Biomedical subjects

Mimoun Azzouz

Publications and source records attributed to Mimoun Azzouz.

15 recordsLinked to original sources

PubMed2026

Hypothesis-free evaluation of circulating metabolome provides cell-specific insights regarding the role of energy substrate availability in amyotrophic lateral sclerosis.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with limited therapeutic options. The circulating metabolome comprises small molecules present in plasma/serum which are the intermediates and end-products of cellular metabolism, and is linked to ALS pathogenesis. METHODS: We conducted hypothesis-free two-sample Mendelian randomisation (MR) analysis of the concentration of 575 plasma/serum metabolites, to determine which are causally linked to risk of ALS. Significant metabolites were validated in an independent GWAS of plasma/serum metabolite concentrations and evaluated for sex-specific effects. Correlations between directly measured patient biofluid metabolite concentrations and ALS risk/severity were examined in 94 ALS patients and 40 controls. We experimentally assessed metabolic function in a murine neurons and human astrocytes carrying an ALS-associated G4C2-repeat expansion within C9orf72. RESULTS: MR causally associated five metabolites with ALS risk after multiple-testing correction. Higher serum concentration of glycoprotein acetyls (P = 9.7e - 9, β = 0.21) and the peptide DSGEGDFXAEGGGVR (P = 8.0e - 6, β = 0.22) was associated with increased ALS risk, whereas higher plasma concentration of phenylalanylserine, isobutyrylcarnitine, and acetylcarnitine was protective (P < 5e - 5, β = - 0.29 to - 0.72). DSGEGDFXAEGGGVR has been linked to glucose metabolism but we have used genetic fine-mapping to link DSGEGDFXAEGGGVR, neuronal glucose uptake through GLUT3, and ALS risk. Direct measurement of metabolite concentrations in patient biofluids revealed elevated acetylcarnitine levels in patients with ALS, which were associated with delayed symptom onset (Cox regression, P = 0.02, HR = 0.4). Similarly, lactate is elevated in ALS patient CSF (ANOVA, P = 1.3e - 3) and in patients with longer survival time (Cox regression, P = 0.03, HR = 0.3). Plasma fructose is elevated in ALS patients with shorter survival time (Cox regression, P = 0.02, HR = 1.1). In vitro, neurons and astrocytes carrying an ALS-associated G4C2-repeat expansion within C9orf72 demonstrated reduced metabolic flexibility. CONCLUSIONS: We provide evidence that impaired energy substrate availability contributes to ALS risk and severity. CNS cell types differ in their use of energy substrates and therefore we postulate the relative importance of different cell types for different stages of disease. Our findings support further investigation of metabolic interventions to treat or prevent ALS.

Amyotrophic Lateral Sclerosis↗

PubMed2006

Gene Therapy for ALS: progress and prospects.

Amyotrophic lateral sclerosis (ALS) is a devastating disease for which there are no effective drug treatments to date. Recent advances in Gene Therapy open up the possibility of developing an effective treatment aiming at halting or delaying the degeneration of motor neurons. Viral vectors such as lentiviral vectors and adeno-associated virus can transfer genes into many different types of primary neurons from a broad range of species including man and the resulting gene expression is long-term. Numerous animal studies have now been undertaken with these vectors and correction of disease models has been obtained. These vectors have been refined to a very high level and can be produced safely for the clinic. However, we believe that there are some major issues that need to be addressed in order to see a Gene Therapy approach with viral vectors proceed to the clinic for ALS patients. This review will describe the general features of lentiviral vectors. It will then describe some key examples of gene transfer and genetic correction in animal models of motor neuron disease. The prospects for the clinical evaluation of lentiviral vectors for the treatment of human motor neuron disease will be outlined.

Amyotrophic Lateral Sclerosis↗

PubMed2006

Gene therapy for neurodegenerative and ocular diseases using lentiviral vectors.

