The Molecular Relationship Between SDF4 and Thiol/Disulfide Homeostasis and Cardiac Injury Markers in Serum and Pericardial Fluid of Patients Undergoing Open-Heart Surgery

<b>Background/Objectives</b>: Various pathophysiological mechanisms play a role in the development of cardiovascular diseases (CVDs). There is a need for new biomarkers that can complement existing clinical findings, particularly in the early diagnosis and prognostic assessment of coronary artery disease (CAD) and that can also contribute to more effective management of the diagnosis and treatment process. Therefore, both blood and pericardial fluid samples can provide important diagnostic information. This study aims to investigate Stromal Cell-Derived Factor 4 (SDF4) levels and thiol/disulfide homeostasis in the blood and pericardial fluid of patients with established CAD undergoing open-heart surgery with cardiopulmonary bypass (CPB), in order to better characterize oxidative stress-related and redox-mediated pathophysiological processes associated with the development and progression of coronary heart disease. Comparisons with a healthy control group were performed to elucidate disease-related biochemical alterations rather than to propose these markers as diagnostic tools for CAD. <b>Methods</b>: In this study, intraoperatively collected venous blood and pericardial fluid samples from 45 patients undergoing on-pump coronary artery bypass grafting were analyzed. SDF4 levels were measured using enzyme-linked immunosorbent assay (ELISA), while thiol-disulfide homeostasis was assessed via spectrophotometric analysis. <b>Results</b>: The study revealed statistically significant differences in parameters such as SDF-4, native thiol, total thiol, disulfide, and disulfide/total thiol ratio among the control, patient serum, and pericardial fluid groups (<i>p</i> < 0.05). Notably, SDF-4 and disulfide levels were elevated, while thiol levels were reduced in the pericardial fluid group, suggesting increased oxidative stress and disrupted redox balance. Principal Component Analysis (PCA) and Variable Importance in Projection (VIP) analyses successfully demonstrated the discriminative power of these parameters among the groups. <b>Conclusions</b>: The increased SDF-4 levels and disturbances in the thiol-disulfide balance observed in this study indicate elevated oxidative stress and impaired cellular redox homeostasis in CAD. These findings suggest that SDF-4 and thiol-disulfide parameters may serve as important biochemical markers in the pathophysiology of CVD and hold potential as diagnostic and prognostic biomarkers.