It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Thursday, June 02, 2022
Mouse study links air pollution exposure to adverse outcomes in pregnancy
UCLA research deepens understanding of air pollution’s impact on placenta
UNIVERSITY OF CALIFORNIA - LOS ANGELES HEALTH SCIENCES
FINDINGS
A new study in mice by UCLA scientists reveals how exposure to traffic-related air pollutants causes cellular changes in the placenta that can lead to pregnancy complications and affect the health of both mother and offspring.
The researchers found that the cellular changes caused by chronic exposure to air pollutants were related to immune activation by foreign substances entering the blood from the lungs. This immune response attacks some of the placental cells that are required to maintain the placenta structurally, and most importantly, the blood flow from mother to developing baby.
BACKGROUND
Although previous research has analyzed the effect of air pollution on pregnancy, those studies did not utilize cell-specific methods or focus on molecular signatures of the placenta. This study is the first to assess how such exposure can negatively affect the placenta, leading to adverse outcomes in pregnancy.
METHOD
One group of female mice was exposed to environmental air pollutants nasally starting two months before conception and during pregnancy, while the control group of mice was exposed to saline. By the end of the study, tissue samples indicated that inhaled air pollutants had compromised the composition of the placental cells and molecular signatures. Researchers also identified inflammation in the mucosal lining of the uterus triggered by pollution.
IMPACT
The placenta is essential for a successful pregnancy and for maintaining the health of both the mother and the baby. These study findings suggest that maternal cells of immunity may be responsible for destruction of vital vascular cells in the placenta. This auto-destruction of placental structures can disrupt the maintenance of a healthy pregnancy or at least affect nutrient supply from the mother to the baby, with the potential for adverse pregnancy consequences or outcomes such as preterm labor or uteroplacental insufficiency as encountered in pre-eclampsia.
"The cellular changes we have observed could provide the missing link between exposure to air pollutants and adverse pregnancy outcomes, thereby helping to focus development of preventive strategies for at-risk pregnancies,” said Dr. Sherin Devaskar, lead author of the study and physician-in-chief of UCLA Mattel Children's Hospital and distinguished professor of pediatrics at the David Geffen School of Medicine at UCLA.
The research also underscores the need to examine the timing of exposure and whether acute v. chronic exposures have different effects. The authors also plan to study dietary interventions to alleviate distress on placental molecular signatures, nutrient supply and development.
AUTHORS
The collaborative study also involved Dr. Suhas G. Kallapur, chief of neonatology and developmental biology; Amit Ganguly, staff research associate; Shubhamoy Ghosh, PhD, assistant project scientist; Monica Cappelletti, PhD, adjunct assistant professor of pathology and laboratory medicine, all four in the department of Pediatrics-Neonatology at UCLA; Matteo Pellegrini, a professor of molecular, cell and developmental biology at UCLA and Anela Tosevska, PhD, bioinformatics scientist in the division of rheumatology, internal medicine at Medical University of Vienna, Austria.
IMAGE: THE PANAF CITIZEN SCIENCE PROJECT IS OPEN TO ANYONE WILLING TO TAKE PART IN ANNOTATING CAMERA TRAP VIDEOS FROM ACROSS TROPICAL AFRICAview more
CREDIT: MPI-EVA/PANAFCHIMP&SEE.ORG
Researchers reporting in the journal Cell Genomics on June 1 have produced the first catalogue of genomic diversity for endangered chimpanzees in the wild. The catalogue, which includes 828 chimp samples from across their range, offers a detailed reconstruction of chimp population structure and fine-scale patterns of isolation, migration, and connection. The researchers use this information to design a method to link confiscated chimpanzees to their place of origin within about 100 kilometers, with the goal to support efforts to combat the illegal trade of chimpanzees and related products.
“Chimpanzees are an endangered species with massive population declines in recent years,” said Claudia Fontsere, first author of the study at the Institute of Evolutionary Biology (IBE), a joint centre of CSIC and Universitat Pompeu Fabra (UPF) in Barcelona, Spain. “Our efforts to describe the current genomic diversity of this species are an attempt to provide a fine-scale map of connectivity between populations that can be of service to conservationists as a baseline and guide to build upon their conservation efforts.”
