Periodontitis and hypertension are linked through systemic inflammation: A 5-year longitudinal study.

AIM: To investigate the associations between periodontitis and hypertension and potential mediation via systemic inflammation through a 5-year longitudinal study. MATERIALS AND METHODS: The severity and extent of periodontitis were determined using probing depth (PD). Oral hygiene was assessed using plaque scores. The associations between periodontal variables and 5-year blood pressure changes or incident hypertension were analysed using linear or Poisson regression, adjusting for potential confounders. Mediation analysis of two systemic inflammatory biomarkers, namely white blood cell count (WBC) and C-reactive protein (CRP) levels, was performed. RESULTS: The study population included 901 hypertension-free participants, aged 50-73 years. Greater mean PD, higher percentage of sites with PD ≥ 6 mm and poor oral hygiene were associated with elevated systolic blood pressure and increased hypertension risk (relative risks = 1.17 [95% confidence interval [CI]: 1.02-1.34], 1.13 [95% CI: 1.02-1.26] and 1.08 [95% CI: 1.03-1.13], respectively). Periodontitis and poor oral hygiene were associated with higher WBC and CRP levels (p < .05), which, in turn, were associated with increased hypertension risk (p < .05). WBC and CRP jointly mediated 14.1%-26.9% of the associations between periodontal variables and incident hypertension. CONCLUSIONS: Periodontitis and poor oral hygiene were associated with increased hypertension risk, and systemic inflammation was, in part, a mediator of these associations.

Human dental pulp stem cell responses to different dental pulp capping materials.

BACKGROUND: Direct pulp capping is a vital pulp therapy for a pin-point dental pulp exposure. Applying a pulp capping material leads to the formation of a dentin bridge and protects pulp vitality. The aim of this study was to compare the effects of four dental materials, DyCal®, ProRoot® MTA, Biodentine™, and TheraCal™ LC in vitro. METHODS: Human dental pulp stem cells (hDPs) were isolated and characterized. Extraction medium was prepared from the different pulp capping materials. The hDP cytotoxicity, proliferation, and migration were examined. The odonto/osteogenic differentiation was determined by alkaline phosphatase, Von Kossa, and alizarin red s staining. Osteogenic marker gene expression was evaluated using real-time polymerase chain reaction. RESULTS: ProRoot® MTA and Biodentine™ generated less cytotoxicity than DyCal® and TheraCal™ LC, which were highly toxic. The hDPs proliferated when cultured with the ProRoot® MTA and Biodentine™ extraction media. The ProRoot® MTA and Biodentine™ extraction medium induced greater cell attachment and spreading. Moreover, the hDPs cultured in the ProRoot® MTA or Biodentine™ extraction medium migrated in a similar manner to those in serum-free medium, while a marked reduction in cell migration was observed in the cells cultured in DyCal® and TheraCal™ LC extraction media. Improved mineralization was detected in hDPs maintained in ProRoot® MTA or Biodentine™ extraction medium compared with those in serum-free medium. CONCLUSION: This study demonstrates the favorable in vitro biocompatibility and bioactive properties of ProRoot® MTA and Biodentine™ on hDPs, suggesting their superior regenerative potential compared with DyCal® and TheraCal™.

Periodontitis is associated with elevated serum levels of cardiac biomarkers-Soluble ST2 and C-reactive protein.

AIM: This cross-sectional study examined the associations between periodontitis and the serum cardiac biomarkers-soluble ST2 (sST2) and C-reactive protein (CRP)-in systemically healthy adults. MATERIALS AND METHODS: Periodontitis severity was determined using mean probing depth (PD) or clinical attachment level (CAL) and a categorical variable (no/mild, moderate, or severe). Oral hygiene was evaluated using plaque scores. Regression analyses assessed the associations between periodontal variables and sST2 or CRP levels, adjusting for age, sex, smoking, body mass index, systolic blood pressure, fasting plasma glucose, and high-density or low-density lipoprotein cholesterol. RESULTS: The study population comprised 799 individuals, aged 50-73 years. After multivariable adjustment, greater mean PD/CAL, severe periodontitis, and poor oral hygiene were associated with elevated sST2 and CRP levels (p < 0.05). Greater mean PD or CAL was associated with increased odds of having sST2 in the top quintile (>22.7 µg/L) (odds ratio [OR] [95% confidence interval (CI)]: 1.7 [1.1-2.4] and 1.3 [1.1-1.7], respectively) and CRP > 3 mg/L (OR: 1.5 [1.1-2.1] and 1.3 [1.0-1.5], respectively). Individuals with poor oral hygiene were more likely to have sST2 > 22.7 µg/L (OR: 2.0 [1.0-4.0]) and CRP > 3 mg/L (OR: 2.0 [1.1-3.5]), compared to those with good oral hygiene. CONCLUSIONS: Periodontitis and poor oral hygiene were associated with elevated serum sST2 and CRP levels.

