Haptoglobin: old protein with new functions

Circulating biomarkers of airflow limitation across the life span

BACKGROUND

Airflow limitation is a hallmark of chronic obstructive pulmonary disease, which can develop through different lung function trajectories across the life span. There is a need for longitudinal studies aimed at identifying circulating biomarkers of airflow limitation across different stages of life.

OBJECTIVES

This study sought to identify a signature of serum proteins associated with airflow limitation and evaluate their relation to lung function longitudinally in adults and children.

METHODS

This study used data from 3 adult cohorts (TESAOD [Tucson Epidemiological Study of Airway Obstructive Disease], SAPALDIA [Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults], LSC [Lovelace Smoker Cohort]) and 1 birth cohort (TCRS [Tucson Children's Respiratory Study]) (N = 1940). In TESAOD, among 46 circulating proteins, we identified those associated with FEV1/forced vital capacity (FVC) percent (%) predicted levels and generated a score based on the sum of their z-scores. Cross-sectional analyses were used to test the score for association with concomitant lung function. Longitudinal analyses were used to test the score for association with subsequent lung function growth in childhood and decline in adult life.

RESULTS

After false discovery rate adjustment, serum levels of 5 proteins (HP, carcinoembryonic antigen, ICAM1, CRP, TIMP1) were associated with percent predicted levels of FEV1/FVC and FEV1 in TESAOD. In cross-sectional multivariate analyses the 5-biomarker score was associated with FEV1 % predicted in all adult cohorts (meta-analyzed FEV1 decrease for 1-SD score increase: -2.9%; 95% CI: -3.9%, -1.9%; P = 2.4 × 10-16). In multivariate longitudinal analyses, the biomarker score at 6 years of age was inversely associated with FEV1 and FEV1/FVC levels attained by young adult life (P = .02 and .005, respectively). In adults, persistently high levels of the biomarker score were associated with subsequent accelerated decline of FEV1 and FEV1/FVC (P = .01 and .001).

CONCLUSIONS

A signature of 5 circulating biomarkers of airflow limitation was associated with both impaired lung function growth in childhood and accelerated lung function decline in adult life, indicating that these proteins may be involved in multiple lung function trajectories leading to chronic obstructive pulmonary disease.

How We Interpret Thrombosis with Thrombocytopenia Syndrome?

Platelets play an important role in hemostasis, and a low platelet count usually increases the risk of bleeding. Conditions in which thrombosis occurs despite low platelet counts are referred to as thrombosis with thrombocytopenia syndrome, including heparin-induced thrombocytopenia, vaccine-induced immune thrombotic thrombocytopenia, paroxysmal nocturnal hemoglobinuria, antiphospholipid syndrome, thrombotic microangiopathy (TMA), and disseminated intravascular coagulation. TMA includes thrombotic thrombocytopenic purpura, Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (HUS), and atypical HUS. Patients with these pathologies present with thrombosis and consumptive thrombocytopenia associated with the activation of platelets and the coagulation system. Treatment varies from disease to disease, and many diseases have direct impacts on mortality and organ prognosis if therapeutic interventions are not promptly implemented. Underlying diseases and the results of physical examinations and general laboratory tests as part of a thorough workup for patients should promptly lead to therapeutic intervention before definitive diagnosis. For some diseases, the diagnosis and initial treatment must proceed in parallel. Utilization of not only laboratory tests but also various scoring systems is important for validating therapeutic interventions based on clinical information.

Identification of small molecules affecting the interaction between human hemoglobin and Staphylococcus aureus IsdB hemophore

Human hemoglobin (Hb) is the preferred iron source of Staphylococcus aureus. This pathogenic bacterium exploits a sophisticated protein machinery called Iron-regulated surface determinant (Isd) system to bind Hb, extract and internalize heme, and finally degrade it to complete iron acquisition. IsdB, the surface exposed Hb receptor, is a proven virulence factor of S. aureus and the inhibition of its interaction with Hb can be pursued as a strategy to develop new classes of antimicrobials. To identify small molecules able to disrupt IsdB:Hb protein-protein interactions (PPIs), we carried out a structure-based virtual screening campaign and developed an ad hoc immunoassay to screen the retrieved set of commercially available compounds. Saturation-transfer difference (STD) NMR was applied to verify specific interactions of a sub-set of molecules, chosen based on their efficacy in reducing the amount of Hb bound to IsdB. Among molecules for which direct binding was verified, the best hit was submitted to ITC analysis to measure the binding affinity to Hb, which was found to be in the low micromolar range. The results demonstrate the viability of the proposed in silico/in vitro experimental pipeline to discover and test IsdB:Hb PPI inhibitors. The identified lead compound will be the starting point for future SAR and molecule optimization campaigns.

Erythrocytes: Member of the Immune System that Should Not Be Ignored

Erythrocytes are the most abundant type of cells in the blood and have a relatively simple structure when mature; they have a long life-span in the circulatory system. The primary function of erythrocytes is as oxygen carriers; however, they also play an important role in the immune system. Erythrocytes recognize and adhere to antigens and promote phagocytosis. The abnormal morphology and function of erythrocytes are also involved in the pathological processes of some diseases. Owing to the large number and immune properties of erythrocytes, their immune functions should not be ignored. Currently, research on immunity is focused on immune cells other than erythrocytes. However, research on the immune function of erythrocytes and the development of erythrocyte-mediated applications is of great significance. Therefore, we aimed to review the relevant literature and summarize the immune functions of erythrocytes.

High-throughput immunoaffinity enrichment and N-glycan analysis of human plasma haptoglobin

Haptoglobin (Hp) is a positive acute phase protein, synthesized in the liver, with four N-glycosylation sites carrying mainly complex type N-glycans. Its glycosylation is altered in different types of diseases but still has not been extensively studied mainly due to analytical challenges, especially the lack of a fast, efficient, and robust high-throughput Hp isolation procedure. Here, we describe the development of a high-throughput method for Hp enrichment from human plasma, based on monolithic chromatographic support in immunoaffinity mode and downstream Hp N-glycome analysis by hydrophilic interaction ultrahigh-performance liquid chromatography with fluorescent detection (HILIC-UHPLC-FLR). Chromatographic monolithic supports in a 96-well format enable fast, efficient, and robust Hp enrichment directly from diluted plasma samples. The N-glycome analysis demonstrated that a degree of Hp deglycosylation differs depending on the conditions used for N-glycan release and on the specific glycosylation site, with Asn 241 being the most resistant to deglycosylation under tested conditions. HILIC-UHPLC-FLR analysis enables robust quantification of 28 individual chromatographic peaks, in which N-glycan compositions were determined by UHPLC coupled to electrospray ionization quadrupole time of flight mass spectrometry. The developed analytical approach enables fast evaluation of total Hp N-glycosylation and is applicable in large-scale studies.

Enniatin B and beauvericin affect intestinal cell function and hematological processes in Atlantic salmon (Salmo salar) after acute exposure

Unintentional use of mold-infested plant-based feed ingredients are sources of mycotoxins in fish feeds. The presence of the emerging mycotoxins ENNB and BEA in Norwegian commercial fish feeds and plant-based feed ingredients has raised concerns regarding the health effects on farmed Atlantic salmon (Salmon salar). Atlantic salmon pre-smolts were exposed to non-lethal doses of BEA and ENNB (ctrl, 50 and 500 μg/kg feed for 12 h), after which total RNA sequencing of the intestine and liver was carried out to evaluate gut health and identify possible hepatological changes after acute dietary exposure. ENNB and BEA did not trigger acute toxicity, however ENNB caused the onset of pathways linked to acute intestinal inflammation and BEA exposures caused the onset of hepatic hematological disruption. The prevalence and concentration of ENNB found in today's commercial feed could affect the fish health if consumed over a longer time-period.

