A time course study of the protective effect of mesenteric lymph duct ligation on hemorrhagic shock-induced pulmonary injury and the toxic effects of lymph from shocked rats on endothelial cell monolayer permeability

Articles on hemorrhagic shock published between 2000 and 2021: A CiteSpace-Based bibliometric analysis

Objective

To conduct a bibliometric analysis of literature on hemorrhagic shock published between 2000 and 2021 with the help of Citespace to explore the current status, hotspots and research trends in this regard, with the results presented in a visualized manner.

Methods

The data over the past 22 years were retrieved from the Web of Science (WOS) Core Collection database and downloaded as the "Full Record and Cited References". Cooperative analysis, cluster analysis, co-citation analysis, and burst analysis were performed based on the data on countries/regions, institutions, journals, authors, and keywords through Citespace.

Results

A total of 2027 articles were retrieved. The number of annual publications fluctuated but was generally on an upward trend. The United States stands out as the most productive country (989 articles), the University of Pittsburgh the most productive publishing institution (109 articles), SHOCK the most cited journal (1486 articles), TAO LI the most productive author (40 articles), DEITCH EA the most cited author (261 times of citation), hemorrhagic shock the most frequent keyword (725 times of occurrence), and "traumatic brain injury" the most covered article in keyword clustering (29 articles). The burst analysis revealed Harvard University as the institution with the highest strength value and the Journal of Trauma and Acute Care Surgery the most important journal. It was also concluded that HASAN B ALAM, AARON M WILLIAMS, and LIMIN ZHANG may continue to publish high-quality articles in the future. In the meanwhile, both "protect" and "transfusion" were considered the hotspots and trends in current research.

Conclusions

The United States has been a major contributor to the publication of the articles over the past 22 years, with the most productive publishing institution, the most cited journal, and the most cited author all coming from the US. Hemorrhagic shock, injury, resuscitation, trauma, models, activation, expression, fluid resuscitation, rats, and nitric oxide are hot topics in relevant research. According to the keyword burst analysis, the areas related to "protect" and "transfusion" may rise as the research directions in the future. However, since the hotspots in the research of hemorrhagic shock are short-lived and fast-changing, the researchers should pay more attention to the development trend in this field.

Profiles of lipid, protein and microRNA expression in exosomes derived from intestinal epithelial cells after ischemia-reperfusion injury in a cellular hypoxia model

Intestinal ischemia-reperfusion injury leads to proinflammatory responses via gut-derived mediators, and accumulating evidence suggests that exosomes secreted by intestinal epithelial cells are involved in the development of systemic inflammation. Studies have reported changes in protein, lipid, and microRNA (miRNA) expression; however, considering the different experimental conditions, information on the relationships among these biomolecules remains insufficient. The aim of this study was to elucidate the multiple changes that simultaneously occur in exosomes after ischemic stimulation. Here, differentiated human intestinal Caco-2 cells were exposed to 95% air (normoxia group) or 5% O2 (hypoxia group) for 6 h. Cells in each group were subsequently incubated for 24 h in an atmosphere of 5% CO2 plus 95% air. The conditioned medium of each group was collected for isolating intestinal epithelial cell-derived exosomes. Together with proteome analyses, lipid analyses, and miRNA quantification, biological functional assays were performed using monocytic NF-κB reporter cells. Lipid metabolism-related protein expression was upregulated, miRNA levels were slightly altered, and unsaturated fatty acid-containing lysophosphatidylcholine concentration increased after hypoxia and reoxygenation injury; this suggested that the changes in exosomal components associated with ischemia-reperfusion injury activates inflammation, including the NF-κB pathway. This study elucidated the multiple changes that co-occur in exosomes after ischemic stimulation and partially clarified the mechanism underlying exosome-mediated inflammation after intestinal ischemic recanalization.

Recombinant Human Thrombomodulin Reduces Mortality and Acute Lung Injury Caused by Septic Peritonitis in Rats

This study aimed to investigate the therapeutic effects of recombinant human thrombomodulin (rhTM) on acute lung injury (ALI) caused by sepsis in rats. Rats that underwent cecal ligation and puncture (CLP) were treated with or without rhTM, and then mortality was analyzed. In another set of experiments, ALI was assessed. Furthermore, microthrombosis in the lungs was investigated by immunohistochemistry. Moreover, plasma inflammatory and anti-inflammatory cytokines, such as TNF-α, high-mobility group box chromosomal protein 1 (HMGB-1), and IL-10, were evaluated by ELISA. Production of TNF-α and HMGB-1 by isolated tissue macrophages (Mφs) was assessed in vitro. Mortality after CLP was significantly improved by rhTM treatment. In addition, rhTM treatment improved the wet/dry weight ratio of the lungs, the pulmonary microvascular permeability, and the lung injury scores in animals that underwent CLP. Microthrombosis was detected in the lungs after CLP. These pathophysiological changes were blunted by rhTM treatment. Increased plasma TNF-α and HMGB-1 levels were blunted by rhTM treatment; however, the anti-inflammatory cytokine IL-10 was significantly greater in the rhTM(+) group than in the rhTM(-) group. Increased TNF-α and HMGB-1 production by the tissue Mφs stimulated with LPS were significantly blunted by rhTM treatment in vitro, but the production of IL-10 by the tissue Mφs was not changed in the cells incubated with rhTM. Overall, rhTM improved the mortality caused by septic peritonitis. The possible mechanisms are most likely anti-inflammatory and anticoagulant effects, which lead to the prevention of ALI.

In Vitro Methods for Measuring the Permeability of Cell Monolayers

Cell monolayers, including endothelial and epithelial cells, play crucial roles in regulating the transport of biomolecules to underlying tissues and structures via intercellular junctions. Moreover, the monolayers form a semipermeable barrier across which leukocyte transmigration is tightly regulated. The inflammatory cytokines can disrupt the epithelial and endothelial permeability, thus the reduced barrier integrity is a hallmark of epithelial and endothelial dysfunction related with numerous pathological conditions, including cancer-related inflammation. Therefore, the assessment of barrier function is critical in in vitro models of barrier-forming tissues. This review summarizes the commercially available in vitro systems used to measure the permeability of cellular monolayers. The presented techniques are separated in two large groups: macromolecular tracer flux assays, and electrical impedance measurement-based permeability assays. The presented techniques are briefly described and compared.

The emerging therapeutic potential of extracellular vesicles in trauma

Traumatic injury is a major cause of morbidity and mortality worldwide, despite significant advances in treatments. Most deaths occur either very early, through massive head trauma/CNS injury or exsanguination (despite advances in transfusion medicine), or later after injury often through multiple organ failure and secondary infection. Extracellular vesicles (EVs) are known to increase in the circulation after trauma and have been used to limited extent as diagnostic and prognostic markers. More intriguingly, EVs are now being investigated as both causes of pathologies post trauma, such as trauma-induced coagulopathy, and as potential treatments. In this review, we highlight what is currently known about the role and effects of EVs in various aspects of trauma, as well as exploring current literature from investigators who have begun to use EVs therapeutically to alter the physiology and pathology of traumatic insults. The potential effectiveness of using EVs therapeutically in trauma is supported by a large number of experimental studies, but there is still some way to go before we understand the complex effects of EVs in what is already a complex disease process.

Mesenteric Lymph Duct Ligation Alleviates Acute Lung Injury Caused by Severe Acute Pancreatitis Through Inhibition of High Mobility Group Box 1-Induced Inflammation in Rats

BACKGROUND

Acute lung injury (ALI) is the most common complication and one of the leading causes of mortality of severe acute pancreatitis (SAP). Nevertheless, no effective therapeutic schemes are presently available.

AIMS

To investigate the effect and potential mechanism of mesenteric lymph duct ligation (MLDL) on experimental SAP-induced ALI.

METHODS

Immediately following MLDL, rats were subjected to SAP by retrograde injection of 5% sodium taurocholate into the biliopancreatic duct. At 24 h after modeling, tissues were collected for morphological examination. The levels of TNF-α, IL-6, intercellular adhesion molecule-1 (ICAM1), diamine oxidase (DAO), and D-lactic acid (D-LA) in serum, and the myeloperoxidase (MPO) activity in lung tissues were determined. Moreover, the expressions of high mobility group box 1 (HMGB1), receptor of advanced glycation endproducts (RAGE), and NF-κB p65 at the mRNA and protein levels in lung tissues, and the expressions of HMGB1, RAGE, and TNF-α at the mRNA level in intestinal lymphoid tissues were evaluated.

RESULTS

MLDL significantly attenuated the histological injury of the pancreas and lung and reduced the production of TNF-α, IL-6, and ICAM1. Besides, MLDL repressed the activity of MPO in the lung. However, the levels of serum DAO and D-LA were decreased without obvious morphological improvement in intestinal injury. Moreover, MLDL apparently reduced the up-regulation of HMGB1, RAGE, and NF-κB p65 in lung tissues, as well as the expressions of HMGB1, RAGE, and TNF-α in intestinal lymphoid tissues.

CONCLUSIONS

Mesenteric lymph was a source of harmful factors leading to SAP-ALI. MLDL could alleviate SAP-ALI probably by inhibiting HMGB1-induced production of inflammation factors.

The Gut-Lung Axis in Systemic Inflammation. Role of Mesenteric Lymph as a Conduit

Emerging evidence shows that after injury or infection, the mesenteric lymph acts as a conduit for gut-derived toxic factors to enter the blood circulation, causing systemic inflammation and acute lung injury. Neither the cellular and molecular identity of lymph factors nor their mechanisms of action have been well understood and thus have become a timely topic of investigation. This review will first provide a summary of background knowledge on gut barrier and mesenteric lymphatics, followed by a discussion focusing on the current understanding of potential injurious factors in the lymph and their mechanistic contributions to lung injury. We also examine lymph factors with antiinflammatory properties as well as the bidirectional nature of the gut-lung axis in inflammation.

