Project description:Inducible degrader of low-density lipoprotein (LDL) receptor (Idol) is an E3 ubiquitin ligase coded by Idol, the target gene of liver X receptor (LXR), which primarily mediates the ubiquitination and lysosomal degradation of low-density lipoprotein receptor (LDLR). Previous studies from independent groups have shown that plasma cholesterol regulation by the LXR-Idol-LDLR axis is tissue- and species-specific, indicating that the precise molecular mechanism by which Idol modulates lipid metabolism has not been completely understood and needs to be further validated in other species. Hamster, a small rodent animal model expressing endogenous cholesterol ester transfer protein (CETP), possesses many metabolic characteristics that are different from mouse but similar to human. In this study, an Idol knockout (Idol-/-) hamster model was developed using CRISPR/Cas9 gene editing system to investigate the effect of Idol depletion on plasma lipid metabolism and atherosclerosis. Our results showed that there were no significant differences in hepatic LDLR protein and plasma cholesterol levels in Idol-/- hamsters compared with wild-type (WT) controls, which was consistent with the observation that LXR agonist treatment increased the expression of Idol mRNA in the small intestine but not in the liver of WT hamsters. However, we found that plasma triglyceride (TG) levels were significantly reduced in Idol-/- hamsters due to an enhancement of TG clearance. In addition, the morphological data demonstrated that inactivation of Idol significantly lowered plasma total cholesterol and TG levels and protected against spontaneous atherosclerotic lesions in aged LDLR knockout hamsters on a chow diet but had no effect on diet-induced atherosclerosis in hamsters lacking one copy of the Ldlr gene. In conclusion, our findings suggest that Idol can regulate plasma lipid metabolism and atherosclerosis independent of LDLR function.
Project description:Current approaches for hematopoietic stem cell gene therapy typically involve lentiviral gene transfer in tandem with a conditioning regimen to aid stem cell engraftment. Although many pseudotyped envelopes have the capacity to be immunogenic due to their viral origins, thus far immune responses against the most common envelope, vesicular stomatitis virus glycoprotein G (VSV-G), have not been reported in hematopoietic stem cell gene therapy trials. Herein, we report on two Fanconi anemia patients who underwent autologous transplantation of a lineage-depleted, gene-modified hematopoietic stem cell product without conditioning. We observed the induction of robust VSV-G-specific immunity, consistent with low/undetectable gene marking in both patients. Upon further interrogation, adaptive immune mechanisms directed against VSV-G were detected following transplantation in both patients, including increased VSV-G-specific T cell responses, anti-VSV-G immunoglobulin G (IgG), and cytotoxic responses that can specifically kill VSV-G-expressing target cell lines. A proportion of healthy controls also displayed preexisting VSV-G-specific CD4+ and CD8+ T cell responses, as well as VSV-G-specific IgG. Taken together, these data show that VSV-G-pseudotyped lentiviral vectors have the ability to elicit interfering adaptive immune responses in the context of certain hematopoietic stem cell transplantation settings.
Project description:RationaleThe E3 ubiquitin ligase inducible degrader of the low-density lipoprotein receptor (IDOL) triggers lysosomal degradation of the low-density lipoprotein receptor. The tissue-specific effects of the IDOL pathway on plasma cholesterol and atherosclerosis have not been examined.ObjectiveGiven that the liver is the primary determinant of plasma cholesterol levels, we sought to examine the consequence of effect of chronic liver-specific expression of a dominant-active form of IDOL in mice.Methods and resultsWe expressed a degradation-resistant, dominant-active form of IDOL (super IDOL [sIDOL]) in C57Bl/6J mice from the liver-specific albumin promoter (L-sIDOL transgenics). L-sIDOL mice were fed a Western diet for 20 or 30 weeks and then analyzed for plasma lipid levels and atherosclerotic lesion formation. L-sIDOL mice showed dramatic reductions in hepatic low-density lipoprotein receptor protein and increased plasma low-density lipoprotein cholesterol levels on both chow and Western diets. Moreover, L-sIDOL mice developed marked atherosclerotic lesions when fed a Western diet. Lesion formation in L-sIDOL mice was more robust than in apolipoprotein E*3 Leiden mice and did not require the addition of cholate to the diet. Western diet-fed L-sIDOL mice had elevated expression of liver X receptor target genes and proinflammatory genes in their aortas.ConclusionsLiver-specific expression of dominant-active IDOL is associated with hypercholesterolemia and a marked elevation in atherosclerotic lesions. Our results show that increased activity of the IDOL pathway in the liver can override other low-density lipoprotein receptor regulatory pathways leading to cardiovascular disease. L-sIDOL mice are a robust, dominantly inherited, diet-inducible model for the study of atherosclerosis.
