Methoxytetrahydro-2H-pyran-2-yl)methyl benzoate inhibits spinal cord injury in the rat model via PPAR-γ/PI3K/p-Akt activation

Mechanism of Mettl14 regulating AIM2 inflammasome activation and neuronal apoptosis and pyroptosis in spinal cord injury by mediating PPARγ m6A methylation

Spinal cord injury (SCI) represents a destructive pathological and neurological state. Methyltransferase-like 14 (Mettl14)-mediated m6A modification links to spinal cord injury (SCI), and we explored its mechanism. SCI mouse models were subjected to si-Mettl14 and si-negative control treatments and mouse behavior, pathological condition and apoptosis assessments. The oxygen/glucose deprivation (OGD)-induced spinal cord neuronal cell models were processed with si-Mettl14 and si-peroxisome proliferator-activated receptor γ (PPARγ) plasmids, and pcDNA3.1-YTHDF2 or synthetic dsDNA Poly(dA: dT), followed by viability and apoptosis evaluation by MTT and flow cytometry. Levels of Mettl14, PPARγ, and YTHDF2 mRNAs and proteins, AIM2 inflammasome activation-associated and pyroptosis marker proteins, PPARγ m6A methylation and pyroptosis-related inflammatory factors were determined by RT-qPCR, Western blot, Me-RIP and ELISA, with PPARγ mRNA stability and YTHDF2-PPARγ interaction assessed. Mettl14 and PPARγ m6A modification levels rose in SCI spinal cord tissues, while PPARγ levels dropped. Mettl14 knockdown dampened m6A modification, up-regulated PPARγ levels, weakened neuronal apoptosis, and ameliorated SCI in mice. OGD down-regulated PPARγ and accelerated OGD-induced neuronal apoptosis and pyroptosis via inducing Mettl14-mediated m6A modification. Mettl14 amplified PPARγ mRNA degradation and down-regulated PPARγ by mediating m6A methylation via the YTHDF2-dependent pathway. Mettl14 silencing-mediated PPARγ m6A methylation mitigated OGD-induced neuronal apoptosis and pyroptosis by inactivating AIM2 inflammasome. Mettl14 triggered activated AIM2 inflammasomes, promoted neuronal apoptosis and pyroptosis, and worsened SCI in SCI mice via mediating PPARγ m6A methylation. Mettl14 regulates AIM2 inflammasome activation, and redounds to spinal cord neuronal apoptosis and pyroptosis in SCI by mediating m6A methylation of PPARγ.

Constructing and Validating a Network of Potential Olfactory Sheathing Cell Transplants Regulating Spinal Cord Injury Progression

The pathology of spinal cord injury (SCI), including primary and secondary injuries, primarily involves hemorrhage, ischemia, edema, and inflammatory responses. Cell transplantation has been the most promising treatment for SCI in recent years; however, its specific molecular mechanism remains unclear. In this study, bioinformatics analysis verified by experiment was used to elucidate the hub genes associated with SCI and to discover the underlying molecular mechanisms of cell intervention. GSE46988 data were downloaded from the Gene Expression Omnibus dataset. In our study, differentially expressed genes (DEGs) were reanalyzed using the "R" software (R v4.2.1). Functional enrichment and protein-protein interaction network analyses were performed, and key modules and hub genes were identified. Network construction was performed for the hub genes and their associated miRNAs. Finally, a semi-quantitative analysis of hub genes and pathways was performed using quantitative real-time polymerase chain reaction. In total, 718 DEGs were identified, mainly enriched in immune and inflammation-related functions. We found that Cd4, Tp53, Rac2, and Akt3 differed between vehicle and transplanted groups, suggesting that these genes may play an essential role in the transplantation of olfactory ensheathing cells, while a toll-like receptor signaling pathway was significantly enriched in Gene set enrichment analysis, and then, the differences were statistically significant by experimentally verifying the expression of their associated molecules (Tlr4, Nf-κb, Ikkβ, Cxcl2, and Tnf-α). In addition, we searched for upstream regulatory molecules of these four central genes and constructed a regulatory network. This study is the first to construct a regulatory network for olfactory ensheathing cell transplantation in treating SCI, providing a new idea for SCI cell therapy.

