Cell Death-Osis of Dopaminergic Neurons and the Role of Iron in Parkinson's Disease

Diosgenin ameliorating non-alcoholic fatty liver disease via Nrf2-mediated regulation of oxidative stress and ferroptosis

AIM

This study aimed to investigate the mechanisms through which diosgenin inhibits the pathogenesis of non-alcoholic fatty liver disease, focusing particularly on ferroptosis-related pathways and its reliance on nuclear factor erythroid 2-related factor 2.

MATERIALS AND METHODS

Using a rat model, we showed diosgenin's efficacy in reducing lipid deposition throughout the body and examined its impact on ferroptosis-related gene expression in vivo. Moreover, in vitro experiments using human hepatocellular liver carcinoma cell line cells were conducted to assess oxidative stress and ferroptosis levels.

RESULTS

Diosgenin decreased lipid accumulation and steatosis; lowered serum levels of total cholesterol, triglycerides, low-density lipoprotein cholesterol, glutamic pyruvic transaminase and glutamic oxaloacetic transaminase; reduced interleukin-1β and tumour necrosis factor-α; diosgenin decreased malondialdehyde levels; and increased serum superoxide dismutase levels in a rat model of high-fat diet-induced non-alcoholic fatty liver disease. Diosgenin upregulated the expression of nuclear factor erythroid 2-related factor 2 and its downstream ferroptosis-related genes to inhibit ferroptosis in the livers of rats with non-alcoholic fatty liver disease. Diosgenin decreased reactive oxygen species levels and enhanced the expression of ferroptosis-related genes in human hepatocellular liver carcinoma cells induced by free fatty acids, with its effects being dependent on nuclear factor erythroid 2-related factor 2.

CONCLUSIONS

This study highlights the potential of diosgenin from Dioscoreaceae plants in mitigating oxidative stress and ferroptosis levels through nuclear factor erythroid 2-related factor 2 regulation, offering novel insights into the treatment of non-alcoholic fatty liver disease and other metabolic disorders through traditional Chinese medicine.

Neuroprotective and anti-inflammatory effects of the RIPK3 inhibitor GSK872 in an MPTP-induced mouse model of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder triggered by the loss of dopaminergic neurons in the substantia nigra (SN). Recent studies have demonstrated that necroptosis is involved in dopaminergic neuronal cell death and the resulting neuroinflammation. During the process of necroptosis, a necrosome complex is formed consisting of the proteins receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like protein (MLKL). Although the neuroprotective effects of the RIPK1-specific inhibitor necrostatin-1, as well as RIPK3 and MLKL knockout in mice, have been described, the effects of RIPK3 pharmacological inhibitors have not yet been reported in animal models of PD. In the present study, we investigated the neuroprotective effects of GSK872, a specific RIPK3 inhibitor, in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. GSK872 rescued MPTP-induced motor impairment and inhibited tyrosine hydroxylase-positive dopaminergic cell death in the SN and striatum. Additionally, GSK872 inhibited the MPTP-induced increase in the expression of p-RIPK3 and p-MLKL in both the dopaminergic neurons and microglia, as assessed by biochemical and histological analyses. GSK872 further inhibited microglial activation and the expression of inflammatory mediators including NLRP3, interleukin (IL)-1β, IL-6, tumor necrosis factor-alpha, and inducible nitric oxide synthase in the SN region of MPTP mice. Using in vitro experiments, we validated the effects of GSK872 on necroptosis in SH-SY5Y neuronal and BV2 microglial cells. Overall, our results suggest that GSK872 exerts neuroprotective and anti-inflammatory effects, and may thus have therapeutic potential for PD.

Dopaminergic neuronal death via necroptosis in Parkinson's disease: A review of the literature

Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive dysfunction and loss of dopaminergic neurons of the substantia nigra pars compacta (SNc). Several pathways of programmed cell death are likely to play a role in dopaminergic neuron death, such as apoptosis, necrosis, pyroptosis and ferroptosis, as well as cell death associated with proteasomal and mitochondrial dysfunction. A better understanding of the molecular mechanisms underlying dopaminergic neuron death could inform the design of drugs that promote neuron survival. Necroptosis is a recently characterized regulated cell death mechanism that exhibits morphological features common to both apoptosis and necrosis. It requires activation of an intracellular pathway involving receptor-interacting protein 1 kinase (RIP1 kinase, RIPK1), receptor-interacting protein 3 kinase (RIP3 kinase, RIPK3) and mixed lineage kinase domain-like pseudokinase (MLKL). The potential involvement of this programmed cell death pathway in the pathogenesis of PD has been studied by analysing biomarkers for necroptosis, such as the levels and oligomerization of phosphorylated RIPK3 (pRIPK3) and phosphorylated MLKL (pMLKL), in several PD preclinical models and in PD human tissue. Although there is evidence that other types of cell death also have a role in DA neuron death, most studies support the hypothesis that this cell death mechanism is activated in PD tissues. Drugs that prevent or reduce necroptosis may provide neuroprotection for PD. In this review, we summarize the findings from these studies. We also discuss how manipulating necroptosis might open a novel therapeutic approach to reduce neuronal degeneration in PD.

