A pH-sensitive closed-loop nanomachine to control hyperexcitability at the single neuron level

Area of Science:

• Neuroscience
• Biotechnology
• Genetics

Background:

• Epilepsy affects 1% of the population, with 30% of patients exhibiting drug resistance.
• Optogenetics offers an effective epilepsy treatment but faces challenges in deep brain illumination.
• Novel light sources are crucial for advancing optogenetic therapies for epilepsy.

Purpose of the Study:

• To develop a closed-loop chemo-optogenetic system for treating drug-refractory epilepsy.
• To create a pH-sensitive inhibitory luminopsin (pHIL) capable of silencing neuronal activity.
• To assess the efficacy of pHIL in preclinical epilepsy models.

Main Methods:

• Engineered a pHIL nanomachine integrating a luciferase, E2GFP pH sensor, and halorhodopsin actuator.
• Demonstrated pHIL's ability to sense intracellular pH drops and activate halorhodopsin via bioluminescence resonance energy transfer.
• Validated pHIL's efficacy in primary neurons and in vivo using pilocarpine-induced seizures and a genetic epilepsy mouse model.

Main Results:

• pHIL effectively silenced neuronal hyperactivity by optogenetically aborting paroxysmal activity in response to pH changes.
• In vivo administration of pHIL and coelenterazine reduced seizure duration and increased latency in pilocarpine-induced seizures.
• Significant reduction in seizure manifestations was observed in a genetic epilepsy mouse model without affecting higher brain functions.

Conclusions:

• pHIL functions as a closed-loop chemo-optogenetic system responsive to neuronal activity.
• pHIL demonstrates potential as a novel therapeutic strategy for drug-refractory epilepsy.
• This approach offers a promising alternative for epilepsy treatment, overcoming limitations of traditional optogenetics.