Apolipoprotein J/Clusterin is a novel structural component of human erythrocytes and a biomarker of cellular stress and senescence

Aqueous humor perturbations in chronic smokers: a proteomic study

The detrimental effects of smoking are multisystemic and its effects on the eye health are significant. Smoking is a strong risk factor for age-related nuclear cataract, age-related macular degeneration, glaucoma, delayed corneal epithelial healing and increased risk of cystoid macular edema in patients with intermediate uveitis among others. We aimed to characterize the aqueous humor (AH) proteome in chronic smokers to gain insight into its perturbations and to identify potential biomarkers for smoking-associated ocular pathologies. Compared to the control group, chronic smokers displayed 67 (37 upregulated, 30 downregulated) differentially expressed proteins (DEPs). Analysis of DEPs from the biological point of view revealed that they were proteins involved in complement activation, lymphocyte mediated immunity, innate immune response, cellular oxidant detoxification, bicarbonate transport and platelet degranulation. From the molecular function point of view, DEPs were involved in oxygen binding, oxygen carrier activity, hemoglobin binding, peptidase/endopeptidase/cysteine-type endopeptidase inhibitory activity. Several of the upregulated proteins were acute phase reactant proteins such as clusterin, alpha-2-HS-glycoprotein, fibrinogen, alpha-1-antitrypsin, C4b-binding protein and serum amyloid A-2. Further research should confirm if these proteins might serve as biomarkers or therapeutic target for smoking-associated ocular diseases.

Simultaneous quantification of apolipoproteins A-I, E, and J in human plasma by LC-MS/MS for clinical application to diabetes mellitus complicated with cardiovascular disease

Apolipoproteins (Apos) play an important role in regulating plasma lipid concentration. Complex disorders of Apos are highly related with diabetes mellitus, cardiovascular and other diseases. Direct measures of lipoprotein fractions for risk assessment suffer from inaccuracy in the dyslipidemia and pathological states. Therefore, a reliable precise assay will be of high clinical utility. LC-MS/MS methods with multiple reaction monitoring modes have proven suitable for multiplexed quantification. We aimed to develop a simple, cost-effective and amenable LC-MS/MS assay for quantification of ApoA-I, ApoE and ApoJ in human plasma. Standards were constructed from substitute matrix and proteotypic peptides for external calibration and corresponding stable isotope labeled peptides were added as internal standards to remove matrix effects. Analytical validation of the assay included the assessment of linearity, accuracy (RE: −3.02% to 5.32%), intra-assay precision (RSD: 2.50% to 6.56%), inter-assay precision (RSD: 0.78% to 6.68%), spiking recovery rate (accuracy: 87.17% to 112.71%), matrix effect (accuracy: 88.03% to 114.87%), and reproducibility and repeatability of sample preparation (RSD: 1.95% to 7.26%). The performance of proteotypic peptides ApoA-I, ApoE and ApoJ was sufficient for triplex quantitation within a linear range from 16.26 to 1626.41 pmol mL⁻¹, 1.03 to 103.35 pmol mL⁻¹ and 0.86 to 86.46 pmol mL⁻¹ respectively. For all quantified peptides, the determination coefficient (R²) was >0.997. Besides, the validated LC-MS/MS method has been successfully applied to the quantification of plasma samples in diabetes mellitus and cardiovascular diseases. We anticipate that this assay may provide an alternative method for future clinical applications.

Simultaneous quantification of apolipoproteins A-I, E, and J in human plasma by LC-MS/MS.

RNA aptamers specific for transmembrane p24 trafficking protein 6 and Clusterin for the targeted delivery of imaging reagents and RNA therapeutics to human β cells

The ability to detect and target β cells in vivo can substantially refine how diabetes is studied and treated. However, the lack of specific probes still hampers a precise characterization of human β cell mass and the delivery of therapeutics in clinical settings. Here, we report the identification of two RNA aptamers that specifically and selectively recognize mouse and human β cells. The putative targets of the two aptamers are transmembrane p24 trafficking protein 6 (TMED6) and clusterin (CLUS). When given systemically in immune deficient mice, these aptamers recognize the human islet graft producing a fluorescent signal proportional to the number of human islets transplanted. These aptamers cross-react with endogenous mouse β cells and allow monitoring the rejection of mouse islet allografts. Finally, once conjugated to saRNA specific for X-linked inhibitor of apoptosis (XIAP), they can efficiently transfect non-dissociated human islets, prevent early graft loss, and improve the efficacy of human islet transplantation in immunodeficient in mice.

HDL Accessory Proteins in Parkinson’s Disease—Focusing on Clusterin (Apolipoprotein J) in Regard to Its Involvement in Pathology and Diagnostics—A Review

Parkinson’s disease (PD)—a neurodegenerative disorder (NDD) characterized by progressive destruction of dopaminergic neurons within the substantia nigra of the brain—is associated with the formation of Lewy bodies containing mainly α-synuclein. HDL-related proteins such as paraoxonase 1 and apolipoproteins A1, E, D, and J are implicated in NDDs, including PD. Apolipoprotein J (ApoJ, clusterin) is a ubiquitous, multifunctional protein; besides its engagement in lipid transport, it modulates a variety of other processes such as immune system functionality and cellular death signaling. Furthermore, being an extracellular chaperone, ApoJ interacts with proteins associated with NDD pathogenesis (amyloid β, tau, and α-synuclein), thus modulating their properties. In this review, the association of clusterin with PD is delineated, with respect to its putative involvement in the pathological mechanism and its application in PD prognosis/diagnosis.

