In utero gene therapy: the case for

Activation of NF-kB and ERK1/2 after permanent focal ischemia is abolished by simvastatin treatment

We investigated the effects of simvastatin treatment on the expression of IL-1beta and MCP-1, the activity of NF-kB, and the signaling pathways related to NF-kB activation in a rat model of permanent middle cerebral artery occlusion (pMCAO). IL-1beta and MCP-1 expression, determined using RT-PCR, was enhanced by pMCAO; this effect was inhibited by the administration of simvastatin before ischemia. Pre-treatment with simvastatin abolished the ischemia-induced activation of NF-kB observed in vehicle-treated animals. The evaluation of signal transduction pathways, including extracellular signal-regulated kinase (ERK1/2), SAPK/JNK 46/54 and p38, indicated that only ERK1/2 phosphorylation was enhanced by ischemia, and this activation was prevented by simvastatin. ERK1/2-inhibitor, U0126, reduced brain ischemia but not cytokine induction. These results provide evidence that the HMG-CoA reductase inhibitor induces its effect in the protection of ischemic brain damage with a more complex mechanism which also involve anti-inflammatory properties rather than simple inhibition of ERK1/2 signaling pathway.

Paeoniflorin attenuates chronic cerebral hypoperfusion-induced learning dysfunction and brain damage in rats

Chronic cerebral hypoperfusion, a mild ischemic condition, is associated with the cognitive deficits of AD. Paeoniflorin (PF), a major constituent of peony root, was proved to be neuroprotective in middle cerebral artery occlusion model. In this study, we investigated whether PF could attenuate chronic cerebral hypoperfusion-induced learning dysfunction and brain damage in rat. Seven weeks after permanent bilateral occlusion of the common carotid arteries, the rats were tested in the Morris water maze. Subsequently, the animals were sacrificed and neurons, astrocytes and microglias were labeled with immunocytochemistry in hippocampus. PF at the dose of 2.5 mg/kg ameliorated cerebral hypoperfusion-related learning dysfunction and prevented CA1 neuron damage. Chronic cerebral hypoperfusion increased the immunoreactivity of astrocytes and microglias in hippocampus. The increase was prevented by PF at the dose of 2.5 mg/kg. Cerebral hypoperfusion also increased expression of nuclear factor-kappaB (NF-kappaB), mostly in astrocytes, but not in neurons. With the treatment of PF (2.5 mg/kg), NF-kappaB immunostaining was diminished in hippocampus. Our results demonstrated that PF could attenuate cognitive deficit and brain damage induced by chronic cerebral hypoperfusion and that suppression of neuroinflammatory reaction in brain might be involved in PF-induced neuroprotection.

Long-term gene expression changes in the cortex following cortical ischemia revealed by transcriptional profiling

Cerebral ischemia evokes changes in gene expression time-dependently after the ischemic event. Most studies on transcriptional changes following ischemia have centered on relatively early postischemic time points, and detected multiple genes relevant to neuronal cell death. However, functional outcome after ischemia depends critically on adaptations of the postischemic brain. Plasticity may derive from network-inherent changes, or from the formation of new nerve cells in the CNS. We have screened for gene expression changes up to 3 weeks following a limited photothrombotic cortical insult in the rat sensorimotor cortex by using the sensitive restriction-mediated differential display (RMDD) technique. A high number of genes were detected as induced at early or intermediate time points in the ipsi- and contralateral cortex (6 and 48 h). Unexpectedly, at the late time point examined (3 weeks), we still detected 40 genes that were changed in their expression. We further characterized the expression of two genes linked to neurogenesis (nestin and stathmin), and two genes likely involved in reconfiguring neuronal networks (semaphorin VIa and synaptotagmin IV). Conclusively, our data highlight the degree of long-term transcriptional changes in the cortex after ischemia, and provide insight into functional pathways of relevance for compensatory recovery mechanisms in neural networks.

Age-related neural degeneration in nuclear-factor κB p50 knockout mice

Nuclear factor-kappaB is a transcription factor that regulates a variety of genes involved not only with immune and inflammatory responses, but also in cell survival. Nuclear-factor kappaB in the CNS is an area of current research interest; however, its role in age-related neural degeneration is obscure. The present study examines developmental degeneration changes in wild type and nuclear factor-kappaB p50 subunit knockout mice (p50-/-) using various morphological methodologies. P50-/- mice appeared normal at birth. At 6 and 10 months old, the body weight of p50-/- mice was significantly less than that of wild type mice and they started to die from aging. Consistently, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling positive cells in the cortex were significantly more in p50-/- mice than that in wild type mice, and neuronal cells in the cortex, hippocampus and caudate nucleus-putamen decreased in p50-/- mice. Fewer myelinated axons of the optic nerve were found in p50-/- mice than in wild type mice at 6 months. In p50-/- mice, morphological examinations showed: 1) aging and degenerative changes in the cortex and hippocampus including increased lipofuscin granules in neural cytoplasm, 2) abnormal capillaries, 3) dark and watery alterations and organelle accumulations, 4) apoptotic glia cells, and 5) terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling and caspase-3 positive neurons. These results suggest that nuclear-factor kappaB may play an important role in neurovascular development, cell survival, and the aging process in the CNS. This new evidence linking nuclear-factor kappaB to myelination and aging may be of considerable importance for several areas of basic and clinical neuroscience.

Distinct nuclear factor-kappaB/Rel proteins have opposing modulatory effects in glutamate-induced cell death in HT22 cells

Members of the nuclear factor-kappaB (NF-kappaB)/Rel family (p50, p52, p65 (RelA), RelB and c-Rel) is sequestered in the cytoplasm through its tight association with the inhibitor of NF-kappaB (IkappaB). NF-kappaB has been shown to function as key regulators of either cell death or survival in neurons after activation of the cells by various extracellular signals. In the study presented here, we investigated whether the selective activation of diverse NF-kappaB/Rel family members in HT22 cells might lead to distinct effects on glutamate-induced cell death. Exposing HT22 cells to glutamate, which blocks cystine uptake into the cells via inhibition of the glutamate-cystine antiporter, resulted in a transient activation of IkappaB and NF-kappaB/Rel and caused delayed cell death. Aspirin, which has been shown to block phosphorylation of the IkappaB component of the cytoplasmic NF-kappaB complex, significantly suppressed glutamate-induced cell death, whereas the NF-kappaB decoy oligonucleotide potentiated it. The inhibition of NF-kappaB/Rel protein expression by antisense oligonucleotides showed that p65 is involved in glutamate-mediated cell death, whereas p50 is involved in inhibitory pathways of the cell death. These findings suggest that in HT22 cells, the balance between promoting and presenting cell death to glutamate-induced oxidative stress relies on the activation of distinct NF-kappaB proteins.

