Inhibition of interleukin 1β-stimulated interleukin-6 production by cranberry components in human gingival epithelial cells: effects on nuclear factor κB and activator protein 1 activation pathways

Polyphenols in Oral Health: Homeostasis Maintenance, Disease Prevention, and Therapeutic Applications

Polyphenols, a class of bioactive compounds with phenolic structures, are abundant in human diets. They have gained attention in biomedical fields due to their beneficial properties, including antioxidant, antibacterial, and anti-inflammatory activities. Therefore, polyphenols can prevent multiple chronic or infectious diseases and may help in the prevention of oral diseases. Oral health is crucial to our well-being, and maintaining a healthy oral microbiome is essential for preventing various dental and systemic diseases. However, the mechanisms by which polyphenols modulate the oral microbiota and contribute to oral health are still not fully understood, and the application of polyphenol products lies in different stages. This review provides a comprehensive overview of the advancements in understanding polyphenols' effects on oral health: dental caries, periodontal diseases, halitosis, and oral cancer. The mechanisms underlying the preventive and therapeutic effects of polyphenols derived from dietary sources are discussed, and new findings from animal models and clinical trials are included, highlighting the latest achievements. Given the great application potential of these natural compounds, novel approaches to dietary interventions and oral disease treatments may emerge. Moreover, investigating polyphenols combined with different materials presents promising opportunities for developing innovative therapeutic strategies in the treatment of oral diseases.

Evaluation of the effects of e-cigarette aerosol extracts and tobacco cigarette smoke extracts on human gingival epithelial cells

Smoking increases the risk of a number of diseases, including cardiovascular, oral and lung diseases. E-cigarettes are gaining popularity among young people as an alternative to cigarettes, but there is debate over whether they are less harmful to the mouth than e-cigarettes. In this study, human gingival epithelial cells (HGECs) were treated with four commercially available e-cigarette aerosol condensates (ECAC) or commercially available generic cigarette smoke condensates (CSC) with different nicotine concentrations. Cell viability was determined by MTT assay. Cell apoptosis was observed by acridine orange (AO) and Hoechst33258 staining. The levels of type I collagen, matrix metalloproteinase (MMP-1, MMP-3), cyclooxygenase 2 and inflammatory factors were detected by ELISA and RT-PCR. Finally, ROS levels were analyzed by ROS staining. The different effects of CSC and ECAC on HGECs were compared. The results showed that higher nicotine concentration of CS significantly reduced the activity of HGECs. By contrast, all ECAC had no significant effect. The levels of matrix metalloproteinase, COX-2, and inflammatory factors were higher in HGECs treated with CSC than those treated with ECAC. In contrast, the level of type I collagen was higher in HGECs treated with ECAC than those treated with CSC. In conclusion, all four flavors of e-cigarettes were less toxic to HGE cells than tobacco, but further clinical studies are needed to determine whether e-cigarettes are less harmful to oral health than conventional cigarettes.

Evaluation of the Effects of E-Cigarette Aerosol Extracts and Tobacco Cigarette Smoke Extracts on Human Gingival Epithelial Cells

Smoking increases the risk of a number of diseases, including cardiovascular, oral, and lung diseases. E-cigarettes are gaining popularity among young people as an alternative to cigarettes, but there is debate over whether they are less harmful to the mouth than e-cigarettes. In this study, human gingival epithelial cells (HGECs) were treated with four commercially available e-cigarette aerosol condensates (ECAC) or commercially available generic cigarette smoke condensates (CSC) with different nicotine concentrations. Cell viability was determined by MTT assay. Cell apoptosis was observed by acridine orange (AO) and Hoechst33258 staining. The levels of type I collagen, matrix metalloproteinase (MMP-1, MMP-3), cyclooxygenase 2, and inflammatory factors were detected by ELISA and RT-PCR. Finally, ROS levels were analyzed by ROS staining. The different effects of CSC and ECAC on HGECs were compared. The results showed that higher nicotine concentration of CS significantly reduced the activity of HGECs. By contrast, all ECAC had no significant effect. The levels of matrix metalloproteinase, COX-2, and inflammatory factors were higher in HGECs treated with CSC than those treated with ECAC. In contrast, the level of type I collagen was higher in HGECs treated with ECAC than those treated with CSC. In conclusion, all four flavors of e-cigarettes were less toxic to HGE cells than tobacco, but further clinical studies are needed to determine whether e-cigarettes are less harmful to oral health than conventional cigarettes.

