Current Neurovascular Research - Volume 5, Issue 2, 2008

Our work contributes to the understanding of the mechanisms of drug resistance in epilepsis. This study aimed to investigate i) the levels of expression of P-glycoprotein (P-gp), and multidrug resistance-associated proteins (MRP)1 and 2, ii) the activation of the pregnane X receptor (PXR) and the constitutive androstane receptor (CAR), and iii) the relationship between increased P-gp and MRPs expression and PXR and CAR activation, in immortalized rat brain microvascular endothelial cell lines, GPNT and RBE4, following treatment with the antiepileptic drugs (AEDs), topiramate, phenobarbital, carbamazepine, tiagabine, levetiracetam, and phenytoin, using Western blotting and immunocytochemistry methods. Carbamazepine, phenobarbital and phenytoin induced the highest levels of P-gp and MPRs expression that was associated with increased activation of PXR and CAR receptors as compared to levetiracetam, tiagabine and topiramate. We conclude that P-gp and MRPs are differently overexpressed in GPNT and RBE4 by various AEDs and both PXR and CAR are involved in the drug-resistant epilepsy induced by carbamazepine, phenobarbital and phenytoin.

Using Surface-Enhanced Laser Desorption / Ionization Time-of-Flight Mass Spectrometry (SELDI-TOF-MS), we aimed to detect differences in protein profile in serum samples of two lacunar stroke subtypes. SELDI-TOF-MS, followed by protein identification, was performed in samples of 8 first-ever lacunar stroke patients with MR imaging showing a single symptomatic lacunar lesion (type 1), and 8 with multiple additional “silent” lacunar lesions and extensive white matter lesions (type 2). A 16 kDa protein, identified as alpha-2-chain of haptoglobin (Hp), was found to be overrepresented in type 1 compared to type 2 (peak intensity 12.5 vs. 5.0; p=0.02). As a polymorphism with two alleles, Hp-1 and Hp-2, determines the presence of alpha-1 and/or alpha-2-chains in the Hp-molecule, Hp phenotypic analysis was performed. Hp-1 : Hp-2 allele frequency was 0.562 : 0.438 in type 1 and 0.812 : 0.188 in type 2 (population reference ∼0.4 : 0.6). We conclude that the overrepresentation of the alpha-2-chain in lacunar stroke type 1 compared to type 2 relates to a higher Hp-2 allele frequency in the former. Yet, compared to population reference, the phenotype distribution in both patient groups deviates towards a high Hp-1 allele frequency. Our findings suggest a role for the Hp gene in the etiology of cerebral small vessel disease. Larger studies are now needed to explore this new candidate gene.

Gastrin-releasing peptide (GRP) has been proposed as a major growth factor in brain tumors, and GRP receptor (GRPR) antagonists show antiproliferative effects in experimental gliomas. However, the underlying molecular events downstream of GRPR activation remain poorly understood. In the present study, we examined the role of the GRPR in regulating proliferation of glioma cells in vitro and its possible interaction with the phosphatidylinositol 3-kinase (PI3K) signaling pathway. Expression of GRPR mRNA and protein in C6, U-87MG, and U-373MG glioma cells was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. Proliferation of C6 and U-87MG, but not U-373MG cells was significantly inhibited by the GRPR antagonist RC-3095, whereas the GRPR agonist bombesin (BB) significantly enhanced proliferation of C6 cells. The BB-induced stimulatory effect on cell proliferation was prevented by either RC-3095 or the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. Our results provide the first evidence that the GRPR regulates proliferation of C6 glioma cells and suggest that PI3K is required for GRPR-mediated stimulation of glioma growth.

Silent brain infarction (SBI) is often detected on MR imaging, however the pathogenesis is still unclear. We aimed to investigate and compare the association of soluble adhesion molecules and C-reactive protein levels with the prevalence of SBI in patients with and without diabetes mellitus. We recruited 130 patients (mean age 59.6 ± 7.6 yrs) with type 2 diabetes and 130 age- and sex-matched non-diabetic subjects. All subjects underwent head MRI to determine SBI. We measured levels of soluble intercellular adhesion molecule 1(sICAM-1), vascular cell adhesion molecule 1(sVCAM- 1), and high sensitivity C-reactive protein (hs-CRP) and evaluated intima-media complex thickness (IMT) in common carotid arteries by ultrasound B-mode imaging. SBI was present in 36 ( 27.7%) of the diabetic patients and 31 ( 23.8%) of the non-diabetic subjects. Levels of sICAM-1, sVCAM-1 and IMT were all significantly higher in diabetic patients than in non-diabetic subjects, and were significantly increased in both subjects with SBI. IMT was only positively correlated with sVCAM-1 levels in diabetic and non-diabetic subjects. On the other hand, hs-CRP levels were not significantly different in both subjects with and without SBI. In addition, sICAM-1 levels were associated with a significantly higher relative risk for the prevalence of SBI in diabetic patients after multivariate adjustment. Our study suggests that the associations between endothelial dysfunction and presence of SBI may be stronger in diabetic patients than in nondiabetic subjects. In particular, sICAM-1 may play an important role for the pathogenesis of SBI in patients with diabetes mellitus.

