Plasma proteins in edematous white matter after intracerebral hemorrhage confound immunoblots: an ELISA to quantify contamination

Relevance of Porcine Stroke Models to Bridge the Gap from Pre-Clinical Findings to Clinical Implementation

In the search of animal stroke models providing translational advantages for biomedical research, pigs are large mammals with interesting brain characteristics and wide social acceptance. Compared to rodents, pigs have human-like highly gyrencephalic brains. In addition, increasingly through phylogeny, animals have more sophisticated white matter connectivity; thus, ratios of white-to-gray matter in humans and pigs are higher than in rodents. Swine models provide the opportunity to study the effect of stroke with emphasis on white matter damage and neuroanatomical changes in connectivity, and their pathophysiological correlate. In addition, the subarachnoid space surrounding the swine brain resembles that of humans. This allows the accumulation of blood and clots in subarachnoid hemorrhage models mimicking the clinical condition. The clot accumulation has been reported to mediate pathological mechanisms known to contribute to infarct progression and final damage in stroke patients. Importantly, swine allows trustworthy tracking of brain damage evolution using the same non-invasive multimodal imaging sequences used in the clinical practice. Moreover, several models of comorbidities and pathologies usually found in stroke patients have recently been established in swine. We review here ischemic and hemorrhagic stroke models reported so far in pigs. The advantages and limitations of each model are also discussed.

White Matter Injury and Recovery after Hypertensive Intracerebral Hemorrhage

Hypertensive intracerebral hemorrhage (ICH) could very probably trigger white matter injury in patients. Through the continuous study of white matter injury after hypertensive ICH, we achieve a more profound understanding of the pathophysiological mechanism of its occurrence and development. At the same time, we found a series of drugs and treatment methods for the white matter repair. In the current reality, the research paradigm of white matter injury after hypertensive ICH is relatively obsolete or incomplete, and there are still lots of deficiencies in the research. In the face of the profound changes of stroke research perspective, we believe that the combination of the lenticulostriate artery, nerve nuclei of the hypothalamus-thalamus-basal ganglia, and the white matter fibers located within the capsula interna will be beneficial to the research of white matter injury and repair. This paper has classified and analyzed the study of white matter injury and repair after hypertensive ICH and also rethought the shortcomings of the current research. We hope that it could help researchers further explore and study white matter injury and repair after hypertensive ICH.

Estrogen-IGF-1 interactions in neuroprotection: ischemic stroke as a case study

The steroid hormone 17b-estradiol and the peptide hormone insulin-like growth factor (IGF)-1 independently exert neuroprotective actions in neurologic diseases such as stroke. Only a few studies have directly addressed the interaction between the two hormone systems, however, there is a large literature that indicates potentially greater interactions between the 17b-estradiol and IGF-1 systems. The present review focuses on key issues related to this interaction including IGF-1 and sex differences and common activation of second messenger systems. Using ischemic stroke as a case study, this review also focuses on independent and cooperative actions of estrogen and IGF-1 on neuroprotection, blood brain barrier integrity, angiogenesis, inflammation and post-stroke epilepsy. Finally, the review also focuses on the astrocyte, a key mediator of post stroke repair, as a local source of 17b-estradiol and IGF-1. This review thus highlights areas where significant new research is needed to clarify the interactions between these two neuroprotectants.

Age-related changes in brain support cells: Implications for stroke severity

Stroke is one of the leading causes of adult disability and the fourth leading cause of mortality in the US. Stroke disproportionately occurs among the elderly, where the disease is more likely to be fatal or lead to long-term supportive care. Animal models, where the ischemic insult can be controlled more precisely, also confirm that aged animals sustain more severe strokes as compared to young animals. Furthermore, the neuroprotection usually seen in younger females when compared to young males is not observed in older females. The preclinical literature thus provides a valuable resource for understanding why the aging brain is more susceptible to severe infarction. In this review, we discuss the hypothesis that stroke severity in the aging brain may be associated with reduced functional capacity of critical support cells. Specifically, we focus on astrocytes, that are critical for detoxification of the brain microenvironment and endothelial cells, which play a crucial role in maintaining the blood brain barrier. In view of the sex difference in stroke severity, this review also discusses studies of middle-aged acyclic females as well as the effects of the estrogen on astrocytes and endothelial cells.

