Effect of thermal injury on the expression of transcription factors that regulate acute phase response genes: the response of C/EBP alpha, C/EBP beta, and C/EBP delta to thermal injury

Biological roles of CCAAT/Enhancer-binding protein delta during inflammation

CCAAT/enhancer-binding protein delta (CEBPD) belongs to the CCAAT/enhancer-binding protein family, and these proteins function as transcription factors in many biological processes, including cell differentiation, motility, growth arrest, proliferation, cell death, metabolism and immune responses. The functional diversity of CEBPD depends, in part, on the cell type and cellular context, which indicates that CEBPD could interpret a variety of cues to adjust cellular responses in specific situations. Here, we review the regulation of the CEBPD gene and its function in response to inflammatory stimuli. We also address its effects in inflammation-related diseases through a discussion of its recently discovered downstream targets. Regarding to the previous discoveries and new insights in inflammation-associated diseases, suggesting CEBPD could also be a central gene in inflammation. Importantly, the results of this study indicate that the investigation of CEBPD could open a new avenue to help better understand the inflammatory response.

Lipopolysaccharide-induced failure of the gut barrier is site-specific and inhibitable by growth hormone

BACKGROUND

Gut barrier failure caused by endotoxemia is a life-threatening problem. The present study aimed to determine whether any specific intestinal site is highly correlated with gut barrier failure, and whether recombinant human growth hormone (rhGH) can ameliorate gut barrier failure in a rat model of endotoxemia.

METHODS

Enterostomy tubes were surgically placed in adult male Sprague-Dawley rats three days before induction of endotoxemia by lipopolysaccharide (LPS) injection. Controls received no LPS. Rats were then randomly assigned to receive subcutaneous injections of rhGH (experimental, n = 30) or 0.9 % saline (control, n = 15) at 24, 48, or 72 h after LPS injection. Escherichia coli labeled with green fluorescent protein (GFP) were injected into the intestinal segment of all rats through the enterostomy tubes. The number of GFP-labeled E. coli detected in mesenteric lymph nodes was examined after 96 h. Apoptosis and proliferation rates of intestinal epithelial cells, and intestinal permeability were measured.

RESULTS

Endotoxemia led to high mortality, compared with the control group, and rhGH treatment did not improve survival. Intestinal permeability, reflected by translocation rates of GFP-labeled E. coli, and apoptosis rates in the LPS-induced endotoxemia group were higher than those in the non-endotoxemia control group, and the endotoxemia ileum group had the highest rates of both bacterial translocation and apoptosis. The LPS+GH group had less bacterial translocation and apoptosis than the LPS-induced endotoxemia group. In contrast, the proliferation rates were lower in the LPS group compared to the LPS+GH group.

CONCLUSIONS

Endotoxemia can induce gut barrier failure in rats, and the ileum is the site of greatest risk. The GH can reduce the incidence of endotoxemia-induced gut barrier failure, but not the associated mortality.

The hepatic response to thermal injury: is the liver important for postburn outcomes?

Thermal injury produces a profound hypermetabolic and hypercatabolic stress response characterized by increased endogenous glucose production via gluconeogenesis and glycogenolysis, lipolysis, and proteolysis. The liver is the central body organ involved in these metabolic responses. It is suggested that the liver, with its metabolic, inflammatory, immune, and acute phase functions, plays a pivotal role in patient survival and recovery by modulating multiple pathways following thermal injury. Studies have evaluated the role and function of the liver during the postburn response and showed that liver integrity and function are essential for survival, and that hepatic acute phase proteins are strong predictors for postburn survival. This review discusses these studies and delineates the pivotal role of the liver in patients following severe thermal injury.

Combination of recombinant human growth hormone and propranolol decreases hypermetabolism and inflammation in severely burned children

OBJECTIVE

Recombinant human growth hormone (rhGH) is a salutary modulator of posttraumatic metabolic responses. However, rhGH administration is associated with deleterious side effects, such as hyperglycemia, increased free fatty acids, and triglycerides, which limit its use. Administration of beta-blocker attenuates cardiac work and resting energy expenditure after severe thermal injury and improves fat metabolism and insulin sensitivity. Therefore, the combination of rhGH plus propranolol appears ideal. The aim of the present study was to determine whether rhGH plus propranolol improves hypermetabolism and the inflammatory and acute phase response after severe burn without causing adverse side effects.

DESIGN

Prospective randomized control trial.

SETTING

Shriners Hospitals for Children.

PATIENTS

Fifteen pediatric patients with burns > 40% total body surface area, 0.1-16 yrs of age, admitted within 7 days after burn. Fifteen children were matched for burn size, age, gender, inhalation injury, and infection and served as controls.

INTERVENTIONS

Patients in the experimental group received rhGH (0.2 mg/kg/day) and propranolol (to decrease heart rate by 15%) for > or = 15 days.

MEASUREMENTS AND MAIN RESULTS

Outcome measurements included resting energy expenditure, body composition, acute phase proteins, and cytokines. Both cohorts were similar in age, burn size, gender, and accompanying injuries. Percent predicted resting energy expenditure significantly decreased in patients receiving rhGH/propranolol (Delta -5% +/- 8%) compared with controls (Delta +35% +/- 20%) (p < .05). rhGH/propranolol administration significantly decreased serum C-reactive protein, cortisone, aspartate aminotransferase, alanine aminotransferase, free fatty acids, interleukin-6, interleukin-8, and macrophage inflammatory protein-1beta when compared with controls, while growth hormone/propranolol increased serum insulin-like growth factor-I, insulin-like growth factor binding protein-3, growth hormone, prealbumin, and interleukin-7 when compared with placebo (p < .05).

