lipid mediators of resolution as potential therapeutic agents for the management of inflammatory periodontitis. Work in animal models of periodontitis has revealed the potential of this therapeutic approach for its prevention and treatment and forced the reconsideration of our understanding of the pathogenesis of human periodontal diseases.
doi:10.1902/jop.2008.080173
PMCID: PMC2563957  PMID: 18673016
Anti-inflammatory; lipoxins; Porphyromonas gingivalis; periodontal disease; resolvin E1
17.  Direct Recognition of Fusobacterium nucleatum by the NK Cell Natural Cytotoxicity Receptor NKp46 Aggravates Periodontal Disease 
PLoS Pathogens  2012;8(3):e1002601.
Periodontitis is a common human chronic inflammatory disease that results in the destruction of the tooth attachment apparatus and tooth loss. Although infections with periopathogenic bacteria such as Porphyromonas gingivalis (P. gingivalis) and Fusobacterium nucleatum (F. nucleatum) are essential for inducing periodontitis, the nature and magnitude of the disease is determined by the host's immune response. Here, we investigate the role played by the NK killer receptor NKp46 (NCR1 in mice), in the pathogenesis of periodontitis. Using an oral infection periodontitis model we demonstrate that following F. nucleatum infection no alveolar bone loss is observed in mice deficient for NCR1 expression, whereas around 20% bone loss is observed in wild type mice and in mice infected with P. gingivalis. By using subcutaneous chambers inoculated with F. nucleatum we demonstrate that immune cells, including NK cells, rapidly accumulate in the chambers and that this leads to a fast and transient, NCR1-dependant TNF-α secretion. We further show that both the mouse NCR1 and the human NKp46 bind directly to F. nucleatum and we demonstrate that this binding is sensitive to heat, to proteinase K and to pronase treatments. Finally, we show in vitro that the interaction of NK cells with F. nucleatum leads to an NCR1-dependent secretion of TNF-α. Thus, the present study provides the first evidence that NCR1 and NKp46 directly recognize a periodontal pathogen and that this interaction influences the outcome of F. nucleatum-mediated periodontitis.
Author Summary
Periodontal disease is a common bacterial-induced inflammatory process in which F. nucleatum and P. gingivalis infections lead to the destruction of the teeth supporting attachment apparatus. Previous reports demonstrated that immune cells aggravate the severity of the disease. However, whether NK cells in general and NKp46 (a major killer receptor expressed by NK cells) in particular, play a protective or destructive role in this disease is unknown. Using mice deficient in NCR1 (the mouse orthlogue of NKp46), we demonstrate that oral infection of mice with F. nucleatum, but not with P. gingivalis results in an NCR1-dependent alveolar bone loss. In addition, we show that F. nucleatum is recognized by NCR1 and NKp46 directly and that this recognition leads to the secretion of TNF-α, a central cytokine critically involved in the pathogenesis of periodontal destruction. Collectively, we show that NCR1 and NKp46 play a critical role in the pathogenesis of F. nucleatum-mediated periodontitis.
doi:10.1371/journal.ppat.1002601
PMCID: PMC3310798  PMID: 22457623
18.  MAPK Usage in Periodontal Disease Progression 
Journal of Signal Transduction  2012;2012:308943.
In periodontal disease, host recognition of bacterial constituents, including lipopolysaccharide (LPS), induces p38 MAPK activation and subsequent inflammatory cytokine expression, favoring osteoclastogenesis and increased net bone resorption in the local periodontal environment. In this paper, we discuss evidence that the p38/MAPK-activated protein kinase-2 (MK2) signaling axis is needed for periodontal disease progression: an orally administered p38α inhibitor reduced the progression of experimental periodontal bone loss by reducing inflammation and cytokine expression. Subsequently, the significance of p38 signaling was confirmed with RNA interference to attenuate MK2-reduced cytokine expression and LPS-induced alveolar bone loss. MAPK phosphatase-1 (MKP-1), a negative regulator of MAPK activation, was also critical for periodontal disease progression. In MPK-1-deficient mice, p38-sustained activation increased osteoclast formation and bone loss, whereas MKP-1 overexpression dampened p38 signaling and subsequent cytokine expression. Finally, overexpression of the p38/MK2 target RNA-binding tristetraprolin (TTP) decreased mRNA stability of key inflammatory cytokines at the posttranscriptional level, thereby protecting against periodontal inflammation. Collectively, these studies highlight the importance of p38 MAPK signaling in immune cytokine production and periodontal disease progression.
doi:10.1155/2012/308943
PMCID: PMC3270463  PMID: 22315682
19.  Smoking and Periodontal Disease 
Materia Socio-Medica  2012;24(4):274-276.
