Dimerization of human butyrylcholinesterase expressed in bacterium for development of a thermally stable bioscavenger of organophosphorus compounds

Fused human paraoxonase 1 as a prophylactic agent against organophosphate poisoning

Organophosphates (OPs) are highly neurotoxic compounds and certain OP-compounds are also exploited as a weapon of mass destruction and chemical warfare in terrorist attacks. Available prophylactic and post-exposure treatments are less effective and also have serious side-effects. Thus, there is a dire need to develop effective and safe prophylactic agent(s) against OP-poisoning. Human Paraoxonase 1 (hPON1) can hydrolyze a wide range of OP molecules and can be developed as an effective and safe prophylactic agent. Thus, there is a dire need in the art to develop variant(s) of rhPON1 that not only possess 'good' OP-hydrolyzing activity but also have improved pharmacokinetic properties. In this report, we describe the characterization of the fused hPON1 (FHP) variant that not only exhibit enhanced in vivo pharmacokinetic properties but also delay / prevent the symptoms of OP-poisoning and prevents OP-induced mortality in rats.

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.

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.