Modulation of Cytoskeleton, Protein Trafficking, and Signaling Pathways by Metabolites from Cucurbitaceae, Ericaceae, and Rosaceae Plant Families

One promising frontier within the field of Medical Botany is the study of the bioactivity of plant metabolites on human health. Although plant metabolites are metabolic byproducts that commonly regulate ecological interactions and biochemical processes in plant species, such metabolites also elicit profound effects on the cellular processes of human and other mammalian cells. In this regard, due to their potential as therapeutic agents for a variety of human diseases and induction of toxic cellular responses, further research advances are direly needed to fully understand the molecular mechanisms induced by these agents. Herein, we focus our investigation on metabolites from the Cucurbitaceae, Ericaceae, and Rosaceae plant families, for which several plant species are found within the state of Florida in Hillsborough County. Specifically, we compare the molecular mechanisms by which metabolites and/or plant extracts from these plant families modulate the cytoskeleton, protein trafficking, and cell signaling to mediate functional outcomes, as well as a discussion of current gaps in knowledge. Our efforts to lay the molecular groundwork in this broad manner hold promise in supporting future research efforts in pharmacology and drug discovery.

Regulation of interleukin-6 and matrix metalloproteinases syntheses by bioflavonoids and photobiomodulation in human gingival fibroblasts

This study aimed to evaluate the separately effects of bioflavonoids proanthocyanidins, from grape seed extract (GSE) and synthetic naringenin (NA), as well as photobiomodulation (PBM) by low-level laser therapy on interleukin (IL)-6 and matrix metalloproteinases (MMPs) syntheses by human gingival fibroblasts (HGF). For this purpose, a connective tissue exposure (ulceration) model of HGF, stimulated with tumor necrosis factor-alpha (TNF-α), was used. Initially, the highest non-cytotoxic and non-genotoxic concentrations of bioflavonoids were determined by cell viability and micronuclei formation assays. Then, HGF were exposed to different stimuli: culture medium (negative control), dimethyl sulfoxide (DMSO), TNF-α, NA, GSE, TNF-α + NA, TNF-α + GSE, PBM (3 J/cm², 0.025 W, 780 nm), and TNF-α + PBM. Next, IL-6, MMP-2, and MMP-9 syntheses were assessed. The concentration of 10 μg/mL of bioflavonoids increased cell viability at 24 and 48 h and did not present cytotoxic or genotoxic effects on HGF after 24, 48, and 72 h of contact. This concentration was selected for the assessment of bioflavonoids potential in modulating inflammatory mediators. TNF-α exposure enhanced IL-6 (170%), MMP-2 (10%), and MMP-9 (20%) syntheses, while a decrease of MMP-2 by 55% after exposure to TNF-α + GSE and 20% after TNF-α + NA and TNF-α + PBM was observed. MMP-9 synthesis was decreased by 35% after TNF-α + NA, 20% after TNF-α + GSE, and 30% after PBM. IL-6 was down-regulated by GSE in the presence of TNF-α (80%). In conclusion, TNF-α up-regulated IL-6 and MMPs, while bioflavonoids and PBM down-regulated MMP-2 and MMP-9 syntheses; GSE also decreased IL-6 synthesis, demonstrating the individual promising potential of these therapies for ulceration management.

