Selective gene expression and activation-dependent regulation of vasoactive intestinal peptide receptor type 1 and type 2 in human T cells

Vasoactive intestinal peptide (VIP) has potent antiproliferative and anti-inflammatory functions in the immune system. Two structurally distinct G-protein-associated receptors, VIP receptor type 1 (VPAC1) and VIP receptor type 2 (VPAC2), mediate the biological effects of VIP. The regulation of VIP receptor gene expression and the distribution of these receptors in different compartments of the human immune systems are unknown. This study reports, for the first time, a quantitative analysis of VPAC1 and VPAC2 mRNA expression in resting and activated T cells as well as in resting monocytes. Purified human peripheral blood CD4(+) T cells and CD8(+) T cells were stimulated via the TCR/CD3 receptor complex. Using the novel fluorometric-based kinetic (real-time) RT-PCR, we determined that VPAC1 is constitutively expressed in resting T cells and monocytes; the levels of expression were significantly higher in monocytes and CD4(+) T cells than in CD8(+) T cells. VPAC1 mRNA expression is significantly higher relative to VPAC2 in resting CD4(+) T cells and CD8(+) T cells. VPAC2 is expressed at very low levels in resting T cells but is not detectable in resting monocytes. In vitro stimulation of Th cells with soluble anti-CD3 plus PMA induced a T cell activation-dependent down-regulation of VPAC1. VPAC1 is down-regulated under conditions of optimal T cell stimulation. Our results suggest that selective VIP effects on T cell function may be mediated via selective expression of VPAC1 and VPAC2 on T cells and monocytes. Furthermore, down-regulation of VPAC1 in CD4(+) T cell subpopulations is highly correlated with T cell activation.

FGF-2, NGF and IGF-1, but not BDNF, utilize a nitric oxide pathway to signal neurotrophic and neuroprotective effects against alcohol toxicity in cerebellar granule cell cultures

Neuronal death is a prominent neuropathological component of fetal alcohol syndrome (FAS). Identification of molecular agents and pathways that can ameliorate alcohol-induced cell loss offers possible therapeutic strategies for FAS and potential insight into its pathogenesis. This study investigated the effects of growth factors on cellular survival in alcohol-exposed cerebellar granule cell (CGC) cultures and examined the role of the nitric oxide (NO)-cGMP-PKG (cGMP-dependent protein kinase) pathway in the cell survival-promoting effects of these growth factors. Primary CGC cultures were exposed to 0 or 400 mg/dl ethanol, accompanied by either no growth factor or 30 ng/ml fibroblast growth factor-2 (FGF-2), nerve growth factor (NGF), insulin-like growth factor-1 (IGF-1), brain-derived neurotrophic factor (BDNF) or epidermal growth factor (EGF). Viable neurons were quantified after 1 day of exposure. Two distinct types of cell survival-promoting effects of growth factors were detectable: (1) a neurotrophic effect, in which the growth factors diminished the background death of neurons that occurred in alcohol-free cultures; and (2) a neuroprotective effect, in which the growth factors diminished alcohol-induced cell death. The various growth factors differed markedly in their patterns of cell survival promotion. While BDNF and FGF-2 exerted both a neurotrophic and a neuroprotective effect, IGF-1 had only a neurotrophic effect and did not protect against alcohol toxicity, and NGF had only a neuroprotective effect and did not diminish background cell death. EGF had neither a neurotrophic nor a neuroprotective effect. In order to determine the role of the NO-cGMP-PKG pathway in the cell survival-promoting effects mediated by growth factors, cultures were exposed to one of several pharmacological inhibitors of the pathway, including NAME, LY83583 and PKG inhibitor. The cell survival-promoting effects of FGF-2, NGF and IGF-1 were all substantially reduced by each of the pathway inhibitors. In contrast, neither the neurotrophic nor the neuroprotective effects of BDNF were altered by any of the pathway inhibitors. Thus, growth factors differ in their patterns of neurotrophic and neuroprotective effects, and they differ in their reliance on the NO-cGMP-PKG pathway. While FGF-2, NGF and IGF-1 all signal their survival-promoting effects through the NO-cGMP-PKG pathway, BDNF does not rely upon this pathway for signal transduction in CGC cultures.