Gene expression profiling of Jagged1-treated human periodontal ligament cells.

OBJECTIVE: Jagged1 regulates several biological functions in human periodontal ligament cells (hPDLs). The present study aimed to evaluate mRNA expression profiling of Jagged1-treated hPDLs using microarray technique. METHODS: Notch ligands, Jagged1, were indirectly immobilized on tissue culture surface. Subsequently, hPDLs were seeded on Jagged1 immobilized surface and maintained in growth medium for 48 hr. Total RNA was collected and processed. Gene expression profiling was examined using microarray technique. Real-time polymerase chain reaction and immunofluorescence staining were employed to determine mRNA and protein expression levels, respectively. Cell proliferation and colony-forming unit assay were performed. Cell cycle was evaluated using propidium iodide staining and flow cytometry analysis. RESULTS: The isolated cells demonstrated fibroblast-like morphology and exhibited the co-expression of CD44, CD90, and CD105 surface markers. After stimulated with Jagged1, the total of 411 genes was differentially expressed, consisting both coding and non-coding genes. For coding genes, 165 and 160 coding genes were upregulated and downregulated, respectively. Pathway analysis revealed that the upregulated genes were mainly involved in cellular interactions, signal transduction, and collagen formation and degradation while the downregulated genes were in the events and phases in cell cycle. Jagged1 significantly decreased cell proliferation, reduced colony-forming unit ability, and induced G0/G1 cell cycle arrest in hPDLs. CONCLUSION: Jagged1 regulates various biological pathways in hPDLs. This gene expression profiling could help to understand the mechanisms potentially involved in the Notch signaling regulation in periodontal homeostasis.

Human Memory B Cells in Healthy Gingiva, Gingivitis, and Periodontitis.

The presence of inflammatory infiltrates with B cells, specifically plasma cells, is the hallmark of periodontitis lesions. The composition of these infiltrates in various stages of homeostasis and disease development is not well documented. Human tissue biopsies from sites with gingival health (n = 29), gingivitis (n = 8), and periodontitis (n = 21) as well as gingival tissue after treated periodontitis (n = 6) were obtained and analyzed for their composition of B cell subsets. Ag specificity, Ig secretion, and expression of receptor activator of NF-κB ligand and granzyme B were performed. Although most of the B cell subsets in healthy gingiva and gingivitis tissues were CD19(+)CD27(+)CD38(-) memory B cells, the major B cell component in periodontitis was CD19(+)CD27(+)CD38(+)CD138(+)HLA-DR(low) plasma cells, not plasmablasts. Plasma cell aggregates were observed at the base of the periodontal pocket and scattered throughout the gingiva, especially apically toward the advancing front of the lesion. High expression of CXCL12, a proliferation-inducing ligand, B cell-activating factor, IL-10, IL-6, and IL-21 molecules involved in local B cell responses was detected in both gingivitis and periodontitis tissues. Periodontitis tissue plasma cells mainly secreted IgG specific to periodontal pathogens and also expressed receptor activator of NF-κB ligand, a bone resorption cytokine. Memory B cells resided in the connective tissue subjacent to the junctional epithelium in healthy gingiva. This suggested a role of memory B cells in maintaining periodontal homeostasis.

The activation of B cells enhances DC-SIGN expression and promotes susceptibility of B cells to HPAI H5N1 infection.

The interplay between highly pathogenic avian influenza (HPAI) H5N1 virus and immune cells has been extensively studied for years, as host immune components are thought to play significant roles in promoting the systemic spread of the virus and responsible for cytokine storm. Previous studies suggested that the interaction of B cells and monocytes could promote HPAI H5N1 infection by enhancing avian influenza virus receptor expression. In this study, we further investigate the relationship between the HPAI H5N1 virus, activated B cells, and DC-SIGN expression. DC-SIGN has been described as an important factor for mediating various types of viral infection. Here, we first demonstrate that HPAI H5N1 infection could induce an activation of B cells, which was associated with DC-SIGN expression. Using CD40L and recombinant IL-4 for B cell stimulation, we determined that DC-SIGN expressed on activated B cells was able to enhance its susceptibility to HPAI H5N1 infection. Our findings uncover the interplay between this H5N1 virus and B cells and provide important information in understanding how the virus overcomes our immune system, contributing to its unusual immunopathogenesis.

