Hypohaptoglobinemia associated with familial epilepsy

Unlocking the link between haptoglobin polymorphism and noninfectious human diseases: insights and implications

Haptoglobin (Hp) is a polymorphic protein that was initially described as a hemoglobin (Hb)-binding protein. The major functions of Hp are to scavenge Hb, prevent iron loss, and prevent heme-based oxidation. Hp regulates angiogenesis, nitric oxide homeostasis, immune responses, and prostaglandin synthesis. Genetic polymorphisms in the Hp gene give rise to different phenotypes, including Hp 1-1, Hp 2-1, and Hp 2-2. Extensive research has been conducted to investigate the association between Hp polymorphisms and several medical conditions including cardiovascular disease, inflammatory bowel disease, cancer, transplantation, and hemoglobinopathies. Generally, the Hp 2-2 phenotype is associated with increased disease risk and poor outcomes. Over the years, the Hp 2 allele has spread under genetic pressures. Individuals with the Hp 2-2 phenotype generally exhibit lower levels of CD163 expression in macrophages. The decreased expression of CD163 may be associated with the poor antioxidant capacity in the serum of subjects carrying the Hp 2-2 phenotype. However, the Hp 1-1 phenotype may confer protection in some cases. The Hp1 allele has strong antioxidant, anti-inflammatory, and immunomodulatory properties. It is important to note that the benefits of the Hp1 allele may vary depending on genetic and environmental factors as well as the specific disease or condition under consideration. Therefore, the Hp1 allele may not necessarily confer advantages in all situations, and its effects may be context-dependent. This review highlights the current understanding of the role of Hp polymorphisms in cardiovascular disease, inflammatory bowel disease, cancer, transplantation, hemoglobinopathies, and polyuria.

Quantitative serum proteome analysis using tandem mass tags in dogs with epilepsy

This study included four groups of dogs (group A: healthy controls, group B: idiopathic epilepsy receiving antiepileptic medication (AEM), group C: idiopathic epilepsy without AEM, group D: structural epilepsy). Comparative quantitative proteomic analysis of serum samples among the groups was the main target of the study. Samples were analyzed by a quantitative Tandem-Mass-Tags approach on the Q-Exactive-Plus Hybrid Quadrupole-Orbitrap mass-spectrometer. Identification and relative quantification were performed in Proteome Discoverer. Data were analyzed using R. Gene ontology terms were analyzed based on Canis lupus familiaris database. Data are available via ProteomeXchange with identifier PXD041129. Eighty-one proteins with different relative adundance were identified in the four groups and 25 were master proteins (p < 0.05). Clusterin (CLU), and apolipoprotein A1 (APOA1) had higher abundance in the three groups of dogs (groups B, C, D) compared to controls. Amine oxidase (AOC3) was higher in abundance in group B compared to groups C and D, and lower in group A. Adiponectin (ADIPOQ) had higher abundance in groups C compared to group A. ADIPOQ and fibronectin (FN1) had higher abundance in group B compared to group C and D. Peroxidase activity assay was used to quantify HP abundance change, validating and correlating with proteomic analysis (r = 0.8796). SIGNIFICANCE: The proteomic analysis of serum samples from epileptic dogs indicated potential markers of epilepsy (CLU), proteins that may contribute to nerve tissue regeneration (APOA1), and contributing factors to epileptogenesis (AOC3). AEM could alter extracellular matrix proteins (FN1). Illness (epilepsy) severity could influence ADIPOQ abundance.

Quantitative proteomics of cerebrospinal fluid using tandem mass tags in dogs with recurrent epileptic seizures

This prospective study included four dog groups (group A: healthy dogs, groups B: dogs with idiopathic epilepsy under antiepileptic medication (AEM), C: idiopathic epilepsy dogs without AEM administration, D: dogs with structural epilepsy). The purpose of the study was to compare the proteomic profile among the four groups. Samples were analyzed by a quantitative Tandem Mass Tags approach using a Q-Exactive-Plus mass-spectrometer. Identification and relative quantification were performed using Proteome Discoverer, and data were analyzed using R. Gene ontology terms were analyzed based on Canis lupus familiaris database. Data are available via ProteomeXchange with identifier PXD018893. Eighteen proteins were statistically significant among the four groups (P < 0.05). MMP2 and EFEMP2 appeared down-regulated whereas HP and APO-A1 were up-regulated (groups B, D). CLEC3B and PEBP4 were up-regulated whereas APO-A1 was down-regulated (group C). IGLL1 was down-regulated (groups B, C) and up-regulated (group D). EFEMP2 was the only protein detected among the four groups and PEBP4 was significantly different among the epileptic dogs. Western blot and SPARCL immunoassay were used to quantify HP abundance change, validating proteomic analysis. Both, showed good correlation with HP levels identified through proteomic analysis (r = 0.712 and r = 0.703, respectively). SIGNIFICANCE: The proteomic analysis from CSF of dogs with epileptic seizures could reflect that MMP2, HP and APO-A1 may contribute to a blood-brain barrier disruption through the seizure-induced inflammatory process in the brain. MMP2 change may indicate the activation of protective mechanisms within the brain tissue. Antiepileptic medication could influence several cellular responses and alter the CSF proteome composition.

