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J Perren Cobb

Publications and source records attributed to J Perren Cobb.

At least 19 recordsLinked to original sources
PubMed2006

TAT-BH4 and TAT-Bcl-xL peptides protect against sepsis-induced lymphocyte apoptosis in vivo.

Apoptosis is a key pathogenic mechanism in sepsis that induces extensive death of lymphocytes and dendritic cells, thereby contributing to the immunosuppression that characterizes the septic disorder. Numerous animal studies indicate that prevention of apoptosis in sepsis improves survival and may represent a potential therapy for this highly lethal disorder. Recently, novel cell-penetrating peptide constructs such as HIV-1 TAT basic domain and related peptides have been developed to deliver bioactive cargoes and peptides into cells. In the present study, we investigated the effects of sepsis-induced apoptosis in Bcl-x(L) transgenic mice and in wild-type mice treated with an antiapoptotic TAT-Bcl-x(L) fusion protein and TAT-BH4 peptide. Lymphocytes from Bcl-x(L) transgenic mice were resistant to sepsis-induced apoptosis, and these mice had a approximately 3-fold improvement in survival. TAT-Bcl-x(L) and TAT-BH4 prevented Escherichia coli-induced human lymphocyte apoptosis ex vivo and markedly decreased lymphocyte apoptosis in an in vivo mouse model of sepsis. In conclusion, TAT-conjugated antiapoptotic Bcl-2-like peptides may offer a novel therapy to prevent apoptosis in sepsis and improve survival.

Animals↗
PubMed2006

Splenic CD4+ T cells have a distinct transcriptional response six hours after the onset of sepsis.

BACKGROUND: In animal and human autopsy studies of sepsis, CD4+ splenocytes either undergo apoptosis or are polarized to the Th2 effector subtype. In mice, these changes occur within 24 hours of the onset of sepsis. Preventing the loss of CD4+ T cells and the Th2-polarization of CD4+ T cells provides a significant survival advantage in mouse models of sepsis. The molecular mechanism(s) for the phenotypic changes of splenic CD4+ T cells in sepsis are not well understood. STUDY DESIGN: CD4+ splenocytes were enriched by negative selection from disaggregated spleens of septic and sham-operated mice at 6 and 24 hours after surgery. Phenotypic analysis using cell surface markers (CD25, CD44, CD62L, CD69), cytokine secretion in response to CD3/CD28 coligation, and whole genome microarray gene expression profiles were obtained for these cells. RESULTS: Consistent with previous reports, sepsis induced a progressive decrease in the number of CD4+ splenocytes and a time-dependent alteration in CD4+ T-cell phenotype. At 6 hours, when no differences in cell number or surface marker expression were observed, significant alterations in RNA abundance were measured for 498 probe sets. Ontologic classification of these genes indicated changes in cellular physiology. Pathway analysis indicated that T-cell receptor signaling and mitogen-activated protein kinase signaling were significantly altered by sepsis. CONCLUSIONS: These data demonstrated a sepsis-specific transcriptional program that precedes sepsis-induced phenotypic changes in CD4+ splenocytes.

Animals↗
PubMed2006

Temporal changes in mouse aortic wall gene expression during the development of elastase-induced abdominal aortic aneurysms.

OBJECTIVE: To characterize temporal changes in mouse aortic wall gene expression associated with the development of experimental abdominal aortic aneurysms. METHODS: C57BL/6 mice underwent transient perfusion of the abdominal aorta with either elastase (n = 61) or heat-inactivated elastase as a control (n = 68). Triplicate samples of radiolabeled aortic wall complementary DNA were prepared at intervals of 0, 3, 7, 10, and 14 days, followed by hybridization to nylon microarrays (1181 genes). Autoradiographic intensity data were normalized by conversion to z scores, and differences in gene expression were defined by two-tailed z tests at a significance threshold of P < .01. RESULTS: Elastase perfusion caused a progressive increase in aortic diameter up to 14 days accompanied by transmural inflammation and destructive remodeling of the elastic media. No aneurysms occurred in the control group. Compared with healthy aorta, 336 genes exhibited significant alterations during at least 1 interval after elastase perfusion (135 at more than 1 interval and 14 at all intervals), with pronounced increases for interleukin 6, cyclin E2, interleukin 1beta, osteopontin, CD14/lipopolysaccharide receptor, P-selectin glycoprotein ligand 1, and gelatinase B/matrix metalloproteinase 9 (all >20-fold on day 3). Sixty-two genes exhibited synchronous alterations in the elastase and control groups, thus suggesting a nonspecific response. By direct comparisons between the elastase and control groups, there were 384 genes with significant differences in expression for at least 1 interval after aortic perfusion, including 234 with differential upregulation (eg, p44MAPK/ERK1, osteopontin, heat shock protein 84, hypoxia-inducible factor 1alpha, apolipoprotein E, monocyte chemotactic protein 3, MIG (monokine induced by gamma interferon), and interleukin 2 receptor gamma) and 163 with differential downregulation (eg, prothrombin, granzyme B, ataxia telangiectasia mutated, and interleukin-converting enzyme). CONCLUSIONS: Development of elastase-induced abdominal aortic aneurysms in mice is accompanied by altered aortic wall expression of genes associated with acute and chronic inflammation, matrix degradation, and vascular tissue remodeling. Knowledge of these alterations will facilitate further studies on the functional molecular mechanisms that underlie aneurysmal degeneration.

