Origin of α-mannosidase activity in CSF.

The α-mannosidase activity in human frontal gyrus, cerebrospinal fluid and plasma has been analyzed by DEAE-cellulose chromatography to investigate the origin of the α-mannosidase activity in cerebrospinal fluid (CSF). The profile of α-mannosidase isoenzymes obtained in CSF was similar to that in the frontal gyrus but different from that in human plasma. In particular the two characteristic peaks of lysosomal α-mannosidase, A and B, which have a pH-optimum of 4.5 and are found in human tissues, were present in both the frontal gyrus and CSF. In contrast the majority of α-mannosidase activity in human plasma was due to the so called intermediate form, which has a pH-optimum of 5.5. The results suggest that the intermediate form of α-mannosidase in plasma does not cross the blood-brain barrier and that the α-mannosidase activity present in the cerebrospinal fluid is of lysosomal type and of brain origin. Thus the α-mannosidase activity in cerebrospinal fluid might mirror the brain pathological changes linked to neurodegenerative disorders such as Parkinson's disease.

Clinical Improvement of Alpha-mannosidosis Cat Following a Single Cisterna Magna Infusion of AAV1.

Lysosomal storage diseases (LSDs) are debilitating neurometabolic disorders for most of which long-term effective therapies have not been developed. Gene therapy is a potential treatment but a critical barrier to treating the brain is the need for global correction. We tested the efficacy of cisterna magna infusion of adeno-associated virus type 1 (AAV1) expressing feline alpha-mannosidase gene in the postsymptomatic alpha-mannosidosis (AMD) cat, a homologue of the human disease. Lysosomal alpha-mannosidase (MANB) activity in the cerebrospinal fluid (CSF) and serum were increased above the control values in untreated AMD cats. Clinical neurological signs were delayed in onset and reduced in severity. The lifespan of the treated cats was significantly extended. Postmortem histopathology showed resolution of lysosomal storage lesions throughout the brain. MANB activity in brain tissue was significantly above the levels of untreated tissues. The results demonstrate that a single cisterna magna injection of AAV1 into the CSF can mediate widespread neuronal transduction of the brain and meaningful clinical improvement. Thus, cisterna magna gene delivery by AAV1 appears to be a viable strategy for treatment of the whole brain in AMD and should be applicable to many of the neurotropic LSDs as well as other neurogenetic disorders.

Factors influencing the measurement of lysosomal enzymes activity in human cerebrospinal fluid.

Measurements of the activities of lysosomal enzymes in cerebrospinal fluid have recently been proposed as putative biomarkers for Parkinson's disease and other synucleinopathies. To define the operating procedures useful for ensuring the reliability of these measurements, we analyzed several pre-analytical factors that may influence the activity of ß-glucocerebrosidase, α-mannosidase, ß-mannosidase, ß-galactosidase, α-fucosidase, ß-hexosaminidase, cathepsin D and cathepsin E in cerebrospinal fluid. Lysosomal enzyme activities were measured by well-established fluorimetric assays in a consecutive series of patients (n = 28) with different neurological conditions, including Parkinson's disease. The precision, pre-storage and storage conditions, and freeze/thaw cycles were evaluated. All of the assays showed within- and between-run variabilities below 10%. At -20°C, only cathepsin D was stable up to 40 weeks. At -80°C, the cathepsin D, cathepsin E, and ß-mannosidase activities did not change significantly up to 40 weeks, while ß-glucocerebrosidase activity was stable up to 32 weeks. The ß-galactosidase and α-fucosidase activities significantly increased (+54.9±38.08% after 4 weeks and +88.94±36.19% after 16 weeks, respectively). Up to four freeze/thaw cycles did not significantly affect the activities of cathepsins D and E. The ß-glucocerebrosidase activity showed a slight decrease (-14.6%) after two freeze/thaw cycles. The measurement of lysosomal enzyme activities in cerebrospinal fluid is reliable and reproducible if pre-analytical factors are accurately taken into consideration. Therefore, the analytical recommendations that ensue from this study may contribute to the establishment of actual values for the activities of cerebrospinal fluid lysosomal enzymes as putative biomarkers for Parkinson's disease and other neurodegenerative disorders.

Cerebrospinal fluid beta-glucocerebrosidase activity is reduced in Dementia with Lewy Bodies.

The autophagy-lysosomal degradation pathway plays a role in the onset and progression of neurodegenerative diseases. Clinical and genetic studies indicate that mutations of beta-glucocerebrosidase represent genetic risk factors for synucleinopathies, including Parkinson's Disease (PD) and Dementia with Lewy Bodies (DLB). We recently found a decreased activity of lysosomal hydrolases, namely beta-glucocerebrosidase, in cerebrospinal fluid of PD patients. We have thus measured the activity of these enzymes - alpha-mannosidase (EC 3.2.1.24), beta-mannosidase (EC 3.2.1.25), beta-glucocerebrosidase (EC 3.2.1.45), beta-galactosidase (EC 3.2.1.23) and beta-hexosaminidase (EC 3.2.1.52) - in cerebrospinal fluid of patients suffering from DLB, Alzheimer's Disease (AD), Fronto-Temporal Dementia (FTD) and controls. Alpha-mannosidase activity showed a marked decrease across all the pathological groups as compared to controls. Conversely, beta-glucocerebrosidase activity was selectively reduced in DLB, further suggesting that this enzyme might specifically be impaired in synucleinopathies.