Low-grade endotoxemia and clotting activation in the early phase of pneumonia

Background and objective: Community-acquired pneumonia (CAP) is associated with an increased risk of arterial and venous thrombosis but the underlying pathophysiological mechanisms are still unclear. We investigated if, in patients with CAP, a pro-thrombotic state does exist and its relationship with serum levels of endotoxins. Methods: A total of 104 consecutive patients with CAP were prospectively recruited and followed up until discharge. At admission and at discharge, serum endotoxins, systemic markers of clotting activation and zonulin, a marker of gut permeability, were analysed. Hospitalized patients matched for gender, age and comorbidities but without infections were used as control. Results: At admission, CAP patients showed higher plasma levels of F1+2 , a marker of thrombin generation (P = 0.023), and lower levels of protein C (PC; P < 0.001) and activated PC (aPC) (P < 0.001) compared with controls. At discharge, plasma levels of both PC and aPC significantly increased while F1+2 significantly decreased (P < 0.001). Baseline serum endotoxins and zonulin were higher in CAP patients than controls (P < 0.001) and significantly decreased at discharge; a significant correlation between serum endotoxins and zonulin was detected (R = 0.575; P < 0.001) CONCLUSION: This study provides the first evidence that CAP patients disclose an ongoing pro-thrombotic state and suggests a role for endotoxemia in determining enhanced thrombin generation.