The sphingosine-1-phosphate receptor 1 binding molecule FTY720 inhibits osteoclast formation in rats with ligature-induced periodontitis.

BACKGROUND AND OBJECTIVE: Osteoclast precursors (OPs) re-migrate from the bone surface into blood vessels through sphingosine-1-phosphate receptor 1 (S1PR1) expression. T cells also express S1PR1, mediating their migration from the lymph nodes into blood vessels. OP and T-cell migration are one of the sequential steps related to osteoclast formation. To characterize the role of S1PR1 in osteoclast formation induced by periodontitis, we investigated the effect of S1PR1-binding molecule FTY720 (FTY) on the number of OPs and T cells in periodontal tissue and peripheral blood of rats with ligature-induced periodontitis. MATERIAL AND METHODS: Rats were divided into four groups; control (Con), FTY, periodontitis (Peri), and periodontitis+FTY (Peri+FTY) groups. Ligatures were placed around the first molars in the left and right mandibles. The rats were intraperitoneally injected with vehicle or 3 mg/kg FTY daily until they were killed. The number of osteoclasts and cluster of differentiation (CD)11b, CD3 and receptor activator of NF-κB ligand (RANKL)-positive cells in first molar furcation were counted by tartrate-resistant acid phosphatase or immunohistochemistry staining. The number of CD11b- and CD3-positive cells in peripheral blood was estimated by flow cytometry. RESULTS: The number of osteoclasts in the Peri group was higher than Con, Peri+FTY and FTY groups (p < 0.05) and CD11b, CD3 and RANKL-positive cells were also higher in the Peri group than other groups in furcation (p < 0.05). While CD11b-positive cells in furcation of the Peri+FTY group were lower than the Peri group (p < 0.05), they were higher in peripheral blood (p < 0.05). Dissimilar to CD11b-positive cells, CD3-positive cells in the Peri+FTY group were lower in peripheral blood as well as furcation than the Peri group (p < 0.05). RANKL-positive cells in furcation of the Peri+FTY group were also lower than Peri group (p < 0.05). CONCLUSION: These results indicate that FTY may facilitate re-migration of OPs from the alveolar bone surface into blood vessels, blocking T-cell migration from the lymph nodes into blood vessels and subsequently reducing osteoclast formation induced by periodontitis. This suggests that S1PR1-S1P binding may play a role in osteoclast formation of periodontitis by modulating OP and T-cell migration.

Periodontitis mainly increases osteoclast formation via enhancing the differentiation of quiescent osteoclast precursors into osteoclasts.

BACKGROUND AND OBJECTIVES: Tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclasts are formed in sequential steps: proliferation and differentiation of hematopoietic progenitors into quiescent osteoclast precursors (QOPs), followed by fusion of QOPs. In this study, we investigated whether enhancement of osteoclast formation by periodontitis is derived from the stimulation of proliferation of hematopoietic progenitors or the differentiation of QOPs into osteoclasts. MATERIAL AND METHODS: Ligatures were placed around the first molars in the left mandibles of Fischer 344 inbred rats. The rats received drinking water containing bromodeoxyuridine (BrdU) (which can be incorporated into dividing nuclei) after ligation during the experimental period. The number of inflammatory cells in the distal area was counted. Alveolar bone loss was histologically estimated by measuring the distance from the cementoenamel junction to the alveolar bone crest in the distal area and determining the percentage of periodontal ligament area in the furcation. The number of osteoclasts and percentage of BrdU(+) nuclei in total osteoclasts nuclei were counted after TRAP and BrdU double labeling. RESULTS: The number of polymorphonuclear cells increased on day 1 and then rapidly decreased. The number of mononuclear cells increased in a time-dependent manner up to day 5 and remained the same until day 10. Alveolar bone loss of ligatured teeth increased in a time-dependent manner. The number of osteoclasts peaked on day 3 then gradually decreased. At peak, the percentage of BrdU(+) nuclei in total osteoclasts nuclei in the distal and furcation areas were 7.9% and 4.1%, respectively. CONCLUSION: These results indicate that most of the osteoclasts formed after periodontitis induction are derived from preformed QOPs, suggesting that enhancement of osteoclast formation by periodontitis might be mainly caused by stimulating the differentiation of QOPs into osteoclasts.

ADAR2-dependent GluA2 editing regulates cocaine seeking.