A Modern View of the Interstitial Space in Health and Disease

Increases in the volume of the interstitial space are readily recognized clinically as interstitial edema formation in the loose connective tissue of skin, mucosa, and lung. However, the contents and the hydrostatic pressure of this interstitial fluid can be very difficult to determine even in experimental settings. These difficulties have long obscured what we are beginning to appreciate is a dynamic milieu that is subject to both intrinsic and extrinsic regulation. This review examines current concepts regarding regulation of interstitial volume, pressure, and flow and utilizes that background to address three major topics of interest that impact IV fluid administration. The first of these started with the discovery that excess dietary salt can be stored non-osmotically in the interstitial space with minimal impact on vascular volume and pressures. This led to the hypothesis that, along with the kidney, the interstitial space plays an active role in the long-term regulation of blood pressure. Second, it now appears that hypovolemic shock leads to systemic inflammatory response syndrome principally through the entry of digestive enzymes into the intestinal interstitial space and the subsequent progression of enzymes and inflammatory agents through the mesenteric lymphatic system to the general circulation. Lastly, current evidence strongly supports the non-intuitive view that the primary factor leading to inflammatory edema formation is a decrease in interstitial hydrostatic pressure that dramatically increases microvascular filtration.

Mesenteric Lymph Duct Drainage Attenuates Lung Inflammatory Injury and Inhibits Endothelial Cell Apoptosis in Septic Rats

The present study was to investigate the effect of mesenteric lymph duct drainage on lung inflammatory response, histological alteration, and endothelial cell apoptosis in septic rats. Animals were randomly assigned into four groups: control, sham surgery, sepsis, and sepsis plus mesenteric lymph drainage. We used the colon ascendens stent peritonitis (CASP) procedure to induce the septic model in rats, and mesenteric lymph drainage was performed with a polyethylene (PE) catheter inserted into mesenteric lymphatic. The animals were sacrificed at the end of CASP in 6 h. The mRNA expression levels of inflammatory mediators were measured by qPCR, and the histologic damage were evaluated by the pathological score method. It was found that mesenteric lymph drainage significantly reduced the expression of TNF-α, IL-1β, and IL-6 mRNA in the lung. Pulmonary interstitial edema and infiltration of inflammatory cells were alleviated by mesenteric lymph drainage. Moreover, increased mRNA levels of TNF-α, IL-1β, IL-6 mRNA, and apoptotic rate were observed in PMVECs treated with septic lymph. These results indicate that mesenteric lymph duct drainage significantly attenuated lung inflammatory injury by decreasing the expression of pivotal inflammatory mediators and inhibiting endothelial apoptosis to preserve the pulmonary barrier function in septic rats.

Antioxidant micronutrient supplementation in critically ill adults: A systematic review with meta-analysis and trial sequential analysis

BACKGROUND

The role of antioxidant micronutrient (AxM) supplementation in the critically ill patients has been controversial, and recent trials have suggested a tendency to harm. Therefore, we performed a systematic review with meta-analysis and trial sequential analysis (TSA) of randomized controlled trials (RCT) to examine the effect of AxM supplementation on clinical outcomes among critically ill adults.

METHODS

PubMed, EMBASE, Cochrane, CINAHL, LILACS, DARE, SCOPUS, and Web of sciences databases were searched from inception to March 2019. RCTs that compared AxM supplements with placebo in adult critically ill patients and reporting mortality as an outcomes were included. Trial quality was assessed using updated cochrane risk of bias (RoB-II) tool. Primary outcome was all-cause mortality. Secondary outcomes were 28-day mortality, intensive care unit (ICU) and hospital length of stay (LOS), ventilator days and infection between the two groups. Outcomes were summarised using random-effects estimators. Quality of evidence (QOE) was rated using Grading of Recommendations, Assessment, Development and Evaluation. Prior to final analysis, we repeated the search through September 2019. R version 3.6.2 and STATA version 13 were used for all statistical analyses.

RESULTS

Pooled analysis of 34 trials with 4678 patients revealed that AxM supplementation was associated with possible reduction in all-cause mortality (relative risk [RR], 0.89 [95%CI 0.79 to 0.99], TSA adjusted CI 0.77 to 1.03; Low QOE). Fragility index and number needed to treat were 1 and 41, respectively. Eight studies with low RoB (RR, 1.08; 95%CI 0.95 to 1.23; TSA CI, 0.64 to 1.82; moderate QOE) did not show mortality reduction with AxM supplementation.

SECONDARY OUTCOMES

ICU LOS (weighted mean difference [WMD], -0.84; 95%CI -1.50 to -0.18; moderate QOE), hospitalization days (WMD, -2.83; 95%CI -3.91to -1.75; low QOE) and ventilator days (WMD, -1.87; 95%CI -3.60 to -0.14; very low QOE) showed a statistically significant benefit with AxM supplementation. In meta-regression analysis, neither the duration of AxM therapy nor the dosage of selenium, which was the most widely studied AxM, reported an association with mortality.

CONCLUSION

Although AxM supplementation was associated with possible reduction in all-cause mortality, results from the TSA and studies with low RoB showing null effect suggest that the evidence of benefit is questionable. Secondary outcomes attained statistically significant benefit with AxM supplements, but the certainity of evidence was low. To summarize, current evidence does not justify administration of AxM in critically ill patients.

REGISTRATION

PROSPERO, CRD42019125898.

Precious cargo: Modulation of the mesenteric lymph exosome payload after hemorrhagic shock

BACKGROUND

Trauma/hemorrhagic shock (T/HS) causes a release of proinflammatory mediators into the mesenteric lymph (ML) that may trigger a systemic inflammatory response and subsequent organ failure. Recently, we showed that exosomes in postshock ML are biologically active mediators of this inflammation. Because the specific inflammatory mediators in postshock ML exosomes have yet to be characterized, we hypothesized that T/HS would lead to a distinct ML proinflammatory exosome phenotype that could be identified by proteomic analysis. We further hypothesized that their regulation by the neuroenteric axis via the vagus nerve would modify this proinflammatory profile.

METHODS

Male rats underwent an established T/HS model including 60 minutes of HS followed by resuscitation. Mesenteric lymph was collected before HS (preshock) and after resuscitation (postshock). A subset of animals underwent cervical vagus nerve electrical stimulation (VNS) after the HS phase. Liquid chromatography with tandem mass spectroscopy (LC-MS/MS) followed by protein identification, label free quantification, and bioinformatic analysis was performed on exosomes from the pre-shock and post-shock phases in the T/HS and T/HS + vagus nerve electrical stimulation groups. Biological activity of exosomes was evaluated using a monocyte nuclear factor kappa B (NF-κB) activity assay.

RESULTS

ML exosomes express a distinct protein profile after T/HS with enrichment in pathways associated with cell signaling, cell death and survival, and the inflammatory response. Stimulation of the vagus nerve following injury attenuated the transition of ML exosomes to this T/HS-induced inflammatory phenotype with protein expression remaining similar to pre-shock. Monocyte NF-κB activity was increased after exposure to ML exosomes harvested after T/HS, while ML exosomes from preshock had no effect on monocyte NF-κB expression.

CONCLUSION

Postshock ML exosomes carry a distinct, proinflammatory protein cargo. Stimulating the vagus nerve prevents the T/HS-induced changes in ML exosome protein payload and suggests a novel mechanism by which the neuroenteric axis may limit the systemic inflammatory response after injury.

Gastrointestinal dysfunction in the critically ill: a systematic scoping review and research agenda proposed by the Section of Metabolism, Endocrinology and Nutrition of the European Society of Intensive Care Medicine

BACKGROUND

Gastrointestinal (GI) dysfunction is frequent in the critically ill but can be overlooked as a result of the lack of standardization of the diagnostic and therapeutic approaches. We aimed to develop a research agenda for GI dysfunction for future research. We systematically reviewed the current knowledge on a broad range of subtopics from a specific viewpoint of GI dysfunction, highlighting the remaining areas of uncertainty and suggesting future studies.

METHODS

This systematic scoping review and research agenda was conducted following successive steps: (1) identify clinically important subtopics within the field of GI function which warrant further research; (2) systematically review the literature for each subtopic using PubMed, CENTRAL and Cochrane Database of Systematic Reviews; (3) summarize evidence for each subtopic; (4) identify areas of uncertainty; (5) formulate and refine study proposals that address these subtopics; and (6) prioritize study proposals via sequential voting rounds.

RESULTS

Five major themes were identified: (1) monitoring, (2) associations between GI function and outcome, (3) GI function and nutrition, (4) management of GI dysfunction and (5) pathophysiological mechanisms. Searches on 17 subtopics were performed and evidence summarized. Several areas of uncertainty were identified, six of them needing consensus process. Study proposals ranked among the first ten included: prevention and management of diarrhoea; management of upper and lower feeding intolerance, including indications for post-pyloric feeding and opioid antagonists; acute gastrointestinal injury grading as a bedside tool; the role of intra-abdominal hypertension in the development and monitoring of GI dysfunction and in the development of non-occlusive mesenteric ischaemia; and the effect of proton pump inhibitors on the microbiome in critical illness.

CONCLUSIONS

Current evidence on GI dysfunction is scarce, partially due to the lack of precise definitions. The use of core sets of monitoring and outcomes are required to improve the consistency of future studies. We propose several areas for consensus process and outline future study projects.

