Department of Neurology, Hannover Medical School Hannover, Hannover, Germany.
J Neuroimmune Pharmacol. 2012 Dec;7(4):939-50. doi: 10.1007/s11481-012-9387-7. Epub 2012 Jul 21.
2-chlorodeoxyadenosine (CdA, Cladribine) is an immunosuppressant that has recently been shown to be effective in the treatment of multiple sclerosis (MS). There is extensive clinical experience with CdA for the treatment of neoplastic diseases, especially hematologic malignancies, due to its apoptotic effects on leukemic and several other neoplastic cells. Furthermore, CdA crosses the blood-brain-barrier and thus may also exert its effects directly on cells of the central nervous system (CNS). Therefore, we have studied the effects of CdA on cultured primary rat microglia, the resident macrophage in the CNS, which is also thought to be involved in the pathogenesis of MS. Treatment of microglia with CdA inhibited their proliferation and induced apoptosis. Phosphorylation of CdA to CdATP was required for both effects and was inhibited by deoxycytidine. Furthermore, activation of caspase-3 and -9 revealed the involvement of the intrinsic mitochondrial mediated apoptotic pathway. However, the absence of caspase-8 activation specified independency from the extrinsic death receptor mediated apoptosis. The mitochondrial membrane potential was significantly reduced after CdA exposure and was not conserved with Bax or caspase-3 inhibition. Assessment of DNA fragmentation by TUNEL and DNA-release-assay showed microglia with fragmented nuclei. Other functions of microglia like phagocytosis and LPS-induced NO and TNF-α release were not affected by CdA. These data suggest a potential of CdA treatment to induce not only leukopenia but also apoptosis in microglia in the CNS. These results help to understand the mechanism of action of CdA in CNS diseases and may open the possibility to target microglia.
2-氯脱氧腺苷（CdA，克拉屈滨）是一种免疫抑制剂，最近已被证明对多发性硬化症（MS）的治疗有效。由于其对白血病和其他几种肿瘤细胞的凋亡作用，CdA 在治疗肿瘤疾病方面已有广泛的临床经验，特别是血液系统恶性肿瘤。此外，CdA 可穿过血脑屏障，因此也可能直接对中枢神经系统（CNS）的细胞发挥作用。因此，我们研究了 CdA 对培养的原代大鼠小胶质细胞的作用，小胶质细胞是 CNS 中的常驻巨噬细胞，也被认为与 MS 的发病机制有关。CdA 处理小胶质细胞可抑制其增殖并诱导其凋亡。磷酸化 CdA 为 CdATP 是这两种作用所必需的，并且被脱氧胞苷抑制。此外，caspase-3 和 -9 的激活表明涉及内在的线粒体介导的凋亡途径。然而，caspase-8 激活的缺失指定了不依赖于外在的死亡受体介导的凋亡。CdA 暴露后线粒体膜电位显著降低，并且不能与 Bax 或 caspase-3 抑制相保守。通过 TUNEL 和 DNA 释放测定评估 DNA 片段化显示小胶质细胞具有碎片化的核。小胶质细胞的其他功能，如吞噬作用和 LPS 诱导的 NO 和 TNF-α 释放不受 CdA 影响。这些数据表明 CdA 治疗不仅可能诱导白细胞减少，而且可能诱导 CNS 中小胶质细胞的凋亡。这些结果有助于理解 CdA 在 CNS 疾病中的作用机制，并可能为靶向小胶质细胞开辟可能性。
