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Induction of Immune Tolerance to Foreign Protein via Adeno-Associated Viral Vector Gene Transfer in Mid-Gestation Fetal Sheep.

ABSTRACT: A major limitation to adeno-associated virus (AAV) gene therapy is the generation of host immune responses to viral vector antigens and the transgene product. The ability to induce immune tolerance to foreign protein has the potential to overcome this host immunity. Acquisition and maintenance of tolerance to viral vector antigens and transgene products may also permit repeat administration thereby enhancing therapeutic efficacy. In utero gene transfer (IUGT) takes advantage of the immunologic immaturity of the fetus to induce immune tolerance to foreign antigens. In this large animal study, in utero administration of AAV6.2, AAV8 and AAV9 expressing green fluorescent protein (GFP) to ~60 day fetal sheep (term: ~150 days) was performed. Transgene expression and postnatal immune tolerance to GFP and viral antigens were assessed. We demonstrate 1) hepatic expression of GFP 1 month following in utero administration of AAV6.2.GFP and AAV8.GFP, 2) in utero recipients of either AAV6.2.GFP or AAV8.GFP fail to mount an anti-GFP antibody response following postnatal GFP challenge and lack inflammatory cellular infiltrates at the intramuscular site of immunization, 3) a serotype specific anti-AAV neutralizing antibody response is elicited following postnatal challenge of in utero recipients of AAV6.2 or AAV8 with the corresponding AAV serotype, and 4) durable hepatic GFP expression was observed up to 6 months after birth in recipients of AAV8.GFP but expression was lost between 1 and 6 months of age in recipients of AAV6.2.GFP. The current study demonstrates, in a preclinical large animal model, the potential of IUGT to achieve host immune tolerance to the viral vector transgene product but also suggests that a single exposure to the vector capsid proteins at the time of IUGT is inadequate to induce tolerance to viral vector antigens.

SUBMITTER: Davey MG

PROVIDER: S-EPMC5283730 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Induction of Immune Tolerance to Foreign Protein via Adeno-Associated Viral Vector Gene Transfer in Mid-Gestation Fetal Sheep.

Davey Marcus G MG Riley John S JS Andrews Abigail A Tyminski Alec A Limberis Maria M Pogoriler Jennifer E JE Partridge Emily E Olive Aliza A Hedrick Holly L HL Flake Alan W AW Peranteau William H WH

PloS one 20170131 1

A major limitation to adeno-associated virus (AAV) gene therapy is the generation of host immune responses to viral vector antigens and the transgene product. The ability to induce immune tolerance to foreign protein has the potential to overcome this host immunity. Acquisition and maintenance of tolerance to viral vector antigens and transgene products may also permit repeat administration thereby enhancing therapeutic efficacy. In utero gene transfer (IUGT) takes advantage of the immunologic i ...[more]

PMID: 28141818

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Project description:BACKGROUND:Previous studies have shown a correlation between fluoride concentrations in urine and community water fluoride concentrations. However, there are no studies of the relationship between community water fluoridation, urine, serum, and amniotic fluid fluoride concentrations in pregnant women in the US. The aim of this study was to determine the relationship between maternal urine fluoride (MUF), maternal urine fluoride adjusted for specific gravity (MUFSG), maternal serum fluoride (MSF), amniotic fluid fluoride (AFF) concentrations during pregnancy, and community water fluoridation in Northern California. METHODS:Archived samples of urine, serum and amniotic fluid collected from second trimester pregnant women in Northern California from 47 different communities in Northern California and one from Montana (n =?48), were analyzed for fluoride using an ion specific electrode following acid microdiffusion. Women's addresses were matched to publicly reported water fluoride concentrations. We examined whether fluoride concentrations in biospecimens differed by fluoridation status of the community water, and determined the association between water fluoride concentrations and biospecimen fluoride concentrations using linear regression models adjusted for maternal age, smoking, Body Mass Index (BMI), race/ethnicity, and gestational age at sample collection. RESULTS:Fluoride concentrations in the community water supplies ranged from 0.02 to 1.00?mg/L. MUF, MSF , and AFF concentrations were significantly higher in pregnant women living in communities adhering to the U.S. recommended water fluoride concentration (0.7?mg/L), as compared with communities with less than 0.7?mg/L fluoride in drinking water. When adjusted for maternal age, smoking status, BMI, race/ethnicity, and gestational age at sample collection, a 0.1?mg/L increase in community water fluoride concentration was positively associated with higher concentrations of MUF (B?=?0.052, 95% CI:0.019,0.085), MUFSG (B = 0.028, 95% CI: -0.006, 0.062), MSF (B?=?0.001, 95% CI: 0.000, 0.003) and AFF (B?=?0.001, 95% CI: 0.000, 0.002). CONCLUSIONS:We found universal exposure to fluoride in pregnant women and to the fetus via the amniotic fluid. Fluoride concentrations in urine, serum, and amniotic fluid from women were positively correlated to public records of community water fluoridation. Community water fluoridation remains a major source of fluoride exposure for pregnant women living in Northern California.

Project description:BackgroundLeucine increases protein synthesis rates in postnatal animals and adults. Whether supplemental leucine has similar effects in the fetus has not been determined.ObjectiveTo determine the effect of a chronic leucine infusion on whole-body leucine oxidation and protein metabolic rates, muscle mass, and regulators of muscle protein synthesis in late gestation fetal sheep.MethodsCatheterized fetal sheep at ∼126 d of gestation (term = 147 d) received infusions of saline (CON, n = 11) or leucine (LEU; n = 9) adjusted to increase fetal plasma leucine concentrations by 50%-100% for 9 d. Umbilical substrate net uptake rates and protein metabolic rates were determined using a 1-13C leucine tracer. Myofiber myosin heavy chain (MHC) type and area, expression of amino acid transporters, and abundance of protein synthesis regulators were measured in fetal skeletal muscle. Groups were compared using unpaired t tests.ResultsPlasma leucine concentrations were 75% higher in LEU fetuses compared with CON by the end of the infusion period (P < 0.0001). Umbilical blood flow and uptake rates of most amino acids, lactate, and oxygen were similar between groups. Fetal whole-body leucine oxidation was 90% higher in LEU (P < 0.0005) but protein synthesis and breakdown rates were similar. Fetal and muscle weights and myofiber areas were similar between groups, however, there were fewer MHC type IIa fibers (P < 0.05), greater mRNA expression levels of amino acid transporters (P < 0.01), and a higher abundance of signaling proteins that regulate protein synthesis (P < 0.05) in muscle from LEU fetuses.ConclusionsA direct leucine infusion for 9 d in late gestation fetal sheep does not increase protein synthesis rates but results in higher leucine oxidation rates and fewer glycolytic myofibers. Increasing leucine concentrations in the fetus stimulates its own oxidation but also increases amino acid transporter expression and primes protein synthetic pathways in skeletal muscle.

Dataset Information

Induction of Immune Tolerance to Foreign Protein via Adeno-Associated Viral Vector Gene Transfer in Mid-Gestation Fetal Sheep.

Publications

Induction of Immune Tolerance to Foreign Protein via Adeno-Associated Viral Vector Gene Transfer in Mid-Gestation Fetal Sheep.

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