IL-1beta regulates cellular proliferation, prostaglandin E2 synthesis, plasminogen activator activity, osteocalcin production, and bone resorptive activity of the mouse calvarial bone cells

B. abortus Infection Promotes an Imbalance in the Adipocyte–Osteoblast Crosstalk Favoring Bone Resorption

Osteoarticular injury is the most common presentation of active brucellosis in humans. Osteoblasts and adipocytes originate from mesenchymal stem cells (MSC). Since those osteoblasts are bone-forming cells, the predilection of MSC to differentiate into adipocytes or osteoblasts is a potential factor involved in bone loss. In addition, osteoblasts and adipocytes can be converted into each other according to the surrounding microenvironment. Here, we study the incumbency of B. abortus infection in the crosstalk between adipocytes and osteoblasts during differentiation from its precursors. Our results indicate that soluble mediators present in culture supernatants from B. abotus-infected adipocytes inhibit osteoblast mineral matrix deposition in a mechanism dependent on the presence of IL-6 with the concomitant reduction of Runt-related transcription factor 2 (RUNX-2) transcription, but without altering organic matrix deposition and inducing nuclear receptor activator ligand kβ (RANKL) expression. Secondly, B. abortus-infected osteoblasts stimulate adipocyte differentiation with the induction of peroxisome proliferator-activated receptor γ (PPAR-γ) and CCAAT enhancer binding protein β (C/EBP-β). We conclude that adipocyte–osteoblast crosstalk during B. abortus infection could modulate mutual differentiation from its precursor cells, contributing to bone resorption.

The Effects of Lentivirus-Mediated Gene Silencing of RARβ on the Stemness Capability of Non-Small Cell Lung Cancer

Retinoic acid receptor beta is a nuclear receptor protein that binds to retinoic acid (RA) to mediate cellular signalling in embryogenic morphogenesis, cell growth, and differentiation. However, the function of RARβ in cancer stem cells (CSCs) has yet to be determined. This study aimed to understand the role of RARβ in regulating cell growth and differentiation of lung cancer stem cells. Based on the clonogenic assay, spheroid assay, mRNA levels of stem cell transcription factors, and cell cycle being arrested at the G0/G1 phase, the suppression of RARβ resulted in significant inhibition of A549 parental cell growth. This finding was contradictory to the results seen in CSCs, where RARβ inhibition enhanced the cell growth of putative and non-putative CSCs. These results suggest that RARβ suppression may act as an essential regulator in A549 parental cells, but not in the CSCs population. The findings in this study demonstrated that the loss of RARβ promotes tumorigenicity in CSCs. Microarray analysis revealed that various cancer pathways were significantly activated following the suppression of RARβ. The changes seen might compensate for the loss of RARβ function, CSCs population's aggressiveness, which led to the CSCs population's aggressiveness. Thus, understanding the role of RARβ in regulating the stemness of CSCs may lead to targeted therapy for lung CSCs.

Interaction of Brucella abortus with Osteoclasts: a Step toward Understanding Osteoarticular Brucellosis and Vaccine Safety

Osteoarticular disease is a frequent complication of human brucellosis. Vaccination remains a critical component of brucellosis control, but there are currently no vaccines for use in humans, and no in vitro models for assessing the safety of candidate vaccines in reference to the development of bone lesions currently exist. While the effect of Brucella infection on osteoblasts has been extensively evaluated, little is known about the consequences of osteoclast infection. Murine bone marrow-derived macrophages were derived into mature osteoclasts and infected with B. abortus 2308, the vaccine strain S19, and attenuated mutants S19vjbR and B. abortus ΔvirB2 While B. abortus 2308 and S19 replicated inside mature osteoclasts, the attenuated mutants were progressively killed, behavior that mimics infection kinetics in macrophages. Interestingly, B. abortus 2308 impaired the growth of osteoclasts without reducing resorptive activity, while osteoclasts infected with B. abortus S19 and S19vjbR were significantly larger and exhibited enhanced resorption. None of the Brucella strains induced apoptosis or stimulated nitric oxide or lactose dehydrogenase production in mature osteoclasts. Finally, infection of macrophages or osteoclast precursors with B. abortus 2308 resulted in generation of smaller osteoclasts with decreased resorptive activity. Overall, Brucella exhibits similar growth characteristics in mature osteoclasts compared to the primary target cell, the macrophage, but is able to impair the maturation and alter the resorptive capacity of these cells. These results suggest that osteoclasts play an important role in osteoarticular brucellosis and could serve as a useful in vitro model for both analyzing host-pathogen interactions and assessing vaccine safety.

