Mesenteric lymph is responsible for post-hemorrhagic shock systemic neutrophil priming

Sustained bile drainage decreases the organs injuries via inflammation-associated factors modulation in a severe acute pancreatitis rat model

The timely and effective treatment for severe acute pancreatitis (SAP) is favorable to prognosis. Decompression of the bile duct might be a feasible way to decrease the progression of SAP. The present study investigated the effects of sustained bile external drainage on organs injury caused by SAP in Sprague-Dawley (SD) rats and the mechanisms involved. A total of 72 female SD rats weighting 190-230 g were randomly divided into four groups (n=18): Sham operation group (SOG), SOG + bile drainage group (BDG), SAP group, and SAP + BDG. Sodium taurocholate solution (4%; 1 mg/kg body weight) was used to set up SAP model via injection of retrograde puncture of biliopancreatic duct through the duodenum. A cannula was inserted into the bile duct and fixed externally to establish BDG model. At each time points (t=3, 6, 12; n=6), tissues from the liver, lung, and pancreas, and blood samples were collected. Serum amylase (AMY) was analyzed in all the samples. The levels of tumor necrosis factor-α (TNF-α), heme oxygenase-1 (HO-1), interleukin-10 (IL-10) and high mobility group box 1 (HMGB1) were detected by ELISA. Hematoxylin-eosin staining was performed to observe the histopathological changes, and nuclear transcription factor (NF)-κB-p65 levels in the pancreas were analyzed by western blotting. The data indicated that BDG alleviated the SAP progression and multiple organs injuries. Meanwhile, the histopathological changes of the pancreas, liver, and lungs were improved by BDG. BDG decreased the pathological scores of pancreas significantly (P<0.05). The levels of AMY, TNF-α, HMGB1, and NF-κB-p65 were significantly downregulated by BDG (P<0.05), while the level of HO-1 was upregulated and IL-10 was unchanged. In summary, BDG may attenuate the multiple organs injuries caused by SAP via downregulation of TNF-α, HMGB1, NF-κB-p65 and upregulation of HO-1.

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.

Tranexamic acid decreases rodent hemorrhagic shock-induced inflammation with mixed end-organ effects

Beyond its anti-fibrinolytic mechanism, tranexamic acid has been suggested to have anti-inflammatory properties which may contribute to the survival benefit it provides to trauma patients. The objective of this study was to assess possible immunomodulatory effects of tranexamic acid as well as potential amelioration of end-organ injury in a rodent hemorrhagic shock model. Controlled hemorrhagic shock was induced in adult Sprague Dawley rats to a mean arterial pressure of 30 mmHg. Groups of 10 rats were administered intravenous tranexamic acid (300mg/kg) or vehicle control (normal saline) intravenously 15 minutes after the induction of shock. After 60 minutes of hemorrhagic shock, resuscitation was started. Animals were euthanized at six, 24, or 72 hours from the start of shock. Serum laboratory values to include inflammatory biomarkers were measured, and end organ histology was evaluated. Tranexamic acid treatment was associated with a significant decrease in serum IL-1β at six and 24 hours and IL-10 at 24 hours from start of shock compared to vehicle control. Histologic analysis demonstrated mild decreases in both perivascular pulmonary edema and follicular mesenteric lymph node hyperplasia in the tranexamic acid treatment group but also increased myocardial lymphocytic infiltration with necrosis and degeneration. Tranexamic acid was also associated with a small but significant increase in peripheral neutrophil count as well as a significant decrease in neutrophil aggregation in pulmonary tissue at six hours post-injury. These data thus demonstrate a mixed effect of tranexamic acid. While there was an improvement in pulmonary edema and a suppressive effect on several key inflammatory mediators, there was also increased myocardial degeneration and necrosis, which is possibly related to the pro-thrombotic effect of tranexamic acid.

Tissue injury suppresses fibrinolysis after hemorrhagic shock in nonhuman primates (rhesus macaque)

BACKGROUND

Hypoperfusion is associated with hyperfibrinolysis and early death from exsanguination, whereas tissue trauma is associated with hypofibrinolysis and delayed death from organ failure. We sought to elucidate the effects of injury patterns on fibrinolysis phenotypes using a nonhuman primate (NHP) model.

METHODS

NHPs were randomized to three injury groups (n = 8/group): 60 minutes severe pressure-targeted controlled hemorrhagic shock (HS); HS + soft tissue injury (HS+); or HS + soft tissue injury + femur fracture (HS++). Animals were resuscitated and monitored for 360 minutes. Blood samples were collected at baseline, end-of-shock, end-of-resuscitation (EOR), and T = 360 minutes for assessments of: severity of shock (lactate) and coagulation via prothrombin time, partial thromboplastin time, D-dimer, fibrinogen, antithrombin-III, von Willebrand factor, and viscoelastic testing (ROTEM). Results are reported as mean ± SEM; statistics: two-way analysis of variance and t-tests (significance: p < 0.05).