Gene therapy holds great promise for the treatment of a wide range of inherited and acquired disorders. The development of viral vector systems to mediate safe and long-lasting expression of therapeutic transgenes in specific target cell populations is continually advancing. Gene therapy for the nervous system is particularly challenging due to the post-mitotic nature of neuronal cells and the restricted accessibility of the brain itself. Viral vectors based on lentiviruses provide particularly attractive vehicles for delivery of therapeutic genes to treat neurological and ocular diseases, since they efficiently transduce non-dividing cells and mediate sustained transgene expression. Furthermore, novel routes of vector delivery to the nervous system have recently been elucidated and these have increased further the scope of lentiviruses for gene therapy application. Several studies have demonstrated convincing therapeutic efficacy of lentiviral-based gene therapies in animal models of severe neurological disorders and the push for progressing such vectors to the clinic is ongoing. This review describes the key features of lentiviral vectors that make them such useful tools for gene therapy to the nervous system and outlines the major breakthroughs in the potential use of such vectors for treating neurodegenerative and ocular diseases.

Animals↗

PubMed2005

Retinoic acid receptor beta2 promotes functional regeneration of sensory axons in the spinal cord.

The embryonic CNS readily undergoes regeneration, unlike the adult CNS, which has limited axonal repair after injury. Here we tested the hypothesis that retinoic acid receptor beta2 (RARbeta2), critical in development for neuronal growth, may enable adult neurons to grow in an inhibitory environment. Overexpression of RARbeta2 in adult rat dorsal root ganglion cultures increased intracellular levels of cyclic AMP and stimulated neurite outgrowth. Stable RARbeta2 expression in DRG neurons in vitro and in vivo enabled their axons to regenerate across the inhibitory dorsal root entry zone and project into the gray matter of the spinal cord. The regenerated neurons enhanced second-order neuronal activity in the spinal cord, and RARbeta2-treated rats showed highly significant improvement in sensorimotor tasks. These findings show that RARbeta2 induces axonal regeneration programs within injured neurons and may thus offer new therapeutic opportunities for CNS regeneration.

Animals↗

PubMed2005

Trophic activity of Rabies G protein-pseudotyped equine infectious anemia viral vector mediated IGF-I motor neuron gene transfer in vitro.

The present study examines gene delivery to cultured motor neurons (MNs) with the Rabies G protein (RabG)-pseudotyped lentiviral equine infectious anemia virus (RabG.EIAV) vector. RabG.EIAV-mediated beta-galactosidase (RabG.EIAV-LacZ) gene expression in cultured MNs plateaus 120 h after infection. The rate and percent of gene expression observed are titer-dependent (P < 0.001). The rat IGF-I cDNA sequence was then cloned into a RabG.EIAV vector (RabG.EIAV-IGF-I) and was shown to induce IGF-I expression in HEK 293 cells. MNs infected with RabG.EIAV-IGF-I demonstrate enhanced survival compared to MNs infected with RabG.EIAV-LacZ virus (P < 0.01). In addition, IGF-I expression in cultured MNs induced profound MN axonal elongation compared to control virus (P < 0.01). The enhanced motor neuron tropism of RabG.EIAV previously demonstrated in vivo, together with the trophic effects of RabG.EIAV-IGF-I MN gene expression may lend this vector to therapeutic application in motor neuron disease.

Animals↗

PubMed2005

Silencing mutant SOD1 using RNAi protects against neurodegeneration and extends survival in an ALS model.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease resulting in the selective death of motor neurons in the brain and spinal cord. Some familial cases of ALS are caused by dominant mutations in the gene encoding superoxide dismutase (SOD1). The emergence of interfering RNA (RNAi) for specific gene silencing could be therapeutically beneficial for the treatment of such dominantly inherited diseases. We generated a lentiviral vector to mediate expression of RNAi molecules specifically targeting the human SOD1 gene (SOD1). Injection of this vector into various muscle groups of mice engineered to overexpress a mutated form of human SOD1 (SOD1(G93A)) resulted in an efficient and specific reduction of SOD1 expression and improved survival of vulnerable motor neurons in the brainstem and spinal cord. Furthermore, SOD1 silencing mediated an improved motor performance in these animals, resulting in a considerable delay in the onset of ALS symptoms by more than 100% and an extension in survival by nearly 80% of their normal life span. These data are the first to show a substantial extension of survival in an animal model of a fatal, dominantly inherited neurodegenerative condition using RNAi and provide the highest therapeutic efficacy observed in this field to date.

