Nicole S. Gibran

Genomic responses in mouse models poorly mimic human inflammatory diseases

A cornerstone of modern biomedical research is the use of mouse models to explore basic pathophysiological mechanisms, evaluate new therapeutic approaches, and make go or no-go decisions to carry new drug candidates forward into clinical trials. Systematic studies evaluating how well murine models mimic human inflammatory diseases are nonexistent. Here, we show that, although acute inflammatory stresses from different etiologies result in highly similar genomic responses in humans, the responses in corresponding mouse models correlate poorly with the human conditions and also, one another. Among genes changed significantly in humans, the murine orthologs are close to random in matching their human counterparts (e.g., R2 between 0.0 and 0.1). In addition to improvements in the current animal model systems, our study supports higher priority for translational medical research to focus on the more complex human conditions rather than relying on mouse models to study human inflammatory diseases.

A genomic storm in critically injured humans

Critical injury in humans induces a genomic storm with simultaneous changes in expression of innate and adaptive immunity genes.

Cytomegalovirus Reactivation in Critically-Ill Immunocompetent Patients

CONTEXT Cytomegalovirus (CMV) infection is associated with adverse clinical outcomes in immunosuppressed persons, but the incidence and association of CMV reactivation with adverse outcomes in critically ill persons lacking evidence of immunosuppression have not been well defined. OBJECTIVE To determine the association of CMV reactivation with intensive care unit (ICU) and hospital length of stay in critically ill immunocompetent persons. DESIGN, SETTING, AND PARTICIPANTS We prospectively assessed CMV plasma DNAemia by thrice-weekly real-time polymerase chain reaction (PCR) and clinical outcomes in a cohort of 120 CMV-seropositive, immunocompetent adults admitted to 1 of 6 ICUs at 2 separate hospitals at a large US tertiary care academic medical center between 2004 and 2006. Clinical measurements were assessed by personnel blinded to CMV PCR results. Risk factors for CMV reactivation and association with hospital and ICU length of stay were assessed by multivariable logistic regression and proportional odds models. MAIN OUTCOME MEASURES Association of CMV reactivation with prolonged hospital length of stay or death. RESULTS The primary composite end point of continued hospitalization (n = 35) or death (n = 10) by 30 days occurred in 45 (35%) of the 120 patients. Cytomegalovirus viremia at any level occurred in 33% (39/120; 95% confidence interval [CI], 24%-41%) at a median of 12 days (range, 3-57 days) and CMV viremia greater than 1000 copies/mL occurred in 20% (24/120; 95% CI, 13%-28%) at a median of 26 days (range, 9-56 days). By logistic regression, CMV infection at any level (adjusted odds ratio [OR], 4.3; 95% CI, 1.6-11.9; P = .005) and at greater than 1000 copies/mL (adjusted OR, 13.9; 95% CI, 3.2-60; P < .001) and the average CMV area under the curve (AUC) in log(10) copies per milliliter (adjusted OR, 2.1; 95% CI, 1.3-3.2; P < .001) were independently associated with hospitalization or death by 30 days. In multivariable partial proportional odds models, both CMV 7-day moving average (OR, 5.1; 95% CI, 2.9-9.1; P < .001) and CMV AUC (OR, 3.2; 95% CI, 2.1-4.7; P < .001) were independently associated with a hospital length of stay of at least 14 days. CONCLUSIONS These preliminary findings suggest that reactivation of CMV occurs frequently in critically ill immunocompetent patients and is associated with prolonged hospitalization or death. A controlled trial of CMV prophylaxis in this setting is warranted.