Oral administration of sophoricoside (SOP) inhibits neuronal damage and neuroinflammation to curb neurodegeneration in Parkinson's disease

Neuronal apoptosis and neuroinflammation are key factors involved in the pathological changes of Parkinson's disease (PD). Sophoricoside (SOP) has shown anti-inflammatory and anti-apoptosis effects in various diseases. However, the role of SOP in PD has not been reported. In this experiment, we found that oral administration of SOP alleviated weight loss and motor symptoms in 1-Methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-injected mice. Further studies revealed that SOP inhibited inflammatory responses and neuronal apoptosis in the midbrain region of MPTP-injected mice. In vitro mechanistic study, we found that SOP exerts neuroprotective effects through a two-sided action. On the one hand, SOP inhibits Lipopolysaccharide (LPS)-induced inflammatory responses in microglia by inhibiting the Nuclear factor kappa-B(NF-κB) pathway. On the other hand, SOP inhibits 1-methyl-4-phenylpyridinium (MPP+)-induced neuronal apoptosis by regulating the Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathway. Thus SOP is expected to be a potential therapeutic agent for PD by targeting neuroinflammation and neuronal apoptosis.

Pro-Inflammatory Priming of the Brain: The Underlying Cause of Parkinson's Disease

Parkinson's disease (PD) is a multifactorial neurodegenerative pathology characterized by the progressive loss of dopaminergic neurons in the substantia nigra of the brain. Aging is considered the main risk factor for the development of idiopathic PD. However, immunity and inflammation play a crucial role in the pathogenesis of this disorder. In mice, we showed that pro-inflammatory priming of the brain sensitizes to severe PD development, regardless of animal age. Age-related sub-acute inflammation, as well as the activation of the immune response upon exposure to harmful stimuli, enhances PD manifestations. The severity of PD is influenced by the engagement of host resistance mechanisms against infection based on the removal of iron (Fe) from the circulation. The sequestration of Fe by immune cells prevents pathogens from proliferating. However, it leads to the formation of a Fe-loaded circulating compartment. When entering the brain through a compromised blood-brain barrier, Fe-loaded immune cells contribute to enhancing neuroinflammation and brain Fe overload. Thus, pro-inflammatory priming of the brain exacerbates neuronal damage and represents a risk factor for the development of severe PD symptoms. Further investigations are now required to better understand whether therapeutic interventions inhibiting this phenomenon might protect against PD.

Gut Dysbiosis: A Target for Protective Interventions against Parkinson’s Disease

Sub-chronic inflammation, caused by age-related dysbiosis, primes the brain to neuroinflammation and neurodegenerative diseases. Evidence revealed that Parkinson’s disease (PD) might originate in the gut, demonstrating gastro-intestinal disturbances, as reported by PD patients long before developing motor symptoms. In this study, we conducted comparative analyses in relatively young and old mice maintained in conventional or gnotobiotic conditions. We aimed to confirm that the effects induced by age-related dysbiosis, rather than aging itself, sensitize to PD onset. This hypothesis was confirmed in germ-free (GF) mice, which proved resistant to the pharmacological induction of PD, regardless of their age. Contrary to conventional animals, old GF mice did not develop an inflammatory phenotype or an accumulation of iron in the brain, two catalysts sensitizing to disease onset. The resistance of GF mice to PD is reverted when colonized with stool collected from conventional old animals, but not if receiving bacterial content from young mice. Hence, changes in gut microbiota composition are a risk factor for PD development and can be targeted preventively by iron chelators, shown to protect the brain from pro-inflammatory intestinal priming that sensitizes to neuroinflammation and the development of severe PD.

Screening of Differentially Expressed Iron Death-Related Genes and the Construction of Prognosis Model in Patients with Renal Clear Cell Carcinoma

Objective

In this study, we used the TCGA database and ICGC database to establish a prognostic model of iron death associated with renal cell carcinoma, which can provide predictive value for the identification of iron death-related genes and clinical treatment of renal clear cell carcinoma.

Methods

The gene expression profiles and clinical data of renal clear cell carcinoma and normal tissues were obtained in the TCGA database and ICGC database, and the differential genes related to iron death were screened out. The differential genes were screened out by single and multifactor Cox risk regression model. R software, "edge" package (version 4.0), was used to identify the DELs of 551 transcriptional gene samples and 522 clinical samples. The risk prediction model with genes was established to analyze the correlation between the genes in the established model and clinical characteristics, Through the final screening of iron death related genes, it can be used to predict the prognosis of renal clear cell carcinoma and provide advice for clinical targeted therapy.

Results

Seven iron death differential genes (CLS2, FANCD2, PHKG2, ACSL3, ATP5MC3, CISD1, PEBP1) associated with renal clear cell carcinoma were finally screened and were refer to previous relevant studies. These genes are closely related to iron death and have great value for the prognosis of renal clear cell carcinoma.

Conclusion

Seven iron death genes can accurately predict the survival of patients with renal clear cell carcinoma.