Activation of AMPA receptors (AMPARs) in the nucleus accumbens is necessary for the reinstatement of cocaine-seeking behavior, an animal model of drug craving and relapse. AMPARs are tetrameric protein complexes that consist of GluA1-4 subunits, of which GluA2 imparts calcium permeability. Adenosine deaminase acting on RNA 2 (ADAR2) is a nuclear enzyme that is essential for editing GluA2 pre-mRNA at Q/R site 607. Unedited GluA2(Q) subunits form calcium-permeable AMPARs (CP-AMPARs), whereas edited GluA2(R) subunits form calcium-impermeable channels (CI-AMPARs). Emerging evidence suggests that the reinstatement of cocaine seeking is associated with increased synaptic expression of CP-AMPARs in the nucleus accumbens. However, the role of GluA2 Q/R site editing and ADAR2 in cocaine seeking is unclear. In the present study, we investigated the effects of forced cocaine abstinence on GluA2 Q/R site editing and ADAR2 expression in the nucleus accumbens. Our results demonstrate that 7 days of cocaine abstinence is associated with decreased GluA2 Q/R site editing and reduced ADAR2 expression in the accumbens shell, but not core, of cocaine-experienced rats compared with yoked saline controls. To examine the functional significance of ADAR2 and GluA2 Q/R site editing in cocaine seeking, we used viral-mediated gene delivery to overexpress ADAR2b in the accumbens shell. Increased ADAR2b expression in the shell attenuated cocaine priming-induced reinstatement of drug seeking and was associated with increased GluA2 Q/R site editing and surface expression of GluA2-containing AMPARs. Taken together, these findings support the novel hypothesis that an increased contribution of accumbens shell CP-AMPARs containing unedited GluA2(Q) promotes cocaine seeking. Therefore, CP-AMPARs containing unedited GluA2(Q) represent a novel target for cocaine addiction pharmacotherapies.

Diabetic characteristics and alveolar bone loss in streptozotocin- and streptozotocin-nicotinamide-treated rats with periodontitis.

BACKGROUND AND OBJECTIVE: Experimental models showing variable diabetic status are necessary to understand the relationship between diabetes and periodontitis. The streptozotocin (STZ)-induced diabetes model allows control of diabetic status by nicotinamide (NA), which protects against STZ-induced ß-cell necrosis. Therefore, we compared diabetic characteristics and alveolar bone loss in STZ- and STZ-NA-treated rats with periodontitis. MATERIAL AND METHODS: STZ-treated rats were generated by intravenous (IV) administration of STZ (50 mg/kg). STZ-NA-treated rats were induced by intraperitoneal administration of NA (270 mg/kg) 15 min before IV administration of STZ (65 mg/kg). Periodontitis was induced by ligature around the left mandibular first molar 1 wk after injection. Blood glucose level, glucose tolerance and serum insulin levels were determined at day 0 and/or 20 after ligature. At day 20, tibia bone loss was assessed using micro-computed tomography and hematoxylin and eosin staining. Alveolar bone loss was histologically measured as the distance of the cementoenamel junction to the alveolar bone crest in distal and the percentage of periodontal ligament area in the first molar furcation, respectively. The number of inflammatory cells, receptor activator of nuclear factor kappa-B ligand (RANKL)-positive cells and the area of osteoid were determined. RESULTS: In STZ-treated rats, obvious hyperglycemia over 300 mg/dL and severe body weight loss were observed. The insulin level was approximately 14% compared to that of control rats. STZ-NA-treated rats were impaired in glucose tolerance compared to control rats; however, body weight and insulin levels were not significantly different. Tibia bone loss was increased in STZ-treated rats, but significant change was not observed in STZ-NA-treated rats compared to control rats. In ligatured teeth, alveolar bone loss was increased in both STZ- and STZ-NA-treated rats compared to control rats. Alveolar bone loss, the number of inflammatory cells and RANKL-positive cells in STZ-treated rats were greater than in STZ-NA-treated rats. The area of osteoid decreased in STZ-treated rats compared to control, but not STZ-NA-treated rats. CONCLUSION: These results indicate that STZ- and STZ-NA-treated rats exhibit diabetic characteristics similar to type 1 diabetes mellitus and a pre-diabetic state, respectively. In addition, alveolar bone loss in response to periodontitis and tibia loss depend on diabetic status. Diabetic status-dependent bone remodeling imbalance and inflammation could affect the alveolar bone loss in the two models. Both STZ- and STZ-NA-treated rats may be useful to investigate differences in periodontitis sensitivity associated with diabetic status and to develop therapeutic agents for periodontitis in patients with diabetes.