Mesenchymal stem cells: paracrine signaling and differentiation during cutaneous wound repair

Cutaneous wounds persist as a health care crisis in spite of increased understanding of the cellular and molecular responses to injury. Contributing significantly to this crisis is the lack of reliable therapies for treatment of wounds that are slow to heal including chronic wounds and deep dermal wounds that develop hypertrophic scars. This article will review the growing evidence demonstrating the promise of multipotent mesenchymal stem/stromal (MSCs) for the treatment of impaired wound healing. MSCs are often referred to as mesenchymal stem cells despite concerns that these cells are not truly stem cells given the lack of evidence demonstrating self-renewal in vivo. Regardless, abundant evidence demonstrates the therapeutic potential of MSCs for repair and regeneration of damaged tissue due to injury or disease. To date, MSC treatment of acute and chronic wounds results in accelerated wound closure with increased epithelialization, granulation tissue formation and angiogenesis. Although there is evidence for MSC differentiation in the wound, most of the therapeutic effects are likely due to MSCs releasing soluble factors that regulate local cellular responses to cutaneous injury. Important challenges need to be overcome before MSCs can be used effectively to treat wounds that are slow to heal.

American Burn Association practice guidelines burn shock resuscitation.

Abstract : There are insufficient data to support a treatment standard treatment at this time. Guidelines - Adults and children with burns greater than 20% TBSA should undergo formal fluid resuscitation using estimates based on body size and surface area burned. - Common formulas used to initiate of resuscitation estimate a crystalloid need for 2 to 4 ml/kg body weight/%TBSA during the first 24 hours. - Fluid resuscitation,regardless of solution type or estimated need, should be titrated to maintain a urine output of approximately 0.5 1.0 ml/ kg/hr in adults and 1.0 1.5 ml/kg/hr in children. - Maintenance fluids should be administered to children in addition to their calculated fluid requirements caused by injury. - Increased volume requirements can be anticipated in patients with full-thickness injuries, inhalation injury, and a delay in resuscitation. Options - The addition of colloid-containing fluid following burn injury, especially after the first 12 to 24 hours postburn, may decrease overall fluid requirements.

The Association Between Fluid Administration and Outcome Following Major Burn: A Multicenter Study

Objective:To determine patient and injury variables that influence fluid requirements following burn injury and examine the association between fluid volume received and outcome. Background:Fluid resuscitation remains the cornerstone of acute burn management. Recent studies suggest that patients today are receiving more fluid per percent total body surface area (TBSA) than in the past. Therefore, there is a need to better define the factors that impact fluid requirements and to determine the effects of fluid volumes on outcome. Methods:This study was part of a federally funded multicenter study. Multilinear regression analyses were performed to determine the patient and injury characteristics that most influenced fluid resuscitation volumes received. To assess the association of fluid volumes on outcome, propensity scores were developed to provide a predicted volume of fluid for each patient. Logistic models were then used to assess the impact of excess fluid beyond predicted volumes on outcome. Results:Seventy-two patients were included in this analysis. Average patient age was 40.6 years and average TBSA was 44.5%. Average fluid volume received during the first 24 hours after injury was 5.2/mL/kg/TBSA. Significant predictors of fluid received included % TBSA, age, intubation status, and weight. Increased fluid volume received increased risk of development of pneumonia (odds ratio [OR] = 1.92), bloodstream infections (OR =2.33), adult respiratory distress syndrome (OR = 1.55), multiorgan failure (OR= 1.49), and death (OR = 1.74). Conclusion:TBSA, age, weight, and intubation status on admission were significant predictors of fluid received. Patients who received larger volumes of resuscitation fluid were at higher risk for injury complications and death.

Quantitative proteome analysis of human plasma following in vivo lypopolysaccharide administration using 16O/18O labeling and the accurate mass and time tag approach

Identification of novel diagnostic or therapeutic biomarkers from human blood plasma would benefit significantly from quantitative measurements of the proteome constituents over a range of physiological conditions. Herein we describe an initial demonstration of proteome-wide quantitative analysis of human plasma. The approach utilizes postdigestion trypsin-catalyzed 16O/18O peptide labeling, two-dimensional LC-FTICR mass spectrometry, and the accurate mass and time (AMT) tag strategy to identify and quantify peptides/proteins from complex samples. A peptide accurate mass and LC elution time AMT tag data base was initially generated using MS/MS following extensive multidimensional LC separations to provide the basis for subsequent peptide identifications. The AMT tag data base contains >8,000 putative identified peptides, providing 938 confident plasma protein identifications. The quantitative approach was applied without depletion of high abundance proteins for comparative analyses of plasma samples from an individual prior to and 9 h after lipopolysaccharide (LPS) administration. Accurate quantification of changes in protein abundance was demonstrated by both 1:1 labeling of control plasma and the comparison between the plasma samples following LPS administration. A total of 429 distinct plasma proteins were quantified from the comparative analyses, and the protein abundances for 25 proteins, including several known inflammatory response mediators, were observed to change significantly following LPS administration.

