Gian Maria D'Amici

Time-course investigation of SAGM-stored leukocyte-filtered red bood cell concentrates: from metabolism to proteomics

Background Results from recent, highly debated, retrospective studies raised concerns and prompted considerations about further testing the quality of long stored red blood cells from a biochemical standpoint. Design and Methods We performed an integrated mass spectrometry-based metabolomics and proteomics time-course investigation on SAGM-stored red blood cells. In parallel, structural changes during storage were monitored through scanning electron microscopy. Results We detected increased levels of glycolytic metabolites over the first 2 weeks of storage. From day 14 onwards, we observed a significant consumption of all metabolic species, and diversion towards the oxidative phase of the pentose phosphate pathway. These phenomena coincided with the accumulation of reactive oxygen species and markers of oxidation (protein carbonylation and malondialdehyde accumulation) up to day 28. Proteomics evidenced changes at the membrane protein level from day 14 onwards. Changes included fragmentation of membrane structural proteins (spectrin, band 3, band 4.1), membrane accumulation of hemoglobin, anti-oxidant enzymes (peroxiredoxin-2) and chaperones. While the integrity of red blood cells did not show major deviations at day 14, at day 21 scanning electron microscope images revealed that 50% of the erythrocytes had severely altered shape. We could correlate the scanning electron microscopy observations with the onset of vesiculation, through a proteomics snapshot of the difference in the membrane proteome at day 0 and day 35. We detected proteins involved in vesicle formation and docking to the membrane, such as SNAP alpha. Conclusions Biochemical and structural parameters did not show significant alterations in the first 2 weeks of storage, but then declined constantly from day 14 onwards. We highlighted several parallelisms between red blood cells stored for a long time and the red blood cells of patients with hereditary spherocytosis.

Peroxiredoxin-2 as a candidate biomarker to test oxidative stress levels of stored red blood cells under blood bank conditions

BACKGROUND: Several researches on aging red blood cells (RBCs)—performed both in vivo and under blood bank conditions—revealed that RBC membrane proteins undergo a number of irreversible alterations, mainly due to oxidative stress. The individuation of proteins to be used as indicators of irreversible RBC injury and to be proposed as candidate biomarkers of oxidative damage or aging status during blood storage is therefore of great interest.

Proteomic analysis of multiprotein complexes in the thylakoid membrane upon cadmium treatment.

The time course of the thylakoid membranes proteomic profile changes upon cadmium (Cd) addition to hydroponic Spinacia oleracea L. plants has been investigated. Two different proteomic approaches have been used: blue native gel electrophoresis followed by SDS-PAGE (2D BN-SDS-PAGE) and sucrose density gradient ultracentrifugation followed by RP-HPLC. Chlorophyll (Chl) and xanthophylls concentrations, together with ESR and real time PCR measurements, were also performed to get a complete overview of all photosystem changes. Cd only accumulated in basal leaves, that therefore were prevalently investigated for assessment of Cd induced changes. Here, Cd strongly reduced Chl concentration, especially Chl a. During the first 15 days of treatment, native electrophoresis system revealed high sensitivity of PSI to Cd, while minor effects on PSII were observed. Cytochrome b(6)/f and the ATP-synthase complex did not change following the Cd treatment. A significant reduction of antenna proteins of PSI was observed, while PSII antennae were affected to a minor extent, with exception of the isomeric Lhcb1.1 which decreased significantly already at the onset of the treatment. Some PSII core proteins were overexpressed, but showed reduced activity. No new protein was formed and no specific protein disappeared in the photosynthetic apparatus of Cd-treated leaves. Upon removal of Cd, a rapid resynthesis of total Chl and a significant resynthesis of Lhcb1.1 antenna were observed, suggesting that Cd affects specifically the photosynthetic apparatus of spinach basal leaves, replacing other metal ions inside proteins.

Comparative proteomics and transcriptomics analyses of livers from two different Bos taurus breeds: "Chianina and Holstein Friesian".

