Recombinant human butyrylcholinesterase from milk of transgenic animals to protect against organophosphate poisoning

Low levels of endogenous cholinesterases support the choice of cows, sheep and goats for the transgenic expression of human butyrylcholinesterase in milk

Butyrylcholinesterase purified from human plasma (Hu BChE) as well as recombinant (r) Hu BChE are candidate enzymes that can protect humans from toxicity of organophosphorus compounds (OPs). Domestic animals such as cows, pigs, sheep, and goats have been used for the transgenic expression of a variety of valuable therapeutic proteins. Indeed, rHu BChE was successfully expressed in the milk of transgenic goats, but the presence of any endogenous cholinesterases (ChE) in milk would interfere with the isolation of expressed rHu BChE. The aim of this study was to determine the presence of endogenous ChEs in bovine, ovine, caprine, and porcine milk to determine the suitability of these species for the production of rHu BChE. Using acetyl- and butyryl- thiocholine as substrates, ChE activity (2-4 U/mL) was detected in pig milk only. ChE activities in milk from other animals were <0.01 U/mL and could only be detected following enrichment on procainamide-Sepharose gel. Two different methods based on measuring activity in the presence of acetylcholinesterase (AChE)- or BChE- specific inhibitors were used to estimate the proportions of AChE and BChE activities in enriched milk. Monoclonal antibodies (MAbs), against fetal bovine serum AChE that recognize AChEs from ruminants only, were also used to confirm the identity of AChEs. While bovine and ovine milk contain both AChE and BChE activities, caprine and porcine milk contain predominantly BChE activity. The presence of very low ChE activity supports the choice of cows, sheep, and goats for the transgenic expression of rHu BChE in milk.

Chemical, Physical, and Toxicological Properties of V-Agents

V-agents are exceedingly toxic organophosphate nerve agents. The most widely known V-agents are the phosphonylated thiocholines VX and VR. Nonetheless, other V-subclasses have been synthesized. Here, a holistic overview of V-agents is provided, where these compounds have been categorized based on their structures to facilitate their study. A total of seven subclasses of V-agents have been identified, including phospho(n/r)ylated selenocholines and non-sulfur-containing agents, such as VP and EA-1576 (EA: Edgewood Arsenal). Certain V-agents have been designed through the conversion of phosphorylated pesticides to their respective phosphonylated analogs, such as EA-1576 derived from mevinphos. Further, this review provides a description of their production, physical properties, toxicity, and stability during storage. Importantly, V-agents constitute a percutaneous hazard, while their high stability ensures the contamination of the exposed area for weeks. The danger of V-agents was highlighted in the 1968 VX accident in Utah. Until now, VX has been used in limited cases of terrorist attacks and assassinations, but there is an increased concern about potential terrorist production and use. For this reason, studying the chemistry of VX and other less-studied V-agents is important to understand their properties and develop potential countermeasures.

Synthesis, in vitro biological screening and docking study of benzo[d]oxazole bis Schiff base derivatives as a potent anti-Alzheimer agent

We have synthesized benzo[d]oxazole derivatives (1-21) through a multistep reaction. Alteration in the structure of derivatives was brought in the last step via using various substituted aromatic aldehydes. In search of an anti-Alzheimer agent, all derivatives were evaluated against acetylcholinesterase and butyrylcholinesterase enzyme under positive control of standard drug donepezil (IC₅₀ = 0.016 ± 0.12 and 4.5 ± 0.11 µM) respectively. In case of acetylcholinesterase enzyme inhibition, derivatives 8, 9 and 18 (IC₅₀ = 0.50 ± 0.01, 0.90 ± 0.05 and 0.3 ± 0.05 µM) showed very promising inhibitory potentials. While in case of butyrylcholinesterase enzyme inhibition, most of the derivatives like 6, 8, 9, 13, 15, 18 and 19 (IC₅₀ = 2.70 ± 0.10, 2.60 ± 0.10, 2.20 ± 0.10, 4.25 ± 0.10, 3.30 ± 0.10, 0.96 ± 0.05 and 3.20 ± 0.10 µM) displayed better inhibitory potential than donepezil. Moreover, derivative 18 is the most potent one among the series in both inhibitions. The binding interaction of derivatives with the active gorge of the enzyme was confirmed via a docking study. Furthermore, the binding interaction between derivatives and the active site of enzymes was correlated through the SAR study. Structures of all derivatives were confirmed through spectroscopic techniques such as ¹H-NMR, ¹³C-NMR and HREI-MS, respectively.Communicated by Ramaswamy H. Sarma.

Design and production strategies for developing a recombinant butyrylcholinesterase medical countermeasure for Organophosphorus poisoning

Organophosphorus nerve agents represent a serious chemical threat due to their ease of production and scale of impact. The recent use of the nerve agent Novichok has re-emphasised the need for broad-spectrum medical countermeasures (MCMs) to these agents. However, current MCMs are limited. Plasma derived human butyrylcholinesterase (huBChE) is a promising novel bioscavenger MCM strategy, but is prohibitively expensive to isolate from human plasma at scale. Efforts to produce recombinant huBChE (rBChE) in various protein expression platforms have failed to achieve key critical attributes of huBChE such as circulatory half-life. These proteins often lack critical features such as tetrameric structure and requisite post-translational modifications. This review evaluates previous attempts to generate rBChE and assesses recent advances in mammalian cell expression and protein engineering strategies that could be deployed to achieve the required half-life and yield for a viable rBChE MCM. This includes the addition of a proline-rich attachment domain, fusion proteins, post translational modifications, expression system selection and optimised downstream processes. Whilst challenges remain, a combinatorial approach of these strategies demonstrates potential as a technically feasible approach to achieving a bioactive and cost effective bioscavenger MCM.

Structural Modifications on Chalcone Framework for Developing New Class of Cholinesterase Inhibitors

Due to the multifaceted pharmacological activities of chalcones, these scaffolds have been considered one of the most privileged frameworks in the drug discovery process. Structurally, chalcones are α, β-unsaturated carbonyl functionalities with two aryl or heteroaryl units. Amongst the numerous pharmacological activities explored for chalcone derivatives, the development of novel chalcone analogs for the treatment of Alzheimer's disease (AD) is among the research topics of most interest. Chalcones possess numerous advantages, such as smaller molecular size, opportunities for further structural modification thereby altering the physicochemical properties, cost-effectiveness, and convenient synthetic methodology. The present review highlights the recent evidence of chalcones as a privileged structure in AD drug development processes. Different classes of chalcone-derived analogs are summarized for the easy understanding of the previously reported analogs as well as the importance of certain functionalities in exhibiting cholinesterase inhibition. In this way, this review will shed light on the medicinal chemistry fraternity for the design and development of novel promising chalcone candidates for the treatment of AD.

