Potential biomarkers of an exaggerated response to endotoxemia

Serial plasma protein analysis was used to study the acute plasma proteome response to endotoxemia (presence of toxic bacterial products called endotoxins in the blood stream). Plasma samples from healthy volunteers before and multiple time points up to 24 h following administration of low-dose endotoxin were evaluated. Plasma protein profiles were obtained by rapid extraction of whole plasma followed by analysis with matrix-assisted laser desorption ionisation-time of flight mass spectrometry. The profiles were unique to each individual and stable over the time of the experiment. Administration of low-dose endotoxin caused profound change in six of 18 individuals. At 8 h many proteins showed quantitative oxidation, in addition to the appearance of new components and disappearance of common baseline components. An exceptionally intense new component at 4154 mass units was identified as the activation peptide of C1 esterase inhibitor. While recovery of baseline protein structure was nearly complete by 24 h, serum amyloid A, an acute-phase reactant, was still increasing and minor profile changes persisted. Clinical features did not distinguish these extreme responders from others, suggesting that plasma proteome changes offered unique insights into and potential biomarkers of subclinical events following endotoxin exposure.     

Associations among prostaglandin F2alpha, plasma zinc, copper and iron concentrations and fetal loss in cows and mares

The objective of this study was to test the hypothesis that PGF2alpha is associated with abortion and changes in plasma Zn, Cu, and Fe concentrations in cows and mares in their first trimester of pregnancy. Eleven pregnant cows were infused with endotoxin (n = 5) or endotoxin plus an inhibitor of cycloxygenase, flunixin meglumine (n = 6). Blood was collected over a 5-d period. Additionally, 4 mares were treated every 24 h with cloprostenol sodium and blood was collected hourly until abortion. Plasma Zn, Cu, and Fe were determined. Three of five cows treated with endotoxin aborted, but none of the six cows treated with endotoxin and flunixin meglumine aborted. Aborting cows had lower plasma Zn (P = 0.048) over the 5-d study period compared with the nonaborting cows. The changes in Zn corresponded to release of PGF2alpha. All 4 mares aborted and plasma Zn concentrations were lower (P = 0.008) and Cu/Zn was higher (P = 0.02) 12 h after cloprostenol treatment. Plasma Zn may be a useful biomarker for risk of spontaneous abortion, and the decline in plasma Zn may be caused by PGF2alpha.     

Comparing SILAC and two-dimensional gel electrophoresis image analysis for profiling urokinase plasminogen activator signaling in ovarian cancer cells

Two-dimensional gel electrophoresis (2-DE) image analysis is conventionally used for comparative proteomics. However, there are a number of technical difficulties associated with 2-DE protein separation that limit the depth of proteome coverage, and the image analysis steps are typically labor-intensive and low-throughput. Recently, mass spectrometry-based quantitation strategies have been described as alternative differential proteome analysis techniques. In this study, we investigated changes in protein expression using an ovarian cancer cell line, OVMZ6, 24 h post-stimulation with the relatively weak agonist, urokinase-type plasminogen activator (uPA). Quantitative protein profiles were obtained by MALDI-TOF/TOF from stable isotope-labeled cells in culture (SILAC), and these results were compared to the quantitative ratios obtained using 2-DE gel image analysis. MALDI-TOF/TOF mass spectrometry showed that differential quantitation using SILAC was highly reproducible (approximately 8% coefficient of variation (CV)), and this variance was considerably lower than that achieved using automated 2-DE image analysis strategies (CV approximately 25%). Both techniques revealed subtle alterations in cellular protein expression following uPA stimulation. However, due to the lower variances associated with the SILAC technique, smaller changes in expression of uPA-inducible proteins could be found with greater certainty.     