RESULTS

Blood loss, prothrombin time, partial thromboplastin time, antithrombin-III, fibrinogen, and von Willebrand factor were equivalent among groups and viscoelastic testing revealed few differences throughout the study. D-dimer increased approximately threefold, at EOR in the HS group, and at T = 360 minutes in the HS+ and HS++ groups (p < 0.05). At EOR, in the HS group compared with the HS+ and HS++ groups; the D-dimer-lactate ratio was twofold greater (2.2 ± 0.3 vs. 1.1 ± 0.3 and 1.1 ± 0.2, respectively; p < 0.05) and tissue factor-activated fibrin clot 30-minute lysis index was lower (98 ± 1% vs. 100 ± 0% and 100 ± 0%, respectively; p < 0.05).

CONCLUSION

NHPs in HS exhibit acute suppression of fibrinolysis in the presence of tissue injury. Additional assessments to more comprehensively evaluate the mechanisms linking tissue injury with the observed fibrinolysis shutdown response are warranted.

Intra-Abdominal Hypertension Causes Bacterial Growth in Lungs: An Animal Study

To study the effect of intra-abdominal hypertension (IAH) on the frequency of pneumonia with an experimental study, thirteen Sprague-Dawley rats were included. Eight out of thirteen animals were randomly assigned to receive 10 ml of benzalkonium chloride 0.2% (megacolon group) and five animals received 10 ml NaCl 0.9% (controls). Animals were anaesthetized by intramuscular delivery of ketamine. The incidence of positivity for bacteria lung tissue cultures and mesenteric lymph node cultures was assessed at the 21st day after animals' sacrification, or before in case of death. All megacolon group animals presented progressive increase of the abdomen and increased IAP (≥10 mmHg) whereas the frequency of their evacuations was almost eliminated. Controls presented normal evacuations, no sign of abdominal distention, and normal IAP. In megacolon group animals, there was evidence of significant amount of bacteria in lung cultures. In contrast, no bacteria were found in control animals.

A "CLEAN CASE" OF SYSTEMIC INJURY: MESENTERIC LYMPH AFTER HEMORRHAGIC SHOCK ELICITS A STERILE INFLAMMATORY RESPONSE

Postinjury multiple organ failure results from an inappropriate overwhelming immune response to injury. During trauma and hemorrhagic shock (T/HS), mesenteric ischemia causes gut mucosal breakdown with disruption of the intestinal barrier. It has been proposed that this releases the gut microbiota systemically via postshock mesenteric lymph (PSML), engendering infectious complications. Despite extensive investigation, no clear evidence has been presented for gut bacterial translocation after resuscitation from T/HS. However, such previous studies were limited by available technologies. More sensitive methods, such as quantitative polymerase chain reaction, have since emerged for detection of bacterial presence and danger-associated molecular patterns (DAMPs). Quantitative polymerase chain reaction was applied to PSML derived from a rat model of T/HS. No bacterial presence was detected in a series of 12 samples, whereas multiple lymph samples showed the presence of DAMPs after T/HS. Thus, we confirmed that bacterial translocation does not exist in PSML after resuscitation from T/HS-associated mesenteric ischemia. However, T/HS does increase the presence of mitochondrial DAMPs in PSML. These results support our current position that PSML elaborates remote organ injury by multiple inflammatory mechanisms, including lipid-mediated proinflammatory stimuli, and by contribution from gut-derived DAMPs.

Indications, techniques, and clinical outcomes of thoracic duct interventions in patients: a forgotten literature?

BACKGROUND

The evolution of the "gut-lymph concept" has promoted thoracic duct (TD) lymph drainage as a possible treatment to reduce systemic inflammation and end-organ dysfunction in acute illness. The aim was to review the published experience of thoracic duct interventions (TDIs) aimed at improving clinical outcomes.

METHODS

A search of three databases (MEDLINE, EMBASE, and EMBASE CLASSIC) over the last 60 y. The indications for intervention, the technique, and clinical outcomes were reviewed.

RESULTS

There were a wide range of indications for TDI. These included reducing rejection after transplantation, treating inflammatory diseases, and reducing chronic failure of the liver, kidney, and heart. The techniques included TD cannulation and lymphovenuous fistula. The outcomes were variable and often equivocal, and this appears to reflect poor design quality. There is clinical equipoise regarding a therapeutic role of (TD lymph drainage in acute pancreatitis, and probably other acute diseases.