Effects of dietary supplementation of citrus by-products fermented with a probiotic microbe on growth performance, innate immunity and disease resistance against Edwardsiella tarda in juvenile olive flounder, Paralichthys olivaceus (Temminck & Schlegel).

Two consecutive studies were conducted to evaluate the dietary supplementation of citrus by-products (CB) fermented with probiotic bacteria on growth performance, feed utilization, innate immune responses and disease resistance of juvenile olive flounder. In Experiment I, five diets were formulated to contain 0% (control) or 3% four different CB fermented with Bacillus subtilis (BS), Enterococcus faecium (EF), Lactobacillus rhamnosus (LR) and L. plantarum (LP) (designated as CON, CBF-BS, CBF-EF, CBF-LR and CBF-LP, respectively). During 10 weeks of a feeding trial, growth performance and feed efficiency were not significantly different among all the fish groups. However, fish fed CBF containing diets had significantly higher survivals than the CON group. Disease resistance of fish against Edwardsiella tarda was increased by the fermentation of CB. In Experiment II, we chose the BS as a promising probiotic and formulated five diets to contain 0%, 2%, 4%, 6% and 8% CBF-BS. Growth performance was not significantly affected by the CBF-BS supplementation during 6 weeks of a feeding trial. Innate immunity of fish was significantly enhanced by CBF-BS supplementation. Myeloperoxidase and lysozyme activities were increased in a dose-dependent manner by dietary CBF-BS inclusions. In a consecutive challenge test against E. tarda, an increased disease resistance was found by CBF-BS supplementation. These studies indicate that the fermentation process of CB with probiotic has beneficial effects on innate immunity and thereby increases disease resistance of olive flounder against E. tarda. Bacillus subtilis can be used as a promising probiotic microbe for by-product fermentation in fish feeds.

Effects of HB-EGF and epiregulin on wound healing of gingival cells in vitro.

OBJECTIVE: Gingival wound healing is important to periodontal disease and surgery. This in vitro study was conducted to assess the manner in which heparin-binding epidermal growth factor-like growth factor (HB-EGF) and epiregulin cooperatively participate in the wound-healing process in the gingival epithelial and fibroblast cells of the oral mucosa. MATERIAL AND METHODS: Gingival epithelium and fibroblast were separated from gingival tissue biopsies and prepared to primary cultures. The changes in the mRNA expression were evaluated via real-time PCR. The effects on cell proliferation, migration, and repopulation were evaluated in vitro. RESULTS: The different regulation of expressions of HB-EGF, epiregulin, and epidermal growth factor receptors was observed over time and with different gingival cell types. HB-EGF exerted a cell migration-inducing effect on both epithelial and fibroblast cells, whereas epiregulin did not. Both growth factors functioned as mitogens for epithelial cell proliferation, but not for fibroblast proliferation. HB-EGF strongly promoted epithelial cell repopulation and mildly promoted fibroblast repopulation, whereas epiregulin promoted only fibroblast repopulation. CONCLUSION: These results indicated that both growth factors might function importantly in the wound-healing process of human gingival tissue via the different regulation of the expression, cell migration, proliferation, and repopulation.

Td92, an outer membrane protein of Treponema denticola, induces osteoclastogenesis via prostaglandin E(2)-mediated RANKL/osteoprotegerin regulation.

