Factor VII-Activating Protease Is Activated in Multiple Trauma Patients and Generates Anaphylatoxin C5a

Abstract

Severe tissue injury results in early activation of serine protease systems including the coagulation and complement cascade. In this context, little is known about factor VII-activating protease (FSAP), which is activated by substances released from damaged cells such as histones and nucleosomes. Therefore, we have measured FSAP activation in trauma patients and have identified novel FSAP substrates in human plasma. Mass spectrometry-based methods were used to identify FSAP binding proteins in plasma. Anaphylatoxin generation was measured by ELISA, Western blotting, protein sequencing, and chemotaxis assays. Plasma samples from trauma patients were analyzed for FSAP Ag and activity, nucleosomes, C5a, and C3a. Among others, we found complement components C3 and C5 in FSAP coimmunoprecipitates. C3 and C5 were cleaved by FSAP in a dose- and time-dependent manner generating functional C3a and C5a anaphylatoxins. Activation of endogenous FSAP in plasma led to increased C5a generation, but this was not the case in plasma of a homozygous carrier of Marburg I single nucleotide polymorphism with lower FSAP activity. In multiple trauma patients there was a large increase in circulating FSAP activity and nucleosomes immediately after the injury. A high correlation between FSAP activity and C5a was found. These data suggest that activation of FSAP by tissue injury triggers anaphylatoxin generation and thereby modulates the posttraumatic inflammatory response in vivo. A strong link between C5a, nucleosomes, and FSAP activity indicates that this new principle might be important in the regulation of inflammation.

Circulating Factor VII Activating Protease (FSAP) Is Associated With Clinical Outcome in Acute Coronary Syndrome

“…32, 33 In our results, plasma FSAP concentrations did not return to baseline levels for 5 days after AMI. These findings are similar to our recent observations that in multi-trauma patients there is a massive activation of FSAP, which returns to the baseline level after 48 h. 34 Some studies have reported that inflammatory markers, including interleukin-6 and CRP, are increased significantly in the acute phase of ACS, 35 and remain increased until a few weeks after myocardial infarction. FSAP antigen expression in monocytes is increased by interleukin-6 in vitro, 13 so this could be the reason for the sustained FSAP expression in monocytes.…”

“…Finally, we have recently demonstrated that activation of FSAP is linked to the generation of the anaphylatoxin C5a, which is also a prominent pro-inflammatory factor. 34 Through these different mechanisms, FSAP may be involved in the destabilization of the atherosclerotic plaque during ACS. The production of FSAP by activated cells within the atherosclerotic lesion and its release into the extracellular matrix appear to be strongly linked to the local inflammatory process occurring within the arterial wall.…”

DNA and factor VII–activating protease protect against the cytotoxicity of histones

“…[35][36][37] We therefore wondered whether free histones circulate in sepsis. We set up an assay to specifically precipitate nucleosomes or free histones from serum.…”

“…In vivo, FSAP activation correlated with circulating nucleosomes and disease severity and mortality in patients with inflammatory conditions including severe sepsis, septic shock, and, specifically, meningococcal sepsis. [35][36][37] Because FSAP is activated upon incubation with cytotoxic histones and is able to degrade histone H1 and H3, we aimed to investigate its effects on histone-induced cytotoxicity. Furthermore, given that histones are part of nucleosomes in the nucleus, we aimed to compare the cytotoxicity of free histones and nucleosomes and determine their respective levels in the circulation in inflammatory disease.…”

Pullulan-histone antibody nanoconjugates for the removal of chromatin fragments from systemic circulation

“…Elevated levels of circulating Cfs has been reported in several disease conditions that have included auto-immune disorders [6], and a wide variety of acute and chronic human pathologies, such as severe infection [7], sepsis [8], trauma [9], diabetes [10], stroke [11] and renal failure [10]. Elevated levels of Cfs have been consistently reported in cancer [12,13], and the levels rise dramatically immediately following chemo-or radiotherapy [14e 17].…”