Cerebrospinal fluid ß-glucocerebrosidase activity is reduced in parkinson's disease patients.

BACKGROUND: Reduced ß-glucocerebrosidase activity was observed in postmortem brains of both GBA1 mutation carrier and noncarrier Parkinson's disease patients, suggesting that lower ß-glucocerebrosidase activity is a key feature in the pathogenesis of PD. The objectives of this study were to confirm whether there is reduced ß-glucocerebrosidase activity in the CSF of GBA1 mutation carrier and noncarrier PD patients and verify if other lysosomal enzymes show altered activity in the CSF. METHODS: CSF ß-glucocerebrosidase, cathepsin D, and ß-hexosaminidase activities were measured in 79 PD and 61 healthy controls from the BioFIND cohort. The whole GBA1 gene was sequenced. RESULTS: Enzyme activities were normalized according to CSF protein content (specific activity). ß-glucocerebrosidase specific activity was significantly decreased in PD versus controls (-28%, P < 0.001). GBA1 mutations were found in 10 of 79 PD patients (12.7%) and 3 of 61 controls (4.9%). GBA1 mutation carrier PD patients showed significantly lower ß-glucocerebrosidase specific activity versus noncarriers. ß-glucocerebrosidase specific activity was also decreased in noncarrier PD patients versus controls (-25%, P < 0.001). Cathepsin D specific activity was lower in PD versus controls (-21%, P < 0.001). ß-Hexosaminidase showed a similar trend. ß-Glucocerebrosidase specific activity fairly discriminated PD from controls (area under the curve, 0.72; sensitivity, 0.67; specificity, 0.77). A combination of ß-glucocerebrosidase, cathepsin D, and ß-hexosaminidase improved diagnostic accuracy (area under the curve, 0.77; sensitivity, 0.71; specificity, 0.85). Lower ß-glucocerebrosidase and ß-hexosaminidase specific activities were associated with worse cognitive performance. CONCLUSIONS: CSF ß-glucocerebrosidase activity is reduced in PD patients independent of their GBA1 mutation carrier status. Cathepsin D and ß-hexosaminidase were also decreased. The possible link between altered CSF lysosomal enzyme activities and cognitive decline deserves further investigation. © 2017 International Parkinson and Movement Disorder Society.

Proteolytic degradation of neuropeptide Y (NPY) from head to toe: Identification of novel NPY-cleaving peptidases and potential drug interactions in CNS and Periphery.

The bioactivity of neuropeptide Y (NPY) is either N-terminally modulated with respect to receptor selectivity by dipeptidyl peptidase 4 (DP4)-like enzymes or proteolytic degraded by neprilysin or meprins, thereby abrogating signal transduction. However, neither the subcellular nor the compartmental differentiation of these regulatory mechanisms is fully understood. Using mass spectrometry, selective inhibitors and histochemistry, studies across various cell types, body fluids, and tissues revealed that most frequently DP4-like enzymes, aminopeptidases P, secreted meprin-A (Mep-A), and cathepsin D (CTSD) rapidly hydrolyze NPY, depending on the cell type and tissue under study. Novel degradation of NPY by cathepsins B, D, L, G, S, and tissue kallikrein could also be identified. The expression of DP4, CTSD, and Mep-A at the median eminence indicates that the bioactivity of NPY is regulated by peptidases at the interphase between the periphery and the CNS. Detailed ex vivo studies on human sera and CSF samples recognized CTSD as the major NPY-cleaving enzyme in the CSF, whereas an additional C-terminal truncation by angiotensin-converting enzyme could be detected in serum. The latter finding hints to potential drug interaction between antidiabetic DP4 inhibitors and anti-hypertensive angiotensin-converting enzyme inhibitors, while it ablates suspected hypertensive side effects of only antidiabetic DP4-inhibitors application. The bioactivity of neuropeptide Y (NPY) is either N-terminally modulated with respect to receptor selectivity by dipeptidyl peptidase 4 (DP4)-like enzymes or proteolytic degraded by neprilysin or meprins, thereby abrogating signal transduction. However, neither the subcellular nor the compartmental differentiation of these regulatory mechanisms is fully understood. Using mass spectrometry, selective inhibitors and histochemistry, studies across various cell types, body fluids, and tissues revealed that most frequently DP4-like enzymes, aminopeptidases P, secreted meprin-A (Mep-A), and cathepsin D (CTSD) rapidly hydrolyze NPY, depending on the cell type and tissue under study. Novel degradation of NPY by cathepsins B, D, L, G, S, and tissue kallikrein could also be identified. The expression of DP4, CTSD, and Mep-A at the median eminence indicates that the bioactivity of NPY is regulated by peptidases at the interphase between the periphery and the CNS. Detailed ex vivo studies on human sera and CSF samples recognized CTSD as the major NPY-cleaving enzyme in the CSF, whereas an additional C-terminal truncation by angiotensin-converting enzyme could be detected in serum. The latter finding hints to potential drug interaction between antidiabetic DP4 inhibitors and anti-hypertensive angiotensin-converting enzyme inhibitors, while it ablates suspected hypertensive side effects of only antidiabetic DP4-inhibitors application.