Signaling via NF-κB in the nervous system

Nuclear factor kappa B (NF-kappaB) is an inducible transcription factor present in neurons and glia. Recent genetic models identified a role for NF-kappaB in neuroprotection against various neurotoxins. Furthermore, genetic evidence for a role in learning and memory is now emerging. This review highlights our current understanding of neuronal NF-kappaB in response to synaptic transmission and summarizes potential physiological functions of NF-kappaB in the nervous system. This article contains a listing of NF-kappaB activators and inhibitors in the nervous system, furthermore specific target genes are discussed. Synaptic NF-kappaB activated by glutamate and Ca2+ will be presented in the context of retrograde signaling. A controversial role of NF-kappaB in neurodegenerative diseases will be discussed. A model is proposed explaining this paradox as deregulated physiological NF-kappaB activity, where novel results are integrated, showing that p65 could be turned from an activator to a repressor of anti-apoptotic genes.

Neuroprotection by IL-10-producing MOG CD4+ T cells following ischemic stroke

Mucosal tolerance has been used successfully to treat animal models of autoimmune diseases and is being tested in human diseases. In this work we demonstrate the reduction of infarct size following mucosal tolerance by myelin oligodendrocyte glycoprotein (MOG) (35-55) peptide in mouse stroke model. Nasal MOG was most efficacious and reduced ischemic infarct size by 70% at 24 h as well as improving behavior score. Using immunohistological methods and IL-10 -/- mice, we demonstrate the importance of IL-10-producing CD4+ T cells in the reduction of the ischemic infarct volume following middle cerebral artery occlusion (MCAO). Furthermore, adoptive transfer of CD4+ T cells from nasally tolerized mice to untreated mice prior to MCAO surgery significantly decreased stroke size (p<0.001 vs. control), whereas CD4+ T cells from nasally tolerized IL-10-deficient mice had no significant effect. Based on these results, modulation of cerebral inflammation by mucosal tolerance to myelin antigens may have applicability both as prophylactic therapy and treatment following ischemia attacks.

Gestational age of recipient determines pattern and level of transgene expression following in utero retroviral gene transfer

The direct vector injection approach was used in the fetal sheep model of in utero gene therapy to determine the effects of the recipient gestational age on the efficacy and pattern of liver, lung, and brain transduction and transgene expression. The livers contained foci of transgene-expressing hepatocytes and demonstrated an inverse correlation between recipient age and hepatocyte transduction/transgene expression, with higher levels of gene transfer/expression early in gestation and lower levels late in gestation. Conversely, the percentage of transgene-expressing cells within the lungs of these same animals increased with gestational age, with the majority of transduction occurring in epithelium and fibroblasts. In contrast to the lung and liver, transgene-expressing cells within the brain were extremely limited at all gestational ages tested. Our results demonstrate that numerous nonhematopoietic cells within the liver and lung are transduced following direct injection of murine retroviral vectors into fetal sheep and suggest that the developmental stage of each organ at the time of injection may determine its susceptibility to in utero gene transfer and subsequent levels of transgene expression. Our results suggest that with further vector optimization this approach may be useful for treating diseases that involve the lung and liver early in development.

Post-ischemic inflammation: molecular mechanisms and therapeutic implications

Ischemic stroke is characterized by the disruption of cerebral blood flow (CBF). This reduction of CBF results in energy failure and secondary biochemical disturbances, eliciting a robust in situ inflammatory response. Post-ischemic inflammation is a dynamic process involving a complicated set of interactions among various inflammatory cells and molecules. The resident inflammatory brain cells, microglia, are especially activated in response to ischemic insults, many of which are regulated by nuclear transcription factor, kappa B (NF-kappaB). As a result, several inflammatory genes are expressed, leading to local generation of various cytokines, which in turn promulgate inflammatory signals. Meanwhile, endothelial cells lining the local cerebral blood vessels are stimulated to produce adhesion molecules, causing the migration of peripheral circulating leukocytes into the compromised brain tissue, an event that amplifies inflammatory signaling cascades. Post-ischemic inflammation appears to serve multiple purposes, depending on its timing and magnitude, as well as the topographic distribution of various inflammatory molecules. Data from experimental manipulations of some inflammatory molecules are yielding insight into therapeutic strategies for ischemic stroke. This review focuses on some recent advances regarding the regulation of inflammatory signaling pathways, the detrimental effects of post-ischemic inflammation and the potential molecular targets for ischemic stroke therapy.

Nonviral gene transfer to surface skin of mid-gestational murine embryos by intraamniotic injection and subsequent electroporation

The surface epithelium of mid-gestational murine embryos is thought to be an attractive target for gene therapy in vivo, due to its visibility and accessibility from the external surface of the maternal uterus. Almost all studies of in utero gene transfer have adopted viral vectors for infection of fetal epithelium, and depended on intraamniotic introduction and simple incubation of vectors, leading to only infection of the surface layer (periderm) of fetal skin. Here we report a simple and convenient method of gene transfer of plasmid DNA into the deeper portion of surface skin of murine mid-gestational fetus. One to two microlitres of a solution containing a lacZ expression plasmid (0.5-1 microg) and trypan blue (0.05%) were placed onto the surface of a fetus (E 14.5) near the eye by a micropipette attached to a mouthpiece. This fetus was immediately electroporated by placing it between tweezer-type electrodes attached to a square-pulse generator. At 1 and 4 days after gene transfer, fetuses were subjected to histochemical staining for lacZ activity in the presence of X-Gal, a substrate for lacZ. Focal reactions were observed in the skin epidermal layers including periderm and basal layer 1 day after DNA introduction. However, lacZ-positive cells were limited to a skin surface layer, the stratum corneum, in the samples obtained 4 days after gene transfer. Similar observation was also made in the transgenic fetuses (carrying a lacZ gene placed immediately downstream of the loxP-flanked sequence) injected with Cre expression vector. These findings suggest rapid movement of fetal epidermal cells toward the surface during late developmental stages. This local gene transfer approach appears to be effective as a method for skin-targeted gene transfer, enabling study of the role of genes of interest and tracing of cell lineage during fetal skin development.

The cannabinoid dexanabinol is an inhibitor of the nuclear factor-kappa B (NF-kappa B)

Exogenous and endogenous cannabinoids have been shown to have neuroprotective effects in vitro and in vivo. Although many of the pharmacological effects of cannabinoids have been identified, the mechanism of neuroprotection still represents a controversy. Here we demonstrate for the first time protective effects of the synthetic cannabinoid dexanabinol by inhibiting apoptosis in a neuron-like cell line using nuclear staining and FACS analysis and in primary neurons. We provide further evidence of inhibition of nuclear factor-kappakappa B (NF-kappaB) by dexanabinol: Dexanabinol inhibits (1) phosphorylation and degradation of the inhibitor of NF-kappaB IkappaBalpha and translocation of NF-kappaB to the nucleus; dexanabinol reduces (2) the transcriptional activity of NF-kappaB and (3) mRNA accumulation of the NF-kappaB target genes tumor necrosis factor-alpha and interleukin-6 (TNF-alpha and IL-6). Dexanabinol does not bind to cannabinoid (CB) receptors 1 and 2. To investigate the mechanism of action, we employed the non-antioxidant CB1 receptor agonist WIN 55,212-2 and the antioxidant cannabinol, which binds to CB1 receptors only weakly. Both cannabinoids mimicked the effect of dexanabinol on NF-kappaB and apoptosis. This suggests that neither the antioxidant properties of cannabinoids nor binding to CB1 or CB2 receptors are responsible for the inhibition of NF-kappaB activity and apoptosis. Our results clearly demonstrate that dexanabinol inhibits NF-kappaB. NF-kappaB has been shown to be involved in brain damage and to promote neuronal cell death in vitro and in in vivo models of ischemic and neurodegenerative neurological diseases.