In the brain after infarction or trauma, the tissue becomes pannecrotic and forms a cavity. In such situation, a scaffold is necessary to produce new tissue. In this study, we implanted a new porous gelatin-siloxane hybrid derived from gelatin and 3-(glycidoxypropyl) trimethoxysilane (gelatin-GPTMS) scaffolds into a brain defect, and investigated whether it makes a new brain tissue. In addition, vascular endothelial growth factor (VEGF) was added on gelatin- GPTMS scaffolds and its effect on tissue regeneration was examined. At 30 days after the implantation, the marginal territory of the scaffolds became occupied by newly formed tissue. Immunohistochemical analysis revealed that the new tissue was constituted by endothelial, astroglial and microglial cells, some of which were labeled for bromodeoxyuridine (BrdU). Addition of VEGF promoted numbers of these cells. Thus, combination of gelatin-GPTMS scaffolds and VEGF is preferable for brain regeneration.

Monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein (MIP-1α) are implicated in monocyte infiltration into the central nervous system (CNS) under pathological conditions. We previously showed that in vivo human umbilical cord blood cells (HUCB) migrate toward brain injury after middle cerebral artery occlusion (MCAO). We hypothesized that MCP-1 and MIP-1α may participate in the recruitment of HUCB towards the injury. Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO), and 24 hours later the production of MCP-1 and MIP-1α in the brain was examined with immunohistochemistry, ELISA, and western blotting. The chemotactic effect of MCP-1 and MIP-1α, and the expression of MCP-1 receptor CCR2 and MIP-1α receptor CCR1, CCR5 on the surface of HUCB were also examined. MCP-1 and MIP-1α expression were significantly increased in the ischemic hemisphere of brain, and significantly promoted HUCB cell migration compared to the contralateral side. This cell migration was neutralized with polyclonal antibodies against MCP-1 or MIP-1α. Also chemokine receptors were constitutively expressed on the surface of HUCB cells. The data suggested that the increased chemokines in the ischemic area can bind cell surface receptors on HUCB, and induce cell infiltration of systemically delivered HUCB cells into the CNS in vivo.

Unmitigated oxidative stress can lead to diminished cellular longevity, accelerated aging, and accumulated toxic effects for an organism. Current investigations further suggest the significant disadvantages that can occur with cellular oxidative stress that can lead to clinical disability in a number of disorders, such as myocardial infarction, dementia, stroke, and diabetes. New therapeutic strategies are therefore sought that can be directed toward ameliorating the toxic effects of oxidative stress. Here we discuss the exciting potential of the growth factor and cytokine erythropoietin for the treatment of diseases such as cardiac ischemia, vascular injury, neurodegeneration, and diabetes through the modulation of cellular oxidative stress. Erythropoietin controls a variety of signal transduction pathways during oxidative stress that can involve Janus-tyrosine kinase 2, protein kinase B, signal transducer and activator of transcription pathways, Wnt proteins, mammalian forkhead transcription factors, caspases, and nuclear factor κB. Yet, the biological effects of erythropoietin may not always be beneficial and may be poor tolerated in a number of clinical scenarios, necessitating further basic and clinical investigations that emphasize the elucidation of the signal transduction pathways controlled by erythropoietin to direct both successful and safe clinical care.

HspB5/αB-crystallin (αBC), one of the most representative member of mammalian small heat shock protein family (sHsp), shares the common features with other nine members HspB1-B4 and HspB6-10. Meanwhile, it has a strong antiapoptic effect; its interaction with cytoskeleton participates in maintaining cell structure and plays an important role in cytoprotection. Recent studies reveal that HspB5 has a strong relationship with neurological diseases acting as a protective molecular chaperone or in certain conditions, a pathogenic factor. This review gives a brief introduction on properties of HspB5, its current progress in neurological diseases and potential therapeutic intervention in demyelinating disease, neurodegenerative disease, myopathy and cerebrovascular disease.