Researchers from the Mitochondrial Medicine Program at Children’s Hospital of Philadelphia (CHOP) developed a new zebrafish model using gene editing technology to enable detailed study of an inherited metabolic disease caused by dihydrolipoamide dehydrogenase (DLD) deficiency. Therapeutic modeling in these zebrafish has already helped researchers to identify potential therapeutic candidates for patients living with this complex mitochondrial disorder. The findings were recently published by the journal JCI Insight.
Dihydrolipoamide dehydrogenase (DLD) deficiency is a rare, autosomal recessive, nuclear gene-based mitochondrial disorder that disrupts several enzyme complexes needed to break down cellular nutrients. Like other mitochondrial disorders, DLD can affect multiple organs and systems in the body, from brain to muscle or liver. Current therapies for DLD deficiency are ineffective, highlighting the need for improved preclinical models to objectively evaluate potential treatments and enhance patient outcomes.
Zebrafish have revolutionized research into a wide variety of rare and complex genetic diseases. In early larval development stages, their transparent bodies allow researchers to more easily screen for disease impact across diverse tissues and organs. This allows for determination of organ-specific disease effects and which disease manifestations may be improved with specific therapies.
Building off a prior study describing the development of a preclinical invertebrate animal model in the roundworm C. elegans to study DLD deficiency, the researchers have now developed the first viable vertebrate animal model in Danio rerio, or zebrafish, that models the cause and key consequences of DLD deficiency.
The researchers found that the zebrafish model of DLD deficiency had shortened survival from more than two years to less than 10 days, an uninflated swim bladder that negatively impacts their buoyancy, and significantly reduced neuromuscular activity, among other symptoms. These models also displayed biochemical hallmarks of DLD deficiency, including increased pyruvate and lactate levels, a build-up of multiple amino acids in their tissues due to impairment of several enzyme complexes in which DLD functions, and enlarged mitochondria with very abnormal ultrastructure in multiple organs.
Importantly, the study found that treating the DLD deficient animals with probucol (an anti-hyperlipidemic drug) or thiamine (vitamin B1, a cofactor for DLD) improved larval swim activity, suggesting that both therapies could potentially be studied in future clinical trials. Similarly, the study showed that multiple proposed candidates showed no therapeutic benefit.
“This study builds upon our previous preclinical work in a substantial way, providing us with a very severely ill, preclinical vertebrate animal model for rapidly determining which precision therapeutic options are most worth exploring to help treat these patients with complex, multisystem diseases,” said Marni Falk, MD, Professor of Pediatrics and Executive Director of the Mitochondrial Medicine Program at CHOP and senior author of the study.
This study was supported by the Joshua Cohen DLD Research Fund, CHOP MMFP, Saol Therapeutics, Stealth BioTherapeutics, and the National Institutes of Health grant R35-GM134863.
Lavorato et al, “dldhcri3 zebrafish exhibited altered mitochondrial ultrastructure, morphology and dysfunction partially rescued by probucol or thiamine.” JCI Insight. Online August 20, 2024. DOI: 10.1172/jci.insight.178973.
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Researchers from the Mitochondrial Medicine Program at Children’s Hospital of Philadelphia (CHOP) developed a new zebrafish model using gene editing technology to enable detailed study of an inherited metabolic disease caused by dihydrolipoamide dehydrogenase (DLD) deficiency. Therapeutic modeling in these zebrafish has already helped researchers to identify potential therapeutic candidates for patients living with this complex mitochondrial disorder. The findings were recently published by the journal JCI Insight.
Dihydrolipoamide dehydrogenase (DLD) deficiency is a rare, autosomal recessive, nuclear gene-based mitochondrial disorder that disrupts several enzyme complexes needed to break down cellular nutrients. Like other mitochondrial disorders, DLD can affect multiple organs and systems in the body, from brain to muscle or liver. Current therapies for DLD deficiency are ineffective, highlighting the need for improved preclinical models to objectively evaluate potential treatments and enhance patient outcomes.
Zebrafish have revolutionized research into a wide variety of rare and complex genetic diseases. In early larval development stages, their transparent bodies allow researchers to more easily screen for disease impact across diverse tissues and organs. This allows for determination of organ-specific disease effects and which disease manifestations may be improved with specific therapies.
Building off a prior study describing the development of a preclinical invertebrate animal model in the roundworm C. elegans to study DLD deficiency, the researchers have now developed the first viable vertebrate animal model in Danio rerio, or zebrafish, that models the cause and key consequences of DLD deficiency.
The researchers found that the zebrafish model of DLD deficiency had shortened survival from more than two years to less than 10 days, an uninflated swim bladder that negatively impacts their buoyancy, and significantly reduced neuromuscular activity, among other symptoms. These models also displayed biochemical hallmarks of DLD deficiency, including increased pyruvate and lactate levels, a build-up of multiple amino acids in their tissues due to impairment of several enzyme complexes in which DLD functions, and enlarged mitochondria with very abnormal ultrastructure in multiple organs.
Importantly, the study found that treating the DLD deficient animals with probucol (an anti-hyperlipidemic drug) or thiamine (vitamin B1, a cofactor for DLD) improved larval swim activity, suggesting that both therapies could potentially be studied in future clinical trials. Similarly, the study showed that multiple proposed candidates showed no therapeutic benefit.
“This study builds upon our previous preclinical work in a substantial way, providing us with a very severely ill, preclinical vertebrate animal model for rapidly determining which precision therapeutic options are most worth exploring to help treat these patients with complex, multisystem diseases,” said Marni Falk, MD, Professor of Pediatrics and Executive Director of the Mitochondrial Medicine Program at CHOP and senior author of the study.
This study was supported by the Joshua Cohen DLD Research Fund, CHOP MMFP, Saol Therapeutics, Stealth BioTherapeutics, and the National Institutes of Health grant R35-GM134863.
Lavorato et al, “dldhcri3 zebrafish exhibited altered mitochondrial ultrastructure, morphology and dysfunction partially rescued by probucol or thiamine.” JCI Insight. Online August 20, 2024. DOI: 10.1172/jci.insight.178973.
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