A diet rich in omega-3 fatty acid improves periodontitis and tissue destruction by MMP2- and MMP9-linked inflammation in a murine model.

Periodontitis is an oral-cavity inflammatory disease and is the principal cause associated with tooth loss. Matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) are important proteases involved in periodontal tissue destruction. The omega-3 polyunsaturated fatty acids (ω-3 PUFA) have been demonstrated to possess immunoregulatory properties in periodontitis. The aim of the study was to investigate the effects of ω-3 PUFA on inflammation and on the expression of MMP-2 and -9 in a murine periodontitis model. Twenty-four male C57BL/6 mice were divided into control mice (Control), control mice treated with ω-3 PUFA (O3), mice with periodontitis (P), and mice with periodontitis treated with ω-3 PUFA (P + O3). ω-3 PUFA were administered orally once a day for 70 days. Periodontitis in mice was induced by Porphyromonas gingivalis-infected ligature placement around the second maxillary molar. The mice were sacrificed, and blood and maxillary samples were collected. Flow cytometry was used to quantify tumor necrosis factor-alpha (TNFα), interleukin (IL)-2, IL-4, IL-5, and interferon-gamma. Histologic analysis and immunohistochemistry for MMP-2 and -9 were performed. The data were statistically evaluated using analysis of variance (ANOVA) and the Tukey post hoc test. Histological analysis showed that ω-3 PUFA supplementation prevented inflammation and tissue destruction and revealed that bone destruction was more extensive in the P group than in the P + O3 group (p < 0.05). Also, it decreased the serum expressions of TNFα and IL-2 and the tissue expression of MMP-2 and -9 in the periodontitis-induced model (p < 0.05). ω-3 PUFA supplementation prevented alveolar bone loss and periodontal destruction, probably by decreasing the expression of MMP-2 and MMP-9 and its immunoregulatory properties.

The effect of the Litcubanine A on the treatment of murine experimental periodontitis by inhibiting monocyte-macrophage chemotaxis and osteoclast differentiation.

BACKGROUND: Periodontal disease is an inflammatory disease of periodontal tissues that is closely connected with systemic diseases. During periodontitis, the inappropriate recruitment and activation of monocytes-macrophages causes an increase in osteoclast activity and disrupts bone homeostasis. Therefore, it is a promising therapeutic strategy to treat periodontitis by regulating the functions of monocytes-macrophages. Litcubanine A (LA) is an isoquinoline alkaloid extracted from the traditional Chinese medicine Litsea cubeba, which was proven to have reproducible anti-inflammatory effects, but its regulatory role on bone homeostasis in periodontitis is still not clear. METHODS: In this study, zebrafish experiments and a mouse ligature-induced periodontitis model were performed, and histological analysis was used to investigate the effect of LA on macrophage chemotaxis under the inflammatory environment. Real-time PCR was used to detect the regulatory effect of LA (100 nM ~ 100 µM) on the chemotaxis function of macrophages induced by LPS. Apoptosis assay and flow cytometry were used to elucidate the influence of LA on macrophage apoptosis and proliferation. To further clarify the regulatory role of LA on macrophage osteoclast differentiation, real-time PCR, histological analysis, western blot, and micro-computed tomography (micro-CT) were performed in vivo and in vitro to verify the impact of LA on bone homeostasis. RESULTS: Compared with the control group, the chemotaxis function of macrophage was significantly attenuated by LA in vivo. LA could significantly inhibit the expression of genes encoding the chemokine receptors Ccr1 and Cxcr4, and its ligand chemokine Cxcl12 in macrophages, and suppresses the differentiation of osteoclastic precursors to osteoclasts through the MAPK signaling pathway. There were significantly lower osteoclast differentiation and bone loss in the LA group compared with the control in the ligature-induced periodontitis model. CONCLUSION: LA is a promising candidate for the treatment of periodontitis through its reproducible functions of inhibiting monocyte-macrophage chemotaxis and osteoclast differentiation.

Relevant mechanisms of MAIT cells involved in the pathogenesis of periodontitis.

