Regulation of NAMPT in human gingival fibroblasts and biopsies

Expression of visfatin in gingival crevicular fluid and gingival tissues in different periodontal conditions: a cross-sectional study

BACKGROUND

Studies have shown that visfatin is an inflammatory factor closely related to periodontitis. We examined the levels of visfatin in gingival crevicular fluid (GCF) and gingival tissues under different periodontal conditions, in order to provide more theoretical basis for exploring the role of visfatin in the pathogenesis of periodontitis.

METHODS

We enrolled 87 subjects, with 43 in the chronic periodontitis (CP) group, 21 in the chronic gingivitis (CG) group, and 23 in the periodontal health (PH) group. Periodontal indexes (PD, AL, PLI, and BI) were recorded. GCF samples were collected for visfatin quantification, and gingival tissues were assessed via immunohistochemical staining.

RESULTS

Visfatin levels in GCF decreased sequentially from CP to CG and PH groups, with statistically significant differences (P < 0.05). The CP group exhibited the highest visfatin levels, while the PH group had the lowest. Gingival tissues showed a similar trend, with significant differences between groups (P < 0.001). Periodontal indexes were positively correlated with visfatin levels in both GCF and gingival tissues (P < 0.001). A strong positive correlation was observed between visfatin levels in GCF and gingival tissues (rs = 0.772, P < 0.001).

CONCLUSION

Greater periodontal destruction corresponded to higher visfatin levels in GCF and gingival tissues, indicating their potential collaboration in damaging periodontal tissues. Visfatin emerges as a promising biomarker for periodontitis and may play a role in its pathogenesis.

Obesity and Oral Health: The Link Between Adipokines and Periodontitis

Periodontitis is a chronic inflammatory disease of the periodontium, or the supportive tissues around the tooth. This disease has been related to different risk factors, such as the presence of plaque and calculus, tobacco smoking, low socioeconomic status, and the immune state of the host. Importantly, the chronic inflammatory environment generated by periodontitis may lead to tooth loss and diverse systemic complications, such as cardiovascular disease, osteoarthritis and metabolic disease. Recent investigations have supported the role of obesity as a risk factor for periodontitis. Furthermore, studies have found obesity to compromise healing after periodontal therapy; however, the mechanisms underlying this association are not well understood. Proteins called 'adipokines' could be the factor linking obesity to periodontitis. Adipokines are bioactive molecules with hormonal properties and a structure similar to cytokines produced by the adipose tissue. Although adipokines have both pro-and anti-inflammatory effects, the shift towards pro-inflammatory actions occurs when the adipose tissue becomes pathological, as observe in the progression of conditions such as obesity or adiposopathy. This article reviews the role of adipokines in the pathophysiology and progression of periodontitis by focusing on their impact on inflammation and the molecular mechanisms through which adipokines contribute to the onset and development of periodontitis.

Association between visfatin and periodontitis: a systematic review and meta-analysis

Background

Periodontitis is a chronic inflammatory disease caused by bacterial infection in the periodontal support tissue. Visfatin, a hormone secreted mainly by adipocytes and macrophages, plays an important role in immune regulation and defense. Although studies have indicated that patients with periodontitis have significantly high serum and gingival crevicular fluid levels of visfatin, the relationship between this adipocytokine and periodontal disease remains unclear.

Aim

The aim of this study was to systematically evaluate the association between visfatin levels and periodontitis.

Methods

The PubMed, Web of Science, ScienceDirect, EBSCO, and Wiley Online Library databases were searched for potential studies, using "periodontitis" and "visfatin" as the keywords in the title and abstract search fields. Standardized mean difference (SMD) values with corresponding 95% confidence intervals (CIs) were determined from the results of this meta-analysis.

Results

In total, 22 articles involving 456 patients with periodontitis and 394 healthy individuals (controls) were included in the meta-analysis. Visfatin levels were significantly higher in the patients with periodontitis than in the healthy individuals (SMD: 3.82, 95% CI [3.01-4.63]). Moreover, the visfatin levels were significantly lowered after periodontitis treatment (SMD: -2.29, 95% CI [-3.33 to -1.26]).

Conclusion

This first-ever meta-analysis comparing visfatin levels between patients with periodontitis and healthy individuals suggests that this adipocytokine can be a diagnostic and therapeutic biomarker for periodontal disease.

Effect of non-surgical periodontal treatment on visfatin and chemerin concentration in the gingival crevicular fluid

Visfatin, as a novel adipokine, is considered to play a role in periodontal inflammation. Chemerin is another newly identified adipokine that is possible to have a role in periodontitis firstly reported in our previous study. The aim of the current study is to evaluate the gingival crevicular fluid (GCF) levels of visfatin and chemerin in periodontitis and and compare these adipokine levels with before and after non-surgical periodontal treatment. Twenty-nine patients with Stage III Grade B periodontitis and eighteen healthy subjects included in this cross-sectional cohort study. Clinical periodontal parameters and GCF were obtained from all subjects. Eight weeks after the following non-surgical periodontal treatment including scaling and root planning, samples and clinical periodontal parameters were collected again in the periodontitis group. The levels of adipokines were analyzed with standard enzyme-linked immunosorbent assay. The levels of visfatin and chemerin were statistically significantly higher at periodontitis group as compared to healthy group (P < 0.001). Although, no changes were observed in visfatin levels after periodontal treatment (P > 0.05), chemerin levels were significantly decreased (P < 0.001). Also, no differences were observed as compared to the healthy group (P > 0.05). Visfatin and chemerin may play a role in the periodontal disease process. In addition, it can be considered that the decreased chemerin levels after non-surgical periodontal treatment may play an important role for developing host modulation strategies.

Gingival crevicular fluid levels of apelin correlates with clinical periodontal diagnosis

OBJECTIVES

Limitations of clinical periodontal measurements have led to the search for reliable biomarkers that can be used in diagnosis and monitoring of periodontal diseases. Considering the relationship of adipokines with periodontal disease, diabetes, and obesity, apelin may be a biomarker for periodontal diseases due to its modulating effects on inflammation. The present study was conducted to determine gingival crevicular fluid (GCF) apelin levels in systemically healthy individuals and to evaluate the potential of apelin as a biomarker for periodontal diagnosis.

MATERIALS AND METHODS

Ten individuals with clinically healthy periodontal tissues, 10 patients diagnosed with gingivitis, and 10 patients with periodontitis were included in the present study. Whole mouth clinical periodontal measurements were recorded and GCF samples were obtained from the buccal approximal regions of single-rooted teeth with features that would represent clinical periodontal diagnosis. Apelin level in the samples was determined by ELISA. Clinical and biochemical findings were statistically analyzed. Possible relationship between the variables was evaluated with Pearson correlation analysis.

