Marilena Formato

A proteomic approach to differentiate histologically classified stable and unstable plaques from human carotid arteries

OBJECTIVES By using proteomics we isolated and identified proteins that were expressed/retained in stable and unstable human carotid artery atherosclerotic plaques. METHODS The criteria for plaque instability were the presence of a thin fibrous cap or fissured cap covering the foamy or necrotic core, and the presence of overt, hemorrhagic, ulcerated or thrombotic plaques. Proteins were extracted from finely minced endarterectomy specimens (19 stable and 29 unstable plaques) and separated by two-dimensional gel electrophoresis. Coomassie Blue-stained gels were analysed using PD-Quest software. RESULTS A total of 57 distinct spots corresponding to 33 different proteins were identified by matrix assisted laser desorption/ionization mass spectrometry using the NCBI database. Most of the spots were present in both types of extracts, although significantly (p<0.05) differing in abundance between them. Compared to stable plaque, unstable ones showed reduced abundance of: protective enzymes SOD3 and GST, small heat shock proteins HSP27 and HSP20, annexin A10, and Rho GDI. In unstable plaques the more abundant proteins were: ferritin light subunit, SOD 2 and fibrinogen fragment D. For fibrinogen fragment D, the increased levels in unstable versus stable plaques was confirmed by Western blot analysis. CONCLUSIONS Since many of the differentially expressed proteins are known to have a functional role in inflammation and oxidative stress, we speculate that they may be involved in events relating to plaque stability.

The gamma globin chain heterogeneity of the Sardinian newborn baby.

The hemoglobin of 2048 newborn babies from Sardinia was analyzed by isoelectric focusing and polyacrylamide gel electrophoresis in order to determine the level of Hb F-Sardinia (with A gamma T) and the G gamma chain. Hb F-Sardinia values of 15.5 +/- 2.6% were present in the A gamma T heterozygote whereas 30.7 +/- 5.2% were present in the homozygote. The A gamma T gene frequency was 0.17. Most of the babies tested showed the normal G gamma level either in the absence of the A gamma T anomaly (69.6 +/- 4.1%), or in the presence of the anomaly in both the heterozygous state (70.9 +/- 4.8%) and the homozygous state (71.1 +/- 3.4%). Similar values were shown in nine homozygotes for beta-thalassemia discovered during the screening. Nine newborn babies (0.44%) showed particularly low G gamma levels (38.3 +/- 6.8%) whereas 18 newborn babies showed high G gamma levels (83.9 +/- 2.6%). The frequencies of the anomalies (0.0022 for the low G gamma and 0.0044 for the high G gamma) were the lowest observed in Caucasian and other ethnic groups. Data suggest the presence of abnormal gamma globin gene arrangements in the Sardinian population.

Evidence for a Proinflammatory and Proteolytic Environment in Plaques From Endarterectomy Segments of Human Carotid Arteries

ObjectivesBased on previous observations on apolipoprotein(a), apo(a), in human unstable carotid plaques, we explored whether in the inflammatory environment of human atheroma, proteolytic events affect other hepatic and topically generated proteins in relation to the issue of plaque stability. Methods and ResultsForty unstable and 24 stable plaques from endarterectomy segments of affected human carotid arteries were extracted with buffered saline (PBS) and then 6 mol/L guanidine-hydrochloride (GdHCl) to identify loosely and tightly bound products, respectively. The extracts were studied before and after ultracentrifugation at d 1.21 g/mL. In the extracts, the concentrations of interleukin (IL)-6, −8, and −18 were significantly higher in the unstable plaques and correlated to those of MMP-2 and MMP-9. By Western blots, both apoB and apo(a) were highly fragmented and mostly present in the d 1.21 bottom that also contained fragments of apoE (10 and 22 kDa), decorin, biglycan, and versican. Fragmentation was higher in the unstable plaques. In baseline plasmas, concentrations of lipids, lipoproteins, and ILs did not differ between patients with unstable and stable plaques. ConclusionsIn unstable and to a lesser extent in stable plaques, there is a proinflammatory and proteolytic microenvironment with the generation of fragments with potential pathobiological significance that requires investigation.

Structural and functional modifications of human aorta proteoglycans in atherosclerosis.

