Acetylcholinesterase and butyrylcholinesterase activities in cerebrospinal fluid from different levels of the neuraxis of patients with dementia of the Alzheimer type

MS-based glycomics: An analytical tool to assess nervous system diseases

Neurological diseases affect millions of peopleochemistryorldwide and are continuously increasing due to the globe's aging population. Such diseases affect the nervous system and are characterized by a progressive decline in brain function and progressive cognitive impairment, decreasing the quality of life for those with the disease as well as for their families and loved ones. The increased burden of nervous system diseases demands a deeper insight into the biomolecular mechanisms at work during disease development in order to improve clinical diagnosis and drug design. Recently, evidence has related glycosylation to nervous system diseases. Glycosylation is a vital post-translational modification that mediates many biological functions, and aberrant glycosylation has been associated with a variety of diseases. Thus, the investigation of glycosylation in neurological diseases could provide novel biomarkers and information for disease pathology. During the last decades, many techniques have been developed for facilitation of reliable and efficient glycomic analysis. Among these, mass spectrometry (MS) is considered the most powerful tool for glycan analysis due to its high resolution, high sensitivity, and the ability to acquire adequate structural information for glycan identification. Along with MS, a variety of approaches and strategies are employed to enhance the MS-based identification and quantitation of glycans in neurological samples. Here, we review the advanced glycomic tools used in nervous system disease studies, including separation techniques prior to MS, fragmentation techniques in MS, and corresponding strategies. The glycan markers in common clinical nervous system diseases discovered by utilizing such MS-based glycomic tools are also summarized and discussed.

Effects of Peroral Omega-3 Fatty Acid Supplementation on Cerebrospinal Fluid Biomarkers in Patients with Alzheimer's Disease: A Randomized Controlled Trial-The OmegAD Study

BACKGROUND

Studies have suggested a connection between a decrease in the levels of polyunsaturated fatty acids (PUFAs) and Alzheimer's disease (AD). We aimed to assess the effect of supplementation with omega-3 fatty acids (n-3 FAs) on biomarkers analyzed in the cerebrospinal fluid (CSF) of patients diagnosed with AD.

OBJECTIVE

To investigate the effects of daily supplementation with 2.3 g of PUFAs in AD patients on the biomarkers in CSF described below. We also explored the possible correlation between these biomarkers and the performance in the cognitive test Mini-Mental State Examination (MMSE).

METHODS

Thirty-three patients diagnosed with AD were randomized to either treatment with a daily intake of 2.3 g of n-3 FAs (n  =  18) or placebo (n  =  15). CSF samples were collected at baseline and after six months of treatment, and the following biomarkers were analyzed: Aβ 38, Aβ 40, Aβ 42, t-tau, p-tau, neurofilament light (NfL), chitinase-3-like protein 1 (YKL-40), acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), soluble IL-1 receptor type II (sIL-1RII), and IL-6.

RESULTS

There were no significant differences between the groups concerning the level of the different biomarkers in the CSF at baseline. Within the treatment group, there was a small but significant increase in both YKL-40 (p = 0.04) and NfL (p = 0.03), while the other CSF biomarkers remained stable.

CONCLUSION

Supplementation with n-3 FAs had a statistically significant effect on NfL and YKL-40, resulting in an increase of both biomarkers, indicating a possible increase of inflammatory response and axonal damage. This increase in biomarkers did not correlate with MMSE score.

Evidence of upregulation of the cholinergic anti-inflammatory pathway in late-life depression

BACKGROUND

Decreased cholinergic tone associated with increased proinflammatory cytokines has been observed in several human diseases associated with low-grade inflammation. We examined if this attenuated cholinergic anti-inflammatory pathway (CAP) mechanism contributed to increased neuroinflammation observed in depression.

METHODS

We measured cerebrospinal fluid (CSF) cholinergic markers (AChE and BChE activities) in 28 individuals with longstanding late-life major depression (LLMD) and 19 controls and their relationship to central and peripheral levels of pro-inflammatory cytokines (IL-6 and IL-8). Additionally, we examined if these cholinergic indices were related to CSF markers of microglial activation and neuroinflammation (sTREM2 and complement C3).

