Genetic predisposition to adverse consequences of anti-cholinesterases in 'atypical' BCHE carriers

Investigating biomarkers of exposure to jet aircraft oil fumes using mass spectrometry

Most commercial passenger jet aircraft use compressed engine air as a source for ventilation and cabin pressurization onboard. This"bleed air" design means that engine oil and/or hydraulic fluid can contaminate the ventilation supply air during otherwise normal flights, exposing onboard crewmembers and passengers to the fumes. The oils and hydraulic fluids contain a complex mixture of triaryl phosphates (TAPs) and decomposition products. Although the health and flight safety consequences of inhaling these fumes have been widely documented, measures of onboard inhalation exposure have been lacking. An approach is presented for documenting exposure to engine oil fumes by using high-resolution mass spectrometry (MS) to monitor and quantify post-translational modifications of subjects' butyrylcholinesterase (BChE) that are consistent with exposure to the engine oil TAPs. We hypothesized that plasma from exposed individuals would show modifications or adducts on the active site serine (Ser198) of BChE. Plasma BChE from 82 exposed subjects was purified to near homogeneity and concentrated using antibodies immobilized on paramagnetic beads. The purified BChE was eluted at low pH, digested with trypsin, and analyzed by liquid chromatography (LC)-MS. In subjects reporting onboard oil fume exposures, the most consistent adduct modifying the Ser198-containing tryptic peptide had a mass value of +154.0031 Da. The normalized peak area (NPA) of the +154Da modification was determined by comparing the relative MS1 intensities of the +154Da-modified Ser198 containing peptide to the total observable peptides containing the active site, including missed cleavages. Notably, adducts from in vitro exposures of bioactivated TAPs to purified BChE conducted in this study (i.e., +80Da, +156Da, +170Da, and +186Da) as well as adducts reported in other earlier in vitro studies (i.e., +65Da, +80Da, +91Da, +107Da, +165Da, +180Da, +181Da, and +277Da) were not detected in exposed subjects. Of the 82 subjects in this study, the average NPA of +154Da-Ser198 resulted from fume event exposures that pre-dated 2012 (N=54; 0.46-17.8,X - = 3.93 ) was 7.8 times higher than control subjects. These data are uncorrected for the time lag between the reported exposure and the blood draw. Samples from the remaining 28 subjects with exposures from 2016-2024 showed only the 154Da modification at background levels (0.24-1.13;X - = 0.50 ), as confirmed in control plasma samples from individuals who had not flown in at least three months. The observed reduction in the 154Da adduct over time in exposed individuals is likely a function of the change in the formulation of the OP blends added to engine oils during the course of the study. Further investigation into other protein biomarkers and adducts correlated with exposure to the current oil additives and hydraulic fluid fumes on aircraft is warranted. The most satisfactory solution would be to eliminate the exposure hazard by implementing bleed-free systems or, at a minimum, to develop less toxic oil formulations, suitable bleed air filters, and modified designs.

Modification in ICU design may influence circadian serum cholinesterase activities: a proof-of-concept pilot study

BACKGROUND

Deficits in cholinergic function are assumed to cause cognitive decline. Studies have demonstrated that changes in serum cholinesterase activities are associated with a higher incidence of delirium in critically ill patients. Additionally, basic research indicates that the cholinergic and circadian systems are interconnected, with each system influencing the functionality of the other. This data analysis of a proof-of-concept pilot study investigates whether modification in ICU design, including dynamic light therapy, may influence the circadian oscillation of serum cholinesterase activities.

METHODS

We enrolled adult critically ill patients who were on mechanical ventilation and had an anticipated ICU stay of at least 48 h. The patients were treated in either modified or standard ICU rooms. The modified rooms received extensive architectural modifications, including a new dynamic lighting system. Serum acetylcholinesterase and butyrylcholinesterase activities were measured every four hours for up to three 24-h assessment periods.

RESULTS

We included 64 patients in the data analysis (n = 34 patients in modified rooms, n = 30 in standard rooms). The median values of serum acetylcholinesterase and butyrylcholinesterase activities showed different patterns. Acetylcholinesterase activities differed significantly between the groups during the first assessment period (p = 0.04) and the second assessment period (p = 0.045). The intensity of light, as quantified by the effective circadian irradiance, significantly influenced the activities of acetylcholinesterase and butyrylcholinesterase throughout all assessment periods for patients in both groups (p < 0.001). The analysis showed significant interaction (p < 0.001), indicating that the differences in acetylcholinesterase and butyrylcholinesterase activities between the groups were inconsistent over time but apparent during specific periods of the day.

CONCLUSION

Implementing a comprehensive set of changes to the design of ICU rooms, including a dynamic lighting system, may influence the course of the activity patterns of acetylcholinesterase and butyrylcholinesterase in critically ill patients. Modifications to environmental factors could potentially offer neuroprotective benefits and facilitate the realignment of circadian rhythms within the cholinergic system. Clinical trial registration ClinicalTrials.gov: NCT02143661. Registered May 21, 2014.

Association of deployment characteristics and exposures with persistent ill health among 1990-1991 Gulf War veterans in the VA Million Veteran Program

BACKGROUND

Veterans of the 1990-1991 Gulf War have experienced excess health problems, most prominently the multisymptom condition Gulf War illness (GWI). The Department of Veterans Affairs (VA) Cooperative Studies Program #2006 "Genomics of Gulf War Illness in Veterans" project was established to address important questions concerning pathobiological and genetic aspects of GWI. The current study evaluated patterns of chronic ill health/GWI in the VA Million Veteran Program (MVP) Gulf War veteran cohort in relation to wartime exposures and key features of deployment, 27-30 years after Gulf War service.

METHODS

MVP participants who served in the 1990-1991 Gulf War completed the MVP Gulf War Era Survey in 2018-2020. Survey responses provided detailed information on veterans' health, Gulf War exposures, and deployment time periods and locations. Analyses determined associations of three defined GWI/ill health outcomes with Gulf War deployment characteristics and exposures.

RESULTS

The final cohort included 14,103 veterans; demographic and military characteristics of the sample were similar to the full population of U.S. 1990-1991 Gulf War veterans. Overall, a substantial number of veterans experienced chronic ill health, as indicated by three defined outcomes: 49% reported their health as fair or poor, 31% met Centers for Disease Control and Prevention criteria for severe GWI, and 20% had been diagnosed with GWI by a healthcare provider. Health outcomes varied consistently with veterans' demographic and military characteristics, and with exposures during deployment. All outcomes were most prevalent among youngest veterans (< 50 years), Army and Marine Corps veterans, enlisted personnel (vs. officers), veterans located in Iraq and/or Kuwait for at least 7 days, and veterans who remained in theater from January/February 1991 through the summer of 1991. In multivariable models, GWI/ill health was most strongly associated with three exposures: chemical/biological warfare agents, taking pyridostigmine bromide pills, and use of skin pesticides.

CONCLUSIONS

Results from this large cohort indicate that GWI/chronic ill health continues to affect a large proportion of Gulf War veterans in patterns associated with 1990-1991 Gulf War deployment and exposures. Findings establish a foundation for comprehensive evaluation of genetic factors and deployment exposures in relation to GWI risk and pathobiology.

Evaluation of a Gene-Environment Interaction of PON1 and Low-Level Nerve Agent Exposure with Gulf War Illness: A Prevalence Case-Control Study Drawn from the U.S. Military Health Survey's National Population Sample

BACKGROUND

Consensus on the etiology of 1991 Gulf War illness (GWI) has been limited by lack of objective individual-level environmental exposure information and assumed recall bias.

OBJECTIVES

We investigated a prestated hypothesis of the association of GWI with a gene-environment (GxE) interaction of the paraoxonase-1 (PON1) Q192R polymorphism and low-level nerve agent exposure.

METHODS

A prevalence sample of 508 GWI cases and 508 nonpaired controls was drawn from the 8,020 participants in the U.S. Military Health Survey, a representative sample survey of military veterans who served during the Gulf War. The PON1 Q192R genotype was measured by real-time polymerase chain reaction (RT-PCR), and the serum Q and R isoenzyme activity levels were measured with PON1-specific substrates. Low-level nerve agent exposure was estimated by survey questions on having heard nerve agent alarms during deployment.