CONCLUSIONS

rhGH in combination with propranolol attenuates hypermetabolism and inflammation without the adverse side effects found with rhGH therapy alone.

Growth hormone prevents acute liver injury induced by cardiopulmonary bypass in a rat model

OBJECTIVE

Cardiopulmonary bypass-induced acute liver injury is a life-threatening complication thought to be associated with the inflammatory response and the acute-phase response. Recombinant human growth hormone can modulate the acute-phase response and inflammatory response. We tested the protective effect of growth hormone on cardiopulmonary bypass-induced liver injury in the rat.

METHODS

Adult male Sprague-Dawley rats (group G received 2.5 mg/kg recombinant human growth hormone intramuscularly at 8 am every 24 hours for 3 days and just before the initiation of cardiopulmonary bypass; group C served as a control group) underwent cardiopulmonary bypass (120 minutes, 120 mL x kg(-1) x min(-1), 34 degrees C) and were killed 3 hours after the termination of cardiopulmonary bypass.

RESULTS

Administration of recombinant human growth hormone markedly increased serum insulin-like growth factor and insulin-like growth factor-binding protein 3 levels compared with those seen in group C. Group G showed significantly lower serum concentrations of alanine aminotransferase and total bilirubin after cardiopulmonary bypass termination. Those receiving recombinant human growth hormone demonstrated a significant increase in serum prealbumin and transferrin levels and a marked decrease in serum amyloid A and C-reactive protein levels. Recombinant human growth hormone significantly decreased serum tumor necrosis factor alpha and interleukin 1beta levels, whereas no changes were found for serum interleukin 6 and interleukin 10 levels. Recombinant human growth hormone significantly increased total liver protein content and hepatocyte proliferation and decreased hepatocyte apoptosis versus values seen in group C.

CONCLUSIONS

These results suggest that growth hormone prevents cardiopulmonary bypass-induced acute liver injury in a rat model through decreases in acute-phase proteins, proinflammatory cytokines tumor necrosis factor alpha and interleukin 1beta, and hepatocyte apoptosis, which is associated with increases in constitutive hepatic proteins, total liver protein content, and hepatocyte proliferation. This strategy of pretreatment with growth hormone might be a prospective management for preventing acute liver injury when major cardiac surgery with cardiopulmonary bypass is performed.

Evolutionary-conserved gene expression response profiles across mammalian tissues

Gene expression responses are complex and frequently involve the actions of many genes to effect coordinated patterns. We hypothesized these coordinated responses are evolutionarily conserved and used a comparison of human and mouse gene expression profiles to identify the most prominent conserved features across a set of normal mammalian tissues. Based on data from multiple studies across multiple tissues in human and mouse, 13 gene expression modes across multiple tissues were identified in each of these species using principal component analysis. Strikingly, 1-to-1 pairing of human and mouse modes was observed in 12 out of 13 modes obtained from the two species independently. These paired modes define evolutionarily conserved gene expression response modes (CGEMs). Notably, in this study we were able to extract biological responses that are not overwhelmed by laboratory-to-laboratory or species-to-species variation. Of the variation in our gene expression dataset, 84% can be explained using these CGEMs. Functional annotation was performed using Gene Ontology, pathway, and transcription factor binding site over representation. Our conclusion is that we found an unbiased way of obtaining conserved gene response modes that accounts for a considerable portion of gene expression variation in a given dataset, as well as validates the conservation of major gene expression response modes across the mammals.

Local and distant burn injury alter immuno-inflammatory gene expression in skeletal muscle

BACKGROUND

Severe burn trauma mediates immune dysfunction, infection, and multiple organ dysfunction syndrome. We are investigating the immuno-inflammatory response by characterizing gene expression changes in skeletal muscle after local and distant burn injury.

METHODS

Male CD1 mice in three experimental groups, control (unburned), hind limb (local burn), and 30% total body surface area (distant burn), were killed between 6 hours and 10 days postburn; and changes in gastrocnemius muscle global gene expression were assessed using microarrays.

RESULTS

The 35 immuno-inflammatory genes are differentially expressed in both models, with an additional 20 and 30 genes specific to distant and local burn, respectively. These genes encode chemokines, oxidative-stress, complement, and defense/immune functions.

CONCLUSION

Burn mediates a common systemic response, independent of the site or extent of injury, and also specific responses to local versus distant trauma. A transcriptome profile of genes that initiate and sustain systemic inflammation has been identified.

Effect of Ligustrazine on liver injury after burn trauma

This study was designed to investigate the effect of Ligustrazine on burn-induced liver injury as well as the activation of nuclear factor kappaB (NF-kappaB) in severely burned rats. Sprague-Dawley rats were divided into three groups: (1) sham group, rats who underwent sham burn; (2) control group, rats given third-degree burns over 30% total body surface area (TBSA) and lactated Ringer solution for resuscitation; (3) Ligustrazine group, rats given burn and lactated Ringer's solution with Ligustrazine inside for resuscitation. Liver injury was assessed at 24 h post-burn by serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), as well as liver wet/dry weight ratio. Liver myeloperoxidase (MPO) activity was also analyzed. Hepatic NF-kappaB activity was examined by electrophoretic mobility shift assay (EMSA). Burn results in hepatic dysfunction and increased hepatic NF-kappaB activity, elevated liver wet/dry ratio and hepatic MPO activity. Ligustrazine inhibited these changes and alleviated burn-mediated hepatic dysfunction. The data indicated that Ligustrazine has a protective effect on burn-induced liver injury and possible mechanism may be attributed to its inhibitory action on the activation of NF-kappaB following burn trauma.

