Microbial profiling of combat wound infection through detection microarray and next-generation sequencing.

Combat wound healing and resolution are highly affected by the resident microbial flora. We therefore sought to achieve comprehensive detection of microbial populations in wounds using novel genomic technologies and bioinformatics analyses. We employed a microarray capable of detecting all sequenced pathogens for interrogation of 124 wound samples from extremity injuries in combat-injured U.S. service members. A subset of samples was also processed via next-generation sequencing and metagenomic analysis. Array analysis detected microbial targets in 51% of all wound samples, with Acinetobacter baumannii being the most frequently detected species. Multiple Pseudomonas species were also detected in tissue biopsy specimens. Detection of the Acinetobacter plasmid pRAY correlated significantly with wound failure, while detection of enteric-associated bacteria was associated significantly with successful healing. Whole-genome sequencing revealed broad microbial biodiversity between samples. The total wound bioburden did not associate significantly with wound outcome, although temporal shifts were observed over the course of treatment. Given that standard microbiological methods do not detect the full range of microbes in each wound, these data emphasize the importance of supplementation with molecular techniques for thorough characterization of wound-associated microbes. Future application of genomic protocols for assessing microbial content could allow application of specialized care through early and rapid identification and management of critical patterns in wound bioburden.

Proteomic sample preparation for blast wound characterization.

BACKGROUND: Blast wounds often involve diverse tissue types and require substantial time and treatment for appropriate healing. Some of these subsequent wounds become colonized with bacteria requiring a better understanding of how the host responds to these bacteria and what proteomic factors contribute wound healing outcome. In addition, using reliable and effective proteomic sample preparation procedures can lead to novel biomarkers for improved diagnosis and therapy. RESULTS: To address this need, suitable sample preparation for 2-D DIGE proteomic characterization of wound effluent and serum samples from combat-wounded patients was investigated. Initial evaluation of crude effluent and serum proved the necessity of high abundant protein depletion. Subsequently, both samples were successfully depleted using Agilent Multiple Affinity Removal system and showed greatly improved 2-D spot maps, comprising 1,800 and 1,200 protein spots, respectively. CONCLUSION: High abundant protein removal was necessary for both wound effluent and serum. This is the first study to show a successful method for high abundant protein depletion from wound effluent which is compatible with downstream 2-D DIGE analysis. This development allows for improved biomarker discovery in wound effluent and serum samples.

Osteogenic gene expression correlates with development of heterotopic ossification in war wounds.

BACKGROUND: Heterotopic ossification (HO) is a frequent complication of modern wartime extremity injuries. The biological mechanisms responsible for the development of HO in traumatic wounds remain elusive. QUESTION/PURPOSES: The aims of our study were to (1) characterize the expression profile of osteogenesis-related gene transcripts in traumatic war wounds in which HO developed; and (2) determine whether expression at the mRNA level correlated with functional protein expression and HO formation. METHODS: Biopsy specimens from 54 high-energy penetrating extremity wounds obtained at the initial and final surgical débridements were evaluated. The levels of selected osteogenic-related gene transcripts from RNA extracts were assessed by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. As a result of its key role in osteogenesis, the concentration of BMP-2 in the effluent of 29 wounds also was determined. RESULTS: The transcripts of 13 genes (ALPL [p = 0.006], BMP-2 [p < 0.001], BMP-3 [p = 0.06], COL2A1 [p < 0.001], COLL10A1 [p < 0.001], COL11A1 [p = 0.006], COMP [p = 0.02], CSF2 [p = 0.003], CSF3 [p = 0.012], MMP8 [p < 0.001], MMP9 [p = 0.014], SMAD1 [p = 0.024], and VEGFA [p = 0.017]) were upregulated greater than twofold in wounds in which HO developed compared with wounds in which it did not develop. Gene transcript expression of BMP-2 also correlated directly with functional protein expression in the wounds that formed HO (p = 0.029). CONCLUSIONS: Important differences exist in the osteogenic gene expression profile of wounds in which HO developed compared with wounds in which it did not develop. The upregulation of multiple osteogenesis-related gene transcripts indicates the presence of a proosteogenic environment necessary for ectopic bone formation in traumatic wounds. CLINICAL RELEVANCE: Understanding the osteogenic environment associated with war wounds may allow for the development of novel therapeutic strategies for HO.

