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Carnosic acid (CA), which is one of bioactive compounds from rosemary, has various biological activities. However, the effect of CA on periodontal ligament cells is still uncertain. The aim of this study was to examine the effects of CA on inflammatory cytokines production in human periodontal ligament cells.Cytokine and chemokine levels were measured by ELISA. Activations of signal transduction pathway were determined by Western blotting.Treatment of CA decreased inflammatory cytokines such as interleukin (IL)-6, CXC chemokine ligand (CXCL)10, CC chemokine ligand (CCL)2, and CCL20 productions in IL-1β or tumor necrosis factor (TNF)-α-stimulated human periodontal ligament cells in a dose-dependent manner. Moreover, we found that CA could suppress Jun-N-terminal kinase (JNK) pathway, nuclear factor (NF)-κB pathway and signal transducer and activator of transcription (STAT)3 pathway activation in IL-1β or TNF-α-stimulated human periodontal ligament cells.The results of this study suggest that CA has anti-inflammatory effects in human periodontal ligament cells by inhibiting JNK, NF-κB and STAT3 pathways.

Sudachitin, a polymethoxylated flavonoid found in the skin of Citrus sudachi, is a biologically active substance. The aim of this study was to examine whether sudachitin could be used to inhibit the expression of matrix metalloproteinase (MMP)-1 and MMP-3, which are involved in the destruction of periodontal tissues in periodontal lesions, in tumor necrosis factor (TNF)-α-stimulated human periodontal ligament cells (HPDLC). Sudachitin suppressed TNF-α-induced MMP-1 and MMP-3 production in HPDLC. On the other hand, it enhanced tissue inhibitor of metalloproteinase (TIMP)-1 expression. The level of Akt phosphorylation in the TNF-α-stimulated HPDLC was decreased by sudachitin treatment. Moreover, an Akt inhibitor reduced MMP-1 and MMP-3 production and increased TIMP-1 production. These findings indicate that sudachitin reduces MMP-1 and MMP-3 production in TNF-α-stimulated HPDLC by inhibiting the Akt pathway.

The immune response in periodontal lesions is involved in the progression of periodontal disease. Therefore, it is important to find a bioactive substance that has anti-inflammatory effects in periodontal lesions. This study aimed to examine if nobiletin, which is found in the peel of citrus fruits, could inhibit inflammatory responses in interleukin (IL)-1β-stimulated human periodontal ligament cells (HPDLCs). The release of cytokines (IL-6, IL-8, CXCL10, CCL20, and CCL2) and matrix metalloproteinases (MMP-1 and MMP-3) was assessed by ELISA. The expression of cell adhesion molecules (ICAM-1and VCAM-1) and the activation of signal transduction pathways (nuclear factor (NF)-κB, mitogen-activated protein kinases (MAPKs) and protein kinase B (Akt)) in HPDLCs were detected by Western blot analysis.&nbsp, Our experiments revealed that nobiletin decreased the expression of inflammatory cytokines, cell adhesion molecules, and MMPs in IL-1β-stimulated HPDLCs. Moreover, we revealed that nobiletin treatment could suppress the activation of the NF-κB, MAPKs, and Akt pathways. These findings indicate that nobiletin could inhibit inflammatory reactions in IL-1β-stimulated HPDLCs by inhibiting multiple signal transduction pathways, including NF-κB, MAPKs, and Akt.

During the Archean (4.0–2.5 Ga), atmospheric oxygen levels would have been much lower than the present value (pO2 < ~10–5 PAL) [1], and the majority of the primary production would have been carried by anoxygenic photosynthetic bacteria. In a sufficiently reducing atmosphere (CH4/CO2 > ~0.2) [2], the layer of hydrocarbon haze could be formed in the upper atmosphere, possibly affecting the climate. Because haze particles significantly absorb the solar UV flux, the formation of hydrocarbon haze could affect the marine microbial ecosystem via the change in the production rate of electron donors (H2 and CO). However, how the formation of hydrocarbon haze affects the global activity of the marine microbial ecosystem remains unclear. Here, we employ a novel carbon cycle model in which a one-dimensional photochemical model “Atmos” [2], a marine microbial ecosystem model, and the carbonate-silicate geochemical cycle model are coupled. We assessed the effect of the formation of hydrocarbon haze on marine microbial ecosystems assuming completely anoxic conditions (pO2 < ~10–10 PAL) in the middle Archean and assuming mildly oxidized conditions (pO2 > 10–10 PAL) in the late Archean.We found that, under the completely anoxic condition, haze formation works as a negative feedback for the oceanic biological activity. This is because the formation rate of electron donors (H2 and CO) in the atmosphere decreases with the progress of haze formation, so that the changes in the biogenic methane flux and the haze formation rate are suppressed. More specifically, the decrease in the formation rate of electron donors is caused by the decrease in the photo-dissociation rate of CO2 because of UV-shielding due to haze particles, and also by removal of C- and H-atom, which are supposed to be converted to CO and H2 if the haze is not formed, due to rainout of haze particles. We also found that, under the mildly oxidized condition, there are multiple equilibrium climate states that have a different haze thickness. The solution with thicker haze layer is similar to the completely anoxic condition, however, the other solution with the thinner haze layer is unique to the mildly oxidized condition. In this new equilibrium state, the formation rate of electron donors further decreases with the progress of haze formation because of the decrease in the photo-dissociation rate of formaldehyde. Thus, this mechanism works as a strong negative feedback for ocean biological activity and haze thickness, keeping the haze thickness thinner than the completely anoxic condition. We show that, as a result of this negative feedback, climate with the thinner haze could be stably achieved under the mildly oxidized condition. This result is consistent with a geological record which suggests possible transient formation of the haze in the Late Archean [3]. We suggest that haze formation is a vital process in understanding the biological activity and climate stability on terrestrial Earth-like planets.[1] Lyons et al. (2014). Nature 506, 307-315. [2] Arney et al. (2016). Astrobiology 16(11), 873-899. [3] Izon et al. (2017). PNAS 114(13), E2571-E2579.

Earth's modern atmosphere is highly oxygenated and is a remotely detectable signal of its surface biosphere. However, the lifespan of oxygen-based biosignatures in Earth's atmosphere remains uncertain, particularly for the distant future. Here we use a combined biogeochemistry and climate model to examine the likely timescale of oxygen-rich atmospheric conditions on Earth. Using a stochastic approach, we find that the mean future lifespan of Earth's atmosphere with oxygen levels more than 1% of the present atmospheric level is 1.08+-0.14 billion years. The model projects that a deoxygenation of the atmosphere, with atmospheric oxygen dropping sharply to levels reminiscnet of the Archaean Earth, will most probably be triggered before the inception of moist greenhouse conditions in Earth's climate system and before the extensive loss of surface water from the atmosphere. We find that future deoxygenation is an inevitable consequence of increasing solar fluxes, whereas its precise timing is modulated by the exchange flux of reducing power between the mantle and the ocean-atmosphere-crust system. Our results suggest that the planetary carbonate-silicate cycle will tend to lead to terminally CO2-limited biospheres and rapid atmospheric deoxygenation, emphasizing the need for robust atmospheric biosignatures applicable to weakly oxygenated and anoxic exoplanet atmospheres and highlighting the potential importance of atmospheric organic haze during the terminal stages of planetary habitability., Manuscript currently in press in Nature Geoscience

Sudachitin, which is a polymethoxylated flavonoid found in the peel of Citrus sudachi, has some biological activities. However, the effect of sudachitin on periodontal resident cells is still uncertain. The aim of this study was to examine if sudachitin could decrease the expression of inflammatory mediators such as cytokines, chemokines, or matrix metalloproteinase (MMP) in interleukin- (IL-) 1β-stimulated human periodontal ligament cells (HPDLC). Sudachitin inhibited IL-1β-induced IL-6, IL-8, CXC chemokine ligand (CXCL)10, CC chemokine ligand (CCL)2, MMP-1, and MMP-3 production in HPDLC. On the other hand, tissue inhibitor of metalloproteinase- (TIMP-) 1 expression was increased by sudachitin treatment. Moreover, we found that the nuclear factor- (NF-) κB and protein kinase B (Akt) pathways in the IL-1β-stimulated HPDLC were inhibited by sudachitin treatment. These findings indicate that sudachitin is able to reduce inflammatory mediator production in IL-1β-stimulated HPDLC by inhibiting NF-κB and Akt pathways.

