Olivier Huck

Periodontal diseases and stress: a brief review

Periodontal diseases are common chronic inflammatory diseases caused by pathogenic microorganisms colonising the subgingival area and inducing local and systemic elevations of pro-inflammatory cytokines resulting in tissue destruction. Apparition and evolution of periodontal diseases are influenced by many local or systemic risk factors. Psychological stress has been suggested as one of them and may negatively influence the outcome of periodontal treatment. However, mechanisms explaining the possible relationship between stress and increased susceptibility to periodontal disease remain poorly understood. Several stress markers are found in blood and saliva of patients with periodontal diseases and influence the development of periodontal diseases by several mechanisms including modifications of the inflammatory response and changes in the composition of the dental biofilm. The aim of this review is to provide an insight into the relationship between psychological stress and periodontal diseases.

Relationship between Periodontal Diseases and Preterm Birth: Recent Epidemiological and Biological Data

For ten years, the incidence of preterm birth does not decrease in developed countries despite the promotion of public health programs. Many risk factors have been identified including ethnicity, age, tobacco, and infection. However, almost 50% of preterm birth causes remain unknown. The periodontal diseases are highly prevalent inflammatory and infectious diseases of tooth supporting tissues leading to an oral disability. They influence negatively general health worsening cardiovascular diseases and diabetes. Periodontal diseases have been also suspected to increase the rate of preterm birth, but data remain contradictory. The objective of this review is to present the principal results of epidemiological, biological, and interventional studies on the link between periodontal diseases and preterm birth. The conclusions of this work underline the importance for the physician/obstetrician to identify women at risk for preterm birth and to address these patients to dentist for periodontal examination and treatment in order to limit adverse pregnancy outcomes.

Periodontal and Systemic Responses in Various Mice Models of Experimental Periodontitis: Respective Roles of Inflammation Duration and Porphyromonas gingivalis Infection

BACKGROUND The great variability of periodontal and systemic responses to experimental periodontitis reflects the inherent pathogenic complexity of mice models and could limit the resulting interpretations and their extension to human diseases. This study compared the effect of Porphyromonas gingivalis (Pg) infection and experimental periodontitis duration at local and systemic levels in various models. METHODS Periodontitis was induced in C57BL/6J mice by ligatures previously incubated with Pg (LIGPG group) or not (LIG group) or by oral gavage (GAV) with Pg ATCC 33277. Blood samples were taken, and mice were euthanized at different times. Periodontal tissue destruction, osteoclast number, and inflammation were assessed by histomorphometry, tartrate-resistant acid phosphatase histoenzymology, and cathepsin B (CATB) and matrix metalloproteinase 9 (MMP9) immunochemistry. Serum levels of interleukin-6 (IL-6) and IL-1β were measured using enzyme-linked immunosorbent assay bioplex methods. RESULTS Periodontal tissue destruction and osteoclast numbers were significantly elevated in LIGPG models compared to LIG and GAV models. They increased with time with the exception of osteoclast numbers in the LIG model. CATB and MMP9 expression was related to bone destruction processes and Pg infection. The highest serum levels of IL-6 and IL-1β were observed in the LIGPG group. A decrease of IL-6 and an increase of IL-1β serum level were observed with time in LIGPG group contrary to LIG group. CONCLUSIONS These data indicate that Pg infection worsened periodontal tissue destruction through specific pathogenic pathways and modified systemic response to periodontal inflammation. Furthermore, the blood cytokine response to ligature models showed their relevance for evaluating the systemic impact of periodontal disease.

Evaluating periodontal risk for patients at risk of or suffering from atherosclerosis: Recent biological hypotheses and therapeutic consequences

Cardiovascular disease, such as atherosclerosis, is the main cause of mortality in developed countries. Most atherosclerosis risk factors have been identified and are treated, improving patient cardiovascular status and reducing mortality, but some remain unknown. Periodontal disease is generally defined as inflammatory disease initiated by accumulation of dental bacterial plaque, leading to the destruction of tissues that support the teeth. Severe forms have a high prevalence (15% of the population) and are associated with the presence of virulent pathogens such as Porphyromonas gingivalis. Epidemiological studies have shown that severe periodontal disease negatively influences cardiovascular status. The aim of this paper was to present a synthesis of the most recent biological data related to the link between periodontal and cardiovascular disease. The potential biological mechanisms involved in these two inflammatory diseases (bacteriological theory, inflammatory theory, immune theory) were developed. According to the observed positive effects of periodontal treatment on systemic conditions, the benefit of a reinforced collaboration between dentists and cardiologists was discussed, especially for patients at risk for cardiovascular disease.