Wound outcome in combat injuries is associated with a unique set of protein biomarkers.

BACKGROUND: The ability to forecast whether a wound will heal after closure without further debridement(s), would provide substantial benefits to patients with severe extremity trauma. METHODS: Wound effluent is a readily available material which can be collected without disturbing healthy tissue. For analysis of potential host response biomarkers, forty four serial combat wound effluent samples from 19 patients with either healing or failing traumatic- and other combat-related wounds were examined by 2-D DIGE. Spot map patterns were correlated to eventual wound outcome (healed or wound failure) and analyzed using DeCyder 7.0 and differential proteins identified via LC-MS/MS. RESULTS: This approach identified 52 protein spots that were differentially expressed and thus represent candidate biomarkers for this clinical application. Many of these proteins are intimately involved in inflammatory and immune responses. Furthermore, discriminate analysis further refined the 52 differential protein spots to a smaller subset of which successfully differentiate between wounds that will heal and those that will fail and require further surgical intervention with greater than 83% accuracy. CONCLUSION: These results suggest candidates for a panel of protein biomarkers that may aid traumatic wound care prognosis and treatment. We recommend that this strategy be refined, and then externally validated, in future studies of traumatic wounds.

Bayesian modeling of pretransplant variables accurately predicts kidney graft survival.

INTRODUCTION: Machine learning can enable the development of predictive models that incorporate multiple variables for a systems approach to organ allocation. We explored the principle of Bayesian Belief Network (BBN) to determine whether a predictive model of graft survival can be derived using pretransplant variables. Our hypothesis was that pretransplant donor and recipient variables, when considered together as a network, add incremental value to the classification of graft survival. METHODS: We performed a retrospective analysis of 5,144 randomly selected patients (age ≥18, deceased donor kidney only, first-time recipients) from the United States Renal Data System database between 2000 and 2001. Using this dataset, we developed a machine-learned BBN that functions as a pretransplant organ-matching tool. RESULTS: A network of 48 clinical variables was constructed and externally validated using an additional 2,204 patients of matching demographic characteristics. This model was able to predict graft failure within the first year or within 3 years (sensitivity 40%; specificity 80%; area under the curve, AUC, 0.63). Recipient BMI, gender, race, and donor age were amongst the pretransplant variables with strongest association to outcome. A 10-fold internal cross-validation showed similar results for 1-year (sensitivity 24%; specificity 80%; AUC 0.59) and 3-year (sensitivity 31%; specificity 80%; AUC 0.60) graft failure. CONCLUSION: We found recipient BMI, gender, race, and donor age to be influential predictors of outcome, while wait time and human leukocyte antigen matching were much less associated with outcome. BBN enabled us to examine variables from a large database to develop a robust predictive model.

Metalloproteinase expression is associated with traumatic wound failure.

BACKGROUND: Matrix metalloproteinases (MMPs) are crucial in the inflammatory and remodeling phases of wound healing. We previously reported the correlation between pro-inflammatory cytokines and timing of successful combat-wound closure. We now extend our studies to investigate the correlation between wound-remodeling MMP expression and wound healing. METHODS: Thirty-eight wounds in 25 patients with traumatic extremity combat wounds were prospectively studied. Surgical debridement with vacuum-assisted closure (VAC) device application was repeated every 48 to 72h until surgical wound closure. Wound effluent and patient serum were collected at each wound debridement and analyzed for five matrix metalloproteinases using the Luminex multiplex system; Millipore Corp, Billerica, MA. The primary outcome was wound healing within 30 d of definitive wound closure. Impairment was defined as delayed wound closure (>21 d from injury) or wound dehiscence. MMP expression was compared between impaired and normal healing wounds. RESULTS: Elevated levels of serum MMP-2 and MMP-7 and reduced levels of effluent MMP3 were seen in impaired wounds (n = 9) compared with wounds that healed (n = 29; P<0.001). Receiver operating characteristic (ROC) curve analysis yielded area-under-the-curve (AUC) of 0.744, 0.783, and 0.805, respectively. CONCLUSIONS: Impaired wound healing is characterized by pro-inflammatory MMP-2 and MMP-7. Serum and effluent concentrations of MMP-2, MMP-3, and MMP-7 can effectively predict the outcome of traumatic war wounds and can potentially provide decision-supportive, objective evidence for the timing of wound closure.

