Urinary trypsin inhibitor attenuated inflammatory response of patients undergoing cardiopulmonary bypass by inducing activated Treg cells.

The urinary trypsin inhibitor (ulinastatin) is used in the clinic to prevent inflammatory responses in patients undergoing cardiopulmonary bypass (CPB); however, the anti-inflammatory mechanism is unclear. In the current study, we recruited 40 patients undergoing selective cardiac valve replacement surgery; and these patients were randomly divided into two groups (ulinastatin group [UG] and control group [CG]). We collected peripheral blood preoperatively, at the end of CPB, and postoperative days 1 and 3 and analyzed the kinetic changes in regulatory T (Treg) cell subsets. There was no statistically significant difference in the number of CD4(+) T cells between the two groups. The number of CD4(+)CD25(+) Treg cells, especially the suppressive activated Treg (aTreg) subset, was higher in the UG than the CG 1 and 3 days postoperatively. Thus, ulinastatin alleviated the inflammatory response during CPB by inducing the expansion of aTreg cells.