Derivation, validation, and transcriptomic assessment of pediatric septic shock phenotypes identified through latent profile analyses: Results from a prospective multi-center observational cohort

Background

Sepsis poses a grave threat, especially among children, but treatments are limited due to clinical and biological heterogeneity among patients. Thus, there is an urgent need for precise subclassification of patients to guide therapeutic interventions.

Methods

We used clinical, laboratory, and biomarker data from a prospective multi-center pediatric septic shock cohort to derive phenotypes using latent profile analyses. Thereafter, we trained a support vector machine model to assign phenotypes in a hold-out validation set. We tested interactions between phenotypes and common sepsis therapies on clinical outcomes and conducted transcriptomic analyses to better understand the phenotype-specific biology. Finally, we compared whether newly identified phenotypes overlapped with established gene-expression endotypes and tested the utility of an integrated subclassification scheme.

Findings

Among 1,071 patients included, we identified two phenotypes which we named 'inflamed' (19.5%) and an 'uninflamed' phenotype (80.5%). The 'inflamed' phenotype had an over 4-fold risk of 28-day mortality relative to those 'uninflamed'. Transcriptomic analysis revealed overexpression of genes implicated in the innate immune response and suggested an overabundance of developing neutrophils, pro-T/NK cells, and NK cells among those 'inflamed'. There was no significant overlap between endotypes and phenotypes. However, an integrated subclassification scheme demonstrated varying survival probabilities when comparing endophenotypes.

Interpretation

Our research underscores the reproducibility of latent profile analyses to identify clinical and biologically informative pediatric septic shock phenotypes with high prognostic relevance. Pending validation, an integrated subclassification scheme, reflective of the different facets of the host response, holds promise to inform targeted intervention among those critically ill.

Ceftriaxone Pharmacokinetics and Pharmacodynamics in 2 Pediatric Patients on Extracorporeal Membrane Oxygenation Therapy

BACKGROUND

Critically ill patients with cardiac or respiratory failure may require extracorporeal membrane oxygenation (ECMO). Antibiotics are frequently administered when the suspected cause of organ failure is an infection. Ceftriaxone, a β-lactam antibiotic, is commonly used in patients who are critically ill. Although studies in adults on ECMO have suggested minimal impact on ceftriaxone pharmacokinetics, limited research exists on ceftriaxone pharmacokinetics/pharmacodynamics (PK/PD) in pediatric ECMO patients. We report the PK profiles and target attainment of 2 pediatric patients on ECMO who received ceftriaxone.

METHODS

Ceftriaxone concentrations were measured in 2 pediatric patients on ECMO using scavenged opportunistic sampling. PK profiles were generated and individual PK parameters were estimated using measured free ceftriaxone concentrations and a published population PK model in children who are critically ill, using Bayesian estimation.

RESULTS

Patient 1, an 11-year-old boy on venovenous ECMO for respiratory failure received 2 doses of 52 mg/kg ceftriaxone 12 hours apart while on ECMO and additional doses every 12 hours off ECMO. On ECMO, ceftriaxone clearance was 13.0 L/h/70 kg compared with 7.6 L/h/70 kg off ECMO, whereas the model-predicted mean clearance in children who are critically ill without ECMO support was 6.54 L/h/70 kg. Patient 2, a 2-year-old boy on venoarterial ECMO due to cardiac arrest received 50 mg/kg ceftriaxone every 12 hours while on ECMO for >7 days. Only clearance while on ECMO could be estimated (9.1 L/h/70 kg). Trough concentrations in both patients were >1 mg/L (the breakpoint for Streptococcus pneumoniae ) while on ECMO.

CONCLUSIONS

ECMO increased ceftriaxone clearance above the model-predicted clearances in the 2 pediatric patients studied. Twelve-hour dosing allowed concentrations to remain above the breakpoint for commonly targeted bacteria but not 4 times the breakpoint in one patient, suggesting that precision dosing may be beneficial to ensure target attainment in children on ECMO.

Obesity Alters cytokine signaling and gut microbiome in septic mice

Sepsis is a leading cause of mortality. Plasma cytokine levels may identify those at increased risk of mortality from sepsis. Our aim was to understand how obesity alters cytokine levels during early sepsis and its correlation with survival. Six-week-old C57BL/6 male mice were randomized to control (non-obese) or high fat diet (obese) for 5-7 weeks. Sepsis was induced by cecal ligation and perforation (CLP). Cytokine levels were measured from cheek bleeds 8 h after CLP, and mice were monitored for survival. Other cohorts were sacrificed 1 h after CLP for plasma and tissue. Septic obese mice had higher survival. At 8 h after sepsis, obese mice had higher adiponectin, leptin, and resistin but lower TNFα and IL-6 compared to non-obese mice. When stratified by 24-h survival, adipokines were not significantly different in obese and non-obese mice. TNFα and IL-6 were higher in non-obese, compared to obese, mice that died within 24 h of sepsis. Diet and to sepsis significantly impacted the cecal microbiome. IL-6 is a prognostic biomarker during early sepsis in non-obese and obese mice. A plausible mechanism for the survival difference in non-obese and obese mice may be the difference in gut microbiome and its evolution during sepsis.

OBESE MICE WITH PNEUMONIA HAVE HYPERLEPTINEMIA AND INCREASED PULMONARY SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION 3 ACTIVATION

ABSTRACT

Obesity is an ongoing epidemic that influences pathobiology in numerous disease states. Obesity is associated with increased plasma leptin levels, a hormone that activates the signal transducer and activator of transcription 3 (STAT3) pathway. Pneumonia is a significant cause of morbidity and mortality. During pneumonia, inflammatory pathways including STAT3 are activated. Outcomes in obese patients with pneumonia are mixed, with some studies showing obesity increases harm and others showing benefit. It is unclear whether obesity alters STAT3 activation during bacterial pneumonia and how this might impact outcomes from pneumonia. We used a murine model of obesity and pneumonia challenge with Pseudomonas aeruginosa in obese and nonobese mice to investigate the effect of obesity on STAT3 activation. We found obese mice with bacterial pneumonia had increased mortality compared with nonobese mice. Inflammatory markers, IL-6 and TNF-α, and lung neutrophil infiltration were elevated at 6 h after pneumonia in both nonobese and obese mice. Obese mice had greater lung injury compared with nonobese mice at 6 h after pneumonia. Leptin and insulin levels were higher in obese mice compared with nonobese mice, and obese mice with pneumonia had higher pulmonary STAT3 activation compared with nonobese mice.

A Comparison of US Medicare Expenditures for Hemodialysis and Peritoneal Dialysis

BACKGROUND

Observations that peritoneal dialysis (PD) may be an effective, lower-cost alternative to hemodialysis for the treatment of ESKD have led to policies encouraging PD and subsequent increases in its use in the United States.

METHODS

In a retrospective cohort analysis of Medicare beneficiaries who started dialysis between 2008 and 2015, we ascertained average annual expenditures (for up to 3 years after initiation of dialysis) for patients ≥67 years receiving in-center hemodialysis or PD. We also determined whether differences in Medicare expenditures across dialysis modalities persisted as more patients were placed on PD. We used propensity scores to match 8305 patients initiating PD with 8305 similar patients initiating hemodialysis.

RESULTS

Overall average expenditures were US$108,656 (2017) for hemodialysis and US$91,716 for PD (proportionate difference, 1.11; 95% confidence interval [CI], 1.09 to 1.13). This difference did not change over time (P for time interaction term=0.14). Hemodialysis had higher estimated intravenous (iv) dialysis drug costs (1.69; 95% CI, 1.64 to 1.73), rehabilitation expenditures (1.35; 95% CI, 1.26 to 1.45), and other nondialysis expenditures (1.34; 95% CI, 1.30 to 1.37). Over time, initial differences in total dialysis expenditures disappeared and differences in iv dialysis drug utilization narrowed as nondialysis expenditures diverged. Estimated iv drug costs declined by US$2900 per patient-year in hemodialysis between 2008 and 2014 versus US$900 per patient-year in PD.

