Endothelin-1-mediated vasoconstriction alters cerebral gene expression in iron homeostasis and eicosanoid metabolism

Ferroptosis in Neurological Disease

Iron accumulation in the CNS occurs in many neurological disorders. It can contribute to neuropathology as iron is a redox-active metal that can generate free radicals. The reasons for the iron buildup in these conditions are varied and depend on which aspects of iron influx, efflux, or sequestration that help maintain iron homeostasis are dysregulated. Iron was shown recently to induce cell death and damage via lipid peroxidation under conditions in which there is deficient glutathione-dependent antioxidant defense. This form of cell death is called ferroptosis. Iron chelation has had limited success in the treatment of neurological disease. There is therefore much interest in ferroptosis as it potentially offers new drugs that could be more effective in reducing iron-mediated lipid peroxidation within the lipid-rich environment of the CNS. In this review, we focus on the molecular mechanisms that induce ferroptosis. We also address how iron enters and leaves the CNS, as well as the evidence for ferroptosis in several neurological disorders. Finally, we highlight biomarkers of ferroptosis and potential therapeutic strategies.

Comparative transcriptomes reveal geographic differences in the ability of the liver of plateau zokors (Eospalax baileyi) to respond and adapt to toxic plants

BACKGROUND

Environmental changes are expected to intensify in the future. The invasion of toxic plants under environmental changes may change herbivore feeding environments. Herbivores living long-term in toxic plant-feeding environments will inevitably ingest plant secondary metabolites (PSMs), and under different feeding environments are likely to have unique protection mechanisms that support improved adaptation to PSMs in their habitat. We aimed to compare different subterranean herbivore population responses and adaptations to toxic plants to unveil their feeding challenges.

RESULTS

Here, we investigated the adaptive capacity of the liver in two geographically separated populations of plateau zokors (Eospalax baileyi) before and after exposure to the toxic plant Stellera chamaejasme (SC), at the organ, biochemical, and transcriptomic levels. The results showed no significant liver granules or inflammatory reactions in the Tianzhu (TZ) population after the SC treatment. The transaminase level in the TZ population was significantly lower than that in the Luqu population. Transcriptome analysis revealed that the TZ population exhibited interactions with other detoxification metabolic pathways by oxytocin pathway-associated genes, including diacylglycerol lipase alpha (Dagla), calcium/calmodulin dependent protein kinase II Alpha (Camk2a), and CD38 molecule (Cd38). The phase II process of liver drug metabolism increased to promote the rate of metabolism. We found that alternative splicing (AS) and the expression of the cyclin D (Ccnd1) gene interact-a TZ population hallmark-reduced liver inflammatory responses.

CONCLUSION

Our study supports the detoxification limitation hypothesis that differences in liver detoxification metabolism gene expression and AS are potential factors in herbivore adaptation to PSMs and may be a strategy of different herbivore populations to improve toxic plant adaptability.

Screening and identification of key biomarkers of depression using bioinformatics

We aimed to identify the molecular biomarkers of MDD disease progression to uncover potential mechanisms of major depressive disorder (MDD). In this study, three microarray data sets, GSE44593, GSE12654, and GSE54563, were cited from the Gene Expression Omnibus database for performance evaluation. To perform molecular functional enrichment analyses, differentially expressed genes (DEGs) were identified, and a protein-protein interaction network was configured using the Search Tool for the Retrieval of Interacting Genes/Proteins and Cytoscape. To assess multi-purpose functions and pathways, such as signal transduction, plasma membrane, protein binding, and cancer pathways, a total of 220 DEGs, including 143 upregulated and 77 downregulated genes, were selected. Additionally, six central genes were observed, including electron transport system variant transcription factor 6, FMS-related receptor tyrosine kinase 3, carnosine synthetase 1, solute carrier family 22 member 13, prostaglandin endoperoxide synthetase 2, and protein serine kinase H1, which had a significant impact on cell proliferation, extracellular exosome, protein binding, and hypoxia-inducible factor 1 signaling pathway. This study enhances our understanding of the molecular mechanism of the occurrence and progression of MDD and provides candidate targets for its diagnosis and treatment.