The effort would not have been possible without coordinated sampling of thousands of chimp fecal samples by the Pan African Program (PanAf) at 48 locations together with years of effort to develop methodological strategies to efficiently retrieve and enrich the proportion of host DNA in fecal samples, the researchers say. Fecal samples come with many technical challenges as they contain only small amounts of degraded chimpanzee DNA, but they also have advantages for the study of endangered species as they allow for extensive collection with minimal interference to the animals. These approaches can now be put to work to study many other endangered primates and other species.
“Since we are using sequencing of a whole chromosome with thousands of independent markers, compared to few microsatellite markers, we have a much broader view of the genome [that] is needed to refine and describe the very complex evolutionary history of chimpanzees,” adds Tomas Marques-Bonet, principal investigator from the Institute of Evolutionary Biology (IBE) and co-lead of the study. “Impressively, we are doing it with non-invasive samples, which, in a sense, are the best of all worlds—a valuable source of genomic DNA but collected in a way that animals never need to be contacted or disturbed beyond researchers existing in their habitat.”
Because the fossil record and ancient DNA for chimps is limited, the only way to reconstruct their past is through studies of living individuals. Scientists recognize four chimp subspecies, but questions had remained about their relationships. There have been long-standing questions about how connected those subspecies are and have been to each other.
To explore these questions in the new study, Fontsere and colleagues retrieved partial genome information from more than 800 non-invasively-collected wild chimpanzee fecal samples from across their current range. They focused their attention on chromosome 21, the smallest contiguous nuclear sequence in the chimpanzee genome and a source for a wealth of genomic sequence data for use in inferring chimpanzee population structure.
“Just by our sampling method, we have discovered around 50% more, and new, genetic variants on chromosome 21 than previous studies,” Fontsere said. “Our dataset has been key in understanding recent and past gene flow between populations where previous sampling gaps impeded their study. Also, it has allowed us to describe if populations have been isolated recently or whether there was a historical event that did so. By characterizing the genomic singularities of each community or population, we also created a map that links genomic information to geographic location so that we were able to devise a strategy to infer the geographic location of chimpanzee individuals.”
Previously, only 59 whole chimpanzee genomes had been sequenced with limited information on their origin, the researchers note. Large datasets from thousands of geo-referenced fecal samples also exist, but they represent only very small fragments of the entire genome. With these new samples and genomic data, they’ve been able to fill the previous gaps in the distribution of Eastern and Central chimpanzees.
CAPTION
Wild chimpanzee defecating
CREDIT
MPI-EVA/PanAf
Fontsere says they’ve also provided a more nuanced understanding of the genetic differentiation of the four recognized chimpanzee subspecies. They found a link between historical population structure, barriers of genetic continuity between chimpanzee populations, and geographical barriers such as rivers and lakes.
“We were able to show, using different analyses that look at very old and more recent variation, that the history of chimpanzees is complex, much like that of our own species,” says Mimi Arandjelovic, co-lead of the study from the Max Planck Institute for Evolutionary Anthropology, iDiv, and Leipzig University. “Chimpanzee subspecies were indeed separated in the past but have since also experienced genetic exchange between populations. This nicely explains why different studies aiming at reconstructing different ancestral periods have come to different conclusions about the evolutionary history of chimpanzees.”
Among many other insights, the evidence also reveals extensive connectivity in Western chimpanzees.
“This is so critically important to their conservation and really argues that connectivity between forests across Western Africa, especially in the northern region, needs to be preserved for the protection of these populations and the subspecies,” said Marques-Bonet.
The researchers say they are now beginning to use the methods they’ve developed for chimpanzees with other great apes and primates. Their findings in chimpanzees confirm that fecal samples, although more complex than blood samples, are a fine source of host DNA for any species.
The PanAf also continues to analyze data collected over 8 years from 18 countries across Africa, at over 40 temporary and long-term research and conservation sites. The goal is to understand the evolutionary and ecological drivers of chimpanzee cultural and behavioral diversity. Anyone interested can pitch in and help by annotating videos at the citizen science project https://www.zooniverse.org/projects/sassydumbledore/chimp-and-see.
