Thursday, September 21, 2023

 

Genetic biomarker may predict severity of food allergy


Offers potential for determining the risk of severe reactions for patients and families with food allergies


Peer-Reviewed Publication

ANN & ROBERT H. LURIE CHILDREN'S HOSPITAL OF CHICAGO




Researchers from Ann & Robert H. Lurie Children’s Hospital of Chicago and colleagues reported for the first time that a genetic biomarker may be able to help predict the severity of food allergy reactions. Currently there is no reliable or readily available clinical biomarker that accurately distinguishes patients with food allergies who are at risk for severe life-threatening reactions versus more mild symptoms. Findings were published in the Journal of Allergy and Clinical Immunology.

Dr. Lang and colleagues found that the presence of an enzyme isoform called α-tryptase, which is encoded by the TPSAB1 gene, correlates with increased prevalence of anaphylaxis or severe reaction to food as compared to subjects without any α-tryptase.

“Determining whether or not a patient with food allergies has α-tryptase can easily be done in clinical practice using a commercially available test to perform genetic sequencing from cheek swabs,” said lead author Abigail Lang, MD, MSc, attending physician and researcher at Lurie Children’s and Assistant Professor of Pediatrics at Northwestern University Feinberg School of Medicine. “If the biomarker is detected, this may help us understand that the child is at a higher risk for a severe reaction or anaphylaxis from their food allergy and should use their epinephrine auto-injector if exposed to the allergen. Our findings also open the door to developing an entirely new treatment strategy for food allergies that would target or block α-tryptase. This is an exciting first step and more research is needed.”

Tryptase is found mainly in mast cells, which are white blood cells that are part of the immune system. Mast cells become activated during allergic reactions. Increased TPSAB1 copy number which leads to increased α-tryptase is already known to be associated with severe reactions in adults with Hymenoptera venom allergy (or anaphylaxis following a bee sting).

Dr. Lang’s study included 119 participants who underwent TPSAB1 genotyping, 82 from an observational food allergy cohort at the National Institute of Allergy and Infectious Diseases (NIAID) and 37 from a cohort of children who reacted to peanut oral food challenge at Lurie Children’s.

“We need to validate our preliminary findings in a much larger study, but these initial results are promising,” says Dr. Lang. “We also still need a better understanding of why and how α-tryptase makes food allergy reactions more severe in order to pursue this avenue for potential treatment.”

Rajesh Kumar, MD, MSc, from Lurie Children’s is the co-senior author on the study. Dr. Kumar is the Interim Division Head of Allergy and Immunology and Professor of Pediatrics at Northwestern University Feinberg School of Medicine.

This work was supported in part by the Midwest Allergy Research Institute (MARI) Food Allergy Pilot Research Award and NIAID-sponsored T32 grant AI083216. This project was funded in part with federal funds from the Division of Intramural Research of the National Institute of Allergy and Infectious Diseases, NIH. This project has also been funded in whole or in part with federal funds from the National Cancer Institute, National Institutes of Health, under Contract No. 75N91019D00024.

Research at Ann & Robert H. Lurie Children’s Hospital of Chicago is conducted through Stanley Manne Children’s Research Institute. The Manne Research Institute is focused on improving child health, transforming pediatric medicine and ensuring healthier futures through the relentless pursuit of knowledge. Lurie Children’s is a nonprofit organization committed to providing access to exceptional care for every child. It is ranked as one of the nation’s top children’s hospitals by U.S. News & World Report. Lurie Children’s is the pediatric training ground for Northwestern University Feinberg School of Medicine.

 

Newly discovered bone stem cell causes premature skull fusion


Peer-Reviewed Publication

WEILL CORNELL MEDICINE

Newly Discovered Bone Stem Cell Causes Premature Skull Fusion 

IMAGE: A CONCEPTUAL RENDERING OF HOW A NEW STEM CELL IN THE JOINTS BETWEEN THE FLAT BONES OF THE SKULL DRIVES SKULL GROWTH AND FUSION. view more 

CREDIT: AI IMAGE GENERATED USING MIDJOURNEY ON MAY 24, 2023; PROVIDED BY THE GREENBLATT LAB.



Craniosynostosis, the premature fusion of the top of the skull in infants, is caused by an abnormal excess of a previously unknown type of bone-forming stem cell, according to a preclinical study led by researchers at Weill Cornell Medicine.

Craniosynostosis arises from one of several possible gene mutations, and occurs in about one in 2,500 babies. By constricting brain growth, it can lead to abnormal brain development if not corrected surgically. In complex cases, multiple surgeries are needed.

In the study, which appears Sept. 20 in Nature, the researchers examined in detail what happens in the skull of mice with one of the most common mutations found in human craniosynostosis. They found that the mutation drives premature skull fusion by inducing the abnormal proliferation of a type of bone-making stem cell—the DDR2+ stem cell—that had never been described before.

