Lipid dysmetabolism in ceruloplasmin-deficient mice revealed both in vivo and ex vivo by MRI, MRS and NMR analyses

Ceruloplasmin (Cp) is a ferroxidase that plays a role in cellular iron homeostasis and is mainly expressed in the liver and secreted into the blood. Cp is also produced by adipose tissue, which releases it as an adipokine. Although a dysfunctional interaction of iron with the metabolism of lipids has been associated with several metabolic diseases, the role of Cp in adipose tissue metabolism and in the interplay between hepatocytes and adipocytes has been poorly investigated. We previously found that Cp-deficient (CpKO) mice become overweight and demonstrate adipose tissue accumulation together with liver steatosis during aging, suggestive of lipid dysmetabolism. In the present study, we investigated the lipid alterations which occur during aging in adipose tissue and liver of CpKO and wild-type mice both in vivo and ex vivo. During aging of CpKO mice, we observed adipose tissue accumulation and liver lipid deposition, both of which are associated with macrophage infiltration. Liver lipid deposition was characterized by accumulation of triglycerides, fatty acids and ω-3 fatty acids, as well as by a switch from unsaturated to saturated fatty acids, which is characteristic of lipid storage. Liver steatosis was preceded by iron deposition and macrophage infiltration, and this was observed to be already occurring in younger CpKO mice. The accumulation of ω-3 fatty acids, which can only be acquired through diet, was associated with body weight increase in CpKO mice despite food intake being equal to that of wild-type mice, thus underlining the alterations in lipid metabolism/catabolism in Cp-deficient animals.

ASYMPTOMATIC OCULAR MANIFESTATIONS OF ACERULOPLASMINEMIA IN TWO ADULT WHITE SIBLINGS: A MULTIMODAL IMAGING APPROACH

PURPOSE

To report ocular manifestations of aceruloplasminemia in two adult White siblings.

METHODS

The ocular findings were investigated using a multimodal imaging approach including color fundus photography, fluorescein angiography, autofluorescence imaging, and spectral-domain optical coherence tomography.

RESULTS

A 43-year-old woman and a 39-year-old man were diagnosed with aceruloplasminemia based on clinical symptoms, laboratory tests, liver biopsy, and genetic examination of the ceruloplasmin gene confirming the homozygotic mutation G708S. Both patients had no ophthalmologic symptoms, unremarkable anterior segment, and visual acuity of 20/20 in both eyes. Indirect ophthalmoscopy of the fundus revealed subtle yellowish color with punctate inhomogeneous pigmentation in the whole retina. The autofluorescence images demonstrated remarkable punctate hyperfluorescence involving the central and peripheral retina. Spectral-domain optical coherence tomography images showed normal retinal structure in the macular area with intact outer retinal layers. Fluorescein angiography showed a slightly inhomogeneous pattern of hypofluorescence and hyperfluorescence from the early until late angiography phase.

CONCLUSION

We describe two adult cases of ocular manifestations of a rare hereditary condition with systemic iron overload. Retinal degeneration in aceruloplasminemia might be overlooked on a routine ophthalmic examination and requires at least an autofluorescence image because initial damage at the level of retinal pigment epithelium is not always visible on ophthalmoscopy.

Ceruloplasmin-Deficient Mice Show Dysregulation of Lipid Metabolism in Liver and Adipose Tissue Reduced by a Protein Replacement

