[Show abstract][Hide abstract] ABSTRACT: Gene therapy is entering the stage of initial clinical development to treat a growing number of inherited metabolic diseases. This review outlines the development of liver-directed gene therapy for diseases caused by deficiencies of enzymes that are primarily expressed in the liver and discusses the disorders that appear most promising for clinical translation.
Human Gene Therapy 04/2015; 26(4). DOI:10.1089/hum.2015.029 · 3.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recombinant vectors based on adeno-associated virus serotype 8 (AAV8) have been successfully used in the clinic and hold great promise for liver-directed gene therapy. Pre-existing immunity against AAV8 or the development of antibodies against the therapeutic transgene product might negatively affect the outcomes of gene therapy. In the prospect of an AAV8-mediated, liver-directed gene therapy clinical trial for Mucopolysaccharidosis VI (MPS VI), a lysosomal storage disorder due to arylsulfatase B (ARSB) deficiency, we investigated in a multiethnic cohort of MPS VI patients the prevalence of neutralizing antibodies (Nab) to AAV8 and the presence of ARSB cross-reactive immunologic material (CRIM), which will either affect the efficacy of gene transfer or the duration of phenotypic correction. Thirty-six MPS VI subjects included in the study harbored 45 (62.5%) missense, 13 (18%) nonsense, 9 (12.5%) frameshift (2 insertions and 7 deletions), and 5 (7%) splicing ARSB mutations. The detection of ARSB protein in twenty-four patients out of 34 (71%) was predicted by the type of mutations. Pre-existing Nab to AAV8 were undetectable in 19/33 (58%) analyzed patients. Twelve out of 31 patients (39%) tested were both negative for Nab to AAV8 and CRIM-positive. In conclusion, this study allows estimating the number of MPS VI patients eligible for a gene therapy trial by intravenous injections of AAV8.
Human Gene Therapy 02/2015; 26(3). DOI:10.1089/hum.2014.109 · 3.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pyruvate dehydrogenase complex (PDHC) is a key enzyme in metabolism linking glycolysis to tricarboxylic acid cycle and its activity is tightly regulated by phosphorylation catalyzed by four pyruvate dehydrogenase kinase (PDK) isoforms. PDKs are pharmacological targets for several human diseases including cancer, diabetes, obesity, heart failure, and inherited PDHC deficiency. We investigated the inhibitory activity of phenylbutyrate toward PDKs and found that PDK isoforms 1-to-3 are inhibited whereas PDK4 is unaffected. Moreover, docking studies revealed putative binding sites of phenylbutyrate on PDK2 and 3 that are located on different sites compared to dichloroacetate (DCA), a previously known PDK inhibitor. Based on these findings, we showed both in cells and in mice that phenylbutyrate combined to DCA results in greater increase of PDHC activity compared to each drug alone. These results suggest that therapeutic efficacy can be enhanced by combination of drugs increasing PDHC enzyme activity.
[Show abstract][Hide abstract] ABSTRACT: Helper-dependent adenoviral (HDAd) vectors can mediate long-term, high-level transgene expression from transduced hepatocytes without inducing chronic toxicity. However, vector therapeutic index is narrow because of a toxic acute response with potentially lethal consequences elicited by high vector doses. Kupffer cells (KCs) and liver sinusoidal endothelial cells (LSECs) are major barriers to efficient hepatocyte transduction. We investigated two small peptides (PP1 and PP2) developed by phage display to block scavenger receptor type A (SR-A) and scavenger receptor expressed on endothelial cells type I (SREC-I), respectively, for enhancement of HDAd-mediated hepatocyte transduction efficiency. Pre-incubation of J774A.1 macrophages with either PP1 or PP2 prior to HDAd infection significantly reduced viral vector uptake. In vivo, fluorochrome-conjugated PP1 and PP2 injected intravenously into mice co-localized with both CD68 and CD31 on KCs and LSECs, respectively. Compared with saline pre-treated animals, intravenous injections of both peptides prior to the injection of an HDAd resulted in up to 3.7-and 2.9-fold increase of hepatic transgene expression with PP1 and PP2, respectively. In addition to greater hepatocyte transduction, compared with control saline injected mice, pre-treatment with either peptide resulted in no increased levels of serum interleukin-6, the major marker of adenoviral vector acute toxicity. In summary, we developed small peptides that significantly increase hepatocyte transduction efficacy and improve HDAd therapeutic index with potential for clinical applications.
[Show abstract][Hide abstract] ABSTRACT: Retinal gene therapy with adeno-associated viral (AAV) vectors is safe and effective in humans. However, the limited cargo capacity of AAV prevents their use for therapy of those inherited retinopathies (IRs) due to mutations in large (>5kb) genes. Viral vectors derived from Adenovirus (Ad), Lentivirus (LV) and Herpesvirus (HV) can package large DNA sequences but do not target efficiently retinal photoreceptors (PRs) where the majority of genes responsible for IRs are expressed.