创伤后血二胺氧化酶的变化与肠粘膜损伤

探讨创伤感染对肠道屏障功能的影响。以山羊、大鼠手术+失血再灌注+内毒素(LPS),大鼠肠缺血再灌注和犬低温枪伤多种创伤动物为模型,测定血浆二胺氧化酶(DAO)活性,并测定血乳酶、TNF和LPS含量。观察小肠病理形态改变。结果:失血再灌注后血浆DAO水平显著升高,给予内毒素后山羊血DAO水平再度升高。血浆DAO的变化与血乳酸,TNF和LPS变化呈高度相关(r=0.872,0.842和0.817,p<0.01)。光、电镜检查表明肠粘膜损伤,失血再灌注损伤可致肠粘膜屏障功能损伤,测定血浆DAO活性变化对判断小肠粘膜损伤有帮助     

内毒素和细胞因子在腹部火器伤肠管穿透后血液中的变化及意义

目的：探讨内毒素和细胞因子在腹部火器伤肠管穿透后血液中的变化规律及意义。方法：健康长白仔猪42头随机等分为对照组和伤后1h、2h、4h、8h、12h和24h组,实验组建立腹部火器伤肠管穿透模型后,用显色基质鲎试剂法检测各组血浆内毒素水平,采用双抗体夹心ELISA法测定各组动物血清TNF-α、IL-6水平,并观察各个时间点的体温变化。结果：实验各组的血浆内毒素水平及血清TNF-α、IL-6水平均明显高于对照组（P〈0.05）,血浆内毒素于伤后8h达到高峰,伤后12h仍维持在高峰值水平（P〈0.05）;血清TNF-α在伤后12h为（94.36±10.18）ng/L,IL-6在伤后12h为（1218.35±74.00）ng/L,二者均于伤后12h达到高峰并与伤后血浆内毒素水平变化一致。伤后动物体温逐渐升高,在伤后12h、24h实验组的平均体温达40℃以上。结论：腹部火器伤肠穿孔后内毒素血症可能诱导了血液中TNF-α、IL-6的产生,并参与了腹部肠管火器伤后机体的病理生理过程。     

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

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

Ethanol modulates gut ischemia/reperfusion-induced liver injury in rats

Whereas both ethanol and gut ischemia/reperfusion (I/R) are known to alter hepatic microvascular function, little is known about the influence of ethanol consumption on the hepatic microvascular responses to I/R. The objective of this study was to determine whether acute ethanol administration exacerbates the hepatic microvascular dysfunction induced by gut I/R. Rats were exposed to gut ischemia for 30 min followed by reperfusion. Intravital videomicroscopy was used to monitor leukocyte recruitment and the number of nonperfused sinusoids (NPS). Plasma alanine aminotransferase (ALT), tumor necrosis factor-alpha (TNF-alpha), and endotoxin concentrations were monitored. In separate experiments, ethanol was administered 15 min or 24 h before gut ischemia. In control rats, gut I/R increased the number of stationary leukocytes and NPS. It also elevated the plasma ALT, TNF-alpha, and endotoxin with a corresponding increase in intestinal mucosal permeability. Low-dose ethanol consumption 15 min before gut ischemia blunted the gut I/R-induced leukostasis and elevations in plasma TNF-alpha and ALT. However, high-dose ethanol consumption aggravated the gut I/R-induced increases in leukostasis and increases in plasma endotoxin and ALT. When ethanol was administered 24 h before, high-dose ethanol aggravated the gut I/R-induced hepatocellular injury, but low-dose ethanol did not have any effects on it. These results suggest that low-dose ethanol consumption shortly before gut ischemia attenuates the hepatic inflammatory responses, microvascular dysfunction, and hepatocellular injury elicited by gut I/R, whereas high-dose ethanol consumption appears to significantly aggravate these gut I/R-induced responses.     