Ceruloplasmin is a ferroxidase that plays a role in iron homeostasis; its deficiency fosters inter alia iron accumulation in the liver, which expresses the soluble form of the protein secreted into the bloodstream. Ceruloplasmin is also secreted by the adipose tissue, but its role in adipocytes has been poorly investigated. We hypothesized that ceruloplasmin might have a role in iron/lipid interplay. We investigated iron/lipid dysmetabolism in the liver and adipose tissue of the ceruloplasmin-deficient mouse (CpKO) model of aceruloplasminemia and evaluated the effectiveness of ceruloplasmin replacement. We found that CpKO mice were overweight, showing adipose tissue accumulation, liver iron deposition and steatosis. In the adipose tissue of CpKO mice, iron homeostasis was not altered. Conversely, the levels of adiponectin and leptin adipokines behaved opposite to the wild-type. Increased macrophage infiltration was observed in adipose tissue and liver of CpKO mice, indicating tissue inflammation. The treatment of CpKO mice with ceruloplasmin limited liver iron accumulation and steatosis without normalizing the expression of iron homeostasis-related proteins. In the CpKO mice, the protein replacement limited macrophage infiltration in both adipose and hepatic tissues reduced the level of serum triglycerides, and partially recovered adipokines levels in the adipose tissue. These results underline the link between iron and lipid dysmetabolism in ceruloplasmin-deficient mice, suggesting that ceruloplasmin in adipose tissue has an anti-inflammatory role rather than a role in iron homeostasis. Furthermore, these data also indicate that ceruloplasmin replacement therapy may be effective at a systemic level.

Neuroimaging Pearls from the MDS Congress Video Challenge. Part 1: Genetic Disorders

We selected several "imaging pearls" presented during the Movement Disorder Society (MDS) Video Challenge for this review. While the event, as implicated by its name, was video-centered, we would like to emphasize the important role of imaging in making the correct diagnosis. We divided this anthology into two parts: genetic and acquired disorders. Genetic cases described herein were organized by the inheritance pattern and the focus was put on the imaging findings and differential diagnoses. Despite the overlapping phenotypes, certain described disorders have pathognomonic MRI brain findings that would provide either the "spot" diagnosis or result in further investigations leading to the diagnosis. Despite this, the diagnosis is often challenging with a broad differential diagnosis, and hallmark findings may be present for only a limited time.

Production of Recombinant Human Ceruloplasmin: Improvements and Perspectives

The ferroxidase ceruloplasmin (CP) plays a crucial role in iron homeostasis in vertebrates together with the iron exporter ferroportin. Mutations in the CP gene give rise to aceruloplasminemia, a rare neurodegenerative disease for which no cure is available. Many aspects of the (patho)physiology of CP are still unclear and would benefit from the availability of recombinant protein for structural and functional studies. Furthermore, recombinant CP could be evaluated for enzyme replacement therapy for the treatment of aceruloplasminemia. We report the production and preliminary characterization of high-quality recombinant human CP in glycoengineered Pichia pastoris SuperMan5. A modified yeast strain lacking the endogenous ferroxidase has been generated and employed as host for heterologous expression of the secreted isoform of human CP. Highly pure biologically active protein has been obtained by an improved two-step purification procedure. Glycan analysis indicates that predominant glycoforms HexNAc2Hex8 and HexNAc2Hex11 are found at Asn119, Asn378, and Asn743, three of the canonical four N-glycosylation sites of human CP. The availability of high-quality recombinant human CP represents a significant advancement in the field of CP biology. However, productivity needs to be increased and further careful glycoengineering of the SM5 strain is mandatory in order to evaluate the possible therapeutic use of the recombinant protein for enzyme replacement therapy of aceruloplasminemia patients.

[Aceruloplasminemia, a rare condition not to be overlooked]

Aceruloplasminemia is a rare iron-overload disease that should be better known by physicians. It is an autosomal recessive disorder due to mutations in ceruloplasmin gene causing systemic iron overload, including cerebral and liver parenchyma. The impairment of ferroxidase ceruloplasmin activity leads to intracellular iron retention leading aceruloplasminemia symptoms. Neurologic manifestations include cognitive impairment, ataxia, extrapyramidal syndrome, abnormal movements, and psychiatric-like syndromes. Physicians should search for aceruloplasminemia in several situations with high ferritin levels: microcytic anaemia, diabetes mellitus, neurological and psychiatric disorders. Diagnosis approach is based on the study of transferrin saturation and hepatic iron content evaluated by magnetic resonance imaging of the liver. Ceruloplasmin dosage is required in case of low transferrin saturation and high hepatic iron content and genetic testing is mandatory in case of serum ceruloplasmin defect. Neurological manifestations occur in the sixties decade and leads to disability. Iron chelators are widely used. Despite their efficacy on systemic and cerebral iron overload, iron chelators tolerance is poor. Early initiation of iron chelation therapy might prevent or slowdown neurodegeneration, highlighting the need for an early diagnosis but their clinical efficacy remains uncertain.