CONCLUSIONS

Until well-designed clinical trials are undertaken, the clinical benefits of TDIs will remain promising, but uncertain.

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).

Lymph is not a plasma ultrafiltrate: a proteomic analysis of injured patients

Studies on animal models have documented a role for the water-soluble protein fraction of mesenteric lymph as a conduit from hemorrhagic shock to acute lung injury and postinjury multiple organ failure. We hypothesize that mesenteric lymph is not an ultrafiltrate of plasma and contains specific protein mediators that may predispose patients to acute lung injury/multiple organ failure. Mesenteric lymph and plasma were collected from critically ill or injured patients and from nine patients with lymphatic injuries, during semielective spine reconstruction, or immediately before organ donation. Proteomic analyses were performed through immunoaffinity depletion of the 14 most abundant plasma proteins and 1D gel electrophoresis followed by liquid chromatography coupled online with mass spectrometry analyses. Overall, 548 proteins were identified in the patients undergoing semielective surgery, of which 155 were uniquely present in the lymph. In addition, the postshock plasma proteome was characterized by peculiar features, suggesting that only a partial overlap exists between the plasma and mesenteric lymph from trauma patients. Differential proteins between the matched plasma and mesenteric lymph from trauma patients could be related to coagulopathy and hypercoagulability, cell lysis, proinflammatory responses and immune system activation, extracellular matrix remodeling, lymph-specific immunomodulation and vascular hypoactivity/neoangiogenesis, and energy/redox metabolic adaptation to trauma. In conclusion, the proteome of mesenteric lymph is biologically different (in qualitative and quantitative terms) than that of a mere plasma ultrafiltrate.

Uncovering the neuroenteric-pulmonary axis: vagal nerve stimulation prevents acute lung injury following hemorrhagic shock

AIMS

Trauma/hemorrhagic shock (T/HS) induced gut injury is known to initiate a systemic inflammatory response which can lead to secondary lung injury. We have shown that vagal nerve stimulation (VNS) protects intestinal epithelial integrity after a severe burn insult. We hypothesize that VNS will protect the lung from injury following T/HS by preventing intestinal barrier failure.

MAIN METHODS

Male Balb/c mice were subjected to a T/HS model with and without cervical VNS. Intestinal injury was evaluated by measuring changes in gut barrier function and tight junction protein localization. Lung injury was evaluated using histology and markers of lung inflammation. Using NF-kB-luciferase (NF-kB-luc) transgenic mice, NF-kb-DNA binding was measured by photon emission analysis at 4 after injury.

KEY FINDINGS

T/HS is associated gut injury characterized by histologic injury, increased epithelial permeability, and altered localization of gut tight junction proteins. Cervical VNS prevented the T/HS-induced changes in gut barrier integrity. Gut injury after T/HS was associated with acute lung injury at 24 h characterized by histologic injury, increased number of MPO positive stained cells and MPO enzymatic activity, and increased ICAM-1 expression in lung endothelium. VNS decreased T/HS-induced lung injury with a marked decrease in lung inflammation compared to T/HS alone. Lungs harvested from NF-kB-luc mice at 4h post VNS+T/HS demonstrated decreased DNA binding of NF-kB compared to T/HS alone as measured by changes in bioluminescence.

SIGNIFICANCE

VNS is effective in protecting against acute lung injury caused by hemorrhagic shock through its ability to prevent gut barrier dysfunction.

The 5-lipoxygenase pathway is required for acute lung injury following hemorrhagic shock

The cellular and biochemical mechanisms leading to acute lung injury (ALI) and subsequent multiple organ failure are only partially understood. To study the potential role of eicosanoids, particularly leukotrienes, as possible mediators of ALI, we used a murine experimental model of ALI induced by hemorrhagic shock after blood removal via cardiac puncture. Neutrophil sequestration, as shown by immunofluorescence and protein leakage into the alveolar space were measured as markers of injury. We used liquid chromatography coupled to tandem mass spectrometry to unequivocally identify several eicosanoids in the bronchoalveolar lavage fluid of experimental animals. MK886, a specific inhibitor of the 5-lipoxygenase (5-LO) pathway, and transgenic mice deficient in 5-LO were used to determine the role of this enzymatic pathway in this model. Leukotriene B4 and leukotriene C4 were consistently elevated in shock-treated mice compared with sham-treated mice. MK886 attenuated neutrophil infiltration and protein extravasation induced by hemorrhagic shock. 5-Lipoxygenase-deficient mice showed reduced neutrophil infiltration and protein extravasation after shock treatment, indicating greatly reduced lung injury. These results support the hypothesis that 5-LO, most likely through the generation of leukotrienes, plays an important role in the pathogenesis of ALI induced by hemorrhagic shock in mice. This pathway could represent a new target for pharmacological intervention to reduce lung damage following severe primary injury.