Periodontitis is a group of inflammatory diseases affecting the supporting tissues of the tooth (periodontium). The periodontium consists of four tissues : gingiva, alveolar bone and periodontal ligaments. Tobbaco use is one of the modifiable risk factors and has enormous influance on the development, progres and tretmen results of periodontal disease. The relationship between smoking and periodontal health was investigated as early as the miiddle of last century. Smoking is an independent risk factor for the initiation, extent and severity of periodontal disease. Additionally, smoking can lower the chances for successful tretment. Tretmans in patients with periodontal disease must be focused on understanding the relationship between genetic and environmental factors. Only with individual approach we can identify our pacients risks and achieve better results.
doi:10.5455/msm.2012.24.274-276
PMCID: PMC3633395  PMID: 23678331
smoking; periodontal disease.
20.  Effect of periodontal treatment on the clinical parameters of patients with rheumatoid arthritis: study protocol of the randomized, controlled ESPERA trial 
Trials  2013;14:253.
Background
Rheumatoid arthritis (RA) is a chronic inflammatory disorder that leads to joint damage, deformity, and pain. It affects approximately 1% of adults in developed countries. Periodontitis is a chronic oral infection, caused by inflammatory reactions to gram-negative anaerobic bacteria, and affecting about 35 to 50% of adults. If left untreated, periodontitis can lead to tooth loss. A significant association has been shown to exist between periodontitis and RA in observational studies. Some intervention studies have suggested that periodontal treatment can reduce serum inflammatory biomarkers such as C-reactive protein, or erythrocyte sedimentation rate. We hypothesize that periodontitis could be an aggravating factor in patients with RA, and that its treatment would improve RA outcomes. The aim of this clinical trial is to assess the effect of periodontal treatment on the biological and clinical parameters of patients with RA.
Methods/design
The ESPERA (Experimental Study of Periodontitis and Rheumatoid Arthritis) study is an open-label, randomized, controlled trial. Subjects with both RA and periodontitis will be recruited at two university hospitals in southwestern France. In total, 40 subjects will be randomized into two arms (intervention and control groups), and will be followed up for 3 months. Intervention will consist of full-mouth supra-gingival and sub-gingival non-surgical scaling and root planing, followed by systemic antibiotic therapy, local antiseptics, and oral hygiene instructions. After the 3-month follow-up period, the same intervention will be applied to the subjects randomized to the control group.
The primary outcome will be change of in Disease Activity Score in 28 Joints (DAS28) at the end of the follow-up period. Secondary outcomes will be the percentages of subjects with 20%, 50%, and 70% improvement in disease according to the American College of Rheumatology criteria. Health-related quality of life assessments (the Health Assessment Questionnaire and the Geriatric Oral Health Assessment Index) will also be compared between the two groups.
Discussion
Evidence-based management of potential aggravating factors in subjects with active RA could be of clinical importance, yet there are few randomized controlled trials on the effect of periodontal treatment on the clinical parameters of RA. The ESPERA trial is designed to determine if non-surgical periodontal treatment could improve clinical outcomes in patients with active RA, and the quality of life of these patients.
Trial registration
The ESPERA Trial was registered in Current Controlled Trials [ISRCTN79186420] on 2012/03/20. The trial started recruiting on 2012/03/06.
doi:10.1186/1745-6215-14-253
PMCID: PMC3751435  PMID: 23945051
Rheumatoid arthritis; Periodontal diseases; Periodontitis; Randomized controlled trial; Protocol
21.  Periodontal infection in adult-onset Still’s disease patient: clinical and haematological considerations 
BMJ Case Reports  2011;2011:bcr0220113803.
In this case report, the authors described the first case of a patient with adult-onset Still’s disease (AOSD) who presents advanced periodontal infection. AOSD is a rare systemic inflammatory disorder of unknown aetiology, characterised by spiking fever, usually exceeding 39°C, an evanescent salmon pink rash, arthritis and multiorgan involvement. Periodontal infection is a pathogen-induced oral inflammatory disease affecting the supporting tissues of teeth and is currently considered as a risk factor for cardiovascular disease. Several cytokines capable of inducing systemic effects are produced during the course of this infection and the values of serum markers of inflammation, such as C reactive protein (CRP), may significantly decrease after periodontal treatment. Although AOSD can produce elevations in CRP, similar increase may be produced by periodontal infection, suggesting the need for medical and dental diagnosis when evaluating the sources of acute-phase responses in systemic autoimmune disease patients.
doi:10.1136/bcr.02.2011.3803
PMCID: PMC3083007  PMID: 22696669
22.  Treatment modalities and evaluation models for periodontitis 
Periodontitis is the most common localized dental inflammatory disease related with several pathological conditions like inflammation of gums (gingivitis), degeneration of periodontal ligament, dental cementum and alveolar bone loss. In this perspective, the various preventive and treatment modalities, including oral hygiene, gingival irrigations, mechanical instrumentation, full mouth disinfection, host modulation and antimicrobial therapy, which are used either as adjunctive treatments or as stand-alone therapies in the non-surgical management of periodontal infections, have been discussed. Intra-pocket, sustained release systems have emerged as a novel paradigm for the future research. In this article, special consideration is given to different locally delivered anti-microbial and anti inflammatory medications which are either commercially available or are currently under consideration for Food and Drug Administration (FDA) approval. The various in vitro dissolution models and microbiological strain investigated to impersonate the infected and inflamed periodontal cavity and to predict the in vivo performance of treatment modalities have also been thrashed out. Animal models that have been employed to explore the pathology at the different stages of periodontitis and to evaluate its treatment modalities are enlightened in this proposed review.