Co-ordinate but disproportionate activation of apoptotic, regenerative and inflammatory pathways characterizes the liver response to acute amebic infection

The liver has the remarkable ability to respond to injury with repair and regeneration. The protozoan parasite Entamoeba histolytica is the major cause of liver abscess worldwide. We report a transcriptional analysis of the response of mouse liver to E. histolytica infection, the first study looking at acute liver infection by a non-viral pathogen. Focusing on early time points, we identified 764 genes with altered transcriptional levels in amebic liver abscess. The response to infection is rapid and complex, with concurrent increased expression of genes linked to host defence through IL-1, TLR2, or interferon-induced pathways, liver regeneration via activation of IL-6 pathways, and genes associated with programmed cell death possibly through TNFalpha or Fas pathways. A comparison of amebic liver infection with the liver response to partial hepatectomy or toxins reveals striking similarities between amebic liver abscess and non-infectious injury in key components of the liver regeneration pathways. However, the response in amebic liver abscess is biased towards apoptosis when compared with acute liver injury from hepatectomy, toxins, or other forms of liver infection. E. histolytica infection of the liver simultaneously activates inflammatory, regenerative and apoptotic pathways, but the sum of these early responses is biased towards programmed cell death.

A Gene Expression Signature for Relapse of Primary Wilms Tumors

Anaplastic histology and metastasis are each associated with higher relapse and mortality rates in Wilms tumor patients. However, not all anaplastic tumors relapse and some nonanaplastic tumors relapse unexpectedly. To identify more accurate early prognostic indicators, we analyzed expression of 4,900 cancer-related genes in 26 primary Wilms tumors. This analysis revealed that expression of a set of four genes predicts future relapse of primary Wilms tumors with high accuracy, independent of anaplasia. Random permutation testing of this prognostic gene expression signature yielded P = 0.003. Real-time reverse transcription-PCR analysis of the four genes in an independent primary tumor set resulted in correct prediction of future relapse with an accuracy of 92%. One of the four genes in the prognostic signature, CCAAT/enhancer binding protein beta (C/EBPB), is expressed at higher levels in both primary relapsing tumors and metastatic tumors than in primary nonrelapsing tumors. Short interfering RNA-mediated down-regulation of C/EBPB expression in WiT49, a cell line derived from a metastatic Wilms tumor, resulted in spontaneous apoptosis. These findings suggest that C/EBPB is a critical survival factor for Wilms tumor cells and that its expression contributes to the prognosis of Wilms tumor patients.

Liver-enriched transcription factors in liver function and development. Part II: the C/EBPs and D site-binding protein in cell cycle control, carcinogenesis, circadian gene regulation, liver regeneration, apoptosis, and liver-specific gene regulation

In the first part of our review (see Pharmacol Rev 2002;54:129-158), we discussed the basic principles of gene transcription and the complex interactions within the network of hepatocyte nuclear factors, coactivators, ligands, and corepressors in targeted liver-specific gene expression. Now we summarize the role of basic region/leucine zipper protein family members and particularly the albumin D site-binding protein (DBP) and the CAAT/enhancer-binding proteins (C/EBPs) for their importance in liver-specific gene expression and their role in liver function and development. Specifically, regulatory networks and molecular interactions were examined in detail, and the experimental findings summarized in this review point to pivotal roles of DBP and C/EBPs in cell cycle control, carcinogenesis, circadian gene regulation, liver regeneration, apoptosis, and liver-specific gene regulation. These regulatory proteins are therefore of great importance in liver physiology, liver disease, and liver development. Furthermore, interpretation of the vast data generated by novel genomic platform technologies requires a thorough understanding of regulatory networks and particularly the hierarchies that govern transcription and translation of proteins as well as intracellular protein modifications. Thus, this review aims to stimulate discussions on directions of future research and particularly the identification of molecular targets for pharmacological intervention of liver disease.

Insulin attenuates the systemic inflammatory response in endotoxemic rats

Insulin decreases the mortality and prevents the incidence of infection and sepsis in critically ill patients. The molecular and cellular mechanisms by which insulin improves survival have not been defined. The purpose of the present study was to determine the effect of insulin on the inflammatory reaction during endotoxemia. Endotoxemic rats were randomly divided into two groups to receive either saline or insulin. The effects of insulin on hepatic signal transcription factor mRNA expression, proinflammatory and antiinflammatory cytokine mRNA and protein concentration were determined. Insulin administration did not change glucose or electrolyte levels, but significantly decreased proinflammatory signal transcription factors [CCAAT/enhancer-binding protein-beta, signal transducer and activator of transcription-3 and-5, RANTES (regulated on activation, normal T cell expressed and secreted)] and cytokine expression in the liver and serum levels of IL-1beta, IL-6, macrophage inflammatory factor, and TNFalpha. Insulin administration further decreased high mobility group 1 protein in the serum compared with controls. In addition, insulin increased antiinflammatory cytokine expression in the liver; serum levels of IL-2, IL-4, and IL-10; and hepatic suppressor of cytokine signaling-3 mRNA expression. Insulin modulates the inflammatory response by decreasing the proinflammatory and increasing the antiinflammatory cascade. Because glucose and electrolyte levels did not differ between insulin-treated patients and controls, we hypothesize that the effects are direct antiinflammatory mechanisms of insulin, rather than indirect, through modulation of glucose or electrolyte metabolism.

