March for Science ATL: photos

Emory scientists and supporters of science were out in substantial numbers Saturday at the March for Science Atlanta in Candler Park. March organizers, many of whom came from the Emory research community, say they want to continue their advocacy momentum and community-building after the event’s Read more

How race + TBI experience affect views of informed consent

The upcoming HBO movie of The Immortal Life of Henrietta Lacks reminds us that biomedical research has a complex legacy, when it comes to informed consent and people of color. A paper from Emory investigators touches on related issues important for conduct of clinical research Read more

Fecal transplant replants microbial garden

Emory physicians explain how FMT (fecal microbiota transplant) restores microbial balance when someone’s internal garden has been Read more

Department of Pediatrics

Excellent exosomes harvest cardiac regenerative capacity

Thanks to biomedical engineer Mike Davis for writing an explanation of “Exosomes: what do we love so much about them?” for Circulation Research, a companion to his lab’s November 2016 publication analyzing exosomes secreted by human cardiac progenitor cells.

We can think of exosomes as tiny packages that cells send each other. They’re secreted bubbles containing proteins and regulatory RNAs. Thus, they may be a way to harvest the regenerative capacity of pediatric heart tissue without delivering the cells themselves.

Mike Davis, PhD is director of the Children’s Heart Research and Outcomes Center (HeRO), part of the Emory/Children’s/Georgia Tech Pediatric Research Alliance

Davis’ lab studied cardiac tissue derived from children of different ages undergoing surgery for congenital heart defects. The scientists isolated exosomes from the cardiac progenitor cells, and tested their regenerative activity in rats with injured hearts.

They found that exosomes derived from older children’s cells were only reparative if they were subjected to hypoxic conditions (lack of oxygen), while exosomes from newborns’  cells improved rats’  cardiac function with or without hypoxia. Read more

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Zika virus blindfolds immune alarm cells

Important immune alarm cells — dendritic cells — are fighting Zika virus with an arm tied behind their backs, scientists from Emory Vaccine Center report.

Dendritic cells are “sentinel” cells that alert the rest of the immune system when they detect viral infection. When Zika virus infects them, it shuts down interferon signaling, one route for mustering the antiviral troops. However, another antiviral pathway called RIG-I-like receptor (RLR) signaling is left intact and could be a target for immunity-boosting therapies, the researchers say.

Mehul Suthar, PhD in the lab with graduate students Kendra Quicke and James Bowen

The findings were published on Feb. 2 in PLOS Pathogens.

Zika was known to disrupt interferon signaling, but Emory researchers have observed that it does so in ways that are distinct from other related flaviviruses, such as Dengue virus and West Nile virus. The findings give additional insight into how Zika virus is able to counter human immune defenses. Read more

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Case report on first newborn to survive Ebola

Pediatric infectious diseases specialist Anita McElroy was a co-author on a case report on the first newborn to survive Ebola infection, published recently in Journal of Infectious Diseases.

“Of all the work I’ve been privileged to be involved in over the past few years, this paper was one of the most personally satisfying,” McElroy writes.

The child described in the paper is named Nubia; she is mentioned in several news stories from 2015. She was the last known Ebola case in Guinea, one of three African countries hit hard by the virus in 2014 and 2015. Her mother died shortly after her birth.

Nubia leaves hospital in Guinea. Photo from Medecins Sans Frontieres.

Nubia was cared for at the Ebola treatment ward run by Medecins Sans Frontieres (MSF, aka Doctors without Borders) in Conakry, Guinea. She was given three experimental therapies: ZMapp antibodies, survivor white blood cell transfusion and an antiviral drug called GS-5734. It is not clear which of these interventions were critical for Nubia’s recovery, although the paper makes clear that ZMapp did not result in viral suppression all by itself.