doi:10.4103/2230-973X.104394
PMCID: PMC3555006  PMID: 23373002
Chemotherapeutic agents; intra-pocket devices; mechanical therapies; oral hygiene
23.  Critical analysis of biomarkers in the current periodontal practice 
Periodontal disease is a chronic microbial infection that triggers inflammation-mediated loss of the periodontal ligament and alveolar bone that supports the teeth. Because of the increasing prevalence and associated comorbidities, there is a need for the development of new diagnostic tests that can detect the presence of active disease, predict future disease progression, and evaluate the response to periodontal therapy, thereby improving the clinical management of periodontal patients. The diagnosis of active phases of periodontal disease and the identification of patients at risk for active disease represent challenges for clinical investigators and practitioners. Advances in diagnostic research are moving toward methods whereby the periodontal risk can be identified and quantified by objective measures using biomarkers. Patients with periodontitis may have elevated circulating levels of specific inflammatory markers that can be correlated to the severity of the disease. Advances in the use of oral fluids as possible biological samples for objective measures of the current disease state, treatment monitoring, and prognostic indicators have boosted saliva- and other oral-based fluids to the forefront of technology. Gingival crevicular fluid (GCF) is an inflammatory exudate that can be collected at the gingival margin or within the gingival crevice. This article highlights recent advances in the use of biomarker-based disease diagnostics that focus on the identification of active periodontal disease from plaque biofilms, GCF, and saliva.
doi:10.4103/0972-124X.84376
PMCID: PMC3183658  PMID: 21976831
Biomarkers; C-telopeptide pyridinoline; gingival crevicular fluid; periodontal disease
24.  Pathogen-induced inflammation at sites distant from oral infection: bacterial persistence and induction of cell-specific innate immune inflammatory pathways 
Molecular oral microbiology  2010;25(5):305-316.
SUMMARY
A hallmark of infection with the gram-negative pathogen Porphyromonas gingivalis is the induction of a chronic inflammatory response. P. gingivalis induces a local chronic inflammatory response that results in oral inflammatory bone destruction, which manifests as periodontal disease. In addition to chronic inflammation at the initial site of infection, mounting evidence has accumulated supporting a role for P. gingivalis-mediated periodontal disease as a risk factor for several systemic diseases including, diabetes, preterm birth, stroke, and atherosclerotic cardiovascular disease. A growing number of in vitro studies have demonstrated that P. gingivalis infection stimulates cell activation commensurate with expected responses paralleling inflammatory atherosclerotic-type responses. Furthermore, various mouse models have been used to examine the ability of P. gingivalis to stimulate chronic inflammatory plaque accumulation and recent studies have pointed to a pivotal role for innate immune signaling via the Toll-like receptors in the chronic inflammation associated with P. gingivalis infection. In this review we discuss the pathogen and host cell specificity of these responses and discuss possible mechanisms by which this oral pathogen can induce and maintain a chronic state of inflammation at sites distant from oral infection.
doi:10.1111/j.2041-1014.2010.00582.x
PMCID: PMC2951292  PMID: 20883220
atherosclerosis; bacterial persistence; immune evasion; innate immunity; Porphyromonas gingivalis; Toll-like receptor
25.  Destructive effects of smoking on molecular and genetic factors of periodontal disease 
Many epidemiological evidences have proven the association between smoking and periodontal disease. The causality can be further established by linking findings of traditional epidemiological studies with the developments in molecular techniques that occurred in the last decade. The present article reviews recent studies that address the effect of smoking on molecular and genetic factors in periodontal disease. Most findings support the fact that tobacco smoking modulates destruction of the periodontium through different pathways: microcirculatory and host immune systems, connective tissue, and bone metabolism. Although smokers experience an increased burden of inflammatory responses to microbial challenges compared to non-smokers, understanding the association between smoking and periodontal diseases involves substantial problems with respect to accuracy of measurements, and particularly, sampling of many subjects. It remains unclear whether genetic susceptibility to periodontal disease is influenced by exposure to smoking or the effect of smoking on periodontal disease is influenced by genetic susceptibility. Employment of molecular techniques may play a key role in further elucidation of mechanisms linking smoking and periodontal destruction, the direct relationship as environmental factors and indirect relationship through genetic factors.
doi:10.1186/1617-9625-8-4
PMCID: PMC2836317  PMID: 20170537

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