Blood-Related Toxicity after Traumatic Brain Injury: Potential Targets for Neuroprotection

Emergency visits, hospitalizations, and deaths due to traumatic brain injury (TBI) have increased significantly over the past few decades. While the primary early brain trauma is highly deleterious to the brain, the secondary injury post-TBI is postulated to significantly impact mortality. The presence of blood, particularly hemoglobin, and its breakdown products and key binding proteins and receptors modulating their clearance may contribute significantly to toxicity. Heme, hemin, and iron, for example, cause membrane lipid peroxidation, generate reactive oxygen species, and sensitize cells to noxious stimuli resulting in edema, cell death, and increased morbidity and mortality. A wide range of other mechanisms such as the immune system play pivotal roles in mediating secondary injury. Effective scavenging of all of these pro-oxidant and pro-inflammatory metabolites as well as controlling maladaptive immune responses is essential for limiting toxicity and secondary injury. Hemoglobin metabolism is mediated by key molecules such as haptoglobin, heme oxygenase, hemopexin, and ferritin. Genetic variability and dysfunction affecting these pathways (e.g., haptoglobin and heme oxygenase expression) have been implicated in the difference in susceptibility of individual patients to toxicity and may be target pathways for potential therapeutic interventions in TBI. Ongoing collaborative efforts are required to decipher the complexities of blood-related toxicity in TBI with an overarching goal of providing effective treatment options to all patients with TBI.

Differential proteome analysis of rat plasma after diisopropyl fluorophosphate (DFP) intoxication, a surrogate of nerve agent sarin

Diisopropyl fluorophosphate (DFP), a surrogate of nerve agent sarin, is an organophosphorus (OP) compound which inhibits neuronal enzyme acetylcholinesterase (AChE). Exposure of this compound leads to a wide range of toxic symptoms and survivors may exhibit long term neurotoxicity related to cognitive and memory defects. Due to ease of availability and similar mechanism of action to other highly toxic nerve agent, DFP is widely used as model compound to trace changes associated with nerve agent exposures. Proximal fluids are widely used for the elucidation of biomarkers for exposure to toxic substances and to study the mechanism of toxicity. Using a rat model of OP intoxication, the present study was carried out to elucidate proteomic changes in plasma associated with DFP intoxication. Rats were exposed to a single dose (0.5 LD₅₀) of DFP and their plasma proteome was studied, one day post exposure by two dimensional gel electrophoresis - mass spectrometry (2DE-MS). Some of the milestone changes were validated by Western blot analysis. A total 15 proteins showed significant fold changes in expression with respect to control after 1 day of DFP intoxication. Most of the proteins showing changes in expression at initial stages were related to immunogenic function, acute phase response, blood coagulation, and stress response. Experiments reported here demonstrate that 0.5 LD₅₀ DFP intoxication leads to AChE inhibition, modulation of immunogenic function, and generation of stress at an early stage. Although, some proteins and their putative functional ramifications indicated similarity with those observed in our previous plasma proteome study, neurodegenerative changes were not observed in plasma of 0.5 LD₅₀ DFP treated animals.

Unique Contribution of Haptoglobin and Haptoglobin Genotype in Aneurysmal Subarachnoid Hemorrhage

Survivors of cerebral aneurysm rupture are at risk for significant morbidity and neurological deficits. Much of this is related to the effects of blood in the subarachnoid space which induces an inflammatory cascade with numerous downstream consequences. Recent clinical trials have not been able to reduce the toxic effects of free hemoglobin or improve clinical outcome. One reason for this may be the inability to identify patients at high risk for neurologic decline. Recently, haptoglobin genotype has been identified as a pertinent factor in diabetes, sickle cell, and cardiovascular disease, with the Hp 2-2 genotype contributing to increased complications. Haptoglobin is a protein synthesized by the liver that binds free hemoglobin following red blood cell lysis, and in doing so, prevents hemoglobin induced toxicity and facilitates clearance. Clinical studies in patients with subarachnoid hemorrhage indicate that Hp 2-2 patients may be a high-risk group for hemorrhage related complications and poor outcome. We review the relevance of haptoglobin in subarachnoid hemorrhage and discuss the effects of genotype and expression levels on the known mechanisms of early brain injury (EBI) and cerebral ischemia after aneurysm rupture. A better understanding of haptoglobin and its role in preventing hemoglobin related toxicity should lead to novel therapeutic avenues.

Histopathologic Changes of Human Vestibular Epithelia in Intralabyrinthine Hemorrhage

Objective:

To determine whether intralabyrinthine hemorrhage affects vestibular hair cells, dark cells, and transitional cells in human temporal bones.

Methods:

We examined 9 temporal bone specimens from 9 deceased donors with unilateral intralabyrinthine hemorrhage (the hemorrhage group) along with their 9 contralateral temporal bone specimens without hemorrhage (the control group). We estimated the density of type I and type II hair cells in all peripheral sensorial organs (including the cristae of the superior, lateral, and posterior semicircular canals, as well as the maculae of the saccule and utricle). We also estimated the density of dark and transitional cells in the lateral and posterior semicircular canals.

Results:

The loss of type I hair cells in the cristae of the superior, lateral, and posterior semicircular canals and in the maculae of the saccule and utricle was significantly higher in the hemorrhage group, as compared with the control group ( P < .05). The density of type II hair cells in the cristae of the superior and posterior canals and in the macula of the saccule significantly differed between the hemorrhage group and the control group ( P < .05).