Regional variations and relationships among cytokine profiles, white blood cell counts, and blood mercury concentrations in Steller sea lion (Eumetopias jubatus) pups

The Steller sea lion (SSL) population west of 144°W longitude experienced a significant population decline. While there appears to be a stable or increasing population trend in rookeries in the Gulf of Alaska (GOA) and Southeast Alaska (SEA), some rookeries within the Aleutian Islands (AI) have failed to recover. Previous studies found regional differences in whole blood total mercury concentrations ([THg]) showing more than 20% of AI pups had [THg] above critical thresholds for increased risk of immunological effects and other adverse outcomes. Measurements of immune cell-signaling proteins can be used to evaluate the immune status of marine mammals in relation to [THg]. We compared serum cytokine and chemokine concentrations in pups among regions (AI, eastern GOA, SEA), and examined associations among cytokines, chemokines, white blood cell (WBC) counts, and [THg]. Considering liver is an important target organ for mercury and immune protein synthesis we additionally examined the relationship of [THg] with liver-related enzymes serum aspartate (AST) and alanine aminotransferase (ALT). We observed regional differences in cytokine and chemokine measurements and immune protein associations. There was a positive association between total WBC counts and [THg] in AI pups, whereas a negative association between lymphocytes and [THg] in SEA pups. These findings may indicate regional variation in proliferation and differentiation of hematopoietic cells, differences in immune system development, and/or a difference in antigenic stimuli. No associations between [THg] and cytokines, chemokines, AST or ALT were found. Observed regional differences in cytokine and chemokine milieu during gestational and early development in SSL pups could lead to an imbalance in cell differentiation that could impact immunological resiliency in juvenile and adult life stages. We report concentration ranges of a suite of cytokines and chemokines which may prove to be a useful metric for ecotoxicology and risk assessment studies in SSLs and other wildlife.

Platypus and echidna genomes reveal mammalian biology and evolution

Egg-laying mammals (monotremes) are the only extant mammalian outgroup to therians (marsupial and eutherian animals) and provide key insights into mammalian evolution1,2. Here we generate and analyse reference genomes of the platypus (Ornithorhynchus anatinus) and echidna (Tachyglossus aculeatus), which represent the only two extant monotreme lineages. The nearly complete platypus genome assembly has anchored almost the entire genome onto chromosomes, markedly improving the genome continuity and gene annotation. Together with our echidna sequence, the genomes of the two species allow us to detect the ancestral and lineage-specific genomic changes that shape both monotreme and mammalian evolution. We provide evidence that the monotreme sex chromosome complex originated from an ancestral chromosome ring configuration. The formation of such a unique chromosome complex may have been facilitated by the unusually extensive interactions between the multi-X and multi-Y chromosomes that are shared by the autosomal homologues in humans. Further comparative genomic analyses unravel marked differences between monotremes and therians in haptoglobin genes, lactation genes and chemosensory receptor genes for smell and taste that underlie the ecological adaptation of monotremes.

Sickle Cell Disease: Role of Oxidative Stress and Antioxidant Therapy

Sickle cell disease (SCD) is the most common hereditary disorder of hemoglobin (Hb), which affects approximately a million people worldwide. It is characterized by a single nucleotide substitution in the β-globin gene, leading to the production of abnormal sickle hemoglobin (HbS) with multi-system consequences. HbS polymerization is the primary event in SCD. Repeated polymerization and depolymerization of Hb causes oxidative stress that plays a key role in the pathophysiology of hemolysis, vessel occlusion and the following organ damage in sickle cell patients. For this reason, reactive oxidizing species and the (end)-products of their oxidative reactions have been proposed as markers of both tissue pro-oxidant status and disease severity. Although more studies are needed to clarify their role, antioxidant agents have been shown to be effective in reducing pathological consequences of the disease by preventing oxidative damage in SCD, i.e., by decreasing the oxidant formation or repairing the induced damage. An improved understanding of oxidative stress will lead to targeted antioxidant therapies that should prevent or delay the development of organ complications in this patient population.

Comparative transcriptomics of spotted seatrout (Cynoscion nebulosus) populations to cold and heat stress

Resilience to climate change depends on a species' adaptive potential and phenotypic plasticity. The latter can enhance survival of individual organisms during short periods of extreme environmental perturbations, allowing genetic adaptation to take place over generations. Along the U.S. East Coast, estuarine-dependent spotted seatrout (Cynoscion nebulosus) populations span a steep temperature gradient that provides an ideal opportunity to explore the molecular basis of phenotypic plasticity. Genetically distinct spotted seatrout sampled from a northern and a southern population were exposed to acute cold and heat stress (5 biological replicates in each treatment and control group), and their transcriptomic responses were compared using RNA-sequencing (RNA-seq). The southern population showed a larger transcriptomic response to acute cold stress, whereas the northern population showed a larger transcriptomic response to acute heat stress compared with their respective population controls. Shared transcripts showing significant differences in expression levels were predominantly enriched in pathways that included metabolism, transcriptional regulation, and immune response. In response to heat stress, only the northern population significantly upregulated genes in the apoptosis pathway, which could suggest greater vulnerability to future heat waves in this population as compared to the southern population. Genes showing population-specific patterns of expression, including hpt, acot, hspa5, and hsc71, are candidates for future studies aiming to monitor intraspecific differences in temperature stress responses in spotted seatrout. Our findings contribute to the current understanding of phenotypic plasticity and provide a basis for predicting the response of a eurythermal fish species to future extreme temperatures.

Screening and identification of haptoglobin showing its important role in pathophysiological process of gallbladder carcinoma

Gallbladder cancer (GBC) with poor prognosis has been a major cause of cancer-related deaths worldwide. In this study, we aimed to screen and identify crucial genes in GBC through integrative analysis of multiple datasets and further experimental validation. A candidate crucial gene, up-regulated haptoglobin (HP), was firstly screened, and then further analysis and validation mainly focused on whether higher enrichment level of HP was responsible for pathophysiological process of GBC. HP was found with diverse expression patterns in various cancer types, and the dynamic expression patterns indicated its spatiotemporal characteristics in different tissues and disease stages, implicating its role in multiple biological processes. Further experimental validation showed that HP could promote the GBC-SD cell proliferation, migration and invasion, implying its role in pathophysiological process of GBC. HP may have a crucial role in occurrence and development of GBC, and it provides possibility as a potential biomarker or target in cancer prognosis and treatment.

βCysteine 93 in human hemoglobin: a gateway to oxidative stability in health and disease

βcysteine 93 residue plays a key role in oxygen (O2)-linked conformational changes in the hemoglobin (Hb) molecule. This solvent accessible residue is also a target for binding of thiol reagents that can remotely alter O2 affinity, cooperativity, and Hb's sensitivity to changes in pH. In recent years, βCys93 was assigned a new physiological role in the transport of nitric oxide (NO) through a process of S-nitrosylation as red blood cells (RBCs) travel from lungs to tissues. βCys93 is readily and irreversibly oxidized in the presence of a mild oxidant to cysteic acid, which causes destabilization of Hb resulting in improper protein folding and the loss of heme. Under these oxidative conditions, ferryl heme (HbFe4+), a higher oxidation state of Hb is formed together with its protein radical (.HbFe4+). This radical migrates to βCys93 and interacts with other "hotspot" amino acids that are highly susceptible to oxidative modifications. Oxidized βCys93 may therefore be used as a biomarker of oxidative stress, reflecting the deterioration of Hb within RBCs intended for transfusion or RBCs from patients with hemoglobinopathies. Site specific mutation of a redox active amino acid(s) to reduce the ferryl heme or direct chemical modifications that can shield βCys93 have been proposed to improve oxidative resistance of Hb and may offer a protective therapeutic strategy.