Immune Function of Endothelial Cells: Evolutionary Aspects, Molecular Biology and Role in Atherogenesis

Atherosclerosis is one of the key problems of modern medicine, which is due to the high prevalence of atherosclerotic cardiovascular diseases and their significant share in the structure of morbidity and mortality in many countries. Atherogenesis is a complex chain of events that proceeds over many years in the vascular wall with the participation of various cells. Endothelial cells are key participants in vascular function. They demonstrate involvement in the regulation of vascular hemodynamics, metabolism, and innate immunity, which act as leading links in the pathogenesis of atherosclerosis. These endothelial functions have close connections and deep evolutionary roots, a better understanding of which will improve the prospects of early diagnosis and effective treatment.

Dysregulation of Iron Homeostasis in the Central Nervous System and the Role of Ferroptosis in Neurodegenerative Disorders

Significance: Iron accumulation occurs in the central nervous system (CNS) in a variety of neurological conditions as diverse as spinal cord injury, stroke, multiple sclerosis, Parkinson's disease, and others. Iron is a redox-active metal that gives rise to damaging free radicals if its intracellular levels are not controlled or if it is not properly sequestered within cells. The accumulation of iron occurs due to dysregulation of mechanisms that control cellular iron homeostasis. Recent Advances: The molecular mechanisms that regulate cellular iron homeostasis have been revealed in much detail in the past three decades, and new advances continue to be made. Understanding which aspects of iron homeostasis are dysregulated in different conditions will provide insights into the causes of iron accumulation and iron-mediated tissue damage. Recent advances in iron-dependent lipid peroxidation leading to cell death, called ferroptosis, has provided useful insights that are highly relevant for the lipid-rich environment of the CNS. Critical Issues: This review examines the mechanisms that control normal cellular iron homeostasis, the dysregulation of these mechanisms in neurological disorders, and more recent work on how iron can induce tissue damage via ferroptosis. Future Directions: Quick and reliable tests are needed to determine if and when ferroptosis contributes to the pathogenesis of neurological disorders. In addition, there is need to develop better druggable agents to scavenge lipid radicals and reduce CNS damage for neurological conditions for which there are currently few effective treatments. Antioxid. Redox Signal. 37, 150-170.

Endothelin A receptor antagonist attenuated renal iron accumulation in iron overload heme oxygenase-1 knockout mice

Progressive iron accumulation and renal impairment are prominent in both patients and mouse models of sickle cell disease (SCD). Endothelin A receptor (ETA) antagonism prevents this iron accumulation phenotype and reduces renal iron deposition in proximal tubules of SCD mice. To better understand the mechanisms of iron metabolism in the kidney and the role of ETA receptor in iron chelation and transport, we studied renal iron handling in a non-sickle cell iron overload model, heme oxygenase-1 (Hmox-1-/-) knockout mice. We found that Hmox-1-/- mice had elevated plasma endothelin-1 (ET-1), cortical ET-1 mRNA expression, and renal iron content compared to Hmox-1+/+ controls. The ETA receptor antagonist, ambrisentan, attenuated renal iron deposition, without any changes to anemia status in Hmox-1-/- mice. This was accompanied by reduced urinary iron excretion. Finally, ambrisentan had an important iron recycling effect by increasing expression of cellular iron exporter, ferroportin-1 (FPN-1) and circulating total iron levels in Hmox-1-/- mice. These findings suggest the ET-1/ETA signaling pathway contributes to in renal iron trafficking in a murine model of iron overload.