“We can now start to think about treating craniosynostosis not just with surgery but also by blocking this abnormal stem cell activity,” said study co-senior author Dr. Matt Greenblatt, an associate professor of pathology and laboratory medicine at Weill Cornell Medicine and a pathologist at NewYork-Presbyterian/Weill Cornell Medical Center.

The other co-senior author of the study was Dr. Shawon Debnath, a research associate in the Greenblatt laboratory.

In a study published in Nature in 2018, Drs. Debnath and Greenblatt and their colleagues, described the discovery of a type of bone-forming stem cell they called the CTSK+ stem cell. Because this type of cell is present in the top of the skull, or “calvarium,” in mice, they suspected that it has a role in causing craniosynostosis.

In the new study, they investigated that possibility by engineering mice in which CTSK+ stem cells lack one of the genes whose loss of function causes craniosynostosis. They expected that the gene deletion somehow would induce these calvarial stem cells to go into bone-making overdrive. This new bone would fuse the flexible, fibrous material called sutures in the skull that normally allow it to expand in infants.

“We were surprised to find that, instead of the mutation in CTSK+ stem cells leading to these stem cells being activated to fuse the bony plates in the skull as we expected, mutations in the CTSK+ stem cells instead led to the depletion of these stem cells at the sutures—and the greater the depletion, the more complete the fusion of the sutures,” Dr. Debnath said.

The unexpected finding led the team to hypothesize that another type of bone-forming stem cell was driving the abnormal suture fusion. After further experiments, and a detailed analysis of the cells present at fusing sutures, they identified the culprit: the DDR2+ stem cell, whose daughter cells make bone using a different process than that utilized by CTSK+ cells.

The team found that CTSK+ stem cells normally suppress the production of the DDR2+ stem cells. But the craniosynostosis gene mutation causes the CTSK+ stem cells to die off, allowing the DDR2+ cells to proliferate abnormally.

To investigate these stem cells in human tissue, the team formed a collaboration with craniosynostosis surgeon Dr. Caitlin Hoffman, neurogeneticist Dr. Elizabeth Ross, and neuropathologist Dr. David Pisapia, all at Weill Cornell Medicine and NewYork-Presbyterian/Weill Cornell Medical Center; and craniosynostosis surgeon Dr. Thomas Imahiyerobo of Columbia University Vagelos College of Physicians and Surgeons and NewYork-Presbyterian/Columbia University Irving Medical Center.

The researchers found the human versions of DDR2+ stem cells and CTSK+ stem cells in calvarial samples from craniosynostosis surgeries—underscoring the likely clinical relevance of their findings in mice.

The findings suggest that inappropriate DDR2+ stem cell proliferation in the calvarium, in infants with craniosynostosis-linked gene mutations, could be treated by suppressing this stem cell population, through mimicking the methods that CTSK+ stem cells normally use to prevent expansion of DDR2+stem cells. The researchers found that the CTSK+ stem cells achieve this suppression by secreting a growth factor protein called IGF-1, and possibly other regulatory proteins.

“We observed that we could partly prevent calvarial fusion by injecting IGF-1 over the calvarium,” said study first author Dr. Seoyeon Bok, a postdoctoral researcher in the Greenblatt laboratory.

“I can imagine DDR2+ stem cell-suppressing drug treatments being used along with surgical management, essentially to limit the number of surgeries needed or enhance outcomes,” Dr. Greenblatt said.

In addition to treatment-oriented research, he and his colleagues now are looking for other bone-forming stem cell populations in the skull.

“This work has uncovered much more complexity in the skull than we ever imagined, and we suspect the complexity doesn’t end with these two stem cell types,” Dr. Greenblatt said.

 

Scientists reveal how the effects of psychosis spread throughout the brain


Scientists detail new capacity to map and model the spread of brain changes in people with different stages of psychoses


Peer-Reviewed Publication

MONASH UNIVERSITY

Professor Alex Fornito 

IMAGE: PROFESSOR ALEX FORNITO view more 

CREDIT: MONASH UNIVERSITY




Psychoses like schizophrenia cost billions of dollars annually and derail the lives of people struggling with the disease. Now Monash University researchers have modelled how the effects of psychosis spread through the brain, allowing them to isolate areas where these changes may originate from and which could be targeted by therapies designed to reduce the disease’s progression.

The study, published today in the prestigious Journal of the American Medical Association Psychiatry, details how the scientists were able to map and model the spread of brain changes in people with different stages of psychoses such as schizophrenia,from people newly diagnosed to those who have experienced psychosis for years.