Proteoglycans (PGs) were extracted from minced normal human aorta intima and media and adjacent atherosclerotic plaques. Samples obtained from each individual artery which showed different degrees of atherosclerotic involvement were studied separately. Comparing normal and atherosclerotic areas from the same aorta, the hexuronic acid content was always lower in the atherosclerotic minces. Atherosclerotic samples always contained a higher percentage amount of chondroitinase AC resistant material. PGs were sequentially extracted with increasing guanidine hydrochloride (GuHCl) concentrations. 0.4 M GuHCl extracted about 13% of total PGs, containing mostly chondroitin sulphate (CS), whilst 4 M GuHCl extracted about 50% of total PGs, containing CS, dermatan sulphate (DS), heparan sulphate and hyaluronic acid. PGs from atherosclerotic minces showed a higher DS amount, based on electrophoretic glycosaminoglycan (GAG) analysis. PGs extracted with 4 M GuHCl were further characterized by gel-chromatography and by CsCl density gradient centrifugation. The relative content of PGs with highest hydrodynamic size appeared to be markedly reduced in all the atherosclerotic samples. LDL/GAGs and LDL/PGs interactions were studied by affinity chromatography. GAGs obtained by papain digestion of PGs extracted from atherosclerotic areas contained a glycosaminoglycuronan interacting more strongly with human LDL than GAGs from normal areas of the same artery. The complete elution of PGs required higher NaCl concentration than GAGs. Moreover, PGs from atherosclerotic samples showed higher affinity for LDL than PGs from normal areas of the same aorta.

Fine structure of glycosaminoglycans from fresh and decellularized porcine cardiac valves and pericardium.

Cardiac valves are dynamic structures, exhibiting a highly specialized architecture consisting of cells and extracellular matrix with a relevant proteoglycan and glycosaminoglycan content, collagen and elastic fibers. Biological valve substitutes are obtained from xenogenic cardiac and pericardial tissues. To overcome the limits of such non viable substitutes, tissue engineering approaches emerged to create cell repopulated decellularized scaffolds. This study was performed to determine the glycosaminoglycans content, distribution, and disaccharides composition in porcine aortic and pulmonary valves and in pericardium before and after a detergent-based decellularization procedure. The fine structural characteristics of galactosaminoglycans chondroitin sulfate and dermatan sulfate were examined by FACE. Furthermore, the mechanical properties of decellularized pericardium and its propensity to be repopulated by in vitro seeded fibroblasts were investigated. Results show that galactosaminoglycans and hyaluronan are differently distributed between pericardium and valves and within heart valves themselves before and after decellularization. The distribution of glycosaminoglycans is also dependent from the vascular district and topographic localization. The decellularization protocol adopted resulted in a relevant but not selective depletion of galactosaminoglycans. As a whole, data suggest that both decellularized porcine heart valves and bovine pericardium represent promising materials bearing the potential for future development of tissue engineered heart valve scaffolds.

Plasma levels of C-reactive protein, leptin and glycosaminoglycans during spontaneous menstrual cycle: differences between ovulatory and anovulatory cycles.

PurposeTo assess the plasma levels of the inflammatory markers such as C-reactive protein (CRP), leptin, and glycosaminoglycans (GAGs) during the menstrual cycle.MethodsEighteen healthy volunteers were divided into two groups according to the presence of ovulatory or anovulatory menstrual cycles. Blood samples were collected at different time points: at the menstrual phase (days 2–3), periovulatory phase (days 12–13), and luteal phase (days 23–24). CRP and leptin concentrations were measured by enzyme immunoassay. GAGs were isolated using ion-exchange chromatography on DEAE-Sephacel and quantified as hexuronate. The structural characterization of chondroitin sulfate (CS) isomers was performed by fluorophore-assisted carbohydrate electrophoresis (FACE).ResultsIn the women with ovulatory cycles, plasma GAG levels differed significantly during menstrual cycle, with increased values at the periovulatory with respect to the menstrual phase. No significant differences in CRP and leptin concentrations were observed through the menstrual cycle in both the examined cycles, but inter-group analysis revealed significant differences of CRP and leptin levels between the ovulatory and anovulatory cycles with higher values at periovulatory phase in the ovulatory cycles.ConclusionsThere are no fluctuations of both total GAG concentration and CS isomer content during menstrual cycle in the anovulatory cycles. A significant correlation between CRP and gonadotrophins was found. There is no significant difference in CRP across the menstrual cycle among ovulatory cycles, but there is a trend toward higher CRP at the periovulatory than the other phases, consistent with the significant difference in CRP between ovulatory and anovulatory cycles at the periovulatory phase. Both the trend and the significant result suggest an elevation in CRP with ovulation. These observations provide additional evidences to the hypothesis that the ovulation is an inflammatory-like phenomenon.