Nobiletin, a biologically active substance in the skin of citrus fruits, has been reported to be an effective anti-inflammatory, anticancer, and antimicrobial agent. In this study, we aimed to examine the anti-inflammatory effects of nobiletin on tumor necrosis factor- (TNF-) stimulated human periodontal ligament cells (HPDLCs). Our results demonstrated that nobiletin treatment could decrease the expressions of inflammatory cytokines (C-X-C motif chemokine ligand (CXCL)10, C-C motif chemokine ligand (CCL)2, and interleukin- (IL-) 8), matrix metalloproteinases (MMPs) (MMP1 and MMP3), and prostaglandin-endoperoxide synthase 2 (PTGS2) in TNF-stimulated HPDLCs. Moreover, we revealed that nobiletin could inhibit the activation of nuclear factor- (NF-) κB and protein kinase B (AKT1) pathways in TNF-stimulated HPDLCs. Furthermore, nobiletin treatment enhanced nuclear factor, erythroid 2 like 2 (NFE2L2) and heme oxygenase 1 (HMOX1) expressions in TNF-stimulated HPDLCs. In conclusion, these findings suggest that nobiletin can inhibit inflammatory responses in TNF-stimulated HPDLCs by inhibiting NF-κB and AKT1 activations and upregulating the NFE2L2 and HMOX1 expression.

Carnosic acid, which is a bioactive compound isolated from rosemary, has various pharmacological effects. However, the anti-inflammatory effect of carnosic acid on periodontitis is still unknown. The aim of this study was to investigate the effect of carnosic acid on CXC chemokine receptor 3 (CXCR3) ligands, which are involved in Th1 cells migration and accumulation, production in interleukin (IL)-27-stimulated human oral epithelial cells (TR146 cells). Carnosic acid decreased CXC chemokine ligand (CXCL)9, CXCL10, and CXCL11 production in IL-27-stimulated TR146 cells in a dose-dependent fashion. Moreover, we disclosed that carnosic acid could suppress signal transducer and activator of transcription (STAT)1, STAT3, and protein kinase B (Akt) phosphorylation in IL-27-stimulated TR146 cells. Furthermore, STAT1, STAT3, and Akt inhibitors could suppress CXCR3 ligands production in IL-27-treated TR146 cells. In summary, carnosic acid could reduce CXCR3 ligands production in human oral epithelial cell by inhibiting STAT1, STAT3, and Akt activation.

Objectives: The effects of 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymer on the adherence of microorganisms such as non-Candida albicans Candida (NCAC) and methicillin-resistant Staphylococcus aureus (MRSA), frequently detected in oral infections in immunocompromised and/or elderly people, to denture resin material, are still unclear. Here, we report the effects of MPC-polymer on the adherence of C. albicans, NCAC, and MRSA to acrylic denture resin. Methods: Sixteen strains of C. albicans, seven strains of C. glabrata, two strains of C. tropicalis, one strain of C. parapsilosis, and six strains of MRSA were used. We cultured the fungal/bacterial strains and examined the cell growth and adherence of fungi/bacteria to mucin-coated acrylic denture resin plates (ADRP) with or without MPC-polymer coating, by scanning electron microscopy. The cell surface hydrophobicity of the fungal/bacterial strains was measured by the adsorption to hydrocarbons. Results: MPC-polymer did not affect the growth of all strains of Candida species and MRSA, but significantly suppressed adherence to ADRP in most strains of C. albicans and all strains of NCAC and MRSA. A significant positive correlation was found between cell hydrophobicity and the reduction rates of microbial adherence to ADRP treated with 5% of MPC-polymer. Conclusions: MPC-polymer treatment for acrylic resin material suppresses the adherence of C. albicans, NCAC and MRSA via their hydrophilicity interaction. Clinical significance: The application of MPC-polymer for denture hygiene is potent to prevent oral candidiasis, denture stomatitis and opportunistic infection, caused by Candida species and MRSA, via suppressing the adherence of those fungus/bacteria.

Earth's ocean-atmosphere system has undergone a dramatic but protracted increase in oxygen (O2) abundance. This environmental transition ultimately paved the way for the rise of multicellular life and provides a blueprint for how a biosphere can transform a planetary surface. However, estimates of atmospheric oxygen levels for large intervals of Earth's history still vary by orders of magnitude-foremost for Earth's middle history. Historically, estimates of mid-Proterozoic (1.9-0.8 Ga) atmospheric oxygen levels are inferred based on the kinetics of reactions occurring in soils or in the oceans, rather than being directly tracked by atmospheric signatures. Rare oxygen isotope systematics-based on quantifying the rare oxygen isotope 17O in addition to the conventionally determined 16O and 18O-provide a means to track atmospheric isotopic signatures and thus potentially provide more direct estimates of atmospheric oxygen levels through time. Oxygen isotope signatures that deviate strongly from the expected mass-dependent relationship between 16O, 17O, and 18O develop during ozone formation, and these "mass-independent" signals can be transferred to the rock record during oxidation reactions in surface environments that involve atmospheric O2. The magnitude of these signals is dependent upon pO2, pCO2, and the overall extent of biospheric productivity. Here, we use a stochastic approach to invert the mid-Proterozoic Δ17O record for a new estimate of atmospheric pO2, leveraging explicit coupling of pO2 and biospheric productivity in a biogeochemical Earth system model to refine the range of atmospheric pO2 values that is consistent with a given observed Δ17O. Using this approach, we find new evidence that atmospheric oxygen levels were less than ∼1% of the present atmospheric level (PAL) for at least some intervals of the Proterozoic Eon.

Transforming growth factor (TGF)-β1 is a multifunctional cytokine, which can control certain functions of various kinds of cells. However, it is unclear whether TGF-β1 affects T-cell migration in periodontal lesions. The aim of this study was to examine the effects of TGF-β1 on the production of C-C chemokine ligand (CCL)11, which is a T-helper 2-type chemokine, in human periodontal ligament cells (HPDLC). Interleukin (IL)-4 induced CCL11 production, but TGF-β1 did not, in HPDLC. However, TGF-β1 enhanced CCL11 production in IL-4-stimulated HPDLC. Western blot analysis showed that the signal transducer and activator of transcription 6 (STAT6) pathway was highly activated in HPDLC that had been stimulated with both IL-4 and TGF-β1. Mitogen-activated protein kinase activation did not differ between the HPDLC treated with a combination of IL-4 and TGF-β1 and those treated with IL-4 or TGF-β1 alone. Moreover, a STAT6 inhibitor significantly inhibited CCL11 production in HPDLC that had been stimulated with IL-4 and TGF-β1. The current study clearly demonstrated that TGF-β1 enhanced IL-4-induced CCL11 production in HPDLC. The STAT6 pathway is important for CCL11 production in IL-4- and TGF-β1-treated HPDLC.