RESULTS

The GxE interaction of the Q192R genotype and hearing alarms was strongly associated with GWI on both the multiplicative [prevalence odds ratio (POR) of the interaction=3.41; 95% confidence interval (CI): 1.20, 9.72] and additive (synergy index=4.71; 95% CI: 1.82, 12.19) scales, adjusted for measured confounders. The Q192R genotype and the alarms variable were independent (adjusted POR in the controls=1.18; 95% CI: 0.81, 1.73; p=0.35), and the associations of GWI with the number of R alleles and quartiles of Q isoenzyme were monotonic. The adjusted relative excess risk due to interaction (aRERI) was 7.69 (95% CI: 2.71, 19.13). Substituting Q isoenzyme activity for the genotype in the analyses corroborated the findings. Sensitivity analyses suggested that recall bias had forced the estimate of the GxE interaction toward the null and that unmeasured confounding is unlikely to account for the findings. We found a GxE interaction involving the Q-correlated PON1 diazoxonase activity and a weak possible GxE involving the Khamisiyah plume model, but none involving the PON1 R isoenzyme activity, arylesterase activity, paraoxonase activity, butyrylcholinesterase genotypes or enzyme activity, or pyridostigmine.

DISCUSSION

Given gene-environment independence and monotonicity, the unconfounded aRERI>0 supports a mechanistic interaction. Together with the direct evidence of exposure to fallout from bombing of chemical weapon storage facilities and the extensive toxicologic evidence of biochemical protection from organophosphates by the Q isoenzyme, the findings provide strong evidence for an etiologic role of low-level nerve agent in GWI. https://doi.org/10.1289/EHP9009.

Multi-biomarker approach to assess chromium, pH and temperature toxicity in fish

Chromium (Cr) is considered as the most common ubiquitous pollutant for aquatic animals including fish. An experiment was conducted to determine the acute and chronic toxicity of Cr, pH and high temperature in Anabas testudineus. Lethal concentration (LC₅₀) of Cr alone was determined as 55.02 mg L^-1, Cr and low pH 48.19 mg L^-1 and Cr, low pH and high temperature 47.16 mg L^-1. The chronic toxicity of low dose of Cr, pH and high temperature (1/10th and 1/20th of LC₅₀) was designed to execute the experiment for 72 days. The stress enzymes and biomarkers were determined viz. superoxide dismutase, catalase, glutathione peroxidase, glutathione-s-transferase, lipid peroxide, acetylcholine esterase, cortisol, HSP-70, blood glucose, aspartate amino transferase, alanine amino transferase and malate dehydrogenase, lactate dehydrogenase, ATPase and genotoxicity in this study. We had also studied the integrated biomarker response (IBR), which revealed that Cr toxicity enhanced with concurrent exposure to pH and high temperature. All the biochemical attributes were significantly altered with exposure to Cr alone and with low pH and high temperature except gill SOD. Further, thermal tolerance was also determined, and results revealed that thermal tolerance was significantly reduced with exposure to Cr alone and Cr and low pH exposure in A. testudineus. The present study concluded that, the chronic toxicity of Cr is enhanced with low pH and high temperature and it has led to understanding the multi-approach of Cr toxicity which affect, stress biomarkers, cellular metabolic stress and thermal tolerance of A. testudineus.

Cholinesterase activity in serum during general anesthesia in patients with or without vascular disease

Maintaining hemodynamic stability during the induction and maintenance of anesthesia is one of the challenges of the anesthesiologist. Patients with vascular disease are at increased risk of instability due to imbalance between the sympathetic and parasympathetic parts of the autonomic nervous system, a balance accessible by serum cholinesterase activity. We aim to characterize the dynamics of cholinesterase activity in patients undergoing general anesthesia (GA) and surgery. This was a prospective study of 57 patients undergoing ambulatory or vascular surgery under GA. Cholinesterase activity was measured before the induction of anesthesia, after 15 min and at the end of surgery by calculating the capacity of serum acetylcholinesterase (AChE) and butyrylcholinesterase to hydrolyze AcetylThioCholine. Data on atherosclerotic disease, anesthesia management were analyzed. Both AChE and total cholinergic status (CS) decreased significantly after GA induction at 15 min and even more so by the end of surgery. Vascular surgery patients had lower baseline cholinesterase activity compared to ambulatory surgery patients. Patients requiring intraoperative administration of phenylephrine for hemodynamic support (21.1%) had a significantly lower level of AChE and CS compared to untreated patients. Our findings serve as a mirror to the sympathetic/parasympathetic imbalance during GA, with a marked decrease in the parasympathetic tone. The data of a subgroup analysis show a correlation between low cholinesterase activity and an increase in the need for hemodynamic support.

Radiological, Chemical, and Pharmacological Cholinergic System Parameters and Neurocognitive Disorders in Older Presurgical Adults

BACKGROUND

A pre-existing neurocognitive disorder (NCD) is a relevant factor for the outcome of surgical patients. To improve understanding of these conditions, we investigated the association between parameters of the cholinergic system and NCD.

METHOD

This investigation is part of the BioCog project (www.biocog.eu), which is a prospective multicenter observational study including patients aged 65 years and older scheduled for elective surgery. Patients with a Mini-Mental State Examination (MMSE) score ≤23 points were excluded. Neurocognitive disorder was assessed according to the fifth Diagnostic and Statistical Manual of Mental Disorders criteria. The basal forebrain cholinergic system volume (BFCSV) was assessed with magnetic resonance imaging, the peripheral cholinesterase (ChE) activities with point-of-care measurements, and anticholinergic load by analyzing the long-term medication with anticholinergic scales (Anticholinergic Drug Scale [ADS], Anticholinergic Risk Scale [ARS], Anticholinergic Cognitive Burden Scale [ACBS]). The associations of BFCSV, ChE activities, and anticholinergic scales with NCD were studied with logistic regression analysis, adjusting for confounding factors.

RESULTS

A total of 797 participants (mean age 72 years, 42% females) were included. One hundred and eleven patients (13.9%) fulfilled criteria for mild NCD and 82 patients (10.3%) for major NCD criteria. We found that AcetylChE activity was associated with major NCD (odds ratio [95% confidence interval]: [U/gHB] 1.061 [1.010, 1.115]), as well as ADS score ([points] 1.353 [1.063, 1.723]) or ARS score, respectively ([points] 1.623 [1.100, 2.397]) with major NCD. However, we found no association between BFCSV or ButyrylChE activity with mild or major NCD.

CONCLUSIONS

AcetylChE activity and anticholinergic load were associated with major NCD. Future research should focus on the association of the cholinergic system and the development of postoperative delirium and postoperative NCD.

Central and peripheral anti-inflammatory effects of acetylcholinesterase inhibitors

Acetylcholinesterase (AChE) inhibitors modulate acetylcholine hydrolysis and hence play a key role in determining the cholinergic tone and in implementing its impact on the cholinergic blockade of inflammatory processes. Such inhibitors may include rapidly acting small molecule AChE-blocking drugs and poisonous anti-AChE insecticides or war agent inhibitors which penetrate both body and brain. Notably, traumatized patients may be hyper-sensitized to anti-AChEs due to their impaired cholinergic tone, higher levels of circulation pro-inflammatory cytokines and exacerbated peripheral inflammatory responses. Those largely depend on the innate-immune system yet reach the brain via vagus pathways and/or disrupted blood-brain-barrier. Other regulators of the neuro-inflammatory cascade are AChE-targeted microRNAs (miRs) and synthetic chemically protected oligonucleotide blockers thereof, whose size prevents direct brain penetrance. Nevertheless, these larger molecules may exert parallel albeit slower inflammatory regulating effects on brain and body tissues. Additionally, oligonucleotide aptamers interacting with innate immune Toll-Like Receptors (TLRs) may control inflammation through diverse routes and in different rates. Such aptamers may compete with the action of both small molecule inhibitors and AChE-inhibiting miRs in peripheral tissues including muscle and intestine. However, rapid adaptation processes, visualized in neuromuscular junctions enable murine survival under otherwise lethal anti-cholinesterase exposure; and both miR inhibitors and TLR-modulating aptamers may exert body-brain signals protecting experimental mice from acute inflammation. The complex variety of AChE inhibiting molecules identifies diverse body-brain communication pathways which may rapidly induce long-lasting central reactions to peripheral stressful and inflammatory insults in both mice and men. This article is part of the special issue entitled 'Acetylcholinesterase Inhibitors: From Bench to Bedside to Battlefield'.