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This work was supported by “La Caixa” Foundation, the Vienna Science and Technology Fund, the City of Vienna project, the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme, the “Unidad de Excelencia Maria de Maeztu” funded by the AEI, the Howard Hughes International Early Career award, the NIH, the Secretaria d’Universitats i Recerca and CERCA Programme del Departament d’Economia i Coneixement de la Generalitat de Catalunya, UCL’s Wellcome Trust, the Generalitat de Catalunya, and the Pan African Programme: The Cultured Chimpanzee (PanAf), funded by the Max Planck Society, the Max Planck Society Innovation Fund, and the Heinz L. Krekeler Foundation.
Cell Genomics (@CellGenomics) is a new gold open access journal from Cell Press publishing multidisciplinary research at the forefront of genetics and genomics. The journal aims to bring together diverse communities to advance genomics and its impact on biomedical science, precision medicine, and global and ecological health. Visit https://www.cell.com/cell-genomics/home. To receive Cell Press media alerts, please contact press@cell.com.
Population dynamics and genetic connectivity in recent chimpanzee history
ARTICLE PUBLICATION DATE
1-Jun-2022
New genomic tools shed light on the
evolutionary history of chimpanzees
and contribute to their conservation
An international research team led by the Institute of Evolutionary Biology (IBE) in Barcelona, the Max Planck Institute for Evolutionary Anthropology (MPI-EVA), the German Centre for Integrative Biodiversity Research (iDiv) and Leipzig University
Chimpanzees inhabit the tropical African savannah-woodlands and forests. In contrast to the hominid sites preserved to this day - mainly in caves and temperate climates - the areas that chimpanzees have inhabited have resulted in few specimens preserved or detected in the archaeological record. Given the absence of chimpanzee fossils, the genetic information from current populations is crucial for describing their evolutionary history, their genetic diversity and to contribute to their conservation.
An international research team led by the Institute of Evolutionary Biology (IBE), a joint centre of theCSIC and thePompeu Fabra University (UPF) in Barcelona, the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) and the German Centre for Integrative Biodiversity Research (iDiv) in Leipzig, has built the most extensive catalogue of genomic diversity in wild chimpanzee populations to date. Genetic information has been retrieved non-invasively using new technologies, from hundreds of chimpanzee faecal samples. For the first time, methods applied to analyse ancient DNA in human populations have been used to retrieve genetic information from great apes faecal samples. Further, the genomic database they have developed has direct applications for the conservation of chimpanzees, such as identifying illegal trafficking routes of wildlife products and orphans.
CAPTION
Photo composition of wild chimpanzees. Credit: MPI-EVA PanAf/ChimpandSee.org
CREDIT
MPI-EVA PanAf/ChimpandSee.org
The first genomic atlas for chimpanzees with non-invasive samples
The research team retrieved partial genome information from more than 800 chimpanzee faecal samples to create the largest and most detailed genomic diversity atlas of this African great ape.
“Using methods designed to study ancient DNA, as in the case of Neanderthals, we have been able to retrieve genomic information from faecal samples, which are very difficult to work with. We have applied that approach to an unprecedented number of chimpanzee samples from the field”, points out Prof. Tomàs Marquès-Bonet, principal investigator of the Institute of Evolutionary Biology (IBE) and co-lead of the study.
Collecting geo-referenced non-invasive samples from nature is an effective way to obtain genomic information from wild chimpanzees when many factors limit the collection of high-quality samples, such as blood or tissues.
“We have seen that faecal samples, while imposing technical difficulties, provide very valuable genomic information for the study of wild chimpanzee populations, and also allow us the possibility to geo-reference them and track contacts between populations without affecting their well-being”, adds Dr. Clàudia Fontserè, researcher atIBE Comparative Genomics group and first author of the study.
Reconstructing the evolutionary history of chimpanzees to promote their conservation
With this extensive data set, authors shed light on the demographic past of chimpanzees and provide further evidence of the genetic differentiation of, and exchanges between, the four recognized subspecies.