Direct tandem mass spectrometry reveals limitations in protein profiling experiments for plasma biomarker discovery

The low molecular weight plasma proteome and its biological relevance are not well defined; therefore, experiments were conducted to directly sequence and identify peptides observed in plasma and serum protein profiles. Protein fractionation, matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) profiling, and liquid-chromatography coupled to MALDI tandem mass spectrometry (MS/MS) sequencing were used to analyze the low molecular weight proteome of heparinized plasma. Four fractionation techniques using functionally derivatized 96-well plates were used to extract peptides from plasma. Tandem TOF was successful for identifying peptides up to m/z 5500 with no prior knowledge of the sequence and was also used to verify the sequence assignments for larger ion signals. The peptides (n>250) sequenced in these profiles came from a surprisingly small number of proteins (n approximately 20), which were all common to plasma, including fibrinogen, complement components, antiproteases, and carrier proteins. The cleavage patterns were consistent with those of known plasma proteases, including initial cleavages by thrombin, plasmin and complement proteins, followed by aminopeptidase and carboxypeptidase activity. On the basis of these data, we discuss limitations in biomarker discovery in the low molecular weight plasma or serum proteome using crude fractionation coupled to MALDI-MS profiling.     

Alpha tocopherol supplementation elevates plasma apolipoprotein A1 isoforms in normal healthy subjects

Plasma alpha-tocopherol (AT) concentrations are inversely related to cardiovascular (CV) risk; however, intervention studies with AT have failed to show any consistent benefit against CV disease (CVD). Proteomics offers the opportunity to examine novel effects of AT supplementation on protein expression and therefore improve our understanding of the physiological roles of AT. Thus, to investigate the effects of AT supplementation on the plasma proteome of healthy subjects we have undertaken a double-blind, randomised, parallel design supplementation study in which healthy subjects (n = 32; 11 male and 21 female) consumed AT supplements (134 or 268 mg/day) or placebo capsules for up to 28 days. Plasma samples were obtained before supplementation and after 14 and 28 days of supplementation for analysis of changes in the plasma proteome using 2-DE and MALDI-MS. Using semiquantitative proteomics, we observed that proapolipoprotein A1 (identified by MS and Western blotting) was altered at least two-fold. Using quantitative ELISA techniques, we confirmed a significant increase in plasma apolipoprotein A1 concentration following supplementation with AT which was both time and dose dependent (p < 0.01 after 28 days supplementation with 268 mg AT/day). These data demonstrate the time and dose sensitivity of the plasma proteome to AT supplementation.     

血浆蛋白质组学的研究进展

血浆蛋白质组学是研究血浆蛋白质的功能和变化的一门科学。血浆中蕴藏着生命机体的所有信息,因此只有彻底了解血浆中存在哪些蛋白质,才能知道如何利用血浆来预测人体对疾病的易感性并监控疾病的进程,以期达到对疾病进行早诊断早治疗。由于血浆蛋白质组动态范围大,给研究带来了很大的困难。尤其是高丰度蛋白质的存在影响了低丰度蛋白质的检测率。而低丰度蛋白质都是有意义的具有临床诊断价值的蛋白质。因此去除高丰度蛋白质的干扰成了血浆蛋白质组学研究的关键。近年来,血浆蛋白质组学相关研究技术也得到了长足进展,为深入研究血浆蛋白质做出了重要贡献。血浆蛋白质组学作为一种无创性的研究方法,值得我们去探讨。本文就血浆蛋白质组学研究进展情况做一简要综述。     

Calorimetry outside the box: a new window into the plasma proteome

Differential scanning calorimetry provides a new window into the plasma proteome. Plasma from normal individuals yields a characteristic, reproducible thermogram that appears to represent the weighted sum of denaturation profiles of the most abundant constituent plasma proteins. Plasma from diseased individuals yields dramatically different signature thermograms. Thermograms from individuals suffering from rheumatoid arthritis, systemic lupus, and Lyme disease were measured. Each disease appears to have a distinctive and characteristic thermogram. The difference in thermograms between normal and diseased individuals is not caused by radical changes in the concentrations of the most abundant plasma proteins but rather appears to result from interaction of as yet unknown biomarkers with the major plasma proteins. These results signal a novel use for calorimetry as a diagnostic tool.     