CONCLUSIONS

From the perspective of the Medicare program, savings associated with PD in patients ≥67 years have remained unchanged, despite rapid growth in the use of this dialysis modality. Total dialysis expenditures for the two modalities converged over time, whereas nondialysis expenditures diverged.

Demonstrating Feasibility of an Opportunistic Sampling Approach for Pharmacokinetic Studies of β-Lactam Antibiotics in Critically Ill Children

There has been increasing interest in incorporating β-lactam precision dosing into routine clinical care, but robust population pharmacokinetic models in critically ill children are needed for these purposes. The objective of this study was to demonstrate the feasibility of an opportunistic sampling approach that utilizes scavenged residual blood for future pharmacokinetic studies of cefepime, meropenem, and piperacillin. We aimed to show that opportunistic samples would cover the full concentration-versus-time profiles and to evaluate stability of the antibiotics in whole blood and plasma to optimize future use of the opportunistic sampling approach. A prospective observational study was conducted in a single-center pediatric intensive care unit, where pediatric patients administered at least 1 dose of cefepime, meropenem, or piperacillin/tazobactam and who had residual blood scavenged from samples obtained for routine clinical care were enrolled. A total of 138 samples from 22 pediatric patients were collected in a 2-week period. For all 3 antibiotics, the samples collected covered the entire dosing intervals and were not clustered around specific times. There was high variability in the free concentrations and in the percentage of drug bound to protein. There was less than 15% degradation for meropenem or piperacillin when stored in whole blood or plasma at 4°C after 6 days. Cefepime degraded by more than 15% after 3 days. The opportunistic sampling approach is a powerful and feasible method to obtain sufficient samples to study the variability of drug concentrations and protein binding for future pharmacokinetic studies in the pediatric critical care population.

Weight as a Risk Factor for Mortality in Critically Ill Patients

OBJECTIVES

To explore the hypothesis that obesity is associated with increased mortality and worse outcomes in children who are critically ill.

METHODS

Secondary analysis of the Assessment of Worldwide Acute Kidney Injury, Renal Angina, and Epidemiology study, a prospective, multinational observational study. Patients between 3 months and 25 years across Asia, Australia, Europe, and North America were recruited for 3 consecutive months. Patients were divided into 4 groups (underweight, normal weight, overweight, and obese) on the basis of their BMI percentile for age and sex.

RESULTS

A total of 3719 patients were evaluated, of whom 542 (14%) had a primary diagnosis of sepsis. One thousand fifty-nine patients (29%) were underweight, 1649 (44%) were normal weight, 423 (11%) were overweight, and 588 (16%) were obese. The 28-day mortality rate was 3.6% for the overall cohort and 9.1% for the sepsis subcohort and differed significantly by weight status (5.8%, 3.1%, 2.2%, and 1.8% for subjects with underweight, normal weight, overweight, and obesity, respectively, in the overall cohort [P < .001] and 15.4%, 6.6%, 3.6%, and 4.7% in the sepsis subcohort, respectively [P = .003]). In a fully adjusted model, 28-day mortality risk was 1.8-fold higher in the underweight group versus the normal weight group in the overall cohort and 2.9-fold higher in the sepsis subcohort. Patients who were overweight and obese did not demonstrate increased risk in their respective cohorts. Patients who were underweight had a longer ICU length of stay, increased need for mechanical ventilation support, and a higher frequency of fluid overload.

CONCLUSIONS

Patients who are underweight make up a significant proportion of all patients in the PICU, have a higher short-term mortality rate, and have a more complicated ICU course.

Obesity enhances sepsis-induced liver inflammation and injury in mice

OBJECTIVE

How obesity affects the response to sepsis was not completely understood. It was hypothesized that obesity alters adipose and hepatic tissue inflammation through signal transducer and activator of transcription (STAT3) activation.

METHODS

Male C57BL/6 mice at 6 weeks of age were randomized to a high-fat diet (60% kcal fat) or normal diet (16% kcal fat) for 6 to 7 weeks. Sepsis was then induced by cecal ligation and puncture, and animals were monitored for survival or sacrificed and tissue collected.

RESULTS

High-fat diet-fed mice gained more weight, had increased fat mass, and were glucose intolerant compared with normal diet-fed mice. Obesity increased hepatic neutrophil infiltration and injury after sepsis. Mice with obesity had higher plasma leptin levels compared with mice without obesity. Adipose tissue expression of adiponectin receptor 2, tumor necrosis factor-α, and peroxisome proliferator activated receptor gamma was altered during sepsis and affected by obesity, but the greatest change in adipose tissue expression was in leptin. Septic mice with obesity had lower plasma interleukin-17a, interleukin-23, and tumor necrosis factor-α levels and increased hepatic STAT3 and activator protein-1 activation compared with septic mice without obesity. Ultimately, mice with obesity had a lower probability of survival following sepsis.

CONCLUSIONS

Mice with obesity are more susceptible to sepsis and have higher mortality, in part, through activation of the STAT3 signaling pathway and through activator protein-1 activation.

Short-term high fat feeding increases organ injury and mortality after polymicrobial sepsis

The purpose of this study was to examine the effect of short-term high fat feeding on the inflammatory response in polymicrobial sepsis. Male C57BL/6 mice at 6 weeks of age were randomized to a high-fat diet (HFD) (60% kcal fat) or control diet (CD) (16% kcal fat) for 3 weeks. After 3 weeks of feeding, sepsis was induced by cecal ligation and puncture (CLP) and animals were monitored for survival. In a separate experiment, after 3 weeks of feeding mice underwent CLP and were sacrificed at various time points thereafter. Tissue was collected for biochemical studies. Mice fed a HFD gained more weight and had a greater fat mass compared to CD-fed mice. Mice on a HFD had a lower probability of survival and more severe lung injury compared with CD-fed mice following sepsis. Myeloperoxidase (MPO) activity, an indicator of neutrophil infiltration, was increased in the lung and liver after CLP in HFD-fed mice compared with CD (P < 0.05). The plasma cytokines tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 were increased in both groups after CLP, however, TNF-α and IL-6 levels were lower in HFD mice at 3 h after CLP compared with CD and consistent with lung, but not liver, messenger RNA (mRNA) expression. Leptin levels were higher in HFD-fed mice at 18 h after sepsis compared to baseline levels (P < 0.05). Polymicrobial sepsis increased hepatic nuclear factor-κB (NF-κB) activation in HFD-fed mice after CLP vs. CD-fed mice. Short duration high fat feeding increases mortality and organ injury following polymicrobial sepsis. These effects correspond to changes in NF-κB.

Phosphorylation of extracellular signal-regulated kinase (ERK)-1/2 Is associated with the downregulation of peroxisome proliferator-activated receptor (PPAR)-γ during polymicrobial sepsis

Peroxisome proliferator-activated receptor (PPAR)-γ is a ligand-activated transcription factor and regulates inflammation. Posttranslational modifications regulate the function of PPARγ, potentially affecting inflammation. PPARγ contains a mitogen-activated protein kinase (MAPK) site, and phosphorylation by extracellular signal-regulated kinase (ERK)-1/2 leads to inhibition of PPARγ. This study investigated the kinetics of PPARγ expression and activation in parenchymal and immune cells in sepsis using the MAPK/ERK kinase (MEK)-1 inhibitor, an upstream kinase of ERK1/2. Adult male Sprague Dawley rats were subjected to polymicrobial sepsis by cecal ligation and puncture. Rats received intraperitoneal injection of vehicle or the MEK1 inhibitor PD98059 (5 mg/kg) 30 min before cecal ligation and puncture. Rats were euthanized at 0, 1, 3, 6 and 18 h after cecal ligation and puncture. Control animals used were animals at time 0 h. Lung, plasma and peripheral blood mononuclear cells (PBMCs) were collected for biochemical assays. In vehicle-treated rats, polymicrobial sepsis resulted in significant lung injury. In the lung and PBMCs, nuclear levels of PPARγ were decreased and associated with an increase in phosphorylated PPARγ and phosphorylated ERK1/2 levels. Treatment with the MEK1 inhibitor increased the antiinflammatory plasma adipokine adiponectin, restored PPARγ expression in PBMCs and lung, and decreased lung injury. The inflammatory effects of sepsis cause changes in PPARγ expression and activation, in part, because of phosphorylation of PPARγ by ERK1/2. This phosphorylation can be reversed by ERK1/2 inhibition, thereby improving lung injury.

