Heart attacks that occur at night are less severe than those that strike during the day. A new study headed by researchers at the Centro Nacional de Investigaciones Cardiovasculares (CNIC) and at Yale University School of Medicine, has explained why. Andrés Hidalgo, PhD and colleagues found that neutrophils have an internal clock that regulates their aggressiveness throughout the day and determines the extent of damage they cause to the heart after a heart attack. Studies by the international research team suggest that inhibiting these fluctuations could prevent neutrophils from causing excessive tissue damage during daylight hours, a phenomenon that may underlie the fact that heart attacks in the early morning are more damaging than heart attacks suffered at night. The researchers also developed a pharmacological strategy—using a drug called ATI2341—that in experimental models blocked the clock in neutrophils, keeping them in a “nighttime” state and thereby reducing their harmful potential during a heart attack. ATI2341 targets a receptor on the surface of neutrophils and switches the cells into the less active mode usually only seen at night. Protection against blood vessel occlusion in animals with sickle cell anemia after treatment with circadian clock inhibitors. Vessel walls are shown as white lines, neutrophils in yellow, and red blood cells trapped by neutrophils in red. [CNIC / Lidiane Torres]“Our study demonstrates that pharmacological delivery of a drug that activates a receptor on the surface of neutrophils induces their transition to a night-like, permissive state that alleviates the inflammatory response without interfering with…
