Research advances from the National Institutes of Health (NIH) Intramural Research Program (IRP) often make headlines. Read the news releases that describe our most recent findings:
Whether you’re shedding pounds with the help of effective new medicines, slimming down after weight loss surgery or cutting calories and adding exercise, there will come a day when the numbers on the scale stop going down, and you hit the dreaded weight loss plateau.
In a recent study, Kevin Hall, a researcher at the National Institutes of Health who specializes in measuring metabolism and weight change, looked at when weight loss typically stops depending on the method people were using todrop pounds. He broke down the plateau into mathematical models using data from high-quality clinical trials of different ways to lose weight to understand why people stop losing when they do. The study published Monday in the journal Obesity.
IRP researchers discover that TGFβ signaling governs immune cell function in the eye
A signaling pathway controlled by transforming growth factor beta (TGFβ) could be involved in the progression of age-related macular degeneration (AMD). Researchers at the National Eye Institute (NEI), part of the National Institutes of Health, have found that interrupting TGFβ signals to immune cells called microglia causes the cells to enter an activated, inflammatory state. These activated microglia damage the retina, the light-sensitive tissue at the back of the eye. This damage is similar to cellular effects observed in AMD, a common cause of vision loss among older Americans. The study was published today in the journal eLife.
Scientists have known for years that people with certain variations in genes in the TGFβ pathway may be more at risk for advanced AMD, which suggests that TGFβ might contribute to disease progression. In a healthy retina, neurons continuously emit a variety of signaling molecules, including TGFβ, which communicate to neighboring cells that all is well, or conversely, let those cells know if something is wrong. When microglia sense normal levels of these molecules, they adopt a branched shape connected with and maintaining the health of their neuron neighbors. But when the signals change, microglia can enter an activated state, where they move to sites of injury to remove damaged or dead cells.
“Communication between neurons and microglia in the retina is going on all the time. Neurons tell the microglia how to behave and how to be of service to the rest of the retina,” said Wai Wong, M.D., Ph.D., chief of the NEI section on neuron-glia interactions in retinal disease, who led the study. “We wanted to know whether there was a connection between this genetic risk involving TGFβ and abnormal retinal microglia, which are often found in AMD.”
In healthy retina (left), microglia (green) demonstrate a branched structure that covers the retina. Without TGFβ signaling (right), microglia lose their branched structure, and attach to blood vessels (white). Müller glia become abnormal and acquire activation markers (red).
Findings set stage for first clinical trial of stem cell-based therapeutic approach for AMD
Using a novel patient-specific stem cell-based therapy, researchers at the National Eye Institute (NEI) prevented blindness in animal models of geographic atrophy, the advanced "dry" form of age-related macular degeneration (AMD), which is a leading cause of vision loss among people age 65 and older. The protocols established by the animal study, published January 16 in Science Translational Medicine (STM), set the stage for a first-in-human clinical trial testing the therapy in people with geographic atrophy, for which there is currently no treatment.
"If the clinical trial moves forward, it would be the first ever to test a stem cell-based therapy derived from induced pluripotent stem cells (iPSC) for treating a disease," said Kapil Bharti, Ph.D., a Stadtman Investigator and head of the NEI Unit on Ocular and Stem Cell Translational Research. Bharti was the lead investigator for the animal-model study published in STM. The NEI is part of the National Institutes of Health.
The therapy involves taking a patient’s blood cells and, in a lab, converting them into iPS cells, which can become any type of cell in the body. The iPS cells are programmed to become retinal pigment epithelial cells, the type of cell that dies early in the geographic atrophy stage of macular degeneration. RPE cells nurture photoreceptors, the light-sensing cells in the retina. In geographic atrophy, once RPE cells die, photoreceptors eventually also die, resulting in blindness. The therapy is an attempt to shore up the health of remaining photoreceptors by replacing dying RPE with iPSC-derived RPE.
The researchers will take a patient’s own blood cells, and in a lab, convert them into iPS cells capable of becoming any type of cell in the body. The iPS cells are then programmed to become retinal pigment epithelial cells, the type of cell that dies early in the geographic atrophy form of AMD.
Algorithm could revolutionize cervical cancer screening, especially in low-resource settings
A research team led by investigators from the National Institutes of Health and Global Good has developed a computer algorithm that can analyze digital images of a woman’s cervix and accurately identify precancerous changes that require medical attention. This artificial intelligence (AI) approach, called automated visual evaluation, has the potential to revolutionize cervical cancer screening, particularly in low-resource settings.
To develop the method, researchers used comprehensive datasets to "train" a deep, or machine, learning algorithm to recognize patterns in complex visual inputs, such as medical images. The approach was created collaboratively by investigators at the National Cancer Institute (NCI) and Global Good, a fund at Intellectual Ventures, and the findings were confirmed independently by experts at the National Library of Medicine (NLM). The results appeared in the Journal of the National Cancer Institute on January 10, 2019. NCI and NLM are parts of NIH.