The evolution of different forms of photosynthetic life has profoundly altered the activity level of the biosphere, radically reshaping the composition of Earth's oceans and atmosphere over time. However, the mechanistic impacts of a primitive photosynthetic biosphere on Earth's early atmospheric chemistry and climate are poorly understood. Here, we use a global redox balance model to explore the biogeochemical and climatological effects of different forms of primitive photosynthesis. We find that a hybrid ecosystem of H2-based and Fe-based anoxygenic photoautotrophs - organisms that perform photosynthesis without producing oxygen - gives rise to a strong nonlinear amplification of Earth's methane (CH4) cycle, and would thus have represented a critical component of Earth's early climate system before the advent of oxygenic photosynthesis. Using a Monte Carlo approach, we find that a hybrid photosynthetic biosphere widens the range of geochemical conditions that allow for warm climate states well beyond either of these metabolic processes acting in isolation. Our results imply that Earth's early climate was governed by a novel and poorly explored set of regulatory feedbacks linking the anoxic biosphere and the coupled H, C and Fe cycles. We suggest that similar processes should be considered when assessing the potential for sustained habitability on Earth-like planets with reducing atmospheres., Comment: Accepted to Nature Geoscience; Final article and Supplementary Information available at https://www.nature.com/articles/s41561-017-0031-2

Background/Aims: Interleukin-27 (IL-27) is a cytokine which belongs to the IL-12 family. However, the role of IL-27 in the pathogenesis of periodontal disease is uncertain. The aim of this study was to examine the effect of IL-27 on chemokine production in TNF-α-stimulated human oral epithelial cells (TR146). Methods: We measured chemokine production in TR146 by ELISA. We used western blot analysis to detect the phosphorylation levels of signal transduction molecules, including STAT1 and STAT3 in TR146. We used inhibitors to examine the role of STAT1 and STAT3 activation. Results: IL-27 increased CXCR3 ligands production in TNF-α-stimulated TR146. Meanwhile, IL-27 suppressed IL-8 and CCL20 production induced by TNF-α. STAT1 phosphorylation level in IL-27 and TNF-α-stimulated TR146 was enhanced in comparison to TNF-α-stimulated TR146. STAT3 phosphorylation level in IL-27-treated TR146 did not change by TNF-α. Both STAT1 inhibitor and STAT3 inhibitor decreased CXCR3 ligands production. STAT1 inhibitor overrode the inhibitory effect of IL-27 on IL-8 and CCL20 production in TNF-α-stimulated TR146. Meanwhile, STAT3 inhibitor did not modulate IL-8 and CCL20 production. Conclusion: IL-27 might control leukocyte migration in periodontal lesion by modulating chemokine production from epithelial cells.

The double-stranded RNA-dependent kinase (PKR), which is activated by double stranded RNA, induces inflammation by regulating NF-κB signaling. The NLR family pyrin domain-containing 3 (NLRP3) inflammasome also modulates inflammation in response to infection. Porphyromonas gingivalis (P.gingivalis) is an oral bacterium which is implicated in the pathogenesis of periodontal diseases. We previously reported that PKR is a key modulator of bone metabolism and inflammation in the periodontal tissue. PKR was also reported to induce inflammation in response to microbes by regulating the NLRP3 inflammasome, suggesting that PKR could affect inflammation along with NLRP3 in periodontal diseases. In this study, we investigated the effects of PKR on NLRP3 expression and NF-κB activity in P. gingivalis infected osteoblasts. We first constructed a SNAP26b-tagged P.gingivalis (SNAP-P. g.) and traced its internalization into the cell. SNAP-P. g. increased the activity of PKR and NF-κB and also induced NLRP3 expression in osteoblasts. Inhibition of NF-κB attenuated SNAP-P. g.-induced NLRP3 expression. The knockdown of PKR using shRNA decreased both the activity of NF-κB and the expression of NLRP3 induced by SNAP-P.g.. We therefore concluded that in osteoblasts, P. gingivalis activated PKR, which in turn increased NLRP3 expression by activating NF-κB. Our results suggest that PKR modulates inflammation by regulating the expression of the NLRP3 inflammasome through the NF-κB pathway in periodontal diseases.

The macronutrient phosphorus is thought to limit primary productivity in the oceans on geological timescales. Although there has been a sustained effort to reconstruct the dynamics of the phosphorus cycle over the past 3.5 billion years, it remains uncertain whether phosphorus limitation persisted throughout Earth's history and therefore whether the phosphorus cycle has consistently modulated biospheric productivity and ocean-atmosphere oxygen levels over time. Here we present a compilation of phosphorus abundances in marine sedimentary rocks spanning the past 3.5 billion years. We find evidence for relatively low authigenic phosphorus burial in shallow marine environments until about 800 to 700 million years ago. Our interpretation of the database leads us to propose that limited marginal phosphorus burial before that time was linked to phosphorus biolimitation, resulting in elemental stoichiometries in primary producers that diverged strongly from the Redfield ratio (the atomic ratio of carbon, nitrogen and phosphorus found in phytoplankton). We place our phosphorus record in a quantitative biogeochemical model framework and find that a combination of enhanced phosphorus scavenging in anoxic, iron-rich oceans and a nutrient-based bistability in atmospheric oxygen levels could have resulted in a stable low-oxygen world. The combination of these factors may explain the protracted oxygenation of Earth's surface over the last 3.5 billion years of Earth history. However, our analysis also suggests that a fundamental shift in the phosphorus cycle may have occurred during the late Proterozoic eon (between 800 and 635 million years ago), coincident with a previously inferred shift in marine redox states, severe perturbations to Earth's climate system, and the emergence of animals.

Gomisin N, which is a lignan isolated from Schisandra chinensis, has some pharmacological effects. However, the anti-inflammatory effects of gomisin N on periodontal disease are uncertain. The aim of this study was to examine the effect of gomisin N on inflammatory mediator production in tumor necrosis factor (TNF)-α-stimulated human periodontal ligament cells (HPDLC). Gomisin N inhibited interleukin (IL)-6, IL-8, CC chemokine ligand (CCL) 2, and CCL20 production in TNF-α-stimulated HPDLC in a dose-dependent manner. Moreover, we revealed that gomisin N could suppress extracellular signal-regulated kinase (ERK) and c-Jun N terminal kinase (JNK) phosphorylation in TNF-α-stimulated HPDLC though protein kinase B (Akt) phosphorylation was not suppressed by gomisin N treatment. In summary, gomisin N might exert anti-inflammatory effects by attenuating cytokine production in periodontal ligament cells via inhibiting the TNF-α-stimulated ERK and JNK pathways activation.

