Soluble ST2 Protein in Cardiac Surgery: A Possible Negative Feedback Loop to Prevent Uncontrolled Inflammatory Reactions

Background: Recent reports have demonstrated that cardiopulmonary bypass (CBP) utilization leads to a TH2 cytokine bias in patients undergoing coronary artery bypass grafting (CABG) operation. The relation of soluble ST2 and secretion of IL-10, markers of TH2 T-cell activation, and IL-13 in relation to immunoglobulin isotope production is not known in patients undergoing On- versus Off-pump (CABG) procedure.

Methods: 30 patients were prospectively included in the study (On- vs Off-pump CABG, each n = 15). Serum samples were obtained prior to, and 30 min, 60 min and 24hrs after operation. ELISA was utilized to detect sST2 and IL-10, IL-13 and immunoglobulin isotype production.

Results: In both cohorts we could demonstrate a significant rise of ST2 24 hours after the CABG procedure. In the On-pump group ST2 levels (pg/ml) before the operation, at 30 and 60 minutes and after 24 hours were 115.3 +/- 25, 71.2 +/- 15, 114.1 +/- 26 and 4231.9 +/- 520, respectively. In the Off-pump group they were 200.3 +/- 109, 91.2 +/- 20, 137 +/- 29 and 4144.9 +/- 488 (both, p < 0.0001, p < 0.0001, respectively). IL-10 (pg/ml) levels rose from preoperative values of 6.2 +/- 1.6 in the On-pump group and 7.91 +/- 1.8 in the Off-pump group to 33.14 +/- 8.7 and 13.72 +/- 3 after 60 minutes (p 0.0189, p 0.0397, respectively). IL-13 levels and immunoglobulin production did not change significantly within the study period irrespective of the operation procedure used.

Conclusion: In conclusion, our results demonstrate that sST2 and IL-10, markers of TH2 cytokine producing cells, are increased in CABG operation, irrespective of the procedure selected, and settles a longstanding controversy concerning the shift from Th1 to Th2 cells.