Monitoring the healing of combat wounds using Raman spectroscopic mapping.

Soldiers wounded in modern warfare present with extensive and complicated acute wounds, confounded by an overwhelming inflammatory response. The pathophysiology of acute wounds is unknown and timing of wound closure remains subjective. Collagen gene expression profiles are presented for 24 patients. Impaired healing wounds showed a twofold decrease in the up-regulation of COL1A1 and COL3A1 genes in the beginning of the wound healing process, compared with normal healing wounds. By the final debridement, however, collagen gene expression profiles for normal and impaired healing wounds were similar for COL1A1 and COL3A1. In addition, Raman spectroscopic maps were collected of biopsy tissue sections, from the first and last debridements of 10 wounds collected from nine patients. Tissue components obtained for the debridement biopsies were compared to elucidate whether or not a wound healed normally. Raman spectroscopy showed a loss of collagen in five patients, indicated by a negative percent difference in the 1,665/1,445 cm(-1) band area ratios. Four healed patients showed an increased or unchanged collagen content. Here, we demonstrate the potential of Raman spectroscopic analysis of wound biopsies for classification of wounds as normal or impaired healing. Raman spectroscopy has the potential to noninvasively monitor collagen deposition in the wound bed, during surgical wound debridements, to help determine the optimal time for wound closure.

Combat Wound Initiative program.

The Combat Wound Initiative (CWI) program is a collaborative, multidisciplinary, and interservice public-private partnership that provides personalized, state-of-the-art, and complex wound care via targeted clinical and translational research. The CWI uses a bench-to-bedside approach to translational research, including the rapid development of a human extracorporeal shock wave therapy (ESWT) study in complex wounds after establishing the potential efficacy, biologic mechanisms, and safety of this treatment modality in a murine model. Additional clinical trials include the prospective use of clinical data, serum and wound biomarkers, and wound gene expression profiles to predict wound healing/failure and additional clinical patient outcomes following combat-related trauma. These clinical research data are analyzed using machine-based learning algorithms to develop predictive treatment models to guide clinical decision-making. Future CWI directions include additional clinical trials and study centers and the refinement and deployment of our genetically driven, personalized medicine initiative to provide patient-specific care across multiple medical disciplines, with an emphasis on combat casualty care.

Inflammatory biomarkers in combat wound healing.

BACKGROUND: Modern war ballistics and blast injuries inflict devastating extremity injuries, violating soft tissue, bone, and neurovascular structures. Despite advances in complex wound management, appropriate timing of war wound closure remains subjective. In addition, the pathophysiology of acute wound failure is poorly defined. METHODS: Patients with penetrating extremity wounds sustained during combat were prospectively studied and followed for 30 days after definitive wound closure. The primary outcome was wound healing. Wound dehiscence was defined as spontaneous partial or complete wound disruption after closure. Serum, wound effluent, and wound bed tissue biopsy were collected at each surgical wound debridement. Serum and wound effluent were analyzed with a multiplex array of 22 cytokines and chemokines, and wound tissue for corresponding gene transcript expression. RESULTS: Fifty-two penetrating extremity war wounds in 33 male patients were investigated. Nine (17%) wounds dehisced. Concomitant vascular injury, increased wound size, and higher injury severity score correlated with wound dehiscence. Both serum and wound effluent cytokine and chemokine protein profiles were statistically associated with healing outcome at various time points. Wound biopsy gene transcript expression demonstrated increased tissue inflammation associated with wound failure. Multiple protein and gene transcript biomarkers predictive of wound healing were identified. CONCLUSIONS: The cytokine and chemokine protein and gene transcript expression patterns demonstrate a condition of inflammatory dysregulation associated with war wound failure. A molecular biomarker panel may predict combat wound healing outcome and warrants prospective validation.

Perioperative blood transfusion in combat casualties: a pilot study.

