Pg Lipopolysaccharide Research Articles

Atopic biomarker changes after exposure to Porphyromonas gingivalis lipopolysaccharide: a small experimental study in Wistar rats

Background IgE and IgG4 are implicated in atopic development and clinically utilized as major biomarkers. Atopic responses following certain pathogens, such as Porphyromonas gingivalis (Pg), are currently an area of interest for further research. The aim of this study is to measure the level of IgE, IgG4, and IgG4/IgE ratio periodically after exposure of periodontal pathogen Pg lipopolysaccharide (LPS). Methods We used 16 Wistar rats (Rattus norvegicus) randomly subdivided into four groups: Group 1, injected with placebo; Group 2, injected with 0.3 µg/mL of Pg LPS; Group 3, injected with 1 µg/mL of Pg LPS; and Group 4, injected with 3 µg/mL of Pg LPS. Sera from all groups were taken from retro-orbital plexus before and after exposure. Results Levels of IgE and IgG4 increased significantly following exposure of Pg LPS at day-4 and day-11. Greater increase of IgE rather than IgG4 contributed to rapid decline of IgG4/IgE ratio, detected in the peripheral blood at day-4 and day-11. Conclusion Modulation of atopic responses following exposure to Pg is reflected by a decrease in IgG4/IgE ratio that accompanies an increase of IgE. Therefore, Pg, a keystone pathogen during periodontal disease, may have a tendency to disrupt atopic biomarkers.

Increased Resolvin E1 Production by Peripheral Blood Mononuclear Cells in Periodontitis Patients: Pilot Study.

This study quantified the production of the pro-resolving agent Resolvin E1 by peripheral blood mononuclear cells (PBMC) from 20 systemically healthy volunteers with and without periodontitis after stimulation with lipopolysaccharide (LPS) from Porphyromonas gingivalis (Pg). Ten periodontitis patients and 10 healthy volunteers (30-50 years old), matched by age and sex, were recruited. Peripheral blood mononuclear cells were isolated and stimulated in culture plates for 24 hours with Pg LPS. Resolvin E1 levels were measured in the supernatants by enzyme-linked immunosorbent assay. Significantly higher production of Resolvin E1 was observed in both groups when stimulated with LPS compared to baseline levels (p<0.001). A significant increase in Resolvin E1 was observed in the presence of Lipopolysaccharide in the patients with periodontitis compared to the healthy group (p=0.0019). Resolvin E1 levels may reflect a measure of resolution of inflammation that warrants further clinical investigation.

Effects of metformin on human gingival fibroblasts: an in vitro study

ObjectiveTo investigate the effects of metformin (MF) treatment on the matrix metalloproteinases (MMPs) and proinflammatory cytokines production from lipopolysaccharide (LPS) - stimulated human gingival fibroblasts (HGFs).MethodsHGFs were obtained from subcultures of biopsies from clinically healthy gingival tissues of patients undergoing oral surgeries. Cell cytotoxicity assay was used to determine the effect of different concentrations of MF on viability of HGFs. HGFs were then incubated and treated with different concentrations of MF and Porphyromonas gingivais (Pg) LPS. MMP-1, MMP-2, MMP-8, MMP-9, IL-1β, and IL-8 expression analysis was performed using xMAP technology (Luminex 200, Luminex, Austin, TX, USA). Student’s t-test for a single sample was used to compare the mean values of the study groups with the control value. A p-value of <0.05 and 95% confidence intervals were used to report the statistical significance and precision of mean values.ResultsConcentrations of 0.5, 1- and 2-mM MF had a minimal non-significant cytotoxic effect on the HGFs and caused statistically significant reduction of MMP-1, MMP-2, MMP-8 and IL-8 expressed by the LPS-stimulated HGFs.ConclusionThe results of the present study confirm that MF suppresses MMP-1, MMP-2, MMP-8 and IL-8 in LPS-stimulated HGFs suggesting an anti-inflammatory effect of MF and potential adjunct therapeutic role in the treatment of periodontal diseases.