Study on the Mechanism of Platelet-Released Clusterins Inducing Restenosis after Carotid Endarterectomy by Activating TLR3/NF-κb p65 Signaling Pathway

This study aimed to explore the role of clusterin released by platelet aggregation in restenosis after carotid endarterectomy. 35 patients who underwent carotid endarterectomy due to carotid artery stenosis were enrolled in this study. They were admitted to the Third Affiliated Hospital of Qiqihar Medical University from January 2018 to January 2019. All the patients were divided into two groups: the restenosis group and the nonrestenosis group, according to the follow-up results within 12 months. Peripheral blood was collected on the first day, 6 months, and 12 months after operation. The expression of CLU in serum of plasma and platelet culture medium was detected by an ELISA experiment. The vascular endothelial cells were cultured in vitro with 100 ng/mL of human recombinant CLU added to the medium. Cell proliferation, migration, and invasion were detected by CCK8, scratch, and Transwell invasion tests. The expression level of TLR3 and NF-κb p65 proteins in cells was detected by western blot. TLR3 knockout plasmids in vascular endothelial cell lines were transfected. Cell proliferation and migration were detected by CCK8 and the scratch assay. The CLU content in peripheral blood plasma and supernatant of platelet culture medium was significantly higher in the restenosis group than that of the control group (p=0.003) 6 months after operation (p=0.047) and 12 months after operation (p=0.011). When CLU was added to vascular endothelial cell culture medium, the proliferation and migration were significantly enhanced. The TLR3/NF-κb p65 protein expression level in cells also significantly increased. After the transfection of TLR3 knockout plasmids into vascular endothelial cell lines, CLU cannot promote the proliferation and migration of vascular endothelial cells. Platelet-released clusterin can induce vascular endothelial cell proliferation and migration by activating the TLR3/NF-kb p65 signaling pathway, leading to carotid artery restenosis after carotid endarterectomy.

Current Understanding of the Relationship between Blood Donor Variability and Blood Component Quality

While differences among donors has long challenged meeting quality standards for the production of blood components for transfusion, only recently has the molecular basis for many of these differences become understood. This review article will examine our current understanding of the molecular differences that impact the quality of red blood cells (RBC), platelets, and plasma components. Factors affecting RBC quality include cytoskeletal elements and membrane proteins associated with the oxidative response as well as known enzyme polymorphisms and hemoglobin variants. Donor age and health status may also be important. Platelet quality is impacted by variables that are less well understood, but that include platelet storage sensitive metabolic parameters, responsiveness to agonists accumulating in storage containers and factors affecting the maintenance of pH. An increased understanding of these variables can be used to improve the quality of blood components for transfusion by using donor management algorithms based on a donors individual molecular and genetic profile.

Clusterin and Its Role in Insulin Resistance and the Cardiometabolic Syndrome

The cardiometabolic syndrome involves a clustering of metabolic and cardiovascular factors which increase the risk of patients developing both Type 2 Diabetes Mellitus and cardio/cerebrovascular disease. Although the mechanistic underpinnings of this link remain uncertain, key factors include insulin resistance, excess visceral adiposity, atherogenic dyslipidemia, and endothelial dysfunction. Of these, a state of resistance to insulin action in overweight/obese patients appears to be central to the pathophysiologic process. Given the increasing prevalence of obesity-related Type 2 Diabetes, coupled with the fact that cardiovascular disease is the number one cause of mortality in this patient population, a more thorough understanding of the cardiometabolic syndrome and potential options to mitigate its risk is imperative. Inherent in the pathogenesis of insulin resistance is an underlying state of chronic inflammation, at least partly in response to excess adiposity. Within obese adipose tissue, an immunomodulatory shift occurs, involving a preponderance of pro-inflammatory immune cells and cytokines/adipokines, along with antigen presentation by adipocytes. Therefore, various adipokines differentially expressed by obese adipocytes may have a significant effect on cardiometabolism. Clusterin is a molecular chaperone that is widely produced by many tissues throughout the body, but is also preferentially overexpressed by obese compared lean adipocytes and relates strongly to multiple components of the cardiometabolic syndrome. Herein, we summarize the known and potential roles of circulating and adipocyte-specific clusterin in cardiometabolism and discuss potential further investigations to determine if clusterin is a viable target to attenuate both metabolic and cardiovascular disease.

Nicotine exposure increases markers of oxidant stress in stored red blood cells from healthy donor volunteers

BACKGROUND

Cigarette smoking is a frequent habit across blood donors (approx. 13% of the donor population), that could compound biologic factors and exacerbate oxidant stress to stored red blood cells (RBCs).