MicroRNA-125a-3p participates in odontoblastic differentiation of dental pulp stem cells by targeting Fyn

Fyn is a member of the protein tyrosine kinase family and its overexpression is associated with various types of inflammation. MicroRNAs can regulate the expression of target genes and play an important role in varied physiological and pathological processes. Based on the important role of Fyn and microRNA-125a-3p (miR-125a-3p) in inflammation, and combined with the bioinformatics studies, we performed in this study and chose miR-125a-3p as the focus of our research. During the progression of inflammation, we found that the expression of miR-125a-3p was decreased while the expression of Fyn was up-regulated. Fyn formed a complex with Neuropilin-1, which inhibited odontoblastic differentiation and expanded inflammatory responses through nuclear factor-κB signal pathways in dental pulp stem cells (DPSCs). These findings suggested that miR-125a-3p plays an important role in odontoblastic differentiation of DPSCs by targeting Fyn, implying its therapeutic potential in dental caries.

Enamel matrix derivative stabilizes blood clot and improves clinical healing in deep pockets after flapless periodontal therapy: A Randomized Clinical Trial

AIM

An acute phase response is induced after non-surgical periodontal treatment (SRP). The main aim of this study was to compare acute phase (24-hr) and medium-term (3-months) inflammation and clinical outcomes after SRP with or without application of enamel matrix derivative (EMD) in sites with probing pocket depth (PPD) ≥ 6 mm.

METHODS

Thirty-eight periodontitis-affected subjects were randomized to SRP or SRP + EMD. Periodontal parameters were recorded at baseline and 3 months. Serum samples were collected at baseline, 1 and 90 days after treatment.

RESULTS

Both treatments triggered an intense acute inflammation on day 1, which regressed to baseline values at 3 months. D-dimer and cystatin C levels did not show sharp increases in SRP + EMD group 24 hr after treatment, compared to SRP. Significant difference between groups was observed for D-dimer (p < 0.001). EMD application was also associated with better periodontal healing as shown by greater PPD reduction and clinical attachment level gain in sites with PPD ≥ 6 mm, and higher number of cases with no residual PPD ≥ 6 mm (p < 0.05) at 3 months.

CONCLUSIONS

EMD application after non-SRP resulted in lower fibrinolysis, and better periodontal healing of deep pockets. These initial observations warrant further investigations on the potential to modulate both local and systemic outcomes of non-SRP. NCT03544931.

The Role of Neuropilin-1-FYN Interaction in Odontoblast Differentiation of Dental Pulp Stem Cells

Abnormal odontoblast differentiation of dental pulp stem cells (DPSCs) caused by inflammation is closely related to the development of dental caries. Neuropilin-1 (NRP1) is one of the members of neuropilin family. It can combine with disparate ligands involved in regulating cell differentiation. FYN belongs to the protein-tyrosine kinase family, which has been implicated in the control of cell growth, and the effect can be further strengthened by inflammatory factors. In our studies, we verified that NRP1 can form complexes with FYN and have the correlation changes in odontoblast differentiation of DPSCs. Therefore, we surmise that in the progress of dental caries, NRP1 interacts with FYN, by expanding inflammation and inhibition of odontoblast differentiation of DPSCs through nuclear factor kappa B (NF-κB) signaling pathway. In this subject, we first investigated the expression and interaction of NRP1 and FYN in DPSCs. And then, we researched the effect of this complex controlling downstream signal pathway in normal or inflammation stimulated DPSCs. Finally, we analyzed the relationship between this role and odontoblast differentiation of DPSCs. This research will provide the molecular mechanism of inflammation factors of dental caries through activating NF-κB signal regulating odontoblast differentiation in DPSCs for finding new potential drug targets for the clinical treatment of dental caries.

CXCL8 and CCL20 Enhance Osteoclastogenesis via Modulation of Cytokine Production by Human Primary Osteoblasts

