Gene therapy for lysosomal storage diseases and peroxisomal diseases.

Gene therapies for lysosomal storage diseases (LSD) and peroxisomal diseases (PD) are rapidly advancing. Most LSDs and PDs are characterized by brain involvement, prompting the development of therapies targeting the brain. There are two types of gene therapy for brain involvement in LSD and PD, i.e., the direct transfer of a therapeutic gene into brain cells and hematopoietic stem cell-targeted gene therapy. The rationale for the latter approach is that brain microglia are derived from hematopoietic cells. Thus, gene-corrected hematopoietic cells migrate into the brain and differentiate into microglial cells. These gene-corrected microglial cells correct the metabolic defects associated with LSD and reduce inflammation in PD and LSD, leading to a clinical benefit. Gene editing technology has recently been applied in this area and a trial focused on LSD is currently ongoing. Although these approaches are still under investigation, very encouraging results have been obtained. This review provides an overview of recently developed gene therapies for various LSDs and PDs, including the results of clinical trials, with an emphasis on the benefits of this approach for these diseases.

The many faces of peroxisomal disorders: Lessons from a large Arab cohort.

Defects in the peroxisomes biogenesis and/or function result in peroxisomal disorders. In this study, we describe the largest Arab cohort to date (72 families) of clinically, biochemically and molecularly characterized patients with peroxisomal disorders. At the molecular level, we identified 43 disease-causing variants, half of which are novel. The founder nature of many of the variants allowed us to calculate the minimum disease burden for these disorders in our population ~1:30 000, which is much higher than previous estimates in other populations. Clinically, we found an interesting trend toward genotype/phenotype correlation in terms of long-term survival. Nearly half (40/75) of our peroxisomal disorders patients had documented survival beyond 1 year of age. Most unusual among the long-term survivors was a multiplex family in which the affected members presented as adults with non-specific intellectual disability and epilepsy. Other unusual presentations included the very recently described peroxisomal fatty acyl-CoA reductase 1 disorder as well as CRD, spastic paraparesis, white matter (CRSPW) syndrome. We conclude that peroxisomal disorders are highly heterogeneous in their clinical presentation. Our data also confirm the demonstration that milder forms of Zellweger spectrum disorders cannot be ruled out by the "gold standard" very long chain fatty acids assay, which highlights the value of a genomics-first approach in these cases.

Peroxisomal disorders: Improved laboratory diagnosis, new defects and the complicated route to treatment.

Peroxisomes catalyze a number of essential metabolic functions of which fatty acid alpha- and beta-oxidation, ether phospholipid biosynthesis, glyoxylate detoxification and bile acid synthesis are the most important. The key role of peroxisomes in humans is exemplified by the existence of a group of peroxisomal disorders, caused by mutations in > 30 different genes which code for proteins with a role in either peroxisome biogenesis or one of the metabolic pathways in peroxisomes. Technological advances in laboratory methods at the metabolite-, enzyme-, and molecular level have not only allowed the identification of new peroxisomal disorders but also new phenotypes associated with already identified genetic defects thus extending the clinical spectrum. Unfortunately, progress in the field of pathogenesis and treatment has lagged behind although there are certainly new and hopeful developments with respect to X-linked adrenoleukodystrophy and hyperoxaluria type 1.

Peroxisome biogenesis disorders in the Zellweger spectrum: An overview of current diagnosis, clinical manifestations, and treatment guidelines.

Peroxisome biogenesis disorders in the Zellweger spectrum (PBD-ZSD) are a heterogeneous group of genetic disorders caused by mutations in PEX genes responsible for normal peroxisome assembly and functions. As a result of impaired peroxisomal activities, individuals with PBD-ZSD can manifest a complex spectrum of clinical phenotypes that typically result in shortened life spans. The extreme variability in disease manifestation ranging from onset of profound neurologic symptoms in newborns to progressive degenerative disease in adults presents practical challenges in disease diagnosis and medical management. Recent advances in biochemical methods for newborn screening and genetic testing have provided unprecedented opportunities for identifying patients at the earliest possible time and defining the molecular bases for their diseases. Here, we provide an overview of current clinical approaches for the diagnosis of PBD-ZSD and provide broad guidelines for the treatment of disease in its wide variety of forms. Although we anticipate future progress in the development of more effective targeted interventions, the current guidelines are meant to provide a starting point for the management of these complex conditions in the context of personalized health care.

Propofol infusion syndrome or adrenoleukodystrophy?

