Delayed gingival wound healing is widely observed in periodontal patients with diabetes. However, the molecular mechanisms of the impaired function of gingival fibroblasts in diabetes remain unclear. ...The purpose of this study was to investigate changes in the properties of human gingival fibroblasts (HGFs) under high-glucose conditions. Primary HGFs were isolated from healthy gingiva and cultured with 5.5, 25, 50, and 75 mM glucose for 72 h. In vitro wound healing, 5-ethynyl-2'-deoxyuridine (EdU), and water-soluble tetrazolium salt (WST-8) assays were performed to examine cell migration and proliferation. Lactase dehydrogenase (LDH) levels were measured to determine cytotoxicity. The mRNA expression levels of oxidative stress markers were quantified by real-time PCR. Intracellular reactive oxygen species (ROS) were also measured in live cells. The antioxidant N-acetyl-l-cysteine (NAC, 1 mM) was added to evaluate the involvement of ROS in the glucose effect on HGFs. As a result, the in vitro wound healing assay showed that high glucose levels significantly reduced fibroblast migration and proliferation at 6, 12, 24, 36, and 48 h. The numbers of cells positive for EdU staining were decreased, as was cell viability, at 50 and 75 mM glucose. A significant increase in LDH was proportional to the glucose concentration. The mRNA levels of heme oxygenase-1 and superoxide dismutase-1 and ROS levels were significantly increased in HGFs after 72 h of exposure to 50 mM glucose concentration. The addition of NAC diminished the inhibitory effect of high glucose in the in vitro wound healing assay. The results of the present study show that high glucose impairs the proliferation and migration of HGFs. Fibroblast dysfunction may therefore be caused by high glucose-induced oxidative stress and may explain the delayed gingival wound healing in diabetic patients.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Periodontitis has been implicated as a risk factor for metabolic disorders such as type 2 diabetes, atherosclerotic vascular diseases, and non-alcoholic fatty liver disease. Although bacteremias from ...dental plaque and/or elevated circulating inflammatory cytokines emanating from the inflamed gingiva are suspected mechanisms linking periodontitis and these diseases, direct evidence is lacking. We hypothesize that disturbances of the gut microbiota by swallowed bacteria induce a metabolic endotoxemia leading metabolic disorders. To investigate this hypothesis, changes in the gut microbiota, insulin and glucose intolerance, and levels of tissue inflammation were analysed in mice after oral administration of Porphyromonas gingivalis, a representative periodontopathogens. Pyrosequencing revealed that the population belonging to Bacteroidales was significantly elevated in P. gingivalis-administered mice which coincided with increases in insulin resistance and systemic inflammation. In P. gingivalis-administered mice blood endotoxin levels tended to be higher, whereas gene expression of tight junction proteins in the ileum was significantly decreased. These results provide a new paradigm for the interrelationship between periodontitis and systemic diseases.
Porphyromonas gingivalis is a major pathogen of periodontal disease that affects a majority of adults worldwide. Increasing evidence shows that periodontal disease is linked to various systemic ...diseases like diabetes and cardiovascular disease, by contributing to increased systemic levels of inflammation. Lipopolysaccharides (LPS), as a key virulent attribute of P. gingivalis, possesses significant amount of lipid A heterogeneity containing tetra- (LPS1435/1449) and penta-acylated (LPS1690) structures. Hitherto, the exact molecular mechanism of P. gingivalis LPS involved in periodontal pathogenesis remains unclear, due to limited understanding of the specific receptors and signaling pathways involved in LPS-host cell interactions.
This study systematically investigated the effects of P. gingivalis LPS1435/1449 and LPS1690 on the expression of TLR2 and TLR4 signal transduction and the activation of pro-inflammatory cytokines IL-6 and IL-8 in human gingival fibroblasts (HGFs). We found that LPS1435/1449 and LPS1690 differentially modulated TLR2 and TLR4 expression. NF-κB pathway was significantly activated by LPS1690 but not by LPS1435/1449. In addition, LPS1690 induced significant expression of NF-κB and p38 MPAK pathways-related genes, such as NFKBIA, NFKB1, IKBKB, MAP2K4 and MAPK8. Notably, the pro-inflammatory genes including GM-CSF, CXCL10, G-CSF, IL-6, IL-8 and CCL2 were significantly upregulated by LPS1690 while down-regulated by LPS1435/1449. Blocking assays confirmed that TLR4-mediated NF-κB signaling was vital in LPS1690-induced expression of IL-6 and IL-8 in HGFs.