Animals↗
PubMed2005

Commonality and differences in leukocyte gene expression patterns among three models of inflammation and injury.

The aim of this study was to compare gene expression profiles of leukocytes from blood (white blood cells; WBCs) and spleen harvested at an early time point after injury or sham injury in mice subjected to trauma/hemorrhage, burn injury, or lipopolysaccharide (LPS) infusion at three experimental sites. Groups of injured or LPS-infused animals and sham controls were killed at 2 h after injury and resuscitation, blood and spleen were harvested, and leukocyte populations were recovered after erythrocyte lysis. RNA was extracted from postlysis leukocyte populations. Complementary RNA was synthesized from each RNA sample and hybridized to microarrays. A large number (500-1,400) of genes were differentially expressed at the 2-h time point in injured or LPS-infused vs. sham animals. Thirteen of the differentially expressed genes in blood, and 46 in the spleen, were upregulated or downregulated in common among all three animal models and may represent a common, early transcriptional response to systemic inflammation from a variety of causes. The majority of these genes could be assigned to pathways involved in the immune response and cell death. The up- or downregulation of a cohort of 23 of these genes was validated by RT-PCR. This large-scale microarray analysis shows that, at the 2-h time point, there is marked alteration in leukocyte gene expression in three animal models of injury and inflammation. Although there is some commonality among the models, the majority of the differentially expressed genes appear to be uniquely associated with the type of injury and/or the inflammatory stimulus.

Animals↗
PubMed2005

Complement-induced regulatory T cells suppress T-cell responses but allow for dendritic-cell maturation.

Concurrent activation of the T-cell receptor (TCR) and complement regulator CD46 on human CD4+ T lymphocytes induces Tr1-like regulatory T cells that suppress through IL-10 secretion bystander T-cell proliferation. Here we show that, despite their IL-10 production, CD46-induced T-regulatory T cells (Tregs) do not suppress the activation/maturation of dendritic cells (DCs). DC maturation by complement/CD46-induced Tregs is mediated through simultaneous secretion of GM-CSF and soluble CD40L, factors favoring DC differentiation and reversing inhibitory effects of IL-10. Thus, CD46-induced Tregs produce a distinct cytokine profile that inhibits T-cell responses but leaves DC activation unimpaired. Such "DC-sparing" Tregs could be desirable at host/environment interfaces such as the gastrointestinal tract where their specific cytokine profile provides a mechanism that ensures unresponsiveness to commensal bacteria while maintaining reactivity to invading pathogens.

Antigens, CD↗
PubMed2005

A network-based analysis of systemic inflammation in humans.

Oligonucleotide and complementary DNA microarrays are being used to subclassify histologically similar tumours, monitor disease progress, and individualize treatment regimens. However, extracting new biological insight from high-throughput genomic studies of human diseases is a challenge, limited by difficulties in recognizing and evaluating relevant biological processes from huge quantities of experimental data. Here we present a structured network knowledge-base approach to analyse genome-wide transcriptional responses in the context of known functional interrelationships among proteins, small molecules and phenotypes. This approach was used to analyse changes in blood leukocyte gene expression patterns in human subjects receiving an inflammatory stimulus (bacterial endotoxin). We explore the known genome-wide interaction network to identify significant functional modules perturbed in response to this stimulus. Our analysis reveals that the human blood leukocyte response to acute systemic inflammation includes the transient dysregulation of leukocyte bioenergetics and modulation of translational machinery. These findings provide insight into the regulation of global leukocyte activities as they relate to innate immune system tolerance and increased susceptibility to infection in humans.

Acute Disease↗
PubMed2005

DAP12 (KARAP) amplifies inflammation and increases mortality from endotoxemia and septic peritonitis.

