legal alien. mitochondria own body can trigger an immune response.
Louisa Howard
There is a medical mystery. A man arrives in an emergency room of the hospital with a broken leg, and two days later he was burning with fever and her lungs are so inflamed that it needs a ventilator to breathe. It is as if he is fighting off a severe bacterial infection, yet it has no open wounds.
The doctors have seen this systemic inflammatory response syndrome of the situation called life threatening (SIRS) -PLAY dozens of times. Until recently, they believed that the shock of an injury such as a crushed leg or pelvic fracture, reduced blood flow to the intestine; which somehow gives the possibility of bacteria to migrate from the intestine into the blood through a main vein in the abdominal wall, known as the portal vein. Infected blood by bacteria from a condition known as sepsis can cause fever, inflammation and organ failure.
But in the early 190s, Frederick brothers and Ernest Moore, surgeons at the University of Colorado, Denver, placed the catheters in the veins doors trauma victims with SIRS and saw no bacteria. Experts now widely agree that these patients are not infected, leaving unexplained inflammation. "No one could find the source," says Carl Hauser, a trauma surgeon and immunologist surgeon at Harvard Medical School in Boston.
In a new study, Hauser and colleagues focused on plasma, colorless liquid in which blood cells are suspended. They took fluid samples from 15 severely injured patients who had just arrived in an urban emergency room. the samples contained a surprising amount of DNA. specifically, researchers have discovered-DNA the genetic material 1000 times mitochondrial belonging to power plants of the cell -. than that observed in normal plasma the data suggest, said Hauser, when many cells are damaged in a wound, they release a large amount of mitochondrial fragments in the blood. "it was a revelation for me."
the body responds to this mitochondrial DNA as if it is a bacterial invader. When the team exposed human neutrophil, the dominant type of white blood cell involved in the immune response of the body to bits mitochondria, immune cells launched the same chemical response they make when they spot foreign bacteria. In addition, when the researchers injected mitochondrial debris in the mouse abdominal wall, neutrophils swarmed the site. And rats, injection of mitochondrial debris in the bloodstream caused lung inflammation, reports the team in issue tomorrow Nature . Neutrophils were "treated mitochondria as an enemy," says Hauser.
The answer is logical. Neutrophils are programmed to recognize a group of molecules called formyl peptides, which are common in bacteria and other organisms celled. the problem is that mitochondria, which biologists think symbiotic bacteria were once also the awareness warning markers.
the findings could lead to better treatments for SIRS. inflammatory complications injury or illness account for about half of the patients in intensive care units, Hauser said, but antibiotics only work when the bacteria are to blame. He said that blocking the neutrophil response is already possible. but before doctors call off the attack of the body, he said, they need rapid tests, high accuracy for distinguishing inflammation induced mitochondria-the actual infection.
Frederick Moore, now at the Methodist Hospital Research Institute in Houston, Texas, agrees that the work provides a path to more effective treatment of systemic inflammation. "What clinicians face today is that they can only do one thing, which is to provide patients with broad-spectrum antibiotics," a strategy that is both costly and potentially dangerous, he said, because it grows resistant bacteria strains.
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