Priming, second-hit priming, and apoptosis in leukocytes from trauma patients

Independent predictors of systemic inflammatory response syndrome for intramedullary nailing of femoral shaft fractures: Analysis of national inpatient sample database

Background

The systemic inflammatory response syndrome (SIRS) is a clinical reaction that can occur due to a variety of stimuli. Reamed intramedullary femoral nailing is a common orthopedic surgery that has been shown to induce SIRS. To date, no nationwide analyses have been performed to evaluate the incidence, risk factors, and economic burdens of SIRS following intramedullary femoral nailing for femoral shaft fractures. The objective of this study is to investigate the independent predictors, incidence, post-operative, and economic burden of SIRS among patients treated with intramedullary nailing for femoral shaft fractures.

Methods

We utilized the 2016-2019 National Inpatient Sample (NIS) to identify patients who underwent intramedullary femoral nailing and were diagnosed with non-infectious SIRS (NI-SIRS) based on ICD-10-CM coding. Identified patients who underwent intramedullary femoral nailing were dichotomized into SIRS and Non-SIRS groups to assess independent predictors of SIRS development, and to compare post-operative complications and costs.

Results

A total of 65,240 patients with femur shaft fractures underwent IMFN, of which 665 (1.0 %) developed NI-SIRS. Patients with NI-SIRS had a higher incidence of laparotomy (OR = 13.97, p < 0.001), initial treatment with external fixation (OR = 1.845, p < 0.001), and late application of external fixation (OR = 4.884, p = 0.005). Routine discharge (OR = 0.491, p < 0.001) was less likely in patients with NI-SIRS. Length of stay (12.38 days vs 7.16 days, p < 0.001) and total charges ($278, 590 vs $145,118, p < 0.001) were both increased in patients with NI-SIRS.

Conclusion

NI-SIRS is associated with increasing injury severity and post-operative complications. Those that developed NI-SIRS experienced higher healthcare resource utilization. Risk factors associated with development of NI-SIRS warrant further investigation.

Optimized flow cytometry assays to monitor neutrophil activation in human and mouse whole blood samples

Polymorphonuclear neutrophils (PMNs) protect the host from invading microorganisms. However, excessively activated PMNs can also cause damage to host tissues under inflammatory conditions. Here we developed simple assays to determine the activation state of PMNs in human whole blood that contains soluble mediators known to influence PMN functions. Because mouse models are widely used to study the role of PMNs in infectious and inflammatory diseases, we adapted these assays for the rapid and reliable assessment of PMN functions in murine blood samples. Freshly collected whole blood samples were stimulated with agonists of the formyl peptide receptors (FPR) of PMNs and changes in reactive oxygen species (ROS) production and the expression of CD11b, CD62L (L-selectin), CD66b, and CD63 on the cell surface were analyzed with flow cytometry. We optimized these assays to minimize inadvertent interferences such as cell stress generated during sample handling and the loss of plasma mediators that regulate PMN functions. Human PMNs readily responded to the FPR agonist N-formyl-methionyl-leucyl-phenylalanine (fMLP). The most sensitive responses of human PMNs to fMLP were CD11b, CD62L, and CD66b expression with half maximal effective concentrations (EC₅₀) of 5, 8, and 6 nM fMLP, respectively. CD63 expression and ROS production required markedly higher fMLP concentrations with EC₅₀ values of 19 and 50 nM fMLP, respectively. Mouse PMNs did not respond well to fMLP and required significantly higher concentrations of the FPR agonist WKYMVm (W-peptide) to achieve equivalent cell activation. The most sensitive response of mouse PMNs was ROS production with an EC₅₀ of 38 nM W-peptide. Because mice do not express CD66b, we only assessed the expression of CD62L, CD11b, and CD63 with EC₅₀ values of 54, 119, and 355 nM W-peptide, respectively. Validation of our optimized assays showed that they sensitively detect the responses of human PMNs to priming with endotoxin in vitro as well as the corresponding responses of murine PMNs to bacterial infection in a sepsis model. We conclude that these optimized assays could be useful tools for the monitoring of patients with infections, sepsis, and other inflammatory conditions as well as for the design and interpretation of preclinical studies of these diseases in mouse models.

TREM-1 is required for enhanced OpZ-induced superoxide generation following priming

Inflammatory agents, microbial products, or stromal factors pre-activate or prime neutrophils to respond to activating stimuli in a rapid and aggressive manner. Primed neutrophils exhibit enhanced chemotaxis, phagocytosis, and respiratory burst when stimulated by secondary activating stimuli. We previously reported that Triggering Receptor Expressed on Myeloid cells-1 (TREM-1) mediates neutrophil effector functions such as increased superoxide generation, transepithelial migration, and chemotaxis. However, it is unclear whether TREM-1 is required for the process of priming itself or for primed responses to subsequent stimulation. To investigate this, we utilized in vitro and in vivo differentiated neutrophils that were primed with TNF-α and then stimulated with the particulate agonist, opsonized zymosan (OpZ). Bone marrow progenitors isolated from WT and Trem-1-/- mice were transduced with estrogen regulated Homeobox8 (ER-Hoxb8) fusion transcription factor and differentiated in vitro into neutrophils following estrogen depletion. The resulting neutrophils expressed high levels of TREM-1 and resembled mature in vivo differentiated neutrophils. The effects of priming on phagocytosis and oxidative burst were determined. Phagocytosis did not require TREM-1 and was not altered by priming. In contrast, priming significantly enhanced OpZ-induced oxygen consumption and superoxide production in WT but not Trem-1-/- neutrophils indicating that TREM-1 is required for primed oxidative burst. TREM-1-dependent effects were not mediated during the process of priming itself as priming enhanced degranulation, ICAM-1 shedding, and IL-1ß release to the same extent in WT and Trem-1-/- neutrophils. Thus, TREM-1 plays a critical role in primed phagocytic respiratory burst and mediates its effects following priming.

Gut Microbial Changes and their Contribution to Post-Burn Pathology

ABSTRACT

Burn injuries are a common form of traumatic injury that leads to significant morbidity and mortality worldwide. Burn injuries are characterized by inflammatory processes and alterations in numerous organ systems and functions. Recently, it has become apparent that the gastrointestinal bacterial microbiome is a key component of regulating the immune response and recovery from burn and can also contribute to significant detrimental sequelae after injury, such as sepsis and multiple organ failure. Microbial dysbiosis has been linked to multiple disease states; however, its role in exacerbating acute traumatic injuries, such as burn, is poorly understood. In this article, we review studies that document changes in the intestinal microbiome after burn injury, assess the implications in post-burn pathogenesis, and the potential for further discovery and research.

Novel neutrophil phenotypic signature in pediatric patients with type 1 diabetes and diabetic ketoacidosis

Type 1 diabetes (T1D) is a chronic inflammatory condition sometimes complicated by acute diabetic ketoacidosis (DKA). A subset of patients with T1D develop DKA independent of known risk factors. This study tested the hypothesis that circulating polymorphonuclear leukocytes (PMN) from children with T1D and DKA would exhibit a primed phenotype and that the signature would be unique in patients predisposed to have DKA. Using a prospective cohort study design, neutrophil phenotype was assessed in 30 patients with T1D seen in endocrinology clinic for routine care, 30 patients with acute DKA, and 36 healthy donors. Circulating PMN from patients with DKA display a primed phenotype with increased basal cell-surface CD11b, L-selectin shedding, and enhanced fMLF-elicited reactive oxygen species (ROS) production. Moreover, PMN from T1D patients both with and without DKA lack the capacity to be further primed by incubation with TNF-α, a classic priming stimulus. Primed PMN phenotypic signatures demonstrated are independent of hemoglobin A1c, the premier biological marker for DKA risk, and are consistent with a hyperinflammatory state. A single nucleotide polymorphism in TLR-1 (1805G>T), known to be associated with a hyperinflammatory PMN phenotype, correlated with DKA. This study elucidated a novel phenotypic signature in circulating PMN from children with T1D with and without DKA, and suggests the possibility of a previously unrecognized PMN phenotype with potential clinical implications. Immunophenotype and genotype may be applicable as biomarkers for DKA risk stratification in patients with T1D.

Splenectomy is associated with altered leukocyte kinetics after severe trauma

BACKGROUND

Inadequate activation of the innate immune system after trauma can lead to severe complications such as Acute Respiratory Distress Syndrome and Multiple Organ Dysfunction Syndrome. The spleen is thought to modulate the cellular immune system. Furthermore, splenectomy is associated with improved outcome in severely injured trauma patients. We hypothesized that a splenectomy alters the cellular immune response in polytrauma.

METHODS

All adult patients with an ISS ≥ 16 and suffering from splenic or hepatic injuries were selected from our prospective trauma database. Absolute leukocyte numbers in peripheral blood were measured. White blood cell kinetics during the first 14 days were compared between splenectomized patients, patients treated surgically for liver trauma and nonoperatively treated individuals.

