Functional variability in butyrylcholinesterase activity regulates intrathecal cytokine and astroglial biomarker profiles in patients with Alzheimer's disease

Advances in Alzheimer's disease: A multifaceted review of potential therapies and diagnostic techniques for early detection

Alzheimer's disease (AD) remains one of the most formidable neurological disorders, affecting millions globally. This review provides a holistic overview of the therapeutic strategies, both conventional and novel, aimed at mitigating the impact of AD. Initially, we delve into the conventional approach, emphasizing the role of Acetylcholinesterase (AChE) inhibition, which has been a cornerstone in AD management. As our understanding of AD evolves, several novel potential approaches emerge. We discuss the promising roles of Butyrylcholinesterase (BChE) inhibition, Tau Protein inhibitors, COX-2 inhibition, PPAR-γ agonism, and FAHH inhibition, among others. The potential of the endocannabinoids (eCB) system, cholesterol-lowering drugs, metal chelators, and MMPs inhibitors are also explored, culminating in the exploration of the pivotal role of microRNA in AD progression. Parallel to these therapeutic insights, we shed light on the novel tools and methodologies revolutionizing AD research. From the quantitative analysis of gene expression by qRTPCR to the evaluation of mitochondrial function using induced pluripotent stem cells (iPSCs), the advances in diagnostic and research tools offer renewed hope. Moreover, we explore the current landscape of clinical trials, highlighting the leading drug interventions and their respective stages of development. This comprehensive review concludes with a look into the future perspectives, capturing the potential breakthroughs and innovations on the horizon. Through a synthesis of current knowledge and emerging research, this article aims to provide a consolidated resource for clinicians, researchers, and academicians in the realm of Alzheimer's disease.

Onset of Alzheimer disease in apolipoprotein ɛ4 carriers is earlier in butyrylcholinesterase K variant carriers

BACKGROUND

The authors sought to examine the impact of the K-variant of butyrylcholinesterase (BCHE-K) carrier status on age-at-diagnosis of Alzheimer disease (AD) in APOE4 carriers.

METHODS

Patients aged 50-74 years with cerebrospinal fluid (CSF) biomarker-confirmed AD, were recruited to clinical trial (NCT03186989 since June 14, 2017). Baseline demographics, disease characteristics, and biomarkers were evaluated in 45 patients according to BCHE-K and APOE4 allelic status in this post-hoc study.

RESULTS

In APOE4 carriers (N = 33), the mean age-at-diagnosis of AD in BCHE-K carriers (n = 11) was 6.4 years earlier than in BCHE-K noncarriers (n = 22, P < .001, ANOVA). In APOE4 noncarriers (N = 12) there was no observed influence of BCHE-K. APOE4 carriers with BCHE-K also exhibited slightly higher amyloid and tau accumulations compared to BCHE-K noncarriers. A predominantly amyloid, limited tau, and limbic-amnestic phenotype was exemplified by APOE4 homozygotes with BCHE-K. In the overall population, multiple regression analyses demonstrated an association of amyloid accumulation with APOE4 carrier status (P < .029), larger total brain ventricle volume (P < .021), less synaptic injury (Ng, P < .001), and less tau pathophysiology (p-tau181, P < .005). In contrast, tau pathophysiology was associated with more neuroaxonal damage (NfL, P = .002), more synaptic injury (Ng, P < .001), and higher levels of glial activation (YKL-40, P = .01).

CONCLUSION

These findings have implications for the genetic architecture of prognosis in early AD, not the genetics of susceptibility to AD. In patients with early AD aged less than 75 years, the mean age-at-diagnosis of AD in APOE4 carriers was reduced by over 6 years in BCHE-K carriers versus noncarriers. The functional status of glia may explain many of the effects of APOE4 and BCHE-K on the early AD phenotype.

TRIAL REGISTRATION

NCT03186989 since June 14, 2017.

Presence of key cholinergic enzymes in human spermatozoa and seminal fluid†

Little is known about the non-neuronal spermic cholinergic system, which may regulate sperm motility and the acrosome reaction initiation process. We investigated the presence of the key acetylcholine (ACh)-biosynthesizing enzyme, choline acetyltransferase (ChAT), and the acetylcholine-degrading enzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and two ACh-receptors in human spermatozoa and seminal plasma. Fresh ejaculates were used for intra- and extracellular flow cytometric analysis of ChAT, AChE, BChE, and alpha-7-nicotinic and M1-muscarinic ACh-receptors in sperm. For determining the source of soluble enzymes, frozen seminal samples (n = 74) were selected on two bases: (1) from vasectomized (n = 37) and non-vasectomized (n = 37) subjects and (2) based on levels of alpha-glucosidase, fructose, or zinc to define sample subgroups with high or low fluid contribution from the epididymis and seminal vesicle, and prostate, respectively. Flow cytometric analyses revealed that ChAT was expressed intracellularly in essentially all spermatozoa. ChAT was also present in a readily membrane-detachable form at the extracellular membrane of at least 18% of the spermatozoa. These were also highly positive for intra- and extracellular BChE (>83%) and M1 (>84%) and α7 (>59%) ACh-receptors. Intriguingly, the sperm was negative for AChE. Analyses of seminal plasma revealed that spermatozoa and epididymides were major sources of soluble ChAT and BChE, whereas soluble AChE most likely originated from epididymides and seminal vesicles. Prostate had relatively minor contribution to the pool of the soluble enzymes in the seminal fluid. In conclusion, human spermatozoa exhibited a cholinergic phenotype and were one of the major sources of soluble ChAT and BChE in ejaculate. We also provide the first evidence for ChAT as an extracellularly membrane-anchored protein.

Heroin metabolism in human blood and its impact for the design of an immunotherapeutic approach against heroin effects

Immunotherapeutic interventions that block drug effects by binding drug molecules to specific antibodies in the bloodstream have shown promising effects in animal studies. For heroin, which effects are mainly mediated by the metabolites 6-acetylmorphine (6-AM; also known as 6-monoacetylmorphine or 6-MAM) and morphine, the optimal antibody specificity has been discussed. In rodents, 6-AM specific antibodies have been recommended based on the rapid metabolism of heroin to 6-AM in the bloodstream. Since the metabolic rate of heroin in blood is unsettled in humans, we examined heroin metabolism with state-of-the-art analytical methodology (UHPLC-MS/MS) in freshly drawn human whole blood incubated with a wide range of heroin concentrations (1-500 μM). The half-life of heroin was highly concentration dependent, ranging from 1.2-1.7 min for concentrations at or above 25 μM, and gradually increasing to approximately 20 min for 1 μM heroin. At concentrations that can be attained in the bloodstream shortly after an i.v. injection, approximately 70% was transformed into 6-AM within 3 min, similar to previous observations in vivo. Our results indicate that blood enzymes play a more important role for the rapid metabolism of heroin in humans than previously assumed. This points to 6-AM as an important target for an efficient immunotherapeutic approach to block heroin effects in humans.

Influence of the chronic groundwater fluoride consumption on cholinergic enzymes, ACHE and BCHE gene SNPs and pro-inflammatory cytokines: A study with Pakistani population groups

Fluoride is one of the abundant elements found in the Earth's crust and is a global environmental issue. The present work aimed to find the impact of chronic consumption of fluoride contained groundwater on human subjects. Five hundred and twelve volunteers from different areas of Pakistan were recruited. Cholinergic status, acetylcholinesterase and butyrylcholinesterase gene SNPs and pro-inflammatory cytokines were examined. Association analysis, regression and other standard statistical analyses were performed. Physical examination of the fluoride endemic areas' participants revealed the symptoms of dental and skeletal fluorosis. Cholinergic enzymes (AChE and BChE) were significantly increased among different exposure groups. ACHE gene 3'-UTR variant and BCHE K-variant showed a significant association with risk of fluorosis. Pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) were found to be increased and have a significant correlation in response to fluoride exposure and cholinergic enzymes. The study concludes that chronic consumption of high fluoride-contained water is a risk factor for developing low-grade systemic inflammation through the cholinergic pathway and the studied cholinergic gene SNPs were identified to be associated with the risk of flurosis.

