Hashimoto-Torii Archives

Caspases may link brain cell degeneration and cardiac surgery

April 29, 2022

The review summarizes both the known physiological roles of caspases as well as some of the well-characterized neurotoxic effects of anesthetics in pre-clinical models.

A review article in the journal Cell Press: Trends in Neuroscience outlines the wide variety of cellular signaling roles for caspase proteins — a type of cellular enzyme best known for its documented role in the natural process of cell death (apoptosis). The authors, including Nemanja Saric, Ph.D., Kazue Hashimoto-Torii, Ph.D., and Nobuyuki Ishibashi, M.D., all from Children’s National Research Institute, pay particular attention to what the scientific literature shows about caspases’ non-apoptotic roles in the neurons specifically. They also highlight research showing how, when activated during a cardiac surgery with anesthesia and cardiopulmonary bypass, these enzymes may contribute to the degeneration of brain cells seen in young children who undergo heart surgery for critical congenital heart defects (CHDs).

Why it matters

The review summarizes both the known physiological roles of caspases as well as some of the well-characterized neurotoxic effects of anesthetics in pre-clinical models.

The authors propose that these non-apoptotic activities of caspases may be behind some of the adverse effects on the developing brain related to cardiac surgery and anesthesia. Those adverse effects are known to increase risk of behavioral impairments in children with congenital heart disease who underwent cardiac surgery with both anesthesia and cardiopulmonary bypass at a very young age.

This work is the first to propose a possible link between developmental anesthesia neurotoxicity and caspase-dependent cellular responses.

The patient benefit

Better understanding of the time and dose-dependent effects of general anesthetics on the developing brain, particularly in children who have genetic predispositions to conditions such as CHDs, will help researchers understand their role (if any) in behavioral problems often encountered by these patients after surgery.

If found to be a contributing factor, perhaps new therapies to mitigate this caspase activity might be explored to alleviate some of these adverse effects on the developing brain.

What’s next?

The authors hope to stimulate more in-depth research into caspase signaling events, particularly related to how these signaling events change when an anesthetic is introduced. Deeper understanding of how anesthetics impact caspase activation in the developing brain will allow for better assessments of the risk for children who need major surgery early in life.

Children’s National leads the way

Children’s National Hospital leads studies funded by the U.S. Department of Defense to better understand how these other roles of caspases, which until now have not been well-documented, may contribute to brain cell degeneration when activated by prolonged anesthesia and cardiopulmonary bypass during cardiac surgery for congenital heart disease.

Multidisciplinary team seeks to reverse epigenetic changes associated with fetal alcohol syndrome disorder

January 21, 2022

The team hopes to optimize and develop treatments that can reverse epigenetic changes in clinical trials, paving the way to make significant progress in the field — something that is lacking to date.

A clinical team joined forces with a research team at Children’s National Hospital to help advance treatments that can improve a child’s development caused by fetal alcohol syndrome disorder (FASDs), which is a group of conditions that can occur in a person who was exposed to alcohol before birth. This boost in collaboration between the bench and clinical hopes to optimize and develop treatments that can reverse epigenetic changes in clinical trials, paving the way to make significant progress in the field — something that is lacking to date.

So far, Children’s National experts have published various pre-clinical studies that identified epigenetic changes caused by alcohol exposure during pregnancy. These changes observed in the pre-clinical models created neuropsychiatric problems like patients with fetal alcohol syndrome disorder. Now, they want to bring such potential treatments effective in pre-clinical models to the bedside.

“As a first step, we are going to test whether the epigenetic changes that were observed in pre-clinical models of FASD are also true in human patients,” said Kazue Hashimoto-Torii, Ph.D., principal investigator of the Center for Neuroscience Research at Children’s National. “We hope a small amount of blood donated by patients with FASD reveal the changes. Meanwhile, my group has also been optimizing drug candidates that reverse the epigenetic changes toward clinical trials.”

Advances in genetics and genomics have led to discoveries about the timing of exposure and developmental outcomes and genetic and epigenetic signatures that may be protective or harmful in terms of how in utero alcohol exposure affects developmental outcomes.

The hold-up in the field

While the exact number of people with FASDs is unknown, the National Institutes of Health estimates that 1% to 5% of the population have FASDs. FASDs has a spectrum of diagnoses that represent a broad range of effects that can be manifested in an individual whose mother drank alcohol during pregnancy. These conditions can affect everyone in different ways and range from mild to severe. Individuals with mild conditions may go undiagnosed. The more affected individuals have comorbid attention-deficit/hyperactivity disorder (ADHD) and behavioral problems that become the focus of clinical encounters. The individual’s health care provider may not recognize the core features as part of FASD.

