Characterisation of the biological response of Saccharomyces cerevisiae to the loss of an allele of the eukaryotic initiation factor 4A.

The translation initiation machinery is emerging as an important target for therapeutic intervention, with potential in the treatment of cancer, viral infections, and muscle wasting. Amongst the targets for pharmacological control of translation initiation is the eukaryotic initiation factor 4A (eIF4A), an RNA helicase that is essential for cap-dependent translation initiation. We set out to explore the system-wide impact of a reduction of functional eIF4A. To this end, we investigated the effect of deletion of TIF1, one of the duplicate genes that produce eIF4A in yeast, through synthetic genetic array interactions and system-wide changes in GFP-tagged protein abundances. We show that there is a biological response to deletion of the TIF1 gene that extends through the proteostasis network. Effects of the deletion are apparent in processes as distributed as chromatin remodelling, ribosome biogenesis, amino acid metabolism, and protein trafficking. The results from this study identify protein complexes and pathways that will make ideal targets for combination therapies with eIF4A inhibitors.

Identification of Targeting Peptides for Mucosal Delivery in Sheep and Mice.

In this study we identified and characterized a novel cyclic peptide that facilitates the rapid transportation of conjugated molecules across the epithelial layer of the small intestine. The peptide was initially selected from phage display libraries using a large animal experimental model, which employed consecutive in vitro and in vivo panning. The procedure was designed to enrich for peptides that facilitated transcytosis across the intestinal epithelium into the intestinal afferent lymphatic system. A small set of peptides was repeatedly isolated using this selection method; however, the cyclic nonamer CTANSSAQC, 13C, dominated. The activity of the putative targeting peptide 13C was then verified using a mouse model. These experiments showed that the 13C peptide as well as macromolecules conjugated to it were rapidly transported across the intestinal mucosa into distinct subsets of epithelial cells and CD11c+ cells located in the lamina propria and Peyer's Patches. Significant amounts of intact protein could be delivered into the systemic circulation after rectal and nasal application. Thus, peptide 13C is regarded as an attractive carrier candidate for mucosal delivery of large molecules. The preferential targeting to distinct intestinal cells may be utilized to deliver active biological drugs for the effective control of diseases of the gut.

Kinetochore genes are required to fully activate secretory pathway expansion in S. cerevisiae under induced ER stress.

Basal ER stress occurs when proteins misfold in normal physiological conditions and are corrected by the unfolded protein response (UPR). Elevated ER stress occurs when misfolding is refractory as found in numerous diseases such as atherosclerosis, Type II diabetes and some cancers. In elevated ER stress it is unclear whether cells utilise the same or different networks of genes as in basal levels of ER stress. To probe this question, we used secretory pathway reporters Yip3p-GFP, Erv29p-GFP, Orm2p-GFP and UPREpr-GFP placed on the yeast deletion mutant array (DMA) genetic background. The reporter's expression levels, measured by automated microscopy, at basal versus elevated ER stress induced by the over-expression of CPY* were compared. A novel group of kinetochore genes (CTF19 complex) were found to be uniquely required for full induction of all four ER stress reporters in elevated stress. A follow-up reporter screen was developed by mating the ctf19Δ kinetochore gene deletion strain into the genome-wide XXXp-GFP tagged library then testing with over-expressed CPY*. This screen identified Bcy1p and Bfr1p as possible signalling points that down-regulate the UPR and secretory pathway when kinetochore proteins are absent under elevated stress conditions. Bfr1p appears to be a checkpoint that monitors the integrity of kinetochores at increased levels of ER stress. This study concludes that functional kinetochores are required for full activation of the secretory pathway in elevated ER stress and that the responses to basal and elevated levels of ER stress require different networks of genes.

Estrogen-provided cardiac protection following burn trauma is mediated through a reduction in mitochondria-derived DAMPs.