Generalized osteoporosis is common in patients with inflammatory diseases, possibly because of circulating inflammatory factors that affect osteoblast and osteoclast formation and activity. Serum levels of the inflammatory factors CXCL8 and CCL20 are elevated in rheumatoid arthritis, but whether these factors affect bone metabolism is unknown. We hypothesized that CXCL8 and CCL20 decrease osteoblast proliferation and differentiation, and enhance osteoblast-mediated osteoclast formation and activity. Human primary osteoblasts were cultured with or without CXCL8 (2–200 pg/ml) or CCL20 (5–500 pg/ml) for 14 days. Osteoblast proliferation and gene expression of matrix proteins and cytokines were analyzed. Osteoclast precursors were cultured with CXCL8 (200 pg/ml) and CCL20 (500 pg/ml), or with conditioned medium (CM) from CXCL8 and CCL20-treated osteoblasts with or without IL-6 inhibitor. After 3 weeks osteoclast formation and activity were determined. CXCL8 (200 pg/ml) and CCL20 (500 pg/ml) enhanced mRNA expression of KI67 (2.5–2.7-fold), ALP (1.6–1.7-fold), and IL-6 protein production (1.3–1.6-fold) by osteoblasts. CXCL8-CM enhanced the number of osteoclasts with 3–5 nuclei (1.7-fold), and with >5 nuclei (3-fold). CCL20-CM enhanced the number of osteoclasts with 3–5 nuclei (1.3-fold), and with >5 nuclei (2.8-fold). IL-6 inhibition reduced the stimulatory effect of CXCL8-CM and CCL20-CM on formation of osteoclasts. In conclusion, CXCL8 and CCL20 did not decrease osteoblast proliferation or gene expression of matrix proteins. CXCL8 and CCL20 did not directly affect osteoclastogenesis. However, CXCL8 and CCL20 enhanced osteoblast-mediated osteoclastogenesis, partly via IL-6 production, suggesting that CXCL8 and CCL20 may contribute to osteoporosis in rheumatoid arthritis by affecting bone cell communication.

Brucella abortus invasion of osteoblasts inhibits bone formation

Osteoarticular brucellosis is the most common presentation of the active disease in humans. Loss of bone is a serious complication of localized bacterial infection of bones or the adjacent tissue, and brucellosis proved not to be the exception. The skeleton is a dynamic organ system which is constantly remodeled. Osteoblasts are responsible for the deposition of bone matrix and are thought to facilitate the calcification and mineralization of the bone matrix, and their function could be altered under infectious conditions. In this article, we describe immune mechanisms whereby Brucella abortus may invade and replicate within osteoblasts, inducing apoptosis, inhibiting mineral and organic matrix deposition, and inducing upregulation of RANKL expression. Additionally, all of these mechanisms contributed in different ways to bone loss. These processes implicate the activation of signaling pathways (mitogen-activated protein kinases [MAPK] and caspases) involved in cytokine secretion, expression of activating molecules, and cell death of osteoblasts. In addition, considering the relevance of macrophages in intracellular Brucella survival and proinflammatory cytokine secretion in response to infection, we also investigated the role of these cells as modulators of osteoblast survival, differentiation, and function. We demonstrated that supernatants from B. abortus-infected macrophages may also mediate osteoblast apoptosis and inhibit osteoblast function in a process that is dependent on the presence of tumor necrosis factor alpha (TNF-α). These results indicate that B. abortus may directly and indirectly harm osteoblast function, contributing to the bone and joint destruction observed in patients with osteoarticular complications of brucellosis.

Heme oxygenase-1 mediates protective effects on inflammatory, catabolic and senescence responses induced by interleukin-1β in osteoarthritic osteoblasts

Osteoarthritis (OA) is a chronic degenerative joint disease showing altered bone metabolism. Osteoblasts contribute to the regulation of cartilage metabolism and bone remodeling. We have shown previously that induction of heme oxygenase-1 (HO-1) protects OA cartilage against inflammatory and degradative responses. In this study, we investigated the effects of HO-1 induction on OA osteoblast metabolism. HO-1 was induced with cobalt protoporphyrin IX (CoPP) and by transduction with LV-HO-1. In osteoblasts stimulated with interleukin (IL)-1β, CoPP enhanced mineralization, the expression of a number of markers of osteoblast differentiation such as Runx2, bone morphogenetic protein-2, osteocalcin, and collagen 1A1 and 1A2, as well as the ratio osteoprotegerin/receptor activator of nuclear factor-κB ligand. HO-1 induction significantly reduced the expression of matrix metalloproteinase (MMP)-1, MMP-2 and MMP-3, and the production of pro-inflammatory cytokines such as tumor necrosis factor-α and IL-6 whereas IL-10 levels increased. HO-1 also exerted inhibitory effects on prostaglandin (PG)E(2) production which could be dependent on cyclooxygenase-2 and microsomal PGE synthase-1 down-regulation. The activity of senescence-associated β-galactosidase and the expression of the senescence marker caveolin-1 were significantly decreased after HO-1 induction. The inhibition of nuclear factor-κB activation induced by IL-1β in OA osteoblasts may contribute to some HO-1 effects. Our results have shown that HO-1 decreases the production of relevant inflammatory and catabolic mediators that participate in OA pathophysiology thus eliciting protective effects in OA osteoblasts.

