Nikola Angelov

Porphyromonas gingivalis promotes Th17 inducing pathways in chronic periodontitis.

In periodontitis, a common chronic inflammatory condition, gram-negative-rich bacterial biofilms trigger, in susceptible individuals, perpetuating inflammation that results in extensive tissue damage of tooth supporting structures. To delineate immune cell-dependent mechanisms whereby bacterial challenge drives persistent destructive inflammation in periodontitis and other inflammatory diseases, we studied involved tissues ex vivo and investigated host cell responses to the periodontal pathogen Porphyromonas gingivalis, in vitro. Diseased lesions were populated by abundant Th17 cells, linked to infection, chronic inflammation/autoimmunity and tissue pathology. In vitro, P. gingivalis, particularly the more virulent strain W83, stimulated myeloid antigen presenting cells (APC) to drive Th17 polarization. Supernatants from myeloid APC exposed to P. gingivalis were capable of enhancing Th17 but not Th1 polarization. P. gingivalis favored the generation of Th17 responses by stimulating the production of Th17 related cytokines IL-1β, IL-6 and IL-23, but not Th1 related IL-12. By inducing NFκB activation, P. gingivalis promoted IL-1β, IL-6 and IL-12p40 production, but not IRF3 phosphorylation, connected to generation of the IL-12p35 chain, ultimately restricting formation of the intact IL-12 molecule. Promotion of Th17 lineage responses was also aided by P. gingivalis proteases, which appeared to differentially degrade pivotal cytokines. In this regard, IL-12 was largely degraded by P. gingivalis, whereas IL-1β was more resistant to proteolysis. Our data unveil multiple pathways by which P. gingivalis may orchestrate chronic inflammation, providing insights into interventional strategies.

Lack of efficacy of etanercept in Sjögren syndrome correlates with failed suppression of tumour necrosis factor α and systemic immune activation

Objective: To provide insight into the clinical failure of the tumour necrosis factor α (TNFα) inhibitor, etanercept, in primary Sjögren syndrome (pSS), an extensive analysis of the systemic immune profile of patients with pSS was carried out and the effect of etanercept treatment on these immune parameters monitored. Methods: Peripheral blood mononuclear cells of patients with pSS and healthy controls were compared by flow cytometry to determine differences in distribution of specific cell populations (T cells, B cells, monocytes), and to determine their expression of activation markers (CD25, HLA-DR), TNF receptors and chemokine receptors (CXCR1, 2) before and after treatment. Systemic cytokine levels were measured by multiplex ELISA assay in plasma and in lipopolysaccharide-stimulated whole blood from healthy controls and from patients with pSS before and after etanercept treatment. Baseline cytokine levels were correlated with clinical markers of disease. Results: Before treatment, salivary gland inflammatory focus scores did not correlate with circulating TNF levels. Furthermore, consistent with the lack of evidence of significant clinical benefit, enhanced markers of immune activation, frequency of cell subpopulations and aberrant cytokine profiles were not restored to normal levels by etanercept treatment. Remarkably, the levels of circulating TNFα were significantly increased after treatment. Conclusion: Etanercept is an ineffective therapeutic agent in pSS consistent with the absence of suppression of TNFα and other indicators of immune activation in this patient population. These data suggest that TNFα may not be a pivotal cytokine in the pathogenesis of pSS, impelling continued molecular characterisation of disease parameters to define appropriate intervention targets.

Aberrant mucosal wound repair in the absence of secretory leukocyte protease inhibitor

Secretory leukocyte protease inhibitor (SLPI) is a cationic serine protease inhibitor with anti-microbial and anti-inflammatory properties found in large quantities in mucosal fluids, including saliva. SLPI is expressed during cutaneous wound healing, however, its role in oral wound repair is unknown. We have used a novel approach involving a murine buccal mucosal acute wound model to investigate the role of SLPI in oral healing. In parallel to the observed cutaneous healing phenotype, an absence of SLPI results in markedly impaired oral wound healing associated with increased inflammation and raised elastase activity. Moreover, matrix deposition was decreased, while MMP activity was enhanced in the oral SLPI null wounds suggesting deregulated proteolysis. Intriguingly, regardless of genotype, reduced collagen deposition was observed in oral compared to dermal wounds, associated with reduced TGF-beta expression and decreased fibroblast collagen expression in vitro. We propose that SLPI is a pivotal endogenous factor necessary for optimal tissue repair including intra-oral wound healing. In addition, our model provides a unique opportunity to delineate the cellular and molecular mechanisms underlying the differences between dermal scarring and oral scar-free healing.