RESULTS

Apelin level in the gingivitis group was higher than that in the clinically healthy group (p = 0.000) and lower than that in the periodontitis group (p = 0.000). A positive correlation was found between GCF apelin concentration and plaque score, bleeding on probing, and probing depth (p = 0.000).

CONCLUSIONS

Within the limits of this study, it can be suggested that GCF apelin concentration may be a biomarker that can distinguish between healthy periodontal tissues, gingivitis, and periodontitis patients.

CLINICAL RELEVANCE

Apelin concentration in the gingival crevicular fluid may aid in the diagnosis of periodontal disease.

Effects of probiotics in rats with experimental metabolic syndrome and periodontitis: An investigation of the intestine-adipose tissue axis

BACKGROUND

This study evaluated the systemic (intestine and adipose tissue) and local (periodontal tissues) impact of probiotic therapy in rats with metabolic syndrome (MS) associated or not with periodontitis (PE).

METHODS

Forty-eight rats received a high-fat diet for induction of MS for 16 weeks. They were subdivided into groups with (+) and without (-) PE, receiving (*) or not (**) receiving probiotics (PROB): MS (-**), MSP (-*), MSPE (+**), and MSPEP (+*). PROB administration (Bifidobacterium animalis subsp. lactis HN019) started on the 8th week of the study and PE was induced on the 14th week by placing ligature on the animals' lower first molars. Euthanasia occurred in the 16th week. Biomolecular, immunoenzymatic assays, and histomorphometric analyses were performed. The data obtained were statistically analyzed (ANOVA, Tukey, p < 0.05).

RESULTS

The MSPEP group exhibited reduced alveolar bone loss when compared with the MSPE group, as well as lower levels of hepatic steatosis and proteinuria (p < 0.05). In the intestinal environment, the MSPE group exhibited significantly lower villus height and crypt depth, as well as a greater increase in Bacillota when compared with the MSPEP group (p < 0.05). The MSPEP group showed lower adipokine gene expression (LEPR, NAMPT, and FABP4) in adipose tissue than the MSPE group (p < 0.05).

CONCLUSION

The probiotic B. lactis HN019 reduced the severity of experimental periodontitis and modulated the expression of lipogenic genes and intestinal morphological and microbiological parameters in rats with MS.

Bifidobacterium animalis subspecies lactis HN019 can reduce the sequelae of experimental periodontitis in rats modulating intestinal parameters, expression of lipogenic genes, and levels of hepatic steatosis

OBJECTIVE

To determine whether Bifidobacterium animalis subspecies lactis HN019 (B. lactis HN019) can reduce the sequelae of experimental periodontitis (EP) in rats modulating systemic parameters.

BACKGROUND

This study evaluated the effects of probiotic therapy (PROB) in the prevention of local and systemic damage resulting from EP.

METHODS

Forty-eight rats were allocated into four groups: C (control), PROB, EP, and EP-PROB. PROB (1 × 1010  CFU/mL) administration lasted 8 weeks and PE was induced on the 7th week by placing ligature on the animals' lower first molars. All animals were euthanized in the 9th week of the experiment. Biomolecular analyses, RT-PCR, and histomorphometric analyses were performed. The data obtained were analyzed statistically (ANOVA, Tukey, p < .05).

RESULTS

The EP group had higher dyslipidemia when compared to the C group, as well as higher levels of insulin resistance, proteinuria levels, percentages of systolic blood pressure, percentage of fatty hepatocytes in the liver, and expression of adipokines was up-regulated (LEPR, NAMPT, and FABP4). All these parameters (except insulin resistance, systolic blood pressure, LEPR and FABP4 gene expression) were reduced in the EP-PROB group when compared to the EP group. The EP group had lower villus height and crypt depth, as well as a greater reduction in Bacteroidetes and a greater increase in Firmicutes when compared to the EP-PROB group. Greater alveolar bone loss was observed in the EP group when compared to the EP-PROB group.

CONCLUSION

Bifidobacterium lactis HN019 can reduce the sequelae of EP in rats modulating intestinal parameters, attenuating expression of lipogenic genes and hepatic steatosis.

Genome-Wide Analysis of Dental Caries Variability Reveals Genotype-by-Environment Interactions

Genotype-by-environment interactions (GEI) may influence dental caries, although their effects are difficult to detect. Variance quantitative trait loci (vQTL) may serve as an indicator of underlying GEI effects. The aim of this study was to investigate GEI effects on dental caries by prioritizing variants from genome-wide vQTL analysis. First, we identified vQTLs from ~4.3 M genome-wide variants in three cohorts of white children aged 3–5 (n = 396, n = 328, n = 773) using Levene’s test. A total of 39 independent vQTLs with p < 1 × 10−6 were identified, some of which were located in or near genes with plausible biological roles in dental caries (IGFBP7, SLC5A8, and SHH involved in tooth development and enamel mineralization). Next, we used linear regression to test GEI effects on dental caries with the 39 prioritized variants and self-reported environmental factors (demographic, socioeconomic, behavioral, and dietary factors) in the three cohorts separately. We identified eight significant GEIs indicating that children with vQTL risk genotypes had higher caries experience if they had less educated parents, lower household/parental income, brushed their teeth less frequently, consumed sugar-sweetened beverages more frequently, were not breastfed, and were female. We reported the first genome-wide vQTL analysis of dental caries in children nominating several novel genes and GEI for further investigations.

Apelin Enhances the Effects of Fusobacterium nucleatum on Periodontal Ligament Cells In Vitro

This study aimed to explore effects of Fusobacterium nucleatum with or without apelin on periodontal ligament (PDL) cells to better understand pathomechanistic links between periodontitis and obesity. First, the actions of F. nucleatum on COX2, CCL2, and MMP1 expressions were assessed. Subsequently, PDL cells were incubated with F. nucleatum in the presence and absence of apelin to study the modulatory effects of this adipokine on molecules related to inflammation and hard and soft tissue turnover. Regulation of apelin and its receptor (APJ) by F. nucleatum was also studied. F. nucleatum resulted in elevated COX2, CCL2, and MMP1 expressions in a dose- and time-dependent manner. Combination of F. nucleatum and apelin led to the highest (p < 0.05) expression levels of COX2, CCL2, CXCL8, TNF-α, and MMP1 at 48 h. The effects of F. nucleatum and/or apelin on CCL2 and MMP1 were MEK1/2- and partially NF-κB-dependent. The combined effects of F. nucleatum and apelin on CCL2 and MMP1 were also observed at protein level. Moreover, F. nucleatum downregulated (p < 0.05) the apelin and APJ expressions. In conclusion, obesity could contribute to periodontitis through apelin. The local production of apelin/APJ in PDL cells also suggests a role of these molecules in the pathogenesis of periodontitis.