Genetically modified animals for use in biopharmacology: from research to production

Introduction: In this review, the analysis of technologies for obtaining biologically active proteins from various sources is carried out, and the comparative analysis of technologies for creating producers of biologically active proteins is presented. Special attention is paid to genetically modified animals as bioreactors for the pharmaceutical industry of a new type. The necessity of improving the technology of development transgenic rabbit producers and creating a platform solution for the production of biological products is substantiated.

The advantages of using TrB for the production of recombinant proteins: The main advantages of using TrB are the low cost of obtaining valuable complex therapeutic human proteins in readily accessible fluids, their greater safety relative to proteins isolated directly from human blood, and the greater safety of the activity of the native protein.

The advantages of the mammary gland as a system for the expression of recombinant proteins: The mammary gland is the organ of choice for the expression of valuable recombinant proteins because milk is easy to collect in large volumes.

Methods for obtaining transgenic animals: The modern understanding of the regulation of gene expression and the discovery of new tools for gene editing can increase the efficiency of creating bioreactors for animals and help to obtain high concentrations of the target protein.

The advantages of using rabbits as bioreactors producing recombinant proteins in milk: The rabbit is a relatively small animal with a short duration of gestation, puberty and optimal size, capable of producing up to 5 liters of milk per year per female, receiving up to 300 grams of the target protein.

Studies on the cholinesterases inhibiting compounds from the Cassiopea andromeda venom

Cholinesterase inhibitors find application in the combat and care of several diseases, especially AD. Jellyfish venoms are the most promising sources of potent cholinesterase inhibitors. Therefore, it is of interest to study cholinesterases inhibiting compounds from the Cassiopea andromeda venom. We report bioactive compounds using the GC-MC method followed by molecular modeling and docking data analysis. The GC-MS analysis of the crude venom led to the identification of seven bioactive compounds (C1-C7), comprising the steroidal alkaloids, phenolic and carotenoid derivatives. The venom exhibited inhibitory activities against the cholinesterase enzymes. The compound C2, a Dioxolane steroid, displayed the strongest inhibition on both AChE and BChE activities for further consideration.

Molecular Recognition of Nerve Agents and Their Organophosphorus Surrogates: Toward Supramolecular Scavengers and Catalysts

Nerve agents are tetrahedral organophosphorus compounds (OPs) that were developed in the last century to irreversibly inhibit acetylcholinesterase (AChE) and therefore impede neurological signaling in living organisms. Exposure to OPs leads to a rapid development of symptoms from excessive salivation, nasal congestion and chest pain to convulsion and asphyxiation which if left untreated may lead to death. These potent toxins are prepared on a large scale from inexpensive staring materials, making it feasible for terrorist groups or states to use them against military and civilians. The existing antidotes provide limited protection and are difficult to apply to a large number of affected individuals. While new prophylactics are currently being developed, there is still need for therapeutics capable of both preventing and reversing the effects of OP poisoning. In this review, we describe how the science of molecular recognition can expand the pallet of tools for rapid and safe sequestration of nerve agents.

Immobilization of transgenic plant cells towards bioprinting for production of a recombinant biodefense agent

Transgenic rice cells (Oryza sativa) producing recombinant butyrylcholinesterase (BChE) as a prophylactic/therapeutic against organophosphate nerve agent poisoning, cocaine toxicity, and neurodegenerative diseases like Alzheimer's were immobilized in a polyethylene glycol-based hydrogel. The cells were sustained for 14 days in the semi-solid matrix, undergoing a growth phase from days 0-6, a BChE production phase in sugar-free medium from days 6-12, and a growth/recovery phase from days 12-14. Throughout this period, the cells maintained similar viability to those in suspension cultures and displayed analogous sugar consumption trends. The rice cells in the hydrogel also produced a significant amount of active BChE, comparable to the levels produced in liquid cultures. A considerable fraction of this BChE was secreted into the media, allowing for easier product separation. To the best of our knowledge, this proof-of-concept is the first report of immobilization of recombinant plant cells for continuous production of high-value heterologous proteins. This work serves as a foundation for further investigation towards plant cell bioprinting and the development of a simple, efficient, robust, modular, and potentially field-deployable bioreactor system for the manufacture of biologics. GRAPHICAL ABSTRACT AND LAY SUMMARY: Transgenic rice cells were combined with a polyethylene glycol tetra-acrylate (PEGTA) and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) bioink and cured with UV light to construct an immobilized cell-based protein production system. The cells were maintained for 14 days in the hydrogel matrix and were induced to actively make and secrete recombinant butyrylcholinesterase, a complex enzyme that irreversibly binds to and can hydrolyze organophosphate. This proof-of-concept study showcases the use of immobilized and potentially bioprintable plant cells to produce high-value proteins with prophylactic and therapeutic applications.

A Thermophilic Bacterial Esterase for Scavenging Nerve Agents: A Kinetic, Biophysical and Structural Study

Organophosphorous nerve agents (OPNA) pose an actual and major threat for both military and civilians alike, as an upsurge in their use has been observed in the recent years. Currently available treatments mitigate the effect of the nerve agents, and could be vastly improved by means of scavengers of the nerve agents. Consequently, efforts have been made over the years into investigating enzymes, also known as bioscavengers, which have the potential either to trap or hydrolyze these toxic compounds. We investigated the previously described esterase 2 from Thermogutta terrifontis (TtEst2) as a potential bioscavenger of nerve agents. As such, we assessed its potential against G-agents (tabun, sarin, and cyclosarin), VX, as well as the pesticide paraoxon. We report that TtEst2 is a good bioscavenger of paraoxon and G-agents, but is rather slow at scavenging VX. X-ray crystallography studies showed that TtEst2 forms an irreversible complex with the aforementioned agents, and allowed the identification of amino-acids, whose mutagenesis could lead to better scavenging properties for VX. In conjunction with its cheap production and purification processes, as well as a robust structural backbone, further engineering of TtEst2 could lead to a stopgap bioscavenger useful for in corpo scavenging or skin decontamination.

Nanomaterial-Enabled Sensors and Therapeutic Platforms for Reactive Organophosphates

Unintended exposure to harmful reactive organophosphates (OP), which comprise a group of nerve agents and agricultural pesticides, continues to pose a serious threat to human health and ecosystems due to their toxicity and prolonged stability. This underscores an unmet need for developing technologies that will allow sensitive OP detection, rapid decontamination and effective treatment of OP intoxication. Here, this article aims to review the status and prospect of emerging nanotechnologies and multifunctional nanomaterials that have shown considerable potential in advancing detection methods and treatment modalities. It begins with a brief introduction to OP types and their biochemical basis of toxicity followed by nanomaterial applications in two topical areas of primary interest. One topic relates to nanomaterial-based sensors which are applicable for OP detection and quantitative analysis by electrochemical, fluorescent, luminescent and spectrophotometric methods. The other topic is directed on nanotherapeutic platforms developed as OP remedies, which comprise nanocarriers for antidote drug delivery and nanoscavengers for OP inactivation and decontamination. In summary, this article addresses OP-responsive nanomaterials, their design concepts and growing impact on advancing our capability in the development of OP sensors, decontaminants and therapies.