“Because there is a stigma associated with drinking while pregnant, many providers fail to get this history, and women may be reluctant to offer this information,” said Andrea Gropman, M.D., division chief of Neurodevelopmental Pediatrics and Neurogenetics at Children’s National. “There are subtle and more obvious facial dysmorphology that may help with suspicion or identification, but many individuals do not have these findings.”

The core features may be nonspecific, such as intellectual disabilities and problems with behavior and learning, difficulties with math, memory, attention, judgment and poor impulse control, which are frequent findings in ADHD, autism, learning disorders and other conditions.

“Unless history is taken and FASD is in the differential diagnosis, the diagnosis may not be made,” said Dr. Gropman. “Individuals with FASD may feel stigmatized and opt not to participate in clinical trials.”

As mentioned by Dr. Gropman, stigma can make a patient family be reluctant to seek treatment, and thus the development of treatment for FASD cannot make significant progress to date, Hashimoto-Torii added.

Children’s National Hospital leads the way in an IRB approved study

Researchers at Children’s National have identified a potential drug candidate that reverse the epigenetic changes and may lead to clinical trials. The team is seeking people to participate in an IRB approved study. The study will involve cognitive testing, filling out surveys about current functioning and cheek swab and blood sample to determine if these changes are seen in patients. To participate, subjects must be

Children between the ages 5-12 with prenatal alcohol exposure.
Mother of child recruited above.

For participation, please contact Grace Johnson, research coordinator at to screen for eligibility at 202-476-6034 or gjohnson3@childrensnational.org

Meet the multidisciplinary team with different yet complementary skills in different fields, such as basic science, medical, social sciences, neurology and developmental disabilities, and development, who are working tirelessly to address the complex health problem.

Gropman lab:

Andrea Gropman, M.D., received her medical doctorate degree from the University of Massachusetts Medical School and specializes in neurogenetics, with a focus on mitochondrial disorders and Smith Magenis syndrome. Her latest research focuses on atypical patterns of inheritance, childhood mitochondrial disorders and other inborn errors of metabolism presenting with white matter disease.

Meira Meltzer, M.A., M.S., C.G.C., genetic counselor with a demonstrated history of working in the hospital and healthcare industry. Also skilled in molecular biology, clinical research and medical education. Strong healthcare services professional with a M.S. focused on genetic counseling from Brandeis University.

Cathy Scheiner, M.D., developmental behavioral pediatrician with a special interest in attention-deficit / hyperactivity disorder (ADHD), cerebral palsy and premature infant.

Grace Johnson, research assistant.

Hashimoto-Torii Lab:

Kazue Hashimoto-Torii, Ph.D., received her postdoctoral training in the Pasko Rakic laboratory at Yale University. Her research focuses on neurobehavior problems of children that stem from their environment during development, such as prenatal exposure to alcohol, drug and high-level glucose. A few drug candidates that her lab discovered have been patented and her lab is currently working hard to bring those medicines to bedside.

Satoshi Yamashita, M.D., Ph.D., postdoctoral research fellow skilled in developmental neurobiology. He is a pediatrician with Japanese medical license and received his Ph.D. with iPS cell research for STXBP1 encephalopathy in Japan.

Chiho Yamashita, B.N., research assistant passionate about child disease research. She is a nurse with a Japanese nursing license and worked in the pediatric department in Japan.

Primary cilia safeguard cortical neurons from environmental stress-induced dendritic degeneration

December 21, 2020

Fetus and neonates are under the risk of exposure to various external agents, such as alcohol and anesthetics taken by the mother. However, primary cilia can protect neurons by activating cilia-localized molecular signaling that inhibits degeneration of neuronal processes, according to the study’s findings.

A new study led by Kazue Hashimoto-Torii, Ph.D. and Masaaki Torii, Ph.D., both principal investigators for the Center for Neuroscience Research at Children’s National Hospital, found that primary cilia – tiny hair-like protrusions from the body of neuronal cells – protect neurons in the developing brain from adverse impacts of prenatal exposure.

