Associations of Antibodies Targeting Periodontal Pathogens With Subclinical Coronary, Carotid, and Peripheral Arterial Atherosclerosis in Rheumatoid Arthritis.

OBJECTIVE: Both periodontal disease and cardiovascular disease (CVD) are overrepresented in rheumatoid arthritis (RA). This study was undertaken to investigate the contribution of periodontal pathogens to CVD in RA. METHODS: RA patients underwent assessments of coronary artery calcification (CAC), carotid intima-media thickness and plaque, and ankle-brachial index via computed tomography, ultrasound, and Doppler ultrasound, respectively. Sera were assayed for antibodies targeting Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans serotype B (Aa), and Aa-derived leukotoxin A (LtxA). Associations of antibodies against these periodontal pathogens with measures of atherosclerosis were explored using generalized linear models. RESULTS: Among 197 RA patients, anti-Pg was detected in 72 patients (37%), anti-Aa in 41 patients (21%), and anti-LtxA in 84 patients (43%). Adjusting for relevant confounders and reported tooth loss, the mean CAC score was 90% higher in those with anti-Aa and/or anti-LtxA compared with those without either antibody (19 units versus 10 units; P = 0.033). The adjusted odds of CAC ≥100 units were 2.23-fold higher in those with anti-Aa and/or anti-LtxA compared with those without either antibody (P = 0.040). Anti-Aa and/or anti-LtxA seropositivity was significantly associated with all other assessed measures of atherosclerosis except carotid plaque. Anti-Pg was not associated with any measure of atherosclerosis. Higher swollen joint count was associated with CAC exclusively in the group with anti-Aa and/or anti-LtxA. CONCLUSION: Immunoreactivity against Aa and/or its major virulence factor LtxA was associated with atherosclerosis in multiple vascular beds of RA patients and amplified the effect of swollen joints on coronary atherosclerosis, suggesting a role for treatment/prevention of periodontal disease in the prevention of CVD in RA.

O-Polysaccharide Plays a Major Role on the Virulence and Immunostimulatory Potential of Aggregatibacter actinomycetemcomitans During Periodontal Infection.

Aggregatibacter actinomycetemcomitans is a Gram-negative oral bacterium with high immunostimulatory and pathogenic potential involved in the onset and progression of periodontitis, a chronic disease characterized by aberrant immune responses followed by tooth-supporting bone resorption, which eventually leads to tooth loss. While several studies have provided evidence related to the virulence factors of A. actinomycetemcomitans involved in the host cell death and immune evasion, such as its most studied primate-specific virulence factor, leukotoxin, the role of specific lipopolysaccharide (LPS) domains remain poorly understood. Here, we analyzed the role of the immunodominant domain of the LPS of A. actinomycetemcomitans termed O-polysaccharide (O-PS), which differentiates the distinct bacterial serotypes based on its antigenicity. To determine the role of the O-PS in the immunogenicity and virulence of A. actinomycetemcomitans during periodontitis, we analyzed the in vivo and in vitro effect of an O-PS-defective transposon mutant serotype b strain, characterized by the deletion of the rmlC gene encoding the α-L-rhamnose sugar biosynthetic enzyme. Induction of experimental periodontitis using the O-PS-defective rmlC mutant strain resulted in lower tooth-supporting bone resorption, infiltration of Th1, Th17, and Th22 lymphocytes, and expression of Ahr, Il1b, Il17, Il23, Tlr4, and RANKL (Tnfsf11) in the periodontal lesions as compared with the wild-type A. actinomycetemcomitans strain. In addition, the O-PS-defective rmlC mutant strain led to impaired activation of antigen-presenting cells, with less expression of the co-stimulatory molecules CD40 and CD80 in B lymphocytes and dendritic cells, and downregulated expression of Tnfa and Il1b in splenocytes. In conclusion, these data demonstrate that the O-PS from the serotype b of A. actinomycetemcomitans plays a key role in the capacity of the bacterium to prime oral innate and adaptive immune responses, by triggering the Th1 and Th17-driven tooth-supporting bone resorption during periodontitis.

Weissella cibaria CMU exerts an anti­inflammatory effect by inhibiting Aggregatibacter actinomycetemcomitans­induced NF­κB activation in macrophages.