Telomerase-deficient mice exhibit bone loss owing to defects in osteoblasts and increased osteoclastogenesis by inflammatory microenvironment

Telomere shortening owing to telomerase deficiency leads to accelerated senescence of human skeletal (mesenchymal) stem cells (MSCs) in vitro, whereas overexpression leads to telomere elongation, extended life span, and enhanced bone formation. To study the role of telomere shortening in vivo, we studied the phenotype of telomerase-deficient mice (Terc(-/-)). Terc(-/-) mice exhibited accelerated age-related bone loss starting at 3 months of age and during 12 months of follow-up revealed by dual-energy X-ray absorptiometric (DXA) scanning and by micro-computed tomography (µCT). Bone histomorphometry revealed decreased mineralized surface and bone-formation rate as well as increased osteoclast number and size in Terc(-/-) mice. Also, serum total deoxypyridinoline (tDPD) was increased in Terc(-/-) mice. MSCs and osteoprogenitors isolated from Terc(-/-) mice exhibited intrinsic defects with reduced proliferating cell number and impaired osteogenic differentiation capacity. In addition, the Terc(-/-) -MSC cultures accumulated a larger proportion of senescent β-galactosidase(+) cells and cells exhibiting DNA damage. Microarray analysis of Terc(-/-) bone revealed significant overexpression of a large number of proinflammatory genes involved in osteoclast (OC) differentiation. Consistently, serum obtained from Terc(-/-) mice enhanced OC formation of wild-type bone marrow cultures. Our data demonstrate two mechanisms for age-related bone loss caused by telomerase deficiency: intrinsic osteoblastic defects and creation of a proinflammatory osteoclast-activating microenvironment. Thus telomerization of MSCs may provide a novel approach for abolishing age-related bone loss.

Osteoblast physiology in normal and pathological conditions

Osteoblasts are mononucleated cells that are derived from mesenchymal stem cells and that are responsible for the synthesis and mineralization of bone during initial bone formation and later bone remodelling. Osteoblasts also have a role in the regulation of osteoclast activity through the receptor activator of nuclear factor κ-B ligand and osteoprotegerin. Abnormalities in osteoblast differentiation and activity occur in some common human diseases such as osteoporosis and osteoarthritis. Recent studies also suggest that osteoblast functions are compromised at sites of focal bone erosion in rheumatoid arthritis.

Combinatory responses of proinflamamtory cytokines on nitric oxide-mediated function in mouse calvarial osteoblasts

Combinatory responses of proinflamamtory cytokines have been examined on the nitric oxide-mediated function in cultured mouse calvarial osteoblasts. Interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) induced iNOS gene expression and NO production, although these actions were inhibited by L-NG-monomethylarginine (L-NMMA) and decreased alkaline phosphatase (ALPase) activity. Furthermore, NO donors, sodium nitroprusside (SNP) and NONOate dose-dependently elevated ALPase activity. In contrast, transforming-growth factor-beta (TGF-beta) decreased NO production stimulated by IL-1beta, TNF-alpha and interferon-gamma (IFN-gamma). iNOS was expressed by mouse calvarial osteoblast cells after stimulation with IL-1beta, TNF-alpha, and IFN-gamma. Incubation of mouse calvarial osteoblast cells with the cytokines inhibited growth and ALPase activity. However, TGF-beta-treatment abolished these effects of IL-1beta, TNF-alpha and IFN-gamma on growth inhibition and stimulation of ALPase in mouse calvarial osteoblast cells. In contrast, IL-1beta, TNF-alpha, and IFN-gamma exerted growth-inhibiting effects on mouse calvarial osteoblast cells which were partly NO-dependent. The results suggest that NO may act predominantly as a modulator of cytokine-induced effects on mouse calvarial osteoblast cells and TGF-beta is a negative regulator of the NO production stimulated by IL-1beta, TNF-alpha and IFN-gamma.

Effect of safflower seeds supplementation on stimulation of the proliferation, differentiation and mineralization of osteoblastic MC3T3-E1 cells

Anti-bone resorption properties of the Korean herbal formulation, Gami-Honghwain (HJ), which comprises Carthamus tinctorius L. seed and hominis placenta, were investigated. We demonstrate that the production of PGE2 is inhibited by 20-100 microg/ml HJ in nontransformed osteoblastic cells (MC3T3-E1 cells), indicating that HJ inhibits PGE2 production. The effect of HJ on the proliferation and osteoblastic differentiation in MC3T3-E1 was also studied. HJ dose-dependently increased DNA synthesis (significant at 20-100 microg/ml), and increased alkaline phosphatase (ALP) and prolyl hydroxylase activities of MC3T3-E1 cells (20-100 microg/ml), while anti-estrogen tamoxifen eliminated the stimulation of proliferation and ALP activity of MC3T3-E1 which was induced by HJ. These results indicate that HJ directly stimulates cell proliferation and differentiation of osteoblasts. Also, when we assessed the effects of HJ on osteoblastic differentiation in MC3T3-E1, HJ enhanced ALP activity and mineralization in a dose- and time-dependent fashion. This stimulatory effect of the HJ was observed at relatively low doses (significant at 20-100 microg/ml and maximal at 100 microg/ml). Northern blot analysis showed that the HJ (60 microg/ml) increased in bone morphogenetic protein-2 as well as ALP mRNA concentrations in MC3T3-E1 cells. HJ (100 microg/ml) slightly increased in type I collagen mRNA abundance throughout the culture period, whereas it markedly inhibited the gene expression of collagenase-1 between days 15 and 20 of culture. These results indicate that HJ has anabolic effect on bone through the promotion of osteoblastic differentiation, suggesting that it could be used for the treatment of common metabolic bone diseases.