Changes in peroxisome proliferator-activated receptor-gamma activity in children with septic shock

PURPOSE

To assess changes in peroxisome proliferator-activated receptor-gamma (PPARgamma) in peripheral blood mononuclear cells (PBMC) from critically ill children with sepsis. Additionally, to investigate the effects of sepsis on the endogenous activator of PPARgamma, 15-deoxy-(12,14)-PGJ(2) (15d-PGJ(2)), and the downstream targets of PPARgamma activity, adiponectin and resistin.

METHODS

Single-center, prospective case-control study in critically ill children with systemic inflammatory response syndrome, sepsis or septic shock.

RESULTS

PPARgamma nuclear protein expression was decreased but PPARgamma activity was increased in PBMC from children with septic shock compared with controls. PPARgamma activity on day 1 was significantly higher in patients with higher pediatric risk of mortality (PRISM) score compared with controls [mean 0.22 optical density (OD) +/- standard error of the mean (SEM) 0.03 versus 0.12 OD +/- 0.02; p < 0.001]. Patients with resolved sepsis had increased levels of the endogenous PPARgamma ligand, 15d-PGJ(2), compared with patients with systemic inflammatory response syndrome (SIRS) and septic shock (77.7 +/- 21.7 versus 58 +/- 16.5 pg/ml; p = 0.03). Plasma high-molecular-weight adiponectin (HMWA) and resistin levels were increased in patients with septic shock on day 1 and were significantly higher in patients with higher PRISM scores. Nonsurvivors from sepsis had higher resistin levels on the first day of hospitalization compared with survivors from septic shock [660 ng/ml, interquartile range (IQR) 585-833 ng/ml versus 143 ng/ml, IQR 66-342 ng/ml; p < 0.05].

CONCLUSIONS

Sepsis is associated with altered PPARgamma expression and activity in PBMC. Plasma adipokines correlate with risk of mortality scores in sepsis and may be useful biomarkers. Further studies are needed to understand the mechanisms underlying changes in PPARgamma in sepsis.

Therapeutic benefit of treatment with anti-thymocyte globulin and latent TGF-β1 in the MRL/lpr lupus mouse model

The pathogenesis of systemic lupus erythematosus is believed to involve defects in regulatory T cell (Treg) activity and abnormal activation of B and T lymphocytes. The purpose of this study was to test the therapeutic potential of rabbit anti-mouse thymocyte globulin (ATG), a lymphocyte-depleting agent, in conjunction with transforming growth factor (TGF)-β1, a factor involved in the induction and expansion of Tregs. MRL/lpr mice with active disease were treated with ATG followed by a 12-day course of latent TGF-β1 during the period of lymphocyte repopulation. Treatment with ATG + latent TGF-β1 synergistically inhibited the progression of proteinuria and albuminuria and provided a significant improvement in long-term survival. This therapeutic benefit correlated histologically with reduced glomerular pathology and protein cast formation. The mechanism of action did not involve suppression of autoantibody formation but may involve the activity of CD4+CD25+FoxP3+ Tregs, which were found to be induced by ATG + TGF-β1 treatment in vitro.

Overfeeding-induced weight gain suppresses plasma ghrelin levels in rats

The elevation of plasma ghrelin associated with weight loss has been taken as evidence of a role for ghrelin in the adaptive response to body weight change. However, there has been no clear experimental evidence that circulating ghrelin is suppressed by weight gain. We investigate this issue using a model of involuntary (intra-gastric gavage) overfeeding-induced obesity. Rats were first maintained at normal body weight with 4 daily tube-feedings of liquid diet (2.11 kcal/ml), each delivered at a volume of 9 ml. Gavage volume was then increased to 13 ml/feeding for 2 weeks, during which rats gained 25% of their initial body weight. Fasting plasma ghrelin levels and the response to 9- and 13-ml intra-gastric load sizes were measured during the weight-stable and overfed conditions. We found that: 1) weight gain decreased circulating ghrelin levels; 2) this response could not be attributed to additional food in the gastrointestinal tract; 3) the ghrelin response to nutrient loads was diminished in the obese vs normal-weight conditions. Having discounted diet composition and differences in gastric contents at the time of blood sampling, the decrease in ghrelin levels with overfeeding can be unambiguously attributed to physiological correlates of weight gain.

Inpatient verbal orders and the impact of computerized provider order entry

OBJECTIVE

To describe the characteristics of verbal orders at a tertiary care children's hospital.

STUDY DESIGN

Between August 2003 and January 2004, the computerized provider order entry (CPOE) system was evaluated for the characteristics of verbal orders. The rate of total orders represented by verbal orders and the rate of unsigned verbal orders were examined before, during, and after CPOE implementation.

RESULTS

After CPOE implementation, a mean of 19,996 +/- 521 orders were generated weekly; of these, 2094 +/- 65 (10%) were verbal orders. The greatest rates of verbal orders were from psychiatry (74%) units and involved medication orders (38%; 790/2094). The greatest rates of medication verbal orders were psychotherapeutics (24%; 662/2697). Medical physicians had a larger rate of verbal orders than surgical physicians. The rates of verbal orders and unsigned verbal orders were reduced from 23% and 43% before CPOE implementation to 10% and 9% after implementation, respectively.

CONCLUSIONS

Medication orders from physicians to nurses are the primary source of verbal orders in this tertiary care children's hospital. CPOE implementation significantly affected both verbal orders and the rate of unsigned verbal orders. This type of data is important for institutions aiming to decrease verbal orders and associated medical errors.

15-DEOXY-??12,14-PROSTAGLANDIN J2 (15D-PGJ2), A PEROXISOME PROLIFERATOR ACTIVATED RECEPTOR ?? LIGAND, REDUCES TISSUE LEUKOSEQUESTRATION AND MORTALITY IN ENDOTOXIC SHOCK

Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a nuclear receptor that requires ligand activation for transcription. Experimental studies have shown that 15-deoxy-Delta-PGJ2 (15d-PGJ2) is a natural PPARgamma ligand which has potent anti-inflammatory properties. This study was designed to examine the effect and the molecular mechanisms of 15d-PGJ2 on tissue neutrophil infiltration and survival in endotoxic shock. Male Swiss albino mice were subjected to intraperitoneal injection of Escherichia coli lipopolysaccharide (LPS, 25 mg/kg). Three hours after LPS mice received vehicle or 15d-PGJ2 (1 mg/kg) and continued treatment every 12 hours. Survival was monitored for 72 hours. In a separate experiment, mice were sacrificed 6 hours after LPS and tissue examined. In vehicle-treated mice, LPS injection resulted in a survival rate of 9%. Marked lung injury was characterized by hemorrhage, infiltration of inflammatory cells and reduction of alveolar space. Elevated levels of myeloperoxidase activity in lung and small intestine were indicative of infiltration of neutrophils. Increased expression of intercellular adhesion molecule-1, vascular cellular adhesion molecule-1 and E-selectin were observed in the lung and small intestine. These inflammatory events were associated with reduced expression of PPARgamma and with activation of nuclear factor-kappaB (NF-kappaB) in the lung. Treatment with 15d-PGJ2 improved survival rate to 55%, downregulated expression of adhesion molecules and reduced neutrophil infiltration in tissues. These beneficial effects were associated with reduced activation of NF-kappaB DNA binding, whereas expression and DNA binding of PPARgamma and expression of the cytoprotective heat shock protein (HSP) 70 were increased in the lung. Our data demonstrate that 15d-PGJ2 ameliorates endotoxic shock most likely through repressing the proinflammatory pathway of NF-kappaB and enhancement of the cytoprotective heat shock response.

