A novel ceruloplasmin mutation identified in a Chinese patient and clinical spectrum of aceruloplasminemia patients

Absence of astrocytic ceruloplasmin reverses the senescence process with aging of learning and memory abilities

Ceruloplasmin (CP) is a multi-copper ferroxidase mainly synthesized by liver, secreted into the peripheral blood, playing a critical role in regulating the iron homeostasis. In the central nervous system (CNS), the CP expressed by astrocytes plays an important role in the transportation of iron from the blood across the blood-brain barrier (BBB) into the brain. Our previous study showed that conditional knockout of astrocytic CP with Cre-LoxP system (CpGfapcKO) not only improved the learning and memory abilities of elderly mice, but also impaired the learning and memory abilities of young mice. In order to further investigate the effects of CP on learning and memory with aging, we constructed mice model with tamoxifen-induced astrocyte specific knockout of CP, induced CP knockout at 12 months old, and observed the effects on mouse learning and memory at 18 months old. We were delighted to found that ablation of astrocytic CP by tamoxifen at 12 months old could similarly enhance the learning, memory and recognition abilities in 18-month-old mice. Iron deposition in the hippocampus associated with aging was mitigated, leading to a reduction in oxidative stress. The MAPK/JNK pathway exhibited attenuation, while the PI3K/Akt/GSK3 pathway showed enhancement. This combination is expected to result in the reduction of the phosphorylation level of MYC and the elevation of the nuclear translocation of MYC, which might then contribute to reduced cellular senescence. Additionally, the ROS/MAPK/Erk and ROS/MAPK/p38 pathways-dependent cell apoptosis in hippocampus was diminished. The hallmarks of Alzheimer's Disease (AD) were all significantly reduced. Ultimately, the alleviated cellular senescence along with the reduction in AD-related markers, coincided with an improvement in learning, memory, and recognition abilities. These findings further elucidated the role of CP in brain iron metabolism, offering a novel target and strategy for the prevention and treatment of neurodegenerative diseases, such as AD associated with aging.

Iron chelators: as therapeutic agents in diseases

The concentration of iron is tightly regulated, making it an essential element. Various cellular processes in the body rely on iron, such as oxygen sensing, oxygen transport, electron transfer, and DNA synthesis. Iron excess can be toxic because it participates in redox reactions that catalyze the production of reactive oxygen species and elevate oxidative stress. Iron chelators are chemically diverse; they can coordinate six ligands in an octagonal sequence. Because of the ability of chelators to trap essential metals, including iron, they may be involved in diseases caused by oxidative stress, such as infectious diseases, cardiovascular diseases, neurodegenerative diseases, and cancer. Iron-chelating agents, by tightly binding to iron, prohibit it from functioning as a catalyst in redox reactions and transfer iron and excrete it from the body. Thus, the use of iron chelators as therapeutic agents has received increasing attention. This review investigates the function of various iron chelators in treating iron overload in different clinical conditions.

The divergent effects of astrocyte ceruloplasmin on learning and memory function in young and old mice

Ceruloplasmin (CP) plays an important role in maintaining iron homeostasis. Cp gene knockout (Cp^-/-) mice develop a neurodegenerative disease with aging and show iron accumulation in the brain. However, iron deficiency has also been observed in 3 M Cp^-/- mice. The use of systemic Cp gene knockout is insufficient to reveal specific functions for CP in the central nervous system. Considering recent discoveries that astrocytes synthetize the majority of brain CP, we generated astrocyte conditional Cp knockout (Cp^GfapcKO) mice, and found that iron contents decreased in the cerebral cortex and hippocampus of young (6 M) and old (18 M) Cp^GfapcKO mice. Further experiments revealed that 6 M Cp^GfapcKO mice exhibited impaired learning and memory function, while 18 M Cp^GfapcKO mice exhibited improved learning and memory function. Our study demonstrates that astrocytic Cp deletion blocks brain iron influx through the blood-brain-barrier, with concomitantly increased iron levels in brain microvascular endothelial cells, resulting in brain iron deficiency and down-regulation of ferritin levels in neurons, astrocytes, microglia and oligodendrocytes. At the young age, the synapse density, synapse-related protein levels, 5-hydroxytryptamine and norepinephrine, hippocampal neurogenesis and myelin formation were all decreased in Cp^GfapcKO mice. These changes affected learning and memory impairment in young Cp^GfapcKO mice. In old Cp^GfapcKO mice, iron accumulation with aging was attenuated, and was accompanied by the alleviation of the ROS-MAPK-apoptosis pathway, Tau phosphorylation and β-amyloid aggregation, thus delaying age-related memory decline. Overall, our results demonstrate that astrocytic Cp deletion has divergent effects on learning and memory function via different regulatory mechanisms induced by decreased iron contents in the brain of mice, which may present strategies for the prevention and treatment of dementia.