The research team identified that geographical features, such as rivers, constitute permeable barriers to gene flow between chimpanzee subspecies, but also between communities. In addition, researchers proposed patterns of migration, connectivity, and isolation between groups of chimpanzees that have shaped the variation in the genomic landscape of these populations over the past 100,000 years.
“We've noticed that sometimes, even though two communities are geographically very close, they may live on two different sides of a river and have only had very limited and sporadic contact. Our approach is very helpful in identifying barriers and natural corridors between populations and may have implications for their conservation”, says Fontserè.
"Chimpanzees, like humans, have had a complex evolutionary history. Their dynamics and areas of past and current population contact must be clearly identified in order to contribute to the protection of this endangered species", points out Dr. Mimi Arandjelovic, co-lead of the study and researcher at the Max Planck Institute for Evolutionary Anthropology, iDiv and Leipzig University. Dr. Arandjelovic is co-director of the Pan African Programme: The Cultured Chimpanzee (PanAf), a consortium of researchers and conservationists from Africa, Europe and North America who spent 8 years collecting behavioural, ecological and organic data from across the entire chimpanzee range.
Genomics to fight chimpanzee illegal trafficking
The new genomic tool has allowed the team to reliably identify from where individuals originate, a task not feasible until now. The ability to accurately determine the origin of chimpanzees has direct applications for their conservation, such as detecting the places where their poaching might be concentrated and identifying the routes and origins of illegal chimpanzee trafficking. “The tool developed can infer the origin of the confiscated chimpanzees, usually at a few hundred kilometres from the real origin, and thus provide reliable information on the priority regions to be protected,” adds Marquès-Bonet. The developed methodology is already being applied in global conservation projects for the other great apes, bonobos, orangutans and gorillas, as part of collaboration with the Illumina iConserve program and currently being sequenced at the CNAG-CRG in Barcelona.
This study is part of the PanAf, hosted at the Max Planck Institute for Evolutionary Anthropology and the German Centre for Integrative Biodiversity Research (iDiv) in Leipzig, as well as the European ERC Consolidator grant ApeGenomeDiversity, awarded to Tomàs Marquès-Bonet.
ITHACA, N.Y. – More than 99% of veterinarians surveyed said they’d encountered useless or non-beneficial veterinary care in their careers, according to a new Cornell-led study that documents the prevalence of futile care for the first time. The authors use a working definition of futile care as continuing treatment when relevant goals can no longer be reached.
“Before Cornell, I was in private practice in Los Angeles for 11 years. When faced with a dilemma like this, I had an obligation to advocate for what I thought was in the best interest of the pet,” said Dr. Nathan Peterson, associate clinical professor with the section of emergency and critical care and lead author of the study.
“But I also had an obligation to the owner,” Peterson said. “I couldn’t just do what I thought was right. It’s really quite distressing for the veterinarian and for the technicians and nurses who have to carry out the care.”
The study, co-authored by researchers at Harvard Medical School’s Center for Bioethics, also found that 89% of veterinarians said they had administered futile care, and 42% said it occurs frequently, more than six times per year.
The owner-centered approach, the authors write, can exacerbate moral distress for veterinarians and care teams. Previous research by co-authors showed that futile veterinary care was responsible for frequent and severe moral distress in the veterinary community, which they said occurs when a clinician believes they know the right thing to do but are prevented from doing it.
“We’re in the midst of a mental health crisis in our profession, and we’re very interested in whether futile care contributes to that, which I suspect it does,” Peterson said. “We felt that a first step is documenting that it happens. My hope for the research is that it opens conversations around futile care, and hopefully professional organizations can take a leadership role and try to provide some guidance for how to resolve these conflicts.”
The authors suggest establishing a definition for futile care in the profession – respondents were not in total consensus about what futile care means – as well as guidance around how decisions for care are made.
“I think as a profession we have focused for so long on alleviating suffering by continuing treatment and making animals healthier,” Peterson said. “And we’re not as prepared to strongly advocate for euthanasia, to have those conversations, even when we think that’s the best way to alleviate suffering.”
In future research, Peterson hopes to investigate the impact of futile care on support staff. “That feeling of powerlessness for the veterinarian is certainly magnified for the technicians who are often not involved in the decisions and who are directly responsible for providing care,” he said.
