Amer Abouhamze

Evidence that brief stress may induce the acute phase response in rats

Exposing rats to a single session of inescapable tail shock (IS) reduces corticosteroid binding globulin (CBG) 24 h later (Fleshner et al., Endocrinology 136: 5336-5342, 1995). The present experiments examined whether reductions in CBG are differentially affected by controllable vs. identical uncontrollable tail shock, are mediated by IS-induced glucocorticoid elevation, or reflect IS-induced activation of the acute phase response and whether IS produces fever. The results demonstrate that 1) equivalent reductions in CBG are observed in response to escapable tail shock or yoked IS, 2) IS-induced CBG reduction is not blocked by adrenalectomy in rats that receive basal corticosteroid replacement or by pretreatment with RU-38486, and 3) IS appears to activate the acute phase response, since IS reduces serum levels of an acute-phase negative reactant (CBG), increases serum levels of acute-phase positive reactants (haptoglobin and alpha 1-acid glycoprotein), and increases core body temperature 20-24 h later.Exposing rats to a single session of inescapable tail shock (IS) reduces corticosteroid binding globulin (CBG) 24 h later (Fleshner et al., Endocrinology 136: 5336-5342, 1995). The present experiments examined whether reductions in CBG are differentially affected by controllable vs. identical uncontrollable tail shock, are mediated by IS-induced glucocorticoid elevation, or reflect IS-induced activation of the acute phase response and whether IS produces fever. The results demonstrate that 1) equivalent reductions in CBG are observed in response to escapable tail shock or yoked IS, 2) IS-induced CBG reduction is not blocked by adrenalectomy in rats that receive basal corticosteroid replacement or by pretreatment with RU-38486, and 3) IS appears to activate the acute phase response, since IS reduces serum levels of an acute-phase negative reactant (CBG), increases serum levels of acute-phase positive reactants (haptoglobin and α1-acid glycoprotein), and increases core body temperature 20-24 h later.

Targeted adenovirus-induced expression of IL-10 decreases thymic apoptosis and improves survival in murine sepsis

Sepsis remains a significant clinical conundrum, and recent clinical trials with anticytokine therapies have produced disappointing results. Animal studies have suggested that increased lymphocyte apoptosis may contribute to sepsis-induced mortality. We report here that inhibition of thymocyte apoptosis by targeted adenovirus-induced thymic expression of human IL-10 reduced blood bacteremia and prevented mortality in sepsis. In contrast, systemic administration of an adenovirus expressing IL-10 was without any protective effect. Improvements in survival were associated with increases in Bcl-2 expression and reductions in caspase-3 activity and thymocyte apoptosis. These studies demonstrate that thymic apoptosis plays a critical role in the pathogenesis of sepsis and identifies a gene therapy approach for its therapeutic intervention.

Visceral ischemia-reperfusion injury promotes tumor necrosis factor (TNF) and interleukin-1 (IL-1) dependent organ injury in the mouse

Acute visceral ischemia and subsequent reperfusion injury, which accompanies the surgical repair of a thoracoabdominal aorta aneurysm, is associated with high rates of morbidity and mortality. The purpose of the present study was to determine whether endogenous tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1) production contributes to organ dysfunction in animals subjected to visceral ischemia secondary to 30 min of supraceliac aortic occlusion. C57BL6/j mice were treated with either a TNF binding protein (TNF-bp-10 mg/kg) or an anti-IL-1 receptor type 1 antibody (150 μg) 2 h prior to 30 min of supraceliac aortic occlusion. An additional group of mice received 30 min of infrarenal aortic occlusion to determine the contribution of lower torso ischemia-reperfusion injury to the changes seen following supraceliac aortic occlusion. Visceral organ ischemia for 30 min produced by supraceliac aortic occlusion followed by 2 h of reperfusion produced measurable TNF-α in 38% of untreated mice, but TNF-α was undetectable in both sham-operated mice and following infrarenal aortic occlusion. After 2 h of reperfusion, lung myeloperoxidase levels were significantly elevated in the mice experiencing visceral ischemia-reperfusion compared with either a sham operation or infrarenal ischemia-reperfusion (11.6 ± 1.3 U/g vs. 3.4 ± .2 U/g and 3.7 ± 1.0 U/g, respectively, p < .05). Pretreatment with TNF-bp and anti-IL-1 antibody decreased lung neutrophil recruitment (7.2 ± 1.2 U/g and 4.6 ± 1.1 U/g) and capillary membrane permeability changes in mice following visceral ischemia-reperfusion. The present study demonstrates that brief (30 min) clinically relevant visceral ischemia produces TNF-α and IL-1 dependent lung injury.

