A prospective one-year natural history study of mucopolysaccharidosis types IIIA and IIIB: Implications for clinical trial design.

Mucopolysaccharidosis type III is a group of four autosomal recessive enzyme deficiencies leading to tissue accumulation of heparan sulfate. Central nervous system disease is prominent, with initial normal development followed by neurocognitive decline leading to death. In order to define outcome measures suitable for gene transfer trials, we prospectively assessed disease progression in MPS IIIA and IIIB subjects >2years old at three time points over one year (baseline, 6 and 12months). Fifteen IIIA (9 male, 6 female; age 5.0±1.9years) and ten IIIB subjects (8 male, 2 female; age 8.6±3years) were enrolled, and twenty subjects completed assessments at all time points. Cognitive function as assessed by Mullen Scales maximized at the 2.5 to 3year old developmental level, and showed a significant age-related decline over a 6month interval in three of five subdomains. Leiter nonverbal IQ (NVIQ) standard scores declined toward the test floor in the cohort by 6 to 8years of age, but showed significant mean declines over a 6month interval in those <7years old (p=0.0029) and in those with NVIQ score≥45 (p=0.0313). Parental report of adaptive behavior as assessed by the Vineland-II composite score inversely correlated with age and showed a significant mean decline over 6month intervals (p=0.0004). Abdominal MRI demonstrated increased volumes in liver (mean 2.2 times normal) and spleen (mean 1.9 times normal) without significant change over one year; brain MRI showed ventriculomegaly and loss of cortical volume in all subjects. Biochemical measures included urine glycosaminoglycan (GAG) levels, which although elevated showed a decline correlating with age (p<0.0001) and approached normal values in older subjects. CSF protein levels were elevated in 32% at enrollment, and elevations of AST and ALT were frequent. CSF enzyme activity levels for either SGSH (in MPS IIIA subjects) or NAGLU (in MPS IIIB) significantly differed from normal controls. Several other behavioral or functional measures were found to be uninformative in this population, including timed functional motor tests. Our results suggest that cognitive development as assessed by the Mullen and Leiter-R and adaptive behavior assessment by the Vineland parent interview are suitable functional outcomes for interventional trials in MPS IIIA or IIIB, and that CSF enzyme assay may be a useful biomarker to assess central nervous system transgene expression in gene transfer trials.

Determination of the role of injection site on the efficacy of intra-CSF enzyme replacement therapy in MPS IIIA mice.

MPS IIIA is an inherited neurodegenerative lysosomal storage disorder characterized by cognitive impairment, sleep-wake cycle disturbance, speech difficulties, eventual mental regression and early death. Neuropathological changes include accumulation of heparan sulfate and glycolipids, neuroinflammation and degeneration. Pre-clinical animal studies indicate that replacement of the deficient enzyme, sulfamidase, via intra-cerebrospinal fluid (CSF) injection is a clinically-relevant treatment approach, reducing neuropathological changes and improving symptoms. Given that there are several routes of administration of enzyme into the CSF (intrathecal lumbar, cisternal and ventricular), determining the effectiveness of each injection strategy is crucial in order to provide the best outcome for patients. We delivered recombinant human sulfamidase (rhSGSH) to a congenic mouse model of MPS IIIA via each of the three routes. Mice were euthanized 24h or one-week post-injection; the distribution of enzyme within the brain and spinal cord parenchyma was investigated, and the impact on primary substrate levels and other pathological lesions determined. Both ventricular and cisternal injection of rhSGSH enable enzyme delivery to brain and spinal cord regions, with the former mediating large, statistically significant decreases in substrate levels and reducing microglial activation. The single lumbar CSF infusion permitted more restricted enzyme delivery, with no reduction in substrate levels and little change in other disease-related lesions in brain tissue. While the ventricular route is the most invasive of the three methods, this strategy may enable the widest distribution of enzyme within the brain, and thus requires further exploration.

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 biomarker candidates of schizophrenia: where do we stand?