Effect of Sirtuin-1 and Wnt/β-Catenin Signaling Pathway in Rat Model of Spinal Cord Injury

Sirtuin-1 (SIRT1) has anti-inflammatory and antioxidant effects and has been reported to be involved in spinal cord injury (SCI). Wnt/β-catenin signal has been shown to play a critical role in the pathogenesis of chronic diseases, and it participated in the recovery of nerve function after SCI. However, the specific link between them in SCI is unclear. In addition, targeting posttraumatic astrocyte apoptosis is crucial for improving neural degeneration and locomotor function. Therefore, in this article, we studied the relationship of β-catenin and SIRT1 using in the SCI rat model and primary astrocyte treated with hydrogen peroxide (H2O2) or lithium chloride (LiCl). Results showed that after SCI, SCI area and motor function recover over time, and β-catenin is gradually increased to the seventh day and then in turn decreases until 4 weeks, positively correlated with cell apoptosis. The expression of SIRT1 and downstream FOXO4 gradually increased, and β-catenin is negatively correlated with SIRT1 expression. Moreover, treatment with H2O2 in primary cultured astrocyte significantly increased β-catenin and Caspase-3 expression, while decreased SIRT1 and Forkhead box O- (FOXO-) 4. The immunofluorescence results are consistent with this. Administration of LiCl further aggravates the above results. These findings suggest that SIRT1 is negatively correlated with β-catenin in SCI, which promotes the apoptosis of motor neuron cells, which may be related to the participation of FOXO4.

PPARα agonist relieves spinal cord injury in rats by activating Nrf2/HO-1 via the Raf-1/MEK/ERK pathway

Objective: To observe the inhibitory effects of the peroxisome proliferator-activated receptor alpha (PPARα) agonist palmitoylethanolamide (PEA) on inflammatory responses and oxidative stress injury in rats with spinal cord injury (SCI).

Methods: The SCI rat model was established using modified Allen's method and the changes in rats’ joint motion were observed by Basso, Beattie and Bresnahan locomotor rating scale (BBB scale) at 1, 3 and 7 days after modeling, HE Staining and Nissl Staining has been carried out to evaluate the pathological lesion of spinal cords in rats. Besides, Immunohistochemical (IHC) was performed to detect the reactive oxygen species (ROS), expression levels of acrylamide (ACR) and manganese superoxide dismutase (MnSOD) in rat spinal cords, and Western Blotting was applied to measure protein expression levels of nuclear factor-kappa B (NF-κB), B cell lymphoma-2 (Bcl-2), BCL-2 associated X (BAX), phosphoinositide 3-kinase (PI3K), protein kinase B (Akt), phosphorylated (p)-Akt, HO-1, Nrf2, trithorax-1 (TRX-1), Raf-1, MEK, ERK, p-MEK and p-ERK.

Results: The PPARα agonist PEA could alleviate SCI in rats, inhibit inflammatory responses, mitigate oxidative stress injury, reduce the apoptotic rate and promote SCI rats motor function recovery. In addition, the PPARα agonist PEA was able to activate the phosphorylation of MEK and ERK, stimulate Nrf-2 translocation into the nucleus and up-regulate the expressions of HO-1 and TRX-1.

Conclusion: PPARα agonist PEA can relieve SCI in rats by inhibiting inflammatory responses and oxidative stress, which may involve a mechanism associated with the activation of Nrf2/HO-1 via the Raf-1/MEK/ERK pathway.

The antidiabetic drug troglitazone protects against PrP (106‑126)‑induced neurotoxicity via the PPARγ‑autophagy pathway in neuronal cells

Prion diseases, which involve the alteration of cellular prion protein into a misfolded isoform, disrupt the central nervous systems of humans and animals alike. Prior research has suggested that peroxisome proliferator-activator receptor (PPAR)γ and autophagy provide some protection against neurodegeneration. PPARs are critical to lipid metabolism regulation and autophagy is one of the main cellular mechanisms by which cell function and homeostasis is maintained. The present study examined the effect of troglitazone, a PPARγ agonist, on autophagy flux in a prion peptide (PrP) (106–126)-mediated neurodegeneration model. Western blot analysis confirmed that treatment with troglitazone increased LC3-II and p62 protein expression, whereas an excessive increase in autophagosomes was verified by transmission electron microscopy. Troglitazone weakened PrP (106–126)-mediated neurotoxicity via PPARγ activation and autophagy flux inhibition. A PPARγ antagonist blocked PPARγ activation as well as the neuroprotective effects induced by troglitazone treatment, indicating that PPARγ deactivation impaired troglitazone-mediated protective effects. In conclusion, the present study demonstrated that troglitazone protected primary neuronal cells against PrP (106–126)-induced neuronal cell death by inhibiting autophagic flux and activating PPARγ signals. These results suggested that troglitazone may be a useful therapeutic agent for the treatment of neurodegenerative disorders and prion diseases.