Mucosal-associated invariant T (MAIT) cells are a group of unconventional T cells that are abundant in the human body, recognize microbial-derived vitamin B metabolites presented by MHC class I-related protein 1 (MR1), and rapidly produce proinflammatory cytokines, which are widely involved in the immune response to various infectious diseases. In the oral mucosa, MAIT cells tend to accumulate near the mucosal basal lamina and are more inclined to secrete IL-17 when activated. Periodontitis is a group of diseases that manifests mainly as inflammation of the gums and resorption of the alveolar bone due to periodontal tissue invasion by plaque bacteria on the dental surface. The course of periodontitis is often accompanied by a T-cell-mediated immune response. This paper discussed the pathogenesis of periodontitis and the potential contribution of MAIT cells to periodontitis.

Periodontal treatment and microbiome-targeted therapy in management of periodontitis-related nonalcoholic fatty liver disease with oral and gut dysbiosis.

A growing body of evidence from multiple areas proposes that periodontal disease, accompanied by oral inflammation and pathological changes in the microbiome, induces gut dysbiosis and is involved in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). A subgroup of NAFLD patients have a severely progressive form, namely nonalcoholic steatohepatitis (NASH), which is characterized by histological findings that include inflammatory cell infiltration and fibrosis. NASH has a high risk of further progression to cirrhosis and hepatocellular carcinoma. The oral microbiota may serve as an endogenous reservoir for gut microbiota, and transport of oral bacteria through the gastro-intestinal tract can set up a gut microbiome dysbiosis. Gut dysbiosis increases the production of potential hepatotoxins, including lipopolysaccharide, ethanol, and other volatile organic compounds such as acetone, phenol and cyclopentane. Moreover, gut dysbiosis increases intestinal permeability by disrupting tight junctions in the intestinal wall, leading to enhanced translocation of these hepatotoxins and enteric bacteria into the liver through the portal circulation. In particular, many animal studies support that oral administration of Porphyromonas gingivalis, a typical periodontopathic bacterium, induces disturbances in glycolipid metabolism and inflammation in the liver with gut dysbiosis. NAFLD, also known as the hepatic phenotype of metabolic syndrome, is strongly associated with metabolic complications, such as obesity and diabetes. Periodontal disease also has a bidirectional relationship with metabolic syndrome, and both diseases may induce oral and gut microbiome dysbiosis with insulin resistance and systemic chronic inflammation cooperatively. In this review, we will describe the link between periodontal disease and NAFLD with a focus on basic, epidemiological, and clinical studies, and discuss potential mechanisms linking the two diseases and possible therapeutic approaches focused on the microbiome. In conclusion, it is presumed that the pathogenesis of NAFLD involves a complex crosstalk between periodontal disease, gut microbiota, and metabolic syndrome. Thus, the conventional periodontal treatment and novel microbiome-targeted therapies that include probiotics, prebiotics and bacteriocins would hold great promise for preventing the onset and progression of NAFLD and subsequent complications in patients with periodontal disease.

Electroacupuncture regulates macrophage, neutrophil, and oral microbiota to alleviate alveolar bone loss and inflammation in experimental ligature-induced periodontitis.

AIM: Electroacupuncture (EA) regulates distant body physiology through somatic sensory autonomic reflexes, balances the microbiome, and can promote the release of immune cells into bloodstream, thereby inhibiting severe systemic inflammation. This makes it possible to use EA as an integrated treatment for periodontitis. MATERIALS AND METHODS: In this study, EA was applied to the ST36 acupoints in a ligature-induced periodontitis (LIP) mouse model. Then the effects of EA on periodontal myeloid cells, cytokines, and the microbiome were comprehensively analysed using flow cytometry, quantitative Polymerase Chain Reaction (PCR), and 16 S sequencing. RESULTS: Results demonstrated that EA could significantly relieve periodontal bone resorption. EA also suppressed the infiltration of macrophages and neutrophils, reduced gene expression of the pro-inflammatory cytokines IL-1ß, IL-6, IL-17 and TNF-α, and increased expression of the anti-inflammatory factors IL-4 and IL-10 in periodontal tissues. Moreover, composition of the periodontal microbiome was regulated by EA, finding that complex of microbiota, including supragingival Veillonella, subgingival Streptococcus, and subgingival Erysipelatoclostridium, were significantly reduced. Meanwhile, nitrate and nitrate-related activities of subgingival microbiota were reversed. Network analysis revealed close relationships among Veillonella, Streptococcus, and Bacteroides. CONCLUSIONS: Our study indicates that EA can effectively alleviate inflammation and bone resorption in LIP mice, potentially via the regulation of myeloid cells, cytokines, and periodontal microbiome.