The present study suggests that the tetra- and penta-acylated lipid A structures of P. gingivalis LPS differentially activate TLR4-mediated NF-κB signaling pathway, and significantly modulate the expression of IL-6 and IL-8 in HGFs. The ability to alter the lipid A structure of LPS could be one of the strategies carried-out by P. gingivalis to evade innate host defense in gingival tissues, thereby contributing to periodontal pathogenesis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background
The periodontal phenotype consists of the bone morphotype, the keratinized tissue (KT), and gingival thickness (GT). The latter two components, overlying the bone, constitute the gingival ...phenotype. Several techniques have been proposed for enhancing or augmenting KT or GT. However, how phenotype modification therapy (PMT) affects periodontal health and whether the obtained outcomes are maintained over time have not been elucidated. The aim of the present review was to summarize the available evidence in regard to the utilized approaches for gingival PMT and assess their comparative efficacy in augmenting KT, GT and in improving periodontal health using autogenous, allogenic, and xenogeneic grafting approaches.
Methods
A detailed systematic search was performed to identify eligible randomized clinical trials (RCTs) reporting on the changes in GT and KT (primary outcomes). The selected articles were segregated into the type of approach based on having performed a root coverage, or non‐root coverage procedure. A network meta‐analysis (NMA) was conducted for each approach to assess and compare the outcomes among different treatment arms for the primary outcomes.
Results
A total of 105 eligible RCTs were included. 95 pertaining to root coverage (3,539 treated gingival recessions GRs), and 10 for non‐root coverage procedures (699 total treated sites). The analysis on root coverage procedures showed that all investigated techniques (the acellular dermal matrix ADM, collagen matrix CM, connective tissue graft CTG) are able to significantly increase the GT, compared with treatment with flap alone. However, KT was only significantly increased with the use of CTG or ADM. Early post‐treatment GT was found to inversely predict future GR. For non‐root coverage procedures, only the changes in KT could be analyzed; all investigated treatment groups (ADM, CM, free gingival graft FGG, living cellular construct LCC, in combination with an apically positioned flap APF), resulted in significantly more KT than treatment with APF alone. Additionally, the augmented GT was shown to be sustained, and KT displayed an incremental increase over time.
Conclusions
Within its limitations, it was observed that any graft material was able to significantly enhance GT, while KT in root coverage procedures was significantly enhanced with CTG and ADM, and in non‐root coverage procedures, with ADM, CM, FGG, and LCC compared with APF alone. The autogenous soft tissue graft (CTG/FGG) proved to be superior in all comparisons for both outcomes of GT and KT.
Immuno-surveillance networks operating at barrier sites are tuned by local tissue cues to ensure effective immunity. Site-specific commensal bacteria provide key signals ensuring host defense in the ...skin and gut. However, how the oral microbiome and tissue-specific signals balance immunity and regulation at the gingiva, a key oral barrier, remains minimally explored. In contrast to the skin and gut, we demonstrate that gingiva-resident T helper 17 (Th17) cells developed via a commensal colonization-independent mechanism. Accumulation of Th17 cells at the gingiva was driven in response to the physiological barrier damage that occurs during mastication. Physiological mechanical damage, via induction of interleukin 6 (IL-6) from epithelial cells, tailored effector T cell function, promoting increases in gingival Th17 cell numbers. These data highlight that diverse tissue-specific mechanisms govern education of Th17 cell responses and demonstrate that mechanical damage helps define the immune tone of this important oral barrier.
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•Distinct signals shape the Th17 cell network at the oral barrier•Oral barrier Th17 cells develop independently of commensal microbe colonization•Physiologic damage through mastication promotes the generation of oral Th17 cells•Barrier damage triggers oral Th17-cell-mediated protective immunity and inflammation
The signals regulating immunity at the gingiva, a key oral barrier, remain unclear. Dutzan et al. show that oral barrier Th17 cells are induced in response to mastication rather than commensal colonization, identifying physiologic mechanical damage as a unique tissue-specific cue conditioning local immunity and inflammation at the oral barrier.
Aside from the well-established self-renewal and multipotent differentiation properties, mesenchymal stem cells exhibit both immunomodulatory and anti-inflammatory roles in several experimental ...autoimmune and inflammatory diseases. In this study, we isolated a new population of stem cells from human gingiva, a tissue source easily accessible from the oral cavity, namely, gingiva-derived mesenchymal stem cells (GMSCs), which exhibited clonogenicity, self-renewal, and multipotent differentiation capacities. Most importantly, GMSCs were capable of immunomodulatory functions, specifically suppressed peripheral blood lymphocyte proliferation, induced expression of a wide panel of immunosuppressive factors including IL-10, IDO, inducible NO synthase (iNOS), and cyclooxygenase 2 (COX-2) in response to the inflammatory cytokine, IFN-gamma. Cell-based therapy using systemic infusion of GMSCs in experimental colitis significantly ameliorated both clinical and histopathological severity of the colonic inflammation, restored the injured gastrointestinal mucosal tissues, reversed diarrhea and weight loss, and suppressed the overall disease activity in mice. The therapeutic effect of GMSCs was mediated, in part, by the suppression of inflammatory infiltrates and inflammatory cytokines/mediators and the increased infiltration of regulatory T cells and the expression of anti-inflammatory cytokine IL-10 at the colonic sites. Taken together, GMSCs can function as an immunomodulatory and anti-inflammatory component of the immune system in vivo and is a promising cell source for cell-based treatment in experimental inflammatory diseases.