The Holstein Friesian and Chianina cattle breeds are representative of extreme selection for milk and meat traits, respectively, with significant changes in metabolism resulting from human selection over the past centuries. In the present study, we wanted to assess whether selection for different purposes has had a measurable effect on liver metabolism through a comparison of the protein and gene expression profiles of the two breeds. We applied 2-DE in order to identify proteins which were differentially expressed in the livers of the two breeds and relate them to different liver functions. We expected to find that only a small number of proteins would be differentially expressed, due to the relatively short phylogenetic distance between these cattle breeds. Nonetheless, thirty nine differentially-expressed proteins were characterized between Chianina and Holstein Friesian, out of a total of 560+/-57 spots that matched. Microarray analyses evidenced the differential expression of 167 genes (148 for the Holstein Friesian and 19 for the Chianina). Despite being closely related at the genetic level, the disparity of the proteomic and transcriptomic profiles of these two breeds allows us to perform pathway analysis thus to pinpoint proteins whose expression might render the latter capable of greater milk production, or proteins involved in altered thermoregulatory ability or hormone production. On the other hand, we found proteins and gene transcripts in Chianina, not expressed in Holstein, which, upon interaction pathway analysis, were mainly involved in anabolic pathways. In brief, our integrated study provides molecular evidences to support the physiological differences between Holstein and Chianina cattle breeds.

Coupling of Native Liquid Phase Isoelectrofocusing and Blue Native Polyacrylamide Gel Electrophoresis: A Potent Tool for Native Membrane Multiprotein Complex Separation

In this study, a new 3D native electrophoretic protocol is proposed for an exhaustive separation and identification of membrane proteins. It is based on native liquid phase isoelectrofocusing (N-LP-IEF) of protein complexes in the first dimension, followed by blue native polyacrylamide gel electrophoresis (BN-PAGE) in the second dimension, where both the pI and the molecular masses of protein complexes (2D N-LP-IEF-BN) were used to separate them in their native form. Finally, each single component can be resolved using denaturing electrophoresis (3D N-LP-IEF-BN-SDS-PAGE). The thylakoid membrane of spinach which contains four big protein complexes was chosen as a model for setting up analytical methods suitable for any membrane proteins. The pI-based MicroRotofor has a number of advantages over BN-PAGE: it does not require the addition of any chemicals, and separation of complexes is based on the proteins real physicochemical properties which inevitably change when dye is added. Results were more easily reproduced than with BN, and the pI of each native complex was also determined. Although some fractions still contained comigrating complexes after MicroRotofor, these were subsequently separated by BN for further analysis. Thus, highly hydrophobic complexes, such as ATP-synthetas and Cyt b6/f, were separated in native form as were various complexes of LHCII trimers, which have different pI but similar molecular masses. SDS-PAGE revealed almost all the subunits from the four photosynthetic complexes, indicating that by using 3D N-LP-IEF-BN-SDS-PAGE it is possible to achieve a greater degree of component identification than with 2D BN-SDS-PAGE.

Transfusion medicine in the era of proteomics

Blood components (BCs) are highly complex mixtures of plasma proteins and cells. At present, BC and blood derivatives (BDs) quality control is mainly focused on standardized quantitative assessment, providing relatively limited information about products. Unfortunately, during the production, inactivation, and storage processes there is the risk of changes in their integrity, especially at the protein level, which could cause negative effects on transfusion. It is therefore a major challenge to identify significant alterations of these products, and, in this context, proteomics can play a potentially relevant role in transfusion medicine (TM) to assess the protein composition of blood-derived therapeutics, particularly for identifying modified proteins. It can provide comprehensive information about changes occurring during processing and storage of BCs and BDs and can be applied to assess or improve them, therefore potentially enabling a global assessment of processing, inactivation and storage methods, as well as of possible contaminants and neoantigens that may influence the immunogenic capacity of blood-derived therapeutics. Thus, proteomics could become a relevant part of quality-control process to verify the identity, purity, safety, and potency of various blood therapeutics. A more detailed understanding of the proteins found in blood and blood products, and the identification of their interactions, may also yield important information for the design of new small molecule therapeutics and also for future improvements in TM. Proteomics, together with genomics in the near future, will presumably have an impact on disease diagnosis and prognosis as well as on further advances in the production, pathogen inactivation and storage processes of blood-based therapeutics.

Red blood cell processing for cryopreservation: from fresh blood to deglycerolization.

BACKGROUND Cryostorage of red blood cells (RBCs) represents a valid alternative to liquid storage, since units can be preserved safely for at least a decade while conserving RBC viability. While cryostorage has attracted a great deal of attention clinically, little is known about the biochemistry and physiology of cryostored erythrocyte concentrates. STUDY DESIGN AND METHOD In the present study, we investigated cryostorage of RBCs through monitoring of cell processing steps (from fresh blood, to glycerolization, thawing and deglycerolization/washing) through repeated assays of standard parameters (MCV, RDW-SD) and scanning electron microscopy. RESULTS Cell processing for cryostorage resulted in increased RBC volumes. Shape alterations caused an increase in osmotic fragility and permeability to ions. A significant pH drop was observed which could not to be attributed to a higher metabolic rate, since the levels of lactate did not show substantial fluctuation during the cell processing steps tested in this study. Membrane anomalies are likely related to the hemolysis observed which preferentially affected the densest and oldest cell sub-populations, as confirmed by means of discontinuous density gradients. CONCLUSION Our results indicate that cryostorage itself in presence of glycerol does not significantly affect RBCs. Most of the alterations observed were related to cell processing and, in particular, to the increase of cytosolic glycerol as a consequence of the glycerolyzation step. Further studies might profitably investigate replacing glycerol with non-penetrating cryoprotectants.