Diagnosis of Alzheimer's Disease and In Situ Biological Imaging via an Activatable Near-Infrared Fluorescence Probe

Alzheimer's disease (AD) is a common neurodegenerative disease that makes the brain nervous system degenerate rapidly and is accompanied by some special cognitive and behavioral dysfunction. Recently, butyrylcholinesterase (BChE) was reported as an important enzyme, whose activity can provide predictive value for timely discovery and diagnosis of AD. Therefore, it is indispensable to design a detection tool for selective and rapid response toward BChE. In this study, we developed a novel near-infrared fluorescent probe (Chy-1) for the detection of BChE activity. An excellent sensitivity, good biocompatibility, and lower limit of detection (LOD) of 0.12 ng/mL made the probe extremely specific for BChE, which was successfully used in biological imaging. What is more, Chy-1 can not only clearly distinguish tumor from normal cells but also forms a clear boundary between the normal and cancer tissues due to the obvious difference in fluorescence intensity produced via in situ spraying. Most important of all, Chy-1 was also successfully applied to track the BChE activity in AD mouse models. Based on this research, the novel probe may be a powerful tool for clinical diagnosis and therapy of tumor and neurodegenerative diseases.

Phenotypic Displays of Cholinergic Enzymes Associate With Markers of Inflammation, Neurofibrillary Tangles, and Neurodegeneration in Pre- and Early Symptomatic Dementia Subjects

Background

Cholinergic drugs are the most commonly used drugs for the treatment of Alzheimer’s disease (AD). Therefore, a better understanding of the cholinergic system and its relation to both AD-related biomarkers and cognitive functions is of high importance.

Objectives

To evaluate the relationships of cerebrospinal fluid (CSF) cholinergic enzymes with markers of amyloidosis, neurodegeneration, neurofibrillary tangles, inflammation and performance on verbal episodic memory in a memory clinic cohort.

Methods

In this cross-sectional study, 46 cholinergic drug-free subjects (median age = 71, 54% female, median MMSE = 28) were recruited from an Icelandic memory clinic cohort targeting early stages of cognitive impairment. Enzyme activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) was measured in CSF as well as levels of amyloid-β_1–42 (Aβ₄₂), phosphorylated tau (P-tau), total-tau (T-tau), neurofilament light (NFL), YKL-40, S100 calcium-binding protein B (S100B), and glial fibrillary acidic protein (GFAP). Verbal episodic memory was assessed with the Rey Auditory Verbal Learning (RAVLT) and Story tests.

Results

No significant relationships were found between CSF Aβ₄₂ levels and AChE or BuChE activity (p > 0.05). In contrast, T-tau (r = 0.46, p = 0.001) and P-tau (r = 0.45, p = 0.002) levels correlated significantly with AChE activity. Although neurodegeneration markers T-tau and NFL did correlate with each other (r = 0.59, p < 0.001), NFL did not correlate with AChE (r = 0.25, p = 0.09) or BuChE (r = 0.27, p = 0.06). Inflammation markers S100B and YKL-40 both correlated significantly with AChE (S100B: r = 0.43, p = 0.003; YKL-40: r = 0.32, p = 0.03) and BuChE (S100B: r = 0.47, p < 0.001; YKL-40: r = 0.38, p = 0.009) activity. A weak correlation was detected between AChE activity and the composite score reflecting verbal episodic memory (r = −0.34, p = 0.02). LASSO regression analyses with a stability approach were performed for the selection of a set of measures best predicting cholinergic activity and verbal episodic memory score. S100B was the predictor with the highest model selection frequency for both AChE (68%) and BuChE (73%) activity. Age (91%) was the most reliable predictor for verbal episodic memory, with selection frequency of both cholinergic enzymes below 10%.

Conclusions

Results indicate a relationship between higher activity of the ACh-degrading cholinergic enzymes with increased neurodegeneration, neurofibrillary tangles and inflammation in the stages of pre- and early symptomatic dementia, independent of CSF Aβ₄₂ levels.

CSF and Plasma Cholinergic Markers in Patients With Cognitive Impairment

Introduction

Alzheimer’s disease (AD) is the most prevalent form of dementia with symptoms of deteriorating cognitive functions and memory loss, partially as a result of a decrease in cholinergic neurotransmission. The disease is incurable and treatment with cholinesterase inhibitors (ChEIs) is symptomatic. Choline acetyltransferase (ChAT), the enzyme that synthesizes acetylcholine (ACh), has been proven recently to be present in both cerebrospinal fluid (CSF) and plasma. As ChAT plays a role in regulating the extracellular ACh levels, it may have an impact on prognosis and cognitive performance in AD patients.

Objectives

To measure ChAT activity and its protein concentration in CSF and plasma from patients with AD, mild cognitive impairment (MCI), or Subjective cognitive impairment (SCI).

Methods

Plasma and CSF samples were obtained from 21 AD, 32 MCI, and 30 SCI patients. The activity and protein levels of ChAT and acetylcholinesterase (AChE), the enzyme catalyzing the hydrolysis of ACh, were analyzed using an integrated activity and protein concentration ELISA-like assay. A Cholinergic Index was calculated as the ratio of ChAT to AChE activities in CSF. The data were analyzed in relation to dementia biomarkers and cognitive performance of the patients.

Results

The CSF ChAT activity was significantly higher (55–67%) in MCI patients compared to AD and SCI cases. The CSF Cholinergic Index was 41 and 22% lower in AD patients than in MCI and SCI subjects, respectively. This index correlated positively with the Aβ₄₂/p-tau ratio in CSF in SCI but negatively with that in AD and MCI. The ChAT activity and protein levels in plasma exhibited significant differences with the pattern of AD>>MCI>SCI.

Conclusion

This is the first study investigating soluble levels of the key cholinergic enzyme, ChAT, in both plasma and CSF of individuals at different clinical stages of dementia. Although further validation is needed, the overall pattern of the results suggests that in the continuum of AD, the cholinergic signaling exhibits an inverse U-shape dynamic of changes in the brain that greatly differs from the changes observed in the plasma compartment.

AND-Logic Strategy for Accurate Analysis of Alzheimer's Disease via Fluorescent Probe Lighted Up by Two Specific Biomarkers

Alzheimer's disease (AD) has become a global threat to the elderly health with a short survival time after diagnosis. Due to the asymptomatic stage during the early development, patients are usually diagnosed at the middle or late stage. Therefore, an efficient tool for AD early diagnosis deserves considerable attention, which could make a significant contribution to the treatment intervention. A fluorescent probe has been widely applied for detecting and visualizing species of interest in vitro and in vivo, and the proper reaction between the probe and analytes is responsible for the fluorescence change to provide a lighting-on or ratiometric responsive pattern with satisfactory sensing behavior. In this work, we report the first attempt to build up an AND-logic probe P2 for AD accuracy diagnosis taking butyrylcholinesterase (BChE) and reactive oxygen species (ROSs) as dual targets. Upon the co-stimulation by these two factors through enzymatic hydrolysis and redox reaction, the NIR emission could be readily turned on. This AND sensing pattern avoided the false-positive response effectively, and other diseases sharing one biomarker could hardly induce a NIR fluorescence response. The sensing assay has also been confirmed to be feasible in vitro and in vivo with good sensibility and selectivity. It is worth mentioning that the probe structure has been optimized in terms of the linkage length. This study shows that probe P2 with a connecting arm of medium length (one methylene, n = 1) has superior sensing performance, promising to provide a reference for the relative structure design.