Effect of Pseudomonas-induced chronic lung inflammation on specific cytotoxic T-cell responses to adenoviral vectors in mice

A mouse model of chronic Pseudomonas-induced bronchopulmonary inflammation that mimics chronic cystic fibrosis (CF) lung disease was employed to determine whether this inflammatory milieu influences immune responses to adenoviral vectors. Pseudomonas-infected and control mice were inoculated intranasally with a second-generation type 2 adenovirus (Ad2) vector (Ad2/betagal-2). After 3 weeks, serum and airway Ad2-specific antibodies and Ad2 vector-directed, cytotoxic T-lymphocyte (CTL) activity in splenocytes were measured. No differences in humoral immunity were observed between Pseudomonas-infected mice and controls. However, there was a two- to three-fold increase in Ad-specific CTL activity in the Pseudomonas-infected mice compared to control mice. MHC class I-dependent antigen presentation by antigen-presenting cells (APC) from lungs of Pseudomonas-infected mice was also significantly increased compared to APC from control mice, suggesting a mechanism that may contribute to increased Ad-specific CD8+ CTL responses. It was concluded that Ad-specific CTL activity is enhanced in the setting of pre-existing chronic Pseudomonas-induced lung inflammation similar to CF lung disease, and that increased antigen presentation via MHC class I in this setting may be one underlying mechanism. These findings underscore the importance of considering the influence of the disease milieu when evaluating modes of gene therapy for such diseases in animal models.

Brainstem melanocortin 3/4 receptor stimulation increases uncoupling protein gene expression in brown fat

Central administration of melanocortin 3 and 4 receptor (MC3/4-R) agonists increases energy expenditure, with the hypothalamus commonly held as the primary site of action. It is also clear, however, that MC4-R are expressed in caudal brainstem structures of relevance to the control of energy expenditure. Three experiments investigated whether hindbrain MC-R contribute to the energy expenditure effects of central MC3/4-R agonist treatments; in each, we examined the effect of fourth intracerebroventricular (i.c.v.) administration of a MC3/4-R agonist, MTII (three injections, each separated by 12 h), on uncoupling protein 1 (UCP-1) gene expression in brown adipose tissue (BAT). First, we compared the effects of fourth and third i.c.v. administration of MTII and found that the hindbrain and forebrain treatments were equally effective at elevating UCP-1 mRNA expression in BAT compared with the respective vehicle-treated group results. A second experiment demonstrated that the fourth i.c.v. MTII-induced rise in UCP-1 expression was mediated by sympathetic outflow to BAT by showing that this response was abolished by surgical denervation of BAT. In the third experiment, we showed that chronic decerebrate rats, like their neurologically intact controls, elevated UCP-1 mRNA expression in response to fourth i.c.v. MTII administration. Taken together, the results indicate that: 1) there is an independent caudal brainstem MC3/4-R trigger for a sympathetically stimulated elevation in BAT UCP-1 gene expression, and 2) the MTII-induced rise in UCP-1 expression can be mediated by circuitry intrinsic to the caudal brainstem and spinal cord.

Interoceptive and integrative contributions of forebrain and brainstem to energy balance control

An anatomically distributed model of energy balance control contrasts with the widely held hypothalamic center model. The distributionist model is recommended by the observations that the caudal brainstem contains critical interoceptive, integrative and neurochemical mediating functions. A prominent example of interoceptive function is sensitivity to the adipose tissue-derived hormone, leptin. To complement the well established focus on hypothalamic leptin receptors (Ob-Rb), we describe an extensive distribution of Ob-Rb in the brainstem. These receptors, moreover, are functionally relevant given the intake suppressive effects of fourth-intracerebroventricular (i.c.v) and brainstem intraparenchymal (in dorsal vagal complex) delivery. A wide variety of intake relevant peptides receptors are found in hypothalamus, but these receptors are also widely distributed in the caudal brainstem. As an example of the functional relevance of these neurochemical mediators, we describe ingestive effects of ligands for melanocortin 3/4 and corticotrophin-releasing hormone receptors obtained with brainstem ventricular and parenchymal (dorsal vagal complex and parabrachial nucleus) delivery. It is clear that responses obtained from hypothalamic treatments can arise independently from stimulation of caudal brainstem receptors. We have used the chronic decerebrate preparation to ask whether the brainstem contains integrative substrates sufficient to mediate behavioral responses to variations in physiological state. The experiments reveal that the brainstem is indeed sufficient for the integration of taste and gastrointestinal signals that co-determine the size of meals in the short term. Decerebrate rats, however, do not respond to food deprivation or to reductions in the number of daily feeding opportunities. These results suggest that the brainstem in neural isolation from forebrain influence is not sufficient for ingestive response to systemic/metabolic signals that affect intake over the long term. The relative contribution of brainstem and forebrain substrates to long-term intake and body weight control in the neurologically intact animal, remains unclear. The data reviewed support a distributed anatomical model of energy balance and recommend increased attention to specific responses (behavioral, autonomic and endocrine) that are mediated by local (brainstem or forebrain) interoceptive and integrative processes, and those requiring bi-directional interactions.

The EGL-3 proprotein convertase regulates mechanosensory responses of Caenorhabditis elegans

Neuroactive peptides are packaged as proproteins into dense core vesicles or secretory granules, where they are cleaved at dibasic residues by copackaged proprotein convertases. We show here that the Caenorhabditis elegans egl-3 gene encodes a protein that is 57% identical to mouse proprotein convertase type 2 (PC2), and we provide evidence that this convertase regulates mechanosensory responses. Nose touch sensitivity (mediated by ASH sensory neurons) is defective in mutants lacking GLR-1 glutamate receptors (GluRs); however, mutations eliminating the egl-3 PC2 restored nose touch sensitivity to glr-1 GluR mutants. By contrast, body touch sensitivity (mediated by the touch cells) is greatly diminished in egl-3 PC2 mutants. Taken together, these results suggest that egl-3 PC2-processed peptides normally regulate the responsiveness of C. elegans to mechanical stimuli.

Dissociation of licking and volume intake controls in rats ingesting glucose and maltodextrin

The volume of fluid that rats acquire with each lick was systematically varied across short-term tests with 12.5% glucose (Experiment 1) or 12.5% maltodextrin (Experiment 2). For glucose, rats increased the number of licks emitted as lick volume was reduced such that meal size remained remarkably stable across all (8, 4, and 2 microl) but the smallest (1 microl) lick volume conditions tested. Rats similarly compensated for lick volume reduction (8 to 4 microl) with maltodextrin by approximately doubling the number of licks emitted. Meal duration and a number of lick-microstructural parameters (initial ingestion rate, mean burst duration, terminal lick and ingestion rates, and burst duration) were not correlated with the intake outcome insofar as they varied significantly across conditions over which intake remained stable. Thus, in response to lick volume manipulation, rats demonstrated an impressive degree of behavioral flexibility in what may be regarded as a defense of meal size.

