Identification of Major Allergens in Watermelon

<i>Background:</i> Watermelon is a worldwide consumed<i> Cucurbitaceae </i>fruit that can elicit allergic reactions. However, the major allergens of watermelon are not known. The aim of this study is to identify and characterize major allergens in watermelon. <i>Methods:</i> Twenty-three patients allergic to watermelon took part in the study. The diagnosis was based on a history of symptoms and positive skin prick-prick tests to watermelon, confirmed by positive open oral challenge testing to watermelon pulp. Allergenic components were detected by SDS-PAGE and immunoblotting. Molecular characterization of IgE-binding bands was performed by N-terminal amino acid sequencing and mass spectrometry. Allergens were purified combining several chromatographic steps. <i>Results:</i> Several IgE binding bands (8–120 kDa) were detected in watermelon extract. Three major allergens were identified as malate dehydrogenase (36 kDa), triose phosphate isomerase (28 kDa) and profilin (13 kDa). Purified allergens individually inhibited IgE binding to the whole watermelon extract. <i>Conclusions:</i> All in all these results indicate that malate dehydrogenase, triose phosphate isomerase and profilin are major allergens involved in watermelon allergy.

Proteomic Biomarkers of Atherosclerosis

SUMMARY: Biomarkers provide a powerful approach to understanding the spectrum of cardiovascular diseases. They have application in screening, diagnostic, prognostication, prediction of recurrences and monitoring of therapy. The "omics" tool are becoming very useful in the development of new biomarkers in cardiovascular diseases. Among them, proteomics is especially fitted to look for new proteins in health and disease and is playing a significant role in the development of new diagnostic tools in cardiovascular diagnosis and prognosis. This review provides an overview of progress in applying proteomics to atherosclerosis. First, we describe novel proteins identified analysing atherosclerotic plaques directly. Careful analysis of proteins within the atherosclerotic vascular tissue can provide a repertoire of proteins involved in vascular remodelling and atherogenesis. Second, we discuss recent data concerning proteins secreted by atherosclerotic plaques. The definition of the atheroma plaque secretome resides in that proteins secreted by arteries can be very good candidates of novel biomarkers. Finally we describe proteins that have been differentially expressed (versus controls) by individual cells which constitute atheroma plaques (endothelial cells, vascular smooth muscle cells, macrophages and foam cells) as well as by circulating cells (monocytes, platelets) or novel biomarkers present in plasma.

Proteomic analysis of early left ventricular hypertrophy secondary to hypertension: modulation by antihypertensive therapies

Untreated or poorly controlled arterial hypertension induced development of pathologic left ventricular hypertrophy (LVH), a common finding in hypertensive patients and a strong predictor of cardiovascular morbidity and mortality. The proteomic approach is a powerful technique to analyze a complex mixture of proteins in various settings. An experimental model of hypertension-induced early LVH was performed in spontaneously hypertensive rats, and the cardiac protein pattern compared with the normotensive Wistar Kyoto counterpart was analyzed. Fifteen altered protein spots were shown in the early stage of LVH. Compared with a previous animal model of established and regressed LVH, three protein spots were common in both models. These three altered protein spots corresponded to two unique proteins that were identified as Calsarcin-1 (CS-1) and ubiquinone biosynthesis protein COQ7 homolog. CS-1 is a negative regulator of the calcineurin/NF-AT pathway. Because upregulation in the expression levels of this protein was observed, the activation level of NF-kappaB by oxidative stress as an alternative pathway was investigated. It was found that antihypertensive therapies partially decreased oxidative stress and normalized the activation of NF-kappaB in the kidneys and aorta NF-kappaB activation but just moderately in the heart. This could be due to the interaction of any specific cardiac protein with any component of the NF-kappaB pathway. In this sense, CS-1 could be a good candidate because it is expressed preferentially in heart, to a lesser extent in smooth muscle cells, but not in kidney. Further investigations are necessary to elucidate the exact role of CS-1 and ubiquinone biosynthesis protein COQ7 in the setting of hypertension-induced LVH.

Allergy to human seminal fluid: cross-reactivity with dog dander

BACKGROUND

Human seminal plasma (HSP) allergy is uncommon, with symptoms ranging from vulvovaginal pruritus to life-threatening anaphylaxis. Although several seminal plasma allergens have been reported and their molecular masses have been estimated to range between 12 and 75 kd, the prostate-specific antigen (PSA) has recently been identified as a causative allergen. Given that in a large number of cases symptoms appeared during or after the first intercourse, a cross-reactivity phenomenon might be implicated.

