RESUMO
Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare autosomal recessive disease that impairs synthesis of dopamine and serotonin. Children with AADC deficiency exhibit severe motor, behavioral, and autonomic dysfunctions. We previously generated an IVS6+4A>T knock-in mouse model of AADC deficiency (Ddc(KI) mice) and showed that gene therapy at the neonatal stage can rescue this phenotype. In the present study, we extended this treatment to systemic therapy on young mice. After intraperitoneal injection of AADC viral vectors into 7-day-old Ddc(KI) mice, the treated mice exhibited improvements in weight gain, survival, motor function, autonomic function, and behavior. The yfAAV9/3-Syn-I-mAADC-treated mice showed greater neuronal transduction and higher brain dopamine levels than AAV9-CMV-hAADC-treated mice, whereas AAV9-CMV-hAADC-treated mice exhibited hyperactivity. Therefore, neurotransmitter-deficient animals can be rescued at a young age using systemic gene therapy, although a vector for preferential neuronal expression may be necessary to avoid hyperactivity caused by this treatment.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/genética , Erros Inatos do Metabolismo dos Aminoácidos/terapia , Descarboxilases de Aminoácido-L-Aromático/deficiência , Descarboxilases de Aminoácido-L-Aromático/genética , Terapia Genética , Neurônios/metabolismo , Neurotransmissores/deficiência , Erros Inatos do Metabolismo dos Aminoácidos/diagnóstico por imagem , Erros Inatos do Metabolismo dos Aminoácidos/mortalidade , Erros Inatos do Metabolismo dos Aminoácidos/fisiopatologia , Animais , Descarboxilases de Aminoácido-L-Aromático/metabolismo , Comportamento Animal , Pressão Sanguínea/genética , Encéfalo/metabolismo , Dependovirus/genética , Modelos Animais de Doenças , Dopamina/metabolismo , Ativação Enzimática , Fluordesoxiglucose F18 , Expressão Gênica , Terapia Genética/métodos , Vetores Genéticos/administração & dosagem , Vetores Genéticos/genética , Frequência Cardíaca , Imuno-Histoquímica , Camundongos , Camundongos Transgênicos , Atividade Motora , Especificidade de Órgãos/genética , Tomografia por Emissão de Pósitrons , Transdução Genética , Aumento de Peso/genéticaRESUMO
Dopamine and serotonin are produced by distinct groups of neurons in the brain, and gene therapies other than direct injection have not been attempted to correct congenital deficiencies in such neurotransmitters. In this study, we performed gene therapy to treat knock-in mice with dopamine and serotonin deficiencies caused by a mutation in the aromatic L-amino acid decarboxylase (AADC) gene (Ddc(KI) mice). Intracerebral ventricular injection of neonatal mice with an adeno-associated virus (AAV) serotype 9 (AAV9) vector expressing the human AADC gene (AAV9-hAADC) resulted in widespread AADC expression in the brain. Without treatment, 4-week-old Ddc(KI) mice exhibited whole-brain homogenate dopamine and serotonin levels of 25% and 15% of normal, respectively. After gene therapy, the levels rose to 100% and 40% of normal, respectively. The gene therapy improved the growth rate and survival of Ddc(KI) mice and normalized their hindlimb clasping and cardiovascular dysfunctions. The behavioral abnormalities of the Ddc(KI) mice were partially corrected, and the treated Ddc(KI) mice were slightly more active than normal mice. No immune reactions resulted from the treatment. Therefore, a congenital neurotransmitter deficiency can be treated safely through inducing widespread expression of the deficient gene in neonatal mice.