Project description:Hemodialysis vascular access can develop venous neointimal hyperplasia (VNH) causing stenosis. Recent clinical and experimental data has demonstrated that there is increased expression of a disintegrin and metalloproteinase thrombospondin motifs-1 (ADAMTS-1) at site of VNH. The experiments outlined in the present paper were designed to test the hypothesis that targeting of the adventitia of the outflow vein of murine arteriovenous fistula (AVF) using a small hairpin RNA that inhibits ADAMTS-1 expression (LV-shRNA-ADAMTS-1) at the time of fistula creation will decrease VNH. At early time points, ADAMTS-1 expression was significantly decreased associated with a reduction in vascular endothelial growth factor-A (VEGF-A) and matrix metalloproteinase-9 (MMP-9) (LV-shRNA-ADAMTS-1 transduced vessels vs. controls). These changes in gene and protein expression resulted in favorable vascular remodeling with a significant increase in mean lumen vessel area, decrease in media/adventitia area, with a significant increase in TUNEL staining accompanied with a decrease in cellular proliferation accompanied with a reduction in CD68 staining. Collectively, these results demonstrate that ADAMTS-1 transduced vessels of the outflow vein of AVF have positive vascular remodeling.
Project description:Lentiviral vectors are a common tool used to introduce new and corrected genes into cell therapy products for treatment of human diseases. Although lentiviral vectors are ideal for delivery and stable integration of genes of interest into the host cell genome, they potentially pose risks to human health, such as integration-mediated transformation and generation of a replication competent lentivirus (RCL) capable of infecting non-target cells. In consideration of the latter risk, all cell-based products modified by lentiviral vectors and intended for patient use must be tested for RCL prior to treatment of the patient. Current Food and Drug Administration (FDA) guidelines recommend use of cell-based assays to this end, which can take up to 6 weeks for results. However, qPCR-based assays are a quick alternative for rapid assessment of RCL in products intended for fresh infusion. We describe here the development and qualification of a qPCR assay based on detection of envelope gene sequences (vesicular stomatitis virus G glycoprotein [VSV-G]) for RCL in accordance with Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines. Our results demonstrate the sensitivity, linearity, specificity, and reproducibility of detection of VSV-G sequences, with a low false-positive rate. These procedures are currently being used in our phase 1 clinical investigations.
Project description:BackgroundThe gene encoding the envelope of lentiviruses exhibits a considerable plasticity, particularly the region which encodes the surface (SU) glycoprotein. Interestingly, mutations do not appear uniformly along the sequence of SU, but they are clustered in restricted areas, called variable (V) regions, which are interspersed with relatively more stable regions, called constant (C) regions. We look for specific signatures of C/V regions, using hidden Markov models constructed with SU sequences of the equine, human, small ruminant and simian lentiviruses.ResultsOur models yield clear and accurate delimitations of the C/V regions, when the test set and the training set were made up of sequences of the same lentivirus, but also when they were made up of sequences of different lentiviruses. Interestingly, the models predicted the different regions of lentiviruses such as the bovine and feline lentiviruses, not used in the training set. Models based on composite training sets produce accurate segmentations of sequences of all these lentiviruses.ConclusionOur results suggest that each C/V region has a specific statistical oligonucleotide composition, and that the C (respectively V) regions of one of these lentiviruses are statistically more similar to the C (respectively V) regions of the other lentiviruses, than to the V (respectively C) regions of the same lentivirus.
Project description:BackgroundHendra virus (HeV) and Nipah virus (NiV) are newly emerged zoonotic paramyxoviruses discovered during outbreaks in Queensland, Australia in 1994 and peninsular Malaysia in 1998/9 respectively and classified within the new Henipavirus genus. Both viruses can infect a broad range of mammalian species causing severe and often-lethal disease in humans and animals, and repeated outbreaks continue to occur. Extensive laboratory studies on the host cell infection stage of HeV and NiV and the roles of their envelope glycoproteins have been hampered by their highly pathogenic nature and restriction to biosafety level-4 (BSL-4) containment. To circumvent this problem, we have developed a henipavirus envelope glycoprotein pseudotyped lentivirus assay system using either a luciferase gene or green fluorescent protein (GFP) gene encoding human immunodeficiency virus type-1 (HIV-1) genome in conjunction with the HeV and NiV fusion (F) and attachment (G) glycoproteins.ResultsFunctional retrovirus particles pseudotyped with henipavirus F and G glycoproteins displayed proper target cell tropism and entry and infection was dependent on the presence of the HeV and NiV receptors ephrinB2 or B3 on target cells. The functional specificity of the assay was confirmed by the lack of reporter-gene signals when particles bearing either only the F or only G glycoprotein were prepared and assayed. Virus entry could be specifically blocked when infection was carried out in the presence of a fusion inhibiting C-terminal heptad (HR-2) peptide, a well-characterized, cross-reactive, neutralizing human mAb specific for the henipavirus G glycoprotein, and soluble ephrinB2 and B3 receptors. In addition, the utility of the assay was also demonstrated by an examination of the influence of the cytoplasmic tail of F in its fusion activity and incorporation into pseudotyped virus particles by generating and testing a panel of truncation mutants of NiV and HeV F.ConclusionsTogether, these results demonstrate that a specific henipavirus entry assay has been developed using NiV or HeV F and G glycoprotein pseudotyped reporter-gene encoding retrovirus particles. This assay can be conducted safely under BSL-2 conditions and will be a useful tool for measuring henipavirus entry and studying F and G glycoprotein function in the context of virus entry, as well as in assaying and characterizing neutralizing antibodies and virus entry inhibitors.