McElroy is a go-to person for studies of dangerous viruses such as Ebola, Lassa and Zika, partly because of her affiliation with the Centers for Disease Control and Prevention’s Viral Special Pathogens Branch. She advised the MSF team on the use of the antiviral drug and other interventions.

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Double vision: seeing viruses by both light and electron microscopy

Advances in both light and electron microscopy are improving scientists’ ability to visualize viruses such as HIV, respiratory syncytial virus (RSV), measles, influenza, and Zika in their native states.

Researchers from Emory University School of Medicine and Children’s Healthcare of Atlanta developed workflows for cryo-correlative light and electron microscopy (cryo-CLEM), which were published in the January 2017 issue of Nature Protocols.

An example of the images of viruses obtainable with cryo-CLEM. Pseudotyped HIV-1 particles undergoing endocytosis. Viral membrane = light blue. Mature core = yellow. Clathrin cages = purple. From Hampton et al Nat. Protocols (2016)

Previously, many electron microscopy images of well-known viruses were obtained by studying purified virus preparations. Yet the process of purification can distort the structure of enveloped viruses, says Elizabeth R. Wright, PhD, associate professor of pediatrics at Emory University School of Medicine.

Wright and her colleagues have refined techniques for studying viruses in the context of the cells they infect. That way, they can see in detail how viruses enter and are assembled in cells, or how genetic modifications alter viral structures or processing.

“Much of what is known about how some viruses replicate in cells is really a black box at the ultrastructural level,” she says. “We see ourselves as forming bridges between light and electron microscopy, and opening up new realms of biological questions.”

Wright is director of Emory’s Robert P. Apkarian Integrated Electron Microscopy Core and a Georgia Research Alliance Distinguished Investigator. The co-first authors of the Nature Protocols paper are postdoctoral fellows Cheri Hampton, PhD. and Joshua Strauss, PhD, and graduate students Zunlong Ke and Rebecca Dillard.

The Wright lab’s work on cryo-CLEM includes collaborations with Gregory Melikyan in Emory’s Department of Pediatrics, Phil Santangelo in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, and Paul Spearman, now at Cincinnati Children’s.

For this technique, virus-infected or transfected cells are grown on fragile carbon-coated gold grids and then “vitrified,” meaning that they are cooled rapidly so that ice crystals do not form. Once cooled, the cells are examined by cryo-fluorescent light microscopy and cryo-electron tomography. Read more

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Threading the RSV needle: live attenuated vaccine effective in animals

Crafting a vaccine against RSV (respiratory syncytial virus) has been a minefield for 50 years, but scientists believe they have found the right balance.

A 3-D rendering of a live-attenuated respiratory syncytial virus (RSV) particle, captured in a near-to-native state by cryo-electron tomography. Surface glycoproteins (yellow) are anchored on the viral membrane (cyan), with ribonucleoprotein complexes inside (red). Image courtesy of Zunlong Ke and Elizabeth Wright.

Researchers at Emory University School of Medicine and Children’s Healthcare of Atlanta have engineered a version of RSV that is highly attenuated – weakened in its ability to cause disease – yet potent in its ability to induce protective antibodies.

The researchers examined the engineered virus using cryo-electron microscopy and cryo-electron tomography techniques, and showed that it is structurally very similar to wild type virus. When used as a vaccine, it can protect mice and cotton rats from RSV infection.

The results were published this morning in Nature Communications.

“Our paper shows that it’s possible to attenuate RSV without losing any immunogenicity,” says senior author Martin Moore, PhD, associate professor of pediatrics at Emory University School of Medicine and a Children’s Healthcare of Atlanta Research Scholar. “This is a promising live-attenuated vaccine candidate that merits further investigation clinically.”

The next steps for this vaccine are to produce a clinical grade lot and conduct a phase 1 study of safety and immunogenicity in infants, Moore says. Read more

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Bad neighbors cause bad blood -> cancer

Certain DNA mutations in bone cells that support blood development can drive leukemia formation in nearby blood stem cells, cancer researchers have found.

