Plasmalogen-Independent Neuroprotection: Synthetic alkyl ether lipids activate signaling to mitigate neuroinflammation and enhance cognitive function

Abstract

Neuroinflammation is a key driver of neurodegenerative disorders, with chronic activation of the NF-{kappa}B pathway contributing to neuronal dysfunction and disease progression. In this study, we report that KIT-8, a synthetic alkyl ether lipid, exerts potent anti-inflammatory and neuroprotective effects despite its inability to be converted into plasmalogens within cells unlike its analog KIT-13, which is known to generate plasmalogens. Remarkably, KIT-8 activates key intracellular signaling pathways, including phosphorylation of ERK and AKT, and enhances brain-derived neurotrophic factor (Bdnf) expression in Neuro2A cells, thereby mimicking the actions of both KIT-13 and natural plasmalogens. Furthermore, KIT-8 significantly improves memory function in mice, underscoring its inherent therapeutic potential. Importantly, the biological activity of KIT-8 suggests that plasmalogen synthesis is not required for its functional effects, introducing a novel concept in ether lipid biology. Supporting this notion, we identified additional alkyl ether lipid analogs, KIT-19 and KIT-20, which also demonstrated anti-inflammatory properties despite lacking the ability to generate plasmalogens. These findings indicate that the ether bond structure alone may be sufficient to confer biological activity. To explore this further, we designed and synthesized a series of structurally distinct alkyl ether lipids (KIT compounds) retaining an ether bond at the sn-2 position. In an LPS-induced inflammatory model using mouse-derived microglial MG6 cells, selected compounds KIT-8, KIT-19, and KIT-20 significantly suppressed NF-{kappa}B signaling, reduced p65 nuclear translocation, and downregulated the expression of pro-inflammatory mediators IL-1{beta} and NOS2. Given the cognitive benefits associated with plasmalogens in Alzheimers disease, our findings position alkyl ether lipids as promising standalone bioactive molecules, capable of mitigating neuroinflammation and enhancing neuronal function independently of plasmalogen synthesis.