Cross-transfusion of postshock mesenteric lymph provokes acute lung injury

OBJECTIVE

Substantial investigation has implicated mesenteric lymph as the mechanistic link between gut ischemia/reperfusion (I/R) and distant organ injury. Specifically, lymph diversion prevents acute lung injury (ALI) in vitro, and bioactive lipids and proteins isolated from postshock mesenteric lymph (PSML) maintain bioactivity in vitro. However, Koch's postulates remain to be satisfied via direct cross-transfusion into a naïve animal. We therefore hypothesized that real time cross-transfusion of postshock mesenteric lymph provokes acute lung injury.

METHODS

One set of Sprague-Dawley rats (lymph donors) was anesthetized, with the mesenteric lymph ducts cannulated and exteriorized to drain freely into a siliconates plastic cup; concurrently, a second group of rats ( lymph recipients) was anesthetized, with a cannula inserted into the animal's right internal jugular vein. Blood was removed from the donor rats to induce hemorrhagic shock (MAP of 35 mmHg × 45 min). The recipient rats were positioned 10 cm below the plastic cup, which emptied into the jugular vein cannula. Thus, mesenteric lymph from the shocked donor rat was delivered to the recipient rat at the rate generated during shock and the subsequent 3 h of resuscitation.

RESULTS

Neutrophil (PMN) accumulation in the lungs was substantially elevated in the postshock lymph cross-transfusion group compared to both sham lymph cross-transfusion and instrumented control (MPO: 9.42 ± 1.55 versus 2.81 ± 0.82 U/mg lung tissue in postshock versus sham lymph cross-transfusion, n = 6 in each group, P = 0.02). Additionally, cross-transfusion of PSML induced oxidative stress in the lung (0.21 ± 0.03 versus 0.10 ± 0.01 micromoles MDA per mg lung tissue in lymph cross-transfusion versus instrumented control, n = 6 in each group, P = 0.046). Furthermore, transfusion of PSML provoked lung injury (BAL protein 0.77 ± 0.18 versus 0.15 ± 0.02 mg/mL protein in BALF, postshock versus sham lymph cross-transfusion, n = 6 in each group, P = 0.004).

CONCLUSION

Cross-transfusion of PSML into a naïve animal leads to PMN accumulation and provokes ALI. These data provide evidence that postshock agents released into mesenteric lymph are capable of provoking distant organ injury.

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.

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.

Proteomic profiling of the mesenteric lymph after hemorrhagic shock: Differential gel electrophoresis and mass spectrometry analysis

Experiments show that upon traumatic injury the composition of mesenteric lymph changes such that it initiates an immune response that can ultimately result in multiple organ dysfunction syndrome (MODS). To identify candidate protein mediators of this process we carried out a quantitative proteomic study on mesenteric lymph from a well characterized rat shock model. We analyzed three animals using analytical 2D differential gel electrophoresis. Intra-animal variation for the majority of protein spots was minor. Functional clustering of proteins revealed changes arising from several global classes that give novel insight into fundamental mechanisms of MODS. Mass spectrometry based proteomic analysis of proteins in mesenteric lymph can effectively be used to identify candidate mediators and loss of protective agents in shock models.

A novel mechanism for neutrophil priming in trauma: potential role of peritoneal fluid

BACKGROUND

We sought to determine the effect of peritoneal fluid from a novel animal model of abdominal compartment syndrome (ACS) on the proinflammatory status of polymorphonuclear leukocytes (PMNs) and monocytes. We hypothesize that peritoneal fluid is a potential priming and/or activating agent for PMNs/monocytes.

METHODS

ACS was induced in female Yorkshire swine, and peritoneal fluid was collected at the time of decompressive laparotomy. Naïve PMNs/monocytes were primed and/or activated with peritoneal fluid, phosphatidylcholine (PAF) plus peritoneal fluid, peritoneal fluid plus n-formyl-met-leu-phe (fMLP), and peritoneal fluid plus phorbol 12-myristate 13-acetate (PMA). Activation was determined by surface marker expression of integrins (CD11b an CD18) and selectins (CD62L). Additionally, proinflammatory cytokines in peritoneal fluid were analyzed.

RESULTS

Peritoneal fluid did not activate PMNs but increased CD11b expression on monocytes. When used as a primer for fMLP- or PMA-induced activation, peritoneal fluid significantly increased CD11b and CD18 expression on PMNs and monocytes. Peritoneal fluid collected at 6 and 12 h post decompressive laparotomy had similar effects. Interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) levels were increased in peritoneal fluid.