The study, led by  Dr Sid Chopra , from the Turner Institute for Brain and Mental Health and Monash University’s School of Psychological Sciences,  identified the hippocampus, which is important for memory, as a possible  early site of brain changes in psychosis. “This finding could potentially guide  therapies that can target this area of the brain, potentially limiting the impact of the illness or perhaps even reducing the risk of psychosis onset,” he said

The study looked at 534 individuals from four groups, spanning early and late stages of psychotic illness. The researchers used MRI to examine changes in grey matter that occur at the different illness stages

They found that the evolution of psychoses, as measured by changes in great matter, may originate in the hippocampus and gradually  spread  across the brain, over time, via the nerve or axonal connections. According to Dr Chopra, “we found that the pattern of grey matter change seen in psychosis is not randomly distributed across the brain, but is shaped by a complex network of structural connections – in a very similar way to how we see the progression of neurodegenerative diseases in the brain.”

The researchers used a mathematical model to predict  grey matter volume changes  in four different groups of people with schizophrenia, scanned at both early and late stages of illness. According to Professor Alex Fornito, who led the research team, “we found consistent evidence that the hippocampus, an area important for memory and which is known to play an important role in schizophrenia, is a candidate epicentre of brain changes in the illness,” he said.

Importantly the researchers were able to distinguish brain changes associated with disease from those linked to  the use of antipsychotic medication. “Most research has taken place with people who are already taking antipsychotic medications, making it difficult to disentangle the effects of medication from those of  illness,” said Dr Chopra. “Our network-based model was able to account for both medication-related and illness-related brain changes, meaning that brain network architecture represents a fundamental constraint on both types of brain changes in psychosis.” 

According to Dr Chopra, the new approach opens new possibilities for understanding the causes of brain changes in schizophrenia, and for forecasting how they might evolve in individual patients. “Our work demonstrates that it is possible to investigate promising mechanisms behind widespread brain changes in schizophrenia, using fairly simple models” he said. “We hope to further extend these models to identify possible treatment targets and predict how the illness might evolve in individual people.”

 

 

Consumption of ultraprocessed food and risk of depression

JAMA Network Open

Peer-Reviewed Publication

JAMA NETWORK



About The Study: The findings of this study suggest that greater ultraprocessed food (UPF; i.e., energy-dense, palatable, and ready-to-eat items) intake, particularly artificial sweeteners and artificially sweetened beverages, is associated with increased risk of depression. Although the mechanism associating UPF to depression is unknown, recent experimental data suggests that artificial sweeteners elicit purinergic transmission in the brain, which may be involved in the etiopathogenesis of depression. 

Authors: Raaj S. Mehta, M.D., M.P.H., and Andrew T. Chan, M.D., M.P.H., of Massachusetts General Hospital and Harvard Medical School in Boston, are corresponding authors. 

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/ 

(doi:10.1001/jamanetworkopen.2023.34770)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

#  #  #

Embed this link to provide your readers free access to the full-text article

 http://jamanetwork.com/journals/jamanetworkopen/fullarticle/10.1001/jamanetworkopen.2023.34770?utm_source=For_The_Media&utm_medium=referral&utm_campaign=ftm_links&utm_term=092023

About JAMA Network Open: JAMA Network Open is an online-only open access general medical journal from the JAMA Network. On weekdays, the journal publishes peer-reviewed clinical research and commentary in more than 40 medical and health subject areas. Every article is free online from the day of publication. 

 

Genetically modifying individual cells in animals


Peer-Reviewed Publication

ETH ZURICH

Mouse 

IMAGE: WITH THE NEW METHOD, THE CELLS IN INDIVIDUAL ORGANS OF ANIMALS CAN BE GENETICALLY MODIFIED IN A MOSAIC-LIKE MANNER (SYMBOL IMAGE GENERATED WITH MIDJOURNEY). view more 

CREDIT: ETH ZURICH



One proven method for tracking down the genetic causes of diseases is to knock out a single gene in animals and study the consequences this has for the organism. The problem is that for many diseases, the pathology is determined by multiple genes. This makes it extremely difficult for scientists to determine the extent to which any one of the genes is involved in the disease. To do this, they would have to perform many animal experiments – one for each desired gene modification.

Researchers led by Randall Platt, Professor of Biological Engineering at the Department of Biosystems Science and Engineering at ETH Zurich in Basel, have now developed a method that will greatly simplify and speed up research with laboratory animals: using the CRISPR-Cas gene scissors, they simultaneously make several dozen gene changes in the cells of a single animal, much like a mosaic. While no more than one gene is altered in each cell, the various cells within an organ are altered in different ways. Individual cells can then be precisely analysed. This enables researchers to study the ramifications of many different gene changes in a single experiment.