Fetus and neonates are under the risk of exposure to various external agents, such as alcohol and anesthetics taken by the mother. However, primary cilia can protect neurons by activating cilia-localized molecular signaling that inhibits degeneration of neuronal processes, according to the study’s findings.

“Remarkably, the developing brain is equipped with intrinsic cell protection that helps to minimize the adverse impacts of to various external agents,” said Dr. Hashimoto-Torii. “However, the mechanisms of such protection have been unclear. Our study provides the first evidence that the tiny hair-like organelle protects neurons in the perinatal brain from adverse impacts of such external agents taken by the mother.”

The findings suggest that subtle alterations in primary cilia due to genetic conditions may lead to various neurodevelopmental disorders if combined with exposure to external agents from the environment. The findings also suggest that ciliopathy patients who have abnormal ciliary function due to genetic causes may have increased risk of abnormal brain development upon exposure to external agents.

“Clarifying diverse roles of cilia provides essential information for clinicians and patients with potential deficits in primary cilia to take extra precautions to avoid the risks for long-term negative impacts of external factors,” Dr. Torii explained. “We hope that further studies will define the whole picture of cilia-mediated neuroprotection and help us to advance our understanding of its importance in the pathogenesis of neurodevelopmental disorders.

This may ultimately lead to the development of treatment for various neurodevelopmental disorders,” he added.

The uniqueness of the study stems from the investigation of the role of cilia in brain development at the risk of exposure to various external factors that occur in the real world. Little is known about how the normal and abnormal brain development progresses in an environment where many external factors interact with intrinsic cellular mechanisms.

The study is a collaboration with researchers at Yale University and Keio University, Japan. Other Children’s National researchers who contributed to this study include Seiji Ishii, Ph.D.; Nobuyuki Ishibashi, M.D.; Toru Sasaki, M.D., Ph.D.; Shahid Mohammad, Ph.D.; Hye Hwang; Edwin Tomy; and Fahad Somaa.

U.S. DoD awards $2M for study to protect neurological function after cardiac surgery

July 2, 2020

A collaboration between clinical and basic science researchers including Drs. Ishibashi, Hashimoto-Torii, Jonas, and Deutsch, seeks to to understand how caspase enzyme activation plays a role in the development of fine and gross motor skills in children who underwent cardiac surgery for CHD repair.

The U.S. Department of Defense has awarded $2 million to Children’s National Hospital to study how a family of protease enzymes known as caspases may contribute to brain cell degeneration when activated by prolonged anesthesia and cardiopulmonary bypass during cardiac surgery for congenital heart disease.

This U.S. Army Medical Research Acquisition Activity Award, Anesthesia Neurotoxicity in Congenital Heart Disease, is led by principal investigator Nobuyuki Ishibashi, M.D., with both clinical and basic science co-investigators including Kazue Hashimoto-Torii, Ph.D., (Neuroscience), Richard Jonas , M.D., (Cardiovascular Surgery) and Nina Deutsch, M.D., (Anesthesiology).

While the specific cellular and molecular mechanisms of how anesthesia and cardiac surgery impact cortical development are poorly understood, both seem to impact brain growth and development in young children. The most common neurologic deficit seen in children after CHD surgical repair is the impairment of fine and gross motor skills.

Both anesthetic agents and inflammation like that seen as a result of cardiopulmonary bypass have also been shown to contribute to the activation of a specific group of enzymes that play an essential role in the routine (programmed) death of cells: caspases. However, recent pre-clinical research shows that these enzymes may also contribute to other alterations to cells beyond cell death, including making changes to other cell structures. In pre-clinical models, these changes cause impairments to fine and gross motor skills – the same neurological deficits seen in children with CHD who have undergone procedures requiring prolonged anesthesia and cardiopulmonary bypass.

The research team hypothesizes that caspases are extensively activated as a result of cardiac surgery and while that activation is rarely causing reduced numbers of neurons, the changes that caspase enzymes trigger in neurons are contributing to neurological deficits seen in children with CHD after surgery.

While the study focuses specifically on the impacts of cardiac surgery for correction of a heart defect, the findings could have major implications for any pediatric surgical procedure requiring prolonged anesthesia and/or cardiopulmonary bypass.

Center for Neuroscience Research investigators join CIFASD

July 17, 2017

Kazue Hashimoto-Torii and Masaaki Torii, Collaborative Initiative on Fetal Alcohol Spectrum Disorders

Masaaki Torii, Ph.D., Kazue Hashimoto-Torii, Ph.D., and their research teams are joining Collaborative Initiative on Fetal Alcohol Spectrum Disorders, a consortium supported by the National Institutes of Health.

