When a bacterial infection rages out of control and courses through the blood stream, the immune system can fight so hard that it throws the body into septic shock. Now there may be a new treatment on the horizon to prevent this self-defeating onslaught. By calming down one of the hyped-up immune warriors, researchers prevented mice with massive infections from dying of septic shock.
Septic shock can sometimes be treated with antibiotics, but it still kills up to half its victims--about 50,000 in the United States each year. The problem starts when bacteria from an infected wound or an internal injury invade the blood stream and spit out bacterial toxins. The immune system furiously churns out proteins called cytokines that direct the immune system's fight against the infection, but the sheer numbers can cause such severe inflammation that blood pressure drops and major organs begin to shut down.
In an attempt to control the body's overzealous immune response, a team led by infectious disease specialist Thierry Calandra of Vaudois Hospital Center in Laussanne, Switzerland, focused on a cytokine called macrophage migration inhibitory factor (MIF) that inflame infected tissues during septic shock. They induced septic shock in mice and then injected some of them with antibodies to MIF. Untreated, only 31% of the mice survived, but 81% of those given MIF antibodies survived, the researchers report in the February Nature Medicine.
MIF may not turn out to be the most important culprit responsible for septic shock syndrome, cautions Thomas Martin of the University of Washington in Seattle, but he says that antibodies against MIF are "a new player that needs to be tested in humans."