New research led by scientists at the Milner Centre for Evolution at the University of Bath suggests that determining evolutionary trees of organisms by comparing anatomy rather than gene sequences is misleading. The study, published in Communications Biology, shows that we often need to overturn centuries of scholarly work that classified living things according to how they look.
Since Darwin and his contemporaries in the 19th Century, biologists have been trying to reconstruct the “family trees” of animals by carefully examining differences in their anatomy and structure (morphology).
However, with the development of rapid genetic sequencing techniques, biologists are now able to use genetic (molecular) data to help piece together evolutionary relationships for species very quickly and cheaply, often proving that organisms we once thought were closely related actually belong in completely different branches of the tree.
For the first time, scientists at Bath compared evolutionary trees based on morphology with those based on molecular data, and mapped them according to geographical location.
They found that the animals grouped together by molecular trees lived more closely together geographically than the animals grouped using the morphological trees.
Matthew Wills, Professor of Evolutionary Paleobiology at the Milner Centre for Evolution at the University of Bath, said: “It turns out that we’ve got lots of our evolutionary trees wrong.
“For over a hundred years, we’ve been classifying organisms according to how they look and are put together anatomically, but molecular data often tells us a rather different story.
“Our study proves statistically that if you build an evolutionary tree of animals based on their molecular data, it often fits much better with their geographical distribution.
“Where things live – their biogeography – is an important source of evolutionary evidence that was familiar to Darwin and his contemporaries.
“For example, tiny elephant shrews, aardvarks, elephants, golden moles and swimming manatees have all come from the same big branch of mammal evolution - despite the fact that they look completely different from one another (and live in very different ways).
“Molecular trees have put them all together in a group called Afrotheria, so-called because they all come from the African continent, so the group matches the biogeography.”
The study found that convergent evolution – when a characteristic evolves separately in two genetically unrelated groups of organisms – is much more common than biologists previously thought.
Professor Wills said: “We already have lots of famous examples of convergent evolution, such as flight evolving separately in birds, bats and insects, or complex camera eyes evolving separately in squid and humans.
“But now with molecular data, we can see that convergent evolution happens all the time – things we thought were closely related often turn out to be far apart on the tree of life.
“People who make a living as lookalikes aren’t usually related to the celebrity they’re impersonating, and individuals within a family don’t always look similar - it’s the same with evolutionary trees too.
“It proves that evolution just keeps on re-inventing things, coming up with a similar solution each time the problem is encountered in a different branch of the evolutionary tree.
“It means that convergent evolution has been fooling us - even the cleverest evolutionary biologists and anatomists - for over 100 years!”
Dr Jack Oyston, Research Associate and first author of the paper, said: “The idea that biogeography can reflect evolutionary history was a large part of what prompted Darwin to develop his theory of evolution through natural selection, so it's pretty surprising that it hadn't really been considered directly as a way of testing the accuracy of evolutionary trees in this way before now.
“What's most exciting is that we find strong statistical proof of molecular trees fitting better not just in groups like Afrotheria, but across the tree of life in birds, reptiles, insects and plants too.
“It being such a widespread pattern makes it much more potentially useful as a general test of different evolutionary trees, but it also shows just how pervasive convergent evolution has been when it comes to misleading us.”
IMAGE: TIME SEQUENCE SHOWING DETAILS OF A CORK EXPELLED FROM A CHAMPAGNE BOTTLENECK STORED AT 20 DEGREES CELSIUS CAPTURED THROUGH HIGH-SPEED IMAGING.view more
CREDIT: GÉRARD LIGER-BELAIR
WASHINGTON, June 1, 2022 – Opening a bottle of champagne traditionally marks the beginning of a festive celebration. Following the fun pop of the cork, a fizz of bubbles releases into the air, and finally, there is the pleasant tingle on the tongue.
But there is much more that comes out of the pop than meets the senses, according to researchers in France and India. In Physics of Fluids, by AIP Publishing, computational fluid dynamics simulations revealed the formation, evolution, and dissipation of shock wave patterns as the carbon dioxide mixture shoots through the bottleneck in the first millisecond after cork popping.