Ameliorative Role of Cerium Oxide Nanoparticles Against Fipronil Impact on Brain Function, Oxidative Stress, and Apoptotic Cascades in Albino Rats

Fipronil (FIP) is an N-phenylpyrazole insecticide that is used extensively in public health and agriculture against a wide range of pests. Exposure to FIP is linked to negative health outcomes in humans and animals including promoting neuronal cell injury, which results in apoptosis through the production of reactive oxygen species (ROS). Therefore, the purpose of the current study was to investigate the neuroprotective effects of cerium oxide nanoparticles (CeNPs) on neuronal dysfunction induced by FIP in albino rats. Male rats were randomly classified into four groups: control, FIP (5 mg/kg bwt), CeNPs (35 mg/kg bwt), and FIP + CeNPs (5 (FIP) + 35 (CeNPs) mg/kg bwt), which were treated orally once daily for 28 consecutive days. Brain antioxidant parameters, histopathology, and mRNA expression of genes related to brain function were evaluated. The results revealed oxidative damage to brain tissues in FIP-treated rats indicated by the elevated levels of malondialdehyde (MDA) and nitric oxide (NO) levels and reduced activities of antioxidant enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GPx). On the other hand, the FIP’s group that was treated with CeNPs showed decrease in MDA and NO levels and increase in SOD and GPx enzymes activity. Besides, FIP-treated rats showed decreased butyrylcholinesterase (BuChE) activity in comparison to the FIP + CeNPs group. Moreover, FIP caused up-regulation of the expression of neuron-specific enolase (NSE), caspase-3, and glial fibrillary acidic protein (GFAP) but down-regulation of B-cell lymphoma-2 (BCL-2) expression. But the FIP + CeNPs group significantly down-regulated the GFAP, NSE, and caspase-3 and up-regulated the gene expression of BCL-2. Additionally, the FIP-treated group of rats had clear degenerative lesions in brain tissue that was reversed to nearly normal cerebral architecture by the FIP + CeNPs treatment. Immunohistochemical examination of brain tissues of rats-treated with FIP showed abundant ionized calcium-binding adaptor molecule 1 (Iba-1) microglia and caspase-3 and apoptotic cells with nearly negative calbindin and synaptophysin reaction, which were countered by FIP + CeNPs treatment that revealed a critical decrease in caspase-3, Iba-1 reaction with a strong calbindin positive reaction in most of the Purkinje cells and strong synaptophysin reaction in the cerebrum and cerebellum tissues. Based on reported results herein, CeNPs treatment might counteract the neurotoxic effect of FIP pesticide via an antioxidant-mediated mechanism.

Sustainable Drug Discovery of Multi-Target-Directed Ligands for Alzheimer's Disease

The multifactorial nature of Alzheimer's disease (AD) is a reason for the lack of effective drugs as well as a basis for the development of "multi-target-directed ligands" (MTDLs). As cases increase in developing countries, there is a need of new drugs that are not only effective but also accessible. With this motivation, we report the first sustainable MTDLs, derived from cashew nutshell liquid (CNSL), an inexpensive food waste with anti-inflammatory properties. We applied a framework combination of functionalized CNSL components and well-established acetylcholinesterase (AChE)/butyrylcholinesterase (BChE) tacrine templates. MTDLs were selected based on hepatic, neuronal, and microglial cell toxicity. Enzymatic studies disclosed potent and selective AChE/BChE inhibitors (5, 6, and 12), with subnanomolar activities. The X-ray crystal structure of 5 complexed with BChE allowed rationalizing the observed activity (0.0352 nM). Investigation in BV-2 microglial cells revealed antineuroinflammatory and neuroprotective activities for 5 and 6 (already at 0.01 μM), confirming the design rationale.

Fluorescent Determination of Butyrylcholinesterase Activity and Its Application in Biological Imaging and Pesticide Residue Detection

Butyrylcholinesterase (BChE) is an essential human cholinesterase relevant to liver conditions and neurodegenerative diseases, which makes it a pivotal biomarker of health. It therefore remains challenging and highly desired to elaborate efficient chemical tools for BChE with simple operations and satisfactory working performance. In this work, a background-free detection strategy was built by virtue of the judicious coupling of a specific BChE-enzymatic reaction and in situ cyclization. High sensitivity with a low limit of detection (LOD) of 0.075 μg/mL could be readily achieved from the blank background and the as-produced emissive indicators, and the specific reaction site contributed to the high selectivity over other bio-species even acetylcholinesterase (AChE). In addition to the multifaceted spectral experiments to verify the sensing mechanism, this work assumed comprehensive studies on the application. The bio-investigation ranged from cells to an organism, declaring a noteworthy prospect in disease diagnosis, especially for Alzheimer's disease (AD), a common neurodegenerative disease with over-expressed BChE. Moreover, its excellent work for inhibition efficacy elucidation was also proved with the accuracy IC₅₀ of tacrine for BChE (8.6 nM), giving rise to an expanded application for trace pesticide determination.

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.

The Role of Butyrylcholinesterase and Iron in the Regulation of Cholinergic Network and Cognitive Dysfunction in Alzheimer's Disease Pathogenesis

Alzheimer’s disease (AD), the most common form of dementia in elderly individuals, is marked by progressive neuron loss. Despite more than 100 years of research on AD, there is still no treatment to cure or prevent the disease. High levels of amyloid-β (Aβ) plaques and neurofibrillary tangles (NFTs) in the brain are neuropathological hallmarks of AD. However, based on postmortem analyses, up to 44% of individuals have been shown to have high Aβ deposits with no clinical signs, due to having a “cognitive reserve”. The biochemical mechanism explaining the prevention of cognitive impairment in the presence of Aβ plaques is still unknown. It seems that in addition to protein aggregation, neuroinflammatory changes associated with aging are present in AD brains that are correlated with a higher level of brain iron and oxidative stress. It has been shown that iron accumulates around amyloid plaques in AD mouse models and postmortem brain tissues of AD patients. Iron is required for essential brain functions, including oxidative metabolism, myelination, and neurotransmitter synthesis. However, an imbalance in brain iron homeostasis caused by aging underlies many neurodegenerative diseases. It has been proposed that high iron levels trigger an avalanche of events that push the progress of the disease, accelerating cognitive decline. Patients with increased amyloid plaques and iron are highly likely to develop dementia. Our observations indicate that the butyrylcholinesterase (BChE) level seems to be iron-dependent, and reports show that BChE produced by reactive astrocytes can make cognitive functions worse by accelerating the decay of acetylcholine in aging brains. Why, even when there is a genetic risk, do symptoms of the disease appear after many years? Here, we discuss the relationship between genetic factors, age-dependent iron tissue accumulation, and inflammation, focusing on AD.

Association of glial and neuronal degeneration markers with Alzheimer's disease cerebrospinal fluid profile and cognitive functions

BACKGROUND

Neuroinflammation has gained increasing attention as a potential contributing factor in the onset and progression of Alzheimer's disease (AD). The objective of this study was to examine the association of selected cerebrospinal fluid (CSF) inflammatory and neuronal degeneration markers with signature CSF AD profile and cognitive functions among subjects at the symptomatic pre- and early dementia stages.

