One of the first human studies on how mitochondrial function impacts immune cells to guide future treatments
In a new study, National Institutes of Health (NIH) researchers found that altered B cell function in children with mitochondrial disorders led to a weaker and less diverse antibody response to viral infections. The study, published in Frontiers in Immunology, was led by researchers at the National Human Genome Research Institute (NHGRI), who analyzed the gene activities of immune cells in children with mitochondrial disorders and found that B cells, which produce antibodies to fight viral infections, are less able to survive cellular stress.
“Our work is one of the first examples to study how B cells are affected in mitochondrial disease by looking at human patients,” said Eliza Gordon-Lipkin, M.D., assistant research physician in NHGRI’s Metabolism, Infection and Immunity Section and co-first author of the paper.
Mitochondria are important components of nearly every cell in the body because they convert food and oxygen into energy. Genomic variants in more than 350 genes have been linked to mitochondrial disorders with varied symptoms depending on which cells are affected.
“For children with mitochondrial disorders, infections can be life threatening or they can worsen the progression of their disorder,” said Peter McGuire, M.B.B.Ch., NHGRI investigator, head of the Metabolism, Infection and Immunity Section and senior author of the study. “We wanted to understand how immune cells differ in these patients and how that influences their response to infections.”
Finding could point toward more effective treatments that could potentially prevent cancer relapse.
A new study suggests that cells preparing to divide can reverse this process and return to a resting state, challenging long-held beliefs about cell division. If interrupted early in their preparation to divide, cells were able to halt the division process, known as mitosis. The finding, led by researchers at the National Cancer Institute (NCI), part of the National Institutes of Health, and reported July 5, 2023, in Nature, could point toward more effective treatments to interrupt the process by which cancer cells divide quickly and spread.
When cells receive growth-promoting signals, called mitogens, they enter the cell cycle —synthesize new copies of their DNA in a series of steps that culminate in cell division. Scientists have long thought that the preparatory stage of this cycle includes a point after which cells cannot halt the process. Researchers believed that after this “point of no return,” growth signals are no longer needed to drive cells to divide.
In the new study, scientists at NCI’s Center for Cancer Research captured videos of thousands of cells undergoing mitosis and watched what happened to those cells when mitogens were withdrawn. About 15 percent of the cells exited the cell cycle and returned to a resting state. What those cells had in common was that they hadn’t been as far along as others in the cycle when they stopped receiving growth-promoting signals. In experiments with many different kinds of cells, researchers found that all types of cells were capable of exiting the cell cycle if it was early enough.
A relative of jellyfish and corals regrows its entire body with help from “aging” cells
Insights into healing and aging were discovered by National Institutes of Health researchers and their collaborators, who studied how a tiny sea creature regenerates an entire new body from only its mouth. The researchers sequenced RNA from Hydractinia symbiolongicarpus, a small, tube-shaped animal that lives on the shells of hermit crabs. Just as the Hydractinia were beginning to regenerate new bodies, the researchers detected a molecular signature associated with the biological process of aging, also known as senescence. According to the study published in Cell Reports, Hydractinia demonstrates that the fundamental biological processes of healing and aging are intertwined, providing new perspective on how aging evolved.
“Studies like this that explore the biology of unusual organisms reveal both how universal many biological processes are and how much we have yet to understand about their functions, relationships and evolution,” said Charles Rotimi, Ph.D., director of the Intramural Research Program at the National Human Genome Research Institute (NHGRI), part of NIH. “Such findings have great potential for providing novel insights into human biology.”
Untangling the evolutionary origins of fundamental biological processes, such as aging and healing, is essential to understanding human health and disease. Humans have some capacity to regenerate, like healing a broken bone or even regrowing a damaged liver. Some other animals, such as salamanders and zebrafish, can replace entire limbs and replenish a variety of organs. However, animals with simple bodies, like Hydractinia, often have the most extreme regenerative abilities, such as growing a whole new body from a tissue fragment.
A regenerative role for senescence stands in contrast to findings in human cells. “Most studies on senescence are related to chronic inflammation, cancer and age-related diseases,” said Andy Baxevanis, Ph.D., senior scientist at NHGRI and an author of the study. “Typically, in humans, senescent cells stay senescent, and these cells cause chronic inflammation and induce aging in adjacent cells. From animals like Hydractinia, we can learn about how senescence can be beneficial and expand our understanding of aging and healing.”
Genome sequencing reveals genetic basis for disabling pansclerotic morphea, a severe inflammatory disease
Researchers at the National Institutes of Health and their colleagues have identified genomic variants that cause a rare and severe inflammatory skin disorder, known as disabling pansclerotic morphea, and have found a potential treatment. Scientists discovered that people with the disorder have an overactive version of a protein called STAT4, which regulates inflammation and wound healing. The work also identified a drug that targets an important feedback loop controlled by the STAT4 protein and significantly improves symptoms in these patients. The results were published in the New England Journal of Medicine.