Counteracting poisoning with chemical warfare nerve agents

Phosphylation of the pivotal enzyme acetylcholinesterase (AChE) by nerve agents (NAs) leads to irreversible inhibition of the enzyme and accumulation of neurotransmitter acetylcholine, which induces cholinergic crisis, that is, overstimulation of muscarinic and nicotinic membrane receptors in the central and peripheral nervous system. In severe cases, subsequent desensitisation of the receptors results in hypoxia, vasodepression, and respiratory arrest, followed by death. Prompt action is therefore critical to improve the chances of victim's survival and recovery. Standard therapy of NA poisoning generally involves administration of anticholinergic atropine and an oxime reactivator of phosphylated AChE. Anticholinesterase compounds or NA bioscavengers can also be applied to preserve native AChE from inhibition. With this review of 70 years of research we aim to present current and potential approaches to counteracting NA poisoning.

Cryo-electron microscopy of cholinesterases, present and future

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) exist in a variety of oligomeric forms, each with defined cellular and subcellular distributions. Although crystal structures of AChE and BChE have been available for many years, structures of the physiologically relevant ChE tetramer were only recently solved by cryo‐electron microscopy (cryo‐EM) single‐particle analysis. Here, we briefly review how these structures contribute to our understanding of cholinesterase oligomerization, highlighting the advantages of using cryo‐EM to resolve structures of protein assemblies that cannot be expressed recombinantly. We argue that the next frontier in cholinesterase structural biology is to image membrane‐anchored ChE oligomers directly in their native environment—the cell.

Structure and therapeutic uses of butyrylcholinesterase: Application in detoxification, Alzheimer's disease, and fat metabolism

Structural information of butyrylcholinesterase (BChE) and its variants associated with several diseases are discussed here. Pure human BChE has been proved safe and effective in treating organophosphorus (OPs) poisoning and has completed Phase 1 and 2 pharmacokinetic (PK) and safety studies. The introduction of specific mutations into native BChE to endow it a self-reactivating property has gained much progress in producing effective OPs hydrolases. The hydrolysis ability of native BChE on cocaine has been confirmed but was blocked to clinical application due to poor PK properties. Several BChE mutants with elevated cocaine hydrolysis activity were published, some of which have shown safety and efficiency in treating cocaine addiction of human. The increased level of BChE in progressed Alzheimer's disease patients made it a promising target to elevate acetylcholine level and attenuate cognitive status. A variety of selective BChE inhibitors with high inhibitory activity published in recent years are reviewed here. BChE could influence the weight and insulin secretion and resistance of BChE knockout (KO) mice through hydrolyzing ghrelin. The BChE-ghrelin pathway could also regulate aggressive behaviors of BChE-KO mice.

Effects of Kifunensine on Production and N-Glycosylation Modification of Butyrylcholinesterase in a Transgenic Rice Cell Culture Bioreactor

The production and N-glycosylation of recombinant human butyrylcholinesterase (BChE), a model highly glycosylated therapeutic protein, in a transgenic rice cell suspension culture treated with kifunensine, a strong α-mannosidase I inhibitor, was studied in a 5 L bioreactor. A media exchange was performed at day 7 of cultivation by removing spent sugar-rich medium (NB+S) and adding fresh sugar-free (NB-S) medium to induce the rice α-amylase 3D (RAmy3D) promoter to produce rice recombinant human BChE (rrBChE). Using a 1.25X-concentrated sugar-free medium together with an 80% reduced working volume during the media exchange led to a total active rrBChE production level of 79 ± 2 µg (g FW)^-1 or 7.5 ± 0.4 mg L^-1 in the presence of kifunensine, which was 1.5-times higher than our previous bioreactor runs using normal sugar-free (NB-S) media with no kifunensine treatment. Importantly, the amount of secreted active rrBChE in culture medium was enhanced in the presence of kifunensine, comprising 44% of the total active rrBChE at day 5 following induction. Coomassie-stained SDS-PAGE gel and Western blot analyses revealed different electrophoretic migration of purified rrBChE bands with and without kifunensine treatment, which was attributed to different N-glycoforms. N-Glycosylation analysis showed substantially increased oligomannose glycans (Man5/6/7/8) in rrBChE treated with kifunensine compared to controls. However, the mass-transfer limitation of kifunensine was likely the major reason for incomplete inhibition of α-mannosidase I in this bioreactor study.

Enhancing the Butyrylcholinesterase Activity in HEK-293 Cell Line by Dual-Promoter Vector Decorated on Lipofectamine

Purpose

Human butyrylcholinesterase (BChE) serves as a bio scavenger to counteract organophosphate poisoning. It is also a potential drug candidate in several therapeutic fields. Therefore, in the present study, we constructed a new dual-promoter plasmid consisting of Cytomegalovirus (CMV) and human elongation factor 1α (EF-1α) promoters and transfected that into HEK-293 cells using Lipofectamine to enhance the BChE secretion.

Methods

The new dual-promoter construction (pBudCE dual BChE) including two copies of the BChE gene was designed and transfected into cells by liposomal structures. The cloned plasmids were evaluated by enzyme digestion and gel electrophoresis analysis. Experimental groups were categorized into the cells transfected by pBudCE dual BChE (treatment), pCMV (positive control) vectors, and nontransfected cells (negative control). BChE gene expression was evaluated by qRT-PCR and the enzyme activity was assessed using modified Ellman’s method. The freeze-thaw process was carried out for analyzing the stability of the pBudCE dual BChE vector.

Results

Validation examination of the cloned plasmids confirmed the successful cloning process. The gene expression level and Ellman’s method value in pBudCE dual BChE was higher than the other groups. CMV promoter has also increased the enzyme activity, although the difference was not significant compared with the control group. Interestingly, freeze-thaw cycles followed by several passages did not affect the enzyme activity.

Conclusion

The designed construction with CMV and EF-1α promoters could increase BChE gene expression and the activity of the BChE enzyme in HEK-293 cell line. Large-scale production of BChE enzyme can be achieved by using dual-promoter plasmid construction compared to a single-promoter vector to be used in clinical trials.