BACKGROUND: In recent studies, blood transfusion has been shown to increase the rate of wound healing disturbances in orthopedic patients. Furthermore, our group has determined a correlation between delayed wound healing and elevations in inflammatory mediators in combat casualties. Therefore, we sought to determine the effect of blood transfusion on wound healing and inflammatory mediator release in combat casualties. METHODS: Prospective data were collected on 20 severely injured combat casualties sustaining extremity wounds. Patients were admitted to the National Naval Medical Center during a 13-month period from January 2007 to January 2008. Data variables included age, gender, Glasgow coma score (GCS), mechanism of injury, and transfusion history. Injury severity was assessed using the Injury Severity Score (ISS). Serum was collected initially and before each surgical wound debridement and analyzed using a panel of 21 cytokines and chemokines. The association between blood transfusion and wound healing, incidence of perioperative infection, intensive care unit (ICU) admission rate, and ICU and hospital length of stay was assessed. Differences were considered significant when p < 0.05. RESULTS: The study cohort had a mean age of 22 +/- 1, a mean ISS of 15.8 +/- 2.6, and a mean GCS 13.9 +/- 0.6; all were men and suffered penetrating injuries (90% improvised explosive device [IED] and 10% gunshot wound [GSW]). The cohort was divided into two groups. Patients receiving 4 units of blood initially (group 2, n = 9). There was no significant difference in age, ISS, GCS, or mortality between the two groups. However, group 2 patients had significant impairment in wound healing rate (54% vs. 9%, p < 0.05), higher ICU admission rate (78% vs. 9%, p < 0.01), perioperative infection rate (89% vs. 27%, p < 0.01), and a longer hospital length of stay (49.9 +/- 12.8 vs. 23.8 +/- 2.9, p < 0.05) compared with group 1 patients. In addition, there was a significant correlation between the initial mean serum cytokine/chemokine level of interleukin (IL)-10, IL-8, interferon inducible protein (IP)-10, IL-6, and IL-12p40 and the number of units of blood transfused (p < 0.05). CONCLUSION: Allogeneic blood transfusions in combat casualties were associated with impaired wound healing, increased perioperative infection rate, and resource utilization. In addition, the extent of blood transfusion was associated with significant differences in inflammatory chemokine and cytokine release.

Design of a highly reactive HDV ribozyme sequence uncovers facilitation of RNA folding by alternative pairings and physiological ionic strength.

The hepatitis delta virus (HDV) ribozyme is a self-cleaving RNA that resides in the HDV genome and regulates its replication. The native fold of the ribozyme is complex, having two pseudoknots. Earlier work implicated four non-native pairings in slowing pseudoknot formation: Alt 1, Alt 2, Alt 3, and Alt P1. The goal of the present work was design of a kinetically simplified and maximally reactive construct for in vitro mechanistic and structural studies. The initial approach chosen was site-directed mutagenesis in which known alternative pairings were destabilized while leaving the catalytic core intact. Based on prior studies, the G11C/U27Delta double mutant was prepared. However, biphasic kinetics and antisense oligonucleotide response trends opposite those of the well-studied G11C mutant were observed suggesting that new alternative pairings with multiple registers, termed Alt X and Alt Y, had been created. Enzymatic structure mapping of oligonucleotide models supported this notion. This led to a model wherein Alt 2 and the phylogenetically conserved Alt 3 act as "folding guides", facilitating folding of the major population of the RNA molecules by hindering formation of the Alt X and Alt Y registers. Attempts to eliminate the strongest of the Alt X pairings by rational design of a quadruple mutant only resulted in more complex kinetic behavior. In an effort to simultaneously destabilize multiple alternative pairings, studies were carried out on G11C/U27Delta in the presence of urea or increased monovalent ion concentration. Inclusion of physiological ionic strength allowed the goal of monophasic, fast-folding (kobs approximately 60 min(-1)) kinetics to be realized. To account for this, a model is developed wherein Na+, which destabilizes secondary and tertiary structures in the presence of Mg2+, facilitates native folding by destabilizing the multiple alternative secondary structures with a higher-order dependence.

Serum Inflammatory Cytokine Markers of Invasive Fungal Infection in Previously Immunocompetent Battle Casualties.