Amyotrophic Lateral Sclerosis↗

PubMed2005

Therapeutic gene silencing in neurological disorders, using interfering RNA.

The development of interfering RNA (RNAi) from a naturally occurring phenomenon to a tool for mediating highly specific gene silencing provides an exciting prospect as a novel therapeutic strategy for a wide range of disorders. Although the efficacy of RNAi as a research tool for analysing gene function has been well demonstrated in several cell types, the therapeutic potential of RNAi-mediated gene silencing has only recently started to be investigated. Several neurodegenerative disorders provide particularly suitable candidates for RNAi based therapy; however, many hurdles preclude the success of therapeutic application. These include the challenge of delivering active RNAi molecules to the specific target cell populations where they are required and appropriate regulation of gene suppression, such as to maintain a long-lasting therapeutic effect. Furthermore, for safety reasons, off-target effects should be minimised. Here we review the advancement of RNAi technology for therapeutic application and highlight the potential of targeted gene silencing for the treatment of neurodegenerative diseases.

Amyotrophic Lateral Sclerosis↗

PubMed2005

Lentivector-mediated delivery of GDNF protects complex motor functions relevant to human Parkinsonism in a rat lesion model.

Although viral vector-mediated delivery of glial cell-line derived neurotrophic factor (GDNF) to the brain has considerable potential as a neuroprotective strategy in Parkinson's disease (PD), its ability to protect complex motor functions relevant to the human condition has yet to be established. In this study, we used an operant task that assesses the selection, initiation and execution of lateralized nose-pokes in Lister Hooded rats to assess the efficacy with which complex behaviours are protected against neurotoxic lesions by prior injection of a lentiviral vector expressing GDNF. Unilateral injection of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle (MFB) caused rats to attempt fewer trials and to make more procedural errors. Lesioned rats also developed a pronounced ipsilateral bias, with a corresponding drop in contralateral accuracy. They were also slower to react to contralateral stimuli and to execute movements bilaterally. Rats that were pre-treated 4 weeks prior to lesion surgery with an equine infectious anaemia virus (EIAV) vector carrying GDNF [EIAV-GDNF, injected into the striatum and above the substantia nigra (SN)] performed significantly better on all of these parameters than control rats. In addition to the operant task, EIAV-GDNF successfully rescued contralateral impairments in the corridor, staircase, stepping and cylinder tasks, and prevented drug-induced rotational asymmetry. This study confirms that GDNF can protect against 6-OHDA-induced impairments in complex as well as simple behaviours, and reinforces the use of EIAV-based vectors for the treatment of PD.

Amphetamine↗

PubMed2004

VEGF delivery with retrogradely transported lentivector prolongs survival in a mouse ALS model.

Amyotrophic lateral sclerosis (ALS) causes adult-onset, progressive motor neuron degeneration in the brain and spinal cord, resulting in paralysis and death three to five years after onset in most patients. ALS is still incurable, in part because its complex aetiology remains insufficiently understood. Recent reports have indicated that reduced levels of vascular endothelial growth factor (VEGF), which is essential in angiogenesis and has also been implicated in neuroprotection, predispose mice and humans to ALS. However, the therapeutic potential of VEGF for the treatment of ALS has not previously been assessed. Here we report that a single injection of a VEGF-expressing lentiviral vector into various muscles delayed onset and slowed progression of ALS in mice engineered to overexpress the gene coding for the mutated G93A form of the superoxide dismutase-1 (SOD1(G93A)) (refs 7-10), even when treatment was only initiated at the onset of paralysis. VEGF treatment increased the life expectancy of ALS mice by 30 per cent without causing toxic side effects, thereby achieving one of the most effective therapies reported in the field so far.