STUDY DESIGN AND METHODS

As part of the REDS-III RBC-Omics (Recipient Epidemiology Donor Evaluation Study III Red Blood Cell-Omics) study, a total of 599 samples were sterilely drawn from RBC units stored under blood bank conditions at Storage Days 10, 23, and 42 days, before testing for hemolysis parameters and metabolomics. Quantitative measurements of nicotine and its metabolites cotinine and cotinine oxide were performed against deuterium-labeled internal standards.

RESULTS

Donors whose blood cotinine levels exceeded 10 ng/mL (14% of the tested donors) were characterized by higher levels of early glycolytic intermediates, pentose phosphate pathway metabolites, and pyruvate-to-lactate ratios, all markers of increased basal oxidant stress. Consistently, increased glutathionylation of oxidized triose sugars and lipid aldehydes was observed in RBCs donated by nicotine-exposed donors, which were also characterized by increased fatty acid desaturation, purine salvage, and methionine oxidation and consumption via pathways involved in oxidative stress-triggered protein damage-repair mechanisms.

CONCLUSION

RBCs from donors with high levels of nicotine exposure are characterized by increases in basal oxidant stress and decreases in osmotic hemolysis. These findings indicate the need for future clinical studies aimed at addressing the impact of smoking and other sources of nicotine (e.g., nicotine patches, snuff, vaping, secondhand tobacco smoke) on RBC storage quality and transfusion efficacy.

Ethyl glucuronide, a marker of alcohol consumption, correlates with metabolic markers of oxidant stress but not with hemolysis in stored red blood cells from healthy blood donors

BACKGROUND

Red blood cell (RBC) storage in the blood bank is associated with the progressive accumulation of oxidant stress. While the mature erythrocyte is well equipped to cope with such stress, recreative habits like alcohol consumption may further exacerbate the basal level of oxidant stress and contribute to the progress of the storage lesion.

STUDY DESIGN AND METHODS

RBC levels of ethyl glucuronide, a marker of alcohol consumption, were measured via ultra-high-pressure liquid chromatography coupled with high-resolution mass spectrometry. Analyses were performed on 599 samples from the recalled donor population at Storage Days 10, 23, and 42 (n = 250), as part of the REDS-III RBC-Omics (Recipient Epidemiology Donor Evaluation Study III Red Blood Cell-Omics) study. This cohort consisted of the 5th and 95th percentile of donors with extreme hemolytic propensity out of the original cohort of 13,403 subjects enrolled in the REDS-III RBC Omics study. Ehtyl glucuronide levels were thus correlated to global metabolomics and lipidomics analyses and RBC hemolytic propensity.

RESULTS

Ethyl glucuronide levels were positively associated with oxidant stress markers, including glutathione consumption and turnover, methionine oxidation, S-adenosylhomocysteine accumulation, purine oxidation, and transamination markers. Decreases in glycolysis and energy metabolism, the pentose phosphate pathway and ascorbate system were observed in those subjects with the highest levels of ethyl glucuronide, though hemolysis values were comparable between groups.

CONCLUSION

Though preliminary, this study is suggestive that markers of alcohol consumption are associated with increases in oxidant stress and decreases in energy metabolism with no significant impact on hemolytic parameters in stored RBCs from healthy donor volunteers.

Hypoxic storage of red blood cells improves metabolism and post-transfusion recovery

BACKGROUND

Blood transfusion is a lifesaving intervention for millions of recipients worldwide every year. Storing blood makes this possible but also promotes a series of alterations to the metabolism of the stored erythrocyte. It is unclear whether the metabolic storage lesion is correlated with clinically relevant outcomes and whether strategies aimed at improving the metabolic quality of stored units, such as hypoxic storage, ultimately improve performance in the transfused recipient.

STUDY DESIGN AND METHODS

Twelve healthy donor volunteers were recruited in a two-arm cross-sectional study, in which each subject donated 2 units to be stored under standard (normoxic) or hypoxic conditions (Hemanext technology). End-of-storage measurements of hemolysis and autologous posttransfusion recovery (PTR) were correlated to metabolomics measurements at Days 0, 21, and 42.

RESULTS

Hypoxic red blood cells (RBCs) showed superior PTR and comparable hemolysis to donor-paired standard units. Hypoxic storage improved energy and redox metabolism (glycolysis and 2,3-diphosphoglycerate), improved glutathione and methionine homeostasis, decreased purine oxidation and membrane lipid remodeling (free fatty acid levels, unsaturation and hydroxylation, acyl-carnitines). Intra- and extracellular metabolites in these pathways (including some dietary purines) showed significant correlations with PTR and hemolysis, though the degree of correlation was influenced by sulfur dioxide (SO₂ ) levels.

CONCLUSION

Hypoxic storage improves energy and redox metabolism of stored RBCs, which results in improved posttransfusion recoveries in healthy autologous recipients-a Food and Drug Administration gold standard of stored blood quality. In addition, we identified candidate metabolic predictors of PTR for RBCs stored under standard and hypoxic conditions.

