Acute-phase proteins before cerebral ischemia in stroke-prone rats: identification by proteomics

Comprehensive Assessment of Ischemic Stroke in Nonhuman Primates: Neuroimaging, Behavioral, and Serum Proteomic Analysis

Ischemic strokes, prevalence and impactful, underscore the necessity of advanced research models closely resembling human physiology. Our study utilizes nonhuman primates (NHPs) to provide a detailed exploration of ischemic stroke, integrating neuroimaging data, behavioral outcomes, and serum proteomics to elucidate the complex interplay of factors involved in stroke pathophysiology. We observed a consistent pattern in infarct volume, peaking at 1-month postmiddle cerebral artery occlusion (MCAO) and then stabilized. This pattern was strongly correlated to notable changes in motor function and working memory performance. Using diffusion tensor imaging (DTI), we detected significant alterations in fractional anisotropy (FA) and mean diffusivity (MD) values, signaling microstructural changes in the brain. These alterations closely correlated with the neurological and cognitive deficits that we observed, highlighting the sensitivity of DTI metrics in stroke assessment. Behaviorally, the monkeys exhibited a reliance on their unaffected limb for compensatory movements, a common response to stroke impairment. This adaptation, along with consistent DTI findings, suggests a significant impact of stroke on motor function and spatial perception. Proteomic analysis through MS/MS functional enrichment identified two distinct groups of proteins with significant changes post-MCAO. Notably, MMP9, THBS1, MB, PFN1, and YWHAZ were identified as potential biomarkers and therapeutic targets for ischemic stroke. Our results underscore the complex nature of stroke and advocate for an integrated approach, combining neuroimaging, behavioral studies, and proteomics, for advancing our understanding and treatment of this condition.

Multi-omics Combined with Machine Learning Facilitating the Diagnosis of Gastric Cancer

Gastric cancer (GC) is a highly intricate gastrointestinal malignancy. Early detection of gastric cancer forms the cornerstone of precision medicine. Several studies have been conducted to investigate early biomarkers of gastric cancer using genomics, transcriptomics, proteomics, and metabolomics, respectively. However, endogenous substances associated with various omics are concurrently altered during gastric cancer development. Furthermore, environmental exposures and family history can also induce modifications in endogenous substances. Therefore, in this study, we primarily investigated alterations in DNA mutation, DNA methylation, mRNA, lncRNA, miRNA, circRNA, and protein, as well as glucose, amino acid, nucleotide, and lipid metabolism levels in the context of GC development, employing genomics, transcriptomics, proteomics, and metabolomics. Additionally, we elucidate the impact of exposure factors, including HP, EBV, nitrosamines, smoking, alcohol consumption, and family history, on diagnostic biomarkers of gastric cancer. Lastly, we provide a summary of the application of machine learning in integrating multi-omics data. Thus, this review aims to elucidate: i) the biomarkers of gastric cancer related to genomics, transcriptomics, proteomics, and metabolomics; ii) the influence of environmental exposure and family history on multiomics data; iii) the integrated analysis of multi-omics data using machine learning techniques.

Multi-omics research strategies in ischemic stroke: A multidimensional perspective

Ischemic stroke (IS) is a multifactorial and heterogeneous neurological disorder with high rate of death and long-term impairment. Despite years of studies, there are still no stroke biomarkers for clinical practice, and the molecular mechanisms of stroke remain largely unclear. The high-throughput omics approach provides new avenues for discovering biomarkers of IS and explaining its pathological mechanisms. However, single-omics approaches only provide a limited understanding of the biological pathways of diseases. The integration of multiple omics data means the simultaneous analysis of thousands of genes, RNAs, proteins and metabolites, revealing networks of interactions between multiple molecular levels. Integrated analysis of multi-omics approaches will provide helpful insights into stroke pathogenesis, therapeutic target identification and biomarker discovery. Here, we consider advances in genomics, transcriptomics, proteomics and metabolomics and outline their use in discovering the biomarkers and pathological mechanisms of IS. We then delineate strategies for achieving integration at the multi-omics level and discuss how integrative omics and systems biology can contribute to our understanding and management of IS.

Salt loading decreases urinary excretion and increases intracellular accumulation of uromodulin in stroke-prone spontaneously hypertensive rats

Uromodulin (UMOD) is the most abundant renal protein secreted into urine by the thick ascending limb (TAL) epithelial cells of the loop of Henle. Genetic studies have demonstrated an association between UMOD risk variants and hypertension. We aimed to dissect the role of dietary salt in renal UMOD excretion in normotension and chronic hypertension. Normotensive Wistar-Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP) (n=8/sex/strain) were maintained on 1% NaCl for 3 weeks. A subset of salt-loaded SHRSP was treated with nifedipine. Salt-loading in SHRSP increased blood pressure (ΔSBP 35 ± 5 mmHg, P<0.0001) and kidney injury markers such as kidney injury marker-1 (KIM-1; fold change, FC 3.4; P=0.003), neutrophil gelatinase-associated lipocalin (NGAL; FC, 2.0; P=0.012) and proteinuria. After salt-loading there was a reduction in urinary UMOD excretion in WKY and SHRSP by 26 and 55% respectively, compared with baseline. Nifedipine treatment reduced blood pressure (BP) in SHRSP, however, did not prevent salt-induced reduction in urinary UMOD excretion. In all experiments, changes in urinary UMOD excretion were dissociated from kidney UMOD protein and mRNA levels. Colocalization and ex-vivo studies showed that salt-loading increased intracellular UMOD retention in both WKY and SHRSP. Our study provides novel insights into the interplay among salt, UMOD, and BP. The role of UMOD as a cardiovascular risk marker deserves mechanistic reappraisal and further investigations based on our findings.

Proteomic discovery in sickle cell disease: Elevated neurogranin levels in children with sickle cell disease

PURPOSE

Sickle cell disease (SCD) is an inherited hemoglobinopathy that causes stroke and silent cerebral infarct (SCI). Our aim was to identify markers of brain injury in SCD.

EXPERIMENTAL DESIGN

Plasma proteomes were analyzed using a sequential separation approach of hemoglobin (Hb) and top abundant plasma protein depletion, followed by reverse phase separation of intact proteins, trypsin digestion, and tandem mass spectrometry. We compared plasma proteomes of children with SCD with and without SCI in the Silent Cerebral Infarct Multi-Center Clinical Trial (SIT Trial) to age-matched, healthy non-SCD controls.