Periodontitis is a chronic inflammatory disease caused by various periodontal pathogens. Weissella cibaria CMU (oraCMU) is a probiotic that promotes oral health. However, its anti­inflammatory effects against periodontal pathogens have not yet been investigated. The present study evaluated the anti­inflammatory effects of live oraCMU against stimulation with the formalin­inactivated periodontal pathogen Aggregatibacter actinomycetemcomitans in RAW 264.7 macrophages. Cell viability was analyzed by the MTS assay in a dose­dependent manner (at multiplicities of infection of 0.1, 1, 10, 100 and 1,000). Nitric oxide (NO) was monitored using the Griess test. The mRNA expression of proinflammatory cytokines such as interleukin (IL)1ß and IL6 was assessed by reverse transcription­quantitative PCR. Western blotting was used to examine the effects of oraCMU on the phosphorylation of NF­κB inhibitor α (IκBα) and IκBα kinase (IKK), the nuclear translocation of the NF­κB subunit p65 and the expression of inducible NO synthase (iNOS). Live oraCMU had no cytotoxic effects on RAW 264.7 macrophages. In A. actinomycetemcomitans­stimulated RAW 264.7 macrophages, oraCMU reduced NO production by suppressing iNOS expression and downregulating the mRNA expression of proinflammatory cytokines in a dose­dependent manner. IKK phosphorylation and IκBα degradation were dose­dependently inhibited by oraCMU and the nuclear translocation of p65 via the canonical NF­κB pathway was simultaneously reduced. The results indicated that oraCMU possessed anti­inflammatory activity associated with the inhibition of NF­κB signal activation in response to periodontal pathogens. This suggests that oraCMU is a beneficial anti­inflammatory probiotic that can aid in the maintenance of oral health.

Humoral immune response to heat shock protein 60 of Aggregatibacter actinomycetemcomitans and cross-reactivity with malondialdehyde acetaldehyde-modified LDL.

Atherosclerosis is a chronic inflammatory disease and major cause of mortality worldwide. One of the crucial steps for atherosclerotic plaque development is oxidation of low-density lipoprotein (LDL). Through the oxidation, highly immunogenic epitopes are created and the immune system is activated. Association between atherosclerosis and periodontal diseases is well documented, and one of the main oral pathogens common in periodontitis is Aggregatibacter actinomycetemcomitans (Aa). Heat shock protein 60 (HSP60) is an important virulence factor for Aa bacteria and a strong activator of the immune system. Cross-reactivity of HSP60 and oxidized LDL (OxLDL) antibodies could be a potential mechanism in the progression of atherosclerosis and one possible link between atherosclerosis and periodontitis. Human plasma samples from neonates and mothers were analyzed to determine if antibody titer to Aa-HSP60 protein is already present in newborns. Further objectives were to characterize antibody response in Aa-HSP60 immunized mice and to determine possible antibody cross-reaction with oxidized LDL. We demonstrated that newborns already have IgM antibody levels to Aa-HSP60. We also showed that in mice, Aa-HSP60 immunization provoked IgG and IgM antibody response not only to Aa-HSP60 but also to malondialdehyde acetaldehyde-modified LDL (MAA-LDL). Competition assay revealed that the antibodies were specific to Aa-HSP60 and cross-reacted with MAA-LDL. Our results suggest a possibility of molecular mimicry between Aa-HSP60 and MAA-LDL, making it intriguing to speculate on the role of HSP60 protein in atherosclerosis that manifests at young age.

Association of rheumatoid arthritis disease activity and antibodies to periodontal bacteria with serum lipoprotein profile in drug naive patients.

Objective: We investigated lipid concentrations, particle sizes and antibodies binding to periodontal bacteria Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis and to malondialdehyde-acetaldehyde (MAA) modified low-density lipoprotein in immunoglobulin (Ig) class A, G and M among patients with newly diagnosed rheumatoid arthritis (RA) in a population-based cohort.Methods: Concentrations and sizes of lipoprotein particles analysed by proton nuclear magnetic resonance spectroscopy and antibody levels to MAA modified low-density lipoprotein were studied at baseline and after one-year of follow-up. Serum Ig A and G class antibodies to periodontal bacteria were determined at baseline.Results: Sixty-three patients were divided into tertiles according to disease activity by disease activity score with 28 joint count and erythrocyte sedimentation rate (ESR) (<3.9, 3.9-4.7, >4.7). Small low-density lipoprotein concentration was lowest in the tertile with the highest disease activity. In high-density lipoprotein, the concentrations of total, medium and small particles decreased with disease activity. The particle size in low-density lipoprotein associated with disease activity and the presence of antibodies to P. gingivalis. Ig G and M antibodies to MAA modified low-density lipoprotein correlated with disease activity. Inflammation associated changes faded by one year.Conclusions: Drug naive RA patients had proatherogenic changes in lipid profiles, but they were reversible, when inflammation diminished.Key messagesPatients with drug naive rheumatoid arthritis showed proatherogenic lipid profiles.Reversible changes in lipid profiles can be achieved as response to inflammation suppression.Active therapy aimed at remission is essential in all patients with rheumatoid arthritis.