Mitochondria-derived danger-associated molecular patterns (DAMPs) play important roles in sterile inflammation after acute injuries. This study was designed to test the hypothesis that 17ß-estradiol protects the heart via suppressing myocardial mitochondrial DAMPs after burn injury using an animal model. Sprague-Dawley rats were given a third-degree scald burn comprising 40% total body surface area (TBSA). 17ß-Estradiol, 0.5 mg/kg, or control vehicle was administered subcutaneously 15 min following burn. The heart was harvested 24 h postburn. Estradiol showed significant inhibition on the productivity of H2O2 and oxidation of lipid molecules in the mitochondria. Estradiol increased mitochondrial antioxidant defense via enhancing the activities and expression of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Estradiol also protected mitochondrial respiratory function and structural integrity. In parallel, estradiol remarkably decreased burn-induced release of mitochondrial cytochrome c and mitochondrial DNA (mtDNA) into cytoplasm. Further, estradiol inhibited myocardial apoptosis, shown by its suppression on DNA laddering and downregulation of caspase 1 and caspase 3. Estradiol's anti-inflammatory effect was demonstrated by reduction in systemic and cardiac cytokines (TNF-α, IL-1ß, and IL-6), decrease in NF-κB activation, and attenuation of the expression of inflammasome component ASC in the heart of burned rats. Estradiol-provided cardiac protection was shown by reduction in myocardial injury marker troponin-I, amendment of heart morphology, and improvement of cardiac contractility after burn injury. Together, these data suggest that postburn administration of 17ß-estradiol protects the heart via an effective control over the generation of mitochondrial DAMPs (mtROS, cytochrome c, and mtDNA) that incite cardiac apoptosis and inflammation.

Networks of genes modulating the pleiotropic drug response in Saccharomyces cerevisiae.

The pleiotropic drug response (PDR) or multidrug resistance (MDR) are cellular defence mechanisms present in all species to deal with potential toxicity from environmental small molecule toxins or bioactives. The rapid induction of MDR by xenobiotics in mammalian cells and PDR in budding yeast (S. cerevisiae) has been well studied but how pathway specificity is achieved across different structural classes of xenobiotics is not well understood. As a novel approach to this problem we investigated the genome-wide network of genes modulating the yeast PDR. Fluorescently-tagged ABC pumps Pdr5p-GFP and Yor1p-GFP were used as real-time reporters for the Pdr1p/Pdr3p controlled response. Using the yeast non-essential gene deletion set fifty-four gene deletions that suppressed up-regulation of reporter fluorescence to the cell surface in the presence of atorvastatin were identified by high content confocal automated microscopy. Secondary validation using spot dilution assays to known PDR substrates and Western blot assays of Pdr5p expression confirmed 26 genes able to modulate the PDR phenotype. By analysis of network connectivity, an additional 10 genes that fell below the primary screen cut-off were predicted to be involved in PDR and confirmed as above. The PDR modulating genes taken together were enriched in signalling (Rho-GTPase, MAPK), Mediator complexes, and chromatin modification (subunits of ADA and SAGA complexes). Many of the gene deletions cause extra sensitivity in Δpdr1Δpdr3 strains strongly suggesting that there are alternative pathways to upregulate PDR, independently of Pdr1p/Pdr3p. We present here the first high-content microscopy screening for PDR modulators, and identify genes that are previously unsuspected regulators of PDR apparently contributing via network interactions.

Characterizing the laulimalide-peloruside binding site using site-directed mutagenesis of TUB2 in S. cerevisiae.

Baker's yeast, Saccharomyces cerevisiae, has significant sequence conservation with a core subset of mammalian proteins and can serve as a model for disease processes. The aim of this study was to determine whether yeast could be used as a model system to identify new agents that interact with the laulimalide-peloruside binding site on ß-tubulin. Agents that bind to this site cause stabilization of microtubules and interfere with cell division. Based on the location of the proposed laulimalide-peloruside binding site and of previously identified mutations shown to cause resistance in mammalian cells, we made the corresponding mutations in yeast and tested whether they conferred resistance to laulimalide and peloruside. Mutations A296T and R306H, which cause 6-fold and 40-fold increased resistance in human 1A9 ovarian carcinoma cells, respectively, also led to resistance in yeast to these compounds. Similarly, other mutations led to resistance or, in one case, increased sensitivity. Thus, we conclude that yeast is an appropriate model to screen for small molecule drugs that may be efficacious in cancer therapy in humans through the newly characterised laulimalide-peloruside binding site.

Deficiency in Heat Shock Factor 1 (HSF-1) Expression Exacerbates Sepsis-induced Inflammation and Cardiac Dysfunction.

