Targeting Mitochondrial Oxidative Stress: Potential Neuroprotective Therapy for Spinal Cord Injury

Spinal cord injury (SCI) is a serious central nervous system (CNS) injury disease related to hypoxia-ischemia and inflammation. It is characterized by excessive reactive oxygen species (ROS) production, oxidative damage to nerve cells, and mitochondrial dysfunction. Mitochondria serve as the primary cellular origin of ROS, wherein the electron transfer chain complexes within oxidative phosphorylation frequently encounter electron leakage. These leaked electrons react with molecular oxygen, engendering the production of ROS, which culminates in the occurrence of oxidative stress. Oxidative stress is one of the common forms of secondary injury after SCI. Mitochondrial oxidative stress can lead to impaired mitochondrial function and disrupt cellular signal transduction pathways. Hence, restoring mitochondrial electron transport chain (ETC), reducing ROS production and enhancing mitochondrial function may be potential strategies for the treatment of SCI. This article focuses on the pathophysiological role of mitochondrial oxidative stress in SCI and evaluates in detail the neuroprotective effects of various mitochondrial-targeted antioxidant therapies in SCI, including both drug and non-drug therapy. The objective is to provide valuable insights and serve as a valuable reference for future research in the field of SCI.

Inhibition of Protease Activated Receptor 2 Attenuates HBx-Induced Inflammation and Mitochondria Oxidative Stress

BACKGROUND

Hepatitis B virus (HBV) infection is one of the global public problems. Among the known infection cases, HBV X protein (HBx) is one of the key inducements of viral replication and host infection. This study was aimed to uncover the role of protease activated receptor 2 (PAR2) on HBx-induced liver injury.

METHODS

A PAR2-KO mouse model expressing HBx was constructed using hydrodynamics-based in vivo gene transfection method. In addition, pcDNA3.1-HBx was used to over-express HBx in LO2 cells. The effects of HBx overexpression on inflammation and mitochondria oxidative stress were evaluated.

RESULTS

We found that PAR2 protein level was increased by HBx overexpression. The enforced HBx inhibited LO2 cells apoptosis. Meanwhile, HBx induced inflammation reactions through promoting the secretion of pro-inflammatory cytokines such as TNF-α, IL-6, and CXCL-2. Overexpressed HBx also resulted in mitochondria oxidative stress by upregulation of ROS level and downregulation of MMP and ATP. However, in FSLLRY-NH2 (PAR2 antagonist) treated LO2 cells or PAR2-KO mice, PAR2 blockade reversed the above adverse effects of HBx on liver cells or tissues.

CONCLUSION

Inhibition of PAR2 may suppress inflammation and mitochondria oxidative stress caused by HBx, pointing out the potential application values of PAR2 antagonist on the treatment of HBV infection in clinic.

Clostridium botulinum neurotoxin A induces apoptosis and mitochondrial oxidative stress via activation of TRPM2 channel signaling pathway in neuroblastoma and glioblastoma tumor cells

BACKGROUND

The Clostridium botulinum neurotoxin A (BTX) is a polypeptide produced by the bacterium Clostridium botulinum. In addition to the therapeutic actions of BTX against pain and neuromuscular disorders, it is acted as anticancerogenic effect through excessive mitochondria reactive oxygen species (ROS) production, apoptosis, and caspase activations. The TRPM2 cation channel is activated by ROS and ADP-ribose and it is inhibited by 2-aminoethyl diphenylborinate (2-APB) and N-(p-amylcinnamoyl) anthranilic acid (ACA). The aim of this study was an investigation of involvement BTX-induced TRPM2 activation on the mitochondria ROS production and apoptosis levels in the DBTRG glioblastoma and SH-SY5Y neuroblastoma tumor cells.

MATERIAL AND METHODS

The DBTRG and SH-SY5Y cells were divided into four groups as control, BTX (5 IU for 24 h), BTX + ACA (25 µM for 30 min), and BTX + 2-APB (100 µM for 30 min).

RESULTS

BTX treatment increased mitochondrial membrane depolarization (JC-1), mitochondrial (MitROS), and cytosolic (DHR123 and DCFH-DA) ROS levels, neuronal death (propidium iodide/Hoechst) rate, caspase -3, and -9 levels in the BTX group, although their levels were diminished in the BTX + ACA and BTX + 2-APB groups. The ACA and 2-APB treatments also decreased BTX-induced increase of TRPM2 cytosolic free Ca²⁺ concentration in the glioblastoma and neuroblastoma cell death.

CONCLUSIONS

BTX caused neuroblastoma and glioblastoma tumor cell death by activating the mitochondria ROS production via stimulating TRPM2 signaling pathways. BTX may serve as a potential therapeutic target via activation of TRPM2 for treating glioblastoma and neuroblastoma cells.