Kazue Hashimoto-Torii, Ph.D., Masaaki Torii, Ph.D., and the research teams they lead have joined a national research consortium for Fetal Alcohol Spectrum Disorders that is supported by the National Institutes of Health (NIH).

The Collaborative Initiative on Fetal Alcohol Spectrum Disorders (CIFASD) aims to leverage multidisciplinary approaches to develop effective interventions and treatments for Fetal Alcohol Spectrum Disorders.

“Both of our labs have been fortunate in receiving multiple R series research grants from the NIH. I am deeply honored that we now join this prestigious national consortium, which opens additional opportunities to collaborate with other labs with neurobehavioral, genetics and facial dysmorphology expertise as well as other specialized disciplines,” says Hashimoto-Torii, principal investigator in the Center for Neuroscience Research at Children’s National Health System.

Fetal Alcohol Spectrum Disorders are a constellation of conditions that result from exposure to alcohol in the womb that reflect the vastly different ways fetuses respond to that in utero insult. While early intervention is crucial, one challenge that continues to bedevil the field is trying to determine which pregnancies are most at risk.

“It is crucial to develop early and precise biomarkers for predicting children’s risk for cognitive and behavioral problems,” Hashimoto-Torii says. “Our labs will work on developing a novel approach for identifying such biomarkers.”

The Children’s researchers will examine epigenetic changes at the single cell level that may provide the earliest hint of cognitive and learning difficulties – long before children show any symptoms of such problems. Hashimoto-Torii’s lab will perform single-cell droplet digital polymerase chain reaction (PCR) based biomarker analysis of blood samples from experimental models and humans. Meanwhile, the lab run by Torii – also a principal investigator in the Center for Neuroscience Research – will collect blood samples from experimental models, perform comprehensive behavioral analysis, and evaluate potential correlations between behaviors seen in the experimental models and their drop-PCR results.

“Under the auspices of CIFASD, we ultimately hope to link these biomarkers from our lab with results that our colleagues are seeing in children in order to validate their ability to accurately predict outcomes from prenatal alcohol exposure,” she says.

A brain’s protector may also be its enemy

May 12, 2017

By looking back to the earliest moments of embryonic brain development, Kazue Hashimoto-Torii, Ph.D. and her collaborators sought to explain the molecular and cellular bases for complex congenital brain disorders that can result from exposure to harmful agents.

When the brain is exposed to an environmental stressor all is not immediately lost. Brain cells have mechanisms that protect them against the ravages of alcohol and other toxic substances. One of these is a protein the cells make, known as Heat Shock Factor 1 (Hsf1), which helps to shield them from damage. The fetal brain also can make Hsf1, which protects its particularly vulnerable cells from environmental stressors that pregnant mothers are exposed to during gestation.

However, a new study suggests that this system is not perfect. Research led by Children’s National Health System scientists suggests that when too much Hsf1 is produced, it actually can impair the brain during development. While this finding was made in a preclinical model, it raises questions about neural risks for human infants if their mothers drink alcohol in the first or second trimester of pregnancy.

When fetuses are chronically exposed to harmful agents such as alcohol, ethanol or methyl mercury in utero, the experience can negatively affect fetal brain development in unpredictable ways. Some fetal brains show little or no damage, while others suffer severe damage. By looking at the earliest moments of embryonic brain development, an international research team that includes five Children’s National authors sought to explain the molecular and cellular bases for complex congenital brain disorders that can result from exposure to such harmful agents.

“From a public health perspective, there is ongoing debate about whether there is any level of drinking by pregnant women that is ‘safe,’ ” says Kazue Hashimoto-Torii, Ph.D., principal investigator in the Center for Neuroscience Research at Children’s National and senior author of the paper published May 2 in Nature Communications. “We gave ethanol to pregnant preclinical models and found their offspring’s neural cells experienced widely differing responses to this environmental stress. It remains unclear which precise threshold of stress exposure represents the tipping point, transforming what should be a neuroprotective response into a damaging response. Even at lower levels of alcohol exposure, however, the risk for fetal neural cells is not zero,” Hashimoto-Torii adds.