Alkannin, which is found in Alkanna tinctoria, a member of the borage family, is used as a food coloring. Alkannin has recently been reported to have certain biological functions, such as anti-microbial and anti-oxidant effects. It is known that CC chemokine receptor (CCR) 5-positive leukocytes contribute to alveolar bone resorption in periodontal lesions. The aim of this study was to examine whether alkannin inhibits the production of CC chemokine ligand (CCL) 3 and CCL5, which are CCR5 ligands, in human periodontal ligament cells (HPDLC). Interleukin (IL)-1β induced CCL3 and CCL5 production in HPDLC. Alkannin inhibited IL-1β-mediated CCL3 and CCL5 production in HPDLC in a dose-dependent manner. Moreover, we revealed that alkannin suppressed inhibitor of kappa B-α degradation in IL-1β-stimulated HPDLC. In addition, a nuclear factor (NF)-κB inhibitor significantly inhibited CCL3 and CCL5 production in IL-1β-stimulated HPDLC. These results demonstrate that alkannin inhibits CCR5 ligand production in IL-1β-stimulated HPDLC by attenuating the NF-κB signaling pathway.

Atmospheric oxygen levels increased in two stages. This two-step rise of oxygen may be a natural consequence of lowered oxidative capacity caused by the emergence of felsic continents and the growth of a continental carbon reservoir.

Silicon photomultipliers (SiPMs) have a low radioactivity, compact geometry, low operation voltage, and reasonable photo-detection efficiency for vacuum ultraviolet light (VUV). Therefore it has the potential to replace photomultiplier tubes (PMTs) for future dark matter experiments with liquid xenon (LXe). However, SiPMs have nearly two orders of magnitude higher dark count rate (DCR) compared to that of PMTs at the LXe temperature ($\sim$ 165 K). This type of high DCR mainly originates from the carriers that are generated by band-to-band tunneling effect. To suppress the tunneling effect, we have developed a new SiPM with lowered electric field strength in cooperation with Hamamatsu Photonics K. K. and characterized its performance in a temperature range of 153 K to 298 K. We demonstrated that the newly developed SiPMs had 6--54 times lower DCR at low temperatures compared to that of the conventional SiPMs., 9 pages,13 figures, 2 tables

The oceanic redox state has played an essential role in the evolution of life on earth, and oceanic “anoxic events” have been proposed as one of the causal mechanisms for mass extinctions. During the mid-Cretaceous, oceanic anoxic events (OAEs) occurred several times and had a substantial impact on the biosphere. Planktic foraminifers are marine planktons with calcite tests, and their shells constitute approximately 30%–80% of modern deep-marine calcite; thus, they play a key role in the global carbon cycle. Previous studies have reported that at, or near, the times of major Cretaceous OAEs, planktic foraminifers have a high turnover (extinction and speciation) rate. However, the precise impact of anoxic conditions on the evolutionary trend of planktic foraminifers remained obscure. In this study, we investigate this by assessing the extinction/speciation rate of planktic foraminifers around OAEs. Our results suggest that the development of anoxia during OAEs would not have had a direct effect on the evolutionary trend (i.e., species number and turnover ratio). Two foraminiferal turnovers occurred around OAE1a and OAE2, however, all five turnover peaks seem to be largely associated with a relatively short-term (0.5–3 Myr) eustatic curve. Decreasing species numbers of planktic foraminifers are associated with a relatively lower sea eustatic level (second-order; ~20 Myr) and a small latitudinal temperature gradient around OAE1b, which are not anoxic conditions. Changes in oceanographical parameters (i.e., surface biological productivity, water column structure, carbonate chemistry, and nutrients) related to lowering sea-levels might have had a significant effect on foraminiferal evolutionary trends.

Some atmospheric gases have been proposed as counter indicators to the presence of life on an exoplanet if remotely detectable at sufficient abundance (i.e., antibiosignatures), informing the search for biosignatures and potentially fingerprinting uninhabited habitats. However, the quantitative extent to which putative antibiosignatures could exist in the atmospheres of inhabited planets is not well understood. The most commonly referenced potential antibiosignature is CO, because it represents a source of free energy and reduced carbon that is readily exploited by life on Earth and is thus often assumed to accumulate only in the absence of life. Yet, biospheres actively produce CO through biomass burning, photooxidation processes, and release of gases that are photochemically converted into CO in the atmosphere. We demonstrate with a 1D ecosphere-atmosphere model that reducing biospheres can maintain CO levels of ~100 ppmv even at low H2 fluxes due to the impact of hybrid photosynthetic ecosystems. Additionally, we show that photochemistry around M dwarf stars is particularly favorable for the buildup of CO, with plausible concentrations for inhabited, oxygen-rich planets extending from hundreds of ppm to several percent. Since CH4 buildup is also favored on these worlds, and because O2 and O3 are likely not detectable with the James Webb Space Telescope, the presence of high CO (>100 ppmv) may discriminate between oxygen-rich and reducing biospheres with near-future transmission observations. These results suggest that spectroscopic detection of CO can be compatible with the presence of life and that a comprehensive contextual assessment is required to validate the significance of potential antibiosignatures., 10 pages, 5 figures, 2 tables. Published Open Access in ApJ

Outer membrane vesicles (OMVs) are nanosized particles derived from the outer membrane of gram-negative bacteria. Oral bacterium Porphyromonas gingivalis (Pg) is known to be a major pathogen of periodontitis that contributes to the progression of periodontal disease by releasing OMVs. The effect of Pg OMVs on systemic diseases is still unknown. To verify whether Pg OMVs affect the progress of diabetes mellitus, we analyzed the cargo proteins of vesicles and evaluated their effect on hepatic glucose metabolism. Here, we show that Pg OMVs were equipped with Pg-derived proteases gingipains and translocated to the liver in mice. In these mice, the hepatic glycogen synthesis in response to insulin was decreased, and thus high blood glucose levels were maintained. Pg OMVs also attenuated the insulin-induced Akt/glycogen synthase kinase-3 β (GSK-3β) signaling in a gingipain-dependent fashion in hepatic HepG2 cells. These results suggest that the delivery of gingipains mediated by Pg OMV elicits changes in glucose metabolisms in the liver and contributes to the progression of diabetes mellitus.

Honokiol and magnolol, which are lignans isolated from Magnolia quinquepeta, have some pharmacological effects. However, the anti-inflammatory effects of honokiol and magnolol on periodontal disease are still uncertain. The aim of this study was to examine the effect of honokiol and magnolol on CXC chemokine receptor 3 (CXCR3) ligands, which are related with Th1 cell migration, production in interleukin (IL)-27-stimulated human oral epithelial cells (TR146 cells). Honokiol and magnolol inhibited CXC chemokine ligand (CXCL)10 and CXCL11 production in IL-27-stimulated TR146 cells in a dose-dependent manner. Moreover, we revealed that honokiol and magnolol could suppress signal transducer and activator of transcription (STAT)3 and protein kinase B (Akt) phosphorylation in IL-27-stimulated TR146 cells though STAT1 phosphorylation was not suppressed by honokiol and magnolol treatment. Furthermore, STAT3 and Akt inhibitors could suppress CXCR3 ligand production in TR146 cells. In summary, honokiol and magnolol could reduce CXCR3 ligand production in oral epithelial cell by inhibiting STAT3 and Akt activation.