Conclusion:

The loss of vestibular hair cells might be the cause of vestibular symptoms in patients with intralabyrinthine hemorrhage.

Haptoglobin increases the vulnerability of CD163-expressing neurons to hemoglobin

Haptoglobin (Hp) binds hemoglobin (Hb) with high affinity and provides the primary defense against its toxicity after intravascular hemolysis. Neurons are exposed to extracellular Hb after CNS hemorrhage, and a therapeutic effect of Hp via Hb sequestration has been hypothesized. In this study, we tested the hypothesis that Hp protects neurons from Hb in primary mixed cortical cell cultures. Treatment with low micromolar concentrations of human Hb for 24 h resulted in loss of 10-20% of neurons without injuring glia. Concomitant treatment with Hp surprisingly increased neuronal loss five-sevenfold, with similar results produced by Hp 1-1 and 2-2 phenotypes. Consistent with a recent in vivo observation, neurons expressed the CD163 receptor for Hb and the Hb-Hp complex in these cultures. Hp reduced overall Hb uptake, directed it away from the astrocyte-rich CD163-negative glial monolayer, and decreased induction of the iron-binding protein ferritin. Hb-Hp complex neuronal toxicity, like that of Hb per se, was iron-dependent and reduced by deferoxamine and 2,2' bipyridyl. These results suggest that Hp increases the vulnerability of CD163+ neurons to Hb by permitting Hb uptake while attenuating the protective response of ferritin induction by glial cells. Cover Image for this issue: doi: 10.1111/jnc.13342.

Hp: an inflammatory indicator in cardiovascular disease

Over the past decade significant advancement has occurred in the biological and pathological role that Hp has in cardiovascular disease. Hp is an acute-phase protein with a role in the neutralization and clearance of free heme. Iron has tremendous potential for initiating vascular oxidation, inflammation and exacerbating coronary atherosclerosis. Hp genotype has been linked as a prognostic biomarker of acute myocardial infarction, heart failure, restenosis and cardiac transplant rejection. The increased understanding of Hp as a biomarker has provided new insights into the mechanisms of inflammation after cardiac injury and support the concept that Hp is not only an important antioxidant in vascular inflammation and atherosclerosis, but also an enhancer of inflammation in cardiac transplant.

Role of Haptoglobin in Health and Disease: A Focus on Diabetes

In Brief Prospective identification of individuals with diabetes who are at greatest risk for developing complications would have considerable public health importance by allowing appropriate resources to be focused on those who would benefit most from aggressive intervention. Haptoglobin (Hp) is an acute-phase protein that is crucial for the elimination of free hemoglobin and the neutralization of oxidative damage. In the past two decades, associations have been made between polymorphisms in Hp and complications arising from diabetes. Individuals with polymorphism in Hp have been shown to have significantly higher risk of developing cardiovascular disease. This review summarizes the current literature on the role of Hp in health and disease, with a focus on diabetes.

Molecular pathophysiology of cerebral hemorrhage: secondary brain injury

Intracerebral hemorrhage (ICH) is an often fatal type of stroke that kills approximately 30,000 people annually in the United States. If the patient survives the ictus, then the resulting hematoma within brain parenchyma triggers a series of adverse events causing secondary insults and severe neurological deficits. This article discusses selected aspects of secondary brain injury after ICH and outlines key mechanisms associated with hematoma toxicity, oxidative stress, and inflammation. Finally, this review discusses the relevance of hematoma resolution processes as a target for ICH therapy and presents potential clinically relevant molecular targets that could be harnessed to treat secondary injury associated with ICH injury.

Impact of injury location and severity on posttraumatic epilepsy in the rat: role of frontal neocortex

Human posttraumatic epilepsy (PTE) is highly heterogeneous, ranging from mild remitting to progressive disabling forms. PTE results in simple partial, complex partial, and secondarily generalized seizures with a wide spectrum of durations and semiologies. PTE variability is thought to depend on the heterogeneity of head injury and patient's age, gender, and genetic background. To better understand the role of these factors, we investigated the seizures resulting from calibrated fluid percussion injury (FPI) to adolescent male Sprague-Dawley rats with video electrocorticography. We show that PTE incidence and the frequency and severity of chronic seizures depend on the location and severity of FPI. The frontal neocortex was more prone to epileptogenesis than the parietal and occipital, generating earlier, longer, and more frequent partial seizures. A prominent limbic focus developed in most animals, regardless of parameters of injury. Remarkably, even with carefully controlled injury parameters, including type, severity, and location, the duration of posttraumatic apnea and the age and gender of outbred rats, there was great subject-to-subject variability in frequency, duration, and rate of progression of seizures, indicating that other factors, likely the subjects' genetic background and physiological states, have critical roles in determining the characteristics of PTE.

