Quinn Eastman

2B4: potential immune target for sepsis survival

Emory immunologists have identified a potential target for treatments aimed at reducing mortality in sepsis, an often deadly reaction to infection.

2B4 is an inhibitory molecule found on immune cells. You may have heard of PD1, which cancer immunotherapy drugs block in order to re-energize the immune system. 2B4 appears to be similar; it appears on exhausted T cells after chronic viral infection, and its absence can contribute to autoimmunity.

In their new paper in Journal of Immunology, Mandy Ford, Craig Coopersmith and colleagues show that 2B4 levels are increased on certain types of T cells (CD4+ memory cells) in human sepsis patients and in a mouse model of sepsis called CLP (cecal ligation + puncture). Genetically knocking out 2B4 or blocking it with an antibody both reduce mortality in the CLP model. The effect of the knockout is striking: 82 percent survival vs 13 percent for controls.

How does it work? When fighting sepsis, 2B4 knockout animals don’t have reduced bacterial levels, but they do seem to have CD4+ T cels that survive better. CD4+ T cells, especially memory cells, get killed in large numbers during sepsis, and this is thought to contribute to mortality. Read more

Posted on by Quinn Eastman in Immunology Leave a comment

EHR data superior for studying sepsis

Are there more cases of a given disease because something is causing more, or because doctors have become more aware of that disease? A recent paper in JAMA tackles this question for sepsis, the often deadly response to infection that is the most expensive condition treated in US hospitals.

Researchers from several academic medical centers, including Emory, teamed up to analyze sepsis cases using two methods. The first is based on the ICD (International Classification of Diseases) codes recorded for the patient’s stay in the hospital, which the authors refer to as “claims-based.” The second mines electronic medical record (EHR) data, monitoring the procedures and tests physicians used when treating a patient. The first approach is easier, but might be affected by changing diagnosis and coding practices, while the second is not possible at every hospital.

“This project was undertaken by several large, high quality institutions that have the ability to well characterize their sepsis patients and connect their EHR data,” says Greg Martin, MD, who is a co-author of the JAMA paper along with David Murphy, MD, PhD. The lead author, Chanu Rhee, MD, MPH, is from Brigham and Women’s Hospital, and the entire project was part of a Prevention Epicenter program sponsored by the Centers for Disease Control and Prevention.  Read more

Posted on by Quinn Eastman in Immunology Leave a comment

New pediatric digestive/liver disease gene identified by international team

In a study published this month in Hepatology, a multinational team of researchers describes a newly identified cause of congenital diarrhea and liver disease in children.

The rare disorder is characterized by significant diarrhea beginning soon after birth, low serum levels of fat-soluble vitamins and evidence of liver disease. Despite continued symptoms, with medical support, the children grow and develop normally, at least to the age of 12.

From left to right: Mutaz Sultan, Orly Elpeleg and Paul Dawson, representing three collaborating institutions.

Researchers from Emory University School of Medicine and Children’s Healthcare of Atlanta, working with colleagues from Makassed Hospital, Al-Quds University and Hadassah Medical Center, Hebrew University of Jerusalem studied a family with two children from the Palestinian territories who suffer from the disorder.

The team found that both children had inherited a mutation in a gene responsible for the transport of bile acids, which facilitate the digestion and absorption of dietary fats and fat-soluble vitamins. Although mutations had been identified in other genes important for the recycling of bile acids, this is the first report in humans of disease-associated defects in this gene, called Organic Solute Transporter-beta (SLC51B).

Almost 20 years ago, pediatric GI & hepatology researcher Paul Dawson, PhD, and colleagues identified mutations in another bile acid transporter gene (ASBT; SLC10A2) that caused congenital bile acid diarrhea.

“Even at that time, we knew that there were patients with similar symptoms that did not carry mutations in ASBT. But the genetic cause remained a mystery.” Dawson says. “What’s distinctive about this report is that these patients also have features of liver disease, which was not observed in previously described congenital bile acid diarrhea patients.” Read more

Posted on by Quinn Eastman in Uncategorized Leave a comment

Tug of war between Parkinson’s protein and growth factors

Alpha-synuclein, a sticky and sometimes toxic protein involved in Parkinson’s disease (PD), blocks signals from an important brain growth factor, researchers have discovered.

The results were published this week in PNAS.

The finding adds to evidence that alpha-synuclein is a pivot for damage to brain cells in PD, and helps to explain why brain cells that produce the neurotransmitter dopamine are more vulnerable to degeneration.

Alpha-synuclein is a major component of Lewy bodies, the protein clumps that are a pathological sign of PD. Also, duplications of or mutations in the gene encoding alpha-synuclein drive some rare familial cases.