Use of frozen sections to determine neuronal number in the murine hippocampus and neocortex using the optical disector and optical fractionator

Stereology is an important technique for the quantification of neurons in subregions of the central nervous system. A commonly used method of stereology relies upon embedment of tissue in glycol methacrylates to allow production of sections that are resistant to shrinkage in thickness. However, the use of glycol methacrylates for stereology has several disadvantages, including severe constraints on the size of tissue that can be processed and the long duration of time often required for infiltration. We describe a novel method of stereology utilizing tissue sections cut in the frozen state. This new methodology relies upon the staining of sections as free-floating sections and upon the mounting of these sections onto slides with a water-based mounting media. Sections cut in the frozen state and processed by these methods undergo little or no shrinkage in thickness and are ideal for stereological cell counts utilizing either the optical disector or optical fractionator methods of stereology. We demonstrate that frozen sections can be utilized to estimate neuronal number with high degrees of precision and with low coefficients of error. Because large tissue blocks can be cut as frozen sections, this method expands the range of tissues that can be processed efficiently for stereology and readily allows quantification of neurons from multiple brain regions from the same tissue sections. We applied this new methodology to estimate neuronal numbers in the neocortex and hippocampus of 10-day-old mice. The method was useful for estimation of both large, sparsely packed cell populations, such as the neocortex, and small, densely packed cells, such as the dentate gyrus granule cells. Thus, frozen section methodology offers many potential advantages over the use of glycol methacrylate embedment for stereology. These advantages include expansion of the size of tissue blocks that can be processed, reduction in expended time and costs, and ability to quantify multiple brain regions from a single set of sections.

Congenital lymphocytic choriomeningitis virus infection: spectrum of disease

OBJECTIVE

Lymphocytic choriomeningitis virus (LCMV) is a human pathogen and an emerging neuroteratogen. When the infection occurs during pregnancy, the virus can target and damage the fetal brain and retina. We examined the spectrum of clinical presentations, neuroimaging findings, and clinical outcomes of children with congenital LCMV infection.

METHODS

Twenty children with serologically confirmed congenital LCMV infection were identified. The children underwent neuroimaging studies and were followed prospectively for up to 11 years.

RESULTS

All children with congenital LCMV infection had chorioretinitis and structural brain anomalies. However, the presenting clinical signs, severity of vision disturbance, nature and location of neuropathology, and character and severity of brain dysfunction varied substantially among cases. Neuroimaging abnormalities included microencephaly, periventricular calcifications, ventriculomegaly, pachygyria, cerebellar hypoplasia, porencephalic cysts, periventricular cysts, and hydrocephalus. The combination of microencephaly and periventricular calcifications was the most common neuroimaging abnormality, and all children with this combination had profound mental retardation, epilepsy, and cerebral palsy. However, others had less severe neuroimaging abnormalities and better outcomes. Some children had isolated cerebellar hypoplasia, with jitteriness as their presenting sign and ataxia as their principal long-term neurological dysfunction.

INTERPRETATION

Congenital LCMV infection can have diverse presenting signs, neuroimaging abnormalities, and clinical outcomes. In the companion article to this study, we utilize an animal model to show that the clinical and pathological diversity in congenital LCMV infection is likely due to differences in the gestational timing of infection.

Deficiency of neuronal nitric oxide synthase (nNOS) worsens alcohol-induced microencephaly and neuronal loss in developing mice

Previous work conducted in vitro suggests that nitric oxide (NO) protects developing neurons against the toxic effects of alcohol. We tested the hypothesis that neonatal mice carrying a null mutation for neuronal nitric oxide synthase (nNOS), the enzyme which synthesizes NO in neurons, have increased vulnerability to alcohol-induced microencephaly and neuronal loss. Wild-type mice and mutant (nNOS(-/-)) mice received a single intraperitoneal injection of ethanol (0.0, 2.2, 3.3, or 4.4 g/kg) daily over postnatal days (PD) 4-9 and were sacrificed on PD 10. Peak blood alcohol concentrations were approximately 170, 280, and 385 mg/dl for the 2.2, 3.3 and 4.4 g/kg/day treatment groups, respectively, and did not differ significantly between wild-type and nNOS(-/-) strains. Exposure to alcohol induced dose-dependent reductions in total brain weight, forebrain weight and cerebellum weight in both strains of mice. However, the reductions in brain weight were significantly more severe in the nNOS(-/-) mice than in wild type. Quantification of cerebellar neurons revealed that alcohol-induced losses of Purkinje cells and granule cells were both significantly greater in the nNOS(-/-) mice than in wild type. The increased vulnerability of nNOS-deficient neurons to alcohol-induced cell death was confirmed in vitro. Cerebellar granule cell cultures derived from nNOS(-/-) and wild-type mice were exposed for 24 h to 0, 100, 200 or 400 mg/dl ethanol. At each alcohol concentration, the nNOS(-/-) neurons had a significantly greater cell loss than did the wild-type neurons. The results demonstrate that deficiency of nNOS decreases the ability of developing neurons to survive the toxic effects of alcohol. Because NO upregulates intracellular cGMP, which can activate cGMP-dependent protein kinase (PKG), we hypothesize that the NO-cGMP-PKG pathway has a neuroprotective role against alcohol toxicity within the developing brain.