CONCLUSION

Peritoneal fluid represents a primer for PMNs/monocytes and seems to act through receptor-dependent and receptor-independent pathways. Strategies to reduce the amount of peritoneal fluid may decrease the locoregional and systemic inflammatory response by reducing priming and activation of neutrophils/monocytes.

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.

Hemostatic properties of a venomic protein in rat organ trauma

Previous in vitro work characterized the protease Q8009 isolated from the venom of the Australian brown snake Pseudonaja textilis textilis with Factor Xa-like activity and hemostatic properties. The purpose of the work described here characterizes the in vivo hemostatic properties in a rat model of parenchymatous organ injury. The key parameters of activity included reduction in time-to-hemostasis and total volume of blood loss in spleen, liver and kidney wound models in rats. The surgical protocols involved exposure of the organs via a midline abdominal laparotomy. Using a clean metal template with 6, 6.5, 9 mm holes for spleen, liver and kidney, respectively, a predetermined volume of the organ was gently extruded through the template hole and excised with a razor blade. About 50 to 75 microL of collagen matrix with the different test solutions was applied to the wounds. Blood was collected and at the end of the procedure animals were humanely sacrificed with an anesthetic overdose. Determination of blood was performed using the hematin assay using a standard curve. Blood loss per minute and total blood loss were calculated. Results from the studies demonstrated that the application of Q8009 and collagen matrix to surgical wounds significantly reduced the total amount of blood loss and the time-to-hemostasis. In the spleen wound model, Q8009 at 100, 250 and 1000 microg/ml significantly reduced (p<0.001) the total volume of blood lost relative to thrombin and reduced the time-to-hemostasis by 25-50%, as compared to 7% by thrombin. In the liver wound model, Q8009 at 250 and 1000 microg/ml significantly reduced (p<0.001) the total volume of blood lost relative to thrombin and reduced the time-to-hemostasis from 10.5 min by thrombin to 5.6 min with Q8009. In the kidney wound model, Q8009 at 250 microg/ml significantly reduced (p<0.05) the total volume of blood lost and reduced the time-to-hemostasis by 25% when compared to thrombin. The hemostasis levels were consistent with previous findings in skin wound rat models where Q8009 consistently reduced the total volume of blood lost and shortened time-to-hemostasis. Application of Q8009 plus collagen matrix significantly reduced the volume of total blood loss and time-to-hemostasis in rat surgical organ wound models induced bleeding, as compared to a commercially available hemostat device. The protein Q8009 has greater capacity to reduce blood loss and shorten time-to-hemostasis; highly desirable properties where rapid hemostasis is needed in surgical wounds in parenchymatous organs.

Gelsolin is depleted in post-shock mesenteric lymph

BACKGROUND

Gelsolin is a plasma protein that functions to depolymerize actin filaments preventing capillary plug formation following tissue injury. It also functions to mediate the inflammatory response by binding proinflammatory lipids such as lysophosphatidic acid, sphingosine-1-phosphate and phosphoinositides. Clinically, reduced gelsolin concentrations have been associated with increased mortality in critically ill, trauma, and burn patients. We have previously shown that following hemorrhagic shock with splanchnic hypoperfusion, mesenteric lymph contains lipid components that cause neutrophil and EC activation and that protein concentrations are severely diluted due to resuscitation. We hypothesized that lipid binding proteins such as gelsolin may be depleted after trauma/hemorrhagic shock leading to increased lipid bioactivity.

METHODS

Shock was induced in SD rats by controlled hemorrhage and the mesenteric duct cannulated for lymph collection. Resuscitation was performed by infusing 2x SB volume in NS over 30 min, followed by 1/2 SB volume over 30 min, then 2x SB volume in NS over 60 min. Pre and post-shock lymph was loaded at equal protein concentrations on 2D-gels, followed by trypsin digestion and identification with mass spectrometry (MS-MS). Proteomics data were confirmed with Western blotting then quantitated by densitometry. Analysis of variance was used evaluate statistical data.

RESULTS

Gelsolin decreased in mesenteric lymph following hemorrhagic shock.

CONCLUSIONS

Gelsolin is found at high levels (comparable to plasma) in mesenteric lymph. Following hemorrhagic shock, gelsolin levels decrease significantly, possibly due to consumption by the actin scavenging system. The magnitude of this change in concentration could release lipid bioactivity and predispose the lung and other organs to capillary injury.

Postshock mesenteric lymph induces endothelial NF-kappaB activation

BACKGROUND

Posthemorrhagic shock mesenteric lymph (PSML) has been shown to activate pulmonary endothelial cells and cause lung injury. Although multiple mediators may be involved, most of these effects are mediated by nuclear factor-kappa B (NF-kappaB) activation. Degradation of the inhibitor of kappa B (IkappaB) is a key regulatory step in the activation of NF-kappaB. We therefore hypothesized that PSML would cause IkappaB degradation with subsequent NF-kappaB phosphorylation and nuclear translocation.