Accidental germ-line modifications through somatic cell gene therapies: some ethical considerations

Proposed somatic cell gene-therapies (especially those involving in utero therapies) may involve a small risk of germ-line modifications; this risk has engendered serious concern, and arguments have been made that such therapies ought not be pursued if such risks exists. We argue here that while pursuing deliberate germ-line modifications in humans would be inappropriate given the current state of the art, the risk of accidental germ-line modifications from most currently proposed in utero gene therapy is no different in kind or degree from other risks regularly taken in medical procedures. Given the possible benefits of such therapies, we argue that the risk of accidental germ-line modifications is well worth taking in these cases.

Adenoviral vector expressing ICP47 inhibits adenovirus-specific cytotoxic T lymphocytes in nonhuman primates

Studies from several laboratories have shown that administration of E1-deleted Ad vectors results only in transient transgene expression in the lungs of immunocompetent animals. This is due, at least in part, to destruction of vector-transduced cells by host cellular immune responses (predominantly CD8(+) CTLs) directed against viral proteins and/or immunogenic transgene products. We have previously demonstrated that E1-deleted Ad vectors can lead to persistent expression of human cystic fibrosis transmembrane conductance regulator (hCFTR) in the lungs of several strains of immunocompetent mice, despite the presence of Ad-specific CTLs. However, we found that these same vectors gave rise only to transient hCFTR expression in the lungs of rhesus monkeys. We have constructed new Ad vectors that coexpress both hCFTR and the ICP47 gene from herpes simplex virus. ICP47 has been shown to inhibit the transporter associated with antigen presentation, thus blocking major histocompatibility antigen I (MHC class I)-mediated antigen presentation to CD8(+) T cells. The Ad/hCFTR/ICP47 vector decreased levels of cell-surface MHC class I molecules on infected monkey and human cell lines. Similar results were obtained with primary human cells and primary monkey airway epithelial cells. In vitro studies showed that the Ad/hCFTR/ICP47 vector decreased cytolysis by both monkey and human CTLs. When Ad/hCFTR/ICP47 was administered to the lungs of rhesus monkeys, it inhibited the generation of Ad-specific CTLs. However, natural killer cell activity was enhanced in monkeys treated with the Ad/hCFTR/ICP47 vector.

Inhibitory effect of cystic fibrosis sputum on adenovirus-mediated gene transfer in cultured epithelial cells

Effective gene transfer to the airway epithelial cells of individuals with cystic fibrosis (CF) requires gene therapy vectors to effectively penetrate the mucous lining of the airways of these patients. In this study, we examined the effects of the aqueous sol fraction of sputum recovered from CF patients (CF sol) on adenovirus (Ad)-mediated gene transfer to cultured epithelial cells. Sputum collected from patients with CF was separated into aqueous sol and gel fractions by ultracentrifugation and the sol fraction from different individuals was pooled. To determine if CF sol affects Ad-mediated transfection, Fisher rat thyroid (FRT) epithelial cells or normal human bronchial epithelial (NHBE) cells were infected with an Ad encoding beta-galactosidase (Ad2/betagal-2) in the presence or absence of the pooled CF sol. Transfection efficiency was determined by measuring beta-Gal activity. CF sol significantly inhibited Ad2-mediated gene transfer in a dose-dependent manner when the vector was incubated with CF sol prior to exposure to the cells. In contrast, preincubation of the cells with the sol was without effect. The inhibition of Ad-mediated gene transfer by CF sol was not related to its low pH, was abrogated by preadsorption with an Ad2 serotype vector, and was neutralized by heat treatment, but was not affected by treatment with protease inhibitors. Analysis of CF sol fractions from seven different individuals with CF showed inhibition of Ad-mediated gene transfer in four of the seven samples tested and, further, the inhibitory effect was correlated with the presence of Ad-specific antibodies. We conclude that preexisting adenovirus-specific antibodies present in some of the patient samples were the predominant factor inhibiting Ad-mediated gene transfer.

Food deprivation does not potentiate glucose taste reactivity responses of chronic decerebrate rats

The chronic supracollicular decerebrate (CD) rat fails to increase meal size in response to systemic/metabolic aspects of food deprivation. Here we asked whether or not deprivation increases immediate oral motor responding to taste stimuli (taste reactivity) in CD rats, as it does in neurologically intact controls. The responses of CD rats were evaluated as functions of glucose concentration and deprivation state, with taste reactivity responses recorded myographically during 15-s intraoral infusions and during 45-s post-infusion periods. Five glucose concentrations (0, 3.2, 6. 25, 12.5, 25%) were each presented three times during each test session. The rats were tested when not-deprived (i.e. receiving their full complement of gavage feedings), deprived (23.5 h) of food and water, and deprived of food but not water. The number of oral motor responses emitted increased monotonically with stimulus concentration; during oral infusions the increase was greatest over the lower half of the concentration range, whereas responding increased linearly with concentration in the post-infusion period. This CD response profile resembled that obtained previously with neurologically intact rats tested according to the same protocols. In contrast to results obtained in intact rats, deprivation did not influence the CD's response to glucose at any concentration or for any observation period. Although the caudal brainstem may receive and process information associated with deprivation state, neural interactions between forebrain and brainstem structures appear necessary for the behavioral expression of deprivation effects on meal size or, as we can now conclude, on immediate oral motor responses to taste stimuli.

Long-term effects on feeding and body weight after stimulation of forebrain or hindbrain CRH receptors with urocortin

Research on the contribution of CRH receptor stimulation to energy homeostasis has focused on forebrain substrates. In this study, we explored the effects of caudal brainstem administration of the CRH receptor agonist, urocortin, on food intake and body weight, and on plasma glucose and corticosterone (CORT) in non-deprived rats. Urocortin (0, 0.3, 1, 3 microg) delivered, respectively, to the fourth and lateral ventricles yielded substantial suppression of food intake measured 2, 4 and 24 h later. A significant but more modest anorexia was observed between 24 and 48 h after injection. Intake responses did not differ between the injection sites, but body weight loss measured 24 h after lateral-i.c.v. injection was substantially greater than that after fourth-i.c.v. injection. Fourth-i.c.v. urocortin administration (3 microg) produced substantial elevations in plasma glucose and CORT that were not distinguishable in magnitude and duration from responses to lateral-i.c.v. delivery. Unilateral microinjection of urocortin into the dorsal vagal complex significantly reduced 24-h food intake at a dose (0.1 microg) that was subthreshold for the response to ventricular administration, suggesting that fourth-i.c.v. effects are mediated in part by stimulation of CRH receptors in this region of the caudal brainstem. The results indicate that similar effects can be obtained from stimulation of anatomically disparate populations of CRH receptors, and that interactions between forebrain and hindbrain structures should be considered in the evaluation of CRH contributions to food intake and body weight control.

The role of the dorsal vagal complex and the vagus nerve in feeding effects of melanocortin-3/4 receptor stimulation

Fourth intracerebroventricular (4th-icv) administration of the melanocortin-3/4 receptor (MC3/4-R) agonist, MTII, reduces food intake; the antagonist, SHU9119, increases feeding. The dorsal motor nucleus of the vagus nerve (DMX) contains the highest density of MC4-R messenger RNA in the brain. To explore the possibility that the DMX contributes to 4th-icv MC4-R effects, we delivered doses of MTII and SHU9119 that are subthreshold for ventricular response unilaterally through a cannula centered above the DMX. MTII markedly suppressed 2-h (50%), 4-h (50%), and 24-h (33%) intake. Feeding was significantly increased 4 h (50%) and 24 h (20%) after SHU9119 injections. These results suggest that receptors in the DMX, or the dorsal vagal complex more generally, underlie effects obtained with 4th-icv administration of these ligands. We investigated possible vagal mediation of 4th-icv MTII effects by giving the agonist to rats with subdiaphragmatic vagotomy. MTII suppressed 2-, 4-, and 24-h liquid diet intake (approximately 80%) to the same extent in vagotomized and surgical control rats. We conclude that stimulation or antagonism of MC3/4-Rs in the dorsal vagal complex yields effects on food intake that do not require an intact vagus nerve.