Histone deacetylase inhibitors modulate renal cell carcinoma sensitivity to TRAIL/Apo-2L-induced apoptosis by enhancing TRAIL-R2 expression

Every year, 12,000 people in the U.S. die from renal cell carcinoma. Current therapies include partial or complete nephrectomy or treatments such as administration of IFN-alpha and/or interleukins that are moderately effective, at best. Moreover, the current therapies are invasive and inefficient and new therapies are needed. Histone deacetylase (HDAC) inhibitors have recently been found to sensitize cells to apoptosis-inducing agents, although the mechanism of this action is largely unknown. The current study has investigated the potential of using five different histone deacetylase inhibitors (HDACI) (depsipeptide, MS-275, oxamflatin, sodium butyrate, and trichostatin A) to sensitize TNF-related apoptosis-inducing ligand (TRAIL)/Apo-2L-resistant renal cell carcinoma cells to TRAIL/Apo-2L-induced apoptosis. Sodium butyrate and trichostatin A each enhanced TRAIL/Apo-2L-mediated tumor cell death to a greater extent than the other HDACI. Annexin V staining and caspase activity demonstrated the mechanism of cell death was apoptosis. Both sodium butyrate and trichostatin A treatment also increased mRNA and surface expression of TRAIL receptor 2 that was dependent on the transcription factor Sp1, thus providing a possible mechanism behind the increased sensitivity to TRAIL/Apo-2L. These results indicate that combination therapy of HDACI, such as sodium butyrate and trichostatin A, and TRAIL/Apo-2L has great potential for an efficient alternative therapy for renal cell carcinoma.

Inhibition of the NF-κB pathway enhances TRAIL-mediated apoptosis in neuroblastoma cells

Neuroblastoma is the most common solid extracranial neoplasm in children and causes many deaths. Despite treatment advances, prognosis for neuroblastoma remains poor, and a critical need exists for the development of new treatment regimens. TNF-related apoptosis-inducing-ligand (TRAIL) induces cell death in a variety of tumors, but not in normal tissues. Moreover, TRAIL is nontoxic, making it a strong antitumor therapeutic candidate. We demonstrate that introduction of the TRAIL gene into neuroblastoma cell lines using an adenoviral vector leads to apoptotic cell death. RT-PCR and flow-cytometric analyses demonstrated that TRAIL's effect is mediated primarily via the TRAIL R2 receptor. As TRAIL can activate the nuclear factor-kappaB (NF-kappaB) signaling pathway, which can exert an antiapoptotic effect, we hypothesized that inhibition of NF-kappaB signaling may augment TRAIL's killing effects. TRAIL-mediated cell death was enhanced when neuroblastoma cells were simultaneously infected with a dominant-negative mutant of IkappaB kinase, a kinase essential for NF-kappaB activation. The combination of blockade of NF-kappaB signaling and expression of TRAIL induced apoptotic death in a greater proportion of SKNSH cells than did either treatment alone. Thus, concurrent inhibition of the NF-kappaB pathway and the induction of TRAIL-mediated apoptosis may become a useful approach for the treatment of neuroblastoma.

Critical role for glial cells in the propagation and spread of lymphocytic choriomeningitis virus in the developing rat brain

Inoculation of the neonatal rat with lymphocytic choriomeningitis virus (LCMV) results in the selective infection of several neuronal populations and in focal pathological changes. However, the pathway by which LCMV reaches the susceptible neurons has not been described, and the nature and time course of the pathological changes induced by the infection are largely unknown. This study examined the sequential migration of LCMV in the developing rat brain and compared the pathological changes among infected brain regions. The results demonstrate that astrocytes and Bergmann glia cells are the first cells of the brain parenchyma infected with LCMV and that the virus spreads across the brain principally via contiguous glial cells. The virus then spreads from glial cells into neurons. However, not all neurons are susceptible to infection. LCMV infects neurons in only four specific brain regions: the cerebellum, olfactory bulb, dentate gyrus, and periventricular region. The virus is then cleared from glial cells but persists in neurons. LCMV induces markedly different pathological changes in each of the four infected regions. The cerebellum undergoes an acute and permanent destruction, while the olfactory bulb is acutely hypoplastic but recovers fully with age. Neurons of the dentate gyrus are unaffected in the acute phase but undergo a delayed-onset mortality. In contrast, the periventricular region has neither acute nor late-onset cell loss. Thus, LCMV infects four specific brain regions in the developing brain by spreading from glial cells to neurons and then induces substantially different pathological changes with diverse time courses in each of the four infected regions.

Therapeutic potential of VIP vs PACAP in diabetes

Type 2 diabetes (T2D) is characterized by chronic insulin resistance and a progressive decline in beta-cell function. Although rigorous glucose control can reduce morbidity and mortality associated with diabetes, achieving optimal long-term glycemic control remains to be accomplished in many diabetic patients. As beta-cell mass and function inevitably decline in T2D, exogenous insulin administration is almost unavoidable as a final outcome despite the use of oral antihyperglycemic agents in many diabetic patients. Pancreatic islet cell death, but not the defect in new islet formation or beta-cell replication, has been blamed for the decrease in beta-cell mass observed in T2D patients. Thus, therapeutic approaches designed to protect islet cells from apoptosis could significantly improve the management of T2D, because of its potential to reverse diabetes not just ameliorate glycemia. Therefore, an ideal beta-cell-preserving agent is expected to protect beta cells from apoptosis and stimulate postprandial insulin secretion along with increasing beta-cell replication and/or islet neogenesis. One such potential agent, the islet endocrine neuropeptide vasoactive intestinal peptide (VIP) strongly stimulates postprandial insulin secretion. Because of its broad spectrum of biological functions such as acting as a potent anti-inflammatory factor through suppression of Th1 immune response, and induction of immune tolerance via regulatory T cells, VIP has emerged as a promising therapeutic agent for the treatment of many autoimmune diseases including diabetes.