In the current paper, researchers led by Keqiang Ye, PhD demonstrated that alpha-synuclein binds and interferes with TrkB, the receptor for BDNF (brain derived neurotrophic factor). BDNF promotes brain cells’ survival and was known to be deficient in Parkinson’s patients. When applied to neurons, BDNF in turn sends alpha-synuclein away from TrkB.  [Ye’s team has extensively studied the pharmacology of 7,8-dihydroxyflavone, a TrkB agonist.]

A “tug of war” situation thus exists between alpha-synuclein and BDNF, struggling for dominance over TrkB. In cultured neurons and in mice, alpha-synuclein inhibits BDNF’s ability to protect brain cells from neurotoxins that mimic PD-related damage, Ye’s team found. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

From stinging to soothing: fire ant venom may lead to skin treatments

Compounds derived from fire ant venom can reduce skin thickening and inflammation in a mouse model of psoriasis, Emory and Case Western scientists have shown.

The results were published on Sept. 11 in Scientific Reports.

Update: When this paper was published, Lab Land received an email providing anecdotal support for effectiveness in humans. “I have suffered with psoriasis all my life and in 2015, I went on an expedition to Central America. I got eaten alive by fire ants, as they managed to get into my socks. My psoriasis however got better for a time, and as somebody who has directly experienced fire ant venom, I strongly believe that there is a correlation between it and psoriasis.”

The findings could lead to new treatments for psoriasis, a common autoimmune skin disease. Topical steroids are now most frequently used for mild to moderate psoriasis, but they have side effects such as skin thinning and easy bruising.

Solenopsins are the main toxic components of fire ant venom. They chemically resemble ceramides, which are lipid-like molecules essential for maintaining for the barrier function of the skin. Ceramides can be found in many skin care products.

Ceramides can act as a double-edged sword, says lead author Jack Arbiser, MD, PhD, professor of dermatology at Emory University School of Medicine. Under certain conditions they can be converted by cells into S1P (sphingosine-1-phosphate), an inflammatory molecule.

Arbiser and his colleagues devised two solenopsin analogs that look like ceramides, but can’t be degraded into S1P. They then tested them in a mouse model of psoriasis, applying the compounds in a one percent skin cream for 28 days. Read more

Posted on by Quinn Eastman in Immunology Leave a comment

Troublemaker cells predict immune rejection after kidney transplant

Emory scientists have identified troublemaker cells—present in some patients before kidney transplantation—that are linked to immune rejection after transplant. Their results could guide transplant specialists in the future by helping to determine which drug regimens would be best for different groups of patients. Eventually, the findings could lead to new treatments that improve short- and long-term outcomes.

Transplant patients used to have no choice but to take non-specific drugs to prevent immune rejection of their new kidneys. While these drugs, called calcineurin inhibitors, are effective at preventing early rejection, they lack specificity for the immune system and ironically can damage the very kidneys they are intended to protect. In addition, their side effects lead to higher rates of high blood pressure, diabetes, and cardiovascular disease, ultimately shortening the life of the transplant recipient. This changed with the advent of costimulation blockers, which avoid these harmful side effects. Emory transplant surgeons Chris Larsen and Tom Pearson, together with Bristol-Myers Squibb, helped develop one of these new drugs called belatacept, which blocks signals through the costimulatory receptor CD28.

In a long-term clinical study of belatacept, kidney transplant patients tended to live longer with better transplant function when taking belatacept compared with calcineurin inhibitors. Despite these desirable outcomes, acute rejection rates were higher in patients treated with belatacept.

Andrew Adams, an Emory transplant surgeon who focuses on costimulation blockade research, notes: “While the acute rejection seen with belatacept is treatable with stronger immunosuppression, there may be long-term effects that linger and impair late outcomes.”

Most transplant centers have not yet adopted this new therapy as their standard of care because of the higher rejection rate as well as other logistical concerns, thus limiting patients’ access to potential health benefits afforded with belatacept treatment.

Adams and colleague Mandy Ford have identified certain types of memory T cells, which typically provide long-lasting immunity to infection, as potential mischief-makers in the setting of organ transplants treated with belatacept. Evidence is accumulating that the presence of certain memory T cells can predict the likelihood of “belatacept-resistant” rejection. Two recent papers in American Journal of Transplantation by Ford and Adams support this idea. Read more

Posted on by Quinn Eastman in Immunology Leave a comment

Imaging sleep drunkenness: #IHAW2017

At some point, everyone has experienced a temporary groggy feeling after waking up called sleep inertia. Scientists know a lot about sleep inertia already, including how it impairs cognitive and motor abilities, and how it varies with the time of day and type of sleep that precedes it. They even have pictures of how the brain wakes up piece by piece.

People with idiopathic hypersomnia or IH display something that seems stronger, termed “sleep drunkenness,” which can last for hours. Czech neurologist Bedrich Roth, the first to identify IH as something separate from other sleep disorders, proposed sleep drunkenness as IH’s defining characteristic.