Here, we review the cerebrospinal fluid (CSF) candidate markers with regard to their clinical relevance as potential surrogates for disease activity, prognosis assessment, and predictors of treatment response. We searched different online databases such as MEDLINE and EMBASE for studies on schizophrenia and CSF. Initial studies on cerebrospinal fluid in patients with schizophrenia revealed increased brain-blood barrier permeability with elevated total protein content, increased CSF-to-serum ratio for albumin, and intrathecal production of immunoglobulins in subgroups of patients. Analyses of metabolites in CSF suggest alterations within glutamatergic neurotransmission as well as monoamine and cannabinoid metabolism. Decreased levels of brain-derived neurotrophic factor and nerve growth factor in CSF of first-episode patients with schizophrenia reported in recent studies point to a dysregulation of neuroprotective and neurodevelopmental processes. Still, these findings must be considered as non-specific. A more profound characterization of the particular psychopathological profiles, the investigation of patients in the prodromal phase or within the first episode of schizophrenia promoting longitudinal investigations, implementation of different approaches of proteomics, and rigorous adherence to standard procedures based on international CSF guidelines are necessary to improve the quality of CSF studies in schizophrenia, paving the way for identification of syndrome-specific biomarker candidates.

Effect of cisternal sulfamidase delivery in MPS IIIA Huntaway dogs--a proof of principle study.

Mucopolysaccharidosis type IIIA (MPS IIIA) results from lack of functional sulfamidase (SGSH), a lysosomal enzyme. Its substrate, heparan sulfate, and other secondarily-stored compounds subsequently accumulate primarily within the central nervous system (CNS), resulting in progressive mental deterioration and early death. Presently there is no treatment. As a potential therapeutic strategy, recombinant human sulfamidase (rhSGSH) was administered into the CSF (via the cerebellomedullary cistern) of three adult MPS IIIA dogs either twice with a 4 day interval, or weekly for up to 4 weeks. The dogs were euthanased 24 h post-injection along with one untreated unaffected and two MPS IIIA controls. We have examined the three dimensional pattern of distribution of enzyme in the CNS and its ability to reduce primary substrate storage. High concentrations of rhSGSH protein, with up to 39-fold normal enzyme activity levels were detected within widespread areas of the CNS. RhSGSH protein was also detectable by immunohistochemistry in neurons and glia in all three enzyme-treated dogs. In both weekly-treated dogs, relative levels of a heparan sulfate-derived disaccharide, measured using tandem mass spectrometry, were lower in many brain regions when compared to untreated MPS IIIA controls. A moderately severe meningitis was also present as well as antibodies to rhSGSH in CSF/plasma. These findings demonstrate proof of principle that MPS IIIA can be treated by intracisternal enzyme replacement warranting further experiments in animals tolerant to rhSGSH. This enzyme delivery method may represent a means of treating neuropathology in MPS IIIA and other lysosomal storage disorders affecting the CNS.

Increased activity of lysosomal acid hydrolases in the cell-free cerebrospinal fluid of bacterial meningitis.

Because inflammation could affect lysosomal enzyme trafficking, resulting in increased enzyme release from the cells, tissue necrosis, or altered blood- and the brain-cerebrospinal fluid (CSF) barrier, the activity of four lysosomal enzymes in the cell-free CSF of 34 patients with bacterial meningitis, 20 with aseptic meningitis, and 39 control subjects was measured. Activities are expressed in nanomoles of 4-methylumbelliferone mL/h. The median beta-hexosaminidase A activity in bacterial meningitis was 313, in aseptic meningitis it was 173, and in the control subjects it was 175, the median beta-hexosaminidase B activity was 417, 165, and 120; the median alpha-mannosidase activity was 171, 124, and 113; and the median beta-glucuronidase activity was 133.7, 14.3, and 10.0, respectively. The difference of the activities of the four enzymes measured between the bacteria meningitis and the controls is significant (p < 0.000). Also significant is the difference between bacterial and aseptic meningitis (p = 0.005 to < 0.000), but it is not significant between aseptic and control subjects. Both the sensitivity and specificity of the beta-glucuronidase activity between bacterial meningitis and control subjects were 100%, whereas the corresponding values between bacterial and aseptic meningitis were 100% and 90%, respectively. No significant correlation was observed between the activities of the enzymes measured and the number of the polymorphonuclear leukocytes or other laboratory characteristics of the CSF. The increased lysosomal enzyme activities in the CSF of patients with meningitis may result from diffusion across the blood-CSF or the brain-CSF barrier or from enzyme leakage through the cell membranes.