Adenovirus-mediated IKKβKA expression sensitizes prostate carcinoma cells to TRAIL-induced apoptosis

Despite the fact that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can selectively induce apoptosis in cancer cells, TRAIL resistance in cancer cells has challenged the use of TRAIL as a therapeutic agent. First, prostate carcinoma cell lines (DU145, LNCaP and PC3) were screened for sensitivity to adenovirus delivery of TRAIL (Ad5hTRAIL). As amplified Ikappa B kinase (IKK) activity is responsible for the constitutive nuclear factor-kappaB (NF-kappaB) activation leading to uncontrolled cell growth and metastasis, a dual vector approach using both an adenovirus vector (Ad) expressing the dominant-negative mutant of IKKbeta (AdIKKbetaKA) and Ad5hTRAIL was employed to determine if prostate cancer cells were sensitized to TRAIL in the setting of IKK inhibition. Inhibition of the NF-kappaB pathway through IKK blockade sensitized all three prostate cancer cell lines to TRAIL, regardless of NF-kappaB activation or decoy receptor gene expression. Moreover, a novel quantitative real-time RT-PCR assay and conventional flow cytometry analysis indicated that TRAIL-resistant DU145 and LNCaP cells, but not TRAIL-sensitive PC3 cells, expressed substantial amounts of TRAIL Decoy Receptor 4. In conclusion, TRAIL decoy receptor expression appeared to be the chief determinant of TRAIL resistance encountered in prostate carcinoma cell lines.

Lymphocytic choriomeningitis virus infection of the developing brain: critical role of host age

OBJECTIVE

Lymphocytic choriomeningitis virus (LCMV) is a common human pathogen that causes substantial injury to the developing brain when the infection occurs during pregnancy. However, among children with congenital LCMV infection, there is considerable variability in the site, nature, and severity of neuropathology and in the clinical outcome. We hypothesize that the variability in neuropathology and outcome is due to differences in the gestational timing of LCMV infection.

METHODS

We utilized an animal model of human congenital LCMV infection, in which developing rat pups were inoculated with LCMV at a series of postnatal ages, including postnatal days 1, 4, 6, 10, 21, 30, and 60. Cellular targets of infection were determined immunohistochemically, viral titers were determined by plaque assay, and pathology was determined by histological analysis, neuronal quantification, and immunostaining for lymphocytic subclasses.

RESULTS

Host age at the time of infection profoundly affected the cellular targets of infection, maximal viral titers, immune response to the viral infection, and the severity, nature, and location of the neuropathology. All of the pathological changes observed in children with congenital LCMV infection were reproduced in the rat model by infecting the rat pups at different ages.

INTERPRETATION

The effect of LCMV infection on the developing brain strongly depends on host age at the time of infection. Much of the variability in neuropathology and outcome among children with congenital LCMV infection probably depends on the gestational age at which the infection occurs.

The protective effect of neuronal nitric oxide synthase (nNOS) against alcohol toxicity depends upon the NO-cGMP-PKG pathway and NF-kappaB

Fetal alcohol syndrome (FAS) stems from maternal alcohol abuse during pregnancy and is an important cause of mental retardation and hyperactivity in children. In the developing brain, alcohol can kill neurons, leading to microencephaly. However, due to their genetic makeup, some individuals are less vulnerable than others to alcohol's neurotoxic effects. Animal studies have demonstrated that one particular gene, neuronal nitric oxide synthase (nNOS), protects developing neurons in vivo against alcohol-induced death. We utilized pharmacologic techniques to demonstrate that nNOS protects neurons against alcohol toxicity by activating the NO-cGMP-PKG signaling pathway. Cerebellar granule cell cultures derived from mice carrying a null mutation for nNOS (nNOS-/- mice) were substantially more vulnerable than cultures from wild-type mice to alcohol-induced cell death. However, activation of the pathway at sites downstream of nNOS protected the cultures against alcohol toxicity. Conversely, blockade of the pathway rendered wild-type cultures vulnerable to alcohol-induced death. We further identified NF-kappaB as the downstream effector through which nNOS and the NO-cGMP-PKG pathway signal their neuroprotective effects. Tumor necrosis factor-alpha (TNF-alpha), which activates NF-kappaB, ameliorated alcohol-induced cell death in nNOS-/- and wild-type cultures, while an NF-kappaB inhibitor (NFi) blocked the protective effects of TNF-alpha and worsened alcohol-induced cell death. Furthermore, NFi blocked the protective effects of NO-cGMP-PKG pathway activators, demonstrating that NF-kappaB is downstream of the NO-cGMP-PKG pathway. As wild-type neurons matured in culture, they became resistant to alcohol toxicity. However, this maturation-dependent alcohol resistance did not occur in nNOS-/- mice and could be reversed in wild-type mice with NFi, demonstrating that nitric oxide and NF-kappaB are crucial for the development of alcohol resistance with age. Thus, nNOS protects developing neurons against alcohol toxicity by activating the NO-cGMP-PKG-NF-kappaB pathway and is crucial for the acquisition of maturation-dependent alcohol resistance.