Neuroprotective role of haptoglobin after intracerebral hemorrhage

After intracerebral hemorrhage (ICH), the brain parenchyma is exposed to blood containing red blood cells (RBCs) and consequently to its lysis products. Iron-rich hemoglobin (Hb) is the most abundant protein in RBCs. When released into the brain parenchyma during hemolysis, Hb becomes a central mediator of cytotoxicity. Our study indicates that haptoglobin (Hp), an acute-phase response protein primarily synthesized in the liver and known to bind and neutralize Hb in the bloodstream, is also expressed in brain in which it plays an important role in defending neurons from damage induced by hemolytic products after ICH. We demonstrate that the Hb-induced hypohaptoglobinemia aggravates ICH-induced brain damage while pharmacologic intervention with sulforaphane to induce brain Hp is linked to a reduction in brain damage. In agreement with these findings, Hp deficiency worsens whereas Hp overexpression alleviates ICH-mediated brain injury. We also identified that oligodendroglia are the primary source of brain-derived Hp among brain cells and that oligodendroglia-released Hp plays protective roles against Hb-mediated toxicity to neurons and oligodendrocytes. We conclude that Hp, particularly the brain-derived Hp, plays cytoprotective roles and represents a potential therapeutic target for ICH treatment.

Haptoglobin phenotype and apolipoprotein E polymorphism: relationship to posttraumatic seizures and neuropsychological functioning after traumatic brain injury

The relationship of genetic predisposition to reduced iron capacity and apolipoprotein E (APOE) to posttraumatic seizures (PTSs) and neuropsychological outcomes was investigated in patients with traumatic brain injuries from a prior valproate clinical study. Haptoglobin concentration/phenotype and APOE genotype were determined in 25 patients with PTSs and 26 control (no PTSs) subjects approximately 10 years after traumatic brain injury. Haptoglobin phenotype was also determined in previously collected frozen samples for 25 additional patients with PTSs and 32 no-PTS subjects. There was no relationship between haptoglobin phenotype or APOE genotype and occurrence of PTSs. APOE genotype was not related to neuropsychological outcome; however, when adjustments were made for differences in educational levels, APOE epsilon4 subjects did worse, especially on tests of verbal intellectual and verbal memory skills. In contrast to our hypothesis, those with haptoglobin 1-1 (high-affinity binder of hemoglobin) scored somewhat worse on Verbal IQ and Tapping D at 1 and 12 months after injury.

On the fate of extracellular hemoglobin and heme in brain

Intracerebral hemorrhage (ICH) is a major cause of disability in adults worldwide. The pathophysiology of this syndrome is complex, involving both inflammatory and redox components triggered by the extravasation of blood into the cerebral parenchyma. Hemoglobin, heme, and iron released therein seem be important in the brain damage observed in ICH. However, there is a lack of information concerning hemoglobin traffic and metabolism in brain cells. Here, we investigated the fate of hemoglobin and heme in cultured neurons and astrocytes, as well as in the cortex of adult rats. Hemoglobin was made traceable by conjugation to Alexa 488, whereas a fluorescent heme analogue (tin-protoporphyrin IX) was prepared to allow heme tracking. Using fluorescence microscopy we observed that neurons were more efficient in uptake hemoglobin and heme than astrocytes. Exposure of cortical neurons to hemoglobin or heme resulted in an oxidative stress condition. Viability assays showed that neurons were more susceptible to both hemoglobin and heme toxicity than astrocytes. Together, these results show that neurons, rather than astrocytes, preferentially take up hemoglobin-derived products, indicating that these cells are actively involved in the ICH-associated brain damage.

Haptoglobin HP2-2 genotype, alpha-thalassaemia and acute seizures in children living in a malaria-endemic area

Polymorphisms of the haptoglobin (HP) gene and deletions in alpha-globin gene (alpha-thalassaemia) are common in malaria-endemic Africa. The same region also has high incidence rates for childhood acute seizures. The haptoglobin HP2-2 genotype has been associated with idiopathic generalized epilepsies and altered iron metabolism in children with alpha-thalassaemia can potentially interfere with neurotransmission and increase the risk of seizures. We investigated the hypothesis that the HP2-2 genotype and the common African alpha-globin gene deletions are associated with the increased risk of seizures. 288 children aged 3-156 months admitted with acute seizures to Kilifi District Hospital (Kenya), were matched for ethnicity to an equal number of community controls. The proportion of cases (72/288 [25.0%]) and controls (80/288 [27.8%]) with HP2-2 genotype was similar, p=0.499. The allele frequency of HP2 gene in cases (49.3%) and controls (48.6%) was also similar, p=0.814. Similarly, we found no significant difference between the proportion of cases (177/267 [66.3%]) and controls (186/267 [69.7%]) with deletions in alpha-globin gene (p=0.403). Among cases, HP2-2 polymorphism and deletions in alpha-globin gene were neither associated with changes in the type, number or duration of seizures nor did they affect outcome. We conclude that the HP2-2 polymorphism and deletions in alpha-globin gene are not risk factors for acute seizures in children. Future studies should examine other susceptibility genes.