Lymphatic Pump Treatment Mobilizes Bioactive Lymph That Suppresses Macrophage Activity In Vitro

Context

By promoting the recirculation of tissue fluid, the lymphatic system preserves tissue health, aids in the absorption of gastrointestinal lipids, and supports immune surveillance. Failure of the lymphatic system has been implicated in the pathogenesis of several infectious and inflammatory diseases. Thus, interventions that enhance lymphatic circulation, such as osteopathic lymphatic pump treatment (LPT), should aid in the management of these diseases.

Objective

To determine whether thoracic duct lymph (TDL) mobilized during LPT would alter the function of macrophages in vitro.

Methods

The thoracic ducts of 6 mongrel dogs were cannulated, and TDL samples were collected before (baseline), during, and 10 minutes after LPT. Thoracic duct lymph flow was measured, and TDL samples were analyzed for protein concentration. To measure the effect of TDL on macrophage activity, RAW 264.7 macrophages were cultured for 1 hour to acclimate. After 1 hour, cell-free TDL collected at baseline, during LPT, and after TDL was added at 5% total volume per well and co-cultured with or without 500 ng per well of lipopolysaccharide (LPS) for 24 hours. As a control for the addition of 5% TDL, macrophages were cultured with phosphate-buffered saline (PBS) at 5% total volume per well and co-cultured with or without 500 ng per well of LPS for 24 hours. After culture, cell-free supernatants were assayed for nitrite (NO2-), tumor necrosis factor α (TNF-α) and interleukin 10 (IL-10). Macrophage viability was measured using flow cytometry.

Results

Lymphatic pump treatment significantly increased TDL flow and the flux of protein in TDL (P<.001). After culture, macrophage viability was approximately 90%. During activation with LPS, baseline TDL, TDL during LPT, and TDL after LPT significantly decreased the production of NO2-, TNF-α, and IL-10 by macrophages (P<.05). However, no significant differences were found in viability or the production of NO2-, TNF-α, or IL-10 between macrophages cultured with LPS plus TDL taken before, during, and after LPT (P>.05).

Conclusion

The redistribution of protective lymph during LPT may provide scientific rationale for the clinical use of LPT to reduce inflammation and manage edema.

ASK1-p38 cascaded signal mediates pulmonary microvascular endothelial barrier injury induced by the return of PHSML in rats

The return of post-hemorrhagic shock mesenteric lymph (PHSML) induces pulmonary vascular endothelial barrier dysfunction, which results in acute lung injury. Activation of the apoptosis signal-regulated kinase 1 (ASK1) and p38 mitogen-activated protein kinase (p38 MAPK) pathway has been shown to trigger inflammatory responses. However, whether the ASK1-p38 MAPK pathway is involved in the PHSML-induced pulmonary endothelial barrier dysfunction remains unclear. In the present study, permeability changes of pulmonary capillaries were found in vivo, and activation of the ASK1-p38 MAPK pathway was determined in vitro. PMVEC barrier dysfunction was determined by measuring TEER. Furthermore, junctional and cytoskeletal protein expressions were analyzed. The results showed that hemorrhagic shock led to a marked increase in the permeability of pulmonary capillaries in vivo, which was markedly alleviated by PHSML drainage. In cultured pulmonary microvascular endothelial cells (PMVECs), PHSML reduced the endothelial barrier function accompanied by upregulated p-ASK1 and p-p38 MAPK protein expression, impaired the cytoskeletal protein structure, and down-regulated junction protein expression. These adverse effects were eliminated by applying either Trx1 (ASK1 inhibitor) or SB203580 (p38 MAPK inhibitor). These results indicated that the ASK1-p38 MAPK pathway mediates PHSML-induced pulmonary vascular endothelial barrier dysfunction during hemorrhagic shock.

The return of post-hemorrhagic shock mesenteric lymph (PHSML) induces pulmonary vascular endothelial barrier dysfunction, which results in acute lung injury.

Lymphatic Vessel Network Structure and Physiology

The lymphatic system is comprised of a network of vessels interrelated with lymphoid tissue, which has the holistic function to maintain the local physiologic environment for every cell in all tissues of the body. The lymphatic system maintains extracellular fluid homeostasis favorable for optimal tissue function, removing substances that arise due to metabolism or cell death, and optimizing immunity against bacteria, viruses, parasites, and other antigens. This article provides a comprehensive review of important findings over the past century along with recent advances in the understanding of the anatomy and physiology of lymphatic vessels, including tissue/organ specificity, development, mechanisms of lymph formation and transport, lymphangiogenesis, and the roles of lymphatics in disease. © 2019 American Physiological Society. Compr Physiol 9:207-299, 2019.

Intravenous injection of post-hemorrhagic shock mesenteric lymph induces multiple organ injury in rats

Post-hemorrhagic shock mesenteric lymph (PHSML) has an important role in the multiple organ injuries caused by severe shock. The current study investigated whether intravenous injection of PHSML induces organ injury in normal rats. Following the establishment of hemorrhagic shock in donor rats (40±2 mmHg, 3 h), PHSML was drained during hypotension at 1-3 h and then injected to normal rats through the femoral vein within 30 min. The mean arterial pressure (MAP) was measured, and samples were obtained for analysis of histology and biochemical indices at 2.5 h post-PHSML administration. PHSML administration resulted in a significant decrease in MAP at the early and late stage of the experiment. Structural damage of the lung, kidney, heart and liver was also observed, and the levels of urea, creatinine, aspartate aminotransferase, total bile acid and creatine kinase MB isoenzyme were increased in the plasma. Additionally, PHSML injection significantly increased the levels of trypsin, tumor necrosis factor-α (TNF-α), intercellular adhesion molecule-1 and receptor of advanced glycation end-products in the plasma, malondialdehyde in the lung and myocardium, and TNF-α in the lung, kidney, myocardium and liver. Intravenous injection of PHSML induced multiple organ injury in normal rats via increases in trypsin activity, inflammatory factors and free radical production. The findings indicate that PHSML return is an important contributor to organ damage following hemorrhagic shock.

Exosomes in postshock mesenteric lymph are key mediators of acute lung injury triggering the macrophage activation via Toll-like receptor 4

Acute lung injury (ALI) is a common cause of morbidity in patients after severe injury due to dysregulated inflammation, which is believed to be driven by gut-derived inflammatory mediators carried via mesenteric lymph (ML). We have previously demonstrated that nano-sized extracellular vesicles, called exosomes, secreted into ML after trauma/hemorrhagic shock (T/HS) have the potential to activate immune cells in vitro Here, we assess the function of ML exosomes in the development of T/HS-induced ALI and the role of TLR4 in the ML exosome-mediated inflammatory response. ML exosomes isolated from rats subjected to T/HS stimulated NF-κB activation and caused proinflammatory cytokine production in alveolar macrophages. In vivo experiments revealed that intravenous injection of exosomes harvested after T/HS, but not before shock, caused recruitment of inflammatory cells in the lung, increased vascular permeability, and induced histologic ALI in naive mice. The exosome-depleted supernatant of ML had no effect on in vitro and in vivo inflammatory responses. We also demonstrated that both pharmacologic inhibition and genetic knockout of TLR4 completely abolished ML exosome-induced cytokine production in macrophages. Thus, our findings define the critical role of exosomes secreted into ML as a critical mediator of T/HS-induced ALI through macrophage TLR4 activation.-Kojima, M., Gimenes-Junior, J. A., Chan, T. W., Eliceiri, B. P., Baird, A., Costantini, T. W., Coimbra, R. Exosomes in postshock mesenteric lymph are key mediators of acute lung injury triggering the macrophage activation via Toll-like receptor 4.

Exosomes, not protein or lipids, in mesenteric lymph activate inflammation: Unlocking the mystery of post-shock multiple organ failure

BACKGROUND

Previous studies have shown that mesenteric lymph (ML) has a crucial role in driving the systemic inflammatory response after trauma/hemorrhagic shock (T/HS). The specific mediators in the ML that contribute to its biological activity remain unclear despite decades of study. Exosomes are extracellular vesicles that are shed into body fluids such as serum and urine that can mediate intercellular communication. We hypothesized that exosomes are present in the ML after trauma/shock and are responsible for the biological activity of ML.

METHODS

Male rats underwent cannulation of the vessels and mesenteric lymph duct. T/HS was induced by laparotomy and 60 minutes of HS (mean arterial pressure, 35 mmHg), followed by resuscitation. The ML was collected during three distinct time periods (pre-shock, shock, and resuscitation phase) and subsequently separated into exosome and supernatant fractions. Exosomes were characterized by electron microscope, nanoparticle tracking analysis, and immunoblotting. The biological activity of exosomes and supernatant of ML were characterized using a monocyte NF-κB reporter assay and by measuring macrophage intracellular TNF-α production.

RESULTS

Exosomes were identified in ML by size and expression of the exosome markers CD63 and HSP70. The number of exosomes present in the ML was 2-fold increased during shock and 4-fold decreased in resuscitation phase compared to pre-shock. However, biological activity of exosomes isolated during the resuscitation phase was markedly increased and caused an 8-fold increase in monocyte NF-κB activation compared to supernatant. Macrophage TNF-α production was also increased after exposure to exosomes harvested in the resuscitation phase. The ML supernatant fraction had no effect on TNF-α production during any phase.

CONCLUSIONS

Our findings show that exosomes, and not the liquid fraction of ML, are the major component triggering inflammatory responses in monocytes and macrophages after experimental T/HS.

Modulating the Biologic Activity of Mesenteric Lymph after Traumatic Shock Decreases Systemic Inflammation and End Organ Injury

Introduction

Trauma/hemorrhagic shock (T/HS) causes the release of pro-inflammatory mediators into the mesenteric lymph (ML), triggering a systemic inflammatory response and acute lung injury (ALI). Direct and pharmacologic vagal nerve stimulation prevents gut barrier failure and alters the biologic activity of ML after injury. We hypothesize that treatment with a pharmacologic vagal agonist after T/HS would attenuate the biologic activity of ML and prevent ALI.

