The association between Barrett's esophagus and Helicobacter pylori infection: a meta-analysis

Objective: The effect of Helicobacter pylori on Barrett’s esophagus is poorly understood. We conducted a meta‐analysis to summarize the existing literature examining the effect that H. pylori has on Barrett’s esophagus. Design: We performed a comprehensive search to identify studies pertaining to the association between H. pylori and Barrett’s esophagus. We conducted meta‐regression analyses to identify sources of variation in the effect of H. pylori on Barrett’s esophagus. Results: Our analysis included a total of 49 studies that examined the effect of H. pylori on Barrett’s esophagus and seven studies that examined the effect of cag A positivity on Barrett’s esophagus. Overall, H. pylori, and even more so cag A, tended to be protective for Barrett’s esophagus in most studies; however, there was obvious heterogeneity across studies. The effect of H. pylori on Barrett’s esophagus varied by geographic location and in the presence of selection and information biases. Only four studies were found without obvious selection and information bias, and these showed a protective effect of H. pylori on Barrett’s esophagus (Relative risk = 0.46 [95% CI: 0.35, 0.60]). Conclusions: Estimates for the effect of H. pylori on Barrett’s esophagus were heterogeneous across studies. We identified selection and information bias as potential sources of this heterogeneity. Few studies without obvious selection and information bias have been conducted to examine the effect of H. pylori on Barrett’s esophagus, but in these, H. pylori infection is associated with a reduced risk of Barrett’s esophagus.     

Nothofagus dombeyi regeneration in declining Austrocedrus chilensis forests: Effects of overstory mortality and climatic events

This research examines the regeneration dynamics of Nothofagus dombeyi and Austrocedrus chilensis in A. chilensis-dominated forests growing near the eastern limit of N. dombeyi where precipitation is limiting. In these forests the widespread decline and mortality of overstory A. chilensis trees, known as ‘mal del ciprés’ (cypress sickness), generates large canopy gaps in which new individuals establish. Our objective was to study the population dynamics of N. dombeyi and A. chilensis in these forests to investigate the influences of overstory tree death and climatic variation on establishment. We sampled 6 symptomatic A. chilensis stands and used dendrochronological techniques to reconstruct basal area development and regeneration establishment over time. Bivariate event analysis was performed to examine the temporal relationships between tree establishment and mortality events and climatic variation. Overstory A. chilensis trees established as post-fire cohorts, with subsequent establishment of A. chilensis and N. dombeyi during the past 50–60 years. Regeneration in the past two decades was primarily N. dombeyi. The establishment of both A. chilensis and N. dombeyi was synchronous with overstory tree mortality events, but it was more consistent among stands and prolonged for N. dombeyi. Establishment of A. chilensis was not associated with climatic events but N. dombeyi establishment was synchronous with droughts, possibly related to climate-driven mortality creating canopy gaps or reducing competition within gaps. We have demonstrated that N. dombeyi has the ability to establish in post-fire A. chilensis-dominated forests resulting in mixed-species, uneven-aged forests. The ongoing increase in the abundance of N. dombeyi relative to A. chilensis represents a shift in composition and increased complexity in stand structure driven by ‘mal del ciprés’ and climatic variation.     

Efficiency of Immunotoxin Cytotoxicity Is Modulated by the Intracellular Itinerary

Pseudomonas exotoxin-based immunotoxins, including LMB-2 (antiTac(F_v)-PE38), are proposed to traffic to the trans-Golgi network (TGN) and move by a retrograde pathway to the endoplasmic reticulum, where they undergo translocation to the cytoplasm, a step that is essential for cytotoxicity. The retrograde transport pathways used by LMB-2 are not completely understood, so it is unclear if transit through specific organelles is critical for maximal cytotoxic activity. In this study, we used Chinese hamster ovary (CHO) cell lines that express chimeric constructs of CD25, the Tac antigen, attached to the cytoplasmic domain of the TGN-targeted transmembrane proteins, TGN38 and furin. These chimeras are both targeted to the TGN, but the itineraries they follow are quite different. LMB-2 was incubated with the two cell lines, and the efficiency of cell killing was determined using cell viability and cytotoxicity assays. LMB-2 that is targeted through the endocytic recycling compartment to the TGN via Tac-TGN38 kills the cells more efficiently than immunotoxins delivered through the late endosomes by Tac-furin. Although the processing to the 37 kDa active fragment was more efficient in Tac-furin cells than in Tac-TGN38 cells, this was not associated with enhanced cytotoxicity – presumably because the toxin was also degraded more rapidly in these cells. These data indicate that trafficking through specific organelles is an important factor modulating toxicity by LMB-2.     