Extracellular vesicles derived from Porphyromonas gingivalis induce trigeminal nerve-mediated cognitive impairment

IntroductionPorphyromonas gingivalis (PG)-infected periodontitis is in close connection with the development of Alzheimer’s disease (AD). PG-derived extracellular vesicles (pEVs) contain inflammation-inducing virulence factors, including gingipains (GPs) and lipopolysaccharide (LPS). ObjectivesTo understand how PG could cause cognitive decline, we investigated the effects of PG and pEVs on the etiology of periodontitis and cognitive impairment in mice. MethodsCognitive behaviors were measured in the Y-maze and novel object recognition tasks. Biomarkers were measured using ELISA, qPCR, immunofluorescence assay, and pyrosequencing. ResultspEVs contained neurotoxic GPs and inflammation-inducible fimbria protein and LPS. Gingivally exposed, but not orally gavaged, PG or pEVs caused periodontitis and induced memory impairment-like behaviors. Gingival exposure to PG or pEVs increased TNF-α expression in the periodontal and hippocampus tissues. They also increased hippocampal GP+Iba1+, LPS+Iba1+, and NF-κB+Iba1+ cell numbers. Gingivally exposed PG or pEVs decreased BDNF, claudin-5, and N-methyl-D-aspartate receptor expression and BDNF+NeuN+ cell number. Gingivally exposed fluorescein-5-isothiocyanate-labeled pEVs (F-pEVs) were detected in the trigeminal ganglia and hippocampus. However, right trigeminal neurectomy inhibited the translocation of gingivally injected F-EVs into the right trigeminal ganglia. Gingivally exposed PG or pEVs increased blood LPS and TNF-α levels. Furthermore, they caused colitis and gut dysbiosis. ConclusionGingivally infected PG, particularly pEVs, may cause cognitive decline with periodontitis. PG products pEVs and LPS may be translocated into the brain through the trigeminal nerve and periodontal blood pathways, respectively, resulting in the cognitive decline, which may cause colitis and gut dysbiosis. Therefore, pEVs may be a remarkable risk factor for dementia.

Downregulation of miRNA-26 in chronic periodontitis interferes with innate immune responses and cell migration by targeting phospholipase C beta 1.

To evaluate the potential role of miR-26 family members in periodontal pathogenesis by assessing innate immune responses to periopathic bacteria and regulation of cytoskeletal organization. Expression of miR-26a-5p and miR-26b-5p was quantified in gingival biopsies derived from healthy and periodontally diseased subjects before and after non-surgical (scaling and root planing) therapy by RT-qPCR. Global pathway analysis and luciferase assays were performed for target identification and validation. Cytokine expression was assessed in miR-26a-5p transfected human oral keratinocytes upon stimulation with either live Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans or Pg lipopolysaccharide (LPS). Wound closure assays were performed in cells transfected with miR-26a-5p, while the impact on cytoskeletal organization was assessed by F-actin staining. miR-26a-5p and miR-26b-5p were downregulated in diseased gingiva and restored 4-6 weeks post-therapy to levels comparable with healthy subjects. Target validation assays identified phospholipase C beta 1 as a bona fide novel target exhibiting antagonistic expression pattern in disease and post-therapy cohorts. miR-26a-5p transfected cells secreted higher levels of cytokine/chemokines upon stimulation with periopathogens and demonstrated impaired cell migration and cytoskeletal rearrangement. Downregulated miR-26a-5p levels in periodontal inflammation may interfere with key cellular functions that may have significant implications for host defence and wound healing.

(Invited) Salivary Lipopolysaccharide (LPS) Detection Using Lateral Flow Sandwich-Based Immunoassay Point-of-Care Devices