The human oral virome: Shedding light on the dark matter

Mediators of the initiation, development, and recurrence of periodontitis include the oral microbiome embedded in subgingival plaque and the host immune response to a dysbiosis within this dynamic and complex microbial community. Although mediators have been studied extensively, researchers in the field have been unable to fully ascribe certain clinical presentations of periodontitis to their nature. Emergence of high-throughput sequencing technologies has resulted in better characterization of the microbial oral dysbiosis that extends beyond the extensively studied putative bacterial periodontopathogens to a shift in the oral virome composition during disease conditions. Although the biological dark matter inserted by retroviruses was once believed to be nonfunctional, research has revealed that it encodes historical viral-eukaryotic interactions and influences host development. The objective of this review is to evaluate the proposed association of herpesviruses to the etiology and pathogenesis of periodontal disease and survey the highly abundant prokaryotic viruses to delineate their potential roles in biofilm dynamics, as well as their interactions with putative bacterial periodontopathogens and eukaryotic cells. The findings suggest that potential novel periodontal therapies targeting or utilizing the oral virome can alleviate certain clinical presentations of periodontitis. Perhaps it is time to embrace the viral dark matter within the periodontal environment to fully comprehend the pathogenesis and systemic implications of periodontitis.

Visfatin regulates Pg LPS-induced proinflammatory/prodegradative effects in healthy and inflammatory periodontal cells partially via NF-κB pathway

Periodontitis is a widespread chronic infectious-inflammatory disease associated with multiple systemic diseases. Visfatin is an adipokine-enzyme that can be locally produced by human periodontal ligament cells (hPDLCs) and human gingival fibroblasts (hGFs). It can upregulate proinflammatory cytokines and matrix metalloproteinases (MMPs) in various types of cells. However, the effects of visfatin on healthy and inflammatory human periodontal cells as well as the underlying molecular mechanisms remain unclear. This study firstly demonstrated visfatin expression was highly elevated in inflamed human gingiva and Pg LPS-treated hPDLCs. Moreover, recombinant visfatin significantly upregulated the expression of proinflammatory cytokines (TNF-α, IL-1β and IL-6) and prodegradative factors (EMPPRIN, MMP1, MMP3 and MMP13) in hPDLCs. Next, we found the levels of proinflammatory and prodegradative cytokines were significantly increased in visfatin-overexpressing hPDLCs, and decreased in visfatin-silencing inflammatory hGFs (iGFs) when treated with Pg LPS. In the absence of Pg LPS, visfatin silencing failed to affect the expression of these factors in iGFs, and overexpression of visfatin upregulated MMPs but no other factors in hPDLCs. Furthermore, marked NF-κB pathway activation with increased phosphorylation of p65 was observed in visfatin-overexpressing hPDLCs. BAY11-7082, a specific inhibitor of NF-κB, partially reversed the upregulation proinflammatory and prodegradative factors induced by visfatin overexpression. Taken together, this study showed that visfatin critically regulates Pg LPS-induced proinflammatory/prodegradative effects in healthy and inflammatory periodontal cells partially via NF-κB pathway. The findings suggest that visfatin is closely involved in the development of periodontitis, and may serve as a promising novel biomarker and therapeutic target for periodontitis management.

Filifactor alocis and Tumor Necrosis Factor-Alpha Stimulate Synthesis of Visfatin by Human Macrophages

There is little known about the effect of the periodontopathogen Filifactor alocis on macrophages as key cells of the innate immune defense in the periodontium. Therefore, the aim of the present study was to investigate the effect of F. alocis and additionally of the pro-inflammatory cytokine tumor necrosis factor-alpha (TNFα) on visfatin and other pro-inflammatory and proteolytic molecules associated with periodontitis in human macrophages. The presence of macrophage markers CD14, CD86, CD68, and CD163 was examined in gingival biopsies from healthy individuals and periodontitis patients. Human macrophages were incubated with F. alocis and TNFα for up to 2 d. The effects of both stimulants on macrophages were determined by real-time PCR, ELISA, immunocytochemistry, and immunofluorescence. F. alocis was able to significantly stimulate the synthesis of visfatin by human macrophages using TLR2 and MAPK pathways. In addition to visfatin, F. alocis was also able to increase the synthesis of cyclooxygenase 2, TNFα, and matrix metalloproteinase 1. Like F. alocis, TNFα was also able to stimulate the production of these proinflammatory and proteolytic molecules. Our results highlight the pathogenetic role of F. alocis in periodontal diseases and also underline the involvement of visfatin in the aetiopathogenesis of periodontitis.

Evaluation of association between Porphyromonas gingivalis and visfatin levels in chronic periodontitis patients

Background:

Periodontal disease is one of the most common prevailing diseases, where the destruction occurs due to the direct effect of microorganisms and indirectly by the stimulation of host cells. The diverse inflammatory action of visfatin made this adipokine a potential periodontal biomarker of choice along with the periopathogen Porphyromonas gingivalis.

Aim:

Our study was carried out to evaluate the visfatin levels in gingival crevicular fluid (GCF) and P. gingivalis levels in subgingival plaque in periodontal health and disease.

Materials and Methods:

A total of 60 participants were divided into two groups of thirty participants each as Group I – patients who have healthy periodontium and Group II – patients with generalized chronic periodontitis. The clinical parameters assessed for the participants were plaque index, probing pocket depth, papillary bleeding index, and clinical attachment loss. The subgingival plaque samples were obtained to estimate P. gingivalis levels and GCF was collected to check visfatin levels.

Results:

The clinical parameters, P. gingivalis, and GCF visfatin levels between the two groups showed a notable significant difference. A significant positive correlation was noted on the correlation of GCF visfatin levels with clinical parameters.

Conclusion:

Our study outcomes propose that P. gingivalis can be the bonafide periopathogen which modulate the visfatin levels in individuals with periodontal disease and GCF visfatin can also be evaluated as a biomarker in periodontal disease.

Regulation of Anti-Apoptotic SOD2 and BIRC3 in Periodontal Cells and Tissues

The aim of the study was to clarify whether orthodontic forces and periodontitis interact with respect to the anti-apoptotic molecules superoxide dismutase 2 (SOD2) and baculoviral IAP repeat-containing protein 3 (BIRC3). SOD2, BIRC3, and the apoptotic markers caspases 3 (CASP3) and 9 (CASP9) were analyzed in gingiva from periodontally healthy and periodontitis subjects by real-time PCR and immunohistochemistry. SOD2 and BIRC3 were also studied in gingiva from rats with experimental periodontitis and/or orthodontic tooth movement. Additionally, SOD2 and BIRC3 levels were examined in human periodontal fibroblasts incubated with Fusobacterium nucleatum and/or subjected to mechanical forces. Gingiva from periodontitis patients showed significantly higher SOD2, BIRC3, CASP3, and CASP9 levels than periodontally healthy gingiva. SOD2 and BIRC3 expressions were also significantly increased in the gingiva from rats with experimental periodontitis, but the upregulation of both molecules was significantly diminished in the concomitant presence of orthodontic tooth movement. In vitro, SOD2 and BIRC3 levels were significantly increased by F. nucleatum, but this stimulatory effect was also significantly inhibited by mechanical forces. Our study suggests that SOD2 and BIRC3 are produced in periodontal infection as a protective mechanism against exaggerated apoptosis. In the concomitant presence of orthodontic forces, this protective anti-apoptotic mechanism may get lost.