Hypoxia and Reoxygenation Augment Bone-Resorbing Factor Production From Human Periodontal Ligament Cells

BACKGROUND

Oxygen deficiency caused by occlusal trauma and smoking may be associated with bone resorption in periodontitis. In the present study, the effects of hypoxia and reoxygenation on the production of bone-resorbing factors by cultured human periodontal ligament (PDL) cells were examined.

METHODS

Human PDL cells were cultured in 1% O(2) (hypoxia), 20% O(2) (normal oxygen tension [normoxia]), or an oxygen concentration that went from 1% to 20% (reoxygenation). The concentrations of bone-resorbing factors, i.e., vascular endothelial growth factor (VEGF), interleukin (IL)-6 and -1beta, tumor necrosis factor-alpha (TNF-alpha), and prostaglandin E(2) (PGE(2)), in the cell culture supernatants were determined by enzyme-linked immunosorbent assay. Expression of the corresponding mRNAs was detected by reverse transcription-polymerase chain reaction.

RESULTS

Significantly higher extracellular concentrations of VEGF and IL-6 were detected along with greater corresponding mRNA expression in the hypoxia group compared to the normoxia group. The protein production and mRNA expression of IL-1beta were observed only in the hypoxia group. Neither TNF-alpha nor PGE(2) was detectable in samples from either group, whereas cyclooxygenase-2 mRNA was detected. However, PGE(2) was detected after reoxygenation. Furthermore, VEGF and IL-6 and -1beta production also tended to increase in extracellular concentration and mRNA level after reoxygenation.

CONCLUSION

Hypoxia and reoxygenation may stimulate the PDL to produce VEGF, IL-6 and -1beta, and PGE2, which could result in the resorption of alveolar bone in periodontitis.

Herbal formulation, Yukmi-jihang-tang-Jahage, regulates bone resorption by inhibition of phosphorylation mediated by tyrosine kinase Src and cyclooxygenase expression

Anti-bone resorption properties of the Korean herbal medicine, Yukmi-jihang-tang (YJ), which is comprised of seven herbs such as Rehmannia glutinosa Libosch, Dioscorea japonica THUNB, Cornus officinalis SIEB et. ZUCC, Smilax glabra ROXB, Paeonia suffruticosa ANDR, Alisma platago-aquatica var. orientale SAMUELS and Hominis placenta, were investigated. Cyclooxygenase-2 (COX-2) and tyrosine kinase involve on prostaglandin E2 (PGE2) production in mouse calvarial osteoblasts stimulated by cytokine interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) and/or interleukin-6 (IL-6). IL-1beta and IL-6 and to a lesser extent TNF-alpha, enhanced COX-2 mRNA levels in calvarial osteoblasts. TGF-beta, YJ (100microg/ml) and their combinations of YJ+TGF-beta reduced the COX-2 mRNA level, PGE2 biosynthesis and bone resorption induced by IL-1beta, TNF-alpha, IL-6 or their combination. Finally, YJ inhibits in vitro and in vivo bone resorption by inhibition of phosphorylation of peptide substrates. The parathyroid hormone-induced bone resorption in mouse fetal long bone cultures was inhibited with an IC(50) of 16microg/ml. YJ dose-dependently reduced the hypercalcemia induced in mice by IL-1beta and partly prevented bone loss and microarchitectural changes in young ovariectomized rats, showing that the protective effect on bone was exerted via the inhibition of bone resorption. These results indicate that the synergy between IL-beta, TNF-alpha, IL-6 on PGE2 production is due to an enhanced gene expression of COX-2 and that tyrosine kinase(s) are involved in the signal transduction of COX-2 in mouse calvarial osteoblasts. Thus, YJ as a possible Src family kinase inhibitor may be useful for the treatment of diseases associated with elevated bone loss. This result also suggested that the YJ extracts is effective for bone resorptive action in bone cells.