RESULTS

A total of 129 patients with a mean ISS of 29 were included. Admission characteristics and leukocyte numbers were similar in all groups, except for slightly impaired hemodynamic status in patients with operatively treated liver injuries. On admission, leukocytosis occurred in all groups. During the first 24 h, leukopenia developed gradually, although significantly faster in the operatively treated patients. Thereafter, leukocyte levels normalized in all nonoperatively treated cases whereas leukocytosis persisted in operatively treated patients. This effect was significantly more prominent in splenectomized patients than all other conditions.

CONCLUSIONS

This study demonstrates that surgery for intra-abdominal injuries is associated with an early drop in leucocyte numbers in peripheral blood. Moreover, splenectomy in severely injured patients is associated with an altered cellular immune response reflected by a persistent state of prominent leukocytosis after trauma.

Late Mortality Prediction of Neutrophil-to-lymphocyte and Platelet Ratio in Patients With Trauma Who Underwent Emergency Surgery: A Retrospective Study

BACKGROUND

We aimed to evaluate the usefulness of neutrophil-to-lymphocyte (N/L) and neutrophil-to-lymphocyte platelet (N/LP) ratios in predicting late mortality of patients with trauma who underwent emergency surgery.

MATERIALS AND METHODS

We retrospectively evaluated patients with trauma older than 19 y who underwent emergency surgery at our level I trauma center. Blood count-based ratios (N/L and N/LP at days 1, 3, and 7 of hospitalization) and trauma scores were analyzed. Statistical analysis was performed using univariable logistic regression and receiver operating curves.

RESULTS

A total of 209 patients were evaluated. N/LP at day 7, N/L at day 7, Trauma Injury Severity Score, Revised Trauma Score, and Injury Severity Score were significantly associated with late mortality. Area under the receiver operating characteristic curves for predicting mortality was highest for N/LP at day 7 (0.867 [95% confidence interval 0.798-0.936], P < 0.001). The group with N/LP greater than the cutoff value (9.3, sensitivity 77.3%, specificity 83.1%) at day 7 showed higher mortality than the group with N/LP less than the cutoff value (35.4% versus 3.2%, P < 0.001, respectively) at day 7.

CONCLUSIONS

N/LP at day 7 may be a superior predictor of late mortality compared with preexisting trauma scores in patients with major trauma undergoing emergency surgery, by better reflecting the systemic inflammation status.

Developmental ablation of mature oligodendrocytes exacerbates adult CNS demyelination

Multiple sclerosis (MS) is a CNS neurodegenerative autoimmune disease characterized by loss of oligodendrocytes and myelin in the brain and the spinal cord that results in localized functional deficits. Several risk factors have been associated with MS, however none fully explain the enhanced susceptibility seen in older individuals. Epidemiological data, based on geographical prevalence studies suggest that susceptibility is established early in life and frequently long before the diagnosis of disease raising the possibility that developmental events influence adult disease onset and progression. Here we test the hypothesis that selective loss of mature oligodendrocytes during postnatal development results in enhanced susceptibility to a demyelinating insult to the mature CNS. A transgenic mouse model was utilized to specifically induce apoptotic cell death in a subset of mature oligodendrocytes (MBP-iCP9) during the first 2 postnatal weeks followed by either a local LPC spinal cord injection or the induction of EAE in the adult animal. Immunostaining, immunoblotting, behavioral testing, and electron microscopy were utilized to examine the differences in the response between animals with developmental loss of oligodendrocytes and controls. We show that during development, oligodendrocyte apoptosis results in transient reductions in myelination and functional deficits that recover after 10–14 days. Compared to animals in which oligodendrocyte development was unperturbed, animals subjected to postnatal oligodendrocyte loss showed delayed recovery from an LPC lesion to the mature spinal cord. Unexpectedly, the induction and severity of MOG induced EAE was not significantly altered in animals following oligodendrocyte developmental loss even though there was a substantial increase in spinal cord tissue damage and CNS inflammation. It is unclear why the elevated glial responses seen in developmentally compromised animals were not reflected in enhanced functional deficits. These observations suggest that developmental loss of oligodendrocytes results in long lasting tissue changes that alter its response to subsequent insults and the capacity for repair in the adult.

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Developmental oligodendrocyte apoptosis induces transient myelin and functional loss.

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Developmental loss of oligodendrocytes compromises adult remyelination after LPC.

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Developmental loss of oligodendrocytes enhances CNS immune response in EAE.

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Elevated CNS glial reactivity does not alter course of EAE.

Damage control orthopedics applied in an 8-year-old child with life-threatening multiple injuries: A CARE-compliant case report

RATIONALE

Damage control is a staged surgical approach to manage polytraumatized patients. The damage control approach comprises three steps. First, bleeding is controlled and fractures are stabilized temporarily; second, vital parameters are stabilized and the child is rewarmed in the intensive care unit; and third, the child is reoperated for definitive repair of injuries. We aimed to describe the feasibility of the damage control orthopedic approach in a child.

PATIENT CONCERNS

An 8-year-old girl fell from the balcony of the 5th floor onto concrete pavement and was admitted to our accident and emergency ward in a stable cardiorespiratory state, but with gross deformity of the lower limbs, left thigh, and forearm.

DIAGNOSES

The child had sustained multiple injuries with severe bilateral lung contusion, pneumothorax, fracture of first rib, liver laceration, stable spine fractures, transforaminal fracture of sacrum, pelvic ring fracture, displaced baso-cervical femoral neck fracture, displaced bilateral multifragmental growth plate fractures of both tibiae, fractures of both fibulae, displaced fracture of left forearm, and displaced supracondylar fracture of the humerus.

INTERVENTION

In the initial operation, we performed closed reduction and K-wire fixation of the right tibia, closed reduction and external fixation of the left tibia, open reduction and screw osteosynthesis of the femoral neck fracture, closed reduction and K-wire fixation of the radius, and closed reduction of the supracondylar fracture. Subsequently, we transferred the girl to the pediatric intensive care unit for hemodynamic stabilization, respiratory therapy, rewarming, and treatment of crush syndrome. In a third step, 10 days after the injury, we managed the supracondylar fracture of the humerus by closed reduction and K-wire fixation.

OUTCOMES

Growth arrest of the left distal tibial growth plate and osteonecrosis of the femoral head and neck, slipped capital femoris epiphysis (SCFE), and coxa vara of the right femur led to balanced leg length inequality 2 years after the injury. The lesion of the left sciatic nerve improved over time and the girl walked without walking aids and took part in school sports but avoided jumping exercises.

LESSONS

We emphasize the importance of damage control principles when managing polytraumatized children.

Osteoimmunology: Effects of Standard Orthopaedic Interventions on Inflammatory Response and Early Fracture Healing

Achieving fracture union is highly dependent on the initial inflammatory phase of fracture healing, which is influenced by both the local and systemic inflammatory environments. The rapidly emerging field of osteoimmunology involves the study of the interactions between the immune system and the skeletal system. Recent research has advanced the current state of knowledge regarding the effects of the surrounding soft-tissue injury, fracture hematoma, and the method of fracture fixation on the inflammatory phase of fracture healing. Acute systemic inflammation, as seen in patients with polytrauma, and chronic systemic inflammation, as seen in patients with diabetes or rheumatoid arthritis, affects the inflammatory phase of fracture healing. The use of NSAIDs can influence early fracture healing. Understanding the effects of standard orthopaedic interventions on the local and systemic inflammatory responses and early fracture healing is important for optimizing fracture union.

Neutrophil Phenotype Correlates With Postoperative Inflammatory Outcomes in Infants Undergoing Cardiopulmonary Bypass

OBJECTIVES

Infants with congenital heart disease frequently require cardiopulmonary bypass, which causes systemic inflammation. The goal of this study was to determine if neutrophil phenotype and activation status predicts the development of inflammatory complications following cardiopulmonary bypass.

DESIGN

Prospective cohort study.

SETTING

Tertiary care PICU with postoperative cardiac care.

PATIENTS

Thirty-seven patients 5 days to 10 months old with congenital heart disease requiring cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Laboratory and clinical data collected included length of mechanical ventilation, acute kidney injury, and fluid overload. Neutrophils were isolated from whole blood at three time points surrounding cardiopulmonary bypass. Functional analyses included measurement of cell surface protein expression and nicotinamide adenine dinucleotide phosphate oxidase activity. Of all patients studied, 40.5% displayed priming of nicotinamide adenine dinucleotide phosphate oxidase activity in response to N-formyl-Met-Leu-Phe stimulation 24 hours post cardiopulmonary bypass as compared to pre bypass. Neonates who received steroids prior to bypass demonstrated enhanced priming of nicotinamide adenine dinucleotide phosphate oxidase activity at 48 hours. Patients who displayed priming post cardiopulmonary bypass were 8.8 times more likely to develop severe acute kidney injury as compared to nonprimers. Up-regulation of neutrophil surface CD11b levels pre- to postbypass occurred in 51.4% of patients, but this measure of neutrophil priming was not associated with acute kidney injury. Subsequent analyses of the basal neutrophil phenotype revealed that those with higher basal CD11b expression were significantly less likely to develop acute kidney injury.