Evaluation of adipokines and inflammatory mediator expression levels in patients with periodontitis and peri-implantitis: a cross-sectional study

OBJECTIVES

The aim of this study was to analyze the mRNA and protein expression of adiponectin, leptin, visfatin, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 levels in periodontitis and peri-implantitis sites in systemically healthy individuals and to investigate the influence of the presence of current periodontitis on their expression levels in peri-implantitis sites.

MATERIALS AND METHODS

Soft tissue biopsy samples were collected from 60 systemically healthy patients [15 periodontally healthy patients (group I), 16 patients with periodontitis (group II), 15 patients with peri-implantitis (group III), and 14 patients with peri-implantitis and periodontitis (group IV)]; mRNA expression levels of adiponectin, leptin, visfatin, TNF-α, and IL-6 were measured by quantitative real-time PCR; and their protein levels were assessed by immunohistochemistry.

RESULTS

The mRNA expression levels of all biomarkers were significantly higher for group II compared to group I, while significantly higher levels of leptin, TNF-α, and IL-6 were observed in group III in comparison with group I. Group II exhibited significantly higher mRNA expression of adiponectin and TNF-α than group III. Group IV showed significantly higher expression levels of adiponectin, leptin, TNF-α, and IL-6 compared to group III. Regarding the expression of protein levels, which was estimated through quantification of the histoscore, both groups II and III presented higher H-scores than group I for all biomarkers except leptin.

CONCLUSIONS

The presence of current periodontitis may enhance expression levels of adiponectin, leptin, TNF-α, and IL-6 in peri-implant soft tissue.

CLINICAL RELEVANCE

The presence of periodontitis is an important risk factor for the severity of peri-implant inflammation as well as the onset of peri-implantitis.

The association of periodontal diseases with metabolic syndrome and obesity

Periodontitis is a multifactorial chronic inflammatory disease associated with dysbiotic plaque biofilms and characterized by progressive destruction of the tooth-supporting apparatus. Globally, it is estimated that 740 million people are affected by its severe form. Periodontitis has been suggested to be linked to obesity and metabolic syndrome. Obesity, defined as excessive fat accumulation, is a complex multifactorial chronic inflammatory disease, with a high and increasing prevalence. Metabolic syndrome is defined as a cluster of obesity, dyslipidemia, hypertension, and dysglycemia. Obesity, metabolic syndrome and periodontitis are among the most common non-communicable diseases and a large body of evidence from epidemiologic studies supports the association between these conditions. Extensive research has established plausible mechanisms to explain how these conditions can negatively impact each other, pointing to a bidirectional adverse relationship. At present there is only limited evidence available from a few intervention studies. Nevertheless, the global burden of periodontitis combined with the obesity epidemic has important clinical and public health implications for the dental team. In accordance with the common risk factor approach for tackling non-communicable diseases, it has been proposed that oral healthcare professionals have an important role in the promotion of periodontal health and general well-being through facilitation of healthy lifestyle behaviours.

Regulation of Cyclooxygenase 2 by Filifactor alocis in Fibroblastic and Monocytic Cells

Periodontitis is a prevalent chronic inflammatory disease triggered by a synergistic and dysbiotic microbiota present in the oral biofilm. This in vitro study is aimed at evaluating the regulation of cyclooxygenase (COX)2 expression and production by the periodontopathogen Filifactor alocis in human gingival fibroblastic (HGF-1) and monocytic (THP-1) cells and also at investigating the underlying cellular pathway mechanisms. HGF-1 and THP-1 cells were exposed either to F. alocis or to the proinflammatory cytokine tumor necrosis factor alpha (TNFα) for 1 and 2 d to examine the COX2 expression by qPCR. COX2 protein levels were evaluated by ELISA in F. alocis-stimulated cells. Both types of cells were also stimulated with a blocking toll-like receptor (TLR)2 antibody or specific inhibitors against MAPKs. F. alocis significantly (p < 0.05) increased COX2 at both transcriptional and protein levels in both HGF-1 and THP-1 cells. Moreover, the stimulatory effect of F. alocis on COX2 was more pronounced in HGF-1 cells in comparison to THP-1 cells. F. alocis upregulated the COX2 expression in a dose-dependent manner in both type cells at 1 d. TNFα also significantly (p < 0.05) increased the COX2 expression in both cells. After preincubation of HGF-1 and THP-1 cells either with a neutralizing anti-TLR2 antibody or with specific MAPK inhibitors, the F. alocis-upregulated COX2 expression was significantly (p < 0.05) suppressed at 1 d. Our in vitro study provides original evidence that F. alocis stimulates COX2 production in fibroblastic and monocytic cells through TLR2 and MAPK mechanisms, suggesting a role of this periodontopathogen in the etiopathogenesis of periodontitis.

Resistin Is Increased in Periodontal Cells and Tissues: In Vitro and In Vivo Studies

Resistin, a proinflammatory adipokine, is elevated in many inflammatory diseases. However, little is known about its performance in periodontitis. The present study is aimed at evaluating resistin expression and synthesis in periodontal cells and tissues under inflammatory/microbial stress in addition to its effects on the periodontium. In vivo, 24 male rats were randomly divided into two groups: control and ligature-induced periodontal disease. After 6 and 12 days, animals were sacrificed to analyze gene expression of adipokines, bone loss, inflammation, and resistin synthesis. In vitro, human periodontal ligament (PDL) fibroblasts were used to evaluate the expression of resistin after inflammatory stimuli. In addition, PDL fibroblasts were exposed to resistin to evaluate its role on soft and hard tissue metabolism markers. The periodontitis group demonstrated significant bone loss, an increase in the number of inflammatory cells and vascular structures, an increase in resistin expression and synthesis, and a decrease in the expression of adiponectin, leptin, and its functional receptor. PDL fibroblasts showed a significant increase in resistin expression and synthesis in response to the inflammatory stimulus by IL-1β. Resistin induced an increase in cytokine expression and a decrease in the regulation of some hard tissue and matrix formation genes in PDL fibroblasts. These data indicate that resistin is produced by periodontal cells and tissues, and this effect is enhanced by inflammatory stimuli. Moreover, resistin seems to interfere with soft and hard tissue metabolism during periodontitis by reducing markers related to matrix formation and bone tissue.