Dietary supplementation of omega-3 fatty acid and circulating levels of interleukin-1beta, osteocalcin, and C-reactive protein in rats

BACKGROUND

In this study, we evaluated the effects of two different regimes of dietary supplementation of omega-3 fatty acid on serum levels of interleukin-1 beta (IL-1beta), osteocalcin (OC), and C-reactive protein (CRP) in experimental periodontitis.

METHODS

Experimental periodontitis was induced by repeated injections of Escherichia coli lipopolysaccharide (LPS). Thirty-nine adult male Sprague-Dawley rats were divided into four study groups as follows: an LPS positive control group; a saline (negative) control group; and two different groups with omega-3 fatty acid dietary supplementation, one in which we gave the supplement subsequent to disease induction (TO3) and the other in which the agent was started prior to and continued subsequent to LPS injections (P + TO3). In the TO3 group, omega-3 fatty acid administration was performed for 14 days following induction of experimental periodontitis. In the P + TO3 group, omega-3 fatty acid was given for 14 days prior to the start of LPS injections and was continued for another 14 days subsequent to the induction of experimental periodontitis. On day 15 of the first LPS injection, serum samples were obtained and rats were sacrificed. Serum samples were analyzed for IL-1beta, OC, and CRP concentrations by enzyme-linked immunosorbent assay. Defleshed jaws were analyzed morphometrically for alveolar bone loss. Data were evaluated statistically by non-parametric tests.

RESULTS

LPS injection resulted in statistically significantly more bone loss compared to the saline control group (P <0.05). None of the omega-3 fatty acid administration groups showed evidence that this fatty acid was effective in preventing LPS-induced alveolar bone loss. TO3 and P + TO3 groups revealed significantly higher IL-1beta and OC levels than the LPS group (P <0.05). The study groups exhibited no significant differences in the serum CRP levels.

CONCLUSIONS

Omega-3 fatty acid administration does not seem to influence circulating levels of CRP. The significantly increased serum OC level observed in both omega-3 fatty acid regimes is curious and could have an effect on bone turnover, as could the further significant increase in serum IL-1beta, which could counteract any osteoblastic induction by OC through promotion of osteoclast activity. The lack of a therapeutic benefit of omega-3 fatty acid in this study, despite the effects on OC and IL-1beta, is difficult to explain, and further studies are required to more fully assess the potential role of this fatty acid in periodontal treatment.

Suppressive effects of a water extract of Ulmus davidiana Planch (Ulmaceae) on collagen-induced arthritis in mice

Ulmus davidiana Planch (Ulmaceae) has long been known to have anti-inflammatory and protective effects on damaged tissue, inflammation and bone resorption. Therefore, this study was undertaken to address (1) whether the water extract of the bark of Ulmus davidiana Planch (Ulmaceae) (UD) can modulate the expression of inducible inflammatory cytokines in mice; (2) in order to assess the therapeutic effects of UD in collagen-induced arthritis (CIA) in mice. DBA/1 mice were immunized with bovine type II collagen. After a second collagen immunization, mice were treated with UD orally at 100mg/kg once a day for 3 weeks. Paws were evaluated macroscopically for redness, swelling and deformities. The levels of TNF-alpha and IL-1beta in the ankle were examined. The severity of arthritis within the knee joints was evaluated by histological assessment of cartilage destruction and pannus formation. Administration of UD significantly suppressed the progression of CIA and inhibited the production of TNF-alpha and IL-1beta in the paws. The erosion of cartilage was dramatically reduced in mouse knees after treatment with UD. In the serum of UD-treated mice, the levels of IL-4 and IL-10, anti-inflammatory cytokines, were increased. From the results, it was concluded that administration of UD has therapeutic effects on CIA including protection of cartilage and RA for a potential therapy.

PGE2 induces the gene expression of bone matrix metalloproteinase-1 in mouse osteoblasts by cAMP-PKA signaling pathway