Aggregatibacter actinomycetemcomitans (Aa) Under the Radar: Myths and Misunderstandings of Aa and Its Role in Aggressive Periodontitis.

Aggregatibacter actinomycetemcomitans (Aa) is a low-abundance Gram-negative oral pathobiont that is highly associated with a silent but aggressive orphan disease that results in periodontitis and tooth loss in adolescents of African heritage. For the most part Aa conducts its business by utilizing strategies allowing it to conceal itself below the radar of the host mucosal immune defense system. A great deal of misinformation has been conveyed with respect to Aa biology in health and disease. The purpose of this review is to present misconceptions about Aa and the strategies that it uses to colonize, survive, and evade the host. In the process Aa manages to undermine host mucosal defenses and contribute to disease initiation. This review will present clinical observational, molecular, and interventional studies that illustrate genetic, phenotypic, and biogeographical tactics that have been recently clarified and demonstrate how Aa survives and suppresses host mucosal defenses to take part in disease pathogenesis. At one point in time Aa was considered to be the causative agent of Localized Aggressive Periodontitis. Currently, it is most accurate to look at Aa as a community activist and necessary partner of a pathogenic consortium that suppresses the initial host response so as to encourage overgrowth of its partners. The data for Aa's activist role stems from molecular genetic studies complemented by experimental animal investigations that demonstrate how Aa establishes a habitat (housing), nutritional sustenance in that habitat (food), and biogeographical mobilization and/or relocation from its initial habitat (transportation). In this manner Aa can transfer to a protected but vulnerable domain (pocket or sulcus) where its community activism is most useful. Aa's "strategy" includes obtaining housing, food, and transportation at no cost to its partners challenging the economic theory that "there ain't no such thing as a free lunch." This "strategy" illustrates how co-evolution can promote Aa's survival, on one hand, and overgrowth of community members, on the other, which can result in local host dysbiosis and susceptibility to infection.

Sphingosine-1-Phosphate Receptor 2 Controls Podosome Components Induced by RANKL Affecting Osteoclastogenesis and Bone Resorption.

Proinflammatory cytokine production, cell chemotaxis, and osteoclastogenesis can lead to inflammatory bone loss. Previously, we showed that sphingosine-1-phosphate receptor 2 (S1PR2), a G protein coupled receptor, regulates inflammatory cytokine production and osteoclastogenesis. However, the signaling pathways regulated by S1PR2 in modulating inflammatory bone loss have not been elucidated. Herein, we demonstrated that inhibition of S1PR2 by a specific S1PR2 antagonist (JTE013) suppressed phosphoinositide 3-kinase (PI3K), mitogen-activated protein kinases (MAPKs), and nuclear factor kappa-B (NF-κB) induced by an oral bacterial pathogen, Aggregatibacter actinomycetemcomitans, and inhibited the release of IL-1ß, IL-6, TNF-α, and S1P in murine bone marrow cells. In addition, shRNA knockdown of S1PR2 or treatment by JTE013 suppressed cell chemotaxis induced by bacteria-stimulated cell culture media. Furthermore, JTE013 suppressed osteoclastogenesis and bone resorption induced by RANKL in murine bone marrow cultures. ShRNA knockdown of S1PR2 or inhibition of S1PR2 by JTE013 suppressed podosome components, including PI3K, Src, Pyk2, integrin ß3, filamentous actin (F-actin), and paxillin levels induced by RANKL in murine bone marrow cells. We conclude that S1PR2 plays an essential role in modulating proinflammatory cytokine production, cell chemotaxis, osteoclastogenesis, and bone resorption. Inhibition of S1PR2 signaling could be a novel therapeutic strategy for bone loss associated with skeletal diseases.

Effect of periodontal treatment on Aggregatibacter actinomycetemcomitans colonization and serum IgG levels against A. actinomycetemcomitans serotypes and Omp29 of aggressive periodontitis patients.