The cerebral cortex – the thin outer layer of the cerebrum and cerebellum that enables the brain to process information – is particularly vulnerable to disturbances in the womb, the study authors write. To fend off insult, neural cells employ a number of self-preservation strategies, including launching the protective Hsf1-Heat shock protein (Hsp) signaling pathway that is used by a wide range of organisms, from single-cell microbes to humans. Developing fetuses activate Hsf1-Hsp signaling upon exposure to environmental stressors, some to no avail.

To help unravel the neurological mystery, the researchers used a method that allows a single molecule to fluoresce during stress exposure. They tapped specific environmental stressors, such as ethanol, hydrogen peroxide and methyl mercury – each of which are known to produce oxidative stress at defined concentrations. And, using an experimental model, they examined the Hsf1 activation pattern in the developing cerebral cortex by creating a marker, an encoding gene tagged with a type of fluorescent protein that makes it glow bright red.

“Our results suggest that heterogeneous events of abnormal brain development may occur probabilistically – which explains patterns of cortical malformations that vary with each individual, even when these individuals are exposed to similar levels of environmental stressors,” Hashimoto-Torii adds.

Among the more striking findings, neural cells with excessively high levels of Hsf1-Hsp activation due to ethanol exposure experience disruptions to normal development, with delayed migration by immature cortical neurons. For the fetal brain to develop normally, neurons need to migrate to precise places in the brain at just the right time to enable robust neural connections. When neurons fail to arrive at their destinations or get there too late, there can be gaps in the neural network, compromising efficient and effective communication across the brain’s various regions.

“Even a short period of Hsf1 overactivation during prenatal development causes critical neuronal migration deficiency. The severity of deficiency depends on the duration of Hsf1 overactivation,” Hashimoto-Torii says. “Expression patterns vary, however, across various tissues. Stochastic response within individual cells may be largely responsible for variability seen within tissue and organs.”

The research team found one bright spot: Cortical neurons that stalled due to lack of the microtubule-associated molecule Dcx were able to regain their ability to migrate properly when the gene was replenished after birth. A reduction in Hsf1 activity after birth, however, did not show the same ability to trigger the “reset” button on neural development.

“The finding suggests that genes other than microtubule-associated genes may play pivotal roles in ensuring that migrating neurons reach their assigned destinations in the brain at the right time – despite the added challenge of excessive Hsf1 activation,” according to Hashimoto-Torii.

Tracking environmental stress damage in the brain

March 28, 2017

A team led by Children’s National developed a fluorescence reporter system in an experimental model that can single out neurons that have survived prenatal damage but remain vulnerable after birth.

PDF Version

What’s known

When fetuses are exposed to environmental stressors, such as maternal smoking or alcohol consumption, radiation or too little oxygen, some of these cells can die. A portion of those that survive often have lingering damage and remain more susceptible to further environmental insults than healthy cells; however, researchers haven’t had a way to identify these weakened cells. This lack of knowledge has made it difficult to discover the mechanisms behind pathological brain development thought to arise from these very early environmental exposures, as well as ways to prevent or treat it.

What’s new

A team led by Kazue Hashimoto-Torii, Ph.D., a principal investigator in the Center for Neuroscience Research at Children’s National Health System, developed a marker that makes a protein known as Heat Shock Factor 1 glow red. This protein is produced in cells that become stressed through exposure to a variety of environmental insults. Gestation is a particularly vulnerable time for rapidly dividing nerve cells in the fetal brain. Tests showed that this marker worked not just on cells in petri dishes but also in an experimental model to detect brain cells that were damaged and remained vulnerable after exposure to a variety of different stressors. Tweaks to the system allowed the researchers to follow the progeny of cells that were affected by the initial stressor and track them as they divided and spread throughout the brain. By identifying which neurons are vulnerable, the study authors say, researchers eventually might be able to develop interventions that could slow or stop damage before symptoms arise.

Questions for future research

Q: How do different environmental insults damage brain cells during gestation?
Q: How does this damage translate into pathology in organisms as they mature?
Q: Do the progeny of damaged brain cells retain the same degree of damage as they divide and spread?
Q: Can this new detection system be used to find and track damage in other organs, such as the heart, eye and liver?

Source: Torii, M., S. Masanori, Y.W. Chang, S. Ishii, S.G. Waxman, J.D. Kocsis, P. Rakic and K. Hashimoto-Torii. “Detection of vulnerable neurons damaged by environmental insults in utero.” Published Dec. 22, 2016 by Proceedings of the National Academy of Sciences. doi: 10.1073/pnas.1620641114

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