Clinical data has supported the early use of plasma in high ratios of plasma to red cells to patients in hemorrhagic shock. The benefit from plasma seems to extend beyond its hemostatic effects to include protection to the post-shock dysfunctional endothelium. Resuscitation of the endothelium by plasma and one of its major constituents, fibrinogen, involves cell surface stabilization of syndecan-1, a transmembrane proteoglycan and the protein backbone of the endothelial glycocalyx. The pathogenic role of miRNA-19b to the endothelium is explored along with the PAK-1-mediated intracellular pathway that may link syndecan-1 to cytoskeletal protection. Additionally, clinical studies using fibrinogen and cyroprecipitate to aid in hemostasis of the bleeding patient are reviewed and new data to suggest a role for plasma and its byproducts to treat the dysfunctional endothelium associated with nonbleeding diseases is presented.

Syndecan-1 is considered a biomarker of injury to the endothelial glycocalyx following hemorrhagic shock, with shedding of sdc1 deleterious. Resuscitation with fresh frozen plasma (FFP) has been correlated with restitution of pulmonary sdc1 and reduction of lung injury, but the precise contribution of sdc1 to FFPs protection in the lung remains unclear. Human lung endothelial cells were used to assess the time and dose dependent effect of FFP on sdc1 expression and the effect of sdc1 silencing on in vitro endothelial cell permeability and actin stress fiber formation. Wild-type (WT) and syndecan-1−/− mice were subjected to hemorrhagic shock followed by resuscitation with lactated ringers (LR) or FFP and compared to shock alone and shams. Lungs were harvested after 3 hours for analysis of permeability, histology, and inflammation and for measurement of syndecan- 2 and 4 expression. In vitro, FFP enhanced pulmonary endothelial sdc1 expression in time- and dose-dependent manners and loss of sdc1 in pulmonary endothelial cells worsened permeability and stress fiber formation by FFP. Loss of sdc1 in vivo lead to equivalency between LR and FFP in restoring pulmonary injury, inflammation, and permeability after shock. Lastly, sdc1 −/− mice demonstrated a significant increase in pulmonary syndecan 4 expression after hemorrhagic shock and FFP based resuscitation. Taken together, our findings support a key role for sdc1 in modulating pulmonary protection by FFP after hemorrhagic shock. Our results also suggest that other members of the syndecan family may at least be contributing to FFP’s effects on the endothelium, an area that warrants further investigation.

These data suggest that in-vitro, fibrinogen associated with cell surface syndecan-1 and enhanced endothelial barrier integrity.

Hemorrhagic shock results in systemic injury to the endothelium contributing to post-shock morbidity and mortality. The mechanism involves syndecan-1, the backbone of the endothelial glycocalyx. We have shown in a rodent model that lung syndecan-1 mRNA is reduced following hemorrhage, whereas the molecular mechanism underlying the mRNA reduction is not clear. In this study, we present evidence that miR-19b targets syndecan-1 mRNA to downregulate its expression. Our results demonstrate that miR-19b was increased in hemorrhagic shock patients and in-vitro specifically bound to syndecan-1 mRNA and caused its degradation. Further, hypoxia/reoxygenation (H/R), our in vitro hemorrhage model, increased miR-19b expression in human lung microvascular endothelial cells, leading to a decrease in syndecan-1 mRNA and protein. H/R insult and miR-19b mimic overexpression comparably exaggerated permeability and enhanced endothelial barrier breakdown. The detrimental role of miR-19b in inducing endothelial dysfunction was confirmed in vivo. Lungs from mice undergoing hemorrhagic shock exhibited a significant increase in miR-19b and a concomitant decrease in syndecan-1 mRNA. Pretreatment with miR-19b oligo inhibitor significantly decreased lung injury, inflammation, and permeability and improved hemodynamics. These findings suggest that inhibition of miR-19b may be a putative therapeutic avenue for mitigating post shock pulmonary endothelial dysfunction in hemorrhage shock.

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