CONCLUSIONS

Neutrophil priming occurs in a subset of infants undergoing cardiopulmonary bypass. Acute kidney injury was more frequent in those patients who displayed priming of nicotinamide adenine dinucleotide phosphate oxidase activity after cardiopulmonary bypass. This pilot study suggests that neutrophil phenotypic signature could be used to predict inflammatory organ dysfunction.

Endocytosis is required for exocytosis and priming of respiratory burst activity in human neutrophils

OBJECTIVE AND DESIGN

Neutrophil generation of reactive oxygen species (ROS) is enhanced by exposure to pro-inflammatory agents in a process termed priming. Priming is depending on exocytosis of neutrophil granules and p47^phox phosphorylation-dependent translocation of cytosolic NADPH oxidase components. Clathrin-mediated endocytosis was recently reported to be necessary for priming, but the mechanism linking endocytosis to priming was not identified. The present study examined the hypothesis that endocytosis regulates neutrophil priming by controlling granule exocytosis.

MATERIALS AND METHODS

Clathrin-mediated endocytosis by isolated human neutrophils was inhibited by chlorpromazine, monodansylcadaverine, and sucrose. Exocytosis of granule subsets was measured as release of granule components by ELISA or chemiluminescence. ROS generation was measured as extracellular release of superoxide as reduction of ferrocytochrome c. p38 MAPK activation and p47^phox phosphorylation were measured by immunoblot analysis. Statistical analysis was performed using a one-way ANOVA with the Tukey-Kramer multiple-comparison test.

RESULTS

Inhibition of endocytosis prevented priming of superoxide release by TNFα and inhibited TNFα stimulation and priming of exocytosis of all four granule subsets. Inhibition of endocytosis did not reduce TNFα-stimulated p38 MAPK activation or p47^phox phosphorylation. Inhibition of NADPH oxidase activity blocked TNFα stimulation of secretory vesicle and gelatinase granule exocytosis.

CONCLUSIONS

Endocytosis is linked to priming of respiratory burst activity through ROS-mediated control of granule exocytosis.

Multiple Phenotypic Changes Define Neutrophil Priming

Exposure to pro-inflammatory cytokines, chemokines, mitochondrial contents, and bacterial and viral products induces neutrophils to transition from a basal state into a primed one, which is currently defined as an enhanced response to activating stimuli. Although, typically associated with enhanced generation of reactive oxygen species (ROS) by the NADPH oxidase, primed neutrophils show enhanced responsiveness of exocytosis, NET formation, and chemotaxis. Phenotypic changes associated with priming also include activation of a subset of functions, including adhesion, transcription, metabolism, and rate of apoptosis. This review summarizes the breadth of phenotypic changes associated with priming and reviews current knowledge of the molecular mechanisms behind those changes. We conclude that the current definition of priming is too restrictive. Priming represents a combination of enhanced responsiveness and activated functions that regulate both adaptive and innate immune responses.

BLOCKADE OF ENDOTHELIAL GROWTH FACTOR, ANGIOPOIETIN-2, REDUCES INDICES OF ARDS AND MORTALITY IN MICE RESULTING FROM THE DUAL-INSULTS OF HEMORRHAGIC SHOCK AND SEPSIS

We have demonstrated hemorrhagic shock "priming" for the development of indirect acute respiratory distress syndrome (iARDS) in mice following subsequent septic challenge, and show pathology characteristic of patients with iARDS, including increased lung microvascular permeability and arterial PO2/FI02 reduced to levels comparable to mild/moderate ARDS during the 48 h following hemorrhage. Loss of endothelial cell (EC) barrier function is a major component in the development of iARDS. EC growth factors, Angiopoietin (Ang)-1 and 2, maintain vascular homeostasis via tightly regulated competitive interaction with tyrosine kinase receptor, Tie2, expressed on ECs. Ang-2/Tie2 binding, in contrast to Ang-1, is believed to produce vessel destabilization, pulmonary leakage, and inflammation. Recent clinical findings from our trauma/surgical intensive care units and others have reported elevated Ang-2 in the plasma from patients that develop ARDS. We have previously described similarly elevated Ang-2 in plasma and lung tissue in our shock/sepsis model for the development of iARDS, and demonstrated effective reduction in indices of inflammation and lung tissue injury following siRNA inhibition of Ang-2 protein synthesis. In this study we show that Ang-2 in lung tissue and plasma spikes following hemorrhage (priming) and remain elevated at sepsis induction. In addition, that transient inhibition of Ang-2 function immediately following hemorrhage, suppressing priming, but not following sepsis, impacts the development of iARDS in our model. Our data demonstrate that selective temporal blockade of Ang-2 function following hemorrhagic shock priming significantly improved PO2/FIO2, decreased lung protein leak and indices of inflammation, and improved 10-day survival in our murine model for the development iARDS.

Neutrophil azurophilic granule exocytosis is primed by TNF-α and partially regulated by NADPH oxidase

Neutrophil (polymorphonuclear leukocyte) activation with release of granule contents plays an important role in the pathogenesis of acute lung injury, prompting clinical trials of inhibitors of neutrophil elastase. Despite mounting evidence for neutrophil-mediated host tissue damage in a variety of disease processes, mechanisms regulating azurophilic granule exocytosis at the plasma membrane, and thus release of elastase and other proteases, are poorly characterized. We hypothesized that azurophilic granule exocytosis would be enhanced under priming conditions similar to those seen during acute inflammatory events and during chronic inflammatory disease, and selected the cytokine TNF-α to model this in vitro. Neutrophils stimulated with TNF-α alone elicited intracellular reactive oxygen species (ROS) generation and mobilization of secretory vesicles, specific, and gelatinase granules. p38 and ERK1/2 MAPK were involved in these components of priming. TNF-α priming alone did not mobilize azurophilic granules to the cell surface, but did markedly increase elastase release into the extracellular space in response to secondary stimulation with N-formyl-Met-Leu-Phe (fMLF). Priming of fMLF-stimulated elastase release was further augmented in the absence of NADPH oxidase-derived ROS. Our findings provide a mechanism for host tissue damage during neutrophil-mediated inflammation and suggest a novel anti-inflammatory role for the NADPH oxidase.

Compartment syndrome causes systemic inflammation in a rat

Aims

Compartment syndrome results from increased intra-compartmental pressure (ICP) causing local tissue ischaemia and cell death, but the systemic effects are not well described. We hypothesised that compartment syndrome would have a profound effect not only on the affected limb, but also on remote organs.

Methods

Using a rat model of compartment syndrome, its systemic effects on the viability of hepatocytes and on inflammation and circulation were directly visualised using intravital video microscopy.

Results

We found that hepatocellular injury was significantly higher in the compartment syndrome group (192 PI-labelled cells/10-1 mm3, standard error of the mean (sem) 51) compared with controls (30 PI-labelled cells/10-1 mm3, sem 12, p < 0.01). The number of adherent venular white blood cells was significantly higher for the compartment syndrome group (5 leukocytes/30s/10 000 μm2, sem 1) than controls (0.2 leukocytes/30 s/10 000 μm2, sem 0.2, p < 0.01). Volumetric blood flow was not significantly different between the two groups, although there was an increase in the heterogeneity of perfusion.

Conclusions

Compartment syndrome can be accompanied by severe systemic inflammation and end organ damage. This study provides evidence of the relationship between compartment syndrome in a limb and systemic inflammation and dysfunction in a remote organ. Cite this article: Bone Joint J 2016; 98-B:1132–7.

Enhanced expression of aquaporin 9 in activated polymorphonuclear leukocytes in patients with systemic inflammatory response syndrome

Aquaporins (AQPs) are water channels of cell membranes. All living cells experience osmotic pressure changes in their environment, but the mechanism by which water influx occurs was not known until the discovery of AQPs. AQP9, which is expressed in human polymorphonuclear leukocytes (PMNLs), is reported to relate to morphologic changes of PMNLs in vitro. We examined the expression of AQP9 in PMNLs from patients with systemic inflammatory response syndrome (SIRS) and addressed the role of AQP9 in both morphologic and functional changes of PMNLs in the SIRS condition. Fourteen patients with SIRS were included in our study. Polyclonal antibody was used for the AQP9 assay. F-actin polymerization, oxidative activity, and the expression of AQP9 in PMNLs with and without stimulation by N-formylmethionyl-leucyl-phenylalanine were evaluated by flow cytometry. Expression of AQP9, F-actin polymerization, and oxidative activity in PMNLs were increased significantly in patients with SIRS compared with those in healthy volunteers. The time course of AQP9 fluorescence in PMNLs corresponded to the time course of F-actin polymerization, which showed peak fluorescence at 1 min after N-formylmethionyl-leucyl-phenylalanine stimulation. The expression of AQP9 in PMNLs is increased significantly in SIRS patients. The increased expression of AQP9 in SIRS patients might be associated with F-actin polymerization in PMNLs, which could affect both morphologic and functional changes of PMNLs in the SIRS condition.

