UCLA

The high-fat low-carbohydrate ketogenic diet (KD) is an established dietary therapy for individuals with refractory epilepsy, whose seizures are resistant to existing anti-epileptic drugs. However, use of the KD to treat refractory epilepsy is challenging because the diet is difficult for patients to implement, manage, and maintain due to its severe restrictiveness and adverse side effects. Exactly how the clinical KD reduces seizure symptoms when other anti-epileptic drugs are ineffective is poorly understood. The gut microbiome has emerged as a key intermediary between diet and host metabolism, neural activity, and behavior. The gut microbiome modulates seizure susceptibility and the anti-seizure effects of the ketogenic diet (KD) in animal models. This dissertation work seeks to understand if these relationships seen in animal models translate to KD therapies for human drug-resistant epilepsy. Herein we report that KD therapy in children with pediatric epilepsy alters the function of the human gut microbiome. In addition, colonizing mice with KD-associated human gut microbes confers increased resistance to 6-Hz psychomotor seizures, as compared to colonization with gut microbes from matched pre-treatment controls. Parallel analysis of human donor and mouse recipient metagenomic and metabolomic profiles identifies subsets of shared functional features that are seen in response to KD treatment in humans and preserved upon transfer to mice fed a standard diet. These include enriched representation of microbial genes and metabolites related to anaplerosis, fatty acid beta-oxidation, and amino acid metabolism. Mice colonized with KD-associated human gut microbes further exhibit altered hippocampal and frontal cortical transcriptomic profiles relative to colonized pre-treatment controls, including differential expression of genes related to ATP synthesis, glutathione metabolism, oxidative phosphorylation, and translation. Integrative co-occurrence network analysis of the metagenomic, metabolomic, and brain transcriptomic datasets identifies features that are shared between human and mouse networks, and select microbial functional pathways and metabolites that are candidate primary drivers of hippocampal expression signatures related to epilepsy. Together, these findings reveal key microbial functions and biological pathways that are altered by clinical KD therapies for pediatric refractory epilepsy and further linked to microbiome-induced alterations in brain gene expression and seizure protection in mice.The high-fat low-carbohydrate ketogenic diet (KD) is an established dietary therapy for individuals with refractory epilepsy, whose seizures are resistant to existing anti-epileptic drugs. However, use of the KD to treat refractory epilepsy is challenging because the diet is difficult for patients to implement, manage, and maintain due to its severe restrictiveness and adverse side effects. Exactly how the clinical KD reduces seizure symptoms when other anti-epileptic drugs are ineffective is poorly understood. The gut microbiome has emerged as a key intermediary between diet and host metabolism, neural activity, and behavior. The gut microbiome modulates seizure susceptibility and the anti-seizure effects of the ketogenic diet (KD) in animal models. This dissertation work seeks to understand if these relationships seen in animal models translate to KD therapies for human drug-resistant epilepsy. Herein we report that KD therapy in children with pediatric epilepsy alters the function of the human gut microbiome. In addition, colonizing mice with KD-associated human gut microbes confers increased resistance to 6-Hz psychomotor seizures, as compared to colonization with gut microbes from matched pre-treatment controls. Parallel analysis of human donor and mouse recipient metagenomic and metabolomic profiles identifies subsets of shared functional features that are seen in response to KD treatment in humans and preserved upon transfer to mice fed a standard diet. These include enriched representation of microbial genes and metabolites related to anaplerosis, fatty acid beta-oxidation, and amino acid metabolism. Mice colonized with KD-associated human gut microbes further exhibit altered hippocampal and frontal cortical transcriptomic profiles relative to colonized pre-treatment controls, including differential expression of genes related to ATP synthesis, glutathione metabolism, oxidative phosphorylation, and translation. Integrative co-occurrence network analysis of the metagenomic, metabolomic, and brain transcriptomic datasets identifies features that are shared between human and mouse networks, and select microbial functional pathways and metabolites that are candidate primary drivers of hippocampal expression signatures related to epilepsy. Together, these findings reveal key microbial functions and biological pathways that are altered by clinical KD therapies for pediatric refractory epilepsy and further linked to microbiome-induced alterations in brain gene expression and seizure protection in mice.