BACKGROUND: Invasive fungal infection (IFI) is described increasingly in individuals experiencing high-energy military trauma. Hallmarks of successful treatment involve aggressive surgical debridement and early initiation of systemic antimicrobial therapy. Currently, intravenous anti-fungal therapy commences based on appearance of wounds and patient's clinical course. Whereas some clinical protocols exist to predict which critically injured patients should receive anti-fungal therapies, there are no established serum markers associated with IFI. Our hypothesis is that serum inflammatory cytokines exist that can assist in identifying individuals at risk for IFI. METHODS: This is a retrospective case control study at a single institution. Nine patients with IFI (Saksenaea vasiformis, Fusarium sp., Graphium sp., Scedosporium sp., Aspergillus sp., Mucor sp., and Alternaria sp.) after battlefield trauma were matched to nine individuals with similar injury patterns whose laboratory results were negative for IFI. The combination of serum inflammatory cytokines from the first and second debridements was examined with multiplex platform proteomic analysis. We defined statistical significance as a two-tailed α<0.05 after adjusting for multiple comparisons using the false discovery rate method. This model was refined further with correlation-based filter selection and the area under the curve of the receiver operating characteristics (AUROC) was tested. RESULTS: Both groups had similar Injury Severity Scores (ISS) (mean±standard deviation [SD]) (26.8±15.5 vs. 29.2±16.8, p=0.766). Elevated RANTES (regulated on activation, normal T cell expressed and secreted) alone (10,492.8±4,450.1 vs. 5,333.3±4,162.2, p=0.006) correlated with IFI. Also, the combination of persistent elevations in RANTES, interleukin (IL)-2R, and IL-15 was a robust model for predicting IFI with the AUROC being 0.9. CONCLUSIONS: Elevation in serum cytokines, particularly RANTES, correlated with IFI in this small group of patients. This demonstrates the potential of future rapid serum testing for early initiation and guidance of anti-fungal therapies.

Bilateral lower-extremity amputation wounds are associated with distinct local and systemic cytokine response.

BACKGROUND: Approximately 25% of U.S. military members sustaining extremity amputations in recent military conflicts have bilateral lower-extremity amputations (BLA). We investigated among combat-related extremity wounds whether BLA exhibit different bacterial burden, inflammatory response, and local complications. METHODS: A total of 75 patients with combat-related extremity wounds (19 BLA) were evaluated for age, tobacco use, body mass index, Injury Severity Score, Acute Physiology and Chronic Health Evaluation II, and delayed primary closure time. Blood, wound exudates, and muscle biopsies were obtained and analyzed for cytokine and quantitative bacteriology, excluding patients using nonsteroidal anti-inflammatory medications and corticosteroids, due to potential effects on their inflammatory profile. RESULTS: BLA was not associated with differences in age, tobacco use, body mass index, and delayed primary closure time, but these patients had increased Injury Severity Score, Acute Physiology and Chronic Health Evaluation II, and rates of critical colonization. Proinflammatory cytokines including tumor necrosis factor-α (exudate), interleukin (IL)-1 (exudate) and IL-6 (serum) were increased in BLA patients. They also had serum and exudate increased IL-8 and decreased IL-13 and granulocyte-macrophage colony-stimulating factor. Both wound dehiscence (WD) and heterotopic ossification (HO) were more common in BLA patients. CONCLUSION: BLA patients were more likely to exhibit critical bacterial colonization, a distinct inflammatory response, and develop WD and HO. Modulating this response represents an attractive target in an effort to prevent complications such as WD and HO.

Lymphocyte modulation with FTY720 improves hemorrhagic shock survival in swine.

The inflammatory response to severe traumatic injury results in significant morbidity and mortality. Lymphocytes have recently been identified as critical mediators of the early innate immune response to ischemia-reperfusion injury. Experimental manipulation of lymphocytes following hemorrhagic shock may prevent secondary immunologic injury in surgical and trauma patients. The objective of this study is to evaluate the lymphocyte sequestration agent FTY720 as an immunomodulator following experimental hemorrhagic shock in a swine liver injury model. Yorkshire swine were anesthetized and underwent a grade III liver injury with uncontrolled hemorrhage to induce hemorrhagic shock. Experimental groups were treated with a lymphocyte sequestration agent, FTY720, (n = 9) and compared to a vehicle control group (n = 9). Animals were observed over a 3 day survival period after hemorrhage. Circulating total leukocyte and neutrophil counts were measured. Central lymphocytes were evaluated with mesenteric lymph node and spleen immunohistochemistry (IHC) staining for CD3. Lung tissue infiltrating neutrophils were analyzed with myeloperoxidase (MPO) IHC staining. Relevant immune-related gene expression from liver tissue was quantified using RT-PCR. The overall survival was 22.2% in the vehicle control and 66.7% in the FTY720 groups (p = 0.081), and reperfusion survival (period after hemorrhage) was 25% in the vehicle control and 75% in the FTY720 groups (p = 0.047). CD3(+) lymphocytes were significantly increased in mesenteric lymph nodes and spleen in the FTY720 group compared to vehicle control, indicating central lymphocyte sequestration. Lymphocyte disruption significantly decreased circulating and lung tissue infiltrating neutrophils, and decreased expression of liver immune-related gene expression in the FTY720 treated group. There were no observed infectious or wound healing complications. Lymphocyte sequestration with FTY720 improves survival in experimental hemorrhagic shock using a porcine liver injury model. These results support a novel and clinically relevant lymphocyte immunomodulation strategy to ameliorate secondary immune injury in hemorrhagic shock.

