Pharmacological modulation of procoagulant microparticles improves haemodynamic dysfunction during septic shock in rats

Abstract

Circulating microparticles play a pro-inflammatory and procoagulant detrimental role in the vascular dysfunction of septic shock. It was the objective of this study to investigate mechanisms by which a pharmacological modulation of microparticles could affect vascular dysfunction in a rat model of septic shock. Septic or sham rats were treated by activated protein C (aPC) and resuscitated during 4 hours. Their microparticles were harvested and inoculated to another set of healthy recipient rats. Haemodynamic parameters were monitored, circulating total procoagulant microparticles assessed by prothrombinase assay, and their cell origin characterised. Mesenteric resistance arteries, aorta and heart were harvested for western blotting analysis. We found that a) the amount and phenotype of circulating microparticles were altered in septic rats with an enhanced endothelial, leucocyte and platelet contribution; b) aPC treatment significantly reduced the generation of leucocyte microparticles and norepinephrine requirements to reach the mean arterial pressure target in septic rats; c) Microparticles from untreated septic rats, but not from aPC-treated ones, significantly reduced the healthy recipients' mean arterial pressure; d) Microparticle thromboxane content and aPC activity were significantly increased in aPC-treated septic rats. In inoculated naïve recipients, microparticles from aPC-treated septic rats prompted reduced NF-κB and cyclooxygenase-2 arterial activation, blunted the generation of pro-inflammatory iNOS and secondarily increased platelet and endothelial microparticles. In conclusion, in this septic shock model, increased circulating levels of procoagulant microparticles led to negative haemodynamic outcomes. Pharmacological treatment by aPC modified the cell origin and levels of circulating microparticles, thereby limiting vascular inflammation and favouring haemodynamic improvement.

Thrombomodulin favors leukocyte microvesicle fibrinolytic activity, reduces NETosis and prevents septic shock-induced coagulopathy in rats

“…Interestingly, besides its direct and expected anticoagulant effects, this is the first report showing that rhTM limits the release of MVs and thereby coagulation supported by their procoagulant surface. These observations are consistent with previously reported data from the laboratory demonstrating that recombinant human activated protein C reduces the generation of procoagulant endothelial and platelet MVs in CPL rats [ 23 ]. In sepsis, MVs stand as surrogate markers of blood cell activation and of the procoagulant and pro-inflammatory endothelial state [ 23 , 30 ].…”

“…These observations are consistent with previously reported data from the laboratory demonstrating that recombinant human activated protein C reduces the generation of procoagulant endothelial and platelet MVs in CPL rats [ 23 ]. In sepsis, MVs stand as surrogate markers of blood cell activation and of the procoagulant and pro-inflammatory endothelial state [ 23 , 30 ]. Interestingly, in the present study, we provide the first evidence that rhTM dramatically enhances (fivefold increase) the proportion of MVs bearing fibrinolytic activity in septic rats, while reducing total MVs by only 50%.…”

“…Rats underwent cecal ligation and puncture (CLP) as previously described [ 23 ]. First, rats were anesthetized with 1–2% isoflurane (Baxter S.A.S, Maurepas, France) and analgesia was ensured by Vetergesic ® (0.1 mg/kg of body weight; Sogeval).…”

“Immunonutrition” Has Failed to Improve Peritonitis-Induced Septic Shock in Rodents

“…On the 4 th day (after 72 hours of enteral nutrition), CLP rats underwent cecal ligation and puncture as previously described [ 32 ]. The operator was blinded concerning the allocated enteral nutrition.…”

Circulating Microparticles Alter Formation, Structure and Properties of Fibrin Clots

“…MPs are present in the blood under physiological conditions, but the level of circulating MPs is elevated in vascular, infectious, and immune-mediated pathologies 11 12 13 14 15 16 . MPs are heterogeneous in size, composition, density, and cellular origin.…”