Deferasirox Might Be Effective for Microcytic Anemia and Neurological Symptoms Associated with Aceruloplasminemia: A Case Report and Review of the Literature

The patient was a 64-year-old man presented with difficulty in walking, articulation, and swallowing, as well as cognitive impairment. He had refractory microcytic anemia and diabetes mellitus. His serum levels of iron, copper, and ceruloplasmin were low. Magnetic resonance imaging suggested iron deposition in the basal ganglia, thalami, cerebellar dentate nuclei, and cerebral and cerebellar cortices. He was diagnosed with aceruloplasminemia after a ceruloplasmin gene analysis. Iron chelation therapy with deferasirox improved his anemia and cerebellar symptoms, which included dysarthria and limb ataxia. The present study and previous reports indicate that cerebellar symptoms with aceruloplasminemia might respond to deferasirox in less than one year.

Atypical Anemia as a Clue for an Early Diagnosis

Aceruloplasminemia is a rare autosomal recessive genetic disease characterized by mild microcytic anemia, diabetes, retinopathy, liver disease, and progressive neurological symptoms due to iron accumulation in pancreas, retina, liver, and brain. The disease is caused by mutations in the Ceruloplasmin (CP) gene that produce a strong reduction or absence of ceruloplasmin ferroxidase activity, leading to an impairment of iron metabolism. Most patients described so far are from Japan. Prompt diagnosis and therapy are crucial to prevent neurological complications since, once established, they are usually irreversible. Here, we describe the largest series of non-Japanese patients with aceruloplasminemia published so far, including 13 individuals from 11 families carrying 13 mutations in the CP gene (7 missense, 3 frameshifts, and 3 splicing mutations), 10 of which are novel. All missense mutations were studied by computational modeling. Clinical manifestations were heterogeneous, but anemia, often but not necessarily microcytic, was frequently the earliest one. This study confirms the clinical and genetic heterogeneity of aceruloplasminemia, a disease expected to be increasingly diagnosed in the Next-Generation Sequencing (NGS) era. Unexplained anemia with low transferrin saturation and high ferritin levels without inflammation should prompt the suspicion of aceruloplasminemia, which can be easily confirmed by low serum ceruloplasmin levels. Collaborative joint efforts are needed to better understand the pathophysiology of this potentially disabling disease.

Ceruloplasmin replacement therapy ameliorates neurological symptoms in a preclinical model of aceruloplasminemia

Aceruloplasminemia is a monogenic disease caused by mutations in the ceruloplasmin gene that result in loss of protein ferroxidase activity. Ceruloplasmin plays a role in iron homeostasis, and its activity impairment leads to iron accumulation in liver, pancreas, and brain. Iron deposition promotes diabetes, retinal degeneration, and progressive neurodegeneration. Current therapies mainly based on iron chelation, partially control systemic iron deposition but are ineffective on neurodegeneration. We investigated the potential of ceruloplasmin replacement therapy in reducing the neurological pathology in the ceruloplasmin-knockout (CpKO) mouse model of aceruloplasminemia. CpKO mice were intraperitoneal administered for 2 months with human ceruloplasmin that was able to enter the brain inducing replacement of the protein levels and rescue of ferroxidase activity. Ceruloplasmin-treated mice showed amelioration of motor incoordination that was associated with diminished loss of Purkinje neurons and reduced brain iron deposition, in particular in the choroid plexus. Computational analysis showed that ceruloplasmin-treated CpKO mice share a similar pattern with wild-type animals, highlighting the efficacy of the therapy. These data suggest that enzyme replacement therapy may be a promising strategy for the treatment of aceruloplasminemia.