Lack of efficacy of etanercept in Sjögren’s syndrome correlates with failed suppression of TNFα and systemic immune activation

Objective: To provide insight into the clinical failure of the tumour necrosis factor α (TNFα) inhibitor, etanercept, in primary Sjögren syndrome (pSS), an extensive analysis of the systemic immune profile of patients with pSS was carried out and the effect of etanercept treatment on these immune parameters monitored. Methods: Peripheral blood mononuclear cells of patients with pSS and healthy controls were compared by flow cytometry to determine differences in distribution of specific cell populations (T cells, B cells, monocytes), and to determine their expression of activation markers (CD25, HLA-DR), TNF receptors and chemokine receptors (CXCR1, 2) before and after treatment. Systemic cytokine levels were measured by multiplex ELISA assay in plasma and in lipopolysaccharide-stimulated whole blood from healthy controls and from patients with pSS before and after etanercept treatment. Baseline cytokine levels were correlated with clinical markers of disease. Results: Before treatment, salivary gland inflammatory focus scores did not correlate with circulating TNF levels. Furthermore, consistent with the lack of evidence of significant clinical benefit, enhanced markers of immune activation, frequency of cell subpopulations and aberrant cytokine profiles were not restored to normal levels by etanercept treatment. Remarkably, the levels of circulating TNFα were significantly increased after treatment. Conclusion: Etanercept is an ineffective therapeutic agent in pSS consistent with the absence of suppression of TNFα and other indicators of immune activation in this patient population. These data suggest that TNFα may not be a pivotal cytokine in the pathogenesis of pSS, impelling continued molecular characterisation of disease parameters to define appropriate intervention targets.

Rapid Myeloid Cell Transcriptional and Proteomic Responses to Periodontopathogenic Porphyromonas gingivalis

Long-lived monocytes, macrophages, and dendritic cells (DCs) are Toll-like receptor-expressing, antigen-presenting cells derived from a common myeloid lineage that play key roles in innate and adaptive immune responses. Based on immunohistochemical and molecular analyses of inflamed tissues from patients with chronic destructive periodontal disease, these cells, found in the inflammatory infiltrate, may drive the progressive periodontal pathogenesis. To investigate early transcriptional signatures and subsequent proteomic responses to the periodontal pathogen, Porphyromonas gingivalis, donor-matched human blood monocytes, differentiated DCs, and macrophages were exposed to P. gingivalis lipopolysaccharide (LPS) and gene expression levels were measured by oligonucleotide microarrays. In addition to striking differences in constitutive transcriptional profiles between these myeloid populations, we identify a P. gingivalis LPS-inducible convergent, transcriptional core response of more than 400 annotated genes/ESTs among these populations, reflected by a shared, but quantitatively distinct, proteomic response. Nonetheless, clear differences emerged between the monocytes, DCs, and macrophages. The finding that long-lived myeloid inflammatory cells, particularly DCs, rapidly and aggressively respond to P. gingivalis LPS by generating chemokines, proteases, and cytokines capable of driving T-helper cell lineage polarization without evidence of corresponding immunosuppressive pathways highlights their prominent role in host defense and progressive tissue pathogenesis. The shared, unique, and/or complementary transcriptional and proteomic profiles may frame the context of the host response to P. gingivalis, contributing to the destructive nature of periodontal inflammation.

Dentinal hypersensitivity following scaling and root planing: comparison of low-level laser and topical fluoride treatment

The aim of this study is to compare the effectiveness of low-level laser irradiation to traditional topical fluoride treatment for treatment choices of dentinal hypersensitivity following scaling and root planing. The experimental group (15 patients) was treated with low-energy-level diode laser at each site of dentinal hypersensitivity following scaling and root planning. The control group (15 patients) received topical fluoride treatment (protective varnish for desensitization). All the patients were treated at baseline visit, and then at day 2 and 4 after the initial treatment; the pain was subjectively assessed by the patients as strong, medium, medium low, low, or no pain. Total absence of the dental hypersensitivity was reported in 26.66% of the examined group even after the second visit, compared to the control group where complete resolution of the hypersensitivity was not present after the second visit in any of the treated cases. Complete absence of pain was achieved in 86.6% of patients treated with laser and only in 26.6% in the fluoride treated group, after the third visit. Based on our findings, we conclude that low-energy biostimulative laser treatment can be successfully used for treatment of dental hypersensitivity following scaling and root planing.