Mechanisms of Toxicity and Modulation of Hemoglobin-based Oxygen Carriers

Several adverse events have been associated with the infusion of hemoglobin-based oxygen carriers (HBOCs), including transient hypertension, gastrointestinal, pancreatic/liver enzyme elevation, and cardiac/renal injury in humans. Although several mechanisms have been suggested, the basis of HBOC toxicity is still poorly understood. Scavenging of vascular endothelial nitric oxide (NO) and heme-mediated oxidative side reactions are thought to be the major causes of toxicity. However, based on more recent preclinical studies, oxidative pathways (driven by the heme prosthetic group) seem to play a more prominent role in the overall toxicity of free Hb or HBOCs. HBOCs display a diversity of physicochemical properties, including molecular size/cross-linking characteristics leading to differences in oxygen affinity, allosteric, redox properties, and even oxidative inactivation by protein/heme clearing mechanisms. These diverse characteristics can therefore be manipulated independently, leaving open the possibility of engineering a safe and effective HBOC. To date, several antioxidative strategies have been proposed to counteract the redox side reactions of current generation HBOCs.

A wealth of genotype-specific proteoforms fine-tunes hemoglobin scavenging by haptoglobin

The serum haptoglobin protein (Hp) scavenges toxic hemoglobin (Hb) leaked into the bloodstream from erythrocytes. In humans, there are two frequently occurring allelic forms of Hp, resulting in three genotypes: Homozygous Hp 1-1 and Hp 2-2, and heterozygous Hp 2-1. The Hp genetic polymorphism has an intriguing effect on the quaternary structure of Hp. The simplest form, Hp 1-1, forms dimers consisting of two α1β units, connected by disulfide bridges. Hp 2-1 forms mixtures of linear (α1)2(α2)n-2(β)n oligomers (n > 1) while Hp 2-2 occurs in cyclic (α2)n(β)n oligomers (n > 2). Different Hp genotypes bind Hb with different affinities, with Hp 2-2 being the weakest binder. This behavior has a significant influence on Hp's antioxidant capacity, with potentially distinctive personalized clinical consequences. Although Hp has been studied extensively in the past, the finest molecular details of the observed differences in interactions between Hp and Hb are not yet fully understood. Here, we determined the full proteoform profiles and proteoform assemblies of all three most common genetic Hp variants. We combined several state-of-the-art analytical methods, including various forms of chromatography, mass photometry, and different tiers of mass spectrometry, to reveal how the tens to hundreds distinct proteoforms and their assemblies influence Hp's capacity for Hb binding. We extend the current knowledge by showing that Hb binding does not just depend on the donor's genotype, but is also affected by variations in Hp oligomerization, glycosylation, and proteolytic processing of the Hp α-chain.

Pro-inflammatory Actions of Heme and Other Hemoglobin-Derived DAMPs

Damage associated molecular patterns (DAMPs) are endogenous molecules originate from damaged cells and tissues with the ability to trigger and/or modify innate immune responses. Upon hemolysis hemoglobin (Hb) is released from red blood cells (RBCs) to the circulation and give a rise to the production of different Hb redox states and heme which can act as DAMPs. Heme is the best characterized Hb-derived DAMP that targets different immune and non-immune cells. Heme is a chemoattractant, activates the complement system, modulates host defense mechanisms through the activation of innate immune receptors and the heme oxygenase-1/ferritin system, and induces innate immune memory. The contribution of oxidized Hb forms is much less studied, but some evidence show that these species might play distinct roles in intravascular hemolysis-associated pathologies independently of heme release. This review aims to summarize our current knowledge about the formation and pro-inflammatory actions of heme and other Hb-derived DAMPs.

Tangential flow filtration of haptoglobin

Haptoglobin (Hp) is a plasma glycoprotein that scavenges cell-free hemoglobin (Hb). Hp has various potential therapeutic applications, but it has been mainly studied for treatment of acute hemolytic conditions that can arise from situations such as massive blood transfusion, infusion of stored red blood cells, severe burns, trauma, sepsis, radiation injury, and others. Therefore, Hp may also be beneficial during chronic hemolytic disease states such as hereditary spherocytosis, nocturnal hemoglobinuria, sickle-cell anemia, and malaria. Various methods have been developed to purify Hp from plasma or plasma fractions. However, none of these methods have exploited the large molecular weight (MW) range distribution of Hp polymers to easily isolate Hp from other plasma proteins. The present study used tangential flow filtration (TFF) to isolate polymeric Hp from plasma proteins using human Fraction IV (FIV) as the starting material. After removal of insoluble material from a suspension of FIV paste, the protein mixture was clarified on a 0.2 μm hollow fiber (HF) TFF filter. The clarified protein solution was then bracketed based on protein MW using HF filters with MW cut-offs (MWCOs) of 750, 500, and 100 kDa. Using untreated FIV, the Hp purity of the main bracket was ~75% with a total Hb binding capacity (HbBC) yield of 1.2 g starting from 500 g of FIV paste. However, pretreatment of FIV with fumed silica to remove lipoproteins increased Hp purity to >95% with a HbBC yield of 1.7 g per 500 g of FIV. Taken together this study provides a novel and scalable method to purify Hp from plasma or plasma fractions.

Formation and Detection of Highly Oxidized Hemoglobin Forms in Biological Fluids during Hemolytic Conditions

Hemolytic diseases are characterized by an accelerated breakdown of red blood cells (RBCs) and the release of hemoglobin (Hb). Following, RBC lysis Hb oxidation occurs with the formation of different redox states of Hb (metHb and ferrylHb) and the release of heme. ferrylHb is unstable and decomposes to metHb with the concomitant formation of globin radicals and eventually covalently crosslinked Hb multimers. The goal of the present study was to determine the concentrations of the different redox states of Hb in biological samples during hemolytic conditions. We used plasma and urine samples of mice with intravascular hemolysis and human cerebrospinal fluid (CSF) samples following intraventricular hemorrhage. Because ferrylHb is highly unstable, we also addressed the fate of this species. metHb and free heme time-dependently accumulate in plasma and CSF samples following intravascular hemolysis and intraventricular hemorrhage, respectively. ferrylHb is hardly detectable in the biological samples during hemolytic conditions. Under in vitro conditions, ferrylHb decomposes quickly to metHb, which process is associated with the formation of covalently crosslinked Hb multimers. We detected these covalently crosslinked Hb multimers in plasma, urine, and CSF samples during hemolytic conditions. Because globin modification is specific for these Hb forms, we propose to call this heterogeneous form of Hb produced during ferrylHb decomposition as globin-modified oxidized Hb (gmoxHb). Understanding the formation and the contribution of gmoxHb species to the pathogenesis of hemolytic conditions could have therapeutic implications in the treatment of hemolytic diseases.

The Iron Biology Status of Peritoneal Dialysis Patients May Be a Risk Factor for Development of Infectious Peritonitis

Background:Infectious peritonitis is a clinically important condition contributing to the significant mortality and morbidity rates observed in peritoneal dialysis (PD) patients. Although some of the socioeconomic risk factors for PD-associated peritonitis have been identified, it is still unclear why certain patients are more susceptible than others to infection.Methods:We examined the molecular components of human peritoneal dialysate (HPD) in an attempt to identify factors that might increase patient susceptibility to infection. Characterization studies were performed on initial and follow-up dialysate samples collected from 9 renal failure patients on PD.Results:Our in vitro data showed that peritonitis-causing bacteria grew differently in the patient dialysates. Proteomic analysis identified an association between transferrin presence and infection risk, as peritoneal transferrin was discovered to be iron-saturated, which was in marked contrast to transferrin in blood. Further, use of radioactive iron-labeled transferrin showed peritoneal transferrin could act as a direct iron source for the growth of peritonitis-causing bacteria. We also found catecholamine stress hormones noradrenaline and adrenaline were present in the dialysates and were apparently involved in enhancing the growth of the bacteria via transferrin iron provision. This suggests the iron biology status of the PD patient may be a risk factor for development of infectious peritonitisConclusions:Collectively, our study suggests transferrin and catecholamines within peritoneal dialysate may be indicators of the potential for bacterial growth in HPD and, as infection risk factors, represent possible future targets for therapeutic manipulation.