Methods

ML was collected from male Sprague-Dawley rats after T/HS, trauma-sham shock (T/SS) or T/HS with administration of the pharmacologic vagal agonist CPSI-121. ML samples from each experimental group were injected into naïve mice to assess biologic activity. Blood samples were analyzed for changes in STAT3 phosphorylation (pSTAT3). Lung injury was characterized by histology, permeability and immune cell recruitment.

Results

T/HS lymph injected in naïve mice caused a systemic inflammatory response characterized by hypotension and increased circulating monocyte pSTAT3 activity. Injection of T/HS lymph also resulted in ALI, confirmed by histology, lung permeability and increased recruitment of pulmonary macrophages and neutrophils to lung parenchyma. CPSI-121 attenuated T/HS lymph-induced systemic inflammatory response and ALI with stable hemodynamics and similar monocyte pSTAT3 levels, lung histology, lung permeability and lung immune cell recruitment compared to animals injected with lymph from T/SS.

Conclusion

Treatment with CPSI-121 after T/HS attenuated the biologic activity of the ML and decreased ALI. Given the superior clinical feasibility of utilizing a pharmacologic approach to vagal nerve stimulation, CPSI-121 is a potential treatment strategy to limit end organ dysfunction after injury.

The digestive tract as the origin of systemic inflammation

Failure of gut homeostasis is an important factor in the pathogenesis and progression of systemic inflammation, which can culminate in multiple organ failure and fatality. Pathogenic events in critically ill patients include mesenteric hypoperfusion, dysregulation of gut motility, and failure of the gut barrier with resultant translocation of luminal substrates. This is followed by the exacerbation of local and systemic immune responses. All these events can contribute to pathogenic crosstalk between the gut, circulating cells, and other organs like the liver, pancreas, and lungs. Here we review recent insights into the identity of the cellular and biochemical players from the gut that have key roles in the pathogenic turn of events in these organ systems that derange the systemic inflammatory homeostasis. In particular, we discuss the dangers from within the gastrointestinal tract, including metabolic products from the liver (bile acids), digestive enzymes produced by the pancreas, and inflammatory components of the mesenteric lymph.

Dynamic changes in rat mesenteric lymph proteins following trauma using label-free mass spectrometry

Early events triggered by posttrauma/hemorrhagic shock currently represent a leading cause of morbidity and mortality in these patients. The causative agents of these events have been associated with increased neutrophil priming secondary to shock-dependent alterations of mesenteric lymph. Previous studies have suggested that unknown soluble components of the postshock mesenteric lymph are main drivers of these events. In the present study, we applied a label-free proteomics approach to further delve into the early proteome changes of the mesenteric lymph in response to hemorrhagic shock. Time-course analyses were performed by sampling the lymph every 30 min after shock up until 3 h (the time window within which a climax in neutrophil priming was observed). There are novel, transient early post-hemorrhagic shock alterations to the proteome and previously undocumented postshock protein alterations. These results underlie the triggering of coagulation and proinflammatory responses secondary to trauma/hemorrhagic shock, metabolic deregulation and apoptosis, and alterations to proteases/antiproteases homeostasis, which are suggestive of the potential implication of extracellular matrix proteases in priming neutrophil activation. Finally, there is a likely correlation between early postshock mesenteric lymph-mediated neutrophil priming and proteomics changes, above all protease/antiproteases impaired homeostasis (especially of serine proteases and metalloproteases).

A sphingosine-1 phosphate agonist (FTY720) limits trauma/hemorrhagic shock-induced multiple organ dysfunction syndrome

BACKGROUND

Trauma/hemorrhagic shock (T/HS) is one of the major consequences of battlefield injury as well as civilian trauma. FTY720 (sphingosine-1-phosphate agonist) has the capability to decrease the activity of the innate and adaptive immune systems and, at the same time, maintain endothelial cell barrier function and vascular homeostasis during stress. For this reason, we hypothesize that FTY720, as part of resuscitation therapy, would limit T/HS-induced multiple organ dysfunction syndrome in a rodent T/HS model.

METHODS

Rats subjected to trauma/sham shock (T/SS) or T/HS (30 mm Hg × 90 min) were administered FTY720 (1 mg/kg) post-T/HS during volume resuscitation. Lung injury (permeability to Evans blue dye), polymorphonuclear leukocyte (PMN) priming (respiratory burst activity), and red blood cell (RBC) rigidity were measured. In addition, lymph duct-cannulated rats were used to quantify the effect of FTY720 on gut injury (permeability and morphology) and the biologic activity of T/HS versus T/SS lymph on PMN-RBC and RBC deformability.

RESULTS

Trauma/hemorrhagic shock-induced increased lung permeability, PMN priming, and RBC rigidity were all abrogated by FTY720. The systemic protective effect of FTY720 was only partially at the gut level, because FTY720 did not prevent T/HS-induced gut injury (morphology or permeability); however, it did abrogate T/HS lymph-induced increased respiratory burst and RBC rigidity.

CONCLUSIONS

FTY720 limited T/HS-induced multiple organ dysfunction syndrome (lung injury, red cell injury, and neutrophil priming) as well as T/HS lymph bioactivity, although it did not limit gut injury.

Mesenteric lymph diversion abrogates 5-lipoxygenase activation in the kidney following trauma and hemorrhagic shock

BACKGROUND

Early acute kidney injury (AKI) following trauma is associated with multiorgan failure and mortality. Leukotrienes have been implicated both in AKI and in acute lung injury. Activated 5-lipoxygenase (5-LO) colocalizes with 5-LO-activating protein (FLAP) in the first step of leukotriene production following trauma and hemorrhagic shock (T/HS). Diversion of postshock mesenteric lymph, which is rich in the 5-LO substrate of arachidonate, attenuates lung injury and decreases 5-LO/FLAP associations in the lung after T/HS. We hypothesized that mesenteric lymph diversion (MLD) will also attenuate postshock 5-LO-mediated AKI.

METHODS

Rats underwent T/HS (laparotomy, hemorrhagic shock to a mean arterial pressure of 30 mm Hg for 45 minutes, and resuscitation), and MLD was accomplished via cannulation of the mesenteric duct. Extent of kidney injury was determined via histology score and verified by urinary neutrophil gelatinase-associated lipocalin assay. Kidney sections were immunostained for 5-LO and FLAP, and colocalization was determined by fluorescence resonance energy transfer signal intensity. The end leukotriene products of 5-LO were determined in urine.

RESULTS

AKI was evident in the T/HS group by derangement in kidney tubule architecture and confirmed by neutrophil gelatinase-associated lipocalin assay, whereas MLD during T/HS preserved renal tubule morphology at a sham level. MLD during T/HS decreased the associations between 5-LO and FLAP demonstrated by fluorescence resonance energy transfer microscopy and decreased leukotriene production in urine.

CONCLUSION

5-LO and FLAP colocalize in the interstitium of the renal medulla following T/HS. MLD attenuates this phenomenon, which coincides with pathologic changes seen in tubules during kidney injury and biochemical evidence of AKI. These data suggest that gut-derived leukotriene substrate predisposes the kidney and the lung to subsequent injury.

Intravenous infusion of mesenteric lymph from severe intraperitoneal infection rats causes lung injury in healthy rats

AIM: To investigate whether mesenteric lymph from rats with severe intraperitoneal infection (SII) induces lung injury in healthy rats.

METHODS: Twenty adult male specific pathogen-free Wistar rats were divided into two groups. Animals in the SII group received intraperitoneal injection of Escherichia coli (E. coli) at a dose of 0.3 mL/100 g. Control rats underwent the same procedure, but were injected with normal saline rather than E. coli. We ligated and drained the mesenteric lymphatic vessels and collected the mesenteric lymph. Mesenteric lymph collected from SII or control rats was infused intravenously into male healthy rats at a rate of 1 mL/h for 4 h. At the end of the infusion, all rats were sacrificed. Lungs were removed and examined histologically, and wet-to-dry weight (W/D) ratio and myeloperoxidase (MPO) activity were determined. Enzyme-linked immunosorbent assay (ELISA) was performed to determine the levels of the proinflammatory cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6. We performed Western blot to investigate the activation of Toll-like receptor (TLR)-4, and nuclear factor (NF)-κB p65.

RESULTS: Compared with the control infusion group, there were obvious pathological changes in the SII group. The W/D ratio was significantly increased in the SII compared to control infusion group (5.86 ± 0.06 vs 5.37 ± 0.06, P < 0.01). MPO activity significantly increased in the SII infusion rats with a mean level of 0.86 ± 0.02 U/g compared to 0.18 ± 0.05 U/g in the control group (P < 0.01). The concentrations of TNF-α and IL-6 were significantly increased in the SII infusion group. The concentration of TNF-α was significantly increased in the SII infusion rats compared to control infusion rats (2104.46 ± 245.91 vs 1475.13 ± 137.82 pg/mL, P < 0.01). The concentration of IL-6 was significantly increased in the SII infusion rats with a mean level of 50.56 ± 2.85 pg/mL compared to 43.29 ± 2.02 pg/mL (P < 0.01). The expression levels of TLR-4 (7496.68 ± 376.43 vs 4589.02 ± 233.16, P < 0.01) and NF-κB (8722.19 ± 323.96 vs 6498.91 ± 338.76, P < 0.01) were significantly increased in the SII infusion group compared to the control infusion group. The infusion of SII lymph, but not control lymph, caused lung injury.

CONCLUSION: The results indicate that SII lymph is sufficient to induce acute lung injury.