Many cancer-driving mutations are “cell-autonomous,” meaning the change in a cell’s DNA makes that same cell grow more rapidly. In contrast, an indirect neighbor cell effect was observed in a mouse model of Noonan syndrome, an inherited disorder that increases the risk of developing leukemia.

bone-marrow-300

In mouse bone marrow, mesenchymal stem cells (red), which normally nurture blood stem cells, produce a signal that is attractive for monocytes. The monocytes (green) prod nearby blood stem cells to proliferate, leading to leukemia. From Dong et al Nature (2016).

The findings were published Wednesday, October 26 in Nature.

The neighbor cell effect could be frustrating efforts to treat leukemias in patients with Noonan syndrome and a related condition, juvenile myelomonocytic leukemia (JMML). That’s because bone marrow transplant may remove the cancerous cells, but not the cause of the problem, leading to disease recurrence. However, the researchers show that a class of drugs can dampen the cancer-driving neighbor effect in mice. One of the drugs, maraviroc, is already FDA-approved against HIV infection.

“Our research highlights the importance of the bone marrow microenvironment,” says Cheng-Kui Qu, MD, PhD, professor of pediatrics at Emory University School of Medicine, Winship Cancer Institute and Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta. “We found that a disease-associated mutation, which disturbs the niches where blood stem cell development occurs, can lead to leukemia formation.”

Editorial note: This Nature News + Views, aptly titled “Bad neighbors cause bad blood,” explains JMML, and how the relapse rate after bone marrow transplant is high (about 50 percent). It also notes that a variety of genetic alterations provoke leukemia when engineered into bone marrow stromal cells in mice (like this), but Qu and his colleagues described one that is associated with a known human disease.

Noonan syndrome often involves short stature, distinctive facial features, congenital heart defects and bleeding problems. It occurs in between one in 1000 to one in 2500 people, and can be caused by mutations in several genes. The most common cause is mutations in the gene PTPN11. Children with Noonan syndrome are estimated to have a risk of developing leukemia or other cancers that is eight times higher than their peers.
Read more

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Dengue infection makes exhausted T cells?

An ongoing collaboration between the Emory Vaccine Center and the ICGEB (International Centre for Genetic Engineering and Biotechnology) in New Delh, investigating immune responses to dengue virus, is getting some attention.

A Journal of Virology paper published by the collaboration was highlighted by Nature Asia. In that paper, the researchers show that in dengue infection, the group of antiviral immune cells known as CD8+ T cells undergoes a massive expansion. That could be dangerous if all of the CD8 T cells were making inflammatory cytokines, but they do not. Only a small fraction are making cytokines.

The authors point out that this phenomenon is “somewhat reminiscent of T-cell exhaustion seen under the conditions of prolonged antigenic stimulus in chronic viral infections [which has been studied in detail by Rafi Ahmed and colleagues] or closely resembles the ‘stunned’ phenotype reported in febrile phase of other acute infections such as HIV and viral hepatitis… The IFN-γ unresponsiveness acquired during the massive antigen-driven clonal expansion is likely to ensure that these cells do not cause excessive inflammation at the time that their numbers are high during the febrile phase of dengue disease.” Read more

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Let’s not elope

Elopement may sound cute, because the word evokes a starry-eyed couple running away to get married. Elopement also refers to when a child runs or wanders from a safe, supervised environment. It can be a worrisome concern among the parents and caregivers of children with autism spectrum disorder and/or intellectual disability.

Here is a straightforward post from Seattle Children’s on elopement. Cathy Rice, now director of Emory Autism Center and previously at the CDC, has published two papers on elopement.

This May, Nathan Call, director of Severe Behavior Programs at Marcus Autism Center, and colleagues published a retrospective review of their behavioral treatments for elopement, extending back to 2003. This is a companion to their 2015 analysis of treatment for pica, the ingestion of inedible substances. Call is also assistant professor of pediatrics at Emory University School of Medicine.

