The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, Hubei, China.
The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, Hubei, China.
J Endod. 2023 Dec;49(12):1641-1651.e6. doi: 10.1016/j.joen.2023.09.007. Epub 2023 Sep 27.
Human dental pulp stem cells (hDPSCs) reside in specialized microenvironments in the dental pulp, termed "niches," which are composed of diverse cellular components including nerves. Sensory nerves can positively regulate the expansion and differentiation of pulp cells, while the biological effects of the sympathetic nervous system (SNS) on hDPSCs remain elusive. This study is devoted to investigating the effects and underlying mechanisms of the SNS on the proliferation and migration of hDPSCs.
The distribution of sympathetic nerve fibers in human dental pulp was examined by immunofluorescence staining of tyrosine hydroxylase. The concentration of norepinephrine in healthy and carious human dental pulp tissues was detected using enzyme-linked immunosorbent assay. RNA-sequencing was applied to identify the dominant sympathetic neurotransmitter receptor in hDPSCs. Seahorse metabolic assay, adenosine triphosphate assay, lactate assay, and mitochondrial DNA copy number were performed to determine the level of glycometabolism. Transwell assay, wound healing assay, 5-ethynyl-2'-deoxyuridine staining assay, cell cycle assay, and Cell Counting Kit-8 assay were conducted to analyze the migratory and proliferative capacities of hDPSCs.
Sprouting of sympathetic nerve fibers and an increased concentration of norepinephrine were observed in inflammatory pulp tissues. Sympathetic nerve fibers were mainly distributed along blood vessels, and aldehyde dehydrogenase 1-positive hDPSCs resided in close proximity to neurovascular bundles. ADRA1B was identified as the major sympathetic neurotransmitter receptor expressed in hDPSCs, and its expression was enhanced in inflammatory pulp tissues. In addition, the SNS inhibited the proliferation and migration of hDPSCs through metabolic reprogramming via ADRA1B and its crosstalk with serine-threonine kinase and p38 mitogen-activated protein kinase signaling pathways.
This study demonstrates that the SNS can shift the metabolism of hDPSCs from oxidative phosphorylation to anaerobic glycolysis via ADRA1B and its crosstalk with serine-threonine kinase and p38 mitogen-activated protein kinase signaling pathways, thereby inhibiting the proliferative and migratory abilities of hDPSCs. This metabolic shift may facilitate the maintenance of the quiescent state of hDPSCs.
人牙髓干细胞（hDPSCs）位于牙髓的特殊微环境中，称为“龛”，由包括神经在内的多种细胞成分组成。感觉神经可以正向调节牙髓细胞的扩增和分化，而交感神经系统（SNS）对 hDPSCs 的生物学影响仍不清楚。本研究致力于研究 SNS 对 hDPSCs 增殖和迁移的影响及其潜在机制。
通过酪氨酸羟化酶免疫荧光染色检测人牙髓中交感神经纤维的分布。采用酶联免疫吸附试验检测健康和龋坏人牙髓组织中去甲肾上腺素的浓度。应用 RNA 测序鉴定 hDPSCs 中主要的交感神经递质受体。通过 Seahorse 代谢分析、三磷酸腺苷测定、乳酸测定和线粒体 DNA 拷贝数测定来确定糖代谢水平。通过 Transwell 测定、划痕愈合测定、5-乙炔基-2'-脱氧尿苷染色测定、细胞周期测定和细胞计数试剂盒-8 测定来分析 hDPSCs 的迁移和增殖能力。
在炎症性牙髓组织中观察到交感神经纤维的发芽和去甲肾上腺素浓度的增加。交感神经纤维主要分布在血管周围，醛脱氢酶 1 阳性 hDPSCs 与神经血管束相邻。ADRA1B 被鉴定为 hDPSCs 中表达的主要交感神经递质受体，其在炎症性牙髓组织中表达增强。此外，SNS 通过 ADRA1B 及其与丝氨酸-苏氨酸激酶和 p38 丝裂原活化蛋白激酶信号通路的串扰，通过代谢重编程抑制 hDPSCs 的增殖和迁移。
本研究表明，SNS 可以通过 ADRA1B 及其与丝氨酸-苏氨酸激酶和 p38 丝裂原活化蛋白激酶信号通路的串扰，将 hDPSCs 的代谢从氧化磷酸化转变为无氧糖酵解，从而抑制 hDPSCs 的增殖和迁移能力。这种代谢转变可能有助于维持 hDPSCs 的静止状态。