OBJECTIVE: To evaluate the effect of the periodontal treatment on Aggregatibacter actinomycetemcomitans JP2 clone, and the IgG serum levels against its outer membrane protein (Omp29) and A. actinomycetemcomitans serotypes in aggressive periodontitis (AgP). SUBJECTS AND METHODS: Seventeen patients with generalized (GAgP), 10 with localized (LAgP), and 10 healthy controls were included. AgP participants were submitted to periodontal treatment-scaling and root planing plus antibiotics (SRP+A). Periodontal parameters, for example, probing depth (PD) and clinical attachment loss (CAL), were evaluated at baseline and at 1-year. Serum IgG against Omp29 and serotypes a, b, and c were determined by ELISA. The levels of A. actinomycetemcomitans JP2 clone were determined in subgingival biofilm samples by qPCR. RESULTS: Periodontal treatment resulted in significant reductions of PD, CAL, and IgG levels against Omp29, serotypes b, and c. After therapy, IgG levels against A. actinomycetemcomitans serotypes, as well as the levels of the JP2 clone in AgP, became similar to controls. The reduction in JP2 clone count was correlated with a reduction of PD and IgG response against Omp29. CONCLUSION: Scaling and root planing plus antibiotics decreased IgG levels response against Omp29 and A. actinomycetemcomitans serotypes involved in the disease (b and c), while the serum response increased against tne commensal serotype (a), similar to what occurs in periodontally healthy individuals.

Functionality of the Interleukin 8 haplotypes in lymphocytes and macrophages in response to gram-negative periodontopathogens.

Individuals carrying the ATC/TTC haplotype (Hap-1) in the interleukin 8 (IL8) gene were reported as more susceptible to chronic periodontitis (CP), an infectious disease associated with Gram-negative bacteria, in comparison to patients with the ATT/TTC haplotype (Hap-2). This study investigated the functionality of the IL8 haplotypes in lymphocytes and monocytes of individuals carrying the Hap-1 or Hap-2 IL8 haplotypes in the response to CP-associated Gram-negative bacteria (periodontopathogens). Peripheral blood was collected from 6 subjects carrying each haplotype, and their immune cells were challenged with periodontopathogens or phorbol 12-myristate 13-acetate (PMA) plus Ionomycin. Depending on the immune cell type (lymphocytes or monocyte-derived macrophages) the assessed outcomes were: phenotypical polarization, gene expression, phagocytic activity, chemotaxis and production of reactive oxygen species (ROS). Subjects carrying the Hap-1 haplotype showed increased expression of IL8 and TNFA and significantly skewing towards pro-inflammatory Th1/M1/Th17 phenotypes. There was increased percentage of ROS-producing monocyte-derived macrophages from individuals carrying the Hap-1 haplotype. Cells from individuals presenting the Hap-2 haplotype had an overall attenuated response to periodontopathogens, with a significant shift towards the Treg phenotype. In conclusion, the IL8 haplotypes showed to be functional both in monocyte-derived macrophages and lymphocytes. The Hap-1 haplotype previously associated with increased susceptibility to CP demonstrated greater skewing to pro-inflammatory Th1/M1/Th17 phenotypes and production of ROS.

Aggregatibacter actinomycetemcomitans leukotoxin causes activation of lymphocyte function-associated antigen 1.

Repeats-in-toxin leukotoxin (LtxA) produced by the oral bacterium Aggregatibacter actinomycetemcomitans kills human leukocytes in a lymphocyte function-associated antigen 1 (LFA-1, integrin αL /ß2 )-dependent manner, although the mechanism for this interaction has not been identified. The LtxA internalisation by LFA-1-expressing cells was explored with florescence resonance energy transfer (FRET) microscopy using a cell line that expresses LFA-1 with a cyan fluorescent protein-tagged cytosolic αL domain and a yellow fluorescent protein-tagged ß2 domain. Phorbol 12-myristate 13-acetate activation of LFA-1 caused transient cytosolic domain separation. However, addition of LtxA resulted in an increase in FRET, indicating that LtxA brings the cytosolic domains closer together, compared with the inactive state. Unlike activation, this effect was not transient, lasting more than 30 min. Equilibrium constants of LtxA binding to the cytoplasmic domains of both αL and ß2 were determined using surface plasmon resonance. LtxA has a strong affinity for the cytosolic domains of both the αL and ß2 subunits (Kd  = 15 and 4.2 nM, respectively) and a significantly lower affinity for the cytoplasmic domains of other integrin αM , αX , and ß3 subunits (Kd  = 400, 180, and 230 nM, respectively), used as controls. Peptide fragments of αL and ß2 show that LtxA binds membrane-proximal domain of αL and intermediate domain of ß2 .