Plasma gelsolin protein: a candidate biomarker for hepatitis B-associated liver cirrhosis identified by proteomic approach

BACKGROUND Despite the significant improvement in internal medicine and supportive therapy in recent years, liver fibrosis/cirrhosis remains a serious health issue in hepatitis B virus (HBV) infected patients. Invasive liver biopsy is presently the best means of diagnosing cirrhosis, but it carries a significant risk and has well recognised limitations such as sampling error, hence the importance in developing early diagnosis biomarkers. With this aim, we performed a pilot proteomic study to assess this as a strategy for plasma marker detection in patients suffering from HBV-associated liver cirrhosis. METHODS Plasma from eight chronic HBV-infection patients and from eight HBV-related cirrhotic patients were selected and proteome profiles were created by two-dimensional electrophoresis. The strategy included the use of ProteoMiner enrichment kit for the reduction of highly abundance proteins (e.g. albumin and IgG) prior to proteomic analyses with the goal to improve detection of novel candidate markers. RESULTS One reproducible spot was found to be completely repressed in plasma samples from cirrhotic patients and mass spectrometry analysis identified this a specific variant of the gelsolin actin-depolymerizing factor. Though further investigations are needed, especially in term of clinical validation, to our knowledge this is the first time that gelsolin is proposed as potential biomarker in HBV-related liver pathologies. CONCLUSIONS Our findings confirm the potential utility of gelsolin either as a prognostic marker or a replacement therapeutic agent to alleviate liver injury.

Depletion of hemoglobin and carbonic anhydrase from erythrocyte cytosolic samples by preparative clear native electrophoresis

Proteomic analysis of red cells is compromised by the presence of high-abundance proteins (hemoglobin and carbonic anhydrase-1), which completely obscure low-abundance species. The depletion method presented here involves performing native gel electrophoresis in a polyacrylamide gel tube using a modified electroelution cell. The electrophoretic run is interrupted intermittently to allow the recovery of at least three different liquid fractions, which can be analyzed by both native PAGE and 2D isoelectric focusing SDS-PAGE, or by shotgun mass spectrometry analysis after trypsin in-solution protein digestion. This low-cost, reproducible technique can be used to process large amounts of sample, and it increases the likelihood of detecting low-abundance proteins, thereby resulting in greater proteome coverage. The separation procedure takes approximately 6–7 h.

Recombinant clotting factor VIII concentrates: Heterogeneity and high-purity evaluation

Factor VIII is an important glycoprotein involved in hemostasis. Insertion of expression vectors containing either the full‐length cDNA sequence of human factor VIII (FLrFVIII) or B‐domain deleted (BDDrFVIII) into mammalian cell lines results in the production of recombinant factor VIII (rFVIII) for therapeutic usage. Three commercially available rFVIII concentrates (Advate®, Helixate NexGen® and Refacto®), either FLrFVIII or BDDrFVIII, were investigated by 1‐ and 2‐DE and MS. The objective of this study was to compare the heterogeneity and the high purity of both rFVIII preparations before and after thrombin digestion. In particular, the 2‐D gel was optimized to better highlight the presence of contaminants and many unexpected proteins. Recombinant strategies consisting of insertion of expression vectors containing BDDrFVIII and FLrFVIII resulted in homogeneous and heterogeneous protein products, respectively, the latter consisting in a heterogeneous mixture of various B‐domain‐truncated forms of the molecule. Thrombin digestion of all the three rFVIII gave similar final products, plus one unexpected fragment of A2 domain missing 11 amino acids. Regarding the contaminants, Helixate NexGen® showed the presence of impurities, such as Hsp70 kDa, haptoglobin and proapolipoprotein; Refacto® showed glutathione S‐transferase and β‐lactamase, whereas Advate® apparently did not contain any contaminants. The proteomic approach will contribute to improving the quality assurance and manufacturing processes of rFVIII concentrates. In this view, the 2‐DE is mandatory for revealing the presence of contaminants.