Immunogene therapy for murine melanoma using recombinant adenoviral vectors expressing melanoma-associated antigens

Adenoviral vectors expressing tumor-associated antigens can be used to evoke a specific immune response and inhibit tumor growth. In this study, we tested the efficacy of adenoviral vectors encoding human gp100 (Ad2/hugp100), murine gp100 (Ad2/mugp100), or murine TRP-2 (Ad2/muTRP-2) for their ability to elicit a specific cellular immune response and inhibit the growth of B16 melanoma tumor cells in the mouse. C57BL/6 mice were immunized with Ad2/hugp100, Ad2/mugp100, or Ad2/muTRP-2 either 2 weeks prior to B16-F10 tumor challenge (prophylactic treatment) or 3 days after tumor challenge (active treatment). Ad2/hugp100 and Ad2/muTRP-2 administered to two or more intradermal (i.d.) sites inhibited subsequent subcutaneous tumor growth in > or = 80% of the mice and elicited an antigen-specific cytotoxic T lymphocyte response, whereas other administration routes were not as effective. Ad2/mugp100 administered to two i.d. sites did not inhibit tumor growth or provoke cellular immunity. Immunization was less effective with active treatment where tumor growth was not significantly inhibited by a single dose of either Ad2/muTRP-2 or Ad2/hugp100. However, increasing the number of intradermal immunization sites and the number of doses resulted in progressive improvements in protection from tumor growth in the active treatment model. In conclusion, breaking host tolerance to elicit protective immunity by using adenoviral vectors expressing melanoma-associated antigens is dependent upon the choice of antigen, the site of administration, and the number of doses. These observations provide insights into the clinical applicability of adenoviral vaccines for immunotherapy of malignant diseases.

Mutations in ACTN4, encoding alpha-actinin-4, cause familial focal segmental glomerulosclerosis

Focal and segmental glomerulosclerosis (FSGS) is a common, non-specific renal lesion. Although it is often secondary to other disorders, including HIV infection, obesity, hypertension and diabetes, FSGS also appears as an isolated, idiopathic condition. FSGS is characterized by increased urinary protein excretion and decreasing kidney function. Often, renal insufficiency in affected patients progresses to end-stage renal failure, a highly morbid state requiring either dialysis therapy or kidney transplantation. Here we present evidence implicating mutations in the gene encoding alpha-actinin-4 (ACTN4; ref. 2), an actin-filament crosslinking protein, as the cause of disease in three families with an autosomal dominant form of FSGS. In vitro, mutant alpha-actinin-4 binds filamentous actin (F-actin) more strongly than does wild-type alpha-actinin-4. Regulation of the actin cytoskeleton of glomerular podocytes may be altered in this group of patients. Our results have implications for understanding the role of the cytoskeleton in the pathophysiology of kidney disease and may lead to a better understanding of the genetic basis of susceptibility to kidney damage.

CaMKII regulates the density of central glutamatergic synapses in vivo

Synaptic connections undergo a dynamic process of stabilization or elimination during development, and this process is thought to be critical in memory and learning and in establishing the specificity of synaptic connections. The type II calcium- and calmodulin-dependent protein kinase (CaMKII) has been proposed to be pivotal in regulating synaptic strength and in maturation of synapses during development. Here we describe how CaMKII regulates the formation of central glutamatergic synapses in Caenorhabditis elegans. During larval development, the density of ventral nerve cord synapses containing the GLR-1 glutamate receptor is held constant despite marked changes in neurite length. The coupling of synapse number to neurite length requires both CaMKII and voltage-gated calcium channels. CaMKII regulates GLR-1 by at least two distinct mechanisms: regulating transport of GLR-1 from cell bodies to neurites; and regulating the addition or maintenance of GLR-1 to postsynaptic elements.

Dual effects of somatostatin analog octreotide on gastric emptying during and after intragastric fill

The effect of the somatostatin analog agonist octreotide (Oct) on gastric emptying of 12.5% glucose during and after intragastric fill was examined in nondeprived rats equipped with stainless steel gastric fistulas. The rate of intragastric infusion (1.0 ml/min) and the volumes delivered (6 or 12 ml) were within the ranges typically observed in rats normally ingesting the same stimulus. In experiment 1, a dose-related suppression of glucose emptying during 12-min infusions was obtained in response to Oct (0, 0.0014, 0.014, 0.14, and 1.4 nmol/kg sc) injected 60 min before the test. The highest dose tested yielded a 37% suppression of glucose solute emptying during fill. In experiment 2, the suppression of emptying during fill induced by Oct (1.4 nmol/kg) was reversed by 10 or 40 microgram/kg of the somatostatin antagonist cyclo(7-aminoheptanoyl-Phe-D-Trp-Lys-Thr[Bzl]). The antagonist did not by itself affect emptying. Experiment 3 showed that the suppression of emptying obtained with 0.14 and 1.4 nmol/kg Oct had disappeared when the gastric sample was withdrawn 36 min after the termination of 12-min glucose infusions. Experiment 4 showed that the Oct-induced reductions in emptying during 6- and 12-min infusions, in fact, were reversed within 6 min after infusion offset. The point of transition between suppressed and increased emptying did not depend on time from injection or from infusion onset but was linked to the offset of the intragastric infusion regardless of its duration. The present findings support the notion that separable mechanisms govern gastric emptying during vs. after gastric fill.

Facilitation of synaptic transmission by EGL-30 Gqalpha and EGL-8 PLCbeta: DAG binding to UNC-13 is required to stimulate acetylcholine release

We show that neurotransmitter release at Caenorhabditis elegans neuromuscular junctions is facilitated by a presynaptic pathway composed of a Gqalpha (EGL-30), EGL-8 phospholipase Cbeta (PLCbeta), and the diacylglycerol- (DAG-) binding protein UNC-13. Activation of this pathway increased release of acetylcholine at neuromuscular junctions, whereas inactivation decreased release. Phorbol esters stimulated acetylcholine release, and this effect was blocked by a mutation that eliminates phorbol ester binding to UNC-13. Expression of a constitutively membrane-bound form of UNC-13 restored acetylcholine release to mutants lacking the egl-8 PLCbeta. Activation of this pathway with muscarinic agonists caused UNC-13 to accumulate in punctate structures in the ventral nerve cord. These results suggest that presynaptic DAG facilitates synaptic transmission and that part of this effect is mediated by UNC-13.

Effect of hepatic glucose infusion on glucose intake and licking microstructure in deprived and nondeprived rats

The effects of hepatic-portal glucose or saline infusions on intake and the temporal distribution of licking (lick microstructure) were evaluated in nondeprived and in 20.5-h food-deprived rats. Rats received portal infusions of isotonic glucose or saline (0.1 ml/min) for 2 h before and then throughout a 90-min period of access to a spout that delivered 12.5% glucose. Overall, a significant treatment-related intake suppression was obtained in nondeprived but not in deprived groups. For both groups, however, there was a significant positive linear relationship between the amount individual rats consumed under the saline (baseline) infusion condition and the extent to which portal glucose infusion suppressed intake. The linear fit for the deprived group was similar in slope, but right shifted, relative to the best fit for the nondeprived group. The individual-subject and group differences in response to portal glucose infusion are discussed in relation to the inconsistent literature on this treatment's short-term intake effects. We focused analysis of the licking pattern on those rats for which a prominent portal glucose infusion effect was obtained (i.e., nondeprived rats with higher than average baseline intakes). Features of the lick pattern associated with taste evaluation (1st min lick rate; lick burst duration) were not significantly affected by portal glucose infusion. Rather, the minute-by-minute rate of ingestion under glucose infusion declined more rapidly than under baseline tests, indicating that portal glucose infusion enhanced the inhibitory influence of the accumulating postingestive load.