Rheumatoid Arthritis-Associated Autoimmunity Due to Aggregatibacter actinomycetemcomitans and Its Resolution With Antibiotic Therapy.

Background:Aggregatibacter actinomycetemcomitans (Aa) is a Gram-negative coccobacillus recognized as a pathogen in periodontitis and infective endocarditis. By producing a toxin (leukotoxin A, LtxA) that triggers global hypercitrullination in neutrophils, Aa has been recently linked to rheumatoid arthritis (RA) pathogenesis. Although mechanistic and clinical association studies implicate Aa infection in the initiation of autoimmunity in RA, direct evidence in humans is lacking. Case:We describe a 59-year-old man with anti-citrullinated protein antibody (ACPA)-positive RA who presented for evaluation of refractory disease. He was found to have Aa endocarditis. Following antibiotic treatment, joint symptoms resolved and ACPAs normalized. Given the implications for RA immunopathogenesis, we further investigated the bacterial, genetic and immune factors that may have contributed to the patient's clinical and autoimmune phenotypes. Methods:DNA was extracted from serum and used to amplify the Aa leukotoxin (ltx) promoter region by PCR, which was further analyzed by Sanger sequencing. High-resolution identification of HLA alleles was performed by sequenced based typing (SBT). TNF-α, IFN-γ, GM-CSF, IL-1ß, IL-6, IL-8, IL-17A, IL-18, IL-21, and IL-22 were quantified in serum by a multiplex immunoassay. IgG and IgA antibodies to Aa LtxA were assayed by ELISA. Results:Aa genotyping confirmed infection with a highly leukotoxic strain carrying a 530-bp ltx promoter deletion, shown to result in 10- to 20-fold higher bacterial expression of LtxA. Immuno-phenotyping showed high anti-LtxA antibodies, elevated cytokines implicated in RA pathogenesis (Th1/Th17), and specific host susceptibility conferred by three HLA alleles strongly linked to ACPAs and RA (DRB1*04:04, DRB1*15:01, and DPB1*04:01). One year after eradication of Aa, the patient remained free of arthritis and anti-CCP antibodies. Conclusion: In the context of genetic risk for RA, systemic subacute infection with a leukotoxic strain of Aa can drive ACPA production and a clinical phenotype similar to RA.

Detection of antibodies against Aggregatibacter actinomycetemcomitans in serum and saliva through ELISA in periodontally healthy individuals and individuals with chronic periodontitis.

BACKGROUND: Periodontitis is a persistent polymicrobial infection, which leads to chronic inflammation in the tooth supporting tissues. Aggregatibacter actinomycetemcomitans are normal commensals of oral cavity but are low in number in periodontally healthy subjects. They are one of the major pathogens aetiologically linked to periodontal disease. Plasma and salivary antibody measurement may be useful to support diagnosis, disease activity, classification and prognosis of periodontitis. The aim of the present study was to investigate the association between the serum and salivary antibody levels to A. actinomycetemcomitans and therefore, to find whether this association was varying in different grades of periodontitis. METHOD: Total of 50 periodontally healthy and 50 chronic periodontitis subjects (35-65 years) of both sexes were included for the study. 2 ml of un-stimulated saliva and 5 ml of venous blood was collected under sterile conditions. The detection of antibodies against A. actinomycetemcomitans in periodontally healthy individuals and individuals with chronic periodontitis was performed using indirect ELISA. RESULTS: Results showed serum IgG, IgA mean levels against A. actinomycetemcomitans were higher in chronic periodontitis subjects compared to mean levels in periodontally healthy subjects. Similarly, salivary IgG, IgA levels were also raised in chronic periodontitis patients as compared in healthy subjects. Also the mean levels of serum IgG and salivary IgA were increased as the severity of disease increased. CONCLUSION: Antibody titer using saliva and serum could be useful tool for screening of patients with chronic periodontitis. Further, monitoring the various phases of treatment outcome using saliva could be a useful, non-invasive, prognostic indicator.

Phosphorylcholine is located in Aggregatibacter actinomycetemcomitans fimbrial protein Flp 1.

