Immune system

Immune cells play surprising role in steady heartbeat

macrophages and heart cells
IT’S ELECTRIFYING Macrophages (green) “plug in” to heart cells (light purple and pink), providing an electrical boost that helps the heart cells contract and pump blood, a study in mice finds.

Immune system cells may help your heart keep the beat. These cells, called macrophages, usually protect the body from invading pathogens. But a new study published April 20 in Cell shows that in mice, the immune cells help electricity flow between muscle cells to keep the organ pumping.

Macrophages squeeze in between heart muscle cells, called cardiomyocytes. These muscle cells rhythmically contract in response to electrical signals, pumping blood through the heart. By “plugging in” to the cardiomyocytes, macrophages help the heart cells receive the signals and stay on beat.

Researchers have known for a couple of years that macrophages live in healthy heart tissue. But their specific functions “were still very much a mystery,” says Edward Thorp, an immunologist at Northwestern University’s Feinberg School of Medicine in Chicago. He calls the study’s conclusion that macrophages electrically couple with cardiomyocytes “paradigm shifting.” It highlights “the functional diversity and physiologic importance of macrophages, beyond their role in host defense,” Thorp says.

Matthias Nahrendorf, a cell biologist at Harvard Medical School, stumbled onto this electrifying find by accident.

Curious about how macrophages impact the heart, he tried to perform a cardiac MRI on a mouse genetically engineered to not have the immune cells. But the rodent’s heartbeat was too slow and irregular to…

Furry Friends Could Help Prevent Allergies and Obesity in Babies

Two of life’s great joys—dogs and babies—might be even better together. A study published in the journal Microbiome found higher levels of allergy-preventing bacteria in babies who lived with furry pets like dogs and cats.

The relationship between our environments, immune systems, and gut microbes is a tangled one. Studies have found that “dirty behaviors” like thumb-sucking and nail-biting might actually help protect kids against autoimmune conditions, as can living on a farm. So it’s not too much of a stretch to think that our four-legged companions might have a similarly beneficial effect.

To explore the idea further, researchers at the University of Alberta pulled data from the Canadian Healthy Infant Longitudinal Development (CHILD) study, which followed the lives…

Common virus may be celiac disease culprit

reovirus
A VIRAL TRIGGER A reovirus (illustrated here) may jump-start celiac disease by turning the immune system against gluten, a new study in mice suggests.

A common and usually harmless virus may trigger celiac disease. Infection with the suspected culprit, a reovirus, could cause the immune system to react to gluten as if it was a dangerous pathogen instead of a harmless food protein, an international team of researchers reports April 7 in Science.

In a study in mice, the researchers found that the reovirus, T1L, tricks the immune system into mounting an attack against innocent food molecules. The virus first blocks the immune system’s regulatory response that usually gives non-native substances, like food proteins, the OK, Terence Dermody, a virologist at the University of Pittsburgh, and colleagues found. Then the virus prompts a harmful inflammatory response.

“Viruses have been suspected as potential triggers of autoimmune or food allergy–related diseases for decades,” says Herbert Virgin, a viral immunologist at Washington University School of Medicine in St. Louis. This study provides new data on how a viral infection can change the immune system’s response to food, says Virgin, who wasn’t involved in the study.

Reoviruses aren’t deadly. Almost everyone has been infected with a reovirus, and almost no one gets sick, Dermody says. But if the first exposure to a food with gluten occurs during infection, the virus may…

Engineered immune cells boost leukemia survival for some

CAR-T cell attacking a leukemia cell
IMMUNE ATTACK Doctors can engineer a patient’s own immune cells to kill cancer cells. These engineered cells, called CAR-T cells, were effective for some people against relapses of leukemia over the long term. Here, a CAR-T cell (red) attacks a leukemia cell (yellow).

WASHINGTON — Immune cells engineered to hunt and destroy cancer cells may help some people with acute lymphoblastic leukemia (ALL) live much longer.

Outcomes depended upon disease severity before treatment, oncologist Jae Park reported April 3 at the American Association for Cancer Research annual meeting.

In ALL — expected to strike 5,970 people and kill 1,440 in the United States in 2017 — immune cells called B cells grow out of control in bone marrow and can spread to other tissues. Overall, five-year survival rates are 71 percent. But fewer than 10…