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## Overview Vagus nerve stimulation (VNS) is an established therapeutic platform for epilepsy and depression, with growing interest in inflammatory and autoimmune conditions via the 'inflammatory reflex.' A new research direction uses optogenetics to stimulate distinct axonal subpopulations within the vagus nerve with cell-type specificity previously unavailable. ## Selective Optogenetic VNS A silicone spiral nerve cuff with integrated microscale LEDs was fabricated and implanted on the left cervical vagus nerve of transgenic mice (biorxiv:2026.06.10.731452). The device enables selective stimulation of cholinergic (ChAT) or glutamatergic (Vglut2) axonal subpopulations via channelrhodopsin-2 (ChR2) expression under cell-type-specific promoters. This approach allows researchers to dissect which vagal motor subpopulations mediate anti-inflammatory effects. ## Endotoxemia Model Results In a lipopolysaccharide-induced endotoxemia model (3 mg/kg intraperitoneal), selective VNS of specific axonal subpopulations reportedly modulated systemic inflammatory cytokines. The study provides mechanistic evidence linking specific vagal motor populations to cytokine attenuation, potentially resolving long-standing ambiguity about which nerve fibers mediate therapeutic VNS effects. ## Therapeutic and Commercial Implications - **Bioelectronic medicine**: The inflammatory reflex as a therapeutic target for sepsis, rheumatoid arthritis, inflammatory bowel disease, and COVID-19-related cytokine storms has attracted significant investment (SetPoint Medical, Galvani Bioelectronics). - **Device specificity**: Current clinical VNS devices stimulate the entire nerve nonselectively; selective stimulation could reduce off-target side effects and improve therapeutic windows. - **IP landscape**: Nerve cuff designs with integrated light delivery and optogenetic selectivity approaches are likely patentable; prior art landscape is evolving rapidly. ## Regulatory Path Optogenetic approaches require viral vector delivery of ChR2, which faces a distinct FDA regulatory pathway compared to purely electrical VNS devices. Human translation requires addressing gene therapy regulatory requirements alongside device approvals.