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Development of a liver-specific Tet-off AAV8 vector for improved safety of insulin gene therapy for diabetes.

ABSTRACT: BACKGROUND:Diabetes mellitus is caused by a partial or complete lack of insulin production in the body. We have previously shown that a single injection of an adeno-associated virus serotype 8 (AAV8) vector carrying a modified and codon optimized human insulin gene induced hepatic production of insulin and corrected streptozotocin (STZ)-induced diabetes in mice for more than 1 year. Insulin production was constitutive, analogous to long-acting insulin therapy. METHODS:We have developed a single AAV8 vector with a Tet-Off regulatable system as a safety mechanism to turn off insulin secretion should hypoglycaemia develop in vector-treated diabetic mice. We first transfected HepG2 cells or freshly isolated rat hepatocytes in vitro with the Tet-Off system (pAAV-Tetoffbidir -Alb-luc) regulating a luciferase reporter gene. We subsequently incorporated a furin-cleavable codon-optimised human proinsulin cDNA into pAAV-Tetoffbidir backbone to form the doxycycline inducible pAAV-Tetoffbidir -Alb-hINSco. RESULTS:Using STZ-induced diabetic mice, we were able to switch off insulin secretion repeatedly with doxycycline administration, and showed full restoration of insulin secretion on withdrawing doxycycline. CONCLUSIONS:The present study provides proof of concept that, under circumstances when inappropriate basal insulin secretion is a safety concern, insulin secretion from AAV8 gene therapy can be turned off reversibly with doxycycline.

SUBMITTER: Gan SU

PROVIDER: S-EPMC6590178 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Development of a liver-specific Tet-off AAV8 vector for improved safety of insulin gene therapy for diabetes.

Gan Shu Uin SU Fu Zhenying Z Sia Kian Chuan KC Kon Oi Lian OL Calne Roy R Lee Kok Onn KO

The journal of gene medicine 20190120 1

<h4>Background</h4>Diabetes mellitus is caused by a partial or complete lack of insulin production in the body. We have previously shown that a single injection of an adeno-associated virus serotype 8 (AAV8) vector carrying a modified and codon optimized human insulin gene induced hepatic production of insulin and corrected streptozotocin (STZ)-induced diabetes in mice for more than 1 year. Insulin production was constitutive, analogous to long-acting insulin therapy.<h4>Methods</h4>We have deve ...[more]

PMID: 30592790

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Project description:IntroductionOne consequence of population aging is an increase in the number of elderly patients with diabetes mellitus. These elderly patients often experience atherosclerotic complications, and diabetes prevention and management are strongly desired to promote health and reduce the financial burden on the healthcare system. In this study, we conducted an age-specific evaluation of the effectiveness and safety of comprehensive management with newly initiated insulin therapy over a 1-year period in elderly (≥65 years) compared with non-elderly (≤64 years) Japanese patients with uncontrolled diabetes [glycated hemoglobin (HbA1c) ≥ 8% for ≥ 3 months].MethodsThis retrospective single-center cohort study was conducted in Japan. We screened all outpatients with diabetes mellitus who visited the clinic for diabetes treatment between December 2006 and March 2011. Of these patients, 132 with type 2 diabetes who were newly initiated on insulin therapy for continued poor glycemic control and undergoing comprehensive management through self-monitoring of blood glucose (SMBG) were registered to the study.ResultsThirty-two of 132 registered patients were excluded from the analysis. Among the 100 patients (67 non-elderly, 33 elderly) included in the analysis, median age and proportion of male patients was 69 years and 66.7%, respectively, among the elderly, and 52 years and 68.7%, respectively, among the non-elderly patients. After initiation of insulin therapy, median HbA1c levels improved from 9.6% to 7.2% in elderly patients, and from 10.8% to 7.3% in non-elderly patients at baseline and 12 months. Severe hypoglycemic events were not observed in either patient group; however, uncontrolled diabetes was ongoing in 31.8% of non-elderly and 15.4% of elderly patients, and obesity was associated with poor glycemic control.ConclusionOur results indicate that the effectiveness and safety of newly initiated insulin therapy are similar between elderly and non-elderly Japanese patients with uncontrolled diabetes, and highlight the importance of comprehensive management using SMBG to avoid hypoglycemia. Better glycemic control supported by adequate intensive management is required to improve mortality and morbidity.