Tissue Distribution of Memory T and B Cells in Rhesus Monkeys following Influenza A Infection.

Studies of influenza-specific immune responses in humans have largely assessed systemic responses involving serum Ab and peripheral blood T cell responses. However, recent evidence indicates that tissue-resident memory T (TRM) cells play an important role in local murine intrapulmonary immunity. Rhesus monkeys were pulmonary exposed to 2009 pandemic H1N1 virus at days 0 and 28 and immune responses in different tissue compartments were measured. All animals were asymptomatic postinfection. Although only minimal memory immune responses were detected in peripheral blood, a high frequency of influenza nucleoprotein-specific memory T cells was detected in the lung at the "contraction phase," 49-58 d after second virus inoculation. A substantial proportion of lung nucleoprotein-specific memory CD8(+) T cells expressed CD103 and CD69, phenotypic markers of TRM cells. Lung CD103(+) and CD103(-) memory CD8(+) T cells expressed similar levels of IFN-γ and IL-2. Unlike memory T cells, spontaneous Ab secreting cells and memory B cells specific to influenza hemagglutinin were primarily observed in the mediastinal lymph nodes. Little difference in systemic and local immune responses against influenza was observed between young adult (6-8 y) and old animals (18-28 y). Using a nonhuman primate model, we revealed substantial induction of local T and B cell responses following 2009 pandemic H1N1 infection. Our study identified a subset of influenza-specific lung memory T cells characterized as TRM cells in rhesus monkeys. The rhesus monkey model may be useful to explore the role of TRM cells in local tissue protective immunity after rechallenge and vaccination.

The presence of monocytes enhances the susceptibility of B cells to highly pathogenic avian influenza (HPAI) H5N1 virus possibly through the increased expression of α2,3 SA receptor.

The highly pathogenic avian influenza (HPAI) H5N1 virus causes severe systemic infection in avian and mammalian species, including humans by first targeting immune cells. This subsequently renders the innate and adaptive immune responses less active, thus allowing dissemination of the virus to systemic organs. To gain insight into the pathogenesis of H5N1, this study aims to determine the susceptibility of human PBMCs to the H5N1 virus and explore the factors which influence this susceptibility. We found that PBMCs were a target of H5N1 infection, and that monocytes and B cells were populations which were clearly the most susceptible. Analysis of PBMC subpopulations showed that isolated monocytes and monocytes residing in whole PBMCs had comparable percentages of infection (28.97 ± 5.54% vs 22.23 ± 5.14%). In contrast, isolated B cells were infected to a much lower degree than B cells residing in a mixture of whole PBMCs (0.88 ± 0.34% vs 34.87 ± 4.63%). Different susceptibility levels of B cells for these tested conditions spurred us to explore the B cell-H5N1 interaction mechanisms. Here, we first demonstrated that monocytes play a crucial role in the enhancement of B cell susceptibility to H5N1 infection. Although the actual mechanism by which this enhancement occurs remains in question, α2,3-linked sialic acid (SA), known for influenza virus receptors, could be a responsible factor for the greater susceptibility of B cells, as it was highly expressed on the surface of B cells upon H5N1 infection of B cell/monocyte co-cultures. Our findings reveal some of the factors involved with the permissiveness of human immune cells to H5N1 virus and provide a better understanding of the tropism of H5N1 in immune cells.

Alveolar Bone Loss in a Ligature-Induced Periodontitis Model in Rat Using Different Ligature Sizes.