Regulation of matrix metalloproteinase-1 by Filifactor alocis in human gingival and monocytic cells

OBJECTIVES

Periodontitis is a highly prevalent chronic inflammatory disease caused by periodontopathogens, such as Filifactor alocis. This study sought to examine the matrix metalloproteinase (MMP)-1 synthesis by monocytic and fibroblastic cells in response to F. alocis and to unravel the underlying cellular mechanisms.

MATERIAL AND METHODS

Gingival biopsies from periodontally healthy and periodontitis individuals were analyzed for the presence of F. alocis and MMP-1 by RT-PCR. Human gingival fibroblastic (HGF-1) and monocytic (THP-1) cells were stimulated with F. alocis in the presence and absence of a blocking toll-like receptor (TLR)2 antibody or specific inhibitors against MAPKs. MMP-1 expression and protein levels were studied by RT-PCR and ELISA, respectively.

RESULTS

F. alocis was highly prevalent in biopsies from periodontitis patients but barely present in the healthy gingiva. Significantly higher MMP-1 expression levels were found in the inflamed gingiva as compared with healthy biopsies. F. alocis caused a significant and dose-dependent MMP-1 upregulation in both cells. The stimulatory effect of F. alocis on MMP-1 was TLR2- and MAPK-dependent and more pronounced on THP-1 cells as compared with HGF-1 cells.

CONCLUSIONS

Our results demonstrate that F. alocis and MMP-1 are more prevalent at periodontitis sites. Additionally, our study provides original evidence that F. alocis can stimulate MMP-1 production by fibroblastic and monocytic cells, suggesting that F. alocis may contribute to periodontal breakdown through MMP-1.

CLINICAL RELEVANCE

F. alocis and MMP-1 are linked to each other and key players in periodontitis, which may have significant implications for future diagnostic and treatment strategies.

Regulation of somatostatin receptor 2 by proinflammatory, microbial and obesity-related signals in periodontal cells and tissues

Background

Periodontitis is a chronic disease characterized by a progressive and irreversible destruction of the tooth-supporting tissues, including gingiva and periodontal ligament (PDL). Microorganisms, such as Fusobacterium nucleatum, evoke an inflammatory host response, which leads to increased levels of inflammatory mediators, such as interleukin (IL)-1β. Periodontitis has been linked to obesity, and adipokines have been suggested to represent a pathomechanistic link. The hormone somatostatin (SST) exerts antiproliferative, antiangiogenetic, proapoptotic, anti-nociceptive and other effects through binding to its receptors, such as SSTR2. Therefore, the objective of the present study was to examine the regulation of SSTR2 in periodontal cells and tissues under inflammatory, microbial and obesity-related conditions.

Methods

In-vitro, human PDL fibroblasts were exposed to IL-1β, F. nucleatum, leptin or visfatin. The SSTR2 regulation was assessed by real-time PCR and immunocytochemistry. In-vivo, the SSTR2 expression was analyzed in gingival biopsies of periodontally diseased and healthy subjects by real-time PCR and immunohistochemistry. Additionally, the SSTR2 expression was determined in gingival biopsies of rats with ligature-induced periodontitis, rats with diet-induced obesity, and periodontally and systemically healthy control animals. For statistical analyses, the Mann-Whitney-U test and ANOVA with post-hoc tests were applied (p < 0.05).

Results

Exposure of PDL cells to IL-1β and F. nucleatum caused a significant SSTR2 upregulation by 2.6-fold and 6.4-fold, respectively. Additionally, leptin and visfatin increased significantly the SSTR2 gene expression by 3.0-fold and 2.8-fold, respectively. These stimulatory effects were also observed at protein level. SSTR2 expressions in human gingival biopsies from sites of periodontitis were significantly higher than those in healthy biopsies. Similarly, SSTR2 expression levels were significantly enhanced at periodontally-diseased sites in rat experimental periodontitis. Finally, the SSTR2 expression was significantly upregulated in gingival biopsies of obese rats as compared to normal weight control animals.

Conclusions

Our study provides original insights into the SSTR2 regulation in cells and tissues of the periodontium. We demonstrate for the first time that proinflammatory, microbial and obesity-associated molecules result in an SSTR2 upregulation. Since SST has been shown to be antiproliferative, antiangiogenetic, and proapoptotic, our study suggests that SSTR2 might play a critical role in the aetiopathogenesis of periodontitis.

Regulation of tyrosine hydroxylase in periodontal fibroblasts and tissues by obesity-associated stimuli

Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the synthesis of catecholamines and has been connected to aggravated progression of periodontal disease under chronic stress. Obesity is known to increase the risk of periodontitis and adipokines have been suggested to be a pathomechanistic link. This study examines if obesity-associated stimuli have regulatory effects on TH levels in periodontal cells and tissues. Human periodontal ligament fibroblasts were cultured in the presence of leptin or visfatin for up to 2 days. Untreated cells served as control. TH regulation was analyzed by real-time PCR, immunocytochemistry and ELISA. TH gene expression in periodontal tissues of normal-weight and obese rodents was determined. Examination of gingival biopsies from rats and patients with and without periodontal disease was performed by real-time PCR or immunohistochemistry. For statistics, ANOVA and post hoc tests were applied (p < 0.05). In vitro, TH gene expression and protein levels were increased by leptin and visfatin. In vivo, TH gene expression was upregulated in periodontal tissues of obese rodents as compared to normal-weight animals. Additionally, increased TH gene expression was found in rat gingival biopsies with experimental periodontitis. Human gingival biopsies from sites of periodontitis confirmed the animal data by demonstrating elevated TH levels at periodontally diseased sites. This study provides original evidence that obesity-associated stimuli induce a TH upregulation in periodontal cells and tissues. Since TH levels were also increased at periodontitis sites, our in vitro and animal findings suggest that this enzyme could represent a pathomechanism whereby obesity contributes to periodontitis.

Characterization of a diet-induced obesity rat model for periodontal research

OBJECTIVES

Obesity is associated with periodontitis, but the mechanisms underlying this association have yet to be unraveled. The present investigation was to evaluate a common rat model, in which obesity is induced by high-fat, high-sucrose diet (HFSD), for its applicability in periodontal research.

MATERIALS AND METHODS

Ten male Wistar rats were fed a 3-month HFSD along with a matching control group. Afterwards, the body weight, adipocyte morphology, leptin and adiponectin levels in adipose tissue, gingiva, and serum as well as the serum levels of triglyceride, cholesterol, and glucose were analyzed. For statistical analyses, parametric and non-parametric tests were applied (p < 0.05).

RESULTS

Body weight was significantly higher in the HFSD group after dieting as compared to control. HFSD caused a significant increase in serum triglyceride, low-density lipoprotein cholesterol, and leptin levels and a significant decrease in high-density lipoprotein cholesterol. Furthermore, adipose tissue from HFSD rats exhibited significantly larger adipocytes, displayed a significant upregulation of leptin and, surprisingly, elevated adiponectin levels, which is in contrast to chronic obesity in humans. Although leptin and adiponectin were also observed in gingival biopsies, no obvious differences between the groups were found.

