Critical role of mitochondrial aldehyde dehydrogenase 2 in acrolein sequestering in rat spinal cord injury

Hydralazine Promotes Central Nervous System Recovery after Spinal Cord Injury by Suppressing Oxidative Stress and Inflammation through Macrophage Regulation

OBJECTIVE

This study aims to investigate the effects of hydralazine on inflammation induced by spinal cord injury (SCI) in the central nervous system (CNS) and its mechanism in promoting the structural and functional recovery of the injured CNS.

METHODS

A compressive SCI mouse model was utilized for this investigation. Immunofluorescence and quantitative real-time polymerase chain reaction were employed to examine the levels of acrolein, acrolein-induced inflammation-related factors, and macrophages at the injury site and within the CNS. Western blotting was used to evaluate the activity of the phosphoinositide 3-kinase (PI3K)/AKT pathway to study macrophage regulation. The neuropathic pain and motor function recovery were evaluated by glutamic acid decarboxylase 65/67 (GAD65/67), vesicular glutamate transporter 1 (VGLUT1), paw withdrawal response, and Basso Mouse Scale score. Nissl staining and Luxol Fast Blue (LFB) staining were performed to investigate the structural recovery of the injured CNS.

RESULTS

Hydralazine downregulated the levels of acrolein, IL-1β, and TNF-α in the spinal cord. The downregulation of acrolein induced by hydralazine promoted the activation of the PI3K/AKT pathway, leading to M2 macrophage polarization, which protected neurons against SCI-induced inflammation. Additionally, hydralazine promoted the structural recovery of the injured spinal cord area. Mitigating inflammation and oxidative stress by hydralazine in the animal model alleviated neuropathic pain and altered neurotransmitter expression. Furthermore, hydralazine facilitated motor function recovery following SCI. Nissl staining and LFB staining indicated that hydralazine promoted the structural recovery of the injured CNS.

CONCLUSION

Hydralazine, an acrolein scavenger, significantly mitigated SCI-induced inflammation and oxidative stress in vivo, modulated macrophage activation, and consequently promoted the structural and functional recovery of the injured CNS.

Aldehyde dehydrogenase 2 polymorphism is associated with chemotherapy-related cognitive impairment in patients with breast cancer who receive chemotherapy

BACKGROUND

Chemotherapy-related cognitive impairment (CRCI) is a common but easily overlooked condition that markedly affects the quality of life (QOL) of patients with breast cancer. The rs671 is a common gene polymorphism of aldehyde dehydrogenase 2 (ALDH2) in Asia that is involved in aldehyde metabolism and may be closely related to CRCI. However, no study has yet summarised the association between ALDH2 and CRCI.

METHODS

This study enrolled one hundred and twenty-four patients diagnosed with breast cancer according to the pathology results, genotyped for ALDH2 single-nucleotide polymorphisms (SNP) to explore these. The mini-mental state exam (MMSE), verbal fluency test (VFT), and digit span test (DST) results were compared in these patients before and after chemotherapy (CT).

RESULTS

We found that patients with ALDH2 gene genotypes of rs671_GG, rs886205_GG, rs4648328_CC, and rs4767944_TT polymorphisms were more likely to suffer from cognitive impairment during chemotherapy. A trend toward statistical significance was observed for rs671_GG of DST (z = 2.769, p = 0.006), VFT (t = 4.624, P<0.001); rs886205_GG of DST (z = 3.663, P<0.001); rs4648328_CC of DST (z = 2.850, p = 0.004), VFT (t = 3.477, p = 0.001); and rs4767944_TT of DST (z = 2.967, p = 0.003), VFT (t = 2.776, p = 0.008). The cognitive indicators of these patients significantly decreased after chemotherapy (p < 0.05). The difference in ALDH2 rs671 was most obvious.

CONCLUSION

Our results showed what kinds of ALDH2 genotyped patients that are more likely to develop CRCI. In the future, it may be possible to infer the risk of CRCI by detecting the single-nucleotide locus of ALDH2 that is conducive to strengthening clinical interventions for these patients and improving their QOL. More importantly, this study has important implications for Asian women with breast cancer as ALDH2 rs671 is a common polymorphism in Asians.

Targeted delivery of acrolein scavenger hydralazine in spinal cord injury using folate-linker-drug conjugation

Oxidative stress has been shown to play a critical pathogenic role in functional loss after spinal cord injury (SCI). As a direct result of oxidative stress, lipid peroxidation-derived aldehydes have emerged as key culprits that sustain secondary injury and contribute significantly to pathological outcomes. Acrolein, a neurotoxin, has been shown to be elevated in SCI and can result in post-SCI neurological deficits. Reducing acrolein has therefore emerged as a novel and effective therapeutic strategy in SCI. Previous studies have revealed that hydralazine, an FDA approved blood pressure lowering medication, when administered after SCI shows strong acrolein scavenging capabilities and significantly improves cellular and behavioral outcomes. However, while effective at scavenging acrolein, hydralazine's blood pressure lowering activity can have a detrimental impact on neurotrauma patients. Here, our goal was to preserve the acrolein scavenging capability while mitigating the effect of hydralazine on blood pressure. We accomplished this using a folate-targeted delivery system to deploy hydralazine to the folate receptor positive inflammatory site of the cord injury. Using a model of rat SCI, we found that this system is effective for targeting the injury site, and that folate targeted hydralazine can scavenge acrolein without significantly impacting blood pressure.