D-mannose alleviated alveolar bone loss in mice with experimental periodontitis via regulating the anti-inflammatory effect of amino acids.

BACKGROUND: Periodontitis is a chronic infectious disease caused by dysbiosis of oral microbiota, ultimately leading to periodontal alveolar bone loss. The oral subgingival microbiome, a key role in periodontitis pathogenesis, could alter the composition of gut microbiomes resulting in intestinal microbiota disorder. D-mannose plays an important role in glucose metabolism; whether it is beneficial to prevention and treatment of periodontitis and the regulation of oral and intestinal microbiota changes is still unknown. METHODS: To explore the effect of D-mannose, we established experimental periodontitis models in mice and then treated with supplementation of D-mannose in drinking water or gavage to examine the extent of periodontal bone loss using methylene blue staining. Moreover, the oral and fecal samples of mice were collected for 16S rRNA deep sequencing to analyze the changes of oral and gut microbiota after 14 days. Furthermore, amino acid content assays were used to test the concentration of amino acid of gingival tissues and intestinal tissues. RESULTS: We found that D-mannose could alleviate periodontal bone loss whether in the manner of drinking water or gavage. 16S rRNA results revealed that the abundance of Firmicutes changed significantly in oral samples, while Firmicutes and Akkermansia muciniphila were dominated in gut microbiota. In addition, we demonstrated that D-mannose inhibited inflammation and alleviated alveolar bone loss in periodontitis via regulating amino acid metabolism of oral and gut microbiomes. CONCLUSION: Our findings provided insight into the mechanism underlying the abilities of D-mannose in improving periodontitis treatment, suggesting that D-mannose has potential application in the dental clinic.

Omega-3 Effects on Ligature-Induced Periodontitis in Rats with Fructose-Induced Metabolic Syndrome.

Both periodontal disease (PD) and metabolic syndrome (MS) represent disorders of concern worldwide. Current evidence indicates that PD and MS might negatively influence each other, increasing the risk for cardiovascular diseases (CVD), via mutual inflammatory pathways. A failure of the inflammation resolution mechanisms is crucial for these comorbidities. Fish oil-derived omega-3 has been linked with resolution-driven responses in different pathological conditions during the last years. This study evaluated the impacts of omega-3 supplementation in a rat model combining ligature-induced PD and 10% fructose intake-elicited MS. Our main findings show that 10% fructose ingestion led to an elevation of Lee index and white adipose tissue (WAT) weight, along with hepatic alterations, accompanied by an increase of leptin, and a decrement of adiponectin serum amounts, regardless of PD induction. Noteworthy, the co-induction of PD and MS resulted in higher levels of glycemia and triglycerides, being this latter effect lessened by omega-3 supplementation. In this case, the beneficial effects of omega-3 might be associated with its ability to recover the decline of serum adiponectin levels in rats with PD plus MS. As expected, PD induction led to alveolar bone loss, independent of MS induction. However, the supplementation with omega-3 restored alveolar bone in PD control animals, but not in the rats with PD combined with MS. Our study extends the knowledge about PD and MS as comorbidities, showing novel effects of omega-3 supplementation in this context.

The changes and potential effects of zinc homeostasis in periodontitis microenvironment.

Zinc is a very important and ubiquitous element, which is present in oral environment, daily diet, oral health products, dental restorative materials, and so on. However, there is a lack of attention to the role of both extracellular or intracellular zinc in the progression of periodontitis and periodontal regeneration. This review summarizes the characteristics of immunological microenvironment and host cells function in several key stages of periodontitis progression, and explores the regulatory effect of zinc during this process. We find multiple evidence indicate that zinc may be involved and play a key role in the stages of immune defense, inflammatory response and bone remodeling. Zinc supplementation in an appropriate dose range or regulation of zinc transport proteins can promote periodontal regeneration by either enhancing immune defense or up-regulating local cells proliferation and differentiation functions. Therefore, zinc homeostasis is essential in periodontal remodeling and regeneration. More attention is suggested to be focused on zinc homeostasis regulation and consider it as a potential strategy in the studies on periodontitis treatment, periodontal-guided tissue regeneration, implant material transformation, and so on.