DcR2 (TRAIL-R4) siRNA and adenovirus delivery of TRAIL (Ad5hTRAIL) break down in vitro tumorigenic potential of prostate carcinoma cells

High levels of decoy receptor 2 (DcR2; TRAIL-R4) expression are correlated with TRAIL resistance in prostate cancer cells. In addition, upregulation of TRAIL death receptor (DR4 and DR5) expression, either by ionizing radiation or chemotherapy, can sensitize cancer cells to TRAIL. Considering more than half of human cancers are TRAIL resistant, modulation of surface TRAIL receptor expression appears to be an attractive treatment modality to counteract TRAIL resistance. In this study, three siRNA duplexes targeting DcR2 receptor were tested. Ad5hTRAIL infections were performed to overexpress human full-length TRAIL to induce cell death, and the in vitro tumorigenic potential of prostate cancer cells was assessed using colony-forming assays on soft agar. The DU145 and LNCaP prostate cancer cell lines, which express high levels of DcR2, were resistant to Ad5hTRAIL-induced death. Downregulation of surface DcR2 expression by siRNA sensitized these prostate cancer cell lines to Ad5hTRAIL. In addition, DcR2 siRNA-mediated knockdown of DcR2, followed by Ad5hTRAIL infection, dramatically reduced the in vitro tumorigenic potential of prostate cancer cells. Collectively, our results suggest the potential for combining receptor-specific siRNA with TRAIL in the treatment of certain cancers.

A single exposure to alcohol during brain development induces microencephaly and neuronal losses in genetically susceptible mice, but not in wild type mice

Maternal alcohol abuse during pregnancy can damage the fetal brain and lead to fetal alcohol syndrome (FAS). Despite public warnings discouraging alcohol use during pregnancy, many pregnant women continue to drink intermittently because they do not believe that occasional exposures to alcohol can be harmful to a fetus. However, because of genetic differences, some fetuses are much more susceptible than others to alcohol-induced brain injury. Thus, a relatively low quantity of alcohol that may be innocuous to most fetuses could damage a genetically susceptible fetus. Neuronal nitric oxide synthase (nNOS) can protect developing mouse neurons against alcohol toxicity by synthesizing neuroprotective nitric oxide. This study examined whether a single exposure to alcohol, which causes no evident injury in wild type mice, can damage the brains of mice genetically deficient for nNOS (nNOS-/- mice). Wild type and nNOS-/- mice received intraperitoneal injections of alcohol (0.0, 2.2, or 4.4mg/g body weight) either as a single dose on postnatal day (PD) 4 or as repeated daily doses over PD4-9. Brain volumes and neuronal numbers within the hippocampus and cerebral cortex were determined on PD10. Alcohol exposure on PD4-9 restricted brain growth and caused neuronal death in both strains of mice, but the severity of microencephaly and neuronal loss were more severe in the nNOS-/- mice than in wild type. The 4.4 mg/g alcohol dose administered on PD4 alone caused significant neuronal loss and microencephaly in the nNOS-/- mice, while this same dose caused no evident injury in the wild type mice. Thus, during development, a single exposure to alcohol can injure a genetically vulnerable brain, while it leaves a wild type brain unaffected. Since the genes that confer alcohol resistance and vulnerability in developing humans are unknown, any particular human fetus is potentially vulnerable. Thus, women should be counseled to consume no alcohol during pregnancy.

Decoy Receptor-2 Small Interfering RNA (siRNA) Strategy Employing Three Different siRNA Constructs in Combination Defeats Adenovirus-Transferred Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand Resistance in Lung Cancer Cells

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) selectively induces apoptosis in cancer cells but not in normal cells. However, studies have indicated that more than half of human tumors exhibit TRAIL resistance. Although the mechanism of TRAIL resistance is not understood, it represents a barrier to any TRAIL-mediated gene therapy approach. In addition, no correlation between TRAIL receptor (TRAIL-R) expression profile and TRAIL resistance has been demonstrated in cancer cells. In this study, three different lung cancer cell lines and three different primary cell cultures established from patients with lung cancer (two patients with squamous cell lung carcinoma and one with adenocarcinoma) were screened for sensitivity to adenoviral delivery of TRAIL. Whereas TRAIL-resistant primary lung cell cultures and the A549 lung cancer cell line exhibited high levels of surface decoy receptor-2 (DcR2/TRAIL-R4) expression, TRAIL-sensitive lung cancer cell lines (HBE and H411) failed to express it. A DcR2 short interfering RNA (siRNA) approach involving three different siRNA constructs in combination downregulated DcR2/TRAIL-R4 expression and sensitized lung cancer cells to TRAIL-induced apoptosis. Immunohistochemical staining of samples from 10 patients with lung carcinoma suggested that high-level DcR2/TRAIL-R4 expression is a common phenotype observed in patients with non-small cell lung carcinoma.