The findings could provide insight into the complex and transient behavior of supersonic flow in applications ranging from rocket launchers, ballistic missiles, and wind turbines to electronics manufacturing and underwater vehicles. The simulations build on experimental research in 2019 that showed, for the first time, the formation of shock waves during cork popping.
"We wanted to better characterize the unexpected phenomenon of a supersonic flow that takes place during champagne bottle uncorking," said co-author Robert Georges, from the Université de Rennes 1. "We hope our simulations will offer some interesting leads to researchers, and they might consider the typical bottle of champagne as a mini-laboratory."
In the initial uncorking phase, the gas mixture is partially blocked by the cork, preventing the ejecting champagne from reaching the speed of sound. But as the cork further releases, the gas mixture escapes radially at supersonic speed, balancing its pressure through a succession of normal and oblique shock waves.
The waves combine to form shock diamonds, patterns of rings typically seen in rocket exhaust plumes. The bottle symmetry leads to a crown-shaped supersonic expansion. Eventually, the pressure becomes too low to maintain an appropriate nozzle pressure ratio for supersonic speed at the bottleneck and cork's edge.
"Our paper unravels the unexpected and beautiful flow patterns that are hidden right under our nose each time a bottle of bubbly is uncorked," said co-author Gérard Liger-Belair, from Université de Reims Champagne-Ardenne. "Who could have imagined the complex and aesthetic phenomena hidden behind such a common situation experienced by any one of us?"
The researchers plan to explore other parameters, such as temperature, volume, and bottleneck diameter, along with the physicochemical processes that accompany champagne bottle uncorking. For instance, they are interested in how supersonic flow is affected by ice particle formation caused by the drastic temperature drop as the fizz ejects from the bottle.
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The article "Computational Fluid Dynamic simulation of the supersonic CO2 flow during champagne cork popping" is authored by Abdessamad Benidar, Robert Georges, Vinayak Kulkarni, Daniel Cordier, and Gérard Liger-Belair. The article appears in Physics of Fluids (DOI: 10.1063/5.0089774 and can be accessed at https://aip.scitation.org/doi/full/10.1063/5.0089774.
ABOUT THE JOURNAL
Physics of Fluids is devoted to the publication of original theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and complex fluids. See https://aip.scitation.org/journal/phf.
NIH/NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
IMAGE: TRANSMISSION ELECTRON MICROSCOPE IMAGE OF SARS-COV-2 VIRUS PARTICLES EMERGING FROM THE SURFACE OF A CELL CULTURED IN THE LAB. IMAGE CAPTURED AND COLORIZED AT ROCKY MOUNTAIN LABORATORIES IN HAMILTON, MONTANA.view more
CREDIT: NIAID
A National Institutes of Health-funded study has found that people with food allergies are less likely to become infected with SARS-CoV-2, the virus that causes COVID-19, than people without them. In addition, while previous research identified obesity as a risk factor for severe COVID-19, the new study has identified obesity and high body mass index (BMI) as associated with increased risk for SARS-CoV-2 infection. In contrast, the study determined that asthma does not increase risk for SARS-CoV-2 infection.
The Human Epidemiology and Response to SARS-CoV-2 (HEROS) study also found that children ages 12 years or younger are just as likely to become infected with the virus as teenagers and adults, but 75% of infections in children are asymptomatic. In addition, the study confirmed that SARS-CoV-2 transmission within households with children is high. These findings were published today in the Journal of Allergy and Clinical Immunology.
“The HEROS study findings underscore the importance of vaccinating children and implementing other public health measures to prevent them from becoming infected with SARS-CoV-2, thus protecting both children and vulnerable members of their household from the virus,” said Anthony S. Fauci, M.D., director of the National Institute of Allergy, and Infectious Diseases (NIAID), part of NIH. “Furthermore, the observed association between food allergy and the risk of infection with SARS-CoV-2, as well as between body-mass index and this risk, merit further investigation.” NIAID sponsored and funded the HEROS study.