Genipin, the aglycon of geniposide found in gardenia fruit has long been considered for treatment of inflammatory diseases in traditional oriental medicine. Genipin has recently been reported to have some pharmacological functions, such as antimicrobial, antitumor, and anti-inflammatory effects. The aim of this study was to examine whether genipin could modify matrix metalloproteinase (MMP)-1 and MMP-3, which are related to the destruction of periodontal tissues in periodontal lesion, expression in tumor necrosis factor (TNF)-α-stimulated human periodontal ligament cells (HPDLCs). Genipin prevented TNF-α-mediated MMP-1 and MMP-3 productions in HPDLCs. Moreover, genipin could suppress not only extracellular signal-regulated kinase (ERK) and Jun-N-terminal kinase (JNK) phosphorylations but also AMP-activated protein kinase (AMPK) phosphorylation in TNF-α-stimulated HPDLCs. Inhibitors of ERK and AMPK could inhibit both MMP-1 and MMP-3 productions. Moreover, we revealed the ERK inhibitor suppressed AMPK phosphorylation in TNF-α-stimulated HPDLCs. These data provide a new mechanism through which genipin could be used for the treatment of periodontal disease to prevent MMPs expression in periodontal lesion.

Understanding the key factors influencing the global oceanic redox system is crucial to fully explaining the variations in oceanic chemical dynamics that have occurred throughout the Earth's history. In order to elucidate the mechanisms behind these variations on geological timescales, numerical sensitivity experiments were conducted with respect to the partial pressure of atmospheric molecular oxygen ( p O 2 ), the continental shelf area ( A cs ), and the riverine input rate of reactive phosphorus to the oceans ( R P ). The sensitivity experiment for atmospheric p O 2 indicates that pervasive oceanic anoxia and euxinia appear when p O 2 p O 2 are higher than a previous estimate of ~50% PAL (present atmospheric level) due to redox-dependent phosphorus cycling. The sensitivity experiment regarding the shelf area demonstrates that changes in the shelf area during the Phanerozoic significantly affected oceanic oxygenation states by changing marine biogeochemical cycling; a large continental shelf acts as an efficient buffer against oceanic eutrophication and prevents the appearance of ocean anoxia/euxinia. We also found that an enhanced R P is an important mechanism for generation of widespread anoxia/euxinia via expansion of both the oxygen minimum zone and coastal deoxygenation, although the critical R P value depends significantly on p O 2 , A cs , and the redox-dependent burial efficiency of phosphorus at the sediment--water interface. Our systematic examination of the oceanic redox state under Cretaceous greenhouse climatic conditions also supports the above results.

The progressive oxygenation of the Earth’s atmosphere was pivotal to the evolution of life, but the puzzle of when and how atmospheric oxygen (O2) first approached modern levels (~21%) remains unresolved. Redox proxy data indicate the deep oceans were oxygenated during 435-392 Ma, and the appearance of fossil charcoal indicates O2>15-17% by 420-400 Ma. However, existing models have failed to predict oxygenation at this time. Here we show that the earliest plants, which colonized the land surface from ~470 Ma onwards, were responsible for this mid- Paleozoic oxygenation event, through greatly increasing global organic carbon burial – the net long-term source of O2. We use a trait-based ecophysiological model to predict that cryptogamic vegetation cover could have achieved ~30% of today’s global terrestrial net primary productivity by~445 Ma. Data from modern bryophytes suggests this plentiful early plant material had a much higher molar C:P ratio (~2000) than marine biomass (~100), such that a given weathering flux of phosphorus could support more organic carbon burial. Furthermore, recent experiments suggest that early plants selectively increased the flux of phosphorus (relative to alkalinity) weathered from rocks. Combining these effects in a model of long-term biogeochemical cycling, we reproduce a sustained +2‰ increase in the carbonate carbon isotope (δ13C) record by ~445 Ma, and predict a corresponding rise in O2 to present levels by 420-400 Ma, consistent with geochemical data. This oxygen rise represents a permanent shift in regulatory regime to one where fire-mediated negative feedbacks on organic carbon burial stabilise high O2 levels.

Objective Halitosis is caused by volatile sulphur compounds including methyl mercaptan (CH3SH) in the oral cavity and is a serious problem that limits interpersonal social communication. The aim of study was to evaluate the effects of reuterin-related compounds (RRCs) on halitosis-related periodontopathic bacteria in vitro. Materials and Methods RRC-01, RRC-02 and RRC-03 (32 and 64 μg ml−1) in culture media containing Fusobacterium nucleatum JCM8523 and Porphyromonas gingivalis ATCC33277 were used. The effects of RRCs on CH3SH production and detectable odour by F. nucleatum and P. gingivalis were examined by CH3SH production assay and organoleptic test, respectively. The number of bacterial cells was also measured using an ATP assay. In P. gingivalis treated with RRCs, the expression of mgl gene, which is responsible for CH3SH production, was examined by qRT-PCR. Results CH3SH production and the score of detectable odour from F. nucleatum and P. gingivalis culture media containing RRCs were significantly lower than that without RRCs (P

We have examined the impact of the Mesozoic algal revolution using biogeochemical simulations to analyze the energy flux into the subsurface environment. In particular, the delivery scheme of energy to the subsurface was dramatically altered by the appearance of mineralized exoskeletons, both in algal groups (e.g., coccolithophores) and in zooplanktic taxa. These biominerals, acting as ballast, accentuated the delivery of organic matter to subsurface waters. Thus, the elevated organic carbon flux associated with evolutionary developments in Mesozoic taxa caused an intense but short-lived oceanic euxinia, without an associated mass extinction event, in sharp contrast to the relatively prolonged Paleozoic euxinia that were generally coincident with mass extinctions.

CXC chemokine ligand 10 (CXCL10) plays an important role in the infiltration of Th1 cells and thus in the exacerbation of periodontal disease. Theaflavin-3,3'-digallate (TFDG), polyphenol in black tea, has some beneficial effects but the effect of TFDG on CXCL10 production from human gingival fibroblasts (HGFs) is uncertain. In this study, we investigated the mechanisms by which TFDG may inhibit oncostatin M (OSM)-induced CXCL10 production in human gingival fibroblasts. TFDG prevented OSM-mediated CXCL10 production by HGFs in a dose dependent manner. TFDG significantly inhibited OSM-induced phosphorylation of c-Jun N terminal kinase (JNK), protein kinase B (Akt) (Ser473) that are related to CXCL10 production from OSM-stimulated HGFs. In addition, TFDG suppressed OSM receptor (OSMR) β expression on HGFs. These data provide a novel mechanism where the black tea flavonoid, theaflavin, could provide direct benefits in periodontal disease.

CXC chemokine ligand 10 (CXCL10) plays a pivotal role in the recruitment of Th1 cells and, thus, in the development of periodontal disease. Epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), the major catechins derived from green tea, have multiple beneficial effects, but the effects of catechins on CXCL10 production from human gingival fibroblasts (HGFs) is not known. In this study, we investigated the mechanisms by which EGCG and ECG inhibit oncostatin M (OSM)-induced CXCL10 production in HGFs. HGFs constitutively expressed glycoprotein 130 and OSM receptor beta (OSMR beta), which are OSM receptors. OSM increased CXCL10 production in a concentration-dependent manner. EGCG and ECG prevented OSM-mediated CXCL10 production by HGFs. Inhibitors of p38 mitogen-activated protein kinase, c-Jun N-terminal kinase (JNK), phosphatidylinositol-3-OH kinase and signal transducer and activator of transcription (STAT)3 decreased OSM-induced CXCL10 production. EGCG significantly prevented OSM-induced phosphorylation of JNK, Akt (Ser473) and STAT3 (Tyr705 and Ser727). ECG prevented phosphorylation of JNK and Akt (Ser473). In addition, EGCG and ECG attenuated OSMR beta expression on HGFs. These data provide a novel mechanism through which the green tea flavonoids, catechins, can provide direct benefits in periodontal disease.