Cholinesterase's activities of infected mice by Brucella ovis

The role of cholinesterase in inflammatory reactions has been described in several infectious diseases. However, in Brucella spp. this has not yet been studied. Therefore, the objective of this study was to evaluate whether experimental infection by Brucella ovis alters the cholinergic activity in pro- or anti-inflammatory responses to the disease. For the study 48 mice were used, 24 infected by B. ovis and 24 non-infected. We collected samples of whole blood on days 7, 15, 30 and 60 post-infection (PI) by B. ovis. Acetylcholinesterase (AChE) activity in the blood increased on days 15 and 60 PI (P < 0.05). Butyrylcholinesterase (BChE) activity in serum increased on days 7 and 60 PI (P < 0.05). An increase in serum free radical levels occurred on days 7, 15 and 60 PI (P < 0.05), and consequently superoxide dismutase activity increased on day 15 PI (P < 0.05). A reduction in catalase activity occurred when the infection became chronic (60 PI). The increase in AChE and BChE characterized a pro-inflammatory response, since these enzymes regulate levels of acetylcholine (ACh) and butyrylcholine (BuSCh), molecules with anti-inflammatory properties. Therefore, with the increase of cholinesterase activity, there was an extracellular reduction of ACh, an inhibitor of several inflammatory mediators. This proinflammatory response of B. ovis infection leads to oxidative stress, and consequently to cellular damage.

Butyrylcholinesterase-a potential plasma biomarker in manganese-induced neurobehavioral changes

Groundwater particularly drinking water contamination with metals has created an environmental disaster in Bangladesh. Manganese (Mn), an essential trace element, plays a key role in the development and function of the brain. Excess Mn exposure is reported to be associated with complex neurological disorders. Here, we have found a notably large extent of Mn above the permissive limit in the tube-well water of Rajshahi and Naogaon districts in Bangladesh. Higher levels of Mn in hair and nail samples, and a decreasing level of butyrylcholinesterase (BChE) activity were detected in plasma samples of the human subjects recruited from Naogaon district. Mn concentrations in water, hair, and nails were negatively correlated with the plasma BChE levels in Mn-exposed populations. To compare and validate these human studies, an animal model was used to determine the in vivo effects of Mn on neurobehavioral changes and blood BChE levels. In elevated plus maze, the time spent was significantly reduced in open arms and increased in closed arms of Mn-exposed mice compared to control group. The mean latency time to find the platform was declined significantly in control mice compared to Mn-treated group during 7 days in Morris water maze test, and Mn-exposed group also spent significantly less time in the desired quadrant as compared to the control group in probe trial. BChE activity was significantly reduced in Mn-exposed mice compared to control mice. Taken together, these results suggest that plasma BChE levels may serve as reliable biomarker of Mn-induced neurotoxicity related to behavioral changes.

Gastrointestinal neuroimmune disruption in a mouse model of Gulf War illness

Gulf War illness (GWI) is a chronic multisymptom disorder that is prominent in Gulf War veterans. Major unexplained symptoms of GWI include functional gastrointestinal disorders and undiagnosed illnesses, including neurologic disorders. Exposure to the antinerve gas drug pyridostigmine bromide (PB) is linked to the development of GWI, but the exact mechanisms remain unclear. Here, we tested the hypothesis that PB alters gut function by disrupting the neural and immune systems of the intestine. We exposed male and female mice to physiologically comparable amounts of PB that match the dose, route, and time frame of exposure experienced by Gulf War veterans and assessed the acute and chronic impacts on gastrointestinal functions, the functional architecture of the enteric nervous system, and immune responses in the gut and brain. Exposure to PB drove acute alterations to colonic motility and structure in both male and female mice that transitioned to chronic changes in gut functions. PB drove acute alterations to enteric neural and glial activity, glial reactivity, and neuron survival with glial reactivity persisting into the chronic phase in male mice. Despite having no effect on colonic permeability, exposure to PB caused major shifts in the expression of proinflammatory cytokines and chemokines in the colon and brain that suggest immunosuppressive effects. Interestingly, immune disruption was still evident in the colon and brain in female animals at 1 mo following exposure to PB. Together, our results show that the paradigm of PB exposure experienced by veterans of the Persian Gulf War contributes to long-lasting pathophysiology by driving enteric neuroinflammation, promoting immunosuppression, and altering functional anatomy of the colon in a sex-dependent manner.-Hernandez, S., Fried, D. E., Grubišić, V., McClain, J. L., Gulbransen, B. D. Gastrointestinal neuroimmune disruption in a mouse model of Gulf War illness.

Biochemical Analysis and Association of Butyrylcholinesterase SNPs rs3495 and rs1803274 with Substance Abuse Disorder

Addiction is a complex mental and behavioral disorder that changes the neurochemistry and physiology of the brain. Genetics also plays a significant role in the pathophysiology of addiction. Butyrylcholinesterase (BChE), a cholinergic enzyme, has been implicated in the metabolism of various drugs, including cocaine, and an association between single-nucleotide polymorphisms (SNPs) of the butyrylcholinesterase gene (BCHE) and neuronal disorders has been reported. We report here the first investigation to be conducted on the status of BChE activity and the potential association of two BCHE gene SNPs, rs3495 (c.*189G > A) and rs1803274 (c.1699G>A, p.Ala567Thr, K-variant), with addiction vulnerability in heroin, hashish and polydrug users. Seventy-five individuals with an addiction to heroin, hashish and/or polydrug use were recruited to this study. BChE levels in the plasma were determined by Ellman's principle. SNPs were genotyped by standard procedures, followed by Sanger sequencing. Plasma BChE levels were found to be significantly higher (p ≤ 0.05) in addicts (mean ± standard error of the mean 0.031 ± 0.004 μmol/L/min; 95% confidence interval [CI] 0.024-0.038) than in non-addicts (controls) (0.014 ± 0.001 μmol/L/min; 95% CI 0.012-0.017). Statistical significant differences were also observed between the addicted cohorts. A statistically significant association for both SNPs (rs3495 and rs1803274) was not observed in addicted subjects tested in the dominant, recessive and allele genetic models, but trends of variations of the rs3495 risk G allele were noted. The authors conclude that BChE plays significant roles in addiction pathophysiology as increased BChE activity in blood samples obtained from the cohorts with addiction was evident. Further studies in this direction may provide novel approaches for the treatment of addiction, but studies with a larger sample size and different ethnic groups are warranted for broader conclusions to be drawn.

Personalized genetics of the cholinergic blockade of neuroinflammation

Acetylcholine signaling is essential for cognitive functioning and blocks inflammation. To maintain homeostasis, cholinergic signaling is subjected to multi‐leveled and bidirectional regulation by both proteins and non‐coding microRNAs (‘CholinomiRs’). CholinomiRs coordinate the cognitive and inflammatory aspects of cholinergic signaling by targeting major cholinergic transcripts including the acetylcholine hydrolyzing enzyme acetylcholinesterase (AChE). Notably, AChE inhibitors are the only currently approved line of treatment for Alzheimer's disease patients. Since cholinergic signaling blocks neuroinflammation which is inherent to Alzheimer's disease, genomic changes modifying AChE's properties and its susceptibility to inhibitors and/or to CholinomiRs regulation may affect the levels and properties of inflammasome components such as NLRP3. This calls for genomic‐based medicine approaches based on genotyping of both coding and non‐coding single nucleotide polymorphisms (SNPs) in the genes involved in cholinergic signaling. An example is a SNP in a recognition element for the primate‐specific microRNA‐608 within the 3′ untranslated region of the AChE transcript. Carriers of the minor allele of that SNP present massively elevated brain AChE levels, increased trait anxiety and inflammation, accompanied by perturbed CholinomiR‐608 regulatory networks and elevated prefrontal activity under exposure to stressful insults. Several additional SNPs in the AChE and other cholinergic genes await further studies, and might likewise involve different CholinomiRs and pathways including those modulating the initiation and progression of neurodegenerative diseases. CholinomiRs regulation of the cholinergic system thus merits in‐depth interrogation and is likely to lead to personalized medicine approaches for achieving better homeostasis in health and disease.

This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.