Inflammatory cytokine and chemokine expression is associated with heterotopic ossification in high-energy penetrating war injuries.

OBJECTIVE: Heterotopic ossification (HO) develops frequently after modern high-energy penetrating war injuries. The purpose of this prospective study was to identify and characterize the unique cytokine and chemokine profile associated with the development of HO as it pertained to the systemic inflammatory response after penetrating combat-related trauma. METHODS: Patients with high-energy penetrating extremity wounds were prospectively enrolled. Surgical debridement along with the use of a pulse lavage and vacuum-assisted-closure device was performed every 48-72 hours until definitive wound closure. Wound bed tissue biopsy, wound effluent, and serum were collected before each debridement. Effluent and serum were analyzed for 22 relevant cytokines and chemokines. Tissue was analyzed quantitatively for bacterial colonization. Correlations between specific wound and patient characteristics were also analyzed. The primary clinical outcome measure was the formation of HO as confirmed by radiographs at a minimum of 2 months of follow-up. RESULTS: Thirty-six penetrating extremity war wounds in 24 patients were investigated. The observed rate of HO in the study population was 38%. Of the 36 wounds, 13 (36%) demonstrated HO at a minimum follow-up of 2 months. An elevated injury severity score was associated with the development of HO (P = 0.006). Wound characteristics that correlated with the development of HO included impaired healing (P = 0.005) and bacterial colonization (P < 0.001). Both serum (interleukin-6, interleukin-10, and MCP-1) and wound effluent (IP-10 and MIP-1α) cytokine and chemokine bioprofiles were individually associated and suggestive of the development of HO (P < 0.05). CONCLUSIONS: A severe systemic and wound-specific inflammatory state as evident by elevated levels of inflammatory cytokines, elevated injury severity score, and bacterial wound colonization is associated with the development of HO. These findings suggest that the development of HO in traumatic combat-related wounds is associated with a hyper-inflammatory systemic response to injury. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Lymphocyte depletion in experimental hemorrhagic shock in Swine.

BACKGROUND: Hemorrhagic shock results in systemic activation of the immune system and leads to ischemia-reperfusion injury. Lymphocytes have been identified as critical mediators of the early innate immune response to ischemia-reperfusion injury, and immunomodulation of lymphocytes may prevent secondary immunologic injury in surgical and trauma patients. METHODS: Yorkshire swine were anesthetized and underwent a grade III liver injury with uncontrolled hemorrhage to induce hemorrhagic shock. Experimental groups were treated with a lymphocyte depletional agent, porcine polyclonal anti-thymocyte globulin (PATG) (n = 8) and compared to a vehicle control group (n = 9). Animals were observed over a 3 day survival period. Circulating lymphocytes were examined with FACS analysis for CD3/CD4/CD8, and central lymphocytes with mesenteric lymph node and spleen staining for CD3. Circulating and lung tissue16 infiltrating neutrophils were measured. Circulating CD3 lymphocytes in the blood and in central lymphoid organs (spleen/lymph node) were stained and evaluated using FACS analysis. Immune-related gene expression from liver tissue was quantified using RT-PCR. RESULTS: The overall survival was 22% (2/9) in the control and 75% (6/8) in the PATG groups, p = 0.09; during the reperfusion period (following hemorrhage) survival was 25% (2/8) in the control and 100% (6/6) in the PATG groups, p = 0.008. Mean blood loss and hemodynamic profiles were not significantly different between the experimental and control groups. Circulating CD3+CD4+ lymphocytes were significantly depleted in the PATG group compared to control. Lymphocyte depletion in the setting of hemorrhagic shock also significantly decreased circulating and lung tissue infiltrating neutrophils, and decreased expression of liver ischemia gene expression. CONCLUSIONS: Lymphocyte manipulation with a depletional (PATG) strategy improves reperfusion survival in experimental hemorrhagic shock using a porcine liver injury model. This proof of principle study paves the way for further development of immunomodulation approaches to ameliorate secondary immune injury following hemorrhagic shock.