RESULTS

Compared with controls, LLMD patients had a significant reduction in CSF BChE levels. Lower CSF BChE and AChE activities were associated with lower CSF markers of microglial and neuroinflammation (sTREM2 and C3). In addition, in LLMD patients we found an inverse relationship between peripheral marker of inflammation (plasma IL-6) and CSF BChE and AChE levels.

CONCLUSIONS

Our results suggest an upregulation of the CAP mechanism in LLMD with an elevation in peripheral markers of inflammation and concomitant reduction in markers of glial activation associated with a higher cholinergic tone. Future studies should confirm these findings in a larger sample including individuals with acute and more severe depressive episodes and across all ages.

Evaluation of cholinergic functions in patients with Japanese encephalitis and Herpes simplex encephalitis

Cognitive and memory impairment are related to cholinergic dysfunction and are important complications of viral encephalitis, In view of paucity of studies on cholinergic dysfunction in encephalitis, this study has been undertaken. We report acetyl choline esterase (AChE) and muscurinic 2 (M2) receptor levels in herpes simplex encephalitis (HSE) and Japanese encephalitis (JE) patients, and correlate these with cognitive functions and MRI findings. Patients with JE and HSE were evaluated for consciousness, neurological and MRI findings, plasma AChE and M2 receptor levels on admission and after one year. Twenty-nine patients with JE and 23 with HSE were included. Admission AChE levels in JE (48.32 ± 5.36 nmol/min/ml) and HSE (41.92 ± 5.12 nmol/min/ml) were significantly lower compared with controls (70.50 ± 8.30 nmol/min/ml). M2 receptor levels were also low in JE (4.52 ± 0.56 ng/ml) and HSE (4.35 ± 0.57 ng/ml) compared with controls (7.95 ± 0.41 ng/ml). In JE, AChE activity (r = 0.43, p = 0.02) and M2 receptor levels (r = 0.43, p = 0.02) correlated with caudate involvement, and AChE activity (r = 0.76, p = 0.03) with Mini Mental State Examination ( MMSE) score. In HSE, M2 receptor levels (r = 0.53, p = 0.03) correlated with MMSE. The levels of AChE and M2 receptors increased at one year compared to the baseline, which was greater in JE than in HSE. Both AChE and M2 receptors were reduced in JE and HSE and correlated with cognition at one year. Recovery of these biomarkers was more in JE than HSE.

Serum butyrylcholinesterase activity and phenotype associations with lipid profile in stroke patients

BACKGROUND

Butyrylcholinesterase (BuChE) catalyzes the hydrolysis of acetylcholine and other choline esters and is also involved in lipid metabolism. The purpose of this study was to investigate any association between BuChE serum phenotype and activity and lipid profile of ischemic stroke patients.

METHODS

We determined serum BuChE activities and phenotypes, and levels of total cholesterol (TC), LDL-C, HDL-C and triacylglyerol (TG) in 33 patients with acute ischemic stroke within 12 h of the onset of the attack and 29 controls.

RESULTS

The mean (+/-SD) serum BuChE activity and the BuChE of U/A phenotype in the stroke individuals were significantly lower and higher than that of the control (315 (+/-124) IU/L. vs. 384 (+/-99) IU/L, p=0.02, t=-2.4 and 21.2% vs.3.4%, p=0.026 respectively).

CONCLUSIONS

Our results showed that a negative correlation between BuChE activity with TC level, in addition the frequency of BuChE phenotypes with low activity is high in stroke patients, who have high levels of cholesterol, may have increased susceptibility to stroke.