CONCLUSIONS

Although this rat diet-induced obesity model is characterized by changes typical of obesity, it also has limitations, which have to be considered when data, especially with regard to adipokines, are extrapolated to humans.

CLINICAL RELEVANCE

The rodent diet-induced obesity model may be useful for unraveling pathomechanisms underlying the association between obesity and periodontal destruction but conclusions have to be drawn with caution.

Damage-regulated autophagy modulator 1 in oral inflammation and infection

OBJECTIVES

Damage-regulated autophagy modulator (DRAM) 1 is a p53 target gene with possible involvement in oral inflammation and infection. This study sought to examine the presence and regulation of DRAM1 in periodontal diseases.

MATERIAL AND METHODS

In vitro, human periodontal ligament fibroblasts were exposed to interleukin (IL)-1β and Fusobacterium nucleatum for up to 2 days. The DRAM1 synthesis and its regulation were analyzed by real-time PCR, immunocytochemistry, and ELISA. Expressions of other autophagy-associated genes were also studied by real-time PCR. In vivo, synthesis of DRAM1 in gingival biopsies from rats and patients with and without periodontal disease was examined by real-time PCR and immunohistochemistry. For statistics, ANOVA and post-hoc tests were applied (p < 0.05).

RESULTS

In vitro, DRAM1 was significantly upregulated by IL-1β and F. nucleatum over 2 days and a wide range of concentrations. Additionally, increased DRAM1 protein levels in response to both stimulants were observed. Autophagy-associated genes ATG3, BAK1, HDAC6, and IRGM were also upregulated under inflammatory or infectious conditions. In vivo, the DRAM1 gene expression was significantly enhanced in rat gingival biopsies with induced periodontitis as compared to control. Significantly increased DRAM1 levels were also detected in human gingival biopsies from sites of periodontitis as compared to healthy sites.

CONCLUSION

Our data provide novel evidence that DRAM1 is increased under inflammatory and infectious conditions in periodontal cells and tissues, suggesting a pivotal role of DRAM1 in oral inflammation and infection.

CLINICAL RELEVANCE

DRAM1 might be a promising target in future diagnostic and treatment strategies for periodontitis.

Visfatin expression in gingival tissues of chronic periodontitis and aggressive periodontitis patients: An immunohistochemical analysis

BACKGROUND

Visfatin, also known as nicotinamide phosphoribosyltransferase, has been suggested as a pro-inflammatory and immunomodulating marker for periodontitis. The aim of this study was an immunohistochemical analysis of visfatin in gingival tissues of patients with chronic periodontitis and aggressive periodontitis.

MATERIALS AND METHODS

In this cross-sectional study based on clinical evaluation and inclusion and exclusion criteria. Twenty patients with generalized chronic periodontitis, 13 patients with generalized aggressive periodontitis, and 20 periodontally healthy individuals enrolled. Gingival tissue samples were obtained during periodontal flap surgery and crown lengthening surgery in periodontal patients and healthy group, respectively. Tissue samples were transferred to a pathology laboratory to determine the degree of inflammatory infiltration by hematoxylin and eosin staining and the level of visfatin expression by immunohistochemistry. The data were analyzed using SPSS version 20 statistical software and paired t-test, Mann-Whitney test, and Spearman rank correlation coefficient. P < 0.05 was considered statistically significant.

RESULTS

Inflammation grading and visfatin expression were significantly higher in periodontally diseased gingiva compared to the control group (P < 0.05). However, no significant difference was found between two diseased groups. The relationship between inflammation grading and visfatin expression in aggressive periodontitis group was statistically significant, positive and relatively strong (P = 0.025, r = 0.617). However, no significant relationship has been found between visfatin expression and inflammation grading in the chronic periodontitits and control groups (P > 0.05).

CONCLUSION

Visfatin expression was increased in gingival tissues of chronic periodontitis and aggressive periodontitis patients. Hence, visfatin may have a role in the etiopathogenesis of chronic periodontitis and aggressive periodontitis.

Role of Cathepsin S in Periodontal Inflammation and Infection

Cathepsin S is a cysteine protease and regulator of autophagy with possible involvement in periodontitis. The objective of this study was to investigate whether cathepsin S is involved in the pathogenesis of periodontal diseases. Human periodontal fibroblasts were cultured under inflammatory and infectious conditions elicited by interleukin-1β and Fusobacterium nucleatum, respectively. An array-based approach was used to analyze differential expression of autophagy-associated genes. Cathepsin S was upregulated most strongly and thus further studied in vitro at gene and protein levels. In vivo, gingival tissue biopsies from rats with ligature-induced periodontitis and from periodontitis patients were also analyzed at transcriptional and protein levels. Multiple gene expression changes due to interleukin-1β and F. nucleatum were observed in vitro. Both stimulants caused a significant cathepsin S upregulation. A significantly elevated cathepsin S expression in gingival biopsies from rats with experimental periodontitis was found in vivo, as compared to that from control. Gingival biopsies from periodontitis patients showed a significantly higher cathepsin S expression than those from healthy gingiva. Our findings provide original evidence that cathepsin S is increased in periodontal cells and tissues under inflammatory and infectious conditions, suggesting a critical role of this autophagy-associated molecule in the pathogenesis of periodontitis.

Regulation of Ghrelin Receptor by Periodontal Bacteria In Vitro and In Vivo

Ghrelin plays a major role in obesity-related diseases which have been shown to be associated with periodontitis. This study sought to analyze the expression of the functional receptor for ghrelin (GHS-R1a) in periodontal cells and tissues under microbial conditions in vitro and in vivo. The GHS-R1a expression in human periodontal cells challenged with the periodontopathogen Fusobacterium nucleatum, in gingival biopsies from periodontally healthy and diseased individuals, and from rats with and without ligature-induced periodontitis was analyzed by real-time PCR, immunocytochemistry, and immunofluorescence. F. nucleatum induced an initial upregulation and subsequent downregulation of GHS-R1a in periodontal cells. In rat experimental periodontitis, the GHS-R1a expression at periodontitis sites was increased during the early stage of periodontitis, but significantly reduced afterwards, when compared with healthy sites. In human gingival biopsies, periodontally diseased sites showed a significantly lower GHS-R1a expression than the healthy sites. The expression of the functional ghrelin receptor in periodontal cells and tissues is modulated by periodontal bacteria. Due to the downregulation of the functional ghrelin receptor by long-term exposure to periodontal bacteria, the anti-inflammatory actions of ghrelin may be diminished in chronic periodontal infections, which could lead to an enhanced periodontal inflammation and tissue destruction.

