Zika virus can infect and replicate in immune cells from the placenta, without killing them, scientists have discovered. The finding may explain how the virus can pass through the placenta of a pregnant woman, on its way to infect developing brain cells in her fetus.
Infected placental macrophages. Zika antigens visible in red. From Quicke et al (2016).
“Our results substantiate the limited evidence from pathology case reports,” says senior author Mehul Suthar, PhD, assistant professor of pediatrics at Emory University School of Medicine. “It was known that the virus was getting into the placenta. But little was known about where the virus was replicating and in what cell type.”
Scientists led by Suthar and Emory pediatric infectious disease specialist Rana Chakraborty, MD, found that Zika virus could infect placental macrophages, called Hofbauer cells, in cell culture. The virus could also infect another type of placental cell, called cytotrophoblasts, but only after a couple days delay and not as readily. Other researchers recently reported that syncytiotrophoblasts, a more differentiated type of placental cell than cytotrophoblasts, are resistant to Zika infection.
The cells for the experiments were derived from full-term placentae, obtained from healthy volunteers who delivered by Cesarean section. The level of viral replication varied markedly from donor to donor, which hints that some women’s placentae may be more susceptible to viral infection than others. Read more
Third in a series on malaria immunology from graduate student Taryn McLaughlin. Sorry for the delay last week, caused by technical blog glitches.
It’s easy for me to find reasons to brag when it comes to research here at Emory. However, even an unbiased person should be excited about the malaria vaccine platform being developed by Alberto Moreno at the Emory Vaccine Center.
His vaccine is based on a chimeric protein (a protein that is a combination of bits and pieces of multiple proteins, a la the creature from Greek mythology) that should get your immune system to target multiple stages of the Plasmodium vivax life cycle. Part of it targets the infectious sporozoite, part of it targets the blood stage merozoite, and part of it will even target the transmitted gamete in future versions. This seems like a no brainer. Of course we should be targeting multiple stages! Read more
Continuing from Monday’s post, IMP graduate student Taryn McLaughlin explains why the most advanced malaria vaccine is actually not that great.
Malaria has plagued humans for thousands of years. And while we have known the causative agents of the disease- for 150 years, malaria remains scientifically frustrating. In fact, one of the most common treatments for the disease is simply a derivative of a treatment used in ancient China.
One of the most frustrating features is that there is no sterilizing immunity. In other words, for many diseases once you are infected with the microbe responsible, you develop an immune response and then never get the disease again. Not so with malaria. Compounded with terrible treatment and the impracticality of ridding the world of mosquitos, a vaccine sounds like pretty much our only hope. And yet this has been scientifically challenging and unsuccessful for many many reasons.
As a quick refresher, Plasmodium enters the body via mosquitos as a sporozoite. It then migrates through the skin going into the blood and eventually making itâ€™s way to the liver. Here it goes inside liver cells where it replicates and turns into merozoites (such that one sporozoite becomes thousands of merozoites). This stage of the disease is asymptomatic. Some time later, all those merozoites burst out of your liver cells causing mayhem and invading your red blood cells. Here, they once again replicate and metamorphose. Fun times. Anyways, during the last stage, some of those plasmodium become gametes which get eaten by mosquitos thus completing the life cycle.Read more
Those of us in the US are fortunate to not have to consider malaria in our day-to-day lives. Globally though, malaria is a serious public health threat with nearly 3.2 billion people at risk and close to half a million deaths every year. The scientific community has been developing malaria vaccines for decades. Yet a robust vaccine still remains elusive. Why?
IMP graduate student Taryn McLaughlin
One set of barriers comes from economics:Â malariaâ€™s strongest impact is in developing countries. But there is just as strong a case to be made for scientific obstacles. Frankly, the parasite (technically a bunch of species of microbes that I’ll just lump together under the umbrella term Plasmodium) that causes malaria is just smarter than we are.
I’m only kidding, but it is a fascinating organism. Its complexity makes it difficult to pin down and also interesting to write about. But before we talk about why Plasmodium is such a pain, let’s first discuss what exactly makes an effective vaccine.Read more
To prevent auto-immune attack, our bodies avoid making antibodies against molecules found on our own cells. That leaves gaps in our immune defenses bacteria could exploit. Some of those gaps are filled by galectins, a family of proteins whose anti-bacterial properties were identified by Emory scientists.
In the accompanying video, Sean Stowell, MD, PhD and colleagues explain how galectins can be compared to sheep dogs, which are vigilant in protecting our cells (sheep) against bacteria that may try to disguise themselves (wolves).
The video was produced to showcase the breadth of research being conducted within Emoryâ€™s Antibiotic Resistance Center. Because of their ability to selectively target some kinds of bacteria, galectins could potentially be used as antibiotics to treat infections without wiping out all the bacteria in the body. Read more
Emory rheumatologist Arezou Khosroshahi was the lead author on a differential diagnosisÂ case report in New England Journal of MedicineÂ published in October, which describesÂ an example of IgG4-related disease. This autoimmune conditionâ€™s name was agreed upon only recently, at an international conference she co-directed in 2011.