Prostaglandin E2 (PGE2), an abundant eicosanoid in bone, has been implicated in a number of pathological states associated with bone loss, and is also known to stimulate matrix metalloproteinase (MMP)-1 synthesis and secretion in rat and human osteoblast cells, although the nature of the intracellular reaction remains unclear. Although MMP-1 plays a critical role in bone-remodeling, it would be of interest to examine whether PGE2 regulates MMP-1 expression by mouse osteoblasts or not. Here we demonstrate that PGE2 is a potent inducer of MMP-1 production in fetal osteoblasts and show that PGE2 stimulates the activity of the MMP-1 promoter in osteoblasts, suggesting that PGE2 controls MMP-1 gene expression at least at the transcriptional level. PGE2 induced MMP-1 messenger RNA (mRNA) expression in the cells within 4 h, and this expression was maintained for 36 h. The increase in MMP-1 production with 0.1-2.0 microM PGE2 was dose-dependent. We also found that PGE2 (1.5 microM) up-regulated MMP-1 protein levels in cultured mouse osteoblasts, as evidenced by ELISA. To examine whether PGE2 mediated response and signal pathway are involved in the intracellular action, the PGE2-mediated expression of the MMP-1 gene was investigated in mouse osteoblast cells. A Northern blot analysis showed that PGE2 and PGE1 were potent stimulators of MMP-1 transcription, and the presence of thromboxane B2 had no effect. The increase in MMP-1 transcript after PGE2 treatment was observed at 4h, reaching a maximum at 6h, and persisted for 24h. This response was dose-dependent. Cycloheximide, an inhibitor of protein synthesis, completely blocked this effect by PGE2, indicating that the expression of other genes is also required. The second messenger analog, 8-bromo-cAMP, mimicked the effects of PGE2 by stimulating a dose-dependent increase in MMP-1 mRNA levels, with a maximal effect that was quantitatively similar to that observed with PGE2. Thus, the present results strongly suggest that the PGE2 stimulation of MMP-1 synthesis is due to the activation of MMP-1 gene transcription and a subsequent marked increase in MMP-1 transcription. This effect is dependent on de novo protein synthesis and is mimicked by protein kinase A activation. The findings suggest that PGE2 is involved in the cAMP-PKA signaling pathway in regulating MMP-1 gene expression in osteoblasts.

PGE2 induces IL-1beta gene expression in mouse osteoblasts through a cAMP-PKA signaling pathway

Prostaglandin E2 (PGE2), an abundant eicosanoid in bone, has been implicated in a number of pathological states associated with bone loss and is also known to stimulate matrix metalloproteinase-1 synthesis and secretion in rat and human osteoblast cells, although the intracellular reactions responsible for this remain unclear. Interleukin-1beta (IL-1beta) is a cytokine that plays a critical role in bone remodeling and appears to act as a downstream effector of most bone-resorbing agents. However, the issue of whether PGE2 regulates the expression of IL-1beta in mouse osteoblasts has not been resolved. In this work, we demonstrate that PGE2 is a potent inducer of IL-1beta production by fetal osteoblasts and show that PGE2 stimulates the activity of the IL-1beta promoter in osteoblasts, suggesting that PGE2 controls IL-1beta gene expression at least at the transcriptional level. PGE2 was found to induce IL-1beta mRNA expression in the cells within 4 h and the level of expression was maintained for 36 h. A dose-related increase in IL-1beta production was found with 0.1-2.0 microM PGE2. The induction of IL-1beta protein in the medium paralleled the induction of IL-1beta mRNA levels. The role of cAMP activation in PGE2-mediated IL-1beta production was examined by the effects of forskolin, an adenylyl cyclase (AC) activator and dideoxyadenosine (DDA), an AC inhibitor. Forskolin enhanced and DDA blocked the production of IL-1beta by PGE2. In addition, PGE2-mediated IL-1beta induction was completely inhibited by the cAMP antagonist, Rp-cAMP, and protein kinase A (PKA) inhibitors of KT5720 and H89. The PGE2-induced production of IL-1beta was also blocked by the PKA inhibitor PKI14-22. However, a specific inhibitor of protein kinase C, calphostin C, had no affect on PGE2-induced IL-1beta gene expression. Among the potential agonists, forskolin was a potent inducer of IL-1beta expression, while phorbol myristate acetate and serum had little effect. These findings indicate that PGE2 involves the cAMP-PKA signaling pathway in regulating IL-1beta gene expression in osteoblasts.

Effects of TGF-β, TNF-α, IL-β and IL-6 alone or in combination, and tyrosine kinase inhibitor on cyclooxygenase expression, prostaglandin E2 production and bone resorption in mouse calvarial bone cells

Cyclooxygenase-2 (COX-2) and tyrosine kinase, which are involved in the biosynthesis of prostaglandin E(2) (PGE(2)) in mouse calvarial osteoblasts, are stimulated by cytokine interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) and/or interleukin-6 (IL-6). IL-1beta and IL-6 and, to a lesser extent, TNF-alpha, enhances COX-2 mRNA levels in calvarial osteoblasts. Simultaneous treatment with IL-6 and IL-1beta and TNF-alpha resulted in enhanced COX-2 mRNA levels accompanied by the cooperative stimulation of PGE(2) biosynthesis compared to cells treated with IL-1beta or TNF-alpha or IL-6 alone. In contrast, the presence of TGF-beta reduced COX-2 mRNA level, PGE(2) biosynthesis and bone resorption induced by IL-1beta, TNF-alpha, IL-6 or a combination thereof. However, neither IL-1beta, TNF-alpha, IL-6 nor a combination of IL-1beta, TNF-alpha, IL-6 enhanced COX-1 mRNA levels in calvarial osteoblasts. A novel Src tyrosine kinase inhibitor, Herbimycin A (HERB), reduced COX-2 mRNA levels as well as PGE(2) production induced by IL-1beta, TNF-alpha and IL-6 or a combination of IL-1beta, TNF-alpha, IL-6, whereas COX-1 mRNA levels remained unaffected. Finally, HERB was found to inhibit in vitro bone resorption. These results indicate that the cooperative effects of IL-beta, TNF-alpha, IL-6 on PGE(2) production are due to the enhanced expression of the COX-2 gene and that tyrosine kinase(s) are involved in COX-2 signal transduction in mouse calvarial osteoblasts. Thus, the Src family of kinase inhibitors may be useful in treating diseases associated with elevated bone loss.