NAMPT serum levels are selectively elevated in acute infectious disease and in acute relapse of chronic inflammatory diseases in children

Nicotinamide phosphoribosyl transferase (NAMPT) is an inflammatory adipocytokine shown to interact in immune modulation in chronic inflammatory diseases, acute respiratory distress syndrome, sepsis, cancer and obesity in adulthood. It is, however, not clear whether this association reflects a chronic elevation or acute inflammatory response. We analyzed NAMPT concentrations in distinct states of inflammation in 102 children and found consistently significantly increased NAMPT levels in subjects with acute infections. NAMPT concentrations in children with stable chronic inflammatory diseases were not significantly different, whereas in patients with acute relapse of chronic disease NAMPT was significantly higher than in children in remission or healthy controls. In states of low-grade inflammation (children with atopic disease or obesity) we did not detect alterations in NAMPT serum levels. NAMPT correlated positively with inflammatory markers such as CRP. The most predictive factor for NAMPT serum concentrations was leucocyte count and therein the neutrophil count. Furthermore, systemic circulating NAMPT levels were closely associated with NAMPT release from corresponding cultured PBMCs. In conclusion, NAMPT is selectively increased in states of acute but not chronic inflammation in children. The close relationship between systemic circulating NAMPT with leucocyte counts and release indicate that leucocytes most probably are the source of inflammation related NAMPT levels.

NAMPT enzyme activity regulates catabolic gene expression in gingival fibroblasts during periodontitis

Periodontal disease is one of the most prevalent chronic disorders worldwide. It is accompanied by inflammation of the gingiva and destruction of periodontal tissues, leading to alveolar bone loss. Here, we focused on the role of adipokines, which are locally expressed by periodontal tissues, in the regulation of catabolic gene expression leading to periodontal inflammation. The expression of the nicotinamide phosphoribosyltransferase (NAMPT) adipokine was dramatically increased in inflamed human and mouse gingival tissues. NAMPT expression was also increased in lipopolysaccharide- and proinflammatory cytokine-stimulated primary cultured human gingival fibroblasts (GF). Adenovirus-mediated NAMPT (Ad-Nampt) overexpression upregulated the expression and activity of COX-2, MMP1 and MMP3 in human GF. The upregulation of IL-1β- or Ad-Nampt-induced catabolic factors was significantly abrogated by the intracellular NAMPT (iNAMPT) inhibitor, FK866 or by the sirtuin (SIRT) inhibitor, nicotinamide (NIC). Recombinant NAMPT protein or extracellular NAMPT (eNAMPT) inhibition using a blocking antibody did not alter NAMPT target gene expression levels. Moreover, intragingival Ad-Nampt injection mediated periodontitis-like phenotypes including alveolar bone loss in mice. SIRT2, a part of the SIRT family, was positively associated with NAMPT actions in human GF. Furthermore, in vivo inhibition of the NAMPT-NAD⁺-SIRT axis by NIC injection in mice ameliorated the periodontal inflammation and alveolar bone erosion caused by intragingival injection of Ad-Nampt. Our findings indicate that NAMPT is highly upregulated in human GF, while its enzymatic activity acts as a crucial mediator of periodontal inflammation and alveolar bone destruction via regulation of COX-2, MMP1, and MMP3 levels.

Assessment of the involvement of the macrophage migration inhibitory factor-glucocorticoid regulatory dyad in the expression of matrix metalloproteinase-2 during periodontitis

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine and counter-regulator of endogenous glucocorticoids (GCs). It is implicated in acute and chronic inflammatory diseases. This study investigated the role of the MIF-GC regulatory dyad in the expression and release of matrix metalloproteinase-2 (MMP-2) during periodontitis, in vivo and in vitro. In a Mif-knockout (KO) mouse model of ligature-induced periodontitis, gingival tissues and blood were collected and analysed for levels of interleukin-6 (IL-6), MIF, MMP-2, and corticosterone. In addition, human gingival fibroblasts (HGFs) were tested for production of IL-6 and MMP-2 after stimulation with hydrocortisone (HC), MIF, tumour necrosis factor-alpha (TNF-α), or Fusobacterium nucleatum, a pathogen known to elicit immune responses during periodontitis. Wild-type (WT) mice showed a local and systemic increase of MIF levels during inflammation, which was confirmed by increased local IL-6 concentrations. Systemic GC levels were reduced in WT and Mif-KO mice during inflammation, with overall lower concentrations in Mif-KO mice. In vivo and in vitro, MMP-2 production was not dependent on MIF or inflammatory stimuli, but was inhibited by HC. Therefore, MIF does not appear to stimulate expression of MMP-2 in the gingival tissues, whereas GC upregulates MIF and downregulates MMP-2. Our findings further suggest that MIF may regulate systemic GC levels.

Inhibition of the MurA enzyme in Fusobacterium nucleatum by potential inhibitors identified through computational and in vitro approaches

Inhibition of MurA in open conformation by orientin and in closed conformation by quercetin-3-O-d-glucuronide with efficient inhibitory constant values.

Genome-wide association study of dental caries in the Hispanic Communities Health Study/Study of Latinos (HCHS/SOL)

Dental caries is the most common chronic disease worldwide, and exhibits profound disparities in the USA with racial and ethnic minorities experiencing disproportionate disease burden. Though heritable, the specific genes influencing risk of dental caries remain largely unknown. Therefore, we performed genome-wide association scans (GWASs) for dental caries in a population-based cohort of 12 000 Hispanic/Latino participants aged 18-74 years from the HCHS/SOL. Intra-oral examinations were used to generate two common indices of dental caries experience which were tested for association with 27.7 M genotyped or imputed single-nucleotide polymorphisms separately in the six ancestry groups. A mixed-models approach was used, which adjusted for age, sex, recruitment site, five principal components of ancestry and additional features of the sampling design. Meta-analyses were used to combine GWAS results across ancestry groups. Heritability estimates ranged from 20-53% in the six ancestry groups. The most significant association observed via meta-analysis for both phenotypes was in the region of the NAMPT gene (rs190395159; P-value = 6 × 10(-10)), which is involved in many biological processes including periodontal healing. Another significant association was observed for rs72626594 (P-value = 3 × 10(-8)) downstream of BMP7, a tooth development gene. Other associations were observed in genes lacking known or plausible roles in dental caries. In conclusion, this was the largest GWAS of dental caries, to date and was the first to target Hispanic/Latino populations. Understanding the factors influencing dental caries susceptibility may lead to improvements in prediction, prevention and disease management, which may ultimately reduce the disparities in oral health across racial, ethnic and socioeconomic strata.

Porphyromonas gingivalis and Epstein-Barr Virus Are Associated With Increased Levels of Visfatin in Gingival Crevicular Fluid

BACKGROUND

There is little clinical information on the relationship between periodontopathogens and visfatin. The purpose of this study is to determine visfatin levels in the gingival crevicular fluid (GCF) of healthy individuals and patients with periodontitis and to investigate the possible relationship between this adipokine and the presence and levels of Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescense, and Epstein-Barr virus (EBV).