Phosphorylcholine (ChoP) is covalently incorporated into bacterial surface structures, contributing to host mimicry and promoting adhesion to surfaces. Our aims were to determine the frequency of ChoP display among Aggregatibacter actinomycetemcomitans strains, to clarify which surface structures bear ChoP, and whether ChoP-positivity relates to serum killing. The tested oral (N = 67) and blood isolates (N = 27) represented 6 serotypes. Mab TEPC-15 was used for immunoblotting of cell lysates and fractions and for immunofluorescence microscopy of cell surface-bound ChoP. The lysates were denatured with urea for hidden ChoP or treated with proteinase K to test whether it binds to a protein. Three ChoP-positive and two ChoP-negative strains were subjected to serum killing in the presence/absence of CRP and using Ig-depleted serum as complement source. Cell lysates and the first soluble cellular fraction revealed a < 10 kDa band in immunoblots. Among 94 strains, 27 were ChoP positive. No difference was found in the prevalence of ChoP-positive oral (21/67) and blood (6/27) strains. Immunofluorescence microscopy corresponded to the immunoblot results. Proteinase K abolished ChoP reactivity, whereas urea did not change the negative result. The TEPC-15-reactive protein was undetectable in Δflp1 mutant strain. The survival rate of serotype-b strains in serum was 100% irrespective of ChoP, but that of serotype-a was higher in ChoP-positive (85%) than ChoP-negative (71%) strains. The results suggest that a third of rough-colony strains harbor ChoP and that ChoP is attached to fimbrial subunit protein Flp1. It further seems that ChoP-positivity does not enhance but may reduce A. actinomycetemcomitans susceptibility to serum killing.

Serotype a of Aggregatibacter actinomycetemcomitans down-regulates the increased serotype b-induced cytokine and chemokine production in dendritic cells.

OBJECTIVE: In Aggregatibacter actinomycetemcomitans, different serotypes have been described based on LPS antigenicity. Mixed infection with the different A. actinomycetemcomitans serotypes is frequent in periodontitis patients; accordingly, the role of this bacterial species in the pathogenesis of periodontitis may differ depending whether patients or periodontal lesions harbour one or more of the A. actinomycetemcomitans serotypes. We hypothesized that different combinations of these serotypes could be associated with distinct host responses and hence different inflammatory patterns. This investigation was aimed to assess whether the increased immuno-stimulatory potential attributed to the serotype b of A. actinomycetemcomitans on immune cells is able to be modified during co-infection with other A. actinomycetemcomitans serotypes. METHODS: Dendritic cells (DCs) were obtained from healthy subjects and stimulated with the different A. actinomycetemcomitans serotypes or their purified LPS using the following stimulatory conditions: serotype a, b, or c, and the combinations a+b, a+c, b+c, or a+b+c. The cytokine, CCR, and CCL levels were quantified by qPCR and ELISA. RESULTS: Higher levels of cytokines, CCRs, and CCLs were induced when DCs were stimulated with the serotype b of A. actinomycetemcomitans compared with the same cells stimulated with the other serotypes. When DCs were co-infected, these levels decreased in comparison with the serotype b-stimulation alone, in particular when the serotype a was present in the mixed infection. CONCLUSIONS: The increased immuno-stimulatory potential attributed to the serotype b was modified when DCs were co-infected with other A. actinomycetemcomitans serotypes, in particular, when the serotype a was present, the DC response diminished.

Dual action of highbush blueberry proanthocyanidins on Aggregatibacter actinomycetemcomitans and the host inflammatory response.

BACKGROUND: The highbush blueberry (Vaccinium corymbosum) has a beneficial effect on several aspects of human health. The present study investigated the effects of highbush blueberry proanthocyanidins (PACs) on the virulence properties of Aggregatibacter actinomycetemcomitans and macrophage-associated inflammatory responses. METHODS: PACs were isolated from frozen highbush blueberries using solid-phase chromatography. A microplate dilution assay was performed to determine the effect of highbush blueberry PACs on A. actinomycetemcomitans growth as well as biofilm formation stained with crystal violet. Tight junction integrity of oral keratinocytes was assessed by measuring the transepithelial electrical resistance (TER), while macrophage viability was determined with a colorimetric MTT assay. Pro-inflammatory cytokine and MMP secretion by A. actinomycetemcomitans-stimulated macrophages was quantified by ELISA. The U937-3xκB-LUC monocyte cell line transfected with a luciferase reporter gene was used to monitor NF-κB activation. RESULTS: Highbush blueberry PACs reduced the growth of A. actinomycetemcomitans and prevented biofilm formation at sub-inhibitory concentrations. The treatment of pre-formed biofilms with the PACs resulted in a loss of bacterial viability. The antibacterial activity of the PACs appeared to involve damage to the bacterial cell membrane. The PACs protected the oral keratinocytes barrier integrity from damage caused by A. actinomycetemcomitans. The PACs also protected macrophages from the deleterious effect of leukotoxin Ltx-A and dose-dependently inhibited the secretion of pro-inflammatory cytokines (IL-1ß, IL-6, CXCL8, TNF-α), matrix metalloproteinases (MMP-3, MMP-9), and sTREM-1 by A. actinomycetemcomitans-treated macrophages. The PACs also inhibited the activation of the NF-κB signaling pathway. CONCLUSION: The antibacterial and anti-inflammatory properties of highbush blueberry PACs as well as their ability to protect the oral keratinocyte barrier and neutralize leukotoxin activity suggest that they may be promising candidates as novel therapeutic agents.