Naturally Occurring Genetic Variants of Human Acetylcholinesterase and Butyrylcholinesterase and Their Potential Impact on the Risk of Toxicity from Cholinesterase Inhibitors

Acetylcholinesterase (AChE) is the physiologically important target for organophosphorus toxicants (OP) including nerve agents and pesticides. Butyrylcholinesterase (BChE) in blood serves as a bioscavenger that protects AChE in nerve synapses from inhibition by OP. Mass spectrometry methods can detect exposure to OP by measuring adducts on the active site serine of plasma BChE. Genetic variants of human AChE and BChE do exist, but loss of function mutations have been identified only in the BCHE gene. The most common AChE variant, His353Asn (H322N), also known as the Yt blood group antigen, has normal AChE activity. The most common BChE variant, Ala567Thr (A539T) or the K-variant in honor of Werner Kalow, has 33% reduced plasma BChE activity. The genetic variant most frequently associated with prolonged response to muscle relaxants, Asp98Gly (D70G) or atypical BChE, has reduced activity and reduced enzyme concentration. Early studies in young, healthy males, performed at a time when it was legal to test nerve agents in humans, showed that individuals responded differently to the same low dose of sarin with toxic symptoms ranging in severity from minimal to moderate. Additionally, animal studies indicated that BChE protects from toxicants that have a higher reactivity with AChE than with BChE (e.g., nerve agents) but not from toxicants that have a higher reactivity with BChE than with AChE (e.g., OP pesticides). As a corollary, we hypothesize that individuals with genetic variants of BChE may be at increased risk of toxicity from nerve agents but not from OP pesticides.

Review : The Vicious Circle of Stress and Anticholinesterase Responses

After either acute psychological stress or exposure to acetylcholinesterase (AChE) inhibitors, long-lasting deleterious changes of a similar nature occur in the mammalian brain. We explored the molecular and neurophysiological mechanisms preceding these convergent delayed consequences in vivo and in perfused hippocampal brain slices. In stressed mice, we observed a disruption of the blood-brain barrier, which leads to efficient brain penetrance of anti-AChEs. This increase in penetrance of anti-AChEs, and consequently in acetylcholine (ACh) levels, induces a cascade of c-fos-mediated transcriptional responses dependent on intracellular Ca2+ accumulation. Consequently, the capacity for synthesis and vesicle packaging of ACh is suppressed simultaneously with enhanced AChE production that potentiates ACh hydrolysis. This bimodal decrease in ACh bioavailability, which is independent of the hypothalamic-pituitary-adrenal axis, then ter minates the initial neurophysiological excitation. In vivo, this AChE overexpression leads to enzyme accu mulation that is evident for more than 80 hr. The overexpressed enzyme can protect the brain from sustained hyperexcitability and from increased susceptibility to seizure activity and neuronal toxicity. However, exper imental accumulation of AChE in brain neurons through transgenic manipulations leads to a slowly pro gressive deterioration in cognitive and neuromotor faculties. The transcriptional consequences of stress and anti-AChEs may therefore be beneficial in the short term but deleterious in the long term. NEURO SCIENTIST 5:173-183, 1999

Activity and polymorphisms of butyrylcholinesterase in a Polish population

Butyrylcholinesterase (BChE) activity assay and inhibitor phenotyping can help to identify individuals at risk of prolonged paralysis following the administration of neuromuscular blocking agents, like succinylcholine, pesticides and nerve agents. In this study, the activity of BChE and its sensitivity to inhibition by dibucaine and fluoride was evaluated in 1200 Polish healthy individuals. In addition, molecular analysis of all exons, exon-intron boundaries and the 3'UTR sequence of the BCHE gene was performed in a group of 72 subjects with abnormal BChE activity (<2000 U/L and >5745 U/L) or with DN (Dibucaine Number) or FN (Fluoride-Number) values outside the reference range (DN < 78 and FN < lower than wild type). In a studied group, BChE activity range was similar to those observed in other populations. BChE activity screening allowed to detect UA and UF phenotypes in 26 (2.2%) and 15 (1.2%) individuals, respectively. Observed UA or UF phenotypes were confirmed by direct sequencing and heterozygous c.293A > G or c.1253G > T substitutions were identified in all cases. Nine out of 18 (50%) individuals with BChE activity below 2000 U/L had a mutation in 5'UTR (32G/A), intron 2 (c.1518-121T/C) or exon 4 (c.1699G/A; the K variant mutation). Majority of the individuals with BChE activity ≥6000 U/L were wild type. To summarize, the range of BChE activity in a Polish population is similar to those observed in other countries. We conclude that the BChE phenotyping assay is a reliable method for identification of individuals with the UA and UF genotypes.

Weakened Cholinergic Blockade of Inflammation Associates with Diabetes-Related Depression

Emerging evidence demonstrates association of depression with both immune malfunctioning and worsened course of diverse aging-related diseases, but there is no explanation for the pathway(s) controlling this dual association. Here, we report that in post-reproductive and evolutionarily -blind" years, depression may weaken pathogen-host defense, compatible with the antagonistic pleiotropy hypothesis. In 15,532 healthy volunteers, depression scores associated with both inflammatory parameters and with increased circulation cholinesterase activities, implicating debilitated cholinergic blockade of inflammation as an underlying mechanism; furthermore, depression, inflammation and cholinesterase activities all increased with aging. In the entire cohort, combined increases in inflammation and the diabetic biomarker hemoglobin A1c associated with elevated depression. Moreover, metabolic syndrome patients with higher risk of diabetes showed increased cholinesterase levels and pulse values, and diabetic patients presented simultaneous increases in depression, inflammation and circulation cholinesterase activities, suggesting that cholinergic impairment precedes depression. Our findings indicate that dysfunctioning cholinergic regulation weakens the otherwise protective link between depression and pathogen-host defense, with global implications for aging-related diseases.

Comparison of 5 monoclonal antibodies for immunopurification of human butyrylcholinesterase on Dynabeads: KD values, binding pairs, and amino acid sequences

Human butyrylcholinesterase (HuBChE) is a stoichiometric bioscavenger of nerve agents and organophosphorus pesticides. Mass spectrometry methods detect stable nerve agent adducts on the active site serine of HuBChE. The first step in sample preparation is immunopurification of HuBChE from plasma. Our goal was to identify monoclonal antibodies that could be used to immunopurify HuBChE on Dynabeads Protein G. Mouse anti-HuBChE monoclonal antibodies were obtained in the form of ascites fluid, dead hybridoma cells stored frozen at -80 °C for 30 years, or recently frozen hybridoma cells. RNA from 4 hybridoma cell lines was amplified by PCR for determination of their nucleotide and amino acid sequences. Full-length light and heavy chains were expressed, and the antibodies purified from culture medium. A fifth monoclonal was purchased. The 5 monoclonal antibodies were compared for ability to capture HuBChE from human plasma on Dynabeads Protein G. In addition, they were evaluated for binding affinity by Biacore and ELISA. Epitope mapping by pairing analysis was performed on the Octet Red96 instrument. The 5 monoclonal antibodies, B2 12-1, B2 18-5, 3E8, mAb2, and 11D8, had similar KD values of 10(-9) M for HuBChE. Monoclonal B2 18-5 outperformed the others in the Dynabeads Protein G assay where it captured 97% of the HuBChE in 0.5 ml plasma. Pairing analysis showed that 3E8 and B2 12-1 share the same epitope, 11D8 and B2 18-5 share the same epitope, but mAb2 and B2 12-1 or mAb2 and 3E8 bind to different epitopes on HuBChE. B2 18-5 was selected for establishment of a stable CHO cell line for production of mouse anti-HuBChE monoclonal.

Serum Total Cholinesterase Activity on Admission Is Associated with Disease Severity and Outcome in Patients with Traumatic Brain Injury

BACKGROUND

Traumatic brain injury (TBI) is one of the leading causes of neurological disability. In this retrospective study, serum total cholinesterase (ChE) activities were analyzed in 188 patients for diagnostic as well as predictive values for mortality.

