Christian Hierholzer

Biphasic response to gut manipulation and temporal correlation of cellular infiltrates and muscle dysfunction in rat

BACKGROUND Surgical manipulation of the intestine results in the massive movement of leukocytes into the intestinal muscularis at 24 hours. This is associated with muscle inhibition. The aim of this study was to temporally associate leukocyte extravasation with ileus after surgical manipulation. METHODS Rats underwent a simple manipulation of the small bowel and were killed at various times (0, 0.25, 0.5, 1, 3, 6, 12, and 24 hours) postoperatively. Jejunal circular-muscle contractile activity was assessed in a standard organ bath. Both extravasating and resident leukocytes were immunohistochemically stained in muscularis whole mounts. RESULTS Contractile activity was significantly reduced immediately after surgery, but rapidly returned to control levels at 3 hours. After recovery, muscle function decreased at 12 and 24 hours (41% and 81%, respectively). The resident muscularis macrophage network demonstrated cellular activation 1 hour postoperatively. The number of leukocytes increased over time (neutrophils, 67.5-fold; monocytes, 98.2-fold; and mast cells, 47-fold at 24 hours). CONCLUSIONS The functional results demonstrate a biphasic response in the suppression of muscle activity after surgical manipulation. Regression analysis (r2 = 0.998) of the temporal development of leukocyte infiltration and the protracted phase of muscle inhibition provides evidence for a correlation between cellular inflammation and postoperative dysmotility.

Molecular and functional contractile sequelae of rat intestinal ischemia/reperfusion injury.

BACKGROUND Pathophysiological states that produce intestinal ischemia/reperfusion injury (I/R) initiate an inflammatory cascade and cause ileus. The aims of this study were to investigate the local cellular responses and molecular mechanisms, which contribute to intestinal dysmotility after selective intestinal I/R injury. METHODS ACI rats were subjected to 75 min SMA clamp-induced ischemia followed by reperfusion and were killed at 0 min, 30 min, and 24 hr. Whole mounts of the jejunum were used to immunohistochemically quantify alterations in leukocytes, and circular muscle strips were used to assess organ bath muscle function. Muscularis and mucosa extracts were isolated from the intestine and used for reverse transcription assisted polymerase chain reaction mRNA measurements of granulocyte-colony stimulating factor and interleukin-6, and for determination of nuclear factor kappa B and Stat3 activation. RESULTS Intestinal I/R injury resulted in the significant recruitment of neutrophils and monocytes into the intestinal muscularis and a functional suppression in jejunal circular muscle contractions. These I/R injury induced cellular responses were preceded by the molecular activation of nuclear factor kappa B, up-regulation of granulocyte colony-stimulating factor and interleukin-6 mRNA and phosphorylation of the downstream signaling and transcription factor Stat3. CONCLUSIONS I/R injury evokes a molecular and cellular inflammatory response within the intestinal muscularis that is associated with a subsequent decrease in intestinal motility.

Interleukin-6 production in hemorrhagic shock is accompanied by neutrophil recruitment and lung injury

Hemorrhagic shock (HS) initiates an inflammatory cascade that includes the production of cytokines and recruitment of neutrophils (PMN) and may progress to organ failure, inducing acute respiratory distress syndrome (ARDS). To examine the hypothesis that interleukin-6 (IL-6) contributes to PMN infiltration and lung damage in HS, we examined the lungs of rats subjected to unresuscitated and resuscitated HS for the production of IL-6 and activation of Stat3. Using semiquantitative RT-PCR, we found a striking increase in IL-6 mRNA levels only in resuscitated HS, with peak levels observed 1 h after initiation of resuscitation. Increased IL-6 protein expression was localized to bronchial and alveolar cells. Electrophoretic mobility shift assay of protein extracts from shock lungs exhibited an increase in Stat3 activation with kinetics similar to IL-6 mRNA. In situ DNA binding assay determined Stat3 activation predominantly within alveoli. Intratracheal instillation of IL-6 alone into normal rats resulted in PMN infiltration into lung interstitium and alveoli, marked elevation of bronchoalveolar lavage cellularity, and increased wet-to-dry ratio. These findings indicate that IL-6 production and Stat3 activation occur early in HS and may contribute to PMN-mediated lung injury, including ARDS after HS.Hemorrhagic shock (HS) initiates an inflammatory cascade that includes the production of cytokines and recruitment of neutrophils (PMN) and may progress to organ failure, inducing acute respiratory distress syndrome (ARDS). To examine the hypothesis that interleukin-6 (IL-6) contributes to PMN infiltration and lung damage in HS, we examined the lungs of rats subjected to unresuscitated and resuscitated HS for the production of IL-6 and activation of Stat3. Using semiquantitative RT-PCR, we found a striking increase in IL-6 mRNA levels only in resuscitated HS, with peak levels observed 1 h after initiation of resuscitation. Increased IL-6 protein expression was localized to bronchial and alveolar cells. Electrophoretic mobility shift assay of protein extracts from shock lungs exhibited an increase in Stat3 activation with kinetics similar to IL-6 mRNA. In situ DNA binding assay determined Stat3 activation predominantly within alveoli. Intratracheal instillation of IL-6 alone into normal rats resulted in PMN infiltration into lung interstitium and alveoli, marked elevation of bronchoalveolar lavage cellularity, and increased wet-to-dry ratio. These findings indicate that IL-6 production and Stat3 activation occur early in HS and may contribute to PMN-mediated lung injury, including ARDS after HS.