Here, we have evaluated the mouse retinal transduction profiles of vectors derived from 16 different Ad serotypes, 7 LV pseudotypes, and from a bovine HV. Most of the vectors tested transduced efficiently the retinal pigment epithelium (RPE). We found that LV-GP64 tends to transduce more PRs than the canonical LV-VSVG albeit this was restricted to a narrow region. We observed more extensive PR transduction with HdAd1, 2 and 5/F35++ than with LV, although none of them outperformed the canonical HdAd5 or matched the extension of PR transduction achieved with AAV2/8.
[Show abstract][Hide abstract] ABSTRACT: Copper is an essential yet toxic metal and its overload causes Wilson disease, a disorder due to mutations in copper transporter ATP7B. To remove excess copper into the bile, ATP7B traffics toward canalicular area of hepatocytes. However, the trafficking mechanisms of ATP7B remain elusive. Here, we show that, in response to elevated copper, ATP7B moves from the Golgi to lysosomes and imports metal into their lumen. ATP7B enables lysosomes to undergo exocytosis through the interaction with p62 subunit of dynactin that allows lysosome translocation toward the canalicular pole of hepatocytes. Activation of lysosomal exocytosis stimulates copper clearance from the hepatocytes and rescues the most frequent Wilson-disease-causing ATP7B mutant to the appropriate functional site. Our findings indicate that lysosomes serve as an important intermediate in ATP7B trafficking, whereas lysosomal exocytosis operates as an integral process in copper excretion and hence can be targeted for therapeutic approaches to combat Wilson disease.
[Show abstract][Hide abstract] ABSTRACT: Helper-dependent adenoviral (HDAd) vectors that are devoid of all viral coding sequences are promising non-integrating vectors for gene therapy because they efficiently transduce a variety of cell types in vivo, have a large cloning capacity, and drive long-term transgene expression without chronic toxicity. The main obstacle preventing clinical applications of HDAd vectors is the host innate inflammatory response against the vector capsid proteins that occurs shortly after intravascular vector administration and result in acute toxicity, the severity of which is dose dependent. Intense efforts have been focused on elucidating adenoviral vector–host interactions and the factors involved in the acute toxicity. This review focuses on the recent acquisition of data on such interactions and on strategies investigated to improve the therapeutic index of HDAd vectors.
[Show abstract][Hide abstract] ABSTRACT: Helper-dependent adenoviral vectors (HDAd) are attractive vectors for liver-directed gene therapy because they can drive sustained high levels of transgene expression without chronic toxicity. However, high vector doses are required to achieve efficient hepatic transduction by systemic delivery due to a nonlinear dose response. Unfortunately, such high doses result in systemic vector dissemination and dose-dependent acute toxicity with potential lethal consequences. We have previously shown in nonhuman primates that delivery of HDAd in surgically isolated livers resulted in a significantly higher hepatic transduction with reduced systemic vector dissemination compared to intravenous delivery liver and multi-year transgene expression. Encouraged by these data, we have now employed a surgical vector delivery method in the Gunn rat, an animal model for Crigler-Najjar syndrome. Following vector delivery into the surgically-isolated liver, we showed phenotypic correction at the low and clinically relevant vector dose of 1x1011 vp/kg. Correction of hyperbilirubinemia and increased glucuronidation of bilirubin in bile was achieved for up to 1 year after vector administration. Surgical delivery of the vector was well tolerated without signs of acute or chronic toxicity. This method of delivery could thereby be a safer alternative compared to liver transplantation for long-term treatment of Crigler-Najjar syndrome type I.
[Show abstract][Hide abstract] ABSTRACT: Myhre syndrome (MS, MIM 139210) is a connective tissue disorder that presents with short stature, short hands and feet, facial dysmorphic features, muscle hypertrophy, thickened skin, and deafness. Recurrent missense mutations in SMAD4 encoding for a transducer mediating transforming growth factor β (TGF-β) signaling are responsible for MS. We found that MS fibroblasts showed increased SMAD4 protein levels, impaired matrix deposition, and altered expression of genes encoding matrix metalloproteinases and related inhibitors. Increased TGF-β signaling and progression of aortic root dilation in Marfan syndrome can be prevented by the antihypertensive drug losartan, a TGF-β antagonists and angiotensin-II type 1 receptor blocker. Herein, we showed that losartan normalizes metalloproteinase and related inhibitor transcript levels and corrects the extracellular matrix deposition defect in fibroblasts from MS patients. The results of this study may pave the way toward therapeutic applications of losartan in MS.European Journal of Human Genetics advance online publication, 8 January 2014; doi:10.1038/ejhg.2013.283.
European journal of human genetics: EJHG 01/2014; 22(8). DOI:10.1038/ejhg.2013.283 · 4.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Rhabdomyolysis may result from various factors, namely trauma, exercise, medications, infections, endocrine disorders, congenital myopathies, and metabolic diseases.(1) Among the latter, mitochondrial fatty acid β-oxidation (FAO) defects frequently cause recurrent rhabdomyolysis. FAO disorders are recessively inherited and have a combined incidence of 1:9,300, estimated after implementation of newborn screening programs by tandem mass spectrometry (MS/MS).(2) Clinical manifestations of these disorders range from sudden infant death to Reye-like syndrome, nonketotic hypoglycemia, skeletal myopathy, peripheral neuropathy, and progressive cardiomyopathy. Here, we describe an 18-month-old child presenting with episodes of recurrent rhabdomyolysis related to mitochondrial trifunctional protein deficiency (MTPD), without additional manifestations of FAO defects. We discuss the diagnosis of MTPD and review the prognosis and treatments.
