Immunity system, nerve system ・ endocrine system in periodontitis

最近，有报道称，神经营养因子产生的非神经细胞是外周神经元的靶细胞。本研究以体外培养的人牙周膜细胞（HPDL）、人牙龈成纤维细胞（HGF）、人牙龈角质形成细胞（HGK）、人牙髓细胞（HPC）和人皮肤成纤维细胞（HSF）为研究对象，探讨了神经生长因子（NGF）、脑源性神经营养因子（BDNF）和神经营养因子-3（NT-3）及其受体TRKA、TRKB和TRKC在人牙周膜细胞（HPDL）、人牙龈成纤维细胞（HGF）、人牙龈角质形成细胞（HGK）、人牙髓细胞（HPC）和人皮肤成纤维细胞（HSF）中的表达情况。用聚合酶链反应（PCR）方法检测神经生长因子（NGF）、脑源性神经营养因子（BDNF）和神经营养因子-3（NT-3）及其受体TRKA、TRKB和TRKC的mRNA表达。所有神经营养素及其受体在牙周组织培养细胞中均有表达。HGK中的BDNF、HPDL中的TRKB、HGK中的NT-3和HPC-2中的TRKC在mRNA中几乎没有表达。接下来，我们研究了白细胞介素-1 β（IL-1）对各种神经营养因子及其受体mRNA表达的影响。HPC中的TRKA和HPDL中的NT-3呈增加趋势。但这些结果中的大多数可能并不显著。提示神经营养因子在牙周组织破坏阶段不起作用。本研究还应用原位杂交技术对牙周组织中各种神经营养因子及其受体的mRNA表达进行了研究。原位杂交结果与体外实验结果一致。而某些神经营养因子及其受体则分布于表皮的不同部位。提示神经营养因子可能以旁分泌的方式发挥作用，提示神经营养因子可能是牙周病病情变化的重要因素。

Recently, it has been reported that neurotrophic factors produced non-neural cells which are target cells of peripheral neurons. This study investigated whether nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) and their receptors respectively TRKA, TRKB and TRKC.In a cultured human periodontal ligament cells (HPDL), human gingival fibroblast cells (HGF) and human gingival keratinocytes (HGK), human dental pulp cells (HPC) and human skin fibroblasts (HSF), the mRNA encoding three representative neurotrophins, namely, verve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) and their receptors respectively TRKA, TRKB and TRKC were detected by polymerase chain reaction (PCR) method. All neurotorophins and receptors expressed in almost of cultured cells from periodontal tissue. BDNF in HGK, TRKB in HPDL, NT-3 IN HGK and TRKC in HPC-2 were not demonstrated mRNA almostly.Next, we investigated that the effects of interleukin-1 beta (IL-1) on mRNA demonstration of various neurotrophins and their receptors. TRKA in HPC and NT-3 in HPDL were shown a tendency to increase. But almost of these results might not be significantly. These results may show that neurotrophins do not act in the phase of destroy of periodontal tissue. Namely neurotrophins may promote at the regeneration of periodontal tissue.We also investigated that demonstration of mRNA of various neurotrophins and their receptors in periodontal tissue in vivo by in situ hybridization. Results of in situ hybridization were matched the results of in vitro experiment. Some neurotrophins and their receptors however were showed that various sites in the epidermis. This shows that neurotrophins may act in a paracrine manner.These results show that neurotrophins may act as important factor in the change of periodontal disease state.