Following a propofol anesthetic, a 5-year-old girl with lower extremity spasticity seized and developed hypertriglyceridemia, hyperkalemia, and metabolic acidosis. A presumed diagnosis of propofol infusion syndrome (PRIS) was made, but further investigation revealed neonatal adrenoleukodystrophy. PRIS should be considered with this constellation of symptoms, but other neurometabolic disorders must always be ruled out.

Stop Codon Context-Specific Induction of Translational Readthrough.

Premature termination codon (PTC) mutations account for approximately 10% of pathogenic variants in monogenic diseases. Stimulation of translational readthrough, also known as stop codon suppression, using translational readthrough-inducing drugs (TRIDs) may serve as a possible therapeutic strategy for the treatment of genetic PTC diseases. One important parameter governing readthrough is the stop codon context (SCC)-the stop codon itself and the nucleotides in the vicinity of the stop codon on the mRNA. However, the quantitative influence of the SCC on treatment outcome and on appropriate drug concentrations are largely unknown. Here, we analyze the readthrough-stimulatory effect of various readthrough-inducing drugs on the SCCs of five common premature termination codon mutations of PEX5 in a sensitive dual reporter system. Mutations in PEX5, encoding the peroxisomal targeting signal 1 receptor, can cause peroxisomal biogenesis disorders of the Zellweger spectrum. We show that the stop context has a strong influence on the levels of readthrough stimulation and impacts the choice of the most effective drug and its concentration. These results highlight potential advantages and the personalized medicine nature of an SCC-based strategy in the therapy of rare diseases.

The Δ4-desaturation pathway for DHA biosynthesis is operative in the human species: differences between normal controls and children with the Zellweger syndrome.

BACKGROUND: Docosahexaenoic acid (DHA, 22:6ω3) is a fundamental component of cell membranes, especially in the brain and retina. In the experimental animal, DHA deficiency leads to suboptimal neurological performance and visual deficiencies. Children with the Zellweger syndrome (ZS) have a profound DHA deficiency and symptoms that can be attributed to their extremely low DHA levels. These children seem to have a metabolic defect in DHA biosynthesis, which has never been totally elucidated. Treatment with DHA ethyl ester greatly improves these patients, but if we could normalize their endogenous DHA production we could get additional benefits. We examined whether DHA biosynthesis by Δ4-desaturation could be enhanced in the human species by transfecting the enzyme, and if this could normalize the DHA levels in cells from ZS patients. RESULTS: We showed that the Δ4-desaturase gene (Fad4) from Thraustochytrium sp, which can be expressed by heterologous transfection in other plant and yeast cells, can also be transfected into human lymphocytes, and that it expresses the enzyme (FAD4, Δ4-desaturase) by producing DHA from direct Δ4-desaturation of 22:5ω3. We also found that the other substrate for Δ4-desaturase, 22:4ω6, was parallely desaturated to 22:5ω6. CONCLUSIONS: The present "in vitro" study demonstrates that Δ4-desaturase can be transfected into human cells and synthesize DHA (as well as 22:5ω6, DPA) from 22:5ω3 and 22:4ω6, respectively, by putative Δ4-desaturation. Even if this pathway may not be the physiological route for DHA biosynthesis "in vivo", the present study opens new perspectives for the treatment of patients within the ZS spectrum.

[Mechanism of action of cell therapy in hereditary diseases]. / Mecanismo de acción de la terapia celular en enfermedades hereditarias.

Inherited metabolism disorders are serious childhood diseases that lead to significant cognitive impairment and regression of psychomotor development. The pathophysiology of the neural progressive deterioration is usually associated with severe neuroinflammation and demyelination, and as a consequence, neurodegeneration. At the moment they have no adequate treatment and require early and aggressive therapeutic approaches, which entail high mortality rates and, very frequently, low degrees of functional improvement and survival. Bone marrow transplantation and bone marrow mesenchymal cells grafts are therapeutic and experimental therapies that improve the course of these diseases through different mechanisms of action: enzyme replacement, membrane exchange and regulation of the inflammatory process.

Los trastornos heredados del metabolismo son enfermedades graves de la infancia que cursan con un gran deterioro cognitivo y del desarrollo psicomotor. La fisiopatología del progresivo deterioro del sistema nervioso suele estar asociada a una severa neuroinflamación y desmielinización, y como consecuencia, neurodegeneración. Por el momento no tienen cura y precisan de actitudes terapéuticas precoces y agresivas, que conllevan altas tasas de mortalidad y, muy frecuentemente, escasos grados de mejoría funcional y supervivencia. El trasplante de médula ósea y de células mesenquimales de médula ósea son terapias de elección y experimentales que consiguen mejorar el curso de estas enfermedades mediante diferentes mecanismos de acción: remplazo de enzima deficiente, intercambio de membranas y regulación del proceso inflamatorio.