METHODS

In this cross-sectional study, 52 subjects were selected from an Icelandic memory clinic cohort. Subjects were classified as having AD (n = 28, age = 70, 39% female, Mini-Mental State Examination [MMSE] = 27) or non-AD (n = 24, age = 67, 33% female, MMSE = 28) profile based on the ratio between CSF total-tau (T-tau) and amyloid-β_1-42 (Aβ₄₂) values (cut-off point chosen as 0.52). Novel CSF biomarkers included neurofilament light (NFL), YKL-40, S100 calcium-binding protein B (S100B) and glial fibrillary acidic protein (GFAP), measured with enzyme-linked immunosorbent assays (ELISAs). Subjects underwent neuropsychological assessment for evaluation of different cognitive domains, including verbal episodic memory, non-verbal episodic memory, language, processing speed, and executive functions.

RESULTS

Accuracy coefficient for distinguishing between the two CSF profiles was calculated for each CSF marker and test. Novel CSF markers performed poorly (area under curve [AUC] coefficients ranging from 0.61 to 0.64) compared to tests reflecting verbal episodic memory, which all performed fair (AUC > 70). LASSO regression with a stability approach was applied for the selection of CSF markers and demographic variables predicting performance on each cognitive domain, both among all subjects and only those with a CSF AD profile. Relationships between CSF markers and cognitive domains, where the CSF marker reached stability selection criteria of > 75%, were visualized with scatter plots. Before calculations of corresponding Pearson's correlations coefficients, composite scores for cognitive domains were adjusted for age and education. GFAP correlated with executive functions (r = - 0.37, p = 0.01) overall, while GFAP correlated with processing speed (r = - 0.68, p < 0.001) and NFL with verbal episodic memory (r = - 0.43, p = 0.02) among subjects with a CSF AD profile.

CONCLUSIONS

The novel CSF markers NFL and GFAP show potential as markers for cognitive decline among individuals with core AD pathology at the symptomatic pre- and early stages of dementia.

Cerebrospinal fluid markers analysis in the differential diagnosis of dementia with Lewy bodies and Parkinson's disease dementia

Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) share a couple of clinical similarities that is often a source of diagnostic pitfalls. We evaluated the discriminatory potential of brain-derived CSF markers [tau, p-tau (181P), Aβ_1-42, NSE and S100B] across the spectrum of Lewy body disorders and assessed whether particular markers are associated with cognitive status in investigated patients. The tau CSF level, amyloid β_1-42 and p-tau/tau ratio were helpful in the distinction between DLB and PDD (p = 0.04, p = 0.002 and p = 0.02, respectively) as well as from PD patients (p < 0.001, p = 0.001 and p = 0.002, respectively). Furthermore, the p-tau/tau ratio enabled the differentiation of DLB with mild dementia from PDD patients (p = 0.02). The CSF tau and p-tau levels in DLB and CSF tau and p-tau/tau ratio in PDD patients reflected the severity of dementia. Rapid disease course was associated with the decrease of Aβ_1-42 in DLB but not in PDD. Elevation of S100B in DLB (p < 0.0001) as well as in PDD patients (p = 0.002) in comparison to controls was estimated. Hence, with the appropriate clinical context; the CSF marker profile could be helpful in distinguishing DLB from PDD patients even in early stages of dementia.

Immunohistochemical analysis for acetylcholinesterase and choline acetyltransferase in mouse cerebral cortex after traumatic brain injury

The regulation of glial cells, especially astrocytes and microglia, is important to prevent the exacerbation of a brain injury because over-reactive glial cells promote neuronal death. Acetylcholine (ACh), a neurotransmitter synthesized and hydrolyzed by choline acetyltransferase (ChAT) and acetylcholinesterase (AChE), respectively, in the central nervous system, has the potential to regulate glial cells’ states, i.e., non-reactive and reactive states. However, the expression levels of these ACh-related enzymes in areas containing reactive glial cells are unclear. Herein we immunohistochemically investigated the distributions of AChE and ChAT with reactive glial cells in the cryo-injured brain of mice as a traumatic brain injury model. Immunohistochemistry revealed AChE- and ChAT-immunopositive signals in injured areas at 7 days post-injury. The signals were observed in and around glial fibrillary acidic protein (GFAP)- or CD68-immunopositive cells, and the numbers of cells doubly positive for GFAP/AChE, GFAP/ChAT, CD68/AChE, and CD68/ChAT were significantly increased in injured areas compared to sham-operated areas. Enzyme histochemistry for AChE showed intensely positive signals in injured areas. These results suggest that reactive astrocytes and microglia express and secrete AChE and ChAT in brain-injury areas. These glial cells may adjust the ACh concentration around themselves through the regulation of the expression of ACh-related enzymes in order to control their reactive states.

Enhanced Contextual Fear Memory and Elevated Astroglial Glutamate Synthase Activity in Hippocampal CA1 BChE shRNA Knockdown Mice

Butyrylcholinesterase (BChE) efficiently hydrolyzes acetylcholine (ACh) at high concentrations when acetylcholinesterase (AChE) is substrate-inhibited. Recent studies have shown that BChE also has a function that is independent of ACh, but it has not been fully explored. Low BChE expression is accompanied with higher stress-induced aggression and ghrelin levels in stress models, and BChE knockout mice exhibit cognitive and memory impairments. However, the role of BChE in posttraumatic stress disorder (PTSD) remains unclear. In the present study, we investigated the role of BChE in contextual fear memory and its regulatory effect on the expression of factors related to the glutamate (Glu)-glutamine (Gln) cycle via knockdown studies. We used AAVs and lentiviruses to knockdown BChE expression in the mouse hippocampal CA1 region and C8D1A astrocytes. Our behavioral data from those mice injected with AAV-shBChE in the hippocampal CA1 region showed strengthened fear memory and increased dendritic spine density. Elevated Glu levels and glutamine synthetase (GS) enzyme activity were detected in contextual fear conditioned-BChE knockdown animals and astrocytes. We observed that an AAV-shBChE induced lowering of BChE expression in the hippocampus CA1 region enhanced contextual fear memory expression and promoted the astrocytic Glu-Gln cycle but did not elevate ACh-hydrolyzing activity. This study provides new insight into the regulatory role of BChE in cognition and suggests potential target for stress-related psychiatric disorder such as PTSD where patients experience fear after exposure to severe life-threatening traumatic events.

Homomeric and Heteromeric Aβ Species Exist in Human Brain and CSF Regardless of Alzheimer's Disease Status and Risk Genotype

Background: A fundamental question in Alzheimer’s disease (AD) is whether amyloid-β (Aβ) peptides and their deposition in the brain signify a direct pathological role or they are mere outcome of the disease pathophysiological events affecting neuronal function. It is therefore important to decipher their physiological role in the brain. So far, the overwhelming focus has been on the potential toxicity of Aβ, often studied outside the crucial AD characteristics, i.e.: (i) the slow, decades-long disease progression that precedes clinical symptoms; (ii) the link to apolipoprotein-E ε4 allele as major risk factor; (iii) the selective early degeneration of cholinergic neurons. Previous studies, in vitro and cerebrospinal fluid (CSF) only, indicated one possible native function of Aβ peptides is the allosteric modulation of acetylcholine homeostasis, via molecular interactions between Aβ, apolipoprotein-E, and the acetylcholine-degrading enzymes, cholinesterases, resulting in the formation of acetylcholine-hydrolyzing complexes (BAβACs).

Methods: Here, by combining sucrose-density gradient fractionation of post-mortem brains and in-house developed sensitive ELISA assays on the obtained fractions, we investigated the presence, levels and molecular interactions between Aβ, apolipoprotein-E and cholinesterases for the first time in brain tissues. We examined three distinct brain regions of Alzheimer and non-demented subjects, plus a large number of Alzheimer CSF samples.