Group VIB Ca(2+)-independent phospholipase A(2γ) is associated with acute lung injury following trauma and hemorrhagic shock

BACKGROUND

Gut-derived mediators are carried via mesenteric lymph duct into systemic circulation after trauma/hemorrhagic shock (T/HS), thus leading to acute lung injury (ALI)/multiple-organ dysfunction syndrome. Phospholipase A2 (PLA(2)) is a key enzyme for the production of lipid mediators in posthemorrhagic shock mesenteric lymph (PHSML). However, the precise functions of PLA(2) subtype, such as cytosolic PLA(2), secretory PLA(2), and Ca-independent PLA(2), in the acute phase of inflammation have remained unclear. Our previous study has suggested that the activation of Group VIB Ca-independent PLA(2γ) (PLA(2γ)) may be associated with increased lyso-phosphatidylcholines (LPCs) in the PHSML. Therefore, our purpose was to verify the role of iPLA(2γ) on the production of 2-polyunsaturated LPC species and the pathogenesis of T/HS-induced ALI using an iPLA(2γ)-specific inhibitor, R-(E)-6-(bromoethylene)-3-(1-naphthalenyl)-2H-tetrahydropyran-2-one (R-BEL).

METHODS

Male Sprague-Dawley rats were anesthetized and cannulated in blood vessels and mesenteric lymph duct. Animals in the T/HS group underwent a midline laparotomy plus hemorrhagic shock (mean arterial pressure, 35 mm Hg, 30 minutes) and 2-hour resuscitation with shed blood and 2× normal saline. Trauma/sham shock rats were performed the identical procedure without hemorrhage. R-BEL or DMSO was administered 30 minutes before T/HS or trauma/sham shock. Polyunsaturated LPCs and arachidonic acid in the PHSML were analyzed with a liquid chromatography/electrospray ionization-mass spectrometry. Furthermore, ALI was assessed by lung vascular permeability, myeloperoxidase activity, and histology.

RESULTS

T/HS increased 2-polyunsaturated LPCs and arachidonic acid in the PHSML. The R-BEL pretreatment significantly decreased these lipids and also inhibited ALI.

CONCLUSION

The iPLA(2γ) enzyme is possibly involved in the pathogenesis of ALI following T/HS through the mesenteric lymph pathway.

Oral pretreatment with recombinant human lactoferrin limits trauma-hemorrhagic shock-induced gut injury and the biological activity of mesenteric lymph

BACKGROUND

Lactoferrin (LF) is a pleiotropic glycoprotein that is found in bodily secretions and is postulated to enhance the gastrointestinal barrier and promote mucosal immunity. Thus, the ability of talactoferrin, an oral recombinant form of human LF, to limit gut injury and the production of biologically active gut-derived products was tested using a rat model of trauma-hemorrhagic shock (T/HS).

METHODS

Male rats were orally dosed with vehicle or talactoferrin (1000 mg/kg, every day) for 5 d before being subjected to T/HS or trauma-sham shock (T/SS). Subsequently, rats were subjected to a laparotomy (trauma) and hemorrhagic shock (mean arterial pressure, 30-35 mm Hg × 90 min) or to T/SS, followed by resuscitation with their shed blood. Before inducing shock, the mesenteric lymphatic duct was catheterized for collection of mesenteric lymph. Four hours after the end of the shock or sham-shock period, rats were sacrificed, a segment of the distal ileum was collected for morphologic analysis, and lymph samples were processed and frozen. Subsequently, lymph samples were tested in several pharmacodynamic assays, including endothelial cell permeability, neutrophil respiratory burst activity, and red blood cell (RBC) deformability. Total white blood cell counts in lymph samples were also quantified.

RESULTS

Pretreatment with talactoferrin reduced the incidence of T/HS-induced morphologic injury of ileum to T/SS levels. Post-T/HS lymph from vehicle-treated rats increased endothelial monolayer permeability and neutrophil priming for an augmented respiratory burst, and induced loss of RBC deformability, compared with T/SS groups. Talactoferrin pretreatment significantly reduced the biological activity of T/HS lymph on respiratory burst activity and RBC deformability, but had no effect on the lymph cell count or endothelial cell permeability.

CONCLUSIONS

These results provide a proof of principle that prophylactic dosing of oral talactoferrin can potentially protect the gut in a T/HS model and limit the production of biologically active factors in rat gastrointestinal tissue subjected to ischemia-reperfusion-type injuries.

Regional susceptibility to stress-induced intestinal injury in the mouse

Injury to the intestinal mucosa is a life-threatening problem in a variety of clinical disorders, including hemorrhagic shock, trauma, burn, pancreatitis, and heat stroke. The susceptibility to injury of different regions of intestine in these disorders is not well understood. We compared histological injury across the small intestine in two in vivo mouse models of injury, hemorrhagic shock (30% loss of blood volume) and heat stroke (peak core temperature 42.4°C). In both injury models, areas near the duodenum showed significantly greater mucosal injury and reductions in villus height. To determine if these effects were dependent on circulating factors, experiments were performed on isolated intestinal segments to test for permeability to 4-kDa FITC-dextran. The segments were exposed to hyperthermia (42°C for 90 min), moderate simulated ischemia (Po2 ∼30 Torr, Pco2 ∼60 Torr, pH 7.1), severe ischemia (Po2 ∼20 Torr, Pco2 ∼80 Torr, pH 6.9), or severe hypoxia (Po2 ∼0 Torr, Pco2 ∼35 Torr) for 90 min, and each group was compared with sham controls. All treatments resulted in marked elevations in permeability within segments near the duodenum. In severe hypoxia or hyperthermia, permeability was also moderately elevated in the jejunum and ileum; in moderate or severe ischemia, permeability was unaffected in these regions. The results demonstrate increased susceptibility of proximal regions of the small intestine to acute stress-induced damage, irrespective of circulating factors. The predominant injury in the duodenum may impact the pattern of acute inflammatory responses arising from breach of the intestinal barrier, and such knowledge may be useful for designing therapeutic strategies.

Parasympathetic stimulation via the vagus nerve prevents systemic organ dysfunction by abrogating gut injury and lymph toxicity in trauma and hemorrhagic shock

We tested if vagus nerve stimulation (VNS) would prevent gut injury, mesenteric lymph toxicity, and systemic multiple organ dysfunction syndrome following trauma-hemorrhagic shock (T/HS). Four groups of experiments were performed. The first tested whether VNS (5 V for 10 min) would protect against T/HS-induced increases in gut and lung permeability as well as neutrophil priming. In the second experiment, mesenteric lymph was collected from rats subjected to T/HS or trauma-sham shock with or without VNS and then injected into naive mice to assess its biologic activity. Lung permeability, neutrophil priming, and red blood cell deformability were measured. Next, the role of the spleen in VNS-mediated protection was tested by measuring gut and lung injury in splenectomized rats subjected to sham or actual VNS. Lastly, the ability of nicotine to replicate the gut-protective effect of VNS was tested. Vagus nerve stimulation protected against T/HS-induced gut injury, lung injury, and neutrophil priming (P < 0.05). Not only did VNS limit organ injury after T/HS, but in contrast to the mesenteric lymph collected from the sham-VNS T/HS rats, the mesenteric lymph from the VNS T/HS rats did not cause lung injury, neutrophil priming, or loss of red blood cell deformability (P < 0.05) when injected into naive mice. Removal of the spleen did not prevent the protective effects of VNS on gut or lung injury after T/HS. Similar to VNS, the administration of nicotine also protected the gut from injury after T/HS. Vagus nerve stimulation prevents T/HS-induced gut injury, lung injury, neutrophil priming, and the production of biologically active mesenteric lymph. This protective effect of VNS was not dependent on the spleen but appeared to involve a cholinergic nicotinic receptor, because its beneficial effects could be replicated with nicotine.

Cellular basis of burn-induced cardiac dysfunction and prevention by mesenteric lymph duct ligation

BACKGROUND

Myocardial contractile depression develops 4 to 24 h after major burn injury. We have reported previously that in a rat burn injury model (≈40% of total body surface area burn), mesenteric lymph duct ligation (LDL) prior to burn prevented myocardial dysfunction. However, the underlying cellular and molecular mechanisms are not well understood.

MATERIALS AND METHODS

Left ventricular myocytes were isolated from sham burn (control), sham burn with LDL (sham + LDL), burn, and burn with LDL (burn + LDL) rats at 4 and 24 h after burn or sham burn. Electrophysiological techniques were used to study myocyte size, contractility and L-type Ca2+ channel current (ICa). Further studies examined changes in the messenger RNA expression levels of pore-forming subunit of the L-type Ca(2+) channel, α1C, and its auxiliary subunits, β1, β2, β3, and α2δ1, which modulate the abundance of the ICa in post-burn hearts.

RESULTS

Depressed myocyte contractility (≈20%) developed during 4 to 24 h post-burn compared with control, sham + LDL, or burn + LDL groups, a pattern of changes consistent with whole heart studies. There was no significant alteration in myocyte size. The ICa density was significantly decreased (≈30%) at 24 h post-burn, whereas the messenger RNA expression levels of Ca(2+) channel gene were not significantly altered at 4 and 24 h after burn injury.

CONCLUSIONS

These results suggest that the post-burn contractile phenotype in vivo was also present in isolated myocytes in vitro, but cellular remodeling was not a major factor. The results also suggest that changes in ICa regulation, but not from Ca(2+) channel gene modification, may be a key element involved in post-burn contractile depression and the beneficial effects of LDL.

Vagal nerve stimulation modulates gut injury and lung permeability in trauma-hemorrhagic shock

BACKGROUND

Hemorrhagic shock is known to disrupt the gut barrier leading to end-organ dysfunction. The vagus nerve can inhibit detrimental immune responses that contribute to organ damage in hemorrhagic shock. Therefore, we explored whether stimulation of the vagus nerve can protect the gut and recover lung permeability in trauma-hemorrhagic shock (THS).