METHODS AND FINDINGS

Within 72 hours after injury, serum ChE activities including both acetylcholinesterase and butyrylcholinesterase were measured. Disease severity was evaluated with Acute Physiology and Chronic Health Evaluation (APACHE) II score, Glasgow Coma Score, length of coma, post-traumatic amnesia and injury feature. Neurocognitive and functional scores were assessed using clinical records. Of 188 patients, 146 (77.7%) survived and 42 (22.3%) died within 90 days. Lower ChE activities were noted in the non-survivors vs. survivors (5.94±2.19 vs. 7.04±2.16 kU/L, p=0.023), in septic vs. non-infected patients (5.93±1.89 vs. 7.31±2.45 kU/L, p=0.0005) and in patients with extremely severe injury vs. mild injury (6.3±1.98 vs. 7.57±2.48 kU/L, p=0.049). The trajectories of serum ChE levels were also different between non-survivors and survivors, septic and non-infected patients, mild and severely injured patients, respectively. Admission ChE activities were closely correlated with blood cell counts, neurocognitive and functional scores both on admission and at discharge. Receiver operating characteristic analysis showed that the area under the curve for ChE was inferior to that for either APACHE II or white blood cell (WBC) count. However, at the optimal cutoff value of 5 kU/L, the sensitivity of ChE for correct prediction of 90-day mortality was 65.5% and the specificity was 86.4%. Kaplan-Meier analysis showed that lower ChE activity (<5 kU/L) was more closely correlated with poor survival than higher ChE activity (>5 kU/L) (p=0.04). After adjusting for other variables, ChE was identified as a borderline independent predictor for mortality as analyzed by Binary logistic regression (P=0.078).

CONCLUSIONS

Lowered ChE activity measured on admission appears to be associated with disease severity and outcome for TBI patients.

Gut feeling: MicroRNA discriminators of the intestinal TLR9-cholinergic links

The intestinal tissue notably responds to stressful, cholinergic and innate immune signals by microRNA (miRNA) changes, but whether and how those miRNA regulators modify the intestinal cholinergic and innate immune pathways remained unexplored. Here, we report changes in several miRNA regulators of cholinesterases (ChEs) and correspondingly modified ChE activities in intestine, splenocytes and the circulation of mice exposed to both stress and canonical or alternative Toll-Like Receptor 9 (TLR9) oligonucleotide (ODN) aptamer activators or blockers. Stressful intraperitoneal injection of saline, the anti-inflammatory TLR9 agonist mEN101 aptamer or the inflammation-activating TLR9 aptamer ODN 1826 all increased the expression of the acetylcholinesterase (AChE)-targeting miR-132. In comparison, mEN101 but neither ODN 1826 nor saline injections elevated intestinal miR-129-5p, miR-186 and miR-200c, all predicted to target both AChE and the homologous enzyme butyrylcholinesterase (BChE). In cultured immune cells, BL-7040, the human counterpart of mEN101, reduced AChE activity reflecting inflammatory reactions in a manner preventable by the TLR9 blocking ODN 2088. Furthermore, the anti-inflammatory BL-7040 TLR9 aptamer caused reduction in nitric oxide and AChE activity in both murine splenocytes and human mononuclear cells at molar concentrations four orders of magnitude lower than ODN 1826. Our findings demonstrate differential reaction of cholinesterase-targeting miRNAs to distinct TLR9 challenges, indicating upstream miRNA co-regulation of the intestinal alternative NFκB pathway and cholinergic signaling. TLR9 aptamers may hence potentiate miRNA regulation that enhances cholinergic signaling and the resolution of inflammation, which opens new venues for manipulating bowel diseases.

Butyrylcholinesterase genotype and enzyme activity in relation to Gulf War illness: preliminary evidence of gene-exposure interaction from a case-control study of 1991 Gulf War veterans

BACKGROUND

Epidemiologic studies have implicated wartime exposures to acetylcholinesterase (AChE)-inhibiting chemicals as etiologic factors in Gulf War illness (GWI), the multisymptom condition linked to military service in the 1991 Gulf War. It is unclear, however, why some veterans developed GWI while others with similar exposures did not. Genetic variants of the enzyme butyrylcholinesterase (BChE) differ in their capacity for metabolizing AChE-inhibiting chemicals, and may confer differences in biological responses to these compounds. The current study assessed BChE enzyme activity and BChE genotype in 1991 Gulf War veterans to evaluate possible association of this enzyme with GWI.

METHODS

This case-control study evaluated a population-based sample of 304 Gulf War veterans (144 GWI cases, meeting Kansas GWI criteria, and 160 controls). BChE enzyme activity levels and genotype were compared, overall, in GWI cases and controls. Potential differences in risk associated with cholinergic-related exposures in theater were explored using stratified analyses to compare associations between GWI and exposures in BChE genetic and enzyme activity subgroups.

RESULTS

Overall, GWI cases and controls did not differ by mean BChE enzyme activity level or by BChE genotype. However, for the subgroup of Gulf War veterans with less common, generally less active, BChE genotypes (K/K, U/AK, U/A, A/F, AK/F), the association of wartime use of pyridostigmine bromide (PB) with GWI (OR=40.00, p=0.0005) was significantly greater than for veterans with the more common U/U and U/K genotypes (OR=2.68, p=0.0001).

CONCLUSIONS

Study results provide preliminary evidence that military personnel with certain BChE genotypes who used PB during the 1991 Gulf War may have been at particularly high risk for developing GWI. Genetic differences in response to wartime exposures are potentially important factors in GWI etiology and should be further evaluated in conjunction with exposure effects.

Fear and C-reactive protein cosynergize annual pulse increases in healthy adults

Recent international terror outbreaks notably involve long-term mental health risks to the exposed population, but whether physical health risks are also anticipated has remained unknown. Here, we report fear of terror-induced annual increases in resting heart rate (pulse), a notable risk factor of all-cause mortality. Partial least squares analysis based on 325 measured parameters successfully predicted annual pulse increases, inverse to the expected age-related pulse decline, in approximately 4.1% of a cohort of 17,380 apparently healthy active Israeli adults. Nonbiased hierarchical regression analysis among 27 of those parameters identified pertinent fear of terror combined with the inflammatory biomarker C-reactive protein as prominent coregulators of the observed annual pulse increases. In comparison, basal pulse primarily depended on general physiological parameters and reduced cholinergic control over anxiety and inflammation, together indicating that consistent exposure to terror threats ignites fear-induced exacerbation of preexisting neuro-immune risks of all-cause mortality.

The assessment of cholinesterase from the liver of Puntius javanicus as detection of metal ions

Crude extract of ChE from the liver of Puntius javanicus was purified using procainamide-sepharyl 6B. S-Butyrylthiocholine iodide (BTC) was selected as the specific synthetic substrate for this assay with the highest maximal velocity and lowest biomolecular constant at 53.49 µmole/min/mg and 0.23 mM, respectively, with catalytic efficiency ratio of 0.23. The optimum parameter was obtained at pH 7.5 and optimal temperature in the range of 25 to 30°C. The effect of different storage condition was assessed where ChE activity was significantly decreased after 9 days of storage at room temperature. However, ChE activity showed no significant difference when stored at 4.0, 0, and −25°C for 15 days. Screening of heavy metals shows that chromium, copper, and mercury strongly inhibited P. javanicus ChE by lowering the activity below 50%, while several pairwise combination of metal ions exhibited synergistic inhibiting effects on the enzyme which is greater than single exposure especially chromium, copper, and mercury. The results showed that P. javanicus ChE has the potential to be used as a biosensor for the detection of metal ions.

Decline in serum cholinesterase activities predicts 2-year major adverse cardiac events

Parasympathetic activity influences long-term outcome in patients with cardiovascular disease, but the underlying mechanism(s) linking parasympathetic activity and the occurrence of major adverse cardiovascular events (MACEs) are incompletely understood. The aim of this pilot study was to evaluate the association between serum cholinesterase activities as parasympathetic biomarkers and the risk for the occurrence of MACEs. Cholinergic status was determined by measuring the cumulative capacity of serum acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) to hydrolyze the AChE substrate acetylthiocholine. Cholinergic status was evaluated in randomly selected patients undergoing cardiac catheterization. The patients were divided into two groups of 100 patients in each group, with or without occurrence of MACEs during a follow-up period of 40 months. Cox regression models adjusted for potential clinical, metabolic and inflammatory confounders served to evaluate association with clinical outcome. We found that patients with MACE presented lower cholinergic status and AChE values at catheterization (1,127 ± 422 and 359 ± 153 nmol substrate hydrolyzed per minute per milliliter, respectively) than no-MACE patients (1,760 ± 546 and 508 ± 183 nmol substrate hydrolyzed per minute per milliliter, p < 0.001 and p < 0.001, respectively), whose levels were comparable to those of matched healthy controls (1,622 ± 303 and 504 ± 126 nmol substrate hydrolyzed per minute per milliliter, respectively). In a multivariate analysis, patients with AChE or total cholinergic status values below median showed conspicuously elevated risk for MACE (hazard ratio 1.85 [95% confidence interval [CI] 1.09-3.15, p = 0.02] and 2.21 [95% CI 1.22-4.00, p = 0.009]) compared with those above median, even after adjusting for potential confounders. We conclude that parasympathetic dysfunction expressed as reduced serum AChE and AChE activities in patients compared to healthy controls can together reflect impaired parasympathetic activity. This impairment predicts the risk of MACE up to 40 months in such patients. Monitoring these parasympathetic parameters might help in the risk stratification of patients with cardiovascular disease.