Major postoperative complications following elective resection for colorectal cancer decrease long-term survival but not the time to recurrence

AIM

The aim of the study was to determine the effect of major complications after colorectal cancer surgery on survival and time to recurrence.

METHOD

Patients having a curative colorectal cancer resection and a follow-up of at least 3 years were identified from a prospective database. Major complications were defined as Clavien-Dindo Grades 3b or 4 and their impact on time to recurrence and mortality was analysed by univariate and multivariable analysis. Postoperative death within 30 days or during the initial hospitalization (Clavien-Dindo Grade 5) was a priori excluded.

RESULTS

From 2003 to 2012, 868 colorectal cancer resections resulting in 63 (7%) major postoperative complications including deaths (Clavien-Dindo ≥ 3b) were identified. After exclusion of Grade 5 complications (postoperative or in-hospital deaths), 844 resections with 39 (5%) major complications remained for analysis. Median follow-up time was 5.7 years. Using the Kaplan-Meier method, the estimated crude 5-year overall survival probability was 78% (95% CI 75-81) in the group without and 65% (95% CI 51-83) in the group with major complications (P = 0.009, log-rank test). Major complications were a significant negative predictor for overall survival (hazard ratio 2.42, 95% CI 1.41-4.14) when adjusted for sex, age, American Society of Anesthesiologists grade, tumour site (colon vs rectum), R stage and tumour stage. However, in both univariate and multivariable analysis, major complications were not a significant predictor for time to recurrence (hazard ratio 1.29, 95% CI 0.56-2.99).

CONCLUSION

Non-lethal major postoperative complications seem to have a negative long-term impact on survival but not on time to recurrence.

Pulmonary preconditioning, injury, and inflammation modulate expression of the candidate tumor suppressor gene ECRG4 in lung

PURPOSE

The human c2orf40 gene encodes a candidate tumor suppressor called Esophageal Cancer-Related Gene-4 (ECRG4) that is a cytokine-like epigenetically-regulated protein that is characteristically downregulated in cancer, injury, inflammation, and infection. Here, we asked whether ECRG4 gene expression is detectable in lung epithelial cells and if its expression changes with inflammation, infection, and/or protective preconditioning.

MATERIALS AND METHODS

We used immunoblotting, PCR, and quantitative PCR to measure ECRG4 and either inhalation anesthesia preconditioning, lipopolysaccharide injection, or laparotomy to modulate lung inflammation.

RESULTS

Immunoblotting establishes the presence of the full-length 14 kDa ECRG4 peptide in mouse lung. Immunohistochemistry localizes ECRG4 to type l alveolar epithelial cells. Basal ECRG4 mRNA is greater than TNF-α, IL-1β, and IL-6 but following inflammatory lung injury, TNF-α, IL-1β, IL-6, and IL-10 are upregulated while ECRG4 gene expression is decreased. Similar findings are observed after an intravenous administration of lipopolysaccharide. In contrast, lung preconditioning with isoflurane anesthesia increases lung ECRG4 gene expression. Over-expression of ECRG4 in human lung epithelial cells in vitro decreases cell proliferation implying that a loss of ECRG4 in vivo would be permissive to cell growth.

CONCLUSIONS

This study supports the hypothesis that ECRG4 acts as a sentinel growth inhibitor in lung alveolar epithelial cells. Its downregulation by injury, infection, and inflammation and upregulation by preconditioning supports a role for ECRG4 in regulating the alveolar epithelium response to injury and inflammation. By extension, the findings support a functional consequence to its inhibition by promoter hypermethylation (i.e. lung cancer) and suggest potential benefits to its upregulation.

Uncontrolled sepsis: a systematic review of translational immunology studies in intensive care medicine

BACKGROUND

The design of clinical immunology studies in sepsis presents several fundamental challenges to improving the translational understanding of pathologic mechanisms. We undertook a systematic review of bed-to-benchside studies to test the hypothesis that variable clinical design methodologies used to investigate immunologic function in sepsis contribute to apparently conflicting laboratory data, and identify potential alternatives that overcome various obstacles to improve experimental design.

METHODS

We performed a systematic review of the design methodology employed to study neutrophil function (respiratory burst), monocyte endotoxin tolerance and lymphocyte apoptosis in the intensive care setting, over the past 15 years. We specifically focussed on how control samples were defined, taking into account age, gender, ethnicity, concomitant therapies, timing of sample collection and the criteria used to diagnose sepsis.

RESULTS

We identified 57 eligible studies, the majority of which (74%) used case-control methodology. Healthy volunteers represented the control population selected in 83% of studies. Comprehensive demographic data on age, gender and ethnicity were provided in ≤48% of case control studies. Documentation of diseases associated with immunosuppression, malignancy and immunomodulatory therapies was rare. Less than half (44%) of studies undertook independent adjudication for the diagnosis of sepsis while 68% provided microbiological data. The timing of sample collection was defined by highly variable clinical criteria. By contrast, surgical studies avoided many such confounders, although only one study in surgical patients monitored the study group for development of sepsis.

CONCLUSIONS

We found several important and common limitations in the clinical design of translational immunologic studies in human sepsis. Major elective surgery overcame many of these methodological limitations. The failure of adequate clinical design in mechanistic studies may contribute to the lack of translational therapeutic progress in intensive care medicine.

Immune response to traumatic injury: harmony and discordance of immune system homeostasis

Trauma remains one of the leading causes of death worldwide. Traumatic injury disrupts immune system homeostasis and may predispose patients to opportunistic infections and inflammatory complications. Prevention of multiple organ dysfunction syndrome due to septic complications following severe trauma is a challenging problem. Following severe injury, the immune system usually tends toward a pro-inflammatory phenotype and then changes to a counter-inflammatory phenotype. This immune system homeostasis is believed to be a protective response based on the balance between the innate and adaptive immune systems. We reported that injury activates inflammasomes and primes Toll-like receptors. The primed innate immune system is prepared for a rapid and strong antimicrobial immune defense. However, trauma can also develop the "two-hit" response phenotype. We also reported that injury augments regulatory T cell activity, which can control the "two-hit" response phenotype in trauma. We discuss the current idea that traumatic injury induces a unique type of innate and adaptive immune response that may be triggered by damage-associated molecular pattern molecules, which are a combination of endogenous danger signal molecules that include alarmins and pathogen-associated molecular pattern molecules.

Neutrophils from critically ill septic patients mediate profound loss of endothelial barrier integrity

Introduction

Sepsis is characterized by systemic immune activation and neutrophil-mediated endothelial barrier integrity compromise, contributing to end-organ dysfunction. Studies evaluating endothelial barrier dysfunction induced by neutrophils from septic patients are lacking, despite its clinical significance. We hypothesized that septic neutrophils would cause characteristic patterns of endothelial barrier dysfunction, distinct from experimental stimulation of normal neutrophils, and that treatment with the immunomodulatory drug β-glucan would attenuate this effect.

Methods

Blood was obtained from critically ill septic patients. Patients were either general surgery patients (Primary Sepsis (PS)) or those with sepsis following trauma (Secondary Sepsis (SS)). Those with acute respiratory distress syndrome (ARDS) were identified. Healthy volunteers served as controls. Neutrophils were purified and aliquots were untreated, or treated with fMLP or β-glucan. Endothelial cells were grown to confluence and activated with tissue necrosis factor (TNF)-α . Electric Cell-substrate Impedance Sensing (ECIS) was used to determine monolayer resistance after neutrophils were added. Groups were analyzed by two-way analysis of variance (ANOVA).

Results

Neutrophils from all septic patients, as well as fMLP-normal neutrophils, reduced endothelial barrier integrity to a greater extent than untreated normal neutrophils (normalized resistance of cells from septic patients at 30 mins = 0.90 ± 0.04; at 60 mins = 0.73 ± 0.6 and at 180 mins = 0.56 ± 0.05; p < 0.05 vs normal). Compared to untreated PS neutrophils, fMLP-treated PS neutrophils caused further loss of barrier function at all time points; no additive effect was noted in stimulation of SS neutrophils beyond 30 min. Neutrophils from ARDS patients caused greater loss of barrier integrity than those from non-ARDS patients, despite similarities in age, sex, septic source, and neutrophil count. Neutrophils obtained after resolution of sepsis caused less barrier dysfunction at all time points. β-glucan treatment of septic patients’ neutrophils attenuated barrier compromise, rendering the effect similar to that induced by neutrophils obtained once sepsis had resolved.

Conclusions

Neutrophils from septic patients exert dramatic compromise of endothelial barrier integrity. This pattern is mimicked by experimental activation of healthy neutrophils. The effect of septic neutrophils on the endothelium depends upon the initial inflammatory event, correlates with organ dysfunction and resolution of sepsis, and is ameliorated by β-glucan.