Differential CSF butyrylcholinesterase levels in Alzheimer's disease patients with the ApoE epsilon4 allele, in relation to cognitive function and cerebral glucose metabolism

Butyrylcholinesterase (BuChE) is increased in the cerebral cortex of Alzheimer's disease (AD) patients, particularly those carrying epsilon4 allele of the apolipoprotein E gene (ApoE) and certain BuChE variants that predict increased AD risk and poor response to anticholinesterase therapy. We measured BuChE activity and protein level in CSF of eighty mild AD patients in relation to age, gender, ApoE epsilon4 genotype, cognition and cerebral glucose metabolism (CMRglc). BuChE activity was 23% higher in men than women (p<0.03) and 40-60% higher in ApoE epsilon4 negative patients than in those carrying one or two epsilon4 alleles (p<0.0004). CSF BuChE level correlated with cortical CMRglc. Patients with high to moderate CSF BuChE showed better cognitive function scores than others. We hypothesize that CSF BuChE varies inversely with BuChE in cortical amyloid plaques. Thus, low BuChE in a patient's CSF may predict extensive incorporation in neuritic plaques, increased neurotoxicity and greater central neurodegeneration.

Acetylcholinesterase assay for cerebrospinal fluid using bupivacaine to inhibit butyrylcholinesterase

BACKGROUND

Most test systems for acetylcholinesterase activity (E.C.3.1.1.7.) are using toxic inhibitors (BW284c51 and iso-OMPA) to distinguish the enzyme from butyrylcholinesterase (E.C.3.1.1.8.) which occurs simultaneously in the cerebrospinal fluid. Applying Ellman's colorimetric method, we were looking for a non-toxic inhibitor to restrain butyrylcholinesterase activity. Based on results of previous in vitro studies bupivacaine emerged to be a suitable inhibitor.

RESULTS

Pharmacokinetic investigations with purified cholinesterases have shown maximum inhibition of butyrylcholinesterase activity and minimal interference with acetylcholinesterase activity at bupivacaine final concentrations between 0.1 and 0.5 mmol/l. Based on detailed analysis of pharmacokinetic data we developed three equations representing enzyme inhibition at bupivacaine concentrations of 0.1, 0.2 and 0.5 mmol/l. These equations allow us to calculate the acetylcholinesterase activity in solutions containing both cholinesterases utilizing the extinction differences measured spectrophotometrically in samples with and without bupivacaine. The accuracy of the bupivacaine-inhibition test could be confirmed by investigations on solutions of both purified cholinesterases and on samples of human cerebrospinal fluid. If butyrylcholinesterase activity has to be assessed simultaneously an independent test using butyrylthiocholine iodide as substrate (final concentration 5 mmol/l) has to be conducted.

CONCLUSIONS

The bupivacaine-inhibition test is a reliable method using spectrophotometrical techniques to measure acetylcholinesterase activity in cerebrospinal fluid. It avoids the use of toxic inhibitors for differentiation of acetylcholinesterase from butyrylcholinesterase in fluids containing both enzymes. Our investigations suggest that bupivacaine concentrations of 0.1, 0.2 or 0.5 mmol/l can be applied with the same effect using 1 mmol/l acetylthiocholine iodide as substrate.

Butyrylcholinesterase in lumbar and ventricular cerebrospinal fluid

OBJECTIVES

This study establishes reference data for human lumbar CSF butyrylcholinesterase (E.C.3.1.1.8.) activity and investigates the enzyme activity in ventricular CSF. We comment on the relationship between CSF butyrylcholinesterase activity and other laboratory parameters.

SUBJECTS AND METHODS

We investigated 64 lumbar CSF samples obtained from a clinically healthy population and 169 ventricular CSF samples collected from 90 neurosurgical patients.

RESULTS

The reference range we recommend for lumbar CSF butyrylcholinesterase activity is 5.4 to 17.0 nmol/min x ml. The majority of ventricular butyrylcholinesterase activities in our patient subset ranged up to 5 nmol/min x ml.

CONCLUSIONS

We established the relative influence of serum and CNS components on total CSF butyrylcholinesterase activity. The CNS fraction predominates the total butyrylcholinesterase activity in normal lumbar CSF. In ventricular CSF enzyme influx from serum outweighs the CNS component.