Inhibition of IκBα phosphorylation prevents glutamate-induced NF-κB activation and neuronal cell death

NF-kappaB is a nuclear transcription factor involved in the control of fundamental cellular functions including regulation of cell survival. We investigated NF-kappaB activation induced by two opposing modulators of cell viability: IL-1beta and glutamate. We found that IL-1beta activated p50, p65 and c-Rel subunits of NF-kappaB, while glutamate activated only p50 and p65 proteins. Cell stimulation by glutamate, correlated with expression of the pro-apoptotic genes Caspase-3, Caspase-2L and Bax. Conversely, IL-1beta induced the expression of the short anti-apoptotic isoform of Caspase-2. Finally, we analysed the effect of the inhibition of IkappaBalpha degradation on glutamate-induced toxicity by using BAY 11-7082, a selective inhibitor of IkappaBalpha phosphorylation. Our results suggest that BAY 11-7082 preserves neuron viability from the glutamate-mediated injury.

No evidence for germ-line transmission following prenatal and early postnatal AAV-mediated gene delivery

BACKGROUND

Recombinant adeno-associated viruses have been used successfully in a number of pre-clinical and clinical gene therapy studies. Since there is a broad consensus that gene therapy must not lead to germ-line transmission, the potential of such vectors for inadvertent gene transfer into germ cells deserves special attention. This applies in particular to pre- or perinatal vector application which has been considered for diseases presenting with morbidity already at birth.

METHODS

AAV serotype 2 derived vectors carrying a beta-galactosidase reporter gene or human clotting factor IX cDNA were injected intraperitoneally or via a yolk sac vein into mouse fetuses or administered intravascularly to newborn mice. Tissue samples of the treated animals including the gonads as well as sperm DNA, obtained by differential lysis of one testis of each male animal, and the offspring of all treated mice were investigated for the presence of vector DNA by nested PCR. In positive samples, the copy number of the vector was determined by quantitative real-time PCR.

RESULTS

AAV vectors administered intraperitoneally or intravascularly to fetal or newborn mice reached the gonads of these animals and persisted there for time periods greater than one year. Intravascular injection of the vector resulted more frequently in gene transfer to the gonads than intraperitoneal injection. Vector copy numbers in the gonads ranged from 0.3 to 74 per 10(4) cell equivalents. However, neither in isolated sperm DNA from the treated animals nor in their offspring were vector sequences detectable.

CONCLUSIONS

These data suggest the risk of inadvertent germ-line transmission following prenatal or early postnatal AAV type 2 mediated gene delivery to be very low.

The inhibitor of I kappa B alpha phosphorylation BAY 11-7082 prevents NMDA neurotoxicity in mouse hippocampal slices

NF-kappaB is a nuclear transcription factor involved in the control of fundamental cellular functions including cell survival. Among the many target genes of this factor, both pro- and anti-apoptotic genes have been described. To evaluate the contribution of NF-kappaB activation to excitotoxic insult, we analysed the effect of IkappaBalpha (IkappaBalpha) phosphorylation blockade on glutamate-induced toxicity in adult mouse hippocampal slices. By using immunocytochemical and EMSA techniques, we found that (i) acute exposure of hippocampal slices to NMDA induced nuclear translocation of NF-kappaB, (ii) NMDA-mediated activation of NF-kappaB was prevented by BAY 11-7082, an inhibitor of IkappaBalpha phosphorylation and degradation, and (iii) BAY 11-7082-mediated inhibition of NF-kappaB activation was associated with neuroprotection.

Death effectors of beta-cell apoptosis in type 1 diabetes

While it is generally agreed that apoptosis of pancreatic beta-cells is the most important and final step in the progression of type 1 diabetes without which clinical diabetes does not develop, it has not been elucidated which molecule(s) are the real culprit(s) in type 1 diabetes. Perforin, FasL, TNFalpha, IL-1, IFNgamma, and NO have been claimed as the effector molecules; however, they, as a single agent, might explain only part of beta-cell death in type 1 diabetes. While FasL was initially considered as a strong candidate for the most important death effector, following experiments cast doubt on such a hypothesis. Combinations or synergism between IFNgamma and TNFalpha or IL-1beta are being revisited as the death effectors, and molecular mechanism explaining such a synergism was addressed in several recent papers. The role of NF-kappaB for pancreatic beta-cell death in type 1 diabetes is also controversial. While NF-kappaB plays anti-apoptotic roles in most other death models, its role in type 1 diabetes might be different probably due to the involvement of multiple cytokines at different stages of the disease progression and the peculiarity of pancreatic beta-cells. Recent papers also suggested a role for Ca2+ in cytokine-mediated pancreatic beta-cell death. Such participation of Ca2+ in beta-cell death appears to have a close relevance to the mitochondrial events or ER stress that constitutes an important part of cell death machinery recently identified.

Nuclear factor kappa B—molecular biomedicine: the next generation

Nuclear factor kappa B (NFkappaB) as a transcription factor plays an important integrating role in the intracellular regulation of immune response, inflammation and cell cycle regulation. Nouvelle insights into the structure and regulation of activation of NFkappaB have brought a detailed picture of the function of this transcription factor. In this review the findings of interactions of NFkappaB with its inhibitors, tumour necrosis factor alpha and glucocorticoids are presented. The results from the latest in vivo studies show the capability of specific NFkappaB inhibitors in the clinical use. This article summarizes the most important facts regarding NFkappaB participation in the pathogenesis of diseases and its potential as a target of pharmacological agents.

Involvement of Rel/NF-kappa B transcription factors in senescence

Senescence is now established as a genetically controlled phenomenon that alters different cell functions, including proliferation, apoptosis, resistance to stress, and energetic metabolism. Underlying changes in gene expression are governed by some transcription factors, whose expression or activity must change with senescence as well. Transcription factors of the Rel/NF-kappa B family are good candidates to participate in the establishment of senescence. Arguments range from correlation between cell functions controlled by these factors and cell functions altered during senescence, to phenotypes resulting from in vitro manipulations of Rel/NF-kappa B activity.