Endotoxins, also known as lipopolysaccharides (LPS), are important macromolecules existing in the outmost part of Gram-negative bacteria, which are generated when the bacteria are in growing and stationary phases. Large numbers of LPS molecules are released when the bacteria die. For example, a single E. coli bacterium can release ~ 2 million LPS molecules. Once LPS is released, the lipid A part is exposed to the host’s immune system, eliciting strong immune response, including various inflammations, potentially life-threatening sepsis, and septic shock. Gingivitis is a sign of disturbance in the oral microbiome by overgrowing Gram-negative bacteria. More than 50% of global population has some level of gingivitis, which can worsen to periodontitis if it is not properly treated. Periodontitis is a severe gum infection disease that eventually leads to tooth loss and other serious health complications. [1]While endotoxins induce a strong immune response in hosts, they can also serve as important biomarkers to diagnose various bacterial diseases. P. gingivalis, one of > 500 bacteria species found in subgingival plaque is a major Gram-negative pathogenic bacterium that is responsible for chronic periodontitis. LPS from P. gingivalis (PG LPS) induces significant host responses in gingival tissue by increasing the production of inflammatory biomarkers. Furthermore, because of the close relationship between P. gingivalis and other important systemic diseases, such as cardiovascular diseases and neurodegenerative (Alzheimer’s) disease that has emerged in recent years, quantitative evaluation of PG LPS has become a key measure in oral health, as well as in the whole body health system.[2]Considering the increasing significance of P. gingivalis LPS, high demand for a novel point-of-care device has emerged for both early diagnosis and frequent monitoring of PG LPS levels. Traditional qualitative detection of bacterial biomarkers is carried out mostly utilizing the well-known PCR method, which requires trained personnel and a relatively longer time span in a laboratory setting. Lateral flow assay is one of the most promising POC platforms with many benefits, such as low cost, simple fabrication process, user-friendly colorimetric interface, rapid turnaround time, and no need for external instruments.[3]We have developed a point-of-care lateral flow assay (LFA) device to detect and quantify PG LPS concentrations in human saliva using the sandwich assay approach with two different antibodies. Fig. 1a shows the basic concept of our sandwich immunoassay on the LFA device. LPS is a large biomacromolecule with multiple binding sites, which is very beneficial for utilizing the more sensitive sandwich-type approach versus competitive immunoassay approach. Two different antibodies are utilized in the device. A monoclonal antibody (mAb) is conjugated to the surface of gold nanoparticles (AuNP) to capture PG LPS molecules in the sample solution. A polyclonal antibody (pAb) is printed and immobilized on the nitrocellulose membrane of LFA device in order to form a test line for capturing the AuNP conjugates bound to PG LPS from the sample solution. When LPS is present in the sample solution, the mAb-conjugated AuNP particles (mAb-AuNP) bind to LPS. Then the combined LPS-mAb-AuNP conjugate particles flow through the porous nitrocellulose membrane and are captured by the immobilized pAb in the test line stripe on the LFA. Polyclonal antibodies can bind to other available binding sites on the LPS membrane that were not utilized by the monoclonal antibody. When sufficient LPS-mAb-AuNP particles are captured a reddish test line is observed on the nitrocellulose membrane. The control line on the LFA is printed on the LFA using protein G, which captures the monoclonal antibody on the AuNP’s in order to validate the test by confirming the conjugation status between mAb and AuNP. Fig. 1b shows the test line intensity at multiple LPS concentrations. The test line intensity increases linearly with LPS concentration, with the effective linear dynamic range up to ~2 µg/mL concentration and a limit of detection of ~ 22 ng/mL. Also, while the assay presented the strongest test line intensity for P. gingivalis, neither a-mucin, which is most abundant protein in saliva, nor E. coli LPS produced a test line signal. P. pallens LPS, which is related to Gingivitis disease, resulted in a much weaker test line formation. Park, B.S. and J.-O. Lee, Recognition of lipopolysaccharide pattern by TLR4 complexes. Experimental & Molecular Medicine, 2013. 45(12): p. e66-e66.He, W., et al., Point-of-Care Periodontitis Testing: Biomarkers, Current Technologies, and Perspectives. Trends in Biotechnology, 2018. 36(11): p. 1127-1144.Dalirirad, S., D. Han, and A.J. Steckl, Aptamer-Based Lateral Flow Biosensor for Rapid Detection of Salivary Cortisol. ACS Omega, 2020, 51: p. 32890–32898.doi.org/10.1021/acsomega.0c03223 Figure 1

Topical application of Porphyromonas gingivalis into thegingival pocket in mice leads to chronic‑activeinfection, periodontitis and systemic inflammation.

Porphyromonas gingivalis (Pg), one of the 'red-complex' perio-pathogens known to play a critical role in the development of periodontitis, has been used in various animal models to mimic human bacteria-induced periodontitis. In order to achieve a more realistic animal model of human Pg infection, the present study investigated whether repeated small-volume topical applications of Pg directly into the gingival pocket can induce local infection, including periodontitis and systemic vascular inflammation in wild-type mice. Freshly cultured Pg was topically applied directly into the gingival pocket of the second molars for 5 weeks (3 times/week). After the final application, the mice were left in cages for 4 or 8 weeks and sacrificed. The status of Pg colony formation in the pocket, gingival inflammation, alveolar bone loss, the expression levels of pro-inflammatory cytokines in the serum and aorta, the presence of anti-Pg lipopolysaccharide (LPS) and gingipain (Kpg and RgpB) antibodies in the serum, as well as the accumulation of Pg LPS and gingipain aggregates in the gingiva and arterial wall were evaluated. The topical application of Pg into the gingival pocket induced the following local and systemic pathohistological changes in mice when examined at 4 or 8 weeks after the final topical Pg application: Pg colonization in the majority of gingival pockets; increased gingival pocket depths; gingival inflammation indicated by the increased expression of TNF-α, IL-6 and IL-1β; significant loss of alveolar bone at the sites of topical Pg application; and increased levels of pro-inflammatory cytokines, such as TNF-α, IL-1β, IL-17, IL-13, KC and IFN-γ in the serum in comparison to those from mice receiving PBS. In addition, the Pg application/colonization model induced anti-Pg LPS and gingipain antibodies in serum, as well as the accumulation of Pg LPS and gingipain aggregates in the gingivae and arterial walls. To the best of our knowledge, this mouse model represents the first example of creating a more sustained local infection in the gingival tissues of wild-type mice and may prove to be useful for the investigation of the more natural and complete pathogenesis of the bacteria in the development of local oral and systemic diseases, such as atherosclerosis. It may also be useful for the determination of a treatment/prevention/efficacy model associated with Pg-induced colonization periodontitis in mice.