Liposome-mediated transfer of vascular endothelial growth factor cDNA augments survival of random-pattern skin flaps in the rat

Tissue engineering is an application for gene therapy that is in its infancy. We show that simple liposomal-mediated gene transfer could result in a potentially useful biological effect in the field of wound healing. cDNA encoding the 165 amino acid form of vascular endothelial growth factor complexed to commercially available liposomes was injected into rat skin 1 week before raising a random pattern 3 x 10 cm flap. The flap survival was enhanced by 14 percent, and was accomplished without accessing the arterial inflow of the territory. These results were statistically significant (p<0.002) and reproducible. No adverse effects were seen. Histological analysis of the angiogenesis localized much of the new vessel formation to the area around the hair follicles. Polymerase chain reaction amplification of extracted flap tissue confirmed the presence of the transgene.

Gene expression profiles of livers from thermally injured rats

The liver plays an important role in a severe thermal injury by modulating immune function, inflammatory processes and the acute phase response, which are an orchestrated attempt to restore homeostasis. Using high-density oligonucleotide arrays, we examined the gene expression profile in the livers of rats between 2 and 240 h after a 40% total body surface area (TBSA) burn. Alterations in gene expression unique to a thermal injury were identified. Approximately 39 genes out of 8700 genes on each array across all the time points showed a significant change in expression patterns. Real time reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analyses verified significant changes in early growth response-1 (Egr-1) messenger RNA (mRNA) and protein levels corresponding to the array data. Significant increases in serum levels of alpha-2-macroglobulin that correspond to changes in its mRNA levels were observed at 6 and 24 h after burn, p<0.05. The genomic pattern for liver in the hypermetabolic phase after the burn injury involves transcription factors, stress and inflammatory responses, cytoskeletal and extracellular matrix modifications, and regulation of cell proliferation and differentiation. During the initial phase of thermal injury gene expression profiles in the liver may provide some insight into how cellular protection mechanisms and systemic hypermetabolism are initiated and controlled. The genome wide changes observed may provide a rational therapeutic strategy to improve burn care.

Differences in the Hepatic Signal Transcription Pathway and Cytokine Expression Between Thermal Injury and Sepsis

Inflammation and catabolism in response to trauma, surgery, critical illness or bacteria lead to a compromise of essential organs, which can lead to prolonged clinical stay and even death. Mediators responsible for catabolism were thought to be proinflammatory cytokines, but recently the focus has shifted to signal transduction. The purpose of the present study was to determine differences between two pathophysiologic states, sepsis and thermal injury, in signal transduction and cytokine expression and thus define the importance of the signal transcription pathway. Rats were randomly divided to either receive lipopolysaccharide (3 mg/kg body weight or a 30% total body surface area burn) or they received no treatment and served as controls. Animals were sacrificed 1, 2, 5, and 7 days postinsult and serum and liver harvested for analysis. A thermal injury appeared to have a slow release and expression of signal transcription factors and cytokines and a sepsis showed a rapid increase of mediators and also a fast decrease. The changes in cytokine profiles after burn, particularly interleukin-1beta and macrophage inhibitory factor, appear to be mediated by C/EBP-beta and STAT-3, whereas after the induction of a sepsis, tumor necrosis factor and interleukin-6 are mainly mediated by STAT-5. Based on our findings we suggest that the pathophysiologic state of a thermal injury is not comparable with sepsis in association with signal transcription factors and the differences in intracellular and extracellular signaling therefore opens new ideas for therapeutic options.

IL-1beta activates C/EBP-beta and delta in human enterocytes through a mitogen-activated protein kinase signaling pathway

The enterocyte is an active participant in the inflammatory and metabolic response to sepsis, endotoxemia and other critical illnesses and is the site for cytokine and acute phase protein production in these conditions. The role of the CCAAT/enhancer binding protein (C/EBP) family of transcription factors in the response to inflammatory stimuli in the enterocyte is not well understood. In the present study, we treated Caco-2 cells with IL-1beta and determined C/EBP DNA binding activity by electrophoretic mobility shift assay. The involvement of the alpha, beta, and delta isoforms was determined by supershift analysis and Western blot analysis of proteins from the nuclear fraction. The role of the mitogen-activated protein kinase (MAPK) signaling pathway was assessed by treating cells with the MAPK inhibitor PD-98059. Treatment of the Caco-2 cells with IL-1beta resulted in increased CCAAT/enhancer binding protein DNA binding activity. Supershift analysis and Western blotting indicated that this response to IL-1beta mainly reflected the delta isoform, and to a lesser degree the beta isoform. Treatment of the cells with PD-98059 inhibited the IL-1beta-induced increase in beta and delta activity. The results suggest that members of the CCAAT/enhancer binding protein family of transcription factors are activated in enterocytes during inflammatory conditions characterized by high levels of IL-1beta.