Haptoglobin study in myasthenia gravis

OBJECTIVE: A cross-sectional study of haptoglobin (Hp) in myasthenia gravis (MG) was designed, with the objective to identify its values and correlate them with different disease status. METHOD: 46 patients were enrolled in the study, all having disease severity established according to the quantitative myasthenia gravis strength scores (QMGSS). Based on the functional scale determined by Myasthenia Gravis Foundation of America (MGFA) recommendations, patients were classified as having: complete stable remission (CSR; n=10); minimal manifestations-0 (MM0; n=6), minimal manifestations-1 (MM1; n=4); pharmacological remission (PR; n=6). Two other groups participated: thymomatous patients (T; n=10) and patients without imunosuppression or thymectomy, until the assessment for Hp (WIT; n=10). Hp dosage was done by immunonephelometry, blindly to clinical data. Student's t-test, Anova test and linear regression were employed for statistical analyses. RESULTS: Statistically significant differences occurred between CSR+MM0xWIT groups (86.62x157.57, p<0.001) and PR+MM1xWIT groups (73.93x157.57, p<0.001). Linear regression showed correlation between Hp levels and QMGSS (r=0.759, p<0.001). CONCLUSION: Our results suggest that Hp may be useful in clinical practice as a disease severity marker in MG.

Haptoglobin: a review of the major allele frequencies worldwide and their association with diseases

Haptoglobin (Hp) is a plasma alpha(2)-glycoprotein which binds free haemoglobin, thus preventing oxidative damage. The complex is rapidly removed from the circulation by a specific receptor (CD163) found on macrophages. Three major subtypes, Hp1-1, Hp2-1 and Hp2-2 are the product of two closely related genes HP(1) and HP(2). The frequency of the HP(1) and HP(2) genes varies worldwide depending on racial origin: the HP(1)frequency varying from about 0.07 in parts of India to over 0.7 in parts of West Africa and South America. Both HP(1) and HP(2) have been linked to susceptibility to various diseases. Such associations may be explained by functional differences between the subtypes in the binding of Hb and its rate of clearance from the plasma. However, there are also corresponding negative reports for disease associations. The conflicting evidence on disease association and the lack of association between disease and particular populations, despite the wide range of HP(1) and HP(2) gene frequencies across the world, may indicate that any associations are marginal.

Effect of heme oxygenase-1 on the vulnerability of astrocytes and neurons to hemoglobin

The heme oxygenase (HO) enzymes catalyze the rate-limiting step of heme breakdown. Prior studies have demonstrated that the vulnerability of neurons and astrocytes to hemoglobin is modified in cells lacking HO-2, the constitutive isoform. The present study assessed the effect of the inducible isoform, HO-1. Wild-type astrocytes treated for 3-5 days with 3-30 microM hemoglobin sustained no loss of viability, as quantified by LDH and MTT assays. The same treatment resulted in death of 25-50% of HO-1 knockout astrocytes, and a 4-fold increase in protein oxidation. Cell injury was attenuated by transfer of the HO-1 gene, but not by bilirubin, the antioxidant heme breakdown product. Conversely, neuronal protein oxidation and cell death after hemoglobin exposure were similar in wild-type and HO-1 knockout cultures. These results suggest that HO-1 induction protects astrocytes from the oxidative toxicity of Hb, but has no effect on neuronal injury.

Epilepsy after head injury

PURPOSE OF REVIEW

The purpose of this short review is to provide an update on the epidemiology of posttraumatic epilepsy, associated risk factors, data from prevention studies, and recent breakthroughs in experimental research.

RECENT FINDINGS

There is increasing evidence that neuroimaging findings, stratification by neurosurgical procedures performed, and genomic information (e.g. apolipoprotein E and haptoglobin genotypes) may provide useful predictors of the individual risk of developing posttraumatic epilepsy. While antiepileptic drug prophylaxis can be effective in protecting against acute (provoked) seizures occurring within 7 days after injury, no antiepileptic drug treatment has been found to protect against the development of posttraumatic epilepsy and therefore long-term anticonvulsant prophylaxis is not recommended. Glucocorticoid administration early after head injury also has not been found to reduce the risk of posttraumatic epilepsy. At the basic research level, there have been advances in the understanding of pathophysiological changes in posttraumatic excitatory and inhibitory synapses, and the critical period for epileptogenesis after head injury has been better defined. Finally, the development of a novel animal model, which mimicks more closely human posttraumatic epilepsy, may facilitate efforts to characterize relevant epileptogenic mechanisms and to identify clinically effective antiepileptogenic treatments.

SUMMARY

Despite the continuing lack of clinically effective agents for posttraumatic epilepsy prophylaxis, recent advances in basic and clinical research offer new hope for success in the development of new strategies for prevention and treatment.

Haptoglobin polymorphisms and iron homeostasis in health and in disease

Haptoglobin (Hpt) is a plasma protein with hemoglobin-binding capacity. It is a well-known marker of hemolysis. Hpt is also an acute-phase protein that functions as a bacteriostatic agent, an inhibitor of prostaglandin synthesis and angiogenesis. However, the best-known biological function of Hpt is capture of hemoglobin (Hb). The identification of functional differences in haptoglobin molecules resulting from relatively common polymorphisms has further elucidated the importance of haptoglobin in iron homeostasis and in disease processes influenced by iron metabolism. In this review the effect of Hpt polymorphism on these different disease entities will be discussed.

