complete-partial-aortic-occlusion-for-treatment-hemorrhagic-shock

Complete and Partial Aortic Occlusion for the Treatment of Hemorrhagic Shock in Swine

Hemorrhage remains the leading cause of preventable deaths in trauma. Endovascular management of non-compressible torso hemorrhage has been at the ...

University of Michigan

Production of innate and adaptive immune cells from hematopoietic stem cells, and maturation of T lymphocytes are effective immune responses to fight severe microbial infection. In sepsis, this emergency myelopoiesis is damaged, leading to failure of bacterial clearance, and excessive stress-induced steroids cause immature T-lymphocyte apoptosis in thymus. We recently found that Cl-amidine, a peptidylarginine deiminase (PAD) inhibitor, improves survival in a mouse model of cecal ligation and puncture (CLP)-induced septic shock. In the present study we investigated how Cl-amidine promotes survival, focusing on protective effects of Cl-amidine on immune response. We confirmed survival-improving effect of Cl-amidine and are the first to explore the role of Cl-amidine in immune response. CLP caused bone marrow (BM) and thymus atrophy, decreased innate immune cells in BM. CLP increased levels of cytokines (IL-1β, IL-6, and TNF-α) and bacteria load in blood/liver. In primary splenocyte culture, lipopolysaccharide increased TNF-α production. In contrast, Cl-amidine attenuated these CLP and lipopolysaccharide-induced alterations. Moreover, Cl-amidine increased circulating monocytes. Collectively, our results demonstrate Cl-amidine plays protective roles by significantly decreasing BM and thymus atrophy, restoring innate immune cells in BM, increasing blood monocytes and blood/liver bacteria clearance, and attenuating pro-inflammatory cytokine production in a murine model of lethal sepsis.

Protective effect of Cl-amidine against CLP-induced lethal septic shock in mice.

Current biomarkers for sepsis are limited by their non-specificity, short half-life, and insensitive response to therapy. Recently, we have demonstrated that citrullinated histone H3(CitH3) is released into the blood from neutrophil extracellular traps(NETs) in response to severe infection, and CitH3 may be a potential biomarker for sepsis. In the present study, we found that NET components were released in mouse models of both lipopolysaccharide(LPS)-induced shock (LPSS) and hemorrhagic shock (HS). To further quantify CitH3 in the NETs, we established a CitH3 specific enzyme-linked immunosorbent assay. Circulating CitH3 was found to be elevated only in LPSS but not in HS. Importantly, blood CitH3 was detected 30 minutes after LPS insult, and remained elevated for 24 hours (period of the highest mortality). Treatment of endotoxic mice with YW3-56, a peptidylarginine deiminase-2/4 inhibitor, significantly diminished levels of CitH3 in the blood. Interleukin-1β did not respond to LPS early, and interleukin-1β and interleukin-6 fluctuated although they responded to treatment. Procalcitonin reacted to LPS insult late. Compared to CitH3, these biomarkers were non-specifically induced in LPSS and HS. Collectively, our results demonstrate that YW3-56 protects animals from LPSS, and CitH3 is a reliable biomarker due to its early appearance, specificity, duration, and response to therapeutic intervention.

CitH3: a reliable blood biomarker for diagnosis and treatment of endotoxic shock.

Immune cell death caused by neutrophil extracellular traps (NETs), referred to as NETosis, can contribute to the pathogenesis of endotoxemia and organ damage. Although the mechanisms by which infection induces NETosis and how that leads to organ dysfunction remain largely unknown, NET formation is often found following citrullination of histone H3 (CitH3) by peptidylarginine deiminase (PAD). We hypothesized that lipopolysaccharide (LPS)-induced activation of PAD and subsequent CitH3-mediated NET formation increases endothelial permeability and pulmonary dysfunction and, therefore, that inhibition of PAD can mitigate damage and improve survival in lethal endotoxemia. Here, we showed that treatment with YW3-56, a PAD2/PAD4 inhibitor, significantly diminished PAD activation, blocked LPS-induced pulmonary vascular leakage, alleviated acute lung injury, and improved survival in a mouse model of lethal LPS-induced endotoxemia. We found CitH3 in the bloodstream 30 min after intraperitoneal injection of LPS (35 mg/kg) into mice. Additionally, CitH3 production was induced in cultured neutrophils exposed to LPS, and NETs derived from these LPS-treated neutrophils increased the permeability of endothelial cells. However, YW3-56 reduced CitH3 production and NET formation by neutrophils following LPS exposure. Moreover, treatment with YW3-56 decreased the levels of circulating CitH3 and abolished neutrophil activation and NET formation in the lungs of mice with endotoxemia. These data suggest a novel mechanism by which PAD-NET-CitH3 can play a pivotal role in pulmonary vascular dysfunction and the pathogenesis of lethal endotoxemia.

Inhibition of peptidylarginine deiminase alleviates LPS-induced pulmonary dysfunction and improves survival in a mouse model of lethal endotoxemia.

We have found earlier that Tubastatin A (TubA), a selective inhibitor of histone deacetylase 6 (HDAC6), improves survival in a mouse model of lethal cecal ligation and puncture (CLP)-induced sepsis. However, the underlying mechanisms have not been fully established. This study sought to test the hypothesis that TubA could affect both lung and splenic functions. C57BL/6J mice were subjected to CLP, and randomized to receive either TubA (70 mg/kg) dissolved in dimethyl sulfoxide (DMSO), or DMSO alone, 1 h following CLP. Sham animals acted as control. Twenty-four hours later, lung tissue was harvested for pathological examination, and splenic tissue was harvested for bacterial colonization. In a parallel study, the spleen was collected 48 h following CLP, and single cell suspension was prepared. Splenocytes then underwent flow cytometry to analyze the immune cell population. RAW264.7 macrophages were treated with lipopolysaccharide (LPS) with or without the presence of TubA (10 μM) at 37 °C for 3 h to assess the effect on macrophage phagocytosis. We found that acute lung injury secondary to lethal sepsis was attenuated by TubA. Treatment with TubA restored the percentage of B lymphocytes, and significantly increased percentages of innate immune cells and macrophages compared to the vehicle-treated CLP group. Moreover, TubA significantly decreased the bacterial load in the spleen, and improved the phagocytic ability of RAW264.7 murine macrophages in vitro. Such findings may help to explain the beneficial effects of TubA treatment in a model of lethal sepsis, as previously reported.

Qiufang Deng

Department of Surgery

University of Michigan

Complete and Partial Aortic Occlusion for the Treatment of Hemorrhagic Shock in Swine

Qiufang Deng

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Surgery

University of Michigan

Complete and Partial Aortic Occlusion for the Treatment of Hemorrhagic Shock in Swine

Department of Surgery