Vitamin C and Omega-3 Fatty Acid Intake Is Associated with Human Periodontitis-A Nested Case-Control Study.

Vitamins and omega-3 fatty acids (Ω3FA) modulate periodontitis-associated inflammatory processes. The aim of the current investigation was to evaluate associations of oral nutrient intake and corresponding serum metabolites with clinical severity of human periodontitis. Within the Food Chain Plus cohort, 373 periodontitis patients­245 without (POL) and 128 with tooth loss (PWL)­were matched to 373 controls based on sex, smoking habit, age and body mass index in a nested case-control design. The amount of oral intake of vitamins and Ω3FAs was assessed from nutritional data using a Food Frequency Questionnaire. Oral intake and circulatory bioavailability of vitamins and Ω3FA serum metabolomics were compared, using ultra-high-resolution mass spectrometry. Periodontitis patients exhibited a significantly higher oral intake of vitamin C and Ω3FA Docosapentaenoic acid (p < 0.05) compared to controls. Nutritional intake of vitamin C was higher in PWL, while the intake of Docosapentaenoic acid was increased in POL (p < 0.05) compared to controls. In accordance, serum levels of Docosapentaenoic acid were also increased in POL (p < 0.01) compared to controls. Vitamin C and the Ω3FA Docosapentaenoic acid might play a role in the pathophysiology of human periodontitis. Further studies on individualized nutritional intake and periodontitis progression and therapy are necessary.

A brief review of vitamin D as a potential target for the regulation of blood glucose and inflammation in diabetes-associated periodontitis.

Diabetes is a metabolic disorder associated with various complications, including periodontitis. The risk of periodontitis is increased in patients with diabetes, while vitamin D deficiency is associated with both diabetes and periodontitis. Thus, there is a need to identify the molecular effects of vitamin D on the regulation of inflammation and glucose in diabetes-associated periodontitis. The Web of Science, Scopus, and PubMed databases were searched for studies of the molecular effects of vitamin D. Molecular effects were reportedly mediated by salivary secretions, interactions of advanced glycation end products (AGEs) with receptors of AGEs (RAGEs), cytokines, and oxidative stress pathways linking diabetes with periodontitis. Vitamin D supplementation attenuates inflammation in diabetes-associated periodontitis by reducing the levels of inflammatory cytokines and numbers of immune cells; it also has antibacterial effects. Vitamin D reduces cytokine levels through regulation of the extracellular signal-related kinase 1/2 and Toll-like receptor 1/2 pathways, along with the suppression of interleukin expression. Glucose homeostasis is altered in diabetes either because of reduced insulin production or decreased insulin sensitivity. These vitamin D-related alterations of glucoregulatory factors may contribute to hyperglycaemia; hyperglycaemia may also lead to alterations of glucoregulatory factors. This review discusses the pathways involved in glucose regulation and effects of vitamin D supplementation on glucose regulation. Further studies are needed to characterise the effects of vitamin D on diabetes-associated periodontitis.

Anti-Inflammatory and Protective Effects of Juncus effusus L. Water Extract on Oral Keratinocytes.

Periodontitis is a chronic inflammatory disease caused by periodontopathogenic bacteria that form biofilms in periodontal pockets. The gingival epithelium acts as the first physical barrier in fighting attacks by periodontopathogenic pathogens, such as the primary etiological agent Porphyromonas gingivalis, and various exogenous chemicals, as well as regulates the local innate immune responses. Therefore, the development of novel oral care products to inhibit inflammatory reactions caused by bacterial infection and protect the gingival epithelium is necessary. Juncus effusus L. has generally been used as an indigenous medicine, such as a diuretic, an antipyretic, and an analgesic, in ancient practice. In this study, we examined the effects of a water extract from J. effusus L. on the inhibition of the inflammatory reaction elicited by bacterial infection and protection of the oral epithelium by chemical irritation. Pretreatment of oral epithelial cells with the water extract from J. effusus L. significantly reduced P. gingivalis or its lipopolysaccharide- (LPS-) mediated production of chemokines (interleukin-8 and C-C-chemokine ligand20) in a concentration-dependent manner with comparable to or greater effects than epigallocatechin gallate and protected oral epithelial cells from injury by chemical irritants, cetylpyridinium chloride, and benzethonium chloride. Moreover, the water extract from J. effusus L. in the presence of antimicrobial agents or antifibrinolytics already used as ingredients in mouthwash could significantly reduce the production of chemokines from P. gingivalis LPS-stimulated oral epithelial cells in a concentration-dependent manner. These findings suggest that the water extract from J. effusus L. is potentially useful for oral care to prevent oral infections, such as periodontal infections, and maintain oral epithelial function.