C/EBP DNA-binding activity is upregulated by a glucocorticoid-dependent mechanism in septic muscle

Sepsis-induced muscle cachexia is associated with increased expression of several genes in the ubiquitin-proteasome proteolytic pathway, but little is known about the activation of transcription factors in skeletal muscle during sepsis. We tested the hypothesis that sepsis upregulates the expression and activity of the transcription factors CCAAT/enhancer binding protein (C/EBP)-beta and -delta in skeletal muscle. Sepsis was induced in rats by cecal ligation and puncture, and control rats were sham operated. C/EBP-beta and -delta DNA-binding activity was determined by electrophoretic mobility shift assay and supershift analysis. In addition, C/EBP-beta and -delta nuclear protein levels were determined by Western blot analysis. Sepsis resulted in increased DNA-binding activity of C/EBP, and supershift analysis suggested that this reflected activation of the beta- and delta-isoforms of C/EBP. Concomitantly, C/EBP-beta and -delta protein levels were increased in the nuclear fraction of skeletal muscle. In additional experiments, we tested the role of glucocorticoids in sepsis-induced activation of C/EBP-beta and -delta by treating rats with the glucocorticoid receptor antagonist RU-38486. This treatment inhibited the sepsis-induced activation of C/EBP-beta and -delta, suggesting that glucocorticoids participate in the upregulation of C/EBP in skeletal muscle during sepsis. The present results suggest that C/EBP-beta and -delta are activated in skeletal muscle during sepsis and that this response is, at least in part, regulated by glucocorticoids.

Modulation of types I and II acute phase reactants with insulin-like growth factor-1/binding protein-3 complex in severely burned children

OBJECTIVE

To determine whether 0.5 mg/kg insulin-like growth factor (IGF)-1/binding protein (IGFBP)-3, given intravenously, effectively alters the acute phase response in severely burned children.

DESIGN

Longitudinal trial with each patient serving as their own control.

SETTING

University-affiliated pediatric bum center.

PATIENTS

Nine children, 15 yrs of age or less, with burns covering >40% of the total body surface area.

INTERVENTIONS

Standard burn care with early burn wound excision and grafting. Blood sampled at defined time points before and after operative procedures.

MEASUREMENTS AND RESULTS

Determination of types I and II acute phase reactant proteins, constitutive serum proteins, serum cytokines, serum IGF-1, IGFBP-3, and growth hormone levels. Treatment with IGF-1/BP-3 attenuated increases in type I (complement 3, alpha1-acidglycoprotein) and type II (haptoglobin, alpha1-antitrypsin) acute phase proteins. Further, IGF-1/BP-3 increased constitutive serum protein levels (prealbumin, retinol binding protein, transferrin) and decreased serum IL-6 levels.

CONCLUSIONS

Low-dose IGF-1/BP-3 effectively attenuated the type I and type II hepatic acute phase response, increased serum levels of constitutive proteins, and modulated the hypermetabolic response.

Runt domain factor (Runx)-dependent effects on CCAAT/ enhancer-binding protein delta expression and activity in osteoblasts

Transcription factor CCAAT/enhancer-binding protein delta (C/EBPdelta) is normally associated with acute-phase gene expression. However, it is expressed constitutively in primary osteoblast cultures where it increases insulin-like growth factor I synthesis in a cAMP-dependent way. Here we show that the 3' proximal region of the C/EBPdelta gene promoter contains a binding sequence for Runt domain factor Runx2, which is essential for osteogenesis. This region of the C/EBPdelta promoter directed high reporter gene expression in osteoblasts, and specifically bound Runx2 in osteoblast-derived nuclear extract. C/EBPdelta gene promoter activity was reduced by mutating the Runx binding sequence or by co-transfecting with Runx2 antisense expression plasmid, and was enhanced by overexpression of Runx-2. Exposure to prostaglandin E(2) increased Runx-dependent gene transactivation independently of Runx2 binding to DNA. Runx2 bound directly to the carboxyl-terminal region of C/EBPdelta itself, and its ability to drive C/EBPdelta expression was suppressed when C/EBPdelta or its carboxyl-terminal fragment was increased by overexpression. Consistent effects also occurred on C/EBPdelta-dependent increases in gene expression driven by synthetic or insulin-like growth factor I gene promoter fragments. These interactions between Runx2 and C/EBPdelta, and their activation by prostaglandin E(2), provide new evidence for their importance during skeletal remodeling, inflammatory bone disease, or fracture repair.

Recombinant human growth hormone treatment in pediatric burn patients and its role during the hepatic acute phase response

OBJECTIVE

Recombinant human growth hormone (rHGH) has been shown to increase mortality in adult trauma patients; however, little has been reported on its side effects in children. The acute phase response has been suggested to be a contributing factor to trauma mortality. Therefore, the purpose of this study was to examine the effects of exogenous rHGH on the acute phase response in pediatric bum patients.

DESIGN

Prospective, randomized, double-blind study.

SETTING

Shriners Hospital for Children.

PATIENTS

Thermally injured pediatric patients, ranging in age from 0.1 to 16 yrs.

INTERVENTIONS

Twenty-eight thermally injured children received either 0.2 mg/kg/day of rHGH or saline (placebo) within 3 days of admission and for at least 25 days.