Results: We report that both monomeric and oligomeric (homomeric and heteromeric) forms of Aβ peptides are present in the brain of Alzheimer and non-demented individuals. Heteromeric Aβ was found in stable complexes with apolipoprotein-E and/or cholinesterases, irrespective of APOE genotype or disease status, arguing in favor of a physiological dynamic formation and function for these complexes in the brain. The patterns and molecular sizes of the detected soluble Aβ forms were closely matched between CSF and brain samples. This evinces that the detected Aβ-apolipoprotein-E complexes and BAβACs in CSF most likely originate from the interstitial fluids of the brain.

Conclusions: In conclusion, both light homomeric Aβ oligomers and heteromeric Aβ-ApoE and BAβACs are present and readily detectable in the brain, regardless of disease status and APOE4 genotype. Deeper knowledge of the physiological function of Aβ is crucial for better understanding the early pathological events that decades later lead to manifestation of AD.

Discovery of Butyrylcholinesterase-Activated Near-Infrared Fluorogenic Probe for Live-Cell and In Vivo Imaging

Butyrylcholinesterase (BChE) is widely distributed in various tissues and highly implicated in several important human diseases, especially Alzheimer's disease (AD). However, the role of BChE in AD is still controversial, which may be partially attributed to the lack of a direct tool for real-time and noninvasive monitoring of BChE in in vivo. Here, we report three rationally designed near-infrared fluorogenic probes that possess excellent discrimination for butyrylcholinesterase (BChE) over the related enzyme acetylcholinesterase (AChE). The refined probe, BChE-NIRFP, not only functions as an exquisite substrate for BChE in in vitro assays but also represents a superb "signal-on" imaging tool to real-time track BChE levels in human cells, zebrafish, and a mouse model of AD. A further application of BChE-NIRFP to identify the cellular mechanism reveals that Aβ fibrils and insulin resistance may be important contributors to the abnormally elevated BChE levels observed during AD progression. Based on the results from the present study, this new probe is a valuable tool for basic and clinical research designed to obtain a complete understanding of the physiological roles of BChE in diverse human diseases, particularly AD.

Increased Active OMI/HTRA2 Serine Protease Displays a Positive Correlation with Cholinergic Alterations in the Alzheimer's Disease Brain

OMI/HTRA2 (high-temperature requirement serine protease A2) is a mitochondrial serine protease involved in several cellular processes, including autophagy, chaperone activity, and apoptosis. Few studies on the role of OMI/HTRA2 in Alzheimer's disease (AD) are available, but none on its relationship with the cholinergic system and neurotrophic factors as well as other AD-related proteins. In this study, immunohistochemical analyses revealed that AD patients had a higher cytosolic distribution of OMI/HTRA2 protein compared to controls. Quantitative analyses on brain extracts indicated a significant increase in the active form of OMI/HTRA2 in the AD brain. Activated OMI/HTRA2 protein positively correlated with stress-associated read-through acetylcholinesterase activity. In addition, α7 nicotinic acetylcholine receptor gene expression, a receptor also known to be localized on the outer membrane of mitochondria, showed a strong correlation with OMI/HTRA2 gene expression in three different brain regions. Interestingly, the activated OMI/HTRA2 levels also correlated with the activity of the acetylcholine-biosynthesizing enzyme, choline acetyltransferase (ChAT); with levels of the neurotrophic factors, NGF and BDNF; with levels of the soluble fragments of amyloid precursor protein (APP); and with gene expression of the microtubule-associated protein tau in the examined brain regions. Overall, the results demonstrate increased levels of the mitochondrial serine protease OMI/HTRA2, and a coherent pattern of association between the activated form of OMI/HTRA2 and several key proteins involved in AD pathology. In this paper, we propose a new hypothetical model to highlight the importance and needs of further investigation on the role of OMI/HTRA2 in the mitochondrial function and AD.

Molecular Imaging of the Cholinergic System in Parkinson's Disease

One of the first identified neurotransmitters in the brain, acetylcholine, is an important modulator that drives changes in neuronal and glial activity. For more than two decades, the main focus of molecular imaging of the cholinergic system in Parkinson's disease (PD) has been on cognitive changes. Imaging studies have confirmed that degeneration of the cholinergic system is a major determinant of dementia in PD. Within the last decade, the focus is expanding to studying cholinergic correlates of mobility impairments, dyskinesias, olfaction, sleep, visual hallucinations and risk taking behavior in this disorder. These studies increasingly recognize that the regional topography of cholinergic brain areas associates with specific functions. In parallel with this trend, more recent molecular cholinergic imaging approaches are investigating cholinergic modulatory functions and contributions to large-scale brain network functions. A novel area of research is imaging cholinergic innervation functions of peripheral autonomic organs that may have the potential of future prodromal diagnosis of PD. Finally, emerging evidence of hypercholinergic activity in prodromal and symptomatic leucine-rich repeat kinase 2 PD may reflect neuronal cholinergic compensation versus a response to neuro-inflammation. Molecular imaging of the cholinergic system has led to many new insights in the etiology of dopamine non-responsive symptoms of PD (more "malignant" hypocholinergic disease phenotype) and is poised to guide and evaluate future cholinergic drug development in this disorder.

Cholinergic Modification of Neurogenesis and Gliosis Improves the Memory of AβPPswe/PSEN1dE9 Alzheimer's Disease Model Mice Fed a High-Fat Diet

We previously reported that neuroinflammation contributes to the amnesia of AβPPswe/PSEN1dE9 Alzheimer's disease model mice fed a high-fat diet to induce type-2 diabetes (T2DM-AD mice), but the underlying mechanism for the memory decline remained unclear. Recent studies have suggested that cholinergic modulation is involved in neuroinflammatory cellular reactions including neurogenesis and gliosis, and in memory improvement. In this study, we administered a broad-spectrum cholinesterase inhibitor, rivastigmine (2 mg/kg/day, s.c.), into T2DM-AD mice for 6 weeks, and evaluated their memory performance, neurogenesis, and neuroinflammatory reactions. By two hippocampal-dependent memory tests, the Morris water maze and contextual fear conditioning, rivastigmine improved the memory deterioration of the T2DM-AD mice (n = 8, p < 0.01). The number of newborn neurons in the hippocampal dentate gyrus was 1138±324 (Ave±SEM) in wild-type littermates, 2573±442 in T2DM-AD-Vehicle, and 2165±300 in T2DM-AD-Rivastigmine mice, indicating that neurogenesis was accelerated in the two T2DM-AD groups (n = 5, p < 0.05). The dendritic maturation of new neurons in T2DM-AD-Vehicle mice was severely abrogated, and rivastigmine treatment reversed this retarded maturation. In addition, the hippocampus of T2DM-AD-Vehicle mice showed increased proinflammatory cytokines IL-1β and TNF-α and gliosis, and rivastigmine treatment blocked these inflammatory reactions. Rivastigmine did not change the insulin abnormality or amyloid pathology in these mice. Thus, cholinergic modulation by rivastigmine treatment led to enhanced neurogenesis and the suppression of gliosis, which together ameliorated the memory decline in T2DM-AD model mice.