Genetic Variability and Trajectories of DNA Methylation May Support a Role for HAMP in Patient Outcomes After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND/OBJECTIVE

Preclinical evidence suggests that iron homeostasis is an important biological mechanism following aneurysmal subarachnoid hemorrhage (aSAH); however, this concept is underexplored in humans. This study examined the relationship between patient outcomes following aSAH and genetic variants and DNA methylation in the hepcidin gene (HAMP), a key regulator of iron homeostasis.

METHODS

In this exploratory, longitudinal observational study, participants with verified aSAH were monitored for acute outcomes including cerebral vasospasm (CV) and delayed cerebral ischemia (DCI) and evaluated post-discharge at 3 and 12 months for long-term outcomes of death and functional status using the Modified Rankin Scale (mRS; poor = 3-6) and Glasgow Outcome Scale (GOS; poor = 1-3). Participants were genotyped for two genetic variants, and DNA methylation data were collected from serial cerebrospinal fluid over 14 days post-aSAH at eight methylation sites within HAMP. Participants were grouped based on their site-specific DNA methylation trajectory, with and without correcting for cell-type heterogeneity (CTH), and the associations between genetic variants and inferred DNA methylation trajectory groups and patient outcomes were tested. To correct for multiple testing, an empirical significance threshold was computed using permutation testing.

RESULTS

Genotype data for rs10421768 and rs7251432 were available for 241 and 371 participants, respectively, and serial DNA methylation data were available for 260 participants. Acute outcome prevalence included CV in 45% and DCI in 37.1% of the overall sample. Long-term outcome prevalence at 3 and 12 months included poor GOS in 23% and 21%, poor mRS in 31.6% and 27.3%, and mortality in 15.1% and 18.2%, respectively, in the overall sample. Being homozygous for the rs7251432 variant allele was significantly associated with death at 3 months (p = 0.003) and was the only association identified that passed adjustment for multiple testing mentioned above. Suggestive associations (defined as trending toward significance, p value < 0.05, but not meeting empirical significance thresholds) were identified between the homozygous variant allele for rs7251432 and poor GOS and mRS at 3 months (both p = 0.04) and death at 12 months (p = 0.02). For methylation trajectory groups, no associations remained significant after correction for multiple testing. However, for methylation trajectory groups not adjusted for CTH, suggestive associations were identified between cg18149657 and poor GOS and mRS at 3 months (p = 0.003 and p = 0.04, respectively) and death at 3 months (p = 0.04), and between cg26283059 and DCI (p = 0.01). For methylation trajectory groups adjusted for CTH, suggestive associations were identified between cg02131995 and good mRS at 12 months (p = 0.02), and between cg26283059 and DCI (p = 0.01).

CONCLUSIONS

This exploratory pilot study offers preliminary evidence that HAMP may play a role in patient outcomes after aSAH. Replication of this study and mechanistic investigation of the role of HAMP in patient outcomes after aSAH are needed.

Genetic Variability in the Iron Homeostasis Pathway and Patient Outcomes After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND/OBJECTIVE

Iron can be detrimental to most tissues both in excess and in deficiency. The brain in particular is highly susceptible to the consequences of excessive iron, especially during blood brain barrier disruption after injury. Preliminary evidence suggests that iron homeostasis is important during recovery after neurologic injury; therefore, the exploration of genetic variability in genes involved in iron homeostasis is an important area of patient outcomes research. The purpose of this study was to examine the relationship between tagging single nucleotide polymorphisms (SNPs) in candidate genes related to iron homeostasis and acute and long-term patient outcomes after aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

This study was a longitudinal, observational, candidate gene association study of participants with aSAH that used a two-tier design including tier 1 (discovery, n = 197) and tier 2 (replication, n = 277). Participants were followed during the acute outcome phase for development of cerebral vasospasm and delayed cerebral ischemia (DCI) and during the long-term outcome phase for death and gross functional outcome using the Glasgow Outcome Scale (GOS; poor = 1-3). Genetic association analyses were performed using a logistic regression model adjusted for age, sex, and Fisher grade. Approximate Bayes factors (ABF) and Bayesian false discovery probabilities (BFDP) were used to prioritize and interpret results.

