Dataset Information

Circulating histones are mediators of trauma-associated lung injury.

ABSTRACT:

Rationale

Acute lung injury is a common complication after severe trauma, which predisposes patients to multiple organ failure. This syndrome largely accounts for the late mortality that arises and despite many theories, the pathological mechanism is not fully understood. Discovery of histone-induced toxicity in mice presents a new dimension for elucidating the underlying pathophysiology.

Objectives

To investigate the pathological roles of circulating histones in trauma-induced lung injury.

Methods

Circulating histone levels in patients with severe trauma were determined and correlated with respiratory failure and Sequential Organ Failure Assessment (SOFA) scores. Their cause-effect relationship was studied using cells and mouse models.

Measurements and main results

In a cohort of 52 patients with severe nonthoracic blunt trauma, circulating histones surged immediately after trauma to levels that were toxic to cultured endothelial cells. The high levels were significantly associated with the incidence of acute lung injury and SOFA scores, as well as markers of endothelial damage and coagulation activation. In in vitro systems, histones damaged endothelial cells, stimulated cytokine release, and induced neutrophil extracellular trap formation and myeloperoxidase release. Cellular toxicity resulted from their direct membrane interaction and resultant calcium influx. In mouse models, cytokines and markers for endothelial damage and coagulation activation significantly increased immediately after trauma or histone infusion. Pathological examinations showed that lungs were the predominantly affected organ with edema, hemorrhage, microvascular thrombosis, and neutrophil congestion. An anti-histone antibody could reduce these changes and protect mice from histone-induced lethality.

Conclusions

This study elucidates a new mechanism for acute lung injury after severe trauma and proposes that circulating histones are viable therapeutic targets for improving survival outcomes in patients.

SUBMITTER: Abrams ST

PROVIDER: S-EPMC3570656 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:The etiology of trauma-hemorrhage shock-induced acute lung injury has been difficult to elucidate due, at least in part, to the inability of in vivo studies to separate the non-injurious pulmonary effects of trauma-hemorrhage from the tissue injurious ones. To circumvent this in vivo limitation, we utilized a model of trauma-hemorrhagic shock (T/HS) in which T/HS-lung injury was abrogated by dividing the mesenteric lymph duct. In this way, it was possible to separate the pulmonary injurious response from the non-injurious systemic response to T/HS by comparing the pulmonary molecular response of rats subjected to T/HS which did and did not develop lung injury as well as to non-shocked rats. Utilizing high-density oligonucleotide arrays and treatment group comparisons of whole lung tissue collected at 3 hours after the end of the shock or sham-shock period, 139 of the 8,799 assessed genes were differentially expressed. Experiment Overall Design: Four groups of rats (n=3) were studied in order to identify changes in pulmonary gene expression associated with T/HS, both in the presence and absence of lung injury. These included trauma-sham shock (T/SS) rats which had a laparotomy (trauma) but were not subjected to hemorrhagic shock. These rats had no lung injury and served as controls for rats which were subjected to T/HS (laparotomy plus 90 min of shock) and had lung injury. Differences in gene expression between these two groups would represent both the effects of hemorrhagic shock as well as lung injury. To distinguish the gene response of hemorrhagic shock from the gene response associated with lung injury, gene expression was also compared between T/HS rats (hemorrhage and lung injury) and rats subjected to T/HS plus lymph duct ligation (T/HS-LDL), since the T/HS-LDL rats experienced hemorrhagic shock but had no measurable lung injury. Lastly, to identify hemorrhagic shock- modified genes, the pulmonary gene response of T/HS-LDL (hemorrhage without lung injury) were compared to rats subjected to T/SS plus LDL (no hemorrhage or lung injury). Three hours after the end of the 90 min shock or sham-shock period (i.e. 4.5 hrs after the induction of T/HS), the rats were sacrificed and specimens harvested for genechip analysis and histology.