Systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS) are the major causes of death in patients with acute aortic syndrome (AAS). Therefore, the prevention of SIRS and MODS is of great clinical value, and immunomodulatory therapy with thymosin alpha 1 may be beneficial. This study was designed to test the hypothesis that the administration of thymosin alpha 1 during the acute phase of AAS will result in a reduced incidence of SIRS and MODS.

Inclusion Criteria:

• The patients are conformed to 2010 ACC/AHA guidelines for the diagnosis and treatment of thoracic aortic disease (TAD) within two weeks of onset;
• Patients with acute aortic syndrome confirmed clinically and radiologically and planning to undergo emergency surgery were enrolled.
• The patients' age between 18 ~90 years old.
• Agree to participate in the study and sign the informed consent.

Exclusion Criteria:

• Patients allergic to Thymosin α1;
• Lactating women and pregnant women;
• Patients with mental diseases, drug and alcohol dependence;
• Refuse to participate in this study and refuse to sign the informed consent.