"Our findings show that a deep learning algorithm can use images collected during routine cervical cancer screening to identify precancerous changes that, if left untreated, may develop into cancer," said Mark Schiffman, M.D., M.P.H., of NCI’s Division of Cancer Epidemiology and Genetics, and senior author of the study. "In fact, the computer analysis of the images was better at identifying precancer than a human expert reviewer of Pap tests under the microscope (cytology)."
A global resource that includes data on thousands of inherited variants in the BRCA1 and BRCA2 genes is available to the public. The BRCA Exchange was created through the BRCA Challenge, a long-term demonstration project initiated by the Global Alliance for Genomics and Health (GA4GH) to enhance sharing of BRCA1 and BRCA2 data. The resource, available through a website and a new smartphone app, allows clinicians to review expert classifications of variants in these major cancer predisposition genes as part of their individual assessment of complex questions related to cancer prevention, screening, and intervention for high-risk patients.
The five-year BRCA Challenge project was funded in part by the National Cancer Institute (NCI), part of the National Institutes of Health, and through the Cancer Moonshot. A paper detailing the development of the BRCA Exchange was published Jan. 8, 2019, in PLOS Genetics.
“This project has yielded a meta-analysis of BRCA1 and BRCA2 variants collected from multiple sources to understand how experts annotate specific mutations in the two genes,” said Stephen J. Chanock, M.D., director of NCI’s Division of Cancer Epidemiology and Genetics and lead author of the paper. “There’s an urgent need for sharing data in cancer predisposition research. The BRCA Exchange is proof of principle that large-scale collaboration and data sharing can be achieved and can provide the latest and best quality information to enable clinicians and individuals to improve care.”
Results suggest a breakdown in brain cell waste system triggers a destructive immune reaction
In a study of fruit flies, NIH scientists suggested that the body’s immune system may play a critical role in the damage caused by aging brain disorders. The results are based on experiments in which the researchers altered the activity of Cdk5, a gene that preclinical studies have suggested is important for early brain development and may be involved in neurodegenerative diseases, such as ALS, Alzheimer’s and Parkinson’s disease. Previously, they found that altering Cdk5 sped up the genetic aging process, causing the flies to die earlier than normal and have problems with walking or flying late in life and greater signs of neurodegenerative brain damage.
In this study, published in Cell Reports, they suggested that altering Cdk5 resulted in the death of dopamine releasing neurons, especially in the brains of older flies. Typically, Parkinson’s disease damages the same types of cells in humans. Further experiments in flies suggested the neuron loss happened because altering Cdk5 slowed autophagy, or a cell’s waste disposal system that rids the body of damaged cells in a contained, controlled fashion, which in turn triggered the immune system to attack the animal’s own neurons. This immune system attack is a much “messier” and more diffuse process than autophagy. Genetically restoring the waste system or blocking the immune system’s responses prevented the reduction in dopamine neurons caused by altering Cdk5. The authors concluded that this chain reaction in which a breakdown in autophagy triggers a widely destructive immune reaction may occur in human brain during several neurodegenerative disorders and that researchers may want to look to these systems for new treatment targets and strategies.
In a study of flies, NIH scientists showed how the immune system may be a culprit in the damage caused by aging brain disorders.
Proximity to nearby muscle cells may make prostate cancer cells more likely to invade nearby tissues and spread to other organs, according to an early study by researchers at the National Institutes of Health. The presence of muscle cells appears to make cancer cells more likely to fuse two or more cancer cells into a single cell, thereby increasing their invasiveness and ability to spread. The study was led by Berna Uygur, Ph.D., of NIH’s Eunice Kennedy ShriverNational Institute of Child Health and Human Development (NICHD) and includes colleagues from the National Eye Institute and the Maine Medical Center Research Institute in Scarborough. The study appears in Molecular Cancer Research.
Researchers grew human prostate cancer cells in laboratory dishes along with human muscle cells — stand-ins for the smooth muscle surrounding the prostate gland and the striated muscle of the urethral sphincter at the base of the prostate. The muscle cells secreted interleukins 4 and 13, cellular proteins that stimulated the cancer cells to produce two additional proteins, annexin A5 and syncytin 1, which triggered the cancer cells to fuse together. Testing revealed that the fused cells developed characteristics of more malignant cells, which are more likely to invade surrounding tissues and spread to other parts of the body. The researchers note that drugs to inhibit annexin A5 and syncytin 1 could be studied for their potential to treat prostate cancer. According to the National Cancer Institute, approximately 11.2 percent of men in the United States will be diagnosed with prostate cancer at some point during their lifetime.
From left to right: prostate cancer cells (square) near skeletal (oblong) and smooth (oval) muscle cells respond to Interleukins 4 and 13 (IL4/13) by producing annexin A5 and syncytin 1 (Syn1 & AnxA5) and fusing. Fused cells (starburst) develop increased capacity to invade tissue and spread.