Nitroso-Oxidative Stress, Acute Phase Response, and Cytogenetic Damage in Wistar Rats Treated with Adrenaline

This study is aimed at analysing biochemical and genetic endpoints of toxic effects after administration of adrenaline. For this purpose, the study was carried out on Wistar rats and three doses of adrenaline were used: 0.75 mg/kg, 1.5 mg/kg, and 3 mg/kg body weight. To achieve these aims, we investigated the effects of adrenaline on catalase (CAT), Cu, Zn-superoxide dismutase (SOD), malondialdehyde (MDA), nitrite (NO₂−), carbonyl groups (PCC), and nitrotyrosine (3-NT). Total activity of lactate dehydrogenase (LDH), its relative distribution (LDH₁–LDH₅) activity, level of acute phase proteins (APPs), and genotoxic effect were also evaluated. The obtained results revealed that all doses of adrenaline induced a significant rise in CAT activity, MDA level, PCC, NO₂⁻, and 3-NT and a significant decrease in SOD activity compared to control. Adrenaline exerted an increase in total activity of LDH, LDH₁, and LDH₂ isoenzymes. Further study showed that adrenaline significantly decreased serum albumin level and albumin-globulin ratio, while the level of APPs (α₁-acid glycoprotein and haptoglobulin) is increased. The micronucleus test revealed a genotoxic effect of adrenaline at higher concentrations (1.5 mg/kg and 3 mg/kg body weight) compared to untreated rats. It can be concluded that adrenaline exerts oxidative and nitrative stress in rats, increased damage to lipids and proteins, and damage of cardiomyocytes and cytogenetic damage. Obtained results may contribute to better understanding of the toxicity of adrenaline with aims to preventing its harmful effects.

Mountain Cycling Ultramarathon Effects on Inflammatory and Hemoglobin Responses

PURPOSE

This study aimed to analyze the cumulative physiological burden of repetitive, strenuous exercise held during mountain cycling ultramarathon on regulatory mechanisms of hemoglobin degradation.

METHODS

Fifty-five nonprofessional athletes (mean age, 44.8 ± 7.1 yr) participating in a 9-consecutive-day mountain cycling ultramarathon (TransPortugal) underwent anthropometric, hematological, and biochemical assessments before and immediately after the race. Participants were further stratified as completers (nine courses) or noncompleters and were divided according to the time they took to complete the race. The heme oxygenase-1 (HMOX1) functional genetic polymorphism and haptoglobin (HP) phenotypic variants were also analyzed.

RESULTS

Total leukocytes, neutrophil count, and monocyte count increased, whereas decreases in erythrocyte counts and hemoglobin were found between pre- and postultramarathon. Circulating haptoglobin (Hp) was increased, whereas its soluble receptor (sCD163) decreased. Athletes who completed all nine courses presented with increased leukocyte, neutrophil, and erythrocyte counts, as well as hemoglobin, red cell distribution width, total bilirubin, and total cholesterol levels. High-sensitivity C-reactive protein and Hp decreased in comparison with noncompleters. HMOX1 and HP genetic polymorphisms were associated with biochemical profile, notably with Hp levels. Analysis of covariance showed a significant effect of HP phenotype in Hp circulating levels at the end of race and on the magnitude of variation from pre- to postrace.

CONCLUSIONS

Present findings support a comodulatory influence of genetic- and exercise-associated factors on resulting inflammatory and hemoglobin catabolic marker Hp after highly demanding endurance exercise.

Cross-linked hemoglobin bis-tetramers from bioorthogonal coupling do not induce vasoconstriction in the circulation

BACKGROUND

Hemoglobin-based oxygen carriers (HBOCs) are potential alternatives to red blood cells in transfusions. Clinical trials using early versions of HBOCs noted adverse effects that appeared to result from removal of the vasodilator nitric oxide (NO). Previous reports suggest that size-enlarged HBOCs may avoid NO-rich regions along the vasculature and therefore not cause vasoconstriction and hypertension.

STUDY DESIGN AND METHODS

Hemoglobin (Hb) bis-tetramers (bis-tetramers of hemoglobin that are prepared using CuAAC chemistry [BT-Hb] and bis-tetramers of hemoglobin that are specifically acetylated and prepared using CuAAC chemistry [BT-acHb]) can be reliably produced by a bio-orthogonal cyclo-addition approach. We considered that an HBOC derived from chemical coupling of two Hbs would be sufficiently large to avoid NO scavenging and related side effects. The ability of intravenously infused BT-Hb and BT-acHb to remain in the circulation without causing hypertension were determined in wild-type (WT) and diabetic (db/db) mouse models.

RESULTS

In WT mice, the coupled oxygen-carrying proteins retained their function over several hours after administration. No significant changes in systolic blood pressure from baseline were observed after intravenous infusion of BT-Hb or BT-acHb in awake WT and db/db mice. In contrast, infusion of native Hb or cross-linked Hb tetramers in both animal models induced systemic hypertension.

CONCLUSION

The results of this study indicate that bis-tetrameric HBOCs derived from the bio-orthogonal cyclo-addition process are likely to overcome clinical issues that arise from NO scavenging by Hb derivatives.

Haptoglobin levels are influenced by Hp1-Hp2 polymorphism, obesity, inflammation, and hypertension in type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is an inflammatory condition associated to obesity and increased oxidative stress. Haptoglobin (Hp) is an acute phase reactant that scavenges extracorpuscular hemoglobin from circulation and prevents heme-iron oxidative damage.

OBJECTIVE

To assess the association between Hp levels and Hp1-Hp2 gene polymorphism and clinical and laboratory parameters in patients with T2DM.

METHODS

The study sample consisted of 102 T2DM patients and 62 controls. Hp plasma levels were measured using an ELISA assay, and Hp genotyping was performed using a specific two-step allelic polymerase chain reaction.

RESULTS

Hp levels were higher in T2DM patients as compared to controls (p=0.005). T2DM patients with high blood pressure had higher Hp levels than patients without this comorbidity (p=0.021). Obese T2DM patients had higher Hp levels as compared to obese controls (p=0.009) and to non-obese T2DM patients (p=0.003). The Hp1-Hp1 genotype was showed to be associated to T2DM according to additive (OR=3.038, 95% CI 1.127-8.192; p=0.036) and dominant model (OR=0.320, 95% CI 0.118-0.839; p=0.010), but Hp2 allele carriers contributed with higher Hp levels in T2DM as compared to controls. Waist circumference (p=0.002), BMI (p=0.001), and IL-6 (p=0.012), and hs-CRP (p=0.001) levels positively correlated with Hp levels in the T2DM group.

CONCLUSION

These results suggest that Hp levels are influenced by Hp1-Hp2 polymorphism, obesity, inflammatory status, and high blood pressure in T2DM.

N-glycan microheterogeneity regulates interactions of plasma proteins

Glycosylation is one of the most common and complex posttranslation modifications that significantly influences protein structure and function. However, linking individual glycan structures to protein interactions remains challenging and typically requires multiple techniques. Here, we establish a mass-spectrometric approach to systematically dissect the microheterogeneity of two important serum proteins, α1-acid glycoprotein and haptoglobin, and relate glycan features to drug and protein-binding interaction kinetics. We found that the degree of N-glycan branching and extent of terminal fucosylation can attenuate or enhance these interactions, providing important insight into drug transport in plasma. Our study demonstrates an approach capable of investigating how protein glycosylation fine-tunes protein–drug interactions at the glycan-specific level and will prove universally useful for studying glycoprotein interactions.