RESULTS

In tier 1, 235 tagging SNPs in 28 candidate genes were available for analysis and 26 associations (20 unique SNPs in 12 genes) were nominated for replication in tier 2. In tier 2, we observed an increase in evidence of association for three associations in the ceruloplasmin (CP) and cubilin (CUBN) genes. We observed an association of rs17838831 (CP) with GOS at 3 months (tier 2 results, odds ratio [OR] = 2.10, 95% confidence interval [CI] = 1.14-3.86, p = 0.018, ABF = 0.52, and BFDP = 70.8%) and GOS at 12 months (tier 2 results, OR = 1.86, 95% CI 0.98-3.52, p = 0.058, ABF = 0.72, and BFDP = 77.3%) as well as rs10904850 (CUBN) with DCI (tier 2 results, OR = 0.70, 95% CI 0.48-1.02, p = 0.064, ABF = 0.59, and BFDP = 71.8%).

CONCLUSIONS

Among the genes examined, our findings support a role for CP and CUBN in patient outcomes after aSAH. In an effort to translate these findings into clinical utility and improve outcomes after aSAH, additional research is needed to examine the functional roles of these genes after aSAH.

Nrf2 protects against seawater drowning-induced acute lung injury via inhibiting ferroptosis

Background

Ferroptosis is a new type of nonapoptotic cell death model that was closely related to reactive oxygen species (ROS) accumulation. Seawater drowning-induced acute lung injury (ALI) which is caused by severe oxidative stress injury, has been a major cause of accidental death worldwide. The latest evidences indicate nuclear factor (erythroid-derived 2)-like 2 (Nrf2) suppress ferroptosis and maintain cellular redox balance. Here, we test the hypothesis that activation of Nrf2 pathway attenuates seawater drowning-induced ALI via inhibiting ferroptosis.

Methods

we performed studies using Nrf2-specific agonist (dimethyl fumarate), Nrf2 inhibitor (ML385), Nrf2-knockout mice and ferroptosis inhibitor (Ferrostatin-1) to investigate the potential roles of Nrf2 on seawater drowning-induced ALI and the underlying mechanisms.

Results

Our data shows that Nrf2 activator dimethyl fumarate could increase cell viability, reduced the levels of intracellular ROS and lipid ROS, prevented glutathione depletion and lipid peroxide accumulation, increased FTH1 and GPX4 mRNA expression, and maintained mitochondrial membrane potential in MLE-12 cells. However, ML385 promoted cell death and lipid ROS production in MLE-12 cells. Furthermore, the lung injury became more aggravated in the Nrf2-knockout mice than that in WT mice after seawater drowning.

Conclusions

These results suggested that Nrf2 can inhibit ferroptosis and therefore alleviate ALI induced by seawater drowning. The effectiveness of ferroptosis inhibition by Nrf2 provides a novel therapeutic target for seawater drowning-induced ALI.

Deciphering the Iron Side of Stroke: Neurodegeneration at the Crossroads Between Iron Dyshomeostasis, Excitotoxicity, and Ferroptosis

In general, iron represents a double-edged sword in metabolism in most tissues, especially in the brain. Although the high metabolic demands of brain cells require iron as a redox-active metal for ATP-producing enzymes, the brain is highly vulnerable to the devastating consequences of excessive iron-induced oxidative stress and, as recently found, to ferroptosis as well. The blood-brain barrier (BBB) protects the brain from fluctuations in systemic iron. Under pathological conditions, especially in acute brain pathologies such as stroke, the BBB is disrupted, and iron pools from the blood gain sudden access to the brain parenchyma, which is crucial in mediating stroke-induced neurodegeneration. Each brain cell type reacts with changes in their expression of proteins involved in iron uptake, efflux, storage, and mobilization to preserve its internal iron homeostasis, with specific organelles such as mitochondria showing specialized responses. However, during ischemia, neurons are challenged with excess extracellular glutamate in the presence of high levels of extracellular iron; this causes glutamate receptor overactivation that boosts neuronal iron uptake and a subsequent overproduction of membrane peroxides. This glutamate-driven neuronal death can be attenuated by iron-chelating compounds or free radical scavenger molecules. Moreover, vascular wall rupture in hemorrhagic stroke results in the accumulation and lysis of iron-rich red blood cells at the brain parenchyma and the subsequent presence of hemoglobin and heme iron at the extracellular milieu, thereby contributing to iron-induced lipid peroxidation and cell death. This review summarizes recent progresses made in understanding the ferroptosis component underlying both ischemic and hemorrhagic stroke subtypes.