Serotonin inhibition of synaptic transmission: Galpha(0) decreases the abundance of UNC-13 at release sites

We show that serotonin inhibits synaptic transmission at C. elegans neuromuscular junctions, and we describe a signaling pathway that mediates this effect. Release of acetylcholine from motor neurons was assayed by measuring the sensitivity of intact animals to the acetylcholinesterase inhibitor aldicarb. By this assay, exogenous serotonin inhibited acetylcholine release, whereas serotonin antagonists stimulated release. The effects of serotonin on synaptic transmission were mediated by GOA-1 (a Galpha0 subunit) and DGK-1 (a diacylglycerol [DAG] kinase), both of which act in the ventral cord motor neurons. Mutants lacking goa-1 G(alpha)0 accumulated abnormally high levels of the DAG-binding protein UNC-13 at motor neuron nerve terminals, suggesting that serotonin inhibits synaptic transmission by decreasing the abundance of UNC-13 at release sites.

A philosophical critique of decision analysis as a tool in genetic testing

Decision analysis has been proposed as a method to improve the quality of decisions made by individuals facing choices about genetic testing for Alzheimer disease (AD) and other conditions where information about risk is highly uncertain. This paper provides a philosophical critique of two schools of decision analysis, explaining the conceptual limitations inherent in each approach. A central difference between the two approaches is their stance toward the ontological status of patient preferences and values. Are an individual's preferences and values about genetic testing simply assessed or extracted during decision analysis or are they created during the decision analysis itself? How closely can preferences conform to the axioms of rational choice theory? A case study of one individual's experience with decision analysis demonstrates the strengths and weaknesses of decision analysis in the context of genetic testing for AD.

Induction of antitumor immunity with dendritic cells transduced with adenovirus vector-encoding endogenous tumor-associated antigens

Dendritic cells (DCs) are professional Ag-presenting cells that are being considered as potential immunotherapeutic agents to promote host immune responses against tumor Ags. In this study, recombinant adenovirus (Ad) vectors encoding melanoma-associated Ags were used to transduce murine DCs, which were then tested for their ability to activate CTL and induce protective immunity against B16 melanoma tumor cells. Immunization of C57BL/6 mice with DCs transduced with Ad vector encoding the hugp100 melanoma Ag (Ad2/hugp100) elicited the development of gp100-specific CTLs capable of lysing syngeneic fibroblasts transduced with Ad2/hugp100, as well as B16 cells expressing endogenous murine gp100. The induction of gp100-specific CTLs was associated with long term protection against lethal s.c. challenge with B16 cells. It was also possible to induce effective immunity against a murine melanoma self Ag, tyrosinase-related protein-2, using DCs transduced with Ad vector encoding the Ag. The level of antitumor protection achieved was dependent on the dose of DCs and required CD4+ T cell activity. Importantly, immunization with Ad vector-transduced DCs was not impaired in mice that had been preimmunized against Ad to mimic the immune status of the general human population. Finally, DC-based immunization also afforded partial protection against established B16 tumor cells, and the inhibition of tumor growth was improved by simultaneous immunization against two melanoma-associated Ags as opposed to either one alone. Taken together, these results support the concept of cancer immunotherapy using DCs transduced with Ad vectors encoding tumor-associated Ags.

Novel role for E4 region genes in protection of adenovirus vectors from lysis by cytotoxic T lymphocytes

Target cells infected with adenovirus (Ad) vectors containing intact E3 and E4 regions were found to be relatively resistant to lysis by Ad-specific cytotoxic T lymphocytes. Elements from both the E3 and the E4 regions were required for this effect, leading to the identification of a previously undescribed role for E4 gene products in resistance to cytolysis.

Adenovirus-mediated delivery of fas ligand inhibits intimal hyperplasia after balloon injury in immunologically primed animals

BACKGROUND

Adenoviral constructs have been used for studies of injury-induced vascular hyperplasia in immunologically naive laboratory animals, but their usefulness for intra-arterial gene therapy may be limited by the prevalence of preexisting immunity to adenovirus in the patient population. Here, we explored the efficacy of adenovirus-mediated transfer of Fas ligand, a cytotoxic gene with immunomodulatory properties, in inhibiting injury-induced vascular lesion formation in both naive and immunologically primed animals.

METHODS AND RESULTS

Lesion formation was evaluated in balloon-injured carotid arteries of naive and adenovirus-immunized rats that were infected with adenoviral constructs expressing Fas ligand (Ad-FasL), the cyclin-dependent kinase inhibitor p21 (Ad-p21), or beta-galactosidase (Ad-betagal). In naive rats, Ad-FasL induced apoptosis in medial vascular smooth muscle cells and inhibited intimal hyperplasia by 60% relative to Ad-betagal-treated vessels (P<0.05), whereas the cytostatic agent Ad-p21 decreased lesion size by 58% (P<0.05). In animals preimmunized with an adenoviral vector containing no transgene, Ad-FasL significantly inhibited neointima formation (73% reduction, P<0.05), but Ad-p21 failed to inhibit neointima formation relative to controls. Immunologically primed rats displayed robust T-cell infiltration in Ad-p21- and Ad-betagal-treated vessels, but T-cell infiltration was markedly attenuated in Ad-FasL-treated vessels.

CONCLUSIONS

Our data demonstrate that adenovirus-mediated Fas ligand delivery can inhibit intimal hyperplasia in both immunologically primed and naive animals, whereas the efficacy of an adenovirus-mediated p21 delivery is limited to immunologically naive animals. This study documents, for the first time, the therapeutic efficacy of intravascular adenoviral gene transfer in animals with preexisting immunity to adenovirus.

Distinct signaling pathways mediate touch and osmosensory responses in a polymodal sensory neuron

The Caenorhabditis elegans ASH sensory neurons mediate responses to nose touch, hyperosmolarity, and volatile repellent chemicals. We show here that distinct signaling pathways mediate the responses to touch and hyperosmolarity. ASH neurons distinguish between these stimuli because habituation to nose touch has no effect on the response to high osmolarity or volatile chemicals (1-octanol). Mutations in osm-10 eliminate the response to hyperosmolarity but have no effect on responses to nose touch or to volatile repellents. OSM-10 is a novel cytosolic protein expressed in ASH and three other classes of sensory neurons. Mutations in two other osmosensory-defective genes, eos-1 and eos-2, interact genetically with osm-10. Our analysis suggests that nose touch sensitivity and osmosensation occur via distinct signaling pathways in ASH and that OSM-10 is required for osmosensory signaling.

Corticotropin-releasing factor-induced suppression of gastric emptying in the rat is blocked by cyclo(7-aminoheptanoyl-phe-D-TRP-LYS-THR[BZL], an in vivo somatostatin antagonist

Corticotropin-releasing factor (CRF) acts centrally to suppress gastric emptying and increase plasma levels of somatostatin in rats. The experiments were conducted to examine whether cyclo(7-aminoheptanoyl-phe-D-TRP-LYS-THR[BZL]), which acts as a somatostatin antagonist in vivo, blocks the effect of CRF on gastric emptying of glucose. Sprague-Dawley rats were implanted with chronic intragastric fistulas and guide cannulas for fourth intracerebroventricular (4th i.c.v.) delivery. The stomach was evacuated after the offset of a 12-min intragastric glucose infusion (12.5%, 1.0 ml/min). CRF, (1000 pmol) injected 4th i.c.v. suppressed solute emptying by 44% as compared to vehicle (P < 0.001). Pretreatment with cyclo(7-aminoheptanoyl-phe-D-TRP-LYS-THR[BZL]), 40 microg/kg, s.c., having no effect when delivered alone, blocked the effect of CRF on emptying. The results suggest that endogenously released somatostatin participates in CRF-induced suppression of gastric emptying during gastric fill.