Proteomic Analysis of Plasma-Purified VLDL, LDL, and HDL Fractions from Atherosclerotic Patients Undergoing Carotid Endarterectomy: Identification of Serum Amyloid A as a Potential Marker

Apolipoproteins are very heterogeneous protein family, implicated in plasma lipoprotein structural stabilization, lipid metabolism, inflammation, or immunity. Obtaining detailed information on apolipoprotein composition and structure may contribute to elucidating lipoprotein roles in atherogenesis and to developing new therapeutic strategies for the treatment of lipoprotein-associated disorders. This study aimed at developing a comprehensive method for characterizing the apolipoprotein component of plasma VLDL, LDL, and HDL fractions from patients undergoing carotid endarterectomy, by means of two-dimensional electrophoresis (2-DE) coupled with Mass Spectrometry analysis, useful for identifying potential markers of plaque presence and vulnerability. The adopted method allowed obtaining reproducible 2-DE maps of exchangeable apolipoproteins from VLDL, LDL, and HDL. Twenty-three protein isoforms were identified by peptide mass fingerprinting analysis. Differential proteomic analysis allowed for identifying increased levels of acute-phase serum amyloid A protein (AP SAA) in all lipoprotein fractions, especially in LDL from atherosclerotic patients. Results have been confirmed by western blotting analysis on each lipoprotein fraction using apo AI levels for data normalization. The higher levels of AP SAA found in patients suggest a role of LDL as AP SAA carrier into the subendothelial space of artery wall, where AP SAA accumulates and may exert noxious effects.

Differential distribution of structural components and hydration in aortic and pulmonary heart valve conduits: impact of detergent-based cell removal

Evaluation of the physiological performance of biological scaffolds for tissue engineering applications has been mostly based on biophysical and morphological methods, with limited attention paid to the quantitative contribution of the main structural components to native and/or treated valve assemblies. In the present study quantitation addressed the porcine leaflet, sinus and adjacent wall of aortic and pulmonary valved conduits before and after detergent-based cell removal. Collagen, elastin, glycosaminoglycan, lipid and water contents were expressed in terms of relative concentration and volume fraction in order to assess their effective contribution to the native tissue and to changes following decellularization procedures. The main findings were recognition of unexpectedly large water and underestimated collagen contents, differential distribution of elastin between the sectors and of glycosaminoglycan along the conduits and pulmonary scaffold destabilization upon cell removal, not found in the aortic case. Simultaneous investigations allowed consistent comparisons between native and decellularized tissues and added analytical knowledge crucial for designing realistic constitutive models. We have provided a quantitative structural foundation for earlier biomechanical findings in pulmonary leaflets and the basis for validation of theoretical assumptions still lacking the support of experimental evidence in both conduits. Future insights into the distribution of load-bearing components in human conduits are likely to provide indications important to optimize the surgical positioning of valvular grafts.

DNA polymorphisms in North Sardinian newborns and their linkage with abnormal γ globin gene arrangements and with βo-thalassemia

Fetal hemoglobin analysis and globin gene mapping have identified one type of βo-thalassemia and four different γ globin gene arrangements among newborn babies from the northern part of Sardinia. The βo-thalassemia with a nonsense mutation at codon 39 was found on two chromosomes, each with a distinct pattern of polymorphic restriction sites; one had the AγT (Aγ75 Ile → Thr) mutation, while the second did not. Four closely related haplotypes were identified for chromosomes with the AγT mutation. The γ-thalassemia heterozygosity with the —GAγ— hybrid gene fell into two categories. One apparently originated through crossing-over between mismatched chromosomes characterized by the most common haplotype, while the other had polymorphisms resembling those of a less frequently occurring chromosome. Chromosomes with the —Gγ—AGγ—Aγ— triplication had polymorphic sites to be expected for this condition, being complimentary to the —GAγ— thalassemias. Of the two additional γ globin gene variations the —Gγ—Gγ— arrangement was associated with the chromosome with the most commonly occurring haplotype, while the chromosome with the —Aγ—Aγ— arrangement had a haplotype characteristic for that with the AγT mutation, which identified an —Aγ—AγT— arrangement. The incidental discovery of a silent β-chain mutant, Hb Hamilton, with the Val → Ile substitution at position β11, in five newborns was also reported.

Albumin-bound low molecular weight thiols analysis in plasma and carotid plaques by CE

We describe a new method for the quantification of low molecular weight thiols, as homocysteine, cysteine, cysteinylglycine, glutamylcysteine and glutathione bound to human plasma albumin. After albumin isolation and purification by SDS-PAGE, thiols were freed from protein with tri-n-butylphosphine and successively derivatized with 5-iodoacetamidofluorescein. Samples were then injected and quantified in about 18 min by CE with laser induced fluorescence detection. Precision tests indicate a good repeatability of the method both for migration times (RSD<0.63%) and areas (RSD<2.98%). The method allows to measure all five low molecular weight thiols released from just 3 microg of albumin thus improving the other described methods in which only three or four thiols were detected. Due to the elevated sensitivity (LOD of 0.3 pM for all thiols), also low molecular weight thiols bound to albumin filtered in tissues could be quantified.