Acetylcholinesterase inhibition resulting from exposure to inhaled OP can be prevented by pretreatment with BChE in both macaques and minipigs

More frequent and widespread nerve agent attacks highlight the need for efficacious pre- and post-exposure organophosphate (OP) counter-measures to protect military and civilian populations. Because of critical targeting of acetylcholinesterase (AChE) in the CNS by OPs, a pre-treatment candidate for preventing/reducing poisoning will be a broadly acting molecule that scavenges OPs in blood before they reach their physiological targets. Prophylactic human butyrylcholinesterase (HuBChE), the leading pretreatment candidate, has been shown to protect against multiple LD50's of nerve agents in rodents, macaques, and minipigs. This review describes the development of a HuBChE bioscavenger pretreatment from early proof-of-concept studies to pre-clinical studies with the native injectable enzyme and the development of aerosolized forms of recombinant enzyme, which can be delivered by inhalation nebulizer devices, to effect protection against inhaled OP nerve agents and insecticides. Early animal studies utilized parenteral exposure. However, lungs are the portal of entry for most volatile OP vapors and represent the major means of OP intoxication. In this regard, pretreat-ment with 7.5 mg/kg of HuBChE by IM injection protected minipigs against lethal sarin vapor and prevented AChE inhibition in the blood. This is similar to the five-day protection in macaques by an aerosolized rHuBChE using a nebulizer against aerosolized paraoxon (estimated to be an 8 mg/kg estimated human dose). Importantly, lethal inhaled doses of OP may be smaller relative to the same dose delivered by injection, thus reducing the protective HuBChE dose, while a combination of HuBChE and post-exposure oxime may prolong protection.

Proline 285 is integral for the reactivation of organophosphate-inhibited human butyrylcholinesterase by 2-PAM

Human butyrylcholinesterase (HuBChE) is a stoichiometric bioscavenger that protects from the toxicity of nerve agents. Non-human primates are suitable models for toxicity studies that cannot be performed in humans. We evaluated the biochemical properties of native macaque (MaBChE) tetramers, compared to recombinant MaBChE monomers, PEGylated recombinant MaBChE tetramers and monomers, and native HuBChE tetramers. K_m and k_cat values for butyrylthiocholine were independent of subunit assembly status. The K_m for all forms of MaBChE was about 70 μM, compared to 13 μM for HuBChE. The k_cat was about 100,000 min^-1 for MaBChE and 30,000 min^-1 for HuBChE. The reversible inhibitor ethopropazine had similar K_i values of 0.05 μM for all MaBChE forms and HuBChE. The bimolecular rate constant, ki, for inhibition by diisopropylfluorophosphate (DFP), an analog of sarin, was 2.2 to 2.5 × 10⁷ M^-1 min^-1 for all MaBChE forms and for HuBChE. A major difference between MaBChE and HuBChE was the rate of reactivation by 2-PAM. The second order rate constant for reactivation of DFP-inhibited MaBChE by 2-PAM was 1.4 M^-1 min^-1, but was 380 fold faster for DFP-inhibited HuBChE (k_r 531 M^-1 min^-1). The acyl pocket of MaBChE has Leu285 in place of Pro285 in HuBChE. The reactivation rate of DFP-inhibited HuBChE mutant P285L by 2-PAM was reduced 5.8-fold (k_r 92 M^-1 min^-1) indicating that P285 determines whether 2-PAM binds in an orientation that favors release of diisopropylphosphate. DFP-inhibited MaBChE treated with 0.2 M 2-PAM recovered 10% of its original activity, whereas DFP-inhibited HuBChE recovered 80% activity. It was concluded that the biochemical properties of MaBChE are similar to those of HuBChE except for the reactivation of DFP-inhibited BChE.

Three-dimensional brain-on-chip model using human iPSC-derived GABAergic neurons and astrocytes: Butyrylcholinesterase post-treatment for acute malathion exposure

Organophosphates (OPs) induce acute and chronic neurotoxicity, primarily by inhibiting acetylcholinesterase (AChE) activity as well as by necrosis, and apoptosis. Butyrylcholinesterase (BuChE), an exogenous bioscavenger of OPs, can be used as a treatment for OP exposure. It is prerequisite to develop in vitro brain models that can study BuChE post-treatment for acute OP exposure. In this study, we developed a three-dimensional (3D) brain-on-chip platform with human induced pluripotent stem cell (iPSC)-derived neurons and astrocytes to simulate human brain behavior. The platform consists of two compartments: 1) a hydrogel embedded with human iPSC-derived GABAergic neurons and astrocytes and 2) a perfusion channel with dynamic medium flow. The brain tissue constructs were exposed to Malathion (MT) at various concentrations and then treated with BuChE after 20 minutes of MT exposure. Results show that the iPSC-derived neurons and astrocytes directly interacted and formed synapses in the 3D matrix, and that treatment with BuChE improved viability after MT exposure up to a concentration of 10⁻³ M. We conclude that the 3D brain-on-chip platform with human iPSC-derived brain cells is a suitable model to study the neurotoxicity of OP exposure and evaluate therapeutic compounds for treatment.

Assessment of microchimerism following somatic cell nuclear transfer and natural pregnancies in goats

Microchimerism is defined as the presence of a small population of cells or DNA in 1 organism originated from a genetically different organism. It is well established that this phenomenon occurs in humans and mice as cells are exchanged between mother and fetus during gestation. Currently, no information is available about the presence of maternal microchimerism in goats, and the only published study is limited to an evaluation of fetal and fetal-fetal microchimerism in blood samples following natural breeding. In order to determine whether bidirectional fetal-maternal cell or DNA trafficking occurs in goats, we assessed: 1) fetal microchimerism in surrogates that gave birth to somatic cell nuclear transfer (SCNT)-derived transgenic offspring (n = 4), 2) maternal microchimerism following natural breeding of SCNT-derived transgenic does with a nontransgenic buck (n = 4), and 3) fetal-fetal microchimerism in nontransgenic twins of transgenic offspring (n = 3). Neomycin-resistance gene (NEO) gene was selected as the marker to detect the presence of the αMHC-TGF-β1-Neo transgene in kidney, liver, lung, lymph node, and spleen. We found no detectable maternal or fetal-fetal microchimerism in the investigated tissues of nontransgenic offspring. However, fetal microchimerism was detected in lymph node tissue of one of the surrogate dams carrying a SCNT pregnancy. These results indicate occurrence of cell trafficking from fetus to mother during SCNT pregnancies. The findings of this study have direct implications on the use and disposal of nontransgenic surrogates and nontransgenic offspring.

Adeno-associated virus-mediated expression of human butyrylcholinesterase to treat organophosphate poisoning

Rare diseases defined by genetic mutations are classic targets for gene therapy. More recently, researchers expanded the use of gene therapy in non-clinical studies to infectious diseases through the delivery of vectorized antibodies to well-defined antigens. Here, we further extend the utility of gene therapy beyond the “accepted” indications to include organophosphate poisoning. There are no approved preventives for the multi-organ damage resulting from acute or chronic exposure to organophosphates. We show that a single intramuscular injection of adeno-associated virus vector produces peak expression (~0.5 mg/ml) of active human butyrylcholinesterase (hBChE) in mice serum within 3–4 weeks post-treatment. This expression is sustained for up to 140 days post-injection with no silencing. Sustained expression of hBChE provided dose-dependent protection against VX in male and female mice despite detectable antibodies to hBChE in some mice, thereby demonstrating that expression of hBChE in vivo in mouse muscle is an effective prophylactic against organophosphate poisoning.