A living thick nanofibrous implant bifunctionalized with active growth factor and stem cells for bone regeneration.

New-generation implants focus on robust, durable, and rapid tissue regeneration to shorten recovery times and decrease risks of postoperative complications for patients. Herein, we describe a new-generation thick nanofibrous implant functionalized with active containers of growth factors and stem cells for regenerative nanomedicine. A thick electrospun poly(ε-caprolactone) nanofibrous implant (from 700 μm to 1 cm thick) was functionalized with chitosan and bone morphogenetic protein BMP-7 as growth factor using layer-by-layer technology, producing fish scale-like chitosan/BMP-7 nanoreservoirs. This extracellular matrix-mimicking scaffold enabled in vitro colonization and bone regeneration by human primary osteoblasts, as shown by expression of osteocalcin, osteopontin, and bone sialoprotein (BSPII), 21 days after seeding. In vivo implantation in mouse calvaria defects showed significantly more newly mineralized extracellular matrix in the functionalized implant compared to a bare scaffold after 30 days’ implantation, as shown by histological scanning electron microscopy/energy dispersive X-ray microscopy study and calcein injection. We have as well bifunctionalized our BMP-7 therapeutic implant by adding human mesenchymal stem cells (hMSCs). The activity of this BMP-7-functionalized implant was again further enhanced by the addition of hMSCs to the implant (living materials), in vivo, as demonstrated by the analysis of new bone formation and calcification after 30 days’ implantation in mice with calvaria defects. Therefore, implants functionalized with BMP-7 nanocontainers associated with hMSCs can act as an accelerator of in vivo bone mineralization and regeneration.

Cytokines during periodontal wound healing: potential application for new therapeutic approach.

Regeneration of periodontal tissues is one of the main goals of periodontal therapy. However, current treatment, including surgical approach, use of membrane to allow maturation of all periodontal tissues, or use of enamel matrix derivatives, presents limitations in their indications and outcomes leading to the development of new tissue engineering strategies. Several cytokines are considered as key molecules during periodontal destruction process. However, their role during each phase of periodontal wound healing remains unclear. Control and modulation of the inflammatory response and especially, release of cytokines or activation/inhibition in a time- and spatial-controlled manner may be a potential perspective for periodontal tissue engineering. The aim of this review was to summarize the specific role of several cytokines during periodontal wound healing and the potential therapeutic interest of inflammatory modulation for periodontal regeneration especially related to the expression sequence of cytokines.

Active implant combining human stem cell microtissues and growth factors for bone-regenerative nanomedicine

AIMS Mesenchymal stem cells (MSCs) from adult bone marrow provide an exciting and promising stem cell population for the repair of bone in skeletal diseases. Here, we describe a new generation of collagen nanofiber implant functionalized with growth factor BMP-7 nanoreservoirs and equipped with human MSC microtissues (MTs) for regenerative nanomedicine. MATERIALS & METHODS By using a 3D nanofibrous collagen membrane and by adding MTs rather than single cells, we optimize the microenvironment for cell colonization, differentiation and growth. RESULTS & CONCLUSION Furthermore, in this study, we have shown that by combining BMP-7 with these MSC MTs in this double 3D environment, we further accelerate bone growth in vivo. The strategy described here should enhance the efficiency of therapeutic implants compared with current simplistic approaches used in the clinic today based on collagen implants soaked in bone morphogenic proteins.