Project description:RNA interference (RNAi) provides a versatile therapeutic approach via silencing of specific genes, particularly undruggable targets in cancer and other diseases. However, challenges in the delivery of small interfering RNA (siRNA) have hampered clinical translation. Polymeric or periodic short hairpin RNAs (p-shRNAs)-synthesized by enzymatic amplification of circular DNA-are a recent development that can potentially address these delivery barriers by showing improved stability and complexation to enable nanoparticle packaging. Here, we modify these biomacromolecules via structural and sequence engineering coupled with selective enzymatic digestion to generate an open-ended p-shRNA (op-shRNA) that is cleaved over ten times more efficiently to yield siRNA. The op-shRNA induces considerably greater gene silencing than p-shRNA in multiple cancer cell lines up to 9 days. Furthermore, its high valency and flexibility dramatically improve complexation with a low molecular weight polycation compared to monomeric siRNA. Thus, op-shRNA provides an RNAi platform that can potentially be packaged and efficiently delivered to disease sites with higher therapeutic efficacy.
Project description:Background and aimsFamilial hypercholesterolemia (FH) is a common inherited disorder of low density lipoprotein-cholesterol (LDL-C) metabolism. It is associated with higher risk of premature coronary heart disease. Around 60% of patients with a clinical diagnosis of FH do not have a detectable mutation in the genes causing FH and are most likely to have a polygenic cause for their raised LDL-C. We assessed the degree of preclinical atherosclerosis in treated patients with monogenic FH versus polygenic hypercholesterolemia.MethodsFH mutation testing and genotypes of six LDL-C-associated single nucleotide polymorphisms (SNPs) were determined using routine methods. Those with a detected mutation (monogenic) and mutation-negative patients with LDL-C SNP score in the top two quartiles (polygenic) were recruited. Carotid intima media thickness (IMT) was measured by B-mode ultrasound and the coronary artery calcium (CAC) score was performed in three lipid clinics in the UK and the Netherlands.Results86 patients (56 monogenic FH, 30 polygenic) with carotid IMT measurement, and 166 patients (124 monogenic, 42 polygenic) with CAC score measurement were examined. After adjustment for age and gender, the mean of all the carotid IMT measurements and CAC scores were significantly greater in the monogenic than the polygenic patients [carotid IMT mean (95% CI): 0.74 mm (0.7-0.79) vs. 0.66 mm (0.61-0.72), p = 0.038 and CAC score mean (95%): 24.5 (14.4-41.8) vs. 2.65 (0.94-7.44), p = 0.0004].ConclusionsIn patients with a diagnosis of FH, those with a monogenic cause have a higher severity of carotid and coronary preclinical atherosclerosis than those with a polygenic aetiology.
Project description:Venous neointimal hyperplasia (VNH) causes hemodialysis vascular access failure. Here we tested whether VNH formation occurs in part due to local vessel hypoxia caused by surgical trauma to the vasa vasorum of the outflow vein at the time of arteriovenous fistula placement. Selective targeting of the adventitia of the outflow vein at the time of fistula creation was performed using a lentivirus-delivered small-hairpin RNA that inhibits VEGF-A expression. This resulted in significant increase in mean lumen vessel area, decreased media/adventitia area, and decreased constrictive remodeling with a significant increase in apoptosis (increase in caspase 3 activity and TUNEL staining) accompanied with decreased cellular proliferation and hypoxia-inducible factor-1α at the outflow vein. There was significant decrease in cells staining positive for α-smooth muscle actin (a myofibroblast marker) and VEGFR-1 expression with a decrease in MMP-2 and MMP-9. These results were confirmed in animals that were treated with humanized monoclonal antibody to VEGF-A with similar results. Since hypoxia can cause fibroblast to differentiate into myofibroblasts, we silenced VEGF-A gene expression in fibroblasts and subjected them to hypoxia. This decreased myofibroblast production, cellular proliferation, cell invasion, MMP-2 activity, and increased caspase 3. Thus, VEGF-A reduction at the time of arteriovenous fistula placement results in increased positive vascular remodeling.