Variations in the response of interleukins in neurosurgical intensive care patients monitored using intracerebral microdialysis.

OBJECT: The aim of this study was to make a preliminary evaluation of whether microdialysis monitoring of cytokines and other proteins in severely diseased neurosurgical patients has the potential of adding significant information to optimize care, thus broadening the understanding of the function of these molecules in brain injury. METHODS: Paired intracerebral microdialysis catheters with high-cutoff membranes were inserted in 14 comatose patients who had been treated in a neurosurgical intensive care unit following subarachnoidal hemorrhage or traumatic brain injury. Samples were collected every 6 hours (for up to 7 days) and were analyzed at bedside for routine metabolites and later in the laboratory for interleukin (IL)-l and IL-6; in two patients, vascular endothelial growth factor and cathepsin-D were also checked. Aggregated microprobe data gave rough estimations of profound focal cytokine responses related to morphological tissue injury and to anaerobic metabolism that were not evident from the concomitantly collected cerebrospinal fluid data. Data regarding tissue with no macroscopic evidence of injury demonstrated that IL release not only is elicited in severely compromised tissue but also may be a general phenomenon in brains subjected to stress. Macroscopic tissue injury was strongly linked to IL-6 but not IL- lb activation. Furthermore, IL release seems to be stimulated by local ischemia. The basal tissue concentration level of IL-lb was estimated in the range of 10 to 150 pg/ml; for IL-6, the corresponding figure was 1000 to 20,000 pg/ml. CONCLUSIONS: Data in the present study indicate that catheters with high-cutoff membranes have the potential of expanding microdialysis to the study of protein chemistry as a routine bedside method in neurointensive care.

Comparative proteomics of cerebrospinal fluid in neuropathologically-confirmed Alzheimer's disease and non-demented elderly subjects.

OBJECTIVES: Diagnostic tests able to reveal Alzheimer's disease (AD) in living patients before cognitive ability is destroyed are urgently needed. Such tests must distinguish AD from other dementia causes, as well as differentiate subtle changes associated with normal aging from true pathology emergence. A single biomarker offering such diagnostic and prognostic capacities has eluded identification. Therefore, a valuable test for AD is likely to be based on a specific pattern of change in a set of proteins, rather than a single protein. METHODS: We examined pooled cerebrospinal fluid (CSF) samples obtained from neuropathologically-confirmed AD (n=43) and non-demented control subjects (n=43) using 2-dimensional gel electrophoresis (2DE) proteomic methodology to detect differentially expressed proteins. Proteins exhibiting expression level differences between the pools were recovered and identified using matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry. RESULTS: Five differentially-expressed proteins with potential roles in amyloid-beta metabolism and vascular and brain physiology [apolipoprotein A-1 (Apo A-1), cathepsin D (CatD), hemopexin (HPX), transthyretin (TTR), and two pigment epithelium-derived factor (PEDF) isoforms] were identified. Apo A-1, CatD and TTR were significantly reduced in the AD pool sample, while HPX and the PEDF isoforms were increased in AD CSF. DISCUSSION: These results suggest that multi-factor proteomic pattern analysis of the CSF may provide a means to diagnose and assess AD.

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.

Proteomic analysis of cerebrospinal fluid from patients with idiopathic temporal lobe epilepsy.

Proteomic analysis of cerebrospinal fluid (CSF) from patients with temporal lobe epilepsy (TLE) and controls was carried out using two-dimensional gel electrophoresis followed by liquid chromatography electrospray ionization tandem mass spectrometry. Five protein spots showed significant differential expression (p<0.05): vitamin D-binding protein (DBP) was elevated in the CSF of TLE patients whereas cathepsin D, apolipoprotein J, Fam3c, and superoxide dismutase 1 (SOD1) were decreased in the CSF of TLE patients. Additional six protein spots presented only in the CSF of epilepsy patients were identified as tetranectin (TN), talin-2, apolipoprotein E, immunoglobulin lambda light chain (IGL@), immunoglobulin kappa variable light chain 1-5 (IGKV1-5), and procollagen C-endopeptidase enhancer 1 (PCOLCE). Expression of DBP, SOD1 and talin-2 was validated by western blot. Our results may provide better understanding of the pathophysiologic mechanisms underlying epileptogenesis and possible epilepsy biomarkers.