Mitigation of Microglia-mediated Acute Neuroinflammation and Tissue Damage by Heme Oxygenase 1 in a Rat Spinal Cord Injury Model

Biochanin A attenuates spinal cord injury in rats during early stages by inhibiting oxidative stress and inflammasome activation

JOURNAL/nrgr/04.03/01300535-202409000-00038/figure1/v/2024-01-16T170235Z/r/image-tiff Previous studies have shown that Biochanin A, a flavonoid compound with estrogenic effects, can serve as a neuroprotective agent in the context of cerebral ischemia/reperfusion injury; however, its effect on spinal cord injury is still unclear. In this study, a rat model of spinal cord injury was established using the heavy object impact method, and the rats were then treated with Biochanin A (40 mg/kg) via intraperitoneal injection for 14 consecutive days. The results showed that Biochanin A effectively alleviated spinal cord neuronal injury and spinal cord tissue injury, reduced inflammation and oxidative stress in spinal cord neurons, and reduced apoptosis and pyroptosis. In addition, Biochanin A inhibited the expression of inflammasome-related proteins (ASC, NLRP3, and GSDMD) and the Toll-like receptor 4/nuclear factor-κB pathway, activated the Nrf2/heme oxygenase 1 signaling pathway, and increased the expression of the autophagy markers LC3 II, Beclin-1, and P62. Moreover, the therapeutic effects of Biochanin A on early post-spinal cord injury were similar to those of methylprednisolone. These findings suggest that Biochanin A protected neurons in the injured spinal cord through the Toll-like receptor 4/nuclear factor κB and Nrf2/heme oxygenase 1 signaling pathways. These findings suggest that Biochanin A can alleviate post-spinal cord injury at an early stage.

Metformin alleviates spinal cord injury by inhibiting nerve cell ferroptosis through upregulation of heme oxygenase-1 expression

JOURNAL/nrgr/04.03/01300535-202409000-00037/figure1/v/2024-01-16T170235Z/r/image-tiff Previous studies have reported upregulation of heme oxygenase-1 in different central nervous system injury models. Heme oxygenase-1 plays a critical anti-inflammatory role and is essential for regulating cellular redox homeostasis. Metformin is a classic drug used to treat type 2 diabetes that can inhibit ferroptosis. Previous studies have shown that, when used to treat cardiovascular and digestive system diseases, metformin can also upregulate heme oxygenase-1 expression. Therefore, we hypothesized that heme oxygenase-1 plays a significant role in mediating the beneficial effects of metformin on neuronal ferroptosis after spinal cord injury. To test this, we first performed a bioinformatics analysis based on the GEO database and found that heme oxygenase-1 was upregulated in the lesion of rats with spinal cord injury. Next, we confirmed this finding in a rat model of T9 spinal cord compression injury that exhibited spinal cord nerve cell ferroptosis. Continuous intraperitoneal injection of metformin for 14 days was found to both upregulate heme oxygenase-1 expression and reduce neuronal ferroptosis in rats with spinal cord injury. Subsequently, we used a lentivirus vector to knock down heme oxygenase-1 expression in the spinal cord, and found that this significantly reduced the effect of metformin on ferroptosis after spinal cord injury. Taken together, these findings suggest that metformin inhibits neuronal ferroptosis after spinal cord injury, and that this effect is partially dependent on upregulation of heme oxygenase-1.

Promotion of 14-3-3ζ/Heme Oxygenase-1 Axis on Endotoxin-Induced Uveitis and Microglia Ferroptosis in Mice

PURPOSE

Uveitis is a common, sight-threatening inflammatory ocular disease and is the main cause of blindness, which is caused by autoimmune response, infection, and injury. The contribution of 14-3-3ζ in uveitis remains obscure. This study aims to investigate the role of 14-3-3ζ in regulating ferroptosis in retinal inflammation and its contribution to uveitis.

METHODS

A lipopolysaccharide (LPS)-induced uveitis mouse model and BV-2 cell line were used to examine the effect of LPS stimulation on the expression of 14-3-3ζ and ferroptosis in microglia. The expression of heme oxygenase-1 (HO-1) was also analyzed to understand its role in promoting microglial ferroptosis.

RESULTS

We found that LPS stimulation increased the expression of 14-3-3ζ and promoted ferroptosis in microglia. Additionally, 14-3-3ζ was found to promote microglial ferroptosis by stabilizing the expression of HO-1. These findings suggest that the 14-3-3ζ/HO-1 axis plays a crucial role in promoting microglial ferroptosis in retinal inflammation.

CONCLUSION

The study provides valuable insights into the mechanisms underlying uveitis and highlights the potential of the 14-3-3ζ/HO-1 axis as a therapeutic target for the disease. Further research in this area could lead to the development of preventive and therapeutic strategies for uveitis.

