Proteomic analysis of protein changes in plasma by balloon test occlusion

Transient ischemia provides the tolerance against prolonged ischemia in the brain. In mouse experimental model, transient ischemia changes the composition ratio of circulating proteins, which associate with neuroprotection; however, the human evidence is lacking. Here we mimicked balloon test occlusion (BTO) of carotid artery as a transient ischemia and investigated the change of composition ratio of the circulating protein in the human plasma. We collected blood samples from nine patients (5 men and 4 women; mean age 64.2 years; range 45 to 77 years) before and 48 h after BTO and investigated the changes of circulating molecules level in the proteome using LC-MS/MS analysis. Leucine-rich alpha-2-glycoprotein and serum amyloid A-1 increased and protein AMBP decreased in the blood samples after BTO. Transient change of blood flow in the brain alters molecular expression in the plasma. Because the alteration of plasma protein composition is involved in ischemic tolerance in animal models, the proteins whose level was changed by BTO may be also involved in neuroprotection against ischemia in human.