Aceruloplasminemia presenting with microcytic anemia in a Turkish boy due to a novel pathogenic variant

Aceruloplasminemia inherited autosomal recessively in the ceruloplasmin gene is a progressive disease with iron accumulation in various organs such as the brain, liver, pancreas, and retina. Ceruloplasmin gene encodes ceruloplasmin protein, which has ferroxidase activity and is involved in copper and iron metabolism. Progressive neurotoxicity, retinopathy, and diabetes may develop in about 40-60 decades. In addition, microcytic anemia accompanied by high ferritin and low ceruloplasmin level that develop at earlier ages can be first manifestation. Iron chelation may be utilized in the treatment to reduce the toxicity. Early diagnosis and treatment may delay the onset of symptoms. A 14-year-old male patient was followed up with microcytic anemia since an eight-years old. Anemia was accompanied by microcytosis, high ferritin, and low copper and ceruloplasmin levels. A novel homozygous c.690delG variant was detected in ceruloplasmin by whole exome sequencing. Clinical, laboratory and imaging findings of the patient demonstrated aceruloplasminemia. We present a boy with persistent microcytic anemia of the first manifestation at the age of eight, as the youngest case of aceruloplasminemia in the literature. Thereby, aceruloplasminemia should be kept in mind in the etiology of microcytic anemia whose cause couldn't found in childhood.

Cerebral Iron Deposition in Neurodegeneration

Disruption of cerebral iron regulation appears to have a role in aging and in the pathogenesis of various neurodegenerative disorders. Possible unfavorable impacts of iron accumulation include reactive oxygen species generation, induction of ferroptosis, and acceleration of inflammatory changes. Whole-brain iron-sensitive magnetic resonance imaging (MRI) techniques allow the examination of macroscopic patterns of brain iron deposits in vivo, while modern analytical methods ex vivo enable the determination of metal-specific content inside individual cell-types, sometimes also within specific cellular compartments. The present review summarizes the whole brain, cellular, and subcellular patterns of iron accumulation in neurodegenerative diseases of genetic and sporadic origin. We also provide an update on mechanisms, biomarkers, and effects of brain iron accumulation in these disorders, focusing on recent publications. In Parkinson’s disease, Friedreich’s disease, and several disorders within the neurodegeneration with brain iron accumulation group, there is a focal siderosis, typically in regions with the most pronounced neuropathological changes. The second group of disorders including multiple sclerosis, Alzheimer’s disease, and amyotrophic lateral sclerosis shows iron accumulation in the globus pallidus, caudate, and putamen, and in specific cortical regions. Yet, other disorders such as aceruloplasminemia, neuroferritinopathy, or Wilson disease manifest with diffuse iron accumulation in the deep gray matter in a pattern comparable to or even more extensive than that observed during normal aging. On the microscopic level, brain iron deposits are present mostly in dystrophic microglia variably accompanied by iron-laden macrophages and in astrocytes, implicating a role of inflammatory changes and blood–brain barrier disturbance in iron accumulation. Options and potential benefits of iron reducing strategies in neurodegeneration are discussed. Future research investigating whether genetic predispositions play a role in brain Fe accumulation is necessary. If confirmed, the prevention of further brain Fe uptake in individuals at risk may be key for preventing neurodegenerative disorders.

A New Pathogenic Missense Variant in a Consanguineous North-African Family Responsible for a Highly Variable Aceruloplasminemia Phenotype: A Case-Report

Aceruloplasminemia is a rare autosomal recessive inherited disorder. Mutations in the ceruloplasmin gene cause depressed ferroxidase activity leading to iron accumulation. The clinical phenotype is highly variable: anemia, retinopathy, diabetes mellitus, psychiatric disorders, and neurological symptoms including parkinsonian disorders and dementia are the main features of this disease. Characterized by high serum ferritin with low transferrin saturation, aceruloplasminemia uniquely combines brain, liver and systemic iron overload. We report here four new cases of aceruloplasminemia in a consanguineous North-African family. Genetic sequencing revealed a homozygous missense variant c.656T>A in exon 4 of the ceruloplasmin gene, which had been described previously as of “unknown significance” in the dbSNP database and never associated with ACP in the HGMD database. Ferroxidase activity was strongly depressed. Clinical manifestations varied among cases. The proband exhibited mild microcytic anemia, diabetes mellitus, psychosis and parkinsonism, whereas the other cases were asymptomatic or mildly anemic, although high serum ferritin and brain iron deposition were documented in all of them. Therapeutic management was complex. The proband started deferoxamine treatment when already symptomatic and he rapidly declined. In the asymptomatic cases, the treatment was associated with poor tolerance and was discontinued due to anemia requiring red blood cell transfusion. Our series illustrates the need for new therapeutic approaches to aceruloplasminemia.