BACKGROUND AND OBJECTIVE: Periodontitis is a chronic inflammatory disease of the periodontium that causes significant alveolar bone loss. Osteoclasts are bone-resorbing multinucleated cells. Osteoblasts regulate osteoclast differentiation by expression of RANKL and osteoprotegerin (OPG). Td92 is a surface-exposed outer membrane protein of Treponema denticola, a periodontopathogen. Although it has been demonstrated that Td92 acts as a stimulator of various proinflammatory mediators, the role of Td92 in alveolar bone resorption remains unclear. Therefore, in this study, we investigated the role of Td92 in bone resorption. MATERIAL AND METHODS: Mouse bone marrow cells were co-cultured with calvariae-derived osteoblasts in the presence or absence of Td92. Osteoclast formation was assessed by TRAP staining. Expressions of RANKL, osteoprotegerin (OPG) and prostaglandin E(2) (PGE(2) ) in osteoblasts were estimated by ELISA. RESULTS: Td92 induced osteoclast formation in the co-cultures. In the osteoblasts, RANKL and PGE(2) expressions were up-regulated, whereas OPG expression was down-regulated by Td92. The addition of OPG inhibited Td92-induced osteoclast formation. The prostaglandin synthesis inhibitors NS398 and indomethacin were also shown to inhibit Td92-induced osteoclast formation. The effects of Td92 on the expressions of RANKL, OPG and PGE(2) in osteoblasts were blocked by NS398 or indomethacin. CONCLUSION: These results suggest that Td92 promotes osteoclast formation through the regulation of RANKL and OPG production via a PGE(2) -dependent mechanism.

Inhibitory effect of evodiamine alone and in combination with rosiglitazone on in vitro adipocyte differentiation and in vivo obesity related to diabetes.

OBJECTIVE: Evodiamine (evo) has been shown to exert anti-inflammatory, antinociceptive and anticancer effects. In this study, we investigated the effects of evo alone and in combination with rosiglitazone (rosi) on in vitro adipocyte differentiation and in vivo obesity related to diabetes. METHODS: Adipocyte differentiation was investigated in vitro using 3T3-L1 and C3H10T1/2 cells. To determine the degree of differentiation, Oil Red O staining and reverse transcription-PCR were carried out. Four groups of db/db mice were treated intraperitoneally once per day with vehicle, evo, rosi and evo+rosi. The mice were killed after 14 days and the blood, liver and adipose tissue were analyzed. RESULTS: The presence of evo or evo combined with rosi during adipogenic induction has been shown to inhibit adipocyte differentiation to a significant degree, particularly at the commitment and early induction stages. The evo and evo+rosi groups of db/db mice evidenced significant reductions in body weight gain. The ratio of epididymal white adipocyte tissue weight to body weight of the evo group was also significantly reduced. It is important to note that in the evo+rosi treatment, blood glucose levels were reduced to a degree similar to that of the rosi group, and plasma insulin levels were reduced significantly better than that of rosi group. Furthermore, hepatic lesions associated with fat and glycogen deposition were morphologically improved in the evo and evo+rosi groups. CONCLUSION: The results of this study showed that evo exerts an inhibitory effect on in vitro adipocyte differentiation and in vivo obesity, and also an improvement effect on insulin resistance. These desirable effects of evo were noted even in the presence of rosi. These results indicate that evo improves the undesirable effects of rosi, including adipogenesis, body weight gain and hepatotoxicity, while preserving its desirable blood-glucose-lowering effect.

Effects of heparin-binding epidermal growth factor-like growth factor on cell repopulation and signal transduction in periodontal ligament cells after scratch wounding in vitro.

BACKGROUND AND OBJECTIVE: A growing amount of attention has been placed on periodontal regeneration and wound healing for periodontal therapy. This study was conducted in an effort to determine the effects of heparin-binding epidermal growth factor-like growth factor on cell repopulation and signal transduction in periodontal ligament cells after scratch wounding in vitro. MATERIAL AND METHODS: Human periodontal ligament cells were acquired from explant tissue of human healthy periodontal ligament. After the wounding of periodontal ligament cells, the change in expression of heparin-binding epidermal growth factor-like growth factor and epidermal growth factor receptors 1-4 mRNA was assessed. The effects of heparin-binding epidermal growth factor-like growth factor on periodontal ligament cell proliferation and repopulation were assessed in vitro via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and by photographing the injuries, respectively. Extracellular signal-regulated kinase (Erk)1/2, p38 and Akt phosphorylation was characterized via western blotting. RESULTS: Scratch wounding resulted in a significant up-regulation of heparin-binding epidermal growth factor-like growth factor mRNA expression, whereas wounding had no effect on the expression levels of epidermal growth factor receptors 1-4. Interestingly, no expression of epidermal growth factor receptors 2 and 4 was detectable prior to or after wounding. Heparin-binding epidermal growth factor-like growth factor treatment promoted the proliferation and repopulation of periodontal ligament cells. The scratch wounding also stimulated the phosphorylation of Erk1/2 and p38, but not of Akt, in periodontal ligament cells, and heparin-binding epidermal growth factor-like growth factor treatment applied after wounding amplified and extended the activations of Erk1/2 and p38, but not of Akt. Furthermore, Erk1/2 inhibition blocked the process of cell repopulation induced by heparin-binding epidermal growth factor-like growth factor, whereas the inhibition of p38 delayed the process. CONCLUSION: These results indicate that heparin-binding epidermal growth factor-like growth factor may constitute a critical factor in the wound healing of human periodontal ligament cells by a mechanism that requires the activation of Erk1/2 via specific interaction with epidermal growth factor receptor 1.

