Philippe Kémoun

Human dental follicle cells acquire cementoblast features under stimulation by BMP-2/-7 and enamel matrix derivatives (EMD) in vitro

The dental follicle (DF) surrounding the developing tooth germ is an ectomesenchymal tissue composed of various cell populations derived from the cranial neural crest. Human dental follicle cells (HDFC) are believed to contain precursor cells for cementoblasts, periodontal ligament cells, and osteoblasts. Bone morphogenetic proteins (BMPs) produced by Hertwig’s epithelial root sheath or present in enamel matrix derivatives (EMD) seem to be involved in the control of DF cell differentiation, but their precise function remains largely unknown. We report the immunolocalization of STRO-1 (a marker of multipotential mesenchymal progenitor cells) and BMP receptors (BMPR) in DF in vivo. In culture, HDFC co-express STRO-1/BMPR and exhibit multilineage properties. Incubation with rhBMP-2 and rhBMP-7 or EMD for 24xa0h increases the expression of BMP-2 and BMP-7 by HDFC. Long-term stimulation of these cells by rhBMP-2 and/or rhBMP-7 or EMD significantly increases alkaline phosphatase activity (AP) and mineralization. Expression of cementum attachment protein (CAP) and cementum protein-23 (CP-23), two putative cementoblast markers, has been detected in EMD-stimulated whole DF and in cultured HDFC stimulated with EMD or BMP-2 and BMP-7. RhNoggin, a BMP antagonist, abolishes AP activity, mineralization, and CAP/CP-23 expression in HDFC cultures and the expression of BMP-2 and BMP-7 induced by EMD. Phosphorylation of Smad-1 and MAPK is stimulated by EMD or rhBMP-2. However, rhNoggin blocks only Smad-1 phosphorylation under these conditions. Thus, EMD may activate HDFC toward the cementoblastic phenotype, an effect mainly (but not exclusively) involving both exogenous and endogenous BMP-dependent pathways.

High-Fat Diet Induces Periodontitis in Mice through Lipopolysaccharides (LPS) Receptor Signaling: Protective Action of Estrogens

Background A fat-enriched diet favors the development of gram negative bacteria in the intestine which is linked to the occurrence of type 2 diabetes (T2D). Interestingly, some pathogenic gram negative bacteria are commonly associated with the development of periodontitis which, like T2D, is characterized by a chronic low-grade inflammation. Moreover, estrogens have been shown to regulate glucose homeostasis via an LPS receptor dependent immune-modulation. In this study, we evaluated whether diet-induced metabolic disease would favor the development of periodontitis in mice. In addition, the regulatory role of estrogens in this process was assessed. Methods Four-week-old C57BL6/J WT and CD14 (part of the TLR-4 machinery for LPS-recognition) knock-out female mice were ovariectomised and subcutaneously implanted with pellets releasing either placebo or 17β-estradiol (E2). Mice were then fed with either a normal chow or a high-fat diet for four weeks. The development of diabetes was monitored by an intraperitoneal glucose-tolerance test and plasma insulin concentration while periodontitis was assessed by identification of pathogens, quantification of periodontal soft tissue inflammation and alveolar bone loss. Results The fat-enriched diet increased the prevalence of periodontal pathogenic microbiota like Fusobacterium nucleatum and Prevotella intermedia, gingival inflammation and alveolar bone loss. E2 treatment prevented this effect and CD14 knock-out mice resisted high-fat diet-induced periodontal defects. Conclusions/Significance Our data show that mice fed with a diabetogenic diet developed defects and microflora of tooth supporting-tissues typically associated with periodontitis. Moreover, our results suggest a causal link between the activation of the LPS pathway on innate immunity by periodontal microbiota and HFD-induced periodontitis, a pathophysiological mechanism that could be targeted by estrogens.

The role of cell surface markers and enamel matrix derivatives on human periodontal ligament mesenchymal progenitor responses in vitro.