Infections after trauma are associated with subsequent cardiac injury

BACKGROUND

Trauma produces profound inflammatory and immune responses. A second hit such as an infection further disrupts the inflammatory cascade. Inflammatory responses, following traumatic injuries, infections, or both, are emerging as biologic mediators of cardiac disease including myocardial ischemia and infarction. Inflammation-induced and stress-related cardiac damage are increasingly recognized in patients with critical illness. It is believed that cardiac dysfunction is the result of alterations in the inflammatory and immune cascades. Urinary tract infections (UTIs) and ventilator-associated pneumonia (VAP) are associated with increased mortality in trauma patients. UTIs and VAPs induced inflammatory responses. We postulate that increased mortality seen in trauma patients with infections is caused by increased rates of cardiac injury.

METHODS

This is a retrospective review of prospectively collected data. All trauma patients admitted to the intensive care unit at our Level I trauma center during 5 years were included in the analysis. Proportional hazard regression analysis was performed to predict suspicion of cardiac injury (troponin ordered), any cardiac injury (troponin > 0.15 ng/mL), or severe cardiac injury (troponin > 1 ng/mL) using age, sex, Injury Severity Score (ISS), pulmonary disease (chronic obstructive pulmonary disease), heart failure, hypertension, diabetes, and the presence of a UTI or VAP. A similar proportion hazard regression was performed to predict mortality.

RESULTS

In the model to predict any cardiac injury, chronic obstructive pulmonary disease (hazards ratio [HR], 1.9; p = 0.02), ISS (HR, 1.01; p = 0.04), VAP (HR, 5.6; p < 0.01), and UTI (HR, 2.4; p = 0.03) were significant. Neither VAP nor UTI predicted severe cardiac injury. In the model to predict death, any cardiac injury was not associated with mortality, but severe cardiac injury and UTI were associated with mortality as age increased.

CONCLUSION

Infectious complications have been associated with increased mortality in trauma patients. Our data demonstrate that development of VAP or UTI is associated with an increased risk of developing cardiac injury in trauma patients, which may contribute to subsequent increased mortality.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.

The role and source of tumor necrosis factor-α in hemorrhage-induced priming for septic lung injury

Tumor necrosis factor α (TNF-α) has been reported to be a key component of the functional priming, of both myeloid and nonmyeloid cells, that is thought to contribute to the lung's increased susceptibility to injury following shock. Not surprisingly, we found that mice deficient in TNF-α exhibited reduced acute lung injury (ALI) resultant from the combined insults of hemorrhagic shock and sepsis. However, we found that when we adoptively transferred neutrophils from mice expressing TNF-α to neutrophil-depleted mice that lacked TNF-α, they were not able to serve as priming stimulus for the development of ALI. Based on these findings, we proposed that resident lung tissue cells mediate TNF-α priming. To begin to unravel the complex signaling pathway of various resident lung tissue cells in TNF-α-induced priming, we compared the effect of local (intratracheal [i.t.]) versus systemic [intravenous (i.v.)] delivery of TNF-α small interference (siRNA). We hypothesized that alternately suppressing expression of TNF-α in lung endothelial (i.v.) or epithelial (i.t.) cells would produce a differential effect in shock-induced ALI. We found that when in vivo siRNA i.t. or i.v. against TNF-α was administered to C57/BL6 mice at 2 h after hemorrhage, 24 h before septic challenge, that systemic/i.v., but not i.t., delivery of TNF-α siRNA following hemorrhage priming significantly reduces expression of indices of ALI compared with controls. These findings suggest that an absence of local lung tissue TNF-α significantly reduces lung tissue injury following hemorrhage priming for ALI and that pulmonary endothelial and/or other possible vascular resident cells, not epithelial cells, play a greater role in mediating the TNF-α priming response in a mouse model of hemorrhage/sepsis-induced ALI.

Endotoxin priming of neutrophils requires endocytosis and NADPH oxidase-dependent endosomal reactive oxygen species

NADPH oxidase 2 (Nox2)-generated reactive oxygen species (ROS) are critical for neutrophil (polymorphonuclear leukocyte (PMN)) microbicidal function. Nox2 also plays a role in intracellular signaling, but the site of oxidase assembly is unknown. It has been proposed to occur on secondary granules. We previously demonstrated that intracellular NADPH oxidase-derived ROS production is required for endotoxin priming. We hypothesized that endotoxin drives Nox2 assembly on endosomes. Endotoxin induced ROS generation within an endosomal compartment as quantified by flow cytometry (dihydrorhodamine 123 and Oxyburst Green). Inhibition of endocytosis by the dynamin-II inhibitor Dynasore blocked endocytosis of dextran, intracellular generation of ROS, and priming of PMN by endotoxin. Confocal microscopy demonstrated a ROS-containing endosomal compartment that co-labeled with gp91(phox), p40(phox), p67(phox), and Rab5, but not with the secondary granule marker CD66b. To further characterize this compartment, PMNs were fractionated by nitrogen cavitation and differential centrifugation, followed by free flow electrophoresis. Specific subfractions made superoxide in the presence of NADPH by cell-free assay (cytochrome c). Subfraction content of membrane and cytosolic subunits of Nox2 correlated with ROS production. Following priming, there was a shift in the light membrane subfractions where ROS production was highest. CD66b was not mobilized from the secondary granule compartment. These data demonstrate a novel, nonphagosomal intracellular site for Nox2 assembly. This compartment is endocytic in origin and is required for PMN priming by endotoxin.

Human spinal cord injury causes specific increases in surface expression of β integrins on leukocytes

Spinal cord injury (SCI) activates circulating leukocytes that migrate into the injured cord and bystander organs using adhesion molecule-mediated mechanisms. These cells cause oxidative damage, resulting in secondary injury to the spinal cord, as well as injury to bystander organs. This study was designed to examine, over a 6-h to 2-week period, changes in adhesion molecule surface expression on human peripheral leukocytes after SCI (9 subjects), using as controls 10 uninjured subjects and 6 general trauma patients (trauma controls, TC). Both the percentage of cells expressing a given adhesion molecule and the average level of its expression was quantified for both circulating neutrophils and monocytes. The percentage of neutrophils and monocytes expressing the selectin CD62L was unchanged in TC and SCI patients after injury compared to uninjured subjects. Concurrently, the amount of surface CD62L on neutrophils was decreased in SCI and TC subjects, and on monocytes after SCI. The percentage of neutrophils expressing α4 decreased in TC, but not in SCI, subjects. Likewise, the percentage of neutrophils and monocytes expressing CD11d decreased markedly in TC subjects, but not after SCI. In contrast, the mean surface expression of α4 and CD11d by neutrophils and monocytes increased after SCI compared with uninjured and TC subjects. The percentage of cells and surface expression of CD11b were similar in neutrophils of all three groups, whereas CD11b surface expression increased after SCI in monocytes. In summary, unlike changes found after general trauma, the proinflammatory stimulation induced by SCI increases the surface expression of adhesion molecules on circulating neutrophils and monocytes before they infiltrate the injured spinal cord and multiple organs of patients. Integrins may be excellent targets for anti-inflammatory treatment after human SCI.

Assessment of hepatic inflammation after spinal cord injury using intravital microscopy

OBJECTIVES

The liver has been shown to play a particularly important role in the initiation and progression of the early systemic inflammatory response (SIR) to spinal cord injury (SCI). The purpose of this study was to determine the time course of leucocyte recruitment to the liver, and to determine the effect of injury severity on the magnitude of leucocyte recruitment and hepatic injury.

METHODS

Rats were randomly assigned to one of the following groups: uninjured, sham-injured (laminectomy and no cord injury), cord compressed or cord transected. At 30 min and 90 min after SCI rats had the left lobe of their livers externalised and visualised using intravital video microscopy.

RESULTS

Thirty minutes after injury the total number of leucocytes per post-sinusoidal venule was significantly increased after cord transection compared to that in uninjured and sham-injured rats (P<0.05). Of these leucocytes, significantly more were adherent to venule walls (P<0.05). At 90 min the total number of leucocytes per post-sinusoidal venule and the number of adherent and rolling leucocytes was significantly increased after cord transection and cord compression (P<0.05).

DISCUSSION

This is the first study to use intravital microscopy to visualise systemic inflammation in the liver following SCI. We have demonstrated immediate leucocyte recruitment to the liver within 30 min after injury and have shown that systemic inflammation increases with time after injury and with severity of injury.

[Comparison of early total care (ETC) and damage control orthopedics (DCO) in the treatment of multiple trauma with femoral shaft fractures: benefit and costs]

INTRODUCTION

Femoral fractures are common injuries in multiple trauma patients. The treatment concept of damage control orthopedics (DCO) is in competition with the concept of early total care (ETC).