Amyotrophic Lateral Sclerosis↗

PubMed2004

Neuroprotection in a rat Parkinson model by GDNF gene therapy using EIAV vector.

Vectors based on lentiviruses are opening up new approaches for the treatment of neurodegenerative diseases. Currently, the equine infectious anaemia virus (EIAV) vector is one of the most attractive gene delivery systems with respect to neuronal tropism. The aim was to validate EIAV-lentiviral vectors as a gene delivery system for neurotrophic factor genes in an animal model of Parkinson's disease. EIAV carrying the glial cell line-derived neurotrophic factor (GDNF) gene was unilaterally injected into rat striatum and above the substantia nigra (SN). One week later, the rats received a 6-OHDA lesion into the ipsilateral striatum. GDNF delivery led to extensive expression of GDNF protein within the striatum. In addition, near complete protection against dopaminergic cell death was observed in the GDNF-treated group.

Animals↗

PubMed2004

Lentiviral vectors for treating and modeling human CNS disorders.

Vectors based on lentiviruses efficiently deliver genes into many different types of primary neurons from a broad range of species including man and the resulting gene expression is long term. These vectors are opening up new approaches for the treatment of neurological diseases such as Parkinson's disease (PD), Huntington's disease (HD), and motor neuron diseases (MNDs). Numerous animal studies have now been undertaken with these vectors and correction of disease models has been obtained. Lentiviral vectors also provide a new strategy for in vivo modeling of human diseases; for example, the lentiviral-mediated overexpression of mutated human alpha-synuclein or huntingtin genes in basal ganglia induces neuronal pathology in animals resembling PD and HD in man. These vectors have been refined to a very high level and can be produced safely for the clinic. This review will describe the general features of lentiviral vectors with particular emphasis on vectors derived from the non-primate lentivirus, equine infectious anemia virus (EIAV). It will then describe some key examples of genetic correction and generation of genetic animal models of neurological diseases. The prospects for clinical application of lentiviral vectors for the treatment of PD and MNDs will also be outlined.

Animals↗

PubMed2004

Local GDNF expression mediated by lentiviral vector protects facial nerve motoneurons but not spinal motoneurons in SOD1(G93A) transgenic mice.

Approximately 2% of amyotrophic lateral sclerosis (ALS) cases are associated with mutations in the cytosolic Cu/Zn superoxide dismutase 1 (SOD1) gene. Transgenic SOD1 mice constitute useful models of ALS to screen therapeutical approaches. Glial cell line-derived neurotrophic factor (GDNF) holds promises for the treatment of motoneuron disease. In the present study, GDNF expression in motoneurons of SOD1(G93A) transgenic mice was assessed by facial nucleus or intraspinal injection of lentiviral vectors (LV) encoding GDNF. We show that lentiviral vectors allow the expression for at least 12 weeks of GDNF that was clearly detected in motoneurons. This robust intraspinal expression did, however, not prevent the loss of motoneurons and muscle denervation of transgenic mice. In contrast, LV-GDNF induced a significant rescue of motoneurons in the facial nucleus and prevented motoneuron atrophy. The differential effect of GDNF on facial nucleus versus spinal motoneurons suggests different vulnerability of motoneurons in ALS.

Animals↗

PubMed2004

Transduction patterns of pseudotyped lentiviral vectors in the nervous system.

