Monocyte Syk Phosphorylation as a Candidate Biomarker of Vasoplegic Shock After Cardiac Surgery with Cardiopulmonary Bypass: A Proof-of-Concept Observational Study

Source abstract

Abstract Background Vasoplegic shock after cardiac surgery with cardiopulmonary bypass (CPB) is a frequent complication associated with significant morbidity and mortality. The aim of this study was to identify candidate biomarkers of vasoplegic shock on the first postoperative day (POD 1) following cardiac surgery with CPB among three effector proteins of Fc receptor signalling: spleen tyrosine kinase (Syk), phospholipase C gamma (PLC-G) and Src homology 2 domain-containing phosphatase 1 (SHP-1), in monocytes and neutrophils. Methods Patients undergoing cardiac surgery with scheduled CPB without autoimmune disease or preoperative infection were included. The expression of phosphorylated Syk, PLC-G and SHP-1 in monocytes and neutrophils was measured by flow cytometry prior to (T0) and after (T1) CPB on PODs 1, 3 and 7. Associations between norepinephrine (NOR) use on POD 1 and protein fluorescence at T1 or T1/T0 ratios were assessed. Results Of the 23 patients analysed, four (17%) had NOR on POD 1. NOR on POD 1 was not associated with protein expression at T1. The T1/T0 ratio of Syk in monocytes was lower in patients without NOR on POD 1 (p = 0.032). The area under the ROC curve was 0.85 [0.60-1.00]; a threshold of 0.47 provided a sensitivity of 100% (95% CI 40–100) and a specificity of 74% (95% CI 49–91). This association did not remain significant after Bonferroni correction for the six comparisons performed (adjusted p = 0.19). Conclusions In this exploratory study, monocyte Syk phosphorylation status may represent a candidate biomarker of vasoplegic shock following cardiac surgery with CPB, warranting validation in an independent cohort.