Identification of regulated genes during transient cortical ischemia in mice by restriction-mediated differential display (RMDD)

Cerebral ischemia induces transcriptional changes in a number of pathophysiologically important genes. Here we have systematically studied gene expression changes in the cortex after 150 min of focal cortical ischemia and 2 and 6 h reperfusion in the mouse by a fragment display technique (restriction-mediated differential display, RMDD). We identified 57 transcriptionally altered genes, of which 46 were known genes, and 11 unknown sequences. Of note, 14% of the regulated genes detected at 2 h reperfusion time were co-regulated in the contralateral cortex. Four genes were verified to be upregulated by quantitative PCR. These were Metallothionein-II (mt2), Receptor (calcitonin)-activity modifying protein 2 (ramp2), Mitochondrial phosphoprotein 65 (MIPP65), and the transcription elongation factor B2/elongin B (tceb). We could identify several genes that are known to be induced by cerebral ischemia, such as the metallothioneins and c-fos. Many of the genes identified provide hints to potential new mechanisms in ischemic pathophysiology. We discuss the identity of the regulated genes in view of their possible usefulness for pharmacological intervention in cerebral ischemia.

Evaluation of neuronal cell death after a new global ischemia model in infant mice

For the first time we set up a new model for global ischemia in the infant mice, and time-dependent changes of the blood-brain barrier (BBB) disruption and neuronal cell death were investigated in detail. Infant C57/B16 mice (postnatal 13 days) were anesthetized with inhalation of sevoflurane in N2O/O2 (70/30%) and were subjected to global ischemia by bilateral common carotid artery occlusion (CCAO) for 25 minutes. Disruption of BBB was noted at 4 hours and increased up to 24 hours after the injection of 2% Evan's Blue in the transient CCAO (tCCAO) model. Evaluation of neuronal cell death was determined with toluidine blue staining. Morphological changes of neurons after tCCAO were clearly observed in the hippocampal CA1 region but were slightly detected in the CA3 region. However, there were no morphological changes in the hippocampal dentate gyrus, the neocortex, the striatum and the hypothalamus. The number of survival neurons in the CA1 was significantly decreased at 2 days and sustained up to 4 days after tCCAO. These data indicate that this method is very useful to induce selective vulnerability in mouse hippocampus, and it provides a reliable ischemic model in infant mice.

In vivo heat-shock response in the brain: signalling pathway and transcription factor activation

We analysed the expression of the hsp70 gene, the phosphorylation status of different members of the mitogen-activated protein kinase (MAPK) family, the behaviour of the Akt-GSK3 pathway, as well as the DNA-binding activity of several transcription factors, potential targets of these kinases, in the brain of rats exposed to a fever-like increase in body temperature. Two different brain regions, the cerebellum and the hippocampus, were studied. Hyperthermia caused HSF activation and the induction of hsp70 mRNA and protein to a greater extent in the cerebellum than in the hippocampus. In the cerebellum, ERK1/2 and p38 MAPK phosphorylation were increased by hyperthermia and returned to basal levels during the recovery from heat stress, whereas JNK3 phosphorylation decreased and recovered to above control levels within 60 min of recovery. JNK1 phosphorylation was never modified. In the hippocampus, ERK phosphorylation did not increase but rather decreased, whereas the behaviour of p38 MAPK and JNK was similar to that observed in the cerebellum. Akt phosphorylation increased after hyperthermia and was accompanied by an increased phosphorylation of two substrates, GSK3 and FKHRL1, in both brain areas, with a major effect in the cerebellum. DNA-binding activities of AP-1, NF-kappaB, and MEF2 were activated by heat shock in the cerebellum, whereas only MEF2 was activated in the hippocampus. Our data indicate that a physiologically relevant increase in body temperature induces brain injury and survival response to it as demonstrated by induction of hsp70 gene expression and activation of specific signalling pathways. Reprogramming of gene expression, by the specific transcription factors activated, probably plays a central role in cell adaptation and survival to heat stress. The hippocampus shows less responsiveness to hyperthermia than the cerebellum.

Evidence that activation of nuclear factor-kappaB is essential for the cytotoxic effects of doxorubicin and its analogues

Several reports within the last 5 years have suggested that nuclear factor (NF)-kappaB activation suppresses apoptosis through expression of anti-apoptotic genes. In the present report, we provide evidence from four independent lines that NF-kappaB activation is required for the cytotoxic effects of doxorubicin. We used doxorubicin and its structural analogues WP631 and WP744, to demonstrate that anthracyclines activate NF-kappaB, and this activation is essential for apoptosis in myeloid (KBM-5) and lymphoid (Jurkat) cells. All three anthracyclines had cytotoxic effects against KBM-5 cells; analogue WP744, was most potent, with an IC(50) of 0.5 microM, and doxorubicin was least active, with an IC(50) of 2 microM. We observed maximum NF-kappaB activation at 1 microM with WP744 and at 50 microM with doxorubicin and WP631, and this activation correlated with the IkappaBalpha degradation. Because the anthracycline analogue (WP744), most active as a cytotoxic agent, was also most active in inducing NF-kappaB activation and the latter preceded the cytotoxic effects, suggests that NF-kappaB activation may mediate cytotoxicity. Second, receptor-interacting protein-deficient cells, which did not respond to doxorubicin-induced NF-kappaB activation, were also protected from the cytotoxic effects of all the three anthracyclines. Third, suppression of NF-kappaB activation by pyrrolidine dithiocarbamate, also suppressed the cytotoxic effects of anthracyclines. Fourth, suppression of NF-kappaB activation by NEMO-binding domain peptide, also suppressed the cytotoxic effects of the drug. Overall our results clearly demonstrate that NF-kappaB activation and IkappaBalpha degradation are early events activated by doxorubicin and its analogues and that they play a critical pro-apoptotic role.

Endocrine aspects of cancer gene therapy

The field of cancer gene therapy is in continuous expansion, and technology is quickly moving ahead as far as gene targeting and regulation of gene expression are concerned. This review focuses on the endocrine aspects of gene therapy, including the possibility to exploit hormone and hormone receptor functions for regulating therapeutic gene expression, the use of endocrine-specific genes as new therapeutic tools, the effects of viral vector delivery and transgene expression on the endocrine system, and the endocrine response to viral vector delivery. Present ethical concerns of gene therapy and the risk of germ cell transduction are also discussed, along with potential lines of innovation to improve cell and gene targeting.

S100B potently activates p65/c-Rel transcriptional complexes in hippocampal neurons: Clinical implications for the role of S100B in excitotoxic brain injury

Increased serum levels of S100B are positively correlated with multiple forms of CNS damage, such as stroke, CNS trauma and neurodegenerative diseases, but also in psychiatric disorders. However, it is currently not known whether increased serum levels of S100B reflect a neuroregenerative or neurodegenerative response. Since glutamate receptor overactivation (excitotoxicity) may contribute to neuronal pathology in psychiatric disorders, we investigated the effect of S100B on N-methyl-d-aspartate (NMDA)-induced neuronal cell death. Here we demonstrate that very low concentrations of S100B significantly protect primary rat hippocampal neurons against NMDA toxicity by activation of transcription factors of the Rel/nuclear factor kappaB (NF-kappaB) family. Further experiments suggest that i) S100B activated expression of the receptor of advanced glycation products (RAGE) gene in neurons and ii) S100B induced a unique composition of the active NF-kappaB complex consisting of the p65 and c-Rel subunits suggesting a novel mechanism for NF-kappaB activation involved in S100B-mediated neuroprotection. Our data suggest that S100B secreted during the glial response to brain injury potently activates p65/c-Rel in a RAGE-dependent manner and may exert neuroprotective and neuroregenerative effects in psychiatric disorders.

