Warren symposium follows legacy of geneticist giant

If we want to understand how the brain creates memories, and how genetic disorders distort the brain’s machinery, then the fragile X gene is an ideal place to start. That’s why the Stephen T. Warren Memorial Symposium, taking place November 28-29 at Emory, will be a significant event for those interested in neuroscience and genetics. Stephen T. Warren, 1953-2021 Warren, the founding chair of Emory’s Department of Human Genetics, led an international team that discovered Read more

Mutations in V-ATPase proton pump implicated in epilepsy syndrome

Why and how disrupting V-ATPase function leads to epilepsy, researchers are just starting to figure Read more

Tracing the start of COVID-19 in GA

At a time when COVID-19 appears to be receding in much of Georgia, it’s worth revisiting the start of the pandemic in early 2020. Emory virologist Anne Piantadosi and colleagues have a paper in Viral Evolution on the earliest SARS-CoV-2 genetic sequences detected in Georgia. Analyzing relationships between those virus sequences and samples from other states and countries can give us an idea about where the first COVID-19 infections in Georgia came from. We can draw Read more

rituximab

Leaving out sugar makes a better antibody drug

There’s a bit of sugar attached to your billion-dollar biotech product. Omitting the sugar (fucose) can help the product work better, Emory immunologists think.

Fucosylation is the red triangle on this diagram of the carbohydrate modifications of antibodies. Adapted from KTC Shade + RM Anthony, Antibodies (2013) and used through Creative Commons license.

Many drugs now used to treat cancer and autoimmune diseases are antibodies, originally derived from the immune system. A classic example of a “therapeutic antibody” is rituximab, a treatment for B cell malignancies that was FDA-approved in 1997. It has been responsible for billions of dollars in revenue for its maker, pharmaceutical giant Roche.

Researchers at Emory Vaccine Center previously observed that in a mouse model of chronic viral infection, a traffic jam inside the body limits how effective therapeutic antibodies can be. One of the ways these antibodies work is to grab onto malignant or inflammatory cells. One end of the antibody is supposed to bind the target cell, while another is a flag for other cells to eliminate the target cell. During a chronic viral infection, a mouse’s immune system is producing its own antibodies against the virus, which form complexes with viral proteins. These immune complexes prevented the injected antibodies from depleting their target cells.

In a recent Science Immunology paper, postdoc Andreas Wieland, Vaccine Center director Rafi Ahmed and colleagues showed that antibodies that lack fucosylation have an enhanced ability to get rid of their intended targets. Fucosylation is a type of sugar modification of the antibody. (It is the red triangle in the diagram, provided by Wieland.) When it is not present, then the “flag for removal” region of the antibody can interact more avidly with the Fc gamma receptor on immune cells. Thus, the introduced antibodies can compete more effectively with the antibodies being produced by the body already.

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Posted on by Quinn Eastman in Immunology 1 Comment

Immune ‘traffic jam’ from viral infection

Several drugs now used to treat cancer and autoimmune diseases are actually repurposed tools derived from the immune system. One of the ways these “therapeutic antibodies” work is to grab onto malignant or inflammatory cells and escort them to their doom.

Emory researchers have found that in a mouse model of chronic viral infection, a kind of traffic pileup inside the body limits how effective therapeutic antibodies can be.

The results, published this week in Immunity, have implications for biotechnology researchers who continue to refine antibodies for therapeutic purposes, as well as bolster our understanding of how chronic viral infections impair the immune system.

Researchers led by Rafi Ahmed, PhD, director of the Emory Vaccine Center, were studying mice infected by LCMV (lymphocytic choriomeningitis virus). They injected several antibodies with the goal of removing various types of immune cells from the mice.  One end of the antibody molecule is supposed to bind the target cell, while another acts as a flag for other cells to get rid of the target cell.

However, during a chronic LCMV infection, the mouse’s immune system is producing its own antibodies against the virus, which form complexes with viral proteins. These immune complexes prevented the injected antibodies from having the effect the scientists wanted, which was to deplete their target cells.

Excessive amounts of immune complexes appear to be “clogging” the Fc gamma receptors that immune cells would use to grab the antibodies bound to the target cell, says postdoctoral fellow Andreas Wieland, PhD, first author of the Immunity paper. That these immune complexes form was not news; but how much they interfere with other antibodies was, Wieland says. Fc gamma receptors were already known to be important for antibodies to be effective against influenza and HIV. Read more

Posted on by Quinn Eastman in Immunology Leave a comment