Adult hippocampal dentate granule neurons are generated from neural stem cells (NSCs) in the mammalian brain, and the fate specification of adult NSCs is precisely controlled by the local niches and environment, such as the subventricular zone (SVZ), dentate gyrus (DG), and Toll-like receptors (TLRs). Epigallocatechin-3-gallate (EGCG) is the main polyphenolic flavonoid in green tea that has neuroprotective activities, but there is no clear understanding of the role of EGCG in adult neurogenesis in the DG after neuroinflammation. Here, we investigate the effect and the mechanism of EGCG on adult neurogenesis impaired by lipopolysaccharides (LPS). LPS-induced neuroinflammation inhibited adult neurogenesis by suppressing the proliferation and differentiation of neural stem cells in the DG, which was indicated by the decreased number of Bromodeoxyuridine (BrdU)-, Doublecortin (DCX)- and Neuronal Nuclei (NeuN)-positive cells. In addition, microglia were recruited with activatingTLR4-NF-κB signaling in the adult hippocampus by LPS injection. Treating LPS-injured mice with EGCG restored the proliferation and differentiation of NSCs in the DG, which were decreased by LPS, and EGCG treatment also ameliorated the apoptosis of NSCs. Moreover, pro-inflammatory cytokine production induced by LPS was attenuated by EGCG treatment through modulating the TLR4-NF-κB pathway. These results illustrate that EGCG has a beneficial effect on impaired adult neurogenesis caused by LPSinduced neuroinflammation, and it may be applicable as a therapeutic agent against neurodegenerative disorders caused by inflammation.
Periodontal disease is one of the most prevalent chronic disorders worldwide. It is accompanied by inflammation of the gingiva and destruction of periodontal tissues, leading to alveolar bone loss. Here, we focused on the role of adipokines, which are locally expressed by periodontal tissues, in the regulation of catabolic gene expression leading to periodontal inflammation. The expression of the nicotinamide phosphoribosyltransferase (NAMPT) adipokine was dramatically increased in inflamed human and mouse gingival tissues. NAMPT expression was also increased in lipopolysaccharide- and proinflammatory cytokine-stimulated primary cultured human gingival fibroblasts (GF). Adenovirus-mediated NAMPT (Ad-Nampt) overexpression upregulated the expression and activity of COX-2, MMP1 and MMP3 in human GF. The upregulation of IL-1β- or Ad-Nampt-induced catabolic factors was significantly abrogated by the intracellular NAMPT (iNAMPT) inhibitor, FK866 or by the sirtuin (SIRT) inhibitor, nicotinamide (NIC). Recombinant NAMPT protein or extracellular NAMPT (eNAMPT) inhibition using a blocking antibody did not alter NAMPT target gene expression levels. Moreover, intragingival Ad-Nampt injection mediated periodontitis-like phenotypes including alveolar bone loss in mice. SIRT2, a part of the SIRT family, was positively associated with NAMPT actions in human GF. Furthermore, in vivo inhibition of the NAMPT-NAD+-SIRT axis by NIC injection in mice ameliorated the periodontal inflammation and alveolar bone erosion caused by intragingival injection of Ad-Nampt. Our findings indicate that NAMPT is highly upregulated in human GF, while its enzymatic activity acts as a crucial mediator of periodontal inflammation and alveolar bone destruction via regulation of COX-2, MMP1, and MMP3 levels.
BackgroundDisplacement of dental implants into the maxillary sinus is rare, but it primarily occurs in patients with severe pneumatization of the maxillary sinus and/or deficiency of the alveolar process. Some complications such as the infection of the paranasal sinuses and formation of the oroantral fistula can be followed by the displacement of a dental implant. Therefore, the displaced implant has to be removed immediately with surgical intervention show and another plan for rehabilitation should be considered.Main bodyThe conventional procedure for the removal of a displaced implant from the maxillary sinus involves sinus bone grafting and new implant placement performed in two or more steps with a significant time gap in between. Simplification of these surgical procedures can decrease the treatment duration and patient discomfort.ConclusionsIn this review, we discuss the anatomical characteristics of the maxillary sinus and the complications associated with implant displacement into the sinus.
Gwangju,Introduction: This study examined the effect of recombinant human bone morphogenetic protein (rhBMP)-2 and β -tricalcium phosphate (β -TCP) on new bone formation in a rabbit calvarium using a rapid prototype titanium cap (RP Ti cap).
Materials and Methods:Eight New Zealand white rabbits were used in this study. Hemispherical RP Ti caps (10 mm in diameter) were implanted subperiosteally on the rabbit calvaria. β -TCP was filled in the RP Ti cap in the control group, and rhBMP-2 soaked β -TCP was used in experimental group. The rabbits were sacrificed 2 and 4 weeks after the operation. The volume and pattern of newly formed bone was analyzed by micro computed tomography (CT). Results: Macroscopically, there were no abnormal findings in any of the animals. The micro CT images revealed new bone from the calvaria that expanded gradually toward the top of the titanium cap, particularly along the inner surface of the titanium cap in the experimental group at 4 weeks after grafting. There was no significant difference in new bone volume ratio between the control and experimental groups at 2 weeks after grafting. There was a statistically significant difference in the new bone volume ratio between the experimental (14.1±1.8 %) and control (7.2±1.5 %) groups at 4 weeks after grafting (P<0.01).
Conclusion:The RP Ti cap can effectively guide new bone formation and rhBMP-2 can induce the new bone formation.
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