METHODS

Eighteen healthy individuals and 27 patients with periodontitis were included in this study. GCF and plaque samples were obtained from all individuals. Visfatin levels were analyzed by enzyme-linked immunosorbent assay, and the bacterial numbers were evaluated by the reverse transcription-polymerase chain reaction method.

RESULTS

In patients with periodontitis, the visfatin levels in the GCF (mean: 84.29 ng/mL; range: 63.8 to 108.9 ng/mL) were significantly higher compared with those of the healthy individuals (mean: 38.06 ng/mL; range: 13.8 to 89.02 ng/mL) (P <0.01). There was a positive correlation between the visfatin levels and P. gingivalis (r = 0.266, P <0.05), whereas no correlation was found between visfatin levels and other microorganisms. In addition, the visfatin levels were found to be higher in individuals in whom P. gingivalis was detected than for those without P. gingivalis (P <0.01). The visfatin levels were also found to be higher in individuals in whom EBV was detected (P <0.05).

CONCLUSIONS

To the best of the authors' knowledge, the present study is the first one to show the correlation of periodontopathogens and GCF visfatin levels. P. gingivalis colonization of the periodontal pockets may increase visfatin secretion. Furthermore, the presence of EBV in the plaque may be another factor that causes an increase in visfatin levels.

Expression of Leptin and Visfatin in Gingival Tissues of Chronic Periodontitis With and Without Type 2 Diabetes Mellitus: A Study Using Enzyme-Linked Immunosorbent Assay and Real-Time Polymerase Chain Reaction

BACKGROUND

The aim of this study is to investigate the protein and gene expression of leptin and visfatin in gingival tissue from patients with chronic periodontitis (CP), patients with CP and type 2 diabetes mellitus (T2DM), and healthy individuals.

METHODS

The study includes 50 individuals: 10 healthy individuals, 20 patients with CP, and 20 patients with CP and T2DM. Plaque index, gingival index, probing depth, and clinical attachment loss were measured, and gingival biopsies were obtained. Leptin and visfatin protein expression in gingival tissues was determined using enzyme-linked immunosorbent assay, and messenger RNA (mRNA) expression was measured via real-time polymerase chain reaction.

RESULTS

The highest leptin mRNA and protein expression was observed in the control group and was significantly (P ≤0.05) different from the CP and CP+T2DM groups. Gingival tissues from patients with CP and T2DM had a significant increase in visfatin and a decrease in leptin gene and protein expression (P <0.05) compared with both controls and patients with CP.

CONCLUSION

Expression of leptin and visfatin in the gingival tissues suggests a possible role for these adipokines in the pathogenesis of CP and T2DM.

The role of adipokines in periodontal infection and healing

Periodontitis is a chronic inflammatory disease of the periodontium, which is caused by pathogenic bacteria in combination with other risk factors. The bacteria induce an immunoinflammatory host response, which can lead to irreversible matrix degradation and bone resorption. Periodontitis can be successfully treated. To achieve regenerative periodontal healing, bioactive molecules, such as enamel matrix derivative (EMD), are applied during periodontal surgery. Recently, it has been shown that obesity is associated with periodontitis and compromised healing after periodontal therapy. The mechanisms underlying these associations are not well understood so far, but adipokines may be a pathomechanistic link. Adipokines are bioactive molecules that are secreted by the adipose tissue, and that regulate insulin sensitivity and energy expenditure, but also inflammatory and healing processes. It has also been demonstrated that visfatin and leptin increase the synthesis of proinflammatory and proteolytic molecules, whereas adiponectin downregulates the production of such mediators in periodontal cells. In addition, visfatin and leptin counteract the beneficial effects of EMD, whereas adiponectin enhances the actions of EMD on periodontal cells. Since visfatin and leptin levels are increased and adiponectin levels are reduced in obesity, these adipokines could be a pathomechanistic link whereby obesity and obesity-related diseases enhance the risk for periodontitis and compromised periodontal healing. Recent studies have also revealed that adipokines, such as visfatin, leptin and adiponectin, are produced in periodontal cells and regulated by periodontopathogenic bacteria. Therefore, adipokines may also represent a mechanism whereby periodontal infections can impact on systemic diseases.

Leptin effects on the regenerative capacity of human periodontal cells

Obesity is increasing throughout the globe and characterized by excess adipose tissue, which represents a complex endocrine organ. Adipose tissue secrets bioactive molecules called adipokines, which act at endocrine, paracrine, and autocrine levels. Obesity has recently been shown to be associated with periodontitis, a disease characterized by the irreversible destruction of the tooth-supporting tissues, that is, periodontium, and also with compromised periodontal healing. Although the underlying mechanisms for these associations are not clear yet, increased levels of proinflammatory adipokines, such as leptin, as found in obese individuals, might be a critical pathomechanistic link. The objective of this study was to examine the impact of leptin on the regenerative capacity of human periodontal ligament (PDL) cells and also to study the local leptin production by these cells. Leptin caused a significant downregulation of growth (TGFβ1, and VEGFA) and transcription (RUNX2) factors as well as matrix molecules (collagen, and periostin) and inhibited SMAD signaling under regenerative conditions. Moreover, the local expression of leptin and its full-length receptor was significantly downregulated by inflammatory, microbial, and biomechanical signals. This study demonstrates that the hormone leptin negatively interferes with the regenerative capacity of PDL cells, suggesting leptin as a pathomechanistic link between obesity and compromised periodontal healing.

Beneficial effects of adiponectin on periodontal ligament cells under normal and regenerative conditions

Type 2 diabetes and obesity are increasing worldwide and linked to periodontitis, a chronic disease which is characterized by the irreversible destruction of the tooth-supporting tissues, that is, periodontium. The mechanisms underlying the association of diabetes mellitus and obesity with periodontal destruction and compromised periodontal healing are not well understood, but decreased plasma levels of adiponectin, as found in diabetic and obese individuals, might be a critical mechanistic link. The aim of this in vitro study was to examine the effects of adiponectin on periodontal ligament (PDL) cells under normal and regenerative conditions, and to study the regulation of adiponectin and its receptors in these cells. Adiponectin stimulated significantly the expression of growth factors and extracellular matrix, proliferation, and in vitro wound healing, reduced significantly the constitutive tumor necrosis factor-α expression, and caused a significant upregulation of its own expression. The beneficial actions of enamel matrix derivative on a number of PDL cell functions critical for periodontal regeneration were partially enhanced by adiponectin. The periodontopathogen Porphyromonas gingivalis inhibited the adiponectin expression and stimulated the expression of its receptors. In conclusion, reduced levels of adiponectin, as found in type 2 diabetes and obesity, may compromise periodontal health and healing.