Note: Emory readers may recall the young Atlanta lawyer treated for IH by David Rye, Kathy Parker and colleagues several years ago. Our post today is part of IH Awareness Week® 2017.

Sleep drunkenness is what makes IH distinctive in comparison to narcolepsy, especially narcolepsy with cataplexy, whose sufferers tend to fall asleep quickly. Those with full body cataplexy can collapse on the floor in response to emotions such as surprise or amusement. In contrast, people with IH tend not to doze off so suddenly, but they do identify with the statement “Waking up is the hardest thing I do all day.”

At Emory, neurologist Lynn Marie Trotti and colleagues are in the middle of a brain imaging study looking at sleep drunkenness.

“We want to find out if sleep drunkenness in IH is the same as what happens to healthy people with sleep inertia and is more pronounced, or whether it’s something different,” Trotti says. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

Enhancing the brain’s clean up crews

Enhancing the brain’s own clean-up crews could be a strategy for handling the toxic proteins driving several neurodegenerative diseases, new research suggests.

Astrocytes, an abundant supportive cell type in the brain, are better than neurons at disposing of mutant huntingtin, the toxic protein that drives Huntington’s disease pathology, Xiao-Jiang Li and colleagues report in this week’s PNAS.

One reason why astrocytes are better at toxic protein defense than neurons is: they have less of an inhibitory protein called HspBP1. The scientists show that using CRISPR/Cas9 to “knock down” HspBP1 can help neurons get rid of mutant huntingtin and reduce early pathological signs.

Read more

Posted on by Quinn Eastman in Neuro Leave a comment

Cancer drug discovery: targeting DNA repair

Standard anticancer treatments, such as chemotherapy, target rapidly dividing cells by damaging their DNA. A newer strategy is to undercut cancer cells’ ability to repair DNA damage.

Radiation oncologist David Yu, MD, PhD

Winship Cancer Institute investigators led by David Yu, MD, PhD have identified a distinct function in DNA double strand break repair for an enzyme called SAMHD1. Depleting or inhibiting SAMHD1 could augment anticancer treatments that induce DNA double-strand breaks, such as ionizing radiation or PARP inhibitor drugs, they suggest. Ionizing radiation is a mainstay of cancer treatment and PARP inhibitors are being developed for several cancer types.

The findings were published this week in Cell Reports (open access).

SAMHD1 was known for its ability to chop up the building blocks of DNA, and had come to the attention of virologists because it limits the ability of retroviruses such as HIV to infect some cell types. The first author of the paper, postdoc Waaqo Daddacha, PhD, previously studied SAMHD1 with virologist Baek Kim, PhD, professor of pediatrics.

Cancer researchers had already sought to harness a retroviral protein called Vpx, which viruses evolved to disable SAMHD1. Acute myeloid leukemia cells use SAMHD1 to get rid of the drug cytarabine, so Vpx can sensitize AML to that drug. The Cell Reports paper shows that virus-like particles carrying Vpx could be deployed against other types of cancer, in combination with agents that induce DNA double-strand breaks. Read more

Posted on by Quinn Eastman in Cancer Leave a comment

Update on SIV remission studies

Tab Ansari’s research at Emory/Yerkes on how an antibody treatment can push monkeys infected with SIV into remission was published in Science last year. At that time, Ansari told Lab Land about follow-up experiments to probe which immune cells are needed for this effect, which surprised many HIV/AIDS experts.

Ansari’s partner on the project, NIAID director Anthony Fauci, described the follow-up work in July at the International AIDS Society Conference in Paris. We thank Treatment Action Group’s Richard Jefferys for taking notes and posting a summary:

The approach that the researchers took was to deplete different types of immune cells in the animals controlling SIV viral load, then assess whether this led to an increase in viral replication. The experiments compared:

*Antibodies to the CD8 receptor alpha chain, which deplete CD8 T cells, natural killer T cells (NKTs) and natural killer (NK) cells

*Antibodies to the CD8 receptor beta chain, which deplete CD8 T cells

*Antibodies to CD20, which deplete B cells

According to Fauci’s slides, which are available online, there was a transient rebound in viral load with the CD8 alpha antibody and to a small degree with the CD8 beta. This suggests NKTs and NK cells are making a contribution to the observed control of SIV replication, but a role for CD8 T cells cannot be ruled out.

For comparison, a study from Guido Silvestri and colleagues at Yerkes published in 2016 found that treating SIV-infected monkeys with anti-CD8 antibodies, without stopping antiretroviral drugs, resulted in a rebound in virus levels. [They used ultrasensitive assays to detect the rebound.] However, the Yerkes team only used antibodies to the CD8 receptor alpha chain.

Read more

Posted on by Quinn Eastman in Immunology Leave a comment
1 2 3 4 5 6 7 8 9 10 ... 51 52   Next »