Increased pregnancy losses following serial somatic cell nuclear transfer in goats

Serial cloning by somatic cell nuclear transfer (SCNT) is a critical tool for the expansion of precious transgenic lines or resetting the lifespan of primary transgenic cells for multiple genetic modifications. We successfully produced second-generation cloned goats using donor neonatal fibroblasts from first-generation clones. However, our attempts to produce any third-generation clones failed. SCNT efficiency decreased progressively with the clonal generations. The rate of pregnancy loss was significantly greater in recloning groups (P<0.05). While no pregnancy loss was observed during the first round of SCNT, 14 out of 21 pregnancies aborted in the second round of SCNT and all pregnancies aborted in the third round of SCNT. In this retrospective study, we also investigated the expression of 21 developmentally important genes in muscle tissue of cloned (G1) and recloned (G2) offspring. The expression of most of these genes in live clones was found to be largely comparable to naturally reproduced control goats, but fibroblast growth factor 10 (FGF10), methyl CpG binding protein 2 (MECP2) and growth factor receptor bound protein 10 (GRB10) were differentially expressed (P<0.05) in G2 goats compared with G1 and controls. To study the effects of serial cloning on DNA methylation, the methylation pattern of differentially methylated regions in imprinted genes H19 and insulin like growth factor 2 receptor (IGF2R) were also analysed. Aberrant H19 DNA methylation patterns were detected in G1 and G2 clones.

Sheep and Goat Genome Engineering: From Random Transgenesis to the CRISPR Era

Sheep and goats are valuable livestock species that have been raised for their production of meat, milk, fiber, and other by-products. Due to their suitable size, short gestation period, and abundant secretion of milk, sheep and goats have become important model animals in agricultural, pharmaceutical, and biomedical research. Genome engineering has been widely applied to sheep and goat research. Pronuclear injection and somatic cell nuclear transfer represent the two primary procedures for the generation of genetically modified sheep and goats. Further assisted tools have emerged to enhance the efficiency of genetic modification and to simplify the generation of genetically modified founders. These tools include sperm-mediated gene transfer, viral vectors, RNA interference, recombinases, transposons, and endonucleases. Of these tools, the four classes of site-specific endonucleases (meganucleases, ZFNs, TALENs, and CRISPRs) have attracted wide attention due to their DNA double-strand break-inducing role, which enable desired DNA modifications based on the stimulation of native cellular DNA repair mechanisms. Currently, CRISPR systems dominate the field of genome editing. Gene-edited sheep and goats, generated using these tools, provide valuable models for investigations on gene functions, improving animal breeding, producing pharmaceuticals in milk, improving animal disease resistance, recapitulating human diseases, and providing hosts for the growth of human organs. In addition, more promising derivative tools of CRISPR systems have emerged such as base editors which enable the induction of single-base alterations without any requirements for homology-directed repair or DNA donor. These precise editors are helpful for revealing desirable phenotypes and correcting genetic diseases controlled by single bases. This review highlights the advances of genome engineering in sheep and goats over the past four decades with particular emphasis on the application of CRISPR/Cas9 systems.

Some Possibilities to Study New Prophylactics against Nerve Agents

Nerve agents belong to the most dangerous chemical warfare agents and can be/were misused by terrorists. Effective prophylaxis and treatment is necessary to diminish their effect. General principles of prophylaxis are summarized (protection against acetylcholinesterase inhibition, detoxification, treatment "in advance" and use of different drugs). They are based on the knowledge of mechanism of action of nerve agents. Among different examinations, it is necessary to test prophylactic effectivity in vivo and compare the results with protection in vitro. Chemical and biological approaches to the development of new prophylactics would be applied simultaneously during this research. Though the number of possible prophylactics is relatively high, the only four drugs were introduced into military medical practice. At present, pyridostigmine seems to be common prophylactic antidote; prophylactics panpal (tablets with pyridostigmine, trihexyphenidyl and benactyzine), transant (transdermal patch containing HI-6) are other means introduced into different armies as prophylactics. Scavenger commercionally available is Protexia®. Future development will be focused on scavengers, and on other drugs either reversible cholinesterase inhibitors (e.g., huperzine A, gallantamine, physostigmine, acridine derivatives) or other compounds.

Potential attenuation of early-life overfeeding-induced metabolic dysfunction by chronic maternal acetylcholinesterase inhibitor exposure

Evidence suggests that low concentration perinatal exposure to environmental contaminants, such as organophosphate (OP) is associated with later life insulin resistance and type 2 diabetes. The aim of this work was to investigate whether chronic maternal OP exposure exacerbates metabolic dysfunctions in early-overfed rats. During pregnancy and lactational periods, dams received OP by gavage. To induce neonatal overnutrition at postnatal day 3, pups were standardized to 9 or 3 per nest. At 90-days-old, glucose-insulin homeostasis and insulin release from pancreatic islets were analyzed. While both OP exposure and overfeeding alone did induce diabetogenic phenotypes in adulthood, there was no exacerbation in rats that experienced both. Unexpectedly, the group that experienced both had improved adiposity, metabolic parameters, attenuated insulin release from isolated islets in the presence of glucose and low function of muscarinic acetylcholine receptor M3, as well as an attenuation of beta cell mass hyperplasia. High levels of butyrylcholinesterase and low levels of insulin in milk may contribute to the OP-induced developmental programming. Our study showed that maternal OP exposure may program insulin release as well as endocrine pancreas structure, thus affecting metabolism in adulthood. Our data suggest that while perinatal OP exposure alone increases the risk for later life T2D, it actually reverses many of the programmed metabolic dysfunction that is induced by postnatal overfeeding. These surprising results may suggest that low-dose administration of acetylcholinesterase inhibitors could be of utility in preventing detrimental developmental programming that is caused by early-life overnutrition.

Synthesis and biological evaluation of 3-(4-aminophenyl)-coumarin derivatives as potential anti-Alzheimer's disease agents

The work is focused on the design of drugs that prevent and treat Alzheimer’s disease (AD) and its complications. A series of 3–(4-aminophenyl)-coumarin derivatives designed, synthesised, fully characterised and evaluated in vitro/vivo. The biological assay experiments showed that some compounds displayed a clearly selective inhibition for acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Among all compounds, compound 4m exhibited the highest AChE inhibition with an IC₅₀ value of 0.091 ± 0.011 µM and compound 4k exhibited the highest BuChE inhibition with an IC₅₀ value of 0.559 ± 0.017 µM. A zebrafish behaviour analyser (Zebrobox) was used to determine the behavioural effects of the active compound on the movement distance of the aluminium chloride-induced zebrafish. Compound 4m offered a potential drug design concept for the development of therapeutic or preventive agents for AD and its complications.