RESULTS

From the SCD group, 1172 proteins were identified. Twenty-five percent (289/1172) were solely in the SCI group. Twenty-five proteins with enriched expression in the human brain were identified in the SCD group. Neurogranin (NRGN) was the most abundant brain-enriched protein in plasma of children with SCD. Using a NRGN sandwich immunoassay and SIT Trial samples, median NRGN levels were higher at study entry in children with SCD (0.28 ng/mL, N = 100) compared to control participants (0.12 ng/mL, N = 25, p < 0.0004).

CONCLUSIONS AND CLINICAL RELEVANCE

NRGN levels are elevated in children with SCD. NRGN and other brain-enriched plasma proteins identified in plasma of children with SCD may provide biochemical evidence of neurological injury.

Proteome Analysis of Urinary Biomarkers in Acute Hypercoagulable State Rat Model

Thrombotic diseases are usually preceded by a hypercoagulable state in the body. This study aimed to screen potential urinary biomarkers for hypercoagulable state based on proteome analysis. Wistar rats were administered with the hemostatic agent etamsylate to establish hypercoagulable state. Urine samples were collected for proteome analysis. We found 20 proteins with levels more than 1.5-fold in difference between control rats and model rats. We searched human homologs of 20 rat proteins and identified 13 human proteins. Of the 13 human homologous proteins, nine were members of human core urinary proteome. Human homologous proteins of differential proteins were highly expressed in 31 human tissues, especially in the kidneys followed by digestive system and reproductive system. Surprisingly, we did not identify known coagulation factors as differential proteins in the urine of model rats. Hypercoagulable state of the body may not involve direct changes in coagulation factors but causes the changes upstream of the coagulation cascade system. Common differential urinary proteins between different hypercoagulable states suggest some common pathways in the formation of hypercoagulable states and may serve as potential biomarkers for the prevention and treatment of thrombotic diseases.

Astrocytic nutritional dysfunction associated with hypoxia-induced neuronal vulnerability in stroke-prone spontaneously hypertensive rats

Stroke-prone spontaneously hypertensive rats (SHRSP) is a valuable animal model to investigate human strokes. SHRSP Izumo strain (Izm) neurons are highly sensitive to blood supply changes. Furthermore, SHRSP/Izm astrocytes show various abnormalities upon hypoxic stimulation compared to control Wistar Kyoto (WKY/Izm) rats. This study aimed to describe stroke-related characteristics of SHRSP/Izm-derived neurons and astrocytes. In addition, we discuss the role of astrocytes in the development of stroke in SHRSP/Izm model. In SHRSP/Izm, neuronal death is induced upon reoxygenation after hypoxia. Furthermore, it was shown that SHRSP/Izm astrocytes show significantly reduced lactate production and supply ability to nerve cells when subjected to hypoxic stimulation. In particular, decreased lactate production and monocarboxylic acid transporter (MCT) expression in SHRSP/Izm astrocytes are factors that induce neuronal cell death. Remarkable differences in glial cell line-derived neurotrophic factor (GDNF) expression and L-serine production were also observed in SHRSP/Izm-derived astrocytes compared to WKY/Izm. Reduced production of both GDNF and L-serine contributes to diminished neuronal survival. The differences between SHRSP/Izm and WKY/Izm astrocyte cellular properties may contribute to compromised neuronal nutrition and induction of neuronal death. These properties are likely to be the factors that enhance stroke in SHRSP/Izm.

Therapeutic targets of oxidative/nitrosative stress and neuroinflammation in ischemic stroke: Applications for natural product efficacy with omics and systemic biology

Oxidative/nitrosative stress and neuroinflammation are critical pathological processes in cerebral ischemia-reperfusion injury, and their intimate interactions mediate neuronal damage, blood-brain barrier (BBB) damage and hemorrhagic transformation (HT) during ischemic stroke. We review current progress towards understanding the interactions of oxidative/nitrosative stress and inflammatory responses in ischemic brain injury. The interactions between reactive oxygen species (ROS)/reactive nitrogen species (RNS) and innate immune receptors such as TLR2/4, NOD-like receptor, RAGE, and scavenger receptors are crucial pathological mechanisms that amplify brain damage during cerebral ischemic injury. Furthermore, we review the current progress of omics and systematic biology approaches for studying complex network regulations related to oxidative/nitrosative stress and inflammation in the pathology of ischemic stroke. Targeting oxidative/nitrosative stress and neuroinflammation could be a promising therapeutic strategy for ischemic stroke treatment. We then review recent advances in discovering compounds from medicinal herbs with the bioactivities of simultaneously regulating oxidative/nitrosative stress and pro-inflammatory molecules for minimizing ischemic brain injury. These compounds include sesamin, baicalin, salvianolic acid A, 6-paradol, silymarin, apocynin, 3H-1,2-Dithiole-3-thione, (-)-epicatechin, rutin, Dl-3-N-butylphthalide, and naringin. We finally summarize recent developments of the omics and systematic biology approaches for exploring the molecular mechanisms and active compounds of Traditional Chinese Medicine (TCM) formulae with the properties of antioxidant and anti-inflammation for neuroprotection. The comprehensive omics and systematic biology approaches provide powerful tools for exploring therapeutic principles of TCM formulae and developing precision medicine for stroke treatment.

Integrated analysis of the proteome and transcriptome in a MCAO mouse model revealed the molecular landscape during stroke progression

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DIA proteomics was applied to MCAO mice detection for the first time.

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Proteomics and bioinformatics revealed relationship between stroke process and immunity, especially inflammation.

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C3, Apoa4 and S100a9 were highlighted as a marker or drug targets for stroke.

Strokes usually results in long-term disability and death, and they occur worldwide. Recently, increased research on both on the physiopathological mechanisms and the transcriptome during stroke progression, have highlighted the relationship between stroke progression and immunity, with a special focus on inflammation. Here, we applied proteome analysis to a middle carotid artery occlusion (MCAO) mouse model at 0 h, 6 h, 12 h and 24 h, in which proteome profiling was performed with 23 samples, and 41 differentially expressed proteins (DEPs) were identified. Bioinformatics studies on our data revealed the importance of the immune response and particularly identified the inflammatory response, cytokine- cytokine receptor interactions, the innate immune response and reactive oxygen species (ROS) during stroke progression. In addition, we compared our data with multiple gene expression omnibus (GEO) datasets with and without a time series, in which similar pathways were identified, and three proteins, C3, Apoa4 and S100a9, were highlighted as markers or drug targets for stroke; these three proteins were significantly upregulated in the MCAO model, both in our proteomic data and in the GEO database.

