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Covid’s gift: A window into the human immune response as it was happening

March 28, 2024
Reporter, Morning Rounds Writer
Good morning. Immunology takes center stage today, with Helen Branswell's illuminating look back at the unprecedented chance Covid-19 gave science to understand the human immune system. Then Megan Molteni explains how scientists revved up immune systems in old mice. Isabella Cueto tells us about clues to multiple sclerosis and Theresa Gaffney brings us a study connecting the microbiome to kidney autoimmune disease. But wait — we have decaf coffee and food as medicine on the menu, too.

infectious disease

Covid's gift: A window into the human immune response — in real timeCovidResearch_Illustration_MollyFerguson_021924

Molly Ferguson for STAT

Immunologists would never deny Covid-19's worldwide devastation, but if you look through their eyes back to 2020, when the disease still had no name but was spreading across the world, you'll see a silver lining. For a window of time that has now closed, they could watch what happened when 8 billion people were exposed to a novel coronavirus. They had a front-row seat to witness how we developed  immunity to the virus — and its variants — at a cellular level.

Pandemics have emerged before, but this time scientists had the tools to study how the immune system awakens to a new threat and develops defenses against it. "You see textbook immunology happening in real time," said Marc Veldhoen, a professor of immunology at the University of Lisbon. "You couldn't have designed a better experiment," said Stephen Deeks, an HIV researcher at the University of California, San Francisco. STAT's Helen Branswell tells us what they did with this opportunity — and what they learned.


in the lab

Scientists rejuvenate immune systems in old mice

The "twilight of immunity" has a much more poetic flavor than almost any other phrase describing our bodies' deterioration with age. STAT's Megan Motleni calls this to mind in today's story about research seeking to explain how our aging immune systems leave us more vulnerable to infection. Reporting in Nature yesterday on their experiments in mice, scientists traced waning immune strength to the bone marrow where blood and immune cells originate from hematopoietic stem cells. The balance of immune memory cells, blood cells, and front-line defenders shifts over time depending on what kind of cells are produced, with an impact on how well they work against invaders.

When the scientists restored a youthful balance of these cells with injections of antibodies, they were able to rejuvenate the immune systems of older mice — allowing them to better fend off viral attacks. Megan has more on whether and how this might hold up in humans, plus the rich history behind the work.


health

Could the FDA ban decaf?

If consumer health advocates get their way, the FDA will ban a key chemical used to decaffeinate coffee beans that is almost but not entirely removed during the process. Methylene chloride, a since-banned paint stripper, is used by major coffee U.S. companies including Starbucks, Dunkin Donuts, and Folgers. In its petition the Environmental Defense Fund says a 66-year-old federal law requires the agency to ban the additive because it has been proven to cause cancer in rodents. The FDA estimated in 1985 that the risk of cancer for decaf drinkers was one in a million.

"There's more methylene chloride in the water that you brew your decaf with than came with the decaf roasted beans," said James Coughlin, a food toxicology consultant to the coffee industry. "It's not as if there's no good substitute," said Maria Doa, of the Environmental Defense Fund. STAT's Nicholas Florko has the details and the history.



closer look

If food is medicine, what does that mean? Coalition sets standards to define itDiane_CommunityServings03

Alissa Ambrose / STAT

Food as medicine makes intuitive sense. Eating better can help treat certain medical conditions, including HIV and heart failure. The trick is how to define what constitutes a medically tailored meal. To fill that gap, the Food is Medicine Coalition, a group of community-based nonprofit food providers, released its accreditation standard yesterday, sharing it first with STAT's Nicholas Florko. Some requirements:

  • Organizations must have one accredited full-time dietitian on staff for every 1,000 clients they serve. 
  • No foods with artificial sweeteners, preservatives, or anything "ultra-processed." 
  • Foods must be cooked in a way that "preserves the nutrient value of the food," such as "baking, braising, and sautéing rather than frying."

The new standards were crafted to head off dilution of its goal — by commercial meal providers, among others —  to become as much a part of health care as drugs and medical devices. Nick has more, including some pushback.


chronic disease

Study discerns different MS subtypes

As chronic conditions go, multiple sclerosis is a difficult one to live with and to treat. Thought to be more common in women, it causes vision problems, fatigue, and weakness or spasms in the arms and legs, among many other symptoms. But the neurological condition doesn't always look the same. That spurred a team of scientists across Germany to look for clues in its earliest stages.  

A new study published yesterday in Science Translational Medicine sheds light on three specific subgroups of the disease they found in 500 patients, corresponding with differences in immunological activation early in their disease and sustained over the study's four years. This could suggest the disease arises through multiple immune system pathways, the researchers say. And because the groups responded differently to treatments over time, that might help inform their care and future drug development. STAT's Isabella Cueto has more


microbiome

Gut bacteria may play a role in a kidney disease

We're accustomed to the idea that a whole universe of microbes lives within us. But what are they doing? A new study implicates certain bacteria in the development of an autoimmune disease in the kidney. Writing in Science Translational Medicine, the researchers describe how these bacteria change antibodies inside us so much that the immune system thinks they are enemies. Then friendly fire leads to IgA nephropathy, an autoimmune disease of the kidneys, they conclude. 

The rare disease causes inflammation, blood in the urine, and potential kidney failure. The new research traces the bacterially modified antibody from the gut to the intestines, the bloodstream, and then the kidney. "We need to stop thinking about this passive, indirect effect of the microbiota on human disease and autoimmunity," study author James Gleeson said. "And more start looking for the direct ways that bacteria could be modifying molecules in the human body." STAT's Theresa Gaffney has more.


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