PATIENTS AND METHODS

In a retrospective study (2003-2007) 73 multiple trauma patients with femoral shaft fractures were included. The cohort was subdivided according to the Injury Severity Score (ISS) (16-24, 25-39 and more than 40) and treatment strategy (ETC versus DCO). Patients were analyzed for outcome and cost aspects.

RESULTS

In the patient group with an ISS 16-24 ventilation time and intensive care treatment were longer after DCO treatment, overall costs and deficient cost cover were higher in the DCO group. In the patient group with an ISS 25-39 cost aspects showed a higher cover deficient in the DCO group.

CONCLUSION

From an economic point of view the cost deficits for the ETC group were lower than in the DCO group. The treatment strategy should be selected by the pattern of injuries. The costs should be addressed by the Institute for the Hospital Remuneration System (INEK).

Mcl-1-mediated impairment of the intrinsic apoptosis pathway in circulating neutrophils from critically ill patients can be overcome by Fas stimulation

The systemic inflammatory response syndrome and subsequent organ failure are mainly driven by activated neutrophils with prolonged life span, which is believed to be due to apoptosis resistance. However, detailed underlying mechanisms leading to neutrophil apoptosis resistance are largely unknown, and possible therapeutic options to overcome this resistance do not exist. Here we report that activated neutrophils from severely injured patients exhibit cell death resistance due to impaired activation of the intrinsic apoptosis pathway, as evidenced by limited staurosporine-induced mitochondrial membrane depolarization and decreased caspase-9 activity. Moreover, we found that these neutrophils express high levels of antiapoptotic Mcl-1 and low levels of proapoptotic Bax protein. Mcl-1 up-regulation was dependent on elevated concentrations of GM-CSF in patient serum. Accordingly, increased Mcl-1 protein stability and GM-CSF serum concentrations were shown to correlate with staurosporine-induced apoptosis resistance. However, cross-linking of neutrophil Fas by immobilized agonistic anti-Fas IgM resulted in caspase-dependent mitochondrial membrane depolarization and apoptosis induction. In conclusion, the observed impairment of the intrinsic pathway and the resulting apoptosis resistance may be overcome by immobilized agonistic anti-Fas IgM. Targeting of neutrophil Fas by immobilized agonistic effector molecules may represent a new therapeutic tool to limit neutrophil hyperactivation and its sequelae in patients with severe immune disorders.

Pathophysiology of the systemic inflammatory response after major accidental trauma

Background

The purpose of the present study was to describe the pathophysiology of the systemic inflammatory response after major trauma and the timing of final reconstructive surgery.

Methods

An unsystematic review of the medical literature was performed and articles pertaining to the inflammatory response to trauma were obtained. The literature selected was based on the preference and clinical expertise of authors.

Discussion

The inflammatory response consists of hormonal metabolic and immunological components and the extent correlates with the magnitude of the tissue injury. After trauma and uncomplicated surgery a delicate balance between pro- and anti-inflammatory mediators is observed. Trauma patients are, however, often exposed, not only to the trauma, but to several events in the form of initial surgery and later final reconstructive surgery. In this case immune paralysis associated with increased risk of infection might develop. The inflammatory response is normalized 3 weeks following trauma. It has been proposed that the final reconstructive surgery should be postponed until the inflammatory response is normalized. This statement is however not based on clinical trials.

Conclusion

Postponement of final reconstructive surgery until the inflammatory is normalized should be based on prospective randomized trials.

Acute Lung Injury:Apoptosis and Signaling Mechanisms

Acute lung injury (ALI) has been documented clinically following several pathological states such as trauma, septic shock and pneumonia. The histopathological characteristics, paired with the production of a number of cellular pro-inflammatory mediators, play a crucial role in the progression of ALI. During ALI, polymorphonuclear neutrophil (PMN)-mediated apoptosis is delayed by macrophages, possibly via effects on the Fas/FasL mediated pathway, leading to the accumulation of these cells at the site of injury and inflammation. The transcriptional regulation of NFκB, CREB, and AP-1 also regulates the pathogenesis of ALI. During sepsis and septic shock, we found evidence of infiltrating leukocytes in the alveolar spaces along with an increased number of TUNEL-positive cells in the lung sections. We also observed an increased expression of TRADD and Bax/Bcl2 ratio at 7 days post-sepsis. In contrast, the NFκB/IκB ratio increased at 1 day post-sepsis. Together, these data provide evidence illustrating the induction of apoptosis in lung tissues subsequent to the onset of polymicrobial sepsis. The results support the concept that the upregulation of apoptosis following lung inflammation plays a crucial role in the development of acute lung injury and related disorders such as ARDS.

The systemic inflammatory response after spinal cord injury damages lungs and kidneys

Spinal cord injury (SCI) triggers a well characterized, acute, local inflammation leading to secondary damage at the lesion site. Another little recognized problem may be the activation of circulating inflammatory cells that potentially damage tissues outside the cord. We investigated this problem using severe clip-compression SCI in rats. We studied systemic inflammation after SCI and its effects on lungs and kidneys, as dysfunction of these organs is a frequent, early complication after SCI. From 2-24 h after SCI, the number of circulating neutrophils (especially immature cells) significantly increased by 3-10 fold. Flow cytometry experiments revealed that SCI transiently activates these neutrophils, causing increased oxidative responses to phorbolmyristic acid at 2 h after SCI; then, from 4-24 h, the neutrophils were less responsive. Neutrophil longevity was increased (30-50% decrease in apoptosis) at 2-8 h after SCI. Immunohistochemical analyses demonstrated the invasion of neutrophils into lungs and kidneys (2 h-7 d after SCI) and more phagocytic macrophages in lungs (12 h, 3 d after SCI). Myeloperoxidase and matrix metalloproteinase-9 activity in lung and kidney homogenates increased (12 h-7 d after SCI). Expression of COX-2 increased and lipid peroxidation also occurred within this time. Control experiments inducing local cord damage by excitotoxic quisqualate injection verified that SCI per se is sufficient to trigger systemic inflammation and organ damage. In summary, SCI mobilizes and activates neutrophils that then migrate into visceral organs, a phenomenon occurring in parallel with their well-known entry into the cord injury site. The systemic inflammatory response to SCI should be targeted in the development of new therapeutic strategies to treat SCI.

Stimulation of the local femoral inflammatory response to fracture and intramedullary reaming

We have undertaken a prospective study in patients with a fracture of the femoral shaft requiring intramedullary nailing to test the hypothesis that the femoral canal could be a potential source of the second hit phenomenon. We determined the local femoral intramedullary and peripheral release of interleukin-6 (IL-6) after fracture and subsequent intramedullary reaming.

In all patients, the fracture caused a significant increase in the local femoral concentrations of IL-6 compared to a femoral control group. The concentration of IL-6 in the local femoral environment was significantly higher than in the patients own matched blood samples from their peripheral circulation. The magnitude of the local femoral release of IL-6 after femoral fracture was independent of the injury severity score and whether the fracture was closed or open.

In patients who underwent intramedullary reaming of the femoral canal a further significant local release of IL-6 was demonstrated, providing evidence that intramedullary reaming can cause a significant local inflammatory reaction.

SIRS-associated coagulopathy and organ dysfunction in critically ill patients with thrombocytopenia

BACKGROUND

Coagulopathy and thrombocytopenia often occur in critically ill patients, and disseminated intravascular coagulation (DIC) can lead to multiple organ dysfunction and a poor outcome. However, the relation between coagulopathy and systemic inflammatory response has not been thoroughly clarified. Thus, we evaluated coagulative activity, organ dysfunction, and systemic inflammatory response syndrome (SIRS) in critically ill patients with thrombocytopenia and examined the balance between coagulopathy and systemic inflammation.

PATIENTS AND METHODS

Two hundred seventy-three patients, who were admitted to 13 critical care centers in Japan and fulfilled the criteria of platelet count of less than 150*10(9)/L, were included. Coagulative variables (platelet count, fibrin/fibrinogen degradation products, and DIC scores), organ dysfunction index (Sequential Organ Failure Assessment [SOFA] score), and SIRS score in each patient were evaluated for 4 consecutive days after fulfilling the above entry criteria. The effect of SIRS on coagulopathy and organ dysfunction was evaluated in these patients.

RESULTS

Both the maximum SIRS score and entry SIRS score had significant relation to the maximum SOFA score during the observation period. Coagulation disorders indicated by the minimum platelet count, maximum DIC scores, and positivity for DIC worsened gradually with increases in SIRS scores. Both the minimum platelet count and maximum DIC scores were significantly correlated with the maximum SOFA score, indicating that a relation exists between coagulopathy and organ dysfunction.

CONCLUSIONS

In critically ill patients with thrombocytopenia, coagulopathy and organ dysfunction progress with significant mutual correlation, depending on the increase in SIRS scores. The SIRS-associated coagulopathy may play a critical role in inducing organ dysfunction after severe insult.