Parabiosis Incompletely Reverses Aging-Induced Metabolic Changes and Oxidant Stress in Mouse Red Blood Cells

Mature red blood cells (RBCs) not only account for ~83% of the total host cells in the human body, but they are also exposed to all body tissues during their circulation in the bloodstream. In addition, RBCs are devoid of de novo protein synthesis capacity and, as such, they represent a perfect model to investigate system-wide alterations of cellular metabolism in the context of aging and age-related oxidant stress without the confounding factor of gene expression. In the present study, we employed ultra-high-pressure liquid chromatography coupled with mass spectrometry (UHPLC–MS)-based metabolomics and proteomics to investigate RBC metabolism across age in male mice (6, 15, and 25 months old). We report that RBCs from aging mice face a progressive decline in the capacity to cope with oxidant stress through the glutathione/NADPH-dependent antioxidant systems. Oxidant stress to tryptophan and purines was accompanied by declines in late glycolysis and methyl-group donors, a potential compensatory mechanism to repair oxidatively damaged proteins. Moreover, heterochronic parabiosis experiments demonstrated that the young environment only partially rescued the alterations in one-carbon metabolism in old mice, although it had minimal to no impact on glutathione homeostasis, the pentose phosphate pathway, and oxidation of purines and tryptophan, which were instead aggravated in old heterochronic parabionts.

Protect, repair, destroy or sacrifice: a role of oxidative stress biology in inter-donor variability of blood storage?

Red blood cells (RBCs) have been historically regarded as a critical model to investigate cellular and oxidant stress biology. First of all, they are constantly exposed to oxidant stress, as their main function is to transport and deliver oxygen to tissues. Second, they are devoid of de novo protein synthesis capacity, which prevents RBCs from replacing irreversibly oxidised proteins with newly synthesised ones. As such, RBCs have evolved to (i) protect themselves from oxidant stress, in order to prevent oxidant damage from reactive species; (ii) repair oxidatively damaged proteins, through mechanisms that involve glutathione and one-carbon metabolism; (iii) destroy irreversibly oxidised proteins through proteasomal or protease-dependent degradation; and (iv) sacrifice membrane portions through mechanism of vesiculation. In this brief review we will summarize these processes and their relevance to RBC redox biology (within the context of blood storage), with a focus on how polymorphisms in RBC antioxidant responses could contribute to explaining the heterogeneity in the progression and severity of the RBC storage lesion that can be observed across the healthy donor population.

Disturbed Red Blood Cell Structure and Function: An Exploration of the Role of Red Blood Cells in Neurodegeneration

The structure of red blood cells is affected by many inborn and acquired factors, but in most cases this does not seem to affect their function or survival in physiological conditions. Often, functional deficits become apparent only when they are subjected to biochemical or mechanical stress in vitro, or to pathological conditions in vivo. Our data on the misshapen red blood cells of patients with neuroacanthocytosis illustrate this general mechanism: an abnormal morphology is associated with an increase in the susceptibility of red blood cells to osmotic and mechanical stress, and alters their rheological properties. The underlying mutations may not only affect red cell function, but also render neurons in specific brain areas more susceptible to a concomitant reduction in oxygen supply. Through this mechanism, an increased susceptibility of already compromised red blood cells to physiological stress conditions may constitute an additional risk factor in vulnerable individuals. Also, susceptibility may be induced or enhanced by systemic pathological conditions such as inflammation. An exploration of the literature suggests that disturbed red blood cell function may play a role in the pathophysiology of various neurodegenerative diseases. Therefore, interventions that reduce the susceptibility of red blood cells to physiological and pathological stress may reduce the extent or progress of neurodegeneration.

Apolipoprotein J as a predictive biomarker for restenosis after carotid endarterectomy: a retrospective study

Carotid endarterectomy (CEA) is an effective surgical option for stroke prophylaxis in most patients. Restenosis after CEA can lead to re-intervention and adverse events, but the factors predicting restenosis are poorly understood. Apolipoprotein J (ApoJ) is considered to be a novel predictive factor of vascular restenosis and is associated with a large number of processes related to atherosclerosis and cell-cycle phases. The aim of this study was to elucidate the predictive value of Apo J in internal carotid artery (ICA) restenosis following CEA. This retrospective study examined all prospectively collected data for patients who underwent CEA at our surgical department over a 2-year period. The serum ApoJ levels of 100 patients were examined; 56 patients who underwent CEA comprised the vascular group (VG), and 44 patients who underwent minor surgery comprised the control group (CG). ApoJ samples were obtained preoperatively, 24 h after the surgical procedure and at 1, 6 and 12 months thereafter during the follow-up. The preoperative difference in ApoJ levels between the CG and VG was statistically signifcant; the mean values were 39.11±14.16 and 83.03±35.35 μg/mL, respectively. In the VG, the serum ApoJ levels were 112.09±54.40, 71.20±23.70, 69.92±25.76 and 62.25±19.17 μg/mL at postoperative day 1 and at 1, 6 and 12 months post-operatively, respectively, while the ApoJ concentrations of patients in the CG remained unchanged. Further subdivision of the VG into patients with or without restenosis revealed that restenosis patients presented signifcantly higher mean ApoJ values than non-restenosis VG patients. In summary, ApoJ seems to be an important predictor for carotid restenosis at 6 and 12 months postoperatively.