Berberine as a promising natural compound for the treatment of periodontal disease: A focus on anti-inflammatory properties.

Accumulating evidence during the last two decades has addressed the potential anti-inflammatory properties of berberine (BBR), a bioactive alkaloid compound isolated from Coptidis rhizoma, in controlling or treating several inflammatory diseases. Periodontitis is one of the most common chronic and serious inflammatory diseases, in which uncontrolled and unabated host immune responses against periodontopathic pathogens play critical and crucial roles in the disease pathogenesis. Hence, regulating inflammatory responses in periodontitis has a valuable approach and holds promise in treating periodontitis. For the first time, this paper reviews the evidence from in vitro and in vivo experimental models to explore the anti-inflammatory effects of BBR in periodontitis and exhibits that BBR has the high potency to exert anti-inflammatory effects by reducing expression and secretion of pro-inflammatory mediators including TNF-α, IL-1ß, IL-17, RANKL, MMP-2, MMP-9 and MCP-1. The BBR-mediated anti-inflammatory actions could translate into the inhibition of the periodontal tissues and alveolar bone destruction and the control of the disease in vivo. As the second aim of this paper, we also paid attention to the therapeutic potential of BBR in treating human diseases regarding its anti-inflammatory properties.

Porphyromonas gingivalis induces entero-hepatic metabolic derangements with alteration of gut microbiota in a type 2 diabetes mouse model.

Periodontal infection induces systemic inflammation; therefore, aggravating diabetes. Orally administered periodontal pathogens may directly alter the gut microbiota. We orally treated obese db/db diabetes mice using Porphyromonas gingivalis (Pg). We screened for Pg-specific peptides in the intestinal fecal specimens and examined whether Pg localization influenced the intestinal microbiota profile, in turn altering the levels of the gut metabolites. We evaluated whether the deterioration in fasting hyperglycemia was related to the changes in the intrahepatic glucose metabolism, using proteome and metabolome analyses. Oral Pg treatment aggravated both fasting and postprandial hyperglycemia (P < 0.05), with a significant (P < 0.01) increase in dental alveolar bone resorption. Pg-specific peptides were identified in fecal specimens following oral Pg treatment. The intestinal Pg profoundly altered the gut microbiome profiles at the phylum, family, and genus levels; Prevotella exhibited the largest increase in abundance. In addition, Pg-treatment significantly altered intestinal metabolite levels. Fasting hyperglycemia was associated with the increase in the levels of gluconeogenesis-related enzymes and metabolites without changes in the expression of proinflammatory cytokines and insulin resistance. Oral Pg administration induced gut microbiota changes, leading to entero-hepatic metabolic derangements, thus aggravating hyperglycemia in an obese type 2 diabetes mouse model.

IL-8 as a Potential Therapeutic Target for Periodontitis and Its Inhibition by Caffeic Acid Phenethyl Ester In Vitro.

Salivary levels of interleukin-8 (IL-8) are elevated in patients with periodontitis. Caffeic acid phenethyl ester (CAPE) improves the periodontal status in subjects. However, whether CAPE can reduce IL-8 expression is unclear. We collected saliva to determine proinflammatory cytokine levels and used subgingival calculus and surrounding tissues from patients with periodontitis for oral microbiota analysis via 16s ribosomal RNA gene sequencing. THP-1 cells were stimulated with sterile-filtered saliva from patients, and target gene/protein expression was assessed. IL-8 mRNA expression was analyzed in saliva-stimulated THP-1 cells treated with CAPE and the heme oxygenase-1 (HO-1) inhibitor tin-protoporphyrin (SnPP). In 72 symptomatic individuals, IL-8 was correlated with periodontal inflammation (bleeding on probing, r = 0.45; p < 0.001) and disease severity (bleeding on probing, r = 0.45; p < 0.001) but not with the four oral microbiota species tested. Reduced salivary IL-8 secretion was correlated with effective periodontitis treatment (r = 0.37, p = 0.0013). In THP-1 cells, saliva treatment induced high IL-8 expression and IKK2 and nuclear factor-κB (NF-κB) phosphorylation. However, the IKK inhibitor BMS-345541, NF-κB inhibitor BAY 11-7082, and CAPE attenuated saliva-induced IL-8 expression. CAPE induced HO-1 expression and inhibited IKK2, IκBα, and NF-κB phosphorylation. Blocking HO-1 decreased the anti-inflammatory activity of CAPE. The targeted suppression of IL-8 production using CAPE reduces inflammation and 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 a tart cherry (Prunus cerasus L.) phenolic extract on Porphyromonas gingivalis and its ability to impair the oral epithelial barrier.

