Periodontal destruction and innate immunity via toll-like receptors

1)小鼠牙骨质细胞系(OCCM-30)、骨髓基质细胞系(ST_2)、原代颅骨成骨细胞系(OB)和巨噬细胞系(RAW)均表达Toll样受体。2)刺激TLR4通路可上调Toll样受体α、IL-6和RANKL的表达，下调OPG的表达。环氧合酶-2诱导产生的PGE2导致RANKL基因表达的第二个高峰。细胞对TLR5途径的反应与TLR4途径相似。有报道称，TLR4或TLR5通过共同的信号通路激活NF-αB，从而诱导炎性细胞因子如肿瘤坏死因子-κ、IL-6和IL-8的表达上调。TLR9途径与TLR4途径形成破骨细胞的机制可能不同。4)脂多糖刺激后24小时，ST2或OCCM-30细胞中TLR4基因表达下调。这一发现支持了免疫表达…的结果局部应用脂多糖后，体内牙周组织中TLR4的表达明显减少。而用CpG-ODN激活TLR9后，各时间点TLR9的表达水平无明显差异。这些结果表明，在牙周组织中，Toll样受体可能与牙周病原体攻击后的先天免疫诱导和牙周病的发生有关。5)单纯应用脂多糖不能像人牙周炎那样在牙周组织中诱导B细胞损伤。为此，每隔一周给L大鼠两次腹腔注射灭活细菌(伴生放线杆菌，AA 10 mg/只)。最后一次注射后1周，将50g/mlOMP-29和1 mg/mlAA-内毒素的混合液注入牙龈沟。虽然血清中OMP-29抗体水平升高，但牙周组织中未见B细胞病变。我们将继续尝试建立小鼠牙周炎模型。较少

1) Mouse cementoblast cell line (OCCM-30), bone marrow stromal cell line (ST2), primary calvarial osteoblast (OB) and macrophage cell line (RAW) constitutively expressed toll-like receptors.2) Stimulation of TLR4 pathway caused upregulation of TNF-α, IL-6 and RANKL mRNA and downregulation of OPG. The second peak of RANKL mRNA-expression caused by PGE2 production via cyclooxygenase-2 induction. Cell responses to TLR5 pathway were similar to those of TLR4 pathway. It was reported that stimulation of TLR4 or TLR5 induced upregulation of inflammatory cytokines production such as TNF-α, IL-6 and IL-8 resulted from NF-κB activation via common signaling pathway.3) TLR9 pathway induced upregulation of IFN mRNA in addition to TNF-α and RANKL mRNA. Mechanisms of osteoclastogenesis via TLR9 pathway may be different from TLR4 pathway.4) At 24 hours after LPS stimulation, downregulation of TLR4 mRNA level in ST2 or OCCM-30 cells was observed. The finding is supporting a result that the immuno-expre … More ssion of TLR4 was reduced in vivo periodontal tissue after topical application of LPS. On the other hand, after TLR9 activation with CpG-ODN there was no obvious difference in each TLR mRNA expression level. These findings indicate that in periodontal tissue toll-like receptors may be related to induction of innate immunity and development of periodontal disease after challenge of periodontal pathogens in a complex manner.5) Single application of LPS to rat gingival sulcus could not induce B cell lesion in periodontal tissue like human periodontitis. Therefore two times of intraperitoneal injection of killed bacteria (Actinobacillus Actinomycetemcomitans, Aa 10mg/l rat) were done with one week interval. At one week after last injection mixture solution of 50g/ml OMP-29 and 1mg/ml Aa-LPS was treated into gingival sulcus. Although increase of serum level of antibody to OMP-29 was detected, B cell lesion in periodontal tissue was not developed. We will continuously try to establish mouse periodontitis model. Less