Intracranial injections of lentiviral-NAGLU vector in MPS IIIB mice: effect of treatment on cytokines, neurotrophins and oxidative stress

Mucopolysaccharidosis type IIIB (MPS IIIB, Sanfilippo type B syndrome) is a lysosomal disorder caused by mutations in the gene encoding for alpha-N-acetylglucosaminidase (NAGLU), a glycosidase required for the degradation of heparan sulfate. The disease is characterized, clinically, by profound neurological deterioration with behavioral disturbances, but relatively mild somatic manifestations. At present, there is no treatment for MSP IIIB patients and the pathogenetic bases of the neurological disease remain unclear. We showed the efficacy of lentiviral-NAGLU vector mediated gene therapy in the visceral organs of the murine MPS IIIB model (1). More recently, we demonstrated, in the same model, that imbalance of cytokines, neurotrophins and oxidative stress can be involved in the pathogenesis of brain disease. In particular, Bdnf gene resulted to be down-regulated in the affected brains, while Cbln1, Ccl3, Casp11 and gp91phox, p67phox and p47phox (three components of the phagocyte NADPH oxidase) showed an increased expression in the affected mice vs normal controls (2). In the present study we evaluated the effect of intracranial injections of lentiviral-NAGLU vector in the MPS IIIB mice on cytokines, neurotrophins and oxidative stress. First, we used a lentiviral-GFP vector to evaluate the area of GFP gene transduction into the mice brain. The vector suspension was injected stereotactically in the right fimbria of 10-week-old animals, and treated mice were examined 1 month after treatment. Fluorescence microscopy for GFP expression on serial coronal sections showed positive cells for GFP in a large area surrounding the infusion site, and in some areas on the controlateral side of the brain. Subsequently, we injected the lentiviral-NAGLU vector in affected mice, obtaining a normal expression of active NAGLU enzyme throughout a large portion of the brain and a significant presence of vector genome copies. Real time RT PCR analysis performed on RNA from three regions (frontal, parietal and occipital) of brains from affected mice at one month from treatment, showed that Ccl3, Casp11 and gp91phox expression was unaffected; conversely, a normalization of neurotrophins Bdnf and Cbln1 was obtained. Our data suggest that gene therapy by intracranial injections of lentiviral-NAGLU vector can be effective for treatment of the brain pathology in the murine MPS IIIB model.