A novel nitric oxide scavenger decreases liver injury and improves survival after hemorrhagic shock

We tested the ability of a nitric oxide (NO) scavenger to reduce tissue injury in a rodent model of hemorrhagic shock. Rats were hemorrhaged to a mean arterial blood pressure (MAP) of 40 mmHg and then resuscitated when either 30% of their shed blood had been returned (group 1) or after 100 min of continuous shock (group 2). Selected animals were treated with the NO scavenger NOX (30 mg. kg(-1). h(-1)) infused over 4 h. Hemorrhaged rats had a lower MAP after resuscitation compared with sham-shock control rats. NOX treatment significantly increased MAP after resuscitation from hemorrhage. Hemorrhagic shock also increased liver injury as reflected by elevated ornithine carbamoyltransferase (OCT) plasma levels, and NOX treatment significantly reduced OCT release. In addition, NOX was associated with significantly decreased hepatic neutrophil infiltration and improved 24-h survival (n = 8 of 9) compared with saline-treated shock animals (n = 3 of 9). These data suggest that excess NO mediates shock-induced tissue injury and that suppression of NO availability with NO scavengers may reduce the pathophysiological sequelae of severe hemorrhage.

Characterization of the expression of inducible nitric oxide synthase in rat and human liver during hemorrhagic shock.

It has been previously shown that the inducible nitric oxide (NO) synthase (iNOS; NOS-2) is elevated after hemorrhage, and that iNOS-derived NO participates in the upregulation of inflammation as well as lung and liver injury postresuscitation from shock. The purpose of this study was to elucidate the time course of iNOS mRNA expression, as well as the cellular and subcellular localization of iNOS protein in the liver posthemorrhage in rats subjected to varying durations of hemorrhagic shock (HS; mean arterial blood pressure [MAP] = 40 mmHg) with or without resuscitation. Expression of iNOS mRNA in rat liver by real-time reverse transcriptase (RT)-PCR demonstrated iNOS upregulation in shocked animals as compared with their sham counterparts as early as 60 min after the initiation of hemorrhage. By 1 h of HS, iNOS protein was detectable in rat liver by immunofluorescence, and this expression increased with time. Immunofluorescence localized iNOS primarily to the hepatocytes, and in particular to hepatocytes in the centrilobular regions. This analysis, confirmed by immunoelectron microscopy, revealed that iNOS colocalizes with catalase, a peroxisomal marker. Furthermore, we determined that iNOS mRNA is detectable by RT-PCR in liver biopsies from human subjects with HS (MAP < 90 mmHg) associated with trauma (n = 18). In contrast, none of the seven nontrauma surgical patients studied had detectable iNOS mRNA in their livers. Collectively, these results suggest that hepatic iNOS expression, associated with peroxisomal localization, is an early molecular response to HS in experimental animals and possibly in human patients with trauma with HS.

G-CSF instillation into rat lungs mediates neutrophil recruitment, pulmonary edema, and hypoxia.