Butyrylcholinesterase and Acetylcholinesterase polymorphisms in Multiple Sclerosis patients: implication in peripheral inflammation

Multiple Sclerosis (MS) is an autoimmune disease, having not fully understood aetiology, and both genetic and environmental factors contribute to the pathogenesis of the disease. The cholinergic system has been indicated as a mediator of neuro-immune interactions, as well as an internal regulator of immune responses. The aim of the present research was to assess the associations between BChE and AChE genetic variations and serum cholinergic and inflammatory profiles in 102 Relapsing Remitting-MS patients and 117 healthy controls. An increased frequency of the BChE K-allele in MS patients as compared to controls was found. In addition, data showed that patients had higher BChE enzymatic activity, which is increased by the presence of the polymorphic allele and reduced amounts of circulating ACh. AChE polymorphism was significantly associated to reduced activity in both patients and controls. We propose that serum BChE and AChE activity may be used as a secondary markers to assess the role of non-neuronal cholinergic system in regulating peripheral inflammation via ACh regulation. This pilot study shed light on the role of the non-neuronal cholinergic system in immune cells to better understand MS pathogenesis. The cross-talk between the periphery and the CNS could have a new undescribed crucial role for MS, regarded as a systemic disease.

Association of Butyrylcholinesterase-K Allele and Apolipoprotein E ɛ4 Allele with Cognitive Decline in Dementia with Lewy Bodies and Alzheimer's Disease

BACKGROUND

A common polymorphism of the butyrylcholinesterase gene, the K-variant (BCHE-K) is associated with reduced butyrylcholinesterase (BuChE) activity. Insufficient studies exist regarding the frequency and role of BCHE-K in dementias.

OBJECTIVE

To determine the association of BCHE-K and APOEɛ4 with diagnosis and rate of cognitive decline in dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) patients.

METHODS

Genomic DNA from 368 subjects (108 AD, 174 DLB, and 86 controls) from two routine clinical cohort studies in Norway; DemVest and TrønderBrain, were genotyped for BCHE-K and APOEɛ4. The mild dementia DemVest subjects received annual Mini-Mental State Examination assessments for five years.

RESULTS

BCHE-K frequency was lower in DLB (33.9% ; p <  0.01) than in control subjects (51.2%), and was numerically lower in AD as well (38.9% ; p = 0.11). More rapid cognitive decline was associated with the APOEɛ4 genotype, but not with the BCHE-K genotype. In an exploratory analysis of patients who completed all five follow-up visits, there was greater cognitive decline in BCHE-K carriers in the presence of the APOEɛ4 allele than in the absence of these polymorphisms.

CONCLUSION

BCHE-K is associated with a reduced risk for AD and DLB whereas APOEɛ4 is associated with more rapid cognitive decline. The greater cognitive decline in individuals with both APOEɛ4 and BCHE-K alleles require prospective confirmation in well-controlled trials.

Immunomodulatory effects of nicotine on interleukin 1β activated human astrocytes and the role of cyclooxygenase 2 in the underlying mechanism

Background

The cholinergic anti-inflammatory pathway (CAP) primarily functions through acetylcholine (ACh)-alpha7 nicotinic acetylcholine receptor (α7nAChR) interaction on macrophages to control peripheral inflammation. Interestingly, ACh can also bind α7nAChRs on microglia resulting in neuroprotective effects. However, ACh effects on astrocytes remain elusive. Here, we investigated the effects of nicotine, an ACh receptor agonist, on the cytokine and cholinesterase production of immunocompetent human astrocytes stimulated with interleukin 1β (IL-1β) in vitro. In addition, the potential involvement of prostaglandins as mediators of nicotine was studied using cyclooxygenase 2 (COX-2) inhibition.

Methods

Cultured human fetal astrocytes were stimulated with human recombinant IL-1β and treated simultaneously with nicotine at different concentrations (1, 10, and 100 μM). Cell supernatants were collected for cytokine and cholinesterase profiling using ELISA and MesoScale multiplex assay. α7nAChR expression on activated human astrocytes was studied using immunofluorescence. For the COX-2 inhibition studies, enzyme activity was inhibited using NS-398. One-way ANOVA was used to perform statistical analyses.

Results

Nicotine treatment dose dependently limits the production of critical proinflammatory cytokines such as IL-6 (60.5 ± 3.3, %inhibition), IL-1β (42.4 ± 1.7, %inhibition), and TNF-α (68.9 ± 7.7, %inhibition) by activated human astrocytes. Interestingly, it also inhibits IL-8 chemokine (31.4 ± 8.5, %inhibition), IL-13 (34.243 ± 4.9, %inhibition), and butyrylcholinesterase (20.8 ± 2.8, %inhibition) production at 100 μM. Expression of α7nAChR was detected on the activated human astrocytes. Importantly, nicotine’s inhibitory effect on IL-6 production was reversed with the specific COX-2 inhibitor NS-398.

Conclusions

Activation of the cholinergic system through α7nAChR agonists has been known to suppress inflammation both in the CNS and periphery. In the CNS, earlier experimental data shows that cholinergic activation through nicotine inhibits microglial activation and proinflammatory cytokine release. Here, we report similar anti-inflammatory effects of cholinergic activation on human astrocytes, at least partly mediated through the COX-2 pathway. These results confirm the potential for cholinergic neuroprotection, which is looked upon as a promising therapy for neuroinflammation as well as neurodegenerative diseases and stroke. Our data implicates an important role for the prostaglandin system in cholinergic regulatory effects.

Pharmacological Effects of a Monoclonal Antibody against 6-Monoacetylmorphine upon Heroin-Induced Locomotor Activity and Pharmacokinetics in Mice

Immunotherapy can provide a supplemental treatment strategy against heroin use on the principle of sequestering the active drug in the bloodstream, thereby reducing its distribution to the brain. Previous studies have shown that heroin's first metabolite, 6-monoacetylmorphine (6-MAM), is the main mediator of acute heroin effects. The objective of the present study was to characterize the pharmacological potential of a monoclonal antibody against 6-MAM (anti-6-MAM mAb) to counteract the heroin response. The individual contributions from heroin and 6-MAM to heroin effects were also examined by pretreating mice with anti-6-MAM mAb (10-100 mg/kg) prior to either heroin or 6-MAM injection (1.25-2.5 μmol/kg). The opioid-induced behavioral response was assessed in a locomotor activity test, followed by opioid and antibody quantification in blood and brain tissue. Pretreatment with mAb caused a profound reduction of heroin- and 6-MAM-induced behavior, accompanied by correspondingly decreased levels of 6-MAM in brain tissue. mAb pretreatment was more efficient against 6-MAM injection than against heroin, leading to an almost complete blockade of 6-MAM-induced effects. mAb pretreatment was unable to block the immediate (5-minute) transport of active metabolites across the blood-brain barrier after heroin injection, indicating that heroin itself appears to enhance the immediate delivery of 6-MAM to the brain. The current study provides additional evidence that 6-MAM sequestration is crucial for counteracting the acute heroin response, and demonstrates the pharmacological potential of immunotherapy against heroin use.

Cholinesterases as markers of the inflammatory process associated oxidative stress in cattle infected by Babesia bigemina

The objective of this study was to assess the influence of an asymptomatic experimental infection by Babesia bigemina on cholinesterase's as markers of the inflammatory process and biomarkers of oxidative imbalance. For this purpose, eight naive animals were used, as follows: four as controls or uninfected; and four infected with an attenuated strain of B. bigemina. Blood samples were collected on days 0, 7 and 11 post-inoculation (PI). Parasitemia was determined by blood smear evaluation, showing that the infection by B. bigemina resulted in mean 0.725 and 0.025% on day 7 and 11 PI, respectively, as well as mild anemia. The activities of acetylcholinesterase, butyrylcholinesterase and catalase were lower, while levels of thiobarbituric acid reactive substances and superoxide dismutase activity were higher in infected animals, when compared with the control group. This attenuated strain of B. bigemina induced an oxidative stress condition, as well as it reduces the cholinesterasés activity in infected and asymptomatic cattle. Therefore, this decrease of cholinesterase in infection by B. bigemina purpose is to inhibit inflammation, for thereby increasing acetylcholine levels, potent anti-inflammatory molecules.