BACKGROUND AND OBJECTIVE It has been reported that T helper 2 (Th2) cells are related to exacerbation of periodontal disease. However, it is uncertain how the migration of Th2 cells is controlled. In this study, we examined the expression of CC chemokine ligand 17 (CCL17), which is a Th2 chemokine, in periodontal tissues. Moreover, we investigated the effects of cytokines and toll-like receptor (TLR) ligands on the production of CCL17 by human gingival fibroblasts (HGFs). MATERIAL AND METHODS We used immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) to detect CCL17 in periodontal tissues. HGFs were exposed to cytokines and TLR ligands. Expression of CCL17 was examined by RT-PCR and enzyme-linked immunosorbent assay. We used signal transduction inhibitors in some experiments. RESULTS Both CCL17 and its receptor, CC chemokine receptor 4 (CCR4), were expressed in diseased periodontal tissues. A combination of tumour necrosis factor alpha (TNF-alpha) and interleukin (IL)-4/IL-13 increased CCL17 expression. Moreover, treatment of HGFs with a low dose of interferon-gamma (IFN-gamma) in combination with TNF-alpha and IL-4 or IL-13 had synergistic effects on the production of CCL17, whereas a high dose of IFN-gamma inhibited CCL17 production. Furthermore, Escherichia coli (E. coli) lipopolysaccharide (TLR4 ligand) and Pam3CSK4 (TLR2 ligand) inhibited CCL17 production by TNF-alpha + IL-4-stimulated HGFs, while CpG DNA (TLR9 ligand) enhanced TNF-alpha + IL-4 induced-CCL17 production by HGFs. Furthermore, a c-Jun NH2 terminal kinase (JNK) inhibitor, a phosphatidylinositol-3-kinase (PI3K) inhibitor and a nuclear factor kappa B (NF-kappa B) inhibitor inhibited CCL17 production by HGFs. CONCLUSION These results suggest that the CCL17 produced by HGFs may be involved in the migration of Th2 cells into inflamed tissues, and provide evidence that CCL17 production is controlled by cytokines and TLR ligands in periodontal disease.

Vitamin D has important roles on control of calcium and phosphate levels in the body. However, the role of vitamin D on the pathogenesis of periodontal disease is still uncertain. Therefore, we examined the effect of the hormonal form of vitamin D, calcitriol, on inflammatory responses of human periodontal ligament cells (HPDLC). We detected vitamin D receptor expression in non-stimulated HPDLC. Calcitriol inhibited interleukin (IL)-6, IL-8, CC chemokine ligand (CCL) 20, CXC chemokine ligand (CXCL) 10, and matrix metalloproteinase (MMP)-3 release from IL-1β-stimulated HPDLC. Tissue inhibitor of metalloproteinase (TIMP)-1 production did not change by calcitriol. Moreover, we found c-jun N-terminal kinase (JNK) phosphorylation and IκB-α degradation in IL-1β-stimulated HPDLC were inhibited by calcitriol, and JNK and nuclear factor (NF)-κB inhibitors could decrease IL-6, IL-8, CCL20, CXCL10, and MMP-3 productions in IL-1β-treated HPDLC. These findings suggest that vitamin D could modulate inflammatory response in periodontal tissues.

Summary Tumour necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK), a member of the TNF family, is a multi-functional cytokine that regulates cellular proliferation, angiogenesis, inflammation and apoptosis. In this study, we investigated TWEAK expression in periodontally diseased tissues and the effect of TWEAK on human gingival fibroblasts (HGF). Reverse transcription–polymerase chain reaction (RT–PCR) analysis and immunohistochemistry revealed that TWEAK and the TWEAK receptor, fibroblast growth factor-inducible 14 (Fn14), mRNA and protein were expressed in periodontally diseased tissues. HGF expressed Fn14 and produced interleukin (IL)-8 and vascular endothelial growth factor (VEGF) production upon TWEAK stimulation in a dose-dependent manner. The IL-8 and VEGF production induced by TWEAK was augmented synergistically by simultaneous stimulation with transforming growth factor (TGF)-β1 or IL-1β. IL-1β and TGF-β1 enhanced Fn14 expression in a dose-dependent manner. Moreover, TWEAK induced intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression on HGF in a dose-dependent manner. The ICAM-1 expression induced by TWEAK was augmented by TGF-β1. On the other hand, the TWEAK-induced VCAM-1 expression was inhibited by TGF-β1. Phosphatidylinositol 3-kinase (PI3K) and nuclear factor-kappaB (NF-κB) inhibitor inhibit both ICAM-1 and VCAM-1 expression induced by TWEAK. However, mitogen-activated protein kinase (MEK) and c-Jun NH2-terminal kinase (JNK) inhibitor enhanced only VCAM-1 expression on HGF. These results suggest that TWEAK may be involved in the pathophysiology of periodontal disease. Moreover, in combination with IL-1β or TGF-β1, TWEAK may be related to the exacerbation of periodontal disease to induce proinflammatory cytokines and adherent molecules by HGF.

The expression of intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1) on human gingival fibroblasts (HGF) may be important for migration and retention of inflammatory cells in periodontally diseased tissue. This study aimed to assess which cytokines regulate ICAM-1 and VCAM-1 expression on HGF. Tumour necrosis factor (TNF)-α and interferon (IFN)-γ enhanced both ICAM-1 and VCAM-1 expression on HGF. Interleukin (IL)-1β mainly up-regulated ICAM-1 expression. On the other hand, IL-4 and IL-13 enhanced only VCAM-1 expression on HGF. IL-10 did not modulate both ICAM-1 and VCAM-1 expression. Transforming growth factor (TGF)-β1 enhanced ICAM-1 expression. However, TGF-β1 inhibited the VCAM-1 expression induced by TNF-α or IL-4. Both ICAM-1 and VCAM-1 expression by HGF was inhibited by nuclear factor-kappaB (NF-κB) activation inhibitor (MG-132). Mitogen-activated protein kinases (MAPK) inhibitors did not influence ICAM-1 expression induced by TNF-α. Interestingly, VCAM-1 expression was enhanced by MEK inhibitor (PD98059) and c-Jun NH2-terminal kinase (JNK) inhibitor (SP600125). These results mean that the balance of cytokines in periodontally diseased tissue may be essential for control of ICAM-1 and VCAM-1 expression on HGF, and the balance of ICAM-1 and VCAM-1 expression might be important for regulation of leucocytes infiltration and retention in periodontally diseased tissue.