Development of a Label-Free Immunosensor for Clusterin Detection as an Alzheimer's Biomarker

Clusterin (CLU) has been associated with the clinical progression of Alzheimer's disease (AD) and described as a potential AD biomarker in blood plasma. Due to the enormous attention given to cerebrospinal fluid (CSF) biomarkers for the past couple of decades, recently found blood-based AD biomarkers like CLU have not yet been reported for biosensors. Herein, we report the electrochemical detection of CLU for the first time using a screen-printed carbon electrode (SPCE) modified with 1-pyrenebutyric acid N-hydroxysuccinimide ester (Pyr-NHS) and decorated with specific anti-CLU antibody fragments. This bifunctional linker molecule contains succinylimide ester to bind protein at one end while its pyrene moiety attaches to the carbon surface by means of π-π stacking. Cyclic voltammetric and square wave voltammetric studies showed the limit of detection down to 1 pg/mL and a linear concentration range of 1-100 pg/mL with good sensitivity. Detection of CLU in spiked human plasma was demonstrated with satisfactory recovery percentages to that of the calibration data. The proposed method facilitates the cost-effective and viable production of label-free point-of-care devices for the clinical diagnosis of AD.

Antibodies to Senescent Antigen and C3 Are Not Required for Normal Red Blood Cell Lifespan in a Murine Model

Red blood cells (RBCs) have a well-defined lifespan, indicating a mechanism by which senescent cells of a certain age are removed from circulation. However, the specifics by which senescent cells are recognized and removed are poorly understood. There are multiple competing hypotheses for this process, perhaps the most commonly cited is that senescent RBCs expose neoantigens [or senescent antigen(s)] that are then recognized by naturally occurring antibodies, which opsonize the senescent cells and result in clearance from circulation. While there are a large volume of published data to indicate that older RBCs accumulate increased levels of antibody on their surface, to the best of our knowledge, the causal role of such antibodies in clearance has not been rigorously assessed. In the current report, we demonstrate that RBC lifespan and clearance patterns are not altered in mice deficient in antibodies, in C3 protein, or missing both. These data demonstrate that neither antibody nor C3 is required for clearance of senescent RBCs, and questions if they are even involved, in a murine model of RBC lifespan.

Understanding quasi-apoptosis of the most numerous enucleated components of blood needs detailed molecular autopsy

Erythrocytes are the most numerous cells in human body and their function of oxygen transport is pivotal to human physiology. However, being enucleated, they are often referred to as a sac of molecules and their cellularity is challenged. Interestingly, their programmed death stands a testimony to their cell-hood. They are capable of self-execution after a defined life span by both cell-specific mechanism and that resembling the cytoplasmic events in apoptosis of nucleated cells. Since the execution process lacks the nuclear and mitochondrial events in apoptosis, it has been referred to as quasi-apoptosis or eryptosis. Several studies on molecular mechanisms underlying death of erythrocytes have been reported. The data has generated a non-cohesive sketch of the process. The lacunae in the present knowledge need to be filled to gain deeper insight into the mechanism of physiological ageing and death of erythrocytes, as well as the effect of age of organism on RBCs survival. This would entail how the most numerous cells in the human body die and enable a better understanding of signaling mechanisms of their senescence and premature eryptosis observed in individuals of advanced age.

Donor-variation effect on red blood cell storage lesion: A close relationship emerges

Although the molecular pathways leading to the progressive deterioration of stored red blood cells (RBC storage lesion) and the clinical relevance of storage-induced changes remain uncertain, substantial donor-specific variability in RBC performance during storage, and posttransfusion has been established ("donor-variation effect"). In-bag hemolysis and numerous properties of the RBC units that may affect transfusion efficacy have proved to be strongly donor-specific. Donor-variation effect may lead to the production of highly unequal blood labile products even when similar storage strategy and duration are applied. Genetic, undiagnosed/subclinical medical conditions and lifestyle factors that affect RBC characteristics at baseline, including RBC lifespan, energy metabolism, and sensitivity to oxidative stress, are all likely to influence the storage capacity of individual donors' cells, although not evident by the donor's health or hematological status at blood donation. Consequently, baseline characteristics of the donors, such as membrane peroxiredoxin-2 and serum uric acid concentration, have been proposed as candidate biomarkers of storage quality. This review article focuses on specific factors that might contribute to the donor-variation effect and emphasizes the emerging need for using omics-based technologies in association with in vitro and in vivo transfusion models and clinical trials to discover biomarkers of storage quality and posttransfusion recovery in donor blood.

Apolipoprotein J: A New Predictor and Therapeutic Target in Cardiovascular Disease?

Objective:

To review the functional mechanism of apolipoprotein J (apoJ) in the process of atherosclerosis and the feasibility of apoJ as a therapeutic endpoint.

Data Sources:

Relevant articles published in English from 1983 to present were selected from PubMed. The terms of “atherosclerosis, apolipoprotein J, clusterin (CLU), oxidative stress, and inflammation” were used for searching.