METHODS

Mesenteric lymph was collected from male rats before shock and each hour after shock for up to 3 h (n = 5). Buffer (control), buffer + 10% (v/v) lymph, or buffer + tumor necrosis factor (10 ng/mL) were incubated with human pulmonary endothelial cells for 30 min and then lysed. Immunoblots of lysates were probed for IkappaB and phospho-p65. Immunohistochemistry was performed on cells grown on glass slides and then treated as above with the third PSML sample. Cells were fixed and then probed for p65. Statistical analysis was performed with Student's t-test and analysis of variance with significance was set at P < 0.05.

RESULTS

Western blots of cell lysates for IkappaB demonstrated a steady decrease in total IkappaB with each lymph sample. Phosphorylation of NF-kappaB , p65 component, steadily increased with each PSML sample, with a maximum reached during the third PSML sample, which also significantly increased translocation of NF-kappaB to the nucleus.

CONCLUSION

Postshock mesenteric lymph bioactivity is mediated by pathways which involved IkappaB degradation. These pathways offer novel off targets for clinical intervention to prevent the distal organ injury caused by postinjury hemorrhagic shock.

Hemostatic properties of a venomic protein in rodent dermal injuries

Hemostatic properties of a factor Xa-like protease (Q8009) from the Australian snake Pseudonaja textilis textilis were determined. In tail-tip transection and dermal incision (hind limb) models, reagents were applied with collagen matrix. Blood was collected on filter paper chads for 12 one-minute intervals or until hemostasis. Determination of blood loss was performed using the hematin content and reported as blood loss per minute and total blood lost. Results from the studies demonstrated that the addition of the protease Q8009 and collagen matrix significantly reduced the volume of blood loss and shortened the time-to-hemostasis. In the dermal incision model, Q8009 (100, 250 and 1000 microg/ml) plus collagen matrix significantly reduced (p<0.001) the volume of blood lost relative to Thrombin and shortened the time-to-hemostasis to 2.0 min compared to 4.77 min with Thrombin. In the tail-tip transection model when Q8009 was mixed with a collagen matrix there was no significant reduction in blood loss, when compared to Thrombin plus collagen matrix. However, when injured tail-tips were held in Q8009 (1000 microg/ml) solution, there was a significant reduction (p<0.001) in blood loss (5.88 microl) versus that of Thrombin at 58.0 mul, and time-to-hemostasis was reduced from 11 min with Thrombin to 3 min when the Q8009 solution was used. In these studies, topical application of the venomic protease Q8009 significantly reduced total blood loss with a shorter time-to-hemostasis relative to Thrombin.

Acute ethanol exposure combined with burn injury enhances IL-6 levels in the murine ileum

BACKGROUND

Recent studies suggest that ethanol use imposes a greater risk of trauma-associated intestinal injury than trauma alone. The initiating and regulatory factors for multiple organ dysfunction syndromes are not well defined, yet evidence points to the gut as a possible trigger of the systemic inflammatory cascade as well as a potential source of cytokines. In the current study, we hypothesized that ethanol administration would alter cytokine levels and intestinal infiltration by neutrophils within the ileum of mice exposed to burn injury (15% total body surface of dorsal skin).

METHODS

Ileal samples were collected for histological assessment, myeloperoxidase quantitation and the protein presence of tumor necrosis factor alpha (TNFalpha), interleukin (IL-) 6, macrophage inflammatory protein-2 (MIP-2; CXCL2) and the anti-inflammatory cytokine, IL-10. Additional ileal tissue samples were examined for localization of the IL-6 immunoreactivity.

RESULTS

We did not detect statistically significant cytokine/chemokine differences (MIP-2 and IL-10) between sham control and treatment conditions at either 2 or 24 hours. However, there was a significant decrease in TNFalpha at 24 hours in both burn injury alone and in combination with ethanol treatment conditions (p < 0.05). In addition, there was an increase in IL-6 levels at 24 hours in intestinal tissue obtained from mice subjected to a combination of acute ethanol and burn injury, compared to the mice receiving burn or sham injury (p < 0.001). Ileal homogenate increases in IL-6 at 24 hours were concurrent with decreased villus height in the ileum, but no discernable changes in neutrophil infiltration (myeloperoxidase activity levels) at either 2 or 24 hours. Additional immunocytochemical localization studies of ileal tissue revealed that there was a substantial increase of IL-6 in intestinal enterocytes subjected to both burn injury alone, or in combination with acute ethanol exposure.