Role of free radicals in the neurodegenerative diseases: therapeutic implications for antioxidant treatment

Free radicals and other so-called 'reactive species' are constantly produced in the brain in vivo. Some arise by 'accidents of chemistry', an example of which may be the leakage of electrons from the mitochondrial electron transport chain to generate superoxide radical (O2*-). Others are generated for useful purposes, such as the role of nitric oxide in neurotransmission and the production of O2*- by activated microglia. Because of its high ATP demand, the brain consumes O2 rapidly, and is thus susceptible to interference with mitochondrial function, which can in turn lead to increased O2*- formation. The brain contains multiple antioxidant defences, of which the mitochondrial manganese-containing superoxide dismutase and reduced glutathione seem especially important. Iron is a powerful promoter of free radical damage, able to catalyse generation of highly reactive hydroxyl, alkoxyl and peroxyl radicals from hydrogen peroxide and lipid peroxides, respectively. Although most iron in the brain is stored in ferritin, 'catalytic' iron is readily mobilised from injured brain tissue. Increased levels of oxidative damage to DNA, lipids and proteins have been detected by a range of assays in post-mortem tissues from patients with Parkinson's disease, Alzheimer's disease and amyotrophic lateral sclerosis, and at least some of these changes may occur early in disease progression. The accumulation and precipitation of proteins that occur in these diseases may be aggravated by oxidative damage, and may in turn cause more oxidative damage by interfering with the function of the proteasome. Indeed, it has been shown that proteasomal inhibition increases levels of oxidative damage not only to proteins but also to other biomolecules. Hence, there are many attempts to develop antioxidants that can cross the blood-brain barrier and decrease oxidative damage. Natural antioxidants such as vitamin E (tocopherol), carotenoids and flavonoids do not readily enter the brain in the adult, and the lazaroid antioxidant tirilazad (U-74006F) appears to localise in the blood-brain barrier. Other antioxidants under development include modified spin traps and low molecular mass scavengers of O2*-. One possible source of lead compounds is the use of traditional remedies claimed to improve brain function. Little is known about the impact of dietary antioxidants upon the development and progression of neurodegenerative diseases, especially Alzheimer's disease. Several agents already in therapeutic use might exert some of their effects by antioxidant action, including selegiline (deprenyl), apomorphine and nitecapone.

Haptoglobin polymorphism and body iron stores

In humans the iron status is influenced by environmental and genetic factors. Among them, the genetic polymorphism of the hemoglobin (Hb)-binding plasma protein haptoglobin (Hp) has been shown to affect iron turnover. The best known biological function of Hp is capture of free Hb in plasma to allow hepatic recycling of heme iron and to prevent kidney damage during hemolysis. In healthy males, but not in females, the Hp 2-2 phenotype is associated with higher serum iron, higher transferrin saturation, and higher ferritin than Hp 1-1 and 2-1. Moreover, serum ferritin correlates with monocyte L-ferritin content, which is also highest in Hp 2-2 subjects due to endocytosis of multimeric Hb-Hp 2-2 complexes by the recently identified Hb scavenger receptor CD163 in macrophages. This iron delocalization pathway, occurring selectively in Hp 2-2 subjects, has important biological and clinical consequences. The Hp polymorphism is related to the prevalence and the outcome of various pathological conditions with altered iron metabolism such as hemochromatosis, infections, and atherosclerotic vascular disease.

Effectiveness of washed platelet concentrate and red cell transfusions for a patient with anhaptoglobinemia with antihaptoglobin antibody

A 71-year-old Japanese male with myelodysplastic syndrome progressing to overt leukaemia and hepatocellular carcinoma developed dyspnea and urticaria immediately after infusion of platelet concentrate (PC). He exhibited an identical reaction following blood transfusion. Serum haptoglobin was undetectable. The patient was determined to be homozygous for Hp(del) by polymerase chain reaction (PCR). Antibody to haptoglobin was detected by enzyme-linked immunosorbent assay (ELISA) and Western blot analysis. No antibodies against human leucocyte antigen (HLA) or platelet-specific antigens were detected. Washed PC and washed red blood cells were effective in preventing the transfusion-related anaphylactoid reactions.

The Haptoglobin 2-2 Phenotype Affects Serum Markers of Iron Status in Healthy Males

Background: Human iron status is influenced by environmental and genetic factors. We hypothesized that the genetic polymorphism of haptoglobin (Hp), a hemoglobin-binding plasma protein, could affect iron status.

Methods: Reference values of serum iron status markers were compared according to Hp phenotypes (Hp 1-1, Hp 2-1, Hp 2-2; determined by starch gel electrophoresis) in 717 healthy adults. Iron storage was investigated in peripheral blood monocyte-macrophages by measuring cytosolic L- and H-ferritins and by in vitro uptake of radiolabeled (125I) hemoglobin-haptoglobin complexes.

Results: In males but not in females, the Hp 2-2 phenotype was associated with higher serum iron (P &lt;0.05), transferrin saturation (P &lt;0.05), and ferritin (P &lt;0.01) concentrations than Hp 1-1 and 2-1, whereas soluble transferrin receptor concentrations were lower (P &lt;0.05). Moreover, serum ferritin correlated with monocyte L-ferritin content (r = 0.699), which was also highest in the male Hp 2-2 subgroup (P &lt;0.01). In vitro, monocyte-macrophages took up a small fraction of 125I-labeled hemoglobin complexed to Hp 2-2 but not to Hp 1-1 or 2-1.

Conclusions: The Hp 2-2 phenotype affects serum iron status markers in healthy males and is associated with higher L-ferritin concentrations in monocyte-macrophages because of a yet undescribed iron delocalization pathway, selectively occurring in Hp 2-2 subjects.

