Sepsis is not only one of the diseases of old people used to die before the discovery of antibiotics. It is still a major killer. Now, a new study shows that immune cells called B cells prevent sepsis in mice, a discovery that could help scientists design better treatments for the disease.
Each year, up to 1 million people in the US suffer from septicemia, a rampant infection associated with inflammation bodywide. Despite antibiotics and other treatments, approximately 25% of sepsis patients die, says the researcher of infectious diseases Steven Opal of Brown University, who was not involved in the study. "Sepsis is a huge problem that we had a lot of difficulty to solve," he said.
At first glance, the B cells do not look like part of the solution. Their most current work is pump defensive proteins called antibodies. Immunologist Filip Swirski of Harvard Medical School in Boston and colleagues found the involvement of cells in sepsis by accident. Swirski was probing the role of immune cells called macrophages in cardiovascular disease. He and his colleagues tried to identify the cells that make macrophage colony stimulating factor (GM-CSF). this protein has a great influence on white blood cells, which stimulates some of them to mature and start-up disease-fighters such as neutrophils. Swirski said researchers thought that macrophages or other non-B cells were the source of GM-CSF. However, in mice, the team found, most GM -CSF-producing cells in the spleen were B cells These cells, as innate lined researchers -B response activator cells (IRA) were unique. Their cell membrane bristling a combination of proteins not seen on other cells B. Furthermore, B cells generally detect microbes intrusion using the cell B receptor, a protein that is found only on their surface, while the IRA-B cells based on the same protein that are prevalent on macrophages and other cells of the body.
A situation where GM-CSF may be important is that sepsis studies conflict on whether it is harmful or beneficial. To measure the effects of IRA-B cells, the researchers studied mice who developed sepsis due to intestinal perforation. Mice that lacked B cells died, while 40% of control animals who had survived many cells, Swirski and his colleagues report online today in Science . The IRA-B cell "is a specialized manufacturer GM-CSF in the context of infection," says Swirski.
The study is not the first to suggest that B cells sepsis curb a published article last summer as this conclusion, but it did not identify the brand B cells offers the advantage or how they help. Swirski suggests that IRA-B cells prevent sepsis accelerating attack by neutrophils on pathogens, which therefore allows the immune system to the previous stop. IRA-B cells normally hang in the wall of the abdomen. But when they detect bacteria, they upset the spleen, where different types of immune cells mingle.
"They deliver a precise dose of GM-CSF where it is needed," says Swirski. a quick victory stimulated by the chemical may be important, he said, because "the immune system is a double-edged sword in sepsis: it is necessary to get rid of a bacterial infection, but it can cause enormous damage "for example, the inflammation caused by the immune system cells can lead to clotting. bloodshed that affects many patients with sepsis.
"It is a study quite remarkable, and quite surprising," said Opal. To move forward, he suggests, researchers must determine what range of pathogens of the IRA-B cell is working against and if they can use to fight against infections. Swirski and his colleagues have made a discovery encouraging, identifying IRA-B cells in people. In the future, the team suggests it might be possible to grow cultured cells and injecting them into patients or using drugs to stimulate replication in the body.
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