Only a handful of patients have been diagnosed with disabling pansclerotic morphea, a disorder first described in the medical literature around 100 years ago. The disorder causes severe skin lesions and poor wound healing, leading to deep scarring of all layers of the skin and muscles. The muscles eventually harden and break down while the joints stiffen, leading to reduced mobility. Because the disorder is so rare, its genetic cause had not been identified until now.
“Researchers previously thought that this disorder was caused by the immune system attacking the skin,” said Sarah Blackstone, a predoctoral fellow within NHGRI's Inflammatory Disease Section, a medical student at the University of South Dakota, and co-first author of the study. “However, we found that this is an oversimplification, and that both skin and the immune system play an active role in disabling pansclerotic morphea.”
Data are the first nationwide estimates on the incidence of new chronic pain and new high impact chronic pain
A study from the National Institutes of Health shows that new cases of chronic pain occur more often among U.S. adults than new cases of several other common conditions, including diabetes, depression, and high blood pressure. Among people who have chronic pain, almost two-thirds still suffer from it a year later. These findings come from a new analysis of National Health Interview Survey (NHIS) data by investigators from the National Center for Complementary and Integrative Health (NCCIH) at the NIH, Seattle Children’s Research Institute, and University of Washington, Seattle, and are published in JAMA Network Open.
“Understanding incidence, beyond overall prevalence, is critical to understanding how chronic pain manifests and evolves over time. These data on pain progression stress the need for increased use of multimodal, multidisciplinary interventions able to change the course of pain and improve outcomes for people,” said Richard Nahin, Ph.D., lead author and lead epidemiologist at NCCIH.
Overall, the study found that the rate of chronic pain and high-impact chronic pain (HICP) among adults is approximately 21 percent and 8 percent, respectively. Chronic pain is pain that is experienced on most days or every day in the past three months; and HICP is pain that limits life or work activities on most days or every day during the past three months. The links between the widespread burden of chronic pain and the country’s opioid epidemic underscore the urgency to understand and address the issue of pain.
Findings may aid design of targeted drug delivery into the brain and central nervous system
Researchers at the National Institutes of Health and colleagues have developed a zebrafish model that provides new insight into how the brain acquires essential omega-3 fatty acids, including docosahexaenoic acid (DHA) and linolenic acid (ALA). Their findings, published in Nature Communications, have the potential to improve understanding of lipid transport across the blood-brain barrier and of disruptions in this process that can lead to birth defects or neurological conditions. The model may also enable researchers to design drug molecules that are capable of directly reaching the brain.
Omega-3 fatty acids are considered essential because the body cannot make them and must obtain them through foods, such as fish, nuts and seeds. DHA levels are especially high in the brain and important for a healthy nervous system. Infants obtain DHA from breastmilk or formula, and deficiencies of this fatty acid have been linked to problems with learning and memory. To get to the brain, omega-3 fatty acids must pass through the blood-brain barrier via the lipid transporter Mfsd2a, which is essential for normal brain development. Despite its importance, scientists did not know precisely how Mfsd2a transports DHA and other omega-3 fatty acids.
In the study, the research team provides images of the structure of zebrafish Mfsd2a, which is similar to its human counterpart. The snapshots are the first to detail precisely how fatty acids move across the cell membrane. The study team also identified three compartments in Mfsd2a that suggest distinct steps required to move and flip fatty acids through the transporter, as opposed to movement through a linear tunnel or along the surface of the protein complex. The findings provide key information on how Mfsd2a transports omega-3 fatty acids into the brain and may enable researchers to optimize drug delivery via this route. The study also provides foundational knowledge on how other members of this transporter family, called the major facilitator superfamily (MFS), regulate important cellular functions.
Discovery provides potential clues for Lewy body and frontotemporal dementias
Scientists at the National Institutes of Health have identified new genetic risk factors for two types of non-Alzheimer’s dementia. These findings were published in Cell Genomics and detail how researchers identified large-scale DNA changes, known as structural variants, by analyzing thousands of DNA samples. The team discovered several structural variants that could be risk factors Lewy body dementia (LBD) and frontotemporal dementia (FTD). The project was a collaborative effort between scientists at the National Institute of Neurological Disorders and Stroke (NINDS) and the National Institute on Aging (NIA) at NIH.
Structural variants have been implicated in a variety of neurological disorders. Unlike more commonly studied mutations, which often affect one or a few DNA building blocks called nucleotides, structural variants represent at least 50 but often hundreds, or even thousands, of nucleotides at once, making them more challenging to study.
“If you imagine that our entire genetic code is a book, a structural variant would be a paragraph, page, or even an entire chapter that has been removed, duplicated, or inserted in the wrong place,” said Sonja W. Scholz, M.D., Ph.D., investigator in the neurogenetics branch of NINDS and senior author of this study.
Findings offer insight into biological mechanisms, pointing to possible treatments
Twelve people with persistent neurological symptoms after SARS-CoV-2 infection were intensely studied at the National Institutes of Health (NIH) and were found to have differences in their immune cell profiles and autonomic dysfunction. These data inform future studies to help explain persistent neurological symptoms in Long COVID. The findings, published in Neurology: Neuroimmunology & Neuroinflammation, may lead to better diagnoses and new treatments.