Microarray analysis of tumor necrosis factor alpha induced gene expression in U373 human glioblastoma cells

BACKGROUND

Tumor necrosis factor alpha (TNF) is able to induce a variety of biological responses in the nervous system including inflammation and neuroprotection. Human astrocytoma cells U373 have been widely used as a model for inflammatory cytokine actions in the nervous system. Here we used cDNA microarrays to analyze the time course of the transcriptional response from 1 h up to 12 h post TNF treatment in comparison to untreated U373 cells. TNF activated strongly the NF-kappaB transcriptional pathway and is linked to other pathways via the NF-kappaB target genes JUNB and IRF-1. Part of the TNF-induced gene expression could be inhibited by pharmacological inhibition of NF-kappaB with pyrrolidine-dithiocarbamate (PDTC). NF-kappaB comprises a family of transcription factors which are involved in the inducible expression of genes regulating neuronal survival, inflammatory response, cancer and innate immunity.

RESULTS

In this study we show that numerous genes responded to TNF (> 880 from 7500 tested) with a more than two-fold induction rate. Several novel TNF-responsive genes (about 60% of the genes regulated by a factor > or = 3) were detected. A comparison of our TNF-induced gene expression profiles of U373, with profiles from 3T3 and Hela cells revealed a striking cell-type specificity. SCYA2 (MCP-1, CCL2, MCAF) was induced in U373 cells in a sustained manner and at the highest level of all analyzed genes. MCP-1 protein expression, as monitored with immunofluorescence and ELISA, correlated exactly with microarray data. Based on these data and on evidence from literature we suggest a model for the potential neurodegenerative effect of NF-kappaB in astroglia: Activation of NF-kappaB via TNF results in a strongly increased production of MCP-1. This leads to a exacerbation of neurodegeneration in stoke or Multiple Sclerosis, presumably via infiltration of macrophages.

CONCLUSIONS

The vast majority of genes regulated more than 3-fold were previously not linked to tumor necrosis factor alpha as a search in published literature revealed. Striking co-regulation for several functional groups such as proteasome and ribosomal proteins were detected.

Evaluation of MCAO stroke models in normotensive rats: standardized neocortical infarction by the 3VO technique

The temporary three-vessel occlusion (3VO) technique with a surgical approach for middle cerebral artery (MCA) produces consistent cerebral infarction in the neocortex in normotensive rats. The intraluminal thread-occlusion technique with an endovascular approach targeting the MCA occlusion (MCAO) is more widely used since it does not require complicated intracranial procedures. The aim of this study was to review the methods/models for MCAO stroke in normotensive rats and to evaluate a 3VO stroke model that provides consistent degrees and variance of cortical stroke injury for additional discussion. First, we analyzed a model with modified temporary 3VO technique requiring less complicated procedures than the temporary 3VO model, i.e., temporary occlusion of the bilateral common carotid arteries (CCAs) superimposed on a permanent occlusion of the MCA, in Sprague-Dawley rats or C57BL/6J mice. In the microvascular tissue (cerebral) perfusion study, significant reductions in regional cerebral perfusion during the 3VO accompanied a rapid return to baseline after release of the CCAs, showing that the technique induces temporary focal ischemia. The average sizes and variances of the neocortical infarction in this model, together with those in the other normotensive rat models caused by the 3VO technique in the literature, indicated a standard size and variance of infarcted lesion in the control groups relative to the specific ischemic period. However, stroke injuries in the neocortex induced by the thread occlusion technique showed greater variability with less consistent lesion sizes. Inclusion/exclusion criteria to avoid inappropriate cases with too mild (no/faint infarction) or too great (huge/fatal infarction) severity in the ischemic injury may differ between laboratories in the thread occlusion model.

Alpha-melanocyte-stimulating hormone is decreased in plasma of patients with acute brain injury

The neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH) is a proopiomelanocortin derivative that has potent anti-inflammatory influences within the brain. The aim of the present research was to determine if there are changes in blood concentrations of this peptide in patients with acute traumatic brain injury (TBI) or subarachnoid hemorrhage (SAH). Concomitantly, we recorded clinical parameters and measured blood concentrations of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha). Twenty-three patients were enrolled in this study--18 had TBI and five SAH. Blood samples for determination of alpha-MSH and TNF-alpha were collected daily from day 1 to day 4 after injury. Baseline concentration of plasma alpha-MSH in patients with acute brain injury of either traumatic or vascular origin was significantly lower than in controls. Patients with TBI or SAH had similar alpha-MSH concentrations and the peptide remained consistently low over four post-injury days. Circulating TNF-alpha on day one was measurable in all patients and there was a negative correlation between plasma TNF-alpha and alpha-MSH. Alpha-MSH was measured again after the acute phase in eight patients. The peptide was substantially increased in all subjects except for two who had an unfavorable outcome. From the well-known protective anti-inflammatory influences of alpha-MSH in the host, reduction in this circulating peptide may have detrimental consequences in brain injury. The data raise the possibility that restoration of normal circulating alpha-MSH through administration of the peptide could be beneficial in patients with brain injury.

Signal transduction and neurosurvival in experimental models of brain injury

Brain injury and neurodegenerative disease are linked by their primary pathological consequence-death of neurons. Current approaches for the treatment of neurodegeneration are limited. In this review, we discuss animal models of human brain injury and molecular biological data that have been obtained from their analysis. In particular, signal transduction pathways that are associated with neurosurvival following injury to the brain are presented and discussed.

Recombinant adenoviral expression of dominant negative IkappaBalpha protects brain from cerebral ischemic injury

Transcription factor NF-kappaB is associated with inflammatory response and cell survival. Under inactive condition, NF-kappaB is sequestered in the cytoplasm by an anchor protein, inhibitor of NF-kappaB (IkappaB). NF-kappaB was shown to be activated during ischemic brain injury. In the present study we have investigated the role of NF-kappaB in ischemic brain injury using a recombinant adenovirus expressing a dominant negative form of IkappaB (Adv/IkappaBdn) to specifically inhibit NF-kappaB activation. Our data demonstrated that cortical injection of Adv/IkappaBdn significantly reduced ischemic brain injury following permanent occlusion of the middle cerebral artery (MCAO) in rats, showing 55% reduction (p<0.01, n=8) in total ischemic lesion or 80% reduction (p<0.001) in the cortical area with Adv/IkappaBdn expression. Similarly, Adv/IkappaBdn expression significantly decreased neurological deficits (37% reduction over controls, p<0.01, n=8). These data provide further evidence for the role of NF-kappaB/IkappaB in ischemic brain injury and suggest that inhibition of NF-kappaB is neuroprotective in focal stroke.

