Funded Projects

The Role of Microglia in Prader-Willi Syndrome and a Hypothalamic Gene Therapy

Funding Summary

Recently, Dr. Cao validated the safety and efficacy of a novel brain-directed gene therapy (BDNF) for metabolic and behavioral deficits observed in a preclinical mouse model of PWS, and identified BDNF as a potential therapeutic target to treat metabolic and behavioral aspects of PWS. Follow-up studies by our group investigated the genetic profile of PWS-like mice and how the introduction of BDNF alters the expression of genes in the brain. Interestingly, PWS-like mice displayed a genetic profile showing inflammation and activation of the brain’s resident immune cells, microglia. Strikingly, BDNF gene therapy resulted in a reversal of the inflammatory phenotype, leading our group to wonder whether neuroinflammation and microglia might play a role in PWS. This study will assess whether microglia structure, function, and genetic profiles are altered within a PWS mouse model. Furthermore, this study will determine whether removal of microglia can prevent PWS-related metabolic dysfunction and if microglia modulation underlies the previously observed ability of BDNF gene therapy to address PWS symptoms. If successful, this work would be among the first to identify microglia as a new cellular population of interest in PWS and could eventually lead to development of new PWS therapeutic strategies targeting microglia and neuroinflammation.

Dr. Theresa Strong, Director of Research Programs, explains the details of this project in this video clip.

Lay Abstract

Here, we will perform a study to expand upon previous FPWR-funded work performed by our lab. Recently, we validated the safety and efficacy of a novel brain-directed gene therapy for metabolic and behavioral deficits observed in a preclinical mouse model of PWS. Brain-derived neurotrophic factor (BDNF) was chosen as a therapeutic target because it works downstream of aberrant signaling pathways in PWS and previous work has shown that the PWS-related genetic profile in the brain may result from reduced BDNF. Independent of this work, BDNF has been studied for decades and its ability to induce beneficial metabolic and behavioral outcomes—including reduced fat mass, increased energy expenditure, reduced food intake, increased physical activity, improved blood sugar control, alleviation of fatty liver, reduced anxiety-like behavior, and reduced depression-like behavior—is well known. Our proof-of-concept study was successful and indeed identified BDNF as a potential therapeutic target to treat metabolic and behavioral aspects of PWS.

Follow-up studies by our group investigated the genetic profile of PWS-like mice and how the introduction of BDNF alters the expression of genes in the brain. Interestingly, PWS-like mice displayed a genetic profile showing inflammation and activation of the brain’s resident immune cells, microglia. These preliminary results match data that are observed in humans with PWS. Strikingly, BDNF gene therapy resulted in a reversal of the inflammatory phenotype, leading our group to wonder whether neuroinflammation and microglia might play a role in PWS. This study will assess whether microglia structure, function, and genetic profiles are altered within a PWS mouse model. Furthermore, this study will determine whether removal of microglia can prevent PWS-related metabolic dysfunction and if microglia modulation underlies the previously observed ability of BDNF gene therapy to address PWS symptoms. If successful, this work would be among the first to identify microglia as a new cellular population of interest in PWS and could eventually lead to development of new PWS therapeutic strategies targeting microglia and neuroinflammation. Furthermore, this work may help researchers understand how BDNF works to induce therapeutic benefit.

Research Outcome

Prader-Willi syndrome (PWS) is a rare genetic disease characterized by developmental delays, intellectual impairment, excessive hunger, obesity and associated metabolic dysfunction, and various behavioral abnormalities. Standard care is limited to growth hormone therapy and strict supervision of food intake, highlighting urgent need for new therapeutic strategies. Our previous work revealed a proinflammatory transcriptomic profile in the hypothalamus of Magel2-null mouse model of PWS, recapitulating the hypothalamic inflammation and activation of microglia in individuals with PWS. In this study, microglia were depleted with a CSF1R inhibitor PLX5622. In middle-aged (9-10-months) female Magel2-null mice, PLX5622 resulted in significant amelioration of genotypic increase of food intake and significant improvement in glucose metabolism in Magel2-null mice while exerted no effect on glucose tolerance in wildtype counterparts. These metabolic improvements were associated with antiinflammation gene signature in the liver and reduced hepatic signaling pathways involved in gluconeogenesis and de novo lipogenesis in Magel2-null mice. However, PLX5622 exerted lesser metabolic effects in young adult (3-5-months) Magel2-null mice. These results suggest PLX5622 could ameliorate PWS-related metabolic abnormalities in an age-dependent manner warranting further investigation. This study is likely the first to test a new category of therapeutics for the PWS by an immune-modulatory drug and thereby relevant to future translating research. 

Funded Year:

2023

Awarded to:

Lei Cao, Ph.D.

Amount:

$161,990

Institution:

The Ohio State University

Researcher:

LeiCao