Periodontitis is a chronic-, infectious-disease of the human periodontium that is characterized by the loss of supporting tissues surrounding the tooth such as the periodontal ligament (PDL), cementum and alveolar bone. Regeneration of the periodontium is dependent on the participation of mesenchymal stem/stromal cells (MSC) resident in the PDL. Enamel matrix derivative (EMD), an extract from immature porcine enamel rich in amelogenin protein but that also contain bone morphogenetic protein (BMP), is used to treat periodontal defects. The effects of EMD on MSC cells of the PDL are not well characterized. In this inxa0vitro study, we identify PDL progenitor cells from multiple individuals and demonstrate that EMD stimulates them. We show that the effect of EMD on cell proliferation and migration is mediated through the amelogenin it contains, while the differentiation of these progenitor cells to cell types of mineralized tissue is mainly due to BMP signaling.

Periodontitis induced by Porphyromonas gingivalis drives periodontal microbiota dysbiosis and insulin resistance via an impaired adaptive immune response

Objective To identify a causal mechanism responsible for the enhancement of insulin resistance and hyperglycaemia following periodontitis in mice fed a fat-enriched diet. Design We set-up a unique animal model of periodontitis in C57Bl/6 female mice by infecting the periodontal tissue with specific and alive pathogens like Porphyromonas gingivalis (Pg), Fusobacterium nucleatum and Prevotella intermedia. The mice were then fed with a diabetogenic/non-obesogenic fat-enriched diet for up to 3u2005months. Alveolar bone loss, periodontal microbiota dysbiosis and features of glucose metabolism were quantified. Eventually, adoptive transfer of cervical (regional) and systemic immune cells was performed to demonstrate the causal role of the cervical immune system. Results Periodontitis induced a periodontal microbiota dysbiosis without mainly affecting gut microbiota. The disease concomitantly impacted on the regional and systemic immune response impairing glucose metabolism. The transfer of cervical lymph-node cells from infected mice to naive recipients guarded against periodontitis-aggravated metabolic disease. A treatment with inactivated Pg prior to the periodontal infection induced specific antibodies against Pg and protected the mouse from periodontitis-induced dysmetabolism. Finally, a 1-month subcutaneous chronic infusion of low rates of lipopolysaccharides from Pg mimicked the impact of periodontitis on immune and metabolic parameters. Conclusions We identified that insulin resistance in the high-fat fed mouse is enhanced by pathogen-induced periodontitis. This is caused by an adaptive immune response specifically directed against pathogens and associated with a periodontal dysbiosis.

Concise Review: Mesenchymal Stromal Cells Used for Periodontal Regeneration: A Systematic Review

Periodontitis is a chronic infectious disease of the soft and hard tissues supporting the teeth. Recent advances in regenerative medicine and stem cell biology have paved the way for periodontal tissue engineering. Mesenchymal stromal cells (MSCs) delivered in situ to periodontal defects may exert their effects at multiple levels, including neovascularization, immunomodulation, and tissue regeneration. This systematic review had two goals: (a) to objectively quantify key elements for efficacy and safety of MSCs used for periodontal regeneration and (b) to identify patterns in the existing literature to explain differences between studies and suggest recommendations for future research. This systematic review provided good evidence of the capacity of MSCs to regenerate periodontal tissues in animals; however, experimentally generated defects used in animal studies do not sufficiently mimic the pathophysiology of periodontitis in humans. Moreover, the safety of such interventions in humans still needs to be studied. There were marked differences between experimental and control groups that may be influenced by characteristics that are crucial to address before translation to human clinical trials. We suggest that the appropriate combination of cell source, carrier type, and biomolecules, as well as the inclusion of critical path issues for a given clinical case, should be further explored and refined before transitioning to clinical trials. Future studies should investigate periodontal regenerative procedures in animal models, including rodents, in which the defects generated are designed to more accurately reflect the inflammatory status of the host and the shift in their pathogenic microflora.