Profiling of endogenous peptides as a tool for studying development and neurological disease

The use of a method to follow changes in endogenous peptide production, as they occur in biological studies, is an excellent complement to other molecular techniques. It has the unique ability to characterize peptides that have been produced from protein precursors, and instrumentation is available that provides high resolution peptide separations that are quantitative, sensitive, and amenable to automation. All tissues express a large number of peptide species that can be visualized, or profiled, on chromatographic separations using reverse-phase high-performance liquid chromatography. This large number of peptides offers many potential molecules that can be used to identify biological mechanisms associated with experimental paradigms. Peptide analysis has been used successfully in many types of studies. In this review, we outline our experience in using peptides as biological markers and provide a description of the evolution of peptide profiling in our laboratories. Peptide expression has been used in studies ranging from how brain regions develop to identifying changes in disease processes including Alzheimer's disease and models of stroke. Some of the findings provided by these studies have been new pathways of peptide processing and the identification of accelerated proteolysis on proteins such as hemoglobin as a function of Alzheimer's disease and brain insult. Peptide profiling has also proven to be an excellent technique for studying many well-known nervous system proteins including calmodulin, PEP-19, myelin basic protein, cytoskeletal proteins, and others. It is the purpose of this review to describe our experience using the technique and to highlight improvements that have added to the power of the approach. Peptide analysis and the expansion in the instrumentation that can detect peptides will no doubt make these types of studies a powerful addition to our molecular armamentarium for conducting biological studies.

Hemoglobin and iron-evoked oxidative stress in the brain: protection by bile pigments, manganese and S-nitrosoglutathione

In the present in vitro and in vivo study we investigated the pro-oxidant effects of hemoglobin, as well as the antioxidant effects of its metabolites, in the brain. Incubation of rat brain homogenates with hemoglobin (0-10 microM) but not hemin induced lipid peroxidation up to 24 h (EC50 = 1.2 microM). Hemoglobin's effects were similar to ferrous ion (EC50 = 1.7 microM) and were blocked by the chelating agent deferoxamine (IC50 0.5 microM) and a nitric oxide-releasing compound S-nitrosoglutathione (IC50 = 40 microM). However, metabolites of hemoglobin - biliverdin and bilirubin - inhibited brain lipid peroxidation induced by cell disruption and hemoglobin (biliverdin IC50 = 12-30 and bilirubin IC50 = 75-170 microM). Biliverdin's antioxidative effects in spontaneous and iron-evoked lipid peroxidation were further augmented by manganese (2 microM) since manganese is an antioxidative transition metal and conjugates with bile pigments. Intrastriatal infusion of hemoglobin (0-24 nmol) produced slight, but significant 20-22% decreases in striatal dopamine levels. Whereas, intrastriatal infusion of ferrous citrate (0-24 nmol) dose-dependently induced a greater 66% depletion of striatal dopamine which was preceded by an acute increase of lipid peroxidation. In conclusion, contrary to the in vitro results hemoglobin is far less neurotoxic than ferrous ions in the brain. It is speculated that hemoglobin may be partially detoxified by heme oxygenase and biliverdin reductase to its antioxidative metabolites in the brain. However, in head trauma and stroke, massive bleeding could significantly produce iron-mediated oxidative stress and neurodegeneration which could be minimized by endogenous antioxidants such as biliverdin, bilirubin, manganese and S-nitrosoglutathione.

Free radicals in inflammatory neurological disease: increased lipid peroxidation and haptoglobin levels in Guillain Barré syndrome

Oxidative damage in three inflammatory neurological disorders; Guillain Barré syndrome (GBS), multiple sclerosis and aseptic meningitis, were assessed by measuring the peroxidation of lipids in body fluids. The results were compared to a control group consisting of patients with either migraine, chronic/tension headaches, benign intracranial hypertension or psychological disorders. Antioxidant status was assessed by the measurement of the extracellular proteins, haptoglobin, albumin, caeruloplasmin and transferrin. The results of the study suggested that firstly, haptoglobin levels might be a useful, easily obtainable marker to aid the diagnosis of GBS. Secondly, free radical damage may be implicated in the pathology of GBS and therefore appropriate free radical scavenging might have beneficial effects.

Oxidation of low-density lipoprotein by hemoglobin stems from a heme-initiated globin radical: antioxidant role of haptoglobin

Hemoglobin, known as a poor peroxidase, has been recently found to be a highly reactive catalyzer of low-density lipoprotein (LDL) oxidation resulting in oxidation of LDL lipids and covalent cross-linking of the LDL protein, apo B. We evaluated three possible mechanisms that may account for hemoglobin reactivity: oxidative activation by globin-dissociated hemin following its transfer to LDL; peroxidase-like reactivity of the ferryl iron active state in intact hemoglobin; and oxidation by a globin radical formed in oxidized hemoglobin. The first mechanism was ruled out because only a minor fraction of hemin was actually transferred to LDL in the process of oxidation. The second mechanism was excluded because hemoglobin ferryl, unlike ferryl of horseradish peroxidase, was not consumed in the process of LDL oxidation. Haptoglobin completely inhibited cross-linking of globin in hemoglobin/H2O2 mixtures but not in myglobin/H2O2, as well as cross-linking of apo B and oxidation of LDL lipids. Haptoglobin could not however abolish the hemoglobin ferryl state, a finding that further supported exclusion of the second mechanism. We conclude that the active species in hemoglobin-induced LDL oxidation is the globin radical, as suggested in the third mechanism. The present findings also show that haptoglobin functions as a major antioxidant thus protecting the vascular system.