Simultaneous elevation of plasma insulin and catecholamines during endotoxicosis in the conscious and anesthetized rat

Plasma levels of glucose, insulin and catecholamines were assessed during the early phase of sub-lethal endotoxicosis in fasted male rats which were either conscious or continuously anesthetized with sodium pentobarbital. Exogenous glucose challenge was administered during endotoxicosis to probe insulin release at a time when plasma catecholamines were elevated. An endogenous hyperglycemia occurred following endotoxin but was moderated by continuous pentobarbital anesthesia. Plasma insulin was elevated in the conscious but not anesthetized rats during endogenous hyperglycemia following endotoxin. Hyperglycemia with exogenous glucose elevated plasma insulin levels in both conscious and anesthetized groups and occurred in the presence of elevated levels of norepinephrine, epinephrine and dopamine. Simultaneous elevation of plasma catecholamine and insulin levels during endotoxicosis suggests that glucose utilization may be promoted at the same time that glucose is mobilized through adrenergic mechanisms. These events may contribute to the rapid depletion of carbohydrate stores leading to the hypoglycemia of the agonal stage of endotoxic shock.     

A proteomic study of the HUPO Plasma Proteome Project's pilot samples using an accurate mass and time tag strategy

Characterization of the human blood plasma proteome is critical to the discovery of routinely useful clinical biomarkers. We used an accurate mass and time (AMT) tag strategy with high-resolution mass accuracy cLC-FT-ICR MS to perform a global proteomic analysis of pilot study samples as part of the HUPO Plasma Proteome Project. HUPO reference serum and citrated plasma samples from African Americans, Asian Americans, and Caucasian Americans were analyzed, in addition to a Pacific Northwest National Laboratory reference serum and plasma. The AMT tag strategy allowed us to leverage two previously published "shotgun" proteomics experiments to perform global analyses on these samples in triplicate in less than 4 days total analysis time. A total of 722 (22% with multiple peptide identifications) International Protein Index redundant proteins, or 377 protein families by ProteinProphet, were identified over the six individual HUPO serum and plasma samples. The samples yielded a similar number of identified redundant proteins in the plasma samples (average 446 +/- 23) as found in the serum samples (average 440 +/- 20). These proteins were identified by an average of 956 +/- 35 unique peptides in plasma and 930 +/- 11 unique peptides in serum. In addition to this high-throughput analysis, the AMT tag approach was used with a Z-score normalization to compare relative protein abundances. This analysis highlighted both known differences in serum and citrated plasma such as fibrinogens, and reproducible differences in peptide abundances from proteins such as soluble activin receptor-like kinase 7b and glycoprotein m6b. The AMT tag strategy not only improved our sample throughput but also provided a basis for estimated quantitation.     

Selected expression profiling of full-length proteins and their variants in human plasma

With increased interest in clinical proteomics—the comparative investigation of differential protein expression patterns for use in the diagnostic and prognostic assessment of disease states—the demand for techniques that can readily identify changes in select proteome components is greater than ever before. This article describes a targeted proteomics approach to recover and quantify C-reactive protein (CRP) directly from human plasma. CRP, a putative biomarker for cardiac health, was isolated from microliter volumes of human plasma by using novel proteomics tools that combine micro-scale affinity capture with matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) detection. Native CRP was analyzed along with serum amyloid P component (SAP) and retinol binding protein (RBP), that were intentionally targeted to generate a selected protein expression profile. A number of qualitative changes were readily observed within these profiles, including micro heterogeneity in the SAP glycan, C-terminally truncated versions of RBP, and detection of a novel truncated variant of CRP. After quantitative validation of increasing plasma CRP concentrations, the approach was applied to the analysis of eight plasma samples obtained from individuals with known medical histories. The result of the analyses are eight protein profiles, revealing increasing CRP levels that can be associated with individuals ailing from post-surgery inflammation, chronic rheumatoid arthritis, and recent acute myocardial infarction. The technique described in this article lays the foundation for selected protein profiling for use in biomarker discovery, as well as in clinical and diagnostic applications.     