CSF complement 3 and factor H are staging biomarkers in Alzheimer's disease

Introduction

CSF levels of established Alzheimer’s disease (AD) biomarkers remain stable despite disease progression, and non-amyloid non-tau biomarkers have the potential of informing disease stage and progression. We previously identified complement 3 (C3) to be decreased in AD dementia, but this change was not found by others in earlier AD stages. We hypothesized that levels of C3 and associated factor H (FH) can potentially distinguish between mild cognitive impairment (MCI) and dementia stages of AD, but we also found their levels to be influenced by age and disease status.

Results

We developed a biochemical/bioinformatics pipeline to optimize the handling of complex interactions between variables in validating biochemical markers of disease. We used data from the Alzheimer’s Disease Neuro-imaging Initiative (ADNI, n = 230) to build parallel machine learning models, and objectively tested the models in a test cohort (n = 73) of MCI and mild AD patients independently recruited from Emory University. Whereas models incorporating age, gender, APOE ε4 status, and CSF amyloid and tau levels failed to reliably distinguish between MCI and mild AD in ADNI, introduction of CSF C3 and FH levels reproducibly improved the distinction between the two AD stages in ADNI (p < 0.05) and the Emory cohort (p = 0.014). Within each AD stage, the final model also distinguished between fast vs. slower decliners (p < 0.001 for MCI, p = 0.007 for mild AD), with lower C3 and FH levels associated with more advanced disease and faster progression.

Conclusions

We propose that CSF C3 and FH alterations may reflect stage-associated biomarker changes in AD, and can complement clinician diagnosis in diagnosing and staging AD using the publically available ADNI database as reference.

Electronic supplementary material

The online version of this article (doi:10.1186/s40478-016-0277-8) contains supplementary material, which is available to authorized users.

Astrogliosis: An integral player in the pathogenesis of Alzheimer's disease

Alzheimer's disease is the main cause of dementia in the elderly and begins with a subtle decline in episodic memory followed by a more general decline in overall cognitive abilities. Though the exact trigger for this cascade of events remains unknown the presence of the misfolded amyloid-beta protein triggers reactive gliosis, a prominent neuropathological feature in the brains of Alzheimer's patients. The cytoskeletal and morphological changes of astrogliosis are its evident features, while changes in oxidative stress defense, cholesterol metabolism, and gene transcription programs are less manifest. However, these latter molecular changes may underlie a disruption in homeostatic regulation that keeps the brain environment balanced. Astrocytes in Alzheimer's disease show changes in glutamate and GABA signaling and recycling, potassium buffering, and in cholinergic, purinergic, and calcium signaling. Ultimately the dysregulation of homeostasis maintained by astrocytes can have grave consequences for the stability of microcircuits within key brain regions. Specifically, altered inhibition influenced by astrocytes can lead to local circuit imbalance with farther reaching consequences for the functioning of larger neuronal networks. Healthy astrocytes have a role in maintaining and modulating normal neuronal communication, synaptic physiology and energy metabolism, astrogliosis interferes with these functions. This review considers the molecular and functional changes occurring during astrogliosis in Alzheimer's disease, and proposes that astrocytes are key players in the development of dementia.

Dysregulated cholinergic network as a novel biomarker of poor prognostic in patients with head and neck squamous cell carcinoma

BACKGROUND

In airways, a proliferative effect is played directly by cholinergic agonists through nicotinic and muscarinic receptors activation. How tumors respond to aberrantly activated cholinergic signalling is a key question in smoking-related cancer. This research was addressed to explore a possible link of cholinergic signalling changes with cancer biology.

METHODS

Fifty-seven paired pieces of head and neck squamous cell carcinoma (HNSCC) and adjacent non-cancerous tissue (ANCT) were compared for their mRNA levels for ACh-related proteins and ACh-hydrolyzing activity.

RESULTS

The measurement in ANCT of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities (5.416 ± 0.501 mU/mg protein and 6.350 ± 0.599 mU/mg protein, respectively) demonstrated that upper respiratory tract is capable of controlling the availability of ACh. In HNSCC, AChE and BChE activities dropped to 3.584 ± 0.599 mU/mg protein (p = 0.002) and 3.965 ± 0.423 mU/mg protein (p < 0.001). Moreover, tumours with low AChE activity and high BChE activity were associated with shorter patient overall survival. ANCT and HNSCC differed in mRNA levels for AChE-T, α3, α5, α9 and β2 for nAChR subunits. Tobacco exposure had a great impact on the expression of both AChE-H and AChE-T mRNAs. Unaffected and cancerous pieces contained principal AChE dimers and BChE tetramers. The lack of nerve-born PRiMA-linked AChE agreed with pathological findings on nerve terminal remodelling and loss in HNSCC.

CONCLUSIONS

Our results suggest that the low AChE activity in HNSCC can be used to predict survival in patients with head and neck cancer. So, the ChE activity level can be used as a reliable prognostic marker.

Complement component C3 and butyrylcholinesterase activity are associated with neurodegeneration and clinical disability in multiple sclerosis

Dysregulation of the complement system is evident in many CNS diseases but mechanisms regulating complement activation in the CNS remain unclear. In a recent large rat genome-wide expression profiling and linkage analysis we found co-regulation of complement C3 immediately downstream of butyrylcholinesterase (BuChE), an enzyme hydrolyzing acetylcholine (ACh), a classical neurotransmitter with immunoregulatory effects. We here determined levels of neurofilament-light (NFL), a marker for ongoing nerve injury, C3 and activity of the two main ACh hydrolyzing enzymes, acetylcholinesterase (AChE) and BuChE, in cerebrospinal fluid (CSF) from patients with MS (n = 48) and non-inflammatory controls (n = 18). C3 levels were elevated in MS patients compared to controls and correlated both to disability and NFL. C3 levels were not induced by relapses, but were increased in patients with ≥9 cerebral lesions on magnetic resonance imaging and in patients with progressive disease. BuChE activity did not differ at the group level, but was correlated to both C3 and NFL levels in individual samples. In conclusion, we show that CSF C3 correlates both to a marker for ongoing nerve injury and degree of disease disability. Moreover, our results also suggest a potential link between intrathecal cholinergic activity and complement activation. These results motivate further efforts directed at elucidating the regulation and effector functions of the complement system in MS, and its relation to cholinergic tone.

Changes in CSF cholinergic biomarkers in response to cell therapy with NGF in patients with Alzheimer's disease

INTRODUCTION

The extensive loss of central cholinergic functions in Alzheimer's disease (AD) brain is linked to impaired nerve growth factor (NGF) signaling. The cardinal cholinergic biomarker is the acetylcholine synthesizing enzyme, choline acetyltransferase (ChAT), which has recently been found in cerebrospinal fluid (CSF). The purpose of this study was to see if EC-NGF therapy will alter CSF levels of cholinergic biomarkers, ChAT, and acetylcholinesterase.

METHOD

Encapsulated cell implants releasing NGF (EC-NGF) were surgically implanted bilaterally in the basal forebrain of six AD patients for 12 months and cholinergic markers in CSF were analyzed.

RESULTS

Activities of both enzymes were altered after 12 months. In particular, the activity of soluble ChAT showed high correlation with cognition, CSF tau and amyloid-β, in vivo cerebral glucose utilization and nicotinic binding sites, and morphometric and volumetric magnetic resonance imaging measures.

DISCUSSION

A clear pattern of association is demonstrated showing a proof-of-principle effect on CSF cholinergic markers, suggestive of a beneficial EC-NGF implant therapy.