Activated neutrophils (PMN) have been implicated in the pathogenesis of adult respiratory distress syndrome (ARDS). Granulocyte colony‐stimulating factor (G‐CSF) is essential for PMN production and activation of PMN functions. We have recently shown that levels of G‐CSF mRNA in a rat model of hemorrhagic shock correlated with severity of shock, PMN infiltration, pulmonary edema, and hypoxia. To determine whether increased tissue levels of G‐CSF contribute to PMN recruitment and PMN‐mediated injury, we instilled G‐CSF into the lungs by intratracheal injection. Animals treated with G‐CSF became hypoxic, hypocapnic, and alkalotic and demonstrated increased BAL fluid cellularity compared with control animals. The wet‐to‐dry ratio increased significantly after G‐CSF instillation and peaked at 12 h. Histological examination of the lungs from G‐CSF‐treated rats revealed marked edema and increased PMN within the interstitium and alveoli. These results indicate that the presence of G‐CSF alone in the lung can lead to recruitment of PMN, lung injury, and impaired pulmonary function, suggesting that local production of G‐CSF may contribute to the development of lung damage and possibly ARDS in the setting of resuscitated hemorrhagic shock. J. Leukoc. Biol. 63: 169–174; 1998.

Association between a single-pass whole-body computed tomography policy and survival after blunt major trauma: a retrospective cohort study

IntroductionSingle-pass, whole-body computed tomography (pan-scan) remains a controversial intervention in the early assessment of patients with major trauma. We hypothesized that a liberal pan-scan policy is mainly an indicator of enhanced process quality of emergency care that may lead to improved survival regardless of the actual use of the method.MethodsThis retrospective cohort study included consecutive patients with blunt trauma referred to a trauma center prior to (2000 to 2002) and after (2002 to 2007) the introduction of a liberal single-pass pan-scan policy. The overall mortality between the two periods was compared and stratified according to the availability and actual use of the pan-scan. Logistic regression analysis was employed to adjust mortality estimates for demographic and injury-related independent variables.ResultsThe study comprised 313 patients during the pre-pan-scan period, 223 patients after the introduction of the pan-scan policy but not undergoing a pan-scan and 608 patients undergoing a pan-scan. The overall mortality was 23.3, 14.8 and 7.9% (P < 0.001), respectively. By univariable logistic regression analysis, both the availability (odds ratio (OR) 0.57, 95% confidence interval (CI): 0.36 to 0.90) and the actual use of the pan-scan (OR 0.28, 95% CI: 0.19 to 0.42) were associated with a lower mortality. The final model contained the Injury Severity Score, the Glasgow Coma Scale, age, emergency department time and the use of the pan-scan. 2.7% of the explained variance in mortality was attributable to the use of the pan-scan. This contribution increased to 7.1% in the highest injury severity quartile.ConclusionsIn this study, a liberal pan-scan policy was associated with lower trauma mortality. The causal role of the pan-scan itself must be interpreted in the context of improved structural and process quality, is apparently moderate and needs further investigation with regard to the diagnostic yield and changes in management decisions. (The Pan-Scan for Trauma Resuscitation [PATRES] Study Group, ISRCTN35424832 and ISRCTN41462125)

Hemorrhagic shock results in intestinal muscularis intercellular adhesion molecule (ICAM-1) expression, neutrophil infiltration, and smooth muscle dysfunction

Abstract Intestinal stasis followed by mucosal barrier breakdown and the generation of locally produced cytokines has been proposed as the cause of systemic infection and multiple organ failure following hemorrhagic shock. The aim of this study was to investigate the underlying mechanisms of impaired intestinal muscle function leading to ileus following hemorrhagic shock. Rats were subjected to severe hemorrhagic shock (mean arterial pressure 40 mm Hg) followed by resuscitation and were killed early at 4 h or late at 24 h. Other groups consisted of control and sham animals. Intercellular adhesion molecule (ICAM-1) mRNA levels were significantly elevated in the muscularis but not in the mucosa using the semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR). There was a marked infiltration of neutrophils into the muscularis early and late after shock. Furthermore, smooth muscle contractility in response to bethanechol was significantly decreased, being more pronounced in the early group. Immunohistochemistry revealed signal for ICAM-1 in the muscularis microvasculature and on infiltrating cells. These results suggest that the expression of ICAM-1 within the muscularis vasculature after hemorrhagic shock promotes the local recruitment of leukocytes and that this inflammatory response is accompanied by a subsequent impairment of intestinal contractility.