Assessment of protein stability in cerebrospinal fluid using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry protein profiling

Recent studies have evaluated proper acquisition and storage procedures for the use of serum or plasma for mass spectrometry (MS)-based proteomics. The present study examines the proteome stability of human cerebrospinal fluid (CSF) over time at 23°C (room temperature) and 4°C using surface-enhanced laser desorption/ionization time-of-flight MS. Data analysis revealed that statistically significant differences in protein profiles are apparent within 4 h at 23°C and between 6 and 8 h at 4°C. Inclusion of protease and phosphatase inhibitor cocktails into the CSF samples failed to significantly reduce proteome alterations over time. We conclude that MS-based proteomic analysis of CSF requires careful assessment of sample collection procedures for rapid and optimal sample acquisition and storage.     

An update on medium- and low-abundant blood plasma proteome of horse

The main objectives of the study were to: (1) deeply analyse the serum protein composition of Equus caballus, (2) assess the effectiveness of the high-abundant protein depletion and improve the concentration of medium- and low-abundant proteins. The analysis were performed on the blood plasma of three healthy part-Arabian mares. The implementation of two-dimensional electrophoresis and matrix-assisted laser desorption/ionisation – time of flight mass spectrometry allowed us to establish a horse plasma proteome map. Serum proteins were resolved at pH 4 to 7, followed by 12% SDS-PAGE. As a result 136 spots were successfully identified, representing the products of 46 unique genes. Of these, 22 gene products have not been previously identified in horse serum/plasma samples using proteomic tools. Gene ontology analysis showed that almost 30% of all identified gene products belong to the coagulation and complement cascades. These results can undoubtedly serve as a useful and prospective prerequisite for the future analysis of horse plasma proteome changes in different physiological and pathophysiological conditions. The use of the medium- and low-abundant protein enrichment tool increased their abundance and allowed us to identify a higher number of protein gene products. The highest depletion efficiency was observed for the most abundant plasma proteins, that is albumin, IgG heavy chains and serotransferrin.     

Alterations in the proteome of the Euprymna scolopes light organ in response to symbiotic Vibrio fischeri

During the onset of the cooperative association between the Hawaiian sepiolid squid Euprymna scolopes and the marine luminous bacterium Vibrio fischeri, the anatomy and morphology of the host's symbiotic organ undergo dramatic changes that require interaction with the bacteria. This morphogenetic process involves an array of tissues, including those in direct contact with, as well as those remote from, the symbiotic bacteria. The bacteria induce the developmental program soon after colonization of the organ, although complete morphogenesis requires 96 h. In this study, to determine critical time points, we examined the biochemistry underlying bacterium-induced host development using two-dimensional polyacrylamide gel electrophoresis. Specifically, V. fischeri-induced changes in the soluble proteome of the symbiotic organ during the first 96 h of symbiosis were identified by comparing the protein profiles of symbiont-colonized and uncolonized organs. Both symbiosis-related changes and age-related changes were analyzed to determine what proportion of the differences in the proteomes was the result of specific responses to interaction with bacteria. Although no differences were detected over the first 24 h, numerous symbiosis-related changes became apparent at 48 and 96 h and were more abundant than age-related changes. In addition, many age-related protein changes occurred 48 h sooner in symbiotic animals, suggesting that the interaction of squid tissue with V. fischeri cells accelerates certain developmental processes of the symbiotic organ. These data suggest that V. fischeri-induced modifications in host tissues that occur in the first 24 h of the symbiosis are independent of marked alterations in the patterns of abundant proteins but that the full 4-day morphogenetic program requires significant alteration of the host soluble proteome.