Impact of angiotensin-converting enzyme inhibition on platelet tissue factor expression in stroke-prone rats

Supplemental Digital Content is available in the text

Objective:

Hypertension is a well known risk factor for thrombotic events such as myocardial infarction and stroke. Platelets express tissue factor (TF), the key activator of blood coagulation and thrombus formation. The number of TF-positive platelets increases in pathological conditions characterized by thrombotic complications but whether this occurs in hypertension is unknown. Here we investigated whether platelet TF expression is increased in a hypertensive status through a mechanism acting on megakaryocytes; the phenomenon could be modulated by antihypertensive drug as captopril; angiotensin (AngII) influences platelet TF expression.

Methods:

Spontaneously hypertensive stroke prone (SHRSP) rats received standard diet (StD) or a Japanese high-salt permissive diet (JpD). After 3 weeks, JpD animals were randomized to receive captopril or vehicle. Normotensive Wistar Kyoto (WKY) rats were used as controls. Cell-associated TF expression and activity were analyzed by flow cytometry and calibrated automated thrombogram, respectively.

Results:

Hypertensive StD-SHRSP showed an increased number of TF-positive platelets compared with normotensive WKY. After JpD administration, SHRSP developed severe hypertension and renal damage; the number of TF-positive megakaryocytes significantly increased compared with StD-SHRSP resulting in a higher number of TF-positive platelets with a faster kinetic of thrombin generation. These effects were reverted by captopril. Ex-vivo stimulation of platelets, isolated from normotensive WKY and from healthy individuals, with AngII induced a concentration-dependent increase of surface-associated TF expression.

Conclusion:

The current study shows for the first time that in hypertension the number of TF-positive megakaryocytes increases thus releasing in the circulation more platelets carrying a functionally active TF. AngII stimulates platelets to express TF.

Fenofibrate attenuates cardiac and renal alterations in young salt-loaded spontaneously hypertensive stroke-prone rats through mitochondrial protection

OBJECTIVES

The simultaneous presence of cardiac and renal diseases is a pathological condition that leads to increased morbidity and mortality. Several lines of evidence have suggested that lipid dysmetabolism and mitochondrial dysfunction are pathways involved in the pathological processes affecting the heart and kidney. In the salt-loaded spontaneously hypertensive stroke-prone rat (SHRSP), a model of cardiac hypertrophy and nephropathy that shows mitochondrial alterations in the myocardium, we evaluated the cardiorenal effects of fenofibrate, a peroxisome proliferator-activated receptor alpha (PPARα) agonist that acts by modulating mitochondrial and peroxisomal fatty acid oxidation.

METHODS

Male SHRSPs aged 6-7 weeks were divided in three groups: standard diet (n = 6), Japanese diet with vehicle (n = 6), and Japanese diet with fenofibrate 150 mg/kg/day (n = 6) for 5 weeks. Cardiac and renal functions were assessed in vivo by MRI, ultrasonography, and biochemical assays. Mitochondria were investigated by transmission electron microscopy, succinate dehydrogenase (SDH) activity, and gene expression analysis.

RESULTS

Fenofibrate attenuated cardiac hypertrophy, as evidenced by histological and MRI analyses, and protected the kidneys, preventing morphological alterations, changes in arterial blood flow velocity, and increases in 24-h proteinuria. Cardiorenal inflammation, oxidative stress, and cellular senescence were also inhibited by fenofibrate. In salt-loaded SHRSPs, we observed severe morphological mitochondrial alterations, reduced SDH activity, and down-regulation of genes regulating mitochondrial fatty-acid oxidation (i.e. PPARα, SIRT3, and Acadm). These changes were counteracted by fenofibrate. In vitro, a direct protective effect of fenofibrate on mitochondrial membrane potential was observed in albumin-stimulated NRK-52E renal tubular epithelial cells.

CONCLUSION

The results suggest that the cardiorenal protective effects of fenofibrate in young male salt-loaded SHRSPs are explained by its capacity to preserve mitochondrial function.

Hypoxia promotes tau hyperphosphorylation with associated neuropathology in vascular dysfunction

BACKGROUND

Hypertension-induced microvascular brain injury is a major vascular contributor to cognitive impairment and dementia. We hypothesized that chronic hypoxia promotes the hyperphosphorylation of tau and cell death in an accelerated spontaneously hypertensive stroke prone rat model of vascular cognitive impairment.

METHODS

Hypertensive male rats (n = 13) were fed a high salt, low protein Japanese permissive diet and were compared to Wistar Kyoto control rats (n = 5).

RESULTS

Using electron paramagnetic resonance oximetry to measure in vivo tissue oxygen levels and magnetic resonance imaging to assess structural brain damage, we found compromised gray (dorsolateral cortex: p = .018) and white matter (corpus callosum: p = .016; external capsule: p = .049) structural integrity, reduced cerebral blood flow (dorsolateral cortex: p = .005; hippocampus: p < .001; corpus callosum: p = .001; external capsule: p < .001) and a significant drop in cortical oxygen levels (p < .05). Consistently, we found reduced oxygen carrying neuronal neuroglobin (p = .008), suggestive of chronic cerebral hypoperfusion in high salt-fed rats. We also observed a corresponding increase in free radicals (NADPH oxidase: p = .013), p-Tau (pThr231) in dorsolateral cortex (p = .011) and hippocampus (p = .003), active interleukin-1β (p < .001) and neurodegeneration (dorsolateral cortex: p = .043, hippocampus: p = .044). Human patients with subcortical ischemic vascular disease, a type of vascular dementia (n = 38; mean age = 68; male/female ratio = 23/15) showed reduced hippocampal volumes and cortical shrinking (p < .05) consistent with the neuronal cell death observed in our hypertensive rat model as compared to healthy controls (n = 47; mean age = 63; male/female ratio = 18/29).

CONCLUSIONS

Our data support an association between hypertension-induced vascular dysfunction and the sporadic occurrence of phosphorylated tau and cell death in the rat model, correlating with patient brain atrophy, which is relevant to vascular disease.

Prospects of modeling poststroke epileptogenesis

This Review describes the current status of poststroke epilepsy (PSE) with an emphasis on poststroke epileptogenesis modeling for testing new therapeutic agents. Stroke is a leading cause of epilepsy in an aging population. Late-onset "epileptic" seizures have been reported in up to 30% cases after stroke. Nevertheless, the overall prevalence of PSE is 2-4%. Rodent models of stroke have contributed to our understanding of the relationship between seizures and the underlying ischemic damage to neurons. To understand whether acutely generated stroke events lead to a chronic phenotype more closely resembling PSE with recurrent seizures, a limited variety of approaches emerged in early 2000s. These limited methods of causing an occlusion in mice and rats show different infarct size and neurological deficits. The most often employed procedure for inducing focal ischemia is the middle cerebral artery occlusion. This mimics the pathophysiology seen in humans in terms of extent of damage to cortex and striatum. Photothrombosis and endothelin-1 models can similarly evoke episodes of ischemic stroke. These models are well suited to studying mechanisms and biomarkers of epileptogenesis or optimizing novel drug discoveries. However, modeling of PSE is tedious, is highly variable, and lacks validity; therefore, it is not widely implemented in epilepsy research. Moreover, the relevance of ischemic models to specific forms of human stroke remains unclear. Stroke modeling in young male rodents lacks clinical relevance to elderly populations and especially to women, likely as a result of sex differences. Nevertheless, because of the neuronal damage and epileptogenic insult that these models trigger, they are helpful tools in studying acquired epilepsy and prophylactic drug therapy. © 2016 Wiley Periodicals, Inc.