OBJECTIVE

We sought to assess the presence of IgE cross-reactivity among proteins from dog epithelium and HSP and to attempt to identify the allergens involved.

METHODS

Forty-one patients with dog epithelium allergy were selected. One of them experienced anaphylaxis in contact with her husband's seminal plasma. Skin prick tests, serum specific IgE measurements, SDS-PAGE immunoblotting, and inhibition tests were performed to study the pattern of IgE-binding proteins and the potential cross-reactivity between HSP and dog epithelium. Mass spectrometry was carried out to identify the protein involved in allergy reactions.

RESULTS

Twenty-four percent of the sera from patients with dog epithelium allergy recognized an IgE-binding band of 28 kd in HSP immunoblotting. Mass spectrometry identified this band as the PSA. SDS-PAGE immunoblotting-inhibition showed a complete IgE-binding inhibition when sera from these patients were preincubated with dog dander extract.

CONCLUSIONS

IgE cross-reactivity among proteins from dog dander and human PSA is demonstrated.

Circulating human monocytes in the acute coronary syndrome express a characteristic proteomic profile

We examined the proteome of circulating monocytes of patients with acute coronary syndrome at different times in comparison to that of patients with stable coronary artery disease. On admission, the expression of 18 spot proteins was altered, 10 of which were totally absent. This pattern changed progressively, and at 6 months, there were no differences with the monocyte proteome of stable patients.

The proteome of endothelial cells

Endothelial cells form a continuous monolayer lining the inside face of all blood vessels, and present the ability to selectively control vascular permeability. The endothelium is involved in a wide variety of normal physiological and pathological processes. The endothelial dysfunction occurs under activation conditions, with the acquisition of many new functional, inflammatory, and immune properties, and as a consequence, endothelial cells display many different transcription profiles. We describe here the isolation and culture of the most useful model of human umbilical vein endothelial cells, and undertake the proteomic analysis under both basal quiescent condition and activated by stimulation with a proinflammatory cytokine. Series of two-dimensional electrophoresis have allowed us to detect a total of close to 600 polypeptide spots using 4.0-7.0 pH range in both culture conditions. We have selected 233 proteins by cross-matching the gels, and found that 70% showed an increase and 30% a decrease of expression levels in activated cells. Subsequent identification of 35 altered peptides is made by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry, as well as a study of posttranslational modifications. These global findings may contribute to understand the effects of pathological stimuli and the mechanisms that regulate vascular diseases.

Characterization of the human atheroma plaque secretome by proteomic analysis

Atherosclerosis is one of the most common causes of death in developed countries. Atherosclerosis is an inflammatory process that results in the development of complex lesions or plaques that protrude into the arterial lumen. Plaque rupture and thrombosis result in the acute clinical complications of myocardial infarction and stroke. Although certain risk factors (dyslipidemias, diabetes, hypertension) and humoral markers of plaque vulnerability (C-reactive protein, interleukin-6, -10 and -18, CD-40L) have been identified, a highly sensitive and specific biomarker or protein profile, which could provide information on the stability/vulnerability of atherosclerotic lesions, remains to be identified. Recently, we have described a novel strategy consisting in the proteomic analysis of proteins released by normal and atherosclerotic arterial walls in culture. This method enables harvesting of proteins that are only secreted by pathological or normal arterial walls. By focusing only on the secreted proteins found in the tissue culture media, there is an intended bias toward those molecules that would have a higher probability of later being found in plasma. Using this approach, we have shown that carotid atherosclerotic plaques cultured in vitro are able to secrete proteins, and also that a differential pattern of protein secretion of normal arteries vs pathological ones has been observed. In this chapter, the proteomic analysis of the human atheroma plaque secretome is described.