Importance of genetics in fetal alcohol effects: null mutation of the nNOS gene worsens alcohol-induced cerebellar neuronal losses and behavioral deficits

The cerebellum is a major target of alcohol-induced damage in the developing brain. However, the cerebella of some children are much more seriously affected than others by prenatal alcohol exposure. As a consequence of in utero alcohol exposure, some children have substantial reductions in cerebellar volume and corresponding neurodevelopmental problems, including microencephaly, ataxia, and balance deficits, while other children who were exposed to similar alcohol quantities are spared. One factor that likely plays a key role in determining the impact of alcohol on the fetal cerebellum is genetics. However, no specific gene variant has yet been identified that worsens cerebellar function as a consequence of developmental alcohol exposure. Previous studies have revealed that mice carrying a homozygous mutation of the gene for neuronal nitric oxide synthase (nNOS-/- mice) have more severe acute alcohol-induced neuronal losses from the cerebellum than wild type mice. Therefore, the goals of this study were to determine whether alcohol induces more severe cerebellum-based behavioral deficits in nNOS-/- mice than in wild type mice and to determine whether these worsened behavior deficits are associated with worsened cerebellar neuronal losses. nNOS-/- mice and their wild type controls received alcohol (0.0, 2.2, or 4.4mg/g) daily over postnatal days 4-9. In adulthood, the mice underwent behavioral testing, followed by neuronal quantification. Alcohol caused dose-related deficits in rotarod and balance beam performance in both nNOS-/- and wild type mice. However, the alcohol-induced behavioral deficits were substantially worse in the nNOS-/- mice than in wild type. Likewise, alcohol exposure led to losses of Purkinje cells and cerebellar granule cells in mice of both genotypes, but the cell losses were more severe in the nNOS-/- mice than in wild type. Behavioral performances were correlated with neuronal number in the nNOS-/- mice, but not in wild type. Thus, homozygous mutation of the nNOS gene increases vulnerability to alcohol-induced cerebellar dysfunction and neuronal loss. nNOS is the first gene identified whose mutation worsens alcohol-induced cerebellar behavioral deficits.

The NO-cGMP-PKG pathway plays an essential role in the acquisition of ethanol resistance by cerebellar granule neurons

When the developing brain is exposed to alcohol, neuronal death is a prominent pathologic effect. This loss of neurons may underlie many of the behavioral deficits observed in fetal alcohol syndrome (FAS). Previous studies using whole animals and cultured neurons have demonstrated that the vulnerability of neurons to alcohol-induced death changes with development and can diminish markedly over the course of several days. This study examined the possibility that developmental stage-dependent alcohol resistance depends on a unique signaling pathway involving nitric oxide (NO), the NO-cyclic GMP (cGMP)-cGMP-dependent protein kinase (PKG) pathway. Cerebellar granule neuron (CGN) cultures were established from neonatal rats. The cultures were exposed to alcohol (400 mg/dl) either when they were newly established (1 day in vitro, 1-DIV) or when they were more mature (4 days in vitro, 4-DIV). Viable neurons were quantified 24 h later. Although both 1-DIV and 4-DIV cultures were exposed to alcohol for an identical length of time (24 h), the 1-DIV cultures were much more vulnerable to alcohol-induced neuronal death (22.9% neuronal loss) than the 4-DIV cultures (2.3% neuronal loss). Thus, the cultures have a developmental stage-dependent alcohol resistance. To determine the role of the NO-cGMP-PKG pathway in this developmental stage-dependent alcohol resistance, the CGN cultures at 4-DIV were exposed to agents that either activated or inhibited the pathway, either in the presence or in the absence of alcohol. Inhibition of the pathway at its first step with N(G)-nitro-l-arginine-methyl ester (NAME) or at its second step with LY83583 converted the 4-DIV cultures from alcohol resistant to alcohol sensitive. Alcohol-induced neuronal losses were as severe in the 4-DIV cultures treated with pathway inhibitors as they were in the 1-DIV cultures. Treatment of the CGN cultures with agents that activate the NO-cGMP-PKG pathway reduced background cell death, and this neurotrophic effect was not inhibited by the presence of alcohol. Furthermore, activation of the NO-cGMP-PKG pathway at sites downstream from sites of pathway inhibition restored alcohol resistance. Thus, the developmental stage-dependent alcohol resistance acquired by CGN cultures depends on a functional NO-cGMP-PKG pathway.