MyD88-mediated innate sensing by oral epithelial cells controls periodontal inflammation.

Periodontal diseases are a class of non-resolving inflammatory diseases, initiated by a pathogenic subgingival biofilm, in a susceptible host, which if left untreated can result in soft and hard tissue destruction. Oral epithelial cells are the first line of defense against microbial infection within the oral cavity, whereby they can sense the environment through innate immune receptors including toll-like receptors (TLRs). Therefore, oral epithelial cells directly and indirectly contribute to mucosal homeostasis and inflammation, and disruption of this homeostasis or over-activation of innate immunity can result in initiation and/or exacerbation of localized inflammation as observed in periodontal diseases. Dynamics of TLR signaling outcomes are attributable to several factors including the cell type on which it engaged. Indeed, our previously published data indicates that oral epithelial cells respond in a unique manner when compared to canonical immune cells stimulated in a similar fashion. Thus, the objective of this study was to evaluate the role of oral epithelial cell innate sensing on periodontal disease, using a murine poly-microbial model in an epithelial cell specific knockout of the key TLR-signaling molecule MyD88 (B6K5Cre.MyD88plox). Following knockdown of MyD88 in the oral epithelium, mice were infected with Porphorymonas gingivalis and Aggregatibacter actinomycetemcomitans by oral lavage 4 times per week, every other week for 6 weeks. Loss of oral epithelial cell MyD88 expression resulted in exacerbated bone loss, soft tissue morphological changes, soft tissue infiltration, and soft tissue inflammation following polymicrobial oral infection. Most interestingly while less robust, loss of oral epithelial cell MyD88 also resulted in mild but statistically significant soft tissue inflammation and bone loss even in the absence of a polymicrobial infection. Together these data demonstrate that oral epithelial cell MyD88-dependent TLR signaling regulates the immunological balance within the oral cavity under conditions of health and disease.

Association between specific periodontal pathogens, Toll-like receptor-4, and nuclear factor-κB expression in placental tissues of pre-eclamptic women with periodontitis.

AIM: The aim of the present study was to determine the association between the presence of specific periodontal pathogens, Toll-like receptor-4 (TLR-4), and nuclear factor-κB (NF-κB) expression in the placental tissues of pre-eclamptic women. METHODS: Antenatal periodontal screening was performed in 25 normotensive pregnant women and 25 pre-eclamptic women. Subgingival plaque and placental tissue samples were collected from both groups and screened for the presence of Porphyromonas gingivalis (P. gingivalis), Tannerella forsythia, Aggregatibacter actinomycetemcomitans, and Prevotella intermedia (P. intermedia) using real-time polymerase chain reaction. The placental samples were also analyzed to quantify TLR-4 and NF-κB expression. RESULTS: The subgingival plaque samples of pre-eclamptic women showed significantly higher frequencies of P. intermedia. In the placental samples, P. gingivalis, P. intermedia, and the expression of TLR-4 and NF-κB were found to be at significantly higher levels compared to normotensive pregnant women. Using linear regression analysis, the expression of TLR-4 was significantly influenced by the presence of P. gingivalis (coefficient=3.176, 95% confidence interval [CI]: 367-5.986) and P. intermedia (coefficient=2.886, 95% CI: 0.77-5.696), whereas NF-κB expression was influenced only by the presence of P. intermedia (coefficient=2.220, 95% CI: 0.051-4.388) in the placental tissues of pre-eclamptic women. CONCLUSION: An association exists between P. gingivalis and P. intermedia with increased TLR-4 and NF-κB expression in the placenta of pre-eclamptic women with periodontitis.