Cholinesterases as biomarkers for parasympathetic dysfunction and inflammation-related disease

Accumulating evidence suggests parasympathetic dysfunction and elevated inflammation as underlying processes in multiple peripheral and neurological diseases. Acetylcholine, the main parasympathetic neurotransmitter and inflammation regulator, is hydrolyzed by the two closely homologous enzymes, acetylcholinesterase and butyrylcholinesterase (AChE and BChE, respectively), which are also expressed in the serum. Here, we consider the potential value of both enzymes as possible biomarkers in diseases associated with parasympathetic malfunctioning. We cover the modulations of cholinesterase activities in inflammation-related events as well as by cholinesterase-targeted microRNAs. We further discuss epigenetic control over cholinesterase gene expression and the impact of single-nucleotide polymorphisms on the corresponding physiological and pathological processes. In particular, we focus on measurements of circulation cholinesterases as a readily quantifiable readout for changes in the sympathetic/parasympathetic balance and the implications of changes in this readout in health and disease. Taken together, this cumulative know-how calls for expanding the use of cholinesterase activity measurements for both basic research and as a clinical assessment tool.

Cholinergic involvement and manipulation approaches in multiple system disorders

Within the autonomic system, acetylcholine signaling contributes simultaneously and interactively to cognitive, behavioral, muscle and immune functions. Therefore, manipulating cholinergic parameters such as the activities of the acetylcholine hydrolyzing enzymes in body fluids or the corresponding transcript levels in blood leukocytes can change the global status of the autonomic system in treated individuals. Specifically, cholinesterase activities are subject to rapid and effective changes. The enzyme activity baseline increases with age and body mass index and depends on gender and ethnic origin. Also, the corresponding DNA (for detecting mutations) and RNA (for measuring specific mRNA transcripts) of cholinergic genes present individual variability. In leukocytes, acetylcholine inhibits the production of pro-inflammatory cytokines, suggesting relevance of cholinergic parameters to both the basal levels and to disease-induced inflammation. Inversely, acetylcholine levels increase under various stress stimuli, inducing changes in autonomic system molecules (e.g., pro-inflammatory cytokines) which can penetrate the brain; therefore, manipulating these levels can also effect brain reactions, mainly of anxiety, depression and pain. Additionally, neurodegenerative diseases often involve exacerbated inflammation, depression and anxiety, providing a focus interest group for cholinergic manipulations. In Alzheimer's disease, the systemic cholinergic impairments reflect premature death of cholinergic neurons. The decline of cholinesterases in the serum of Parkinson's disease and post- stroke patients, discovery of the relevant microRNAs and the growing range of use of anticholinesterase medications all call for critical re-inspection of established and novel approaches for manipulating cholinergic parameters.

Why has butyrylcholinesterase been retained? Structural and functional diversification in a duplicated gene

While acetylcholinesterase (EC 3.1.1.7) has a clearly defined role in neurotransmission, the functions of its sister enzyme butyrylcholinesterase (EC 3.1.1.8) are more obscure. Numerous mutations, many inactivating, are observed in the human butyrylcholinesterase gene, and the butyrylcholinesterase knockout mouse has an essentially normal phenotype, suggesting that the enzyme may be redundant. Yet the gene has survived for many millions of years since the duplication of an ancestral acetylcholinesterase early in vertebrate evolution. In this paper, we ask the questions: why has butyrylcholinesterase been retained, and why are inactivating mutations apparently tolerated? Butyrylcholinesterase has diverged both structurally and in terms of tissue and cellular expression patterns from acetylcholinesterase. Butyrylcholinesterase-like activity and enzymes have arisen a number of times in the animal kingdom, suggesting the usefulness of such enzymes. Analysis of the published literature suggests that butyrylcholinesterase has specific roles in detoxification as well as in neurotransmission, both in the brain, where it appears to control certain areas and functions, and in the neuromuscular junction, where its function appears to complement that of acetylcholinesterase. An analysis of the mutations in human butyrylcholinesterase and their relation to the enzyme's structure is shown. In conclusion, it appears that the structure of butyrylcholinesterase's catalytic apparatus is a compromise between the apparently conflicting selective demands of a more generalised detoxifier and the necessity for maintaining high catalytic efficiency. It is also possible that the tolerance of mutation in human butyrylcholinesterase is a consequence of the detoxification function. Butyrylcholinesterase appears to be a good example of a gene that has survived by subfunctionalisation.

Quantum dot labeling of butyrylcholinesterase maintains substrate and inhibitor interactions and cell adherence features

Butyrylcholinesterase (BChE) is the major acetylcholine hydrolyzing enzyme in peripheral mammalian systems. It can either reside in the circulation or adhere to cells and tissues and protect them from anticholinesterases, including insecticides and poisonous nerve gases. In humans, impaired cholinesterase functioning is causally involved in many pathologies, including Alzheimer's and Parkinson's diseases, trait anxiety, and post stroke conditions. Recombinant cholinesterases have been developed for therapeutic use; therefore, it is important to follow their in vivo path, location, and interactions. Traditional labeling methods, such as fluorescent dyes and proteins, generally suffer from sensitivity to environmental conditions, from proximity to different molecules or special enzymes which can alter them, and from relatively fast photobleaching. In contrast, emerging development in synthesis and surface engineering of semiconductor nanocrystals enable their use to detect and follow molecules in biological milieus at high sensitivity and in real time. Therefore, we developed a platform for conjugating highly purified recombinant human BChE dimers (rhBChE) to CdSe/CdZnS quantum dots (QDs). We report the development and characterization of highly fluorescent aqueous soluble QD-rhBChE conjugates, present maintenance of hydrolytic activity, inhibitor sensitivity, and adherence to the membrane of cultured live cells of these conjugates, and outline their advantageous features for diverse biological applications.

Evolution of acetylcholinesterase and butyrylcholinesterase in the vertebrates: an atypical butyrylcholinesterase from the Medaka Oryzias latipes

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are thought to be the result of a gene duplication event early in vertebrate evolution. To learn more about the evolution of these enzymes, we expressed in vitro, characterized, and modeled a recombinant cholinesterase (ChE) from a teleost, the medaka Oryzias latipes. In addition to AChE, O. latipes has a ChE that is different from either vertebrate AChE or BChE, which we are classifying as an atypical BChE, and which may resemble a transitional form between the two. Of the fourteen aromatic amino acids in the catalytic gorge of vertebrate AChE, ten are conserved in the atypical BChE of O. latipes; by contrast, only eight are conserved in vertebrate BChE. Notably, the atypical BChE has one phenylalanine in its acyl pocket, while AChE has two and BChE none. These substitutions could account for the intermediate nature of this atypical BChE. Molecular modeling supports this proposal. The atypical BChE hydrolyzes acetylthiocholine (ATCh) and propionylthiocholine (PTCh) preferentially but butyrylthiocholine (BTCh) to a considerable extent, which is different from the substrate specificity of AChE or BChE. The enzyme shows substrate inhibition with the two smaller substrates but not with the larger substrate BTCh. In comparison, AChE exhibits substrate inhibition, while BChE does not, but may instead show substrate activation. The atypical BChE from O. latipes also shows a mixed pattern of inhibition. It is effectively inhibited by physostigmine, typical of all ChEs. However, although the atypical BChE is efficiently inhibited by the BChE-specific inhibitor ethopropazine, it is not by another BChE inhibitor, iso-OMPA, nor by the AChE-specific inhibitor BW284c51. The atypical BChE is found as a glycophosphatidylinositol-anchored (GPI-anchored) amphiphilic dimer (G(2) (a)), which is unusual for any BChE. We classify the enzyme as an atypical BChE and discuss its implications for the evolution of AChE and BChE and for ecotoxicology.