Modulation of nuclear factor-kappaB activation and decreased markers of neurological injury associated with hypothermic therapy in experimental bacterial meningitis

OBJECTIVE

This study was designed to evaluate the use of moderate hypothermia in a model of meningitis-induced brain injury and its effect on the activation of nuclear factor-kappaB, biological markers of neuronal injury, and neurobehavioral performance.

DESIGN

Randomized, prospective animal study.

SETTING

University research laboratory.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

Animals underwent a basilar cistern tap receiving either sterile saline as a placebo or an equivalent volume of a group B streptococcal suspension. Sixteen hours after inoculation, animals were stratified by their clinical severity score, were randomized to either hypothermic (32-34 degrees C) or normothermic (37-39 degrees C) conditions, and received antibiotics. Hypothermic animals were kept under these temperature conditions for 6 hrs before rewarming. Two protocols were used. For the first protocol, changes in nuclear factor-kappaB activation and heat shock protein induction at 24 hrs and 48 hrs after inoculation were evaluated. In the second protocol, serum C-tau concentrations at 5 days and neurobehavioral performances at 3 wks were assessed.

MEASUREMENTS AND MAIN RESULTS

Meningitis triggered a >50% increase in cerebral nuclear factor-kappaB activation. The addition of a 6-hr period of hypothermia reduced nuclear factor-kappaB activation by 32% when measured at the end of the hypothermic period. At 48 hrs, this decrease in nuclear factor-kappaB activation was no longer apparent, but there was a significant decrease in the heat shock response. Serum C-tau concentrations at 5 days postinjury, a biomarker of brain injury, were reduced by 69% in hypothermic treated animals. Furthermore, hypothermia reduced the brain water content of infected animals. However, hypothermia did not improve the animals' neurobehavioral performance.

CONCLUSION

The findings from this study suggest that hypothermia produces a transitory attenuation of nuclear factor-kappaB activation in meningitic brain injury and improvement in some biomarkers of neuronal injury. The consequence of intermittent suppression of nuclear factor-kappaB activation by inducing specific periods of hypothermia requires further study.

Tumor necrosis factor alpha increases neuronal vulnerability to excitotoxic necrosis by inducing expression of the AMPA-glutamate receptor subunit GluR1 via an acid sphingomyelinase- and NF-kappaB-dependent mechanism

Acid sphingomyelinase (ASMase) and NF-kappaB participate in tumor necrosis factor alpha (TNFalpha) signal transduction. Mice in which the genes encoding ASMase or the p50 subunit of NF-kappaB are disrupted have been reported to be less vulnerable than wild-type mice to focal brain ischemia. We now demonstrate selective diminution in expression of GluR1, an alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate-type glutamate receptor (AMPA-GluR) protein subunit, in these two groups of knockout mice. To confirm that neuronal GluR1 expression is regulated by ASMase and NF-kappaB, and to learn whether this regulation has pathophysiological significance, we treated cultured human NT2-N neurons with TNFalpha. This induced GluR1 expression and increased susceptibility of the neurons to kainate necrosis. Both induction of GluR1 and heightened vulnerability to kainate were blocked by inhibiting ASMase or by antisense knockdown of NF-kappaB p50. We conclude that TNFalpha can sensitize neurons to excitotoxic necrosis by inducing expression of GluR1 via an ASMase- and NF-kappaB-dependent mechanism. TNFalpha levels are frequently elevated during ischemia and other CNS diseases in which excitotoxicity contributes to neuronal loss. Our results suggest that inhibiting TNFalpha signal transduction will diminish neuronal necrosis in these diseases.

Lack of correlation between NF-kappaB activation and induction of programmed cell death in PC12 pheochromocytoma cells treated with 6-hydroxydopamine or the cannabinoid receptor 1-agonist CP55,940

NF-kappaB is a transcriptional regulator that plays a key role in immunity, inflammation and programmed cell death. We generated a PC12 cell line termed PC12kappaBluc that contains an integrated NF-kappaB-responsive reporter gene to directly measure NF-kappaB activity. The "classical" activators of NF-kappaB, phorbol 12-O-tetradecanoate-13-acetate and tumor necrosis factor alpha, strongly induced NF-kappaB activity in PC12kappaBluc cells. Activation of NF-kappaB could be attenuated by preincubating the cells with the cAMP analogue dbcAMP or via expression of the superrepressor IkappaBalphaS32A/S36A. PC12kappaBluc cells were subjected to several apoptotic paradigms, including treatment with 6-hydroxydopamine, H2O2, K2Cr2O7, MnCl2, C2-ceramide or the cannabinoid receptor-1 agonist CP55,940. A simultaneous measurement of the NF-kappaB activity revealed that only administration of 6-hydroxydopamine or CP55,940 increased NF-kappaB activity. Using pharmacological and genetic strategies to attenuate NF-kappaB transcriptional activity, we demonstrate that the elevation of NF-kappaB activity by 6-hydroxydopamine and CP55,940 is not an integral part of the apoptotic signaling cascade in PC12 cells.

Lack of NF-kappaB p50 exacerbates degeneration of hippocampal neurons after chemical exposure and impairs learning

The roles of activated NF-kappaB subunits in the CNS remain to be discerned. Members of this family of transcription factors are essential to diverse physiological processes and can be activated by pathogens, stress, pharmacological agents, and trauma. We are particularly interested in long-term NF-kappaB activation and its involvement in neuroplastic changes in the brain resulting from acquisition of memory as well as injury. Here, we use lesioning by the limbic-specific neurotoxicant trimethyltin (TMT) as a model in which to examine activation of the NF-kappaB p50 subunit before, during, and after neuronal degeneration. Neurons in wild-type mice that survived TMT-induced injury contained activated p50 and did not label with Fluoro-Jade, a histochemical marker of degenerating neurons. Granule cells of the wild-type dentate gyrus subregion, an area particularly vulnerable to TMT-induced degeneration, contained less activated p50 protein than CA regions. We compared the extent of degeneration in wild-type and p50-null mice and found a fivefold increase in death of hippocampal neurons in mice lacking p50. The hippocampus is key to processes of learning and memory, and NF-kappaB has reported involvement in these processes. The enhanced hippocampal degeneration in p50-null mice prompted us to evaluate their basal learning abilities, and we discovered that difficulties in task acquisition were an additional consequence of p50 ablation. These results indicate that absence of p50 negatively modulates learning ability as well as hippocampal responsiveness to brain injury after a chemical-induced lesion.