Mitochondrial Dysfunction Contributes to Hypertensive Target Organ Damage: Lessons from an Animal Model of Human Disease

Mechanisms underlying hypertensive target organ damage (TOD) are not completely understood. The pathophysiological role of mitochondrial oxidative stress, resulting from mitochondrial dysfunction, in development of TOD is unclear. The stroke-prone spontaneously hypertensive rat (SHRSP) is a suitable model of human hypertension and of its vascular consequences. Pathogenesis of TOD in SHRSP is multifactorial, being determined by high blood pressure levels, high salt/low potassium diet, and genetic factors. Accumulating evidence points to a key role of mitochondrial dysfunction in increased susceptibility to TOD development of SHRSP. Mitochondrial abnormalities were described in both heart and brain of SHRSP. Pharmacological compounds able to protect mitochondrial function exerted a significant protective effect on TOD development, independently of blood pressure levels. Through our research efforts, we discovered that two genes encoding mitochondrial proteins, one (Ndufc2) involved in OXPHOS complex I assembly and activity and the second one (UCP2) involved in clearance of mitochondrial ROS, are responsible, when dysregulated, for vascular damage in SHRSP. The suitability of SHRSP as a model of human disease represents a promising background for future translation of the experimental findings to human hypertension. Novel therapeutic strategies toward mitochondrial molecular targets may become a valuable tool for prevention and treatment of TOD in human hypertension.

Proteomics in stroke research: potentials of the nascent proteomics

Among omics, the proteomics assumes a unique role in that it offers the effectors or actuators of a biological condition. This brief review attempts to summarize the development in a relatively new but important subdiscipline of proteomics, the so-called nascent proteomics, and its potential applications in stroke research. First, we will discuss a few examples of proteomics-led discoveries in stroke research, and challenges or unmet demands when using commonly practiced proteomics approaches. Then we will introduce nascent proteomics and its studying tools, followed by discussions on its potentials in stroke research.

Protective effects of Brassica oleracea sprouts extract toward renal damage in high-salt-fed SHRSP: role of AMPK/PPARα/UCP2 axis

OBJECTIVES

Renal damage precedes occurrence of stroke in high-sodium/low-potassium-fed stroke-prone spontaneously hypertensive rat (SHRSP). We previously reported a marked suppression of uncoupling protein-2 (UCP2) upon high-salt Japanese-style diet in SHRSP kidneys. Vegetable compounds are known to exert protective effects in cardiovascular diseases. We aimed at evaluating the impact of Brassica oleracea sprouts juice toward renal damage in Japanese diet-fed SHRSP and exploring the role of 5'-adenosine monophosphate-activated protein kinase (AMPK)/NAD-dependent deacetylase sirtuin-1 (SIRT1)/peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α)/peroxisome proliferator-activated receptor-α (PPARα)/UCP2 axis.

METHODS

SHRSP received Japanese diet for 4 weeks. A group of SHRSP received Japanese diet and B. oleracea. A third group received Japanese diet, B. oleracea, and PPARα inhibitor (GW6471). A group of SHRSP fed with regular diet served as control.

RESULTS

Japanese diet induced marked increases of oxidative stress, inflammation, and proteinuria, along with glomerular and tubular damage, as compared with regular diet. A significant suppression of AMPK/UCP2 pathway was observed. Despite Japanese diet feeding, concomitant administration of B. oleracea prevented oxidative stress accumulation, inflammation, renal damage, and proteinuria. All components of the UCP2 regulatory pathway were significantly increased by B. oleracea. Superoxide dismutase 2 and phosphoendothelial nitric oxide synthase were also stimulated. Addition of PPARα inhibitor to B. oleracea and Japanese diet significantly reduced the B. oleracea beneficial effects. SBP levels were comparable among the different groups of rats.In vitro, UCP2 inhibition by genipin offset the antioxidant effect of B. oleracea in renal mesangial and proximal tubular cells.

CONCLUSION

B. oleracea administration prevented renal damage in salt-loaded SHRSP, independently from SBP, with parallel stimulation of AMPK/SIRT1/PGC1α/PPARα/UCP2 axis. Stimulation of the latter mechanism may provide relevant renal protective effect and play a therapeutic role in target organ damage progression in hypertension.

Urinary Biomarkers of Brain Diseases

Biomarkers are the measurable changes associated with a physiological or pathophysiological process. Unlike blood, urine is not subject to homeostatic mechanisms. Therefore, greater fluctuations could occur in urine than in blood, better reflecting the changes in human body. The roadmap of urine biomarker era was proposed. Although urine analysis has been attempted for clinical diagnosis, and urine has been monitored during the progression of many diseases, particularly urinary system diseases, whether urine can reflect brain disease status remains uncertain. As some biomarkers of brain diseases can be detected in the body fluids such as cerebrospinal fluid and blood, there is a possibility that urine also contain biomarkers of brain diseases. This review summarizes the clues of brain diseases reflected in the urine proteome and metabolome.

Altered iron homeostasis in an animal model of hypertensive nephropathy: stroke-prone rats

BACKGROUND AND AIM

Iron is the most abundant metal in mammalian cells, and plays a pivotal role in many metabolic processes. Dysregulated iron homeostasis is involved in the cause of a number of pathological processes including renal diseases.