Molecular hydrogen suppresses Porphyromonas gingivalis lipopolysaccharide-induced increases in interleukin-1 alpha and interleukin-6 secretion in human gingival cells.

Periodontitis is defined as a multifactorial polymicrobial infection accompanied by inflammatory reactions. Porphyromonas gingivalis (Pg) is known as a major pathogen in the initiation and progression of periodontitis, and a major virulence factor is Pg lipopolysaccharide (LPS). Molecular hydrogen (H2) has been reported to act as a gaseous antioxidant, which suppresses periodontitis progression by decreasing gingival oxidative stress. However, no human periodontitis model has examined the anti-inflammatory effects of H2. In this study, we examined the effects of H2 on Pg LPS-induced secretion of 8 types of inflammation markers in a human periodontitis model using human gingival cells with enzyme-linked immunosorbent assays. Our results demonstrated that Pg LPS increased interleukin (IL) 1 alpha (IL-1α) and IL-6 secretion, but H2 significantly suppressed the secretion of both cytokines without cytotoxicity. H2 can suppress the production of IL-1α and IL-6, which are identified as cytokines involved in inflammatory reactions in periodontal disease. Thus, H2 may provide therapeutic applications for periodontitis.

Atopic biomarker changes after exposure to Porphyromonas gingivalis lipopolysaccharide: a small experimental study in Wistar rats

Background: IgE and IgG4 are implicated in atopic development and clinically utilized as major biomarkers. Atopic responses following certain pathogens, such as Porphyromonas gingivalis (Pg), are currently an area of interest for further research. The aim of this study is to measure the level of IgE, IgG4, and IgG4/IgE ratio periodically after exposure of periodontal pathogen Pg lipopolysaccharide (LPS). Methods: We used 16 Wistar rats (Rattus norvegicus) randomly subdivided into four groups: Group 1, injected with placebo; Group 2, injected with LPS Pg 0.3 µg/mL; Group 3, injected with LPS Pg 1 µg/mL; and Group 4, injected with LPS Pg 3 µg/mL. Sera from all groups were taken from retro-orbital plexus before and after exposure. Results: Levels of IgE and IgG4 increased significantly following exposure of LPS Pg at day-4 and day-11. Greater increase of IgE rather than IgG4 contributed to rapid decline of IgG4/IgE ratio, detected in the peripheral blood at day-4 and day-11. Conclusion: Modulation of atopic responses following exposure to LPS Pg is reflected by a decrease in IgG4/IgE ratio that accompanies an increase of IgE. Therefore, Pg, a keystone pathogen during periodontal disease, may have a tendency to disrupt atopic biomarkers.

Implication of Porphyromonas gingivalis in colitis and homeostasis of intestinal epithelium

Emerging evidences have reported that periodontitis can be a risk factor for the pathogenesis of various systemic diseases. Porphyromonas gingivalis (Pg), one of the crucial pathogens in chronic periodontitis, has been spotlighted as a potential cause for the promotion and acceleration of periodontitis-associated systemic disorders. To investigate the association between Pg and intestinal disease or homeostasis, we treated Pg-derived lipopolysaccharide (LPS) in murine colitis model or intestinal organoid, respectively. Pg-derived LPS (Pg LPS) was administrated into chemically induced murine colitis model and disease symptoms were monitored compared with the infusion of LPS derived from E. coli (Ec LPS). Organoids isolated and cultured from mouse small intestine were treated with Pg or Ec LPS and further analyzed for the generation and composition of organoids. In vivo observations demonstrated that both Pg and Ec LPS exerted slight protective effects against murine colitis. Pg LPS did not affect the generation and growth of intestinal epithelial organoids. Among subtypes of epithelial cells, markers for stem cells, goblet cells or Paneth cells were changed in response to Pg LPS. Taken together, these results indicate that Pg LPS leads to partial improvement in colitis and that its treatment does not significantly affect the self-organization of intestinal organoids but may regulate the epithelial composition.