Fetal gene transfer by intrauterine injection with microbubble-enhanced ultrasound

Intrauterine injection of naked DNA expressing luciferase, green fluorescent protein (GFP), or beta-galactosidase (beta-gal) and fluorescein isothiocyanate-labeled oligodeoxynucleotide (FITC-ODN), in combination with microbubble-enhanced ultrasound (US), referred to as the "shotgun method" (SGM), produced high-level protein expression in fetal mice. With the SGM, luciferase expression increased approximately 10(3)-fold in comparison with expression after injection of naked DNA alone. Electron microscopic analysis demonstrated transient formation of pores on the skin surface after intraamniotic (i.a.) injection with the SGM. Widespread expression of GFP and beta-gal and delivery of FITC-ODN were observed in multiple fetal tissues adjacent to the injection points. PCR analysis indicated that germline transfection was only transient following intraperitoneal (i.p) injection, and there was no evidence of transfer of the reporter gene to the offspring. Thus, SGM might provide a useful means to clarify the molecular mechanisms of genetic diseases in utero, as well as a tool to develop gene therapies in utero.

Neuronal cell death induced by antidepressants: lack of correlation with Egr-1, NF-kappa B and extracellular signal-regulated protein kinase activation

The tricyclic antidepressants (TCA) amitriptyline and desipramine and the serotonin reuptake inhibitor fluoxetine induce, at microM concentrations, cell death in HT22 immortalized hippocampal neurons and PC12 pheochromocytoma cells. Here, we show that these neurotoxic effects are accompanied by a selective activation of extracellular signal-regulated protein kinase (ERK), the biosynthesis of the transcription factor Egr-1 and an increase in the transcriptional activity of NF-kappa B. However, an impairment of both ERK activation and Egr-1 biosynthesis by the MAP kinase kinase-1 (MEK-1) inhibitor PD98059 did not block cell death. Moreover, stimulation of ERK phosphorylation and Egr-1 biosynthesis by sphingosine-1-phosphate did not induce cell death, indicating that stimulation of the ERK signaling pathway and Egr-1 biosynthesis are not required for neuronal cell death induced by antidepressants. Likewise, attenuation of antidepressant-induced NF-kappa B activity by elevation of the intracellular cAMP concentration or by retroviral driven expression of the non-degradable superrepressor I kappa B alpha S32A/S36A demonstrated that the elevation of NF-kappa B activity by amitriptyline, desipramine and fluoxetine is not an integral part of the apoptotic signaling cascade triggered by these compounds.

Caspase-3 and the regulation of hypoxic neuronal death by vascular endothelial growth factor

Vascular endothelial growth factor (VEGF) has neurotrophic and neuroprotective as well as angiogenic properties, but the pathways involved in VEGF-mediated neuronal survival have not been identified. We found previously that VEGF protects cultured neural cells from death induced by serum withdrawal or hypoxia via the activation of VEGF-2/fetal liver kinase-1 receptors, phosphatidylinositol 3'-kinase, Akt and nuclear factor-kappa B. We now report that in mouse cortical neuron cultures subjected to hypoxia, the neuroprotective effect of VEGF involves suppression of cell-death pathways mediated by caspase-3. Exposure to hypoxia for 24 h caused the death of 71+/-4% of cultured neurons; this was reduced to 40+/-1% by VEGF (n=3, P<0.005) and to 44+/-1% by the caspase-3 inhibitor benzyloxycarbonyl-DEVD-fluoromethyl ketone (n=3, P<0.005). VEGF inhibited the activation of caspase-3 as measured by the 17-20-kDa caspase-3 cleavage product, and immunolocalization of VEGF and activated caspase-3 showed segregated expression in separate neuronal populations. An antisense, but not sense, oligodeoxyribonucleotide directed against VEGF increased the proportion of neurons expressing activated caspase-3, and correspondingly reduced the viability of hypoxic neurons by 37+/-2% (n=3, P<0.005). These findings suggest that VEGF protects neurons from hypoxic injury by inhibiting the activation of caspase-3, and could therefore act as an endogenous neuroprotective factor in cerebral ischemia.

Attenuation of 6-hydroxydopamine (6-OHDA)-induced nuclear factor-kappaB (NF-kappaB) activation and cell death by tea extracts in neuronal cultures

Antioxidant and anti-inflammatory therapy approaches have been in the focus of attention in the treatment of neurodegenerative Parkinson's and Alzheimer's diseases where oxidative stress has been implicated. Tea extracts have been previously reported to possess radical scavenger, iron chelating and anti-inflammatory properties in a variety of tissues. The purpose of this study was to investigate potential neuroprotective effects of tea extracts and possible signal pathway involved in a neuronal cell model of Parkinson's disease. We demonstrated highly potent antioxidant-radical scavenging activities of green tea (GT) and black tea (BT) extracts on brain mitochondrial membrane fraction, against iron (2.5 microM)-induced lipid peroxidation. Both extracts (0.6-3 microM total polyphenols) were shown to attenuate the neurotoxic action of 6-hydroxydopamine (6-OHDA)-induced neuronal death. 6-OHDA (350 and 50 microM) activated the iron dependent inflammatory redox sensitive nuclear factor-kappaB (NF-kappaB) in rat pheochromocytoma (PC12) and human neuroblastoma (NB) SH-SY5Y cells, respectively. Immunofluorescence and electromobility shift assays showed increased nuclear translocation and binding activity of NF-kappaB after exposure to 6-OHDA in NB SH-SY5Y cells, with a concomitant disappearance from the cytoplasm. Introduction of GT extract (0.6, 3 microM total polyphenols) before 6-OHDA inhibited both NF-kappaB nuclear translocation and binding activity induced by this toxin in NB SH-SY5Y cells. Neuroprotection was attributed to the potent antioxidant and iron chelating actions of the polyphenolic constituents of tea extracts, preventing nuclear translocation and activation of cell death promoting NF-kappaB. Brain penetrating property of polyphenols may make such compounds an important class of drugs for treatment of neurodegenerative diseases.

Sustained delivery of therapeutic concentrations of human clotting factor IX--a comparison of adenoviral and AAV vectors administered in utero

BACKGROUND

Prenatal somatic gene therapy has been considered for genetic disorders presenting with morbidity at birth. Haemophilia is associated with an increased risk of catastrophic perinatal bleeding complications such as intracranial haemorrhage, which could be prevented by gene transfer in utero. Prenatal gene therapy may be more promising than postnatal treatment, as the fetus may be more amenable to uptake and integration of therapeutic DNA and the immaturity of its immune system may permit life-long immune tolerance of the transgenic protein, thus avoiding the dominant problem in haemophilia treatment, the formation of inhibitory antibodies.

METHODS

Adenovirus serotype 5-derived or AAV serotype 2-derived vectors carrying human clotting factor IX (hfIX) cDNA or a reporter gene were administered intramuscularly, intraperitoneally or intravascularly to late-gestation mouse fetuses. Both vector types were evaluated with respect to the kinetics of hfIX delivery to the systemic circulation and possible immune responses against the vector or the transgene product.

RESULTS

Mice treated in utero by intramuscular injection of an adenoviral vector carrying hfIX cDNA exhibited high-level gene expression at birth and therapeutic--albeit continuously decreasing--plasma concentrations of hfIX over the entire 6 months of the study. Adenoviral vector spread to multiple organs was detected by polymerase chain reaction (PCR). Intramuscular, intraperitoneal or intravascular application of AAV vectors carrying hfIX cDNA led to much lower plasma concentrations of hfIX shortly after birth, which appeared to decline during the first month of life but stabilized in some of the mice at detectable levels. No signs of immune responses were found, either against the different viral vectors or against hfIX.