In the present study, we investigated whether absence of heat shock factor 1 (HSF-1) and inability to increase myocardial expression of heat shock proteins alter septic responses of inflammatory cytokines and myocardial contractility. HSF-1 knockout (hsf -/-) mice and wild type litter mates underwent a sterile (lipopolysaccharide; LPS) or infectious (Streptococcus pneumoniae or Klebsiella pneumoniae) septic challenge. Production of cytokines, TNF, IL-1ß, IL-6 and IL-10, in the blood and from cardiomyocytes was exaggerated in the hsf -/- mice compared to responses measured in wild type mice given an identical septic challenge. This enhanced compartmentalized myocardial inflammation was associated with significantly decreased cardiac contraction and diminished relaxation in the hsf -/- mice. However, lacking HSF-1 expression did not affect intracellular calcium and sodium responses in cardiomyocytes isolated from septic challenged mice, suggesting that ion loading was not a major or sustaining cause of the greater myocardial contractile defects in hsf -/- mice. In conclusion, our data indicated that HSF-1 and downstream heat shock proteins are essential components to support cardiac function in sepsis. Further studies are warranted to further define the precise mechanisms of HSF-1 mediated cardiac protection.

17ß-Estradiol reappropriates mass lost to the hypermetabolic state in thermally injured rats.

BACKGROUND: The hypermetabolic response to severe thermal injury is unlike any physiologic response seen in medicine. While some parallels can be drawn to shock and sepsis states, this response is typified by its intensity and duration. Our group has been interested in the myriad effects of estrogens after injury, specifically the ability of estrogens to reduce inflammatory responses. Given this, and the known link between severe inflammation and the hypermetabolic response, we examined the effects of a single dose of 17ß estradiol administered after a severe thermal injury in rats. METHODS: Twelve male Sprague-Dawley rats were subject to either a sham burn or a 40% total body surface area burn, followed by fluid resuscitation. Burned animals were divided into a vehicle and treatment group, with injections given 15 min after the injury. Animals were monitored for a period of 45 d, with markers of hypermetabolism (weight, fecal output, food intake, and serum insulin and glucose) measured daily. RESULTS: We identified a significant difference in daily measured weights between the burned groups. We observed a sparing of body mass during the acute phase lasting 2 wk after the injury and an improved recovery phase during the remainder of the study. Glucose and insulin levels during the first week of the study did not differ between the treatment groups. CONCLUSION: Estrogen may have a role in preserving body mass after severe thermal injury. Further studies are required to determine if this spared body mass composition.

The cellular target specificity of pateamine A.

The natural product pateamine A (pateamine) from the sponge Mycale hentscheli is active against a wide range of dividing cells and has been shown to inhibit the functions of the eukaryotic initiation factor 4A (eIF4A). We have identified that pateamine is additionally able to modulate the formation of actin filaments and microtubules in vitro but at higher concentrations than required for inhibition of eIF4A. Cell cycle analysis confirmed that actin and tubulin are not major mediators of the cellular activity of pateamine. The range of targets identified demonstrates the value of multiple approaches to determining the mode of action of biologically active compounds.

Sepsis-induced cardiac mitochondrial dysfunction involves altered mitochondrial-localization of tyrosine kinase Src and tyrosine phosphatase SHP2.

Our previous research demonstrated that sepsis produces mitochondrial dysfunction with increased mitochondrial oxidative stress in the heart. The present study investigated the role of mitochondria-localized signaling molecules, tyrosine kinase Src and tyrosine phosphatase SHP2, in sepsis-induced cardiac mitochondrial dysfunction using a rat pneumonia-related sepsis model. SD rats were given an intratracheal injection of Streptococcus pneumoniae, 4×10(6) CFU per rat, (or vehicle for shams); heart tissues were then harvested and subcellular fractions were prepared. By Western blot, we detected a gradual and significant decrease in Src and an increase in SHP2 in cardiac mitochondria within 24 hours post-inoculation. Furthermore, at 24 hours post-inoculation, sepsis caused a near 70% reduction in tyrosine phosphorylation of all cardiac mitochondrial proteins. Decreased tyrosine phosphorylation of certain mitochondrial structural proteins (porin, cyclophilin D and cytochrome C) and functional proteins (complex II subunit 30kD and complex I subunit NDUFB8) were evident in the hearts of septic rats. In vitro, pre-treatment of mitochondrial fractions with recombinant active Src kinase elevated OXPHOS complex I and II-III activity, whereas the effect of SHP2 phosphatase was opposite. Neither Src nor SHP2 affected complex IV and V activity under the same conditions. By immunoprecipitation, we showed that Src and SHP2 consistently interacted with complex I and III in the heart, suggesting that complex I and III contain putative substrates of Src and SHP2. In addition, in vitro treatment of mitochondrial fractions with active Src suppressed sepsis-associated mtROS production and protected aconitase activity, an indirect marker of mitochondrial oxidative stress. On the contrary, active SHP2 phosphatase overproduced mtROS and deactivated aconitase under the same in vitro conditions. In conclusion, our data suggest that changes in mitochondria-localized signaling molecules Src and SHP2 constitute a potential signaling pathway to affect mitochondrial dysfunction in the heart during sepsis.