METHODS

Male Sprague-Dawley rats were subjected to left cervical vagus nerve stimulation at 5 V for 10 minutes. The right internal jugular and femoral artery were cannulated for blood withdrawal and blood pressure monitoring, respectively. Animals were then subjected to hemorrhagic shock to a mean arterial pressure between 30 mm Hg and 35 mm Hg for 90 minutes then reperfused with their own whole blood. After observation for 3 hours, gut permeability was assessed with fluorescein dextran 4 in vivo injections in a ligated portion of distal ileum followed by Evans blue dye injection to assess lung permeability. Pulmonary myeloperoxidase levels were measured and compared.

RESULTS

Vagal nerve stimulation abrogated THS-induced lung injury (mean [SD], 8.46 [0.36] vs. 4.87 [0.78]; p < 0.05) and neutrophil sequestration (19.39 [1.01] vs. 12.83 [1.16]; p < 0.05). Likewise, THS gut permeability was reduced to sham levels.

CONCLUSION

Neuromodulation decreases injury in the THS model as evidenced by decreased gut permeability as well as decreased lung permeability and pulmonary neutrophil sequestration in a rat model.

Role of lipase-generated free fatty acids in converting mesenteric lymph from a noncytotoxic to a cytotoxic fluid

Recent studies have shown that mesenteric lymph plays a very important role in the development of multiple-organ dysfunction syndrome under critical conditions. Great efforts have been made to identify the biologically active molecules in the lymph. We used a trauma-hemorrhagic shock (T/HS) model and the superior mesenteric artery occlusion (SMAO) model, representing a global and a localized intestinal ischemia-reperfusion insult, respectively, to investigate the role of free fatty acids (FFAs) in the cytotoxicity of mesenteric lymph in rats. Lymph was collected before, during, and after (post) shock or SMAO. The post-T/HS and SMAO lymph, but not the sham lymph, manifested cytotoxicity for human umbilical vein endothelial cells (HUVECs). HUVEC cytotoxicity was associated with increased FFAs, especially the FFA-to-protein ratio. Addition of albumin, especially delipidated albumin, reduced this cytotoxicity. Lipase treatment of trauma-sham shock (T/SS) lymph converted it from a noncytotoxic to a cytotoxic fluid, and its toxicity correlated with the FFA-to-protein ratio in a fashion similar to that of the T/HS lymph, further suggesting that FFAs were the key components leading to HUVEC cytotoxicity. Analysis of lymph by gas chromatography revealed that the main FFAs in the post-T/HS or lipase-treated T/SS lymph were palmitic, stearic, oleic, and linoleic acids. When added to the cell culture at levels comparable to those in T/HS lymph, all these FFAs were cytotoxic, with linoleic acid being the most potent. In conclusion, this study suggests that lipase-generated FFAs are the key components resulting in the cytotoxicity of T/HS and SMAO mesenteric lymph.

Lipidomics analysis of mesenteric lymph after trauma and hemorrhagic shock

BACKGROUND

After trauma and hemorrhagic shock (T/HS), a variety of inflammatory mediators enter the systemic circulation through mesenteric lymph ducts, leading to acute lung injury and multiple-organ dysfunction syndrome. Recent studies have demonstrated that post-HS mesenteric lymph (PHSML) activates polymorphonuclear leukocytes (PMNs) and causes vascular endothelial cell and red blood cell dysfunction. Furthermore, PHSML contains proinflammatory mediators, such as biologically active lipids. The purpose of this study was to identify the lipid mediators in PHSML and plasma by liquid chromatography/electrospray ionization mass spectrometry and then estimate the biologic activities of the identified lipids on PMNs.

METHODS

PHSML was collected from male Sprague-Dawley rats undergoing trauma (laparotomy) plus HS (40 mm Hg, 30 minutes) or sham shock (SS). The lipids in PHSML and plasma were extracted using the methods of Bligh and Dyer, and liquid chromatography/electrospray ionization mass spectrometry was performed. The biologic activities (superoxide production and elastase release) of identified lipids on human PMNs were tested.

RESULTS

Phosphatidylcholine, lysophosphatidylcholine (LPC), phosphatidylethanolamine, lysophosphatidylethanolamine (LPE), and sphingomyelin were detected in the PHSML. Furthermore, linoleoyl, arachidonoyl, and docosahexaenoyl LPCs and LPEs significantly increased in the PHSML of the T/HS group as compared with those of the T/SS group. In the plasma, arachidonoyl and docosahexaenoyl LPCs of the T/HS group also significantly increased in comparison with that of the T/SS group. Linoleoyl and arachidonoyl LPCs and LPEs showed the priming activity on N-formyl-methionyl-leucyl-phenylalanine-activated PMNs. The elastase release was also induced by linoleoyl and arachidonoyl LPCs.

CONCLUSION

Mesenteric lymph after T/HS contains biologically active lipids, such as LPCs and LPEs with polyunsaturated fatty acids, which may be involved in the pathogenesis of acute lung injury/multiple-organ dysfunction syndrome.

Anticoagulants influence the in vitro activity and composition of shock lymph but not its in vivo activity

Many models of trauma-hemorrhagic shock (T/HS) involve the reinfusion of anticoagulated shed blood. Our recent observation that the anticoagulant heparin induces increased mesenteric lymph lipase activity and consequent in vitro endothelial cell cytotoxicity prompted us to investigate the effect of heparin-induced lipase activity on organ injury in vivo as well as the effects of other anticoagulants on mesenteric lymph bioactivity in vitro and in vivo. To investigate this issue, rats subjected to trauma-hemorrhage had their shed blood anticoagulated with heparin, the synthetic anticoagulant arixtra (fondaparinux sodium), or citrate. Arixtra, in contrast to heparin, did not increase lymph lipase activity or result in high levels of endothelial cytotoxicity. Yet, the arixtra-treated rats subjected to T/HS still manifested lung injury, neutrophil priming, and red blood cell dysfunction, which was totally abrogated by lymph duct ligation. Furthermore, the injection of T/HS mesenteric lymph, but not sham-shock lymph, collected from the arixtra rats into control mice recreated the pattern of lung injury, polymorphonucleocyte (PMN) priming, and red blood cell dysfunction observed after actual shock. Consistent with these observations, citrate-anticoagulated rats subjected to T/HS developed lung injury, and the injection of mesenteric lymph from the citrate-anticoagulated T/HS rats into control mice also resulted in lung injury. Based on these results, several conclusions can be drawn. First, heparin-induced increased mesenteric lymph lipase activity is not responsible for the in vivo effects of T/HS mesenteric lymph. Second, heparin should be avoided as an anticoagulant when studying the biology or composition of mesenteric lymph because of its ability to cause increases in lymph lipase activity that increase the in vitro cytotoxicity of these lymph samples.

Micronutrient supplementation for critically ill adults: a systematic review and meta-analysis

OBJECTIVE

This systematic review assessed the effects of micronutrient supplementation on adults recovering from critical illness. Primary outcomes included clinical endpoints (mortality, infectious complications, length of intensive care unit and of hospital stay). Secondary outcomes included descriptions of practice issues, micronutrient status, morbidity, course of the acute-phase response, and oxidative stress.

METHODS

Electronic bibliographic databases, bibliographies of retrieved articles, and personal files were searched and reviewed. Randomized controlled trials (RCTs) of micronutrient supplementation in adult critically ill patients administered enterally and/or parenterally in addition to their routine care were included. Two authors independently extracted data and assessed trial quality. The random-effects model was used to estimate overall relative risk (RR)/mean difference and effect size. P<0.05 was considered statistically significant.

RESULTS

Fifteen (n=1714) and 18 (n=1849) RCTs were included for the primary and secondary objectives, respectively. Fourteen trials (n=1468) showed a statistically significant decrease in overall mortality (RR 0.78, 95% confidence interval 0.67-0.90, I2=0%, P=0.0009). Six RCTs (n=1194) indicated a statistically significant decrease in 28-d mortality (RR 0.75, 95% confidence interval 0.63-0.88, I2=0%, P=0.0006). Micronutrient supplementation was not associated with a decrease in infectious complications, length of intensive care unit, or length of hospital stay. In subgroup analyses, a sensitivity analysis of combined micronutrients indicated a significant decrease in mortality (RR 0.69, 95% confidence interval 0.54-0.90, I2=2%, P=0.006). The secondary outcomes confirmed that timing, duration, and dosing appear to be key factors to ensure optimal clinical benefit.

CONCLUSION

This review does suggest a potential benefit of micronutrient supplementation in critically ill adults by possibly being associated with a decrease in mortality.

Proteomic analysis of human mesenteric lymph

Extensive animal work has established mesenteric lymph as the mechanistic link between gut ischemia/reperfusion and distant organ injury. Our trauma and transplant services provide a unique opportunity to assess the relevance of our animal data to human mesenteric lymph under conditions that simulate those used in the laboratory. Mesenteric lymph was collected from 11 patients with lymphatic injuries, during semielective spine reconstruction or immediately before organ donation. The lymph was tested for its ability to activate human neutrophils in vitro and was analyzed by label-free proteomic analysis. Human mesenteric lymph primed human polymorphonuclear neutrophils in a pattern similar to that observed in previous rodent, swine, and primate studies. A total of 477 proteins were identified from the 11 subjects' lymph samples with greater than 99% confidence. In addition to classic serum proteins, markers of hemolysis, extracellular matrix components, and general tissue damage were identified. Both tissue injury and shock correlate strongly with production of bioactive lymph. Products of red blood cell hemolysis correlate strongly with human lymph bioactivity, and immunoglobulins have a negative correlation with the proinflammatory lymph. These human data corroborate the current body of research implicating postshock mesenteric lymph in the development of systemic inflammation and multiple organ failure. Further studies will be required to determine if the proteins identified participate in the pathogenesis of multiple organ failure and if they can be used as diagnostic markers.