Matrix Metalloproteinase‐9 Release from Porphyromonas gingivalis Lipopolysaccharide (LPS)‐treated Rat Brain Microglia In Vitro

BackgroundThe putative association between periodontal disease (PD), a chronic inflammatory disease and neuroinflammation, a condition which involves brain microglia, remains under investigation. We have reported that Porphyromonas gingivalis (Pg) lipopolysaccharide (LPS), a bacterium implicated in periodontitis, activates both classical (M1‐type) and alternative (M2‐type) activation of neonatal rat microglia (BMG) with concomitant release of superoxide anion, thromboxane B2, cytokines, and chemokines (Faseb Journal 32.1 Supplement: 702.2, 2018). We hypothesized that matrix metalloproteinase 9 (MMP‐9) release by Pg‐treated microglia might be detectable by both ELISA and visualized by confocal fluorescence imaging.MethodsP. gingivalis LPS (Pg LPS) 105 ng/mL from InvivoGen (San Diego, CA) and Escherichia coli LPS (Ec LPS) 026:B6 1 ng/mL from Difco Lab, Detroit, MI (positive control) were used to treat rat BMG for 18 hours at 35.9°C in vitro. MMP‐9 release was assessed with a rat MMP‐9 ELISA kit (R&amp;D Systems). Confocal fluorescence imaging with a Nikon A1R laser confocal microscope was used to identify BMGs using a primary mouse anti‐rat CD11b/c antibody (Ab) (AbD SeroTec, Raleigh, NC), and secondary donkey anti‐mouse Ab (Thermo Fischer, Waltman, MA). MMP‐9 was visualized with a primary rabbit anti‐rat MMP‐9 polyclonal Ab, and secondary goat anti‐rabbit Ab, both from Abcam, Cambridge, MA.ResultsMMP‐9 presence in tissue culture supernates was detectable by ELISA in both Ec LPS and Pg LPS‐treated BMG. In contrast, MMP‐9 was observed by confocal fluorescence imaging only within Ec LPS‐treated BMG but not in Pg LPS‐treated BMG.ConclusionsBoth ELISA and confocal fluorescence imaging provide additional support for our working hypothesis, because Pg LPS stimulated BMGs to release MMP‐9. Thus, our current observations extend our studies on the effect of Pg LPS on rat brain microglia activation and contribute to further characterize the putative role of Pg LPS in both periodontitis, neuroinflammation and neurodegeneration.Support or Funding InformationSupport by College of Dental Medicine, College of Graduate Studies, and Chicago College of Osteopathic Medicine, Midwestern University are gratefully acknowledged.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The Effect of a Lipopolysaccharide from Rhodobacter capsulatus PG on Inflammation Caused by Various Influenza Strains.

The development of a specific inflammation in mice that had been infected by two influenza virus strains, A/chicken/Kurgan/5/2005 (H5N1) and A/Hamburg/2009 MA (H1N1), was studied. We investigated the effect of a non-toxic lipopolysaccharide from Rhodobacter capsulatus PG on the survival and body weight of the mice, production of IgG antibodies, and the induction of pro- and anti-inflammatory cytokines in blood serum. The administration of the R. capsulatus PG lipopolysaccharide was shown to induce interferon-β synthesis, both in healthy and influenza A virus-infected mice, and to promote production of antiviral antibodies in the blood of the influenza-infected animals.

MicroRNA-146a reverses the inhibitory effects of Porphyromonas gingivalis lipopolysaccharide on osteogenesis of human periodontal ligament cells

