Astrocytes are involved in key physiological brain processes, such as glutamatergic transmission and energy metabolism, often altered in neurodegenerative diseases. Targeted gene expression in astrocytes is needed to assess the contribution of these cells to physiological processes and for the development of new therapeutic strategies. However, most of the viral vectors currently used for gene transfer in the central nervous system (CNS) are highly neurotropic. We used mokola pseudotyping to shift the tropism of lentiviral vectors toward astrocytes and a detargeting strategy with miRNA to eliminate residual expression in neuronal cells. In primary cultures, we showed that incorporating target sequences for the neuron-specific miR124 effectively abolished transgene expression in neurons post-transcriptionally. Targeted expression of the LacZ reporter gene in astrocytes was achieved in the hippocampus, striatum, and cerebellum of the adult mouse in vivo. As a proof-of-principle, this new lentiviral vector was used to either overexpress or downregulate (RNA interference) the glial glutamate transporter GLAST into striatal astrocytes in vivo. These vectors provide new opportunities for cell type-specific gene transfer in the CNS.

High energy demands of neurons make them vulnerable to adverse effects of energy impairment. Recently, astrocytes were shown to regulate the flux of energy substrates to neurons. In pathological situations, astrocytes are activated but the consequences on brain energy metabolism are still poorly characterized. We found that local lentiviral-mediated gene transfer of ciliary neurotrophic factor (CNTF), a cytokine known to activate astrocytes, induced a stable decrease in the glycolytic flux in the rat striatum in vivo as measured by 2-[18 F]-2-deoxy-D-glucose autoradiography and micro-positron emission tomography imaging. The activity of the mitochondrial complex IV enzyme cytochrome oxidase was not modified, suggesting maintenance of downstream oxidative steps of energy production. CNTF significantly increased the phosphorylation level of the intracellular energy sensor AMP-activated protein kinase (AMPK), supporting a specific reorganization of brain energy pathways. Indeed, we found that different key enzymes/transporters of fatty acids ␤-oxidation and ketolysis were overexpressed by CNTF-activated astrocytes within the striatum. In primary striatal neuron/astrocyte mixed cultures exposed to CNTF, the AMPK pathway was also activated, and the rate of oxidation of fatty acids and ketone bodies was significantly enhanced. This metabolic plasticity conferred partial glial and neuronal protection against prolonged palmitate exposure and glycolysis inhibition. We conclude that CNTF-activated astrocytes may have a strong protective potential to face severe metabolic insults.

Introduction: Sjögren’s syndrome (SS) is a chronic inflammatory auto-immune disease of the exocrine glands which incidence increases with age. Sex ratio is 9.9 female for 1 male. Observation: A 67-year-old female patient presented for xerostomia leading to major functional impairment. The medical history of the patient was pulmonary sarcoidosis, with join and adenoid involvement, considered as cured; left partial parotidectomy, with a diagnosis of acinous carcinoma, followed 7 years later by a total parotidectomy due to tumor recurrence, and followed by external radiotherapy (70 Gy). Arterial hypertension, hypothyroïditis and diabetes mellitus were also noticed. She reported xerostomia and xerophtalmia. Seric anti-SSA antibodies were positive and histologic findings were compatible with SS. Commentaries: Despite other co-morbidities, the diagnosis was hidden by previous parotidectomy and cervical radiotherapy. Thus, SS should not be underdiagnosed in patients with complex medical history.

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