Innate immune responses of the dental pulp to caries

Various cells and inflammatory mediators are involved in the initial pulpal responses to caries. This review focuses on the cellular, neuronal, and vascular components of pulpal innate responses to caries. Discussion will include dentinal fluid, odontoblasts, neuropeptides, and neurogenic inflammation, which are not classic immune components but actively participate in the inflammatory response as the caries progress pulpally. Summaries of innate immune cells as well as their cytokines and chemokines in healthy and reversible pulpitis tissues are presented.     

Update on the adaptive immune responses of the dental pulp

Recent advances in immunology have disclosed the enormous complexity of the immune regulatory system. The dental pulp is equipped to mount adaptive immune responses to caries, which include at least antigen-presenting cells, lymphocytes, mast cells and their cytokines, and chemokines. The purpose of this review is to summarize our current understanding of the roles of these cellular and molecular components in the irreversibly inflamed pulp. The immunopathology of abscess formation and the mechanisms for painless pulpitis are also discussed.     

Freeze-fracture electron microscopy of non-myelinated nerve fibres in the human dental pulp

Freeze-fracture replicas from the subodontoblast region gave a good three-dimensional comprehension of the structure of non-myelinated nerve fibres. Each Schwann cell ensheathed 1-15 axons with a mean diameter of 0.4 micron (0.1-1.2 micron). Many axons were not entirely ensheathed but were exposed to the extracellular space to various degrees. Tightening membrane specializations were not found in the mesaxons. The Schwann-cell plasmalemma exhibited caveolae with necks surrounded by evenly-sized intramembranous particles, typical of endocytosis. The nuclear envelope of Schwann cells showed a few typical pores and perinuclear cisterna. In tangential fractures, the axolemma displayed intramembranous particles evenly distributed over the axolemmal fracture planes. There was a marked difference in particle density between the P (600-650/micron2) and E (150-200/micron2) faces.     

炎症状态下人牙髓神经纤维内Ca^2＋浓度的变化

利用细胞内Ｃａ２＋浓度测定技术，直接测定了牙髓神经纤维内Ｃａ２＋浓度，结果发现：无论是临床炎症性痛过敏牙髓，或是炎症介质组织胺、５－羟色胺处理的牙髓，其神经纤维内Ｃａ２＋浓度均比正常牙髓显著升高。而当降低细胞外液Ｃａ２＋浓度时，虽经炎症介质处理，神经纤维内Ｃａ２＋浓度与正常组无显著差异。说明牙髓神经纤维内Ｃａ２＋升高可能与其炎性痛过敏的发生有关。增加的Ｃａ２＋可能来源于细胞外液的Ｃａ２＋跨膜通道内流     

Feline dental pulp photoplethysmography during stimulation of vasomotor nerve supply

The effect of cervical sympathetic nerve stimulation on circulation of the tooth pulp of cats was studied by photoplethysmography. Responses induced by electrical stimulation of varying intensity (voltage), frequency and pulse duration were compared and analysed. Effective stimulation was obtained at frequencies of more than 3 c/s and at intensities of more than 0.3 V. Periapical injection of xylocaine caused disappearance of the changes on the photoplethysmographic records induced by sympathetic nerve stimulation. The blocking effect of xylocaine was reversible. The photoplethysmographic changes observed are discussed in terms of activation of series-coupled vascular segments in an encapsulated organ.     

大鼠牙髓中谷氨酸能神经纤维的定性研究

目的:为了明确牙髓中有无谷氨酸(Glutamate,Glu)能神经纤维的存在,以探讨牙痛信息传递机制。方法:自大鼠牙髓腔内注入逆行追踪剂辣根过氧化物酶—麦胚凝集素(HRP-WGA),数天后取三叉神经节做HRP呈色Glu免疫组化反应,观察支配大鼠牙髓的初级感觉传入神经元所在的三叉神经节中是否存在辣根过氧化物酶(HRP)和Glu双标细胞。结果:三叉神经节眼上颌部内可见HRP单标、Glu单标、HRP-Glu双标三种细胞。结论:大鼠牙髓中存在Glu能的神经末梢     

Vascular and cellular responses to pro-inflammatory stimuli in rat dental pulp

Dental pulp reactivity to various pro-inflammatory stimuli was independently evaluated in rats in terms of a vascular permeability increase and leukocyte recruitment. Substance P, calcitonin-gene related peptide (CGRP) and prostaglandin E(2) (in the picomol range) were applied to the exposed pulp from anesthetised animals and the plasma extravasation measured by the Evans blue content in the tissue following 10 min of administration. Leukocyte recruitment was evaluated morphometrically by counting the cell number present in serial sections of 1:3 4 microm pulp tissue 6 h after bacterial endotoxin (LPS; 0.06-1.2 microg/site) administration. Increase in pulp vascular permeability and cellular recruitment due to the injection of mentioned mediators in the skin or LPS in the peritoneal cavity were used as positive controls. Increase in vascular permeability in the pulp occurred in the same dose-range as observed in the skin, being CGRP the most active substance in both cases. However, it was necessary a higher dose of LPS (1.2 microg) to induce a similar cell recruitment in the pulp as that observed in the rat peritoneal cavity (0.3 microg). These data indicate that dental pulp reactivity presents the same pattern of increase in vascular permeability to other tissues in the rat, being CGRP the most potent mediator in this respect. In addition, they suggest the presence of CGRP receptors in the dental pulp. However, an adequate leukocyte recruitment response to bacterial endotoxin was not mounted, suggesting a deficiency in adhesion molecules in blood vessels in the rat dental pulp.     

牙髓干细胞在周围神经损伤修复中的研究进展

周围神经损伤(peripheral nerves injury,PNI)是口腔临床常见病,极易造成患者功能丧失和美观异常,牙髓干细胞(dental pulp stem cells,DPSCs)结合组织工程在PNI修复中的应用是目前研究热点.DPSCs具有来源丰富、提取简单、免疫原性低以及体外增殖率高等优点,其可分化成雪...     

Membrane architecture of myelinated nerve fibres in the human dental pulp studied by freeze-fracturing

The outer surface of the myelin sheath was well visualized in electron micrographs of replicas and the distribution of its cytoplasm-containing portions could be analysed. Numerous caveolae, probably representing the surface stomata of endo- or exocytotic vesicles were found on the plasmalemmal surface overlying organelle-rich cytoplasmic regions. Membrane specializations of the tight-junction type were found at the outer and inner mesaxons of the myelin sheath as well as at the Ranvier node and Schmidt-Lanterman incisures. Presuming that so-called leakiness is related to the junctional morphology, these junctions would be classified as moderately leaky. The morphological features of the Schwann-cell nuclear envelope were essentially as described for other mammalian cells.