OBJECTIVES: Ligature-induced periodontitis model has been widely used as a preclinical stage for investigating new treatment modalities. However, the effect of different ligature sizes on alveolar bone loss has never been studied. Therefore, we examined alveolar bone loss in this rat model using different sizes of silk ligatures, as well as healing after ligature removal. MATERIALS AND METHODS: Left maxillary second molars of Sprague-Dawley rats were ligated with 3-0, 4-0, or 5-0 silk ligatures (n = 4-5/group) for 14 days before harvested maxillae and gingival tissues. For subsequent experiment, animals were ligated for 14 days using the ligature size that induced the most alveolar bone loss before ligature removal and sacrificed at 0, 7 and 14 days (n = 5-6/group). All maxillae and gingival tissues were harvested to evaluate alveolar bone level, tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) levels. STATISTICAL ANALYSIS: Data was analyzed using SPSS Statistics 23.0 software (SPSS Inc., Chicago, Illinois, United States). Data from all experiments were tested for normality using Shapiro-Wilk test. Data between ligatured and nonligatured teeth were compared using Student's t-test or Wilcoxon signed-rank test. Differences among different ligature sizes were analyzed by analysis of variance followed by multiple comparisons with post-hoc test. A p-value less than 0.05 was considered statistically significant. RESULTS: The alveolar bone loss of ligated teeth was substantially higher than that of control after 14 days of ligation. While 3-0 and 4-0 resulted in significantly greater bone loss than 5-0 silk, the 3-0 group had the lowest rate of ligature loss. Therefore, alveolar bone healing postligature removal was investigated further using 3-0 silk. The results showed no significant bone level change at 2 weeks after ligature removal. In term of IL-1ß and TNF-α levels, there was no statistically significant difference in IL-1ß level between groups at any time point, while TNF-α was undetectable. CONCLUSION: These data showed that 3-0 silk was the most effective ligature size in promoting alveolar bone loss comparing with 4-0 and 5-0 silk. During the 2-week period following ligature removal, spontaneous bone healing was not observed.

MxA expression induced by α-defensin in healthy human periodontal tissue.

Although periodontal tissue is continually challenged by microbial plaque, it is generally maintained in a healthy state. To understand the basis for this, we investigated innate antiviral immunity in human periodontal tissue. The expression of mRNA encoding different antiviral proteins, myxovirus resistance A (MxA), protein kinase R (PKR), oligoadenylate synthetase (OAS), and secretory leukocyte protease inhibitor (SLPI) were detected in both healthy tissue and that with periodontitis. Immunostaining data consistently showed higher MxA protein expression in the epithelial layer of healthy gingiva as compared with tissue with periodontitis. Human MxA is thought to be induced by type I and III interferons (IFNs) but neither cytokine type was detected in healthy periodontal tissues. Treatment in vitro of primary human gingival epithelial cells (HGECs) with α-defensins, but not with the antimicrobial peptides ß-defensins or LL-37, led to MxA protein expression. α-defensin was also detected in healthy periodontal tissue. In addition, MxA in α-defensin-treated HGECs was associated with protection against avian influenza H5N1 infection and silencing of the MxA gene using MxA-targeted-siRNA abolished this antiviral activity. To our knowledge, this is the first study to uncover a novel pathway of human MxA induction, which is initiated by an endogenous antimicrobial peptide, namely α-defensin. This pathway may play an important role in the first line of antiviral defense in periodontal tissue.

Effects of lipopolysaccharide on proliferation, migration and osteogenic differentiation of apical papilla cells from early and late stage of root development.

The aim of this study was to investigate the effects of lipopolysaccharide on cell proliferation, migration and osteogenic differentiation of apical papilla cells from early and late stage of root development. After challenging with various lipopolysaccharide concentrations to apical papilla cells from both stages of root development for 168 h, cell proliferation and migration were investigated. Osteogenic differentiation was examined by Alizarin red staining, and gene expressions of bone/cementum or dentin-related genes were examined by polymerase chain reaction. Lipopolysaccharide did not affect cell proliferation and migration in both groups. Lipopolysaccharide at 1 and 5 µg mL-1 increased Alizarin red staining in apical papilla cells from early-stage but not the late-stage cells. Bone sialoprotein (bone/cementum marker) gene expression increased in both early and late stage of root development at 5 µg mL-1 . These results might explain bone/cementum generation in regenerative endodontic procedures.

Antiviral immune responses in H5N1-infected human lung tissue and possible mechanisms underlying the hyperproduction of interferon-inducible protein IP-10.