Intestinal lymph-borne factors induce lung release of inflammatory mediators and expression of adhesion molecules after an intestinal ischemic insult

BACKGROUND

Intestinal ischemia and reperfusion (I/R) is a documented cause of acute lung injury (ALI) and systemic inflammation. We previously reported that obstruction of thoracic lymphatic flow during intestinal I/R blunts pulmonary neutrophil recruitment and microvascular injury and decreases the systemic levels of tumor necrosis factor. Here, we consider the existence of a gut-lung axis promoting the induction of systemic inflammation, whereby drained intestinal lymph stimulates lung expression of adhesion molecules and matrix components and generation of inflammatory mediators.

MATERIAL AND METHODS

Upon administration of anesthesia, male Wistar rats were subjected to occlusion of the superior mesenteric artery for 45 min, followed by 2 h of intestinal reperfusion (I/R); groups of rats were subjected to I/R with or without thoracic lymphatic duct ligation immediately before the procedure. The non-manipulated rats were used to investigate basal parameters.

RESULTS

Obstruction of thoracic lymphatic flow before intestinal I/R decreased the ability of cultured lung tissue explants to release IL-1β, IL-10, and VEGF. In contrast, lymphatic obstruction normalized the elevated lung expression of PECAM-1 caused by intestinal I/R. On the other hand, lung E-selectin expression was significantly reduced, whereas fibronectin expression and collagen synthesis were not affected. Lymph levels of LTB(4) and TXB(2) were found to be significantly increased.

CONCLUSIONS

These data suggest that lymph factors drained from the intestine during ischemic trauma stimulate the lung to generate inflammatory mediators and alter the expression of adhesion molecules. Disturbances in lung homeostasis mediated by lymph might contribute to the spread of inflammatory processes, thereby accounting for the systemic inflammation induced by intestinal I/R.

Lymph duct ligation during ischemia/reperfusion prevents pulmonary dysfunction in a rat model with ω-3 polyunsaturated fatty acid and glutamine

OBJECTIVE

The release of injurious factors into the mesenteric lymph from the ischemic intestine has been shown to contribute to lung injury and systemic inflammation after severe injury. We studied the effects of lung injury and systemic inflammatory reaction after intestinal ischemia/reperfusion and mesenteric lymph duct ligation with different nutritional statuses.

METHODS

Rats (n = 72) were fed with a normal diet or received one of three diets (enteral nutrition, glutamine, or ω-3 polyunsaturated fatty acid) that were isocaloric and isonitrogenous. After 7 d, rats were subjected to 60 min of intestinal ischemia, ischemia plus mesenteric lymph duct ligation, or sham procedures. After 3 d of ischemia, the lymph nodes, lung, intestinal, liver, and blood were harvested and analyzed.

RESULTS

In the different groups, lung injury, including levels of myeloperoxidase, nitric oxide, nitric oxide synthase, and the index of alveolar apoptosis, were partly prevented by mesenteric lymph duct ligation (P < 0.05). Likewise, the rats with ischemia/reperfusion, but not those with duct ligation plus ischemia/reperfusion, had a significant increase in intestinal permeability and decreased mucosal thickness. The serum cytokine and endotoxin concentrations were also lower in the lymph duct ligation groups, although there was no significant difference between lymph duct ligation and sham procedure. The lung and intestinal injuries were attenuated in the groups fed with glutamine and ω-3 polyunsaturated fatty acid.

CONCLUSION

These results indicate that lymph duct ligation prevents lung injury, a systemic inflammation reaction, and gut-barrier dysfunction. Enteral glutamine and ω-3 polyunsaturated fatty acid modified the gut inflammation, prevented lung injury, and attenuated the systemic inflammation reaction.

Mesenteric lymph from rats with trauma-hemorrhagic shock causes abnormal cardiac myocyte function and induces myocardial contractile dysfunction

Myocardial contractile dysfunction develops following trauma-hemorrhagic shock (T/HS). We have previously shown that, in a rat fixed pressure model of T/HS (mean arterial pressure of 30-35 mmHg for 90 min), mesenteric lymph duct ligation before T/HS prevented T/HS-induced myocardial contractile depression. To determine whether T/HS lymph directly alters myocardial contractility, we examined the functional effects of physiologically relevant concentrations of mesenteric lymph collected from rats undergoing trauma-sham shock (T/SS) or T/HS on both isolated cardiac myocytes and Langendorff-perfused whole hearts. Acute application of T/HS lymph (0.1-2%), but not T/SS lymph, induced dual inotropic effects on myocytes with an immediate increase in the amplitude of cell shortening (1.4 ± 0.1-fold) followed by a complete block of contraction. Similarly, T/HS lymph caused dual, positive and negative effects on cellular Ca²⁺ transients. These effects were associated with changes in the electrophysiological properties of cardiac myocytes; T/HS lymph initially prolonged the action potential duration (action potential duration at 90% repolarization, 3.3 ± 0.4-fold), and this was followed by a decrease in the plateau potential and membrane depolarization. Furthermore, intravenous infusion of T/HS lymph, but not T/SS lymph, caused myocardial contractile dysfunction at 24 h after injection, which mimicked actual T/HS-induced changes; left ventricular developed pressure (LVDP) and the maximal rate of LVDP rise and fall (±dP/dt(max)) were decreased and inotropic response to Ca²⁺ was blunted. However, the contractile responsiveness to β-adrenergic receptor stimulation in the T/HS lymph-infused hearts remained unchanged. These results suggest that T/HS lymph directly causes negative inotropic effects on the myocardium and that T/HS lymph-induced changes in myocyte function are likely to contribute to the development of T/HS-induced myocardial dysfunction.

Leukotriene biosynthesis inhibition ameliorates acute lung injury following hemorrhagic shock in rats

Background

Hemorrhagic shock followed by resuscitation is conceived as an insult frequently induces a systemic inflammatory response syndrome and oxidative stress that results in multiple-organ dysfunction syndrome including acute lung injury. MK-886 is a leukotriene biosynthesis inhibitor exerts an anti inflammatory and antioxidant activity.

Objectives

The objective of present study was to assess the possible protective effect of MK-886 against hemorrhagic shock-induced acute lung injury via interfering with inflammatory and oxidative pathways.

Materials and methods

Eighteen adult Albino rats were assigned to three groups each containing six rats: group I, sham group, rats underwent all surgical instrumentation but neither hemorrhagic shock nor resuscitation was done; group II, Rats underwent hemorrhagic shock (HS) for 1 hr then resuscitated with Ringer's lactate (1 hr) (induced untreated group, HS); group III, HS + MK-886 (0.6 mg/kg i.p. injection 30 min before the induction of HS, and the same dose was repeated just before reperfusion period). At the end of experiment (2 hr after completion of resuscitation), blood samples were collected for measurement of serum tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). The trachea was then isolated and bronchoalveolar lavage fluid (BALF) was carried out for measurement of leukotriene B₄ (LTB₄), leukotriene C₄ (LTC₄) and total protein. The lungs were harvested, excised and the left lung was homogenized for measurement of malondialdehyde (MDA) and reduced glutathione (GSH) and the right lung was fixed in 10% formalin for histological examination.

Results

MK-886 treatment significantly reduced the total lung injury score compared with the HS group (P < 0.05). MK-886 also significantly decreased serum TNF-α & IL-6; lung MDA; BALF LTB₄, LTC₄ & total protein compared with the HS group (P < 0.05). MK-886 treatment significantly prevented the decrease in the lung GSH levels compared with the HS group (P < 0.05).

Conclusions

The results of the present study reveal that MK-886 may ameliorate lung injury in shocked rats via interfering with inflammatory and oxidative pathways implicating the role of leukotrienes in the pathogenesis of hemorrhagic shock-induced lung inflammation.

Heparin use in a rat hemorrhagic shock model induces biologic activity in mesenteric lymph separate from shock

Experimental data have shown that mesenteric lymph from rats subjected to trauma-hemorrhagic shock (THS) but not trauma-sham shock induces neutrophil activation, cytotoxicity, decreased red blood cell (RBC) deformability, and bone marrow colony growth suppression. These data have led to the hypothesis that gut factors produced from THS enter the systemic circulation via the mesenteric lymphatics and contribute to the progression of multiple organ failure after THS. Ongoing studies designed to identify bioactive lymph agents implicated factors associated with the heparin use in the THS procedure. We investigated if heparin itself was responsible for reported toxicity to human umbilical vein endothelial cells (HUVECs). Human umbilical vein endothelial cell toxicity was not induced by lymph when alternate anticoagulants (citrate and EDTA) were used in THS. Human umbilical vein endothelial cell toxicity was induced by lymph after heparin but not saline or citrate injection into trauma-sham shock and naive animals and was dose dependent. Activities of both heparin-releasable lipases (lipoprotein and hepatic) were detected in the plasma and lymph from THS and naive animals receiving heparin but not citrate or saline. Lymph-induced HUVEC toxicity correlated with lymph lipase activities. Finally, incubation of HUVECs with purified lipoprotein lipase added to naive lymph-induced toxicity in vitro. These data show that heparin, not THS, is responsible for the reported lymph-mediated HUVEC toxicity through its release of lipases into the lymph. These findings can provide alternative explanations for several of the THS effects reported in the literature using heparin models, thus necessitating a review of previous work in this field.

