The human immune system includes about a dozen major cell
types with specialized roles in the body’s defenses. They serve as sentries,
identify threats, mobilize troops, capture and transport invaders, interrogate
and kill those deemed dangerous and clear the battlefield of casualties. This intricate
command-and-control system is what enables us to fend off most of the dangerous
bacteria and viruses that come our way.
But in patients who suffer from inflammatory bowel disease (IBD), the immune system itself becomes the enemy. Even when the body faces no threat, immune cells called “helper T cells” take up arms, resulting in a kind of perpetual warfare that — far from being helpful — causes collateral damage to the gut.
“The system goes into overdrive,” says Yu Hui Kang, an
immunology graduate student at Harvard Medical School and a researcher at
Boston Children’s Hospital.
“These cells have gone too far, and they can’t stop.”
Now Kang and colleagues in the lab of Scott Snapper, MD, PhD, director of Boston Children’s Inflammatory Bowel Disease Center, may have found a way to turn the tables on the immune system by recruiting its own “natural killer” cells to wipe out the harmful T cells. Though clinical applications are years away, the work suggests new avenues for developing treatments for the debilitating disease.
Boston Children’s Hospital has embarked on a strategic initiative to accelerate and expand its research genomics gateway, with plans to sequence the DNA of 3,000 patients with epilepsy or inflammatory bowel disease and their family members. Patients will have access to enroll in this pilot study if their condition is of likely genetic origin but lack a diagnosis after initial clinical genetic testing.
Sequencing will cover the entire exome, containing all of a person’s protein-coding genes. The Epilepsy and IBD were chosen for the pilot because Ann Poduri, MD, MPH and Scott Snapper, MD, PhD, have already made huge inroads into the genetics of these respective disorders. Both have built large, well characterized patient databases for research purposes, have disease-specific genetic expertise and have begun using their findings to inform their patients’ care. …
Inflammatory bowel disease (IBD) is miserable for anyone, but when it strikes a child under age 5, it’s much more severe, usually causing bloody diarrhea, wrenching abdominal pain and stunted growth. Early-onset IBD is rare, but on the rise: For reasons unknown, its incidence is increasing by about 5 percent per year in some parts of the world.
A recently identified form of early-onset IBD shows up within months of birth, causing severe inflammation in the large intestine and abscesses around the anus. Recently linked to genetic mutations in the cellular receptor for a signaling protein, interleukin-10 (IL-10), it can also lead to lymphoma later in life.
As with all early-onset IBD, IL-10-receptor deficiency has no good treatment. A bone marrow transplant is actually curative, but carries many risks, especially in infants.
“We’ve been trying to understand why IBD in these children is so severe and presents so early,” says Dror Shouval, MD, a pediatric gastroenterologist at Boston Children’s Hospital and a fellow in the lab of Scott Snapper, MD, PhD. The beginnings of such an understanding—detailed recently in the journal Immunity—could lead to a new treatment approach for this and perhaps other kinds of early-onset IBD. …