Endotoxin priming of neutrophils requires NADPH oxidase-generated oxidants and is regulated by the anion transporter ClC-3

Several soluble mediators, including endotoxin, prime neutrophils for an enhanced respiratory burst in response to subsequent stimulation. Priming of neutrophils occurs in vitro, and primed neutrophils are found in vivo. We previously localized the anion transporter ClC-3 to polymorphonuclear leukocytes (PMN) secretory vesicles and demonstrated that it is required for normal NADPH oxidase activation in response to both particulate and soluble stimuli. We now explore the contribution of the NADPH oxidase and ClC-3 to endotoxin-mediated priming. Lipooligosaccharide (LOS) from Neisseria meningitidis enhances the respiratory burst in response to formyl-Met-Leu-Phe, an effect that was impaired in PMNs lacking functional ClC-3 and under anaerobic conditions. Mobilization of receptors to the cell surface and phosphorylation of p38 MAPK by LOS were both impaired in PMN with the NADPH oxidase chemically inhibited or genetically absent and in cells lacking functional ClC-3. Furthermore, inhibition of the NADPH oxidase or ClC-3 in otherwise unstimulated cells elicited a phenotype similar to that seen after endotoxin priming, suggesting that basal oxidant production helps to maintain cellular quiescence. In summary, NADPH oxidase activation was required for LOS-mediated priming, but basal oxidants kept unstimulated cells from becoming primed. ClC-3 contributes to both of these processes.

Screening for Blunt Cerebrovascular Injuries: The Essential Role of Computed Tomography Angiography

The implementation of aggressive diagnostics refuted the thesis that blunt cerebrovascular injuries (BCVI) are rare events. Given the estimates from recent studies, the prevalence may be as high as 1 per 100 among blunt multiple trauma patients. The morbidity and mortality of unrecognized and untreated BCVI is exceptionally high and warrants distinct efforts to detect these injuries during the primary trauma survey. The primary goal is to detect BCVI before neurological symptoms occur, and to introduce anticoagulation or antiplatelet therapy as appropriate. Index injuries such as cervical spine fractures increase the prior probability of disease, but are not helpful in ruling BCVI out. Computed tomography angiography (CTA) may represent the screening tool of choice, although there is still limited evidence about its accuracy. Pooled data from six studies (1368 patients) published between 2002 and 2006 suggest a sensitivity of 79% and a specificity of 97% in the trauma setting. In the two largest investigations, no false negative results were observed. Further research is needed to determine the efficacy of CTA for disclosing BCVI, and to evaluate the potential benefits to patients.

Hypertonic Saline Resuscitation: Efficacy May Require Early Treatment in Severely Injured Patients

BACKGROUND

Activation of polymorphonuclear neutrophils (PMN) is a critical event leading to host tissue injury and organ damage after trauma. Hypertonic saline (HS) resuscitation prevents PMN activation in vitro and in animal models. Here, we studied how clinical parameters and timing requirements influence the efficacy of HS in suppressing PMN activation.

MATERIALS AND METHODS

Twenty-six injured patients and 16 healthy volunteers were included as study subjects. To study how clinical parameters affect the efficacy of HS, whole blood samples from patients were collected 24 hours after admission, treated with HS and N-formyl-methionyl-leucyl-phenylalanine (fMLP), and PMN oxidative burst and degranulation were measured using flow cytometry. We studied the effect of timing on the ability of HS to inhibit PMN function by exposing blood of healthy volunteers to plasma samples from trauma patients before or after the addition of fMLP and HS.

RESULTS

Age and gender did not significantly influence the effect of HS on PMN function. The suppressive effect of clinically relevant HS concentrations (20 mmol/L) on PMN oxidative burst correlated weakly with Sepsis Severity Score (SSS) and Acute Physiology and Chronic Health Evaluation II (APACHE II) score but not with the Injury Severity Score (ISS) or Multiple Organ Failure score (MOF). There was no correlation between any of these clinical scores and degranulation. HS was significantly less effective in suppressing oxidative burst of PMN from patients with ISS >10, APACHE II >5, MOF >0, or SSS >1 compared with patients with ISS < or =10, APACHE II < or =5, MOF = 0, or SSS < or =1. HS more effectively suppressed PMN activation when PMN were pretreatment with HS, whereas it was less effective on PMN previously primed in vivo or in vitro by adding trauma plasma. HS was ineffective on PMN previously stimulated in vitro with fMLP.

CONCLUSIONS

Our data suggest that HS resuscitation may prevent PMN activation most effectively when patients are treated with HS early in the field.

The open abdomen in trauma: do infectious complications affect primary abdominal closure?

OBJECTIVE

One of the primary goals of damage control surgery in the trauma patient is primary closure of the abdomen. We hypothesized that extra-abdominal infections, such as those complicating injuries to the thorax, diaphragm, long bones, or musculoskeletal system, would decrease the likelihood of primary abdominal closure and increase hospital resource utilization in patients requiring open abdominal management.

METHODS

The trauma registry of the American College of Surgeons (TRACS) was reviewed retrospectively from 1995-2002 for open abdomen technique and damage control surgery. The outcome was primary fascial closure or delayed closure. Patients who died prior to closure were excluded. We evaluated infectious complications, including ventilator-associated pneumonia (VAP), blood stream infection (BSI), and surgical site infection (SSI). Other parameters studied were multiple rib fractures, long bone fractures, chest injuries, diaphragm injuries, empyema, and transfusion requirements. Hospital charges were obtained from the hospital administrative database. Univariate, multivariate, and regression analyses were performed to identify the effects of infectious complications on primary abdominal closure, length of stay, total hospital charges, and disposition.

RESULTS

Three hundred forty-four patients required the open abdomen technique: 67% received damage control laparotomy and 33% decompression of abdominal compartment syndrome. Two hundred seventy-six patients (80%) went on to abdominal closure of some form and constituted the primary study group. Primary abdominal closure was achieved in 180 (65%) with a mean time to closure of 3.5 days. Ventilator-associated pneumonia, BSI, and SSI were associated with lack of primary closure (p < 0.05). Increased blood transfusions also were associated with failure of primary closure (p < 0.05). Ventilator-associated pneumonia and BSI were associated with significantly greater lengths of stay in the intensive care unit (ICU) (24.2 days vs. 12.6 days and 30.5 days vs. 17.9 days; both p < 0.0001) and significantly greater total hospital charges (232,080 US dollar vs. 142,893 US dollar; 247,440 US dollar vs. 160,940 US dollar; and 264,778 US dollar vs. 170,447 US dollar; all p < 0.001).

CONCLUSION

Inability to achieve primary abdominal closure was associated with infectious complications (VAP, BSI, and SSI) and large transfusion requirements. Infectious complications also significantly increased ICU utilization and hospital charges. Death was associated with BSI, femur fractures, and large transfusion requirements, whereas infectious complications did not have a significant impact on discharge disposition.

Aberrant regulation of polymorphonuclear phagocyte responsiveness in multitrauma patients

A systemic inflammatory response often follows severe trauma. Priming (preactivation) of polymorphonuclear phagocytes (PMNs) is an essential first step in the processes that lead to damage caused by the systemic activation of innate immune response. Until recently, priming could only accurately be measured by functional assays, which require isolation of cells, thereby potentially inducing artificial activation. The aim of this study was to identify primed PMNs in response to trauma by using a whole blood analysis with a broad detection range. Twenty-two trauma patients were analyzed for PMN priming with novel developed antibodies recognizing priming epitopes by flow cytometric analysis. Expression of priming epitopes on PMNs was analyzed with respect to time, injury, and disease severity. Expression of priming epitopes in the circulation was compared with expression profiles of PMNs obtained from lung fluid. Fourteen healthy volunteers served as controls. Expression of priming epitopes on peripheral blood PMNs of injured patients was similar, as found in healthy controls, whereas highly primed cells were found in the lung fluid of injured patients (increase of >50 times as compared with peripheral blood cells). In fact, the responsiveness of PMNs toward the bacteria-derived stimulus N-formyl-methionyl-leucyl-phenylalanine was markedly decreased in trauma patients. Lack of expression of priming epitopes and the unresponsiveness to N-formyl-methionyl-leucyl-phenylalanine demonstrates the presence of partially refractory cells in the circulation of trauma patients. An increased expression of epitopes found on pulmonary PMNs suggests that optimal (pre)activation of these cells only occurs in the tissues.

Can we safely restrict transfusion in trauma patients?

PURPOSE OF REVIEW

Transfusion of red blood cells in the trauma patient can be lifesaving. The question is how much and when? It is important to weigh the risks and benefits of red blood cell transfusions, as well alternatives to transfusion as these products are not benign.

RECENT FINDINGS

We explore the evidence, and provide the rationale for current and future red blood cell transfusion strategies within a framework of prehospital and hospital care of the trauma patient. We also describe how red blood cell transfusion trends are changing in trauma, discuss alternatives to red blood cell transfusion and present evidence from randomized controlled trials that support a lower transfusion trigger.