VS411 Reduced Immune Activation and HIV-1 RNA Levels in 28 Days: Randomized Proof-of-Concept Study for AntiViral-HyperActivation Limiting Therapeutics

Background

A new class of antiretrovirals, AntiViral-HyperActivation Limiting Therapeutics (AV-HALTs), has been proposed as a disease-modifying therapy to both reduce Human Immunodeficiency Virus Type 1 (HIV-1) RNA levels and the excessive immune activation now recognized as the major driver of not only the continual loss of CD4⁺ T cells and progression to Acquired Immunodeficiency Syndrome (AIDS), but also of the emergence of both AIDS-defining and non-AIDS events that negatively impact upon morbidity and mortality despite successful (ie, fully suppressive) therapy. VS411, the first-in-class AV-HALT, combined low-dose, slow-release didanosine with low-dose hydroxycarbamide to accomplish both objectives with a favorable toxicity profile during short-term administration. Five dose combinations were administered as VS411 to test the AV-HALT Proof-of-Concept in HIV-1-infected subjects.

Methods

Multinational, double-blind, 28-day Phase 2a dose-ranging Proof-of-Concept study of antiviral activity, immunological parameters, safety, and genotypic resistance in 58 evaluable antiretroviral-naïve HIV-1-infected adults. Randomization and allocation to study arms were carried out by a central computer system. Results were analyzed by ANOVA, Kruskal-Wallis, ANCOVA, and two-tailed paired t tests.

Results

VS411 was well-tolerated, produced significant reductions of HIV-1 RNA levels, increased CD4⁺ T cell counts, and led to significant, rapid, unprecedented reductions of immune activation markers after 28 days despite incomplete viral suppression and without inhibiting HIV-1-specific immune responses. The didanosine 200 mg/HC 900 mg once-daily formulation demonstrated the greatest antiviral efficacy (HIV-1 RNA: −1.47 log₁₀ copies/mL; CD4⁺ T cell count: +135 cells/mm³) and fewest adverse events.

Conclusions

VS411 successfully established the Proof-of-Concept that AV-HALTs can combine antiviral efficacy with rapid, potentially beneficial reductions in the excessive immune system activation associated with HIV-1 disease. Rapid reductions in markers of immune system hyperactivation and cellular proliferation were obtained despite the fact that VS411 did not attain maximal suppression of HIV RNA, suggesting this effect was due to the HALT component.

Trial Registration

ITEudraCT 2007-002460-98     

Active PI3K pathway causes an invasive phenotype which can be reversed or promoted by blocking the pathway at divergent nodes

The PTEN/PI3K pathway is commonly mutated in cancer and therefore represents an attractive target for therapeutic intervention. To investigate the primary phenotypes mediated by increased pathway signaling in a clean, patient-relevant context, an activating PIK3CA mutation (H1047R) was knocked-in to an endogenous allele of the MCF10A non-tumorigenic human breast epithelial cell line. Introduction of an endogenously mutated PIK3CA allele resulted in a marked epithelial-mesenchymal transition (EMT) and invasive phenotype, compared to isogenic wild-type cells. The invasive phenotype was linked to enhanced PIP(3) production via a S6K-IRS positive feedback mechanism. Moreover, potent and selective inhibitors of PI3K were highly effective in reversing this phenotype, which is optimally revealed in 3-dimensional cell culture. In contrast, inhibition of Akt or mTOR exacerbated the invasive phenotype. Our results suggest that invasion is a core phenotype mediated by increased PTEN/PI3K pathway activity and that therapeutic agents targeting different nodes of the PI3K pathway may have dramatic differences in their ability to reverse or promote cancer metastasis.     