Acetylcholinesterase in lumbar and ventricular cerebrospinal fluid

BACKGROUND

Soluble acetylcholinesterase (AChE, E.C. 3.1.1.7.) is released by neurons, glial and meningeal cells into the CSF. AChE activity in cerebrospinal fluid (CSF) is altered in various disorders of the nervous system. The objects of this study are to define a reference range for CSF AChE activity in human lumbar CSF, to prove that the enzyme activity does not depend on the blood/CSF barrier function, and to provide information about AChE in ventricular CSF. In addition, drugs used in neurosurgical care have been examined for their in vitro effects on CSF AChE activity to exclude interference with the test system.

METHODS

We tested the AChE activity in 64 lumbar CSF samples collected from a clinically healthy population and in 169 ventricular CSF samples obtained from 90 neurosurgical patients. AChE activity was assayed with our inhibitor-free test procedure.

RESULTS

The reference range determined for lumbar CSF AChE activity is 9.2-24.4 nmol/min per ml. Lumbar CSF AChE activity does not correlate with parameters characterising the status of the blood/CSF barrier. Ventricular puncture is only justified for underlying pathology making it impossible to provide reference data for ventricular CSF. Most measurements reveal ventricular enzyme activity below 4 nmol/min per ml.

CONCLUSION

The results of this study suggest the utility of lumbar CSF AChE activity as a measure of specific secretory function in enzyme releasing cells of the nervous system.

Non-classical actions of cholinesterases: role in cellular differentiation, tumorigenesis and Alzheimer's disease

The cholinesterases are members of the serine hydrolase family, which utilize a serine residue at the active site. Acetylcholinesterase (AChE) is distinguished from butyrylcholinesterase (BChE) by its greater specificity for hydrolysing acetylcholine. The function of AChE at cholinergic synapses is to terminate cholinergic neurotransmission. However, AChE is expressed in tissues that are not directly innervated by cholinergic nerves. AChE and BChE are found in several types of haematopoietic cells. Transient expression of AChE in the brain during embryogenesis suggests that AChE may function in the regulation of neurite outgrowth. Overexpression of cholinesterases has also been correlated with tumorigenesis and abnormal megakaryocytopoiesis. Acetylcholine has been shown to influence cell proliferation and neurite outgrowth through nicotinic and muscarinic receptor-mediated mechanisms and thus, that the expression of AChE and BChE at non-synaptic sites may be associated with a cholinergic function. However, structural homologies between cholinesterases and adhesion proteins indicate that cholinesterases could also function as cell-cell or cell-substrate adhesion molecules. Abnormal expression of AChE and BChE has been detected around the amyloid plaques and neurofibrillary tangles in the brains of patients with Alzheimer's disease. The function of the cholinesterases in these regions of the Alzheimer brain is unknown, but this function is probably unrelated to cholinergic neurotransmission. The presence of abnormal cholinesterase expression in the Alzheimer brain has implications for the pathogenesis of Alzheimer's disease and for therapeutic strategies using cholinesterase inhibitors.

Acetylcholinesterase induces long-term potentiation in CA1 pyramidal cells by a mechanism dependent on metabotropic glutamate receptors

Acetylcholinesterase (AChE) has additional functions within the central nervous system that are unrelated to cholinergic transmission. In the cerebellar cortex AChE has been shown to potentiate synaptic responses evoked by excitatory amino acids. Because AChE is also secreted from the terminal regions of cholinergic nerves within the hippocampus, this study investigates the actions of AChE on synaptic transmission in guinea pig hippocampal slices. Application of AChE produced a long-lasting potentiation of both the field epsp and the resulting population spike evoked by stimulation of the Schaffer/commissural-CA1 pathway. This effect was independent of any cholinergic receptor stimulation since it persisted in the presence of the cholinergic antagonists atropine and mecamylamine. Furthermore, the effect was not mimicked by butyrylcholinesterase despite its cholinolytic activity. However, the effect of AChE was dependent on metabotropic glutamate receptor stimulation since it was prevented by the metabotropic receptor antagonist (+/-)-alpha-methyl-4-carboxyphenylglycine. Perfusion with AChE therefore induces a long-lasting potentiation of hippocampal synaptic transmission which is reminiscent of the classical LTP produced by tetanic stimulation. Consequently the secreted protein could play an important role in the molecular mechanisms of learning and memory in vertebrates.