Project description:ObjectiveGremlin 1 (GREM1) is a secreted BMP2/4 inhibitor which regulates commitment and differentiation of human adipose precursor cells and prevents the browning effect of BMP4. GREM1 is an insulin antagonist and serum levels are high in type 2 diabetes (T2D). We here examined in vivo effects of AAV8 (Adeno-Associated Viral vectors of serotype eight) GREM 1 targeting the liver in mature mice to increase its systemic secretion and also, in a separate study, injected recombinant GREM 1 intraperitoneally. The objective was to characterize systemic effects of GREM 1 on insulin sensitivity, glucose tolerance, body weight, adipose cell browning and other local tissue effects.MethodsAdult mice were injected with AAV8 vectors expressing GREM1 in the liver or receiving regular intra-peritoneal injections of recombinant GREM1 protein. The mice were fed with a low fat or high fat diet (HFD) and followed over time.ResultsLiver-targeted AAV8-GREM1 did not alter body weight, whole-body glucose and insulin tolerance, or adipose tissue gene expression. Although GREM1 protein accumulated in liver cells, GREM1 serum levels were not increased suggesting that it may not have been normally processed for secretion. Hepatic lipid accumulation, inflammation and fibrosis were also not changed. Repeated intraperitoneal rec-GREM1 injections for 5 weeks were also without effects on body weight and insulin sensitivity. UCP1 was slightly but significantly reduced in both white and brown adipose tissue but this was not of sufficient magnitude to alter body weight. We validated that recombinant GREM1 inhibited BMP4-induced pSMAD1/5/9 in murine cells in vitro, but saw no direct inhibitory effect on insulin signalling and pAkt (ser 473 and thr 308) activation.ConclusionGREM1 accumulates intracellularly when overexpressed in the liver cells of mature mice and is apparently not normally processed/secreted. However, also repeated intraperitoneal injections were without effects on body weight and insulin sensitivity and adipose tissue UCP1 levels were only marginally reduced. These results suggest that mature mice do not readily respond to GREMLIN 1 but treatment of murine cells with GREMLIN 1 protein in vitro validated its inhibitory effect on BMP4 signalling while insulin signalling was not altered.

Project description:X-linked retinoschisis (XLRS) is a retinal disease caused by mutations in the gene encoding the protein retinoschisin (RS1) and one of the most common causes of macular degeneration in young men. Currently, no FDA-approved treatments are available for XLRS and a replacement gene therapy could provide a promising strategy. We have developed a novel gene therapy approach for XLRS, based on the administration of AAV8-scRS/IRBPhRS, an adeno-associated viral vector coding the human RS1 protein, via the intravitreal route. On the basis of our prior study in an Rs1-KO mouse, this construct transduces efficiently all the retinal layers, resulting in an RS1 expression similar to that observed in the wild-type and improving retinal structure and function. In support of a clinical trial, we carried out a study to evaluate the ocular safety of intravitreal administration of AAV8-scRS/IRBPhRS into 39 New Zealand White rabbits. Two dose levels of vector, 2e(10) and 2e(11) vector genomes per eye (vg/eye), were tested and ocular inflammation was monitored over a 12-week period by serial ophthalmological and histopathological analysis. A mild ocular inflammatory reaction, consisting mainly of vitreous infiltrates, was observed within 4 weeks from injection, in both 2e(10) and 2e(11) vg/eye groups and was likely driven by the AAV8 capsid. At 12-week follow-up, ophthalmological examination revealed no clinical signs of vitreitis in either of the dose groups. However, while vitreous inflammatory infiltrate was significantly reduced in the 2e(10) vg/eye group at 12 weeks, some rabbits in the higher dose group still showed persistence of inflammatory cells, histologically. In conclusion, intravitreal administration of AAV8-scRS/IRBPhRS into the rabbit eye produces a mild and transient intraocular inflammation that resolves, at a 2e(10) vg/eye dose, within 3 months, and does not cause irreversible tissue damages. These data support the initiation of a clinical trial of intravitreal administration of AAV8-scRS/IRBPhRS in XLRS patients.

Project description:IntroductionUrocortin 2 (Ucn2) is a 38-amino acid peptide of the corticotropin-releasing factor family. Intravenous (IV) delivery of an adeno-associated virus vector serotype 8 encoding Ucn2 (AAV8.Ucn2) increases insulin sensitivity and glucose disposal in mice with insulin resistance.ObjectiveTo determine the effects of Ucn2 on liver metabolome.MethodsSix-week-old C57BL6 mice were divided into normal chow (CHOW)-fed and high fat diet (HFD)-fed groups. The animals received saline, AAV8 encoding no gene (AAV8.Empt) or AAV8.Ucn2 (2x1013 genome copy/kg, IV injection). Livers were isolated from CHOW-fed and HFD-fed mice and analyzed by untargeted metabolomics. Group differences were statistically analyzed.ResultsIn CHOW-fed mice, AAV8.Ucn2 gene transfer (vs. saline) altered the metabolites in glycolysis, pentose phosphate, glycogen synthesis, glycogenolysis, and choline-folate-methionine signaling pathways. In addition, AAV8.Ucn2 gene transfer increased amino acids and peptides, which were associated with reduced protein synthesis. In insulin resistant (HFD-induced) mice, HFD (vs CHOW) altered 448 (112 increased and 336 decreased) metabolites and AAV8.Ucn2 altered 239 metabolites (124 increased and 115 reduced) in multiple pathways. There are 61 metabolites in 5 super pathways showed interactions between diet and AAV8.Ucn2 treatment. Among them, AAV8.Ucn2 gene transfer reversed HFD effects on 13 metabolites. Finally, plasma Ucn2 effects were determined using a 3-group comparison of HFD-fed mice that received AAV8.Ucn2, AAV.Empt or saline, where 18 metabolites that altered by HFD (15 increased and 3 decreased), but restored levels to that seen in CHOW-fed mice by increased plasma Ucn2.ConclusionsMetabolomics study revealed that AAV8.Ucn2 gene transfer, through increased plasma Ucn2, provided counter-HFD effects in restoring hepatic metabolites to normal levels, which could be the underlying mechanisms for Ucn2 effects on increasing glucose disposal and reducing insulin assistance.

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Development of a liver-specific Tet-off AAV8 vector for improved safety of insulin gene therapy for diabetes.

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Development of a liver-specific Tet-off AAV8 vector for improved safety of insulin gene therapy for diabetes.

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