Effect of periodontal treatment on the clinical parameters of patients with rheumatoid arthritis: study protocol of the randomized, controlled ESPERA trial

BackgroundRheumatoid 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/designThe 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.DiscussionEvidence-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 registrationThe ESPERA Trial was registered in Current Controlled Trials [ISRCTN79186420] on 2012/03/20. The trial started recruiting on 2012/03/06.

Cold Atmospheric Plasma Induces a Predominantly Necrotic Cell Death via the Microenvironment

Introduction Cold plasma is a partially ionized gas generated by an electric field at atmospheric pressure that was initially used in medicine for decontamination and sterilization of inert surfaces. There is currently growing interest in using cold plasma for more direct medical applications, mainly due to the possibility of tuning it to obtain selective biological effects in absence of toxicity for surrounding normal tissues,. While the therapeutic potential of cold plasma in chronic wound, blood coagulation, and cancer treatment is beginning to be documented, information on plasma/cell interaction is so far limited and controversial. Methods and Results Using normal primary human fibroblast cultures isolated from oral tissue, we sought to decipher the effects on cell behavior of a proprietary cold plasma device generating guided ionization waves carried by helium. In this model, cold plasma treatment induces a predominantly necrotic cell death. Interestingly, death is not triggered by a direct interaction of the cold plasma with cells, but rather via a transient modification in the microenvironment. We show that modification of the microenvironment redox status suppresses treatment toxicity and protects cells from death. Moreover, necrosis is not accidental and seems to be an active response to an environmental cue, as its execution can be inhibited to rescue cells. Conclusion These observations will need to be taken into account when studying in vitro plasma/cell interaction and may have implications for the design and future evaluation of the efficacy and safety of this new treatment strategy.

Clinical research activity in periodontal medicine: a systematic mapping of trial registers.

AIMnThe primary aim of the study was to systematically map registration records on periodontal medicine in clinical trial registers. The secondary aim was to assess the evolution of periodontal medicine in clinical periodontal research as a whole.nnnMATERIAL AND METHODSnWe searched all registration records related to periodontology in the World Health Organization International Clinical Trials Registry Platform. For registration records classified in the field of periodontal medicine, we assigned the 2015 MeSH(®) term for the most precisely corresponding systemic condition.nnnRESULTSnFifty-seven systemic conditions have been hypothesized to be linked with periodontal diseases, covering nearly 2% of the diseases indexed in MeSH. In addition to diabetes, cardiovascular disease or preterm birth, other systemic conditions have been the subject of registration records, such as anaemia, liver diseases, dyspepsia or ankylosing spondylitis. A trend towards increasing diversification of systemic conditions has appeared over time. About a third of registration records in clinical periodontal research deals with periodontal medicine.nnnCONCLUSIONSnPeriodontal medicine now constitutes an important part of clinical periodontal research. Research activity in periodontal medicine has grown continuously since the early 2000s, and exploration of registers gives a useful up-to-date snapshot of this constantly evolving field of research.

Cell therapy of periodontium: from animal to human?

Periodontitis is a chronic inflammatory disease affecting the soft and hard tissues supporting the teeth, which often leads to tooth loss. Its significant impact on the patients general health and quality of life point to a need for more effective management of this condition. Existing treatments include scaling/root planning and surgical approaches but their overall effects are relatively modest and restricted in application. The goal of regenerative therapy of periodontal defects is to enhance endogenous progenitors and thus promote optimal wound healing. Considering that the host or tissue might be defective in the periodontitis context, it has been proposed that grafting exogenous stem cells would produce new tissues and create a suitable microenvironment for tissue regeneration. Thus, cell therapy of periodontium has been assessed in many animal models and promising results have been reported. However, the methodological diversity of these studies makes the conversion to clinical practice difficult. The aim of this review is to highlight the primary requirements to be satisfied before the leap to clinical trials can be made. We therefore review cell therapy applications for periodontal regeneration in animal models and the concerns to be addressed before undertaking human experiments.