MEASUREMENTS AND MAIN RESULTS

Measurements were patient demographics, incidence of sepsis, inhalation injury, mortality, serum constitutive proteins, acute phase proteins, proinflammatory cytokines and insulin-like growth factor-I (IGF-I), insulin-like growth factor binding protein (IGFBP)-1, and IGFBP-3. No differences could be demonstrated in age, gender, burn size, incidence in sepsis (20% vs. 26%), inhalation injury (46% vs. 27%), or mortality (8% vs. 7%) between those receiving rHGH or placebo. Serum IGF-I and IGFBP-3 increased with rHGH treatment, whereas serum IGFBP-1 decreased compared with placebo (p < .05). Burned children treated with rHGH required significantly less albumin substitution to maintain normal levels compared with placebo (p < .05). Those receiving rHGH demonstrated a decrease in serum C-reactive protein and serum amyloid-A and an increase in serum retinol-binding protein compared with placebo (p < .05). rHGH decreased serum tumor necrosis factor-alpha and interleukin (IL)-1beta, whereas no changes were found for serum IL-1alpha, IL-6, and IL-10 compared with placebo (p < .05). Free fatty acids were elevated in burned children who received rHGH (p < .05).

CONCLUSION

Data indicate that rHGH does not increase mortality. rHGH decreased acute phase proteins, tumor necrosis factor-alpha, and IL-1beta, which is associated with increases in constitutive hepatic proteins and IGF-I.

Regulation of the mammalian alcohol dehydrogenase genes

This review focuses on the regulation of the mammalian medium-chain alcohol dehydrogenase (ADH) genes. This family of genes encodes enzymes involved in the reversible oxidation of alcohols to aldehydes. Interest in these enzymes is increased because of their role in the metabolism of beverage alcohol as well as retinol, and their influence on the risk for alcoholism. There are six known classes ADH genes that evolved from a common ancestor. ADH genes differ in their patterns of expression: most are expressed in overlapping tissue-specific patterns, but class III ADH genes are expressed ubiquitously. All have proximal promoters with multiple cis-acting elements. These elements, and the transcription factors that can interact with them, are being defined. Subtle differences in sequence can affect affinity for these factors, and thereby influence the expression of the genes. This provides an interesting system in which to examine the evolution of tissue specificity. Among transcription factors that are important in multiple members of this gene family are the C/EBPs, Sp1,USF, and AP1, HNF-1, CTF/NF-1, glucocorticoid, and retinoic acid receptors, and several as-yet unidentified negative elements, are important in at least one of the genes. There is evidence that cis-acting elements located far from the proximal promoter are necessary for proper expression. Three of the genes have upstream AUGs in the 5' nontranslated regions of their mRNA, unusual for mammalian genes. The upstream AUGs have been shown to significantly affect expression of the human ADH5 gene.

Insulin-like growth factor I in combination with insulin-like growth factor binding protein 3 affects the hepatic acute phase response and hepatic morphology in thermally injured rats

OBJECTIVE

To modulate the hepatic acute phase response after a thermal injury by the administration of insulin-like growth factor I (IGF-I) in combination with its principal binding protein 3 (IGFBP-3).

SUMMARY BACKGROUND DATA

The hepatic acute phase response is a cascade of events initiated to restore homeostasis after trauma; however, a prolonged response contributes to multiorgan failure, hypermetabolism, complications, and death. Although IGF-1 has been shown to improve cell recovery and play a major role in liver regeneration, its effect on the hepatic acute phase response is not known.

METHODS

Sprague-Dawley rats (56 males) received a 60% total body surface area third-degree scald burn and were randomly divided to receive either rhIGF-I/BP-3 (10 mg/kg/day given subcutaneously) or saline (control). Rats were killed on postburn days 1, 2, 5, and 7 and serum glucose, electrolytes, acute phase reactant proteins, tumor necrosis factor alpha, interleukin 1 beta, interleukin 6, and rat and human serum IGF-I and IGFBP-3 were measured. Hepatic protein concentrations, hepatocyte proliferation, and hepatocyte apoptosis were determined.

RESULTS

No hypoglycemia or electrolyte imbalance could be shown in rats receiving the growth factor complex compared with saline. rhIGF-I/BP-3 increased serum protein on postburn days 2 and 7, albumin on days 5 and 7, and transferrin on days 1, 5, and 7, and decreased haptoglobin and alpha1-acid glycoprotein on postburn days 5 and 7 compared with controls. IGF-I/ BP-3 had no effect on type II acute phase proteins. Rats receiving IGF-I/BP-3 had lower serum levels of interleukin 1 beta and tumor necrosis factor alpha on the first day after burn compared with controls, whereas serum levels of interleukin 6 did not change. rhIGF-I/BP-3 significantly increased total liver protein content on postburn days 1, 2, 5, and 7 compared with controls. IGF-I/BP-3 increased hepatocyte proliferation and decreased hepatocyte apoptosis versus controls.

CONCLUSION

In combination with its principal binding protein, rhIGF-I decreases the proinflammatory cytokines interleukin 1 beta and tumor necrosis factor alpha, followed by a decrease in type I acute phase proteins. IGF-I/BP-3 had no effect on interleukin 6 and type II acute phase proteins. Decreases in acute phase protein and proinflammatory cytokine synthesis were associated with increases in constitutive hepatic proteins, total liver protein content, and hepatocyte proliferation. IGF-I/BP-3 attenuates the hypermetabolic response after thermal injury and may improve the clinical outcome.