Summary We have demonstrated recently that CCL20 was expressed in periodontal diseased tissues and abundant CCR6 positive T cells infiltrated in periodontally diseased tissue. However, it is uncertain which cells can elicit CCL20 production. In the present study, we examined the properties of CCL20 production by human gingival fibroblasts (HGF) culture. Here, we report that interleukin-1 beta (IL-1β), tumour necrosis factor-alpha (TNF-α) and Escherichia coli lipopolysaccharide (LPS) can significantly induce the production of CCL20 by HGF. We found that TNF-α and E. coli LPS enhanced the production of CCL20 by HGF treated with IL-1β. In contrast, interferon-gamma (IFN-γ) dramatically diminished CCL20 production induced by IL-1β. Moreover, we demonstrated that nuclear factor-kappaB (NF-κB), p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinases (ERK) play an important role in mediating the production of CCL20 induced by IL-1β and TNF-α. On the other hand, we found that not only NF-κB, p38 MAPK and ERK but also c-Jun NH2-terminal kinase (JNK) are involved in CCL20 production induced by E. coli LPS. Finally, we found that HGF express CCR6, CCL20 receptor, and CCL20 induced vascular endothelial growth factor (VEGF) by HGF. Taken together, these findings that HGF will be a source of CCL20 in periodontal tissue, and the CCL20 production will be controlled by proinflammatory cytokine and bacterial LPS in periodontally diseased tissue. Thus, CCL20 by HGF might be involved in inflammatory cells infiltration, and promote the progression of periodontal disease.

Background/Aims: Genipin, the aglycon of geniposide found in gardenia fruit has long been considered for treatment of various diseases in traditional oriental medicine. Genipin has been used as a blue colorant in food industry. Genipin has recently been reported to have some pharmacological functions, such as antimicrobial, antitumor, and anti-inflammatory effects. The aim of this study was to examine whether genipin could modify CCL20 and IL-6, which are related to bone resorption in periodontal disease, expression in human periodontal ligament cells (HPDLCs). Methods: CCL20 and IL-6 productions from HPDLCs were determined by ELISA. Western blot analysis was used for the detection of signal transduction molecules expressions in HPDLCs. Results: Genipin prevented IL-1ß-mediated CCL20 and IL-6 production in HPDLCs. Moreover, genipin could suppress nuclear factor kappa B (NF-κB) p65, extracellular signalregulated kinase (ERK) and MAPK/ERK kinase (MEK) phosphorylations in IL-1ß-stimulated HPDLCs. NF-κB inhibitor and ERK inhibitor significantly inhibited IL-6 and CCL20 productions from IL-1ß-stimulated HPDLCs. Conclusions: These data provide a novel mechanism through which genipin could be used to provide direct benefits in periodontal disease to inhibit IL-6 and CCL20 productions in periodontal lesions.

CC chemokine ligand 20 (CCL20) plays a central role in the recruitment of CCR6-expressing cells, including Th17 cells which are related to bone resorption in periodontal lesions and thus in the development of periodontal disease. IL-6 is an important cytokine that is associated with the pathogenesis of periodontitis. However, the effect of IL-6 on CCL20 production is uncertain. The aim of this study was to examine whether IL-6 could modify CCL20 expression in human periodontal ligament cells (HPDLCs). HPDLCs expressed gp130 but did not express IL-6R on the surface of HPDLCs. So, IL-6 trans-signaling is important to recognize IL-6 by HPDLCs. IL-6/sIL-6R stimulation enhanced CCL20 production in IL-1β-stimulated HPDLCs. IL-6 produced from IL-1β-stimulated HPDLCs with sIL-6R could increase CCL20 production in HPDLCs with sIL-6R. Signal transducer and activator of transcription (STAT)3 activation was related to CCL20 production in IL-1β and IL-6/sIL-6R-stimulated HPDLCs. Our data suggests that HPDLCs, in response to IL-6, sIL-6R, and IL-1β, may shift chemokine production to that favoring CCR6-expressing cells recruitment in periodontal lesions.

We immunohistologically examined the cell densities and distribution of T and B cells in periodontitis and analyzed their relationship in terms of periodontal tissue destruction. Specimens were labeled with monoclonal antibodies for T cells (CD3) and B cells (CD20) and developed using the double staining technique. CD3+ cells appeared in low density infiltrates and increased gradually with the number of total infiltrates; in contrast, CD20+ cells did not appear in small infiltrates but increased rapidly with the number of infiltrates. The number of fibroblastic cells negatively correlated with that of the total infiltrates and CD20+ cells, but it did not correlate with the number of CD3+ cells. These findings suggest that the T cells infiltrated into the inflamed sites at the onset and increased gradually with the development of inflammation and that B cells infiltrated later than T cells and their number increased rapidly with inflammation.

CC chemokine ligand 20 (CCL20) is related to T-helper (Th)-17 cell migration, and Th17 cells play important roles in exacerbation in periodontal disease. However, the effect of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) on CCL20 production is unknown. In this study, we examined the mechanisms of TWEAK in combination with interleukin (IL)-1β-induced CCL20 production in human gingival fibroblasts (HGFs). TWEAK alone did not induce CCL20 production in HGFs. However, TWEAK enhanced CCL20 expression from IL-1β-stimulated HGFs in a dose-dependent manner. Inhibitors of p38 mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK), protein kinase B (Akt), and nuclear factor κB (NF-κB) significantly inhibited CCL20 production in TWEAK and IL-1β-stimulated HGFs. Western blot analysis revealed that phosphorylations of ERK, Akt, and inhibitor of NF-κB were enhanced in TWEAK and IL-1β-treated HGFs. These data suggest that TWEAK is positively related to Th17 cell migration in periodontally diseased tissues to enhance CCL20 production in IL-1β-stimulated HGFs.

CC chemokine ligand 20 (CCL20) plays a pivotal role in the recruitment of T-helper (Th)-17 cells and thus in the development of periodontal disease, but the effect of simultaneous interleukin (IL)-17A and IL-1β stimulation on CCL20 production in human gingival fibroblasts (HGFs) are not known. In this study, we investigated the mechanisms of IL-1β- and IL-17A-induced CCL20 production in HGFs. IL-17A synergistically enhanced CCL20 production from IL-1β-stimulated HGFs in a concentration-dependent manner. Extracellular signal-regulated kinase (ERK) and inhibitor of nuclear factor (NF)-κB-α phosphorylation were increased in IL-1β- and IL-17A-stimulated HGFs. Inhibitors of or ERK and NF-κB decreased IL-1β- and IL-17A-induced CCL20 production. IL-1β stimulation elevated IL-17 receptor C expression on HGFs. These data suggest that IL-1β is actively related to Th17 cell migration into peripheral tissues to induce production of the Th17 chemokine, CCL20. Therefore, IL-1β might be a therapeutic target for Th17-related diseases, such as periodontal disease and arthritis.

Periodontitis is a chronic bacterial infection of tooth-supporting structures. T-helper type 1 (Th1) cells are related to the exacerbation of periodontal disease. Human gingival fibroblasts (HGFs), the major cell type in periodontal connective tissues, are involved in immunological response in periodontal tissues. However, it is uncertain whether HGFs are related to Th1 response. Chemokine (C-X-C motif) ligand 10 (CXCL10) is a cytokine, that is related to Th1 cells migration. Intercellular adhesion molecule (ICAM)-1 is involved in Th1 cells retention and activation in inflamed tissue. The aim of this study is to examine the effect of oncostatin M (OSM) on CXCL10 and ICAM-1 expression in HGFs. OSM stimulation induced CXCL10 and ICAM-1 expression in HGFs. Moreover, the synergistic effects of CXCL10 release and ICAM-1 expression in HGFs were observed with combined stimulation of interleukin (IL)-1beta and OSM. OSM increased type 1 IL-1 receptor (IL-1R1) expression, and IL-1beta enhanced OSMRbeta expression on HGFs. IL-1beta + OSM stimulation enhanced the phosphorylation of inhibitor of nuclear factor kappaB (IkappaB)-alpha, signal transducer and activator of transcription (STAT)3, c-Jun N terminal kinase (JNK), and protein kinase B (Akt) compared to OSM or IL-1beta stimulation. CXCL10 production from OSM + IL-1beta stimulated HGFs was suppressed by nuclear factor (NF)-kappaB, STAT3, JNK, and phosphoinositide-3-kinase (PI3K) inhibitors. On the other hand, only NF-kappaB and STAT3 inhibitors suppressed ICAM-1 expression enhanced by OSM + IL-1beta treatment. These effects of OSM and IL-1beta may promote Th1 cells infiltration and retention in periodontally diseased tissues and be related to exacerbation of periodontal disease.