Periodontal pathogenic bacteria, Aggregatibacter actinomycetemcomitans affect non-alcoholic fatty liver disease by altering gut microbiota and glucose metabolism.

Increasing evidence indicates that periodontitis affects non-alcoholic fatty liver disease (NAFLD). We examined the relationship between periodontal bacterial infection and clinical/biochemical parameters in 52 NAFLD patients. Anti-Aggregatibacter actinomycetemcomitans (Aa) antibody titers correlated positively with visceral fat, fasting plasma insulin, and HOMA-IR; and negatively with the liver/spleen ratio. C57BL/6J mice (8-weeks-old) were given Aa or saline (control) for 6 weeks, and were fed either normal chow (NCAa, NCco) or high-fat diet (HFAa and HFco). NCAa and HFAa mice presented impaired glucose tolerance and insulin resistance compared to control mice. HFAa mice showed higher hepatic steatosis than HFco animals. Liver microarray analysis revealed that 266 genes were differentially expressed between NCAa and NCco mice. Upregulated genes in Aa-administrated mice were enriched for glucagon signaling pathway, adipocytokine signaling pathway and insulin resistance. Consistently, plasma glucagon concentration was higher in NCAa mice. In addition, Akt phosphorylation was lower in the liver of NCAa/HFAa than in NCco/HFco mice. Based on 16S rRNA sequencing, Aa administration changed composition of the gut microbiota. Metagenome prediction in gut microbiota showed upregulation of fatty acid biosynthesis and downregulation of fatty acid degradation in Aa-administered mice. Thus, infection with Aa affects NAFLD by altering the gut microbiota and glucose metabolism.

Pro-inflammatory cytokine responses in human gingival epithelial cells after stimulation with cell wall extract of Aggregatibacter actinomycetemcomitans subtypes.

Varying cytokine responses of human gingival epithelial cells (HGECs) by Aggregatibacter actinomycetemcomitans subtypes have been found. Most studies have used reference strains, whereas a few has evaluated the cytokine expression in response to clinical subtypes of this bacterial species. This study aimed to examine whether there was any difference in cytokine responses of HGECs stimulated with cell wall extract (CWE) from A. actinomycetemcomitans subtypes included clinical strains from Thai adult periodontitis, various serotypes and non-serotypeable strains, strains from deep or shallow pockets, and reference serotype strains. Totally 50 clinical strains and 7 reference strains of A. actinomycetemcomitans were analyzed for the expression of IL-1ß, IL-6, IL-8, and TNF-α mRNAs in HGECs by real time-PCR, and the IL-8 concentrations in cell-free supernatant measured using ELISA. An in vitro effect of released IL-8 on neutrophil migration was examined using transwell chambers. Result showed that among four cytokines studied, IL-8 mRNA was highly up-regulated by both clinical and reference strains. Serotype f revealed the highest expression compared to other serotypes. The JP2-like leukotoxin promoter gene and non-serotypeable (NS1 and NS2) demonstrated lower IL-8 responses compared to serotypeable strains, and IL-8 responses upon stimulation with clinical strains from deep pockets were also significantly lower than those isolated from shallow pockets (P < 0.01). Our findings suggest that the clinical isolates of A. actinomycetemcomitans associating with deep pockets, JP2-like leukotoxin promoter gene, NS1, and NS2 may interfere neutrophil function via minimal and immunosuppressing IL-8 responses, which may enhance their survival and virulence.

Natural Monoclonal Antibody to Oxidized Low-Density Lipoprotein and Aggregatibacter actinomycetemcomitans.

Natural antibodies are produced by B lymphocytes without exogenous antigenic exposure and are present at the time of birth. They usually bind to conserved epitopes on antigens of different chemical compositions. We cloned and characterized a natural mouse monoclonal IgM antibody (Aa_Mab) by selecting the binding to malondialdehyde acetaldehyde (MAA) adducts on low-density lipoprotein (LDL). The data showed that the Aa_Mab cross-reacted with Aggregatibacter actinomycetemcomitans (Aa) bacteria, an important oral pathogen in periodontitis associated with atherosclerosis. Surprisingly, the binding molecule of Aa bacteria to the Aa_Mab was Aa chaperonin 60 or HSP60, a protein that is not only responsible for maintaining cellular proteins conformation, but also functions as a potent virulence factor prompting bone resorption in periodontitis and as a putative pathogenic factor in atherosclerosis.