The Effects of Nutraceuticals and Bioactive Natural Compounds on Chronic Periodontitis: A Clinical Review

The paper aims to review the current clinical evidence of various herbal agents as an adjunct treatment in the management of chronic periodontitis patients. Gingivitis and periodontitis are two common infectious inflammatory diseases of the supporting tissues of the teeth and have a multifactorial etiology. An important concern about chronic periodontitis is its association with certain systemic disease. New treatment strategies for controlling the adverse effects of chronic periodontitis have been extensively assessed and practiced in sub-clinical and clinical studies. It has been shown that the phytochemical agents have various therapeutic properties such as anti-inflammatory and antibacterial effects which can be beneficial for the treatment of periodontitis. The findings of this review support the adjunctive use of herbal agents in the management of chronic periodontitis. Heterogeneity and limited data may reduce the impact of these conclusions. Future long-term randomized controlled trials evaluating the clinical efficacy of adjunctive herbal therapy to scaling and root planing are needed.

Effect of cranberry juice deacidification on its antibacterial activity against periodontal pathogens and its anti-inflammatory properties in an oral epithelial cell model

Cranberries are widely recognized as a functional food that can promote oral health. However, the high concentration of organic acids in cranberry juice can cause tooth enamel erosion. Electrodialysis with bipolar membrane (EDBM) is a process used for the deacidification of cranberry juice. The present study investigated whether the removal of organic acids (0%, 19%, 42%, 60%, and 79%) from cranberry juice by EDBM affects its antibacterial activity against major periodontopathogens as well as its anti-inflammatory properties in an oral epithelial cell model. A deacidification rate ≥60% attenuated the bactericidal effect against planktonic and biofilm-embedded Aggregatibacter actinomycetemcomitans but had no impact on Porphyromonas gingivalis and Fusobacterium nucleatum. Cranberry juice increased the adherence of A. actinomycetemcomitans and P. gingivalis to oral epithelial cells, but reduced the adherence of F. nucleatum by half regardless of the deacidification rate. F. nucleatum produced more hydrogen sulfide when it was exposed to deacidified cranberry juice with a deacidification rate ≥42% compared to the raw beverage. Interestingly, the removal of organic acids from cranberry juice lowered the cytotoxicity of the beverage for oral epithelial cells. Deacidification attenuated the anti-inflammatory effect of cranberry juice in an in vitro oral epithelial cell model. The secretion of IL-6 by lipopolysaccharide (LPS)-stimulated oral epithelial cells exposed to cranberry juice increased proportionally with the deacidification rate. No such effect was observed with respect to the production of IL-8. This study provided evidence that organic acids, just like phenolic compounds, might contribute to the health benefits of cranberry juice against periodontitis.

Proanthocyanidins and Flavan-3-ols in the Prevention and Treatment of Periodontitis-Immunomodulatory Effects, Animal and Clinical Studies

This paper continues the systematic review on proanthocyanidins and flavan-3-ols in the prevention and treatment of periodontal disease and covers the immunomodulatory effects, and animal- and clinical studies, while the other part discussed the direct antibacterial properties. Inflammation as a major response of the periodontal tissues attacked by pathogenic microbes can significantly exacerbate the condition. However, the bidirectional activity of phytochemicals that simultaneously inhibit bacterial proliferation and proinflammatory signaling can provide a substantial alleviation of both cause and symptoms. The modulatory effects on various aspects of inflammatory and overall immune response are covered, including confirmed and postulated mechanisms of action, structure activity relationships and molecular targets. Further, the clinical relevance of flavan-3-ols and available outcomes from clinical studies is analyzed and discussed. Among the numerous natural sources of flavan-3-ols and proanthocyanidins the most promising are, similarly to antibacterial properties, constituents of various foods, such as fruits of Vaccinium species, tea leaves, grape seeds, and tannin-rich medicinal herbs. Despite a vast amount of in vitro and cell-based evidence of immunomodulatory there are still only a few animal and clinical studies. Most of the reports, regardless of the used model, indicated the efficiency of these phytochemicals from cranberries and other Vaccinium species and tea extracts (green or black). Other sources such as grape seeds and traditional medicinal plants, were seldom. In conclusion, the potential of flavan-3-ols and their derivatives in prevention and alleviation of periodontal disease is remarkable but clinical evidence is urgently needed for issuing credible dietary recommendation and complementary treatments.