METHODS AND RESULTS

Longitudinal MRI scans of salt-loaded spontaneously hypertensive stroke-prone rats (SHRSP), an animal model that spontaneously develops hypertensive nephropathy, showed a decrease in renal and hepatic T2 SI (a sign of iron accumulation) of, respectively, 42.3 ± 2.5% (P < 0.01) and 60.4 ± 15.1% (P < 0.01) in comparison with SHRSP fed a standard diet. This was accompanied by the development of renal inflammation and oxidative stress (as evaluated by immunohistochemical and proteomic analyses), mitochondrial dysfunction, massive proteinuria and sustained intravascular hemolysis with the subsequent depletion of plasma haptoglobin, which was responsible for the renal uptake of hemoglobin and iron accumulation. In order to investigate the role of iron in these pathological processes, we subcutaneously treated the salt-loaded rats with the iron chelator deferoxamine (200 mg/kg per day). The pharmacological treatment prevented iron tissue accumulation, as indicated by the increase in renal and hepatic T2 SI of, respectively, 120.0 ± 10.1% (P < 0.01) and 73.9 ± 4.4% (P < 0.01) in comparison with salt-loaded rats treated with vehicle alone. Deferoxamine also preserved renal morphology and function, the renal infiltration of ED-1-positive macrophages/monocytes, and the expression of MCP-1 and TGF-β mRNA, reduced the level of reactive oxygen species, and improved the activity of mitochondrial cytochrome c oxidase.

CONCLUSION

These findings suggest that iron dysmetabolism is involved in the development of hypertensive nephropathy in SHRSP.

Gene expression profiling in stroke: relevance of blood-brain interaction

Biomarker profiling is utilized to identify diagnostic and prognostic candidates for stroke. Clinical and preclinical biomarker data suggest altered circulating immune responses may illuminate the mechanisms of stroke recovery. However, the relationship between peripheral blood biomarker profile(s) and brain profiles following stroke remains elusive. Data show that neutrophil lymphocyte ratio (NLR) predicts stroke outcome. Neutrophils release Arginase 1 (ARG1) resulting in T lymphocyte suppression in peripheral blood. Interestingly, the cellular response to stroke may have implications for known biomarker profiles. Conversely, preclinical evidence suggests that upregulation of ARG1 in microglia is a marker of M2 macrophages and may influence neuroprotection. Comparing clinical and preclinical studies creates opportunities to explore the molecular mechanisms of blood and brain biomarker interactions in stroke.

Differential gene expression in multiple neurological, inflammatory and connective tissue pathways in a spontaneous model of human small vessel stroke

AIMS

Cerebral small vessel disease (SVD) causes a fifth of all strokes plus diffuse brain damage leading to cognitive decline, physical disabilities and dementia. The aetiology and pathogenesis of SVD are unknown, but largely attributed to hypertension or microatheroma.

METHODS

We used the spontaneously hypertensive stroke-prone rat (SHRSP), the closest spontaneous experimental model of human SVD, and age-matched control rats kept under identical, non-salt-loaded conditions, to perform a blinded analysis of mRNA microarray, qRT-PCR and pathway analysis in two brain regions (frontal and mid-coronal) commonly affected by SVD in the SHRSP at age five, 16 and 21 weeks.

RESULTS

We found gene expression abnormalities, with fold changes ranging from 2.5 to 59 for the 10 most differentially expressed genes, related to endothelial tight junctions (reduced), nitric oxide bioavailability (reduced), myelination (impaired), glial and microglial activity (increased), matrix proteins (impaired), vascular reactivity (impaired) and albumin (reduced), consistent with protein expression defects in the same rats. All were present at age 5 weeks thus predating blood pressure elevation. 'Neurological' and 'inflammatory' pathways were more affected than 'vascular' functional pathways.

CONCLUSIONS

This set of defects, although individually modest, when acting in combination could explain the SHRSP's susceptibility to microvascular and brain injury, compared with control rats. Similar combined, individually modest, but multiple neurovascular unit defects, could explain susceptibility to spontaneous human SVD.

Systemic inflammation as a therapeutic target in acute ischemic stroke

Acute systemic inflammatory reaction superimposed on chronic low-grade inflammation accompanies acute ischemic stroke. Elevated blood levels of systemic inflammatory markers such as IL-6 or C-reactive protein are associated with an unfavorable functional outcome and increased mortality after stroke. Animal studies have demonstrated a causal relationship between systemic inflammation and ischemic brain damage. The mechanisms linking systemic inflammation with poor outcome include increased neutrophil infiltration of cerebral cortex, disruption of the blood-brain barrier, impaired tissue reperfusion, increased platelet activation and microvascular coagulation and complement-dependent brain injury. Non-selective (e.g., by statins) or selective (e.g., by inhibition of IL-6) attenuation of systemic inflammation, enhancement of systemic anti-inflammatory response (e.g., by infusion of IL-1 receptor antagonist), prevention of infections that exacerbate systemic inflammation or inhibition of neuronal pathways triggering inflammatory reaction are potential therapeutic targets in stroke patients. This review discusses the relationship between systemic inflammation, cerebral ischemia and prognosis in the context of therapeutic strategies.

Vascular and parenchymal lesions along with enhanced neurogenesis characterize the brain of asymptomatic stroke-prone spontaneous hypertensive rats

BACKGROUND AND OBJECTIVES

Spontaneously hypertensive stroke-prone rats (SHRSPs) develop hypertension, cerebrovascular abnormalities and a stroke phenotype in association with higher levels of proteinuria. Here, we focus on cerebral abnormalities preceding lesions detectable by MRI.

METHODS

Longitudinal assessment of brain histology was performed in salt-loaded male SHRSPs (n = 26) and Wistar-Kyoto (WKY) normotensive control animals (n = 27). Groups of rats were sacrificed at different time points: Time 0, before the salt diet administration; Time 1, when proteinuria achieved 40 mg/day; Time 2, when proteinuria exceeded 100 mg/day.

RESULTS

At Time 0, no brain lesions were observed. At Time 1, changes of the cortical penetrating arteries, vasogenic oedema, lacunae and focal cell loss appeared in SHRSPs and worsened at Time 2, although no lesions were yet detected by MRI. Staining for proliferation markers revealed a significant boost of cellular mitosis in the subventricular zone (SVZ) of SHRSPs. Moreover, we observed higher immunopositivity for nestin, glial fibrillary acidic protein and doublecortin (markers for neural stem cells, astrocytes and immature neurons, respectively). At Time 2, apoptotic caspase-3 as well as 4-hydroxynonenal-positive neurons were associated to decreased nestin and doublecortin staining. High expression levels of glial fibrillary acidic protein were maintained in the SVZ. No comparative alterations and SVZ activation were recorded in WKYs.

CONCLUSION

Appearance of vascular changes in SHRSPs, before any MRI-detectable brain lesion, is coupled to active neural proliferation in the SVZ. With disease progression, only newborn astrocytes can survive, likely because of the neurotoxicity triggered by brain oedema and oxidative stress.