[Show abstract][Hide abstract] ABSTRACT: Research in autophagy continues to accelerate,(1) and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose.(2,3) There are many useful and convenient methods that can be used to monitor macroautophagy in yeast, but relatively few in other model systems, and there is much confusion regarding acceptable methods to measure macroautophagy in higher eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers of autophagosomes versus those that measure flux through the autophagy pathway; thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from fully functional autophagy that includes delivery to, and degradation within, lysosomes (in most higher eukaryotes) or the vacuole (in plants and fungi). Here, we present a set of guidelines for the selection and interpretation of the methods that can be used by investigators who are attempting to examine macroautophagy and related processes, as well as by reviewers who need to provide realistic and reasonable critiques of papers that investigate these processes. This set of guidelines is not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to verify an autophagic response.
[Show abstract][Hide abstract] ABSTRACT: Capillary malformation-arteriovenous malformation (CM-AVM) is an autosomal dominant disorder, caused by heterozygous RASA1 mutations, and manifesting multifocal capillary malformations and high risk for fast-flow lesions. A limited number of patients has been reported, raising the question of the phenotypic borders. We identified new patients with a clinical diagnosis of CM-AVM, and patients with overlapping phenotypes. RASA1 was screened in 261 index patients with: CM-AVM (n = 100), common capillary malformation(s) (port-wine stain; n = 100), Sturge-Weber syndrome (n = 37), or isolated arteriovenous malformation(s) (n = 24). Fifty-eight distinct RASA1 mutations (43 novel) were identified in 68 index patients with CM-AVM and none in patients with other phenotypes. A novel clinical feature was identified: cutaneous zones of numerous small white pale halos with a central red spot. An additional question addressed in this study was the "second-hit" hypothesis as a pathophysiological mechanism for CM-AVM. One tissue from a patient with a germline RASA1 mutation was available. The analysis of the tissue showed loss of the wild-type RASA1 allele. In conclusion, mutations in RASA1 underscore the specific CM-AVM phenotype and the clinical diagnosis is based on identifying the characteristic capillary malformations. The high incidence of fast-flow lesions warrants careful clinical and radiologic examination, and regular follow-up. This article is protected by copyright. All rights reserved.
Human Mutation 08/2013; 34(12). DOI:10.1002/humu.22431 · 5.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Crigler-Najjar syndrome type I is due to mutations of the uridine diphospho-glucuronosyl transferase 1A1 (UGT1A1) gene resulting in life-threatening increase of serum bilirubin. Life-long correction of hyperbilirubinemia was previously shown with intravenous injection of high doses of a helper-dependent adenoviral (HDAd) vector expressing UGT1A1 in the Gunn rat, the animal model of Crigler-Najjar syndrome. However, such high vector doses can activate an acute and potentially lethal inflammatory response with elevated serum interleukin-6 (IL-6). To overcome this obstacle, we investigated safety and efficacy of direct injections of low HDAd doses delivered directly into the liver parenchyma of Gunn rats. Direct hepatic injections performed by either laparotomy or by ultrasound-guided percutaneous injections were compared to the same doses given by intravenous injections. A greater reduction of hyperbilirubinemia and increased conjugated bilirubin in bile were achieved with 1x1011vp/kg by direct liver injections compared to intravenous injections. In sharp contrast to intravenous injections, direct hepatic injections did not raise serum IL-6 neither resulted in thrombocytopenia. In conclusion, ultrasound-guided percutaneous injection of HDAd vectors into liver parenchyma resulted in improved hepatocyte transduction and reduced toxicity compared to systemic injections and is clinically attractive for liver-directed gene therapy of Crigler-Najjar syndrome.
[Show abstract][Hide abstract] ABSTRACT: Helper-dependent adenoviral vectors (HDAd) have been shown to mediate considerably longer duration of transgene expression compared to first generation adenoviral vectors. We have previously shown that transgene expression from HDAd transduced hepatocytes can persist at high levels for up to 2.6 years in nonhuman primates following a single vector administration. Because duration of transgene expression and long-term toxicity are critical for risk:benefit assessment, we have continued to monitor these animals. We report here that transgene expression has persisted for the entire observation period of up to 7 years for all animals without long-term adverse effect. However, in all cases, transgene expression level slowly declined over time to less than 10% of peak values by the end of the observation period but remained 2.3 to 111-fold above baseline values. These results will provide important information for a more informed risk:benefit assessment prior to clinical application of HDAd.
Human gene therapy 07/2013; 24(8). DOI:10.1089/hum.2013.071 · 3.76 Impact Factor