Study Selection:

Articles studying the role of apoJ with atherosclerosis and restenosis after injury were reviewed. Articles focusing on the intrinsic determinants of atherosclerosis were selected. The exclusion criteria of articles were that the studies on immunologic vasculitis.

Results:

ApoJ, involved in numerous physiological process important for lipid transportation and vascular smooth muscle cell differentiation, including apoptotic cell death, cell-cycle regulation, cell adhesion, tissue remodeling, immune system regulation, and oxidative stress, plays a role in the development of clinical atherosclerosis. In the process of relieving atherosclerosis, apoJ can promote cholesterol and phospholipid export from macrophage-foam cells, and exhibit cytoprotective and anti-inflammatory actions by interacting with lots of known inflammatory proteins which may predict the onset of clinical cardiovascular events and may actually play a causal role in mediating atherosclerotic disease such as C-reactive protein, paraoxonase, and leptin. As known as CLU, apoJ has been identified to play central roles in the process of vascular smooth cells migration, adhesion, and proliferation, which can contribute significantly to restenosis after vascular injury.

Conclusions:

Intense effort and substantial progress have been made to identify the apoJ that relieves atherosclerosis and vascular restenosis after percutaneous coronary intervention. More work is needed to elucidate the exact mechanisms of and the interrelationship between the actions of apoJ and to successfully achieve regression of atherosclerosis by regarding it as a therapeutic endpoint.

Proteomic Profile of Unstable Atheroma Plaque: Increased Neutrophil Defensin 1, Clusterin, and Apolipoprotein E Levels in Carotid Secretome

Because of the clinical significance of carotid atherosclerosis, the search for novel biomarkers has become a priority. The aim of the present study was to compare the protein secretion profile of the carotid atherosclerotic plaque (CAP, n = 12) and nonatherosclerotic mammary artery (MA, n = 10) secretomes. We used a nontargeted proteomic approach that incorporated tandem immunoaffinity depletion, iTRAQ labeling, and nanoflow liquid chromatography coupled to high-resolution mass spectrometry. In total, 162 proteins were quantified, of which 25 showed statistically significant differences in secretome levels between carotid atherosclerotic plaque and nondiseased mammary artery. We found increased levels of neutrophil defensin 1, apolipoprotein E, clusterin, and zinc-alpha-2-glycoprotein in CAP secretomes. Results were validated by ELISA assays. Also, differentially secreted proteins are involved in pathways such as focal adhesion and leukocyte transendothelial migration. In conclusion, this study provides a subset of identified proteins that are differently expressed in secretomes of clinical significance.

Plasma biomarkers for neuronal ceroid lipofuscinosis

The neuronal ceroid lipofuscinoses (NCLs) are a group of neurodegenerative genetic diseases that primarily affect children and have no known cure. A unified clinical rating scale for the juvenile form of NCL has been developed, although it has not been validated in other subtypes and does not give a true measure of the pathophysiological changes occurring during disease progression. In the present study, we have identified candidate biomarkers in blood plasma of NCL disease using multiple proteomic approaches, with the aim of developing a panel of biomarkers that could serve as a metric for therapeutic response. Candidate biomarkers were identified as proteins with levels that significantly differed between patients and controls in both sample sets. The seven candidates identified have previously been associated with neurodegenerative and inflammatory diseases. Multiplex immunoassay based testing was the most efficient and effective evaluation technique and could be employed on a broad scale to track patient response to treatment.

Uric acid variation among regular blood donors is indicative of red blood cell susceptibility to storage lesion markers: A new hypothesis tested

BACKGROUND

Oxidative stress orchestrates a significant part of the red blood cell (RBC) storage lesion. Considering the tremendous interdonor variability observed in the "storability," namely, the capacity of RBCs to sustain the storage lesion, this study aimed at the elucidation of donor-specific factors that affect the redox homeostasis during the storage of RBCs in standard systems.

STUDY DESIGN AND METHODS

The hematologic profile of regular blood donors (n = 78) was evaluated by biochemical analysis of 48 different variables, including in vivo hemolysis and plasma oxidant and antioxidant factors and statistical analysis of the results. The possible effect of the uric acid (UA) variable on RBC storability was investigated in leukoreduced CPD/SAGM RBC units (n = 8) collected from donors exhibiting high or low prestorage levels of UA, throughout the storage period.

RESULTS

Among the hematologic variables examined in vivo, cluster analysis grouped the donors according to their serum UA levels. Plasma antioxidant capacity, iron indexes, and protein carbonylation represented covariants of UA factor. RBCs prepared by low- or high-UA donors exhibited significant differences between them in spheroechinocytosis, supernatant antioxidant activity, and other RBC storage lesion-associated variables.

CONCLUSION

UA exhibits a storability biomarker potential. Intrinsic variability in plasma UA levels might be related to the interdonor variability observed in the storage capacity of RBCs. A model for the antioxidant effect of UA during the RBC storage is currently proposed.