Reproductive age-related changes in the blood brain barrier: expression of IgG and tight junction proteins

We previously demonstrated that there is a significantly greater transfer of intravenously-injected Evan's blue dye into the forebrain of acyclic (reproductive senescent) females compared to young adult females, indicating that blood brain barrier permeability is compromised in the reproductive senescent forebrain. The present study examined brain IgG expression and microvessel tight junction proteins to assess ovarian age-related changes in microvascular permeability, and further compared young and senescent females with age-matched males to distinguish changes attributable to age and reproductive senescence. Blood brain barrier breakdown are often associated with increased extravasation of plasma proteins and high levels of immunoglobulin G (IgG) in brain. In the present study, IgG expression was dramatically increased in the hippocampus and thalamus, but not the hypothalamus of reproductive senescent females compared to young adult females. In males, IgG expression was increased in all these regions in middle-aged animals (aged-matched to senescent females) as compared to young males (age-matched to the young adult females). Furthermore, the proportion of hippocampal microvessels with perivascular IgG immunoreactivity was significantly greater in reproductive senescent females as compared to young adult females, while middle-aged males and young adult males did not differ. The tight junctions between adjacent microvascular endothelial cells regulated by transmembrane proteins such as claudin-5 and occludin play a critical role in maintaining the blood brain barrier integrity. Increased hippocampal IgG expression in senescent females was paralleled by poor junctional localization of the tight junction protein claudin-5 in hippocampal microvessels. However, there was no difference in hippocampal claudin-5 localization between young adult and middle-aged males, indicating that dysregulation of this junctional protein was associated with ovarian aging. Parallel studies in human brain microvessels also revealed age-dependent disruption in claudin-5 distribution in post-menopausal women compared to pre-menopausal women. Collectively, these data support the hypothesis that constitutive loss of barrier integrity in the forebrain during reproductive senescence may be due, in part, to the selective loss of tight junction proteins in endothelial junctions.

Bilirubin oxidation products, oxidative stress, and intracerebral hemorrhage

Hematoma and perihematomal regions after intracerebral hemorrhage (ICH) are biochemically active environments known to undergo potent oxidizing reactions. We report facile production of bilirubin oxidation products (BOXes) via hemoglobin/Fenton reaction under conditions approximating putative in vivo conditions seen following ICH. Using a mixture of human hemoglobin, physiological buffers, unconjugated solubilized bilirubin, and molecular oxygen and/or hydrogen peroxide, we generated BOXes, confirmed by spectral signature consistent with known BOXes mixtures produced by independent chemical synthesis, as well as HPLC-MS of BOX A and BOX B. Kinetics are straightforward and uncomplicated, having initial rates around 0.002 microM bilirubin per microM hemoglobin per second under normal experimental conditions. In hematomas from porcine ICH model, we observed significant production of BOXes, malondialdehyde, and superoxide dismutase, indicating a potent oxidizing environment. BOX concentrations increased from 0.084 +/- 0.01 in fresh blood to 22.24 +/- 4.28 in hematoma at 72h, and were 11.22 +/- 1.90 in adjacent white matter (nmol/g). Similar chemical and analytical results are seen in ICH in vivo, indicating the hematoma is undergoing similar potent oxidations. This is the first report of BOXes production using a well-defined biological reaction and in vivo model of same. Following ICH, amounts of unconjugated bilirubin in hematoma can be substantial, as can levels of iron and hemoglobin. Oxidation of unconjugated bilirubin to yield bioactive molecules, such as BOXes, is an important discovery, expanding the role of bilirubin in pathological processes seen after ICH.

A novel duplex ELISA method for quantitation of plasma proteins in areas of brain edema

We have developed a novel type of duplex enzyme-linked immunosorbent assay (ELISA) for the quantitation of the major plasma proteins, IgG and albumin, in edematous brain tissue. We test this duplex ELISA on our porcine intracerebral hemorrhage (ICH) model and show that it is as accurate and sensitive as independent single ELISAs. This method is useful as a marker of edema in brain tissue and the same design can be applied to other proteins and sample types.