We have developed a non-primate-based lentiviral vector based on the equine infectious anemia virus (EIAV) for efficient gene transfer to the central and peripheral nervous systems. Previously we have demonstrated that pseudotyping lentiviral vectors with the rabies virus glycoprotein confers retrograde axonal transport to these vectors. In the present study we have successfully produced high-titer EIAV vectors pseudotyped with envelope glycoproteins from Rhabdovirus vesicular stomatitis virus (VSV) serotypes (Indiana and Chandipura strains); rabies virus [various Evelyn-Rokitnicki-Abelseth ERA strains and challenge virus standard (CVS)]; Lyssavirus Mokola virus, a rabies-related virus; and Arenavirus lymphocytic choriomeningitis virus (LCMV). These vectors were delivered to the striatum or spinal cord of adult rats or muscle of neonatal mice by direct injection. We report that the lentiviral vectors pseudotyped with envelopes from the VSV Indiana strain, wild-type ERA, and CVS strains resulted in strong transduction in the striatum, while Mokola- and LCMV-pseudotyped vectors exhibited moderate and weak transduction, respectively. Furthermore ERA- and CVS-pseudotyped lentiviral vectors demonstrated retrograde transport and expression in distal neurons after injection in brain, spinal cord, and muscle. The differences in transduction efficiencies and retrograde transport conferred by these envelope glycoproteins present novel opportunities in designing therapeutic strategies for different neurological diseases.

Animals↗

PubMed2004

Lentivector-mediated SMN replacement in a mouse model of spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a frequent recessive autosomal disorder. It is caused by mutations or deletion of the telomeric copy of the survival motor neuron (SMN) gene, leading to depletion in SMN protein levels. The treatment rationale for SMA is to halt or delay the degeneration of motor neurons, but to date there are no effective drug treatments for this disease. We have previously demonstrated that pseudotyping of the nonprimate equine infectious anemia virus (using the lentivector gene transfer system) with the glycoprotein of the Evelyn-Rokitnicki-Abelseth strain of the rabies virus confers retrograde axonal transport on these vectors. Here, we report that lentivector expressing human SMN was successfully used to restore SMN protein levels in SMA type 1 fibroblasts. Multiple single injections of a lentiviral vector expressing SMN in various muscles of SMA mice restored SMN to motor neurons, reduced motor neuron death, and increased the life expectancy by an average of 3 and 5 days (20% and 38%) compared with LacZ and untreated animals, respectively. Further extension of survival by SMN expression constructs will likely require a knowledge of when and/or where high levels of SMN are needed.

Animals↗

PubMed2002

Multicistronic lentiviral vector-mediated striatal gene transfer of aromatic L-amino acid decarboxylase, tyrosine hydroxylase, and GTP cyclohydrolase I induces sustained transgene expression, dopamine production, and functional improvement in a rat model of Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the selective loss of dopaminergic neurons in the substantia nigra. This loss leads to complete dopamine depletion in the striatum and severe motor impairment. It has been demonstrated previously that a lentiviral vector system based on equine infectious anemia virus (EIAV) gives rise to highly efficient and sustained transduction of neurons in the rat brain. Therefore, a dopamine replacement strategy using EIAV has been investigated as a treatment in the 6-hydroxydopamine (6-OHDA) animal model of PD. A self-inactivating EIAV minimal lentiviral vector that expresses tyrosine hydroxylase (TH), aromatic amino acid dopa decarboxylase (AADC), and GTP cyclohydrolase 1 (CH1) in a single transcription unit has been generated. In cultured striatal neurons transduced with this vector, TH, AADC, and CH1 proteins can all be detected. After stereotactic delivery into the dopamine-denervated striatum of the 6-OHDA-lesioned rat, sustained expression of each enzyme and effective production of catecholamines were detected, resulting in significant reduction of apomorphine-induced motor asymmetry compared with control animals (p < 0.003). Expression of each enzyme in the striatum was observed for up to 5 months after injection. These data indicate that the delivery of three catecholaminergic synthetic enzymes by a single lentiviral vector can achieve functional improvement and thus open the potential for the use of this vector for gene therapy of late-stage PD patients.

Animals↗