First time in adult animals

For the first time, the ETH Zurich researchers have now successfully applied this approach in living animals – specifically, in adult mice – as they report in the current issue of Nature. Other scientists had previously developed a similar approach for cells in culture or animal embryos.

To “inform” the mice’s cells as to which genes the CRISPR-Cas gene scissors should destroy, the researchers used the adeno-associated virus (AAV), a delivery strategy that can target any organ. They prepared the viruses so that each virus particle carried the information to destroy a particular gene, then infected the mice with a mixture of viruses carrying different instructions for gene destruction. In this way, they were able to switch off different genes in the cells of one organ. For this study, they chose the brain.

New pathogenic genes discovered

Using this method, the researchers from ETH Zurich, together with colleagues from the University of Geneva, obtained new clues to a rare genetic disorder in humans, known as 22q11.2 deletion syndrome. Patients affected by the disease show many different symptoms, typically diagnosed with other conditions such as schizophrenia and autism spectrum disorder. Before now, it was known that a chromosomal region containing 106 genes is responsible for this disease. It was also known that the disease was associated with multiple genes, however, it was not known which of the genes played which part in the disease.

For their study in mice, the researchers focused on 29 genes of this chromosomal region that are also active in the mouse brain. In each individual mouse brain cell, they modified one of these 29 genes and then analysed the RNA profiles of those brain cells. The scientists were able to show that three of these genes are largely responsible for the dysfunction of brain cells. In addition, they found patterns in the mouse cells that are reminiscent of schizophrenia and autism spectrum disorders. Among the three genes, one was already known, but the other two had not previously been the focus of much scientific attention.

“If we know which genes in a disease have abnormal activity, we can try to develop drugs that compensate for that abnormality,” says António Santinha, a doctoral student in Platt’s group and lead author of the study.

Patent pending

The method would also be suitable for use in studying other genetic disorders. “In many congenital diseases, multiple genes play a role, not just one, Santinha says. “This is also the case with mental illnesses such as schizophrenia. Our technique now lets us study such diseases and their genetic causes directly in fully grown animals.” The number of modified genes could be increased from the current 29 to several hundred genes per experiment.

“It’s a big advantage that we can now do these analyses in living organisms, because cells behave differently in culture to how they do as part of a living body,” Santinha says. Another advantage is that the scientists can simply inject the AAVs into the animals’ bloodstreams. There are various different AAVs with different functional properties. In this study, researchers used a virus that enters the animals’ brains. “Depending on what you’re trying to investigate, though, you could also use AAVs that target other organs,” Santinha says.

ETH Zurich has applied for a patent on the technology. The researchers now want to use it as part of a spin-off they are establishing.

***

Perturbing the genome

The technique presented here is one of a series of new genetic editing methods used to alter the genome of cells in a mosaic-like manner. CRISPR perturbation is the technical term for this research approach that involves the perturbation of the genome using CRISPR-Cas gene scissors. This approach is currently revolutionising research in the life sciences. It makes it possible to obtain a great deal of information from a single scientific experiment. As a result, the approach has the potential to accelerate biomedical research, such as in the search for the molecular causes of genetically complex diseases.

A week ago, another research group from the Department of Biosystems Science and Engineering at ETH Zurich in Basel, working with a team from Vienna, published a study in which they applied CRISPR perturbation in organoids (see ETH News). Organoids are microtissue spheroids that are grown from stem cells and have a similar structure to real organs – in other words, they are a sort of miniature organ. They are an animal-free research method that complements research on animals. Because both methods – CRISPR perturbation in animals and in organoids – can provide more information with fewer experiments, both have the potential to ultimately reduce the number of animal experiments.

 

County-level sociodemographic characteristics and availability of COVID-19 therapeutic drugs


JAMA Network Open

Peer-Reviewed Publication

JAMA NETWORK



About The Study: The results of this study showed sociodemographic-based disparities in geographic clustering of COVID-19 therapeutic drugs, highlighting disparities in access to these drugs. With the end of the COVID-19 Public Health Emergency, these findings highlight an important gap in treatment access. 

Authors: Kosuke Tamura, Ph.D., of the National Institutes of Health in Bethesda, Maryland, is the corresponding author. 

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/ 

(doi:10.1001/jamanetworkopen.2023.34763)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support. 

http://jamanetwork.com/journals/jamanetworkopen/fullarticle/10.1001/jamanetworkopen.2023.34763?utm_source=For_The_Media&utm_medium=referral&utm_campaign=ftm_links&utm_term=092023

About JAMA Network Open: JAMA Network Open is an online-only open access general medical journal from the JAMA Network. On weekdays, the journal publishes peer-reviewed clinical research and commentary in more than 40 medical and health subject areas. Every article is free online from the day of publication.