Caspase 8L, a novel inhibitory isoform of caspase 8, is associated with undifferentiated neuroblastoma

Caspase 8 is a key apoptotic factor in the receptor/ligand apoptosis-signaling cascade. Absent caspase 8 expression is shown to correlate with poor prognosis in neuroblastoma. Paradoxically, the caspase 8 gene can produce as plice variant and novel inhibitor of itself-caspase 8l. The presence of caspase 8 alone in tumors may not necessarily portend a good prognosis. We sought to determine whether caspase 8l is present in neuroblastoma and whether over-expression of this protein could inhibit caspase 8-dependent apoptosis. Six of 6 histologically undifferentiated and 2 of 5 differentiated neuroblastoma tumors expressed the caspase 8l isoform, whereas caspase 8l was absent in 3 of 3 ganglioneuromas. Seven human neuroblastoma cell lines were surveyed. Two of the 5 cell lines that expressed caspase 8 also expressed the caspase 8l isoform and both were of a less differentiated neuronal phenotype. Over-expression of caspase 8l in cell lines afforded protection against TRAIL, but not against etoposide induced apoptosis. Conversely, blockade of Caspase 8l in cells that express this splice variant made them more sensitive to apoptosis induced cell death. We demonstrate the caspase 8l isoform is present in neuroblastoma and appears to be associated with undifferentiated cell lines and tumors. Furthermore, it suppresses caspase 8-dependent apoptosis.

Severe alcohol-induced neuronal deficits in the hippocampus and neocortex of neonatal mice genetically deficient for neuronal nitric oxide synthase (nNOS)

Alcohol can severely damage the developing brain, and neuronal loss is a critical component of this injury. Thus, identification of molecular factors that ameliorate alcohol-induced neuronal loss is of great importance. Previous in vitro work has demonstrated that nitric oxide (NO) protects neurons against alcohol toxicity. We tested the hypothesis that neonatal mice carrying a null mutation for neuronal nitric oxide synthase (nNOS), the enzyme that synthesizes NO in neurons, have an increased vulnerability to alcohol-induced neuronal loss in the neocortex and hippocampus. Wildtype mice and nNOS-/- mice received ethanol (0.0, 2.2, 3.3, or 4.4 g/kg) daily over postnatal days (P) 4-9 and were sacrificed on P10. The number of hippocampal CA1 and CA3 pyramidal cells, dentate gyrus granule cells, and neocortical neurons were determined using stereological methods. Alcohol pharmacokinetics did not differ between wildtype and nNOS-/- strains. Alcohol induced dose-dependent reductions in all four neuronal populations, and the losses were substantially more severe in the nNOS-/- mice than in wildtype. Furthermore, the threshold dose of alcohol to induce cell death was lower in the nNOS-/- mice than in the wildtype mice for all neuronal populations. While nNOS deficiency worsened alcohol-induced neuronal losses, the magnitude of this exacerbation varied among brain regions and depended on alcohol dose. These results demonstrate that nNOS deficiency decreases the ability of developing neurons in vivo to survive the toxic effects of alcohol and strengthen the hypothesis that NO exerts a neuroprotective effect against alcohol toxicity in the developing brain.

Sydenham's chorea: not gone and not forgotten

Sydenham's chorea is an ancient disease that continues to afflict large numbers of children throughout the world. A major manifestation of rheumatic fever, Sydenham's chorea is commonly manifested by movement disorder and psychiatric problems, and also may be a marker for a life-threatening carditis. Because Sydenham's chorea is triggered by streptococcal pharyngitis, the most important component of its therapy is antibiotic prophylaxis against further streptococcal infections. Because the pathogenesis of Sydenham's chorea includes the production of anti-basal ganglia antibodies, therapies that modulate immune function or that restore neurotransmitter balance within the basal ganglia may be effective for Sydenham's chorea. Recent reports have suggested that Sydenham's chorea may be part of a spectrum of neuropsychiatric syndromes induced by streptococcal infection.

Meningitis and encephalitis in children. An update

Over the course of the past decade, much has changed on the landscape of meningitis and encephalitis in children. West Nile virus has emerged in the United States as a new etiologic pathogen causing encephalitis. Human herpesvirus-6 has been identified as a cause of encephalitis and febrile seizures. Lymphocytic choriomeningitis virus has been identified as an underrecognized neuroteratogen. The emergence of penicillin-resistant Streptococcus pneumoniae has complicated the treatment of bacterial meningitis, whereas the Haemophilus influenzae vaccine has fundamentally altered the disease's epidemiology. The recognition that much of the neuropathologic change induced by bacterial meningitis is inflammation mediated has paved the way to the demonstration that dexamethasone can substantially improve the outcome of bacterial meningitis in children. Although much progress has been made toward understanding, treating, and preventing these important infections, much remains to be learned.

