Stories about: immune tolerance

Link found between chronic inflammation, autoimmune disorders and “false alarms”

Viruses (pictured here) have a genetic signature that a receptor called MDA5 recognizes. But when MDA5 confuses the body's own genetic material with that of a virus, disease ensues.
Viruses have a genetic signature that a human receptor called MDA5 recognizes, causing the immune system to attack. But when MDA5 confuses the body’s own genetic material for that of a virus, disease ensues.

The human body’s innate immune system employs a variety of “sensors” for identifying foreign invaders such as viruses. One such viral sensor is a receptor called MDA5, found in every cell of the body.

Inside each cell, MDA5 constantly scans genetic material, checking if it’s native to the body or not. As soon as MDA5 identifies the genetic signature of a viral invader, it trips a system-wide alarm, triggering a cascade of immune activity to neutralize the threat.

But if a genetic mutation to MDA5 causes it to confuse some of the body’s own genetic material for being foreign, “false alarms” can lead to unchecked inflammation and disease. Scientists from Boston Children’s Hospital have discovered a new link between MDA5’s ability to discriminate between “self” and “non-self” genetic material — called RNA duplexes — and a spectrum of autoimmune disorders.

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Transfusing engineered red blood cells to protect against autoimmune disease

Red blood cells, pictured here, could be engineered to protect against autoimmune disease
Transfusions of engineered red blood cells could help prevent and/or treat autoimmune disease.

Autoimmune disease is usually treated using general immunosuppressants. But this non-targeted therapy leaves the body more susceptible to infection and other life-threatening diseases.

Now, scientists at Boston Children’s Hospital, the Massachusetts Institute of Technology (MIT) and the Whitehead Institute for Biomedical Research think they may have found a targeted way to protect the body from autoimmune disease. Their approach, published in Proceedings of the National Academy of Sciences, uses transfusions of engineered red blood cells to re-train the immune system. Early experiments in mice have already shown that the approach can prevent — and even reverse — clinical signs of two autoimmune diseases: a multiple-sclerosis (MS)-like condition and Type 1 diabetes.

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Food allergies: Turning tolerance back on

Mast cell food allergy
Mast cells don’t simply cause acute allergic reactions. They also turn off immune tolerance. But that could change. (Bruce Blaus/Wikimedia Commons)

Hans Oettgen, MD, PhD, is Associate Chief of the Division of Allergy and Immunology at Boston Children’s Hospital.  He leads a research group investigating mechanisms of allergic diseases.

Not long ago I received a wonderful email from “Sam,” an 18-year-old young man with peanut allergy. He was participating in a clinical trial of oral immunotherapy (OIT) being carried out by colleagues here at Boston Children’s Hospital.

In OIT, patients receive initially minute doses of the food to which they are allergic. Then, over many weeks, they ingest increasing amounts, under close medical monitoring at the hospital.

OIT’s goal is to get patients to tolerate previously allergenic foods by inducing their bodies to produce Treg cells, or regulatory T cells. These are the master controllers of our immune responses, and their actions include suppressing allergic responses to foods. Food ingestion, as in OIT, will eventually induce food-specific Treg cells, but it can be a long and cumbersome process. For Sam, ingesting escalating doses of peanuts proved difficult: His email described frequent reactions ranging from stomachaches and itchiness to difficulty breathing.

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Giving the immune system a new start, to prevent transplant rejection

Leveling the immune system might let the body rebuild one that’s tolerant of a transplanted kidney. (Photo: Tom Ulrich)

As the science of transplantation has gotten better, the patients whose lives are saved by other people’s organs are living longer and longer. But they’re paying a price—a lifetime of immunosuppressive drugs.  William Harmon, chief of Nephrology at Children’s Hospital Boston, is trying to change that.

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