Brain iron overload following intracranial haemorrhage

Intracranial haemorrhages, including intracerebral haemorrhage (ICH), intraventricular haemorrhage (IVH) and subarachnoid haemorrhage (SAH), are leading causes of morbidity and mortality worldwide. In addition, haemorrhage contributes to tissue damage in traumatic brain injury (TBI). To date, efforts to treat the long-term consequences of cerebral haemorrhage have been unsatisfactory. Incident rates and mortality have not showed significant improvement in recent years. In terms of secondary damage following haemorrhage, it is becoming increasingly apparent that blood components are of integral importance, with haemoglobin-derived iron playing a major role. However, the damage caused by iron is complex and varied, and therefore, increased investigation into the mechanisms by which iron causes brain injury is required. As ICH, IVH, SAH and TBI are related, this review will discuss the role of iron in each, so that similarities in injury pathologies can be more easily identified. It summarises important components of normal brain iron homeostasis and analyses the existing evidence on iron-related brain injury mechanisms. It further discusses treatment options of particular promise.

Mexico City normal weight children exposed to high concentrations of ambient PM2.5 show high blood leptin and endothelin-1, vitamin D deficiency, and food reward hormone dysregulation versus low pollution controls. Relevance for obesity and Alzheimer disease

Millions of Mexico, US and across the world children are overweight and obese. Exposure to fossil-fuel combustion sources increases the risk for obesity and diabetes, while long-term exposure to fine particulate matter (PM2.5) and ozone (O3) above US EPA standards is associated with increased risk of Alzheimer's disease (AD). Mexico City Metropolitan Area children are chronically exposed to PM2.5 and O3 concentrations above the standards and exhibit systemic, brain and intrathecal inflammation, cognitive deficits, and Alzheimer disease neuropathology. We investigated adipokines, food reward hormones, endothelial dysfunction, vitamin D and apolipoprotein E (APOE) relationships in 80 healthy, normal weight 11.1±3.2 year olds matched by age, gender, BMI and SES, low (n: 26) versus high (n:54) PM2.5 exposures. Mexico City children had higher leptin and endothelin-1 (p<0.01 and p<0.000), and decreases in glucagon-like peptide-1 (GLP 1), ghrelin, and glucagon (<0.02) versus controls. BMI and leptin relationships were significantly different in low versus high PM2.5 exposed children. Mexico City APOE 4 versus 3 children had higher glucose (p=0.009). Serum 25-hydroxyvitamin D<30 ng/mL was documented in 87% of Mexico City children. Leptin is strongly positively associated to PM 2.5 cumulative exposures. Residing in a high PM2.5 and O3 environment is associated with 12h fasting hyperleptinemia, altered appetite-regulating peptides, vitamin D deficiency, and increases in ET-1 in clinically healthy children. These changes could signal the future trajectory of urban children towards the development of insulin resistance, obesity, type II diabetes, premature cardiovascular disease, addiction-like behavior, cognitive impairment and Alzheimer's disease. Increased efforts should be made to decrease pediatric PM2.5 exposures, to deliver health interventions prior to the development of obesity and to identify and mitigate environmental factors influencing obesity and Alzheimer disease.