Aerosolized recombinant human butyrylcholinesterase delivered by a nebulizer provides long term protection against inhaled paraoxon in macaques

The recent intentional use of nerve agents and pesticides in Europe and Afghanistan highlights the need for an effective countermeasure against organophosphates (OP) toxins. The most developed pretreatment candidate to date is plasma (native) human butyrylcholinesterase (HuBChE), which is limited in availability and because of its 1:1 stoichiometry with OPs, a large dose will present challenges when delivered parenterally both in terms of pharmacokinetics and manageability in the field. A tetrameric recombinant (r) form of human BChE produced in CHO-K1 cells with similar structure, in vivo stability and antidotal efficacy as the native form, has been developed to deliver rHuBChE as an aerosol (aer) to form a pulmonary bioshield capable of neutralizing inhaled OPs in situ and prevent AChE inhibition in the blood and in the brain; the latter associated with the symptoms of OP toxicity. Previous proof-of-concept macaque studies demonstrated that delivery of 9 mg/kg using a microsprayer inserted down the trachea, resulted in protection against an inhaled dose of 15ug/kg of aer-paraoxon (aer-Px) given 72 h later. In the present studies, pulmonary delivery of rHuBChE in macaques was achieved using Aerogen vibrating mesh nebulizers, similar to that used for human self-administration. The promising findings indicate that despite the poor lung deposition observed in macaques using nebulizers (13-20%), protective levels of RBC-AChE were still present in the blood even when exposure aer-Px (55 μg/kg) was delayed for five days. This long term retention of 5 mg/kg rHuBChE deposited in the lung bodes well for the use of an aer-rHuBChE pretreatment in humans where a user-friendly customized nebulizer with increased lung deposition up to 50% will provide even longer protection at a lower dose.

Development of a long-acting Fc-fused cocaine hydrolase with improved yield of protein expression

Human butyrylcholinesterase (BChE) is known as a safe and effective protein for detoxification of organophosphorus (OP) nerve agents. Its rationally designed mutants with considerably improved catalytic activity against cocaine, known as cocaine hydrolases (CocHs), are recognized as the most promising drug candidates for the treatment of cocaine abuse. However, it is a grand challenge to efficiently produce active recombinant BChE and CocHs with a sufficiently long biological half-life. In the present study, starting from a promising CocH, known as CocH3 (i.e. A199S/F227A/S287G/A328W/Y332G mutant of human BChE), which has a ~2000-fold improved catalytic activity against cocaine compared to wild-type BChE, we designed an N-terminal fusion protein, Fc(M3)-(PAPAP)₂-CocH3, which was constructed by fusing Fc of human IgG1 to the N-terminal of CocH3 and further optimized by inserting a linker between the two protein domains. Without lowering the enzyme activity, Fc(M3)-(PAPAP)₂-CocH3 expressed in Chinese hamster ovary (CHO) cells has not only a long biological half-life of 105 ± 7 h in rats, but also a high yield of protein expression. Particularly, Fc(M3)-(PAPAP)₂-CocH3 has a ~21-fold increased protein expression yield in CHO cells compared to CocH3 under the same experimental conditions. Given the observations that Fc(M3)-(PAPAP)₂-CocH3 has not only a high catalytic activity against cocaine and a long biological half-life, but also a high yield of protein expression, this new protein entity reported in this study would be a more promising candidate for therapeutic treatment of cocaine overdose and addiction.

Resurrection and Reactivation of Acetylcholinesterase and Butyrylcholinesterase

Organophosphorus (OP) nerve agents and pesticides present significant threats to civilian and military populations. OP compounds include the nefarious G and V chemical nerve agents, but more commonly, civilians are exposed to less toxic OP pesticides, resulting in the same negative toxicological effects and thousands of deaths on an annual basis. After decades of research, no new therapeutics have been realized since the mid-1900s. Upon phosphylation of the catalytic serine residue, a process known as inhibition, there is an accumulation of acetylcholine (ACh) in the brain synapses and neuromuscular junctions, leading to a cholinergic crisis and eventually death. Oxime nucleophiles can reactivate select OP-inhibited acetylcholinesterase (AChE). Yet, the fields of reactivation of AChE and butyrylcholinesterase encounter additional challenges as broad-spectrum reactivation of either enzyme is difficult. Additional problems include the ability to cross the blood brain barrier (BBB) and to provide therapy in the central nervous system. Yet another complication arises in a competitive reaction, known as aging, whereby OP-inhibited AChE is converted to an inactive form, which until very recently, had been impossible to reverse to an active, functional form. Evaluations of uncharged oximes and other neutral nucleophiles have been made. Non-oxime reactivators, such as aromatic general bases and Mannich bases, have been developed. The issue of aging, which generates an anionic phosphylated serine residue, has been historically recalcitrant to recovery by any therapeutic approach-that is, until earlier this year. Mannich bases not only serve as reactivators of OP-inhibited AChE, but this class of compounds can also recover activity from the aged form of AChE, a process referred to as resurrection. This review covers the modern efforts to address all of these issues and notes the complexities of therapeutic development along these different lines of research.

Human umbilical cord perivascular cells: A novel source of the organophosphate antidote butyrylcholinesterase

Human butyrylcholinesterase (BChE) is a well-characterized bioscavenger with significant potential as a prophylactic or post-exposure treatment for organophosphate poisoning. Despite substantial efforts, BChE has proven technically challenging to produce in recombinant systems. Recombinant BChE tends to be insufficiently or incorrectly glycosylated, and consequently exhibits a truncated half-life, compromised activity, or is immunogenic. Thus, expired human plasma remains the only reliable source of the benchmark BChE tetramer, but production is costly and time intensive and presents possible blood-borne disease hazards. Here we report a human BChE production platform that produces functionally active, tetrameric BChE enzyme, without the addition of external factors such as polyproline peptides or chemical or gene modification required by other systems. Human umbilical cord perivascular cells (HUCPVCs) are a rich population of mesenchymal stromal cells (MSCs) derived from Wharton's jelly. We show that HUCPVCs naturally and stably secrete BChE during culture in xeno- and serum-free media, and can be gene-modified to increase BChE output. However, BChE secretion from HUCPVCs is limited by innate feedback mechanisms that can be interrupted by addition of miR 186 oligonucleotide mimics or by competitive inhibition of muscarinic cholinergic signalling receptors by addition of atropine. By contrast, adult bone marrow-derived mesenchymal stromal cells neither secrete measurable levels of BChE naturally, nor after gene modification. Further work is required to fully characterize and disable the intrinsic ceiling of HUCPVC-mediated BChE secretion to achieve commercially relevant enzyme output. However, HUCPVCs present a unique opportunity to produce both native and strategically engineered recombinant BChE enzyme in a human platform with the innate capacity to secrete the benchmark human plasma form.