Specific inhibition of mitochondrial oxidative stress suppresses inflammation and improves cardiac function in a rat pneumonia-related sepsis model.

Using a mitochondria-targeted vitamin E (Mito-Vit-E) in a rat pneumonia-related sepsis model, we examined the role of mitochondrial reactive oxygen species in sepsis-mediated myocardial inflammation and subsequent cardiac contractile dysfunction. Sepsis was produced in adult male Sprague-Dawley rats via intratracheal injection of S. pneumonia (4 × 10(6) colony formation units per rat). A single dose of Mito-Vit-E, vitamin E, or control vehicle, at 21.5 µmol/kg, was administered 30 min postinoculation. Blood was collected, and heart tissue was harvested at various time points. Mito-Vit-E in vivo distribution was confirmed by mass spectrometry. In cardiac mitochondria, Mito-Vit-E improved total antioxidant capacity and suppressed H(2)O(2) generation, whereas vitamin E offered little effect. In cytosol, both antioxidants decreased H(2)O(2) levels, but only vitamin E strengthened antioxidant capacity. Mito-Vit-E protected mitochondrial structure and function in the heart during sepsis, demonstrated by reduction in lipid and protein oxidation, preservation of mitochondrial membrane integrity, and recovery of respiratory function. While both Mito-Vit-E and vitamin E suppressed sepsis-induced peripheral and myocardial production of proinflammatory cytokines (tumor necrosis factor-α, interleukin-1ß, and interleukin-6), Mito-Vit-E exhibited significantly higher efficacy (P < 0.05). Stronger anti-inflammatory action of Mito-Vit-E was further shown by its near-complete inhibition of sepsis-induced myeloperoxidase accumulation in myocardium, suggesting its effect on neutrophil infiltration. Echocardiography analysis indicated that Mito-Vit-E ameliorated cardiac contractility of sepsis animals, shown by improved fractional shortening and ejection fraction. Together, our data suggest that targeted scavenging of mitochondrial reactive oxygen species protects mitochondrial function, attenuates tissue-level inflammation, and improves whole organ activities in the heart during sepsis.

Secretory pathway genes assessed by high-throughput microscopy and synthetic genetic array analysis.

We developed a procedure for automated confocal microscopy to image the effect of the non-essential yeast gene deletion set on the localisation of the plasma membrane GFP-labelled protein Mrh1p-GFP. To achieve this it was necessary to devise an expression system expressing Redstar2 RFP-fluorescence specifically in the nucleus, mCherry RFP at a lower intensity in the cytoplasm and Mrh1p-GFP in the plasma membrane. This fluorescence labelling scheme utilising specifically designed image analysis scripts allowed automated segmentation of the cells into sub-regions comprising nuclei, cytoplasm and cell-surface. From this high-throughput high content screening approach we were able to determine that gene deletions including emc1Δ, emc2Δ, emc3Δ, emc4Δ, emc5Δ and emc6Δ, caused intracellular mislocalisation at the ER of a plasma membrane protein Mrh1p-GFP. CPY processing patterns were unaffected in these mutants and collectively our data suggest a transport role for the EMC genes within the early secretory pathway. HAC1 is central to the unfolded protein response (UPR) and in its absence, i.e. the absence of UPR, emc1Δ-, emc3Δ-, emc4Δ-, emc5Δ-hac1Δ double mutants were specifically hypersensitive to ER-stress (tunicamycin) lending credence to the usefulness of the high content microscope screening for discovery of functional effects of single mutants.

Regulation of VEGF-induced endothelial cell migration by mitochondrial reactive oxygen species.