DAP12 (KARAP) is a transmembrane signaling adaptor for a family of innate immunoreceptors that have been shown to activate granulocytes and monocytes/macrophages, amplifying production of inflammatory cytokines. Contrasting with these data, recent studies suggest that DAP12 signaling has an inhibitory role in the macrophage response to microbial products (Hamerman, J.A., N.K. Tchao, C.A. Lowell, and L.L. Lanier. 2005. Nat. Immunol. 6:579-586). To determine the in vivo role for DAP12 signaling in inflammation, we measured the response of wild-type (WT) and DAP12-/- mice to septic shock. We show that DAP12-/- mice have improved survival from both endotoxemia and cecal ligation and puncture-induced septic shock. As compared with WT mice, DAP12-/- mice have decreased plasma cytokine levels and a decreased acute phase response during sepsis, but no defect in the recruitment of cells or bacterial control. In cells isolated after sepsis and stimulated ex vivo, DAP12 signaling augments lipopolysaccharide-mediated cytokine production. These data demonstrate that, during sepsis, DAP12 signaling augments the response to microbial products, amplifying inflammation and contributing to mortality.

Acute-Phase Reaction↗
PubMed2005

That which does not kill you makes you stronger: a molecular mechanism for preconditioning.

Preconditioning by sublethal stress can protect a cell from subsequent injury and apoptosis through a mechanism that has been unclear. Many such stresses stimulate the formation of stress granules: transient cytoplasmic foci that contain heat shock protein as well as translationally stalled mRNA and various mRNA-binding proteins. Recent research suggests that sequestration in stress granules of TRAF2, an adaptor protein that is required for tumor necrosis factor receptor 1 signaling, may underlie preconditioning by sublethal stresses.

Animals↗
PubMed2005

Application of genome-wide expression analysis to human health and disease.

The application of genome-wide expression analysis to a large-scale, multicentered program in critically ill patients poses a number of theoretical and technical challenges. We describe here an analytical and organizational approach to a systematic evaluation of the variance associated with genome-wide expression analysis specifically tailored to study human disease. We analyzed sources of variance in genome-wide expression analyses performed with commercial oligonucleotide arrays. In addition, variance in gene expression in human blood leukocytes caused by repeated sampling in the same subject, among different healthy subjects, among different leukocyte subpopulations, and the effect of traumatic injury, were also explored. We report that analytical variance caused by sample processing was acceptably small. Blood leukocyte gene expression in the same individual over a 24-h period was remarkably constant. In contrast, genome-wide expression varied significantly among different subjects and leukocyte subpopulations. Expectedly, traumatic injury induced dramatic changes in apparent gene expression that were greater in magnitude than the analytical noise and interindividual variance. We demonstrate that the development of a nation-wide program for gene expression analysis with careful attention to analytical details can reduce the variance in the clinical setting to a level where patterns of gene expression are informative among different healthy human subjects, and can be studied with confidence in human disease.

Cluster Analysis↗
PubMed2005

Global gene expression in neuroendocrine tumors from patients with the MEN1 syndrome.

BACKGROUND: Multiple Endocrine Neoplasia type 1 (MEN1, OMIM 131100) is an autosomal dominant disorder characterized by endocrine tumors of the parathyroids, pancreatic islets and pituitary. The disease is caused by the functional loss of the tumor suppressor protein menin, coded by the MEN1 gene. The protein sequence has no significant homology to known consensus motifs. In vitro studies have shown menin binding to JunD, Pem, Smad3, NF-kappaB, nm23H1, and RPA2 proteins. However, none of these binding studies have led to a convincing theory of how loss-of-menin leads to neoplasia. RESULTS: Global gene expression studies on eight neuroendocrine tumors from MEN1 patients and 4 normal islet controls was performed utilizing Affymetrix U95Av2 chips. Overall hierarchical clustering placed all tumors in one group separate from the group of normal islets. Within the group of tumors, those of the same type were mostly clustered together. The clustering analysis also revealed 19 apoptosis-related genes that were under-expressed in the group of tumors. There were 193 genes that were increased/decreased by at least 2-fold in the tumors relative to the normal islets and that had a t-test significance value of p < or = 0.005. Forty-five of these genes were increased and 148 were decreased in the tumors relative to the controls. One hundred and four of the genes could be classified as being involved in cell growth, cell death, or signal transduction. The results from 11 genes were selected for validation by quantitative RT-PCR. The average correlation coefficient was 0.655 (range 0.235-0.964). CONCLUSION: This is the first analysis of global gene expression in MEN1-associated neuroendocrine tumors. Many genes were identified which were differentially expressed in neuroendocrine tumors arising in patients with the MEN1 syndrome, as compared with normal human islet cells. The expression of a group of apoptosis-related genes was significantly suppressed, suggesting that these genes may play crucial roles in tumorigenesis in this syndrome. We identified a number of genes which are attractive candidates for further investigation into the mechanisms by which menin loss causes tumors in pancreatic islets. Of particular interest are: FGF9 which may stimulate the growth of prostate cancer, brain cancer and endometrium; and IER3 (IEX-1), PHLDA2 (TSS3), IAPP (amylin), and SST, all of which may play roles in apoptosis.