Inhibition of tumor necrosis factor‐α attenuates wound breaking strength in rats

Exogenous administration of tumor necrosis factor‐α has been shown to both enhance and attenuate cutaneous healing in a dose‐dependent manner. We examined the effects of tumor necrosis factor inhibition in the healing wound by both systemic and local administration of tumor necrosis factor‐binding protein. Male Balb/C mice underwent dorsal skin incision with subcutaneous implantation of 20 mg polyvinyl alcohol sponges (4 per animal). In Experiment I, one group (n= 20) received intraperitoneal injections of tumor necrosis factor‐binding protein (3 mg/kg) at the time of wounding, while another group (n= 20) received saline. Four animals from each group were euthanized on days 1, 3, 5, 7, and 14 postwounding. In Experiment II, one group (n= 10) received an intraperitoneal injection of tumor necrosis factor‐binding protein (3 mg/kg) at the time of wounding and every third day thereafter. Another group (n= 10) received an intraperitoneal injection of saline at the time of wounding and every third day thereafter. In Experiment III, one group received a single intraperitoneal injection of tumor necrosis factor‐binding protein (3 mg/kg) at the time of wounding (n= 7), or on postwounding day 4 (n= 7), or day 7 (n= 7). Another group received saline injections at the time of wounding (n= 7), or on postwounding days 4 or 7 (n= 7, respectively). All animals in Experiments II and III were killed at postwounding day 14. Wound breaking strengths were assessed using a tensiometer. Wound fluid collected from the implanted sponges was assayed for tumor necrosis factor‐α and tumor necrosis factor‐binding protein levels using a biological assay and enzyme‐linked immunosorbent assay, respectively. Collagen gene expression in sponge granulomata was assessed by Northern analysis. Collagen deposition in sponges was quantified by measuring hydroxyproline content. Wounds were significantly weaker in the animals that received repeated injections of tumor necrosis factor‐binding protein with a mean wound breaking strength of 93.1 g vs. 186.6 g in controls (p < 0.05). Wound breaking strength in groups that received a single injection of tumor necrosis factor‐binding protein on either day 0, 4, or 7 postwounding were no different than their respective controls. There was no difference in the mean hydroxyproline content of sponges between any of the tumor necrosis factor‐binding protein groups and their respective controls. Northern analysis for collagen I and III expression also revealed no differences. These data indicate that continued systemic administration of tumor necrosis factor‐binding protein resulted in significantly weaker wounds with no corresponding differences in wound collagen content, and collagen gene expression. This suggests that tumor necrosis factor‐α inhibition throughout healing leads to a qualitatively impaired wound without a quantitative alteration in collagen deposition.

Leptin produces anorexia and weight loss without inducing an acute phase response or protein wasting

The ob gene product leptin is known to produce anorexia and loss of body fat when chronically administered to both lean and genetically obese mice. The current study was undertaken to examine whether administration of recombinant leptin in quantities sufficient to produce decreases in food intake and body weight and alterations in body composition would elicit either an hepatic acute phase protein response or preferential loss of carcass lean tissue. Mice were administered increasing quantities of recombinant human leptin or human tumor necrosis factor-α as a positive control. Although leptin (at 10 mg/kg body wt) produced significant anorexia and weight loss (both P < 0.05), human leptin administration did not appear to induce an hepatic acute phase protein response in either lean or genetically obese mice, as determined by protein synthetic rates in the liver or changes in the plasma concentration of the murine acute phase protein reactants, amyloid A, amyloid P, or seromucoid (α1-acid glycoprotein). In addition, human leptin administration did not induce a loss of fat-free dry mass (protein) in lean or obese animals. The findings suggest that at doses adequate to alter food intake and body weight leptin is not a significant inducer of the hepatic acute phase response nor does leptin promote the preferential loss of somatic protein characteristic of a chronic inflammatory process.The ob gene product leptin is known to produce anorexia and loss of body fat when chronically administered to both lean and genetically obese mice. The current study was undertaken to examine whether administration of recombinant leptin in quantities sufficient to produce decreases in food intake and body weight and alterations in body composition would elicit either an hepatic acute phase protein response or preferential loss of carcass lean tissue. Mice were administered increasing quantities of recombinant human leptin or human tumor necrosis factor-alpha as a positive control. Although leptin (at 10 mg/kg body wt) produced significant anorexia and weight loss (both P < 0.05), human leptin administration did not appear to induce an hepatic acute phase protein response in either lean or genetically obese mice, as determined by protein synthetic rates in the liver or changes in the plasma concentration of the murine acute phase protein reactants, amyloid A, amyloid P, or seromucoid (alpha1-acid glycoprotein). In addition, human leptin administration did not induce a loss of fat-free dry mass (protein) in lean or obese animals. The findings suggest that at doses adequate to alter food intake and body weight leptin is not a significant inducer of the hepatic acute phase response nor does leptin promote the preferential loss of somatic protein characteristic of a chronic inflammatory process.

Identification and description of a novel murine model for polytrauma and shock.