Information on the immune response against H5N1 within the lung is lacking. Here we describe the sustained antiviral immune responses, as indicated by the expression of MxA protein and IFN-alpha mRNA, in autopsy lung tissue from an H5N1-infected patient. H5N1 infection of primary bronchial/tracheal epithelial cells and lung microvascular endothelial cells induced IP-10, and also up-regulated the retinoic acid-inducible gene-I (RIG-I). Down-regulation of RIG-I gene expression decreased IP-10 response. Co-culturing of H5N1-infected pulmonary cells with TNF-alpha led to synergistically enhanced production of IP-10. In the absence of viral infection, TNF-alpha and IFN-alpha also synergistically enhanced IP-10 response. Methylprednisolone showed only a partial inhibitory effect on this chemokine response. Our findings strongly suggest that both the H5N1 virus and the locally produced antiviral cytokines; IFN-alpha and TNF-alpha may have an important role in inducing IP-10 hyperresponse, leading to inflammatory damage in infected lung.

Indoleamine 2,3-dioxygenase expression and regulation in chronic periodontitis.

BACKGROUND: Indoleamine 2,3-dioxygenase (IDO) is an intracellular tryptophan-oxidizing enzyme with immunosuppressive characteristics. Its expression and regulation in periodontal tissues are unknown. The aim of this study was to determine IDO expression in healthy gingiva and chronic periodontitis lesions. In addition, the effect of inflammatory cytokines and bacterial products on the expression and activity of DOI in human gingival fibroblasts (HGFs) was assessed. METHODS: Human gingival tissue samples were obtained from patients who underwent periodontal surgery. IDO expression in healthy gingiva and periodontitis lesions was determined by immunohistochemistry. HGF cells were treated with interferon-gamma (IFN-gamma), interleukin (IL)-1beta, tumor necrosis factor-alpha (TNF-alpha), and lipopolysaccharides from Porphyromonas gingivalis (PgLPS). IDO mRNA expression was determined by reverse transcription-polymerase chain reaction. The IDO enzymatic activity was determined by measuring the kynurenine level using a colorimetric method. RESULTS: In gingival tissues, IDO expression was detected in epithelial cells, fibroblasts, endothelial cells, and inflammatory mononuclear cells. IDO expression was higher in periodontitis lesions than in healthy gingiva. HGFs did not constitutively express IDO. IFN-gamma strongly induced IDO expression and activity in HGFs, in a dose-dependent manner. IL-1beta, TNF-alpha, and PgLPS were also able to induce IDO expression in HGF cells. IFN-gamma in combination with IL-1beta, TNF-alpha, or PgLPS showed enhanced IDO expression. CONCLUSIONS: IDO was expressed in human gingiva, and the expression was upregulated in chronic periodontitis. The increased IDO expression in periodontitis lesions may be due, in part, to the activation of HGFs by inflammatory cytokines and bacterial products.

Jagged1 promotes mineralization in human bone-derived cells.

OBJECTIVES: The present study aimed to investigate the expression of Notch signaling components during osteogenic differentiation in vitro and bone healing in vivo. In addition, the influence of Notch signaling on osteogenic differentiation of human bone-derived cells was examined. METHODS: Gene expression profiling of osteogenic differentiation of human bone marrow-derived mesenchymal stromal cells in vitro (GSE80614) and bone healing period of murine tibial fracture in vivo (GSE99388) was downloaded from Gene Expression Omnibus database. The expression of Notch signaling components was obtained from bioinformatic tools. Human bone-derived cells were isolated from alveolar and iliac bone. Cells were seeded on Jagged1 immobilized surface. Osteogenic marker gene expression and mineralization were examined using real-time polymerase chain reaction and alizarin red s staining, respectively. RESULTS: From bioinformatic analysis of gene expression profiling, various Notch signaling components were differentially expressed during osteogenic differentiation of human bone marrow-derived mesenchymal stromal cells in vitro and bone healing period of murine tibial fracture in vivo. The common genes differentially regulated of these two datasets were Hes1, Aph1a, Nsctn, Furin, Adam17, Hey1, Pcsk5, Nedd4, Jag1, Heyl, Notch3, Dlk1, and Hey2. For an in vitro analysis, the mineral deposition markedly increased after seeding human bone-derived cells on Jagged1 immobilized surface, correspondingly with the increase of ALP mRNA expression. Jagged1 treatment downregulated TWIST2 mRNA expression in both human alveolar and iliac bone-derived cells. CONCLUSION: Notch signaling is regulated during osteogenic differentiation and bone healing. In addition, the activation of Notch signaling promotes osteogenic differentiation in human alveolar and iliac bone-derived cells. Therefore, Notch signaling manipulation could be a useful approach for enhancing bone regeneration.