Objective: To investigate the effects and mechanisms of microRNA-146a (miR-146a) on osteogenic differentiation of human periodontal ligament cells (hPDLC) stimulated by lipopolysaccharide (LPS) of Porphyromonas gingivalis (Pg). Methods: hPDLC were cultured in vitro and induced to the phase of osteogenic differentiation. These cells were divided into five groups: non-osteogenic differentiation cells, osteogenic differentiation cells, osteogenic differentiation cells treated with Pg LPS, osteogenic differentiation cells treated with Pg LPS and miR-146a mimic, osteogenic differentiation cells treated with Pg LPS and miR-146a negative control. Osteogenic markers and mineralization were detected via quantitative real-time PCR (qPCR) and alizarin red staining, respectively. Meanwhile, non-radioactive transcription factor assay was applied to explore the nuclear activity of nuclear factor kappa B (NF-κB) p65 in nuclear extracts of hPDLC. Results: Compared with cells of osteogenic differentiation in non-LPS-stimulated groups, Pg LPS could decrease the markers of osteogenic differentiation of hPDLC such as collagen Ⅰ (Col-Ⅰ), alkaline phosphatase (ALP), Runt-related transcription factor-2 (RUNX2) and osteocalcin (OCN) (P<0.05), inhibit mineralization, and stimulate NF-κB p65 nuclear activity expression (non-LPS stimulated group: 1.023±0.217, LPS stimulated group: 6.252±0.613, P=0.008). However, compared with cells in Pg LPS/miR-146a negative control group, miR-146a increased Col-Ⅰ (P=0.007) and OCN (P=0.049) mRNA expression, rather than ALP (P=0.167) and RUNX2 (P=0.580) at day 3; miR-146a also upregulated mRNA levels of Col-Ⅰ, ALP, RUNX2 and OCN (P<0.05) at day 7 and day 14, and enhance mineralization. Meanwhile, miR-146a mimic could decrease the nuclear activity of NF-κB p65 induced by Pg LPS in hPDLC (miR-146a: 2.427±0.354, negative control: 5.863±0.482, P=0.019). Conclusions: miR-146a could reverse the inhibitory effects of Pg LPS on osteogenic differentiation of hPDLC through enhancing the expression of osteogenic markers and decreasing inflammatory pathway in hPDLC.

P53 mediates lipopolysaccharide-induced inflammation in human gingival fibroblasts.

The role of reactive oxygen species (ROS) in activation of the inflammatory response has been proven in previous study using human gingival fibroblasts (HGFs) to lipopolysaccharide (LPS) from Porphyromonas gingivalis (Pg) stimulation, but its exact mechanism has not been established. ROS can be generated through increased oxidative phosphorylation. P53 originally identified as a tumor suppressor, has been demonstrated to be associated with energy metabolism. We proposed that LPS-induced inflammatory cytokines release in HGFs is mediated by interaction between P53 and ROS levels. HGFs were grown in medium with Pg LPS stimulation. Gene expression was performed by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot analysis. HGFs were also processed by immunofluorescence to characterize the localization of P53. ROS was measured using a multimodal microplate reader and immunofluorescence microscopy. Cellular respiration levels were performed with a high-resolution respirometer. Cytokines secretion was confirmed by enzyme-linked immunosorbent assay. LPS-induced P53 activity and localization in mitochondria led to cellular redox imbalance and mitochondrial dysfunction, thus triggered the cellular inflammatory response with increased secretion of interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α. Furthermore, the cellular redox imbalance and inflammation induced by LPS were reversed by inhibiting P53 activity. P53 expression followed by LPS-induced inflammation was also be restricted by suppressing ROS generation. The present study shows that LPS-induced inflammation in HGFs is partially dependent on P53 modulating ROS and ROS stimulating P53, which suggests that P53 and ROS may form a feedback loop. The identification of this mechanism may provide potential new therapeutic strategies for periodontitis.

In vivo Proinflammatory Cytokine Production by CD-1 Mice in Response to Equipotential Doses of Rhodobacter capsulatus PG and Salmonella enterica Lipopolysaccharides.

The capacities of relatively nontoxic lipopolysaccharide (LPS) from Rhodobacter capsulatus PG and highly potent LPS from Salmonella enterica serovar Typhimurium to evoke proinflammatory cytokine production have been compared in vivo. Intravenous administration of S. enterica LPS at a relatively low dose (1 mg/kg body weight) led to upregulation of TNF-α, IL-6, and IFN-γ production by non-sensitized CD-1 mice. LPS from R. capsulatus PG used at a four-times higher dose than that from S. enterica elicited production of almost the same amount of systemic TNF-α; therefore, the doses of 4 mg/kg LPS from R. capsulatus PG and 1 mg/kg LPS from S. enterica were considered to be approximately equipotential doses with respect to the LPS-dependent TNF-α production by CD-1 mice. Rhodobacter capsulatus PG LPS was a weaker inducer of the production of TNF-α, IL-6, and IFN-γ, as compared to the equipotential dose of S. enterica LPS. Administration of R. capsulatus PG LPS before S. enterica LPS decreased production of IFN-γ, but not of TNF-α and IL-6, induced by S. enterica LPS. Rhodobacter capsulatus PG LPS also suppressed IFN-γ production induced by S. enterica LPS when R. capsulatus PG LPS had been injected as little as 10 min after S. enterica LPS, but to a much lesser extent. Rhodobacter capsulatus PG LPS did not affect TNF-α and IL-6 production induced by the equipotential dose of S. enterica LPS. In order to draw conclusion on the endotoxic activity of particular LPSs, species-specific structure or arrangement of the animal or human immune systems should be considered.