A nitric oxide scavenger protects against pulmonary inflammation following hemorrhagic shock.

Hemorrhagic shock (HS) elicits an inflammatory response characterized by increased cytokine production and recruitment of PMN which we previously found to be iNOS dependent. In this study we attempted to remove excess induced-NO by administration of the NO scavenger, NOX, with the goal of suppressing proinflammatory signaling and reducing organ damage. Rats subjected to HS (MAP = 40 mmHg for 100 min) followed by resuscitation and examined 24 h later demonstrated histological signs of lung injury including pulmonary edema as well as an 8.6-fold increase in MPO-positive PMN. These events were accompanied by a 3.9-fold increase in mRNA levels for IL-6, 3.7-fold for ICAM-1, 3.5-fold for IL-1&bgr;, and 7.3-fold for TNF&agr; compared to sham animals. Immunostaining of the lungs of shock animals demonstrated IL-6 protein localized to cells lining the luminal sides of bronchiols. These animals also demonstrated a 2-fold and 5.5-fold increase in activation of NF-&kgr;B and Stat3 (an IL-6 signaling intermediate), respectively. Administration of NOX (30 mg/kg/h beginning at 60 min of shock for total of 4.5 h) resulted in reduced lung injury as measured by a 46% reduction in PMN infiltration, a 20% decrease in wet-to-dry ratio, and improved arterial blood gases. NOX reduced proinflammatory signaling in the lung as demonstrated by a 62% decrease in NF-&kgr;B binding, 47% reduction in Stat3 binding, a reduction in mRNA expression of 48% for IL-6, 57% for ICAM-1, 67% for IL-1&bgr;, and 64% for TNF&agr;, as well as a marked reduction in the intensity of IL-6 protein staining. These data indicate that NOX prevents lung injury in this HS model, possibly through downmodulation of proinflammatory signaling and the shock-induced inflammatory response.

Hemorrhagic shock induces G-CSF expression in bronchial epithelium

Hemorrhagic shock (HS) initiates a series of inflammatory processes that includes the activation of polymorphonuclear granulocytic neutrophils (PMN). We tested the hypothesis that HS induces granulocyte colony-stimulating factor (G-CSF), a cytokine that augments PMN effector functions, in the lungs of rats. Sprague-Dawley rats were subjected to compensated or decompensated HS followed by resuscitation and death at 4 or 8 h. Animals subjected to HS demonstrated acute lung injury with PMN infiltration, edema, and hypoxia. Using semiquantitative reverse transcriptase-polymerase chain reaction, we detected a 1.9- to 7.1-fold increase in G-CSF mRNA levels in the lung of animals subjected to HS compared with sham controls. Levels of G-CSF mRNA increased with increased duration of the ischemic phase of resuscitated shock. In situ hybridization revealed that bronchoepithelial cells were the major cellular site of G-CSF mRNA. Thus production of G-CSF mRNA by bronchoepithelial cells is dramatically increased in a rat model of HS that also demonstrated lung injury. Increased local G-CSF levels may contribute to PMN recruitment and activation and resultant lung injury in HS.Hemorrhagic shock (HS) initiates a series of inflammatory processes that includes the activation of polymorphonuclear granulocytic neutrophils (PMN). We tested the hypothesis that HS induces granulocyte colony-stimulating factor (G-CSF), a cytokine that augments PMN effector functions, in the lungs of rats. Sprague-Dawley rats were subjected to compensated or decompensated HS followed by resuscitation and death at 4 or 8 h. Animals subjected to HS demonstrated acute lung injury with PMN infiltration, edema, and hypoxia. Using semiquantitative reverse transcriptase-polymerase chain reaction, we detected a 1.9- to 7.1-fold increase in G-CSF mRNA levels in the lung of animals subjected to HS compared with sham controls. Levels of G-CSF mRNA increased with increased duration of the ischemic phase of resuscitated shock. In situ hybridization revealed that bronchoepithelial cells were the major cellular site of G-CSF mRNA. Thus production of G-CSF mRNA by bronchoepithelial cells is dramatically increased in a rat model of HS that also demonstrated lung injury. Increased local G-CSF levels may contribute to PMN recruitment and activation and resultant lung injury in HS.