Tina V. Hartert, M.D., M.P.H, co-led the research with Max A. Seibold, Ph.D. Dr. Hartert is director of the Center for Asthma and Environmental Sciences Research, vice president for translational science, the Lulu H. Owen Chair in Medicine, and a professor of medicine and pediatrics at the Vanderbilt University School of Medicine in Nashville. Dr. Seibold is director of computational biology, the Wohlberg and Lambert Endowed Chair of Pharmacogenomics, and a professor of pediatrics in the Center for Genes, Environment, and Health at National Jewish Health in Denver.
The HEROS study team monitored for SARS-CoV-2 infection in more than 4,000 people in nearly 1,400 households that included at least one person age 21 years or younger. This surveillance took place in 12 U.S. cities between May 2020 and February 2021, before the widespread rollout of COVID-19 vaccines among non-healthcare workers in the United States and before the widespread emergence of variants of concern. Participants were recruited from existing, NIH-funded studies focused on allergic diseases. Roughly half of the participating children, teenagers and adults had self-reported food allergy, asthma, eczema, or allergic rhinitis.
A caregiver in each household took nasal swabs of participants every two weeks to test for SARS-CoV-2 and filled out weekly surveys. If a member of the household developed symptoms consistent with COVID-19, additional nasal swabs were taken. Blood samples also were collected periodically and after a family’s first reported illness, if there was one.
When the HEROS study began, preliminary evidence from other research suggested that having an allergic disease might reduce a person’s susceptibility to SARS-CoV-2 infection. The HEROS investigators found that having self-reported, physician-diagnosed food allergy cut the risk of infection in half, but asthma and the other allergic conditions monitored—eczema and allergic rhinitis—were not associated with reduced infection risk. However, the participants who reported having food allergy were allergic to three times as many allergens as the participants who did not report having food allergy.
Since all these conditions were self-reported, the HEROS study team analyzed the levels of immunoglobulin E (IgE)-specific antibodies, which play a key role in allergic disease, in blood collected from a subset of participants. A correspondence between self-reported food allergy and food allergen-specific IgE measurements supports the accuracy of self-reported food allergy among HEROS participants, according to the investigators.
Dr. Hartert and colleagues speculate that type 2 inflammation, a characteristic of allergic conditions, may reduce levels of a protein called the ACE2 receptor on the surface of airway cells. SARS-CoV-2 uses this receptor to enter cells, so its scarcity could limit the virus’s ability to infect them. Differences in risk behaviors among people with food allergy, such as eating out at restaurants less often, also could explain the lower infection risk for this group. However, through biweekly assessments, the study team found that households with food-allergic participants had only slightly lower levels of community exposure than other households.
Previous studies have shown that obesity is a risk factor for severe COVID-19. In the HEROS study, investigators found a strong, linear relationship between BMI―a measure of body fat based on height and weight―and the risk of SARS-CoV-2 infection. Every 10-point increase in BMI percentile raised the risk of infection by 9%. Participants who were overweight or obese had a 41% greater risk of infection than those who were not. More research is needed to explain these findings. In this regard, planned analyses of gene expression in cells collected from nasal swabs of participants before and after SARS-CoV-2 infection may provide clues about the inflammatory environment associated with infection, which may change as BMI increases, according to the investigators.
The HEROS researchers found that children, teenagers and adults in the study all had around a 14% chance of SARS-CoV-2 infection during the six-month surveillance period. Infections were asymptomatic in 75% of children, 59% of teenagers and 38% of adults. In 58% of participating households where one person became infected, SARS-CoV-2 was transmitted to multiple household members.
The amount of SARS-CoV-2 found in nasal swabs, that is, the viral load, varied widely among study participants in all age groups. The viral load range among infected children was comparable to that of teenagers and adults. Given the rate of asymptomatic infection in children, a larger proportion of infected children with high viral loads may be asymptomatic compared to infected adults with high viral loads.
The HEROS investigators concluded that young children may be very efficient SARS-CoV-2 transmitters within the household due to their high rate of asymptomatic infection, their potentially high viral loads, and their close physical interactions with family members.
Reference: MA Seibold et al. Risk factors for SARS-CoV-2 infection and transmission in households with asthmatic and allergic children. A prospective surveillance study. Journal of Allergy and Clinical Immunology DOI: 10.1016/j.jaci.2022.05.014 (2022).
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