Application of proteomics to cerebrovascular disease

While neurovascular diseases such as ischemic and hemorrhagic stroke are the leading causes of disability in the world, the repertoire of therapeutic interventions has remained remarkably limited. There is a dire need to develop new diagnostic, prognostic, and therapeutic options. The study of proteomics is particularly enticing for cerebrovascular diseases such as stroke, which most likely involve multiple gene interactions resulting in a wide range of clinical phenotypes. Currently, rapidly progressing neuroproteomic techniques have been employed in clinical and translational research to help identify biologically relevant pathways, to understand cerebrovascular pathophysiology, and to develop novel therapeutics and diagnostics. Future integration of proteomic with genomic, transcriptomic, and metabolomic studies will add new perspectives to better understand the complexities of neurovascular injury. Here, we review cerebrovascular proteomics research in both preclinical (animal, cell culture) and clinical (blood, urine, cerebrospinal fluid, microdialyates, tissue) studies. We will also discuss the rewards, challenges, and future directions for the application of proteomics technology to the study of various disease phenotypes. To capture the dynamic range of cerebrovascular injury and repair with a translational targeted and discovery approach, we emphasize the importance of complementing innovative proteomic technology with existing molecular biology models in preclinical studies, and the need to advance pharmacoproteomics to directly probe clinical physiology and gauge therapeutic efficacy at the bedside.

Proteomics-based investigations of animal models of disease

Cells contain a large yet, constant genome, which contains all the coding information necessary to sustain cellular physiology. However, proteins are the end products of genes, and hence dictate the phenotype of cells and tissues. Therefore, proteomics can provide key information for the elucidation of physiological and pathophysiological mechanisms by identifying the protein profile from cells and tissues. The relatively novel techniques used for the study of proteomics thus have the potential to improve diagnostic, prognostic, as well as therapeutic avenues. In this review, we first discuss the benefits of animal models over the use of human samples for the proteomic analysis of human disease. Next, we aim to demonstrate the potential of proteomics in the elucidation of disease mechanisms that may not be possible by other conventional technologies. Following this, we describe the use of proteomics for the analysis of PTM and protein interactions in animal models and their relevance to the study of human disease. Finally, we discuss the development of clinical biomarkers for the early diagnosis of disease via proteomic analysis of animal models. We also discuss the development of standard proteomes and relate how this data will benefit future proteomic research. A comprehensive review of all animal models used in conjunction with proteomics is beyond the scope of this manuscript. Therefore, we aimed to cover a large breadth of topics, which together, demonstrate the potential of proteomics as a powerful tool in biomedical research.

Transthyretin: roles in the nervous system beyond thyroxine and retinol transport

Transthyretin (TTR) is a plasma- and cerebrospinal fluid-circulating protein. Besides the primordially attributed systemic role as a transporter molecule of thyroxine (T₄) and retinol (through the binding to retinol-binding protein [RBP]), TTR has been recognized as a protein with important functions in several aspects of the nervous system physiology. TTR has been shown to play an important role in behavior, cognition, amidated neuropeptide processing and nerve regeneration. Furthermore, it has been proposed that TTR is neuroprotective in Alzheimer's disease and cerebral ischemia. Mutations in TTR are a well-known cause of familial amyloidotic polyneuropathy, an autosomal dominant neurodegenerative disorder characterized by systemic deposition of TTR amyloid fibrils, particularly in the peripheral nervous system. The purpose of this review is to highlight the roles of TTR in the nervous system, beyond its systemic role as a transporter molecule of T₄ and RBP-retinol.

Is the spontaneously hypertensive stroke prone rat a pertinent model of sub cortical ischemic stroke? A systematic review

The spontaneously hypertensive stroke prone rat is best known as an inducible model of large artery stroke. Spontaneous strokes and stroke propensity in the spontaneously hypertensive stroke prone rat are less well characterized; however, could be relevant to human lacunar stroke. We systematically reviewed the literature to assess the brain tissue and small vessel pathology underlying the spontaneous strokes of the spontaneously hypertensive stroke prone rat. We searched systematically three online databases from 1970 to May 2010; excluded duplicates, reviews, and articles describing the consequences of induced middle cerebral artery occlusion or noncerebral pathology; and recorded data describing brain region and the vessels examined, number of animals, age, dietary salt intake, vascular and tissue abnormalities. Among 102 relevant studies, animals sacrificed after developing stroke-like symptoms displayed arteriolar wall thickening, subcortical lesions, enlarged perivascular spaces and cortical infarcts and hemorrhages. Histopathology, proteomics and imaging studies suggested that the changes not due simply to hypertension. There may be susceptibility to endothelial permeability increase that precedes arteriolar wall thickening, degeneration and perivascular tissue changes; systemic inflammation may also precede cerebrovascular changes. There were very few data on venules or tissue changes before hypertension. The spontaneously hypertensive stroke prone rat shows similar features to human lacunar stroke and may be a good spontaneous model of this complex human disorder. Further studies should focus on structural changes at early ages and genetics to identify factors that predispose to vascular and brain damage.

Combined age- and trauma-related proteomic changes in rat neocortex: a basis for brain vulnerability

This proteomic study investigates the widely observed clinical phenomenon, that after comparable brain injuries, geriatric patients fare worse and recover less cognitive and neurologic function than younger victims. Utilizing a rat traumatic brain injury model, sham surgery or a neocortical contusion was induced in 3 age groups. Geriatric (21 months) rats performed worse on behavioral measures than young adults (12-16 weeks) and juveniles (5-6 weeks). Motor coordination and certain cognitive deficits showed age-dependence both before and after injury. Brain proteins were analyzed using silver-stained two-dimensional electrophoresis gels. Spot volume changes (>2-fold change, p<0.01) were identified between age and injury groups using computer-assisted densitometry. Sequences were determined by mass spectrometry of tryptic peptides. The 19 spots identified represented 13 different genes that fell into 4 general age- and injury-dependent expression patterns. Fifteen isoforms changed differentially with respect to both age and injury (p<0.05). Further investigations into the nature and function of these isoforms may yield insights into the vulnerability of older patients and resilience of younger patients in recovery after brain injuries.