Stability of enzymes of lysosomal origin in human cerebrospinal fluid.

The optimal assay conditions and the stability of the following enzymes of lysosomal origin in human cerebrospinal fluid (CSF) were studied: acid phosphatase, beta-D-N-acetylglucosaminidase, alpha-D-galactosidase, beta-D-galactosidase, alpha-D-glucosidase, beta-D-glucosidase, alpha-L-fucosidase, alpha-D-mannosidase, beta-D-glucuronidase. The microsomal alpha-D-mannosidase, pH 5.7, was used as a reference non-lysosomal glycohydrolase. All the examined enzymes, with the only exception of beta-D-glucuronidase, underwent a more or less rapid loss of activity upon CSF storage in the temperature range from 37 degrees C to -80 degrees C. Storage in liquid nitrogen (-196 degrees C) was the only condition in which full activity for all tested enzymes was maintained for at least 15 days. Addition of human serum albumin to CSF, immediately after withdrawal, had a double effect in favouring enzyme stabilization and causing enzyme activation in some cases, and enzyme inhibition in others. Using conditions warranting enzyme stability the fluorimetric methods for lysosomal enzymes determination in cerebrospinal fluid appear to be highly reproducible (CV less than 5%) and simple enough for routine use.

CSF lysosomal hydrolase activity as an aid in the diagnosis of bacterial meningitis.

The activity of the lysosomal enzymes acid phosphatase, beta-glucuronidase, alpha-mannosidase and hexosaminidase were determined in CSF obtained from patients with proven bacterial meningitis and from patients with various other diagnoses. The mean value for CSF beta-glucuronidase from bacterial meningitis was elevated 73-fold when compared to the aggregate mean of all control groups. Acid phosphatase and alpha-mannosidase means were 26-fold and 33-fold elevated respectively while hexosaminidase was threefold elevated. Measurement of CSF acid phosphatase and beta-glucuronidase should prove a rapid useful test in establishing the diagnosis of bacterial meningitis. Chromatography of CSF samples on DEAE Sephadex allowed the resolution of hexosaminidase and beta-glucuronidase into individual isozymes. The ratio of hexosaminidase A to hexosaminidase B was generally higher in CSF from patients with bacterial meningitis but was very variable. The isozyme distribution for beta-glucuronidase was identical to that found in serum and no differences in pattern were found between patients and control subjects.

Postmortem sera and cerebrospinal fluid enzymes.

Antemortem and postmortem sera from 60 dogs were evaluated for lipase, amylase, alkaline phosphatase, gamma-glutamyltransferase, and alanine aminotransferase (AAT); cerebrospinal fluid was examined for AAT and alkaline phosphatase. The postmortem intervals were 3, 6, 12, 24, and 48 h at temperatures of 4, 20, and 37 degrees C. Amylase levels remained stable at 4 and 20 degrees C and may be beneficial for diagnosing pancreatitis. Lipase levels may be useful as an adjunct to amylase values. Serum alkaline phosphatase values increased with postmortem interval; values were higher at 37 degrees C than at 4 degrees C. Other enzymes were of little value for diagnosis.

Diagnostic value of determinations of lysosomal hydrolases in CSF of patients with neurological diseases.

The activities of four lysosomal acid hydrolases, beta-galactosidase, alpha-mannosidase at pH 4.5 and 5.5, N-acetyl-beta-glucosaminidase, and acid phosphatase, have been measured in serum and cerebrospinal fluid from 179 patients with different neurological diseases and from 20 healthy controls. In patients with tumours, decreased activity of beta-galactosidase was found in both serum and cerebrospinal fluid, and in patients with multiple sclerosis and collagen diseases, decreased activities of beta-galactosidase and N-acetyl-beta-glucosaminidase were found in cerebrospinal fluid. The variations of enzyme activities were great between the individual patients even with these groups and analysis of lysosomal enzymes seems to have a very poor clinical value.