Association between periodontitis and arterial hypertension: A systematic review and meta-analysis

BACKGROUND Several studies have shown that periodontal diseases are associated with hypertension (HT). However, heterogeneity among populations, diagnosis criteria, and shared risk factors represent some difficulties in terms of interpretation. Therefore, the aim of this study was to determine the magnitude of the association between periodontal diseases and HT. METHODS AND RESULTS A systematic review and meta-analysis, including studies published up to June 2016, have been performed. Sixteen studies assessing the association between periodontal diseases and HT have been included. The meta-analysis considering all included studies (moderate to severe periodontitis) showed that the presence of HT was associated with the presence of periodontal diseases (OR, 1.50; 95% CI, 1.27-1.78). To reduce potential bias, a stratified analysis has been performed illustrating the impact of inclusion criteria and adjustments on the magnitude of the association. Interestingly, when only studies with secure diagnosis of severe periodontitis and HT were considered, an OR=1.64 (95% CI, 1.23-2.19) has been measured. CONCLUSIONS Periodontal diseases are associated with a higher risk of HT especially for severe periodontitis. However, no conclusions could be made regarding the causative involvement of periodontal diseases mainly due to the reduced number of available prospective studies and remaining questions regarding underlying biological mechanisms.

Porphyromonas gingivalis-impaired innate immune response via NLRP3 proteolysis in endothelial cells

Porphyromonas gingivalis (Pg) is involved in the link between periodontal diseases and atherosclerosis worsening. In periodontal cells, Pg modifies IL-1β expression via the NLRP3 inflammasome pathway activation. Our aim was to investigate NLRP3 inflammasome activation in endothelial cells (ECs) after Pg infection and Pg-LPS stimulation. In both situations, RT-PCR experiments demonstrated an increase of the NLRP3 mRNA level that can be potentiated by pre-treatment of ECs with 5 mM ATP. However, Western blotting analysis revealed that Pg infection induced a proteolysis of NLRP3 protein and a major decrease of the native protein. After ATP pre-treatment and/or Pg-LPS stimulation, this proteolysis was not observed, while NLRP3 protein levels were increased. Proteolysis of the NLRP3 protein was not observed with heat-killed Pg and inhibition of ECs protein synthesis with cycloheximide did not abolish the NLRP3 protein degradation induced by Pg infection in ATP pre-treated cells. Additionally, significant increases of secreted IL-1β were measured after ATP pre-treatment and/or Pg-LPS stimulation, but not after Pg infection. These data showed that Pg and Pg-LPS differentially controlled the NLRP3 inflammasome pathway in ECs, and suggested a novel potential mechanism developed by Pg to reduce IL-1β secretion and to escape host immune response.

Identification and Characterization of MicroRNA Differentially Expressed in Macrophages Exposed to Porphyromonas gingivalis Infection

ABSTRACT MicroRNAs (miRNAs) are short, noncoding RNAs involved in the regulation of several processes associated with inflammatory diseases and infection. Bacterial infection modulates miRNA expression to subvert any innate immune response. In this study we analyzed, using microarray analysis, the bacterial modulation of miRNAs in bone marrow-derived macrophages (BMMs) in which activity was induced by infection with Porphyromonas gingivalis. The expression of several miRNAs was modulated 3 h postinfection (at a multiplicity of infection of 25). A bioinformatic analysis was performed to further identify pathways related to the innate immune host response under the influence of selected miRNAs. To assess the effects of the miRNAs identified on cytokine secretion (tumor necrosis factor alpha [TNF-α] and interleukin-10 [IL-10]), BMMs were transfected with selected miRNA mimics and inhibitors. Transfection with mmu-miR-155 and mmu-miR-2137 did not modify TNF-α secretion, while their inhibitors increased it. Inhibitors of mmu-miR-2137 and mmu-miR-7674 increased the secretion of the anti-inflammatory factor IL-10. In P. gingivalis-infected BMMs, mmu-miR-155-5p significantly decreased TNF-α secretion while inhibitor of mmu-miR-2137 increased IL-10 secretion. In vivo, in a mouse model of P. gingivalis-induced calvarial bone resorption, injection of mmu-miR-155-5p or anti-mmu-miR-2137 reduced the size of the lesion significantly. Furthermore, anti-mmu-miR-2137 significantly reduced inflammatory cell infiltration, osteoclast activity, and bone loss. Bioinformatic analysis demonstrated that pathways related to cytokine- and chemokine-related pathways but also osteoclast differentiation may be involved in the effects observed. This study contributes further to our understanding of P. gingivalis-induced modulation of miRNAs and their physiological effects. It highlights the potential therapeutic merits of targeting mmu-miR-155-5p and mmu-miR-2137 to control inflammation induced by P. gingivalis infection.