Characterization of HSP27 phosphorylation sites in human atherosclerotic plaque secretome

Atherosclerosis is one of the main causes of death in developed countries. Atheroma plaque formation is promoted by the interaction between the cells conforming the arterial wall, smooth muscle cells, and endothelial cells, together with lipoproteins and inflammatory cells (mainly macrophages and T-lymphocytes). These interactions can be mediated by proteins secreted from these cells, which therefore exert an important role in the atherosclerotic process. We recently described a novel strategy for the characterization of the human atherosclerotic plaque secretome, combining two-dimensional gel electrophoresis and mass spectrometry (MS). Among the identified proteins, two isoforms of heat shock protein 27 (HSP27), a protein recently described as a potential biomarker of atherosclerosis, were detected. However, the putative mechanisms in which HSP27 isoforms could be involved in the atherosclerotic process are unknown. Thus, the role that phosphorylated HSP27 could play in the atherosclerotic process is actually under study. The present work shows the strategies employed to characterize the phosphorylation in the HSP27 secreted by atheroma plaque samples. The application of liquid chromatography tandem mass spectrometry (MS/MS), as well as the combination of immobilized metal affinity chromatography methodology with matrix-assisted laser desorption/ionization MS/MS are described.

Depletion of high-abundance proteins in plasma by immunoaffinity subtraction for two-dimensional difference gel electrophoresis analysis

Blood plasma is believed the most complex human-derived proteome, containing other tissue proteome subsets. Almost all body cells communicate with the plasma, either directly or through tissues or biological fluids, and many of these cells release at least a part of their content into the plasma upon damage or death. A comprehensive, systematic characterization of the plasma proteome in the healthy and diseased states will greatly facilitate the development of biomarkers for early disease detection, clinical diagnosis, and therapy. However, the characterization of human plasma proteome is a very complicated task, owing to the wide dynamic range of concentration that separates the most abundant proteins and the less common ones (10-12 orders of magnitude). The removal of its predominant proteins by affinity chromatography using an FPLC system improves the presence of low-abundance proteins in two-dimensional gel electrophoresis (2DE). The "Multiple Affinity Removal System" (Agilent Technologies) retains albumin, IgG, IgA, haptoglobin, transferrin, and antitrypsin with high specificity and reproducibility. After depletion, we have independently analyzed the flow-through (low-abundance proteins), and the retained fractions, by 2DE (4.0-7.0 pH range). Image analysis of the stained gels revealed that more than 300 spots appeared in the retained fraction and about 1800 spots appeared in the nonretained fraction. This methodology is a valuable tool for clinical proteomics, because its reproducibility allows comparative studies and quantitative analysis by 2DE or two-dimensional differential gel electrophoresis of plasma or sera samples from subjects with different pathological or physiological conditions. In addition, the method allows the comparison of experimental results from different laboratories.

Characterization of circulating human monocytes by proteomic analysis

We describe a simple method for isolation of human blood monocytes with the high purity required for proteomic analysis, which avoids contamination by other blood cells (platelets and lymphocytes) and the most abundant plasma proteins (albumin and immunoglobulins). Blood monocytes were purified by gradient centrifugation followed by positive selection with monoclonal antibodies coupled to paramagnetic beads. This method is compatible with flow cytometry, which was used to assess the purity of the cell population. After solubilization of monocytes, the proteins where analyzed by two-dimensional gel electrophoresis in several pH ranges. Image analysis of gels allowed the reproducible detection and quantification of the spots present in the gel. This method is useful for clinical studies of monocytes from a large number of patients, owing to its rapidity and reproducibility, which permits comparative analysis of normal vs pathological samples and allows follow up of the expressed proteins of monocytes from each patient.

Atorvastatin modulates the profile of proteins released by human atherosclerotic plaques

The mechanisms by which hydroxymethylglutaryl CoenzymeA reductase inhibitors (statins) reduce atherosclerotic cardiovascular morbidity and mortality remain poorly understood. Statins have been shown to modulate the levels of different inflammatory proteins both in carotid atherosclerotic plaques and in the blood of patients with atherosclerosis. In this work, we hypothesize that statins could also modulate the levels of the proteins secreted by cultured atherosclerotic plaques. Thus, the secretomes obtained from complicated atherosclerotic plaques incubated in the presence/absence of atorvastatin (10 micromol/l, 24 h) were analysed and compared by two-dimensional electrophoresis, considering the fibrous adjacent areas as controls. In total, 54 proteins (83 protein isoforms) were identified by Mass Spectrometry (MS): 24 proteins were increased and 20 proteins decreased in atheroma plaque supernatants compared to controls. Some of these proteins, like Cathepsin D, could play a significant role in plaque instability, becoming a potential target for therapeutical treatment. Interestingly, 66% of the proteins differentially released by atherosclerotic plaques reverted to control values after administration of atorvastatin, among them, Cathepsin D. Moreover, plaques obtained from patients who received atorvastatin treatment prior to carotid endarterectomy showed decreased Cathepsin D expression relative to plaques from non-treated patients. In conclusion, this proteomic approach has shown that statins are able to modulate the secretome of atherosclerotic plaques, and new therapeutical targets for statins have been characterised.