Altered glycosylation patterns of plasma proteins are associated with autoimmune disorders and pathogenesis of various cancers. Elucidating glycoprotein microheterogeneity and relating subtle changes in the glycan structural repertoire to changes in protein–protein, or protein–small molecule interactions, remains a significant challenge in glycobiology. Here, we apply mass spectrometry-based approaches to elucidate the global and site-specific microheterogeneity of two plasma proteins: α1-acid glycoprotein (AGP) and haptoglobin (Hp). We then determine the dissociation constants of the anticoagulant warfarin to different AGP glycoforms and reveal how subtle N-glycan differences, namely, increased antennae branching and terminal fucosylation, reduce drug-binding affinity. Conversely, similar analysis of the haptoglobin–hemoglobin (Hp–Hb) complex reveals the contrary effects of fucosylation and N-glycan branching on Hp–Hb interactions. Taken together, our results not only elucidate how glycoprotein microheterogeneity regulates protein–drug/protein interactions but also inform the pharmacokinetics of plasma proteins, many of which are drug targets, and whose glycosylation status changes in various disease states.

Inflammation in sickle cell disease

The primary β-globin gene mutation that causes sickle cell disease (SCD) has significant pathophysiological consequences that result in hemolytic events and the induction of the inflammatory processes that ultimately lead to vaso-occlusion. In addition to their role in the initiation of the acute painful vaso-occlusive episodes that are characteristic of SCD, inflammatory processes are also key components of many of the complications of the disease including autosplenectomy, acute chest syndrome, pulmonary hypertension, leg ulcers, nephropathy and stroke. We, herein, discuss the events that trigger inflammation in the disease, as well as the mechanisms, inflammatory molecules and cells that propagate these inflammatory processes. Given the central role that inflammation plays in SCD pathophysiology, many of the therapeutic approaches currently under pre-clinical and clinical development for the treatment of SCD endeavor to counter aspects or specific molecules of these inflammatory processes and it is possible that, in the future, we will see anti-inflammatory drugs being used either together with, or in place of, hydroxyurea in those SCD patients for whom hematopoietic stem cell transplants and evolving gene therapies are not a viable option.

Haptoglobin and hemopexin inhibit vaso-occlusion and inflammation in murine sickle cell disease: Role of heme oxygenase-1 induction

During hemolysis, hemoglobin and heme released from red blood cells promote oxidative stress, inflammation and thrombosis. Plasma haptoglobin and hemopexin scavenge free hemoglobin and heme, respectively, but can be depleted in hemolytic states. Haptoglobin and hemopexin supplementation protect tissues, including the vasculature, liver and kidneys. It is widely assumed that these protective effects are due primarily to hemoglobin and heme clearance from the vasculature. However, this simple assumption does not account for the consequent cytoprotective adaptation seen in cells and organs. To further address the mechanism, we used a hyperhemolytic murine model (Townes-SS) of sickle cell disease to examine cellular responses to haptoglobin and hemopexin supplementation. A single infusion of haptoglobin or hemopexin (± equimolar hemoglobin) in SS-mice increased heme oxygenase-1 (HO-1) in the liver, kidney and skin several fold within 1 hour and decreased nuclear NF-ĸB phospho-p65, and vaso-occlusion for 48 hours after infusion. Plasma hemoglobin and heme levels were not significantly changed 1 hour after infusion of haptoglobin or hemopexin. Haptoglobin and hemopexin also inhibited hypoxia/reoxygenation and lipopolysaccharide-induced vaso-occlusion in SS-mice. Inhibition of HO-1 activity with tin protoporphyrin blocked the protections afforded by haptoglobin and hemopexin in SS-mice. The HO-1 reaction product carbon monoxide, fully restored the protection, in part by inhibiting Weibel-Palade body mobilization of P-selectin and von Willebrand factor to endothelial cell surfaces. Thus, the mechanism by which haptoglobin and hemopexin supplementation in hyperhemolytic SS-mice induces cytoprotective cellular responses is linked to increased HO-1 activity.

Induction of NLRP3 Inflammasome Activation by Heme in Human Endothelial Cells

Hemolytic or hemorrhagic episodes are often associated with inflammation even when infectious agents are absent suggesting that red blood cells (RBCs) release damage-associated molecular patterns (DAMPs). DAMPs activate immune and nonimmune cells through pattern recognition receptors. Heme, released from RBCs, is a DAMP and induces IL-1β production through the activation of the nucleotide-binding domain and leucine-rich repeat-containing family and pyrin domain containing 3 (NLRP3) in macrophages; however, other cellular targets of heme-mediated inflammasome activation were not investigated. Because of their location, endothelial cells can be largely exposed to RBC-derived DAMPs; therefore, we investigated whether heme and other hemoglobin- (Hb-) derived species induce NLRP3 inflammasome activation in these cells. We found that heme upregulated NLRP3 expression and induced active IL-1β production in human umbilical vein endothelial cells (HUVECs). LPS priming largely amplified the heme-mediated production of IL-1β. Heme administration into C57BL/6 mice induced caspase-1 activation and cleavage of IL-1β which was not observed in NLRP3^-/- mice. Unfettered production of reactive oxygen species played a critical role in heme-mediated NLRP3 activation. Activation of NLRP3 by heme required structural integrity of the heme molecule, as neither protoporphyrin IX nor iron-induced IL-1β production. Neither naive nor oxidized forms of Hb were able to induce IL-1β production in HUVECs. Our results identified endothelial cells as a target of heme-mediated NLRP3 activation that can contribute to the inflammation triggered by sterile hemolysis. Thus, understanding the characteristics and cellular counterparts of RBC-derived DAMPs might allow us to identify new therapeutic targets for hemolytic diseases.

Mendelian randomization analysis to assess a causal effect of haptoglobin on macroangiopathy in Chinese type 2 diabetes patients

Background

Haptoglobin (Hp) functions as an antioxidant by binding with haemoglobin. We investigated whether serum Hp has a causal effect on macroangiopathy via Mendelian randomization (MR) analysis with common variants of the Hp gene in Chinese patients with type 2 diabetes.

Methods

A total of 5687 type 2 diabetes patients were recruited and genotyped for the Hp gene. Clinical features and vascular imaging tests were applied to diagnose macroangiopathy. The association between common Hp genotypes and macroangiopathy was analyzed in the whole population. Serum Hp levels were measured by enzyme-linked immunosorbent assay in a subset of 935 patients. We individually analyzed the correlations among Hp levels, Hp genotypes and macroangiopathy. Further, 8-hydroxy-2′-deoxyguanosine (8-OHdG), an oxidative marker of DNA damage, was examined to evaluate the levels of oxidative stress.

Results

Common Hp genotypes were correlated with macroangiopathy (OR = 1.140 [95% CI 1.005–1.293], P = 0.0410 for the Hp 1 allele). Serum Hp levels were associated with both common Hp genotypes (P = 3.55 × 10⁻³¹) and macroangiopathy (OR = 2.123 [95% CI 1.098–4.102], P = 0.0252) in the subset of 935 patients. In the MR analysis, the directional trends of the observed and predicted relationships between common Hp genotypes and macroangiopathy were the same (OR 1.357 and 1.130, respectively). Furthermore, common Hp genotypes and Hp levels were associated with serum 8-OHdG levels (P = 0.0001 and 0.0084, respectively).

Conclusions

Our study provides evidence for a causal relationship between serum Hp levels and macroangiopathy in Chinese type 2 diabetes patients by MR analysis.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0662-7) contains supplementary material, which is available to authorized users.