This review calls IgG4-related disease an â€œorphan disease with many faces.â€Â It sounds like each case has the potential to be an episode of House. As Khosroshahi explains:
â€œMost patients undergo invasive procedures for resection or biopsy of the affected organ to exclude other conditions. Unfortunately, most of those patients get dismissed by the clinicians, given the good news that their disease was not malignancy. Many of them have recurrence of the condition in other organs after a few months or years.â€
Rheumatologist Arezou Khosroshahi, MD
In the case report, a woman was admitted to Massachusetts General Hospital, because of shoulder and abdominal pain and an accumulation of fluid around her lungs. Surgeons removed a softball-sized mass from her right lung. The mass did not appear to be cancerous, but instead seemed to be the result of some kind of fibrous inflammation, and the patientÂ was treated with antibiotics. Read more
LabTV features hundreds of young researchers from universities and institutes around the United States, who tell the public about themselves and their research. The videos include childhood photos and explanations from the scientists about what they do and what motivates them.Â
The two Emory labs are: Malu Tansey’s lab in the Department of Physiology, which studies the intersection of neuroscience and immunology, focusing on neurodegenerative disease, and Mike Davis’ lab in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, which is developing regenerative approaches and technologies for heartÂ disease in adults and children. Read more
Note — this study looked at antibody responses to flu vaccines, but didn’t assess protection: whether study participants actually became sick with flu or not.
Our write-up is here.Â Immunity’s preview, from the Karolinska Institute’s Petter Brodin, is here,Â Cell Press’s press release is here.
ThreeÂ points we wanted to call attention to:
*Long-lasting antibodiesÂ AÂ surprising finding was how the “molecular signatures” that predict the strength of the immune response a few weeks after vaccination did not predict how long anti-flu antibodies stayed around.Â Instead, a separate set of signatures predicted the durability of antibody levels.
These distinct signaturesÂ may beÂ connected with how plasmaÂ cells, responsible for antibody production, need to findÂ homes in the bone marrow. That sounds like the process highlighted by Eun-Hyung Lee and colleagues in an Immunity paper published in July. In bone marrow samples from middle-aged volunteers, her team had found antibody-secreting cells that surviveÂ from childhood infections.
*Interfering (?) activation of NK cells/monocytes in elderlyÂ While the researchers found people older than 65 tended to have weaker antibody responses to vaccination, thereÂ wereÂ common elements of molecular signatures that predicted strong antibody responses in younger and older volunteers.Â However, elderly volunteers tended to have stronger signatures from immune cells that are not directly involved in producing antibodies (monocytes and â€˜natural killerâ€™ cells), both at baseline and after vaccination.
From the discussion: “This indicates a potential connection between the baseline state of the immune system in the elderly and reduced responsiveness to vaccination.” Additional comments on this from Shane Crotty in Brad Fikes’ article for the Union Tribune.
*The mountain of dataÂ from this and similar studies is available for use by other researchers on the web site ImmPort.
Graft-vs-host disease is a common and potentially deadly complication following bone marrow transplants, in which immune cells from the donated bone marrow attack the recipientâ€™s body.
Winship Cancer Instituteâ€™s Ned Waller and researchers from Childrenâ€™s Healthcare of Atlanta and Yerkes National Primate Research Center were part of a recent Science Translational Medicine paper that draws a bright red circle around aurora kinase A as a likely drug target in graft-vs-host disease.
Aurora kinases are enzymes that control mitosis, the process of cell division, and were first discovered in the 1990s in yeast, flies and frogs. Now drugs that inhibit aurora kinase A are in clinical trials for several types of cancer, and clinicans are planning to examine whether the same type of drugs could help with graft-vs-host disease.
Leslie Kean, a pediatric cancer specialist at Seattle Childrenâ€™s who was at Emory until 2013, is the senior author of the STM paper. Seattle Childrens’ press releaseÂ says that Kean wears a bracelet around her badge from a pediatric patient cured of leukemia one year ago, but who is still in the hospital due to complications from graft-vs-host. Read more
I was struck by one part of Mirko Paiardini’s paper that was published this week in Journal of Clinical Investigation. It describes aÂ treatment aimed at repairing immune function in SIV-infected monkeys, with an eye toward helping people with HIV one day.Â One of the goals of their IL-21 treatment is to restoreÂ intestinal Th17 cells, which are depleted by viral infection.Â In this context, IL-21’s effect is anti-inflammatory.
However, Th17 cells are also involved in autoimmune disease. A recent Cell Metabolism paper from endocrinologist Roberto Pacifici and colleagues examinesÂ Th17 cells, with the goal of treating bone loss coming from an overactive parathyroid. In that situation, too many Th17 cells are bad and they need to be beaten back. Fortunately, bothÂ an inexpensive blood pressure medication and a drugÂ under development for psoriasisÂ seem to do just that.