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.
The first week of a baby’s life is a time of rapid biological change. The newborn must adapt to living outside the womb, suddenly exposed to new bacteria and viruses. Yet scientists know surprisingly little about these early changes.
Reporting in today’s Nature Communications, an international research team provides the most detailed accounting to date of the molecular changes that occur during a newborn’s first seven days. The team pioneered a technique to extract volumes of data from a tiny amount of newborn blood — including what genes are turned on, what proteins the body is making and what metabolites are changing.
Second in a two-part series on transplant tolerance. (See part one.)
Our immune system has two major kinds of T cells. T helper cells, also known as effector T cells, tend to rev up our immune responses, while T regulatory cells tend to suppress or downregulate them. Last week we reported that bolstering populations of T regulatory cells might help people tolerate organ transplants better. A new study turned its focus to T helper cells, and found that an imbalance of these cells causes an exaggerated immune response that may also contribute to transplant rejection.
The study also showed, in mice and in human cells in a dish, that the immune imbalance can be potentially reversed pharmacologically. Findings were published yesterday in the Journal of Clinical Investigation. …
First in a two-part series on transplant tolerance. Read part two.
Although organ transplant recipients take drugs to suppress the inflammatory immune response, almost all eventually lose their transplant. A new approach, perhaps added to standard immunosuppressant treatment, could greatly enhance people’s long-term transplant tolerance, report researchers at Boston Children’s Hospital.
The approach, which has only been tested in mice as of yet, works by maintaining a population of T cells that naturally temper immune responses. It does so by turning on a gene called DEPTOR, which itself acts as a genetic regulator. In a study published July 3 in the American Journal of Transplantation, boosting DEPTOR in T cells enabled heart transplants to survive in mice much longer than usual. …
Research tells us that the “good” bacteria that inhabit our intestines help to regulate our metabolism. A new study in fruit flies shows one of the ways in which these commensal microbes keep us metabolically fit.
The findings, published today in Cell Metabolism, suggest that innate immune pathways, our first line of defense against bacterial infection, have a side job that’s equally important.
The intestine’s digestive cells use an innate immune pathway to respond to harmful bacteria by producing antimicrobial peptides. But other intestinal cells, enteroendocrine cells, use the same pathway, known as IMD, to respond to “good” bacteria — by fine-tuning body metabolism to diet and intestinal conditions.
“What’s most interesting to me is that some innate immune pathways aren’t just for innate immunity,” says Paula Watnick, MD, PhD, of the Division of Infectious Diseases at Boston Children’s Hospital. “Innate immune pathways are also listening to the ‘good’ bacteria – and responding metabolically.” …
Antibiotic resistance is a growing threat in bacterial pneumonia. While treatments that stimulate the immune system can help the body fight the invaders, these treatments can also cause inflammation that damages and weakens lung tissue.
Increasing evidence supports the idea that the bacteria living in our intestines early in life help shape our immune systems. Factors like cesarean birth, early antibiotics, having pets, number of siblings and formula feeding (rather than breastfeeding) may affect our microbial makeup, or microbiota, and may also affect our likelihood of developing allergies.
Could giving an allergic person the microbiota of a non-allergic person prevent allergic reactions? In a new clinical trial, a team led by Rima Rachid, MD, of Boston Children’s Division of Allergy and Immunology, is testing this idea in adults with severe peanut allergies. The microbiota will be delivered through fecal transplants — in the form of frozen, encapsulated poop pills. …
The basic biological mechanisms that underpin autoimmune disorders are finally coming to light. Researchers in Boston’s Longwood medical area — a neighborhood where the streets are flanked by hospitals, research institutions and academic centers — are setting the stage for a new wave of future therapies that can prevent, reduce or even reverse symptoms of disease.
Inside the lab of Michael Carroll, PhD, scientists are working to understand how and why immune cells start to attack the body’s own tissues; it turns out the immune system’s B cells compete with each other in true Darwinian fashion. On the way to this discovery, the lab has flushed out new potential drug targets that could ease autoimmune symptoms — or stop them entirely — by “resetting” the body’s tolerance to itself.
The implications for a link between inflammation and synapse loss go beyond lupus because inflammation underpins so many diseases and conditions, ranging from Alzheimer’s to viral infection and even to to chronic stress. In which case, are we all losing synapses to some varying degree? Carroll plans to find out.
“We’ve found that chronic inflammation and autoinflammatory disorders can originate from genetic mutations to MDA5 that cause it to misrecognize ‘self’ as ‘non-self,’ essentially launching the immune system into self-attack mode,” said Hur. …
Eczema affects about 17 percent of children in developed countries. Often, it’s a gateway to food allergy and asthma, initiating an “atopic march” toward broader allergic sensitization. There are treatments – steroid creams and a recently approved biologic – but they are expensive or have side effects. A new study in Science Immunology suggests a different approach to eczema, one that stimulates a natural brake on the allergic attack.
The skin inflammation of eczema is known to be driven by “type 2” immune responses. These are led by activated T helper 2 (TH2) cells and type 2 innate lymphoid cells (ILC2s), together known as effector cells. Another group of T cells, known as regulatory T cells or Tregs, are known to temper type 2 responses, thereby suppressing the allergic response.
Yet, if you examine an eczema lesion, the numbers of Tregs are unchanged. Interestingly, Tregs comprise only about 5 percent of the body’s T cells, but up to 50 percent of T cells in the skin. …
The hepatitis B vaccine is one of only three vaccines that are routinely given to newborns in the first days of life. But the current hepatitis B vaccine has limitations: multiple “booster” doses are needed, and it can’t be given to premature babies weighing less than 2 kg.
Annette Scheid, MD, a neonatologist at Brigham and Women’s Hospital, is interested in leveraging infant immune differences to create a better hepatitis B vaccine for newborns. “The reality is that we have to vaccinate several times,” she says. “But we all dream of a vaccine that you give only once.” …