Findings could lead to early diagnosis, better treatment studies
An ultrasensitive test has been developed that detects a corrupted protein associated with Alzheimer’s disease and chronic traumatic encephalopathy (CTE), a condition found in athletes, military veterans, and others with a history of repetitive brain trauma. This advance could lead to early diagnosis of these conditions and open new research into how they originate, according to National Institutes of Health scientists and their colleagues. In their new study, published in Acta Neuropathologica, the researchers explain how they adapted a diagnostic test originally developed for prion diseases to detect abnormal clusters of tau protein. Like other proteins involved in neurological diseases, tau protein clusters can seed themselves and contribute substantially to the disease processes of Alzheimer’s and CTE. The study involved brain samples from 16 Alzheimer’s patients, two boxers with CTE, and numerous control cases involving other brain diseases.
The test is extremely sensitive. For example, if a pinhead-sized sample of brain tissue from an Alzheimer’s patient were pulverized and diluted into a thousand gallons of liquid, the test still could detect tau seeds in a pinhead-sized volume of that dilution. The test is called AD RT-QuIC: Alzheimer’s disease real-time quaking induced conversion.
Scientists at NIH’s National Institute of Allergy and Infectious Diseases developed RT-QuIC about a decade ago to detect Creutzfeldt-Jakob (CJD) and other prion diseases. Since then, they have repeatedly improved and adapted it to detect other neurological diseases, such as Parkinson’s and dementia with Lewy bodies. The test, which already is used in clinical settings to diagnose sporadic CJD, is noted for its rapid and accurate results.
Findings from a new study by researchers at the National Cancer Institute (NCI) show that patients treated with chemotherapy for most solid tumors during 2000–2014 experienced an increased risk of therapy-related myelodysplastic syndrome/acute myeloid leukemia (tMDS/AML). The study, which used U.S. population-based cancer registry data from NCI’s Surveillance, Epidemiology, and End Results (SEER) program and treatment information from the SEER–Medicare database, was published December 20, 2018, in JAMA Oncology. NCI is part of the National Institutes of Health.
Advances in treatment over the last several decades have resulted in improved survival for patients with many types of cancer. However, survivors may be at increased risk of developing a subsequent treatment-related cancer. In this study, researchers aimed to quantify the risk of developing tMDS/AML, a rare but often fatal blood cancer, in patients treated with chemotherapy.
“We’ve known for a long time that the development of myeloid leukemia is a very rare adverse effect of some types of cancer treatments that damage cells,” said Lindsay Morton, Ph.D., lead author of the study and a senior investigator in NCI’s Division of Cancer Epidemiology and Genetics. “There have been many changes in cancer treatment over time, including the introduction of new chemotherapy drugs and drug combinations, but we didn’t know what the risk of therapy-related leukemia looked like for patients since these changes were made.”
Breast cancer risk remains elevated 20-30 years after childbirth
In general, women who have had children have a lower risk of breast cancer compared to women who have never given birth. However, new research has found that moms don’t experience this breast cancer protection until many years later and may face elevated risk for more than 20 years after their last pregnancy.
Scientists at the National Institutes of Health, along with members of the international Premenopausal Breast Cancer Collaborative Group, found breast cancer risk increases in the years after a birth, with the highest risk of developing the disease about five years later. The findings, which appeared online in the Annals of Internal Medicine, suggest breast cancer protection from pregnancy may not begin until as many as 30 years after the birth of the last child.
According to senior author Dale Sandler, Ph.D., head of the Epidemiology Branch at the National Institute of Environmental Health Sciences (NIEHS), part of NIH, a few prior studies reported an increase in breast cancer risk after childbirth. However, most of what researchers knew about breast cancer risk factors came from studies of women who have gone through menopause. Since breast cancer is relatively uncommon in younger women, it is more difficult to study.
The study suggests breast cancer protection from pregnancy may not begin until as many as 30 years after the last pregnancy.
Study findings can immediately be applied to human patients with the disease
Researchers have discovered that a hormone, fibroblast growth factor 21 (FGF21), is extremely elevated in mice with liver disease that mimics the same condition in patients with methylmalonic acidemia (MMA), a serious genomic disorder. Based on this finding, medical teams treating patients with MMA will be able to measure FGF21 levels to predict how severely patients’ livers are affected and when to refer patients for liver transplants. The findings also might shed light on more common disorders such as fatty liver disease, obesity and diabetes by uncovering similarities in how MMA and these disorders affect energy metabolism and, more specifically, the function of mitochondria, the cells’ energy powerhouses. The study, conducted by researchers at the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health, was published Dec. 6 in JCI Insight.
“Findings from mouse studies usually take years to translate into health care treatment, but not in this case,” said Charles P. Venditti, M.D., Ph.D., senior author and senior investigator in the NHGRI Medical Genomics and Metabolic Genetics Branch. “We can use this information today to ensure that patients with MMA are treated before they develop severe complications.”
An electron micrograph showing abnormally shaped and structured mitochondria in the liver of a mutant mouse that models methylmalonic acidemia.