Epilepsy

Diagnosis and management of the epilepsies are routinely performed by primary care physicians. In the United States, only 17% of patients with new-onset epilepsy are examined by neurologic specialists, and even fewer patients employ neurologists for their ongoing care. With the changes dictated by the evolving health care system in the United States, the responsibilities for the treatment of patients with epilepsies by primary care physicians will continue to increase. At the same time, there has been an explosion of new information about the diagnosis, evaluation, natural history, and neurobiologic aspects of epilepsy. New medical and surgical treatments are being introduced with a quickening pace. Finally, the concept that certain epilepsies may be progressive and that early identification and aggressive treatment represent one's best chance for establishing control for these patients has gained widespread confirmation from both clinical and animal model studies. The past standard of care is quickly ending. No longer should a patient or a physician accept only partial seizure control. This monograph attempts to lay the basis for improved understanding of epilepsy so that our patients will be seizure free without side effects and will be able to fully participate in our society.

Current status of antioxidant therapy

There is evidence that free radical damage contributes to the aetiology of many chronic health problems such as emphysema, cardiovascular and inflammatory diseases, cataracts, and cancer. In this review we are not concerned with tissue damage in vivo induced directly by radicals from exogenous sources, such as air pollutants and tobacco smoke, high-pressure oxygen, irradiation, or through the metabolism of certain solvents, drugs, and pesticides. Rather, we address some of the disease states associated with increased oxidative stress from endogenous sources and the possible therapeutic advantage of the antioxidant treatment. This raises the question of the antioxidant status of individuals and its role in protection against amplification of certain disease processes. We have chosen to concentrate mainly on coronary heart disease, reperfusion injury, and organ storage for transplantation.

Dextran-coupled deferoxamine improves outcome in a murine model of head injury

Tissue damage involving oxygen-derived free radicals may be greatly exacerbated by free, reactive iron, which acts as a catalyst in oxidative reactions. The effects of free iron can be attenuated by the administration of deferoxamine (DFO), an iron chelator. However, DFO has limited therapeutic utility because it has a short plasma half-life (approximately 5.5 min in mice) and produces profound hypotension upon intravenous infusion. These negative attributes have been circumvented by the covalent attachment of DFO to large polymers, such as dextran or hydroxyethyl starch. The ability of the dextran-conjugated DFO (DEX-DFO) to inhibit iron-catalyzed reactions with lipids was compared to that of the native molecule in an in vitro model of CNS lipid degradation in the presence of 200 microM ferrous iron. There was no difference between native DFO and the modified form. Modified and unmodified DFO were also compared for therapeutic efficacy in a murine model of head injury. Using a previously described "grip test" as a measure of neurologic impairment following injury, DEX-DFO, native DFO, and dextran were administered intravenously 3-5 min after injury. Dextran-DFO significantly decreased the incidence of severe neurologic impairment at dosage levels of 0.1 (n = 92), 1.0 (n = 76), and 10.0 (n = 80) mg/kg. Administration of native DFO or dextran had no effect at the same dosages and concentrations. These results suggest that the murine model of head injury contains a significant iron-dependent component that should be assessed in other models of neural injury.

Relationships of haptoglobin level to FEV1, wheezing, bronchial hyper-responsiveness and allergy

The relationships of haptoglobin level to respiratory and allergic parameters have been assessed in an epidemiological study conducted in a working population surveyed twice 5 years apart. At the first survey conducted in 892 working men, haptoglobin level was significantly related to FEV1 (r = -0.18; P less than 0.001) and smoking habits. After adjustment for smoking, a history of wheezing was significantly related to lower haptoglobin level. A second survey conducted in 304 men of the original sample 5 years later confirmed that haptoglobin was related to FEV1 (r = -0.21; P less than 0.001) and that wheezing was significantly related to hypohaptoglobinaemia (lower decile; P = 0.04). Men who exhibited bronchial hyper-responsiveness to methacholine had haptoglobin levels 0.35 g/l higher than those who did not (P = 0.01). Haptoglobin level was unrelated to IgE level and skin prick tests. These results support the hypothesis of the role of inflammation in both lower lung function and bronchial hyper-responsiveness. They suggest that some heterogeneity exists within subjects with a history of wheezing.

Iron-induced lipid peroxidation and brain injury responses

Head trauma with cerebral contusion causes extravasation of red blood cells, followed by hemolysis and deposition of iron-containing blood products within the neuropil. Liberation of heme compounds is associated with deposition of hemosiderin, and with gliosis, neuronal loss and occasionally the development of seizures. In this experiment we injected components of red blood cell contents into rat amygdala, and then measured the rate of appearance of products of lipid peroxidation. Injection of microliter volumes of hemin and hemoglobin, with hematoprotoporphyrin and rodent plasma injection and contralateral uninjected tissue as controls, showed that the presence of the iron moiety within the protoporphyrin ring was required to initiate and propagate peroxidation. Free radical reactions initiated by iron or heme deposited within the neuropil may be a fundamental reaction associated with brain injury responses, and possibly with posttraumatic epileptogenesis.