Pro-Inflammatory Actions of Red Blood Cell-Derived DAMPs

Damage-associated molecular patterns (DAMPs) or alarmins are endogenous danger signals that are derived from damaged cells and extracellular matrix degradation, capable of triggering innate immune response to promote tissue damage repair. Hemolytic or hemorrhagic episodes are often associated with inflammation, even when infectious agents are absent, suggesting that damaged red blood cells (RBCs) release DAMPs.Hemoglobin (Hb) composes 96% of the dry weight of RBCs; therefore upon hemolysis, tremendous amounts of Hb are released into the extracellular milieu. Hb oxidation occurs outside the protective environment of RBCs, leading to the formation of different Hb oxidation products and heme. Heme acts as a prototypic DAMP participating in toll-like receptor as well as intracellular nucleotide-binding oligomerization domain-like receptor signaling. Oxidized Hb forms also possess some inflammatory actions independently of their heme releasing capability. Non-Hb-derived DAMPs such as ATP, interleukin-33, heat shock protein 70, as well as RBC membrane-derived microparticles might also contribute to the innate immune response triggered by hemolysis/hemorrhage.In this chapter we will discuss the inflammatory properties of RBC-derived DAMPs with a particular focus on Hb derivatives, as well as therapeutic potential of the endogenous Hb and heme-binding proteins haptoglobin and hemopexin in the prevention of hemolysis/hemorrhage-associated inflammation.

Haptoglobin Phenotypes and Susceptibility to Schistosoma Parasites Infection in Central Sudan

Haptoglobin (Hp) is an acute phase protein that binds the free hemoglobin (Hb), thus preventing iron loss and renal damage. Hp also has antioxidative and immunomodulatory properties. Three Hp phenotypes have been identified in human: Hp1-1, Hp2-1, and Hp2-2. Hp polymorphisms have been related to susceptibility of various diseases. In this study, we aimed to assess the possible association of Hp phenotypes polymorphism to Schistosoma parasites infection in central Sudan. We have investigated the Hp phenotypes polymorphism distribution in the serum of 125 (93 S. mansoni, 13 S. haematobium and 19 infected with both "co-infection") parasitologically confirmed infected individuals and 208 healthy individuals served as control. Hp phenotypes have been determined by polyacrylamide gel electrophoresis followed by benzidine staining. Our study revealed that Hp1-1 percentage frequency was significantly higher in infected individuals than healthy control individuals 51% and 26% respectively. Our data suggest that Hp1-1 phenotype may upsurge the susceptibility to Schistosoma parasites infection in central Sudan.

Oxidative pathways in the sickle cell and beyond

Polymerization of deoxy sickle cell hemoglobin (HbS) is well recognized as the primary event that triggers the classic cycles of sickling/unsickling of patients red blood cells (RBCs). RBCs are also subjected to continuous endogenous and exogenous oxidative onslaughts resulting in hemolytic rate increases which contribute to the evolution of vasculopathies associated with this disease. Compared to steady-state conditions, the occurrences of vaso-occlusive crises increase the levels of both RBC-derived microparticles as well as extracellular Hb in circulation. Common byproduct resulting from free Hb oxidation and from Hb-laden microparticles is heme (now recognized as damage associated molecular pattern (DAMP) molecule) which has been shown to initiate inflammatory responses. This review provides new insights into the interplay between microparticles, free Hb and heme focusing on Hb's pseudoperoxidative activity that drives RBC's cytosolic, membrane changes as well as oxidative toxicity towards the vascular system. Emerging antioxidative strategies that include the use of protein and heme scavengers in controlling Hb oxidative pathways are discussed.

A facile way to prepare functionalized dextran nanogels for conjugation of hemoglobin

Nanogels with several special advantages have been widely applied in protein delivery. However, biocompatible and biodegradable nanogels used for hemoglobin (Hb) delivery are far less explored. Herein, we developed a facile method to prepare functionalized dextran nanogels for conjugation of Hb. In situ cross-linked and aldehyde group functionalized nanogels (FNGs) were prepared from dextran-g-succinic anhydride-g-dopamine conjugate (Dex-SA-DA) assembly by simple pH adjustion and oxidization in water. Hb was further conjugated into the swelling FNGs by Schiff base reaction under mild condition. The obtained hemoglobin-loaded nanogels (HbNGs) exhibited high stability, oxygen affinity and good hemo-compatibility, suggesting the potential for oxygen carriers. We expected that the designed functionalized nanogels with high stability and loading capacity could bring a new opportunity for protein delivery.

Hemoglobin inhibits albumin uptake by proximal tubule cells: implications for sickle cell disease

Proximal tubule (PT) dysfunction, including tubular proteinuria, is a significant complication in young sickle cell disease (SCD) that can eventually lead to chronic kidney disease. Hemoglobin (Hb) dimers released from red blood cells upon hemolysis are filtered into the kidney and internalized by megalin/cubilin receptors into PT cells. The PT is especially sensitive to heme toxicity, and tubular dysfunction in SCD is thought to result from prolonged exposure to filtered Hb. Here we show that concentrations of Hb predicted to enter the tubule lumen during hemolytic crisis competitively inhibit the uptake of another megalin/cubilin ligand (albumin) by PT cells. These effects were independent of heme reduction state. The Glu7Val mutant of Hb that causes SCD was equally effective at inhibiting albumin uptake compared with wild-type Hb. Addition of the Hb scavenger haptoglobin (Hpt) restored albumin uptake in the presence of Hb, suggesting that Hpt binding to the Hb αβ dimer-dimer interface interferes with Hb binding to megalin/cubilin. BLAST searches and structural modeling analyses revealed regions of similarity between Hb and albumin that map to this region and may represent sites of Hb interaction with megalin/cubilin. Our studies suggest that impaired endocytosis of megalin/cubilin ligands, rather than heme toxicity, may be the cause of tubular proteinuria in SCD patients. Additionally, loss of these filtered proteins into the urine may contribute to the extra-renal pathogenesis of SCD.

Hemoglobin-Based Blood Substitutes and the Treatment of Sickle Cell Disease: More Harm than Help?

Intense efforts have been made by both industry and academia over the last three decades to produce viable hemoglobin (Hb)-based oxygen carriers (HBOCs), also known as “blood substitutes”. Human trials conducted so far by several manufactures in a variety of clinical indications, including trauma, and elective surgeries have failed and no product has gained the Food and Drug Administration approval for human use. Safety concerns due to frequent incidences of hemodynamic, cardiac events, and even death led to the termination of some of these trials. Several second generation HBOC products that have been chemically and/or genetically modified (or in some cases ligated with carbon monoxide (CO)) found a new clinical application in conditions as complex as sickle cell disease (SCD). By virtue of higher oxygen affinity (P₅₀) (R-state), and smaller size, HBOCs may be able to reach the microvasculature unload of oxygen to reverse the cycles of sickling/unsickling of the deoxy-sickle cell Hb (HbS) (T-state), thus preventing vaso-occlusion, a central event in SCD pathophysiology. However, biochemically, it is thought that outside the red blood cell (due to frequent hemolysis), free HbS or infused HBOCs are capable of interfering with a number of oxidative and signaling pathways and may, thus, negate any benefit that HBOCs may provide. This review discusses the advantages and disadvantages of using HBOCs in SCD.