Endothelial migration is a crucial aspect of a variety of physiologic and pathologic conditions including atherosclerosis and vascular repair. Reactive oxygen species (ROS) function as second messengers during endothelial migration. Multiple intracellular sources of ROS are regulated by cellular context, external stimulus, and the microenvironment. However, the predominant source of ROS during endothelial cell (EC) migration and the mechanisms by which ROS regulate cell migration are incompletely understood. In this study, we tested the hypothesis that mitochondria-derived ROS (mtROS) regulate EC migration. In cultured human umbilical vein endothelial cells, VEGF increased mitochondrial metabolism, promoted mtROS production, and induced cell migration. Either the targeted mitochondrial delivery of the antioxidant, vitamin E (Mito-Vit-E), or the depletion of mitochondrial DNA abrogated VEGF-mediated mtROS production. Overexpression of mitochondrial catalase also inhibited VEGF-induced mitochondrial metabolism, Rac activation, and cell migration. Furthermore, these interventions suppressed VEGF-stimulated EC migration and blocked Rac1 activation in endothelial cells. Constitutively active Rac1 reversed Mito-Vit-E-induced inhibition of EC migration. Mito-Vit-E also attenuated carotid artery reendothelialization in vivo. These results provide strong evidence that mtROS regulate EC migration through Rac-1.

Investigation of the temperature stability of premarin intravenous using liquid chromatography-mass spectrometry.

Stability of Premarin(®)Intravenous was investigated in dry and reconstituted forms by monitoring major components in samples for a period of six months, using liquid chromatography-mass spectrometry. The components, largely comprising a series of estrogen and steroid hormone sulfates, were considered to be fairly stable (variation≤10%) for dry samples stored at room temperature and at 38°C (100°F) during the experimental time frame. However, significant variation, especially after 2 months of storage, was observed in reconstituted solutions. This variation was significantly larger for samples stored at elevated vs. room temperature. It was interesting to note that the concentration of equilenin sulfate increased over time, whereas that of other major components were seen to fluctuate and decrease. This phenomenon was partially explained by the conversion of equilin compounds into their corresponding equilenin forms, a phenomenon which was further investigated through a storage study with pure standard solutions and by tandem mass spectrometry.

Simultaneous quantification of four native estrogen hormones at trace levels in human cerebrospinal fluid using liquid chromatography-tandem mass spectrometry.

Estrogens are known to exhibit neuroprotective effects on the brain. Their importance in this regard and in others has been emphasized in many recent studies, which increases the need to develop reliable analytical methods for the measurement of estrogen hormones. A heart-cutting two-dimensional liquid chromatography separation method coupled with electrospray ionization-tandem mass spectrometry (ESI-MS/MS) has been developed for simultaneous measurement of four estrogens, including estriol (E3), estrone (E1), 17ß-estradiol (17ß-E2), and 17α-estradiol (17α-E2), in human cerebrospinal fluid (CSF). The method was based on liquid-liquid extraction and derivatization of estrogens with dansyl chloride to enhance the sensitivity of ESI-based detection in conjunction with tandem mass spectrometry. Dansylated estriol and estrone were separated in the first dimension by an amide-C18 column, while dansylated 17ß- and 17α-estradiol were resolved on the second dimension by two C18 columns (175 mm total length) connected in series. This is the first report of a method for simultaneous quantification of all four endogenous estrogen compounds in their dansylated form. The detection limits for E1, 17α-E2, 17ß-E2, and E3 were 19, 35, 26, and 61pg/mL, respectively. Due to matrix effects, validation and calibration was carried out in charcoal-stripped CSF. The precision and accuracy were more than 86% for the two E2 compounds and 79% for E1 and E3 while the extraction recovery ranged from 91% to 104%. The method was applied to measure estrogens obtained in a clinical setting, from the CSF of ischemic trauma patients. While 17ß-estradiol was present at a significant level in the CSF of some samples, other estrogens were present at lower levels or were undetectable.

Burn serum causes a CD14-dependent mitochondrial damage in primary cardiomyocytes.