Crosstalk Among Disrupted Glutamatergic and Cholinergic Homeostasis and Inflammatory Response in Mechanisms Elicited by Proline in Astrocytes

Hyperprolinemias are inherited disorder of proline (Pro) metabolism. Patients affected may present neurological manifestations, but the mechanisms of neural excitotoxicity elicited by hyperprolinemia are far from being understood. Considering that the astrocytes are important players in neurological disorders, the aim of the present work was to study the effects 1 mM Pro on glutamatergic and inflammatory parameters in cultured astrocytes from cerebral cortex of rats, exploring some molecular mechanisms underlying the disrupted homeostasis of astrocytes exposed to this toxic Pro concentration. We showed that cortical astrocytes of rats exposed to 1 mM Pro presented significantly elevated extracellular glutamate and glutamine levels, suggesting glutamate excitotoxicity. The excess of glutamate elicited by Pro together with increased glutamate uptake and upregulated glutamine synthetase (GS) activity supported misregulated glutamate homeostasis in astrocytic cells. High Pro levels also induced production/release of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. We also evidenced misregulation of cholinergic anti-inflammatory system with increased acetylcholinesterase (AChE) activity and decreased acetylcholine (ACh) levels, contributing to the inflammatory status in Pro-treated astrocytes. Our findings highlighted a crosstalk among disrupted glutamate homeostasis, cholinergic mechanisms, and inflammatory cytokines, since ionotropic (DL-AP5 and CNQX) and metabotropic (MCPG and MPEP) glutamate antagonists were able to restore the extracellular glutamate and glutamine levels; downregulate TNFα and IL6 production/release, modulate GS and AChE activities; and restore ACh levels. Otherwise, the non-steroidal anti-inflammatory drugs nimesulide, acetylsalicylic acid, ibuprofen, and diclofenac sodium decreased the extracellular glutamate and glutamine levels, downregulated GS and AChE activities, and restored ACh levels in Pro-treated astrocytes. Altogether, our results evidence that the vulnerability of metabolic homeostasis in cortical astrocytes might have important implications in the neurotoxicity of Pro.

Fibrillar β-amyloid 1-42 alters cytokine secretion, cholinergic signalling and neuronal differentiation

Adult neurogenesis is impaired by inflammatory processes, which are linked to altered cholinergic signalling and cognitive decline in Alzheimer's disease. In this study, we investigated how amyloid beta (Aβ)-evoked inflammatory responses affect the generation of new neurons from human embryonic stem (hES) cells and the role of cholinergic signalling in regulating this process. The hES were cultured as neurospheres and exposed to fibrillar and oligomeric Aβ(1-42) (Aβf, AβO) or to conditioned medium from human primary microglia activated with either Aβ(1-42) or lipopolysaccharide. The neurospheres were differentiated for 29 days in vitro and the resulting neuronal or glial phenotypes were thereafter assessed. Secretion of cytokines and the enzymes acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and choline acetyltransferase (ChAT) involved in cholinergic signalling was measured in medium throughout the differentiation. We report that differentiating neurospheres released various cytokines, and exposure to Aβf, but not AβO, increased the secretion of IL-6, IL-1β and IL-2. Aβf also influenced the levels of AChE, BuChE and ChAT in favour of a low level of acetylcholine. These changes were linked to an altered secretion pattern of cytokines. A different pattern was observed in microglia activated by Aβf, demonstrating decreased secretion of TNF-α, IL-1β and IL-2 relative to untreated cells. Subsequent exposure of differentiating neurospheres to Aβf or to microglia-conditioned medium decreased neuronal differentiation and increased glial differentiation. We suggest that a basal physiological secretion of cytokines is involved in shaping the differentiation of neurospheres and that Aβf decreases neurogenesis by promoting a microenvironment favouring hypo-cholinergic signalling and gliogenesis.

Microwave-assisted synthesis of novel purine nucleosides as selective cholinesterase inhibitors

A series of new purine nucleosides bearingd-glucosyl,d-mannosyl andd-galactosyl groups was synthesized. Selective inhibition of butyryl- or acetylcholinesterase could be tuned by purine substitution and glycosyl moiety. The 2-acetamidopurine nucleoside exhibiting ad-mannosyl group, α-configuration and N⁷-ligation was the most active and selective competitive inhibitor of butyrylcholinesterase.

Unbiased expression mapping identifies a link between the complement and cholinergic systems in the rat central nervous system

The complement system is activated in a wide spectrum of CNS diseases and is suggested to play a role in degenerative phenomena such as elimination of synaptic terminals. Still, little is known of mechanisms regulating complement activation in the CNS. Loss of synaptic terminals in the spinal cord after an experimental nerve injury is increased in the inbred DA strain compared with the PVG strain and is associated with expression of the upstream complement components C1q and C3, in the absence of membrane attack complex activation and neutrophil infiltration. To further dissect pathways regulating complement expression, we performed genome-wide expression profiling and linkage analysis in a large F2(DA × PVG) intercross, which identified quantitative trait loci regulating expression of C1qa, C1qb, C3, and C9. Unlike C1qa, C1qb, and C9, which all displayed distinct coregulation with different cis-regulated C-type lectins, C3 was regulated in a coexpression network immediately downstream of butyrylcholinesterase. Butyrylcholinesterase hydrolyses acetylcholine, which exerts immunoregulatory effects partly through TNF-α pathways. Accordingly, increased C3, but not C1q, expression was demonstrated in rat and mouse glia following TNF-α stimulation, which was abrogated in a dose-dependent manner by acetylcholine. These findings demonstrate new pathways regulating CNS complement expression using unbiased mapping in an experimental in vivo system. A direct link between cholinergic activity and complement activation is supported by in vitro experiments. The identification of distinct pathways subjected to regulation by naturally occurring genetic variability is of relevance for the understanding of disease mechanisms in neurologic conditions characterized by neuronal injury and complement activation.

Regulated Extracellular Choline Acetyltransferase Activity- The Plausible Missing Link of the Distant Action of Acetylcholine in the Cholinergic Anti-Inflammatory Pathway

Acetylcholine (ACh), the classical neurotransmitter, also affects a variety of nonexcitable cells, such as endothelia, microglia, astrocytes and lymphocytes in both the nervous system and secondary lymphoid organs. Most of these cells are very distant from cholinergic synapses. The action of ACh on these distant cells is unlikely to occur through diffusion, given that ACh is very short-lived in the presence of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), two extremely efficient ACh-degrading enzymes abundantly present in extracellular fluids. In this study, we show compelling evidence for presence of a high concentration and activity of the ACh-synthesizing enzyme, choline-acetyltransferase (ChAT) in human cerebrospinal fluid (CSF) and plasma. We show that ChAT levels are physiologically balanced to the levels of its counteracting enzymes, AChE and BuChE in the human plasma and CSF. Equilibrium analyses show that soluble ChAT maintains a steady-state ACh level in the presence of physiological levels of fully active ACh-degrading enzymes. We show that ChAT is secreted by cultured human-brain astrocytes, and that activated spleen lymphocytes release ChAT itself rather than ACh. We further report differential CSF levels of ChAT in relation to Alzheimer's disease risk genotypes, as well as in patients with multiple sclerosis, a chronic neuroinflammatory disease, compared to controls. Interestingly, soluble CSF ChAT levels show strong correlation with soluble complement factor levels, supporting a role in inflammatory regulation. This study provides a plausible explanation for the long-distance action of ACh through continuous renewal of ACh in extracellular fluids by the soluble ChAT and thereby maintenance of steady-state equilibrium between hydrolysis and synthesis of this ubiquitous cholinergic signal substance in the brain and peripheral compartments. These findings may have important implications for the role of cholinergic signaling in states of inflammation in general and in neurodegenerative disease, such as Alzheimer's disease and multiple sclerosis in particular.