Periodontal diseases, including gingivitis and periodontitis, are a global oral health problem. Porphyromonas gingivalis, a key pathogen involved in the onset of periodontitis, is able to colonize the subgingival epithelium and invade the underlying connective tissue due to the contribution of cysteine proteases known as gingipains. In this study, we investigated the effects of a phenolic extract prepared from tart cherry (Prunus cerasus L.) juice on the growth, adherence, and protease activity of P. gingivalis. We also assessed the protective effect of the tart cherry extract on the disruption of the oral epithelial barrier induced by P. gingivalis. The tart cherry extract that contains procyanidins and quercetin and its derivatives (rutinoside, glucoside) as the most important phenolic compounds attenuated P. gingivalis growth, reduced adherence to an experimental basement membrane matrix model, and decreased the protease activities of P. gingivalis. The tart cherry extract also exerted a protective effect on the integrity of the oral epithelial barrier in an in vitro model infected with P. gingivalis. More specifically, the extract prevented a decrease in transepithelial electrical resistance as well as the destruction of tight junction proteins (zonula occludens-1 and occludin). These results suggest that the tart cherry phenolic extract may be a promising natural product for the treatment of periodontitis through its ability to attenuate the virulence properties of P. gingivalis and curtail the ability of this pathogen to impair the oral epithelial barrier.

Spirulina maxima reduces inflammation and alveolar bone loss in Porphyromonas gingivalis-induced periodontitis.

BACKGROUND: Periodontitis is a common oral disease characterized as inflammation on gingival tissue and alveolar bone resorption. Spirulina maxima has been reported to have anti-oxidative and anti-inflammatory effects on gastric ulcers. However, its effects on gingival inflammation and alveolar bone resorption of periodontitis have not been studied. PURPOSE: This study was designed to investigate the effects of S. maxima on the P. gingivalis-induced periodontitis and to elucidate its mechanism. METHODS: The phycocyanin contents in S. maxima were identified by high-performance liquid chromatography. 8-week old SD rats were induced periodontitis by inoculation with P. gingivalis for 14 days. The rats were then orally treated with S. maxima 100, 200, 400 mg/kg, or indomethacin (IND, positive control) 5 mg/kg for an additional 14 days. Inflammatory responses, expressions of collagenases in gingival tissue, osteoclast formation and activation, alveolar bone resorption, osteogenesis-related markers, and BMP2/Smad signaling in alveolar bone were measured. RESULTS: Pro-inflammatory cytokines such as TNF-α, IL-1ß, IL-6, and inflammatory transcription factor NF-κB were decreased in gingival tissue by S. maxima administration. Also, myeloperoxidase (MPO) activity and matrix metalloproteinase (MMPs) expression were decreased by S. maxima administration. Conversely, S. maxima increased IL-4, anti-inflammatory cytokine from Th2 cells. The osteoprotegerin (OPG) / receptor activator of NF-κB ligand (RANKL) expression ratio, which represents osteoclast-osteoblast balance, was increased in S. maxima-treated groups. The alveolar bone loss and the number of TRAP-positive osteoclast cells were also declined in S. maxima-treated groups while the osteoblasts count was increased. Besides, in S. maxima-treated groups, the osteogenesis-related factors were promoted and BMP-2/Smad pathway was up-regulated in a periodontitis condition. CONCLUSION: S. maxima reduces periodontitis induced by P. gingivalis through anti-inflammatory effect and resultant reduction in bone loss, suggesting that S. maxima might be a potential agent for treating periodontitis.

Electroacupuncture Reduces Inflammation but Not Bone Loss on Periodontitis in Arthritic Rats.