Brain iron overload following intracranial haemorrhage

Intracranial haemorrhages, including intracerebral haemorrhage (ICH), intraventricular haemorrhage (IVH) and subarachnoid haemorrhage (SAH), are leading causes of morbidity and mortality worldwide. In addition, haemorrhage contributes to tissue damage in traumatic brain injury (TBI). To date, efforts to treat the long-term consequences of cerebral haemorrhage have been unsatisfactory. Incident rates and mortality have not showed significant improvement in recent years. In terms of secondary damage following haemorrhage, it is becoming increasingly apparent that blood components are of integral importance, with haemoglobin-derived iron playing a major role. However, the damage caused by iron is complex and varied, and therefore, increased investigation into the mechanisms by which iron causes brain injury is required. As ICH, IVH, SAH and TBI are related, this review will discuss the role of iron in each, so that similarities in injury pathologies can be more easily identified. It summarises important components of normal brain iron homeostasis and analyses the existing evidence on iron-related brain injury mechanisms. It further discusses treatment options of particular promise.

Evaluation of Gallium as a Tracer of Exogenous Hemoglobin-Haptoglobin Complexes for Targeted Drug Delivery Applications

Haptoglobin (Hp) is a plasma glycoprotein that generates significant interest in the drug delivery community because of its potential for delivery of antiretroviral medicines with high selectivity to macrophages and monocytes, the latent reservoirs of human immunodeficiency virus. As is the case with other therapies that exploit transport networks for targeted drug delivery, the success of the design and optimization of Hp-based therapies will critically depend on the ability to accurately localize and quantitate Hp-drug conjugates on the varying and unpredictable background of endogenous proteins having identical structure. In this work, we introduce a new strategy for detecting and quantitating exogenous Hp and Hp-based drugs with high sensitivity in complex biological samples using gallium as a tracer of this protein and inductively coupled plasma mass spectrometry (ICP MS) as a method of detection. Metal label is introduced by reconstituting hemoglobin (Hb) with gallium(III)-protoporphyrin IX followed by its complexation with Hp. Formation of the Hp/Hb assembly and its stability are evaluated with native electrospray ionization mass spectrometry. Both stable isotopes of Ga give rise to an abundant signal in ICP MS of a human plasma sample spiked with the metal-labeled Hp/Hb complex. The metal label signal exceeds the spectral interferences' contributions by more than an order of magnitude even with the concentration of the exogenous protein below 10 nM, the level that is more than adequate for the planned pharmacokinetic studies of Hp-based therapeutics. Graphical Abstract ᅟ.

Inhibition of pseudoperoxiadse activity of human red blood cell hemoglobin by methocarbamol

After red blood cells lysis, hemoglobin is released to blood circulation. Hemoglobin is carried in blood by binding to haptoglobin. In normal individuals, no free hemoglobin is observed in the blood, because most of the hemoglobin is in the form of haptoglobin complex. In some diseases that are accompanied by hemolysis, the amount of released hemoglobin is higher than its complementary haptoglobin. As a result, free hemoglobin appears in the blood, which is a toxic compound for these patients and may cause renal failure, hypertensive response and risk of atherogenesis. Free hemoglobin has been determined to have peroxidase activity and considered a pseudoenzyme. In this study, the effect of methocarbamol on the peroxidase activity of human hemoglobin was investigated. Our results showed that the drug inhibited the pseudoenzyme by un-competitive inhibition. Both K_m and V_max decreased by increasing the drug concentration. K_i and IC₅₀ values were determined as 6 and 10mM, respectively. Docking results demonstrated that methocarbamol did not attach to heme group directly. A hydrogen bond linked NH₂ of carbamate group of methocarbamol to the carboxyl group of Asp126 side chain. Two other hydrogen bonds could be also observed between hydroxyl group of the drug and Ser102 and Ser133 residues of the pseudoenzyme.

Fetal hemoglobin, α1-microglobulin and hemopexin are potential predictive first trimester biomarkers for preeclampsia

OBJECTIVE

Overproduction of cell-free fetal hemoglobin (HbF) in the preeclamptic placenta has been recently implicated as a new etiological factor of preeclampsia. In this study, maternal serum levels of HbF and the endogenous hemoglobin/heme scavenging systems were evaluated as predictive biomarkers for preeclampsia in combination with uterine artery Doppler ultrasound.

STUDY DESIGN

Case-control study including 433 women in early pregnancy (mean 13.7weeks of gestation) of which 86 subsequently developed preeclampsia. The serum concentrations of HbF, total cell-free hemoglobin, hemopexin, haptoglobin and α1-microglobulin were measured in maternal serum. All patients were examined with uterine artery Doppler ultrasound. Logistic regression models were developed, which included the biomarkers, ultrasound indices, and maternal risk factors.

RESULTS

There were significantly higher serum concentrations of HbF and α1-microglobulin and significantly lower serum concentrations of hemopexin in patients who later developed preeclampsia. The uterine artery Doppler ultrasound results showed significantly higher pulsatility index values in the preeclampsia group. The optimal prediction model was obtained by combining HbF, α1-microglobulin and hemopexin in combination with the maternal characteristics parity, diabetes and pre-pregnancy hypertension. The optimal sensitivity for all preeclampsia was 60% at 95% specificity.

CONCLUSIONS

Overproduction of placentally derived HbF and depletion of hemoglobin/heme scavenging mechanisms are involved in the pathogenesis of preeclampsia. The combination of HbF and α1-microglobulin and/or hemopexin may serve as a prediction model for preeclampsia in combination with maternal risk factors and/or uterine artery Doppler ultrasound.

Identification of proteins that are differentially expressed in brains with Alzheimer's disease using iTRAQ labeling and tandem mass spectrometry

Alzheimer's disease is one of the leading causes of dementia in the elderly. It is considered the result of complex events involving both genetic and environmental factors. To gain further insights into this complexity, we quantitatively analyzed the proteome of cortex region of brains from patients diagnosed with Alzheimer's disease, using a bottom-up proteomics approach. We identified 721 isobaric-tagged polypeptides. From this universe, 61 were found overexpressed and 69 subexpressed in three brains with Alzheimer's disease in comparison to a normal brain. We determined that the most affected processes involving the overexpressed polypeptides corresponded to ROS and stress responses. For the subexpressed polypeptides, the main processes affected were oxidative phosphorylation, organellar acidification and cytoskeleton. We used Drosophila to validate some of the hits, particularly those non-previously described as connected with the disease, such as Sideroflexin and Phosphoglucomutase-1. We manipulated their homolog genes in Drosophila models of Aβ- and Tau-induced pathology. We found proteins that can either modify Aβ toxicity, Tau toxicity or both, suggesting specific interactions with different pathways. This approach illustrates the potential of Drosophila to validate hits after MS studies and suggest that model organisms should be included in the pipeline to identify relevant targets for Alzheimer's disease.

BIOLOGICAL SIGNIFICANCE

We report a set of differentially expressed proteins in three Alzheimer's disease brains in comparison to a normal brain. Our analyses allowed us to identify that the main affected pathways were ROS and stress responses, oxidative phosphorylation, organellar acidification and cytoskeleton. We validated some identified proteins using genetic models of Amyloid-β and Tau-induced pathology in Drosophila melanogaster. With this approach, Sideroflexin and Phosphoglucomutase-1 were identified as novel proteins connected with Alzheimer's disease.

A novel exonuclease (TaqMan) assay for rapid haptoglobin genotyping

BACKGROUND

Haptoglobin is an acute-phase binding protein that scavenges free hemoglobin. The human haptoglobin gene (HP) is polymorphic with two main alleles, haptoglobin allele 1 (Hp1) and haptoglobin allele 2 (Hp2). The smaller Hp1 allele features no duplication and consists of four exons, whereas the larger Hp2 allele, containing a 1.7 kb duplication, consists of six exons, with the fifth and sixth being highly homologous to exons 3 and 4 of Hp1.

METHODS

We designed an exonuclease (TaqMan) assay targeting single nucleotide differences between the homologous regions of Hp1 and Hp2. The assay contained one probe specifically binding to a site in intron 4 of Hp2, and another probe binding equally to intron 4 of Hp1 and intron 6 of Hp2.