NF-κB targeting by way of IKK inhibition sensitizes lung cancer cells to adenovirus delivery of TRAIL

Background

Lung cancer causes the highest rate of cancer-related deaths both in men and women. As many current treatment modalities are inadequate in increasing patient survival, new therapeutic strategies are required. TNF-related apoptosis-inducing ligand (TRAIL) selectively induces apoptosis in tumor cells but not in normal cells, prompting its current evaluation in a number of clinical trials. The successful therapeutic employment of TRAIL is restricted by the fact that many tumor cells are resistant to TRAIL. The goal of the present study was to test a novel combinatorial gene therapy modality involving adenoviral delivery of TRAIL (Ad5hTRAIL) and IKK inhibition (AdIKKβKA) to overcome TRAIL resistance in lung cancer cells.

Methods

Fluorescent microscopy and flow cytometry were used to detect optimum doses of adenovirus vectors to transduce lung cancer cells. Cell viability was assessed via a live/dead cell viability assay. Luciferase assays were employed to monitor cellular NF-κB activity. Apoptosis was confirmed using Annexin V binding.

Results

Neither Ad5hTRAIL nor AdIKKβKA infection alone induced apoptosis in A549 lung cancer cells, but the combined use of Ad5hTRAIL and AdIKKβKA significantly increased the amount of A549 apoptosis. Luciferase assays demonstrated that both endogenous and TRAIL-induced NF-κB activity was down-regulated by AdIKKβKA expression.

Conclusions

Combination treatment with Ad5hTRAIL and AdIKKβKA induced significant apoptosis of TRAIL-resistant A549 cells, suggesting that dual gene therapy strategy involving exogenous TRAIL gene expression with concurrent IKK inhibition may be a promising novel gene therapy modality to treat lung cancer.

Genetic absence of nNOS worsens fetal alcohol effects in mice. II: microencephaly and neuronal losses

BACKGROUND

Prenatal alcohol exposure can kill developing neurons, leading to microencephaly and mental retardation. However, not all fetuses are equally vulnerable to alcohol's neurotoxic effects. While some fetuses are severely affected and are ultimately diagnosed with fetal alcohol syndrome (FAS), others have no evidence of neuropathology and are behaviorally normal. These widely different outcomes among alcohol-exposed fetuses are likely due, in part, to genetic differences. Some fetuses possess genotypes that make them much more vulnerable than others to alcohol's teratogenic effects. However, to date, only 1 gene has been identified whose mutation can worsen alcohol-induced behavioral deficits in an animal model of FAS. That gene is neuronal nitric oxide synthase (nNOS). The purpose of this study was to determine whether mutation of nNOS can likewise worsen alcohol-induced microencephaly and lead to permanent neuronal deficits.

METHODS

Wild-type and nNOS(-/-) mice received alcohol (0.0, 2.2, or 4.4 mg/g) daily over postnatal days (PDs) 4 to 9. Beginning on PD 85, the mice underwent a series of behavioral tests; the results of which are reported in the companion paper. The brains were then weighed, and stereological cell counts were performed on the cerebral cortex and hippocampal formation, which are the brain regions that mediate the aforementioned behavioral tasks.

RESULTS

Alcohol caused dose-dependent microencephaly, but only in the nNOS(-/-) mice and not in wild-type mice. Alcohol-induced neuronal losses were more severe in the nNOS(-/-) mice than in the wild-type mice in all of the brain regions examined, including the cerebral cortex, hippocampal CA3 subregion, hippocampal CA1 subregion, and dentate gyrus.

CONCLUSIONS

Targeted mutation of the nNOS gene increases the vulnerability of the developing brain to alcohol-induced growth restriction and neuronal losses. This increased neuropathology is associated with worsened behavioral dysfunction. The results demonstrate the critical importance of genotype in determining the outcome of developmental alcohol exposure.

Vasoactive intestinal peptide (VIP) receptor type 2 (VPAC2) is the predominant receptor expressed in human thymocytes

Vasoactive intestinal peptide (VIP) binding sites have been identified in the human thymus, but the receptor subtype and how these receptors are distributed in the human thymus subsets is unknown. To assess gene expression, distribution, and receptor regulation of the two G-protein-associated VIP receptors, VPAC1 and VPAC2 mRNAs were quantified using a novel fluorometric-based kinetic (real-time) RT-PCR. Bulk and fractionated thymocytes were stimulated via the TCR/CD3 receptor complex and anti-CD28. Our results demonstrate that thymocytes express higher levels of VPAC2 compared to VPAC1 expression in bulk thymocytes, CD4+CD8+ selected double positives (DP), and CD8 depleted thymocytes. Double negative cells express low levels of VPAC2 mRNA. We demonstrate T-cell activation-dependent down-regulation of VPAC1, but not VPAC2, in human thymocytes. This study reports the first direct evidence of a differential distribution and selective regulation of VPAC1 and VPAC2 gene expression in normal human thymocyte subsets.