Studies from animal models suggest that myocardial mitochondrial damage contributes to cardiac dysfunction after burn injury. In this report, we used an ex vivo model of primary cardiomyocyte culture to investigate the mechanisms of burn-induced mitochondrial impairment. Briefly, blood serum was collected from Sprague-Dawley (SD) rats subjected to 40% total body surface area burn and added (10% vol/vol) to primary cardiomyocytes prepared from SD rats. The effect of the burn serum on mitochondrial function and membrane integrity in the myocytes was analyzed. Exposure of myocytes to burn serum doubled the mitochondrial membrane damage measured by two independent assays. This treatment also significantly elevated mitochondrial oxidative stress, indicated by a more than 30% increase in lipid oxidation. Downregulation of mitochondrial antioxidant defense was also evident since the activities of the antioxidant enzymes superoxide dismutase and glutathione peroxidase were reduced by about 30% and 50%, respectively. Burn serum also induced deficiency of mitochondrial metabolism, indicated by a 30% decrease in the activity of cytochrome c oxidase. These mitochondrial dysfunctions appear to be generated by oxidative stress because burn serum induced a significant increase of mitochondrial oxygen species (mtROS) in cardiomyocytes, and pretreatment of cardiomyocytes with the antioxidant N-acetyl-cysteine prevented the mitochondrial damages induced by burn serum. Remarkably, the increase in mtROS was abolished by an antibody-mediated blockade of CD14. Furthermore, burn injury-induced mitochondrial damage in cardiomyocytes was prevented in CD14 knockout mice. Taken together, these data suggested that burn injury produces CD14-dependent mitochondrial damage via oxidative stress in myocardium.

Age-dependent differences of interleukin-6 activity in cardiac function after burn complicated by sepsis.

Interleukin (IL)-6 is a pleiotropic cytokine that is activated after acute injuries, and plays an important role during aging. We aim to define the role of IL-6 on myocardial dysfunction following a 40% total body surface area burn followed by late (7 days) Streptococcus pneumoniae sepsis (burn plus sepsis) in 2- and 14-month-old wild type and IL-6(-/-) mice. We measured global hemodynamic and cardiac contractile function with left ventricular pressure-volume analysis 24h after sepsis induction, and measured phosphorylated signal transducer and activator of transcription 3 (p-STAT-3), tumor necrosis factor (TNF)-alpha, and IL-1beta in the heart with Western blot analysis. We also measured mRNA expression of IL-6, TNF-alpha, and IL-1beta. Sham injured mice did not manifest any appreciable level of p-STAT-3 or functional deficiencies regardless of age or presence of the IL-6 gene. Burn plus sepsis injury was associated with a significant deterioration of global hemodynamic and cardiac contractile function in WT mice in both age groups. This dysfunction was attenuated by IL-6 deficiency at age 2 months, but accentuated at age 14 months. Aging was associated with an increase in mRNA expression of IL-6 (WT mice), TNF-alpha, and IL-1beta (all mice). At age 14 months, IL-6 deficient mice exhibited a greater TNF-alpha mRNA expression than the wild type mice. We conclude aging is associated with changed cytokine gene transcription, and burn plus sepsis injury further intensifies such gene responses. IL-6 deficiency does not abrogate STAT-3 phosphorylation and it may enhance expression of other inflammatory cytokines. The differential effects of IL-6 deficiency on the cardiac function in young and aging mice cannot be explained by cytokine gene expression alone, and require further studies.

Estrogen treatment following severe burn injury reduces brain inflammation and apoptotic signaling.

BACKGROUND: Patients with severe burn injury experience a rapid elevation in multiple circulating pro-inflammatory cytokines, with the levels correlating with both injury severity and outcome. Accumulations of these cytokines in animal models have been observed in remote organs, however data are lacking regarding early brain cytokine levels following burn injury, and the effects of estradiol on these levels. Using an experimental animal model, we studied the acute effects of a full-thickness third degree burn on brain levels of TNF-alpha, IL-1beta, and IL-6 and the protective effects of acute estrogen treatment on these levels. Additionally, the acute administration of estrogen on regulation of inflammatory and apoptotic events in the brain following severe burn injury were studied through measuring the levels of phospho-ERK, phospho-Akt, active caspase-3, and PARP cleavage in the placebo and estrogen treated groups. METHODS: In this study, 149 adult Sprague-Dawley male rats received 3rd degree 40% total body surface area (TBSA) burns. Fifteen minutes following burn injury, the animals received a subcutaneous injection of either placebo (n = 72) or 17 beta-estradiol (n = 72). Brains were harvested at 0.5, 1, 2, 4, 6, 8, 12, 18, and 24 hours after injury from the control (n = 5), placebo (n = 8/time point), and estrogen treated animals (n = 8/time point). The brain cytokine levels were measured using the ELISA method. In addition, we assessed the levels of phosphorylated-ERK, phosphorylated-Akt, active caspase-3, and the levels of cleaved PARP at the 24 hour time-point using Western blot analysis. RESULTS: In burned rats, 17 beta-estradiol significantly decreased the levels of brain tissue TNF-alpha (approximately 25%), IL-1beta (approximately 60%), and IL-6 (approximately 90%) when compared to the placebo group. In addition, we determined that in the estrogen-treated rats there was an increase in the levels of phospho-ERK (p < 0.01) and Akt (p < 0.05) at the 24 hour time-point, and that 17 beta-estradiol blocked the activation of caspase-3 (p < 0.01) and subsequent cleavage of PARP (p < 0.05). CONCLUSION: Following severe burn injury, estrogens decrease both brain inflammation and the activation of apoptosis, represented by an increase in the levels of phospho-Akt and inhibition of caspase-3 activation and PARP cleavage. Results from these studies will help further our understanding of how estrogens protect the brain following burn injury, and may provide a novel, safe, and effective clinical treatment to combat remote secondary burn injury in the brain and to preserve cognition.