Inflammatory response is associated with critical colonization in combat wounds.

BACKGROUND: Modern combat- or blast-related injuries are characterized by devastatingly massive zones of injury that violate soft tissue, bone, and neurovascular structures. In our translational research program, we have determined that healing of traumatic combat wounds is dependent on the immune response. Although the majority of combat wounds are not critically colonized with bacteria, there exists a correlation between critical colonization and the concentration of inflammatory cytokines and chemokines measured in wound effluent or patient serum. METHODS: Patients with penetrating extremity wounds sustained during combat operations were studied prospectively, being followed for 30 days after definitive wound closure. Surgical debridement was repeated every 48-72 h until wound closure at the discretion of the attending surgeon. Serum, wound effluent, and wound bed tissue biopsy were collected at each debridement. Serum and wound effluent were analyzed with a multiplex assay for cytokines, chemokines, and inflammatory proteases, whereas wound tissue was assessed for microbial colonization via quantitative cultures. Correlations between serum and effluent cytokines and chemokines and the degree of tissue colonization were evaluated. RESULTS: Samples from 154 debridements in 38 wounds from 25 male patients were investigated. Many of the patients sustained multi-system trauma (mean Injury Severity Score 21±12 points) and were critically ill (mean Acute Physiology and Chronic Health Evaluation II score 7±5 points). Healing failure occurred in 23.7% of wounds. A marked inflammatory profile, including increased serum and wound effluent cytokines and chemokines, was associated with the extent of critical colonization. CONCLUSIONS: The correlation between systemic and local inflammatory cytokines and quantitative culture suggests that the interplay between the systemic response to injury and the local wound environment is a determinant of outcome. This relationship remains ill defined and requires further investigation in both clinical and pre-clinical studies. A biomarker panel reflective of colonization may provide clinically useful, objective criteria indicating when wound closure is appropriate for successful healing.

Biomarker use in tailored combat casualty care.

Modern war wounds are complex and primarily involve extremities. They require multiple operative interventions to achieve wound closure and begin rehabilitation. Current assessment of the suitability of surgical wound closure is based upon subjective methods coupled with a semiquantitative determination of the wound bacterial burden. Measurement of the systemic and local response to injury using inflammatory biomarkers may allow for accelerated wound closure and treatment of other combat-related morbidity. This article presents the introduction of personalized medicine into combat casualty care.

Development of a Bayesian model to estimate health care outcomes in the severely wounded.

BACKGROUND: Graphical probabilistic models have the ability to provide insights as to how clinical factors are conditionally related. These models can be used to help us understand factors influencing health care outcomes and resource utilization, and to estimate morbidity and clinical outcomes in trauma patient populations. STUDY DESIGN: Thirty-two combat casualties with severe extremity injuries enrolled in a prospective observational study were analyzed using step-wise machine-learned Bayesian belief network (BBN) and step-wise logistic regression (LR). Models were evaluated using 10-fold cross-validation to calculate area-under-the-curve (AUC) from receiver operating characteristics (ROC) curves. RESULTS: Our BBN showed important associations between various factors in our data set that could not be developed using standard regression methods. Cross-validated ROC curve analysis showed that our BBN model was a robust representation of our data domain and that LR models trained on these findings were also robust: hospital-acquired infection (AUC: LR, 0.81; BBN, 0.79), intensive care unit length of stay (AUC: LR, 0.97; BBN, 0.81), and wound healing (AUC: LR, 0.91; BBN, 0.72) showed strong AUC. CONCLUSIONS: A BBN model can effectively represent clinical outcomes and biomarkers in patients hospitalized after severe wounding, and is confirmed by 10-fold cross-validation and further confirmed through logistic regression modeling. The method warrants further development and independent validation in other, more diverse patient populations.