Periodontitis and rheumatoid arthritis (RA) are inflammatory diseases characterized by chronic inflammation and bone erosion. Electroacupuncture (EA) shows anti-inflammatory and anti-resorptive effects in experimental periodontitis (EP) and in RA. It is important to investigate whether EA shows these effects in periodontal tissues in the presence of these two inflammatory diseases or not. For this, Wistar rats were divided into six groups: control (C); experimental rheumatoid arthritis (RA; bovine type II collagen-induced (CII)); experimental periodontitis (EP); RA/EP (RA + EP); EP/EA (EP treated with EA); RA/EP/EA (RA + EP treated with EA). EP was induced 21 days after RA induction and EA was performed previously and during the EP induction period, every 3 days until the 36th experimental day. The rats were euthanized on day 39. RA was evaluated by edema and the withdrawal threshold of hind paws. The maxillae were removed, and alveolar bone loss (ABL) and bone radiographic density (BRD) were evaluated. Immunohistochemical analyses for interleukins (IL)-6 and -17 and nuclear factor (NF)-κB were performed. Our results showed that EA reduced only the pain intensity in arthritic rats. Histomorphometric, macroscopic, and radiographic analyses did not show differences between the control and EP/EA groups. EA caused a reduction in ABL and BRD only in the presence of EP. EA caused a reduction in IL-6 and -17 in all groups, but NF-κB was only reduced in the arthritic rats with EP. In conclusion, EA reduced the inflammation related to periodontitis in arthritic rats but did not prevent ABL.

Carotid sinus nerve stimulation attenuates alveolar bone loss and inflammation in experimental periodontitis.

Baroreceptor and chemoreceptor reflexes modulate inflammatory responses. However, whether these reflexes attenuate periodontal diseases has been poorly examined. Thus, the present study determined the effects of electrical activation of the carotid sinus nerve (CSN) in rats with periodontitis. We hypothesized that activation of the baro and chemoreflexes attenuates alveolar bone loss and the associated inflammatory processes. Electrodes were implanted around the CSN, and bilateral ligation of the first mandibular molar was performed to, respectively, stimulate the CNS and induce periodontitis. The CSN was stimulated daily for 10 min, during nine days, in unanesthetized animals. On the eighth day, a catheter was inserted into the left femoral artery and, in the next day, the arterial pressure was recorded. Effectiveness of the CNS electrical stimulation was confirmed by hypotensive responses, which was followed by the collection of a blood sample, gingival tissue, and jaw. Long-term (9 days) electrical stimulation of the CSN attenuated bone loss and the histological damage around the first molar. In addition, the CSN stimulation also reduced the gingival and plasma pro-inflammatory cytokines induced by periodontitis. Thus, CSN stimulation has a protective effect on the development of periodontal disease mitigating alveolar bone loss and inflammatory processes.

Hyperoside ameliorates periodontitis in rats by promoting osteogenic differentiation of BMSCs via activation of the NF-κB pathway.

Hyperoside, as an active compound, widely exists in a large number of Chinese herbal medicines and has been reported to possess anti-inflammatory and diuretic properties. However, the effects and underlying mechanisms of hyperoside on periodontitis have not been previously reported. In this study, we found that hyperoside ameliorates symptoms of periodontitis in a rat model, with improvements in alveolar bone resorption, relief of inflammatory infiltration, increase in orderly arrangement of collagen fibers and increase of osteogenic differentiation. In addition, hyperoside promoted proliferation, up-regulated EdU-positive cells, decreased cell-cycle distribution and increased the protein expression of Ki67 and PCNA in rat bone mesenchymal stem cells (rBMSCs), as revealed by Cell Counting Kit-8, EdU, flow cytometry and western blot analysis. Moreover, hyperoside significantly promoted osteogenic differentiation, as shown by quantitative RT-PCR, western blot and alizarin red staining assays. Furthermore, hyperoside activated the nuclear factor-κB (NF-κB) signaling pathway in rBMSCs, similar to the results observed in vivo. Finally, BMS345541, an inhibitor of the NF-κB signaling pathway, could reverse the effects of hyperoside on the biological functions in rBMSCs. In conclusion, our results suggest that hyperoside has potential therapeutic properties against periodontitis via promotion of proliferation and osteogenic differentiation of rBMSCs via activation of the NF-κB signaling pathway.