SUMMARY

Optimal transfusion practice and use of alternatives in trauma is a rapidly expanding and important area of research. Strong clinical evidence derived by future randomized controlled trials in the area of transfusion triggers as well as transfusion alternatives is required to determine their roles in clinical practice.

The effect of continuous veno-venous hemofiltration or direct hemoperfusion with polymyxin B-immobilized fiber on neutrophil respiratory oxidative burst in patients with sepsis and septic shock

Neutrophil activates and injures tissues and organs during sepsis or septic shock. Blood purification therapies such as continuous veno-venous hemofiltration (CVVH) and direct hemoperfusion with polymyxin-immobilized fiber (PMX-DHP) have been used for the treatment of sepsis and septic shock, however, the effects of such therapies on neutrophil activation have previously been poorly understood. We sought to evaluate neutrophil reactive oxygen species (ROS), especially H2O2 production, in the pathophysiology of sepsis or septic shock and the effect of CVVH or PMX-DHP on neutrophil ROS. Seven critically ill septic patients requiring CVVH (and 12 matched septic patients who did not require CVVH as control) and seven septic shock patients treated with PMX-DHP were studied. We found that patients with sepsis or septic shock had significantly higher levels of neutrophil ROS compared with normal volunteers (183 +/- 42, 292 +/- 90, and 103 +/- 30) (P < 0.05, and < 0.005). Neutrophil ROS did not change over time in patients treated either with CVVH or without CVVH. In contrast, neutrophil ROS significantly inhibited PMX-DHP treatment in patients with septic shock (pretreatment; 292 +/- 88 vs. post-treatment; 205 +/- 93, P < 0.05). In conclusion, neutrophil ROS was significantly enhanced in the sepsis or septic shock affected patients. CVVH did not affect neutrophil ROS while PMX-DHP significant inhibited neutrophil ROS.

Divergent roles of murine neutrophil chemokines in hemorrhage induced priming for acute lung injury

Neutrophil associated lung injury is identified with a variety of local and systemic priming insults. In vitro studies have shown that TNF-alpha mediated suppression of neutrophil apoptosis is due to the secretion of interleukin-8 (IL-8), a human chemokine shown to alter neutrophil chemotaxis. Our initial in vitro antibody neutralization studies with neutrophil chemotactic proteins, keratinocyte-derived chemokine (KC) and macrophage inflammatory protein-2alpha (MIP-2alpha), mouse IL-8 homologues, indicate that MIP-2alpha but not KC appears to mediate TNF-alpha suppression of mouse neutrophil apoptosis. Therefore, we hypothesized that in vivo neutralization of KC or MIP-2alpha during an initial priming insult would produce differential effects on the extent of lung injury by restoring normal neutrophil apoptotic function. To assess this, mice were hemorrhaged followed with septic challenge at 24 h. Antibody against KC or MIP-2alpha or a nonspecific IgG was given during resuscitation immediately following hemorrhage. Anti-MIP-2alpha treatment resulted in a significant reduction in lung tissue IL-6 and myeloperoxidase levels. Percentage of neutrophil apoptosis increased significantly in the anti-KC group. Tissue and plasma KC and MIP-2alpha were reduced in their respective treatment groups. These data suggest that KC and MIP-2alpha differ in their mediation of neutrophil function (apoptosis and chemotaxis) and contribution to the pathogenesis of lung injury following hemorrhage subsequent to sepsis.

The full-length cDNA of anticoagulant protein infestin revealed a novel releasable Kazal domain, a neutrophil elastase inhibitor lacking anticoagulant activity

Infestins are Kazal-type serine proteinase inhibitors found in the midgut of the Chagas' disease vector, Triatoma infestans. In previous studies, we characterized two double-headed infestins with potent anticoagulant activity; infestin 1-2, which inhibits thrombin and infestin 3-4, a factor XIIa inhibitor. In the present work, we have cloned the full-length cDNA of infestins' precursor. The translated cDNA predicted a polypeptide containing a signal peptide and seven Kazal-type domains, four domains from infestin 1-2 and infestin 3-4, and three new domains. Northern blot analysis confirmed that infestins are synthesized in a single transcript (approximately 1,800 bp) in the insect midgut, but not in salivary glands. Based on the cDNA sequence, the three new Kazal domains were named infestin 1R, 2R and 3R. Infestin 2R-3R has 77% amino acid sequence identity to infestin 1-2 and the same basic amino acid residue at P1 position in the inhibitory reactive site suggesting that these two proteins have a similar inhibitory specificity. In contrast, infestin 1R has two different characteristics when compared to the other infestins: i) a hydrophobic amino acid residue at P1 position in the inhibitory reactive site and ii) a prediction to be processed as a single Kazal domain. These two characteristics were experimentally demonstrated by the purification of native infestin 1R from T. infestans midgut. Native infestin 1R was shown to be processed as a single Kazal domain by mass spectrometry and it was able to inhibit neutrophil elastase, subtilisin A and chymotrypsin. To further characterize infestin 1R inhibitory activity, it was expressed as a recombinant protein in bacteria. Recombinant infestin 1R inhibited neutrophil elastase with the same K(i) of the native inhibitor. Moreover, it inhibited subtilisin A, chymotrypsin and proteinase K but did inhibit neither thrombin nor coagulation assays. In conclusion, unlike the other described infestins, infestin 1R did not present anticoagulant activity and is processed as a single Kazal domain with inhibitory specificity towards proteases that hydrolyze peptide bonds after hydrophobic amino acid residues.

Trauma: the role of the innate immune system

Immune dysfunction can provoke (multiple) organ failure in severely injured patients. This dysfunction manifests in two forms, which follow a biphasic pattern. During the first phase, in addition to the injury by trauma, organ damage is caused by the immune system during a systemic inflammatory response. During the second phase the patient is more susceptible for sepsis due to host defence failure (immune paralysis). The pathophysiological model outlined in this review encompasses etiological factors and the contribution of the innate immune system in the end organ damage. The etiological factors can be divided into intrinsic (genetic predisposition and physiological status) and extrinsic components (type of injury or "traumaload" and surgery or "intervention load"). Of all the factors, the intervention load is the only one which, can be altered by the attending emergency physician. Adjustment of the therapeutic approach and choice of the most appropriate treatment strategy can minimize the damage caused by the immune response and prevent the development of immunological paralysis. This review provides a pathophysiological basis for the damage control concept, in which a staged approach of surgery and post-traumatic immunomonitoring have become important aspects of the treatment protocol. The innate immune system is the main objective of immunomonitoring as it has the most prominent role in organ failure after trauma. Polymorphonuclear phagocytes and monocytes are the main effector-cells of the innate immune system in the processes that lead to organ failure. These cells are controlled by cytokines, chemokines, complement factors and specific tissue signals. The contribution of tissue barrier integrity and its interaction with the innate immune system is further evaluated.

SMALL-VOLUME FLUID RESUSCITATION WITH HYPERTONIC SALINE PREVENTS INFLAMMATION BUT NOT MORTALITY IN A RAT MODEL OF HEMORRHAGIC SHOCK

Hemorrhage remains a primary cause of death in civilian and military trauma. Permissive hypotensive resuscitation is a possible approach to reduce bleeding in patients until they can be stabilized in an appropriate hospital setting. Small-volume resuscitation with hypertonic saline (HS) is of particular interest because it allows one to modulate the inflammatory response to hemorrhage and trauma. Here, we tested the utility of permissive hypotensive resuscitation with hypertonic fluids in a rat model of hemorrhagic shock. Animals were subjected to massive hemorrhage [mean arterial pressure (MAP) = 30 - 35 mmHg for 2 h until decompensation] and partially resuscitated with a bolus dose of 4 mL/kg of 7.5% NaCl (HS), hypertonic hydroxyl ethyl starch (HHES; hydroxyl ethyl starch + 7.5% NaCl), or normal saline (NS) followed by additional infusion of Ringer solution to maintain MAP at 40 to 45 mmHg for 40 min (hypotensive state). Finally, animals were fully resuscitated with Ringer solution and the heparinized shed blood. Hypotensive resuscitation with NS caused a significant increase in plasma interleukin (IL)-1beta, IL-6, IL-2, interferon gamma (IFNgamma), IL-10, and granulocyte-macrophage colony stimulating factor (GM-CSF). This increase was blocked by treatment with HS. HHES treatment significantly reduced the increase of IL-1beta and IL-2 but not that of the other cytokines studied. Despite the strong effects of HS and HHES on cytokine production, both treatments had little effect on plasma lactate, base excess (BE), white blood cell (WBC) count, myeloperoxidase (MPO) content, and the wet/dry weight ratio of the lungs. Moreover, on day 7 after shock, the survival rate in rats treated with HS was markedly, but not significantly, lower than that of NS-treated animals (47% vs. 63%, respectively). In summary, hypotensive resuscitation with hypertonic fluids reduces the inflammatory response but not lung tissue damage or mortality after severe hemorrhagic shock.