Brainstem application of melanocortin receptor ligands produces long-lasting effects on feeding and body weight

Recent evidence suggests that the central melanocortin (MC) system is a prominent contributor to food intake and body weight control. MC receptor (MC-R) populations in the arcuate and paraventricular nuclei are considered probable sites of action mediating the orexigenic effects of systemically or intracerebroventricularly administered ligands. Yet, the highest MC4-R density in the brain is found in the dorsal motor nucleus of the vagus nerve, situated subjacent to the commissural nucleus of the solitary tract, a site of pro-opiomelanocortin mRNA expression. We evaluated the contribution of the caudal brainstem MC system by (1) performing respective dose-response analyses for an MC-R agonist (MTII) and antagonist (SHU9119) delivered to the fourth ventricle, (2) comparing, in the same rats, the fourth intracerebroventricular dose-response profiles to those obtained with lateral intracerebroventricular delivery, and (3) delivering an effective dose of MTII or SHU9119 to rats before a 24 hr period of food deprivation. Fourth intracerebroventricular agonist treatment yielded a dose-dependent reduction of short-term (2 and 4 hr) and longer-term (24 hr) food intake and body weight. Fourth intracerebroventricular antagonist treatment produced the opposite pattern of results: dose-related increases in food intake and corresponding increases in body weight change for the 24-96 hr observation period. Comparable dose-response functions for food intake and body weight were observed when these compounds were delivered to the lateral ventricle. Results from deprived rats (no effect of MTII or SHU9119 on weight loss) support the impression derived from the dose-response analyses that the body weight change that follows MC treatments is secondary to their respective effects on food intake. Results support the relevance of the brainstem MC-R complement to the control of feeding.

Analytical issues in the evaluation of food deprivation and sucrose concentration effects on the microstructure of licking behavior in the rat

A microstructural analysis of licking behavior in nondeprived and 23-hr food-deprived rats (n = 15) presented with various sucrose solutions (0.03-1.0 M) in daily single-bottle, 1-hr sessions was conducted. Food deprivation and concentration interacted to increase total licks. The effects of food deprivation and concentration on burst size (BS), burst number (BN), and other parameters varied as a function of the pause criterion (PC; 0.3-100 s) used to define licking bursts. A rationale for selecting a 1-s PC for further analysis is presented. Despite the lack of correlations between temporally contiguous burst and pause combinations, mean BS decreased and pause duration increased as meals progressed. At the 1-s PC, BS increased linearly with concentration, implying that this microstructural parameter is influenced in part by taste. Food deprivation did not affect BS but rather increased BN and proportionally extended the meal duration.

LIN-10 is a shared component of the polarized protein localization pathways in neurons and epithelia

We tested the model that neurons and epithelial cells use a shared mechanism for polarized protein sorting by comparing the pathways for localizing basolateral and postsynaptic proteins in C. elegans. GLR-1 glutamate receptors are localized to postsynaptic elements of central synapses and, when ectopically expressed, to basolateral membranes of epithelial cells. Proper localization of GLR-1 in both neurons and epithelia requires the PDZ protein LIN-10, defining LIN-10 as a shared component of the basolateral and postsynaptic localization pathways. Changing the GLR-1 carboxy-terminal sequence from a group I PDZ-binding consensus (-TAV) to a group II consensus (-FYV) restores GLR-1 synaptic localization in lin-10 mutants. Thus, these interneurons utilize at least two separate postsynaptic localization pathways.

Adenovirus-mediated persistent cystic fibrosis transmembrane conductance regulator expression in mouse airway epithelium

Replication-defective adenovirus (Ad) vectors have been used for gene transfer to the respiratory epithelium of experimental animals and individuals with cystic fibrosis. Studies from several laboratories have suggested that administration of first-generation Ad vectors results only in transient gene expression in the lung, due at least in part to destruction of vector-transduced cells by host cellular immune responses directed against viral proteins and/or immunogenic transgene products. We have constructed new Ad2-based, E1-deleted vectors encoding a weakly immunogenic transgene, the human cystic fibrosis transmembrane conductance regulator (hCFTR) under the control of the cytomegalovirus enhancer-promoter. These vectors contain wild-type E2 and E4 regions. These new Ad/CFTR vectors were instilled into the lungs of immunocompetent C57BL/6, BALB/c, and C3H mice. In vitro cytotoxic T lymphocyte (CTL) analysis indicated the presence of Ad-specific CTLs in treated mice. However, we were not able to demonstrate a CTL response specific for hCFTR. Reverse transcriptase PCR analysis demonstrated that hCFTR mRNA expression continued in all three strains of mice for at least 70 days, the last time point analyzed. The E3 region did not play a significant role in persistence of the Ad/CFTR vectors in the mouse lung. Functional hCFTR expression was also observed in the nasal epithelia of CF mutant mice. These results suggest that long-term expression of hCFTR is possible in the airway epithelia of immunocompetent mice without radical modification of Ad vector and in spite of the presence of CTLs.

Brain fos-like immunoreactivity in chronic decerebrate and neurologically intact rats given 2,5-anhydro-D-mannitol

Injection of the fructose analogue, 2,5-anhydro-d-mannitol (2,5-AM), increases food intake and Fos-like immunoreactivity (Fos-li) in both brainstem and forebrain structures. Because of the interconnections between brainstem and forebrain areas, it has not been possible to determine whether or to what extent induction of Fos-li in a given region reflects brainstem-forebrain interactions. We addressed this issue using chronic decerebrate (CD) rats with complete transections of the neuroaxis at the meso-diencephalic juncture. CD and neurologically intact control rats were injected (i.p.) with saline or 400 mg/kg 2,5-AM and brains were examined for Fos-li. Both intact and CD rats showed increased Fos-li in the nucleus of the solitary tract (NTS) after injection of 2,5-AM as compared with saline. 2, 5-AM treatment increased Fos-li in the external lateral division of parabrachial nucleus (PBNel) in intact but not in CD rats, suggesting that descending projections from the forebrain may play a role in the activation of PBNel neurons after 2,5-AM injection. Decerebration eliminated significant 2,5-AM-induced Fos-li responses in forebrain structures, including the paraventricular nucleus, supraoptic nucleus, bed nucleus of the stria terminalis and central nucleus of the amygdala. The results are consistent with the hypothesis that the activation of forebrain structures after 2,5-AM treatment is due to stimulation by ascending projections from the brainstem.

Partial restoration of cAMP-stimulated CFTR chloride channel activity in DeltaF508 cells by deoxyspergualin

Deletion of the codon encoding phenylalanine 508 (DeltaF508) is the most common mutation in cystic fibrosis (CF) and results in a trafficking defect. Mutant DeltaF508-CF transmembrane conductance regulator (CFTR) protein retains functional activity, but the nascent protein is recognized as abnormal and, in consequence, is retained in the endoplasmic reticulum (ER) and degraded. It has been proposed that this retention in the ER is mediated, at least in part, by the cellular chaperones heat shock protein (HSP) 70 and calnexin. We have investigated the ability of deoxyspergualin (DSG), a compound known to compete effectively for binding with HSP70 and HSP90, to promote trafficking of DeltaF508-CFTR to the cell membrane. We show that DSG treatment of immortalized human CF epithelial cells (DeltaF508) and cells expressing recombinant DeltaF508-CFTR partially restored cAMP-stimulated CFTR Cl- channel activity at the plasma membrane. Although there are several possible explanations for these results, one simple interpretation is that DSG may have altered the interaction between DeltaF508-CFTR and its associated chaperones. If this is correct, agents capable of altering the normal functioning of cellular chaperones may provide yet another means of restoring CFTR Cl- channel activity to CF subjects harboring this class of mutations.