IL-6 is well recognized to be a potent bone resorptive agent and thus in the development of periodontal disease. Epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), the major catechins in green tea, and theaflavin-3,3'-digallate (TFDG), polyphenol in black tea, have multiple beneficial effects, but the effects of catechins and theaflavins on IL-6 production in human gingival fibroblasts (HGFs) are not known. In this study, we investigated the mechanisms by which EGCG, ECG, and TFDG inhibit tumor necrosis factor superfamily 14 (TNFSF14)-induced IL-6 production in HGFs. We detected TNFSF14 mRNA expression in human diseased periodontal tissues. TNFSF14 increased IL-6 production in HGFs in a concentration-dependent manner. EGCG, ECG, and TFDG prevented TNFSF14-mediated IL-6 production in HGFs. EGCG, ECG, and TFDG prevented TNFSF14-induced extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and nuclear factor-kappaB activation in HGFs. Inhibitors of ERK, JNK, and nuclear factor-kappaB decreased TNFSF14-induced IL-6 production. In addition, EGCG, ECG, and TFDG attenuated TNFSF14 receptor expression on HGFs. These data provide a novel mechanism through which the green tea and black tea polyphenols could be used to provide direct benefits in periodontal disease.

CC chemokine ligand 20 (CCL20) plays a pivotal role in the recruitment of Th17 cells and thus in the development of periodontal disease. Epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), the major catechins in green tea, have multiple beneficial effects, but the effects of catechins on CCL20 production in human gingival fibroblasts (HGFs) are not known. In this study, we investigated the mechanisms by which EGCG and ECG inhibit interleukin (IL)-17A-induced CCL20 production in human gingival fibroblasts. IL-17A increased CCL20 production in HGFs in a concentration-dependent manner. EGCG and ECG prevented IL-17A-mediated CCL20 production in HGFs. Inhibitors of p38 mitogen-activated protein kinase (MAPK) or extracellular signal-regulated kinase (ERK) decreased IL-17A-induced CCL20 production. EGCG and ECG prevented IL-17A-induced phosphorylation of p38 MAPK and ERK in HGFs. In addition, EGCG and ECG attenuated IL-17 receptor expression on HGFs. These data provide a novel mechanism through which the green tea flavonoids catechins could be used to provide direct benefits in periodontal disease.

BACKGROUND AND OBJECTIVE CXC chemokine 10 (CXCL10) activates CXC chemokine receptor 3 (CXCR3) and attracts activated T-helper 1 cells. In this study we examined the effects of cytokines on CXCL10 production by human gingival fibroblasts. MATERIAL AND METHODS Human gingival fibroblasts were exposed to pro-inflammatory cytokines (interleukin-1beta, tumor necrosis factor-alpha), a T-helper 1 cytokine (interferon-gamma), T-helper 2 cytokines (interleukin-4, interleukin-13), T-helper 17 cytokines (interleukin-17A, interleukin-22) and regulatory T-cell cytokines (interleukin-10, transforming growth factor-beta1) for 24 h. CXCL10 production by human gingival fibroblasts was examined by enzyme-linked immunosorbent assay. RESULTS Human gingival fibroblasts produced CXCL10 protein upon stimulation with interleukin-1beta, tumor necrosis factor-alpha and interferon-gamma. Treatment of human gingival fibroblasts with interferon-gamma in combination with tumor necrosis factor-alpha or interleukin-1beta resulted in a synergistic production of CXCL10. However, interleukin-4 and interleukin-13 inhibited CXCL10 production by interferon-gamma-stimulated or tumor necrosis factor-alpha-stimulated-human gingival fibroblasts. On the other hand, interleukin-17A and interleukin-22 enhanced CXCL10 production by human gingival fibroblasts treated with interferon-gamma and inhibited CXCL10 production by tumor necrosis factor-alpha-stimulated human gingival fibroblasts. Furthermore, the anti-inflammatory cytokine, interleukin-10, inhibited CXCL10 production by both interferon-gamma- and tumor necrosis factor-alpha-stimulated human gingival fibroblasts, but transforming growth factor-beta1 enhanced interferon-gamma-mediated CXCL10 production by human gingival fibroblasts. CONCLUSION These results mean that the balance of cytokines in periodontally diseased tissue may be essential for the control of CXCL10 production by human gingival fibroblasts, and the production of CXCL10 might be important for the regulation of T-helper 1 cell infiltration in periodontally diseased tissue.

Summary CXCL12 is a CXC chemokine that is related to lymphocyte infiltration and angiogenesis in inflammatory sites such as arthritis. However, the expression and roles of CXCL12 in periodontal disease are uncertain. The aim of this study was to assess the expression of CXCL12 and its receptor, CXCR4, in periodontal tissue and to investigate the properties of CXCL12 and CXCR4 expression by human gingival fibroblasts (HGF). RT-PCR analysis revealed that CXCL12 and CXCR4 mRNA were expressed in both normal gingival tissues and periodontal diseased tissues. Immunohistochemistry disclosed that CXCL12 was expressed and CXCR4 positive cells were found in both normal and periodontal diseased gingival tissues. Our in vitro experiments elucidated that HGF constitutively produced CXCL12, and the levels were enhanced by stimulation with tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ), transforming growth factor-β (TGF–β), regulated upon activation normal T cell expressed and secreted (RANTES) and macrophage inflammatory protein 3α (MIP-3α). On the other hand, heat killed Porphyromonas gingivalis (P. gingivalis) and P. gingivalis LPS reduced the CXCL12 production by HGF. Flow cytometry analysis clarified that CXCR4 was highly expressed on HGF, and CXCR4 expression was abrogated by TNF-α, IFN-γ and P. gingivalis LPS. Moreover, CXCL12 induced vascular endothelial growth factor (VEGF) production by HGF. Our results demonstrated that CXCL12 might be related to CXCR4+ cells infiltration and angiogenesis both in normal periodontal tissues and periodontal diseased tissue. P. gingivalis, a known periodontal pathogen, inhibits the production of CXCL12 and the expression of CXCR4 by HGF. This fact means that P. gingivalis may inhibit CXCR4+ cells infiltration and neovascularization in periodontal tissue and escape from the immune response.

Transmission electron microscopy (TEM) and x-ray microanalysis (XMA) were used for the study of the ultrastructure of the lumens of dentinal tubules in superficial layers of dentin specimens obtained by use of a new biopsy technique from both hypersensitive and naturally desensitized areas of exposed root surfaces, in vivo. The TEM images showed clearly that the lumens of most of the tubules were occluded with mineral crystals in naturally desensitized areas, but such lumens were empty and surrounded with peritubular and intertubular dentin in hypersensitive areas. Moreover, electron-dense structures that lined peritubular dentin were observed in the empty lumens of dentinal tubules.