Effects of 1,25-dihydroxyvitamin D3 on experimental periodontitis and AhR/NF-κB/NLRP3 inflammasome pathway in a mouse model

Vitamin D has been known to have important regulatory functions in inflammation and immune response and shows inhibitory effects on experimental periodontitis in animal models. However, the potential mechanism has yet to be clarified. Recent studies have highlighted Aryl hydrocarbon receptor (AhR) and its downstream signaling as a crucial regulator of immune homeostasis and inflammatory regulation.

OBJECTIVE

This study aimed to clarify the effect of 1,25-dihydroxyvitamin D3 (VD3) on experimental periodontitis and AhR/nuclear factor-κB (NF-κB)/NLR pyrin domain-containing 3 (NLRP3) inflammasome pathway in the gingival epithelium in a murine model.

METHODOLOGY

We induced periodontitis in male C57BL/6 wild-type mice by oral inoculation of Porphyromonas gingivalis (P. gingivalis), and subsequently gave intraperitoneal VD3 injection to the mice every other day for 8 weeks. Afterwards, we examined the alveolar bone using scanning electron microscopy (SEM) and detected the gingival epithelial protein using western blot analysis and immunohistochemical staining.

RESULTS

SEM images demonstrated that alveolar bone loss was reduced in the periodontitis mouse model after VD3 supplementation. Western blot analyses and immunohistochemical staining of the gingival epithelium showed that the expression of vitamin D receptor, AhR and its downstream cytochrome P450 1A1 were enhanced upon VD3 application. Additionally, VD3 decreased NF-κB p65 phosphorylation, and NLRP3, apoptosis-associated speck-like protein, caspase-1, interleukin-1β (IL-1β) and IL-6 protein expression.

CONCLUSIONS

These results implicate the alleviation of periodontitis and the alteration of AhR/NF-κB/NLRP3 inflammasome pathway by VD3 in the mouse model. The attenuation of this periodontal disease may correlate with the regulation of AhR/NF-κB/NLRP3 inflammasome pathway by VD3.

Polyphenols in the prevention and treatment of periodontal disease: A systematic review of in vivo, ex vivo and in vitro studies

Plant-derived polyphenols with antimicrobial and immunomodulatory characteristics appear to provide a variety of oral health benefits. Thus, the aim of the present study was to review the scientific literature to identify these effects of polyphenols on periodontal pathogens and inflammation. A MEDLINE search from 1st January 2013 to 18th January 2018 was performed to identify studies reporting polyphenol-containing plant extracts. Reports regarding pure compounds and essential oils, as well as effects on bacteria that are not defined as periodontal pathogens, were excluded. Thirty-eight studies matched the selection criteria. Studies on immunomodulatory effects included in vitro, ex vivo, and in vivo studies (n = 23), whereas studies reporting antibacterial effects against periodontal pathogens included only in vitro studies (n = 18). Three studies were included in both groups. The antibacterial effects were characterised by inhibition of bacterial growth, adhesion to oral cells, and enzymatic activity. Decreased secretion of pro-inflammatory and increased secretion of anti-inflammatory cytokines were demonstrated. Higher attachment levels, lower inflammation, and bone loss were reported by in vivo studies. Due to the high heterogeneity, it is difficult to draw clear conclusions for applicability; nevertheless, polyphenols have great potential as antimicrobial and immunomodulatory substances in the treatment and prevention of periodontal disease.

Effect of 1,25(OH)2 D3 and 20(OH)D3 on interleukin-1β-stimulated interleukin-6 and -8 production by human gingival fibroblasts

BACKGROUND AND OBJECTIVE

Vitamin D-1,25(OH)₂ D₃ or 1,25D3-maintains healthy osseous tissue, stimulates the production of the antimicrobial peptide cathelicidin and has anti-inflammatory effects, but it can cause hypercalcemia. Evidence links diminished serum levels of 1,25D3 with increased gingival inflammation. Periodontitis progression is associated with increased local production of inflammatory mediators by immune cells and gingival fibroblasts. These include interleukin (IL)-6, a regulator of osteoclastic bone resorption, and the neutrophil chemoattractant IL-8, both regulated by signaling pathways, including NF-κB and MAPK/AP-1. The objectives were to determine the effects of 1,25D3 or a non-calcemic analog, 20-hydroxyvitamin D₃ -20(OH)D₃ or 20D3-on IL-1β-stimulated IL-6 and IL-8 production, and NF-κB and MAPK/AP-1 activation, by human gingival fibroblasts.