He summarized their approach by saying: “Individualizing treatment based upon the reason each child elopes seems to work very well.” The paper makes it clear that the reasons for a child eloping were a mixed bag: for some it was “access to preferred tangible items,” for others it was access to attention or other reasons.

Elopement can be difficult to study scientifically because the consequences of just letting it happen may be disastrous. In an interview, Call described one child who was attracted by balloons. He eloped so readily that he had been struck by cars twice, one time because he was drawn to a balloon display at a nearby apartment complex.

The 11 children in the review were ages 5 to 12, and 7 had a diagnosis of autism spectrum disorder – others had Down syndrome or intellectual disability. Read more

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Tapping evolution to improve biotech products

Scientists can improve protein-based drugs by reaching into the evolutionary past, a paper published this week in Nature Biotechnology proposes.

As a proof of concept for this approach, the research team from Emory, Children’s Healthcare of Atlanta and Georgia Tech showed how “ancestral sequence reconstruction” or ASR can guide engineering of the blood clotting protein known as factor VIII, which is deficient in the inherited disorder hemophilia A.

fviii_2r7e

Structure of Factor VIII

Other common protein-based drugs include monoclonal antibodies, insulin, human growth hormone and white blood cell stimulating factors given to cancer patients. The authors say that ASR-based engineering could be applied to other recombinant proteins produced outside the human body, as well as gene therapy.

It has been possible to produce human factor VIII in recombinant form since the early 1990s. However, current factor VIII products still have problems: they don’t last long in the blood, they frequently stimulate immune responses in the recipient, and they are difficult and costly to manufacture.

Experimental hematologist and gene therapist Chris Doering, PhD and his colleagues already had some success in addressing these challenges by filling in some of the sequence of human factor VIII with the same protein from pigs.

“We hypothesized that human factor VIII has evolved to be short lived in the blood to reduce the risk of thrombosis,” Doering says. “And we reasoned that by going even farther back in evolutionary history, it should be possible to find more stable, potent relatives.”

Doering is associate professor of pediatrics at Emory University School of Medicine and Aflac Cancer and Blood Disorders Center of Children’s Healthcare of Atlanta. The first author of the paper is former Molecular and Systems Pharmacology graduate student Philip Zakas, PhD.

Doering’s lab teamed up with Trent Spencer, PhD, director of cell and gene therapy for the Aflac Cancer and Blood Disorders Center, and Eric Gaucher, PhD, associate professor of biological sciences at Georgia Tech, who specializes in ASR. (Gaucher has also worked with Emory biochemist Eric Ortlund – related item on ASR from Gaucher)

ASR involves reaping the recent harvest of genome sequences from animals as varied as mice, cows, goats, whales, dogs, cats, horses, bats and elephants. Using this information, scientists reconstruct a plausible ancestral sequence for a protein in early mammals. They then tweak the human protein, one amino acid building block at a time, toward the ancestral sequence to see what kinds of effects the changes could have. Read more

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Vaccine vs many common cold viruses achievable

Scientists are making the case that a vaccine against rhinoviruses, the predominant cause of the common cold, is achievable.

The quest for a vaccine against rhinoviruses may have seemed quixotic, because there are more than 100 varieties circulating around the world. Even so, the immune system can handle the challenge, researchers from Emory University School of Medicine and Children’s Healthcare of Atlanta say.

Martin Moore, PhD

Martin Moore, PhD

Vaccines that combine dozens of varieties of rhinovirus at once are effective in stimulating antiviral antibodies in mice and monkeys, the researchers report in Nature Communications. The paper was also posted on Biorxiv before publication.

“We think that creating a vaccine for the common cold can be reduced to technical challenges related to manufacturing,” says Martin Moore, PhD, associate professor of pediatrics at Emory University School of Medicine and Children’s Healthcare of Atlanta. Read more

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