Cryo-EM structure of the native butyrylcholinesterase tetramer reveals a dimer of dimers stabilized by a superhelical assembly

The quaternary structures of the cholinesterases, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), are essential for their localization and function. Of practical importance, BChE is a promising therapeutic candidate for intoxication by organophosphate nerve agents and insecticides, and for detoxification of addictive substances. Efficacy of the recombinant enzyme hinges on its having a long circulatory half-life; this, in turn, depends strongly on its ability to tetramerize. Here, we used cryoelectron microscopy (cryo-EM) to determine the structure of the highly glycosylated native BChE tetramer purified from human plasma at 5.7 Å. Our structure reveals that the BChE tetramer is organized as a staggered dimer of dimers. Tetramerization is mediated by assembly of the C-terminal tryptophan amphiphilic tetramerization (WAT) helices from each subunit as a superhelical assembly around a central lamellipodin-derived oligopeptide with a proline-rich attachment domain (PRAD) sequence that adopts a polyproline II helical conformation and runs antiparallel. The catalytic domains within a dimer are asymmetrically linked to the WAT/PRAD. In the resulting arrangement, the tetramerization domain is largely shielded by the catalytic domains, which may contribute to the stability of the human BChE (HuBChE) tetramer. Our cryo-EM structure reveals the basis for assembly of the native tetramers and has implications for the therapeutic applications of HuBChE. This mode of tetramerization is seen only in the cholinesterases but may provide a promising template for designing other proteins with improved circulatory residence times.

The insight of in vitro and in silico studies on cholinesterase inhibitors from the roots of Cimicifuga dahurica (Turcz.) Maxim

Cholinesterases (ChEs) are enzymes that break down neurotransmitters associated with cognitive function and memory. We isolated cinnamic acids (1 and 2), indolinones (3 and 4), and cycloartane triterpenoid derivatives (5-19) from the roots of Cimicifuga dahurica (Turcz.) Maxim. by chromatography. These compounds were evaluated for their inhibitory activity toward ChEs. Compound 1 was determined to have an IC50 value of 16.7 ± 1.9 μM, and to act as a competitive inhibitor of acetylcholinesterase (AChE). Compounds 3, 4 and 14 were found to be noncompetitive with IC50 values of 13.8 ± 1.5 and 6.5 ± 2.5 μM, and competitive with an IC50 value of 22.6 ± 0.4 μM, respectively, against butyrylcholinesterase (BuChE). Our molecular simulation suggested each key amino acid, Tyr337 of AChE and Asn228 of BuChE, which were corresponded with potential inhibitors 1, and 3 and 4, respectively. Compounds 1 and 4 were revealed to be promising compounds for inhibition of AChEs and BuChEs, respectively.

Purification of recombinant human butyrylcholinesterase on Hupresin®

Affinity chromatography on procainamide-Sepharose has been an important step in the purification of butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) since its introduction in 1978. The procainamide affinity gel has limitations. In the present report a new affinity gel called Hupresin® was evaluated for its ability to purify truncated, recombinant human butyrylcholinesterase (rHuBChE) expressed in a stably transfected Chinese Hamster Ovary cell line. We present a detailed example of the purification of rHuBChE secreted into 3940 mL of serum-free culture medium. The starting material contained 13,163 units of BChE activity (20.9 mg). rHuBChE was purified to homogeneity in a single step by passage over 82 mL of Hupresin® eluted with 0.1 M tetramethylammonium bromide in 20 mM TrisCl pH 7.5. The fraction with the highest specific activity of 630 units/mg contained 11 mg of BChE. Hupresin® is superior to procainamide-Sepharose for purification of BChE, but is not suitable for purifying native AChE because Hupresin® binds AChE so tightly that AChE is not released with buffers, but is desorbed with denaturing solvents such as 50% acetonitrile or 1% trifluoroacetic acid. Procainamide-Sepharose will continue to be useful for purification of AChE.

Identification of novel acetylcholinesterase inhibitors designed by pharmacophore-based virtual screening, molecular docking and bioassay

In this study, pharmacophore based 3D QSAR models for human acetylcholinesterase (AChE) inhibitors were generated, with good significance, statistical values (r2training = 0.73) and predictability (q2training = 0.67). It was further validated by three methods (Fischer's test, decoy set and Güner-Henry scoring method) to show that the models can be used to predict the biological activities of compounds without costly and time-consuming synthesis. The criteria for virtual screening were also validated by testing the selective AChE inhibitors. Virtual screening experiments and subsequent in vitro evaluation of promising hits revealed a novel and selective AChE inhibitor. Thus, the findings reported herein may provide a new strategy for the discovery of selective AChE inhibitors. The IC50 value of compounds 5c and 6a presented selective inhibition of AChE without inhibiting butyrylcholinesterase (BChE) at uM level. Molecular docking studies were performed to explain the potent AChE inhibition of the target compounds studies to explain high affinity.

Effects of AANAT overexpression on the inflammatory responses and autophagy activity in the cellular and transgenic animal levels

To explore the anti-inflammatory activity of endogenous produced melatonin, a melatonin-enriched animal model (goat) with AANAT transfer was successfully generated with somatic cell nuclear transfer (SCNT) technology. Basically, a pIRES2-EGFP-AANAT expression vector was constructed and was transferred into the female fetal fibroblast cells (FFCs) via electrotransfection and then the nuclear of the transgenic FFC was transferred to the eggs of the donor goats. The peripheral blood mononuclear cells (PBMCs) of the transgenic offspring expressed significantly higher levels of AANAT and melatonin synthetic function than those PBMCs from the wild-type (WT) animals. After challenge with lipopolysaccharide (LPS), the transgenic PBMCs had increased autophagosomes and LC3B expression while they exhibited suppressed production of the proinflammatory cytokines, IL1B and IL12 (IL12A-IL12B/p70), compared to their WT. The mechanistic analysis indicated that the anti-inflammatory activity of endogenous melatonin was mediated by MTNR1B (melatonin receptor 1B). MTNR1B stimulation activated the MAPK14 signaling pathway to promote cellular macroautophagy/autophagy, thus, suppressing the excessive inflammatory response of cellular. However, when the intact animals challenged with LPS, the serum proinflammatory cytokines were significantly higher in the transgenic goats than that in the WT. The results indicated that endogenous melatonin inhibited the MAPK1/3 signaling pathway and ROS production, subsequently downregulated gene expression of BECN1, ATG5 in PMBCs and then suppressed the autophagy activity of PBMCs and finally elevated levels of serum proinflammatory cytokines in transgenic animals, Herein we provided a novel melatonin-enriched animal model to study the potential effects of endogenously produced melatonin on inflammatory responses and autophagy activity.

Nerve Agents: What They Are, How They Work, How to Counter Them

Nerve agents are organophosphorus chemical warfare agents that exert their action through the irreversible inhibition of acetylcholinesterase, with a consequent overstimulation of cholinergic transmission followed by its shutdown. Beyond warfare, they have notoriously been employed in acts of terrorism as well as high profile assassinations. After a brief historical introduction on the development and deployment of nerve agents, this review provides a survey of their chemistry, the way they affect cholinergic transmission, the available treatment options, and the current directions for their improvement. As the review illustrates, despite their merits, the currently available treatment options present several shortcomings. Current research directions involve the search for improved antidotes, antagonists of the nicotinic receptors, small-molecule pretreatment options, as well as bioscavengers as macromolecular pretreatment options. These efforts are making good progress in many different directions and, hopefully, will lead to a lower target susceptibility, thus reducing the appeal of nerve agents as chemical weapons.