Calcitonin gene-related peptide biases Langerhans cells toward Th2-type immunity

Langerhans cells (LC) are epidermal dendritic cells capable, in several experimental systems, of Ag-presentation for stimulation of cell-mediated immunity. LC have been considered to play a key role in initiation of cutaneous immune responses. Additionally, administration of donor T cells to bone marrow chimeric mice with persistent host LC, but not mice whose LC have been replaced by donor cells, exhibit marked skin graft-vs-host disease, demonstrating that LC can trigger graft-vs-host disease. However, experiments with transgenic mice in which regulatory elements from human langerin were used to drive expression of diphtheria toxin, resulting in absence of LC, suggest that LC may serve to down-regulate cutaneous immunity. LC are associated with nerves containing the neuropeptide calcitonin gene-related peptide (CGRP), and CGRP inhibits LC Ag-presentation in several models including presentation to a Th1 clone. We now report that CGRP enhances LC function for stimulation of Th2 responses. CGRP exposure enhanced LC Ag presentation to a Th2 clone. Upon presentation of chicken OVA by LC to T cells from DO11.10 chicken OVA TCR transgenic mice, pretreatment with CGRP resulted in increased IL-4 production and decreased IFN-gamma production. CGRP also inhibited stimulated production of the Th1 chemokines CXCL9 and CXCL10 but induced production of the Th2 chemokines CCL17 and CCL22 by a dendritic cell line and by freshly obtained LC. Changes in production of these chemokines correlated with the effect of CGRP on mRNA levels for these factors. Exposure of LC to nerve-derived CGRP in situ may polarize them toward favoring Th2-type immunity.     

Identification of functional roles for both IL-17RB and IL-17RA in mediating IL-25-induced activities

IL-25 (IL-17E) is a unique IL-17 family ligand that promotes Th2-skewed inflammatory responses. Intranasal administration of IL-25 into naive mice induces pulmonary inflammation similar to that seen in patients with allergic asthma, including increases in bronchoalveolar lavage fluid eosinophils, bronchoalveolar lavage fluid IL-5 and IL-13 concentrations, goblet cell hyperplasia, and increased airway hyperresponsiveness. IL-25 has been reported to bind and signal through IL-17RB (IL-17BR, IL-17Rh1). It has been demonstrated recently that IL-17A signals through a heteromeric receptor composed of IL-17RA and IL-17RC. We sought to determine whether other IL-17 family ligands also utilize heteromeric receptor complexes. The required receptor subunits for IL-25 biological activities were investigated in vitro and in vivo using a combination of knockout (KO) mice and antagonistic Abs. Unlike wild-type mice, cultured splenocytes from either IL-17RB KO or IL-17RA KO mice did not produce IL-5 or IL-13 in response to IL-25 stimulation, and both IL-17RB KO and IL-17RA KO mice did not respond to intranasal administration of IL-25. Furthermore, treatment with antagonistic mAbs to either IL-17RB or IL-17RA completely blocked IL-25-induced pulmonary inflammation and airway hyperresponsiveness in naive BALB/c mice, similar to the effects of an antagonistic Ab to IL-25. Finally, a blocking Ab to human IL-17RA prevented IL-25 activity in a primary human cell-based assay. These data demonstrate for the first time that IL-25-mediated activities require both IL-17RB and IL-17RA and provide another example of an IL-17 family ligand that utilizes a heteromeric receptor complex.     

Involvement of RhoA/Rho kinase signaling in protection against monocrotaline-induced pulmonary hypertension in pneumonectomized rats by dehydroepiandrosterone

RhoA/Rho kinase (ROCK) signaling plays a key role in the pathogenesis of experimental pulmonary hypertension (PH). Dehydroepiandrosterone (DHEA), a naturally occurring steroid hormone, effectively inhibits chronic hypoxic PH, but the responsible mechanisms are unclear. This study tested whether DHEA was also effective in treating monocrotaline (MCT)-induced PH in left pneumonectomized rats and whether inhibition of RhoA/ROCK signaling was involved in the protective effect of DHEA. Three weeks after MCT injection, pneumonectomized rats developed PH with severe vascular remodeling, including occlusive neointimal lesions in pulmonary arterioles. In lungs from these animals, we detected cleaved (constitutively active) ROCK I as well as increases in activities of RhoA and ROCK and increases in ROCK II protein expression. Chronic DHEA treatment (1%, by food for 3 wk) markedly inhibited the MCT-induced PH (mean pulmonary artery pressures after treatment with 0% and 1% DHEA were 33+/-5 and 16+/-1 mmHg, respectively) and severe pulmonary vascular remodeling in pneumonectomized rats. The MCT-induced changes in RhoA/ROCK-related protein expression were nearly normalized by DHEA. A 3-wk DHEA treatment (1%) started 3 wk after MCT injection completely inhibited the progression of PH (mean pulmonary artery pressures after treatment with 0% and 1% DHEA were 47+/-3 and 30+/-3 mmHg, respectively), and this treatment also resulted in 100% survival in contrast to 30% in DHEA-untreated rats. These results suggest that inhibition of RhoA/ROCK signaling, including the cleavage and constitutive activation of ROCK I, is an important component of the impressive protection of DHEA against MCT-induced PH in pneumonectomized rats.