People with post-acute sequelae of COVID-19 (PASC), which includes Long COVID, have a wide range of symptoms, including fatigue, shortness of breath, fever, headaches, sleep disturbances, and 'brain fog,' or cognitive impairment. Such symptoms can last for months or longer after an initial SARS-CoV-2 infection. Fatigue and 'brain fog' are among the most common and debilitating symptoms, and likely stem from nervous system dysfunction.
Researchers used an approach called deep phenotyping to closely examine the clinical and biological features of Long COVID in 12 people who had long-lasting, disabling neurological symptoms after COVID-19. Most participants had mild symptoms during their acute infection. At the NIH Clinical Center, participants underwent comprehensive testing, which included a clinical exam, questionnaires, advanced brain imaging, blood and cerebrospinal fluid tests, and autonomic function tests.
The results showed that people with Long COVID had lower levels of CD4+ and CD8+ T cells — immune cells involved in coordinating the immune system’s response to viruses — compared to healthy controls. Researchers also found increases in the numbers of B cells and other types of immune cells, suggesting that immune dysregulation may play a role in mediating Long COVID.
NIH study highlights the need to proactively screen for, prevent, and treat cannabis use disorder especially among young people
Young men with cannabis (marijuana) use disorder have an increased risk of developing schizophrenia, according to a study led by researchers at the Mental Health Services in the Capital Region of Denmark and the National Institute on Drug Abuse (NIDA) at the National Institutes of Health. The study, published in Psychological Medicine, analyzed detailed health records data spanning five decades and representing more than six million people in Denmark to estimate the fraction of schizophrenia cases that could be attributed to cannabis use disorder on the population level.
Researchers found strong evidence of an association between cannabis use disorder and schizophrenia among men and women, though the association was much stronger among young men. Using statistical models, the study authors estimated that as many as 30 percent of cases of schizophrenia among men aged 21-30 might have been prevented by averting cannabis use disorder.
Cannabis use disorder and schizophrenia are serious, but treatable, mental disorders that can profoundly impact people’s lives. People with cannabis use disorder are unable to stop using cannabis despite it causing negative consequences in their lives. Schizophrenia is a serious mental illness that affects how a person thinks, feels, and behaves. People with schizophrenia may seem like they have lost touch with reality, and the symptoms of schizophrenia can make it difficult to participate in usual, everyday activities. However, effective treatments are available for both cannabis use disorder and schizophrenia.
“The entanglement of substance use disorders and mental illnesses is a major public health issue, requiring urgent action and support for people who need it,” said NIDA Director and study coauthor Nora Volkow, M.D. “As access to potent cannabis products continues to expand, it is crucial that we also expand prevention, screening, and treatment for people who may experience mental illnesses associated with cannabis use. The findings from this study are one step in that direction and can help inform decisions that health care providers may make in caring for patients, as well as decisions that individuals may make about their own cannabis use.”
Idiopathic CD4 lymphocytopenia leaves immune system vulnerable to other diseases, cancers
In an 11-year study, researchers at the National Institutes of Health have further characterized idiopathic CD4 lymphocytopenia (ICL), a rare immune deficiency that leaves people vulnerable to infectious diseases, autoimmune diseases and cancers. Researchers observed that people with the most severe cases of ICL had the highest risk of acquiring or developing several of the diseases associated with this immune deficiency. This study, published in the New England Journal of Medicine, was led by Irini Sereti M.D., M.H.S., and Andrea Lisco, M.D., Ph.D., of the HIV Pathogenesis Section in the Laboratory of Immunoregulation at the National Institute of Allergy and Infectious Diseases (NIAID), part of NIH, and conducted at the NIH Clinical Center.
ICL is a condition marked by too few CD4+ T-cells, which are a type of white blood cell. The clinical definition of ICL is a CD4+ T-cell count of less than 300 cells per cubic millimeter (mm³) of blood for at least six weeks, in the absence of any disease or therapy associated with reduced white blood cells. Unlike HIV, a virus that suppresses the immune system if left untreated, there is no evidence that ICL is transmitted from person to person, and it has no known cause. There are limited therapeutic options for ICL.
In this observational study, the NIAID researchers quantified immune cells and noted the presence of opportunistic infections—infections that typically only affect people with suppressed immune systems—and other clinical conditions among 91 participant volunteers with ICL. The most prevalent opportunistic infections were human papillomavirus-related diseases (in 29 percent of participants), cryptococcosis (24 percent), molluscum contagiosum (9 percent), and mycobacterial diseases other than tuberculosis (5 percent). Participants with CD4+ T-cell counts below 100 cells per mm³ had a more than five-fold higher risk of opportunistic infections than those with CD4+ T-cell counts above 100 cells. Cancer risk was also higher in individuals with the lowest CD4+ T-cell counts, but the risk of autoimmune disease was lower.