Solitary chemosensory cells (SCCs) are epithelial sentinels that utilize bitter Tas2r receptors and coupled taste transduction elements to detect pathogenic bacterial metabolites, triggering host ...defenses to control the infection. Here we report that SCCs are present in mouse gingival junctional epithelium, where they express several Tas2rs and the taste signaling components α-gustducin (Gnat3), TrpM5, and Plcβ2. Gnat3
mice have altered commensal oral microbiota and accelerated naturally occurring alveolar bone loss. In ligature-induced periodontitis, knockout of taste signaling molecules or genetic absence of gingival SCCs (gSCCs) increases the bacterial load, reduces bacterial diversity, and renders the microbiota more pathogenic, leading to greater alveolar bone loss. Topical treatment with bitter denatonium to activate gSCCs upregulates the expression of antimicrobial peptides and ameliorates ligature-induced periodontitis in wild-type but not in Gnat3
mice. We conclude that gSCCs may provide a promising target for treating periodontitis by harnessing innate immunity to regulate the oral microbiome.
Background: The role of keratinized tissue (KT) for maintenance of periodontal health has been debated for many years. This study assesses the long‐term “biologic remodeling” of periodontal ...dimensions of teeth treated with free gingival grafts (FGGs) compared with adjacent/untreated teeth.
Methods: Seventy‐four patients with at least one site showing absence or a reduced amount of attached gingiva associated with gingival recession (GR) at baseline were treated with FGGs in a private practice. Patient/tooth/site‐associated variables were recorded for each patient (treated and mesial/distal adjacent teeth) at baseline (T0), 6 months after surgery (T1), during the follow up period (T2) (mean 15.3 years), and at the end of the follow‐up period (T3) over 25 years. Parametric, non‐parametric, and mixed effects logistic regression statistics were used throughout the study.
Results: A total of 182 teeth submitted to FGGs were compared with 247 untreated/adjacent teeth. The majority of treated teeth (n = 152; 83.5%) showed GR depth (GRD) reduction (P <0.001). Conversely, untreated/adjacent teeth displayed GRD increase at T3 (P <0.001). Statistically significant KT band contraction was also found at treated sites, whereas adjacent sites presented small clinical improvements (P <0.001). The total root‐coverage esthetic score of the areas including treated and adjacent untreated teeth improved from T2 to T3 (P <0.001). Some independent variables, such as age, tooth type, and GRD at T1 seem to influence GRD and KT changes over time.
Conclusions: Soft tissue augmentation procedures may modify the biologic remodeling of periodontal dimensions over time associated with aging. Use of FGGs may promote more favorable KT dimensions and improve marginal tissue recession.
The Th17/IL‐17 pathway is implicated in the pathogenesis of periodontitis (PD), however the mechanisms are not fully understood. We investigated the mechanism by which the periodontal pathogens ...Porphyromonas gingivalis (Pg) and Aggregatibacter actinomycetemcomitans (Aa) promote a Th17/IL‐17 response in vitro, and studied IL‐17+ CD4+ T‐cell frequencies in gingival tissue and peripheral blood from patients with PD versus periodontally healthy controls. Addition of Pg or Aa to monocyte/CD4+ T‐cell co‐cultures promoted a Th17/IL‐17 response in vitro in a dose‐ and time‐dependent manner. Pg or Aa stimulation of monocytes resulted in increased CD40, CD54 and HLA‐DR expression, and enhanced TNF‐α, IL‐1β, IL‐6 and IL‐23 production. Mechanistically, IL‐17 production in Pg‐stimulated co‐cultures was partially dependent on IL‐1β, IL‐23 and TLR2/TLR4 signalling. Increased frequencies of IL‐17+ cells were observed in gingival tissue from patients with PD compared to healthy subjects. No differences were observed in IL‐17+ CD4+ T‐cell frequencies in peripheral blood. In vitro, Pg induced significantly higher IL‐17 production in anti‐CD3 mAb‐stimulated monocyte/CD4+ T‐cell co‐cultures from patients with PD compared to healthy controls. Our data suggest that periodontal pathogens can activate monocytes, resulting in increased IL‐17 production by human CD4+ T cells, a process that appears enhanced in patients with PD.
Periodontal pathogens Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans activate human monocytes to produce IL‐1β, IL‐23, IL‐6 and TNF‐α, leading to enhanced IL‐17 production by CD4+ T cells in vitro. Our data suggest that the effect on IL‐17 production is enhanced in T cells from patients with periodontitis.
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