School of Biomedicine, Faculty of Medical and Human Sciences, University of Manchester, Manchester M139PL, UK.
Arthritis Res Ther. 2011 Jan 28;13(1):R8. doi: 10.1186/ar3229.
Recent evidence suggests that intervertebral disc (IVD) cells derived from degenerative tissue are unable to respond to physiologically relevant mechanical stimuli in the 'normal' anabolic manner, but instead respond by increasing matrix catabolism. Understanding the nature of the biological processes which allow disc cells to sense and respond to mechanical stimuli (a process termed 'mechanotransduction') is important to ascertain whether these signalling pathways differ with disease. The aim here was to investigate the involvement of interleukin (IL)-1 and IL-4 in the response of annulus fibrosus (AF) cells derived from nondegenerative and degenerative tissue to cyclic tensile strain to determine whether cytokine involvement differed with IVD degeneration.
AF cells were isolated from nondegenerative and degenerative human IVDs, expanded in monolayers and cyclically strained in the presence or absence of the cytokine inhibitors IL-1 receptor antagonist (IL-1Ra) or IL-4 receptor antibody (IL-4RAb) with 10% strain at 1.0 Hz for 20 minutes using a Flexcell strain device. Total RNA was extracted from the cells at time points of baseline control and 1 or 24 hours poststimulation. Quantitative real-time polymerase chain reaction was used to analyse the gene expression of matrix proteins (aggrecan and type I collagen) and enzymes (matrix metalloproteinase 3 (MMP3) and a disintegrin and metalloproteinase with a thrombospondin type 1 motif 4 (ADAMTS4)).
Expression of catabolic genes (MMP3 and ADAMTS4) decreased in AF cells derived from nondegenerative tissue in response to 1.0-Hz stimulation, and this decrease in gene expression was inhibited or increased following pretreatment of cells with IL-1Ra or IL-4RAb respectively. Treatment of AF cells derived from degenerative tissue with an identical stimulus (1.0-Hz) resulted in reduced anabolic gene expression (aggrecan and type I collagen), with IL-1Ra or IL-4RAb pretreatment having no effect.
Both IL-1 and IL-4 are involved in the response of AF cells derived from nondegenerative tissue to 1.0-Hz cyclic tensile strain. Interestingly, the altered response observed at 1.0-Hz in AF cells from degenerative tissue appears to be independent of either cytokine, suggesting an alternative mechanotransduction pathway in operation.
最近的证据表明，来源于退行性组织的椎间盘中的细胞不能以正常的合成代谢方式对生理相关的机械刺激作出反应，而是通过增加基质分解代谢来作出反应。了解允许椎间盘细胞感知和响应机械刺激的生物学过程的本质（这一过程称为“力学转导”）对于确定这些信号通路是否因疾病而异是很重要的。这里的目的是研究白细胞介素（IL）-1 和 IL-4 是否参与源自非退行性和退行性组织的纤维环（AF）细胞对周期性张应变的反应，以确定细胞因子的参与是否因椎间盘退变而异。
从非退行性和退行性人椎间盘分离 AF 细胞，在单层中扩增，并在存在或不存在细胞因子抑制剂白细胞介素 1 受体拮抗剂（IL-1Ra）或白细胞介素 4 受体抗体（IL-4RAb）的情况下，使用 Flexcell 应变装置以 1.0 Hz 的频率施加 10%的应变 20 分钟。在刺激后的基线对照和 1 或 24 小时的时间点，从细胞中提取总 RNA。使用实时定量聚合酶链反应分析基质蛋白（聚集蛋白和 I 型胶原）和酶（基质金属蛋白酶 3（MMP3）和带有血小板反应蛋白 1 型基序的解整合素和金属蛋白酶 4（ADAMTS4））的基因表达。
在响应 1.0-Hz 刺激时，来源于非退行性组织的 AF 细胞中的分解代谢基因（MMP3 和 ADAMTS4）的表达减少，并且在用 IL-1Ra 或 IL-4RAb 预处理细胞后，这种基因表达的减少被抑制或增加。用相同刺激（1.0-Hz）处理来源于退行性组织的 AF 细胞导致合成代谢基因（聚集蛋白和 I 型胶原）的表达减少，而用 IL-1Ra 或 IL-4RAb 预处理没有影响。
IL-1 和 IL-4 均参与了源自非退行性组织的 AF 细胞对 1.0-Hz 周期性张应变的反应。有趣的是，在退行性组织来源的 AF 细胞中观察到的在 1.0-Hz 时的改变反应似乎独立于任何一种细胞因子，这表明存在替代的力学转导途径。