USP7 regulates HMOX-1 via deubiquitination to suppress ferroptosis and ameliorate spinal cord injury in rats

Heme oxygenase 1 (HMOX-1) is overexpressed in spinal cord injury (SCI) and relevant to ferroptosis. Ubiquitin-specific-processing protease 7 (USP7) has unveiled its role in regulating HMOX-1 stabilization while its function in SCI remains unknown. This study is to explore the potential molecular mechanism of the USP7-HMOX-1 axis in ferroptosis in a SCI rat model. SCI was assessed with Basso, Beattie, Bresnahan locomotion evaluation, hematoxylin-eosin histological staining, and immunofluorescence detection of NeuN. Ferroptosis was assessed by detections of the iron content, malondialdehyde and glutathione levels, mitochondrial damage, and glutathione peroxidase 4, 4-hydroxynonenal, USP7, and HMOX-1 expression in spinal cord. Co-immunoprecipitation was used to detect the binding of USP7 to HMOX-1. The ubiquitination level of HMOX-1 was measured after USP7 overexpression. USP7 expression was downregulated and HMOX-1 expression was upregulated in SCI rat models. HMOX-1 or USP7 overexpression promoted motor function recovery, ameliorated spinal cord damage, increased NeuN expression, and blocked the occurrence of ferroptosis in SCI rat models. In SCI rats, USP7 directly bound to HMOX-1 and its overexpression promoted HMOX-1 expression via deubiquitination. To sum up, USP7 overexpression facilitated the expression of HMOX-1 through deubiquitination, thereby reducing ferroptosis and alleviating SCI.

Promising Advances in Pharmacotherapy for Patients with Spinal Cord Injury-A Review of Studies Performed In Vivo with Modern Drugs

Spinal cord injury (SCI) is a pathological neurological condition that leads to significant motor dysfunction. It is a condition that occurs as a result of tragic accidents, violent acts, or as a consequence of chronic diseases or degenerative changes. The current treatments for patients with SCI have moderate efficacy. They improve the quality of life of patients, but they are still doomed to long-term disability. In response to the modern directions of research on possible therapeutic methods that allow for the recovery of patients with SCI, a scientific review publication is needed to summarize the recent developments in this topic. The following review is focused on the available pharmacological treatments for SCIs and the problems that patients face depending on the location of the injury. In the following review, the research team describes problems related to spasticity and neuropathic pain; possible therapeutic pathways are also described for neuroprotection and the improvement of neurotransmission within the injured spinal cord, and the review focuses on issues related to oxidative stress.

4-Ethylguaiacol modulates neuroinflammation and Th1/Th17 differentiation to ameliorate disease severity in experimental autoimmune encephalomyelitis

BACKGROUND

Multiple sclerosis (MS) is a progressive autoimmune disease characterized by the accumulation of pathogenic inflammatory immune cells in the central nervous system (CNS) that subsequently causes focal inflammation, demyelination, axonal injury, and neuronal damage. Experimental autoimmune encephalomyelitis (EAE) is a well-established murine model that mimics the key features of MS. Presently, the dietary consumption of foods rich in phenols has been reported to offer numerous health benefits, including anti-inflammatory activity. One such compound, 4-ethylguaiacol (4-EG), found in various foods, is known to attenuate inflammatory immune responses. However, whether 4-EG exerts anti-inflammatory effects on modulating the CNS inflammatory immune responses remains unknown. Thus, in this study, we assessed the therapeutic effect of 4-EG in EAE using both chronic and relapsing-remitting animal models and investigated the immunomodulatory effects of 4-EG on neuroinflammation and Th1/Th17 differentiation in EAE.

METHODS

Chronic C57BL/6 EAE and relapsing-remitting SJL/J EAE were induced followed by 4-EG treatment. The effects of 4-EG on disease progression, peripheral Th1/Th17 differentiation, CNS Th1/Th17 infiltration, microglia (MG) activation, and blood-brain barrier (BBB) disruption in EAE were evaluated. In addition, the expression of MMP9, MMP3, HO-1, and Nrf2 was assessed in the CNS of C57BL/6 EAE mice.

RESULTS

Our results showed that 4-EG not only ameliorated disease severity in C57BL/6 chronic EAE but also mitigated disease progression in SJL/J relapsing-remitting EAE. Further investigations of the cellular and molecular mechanisms revealed that 4-EG suppressed MG activation, mitigated BBB disruption, repressed MMP3/MMP9 production, and inhibited Th1 and Th17 infiltration in the CNS of EAE. Furthermore, 4-EG suppressed Th1 and Th17 differentiation in the periphery of EAE and in vitro Th1 and Th17 cultures. Finally, we found 4-EG induced HO-1 expression in the CNS of EAE in vivo as well as in MG, BV2 cells, and macrophages in vitro.

CONCLUSIONS

Our work demonstrates that 4-EG confers protection against autoimmune disease EAE through modulating neuroinflammation and inhibiting Th1 and Th17 differentiation, suggesting 4-EG, a natural compound, could be potentially developed as a therapeutic agent for the treatment of MS/EAE.