The impact on the activity of acetylcholinesterase of a polylysine-ApoE peptide carrier targeting the blood brain barrier

Abstract

-The K16ApoE peptide has been demonstrated to deliver a supraphysiological level of protein therapeutics to the brain and further increase the life-span of mice with a lysosomal storage disorder (LSD). If successfully developed, K16ApoE would provide new treatments for LSD and many other neurological diseases. However, while the K16ApoE can cross the blood-brain barrier, data indicates a toxic response associated with it. The mechanism of toxicity must be resolved for further clinical translation. The toxic response towards the peptide was hypothesized to be induced by inhibition of acetylcholinesterase (AChE) activity at neuro-muscular junction. Here, the dose-response analysis between AChE and K16ApoE was conducted in both female and male mice. Results demonstrated that AChE activity was significantly reduced with increasing dose of K16ApoE except for the mid-dose where a dramatic increase in AChE activity was observed. Also, obvious difference in response to K16ApoE was shown when considering the influence from sex and body weight. Though the statistical analysis of the dose response and survival ratio suggested that AChE is not the primary mechanism of action for the acute toxicity of K16ApoE, the complex inhibition/stimulation response of AChE indicated that this enzyme must play a role in the toxicity of the peptide.

K16ApoE inhibits the activity of acetylcholinesterase but is not the primary toxicological mechanism in mice

“…AChE is mainly distributed in nervous tissue and muscles (Wilson, 2014). Previous research (Michelena et al, 2018) hypothesized that K16ApoE inhibits AChE activity in the neuro-muscular junction and further leads to muscle spasms and respiration failure. The diaphragm is directly associated with respiration, and the brain can regulate respiration.…”

“…The studies (Lu et al, 2018;Michelena et al, 2018) hypothesized that K16ApoE toxicity is induced by acetylcholinesterase (AChE) inhibition in the brain. From molecular docking, the authors found that K16ApoE…”

“…Detergent should be used to promote the release of AChE from membranes. However, no detergent was used in the traditional AChE assay (Ellman et al, 1961) in previous K16ApoE effect research (Lu et al, 2018;Michelena et al, 2018), which means the AChE was not released from the membranes. Therefore, we prepared a homogenization buffer containing 0.1% Triton X-100 to promote the release of AChE.…”

Designing peptide nanoparticles for efficient brain delivery

“…non-viral vector functionalised with a different ApoE-derived sequence (LRVRLASHLRKLRKRLLRDA) has been successfully used for the delivery of an array of both small drugs and proteins to the brain via intravenous (IV) injection [215][216][217][218]. However, the development of these P(Lys) 16 NPs has been hampered by a peptide dose-dependent toxicity associated to an unexpected inhibition of acetylcholinesterase, which still remains to be fully understood [219].…”

K16ApoE interrupts cerebral blood flow and induces blood cell aggregation in mice

“…A previous study (Michelena et al, 2018) speculated that the toxicity of K16ApoE was caused by an acute reduction of acetylcholinesterase (AChE) activity at the neuromuscular junction. However, our previous work (Shao and Michelena, 2023) found that K16ApoE could not reduce AChE activity at lethal doses in animal experiments.…”