Terutroban, a thromboxane/prostaglandin endoperoxide receptor antagonist, prevents hypertensive vascular hypertrophy and fibrosis

Thromboxane A2 and other eicosanoids such as isoprostanes contribute to vascular proliferation and atherosclerosis by binding to the thromboxane/prostaglandin endoperoxide receptors. The effects of terutroban, a thromboxane/prostaglandin endoperoxide receptor antagonist, on aorta remodeling were evaluated in spontaneously hypertensive stroke-prone rats (SHRSPs), a model of severe hypertension, endothelial dysfunction, vascular inflammation, and cerebrovascular diseases. Male SHRSPs were allocated to three groups receiving a standard diet ( n = 5) or a high-sodium permissive diet plus vehicle ( n = 6) or plus terutroban (30 mg·kg−1·day−1; n = 6). After 6 wk of dietary treatment, all of the animals were injected with bromodeoxyuridine and simultaneously euthanized for aorta collection. The aortic media thickness-to-lumen ratio significantly ( P < 0.0001) increased in the salt-loaded rats compared with the rats fed a standard diet, whereas terutroban treatment completely prevented media thickening ( P < 0.001). When compared with vehicle, terutroban was also effective in preventing cell proliferation in the media, as indicated by the reduced number of bromodeoxyuridine-positive ( P < 0.0001) and proliferating cell nuclear antigen-positive cells ( P < 0.0001). Severe fibrosis characterized by a significant accumulation of collagen and fibronectin in the vascular wall was observed in the vehicle-treated rats ( P < 0.01) but was completely prevented by terutroban ( P < 0.001). The latter also inhibited heat shock protein-47 ( P < 0.01) and TGF-1β expression ( P < 0.001), which were significantly increased by the high-salt diet. In conclusion, terutroban prevents the development of aorta hyperplasia and has beneficial effects on fibrotic processes by affecting TGF-β and heat shock protein-47 expression in SHRSPs. These findings provide mechanistic data supporting the beneficial effects of terutroban in preventing or retarding atherogenesis.

CSF transthyretin neuroprotection in a mouse model of brain ischemia

Brain injury caused by ischemia is a major cause of human mortality and physical/cognitive disability worldwide. Experimentally, brain ischemia can be induced surgically by permanent middle cerebral artery occlusion. Using this model, we studied the influence of transthyretin in ischemic stroke. Transthyretin (TTR) is normally responsible for the transport of thyroid hormones and retinol in the blood and CSF. We found that TTR null mice (TTR(-/-) ) did not show significant differences in cortical infarction 24 h after permanent middle cerebral artery occlusion compared with TTR(+/+) control littermates. However, TTR null mice, heterozygous for the heat-shock transcription factor 1 (TTR(-/-) HSF1(+/-) mice), which compromised the stress response, showed a significant increase in cortical infarction, cerebral edema and the microglial-leukocyte response compared with TTR(+/+) HSF1(+/-) mice. Unexpectedly, we observed novel TTR distribution throughout the infarct, localized to disintegrated β-tubulin III(+) neurons and cell debris. Specific elimination of TTR synthesis in the liver by RNAi had no effect on TTR distribution in the infarct, indicating that the observed TTR infiltration derived from CSF and not from the serum. This finding is corroborated by results from 'in situ' hybridization and real time PCR that excluded the presence of transthyretin mRNA in the infarct and peri-infarct areas. Our data suggest that in conditions of a compromised heat-shock response, CSF TTR contributes to control neuronal cell death, edema and inflammation, thereby influencing the survival of endangered neurons in cerebral ischemia.

Hypertension-induced vascular remodeling contributes to reduced cerebral perfusion and the development of spontaneous stroke in aged SHRSP rats

Stroke in spontaneously-hypertensive, stroke-prone (SHRSP) rats is of particular interest because the pathogenesis is believed to be similar to that in the clinical setting. In this study, we employed multi-modal MRI-ASL, DWI, T(2), GRE, T(1) (pre/post contrast)-to investigate the natural history of spontaneous cerebral infarction and the specific role of cerebral perfusion in disease development. Twelve female SHRSP rats (age: approximately 1 year) were imaged within 1 to 3 days of symptom onset. The distribution of ischemic lesions was the following: 28.1% visual, 21.9% striatal, 18.8% motorsensory, 12.5% thalamic, 12.5% auditory, 3.1% frontal/prelimbic, and 3.1% multiple areas. Ischemic lesions had significantly reduced blood flow in comparison with healthy tissue. Ischemic lesions were characterized by hyperplastic, thrombosed, and compressed vessels. These findings suggest that ischemic lesion development is related to hypertension-induced vascular remodeling and persistent hypoperfusion. This model should be useful for studying the relationship between chronic hypertension and subsequent stroke, both in terms of primary and secondary prevention.

Stimulation of AT2 receptor exerts beneficial effects in stroke-prone rats: focus on renal damage

BACKGROUND AND AIM

Angiotensin II acts through two major receptors: AT1-R and AT2-R. It is known that the stimulation of AT1-R mediates vasoconstriction, cell proliferation and fibrosis, aldosterone release and inflammatory response but, although the stimulation of AT2-R is thought to promote vasodilation and anti-inflammatory effects, its real in-vivo functions are still unclear. The aim of this study was to investigate the effects of specific and selective AT2-R stimulation on the pathological events occurring in spontaneously hypertensive stroke-prone rats (SHRSPs).

METHODS AND RESULTS

SHRSPs who were fed a high-salt diet underwent long-term treatment with vehicle or compound 21 (C21), a nonpeptide selective AT2-R agonist, at doses of 0.75, 5 and 10 mg/kg per day. The vehicle-treated rats developed brain abnormalities detectable by magnetic resonance imaging after 42.5 +/- 7.5 days, and died 43 +/- 9.5 days after the start of the dietary treatment. The highest C21 dose delayed the occurrence of brain damage (P < 0.001 vs. vehicle-treated SHRSPs) and prolonged survival (P < 0.001) without affecting blood pressure. These beneficial effects of C21 were abolished by the administration of PD123319, an AT2-R antagonist. C21 treatment preserved renal structure by preventing inflammatory cell infiltration, collagen accumulation, and the neo-expression of vimentin; it also prevented the increased plasma renin activity and accumulation of urinary acute-phase proteins observed in the vehicle-treated rats.

CONCLUSION

Specific and selective AT2-R stimulation has beneficial effects on the pathological events occurring in SHRSPs. These data indicate a new avenue for the pharmacological treatment of diseases in which modulation of the renin-angiotensin system is required.

Lacunar stroke is associated with diffuse blood-brain barrier dysfunction

OBJECTIVE

Lacunar stroke is common (25% of ischemic strokes) and mostly because of an intrinsic cerebral microvascular disease of unknown cause. Although considered primarily to be an ischemic process, the vessel and tissue damage could also be explained by dysfunctional endothelium or blood-brain barrier (BBB) leak, not just ischemia. We tested for subtle generalized BBB leakiness in patients with lacunar stroke and control patients with cortical ischemic stroke.

METHODS

We recruited patients with lacunar and mild cortical stroke. We assessed BBB leak in gray matter, white matter, and cerebrospinal fluid, at least 1 month after stroke, using magnetic resonance imaging before and after intravenous gadolinium. We measured tissue enhancement for 30 minutes after intravenous gadolinium by two image analysis approaches (regions of interest and tissue segmentation). We compared the enhancement (leak) between lacunar and cortical patients, and associations with key variables, using general linear modeling.