High Dynamic Range Characterization of the Trauma Patient Plasma Proteome

Although human plasma represents an attractive sample for disease biomarker discovery, the extreme complexity and large dynamic range in protein concentrations present significant challenges for characterization, candidate biomarker discovery, and validation. Herein we describe a strategy that combines immunoaffinity subtraction and subsequent chemical fractionation based on cysteinyl peptide and N-glycopeptide captures with two-dimensional LC-MS/MS to increase the dynamic range of analysis for plasma. Application of this “divide-and-conquer” strategy to trauma patient plasma significantly improved the overall dynamic range of detection and resulted in confident identification of 22,267 unique peptides from four different peptide populations (cysteinyl peptides, non-cysteinyl peptides, N-glycopeptides, and non-glycopeptides) that covered 3654 different proteins with 1494 proteins identified by multiple peptides. Numerous low abundance proteins were identified, exemplified by 78 “classic” cytokines and cytokine receptors and by 136 human cell differentiation molecules. Additionally a total of 2910 different N-glycopeptides that correspond to 662 N-glycoproteins and 1553 N-glycosylation sites were identified. A panel of the proteins identified in this study is known to be involved in inflammation and immune responses. This study established an extensive reference protein database for trauma patients that provides a foundation for future high throughput quantitative plasma proteomic studies designed to elucidate the mechanisms that underlie systemic inflammatory responses.

Rates, trends, and severity of depression after burn injuries

It is commonly assumed that patients hospitalized for burn treatment will experience some level of depression. However, little is known about the trends in severity of depression over time. The purpose of this study was to determine the rates and severity of depression over a 2-year period. The Beck Depression Inventory was administered at 1 month (N = 151), 1 year (N = 130), and 2 years (N = 125) after discharge. At 1 month, 54% of patients showed symptoms of moderate to severe depression, and at 2 years, 43% of the patients responding still reported moderate to severe depression. The average correlation between scores over time was high. Women had higher depression scores than men at each time period. An interaction between gender and having a head or neck injury was also observed at 1 month and 1 year after discharge. Results suggest that routine outpatient screening for depression is warranted.

Mesenchymal stem cells induce dermal fibroblast responses to injury.

Although bone marrow-derived mesenchymal stem cells have been shown to promote repair when applied to cutaneous wounds, the mechanism for this response remains to be determined. The aim of this study was to determine the effects of paracrine signaling from mesenchymal stem cells on dermal fibroblast responses to injury including proliferation, migration and expression of genes important in wound repair. Dermal fibroblasts were co-cultured with bone marrow-derived mesenchymal stem cells grown in inserts, which allowed for paracrine interactions without direct cell contact. In this co-culture model, bone marrow-derived mesenchymal stem cells regulate dermal fibroblast proliferation, migration and gene expression. When co-cultured with mesenchymal stem cells, dermal fibroblasts show increased proliferation and accelerated migration in a scratch assay. A chemotaxis assay also demonstrated that dermal fibroblasts migrate towards bone marrow-derived mesenchymal stem cells. A PCR array was used to analyze the effect of mesenchymal stem cells on dermal fibroblast gene expression. In response to mesenchymal stem cells, dermal fibroblasts up-regulate integrin alpha 7 expression and down-regulate expression of ICAM1, VCAM1 and MMP11. These observations suggest that mesenchymal stem cells may provide an important early signal for dermal fibroblast responses to cutaneous injury.