背景:减轻炎症损伤和抑制髓核(NP)凋亡被认为是逆转椎间盘退变(IDD)和缓解慢性腰痛的主要有效治疗思路。腺苷A2A受体(A2AR),作为G蛋白偶联受体家族的一员,在抗炎和缓解疼痛中起着重要作用。到目前为止,A2AR对IDD治疗的影响尚不清楚.本研究旨在探讨腺苷A2A受体(A2AR)在椎间盘退变(IDD)中的作用及潜在机制。
方法:采用IL-1β和针刺法建立碘缺乏病大鼠模型。A2AR激动剂CGS-21680和A2AR拮抗剂SCH442416用于研究IDD的治疗效果。组织学检查,采用Western印迹分析和RT-PCR方法评价A2AR与环磷酸腺苷(cAMP)/蛋白激酶A(PKA)通路的相关性。
结果:椎间盘组织A2AR活性以反馈方式上调,和cAMP,PKA和CREB表达也增加。但总的来说,IL-1β诱导的IDD显著上调炎症因子的表达。通过激活NF-κB信号通路,MMP3和Col-II下降导致髓核(NP)炎症加剧。A2AR激动剂CGS-21680通过显着增加A2AR活性而表现出椎间盘保护作用,然后进一步激活cAMP/PKA信号通路,通过下调NF-κB抑制TNF-α和IL-6的释放。相比之下,SCH442416抑制A2AR激活,与cAMP和PKA的较低表达水平一致,进一步导致IDD的加速。
结论:A2AR的激活可以预防炎症反应并减轻IDD的降解,因此提示了IDD的潜在新治疗策略。
BACKGROUND: Reduction of inflammatory damage and inhibition of nucleus pulposus (NP) apoptosis are considered to be the main effective therapy idea to reverse the intervertebral disc degeneration (IDD) and alleviate the chronic low back pain. The adenosine A2A receptor (A2AR), as a member of G protein-coupled receptor families, plays an important role in the anti-inflammation and relieving pain. So far, the impact of A2AR on IDD therapy is unclear. The aim of this study was to explore the role of Adenosine A2A receptor (A2AR) in the intervertebral disc degeneration (IDD) and clarify potential mechanism.
METHODS: IL-1β and acupuncture was used to establish IDD model rats. A2AR agonist CGS-21680 and A2AR antagonist SCH442416 were used to investigate the therapeutical effects for IDD. Histological examination, western blotting analysis and RT-PCR were employed to evaluate the the association between A2AR and cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway.
RESULTS: A2AR activity of the intervertebral disc tissues was up-regulated in feedback way, and cAMP, PKA and CREB expression were also increased. But in general, IL-1β-induced IDD promoted the significant up-regulation the expression of inflammatory factors. The nucleus pulposus (NP) inflammation was exacerbated in result of MMP3 and Col-II decline through activating NF-κB signaling pathway. A2AR agonist CGS-21680 exhibited a disc protective effect through significantly increasing A2AR activity, then further activated cAMP/PKA signaling pathway with attenuating the release of TNF-α and IL-6 via down-regulating NF-κB. In contrast, SCH442416 inhibited A2AR activation, consistent with lower expression levels of cAMP and PKA, further leading to the acceleration of IDD.
CONCLUSIONS: The activation of A2AR can prevent inflammatory responses and mitigates degradation of IDD thus suggest a potential novel therapeutic strategy of IDD.