Hepatocyte growth factor modulates the hepatic acute-phase response in thermally injured rats

OBJECTIVE

Hepatocyte growth factor (HGF) has been shown to modulate the acute-phase response in vitro. The specific in vivo role of HGF in this multifactorial response, however, remains unknown. This study examines the effects of exogenous HGF on the acute-phase response in thermally injured rats.

DESIGN

Prospective, randomized, laboratory study.

SETTINGS

Shriners Hospital for Children and University of Texas Medical Branch laboratories.

SUBJECTS

Fifty-six male Sprague-Dawley rats (weight range, 300-325 g).

INTERVENTION

Animals received a 60% total body surface area third-degree scald burn and were randomly divided to receive either 400 microg/kg/day i.v. HGF or saline (control).

MEASUREMENTS AND MAIN RESULTS

Serum acute-phase proteins, cytokines, and insulin-like growth factor (IGF)-I concentrations, as well as liver weight, protein and triglyceride content, IGF-I concentrations, and cytokine gene expression were measured 1, 2, 5, or 7 days after burn. Serum albumin was increased on days 2, 5, and 7 after burn, and transferrin was increased on day 7 after burn in HGF-treated rats compared with controls (p<.05). HGF increased alpha2-macroglobulin concentrations on postburn days 2, 5, and 7 compared with controls (p<.05). Serum interleukin-6 and tumor necrosis factor-alpha were significantly higher within 2 days of burn in rats treated with HGF (p<.05). HGF increased the hepatic gene expression of tumor necrosis factor-alpha compared with controls (p<.05). Serum IGF-I decreased in rats receiving HGF 1, 2, and 5 days after burn, whereas liver IGF-I concentrations were higher on days 1 and 7 after burn compared with controls (p<.05). Hepatic protein concentrations were higher in the HGF group compared with controls on postburn days 1, 2, and 7, with a concomitant increase in total liver weight (p<.05). HGF exerted a strong mitogenic effect on hepatocytes 1 and 2 days after thermal injury compared with controls (p<.05).

CONCLUSIONS

These findings suggest that HGF modulates the acute-phase response in vivo after burn and causes changes in liver morphology.

Insulinlike growth factor I plus insulinlike growth factor binding protein 3 attenuates the proinflammatory acute phase response in severely burned children

OBJECTIVE

To determine the effect of insulinlike growth factor I (IGF-I) in combination with its principal binding protein (IGFBP-3) on the hepatic acute phase response in severely burned children.

SUMMARY BACKGROUND DATA

The hepatic acute phase response is a cascade of events initiated to restore homeostasis after trauma. A prolonged response, however, may contribute to multiple organ failure, hypermetabolism, complications, and death.

METHODS

Twenty-two children with a mean total body surface area (TBSA) burn of 57 +/- 3% were given a continuous infusion of 1 to 4 mg/kg/day IGF-I/BP-3 for 5 days after wound excision and grafting. Eight children with a TBSA burn of 54 +/- 4% were given saline as controls. Before and 5 days after excision and grafting, blood samples were taken for serum hepatic constitutive protein, acute phase protein, and proinflammatory cytokine analysis.

RESULTS

Serum IGF-I levels in burned children given the IGF-I/BP-3 complex increased from 113 +/- 15 to 458 +/- 40 ng/mL and IGFBP-3 levels increased from 1.8 +/- 0.2 to 3.1 +/- 0.3 ng/mL. Levels of serum constitutive hepatic proteins (prealbumin, retinol-binding protein, and transferrin) increased with IGF-I/BP-3, whereas levels of type I acute phase proteins (C-reactive protein, alpha1-acid glycoprotein, and complement C-3) decreased when compared with controls. The complex had no effect on type II acute phase proteins. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) levels decreased with IGF-I/BP-3 compared with controls, with no effect on interleukin-6.

CONCLUSION

Severely burned children receiving IGF-I/BP-3 showed a decrease in IL-1beta and TNF-alpha followed by a decrease in type I acute phase proteins that was associated with a concomitant increase in constitutive hepatic proteins. Attenuating the proinflammatory acute phase with IGF-1/BP-3 response may prevent multiple organ failure and improve clinical outcomes after thermal injury without any detectable adverse side effects.

Time- and dose-related interactions between glucocorticoid and cyclic adenosine 3',5'-monophosphate on CCAAT/enhancer-binding protein-dependent insulin-like growth factor I expression by osteoblasts

Glucocorticoid has complex effects on osteoblasts. Several of these changes appear to be related to steroid concentration, duration of exposure, or specific effects on growth factor expression or activity within bone. One important bone growth factor, insulin-like growth factor I (IGF-I), is induced in osteoblasts by hormones such as PGE2 that increase intracellular cAMP levels. In this way, PGE2 activates transcription factor CCAAT/enhancer-binding protein-delta (C/EBPdelta) and enhances its binding to a specific control element found in exon 1 in the IGF-I gene. Our current studies show that preexposure to glucocorticoid enhanced C/EBPdelta and C/EBPbeta expression by osteoblasts and thereby potentiated IGF-I gene promoter activation in response to PGE2. Importantly, this directly contrasts with inhibitory effects on IGF-I expression that result from sustained or pharmacologically high levels of glucocorticoid exposure. Consistent with the stimulatory effect of IGF-I on bone protein synthesis, pretreatment with glucocorticoid sensitized osteoblasts to PGE2, and in this context significantly enhanced new collagen and noncollagen protein synthesis. Therefore, pharmacological levels of glucocorticoid may reduce IGF-I expression by osteoblasts and cause osteopenic disease, whereas physiological transient increases in glucocorticoid may permit or amplify the effectiveness of hormones that regulate skeletal tissue integrity. These events appear to converge on the important role of C/EBPdelta and C/EBPbeta on IGF-I expression by osteoblasts.