Adrenoleukodystrophy in the era of newborn screening.

PURPOSE OF REVIEW: Adrenoleukodystrophy (ALD) is a peroxisomal disorder with varying clinical presentations, including adrenal insufficiency, neurologic disease, and testicular dysfunction. The present review is intended to describe the current knowledge of the pathophysiology of ALD and provide an update regarding newborn screening, diagnosis, monitoring, and treatment. RECENT FINDINGS: New York State initiated newborn screening for ALD on December 30, 2013. Successful ALD newborn screening has led to its addition on other state newborn screens and recommendations for universal screening. Initial incidence reports, based on newborn screening, suggest ALD may be more common than previously described. The Pediatric Endocrine Society has published guidance for monitoring newborn males with ALD and case reports suggest biochemical adrenal insufficiency can be present during early infancy. Allogeneic hematopoietic stem cell transplant and gene therapy have been effective at halting the progression of cerebral ALD. SUMMARY: Early diagnosis and monitoring for progression of ALD can prevent adrenal crisis and treat the cerebral form of the disease. Initial guidelines for surveillance are likely to evolve as newborn screening not only aids in early detection and therapeutic interventions for ALD, but also expands our knowledge of the natural history of ALD.

Umbilical cord-blood transplantations from unrelated donors in patients with inherited metabolic diseases: Single-institute experience.

We evaluated the feasibility of UCBT from unrelated donors and a myeloablative preparative regimen that did not involve anti-thymocyte globulin in five children with lysosomal and peroxisomal diseases. Patients with MPS II (n = 1), adrenoleukodystrophy (n = 1), metachromatic leukodystrophy (n = 2), and Krabbe disease (n = 1) received UCBT between December 2001 and September 2005. All patients received oral Bu (600 mg/m2), CY (200 mg/kg IV), and fludarabine (180 mg/m2 IV). Prophylaxis for GVHD consisted of a combination of tacrolimus and a short methotrexate course. Neutrophil engraftment occurred a median of 24 days (range, 21-25) after transplantation. None had graft rejection. One patient developed grade III acute GVHD and the other four patients had grade I acute GVHD; none had extensive chronic GVHD. One patient developed hemorrhagic cystitis. There were no treatment-related deaths. Although one child with MPS II died of PTLD 10 months after the UCBT, four of the five children are alive 14, 20, 31, and 55 months after transplantation with complete donor chimerism. These results suggest the feasibility of the UCBT with Bu, fludarabine, and CY-preparative regimen for patients with inherited metabolic diseases.

Inborn Errors of Metabolism Involving Complex Molecules: Lysosomal and Peroxisomal Storage Diseases.

Peroxisomes and lysosomes are distinct subcellular compartments that underlie several pediatric metabolic disorders. Knowledge of their function and cell biology leads to understanding how the disorders result from genetic defects. Diagnostic and therapeutic approaches for the disorders take advantage of the cell biology mechanisms. Whereas peroxisomal disorders are characterized by enzymatic defects in peroxisomal pathways leading to metabolic and lipid changes, lysosomal storage disorders are marked by accumulation of substrates of lysosomal pathways inside the lysosome. The human diseases related to these two organelles are reviewed, focusing on general disease patterns and underlying diagnosis and treatment principles.

[Hereditary peroxisomal diseases]. / Maladies peroxysomales.

Peroxisomes are small intracellular organelles that catalyse key metabolic reactions such as the beta-oxidation of some straight-chain or branched-chain fatty acids and the alpha-oxidation of phytanic acid. These enzyme reactions produce hydrogen peroxide, which is subsequently neutralized by the peroxisomal catalase. Peroxisomes also metabolize glyoxylate to glycine, and catalyze the first steps of plasmalogen biosynthesis. There are more than a dozen inherited peroxisomal disorders in humans. These metabolic diseases are due to monogenic defects that affect either a single function (such as enzyme or a transporter) or more than two distinct functions because of the impairment of several aspects of peroxisome biogenesis. With the notable exception of X-linked adrenoleucodystrophy, these inborn disorders are transmitted as autosomal recessive traits. Their clinical presentation can be very heterogeneous, and include neonatal, infantile or adult forms. The present review describes the symptomatology of these genetic diseases, the underlying genetic and biochemical alterations, and summarizes their diagnostic approach.