CONCLUSION

This study demonstrates for the first time that sustained systemic delivery of a therapeutic protein can be achieved by prenatal gene transfer. It thus shows the feasibility of gene therapy in utero and provides a basis for considering this concept as a preventive therapeutic strategy for haemophilia and perhaps also for other plasma protein deficiencies.

NF-kappaB p50 is increased in neurons surviving hippocampal injury

Signal transduction pathways that lead to the modulation of genes related to survival and repair mechanisms are activated in neurons that survive injury. These protein kinase/phosphatase cascades converge on transcription factors, the DNA binding proteins that directly regulate gene expression. In this study we examined expression of the NF-kappaB p50 subunit in the rat hippocampus 7 days after injury caused by middle cerebral artery occlusion or trimethyltin treatment. We found increased levels of p50 in neurons throughout the hippocampus after both treatments, localized not only in cell bodies but also in processes. At the 7-day time point, Fluoro-Jade histochemistry revealed hippocampal neurodegeneration in trimethyltin-treated rats but not in those lesioned by middle cerebral artery occlusion. p50 was not expressed in Fluoro-Jade-positive degenerating cells, supporting the role of this transcriptional subunit in neurosurvival. Because phosphorylation of the inhibitor IkappaB protein by IkappaB kinase is the classic step in NF-kappaB activation, phospho-IkappaBalpha immunoreactivity was examined as an indication of IkappaB kinase activity. Levels of phospho-IkappaBalpha were increased in neurons throughout the hippocampus 7 days postinjury. Immunoblotting for phospho-IkappaBalpha demonstrated increased levels 1 day postinjury that remained elevated for at least 7 days. These data suggest that NF-kappaB signal transduction is involved in an adaptive response of neurons that survive injury.

Expression and activation of matrix metalloproteinase-2 and -9 in rat brain after transient focal cerebral ischemia

Matrix metalloproteinases (MMPs) degrade the extracellular matrix and carry out key functions during development and after injury. By means of zymography, Western blot and immunohistochemistry, we studied MMP-2 (gelatinase A) and MMP-9 (gelatinase B) in rat brain after focal cerebral ischemia. The control rat brain showed constitutive MMP-2 and, to a lesser extent, MMP-9, which were mainly present as prozymogens. MMP-2 protein was located in the cell body of neurons, glia, and endothelium, whereas MMP-9 was associated to neurons and myelinated fibre tracts. Ischemia greatly increased MMP activation in two temporal waves, in the first one, MMP-9 protein was induced from 4 h to 4 days, and also a small and short-lasting increase in MMP-2 was detected at 4 h. The second wave showed a massive increase in MMP-2 protein expression and activation by day 4, which was compatible with abundant MMP-2 in reactive microglia/macrophages. Our results are compatible with progressive induction of MMP-9 proform, likely in neurons, shortly after ischemia. For MMP-2, the results suggest a discrete production immediately after reperfusion, while a very enhanced expression and activation of MMP-2 attributable to microglia/macrophages occurs on day 4, and it might contribute to the phagocytic action of these reactive cells.

Nerve growth factor signaling, neuroprotection, and neural repair

Nerve growth factor (NGF) was discovered 50 years ago as a molecule that promoted the survival and differentiation of sensory and sympathetic neurons. Its roles in neural development have been characterized extensively, but recent findings point to an unexpected diversity of NGF actions and indicate that developmental effects are only one aspect of the biology of NGF. This article considers expanded roles for NGF that are associated with the dynamically regulated production of NGF and its receptors that begins in development, extends throughout adult life and aging, and involves a surprising variety of neurons, glia, and nonneural cells. Particular attention is given to a growing body of evidence that suggests that among other roles, endogenous NGF signaling subserves neuroprotective and repair functions. The analysis points to many interesting unanswered questions and to the potential for continuing research on NGF to substantially enhance our understanding of the mechanisms and treatment of neurological disorders.

Enhanced expression of I-kappaB with neurofibrillary pathology in Alzheimer's disease

Inflammatory and immune responses are known to be involved in the pathogenesis of Alzheimer's disease (AD). NF-kappaB is a major transcription factor that plays a central role in the inflammatory and immune responses and is regulated by I-kappaB through an autoregulatory feedback system. Southwestern immunohistochemistry and immunohistochemistry in our study demonstrated activated NF-kappaB in AD brains. However, there was also activated expression of I-kappaB in a distribution that corresponded to the neurofibrillary pathology of AD. These observations indicate that disruption of the autoregulatory mechanism of NF-kappaB in brain regions with neurofibrillary pathology may play a role in the pathogenesis of AD.

Effect of NF-kappa B Inhibition on TNF-alpha-induced apoptosis and downstream pathways in cardiomyocytes

Heart-specific inhibition of survival pathway gp130 was recently shown to sensitize transgenic mice towards stress stimuli, resulting in rapid onset of cardiac dilatation and heart failure. In order to identify further survival pathways we evaluated the role of transcription factor nuclear factor-kappa B (NF-kappa B) in tumour necrosis factor-alpha (TNF-alpha)-induced apoptosis of cardiomyocytes. TNF-alpha stimulation (10 ng/ml) of both H9c2 cells and primary cardiomyocytes isolated from neonatal Wistar rats resulted in rapid nuclear translocation of NF-kappa B complexes. The NF-kappa B complexes consisted of rel-proteins p50 and p65, as revealed by supershift analysis. Addition of proteasome inhibitor MG132 or adenoviral expression of a truncated I kappa B alpha (I kappa B Delta N) inhibited TNF-alpha-induced NF-kappa B nuclear translocation in a dose-dependent manner. Both neonatal cardiomyocytes and H9c2 cells were resistant to TNF-induced apoptosis. However, specific inhibition of NF-kappa B activation by Ad5-I kappa B alpha Delta N (MOI=50) or MG132 (5 microm) increased apoptosis as measured by subG1-assay (H9c2 cells) and annexin V binding/propidium iodide (neonatal cardiomyocytes, FACS-analysis: 7+/-2% to 26+/-5% annexin V positive/PI negative), respectively. TUNEL-assay double-stained with anti-alpha-sarcomeric actin confirmed apoptosis of neonatal cardiomyocytes. Furthermore, caspase-3 activation was increased by 52+/-7% in neonatal cardiomyocytes after TNF alpha+Ad5-I kappa B alpha Delta N compared to TNF alpha+Ad5-control treatment. Protein levels of hiAP1, hiAP2, x-iAP, bcl-2 and bcl-x(L) were neither downregulated by NF-kappa B inhibition nor upregulated by TNF-alpha stimulation. In summary, cardiomyocytes utilize transcription factor NF-kappa B to activate survival factors in the context of TNF-alpha stimulation. As locally increased levels of TNF-alpha have been detected in heart failure, NF-kappa B activity is essential for cellular homeostasis in the heart.