Bariatric surgery in morbidly obese individuals affects plasma levels of protein C and thrombomodulin

Obesity is associated with a prothrombotic milieu and an increased risk for thrombotic events. Bariatric surgery is the most effective treatment for obesity resulting in dramatic weight loss and reduced inflammation and extrinsic coagulation pathway activation. Blood samples were drawn from 60 patients undergoing Roux-en-Y gastric bypass surgery before and 1 year after the intervention. Protein C (PC), activated PC (APC), soluble thrombomodulin (TM), soluble E-selectin (E-Sel), prothrombin time (PT) and activated partial thromboplastin time (aPTT) were evaluated. Both PC (187.4 ± 64.5% before surgery to 118.1 ± 48% 1 year after surgery, p < 0.001) and APC (138.7 ± 64.4% before surgery to 69.1 ± 65.7% after surgery, p < 0.001) were reduced following surgical intervention. TM showed a similar behavior with a reduction of soluble TM after the procedure from 5.7 ± 2.6 to 3.2 ± 1.4 ng/ml (p < 0.001). Similarly, soluble E-Sel was reduced after surgery from 26.6 ± 12.7 to 5.5 ± 4.1 ng/ml (p < 0.001). In contrast, aPTT was not shortened but slightly increased from 29.1 ± 4.8 s. before surgery to 31 ± 4.4 s. (p = 0.001) after surgery and levels of PT were reduced after surgery to 89.6 ± 15.5% from an initial 97.5 ± 13.5% (p < 0.001). In conclusion, we demonstrate a reduction of PC and APC 1 year after bariatric surgery accompanied by a reduction in soluble TM and soluble E-Sel. The reduction of PC and APC is not paralleled by a reduction but in contrast by a prolongation of aPTT suggesting a compensatory upregulation of PC during obesity. The reduction of TM and E-Sel might hint towards an improved endothelial function in this cohort of patients.