Bone marrow-derived mesenchymal stem cells remain host-derived despite successful hematopoietic engraftment after allogeneic transplantation in patients with lysosomal and peroxisomal storage diseases.

Human bone marrow contains mesenchymal stem cells (MSCs) that can differentiate into various cells of mesenchymal origin. We developed an efficient method of isolating and culture expanding a homogenous population of MSCs from bone marrow and determined that MSCs express alpha-L-iduronidase, arylsulfatase-A and B, glucocerebrosidase, and adrenoleukodystrophy protein. These findings raised the possibility that MSCs may be useful in the treatment of storage disorders. To determine if donor derived MSCs are transferred to the recipients with lysosomal or peroxisomal storage diseases by allogeneic hematopoietic stem cell (HSC) transplantation, we investigated bone marrow derived MSCs of 13 patients 1-14 years after allogeneic transplantation. Highly purified MSCs were genotyped either by fluorescence in situ hybridization using probes for X and Y-chromosomes in gender mis-matched recipients or by radiolabeled PCR amplification of polymorphic simple sequence repeats. Phenotype was determined by the measurement of disease specific protein/enzyme activity in purified MSCs. We found that MSCs isolated from recipients of allogeneic HSC transplantation are not of donor genotype and have persistent phenotypic defects despite successful donor type hematopoietic engraftment. Whether culture expanded normal MSCs can be successfully transplanted into patients with storage diseases and provide therapeutic benefit needs to be determined.

Mecanismo de acción de la terapia celular en enfermedades hereditarias / Mechanism of action of cell therapy in hereditary diseases

Los trastornos heredados del metabolismo son enfermedades graves de la infancia que cursan con un gran deterioro cognitivo y del desarrollo psicomotor. La fisiopatología del progresivo deterioro del sistema nervioso suele estar asociada a una severa neuroinflamación y desmielinización, y como consecuencia, neurodegeneración. Por el momento no tienen cura y precisan de actitudes terapéuticas precoces y agresivas, que conllevan altas tasas de mortalidad y, muy frecuentemente, escasos grados de mejoría funcional y supervivencia. El trasplante de médula ósea y de células mesenquimales de médula ósea son terapias de elección y experimentales que consiguen mejorar el curso de estas enfermedades mediante diferentes mecanismos de acción: remplazo de enzima deficiente, intercambio de membranas y regulación del proceso inflamatorio.

Inherited metabolism disorders are serious childhood diseases that lead to significant cognitive impairment and regression of psychomotor development. The pathophysiology of the neural progressive deterioration is usually associated with severe neuroinflammation and demyelination, and as a consequence, neurodegeneration. At the moment they have no adequate treatment and require early and aggressive therapeutic approaches, which entail high mortality rates and, very frequently, low degrees of functional improvement and survival. Bone marrow transplantation and bone marrow mesenchymal cells grafts are therapeutic and experimental therapies that improve the course of these diseases through different mechanisms of action: enzyme replacement, membrane exchange and regulation of the inflammatory process.

Adrenoleukodystrophy: molecular genetics, pathology, and Lorenzo's oil.

Knowledge about adrenoleukodystrophy (ALD), a disorder which was described first in 1923, has increased greatly during recent years. The principal biochemical abnormality, the presumed enzyme defect, and the gene defect, have been defined. A dietary therapy has been proposed and attracted world-wide attention through a motion picture. Nevertheless, many questions remain and cannot be answered without a more fundamental understanding of pathology and pathogenesis. This article will provide a review of the history, clinical features, pathology, biochemistry, and the gene defect, and then appraise current efforts to clarify pathogenesis and develop therapeutic approaches.

Hepatocyte transplantation in a 4-year-old girl with peroxisomal biogenesis disease: technique, safety, and metabolic follow-up.

Hepatocyte transplantation is an investigational alternative to orthotopic liver transplantation to treat liver based inborn errors of metabolism. We report successful hepatocyte transplantation in a 4-year-old girl with infantile Refsum disease. Hepatocytes were isolated from the left liver segment of two male donors using a classic two-step perfusion method. Fresh cells were transplanted first and then cryopreserved cells, for a total of 2 billion cells. Total bile acids and abnormal dihydroxycoprostanoïc acid markedly decreased in the patient's serum, indicating resolution of cholestasis and re-population of liver cells. Pipecholic acid decreased by 40% and c26:c22 fatty acid ratio by 36% after 18 months. Donor chromosomes sequences were detected on biopsy posttransplant, indicating engraftment. Hepatocyte transplantation is a safe and promising technique in the treatment of rare inborn errors of metabolism. Future improvements of cell viability and prevention of apoptosis may increase engraftment and subsequent re-population.