Memory T cell subsets in healthy gingiva and periodontitis tissues.

BACKGROUND: In the gingival sulcus, effective and balanced innate and adaptive immune responses against subgingival plaque microbiome are crucial to maintain immune homeostasis. In this study, we investigated the memory T cell subsets in healthy gingiva and periodontitis tissues. METHODS: Anatomical localization of T cells (CD3+ , CD4+ , and CD8+ ) in healthy gingiva and periodontitis tissues were examined immunohistochemically. Subsets of memory T cells from isolated gingival cells were analyzed by flow cytometry using a cocktail of monoclonal antibodies (anti-CD69, anti-CD103, anti-CD45RA, anti-CCR7, anti-CD28, and anti-CD95). Intracellular cytokine staining of interleukin (IL)-17 and interferon (IFN)-γ expression on memory T cells in periodontitis tissues was also investigated. RESULTS: We found that healthy gingiva contains two memory T cell populations; a CD69- recirculating population and a CD69+ gingiva-resident memory T cell population. CD4+ T cells with transitional memory (TTM ) phenotype (CD45RA- CCR7- CD28+ CD95+ ) constitute the major subset within these two populations. A significant increase in the proportion of CD4+ CD69+ CD103- memory T cells was observed in periodontitis tissues compared with healthy gingiva. CD4+ memory T cells from periodontitis tissues produced either IL-17 or IFN-γ whereas CD8+ memory T cells produced only IFN-γ. CONCLUSIONS: Our findings suggest that recirculating and gingiva-resident memory T cells could represent an important part of the immune surveillance network in the connective tissue, maintaining periodontal homeostasis. Imbalance of subgingival bacterial communities could damage gingival barrier allowing bacterial antigens to get access to the deeper connective tissue where they activate memory T cells leading to deleterious inflammation; a hallmark of periodontitis.

Cell wall mannan of Candida krusei mediates dendritic cell apoptosis and orchestrates Th17 polarization via TLR-2/MyD88-dependent pathway.

Dendritic cells (DCs) abundantly express diverse receptors to recognize mannans in the outer surface of Candida cell wall, and these interactions dictate the host immune responses that determine disease outcomes. C. krusei prevalence in candidiasis worldwide has increased since this pathogen has developed multidrug resistance. However, little is known how the immune system responds to C. krusei. Particularly, the molecular mechanisms of the interplay between C. krusei mannan and DCs remain to be elucidated. We investigated how C. krusei mannan affected DC responses in comparison to C. albicans, C. tropicalis and C. glabrata mannan. Our results showed that only C. krusei mannan induced massive cytokine responses in DCs, and led to apoptosis. Although C. krusei mannan-activated DCs underwent apoptosis, they were still capable of initiating Th17 response. C. krusei mannan-mediated DC apoptosis was obligated to the TLR2 and MyD88 pathway. These pathways also controlled Th1/Th17 switching possibly by virtue of the production of the polarizing cytokines IL-12 and IL-6 by the C. krusei mannan activated-DCs. Our study suggests that TLR2 and MyD88 pathway in DCs are dominant for C. krusei mannan recognition, which differs from the previous reports showing a crucial role of C-type lectin receptors in Candida mannan sensing.

The effects of Porphyromonas gingivalis LPS and Actinobacillus actinomycetemcomitans LPS on human dendritic cells in vitro, and in a mouse model in vivo.

Interaction between different bacterial plaque pathogens and dendritic cells may induce different types of T helper (Th) cell response, which is critical in the pathogenesis of periodontitis. In this study we investigated the effects of lipopolysaccharide (LPS) from Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans on human monocyte-derived dendritic cells (Mo-DCs) with respect to co-stimulatory molecule expression, cytokine production and Th cell differentiation. Unlike Escherichia coli and A. actinomycetemcomitans LPS, P. gingivalis LPS induced only low levels of CD40, CD80, HLA-DR and CD83 expression on Mo-DCs. LPS from both bacteria induced considerably lower TNF-alpha and IL-10 than did E. coli LPS. LPS from all three bacteria induced only negligible IL-12 production. In a human mixed-leukocyte reaction, and in an ovalbumin-specific T cell response assay in mice, both types of LPS suppressed IFN-gamma production. In conclusion, stimulation by P. gingivalis LPS and A. actinomycetemcomitans LPS appears to bias Mo-DCs towards Th2 production.