CONCLUSIONS

The present study suggests that acute ethanol exposure combined with burn injury enhances levels of IL-6 protein in the ileum. The enhanced levels of ileal IL-6 are likely due to enterocyte production of the cytokine.

Normal mesenteric lymph blunts the pulmonary inflammatory response to endotoxin

BACKGROUND

Mesenteric lymph may provide the mechanistic link between gut ischemia and acute lung injury after hemorrhagic shock (HS). Studies have focused on the toxic mediators that develop in the post-shock mesenteric lymph (PSML). However, a complementary possibility is that there is loss of protective mediators found in pre-shock normal mesenteric lymph (NML) after HS. We hypothesize that NML protects against inflammatory insults to the pulmonary endothelium and that this effect is lost in PSML.

MATERIALS AND METHODS

Primary human pulmonary endothelial cells (HMVECs) were incubated with NML or PSML collected from rats subjected to HS and resuscitation and then stimulated with 20 ng/mL LPS. ICAM-1 surface expression was measured by flow cytometry. In subsequent experiments, lipoproteins were extracted from NML before incubation and LPS-induced ICAM-1 expression determined.

RESULTS

Mean fluorescent intensity (MFI) of LPS-induced ICAM-1 in NML and PSML treated HMVECs were 10.1 +/- 2.3 versus 27.7 +/- 0.83, respectively (P < 0.05). This represented at 71% decrease in ICAM-1 expression by NML compared to ICAM-1 expression in LPS-induced controls (MFI: 34.6 +/- 6.9). Lipoprotein extraction from NML abolished this protective effect (MFI: 31.2 +/- 5.3 versus Control + LPS: 33.5 +/- 3.6, P > 0.05). Baseline ICAM-1 levels were not significantly different among control, NML, and PSML groups.

CONCLUSION

Lipoproteins in NML contain anti-inflammatory properties that decrease ICAM-1 expression induced by LPS in pulmonary endothelium. Decreased protective lipoproteins after HS and resuscitation may contribute to the toxicity associated with PSML from the ischemic gut.

Direct peritoneal resuscitation from hemorrhagic shock: effect of time delay in therapy initiation

BACKGROUND

After conventional resuscitation from hemorrhagic shock, splanchnic microvessels progressively constrict, leading to impairment of blood flow. This occurs despite restoration and maintenance of central hemodynamics. The authors' recent studies have demonstrated that topical and continuous ex vivo exposure of the gut microvasculature to a glucose-based clinical peritoneal dialysis solution (Delflex), as a technique of direct peritoneal resuscitation (DPR), can prevent these postresuscitation events when initiated simultaneously with conventional resuscitation. This study aimed to determine whether DPR applied after conventional resuscitation reverses the established postresuscitation intestinal vasoconstriction and hypoperfusion.

METHODS

Male Sprague-Dawley rats were bled to 50% of baseline mean arterial pressure and resuscitated intravenously over 30 minutes with the shed blood returned plus two times the shed blood volume of saline. Initiation of ex vivo, topical DPR was delayed to 2 hours (group 1, n = 8), or to 4 hours (group 2, n = 8), respectively, after conventional resuscitation. Intravital microscopy and Doppler velocimetry were used to measure terminal ileal microvascular diameters of inflow A1 and premucosal A3 (proximal pA3, distal dA3) arterioles and blood flow in the A1 arteriole, respectively. Maximum arteriolar dilation capacity was obtained from the topical application, in the tissue bath, of the endothelium-independent nitric oxide-donor sodium nitroprusside (10M).

RESULTS

Hemorrhagic shock caused a selective vasoconstriction of A1 (-24.1% +/- 2.15%) arterioles from baseline, which was not seen in A3 vessels. This caused A1 blood flow to drop by -68.6% of the prehemorrhage value. Conventional resuscitation restored and maintained hemodynamics in all the animals without additional fluid therapy. In contrast, there was a generalized and progressive postresuscitation vasoconstriction of A1 (-21.7%), pA3 (-18.5%), and dA3 (-18.7%) vessels. The average postresuscitation A1 blood flow was -49.5% of the prehemorrhage value, indicating a persistent postresuscitation hypoperfusion. Direct peritoneal resuscitation reversed the postresuscitation vasoconstriction by 40.9% and enhanced A1 blood flow by 112.9% of the respective postresuscitation values.

CONCLUSIONS

Delayed DPR reverses the gut postresuscitation vasoconstriction and hypoperfusion regardless of the initiation time. This occurs without adverse effects on hemodynamics. Direct peritoneal resuscitation-mediated enhancement of tissue perfusion results from the local effects from the vasoactive components of the Delflex solution, which are hyperosmolality, lactate buffer anion, and, to a lesser extent, low pH. The molecular mechanism of this vasodilation effect needs further investigation.