The effect of Porphyromonas gingivalis Lipopolysaccharide (LPS) on Rat Brain Microglia Classical and Alternative Activation in vitro: MMP‐9 generation

BackgroundThe putative association between periodontal disease (PD), a chronic inflammatory disease affecting 64% of adults 65 years and older, and neuroinflammation, a condition which involves microglia, a cell of the brain innate immune system, remains relatively unexplored. We recently reported that lipopolysaccharide (LPS) of Porphyromonas gingivalis (Pg), a pathogenic bacteria implicated in periodontitis activates both classical (M1‐type) and alternative (M2‐type) activation of neonatal rat microglia (BMG) and concomitant release of superoxide anion, thromboxane B2, cytokines, and chemokines (Toxicological Sciences Supplement, 150 (1), Abstract # 2974, 2017). We hypothesized that classical activated microglia might also release the pro‐inflammatory matrix metalloproteinase‐9 (MMP‐9).MethodsP. gingivalis LPS (Pg LPS) was purchased from InvivoGen (San Diego, CA). E. coli LPS (Ec LPS) 026:B6 (from Difco Lab, Detroit, MI) was used as a positive control. BMG were isolated from neonatal rats, and treated in vitro with either Pg LPS or Ec LPS, in a concentration‐dependent manner, for 18 hours at 35.9°C. BMG were identified by confocal microscopy using the surface marker CD11b/c. Matrix metalloproteinase‐9 was determined with a rat total MMP‐9 DuoSet ELISA kit (R&amp;D Systems).ResultsStatistically significant and concentration‐dependent release of pro‐inflammatory MMP‐9 was observed at &gt; than 1ng/mL Ec LPS and 105 ng/mL Pg LPS.ConclusionsOur results provide support for our working hypothesis, because Pg LPS stimulated BMGs to release pro‐inflammatory MMP‐9 in a time‐ and concentration‐dependent manner. Thus, our current observations extend our studies on the effect of Pg LPS on rat brain microglia activation and contribute to further characterize both periodontitis, and the role of BMG in neuroinflammation and potential neurodegeneration.Support or Funding InformationSupport by College of Dental Medicine, Midwestern University is gratefully acknowledged.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

β-carotene suppresses Porphyromonas gingivalis lipopolysaccharide-mediated cytokine production in THP-1 monocytes cultured with high glucose condition.

Periodontitis is associated with development of diabetes mellitus. Although lipopolysaccharide (LPS) of Porphyromonas gingivalis (Pg), a major pathogen of periodontitis, may lead the progression of diabetes complications, the precise mechanisms are unclear. We, therefore, investigated the effects of β-carotene on production of Pg LPS-induced inflammatory cytokines in human monocytes cultured high glucose (HG) condition. THP-1 cells were cultured under 5.5 mM or 25 mM glucose conditions, and cells were stimulated with Pg LPS. To investigate the productivity of TNF-α, IL-6, and MCP-1, cell supernatants were collected for ELISA. To examine the effects of NF-kB signals on cytokine production, Bay11-7082 was used. HG enhanced Pg LPS-induced production of TNF-α, IL-6, and MCP-1 via NF-kB signals in THP-1. β-carotene suppressed the enhancement of the Pg LPS-induced cytokine production in THP-1 via NF-κB inactivation. Our results suggest that β-carotene might be a potential anti-inflammatory nutrient for circulating Pg LPS-mediated cytokine production in diabetic patients with periodontitis.

Metformin Inhibits Porphyromonas gingivalis Lipopolysaccharide-Influenced Inflammatory Response in Human Gingival Fibroblasts via Regulating Activating Transcription Factor-3 Expression.

Chronic periodontitis, one of the most prevalent oral diseases, is associated with Porphyromonas gingivalis (Pg) lipopolysaccharide (LPS) infection and has profound effects on type 2 diabetes mellitus (t2DM). Metformin, a well-known antidiabetic agent, has been reported to exert anti-inflammatory effects on various cells. This study aims to investigate the role of metformin on LPS-influenced inflammatory response in human gingival fibroblasts (HGFs). Dose-dependent additive effects of metformin on LPS-influenced HGFs were detected. Cell-counting assay was used to determine effects of metformin and LPS on viability of HGFs. Enzyme-linked immunosorbent assay and quantitative real-time polymerase chain reaction (qRT-PCR) were applied to detect levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in differently treated cells. Activating transcription factor-3 (ATF3) small interfering (si)RNA transfection was used to determine the mechanism of metformin action, and the transfection efficiency was observed by fluorescence microscope. Effects of ATF3 knockdown were determined by qRT-PCR and Western blot. Results showed that 5 μg/mL Pg LPS and 0.1, 0.5, and 1 mM metformin exhibited no toxicity to HGFs, and metformin inhibited LPS-influenced IL-1β, IL-6, and TNF-α production in a dose-dependent manner. Metformin and LPS could synergistically facilitate ATF3 expression, and ATF3 knockdown abolished inhibitory effects of metformin on LPS-influenced inflammatory cytokine production in HGFs. The present study confirms that metformin suppresses LPS-enhanced IL-6, IL-1β, and TNF-α production in HGFs via increasing ATF3 expression.