RESULTS

Measurement of post-PCR fluorescence allowed unambiguous discrimination of HP genotypes. Comparison with genotypes obtained by a method based upon allele-specific primers yielded fully corresponding results.

CONCLUSIONS

The new HP genotyping method is fast, reliable, does not require real-time instruments and may be especially useful for high-throughput genotyping.

The Human Endogenous Protection System against Cell-Free Hemoglobin and Heme Is Overwhelmed in Preeclampsia and Provides Potential Biomarkers and Clinical Indicators

Preeclampsia (PE) complicates 3-8% of all pregnancies and manifests clinically as hypertension and proteinuria in the second half of gestation. The pathogenesis of PE is not fully understood but recent studies have described the involvement of cell-free fetal hemoglobin (HbF). Hypothesizing that PE is associated with prolonged hemolysis we have studied the response of the cell-free Hb- and heme defense network. Thus, we have investigated the levels of cell-free HbF (both free, denoted HbF, and in complex with Hp, denoted Hp-HbF) as well as the major human endogenous Hb- and heme-scavenging systems: haptoglobin (Hp), hemopexin (Hpx), α1-microglobulin (A1M) and CD163 in plasma of PE women (n = 98) and women with normal pregnancies (n = 47) at term. A significant increase of the mean plasma HbF concentration was observed in women with PE. Plasma levels of Hp and Hpx were statistically significantly reduced, whereas the level of the extravascular heme- and radical scavenger A1M was significantly increased in plasma of women with PE. The Hpx levels significantly correlated with maternal blood pressure. Furthermore, HbF and the related scavenger proteins displayed a potential to be used as clinical biomarkers for more precise diagnosis of PE and are candidates as predictors of identifying pregnancies with increased risk of obstetrical complications. The results support that PE pathophysiology is associated with increased HbF-concentrations and an activation of the physiological Hb-heme defense systems.

Molecular characterization of two immunity-related acute-phase proteins: Haptoglobin and serum amyloid A from black rockfish (Sebastes schlegeli)

Haptoglobin (Hp) and serum amyloid A (SAA) are two vital proteins involved in inflammatory reactions and are classified as acute-phase proteins. They are released from hepatocytes under inflammatory conditions to protect healthy cells from being damaged by pathogens or from self-destructive mechanisms. In this study, a previously constructed black rockfish (Sebastes schlegeli) cDNA library was used to identify the full-length cDNA sequences of Hp and SAA homologs (RfHp and RfSAA, respectively) and characterize them at the molecular level. As expected, in silico analysis of these homologs showed the typical domain architectures of their known counterparts. Open reading frames of RfHp and RfSAA consisted of 942-bp and 313-bp DNA sequences, respectively. The derived polypeptide sequence of RfHp was composed of 313 amino acids (aa) with a predicted molecular weight of 34 kD, whereas RfSAA had a 121-amino acid sequence with a molecular weight of 13 kD. Phylogenetic analysis as well as pairwise sequence alignment results showed that RfHp was more closely related to Oreochromis mossambicus from an evolutionary perspective while RfSAA was closely related to the Epinephelus coioides ortholog. Although both genes were expressed ubiquitously in the tissues analyzed, they were particularly expressed in liver tissue, suggesting their origin in hepatocytes. Quantitative real-time PCR analysis indicated that both RfHp and RfSAA were significantly up-regulated by both bacterial and viral stimulation in liver tissue, affirming their putative importance in the acute phase of first-line host immune defenses.

Toward Omics-Based, Systems Biomedicine, and Path and Drug Discovery Methodologies for Depression-Inflammation Research

Meta-analyses confirm that depression is accompanied by signs of inflammation including increased levels of acute phase proteins, e.g., C-reactive protein, and pro-inflammatory cytokines, e.g., interleukin-6. Supporting the translational significance of this, a meta-analysis showed that anti-inflammatory drugs may have antidepressant effects. Here, we argue that inflammation and depression research needs to get onto a new track. Firstly, the choice of inflammatory biomarkers in depression research was often too selective and did not consider the broader pathways. Secondly, although mild inflammatory responses are present in depression, other immune-related pathways cannot be disregarded as new drug targets, e.g., activation of cell-mediated immunity, oxidative and nitrosative stress (O&NS) pathways, autoimmune responses, bacterial translocation, and activation of the toll-like receptor and neuroprogressive pathways. Thirdly, anti-inflammatory treatments are sometimes used without full understanding of their effects on the broader pathways underpinning depression. Since many of the activated immune-inflammatory pathways in depression actually confer protection against an overzealous inflammatory response, targeting these pathways may result in unpredictable and unwanted results. Furthermore, this paper discusses the required improvements in research strategy, i.e., path and drug discovery processes, omics-based techniques, and systems biomedicine methodologies. Firstly, novel methods should be employed to examine the intracellular networks that control and modulate the immune, O&NS and neuroprogressive pathways using omics-based assays, including genomics, transcriptomics, proteomics, metabolomics, epigenomics, immunoproteomics and metagenomics. Secondly, systems biomedicine analyses are essential to unravel the complex interactions between these cellular networks, pathways, and the multifactorial trigger factors and to delineate new drug targets in the cellular networks or pathways. Drug discovery processes should delineate new drugs targeting the intracellular networks and immune-related pathways.

Extracellular hemoglobin: the case of a friend turned foe

Hemoglobin (Hb) is a highly conserved molecule present in all life forms and functionally tied to the complexity of aerobic organisms on earth in utilizing oxygen from the atmosphere and delivering to cells and tissues. This primary function sustains the energy requirements of cells and maintains cellular homeostasis. Decades of intensive research has presented a paradigm shift that shows how the molecule also functions to facilitate smooth oxygen delivery through the cardiovascular system for cellular bioenergetic homeostasis and signaling for cell function and defense. These roles are particularly highlighted in the binding of Hb to gaseous molecules carbon dioxide (CO₂), nitric oxide (NO) and carbon monoxide (CO), while also serving indirectly or directly as sources of these signaling molecules. The functional activities impacted by Hb outside of bioenergetics homeostasis, include fertilization, signaling functions, modulation of inflammatory responses for defense and cell viability. These activities are efficiently executed while Hb is sequestered safely within the confines of the red blood cell (rbc). Outside of rbc confines, Hb disaggregates and becomes a danger molecule to cell survival. In these perpectives, Hb function is broadly dichotomous, either a friend in its natural environment providing and facilitating the means for cell function or foe when dislocated from its habitat under stress or pathological condition disrupting cell function. The review presents insights into how this dichotomy in function manifests.

An expandable donor-free supply of functional hepatocytes for toxicology

The B-13 cell is a readily expandable rat pancreatic acinar-like cell that differentiates on simple plastic culture substrata into replicatively-senescent hepatocyte-like (B-13/H) cells in response to glucocorticoid exposure. B-13/H cells express a variety of liver-enriched and liver-specific genes, many at levels similar to hepatocytes in vivo. Furthermore, the B-13/H phenotype is maintained for at least several weeks in vitro, in contrast to normal hepatocytes which rapidly de-differentiate under the same simple – or even under more complex – culture conditions. The origin of the B-13 cell line and the current state of knowledge regarding differentiation to B-13/H cells are presented, followed by a review of recent advances in the use of B-13/H cells in a variety of toxicity endpoints. B-13 cells therefore offer Toxicologists a cost-effective and easy to use system to study a range of toxicologically-related questions. Dissecting the mechanism(s) regulating the formation of B-13/H cell may also increase the likelihood of engineering a human equivalent, providing Toxicologists with an expandable donor-free supply of functional rat and human hepatocytes, invaluable additions to the tool kit of in vitro toxicity tests.