MATERIAL AND METHODS

Human gingival fibroblasts were incubated ± IL-1β, with or without exposure to 1,25D3 or 20D3. IL-6 and IL-8 in culture supernatants were measured by enzyme-linked immunosorbent assay. NF-κB (p65) and AP-1 (phospho-cJun) and were measured in nuclear extracts via binding to specific oligonucleotides. Data were analyzed using ANOVA and Scheffe's F procedure for post hoc comparisons.

RESULTS

IL-1β-stimulated IL-6 and IL-8 levels were both significantly inhibited (40%-60%) (P<.045) by 1,25D3, but not 20D3 (0%-15% inhibition, not statistically significant). Both 1,25D3 and 20D3 significantly and similarly inhibited IL-1β-stimulated nuclear levels of p65 and phospho-cJun (P<.02).

CONCLUSION

Reduction of the activation of NF-κB and AP-1 alone is not able to inhibit strongly the IL-1β stimulated IL-6 and IL-8 gene expression. 1,25D3 but not 20D3 may affect some of the many other factors/processes/pathways that in turn regulate the expression of these genes. However, the results suggest that topical application of ligands of the vitamin D receptor may be useful in the local treatment of periodontitis while reducing adverse systemic effects.

Effect of glycated albumin and cranberry components on interleukin-6 and matrix metalloproteinase-3 production by human gingival fibroblasts

BACKGROUND AND OBJECTIVE

Gingival fibroblasts have the potential to participate in periodontal inflammation and breakdown, producing interleukin (IL)-6 and matrix metalloproteinase (MMP)-3. Advanced glycation end products (AGEs), formed during diabetic hyperglycemia, might aggravate periodontal inflammation. The cranberry contains anti-inflammatory polyphenols, which inhibit proinflammatory activities of lipopolysaccharide (LPS)- and IL-1β-stimulated human cells. Little is known of its effects on gingival fibroblast IL-6 or MMP-3 production stimulated by AGEs. The objectives were to determine cranberry effects on IL-6 and MMP-3 production by gingival fibroblasts exposed to the representative AGE, glycated human serum albumin (G-HSA), or LPS ± G-HSA.

MATERIAL AND METHODS

Cranberry high molecular weight non-dialyzable material (NDM), was derived from cranberry juice. Normal human gingival fibroblasts were incubated with G-HSA or normal HSA or Porphyromonas gingivalis LPS (1 μg/mL) ± G-HSA, in the presence or absence of preincubation with NDM. IL-6 and MMP-3 were measured by enzyme-linked immunosorbent assay. Data were analyzed using one-way analysis of variance and Scheffe's F procedure.

RESULTS

IL-6 production was stimulated by G-HSA or LPS (p < 0.01), which was inhibited in both cases by NDM (p < 0.002). [G-HSA+LPS] synergistically stimulated IL-6 production (p < 0.0001), which was inhibited by NDM. MMP-3 levels were not stimulated by G-HSA but were decreased by LPS (p < 0.02). [G-HSA+LPS] increased MMP-3 production significantly, vs. LPS (p = 0.0005). NDM inhibited MMP-3 levels in the presence of G-HSA or LPS, and in the presence of [G-HSA+LPS] (p < 0.0001).

CONCLUSIONS

G-HSA ± LPS may have differential effects on IL-6 and MMP-3 production by human gingival fibroblasts, but both are inhibited by NDM. The study suggests that cranberry phenols may be useful in regulating the host response and perhaps treating periodontitis in patients with poorly controlled diabetes.