Serum cholinesterase activities distinguish between stroke patients and controls and predict 12-month mortality

To date there is no diagnostic biomarker for mild stroke, although elevation of inflammatory biomarkers has been reported at early stages. Previous studies implicated acetylcholinesterase (AChE) involvement in stroke, and circulating AChE activity reflects inflammatory response, since acetylcholine suppresses inflammation. Therefore, carriers of polymorphisms that modify cholinergic activity should be particularly susceptible to inflammatory damage. Our study sought diagnostic values of AChE and Cholinergic Status (CS, the total capacity for acetylcholine hydrolysis) in suspected stroke patients. For this purpose, serum cholinesterase activities, butyrylcholinesterase-K genotype and inflammatory biomarkers were determined in 264 ischemic stroke patients and matched controls during the acute phase. AChE activities were lower (P<0.001), and butyrylcholinesterase activities were higher in patients than in controls (P=0.004). When normalized to sampling time from stroke occurrence, both cholinergic parameters were correlated with multiple inflammatory biomarkers, including fibrinogen, interleukin-6 and C-reactive protein (r=0.713, r=0.607; r=0.421, r=0.341; r=0.276, r=0.255; respectively; all P values<0.001). Furthermore, very low AChE activities predicted subsequent nonsurvival (P=0.036). Also, carriers of the unstable butyrylcholinesterase-K variant were more abundant among patients than controls, and showed reduced activity (P<0.001). Importantly, a cholinergic score combining the two cholinesterase activities discriminated between 94.3% matched pairs of patients and controls, compared with only 75% for inflammatory measures. Our findings present the power of circulation cholinesterase measurements as useful early diagnostic tools for the occurrence of stroke. Importantly, these were considerably more distinctive than the inflammatory biomarkers, albeit closely associated with them, which may open new venues for stroke diagnosis and treatment.

Expression of three naturally occurring genetic variants (G75R, E90D, I99M) of the BCHE gene of human butyrylcholinesterase

The present paper examined the effects of three non synonymous BCHE mutations (G75R, E90D and /99M) on enzyme kinetic parameters obtained after the expression of the respective recombinant BChEs. The respective nucleotide substitution that characterizes each of the three variants was introduced into BCHE cDNA by site directed mutagenesis and transfected into human embryonic kidney 293 T cells and Chinese hamster ovary cells (for E90D). BChE catalysed hydrolysis of butyrylthiocoline (BTC) was measured by Ellman method. The expression results showed that: (1) the activity of the G75R enzyme represents approximately 45% of the wild-type activity, whereas that of the I99M enzyme does not differ from the wild-type; (2) the E90D enzyme presents a silent phenotype; disruption of the salt bridge between E90 and R42 may cause the enzyme to be rapidly degraded inside the cells. In homozygous form the E90D enzyme may confer increased susceptibility to succinylcholine, but may delay cognitive impairment in aged individuals. BChE genotyping may become important for estimating prognosis, and the knowledge of the genetic variants of BChE in a particular population may be useful for carrying out the genotyping assays.

Cholinergic status modulations in human volunteers under acute inflammation

Cholinergic Status, the total soluble circulation capacity for acetylcholine hydrolysis, was tested for putative involvement in individual variabilities of the recruitment of immune cells in response to endotoxin challenge. Young (average age 26) and elderly (average age 70) volunteers injected with either Escherichia coli endotoxin or saline on two different occasions were first designated Enhancers and Suppressors if they showed increase or decrease, respectively, in plasma acetylcholinesterase (AChE) activity 1.5 h after endotoxin administration compared to saline. Enhancers showed significant co-increases in plasma butyrylcholinesterase (BChE) and paraoxonase (PON1) activities, accompanied by rapid recovery of lymphocyte counts. Young Enhancers alone showed pronounced post-exposure increases in the pro-inflammatory cytokine interleukin-6 (IL-6), and upregulation of the normally rare, stress-induced AChE-R variant, suggesting age-associated exhaustion of the cholinergic effects on recruiting innate immune reactions to endotoxin challenge. Importantly, IL-6 injected to young volunteers or administered in vitro to primary mononuclear blood cells caused upregulation of AChE, but not BChE or PON1, excluding it from being the sole cause for this extended response. Interestingly, Suppressors but not Enhancers showed improved post-exposure working memory performance, indicating that limited cholinergic reactions may be beneficial for cognition. Our findings establish Cholinergic Status modulations as early facilitators and predictors of individual variabilities in the peripheral response to infection.

Effect of acetylcholinesterase inhibition with pyridostigmine on cardiac parasympathetic function in sedentary adults and trained athletes

Heart rate variability and postexercise heart rate recovery are used to assess cardiac parasympathetic tone in human studies, but in some cases these indexes appear to yield discordant information. We utilized pyridostigmine, an acetylcholinesterase inhibitor that selectively augments the parasympathetic efferent signal, to further characterize parasympathetic regulation of rest and postexercise heart rate. We measured time- and frequency-domain indexes of resting heart rate variability and postexercise heart rate recovery in 10 sedentary adults and 10 aerobically trained athletes after a single oral dose of pyridostigmine (30 mg) and matching placebo in randomized, double-blind, crossover trial. In sedentary adults, pyridostigmine decreased resting heart rate [from 66.7 (SD 12.6) to 58.1 beats/min (SD 7.6), P = 0.005 vs. placebo] and increased postexercise heart rate recovery at 1 min [from 40.7 (SD 10.9) to 45.1 beats/min (SD 8.8), P = 0.02 vs. placebo]. In trained athletes, pyridostigmine did not change resting heart rate or postexercise heart rate recovery when compared with placebo. Time- and frequency-domain indexes of resting heart rate variability did not differ after pyridostigmine versus placebo in either cohort and were not significantly associated with postexercise heart rate recovery in either cohort. The divergent effects of pyridostigmine on resting and postexercise measures of cardiac parasympathetic function in sedentary subjects confirm that these measures characterize distinct aspects of cardiac parasympathetic regulation. The lesser effect of pyridostigmine on either measure of cardiac parasympathetic tone in the trained athletes indicates that the enhanced parasympathetic tone associated with exercise training is at least partially attributable to adaptations in the efferent parasympathetic pathway.

Effects of combined exposure to pyridostigmine bromide and shaker stress on acoustic startle response, pre-pulse inhibition and open field behavior in mice

The present study investigated the effect of combined exposure of pyridostigmine bromide (PB) and chronic shaker stress on acoustic startle responses (ASR), pre-pulse inhibition (PPI) and open field behavior of adult C57BL/6J mice. PB (10 mg kg(-1) day(-1) for 7 days) or saline was administered subcutaneously using osmotic Alzet minipumps implanted under the skin on the back of the mice. At the same time, the mice were exposed to 7 days of intermittent shaker stress. They were tested for ASR (100 dB and 120 dB stimuli) and PPI (70 dB + 100 dB and 70 dB + 120 dB) in the acoustic startle monitor system. The mice were assessed during the shaker stress on days 2 and 7 and 7, 14, 21 and 28 days after discontinuation of treatment. Separate groups of mice were tested in the open field in 15 min sessions on days 1, 3 and 6 during shaker stress and PB treatment. Exposure of mice to PB resulted in an exaggerated ASR, reduced PPI and non-significant decrease in locomotor activity. These behavioral changes were apparent only during exposure to PB. Repeated shaker stress did not have any effect on sensorimotor functions or open field behavior of mice. There was no prolonged or delayed effect of PB and/or stress on individual behavioral variables. The study found C57BL/6J mice to be behaviorally sensitive to PB treatment.

Butyrylcholinesterase attenuates amyloid fibril formation in vitro

In Alzheimer's disease, both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) colocalize with brain fibrils of amyloid-beta (Abeta) peptides, and synaptic AChE-S facilitates fibril formation by association with insoluble Abeta fibrils. Here, we report that human BChE and BSP41, a synthetic peptide derived from the BChE C terminus, inversely associate with the soluble Abeta conformers and delay the onset and decrease the rate of Abeta fibril formation in vitro, at a 1:100 BChE/Abeta molar ratio and in a dose-dependent manner. The corresponding AChE synthetic peptide (ASP)40 peptide, derived from the homologous C terminus of synaptic human (h)AChE-S, failed to significantly affect Abeta fibril formation, attributing the role of enhancing this process to an AChE domain other than the C terminus. Circular dichroism and molecular modeling confirmed that both ASP40 and BChE synthetic peptide (BSP)41 are amphipathic alpha-helices. However, ASP40 shows symmetric amphipathicity, whereas BSP41 presented an aromatic tryptophan residue in the polar side of the C terminus. That this aromatic residue is causally involved in the attenuating effect of BChE was further supported by mutagenesis experiments in which (W8R) BSP41 showed suppressed capacity to attenuate fibril formation. In Alzheimer's disease, BChE may have thus acquired an inverse role to that of AChE by adopting imperfect amphipathic characteristics of its C terminus.