RESULTS

We recruited 51 lacunar and 46 cortical stroke patients. Signal enhancement after gadolinium was higher in lacunar than cortical stroke patients in white matter (p < 0.001) and cerebrospinal fluid (p < 0.003) by both analysis methods, independent of other variables. Signal enhancement after gadolinium was also associated with increasing age and enlarged perivascular spaces, but these did not explain the lacunar-cortical difference.

INTERPRETATION

Patients with lacunar stroke have subtle, diffuse BBB dysfunction in white matter. Further studies are required to determine the relative contributions of BBB dysfunction and/or ischemia to the microvascular and brain abnormalities in lacunar stroke.

Blood–brain barrier: Ageing and microvascular disease – systematic review and meta-analysis

Cerebral "microvascular" disease occurs in lacunar stroke, leukoaraiosis, vascular dementia and Alzheimer's disease. It may arise from or contribute to insidious damage to the blood-brain barrier (BBB). We systematically reviewed the literature for evidence that BBB permeability is altered in patients with manifestations of cerebral microvascular disease. We found 31 BBB permeability studies (1953 individuals) of normal ageing or cerebral microvascular disease. In healthy humans, increasing age (10 comparisons, controls(C):subjects(S)=357:336) was associated with increased BBB permeability (standardised mean difference (S.M.D.) 1.21, 95% confidence interval (CI) 0.60, 1.81, p<0.01). BBB permeability was increased further in patients with either vascular or Alzheimer's dementia compared with age-matched controls (26 comparisons, C:S=510:547, S.M.D. 0.81, 99% CI 0.37, 1.26, p<0.01); in vascular compared with Alzheimer's dementia (10 comparisons, C:S=291:165, S.M.D. 0.71, 99% CI 0.12, 1.29, p<0.01); and with worsening leukoaraiosis (5 comparisons, C:S=122:88, S.M.D. 0.60, 99% CI 0.30, 0.89, p<0.01). BBB permeability increases with normal ageing and may be an important mechanism in the initiation or worsening of cerebral microvascular disease. Further studies on the role of BBB permeability are urgently needed.

Association between Histoplasma exposure and stroke

BACKGROUND AND PURPOSE

The rate of cerebrovascular events within the stroke belt, a geographic area defined in the Southeastern United States, exceeds that of the rest of the nation. Despite evaluation of multiple risk factors for this disparity, specific causes for the stroke belt have not been elucidated. More than 45 years ago, the US Public Health Service and US Navy cooperative skin-testing program (1958-1965) documented adolescent exposure to Histoplasma capsulatum. Our purpose was to evaluate the association between exposure to Histoplasma capsulatum and subsequent development of stroke.

METHODS

A cross-sectional study of stroke in a cohort of US Navy veterans was designed to assess our hypothesis. Medical records from 23,795 men who participated in the cooperative skin-testing program and who received medical care at Veterans Administration Hospitals and Clinics were reviewed. A logistic regression model was used to estimate the odds ratio of stroke while controlling for multiple covariates. Because of the large number of possible risk factors for stroke, propensity scores were used to reduce bias.

RESULTS

The adjusted odds ratio for stroke in veterans exposed to Histoplasma capsulatum during adolescence was 1.34 (95% confidence interval: 1.1-1.6; P = .0033). The increased risk was independent of traditional cerebrovascular event risk factors. Less frequent risk factors (atrial fibrillation, coronary heart disease, rheumatic heart disease, and prosthetic cardiac valvular replacement) were not controlled in this model.

CONCLUSION

Exposure to Histoplasma capsulatum during adolescence was associated with an increased risk of stroke.

S 35171 exerts protective effects in spontaneously hypertensive stroke-prone rats by preserving mitochondrial function

S 35171 is one of a family of compounds that have been designed to protect mitochondrial function. We tested the hypothesis that S 35171 exerts protective effects in spontaneously hypertensive stroke-prone rats (SHRSPs), an animal model developing spontaneous brain damage preceded by proteinuria and systemic inflammation revealed by the urinary accumulation of acute-phase proteins (APPs) originating in the liver. Male SHRSPs fed a permissive diet received vehicle or S 35171 (10 mg/kg/day) started simultaneously with a high-sodium diet (group A) or after the establishment of proteinuria (group B). The drug delayed urinary APPs accumulation and the appearance of magnetic resonance imaging (MRI)-monitored brain lesions (after 62+/-3 days in group A, and 51+/-2 days in controls, P<0.01). The delay was more pronounced in group B as 30% of the animals survived the entire 90-day experimental period without brain abnormality. Proteomic analysis showed no significant alteration in the expression pattern of brain mitochondrial proteins, but the liver mitochondrial levels of carbamoylphosphate synthase I (CPS-I), an enzyme involved in urea metabolism) and the antioxidant peroxiredoxin-3 spot were affected by hypertension and S 35171. Stress reduces CPS-I and induces the peroxiredoxin-3 spot, whereas S 35171 brought about normal CPS-I expression and a 12-fold higher level of the peroxiredoxin-3 spot. As both enzymes are involved in maintaining mitochondrial functions, their increased expression after S 35171 treatment may be responsible for delaying the pathological condition that leads to the development of brain damage in SHRSPs.

Do in vivo experimental models reflect human cerebral small vessel disease? A systematic review

Cerebral small vessel disease (SVD) is a major cause of stroke and dementia. Pathologically, three lesions are seen: small vessel arteriopathy, lacunar infarction, and diffuse white matter injury (leukoaraiosis). Appropriate experimental models would aid in understanding these pathologic states and also in preclinical testing of therapies. The objective was to perform a systematic review of animal models of SVD and determine whether these resemble four key clinicopathologic features: (1) small, discrete infarcts; (2) small vessel arteriopathy; (3) diffuse white matter damage; (4) cognitive impairment. Fifteen different models were included, under four categories: (1) embolic injuries (injected blood clot, photochemical, detergent-evoked); (2) hypoperfusion/ischaemic injury (bilateral common carotid occlusion/stenosis, striatal endothelin-1 injection, striatal mitotoxin 3-NPA); (3) hypertension-based injuries (surgical narrowing of the aorta, or genetic mutations, usually in the renin-angiotensin system); (4) blood vessel damage (injected proteases, endothelium-targeting viral infection, or genetic mutations affecting vessel walls). Chronic hypertensive models resembled most key features of SVD, and shared the major risk factors of hypertension and age with human SVD. The most-used model was the stroke-prone spontaneously hypertensive rat (SHR-SP). No model described all features of the human disease. The optimal choice of model depends on the aspect of pathophysiology being studied.