Intravenous injection of mesenteric lymph produced during hemorrhagic shock decreases RBC deformability in the rat

OBJECTIVE

To test the hypothesis that gut-derived factors carried in trauma-hemorrhagic shock (T/HS) lymph are sufficient to induce red blood cells (RBC) injury, to investigate their potential mechanisms of action, and to define the time post-T/HS that these factors appear in the lymph.

METHODS

Mesenteric lymph collected from T/HS or trauma-sham shock (T/SS) rats over different time periods was injected intravenously into male rats at a rate of 1 mL/h for 3 hours. RBC deformability was measured using laser-assisted ektacytometer to calculate the elongation index. From the shear-stress elongation curve, the stress required for the erythrocytes to reach 50% of their maximal elongation was also determined. RBC deformability was measured before lymph infusion and at 1 hour and 3 hours after the initiation of lymph infusion. The effect of the lymph samples (5% v/v) was also determined in vitro by incubating naïve whole blood with the lymph samples. The potential role of T/HS lymph-induced RBC oxidant injury mediated by inducible nitric oxide synthase (iNOS)-generated oxidants and/or white blood cells (WBC) was investigated using iNOS inhibitors and WBC depletion, respectively. In all the in vivo studies, five to seven rats were studied per group.

RESULTS

The intravenous injection of T/HS lymph but not T/SS lymph caused in vivo RBC injury. The biological activity of T/HS lymph varied over time with the RBC-injurious factors being produced only during the first 3 hours postshock. The in vivo inhibition of iNOS did not prevent lymph-induced RBC injury. T/HS lymph incubated in vitro with naïve whole blood resulted in RBC injury, but this injury was not observed in blood depleted of WBC.

CONCLUSIONS

These results indicate that T/HS lymph produced during the initial 3-hour postshock period is sufficient to induce RBC injury in otherwise normal rats and that the lymph-induced RBC injury is not dependent on activation of the iNOS pathway but seems to require WBC.

Loss of the intestinal mucus layer in the normal rat causes gut injury but not toxic mesenteric lymph nor lung injury

There is substantial evidence that gut barrier failure is associated with distant organ injury and systemic inflammation. After major trauma or stress, the factors and mechanisms involved in gut injury are unknown. Our primary hypothesis is that loss of the intestinal mucus layer will result in injury of the normal gut that is exacerbated by the presence of luminal pancreatic proteases. Our secondary hypothesis is that the injury produced in the gut will result in the production of biologically active mesenteric lymph and consequently distant organ (i.e., lung) injury. To test this hypothesis, five groups of rats were studied: 1) uninstrumented naive rats; 2) control rats in which a ligated segment of distal ileum was filled with saline; 3) rats with pancreatic proteases placed in their distal ileal segments; 4) rats with the mucolytic N-acetylcysteine (NAC) placed in their distal ileal segments; and 5) rats exposed to NAC and pancreatic proteases in their ileal segments. The potential systemic consequences of gut injury induced by NAC and proteases were assessed by measuring the biological activity of mesenteric lymph as well as gut-induced lung injury. Exposure of the normal intestine to NAC, but not saline or proteases, led to increased gut permeability, loss of mucus hydrophobicity, a decrease in the mucus layer, as well as morphological evidence of villous injury. Although proteases themselves did not cause gut injury, the combination of pancreatic proteases with NAC caused more severe injury than NAC alone, suggesting that once the mucus barrier is impaired, luminal proteases can injure the now vulnerable gut. Because comparable levels of gut injury caused by systemic insults are associated with gut-induced lung injury, which is mediated by biologically active factors in mesenteric lymph, we next tested whether this local model of gut injury would produce active mesenteric lymph or lead to lung injury. It did not, suggesting that gut injury by itself may not be sufficient to induce distant organ dysfunction. Therefore, loss of the intestinal mucus layer, especially in the presence of intraluminal pancreatic proteases, is sufficient to lead to injury and barrier dysfunction of the otherwise normal intestine but not to produce gut-induced distant organ dysfunction.

Proteomic analysis of post-hemorrhagic shock mesenteric lymph

Recent studies have documented the association of mesenteric lymphatic route with adult respiratory distress syndrome and multiple organ failure after hemorrhagic shock. However, the mediators and mechanisms of the toxic effects of mesenteric lymph remain unclear. This study aimed to identify mediators or biomarkers in the mesenteric lymph through comparative proteomic analysis. Fourteen mature male Sprague-Dawley rats were randomly divided and subjected to trauma (laparotomy) plus hemorrhagic shock or trauma plus sham shock. Mesenteric lymph samples were collected before shock and at 3 h after resuscitation from hemorrhagic shock (or sham shock). To investigate changes in proteome profiles between preshock and 3-h postshock (or 3-h post-sham shock) mesenteric lymph samples, two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry were performed. We found a more than 2-fold change in abundance of 31 protein spots in the lymph samples. Mass spectrometry analyses identified 12 distinct proteins. Four proteins were consistently upregulated in the 3-h postshock lymph samples, including serum albumin precursor, two isoforms of cytoplasmic actin, complement C3 precursor, and major urinary protein precursor. Two proteins, including haptoglobin and one unidentified protein, were consistently downregulated. The deregulation of these proteins was confirmed by Western blots. Most of these altered proteins are functionally implicated in tissue inflammation. The findings of this study provide a starting point for investigating the functions of these proteins in hemorrhagic shock-induced lung injury and hold great promise for the development of potential therapeutic interventions.

Claude H. Organ, Jr. memorial lecture: splanchnic hypoperfusion provokes acute lung injury via a 5-lipoxygenase-dependent mechanism

Postinjury multiple organ failure (MOF) is the net result of a dysfunctional immune response to injury characterized by a hyperactive innate system and a suppressed adaptive system. Acute lung injury (ALI) is the first clinical manifestation of organ failure, followed by renal and hepatic dysfunction. Circulatory shock is integral in the early pathogenesis of MOF, and the gut has been invoked as the motor of MOF. Mesenteric lymph is recognized as the mechanistic link between splanchnic ischemia/reperfusion and distant organ dysfunction, but the specific mediators remain to be defined. Current evidence suggests the lipid fraction of postshock mesenteric lymph is central in the etiology of ALI. Specifically, our recent work suggests that intestinal phospholipase A2 generated arachidonic acid and its subsequent 5-lipoxygenase products are essential in the pathogenesis of ALI. Proteins conveyed via postshock mesenteric lymph also may have an important role. Elucidating these mediators and the timing of their participation in pulmonary inflammation is critical in translating our current knowledge to new therapeutic strategies at the bedside.

Effect of biliary tract external drainage on cytokine expression and histomorphology of intestine, liver, and lung in rats with hemorrhagic shock

OBJECTIVE

To investigate the protective effect of biliary tract external drainage on cytokine expression and pathomorphism of intestine, liver, and lung in rats with hemorrhagic shock.

DESIGN

Randomized, control animal study.

SETTING

This study was conducted at The Institution Digestive Surgery Research Laboratory of Shanghai Jiao Tong University.

SUBJECTS

Sprague-Dawley rats.

INTERVENTIONS

Biliary tract external drainage was performed by inserting a cannula into the bile duct. Hemorrhagic shock was induced by drawing blood from the carotid artery.

MEASUREMENTS AND MAIN RESULTS

Twenty-four Sprague-Dawley rats were randomized to three equal groups of eight: sham shock; hemorrhagic shock; and hemorrhagic shock plus bile duct drainage. The messenger RNA expression of tumor necrosis factor-alpha, interleukin-6 in the intestine, liver, and lung tissue from the three groups were analyzed by reverse transcription-polymerase chain reaction. Tumor necrosis factor-alpha was analyzed in the bile of the rats by enzyme-linked immunosorbent assay. Histology of intestine, liver, and lung was performed in all groups by hematoxylin and eosin staining. The messenger RNA expression of tumor necrosis factor-alpha was significantly increased in the hemorrhagic shock group compared with the sham shock group (intestine 0.54 +/- 0.07 vs. 0.37 +/- 0.05, liver 1.01 +/- 0.06 vs. 0.56 +/- 0.07, lung 0.94 +/- 0.07 vs. 0.62 +/- 0.06). The messenger RNA expression of interleukin-6 was also significantly increased in the hemorrhagic shock group compared with the sham shock group (intestine 0.89 +/- 0.12 vs. 0.50 +/- 0.09, liver 1.07 +/- 0.10 vs. 0.57 +/- 0.12, lung 1.09 +/- 0.09 vs. 0.67 +/- 0.06). Biliary tract external drainage reduced significantly the messenger RNA expression of tumor necrosis factor-alpha (intestine 0.43 +/- 0.06 vs. 0.54 +/- 0.07, liver 0.74 +/- 0.18 vs. 1.01 +/- 0.06, lung 0.87 +/- 0.15 vs. 0.94 +/- 0.07) and interleukin-6 (intestine 0.60 +/- 0.11 vs. 0.89 +/- 0.12, liver 0.71 +/- 0.16 vs. 1.07 +/- 0.10, lung 0.88 +/- 0.25 vs. 1.09 +/- 0.09). The concentration of tumor necrosis factor-alpha in bile was significantly higher in the hemorrhagic shock group compared with the sham shock group (31.22 +/- 6.44 ng/mL vs. 15.49 +/- 3.64 ng/mL, p < .01). The histologic observation of the intestine, liver, and lung showed that the biliary tract external drainage significantly attenuate the putrescence and exfoliation of intestinal villi, denaturation and putrescence of hepatocytes, edema, and inflammatory cells infiltration of lung.

CONCLUSIONS

Biliary tract external drainage decreases the messenger RNA expression of tumor necrosis factor-alpha, interleukin-6 and attenuate the tissue injury of the intestine, liver, and lung in rats model of hemorrhagic shock. The gut-liver axis was implicated to play a crucial role in hemorrhagic shock-induced multiple organ dysfunction syndrome.