Clusterin/Apolipoprotein J immunolocalization on carotid artery is affected by TNF-alpha, cigarette smoking and anti-platelet treatment

Background

Clusterin (CLU) /Apolipoprotein J is a protein biosensor of oxidative stress and inflammation, which is upregulated in many pathological processes including atherosclerosis. Previous studies have shown that in aortic tissue, CLU expression increases with atherosclerotic lesion progression and it has been coupled with vascular damage and coronary artery disease. A few studies enter into CLU and carotid atherosclerosis while the apolipoprotein’s expression on human carotid tissue and its association with parameters related to the disease development has not been examined. The present study was designed to reveal the relationships between the degree of CLU immunolocalization on carotid artery and demographic characteristics, blood parameters and pharmacological treatment of patients underwent internal carotid artery endarterectomy.

Methods

CLU expression was detected by immunohistochemistry in 42 carotid endarterectomy specimens. Patients’ serum levels of tumor necrosis factor-a (TNF-a), interleukin-6 (IL-6), high sensitive C-reactive protein (hsCRP) and classical parameters related to atherosclerosis such as lipid profile, as well as thrombosis related parameters such as fibrinogen, antithrombin III, protein C and protein S were determined. Demographic characteristics, smoking habits and the use of medications were recorded. Comparisons between groups were performed by students’t-test and analysis of variance. Independent associations with CLU expression on carotid tissue were denoted by linear regression analysis.

Results

CLU imuunolocalization was denser in smokers than in non-smokers (p = 0.041) while it was rarefied in specimens of patients on cropidogrel treatment (p = 0.045) compared to the rest not taking this medication. Clopidogrel intake was independent predictor of lower CLU expression on carotid artery (p =0.045). CLU was positively correlated with serum TNF-a concentration (r = 0.33, p = 0.040) that was independent predictor of higher expression of the apolipoprotein (p = 0.001). IL-6, hsCRP and classical parameters related to atherosclerosis and thrombosis were not associated with CLU immunolocalization.

Conclusion

Our study suggests that CLU expression on carotid artery is affected by TNF-alpha, cigarette smoking confirming its association with oxidative and cellular stress and anti-platelet medication reflecting the protective effects of such pharmacological treatment on vascular wall.

Cell surface membrane proteins as personalized biomarkers: where we stand and where we are headed

Personalized medicine requires the development of a wide array of biomarker diagnostic assays, reflecting individual variations and thus allowing tailored therapeutic interventions. Membrane proteins comprise approximately 30% of total human proteins; they play a key role in various physiological functions and pathological conditions, although, currently, only a limited number of membrane proteins are applied as biomarkers. In many normal tissues, cell surface membrane proteins are not easily accessible for diagnostic sampling, and tumor-derived membrane preparations - while serving as potential tumor biomarkers - may not reflect physiological protein expression. In addition to post-translational modifications, which may include glycosylation, phosphorylation and lipid modifications, the trafficking of membrane proteins is also regulated. Moreover, a tight cellular quality control monitors membrane protein maturation, and continuous removal and reinsertion, involving special signaling systems, occurs in many cases. However, cell surface membrane proteins already serve as valuable prognostic and predicative biomarkers, for example, in hematological and immunological diseases, by the determination of the cluster of differentiation markers. In this review, we demonstrate the relevance of cell surface membrane biomarkers in various diseases and call attention to the potential application of red blood cell (erythrocyte) membrane proteins in this regard. Surprisingly, red blood cells express hundreds of membrane proteins, which seem to reflect a general genetic and regulatory background, and may serve as relatively stable and easily accessible personalized membrane biomarkers. Quantitative membrane protein detection in red blood cells by flow cytometry may bring a breakthrough in this regard.

The physiological roles of apolipoprotein J/clusterin in metabolic and cardiovascular diseases

Several isoforms of apolipoprotein J/clusterin (CLU) are encoded from a single gene located on chromosome 8 in humans. These isoforms are ubiquitously expressed in the tissues, and have been implicated in aging, neurodegenerative disorders, cancer progression, and metabolic/cardiovascular diseases including dyslipidemia, diabetes, atherosclerosis and myocardial infarction. The conventional secreted form of CLU (sCLU) is thought to be a component of high density lipoprotein-cholesterol. sCLU functions as a chaperone for misfolded proteins and it is thought to promote survival by reducing oxidative stress. Nuclear CLU, a truncated CLU formed by alternative splicing, is responsible for promoting apoptosis via a Bax-dependent pathway. There are putative regulatory sites in the promoter regions of CLU, which are occupied by transcription factors such as transforming growth factor (TGF)-β inhibitory element, activator protein-1, CLU-specific elements, and carbohydrate response element. However, the molecular mechanisms underlying the distinct roles of CLU in a variety of conditions remain unclear. Although the function of CLU in cancer or neurological disease has been studied intensively for three decades, physiological roles of CLU seem unexplored in the cardiovascular system and metabolic diseases. In this review, we will discuss general characteristics and regulations of CLU based on previous literature and assess the recent findings associated with its physiological roles in different tissues including the vasculature, heart, liver, kidney, adipose tissue, and brain.