Analysis of antihypertensive drugs in the heart of animal models: a proteomic approach

Arterial hypertension is the most frequent chronic disease and it is an important cause of morbidity and mortality in the developed world. Arterial hypertension is associated with such adverse effects as accelerated arteriosclerosis and pathological left ventricular hypertrophy, among others. The molecular mechanisms affecting left ventricular hypertrophy remain mostly unknown. The advent of proteome profiling has facilitated the elucidation of disease-associated proteins, paving the way for molecular diagnostics and the identification of novel therapeutic targets. We explored the proteomic profile of pathological left ventricular hypertrophy in comparison with normal heart in a model of rats and investigated the proteomic changes in response to different antihypertensive regimens in order to elucidate their cardioprotective effects. Here we describe in depth the protocol for this type of study.

Vascular Protection of Dual Therapy (Atorvastatin-Amlodipine) in Hypertensive Patients

Hypertension frequently coexists with other cardiovascular risk factors, such as hypercholesterolemia, and their combination is associated with a greater rate of cardiovascular events. Recent clinical data support that treatment of hypertensive patients with a combination of antihypertensive and lipid-lowering therapies leads to a higher reduction in the incidence of cardiovascular events. In the Anglo-Scandinavian Cardiac Outcomes Trial-Blood Pressure Lowering Arm (ASCOT-BPLA), an optimal prevention of cardiovascular events was reached in patients who were randomly assigned to atorvastatin and the amlodipine treatment. However, the potential underlying mechanisms of these vascular protective effects are not fully elucidated. Because experimental studies have shown that statins and calcium channel blockers have antiatherosclerotic effects, the effect of atorvastatin alone or in combination with amlodipine was analyzed in the protein secretion profile of atherosclerotic plaques that were cultured ex vivo. In this respect, the addition of atorvastatin and amlodipine to atherosclerotic plaques normalized the levels of the different released proteins to that obtained from healthy arteries. This review highlights recent clinical and experimental studies that support that a combined treatment of hypertensive patients with both statins and calcium channel blockers could promote a higher reduction in their global cardiovascular risk profile and associated mortality. As an example, the application of a proteomic approach to assess the modulation by atorvastatin alone or in combination with amlodipine on the proteins that are released by atherosclerotic plaques has allowed the identification of novel therapeutic targets by which these drugs could promote their additive/synergic effects.

Lipid cartography of atherosclerotic plaque by cluster-TOF-SIMS imaging

Several frozen vessels bearing atherosclerotic lesion were analysed by cluster TOF-SIMS (time-of-flight secondary ion mass spectrometry) to map their lipid (fatty acids, cholesterol, vitamin E, phosphatidic acids, phosphatidylinositols and triglycerides) content at a micrometric resolution.

Biology of atherosclerotic plaques: what we are learning from proteomic analysis

Atherosclerotic plaque rupture triggers the onset of cardiovascular complications such as myocardial infarction and stroke, which represent the main cause of death in western countries. Atherogenesis is a complex process characterized by lipid retention, proteolytic injury and a chronic inflammatory response. The resulting pathological vascular remodeling involves inflammatory cell recruitment, fibrosis, smooth muscle cell proliferation, neovascularization and intraplaque hemorrhage. However, the cellular and molecular mechanisms underlying cardiovascular dysfunction remain widely unknown. The development of differential proteomics allows the identification of novel proteins whose association with the genesis of atherosclerotic plaques is at present unforeseen in the light of available data. Moreover, different strategies have been used to discover new potential biomarkers which could be related to cardiovascular risk. The multi-factorial nature of cardiovascular diseases necessitates the use of biomarkers for early detection, for monitoring the response to therapy and to predict clinical outcome. In this review, we summarize the different proteomic approaches and recent findings that will help us to understand the mechanisms implicated in the pathogenesis of atherothrombosis.