Transcriptional events in a clinical model of oral mucosal tissue injury and repair

Tissue injury in the oral mucosa activates a cascade of transcriptional events important during the healing process that are not yet clearly defined. To characterize these events and identify potential gene targets for future studies, we used cDNA expression arrays in a clinical model of tissue injury. Mucosal biopsies were taken before third molar extraction, 2–4 hours postoperatively, or at 48 hours. Hybridization patterns were analyzed and validated using real‐time polymerase chain reaction. Prior to extraction, the biopsied mucosal tissues were characterized by a panoply of genes that were constitutively expressed. After injury, analysis revealed differential expression of genes involved in transcription, inflammation, and remodeling. At 2–4 hours after injury, genes such as Fos, Jun, and early growth response protein were up‐regulated, while genes responsible for intercellular adhesion were down‐regulated. At 48 hours after injury, the gene profile had shifted toward tissue remodeling. Here we identify genes constitutively expressed in normal oral mucosa and transcriptional events following mucosal tissue injury, which may be useful in identifying new therapeutic targets.

Oral Microbiome and Nitric Oxide: the Missing Link in the Management of Blood Pressure

Having high blood pressure puts you at risk for heart disease and stroke, which are leading causes of death in the USA and worldwide. One out of every three Americans has hypertension, and it is estimated that despite aggressive treatment with medications, only about half of those medicated have managed blood pressure. Recent discoveries of the oral microbiome that reduces inorganic nitrate to nitrite and nitric oxide provide a new therapeutic target for the management of hypertension. The presence or absence of select and specific bacteria may determine steady-state blood pressure levels. Eradication of oral bacteria through antiseptic mouthwash or overuse of antibiotics causes blood pressure to increase. Allowing recolonization of nitrate- and nitrite-reducing bacteria can normalize blood pressure. This review will provide evidence of the link between oral microbiota and the production of nitric oxide and regulation of systemic blood pressure. Management of systemic hypertension through maintenance of the oral microbiome is a completely new paradigm in cardiovascular medicine.

Limitations and options using resorbable versus nonresorbable membranes for successful guided bone regeneration

OBJECTIVE Deficient bony ridges often complicate the implant treatment plan. Several treatment modalities are used to regenerate bone, including guided bone regeneration (GBR). The purpose of this study was to summarize the knowledge on different types of membranes available and currently used in GBR procedures in a staged approach or with simultaneous implant placement. The primary role of the membranes is to exclude epithelial and connective tissue cells from the wound area to be regenerated, and to create and maintain the space into which pluripotential and osteogenic cells are free to migrate. DATA SOURCES A literature search was performed for articles that were published in English on the topic. A selected number of studies were chosen in order to provide a review of the main characteristics, applications, and outcomes of the different types of membranes. Resorbable membranes are made of natural or synthetic polymers like collagen and aliphatic polyesters. Collagens are the most common type used. They have similar collagen composition to the periodontal connective tissue. Other materials available include human, porcine, and bovine pericardium membranes, human amnion and chorion tissue, and human acellular freeze-dried dermal matrix. Nonresorbable membranes used in GBR include dense-polytetrafluoroethylene (d-PTFE), expanded-polytetrafluoroethylene (e-PTFE), titanium mesh, and titanium-reinforced polytetrafluoroethylene. CONCLUSIONS The most common complication of nonresorbable membranes is exposure, which has detrimental effect on the final outcome with both types of membranes. For vertical bone augmentation procedures, the most appropriate membranes are the nonresorbable. For combination defects, both types result in a successful outcome.

IL4 gene polymorphisms and their relation to periodontal disease in a Macedonian population

Genetic polymorphisms in the interleukin-4 (IL4) gene have been reported to influence the host response to microbial challenge by altering levels of cytokine expression. We analyzed nucleotide polymorphisms in the promoter region of the IL4 gene and its relation with periodontal disease in a Macedonian population. The study population consisted of 92 unrelated subjects with chronic periodontitis and 286 healthy controls. DNA was isolated and IL4 genotyping performed by polymerase chain reaction-single-strand polymorphism (Heidelberg kit) for the alleles and genotypes of IL4 -1098, IL4 -590, and IL4 -33. Frequencies of IL4 haplotypes and the haplotype zygotes were also examined. Comparisons between groups were tested using the Pearsons p value. After Bonferroni adjustment, significant associations were detected between subjects with periodontitis and the following: (1) cytokine alleles IL4 -1098 and IL4 -33; (2) cytokine genotypes IL4 -1098/G:T; IL4 -1098/T:T, and IL4 -33/T:T, (3) cytokine haplotypes IL4/GCC, IL4/TCC, and IL4/TTC; and (4) cytokine haplotype zygotes IL4/TTC: TCC, IL4/TCT:TTT, and IL4/GCC:TTC. Cytokine polymorphism on the IL4 gene appears to be associated with susceptibility to chronic periodontitis in Macedonians.