Antisense inhibition of acetylcholinesterase gene expression for treating cognition deficit in Alzheimer's disease model mice

To examine whether the selected antisense oligodeoxynucleotides (AS-ODN) targeting against human brain acetylcholinesterase (AChE) mRNA could improve the cognitive deficit in the Alzheimer's disease (AD) model mice induced by amyloid-beta peptide (Abeta), we determined the time-effect relationship of AChE activity and the learning and memory after AS-ODN delivery. The results showed that the AChE activity decreased gradually along with time, initiating at 8 h and lasting 42 h. The time-effect curves of acetylcholine (ACh) behaved consistency with that of AChE activity. The animal cognition studies showed that in step-through test, the error number of the AS-ODN-treated AD model mice was significantly decreased, and the memory retention was increased. In the water maze performance, the swimming time obviously shortened. Our results indicated that antisense therapy is of potential use in the treatment of cognitive deficit in the Abeta model mice.

Neurological status of Australian veterans of the 1991 Gulf War and the effect of medical and chemical exposures

BACKGROUND

Since the 1991 Gulf War, concerns have been voiced about the effects on the health of veterans of Gulf War related medical and chemical exposures.

METHODS

Our cross-sectional study compared 1424 male Australian Gulf War veterans and a randomly sampled military comparison group (n = 1548). A postal questionnaire asked about the presence of current neurological type symptoms, medically diagnosed neurological conditions, and medical and chemical exposures. A neurological examination was performed as part of a physical assessment.

RESULTS

Veterans have a higher prevalence of neurological type symptoms (ratio of means 1.4, 95% confidence interval (CI) 1.2-1.5). Although the odds ratio (OR) of lower limb neurological type symptoms and signs in veterans compared with the comparison group was increased (OR = 1.6, 95% CI 1.0-2.7), it was of borderline significance, and there was no difference between groups according to a Neuropathy Score based on neurological signs alone (ratio of means 1.1, 95% CI 0.9-1.3). The increased OR of neurological type symptoms and signs suggestive of a central nervous system disorder (OR = 1.8, 95% CI 1.0-3.1) was also of borderline significance. Veterans were not more likely to have self-reported medically diagnosed neurological conditions, or to have neurological type symptoms and signs suggestive of an anterior horn cell disorder (OR = 0.9, 95% CI 0.5-1.6). The total number of neurological type symptoms reported by veterans, but not the Neuropathy Score, was associated with Gulf War related exposures including immunizations and pyridostigmine bromide in dose-response relationships, anti-biological warfare tablets, solvents, pesticides, and insect repellents.

CONCLUSIONS

This study shows increased reporting of neurological type symptoms in Gulf War veterans, but no evidence for increased neurological effects based on objective physical signs. There may be a number of factors, including information bias, relating to increased neurological type symptom reporting in veterans.

Acetylcholinesterase/paraoxonase interactions increase the risk of insecticide-induced Parkinson's disease

Exposure to agricultural insecticides, together with yet incompletely understood predisposing genotype/phenotype elements, notably increase the risk of Parkinson's disease. Here, we report findings attributing the increased risk in an insecticide-exposed rural area in Israel to interacting debilitating polymorphisms in the ACHE/PON1 locus and corresponding expression variations. Polymorphisms that debilitate PON1 activity and cause impaired AChE overproduction under anticholinesterase exposure were strongly overrepresented in patients from agriculturally exposed areas, indicating that they confer risk of Parkinson's disease. Supporting this notion, serum AChE and PON1 activities were both selectively and significantly lower in patients than in healthy individuals and in carriers of the risky polymorphisms as compared with other Parkinsonian patients. Our findings suggest that inherited interactive weakness of AChE and PON1 expression increases the insecticide-induced occurrence of Parkinson's disease.

Acetylcholinesterase/paraoxonase genotype and expression predict anxiety scores in Health, Risk Factors, Exercise Training, and Genetics study

Anxiety involves complex, incompletely understood interactions of genomic, environmental, and experience-derived factors, and is currently being measured by psychological criteria. Here, we report previously nonperceived interrelationships between expression variations and nucleotide polymorphisms of the chromosome 7q21-22 acetylcholinesterase-paraoxonase 1 (ACHE-PON1) locus with the trait- and state-anxiety measures of 461 healthy subjects from the Health, Risk Factors, Exercise Training, and Genetics Family Study. The AChE protein controls the termination of the stress-enhanced acetylcholine signaling, whereas the PON protein displays peroxidase-like activity, thus protecting blood proteins from oxidative stress damages. Serum AChE and PON enzyme activities were both found to be affected by demographic parameters, and showed inverse, reciprocal associations with anxiety measures. Moreover, the transient scores of state anxiety and the susceptibility score of trait anxiety both appeared to be linked to enzyme activities. This finding supported the notion of corresponding gene expression relationships. Parallel polymorphisms in the ACHE and PON1 genes displayed apparent associations with both trait- and state-anxiety scores. Our findings indicate that a significant source of anxiety feelings involves inherited and acquired parameters of acetylcholine regulation that can be readily quantified, which can help explaining part of the human variance for state and trait anxiety.

Creatine phosphate kinase elevations signaling muscle damage following exposures to anticholinesterases: 2 sentinel patients

In this study, the authors describe 2 patients who experienced confirmed exposures to anticholinesterases that commenced in the 1970s. Subsequently, elevations in creatine phosphate kinase (CPK) were initially detected more than a decade following the first acute exposure. Beginning in the early 1980s, the patients suffered from progressive generalized muscle weakness, chronic fatigue, myopathy, neuropathy, and severe neurobehavioral impairments. Previous occupational exposures included pyridostigmine, as well as isopropyl methylphosphonofluoridate (percutaneous lethal dose [LD50] < 28 mg/kg body weight), and 1 patient had exposure to agricultural organophosphates. The authors hypothesize that the workers' CPK elevations, first detected more than a decade following acute exposures to anticholinesterases, were sentinel events for impending muscle damage and necrosis. Many Gulf War veterans with Gulf War disease who reported exposures to anticholinesterases 1 decade earlier currently suffer from vague neuromuscular and cognitive impairments. Therefore, medical programs for Gulf War veterans with Gulf War Syndrome should include surveillance for elevated CPK, abnormalities of neuromuscular conduction, and genetic susceptibility, and they should promote therapeutic trials for palliation.

Pyridostigmine enhances glutamatergic transmission in hippocampal CA1 neurons

Pyridostigmine, a carbamate acetylcholinesterase (AChE) inhibitor, is routinely employed in the treatment of the autoimmune disease myasthenia gravis. Due to its positively charged ammonium group, under normal conditions pyridostigmine cannot cross the blood-brain barrier (BBB) and penetrate the brain. However, several studies have suggested that under conditions in which the BBB is disrupted, pyridostigmine enters the brain, changes cortical excitability, and leads to long-lasting alterations in gene expression. The aim of this study was to characterize the mechanisms underlying pyridostigmine-induced changes in the excitability of central neurons. Using whole cell intracellular recordings in hippocampal neurons we show that pyridostigmine decreases repetitive firing adaptation and increases the appearance of excitatory postsynaptic potentials. In voltage clamp recordings, both pyridostigmine and acetylcholine (ACh) increased the frequency but not the amplitude of excitatory postsynaptic currents. These effects were reversible upon the administration of the muscarinic receptor antagonist, atropine, and were not blocked by tetrodotoxin. We conclude that pyridostigmine, by increasing free ACh levels, causes muscarinic-dependent enhancement of excitatory transmission. This mechanism may explain central side effects previously attributed to this drug as well as the potency of AChE inhibitors, including nerve-gas agents and organophosphate pesticides, in the initiation of cortical synchronization, epileptic discharge, and excitotoxic damage.