Development of Fc-Fused Cocaine Hydrolase for Cocaine Addiction Treatment: Catalytic and Pharmacokinetic Properties

Cocaine abuse is a worldwide public health and social problem without a US Food and Drug Administration (FDA)-approved medication. Accelerating cocaine metabolism that produces biologically inactive metabolites by administration of an efficient cocaine hydrolase (CocH) has been recognized as a promising strategy for cocaine abuse treatment. However, the therapeutic effects of CocH are limited by its short biological half-life (e.g., 8 h or shorter in rats). In this study, we designed and prepared a set of Fc-fusion proteins constructed by fusing Fc(M3) with CocH3 at the N-terminus of CocH3. A linker between the two protein domains was optimized to improve both the biological half-life and catalytic activity against cocaine. It has been concluded that Fc(M3)-G₆S-CocH3 not only has fully retained the catalytic efficiency of CocH3 against cocaine but also has the longest biological half-life (e.g., ∼ 136 h in rats) among all of the long-acting CocHs identified so far. A single dose (0.2 mg/kg, IV) of Fc(M3)-G₆S-CocH3 was able to significantly attenuate 15 mg/kg cocaine-induced hyperactivity for at least 11 days (268 h) after the Fc(M3)-G₆S-CocH3 administration.

Purification, characterization, and N-glycosylation of recombinant butyrylcholinesterase from transgenic rice cell suspension cultures

Recombinant butyrylcholinesterase produced in a metabolically regulated transgenic rice cell culture (rrBChE) was purified to produce a highly pure (95%), active form of enzyme. The developed downstream process uses common manufacturing friendly operations including tangential flow filtration, anion-exchange chromatography, and affinity chromatography to obtain a process recovery of 42% active rrBChE. The purified rrBChE was then characterized to confirm its comparability to the native human form of the molecule (hBChE). The recombinant and native enzyme demonstrated comparable enzymatic behavior and had an identical amino acid sequence. However, rrBChE differs in that it contains plant-type complex N-glycans, including an α-1,3 linked core fucose, and a β-1,2 xylose, and lacking a terminal sialic acid. Despite this difference, rrBChE is demonstrated to be an effective stoichiometric bioscavenger for five different organophosphorous nerve agents in vitro. Together, the efficient downstream processing scheme and functionality of rrBChE confirm its promise as a cost-effective alternative to hBChE for prophylactic and therapeutic use.

Delipidation of Plasma Has Minimal Effects on Human Butyrylcholinesterase

Human butyrylcholinesterase (BChE) is purified in large quantities from Cohn fraction IV-4 to use for protection against the toxicity of chemical warfare agents. Small scale preliminary experiments use outdated plasma from the American Red Cross as the starting material for purifying BChE (P06276). Many of the volunteer donor plasma samples are turbid with fat, the donor having eaten fatty food before the blood draw. The turbid fat interferes with enzyme assays performed in the spectrophotometer and with column chromatography. Our goal was to find a method to remove fat from plasma without loss of BChE activity. Satisfactory delipidation was achieved by adding a solution of 10% dextran sulfate and calcium chloride to fatty plasma, followed by centrifugation, and filtration through a 0.8 μm filter. Treatment with Aerosil also delipidated fatty plasma, but was accompanied by loss of 50% of the plasma volume. BChE activity and the BChE isozyme pattern on nondenaturing gel electrophoresis were unaffected by delipidation. BChE in delipidated plasma was efficiently captured by immobilized monoclonal antibodies B2 18-5 and mAb2. The immunopurified BChE was released from antibody binding with acid and visualized as a highly enriched, denatured BChE preparation by SDS gel electrophoresis. In conclusion, delipidation with dextran sulfate/CaCl2 preserves BChE activity and the tetramer structure of BChE.

Production of Recombinant Proteins in the Milk of Transgenic Animals: Current State and Prospects

The use of transgenic animals as bioreactors for the synthesis of the recombinant proteins secreted into milk is a current trend in the development of biotechnologies. Advances in genetic engineering, in particular the emergence of targeted genome editing technologies, have provided new opportunities and significantly improved efficiency in the generation of animals that produce recombinant proteins in milk, including economically important animals. Here, we present a retrospective review of technologies for generating transgenic animals, with emphasis on the creation of animals that produce recombinant proteins in milk. The current state and prospects for the development of this area of biotechnology are discussed in relation to the emergence of novel genome editing technologies. Experimental and practical techniques are briefly discussed.

Bacterial Expression of Human Butyrylcholinesterase as a Tool for Nerve Agent Bioscavengers Development

Human butyrylcholinesterase is a performant stoichiometric bioscavenger of organophosphorous nerve agents. It is either isolated from outdated plasma or functionally expressed in eukaryotic systems. Here, we report the production of active human butyrylcholinesterase in a prokaryotic system after optimization of the primary sequence through the Protein Repair One Stop Shop process, a structure- and sequence-based algorithm for soluble bacterial expression of difficult eukaryotic proteins. The mutant enzyme was purified to homogeneity. Its kinetic parameters with substrate are similar to the endogenous human butyrylcholinesterase or recombinants produced in eukaryotic systems. The isolated protein was prone to crystallize and its 2.5-Å X-ray structure revealed an active site gorge region identical to that of previously solved structures. The advantages of this alternate expression system, particularly for the generation of butyrylcholinesterase variants with nerve agent hydrolysis activity, are discussed.

Cholinesterase reactivators and bioscavengers for pre- and post-exposure treatments of organophosphorus poisoning

Organophosphorus agents (OPs) irreversibly inhibit acetylcholinesterase (AChE) causing a major cholinergic syndrome. The medical counter-measures of OP poisoning have not evolved for the last 30 years with carbamates for pretreatment, pyridinium oximes-based AChE reactivators, antimuscarinic drugs and neuroprotective benzodiazepines for post-exposure treatment. These drugs ensure protection of peripheral nervous system and mitigate acute effects of OP lethal doses. However, they have significant limitations. Pyridostigmine and oximes do not protect/reactivate central AChE. Oximes poorly reactivate AChE inhibited by phosphoramidates. In addition, current neuroprotectants do not protect the central nervous system shortly after the onset of seizures when brain damage becomes irreversible. New therapeutic approaches for pre- and post-exposure treatments involve detoxification of OP molecules before they reach their molecular targets by administrating catalytic bioscavengers, among them phosphotriesterases are the most promising. Novel generation of broad spectrum reactivators are designed for crossing the blood-brain barrier and reactivate central AChE. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.