The molecular chaperone apolipoprotein J/clusterin as a sensor of oxidative stress: implications in therapeutic approaches - a mini-review

BACKGROUND

Organisms are constantly exposed to physiological and environmental stresses and therefore require an efficient surveillance of genome and proteome quality in order to prevent disruption of homeostasis. Central to the intra- and extracellular proteome surveillance system are the molecular chaperones that contribute to both proteome maintenance and clearance. The conventional protein product of the apolipoprotein J/clusterin (CLU) gene is a heterodimeric secreted glycoprotein (also termed as sCLU) with a ubiquitous expression in human tissues. CLU exerts a small heat shock protein-like stress-induced chaperone activity and has been functionally implicated in numerous physiological processes as well as in ageing and most age-related diseases including tumorigenesis, neurodegeneration, and cardiovascular and metabolic syndromes.

OBJECTIVE

The CLU gene is differentially regulated by a wide variety of stimuli due to the combined presence of many distinct regulatory elements in its promoter that make it an extremely sensitive cellular biosensor of environmental and/or oxidative stress. Downstream to CLU gene induction, the CLU protein seems to actively intervene in pathological states of increased oxidative injury due to its chaperone-related property to inhibit protein aggregation and precipitation (a main feature of oxidant injury), as well as due to its reported distribution in both extra- and, most likely, intracellular compartments.

CONCLUSION

On the basis of these findings, CLU has emerged as a unique regulator of cellular proteostasis. Nevertheless, it seemingly exerts a dual function in pathology. For instance, in normal cells and during early phases of carcinogenesis, CLU may inhibit tumor progression as it contributes to suppression of proteotoxic stress. In advanced neoplasia, however, it may offer a significant survival advantage in the tumor by suppressing many therapeutic stressors and enhancing metastasis. This review will critically present a synopsis of recent novel findings that relate to the function of this amazing molecule and support the notion that CLU is a biosensor of oxidative injury; a common link between ageing and all pathologies where CLU has been implicated. Potential future perspectives, implications and opportunities for translational research and the development of new therapies will be discussed.

Decreased plasma levels of clusterin in patients with psoriasis

INTRODUCTION AND OBJECTIVES

Psoriasis is a chronic inflammatory disease that has been linked to increased cardiovascular risk. The glycoprotein clusterin (apolipoprotein J) is a component of high-density lipoproteins and has a protective role in atherosclerosis. The aim of the present study was to evaluate the plasma levels of clusterin and the proinflammatory cytokine macrophage migration inhibitory factor (MIF) in patients with severe psoriasis, comparing groups of patients with different risks of cardiovascular disease.

MATERIAL AND METHODS

Twenty-one patients with severe psoriasis (psoriasis area severity index and body surface area>10) and 11 healthy controls with no dermatologic disease were studied. Cardiovascular risk factors were assessed according to the Adult Treatment Panel (ATP) III criteria. Subclinical carotid atheromatosis was assessed by Doppler ultrasonography of the carotid arteries. Plasma clusterin and MIF levels were measured by enzyme-linked immunosorbent assay.

RESULTS

ATP-III criteria for metabolic syndrome were met by 47% of the patients, and 33% had carotid atheromatous plaque. Mean (SD) clusterin plasma levels were significantly lower in patients with psoriasis compared with controls (81.39 [27.30] μg/mL for the 21 patients vs 117 [21.6] μg/mL for the 11 controls; P=.0017). MIF plasma levels (ng/ml) were significantly higher in patients with atheromatous plaque compared with controls (53.22 [29.02] for the 6 patients with plaque vs 34.21 [9.65] for the 11 controls; P=.0394).

CONCLUSIONS

The decreased plasma levels of clusterin in psoriatic patients suggested an association with the disease and might be an indicator of systemic inflammatory activity. Increased levels of MIF appear to be associated with cardiovascular risk factors and carotid atheromatous plaque.

Effects of pre-storage leukoreduction on stored red blood cells signaling: a time-course evaluation from shape to proteome

The introduction of pre-storage leukoreduction in the preparation of standard RBCs intended for transfusion provided significant improvement in the quality of labile products and their post transfusion viability and effects, although the literature data are controversial. To elucidate the issue of the probable leukoreduction effects on RBCs storage lesion, we evaluated various storage quality measures in RBCs stored in either leukoreduced (L) or non-leukoreduced (N) units, with emphasis to senescence and oxidative stress associated modifications. Our data suggest that the residual leukocytes/platelets of the labile products represent a stressful storage factor, countering the structural and functional integrity of stored RBCs. Hemolysis, irreversible echinocytosis, microvesiculation, removal signaling, ROS/calcium accumulation, band 3-related senescence modifications, membrane proteome stress biomarkers as well as emergence of a senescence phenotype in young RBCs that is disproportionate to their age, are all encountered more or mostly in N-RBCs compared to the L-RBCs, either for a part or for the whole of the storage period. The partial, yet significant, alleviation of so many storage-related manifestations in the L-RBCs compared to the N-RBCs, is presented for the first time and provides a rational mechanistic interpretation of the improved storage quality and transfusions observed by the introduction of pre-storage leukoreduction. This article is part of a Special Issue entitled: Integrated omics.