Aceruloplasminemia: Waiting for an Efficient Therapy

Aceruloplasminemia is an ultra-rare hereditary disorder caused by defective production of ceruloplasmin. Its phenotype is characterized by iron-restricted erythropoiesis and tissue iron overload, diabetes, and progressive retinal and neurological degeneration. Ceruloplasmin is a ferroxidase that plays a critical role in iron homeostasis through the oxidation and mobilization of iron from stores and subsequent incorporation of ferric iron into transferrin (Tf), which becomes available for cellular uptake via the Tf receptor. In addition, ceruloplasmin has antioxidant properties preventing the production of deleterious reactive oxygen species via the Fenton reaction. Some recent findings suggest that aceruloplasminemia phenotypes can be more heterogeneous than previously believed, varying within a wide range. Within this large heterogeneity, microcytosis with or without anemia, low serum iron and high serum ferritin, and diabetes are the early hallmarks of the disease, while neurological manifestations appear 10-20 years later. The usual therapeutic approach is based on iron chelators that are efficacious in reducing systemic iron overload. However, they have demonstrated poor efficacy in counteracting the progression of neurologic manifestations, and also often aggravate anemia, thereby requiring drug discontinuation. Open questions remain regarding the mechanisms leading to neurological manifestation and development of diabetes, and iron chelation therapy (ICT) efficacy. Recent studies in animal models of aceruloplasminemia support the possibility of new therapeutic approaches by parenteral ceruloplasmin administration. In this review we describe the state of the art of aceruloplasminemia with particular attention on the pathogenic mechanisms of the disease and therapeutic approaches, both current and perspective.

Inherited Disorders of Iron Overload

Dietary iron absorption and systemic iron traffic are tightly controlled by hepcidin, a liver-derived peptide hormone. Hepcidin inhibits iron entry into plasma by binding to and inactivating the iron exporter ferroportin in target cells, such as duodenal enterocytes and tissue macrophages. Hepcidin is induced in response to increased body iron stores to inhibit further iron absorption and prevent iron overload. The mechanism involves the BMP/SMAD signaling pathway, which triggers transcriptional hepcidin induction. Inactivating mutations in components of this pathway cause hepcidin deficiency, which allows inappropriately increased iron absorption and efflux into the bloodstream. This leads to hereditary hemochromatosis (HH), a genetically heterogenous autosomal recessive disorder of iron metabolism characterized by gradual buildup of unshielded non-transferrin bound iron (NTBI) in plasma and excessive iron deposition in tissue parenchymal cells. The predominant HH form is linked to mutations in the HFE gene and constitutes the most frequent genetic disorder in Caucasians. Other, more severe and rare variants are caused by inactivating mutations in HJV (hemojuvelin), HAMP (hepcidin) or TFR2 (transferrin receptor 2). Mutations in SLC40A1 (ferroportin) that cause hepcidin resistance recapitulate the biochemical phenotype of HH. However, ferroportin-related hemochromatosis is transmitted in an autosomal dominant manner. Loss-of-function ferroportin mutations lead to ferroportin disease, characterized by iron overload in macrophages and low transferrin saturation. Aceruloplasminemia and atransferrinemia are further inherited disorders of iron overload caused by deficiency in ceruloplasmin or transferrin, the plasma ferroxidase and iron carrier, respectively.

