The Proteolytic Inactivation of Protein Z-Dependent Protease Inhibitor by Neutrophil Elastase Might Promote the Procoagulant Activity of Neutrophil Extracellular Traps in Sepsis

Septic shock is the archetypal clinical setting in which extensive crosstalk between inflammation and coagulation dysregulates the latter. The main anticoagulant systems are systematically impaired, depleted, and/or downregulated. Protein Z-dependent protease inhibitor (ZPI) is an anticoagulant serpin that not only targets coagulation factors Xa and XIa but also acts as an acute phase reactant whose plasma concentration rises in inflammatory settings. The objective of the present study was to assess the plasma ZPI antigen level in a cohort of patients suffering from septic shock with or without overt-disseminated intravascular coagulation (DIC). The plasma ZPI antigen level was approximately 2.5-fold higher in the patient group (n = 100; 38 with DIC and 62 without) than in healthy controls (n = 31). The elevation's magnitude did not appear to depend on the presence/absence of DIC. Furthermore, Western blots revealed the presence of cleaved ZPI in plasma from patients with severe sepsis, independently of the DIC status. In vitro, ZPI was proteolytically inactivated by purified neutrophil elastase (NE) and by NE on the surface of neutrophil extracellular traps (NETs). The electrophoretic pattern of ZPI after NE-catalyzed proteolysis was very similar to that resulting from the clotting process-suggesting that the cleaved ZPI observed in severe sepsis plasma is devoid of anticoagulant activity. Taken as a whole, our results (1) suggest that NE is involved in ZPI inactivation during sepsis, and (2) reveal a novel putative mechanism for the procoagulant activity of NETs in immunothrombosis.

CAPS criteria fail to identify most severely-ill thrombotic antiphospholipid syndrome patients requiring intensive care unit admission

PURPOSE

Catastrophic antiphospholipid syndrome (CAPS), the most severe manifestation of antiphospholipid syndrome (APS), is characterised by simultaneous thromboses in multiple organs. Diagnosing CAPS can be challenging but its early recognition and management is crucial for a favourable outcome. This study was undertaken to evaluate the frequencies, distributions and ability to predict mortality of "definite/probable" or "no-CAPS" categories of thrombotic APS patients requiring admission to the intensive care unit (ICU).

METHODS

This French national multicentre retrospective study, conducted from January 2000 to September 2018, included all APS patients with any new thrombotic manifestation(s) admitted to 24 ICUs.

RESULTS

One hundred and thirty-four patients (male/female ratio: 0.4; mean age at admission: 45.4 ± 15.0 years), who experienced 152 CAPS episodes, required ICU admission. The numbers of definite, probable or no-CAPS episodes, respectively, were: 11 (7.2%), 60 (39.5%) and 81 (53.3%). No histopathological proof of microvascular thrombosis was the most frequent reason for not being classified as definite CAPS. Overall, 35/152 (23.0%) episodes were fatal, with comparable rates for definite/probable CAPS and no CAPS (23% vs. 28.8% respectively, p = 0.4). The Kaplan-Meier curve of estimated probability of survival showed no between-group survival difference (log-rank test p = 0.5).

CONCLUSIONS

In this study, CAPS criteria were not associated with mortality of thrombotic APS patients requiring ICU admission. Further studies are need evaluate the adequacy of CAPS criteria for critically-ill APS patients.