Intraspecific epitopic variation in a carbohydrate antigen exposed on the surface of Trichostrongylus colubriformis infective L3 larvae.

The carbohydrate larval antigen, CarLA, is present on the exposed surface of all strongylid nematode infective L3 larvae tested, and antibodies against CarLA can promote rapid immune rejection of incoming Trichostrongylus colubriformis larvae in sheep. A library of ovine recombinant single chain Fv (scFv) antibody fragments, displayed on phage, was prepared from B cell mRNA of field-immune sheep. Phage displaying scFvs that bind to the surface of living exsheathed T. colubriformis L3 larvae were identified, and the majority of worm-binding scFvs recognized CarLA. Characterization of greater than 500 worm surface binding phage resulted in the identification of nine different anti-CarLA scFvs that recognized three distinct T. colubriformis CarLA epitopes based on blocking and additive ELISA. All anti-CarLA scFvs were specific to the T. colubriformis species of nematode. Each of the three scFv epitope classes displayed identical Western blot recognition patterns and recognized the exposed surface of living T. colubriformis exsheathed L3 larvae. Surprisingly, each of the anti-CarLA scFvs was able to bind to only a subset of worms. Double-labelling indirect immunofluorescence revealed that the three classes of anti-CarLA scFvs recognize distinct, non-overlapping, T. colubriformis sub-populations. These results demonstrate that individual T. colubriformis L3 larvae display only one of at least three distinct antigenic forms of CarLA on their surface at any given time, and suggest that antigenic variation within CarLA is likely a mechanism of immune evasion in strongylid nematodes.

Alterations in the cardiac inflammatory response to burn trauma in mice lacking a functional Toll-like receptor 4 gene.

Our group and others have previously shown that Toll-like receptor 4 (TLR-4) inactivation prevents burn-induced myocardial contractile dysfunction; however, the molecular mechanisms that are involved in this cardioprotection are not well defined. This present study examines the involvement of TLR-4 in the cardiac inflammatory response to thermal insult. C3H/HeJ (TLR-4 mutant mice) and C3H/HeN wild-type (WT) mice were subjected to either a sham burn or 40% full-thickness burn injury and were fluid resuscitated with lactated Ringer using the Parkland formula. Mice (n = 7-9 per group) were killed at 2, 4, or 24 h postsham or burn, and heart tissue was harvested. Immunoblotting was performed to evaluate phosphorylated p38 mitogen-activated protein kinase (MAPK), nuclear p50, and cytoplasmic p50. Nuclear factor-kappaB was also characterized via electrophoretic mobility shift assay. Systemic and cardiac myocyte secretion of TNF-alpha, IL-1 beta, IL-6, and IL-10 were measured by enzyme-linked immunosorbent assay. Burn injury in WT mice promoted myocardial inflammatory signaling that included increased expression of phosphorylated p38 MAPK, nuclear p50, and increased cardiac myocyte secretion of cytokines. Systemic cytokines were also increased in WT animals, although not to the extent of the myocardial cytokine expression. Toll-like receptor 4 inactivation resulted in an attenuation of several burn-induced responses, including phosphorylation of p38 MAPK, nuclear translocation of nuclear factor-kappaB, and cytokine secretion. These data suggest that burn injury initiates an inflammatory response via Toll/IL-1 signaling in the heart, which contributes to cardiac injury and contractile dysfunction.