Aceruloplasminemia with Abnormal Compound Heterozygous Mutations Developed Neurological Dysfunction during Phlebotomy Therapy

Aceruloplasminemia is an autosomal recessive inherited disorder caused by ceruloplasmin gene mutations. The loss of ferroxidase activity of ceruloplasmin due to gene mutations causes a disturbance in cellular iron transport. We herein describe a patient with aceruloplasminemia, who presented with diabetes mellitus that was treated by insulin injections, liver hemosiderosis treated by phlebotomy therapy, and neurological impairment. A genetic analysis of the ceruloplasmin gene revealed novel compound heterozygous mutations of c.1286_1290insTATAC in exon 7 and c.2185delC in exon 12. This abnormal compound heterozygote had typical clinical features similar to those observed in aceruloplasminemia patients with other gene mutations.

Pancytopenia and Myelodysplastic Changes in Aceruloplasminemia: A Case with a Novel Pathogenic Variant in the Ceruloplasmin Gene

A 72-year-old Japanese woman suffered from mild pancytopenia 3 years before her initial hospitalization. On admission, the levels of trace elements, particularly copper, and ceruloplasmin were significantly decreased in her blood serum. Abdominal lymphadenopathy and bone marrow dysplasia were detected. Hemosiderin deposition was observed in her lymph nodes and bone marrow, and magnetic resonance imaging suggested its deposition in various organs. A novel missense pathogenic variant (c.T1670G) was detected in the ceruloplasmin gene, resulting in an amino acid change (p.M557R). When copper deficiency is accompanied by cytopenia and dysplasia in a patient, it is worthwhile to consider a differential diagnosis of aceruloplasminemia.

The Resection of Thyroid Cancer Was Associated with the Resolution of Hyporesponsiveness to an Erythropoiesis-stimulating Agent in a Hemodialysis Patient with Aceruloplasminemia

We herein report the case of a hemodialysis patient whose response to an erythropoiesis-stimulating agent (ESA) improved following the resection of thyroid cancer. Her hemoglobin level remained below 7 g/dL, despite the use of ESA. During the search for the causes of her hyporesponsiveness to ESA, papillary thyroid cancer and aceruloplasminemia were found. The existence of other potential causes, such as iron deficiency, infectious disease, severe hyperparathyroidism and malnutrition were ruled out. Following the resection of the thyroid cancer tumor, her hemoglobin level increased to 10.2 g/dL over a period of 4 months. This is the first report to demonstrate the resolution of hyporesponsiveness to ESA following the resection of a malignant tumor.

Case of presymptomatic aceruloplasminemia treated with deferasirox

Aceruloplasminemia is an autosomal recessive disease characterized by an abnormal iron metabolism. The absence of ferroxidase activity caused by mutation of ceruloplasmin leads to iron overload in the brain, liver and other organs. We report a 35-year-old man who was diagnosed with aceruloplasminemia without neurological manifestation despite the accumulation of iron in the brain and liver. To prevent the development of neurodegenerative disorder related to iron toxicity, iron depletion therapy was performed. Iron chelator deferasirox was effective in reducing serum ferritin level and to prevent the progression of the disease.

Schizophrenia-like psychosis and aceruloplasminemia

Schizophrenia-like illnesses occur in a variety of medical and neurological conditions but to date have not been described in association with aceruloplasminemia. Aceruloplasminemia is an autosomal recessive disorder of iron metabolism which leads to iron deposition in the basal ganglia, thalamus, cerebellum and hippocampus and which usually presents in middle age with extrapyramidal symptoms and dementia. We describe a 21-year-old woman on treatment for aceruloplasminemia who presented with schizophrenia-like psychosis and declining function in the absence of neurological signs. Neuropsychological testing showed significant dominant hemisphere deficits. Magnetic resonance imaging showed bilateral iron deposition in the cerebellar dentate nuclei and thalami, frontal atrophy, and periventricular white matter hyperintensities. Functional imaging suggested global hypoperfusion. The clinical, cognitive and imaging findings were not typical for either aceruloplasminemia or schizophrenia alone and the possible relationship between the two disorders is discussed with particular reference to implications for our understanding of schizophrenia.