Adult↗
PubMed2004

Whole blood and leukocyte RNA isolation for gene expression analyses.

The analysis of gene expression data in clinical medicine has been plagued by the lack of a critical evaluation of accepted methodologies for the collection, processing, and labeling of RNA. In the present report, the reliability of two commonly used techniques to isolate RNA from whole blood or its leukocyte compartment was compared by examining their reproducibility, variance, and signal-to-noise ratios. Whole blood was obtained from healthy subjects and was either untreated or stimulated ex vivo with Staphylococcus enterotoxin B (SEB). Blood samples were also obtained from trauma patients but were not stimulated with SEB ex vivo. Total RNA was isolated from whole blood with the PAXgene proprietary blood collection system or from isolated leukocytes. Biotin-labeled cRNA was hybridized to Affymetrix GeneChips. The Pearson correlation coefficient for gene expression measurements in replicates from healthy subjects with both techniques was excellent, exceeding 0.985. Unsupervised analyses, including hierarchical cluster analysis, however, revealed that the RNA isolation method resulted in greater differences in gene expression than stimulation with SEB or among different trauma patients. The intraclass correlation, a measure of signal-to-noise ratio, of the difference between SEB-stimulated and unstimulated blood from healthy subjects was significantly higher in leukocyte-derived samples than in whole blood: 0.75 vs. 0.46 (P = 0.002). At the P < 0.001 level of significance, twice as many probe sets discriminated between SEB-stimulated and unstimulated blood with leukocyte isolation than with PAXgene. The findings suggest that the method of RNA isolation from whole blood is a critical variable in the design of clinical studies using microarray analyses.

Adolescent↗
PubMed2004

Injury research in the genomic era.

With the development of trauma systems, improved resuscitation, and organ system support, survival after severe injury is common, but is often complicated by nosocomial infection and organ failure. These complications are costly, and can lead to death or disability. Although much is known about the pathophysiology of post-traumatic nosocomial infection and organ failure, findings have been limited by our ability to generate and analyse large amounts of experimental and observational data. However, technological advances in nucleic acid and protein analysis, coupled with increased computational capacity, provide an opportunity to characterise the determinants of and the responses to injury and sepsis on a genome-wide scale. New large-scale collaborative efforts aim to investigate the genome for variation (gene polymorphisms), characterise multiple levels of the biological response to injury (transcriptome and proteome), and relate these to clinical phenotypes. In this article, we summarise recent findings and explore where promising new technologies might have the greatest potential for increasing our knowledge. It will now be important to determine how these recent technological advances can be used and integrated with our existing approaches, to reduce death, disability, and the economic consequences of trauma.

Computational Biology↗
PubMed2004

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.

Animals↗
PubMed2004

Sequence makes a difference: paradoxical effects of stress in vivo.

In vitro studies have shown that induction of heat shock before an inflammatory stimulus is cytoprotective, whereas induction of heat shock after an inflammatory stimulus can lead to apoptosis (the "heat shock paradox"). We sought to determine whether induction of the heat shock response in vivo caused similar, order-dependent effects on survival, and if so, by what mechanism. ND4 and C57BL/6 mice were used to calibrate the response to hyperthermia at 41.5 degrees C via induction of inducible heat shock protein 70. Sequences of heat shock and septic stresses were studied in murine models of hyperthermia (41.5 degrees C for 20 min) and cecal ligation and puncture (CLP), respectively. Previous heat shock to 41.5 degrees C did not protect CLP mice when compared with control CLP animals heated to 37 degrees C, but heat shock increased mortality when activated after CLP compared with controls. This effect of heat shock on CLP mortality was strain independent, and did not involve alterations in CLP-induced thymus, spleen, or intestinal apoptosis. We conclude that the heat shock paradox can occur in vitro and in vivo, and that the negative effects of heat shock on survival after CLP appeared to be strain independent. Furthermore, the stress of general anesthesia and warming also altered CLP mortality unexpectedly. The cellular mechanisms responsible for these "stressor" paradoxes in vivo are not known, but do not involve altered sepsis-induced apoptosis.

Animals↗