Glutamate receptor abnormalities in the YAC128 transgenic mouse model of Huntington's disease.

A yeast artificial chromosome (YAC) mouse model of Huntington's disease (YAC128) develops motor abnormalities, age-dependent striatal atrophy and neuronal loss. Alteration of neurotransmitter receptors, particularly glutamate and dopamine receptors, is a pathological hallmark of Huntington's disease. We therefore analyzed neurotransmitter receptors in symptomatic YAC128 Huntington's disease mice. We found significant increases in N-methyl-d-aspartate, AMPA and metabotropic glutamate receptor binding, which were not due to increases in receptor subunit mRNA expression levels. Subcellular fractionation analysis revealed increased levels of glutamate receptor subunits in synaptic membrane fractions from YAC128 mice. We found no changes in dopamine, GABA or adenosine receptor binding, nor did we see alterations in dopamine D1, D2 or adenosine A2a receptor mRNA levels. The receptor abnormalities in YAC128 transgenic mice thus appear limited to glutamate receptors. We also found a significant decrease in preproenkephalin mRNA in the striatum of YAC128 mice, which contrasts with the lack of change in levels of mRNA encoding neurotransmitter receptors. Taken together, the abnormal and selective increases in glutamate receptor subunit expression and binding are not due to increases in receptor subunit expression and may exert detrimental effects. The decrease in preproenkephalin mRNA suggests a selective transcriptional deficit, as opposed to neuronal loss, and could additionally contribute to the abnormal motor symptoms in YAC128 mice.

Huntingtin inclusions do not down-regulate specific genes in the R6/2 Huntington's disease mouse.

Transcriptional dysregulation is a central pathogenic mechanism in Huntington's disease (HD); HD and transgenic mouse models of HD demonstrate down-regulation of specific genes at the level of mRNA expression. Furthermore, neuronal intranuclear inclusions (NIIs) have been identified in the brains of R6/2 mice and HD patients. One possibility is that NIIs contribute to transcriptional dysregulation by sequestering transcription factors. We therefore assessed the relationship between NIIs and transcriptional dysregulation in the R6/2 mouse, using double-label in situ hybridization combined with immunohistochemistry, and laser capture microdissection combined with quantitative real-time PCR. There was no difference in transcript levels of specific genes between NII-positive and NII-negative neurons. These results demonstrate that NIIs do not cause decreases in D2, PPE and PSS mRNA levels in R6/2 striatum and therefore are not involved in the down-regulation of these specific genes in this HD model. In addition, these observations argue against the notion that NIIs protect against transcriptional dysregulation in HD.

Association between a G-protein beta 3 subunit gene polymorphism and the symptomatology and treatment responses of major depressive disorders.

The genes involved in signal transduction are major candidates in association studies on affective disorders and responses to antidepressants. We investigated whether the C825T polymorphism of the beta3 subunit of G protein (GNB3) gene is associated with the symptom severity or treatment response of major depressive disorders (MDDs) in a Korean sample of 106 MDD patients; our study also included 133 healthy controls. Hypertensive subjects were excluded from the study because association between GNB3 variants and hypertension has been reported in previous studies. We found significantly more carriers of the 825T allele in MDD patients than in normal controls (chi(2)=6.37, P=0.012; OR=2.19, 95% CI 1.18-4.05). The T-allele carriers showed higher scores than those with the CC genotype in the baseline total and in some subcategories of the Hamilton Depression Rating Scale (P<0.05). We also found a statistically significant association between T-allele carriers and antidepressant treatment response (P<0.05). These results suggest that the T allele of the C825T polymorphism in the GNB3 gene is associated with MDD. It was also demonstrated that MDD patients bearing the T allele had a severe symptomatology and a better response to antidepressant treatment than patients without the T allele.