Chandran Preeja, Chandramohan Khaviyaa, Iyer Krithika, Balachandran Sreelakshmi Kokkatt, Michael Felicia Mary, Venkatachalam Sankar
Department of Anatomy, Dr. Arcot Lakshmanasamy Mudaliar Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, 600 113, India.
Biochem Biophys Res Commun. 2025 Sep 8;778:152373. doi: 10.1016/j.bbrc.2025.152373. Epub 2025 Jul 16.
Delayed cell death following contusion spinal cord injury (SCI) is mediated through multiple, overlapping apoptotic pathways, including intrinsic, extrinsic, and granzyme-mediated cascades. Mitochondrial permeability transition pore (mPTP) opening plays a central role in the intrinsic pathway by compromising mitochondrial membrane integrity and enabling the release of cytochrome C and apoptosis-inducing factor (AIF), which activate caspase-dependent and -independent mechanisms. In this study, a holistic approach to preventing the intrinsic pathway of apoptosis was undertaken by inhibiting mPTP gating through targeting the responsible proteins, namely, both BAX and BID, key pro-apoptotic Bcl-2 family proteins, along with cyclosporine A, a known inhibitor of the VDAC-ANT-Cyp-D pore complex. In a rodent model of thoracic contusion SCI, intraparenchymal administration of these inhibitors was followed by Western blot analysis of pathway-specific apoptotic markers at 3 and 7 days post-injury. The results demonstrated effective attenuation of intrinsic apoptosis, accompanied by a collateral reduction in extrinsic and granzyme-mediated pathways. Importantly, this inhibition of apoptosis did not exacerbate necrotic progression, indicating a selective and beneficial modulation of secondary cell death mechanisms. These findings provide initial evidence supporting mitochondrial pore-targeted strategies as a promising therapeutic avenue to mitigate apoptosis-driven secondary damage following SCI. Interestingly, it appears targeting just one pathway of apoptosis itself can produce more beneficial effects by collateral inhibition of other pathways as well. Further studies would be required to validate whether the molecular level benefits observed transulate into systemic improvement in functional recovery after contusion SCI.
脊髓挫伤性损伤(SCI)后的延迟性细胞死亡是通过多种重叠的凋亡途径介导的,包括内源性、外源性和颗粒酶介导的级联反应。线粒体通透性转换孔(mPTP)开放在内源性途径中起核心作用,它破坏线粒体膜的完整性,使细胞色素C和凋亡诱导因子(AIF)释放,从而激活半胱天冬酶依赖性和非依赖性机制。在本研究中,通过靶向负责的蛋白质(即促凋亡的Bcl-2家族关键蛋白BAX和BID)以及已知的VDAC-ANT-Cyp-D孔复合物抑制剂环孢素A来抑制mPTP门控,从而采取了一种整体方法来预防凋亡的内源性途径。在啮齿动物胸段挫伤性SCI模型中,在损伤后3天和7天对这些抑制剂进行实质内给药,随后对途径特异性凋亡标志物进行蛋白质印迹分析。结果表明内源性凋亡得到有效减弱,同时外源性和颗粒酶介导的途径也有相应减少。重要的是,这种对凋亡的抑制并没有加剧坏死进展,表明对继发性细胞死亡机制有选择性和有益的调节作用。这些发现提供了初步证据,支持将线粒体孔靶向策略作为减轻SCI后凋亡驱动的继发性损伤的一种有前景的治疗途径。有趣的是,似乎仅靶向凋亡的一条途径本身就可以通过对其他途径的间接抑制产生更有益的效果。需要进一步的研究来验证所观察到的分子水平益处是否能转化为挫伤性SCI后功能恢复的全身改善。