Objective:To develop a novel polytrauma model that better recapitulates the immunologic response of the severely injured patient by combining long-bone fracture, muscle tissue damage, and cecectomy with hemorrhagic shock, resulting in an equivalent Injury Severity Score of greater than 15. We compared this new polytrauma/shock model to historically used murine trauma-hemorrhage models. Design:Pre-clinical controlled in vivo laboratory study. Setting:Laboratory of Inflammation Biology and Surgical Science. Subjects:Six- to 10-week-old C57BL/6 (B6) mice. Interventions:Mice underwent 90 minutes of shock (mean arterial pressure 30 mm Hg) and resuscitation via femoral artery cannulation followed by laparotomy (trauma-hemorrhage), hemorrhage with laparotomy and femur fracture, or laparotomy with cecetomy and femur fracture with muscle tissue damage (polytrauma). Mice were euthanized at 2 hours, 1 day, and 3 days postinjury. Measurements and Main Results:The spleen, bone marrow, blood, and serum were collected from mice for analysis at the above time points. None of the models were lethal. Mice undergoing polytrauma exhibited a more robust inflammatory response with significant elevations in cytokine/chemokine concentrations when compared with traditional models. Polytrauma was the only model to induce neutrophilia (Ly6G+CD11b+ cells) on days 1 and 3 (p < 0.05). Polytrauma, as compared to trauma-hemorrhage and hemorrhage with laparotomy and femur fracture, induced a loss of circulating CD4+ T cell with simultaneous increased cell activation (CD69+ and CD25+), similar to human trauma. There was a prolonged loss of major histocompatibility complex class II expression on monocytes in the polytrauma model (p < 0.05). Results were confirmed by genome-wide expression analysis that revealed a greater magnitude and duration of blood leukocyte gene expression changes in the polytrauma model than the trauma-hemorrhage and sham models. Conclusions:This novel polytrauma model better replicates the human leukocyte, cytokine, and overall inflammatory response following injury and hemorrhagic shock.

Microfluidic Leukocyte Isolation for Gene Expression Analysis in Critically Ill Hospitalized Patients

BACKGROUND Microarray technology is becoming a powerful tool for diagnostic, therapeutic, and prognostic applications. There is at present no consensus regarding the optimal technique to isolate nucleic acids from blood leukocyte populations for subsequent expression analyses. Current collection and processing techniques pose significant challenges in the clinical setting. Here, we report the clinical validation of a novel microfluidic leukocyte nucleic acid isolation technique for gene expression analysis from critically ill, hospitalized patients that can be readily used on small volumes of blood. METHODS We processed whole blood from hospitalized patients after burn injury and severe blunt trauma according to the microfluidic and standard macroscale leukocyte isolation protocol. Side-by-side comparison of RNA quantity, quality, and genome-wide expression patterns was used to clinically validate the microfluidic technique. RESULTS When the microfluidic protocol was used for processing, sufficient amounts of total RNA were obtained for genome-wide expression analysis from 0.5 mL whole blood. We found that the leukocyte expression patterns from samples processed using the 2 protocols were concordant, and there was less variability introduced as a result of harvesting method than there existed between individuals. CONCLUSIONS The novel microfluidic approach achieves leukocyte isolation in <25 min, and the quality of nucleic acids and genome expression analysis is equivalent to or surpasses that obtained from macroscale approaches. Microfluidics can significantly improve the isolation of blood leukocytes for genomic analyses in the clinical setting.

Microfluidics-based capture of human neutrophils for expression analysis in blood and bronchoalveolar lavage.

Gene expression analysis can be a powerful tool in predicting patient outcomes and identifying patients who may benefit from targeted therapies. However, isolating human blood polymorphonuclear cells (PMNs) for genomic analysis has been challenging. We used a novel microfluidic technique that isolates PMNs by capturing CD66b+ cells and compared it with dextran-Ficoll gradient isolation. We also used microfluidic isolation techniques for blood and bronchoalveolar lavage (BAL) samples of patients with acute respiratory distress syndrome (ARDS) to evaluate PMN genomic alterations secondary to pulmonary sequestration. PMNs obtained from ex vivo lipopolysaccharide (LPS)-stimulated or -unstimulated whole blood from five healthy volunteers were isolated by either dextran-Ficoll gradient, microfluidics capture, or a combination of the two techniques. Blood and BAL fluid PMNs were also isolated using microfluidics from seven hospitalized patients with ARDS. Gene expression was inferred from extracted RNA using Affymetrix U133 Plus 2.0 GeneChips. All methods of PMN isolation produced similar quantities of high-quality RNA, when adjusted for recovered cell number. Unsupervised analysis and hierarchical clustering indicated that LPS stimulation was the primary factor affecting gene expression patterns among all ex vivo samples. Patterns of gene expression from blood and BAL PMNs differed significantly from each other in the patients with ARDS. Isolation of PMNs by microfluidics can be applied to both blood and BAL specimens from critically ill, hospitalized patients. Unique genomic expression patterns are obtained from the blood and BAL fluid of critically ill patients with ARDS, and these differ significantly from genomic patterns seen after ex vivo LPS stimulation.