Increased expression of insulin-like growth factor-I in serum and liver after recombinant human growth hormone administration in thermally injured rats

BACKGROUND

Recombinant human growth hormone (rhGH) has been shown to modulate the hypermetabolic response and the hepatic acute-phase response after thermal injury. In vitro studies, however, demonstrated that rhGH activates insulin-like growth factor-I (IGF-I) gene transcription and production, suggesting that rhGH may exert some of its effects indirectly through IGF-I stimulation. The purpose of this study was to determine the effects of rhGH on serum and hepatic IGF-I in thermally injured rats.

METHODS

Sprague-Dawley rats (56 males) receiving a 60% TBSA third-degree scald burn were randomly divided to receive either rhGH (2.5 mg/kg/day im) or saline (control). Rats were sacrificed on postburn days 1, 2, 5, and 7 and serum IGF-I, hepatic IGF-I mRNA, and IGF-I protein concentration were measured. The physiologic response to changes in IGF-I levels was evaluated by measuring hepatocyte proliferation, total liver protein concentration, and muscle dry/wet weights.

RESULTS

Serum IGF-I was increased from postburn day 1 through day 7 in rats receiving rhGH compared to controls (P < 0.05). Hepatic IGF-I mRNA and IGF-I protein expression were increased from day 1 to 7 after burn in animals receiving rhGH when compared to controls (P < 0.05). Recombinant hGH increased hepatocyte proliferation at 5 days and total liver protein concentration at 5 and 7 days postburn compared to controls (P < 0.05). Muscle dry/wet weights increased in rats receiving rhGH at 7 days after burn compared to controls (P < 0.05).

SUMMARY

Liver and serum IGF-I levels decreased after a thermal injury. Recombinant hGH attenuated this decrease by stimulating hepatic IGF-I expression. Increases in IGF-I were associated with increases in hepatocyte proliferation and protein concentration in liver and muscle.

CONCLUSION

We suggest that rhGH modulates the hypermetabolic response through IGF-I stimulation in the hepatic parenchyma.

Recombinant human growth hormone alters acute phase reactant proteins, cytokine expression, and liver morphology in burned rats

BACKGROUND

The effects of exogenous recombinant human growth hormone (rhGH) on hepatic acute phase reactant proteins, cytokine expression, and liver morphology were studied in thermally injured rats to define whether rhGH alters the acute phase response.

MATERIALS AND METHODS

Sprague-Dawley rats (56 males) receiving a 60% TBSA third-degree scald burn were randomly divided into two groups to receive either 2.5 mg/kg/day sc rhGH or saline. Rats were sacrificed on Postburn Days 1, 2, 5, and 7. Serum acute phase reactant proteins and cytokines TNF-alpha, IL-1alpha, IL-1beta, and IL-6 were measured. Hepatocyte proliferation, hepatic cytokine gene expression, and liver protein concentrations were determined.

RESULTS

Recombinant hGH increased serum albumin on Days 5 and 7 after burn (P < 0.05). Serum haptoglobin and alpha1-acid glycoprotein levels decreased at 2, 5, and 7 days after burn compared to saline (P < 0.05). In rats treated with rhGH, serum IL-1beta decreased 1 day postburn, while serum TNF-alpha increased 5 days after burn compared to saline (P < 0.05). Serum IL-6 and IL-1alpha did not change. Hepatic RNA levels for TNF-alpha were significantly elevated on Day 1 postburn compared to saline (P < 0. 05). Hepatic protein content increased on Days 2, 5, and 7 postburn compared to saline (P < 0.05). Hepatocyte proliferation in rhGH-treated rats increased on Day 5 after burn (P < 0.05).

CONCLUSION

Data indicate that rhGH alters the hepatic acute phase response by decreasing type I acute phase proteins and modulating IL-1-like cytokine expression. These changes are associated with increased hepatocyte mitosis and serum and total liver protein concentrations.

Function of cis-acting elements in human alcohol dehydrogenase 4 (ADH4) promoter and role of C/EBP proteins in gene expression

The ADH4 gene, which encodes human pi-alcohol dehydrogenase, is expressed in a tissue-specific manner, with the highest level in liver and lower levels in the gastrointestinal tract. We examined the location and function of the cis-acting elements that regulate ADH4 transcription. Liver contains proteins that bound to seven sites in the proximal promoter (from bp -387 to bp +17). Proteins from other tissues bound to subsets of these sites and to two additional sites, one of which is a negative cis-acting element. Members of two important transcription factor families, C/EBP and AP-1, bound to several sites in this promoter. The proximal ADH4 promoter functioned in a hepatoma cell line (H4IIE-C3) and a kidney cell line (CV-1). Coexpression of members of the C/EBP family strongly enhanced promoter activity, which can in part explain the high level of expression of ADH4 in liver. At one site that can be bound by both C/EBP and c-Jun, a mutation that abolished binding by C/EBP but not by c-Jun decreased promoter activity in both cell lines. This mutation had a stronger effect in the context of a longer promoter, suggesting interaction among cis-acting elements.