Study on the role of NALP3 inflammasome in Porphyromonas gingivalis lipopolysaccharide induced RAW264.7

Objective: To illuminate the effect of NALP3 inflammasome on regulating the expression of cytokines of macrophages in periodontitis. Methods: RAW264.7 cells were cultured and divided into three groups. The first group stayed normal as control, the second group was stimulated by 1 mg/L Porphyromonas gingivalis (Pg) lipopolysaccharide (LPS), the third group was pretreated with AC-YVAD-CMK (caspase-1 inhibitor) before stimulated with 1 mg/L Pg LPS. RAW264.7 cells pretreated with various concentrations (0, 5, 10, 25, 50, 75, 100, 200 μmol/L) of AC-YVAD-CMK for 2 h, and stimulated by 1 mg/L Pg LPS for 24 h in the third group. After that, cell survival rate were detected by cell counting kit-8. Every group cells gene transcription of NALP3 and interleukin-1β (IL-1β) were detected by quantitative real-time PCR (qPCR) after 6 h, protein expression of NALP3 and IL-1β were separately detected by Western blotting and enzyme linked immunosorbent assay (ELISA) after 24 h, respectively. Results: It is observed that treatment with 5, 10, 25, 50, 75, 100, 200 μmol/L AC-YVAD-CMK did not significantly affect the viability of RAW264.7 cells. qPCR showed that mRNA expression of IL-1β level (1.03±0.08, 5.48±0.22, 4.31±0.20) and NALP3 level (0.96±0.05, 2.62±0.44, 1.73±0.09). Western blotting showed that protein expression of NALP3 level (1.00±0.10, 2.34±0.04, 1.64±0.04), ELISA showed protein secretion of IL-1β level ([40.20±0.25], [61.50±1.81], [52.40±1.91] ng/L). After stimulated by Pg LPS, mRNA and protein expression of IL-1β (P<0.01, P<0.01) and NALP3 (P<0.01, P<0.01) significantly increased; but the expression of IL-1β (P=0.002, P=0.027) and NALP3 (P<0.01, P<0.01) were decreased when pretreated with AC-YVAD-CMK. Conclusions: NALP3 inflammasome signal pathway can be activated by Pg LPS in RAW264.7. Block of the pathway can inhibit Pg LPS-induced secretion of cytokines.

Lipopolysaccharide and IL-1β coordinate a synergy on cytokine production by upregulating MyD88 expression in human gingival fibroblasts.

Both lipopolysaccharide (LPS) and interleukin (IL)-1β activate the MyD88-dependent signaling pathways to stimulate proinflammatory cytokine expression. However, it remains unknown how LPS and IL-1β interact with each other to coordinate the stimulation. In this study, we sought to investigate the interaction between LPS and IL-1β on MyD88-dependent signaling pathways in human gingival fibroblasts (HGFs). Results showed that LPS derived from Porphyromonas gingivalis (Pg LPS) and IL-1β cooperatively stimulated mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NFκB) signaling pathways, and subsequent expression of proinflammatory cytokine expression. Furthermore, our results showed that Pg LPS and IL-1β exerted a synergy on MyD88 expression and knockdown of MyD88 expression by small interfering RNA diminished the synergistic effect of Pg LPS and IL-1β on IL-6 expression, suggesting that upregulation of MyD88 is involved in the coordinated stimulation by Pg LPS and IL-1β of proinflammatory cytokine expression. Finally, our results showed that pharmacological inhibitors for MAPK and NFκB significantly reduced IL-6 secretion stimulated by Pg LPS and IL-1β, indicating that the MyD88-dependent MAPK and NFκB signaling pathways are essential for the upregulation of proinflammatory cytokine expression by Pg LPS and IL-1β. Taken together, this study showed that LPS and IL-1β coordinate a synergy on cytokine production by upregulating MyD88 expression in HGFs.