The female intestine is more resistant than the male intestine to gut injury and inflammation when subjected to conditions associated with shock states

Having documented that proestrus female rats are more resistant to shock-induced acute gut and hence lung injury than male rats, we tested the hypothesis that the female gut is more resistant to injury and produces less of an inflammatory response than the male gut when exposed to conditions associated with shock states (hypoxia and acidosis) utilizing the ex vivo Ussing chamber system. Ileal mucosal membranes harvested from normal male and female rats mounted in Ussing chamber systems were exposed to normoxia or 40 min of hypoxia at a normal pH (pH 7.3) or acidosis (pH 6.8). Cytokine and nitric oxide levels in the serosal compartment of the Ussing chamber were measured at the end of the 3-h experimental period to assess the immunoinflammatory response, whereas FITC-dextran (mol wt 4,300) was employed to assess barrier function. Histomorphological changes were used to quantitate gut mucosal injury. Hypoxia, acidosis, or hypoxia plus acidosis was associated with a significant increase in proinflammatory cytokine production [interleukin (IL)-6, tumor necrosis factor, and macrophage inflammatory protein (MIP)-2] by the male compared with the female intestinal segments. In contrast, the female gut manifested a higher anti-inflammatory response (nitric oxide and IL-10) and improved intestinal barrier function as well as less evidence of mucosal injury than the male intestinal segments. Administration of estradiol or the testosterone receptor antagonist, flutamide, to male rats abrogated the increase in gut injury and the increased IL-6 and MIP-2 response observed after hypoxia plus acidosis. These results suggest that gender differences in the ex vivo intestinal response to stresses, such as hypoxia and acidosis, exist and that the administration of estradiol or blockade of the testosterone receptor to male rats mitigates these gender differences.

Factors in intestinal lymph after shock increase neutrophil adhesion molecule expression and pulmonary leukosequestration

BACKGROUND

Because the ischemic gut may produce factors that initiate systemic inflammation, we tested the hypothesis that factors released from the gut into the mesenteric lymphatics increase neutrophil (PMN) adhesion molecule expression after trauma and shock.

METHODS

At 1 and 4 hours after hemorrhagic shock (30 mm Hg x 90 minutes) plus trauma (laparotomy) (T/HS) or sham-shock (T/SS), with or without mesenteric lymph duct ligation, PMN CD11b and CD18 expression was assessed in male rats. In additional rats, mesenteric lymph samples were tested for their ability to increase PMN CD11b expression in vitro. Lastly, at 4 hours after T/SS or T/HS with or without lymph duct ligation, pulmonary PMN sequestration was measured.

RESULTS

Compared with T/SS rats, T/HS was associated with up-regulation of PMN CD11b and CD18 expression, which was largely prevented by ligation of the mesenteric lymph duct (p < 0.01). Lymph duct ligation also prevented T/HS-induced pulmonary leukocyte sequestration (p < 0.01). In addition, mesenteric lymph from rats subjected to T/HS but not T/SS increased CD11b expression (p < 0.01).

CONCLUSION

Factors produced or released by the postischemic intestine and carried in the mesenteric lymph appear responsible for PMN activation and pulmonary PMN sequestration after an episode of T/HS.

Influence of fructooligosaccharides on Peyer's patch lymphocyte numbers in healthy and endotoxemic mice

OBJECTIVE

The purpose of this study was to determine whether fructooligosaccharides (FOS) exert an immunomodulating effect on Peyer's patches (PP), the main inductive site of the intestinal immune system. We investigated the effects of FOS in healthy and endotoxemic animals.

METHODS

Six-week-old female Balb/c mice were fed a control diet or a diet supplemented with 10% FOS over a period of 16 d. To induce endotoxemia, mice were challenged intraperitoneally with lipopolysaccharide (LPS) on day 15. PP were excised from mice, and lymphocyte subpopulations (B lymphocytes, T lymphocytes, CD4(+) cells, and CD8(+) cells) were determined by flow cytometry.

RESULTS

The FOS-enriched diet increased the total cell yield in healthy and endotoxemic mice (P < 0.001). Similarly, B lymphocytes were increased in both groups (P < 0.001). In contrast, T lymphocytes were unaltered in healthy mice but increased in LPS-challenged mice after FOS enrichment (P < 0.001). In endotoxemic mice but not in control animals, the increase of CD4(+) cells (P < 0.001) was more pronounced than that of CD8(+) cells (P < 0.001), thus increasing the CD4:CD8 ratio (P < 0.01).

CONCLUSION

FOS showed an immunostimulating effect on PP lymphocytes under healthy and endotoxemic conditions. Thus it can be concluded that FOS administration affects not only the large intestine but also the main inductive part of the mucosal immune system in the small intestine.