The cells of blood coagulation called platelets are generally good, stanching wounds so that we not bleed to death. But for people with lupus, the cells are wicked that aggravate the disease, according to a new study. The work also suggests that a commonly prescribed anticoagulant medication for patients with heart disease could ease the symptoms of lupus.
In lupus, the immune system produces antibodies that target the patient's own cells, which causes joint pain, skin lesions, fatigue, and other symptoms. The blood of lupus is often prone to clotting, and they are more susceptible to heart attack and stroke. These symptoms indicate that platelets play a role in the disease.
immunologist Patrick Blanco of the University of Bordeaux in France and his colleagues wondered if another link platelet could come from a rare breed of warrior immune system known as dendritic cell plasmacytoid name (pDCs). In the bloodstream, pDCs release chemical messengers called type I interferons that rev up the immune system. the lupus patients are too interferon type I, which stimulates the production of auto-antibodies attack causing symptoms. Platelets, in turn, the production of a protein called CD154 that turns on pDCs, and so they could indirectly increase interferon type I output.
To determine if platelets exacerbate lupus pDCs by triggering the immune system to overactivate, Blanco and colleagues from healthy people with blood platelets of patients with lupus mixed. Small balls of antibodies present in the blood of lupus glommed on platelets and on. Activated platelets are CD154, the researchers found, and turn on pDCs, causing them to pump four times the normal amount of a type I interferon In a lupus patient, which could cause the immune system to ramp up his attacks on the body's cells. The team reports its findings online today in Science Translational Medicine .
If switched on platelets worsen lupus, closed cells could alleviate the symptoms of the disease. Thus, researchers dosed mice with lupus imitating clopidogrel (Plavix), a drug that counteracts clotting by preventing platelet activation. In a strain of mice, the clopidogrel curbed the amount of damage to the kidneys, a common consequence and sometimes fatal disease. The compound has also boosted the survival in this strain and another variety of mouse lupus imitating. Blanco said that the platelets are doubly destructive in lupus, the rise of autoimmune attacks and produce potentially fatal clots. So, clopidogrel could be doubly beneficial, he said. His group plans to launch a drug test, which was approved for use in people for more than a decade, patients with lupus.
Mary Crow, an immunologist and rheumatologist at the Hospital for Special Surgery in New York accepts the results. "I think all that platelets play a role" in promoting lupus symptoms, she said. But the work does not convince rheumatologist Lars R ö nnblom of Uppsala University Sweden. He notes, for example, that clopidogrel helped a type of lupus mice mimicking even if the animals are not high levels of type I interferons This suggests that platelets do not necessarily have worse by lupus pDCs prodding, he says, but it does not exempt.
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