Newly Developed Recombinant Antithrombin Protects the Endothelial Glycocalyx in an Endotoxin-Induced Rat Model of Sepsis

Abstract

(1) Background: The endothelial glycocalyx is a primary target during the early phase of sepsis. We previously reported a newly developed recombinant non-fucosylated antithrombin has protective effects in vitro. We further evaluated the effects of this recombinant antithrombin on the glycocalyx damage in an animal model of sepsis. (2) Methods: Following endotoxin injection, in Wistar rats, circulating levels of hyaluronan, syndecan-1 and other biomarkers were evaluated in low-dose or high-dose recombinant antithrombin-treated animals and a control group (n = 7 per group). Leukocyte adhesion and blood flow were evaluated with intravital microscopy. The glycocalyx was also examined using side-stream dark-field imaging. (3) Results: The activation of coagulation was inhibited by recombinant antithrombin, leukocyte adhesion was significantly decreased, and flow was better maintained in the high-dose group (both p < 0.05). Circulating levels of syndecan-1 (p < 0.01, high-dose group) and hyaluronan (p < 0.05, low-dose group; p < 0.01, high-dose group) were significantly reduced by recombinant antithrombin treatment. Increases in lactate and decreases in albumin levels were significantly attenuated in the high-dose group (p < 0.05, respectively). The glycocalyx thickness was reduced over time in control animals, but the derangement was attenuated and microvascular perfusion was better maintained in the high-dose group recombinant antithrombin group (p < 0.05). (4) Conclusions: Recombinant antithrombin maintained vascular integrity and the microcirculation by preserving the glycocalyx in this sepsis model, effects that were more prominent with high-dose therapy.

Endothelial glycocalyx degradation during sepsis: Causes and consequences

“…Antithrombin is a known physiologic anticoagulant whose activity is accentuated by binding of heparan sulfate from the endothelial glycocalyx [69] . In a rat model of sepsis, recombinant antithrombin was shown to decrease leukocyte adhesion, reduce parameters of DIC, lower circulating syndecan-1 and hyaluronan levels, and inhibit glycocalyx destruction [126] . In a canine shock model, unfractionated heparin in combination with standard care reduced glycocalyx shedding when compared to standard care alone [127] .…”

Protection and rebuilding of the endothelial glycocalyx in sepsis – Science or fiction?

“…Gao [76] 2015 - male Sprague-Dawley rats - electron microscopy - ELISA Hydrocortisone stabilizes eGC and reduces HS and SDC-1 levels and improves intestinal perfusion in severe acute pancreatitis . T. Iba [79] 2021 - rats (Wistar) - IVM (leukocyte adhesion, SDF) - ELISA AT-γ ameliorates LPS -induced impairment of microcirculation with decrease of PBR and reduction of SDC-1 and hyaluronan levels. S. Han [87] 2016 - C57BL/6J mice - Ang1 flox/flox mice - Ang2 flox/flox mice - Tie2 flox/flox mice - cell culture - IVM (FITC-dextran 40kDa) - immunofluorescence - Evans blue dye extravasation technique Administration of ABTAA (Angpt-2 binding and Tie2 activating antibody) improves survival in LPS , CLP and S. aureus sepsis model, reduces leakage and production of inflammatory cytokines, prevents shedding of HS and perlecan and reduces heparanase density in lung and kidney tissue.…”

“…Nonetheless, further studies are needed to decode the complex interplay between coagulation and the eGC. For example, Iba et al could recently observe less syndecan-1 and hyaluronan shedding, as well as preservation of glycocalyx thickness (PBR method) after administration of recombinant antithrombin in LPS-treated rats [79] .…”

Antithrombin and Its Role in Host Defense and Inflammation

“…In a rat model challenged with intravenous endotoxin administration, concomitant treatment with a newly developed recombinant AT preparation reduced circulating levels of syndecan-1 and hyaluronan, both components of the glycocalyx. Intravital microscopy revealed a thicker glycocalyx in treated animals, which also had better microvascular perfusion and lower systemic lactate levels [78]. Administration of…”