Comparison of the Effects of Subcutaneous Versus Continuous Infusion of Heparin on Key Inflammatory Parameters Following Sepsis

Nonbacterial thrombotic endocarditis in a patient with primary antiphospholipid syndrome

Nonbacterial thrombotic endocarditis (NBTE) is described in patients with mucin-producing cancers and connective tissue disorders (usually SLE). We report NBTE in the setting of primary antiphospholipid antibody syndrome (APS). A 65-year-old female with APS was incidentally found to have thickened mitral leaflets on transthoracic echocardiogram with no signs of infection. Transesophageal echocardiogram (TEE) showed a mobile mitral mass (1.4 × 0.7 cm) and moderate mitral regurgitation. Differential diagnoses included bacterial endocarditis, NBTE, thrombus or tumor. Given the history of primary APS, the absence of fever and negative blood cultures, NBTE was considered. Low-molecular-weight heparin, hydroxychloroquine and corticosteroid were initiated. Repeat TEE in a week revealed shrinkage of the mass (0.6 × 0.7 cm), indicating an inflammatory nature. Lifelong anticoagulation is indicated regardless of embolism occurrence. Hydroxychloroquine and corticosteroids may have roles in the treatment. Determining and treating the underlying etiology is important.

Phosphatidylserine-mediated platelet clearance by endothelium decreases platelet aggregates and procoagulant activity in sepsis

The mechanisms that eliminate activated platelets in inflammation-induced disseminated intravascular coagulation (DIC) in micro-capillary circulation are poorly understood. This study explored an alternate pathway for platelet disposal mediated by endothelial cells (ECs) through phosphatidylserine (PS) and examined the effect of platelet clearance on procoagulant activity (PCA) in sepsis. Platelets in septic patients demonstrated increased levels of surface activation markers and apoptotic vesicle formation, and also formed aggregates with leukocytes. Activated platelets adhered were and ultimately digested by ECs in vivo and in vitro. Blocking PS on platelets or αvβ3 integrin on ECs attenuated platelet clearance resulting in increased platelet count in a mouse model of sepsis. Furthermore, platelet removal by ECs resulted in a corresponding decrease in platelet-leukocyte complex formation and markedly reduced generation of factor Xa and thrombin on platelets. Pretreatment with lactadherin significantly increased phagocytosis of platelets by approximately 2-fold, diminished PCA by 70%, prolonged coagulation time, and attenuated fibrin formation by 50%. Our results suggest that PS-mediated clearance of activated platelets by the endothelium results in an anti-inflammatory, anticoagulant, and antithrombotic effect that contribute to maintaining platelet homeostasis during acute inflammation. These results suggest a new therapeutic target for impeding the development of DIC.