Regulation of gene expression by biotin (review)

In mammals, biotin serves as coenzyme for four carboxylases, which play essential roles in the metabolism of glucose, amino acids, and fatty acids. Biotin deficiency causes decreased rates of cell proliferation, impaired immune function, and abnormal fetal development. Evidence is accumulating that biotin also plays an important role in regulating gene expression, mediating some of the effects of biotin in cell biology and fetal development. DNA microarray studies and other gene expression studies have suggested that biotin affects transcription of genes encoding cytokines and their receptors, oncogenes, genes involved in glucose metabolism, and genes that play a role in cellular biotin homeostasis. In addition, evidence has been provided that biotin affects expression of the asialoglycoprotein receptor and propionyl-CoA carboxylase at the post-transcriptional level. Various pathways have been identified by which biotin might affect gene expression: activation of soluble guanylate cyclase by biotinyl-AMP, nuclear translocation of NF-kappaB (in response to biotin deficiency), and remodeling of chromatin by biotinylation of histones. Some biotin metabolites that cannot serve as coenzymes for carboxylases can mimic biotin with regard to its effects on gene expression. This observation suggests that biotin metabolites that have been considered "metabolic waste" in previous studies might have biotin-like activities. These new insights into biotin-dependent gene expression are likely to lead to a better understanding of roles for biotin in cell biology and fetal development.

IL-1beta induces and TGF-beta reduces vitamin D3-induced bone resorption in mouse calvarial bone cells

Bone cells produce multiple growth factors and cytokines that have effects on bone metabolism and can be incorporated into the bone matrix. The present study was designed to extend these observations by examining the interactions between transforming growth factor-beta (TGF-beta) or interleukin-1beta (IL-1beta) and bone cells in a rat long bone culture model. IL-1beta regulates several activities of the osteoblast cells derived from rat long bone explants in vitro. IL-1beta stimulated cellular proliferation and the synthesis of prostaglandin E2 and plasminogen activator activity in the cultured cells in a dose-dependent manner. TGF-B is present in the bone matrix and potentially can be released during bone resorption. TGF-beta reduced basal bone resorption and inhibited vitamin D3 [1,25(OH)2D3]-induced bone resorption in rat long bone cells. These studies support the role of IL-1beta in the pathological modulation of bone cell metabolism, with regard to implication in the pathogenesis of osteoporosis by IL-1beta, and that TGF-beta is positively inhibiting the bone resorption.

Biotin supplementation increases expression of genes encoding interferon-gamma, interleukin-1beta, and 3-methylcrotonyl-CoA carboxylase, and decreases expression of the gene encoding interleukin-4 in human peripheral blood mononuclear cells

Stimulation of immune cells by antigens triggers changes in the transcription of genes encoding cytokines and other proteins; these changes in gene expression are part of the normal immune response. Previous studies have provided evidence that biotin status may affect secretion of cytokines by immune cells. Here we determined whether biotin supplementation affects gene expression in human immune cells. Peripheral blood mononuclear cells were isolated from healthy adults before and after supplementation with 8.8 micro mol biotin/d for 21 d. Cells were cultured ex vivo with concanavalin A for 21 h to simulate stimulation with antigens. Expression of genes that play roles in cytokine metabolism, cell proliferation, signal transduction, stress response, apoptosis and biotin homeostasis was quantified by using DNA microarrays and reverse transcriptase-polymerase chain reaction. The abundance of mRNA encoding interferon-gamma, interleukin-1beta, and 3-methylcrotonyl-CoA carboxylase was 4.3, 5.6 and 8.9 times greater, respectively, after supplementation with biotin compared with before supplementation. In contrast, the abundance of mRNA encoding interleukin-4 was 6.8 times greater before supplementation than after supplementation. These data suggest that biotin supplementation affects gene expression in human immune cells. Effects of biotin on gene expression are likely to modulate the response of immune cells to antigens.