Therapeutic developments in peroxisome biogenesis disorders.

Clinically, peroxisome biogenesis disorders (PBDs) are a group of lethal diseases with a continuum of severity of clinical symptoms ranging from the most severe form, Zellweger syndrome, to the milder forms, infantile Refsum disease and rhizomelic chondrodysplasia punctata. PBDs are characterised by a number of biochemical abnormalities including impaired degradation of peroxide, very long chain fatty acids, pipecolic acid, phytanic acid and xenobiotics and impaired synthesis of plasmalogens, bile acids, cholesterol and docosahexaenoic acid. Treatment of PBD patients as a group is problematic since a number of patients, especially those with Zellweger syndrome, have significant neocortical alterations in the brain at birth so that full recovery would be impossible even with postnatal therapy. To date, treatment of PBD patients has generally involved only supportive care and symptomatic therapy. However, the fact that some of the milder PBD patients live into the second decade has prompted research into possible treatments for these patients. A number of experimental therapies have been evaluated to determine whether or not correction of biochemical abnormalities through dietary supplementation and/or modification is of clinical benefit to PBD patients. Another approach has been pharmacological induction of peroxisomes in PBD patients to improve overall peroxisomal biochemical function. Well known rodent peroxisomal proliferators were found not to induce human peroxisomes. Recently, our laboratory demonstrated that sodium 4-phenylbutyrate induces peroxisome proliferation and improves biochemical function (very long chain fatty acid beta-oxidation rates and very long chain fatty acid and plasmalogens levels) in fibroblast cell lines from patients with milder PBD phenotypes. Dietary supplementation and/or modification and pharmacological induction of peroxisomes as treatment strategies for PBD patients will be the subject of this review.

Microglia: the effector cell for reconstitution of the central nervous system following bone marrow transplantation for lysosomal and peroxisomal storage diseases.

Treatment and potential cure of lysosomal and peroxisomal diseases, heretofore considered fatal, has become a reality during the past decade. Bone marrow transplantation, (BMT), has provided a method for replacement of the disease-causing enzyme deficiency. Cells derived from the donor marrow continue to provide enzyme indefinitely. Several scores of patients with diseases as diverse as metachromatic leukodystrophy, adrenoleukodystrophy, globoid cell leukodystrophy, Hurler syndrome (MPS I-H), Maroteaux-Lamy (MPS VI) Gaucher disease, and fucosidosis have been successfully treated following long-term engraftment. Central nervous system (CNS) manifestations are also prevented or ameliorated in animal models of these diseases following engraftment from normal donors. The microglial cell system has been considered to be the most likely vehicle for enzyme activity following bone marrow engraftment. Microglia in the mature animal or human are derived from the newly engrafted bone marrow. Graft-v-host disease activation of the microglia is also of importance. This article will summarize some of the pertinent literature relative to the role of microglia in such transplant processes.

Proton MR spectroscopy of childhood adrenoleukodystrophy.

PURPOSE: To determine the potential of proton MR spectroscopy to monitor patients with childhood-onset cerebral adrenoleukodystrophy (COCALD). METHODS: Single-voxel MR spectroscopy was performed in 16 children with COCALD (24 examinations) who had had no treatment and in 7 children (13 examinations) who had had bone marrow transplantation. RESULTS: In the untreated children with clinically active COCALD, the metabolite ratios N-acetyl-aspartate (NAA)/creatine (Cr) and NAA/choline (Ch) were decreased while Ch/Cr was increased. This trend agrees well with those reported by other researchers, although different experimental sequences and parameters were used in our study. Comparison of these ratios with those from a control group yielded significant differences in the occipital region. In the children who were clinically stable after bone marrow transplantation, the mean levels of the three ratios were between those of the control subjects and the patients with untreated COCALD: the differences in these ratios approached significance. In patients who had been monitored periodically, MR spectroscopy metabolite ratios correlated well with the dementia rating score, reflecting clinical status. CONCLUSION: There is good correlation between MR spectroscopy metabolite ratios and a patient's clinical status. MR spectroscopy appears to be a useful, noninvasive tool to monitor patients with adrenoleukodystrophy, and it increases the overall sensitivity of MR techniques in clinical applications.